A 21-mW 8-b 125-MSample/s ADC in 0.09-mm/sup 2/ 0.13-/spl mu/m CMOS

This paper presents an 8-b two-step subranging analog-to-digital (ADC) using interpolation, averaging, offset compensation, and pipelining techniques to accomplish an effective number of bits of 7.6 b at 125 MSample/s. The 0.13-/spl mu/m CMOS ADC occupies 0.09 mm/sup 2/ and consumes 21 mW.     

Doppler spread estimation in mobile radio systems

In this letter, Doppler spread estimation in digital mobile radio systems is described. A maximum-likelihood approach is derived, and used to develop suboptimal approaches with lower complexity. The proposed algorithms rely on periodic channel estimation and can be used in both TDMA and CDMA systems     

DWAM — A WAM model extension for disjunctive logic programming

Answering queries in disjunctive logic programming requires the use of ancestry-resolution. The resulting complication makes it difficult to implement a Prolog-type query answering procedure for disjunctive logic programs. However, SLO-resolution provides a mechanism which is similar to SLD-resolution and hence offers a solution to this problem. The Warren Abstract Machine has been a very effective model for implementing Prolog. In this paper, we extend the WAM model of Prolog and adapt it for DISLOG — a language for disjunctive logic programming. We describe the extensions and additional instructions needed to make WAM viable for modeling and executing DISLOG. The extension is made in such a way that the original architecture is not disturbed and a Prolog program will execute as efficiently as it does in the original WAM.This work was done while the author was at the University of Kentucky.     

The strain hardening rotating hollow shaft subject to a positive temperature gradient

Summary The modeling of deformation in flexible multibody systems is still under intensive investigation. While the floating frame of reference formulation has become a standard for the modeling of deformable moving bodies, formulations based on absolute coordinates are comparatively new. The recently developed absolute nodal coordinate formulation uses solely nodal position and slopes as degrees of freedom for structural elements. The numerical treatment is similar to the absolute coordinate formulation, which is investigated in the following. An efficient formulation based on absolute coordinates with a reduced strain tensor (similar to corotational formulations) has been derived recently, and the analogy to the floating frame of reference formulation has been shown. The efficiency of this formulation is based on a co-rotated stiffness matrix which is factorized only once, however, only linear constraints have been treated up to now. The present paper treats the extension of the advantages of the co-rotated formulation with respect to nonlinear constraints, damping and contact. Constraints are discussed for the special cases of linear and nonlinear dependence on the deformation degrees of freedom. The (implicit) Newmark scheme is used to illustrate the time stepping procedure within the present method. In the case of a small number of nonlinear constraints, a single time step can be performed by solving only a small system of nonlinear equations by means of Newton's method. A numerical example shows a method to reduce the number of constraints and illustrates the computational advantages of the proposed method.     

Speech perception test in Italian language for profoundly deaf children

Speech perception tests are an important part of procedures for diagnosing pre-verbal hearing loss. Merely establishing a child's hearing threshold with and without a hearing aid is not sufficient to ensure an adequate evaluation with a view to selecting cases suitable for cochlear implants because it fails to indicate the real benefit obtained from using a conventional hearing aid reliably. Speech perception tests have proved useful not only for patient selection, but also for subsequent evaluation of the efficacy of new hearing aids, such as tactile devices and cochlear implants. In clinical practice, the tests most commonly adopted with small children are: The Auditory Comprehension Test (ACT), Discrimination after Training (DAT), Monosyllable, Trochee, Spondee tests (MTS), Glendonald Auditory Screening Priocedure (GASP), Early Speech Perception Test (ESP), Rather than considering specific results achieved in individual cases, reference is generally made to the four speech perception classes proposed by Moog and Geers of the CID of St. Louis. The purpose of this classification, made on the results obtained with suitably differentiated tests according to the child's age and language ability, is to detect differences in perception of a spoken message in ideal listening conditions. To date, no italian language speech perception test has been designed to establish the assessment of speech perception level in children with profound hearing impairment. We attempted, therefore, to adapt the existing English tests to the Italian language taking into consideration the differences between the two languages. Our attention focused on the ESP test since it can be applied to even very small children (2 years old). The ESP is proposed in a standard version for hearing-impaired children over the age of 6 years and in a simplified version for younger children. The rationale we used for selecting Italian words reflect the rationale established for the original version, but the choice of single words follows different criteria from the original version. In fact, the two languages differ in important linguistic features so that the test can not be not adapted to the Italian language by simply translating the words involved. As currently there is no children's language dictionary in Italian arranged according to age bracket, we chose words used in children and in pre-school reading material.     

Acrytonitrile block copolymers

Summary Acrylonitrile was polymerized by an insertion process on being added to solutions containing the adduct of the reaction of tetrakis(dimethylamino) titanium (T4) and azobisisobutyronitrile (AIBN). The obtained azo-linked polyacrylonitrile has appropriate initiating functionality for a subsequent vinyl polymerization.     

IGNITION DELAY CHARACTERISTICS OF SOME TURKISH VEGETABLE OIL-DIESEL FUEL BLENDS

Vegetable oils have chances to be used in Diesel engines as alternative fuels contributing to the solution of some agricultural, environmental and economical problems. Direct use of them has some technical problem yet but as blended fuels with diesel fuel or esters they have places on the application area. In this paper the effect of the compression ratio on ignition delay is investigated in an ASTM-CER engine working with four different types of vegetable oil of Turkish origin (sunflower, corn, soybean, and olive oil) blended with grade No.2-D diesel fuel at a ratio of 20/80 (v/v) and the results are compared with baseline diesel fuel. Longer ignition delay periods have generally been obtained for blend fuels ranking from olive oil to sunflower oil as compared to diesel fuel.     

Analysis and Implementation of Multiple–Input, Multiple–Output VBLAST Receiver From Area and Power Efficiency Perspective

This paper presents an analysis of the vertical Bell Laboratories layered space time (VBLAST) receiver used in a multiple-input multiple-output (MIMO) wireless system from the hardware implementation perspective and identifies those processing elements that consume more area and power due to complex signal processing. This paper models a scalable VBLAST receiver based on minimum mean square error (MMSE) nulling criteria assuming a block flat fading channel. After identifying the major area and power consuming blocks, this paper proposes two area and power efficient VLSI architectures for the block that computes pseudoinverse of the channel matrix. This paper discusses different tradeoff issues in both architectures and compares them with the architectures in the literature     

Sulfur capture for fluidized-bed combustion of high-sulfur content lignites

Sulfur release and capture behavior of lignites with highly combustible sulfur-contents were investigated by extending a previously-developed comprehensive model to incorporate sulfur retention. The predictive performance of the model was tested by comparing the model predictions with on-line concentration measurements of O₂, CO₂, CO and SO₂. Favorable comparisons are obtained between the predicted and measured concentrations of gaseous species along the combustor. Results show that freeboard sulfur-capture is enhanced significantly with recycling of elutriated sorbent particles as the sulfur release to the freeboard is significant for fuels rich in combustible sulfur.