Wiener filters in canonical coordinates for transform coding,filtering, and quantizing

Canonical correlations are used to decompose the Wiener filter into a whitening transform coder, a canonical filter, and a coloring transform decoder. The outputs of the whitening transform coder are called canonical coordinates; these are the coordinates that are reduced in rank and quantized in our finite-precision version of the Gauss-Markov theorem. Canonical correlations are, in fact, cosines of the canonical, angles between a source vector and a measurement vector. They produce new formulas for error covariance, spectral flatness, and entropy     

Dialogue-based user models

The paper investigates several approaches to user modeling in natural-language dialogue systems. First, reasons are pointed out why user modeling has become so important in the last few years, and definitions are proposed for the notions of "user model" and "user modeling component." Then, techniques for constructing user models in the course of a dialogue are presented and recent proposals for representing a wide range of assumptions about a user's beliefs and goals in a system's knowledge base are surveyed. Examples for the application of user models in systems developed to date are presented, and some social implications are discussed. Finally, unsolved problems like coping with collective beliefs or resource-limited processes are investigated, and prospects for application-oriented research are outlined.     

Maximum Likelihood Estimation of Label Imperfection Probabilities and Its Use in the Identification of Mislabeled Patterns

This paper presents the problem of estimating label imperfections and the use of the estimation in identifying mislabeled patterns. Expressions for the maximum likelihood estimates of classification errors and a priori probabilities are derived from the classification of a set of labeled and unlabeled patterns. Expressions also are presented for the asymptotic variances of probability of correct classification and proportions. Simple models are developed for imperfections in the labels and for classification errors and are used in the formulation of a maximum likelihood estimation scheme. Schemes are presented for the identification of mislabeled patterns in terms of thresholds on the discriminant functions for both two-class and multiclass cases. Expressions are derived for the probability that the imperfect label identifi'cation scheme will result in a wrong decision and are used in computing thresholds. Furthermore, the results of practical applications of these techniques in the processing of remotely sensed multispectral data are presented.     

Quantum functional devices: resonant-tunneling transistors,circuits with reduced complexity, and multiple valued logic

Recent advances in the area of quantum functional devices are discussed. After a discussion of the functional device concept, resonant-tunneling bipolar transistors (RTBTs) with a double barrier in the base region are described. Design considerations for RTBTs with ballistic injection and the first observation of minority-electron ballistic RT are presented. RTBTs using thermionic injection and exhibiting a high peak-to-valley ratio at room temperature in the transfer characteristics are also described. Multiple-state RTBTs and their DC and microwave performance are then discussed. Circuit applications of RTBTs also are discussed. It is shown that RTBTs allow the implementation of many analog and digital circuit functions with a greatly reduced number of transistors and show considerable promise for multiple-valued logic. Experimental results on frequency multipliers and parity bit generators are presented. Analog-to-digital converters are memory circuits are also discussed. Two novel superlattice-base transistors are reported. Negative transconductance is achieved by suppression of injection into minibands. Gated quantum-well RT transistors are also discussed     

Choosing the best battery for portable equipment

The ways in which a battery can affect the design and performance of a product are discussed, identifying the significant battery characteristics. Two new primary (single-use) batteries and two secondary (rechargeable) batteries that are widely used are described. The issues of cost and safety are examined. Guidelines are given for deciding the size and number of batteries to use in a design     

Phase Error Characteristics of a Second-Order Phase-Lock Loop

An analytical expression for the phase error characteristics of a second-order phase-lock loop (PLL) is determined using the results of a previous nonlinear analysis. The characteristics determined are for sinusoidal FM in the absence of noise. Theoretical and experimental results are compared and are in close agreement. The theoretical results are useful as a design aid and in determining the proper parameters for the operation of a second-order PLL.     

Performance boundaries for prioritized multiplexing systems

Systems in which many data sources are multiplexed over a single communication channel are considered. Data from all the sources are generated in fixed-length packets and are stored in a common buffer with finite capacity. Packets that overflowed or were removed from the buffer prior to transmission are lost. The system performance measure is the set of packet loss probabilities associated with the sources. Queueing disciplines vary depending on the stringency of prioritization and the utilization of the system resources. The set of all possible performances is characterized as we span the set of all queueing disciplines. Whether a given performance is possible can be deduced. Strategies that achieve the minimum overall loss probability are identified. The extreme disciplines are specified, and their performances are calculable by means of a given algorithm.     

Gaussian beam optical systems with high gain or high loss media

Coherent electromagnetic wave amplifiers with non-negligible gain per wavelength are included in the Gaussian beam matrix formalism and a procedure is developed for propagating Gaussian beams in optical systems that may include unsaturated amplifiers and similar absorbers. Standard formulas for beam spotsize and radius of curvature in a uniform medium are generalized in a new way to include gain or loss. An asymmetric focal shift and a potentially infinite spotsize are predicted. These dramatic effects are interpreted physically     

Butt-end forming electrodes for dense electron beams and axisymmetric Brillouin formations

Exact solutions are constructed for the butt-end region of electron beams in the form of finite-length cylinders; truncated cones; cylindrical and conical rings; toroidal, spherical, and ellipsoidal Brillouin formations; a cylindrical magnetron in the subcritical mode; and a cylindrical diode. Problems for finite-length cylinders with elliptic and circular cross sections are investigated. The cylinders are considered in the presence of a uniform longitudinal magnetic field for the case when the longitudinal velocity in a flow exhibits a cycloidal variation and the Cauchy conditions are exactly fulfilled on the flow’s boundary. Relativistic and nonrelativistic flows are analyzed. In the latter case, both the electrostatic and magnetostatic problems are solved. Solution of the magnetostatic problem provides for the continuous transition from the eigenfield to the external magnetic field on a beam’s boundary.     

Physical limitations of antennas in a lossy medium

The dissipated power and the directivity of antennas in a homogeneous, lossy medium are systematically analyzed in this paper. The antennas are ideal and located inside a lossless sphere. In the lossy space outside the sphere, the electromagnetic fields are expanded in a complete set of vector wave functions. The radiation efficiency, the directivity, and the power gain are defined for antennas in a lossy medium, and the optimal values of these quantities are derived. Simple relations between the maximal number of ports, or channels, an antenna can use and the optimal directivity and gain of the antenna are presented.     

Conservation principles for plasmas and relativistic electron beams

Many useful conservation theorems are derived for relativistic electron beams and anisotropic plasmas. All these theorems are valid for confined-flow and irrotational-flow devices, and cold, collisionless plasmas. All the theorems are derived in a similar way, and a generalization of this method, using linear operators, is given. Among the power theorems discussed are: Tonks' theorem, the instantaneous and sinusoidal small-signal theorems, the energy theorem, a large-disturbance theorem, the Manley-Rowe formulas, an ac power theorem, and a cross-correlation theorem. Contributions to power and energy from surface waves are included. Allowing for relativistic flow and writing all equations in the laboratory frame does not significantly complicate the theorems, and in fact clarifies them somewhat. Many simple applications are discussed, although not in detail. Among these are: small-signal energy, power, and passivity; energy velocity in electron beam and plasma wave-guides; and a conservation theorem for multiple electron beams and electron beam-plasma interactions.     

Circulators for microwave and millimeter-wave integrated circuits

The requirements for circulators for use in combination with microwave and millimeter-wave integrated circuits are reviewed, with special emphasis on modules for phased-array antennas. Recent advances in broadbanding and in miniaturization are summarized. Novel types of circulators that are fabricated by attaching a ferrite disc and a suitable coupling structure to the surface of a dielectric of semiconductor substrate (quasimonolithic integration) are described. Methods for achieving complete monolithic integration are also discussed     

Magnetostatic surface waves on a y.i.g. slab

Magnetostatic surface waves are identified in microwave-frequency experiments with a single-crystal y.i.g. slab. Slow travelling waves having k numbers that are high in the magnetostatic range are studied in a pulse experiment, and fast waves with k numbers low in the range are observed in a c.w. test.     

Considerations in the design of drive systems for on-the-road electric vehicles

The energy and power requirements of a class of on-the-road electric vehicles are developed, and acceleration and speed characteristics of such vehicles in urban traffic are discussed. Curves of average speed under different conditions of traffic are presented, as are curves of average power required during acceleration, average power required during cruising, and peak power required. A dc drive system for propulsion of such a vehicle and an ac drive system appropriate for such an application are described. The two kinds of system are then compared, on an economic as well as a technical basis. A procedure for designing an electric vehicle is outlined, pertinent fields in which research and development are needed are listed, and a reference list on electric vehicles is included.     

Equivalent Circuits for Discontinuities in Balanced Strip Transmission Line

Theoretical formulas are derived for the equivalent circuit parameters of a variety of discontinuties in balanced strip transmission line. These formulas are simple in form and are obtained by employing a small aperture procedure or a Babinet equivalence procedure in conjunction with an approximate model of the line. The results for a number of discontinuities are presented and comparison is made with the available measured data.     

Reliability of quantum-mechanical communication systems

We are concerned with the detection of a set ofMmessages that are transmitted over a channel disturbed by chaotic thermal noise when quantum effects in the communication systems are taken into account. Our attention is restricted to the special case in which the density operators specifying the state of the received field are commutative. In particular, the performance of two special communication systems is evaluated. For a system in which orthogonal signals with known amplitudes and random phases are transmitted over an additive white Gaussian channel, the structure of an optimum receiver is found. Expressions for the system reliability function and channel capacity are derived. For a system in which orthogonal signals are transmitted over a Rayleigh fading channel, the optimum performance is obtained. The optimum degree of diversity for an equal-strength diversity system is found numerically as a function of the average thermal-noise energy and information rate.     

Propagation characteristics of dielectric-rod-loaded waveguides

A general technique for calculating the propagation characteristics of a waveguide with arbitrary cross-sectional shape loaded with a circular dielectric rod is presented. The waveguide fields, which are represented as a sum of functions satisfying the homogeneous Helmholtz equation and the boundary conditions at the rod surface, are point-matched at the surface of the waveguide. Numerical examples of a rod centered in a square guide and off center in a circular guide are given, and results for a rod centered in a rectangular cavity are compared with measured data     

随机振动中的参数介绍及计算方法

介绍了随机振动试验中的重要参数及其计算方法，对实际试验的两个图表中的参数进行了计算，比较了两个图表振动能量的大小．进而得出了一种比较随机振动能量大小的方法。     

Dyadic Green's function in bounded media

A new theory for the evaluation of the dyadic Green's functions in a homogeneous medium bounded by perfectly conducting walls is presented. The peculiarities of this theory are 1) the Green's functions are systematically and explicitly decomposed in a singular and an analytical part, and 2) these two parts are formulated in a general manner, i.e., independent on the boundaries. As an application, the Green's functions in a conical guide are evaluated.