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مرکز اطلاعات علمی SID1
اسکوپوس
دانشگاه غیر انتفاعی مهر اروند
ریسرچگیت
strs
Author(s): 

JOSHI M.V. | AGRAWAL R.C. | KUMAR V.

Issue Info: 
  • Year: 

    2001
  • Volume: 

    -
  • Issue: 

    -
  • Pages: 

    91-102
Measures: 
  • Citations: 

    440
  • Views: 

    11620
  • Downloads: 

    25177
Keywords: 
Abstract: 

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Issue Info: 
  • Year: 

    2015
  • Volume: 

    45
  • Issue: 

    2
  • Pages: 

    161-167
Measures: 
  • Citations: 

    1
  • Views: 

    1153
  • Downloads: 

    361
Abstract: 

The basis of the Ohmic Heating process is the transmission of alternating electric current through multi-phase solutions that is followed by heat generation due to particle resistance to the transmitted electric current. Throughout the present study, simultaneous transfer of heat and electricity was modeled in a Two-phase system of solid-liquid food to investigate the critical factors affecting the process. A three-dimensional simulation was employed in the modeling to investigate the effect of particle distribution, salt diffusion as well as electrical conductivity. The results revealed that there existed a good agreement between the results of the modeling with the experimental results. It was also revealed that with increase in the concentration of salts and electrical conductivity, heating rate increased. In total, it can be concluded that heat and electricity diffusion throughout the product is faster than that in conventional heating methods and proceed similarly and almost with equal speed in both liquid and solid phases.

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Author(s): 

ASADOLLAHI M.

Issue Info: 
  • Year: 

    2019
  • Volume: 

    16
  • Issue: 

    3
  • Pages: 

    84-92
Measures: 
  • Citations: 

    0
  • Views: 

    60807
  • Downloads: 

    205115
Abstract: 

Although Two-phase flow is frequently encountered in various locations of the process plants, there is no a generally accepted and verified twophase flow model that may be used to size lines for such conditions. An obvious example is condensate water return lines. The API method used in this study is based on the homogeneous equilibrium flow assumption, that is, equal velocity and equal temperature in both liquid and vapor phases. Moreover, DIERS method was used to verify and clarify the HEM approach to calculating the pressure drop in twophase regimes. The objective of this study is to introduce a solution for process lines design during different flashing scenarios. Applying API method, this study can find the Two-phase line pressure drop and upstream pressure, while, by using DIERS method, one could realize that for a specified length of pipe how much Two-phase flow could pass through when the pressure drop is just the same as that in the API model.

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گارگاه ها آموزشی
Journal: 

JOURNAL OF HYDRAULICS

Issue Info: 
  • Year: 

    2020
  • Volume: 

    15
  • Issue: 

    1
  • Pages: 

    1-11
Measures: 
  • Citations: 

    0
  • Views: 

    103
  • Downloads: 

    121
Abstract: 

Introduction: 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 studied 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. flow-3D numerical model, version 10, is used to study the flow field around the vanes. Methodology: 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 recirculating 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 study vane-induced velocity field, 4×4 cm 2 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. Results and discussion: On the high-pressure side of the vanes, vertical velocity components were upward (positive) and on the low-pressure side were downward (negative). Therefore, a clockwise secondary circulation was generated at downstream of the vanes. Downward velocity components at leading edge of primary rectangular vane (vane V0) were obvious. By cutting parts of leading edge out of vane V0 for tapered vanes V1 and V2, the magnitude of negative w-velocity components was respectively reduced by 40% and 69%. By increasing the taper angle for vanes V3, V4 and V5, downward velocity components were diminished, effectively. Moment of momentum (MOM) quantity was used in order to evaluate strength of vaneinduced circulation. MOM values were 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) were used. Therefore, this quantity is a useful criterion for evaluation of the performance and efficiency of the submerged vanes. Conclusion: 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 showed that the performance of tapered vanes (V1 to V5), relative to the rectangular vane, (at distance of 2Ho) is respectively reduced by 5. 8%, 7. 3%, 17. 8%, 33% and 42. 6%; at distance of 4Ho the amount of reduction respectively is 7. 4%, 11. 9%, 17%, 25. 5% and 34. 3%. On the contrary, the efficiency of the tapered vanes increased. The amount of increasing at distance of 2Ho from the center of vanes V1 to V5 respectively is 3. 2%, 9%, 11%, 14% and 14. 8% and at distance of 4Ho respectively is 1. 4%, 3. 6%, 12. 1%, 26. 7% and 31. 3%. Therefore, if tapered vanes are used to reduce the local scour, big values for the distance between the vanes arrays (δ s), according to the design criteria, are not recommended.

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Issue Info: 
  • Year: 

    2017
  • Volume: 

    8
  • Issue: 

    1
  • Pages: 

    1-8
Measures: 
  • Citations: 

    0
  • Views: 

    91887
  • Downloads: 

    36708
Abstract: 

In this study, the thermal characteristics of an individual room in a building are measured by making use of environmental data. Subsequently, the target heat capacity consumption by the air-conditioning system can be calculated and controlled, depending on the environmental target. By establishing the relationship between a change in the room environment (environmental evaluation index) and the heat capacity consumption of the room (the amount of change of the enthalpy) by the air conditioning, we can calculate the target heat capacity consumption feasible as an environmental target. Relying on an environmental target in calculating the target heat capacity consumption enables setting suitable targets to avert the risk of heat exhaustion or even heatstroke to the residents of the building. In addition, a useful room heat capacity model is suggested that includes a management method using a heat capacity consumption target, with an administration table for evaluating the target.

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Issue Info: 
  • Year: 

    1392
  • Volume: 

    31
  • Issue: 

    4 (پی در پی 100)
  • Pages: 

    206-212
Measures: 
  • Citations: 

    0
  • Views: 

    305
  • Downloads: 

    135
Abstract: 

سابقه و هدف: شناخت مواد ترمیمی نظیر کامپوزیت های flow able که بهترین خواص فیزیکی از جمله ریزسختی مناسب را دارا بوده، تحت تاثیر عوامل محیطی، مقاومت کافی را داشته باشند، دغدغه اصلی بسیاری از دندانپزشکان در این زمینه است. یکی از کاربردهای کامپوزیت فلو، درمان فیشورسیلنت و ترمیم محافظه کارانه رزینی می باشد که درمانی رایج در دندانپزشکی کودکان است. ژل موضعی (Acidulated Phosphor Fluoride (APF می تواند سبب تخریب سطحی، کاهش وزن و کاهش مقاومت به سایش در کامپوزیت ها شود. هدف از این تحقیق بررسی تاثیر ژل APF بر میزان ریزسختی کامپوزیت های فلو بود.مواد و روشها: در تحقیق تجربی- آزمایشگاهی حاضر جامعه مورد بررسی شامل 60 نمونه کامپوزیت فلو با نام های Tetric N-flow (Ivoclar-Vivadent)، Permaflo (Ultradent) و Denfil (Vericom) بود. نمونه ها به صورت دیسک هایی با ضخامت 2 میلی متر و قطر 6 میلی متر تهیه و به مدت یک هفته در بزاق مصنوعی در دمای اتاق قرار گرفتند. سپس 20 نمونه هر ماده به طور تصادفی به دو گروه ده تایی شاهد و آزمون تقسیم گردیدند. اندازه گیری سختی باروش Vicker’s انجام گرفت. در گروه شاهد، در هر دیسک سه بار indentation روی یک دایره با فاصله حداقل یک میلی متر از هم و از لبه نمونه ها انجام گرفت و میانگین محاسبه گردید. در آخر برای همه ارزیابی ها یک میانگین گرفته شد. سپس نمونه های آزمون به مدت 4 دقیقه در معرض ژل (1.23%) APF سلطان قرار گرفتند و با آب شستشو و با هوا خشک گردیدند و مجدادا میزان ریزسختی آنها طبق روش بالا اندازه گیری شد. جهت مقایسه اثر ژل APF و نوع کامپوزیت بر روی ریزسختی انواع کامپوزیت فلو از آزمون 2- WAY ANOVA استفاده گردید.یافته ها: نتایج نشان دادند که میزان ریزسختی کامپوزیت های فلوی Tetric N-flow، Permaflo و Denfil قبل از بکارگیری ژل فلوراید APF به ترتیب 16.5±1.32، 37.36±2.13، 20.39±0.52 و پس از بکارگیری فلوراید به ترتیب به 16.46±2.20، 35.06±2.43 و 19.13±2.20 رسید که تفاوت قبل و بعد برای هر ماده بی معنی (P=0.193) ولی بین مواد مختلف معنی دار بود (P<0.001). نتیجه گیری: قرارگیری کامپوزیت های فلوی Tetric N-flow، Permaflo و Denfil در معرض ژل APF به مدت 4 دقیقه، تاثیری بر میزان ریزسختی آنها ندارد.

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strs
Author(s): 

AMIN NAYERI M. | MOSLEHI G.

Issue Info: 
  • Year: 

    2001
  • Volume: 

    12
  • Issue: 

    3
  • Pages: 

    191-209
Measures: 
  • Citations: 

    0
  • Views: 

    1927
  • Downloads: 

    129
Keywords: 
Abstract: 

The problem of determining the sequence of a set of jobs with the objective function (OF) for minimizing the maximum earliness and tardiness, is studied. Since this OF is trying to minimizing and diminish the values of earliness and tardiness, it corresponds to different production systems, such as jIT. This OF is studied in problems associated with m machine and n jobs in flow Shop case (n/m/P/Etmax).Several methods have developed for solving flow shop problems. Two quick heuristic methods, called HI and H2, with the aim of finding proper solutions in short time, are suggested. The branch and bound (BB) optimal method for solving n/rn/P/ETmax problems is applied. Offering fair upper and lower bounds results in obtaining optimal solutions in many problems. 400 n/rn/P/ETmax problems of small, medium and large sizes are randomly generated.For 83% of problems, optimal solutions are obtained, by BB method. The associated ranges for these problems are 4 to 75 machines and 4 to 50 jobs.

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Author(s): 

MEHRAVANI H.

Issue Info: 
  • Year: 

    2019
  • Volume: 

    32
  • Issue: 

    1 (122)
  • Pages: 

    17-23
Measures: 
  • Citations: 

    0
  • Views: 

    465
  • Downloads: 

    272
Abstract: 

Foot and Mouth Disease (FMD) vaccine is one of the inactivated vaccines and its potency depends on the antigen quality, antigen concentration per dose, and adjuvant. In this study to introduce the better antigen concentration method, both active and inactive of three serotypes O, A05, and Asia of FMD virus were used. Each of the virus type was cultivated in BHK21 cell culture and half of each viral suspension inactivated by ethylene imine. The physical method; ultra filtration (cross flow system) and the chemical method; treatment with poly ethylen glycole (PEG6000) were used for virus concentration following safety assay. The quantity of virus recovery was evaluated by virus adsorption by aluminum hydroxide gel, complement fixation, ELISA, TCID50 titration, and sucrose concentration on the collected samples. The results indicate that the concentration rate did not affect virus adoption by aluminum hydroxide gel and the quantity of virus recovery using ultra filtration was higher than PEG precipitation.

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Author(s): 

KAMANBEDAST A. | FARAJ POOR B.

Issue Info: 
  • Year: 

    2011
  • Volume: 

    1
  • Issue: 

    1
  • Pages: 

    75-85
Measures: 
  • Citations: 

    0
  • Views: 

    1142
  • Downloads: 

    454
Abstract: 

Bottom intake is an intake structure which can be considered as an alternative for regular intakes in mountain streams Water in in taking from river are very vast and complicated issues, each project has special characteristics which should be considered. Water intake from river is generally based on Pump and gravity method. The gravity method is more useful and common because of continuity and no need spare energy rather than pump method. The different methods are possible at gravity methods these methods are divided in to three categorize: side in take, front structure and bottom structure.According to the recent experiences at countries for maintain region, when longitude slope is more than 1% and 75% of bed load is particles with size more than of mm (D50>6mm) bottom in take are recommended generally. Hydraulic analyses of this type of structure are not studied numerically. In other side of Cain, building and studying physical model of this type of structure are very difficult tasks. In this research, flow simulations of bottom in take are done using the flow 3D software. As a result, it's conducted that best Slope for intake net is degree and when opening area. Increased directed discharge increase directly. Finally it's driven that when Froude number increased opening percentage, it May caused reduction of flow coefficient.

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Author(s): 

GOLSHANI ALIASGHAR

Issue Info: 
  • Year: 

    2011
  • Volume: 

    7
  • Issue: 

    13
  • Pages: 

    67-74
Measures: 
  • Citations: 

    0
  • Views: 

    1020
  • Downloads: 

    321
Abstract: 

The goal of this study was to simulate the hydrodynamics induced by con-current wind and tide loading in the southern part of the Persian Gulf. The model was calibrated with a 28 day lunar cycle, in which both neap and spring tide were modeled. The model boundaries were forced using tidal water levels obtained from the United Hydrographic Tide Tables. Wind data extracted from PERGOS database was used as input to the model. Current data recorded at Ghasha buoy, as well as current and water level data from PERGOS database were used for calibration of the model. The error in water level prediction is typically less than 25% of tidal range. Currents were also predicted with accuracy of 0.1 m/s (95% of time). Model results are insensitive to variations of calibration parameters over the recommended range, which demonstrates that the model is robust and can be used with confidence.

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