Journal of Engineering & Processing Management (EPM)
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THE DEVELOPMENT OF MODERN LOW TEMPERATURE FUEL CELLS
Get PDFClassification of fuel cells is presented. Progress in low temperature fuel cells fueled by hydrogen, methanol and formic acid is discussed and the possible future use of fuel cells is indicated. Ethanol is a special fuel because it is available from renewable environmentally friendly sources and its oxidation product (CO2) can be transformed by photosynthesis to ethanol. The design of the anode catalyst for electrochemical ethanol oxidation in the Direct Ethanol Fuel Cell (DEFC) is described in some detail
PROPOSED METHODOLOGY FOR IMPLEMENTING QUALITY METHODS AND TECHNIQUES IN MACEDONIAN COMPANIES
Get PDFProviding quality in a business company is a matter related not only to the work done by individuals, but also with machines and the technology of the production processes as well. Therefore, it is necessary to provide statistical control in terms of estimating both the stability and the capability of production processes as well. However, control solely is not enough. A constant improvement of the processes by reducing the variants is necessary as well. Thus, it comes to the point that using SPC (Statistical Process Control) cannot be a mean of measuring the current performance. Instead, it provides a base for improvement of those processes. While designing the standard operative procedures, a suitable methodology for methods and techniques of SPC needs to be interposed, in order to perform a flawless production and methodology for optimization of costs. This paper provides a methodology proposal of SPC as a subsystem of the TQM (Total Quality Management) system that will assist managers in Macedonia in terms of designing a solid quality system. The proposed methodology provides a solid support of the top management, because the results gained from the outcomes of the partially implemented methods and techniques at some companies in Macedonia indicate that implementing SPC methodology and methodology of costs optimization can help achieving both the defined quality and better productivity by smallest costs. These methods have given same effects in number of diverse companies which refers to the universality of the proposed methodology
ASSESSMENT OF THE THERMAL CONDITION ELECTRIC POWER EQUIPMENT IN PROCESS INDUSTRY BY THE METHOD THERMOGRAPHY
No full textDuring the operation of power equipment in the process industry failure can occur, which if not timely detected and corrected, could lead to major failures and disasters, and a time to unplanned downtime of entire production lines, which can lead to high costs, environmental damage and endanger the safety of workers is therefore within the program of preventive maintenance performed thermographic testing of power equipment. The aim of this is that propose new approach to determine defect of the method of thermography, which is based on determining the method, direction and direction of propagation of heat and temperature profile analysis. This approach allows to prove that the places are not always overheat and malfunction place. Results obtained with this approach are verified by results obtained using UI electrical transient measurements of electrical resistance of joints
WHEAT SAMPLES AND HEAVY METALS
No full textPlants have an important role in circuit of heavy metals in nature. Heavy metals are input into food chains mainly through plants. One of the ways in which heavy metals are input into food products is through contaminated plants and animals used for their production. So, if the plants are cultivated on soil with high content of heavy metals then one part of these metals will be input into their organism. The usage of such plants for domestic animals nourishment will lead to their contamination with heavy metals. Meat, milk and eggs of these animals will be of poor quality considering the high level of heavy metals in them. The other, not less significant way of contamination of food products with heavy metals is the technological process in which they have been made. Namely, due to some irregularities in technological processes it can come to input of certain metals in amounts which are higher than regulated. It can come to contamination by metal particles during its mincing in the mill, by irregular keeping and storage, and as one of the main sources of contamination is the air in the industrial zones. Plants assimilate undesired metals from the soil, and in certain conditions through leaves. These elements are accumulated largely in the root area than in organs above earth. That is the reason why the knowledge of mechanisms of accumulation, distribution and metabolism of heavy metals in plants is of high ecological, scientific and practical significance. Especially because heavy metals are among toxic matters which pollute the environment. This is the reason why wheat is selected for the analysis of the influence of heavy metals on plant culture in this paper. Wheat has dominant role in world’s diet, characteristic of strategic product and it covers significant part (almost one third) of total agricultural area of plants culture planted
RETENTION AND LIPOPHILICITY OF ESTRADIOL DERIVATIVES IN NORMAL- AND REVERSED-PHASE HIGH PERFORMANCE LIQUID CHROMATOGRAPHY
No full textThe retention behaviour and separation ability of some estradiol derivatives were studied by HPLC on silica and C-18 commercially available columns. The mobile phases used were: benzene-ethyl acetate, benzene-tetrahydrofuran, benzene-acetonitrile, isopropanol-water and tetrahydrofuran-water in various proportions. The results are discussed in terms of nature of the solute, eluent and stationary phase. Correlation between the retention constants of estradiol derivatives obtained on C-18 column and log P calculated by program ACD log P was examined too
SUPERCRITICAL FLUID CO2 EXTRACTION ON LICHEN Usnea barbata L.
Get PDFNon-conventional separation procedure - supercritical fluid CO2 extraction (SFE-CO2) conforms to the strict demands of the precise process eco-technologies. It represents a perspective method especially in obtaining eco-friendly extracts from vegetable and animal raw materials. The influence of operating parameters (raw material’ granulation, extraction fluid’ flow rate, operating pressure, operating temperature and extraction time) on the yield of extract and usnic acid, has been studied throughout the extraction process on Usnea barbata L., by application of supercritical CO2 (SFE-CO2). The separation process in all experiments was conducted at operating temperature of 25 °C and operating pressure of 50-55 bar. The extraction of active components from the lichens by supercritical CO2 was performed in a highpressure, extraction “pilot-plant” for processing solid raw materials
THE EFFECT OF ADDITIVES ON α-Al2O3 OCCURRENCE KINETICS DURING HEATING OF INDUSTRIAL ALUMINUM HYDROXIDE
No full textThis paper presents the results of the impact of basic additives in the process of heating (calcinations) of industrial aluminum hydroxide and the formation of the final stable phase α- Al2O3. The influence of additives have been focused on the result of the impact, ie. on the kinetics of crystallization of α-Al2O3, and the comparative analysis of the corresponding activation energies determined for each of the additives used. Based on the experimental results, using a suitable fundamental principles of the Arrhenius equation and suitable statistical tools, it can be concluded about the possible impact of certain quantity additives on the kinetics of the crystallization process, whose results are presented in this paper
THE INFLUENCE OF THE TYPE OF STARTER CULTURE ON RIPENING PROCESSES, PHYSICO-CHEMICAL AND SENSORIC CHARACTERISTICS OF WHITE CHEESE
No full textTraditional starters are used for different types of cheese, a mixed associations of microorganisms. The mixed starters contain more species and strains of bacteria isolated from traditional starters. Depending on the type of cheese are produced, they prevail mesophilous bacteria: Leuconostoc lactis ssp lactis and Leuconostoc lactis ssp cremoris, strains of the genus Leuconostoc or thermophilous: Streptococcus thermophilus, Lactobacillus delbrueckii ssp bulgaricus Lactobacillus delbrueckii ssp lactis and Lactobacillus Helveticus. Starter cultures are used for cheese production for conversion into lactic acid from lactose from milk, decreases with pH value of the middle and have influence on the aroma of the resulting cheese with fermentation of lactose in combination with the degradation of proteins, thus affecting the taste of cheese. Cheese which is obtained by using starter cultures have better organoleptic properties and is more acceptable by consumers. Starter cultures of bacteria are active during the whole process of producing the cheese. In this thesis are considered the most important issues that define the biochemical changes during thirty days ripening of the white cheese obtained with the use of starter cultures. In order to obtain soft white cheese two starter cultures are used: 1.Thermophil starter (Lactobacillus delbrueckii ssp. Bulgaricus and Streptococcus thermophilus) and 2.Mixed starter (Lactococcus lactis subsp. Lactis, Lactococcus lactis subsp. Cremoris, Streptococcus thermophilus and Lactobacillus delbruecki, subspecies bulgaricus). Changes that occur in lactose, protein, moisture content, the content of milk fat, contributes to the formation of aroma and texture of the cheese.Based on the results obtained it can be deferred that the cheese obtained with mixed starter has showed improved sensory features, which means a greater acceptance of the same the consumers
THE USAGE OF MICROWAVE TECHNIQUE TO DESTROY POTATO SAMPLES IN ORDER TO DETERMINE HEAVY METALS BY ATOMIC ABSORPTION SPECTROFOTOMETRY
No full textPreparation of samples by microwave technique consists of large number of phases, from taking samples till receiving homogeneous solution for instrumental analysis. Samples preparation can include combination of drying, wetting, extraction, digestion, analytic separation and solvent removing. The analysis of content of heavy metals in potato from Braničevo Region by the usage of atomic absorption spectrophotometry (AAS) showed that certain samples of potato contain more than 1ppm of lead, and that certain samples contain amount of lead which is even 4 times higher than allowed MDK value. As for cadmium, all samples contains amount which is 7 to even 20 times higher than allowed MDK value. Chrome and nickel are not allowed by Law to be in products for human diet, and by this analysis it is determined that these samples contain chrome (total). In none of these samples was determined the presence of nickel. Received results of the analysis showed that large amounts of chemical (mineral) fertilizers were used at these soils. According to received results it can be concluded that the soil as well as increased usage of phosphate fertilizers are main cause for the presence of heavy metals in potato
INFLUENCE OF PARTICLE SIZE TO EXTRACTION KINETICS OF SAGE BY SUPERCRITICAL CARBON DIOXIDE
No full textSage with different degrees of fragmentation was extracted at the plant for extraction of gases under pressure (HPEP, Nova Swiss, Switzerland). Plant material - drug consisted of dried leaves of sage (Salviae folium), collected from harvested wild plants after flowering (Salvia officinalis L.) in the region of Trebinje during 2007. year. The initial content of extracted substances (q0 = 3.70 g/100g drug) in leaves of sage (Salviae folium) was determined and the kinetics of extraction was tested by determining the content of residual substances in drug (qi, g/100g drug) during the extraction time. From these results the rapid extraction coefficient, b*, slow extraction coefficient, k, and coefficient of internal diffusion, Du, were determined for the assumed forms (plate, cylinder). It is shown that with increasing fragmentation of drugs fast extraction coefficient, b* (0.02 to 0.20) and slow extraction coefficient, k (0.292 to 0.480 h-1 ) are increasing. The value of the coefficient of internal diffusion, Du was decreasing with increasing degree of fragmentation of drugs with 6.11 ·10-8 to 0.35 · 10-8 cm 2 /s for the grist in the form of plate, or with 10.4·10-8 – 0.59·10-8 cm 2 /s for the grist in the form of a cylinder