Concatenation of space‐time block codes and turbo trellis coded modulation (ST‐TTCM) over Rician fading channels with imperfect phase

In this paper, the performance of space time‐turbo trellis coded modulation (ST‐TTCM) is evaluated over Rician and Rayleigh fading channels with imperfect phase. We modify Baum–Welch (BW) algorithm to estimate the fading and phase jitter parameters for multi‐antenna configurations. Thus, we assume that the channel parameters change slower than carrier frequency. We know that, at high data rate transmissions over wireless fading channels, space–time block codes (STBC) provide the maximal possible diversity advantage. Here, the combined effects of the amplitude and the phase of the received signal are considered, each one modelled by Rician and Tikhonov distributions, respectively. We investigate space time‐turbo trellis coded modulation (ST‐TTCM) for 8‐PSK for several Rician factor K and phase distortion factor η. Thus, our results reflect the degradations both due to the effects of the fading on the amplitude and phase noise of the received signal while the channel parameters are estimated by BW algorithm. Copyright © 2004 John Wiley & Sons, Ltd.     

Effect of Dynamic Compaction on the Retention of Tetragonal Zirconia and Mechanical Properties of Alumina/Zirconia Composites

Dynamic consolidation techniques were employed to investigate the retention of tetragonal zirconia and degree of consolidation in alumina/zirconia powder compacts. Heating the specimens prior to explosive shock compaction increased the tetragonal-phase retention significantly. Low shock pressures yielded no macrocracking, although final densities were low (60% to 70% of the theoretical density). Heat treatment following dynamic consolidation enhanced the retention of the tetragonal zirconia polymorph regardless of the shock pressure employed. Compact densities were increased to over 90% of theoretical at relatively low sintering temperatures (1300°C). Hardness, toughness, and Young's modulus of the compacts were comparable to those achieved in composites that were synthesized using more conventional techniques. Dynamic compaction offers an alternative method for the fabrication of zirconia-toughened alumina ceramics.     

Corrosion inhibition of benzyl triethanol ammonium chloride and its ethoxylate on steel in sulphuric acid solution

The inhibitive effect of benzyl triethanol ammonium chloride (BTAC) and ethoxylated benzyl triethanol ammonium chloride (EBTAC) on the corrosion of carbon steel in sulphuric acid solution is measured by the weight loss method. The adsorption of these compounds (surfactants) leads to the formation of a monolayer on the metal surface. The relationships between the concentrations of these inhibitors and their surface properties, thermodynamic properties, surface coverage (θ) and inhibiting efficiency have been investigated. The results indicate that EBTAC is superior to BTAC.     

1,3-cycloaddition of nitrile oxide to olefinic fatty acid esters: synthesis of isoxazolines

Fatty acid isoxazolines were prepared as 1,3-cyclo adducts by the reaction of dipolar nitrile oxides and dipolarophilic olefinic fatty esters. The structures of the isoxazolines were established with the help of elemental analysis, infrared, nuclear magnetic resonance and mass spectrometry spectral data.     

A regenerative centrifuge drive using a current-fed inverter withvector control

The authors describe the development of a centrifuge drive based on a current-fed inverter. The power circuit circuit is briefly described and a block diagram of the vector control is presented. Experience in tuning the speed regulator and modifying the torque pulsations in order to prevent coupling chatter is discussed. A specially shaped enclosure was designed to accommodate the end user's space requirement and also to provide space for the electronics that control the sequence of operation. A number of these drives have been in operation for more than two years, and operating experience concerning cycle time, power consumption, and reliability is presented     

Fatal Campylobacter jejuni infection in a patient splenectomised for thalassaemia

A 35 year old man with a fatal Campylobacter jejuni infection is described. He had HbE/beta zero thalassaemia and had undergone splenectomy nine months previously for hypersplenism; he also had chronic hepatitis C infection. He presented with high grade fever but no gastrointestinal symptoms and rapidly progressed to septicaemic shock and hepatic encephalopathy despite treatment with penicillin, gentamicin, and, later, chloramphenicol and ceftazidime. Only one case of Campylobacter jejuni septicaemia occurring post-splenectomy has been reported previously, also in an iron overloaded thalassaemia patient. Unusual Gram negative bacilli must be covered by the chosen antibiotic regimen when splenectomised thalassaemic patients present with high grade fever.     

A facile solid-state heating method for preparation of poly(3,4-ethelenedioxythiophene)/ZnO nanocomposite and photocatalytic activity

Poly(3,4-ethylenedioxythiophene)/zinc oxide (PEDOT/ZnO) nanocomposites were prepared by a simple solid-state heating method, in which the content of ZnO was varied from 10 to 20 wt%. The structure and morphology of the composites were characterized by Fourier transform infrared (FTIR) spectroscopy, ultraviolet-visible (UV-vis) absorption spectroscopy, X-ray diffraction (XRD), and transmission electron microscopy (TEM). The photocatalytic activities of the composites were investigated by the degradation of methylene blue (MB) dye in aqueous medium under UV light and natural sunlight irradiation. The FTIR, UV-vis, and XRD results showed that the composites were successfully synthesized, and there was a strong interaction between PEDOT and nano-ZnO. The TEM results suggested that the composites were a mixture of shale-like PEDOT and less aggregated nano-ZnO. The photocatalytic activity results indicated that the incorporation of ZnO nanoparticles in composites can enhance the photocatalytic efficiency of the composites under both UV light and natural sunlight irradiation, and the highest photocatalytic efficiency under UV light (98.7%) and natural sunlight (96.6%) after 5 h occurred in the PEDOT/15wt%ZnO nanocomposite.     

Treatment of sewage and industrial wastewater effluents by the cyanobacteria Nostoc muscorum and Anabaena subcylinderica

The potential of two cyanobacteria, Nostoc muscorum and Anabaena subcylindrica to treat sewage and industrial wastewater effluents was investigated. Two different sites were selected for this study which are located at the drains of sewage plant, a salt and soda production company at Kafr El-Zayat city. All samples were taken from the sewage and/or industrial effluents before treatment. Treatment of the sewage and industrial wastewater effluents by using cyanobacteria (N. muscorum, A. subcylindrica and mixed culture of both) revealed that the pH value of the biologically treated wastewater increased, the electrical conductivity was recovered in a range between (4.7–23.9%) and the total dissolved solids were reduced by (4.4–23.3%). The reduction of turbidity level was in a range between (40–96.4%). The removal efficiency of organic matter (COD, PV) was in a range between (20–57.1%) and (25.7–66.7%), respectively. Phosphorus reduction, nitrate treatment and ammonia elimination efficiencies by cyanobacterial system were (20.8–95%), (19.6–80%) and (20.9–96%), respectively. With respect to the treatment efficiency of wastewater by using single or mixed cultures of cyanobacteria, it was observed that the single cultures in most cases was better than the mixed cultures and this may be due to the competition between mixed cultures for nutrients. However, it could be concluded from the presented data that the treatment of wastewater by cyanobacteria is a fruitful method to produce an effluent of high quality to be used for irrigation.     

Non-linear analysis of membrane action effect in profiled steel sheeting dry board flooring system

This study highlights the effect of membrane action in improving load carrying capacity of Profiled Steel Sheeting Dry Board (PSSDB) floor system. PSSDB system is a lightweight composite structural system composed of profiled steel sheeting and dry board, attached together by self-drilling and self-tapping screws. Many literatures have reported that restricting conventional slabs, such as reinforced concrete slab, at the supports against translation and/or rotation while it is subjected to vertical loading develops the compressive membrane action in the slab. The development of this phenomenon is considered in the PSSDB system with concrete infill for continuous and practical spans, with and without topping concrete. Previous authors’ experimentally verified non-linear finite element model for the PSSDB floor without topping was extended to parametrically predict the effect of different boundary conditions on the performance of the system for practical applications. It was revealed that preventing the in-plane movement of the slab ends improves the flexural rigidities of the slab up to more than three times when considering central deflection of serviceability limit state. This was observed when the deflection limit load of the fixed both end supports model was compared to the pin-roller support model. Moreover, the topping concrete enhances the applicability of the system in longer span and the developed compressive membrane action dramatically boosts the load carrying capacity of the slab with restricted translation and/or rotation of the slab ends.