A novel numerical modeling of microsecond laser beam percussion micro-drilling of Hastelloy X:experimental validation and multi-objective optimization

The paper investigates the characteristics of the laser beam percussion micro-drilling (LBPMD) process in aerospace nickel-based superalloy Hastelloy X using microsecond pulses. The quality of the drilled hole is crucial in laser beam micromachining, and selecting appropriate process parameters significantly impacts the hole’s quality. The objective is to achieve predefined hole dimensions with minimal taper angles. Additionally, the study focuses on the alteration of pulse width, which is a combination of laser pulse frequency and duty cycle. Laser power (P), duty cycle % (D), focal plane position (FPP), and laser frequency (f) are considered input parameters, while geometric features such as inlet and outlet diameters, hole taper angle, and inlet circularity are examined as process responses. ANOVA is employed to establish significant relationships between process parameters and response variations based on experimental tests. Creating a precise simulation model that accurately accounts for the moving boundary of the target material’s receding surface is a crucial and challenging task in formulating the laser heat conduction problem. It is necessary to simultaneously capture the material’s dynamic front movement and update the boundary conditions of the laser source. To model the micro-drilled hole with LBPMD, the UMESHMOTION and DFLUX subroutines, along with the arbitrary Lagrangian-Eulerian (ALE) adaptive remesh algorithm in the Abaqus™ software, are utilized. Notably, no previous numerical study has predicted the geometry of micro-drilled holes using this technique. The proposed procedure is validated through the predictions of inlet and outlet hole diameters. Special emphasis is placed on the validation of models. Consequently, the numerical model and statistical model are compared as well as the need to define model applicability. The study demonstrates that all input parameters significantly influence the inlet hole diameter, while the pulse width notably affects the taper angle and circularity. The interaction between high laser frequency and low duty cycle results in reduced pulse duration. Multi-objective optimization is performed to determine the optimal process parameter settings for desired quality characteristics, considering minimum hole taper angle, precise inlet diameter, and maximum inlet circularity of the hole as optimization criteria. The findings show that with the optimized predicted results obtained from the optimal input variables, a composite desirability of 92% can be achieved

Comparative Investigation of Health Quality of Air in Tehran, Isfahan and Shiraz Metropolises in 2011-2012

Background and Aims: Air pollution causes wide spectrum acute and chronic effects of health from slight physiological disorders to death from cardiovascular and respiratory diseases. In order to set the control programs, air pollution monitoring and determination of air quality are necessary. The objective of this study was to compare health quality of air in Tehran, Isfahan and Shiraz cities in 2011- 2012.Materials and Methods: This Study was a descriptive–analytic study. The moment concentrations of Tehran,Isfahan and Shiraz air pollutants were gathered through referring to the environmental protection agency.Then, Air Quality Index (AQI) was calculated based on the criteria pollutants’ levels (CO, NO2, SO2, PM10,PM2.5 and O3) for three cities through linear interpolation and was classified into describing classes accordingto tables of National Ambient Air Quality Standards. Data analysis was performed with Excel and SPSS software using One-Way ANOVA test.Results: The results showed that the AQI in Tehran, Isfahan and Shiraz was higher than Iran’s environmental protection agency standards (AQI>100) in 341, 323 and 85 days, respectively. Furthermore, particulate matter (PM10) has been the critical pollutant in three cities for most days of the year. One-Way ANOVA test between AQI mean of the three cities showed a significant difference.Conclusion: The air quality of the three cities was unhealthy in 2011-2012 and the situation of Tehran andIsfahan air, however, was in the “bad situation”.Key words: Air pollutants, Air quality index, Pollution standard index, Responsible pollutan

El impacto de las fluctuaciones del precio del petróleo en el poder de préstamo bancario en Irán: una aplicación del enfoque GMM

The abundance of oil resources and the dependence of the state budget on crude oil exports have exposed Iran's single-product economy to oil price fluctuations and its consequences. On the other hand, according to the country's financial system and its being bank-centric, one of the sectors that are constantly affected by oil price fluctuations is the banking system and its performance. To this end, the present study investigated the impact of oil price fluctuations on lending power of specialized banks in Iran using seasonal data from 1999 to 2018 using by Generalized Method of Moments (GMM). The results of this study indicate that during the period under review, oil price fluctuations has been a negative and significant effect (coefficient of -0.01) on the credit growth of specialized banks. In addition, GDP growth and inflation have been, respectively, a positive and negative effect (coefficients of 0.09 and -0.09) on the lending power of specialized banks during the period under review.La abundancia de recursos petroleros y la dependencia del presupuesto estatal de las exportaciones de petróleo crudo han expuesto la economía de un solo producto de Irán a las fluctuaciones del precio del petróleo y sus consecuencias. Por otro lado, de acuerdo con el sistema financiero del país y su bancarización, uno de los sectores que se ve constantemente afectado por las fluctuaciones del precio del petróleo es el sistema bancario y su desempeño. Con este fin, el presente estudio investigó el impacto de las fluctuaciones del precio del petróleo en el poder de préstamo de los bancos especializados en Irán utilizando datos estacionales de 1999 a 2018 utilizando el Método Generalizado de Momentos (GMM). Los resultados de este estudio indican que durante el período bajo revisión, las fluctuaciones del precio del petróleo han tenido un efecto negativo y significativo (coeficiente de -0.01) en el crecimiento del crédito de los bancos especializados. Asimismo, el crecimiento del PIB y la inflación han tenido, respectivamente, un efecto positivo y negativo (coeficientes de 0,09 y -0,09) sobre el poder crediticio de los bancos especializados durante el período analizado

Evaluation of cardiovascular and respiratory mortality attributed to atmospheric SO2 and CO using AirQ model

Background: Air pollutants have multiple adverse effects on human health. In this study, the health effects of exposure to carbon monoxide (CO) and SO2 in the air of 6 Iranian metropolises in 2011-2012 were examined. Methods: Raw data was collected from the Iranian Department of Environment and the Iran Meteorological Organization. After validation, the required statistical indices were calculated through programming and modifying temperature and pressure in Excel software. The output of Excel was given to the AirQ model, and the results were presented as the cases of death. Results: The annual mean concentrations of SO2 were 2.45, 1.55, 0.6, 0.55, 1.05, and 3.8 times higher than the guidelines of the World Health Organization (WHO) (20 μg/m3) in Tehran, Mashhad, Isfahan, Shiraz, Tabriz, and Urmia, respectively. The concentrations of CO did not exceed the standard limit in any of the studied cities. The cumulative numbers of total deaths attributed to SO2 were 744, 122, 132, 44, 37, and 107 in Tehran, Mashhad, Isfahan, Shiraz, Tabriz, and Urmia, respectively. The highest mortality rate was found in Urmia at 2.9% followed by Tehran at 1.52%; the lowest rate of 0.46% was found in Tabriz. Conclusion: The results show that of the 6 metropolises, the highest CO mortality rate of about 2.15% belonged to Isfahan followed by Arak with about 1.38%, and the lowest rate of 0.68% belonged to Mashhad. Because of the growing trend of air pollution and its mortality rate and adverse effects, practical solutions for the control and reduction of air pollution in Iranian metropolises are necessary

The effect of board characteristics on modified audit opinion

The board of directors, represented by the company's shareholders, supervises and controls the company. In the governance of the company, which is efficient and responsible for all those who communicate with the stakeholders, it is the director who is responsible for coordination and ensures the existence of culture and proper atmosphere in the system. The purpose of this research is to study the effect of the characteristics of the board of directors on the modified audit opinion of the company. The output of this research is limited to the years 2013-2020, and this research has one main hypothesis and four sub-hypotheses. The purpose of the research is applied research, and the research method is correlational in nature. The research was done in inductive analogical reasoning and panel elimination was used to analyze the hypotheses. The results of the research hypothesis test showed that the size of the board of directors has a positive and significant effect on the modified audit opinion of the company. Board independence has a negative and significant impact on the modified audit opinion. However, the impact of tenure and gender diversity on the modified audit opinion is not significant

بررسي مقايسه اي كيفيت بهداشتي هواي كلانشهرهاي تهران، اصفهان و شيراز در سال 1390

Background and Aims: Air pollution causes wide spectrum acute and chronic effects of health from slight physiological disorders to death from cardiovascular and respiratory diseases. In order to set the control programs, air pollution monitoring and determination of air quality are necessary. The objective of this study was to compare health quality of air in Tehran, Isfahan and Shiraz cities in 2011- 2012.Materials and Methods: This Study was a descriptive–analytic study. The moment concentrations of Tehran,Isfahan and Shiraz air pollutants were gathered through referring to the environmental protection agency.Then, Air Quality Index (AQI) was calculated based on the criteria pollutants’ levels (CO, NO2, SO2, PM10,PM2.5 and O3) for three cities through linear interpolation and was classified into describing classes accordingto tables of National Ambient Air Quality Standards. Data analysis was performed with Excel and SPSS software using One-Way ANOVA test.Results: The results showed that the AQI in Tehran, Isfahan and Shiraz was higher than Iran’s environmental protection agency standards (AQI>100) in 341, 323 and 85 days, respectively. Furthermore, particulate matter (PM10) has been the critical pollutant in three cities for most days of the year. One-Way ANOVA test between AQI mean of the three cities showed a significant difference.Conclusion: The air quality of the three cities was unhealthy in 2011-2012 and the situation of Tehran andIsfahan air, however, was in the “bad situation”.زمينه و هدف: امروزه وضعيت نامطلوب كيفيت هوا در كلانشهرها موجب ايجاد طيف وسيعي از اثرات بهداشتي حاد و مزمن ازاختلالات جزئي فيزيولوژيكي گرفته تا مرگ ناشي از بيماري هاي تنفسي و قلبي عروقي مي شود. بنابراين پايش آلاينده ها و تعيين مستمركيفيت هواي كلانشهرها به منظور تدوين برنامه هاي كنترل آن، ضروري است. لذا هدف اين مطالعه، مقايسه كيفيت بهداشتى هوايشهرهاي تهران، اصفهان و شيراز در سال 1390 مى باشد.مواد و رو شها: اين مطالعه از نوع توصيفي- تحليلى م ىباشد. غلظ تهاي لحظه اي آلايند ههاي هواي شهرهاي تهران، اصفهان و شيراز بامراجعه به سازمان حفاظت محيط زيست بدست آمد. سپس شاخص كيفيت هوا از طريق درون يابى بين غلظت آلاينده ها براي آلاينده های معیار هوای سه شهر و برمبنای جدول استاندارد کیفیت بهداشتی هوا به طبقات توصیف کننده طبقه بندی گردید. نتيجه گيري: كيفيت هواي سه شهر درسال 1390 بهداشتى نبوده و هواي شهرهاي تهران و اصفهان وضعيت نامطلوبترى نسبت به هوايشيراز داشته است

Report an educational intense decline in medical student with excellent educational background

Educational decline among university students during the first university terms is generally observed as a reason of the big change in lifestyle and not being accustomed to dormitory atmosphere, or it can be as a result of being involved with emotional matters, due to the special age at which they enter university. This research concerns the situation of a medical student ((Mohammad)) who enters Kerman medical university with a perfect educational background and a top rank in entrance exam of university but he encounters a noticeable underachievement in educating as soon as he starts his courses at university. Mohammad who is from a relatively supportive family and has a suitable financial situation in his family, gets involved with an emotional case and its following problems and matters, facing a breakup at this stage , he is suffered with depression and severe educational decline . His family, in order to help him, acts mistakenly and it brings about bigger problems. Therefore, after finishing two university terms with conditional educational situation, he exposes with the warning of being dropped out of university. Noticing the importance of this stage of life among university students, more than the consideration of university teachers, needs the contribution of consulting center of university in an effective way. so that they can identify students with emotional conflicts that leads them toward educational underachievement, and then offering them suitable and helpful consultation aimed to help them pass this serious phase of life and moreover, how to adopt themselves with new situations, surely with having their family support as well. Key Words: Educational Decline, Medical Student, Consultatio

Estimation of Short-term Mortality and Morbidity Attributed to Fine Particulate Matter in the Ambient Air of Eight Iranian Cities

Amongst the various pollutants in the air, particulate matters (PM) have significant adverse effects on human health. The current research is based on existing epidemiological literature for quantitative estimation of the current health impacts related to particulate matters in some selected principal Iranian megacities. In order to find the influence of air pollution on human health, we used the AirQ software tool presented by the World Health Organization (WHO) European Centre for Environment and Health (ECEH), Bilthoven Division. The adverse health outcomes used in the study consist of mortality (all causes excluding accidental causes), due to cardiovascular (CVD) and respiratory (RES) diseases, and morbidity (hospital admissions for CVD and RES causes). For this purpose, hourly PM10 data were taken from the monitoring stations in eight study cities during 2011 and 2012. Results showed annual average concentrations of PM10 and PM2.5 in all megacities exceeded national and international air quality standards and even reached levels nearly ten times higher than WHO guidelines in some cities. Considering the short-term effects, PM2.5 had the maximum effects on the health of the 19,048,000 residents of the eight Iranian cities, causing total mortality of 5,670 out of 87,907 during a one-year time-period. Hence, reducing concentrations and controlling air pollution, particularly the presence of particles, is urgent in these metropolises

Association between the rs2241883 polymorphism of the fatty acid-binding protein-1 (FABP1) gene and obesity in a population of MASHAD study cohort

Funding Information: We would like to thank Mashhad University of Medical Sciences Research Council for their financial supports.Peer reviewedPublisher PD

Bushehr Elderly Health (BEH) Programme, phase I (cardiovascular system)

Purpose: The main objective of the Bushehr Elderly Health Programme, in its first phase, is to investigate the prevalence of cardiovascular risk factors and their association with major adverse cardiovascular events. Participants: Between March 2013 and October 2014, a total of 3000 men and women aged ≥60 years, residing in Bushehr, Iran, participated in this prospective cohort study ( participation rate=90.2%). Findings to date: Baseline data on risk factors, including demographic and socioeconomic status, smoking and medical history, were collected through a modified WHO MONICA questionnaire. Vital signs and anthropometric measures, including systolic and diastolic blood pressure, weight, height, and waist and hip circumference, were also measured. 12-lead electrocardiography and echocardiography were conducted on all participants, and total of 10 cc venous blood was taken, and sera was separated and stored at –80°C for possible future use. Preliminary data analyses showed a noticeably higher prevalence of risk factors among older women compared to that in men. Future plans: Risk factor assessments will be repeated every 5 years, and the participantswill be followed during the study to measure the occurrence of major adverse cardiac events. Moreover, the second phase, which includes investigation of bone health and cognition in the elderly, was started in September 2015. Data are available at the Persian Gulf Biomedical Research Institute, Bushehr University of Medical Sciences, Bushehr, Iran, for any collaboratio