How do red and infrared low-level lasers affect folliculogenesis cycle in rat’s ovary tissue in comparison with clomiphene under in vivo condition

Tabriz University of Medical Sciences, 5/89/137Peer reviewedPublisher PD

Analysis of Coverage Region for MIMO Relay Network with Multiple Cooperative DF-Relays

We study and analyze coverage region in MIMO communication systems for a multiple-relay network with decode-and-forward (DF) strategy at the relays. Assuming that there is a line-of-sight (LOS) propagation environment for source-relay channels and channel state information is available at receivers (CSIR), we consider the objective of maximizing coverage region for a given transmission rate and show numerically the significant effect of propagation environment on capacity bounds, optimal relay location and coverage region. Also, we study the situation in which two adjacent relays cooperate in transmission signals to the destination and show analytically that the coverage region is extended compared to noncooperative scenario.Comment: Accepted for publication in International Symposium on Wireless Communication Systems (ISWCS) 201

Application of Monte Carlo calculations for validation of a treatment planning system in high dose rate brachytherapy

AbstractAimThe accuracy of treatment planning systems is of vital importance in treatment outcomes in brachytherapy. In the current study the accuracy of dose calculations of a high dose rate (HDR) brachytherapy treatment planning system (TPS) was validated using the Monte Carlo method.Materials and methodsThree 60Co sources of the GZP6 afterloading brachytherapy system were modelled using MCNP4C Monte Carlo (MC) code. The dose distribution around all the sources was calculated by MC and a dedicated treatment planning system. The results of both methods were compared.ResultsThere was good agreement (<2%) between TPS and MC calculated dose distributions except at a point near the sources (<1cm) and beyond the tip of the sources.ConclusionsOur study confirmed the accuracy of TPS calculated dose distributions for clinical use in HDR brachytherapy

Content Marketing Process Model: A Meta-Synthesis of the Literature

The purpose of this study was to design and validate a content marketing process model based on the systematic review of the literature. The research approach of the present study was a combination of two stages. Firstly, using the meta-synthesis method, all dimensions of content marketing are identified and the research model is presented. Then, in order to validate the model, the fuzzy Delphi method was conducted in three rounds. The population of the first stage was consisted of 652 documents in this field, of which 55 were selected. The second population includes 16 experts in the field of content marketing who participated in all three rounds of the Delphi. Content marketing process model was achieved in four stages of planning, production, distribution and communication, measurement and optimization. In each stage, the steps and components necessary to implement the marketing content were identified and explained. Considering the use of two methods of meta-synthesis and Fuzzy Delphi, the proposed model is sufficiently valid and can be used as a roadmap for the establishment and implementation of content marketing performance in different companies and industries

The Effect of Digital Age on Youth Reading Habits and Practices

Purpose: In the digital age, web applications work as machines that swallow time rapidly. A new generation tendency to use these tools for entertaining and information gathering has changed their habits in type of selected materials and reading practices. In other words, although users currently receive information from the Internet, they have increasingly become superficial readers who have a little interest to read deeply in digital format. This unwillingness not only changes reading habits of young adults, but also transforms their web browsing and information processing. The present study aims to investigate the effect of digital environment on users’ reading habits. Methodology: We used a case study approach and survey method was used. In this research, a questionnaire was used as a data collecting method. The research population included all undergraduate students in all disciplines (=1000) who study in “Toos Institute of Higher Education”. 100 students were selected as a sample study based on the accessibility principle. Findings: The results indicated that participants commonly believed that the Internet increases interactive reading (56%), expanded reading (44%), and superficial reading (49%). In contrast, it reduces concentrated reading (34%) and in-depth reading (28%). In addition, the Internet increases reading in the formats such as news (63 %), general knowledge (85%), special literature (63%), and pornography (42%). In contrast, it has no any significant impact on religious literature (35%) and literary literature (40%). Originality/Value: Value of this research lies in its effort to show altered reading habits, methods and formats in the digital environment. It can be a useful source for accommodation with new interests and find new methods for deepen reading in these new behaviors

Partitioned semi-implicit methods for simulation of biomechanical fluid-structure interaction problems

This article is published under a CC BY licence. The Version of Record is available online at: http://dx.doi.org/10.1088/1742-6596/745/3/032020.This paper represents numerical simulation of fluid-structure interaction (FSI) system involving an incompressible viscous fluid and a lightweight elastic structure. We follow a semi-implicit approach in which we implicitly couple the added-mass term (pressure stress) of the fluid to the structure, while other terms are coupled explicitly. This significantly reduces the computational cost of the simulations while showing adequate stability. Several coupling schemes are tested including fixed-point method with different static and dynamic relaxation, as well as Newton-Krylov method with approximated Jacobian. Numerical tests are conducted in the context of a biomechanical problem. Results indicate that the Newton-Krylov solver outperforms fixed point ones while introducing more complexity to the problem due to the evaluation of the Jacobian. Fixed-point solver with Aitken's relaxation method also proved to be a simple, yet efficient method for FSI simulations.Peer ReviewedPostprint (published version

Developing numerical methods for fully-coupled nonlinear fluid-structure interaction problems

This thesis is dedicated to developing numerical methods to solve fluid-structure interaction (FSI) problems. FSI features in a vast range of physical systems and has a wide application in engineering. The work of this thesis is focused on the partitioned methods, mostly due to their features of modularity, robustness and reliability. In a partitioned approach, separate solvers are used for the fluid and structural sub-problem domains and a coupling method is devised to account for their mutual interaction. Moreover, the thesis is focused on FSI problems with strong added-mass effect, which are more challenging to solve numerically. For such FSI problems, normally an implicit partitioned method is used which enforces the coupling conditions on the interface through coupling iterations between the fluid and structural solvers. However, these methods are computationally expensive. In this work we follow a semi-implicit approach to develop stable, efficient and accurate numerical methods for FSI problems. In these methods, the fluid pressure term is segregated and strongly coupled to the structure via coupling iterations. However, the remaining fluid terms and the geometrical nonlinearities are treated explicitly. Strong coupling of the fluid pressure term provides for the stability of the method in FSI problems with strong added-mass effect, while loose coupling of the remaining terms reduces the computational cost of the simulations. The work of this thesis could be divided into three major parts. In the first part, we have developed a simple, efficient and robust semi-implicit coupling method for FSI problems with strong added-mass effect. The proposed method is simple and modular. An extensive set of numerical tests were carried out and the results were compared both to literature data (numerical and experimental), as well as domestic results obtained by using a fully-implicit coupling method. Results showed that the proposed method considerably reduces the computational cost of the simulations without degrading the stability or accuracy of the solution. Moreover, the robustness of the method is demonstrated through numerical tests. Furthermore, we have tried to further analyze the semi-implicit methods in order to gain a better understanding of several unaddressed issues concerning different aspects of these methods. The second major part of this thesis is focused on the temporal accuracy of the semi-implicit coupling methods for FSI problems. The semi-implicit methods in the literature appear to be only first-order in time. Most semi-implicit methods rely on using a projection method for the fluid equations, while extending the temporal accuracy of the projection methods is not straightforward. Moreover, mesh-conforming FSI solution methods require solving the ALE form of the Navier-Stokes equations on a moving mesh, which does not necessarily preserve the order of accuracy of the method on a fixed grid. Furthermore, if the FSI coupling technique is not properly designed, the second-order accuracy for the coupled problem is not guaranteed, even though each sub-problem possessed such accuracy. In this work, we have proposed a second-order time accurate semi-implicit method for FSI problems and demonstrated its second-order accuracy through rigorous numerical tests. The last major part of this thesis is concerned with computational efficiency and parallel scalability of the developed methods for numerical solution of complex FSI problems on massively-parallel supercomputers. We have presented a scalable parallel framework for partitioned solution of FSI problems through multi-code coupling. Two instances of our in-house software is used to solve the fluid and structural sub-problems. The communication between the single-physics solvers are carried out using an external coupling library. Parallel efficiency and scalability of the coupled framework is demonstrated in solving practical FSI test cases.Esta tesis está dedicada al desarrollo de métodos numéricos para resolver problemas de interacción de fluido-estructura (FSI). Esta fenomenología aparece en una amplia gama de sistemas físicos y aplicaciones en ingeniería. El trabajo se centra en los métodos de partición, principalmente debido a sus características de modularidad, robustez y fiabilidad. En estos métodos se utilizan solvers distintos para los dominios de fluido y estructura, siendo esencial la técnica de acoplamiento para tener en cuenta su interacción mutua. Además, la tesis se centra en los problemas del FSI con un fuerte efecto de "masa agregada", que son más complejos de resolver numéricamente. Normalmente se usa un método de partición implícito que impone las condiciones de acoplamiento en la interfaz a través de iteraciones entre los solucionadores de fluido y de estructura. Sin embargo, estos métodos son computacionalmente costosos. En esta tesis seguimos un enfoque semi-implícito que permite métodos numéricos estables, eficientes y precisos, en donde el término de presión del fluido está segregado y fuertemente acoplado a la estructura a través de iteraciones de acoplamiento. Sin embargo, los términos fluidos restantes y las no linealidades geométricas se tratan explícitamente. El fuerte acoplamiento del término de presión del fluido proporciona la estabilidad del método en problemas de FSI con un fuerte efecto de masa agregada, mientras que el acoplamiento de los términos restantes reduce el coste computacional. La tesis se divide en tres partes principales. En la primera se desarrolla un método de acoplamiento semi-implícito eficiente y robusto para problemas con un fuerte efecto de masa agregada. El método propuesto es simple y modular. Se llevó a cabo un extenso conjunto de pruebas numéricas. Los resultados se compararon con datos de la literatura (numéricos y experimentales), así como con resultados propios obtenidos mediante el uso métodos de acoplamiento totalmente implícitos. Las pruebas realizadas mostraron que el método propuesto reduce considerablemente el coste computacional de las simulaciones sin degradar su estabilidad y precisión. Además, se ha analizado más a fondo los métodos semi-implícitos con el fin de obtener una mejor comprensión de varias cuestiones no abordadas en relación con algunos aspectos de estos métodos. La segunda parte de esta tesis se centra en la precisión temporal de los métodos de acoplamiento semi-implícitos para problemas de FSI. La mayoría de los métodos semi-implícitos propuestos se basan en el uso de técnicas de proyección para las ecuaciones del fluido, con aproximaciones de primer orden temporal, no siendo sencilla su extensión a alto orden. Además, los métodos de malla-conforme requieren la resolución ALE de las ecuaciones de Navier-Stokes en mallas en movimiento, lo que no necesariamente conserva el orden de precisión del método en una cuadrícula fija. Si la técnica de acoplamiento FSI no está diseñada adecuadamente, no se puede garantizar la precisión de segundo orden para el problema acoplado, aunque cada sub-problema posea tal precisión. En este trabajo se propone un método semi-implícito de segundo orden temporal para este tipo de problemas, y se demuestra dicha precisión a través de rigurosas pruebas numéricas. La última parte de esta tesis se refiere a la eficiencia computacional y la escalabilidad paralela de los métodos desarrollados para la solución numérica de problemas complejos de FSI en supercomputadoras masivamente paralelas. Se presenta un marco paralelo escalable para la solución particionada a través del acoplamiento de múltiples códigos. Se utilizan dos instancias de nuestro software interno para resolver los sub-problemas de fluidos y estructurales. La comunicación entre los solucionadores de física simple se realiza mediante una biblioteca de acoplamiento externa...Postprint (published version

Experimental investigation of inlet distortion effect on performance of a micro gas turbine

An experimental study has been carried out to determine how inlet total-pressure distortion affects the performance of a micro gas turbine. An inlet simulator is designed and developed to produce and measure distortion patterns at the inlet to the gas turbine. An air jet distortion generator (AJDG) is used to produce nonuniform flow patterns and total pressure probes are installed to measure steady-state total-pressure distribution at the inlet. A set of wind tunnel tests have been performed to confirm the fidelity of distortion generator and measuring devices. Tests are carried out with the gas turbine exposed to inlet flow with 60¿deg, 120¿deg, and 180¿deg circumferential distortion patterns with different distortion intensities. The performance of the gas turbine has been measured and compared with that of clean inlet flow case. Results indicate that the gas turbine performance can be affected significantly facing with intense inlet distortions.Peer ReviewedPostprint (published version

An Investigation of the Performance of the ANN Method for Predicting the Base Shear and Overturning Moment Time-Series Datasets of an Offshore Jacket Structure

The primary purpose of the current study was to investigate the performance of artificial neural networks to predict the time series of the water surface level (WSL), base shear, and overturning moment using two types of ANN models: Nonlinear Autoregressive models with exogenous inputs (NARX) and Nonlinear Autoregressive models (NAR). After determining the suitable model, NARX, the possibility of predicting the time series of the base shear and the overturning moment data was investigated by considering the water surface level and time as the multivariable model inputs. A jacket model with a height of 4.55m was fabricated and tested in the 402m-long wave flume of the NIMALA marine laboratory. The jacket was tested at the water depth of 4m and subjected to random waves with a JONSWAP energy spectrum. Three input wave heights were chosen for the tests: 20cm, 23cm, and 28cm. The findings showed that using the NARX neural network is a convenient method to predict the base shear and overturning moment values based on the water surface level data as input values. Finally, after suitable neural network determination, using the NARX neural network, the correlation value (R) for calculating water surface level (WSL), Base Shear, and Overturning Moment were obtained as 0.994, 0.97, and 0.94, respectively

Developing clinical nursing education standards in Iran based on international standards‏

Introduction: Accreditation is one of the most important quality assurance and improvement methods in medical sciences education, especially in the field of nursing clinical education. However, there are not compiled standards in this regard and employing international standards does not seem to be practical. Accordingly, the researchers in this study tried to develop the national standards for accrediting clinical nursing education based on international standards as well as the viewpoints of nursing education experts in Iran. Methods: This study was performed in multiple stages during the years 2004 to 2005. At first, using international standards of nursing education and the views of expert faculty members by Delphi technique, proper standards for the context of Iran were developed. Then, the proposed standards were investigated through a national survey using a designed questionnaire and the ones with more than 70% consensus were approved. At the end, the standards for clinical education were presented separately. Results: Fifty five standards in 5 domains including faculty members and clinical preceptors, students, curriculum, clinical facilities and teaching-learning activities were proposed for the accreditation of clinical nursing education in Iran. Conclusion: The proposed standards had mostly more than 90% of optimum level. However, it seems that the lack of appropriateness of some standards is due to the present situation in nursing education system in Iran. So, these standards were revised or omitted based on experts' comments