Performance Enhancement of Dynamic Spectrum Access via Channel Reservation for Cognitive Radio Networks

Wireless Personal Communications - In cognitive radio networks models, quality of service (QoS) of primary users (PUs) must be assured. Dynamic spectrum access is a paradigm by which a radio system...     

Millimeter-Wave Concurrent Beamforming: A Multi-Player Multi-Armed Bandit Approach

The communication in the Millimeter-wave (mmWave) band, i.e., 30~300 GHz, is characterized by short-range transmissions and the use of antenna beamforming (BF). Thus, multiple mmWave access points (APs) should be installed to fully cover a target environment with gigabits per second (Gbps) connectivity. However, inter-beam interference prevents maximizing the sum rates of the established concurrent links. In this paper, a reinforcement learning (RL) approach is proposed for enabling mmWave concurrent transmissions by finding out beam directions that maximize the long-term average sum rates of the concurrent links. Specifically, the problem is formulated as a multiplayer multiarmed bandit (MAB), where mmWave APs act as the players aiming to maximize their achievable rewards, i.e., data rates, and the arms to play are the available beam directions. In this setup, a selfish concurrent multiplayer MAB strategy is advocated. Four different MAB algorithms, namely, ϵ-greedy, upper confidence bound (UCB), Thompson sampling (TS), and exponential weight algorithm for exploration and exploitation (EXP3) are examined by employing them in each AP to selfishly enhance its beam selection based only on its previous observations. After a few rounds of interactions, mmWave APs learn how to select concurrent beams that enhance the overall system performance. The proposed MAB based mmWave concurrent BF shows comparable performance to the optimal solution.     

Beamforming with 2D-AOA estimation for pilot contamination reduction in massive MIMO

Telecommunication Systems - Connected vehicles network is designed to provide a secure and private method for drivers to use the most efficiently the roads in certain area. When dealing with the...     

Electrocoagulation/electroflotation of real printing wastewater using copper electrodes: A comparative study with aluminum electrodes

Most studies investigated electrocoagulation/electroflotation process (EC/EF) using either aluminum or iron electrodes. The main aim of this study is to investigate the performance of EC/EF to treat printing wastewater under various experimental conditions using copper electrodes. The effects of several variables, including different electrode materials (copper and aluminum), different current densities, electrolysis time, and spacing between electrodes on the removal efficiency of various parameters were investigated. The results showed that the maximum removal efficiencies for COD,TDS, and oil and grease were obtained when using a copper electrode. The maximum removal efficiencies were obtained at a gap distance of 4 cm.     

Design and synthesis of novel bichalcophene derivatives with double anchoring groups for dye-sensitized solar cell applications: sensitization and co-sensitization with N-719

Journal of Materials Science: Materials in Electronics - Novel dyes F1-3 based on bichalcophene-pyrimidine-2,4,6-trione derivatives with dual anchoring were developed, synthesized, and evaluated as...     

Serrated Flow and Enhanced Ductility in Coarse-Grained Al-Mg Alloys

Conventionally, superplasticity requires the presence of a fine-grained microstructure to enable grain-boundary sliding to take place during deformation. However, coarse-grained materials have also been shown to exhibit higher than normal amounts of ductility, provided they possess a high-enough strain rate sensitivity. In this work, coarse-grained Al-3 pct Mg, Al-5 pct Mg, and AA 5056 alloys were tested for enhanced ductility. The dependence of flow stress on temperature was found to display some unusual characteristics; these were interpreted as resulting from the occurrence of dynamic strain aging (DSA). In these materials, a local peak in elongation coincided with the presence of an unusual peak in rate sensitivity. This region of higher than normal rate sensitivity was coupled with the usual region of negative rate sensitivity found in DSA-prone materials, such as the Al-Mg alloys. A maximum ductility of 170 pct was recorded at 723 K (450 °C) and a strain rate of 5 × 10⁻² seconds⁻¹ was found in the vicinity of the rate sensitivity peak. This was found to increase to nearly 300 pct when the gage length was shortened. These peaks in elongation occurred below the maximum test temperatures.     

Proposed Energy Efficient Algorithm for Clustering and Routing in WSN

Wireless Personal Communications - Clustering in WSN recently become big challenge and attracts many researches. Clustering is a way of grouping sensor nodes into clusters with CH responsible to...     

Investigating the Electrical and Thermal Characteristics of Bismuth/(Polyvinyl alcohol/Acrylic Acid) Nanocomposites Membranes Prepared by Ionizing Radiation

In this work, thin nanocomposite membranes of polyvinyl alcohol (PVA)/acrylic acid (AAc)/bismuth were synthesized by means of ionizing radiation induced copolymerization of AAc with PVA in the presence of different Bi(NO₂)₃ concentrations. The prepared nanocomposite membranes were characterized by studying gelation percent, FTIR and water uptake. The nanocomposite formation was confirmed by examining the X-ray diffraction patterns and transmission electron microscope micrographs. The effect of the inclusion of Bi nanoparticles within the prepared membrane on their thermal stability was investigated by thermogravimetric analysis. The electrical resistivity of the prepared nanocomposite membranes were also studied. The results showed that the inclusion of Bi nano particles within the (PVA/AAc) membranes improve their electrical properties such improvement may recommend the prepared nanocomposite to be used in some electrochemical applications.     

Caffeic Acid Phenethyl Ester: A Review of Its Antioxidant Activity,Protective Effects against Ischemia-reperfusion Injury and Drug Adverse Reactions

Propolis, a honey bee product, has been used in folk medicine for centuries for the treatment of abscesses, canker sores and for wound healing. Caffeic acid phenethyl ester (CAPE) is one of the most extensively investigated active components of propolis which possess many biological activities, including antibacterial, antiviral, antioxidant, anti-inflammatory, and anti-cancer effects. CAPE is a polyphenolic compound characterized by potent antioxidant and cytoprotective activities and protective effects against ischemia–reperfusion (I/R)-induced injury in multiple tissues such as brain, retina, heart, skeletal muscles, testis, ovaries, intestine, colon, and liver. Furthermore, several studies indicated the protective effects of CAPE against chemotherapy-induced adverse drug reactions (ADRs) including several antibiotics (streptomycin, vancomycin, isoniazid, ethambutol) and chemotherapeutic agents (mitomycin, doxorubicin, cisplatin, methotrexate). Due to the broad spectrum of pharmacological activities of CAPE, this review makes a special focus on the recently published data about CAPE antioxidant activity as well as its protective effects against I/R-induced injury and many adverse drug reactions.