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Numbers of citations of outstanding conference papers (OCPs) of IEEE Nuclear and Space Radiation Effects Conferences (NSRECs) from 1966 to 2017 are compared with citations of the most highly cited papers (HCPs) of the corresponding special issues of the IEEE TRANSACTIONS ON NUCLEAR SCIENCE (TNS), as well as average numbers of citations and cumulative $h$ index, $h_{\mathrm {cum}}$ , for all TNS papers published in the same year. 85% of NSREC OCPs are cited at a higher rate than the average for all TNS articles in that year. 55% of NSREC OCP citation totals are higher than $h_{\mathrm {cum}}$ for TNS in that year; these rank among the ~8% most highly cited TNS papers for that year. In ~10% of cases, the NSREC OCP is also the most HCP. Similarly high citation impact is found for papers nominated as candidates for OCPs. Radiation effects papers published in annual NSREC special issues comprise a significant fraction of all TNS articles cited $h_{\mathrm {cum}}$ times or more. These results support the use of $h_{\mathrm {cum}}$ as a metric of citation impact in this work and show that the NSREC OCP process generally meets awards criteria guidelines for impact. Potential reasons for variations in citation rates are discussed, and recommendations are provided to enhance the awards process.

Conductivity is an important parameter which has definite correlation with the amount of moisture present within the transformer insulation. However, in existing methods conductivity is usually estimated from time domain (PDC) measurement, which is inadvertently noise prone and time consuming. Considering this issue, in this article presents a novel technique for conductivity estimation for moisture sensing of oil-paper insulation using frequency domain spectroscopy measurement (FDS). To this end, FDS measurement of oil-paper insulation was performed from 50mHz to 1kHz to obtain the imaginary complex permittivity $\varepsilon ''$ ( $\omega$ ), which is a function of conductivity ( $\sigma$ ) as well as imaginary complex susceptibility $\chi ''$ ( $\omega$ ). From the knowledge of frequency variation of both $\sigma $ and $\chi ''$ ( $\omega$ ), we developed an electrical equivalent model of the insulation. The equivalent model parameters were optimized until $\varepsilon ''$ ( $\omega$ ) computed from the proposed model and that obtained from original FDS measurement were almost identical. The conductivity values obtained from the equivalent model showed good agreement when compared with PDC measurement. To validate the practicability of the proposed method, experiments were conducted on various test samples and also on a few real life transformers. Most importantly, the measurement time was found to be reduced by 78.5%, enabling diagnosis of transformer insulation at a significantly reduced time.

This paper studies the second-order coding rates for memoryless channels with a state sequence known non-causally at the encoder. In the case of finite alphabets, an achievability result is obtained using constant-composition random coding, and by using a small fraction of the block to transmit the empirical distribution of the state sequence. For error probabilities less than 0.5, it is shown that the second-order rate improves on an existing one based on independent and identically distributed random coding. In the Gaussian case (dirty paper coding) with an almost-sure power constraint, an achievability result is obtained using random coding over the surface of a sphere, and using a small fraction of the block to transmit a quantized description of the state power. It is shown that the second-order asymptotics are identical to the single-user Gaussian channel of the same input power without a state.

Citation count is a widely-used indicator for calculating the academic impact of scientific papers, but it is limited because it assumes all citations are of similar value and weights each equally. By examining the influence changes in papers’ citation distribution and the cited papers’ unequal contributions to the citing ones, this study aims to distinguish citations and, on this basis, evaluate the academic impact of the papers. Three indices of time-weighted citation count, citation width and citation depth are proposed to distinguish citations and perform the evaluation task. The experimental results show that papers exhibit different influence intensity characteristics in different periods of citation life. Those papers got larger citations in recent years are more influential and more active to gain new citations. The papers show the different scope of influence in their citing environment, although they were originally published in the same journal and the same year. In addition, the different frequency of mentions and the different subject similarities with the citing works suggest that the papers have different importance and usefulness for subsequent research. These results suggest that these three indices do help to distinguish citations and reveal the different intensity and contribution of influences in citations. Finally, the three indices are integrated into the overall evaluation of the academic impact of the paper, and the weight of each index is calculated by the entropy weight method. Quite different overall impacts in the paper are shown due to their different performances in the three indices, even though they have the same total number of citations.

We propose a density evolution based dirty-paper code design framework that combines trellis coded quantization with multi-level low-density parity-check (LDPC) codes. Unlike existing design techniques based on Gaussian approximation and EXIT charts, the proposed framework tracks the empirically collected log-likelihood ratio (LLR) distributions at each iteration, and employs density evolution and differential evolution algorithms to design each LDPC component code. The performance of the dirty-paper codes designed using the proposed method comes within 0.37 dB of the theoretical limit at 1 bit per sample transmission rate, achieving an 0.21 dB gain over the best known result.

We propose a robust close-to-capacity dirty-paper coding (DPC) design framework in which multi-level low density parity check (LDPC) codes and trellis coded quantization (TCQ) are employed as the channel and source coding components, respectively. The proposed design framework is robust in the sense that it yields close to capacity solutions in the high-, medium-, and low-rate regimes. This is in contrast to existing practical DPC schemes that perform well only in one or two of these regimes, but not all three. We design codes for transmission rates of 0.5, 1.0, 1.5, and 2.0 bits/sample (b/s) using one, two, three, and four LDPC levels; at a block length of 2×105, the codes perform 0.95, 0.58, 0.55, and 0.54 dB from the corresponding information theoretic limits, respectively. We also propose a low-complexity decoding scheme that does not involve iterative message passing between the source and channel decoders; the low-complexity scheme performs only 1.08, 0.85, and 0.79 dB away from the theoretical limits at transmission rates of 1.0, 1.5, and 2.0 b/s, respectively.

We consider practical schemes for binary dirty-paper channels and broadcast channels (BCs) with two receivers and varying channel quality. With the BC application in mind, this paper proposes a new design for binary dirty paper coding (DPC). By exploiting the concept of coset binning, the complexity of the system is greatly reduced when compared to the existing works. Some design challenges of the coset binning approach are identified and addressed. The proposed binary DPC system achieves similar performance to the state-of-the-art, superposition-coding-based system while demonstrating significant advantages in terms of complexity and flexibility of system design. For binary BCs, achieving the capacity generally requires the superposition of a normal channel code and a carefully designed channel code with non-uniform bit distribution. The non-uniform bit distribution is chosen according to the channel conditions. Therefore, to achieve the capacity for binary BCs with varying channel quality, it is necessary to use quantization codes of different rates, which significantly increases the implementation complexity. In this paper, we also propose a broadcast scheme that generalizes the concept of binary DPC, which we term soft DPC. By combining soft DPC with time sharing, we achieve a large percentage of the capacity for a wide range of channel quality with little complexity overhead. Our scheme uses only one fixed pair of codes for users 1 and 2, and a single quantization code, which possesses many practical advantages over traditional time sharing and superposition coding solutions and provides strictly better performance.

In this paper, an efficient greedy scheduler for zero-forcing dirty-paper coding (ZF-DPC), which can be incorporated in complex Householder QR factorization of the channel matrix, is proposed. The ratio of the complexity of the proposed scheduler to the complexity of the channel matrix factorization required by ZF-DPC is O(M-1), while such ratio for the original greedy scheduler is O(M), where M is the number of transmitters. Therefore, the new scheduler reduces the overhead of scheduling from being the bottleneck of ZF-DPC to being negligible.

A binned dirty-paper code (DPC) divides a set of codewords into a number of bins. The codeword in the bin that has the maximum correlation with the side information is selected as the transmitted dirty-paper codeword. This letter derives and verifies the analytical bit-error rate (BER) expression of binned orthogonal block code used as DPC in watermarking applications. The BER trends of such orthogonal DPC under constant code length or constant code rate constrains are analyzed. Finally, we propose a new class of DPC based on binned bi-orthogonal codes and demonstrate its BER performance gain over orthogonal DPC.

Parallel test paper generation is a biobjective distributed resource optimization problem, which aims to generate multiple similarly optimal test papers automatically according to multiple user-specified assessment criteria. Generating high-quality parallel test papers is challenging due to its NP-hardness in both of the collective objective functions. In this paper, we propose a submodular memetic approximation algorithm for solving this problem. The proposed algorithm is an adaptive memetic algorithm (MA), which exploits the submodular property of the collective objective functions to design greedy-based approximation algorithms for enhancing steps of the multiobjective MA. Synergizing the intensification of submodular local search mechanism with the diversification of the population-based submodular crossover operator, our algorithm can jointly optimize the total quality maximization objective and the fairness quality maximization objective. Our MA can achieve provable near-optimal solutions in a huge search space of large datasets in efficient polynomial runtime. Performance results on various datasets have shown that our algorithm has drastically outperformed the current techniques in terms of paper quality and runtime efficiency.

Dirty paper coding (DPC) scheme is the capacity achieving transmission technique in multiuser MIMO downlink channels. As a suboptimal solution to DPC, successive zero-forcing DPC (SZF-DPC) has been proposed recently. The zero-interference constraint in designing the precoding matrices limits the number of supportable users. In this correspondence, we propose three low-complexity suboptimal user scheduling algorithms to exploit the multiuser diversity gain in SZF-DPC as the number of users grows. The first algorithm greedily maximizes the true sum rate. The second algorithm is based on eigenvalues. The third algorithm relies on the diagonal elements of the effective channel matrix since eigenvalues and diagonal entries of a Hermitian matrix have a strong relationship. Simulation results show that the proposed scheduling algorithms can obtain a significant fraction of sum rate of the optimal solution. Furthermore, the performance analysis is provided to prove that the proposed user selection algorithms can achieve the same asymptotic sum rate as that of DPC.

The "writing on dirty paper"-channel model offers an information-theoretic framework for precoding techniques for canceling arbitrary interference known at the transmitter. It indicates that lossless precoding is theoretically possible at any signal-to-noise ratio (SNR), and thus dirty-paper coding may serve as a basic building block in both single-user and multiuser communication systems. We design an end-to-end coding realization of a system materializing a significant portion of the promised gains. We employ multidimensional quantization based on trellis shaping at the transmitter. Coset decoding is implemented at the receiver using "virtual bits." Combined with iterative decoding of capacity-approaching codes we achieve an improvement of 2dB over the best scalar quantization scheme. Code design is done using the EXIT chart technique.

We compare the capacity of dirty-paper coding (DPC) to that of time-division multiple access (TDMA) for a multiple-antenna (multiple-input multiple-output (MIMO)) Gaussian broadcast channel (BC). We find that the sum-rate capacity (achievable using DPC) of the multiple-antenna BC is at most min(M,K) times the largest single-user capacity (i.e., the TDMA sum-rate) in the system, where M is the number of transmit antennas and K is the number of receivers. This result is independent of the number of receive antennas and the channel gain matrix, and is valid at all signal-to-noise ratios (SNRs). We investigate the tightness of this bound in a time-varying channel (assuming perfect channel knowledge at receivers and transmitters) where the channel experiences uncorrelated Rayleigh fading and in some situations we find that the dirty paper gain is upper-bounded by the ratio of transmit-to-receive antennas. We also show that min(M,K) upper-bounds the sum-rate gain of successive decoding over TDMA for the uplink channel, where M is the number of receive antennas at the base station and K is the number of transmitters.

In this correspondence, we compare the achievable throughput for the optimal strategy of dirty paper coding (DPC) to that achieved with suboptimal and lower complexity linear precoding techniques (zero-forcing and block diagonalization). Both strategies utilize all available spatial dimensions and therefore have the same multiplexing gain, but an absolute difference in terms of throughput does exist. The sum rate difference between the two strategies is analytically computed at asymptotically high SNR. Furthermore, the difference is not affected by asymmetric channel behavior when each user has a different average SNR. Weighted sum rate maximization is also considered. In the process, it is shown that allocating user powers in direct proportion to user weights asymptotically maximizes weighted sum rate.

In this paper, we present a practical method to construct dirty paper coding (DPC) schemes using sum codes. Unlike the commonly used approach to DPC where the coding scheme involves concatenation of a channel code and a quantization code, the proposed method embodies a unified approach that emulates the binning method used in the proof of the DPC result. Auxiliary bits are used to create the desired number of code vectors in each bin. Sum codes are obtained when information sequences augmented with auxiliary bits are encoded using linear block codes. Sum-code-based DPC schemes can be implemented using any linear block code, and entail a relatively small increase in decoder complexity when compared to standard communication schemes. They can also lead to significant reduction in transmit power in comparison to standard schemes.

This letter presents closed-form capacity bounds for an exponential version of the dirty paper channel (EDPC). The EDPC can be used to model the non-coherent Gaussian dirty paper channel (GDPC). First, a superposition modulation-like technique is used to obtain a capacity upper bound for the EDPC. Then, a closed-form capacity lower bound for the EDPC is obtained by using a Costa-like strategy. Using this lower bound and exploiting the asymptotic properties of high signal to noise ratios (SNRs), we obtain the high-SNR capacity of the EDPC which is intriguingly analogous to the complex-valued GDPC. Finally, a closed-form capacity lower bound for the EDPC is given which is useful in the weak interference regime.

The authors of [1] have become aware that several equations in [1] were presented with errors. As confirmed in this brief note, neither do the errors invalidate the game theoretic approach proposed in [1] , nor violate the equilibrium of the approach. However, the parameter selection, which is required to preserve the validity and unique equilibrium of the approach, is affected by the errors. We correct the equations with detailed mathematical derivations in the note.

Wet paper codes (WPCs) are designed for steganography, in which the sender and recipient do not need to share the changeable positions. In this paper, we propose the N -page construction for wet paper coding, which can generate a family of WPCs following the upper bound on embedding efficiency from one single WPC. The Paper Folding method, one of our previous methods, is a special case of the N-page construction with N=2k . We deduce recursions for calculating embedding efficiency of N-page construction, and obtain explicit expression on embedding efficiency of 2k-page construction. Furthermore, we derive the limit of distance between the embedding efficiency of 2k-page construction and the upper bound of embedding efficiency as k tends to infinity. Based on the limit, we analyze how the embedding efficiency is influenced by the proportion of wet pixels (wet ratio) in the cover, showing that embedding efficiency only drops about 0.32 as the wet ratio increases to 0.9999.

A thermal aging experiment was conducted for oil-paper insulation to evaluate the insulation's response under thermal stress. Oil-papers at different aging stages were used to create oil-paper bound gas cavity specimens, which were used to collect data on degrees of polymerization (DP) and partial discharge (PD). Evaluation of oil-paper aging was based on statistical operators of PD and factor analysis was used to extract the principle parameters of PD. Three types of fuzzy clustering approaches were used to classify PD of aged oil-paper: the fuzzy c-means, the kernel fuzzy c-means, and the possibilistic fuzzy c-means. The clustering results showed that the possibilistic fuzzy c-means clustering was capable of classifying PD of oil-paper bound gas cavity specimens. The factor analysis method was also verified to be helpful in fuzzy clustering of PD data samples by reducing number of parameters.

This paper presents two algebraic methods for constructing high performance and efficiently encodable nonbinary quasi-cyclic LDPC codes based on arrays of special circulant permutation matrices and multi-fold array dispersions. Codes constructed based on these methods perform well over the AWGN and other types of channels with iterative decoding based on belief-propagation. Experimental results show that over the AWGN channel, these non-binary quasi-cyclic LDPC codes significantly outperform Reed-Solomon codes of the same lengths and rates decoded with either algebraic hard-decision Berlekamp-Massey algorithm or algebraic soft-decision Kotter-Vardy algorithm. Also presented in this paper is a class of asymptotically optimal LDPC codes for correcting bursts of erasures. Codes constructed also perform well over flat fading channels. Non-binary quasi-cyclic LDPC codes have a great potential to replace Reed-Solomon codes in some applications in communication environments and storage systems for combating mixed types of noises and interferences.

A novel noncoherent block coding scheme, called noncoherent block-coded MPSK (NBC-MPSK), was proposed recently. In this paper, we present further research results on NBC-MPSK. We first focus on the rotational invariance (RI) of NBC-MPSK. Based on the RI property of NBC-MPSK with multistage decoding, a noncoherent near-optimal linear complexity multistage decoder for NBC-MPSK is proposed. Then we investigate a tree-search ML decoding algorithm for NBCMPSK. The derived algorithm is shown to have low complexity and excellent error performance. In this paper, we also utilize the idea of the NBC-MPSK to design noncoherent space-time block codes, called noncoherent space-time block-coded MPSK (NSTBC-MPSK). For two transmit antennas, we propose a signal set with set partitioning and derive the minimum noncohent distance of NSTBC-MPSK with this signal set. For the decoding of NSTBC-MPSK, we modify the ML decoding algorithm of NBC-MPSK and propose an iterative hard-decision decoding algorithm. Compared with training codes and unitary space-time modulation, NBC-MPSK and NSTBC-MPSK have larger minimum noncoherent distance and thus better error performance for the noncoherent ML decoder.

A bound on the capacity of the causal dirty-paper channel with arbitrary interference and general independent identically distributed additive noise is derived. In particular, it is shown that for the case of Gaussian noise, the capacity is upper bounded by log2(1+SNR/e) bits per real dimension. This bound is useful for SNR ≤ e(e-2) .

International audience; The huge potential of ultra wide band impulse radio (UWB IR) with multiple access was initially evaluated using the standard Gaussian approximation which assumed that multi user interference could be approximated as classical Gaussian noise. Later the standard Gaussian approximation has been proved to be invalid in several cases. Thus the performance of the classical UWB IR correlation receiver dramatically reduces. We show in this paper how the non Gaussianity of the multi user interference can be exploited, turning the non Gaussianity into an advantage, increasing the performance with respect to the Gaussian interference case which was supposed to be too optimistic until now.

Costa's celebrated ldquowriting on dirty paperrdquo (WDP) shows that the power-constrained channel Y=X+S+Z, with Gaussian Z, has the same capacity as the standard AWGN channel Y=X+Z, provided that the ldquointerferencerdquo S (no matter how strong it is) is known at the transmitter. While this ability for perfect interference cancelation is very appealing, it relies heavily on the Gaussianity of the (unknown) noise Z. We construct an example of ldquobadrdquo noise for writing on dirty paper, namely, ldquodifference set noiserdquo. If the interference S is strong, then difference-set noise limits the WDP capacity to at most 2 bits. At the same time, like in the AWGN case, the zero-interference capacity grows without bound with the input constraint. Thus almost 100% of the available capacity is lost in WDP in the presence of difference-set noise. This high capacity loss is due to the ldquoentropy amplification propertyrdquo (EAP) of noise with an aperiodic probability distribution. Using the EAP and the duality between WDP and Wyner-Ziv source coding, we also give an example of dramatic rate-loss in quantizing encrypted source.

This paper is concerned with construction of efficiently encodable nonbinary quasi-cyclic LDPC codes based on finite fields. Four classes of nonbinary quasi-cyclic LDPC codes are constructed. Experimental results show that codes constructed perform well with iterative decoding using a fast Fourier transform based q-ary sum-product algorithm and they achieve significant coding gains over Reed-Solomon codes of the same lengths and rates decoded with either algebraic hard- decision Berlekamp-Massey algorithm or algebraic soft-decision Kotter-Vardy algorithm.

A l-Bayesian erasure test (BET) based on order statistics with diversity reception for noncoherent M-ary frequency shift keying (FSK) signaling is examined. In the l-BET, the M-ary FSK symbol is erased whenever the a posteriori probability of correct decision, which is a function of the l-largest sums of energy detector outputs, is less than a threshold. For binary FSK signaling in Rayleigh flat fading channels, the 2-BET is found to be the same as the difference threshold test (DTT), which declares an erasure whenever the difference between the largest and the second largest sums of energy detector outputs is less than a threshold. The output threshold test (OTT), which declares an erasure whenever the largest sum of energy detector outputs is less than a threshold, is proved equivalent to the 1-BET for the Rayleigh flat fading channel. Closed-form expressions for the probabilities of correct decision and symbol error for the DTT, Viterbi's ratio threshold test (RTT), and the OTT are derived when square-law combining (SLC) diversity is used. Several erasure tests including the Z-BET, the RTT, the OTT, and the DTT are compared in terms of probability of codeword error. The 2-BET provides almost the same performance as the BET that requires all the sums of energy detector outputs. The 2-BET provides power gains of 0.9 dB and 0.7 dB over the RTT for (7, 3) and (15, 7) Reed-Solomon (RS) codes, respectively, when the probability of codeword error is 10-3 and the diversity order is one.

Partial transmit sequence (PTS) is a proven technique to reduce the peak-to-average power ratio (PAPR) in orthogonal frequency division multiplexing (OFDM) systems. It achieves considerable PAPR reduction without distortion, but the high computational complexity of multiple Fourier transforms is a problem in practical systems. To address the complexity, signals at the middle stages of an ?-point radix FFT using decimation in frequency (DIF) are employed for PTS subblocking. We formulate OFDM symbols based on these signals to exploit the periodic autocorrelation function (ACF) of the vectors in the PTS subblock partitioning. Error-correcting codes (ECCs) are employed in the subblocking for the PTS radix FFT. This new technique significantly decreases the computational complexity while providing comparable PAPR reduction to ordinary PTS (O-PTS), even with a small number of stages after PTS partitioning. Numerical results are presented which confirm the PAPR improvements.

This letter presents two results for multiuser wireless systems employing dirty-paper coding strategies along with greedy scheduling over the broadcast multiple-input multiple-output channel. Specifically, an efficient and suboptimal downlink scheduler is proposed to approximate the maximum sum rate using equal power allocation, and it is shown to approach the maximum sum rate of optimal power allocation for a large number of users under optimal scheduling. The second result demonstrates that the average maximum sum rate can be tightly upper bounded when spatial multiplexing is maximized.

The construction of finite-length irregular LDPC codes with low error floors is currently an attractive research problem. In particular, for the binary erasure channel (BEC), the problem is to find the elements of selected irregular LDPC code ensembles with the size of their minimum stopping set being maximized. Due to the lack of analytical solutions to this problem, a simple but powerful heuristic design algorithm, the approximate cycle extrinsic message degree (ACE) constrained design algorithm, has recently been proposed. Building upon the ACE metric associated with a cycle in a code graph, we introduce the ACE spectrum of LDPC codes as a useful tool for evaluation of codes from selected irregular LDPC code ensembles. Using the ACE spectrum, we generalize the ACE constrained design algorithm, making it more flexible and efficient. We justify the ACE spectrum approach through examples and simulation results.

We treat the problem of outage minimization via power control in MIMO systems with quantized feedback. We formulate the optimal quantized power control design for a general MIMO system and provide the numerical procedure for finding the optimal solution. Our results not only extend but also show the deficiency of the existing quantized power control schemes for MISO systems. We further propose a design based on the pre-evaluation of the packet error rate performance of practical MIMO systems employing short-length LDPC codes and QAM modulations and with possibly unreliable feedback links. It is demonstrated that with only a few bits of feedback, the resulting quantized power control strategy achieves considerable gain over a system without power control.

Bandwidth efficient parallel-concatenated Turbo Trellis Coded Modulation (TTCM) schemes were designed for communicating over uncorrelated Rayleigh fading channels. A symbol-based union bound was derived for analysing the error floor of the proposed TTCM schemes. A pair of In-phase (I) and Quadrature-phase (Q) interleavers were employed for interleaving the I and Q components of the TTCM coded symbols, in order to attain an increased diversity gain. The decoding convergence of the IQ-TTCM schemes was analysed using symbol-based EXtrinsic Information Transfer (EXIT) charts. The best TTCM component codes were selected with the aid of both the symbolbased union bound and non-binary EXIT charts, for designing capacity-approaching IQ-TTCM schemes in the context of 8 PSK, 16 QAM, 32 QAM and 64 QAM modulation schemes.

We propose multi-level coding and successive decoding for dirty paper coding (DPC) in the high signal-to-noise ratio (SNR) regime. We divide the channel code into two levels, the upper code interacting with the shaping code and the lower code that does not such that it is information lossless. Our code design is more intuitive for designing DPC in the high SNR regime. The design of the lower code becomes trivial since it does not interact with the shaping code anymore. The design of the upper code is also simplified since we can now assume binary signaling for the code. We evaluate the capacity of each level and design codes to approach the estimated capacity. We demonstrate a good performance can indeed be achieved by simulations using low- density parity-check (LDPC) codes at each level. Our best code is only 0.45 dB from the no-interference Gaussian capacity at the spectral efficiency of 3 b/s/Hz.

Duprat and Muller (IEEE trans. Computers, vo1.42. no. 2, p. 168-178, Feb. 1993) introduced the ingenious "Branching CORDIC" algorithm. It enables a fast implementation of CORDIC algorithm using signed digits and requires a constant normalization factor. This correspondence corrects some errors in the original paper.

In the original paper (G.A. Dumont, I.M. Jonsson, M.S. Davies, F.T. Ordubadi, Y. Fu, K. Natarajan, C. Lindeborg, and E.M. Heaven, ibid., vol. 1, p. 101-13, 1993), it is assumed that the sample time is the same and constant for each cross machine position. The author asserts that in fact the first cross-directional point, i.e. the point at the edge of the paper sheet, alternates between sample times of zero and twice the scan time. It is concluded that the moisture estimates could be further improved by using a model with 2N "positions", where there are N cross-directional measurement point. >

Multiuser diversity has attracted significant attention recently. In this letter, we propose a greedy algorithm based on QR decomposition of the channel and dirty paper precoding to exploit the multiuser diversity of the Gaussian vector broadcast channel. Simulations show the approach provides performance which is extremely close to a well-known upper bound on the sum rate. Further, exploiting multiuser diversity can provide large gain over approaches ignoring this resource.

A dynamic model for basis weight variations in paper machines is established and estimated recursively from scanned measurements using a combination of an exponential forgetting and resetting least squares estimator and an extended Kalman filter. The algorithm provides online estimation of basis weight variations in both cross-machine direction and machine direction, as well as estimates of the dynamic parameters and noise characteristics of the process. >

It is pointed out that the Bernard estimator is very accurate, with respect to other median or mean approximated ranks, confirming results presented by J.C. Fothergill in the above-titled paper (see ibid., vol.25, p.489-92, 1990). However, it is argued that the weighted Blom seems the most accurate estimator, among graphical ones, for normally sized samples and a reliable one for small sample sizes, although the Bernard and Filliben estimators are better than Weibull and Blom for small sample sizes. Statistical and graphical estimators are compared by plotting the percent deviations of the values of the Weibull parameters alpha and beta (scale and shape parameters, respectively) estimated by weighted Blom, Bernard, Weibull, maximum likelihood estimation (MLE), and Bain-Engelhardt (BE), with respect to the true values, as well as the estimates obtained by MLE and BE, as functions of the sample size. In replying, Fothergill states that for small sample sizes, the advantages of more sophisticated techniques do not seem warranted. >

O. Moreno and P.V. Kumar (IEEE Trans. Inform. Theory, vol.39, no.5, September 1993) showed how Deligne's theorem can be applied to coding theory. They studied certain subcodes of binary Reed-Muller codes and estimated the associated character sums over a field of q/sup 2/ elements. They obtained bounds of the order /spl Oscr/(q). The present paper shows that in one case one can improve the coefficient of q in the estimates. The author also shows that there is an error in Moreno and Kumar's argument and in some cases one needs need to replace a bound of the order /spl Oscr/(q) by a weaker bound of the order /spl Oscr/(q/sup 3/2/). >

This paper discusses the comments of David de Wolf on the paper [1]. In his comments, Dr. De Wolff recalls the possibility of also using Shanks acceleration for improving convergence. But all this is rather anecdotic. The relevant thing is to have at hand as many acceleration techniques as possible (summation by parts, weighted averages, Euler, Kummer, Abel, Ewald, Levin, Richardson, Aitken/Shanks/Wynn, etc), and to use the most adequate to each situation

The electromagnetic boundary value problem of two waveguides coupled by an aperture or an aperture in a waveguide radiating into free space may be described by an integral equation. An analytical solution to this integral equation cannot be readily found due to the complexity of the kernel. However, extremely useful results may be obtained if the method of moments is employed to reduce the integral equation to a matrix equation which can be solved by known methods. In this short paper, series and shunt slots in a rectangular waveguide are analyzed using this technique.

A channel with output Y = X + S + Z is examined, The state S \sim N(0, QI) and the noise Z \sim N(0, NI) are multivariate Gaussian random variables ( I is the identity matrix.). The input X \in R^{n} satisfies the power constraint (l/n) \sum_{i=1}^{n}X_{i}^{2} \leq P . If S is unknown to both transmitter and receiver then the capacity is \frac{1}{2} \ln (1 + P/( N + Q)) nats per channel use. However, if the state S is known to the encoder, the capacity is shown to be C^{\ast} =\frac{1}{2} \ln (1 + P/N) , independent of Q . This is also the capacity of a standard Gaussian channel with signal-to-noise power ratio P/N . Therefore, the state S does not affect the capacity of the channel, even though S is unknown to the receiver. It is shown that the optimal transmitter adapts its signal to the state S rather than attempting to cancel it.

In this paper, we consider a general K-user Gaussian multiple-input multiple-output (MIMO) broadcast channel (BC). We assume that the channel state is deterministic and known to all the nodes. While the private-message capacity region is well known to be achievable with dirty paper coding (DPC), we are interested in the simpler linearly precoded transmission schemes. In particular, we focus on linear precoding schemes combined with rate-splitting (RS). First, we derive an achievable rate region with minimum mean square error (MMSE) precoding at the transmitter and joint decoding of the sub-messages at the receivers. Then, we study the achievable sum rate of this scheme and obtain two findings: 1) an analytically tractable upper bound on the sum rate that is shown numerically to be a close approximation, and 2) how to reduce the number of active streams -- crucial to the overall complexity -- while preserving the sum rate to within a constant loss. The latter results in two practical algorithms: a stream elimination algorithm and a stream ordering algorithm. Finally, we investigate the constant-gap optimality of linearly precoded RS with respect to the capacity. Our result reveals that, while the achievable rate of linear precoding alone can be arbitrarily far from the capacity, the introduction of RS can help achieve the capacity region to within a constant gap in the two-user case. Nevertheless, we prove that the RS scheme's constant-gap optimality does not extend to the three-user case. Specifically, we show, through a pathological example, that the gap between the sum rate and the sum capacity can be unbounded., This paper is accepted for publication in the IEEE Transactions on Information Theory. This paper is the revised version of "Linearly Precoded Rate Splitting: Optimality and Non-Optimality for MIMO Broadcast Channels"

This paper proposes an application of the boundary-element method to two-dimensional electromagnetic field problems. By this method, calculations can be performed using far fewer nodes than by the finite-element method, and unbounded field problems are easily treated without special additional consideration. In addition, the results obtained have fairly good accuracy. In this paper, analyzing procedures of electromagnetic field problems by the boundary-element method, under special conditions, are proposed and several examples are investigated.

In this note we first point out some simplifications in some results of our paper mentioned above [1]. Second, we prove that the algebra of transfer functions \hat{\cal B}(\sigma_0) , introduced in the paper, is in fact the quotient ring of the ring \hat{\cal Q}_{_}(\sigma_0) with respect to the multiplicative system \hat{\cal Q}_{_}^{\infty} (\sigma_0) defined in this note. The analogy between \hat{\cal B}(\sigma_0) , seen as the quotient [\hat{\cal Q}_{_}(\sigma_0)][\hat{\cal Q}_{_}^{\infty} (\sigma_0)]^{-1} , and the algebra of proper rational functions C_p (s) seen as the quotient [\Re (\sigma_0)][\Re^{\infty} (\sigma_0)]^{-1} (where \Re_0 (\sigma_0 ) is the ring of proper rational functions analytic in Re s \geq \sigma_0 , and \Re^{\infty} (\sigma_0) is the multiplicative system of such functions tending to a nonzero constant as |s| \irightarrow \infty ), is fully developed and supports the claim that \hat{\cal B} (\sigma_0 ) is a natural extension of the algebra of proper rational functions to distributed systems. These algebraic developments have been found most useful in applications [11], [12].

The author makes various observations on Albert Einstein's short note of 1914 ["Method for the determination of the statistical values of observations concerning quantities subject to irregular fluctuations," Arch. Sci. Phys. et Natur., 37, ser. 4, 254-56 (1914)] on methods of reducing fluctuating series of observations. He argues that it foreshadows the theory behind the Fast Fourier Transform (FFT). The paper seems not to have attracted much attention when it was given, and was soon nearly forgotten. In any case, the present author has found no reference to it, either in a bulky index of literature on the theory of time series or in the tens of monographs, symposia and detailed reviews on this topic that he has examined. Only in 1979, in connection with the worldwide observance of the Einstein centenary, did the East German H. Melcher draw attention to the existence of the little-known paper (without discussing its content).

It is shown that if the expanded node three-dimensional TLM method is operated in a certain way, then it can be numerically equivalent to a finite-difference method. Some comments are made on comparisons between the two approaches.

This short paper presents a general computer analysis of gradually tapered waveguide with arbitrarily shaped cross sectious. The technique combines coupled-mode theory with numerical methods for solving the uniform waveguide problem. The coupling coefficients are computed by using eigenvalues and eigenfunctions obtained numerically. The mode amplitudes are obtained either by numerical solution of a set of differential equations or from a closed-form solution. The applicability of this technique is illustrated by the analysis and measurement of two transitions. It is shown that theoretical prediction of coupled-mode amplitudes is reliable for gradual tapers where the flare angle is small. For large flare angles, more rigorous coupled-mode theory has to be employed.

Exact transverse electric and magnetic mode solutions of four triangular cross-section waveguides have been found via a new general method using Snell's law and superposition of plane waves. This paper presents results for 1) equilateral, 2) 30°, 30°, 120°, 3) isosceles right, and 4) 30°, 60° right triangular waveguides. The electric and magnetic field solutions form finite sums of separable rectangular harmonics and are the only waveguides of triangular cross section for which such solutions have been found.

The purpose of this short paper is to construct the dissipation and scattering matrices of lossy junctions in terms of the eigenvalues of the dissipation matrix. This removes the need to rely on inequality relations between the scattering parameters of lossy circulators. The eigenvalues of the dissipation, scattering, and admittance matrices are related. The eigenvalues of the dissipation matrix give the dissipation associated with each possible way of exciting the junction. The ones of the scattering matrix give the reflection coefficients associated with these different excitations. The admittance eigenvalues define in each instance the eigennetworks of the junction. This leads to the definition of the entries of the dissipation matrix in terms of the loaded and unloaded Q-factors of the junction eigennetworks. The scattering matrices of a number of lossy 3-port junctions are also constructed directly in terms of the elements of the eigennetworks.

Using the Frankel-Young method, fast estimation of the potential distribution for a microstrip structure is obtained when an accelerating factor /spl omega/ is introduced in the finite-differences (relaxation) method. It is possible to calculate such a factor by an iterative technique, but the time of computation needed to find /spl omega/ annihilates the theoretical gain. In this short paper, the authors present a method which gives an analytical expression for /spl omega/. The realistic case examined here, as an illustration, is that of the suspended microstrip couplers for which odd and even impedances are the interesting parameters. Given an analytical expression for /spl omega/, the overrelaxation method appears as a very powerful and attractive method for finding the solution of any type of microstrip structure.