• Journal of Industrial and Engineering Chemistry
• /
• v.68
• /
• pp.406-415
• /
• 2018

Here, as-synthesized $Fe_3O_4$ nanoparticles were incorporated into the zeolitic imidazolate framework (ZIF-8) lattice to activate sodium percarbonate (SPC) for degradation of methylene blue (MB). The reaction rate constant of $Fe_3O_4@ZIF-8/SPC$ process ($0.0632min^{-1}$) at acidic conditions (pH = 3) was more than six times that of the $Fe_3O_4/SPC$ system ($0.009min^{-1}$). Decreasing the solute concentration, along with increasing SPC concentration and $Fe_3O_4@ZIF-8$ nanocomposite (NC) dosage, favored the catalytic degradation of MB. The $Fe_3O_4@ZIF-8$ NC after fifteen consecutive treatment processes showed the excellent stability with a negligible drop in the efficiency of the system (<10%). The reaction pathway was obtained via GC-MS analysis.

• Structural Monitoring and Maintenance
• /
• v.6 no.1
• /
• pp.33-46
• /
• 2019

In present study, Operational Modal Analysis (OMA) was employed to carry out the dynamic and vibration analysis of the threshing unit of the combine harvester thresher as a mechanical component. The main study is to find the causes of vibration and to decrease it to enhance the lifetime and efficiency of the threshing unit. By utilizing OMA, structural modal parameters such as mode shapes, natural frequencies, and damping ratio was calculated. The combine harvester was excited by engine to vibrate different parts and accelerometer sensor collected acceleration signals at different speeds, and OMA was utilized by nonparametric and frequency analysis methods to obtain modal parameters while vibrating in real working conditions. Afterwards, finite element model was designed from the thresher and updated using the data obtained from the modal analysis. Using the conducted analyses, it was specified that proximity of the thresher pass frequency to one of the natural frequencies (16.64 Hz) was the most important effect of vibration in the thresher. Modification process of the structure was carried out by increasing mass required for changing the natural frequency location of the first mode to 12.4 Hz in order to reduce resonance and vibration of the thresher.

• Geomechanics and Engineering
• /
• v.27 no.5
• /
• pp.511-525
• /
• 2021

In the design of underground excavation, the shear strength (SS) is a key characteristic. It describes the way the rock material resists the shear stress-induced deformations. In general, the measurement of the parameters related to rock shear strength is done through laboratory experiments, which are costly, damaging, and time-consuming. Add to this the difficulty of preparing core samples of acceptable quality, particularly in case of highly weathered and fractured rock. This study applies rock index test to the indirect measurement of the SS parameters of shale. For this aim, two efficient artificial intelligence methods, namely (1) adaptive neuro-fuzzy inference system (ANFIS) implemented by subtractive clustering method (SCM) and (2) support vector regression (SVR) optimized by Harmony Search (HS) algorithm, are proposed. Note that, it is the first work that predicts the SS parameters of shale through ANFIS-SCM and SVR-HS hybrid models. In modeling processes of ANFIS-SCM and SVR-HS, the results obtained from the rock index tests were set as inputs, while the SS parameters were set as outputs. By reviewing the obtained results, it was found that both ANFIS-SCM and SVR-HS models can provide acceptable predictions for interlocking and friction angle parameters, however, ANFIS-SCM showed a better generalization capability.

• Structural Engineering and Mechanics
• /
• v.85 no.3
• /
• pp.369-379
• /
• 2023

Reliability-Based Design Optimization (RBDO) is an appropriate framework for obtaining optimal designs by taking uncertainties into account. Large-scale problems with implicit limit state functions and problems with discrete design variables are two significant challenges to traditional RBDO methods. To overcome these challenges, this paper proposes a hybrid method to perform RBDO of structures that links Firefly Algorithm (FA) as an optimization tool to advanced (finite element) reliability methods. Furthermore, the Genetic Algorithm (GA) and the FA are compared based on the design cost (objective function) they achieve. In the proposed method, Weighted Simulation Method (WSM) is utilized to assess reliability constraints in the RBDO problems with explicit limit state functions. WSM is selected to reduce computational costs. To performing RBDO of structures with finite element modeling and implicit limit state functions, a First-Order Reliability Method (FORM) based on the Direct Differentiation Method (DDM) is utilized. Four numerical examples are considered to assess the effectiveness of the proposed method. The findings illustrate that the proposed RBDO method is applicable and efficient for RBDO problems with discrete and continuous design variables and finite element modeling.

• Bulletin of the Korean Mathematical Society
• /
• v.59 no.4
• /
• pp.917-928
• /
• 2022

Let R be a commutative Noetherian ring and I an ideal of R. In this paper, we study colocalization of generalized local homology modules. We intend to establish a dual case of local-global principle for the finiteness of generalized local cohomology modules. Let M be a finitely generated R-module and N a representable R-module. We introduce the notions of the representation dimension r^I(M, N) and artinianness dimension a^I(M, N) of M, N with respect to I by r^I(M, N) = inf{i ∈ ℕ₀ : H^I_i(M, N) is not representable} and a^I(M, N) = inf{i ∈ ℕ₀ : H^I_i(M, N) is not artinian} and we show that a^I(M, N) = r^I(M, N) = inf{r^IR_𝔭 (M_𝔭,𝔭N) : 𝔭 ∈ Spec(R)} ≥ inf{a^IR_𝔭 (M_𝔭,𝔭N) : 𝔭 ∈ Spec(R)}. Also, in the case where R is semi-local and N a semi discrete linearly compact R-module such that N/∩_t>0I^tN is artinian we prove that inf{i : H^I_i(M, N) is not minimax}=inf{r^IR_𝔭 (M_𝔭,𝔭N) : 𝔭 ∈ Spec(R)＼Max(R)}.

• Korean Journal of Exercise Nutrition
• /
• v.25 no.4
• /
• pp.17-23
• /
• 2021

[Purpose] This study aimed to investigate the effect of education based on the health belief model on the physical activity of the staff of the University of Medical Sciences. [Methods] This semi-experimental study was conducted on 130 university staff aged 25-50 years from the Hamadan University of Medical Sciences. Inclusion criteria were having at least 1 year of work experience, lack of acute and chronic physical and mental illnesses, and not using drugs that affect physical activity. The samples were randomly divided into two groups. The experimental group received three training sessions based on the health belief model. Before and 2 months after training, the control and experimental groups were evaluated via the following questionnaires: (1) demographic information questionnaire, (2) Health Belief Model Questionnaire, and (3) International Physical Activity Questionnaire. Finally, data were analyzed statistically. [Results] The training process resulted in a significant increase in the mean scores of the health belief model constructs in the experimental group, but changes in the control group were not significant. Self-efficacy was the strongest predictor of physical activity. [Conclusion] The health belief model is a useful model for improving individuals' understanding of the benefits of physical activity.

• Safety and Health at Work
• /
• v.14 no.2
• /
• pp.153-162
• /
• 2023

Background: Job safety analysis (JSA) is a popular technique for hazard identification and risk assessment in workplaces that has been applied across a wide range of industries. This systematic review was conducted to answer four main questions regarding JSA: (1) which sectors and areas have used JSA? (2) What has been the aim of employing JSA? (3) What are the shortcomings of JSA? (4) What are the new advances in the field of JSA? Methods: Three main international databases were searched: SCOPUS, Web of Science, and PubMed. After screening and eligibility assessment, 49 articles were included. Results: Construction industries have used JSA the most, followed by process industries and healthcare settings. Hazard identification is the main aim of JSA, but it has been used for other purposes as well. Being time-consuming, the lack of an initial list of hazards, the lack of a universal risk assessment method, ignoring hazards from the surrounding activities, ambiguities regarding the team implementing JSA, and ignorance of the hierarchy of controls were the main shortcomings of JSA based on previous studies. Conclusion: In recent years, there have been interesting advances in JSA making attempts to solve shortcomings of the technique. A seven-step JSA was recommended to cover most shortcomings reported by studies.

• Safety and Health at Work
• /
• v.7 no.4
• /
• pp.317-321
• /
• 2016

Background: This study was conducted with aim of providing an overview of the current status of occupational health services and identifying the most common harmful agents at workplaces of Iranian self-employed enterprises (Nano-Scale Enterprises). Methods: A cross-sectional study was performed among a random sample including 1,758 employees engaging in self-employed enterprises with 5 and less employees. Results: Coverage of occupational health surveillance was very poor, annual health examinations were been conducted only for 64 (3.64%) of males and 31 (1.76%) of females, and occupational health trainings were not included of the services at all. Personal Protective Equipment were available in 462 (26.3%) of the enterprises. only in 0.4% of the enterprises working processes were been equipped by a local exhaust ventilation system. Difficult postures were the most common (81.5%) adverse working conditions. Conclusion: This study revealed a poor level of the implementation of occupational health services in Iranian self-employed enterprises. Based on the findings, providing basic training on the occupational health, more enforcing in conduction of health examinations and providing PPE, and taking appropriate strategies aimed at eliminating or minimizing work environment harmful agents are the major factor that should be considered to improve the level of occupational health services among the studied enterprises.

• Asian Pacific Journal of Cancer Prevention
• /
• v.14 no.12
• /
• pp.7283-7288
• /
• 2013

Background: Tobacco use among adolescents is a major public health concern, and identifying predictors of smoking is necessary for planning prevention programs. The present study examined the relationship between refusal self efficacy, self esteem, smoking refusal skills and water pipe (hookah) smoking among Iranian male adolescents. Materials and Methods: A cross-sectional study was conducted with 380 Iranian male adolescents aged between 15-19 years selected by multistage sampling. The participants completed an anonymous, voluntary, self-report questionnaire. Variables independently associated with water pipe (WP) smoking were identified by multiple logistic regression analysis. Results: The mean age of the participants was $16.7{\pm}1.3$ years. The prevalence of WP smoking was 17.3%. Logistic regression analysis revealed that knowledge (OR=0.56; 95% CI: (0.37-0.79), attitude (OR=0.69; 95% CI: (0.52-0.89), self esteem (OR=0.67; 95% CI: (0.55-0.82), smoking refusal skills (OR=0.73; 95% CI: (0.55-0.87), and self efficacy (OR=.82; 95% CI: (0.61-0.93) were all signifcant prediting facotrs for adolescents WP smoking. Conclusions: The findings have implications for public health interventions. Indeed, self efficacy and smoking refusal skills should be considered when developing tailored measures for the prevention of WP smoking among adolescents.

• Industrial Engineering and Management Systems
• /
• v.14 no.3
• /
• pp.221-235
• /
• 2015

Risk assessment is an important phase of risk management. It is the stage in which risk is measured thoroughly to achieve effective management. Some factors such as probability and impact of risk have been used in the literature related to construction projects. Because in high-rise projects safety issues are paramount, this study has tried to develop a quantifying technique that takes into account three factors: probability, impact and Safety Performance Index (SPI) where the SPI is defined as the capability of an appropriate response to reduce or limit the effect of an event after its occurrence with regard to safety pertaining to a project. Regarding risk-related literatures which cover an uncertain subject, the proposed method developed in this research is based on a fuzzy logic approach. This approach entails a questionnaire in which the subjectivity and vagueness of responses is dealt with by using triangular fuzzy numbers instead of linguistic terms. This method returns a Risk Critical Point (RCP) on a zoning chart that places risks under categories: critical, critical-probability, critical-impact, and non-critical. The high-rise project in the execution phase has been taken as a case study to confirm the applicability of the proposed method. The monitoring results showed that the RCP method has the inherent ability to be extended to subsequent applications in the phases of risk response and control.