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     

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.     

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     

Growth and characterization of Ni:DLC composite films using pulsed laser deposition technique

The structure and surface morphology of Ni-incorporated diamond like carbon (Ni:DLC) films have been investigated. These films were deposited on Si substrates using pulsed laser deposition (PLD) technique. A KrF Excimer laser (λ = 248 nm) was used for co-ablation from multi component Ni–graphite target. The concentration of Ni was varied by ablating the Ni part of the target with various numbers of laser pulses. The SEM and AFM analysis reveals that the surface is composed of segregates of Ni which increases with the increase in Ni content during the growth process. The structural investigations by XRD and Raman spectroscopy provided information about the orientation of the incorporated constituent and the ordering of the carbon species. Maximum height of the nano structures which were observed on the surface was ∼50 nm. The G-peak of the graphite was shifted towards higher wave number due to enhancement in SP² sites which have been increased due to the increase in the Ni concentration. A small change in the surface roughness ranging from 7.78 nm to 13.1 nm due to increased Ni concentration was also observed.     

Ranging Accuracy in Dynamic Spectrum Access Networks

Theoretical analysis of time-of-arrival (TOA)-based high-precision ranging algorithm for the dynamic spectrum access networks (DSANs) is performed. The asymptotic frequency-domain Cramer-Rao bound (CRB) of the ranging algorithm that takes the frequency-dependent feature (FDF) and phase of multipath components (MPCs) into account is derived through Whittle formula. The effects of FDF-MPCs and related parameters such as absolute bandwidth and operating center frequency on the ranging accuracy are investigated. The results show that the impacts of the FDF-MPCs on the ranging accuracy can be significant and it is recommended utilizing as large absolute bandwidth as possible at low operating center frequencies to obtain high-precision distance information of the users in the DSANs     

牛奶蛋白纤维(第Ⅰ部分)

牛奶蛋白纤维是一种新颖的工业生产纤维,中国已拥有2项发明专利.2004年它就已经通过了国际生态纺织品Oeko-Tex标准100认证.牛奶蛋白纤维是利用新型生物工程技术将牛奶去水脱脂,加工成适用于湿法纺丝工艺的蛋白浆后制得的纤维.它对皮肤友好,手感舒适,色彩鲜艳,具有很好的可染性.牛奶蛋白纤维可以纯纺或与羊绒、蚕丝、棉、毛、麻及其他纤维混纺.     

Power Doppler findings in nasopharingeal angiofibroma

Three fractions of polysaccharides that have high biological activity were extracted from Chinese bamboo leaves (Indocalamus Tesselatus) with 0.9% sodium chloride, 1% ammonium oxalate and 85% ethanol. Their component sugars were investigated by paper chromatography developed with n-butanol-pyridine-water (6:4:3 by vol), and by gas chromatography with crown ester stationary-phase-fused silica capillary column. Their monosaccharide compositions are different from each other with glucuronic acid, galactose, arabinose, mannose, glucose, and xylose (52, 18, 9, 7 and 6%, respectively) in one fraction, only glucuronic acid in another and glucuronic acid, fucose, arabinose and xylose (36, 31, 24 and 9%, respectively) in the third fraction. The protection effect of two polysaccharides against experimental hepatitis was studied in mice.