Original Article
Abstract
The quality of human life is directly affected by water resources planning and management. Major portion of this resources used for agricultural purposes. Irrigation networks that are built to provide water needed for agriculture, have significant role in efficient use of water resources. Many years ...
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The quality of human life is directly affected by water resources planning and management. Major portion of this resources used for agricultural purposes. Irrigation networks that are built to provide water needed for agriculture, have significant role in efficient use of water resources. Many years have passed since the construction of the irrigation networks, most of them have shown low performance; Therefore, improvement of existing irrigation networks to improve their performance is essential. Involvement of so many components in irrigation networks rehabilitation and their complex interactive relation on system performance, requires a long term, integrated and systemic. Recently, system dynamics approach have been used for irrigation networks rehabilitation studies. Considering the importance of farmrs' participation and management improvement on performance of irrigation networks, in this paper, the system dynamics model of Qazvin irrigation network was completed with regard to these issues. In addition to physical aspects of irrigation networks, managerial and social issues through various policies for the improvement of irrigation networks are considered. The results showed that with the current trend continues, performance of Qazvin irrigation network will be worse in the future and will be declined about 10% by the year 1399. Various policies such as physical and managerial improvement or increasing farmers participation has different impacts of performance improvement. Physical and managerial policies have improved the performance about 5% and 3% by the year 1399. Farmers participation showed highest impact on performance improvement which is about 14% by the year 1399.
Original Article
Abstract
The Imam Khomeini sugarcane agro-industry plantation is one of ten sugarcane plantations in Khuzestan province. Today, salinity has been lowered to well below crop salt tolerance level, but deep subsurface drainage and over-irrigation has occurred and deposits a significant amount of drainage water back ...
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The Imam Khomeini sugarcane agro-industry plantation is one of ten sugarcane plantations in Khuzestan province. Today, salinity has been lowered to well below crop salt tolerance level, but deep subsurface drainage and over-irrigation has occurred and deposits a significant amount of drainage water back into Dez River each year. This study investigated the impact of controlled drainage on the reduction of irrigation water, soil salinity, drainage volume, salt load and sugarcane yield for two fields. One field had free drainage (FD) and the other had controlled drainage (CD). In the CD system, water depth control level was 90 cm below the soil surface. Results showed that the amount of irrigation water for CD decreased by 27% and reduced total drainage outflow by 55%. During this time, the CD the salt load decreased about 24 ton/ha and crop yield increased 8.7%. Controlled drainage significantly reduced the amount of irrigation, drainage volume and salt load over the free drainage system. This method is a feasible solution to decreasing river pollution and has a positive hydrological and environmental impact.
Original Article
Abstract
The present study compared the chemical, physical and sensory properties of textured skim milk with skim and whole milk over 1, 3, and 5 days of storage at 4±1 °C. A skim milk sample was heated at 60°C for 15 min, then 0.4 ml of rennet solution were added to 100 ml of the milk. The milk ...
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The present study compared the chemical, physical and sensory properties of textured skim milk with skim and whole milk over 1, 3, and 5 days of storage at 4±1 °C. A skim milk sample was heated at 60°C for 15 min, then 0.4 ml of rennet solution were added to 100 ml of the milk. The milk and rennet mixture was then pasteurized at 65°C for 30 min to deactivate the rennet. Skim, whole and textured milk samples were tested for pH, titratable acidity, protein, fat and total solids and colorimetrics, viscosity, appearance, structure, texture, taste, flavor and overall parameters on days 1, 3 and 5 of storage in a refrigerator. The results revealed that values for the chemical properties of the textured skim milk fell between those of the skim and whole milk for all storage times. The textured skim milk also showed greater viscosity, higher whiteness, yellowness and greenness values than did skim milk (p>0.05). Panelists scored textured skim milk higher than skim milk and nearly identically to whole milk. Overall, textured milk was found to have properties similar to whole milk and remains stable over 5 days of storage. For industrial purposes, this product can be simply produced by limiting rennet activity.
Original Article
Abstract
The importance of dietary fiber in normal and therapeutic diets has been acknowledged by numerous authors in recent years. Dietary fiber has different physiological effects on human health. The recommended daily intake of dietary fiber is about 30 g, but less than this is often consumed. Wheat bran is ...
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The importance of dietary fiber in normal and therapeutic diets has been acknowledged by numerous authors in recent years. Dietary fiber has different physiological effects on human health. The recommended daily intake of dietary fiber is about 30 g, but less than this is often consumed. Wheat bran is an excellent source of dietary fiber and is used to fortify foods. The nutritional benefits of fiber have led to an increase high-fiber bread; however, incorporating wheat bran into dough changes its properties. In this study, digital image analysis was used to measure bran particle size. Both small and large bran samples were prepared. The effect of processed small bran on dough rheology during mixing was determined using a farinograph. Water absorption, dough development time, stability and the valorimetric value of dough containing hydrothermaled bran increased about 1, 15, 50 and 10 %, respectively. The treatment decreased the degree of softening from 120 to 70 BU and increased fiber content 25%. The results indicated a reduction in glutathione content of about 55% in hydrothermaled bran.
Original Article
Abstract
Flaxseed is rich in omega-3 essential fatty acids, lignans, dietary fiber and natural antioxidants such as tocopherols. Because of its functional effect in preventing disease, flaxseed is used as an ingredient to fortify food formulations. Bread is a major food product in Iran. Fortification of wheat ...
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Flaxseed is rich in omega-3 essential fatty acids, lignans, dietary fiber and natural antioxidants such as tocopherols. Because of its functional effect in preventing disease, flaxseed is used as an ingredient to fortify food formulations. Bread is a major food product in Iran. Fortification of wheat flour with ground flaxseed makes use of the healthy benefits of flaxseed. This study investigated the rheological properties of dough prepared using flaxseed-supplemented flour. Flaxseed flour was used to replace 50, 10, 150 and 200 g.kg-¹ of the wheat flour. Farinograph results showed greater water absorption, longer development time, increased softening and a higher farinograph quality number for the flaxseed-supplemented flours over the control flour. Dough stability time for all blends decreased except for that with 5% flaxseed. Extensograph testing revealed a significant increase in maximum resistance of dough to extension and a substantial decrease in dough extensibility and extension energy. Despite the beneficial health effects of flaxseed in fortification of bread, the negative effects of high concentrations of flaxseed powder on dough quality and rheological properties must be considered and precautions taken to compensate for these adverse effects.
Original Article
Abstract
Agglomeration followed by pelleting is an efficient method to decrease transport costs and increase economic efficiency of composting municipal waste. The moisture content of compost is the most important parameter of the pellet making process for any type of manufacturing device. The experiments in ...
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Agglomeration followed by pelleting is an efficient method to decrease transport costs and increase economic efficiency of composting municipal waste. The moisture content of compost is the most important parameter of the pellet making process for any type of manufacturing device. The experiments in this study were done at moisture contents of 35%, 45% and 50% at extruder shaft rotational speeds of 100, 150, 200 and 250 rpm. The materials were first processed using a mixer and kneading device then made into pellets using a single screw extruder. The durability of the pellets at different moisture contents were tested to determine the optimum moisture content and its effect on the properties of the pellets. The results showed that moisture content of the compost, rotational speed of extruder screw and the interaction of these parameters significantly affected the durability of the pellets. Durability increased from 35.86% to 78.29% as moisture content increased from 35% to 45% (w.b.). Durability was increased significantly at all rotational speeds as moisture content increased from 35% to 45% (w.b.). Increasing the moisture content produced no significant effect for the strength of the pellets at a rotational speed of 150 rpm. The strength was higher at 35% moisture content than for 45% moisture content.
Original Article
Abstract
During onion harvesting, removing leaves from the onion bulbs is a time- and energy-consuming operation that is currently done manually on most Iranian farms. Roller-type toppers can be appropriate devices for onions that are already undercut and gathered. The machine parameters of rotational speed and ...
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During onion harvesting, removing leaves from the onion bulbs is a time- and energy-consuming operation that is currently done manually on most Iranian farms. Roller-type toppers can be appropriate devices for onions that are already undercut and gathered. The machine parameters of rotational speed and clearance between rollers have significant impacts on machine performance. This study developed a rolling topper and evaluated the effects of rotational speed (100, 150, 200, 250 and 300 rpm) and the clearance between rollers (23, 33 and 43 mm) on the percentage of damaged bulbs, number of bulbs oriented in the appropriate direction and forward speed of the bulbs on the machine. Results showed that the greatest percentage of damaged bulbs (31.8%) occurred where clearance between rollers was set at 43 mm. Increasing the rotational speed enables movement of bulbs at higher forward speeds along the rollers; however, increasing the forward speed of bulbs increased the percentage of non-oriented bulbs to 24% at a rotational speed of 300 rpm. A rotational speed of 200 rpm and 23 mm in clearance between rollers was found to be the optimum configuration for a roller-type topper. In this case, a two blade mechanism decreased the height of remaining leaves after cutting (6.52 mm) and increased the number of onions topped at the appropriate distance from bulb base (95.5%), which was more effective than blade and idler mechanisms.
Original Article
Abstract
This research designed, constructed and evaluated a map-based variable rate application system for liquid nitrogen fertilizer. Solenoid valves were used to change nozzle flow using pulse-wide modulation technology. A turbine flow sensor and GPS module were used to measure solenoid valve flow and online ...
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This research designed, constructed and evaluated a map-based variable rate application system for liquid nitrogen fertilizer. Solenoid valves were used to change nozzle flow using pulse-wide modulation technology. A turbine flow sensor and GPS module were used to measure solenoid valve flow and online system coordination, respectively. The graphical user interface software was designed by Visual Basic 6. This program received online coordination from a GPS module, received fertilizer map data, compared online and map coordinates, specified application order, received sensor output and compared it with optimum data and then applied proportional closed-loop control. To evaluate the system, accuracy and time-delay experiments were carried out with 3 replications. The results showed that the average difference between map data and system flow for open and close-loop controllers were 10.0 and 3.6%, respectively. The maximum time delay was 0.54 s. Results also showed that, at 1% probability, no significant difference was observed between the system flow and nitrogen fertilizer map data.
