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Research in Astronomy and Astrophysics 2019年第1期19卷 141-148页

作者： Diana P.Kjurkchieva Velimir A.Popov yordanka eneva Nikola I.Petrov Department of Physics and Astronomy Shumen University Medical University Institute of Astronomy and NAO Bulgarian Academy of Sciences

We present photometric observations in Sloan filters g′, i′of the eclipsing W UMa stars USNOA2.0 1350-17365531, V471 Cas, V479 Lac and V560 Lac. The sinusoidal-like O-C diagram of V471 Cas indicates the presence of a third body with mass 0.12 M_⊙(a red dwarf) at distance 897 R_⊙. The O-C diagram of V479 Lac reveals a period decrease of d P/dt =-1.69 × 10-6d yr-1. The results of the light curve solutions are:(i) the targets are overcontact binaries with small fill-out factors;(ii) their components are F–K stars, comparable in size, whose temperature differences are below 80 K;(iii) all targets undergo partial eclipses and to limit the possible mass ratios we carried out two-step q-search analysis. The target global parameters(luminosities, radii, masses) were obtained on the basis of their Gaia distances and the results of our light curve solutions. The obtained total mass of V560 Lac turns out to be smaller than the lower mass limit for presently known W UMa binaries of 1.0-1.2 M_⊙, i.e. this target is a peculiar overcontact system.

关键词： binaries:close binaries:eclipsing methods:data analysis stars:fundamental parameters stars:individual(USNO-A2.0 1350-17365531,V471 Cas,V479 Lac,V560 Lac)

Elasticized Knitted Structures-Fabric Thickness, Knapton Constant and Thickness Interlacing Factor

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材料科学与工程（中英文A版） 2011年第6期1卷 801-811页

作者： Alenka Pavko Cuden yordanka Angelova Department of Textiles Faculty of Natural Sciences and Engineering University of Ljubljana Slovenia Department of Textile Machines and Technologies Technical University of Gabrovo Bulgaria

Knitted fabrics are complex and dimensionally sensitive structures. Minor variations to the basic parameters significantly influence the performance and comfort properties of knitted fabrics, as well as the planning for their manufacture. Fabric thickness is a vital parameter of knitted fabrics, influencing insulation properties; air permeability; protection from UV radiation; handling characteristics; material consumption etc. The research objective was to examine comparatively, the thickness of knitted fabrics, made from yarns with an elastane core and from conventional yarns, without incorporated elastane. The knitted samples were made from viscose and polyacrylonitrile yarns, in basic single and double knitted structures: single jersey; single cross-miss; single half-cardigan; single full-cardigan; 1 × 1 rib and 1 × 1 purl. The fabric thickness of each structure was measured at various loadings of pressure foot. From the polynomial equations of pressure loading-thickness trend line, the knitted fabric thickness T0 at zero loading, was calculated for each knitted structure. The Knapton constant K5, which assigns the relationship between knitted fabric thickness and the yarn diameter, was also studied for elasticized and non-elasticized structures. A new parameter, fabric thickness interlacing factor was defined as a result of these studies.

关键词：结构厚度针织面料弹力因子交错面料结构绝缘性能针织结构

Determination of the Place of Implementation of a Biorefinery Based on Logistics Parameters

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Journal of Power and Energy Engineering 2022年第5期10卷 22-38页

作者： Shara K. M. J. Leal yordanka R. Cruz Vinicius Rossa Gisel Ch. Díaz Yedier R. Padrón Donato A. G. Aranda Rene G. Carlíz School of Chemistry Federal University of Rio de Janeiro Rio de Janeiro Brazil Institute of Chemistry Fluminense Federal University Niterói Brazil

Airlines and the aviation industry are committed to emission reduction targets. Biokerosene was pointed out as one of the key elements to achieving this goal. The use of oilseeds in the production of biokerosene is interesting due to the great Brazilian experience in the production of biofuels from this raw material. In view of this scenario, this dissertation has as its main objective the definition of the place of implantation of a biorefinery in Brazilian territory that has aviation biokerosene as its main product. For this, data on supply and demand for fossil aviation kerosene in Brazilian regions were collected, an extensive review was carried out in scientific articles on the oleaginous raw materials used for the production of this biofuel, and logistical parameters were selected and used as criteria for that selection. The oilseeds selected for the production of biofuel were macaúba and soybean and the state was chosen for the implementation of the biorefinery was Goiás. Based on logistical parameters, the city of Formosa (GO) was selected to host the biorefinery. The soybean crushers located in Luziania, Anápolis, Ipameri, and Itumbiara were chosen as suppliers of soybean oil and the city of Formosa (GO) as the headquarters for the commercial planting of macaúba. The destination of this fuel will be Petrobrás Distribuidora S.A., an aviation fuel distributor authorized by the ANP based in the city of Brasília (DF).

关键词： Biokerosene Biofuels Oilseeds Biorefinery Aviation

Characterization of the Lipid Components in Desmodesmusand ScenedesmusStrains: Lipid Content, Lipid Classes and Fatty Acid Profile

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American Journal of Plant Sciences 2020年第12期11卷 2103-2121页

作者： Carolina Vieira Viegas Gisel Chenard Díaz yordanka Reyes Cruz Leonardo Brantes Bacellar Mendes GREETEC Laboratory Federal University of Rio de Janeiro (UFRJ) Rio de Janeiro Brazil CENPES/PETROBRAS—Leopoldo Américo Miguez de Mello Research Center Rio de Janeiro Brazil

The lipid composition in terms of the amount of neutral lipids, free fatty acids and polar lipid content is of great importance to make full use possible of this fraction and to define the suitability of its application, either as a raw material for fuel production, nutraceutical purposes or feed. In addition to the fatty components present in the lipid extract, other components may be included, such as: carotenoids, pigments and sterols. The microalgae studied in this work, Scenedesmus sp. and Desmodesmus sp., were subjected to the same growth conditions and evaluated for lipid content, quantification and diversity of lipid components as well as its fatty acid profile. For lipid determination two extraction methods were compared: the J: Schmid-Bondzynski-Ratzlaff and Bligh & Dyer method. For Desmodesmus sp. 5.43% ± 0.41% and 9.18% ± 0.33% of lipids were obtained on an ash-free dry weight basis and for Scenedesmus sp. 12.46% ± 0.38% and 8.16% ± 0.42% of lipids were obtained on an ash-free dry weight basis using for both methods J:

关键词： Microalgae Desmodesmus sp. Scenedesmus sp.

Hydroesterification of Nannochloropsis oculatamicroalga’s biomass to biodiesel on Al2O3supported Nb2O5catalyst

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Natural Science 2012年第4期4卷 204-210页

作者： Angel Almarales Gisel Chenard Roberto Abdala Donato A. Gomes yordanka Reyes Neyda Om Tapanes Ecology Department University of Málaga Málaga Spain GREETEC Laboratory Federal University of Rio de Janeiro Rio de Janeiro Brazil Materials Laboratory West Zone State University Center (UEZO) Rio de Janeiro Brazil

Hydroesterification process has been presented biodiesel production from oil the green microalga Nannochloropsis oculata raw materials. Biodiesel studied in this work is the main product got from the hydroesterification of biomass the Nannochloropsis oculata and was obtained from esterification of fatty acid (product of a hydrolysis reaction) with methanol. It was used as catalyst the niobic acid pure and supported on δ-aluminum. The product was evaluated by gas chromatography and other analyses. The optimum conditions found in the conversion (%) for the hydrolysis reactions of the biomass (92.3%). Better results were observed in the algae concentration 20%, lead at 300?C with 20% of catalyst. For esterification of fatty acids of Nannochloropsis oculata (92.24%), were observed the molar ratio methanol: fat acid 3, lead at 200°C with 20% of catalyst supported.

关键词： Biodiesel Microalgae Hydrolysis Esterification Nannochloropsis oculata

Biodiesel Production Based in Microalgae: A Biorefinery Approach

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Natural Science 2015年第7期7卷 358-369页

作者： Lauren Espinosa González Gisel Chenard Díaz Donato Alexandre Gomes Aranda yordanka Reyes Cruz Mariana Monteiro Fortes Greentec Laboratory School of Chemistry Federal University of Rio de Janeiro Rio de Janeiro Brazil Grand Valle Bio Energy Ltd. Biodiesel Factory Porto Real Rio de Janeiro Brazil

It is of great knowledge nowadays that the use of fossil fuels is responsible for the emission of gases that intensify the greenhouse effect, which threatens the survival of the humankind. The gravity of this fact could be mitigated through the indirect use of solar energy for fuels derived from vegetable that can be planted and cultivated by the world of renewable and non-polisher. Microalgae play an important role in this regard, as they have promising characteristics as potential raw material for the production of biofuels, able to absorb large amounts of CO2. Chlorophyll organisms convert these simple substances in the atmosphere, absorbing sunlight into chemical energy stored, that is, compounds with high energy, biomass can also be used to obtain biocompounds human nutritional supplement and food animal, however, have been found an important number of difficulties to economically viable production like high cost of production of dry biomass and oil extraction. Here, we review the main approaches of biorefinery concept appearing as an alternative to achieve economic viability of the production of bio-diesel based on microalgae. The major points are the following: 1) use of re-residual water, 2) marketing of Carbon Credits, and 3) development of co-products resulting from high value added.

关键词： Biodiesel Biorefinery Microalgae

Quantification of Lipid Content and Identification of the Main Lipid Classes Present in Microalgae Extracts Scenedesmus sp. for Obtaining Fatty Compounds for Biofuel Production

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Energy and Power Engineering 2020年第6期12卷 273-287页

作者： Carolina Vieira Viegas Leonardo Brantes Bacellar Mendes Rafael Richard João Gisel Chenard Díaz Donato A. G. Aranda yordanka Reyes Cruz GREETEC Laboratory Federal University of Rio de Janeiro (UFRJ) Rio de Janeiro Brazil CENPES/PETROBRáS—Leopoldo Américo Miguez de Mello Research Center Rio de Janeiro Brazil

Microalgae biomass has been reported in the literature as one of the most promising sources for obtaining different products of industrial interest such as lipids, fatty acids, carotenoids, proteins and fibers. The lipid fraction of microalgae comprises neutral lipids, free fatty acids and polar lipids. It is of great importance to estimate the composition of the lipid fraction to define the potential for use, either as a raw material for the production of biofuels or for use for nutraceuticals and/or food purposes. The microalgae Scenedesmus sp. cultivated in a photobioreactor, the sky open raceway type, was evaluated for lipid content, identification and quantification of lipid components obtained from different extracts. In the quantification of the lipid content, extraction methods were proposed without chemical treatment (use of solvents only) such as chloroform:methanol (2:1 v/v)—Bligh & Dyer, Ethanol, Ethyl acetate:Hexane (1:1 v/v) and others with chemical treatment such as J-Schmid-Bondzynski-Ratzlaff (acid) and saponification (basic). For the identification of the main lipid components present in the extracts, the Thin layer chromatography (TLC) technique was used. Th

关键词： Microalgae Lipids Extraction Saponifiable Compounds Biofuels

Photobioreactor of Microalgas for CO_(2) Biofixation

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Journal of Power and Energy Engineering 2019年第1期7卷 91-106页

作者： yordanka Reyes Cruz Gisel Chenard Díaz Andreina Z. Figuera Leonett René Gonzalez Carliz Vinicius Rossa Luciano Basto Oliveira Maurílio Novais da Paixao Donato Alexandre Gomes Aranda School of Chemistry Federal University of Rio de Janeiro (EQ/UFRJ) Rio de Janeiro Brazil Faculty of Chemical Engineering Federal University of Uberlandia (FEQUI/UFU) Minas Gerais Brazil International Virtual Institute for Global Change (IVIG/COPPE/UFRJ) Rio de Janeiro Brazil

Microalgae are unicellular organisms capable of photosynthesis, turning sunlight and carbon dioxide (CO2) into rich biomass. Precisely because of this definition, in recent years various sectors have been targeting their ability to reduce CO2 emissions and the capacity of simultaneously synthesize biomass which can be later used to produce bio-fuels. Besides being considered fast-growth microorganisms, microalgae have a diverse biochemical composition with similar characteristics to traditional biomass. In this context, the present work aimed to evaluate the biofixation of CO2 by the microalgae Monoraphidium sp., cultivated in a closed-window type photobioreactor, as well as characterization of microalgal biomass produced in relation to the total lipid content (TL), lipids converted into biodiesel (LCB), carbohydrates and proteins. The results achieved showed that the best result was obtained after 24 h of cultivation, where for each gram of biomass produced approximately 1.2 g of CO2 were consumed. In the growth phase the average biomass productivity in the Janela photobioreactor was 58 mg·L-1·day-1 concluding that microalgae culture systems could be coupled to the chimneys of large industries emitters CO2 using this gas, resulting from combustion processes, in the process of photosynthesis. The biomass Monoraphidium sp. produced had a content of lipids converted into biodiesel of approximately 8.36% ± 2.69%, carbohydrates 32% ± 3.37% and proteins 34.26% ± 0.41%.

关键词： Biomass CO_(2) Capture Cultivation Microalgae Photobioreactor

Primary Separation of Antioxidants (Unsaponifiables) the Wet Biomass Microalgae Chlamydomonassp. and Production of the Biodiesel

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Natural Science 2014年第15期6卷 1210-1218页

作者： Gisel Chenard Díaz yordanka Reyes Cruz Mariana Monteiro Fortes Carolina Vieira Viegas René González Carliz Nelson C. Furtado Donato A. Gomes Aranda Greentec Laboratory School of Chemistry Federal University of Rio de Janeiro Rio de Janeiro Brazil Brazilian Center for Physical Researches Rio de Janeiro Brazil

This work studies the saponification which directs the wet biomass of algae Chlamydomonas sp. like a previous stage to production of biodiesel. This stage allows the obtainment of fatty acids to produce biodiesel, instead of the gross lipid fraction. In addition of the fatty acids, utilizing the same process one can also obtain the fraction unsaponifiable, these are soluble in apolar solvents and contain mainly carotenoids that can take action as antioxidants and photoprotectors, as they reduce the oxidation of unsaturated fatty acids. The saponification direct and extraction of fatty acids from biomass is faster and reduces the time and cost of operation. The separation of unsaponifiable matter from the biomass humid of microalgae Chlamydomonas sp., was held according to the method AOCS (Ca 6a-40), using extraction Liquid-liquid with hexane as solvent. Subsequently, phase hydroalcoholic or from soap, containing fatty acids, was acidified by addition of H2SO4 and the fatty acids were recovered by the addition of hexane. After acidulation of the soap, necessary for obtaining of the fatty acids was performed the stage of esterification for obtaining of biodiesel. The operating conditions were: molar ratio fatty acid:methanol (1:10), as catalyst 8% H2SO4 calculated in relation to the mass of fatty acid, 200℃ and reaction time of 90 minutes. The content of methyl esters was 96.8% determined by gas chromatography according to standard EN14103. The quality of biodiesel produced from wet biomass of Chlamydomonas sp. is according to the specification established by standard EN 14214 and RANP No. 14. For the identification of the composition the unsaponifiable fraction was used the method of High Performance Liquid Chromatography (HPLC). The composition of the material unsaponifiable found was of: Carotenoids total (0.76%);Lutein (0.45%);Zeaxanthin (0.07%);α-carotene (0.05%);β-carotene (0.11%);13 cisβ-carotene (0.05%) and 9-cisβ-carotene (0.03%).

关键词： Biodiesel Unsaponifiables Esterification

Simulation Models for Evaluation and Selection of Depreciation Policy for Agricultural Companies in the Republic of Bulgaria

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Journal of Modern Accounting and Auditing 2013年第10期9卷 1322-1333页

作者： Ivanka Borisova Dimitrova yordanka Velcheva "Angel Kanchev" University of Ruse Ruse Republic of Bulgaria

In the present paper, the results from research on the influence of criteria (factors) such as depreciation method, materiality threshold, and inflation rate on the selection of depreciation policy are shown. The research has been carried out with the help of specifically devised simulation models. The simulation is realized in accounting for the unevenness of money in time and the profitability of the company, the tax rates for corporate tax, and the inflation rate. The models have been devised after analyzing methodology issues, related to depreciation policy and investigating current practices in its implementation in specific agricultural companies in present-day Bulgaria. It has been determined that there is a clear-cut relation between the profitability of the companies and the materiality threshold and depreciation method chosen. The main conclusion is that when the companies develop their depreciation policy, at ceteris paribus they should select higher materiality thresholds and diminishing balance depreciation methods due to the inequality of money in time, the acceleration of obsolescence, and the inflation processes.

关键词：折旧方法仿真模型农业企业保加利亚共和国通货膨胀率评估盈利能力