Symbol Detection Based on Back Tracking Search Algorithm in MIMO-NOMA Systems

One of the most important methods used to cope with multipath fading effects, which cause the symbol to be received incorrectly in wireless communication systems, is the use of multiple transceiver antenna structures. By combining the multi-input multi-output (MIMO) antenna structure with non-orthogonal multiple access (NOMA), which is a new multiplexing method, the fading effects of the channels are not only reduced but also high data rate transmission is ensured. However, when the maximum likelihood (ML) algorithm that has high performance on coherent detection, is used as a symbol detector in MIMO NOMA systems, the computational complexity of the system increases due to higher-order constellations and antenna sizes. As a result, the implementation of this algorithm will be impractical. In this study, the backtracking search algorithm (BSA) is proposed to reduce the computational complexity of the symbol detection and have a good bit error performance for MIMO-NOMA systems. To emphasize the efficiency of the proposed algorithm, simulations have been made for the system with various antenna sizes. As can be seen from the obtained results, a considerable reduction in complexity has occurred using BSA compared to the ML algorithm, also the bit error performance of the system is increased compared to other algorithms.     

Modeling and Optimization of SE and SI of Copper Flotation via Hybrid GA–ANN

In the present paper, a new attitude has been proposed for optimization of the separation efficiency (SE) and the Gaudin’s selectivity index (SI) in a flotation process by Hybrid artificial neural network (ANN) and genetic algorithm (GA). The chemical reagent’s dosage (collector, frother and fuel oil), pH, solid percentage, feed rate, Cu, Mo, and Fe grades in the flotation feed were selected as input variables and the SE-Cu and SI-Mo and SI-Fe were selected as output ones. Multilayer NN with back propagation (BP) algorithm was trained by the standard Bayesian regulation algorithm in which the validation data set did not required to be apart from its training. This algorithm with four-layer was used to relate output and input variables. Employment of Hybrid GA–ANN method resulted in significant improvement on GA fitnesses, as SE-Cu = 88, SI-Mo = 4.47 and SI of Fe = 12.85 were achieved. The input parameters corresponding to the fitnesses were as follows: pH = 12.25; the grade of Cu = 0.55%, Mo = 0.04% and Fe = 5.53%; the collector, frother and fuel–oil concentrations being 16.55, 15.54 and 2.71 (g/ton), respectively; the solid percentage was 25.84% and feed rate was 38,380 ton/day. The best fitness of GA was obtained after 10 generations by MSE value of 2.23.     

Deformation of Mesoporous Titania Nanostructures in Contact with D2O Vapor

For many applications, mesoporous titania nanostructures are exposed to water or need to be backfilled via infiltration with an aqueous solution, which can cause deformations of the nanostructure by capillary forces. In this work, the degree of deformation caused by water infiltration in two types of mesoporous, nanostructured titania films exposed to water vapor is compared. The different types of nanostructured titania films are prepared via a polymer template assisted sol–gel synthesis in conjunction with a polymer‐template removal at high‐temperatures under ambient conditions versus nitrogen atmosphere. Information about surface and inner morphology is extracted by scanning electron microscopy and grazing incidence small‐angle neutron scattering (GISANS) measurements, respectively. Furthermore, complementary information on thin film composition and porosity are probed via X‐ray reflectivity. The backfilling induced deformation of near surface structures and structures inside the mesoporous titania films is determined by GISANS before and after D₂O infiltration. The respective atmosphere used for template removal influences the details of the titania nanostructure and strongly impacts the degree of water induced deformation. Drying of the films shows reversibility of the deformation.     

Effect of medication on biomechanical properties of rabbit bones: heparin induced osteoporosis

BACKGROUND: We hypothesize that the integrity of the latissimus dorsi muscle graft used to wrap the heart may affect the clinical outcome of patients undergoing dynamic cardiomyoplasty. METHODS: By correlating the pathologic findings with their clinical course in five patients who died 1 month to 6 years after dynamic cardiomyoplasty operation, we sought to discern findings that might shed light on the pathophysiology of cardiomyoplasty. RESULTS: Of the two patients who had a limited clinical response, one had an atrophic, edematous latissimus dorsi muscle with fatty infiltration resulting from cardiac cachexia, and the other had insufficient length of latissimus dorsi muscle to cover a large heart. The remaining patients responded well clinically without signs of pump failure and died at various intervals, mostly of arrhythmias. Autopsy findings included the following: (1) one patient with ischemic cardiomyopathy as the underlying disease had development of rich vascularity in the interface between the muscle wrap and the epicardium; whereas in four others with idiopathic cardiomyopathy, such evidence of collateralization was far less evident. (2) There was a variation in the skeletal muscle transformation achieved, with the fraction type I fatigue-resistant fiber in the muscle wrap ranging from 60% to 100%, in spite of the identical transformation protocol used. Such variation is believed to be genetically based. (3) In one patient, the skeletal muscle was paced to contract at 30 to 50 times/minute (2:1 ratio) for more than 5 years. Nevertheless, the pathologic specimen of the muscle wrap showed only minimal interstitial fibrosis. (4) Relatively thin muscle wrap around the heart found at autopsy could be atrophy but most likely was related to muscle transformation, which is known to reduce muscle mass and increase capillary density. (5) All skeletal muscle grafts showed geometric conformation to the shape of the epicardium and grossly looked as if they were an additional layer of the ventricular wall. Such conformation may facilitate the modulation of the ventricular remodelling process in the failing heart, as has been described both in clinical and experimental studies. CONCLUSIONS: Our findings are consistent with and support a number of mechanisms proposed for cardiomyoplasty. Thus preservation of latissimus dorsi muscle graft integrity may be important in the success of dynamic cardiomyoplasty.     

Effect of Solution Treatment on Thermal Conductivity of Porous NiTi Shape Memory Alloy

In this study, a new solution treatment “solution treatment under loading” was applied to a porous Ni–50 at.%Ti shape memory alloy (SMA), which was fabricated by self-propagating high-temperature synthesis (SHS), to explore the microstructural improvement regarding single-phase NiTi. The effects of solution treatment under loading and without loading on the phase constituent and thermal conductivity were investigated and discussed. The phase constituent and thermal conductivity of the specimens considerably changed with solution treatment under loading, but they were not affected significantly with solution treatment without loading. Intermetallic phases such as B19′(NiTi), Ti₂Ni, and Ni₄Ti₃ disappeared, the density of the B2(NiTi) phase increased with solution treatment under loading, and thus the thermal conductivity was increased. It was also seen that the thermal conductivity of porous NiTi was less than that of solid NiTi.     

Residual concentration method for the problem of diffusion on the surface of a spherical cavity

The classical spherical diffusion equation is expressed in terms of a residual concentration. Thus, it becomes possible to eliminate the second derivative of the concentration with respect to the radial coordinate from the diffusion equation. This, in turn, leads to the advantage that diffusion on the surface of a spherical cavity can be studied by considering the cavity surface only. The case of a point source on the cavity surface is presented as an example for the application of the proposed Residual Concentration Method.     

Mechanical and Biochemical Characterisation of Wheat Gluten Films as a Function of pH and Co‐solvent

Dispersions of wheat gluten were prepared at different pHs (4, 6 and 11) in the presence or absence of ethanol. Films were obtained after casting suspensions followed by evaporation of the solvent. Films prepared at pH 11 were significantly stronger than the films prepared at pH 4 and 6 with tensile strengths of approximately 7 vs. 2 MPa. With increasing strength, the elongation at break was moderately reduced from approximately 300% to 190%. No significant variations of water vapour transfer rate properties were observed among the films. The solubility of gluten films in aqueous and 1.5% sodium dodecyl sulfate (SDS) solution decreased with increasing pH of films. Tricine sodium dodecyl sulfate‐polyacrylamide gel (SDS‐PAGE) patterns of wheat gluten and film showed the formation of high molecular weight fractions. The amount of free amino groups in the wheat gluten decreased during film formation. Amino acid analysis showed the presence of lysinoalanine (LAL). All these results indicate the formation of irreversible intermolecular cross‐linking upon film formation at pH 11.     

Enhancement of uranyl ion uptake by prestructuring of acrylamide–maleic acid hydrogels

Acrylamide–maleic acid (AAm–MA) hydrogels were prepared by gamma‐irradiation of their aqueous solutions. UO₂⁺² ion uptake on P(AAm–MA) hydrogels was investigated using two types of gel systems prepared by a simple irradiation method and a prestructured reaction. It has been observed that gels prestructured with UO₂⁺² ions adsorbed approximately 15–20% more UO₂⁺² ions than gels prepared in pure water (the usual method). It was also found that the uranyl ion adsorption capacity of hydrogels increased with an increasing amount of maleic acid in the gel system and an increasing concentration of uranyl ion in the solution. A possible interaction mechanism between the groups in the copolymeric gels and UO₂⁺² ion has been proposed based on the stoichiometry and the spectroscopic evidence. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 284–289, 2000