Search results

Hexagonal honeycombs with meso-metric cell size show excellent load bearing and energy absorption potential, which make them attractive in many applications. However, owing to their bend-dominated structure, honeycombs are susceptible to deformation localization. The purpose of this study is to provide insight about shear band propagation in struts of 3D-printed honeycombs and its relation to the achieved macroscopic mechanical behavior.

Hexagonal honeycombs and unit cell models are 3D-printed by fused deposition modeling (FDM). The samples are exposed to compression loading and digital image correlation technique and finite element analyses are incorporated.

It is found that the strain contours, which are obtained by finite element, are in agreement with experimental measurements made by DIC. In addition, three stages of shear band propagation in struts of 3D-printed honeycombs are illustrated. Then the correlation between shear band propagation stages and the achieved macroscopic mechanical responses is discussed in detail.

For the first time, a hierarchical activation of different modes of shear band propagation in struts of a 3D-printed honeycomb is reported. This information can be of use for designing a new generation of honeycombs with tailor-made localization and energy absorption potential.

The aim of this paper is to predict and minimize the risks of oil, gas and petrochemical projects. Besides, reducing the likelihood of occurrence and minimizing risks impact on the projects to reduce the probable costs and improve the economic situation is another purpose of this paper.

This paper provides a fuzzy Decision-Making Trial and Evaluation Laboratory (DEMATEL) – a technique that assist to solve decision-making problems – and IP (Impact & Probability) table methods to identify and analyze critical risks in energy projects, and then fuzzy Binary Logistic Regression (BLR) in order to predict the probability of each level of risk for more efficient risk management in projects. Furthermore, in this paper, the fuzzy BLR (FBLR) is optimized such that the probability of a high level of risk for the implementation of the project has been minimized using meta-heuristic algorithm.

The results from the point of view of experts show that combination of fuzzy DEMATEL with FBLR approach as well as using SA algorithm, in order to optimize the high level of risks, can provide a smart approach to managing risks with more success.

The application of the proposed method is illustrated via a real data set from energy projects.

We propose combined fuzzy DEMATEL and FBLR methods to predict and optimize the risks of the energy projects, which is the innovation of this paper.

This qualitative study sought to explore how Iranian English language professors used social media network Telegram in their classes and what possibilities and constraints they experienced with regard to classroom interactions and university education, and how they rethought the use of social media network Telegram.

Data were collected through written reflective exercises and semi-structured interviews. Furthermore, data were analyzed based on three moments of critical hermeneutics: a moment of social-historical analysis, a moment of formal analysis and a moment of interpretation-reinterpretation.

The analysis of the data led to four themes: a dialogic classroom, the critical awareness of power-relations, the critical reflection on the experiences of the classroom and digital inequality. In fact, the participants pointed out that using social media network Telegram could lead to the persuasive discourse and multiplicity of voices as opportunities for sharing knowledge and distributing powers.

Indeed, the present study addressed the learning processes resulted from using social media network Telegram rather than the product and outcome that were mainly addressed by the previous studies by considering three levels of descriptions, which included micro-level of the learner and teacher interaction, meso-level of the processes of educational institutions and macro-level of wider cultural and societal contexts.

Technology is named as the most important element of creating the competitive edge in today’s turbulent environment and a key factor of survival in technology-intensive industries. Oil and gas industry is one of the most important, complex, and technology-driven amongst the global industries. “The purpose of this study is to highlight the role of the technology in the the global oil game and argue that in order to survive and maintain the competitive advantage, players need to follow technological advancements closely and consider technology as the critical factor in their business models.” Thus, the aim is to answer the question: does technology have an impact on the business model innovation in the oil and gas industry?

In this paper, the authors conduct an in-depth review of previous studies of oil and gas industry, main players, the role and evolution of technology in each player’s business model and present future challenges and trends of the industry.

Theoretically, the results of shows that the relation between the technology and business model in oil and gas industry is defined as a two way interaction which is in line with the theory presented by Baden–Fuller and Haefliger (2013); thus it helps the robustness of the theory as well. We argue that technology gained a “game changer” status in the oil and gas industry, beside all the fundamental premises on which business model is built on, having technology seems to be the key element of survival and the ability to develop in-house or have access to the latest ones in the right time can help the market share, revenue and leadership status. this key element can reinforce other pillars of powers in the oil and gas industry.

Most of the research in the oil and gas industry are practical, focusing on a specific technology, clean energy issues, regulations, and policies, etc. There exist few studies that present the theoretical issues in the industry or test the theories to see if this important industry falls within them or not. As follows, this study is about to address this gap and observe the dynamics in the oil and gas industry with an academic lens.

It has been suggested that there is a link between the dietary intake of certain nutrients and the risk of prostate cancer. The aim of this study is to examine the associations between dietary intakes of all nutrients and the risk of prostate cancer in Kermanshah.

This case-control study was conducted in Kermanshah, a province in the west of Iran in November of 2016. The sample consisted of 50 patients with confirmed prostate cancer, and 150 healthy men who matched in age with these cases and did not have any symptoms of prostate disorder were chosen as controls. Dietary intakes were collected by a semi-quantitative food frequency questionnaire that contained 147 food items and were then analyzed by Nutritionist 4 software.

After adjustment for potential confounding factor, highest tertile compared to lowest tertile of dietary vitamin E intake [odds ratio (OR) = 0.21; 95% confidence interval (CI) = 0.05-0.89], lycopene intake (OR = 0.11; 95% CI = 0.01-0.86) and magnesium intake (OR = 0.02; 95% CI = 0.01-0.55) had a protective effect on the incidence of prostate cancer. However, there were no associations between dietary intakes of fiber, vitamin A, vitamin D, vitamin B₁₂, folate and calcium with prostate cancer.

The finding suggests that the dietary intakes of vitamin E, lycopene and magnesium could decrease the risk of prostate cancer. Nevertheless, dietary intake of other nutrients such as fiber, calcium, vitamins D, A, B₁₂ and folate was not associated with prostate cancer.

In the case of Iran, about 19 years have passed since the announcement of general energy policies. Policies adopted in the past included too many approaches and goals for the energy sector that some of them are in conflict with each other and their simultaneous implementation was impossible. Therefore, many of the expected goals of these policies have not been achieved. It is very important to adopt an appropriate approach that is compatible with the country’s characteristics and can steer energy policies. Therefore, this study aims to adopt an appropriate approach for the country’s energy sector according to the conditions and needs of the country.

A participatory scenario technique is designed and used to develop plausible projections in the case of Iran’s energy futures. Based on the proposed methodology, the research process starts with data gathering through interviews and national plans analysis. Then, findings were used as inputs to a simulation-based scenario development process. Scenarios are developed based on Monte Carlo simulation via cross-impact analysis technique purified based on expert judgments.

In this paper, to recognize Iran’s general approach to energy in the next 20 years, driving forces of change were introduced and used as input for the scenario development phase. Results showed sanctions play a significant role in Iran’s energy future and determine the directions of other driving forces. For renewable energy, it was proposed to increase the renewable share in Iran’s electricity generation mix to 5% of the total installed capacity. In the case of fossil fuel extraction, the maximum efficient rate was proposed for both oil and natural gas national production strategy.

This research is novel both in terms of application and theory. A new participatory scenario development method is used using simulations that are equipped based on experts’ judgments. Also from the practical perspective, this research targeted a future-oriented challenging problem to initialize national policy in a resource-rich developing economy (i.e. Iran).

The purpose of this paper is to investigate the effect of TiO₂ nanoparticle content on the corrosion behavior of Ni‐Cr/TiO₂ nanocomposite coatings applied by pulse‐reverse electroplating.

Ni‐Cr/TiO₂ nanocomposite coatings with various contents of TiO₂ nanoparticles were electrodeposited by pulse‐reverse method from a bath containing TiO₂ nanoparticles to be codeposited and citric acid as the complexing agent. The surface morphology and the composition of coatings were studied by scanning electron microscopy (SEM) equipped by energy dispersive X‐ray system (EDS). The corrosion performance of coatings in the 0.5 M NaCl as a corrosive solution was investigated by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) methods.

It was found that the surface of Ni‐Cr/TiO₂ nanocomposite coatings showed a finer structure that was more uniform and compact in appearance than was that of Ni‐Cr coatings. The incorporation of TiO₂ nanoparticles in the alloy coating matrix improved the corrosion performance of the coatings and the higher content of nanoparticles gave better corrosion resistance.

Applying the Ni‐Cr coatings by the pulse‐reverse plating method eliminated cracks that were a problem in the Ni‐Cr alloy coating structure. Furthermore, the corrosion resistance was improved by the addition of TiO₂ nanoparticles to the alloy matrix. This paper reports the optimum plating conditions that gave the better corrosion performance.

This study aims to use frequency response analysis, a powerful tool to detect the location and types of transformer winding faults. Proposing an effective intelligent approach for interpreting the frequency responses is the most crucial problem of this method and has created many challenges.

Heat maps based on appropriate statistical indices have been supplied to depict the variations in the frequency responses associated with each fault type, fault location and fault extent along the windings. Also, after analyzing the results of artificial neural network (ANN) techniques, the generalized regression neural network method is introduced as the most effective solution for the classification of transformer winding faults.

Using a comparative approach, the performance of the used indices and ANN techniques are evaluated. The results showed the proper performance of Lin’s concordance coefficient (LCC) index and the amplitude (Amp) part of the frequency response. The proposed fitting percentage (FP) index can assist the intelligent classifiers in diagnosing the radial deformation (RD) fault with the highest accuracy considering all frequency response components in the classification procedure of winding faults.

Various ANN techniques are used to detect and determine the type of four important faults of transformer winding, i.e. axial displacement, RD, disc space variation and short circuit. Various statistical indices, such as cross-correlation factor, LCC, standard difference area, sum of errors, normalized root-mean-square deviation and FP, are used to extract the features of the frequency responses to consider as the ANN inputs. In addition, different components of the frequency response, such as Amp, argument, real and imaginary parts are examined in this paper. To implement the proposed procedure, step by step, various types of winding faults with different locations and extents are applied on the 20 kV winding of a 1.6 MVA distribution transformer.

Contributions have been made in identifying and diagnosing transformer winding defects through the use of appropriate algorithms for future research.

In the context of architecture education, design studio projects usually start with “research” on the design theme and the context, but often there is no strong link between this research and its application in the project and the resultant design product. This paper explores strategies which link knowledge acquisition and knowledge application in design studio teaching and learning.

These strategies have been applied in several design studios and master’s theses and involve sixteen years of research by the author through observation, surveys and analysis of student work.

The results show that these strategies are not limited to the design studio, with more than half of them (eight out of fourteen) also applicable in theoretical subjects that sit outside the design studio unit and generate knowledge of relevance to studio projects. As such, the paper advocates for a multi-level approach involving the following: course design and curriculum development, teaching and learning pedagogies and organizational decisions regarding the deployment of staff as for collaborative team-based teaching.

The results also recognize the relevance of problem-based and project-based learning to the broader higher education context and its dependence on a collaborative approach.

This paper which synthesizes this work contributes to the literature on architecture pedagogy, specifically that related to the integration of theoretical and practical subjects.

Life conditions for most slum dwellers are deplorable, with poor socio-economic status and high rates of malnutrition and communicable diseases. Studies have shown lower intake of many nutrients in such people, but no study yet has checked the quality of diet using Healthy Eating Index (HEI) in them. This study aims to assess the quality of diet among slum dwellers of Tehran using the HEI-2015.

This cross-sectional study was conducted among 300 slum dwellers from two slums located on the border of Tehran city which is the capital of Iran. Stratified random sampling technique was used to select subjects for this study. Data on socioeconomic characteristics and 24-hours dietary recalls were obtained through face-to-face interviews with the respondents by trained personnel.

The overall diet quality of the respondents was poor, with a mean HEI score of 40.9 ± 23.7. About 84% of the participants had low overall HEI scores. A significant relation was seen in the following: the HEI and educational level (p = 0.044); the HEI and employment status (p = 0.001); and the HEI and chronic diseases (p = 0.049). There was no significant difference between the mean HEI score and marital status, welfare status and addiction status. From the findings, the diet of most of these slum dwellers needs modification. Therefore, taking measures to reduce slum dwelling and to improve the nutritional intake of this study population is needed.

The study was approved by the Ethics Committee of Tehran University of Medical Sciences, Tehran, Iran, and written informed consent was obtained from all participants.