جستجوی مقالات مرتبط با کلیدواژه « efficiency » در نشریات گروه « عمران »

In the third millennium, cities have of a great potential as the engine of Social growth and development. Urban management, therefore, should pay attention to its internal structures and processes to achieve sustainable development In Iran, rapid population growth -with 70% of urban population- and misallocation of resources and facilities on the one hand, and financial self-sufficiency of the municipalities on the other hand, has broached more than ever a need for assessment of performance in order to improve and promote management. Considering the role of municipalities in organization of urban management, it is necessary to use scientific methods for improvement and promotion of urban management in different economical, social and environmental fields and in line with urban sustainable development. In this research, the goal is assessment of performance in Karaj Municipality and Deputies then rank ranking them. therefore, a model of Network Dara Envelopment Analysis (NDEA) technique has been used to assess the efficiency of municipalities according to internal structures. The results of the model after collecting the data by considering five input and 12 output variables illustrated that in 2014, more municipalities were efficient. furthermore, district 5 in 2014, district 4 in 2015, and districts 1, 4 and 5 in 2016 were efficient. The municipalities of districts 4, 8, 11 and 12 have achieved the best performance in the technical and civil depute during these years

Every country with any level of development seeks further development. In this article, by presenting an innovative method derived from the concept of work and its relationship with power and the direction of its application, a new approach to development indicators and especially the Inclusive Development Index (IDI) is proposed. This method is a development on IDI that takes economic, social and environmental aspects into account.For this work, countries were grouped based on their IDI pattern and analyzed to quantify the compatibility of national resources used with planned development strategies. The results obtained for each country provide an insight into whether the use of additional resources can further improve the development index or the need to revise or change the planned strategies before taking any further action.Subsequently, based on the water and green growth model that is proposed for institutional evaluation and analysis of policy instruments, the projects of Iran's water sector were evaluated. This analysis was done based on questionnaires answered by university and industry experts. The final result reveals the need to review the strategies and programs of the country's water sector.

In the current situation of the country, the most important necessity is the use of new construction technologies due to its important role in sustainable development. Higher manufacturing speed than traditional methods has made it possible to prepare more units for operation in less time. The purpose of this research is to study new construction technologies in terms of efficiency in Iran and to select the best method based on FAHP fuzzy hierarchical analysis. The research was applied in terms of purpose and descriptive-survey in terms of data collection, and the research data were analyzed using a hierarchical method. The data collection tool in this field research is a questionnaire. The statistical population of this study was members of the Yasuj Building Engineering System Organization. Random sampling method was used. Morgan's table was used to estimate the sample size, which is equal to 100 people. The results showed that the most important factors in the study of new construction technologies in terms of efficiency in Iran and selecting the best method from the strongest to the weakest, respectively, are the priority of green roof technology, durable frame system, nano building coatings, biological concrete, windows and walls. Thermochromic, cold rolled light steel frame system, two-shell facades, solar panels and trade panels..

The issue of increasing efficiency and improving the executive performance of construction has been one of the goals and concerns of regulatory bodies such as the municipality and the Engineering System Organization. At First, what is taken from the executive supervision concept is that the presence of the building's supervisor is the main responsibility for ensuring the building's quality. But in reality, there are countless factors behind of a building construction process that cause a decrease in the quality of executive supervision and ultimately a decrease in the executive quality of a construction. The main purpose of this article is to review the defined role of the supervising engineer by the Engineering System Organization in the field of construction, to examine various factors in the decline in the quality of executive supervision by statistical data obtained from the community and finally suggestions to increase the efficiency of executive supervision.

In this paper, copulas and Archimediean copulas (especially with hyperbolic generator) are investigated and it is shown how to use this type of functions in the stochastic frontier analysis. Then we study the efficiency of hydropower plants located on prominent dams in Iran, and based on their performance in 1399 we use data envelopment analysis and stochastic frontier analysis and copulas functions to rank them. In the present study, among the 58 mentioned dams, the dams with an average practical production capacity of at least 10 MW are evaluated. The number of these dams is 29. The calculations show that Gotvand Dam is in the first place and the Mulla Sadra dam has the last rank.

Water pumping stations usually use fixed speed pumps that have a good efficiency over a small range of pressure and flows. If different flows and pressures are required, unsuitable pump speeds will yield excessive energy losses. This imposes additional costs, especially on pressurized irrigation systems, which are constantly changing their irrigation needs, sometimes monthly. In pressurized water distribution systems, a constant speed pump is often used because of its simplicity. However, constant speed pipes are not easily able to deal with changing demands in water flows. When the demand for the discharge differs from the design discharge, the required demand (discharge and head) could be met by changing the pump speed without making any special changes in the system. Using an electronic drive circuit, the electrical frequency can be changed and the rotation speed of the pump motor can thus be modified. In this study, the application of variable speed pumps in pressurized irrigation systems is investigated. Two pumping station scenarios including a fixed speed pump and a variable speed pump are considered. The results show that using a variable speed pump increases the average pump efficiency by 18.7%. In addition, the variable speed pump system reduces the electrical consumption 57.6 % compared to a fixed speed pump. Therefore, the use of variable speed pumps in pressurized systems is recommended.

Given the importance of the repair and maintenance process in keeping equipment and facilities ready for use, it is necessary to assess the process and performance of maintenance indicators regularly so that the repair and maintenance is planned and upgraded. The main purpose of the building repair and maintenance is to control the equipment, facilities, and various building components to determine productivity and optimize their ability to achieve the highest efficiency. As measuring the efficiency is one of the most important performance evaluation methods, evaluating the efficiency of the repair and maintenance is one of the qualitative factors to improve this system. The purpose of this study is to evaluate the efficiency and performance of the repair and maintenance in buildings using a quantitative and provable data envelopment analysis (DEA) method. The results of this study show that the DEA is a suitable method for evaluating the efficiency and productivity of the decision-making units (DMUs).Therefore, first, the questionnaire is formed based on the building repair and maintenance system parameters extracted from Topic 22 of the National Building Code, the ranks are determined, and the results obtained from the sub-indices are integrated by the mean ranking index, and the qestionnaires’ reliability is measured using Cronbach's alpha. Finally, after defining the input and output indices by the DEA, the efficiency of each building and its cost are determined based on the repair and maintenance indices(In a case study of the city of Karaj). The results showed that the minimum and maximum reduction of the cost of charging, maintenance and repair of the building to convert them into an efficient building is 1% and 80%, respectively. Moreover, based on the results, it is possible to provide suggestions to improve the efficiency of the inefficient buildings based on the repair and maintenance costs.

Nowadays, all managers in all organizations want to make optimal use of facilities and capacities in various departments. Therefore, the existence of a model to provide feedback on destructive factors in bridges with the aim of improving the management of concrete bridges and obtaining a tool to satisfy the needs of managers, seems very necessary and logical. In line with the above necessity, concrete road bridges under the supervision of the Highway and Road Transportation Organization of the country will be selected as a statistical sample and the performance of concrete bridges will be compared with each other using data envelopment analysis (DEA) method. In order to evaluate the performance of bridges, efficient and inefficient bridges are determined and the effective factors in their inefficiency are determined. In order to evaluate the efficiency of inputs such as weather and traffic conditions, and the outputs including structural failure factor and serviceability were examined using the input-axis CCR model through DEA-Master software. The results showed that 35 bridges out of 384 concrete road bridges measured in the main axes of Zanjan province have strong performance and the average efficiency of these 384 bridges is 0.98 out of 1.Also, the 8 km bridge of Zanjan-Qazvin freeway is the most efficient bridge in terms of threat of reference times.

Air transport is an important component of the transportation industry of any country and airports are considered as one of the key inputs of this industry. Therefore, it is crucial to assess the performance and efficiency of airports and take appropriate measures to increase their efficiencies. To that end, in the present study we use stochastic frontier analysis approach to examine the technical efficiency of selected international airports in Iran (i.e. Mehrabad, Mashhad, Shiraz, Tabriz, and Isfahan airports). The findings using the data for the period 2010-2015 show that 98% of the inefficiencies observed in these airports are due to the technical inefficiencies. In addition, none of the airports under study had achieved the complete efficiency and the lowest efficiency is observed in 2015. The results also indicate that Mashhad and Tabriz airports ranked first, with the highest efficiency among the five selected airports. Isfahan and Mehrabad airports ranked second and last, respectively.

There are many factors which may cause victory in an organization while different concept of victorious might exist  depend on the organization. One of the impressive one is efficiency which is not  related to organization type and each management unit must consider methods to increase efficiency. Ergonomy will be effective to efficiency index growth, cause better function in every organization. Ergonomy principles incorporate ways which can protect people mental and physical  heath, also motivate employee. These principles could  lead  person to higher level of  needs and force them to attempt to achieve self-esteem and  development by Ergonomy effects on  increasing efficiency has examined  in variety of organization  and it has proved its principles cause better function in any organization

Submerged vanes are flow-pattern altering structures that are mounted vertically on channel-bed at a small angle of attack to the approach flow. A submerged vane generates a secondary circulation (a spiral flow), due to the vertical pressure gradients on the two sides of the vane, which originates below the top elevation of the vane and extends in the downstream of the vane. The vane-induced vortex redistributes sediment within the channel cross section and changes the alluvial bed profile. However local scour around the vanes is one of the problems in using of submerged vane technique.
The extension of local scour hole is related to the shape of the vanes.Primary submerged vanes are generally flat rectangular plates. In the present research, cutting a part of the leading edge of the vanes out is investigated as a countermeasure in reducing the local scour. Studied vanes include a rectangular vane (as the baseline vane), and five other modified vanes with tapered leading edges with angle of  = 30°, 45°, 60°, 70°, and 73.3°. The present study aims to evaluate the effect of this modification on the vertical velocity components at the leading edge and strength of the secondary circulation in the downstream of the vanes. In this research, Flow-3D numerical model, version 10, is used to study the flow field around the vanes.

The commercial CFD model Flow-3D was used in this research. Experimental velocity measurements were used for calibration of the model. For this purpose a re-circulating flume (7.30 m long by 0.56 m wide by 0.6 m deep) was used. A centrifugal pump discharged the water into the stilling tank at the entrance of the flume. In order to create a uniform inflow of water, a screen was placed at a distance of 1 m from the flume entrance. A tail gate was used to adjust the depth (do) of water in the flume to a constant value of 0.25 m.The dimensions of the vanes were determined using Odgaard’s (2008) design criteria: a vane height-to-water depth ratio of Ho/do = 0.3 and length of L = 3Ho. A mean flow depth of do = 0.25 m yielded Ho = 0.075 m and L = 0.25 m. velocity measurements carried out using vanes V0 and V3 at a flow Froude number of Fr = 0.16. In each test, the vanes were installed on the centerline of the flume at an angle of 20° to the flow.In order to investigate vane-induced velocity field, 4×4 cm2 grids across the flume were taken at the center of the vanes. At each grid point, three-dimensional components of velocity vector (u, v, w) were measured by means of an electromagnetic velocimeter (EVM). Velocity very close to the walls of the flume was not measured.

On the high-pressure side of the vanes, vertical velocity components are upward (positive) and on the low-pressure side are downward (negative). Therefore a clockwise secondary circulation is generated at downstream of the vanes.Downward velocity components at leading edge of primary rectangular vane (vane V0) are obvious. By cutting parts of leading edge out of vane V0 for tapered vanes V1 and V2, the magnitude of negative w-velocity components is reduced by 40% and 69%, respectively. By increasing the taper angle for vanes V3, V4 and V5, downward velocity components are diminished effectively.Moment of momentum (MOM) quantity is used in order to evaluate strength of vane-induced circulation. MOM values are applied for comparison of performance of the vanes. For this purpose, velocity data at two sections at the distances of 2Ho and 4Ho, i.e., 15 cm and 30 cm downstream from center of the vanes was used. In the calculation of MOM, 100 velocity components (50 v-components and 50 w-components) are used. Therefore this quantity is a useful criterion for evaluation of the performance and efficiency of the submerged vanes.

Velocity distribution and moment of momentum (MOM) of the vanes indicated the reduction of erosive negative velocity components at the leading edge of the tapered vanes. Based on MOM values, cutting the leading edge out of the vanes causes lower performance. In other words, this modification restricts the vane-influenced field of the tapered vanes relative to the rectangular vane (vane V0). Results show that performance of tapered vanes (V1 to V5), relative to the rectangular vane, (at distance of 2Ho) is reduced by 5.8%, 7.3%, 17.8%, 33% and 42.6% respectively; at distance of 4Ho the amount of reduction is 7.4%, 11.9%, 17%, 25.5% and 34.3% respectively. On the contrary, the efficiency of the tapered vanes is increased. The amount of increase at distance of 2Ho from the center of vanes V1 to V5 is 3.2%, 9%, 11%, 14% and 14.8% and at distance of 4Ho is 1.4%, 3.6%, 12.1%, 26.7% and 31.3% respectively. Therefore, if tapered vanes are used to reduce the local scour, big values for the distance between the vanes arrays (δs), according to the design criteria, are not recommended.

Selection of appropriate accelerograms for nonlinear dynamic analysis is one of the most important challenges due to their significant influence on the interpretation of analysis results. A rational method for initial refinement of ground motion records with a minimum computational cost is application of refining process based on an optimum intensity measure (IM) which is able to predict the structural responses in a reliable manner. In this research, a list of intensity measures is considered to determine most effective ones from the point of view of effective relation with the dynamic response of the structure. Selected models in this paper includes four two-dimensional (2D) reinforced concrete (RC) structures of 2, 4, 8, 12 and 20 story with special moment-resisting frame (SMRF) system, which are modeled nonlinearly. Collapse capacity of the structures was obtained using the intensity measure spectral acceleration at the first-mode period of structure Sa(T1) and the Incremental Dynamic Analysis (IDA) under the influence of 40 ground motion records selected from the refined data set to observe the gradual behavior of the structure from the linear stage to collapse. Finally, by establishing a statistical relationship between the dynamic response parameters and 27 intensity measures with the use of Pearson correlation index, the most effective intensity measure that All have an integral form and independent from the period of structure, for each of the selected structures was introduced. By examining the results, it can be said that for the 4 story low-rise structure, the Response Spectrum [Housner] intensity measure and for the 8 and 12 story mid-rise structures, the Housner intensity measure and finally, for the 20 story high-rise structure, the Displacement Response Spectrum intensity measure has the highest correlation among the intensity measures studied.

Labyrinth weir is one of the approaches to increase the discharge capacity. An arced ‎configuration improves the orientation of the labyrinth weir cycles to the approach flow and ‎increases the weir crest length for a given width. In this study, the effects of the entrance flow ‎conditions on the hydraulic‏ ‏performance of the arced ‎labyrinth weirs is studied experimentally.‎‏ ‏The effects of the angle between the entrance channel walls (Θ′) on the discharge coefficient ‎and the efficiency are investigated for different values of the ‎headwater ratio (Ho/P), the ‎downstream sidewall angle (α), and the weir arc ‎angle (Θ).‎ Experiments were conducted in a recirculating flume‏ ‏which is 10 m long, 2 m wide, and 0.9 m ‎deep at Tarbiat Modares University. To simulate the reservoir conditions, a specific setup was ‎added to the flume, known as the reservoir simulator. The flume was launched from its two ends ‎by two pipelines. The inflow passes from underneath of the reservoir simulator and enters into it ‎through a semi-circular opening in its horizontal‏ ‏wall. After moving‏ ‏over the horizontal‏ ‏wall, the ‎flow comes up through the gap between the vertical wall. Finally, it flows on the platform and ‎moves towards the downstream channel. All the plates (including the platform and the simulator ‎walls) have a semicircular plan-view with a porosity equal to zero. The‏ ‏weirs were mounted on ‎the platform at the entrance of the downstream channel. Totally 132 experiments were ‎conducted to investigate the effects of the mentioned parameters on hydraulic performance of ‎arced labyrinth weirs.‎ Due to the nappe interference, the local submergence forms in the downstream of the ‎labyrinth ‎weirs. The size‎ of local submergence regions increase by increasing the ‎headwater ratio ‎and the arc angle. However, vice versa trend occurs with the downstream sidewall angle. In ‎addition, for low values of the arc angle, the lateral flow from the side cycles to their adjacent ‎cycles produces the surface turbulences. The results ‎indicate that the discharge coefficient ‎decreases by increasing the ‎headwater ratio and the downstream sidewall angle. For low values ‎of the ‎headwater ratio, the discharge coefficient increases when the arc angle increases. ‎However, a decreasing trend is observed in high head conditions. By increasing the ‎arc angle ‎and decreasing the downstream sidewall angle, the efficiency of a labyrinth weir can be ‎increased. However, the efficiency gains diminish by increasing the ‎headwater ratio.‎ The efficiency of a labyrinth weir can slightly be increased by projecting of the cycles into a ‎reservoir for low values of Ho/P, α, and Θ. However, in the wide range of the research domain, ‎the efficiency decreases‏ when ‏the angle between the entrance channel walls increases. ‎According to the results of this research, the efficiency of a labyrinth weir can be increased up ‎to 20% by channelizing abutments in high head conditions. However, the effect of Θ′ is ‎insignificant for higher values of Θ. In addition, as α decreases, the benefits and the losses of ‎decreasing Θ′ become more ‎severe at higher and lower values of Ho/P, respectively.‎

Hydraulic Ram pump is a device which works without any external energy, and uses to pump water to a considerable height by using renewable energy of water hammer. Mechanism of ram pump cycle produces the water hammer phenomenon and managements of its energy for pumping water. Simple and inexpensive system, use of renewable energy and environmental sustainability, extended the hydraulic ram pump system in third world countries especially. The ram pump system has different component. The supply source of water including springs, rivers and natural streams, drive pipe with definite length and diameter and it has the task of transferring water from the supply source to the ram pump device, set of the ram pump consists two movable valves (impulse valve and delivery valve) and an air chamber. The delivery pipe has the task of transferring the pumping water to the tank storage. The ram pump performance is such that after doing the alternative cycle, a portion of input discharge is pumped to the delivery head.

A parameter that quantitatively represents the strength of a ground motion is called Intensity Measure (IM). The value of an IM for a given hazard level is the output parameter of Probabilistic Seismic Hazard Analysis (PSHA) which is used in structural seismic analysis. In other words, an intensity measure is a link between PSHA and structural seismic analysis. The main desirable features of an appropriate IM are efficiency and sufficiency. The importance of using an appropriate IM is that the seismic performance assessment of structures can be performed more realistically. In this study, the performance of different scalar IMs to predict the collapse capacity of low to mid-rise steel Special Moment Resisting Frames (SMRFs) was evaluated. For this purpose, 3, 6 and 9-story steel SMRFs designed for the SAC project were simulated by OpenSees and the collapse capacity of these structures were determined by using incremental dynamic analyses under 67 far-field ground motion records. After calculating the collapse capacity values by using scalar IMs existing in the technical literature which are classified into structure and non-structure specific IMs, the performance of IMs including efficiency and sufficiency with respect to magnitude, source-to-site distance, and average shear-wave velocity at the upper 30 m was compared.

Energy conversion efficiency of water to the water flow depends on the blade of the turbine wheel depends on the blade surface. Heat water in a collision with turbine blades, friction on the surface of the water during passage through the turbine blades, nozzle head loss and air friction resistance pelton turbine energy resources are wasted. When the water jet passes around the turbine blades, ideal against the current because of non-slip surface and thus the boundary layer is created. The formation of the boundary layer and its thickness depends on the blade surface roughness. In this research the mathematical relationships to help the border layer, a model for the calculation of the flow passing through the wasted power of pelton turbine blade is presented in which the effect of the friction and pressure changes on the flow along the path of the blade come into account.

Despite Airports importance as the main air transport infrastructure, few studies have focused on the analysis of airports in Iran. Researchers have evaluated the efficiency of airports using cross sectional analysis, but there has not been any study that evaluate the performance of the Iranian airports using Dynamic analysis. It is clear that for comprehensive performance assessment, cross sectional analysis is necessary, but this type of analysis does not cover all aspects of performance and Dynamic analysis should be used to achieve comprehensive results. This paper analyses efficiency of airports in 2013 through integrated DEA/AHP approach and Airports are ranked according to the results of this model. Then, the productivities of Iranian airports over the period of 2008–2013 are analyzed using the Malmquist index. The main objective of this, is to propose dynamic analysis for airport’s performance. The findings indicate that Ahvaz, Mehrabad and Mashad airport had higher performance Score Than other in 2013, and Abadan airport had the worst performance. But ] in terms of productivity growth, airports in Surrey, Yazd and Abadan, have experienced the greatest improvement in their performance during 2008 to 2013. Also, in terms of the Malmquist index, the average rate of productivity showed a slight improvement in this period of time, and the core engine of this was increase in technological efficiency.