Abstract this paper presents a sensorless control approach of inverter dc-bus voltage using extended Kalman Filter (EKF). A positive sequence detection of grid voltage and load current is also proposed. The dc-bus voltage estimated by EKF is combined with the modified instantaneous power (p–q) control technique for photovoltaic system application to improve electrical energy quality at the …
Abstract The harsh operating environments of many electronic systems, such as in the automotive and aerospace applications, make the semi-permanent connector terminal susceptible to intermittent failure or high contact resistance. Fretting, small cyclic movements at the contact interface, is exacerbated by oxidation to cause fretting corrosion, resulting in these types of failures. However, d…
Abstract This paper characterizes the error in distance relay operation due to the existence of asynchronous frequency components when a fault in a line with series compensation occurs. The distance relay model and the impact of nonfiltered frequency components using the conventional digital filters is presented, an errorwill appear in voltage and current fundamental frequency phasors estimat…
Abstract This paper develops a precise proportional–integral (PI) type control system for repeatable tracking control of a permanent magnet synchronous motor (PMSM) under motor parameter and load torque variations. By adding a very simple learning feedforward term, a conventional PI control system can be enforced to have a perfect tracking performance under model parameter and load torque v…
Abstract This paper investigates the operation of a DC microgrid which is connected to a DC distribution network using a modular-isolated bidirectional DC–DC converter. The bidirectional power flowcapability of the proposed modular converter provides the possibility of power exchange between DC microgrid, and DC distribution network contains some microgids. The extendable configuration of t…
Abstract Power transformer protective relay should block the tripping during magnetizing inrush and rapidly should operate the tripping during internal faults. There are a variety of protective relays using different measuring techniques to provide reliable and secure transformer protection. These types of the protective relays include electro-mechanical, solid state, digital and numerical re…
Abstract This paper presents genetic algorithm optimization method with a suitable objective function to determine optimum location and rated values of FACTS devices by taking into account changes in the power system load over time. In this study, annual daily load profile is considered as a whole instead of an instant load profile while looking for optimum size and location of FACTS devices.…
Abstract This paper proposes a new multi-objective dayahead market clearing (DAMC) mechanism with demand response offers, considering realistic voltage-dependent load modeling. This paper presents several objectives such as Social Welfare Maximization including demand response offers (SWM), Load reduction Minimization (PredM), and Load Served Error (LSE) minimization. Energy and demandside r…
Abstract Optimal reactive-power dispatch (ORPD) is one of the most difficult optimization problems regarding to power-system operation which is heavily related to system stability. To overcome ORPD problem, in general, the total real-power loss is reduced by determining the power-system control parameters, such as generator voltages, tap ratios of tap-changer transformers, and compensated rea…
Abstract Single-tuned passive filters offer reasonable mitigation for harmonic distortion at a specific harmonic frequency with a high filtering percentage, but resonance hazards exist. Traditional damped filters offer high-pass filtering for the high-frequency range, but suffer from extra ohmic losses. C-type filters may operate in a manner similar to the tuned filters with lowdamping losses…
Abstract The paper suggests a new procedure for the estimation of the parameters (amplitude and phase) for a complex periodic signal, based on the concept of analytic signal (AS). Starting from the supposition that the signal fundamental frequency has been estimated in advance at an independent stage, new analytical relations are derived for fast calculation of the unknown parameters, entail…
Abstract The paper deals with the influence of a loss of one phase of a feeding source on the properties of a five-phase induction machine. The attention is paid to the waveforms of the currents in individual stator phases, the increase in torque pulsations and the decrease of speed in emergency operation after the disconnection of a faulty phase of the source. Machines in star, pentagon and …
Abstract The efficiency and installation costs of solarpowered drip irrigation systems depend on not only the efficiencies of the electrical motor, its driver, and the pump, but also the efficient usage of irrigation water. In this study, the initial installation costs and energy consumption of photovoltaic irrigation systems were decreased by obtaining the soil moisture level as a reference …
The article aims to present the problems that may arise in the implementation of the cadastral works on stock of wood, works in the extraurban areas, on the political boundaries. Solutions are being looked for as regards the assigned areas that are disintegrated by the boundary between districts, without compromising the law enforcement 165/2013 on the restitution of the abusively confiscated e…
Abstract The application of the XLPE cable under DC stress is now being considered as one of the promising tool for enlarging the limited transmission capacity of the traditional electric power cable due to the several technical advantages. Therefore, many research institutes are trying to improve the performance by carrying out experimental investigations related to the reliability of the ca…
Abstract The formulations employed to the optimization of passive filters can be classified as formulations of a single objective or formulations with multiple objectives. The single-objective formulations normally are devoted to determine the filters of lowest cost that assure the compliance with the power quality standards, while in the multi-objective approaches are added other goals that …
Abstract It has been conventionally believed that there exist 4n variables P, Q, V, θ for an n-bus system in the power flow computation, while we have 2n power flow equations. In this article, the authors argue that the number of variables in an nbus system is not 4n but 4n−1, hence the power flowsolution can be obtained without specifying the reference angle of the slack bus.We then deliv…
Abstract The effect of high photovoltaic (PV) penetration with constant injected voltage on the loss of excitation phenomenon of single machine infinite bus power system with two transmission lines has been investigated. The PV modules are integrated to the power system at the same bus of the synchronous generator via DC–DC buck–boost switch mode converter, three-phase DC–AC switch mode…
Abstract This article deals with the problem of electrical discharge initiation in mineral oil in the setup of insulated electrodes. The results of laboratory experimental studies were collated with the results of the numerical calculations of electrical field stress. Both kinds of the research methods were applied to analyze the two model electrode setups immersed in mineral oil: setup with …
This paper presents a case study on realizing a 3D model of surfaces that will be leveled in order to build a shopping center. In the first phase, devices and methodology adequately used are presented, being adapted specifically to the existing situation on the ground and to the required accuracy for lifting. Results desired in this case study are primarily focused on tracking effectiveness,…
Abstract In the October 2009 issue of this Journal, we introduced a special pot type, which could improve the energy efficiency of induction cooking, make the boiling process faster and the cooking more comfortable. The dissipated power in the new pot was significantly higher than in the traditional ones at any inductor current. In this paper we show another pot type with similar advantages, …
Abstract Today electronic devices require a power supply without any variation or disturbance. Nevertheless, electrical variations presented in power lines are more frequent and powerful. The consequences of poor power quality devices. Thus, in this study, an FMEA is presented to know which electrical variation has more effect on the reliability of electronic devices. The analysis was perform…
Abstract The results of the breakdown time lags obtained by commercial “OSRAM St 111” gas diode are presented. The memory curves for different voltages (for 220, 250 and 300 V) are shown. The analysis of the experimentally obtained distributions (histograms and Laue distributions) for different voltages (for 220, 250 and 300 V) and different relaxation times (from 1 to 1500 ms), as well a…
The purpose of the present paper is to identify viable solutions for organising organic producers groups and supply chains at county level. With this purpose in mind, our research aim was to evaluate which is the best networking solution for 40 organic farmers in Calarasi County. This statistical approach was based on multidimensional scaling and hierarchical clustering methods that permitted u…
In the latest years, researchers have been working to reduce the dependence on petroleum based fuels and products due to the increase in environmental consciousness. This leads to investigate the environmentally friendly sustainable materials in order to replace the existing ones. One of these polymeric materials is poly(3-hydroxybutyrate) (PHB) which is a semi-crystalline, linear polymer belon…
In view of the relatively recent introduction of the chinchilla as an experimental model in human neurological research, there rises a need for a precise knowledge of the anatomy and structure of the different segments composing this species’ encephalon. Our study aimed to enrich the current data pool, by providing a macroscopical and histogical description of the chinchilla’s cerebellum. 1…
Miscanthus giganteus biomass has a very good quality for combustion (similar as a light coal or wood, up to 19.6 MJ/kg dry matter) and has positive ecological impact for marginal land that makes this crop suitable as bioenergy resources for small scale heating systems. The most important technology to make easily available Miscanthus giganteus feedstock on the market is biomass briquetting or p…
The main goal of UNESCO (United Nations Educational, Scientific and Cultural Organization) is to "encourage the identification, protection and preservation of cultural and natural heritage around the world considered to be of outstanding value to humanity" (World Heritage Convention). To date (April 2015), UNESCO World Heritage List consists of 1007 cultural (monuments, group of buildings, sit…
Water is an important factor in the ecological balance. Surface water pollution, due to activities related to the food industry and population growth, is a current problem with serious consequences to human health. Galda River from Alba County, Romania is a medium size river, but strongly affected by the pollution from anthropogenic sources. To restore the ecological balance of this area, the w…
Precise documentation of cultural heritage monuments status is essential for its protection and scientific studies. The digital preservation of cultural heritage monuments is a specially challenging application of 3D modelling. Cultural heritage objects and sites greatly differ from each other and a maximized fidelity of the 3D model is a core requirement. Terrestrial laser scanning is a techno…
Corneal ulcers are the most common ocular disorders encountered in dogs and cats. Melting keratitis is a pathological condition of the cornea that appears when there is an imbalance between proteinases and proteinase inhibitors, components involved in corneal wound healing. Proteolytic enzymes such as collagenases are produced by some bacteria, especially Pseudomonas spp.,fungi (Aspergillus spp…
It was analyzed the behavior of vine varieties with biological resistance in southern climatic conditions of Romania, during 3 years of study. Thus, there were determined: phenology of varieties, fertility and productivity for table varieties and wine varieties, the behavior of these varieties at the attack of the main diseases and phylloxera, physico-mechanical characteristics, the technologic…
In the latest IPCC report (2014) it was estimated that since the mid-20th century, the number of cold days and nights has decreased and the number of warm days and nights has increased in large parts of Europe. Some recent analyses have found that mean summer maximum temperature change over Europe was +1.6 ± 0.4°C during 1880 to 2005. It seems that human influence has contributed to the obser…
The aim of this study was to identify and describe macrospcopic and microscopic liver lesions in pigs necropsied at the forensic discipline during 2 years of study; assessing the hepatopathies prevalence, based on morphopathological criteria (circulatory disorders, dystrophic processes, inflammatory and tumor processes). The study was conducted in the period November 2012 - 90 October 2014. It …
During 2007-2014 has appeared, in the South part of Romania, a pandemic of common voles (field mice), which surprised farmers and authorities and which caused damages of 1,200-2,000 kg/ha on wheat and 1,000-1,700 kg/ha on rape. This enormous pest produced, at national level, damages of over 3 billion RON, i.e. 700 million EURO only in 2014. The knowledge of the problem and the pandemic control…
Soil-transmitted helminthes infections are caused by different species of parasitic worms. They are transmitted by eggs or larvae present in dog faeces, which contaminate the soil. The presence of infective parasitic elements in the environment represents an important way of transmission of intestinally nematodes from dog to human and other animals. They can become infected by accidental ingest…
This paper aims to present the reinvention of rural underground and half buried houses in the context of the 21st century’s raising cost for energy, environmental concerns and landscape alteration by the growing population, together with today’s urban-rural migration. Rural homes, ‘bordei’ type, had an extensive occurrence in Europe and beyond, found in various forms in different geogra…
Fusarium graminearum Schwabe - teleomorph Gibberella zeae (Schwein.) Petch. and F. culmorum (W.C.Smith) Sacc. are the most important head-blighting pathogens of wheat in many regions of the world, including Romania. The strategies developed for the control of Fusarium spp. infections on cereals include agrotechnical practices, resistant cultivars, and fungicides use. However, the toxicity of fu…
The research aims to present the evolution of localized irrigation methods, according to this process the modern equipment will be tested. This study will investigate the technical and economic efficiency compared to the currently used methods in the greenhouse. The study was conducted in the research center Hortinvest, University of Agronomic Sciences and Veterinary Medicine of Bucharest. The …
The current trend to use natural preservatives in food industry had led to the use of essential oils which are natural compounds already known for their antimicrobial and antioxidant activity. The aim of this study is to investigate the in vitro antifungal activity of rosemary essential oil and of some terpenes like eugenol, nerol, limonene (+), limonene (-) and pinene against three strains of…
The introduction of alternative methods in the research, in the diagnosis of diseases and in the production of bio-preparations, led over time to a drastic reduction in the number of animals used for scientific scope in Romania. However, our country has always aligned legislation in this area with the European Union. In this regard, last year was transposed into national law Directive 63/2010 w…
A 11-year-old 3.1 kg, castrated, female Sphinx cat was referred to the Clinic of the Faculty of Veterinary Medicine Bucharest for acute onset vomiting, loss of appetite, anorexia, faintness, sharp breath, inability to exercise, oliguria and lethargy. Results from a complete blood (cell) count (CBC), serum chemical profile, and urinalysis submitted at that time were abnormal. The patient had hyp…
The greatest challenge, as far as landfill designing is concerned, is building a drainage system capable of diminishing the most severe negative effect, i.e., groundwater pollution. Based on waste collection system configuration – drainage conditions for existing landfills, drainage of homogeneity, etc. – the present paper managed to determine the hydraulic conductivity of the drainage laye…
The biosurfactants produced by yeast species belonging to Candida, Rhodotorula and Yarrowia genera present a growing interest due to their applications in food industry, therapeutics, bioremediation and cosmetics. The yeast strain Yarrowia lipolytica CMGB32 was characterized using morpho-physiological observations and PCR-RFLP analysis of the ITS1-5.8S-ITS2 region. The amplicon had 360 bp and t…
A massive Lactococcus lactis ssp.lactis c2 and e72 phage contamination of raw milk burduf cheese was revealed in all analyzed samples. Contamination with c2 phage specific for Lactococcus lactis ssp.lactis C2 is lower than the contamination induced by e72 phage. The contamination level with E.coli and coliforms in the core of burduf cheese was initially high, while the initial Staphylococcus sp…
We evaluated the effect of ketamine-dexmedetomidine-butorphanol (K, 80 mg/kg; D, 0.25 mg/kg, B,0.5 mg/kg) and ketaminemedetomidine-butorphanol (K, 80 mg/kg; M, 0.25 mg/kg, B,0.5 mg/kg) administered intraperitoneally, during anesthesia and immediate recovery post surgical phase, in male Wistar Outbreed rats undergoing surgery for free graft sciatic nerve transplantation. Recovery was determined …
Fish eustrongylidosis is a parasitic disease involving 3rd and 4th stages larvae of the Eustrongylides nematode (Ph: Nemathelminthes). Over the past 20 years, the number of case reportings on fish eustrongylidosis has increased, especially within industrial fisheries and amongst fishermen. Recent data have confirmed the tendency of a spatial extension of the parasite distribution area towards …
The objective of the paper is the investigation of the livestock facility response, in the specific conditions of seismicity of Romania. All buildings are designed for a particular use, and this is reflected in their shape, size and layout. The design and development of a traditional livestock facility can provide important information about agricultural or industrial practices in the past. Sma…
The current paper presents the original results regarding a software programme for production and reproduction data management in dairy farms, used also in the accounting department and in the genetic breeding of bovine herds. A management system database - SGBD - which assures the independence of logical correlations between dates and their minimum redundancy - was used for this purpose. This…
This study aimed to explore the situation of native chickens development in the tropical humid regions especially in Minahasa regions, Nord Sulawesi Indonesia. The survey method was used in 122 farmers selected by sampling purposive design. The results show that in general the farmer in small scale has only under 40 chickens with high risk of dangerous diseases on their animals, exclusively th…