Showing 6 results for Asgari
M. Shafai Bajestan, M. Ostad Asgari,
Volume 4, Issue 2 (summer 2000)
Abstract
The application of “Modified Einstein Procedure” is recommended by the Specialized Committee on Sediment, Iranian Ministry of Energy. However, this method has not been applied to any river in the country. It is the purpose of this study to investigate the total sediment load of the Karun and Karkheh rivers at Ahwas and Hamidieh stations.
The graphical calculations of the method are very complicated and time consuming. Therefore, a mathematical model has been developed in this study to improve the accuracy, simplicity and speed of computations. The required data were obtained from the above stations for seven years (1988-95), and applying these data, the total sediment load was calculated using the model. The bed load for the above stations was also computed and the ratio of bed load to total sediment load was calculated. In addition, measured data from East Fork river (in USA) were applied to examine the accuracy of the method in estimating the bed load. Comparison of the measured and computed results shows that the “Modified Einstein Procedure” estimates the amount of bed load with a high accuracy. The relationship between the bed load and suspended load and also between the total load and the stream discharge have also been established.
Finally, it is concluded that the “Modified Einstein Procedure” with minor modifications can be successfully applied for the above-mentioned rivers of Karun and Karkheh.
Y. Fathipour, A. Hosseini, A. A. Talebi, S. Moharramipour, Sh. Asgari,
Volume 9, Issue 2 (summer 2005)
Abstract
The biological parameters of cabbage aphid, Brevicoryne brassicae (L.) was studied in the laboratory conditions under the three constant temperatures (20, 25 and 30 ºC), RH 60±5% and a photoperiod of 16:8 (L:D) using 40 first instar nymphs. Among nymphs, 40%, 55% and 10% of them completed their nymphal period in 20, 25 and 30 ºC, respectively and developed to adult stage. In 30 ºC, the most biological acitivities of aphid were disrupted and the most individuals (nymphs and adults) were killed. Most developmental periods, longevity and the amount of reproduction in 20 ºC were significantly greater than other temperatures. In temperatures 20, 25 and 30 ºC the last individual of a cohort died in age of 33, 29 and 16 days, respectively. The life expectancy of cabbage aphid in the first day of experiment was 13.93, 10.50 and 7.19, respectively according to the mentioned temperatures. There was a little difference between net reproduction rates in temperatures 20 and 25 ºC (16.74 and 15.92, respectively). Net reproduction rate was reduced extremely in temperature 30 ºC (1.75). The intrinsic rate of the increase in the temperatures 20, 25 and 30 ºC were 0.187, 0.226 and 0.042, respectively. The results indicated that 25 ºC was the optimal temperature for biological activities of B. brassicae and its highest population growth was observed at this temperature.
M. Haghighat Afshar, M. Babalar, A. Kashi, A. Ebadi, M. A. Asgari,
Volume 10, Issue 3 (fall 2006)
Abstract
Some strawberriy cultivars (Fragaria x ananassa Dutch. cv. Aliso, Selva, Gaviota and Camarosa) were grown hydroponically with five NH4:NO3 mM concentration ratios (0/6 (S1), 0.25/6 (S2), 0.5/6 (S3), 1/6 (S4), 2/6 (S5) and constant nitrate concentration in three replicates for two seasons: Summer and Winter, in greenhouses of Agriculture Faculty of Tehran University. The results are reported as Follows: In summer shoot dry weight and shoot/ root ratio were highest in 0.25 and 0.5 mM NH4-N and were constant in remaining solutions with higher ammonium concentration. Increasing ammonium concentration resulted in decreasing the root dry weight. Aliso and Selva had the highest shoot and root dry matter respectively. Gaviota had the highest runner. In winter, shoot dry matter was highest in plants grown in S5 solution. Increasing ammonium from 0 to 0.5 mM decreased fruit yield but more ammonium in S4 and S5 solution increased yield. Root and fruit dry matter were highest in Selva. Yield and Fruit fresh weight were highest in Gaviota. Camarosa had the highest shoot dry weight. In summer shoot dry weight was significantly higher than in winter. Due to the high yeild, commercial use of the S5 solution and the cv. Gaviota is recommended.
K. Asgari, S. H. Tabatabaei, P. Najafi, Sh. Kiani,
Volume 20, Issue 78 (Winter 2017)
Abstract
Constant use of treated wastewater (TWW) for irrigation over long periods may cause buildup of heavy metals up to toxic levels for plants, animals, and entails environmental hazards in different aspects. The aim of this study was to assess the effect of using a deep emitter installation on lowering the potential heavy metal accumulation in soil and wheat grain, and health risk under drip irrigation with treated municipal wastewater. A field experiment was conducted according to a split block design with two treatments (fresh and wastewater) and three sub treatments (0, 15 and 30 cm depth of emitters) in four replicates in Esfahan, Iran. Soil samples were collected before planting (initial value) and after harvesting (final value) in each year. Elemental concentrations (Cu, Zn, Cd, Pb, Cr, and Ni) in soil and grain were determined using an atomic absorption spectrophotometer. A pollution load index (PLI) showed that there was not substantial buildup of heavy metals in the wastewater-irrigated soils compared to the freshwater-irrigated soils. Cu, Pb, Cr and Zn concentrations in wheat grain were within permissible EPA limits, but concentrations of Cr was above the safe limits of EPA. In addition, concentrations of Ni in wheat grain were several folds higher than EPA standards. A health risk index (HRI) which is usually adopted to assess the health risk to hazard materials in foods showed values higher than 1 for Cd and Cu, whereas children might also be exposed to health risk of Cd, Cu and Cr. Based on aforementioned results, it can be concluded that the depth of emitter in drip irrigation does not play a significant role in the accumulation of heavy metals from TWW in our sandy loam soil.
A. Darzi-Naftchali, S. Rafierad, M. Khoshravesh, A. Asgari, M. R. Babaei, H. Zabardast-Rostami,
Volume 23, Issue 1 (Spring 2019)
Abstract
Water is a vital source for both human and biological living. Today, water management and conservation, not only both in developing countries but also in and the developed countries ones, has is of great importance. In the traditional economy, water is not considered as a productive factor in the national accounts; however, but in reality, water is the primary factor in many direct and indirect goods and services. To evaluate the effect of growth in the added value of agriculture, industry and electricity sectors on the added value of water sector in the Mazandaran province, coefficients of ARDL model were estimated using the Micro fit software. The extended Dickey-Fuller unit root test was used for the statistical test of variables. The static test of variables showed that all variables were significant at the 95% confidence level and were also consistent with the theory. A 1% increase (decrease) in the added value of industry and electricity resulted in the increase of 0.54 % and 0.39 %, respectively, increase (decrease) in the added value of the water sector, respectively. Also, 1% increase (decrease) in the added value of the agricultural sector caused in a 0.54% increase (decrease) in the added value of the water sector. Industry and electricity sectors affected the added value of water sector more than agriculture. In the long-term, the growth of the added value of the industry sector had the greatest impact on the growth of the added value of water sector. Based on the results, controlling water use in agriculture, industry and electricity sectors increases increased the effects of the added value of these sectors on the added value of the water sector.
R. Hosseinpour, H.r. Asgari, H. Nikanhad Qermakher, E. Malekzadeh, M.k. Kianian,
Volume 27, Issue 4 (Winter 2023)
Abstract
The soils of desert areas are mostly low in organic matter and may fluctuate greatly in terms of acidity. Biochars are one of the materials used to improve and modify some soil characteristics. This compound is very resistant to decomposition and remains in the soil for a longer period, reducing agricultural waste and turning it into a soil conditioner. This leads to keeping carbon in the soil, increasing food security, increasing biodiversity, and reducing deforestation. In this research, an attempt was made to investigate the biochar of fodder beet plant waste produced at different pyrolysis temperatures and its physical and chemical characteristics. For this purpose, fodder beet wastes were collected from settlements around Birjand and after being crushed and air-dried, they were pyrolyzed in an electric furnace under limited oxygen conditions at a temperature range of 300-700 degrees Celsius. Then, the characteristics of the produced biochars were performed with 3 repetitions of measurements and statistical analyses with SPSS software. The results of this research showed that the characteristics of biochars changed significantly with temperature change. The highest yield percentage (59%), organic carbon (56.33%), total nitrogen (0.53%), water retention (0.84g/g) at 300 and 400 degrees Celsius, and the highest amount of ash (% 76), acidity (8.21) and electrical conductivity (0.1ds/cm) was obtained at a temperature of 700 degrees Celsius. The percentage of carbon and the efficiency of biochar produced at temperatures of 300 and 400 degrees Celsius were higher than other biochar produced at other temperatures. Biochar produced at 300°C has better characteristics in terms of carbon percentage and acidity efficiency compared to biochar produced at 400°C. Although these differences were not statistically significant, due to biochar production being more economical in terms of energy consumption, it is recommended to produce biochar at a temperature of 300 degrees Celsius.
