فیلترها/جستجو در نتایج    

فیلترها

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بانک‌ها



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متن کامل


نویسندگان: 

رسولی علی اکبر

اطلاعات دوره: 
  • سال: 

    1381
  • دوره: 

    17-16
  • شماره: 

    1-4 (پیاپی 64-63)
  • صفحات: 

    213-233
تعامل: 
  • استنادات: 

    2
  • بازدید: 

    2716
  • دانلود: 

    558
چکیده: 

جغرافی دانان، از دیرباز، طراحی و بهره گیری از انواع مدل ها را همواره اصلی مهم در تحقیقات به شمار آورده اند. در دهه های گذشته، جغرافی دانان طبیعی در جهت حل مسایل موجود و پاسخگویی به سووالات طرح شده در قلمروهای جغرافیایی و به منظور رسیدن به اهداف از پیش تعیین شده، شیوه های مدلسازی متنوعی را تجربه نموده اند. در این رهگذر، آنان از فناوری های عصر خود به نحو مطلوب بهره برده و به منظور انعکاس و نمایش اصولی واقعیت های سطح کره زمین - از طریق انواع مدل ها - سبک متنوع و تعریف شده ای عرضه داشته اند.اما در دهه های اخیر، به دلیل رشد شگفت انگیز فناوری های رایانه ای، ابداع ابزارهای مشاهدات جدید، گسترش سیستم های ارتباطاتی، و مطرح شدن جنبه های کاربردی، ساختار و نحوه به کارگیری مدل ها در جغرافیای طبیعی نیز دستخوش تغییرات اساسی گردیده است.در این ارتباط، هدف اساسی مقاله حاضر مطرح کردن نقش انواع مدل ها در بیان واقعیت های مورد نظر قلمرو جغرافیای طبیعی است. بنابراین، ابتدا مقدمه ای بر این رشته مورد نیاز جوامع بشری ارایه می گردد. سپس موضوع و ویژگی های انواع مدل ها و بعضی از شیوه های مدلسازی نوین با عنایت بر انتظارهای جدید مطرح خواهد شد.

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نویسندگان: 

ASSEMPOUR A. | RAZI S.

اطلاعات دوره: 
  • سال: 

    2003
  • دوره: 

    4
  • شماره: 

    1
  • صفحات: 

    61-69
تعامل: 
  • استنادات: 

    0
  • بازدید: 

    414
  • دانلود: 

    0
چکیده: 

PHYSICAL MODELING of extrusion process has been studied to obtain qualitative and quantitative information. To observe the flow pattern during the process the plasticine specimen was made with layers of different colors (dark and light). The strain distribution was obtained by measuring the thickness of the plasticine layers and considering the axi-symmetric formulations. The stress distribution and subsequently the extrusion load were computed according to the strain distribution. To model the real frictional effect several ring compression tests have been performed. In order to verify the validity of the MODELING data, a similarity study between plasticine and Al 2024-T4 was made. The load obtained by this technique was compared with the results of ANSYS MODELING and slab method analysis.

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بازدید 414

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اطلاعات دوره: 
  • سال: 

    1390
  • دوره: 

    23
  • شماره: 

    2 (مسلسل 79)
  • صفحات: 

    134-139
تعامل: 
  • استنادات: 

    0
  • بازدید: 

    862
  • دانلود: 

    122
چکیده: 

زمینه و هدف: علی رغم آنکه برای افزایش حجم پروتز در بیماران دارای دنچر از MODELING plastic(MP) در کنار ماده بهسازی بافتی استفاده می شود، اما در رابطه با ترکیب و واکنش متقابل (MP) و ماده بهسازی بافتی تحقیقهای گسترده ای انجام نشده است. هدف از این مطالعه بررسی تاثیر دو جزء از ترکیبات ماده بهسازی بافتی روی ساختار و ترکیب شیمیایی (MP) می باشد.روش بررسی: در این مطالعه تجربی مدل های کامپاند به ابعاد 25 و ارتفاع دو میلی متر تهیه گردیدند. پس از آن نمونه ها به صورت تصادفی به سه گروه تقسیم شده و هر کدام از آنها به وسیله ترازوی دیجیتال وزن می گردید. سپس نمونه ها در سه محلول اتانول، DBP: Di Butyl Phthalate و سه مخلوط دو ترکیب ذکر شده 50% اتانول و DBP%50 قرار داده شد و در زمانهای دو، چهار، شش و 24 ساعت مجددا وزن می شد برای آنالیز داده ها از نرم افزار SPSS ویرایش 16 استفاده گردید و از آزمون نان پارامتریک Kruskal-Wallis استفاده شد.یافته ها: یافته های به دست آمده بیانگر این بود که اتانول نقش زیادی در حلالیت (MP) ندارد، در حالی که DBP تاثیر زیادی در حلالیت آن دارد و همچنین ترکیب اتانول و DBP در میان این سه نوع بیشترین تاثیر را در حلالیت (MP) دارد. (P=0.03)نتیجه گیری: DBP تاثیر زیادی در حلالیت(MP) ، دارد، ضمن آنکه ترکیب اتانول و DBP در میان این سه نوع دارای بیشترین تاثیر در حلالیت (MP) می باشد.

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مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources
اطلاعات دوره: 
  • سال: 

    1388
  • دوره: 

    21
  • شماره: 

    2 (مسلسل 71)
  • صفحات: 

    138-142
تعامل: 
  • استنادات: 

    1
  • بازدید: 

    1654
  • دانلود: 

    361
چکیده: 

زمینه و هدف: روشهای مختلفی برای آموزش بهداشت کودکان وجود دارد یکی از روشهایی که کمتر به آن پرداخته شده است تئاتر می باشد. هدف از این مطالعه بررسی میزان تاثیر این روش آموزشی بر بهداشت دهان و دندان دانش آموزان دختر مقطع ابتدایی شهر یزد بوده است.روش بررسی: این مطالعه نیمه تجربی به روش قبل و بعد و زمان اجرای آن نیمه دوم سال 83 بود. این بررسی روی دویست دانش آموز دختر مقطع ابتدایی انجام گردید. در هر منطقه شهر، یک دبستان و در هر دبستان به صورت خوشه ای از هر یک از مقاطع یک کلاس بیست نفری انتخاب گردید. روش جمع آوری اطلاعات، پرسشنامه ای بود که قبل و بعد از اجرای تئاتر میزان آگاهی، نگرش و عملکرد دانش آموزان به وسیله آن سنجیده شد. از آزمونهای آماری Chi-Square, Wilcoxon و بسته نرم افزاری SPSS برای مقایسه نتایج قبل و بعد از آموزش استفاده گردید.یافته ها: نتایج نشان داد که به طور کلی تئاتر در افزایش آگاهی، نگرش و عملکرد دانش آموزان در مورد بهداشت دهان و دندان موثر بوده است. تاثیر تئاتر به ترتیب بر آگاهی دانش آموزان بیشتر از نگرش و بر نگرش آنها بیشتر از عملکرد بود. (P<0.0001) در مورد رابطه سواد مادر با میزان آگاهی، نگرش و عملکرد دانش آموزان در مورد بهداشت دهان و دندان آزمون آماری نشان داد که تنها ارتباط سواد مادر با عملکرد معنادار بوده است. (021/0=P)، همچنین نتایج نشان داد که ارتباط معناداری بین مقطع تحصیلی دانش آموز با میزان آگاهی (020/0=P)، نگـرش (P=0.0001) و عملکـرد (022/0=P) وجود دارد، به طوری  که در مقاطع بالاتـر این مقادیـر افزایش می یابد.نتیجه گیری: نتایج این مطالعه نشان داد که اجرای سناریوی استفاده شده در این بررسی متناسب با مسایل فرهنگی هر منطقه در مدارس سطح شهرستان می تواند در جهت ارتقای سطح آگاهی، نگرش و عملکرد دانش  آموزان در مورد بهداشت دهان و دندان مورد استفاده قرار گیرد.

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بازدید 1654

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نویسندگان: 

Baghernejhad Elnaz

اطلاعات دوره: 
  • سال: 

    1402
  • دوره: 

    11
  • شماره: 

    2
  • صفحات: 

    29-60
تعامل: 
  • استنادات: 

    0
  • بازدید: 

    174
  • دانلود: 

    29
چکیده: 

ABSTRACT Despite a wide range of components and criteria affecting travel behavior presented through empirical research, the results of these studies are inconclusive, which could be due to the difference between these components and criteria in the study areas. Therefore, this research presented a method to determine which factors in different PHYSICAL developments affect travel behavior due to the differences in various PHYSICAL developments. The required information was collected through 271 questionnaires at the level of three neighborhoods of Monirieh, Koye Bimeh, and Koye Golestan in Tehran, Iran, as the old, conventional, and new neighborhoods, respectively. ANOVA test was exerted to analyze the significant difference between different development patterns in three neighborhoods. Dunnett's T3 was applied to determine which neighborhood caused the difference between groups. Also, the factors affecting travel behavior were obtained based on exploratory factor analysis indicators. Finally, by comparing the results of the ANOVA test and regression analysis, it was discovered that factors such as car ownership, dependence and pro-liking for private cars, density and access to educational centers and parks, access to medical and service centers, and variety and density of retail stores had been introduced as the factors affecting travel behavior due to the differences in development patterns. However, proximity to the public transportation station, accessibility preferences in choosing a residence, dependence, and pro-liking for other than a private car, having a license, number of children under five years old, and age have influenced travel behavior regardless of the variation between neighborhoods. Extended Abstract Introduction Finding factors affecting travel behavior has been one of the main concerns of transportation planners. However, in the last two decades, the importance of the influence of the features of the built environment, including land use, along with demographic-economic characteristics, travel behavior, and attitudes of people, has been raised by urban planners. Studies seek to find factors affecting travel behavior, especially land use characteristics. Despite presenting a wide range of components and criteria affecting travel behavior, the results of the studies are inconclusive, which could be due to the difference between these components and criteria in the study areas. Therefore, this research presented a method to determine which factors in different PHYSICAL developments affect travel behavior due to the differences in various PHYSICAL developments. In order to do this, it must first be determined whether the study areas/different development patterns have a significant difference in terms of travel behavior or not. In case of a positive answer to the previous question, the following question is which study areas caused this difference. The next question arises: -Which PHYSICAL and non-PHYSICAL characteristics affect travel behavior due to distinctions between different development patterns?   Methodology The present research method is analytical and experimental based on quantitative methods. This research chose the frequency of travel by private car, public transportation, and walking as the travel behavior. According to the research's purpose, indicators and criteria affecting travel behavior were extracted after reviewing the theoretical and experimental literature. Then, the required information was collected through 271 questionnaires at the level of three neighborhoods of Monirieh, Koye Bimeh, and Koye Golestan as the old, conventional, and new neighborhoods, respectively. The questionnaire was compiled as a Likert scale in five parts of travel information, demographic-economic characteristics, perceptual characteristics of land use, travel habits, and access preferences of people in choosing their residence. ANOVA test was used to analyze the significant difference between different groups of a characteristic (here, different development patterns or the three case studies). Dunnett T3 was exerted to determine which neighborhood caused the difference between groups. Also, the factors affecting travel behavior were obtained based on exploratory factor analysis indicators. Finally, by comparing the results of the ANOVA test and regression analysis, it was discovered which factors affecting travel behavior were due to the differences in study areas and which factors affect travel behavior regardless of development patterns.   Results and discussion This research aims to identify the factors affecting travel behavior due to the differences in development patterns. In this regard, the findings in line with the first research question show that the frequency of three modes of travel, by private car, transportation, and pedestrian, differ significantly in the three neighborhoods. Furthermore, ANOVA test results depict that there is a significant difference between these three neighborhoods in terms of factors affecting travel behavior, such as perceptually environmental characteristics of the neighborhood, dependence and pro-liking for personal cars, variety and density of retail stores, density and access to educational units and parks, access to medical and service centers, and car ownership. Finally, by comparing the results of the ANOVA test with the regression analysis assessing the relationship between PHYSICAL and non-PHYSICAL factors (the same indicators in the same study areas) with travel behavior, the factors affecting travel behavior owing to different development patterns were identified. Factors such as car ownership, dependence and pro-liking for private cars, density and access to educational units and parks, access to medical and service centers, and variety and density of retail stores have been introduced as the factors affecting travel behavior due to the differences in development patterns. However, proximity to the public transportation station, accessibility preferences in choosing a place of residence, dependence, and pro-liking for other than a private car, having a certificate, number of children under five years old, and age have influenced on travel behavior regardless of the variation between neighborhoods (different PHYSICAL development patterns).   Conclusion In In order to discover the factors affecting travel behavior due to the differences in patterns of PHYSICAL development, this research has provided a more detailed analysis of the factors affecting travel behavior. It has achieved more accurate components than previous studies in this regard. Detailed analysis of studies related to travel behavior and finding the main components affecting it, considering the extent of variables and data, can pave the way for professionals in transportation planning and urban planning, in addition to providing detailed methods and criteria in the related literature.   Funding There is no funding support.   Authors’ Contribution Authors contributed equally to the conceptualization and writing of the article. All of the authors approved thecontent of the manuscript and agreed on all aspects of the work declaration of competing interest none.   Conflict of Interest Authors declared no conflict of interest.   Acknowledgments  We are grateful to all the scientific consultants of this paper.

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اطلاعات دوره: 
  • سال: 

    1401
  • دوره: 

    12
  • شماره: 

    47
  • صفحات: 

    75-93
تعامل: 
  • استنادات: 

    0
  • بازدید: 

    138
  • دانلود: 

    11
چکیده: 

Background: The expansion of the use of audio and video media technology has faced society with many medical, cultural and economic challenges. In the meantime, excessive use of mobile phones can cause many problems. Objective: The aim of this study was to construct and validate a questionnaire on PHYSICAL and psychological injuries of mobile phones. Method: The method of the present study was descriptive-correlational and confirmatory factor analysis. The statistical population of the study consisted of all citizens of Khorramabad with a diploma or higher in 1399, which was selected as a statistical sample by available sampling method of 200 people online and virtual. Results: The results showed that the factorized PHYSICAL and psychological harm questionnaire of cell phone with 42 questions and 10 components (fear of loss, vibration syndrome, duck syndrome, nomophobia, insomnia, hearing problem, eye syndrome, tunnel and neck syndrome SMS) and has good reliability, validity and flexibility in terms of psychometrics. Discussion and Conclusion: The questionnaire of factor analysis of PHYSICAL and psychological injuries of mobile phones can be used to identify and study the PHYSICAL and psychological injuries of mobile phones.

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

CERMAK J.E.

اطلاعات دوره: 
  • سال: 

    1995
  • دوره: 

    54-55
  • شماره: 

    ASIA-PACIFIC SYMPOSIUM ON WIND ENGINEERING
  • صفحات: 

    439-455
تعامل: 
  • استنادات: 

    1
  • بازدید: 

    166
  • دانلود: 

    0
کلیدواژه: 
چکیده: 

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بازدید 166

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اطلاعات دوره: 
  • سال: 

    2006
  • دوره: 

    7
تعامل: 
  • بازدید: 

    152
  • دانلود: 

    0
کلیدواژه: 
چکیده: 

ONE OF THE IMPORTANT TOPICS IN CATENARY RISER DESIGN IS THE SCR TOUCH DOWN REGION AND ITS INTERACTION WITH THE SEABED. TWENTY-TWO PIPE-SOIL INTERACTION TESTS HAVE BEEN CARRIED OUT. THE SOIL USED IN THE STUDY IS A CLAY FROM OFFSHORE WEST AFRICA. THIS UNUSUAL MATERIAL, WAS ARTIFICIALLY PRE-CONSOLIDATED UNDER SURCHARGE AND THEN HOMOGENIZED. ALL TESTS WERE CARRIED OUT ON A STIFF, ALUMINIUM PIPE SECTION. PORE PRESSURES WERE MEASURED AT THE PIPE-SOIL INTERFACE AT A NUMBER OF LOCATIONS. A LOAD CELL ON THE PIPE SUPPORT PLATES WAS USED TO OBTAIN THE NET SOIL FORCES P (HORIZONTAL) AND Q (VERTICAL) ON THE PIPE. THE FORCES P AND Q DUE TO HORIZONTAL SWEEPING H FROM THE CENTRE OF A PREFORMED TRENCH OF WIDTH 3D AND DEPTH H, WERE THE FOCUS OF INVESTIGATION IN THESE TESTS.

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نویسندگان: 

CERMAK J.E. | TAKEDA K.

اطلاعات دوره: 
  • سال: 

    1985
  • دوره: 

    21
  • شماره: 

    1
  • صفحات: 

    51-67
تعامل: 
  • استنادات: 

    1
  • بازدید: 

    169
  • دانلود: 

    0
کلیدواژه: 
چکیده: 

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

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اطلاعات دوره: 
  • سال: 

    1400
  • دوره: 

    51
  • شماره: 

    4
  • صفحات: 

    431-441
تعامل: 
  • استنادات: 

    0
  • بازدید: 

    147
  • دانلود: 

    24
چکیده: 

Different types of contact, including contact between node pairs, any-contact of nodes, and contacts of the entire network, are used to characterize social relations in mobile social networks. Different modes of routing, from the point of view of message delivery semantics, encompass unicasting, multicasting, any-casting, and broadcasting. Studies have shown that using probability distribution functions of contact data, which is mainly assumed to be homogeneous for nodes, improves the performance of these networks. However, there exists an important challenge in studies on distributions. A lot of works apply the distribution of one type of contact to other types. Hence in routing applications, it causes to use of the distribution of one type of contact for any mode of routing. This study provides a complete solution to model each type of homogeneous contact data distribution and to use them in different modes of routing. We propose a routing algorithm that uses this new model. Results show that our solution improves the average latency of comparing methods Epidemic, TCCB, and DR about 3.5-times, 30%, and 45%, respectively. It achieves a delivery rate of about 5% and 6%, and average latency about 6% and 8% better than that of DR and TCCB, respectively.

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email sharing button
email sharing button
email sharing button
sharethis sharing button