Comments on “A deterministic approach to the end-to-endanalysis of packet flows in connection oriented networks”

For original paper see Chlamtac et al. (IEEE/ACM Trans. Networking, vol.6, no.4, p.422-31, 1998 August). We prove that the buffer bound in the above paper, can be improved by using a modification of the proofs in the original paper together with so-called network calculus bounds. We also show that the delay bound in the above paper, is the sum of worst-case queueing delays at all nodes along the path of a connection     

Comments on a “A neural network approach to MVDR beamformingproblem”

Several corrections to the above-titled paper by P.R. Chang et al. (ibid, vol. 40, pp 313-322, 1992) are given by the commenter, who also discusses a number of Chang et al.'s results. The commenter also discusses the practical issues that arise when an array operates in a nonstationary environment     

Comments on “A neural network compensator for uncertaintiesof robotics manipulators”

It is shown in this letter that the function of the neural network compensator proposed in the original paper is redundant. Perfect rejection of both structured and unstructured uncertainties in the robot dynamic model can be achieved directly without the compensator     

Comments on “modified K-means algorithm for vector quantizerdesign”

Previously a modified K-means algorithm for vector quantization design has been proposed where the codevector updating step is as follows: new codevector=current codevector+scale factor (new centroid-current codevector). This algorithm uses a fixed value for the scale factor. In this paper, we propose the use of a variable scale factor which is a function of the iteration number. For the vector quantization of image data, we show that it offers faster convergence than the modified K-means algorithm with a fixed scale factor, without affecting the optimality of the codebook.     

Comments on “New dynamic flip-flops for high-speeddual-modulus prescaler”

For the original paper see ibid., vol. 33, no. 10, p. 1568-1571 (1998). In the aforementioned paper a fast true single-phase clocking (TSPC) ratioed D-flip-flop is proposed by C. Yang et al. It is claimed by the commenters that the proposed flip-flop violates the edge-triggering characteristic. However, it is shown that high clock frequency and the propagation delay of the transistor enable the flip-flop to operate normally in the dual-modulus prescaler     

Comments on “A comparison of two quantized state adaptivealgorithms”

The author presents a correction to an error in the paper of W.A. Sethares and C.R. Johnson (see IEEE Trans. Acoust. Speech Signal Processing, vol.37, no.1, p.138, Jan. 1989). A comparison is carried out between the quantized error (QE) and the quantized regressor (QReg) algorithms in the paper by Sethares and Johnson. However, an error in Theorem 1 leads to incorrect conclusions about the performance of the QE algorithm when using a quantizer with a dead zone     

Comments on “A tabulation of Hilbert transforms forelectrical engineers”

A new table of Hilbert transforms was prepared and published by Alavi-Sereshki and Prabhakar (see ibid., vol.COM-20, no.6, p.1194, 1972). During preparation, it was found that some formulas in the above paper were in error. Therefore, the tables in that should be used with great care. Correct Hilbert transform pairs are presented by Hahn (1996). The Hilbert transform of an amplitude-modulated signal, given in the above paper, as the infinite sum of quotients of integrals, is derived in compact form     

Comments on “A CMOS ratio-independent and gain-insensitivealgorithmic analog-to-digital converter”

For the original paper see ibid., vol. 31, no. 8, p. 1201-1207 (1996). The commenter points out some errors in the aforementioned paper and provides the necessary corrections     

Comments on “Shielding effectiveness of conductivepolymers”

The authors comment that K. Naishadham (see ibid., vol.34, no.1, p.47-50, 1992) calculated the plane-wave shielding effectiveness of conductive polymers as a function of frequency. As indicated, a comparison to the measured result of the DC conductivity indicates that the microwave conductivity at room temperature is within a small percentage of the DC result, and therefore can be used for a wide frequency range. The conductivity of the polymers is given by σ=2πf₀ϵ₀ϵ" and is assumed invariant for all frequencies. Based on the invariability of polymers' conductivity for all frequencies, they calculated the shielding effectiveness of the polymers. Discrepancies are found by comparing these figures to those of Naishadham. It is concluded that shielding effectiveness calculated by Naishadham was done under the assumption of frequency-invariant ϵ" instead of σ     

Comments on “Comments on the peak factor of sampled andcontinuous signals”

The author comments that a signal, which does not satisfy the conditions of the sampling theorem, is used as a basis for the proof in the paper of Wulich (see ibid., vol.4, no.7, p.213-14, 2000). Therefore, the presented proof is incorrect     

Comments on “A new model of generalized inverter and itsapplications”

For the original paper see ibid., vol. 45, no. 1. p. 132-5 (1997). The commenter considers that the generalized impedance inverter described in the aforementioned paper with associated theory is essentially identical to that published by him previously (see ibid., vol. 21, no. 8, p. 519-26, 1973)     

Comments on “A new edge element analysis of dispersivewaveguiding structures”

For original paper see J. Tan and G. Pan, ibid., vol.43, no.11, pp.2600-7 (1995). Tan and Pan stated that certain analytical methods cannot be directly applied to transmission lines with finite thickness and finite conductivity because of the appearance of spurious modes. The authors contest this statement, and Pan and Tan reply to their comments     

Comments on “A Combined Code Acquisition and Symbol Timing Recovery Method for TDS-OFDM”

For original paper see Wang et al. (IEEE Trans. Broadcast., vol.49, no.3, p.304-8, 2003 September). In this correspondence, the shortcomings of the proposed algorithms in the above paper are analysed in detail. It is shown by the analysis that the algorithms are practically problematic     

Comments on “Radial line planar monopulse antenna”

The author points out that Miyashita and Katagi (IEEE Trans. Antennas Propagat., vol.44, p.1158-65, Aug. 1996) claim a new type of planar monopulse antenna, without reference to Kelly and Goebels (1964) that described their “invention” of the radial line planar monopulse antenna. Further, scant mention is made of the pioneering work by Goebels and Kelly (1961) and by Kelly and Goebels (1964) in various other papers by Goto, Ando, Nakano and others     

Comments on “Nonblocking property of reverse banyannetworks”

It is shown that the nonblocking property of reverse banyan networks mentioned in the above paper follows directly from the fact that banyan networks can realize permutations characterized by bitonic sequences     

Comments on “transient radiation of traveling-wave wireantennas”

Wu and Ruan (see ibid., vol.41, p.120-23, 1999), based on the formalism of Podosenov, Svckis and Sokolov (1995), tried to calculate the electromagnetic radiation field from the current of a traveling wave propagating along a thin curvilinear wire with free ends. In this article the author tries to prove that in the paper of Wu et al. one problem was substituted by another. In fact, another problem, but not that which was formulated by the authors, was solved. It is not the problem of radiation from a curvilinear antenna of finite length, but the problem of radiation from part of an infinite antenna and two external sources emerging under a forcible requirement of satisfying the Lorentz condition for a subsystem, where this condition does not operate a fortiri. The proof is based on the following easily verifiable facts: (1) a coincidence of the expressions for the magnetic field; and (2) a dissimilarity of the expression for the electric field from the formula to a forcible imposing of the Lorentz condition being invalid for subsystems. The author comments on the second point in more detail     

Comments on “Further improvements in digitizingcontinuous-time filters”

This correspondence points out that an algorithm proposed by C. Wan and A.M. Schneider (see ibid., vol.45, no.3, p.533-42, March 1997) as a new digitizing method is, in fact, an extension of the linear interpolation design. Unlike previously published extensions, which incorporate the interpolation step into the s- to z-domain mapping step, this algorithm cascades the interpolator and the analog filter. Original design formulas derived for a rigorous comparison support the assertion that the above algorithm yields less accurate results than the other interpolation designs     

Comments on “Partial parallel interference cancellation forCDMA”

We comment on partial parallel interference cancellation as discussed in the paper by Divsalar et al. (see ibid. vol.46, p.258-68, 1998). The aforementioned work showed that by multiplying the symbol estimates by a factor less than unity in the early stages of cancellation, the performance of parallel cancellation can be improved relative to full (“brute force”) cancellation. In this paper we analyze the improvement of parallel cancellation when using partial cancellation, and provide additional insight into the gains. Specifically, we show that the decision statistic is biased when linear (soft) estimates of the symbol or channel are used for cancellation. Partial cancellation improves the performance in this case by reducing the decision statistic bias