Yerevan, Armenia

Armenian National Agrarian University

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Yerevan, Armenia
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Khachatryan A.K.,Armenian National Agrarian University | Khachatryan K.A.,Armenian National Academy of Sciences
Theoretical and Mathematical Physics(Russian Federation) | Year: 2016

We consider a nonlinear system of integral equations describing the structure of a plane shock wave. Based on physical reasoning, we propose an iterative method for constructing an approximate solution of this system. The problem reduces to studying decoupled scalar nonlinear and linear integral equations for the gas temperature, density, and velocity. We formulate a theorem on the existence of a positive bounded solution of a nonlinear equation of the Uryson type. We also prove theorems on the existence and uniqueness of bounded positive solutions for linear integral equations in the space L1[−r, r] for all finite r < +∞. For a more general nonlinear integral equation, we prove a theorem on the existence of a positive solution and also find a lower bound and an integral upper bound for the constructed solution. © 2016, Pleiades Publishing, Ltd.

Forabosco F.,Armenian National Agrarian University | Forabosco F.,University of Padua | Chitchyan Z.,Armenian National Agrarian University | Mantovani R.,University of Padua
South African Journal of Animal Sciences | Year: 2017

Methane (CH4) and nitrous oxide (N2O) are two important greenhouse gases (GHGs) that are emitted into the atmosphere by livestock during the process of enteric fermentation and manure management. Developing countries produce a large quantity of those emissions, caused mainly by inefficient animal rearing systems, feed production and manure management. This paper outlines the CH4 and N2O emitted from livestock in developing countries and the mitigation actions that could be put in place to reduce atmospheric emissions and increase animal productivity. Emission intensity expresses emission (CO2 equivalents) per unit of product and describes it in relation to the capacity of local animals to produce from local resources. Developing countries are characterized by low production per animal and, consequently, high emission intensity. The emission intensity of dairy cattle in developing countries ranges from 2 to 9 kg CO2-eq/kg fat and protein corrected milk (FPCM) and in only a few cases is below 2 kg CO2-eq/kg FPCM. In sub-Saharan Africa, the average emission intensity is 7.5 kg CO2-eq/kg FPCM for dairy cattle, 71 kg CO2-eq/kg of carcass weight for beef cattle, 6.9 kg CO2-eq/kg FPCM for sheep and goats, and 5 kg CO2-eq/kg eggs for chickens. Taking into account the limited economic and technical resources in most developing countries, the application of appropriate mitigation tools is recommended to reduce the emissions of CH4 and N2O gases in the atmosphere. Increasing livestock productivity through selection and feeding is the most effective tool to reduce emission intensity.

Greta M.,University of Lodz | Lewandowski K.,University of Lodz | Mamikonyan G.,Armenian National Agrarian University
Fibres and Textiles in Eastern Europe | Year: 2017

The Armenian textile and apparel industry has showed very sharp ups and downs throughout its history. During the Soviet era, it was a leading branch of Armenian industry and a major supplier for the whole Soviet Union. Since the early 90s, the situation has dramatically changed. Analysis showed that during the transition from centrally planned to a market-based economy, Armenia’s textile and apparel industry was nearly destroyed. Nowadays the industry, especially the apparel industry, is regarded as one of most promising sectors of the Armenian economy. This potential has also been discovered by Western and Russian institutions and enterprises, which have begun to invest heavily in this sector. © 2017, Institute of Biopolymers and Chemical Fibres. All rights reserved.

Khachatryan A.K.,Armenian National Agrarian University | Khachatryan A.A.,Armenian National Agrarian University
Theoretical and Mathematical Physics(Russian Federation) | Year: 2017

We consider the nonlinear Boltzmann equation in the framework of the Shakhov model for the classical problem of gas flow in a plane layer. The problem reduces to a system of nonlinear integral equations. The nonlinearity of the studied system can be partially simplified by passing to a new argument depending on the solution of the problem itself. We prove the existence theorem for a unique solution of the linear system and the existence theorem for a positive solution of the nonlinear Urysohn equation. We determine the temperature jumps on the lower and upper walls in the linear and nonlinear cases, and it turns out that the difference between them is rather small. © 2017, Pleiades Publishing, Ltd.

PubMed | 11 Health, Armenian National Agrarian University, Rutgers University and Kyorin University
Type: | Journal: Letters in applied microbiology | Year: 2017

Rahmani M.,University of Tehran | Dehghan-Banadaky M.,University of Tehran | Kamalyan R.,Armenian National Agrarian University
Animal Production Science | Year: 2015

Twenty-four early-lactation primiparous and multiparous Holstein cows, beginning 5 weeks postpartum, were used for 4 weeks to investigate the effects of feeding rumen-protected choline (RPC) or vitamin E on milk yield, dry matter intake (DMI), blood metabolites and plasma enzymes. Cows were randomly assigned to one of the following treatments: no supplement (control), 90 g/day of RPC, or 4400 IU/day of vitamin E. Treatments did not affect milk yield, DMI, plasma glucose, non-esterified fatty acids, blood urea nitrogen, aspartate aminotransferase or total bilirubin, whereas feeding RPC affected cholesterol, plasma albumin, and alkaline phosphatase (ALP). Feeding vitamin E affected triglyceride, cholesterol, β-hydroxy butyric acid, gamma-glutamyl transferase and alanine aminotransferase, and highly affected plasma albumin and ALP. There was a tendency for vitamin E supplementation to increase plasma total protein concentration. The results of this study suggest that supplemental vitamin E may improve liver function in dairy cows in early lactation. © 2015 CSIRO.

Gevorgyan A.H.,Armenian National Academy of Sciences | Gevorgyan A.H.,Yerevan State University | Harutyunyan M.Z.,Yerevan State University | Matinyan G.K.,Armenian National Agrarian University | Mkhitaryan S.A.,Yerevan State University
Journal of Physics: Conference Series | Year: 2014

We calculated the photonic density of states (PDS) of the eigen polarizations in the system composed of a stack of layers of a cholesteric liquid crystal and an isotropic medium. The reflection spectra and PDS peculiarities, as well as the peculiarities of absorption and emittance were investigated. We obtained the dependences of the PDS as a function of parameters characterizing absorption and gain. It was shown that the subject system can be used in lasers for obtaining low threshold lasers with the emittance wavelength tunable in wide ranges. The system also can work as a multi-position trigger. © Published under licence by IOP Publishing Ltd.

Harutyunyan M.Z.,Yerevan State University | Gevorgyan A.H.,Yerevan State University | Matinyan G.K.,Armenian National Agrarian University
Optics and Spectroscopy (English translation of Optika i Spektroskopiya) | Year: 2013

Optical properties of a stack consisting of layers of a cholesteric liquid crystal (CLC) and an iso-tropic medium are investigated. The problem is solved using the modified Ambartsumyan layer-summation method. Particular features of reflectance spectra of this system are studied. It is shown that, in contrast to a single CLC layer, this system exhibits multiple photonic band gaps. There are two types of photonic band gaps: selective and nonselective with respect to polarization of the incident light. It is shown that eigenpolarizations in the system generally coincide with quasi-orthogonal quasi-circular polarizations, except for regions that are selective with respect to polarization of the diffractive reflection. It is shown that, for an even number of layers, the system under consideration is nonreciprocal and can function as an optical diode. The influence of thickness of CLC sublayers, angle of incidence, local dielectric anisotropy of CLC layers, refractive indices and thicknesses of layers of an isotropic media on reflectance spectra and other optical characteristics of the system is investigated. © Pleiades Publishing, Ltd., 2013.

Yezekyan T.,Armenian National Agrarian University | Olt J.,Estonian University of Life Sciences
Engineering for Rural Development | Year: 2016

Vineyard floor management is a mandatory agricultural method for cultivating this kind of crop. In order to develop a strong root system and the portion of the plant that is above the ground, the soil must contain not only the required nutrients, but it should also be sufficiently humid, well-aerated, and have good thermal conductivity. The soil must be free from weeds that compete with grapevines for nutrients and moisture and aggravate the thermal conditions of the soil by shading it. The means for weed control depend on the soil and weather conditions, the thickness of weed vegetation, the irrigation system, and whether there is an underlying principle of using chemical agents for fighting weeds. In this article we considered widespread methods and techniques for weed control, improving the structure of soil and the methods of cultivating the areas between the plants in the vineyards, the comparison and justification of such methods from the financial perspective, and also the provision of necessary agrotechnical parameters of cultivating this kind of crop. The conducted comparative analysis has shown that the climate, anatomic and physiological peculiarities of grape varieties cultivated in Armenia are an important aspect that is being taken into consideration in developed countries upon choosing the machines for cultivating the areas between the plants in the vineyards. The purpose of this article is to develop to the vertical inter-row tiller of vineyards developed at the Armenian National Agrarian University (ANAU) an alternative variant for rocky soils and without power drive, or, in other words, with the principle of free-active spin-harrow for the inter-tillage of plant rows.

Avetisyan S.,Armenian National Agrarian University | Avetisyan A.,Armenian National Agrarian University
Acta Horticulturae | Year: 2014

The article touches upon the development trends of vegetable growing during the last two decades in RA and shows that vegetable growing is one of the most important and intensively developing branches of agriculture. Vegetable crops used to make 4% of the total crops on the eve of agrarian reforms (1990), whereas the rate was 8.7% in 2011. In the same period production volume doubled, increasing from 389.7 to 789.3 thousand tons. By the way, production growth owes mostly to intensive factors, as crop yield has increased by 46%. Nevertheless, our studies show, that the production development potential of the Republic's vegetable growing sector is not fully utilized. The sector has a number of main issues and upon solving those issues vegetable growing will become one of the most profitable agricultural sectors and will contribute to the income increase of the farmers and the reduction of poverty. In particular, the following issues have been discussed: - Promotion of innovation development in the field of vegetable growing, namely, improvement of selection and seed breeding using modern technologies, upgrade of sorts and cultivars in line with the market demand; - Targeted state support for the establishment of marketing logistic support for fresh and processed vegetable products; - Improvement of vegetable growing system and the increase in the share of plants ensuring high added value; - Optimal distribution of vegetable growing in marzes and adoption of beneficial organizational-economic conditions for diversification; - Development of legal-contractual system for long-term cooperation among vegetable growing farmers, processing and exporting companies. - The solution of the stated, though not all the existing issues will be an incentive for the efficient development of the fields of vegetable growing and food processing.