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Issue Info: 
  • Year: 

    2021
  • Volume: 

    21
  • Issue: 

    4
  • Pages: 

    7-17
Measures: 
  • Citations: 

    0
  • Views: 

    135
  • Downloads: 

    0
Abstract: 

On the mechanics of solids, in many cases, the body is affected by mechanical force and heat load simultaneously. One of the most widely used and important parameters in the optimal design of engineering problems is the utilization of the sensitivity numbers respect to the values of its design variables. Sensitivity numbers or derivative of a function with respect to a design variable show how a dependent variable responds to the design variables changes. The present paper analyzes sensitivity in thermomechanical problems using the complex variables method (CVM). The most important drawback of past methods for the analysis of sensitivity values such as finite difference method (FDM) and semi-analytical method (SAM) is the dependence of the calculated values of sensitivity numbers on the step size, which leads to unreliable answers. Complex variables method is a new robust approach that uses a Taylor series extension in a complex space and which is not sensitive to step size, disturbance and given that during the computational process, subtraction of two numbers is almost equally avoided, so does not influence from error caused by removing meaningful figures that commonly occur in finite difference method due to subtracting of two near the number. As a result, it is possible to achieve accurate answers by choosing a small step size. Also, it has some potential advantages over other methods. At first order sensitivities using the complex variables method, the implementation is straightforward, only requiring a perturbation of the finite element mesh along the imaginary axis. Implementation of sensitivity using complex variables method requires complex variable finite element code such that complex nodal coordinates can be used to implement a perturbation in the shape of interest in the complex domain. All resulting finite element outputs such as temperature, displacements, strains, stresses, etc. become complex and accurate derivatives of all finite element outputs to the shape parameter of interest are available. So, unlike most methods, using the proposed method does not require calculations to select the appropriate change in step size. However, the value of the change in step size is not known in advance and changes from one problem to another. Therefore, it is necessary to repeat the simulation to ensure the results. The study found that the source of the rounding error was due to the rotation of the element, this also makes it difficult to use two methods, semi-analytical and finite difference. In this case, the use of CVM is not limited and can be achieved by effective answers without worrying about the small step size. In the present study, to examine how efficient and valid the proposed method is, how it works to solve several thermomechanical problems is described. The methodologies are demonstrated using two-dimensional finite element models. Obtained sensitivity derivatives are compared to the semi-analytical solution and also finite difference method and it is shown that the proposed method is effective and can predict the stable and accurate sensitivity results. The complex variable method presented in this study can be used to solve a wide range of engineering problems.

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

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Issue Info: 
  • Year: 

    2007
  • Volume: 

    9
  • Issue: 

    3 (SN 35)
  • Pages: 

    317-323
Measures: 
  • Citations: 

    0
  • Views: 

    3413
  • Downloads: 

    0
Abstract: 

Introduction: Carney Complex is an autosomal dominant syndrome that is defined with different tumors including myxoma in different organs, endocrine tumors and lentiginosis lesions. This is the first case report of this syndrome from Iran.Case: The patient is a 27 year old girl, referred with flank pain. Physical examination revealed hirsutism, truncal obesity, hyperpigmantasion and hypertension; Cushing's syndrome was suggested and confirmed with related classic biochemical tests. She had history of cardiac myxoma during her childhood and had been operated twice.Pituitary microadenoma and right adrenal adenoma were reported on MRI and CT-scan, respectively. Initially laparascopic right adrenalectomy was done; as expected, no remission in signs of Cushing's syndrome was observed after surgery. By laparoscopic adrenalectomy of the other site, Cushing's syndrome resolved. Pathologic report of 1st operation was adrenal adenoma with surrounding pigmented micronodular hyperplasia and of the 2nd one was just pigmented micronodular hyperplasia.Conclusion: We have reported a patient with Carney syndrome along with Cushing's syndrome due to bilateral adrenal hyperplasia and an adenoma in contralateral adrenal and microadenoma of the pituitary as an incidentaloma. This is a new presentation of Carney syndrome.

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

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Issue Info: 
  • Year: 

    2024
  • Volume: 

    13
  • Issue: 

    4
  • Pages: 

    1-20
Measures: 
  • Citations: 

    0
  • Views: 

    42
  • Downloads: 

    8
Abstract: 

The city's regeneration is one of the strategies that lead to urban deterioration and inefficient textures towards revitalization. Using systems thinking on the subject of reinvention can lead to the identification of complex systems that are considered effective in producing and reproducing worn-out textures. In this regard, this study was to benefit from a systemic approach in identifying the the roots of the production and reproduction of historical/worn-out textures in Semnan city. The leading research is among the applied research, and in terms of information and data analysis, it uses the descriptive-analytical method. The tool for collecting information is also in documents and surveys. The statistical population of the research was 18 university professors, experts, and officials familiar with the urban fabric of Semnan, who were selected by the snowball method. In the end, using experts' opinions, 24 variables were selected as effective drivers of Semnan's production-reproduction system of worn tissue. MicMac software was used for structural-interpretive analysis of variables. The results show that the rules and regulations governing the regeneration of the studied area are the most important and effective factors. Also, the special ownership conditions governing barren, ruined, and ruined lands have caused the private sector to have no incentive to invest in this area and reproduce the existing conditions. With the continuation of the current process, the existing situation is reproduced. Breaking this round of the reproduction process requires a constructive look at the target neighborhoods from the city administration and government agencies, which can provide the basis for the presence of private sector investors in these neighborhoods

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

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Author(s): 

HASSANZADEH M. | KASHANI S.

Issue Info: 
  • Year: 

    2019
  • Volume: 

    19
  • Issue: 

    1
  • Pages: 

    237-246
Measures: 
  • Citations: 

    0
  • Views: 

    510
  • Downloads: 

    0
Abstract: 

In this paper, extended complex variables method (ECVM) is presented in fluid flow problems for the first and second-order sensitivity analysis. The finite element method is used to solve the Navier-Stokes equations, and the complex variables method is implemented to it. In the complex variables method, a complex step that only includes the imaginary part is used, but in its development, it uses a complex step that includes both the imaginary part and the real part to achieve higher performance. In the first-order sensitivity calculation, the results are not dependent on the step size, but in the second-order sensitivity, the results of the sensitivity depending on the step size and inevitably the developed formulas should be used to obtain higher accuracy. The proposed method is first validated for a problem with a closed-form solution, and the convergence rate is investigated and, then, applied to a uniform flow past a cylindrical cylinder and, finally, the results are compared by finite difference method. The results show that the range of accuracy for second-order sensitivity in the extended complex variable method is doubled compared to the complex variable method and it can be reduced to 10-12. It means that the effectiveness of the proposed method has increased. The introduced method is applicable to a wide range of problems with simple and complex parameters.

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Issue Info: 
  • Year: 

    0
  • Volume: 

    15
  • Issue: 

    2
  • Pages: 

    45-63
Measures: 
  • Citations: 

    0
  • Views: 

    444
  • Downloads: 

    0
Abstract: 

از زمانی که برای اولین بار اختلال حرکتی که امروزه تحت عنوان DVD شناخته می شود، گزارش شد بیش از یک قرن می گذرد. طی این مدت محققین مختلف آن را مورد بحث قرار داده و تئوری های متعددی را برای بروز آن قایل شده اند. با توجه به این که DVD همیشه یکی از مشکلات تشخیصی و درمانی در بیماران استرابیسم می باشد، در مقاله ای که پیش رو دارید تلاش شده است مجموعه ای از این تحقیقات و تئوری ها ارایه گردد.

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

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Author(s): 

METWALLY M.S.

Issue Info: 
  • Year: 

    1999
  • Volume: 

    2
  • Issue: 

    -
  • Pages: 

    42-46
Measures: 
  • Citations: 

    1
  • Views: 

    148
  • Downloads: 

    0
Keywords: 
Abstract: 

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

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Issue Info: 
  • Year: 

    2023
  • Volume: 

    11
  • Issue: 

    2
  • Pages: 

    61-74
Measures: 
  • Citations: 

    0
  • Views: 

    172
  • Downloads: 

    27
Abstract: 

ABSTRACTDuring the last century, ports of Persian Gulf become the most important storage, refining and transportation of crude oil, oil derivation, petrochemical products and also, business activities. Nowadays, due to functional diversity between ports, the impact of port activities on the development of urban spaces will be different, and this issue leads to structural differences of port cities. The purpose of this research is to identify the key variables affecting the relations and spatial structure of port-city in Dubai as the most thriving and successful port-city in the Persian Gulf. This research is based on deductive reasoning and carried out by analysis of cross effects with secondary data (results of other prominent articles) and also primary data (questionnaire). sampling method is based on purposive sampling and Micmac software was used to analyze the data. Output of Micmac software shows the position of the instability of the system. Therefore, the position of each variables in the conceptual model can be categorized to driver, linkage, dependent, and autonomous factors. The research findings indicate 4 variables (like as “income, cost and investmnets in port-city”) can be introduced as a driver factor, 5 variables (like as “advanced multimodal transportation in the port”) can be introduced as a linkage factor, 6 variables (like as “quality of living environment and desirable city”) can be introduced as a dependent factor, 3 variables (like as “environmental protection and sustainable development of the city-port”) can be introduced as an autonomous factor. The rapid development of Dubai can be explained by the purposeful distribution of revenues from trade and tourismExtended AbstractIntroductionDuring the last century, ports of Persian Gulf become the most important storage, refining and transportation of crude oil, oil derivation, petrochemical products and also, business activities. The global increase in oil demand since the 1950s led to the creation of discovery of new oil wells and large industrial areas. With the construction of new oil or gas facilities in the port areas, increasing oil revenues contributed to the countries of the Persian Gulf region and form a new geographical relationship between ports and coastal cities which had an impact on the spatial structure and relation of them. Nowadays, due to functional diversity between ports, the impact of port activities on the development of urban spaces will be different, and this issue leads to structural differences of port cities. In the 1950s, Containerization (container loading technology) was based in some of the world's ports and created a huge transformation in the shipping industry, which had a significant impact on the development of ports. Although the ports of the Persian Gulf have made a significant contribution to the economic growth and physical development of other ports in the world, but few researches have been done on the variables and factors affecting the development of the spatial structure of the important ports of the Persian Gulf. This region, due to its unique geographical location, has always been considered as a most important corridor in the field of economic and transportation throughout history. Some of the most important energy and commercial ports in this region are: Dubai, Manama, Kuwait, Dammam, Doha, Bushehr, Bandar-Abbas and Assaluyeh. In this regard, the purpose of this research is to identify the key variables affecting the relations and spatial structure of port-city in Dubai as the most thriving and successful port-city in the Persian Gulf. MethodologyThis research is based on deductive reasoning and carried out by analysis of cross effects with secondary data (results of other prominent articles) and also primary data (questionnaire). The method used in this research is quantitative and the sampling method is based on purposive sampling. the variables affecting the spatial structure of port-city relations were identified in the form of a review of 31 prominent articles. 25 experts (who had comprehensive knowledge and information about the development process of the city-port of Dubai) participated to determine the effectiveness or influence of variables. Finally, the output of data analysis was done by the Micmac software. Results and discussionOutput of Micmac software shows the position of the variables in the diagram that it indicates their status in the system and their role in the dynamics and changes of the system. The method of distribution and dispersion of the variables in the spatial structure of port-city relations indicates the instability of the system. Therefore, based on the output of the system, the position of each variables in the conceptual model can be identified in five categories (driver, linkage, dependent, autonomous and regulatory variables). According to the results, some variables such as “the changes in the strategic positions” and “geopolitics of port-city”, “the modification of the management method” and “regional planning of the ports”, “the promotion of local governance in the relations between port-city” and “the way of national and international management of ports have been introduced as driver variables. On the other hand, five variables consist of “advanced multimodal transportation in the port” and “income, cost and investment in the port-city”, “the contrast and physical integration of the port - city space”, “the development of various industrial and production activities in the ports and their local hinterland” and “their qualities Financial and commercial policies of ports” have been introduced as linkage variables. Findings of research also shows that some variables consist of “quality of living environment and desirable city”, “quantity and quality of transit corridors (rail, road and air) to hinterland”, “construction and launching the new port (sea port or dry port)”, “terminal facilities and infrastructure and warehousing”, “conflict or convergence between the city and the port” and “increase in population growth rate and migration to the port - city” categorized as dependent variables. Three variables including “cultural and historical background of ports”, “use of cheaper energy, Less-polluted, clean and renewable energies in the city-port” and “environmental protection and sustainable development of the city-port” categorized as autonomous variables. Finally, a variable with the title of “improvement in management and information technology and development in loading, unloading and storage of commodities” have been introduced as regulatory variables. The findings of this research have a remarkable similarity with other researches carried out in the field of city-port relation and clearly emphasize the direct impact of the "investment in port-city" in the development of them. For example, Grossmann (2008) emphasized that city-port of Hamburg has become one of the largest ports in Northern Europe during the last few decades due to huge domestic and foreign investment. ConclusionThis research carried out in order to introduce and explain the key variables affecting the development of the spatial structure of the port-city of Dubai. On this basis, 21 variables have been extracted by systematic reviews of prominent articles. In the following, 25 experts were selected with the purposive sampling method. Among the 21 variables extracted, 4 variables (like as “geopolitics of port-city”) introduced as a driver factor, 5 variables (like as “advanced multimodal transportation in the port”) introduced as a linkage factor, 6 variables (like as “quality of living environment and desirable city”) introduced as a dependent factor, 3 variables (like as “environmental protection and sustainable development of the city-port”) introduced as an autonomous factor. The rapid development of Dubai can be explained by the purposeful distribution of revenues from trade and tourism. A part of these revenues has been directed towards investment in important transportation infrastructures such as airports and ports of this city. These strategies have a wide impact on improving the economic growth of the city and the development of the port in order to adapt with the global trade and advanced technologies. FundingThere is no funding support. Authors’ ContributionAuthors contributed equally to the conceptualization and writing of the article. All of the authors approved the content of the manuscript and agreed on all aspects of the work declaration of competing interest none. Conflict of InterestAuthors declared no conflict of interest. Acknowledgments We are grateful to all the scientific consultants of this paper.

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Issue Info: 
  • Year: 

    2016
  • Volume: 

    42
  • Issue: 

    3
  • Pages: 

    521-537
Measures: 
  • Citations: 

    0
  • Views: 

    342
  • Downloads: 

    98
Abstract: 

Please click on PDF to view the abstract.

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

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Author(s): 

MARSAGLIA G. | TSANG W.W.

Issue Info: 
  • Year: 

    2000
  • Volume: 

    5
  • Issue: 

    -
  • Pages: 

    1-7
Measures: 
  • Citations: 

    1
  • Views: 

    115
  • Downloads: 

    0
Keywords: 
Abstract: 

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

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Issue Info: 
  • Year: 

    2018
  • Volume: 

    10
  • Issue: 

    1
  • Pages: 

    1-16
Measures: 
  • Citations: 

    0
  • Views: 

    472
  • Downloads: 

    0
Abstract: 

Background and objectives: CoQ10 is a lipophylic natural antioxidant with fundamental role in mitochondria bioenergetics. The positive effect of CoQ10 in therapy of many diseases is attributed to its antioxidant and bioenergetics properties. Reduction of endogenous synthesis of CoQ10 by the ageing, insufficient amount in the food and several health benefits of CoQ10 have led to food fortification. The objective of this study was to microencapsulate CoQ10 by complex coacervation method and determinate of optimum mixture component (β-lactoglobulin (β-lg), Arabic Gum (AG), Oil containing CoQ10 and water) to achieve maximum value of microencapsulation efficiency (ME) and payload. Due to temperature sensitive characteristic of CoQ10, Gelatin was replaced with β-lg and combination of β-lg and AG were used to microencapsulation of Oil containing CoQ10. Materials and methods: At first CoQ10 powder and olive oil were poured in opaque tube and stirred in incubator shaker for 24h. Then solutions of β-lg and GA were prepared at 1-4% (w/w), by dispersing the required amount of them in deionized water and microcapsules were formed by adding oil phase containing CoQ10 to the β-lg solution and preparation of emulsion, adding the GA solution and adjusting pH to 4. After separation of microcapsules freeze dryer was used to dehydration of them, and Morphology of CoQ10 microcapsules was examined using a Scanning Electron Microscope (SEM) and an optical microscope. The particle size and the particle size distribution of moist microcapsules were determined using a particle size analyzer. In the next stage it was used from n-hexane to extracting oil and extracted oil was dissolved in 1, 4-dioxane and analyzed by a high performance liquid chromatography (HPLC) system, and microencapsulation efficiency was calculated for microcapsules before and after freeze drying. At the end the effect of oven drying and defrost on microencapsulation efficiency was studied for 5 formulations. Results: ME values before drying for all formulations except one sample (containing: 4%β-lg, 4%AG, 5%Oil and 87% water) were in the range of 94. 05-99. 01%. Variation in ME and payload values after freeze drying was in the range of 34. 91-92. 45 and 24. 78-83. 75%, respectively and sample containing 2. 5% (w/w) β-lg and 2. 5% (w/w) AG and 5 % (w/w) oil obtained the highest ME value, an homogeneous particle size distribution and had a smooth and free of pores surface. Conclusion: Based on the results, formulation containing 2. 5% (w/w) β-lg and AG and 5 % (w/w) oil can be successfully used to microencapsulation of CoQ10.

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

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