Mixed disturbance action for stabilized control systems (necessary conditions)

Solution of nonlinear partial differential equations from base equations

Given an integer /spl sigma/>1, a vector (/spl delta//sub 1/, /spl delta//sub 2/,..., /spl delta//sub /spl sigma/-1/), of nonnegative integers, and an undirected graph G=(V, E), an L(/spl delta//sub 1/, /spl delta//sub 2/,..., /spl delta//sub /spl sigma/-1/)-coloring of G is a function f from the vertex set V to a set of nonnegative integers, such that |f(u)-f(v)|/spl ges//spl delta//sub i/, if d(u,v)=i, for 1<i<(/spl sigma/-1), where d(u, v) is the distance (i.e., the minimum number of edges) between the vertices u and v. An optimal L(/spl delta//sub 1/, /spl delta//sub 2/,..., /spl delta//sub /spl sigma/-1/)-coloring for G is one using the smallest range /spl lambda/ of integers over all such colorings. This problem has relevant application in channel assignment for interference avoidance in wireless networks, where channels (i.e., colors) assigned to interfering stations (i.e., vertices) at distance i must be at least /spl delta//sub i/ apart, while the same channel can be reused in vertices whose distance is at least /spl sigma/. In particular, two versions of the coloring problem - L(2, 1, 1) and L(/spl delta//sub 1/, 1,..., 1) - are considered. Since these versions of the problem are NP-hard for general graphs, efficient algorithms for finding optimal colorings are provided for specific graphs modeling realistic wireless networks, including rings, bidimensional grids, and cellular grids.

Ahlswede has previously introduced an abstract correlated source (/spl Vscr//spl times//spl Wscr/,S) with outputs (/spl upsi/, /spl omega/)/spl isin/S/spl sub//spl Vscr//spl times//spl Wscr/, where persons P/sub /spl Vscr// and P/sub /spl Wscr// observe /spl upsi/ and /spl omega/, respectively. More recently, Orlitsky considered the minimal number C/sub m/ of bits to be transmitted in m rounds to inform P/sub /spl Wscr// about /spl upsi/ over one channel. He showed that C/sub 2//spl les/4C/sub /spl infin//+3 and that in general C/sub 2/NOT/spl sim/C/sub /spl infin//. We give a simple example for C/sub 3/NOT/spl sim/C/sub /spl infin//. However, for the new model inform P/sub /spl Wscr// over two channels, four rounds are optimal for this example-a result we conjecture in general. If both P/sub /spl Vscr// and P/sub /spl Wscr// are to be informed over two channels about the other outcome, we determine asymptotically the complexities for all sources. In our last model inform P/sub /spl Vscr// and P/sub /spl Wscr// over one channel for all sources the total number T/sub 2/ of required bits is known asymptotically and T/sub /spl infin// is bounded from below in terms of average degrees. There are exact results for several classes of regular sources. An attempt is made to discuss the methods of the subject systematically.

Let /spl delta//sub /spl Sigma// be a measure of the relative stability of a stable dynamical system /spl Sigma/. Let /spl tau//sub A(/spl Sigma//) be a measure of the computational efficiency of a particular algorithm A which verifies the stability property of /spl Sigma/. For two representative cases of /spl Sigma/, we demonstrate the existence of a particular measure /spl delta//sub /spl Sigma// and an algorithm A such that, /spl delta//sub /spl Sigma///spl tau//sub A(/spl Sigma//)=c where c depends possibly on the dimension of the system /spl Sigma/ and parameters which are specific to the algorithm A, but independent of any other system characteristics. In particular, given /spl Sigma/ and A, one can estimate /spl delta//spl Sigma/ by measuring /spl tau//sub A(/spl Sigma//).

We study some model control problems which arise in connection with optimal manipulation of dissipative quantum dynamics. It is shown that the problem of optimal control of quantum mechanical phenomenon in presence of dissipation can be reduced to the study of optimization problems associated with a class of constrained bilinear control systems. These bilinear systems x/spl dot/=(A+/spl Sigma//sub i//sup n/u/sub i/B/sub i/)x are characterized by the fact that the controls can be expressed as polynomial functions of fewer parameters, i.e. u/sub i/=g/sub i/ (/spl upsi//sub 1/, /spl upsi//sub 2/,...,/spl upsi//sub k/) where g/sub i/ are polynomials and k<n. A general study of these systems is expected to find immediate applications in coherent control of quantum mechanical phenomenon.

We prove that for any decision tree calculating a Boolean function f : {-1,1}/sup n/ /spl rarr/ {-1, 1}, Var[f] /spl les/ /spl Sigma/ /sub i=1/ /sup n/ /spl delta//sup i/Inf/sub i/(f), i = 1 where /spl delta//sup i/ is the probability that the ith input variable is read and Inf/sub i/(f) is the influence of the ith variable on f. The variance, influence and probability are taken with respect to an arbitrary product measure on {-1, 1}/sup n/n. It follows that the minimum depth of a decision tree calculating a given balanced function is at least the reciprocal of the largest influence of any input variable. Likewise, any balanced Boolean function with a decision tree of depth d has a variable with influence at least 1/d. The only previous nontrivial lower bound known was /spl Omega/(d2/sup -d/). Our inequality has many generalizations, allowing us to prove influence lower bounds for randomized decision trees, decision trees on arbitrary product probability spaces, and decision trees with nonBoolean outputs. As an application of our results we give a very easy proof that the randomized query complexity of nontrivial monotone graph properties is at least/spl Omega/(v/sup 4/3//p/sup 1/3/), where v is the number of vertices and p /spl les/ 1/2 is the critical threshold probability. This supersedes the milestone /spl Omega/(v/sup 4/3//p/sup 1/3/) bound of Hajnal (1991) and is sometimes superior to the best known lower bounds of Chakrabarti-Khot (2001) and Friedgut-Kahn-Wigderson (2002).

Bandpass modulators sampling at high IFs (/spl sim/200 MHz) allows direct sampling of the RF signal, reducing analog hardware, and makes it easier to realize completely software programmable receivers. This paper presents the circuit design of and test results from a continuous time tunable IF sampling 4/sup th/ order bandpass delta-sigma modulator implemented in InP HBT IC technology for use in a multi-mode digital receiver application. The bandpass /spl Delta//spl Sigma/ modulator is fabricated in AlInAs/GaInAs heterojunction bipolar technology with a peak unity current gain cutoff frequency (f/sub T/) of 130 GHz and a maximum frequency of oscillation (f/sub MAX/) of 130 GHz. The 4/sup th/ order bandpass /spl Delta//spl Sigma/ modulator consists of two bandpass resonators that can be tuned to optimize both wideband and narrowband operation. The IF is tunable from 140 MHz to 210 MHz in this /spl Delta//spl Sigma/ modulator for use in multiple platform applications. Operating from /spl plusmn/5 V power supplies, the fabricated 4/sup th/ order /spl Delta//spl Sigma/ modulator sampling at 4 GSPS demonstrates stable behavior and achieves a signal to (noise+distortion) ratio (SNDR) of 78 dB @ 1 MHz BW and 50 dB @ 60 MHz BW. The average SNDR performance measured on over 250 parts is 72.5 dB @ 1 MHz BW and 47.7 dB @ 60 MHz BW.

Using oversampled sigma-delta (/spl Sigma/-/spl Delta/) techniques a signal can be represented as a single bit binary data stream ({-1, 1}), with the quantization noise high pass filtered out of baseband. In this paper adaptive LMS digital filters are presented that directly use binary /spl Sigma/-/spl Delta/ input streams and update the PCM adaptive filter weights at the oversampled rate to realize architectures that are very suitable for mixed analog/digital VLSI implementation. Using the /spl Sigma/-/spl Delta/ adaptive architecture PCM values are multiplied by single bits, and can therefore be easily performed by a simple multiplexor. Also using the /spl Sigma/-/spl Delta/ approach, the decimation and interpolation stages required for converting from /spl Sigma/-/spl Delta/ to PCM (and vice-versa) suitable for Nyquist DSP algorithms are circumvented. The paper describes the sigma delta adaptive LMS filter architecture and presents preliminary results for adaptive echo cancellation using adaptive sigma delta and standard PCM architectures.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Step forward on nonlinear differential equations with the Atangana–Baleanu derivative: Inequalities, existence, uniqueness and method

This paper presents an investigation of the performance characteristics of a pair of bandpass Sigma-Delta (/spl Sigma/-/spl Delta/) analog-to-digital (A/D) converters. One of these /spl Sigma/-/spl Delta/ A/D converters has the conventional cascade-of-integrators structure while the other has the conventional cascade-of-resonators structure. These /spl Sigma/-/spl Delta/ A/D converters are subsequently compared in terms of their achievable signal-to-quantization noise ratios for corresponding (discrete) switched-capacitor implementations. Based on this comparison, a new bandpass /spl Sigma/-/spl Delta/ A/D converter structure is proposed which possesses the best practical features of both converters. These include, complementary signal and noise transfer functions and the fact that the zeros of the noise transfer function are constrained to lie on the unit-circle.

In this paper, the design of a continuous-time baseband sigma-delta (/spl Sigma//spl Delta/) modulator with an integrated mixer for intermediate-frequency (IF) analog-to-digital conversion is presented. This highly linear IF /spl Sigma//spl Delta/ modulator digitizes a GSM channel at intermediate frequencies up to 50 MHz. The sampling rate is not related to the input IF and is 13.0 MHz in this design. Power consumption is 1.8 mW from a 2.5-V supply. Measured dynamic range is 82 dB, and third-order intermodulation distortion is -84 dB for two -6-dBV IF input tones. Two modulators in quadrature configuration provide 200-kHz GSM bandwidth. Active area of a single IF /spl Sigma//spl Delta/ modulator is 0.2 mm/sup 2/ in 0.35-/spl mu/m CMOS.

It is well known that /spl Sigma/-/spl Delta/ A/D converters having complementary signal and noise transfer functions exhibit high signal-to-quantization-noise ratios (SQNRs) and high dynamic ranges (DRs), but that they tend to be overly sensitive to capacitor mismatches (potentially leading to unstable converter operation) in a corresponding switched-capacitor (SC) hardware implementation. Recently, a new class of /spl Sigma/-/spl Delta/ A/D converters was developed based on magnitude-squared or magnitude complementary signal and noise transfer functions to decrease the sensitivity to capacitor mismatches at the expense of slightly lower SQNRs and DRs. This paper is concerned with the development of a novel approach to the design of /spl Sigma/-/spl Delta/ A/D converters. This approach combines the transfer function complementarity (in the overall frequency band) with signal and noise transfer function magnitude complementarity (in the signal passband) to obtain a single /spl Sigma/-/spl Delta/ A/D converter with a cascade-of-resonators configuration. Consequently, the resulting A/D converters achieve not only high-stability (arising from magnitude complementarity), but also high DR and SQNR (arising from transfer function complementarity) in the SC hardware implementation. A practical application example is given to illustrate the results.

We present novel oversampled implementations of adaptive LMS FIR filters using sigma delta (/spl Sigma//spl Delta/) computation strategies. Using this approach in conjunction with /spl Sigma//spl Delta/ DACs and ADCs the need for expensive decimation and interpolation stages for the /spl Sigma//spl Delta/ codec has been circumvented. Hence the complete architecture can make considerable savings in total silicon area for a mixed signal ASIC implementation. The LMS algorithm performance of the /spl Sigma//spl Delta/ approach is shown to be comparable to the traditional Nyquist rate PCM LMS algorithm.

This paper presents a quadrature bandpass /spl Sigma//spl Delta/ modulator with continuous-time architecture. Due to the continuous-time architecture and the inherent anti-aliasing filter, the proposed /spl Sigma//spl Delta/ modulator needs no additional anti-aliasing filter in front of the modulator in contrast to quadrature bandpass /spl Sigma//spl Delta/ modulators with switched-capacitor architectures. The second-order /spl Sigma//spl Delta/ modulator digitizes complex analog I/Q input signals at 1-MHz intermediate frequency and operates within a clock frequency range of 25-100 MHz. The modulator chip achieves a peak signal-to-noise-distortion ratio (SNDR) of 56.7 dB and a dynamic range of 63.8 dB within a 1-MHz signal bandwidth and at a clock frequency of 100 MHz. Furthermore, it provides an image rejection of at least 40 dB. The 0.65-/spl mu/m BiCMOS chip consumes 21.8 mW at 2.7-V supply voltage.

A technique for shaping component mismatch error in the real and imaginary paths of a complex (quadrature) /spl Delta//spl Sigma/ are studied and simulated. Complex bandpass /spl Delta//spl Sigma/ modulators provide improved performance over a pair of real bandpass /spl Delta//spl Sigma/ modulators of the same order in the conversion of narrow-band quadrature intermediate frequency (IF) signals. This is possible due to elimination of redundant conjugate pairs of poles and zeros in its noise and signal transfer function. Mismatches in the modulators real and imaginary paths, however, results in spectral leakage of image band interference and image band quantization noise to the passband of the converted output. Strategic pole-zero placement, as well as adaptive techniques has been studied in earlier works. The work presented here takes advantage of the inherent dual paths of the complex bandpass /spl Delta//spl Sigma/ modulator to reduce component mismatch effects using a switched capacitor error shaping technique.