Comments on “Improved Sufficient Conditions for Global Asymptotic Stability of Delayed Neural Networks”

In this note, we point out that the results given in the paper by Wu and Cui (2007) can be obtained by using the results given in Lu (2003). Moreover, the results given in the second paper are much stronger under less restrictive conditions.      

Comments on “A Hierarchy of Importance Indices”

The paper by Hwang (IEEE Trans. Reliability, vol. 54, pp. 169–172, 2005) presented structural importance measures in terms of cutsets or pathsets, and investigated how they are related. Hwang's paper has made contributions to importance measures. However, several errors which cause confusions are found in the paper. This note is to clarify these errors, and discuss the suspicions.      

Comments on “Stability Analysis of a Class of Nonlinear Fractional-Order Systems”

It has been pointed out that the numerical simulation results presented in the above paper are not consistent with reality. The reason for this inconsistency has analytically been clarified in this note.     

Comments on “On the Self-Generation of Electrical Soliton Pulses”

A recent paper on soliton oscillators gave a parsimonious account of earlier work and omitted a critical reference.     

Comments on “Phase-Shifting for Nonseparable 2-D Haar Wavelets”

In their recent paper, Alnasser and Foroosh derive a wavelet-domain (in-band) method for phase-shifting of 2-D “nonseparable” Haar transform coefficients. Their approach is parametrical to the (a priori known) image translation. In this correspondence, we show that the utilized transform is in fact the separable Haar discrete wavelet transform (DWT). As such, wavelet-domain phase shifting can be performed using previously-proposed phase-shifting approaches that utilize the overcomplete DWT (ODWT), if the given image translation is mapped to the phase component and in-band position within the ODWT.      

Comments on “Bandpass Sigma-Delta Modulator Employing SAW Resonator as Loop Filter”

Some corrections needed in the theoretical analysis of the surface acoustic wave resonator loop filter for a bandpass sigma-delta modulator, as presented by Yu and Xu, are pointed out. A simple idea is also proposed for perfect cancellation of anti-resonance without substantially affecting the resonance frequency, but with the added benefits of an enhanced factor and insertion gain, rather than insertion loss. However, a practical implementation of the idea remains an open question.     

Comments on “Study of the Complex Atomic Susceptibility of Erbium-Doped Fiber Amplifiers”

This comment aims to report and correct a mistake in the paper by Desurvire (J. Lightw. Technol., vol. 8, no. 10, pp. 1517-1527, Oct. 1990) with regard to the expression of the complex susceptibility of quasi-three-level laser systems. The derived susceptibility formula contradicts the assumption of thermal equilibrium between sublevels within each manifold and leads to the wrong conclusion that the real and imaginary parts of the susceptibility of saturated materials do not verify the Kramers-Kronig relations (KKR). The corrected formula for the susceptibility is hereby proposed. The poles of the susceptibility obtained with the new formula are all located in the upper half plane of the complex plane, in accordance with the principle of causality. Hence, the KKR should be valid in the saturated regime.     

Comments on “Analysis of the Bridged T-coil Circuit Using the Extra-Element Theorem”

In contrast to the use of the extra-element theorem, it is shown that a much simpler analysis is possible of the bridged T-coil bandwidth enhancement circuit by classical techniques.     

Comments on “Beam Quality Factor of Higher Order Modes in a Step-Index Fiber”

In a previously published paper [1], equations are presented that predict the beam-quality factor of beams from multimode fibers. We demonstrate that the simplification made in these equations to generate several of the figures is incorrect and that these formulas cannot be generally simplified for beams that are coherent superpositions of modes.     

Comments on “Optimal Erasure Protection for Scalably Compressed Video Streams With Limited Retransmission”

In order to prove a key result for their development (Lemma 2), Taubman and Thie need the assumption that the upper boundary of the convex hull of the channel coding probability-redundancy characteristic is sufficiently dense. Since a floor value for the density level for which the claim to hold is not specified, it is not clear whether their lemma applies to practical situations. In this correspondence, we show that the constraint of sufficient density can be removed, and, thus, we validate the conclusion of the lemma for any scenario encountered in practice.      

Comments on “Dynamic Routing of Restorable Bandwidth-Guaranteed Tunnels Using Aggregated Network Resource Usage Information”

This paper identifies and corrects two flaws in the paper ldquoDynamic routing of restorable bandwidth-guaranteed tunnels using aggregate network resource usage informationrdquo, Kodialam and Lakshman, IEEE/ACM Trans. Networking, 2003.     

Comments on “Semi-Blind Channel Estimation and Equalization for MIMO Space–Time Coded OFDM”

A semiblind channel estimation scheme of the multiple-input–multiple-output space–time coded orthogonal frequency-division multiplexing system was proposed in the aforementioned paper for either real or complex with symmetric signals. We point out that this scheme cannot work correctly for complex signal scenario.      

Comments on “High Performance Inversion-Type Enhancement-Mode InGaAs MOSFET With Maximum Drain Current Exceeding 1 A/mm”

We have a number of issues with the above paper ldquoHigh Performance Inversion-Type Enhancement-Mode InGaAs MOSFET With Maximum Current Exceeding 1 A/mm,rdquo by Y. Xuan, Y. Q. Wu, and P. D. Ye, published IEEE Electron Device Letters in April 2008 which we wish to highlight.     

Comments on “power controlled channel allocation for multiuser multiband UWB systems“

In this note, two typos in above-mentioned paper are pointed out and a sufficient condition to ensure the PER requirement in the optimization problem is provided.     

Repeat Bidding on Internet-Based Multiple-Item “Name-Your-Own-Price” Auctions

Name-Your-Own-Price (NYOP) auctions have gained recent popularity on the Internet. In many NYOP settings, the auction firm displays multiple bidding items for the bidders (such as multiple options of airline tickets) and restricts them to place a single offer. Recent studies have, however, shown that the Internet environment enables many customers to engage in repeat bidding. Our purpose in this paper is: 1) to analyze the consumer value gained by repeat bidding on multiple-item NYOP auctions under different-bidding strategies; 2) to derive an upper bound on the value gained by repeat bidding when multiple items are present; and 3) to analyze the multiple-item NYOP auction from a consumer-firm perspective. We use Monte Carlo simulation to discuss the effects of various auction parameters on the firm's expected profit, and show that the presence of multiple bidding items provides a win–win situation for both the auction firm and the bidders. In particular, we show that multiple items increase the expected value for the consumers and also help firms mitigate potential losses due to repeat bidding.      

A “Flying-Adder” On-Chip Frequency Generator for Complex SoC Environment

The spirit of system-on-chip (SoC) approach is to integrate more and more system functions into one single chip. Consequently, the on-chip clock requirement could be very complicated due to the various functions the chip has to support. To fulfill those clock needs, it is not uncommon for more than several phase-locked loop (PLLs) to be used within one such large chip. Designing these on-chip PLLs is a very challenging task in term of cost and performance. To solve this problem for a HDTV SoC of over 50 millions transistors, a ldquoflying-adderrdquo architecture based PLL (FAPLL) is constructed. This generic FAPLL is instantiated multiple times in this SoC for different functions, resulting in significant chip cost reduction.     

Improvement on “Sequential Testing” in MIL-HDBK-781A and IEC 61124

This paper presents results of an analysis of the sequential test (ST) procedures described in MIL-HDBK-781A, and IEC 61124, intended for checking the mean Time Between Failures (TBF) value under an exponential distribution of the TBF. The methodological basis of the calculations consists in discretization of the ST process through subdivision of the time axis in small segments. By this means, the process is converted into a binomial for which an algorithm, and a fast computer program have been developed; and most important of all, a tool is provided for searching for the optimal truncation. The influence of truncation by time on the Expected Test Time (ETT) characteristics was studied; and an improved truncation method, minimizing this influence, was developed. The distributions of the test times were determined. The type A plan characteristics in IEC 61124:2006 have substantial inconsistencies in the probabilities of types I & II errors (up to a factor of 2), and in the ETT (up to 17%). We checked these results by using the binomial-recursive method, and by simulation. The Type C plans, reproduced from GOST R27.402:2005, are consistent; but there is scope (and need) for substantial improvement of the search algorithm for the optimal parameters.     

A Piezo-Sensor-Based “Smart Tire” System for Mobile Robots and Vehicles

In this paper, we present the development of a tire rubber deformation sensing system that provides the critical information for understanding and estimation of wheel/ground interactions for mobile robots and vehicles. Polyvinylidene fluoride (PVDF)-based sensors are designed and fabricated to embed on the inner tread surface to measure the tire rubber tread deformation. Analytical models of the PVDF-based sensing system are presented to capture the wheel/ground contact information and friction characteristics. The sensed deformation measurements are integrated with the onboard control system through a wireless data transmission module. Experimental results on a skid-steered mobile robot are presented to show the feasibility and estimation of wheel/ground friction characteristics using the developed sensing system.     

Digital Background-Calibration Algorithm for “Split ADC” Architecture

The “split ADC” architecture enables continuous digital background calibration by splitting the die area of a single ADC design into two independent halves, each converting the same input signal. The two independent outputs are averaged to produce the ADC output code. The difference of the two outputs provides information for a background-calibration algorithm. Since both ADCs convert the same input, when correctly calibrated, their outputs should be equal, and the difference should be zero. Any nonzero difference provides information to an error-estimation algorithm, which adjusts digital-calibration parameters in an adaptive process similar to a least mean square algorithm. This paper describes the calibration algorithm implemented in the specific realization of a 16-bit 1-MS/s algorithmic cyclic ADC. In addition to correcting ADC linearity, the calibration and estimation algorithms are tolerant of offset error and remove linear scale-factor-error mismatch between the ADC channels. Simulated results are presented confirming self-calibration in approximately 10 000 conversions, which represents an improvement of four orders of magnitude over previous statistically based calibration algorithms.      

The “Bayesian Anomaly” and Its Practical Mitigation

A fundamental logical problem in the Bayesian inference of a series system's failure probability is described, a practical means for its mitigation is discussed, and its application to space launch vehicles is illustrated. The problem is the ldquoBayesian Anomaly,rdquo the difference in the system's failure probability per operation inferred from prior estimates, and test or operational experience applied at a lower-level of the system; and from the convolution of the same priors, and of the same experience applied at the system level (or any level above the first). In particular, unlike in a classical inference, the mean estimates differ critically. Although it is not possible to entirely resolve the problem, a practical procedure for mitigating it, establishing consistency among the mean and variance estimates at the two levels, is delineated.