Showing 8 results for Demand
G.a. G. A. Sharzei, M.a. M. A. Ghetmiri, M. M. Rastifard,
Volume 6, Issue 1 (4-2002)
Abstract
This paper studies the structure of cost and production of rice using cross section data from rice farming in Guilan in 1997. A translog cost function is specified for this purpose and estimated, using Iterative Seemingly Unrelated Regressions for both the short and the long run where all factors are taken to be variables. The results of the study are as follows:
1. Neither in the short-run nor in the long-run is the possibility of technical substitution among the factors of production strong.
2. Own and cross price elasticity of demand for inputs are positive but less than one, hence limited substitutability among inputs is possible as the result of a change in input prices.
3. As the structure of production of rice in Guilan exhibits increasing returns to scale, increased allocation of land to the production of rice could result in a lower price of the product.
4. Inputs are not homogeneous, therefore, not all producers are faced with the same price for the same input. Nevertheless, the cost of production has been lower for those farmers who have paid a higher price for an input. Therefore, the higher price for inputs is more than that compensated by the quality of each input in the production process.
5. Due to the inelasticity of the demand for rice with respect to prices, a large price increase is required to stimulate farmers to allocate more resources to the production of rice.
6. Since the possibility of substitution among inputs is limited, a large increase in relative prices is required in order to change the structure of rice production.
J. Torkmani, Sh. Shajari,
Volume 12, Issue 44 (7-2008)
Abstract
The main objective of this paper is to study the differential impacts of various irrigation water pricing policies. The methodology used is based upon Multi-Attribute Utility Theory (MAUT) mathematical programming models and also simulation. Two kinds of data needed to feed the models were obtained from official records and surveying. The analysis of water pricing policy indicates that the most important relative savings take place in the more conservative farmers due to their risk-aversion behavior. Also it can be seen that in the elastic segments of the demand curves the increase in the price of water encourages great saving in consumption due to changes in mixed crops, crops production by deficit irrigation methods and production of rain-fed crops. Results clearly demonstrate that each homogenous group of farmers displays different behavior patterns related to this natural resource. Therefore, this shows the usefulness of differential analysis in evaluating the impact of water pricing policy.
M Zibaei, R Rahmani,
Volume 13, Issue 48 (7-2009)
Abstract
In this study the causality relationship among variables in chicken and beef markets were investigated based on annual data from 1974 to 2004 in the I.S. of Iran. For this purpose, causality algorithms emerging from directed acyclic graphs were used in two cases, one based on co- integration analysis and innovation correlation matrix of Vector Error Correction Model (VECM) and the other using data directly. In the investigation of causality process, PC algorithm based on partial correlations and GES (Greedy Equivalent Search) based on Bayesian network model were used. The results revealed that there is no specific causality relation between chicken and beef consumption and their price indices. Thus it seems other variables and government interventions are effective factors in these markets. Therefore, this model is an instrument for forecasting changes of these variables. In these markets there are causality relations among price indices, quantities of consumption and other variables. Beef price index as endogenous variable, is under the effect of chicken price index, non meat food price index, non food price index, per capita expenditure and quantity of chicken consumption. The quantity of beef consumption is predetermined and isn’t under the effect of other variables. Chicken price index is endogenous and under the effect of beef price index, per capita expenditure and non food price index. Also chicken quantity consumption is endogenous and under the effect of beef quantity consumption and non meat food price index. With respect to the findings, for effectiveness, policy initiatives aimed at improving in meat industry should be different for different meat markets and the method of directed graphs can be used a s a guideline.
J Torkamani, H Dehghanpor,
Volume 13, Issue 48 (7-2009)
Abstract
The objective of this study was to investigate the demand of food and nonfood commodities among urban and rural households. To this aim, an appropriate functional form and approximation index were established. Then, Deaton and Mulbaer Iterative (DMI) approach as a linear approximation of Almost Ideal Demand System was used. The study horizon was also 1362-1383(1983-2004). The findings revealed that for urban households housing, fuel, power and furniture, household operations and entertainment, education and food, beverages, tobacco are considered necessary. While clothing, footwear and medical care and transport, communication and other goods are consumed as superior commodities. For urban households, a weak complementary and substitution relation among selected commodities was recognized. In the case of rural households clothing, footwear and food, beverages, tobacco were revealed to be necessary, while housing, fuel, power and medical care and entertainment, education were found superior. For the rural households only furniture and house operation was found elastic. The compensated and uncompensated self price elasticizes were similar regarding the sign and magnitude coefficients for rural and urban households.
M. H. Zibaei, A. M. Akhoond-Ali,
Volume 20, Issue 78 (1-2017)
Abstract
Water scarcity is a major and structural problem in arid and semi-arid regions across the world that greatly concerns environmental policy-makers. The problem of adjusting the demand exceeding the sustainable supply has been mainly tackled with demand policies, particularly through investment in water saving technology and promotion of irrigation efficiency programs. However, there have been very few evaluations of these programs and many of those that exist raise serious doubt about the programs’ effectiveness in reducing the consumptive use of water, due to the occurrence of the rebound effect. In this study, a sample of 243 farmers in Fars province who have the sprinkler irrigation system installed in their farms was interviewed to collect needed data for investigating the rebound effect using AHP and ordered logit regression model. The results indicated that 74.5 percent of sampled farmers have experienced medium to large rebound effect. It was also found that the amount of dry and fallow land during installation of sprinkler irrigation system have a positive relationship with the probability of occurrence of the rebound effect. Finally, the results of this study can be used to determine the probability of the rebound effect occurrence after installment of the sprinkler system for farms where data is available. For example, in the farms with farm features 24, probability of the rebound effect as a result of water saving measures at the low, medium and high levels are 0.4, 32 and 67.4 percent, respectively. Therefore, we must apply specific water conservation and efficiency practices in such farms based on a combined use of technical, economic, social and political tools to reduce pressure on scarce water supplies.
H. Hasheminejada, M. Sayedbarzin, K. Jeirany, A. Taebi,
Volume 23, Issue 1 (6-2019)
Abstract
Detergents are the main organic pollutants in the industrial and domestic wastewater. Electro-chemistry methods are advanced purification methods developed with high efficiency features. The goal of this study was to investigate the possibility of using electrocoagulation and the complementary flocculation process to achieve the highest removal efficiency of the detergent COD. So, with iron electrode, synthetic samples at the concentrations of 500, 750 and 1000 mg/l (with COD of 217, 268 and 370 mg/l, respectively) and with the initial pH levels of 5, 7.3 and 9 were tested. Variable parameters during the electrocoagulation process included the current duration at 3, 5 and 10 minutes, and the current density was at 4, 10, 16 and 22 mA/cm2. The primary results showed that in the optimum conditions, the coagulation process and complementary flocculation could reduce the sample’s COD with an initial concentration of detergent (500 mg/l) from 217 mgO2/l to 81.30 mgO2/l. The electrocoagulation method could reduce the chemical oxygen demand to below the standard limit of environmental discharge (200 mgO2/l) and compensate for the possibility of the irrigation of green spaces due to water shortages.
O. Mohamadi, M. Heidarpour, S. Jamali,
Volume 23, Issue 3 (12-2019)
Abstract
Shortage of water resources and renewable per capita in last 30 years is put Iran on crisis threshold. Wastewater reuse is one of the battle solutions for water shortage and prevents wastewater depletion and environmental pollution. Thus, a pilot scale experiment was carried out to evaluate an integrated anaerobic/aerobic treatment for removal of BOD5 and COD, also to reduction of hydraulic retention time by considering optimum removal efficiency. The pilot was an anaerobic/aerobic bioreactor type under continuous-feeding regime based on a central composite design. The pilot was studied in different retention time and aeration was carried out between 5-15 hours. According to different retention times for COD removal efficiency, 24 hours was selected as optimum hydraulic retention time, that it is comparable to those obtained for 48 hours and over in plant roughly and could remove COD and BOD in acceptable ranges, results showed that average removal efficiency for BOD5 were 63.86 and 83.99 percent in aerobic and anaerobic phases, respectively. The average removal efficiency for COD was 76.5 and 74.35 percent for anaerobic and aerobic sections, respectively. The average removal efficiency for BOD5 and COD in this integrated aerobic-anaerobic pilot 95.24 and 94.8 percent, respectively.
A. Kheyrandish, S. F. Mousavi, H. R. Ghafouri, S. Farzin,
Volume 23, Issue 4 (12-2019)
Abstract
In this research, conjunctive and integrated operation of surface and ground water resources of Behbahan plain (Maroon dam's reservoir and existing wells, respectively) was investigated. Simulation of allocation of water demands in this basin was performed by four scenarios, using WEAP software: 1) current conditions (M1), 2) reference scenario for the next 16 years (M2), 3) land development scenario (M3), and 4) optimal scenario (M4). The optimal scenario was performed with multi-purpose linear programming. Based on the results, drinking water demands was satisfied completely in all scenarios. Under the scenario of current conditions, all agricultural demands, except the traditional rights, supplied more than 50% in the low-flow months. In the reference scenario, water supply for agricultural demands in some months was less than 100% and even in June and July, the water supply for North and South Irrigation networks of Behbehan plain was less than 10%. In the land development scenario, agricultural demands of all irrigation networks, except Ramhormoz network, satisfied more than 90% in all months. The optimal scenario performed better than other scenarios for minimum Maroon River flow and volume of storage in the reservoir. Comparison of the four scenarios in satisfying the environmental needs also revealed that the optimal scenario performed better than the other three scenarios in the spring months. However, it provided less than 100% of water needs in the whole year. Comparison of the four scenarios also showed that the first two scenarios had the highest reliability percent in the Jayzan-Fajr, South Behbahan and North Behbahan Irrigation Networks and traditional water rights. Frequency of storage-time-probability from the storage volume in the optimal scenario also showed that maximum storage lifetime of the lasting storage volume was 558 million m3 (which was equal to half of the volume of Maroon dam’s reservoir) with the highest probability (60%).
