Volume 6, No. 1 (2016)

STUDY ON DOUBLY-FED ASYNCHRONOUS MACHINE IN REGIME OF GENERATOR

Asynchronous machines with doubly-fed is used mostly as generators in the construction of wind farms. Doubly-fed induction generator can operate on a wide range of wind speeds and obtain maximum power possible for each of its speed. Since the rotor power throughput is lower, the power converters used for supply of the winding rotor will be equal to 25% of the rated power of the asynchronous generator. For the study of doubly-fed asynchronous machine in regime of generator was made an experimental stand in the Electrical Machines Laboratory of the "Vasile Alecsandri" University of Bacau.

EFFICIENT ENERGY CONSUMPTION IN THE DEDICATED EMBEDDED SYSTEMS

Reducing the energy consumption in all fields is currently a continuing concern. Worldwide it has formed a number of entities that seek to encourage the achievement of environmentally friendly electronic products, from several points of view. Given the continued growth of the volume of electronic systems currently used and the planned spectacular expansion in the period ahead, reducing the electricity consumption of the electronic devices and equipment’s is a serious concern in the design of electronic systems. The paper shows how an embedded system used in industrial automation and equipped with a series of energy-saving mechanisms is designed and implemented. For the physical realization of the project a programmable logic array was used because of the flexibility that it offers in the design and implementation of such systems. The mechanisms for energy saving are: power control of the various functional blocks of the embedded system control and the command frequency control of the digital circuits. With an innovative design and a proper control, the embedded functional blocks of the system are placed in the active state or in hibernation, as needed, in order to reduce the electricity consumption. Also, due to the digital character of the component modules it is possible to control the energy consumption by controlling the command frequency of these modules. In this way the modules operate at a variable command frequency, at a high value of the frequency when it increases their request and at a low frequency corresponding to the decrease of the module load. The regime used in order to improve the energy consumption lowers the amount of energy consumed and decreases the temperature and increases the life of the system components. Getting results is done on the one hand in the design phase and on the other hand in the operating of the embedded system. In the design phase, several variants of solving a problem are made available and the designer chooses the most convenient one. In the operational phase the power of the modules and their frequency are controlled. The obtained embedded system is designed to a specific application (dedicated system) for which it was designed, thereby obtaining a maximum desired effect.

OCCUPATIONAL HYGIENE – PERFORMANCE COFACTOR IN POWER ENGINEERING. BIOCHEMICAL RESPONSE TO EXPOSURE TO EXTREMELY LOW FREQUENCY ELECTROMAGNETIC FIELD

Various adverse health effects associated with extremely low frequency electromagnetic field work have been documented in occupational medicine. This study was carried out to investigate the effect of ELF-EMF pollution upon work-environment of electronic equipment repairers. It was evaluated oxidative stress and melatonin hormone levels. In order to study the prevalence of sleep insufficiency and inflammatory markers among electronic equipment repairers exposed to EMF. The electronic equipment repairers are at the highest risk of oxidative stress and an increase in inflammatory markers following sleep insufficiency, which could be explained by lower plasma melatonin levels and higher MDA levels, but not significant changes in monocyte count. Health education about the hazards of ELF-EMF, shortening of exposure time per day, and melatonin supplements could ameliorate the oxidative effect of EMF on exposed workers. Keywords: occupational health, ELF-EMF, oxidative stress, inflammatory markers.

IT’S ENERGY CONSUMPTION SURVEILLANCE TECHNOLOGY (IoT)

With the development of the Internet network, the applications using this global network also developed. Thus, IoT (Internet of Things) technology is developed which means the network linking together the elements of computing and the sensors forming various systems such as smart grids, smart homes, smart transportation, smart cities, etc. Experts estimate that by 2020 there will be over 50 billion objects connected. This paper presents an embodiment of a system of supervision and control of the energy consumption of a home. The main benefits of such a system are many and they include energy saving, local or remote monitoring and controlling, security and protection, obtaining statistical information to optimize the functioning of things, etc. The main issues discussed in the paper include the acquisition of information and its distance transmission via Internet, the command and distributed control in a particular area (e.g. housing), the modality of human-computer interaction and human-entity, the prevention and elimination of the errors and the increase of the operational safety. The paper presents the ways to acquire the information from the supervised environment, the nature of information and the centralization of data for transmission over the Internet. At the same time, the possibilities of the distributed control in the chosen area are analyzed. It then describes how it is possible to make the Internet connection and the data transmission. Ways for the user interaction with the system through a command language or through a graphic system are also discussed. Ensuring the safe operation of such a system is a main component that allows the desired results. The paper presents the methods and techniques used to ensure a high degree of system safety and an adequate supervision of the perimeter. The analysis of the built system that uses such a technology brings many benefits that will surely involve the extension and improvement of the methods and the techniques used.

DESIGNING A SYSTEM FOR STOCK MARKET TRADING ASSISTANCE USING FUZZY LOGIC

In this paper we present the design of a system for stock market trading assistance. The system will provide buy/sell signals. The aim is to maximize the accuracy of such signals, even with the cost of missing some of them. The architecture of the network will be determined using a genetic algorithm and for training differential evolution will be used. The support vector machine will perform a three-class classification (buy/sell/no action). For this, two support vector machines will be used, one classifying buy against don’t buy, and the other one classifying sell against don’t sell.

ANALYZING WIFI NETWORKS USING ELECTRONIC HARDWARE DEVICES

The paper presents the programming and development of a portable device for detecting and analyzing wireless networks. It is able to determine the main parameters of an access point, that is, to be able to set our own access point to achieve maximum performance in wireless data transfer.