OALib Journal期刊

ISSN: 2333-9721



匹配条件: “Abdollah Rostamabadi” ,找到相关结果约236条。
Comparison of Plant Diversity and Stand Characteristics in Alnus subcordata C.A.Mey and Taxodium distichum (L.) L.C. Rich
Masoud Tabari,Abdollah Rostamabadi,Ali Salehi
Ecologia Balkanica , 2011,
Abstract: Stand characteristics and understory plant diversity were investigated in low-drained man-made stands of Alnus subcordata C.A.Mey and Taxodium distichum (L) L.C. Rich. The trees were planted with distances of 3 × 3 m and 4 × 4 m in northern Iran. In these stands, herbaceous and woody species were counted in plots of 20 × 20 m. Then, indexes of richness, H/ diversity, J/ equitability and Jaccard similarity (JI), tree growths, cover crown percentage, and litter layer thickness of each stand were assessed following 17 years after planting. The results revealed that the greatest diameter at breast height (D.B.H) and stem height were observed in Alnus 4 × 4 m. By contrast, crown cover percentage and litter thicknesses were greater in Taxodium stands. Species richness, H/ diversity and J/ equitability indexes, Jaccard similarity (JI) of Alnus stands were greater than those of Taxodium stands. In reality, small and light canopy of Alnus is the main reason that the solar radiation can penetrate easily to forest ground and affect understory plant diversity. Alnus as a native tree species, due to greater growth attributes and higher diversity indices in their stands are proposed for plantations in such low-drained sites of northern Iran.
The normal state resistivity of CaTh- and La-doped Y(Nd)-123 superconductors in the bipolaron model
S. Ghorbani,A. Rostamabadi
Iranian Journal of Physics Research , 2007,
Abstract: Polycrystalline samples of Y1-2xCaxThxBa2Cu3O7-δ (with 0.00 ≤x ≤ 0.075) and NdBa2-xLaxCu3O7-δ (with 0.0≤x≤ 0.30) were prepared by the standard solid state method. The transport and superconducting properties have been studied by the resistivity measurements as a function of temperature and doping concentration. Data of resistivity as a function of temperature was analyzed in terms of the bipolaran model. The model well described resistivity data up to near the critical temperature. Obtained results suggested that the hole localization is the main reason for superconducting suppression in the charge neutral doped cuprates and the La doped Nd-123 in addition charge filling.
The Effect of Price Discount on Time-Cost Trade-off Problem Using Genetic Algorithm  [PDF]
Hadi Mokhtari, Abdollah Aghaie
Engineering (ENG) , 2009, DOI: 10.4236/eng.2009.11005
Abstract: Time-cost trade off problem (TCTP), known in the literature as project crashing problem (PCP) and project speeding up problem (PSP) is a part of project management in planning phase. In this problem, determining the optimal levels of activity durations and activity costs which satisfy the project goal(s), leads to a balance between the project completion time and the project total cost. A large amount of literature has studied this problem under various behavior of cost function. But, in all of them, influence of discount has not been in-vestigated. Hence, in this paper, TCTP would be studied considering the influence of discount on the re-source price, using genetic algorithm (GA). The performance of proposed idea has been tested on a medium scale test problem and several computational experiments have been conducted to investigate the appropriate levels of proposed GA considering accuracy and computational time.
General Solution of Generalized (2+1)–Dimensional Kadomtsev-Petviashvili (KP) Equation by Using the –Expansion Method  [PDF]
Abdollah Borhanifar, Reza Abazari
American Journal of Computational Mathematics (AJCM) , 2011, DOI: 10.4236/ajcm.2011.14025
Abstract: In this work, the (G,/G)- --expansion method is proposed for constructing more general exact solutions of the (2 + 1)--dimensional Kadomtsev-Petviashvili (KP) equation and its generalized forms. Our work is motivated by the fact that the (G,/G)---expansion method provides not only more general forms of solutions but also periodic and solitary waves. If we set the parameters in the obtained wider set of solutions as special values, then some previously known solutions can be recovered. The method appears to be easier and faster by means of a symbolic computation system.
General Solution of Two Generalized Form of Burgers Equation by Using the (G'/G)-Expansion Method  [PDF]
Abdollah Borhanifar, Reza Abazari
Applied Mathematics (AM) , 2012, DOI: 10.4236/am.2012.32025
Abstract: In this work, the (G'/G)-expansion method is proposed for constructing more general exact solutions of two general form of Burgers type equation arising in fluid mechanics namely, Burgers-Korteweg-de Vries (Burgers-KdV) and Burger-Fisher equations. Our work is motivated by the fact that the (G'/G)-expansion method provides not only more general forms of solutions but also periodic and solitary waves. If we set the parameters in the obtained wider set of solutions as special values, then some previously known solutions can be recovered. The method appears to be easier and faster by means of a symbolic computation system.
Radioactive Anomalies in 1:50000 Dehbakri Sheet, South of Kerman Province, Iran  [PDF]
Hamid Reza Jafari, Abdollah Yazdi
Open Journal of Geology (OJG) , 2014, DOI: 10.4236/ojg.2014.48031

Using airborne radiometric geophysical data, one can easily investigate a wide region in a short time and with little cost to finally find areas that are rich in radioactive elements. In this research, the uranium exploration data were first organized, filtered and classified and then the frequency distribution tables and histograms were drawn. After drawing the histograms, the statistical parameters for radioactive elements were calculated. The separation of anomaly populations was done on the basis of distribution around mean value, that is, the resulting mean, mean + 1SD, mean + 2SD, and mean + 3SD were assumed to equal to background, threshold value, the possible anomaly and the probable anomaly, respectively. In the end, representative maps of anomalies and separation of anomaly populations from the background were presented based on classical statistical calculations.

Estimation and Comparison of Solar Radiation Intensity by Some Models in a Region of Iran  [PDF]
Abdollah Khalesi Doost, Mozhgan Akhlaghi
Journal of Power and Energy Engineering (JPEE) , 2014, DOI: 10.4236/jpee.2014.24046
Abstract: Due to the increasing explanation of new energy application on a world scale and because of the reduction of environmental pollution arise from usage of solar energy in high potential regions, the necessity of solar radiation measurement in different regions of Iran is obvious. Therefore, in this study, the amount of radiation is measured by Pyranometer from beginning of February to August 2010 in Semnan (The central part of Iran), and it is compared with daily sunny hours, different estimated models of daily radiation such as Angstrom-Pryskat (Montis, Climate classification based on the Terwartha scientific map, using the results of 40 worldwide station, using the results of 9 Synoptic stations in Iran), the Maximum likelihood (using the results of 100 stations in worldwide, using the results of 9 Synoptic station in Iran). Finally, Terwartha scientific map model is proposed because of matching more with measured data on location.
Heat Transfer Analysis in Cooling System of Hydropower’s Generator  [PDF]
Abdollah Khalesi Doost, Reza Majlessi
Open Journal of Applied Sciences (OJAppS) , 2015, DOI: 10.4236/ojapps.2015.53010
Abstract: Cooling process of power plant generator is handled via air-cooled radiators in which the cooling water is supplied from lake with its water temperature varies from season to season. In this study, the effect of temperature fluctuations of cooling water entering the cooling system has been examined via analysis of energy (NTU method) and exergy. The exergy analysis has been done by definition of efficiency coefficient for exergy of cooling media (water) and heating media (air). Besides, the effect of changing the cooling water temperature and flow rate entering the radiators on the cooling system performance has been studied. The results revealed the generator cooling system performance level held sufficient till the temperature of inlet water was kept under 293 k (20°C). On one hand, when the temperature of cooling water at the inlet rises to 12°C, the rate of heat exchange at radiators falls up to 34.3%. On the other hand, by water temperature passing the 12°C limit, the efficiency of cooling media exergy falls to 78% leading to efficiency rise in radiators’ heating media exergy level to 61%. According to the results of this study, changing flow rate of cooling media up to 40% gives rise to the efficiency coefficient of radiators’ cooling media exergy level to about 18.7%. While it does not affect the efficiency level of energy at radiators, the flow rate rise of cooling media may not be considered as a way to give rise to efficiency level of radiators.
The Study of Factors Affecting the Creation of Cognition Based on Power-Knowledge Point of View  [PDF]
Abdollah Rasekhi
Open Journal of Philosophy (OJPP) , 2016, DOI: 10.4236/ojpp.2016.61004
Abstract: Various factors are influencing the creation of cognition so that “Mannheim” refers to economic interests and the insight of groups and social classes, “Weber” to the economic system and the in- terests, and also “Foucault” in his theory of power-knowledge refers to the power. Among the above factors, the power can have the greatest influence on the creation of cognition. So for “Foucault”, the power can lead to the development of knowledge through structures, institutions and discourses. On the other hand, the knowledge as a complement to the power can maintain and expand this latter. But it should be noted that the Knowledge itself can also cause cognition in people by giving them awareness and understanding about things. It seems therefore that cognition is also affected by Power. In this article, we will try to assess a cognition created by the correlations of Power and in the meantime try to learn about other factors that influence the creation of cognition. Hence, this article can help considerably to revise the foundations of Epistemology, as well as to present the specifications of the probable future ideas all in reviewing and reconstructing the sociology routes and appropriate use of present and past experiences and cognitive capacities.
The Impact of Financial Crisis on B2C e-Commerce  [PDF]
Fateme Ghadami, Abdollah Aghaie, Morteza Mohammadkhan
iBusiness (IB) , 2010, DOI: 10.4236/ib.2010.22024
Abstract: Many experts believe that the global financial crisis in 2008 is the worst of its kind since the Great Depression in 1929. The crisis was started from housing market in the US and spread quickly into financial markets. It has had a ripple effect around the world and many other industrialized economies were troubled by its consequences and almost every industry has been influenced by its outcomes. Online retail (or B2C e-Commerce) as a part of retail industry was not immune from the financial crisis and its sales has a dramatic decline. In this paper it is found that 3 factors are main players which have impacted on online retail sales including: less credit available; increasing saving rate and decreasing consumption expenditures and falling consumer confidence and sentiment. Also by representing several figures and tables, factors affecting this trend such as age class, income and gender are discussed.

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