Fast Recovery Blind Equalization for Time-Varying Channels Using “Run-and-Go” Approach

In this paper, we propose a blind adaptive equalization scheme for time-varying channels, which combines a blind algorithm based on high order statistics (HOS) and decision-directed (DD) LMS algorithm. In contrast to the ldquostop-and-gordquo algorithm , where DD-LMS adaptation is stopped for unreliable decisions, the proposed algorithm applies a blind algorithm based on HOS for the unreliable decisions. Furthermore, the region of reliable decisions is updated corresponding to the estimated signal quality. Hence, the proposed ldquorun-and-gordquo algorithm inherits MMSE performance of DD-LMS and the (re)acquisition ability of the blind algorithm. Especially, for decision feedback equalizers (DFEs) the proposed algorithm provides robust blind initialization and reacquisition ability under time varying multipath environments.     

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.     

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.      

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.      

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.      

An Erbium Fiber Fabricated by the “Core-Suction” Technique

An erbium doped fiber preform having a lead germanate erbium glass core with silica cladding was fabricated by a newly developed technique named “Core-Suction”. This preform was then drawn into fiber and fiber cross-section, loss spectrum and refractive index profile measured. A 30 cm piece of the manufactured fiber was spliced to a standard silica fiber using a commercial available splicer. This spliced fiber was then used to setup an erbium doped fiber amplifier (EDFA) and gain spectrum of the amplifier measured. Distributed gain of the manufactured erbium fiber was measured using an optical frequency domain reflectometry (OFDR) based optical backscatter reflectometer (OBR). It is demonstrated that the “Core-Suction” technique can be used to make a high-gain amplifier that is compatible with conventional silica fibers.      

Comments on “A Class of Fault-Tolerant Multiprocessor Networks”

A. Ghafoor presented node-disjoint paths of even networks using Figs. 4, 5, 6,and 7 (Ghafoor, IEEE Trans. Reliability, vol. 38, no. 1, pp. 5-15). However, the paper contains errors which cause confusion. We show that the node-disjoint paths, and Theorem 4 (Ghafoor, IEEE Trans. Reliability, vol. 38, no. 1, pp. 5-15), are not correct. We propose advanced node-disjoint paths, and prove that the fault diameter of even networks is d+1. This is optimal.     

Field Experiment on a “Star Type” Metropolitan Quantum Key Distribution Network

Quantum key distribution (QKD) networks have recently attracted growing attention. The topology of the local QKD network is the basis of the next-generation global secure communication network. In this letter, we report a realization of a wavelength-routing star type QKD network which can span a metropolis using a commercial backbone optical fiber network without trusted relays. The longest and the shortest fiber lengths between two geographically separated nodes are 42.6 and 32 km, respectively, and the maximum average quantum bit-error rate is below 8%. A novel analysis model with experimental validation is also proposed to evaluate the user's performance in this network under the condition of maximum multiuser crosstalk.     

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.     

“Shopping” for a Mate: Expected versus Experienced Preferences in Online Mate Choice

Modern communication technology has greatly increased the number of options we can choose among in a variety of evolutionarily important domains, from housing to food to mates. But is this greater choice beneficial? To find out, we ran two experimental studies to examine the effects of increasing option set-size on anticipated and experienced choice perceptions in the modern context of online mate choice. While participants expected greater enjoyment, increased satisfaction, and less regret when choosing from larger (versus smaller) sets of prospective partners (at least up to a point; Study 1), participants presented with a supposedly ideal number of options experienced no improvement in affect and showed more memory confusions regarding their choice than did those participants presented with fewer options (Study 2). Participants correctly anticipated that greater choice would yield increasing costs, but they overestimated the point at which this would occur. We offer an evolutionary-cognitive framework within which to understand this misperception, discuss factors that may make it difficult for decision-makers to correct for it, and suggest ways in which dating websites could be designed to help users choose from large option sets.     

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 “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.      

Wafer-Level Defect Screening for “Big-D/Small-A” Mixed-Signal SoCs

Product cost is a key driver in the consumer electronics market, which is characterized by low profit margins and the use of a variety of “big-D/small-A” mixed-signal system-on-chip (SoC) designs. Packaging cost has recently emerged as a major contributor to the product cost for such SoCs. Wafer-level testing can be used to screen defective dies, thereby reducing packaging cost. We propose a new correlation-based signature analysis technique that is especially suitable for mixed-signal test at the wafer-level using low-cost digital testers. The proposed method overcomes the limitations of measurement inaccuracies at the wafer-level. A generic cost model is used to evaluate the effectiveness of wafer-level testing of analog and digital cores in a mixed-signal SoC, and to study its impact on test escapes, yield loss, and packaging costs. Experimental results are presented for a typical mixed-signal “big-D/small-A” SoC, which contains a large section of flattened digital logic and several large mixed-signal cores.      

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.     

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.     

Application of the “Contact Convoy” Concept to Hybrid Electric Vehicles

This paper applies an intelligent intervehicle device (termed a ldquobridging damperrdquo) to a convoy of in-contact vehicles. The field of application is backup for future automated highways and operation of novel guided systems using vehicle-following control. The vehicle represented in computer simulations is a parallel hybrid electric automobile. Using the advanced vehicle simulator (ADVISOR) model, the vehicle representation is tuned to achieve matching of the overall force and power characteristics and the same performance over an urban driving cycle. The model for which a dedicated Matlab Toolbox was constructed is described. Simulation results compare the vehicle-following control on its own with a passive damper and a ldquoquasi-activerdquo damper that is controlled in collaboration with the vehicle's drivetrain. Using transient disturbances in the form of wind gusts and short gradients, power peaks and longitudinal ride quality (vibration dose value) are used to evaluate the performance.