Blind decentralized projection receiver for asynchronous CDMA in multipath channels

An asynchronous direct sequence code division multiple access (DS-CDMA) system employing periodic spreading sequences is considered to be operating in a frequency selective channel. The cyclostationary spread signal is received at multiple sensors and/or is sampled multiple times per chip (oversampling), leading to a stationary vector-valued received signal. Hence, such a model represents a very particular multi-input multi-output (MIMO) system with plentiful side information in terms of distinct spreading waveforms for the input signals. Depending upon the finite impulse response (FIR) length of the propagation channel, and the processing gain, the channel of a certain user spans a certain number of symbol periods, thus inducing memory or intersymbol interference (ISI) in the received signal in addition to the multiple-access interference (MAI) contributed by concurrent users. The desired user’s multipath channel estimate is obtained by means of a new blind technique which exploits the spreading sequence of the user and the second-order statistics of the received signal. The blind minimum mean square error-zero forcing (MMSE-ZF) receiver or projection receiver is subsequently obtained. This receiver represents the proper generalization of the anchored MOE receiver [1] to the asynchronous case with delay spread. Classification of linear receivers obtained by various criteria is provided and the MMSE-ZF receiver is shown to be obtainable in a decentralized fashion by proper implementation of the unbiased minimum output energy (MOE) receiver, leading to the minimum variance distortionless response (MVDR) receiver for the signal of the desired user. This MVDR receiver is then adapted blindly by applying Capon’s principle. A channel impulse response is obtained as a by-product. Lower bounds on the receiver filter length are derived, giving a measure of the ISI and MAI tolerable by the receiver and ensuring its identifiability.     

Performance analysis of various hybrid renewable energy systems using battery,hydrogen, and pumped hydro‐based storage units

The aim of this research is to analyze the techno‐economic performance of hybrid renewable energy system (HRES) using batteries, pumped hydro‐based, and hydrogen‐based storage units at Sharurah, Saudi Arabia. The simulations and optimization process are carried out for nine HRES scenarios to determine the optimum sizes of components for each scenario. The optimal sizing of components for each HRES scenario is determined based on the net present cost (NPC) optimization criterion. All of the nine optimized HRES scenarios are then evaluated based on NPC, levelized cost of energy, payback period, CO₂ emissions, excess electricity, and renewable energy fraction. The simulation results show that the photovoltaic (PV)‐diesel‐battery scenario is economically the most viable system with the NPC of US$2.70 million and levelized cost of energy of US$0.178/kWh. Conversely, PV‐diesel‐fuel cell system is proved to be economically the least feasible system. Moreover, the wind‐diesel‐fuel cell is the most economical scenario in the hydrogen‐based storage category. PV‐wind‐diesel‐pumped hydro scenario has the highest renewable energy fraction of 89.8%. PV‐wind‐diesel‐pumped hydro scenario is the most environment‐friendly system, with an 89% reduction in CO₂ emissions compared with the base‐case diesel only scenario. Overall, the systems with battery and pumped hydro storage options have shown better techno‐economic performance compared with the systems with hydrogen‐based storage.     

Improvement of Electrical Characteristics of SiGe Source Based Tunnel FET Device

Silicon - Tunnel Field Effect Transistor (TFET) is one of the most promising alternative device for semiconductor technology and shows better performance as compared to the conventional MOS device...     

A Unified Approach for Physical and Geometric Modeling for Graphics and Animation

We present a unified approach for geometric and physical modeling using implicit functions, for application to graphics and animation. This method extends previously proposed techniques, and allows the standard finite element method to be directly combined with geometric modeling, resulting in quick calculation of an object's mass and stiffness matrices, and its vibration modes and frequencies. Because the approach is based on an implicitfunction representation, it allows very fast collision detection and characterization. Examples of complex physical and geometric modeling are presented.     

Angiosarcoma of the liver in children

The clinico-pathological features of four cases of pediatric hepatic angiosarcomas are described. One case was initially diagnosed in infancy and underwent resection of a left-sided benign hemangioendothelioma of the liver. Further resection of a lesion in the right liver was followed by malignant transformation. Primary hepatic resection of the tumor was not possible in three other cases, and all received courses of chemotherapy without significant tumor shrinkage. One child underwent liver transplantation but died 4 months later of immunosuppression complications. The remaining three children died of disseminated malignancy. Histological verification of malignancy was difficult in three cases in which there was discrepancy between the rapid growth of the liver tumor and the microscopic features of benign hemangioendothelioma.     

Designed synthesis of silver nanoparticles in responsive polymeric system for their thermally tailored catalytic activity towards hydrogenation reaction

Poly(N-isopropylacrylamide-acrylamide-methacrylic acid) [p(NIPa-AAm-Ma)] polymer microgels were prepared by free radical precipitation polymerization method. AgNPs were fabricated in the sieves of polymer network by chemical reduction using AgNO₃ salt as a precursor of silver ions. Various techniques like dynamic light scattering (DLS), transmission electron microscopy (TEM), Fourier transform infrared microscopy (FTIR), and UV-Visible spectroscopy were used for characterization of pure and composite microgels. The diameter of AgNPs fabricated in polymeric network was found to be in the range of 10-15 nm. Stimuli responsive behavior of hybrid microgels was same as that of pure microgels. Catalytic efficiency of the hybrid microgels was investigated by reducing 4-Nitroaniline (4-NA) into 4-Aminoaniline (4-AA) using NaBH₄ as reducing agent under different conditions of temperature of the medium, concentration of reducing agent, 4-Nitroaniline and hybrid microgels to explore the catalysis process. Kinetic and thermodynamic aspects of reduction of 4-Nitroaniline in the presence of catalyst were also discussed on the basis of values of Arrhenius and Eyring parameters like pre-exponential factor, activation energy, enthalpy of activation and entropy of activation. Catalytic activity of the hybrid microgels was found to be thermally tunable in the temperature range of 25-70 oC. The value of rate constant (k _app ) for reduction of 4-NA was minimum at 55 °C, which can be attributed to volume phase transition of the hybrid microgels.     

Numerical expressions of otolith shape and morphometric relationships for five fish species in tidal‐linked lagoons in the northern Arabian Sea

Otoliths from five fish species, including Acanthopagrus latus, Daysciaena albida, Ellochelon vaigiensis, Mugil cephalus and Mystus gulio, were used to develop numerical expressions involving otolith shape indices and morphometric parameters. A total of 342 fish specimens in lagoons (24°39′ 0N, 68°50′0E) were sampled from August 2014 to July 2015. A linear model related to fish sizes, otolith sizes and weights were applied, with estimated coefficients of determinations (r² = 0.99–0.53). Otolith shape indices, including form factor, roundness, aspect ratio, circularity, rectangularity and ellipticity for each fish species, also were analysed. The results of the present study are the first to describe relationships between otolith dimensions, fish morphometrics and shape indices of highly valued fish species and can be an important input for further trophic modelling to study food web dynamics.     

Field‐Free Programmable Spin Logics via Chirality‐Reversible Spin–Orbit Torque Switching

Spin–orbit torque (SOT)‐induced magnetization switching exhibits chirality (clockwise or counterclockwise), which offers the prospect of programmable spin‐logic devices integrating nonvolatile spintronic memory cells with logic functions. Chirality is usually fixed by an applied or effective magnetic field in reported studies. Herein, utilizing an in‐plane magnetic layer that is also switchable by SOT, the chirality of a perpendicular magnetic layer that is exchange‐coupled with the in‐plane layer can be reversed in a purely electrical way. In a single Hall bar device designed from this multilayer structure, three logic gates including AND, NAND, and NOT are reconfigured, which opens a gateway toward practical programmable spin‐logic devices.