نشریه مهندسی مخابرات جنوب
پیاپی 31 (بهار 1398)

In recent years, Polymer Optical Fibers (POFS) have been widely used for short-distance communication connections and various estimation applications due to their amplifying properties, large core diameter and high numerical aperture. Be that coplagenuria has made them comfortable. Dispersion is one of the issues that affects the performance of polymer optical fibers and affects and limits the maximum transmission distance and information transfer capacity. For this reason, the study of the phenomenon of scattering in these fibers has become widespread today. In this paper, the scattering of light intensity is measured, and the far and near field patterns, ie for Field and near Field, are obtained for this light scattering, and simulations are performed using a precise computational model based on the wave tracking method. And the location of the conduction scattering intensity in each polymer optical fiber and the far and near field patterns obtained from the output of these fibers are measured and determined by the simulation results, which is more than the average size of the effective non-uniformities leading to scattering. In optical fibers, they are polymerized at about 200 nm, and these non-uniformities occur at the interface between the core and the shell.

In recent years, methods for timely detection of areas close to voltage instability have been proposed, which, unlike conventional methods, have simpler and faster calculations based on the measurement of local voltage and current phases at bus or grid lines. But some of them do not work well in real networks, so in this article, we will compare the performance of two of these indices and finally show that the performance of the ZL / ZS index is better and more reliable than the Indicator index.

Field Effect Carbon Nanotube Transistor (CNFET) is a promising and new technology that overcomes the traditional limitations of integrated silicon circuit technology. In recent years, the potential of CNFET for analog circuit applications has been exploited. This paper presents a quadratic analog multiplier using CNFETs. designed. The simulation-based on 32nm CNFET technology shows that the multiplier has very low harmonic distortion (less than 0.45%), large input range (±400 mv), high bandwidth (50 ~ GHz) and low power consumption (247 ~ μW), in While at the supply voltage it is ±0.9  volts.

In this paper, a genetic algorithm (GA) is used to automatically design a CMOS analog operational amplifier. Using the proposed method, accurate and optimal values ​​of compensating network elements, device dimensions, voltage and unknown bias currents in the circuit can be obtained. In this paper, MATLAB software is used to perform calculations and implement the computational algorithm, and 0.18µm CMOS technology and HSPICE software are used to simulate the analog integrated circuit. The results show the efficiency of the proposed algorithm in this paper in design Optimally certifies an analog operational amplifier circuit.

This article describes pyroelectric sensors and describes how they work. These sensors are sensitive to temperature changes and generate pulses at the output by switching on and off the heat flux from hot objects in front of them. The advantage of pyroelectric sensors is that they are sensitive to a wide range of infrared waves and operate at ambient temperature. One of the applications of pyroelectric sensors in ground sensors is used in the control of satellites and space structures to determine the position.

The grid database tries to store and scatter data over a wide geographical area in order to create a structure for storing data across the lattice environment in a distributed and heterogeneous manner. Due to the large amount of data, transaction processing in such an environment is very complex and time consuming. Obviously, using queries without optimization will greatly reduce the efficiency of transactions in this database, while using appropriate optimization algorithms can greatly increase efficiency. Many algorithms have been proposed to optimize queries, but due to the different network environments, different optimization algorithms are needed. This paper presents an algorithm that is consistent with the structure of lattice computing and works well in lattice database systems with high data volumes.