Policy for enhancement of traffic in TDMA hybrid switchedintegrated voice/data cellular mobile communications systems

Major types of data for multimedia with mobile communications are voice, WWW, and FTP. Different regimes for quality of service (QoS) exist for each with reference to delay sensitivity. Sharing available radio resource has been inherently based on the characteristics of data types and their associated QoS. In this paper, we present a new policy for integrated services of voice and data that is pertinent to a TDMA system using a hybrid-switching mode. Our method provides significant improvements in traffic capacity for data with virtual transparency to voice users     

On improving training time of neural networks in mixed signal circuit fault diagnosis applications

Testing issues are becoming more and more important with the quick development of both digital and analog circuit industry. Analog-to-digital converters (ADCs) are becoming more and more widespread owing to their fundamental capacity of interfacing analog physical world to digital processing systems. In this paper, we study the use of neural networks in fault diagnosis of ADCs and compare the results with other ADC testing approaches such as histogram, FFT and sinewave curve fit test techniques. In this paper, we introduced the idea of separation of neural network’s output matrix to improve the training phase time, called ‘index-separation’ approach. Finally, we concluded that training time in this method is about 0.25 times as much as that in the normal training method. We also concluded that this approach does not affect network’s decision strength. Besides, we concluded that if the complexity of the circuit increases, this method will still be effective. Therefore, this method is a robust way for fault diagnosis of mixed signal circuits.     

Harnessing buildings’ operational diversity in a computational framework for high-resolution urban energy modeling

To achieve computational efficiency, efforts toward developing urban-scale energy modeling applications frequently rely on various domain simplifications. For instance, heat transfer phenomena are captured using reduced order models. As a consequence, specific aspects pertaining to the temporal dynamics of energy load patterns and their dependency on transient phenomena (e.g., weather conditions, inhabitants’ presence and actions) cannot be realistically represented. To address this circumstance, we have conceived, implemented, and documented a two-step urban energy modeling approach that combines cluster analysis and sampling techniques, full dynamic numeric simulation capability, and stochastic methods. The paper describes the suggested urban energy modeling approach and the embedded cluster analysis supported sampling methodology. More particularly we focus on the aspects of this approach that explicitly involve the representation of inhabitants in urban-scale energy modeling. In this regard, the potential to recover lost dynamic diversity (e.g., in computation of temporal load patterns) due to the deployed reductive sampling is explored. Parametric runs based on stochastic variations of underlying building use profiles facilitate the generation of highly realistic load patterns despite the small number of buildings selected to represent the simulation domain. We illustrate the utility of the proposed urban energy modeling approach to address queries concerning the energy efficiency potential of behaviorally effective instruments. The feasibility of the envisioned scenarios concerning inhabitants and their behavior (high-resolution temporal load prediction, assessment of behavioral variation) is presented in detail via specific instances of district-level energy modeling for the city of Vienna, Austria.     

Comparison between reconstituted and fresh skim milk chemical and electrochemical acidifications

The aim of this study was to compare the electrochemical and chemical acidification of reconstituted and fresh skim milk in terms of electrodialytic parameters, precipitation kinetics, chemical composition and physicochemical and functional properties of isolates produced by bipolar membrane electro acidification (BMEA). The electrodialytic parameters were not influenced by the type of milk when both milks were compared at a similar protein and salt content. The difference in precipitation kinetics observed between the two milks, whatever the acidification procedure, can be explained mainly by a difference in salt content. Isolates produced by BMEA showed similar physicochemical and functional properties (except for foaming capacity) to isolates produced chemically. The main factor affecting the composition and the physicochemical and functional properties was the pre‐treatment of milk prior to acidification: it had a higher impact on the functional properties than the acidification treatment itself. Copyright © 2002 Crown in the right of Canada. Published for SCI by John Wiley & Sons, Ltd     

Effects of interlayer density and surfactant on coupled thermal stress and moisture absorption in modified montmorillonite/polypropylene nanocomposite

Modified montmorillonite/polypropylene nanocomposites (NCs) are increasingly used in industrial applications such as subsea pipelines because hexadecyltrimethyl ammonium montmorillonite (HDTMA⁺-Mt) enhances thermomechanical and barrier properties of the amorphous polymer. Two coupled physics of moisture adsorption and thermal loading are investigated. Molecular dynamics simulates HDTMA⁺-Mt polymer NC using three force fields including polymer consistent force field and condensed-phase optimized molecular potentials, and embedded-atom method. Mechanical properties and self-diffusion coefficient are investigated at temperature levels of 100 and 298 K, and water content of 0.021 and 0.133 g/g. These properties are evaluated at 1.0 atm pressure for four different volume fractions (vol%) of the HDTMA⁺-Mt. The modeling procedure is verified by obtaining the glass transition temperature (T_g) of the NC by scanning the temperature from 200 K (glassy state) up to 325 K (rubbery state). It is observed that the T_g is very close to the experimental value available in the literature. The result of the modeling shows that the increase of clay content of the NC decreases the self-diffusion coefficient of the material. It is seen that the clay nanoparticle can significantly hinder the degradation of mechanical properties of the NC even when both temperature and water content increase.     

Interpenetrating polymer networks (IPN) based on gelatin/poly(ethylene glycol) dimethacrylate/clay nanocomposites: Structure–properties relationship

The effects of cross-linking sequence (simultaneous or sequential) and incorporation of exfoliated sodium-montmorillonite (Na⁺-MMT) nanoclay on the structure and properties of interpenetrating polymer networks (IPNs) based on gelatin/poly(ethylene glycol)dimethacrylate were studied by means of different complementary techniques. Gelatin and PEGdmA phases were cross-linked via chemical and in-situ UV curing, respectively. 2,2-dimethoxy-2-phenylacetophenone (DMPA) (1.5% w/w) was used as photo-initiator to cross-link PEGdmA. The results showed that the incorporation of small amount of Na⁺-MMT nanoplatelets accelerates the kinetics of chemical cross-linking of gelatin by glutaraldehyde (1.0% w/w). This led to a new hypothesis concerning the tuning structural evolution of the IPNs by the Na⁺-MMT content. In the case of simultaneous IPNs, in which both phases cross-linked at the same time, the accelerated cross-linking of gelatin in the presence of exfoliated sodium-montmorillonite led to increased structural homogeneity, improved mechanical and thermal properties. Incorporation of nanoclay did not show any significant effect on the structure and properties of the IPNs synthesized via sequential method in which gelatin and PEGdma phases were cross-linked separately. For the semi-IPNs, however, Na⁺-MMT induced macroscopic phase separation and resulted in lower mechanical properties. These results might shed light on the mechanisms underlying structure–property relationship in biohybrid IPNs based on gelatin as promising candidates for tissue engineering and drug delivery applications.     

Bidentate salen Cu(II) complex functionalized on mesoporous MCM-41 as novel nano catalyst for the oxidative coupling of thiols into disulfides using urea hydrogen peroxide (UHP)

Functionalized Copper(II) complex into nano dimensional mesoreactor was successfully prepared. The Copper(II) complex with N–O donor Schiff base ligand was readily trapped into mesoporous silica MCM-41 through the post grafting method. N–O Chelating Schiff-base-MCM-41 has been derived from 5-bromo-salicylaldehyde and 3-aminopropyltriethoxysilane which was functionalized on MCM-41 via silicon alkoxide route. This compound was characterized by FT-IR, TGA, small angle X-ray diffraction patterns, ICP/MS analysis and N₂ sorption–desorption analysis. The catalytic property of Cu–salen–MCM-41 was considered for the preparation of disulfides using urea hydrogen peroxide as oxidant. The reaction progress is simple and proceeds under mild and heterogeneous conditions in acetonitrile at the ambient of temperature. The corresponding disulfides have been achieved with high purity and good to excellent yields; also, no over oxidation to sulfoxide or sulfone was observed in all cases. The catalyst can be recovered and reused several times without significant loss of stability and activity.     

The application of building performance simulation in the writing of architectural history: Analysing climatic design in 1960s Israel

This article presents a methodology for the integration of building performance simulation (BPS) into the writing of architectural history. While BPS tools have been developed mainly for design purposes, their current maturity enables to reliably apply them in simulating the performance of past buildings, even when these buildings have been significantly modified or demolished. The possibility to virtually reconstruct the performance of past buildings can help us to overcome the existing knowledge gap in the understanding of the role played by building performance and building performance research through the history of architecture and can therefore promote the intelligent and successful application of environmental features in contemporary architecture. The potential of the proposed methodology is presented here using a historical case study from 1960s Israel (a university building in Tel Aviv), in which climatic considerations were anexplicit part of the entire design process. The original thermal performance of the building was analysed by employing the EnergyPlus simulation engine, and the simulation results were used for evaluating the climatic impact of certain design decisions, comparing them with the proclaimed design goals and the original intentions of the architects.     

Optimizing parameters affecting synthetize of CuBTC using response surface methodology and development of AC@CuBTC composite for enhanced hydrogen uptake

CuBTC, a widely studied metal-organic framework, is a promising candidate for industrial applications owing to its easy synthesis procedure and excellent textural properties. In this research CuBTC was synthesized by solvothermal method with the purpose of hydrogen uptake. Response surface methodology (RSM) was employed in order to determine the optimum synthesis condition with the highest hydrogen capacity. Amount of ligand, volume of solvent, synthesis temperature, and synthesis time were chosen as independent variables, while the amount of hydrogen uptake was selected as the response. Subsequently, activated carbon (AC) was incorporated within the optimized CuBTC structure as a “void space filling agent” and adsorption behavior of AC@MOF composite was evaluated from the view point of different AC contents. It was observed that the hydrogen uptake of AC@CuBTC composite was increased compared to bare CuBTC samples. This finding could be attributed to effective utilization of micropore volume of CuBTC structure by AC incorporation.     

Local thermal nonequilibrium conjugate natural convection heat transfer of nanofluids in a cavity partially filled with porous media using Buongiorno’s model

The natural convection heat transfer in a cavity filled with three layers of solid, porous medium, and free fluid is addressed. The porous medium and free fluid layers are filled with a nanofluid. The porous layer is modeled using the local thermal nonequilibrium (LTNE) model, considering the temperature difference between the solid porous matrix and the nanofluid phases. The nanofluid is modeled using the Buongiorno’s model incorporating the thermophoresis and Brownian motion effects. The governing equations are transformed into a set of nondimensional partial differential equations, and then solved using finite element method in a nonuniform grid. The effects of various nondimensional parameters are discussed. The results showed that the Brownian motion and thermophoresis effects result in significant concentration gradients of nanoparticles in the porous and free fluid layers. The increase in Rayleigh (Ra), Darcy (Da), the thermal conductivity ratios for the solid wall and solid porous matrix, i.e., K_r and R_k, enhanced the average Nusselt number. The increase in the convection interaction heat transfer parameter between the solid porous matrix and the nanofluid in the pores (H) increases the average Nusselt number in the solid porous matrix but decreases the average Nusselt number in the nanofluid phase of the porous layer.