بررسی کاهش آلودگی صوتی مسیرهای تخلیه سیال به اتمسفر با استفاده از سایلنسرهای ونت به روش عددی (original) (raw)
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2008
The effect of removal of smear layer has already been a subject in many investigations, and has been a matter of controversy. Of course there is no doubt that sealer penetration would be facilitated when smear layer removed. The aim of this study was evaluation of the relationship between sealer penetration and apical microleakage after usage of MTAD. Materials & Methods: In this invitro study, 135 human single root extracted teeth were selected. The teeth were divided into three groups (40 samples in each) as experimental groups as follow: Group 1: Serum was used for irrigation (with the smear layer). Group 2: EDTA 17% was used for irrigation (removal of the smear layer). Group 3: MTAD was used for irrigation (removal of the smear layer) and 15 teeth were considered as the control. The teeth in each group were divided into two subgroups (20 teeth) to be filled either with AH Plus or Dorifill sealer. Sixty teeth were selected for dye penetration with methylene blue and statistically analysed using One-Way and Two-Way ANOVA. In the other 60 teeth, sealer penetration was evaluated using SEM. The data were statistically analysed using Kruskal-Wallis and Mann-Whitney tests. The end relationship between dye penetration and sealer penetration was evaluated by spearman correlation test. Results: There was no significant difference between the three types of irrigants. There was a significant difference between the two sealers. AH plus revealed less dye penetration. Minimum dye penetration was observed in MTAD group with AH Plus and maximum dye penetration was observed in Serum group with Dorifill. Sealer penetration in MTAD and EDTA groups were better than Serum group. AH Plus was better than Dorifill. The correlation between sealer penetration in dentinal tubules and dye penetration wasn't statistically significant. Conclusion: Type of irrigant didn't affect apical microleakage but type of sealer affected microleakage. AH Plus proved to be better. AH Plus showed greater sealer penetration. Greater sealer penetration does not necessarily reduce apical microleakage.
مهندسی مکانیک و ارتعاشات, 2014
The purpose of this research was to develop a thermodynamic model for engine via changing the form of regenerator. In conventional betatype Stirling the working fluid passes between the compression and expansion space via the bypass of the main cylinder. In the present study a new form of regenerator was proposed for the beta-type Stirling engine. In this new form successive homogeneous layers of sguare wire meshes filled the space of displacer piston so that the displacer piston took the role of regenerator and displacer simultaneously. To this end modeling was done using MATLAB software and the obtained results were compared with the published values.
تعیین ضرایب معادله آنگستروم و توسعه یک معادله رگرسیونی برآورد تابش خورشیدی (مطالعه موردی:منطقه مشهد)
2009
Solar radiation, nowadays has a lot of application in different fields of agriculture, irrigation, and hydrology engineering and due to these various applications, different models has been proposed for it’s estimation. Angstrom-Prescott equation is one of the most important well known models for solar radiation estimation. This equation has empirically coefficient that various for each location. In this paper, the data gathered in Mashhad Synoptic station during 1378 and 1380, Angstrom-Prescott coefficient has been identified according to the ratio of actual sunshine hours (n) to the maximum sunshine hours (N). Also a Regression local equation has been proposed considering several meteorology parameters including daily gathered data of saturation vapor pressure deficit, precipitation, air temperature mean, relative humidity percentage and n/N. Finally the proposed model has been evaluated according to the independent measured data during 1381 to 1382. The statistical analysis of th...
Journal of Health, 2019
Background & objectives: Modeling with software is a fast way to predict the extent of material release range and simulate its consequences. Due the arrival of the large number of dangerous goods, including styrene, from the petrochemical industries to the port of Imam Khomeini, it is necessary to evaluate the consequences and potential damages of this material.This study was conducted in 2014 in Imam Khomeini Port Container Terminal with the aim of predicting and estimating the possible human and environmental consequences of the release of this hazardous material during transportation process. Methods: In this study, with the use of PHAST and ALOHA softwares, the effect of toxicity of styrene was studied as a dangerous good entered into the container terminal. The analysis was performed by identifying the range of areas with highest adverse effects. Results: According to the results, the extent of pollution coverage (the forbidden region) was at least in a radius of 67 meters and the best place for placement of support groups was in a radius of 329 meters of dangerous goods area. The study also showed that based on the coverage of the risk range in these modeling, ALOHA software had a high environmental sensitivity, because the amount of LOCs considered in the consequence of the explosion was lower and it considered more danger zones. Finally, management measures were pointed to prevent or reduce the potential consequences of hazardous goods storage sites and warehouses in the study area. Conclusion: The environmental outcomes of dangerous goods containers in Imam Khomeini port are likely to be probable. So that the release consequences of these materials can cause a lot of environmental damage and accidents. Therefore, it can be said that modeling using software in this study played a key role in managing the area of hazardous materials containers.
Stepped spillways have significant importance for their indisputable effect on energy dissipation and for compatibility with roller compact concrete method in construction. In order to design these spillways, physical models are commonly used in spite of spending great time and cost. Progress of high speed computers, however, permits to utilize computational fluid dynamic (CFD) method and therefore diminishing time and cost. In this research, some physical results are used for simulation of flow on stepped spillways, by applying FLUENT CFD package. Skimming and transitional regimes are investigated for the spillway. The simulated parameters were characteristic depth (y 90), characteristic velocity (V 90), clear water velocity and mean air concentration. Multiphase models consisting of volume of fluid (VOF), mixture and Eulerian and also turbulence models of k-ε, also coupling pressure-velocity algorithms of PISO and Simple were used both two and three dimensionally. Mixture and RNG k-ε for multiphase and turbulence models totally produced satisfactory results. The results were good for evaluation of the hydraulic parameters considering air bubble entrainment in skimming regime and relatively poor for transitional regime.
2019
Nowadays, simulation of viscoelastic flows at high Weissenberg numbers is one of the most obstacles and important issues for rheologists to observe the rheological properties at sufficiently high weissenberg number. It is well known that the conformation tensor should, in principle, remain symmetric positive definite (SPD) as it evolves in time. In fact, this property is crucial for the well-posedness of its evolution equation. In practice, this property is violated in many numerical simulations. Most likely, this is caused by the accumulation of spatial discretization errors that arise from numerical integration of the governing equations. In this research, we apply a mathematical transformation, the so-called hyperbolic tangent, on the conformation tensor to bound the eigenvalues and prevent the generation of negative spurious eigenvalues during simulations. The flow of FENE-P fluid through a 2D channel is selected as the test case. Discrete solutions are obtained by spectral/hp e...
Journal of Rafsanjan University of Medical Sciences, 2018
دشاب یم . رد تیلاعف ياه یتعنص ، کینکت ياه یبایزرا و تیریدم کسیر زا هدافتسا قیرط زا درکیور يریگشیپ و اب فده دوبهب ینمیا يارب شهاک ثداوح هب راک هتفرگ یم کسیر یسررب فده اب هعلاطم نیا .دوش تسیز ياه نزاخم رد یتشادهب و ینمیا ،یطیحم هریخذ س .دش ماجنا نایسراپ زاگ شیلااپ تکرش يزاگ تاناعیم يزا شور و داوم :اه لاس رد یفیصوت هعلاطم نیا 1395 تسیز تارطاخم ییاسانش .تفریذپ ماجنا و ینمیا ،یطیحم یتشادهب تیلاعف و تاسیسات زا لصاح وم یناسنا ياه هریخذ نزاخم رد دوج تاناعیم يزاس یفلد کینکت زا هدافتسا اب يزاگ و ماجنا کسیر سپس شور زا هدافتسا اب هدش ییاسانش ياه AHP ) Analytical Hierarchy Process ( هلسلس لیلحت و هیزجت ، یبتارم (FMEA) و هیزجت و احلیلحت لا ت تسکش یسررب آ و اث ر نآ تیولوا و یبایزرا دروم .تفرگ رارق يدنب هتفای اه : هعلاطم نیا رد 17 هک دش ییاسانش کسیر 12 سیر تسیز هب طوبرم نآ ک و یطیحم 5 و ینمیا هب طوبرم کسیر یتشادهب دوب هب جیاتن ساسا رب . تسیز کسیر نازیم نیرتلااب ،هدمآ تسد یطیحم ینمیا و ،بیترت هب نزاخم رد یتشادهب شتآ زوس ددع اب يدمع و یتسیرورت لماوع رثا رب ي RPN ) Priority Nnmber Risk ( ، 824 / 1 یح ...