Year:2003 | Volume:8 | Issue:4|Papers Count:8

Cost of repair and maintenance is small part of the cost of machinery usage. Cost estimation of repair and maintenance of agricultural machinery is very important for replacement and net return of management of machinery. It is also an important factor on cost of machinery; therefore, a mathematical model is presented for the cost predication of repair and maintenance. However, there are three models for three different areas of Iran.In order to present a mathematical model for the cost predication of repair and maintenance of MF and Universal 650 (U650) tractors in Kermanshah province. First of all a questionnaire including driver's information and technical data for the tractors was completed by randomly sampled tractor driver. The fifty Universal 650 tractor questionnaires and seventy MF tractor questionnaires was gathered in summer of 1379 (2000). The provided data was entered to a SPSS and Excel computer softwares. The data was analyzed for the comparison of cost of repair and maintenance for MF and U650 tractors, determination of models with test statistics f, and coincident of determination, R2 and comparison of model with other studies.Cost of repair and maintenance of U650 was higher than MF tractors Average cost of repair and maintenance for U650 tractors was higher than MF tactors at 5% confidence level. Regression analysis and f-test selected most appropriate power model as TAR=1.1 (Tauh)1.6 The model was compared with other existing models (ASAE standard, Sharifi, and Sabatei) at 5000 and 1000 total annual hour usage. This study's model showed the cost of repair and maintenance index was more than ASAE model hut less than the other two models.

In order to investigate yield of hairy vetch (Vicia villosa) in intercropping with cultivars of wheat, an experiment was conducted for two growing seasons in Borzolabad dryland research station. Experimental desing was a split plot in a form of randomized complete block desgin with three replications. Treatments were: irrigation regimes (non irrigation, irrigation in at the time of sowing and irrigation at the time of an thesis), wheat caltivares (Sardari, Malaghani, and 1:1 weight - based mixture of two), and different seed ratio of wheat and hairy vetch (pure stand of wheat cultivars and hairy vetch, %75 wheat: %25 hairy vetch, %66.7 wheat: %33.3 hairy vetch and %50 wheat: %50 hairy vetch). Results showed that supplementary irrigation at the time of an thesis of wheat increased yield of hairy vetch. Yield of hairy vetch in mixture decreased due to competition with wheat. Yield of hairy vetch in pure stand was highest and lowest in %75, %25 seed ratio. In two years of experiment cultivars of wheat showed not significant effect on yield of hairy vetch. Supplementary irrigation and seed ratios had no significant interaction effect on hairy vetch yield.

Cotton is one of the most important agricultural commodities in Iran which, in spite of the government policies and emphasis on self -sufficiency and non-oil export exchange earning, has lost its previous ranking in the country.The decline and fluctuation in cotton production and export and also increase in the domestic consumption, due to population growth, have even necessitated the import of this commodity in some recent years.In this paper, the performance and efficiency of the government policies; currency valuation, inputs subsidy, and the announcement of purchasing guaranteed price are studied by using the policies Analysis Matrix which is applied to 1998 data.The results show although the policy of inputs subsidies has protected the producers to some extent but on the other hand, the policies of under-valued currency and guaranteed price fixation have even damaged the producer's position. As a result the cumulative effects of these policies have biase toward production and have caused the producers to be taxed. The results also show that the country has comparative advantages in production and export of this commodity.Therefore, it is suggested that in order to protect a commodity it is necessary to work out the cumulative effects of various policies instead of considering each policy in isolation.

In a biological experiment, 390 day old male Ross broiler chieks were used in a completely randomized design with five treatments and three replicates for seven weeks period to investigate the effect of different levels (8 and 16) of high and low fibre sunflower seed meal on broiler performance. All diets were compared with control group (without sunflower seed meal). No significant different was found in weight gain and feed intake among treatments in comparison with control group. Results showed that feeding 16% low fibre sunflower meal significantly increased feed conversion ratio in comparison to control group (p<0.05). The relative weight of gizzard with increasing level of sunflower seed meal in the diet increased but this difference was only significant in diet with 16% high fibre sunflower seed meal. Protein efficiency ratios were measured for all diets and statistical analysis showed that there is a significant difference between 16% low fibre sunflower meal and control group (p<0.05). Economical comparison of diets showed that the cost of live weight production in all treatments containing sunflower seed meal were higher than control group.The results indicate that feeding up to 16% high fibre sunflower meal in broiler diet has no adverse effect on broiler performance and carcass quality.

In these study moisture sorption isotherms curves for pistachio powder were obtained in 15, 25, 35 and 40°C, respectively. The curves related to pistachio kernel and whole pistachio was obtained in 15 and 35°C as well.Hysteresis phenomenon was observed in water activity range of aw: 0.2 to 0.7. The level of hysteresis decreased in whole pistachio, pistachio kernel, and pistachio powder respectively. Some mathematical models were studied for fitting of pistachio equilibrium moisture content (EMC) including BET, GAB, Smith, Sowing, Halsey and Henderson. Among these models, Smith model was found to fit the most properly on the experimental results. Thermodynamic relationship of Clausius -Clapeyron was used to determine the isosteric heat for adsorption and desorption of pistachio moisture. The results were sketched upon moisture content on dry basis.The results of this study will be used to optimize the drying process, storage conditions and packaging of pistachio nuts.

This study was did in ruined forest at south-eastern Rudsar township of Gilan province area. This research was studied different factor effects of plant species such as kind of plants and per cent of plant crown cover, different factor of soil such as depth, density, angle of intral friction, cohesion and intra pressure of water and geographical factors such as slope, length and wide of area on create of landslides.With do this research was distinguished for area with more than 27 degree with three studied species of tree (Iron tree, Hony locust tree and Citrus) and one shrub (Tea) that is planted under citrus garden in destroyed forest, the Iron tree suitable for stability of soil mass. The hest land use was advised forestry for area with more than 18 degrees and agriculture for less than 15 degrees.

There are various factors affecting the consumption of thermal & electrical energies in timber kiln drying process. In the present survey, all of the affective factors based on an applied and generalized model for related industries were studied at first.Then, the appropriate equations were specified, investigated and inter-related in order to estimate the influence of each parameter on the consumption of energy during the process of kiln drying. To this end, being familiar with the following matters is necessary: Acquaintance with different materials types of kiln as well as their basic specifications such as type of utilized constructional materials, heating systems and the kiln function; the main principle of kiln drying heat transfer, the air psychometric specifications, the equations relating temperature, relative humidity & humidity ratio; the ways of computing volume and rate of ventilation; different kind of fans & their specification and equations governing their function. At last, after Calculating Energy Consumption through a case study and Comparing the results with those attained by the other researchers, practicality of the the utilized mathematical equations and model were Confirmed.