Robust Beamforming for Secrecy Rate in Cooperative Cognitive Radio Multicast Communications

In this paper, we propose a cooperative approach to improve the security of both primary and secondary systems in cognitive radio multicast communications. During their access to the frequency spectrum licensed to the primary users, the secondary unlicensed users assist the primary system in fortifying security by sending a jamming noise to the eavesdroppers, while simultaneously protect themselves from eavesdropping. The main objective of this work is to maximize the secrecy rate of the secondary system, while adhering to all individual primary users' secrecy rate constraints. In the case of passive eavesdroppers and imperfect channel state information knowledge at the transceivers, the utility function of interest is nonconcave and involved constraints are nonconvex, and thus, the optimal solutions are troublesome. To address this problem, we propose an iterative algorithm to arrive at a local optimum of the considered problem. The proposed iterative algorithm is guaranteed to achieve a Karush-Kuhn-Tucker solution.Comment: 6 pages, 4 figures, IEEE ICC 201

Development of a Real-Time, Simple and High-Accuracy Fall Detection System for Elderly Using 3-DOF Accelerometers

© 2018, King Fahd University of Petroleum & Minerals. Falls represent a major problem for the elderly people aged 60 or above. There are many monitoring systems which are currently available to detect the fall. However, there is a great need to propose a system which is of optimal effectiveness. In this paper, we propose to develop a low-cost fall detection system to precisely detect an event when an elderly person accidentally falls. The fall detection algorithm compares the acceleration with lower fall threshold and upper fall threshold values to accurately detect a fall event. The post-fall recognition module is the combination of posture recognition and vertical velocity estimation that has been added to our proposed method to enhance the performance and accuracy. In case of a fall, our device will transmit the location information to the contacts instantly via SMS and voice call. A smartphone application will ensure that the notifications are delivered to the elderly person’s relatives so that medical attention can be provided with minimal delay. The system was tested by volunteers and achieved 100% sensitivity and accuracy. This was confirmed by testing with public datasets and it also achieved the same percentage in sensitivity and accuracy as in our recorded datasets

Assessment of Antioxidant Activities, Total Phenolics, and Flavonoids of Different Extracts of Strobilanthes Schomburgkii Leaves

The main purpose of this work was to assess the antioxidant activities of the n-hexane, ethyl acetate and methanol extracts of Strobilanthes schomburgkii leaves collected in Laocai province, Vietnam. Total phenolic and flavonoid contents were determined. The DPPH, H2O2 radical scavenging activity, and total antioxidant activity via phosphomolybdenum method were investigated. The results showed that the methanol extract concluded a high concentration of phenolics and flavonoids which were 65.42 mg/g and 52.05 mg/g, respectively. There was a significant correlation between total phenolic and flavonoid concentrations and EC50 values of different antioxidant assays. The antioxidant properties of the different extracts from Strobilanthes schomburgkii leaves were reported for the first time

New method for measuring azimuthal distributions in nucleus-nucleus collisions

The methods currently used to measure azimuthal distributions of particles in heavy ion collisions assume that all azimuthal correlations between particles result from their correlation with the reaction plane. However, other correlations exist, and it is safe to neglect them only if azimuthal anisotropies are much larger than 1/sqrt(N), with N the total number of particles emitted in the collision. This condition is not satisfied at ultrarelativistic energies. We propose a new method, based on a cumulant expansion of multiparticle azimuthal correlations, which allows to measure much smaller values of azimuthal anisotropies, down to 1/N. It is simple to implement and can be used to measure both integrated and differential flow. Furthermore, this method automatically eliminates the major systematic errors, which are due to azimuthal asymmetries in the detector acceptance.Comment: final version (misprints corrected), to be published in Phys.Rev.

Конструкция и характеристики неохлаждаемых болометрических инфракрасных решеток на основе аморфного кремния

Uncooled bolometric type thermal detectors, combined into a matrix and placed into a focal plane array have the following characteristics: low cost, operation at room temperature, compatibility with the silicon CMOS technology, and high detecting performance; therefore recently it became a hot spot in infrared or terahertz detection field. The performance of uncooled infrared focal plane detector arrays depends on the optimization of critical parameters which are determined by geometrical design and the electrical, optical, and thermal physical properties of the detector materials. We report the study of a fabrication process and characterization of two (2D) dimensional arrays of uncooled microbolometers based on silicon (α-Si) thermo-sensing films. Because these arrays substantially reduce sensor size, they are becoming the preferred format for most modern applications

Конструкция и характеристики неохлаждаемых болометрических инфракрасных решеток на основе аморфного кремния

Uncooled bolometric type thermal detectors, combined into a matrix and placed into a focal plane array have the following characteristics: low cost, operation at room temperature, compatibility with the silicon CMOS technology, and high detecting performance; therefore recently it became a hot spot in infrared or terahertz detection field. The performance of uncooled infrared focal plane detector arrays depends on the optimization of critical parameters which are determined by geometrical design and the electrical, optical, and thermal physical properties of the detector materials. We report the study of a fabrication process and characterization of two (2D) dimensional arrays of uncooled microbolometers based on silicon (α-Si) thermo-sensing films. Because these arrays substantially reduce sensor size, they are becoming the preferred format for most modern applications. Неохлаждаемые тепловые детекторы болометрического типа, объединенные в матрицу, размещенную в фокальной плоскости, в последнее время активно применяются в инфракрасном или терагерцовом поле обнаружения, поскольку обладают низкой стоимостью и высокой эффективностью обнаружения, совместимы с кремниевой КМОП-технологией, а также работают при комнатной температуре. Характеристики таких детекторов зависят от оптимизации критических параметров, которые определяются геометрической конструкцией, электрическими, оптическими и тепловыми свойствами применяемых материалов. В статье рассмотрены эксплуатационные характеристики пикселей двумерных массивов неохлаждаемых микроболометров на основе термочувствительных пленок аморфного кремния. Поскольку эти массивы значительно уменьшают размер сенсора, они становятся предпочтительным форматом для большинства современных приложений.

Flow analysis from multiparticle azimuthal correlations

We present a new method for analyzing directed and elliptic flow in heavy ion collisions. Unlike standard methods, it separates the contribution of flow to azimuthal correlations from contributions due to other effects. The separation relies on a cumulant expansion of multiparticle azimuthal correlations, and includes corrections for detector inefficiencies. This new method allows the measurement of the flow of identified particles in narrow phase-space regions, and can be used in every regime, from intermediate to ultrarelativistic energies.Comment: 31 pages, revtex. Published version (references added