Multistage interference cancellation with diversity reception forasynchronous QPSK DS/CDMA systems over multipath fading channels

This paper introduces a multistage interference cancellation (MIC) technique with diversity reception for quadrature phase shift keying (QPSK) asynchronous direct-sequence code division multiple access (DS/CDMA) systems over frequency-selective multipath Rayleigh fading channels. Unlike the previous MIC, which tries to remove the lump sum of the multiple-access interference (MAI) and self-interference (SI), this introduced MIC attempts to cancel only the MAI and part of the SI due to the intersymbol interference, while treating the remaining SI created by the current symbol as useful information for symbol decision. In this technique, the RAKE combining is used to collect signal replicas over multiple fading paths. Upper and lower bounds on the bit error probability are derived using a Gaussian approximation and the characteristic function method. Furthermore, effects of channel estimation error on the performance are studied. Analytical and simulation results show that the introduced MIC can provide a performance extremely close to that in an ideal single-user environment and outperforms the previous MIC even in the presence of channel estimation error     

Effect of Hydrothermic Ageing on Dielectric and Mechanical Properties of Rigid Poly(vinyl chloride)

An accelerated hydrothermic ageing (according to N.F.T. 54043 method) was performed on samples of rigid poly(vinyl chloride). The test consisted of sample immersion in boiling water at 100°C for different exposure periods up to 480 h. The samples were removed from the boiling water every two hours for mechanical and dielectric characterization and color test. The dielectric measurements carried out on aged samples, up to 40 h, showed that the permittivity remained almost constant and its value was found to be 2.3 in the range –100 to +62.8°C. However, as the temperature approaches the glass transition (T_g = 88.3°C), the permittivity was observed to increase rapidly. It was also found that the permittivity of aged samples was lower than that of the non‐aged samples. The dielectric loss factor (tan δ) measurements with respect to temperature have confirmed the presence of two relaxations: β at low temperature (around –35°C) and α near the T_g. The combined action of water and temperature reduced the intensity of the corresponding relaxation peaks. The sample color index was evaluated up to 480 h using the SYNMERO scale in order to estimate the degradation extent. Unexpectedly, elongation at break under uniaxial traction remained unaffected by the hydrothermic ageing, meaning that two competing processes were involved simultaneously (sample degradation via chain scission and sample plastification via water absorption).     

Total Synthesis of Symbioramide: a Flexible Approach for the Efficient Preparation of Structural Isomers

A concise, enantioselective total synthesis of symbioramide, starting from simple achiral compounds and racemic α‐amino‐β‐keto ester derivatives is reported. This highly flexible strategy allowed the efficient preparation of seven structural isomers of the natural product as well. The synthesis relies on a convergent route that involves the efficient stereoselective reduction of a α‐keto‐β‐yne ester, and the dynamic kinetic resolution of an α‐amino‐β‐keto ester through ruthenium‐mediated asymmetric hydrogenation.     

Economic analysis of the energy-efficient household appliances and the rebound effect

Many strategies, such as improving energy efficiency, were identified as solutions to reduce energy consumption and carbon emissions. Nonetheless, the presence of a rebound effect could lead to a decrease in potential energy savings and carbon reductions resulting from technological advances in energy consumption. This study focuses on direct and indirect rebound effects on households’ behavior. We examine the situation where consumers demand two types of energy services and explore how their choices are affected by changes in the efficiency of providing these services—and, importantly, the consequent implications for energy use. We employ a (narrowly construed) general equilibrium methodology in an attempt to provide a complete picture of the interactions in play in a theoretically confined setting. We limit the general equilibrium problem to two categories of energy appliances but include consideration of the production side of the equation and consequent budget implications, thus “closing” the system in a general equilibrium sense. We find that rebound magnitudes (both indirect and direct) are large.     

Three-Dimensional Network Polymeric Structure of (2-Amino-5 Ammoniopyridinium)[CuCl4]: Crystal Supramolecularity and Magnetic Properties

A single crystal structure determination of the complex (C₅H₉N₃)CuCl₄ [henceforth I] has been carried out. It crystallizes in the orthorhombic space group Cmca, with the cell parameters a=6.7053(5) Å, b=22.4171(19) Å, c=13.4173(9) Å, V=2016.8(3) Å³, and Z=8. In the complex, the anion is comprised of infinite zigzag chains of monochloro-bridged $\mathrm{CuCl}_{4}^{2-}$ units ?–CuCl₃–μ–Cl–CuCl₃–μ–Cl–CuCl₃–? surrounded by the pyridinium-ammonium cations. The Cu ions are five-coordinate to chloride ions in a distorted square-pyramidal geometry with the zigzag chains formed by corner-sharing polyhedra. The Cu ion is located 0.151 Å above the basal plane. In the crystal, there are four intermolecular hydrogen bonding interactions, linking the CuCl chains to the cations to form a 2D-network. The resulting 2D-networks are further linked by aryl?aryl (π?π) interactions within the cationic chains leading to a 3D-network. Variable temperature magnetic susceptibility data were fit to a one-dimensional S=1/2 antiferromagnetic chain model yielding C=0.44(1) emu-K/mol-Oe and J=?37(1) K.     

Evaluating the impact of mass housings' in-between spaces' spatial configuration on users' social interaction

This research examines the impact of in-between space configuration on users' social practices. The effects of different degrees of permeability of these spaces on the social interactions of the inhabitants are also analyzed. This research is based on a comparative approach using space syntax analysis and snapshot observations on four mass housing neighborhoods in Setif, Algeria. The neighborhoods are selected according to their degree of permeability, location in the city, realization period, and syntax measures from integrated to segregated. The activity patterns of two-week days for each study case are observed and recorded. Correlation results of observed social activities and syntactic measures demonstrate that spatial configuration affects people's use of in-between spaces. Moreover, connectivity and clustering coefficients are revealed to be important indicators of social activities. Previous urban studies argued that integrated spaces are mostly used by people. However, social interaction in the studied cases increases in the least connected areas, adjoining spaces to the buildings, and most closed spaces. This research finds that social activities are dependent on the degree of permeability, which when low, gives rise to increased social interaction and activities.     

Electropolymerization of phenol on a vitreous carbon electrode in acidic aqueous solution at different temperatures

Electrochemical oxidation of phenol in acidic aqueous solution was studied on a vitreous carbon electrode at different temperatures in the range of 25–85 °C by cyclic voltammetry and chronoamperometry. The kinetic aspect of the phenol oxidation was investigated as a function of its concentration and temperature. The electrode deactivation by formation of an adherent, compact, and insulating polymeric film was examined by monitoring the decrease in the peak current of phenol oxidation during the course of successive potential scans. Repeated potential scans in the region of water stability did not reactivate the electrode whatever the temperature used. Chronoamperometric curves recorded at different potentials in the region of water decomposition shown that the electrochemical activity of the electrode was partially restored even when performed at low temperature (25 °C).     

Enhancing VANETs Broadcasting Performance with Mobility Prediction for Smart Road

Wireless Personal Communications - In the last decade, daily lifestyles have been invaded by mobile networks which added a huge exchange of information. This exchange among vehicular nodes as a...     

Toward the thermohydrodynamic behavior of a nanofluid containing C-MWCNTs flowing through a 3D annulus channel under constant imposed heat flux

The heat transport and friction factor in a three-dimensional horizontal concentric annular duct filled with nanofluids comprising clove-treated multiwalled carbon nanotubes are investigated numerically in this paper. The cylinder's outer surface is thermally insulated, while uniform heat flux is imposed on the cylinder's inner surface. The problem is formulated in dimensionless cylindrical coordinates. The numerical solutions were obtained based on the finite volume technique with second-order precision, and cover a range of the Reynolds number 1000 ≤ Re ≤ 2000 and nanoparticle weight fractions 0.075, 0.125, and 0.175 wt%. To describe the results for both heat exchange and fluid flow performance, the temperature profile, Nusselt number, heat transfer coefficient, and friction factor are represented. The findings state that heat transport increases as Reynolds is increased and nanoparticles are introduced. The friction factor was also observed to improve as the concentration of nanoparticles increased. In addition, two new Nusselt number and friction factor correlations were established.     

Superplastic deformation behavior of 7075 aluminum alloy

A study has been made to investigate the effect of a prior amount of warm rolling on the superplastic forming behavior of a standard grade 7075 aluminum alloy. The thermomechanical treatment process presented for grain refinement includes furnace cooling from the solution treatment temperature to the overaging temperature, warm rolling from 65–85% deformation, recrystallization, and artificial aging treatment. Increasing the amount of warm rolling beyond 80% deformation does not produce material with higher elongation to failure when the thermomechanical treatment process presented is used. The largest value of elongation to failure was 700%, which was obtained for a specimen having a grain size of 8 μm at a strain rate of 6×10⁻³S⁻¹. The fracture surface exhibits a granular appearance indicative of an intergranular fracture mode. Dislocation activities within grains were observed, indicating the occurrence of dislocation slip during grain boundary sliding.