Empirical analysis of a 2 x 2 MIMO channel in outdoor-indoor scenarios for BFWA applications

The unquestionable advantages of multiple-input multiple-output (MIMO) systems are having a strong influence on the development of new wireless systems, both in wireless local-area networks (WLANs), and in those designed to offer broadband fixed wireless access (BFWA) services in wireless metropolitan-area networks (WMANs). The MIMO channel characterization in different environments and for different operating frequency bands is a crucial factor in the design of new systems and standards, and for adequate planning of existing systems. This article makes two main contributions. First, the experimental characterization of a 2 times 2 MIMO channel at a frequency of 2.4 GHz in a canonical outdoor-indoor scenario is presented. The channel characterization performed includes the analysis of the spatial correlation between the MIMO system subchannels and its impact on the channel capacity. Second, on the basis of the capacity results obtained, a proposal is made for the use of a 2 times 2 MIMO system in outdoor-indoor scenarios for BFWA applications in metropolitan environments. The proposal is based on the experimentally verified hypothesis that the path loss due to building penetration can be practically compensated for by the diversity gain of 2 times 2 systems     

Particle-Swarm Optimization in Antenna Design: Optimization of Log-Periodic Dipole Arrays

This paper presents a short tutorial and overview of optimization algorithms based on particle-swarm schemes, and their application to solving electromagnetic problems. As a practical example, a particle-swarm optimization (PSO) tool has been applied in conjunction with the Numerical Electromagnetics Code (NEC) to get the design curves of optimized log-periodic dipole arrays (LPDAs). The graphs show the performance of several radiation parameters (directive gain, front-to-back ratio, bandwidth, SWR, and half-power beamwidth in the E and H planes) as a function of typical design parameters of log-periodic dipole arrays (geometrical parameters and characteristics of the feed). Examples of optimized antennas are given, and their performance is compared to that of standard log-periodic dipole arrays.     

A framework for reconfigurable computing: task scheduling and context management-a summary

Reconfigurable computing is consolidating itself as a real alternative to ASICs (Application Specific Integrated Circuits) and general-purpose processors. The main advantage of reconfigurable computing derives from its unique combination of broad applicability, provided by the reconfiguration capability, and achievable performance, through the potential parallelism exploitation. The key aspects of the scheduling problem in a reconfigurable architecture are discussed, focusing on a task scheduling methodology for DSP and multimedia applications, as well as the context management and scheduling optimizations.     

Algorithm to decode 'identifiable parent property' codes

In a fingerprinting scheme, marks are embedded in a digital object to protect intellectual property. Dishonest users can collude, change some of the marks and create a new copy. In this case codes with the 'identifiable parent property' or IPP codes [4], provide means of traceability. Here, both a new decoding algorithm for IPP codes and an improvement of earlier algorithms are presented.     

High-temperature study of zirconia gels: Evolution of surface area and porosity on calcination in a vacuum

Zirconium dioxide, prepared by dehydration of a zirconia gel, was calcined in a vacuum at temperatures ranging from 573 to 1173K, in order to investigate the evolution of specific surface area and porosity as a function of the calcination temperature. The results are compared with those previously obtained for samples heated in air.Samples fired up to 773 K were found to be basically microporous, with surface areas ranging from 142 to 93 m²g^?1. Calcination at 973 K led to total elimination of microporosity and reduction of surface area by about 50%. In the temperature range 773–1173 K, the most frequent pore radius was found to increase from 1.5 to 10.5 nm as the temperature was raised.     

General solution for single-layer electromagnetic-wave absorber

A general solution for perfect absorption under normal incidence in a single-layer homogeneous absorber backed by a perfect conductor is derived considering both electric and magnetic losses. Design curves and equations are given for the lowest-order or minimum-thickness solutions, and its possible use in the design and fabrication of practical absorbing materials is also illustrated.     

Anthropometry of south Indian industrial workmen.

This paper presents the results of an anthropometric survey conducted on South Indian male workers in the electronic industry. The data were collected as part of a project to modify work stations that utilized equipment from other countries. A set of 27 body dimensions were taken from a sample of 128 workmen (aged 18-35 years). The anthropometric measurements are compared with those of Indian men from Central, Western, and Northern parts of India and with those of the American, German, and Japanese men. The results indicate that in general the South Indian man is smaller than Central, Western, and Northern Indian men, as well as smaller than men in America, Germany, Japan, and Africa. This difference needs to be allowed for when considering buying and subsequently using imported equipment for the electronics industry in South India.     

C-terminal extension of the H2-activating subunit, HoxH, directs maturation of the NAD-reducing hydrogenase in Alcaligenes eutrophus

Idiopathic myelofibrosis, or agnogenic myeloid metaplasia, is a chronic myeloproliferative disorder characterized by clonal expansion and marrow fibrosis. Although marrow fibrosis appears to be a reactive process, it substantially contributes to impaired haemopoiesis. During the last few years the implication of megakaryocyte-derived growth factors in its pathogenesis has been documented. We previously reported increased expression of TGF-beta in patients with idiopathic myelofibrosis. In the present study we show that circulating megakaryocytic cells from such patients expressed high levels of basic fibroblast growth factor (bFGF). An increased expression of bFGF was also detected in patients' platelets. Under culture conditions, bFGF present in megakaryocytic cells was not exported into the medium. consistent with the fact that bFGF is devoid of a secretion peptide signal. Interestingly, this lack of bFGF secretion was observed in all patients but one, who was in an accelerated phase of the disease and presented an important percentage of circulating megakaryoblasts.     

Kinetics of release of serotonin from isolated secretory granules. II. Ion exchange determines the diffusivity of serotonin

We measured the efflux of 5-hydroxytryptamine (5-HT, serotonin) from an intact secretory granule extracted from the mast cell of the beige mouse. The efflux was measured with amperometry after rupture of the granule membrane was triggered by electroporation. We determined the diffusivity of 5-HT within the secretory granule to be 2.0 x 10(-8) cm2 s(-1) when the granule is in contact with a physiological saline and found that this diffusivity depends on the valence of the cation in the external electrolyte. There is a fivefold increase in the diffusion coefficient of 5-HT determined in CsCl (150 mM, pH 7.2) at 3.7 x 10(-8) cm2 s(-1) compared to that determined in histamine dihydrochloride (Hi, 100 mM at pH 4.5) at 0.7 x 10(-8) cm2 s(-1). We found that the rate of expansion of the granule matrix observed in physiological medium correlates with the efflux of 5-HT, and that the rate of swelling of the matrix and the efflux depend on the microviscosity within the granule matrix and not the bulk viscosity of the external solution. The low diffusivity of 5-HT (approximately 500-fold less than in the bulk), the observation that the valence of the counterion affects this diffusivity, and the relationship between the volume changes of the matrix and the efflux suggest that 5-HT is released from the granule by ion exchange. We discuss the implications of this result for exocytotic release in mast cells and propose that an ion exchange mechanism could control the rate of release in other secretory systems.     

Effects of fish meal and sodium bentonite on daily gain, wool growth, carcass characteristics, and ruminal and blood characteristics of lambs fed concentrate diets

We evaluated the effects of replacing some soybean meal (SBM) protein with fish meal (FM) protein in diets adequate and slightly deficient in CP, with or without .75% sodium bentonite (NaB) on performance and ruminal and blood metabolites of individually fed Suffolk lambs. Diets were based on corn, SBM, and cottonseed hulls. In Exp. 1, five lambs were assigned to each of the three dietary treatments (11% CP with 3% FM, 13% CP with 0 or 3% FM). Lambs fed diets that contained 11% CP with 3% FM or 13% CP with 0% FM had similar DMI and ADG. Gain and feed efficiency were slightly improved (P = .18) by the 13% CP diet with 3% FM. In Exp. 2, 32 lambs were assigned to four dietary treatments (13.5% CP of DM) in a 2 x 2 factorial arrangement (0 or 3% FM, and 0 or .75% NaB on an as-fed basis). The DMI and ADG were increased (P < .05) by FM and NaB supplementation. Interactions (P < .05) revealed that NaB increased DMI, ADG, gain per feed (g/kg of DMI), and plasma urea N concentration in the absence of FM but not in the presence of FM in the diet. Neither FM nor NaB influenced (P = .25) wool growth. Total ruminal VFA were increased (P < .06) by FM and NaB. Differences in mineral content of phalanx bone, liver, and kidney were small and may be related to the mineral content of diets and the effect of NaB on mineral solubilities. Similar DMI and ADG of lambs fed FM and NaB separately and in combination suggest that their beneficial effect is not additive.