Amplify-and-Forward Relaying in Two-Hop Diffusion-Based Molecular Communication Networks

This paper studies a three-node network in which an intermediate nano-transceiver, acting as a relay, is placed between a nano-transmitter and a nano-receiver to improve the range of diffusion-based molecular communication. Motivated by the relaying protocols used in traditional wireless communication systems, we study amplify-and-forward (AF) relaying with fixed and variable amplification factor for use in molecular communication systems. To this end, we derive a closed-form expression for the expected end-to-end error probability. Furthermore, we derive a closed-form expression for the optimal amplification factor at the relay node for minimization of an approximation of the expected error probability of the network. Our analytical and simulation results show the potential of AF relaying to improve the overall performance of nano-networks.Comment: 7 pages, 6 figures, 1 table. Submitted to the 2015 IEEE Global Communications Conference (GLOBECOM) on April 15, 201

Feedback-Aware Precoding for Millimeter Wave Massive MIMO Systems

Millimeter wave (mmWave) communication is a promising solution for coping with the ever-increasing mobile data traffic because of its large bandwidth. To enable a sufficient link margin, a large antenna array employing directional beamforming, which is enabled by the availability of channel state information at the transmitter (CSIT), is required. However, CSIT acquisition for mmWave channels introduces a huge feedback overhead due to the typically large number of transmit and receive antennas. Leveraging properties of mmWave channels, this paper proposes a precoding strategy which enables a flexible adjustment of the feedback overhead. In particular, the optimal unconstrained precoder is approximated by selecting a variable number of elements from a basis that is constructed as a function of the transmitter array response, where the number of selected basis elements can be chosen according to the feedback constraint. Simulation results show that the proposed precoding scheme can provide a near-optimal solution if a higher feedback overhead can be afforded. For a low overhead, it can still provide a good approximation of the optimal precoder.Comment: 7 pages, 5 figures, to appear at the IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC) 201

Разработка алгоритмов и программных модулей контроля состояния объекта и аналитической обработки данных в распределенной информационно-телекоммуникационной системе

The following article describes the principles and algorithm for data collection, analytical processing and for monitoring the state of different objects in the distributed information-telecommunication system. As a result it improves the efficiency of the system in general and increases the safety level of citizens during emergency situations

A Comparison of Three Approaches to Correct for Direct and Indirect Range Restrictions: A Simulation Study

A common methodological problem in the evaluation of the predictive validity of selection methods, e.g. in educational and employment selection, is that the correlation between predictor and criterion is biased. Thorndike’s (1949) formulas are commonly used to correct for this biased correlation. An alternative approach is to view the selection mechanism as a missing data mechanism. The aim of this study was to compare Thorndike’s formulas for direct and indirect range restriction scenarios with two state-of-the-art approaches for handling missing data: full information maximum likelihood (FIML) and multiple imputation by chained equations (MICE). We conducted Monte-Carlo simulations to investigate the accuracy of the population correlation estimates in dependence of the selection ratio and the true population correlation in an experimental design. For a direct range restriction scenario, the three approaches are equally accurate. For an indirect range restriction scenario, the corrections using FIML and MICE are more precise than when using Thorndike’s formula. The higher the selection ratio and the true population correlation, the higher the precision of the population correlation estimates. Our findings indicate that both missing data approaches are alternative corrections to Thorndike’s formulas, especially in the case of indirect range restriction. Accessed 3,954 times on https://pareonline.net from March 24, 2016 to December 31, 2019. For downloads from January 1, 2020 forward, please click on the PlumX Metrics link to the right

Composition and structure of benzoilacetonates of transition metals and the possibility of their use as gaschromatographic sorbents

The aim of the work was to obtain and study chelate complexes of benzoylacetonates of transition metals, to study their chromatographic properties by the example of mesoporous silica gel modified with benzoylacetonates Co, Ni, Cu, and to establish a correlation between the composition, structure and properties of the materials obtained. To study the physicochemical properties of the complexes and sorbents obtained, modern equipment was used. The composition of the synthesized metal chelate complexes was studied by IR, atomic-emission spectroscopy, gravimetric and elemental analyzes. Chromatographic studies were performed on a gas chromatograph MAESTRO 7820 (Agilent Technologies) with a flame ionization detector. In this work we used metal filled columns 1 m long and inner diameter 3 mm. Results: Sorbents based on mesoporous silica gel modified by intracomplex compounds of benzoylacetonates of cobalt, nickel and copper were obtained. The parameters of gas-chromatographic retention of various classes of organic compounds are determined

Parameter Influences on HVDC Transformer Insulation and Its Link to Conduction Processes

HVDC (high voltage direct current) transmission is an effective way to transport electrical power over long distances by using direct current. The insulation system of HVDC components has to be designed for both AC and DC field distributions. It consists of mineral oil and pressboard. The used insulation material behavior has not been completely understood under DC stress. In this paper, electrical conductivity of pressboard is evaluated and conduction processes are considered. Therefore, conductivity measurements are linked to a number of RC network elements in order to achieve a network model representative for the insulation material behavior under DC stress. Time-constants are determined under different temperatures and different electric field strengths. In addition, the performed simulations provide evaluation of parameters affecting the dielectric behavior of the insulation system oil and pressboard, which are not measured or even cannot be determined by measurement

Parameter Influences on HVDC Transformer Insulation and Its Link to Conduction Processes

HVDC (high voltage direct current) transmission is an effective way to transport electrical power over long distances by using direct current. The insulation system of HVDC components has to be designed for both AC and DC field distributions. It consists of mineral oil and pressboard. The used insulation material behavior has not been completely understood under DC stress. In this paper, electrical conductivity of pressboard is evaluated and conduction processes are considered. Therefore, conductivity measurements are linked to a number of RC network elements in order to achieve a network model representative for the insulation material behavior under DC stress. Time-constants are determined under different temperatures and different electric field strengths. In addition, the performed simulations provide evaluation of parameters affecting the dielectric behavior of the insulation system oil and pressboard, which are not measured or even cannot be determined by measurement

Effect of ischemia on localization of heat shock protein 25 in kidney

Effect of ischemia on localization of heat shock protein 25 in kidney. The effects of renal ischemia on the intracellular distribution of the low-molecular weight heat shock protein (HSP)25 were examined using immunofluorescence microscopy. In all kidney zones, ischemia decreased HSP25 in the supernatant of the tissue homogenates and increased it in the pellet fraction (containing mainly nuclei and cytoskeletal components). This was associated with disappearance of HSP25 staining from the brush border of proximal convoluted tubule (PCT) cells. Because no nuclear staining of cortical tubule cells was apparent either in control or ischemic kidneys, ischemia seems to cause a closer association of HSP25 with cytoskeletal components. HSP25 probably participates in the postischemic restructuring of the cytoskeleton of PCT cells