جستجوی مقالات مرتبط با کلیدواژه "طراحی" در نشریات گروه "آب و خاک"

Channel design is one of the optimization issues aiming to minimize the cost of channel construction. In this definition, the amounts of sections variables, namely radius, slope side, bottom width and flow depth are calculated by minimizing cost of channels with regard to indicating the hydraulic flow constraint. In the current study, the optimal design problems are formulated in a nonlinear optimization framework with the objective function being a cost function per unit length of the channel has been expressed as the cost per unit length of the channel for lining, the depth-dependent unit volume earthwork cost and the cost of water lost. Using genetic algorithm, the parameters of four optimized channel sections including trapezoidal, rectangular, triangular and circular sections of channels were calculated. From the results obtained for restricting the flow equation in comparison with the total cost of construction of sections, circular section has less cost of construction. Using the proposed method, which has more precision and accuracy, several models with additional restriction of velocity, Froude number, and top width were considered for optimal design of the channel under special conditions. Restriction of velocity and Froude number caused increasing by %40 and %30 respectively, but restricted top width decrease about %48 of construction cost for trapezoidal, rectangular, and triangular sections. Restriction of Froude number, top width and velocity caused increasing, the cost construction of circular section.

Channels are considered as one of the most important system of water transporting for irrigation purposes, drinking water consumption and flood control. Hence optimizing the design of channel structures can reduce the total cost of a channel. The objective function referred to the costs of channel structures. For this end, Manning equation has been used as an equality constraint. The optimization process was applied in various scenarios for two types of compound channel. The first type of trapezoidal channels had different side slopes, roughness coefficients and the second type was the main channel with side sections having different roughness coefficients. The optimizations were performed using genetic algorithm with depth, bottom width and a side slope variable. The influence of Manning roughness coefficients variation on construction costs for the two types of channel were analyzed. It was inferred that by increasing the roughness coefficients, the cost was increased. Several models with additional restrictions of Froude number, velocity of flow and the top width for the first type of channel were investigated. The results indicated that, Restriction of velocity and Froude number caused increasing cross section area and the cost construction.

Due to low rainfall and high evaporation in climatic conditions of Iran, improper management of irrigation practices has resulted to salinity and waterlogging of many lands. By attention to importance of the research on drainage issue and drainage problems of 20,000 ha agricultural lands in Moghan region, this research was conducted to identify the appropriate equation for determining subsurface drains’ spacing (s.d.s.) in an experimental field with the area of 18 ha, located in section 807, branch 3, of Agro-Industry of Moghan. Three drainage systems with spaces of 50, 100 and 150 meters between the drainage pipes having 200 meters’ lengths, were constructed in the experimental field. After beginning the irrigation, the measurements of water levels and drainage out-flows were performed. Comparison of the methods for determining the suitable distances between the subsurface drains showed that the Hammad, Bouwer & van schilfgard and vanschilfgard equations showed the most accurate results with 3, 6 and 7 average deviation percentages from subsurface drains’ actual spaces, respectively. Among the conventional equations for determining the s.d.s., the Bouwer & Vanschilfgard, Dumm, Glover and Vanschilfgard equations were recommended, respectively. The accuracy of these equations did not have a considerable difference with each other. Although, the efficiencies of the established drainage systems with 50 and 150 meters’ distances between drains were approximately identical, a system with 100 meters’ distance for drains was recommended to increase the degree of reliability.

Paddy fields development and renovation as the most important project to improve infrastructures of the rice sustainable production in North of Iran have had very slow Implementation pace due to various reasons and so that the project has been executed in less than 60000 hectares out of total paddy fields in Mazandaran province. Therefore, identification and prioritization of design, execution and operational problems is the basic requirements to change the existing situation. this research consider comparative comparison method between the design and as-built drawings, field monitoring of operating difficulties as well discussion and interview with experts. Then finalized list of problems, which used to develop a questionnaire with seven inquiries based on the Analytic Hierarchy Process (AHP). It contains four main indicators employers’ arrangements, design, execution and finally, operation and maintenance. So, 35 experts of paddy fields Development and Renovation were selected (from Jihad-e-Agriculture Organization, consulting engineers and the contractors) to fill out the questionnaire. The results indicate the fundamental limitations in order of priority are: failure to provide the timely required credits, the lack of integrated viewpoint on irrigation and drainage studies, the lack of f operational organizations same as agricultural NGOs, deficiencies in farmers training which needs for proper operation and maintenance of the projects and legal problems especially when private property is incompatible with the public profits. Therefore, serious offers of this research are change in the financing method of the projects, for example e use of combination of native and foreign countries finance, build of all layout components of project and use of other constructing project procedures such as EPC (Engineering Procurement Construction).

Today, due to the decrease in water resources, the authorities intend to increase application of modern irrigation systems in farms and gardens. Therefore, evaluation and monitoring of drip irrigation systems are performed with the goal of improving systems performance. For this study, 20 samples of implemented drip irrigation systems in different cities of Golestan province have been studied in 2011-2012. The evaluation has been performed based on the guideline of Soil Conservation Service (SCS). Measurements in any field were included pressure and discharge of emitters, check the status of the central control, applied water, wetted area, water quality and talk to farmers about the state of the system strategy. The results showed that average amounts of emission uniformity (EU), statistical uniformity coefficient (UC), efficiency reduction factor (ERF), potential application efficiency of low quarter (PELQ) and application efficiency of low quarter (AELQ) were 79. 85, 90, 65 and 73%, respectively showing that the performance of drip irrigation systems is average. In general, the main problems of drip irrigation systems in the province can be classified in four main categories based on, design, implementation, management and operation of social and natural division, in each of which the most important are design and improper implementation, lack of cleaning filters, clogging and improper number of emitters, not-adjustment of inlet valve on manifold, inappropriate pressure and its nonuniform distribution, low wetted area and extreme weakness in operation management by the users.

Artificial open channel structures are expensive infrastructures in terms of their materials, construction and maintenance. Design of a minimum cost channel section involves minimization of the sum of costs per unit length of the channel, subject to uniform flow condition in the channel. In this research, the objective function was expressed using the cost per unit length of the channel for lining, the depth-dependent unit volume earthwork cost, and the cost of water lost due to seepage and evaporation. A general resistance equation was used as an equality constraint. Optimal design of trapezoidal channel sections using genetic algorithm with depth, bottom width and side slope variables was accomplished. Two methods and several Models were evaluated including no restriction and restriction on normal depth, velocity of flow, side slope and top width. Restricted depth, velocity and side slope resulted in higher costs. However restricted top width resulted in lower costs comparing with other models. Also, another model was employeed which used the Manning equation as an equality constraint.

The issue of crisis management in countries and communities is one of the most important challenges in the past and present time for human beings. So far, in countries and communities, there have been many attempts to increase the managerial power especially in the encountering stage, but these attempts have had many advantages and weak points. This research deals with inspecting and studying the existing theories and models and the specific conditions of Golestan province, esp. the natural disasters for flooding and firing, which have been the most frequent problems in this province in the encountering stage particularly in managerial dimensions including conditions of decision making, principles of coordinating and gathering sources and facilities and communications and alarming systems. It also seeks for a definition for the function and conditions of the role of these managerial dimensions to help the managers of this province in encountering natural crises. The objectives and Methods discussed in the present study are applicable and analytical. On the other hand, it should be pointed out that the research pattern and criterion extracted from theoretical bases, have been investigated and approved by using a survey program involving 15 experts. The statistical society of the research involves 300 individuals from managers and experts and Golestan management Coordinating Council and Subsidiaries cities, which on that base the number of calculated statistics is 81. To analyze the data collected, SPSS software and multivariate regression analysis and Friedman test was used. The investigation to calculate face validity of the components dimensions and the relationship between them and also the amount of validity of each component variables, besides, the mutual effects and prioritization of the aspects and components, were calculated quantitatively using SPSS software and multivariate regression analysis and Friedman test. Finally, Golestan natural disaster management model involving aspects of decision making and the alpha coefficient 0.326 (The components of threat, time pressure, surprise) principles of coordination and the alpha coefficient 0.305 (the component of unity of command, Command Line, gamut monitor) mobilize resources and the alpha coefficient 0.292 (Component of the resource, type of resource, resource capacity, quick access resources) and warning systems and information and the alpha coefficient 0.288 (The components of the collection of information, public information and awareness within the organization) were approved.