Concrete mathematics, a foundation for computer science, by Ronald L. Graham, Donald E. Knuth and Oren Patashnik. Pp 625. £24·95. 1989. ISBN 0-201-14236-8 (Addison-Wesley)

https://www.jstage.jst.go.jp/article/jsprs1975/37/6/37_6_39/_pdf

1998 IEEE International Conference on SMCに参加して

In this two-part paper, we consider the problem of adaptive multidimensional/multichannel signal detection in Gaussian noise with unknown covariance matrix. The test data (primary data) is assumed as a collection of sample vectors, arranged as the columns of a rectangular data array. The rows and columns of the signal matrix are both assumed to lie in known subspaces, but with unknown coordinates. Due to this feature of the signal structure, we name this kind of signal as the double subspace signal. Part I of this paper focuses on the adaptive detection in homogeneous environments, while Part II deals with the adaptive detection in partially homogeneous environments. Precisely, in this part, we derive the generalized likelihood ratio test (GLRT), Rao test, Wald test, as well as their two-step variations, in homogeneous environments. Three types of spectral norm tests (SNTs) are also introduced. All these detectors are shown to possess the constant false alarm rate (CFAR) property. Moreover, we discuss the differences between them and show how they work. Another contribution is that we investigate various special cases of these detectors. Remarkably, some of them are well-known existing detectors, while some others are still new. At the stage of performance evaluation, conducted by Monte Carlo simulations, both matched and mismatched signals are dealt with. For each case, more than one scenario is considered.

Adaptive Double Subspace Signal Detection in Gaussian Background—Part I: Homogeneous Environments

THE meetings of the Institution of Electrical Engineers will be resumed in London during the second half of the current session if the present conditions continue. This applies to the ordinary meetings, informal meetings, meetings of the three technical sections and of the London Students’ Section. As regards activities in the provinces, the various committees will decide in the light of local conditions whether they are able to carry out programmes of meetings, visits and functions. The first ordinary meeting of the programme for the second half of the session will take place on January 25, at 6 p.m., when a discussion on “Fire-Fighting Equipment for Electrical Installations”, based on the E.R.A. Report on this subject, will be introduced by Messrs. H. W. Swann, J. Hacking and R. A. McMahon.

Institution of Electrical Engineers

Accurate analytical approximations are derived for the equivalent transverse spot size, d/Γ (<5% error), and the transverse beamwidth θ1/2 (<2% error), of broad-waveguide-type diode lasers, over a wide range in waveguide width: from the first-order-mode cutoff to the third-order-mode cutoff. The analytical formulas are found to be in good agreement with experimental values. For low-series-resistance and thermal-resistance devices, it is found that the junction-temperature rise ΔTj in continuous wave (CW) operation is a strong function of both the characteristic temperature T1 for the external differential quantum efficiency ηD as well as of the heatsink thermal resistance. If the device has relatively temperature-insensitive ηD (i.e., T1≳1000 K) the maximum CW power as well as the power density at catastrophic optical mirror damage, PCOMD, are limited, for a given active-region material, only by the heatsink heat-removal ability. For large d/Γ, 0.97 μm emitting, 100 μm stripe InGaAs/InGaAs(P)/GaAs device...

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Design considerations and analytical approximations for high continuous-wave power, broad-waveguide diode lasers

An approach to optimal array pattern synthesis based on spherical harmonics is presented. The array processing problem in the spherical harmonics domain is expressed with a matrix formulation. The beamformer weight vector design problem is written as a multiply constrained problem, so that the resulting beamformer can provide a suitable trade-off among multiple conflicting performance measures such as directivity index, robustness, array gain, sidelobe level, mainlobe width, and so on. The multiply constrained problem is formulated as a convex form of second-order cone programming which is computationally tractable. We show that the pure phase-mode spherical microphone array can be viewed as a minimum variance distortionless response (MVDR) beamformer in the spherical harmonics domain for the case of spherically isotropic noise. It is shown that our approach includes the delay-and-sum beamformer and a pure phase-mode beamformer as special cases, which leads to very flexible designs. Results of simulations and experimental data processing show good performance of the proposed array pattern synthesis approach. To simplify the analysis, the assumption of equidistant spatial sampling of the wavefield by microphones on a spherical surface is used and the aliasing effects due to noncontinuous spatial sampling are neglected.

Optimal Modal Beamforming for Spherical Microphone Arrays

This letter deals with the problem of adaptive detection in partially-homogeneous Gaussian disturbance with unknown but persymmetric structured covariance matrix. Since no uniformly most powerful test exists for the problem at hand, we devise and assess two detection strategies based on the Rao test and the Wald test design criteria. Remarkably, both detectors ensure the constant false alarm rate property with respect to both the structure of the covariance matrix as well as the power level. The preliminary performance assessment, conducted by resorting to simulated data, has confirmed the effectiveness of the newly proposed detectors.

Persymmetric Rao and Wald Tests for Partially Homogeneous Environment

Persymmetric adaptive detection of distributed targets in partially-homogeneous environment

Spherical harmonics MUSIC versus conventional MUSIC

A new subspace-based autocalibration algorithm for a uniform circular array with unknown mutual coupling is presented in this letter. In allusion to the existing ambiguity problems and the limitation of nonzero coupling coefficients in earlier work by Lin and Yang, a more generalized iterative method is proposed to jointly estimate the direction-of-arrival (DOA) and unknown mutual coupling. It suffers from no ambiguity problems and does not require the prior knowledge of the number of nonzero elements in the coupling vector. Simulation results show the robustness, effectiveness, and higher estimated accuracy of the proposed algorithm.

Xiaochuan Ma

Papers

Optimal Modal Beamforming for Spherical Microphone Arrays

Persymmetric Rao and Wald Tests for Partially Homogeneous Environment

Persymmetric adaptive detection of distributed targets in partially-homogeneous environment

Spherical harmonics MUSIC versus conventional MUSIC

An Autocalibration Algorithm for Uniform Circular Array With Unknown Mutual Coupling