THE BUCHSTAB'S FUNCTION AND THE OPERATIONAL TAU METHOD

Aliabadi, M.Hosseini 한국전산응용수학회 2000 The Korean journal of computational & applied math Vol.7 No.3

In this article we discuss some aspects of operational Tau Method on delay differential equations and then we apply this method on the differential delay equation defined by $\omega(u)\;=\frac{1}{u}\;for\;1\lequ\leq2$ and $(u\omega(u))'\;=\omega(u-1)\;foru\geq2$, which was introduced by Buchstab. As Khajah et al.[1] applied the Recursive Tau Method on this problem, they had to apply that Method under the Mathematica software to get reasonable accuracy. We present very good results obtained just by applying the Operational Tau Method using a Fortran code. The results show that we can obtain as much accuracy as is allowed by the Fortran compiler and the machine-limitations. The easy applications and reported results concerning the Operational Tau are again confirming the numerical capabilities of this Method to handle problems in different applications.

Human Error Probability Determination in Blasting Process of Ore Mine Using a Hybrid of HEART and Best-Worst Methods

Aliabadi, Mostafa Mirzaei,Mohammadfam, Iraj,Soltanian, Ali Reza,Najafi, Kamran Occupational Safety and Health Research Institute 2022 Safety and health at work Vol.13 No.3

Background: One of the important actions for enhancing human reliability in any industry is assessing human error probability (HEP). The HEART technique is a robust tool for calculating HEP in various industries. The traditional HEART has some weaknesses due to expert judgment. For these reasons, a hybrid model is presented in this study to integrate HEART with Best-Worst Method. Materials Method: In this study, the blasting process in an iron ore mine was investigated as a case study. The proposed HEART-BWM was used to increase the sensitivity of APOA calculation. Then the HEP was calculated using conventional HEART formula. A consistency ratio was calculated using BWM. Finally, for verification of the HEART-BWM, HEP calculation was done by traditional HEART and HEART-BWM. Results: In the view of determined HEPs, the results showed that the mean of HEP in the blasting of the iron ore process was 2.57E-01. Checking the full blast of all the holes after the blasting sub-task was the most dangerous task due to the highest HEP value, and it was found 9.646E-01. On the other side, obtaining a permit to receive and transport materials was the most reliable task, and the HEP was 8.54E-04. Conclusion: The results showed a good consistency for the proposed technique. Comparing the two techniques confirmed that the BWM makes the traditional HEART faster and more reliable by performing the basic comparisons.

A MATRIX FORMULATION OF THE TAU METHOD FOR FREDHOLM AND VOLTERRA LINEAR INTEGRO-DIFFERENTIAL EQUATIONS

Aliabadi, M.-Hosseini,Shahmorad, S. 한국전산응용수학회 2002 The Korean journal of computational & applied math Vol.9 No.2

In this paper we obtain the matrix Tau Method representation of a general boundary value problem for Fredholm and Volterra integro-differential equations of order $\nu$. Some theoretical results are given that simplify the application of the Tau Method. The application of the Tau Method to the numerical solution of such problems is shown. Numerical results and details of the algorithm confirm the high accuracy and user-friendly structure of this numerical approach.

Barriers to Health Service Utilization Among Iranian Female Sex Workers: A Qualitative Study

Asadi-AliAbadi, Mehran,Abolghasemi, Jamileh,Rimaz, Shahnaz,Majdzadeh, Reza,Rostami-Maskopaee, Fereshteh,Merghati-Khoei, Effat The Korean Society for Preventive Medicine 2018 Journal of Preventive Medicine and Public Health Vol.51 No.2

Objectives: In most countries around the world, sex work is an illegal activity. Female sex workers (FSWs) in Iran hide their identities, and they are known to be a hard-to-reach population. Despite free access to HIV testing, fewer than half of FSWs receive HIV testing. The purpose of this study was to characterize the reasons for which FSWs do not seek testing at drop-in centers (DICs) and voluntary counseling and testing (VCT) centers in Iran. Methods: A qualitative study was conducted in 2016. The participants were 24 FSWs who received services at VCT centers and DICs for vulnerable females in the north of Iran and 9 males who were the clients of FSWs. In this study, we made use of purposive sampling and carried out a thematic analysis. Results: We found 4 major and 6 minor themes. The major themes were: fear of being infected (with HIV), stigma, indifference, and knowledge. Conclusions: Despite the significant efforts made by the government of Iran to establish and expand DICs for vulnerable females, the number of FSWs receiving services at these centers has not been very considerable. Consequently, by introducing and implementing training programs for peer groups, it may be possible to take steps toward establishing strategic programs for the control and prevention of HIV/AIDS.

Analysis of the severity of occupational injuries in the mining industry using a Bayesian network

Mostafa Mirzaei Aliabadi,Hamed Aghaei,Omid Kalatpuor,Ali Reza Soltanian,Asghar Nikravesh 한국역학회 2019 Epidemiology and Health Vol.41 No.-

OBJECTIVES: Occupational injuries are known to be the main adverse outcome of occupational accidents. The purpose of the current study was to identify control strategies to reduce the severity of occupational injuries in the mining industry using Bayesian network (BN) analysis. METHODS: The BN structure was created using a focus group technique. Data on 425 mining accidents was collected, and the required information was extracted. The expectation-maximization algorithm was used to estimate the conditional probability tables. Belief updating was used to determine which factors had the greatest effect on severity of accidents. RESULTS: Based on sensitivity analyses of the BN, training, type of accident, and activity type of workers were the most important factors influencing the severity of accidents. Of individual factors, workers’ experience had the strongest influence on the severity of accidents. CONCLUSIONS: Among the examined factors, safety training was the most important factor influencing the severity of accidents. Organizations may be able to reduce the severity of occupational injuries by holding safety training courses prepared based on the activity type of workers.

Effects of human and organizational deficiencies on workers’ safety behavior at a mining site in Iran

Mostafa Mirzaei Aliabadi,Maryam SeyedTabib 한국역학회 2018 Epidemiology and Health Vol.40 No.-

OBJECTIVES:Throughout the world, mines are dangerous workplaces with high accident rates. According to the Statistical Center of Iran, the number of occupational accidents in Iranian mines has increased in recent years. This study investigated and analyzed the human and organizational deficiencies that influenced Iranian mining accidents. METHODS: In this study, the data associated with 305 mining accidents were analyzed using a systems analysis approach to identify critical deficiencies in organizational influences, unsafe supervision, preconditions for unsafe acts, and workers’ unsafe acts. Partial least square structural equation modeling (PLS-SEM) was utilized to model the interactions among these deficiencies. RESULTS: Organizational deficiencies had a direct positive effect on workers’ violations (path coefficient, 0.16) and workers’ errors (path coefficient, 0.23). The effect of unsafe supervision on workers’ violations and workers’ errors was also significant, with path coefficients of 0.14 and 0.20, respectively. Likewise, preconditions for unsafe acts had a significant effect on both workers’ violations (path coefficient, 0.16) and workers’ errors (path coefficient, 0.21). Moreover, organizational deficiencies had an indirect positive effect on workers’ unsafe acts, mediated by unsafe supervision and preconditions for unsafe acts. Among the variables examined in the current study, organizational influences had the strongest impact on workers’ unsafe acts. CONCLUSIONS: Organizational deficiencies were found to be the main cause of accidents in the mining sector, as they affected all other aspects of system safety. In order to prevent occupational accidents, organizational deficiencies should be modified first.

Temperature nonuniformity management in heat sinks through applying counterflow design complex minichannels

Morteza Khoshvaght-Aliabadi,Amir Feizabadi,Aida Salimi,Mohammad Mehdi Rashidi 한국화학공학회 2022 Korean Journal of Chemical Engineering Vol.39 No.6

Thanks to the electronic industrial revolution, miniaturization, which is a trend to manufacture smallerproducts and devices, has been extended to hardware components. In these devices, the heat flux magnitude increasesdue to the smaller surface area. Therefore, heat dissipation and temperature uniformity are crucial issues that must bemanaged precisely, otherwise destructive effects on system performance and device lifespan are unavoidable. Heat sinksare efficient equipment utilized to solve these dire consequences. In this study, to improve the temperature uniformityof electronic components, novel minichannels, including straight walls with wavy fins (SWS) and wavy walls withstraight fins (WSW), were examined with counter-flow patterns. The observations imply that these novel minichannelsbring 18.1-40.3% decrease of the base temperature under the heat flux of 100 kW m2. It is also revealed that using thenovel minichannels can increase the temperature uniformity up to 93.1%. In addition, overall hydrothermal performancecan be enhanced as high as 1.64 under the pumping power of 0.0374W. It was also found that the use of WSWmodels leads to lower magnitudes of pumping power compared to SWS models. It is concluded that applying the proposedminichannels could be an efficient approach to manage temperature non-uniformity in heat sinks.

Barriers to Health Service Utilization Among Iranian Female Sex Workers: A Qualitative Study

Mehran Asadi-AliAbadi,Jamileh Abolghasemi,Shahnaz Rimaz,Reza Majdzadeh,Fereshteh Rostami-Maskopaee,Effat Merghati-Khoei 대한예방의학회 2018 Journal of Preventive Medicine and Public Health Vol.51 No.2

Objectives: In most countries around the world, sex work is an illegal activity. Female sex workers (FSWs) in Iran hide their identities, and they are known to be a hard-to-reach population. Despite free access to HIV testing, fewer than half of FSWs receive HIV testing. The purpose of this study was to characterize the reasons for which FSWs do not seek testing at drop-in centers (DICs) and voluntary counseling and testing (VCT) centers in Iran. Methods: A qualitative study was conducted in 2016. The participants were 24 FSWs who received services at VCT centers and DICs for vulnerable females in the north of Iran and 9 males who were the clients of FSWs. In this study, we made use of purposive sampling and carried out a thematic analysis. Results: We found 4 major and 6 minor themes. The major themes were: fear of being infected (with HIV), stigma, indifference, and knowledge. Conclusions: Despite the significant efforts made by the government of Iran to establish and expand DICs for vulnerable females, the number of FSWs receiving services at these centers has not been very considerable. Consequently, by introducing and implementing training programs for peer groups, it may be possible to take steps toward establishing strategic programs for the control and prevention of HIV/AIDS.

A MATRIX FORMULATION OF THE TAU METHOD FOR FREDHOLM AND VOLTERRA LINEAR INTEGRO-DIFFERENTIAL EQUATIONS

M. Hosseini AliAbadi,S. Shahmorad 한국전산응용수학회 2002 Journal of applied mathematics & informatics Vol.9 No.2

In this paper we obtain the matrix Tau Method representation of a general boundary value problem for Fredholm and Volterra integro-differential equations of order $\nu$. Some theoretical results are given that simplify the application of the Tau Method. The application of the Tau Method to the numerical solution of such problems is shown. Numerical results and details of the algorithm confirm the high accuracy and user-friendly structure of this numerical approach. In this paper we obtain the matrix Tau Method representation of a general boundary value problem for Fredholm and Volterra integro-differential equations of order $\nu$. Some theoretical results are given that simplify the application of the Tau Method. The application of the Tau Method to the numerical solution of such problems is shown. Numerical results and details of the algorithm confirm the high accuracy and user-friendly structure of this numerical approach.

Individual Fit Testing of Hearing Protection Devices Based on Microphone in Real Ear

Biabani, Azam,Aliabadi, Mohsen,Golmohammadi, Rostam,Farhadian, Maryam Occupational Safety and Health Research Institute 2017 Safety and health at work Vol.8 No.4

Background: Labeled noise reduction (NR) data presented by manufacturers are considered one of the main challenging issues for occupational experts in employing hearing protection devices (HPDs). This study aimed to determine the actual NR data of typical HPDs using the objective fit testing method with a microphone in real ear (MIRE) method. Methods: Five available commercially earmuff protectors were investigated in 30 workers exposed to reference noise source according to the standard method, ISO 11904-1. Personal attenuation rating (PAR) of the earmuffs was measured based on the MIRE method using a noise dosimeter (SVANTEK, model SV102). Results: The results showed that means of PAR of the earmuffs are from 49% to 86% of the nominal NR rating. The PAR values of earmuffs when a typical eyewear was worn differed statistically (p < 0.05). It is revealed that a typical safety eyewear can reduce the mean of the PAR value by approximately 2.5 dB. The results also showed that measurements based on the MIRE method resulted in low variability. The variability in NR values between individuals, within individuals, and within earmuffs was not the statistically significant (p > 0.05). Conclusion: This study could provide local individual fit data. Ergonomic aspects of the earmuffs and different levels of users experience and awareness can be considered the main factors affecting individual fitting compared with the laboratory condition for acquiring the labeled NR data. Based on the obtained fit testing results, the field application of MIRE can be employed for complementary studies in real workstations while workers perform their regular work duties.