فیلترها/جستجو در نتایج    

فیلترها

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نویسندگان: 

GHORBANPOUR ARANI A. | KOLAHCHI R.

اطلاعات دوره: 
  • سال: 

    2012
  • دوره: 

    4
  • شماره: 

    2
  • صفحات: 

    144-158
تعامل: 
  • استنادات: 

    0
  • بازدید: 

    324
  • دانلود: 

    0
چکیده: 

In this study, free vibration of a FOAM-core orthotropic SMART composite cylindrical shell (SCCS) filled with a non-viscous compressible fluid, subjected to combined electro-thermo-mechanical loads is investigated. Piezoelectric polymeric cylindrical shell, is made from polyvinylidene fluoride (PVDF) and reinforced by armchair double walled boron nitride nanotubes (DWBNNTs). Characteristics of the equivalent composite are determined using micro-electro-mechanical models. The poly ethylene (PE) FOAM-core is modeled based on Winkler and Pasternak foundations. Employing the charge equation for coupling electrical and mechanical fields, the problem is turned into an eigenvalue one, for which analytical frequency equations are derived considering free electrical and simply supported mechanical boundary conditions at circular surfaces at either ends of the cylindrical shell. The influence of electric potential generated, filled-fluid, orientation angle of DWBNNTs, FOAM-core and a few other parameters on the resonance frequency of SCCS are investigated. Results show that SCCS and consequently the generated Φ improve sensor and actuator applications in several process industries, because it not only increases the vibration frequency, but also extends economic viability of the SMART structure.

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نویسندگان: 

SEYED KANANI ALI REZA | OHADI ABDOLREZA

اطلاعات دوره: 
  • سال: 

    2015
  • دوره: 

    1
  • شماره: 

    1
  • صفحات: 

    1-9
تعامل: 
  • استنادات: 

    0
  • بازدید: 

    239
  • دانلود: 

    0
چکیده: 

The aim of this paper is robust identification of SMART FOAM, as an electroacoustic transducer, considering un modelled dynamics due to nonlinearities in behaviour at low frequencies and measurement noise at high frequencies as existent uncertainties. Set membership estimation combined with model error modelling technique is used where the approach is based on worst case scenario with unknown but bounded uncertainties. The outcome is a robust identified model which consists of a nominal model with its uncertainty bounds that fits exactly the H∞ robust control scheme which has been utilized in active noise control in recent years. While the nominal model has the desired physical characteristics as cut-off frequency and the anticipated slope and flatness before and after this frequency, respectively, it is maintained in the acceptably tight uncertainty upper and lower limits, thus validating the identification procedure. Looseness and tightness of uncertainty strip has also been discussed regarding nonlinearities and measurement noise in low and high frequency regions. Meanwhile the identified nominal model can also be utilized in non-robust noise control methods due to its lower order, reflecting the advantage of the applied identification approach.

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اطلاعات دوره: 
  • سال: 

    1395
  • دوره: 

    5
تعامل: 
  • بازدید: 

    1597
  • دانلود: 

    729
چکیده: 

خانه هوشمند مجموعه ای از تکنولوژی ها و سرویس ها در شبکه ای خانگی برای بهبود کیفیت زندگی است. که در سال های اخیر بسیار گسترش یافته و به جزء جدایی ناپذیر تمامی ساختمان های مسکونی و غیر مسکونی تبدیل شده است. تکنولوژی که چه از نظر بهبود کیفیت زندگی و چه از نظر صرفه جویی در مصرف انرژی بسیار سودمند است...

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نویسندگان: 

, , ,

نشریه: 

اطلاعات دوره: 
  • سال: 

    1401
  • دوره: 

  • شماره: 

  • صفحات: 

    35-40
تعامل: 
  • استنادات: 

    0
  • بازدید: 

    21
  • دانلود: 

    0
کلیدواژه: 
چکیده: 

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اطلاعات دوره: 
  • سال: 

    1402
  • دوره: 

    23
  • شماره: 

    2
  • صفحات: 

    126-133
تعامل: 
  • استنادات: 

    0
  • بازدید: 

    78
  • دانلود: 

    7
چکیده: 

زمینه و هدف: شکستگی فایل یکی از نگرانی­های اصلی در درمان ریشه  دندان است که می­تواند بر نتایج آن تاثیر بگذارد. مطالعه حاضر با هدف ارزیابی میزان شکست فایل SMART Tract X3 به عنوان یک سیستم جدید، در مقایسه با سیستم فایل ها چرخشی رایج، در حین آماده سازی کانال های ریشه شبیه سازی شده انجام شد. روش­ کار: تعداد 180 بلوک رزینی با کانال هایی با انحنای شدید (45 درجه) به طور تصادفی به سه گروه مساوی (60 تایی) SMART Tract X3، ProTaper Universal  و Neoniti تقسیم شدند. از هر مجموعه فایل برای پاکسازی و شکل دهی 5 کانال استفاده شد که در مجموع از 12 مجموعه فایل برای تهیه 60 کانال در هر گروه استفاده شد. تمامی فایل­ها طبق دستورالعمل سازنده استفاده شدند. تعداد (%) شکستگی ها، محل، طول و فاصله قطعات شکسته از راس بلوک ثبت شد.  یافته ها: در مجموع 60 فایل SMART TractX3 و ProTaper Universal (5 فایل در یک مجموعه) و 36 فایل از Neoniti  (3 فایل در یک مجموعه) استفاده شد. میزان شکستگی از نظر آماری تفاوت معنی­ داری در مقایسه بین گروه­ها نشان نداد. تمام شکستگی­ها در یک سوم اپیکال کانال با میانگین طول قطعات شکسته و فاصله قطعات شکسته از راس بلوک به ترتیب 0.216±2.228 میلی متر و 0.186±0.845 میلی متر اتفاق افتاد. نتیجه گیری: بین فایل ها SMART tract X3،ProTaper Universal  و Neoniti از نظر بروز شکستگی در حین آماده سازی پنج کانال با انحنای شدید تفاوت آماری معنی داری وجود نداشت.

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نویسندگان: 

FLEMINGS M.C.

اطلاعات دوره: 
  • سال: 

    1987
  • دوره: 

    95
  • شماره: 

    -
  • صفحات: 

    665-672
تعامل: 
  • استنادات: 

    1
  • بازدید: 

    110
  • دانلود: 

    0
کلیدواژه: 
چکیده: 

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اطلاعات دوره: 
  • سال: 

    2014
  • دوره: 

    21
تعامل: 
  • بازدید: 

    196
  • دانلود: 

    0
کلیدواژه: 
چکیده: 

POLYURETHANES (PU) HAVE BEEN USED IN DIVERSE AREAS AND ARE ONE OF THE MOST IMPORTANT GROUPS OF PLASTICS BECAUSE OF THEIR VERSATILITY. FLEXIBLE PU FOAMS ARE THE MOST IMPORTANT GROUP AMONG PU SPECIALTIES. THE GOAL OF CHEMICAL RECYCLING OF FLEXIBLE FOAMS IS TO REGAIN THE POLYOLS SUITABLE FOR MANUFACTURING NEW PUR FOAM. …

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نویسندگان: 

OETJEN K. | BILKE KRAUSEA C. | MADANI M.

اطلاعات دوره: 
  • سال: 

    2014
  • دوره: 

    460
  • شماره: 

    -
  • صفحات: 

    280-285
تعامل: 
  • استنادات: 

    1
  • بازدید: 

    206
  • دانلود: 

    0
کلیدواژه: 
چکیده: 

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بازدید 206

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نشریه: 

مواد نوین

اطلاعات دوره: 
  • سال: 

    1397
  • دوره: 

    8
  • شماره: 

    3 (پیاپی 31)
  • صفحات: 

    1-15
تعامل: 
  • استنادات: 

    0
  • بازدید: 

    1706
  • دانلود: 

    418
چکیده: 

هدف از پژوهش حاضر، ارائه روش ساخت فوم سلول باز مسی با سطح ویژه بالا به روش شیمی تر است. از میان روش های مختلف تولید فوم سلول باز فلزی، روش رسوب دهی الکتریکی به دلیل تمیز و ارزان بودن نسبت به روش های دیگر انتخاب شد. در این روش از اسفنج سلول باز پلیمری (پلی اورتان) به عنوان پیش ماده استفاده شد. سپس با انتخاب محلول های شیمیایی مناسب طبق یک دانش فنی مشخص، ابتدا سطح فوم پلیمری فعال شده و سپس به کمک روش رسوب دهی الکترولس، سطوح فعال شده پلیمر با یک لایه بسیار نازک از فلز مس پوشش گرفت. در مرحله نهایی با به کارگیری فرآیند رسوب دهی الکتریکی، لایه نازک مسی حاصل از فرآیند الکترولس به ضخامتی که دارای حداقل استحکام لازمه است، افزایش داده شد. نتایج نشان می دهد که در روش رسوب دهی الکتریکی می توان ضخامت 3-5 میکرونی مرحله الکترولس را به مقادیر 100-150 میکرون افزایش داد. نتایج میکروسکوپ الکترونی روبشی (SEM) نشان می دهد، ریزساختار پوشش حاصله به صورت گلوبولار است. همچنین با کنترل ضخامت رسوب مس در مرحله الکترولیز می توان سطح ویژه فوم را افزایش داد. نتایج نشان می دهد که زمان بهینه فرآیند الکترولس بین 5 تا 7 دقیقه و زمان الکترولیز یک ساعت است و فوم سلول باز مسی به دست آمده سبک بوده و سطح ویژه بالایی برای تبادل حرارت دارد.

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اطلاعات دوره: 
  • سال: 

    1402
  • دوره: 

    13
  • شماره: 

    4
  • صفحات: 

    151-171
تعامل: 
  • استنادات: 

    0
  • بازدید: 

    51
  • دانلود: 

    11
چکیده: 

A B S T R A C TToday, all officials involved with the challenges of city sustainability have accepted the idea of a SMARTer city, using more technologies, creating better living conditions and protecting the environment for a better quality of life. The central part of the metropolis of Tabriz is based on Region 8 and part of Region 10, a historical-cultural area with an area of 286 hectares and a population of about 40 thousand people in 8 neighbourhoods. This research was compiled to evaluate and explain the regeneration of the central part of Tabriz city with the approach of SMART growth and in line with the sustainable development of problematic neighbourhoods in the 8th district of Tabriz metropolis. The present review is methodologically practical, to describe and analyze the goals of regeneration based on library studies. The statistical population of the research includes experts and people living in the central context. In the first part, the Delphi method was used by asking experts. In the second part, the structural equation method of SPSS and AMOS software is used. According to the results of using the scales of design, pedestrian-oriented, intergenerational justice in the actual situation and 3 indicators of management and productivity, stable and value-creating jobs are in the potential situation. Also, two environmental indicators with the most direct and indirect effects and a cultural index have been decisive in the regeneration with the SMART growth approach in the central part of Tabriz city. Therefore, in the regeneration of the central part, the studied indicators should be used simultaneously and integrated into the reconstruction projects of the central fabric of the city to lead to SMART sustainabilityExtended AbstractIntroductionSMART growth is considered a lever for revitalizing neighborhoods and urban centers. In a general scenario of SMART growth, knowing the time and resources of investment provides a new and sustainable life in the city center and worn-out and old textures. Moreover, finally, it will improve the quality of urban neighborhoods, especially worn-out ones, and revive them. Tabriz metropolis, one of the most important and largest cities in the country, with a long history of settlement, especially the central and old texture, due to developments in information and communication technology, extensive environmental, social, and economic changes in terms of time requirements, the traditional texture of roads, Deterioration of residential units, lack of equipment, infrastructure and urban services and environmental problems have caused the failure and physically turned into inefficient and problematic textures. Urban planning and development science must adopt a new decision and approach to face the existing and complex issues of worn-out texture. The main problem of the research is to evaluate and explain the regeneration of the central texture and strengthen them in line with the sustainable development of the problematic neighborhoods of Tabriz metropolis according to the solutions and principles of SMART urban growth. Therefore, the main goal of this research is to answer the following question:- What are the effective indicators and components in the regeneration of the central texture of Tabriz metropolis with a SMART growth approach? MethodologyThis research is applied and fundamental in terms of purpose and descriptive-analytical. The collection methods are based on documentary and library studies, surveys, and interviews. In the first part, qualitative data was prepared with an open questionnaire and through interviews, as well as the review of documents and quantitative data used in this research numerically and through the weighting of Delphi questionnaires based on the consensus index model to determine importance, certainty, and priority. The panel members were 19 people (including 5 university faculty members, 7 field research experts, 4 executive experts, and 3 graduate students) selected based on the non-probability (targeted) method. In the second part, Cronbach's alpha method was exerted to measure the reliability of the questions, which was obtained as 0.89. In order to evaluate the validity of the questionnaire, the Lawshe method was exploited. The statistical population of the second part includes District 8 of Tabriz, which is the central texture of the city and is equal to 34,231 people. According to Cochran's formula, the sample size was equal to 379 people. Results and discussionIn the next step, path analysis was performed using AMOS 23 software to compare the integrated model with the hypotheses. The results of the path analysis, while verifying the structures, show that the value of the index of the critical ratio to the degree of freedom (CMIN/DF) is equal to 4.01, which is an optimal value for the model fit. Also, the goodness of fit index (GFI) is 0.952, which indicates the acceptability of this amount for the optimal fit of the model. The value of the root means the square error of estimation (RMSEA) is 0.065, which is acceptable because it is smaller than 0.08 and indicates the confirmation of the research model. Also, the Tucker-Lewis index (TLI) is 0.917, the comparative fit index (CFI) is 0.92, and the normalized parsimonious fit index (PNFI) is 0.882, which all indicate that the fit and verification of the research model are desirable.Therefore, none of the objects are removed and remain in the model. Therefore, it is confirmed that the factor structure of regeneration indicators with the SMART growth approach has reliability and construct validity. Also, the second-order factor analysis shows that the factor loadings of all regeneration indicators with the SMART growth approach are greater than 0.4 and are significant at the 95% probability level. According to the results, the environmental dimension with a factor loading of 0.94 has the most significant effect on urban regeneration with the SMART growth approach in the central texture of Tabriz city. After that, quality of life with a factor loading of 0.92, social dimension with a factor loading of 0.88, economic dimension with a factor loading of 0.83, physical dimension with a factor loading of 0.81, transportation dimension with a factor loading of 0.74 and cultural dimension in order with a factor loading of 0.72, are in the following ranks.According to the final structural model results, the environmental index has the highest value, with a direct effect of 0.594 and an indirect effect of 0.275. Moreover, after that, respectively, the quality of life index with a direct effect of 0.513 and an indirect effect of 0.236, a social index with a direct effect of 0.476 and an indirect effect of 0.217, an economic index with a direct effect of 0.451 and an indirect effect of 0.222, Physical with the direct effect of 0.435 and indirect effect of 0.205, mobility index with the direct effect of 0.373 and indirect effect of 0.182 and cultural index with the effect of direct values of 0.295 and indirect effect of 0.153 are influential in regeneration with SMART growth approach in the central part of Tabriz city. ConclusionIn this research, seven main indicators related to the subject were investigated. The results showed that the environmental index with the most significant direct and indirect effect is the focus of the evaluation. After that, dimensions and indicators of quality of life, social index, economic index, physical index, mobility index, and cultural index have been influential. According to the results, the urban environment index was analyzed as the most important factor at a high level, and this means that for urban regeneration with a SMART growth approach, improving the environmental and physical conditions in the worn-out and central texture of Tabriz city in the current situation is a priority. It is first. This is the most well-known part of regeneration with a SMART growth approach. The analysis results show that this is not the case only in the case of transportation infrastructure. However, more comprehensive urban infrastructure such as the urban landscape, open spaces, green and parks, etc. are also crucial in improving the physical conditions of the infrastructure. Also, this study's results show that the economic sector's importance is as important as improving the physical conditions of the infrastructure. In addition, in the worn-out texture of District 8 of Tabriz city, the sociocultural sector is essential, and the revival of historical and cultural resources is considered one of the urban regeneration options. Funding There is no funding support. Authors’ Contribution All of the authors approved the content of the manuscript and agreed on all aspects of the work.  Conflict of Interest Authors declared no conflict of interest. AcknowledgmentsWe are grateful to all the scientific.

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