• Energy Research
• other engineering and technologies close
• Serbian close

In this paper possibility of corrosion protection of copper was investigated in acidic media using inhibitors. Inhibitor properties of 5-(4'-isopropylbenzylidene)-2,4-dioxotetrahydro-1,3-thiazole, (IPBDT) was tested on copper corrosion in acidic sulfate contains solution (0.1 moldm-3 Na2SO4, pH=2). Using potentiostatic polarization measurements, inhibitor efficiency of IPBDT in a function of concentration was determined. It was found that in investigation range, increasing of inhibitor concentration results better efficiency of IPBDT. The obtained results also show that IPBDT derivative acts as the mixed inhibitor on copper corrosion in acidic media. During corrosion process, inhibitor molecules are adsorbed on the metal surface following mechanism of Langmuir isotherm.

The main focus of this paper lies with the national laws of three European countries (Germany, Austria and Hungary), as well as the EU law, relating to liability for damage caused by nuclear plant. The aforesaid European countries have enacted legislation prescribing stringent rules on liability of the operators of nuclear plants, meaning that for some forms of legally recognized harm (death, injury, damage to health) the operator incurs liability, even if damage was caused by force major. This type of strict liability, whereby force major is not reason for exculpation, provided that the damage could be related to functioning of the plant, is named absolute liability. In addition, some regimes introduce presumption of causality, when it is more likely than not that damage resulted from the effects of nuclear plants (or ionizing radiation, or secondary nuclear waste materials). The author also analyzes national and European rules on prevention of nuclear and other environmental damage, which includes the creation of the registry of nuclear plants with relevant data on domestic and European operators, the mechanisms of control of the operators, the requirement of preliminary ecological analysis in the construction of new plants, etc. In addition, the author observes differences between nuclear damage in broad and in narrow sense. The former is, in principle, redressed generally, to the extent possible. The latter is commonly redressed individually, to the extent prescribed by statutes.

As a part of reconstruction of the equipment for electrolytic refining in Mining and Metallurgy Institute Bor, a new control system was introduced. The system is based on microcontroller and PC. This system provides automatic control and timely transfer of informations about the status of all important process parameters to process operators. Supervision of the process can be performed locally, or from a remote location through a local area network or over the Internet. The control system provides automatic monitoring and recording of cell voltages, electrolyte temperatures, and automatic control of the heaters. In case of exceeding the given boundary conditions system generates alarm messages. Now, after application of the control sistem, the reliability of electrolytic refining process is improved and insight into the status of process parameters is better.

The protection of wood elements in the exterior use, such as window frames and doors, can be performed with various type of coatings. The most diffused in use are conventional coatings – solvent-based (alkyd, modified alkyds etc.). Last years, because of the restrictive normative regarding the solvent emission, the trend of coatings development leads to the reduction of volatile organic components. Organic solvents are reduced or substituted by environmentally safer solvents such as water or aliphatic solvents. Water based coatings are in constant development. Besides the reduced solvent emission, water based coatings have many other advantages, as well as some disadvantages in comparison with classic, solvent type of coatings. In this paper, the characteristics of water based (acrylic dispersions) and urethan modified alkyd coatings are analyzed and compared.

In this paper, we presented an approach to simulation of magnetic levitation system using nonlinear autoregressive neural network. First, the model of this highly nonlinear system is described and after that the NARX model of neural network is given. Also, numerical optimization techniques for improved network training are described and obtained experimental results from NARX network trainings are shown. It is verified that NARX neural network can be successfully used to simulate real magnetic levitation system. In future works, it can be useful for design of different control algorithms.

Biodiesel, an alternative to fossil fuels, consists of alkyl, usually methyl, esters of fatty acids (FAME). Conventionally, it is mostly obtained by homogeneous base catalyzed methanolysis of edible oils. Despite the significant advantages, the main drawbacks of this process are the high requirements in terms of the quality of the raw materials and environmentally unfavorable processes of catalyst separation and products purification. For these reasons, the researches of biodiesel synthesis are aimed at developing new processes that are economically and environmentally acceptable. In this paper processes of FAME synthesis, their advantages, disadvantages and opportunities for improving are analyzed, in order to develop processes suitable for industrial applications. The main aim was to present an overview of the researches in developing biodiesel synthesis providing a high FAME yield, which are environmentally-friendly and economically acceptable. Heterogeneously catalyzed process has most often studied, aiming at developing catalytic active, stable and cheap catalysts as well as at process improvement. The developments of enzyme and noncatalytic processes are mainly aimed at reducing production costs and increasing the FAME yield under mild reaction conditions, respectively. Generally, the perspectives of biodiesel synthesis include the use of continuous processes and suitable reactor systems.

The paper presents the results of in vitro studies of the possibility of using waste plant materials: biomass of aquatic weed Myriophyllum spicatum (Eurasian watermilfoil or spiked watermilfoil) and fruit stones (peach and sour cherry) in a natural and chemicaly modified form, as a potential biosorbents of different mycotoxins. Biosorption indexes were examined at pH 3.0, 6.9 or 7.0, respectively in electrolite 0.1 M K2HPO4. The highest biosorption indexes of aflatoxin B1 (AFL B1) were determined by algae M. spicatum (94.70 and 96.00%, respectively). Unmodified peach stones binded less quantities of AFL B1 (73.30 and 80.00%, respectively) while sour cherry stones adsorbed the smallest quantity af applied AFL B1 (58.82 and 41.18 %, respectively). The values of biosorption for ochratoxin A (OTA) varied a grait deal, dipending on the biosorbent type and pH values (20.00­76.20%). The best affinity to vomitoxin (DON-in), was observed by unmodifiedpeache stones (50%), at pH 6.9, and for zearalenone (ZON) by M. spicatum (70 and 75%, respectively). Binding of diacetoxyscirp enol (DAS), although much weaker, was recorded at both pH values of applied electrolite by modified peache stones (16.67 and 33.33%, respectively) and modified sour cherry stones (16.67%). Equally good affinity for T-2 toxin was found in modified peache stones, and unmodified and modified form of sour cherriy stones (50.00 and 40.00%, respectively); at lower pH value (3.0) adsorption of this mycotoxin was more pronaunced. Presented results indicate that the tested waste biomasses, in the natural or modified form, were effective biosorbents of different mycotoxins with the highest affinity for AFL B1.

Application of metalworking fluids (MWF) in metalworking processes generates MWF aerosol/mist. Chronic exposure to this aerosol can cause serious health problems to workers such as asthma, lipoid pneumonia, dermatitis, cancer. In this paper behavior of MWF aerosol was investigated. The investigation was done in the pipe, which simulates ventilation system. The aerosol generated from 6 % O/W emulsion was investigated, as well as aerosol generated from water. SHP and water aerosol were generated by laboratory aerosol generator. Behavior of aerosol under four different air velocities was investigated. The aerosol properties were measured by optical particle size analyzer. The obtained results should be of great help for designing filters for mist separation in order to protect workers and the environment.

Three alkyd resins based on ricinoleic acid (30 wt. %), phthalic anhydride and three polyols (glycerin, trimethylolpropane or ethoxylated pentaerythritol) were synthesized. Baking enamels were prepared by mixing the synthesized alkyds with commercial hexamethoxymethyl melamine resin (weight ratio of 70:30 based on dried mass). After the homogenization at room temperature, a thin layer of the resin mixture was applied on a glass panel. Curing of coating films was performed in an oven at 150 °C for 1 h. Dynamic mechanical analysis (DMA) was used to determine glass transition temperature of cured films. The values of the storage modulus, loss modulus and loss tangent were determined in temperature range from −30 to 120 °C. According to the height of the storage modulus rubbery plateau, it is possible to obtain the cross-link density of cured resin mixtures. The film properties (thickness, adhesion, gloss, hardness, flexibility, impact resistance and methyl ethyl ketone resistance) were also investigated. The mixtures of synthesized alkyds resins and commercial hexamethoxymethyl melamine resin (weight ratio 70:30) could be successfully used as baking enamels.

Carbon microsphere has been synthesized by the hydrothermal carbonization of the fructose varying the concentration of the aqueous fructose solution, solvent, pH, temperature treatment and reaction time. Carbon microspheres were characterized by, X ray diffraction, scanning electron microscopy and nitrogen adsorption/desorption isotherms measurements. Carbon microspheres with different diameter were obtained. It was noticed that all mentioned process parameters affected structure and adsorption characteristics of obtained carbon material.