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匹配条件: “Yanitsa Petrova” ,找到相关结果约229条。
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Influence of Vegetation on the Avifauna in Two Urban Parks in Plovdiv, Bulgaria
Yanitsa Petrova,Atanas Irikov
Ecologia Balkanica , 2012,
Abstract: This study is related to the investigation of the impact that vegetation caused on the avifauna of the parks “Lauta” and “Tsar Simeon Garden” located in the city of Plovdiv, Bulgaria. As a result of the study, we found that the biodiversity of the vegetation in park “Tsar Simeon Garden” is highly significant in comparison with the same in park “Lauta”. In the park “Tsar Simeon Garden” introduced plant species dominate over indigenous species, as compared with the park “Lauta”. The differences in the vegetation are caused by different management approaches carried out in the both parks. The degree of similarity between trees and bushes in both parks is low. The vegetation also had a significant influence on the avifauna living within the parks. The avian biodiversity in park “Lauta” is two times higher in comparison with the avian biodiversity in park “Tsar Simeon Garden”. The degree of similarity in the avifauna between both parks is significant, due the fact that all of the species, except one documented in “Tsar Simeon Garden” being documented in park “Lauta” as well. Eighteen new species of birds were recorded and described for the first time in the city of Plovdiv. The conservation status of the avifauna in park “Lauta” is quite significant in comparison with the same in park “Tsar Simeon Garden”.
Revisiting the Effects of Economic Incentives on Motivation  [PDF]
Kameliia Petrova
Theoretical Economics Letters (TEL) , 2012, DOI: 10.4236/tel.2012.22041
Abstract: This paper presents a formal framework for modeling the effects of economic incentives on motivation. While economic models represent the utilities from monetary incentives and private benefits in an additive form, studies in psychology show that extrinsic and intrinsic motivation are non-additive and that there exists a continuum between the two. To accommodate for possible interaction effects, a non-additive probability model and evidence theory have been used in the principal-agent set-up. The model produces results consistent with prior evidence presented in social psychology studies.
Some Remarks to Numerical Solutions of the Equations of Mathematical Physics  [PDF]
Ludmila Petrova
American Journal of Computational Mathematics (AJCM) , 2013, DOI: 10.4236/ajcm.2013.33029
Abstract:

The equations of mathematical physics, which describe some actual processes, are defined on manifolds (tangent, a companying or others) that are not integrable. The derivatives on such manifolds turn out to be inconsistent, i.e. they don’t form a differential. Therefore, the solutions to equations obtained in numerical modelling the derivatives on such manifolds are not functions. They will depend on the commutator made up by noncommutative mixed derivatives, and this fact relates to inconsistence of derivatives. (As it will be shown, such solutions have a physical meaning). The exact solutions (functions) to the equations of mathematical physics are obtained only in the case when the integrable structures are realized. So called generalized solutions are solutions on integrable structures. They are functions (depend only on variables) but are defined only on integrable structure, and, hence, the derivatives of functions or the functions themselves have discontinuities in the direction normal to integrable structure. In numerical simulation of the derivatives of differential equations, one cannot obtain such generalized solutions by continuous way, since this is connected with going from initial nonintegrable manifold to integrable structures. In numerical solving the equations of mathematical physics, it is possible to obtain exact solutions to differential equations only with the help of additional methods. The analysis of the solutions to differential equations with the help of skew-symmetric forms [1,2] can give certain recommendations for numerical solving the differential equations.

The Peculiarity of Numerical Solving the Euler and Navier-Stokes Equations  [PDF]
Ludmila Petrova
American Journal of Computational Mathematics (AJCM) , 2014, DOI: 10.4236/ajcm.2014.44026
Abstract: The analysis of integrability of the Euler and Navier-Stokes equations shows that these equations have the solutions of two types: 1) solutions that are defined on the tangent nonintegrable manifold and 2) solutions that are defined on integrable structures (that are realized discretely under the conditions related to some degrees of freedom). Since such solutions are defined on different spatial objects, they cannot be obtained by a continuous numerical simulation of derivatives. To obtain a complete solution of the Euler and Navier-Stokes equations by numerical simulation, it is necessary to use two different frames of reference.
How Did the Yakuts Fortify Themselves against the Cold?  [PDF]
Svetlana Ivanovna Petrova
Open Journal of Social Sciences (JSS) , 2015, DOI: 10.4236/jss.2015.33017
Abstract: This article is dedicated to the analysis of the heat-insulating function of winter clothes and personal cold-protective equipments (protectors), which grew out of use at the beginning of the XX century and now are kept in different museum funds. The author pays the main attention to the description of the material, production technologies, and functional heat-insulating properties of the traditional winter clothes and protectors. The article also discusses ethnocultural parallels of the traditional clothes.
Natural hazards and technological risk in Russia: the relation assessment
E. Petrova
Natural Hazards and Earth System Sciences (NHESS) & Discussions (NHESSD) , 2005,
Abstract: Almost every natural disaster is accompanied by some sort of technological one. A number of studies also show a correlation between technological disasters and various global processes such as solar disturbances, geophysical field variation etc. In this study we attempted to ascertain and codify the relationship between different types of technological disasters and natural hazards. Two types of natural hazards were found, based on their genesis, distribution in time, and impact pattern on the technosphere. Solar and geomagnetic disturbances generally affect technological risk through the failure of automatic machinery and the reduction of operator reliability. They increase the probability of transport accidents, fires, and catastrophic toxic emissions. These types of technological disasters are widely prevalent throughout Russia and in all federal regions. Geological, climatic, hydrological, and other natural hazardous processes increase technological risk through direct mechanical impacts. Their occurrence in space and time depends on the character of the natural process and the specific regional environment. The total number and proportion of technological disasters in federal regions results mainly from the concentration of industrial units and their type, as well as the local natural and social environment. Temporal changes in the number of technological disasters of different groups depend on the prevailing type of natural processes.
Modeling word order variation in discourse: On the pragmatic properties of VS order in Old High German VS order in Old High German
Svetlana Petrova
Oslo Studies in Language , 2011,
Abstract: In Old High German, verb-initial matrix declarative clauses display a variety of functions which are broadly related to discourse structure. However, the tho-V2 construction also correlates with the factors triggering verb-initial placement. The paper shows that the preference of the one pattern over the other cannot be explained in terms of a single, straightforward criterion. Rather, several factors influencing the choice process are recognized in the literature. The paper tests the effect of these factors by using methods and tools developed to capture variability in sociolinguistics.
Vulnerability of Russian regions to natural risk: experience of quantitative assessment
E. Petrova
Natural Hazards and Earth System Sciences (NHESS) & Discussions (NHESSD) , 2006,
Abstract: One of the important tracks leading to natural risk prevention, disaster mitigation or the reduction of losses due to natural hazards is the vulnerability assessment of an 'at-risk' region. The majority of researchers propose to assess vulnerability according to an expert evaluation of several qualitative characteristics, scoring each of them usually using three ratings: low, average, and high. Unlike these investigations, we attempted a quantitative vulnerability assessment using multidimensional statistical methods. Cluster analysis for all 89 Russian regions revealed five different types of region, which are characterized with a single (rarely two) prevailing factor causing increase of vulnerability. These factors are: the sensitivity of the technosphere to unfavorable influences; a 'human factor'; a high volume of stored toxic waste that increases possibility of NDs with serious consequences; the low per capita GRP, which determine reduced prevention and protection costs; the heightened liability of regions to natural disasters that can be complicated due to unfavorable social processes. The proposed methods permitted us to find differences in prevailing risk factor (vulnerability factor) for the region types that helps to show in which direction risk management should focus on.
Social and economic factors of the natural risk increasing: estimation of the Russian regions
E. Petrova
Natural Hazards and Earth System Sciences (NHESS) & Discussions (NHESSD) , 2004,
Abstract: This study is an attempt to assess quantitatively social and economic factors that determine vulnerability of Russian regions to natural risk, to trace the space differences of the considered factors, and to group the regions by their similarity. In order to indicate the regional differences in social and economic development, equipment condition, dangerous substances accumulation, and social trouble four the most suitable parameters were estimated, including the per capita production of Gross Regional Product (GRP), capital consumption, volume of total toxic waste, and crime rate. Increase of the first parameter causes vulnerability reducing, the increase of the last three causes its increasing. Using multidimensional cluster analysis five types of regions were found for Russia according to similarity of the considered parameters. These types are characterized with higher value of a single (rarely two) chosen parameter, which seems to be sufficient enough to affect natural risks increasing in these regions in near future. Only few regions belonging to the fifth type proved to have rather high value of GRP and relatively low values of the other parameters. The negative correlation was found between a number of natural disasters (ND) and the per capita GRP in case when some parameters reached anomalously high value. The distinctions between regions by prevailing different parameters, which result in natural risk increasing, help risk management to find directions where to focus on.
Inflation Targeting in Practice: A Survey
Kameliia Petrova
International Journal of Business and Management , 2012, DOI: 10.5539/ijbm.v7n6p58
Abstract: Since its first introduction in New Zealand in 1990, inflation targeting has been successfully adopted in several industrialized countries-Canada, the United Kingdom, Sweden, Finland, Australia in the early 1990s; and Iceland and Norway a decade later. More recently, several emerging market economies (Mexico, Israel, Chile, and Brazil among them) have tried to move in the same direction. I have performed a cross-country comparison of the application of inflation targeting framework. Reviewing case studies and empirical evidence from the past twenty years, I present and summarize the most recent results and practical issues experienced by the emerging market economies, as well as the necessary steps that should be considered to ensure a successful implementation.
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