Showing 6 results for Keshavarz
T. Honar, M. Javan, A. Keshavarzi,
Volume 6, Issue 3 (fall 2002)
Abstract
Side weirs as flow diversion devices are widely used in irrigation, land drainage and urban sewage systems. In the present study, the effects of the length and height of inclined side weir crest on discharge coefficient were investigated in prismatic and nonprismatic rectangular channels.. In this study, 675 laboratory tests were conducted.
Analysis of experimental tests showed that the discharge coefficient is strongly correlated with uptream Froude number, height of weir to depth ratio at upstream of weir, ratio of water depth on weir to length of weir, and with prismatic factor. Based on experimental results, a model is proposed. The model is capable of estimating the discharge coefficient under subcritical flow conditions. Finally, the data from the proposed model was compared with those obtained by other researchers under different side and bed slopes. There was a good agreement with a relative error of less than ten percent.
S. M. Taghavi, K. Keshavarz,
Volume 6, Issue 4 (winter 2003)
Abstract
During the period from 1997 to 1998, samples of wheat leaves were collected from different wheat farms in Fars and Kohgiluyeh & Boyrahmad provinces to identify the causal agent of wheat leaf blight. On the basis of LOPAT tests and production of fluorescent pigment on KB medium, 181 bacterial isolates were recovered from the samples. Based on biochemical, physiological and pathogenicity tests, the isolates were categorized in five groups. One group was found to be Pseudomonas fluorescens (Pf) and the remaining groups were identified as P. syringae pv. syringae (Pss). The pathogenicity test indicated that Pss strains were the causal agent of bacterial wheat leaf blight in Fars and Kohgiluyeh & Boyrahmad provinces. Whole protein electrophoretic patterns were similar in Pss isolates but only a few showed small variation in some subordinated bands. Pathogenic strains of Pss were also isolated from annual and perennial weeds such as foxtail, hairy vetch, oat grass, barley grass and Cynodon dactylon in some areas including Saadat Shahr and Marvdasht. Among the wheat cultivars tested, Tajan was susceptible to the pathogen but others were immune, resistant, moderately resistant, or moderately susceptible. The results showed that Pss is a seed-born pathogen in wheat kernel perhaps as endophyte in the seeds.
A. Keshavarzi, M. J. Kazemzadeh Parsi,
Volume 10, Issue 1 (spring 2006)
Abstract
Flow structure at water intake is very complicated and three-dimensional. Due to this the application of one and two-dimensional equations can not sufficiently explain the flow structure at water intake. In this study, the simulation of flow structure at a 45 degree water intake was investigated numerically and experimentally. Here, the characteristic of separation zone and velocity distribution at 45 degree water intake were investigated using Standard k-ε and RNG k-ε models. It was found that the Standard k-ε model enables to estimate the flow and separation zone at water intake. Also, the location of separate zone at the inlet of water intake was studied using experimental and numerical approach. It was found that the separation zone at 45 degree water intake occurs at the downstream of the inlet.
A. Dehghani, A. Fotovat, Gh. Haghnia, P. Keshavarz,
Volume 11, Issue 41 (fall 2007)
Abstract
M. Keshavarz , E. Karami ,
Volume 12, Issue 43 (spring 2008)
Abstract
Drought is an unavoidable natural disaster in dry and arid regions of the world. Studies indicate that Iran with its geographical and climatic characteristics is poor in water resources. Moreover, it is estimated that in 2025, Iran should increase the water resources by 112% in order to maintain status quo. Therefore, the occurrence of drought is more prevalent in the future. This implies a real challenge for researchers to study how to manage farms during the onset of drought. Inappropriate management strategies result in loss of resources, which in turn leads to more destructive impacts of drought, consequently leading to more droughts in future. The purpose of this survey study was to identify factors influencing drought management among farmers in Fars province, Iran. A multistage stratified random sampling technique was used to select a representative sample of farmers who has experienced drought in recent years. A total of 258 farmers were interviewed using a questionnaire. A panel of experts verified face validity. A pilot study was used to assess the reliability of the measuring instrument. Cluster analysis and Structural Equation Modeling were used for data analysis. Results indicated that farmers with different social, economical, and technical characteristics chose different management strategies when coping with drought conditions. Despite farmers' efforts to manage drought, they face harsh consequences. These consequences include economic losses and degradation of farming environment. It is therefore recommended that policy makers who are involved in drought management programs learn more about farmers' drought mitigation techniques and make further attempts to increase the efficiency and effectiveness of techniques used by farmers.
Z. Maghsodi, M. Rostaminia, M. Faramarzi, A Keshavarzi, A. Rahmani, S. R. Mousavi,
Volume 24, Issue 2 (Summer 2020)
Abstract
Digital soil mapping plays an important role in upgrading the knowledge of soil survey in line with the advances in the spatial data of infrastructure development. The main aim of this study was to provide a digital map of the soil family classes using the random forest (RF) models and boosting regression tree (BRT) in a semi-arid region of Ilam province. Environmental covariates were extracted from a digital elevation model with 30 m spatial resolution, using the SAGAGIS7.3 software. In this study area, 46 soil profiles were dug and sampled; after physico-chemical analysis, the soils were classified based on key to soil taxonomy (2014). In the studied area, three orders were recognized: Mollisols, Inceptisols, and Entisols. Based on the results of the environmental covariate data mining with variance inflation factor (VIF), some parameters including DEM, standard height and terrain ruggedness index were the most important variables. The best spatial prediction of soil classes belonged to Fine, carbonatic, thermic, Typic Haploxerolls. Also, the results showed that RF and BRT models had an overall accuracy and of 0.80, 0.64 and Kappa index 0.70, 0.55, respectively. Therefore, the RF method could serve as a reliable and accurate method to provide a reasonable prediction with a low sampling density.
