Volume 19 (2019): Issue 1 (April 2019)

Frequency hopping spread spectrum (FHSS) communication systems offer significant performance advantages in view of their low probability of intercept, improved performance in multipath fading environments and their ability to avoid interference by hopping into low interference frequency channels. For the transmitted sequence to be correctly received and demodulated, the frequency hop sequence used at the receiver should be similar to that employed in the transmitter. Code acquisition infrequency hopping attempts to address this problem by providing a frequency hop pattern at the receiver that is nearly identical to that used at the transmitter. Code acquisition brings the alignment between the transmitter and the receiver hop pattern to at least one hop period. The main objective of this paper is to design and demonstrate a FHSS code acquisition method. The type of channel used is Additive White Gaussian Noise (AWGN).

Due to the ISM band being unlicensed for communication applications, a lot of applications have been developed in this band and a good example is WiFi IEEE802.11a, b, g, n of Bluetooth. This numeracy of applications motivated this paper. The paper is concerned with the design of a low distortion 20dBm 2.4GHz class-J power amplifier (PA) since PAs are indispensable in radio communications. The design is based on the AVAGO ATF-52189 transistor with a transition frequency of 6GHz. The design is done as a hybrid circuit network realized using microstrip elements and surface mount device (SMD) capacitors. The schematic design, and simulation are carried out using Keysight’s Advanced Design System version 2016.01. The simulated PA exhibited a drain efficiency of 69% and a power output of21dBm.

Direct sequence spread spectrum (DSSS) communication systems offer significant performance advantages in view of their low probability of intercept, improved performance in multipath fading environments and their ability to avoid interference by spreading the signal over a wide bandwidth hence distributing the power. For the transmitted sequence to be correctly received and demodulated, the spreading sequence used at the receiver should be similar to that employed in the transmitter. This paper utilizes MATLAB Simulink to demonstrate a method of synchronizing the code clock at the receiver with the code clock at the transmitter. This fine alignment process is knownas code tracking.

Electrical transformers are essential parts of power supply networks and it is important that their life-time to be preserved. The inrush current of this devices could determine malfunctioning of the transformers or even others component of the network. For this reason, determining the inrush current for single-phase transformers is an important issue in power quality analysis of electrical grids. In this paper we presented an experimental device (hardware set-up and software program) that can measure this in rush current features for small transformers (up to 10 kVA). Also, the device affords the users to measure inrush current knowing the geometry of the transformer, the dimensions and the magnetic characteristic of the core.

To expose humans to microwave emissions damages biological welfare. For measuring the dielectric properties of biological tissues, it was studied whether current safety standard recommendations are inappropriate as far as human blood function is concerned. Thirty age and gender matched blood samples will serve as control. For increased accuracy detection of any possible alteration and to help orientate towards the details that are to be studied ultra-structurally, a special stain was used. An electronic microscope analysis will be performed on all the blood samples after specific preparation to see whether such microwave exposure might affect the ultra-structure of the blood cells. After modeling and sectioning the blocks were contrasted using acetate-uranyl and lead-citrate and study them with an electronic microscope. The obtained images are processed using Viewer Imaging Analysis software for further analysis. In the end, scanning microscopy must be used in order to detect any surface dimorphisms that might appear due to the microwave exposure.

Solar energy is increasingly becoming commonplace in the society with the ever rising electricity bills and reduction in price in solar equipment. Being an “essentially free” form of energy it is necessary to contribute to developments that support or improve the solar energy sector. This paper presents a way to monitor the voltage, current and power output from a solar panel, with the aim of monitoring and projecting the output from a solar farm.

The paper proposes the development of a guitar audio amplifier that is made from a low-priced IC LM386 chip, this amplifier can also be used for radios and other electronic projects IC LM 386 is a reliable and versatile chip that can be used even to make an oscillator that can output sine or square waves. The purpose behind developing this guitar audio amplifier is to offer an easy and economical way to build a good sounding amplifier.

The power cables passing through penetration leads to growth of the thermal ageing mechanisms rate. The paper presents the results of the laboratory tests when the real environmental service conditions for penetration are simulated comparison with the result of the thermal computation of the power cables heating and of the temperature influence evaluation of temperature increase of the power cable components on the cable lifetime. For this particular case, a power cable with PVC insulation, we estimated a lifetime decrease about 20 years referring to lifetime (30÷40 years) for location in air.

Turbo coding is a very powerful error correction technique that has made a tremendous impact on channel coding in the past two decades. It outperforms most known coding schemes by achieving near Shannon limit error correction using simple component codes and large interleavers. This paper investigates the turbo coder in detail. It presents a design and a working model of the error correction technique using Simulink, a companion softwareto MATLAB. Finally, graphical and tabular results are presented to show that the designed turbo coder works as expected.

In this article we present some simulation models regarding the occurences that affect the quality of the electricity supplied to a low voltage consumer. We believe that these will offer to the researcher the opportunity to simulate power quality deviations in different energy system models, thus providing a picture regarding the way those deviations propagate and behave, creating a few basic patterns for studying the energy quality, also taking into consideration the limitations of the system in respect to the software used and the human factor performing the research.

Developing Artificial Intelligence is a labor intensive task. It implies both storage and computational resources. In this paper, we present a state-of-the-art service based infrastructure for deploying, managing and serving computational models alongside their respective data-sets and virtual environments. Our architecture uses key-based values to store specific graphs and datasets into memory for fast deployment and model training, furthermore leveraging the need for manual data reduction in the drafting and retraining stages. To develop the platform, we used clustering and orchestration to set up services and containers that allow deployment within seconds. In this article, we cover high performance computing concepts such as swarming, GPU resource management for model implementation in production environments with emphasis on standardized development to reduce integration tasks and performance optimization.

The introduction of the electric energy in more and more diverse applications currently represents an evolution which is considered normal, taking into account the durable development concept, which are required among the decision makers, and also due to the fact that the oil and gas resources are not evenly distributed in the world, and those who do not have these resources look for solutions to provide them a certain independence over those who have resources. One of the technical solutions, available on Earth, is currently represented by the renewable energy sources. Their usage in the field of the electric automobile charging, is both an economic and technical challenge. Technical solutions are available, and they are developing, but their industrial application is related to an economic strategic approach and a systemic one, which are treated below.