Search results

This paper describes the development of a computer finite element method (FEM) model for simulating the temporary earthwork support technique, artificial ground freezing. Specifically, ice‐wall thickness growth and ground movement (due to frost heave and thaw settlement) were evaluated with the use of the finite element software package ABAQUS. Other parameters modelled were obtained from a combination of a priori research and invaluable practitioner experience. Simulation results were then compared with measurements obtained from a live field project to assess model accuracy. Output results obtained from the FEM analyses provided demonstrable evidence of the model’s inherent ability to simulate “realistically” the effects of ground freezing analysis process.

This paper aims to predict aerodynamic heating through the efficient solution of three‐dimensional viscous shock layer (VSL) equations, using axisymmetric analog.

The three‐dimensional VSL equations are written in the curvilinear streamline coordinate system. In these equations, normal momentum equation is replaced by Maslen's pressure relation. In addition to this, axisymmetric analog is implemented along the streamlines through assuming a zero value for circumferential velocity component. In this case, three‐dimensional VSL equations are reduced into an axisymmetric form, which can be solved much easier.

It is demonstrated that the solution of three‐dimensional VSL equations in the curvilinear streamline coordinate system, using axisymmetric analog, has made it possible to predict convective heat fluxes in both windward and leeward regions. Moreover, in comparison with the 3D VSL methods, the present approach dramatically reduces the CPU time of calculations. Comparison with the experimental and numerical data shows a good agreement between both of these data and the present results.

This method is an excellent tool for parametric study and preliminary design of hypersonic vehicles.

This method can predict convective heat flux in the leeward region where other similar methods are not applicable. In addition to this the present method is faster than other methods of solution for the 3D VSL equations.

To design, control and evaluate photovoltaic (PV) systems, an accurate model is required. Accuracy of PV models depends on model parameters. This study aims to use a new algorithm called improved social spider algorithm (ISSA) to detect model parameters.

To improve performance of social spider algorithm (SSA), an elimination period is added. In addition, at the beginning of each period, a certain number of the worst solutions are replaced by new solutions in the search space. This allows the particles to find new paths to get the best solution.

In this paper, ISSA is used to estimate parameters of single-diode and double-diode models. In addition, effect of irradiation and temperature on I–V curves of PV modules is studied. For this purpose, two different modules called multi-crystalline (KC200GT) module and polycrystalline (SW255) are used. It should be noted that to challenge the performance of the proposed algorithm, it has been used to identify the parameters of a type of widely used module of fuel cell called proton exchange membrane fuel cell. Finally, comparing and analyzing of ISSA results with other similar methods shows the superiority of the presented method.

Changes in the spider’s movement process in the SSA toward the desired response have improved the algorithm’s performance. Higher accuracy and convergence rate, skipping local minimums, global search ability and search in a limited space can be mentioned as some advantages of this modified method compared to classic SSA.

Resilience can be of assistance to paramedics in order to maintain their own mental balance in stressful work environments. Since it is not well defined which personality traits are correlated with resilience in these personnel, the purpose of this paper is to explain the relationship between personality traits and levels of resilience.

This cross-sectional study was conducted on paramedics in Eastern Iran through field research. The study participants were selected by convenience sampling method. The data collection instruments included NEO-Five Factor Inventory-Short Form and Connor-Davidson Resilience Scale. The data obtained were also analyzed using descriptive and inferential statistics (correlation and regression analysis) through the SPSS 16.0 software.

A total of 252 paramedics with a mean age of 28.9±5.1 years participated in this study. The personality traits of neuroticism (r=−0.24), openness to experience (r=−0.22), and agreeableness (r=−0.18) were significantly correlated with resilience. In contrast, extraversion (r=0.26) and conscientiousness (r=0.32) were in a significant relationship with resilience. In this respect, the given personality traits could account for 31.5 percent of changes in resilience.

It was concluded that the paramedics with lower scores of neuroticism had higher levels of resilience and they could similarly show better compliance with their work conditions in stressful situations and consequently maintain their mental health.

It is recommended to conduct psychological examinations of personality traits in recruitment and selection stages of medical emergency personnel and to implement psychological interventions for those medical emergency staff with the personality trait of neuroticism.

Resilient paramedics may also perceive less stress and it may be negatively associated with burnout.

The study examined the relationship between personality traits and resiliency in order to clarifying recruitment criteria in emergency medical services.

As demonstrated in the literature, teachers’ knowledge sharing, self-efficacy and creativity display certain levels of cause-and-effect and correlational connections from different perspectives. Nonetheless, few studies, if any, have been reported on the interplay of these three concepts in the context of the language classroom. As such, this study aims to test a structural model of English as a foreign language (EFL) teachers’ knowledge sharing, self-efficacy and creativity and specifically to examine the hypothesis that creativity mediates the relationship between EFL teachers’ knowledge sharing and self-efficacy.

The participants were 384 EFL teachers from different language institutes across Iran. The EFL teachers were selected based on random stratified sampling method. To verify the research hypotheses, a quantitative correlational design was used in the present study. The quantitative data was collected using three questionnaires, and then descriptive and inferential statistics were used to analyze the data. Therefore, we used the EFL teachers’ creativity questionnaire developed by Khany and Boghayeri (2014), knowledge sharing behavior scale by Ramayah et al. (2014) and teachers’ self-efficacy questionnaire by Tschannen-Moran and Hoy (2001). To analyze the data, Pearson correlation and multiple regression were run.

The findings revealed the hypothesized model of relationships among the study variables. The results also confirmed the mediator role of creativity. The implications of the findings in relation to creativity, knowledge sharing and self-efficacy are discussed.

The bulk of research on teacher self-efficacy has concentrated fairly adequately on its relationship with factors such as teachers’ reflective practice, critical thinking, emotional intelligence, personality and student achievement. What seems to be rather missing in this line of research has to do with the exploration of the possible links among knowledge sharing, self-efficacy and creativity as interacting variables, especially in the context of Iran where teachers’ knowledge sharing is lower than expected. More importantly, no previous investigation has tapped into the mediating effect of creativity on the connection between English teachers’ knowledge sharing and self-efficacy.

The purpose of this paper is to investigate the effects of concavity level on performance parameters of a parabolic fin under the influences of natural convection and radiation.

Computational fluid dynamics software (FLUENT) is used for the heat transfer analysis. Optimum fin geometry is searched in order to maximize the heat dissipation from fin to the ambient while minimizing the volume of fin.

The fin profile with concavity level of 2 dissipates 14.92, 17.53, 24.33 and 26.60 percent more heat and uses 34.62, 49.64, 57.66 and 63.09 percent much material compared to the fin with concavity level of 4, 6, 8 and 10, respectively. It is also observed that the amount of heat dissipation per mass considerably increases with increasing concaveness.

The research was carried out for five different concavity levels in the range of 2-10.

The results can be used in passive cooling applications of PV systems. Also, heat sinks for CPU cooling can be redesigned with respect to the results obtained from the research.

In this paper, effects of concavity level on performance parameters of a parabolic fin are investigated for the first time. It is observed from the numerical results that the fin profile with higher concavity levels provides a cheaper and lighter heat dissipation device so it is recommended for the applications where the weight and the cost are primary considerations such as cooling of photovoltaics.

Hepatitis C is one of the major health issues in both developed and developing countries. Hepatitis C virus (HCV) infection is more common in prisoners than in the general population. The purpose of this study was to determine the prevalence of HCV and its associated risk factors in Iranian male prisoners in Tehran.

In this cross-sectional study, the authors investigated the frequency and risk factors of hepatitis C infection among male prisoners in the Great Tehran Prison. Information on risk factors including the length of imprisonment, previous history of imprisonment, history of drug injection, history of tattooing, history of piercing, history of high-risk sex and family history of hepatitis C were extracted from patients’ records. To evaluate HCV status, blood samples were collected and tested.

In this study, 179 participants were included. Nine participants (5.0%, 95% CI, 2.3-9.3) were positive for hepatitis C. HCV infection was not significantly associated with age, marital status, education, previous history of imprisonment, length of imprisonment, piercing and high-risk sex; however, there was a significant association between a history of tattooing and a history of injecting drug use and Hepatitis C.

The prevalence of hepatitis C among male prisoners in Great Tehran Prison was 5% in this study, similar to recent studies on prisoners in Tehran. A history of drug injections as well as tattooing were the most important risk factors for hepatitis C in male prisoners.

A literature review is presented in the subject of construction plant and equipment management (CPeM) to: delineate the subject; consider its development over recent years; and identify principal themes within it. The paper aims to close the gap in knowledge, by using these objectives as a mechanism to observe how research themes relate to primary CPeM functions, and to suggest future research direction.

A thematic review of CPeM academic literature (in the main, refereed journal papers published in English‐speaking countries over the last decade) is undertaken; the nature of identified themes is discussed, for instance, regarding why they might have evolved as they have; and based on the foregone, themes for future research in the field are proffered.

CPeM is found well established within the broader subject of construction management. Eight principal themes are identified, namely plant maintenance; downtime and productivity; optimisation; robotics and automation; health and safety; operators and competence; machine control; and “miscellaneous”.

It is proffered that based on informational/technological advancements coupled with growing environmental/financial pressures, future CPeM research will strive to facilitate even greater plant reliability and safer modes of working. It is suggested that “optimum production methods” and “minimal resource consumption” will become inherent theme goals.

This is the first time that CPeM research has been consolidated and reviewed for publication in this manner.

The paper aims to analyse the effect of acid hydrolysis on the chemical composition and the biological activities of Rubia tinctorum collected from the south of Tunisia. It proposes to clarify the relationship between alizarin content and the antioxidant and antimicrobial activities of Rubia extract.

The paper opted for analytical tools (HPLC) and the in-vitro study of biological activities, namely, the antioxidant activity which is evaluated using the radical scavenging assay (ABTS) and ferric reducing power assay (FRAP); the antimicrobial activity is tested using the wells agar diffusion method.

The paper provides information about the positive effect of acid hydrolysis, namely, the enhancement of alizarin content in the extract which has increased its antioxidant and antimicrobial activities.

This paper fulfils an identified need to study the relationship between the chemical composition, biological activities and colour enhancement.

An emerging technology in the primary stages of its life cycle is the blockchain. This research paper aims to evaluate the preparedness of hospitals in using blockchain technology in their electronic health record (EHR) systems.

In the initial stage, 15 criteria relating to preparedness in using blockchain in EHR systems were identified from the literature and divided into five criteria, namely, technological, legal, financial, environmental and organizational. Then, 17 experts from various specialized fields were invited to form expert panels. After validating the criteria identified by the expert panels, the weights of the criteria were determined through the fuzzy best-worst multicriteria decision-making method. Following that, the preparedness of ten selected hospitals in Tehran to use blockchain in their EHR systems was assessed via the weighted aggregated sum product assessment method. Finally, using sensitivity analysis and examining different scenarios, the robustness of the results of the proposed approach was validated.

According to expert judgments, the legal criterion (32%) was deemed the most important factor in the preparedness to use blockchain in EHR systems followed by technological (28%), financial (17%), organizational (13%) and environmental (9%) criteria. A sensitivity analysis showed that the proposed approach offers good strength and robustness in evaluating the selected hospitals.

This study can be useful in developing knowledge in the field of technology management for evaluating blockchain implementation in the health-care industry using a novel, coherent and robust approach. In addition, the proposed approach provides comprehensive insight for decision-makers on assessing preparedness in deploying blockchain technology in EHR systems.