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Issue Info: 
  • Year: 

    1382
  • Volume: 

    5
Measures: 
  • Views: 

    592
  • Downloads: 

    0
Abstract: 

در این مقاله روشهای مختلف نگهداری موتورهای دیزل به کمک روش (condition Monitoring) بررسی شده است. روشهای بکار رفته برای نگهداری پیش بینانه موتورهای دیزل شامل آنتالیز ارتعاشات، آنالیز راندمان، آکوستیک، ترموگرافی، آنالیز روغن و بررسی سیستم خنک کننده می باشد. هر یک از این روشها طی مثالی بررسی شده و نحوه استفاده از آن تشریح شده است. نتایج این بررسی نشان می دهد که استفاده به موقع از هر یک از تکنیک های فوق می تواند سبب بالا رفتن قابلیت، اطمینان و نیز کاهش هزینه های نگهداری و تعمیرات گردد.

Yearly Impact:   مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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Author(s): 

Abbasi Sarallah | JOODAKI ALI

Issue Info: 
  • Year: 

    2020
  • Volume: 

    10
  • Issue: 

    1
  • Pages: 

    271-279
Measures: 
  • Citations: 

    0
  • Views: 

    93
  • Downloads: 

    112
Abstract: 

In this paper, a parametric study of compressor performances is performed by the streamline curvature method. Effects of three input parameters in the Design process, e. g., number of blades, distribution of blade thickness, and blade sweep angels, on the main objective parameters in the aerodynamic Design, e. g., velocity distribution, efficiency, and pressure ratio, are investigated in the parametric study. Initially, a certain two-stage axial compressor is Designed by the streamline curvature method. Validation of the results is confirmed by comparing the obtained results with the experimental ones. Regarding various values for the aforementioned input parameters, the first stage of the axial compressor is reDesigned, and the output parameter is established. Therefore, the sensitivity of the Design results to each of the aforementioned parameters is recognized. Results show that increasing the blades sweep angle causes the flow behavior, such as efficiency and pressure ratio in the axial fan, to improve while reducing it provides a completely contrary result. Also, reducing the rotors blades number leads to an increase in the pressure ratio and efficiency while its increase causes a contrary result. It is concluded that a reduction in the number of the blades has a stronger effect on the performance parameters than when it increases. The results also show that the effect of the thickness in the hub is greater than the thickness of the tip, and its increase leads to reduce both efficiency and pressure ratio.

Yearly Impact: مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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Issue Info: 
  • Year: 

    1387
  • Volume: 

    1
Measures: 
  • Views: 

    413
  • Downloads: 

    0
Abstract: 

با توجه به این مساله که دستگاه های موجود در سطح پتروشیمی بندر امام (و برخی از مجتمع های مشابه) از قدمت زیادی برخورد دارند (بعضا حدود 30 سال) و عموما احتمال زیادی برای خرابی ناگهانی و عدم اطلاع سریع از خرابی های موجود وجود دارد لذا با توجه به طرح ذیل که برای اولین بار در سطح پتروشیمی بندر امام و به خاطر شرایط خاص این مجتمع مطرح شده است، کاربران این امکان را پیدا خواهند کرد تا دستگاه های موجود را بدون حضور فیزیکی کنترل و تعیین وضعیت و یا اصطلاحا Control condition Monitoring کرده و در صورتیکه در حال مشاهده دستگاه condition Monitoring به وسیله کامپیوتر نباشند دستگاه کنترلی به تنهایی قادر به کنترل و در صورت بروز خطا قادر به اعلام آلارم و قطع برق و جلوگیری از حرکت قطعات قسمت های مهم دستگاه برای جلوگیری از خرابی های بیشتر است. در نهایت مزایای این سیستم ما را بر این داشت تا بررسی های دقیقتری در این زمینه انجام داده و در نهایت کار بررسی، طراحی، و در صورت تصویب نهایی نصب و راه اندازی سیستم آزمایشی را به انجام رسانیم.

Yearly Impact:   مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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Issue Info: 
  • Year: 

    2022
  • Volume: 

    52
  • Issue: 

    3
  • Pages: 

    189-194
Measures: 
  • Citations: 

    1
  • Views: 

    127
  • Downloads: 

    38
Abstract: 

Intracytoplasmic sperm injection (ICSI) is one of the most successful techniques of Assisted Reproductive Technology (ART) and is mostly in use for the treatment of infertility with male factors. In this method, before injecting sperm into the intracytoplasmic of the oocyte, cumulus cells around the oocyte must be stripped to facilitate the injection process. To achieve this, both enzymatic and mechanical methods are used in embryological laboratories for denudation, which has major deficiencies, including the possibility of damaging the oocyte prior to the injection process. In this research, a microfluidic-based device is introduced for the separation of cumulus cells around the oocyte with minimum manual operations. The results prove high efficiency, and non-destructive denudation of the oocyte with the reduced amount of culture medium leads to the low-cost preparation process of oocytes. The process can also be integrated with ICSI chips under development and will be reported shortly.

Yearly Impact: مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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Journal: 

GEOGRAPHICAL DATA

Issue Info: 
  • Year: 

    2017
  • Volume: 

    26
  • Issue: 

    101
  • Pages: 

    61-71
Measures: 
  • Citations: 

    0
  • Views: 

    861
  • Downloads: 

    0
Abstract: 

The ubiquity of mobile devices, such as smart phones and tablets, has contributed to the development of pervasive systems, including navigation and health systems. The main characteristicsof pervasive systems are the necessity of dynamic reconfiguration and proper adaption to the continuous changes in different contexts. The existence of dynamic capabilities has been considered in the Design and implements of a context aware system, including context acquisition, context understanding and computing, decision making, and context presentation. Context acquisition: This domain of research focuses on using personal sensing devices which measure various parameters by means of portable devices and save them on the external/internal database for further processing. The aim of researches is collecting, sharing, and/or reusing data in other applications or through a web interface. Context understanding and computing: The most works are in the field of context monitoring, data management, understanding or computing. The ability to automated context reasoning about various types of contexts and their properties are considered using various context models and algorithms. Most applications are customized for a specific case such as air pollution, tourist, navigation, and health-care. Context presentation: This category of research has commonly focused on context-aware application adaptation. The adaption happens between the real world, the map and user’ s location and orientation. A number of studies have been carried out in the field of tourist guides or navigation adapting the presentation style to the changing requirements of the user. Most studies in ubiquitous health care have only been carried out in a small number of areas and using external portable sensors and developing applications on mobile phones. A major problem with this kind of applications is collecting and sharing data, monitoring, or reasoning without having an active role in decision making in different environmental conditions. Using external tools such as portable devices is costly and limits using the systems. This paper has focused on Design and implementation of a context aware ubiquitous system which has been customized for severe environmental conditions (in particular, air pollution). Air pollution is a spatio-temporal phenomenon and it causes changes in health conditions and it increases mortality. Eclipse Kepler software, java, PHP programming language and MySQL and SQLit database and also Google Maps API was used in this research. The proposed system Design approach is based on distributed architecture in the portion of data collection and processing. Data collecting is done by means of software and hardware sensors. The context aware system is able to automatically identify the user’ s context and represent required data and information after computing and reasoning. Contexts based on their impact on the decision-making process can be divided into two categories: passive and active contents. We used an active context in the research such as time, location, traffic, direction, air pollution. Collecting required data is done automatically with high speed and accuracy, and data plays an active role in decision making. In the system architecture, servers were embedded to enter data automatically and only data relating to health conditions is entered manually. Processing environment was divided into two parts, in case of abounding calculations, processing is transferred to the server so that only light processing is performed on the client. At every stage of the process, the user interface provided outputs in the form of recommendations and notifications. The system represents user-friendly environment. Context information can be posted on the process server and retrieved from the history. The proposed system can become an important tool to enable patients to be aware of air pollution conditions, not only to be applied in managing and monitoring their health information, but also in decision making, finding the best solution in severe environment, sharing data and communicating with family and doctor. The application represents suitable solution for solving the shortest path problem according to spatial-temporal and traffic condition. In fact, the path with the lowest level of air pollution is chosen as the best path. The system indirectly encourages greater use of the ubiquitous health system and motivates patients to acquire an active role in their health management and helps them to improve their health condition. The information collected and posted on the server can be reused in professional station and it presents useful information to health experts. We broadly concern about patients’ privacy in the Design of the system.

Yearly Impact: مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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Author(s): 

NASEH HASSAN | ALIPOUR ALI

Issue Info: 
  • Year: 

    2018
  • Volume: 

    18
  • Issue: 

    2
  • Pages: 

    84-94
Measures: 
  • Citations: 

    0
  • Views: 

    722
  • Downloads: 

    0
Abstract: 

The purpose of this article is to system Design methodology of Propellant Management Device (PMD) for hydrazine fuel tank which used in low (zero) gravity conditions. To this end, the suggestion system Design flowchart has three main steps that concluded: step one, Tank Design and modeling; step two, PMD Design and modeling and step three, stored fuel treatment simulation and analysis. In the Design flowchart has performed the result of each step based on mission inputs. Therefore, rejected results in each step led to vary the related parameters. Thus Solid Works software is used to primary PMD and tank modeling. Then, numerical simulation is performed to consider PMD's performance and to illustrate the capillary phenomenon for continues fuel transferring in zero-gravity conditions. Also, numerical methods are used to analysis of the tank and the fuel behavior inside the tank with PMD to optimize system Design parameters. Hence, Ansys software used to finalize modelling, analysis, meshing and consideration of fuel behavior in PMD by utilizing the Volume Of Fluid (VOF) method. The optimal system parameters related to specifications of PMD with maHimum performance of mass and volume flow rates in zero gravity. In conclusion, by comparing the results (PMD performance) with experimental and existing results will be verified.

Yearly Impact: مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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Issue Info: 
  • Year: 

    2014
  • Volume: 

    11
Measures: 
  • Views: 

    139
  • Downloads: 

    49
Abstract: 

INTRODUCTION: SUBSEA PIPELINES WHICH CROSS OVER IRREGULAR SEABED PROFILE CAN CAUSE FREE SPAN OVER DEPRESSIONS. SO, SOME IMPERFECTIONS CAN BE EMERGED ALONG THE PIPELINE ROUT BECAUSE OF FREE SPANS AND THESE DEFORMATIONS ARE VITAL FACTOR FOR AMENDING PIPELINE BEHAVIOR SUBJECTED TO AXIAL COMPRESSIVE LOAD AND PIPE COMBINED STRESSES...

Yearly Impact:   مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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Issue Info: 
  • Year: 

    2022
  • Volume: 

    11
  • Issue: 

    1
  • Pages: 

    41-48
Measures: 
  • Citations: 

    0
  • Views: 

    24
  • Downloads: 

    0
Keywords: 
Abstract: 

One of the issues of reliable performance in the power grid is the existence of electromechanical oscillations between interconnected generators. The number of generators participating in each electromechanical oscillation mode and the frequency oscillation depends on the structure and function of the power grid. In this paper, to improve the transient nature of the network and damping electromechanical fluctuations, a decentralized robust adaptive control method based on dynamic programming has been used to Design a stabilizing power system and a complementary static var compensator (SVC) controller. By applying a single line to ground fault in the network, the robustness of the Designed control systems is demonstrated. Also, the simulation results of the method used in this paper are compared with controllers whose parameters are adjusted using the PSO algorithm. The simulation results show the superiority of the decentralized robust adaptive control method based on dynamic programming for the stabilizing Design of the power system and the complementary SVC controller. The performance of the control method is tested using the IEEE 16-machine, 68-bus, 5-area is verified with time domain simulation.

Yearly Impact: مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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Author(s): 

Heidarzadeh Ali | Modares Sanavi Seyed Ali Mohamad | Mokhtassi-Bidgoli Ali

Issue Info: 
  • Year: 

    2021
  • Volume: 

    52
  • Issue: 

    2
  • Pages: 

    15-27
Measures: 
  • Citations: 

    0
  • Views: 

    141
  • Downloads: 

    12
Abstract: 

To investigate the effects of fertilizer regimes on quantitative and qualitative traits of Dracocephalum kotschyi Boiss, a field experiment at three replications with the Split Plate arrangement in a completely randomized block Design was conducted in the Research Field of Tarbiat Modares University during the 2017-18 growing season.Water deficit stress (irrigation after discharging 20 (optimal irrigation), 40 (mild water deficit stress), 60 (moderate water deficit stress) and 80% (severe water deficit stress) of water used (available water)) in the main plot and fertilizer regime (urea, nitroxin, vermicompost, azocompost and no fertilizer) in the subplot were studied. The results showed that the highest leaf fresh weight (1797 kg ha-1) and total biomass (2957 kg ha-1) were obtained by application of urea in mild water deficit stress condition and the highest dry matter digestibility percentage was observed in azocompost treatment in moderate water deficit stress condition (57.8%). The highest crude protein was produced in severe water deficit stress condition (19.72%) and moderate water deficit stress (18.4%), respectively.. The highest percentage of water soluble carbohydrate and neutral detergent fiber were obtained from no fertilizer in moderate water deficit stress (22.06%) and application of urea in severe water deficit stress conditions, respectively. Mild water deficit stress application to produce high biomass is recommended for Dracocephalum kotschyi Boiss. According to the results, application of urea in mild water deficit stress was selected as the best treatment to produce forage 32% more than control.

Yearly Impact: مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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Issue Info: 
  • Year: 

    2022
  • Volume: 

    52
  • Issue: 

    1
  • Pages: 

    43-49
Measures: 
  • Citations: 

    0
  • Views: 

    118
  • Downloads: 

    20
Abstract: 

Monitoring and evaluation of transformers are essential to prevent their insulation failure. In this paper, the use of 2-furan-carboxaldehyde (2-FAL) and methanol (MeOH) concentrations as the main products of paper insulation degradation, and insulation condition markers, has been studied. In order to study the degradation process and production of degradation products, the thermal aging process of the transformer insulation system was implemented in laboratory conditions. The results of laboratory studies show that in the early stages of degradation the amount of MeOH is significant compared to 2-FAL. Also, the estimation of the degree of polymerization (DP) in the early stages of degradation (DP>800) through MeOH concentration and with decreasing DP (DP <800) through 2-FAL concentration is closer to the real value. The results of studies performed on 35 distribution transformers confirm the production of significant amounts of MeOH in the early stages of degradation. Also, the estimated DP values for the studied transformers were obtained through 2-FAL and MeOH concentration. The results show that estimating the amount of DP through MeOH concentration is associated with a probability of error of about 9% compared to estimating DP through 2-FAL concentration.

Yearly Impact: مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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