Urganch, Uzbekistan

Urgench State University

Urganch, Uzbekistan
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Eshchanov B.R.,Free University of Brussels | Grinwis Plaat Stultjes M.,Free University of Brussels | Eshchanov R.A.,Urgench State University | Salaev S.K.,Urgench State University
Renewable and Sustainable Energy Reviews | Year: 2013

The energy sectors of fossil fuel-rich Kazakhstan, Turkmenistan and Uzbekistan are heavily dependent on non-renewable resources. The abundance of these resources acts as an obstacle in the process of energy sector diversification in the Central Asian states. The future diversification of energy sources is, however, an inevitable process for many reasons: man-made climate change, the need for transition to reliable and secure energy sources and availability of a vast potential for renewable energy generation being the most important. The current article investigates the decision-makers′ perception on introduction of renewable energy sources in the residential sector of Uzbekistan using a survey-based analysis. The findings indicate that the possibility of becoming independent from the centrally supplied natural gas and electricity grid and availability of state funded financing are the three main drivers of renewable energy penetration while the higher price of energy from the renewable energy sources acts as a major disincentive. It is also revealed that the residents of urban type multi-storey houses have relatively very small opportunities for renewable energy application due to the smaller surface of their rooftops and also due to lack of sufficient surface in the neighborhood. © 2013 Elsevier Ltd.

Cabada A.,University of Santiago de Compostela | Urazboev G.,Urgench State University
Inverse Problems | Year: 2010

In this paper, it is shown that the solutions of the Toda lattice in Flaschka's form with a self-consistent integral-type source can be found by the inverse scattering problem for the discrete Sturm-Liouville operator. Moreover, the conditions are obtained under which the Toda lattice with an integral-type source has pure soliton solutions. The results can be used in modeling special types of electric transmission lines. © 2010 IOP Publishing Ltd.

In this paper the unique solvability of the analog of the Tricomi problem for the third order loaded differential and integro-differential equations with parabolic-hyperbolic operators is proved. The existence of a solution is proved by the reduction to the integral equations with a shift of the second kind. We obtain necessary and sufficient conditions for the existence of a unique solution. © 2014, Baltaeva; licensee Springer.

Pouso O.L.,University of Santiago de Compostela | Jumaniyazov N.,Urgench State University
Journal of Computational and Theoretical Transport | Year: 2016

Several numerical experiments with the steady monoenergetic Fokker-Planck equation in the one-dimensional (1D) slab are performed and discussed. Planar-geometry symmetry is assumed. Results are obtained with a new numerical scheme of order 2 based on finite differences. © 2016 Taylor & Francis Group, LLC.

Abdullaev B.I.,Urgench State University
Journal of Siberian Federal University - Mathematics and Physics | Year: 2014

In this work we study the P-measure and P-capacity in the class of m-wsh functions and prove a number of their properties. © Siberian Federal University. All rights reserved.

Khasanov A.B.,Urgench State University | Yakhshimuratov A.B.,Urgench State University
Theoretical and Mathematical Physics | Year: 2010

We use the inverse spectral problem method to integrate the Korteweg-de Vries equation with a self-consistent source in the class of periodic functions. © 2010 MAIK/Nauka.

Rudenko I.,Urgench State University | Bekchanov M.,Center for Development Research | Djanibekov U.,Center for Development Research | Lamers J.P.A.,Center for Development Research
Global and Planetary Change | Year: 2013

Since independence from the former Soviet Union in 1991, Uzbekistan is challenged to consolidate its efforts and identify and introduce suitable agricultural policies to ease the threat of advancing land, water and ecosystem deterioration. On the one hand, irrigated cotton production provides income, food and energy sources for a large part of the rural households, which accounts for about 70% of the total population. On the other hand, this sector is considered a major driver of the on-going environmental degradation. Due to this dual nature, an integrated approach is needed that allows the analyses of the cotton sector at different stages and, consequently, deriving comprehensive options for action. The findings of the economic based value chain analysis and ecologically-oriented water footprint analysis on regional level were complemented with the findings of an input-output model on national level. This combination gave an added value for better-informed decision-making to reach land, water and ecosystem sustainability, compared to the individual results of each approach. The synergy of approaches pointed at various options for actions, such as to (i) promote the shift of water use from the high water consuming agricultural sector to a less water consuming cotton processing sector, (ii) increase overall water use efficiency by expanding the highly water productive industrial sectors and concurrently decreasing sectors with inefficient water use, and (iii) reduce agricultural water use by improving irrigation and conveyance efficiencies. The findings showed that increasing water use efficiency, manufacturing products with higher value added and raising water users' awareness of the real value of water are essential for providing water security in Uzbekistan. © 2013 Elsevier B.V.

Wei J.D.,TU Braunschweig | Li S.F.,TU Braunschweig | Atamuratov A.,TU Braunschweig | Atamuratov A.,Urgench State University | And 2 more authors.
Applied Physics Letters | Year: 2010

The behavior of GaN surfaces during photoassisted Kelvin probe force microscopy is demonstrated to be strongly dependant on surface polarity. The surface photovoltage of GaN surfaces illuminated with above-band gap light is analyzed as a function of time and light intensity. Distinct differences between Ga-polar and N-polar surfaces could be identified, attributed to photoinduced chemisorption of oxygen during illumination. These differences can be used for a contactless, nondestructive, and easy-performable analysis of the polarity of GaN surfaces. © 2010 American Institute of Physics.

Dubovyk O.,University of Bonn | Menz G.,University of Bonn | Conrad C.,University of Würzburg | Kan E.,Urgench State University | And 2 more authors.
Environmental Monitoring and Assessment | Year: 2013

Advancing land degradation in the irrigated areas of Central Asia hinders sustainable development of this predominantly agricultural region. To support decisions on mitigating cropland degradation, this study combines linear trend analysis and spatial logistic regression modeling to expose a land degradation trend in the Khorezm region, Uzbekistan, and to analyze the causes. Time series of the 250-m MODIS NDVI, summed over the growing seasons of 2000-2010, were used to derive areas with an apparent negative vegetation trend; this was interpreted as an indicator of land degradation. About one third (161,000 ha) of the region's area experienced negative trends of different magnitude. The vegetation decline was particularly evident on the low-fertility lands bordering on the natural sandy desert, suggesting that these areas should be prioritized in mitigation planning. The results of logistic modeling indicate that the spatial pattern of the observed trend is mainly associated with the level of the groundwater table (odds = 330 %), land-use intensity (odds = 103 %), low soil quality (odds = 49 %), slope (odds = 29 %), and salinity of the groundwater (odds = 26 %). Areas, threatened by land degradation, were mapped by fitting the estimated model parameters to available data. The elaborated approach, combining remote-sensing and GIS, can form the basis for developing a common tool for monitoring land degradation trends in irrigated croplands of Central Asia. © 2012 The Author(s).

Kienzler K.M.,International Center for Agricultural Research in the Dry Areas | Lamers J.P.A.,Center for Development Research | McDonald A.,International Center for Maize and Wheat Improvement | Mirzabaev A.,International Center for Agricultural Research in the Dry Areas | And 4 more authors.
Field Crops Research | Year: 2012

Rainfed and irrigated agricultural systems have supported livelihoods in the five Central Asian countries (CAC) for millennia, but concerns for sustainability and efficient use of land and water resources are long-standing. During the last 50 years, resource conserving technologies were introduced in large parts of the rainfed areas while the irrigated areas were expanded largely without considering resource conservation. In more recent years, the use of conservation agriculture (CA) practices has been reported for the different agricultural production (AP) zones in CAC, albeit centering on a single AP zone or on single factors such as crop yield, implements or selected soil properties. Moreover, conflicting information exists regarding whether the current practices that are referred to as 'CA' can indeed be defined as such. Overall information on an application of CA-based crop management in Central Asia is incomplete. This discussion paper evaluates experimental evidence on the performance of CA and other resource conserving technologies in the three main AP zones of CAC, provides an overview of farmer adoption of production practices related to CA, and outlines technical and non-technical challenges and opportunities for the future dissemination of CA practices in each zone. Agronomic (e.g. implements, crop yields, duration, and crop residues), institutional (e.g. land tenure) and economic (e.g. short vs. long-term profitability) perspectives are considered. At present, adoption of CA-based agronomic practices in the rainfed production zone is limited to partial crop residue retention on the soil surface or sporadically zero tillage for one crop out of the rotation, and hence the use of single CA components but not the full set of CA practices. In the irrigated AP zones, CA is not commonly practiced and many of the pre-conditions that typically encourage the rapid spread of CA practices appear to be absent or limiting. Further, our analysis suggests that given the diversity of institutional, socio-economic and agro-ecological contexts, a geographically differentiated approach to CA dissemination is required in the CAC. Immediate priorities should include a shift in research paradigms (e.g. towards more participatory approaches with farmers), development of commercially available reduced and no-till seeders suitable for smaller-scale farm enterprises, and advocacy so that decision makers understand how different policies may encourage or discourage innovations that lead towards more sustainable agricultural intensification in the CAC. © 2011 Elsevier B.V.

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