Search published articles


Showing 18 results for Tayebi


Volume 2, Issue 4 (10-2016)
Abstract

Background: Streptococcus agalactiae, also known as Group B Streptococcus (GBS) is a commensal organism in the urogenital tract and rectum in approximately 25% of the healthy adult female population. The bacterium is the leading cause of bacterial meningitis, pneumonia, and sepsis in human infants.
Materials and Methods: Our study was performed over a three - month period from April to June 2014. Midstream specimens of urine were collected from outpatients suspected of having a bacterial urinary tract infection, which had not received any antibiotics. Group B Streptococci isolates were confirmed by typical colony morphology and identified by differential tests. Antibiotic susceptibility testing was carried out by disk diffusion method on Mueller Hinton agar (Merck, Germany) based on (CLSI) Guidelines 2012.
Results: GBS strains were isolated from 264 (21.1%) cases (out of 1249 positive bacterial urine cultures). The higher prevalence was recorded in the 15-44 and 45-64 age groups. Antibiotic susceptibility tests revealed that vancomycin, penicillin, and linezolid had the lowest, and tetracycline had the highest resistance rate.
Conclusion: In conclusion, the results of the present study confirm the universal susceptibility of GBS strains to the penicillin family and assert the use of penicillin or ampicillin as the first drug of choice for treatment and prophylaxis against GBS infections. However, it is important to perform antibiotic susceptibility testing whenever penicillin could not be prescribed.

Volume 3, Issue 2 (Spring 2021)
Abstract

COVID-19 pandemic, as an unprecedented phenomenon in the modern world, has considerably damaged the international trade, business and supply chain. Previous researches show that although, some restrictions and quarantine are helpful for decreasing the negative impacts of the pandemic, but these have cause trade and economic crisis. In this environment, the World Customs Organization (WCO) plays a pioneering role in combating against the damaging effects of the COVID-19 pandemic. It has invited all its members to share their best practices and policies for preventing the spread of the pandemic. The WCO categorizes them into 4 distinctive groups: facilitating the cross-border movement of relief and essential supplies, supporting the economy and sustaining supply chain continuity, protecting staff and society. This research shows that the mentioned practices and policies can significantly reduce the trade and economic recession of the pandemic and implementation of these practices in critical times can be useful to promote the economy and trade and can help the researchers, policy-makers and stakeholders in combating the negative effects of the pandemic.

Volume 4, Issue 2 (spring 2022 2022)
Abstract

Land use planning, classification of human activity in geographical space, is a thinking that considers all aspects of a country's development, and is a strategic planning and a purely geographical solution for the sustainable development of countries. This issue is more important for Kermanshah province which is neighboring with Iraq, because the existence of a wide range of potential and actual threats in both Iraq and the Kurdistan region have led the implementation of any plan to be corresponded with the analysis of the security situation around the border. Achieving this requires recognizing geostrategic features, analyzing the environment, categorizing the types of threats and identifying their source and origin. This article also serves this purpose, namely presentation of indicators of military centers and bases in Kermanshah province using descriptive-analytic method. The data collection tool is based on documentary and library findings. For this purpose, the required data were collected from documents and written sources and content analysis method is used to analyze the data. The results showed that the arrangement of military centers and bases in Kermanshah province is not very comprehensive and efficient, and it has a traditional approach and has been done regardless of natural and human indicators and threat points, so it has little effect on the effectiveness of projects, decrease in vulnerabilities and increase in defensive capabilities. Also, it is faced with ignoring internal and external threats, unbalanced spatial organization in the manner of establishing and locating military centers, excessive concentration of political, administrative, demographic places and centers, important industries and facilities in the center of Kermanshah province, etc

Volume 6, Issue 3 (Summer 2021)
Abstract

Aim: An Objective measure of ergonomic risk factors in the workplace performs a significant role in preventing the prevalence of Work-related Musculoskeletal Disorders (WMSDs). Hairdressers are exposed to various safety and health risk factors due to the nature of their job. This study aimed to assess the risk of prevalence of WMSDs in female hairdressers.
Method and Materials: In this study, the physical postures of 70 female hairdressers were assessed using Rapid Upper Limb Assessment (RULA) and Novel Ergonomic Postural Assessment (NERPA) and then the Nordic Questionnaire (NQ) was used to assess the prevalence of WMSDs.
Findings: RULA and NERPA final score in the worst and longest postures for hairdressers was 7. The highest prevalence of WMSDs was reported in the shoulder, knee and, neck area of the body. There was a significant relationship between hairdresser’s age and the prevalence of WMSDs in the shoulders, back, waist, knees and, ankles areas. The prevalence of WMSDs was found to have a significant relationship with standing-sitting activities.
Conclusion: The findings of this research revealed that the study population had a high prevalence of WMSDs, especially in the shoulder, knee and, neck areas. This study suggested that the conditions of the workplace should be improved. Therefore, in addition to improving working conditions, it is recommended that hairdressers be trained in identifying workplace hazards and so using proper ergonomic standards while working.


Volume 8, Issue 1 (6-2018)
Abstract

In recent decades, knowledge-based organizations (KBO) have played an important role in growth and economic development, especially in resistance economy by commercializing their scientific and technological achievements. This paper has identified the most important features of successful knowledge-based organizations in Iran. This article is a fundamental research in terms of purpose and utilizes mix method and content analysis based on papers found in the field of Iranian knowledge-based companies. At first features are identified and network analysis is done proportional to it. Then Shannon entropy is used to determine the impact coefficient of these features. The results show that 14 important features of these companies are as follows: qualified human resources, strong management, project and organizational capabilities, good business strategy, optimal management of financial resources, technical and production capabilities, marketing and sales capabilities, good technology strategy, receiving governmental timely incentives, receiving purposive incentives from funding agencies, appropriate networking, proper use of infrastructure, giving enough attention to the organization’s environment and focused activities .

Volume 12, Issue 2 (summer 2012 2012)
Abstract

This paper examines the impact of official development assistance on government fiscal behavior in the Selected Asian developing countries by using Panel Data over the period 1990-2009. The aim of official development assistance is to help developing countries to speed up economic growth and development, income distribution and poverty reduction. But official development assistance is mainly channeled to the domestic economy through the public sector. However, the economic effectiveness of official development assistance has always been a controversial issue. While some researchers argue that such aid results into the growth of bureaucracies, others argue that it can lead to economic growth. The final effects of official development assistance depend on how it influences fiscal policy. Empirical results indicate that official development assistance has a positive and significant effect on capital expenditures and does not have a significant effect on government consumption expenditures and government revenues. Also, official development assistance is a substitute for government borrowing.  
Ali Tayebi, Behzad Ghadiri, Mehrdad Manzari,
Volume 13, Issue 7 (10-2013)
Abstract

Smoothed particle hydrodynamics (SPH) is a fully Lagrangian particle method which solves a problem without using any mesh or grid. Pressure fluctuation is one of the main drawbacks of the weakly compressible SPH (WCSPH) method that leads to an inaccurate pressure distribution. In the present work, a diffusive term is added to the continuity equation to suppress the density and consequently pressure fluctuations. In contrast to the mesh-based methods, flow separation and inflow/outflow boundary conditions are two challenging issues in the SPH method. To overcome these problems, a new algorithm for inflow/outflow boundary condition as well as a particle shifting method is utilized for simulation of flow past a cylinder. Comparing the results with those of literature, it is shown that the method is capable to decrease the pressure fluctuations and solve problems including open boundaries as well as flow separation.
Younes Shekari, Ali Tayebi,
Volume 15, Issue 9 (11-2015)
Abstract

In the present research, the high-order DG-ADER method is used to solve governing equations of two-phase drift flux model. The drift flux model is suitable for studying two-phase flows where the phases are strongly coupled. This model is composed of three differential equations including two continuity equations for two phases and a mixture momentum equation. The mixture model uses also an algebraic relation to link the velocity of the phases. The high-order DG-ADER numerical method, which is a new scheme to get high order accuracy of results, is used to solve the governing equations. The DG-ADER is a nonlinear method in which the reconstruction process is performed using WENO method and the time evolution part is achieved by discontinues Galerkine approach. The results are compared with those reported by other researchers. Three problems including two two-phase shock tubes and a pure rarefaction test problem are solved using this method. The results show that DG-ADER method can solve the two-phase flow problems with a very good accuracy even on a coarse grid. The drawback of this method is presenting numerical fluctuations with limited domain at the position of shock waves.

Volume 16, Issue 1 (Spring 2016 2016)
Abstract

The lack of resources and the communities' demands for various goods and services require effective prioritization of investment in different sectors of the economy. Prioritization could optimize resources allocation in addition to improve the social welfare level. This paper provides a framework for prioritizing investment in the services sector according to the aims and policies of A.T. organization. To do this, following determination of factors affecting investment priorities, this paper uses Fuzzy TOPSIS method as a model for setting priorities, since traditional methods in setting priority are insufficient in confronting with vague situations and linguistic evaluations. This method is based on combination of experts and decision-makers’ views in the form of qualitative performance evaluation indicators, which are expressed as triangular fuzzy numbers. The findings indicate that investment in financial and insurance services takes top priority over other services.
Hassan Zamanipour, Pourya Omidvar, Ali Tayebi,
Volume 17, Issue 2 (3-2017)
Abstract

In this paper, the convection-diffusion process in a two-phase air-water flow is investigated. Two-phase flows of air and water are important and are widely used in the industrial applications. Simulation of such a flow needs a proper understanding of the interface between two phases where these is a change in fluids properties. Smoothed Particle Hydrodynamics (SPH) is a fully Lagrangian and meshless method which can simply detect the interface of multiphase flows. Here, we develop the open-source SPHyiscs2D code into two phase and implement the convection-diffusion equation by looking carefully at surface tension forces. To validate, first the still-water problem is investigated to ensure that the hydrostatic pressure at the interface is predicted and then the dam-break problem on an infinite bed is compared with the available experimental data. Results show that the combination of surface tension formulations and an additional artificial force gives a better result. Finally, the convection-diffusion process and the concentration distribution are shown for the air-bubble rising problem for different diffusive coefficients. It will be shown that the SPH method is a useful tool for studying multiphase flows and convection-diffusion processes.
Payam Tayebi, Ali Fazli, Parviz Asadi, Mahdi Soltanpour,
Volume 18, Issue 3 (5-2018)
Abstract

In this paper, the single point incremental forming (SPIF) of friction stir welded (FSWed) 5083 aluminum alloy sheets are investigated experimentally and numerically. The aluminum sheets with 2mm thickness are friction stir welded with the same FSW parameters. In order to obtain the effect of FSW on the formability of SPIF, the base sheets and FSWed sheets are formed to conical shapes with different forming angles and then the limiting wall angles are determined for each condition. The experimental results indicate that the limiting forming angle of FSWed sheet is not so much different than the base sheet and FSW does not have a negative effect on the sheet metal formability in SPIF. To study the effect of SPIF and FSW in mechanical and microstructural properties of the formed parts, the effects of these process on the grain size and micro-hardness is investigated. Furthermore, the incremental forming is numerically simulated using the ABAQUS software and the sheet thickness distribution, obtained from the simulation, is compared with the experimental results. After verification of the numerical simulation model, the effect of FSW on the thickness distribution and strain distribution in SPIF is studied. The results indicate that in weld region and base metal region, the distributions of thickness and major strain are uniform while the distribution of minor strain is non-uniform.

Volume 18, Issue 114 (August 2021)
Abstract

Optimization of extraction of bioactive compounds from seedless barberry fruit using pulsed electric field pretreatment
Abstract
 
In this research, in order to optimize the extraction process of Ethanolic extract of barberry fruit, the increase and optimization of the conditions for the extraction of anthocyanin's and bioactive compounds by means of intermittent electric field pre-treatment from three levels of electric field intensity (0.5, 1.75 and 3 kV / cm) and 3 levels of number of pulses (15, 30 and 45); then with ethanol solvent was used to extract their extracts and the amount of flavonoids, total anthocyanin, DPPH, total phenolic compounds, iron regeneration capacity, vitamin C and acidity compared to control (no treatment)  Was studied. The results showed that the total phenol content of the extract decreased by increasing the number of pulses and reducing the intensity of the pulsed electric field applied to the sample. The increase in the electric field strength and the number of pulses initially increased the flavonoid content, DPPH and iron ion recovery capacity, but with the increase of these variables, these three parameters decreased. Also, with increasing of these parameters, the anthocyanin level and vitamin C content increased. The acidity of the sample was reduced and then increased by increasing the electric field strength and applied pulse number. Regarding the results of the process optimization, it can be concluded that the electrical field intensity of 2.003 kV / cm and applying 29 pulses can increases the antioxidant properties of the produced product compared with the control sample.

 

Volume 19, Issue 2 (7-2019)
Abstract

Investigation of multi-physics problems such as flow-structure interaction (FSI) in free surface is very important in mechanical engineering, whereas numerical simulations of such problems have been widely conducted by researchers. The implementations of CFD in engineering applications are most of the time based on the Eulerian description. In this method, one can focus on flows at a fixed spatial point x at time t and any flow variable Φ is expressed as Φ (x, t). This description has been studied for over fifty years and is clearly understood. Most of commercial codes have been developed by using finite difference, finite element and finite volume approaches. Simulating free surface flow with most Eulerian CFD methods is potentially very difficult as explicit treatment of the free surface is required. Moreover, The problems of most Eulerian and mesh-based numerical methods for complex free surface deformations involves difficulties and complexities of various boundaries remeshing as well as moving boundaries and exact determination of free- surface fluid. Another description of study of CFD is the Lagrangian method where one can follow the history of an individual fluid parameter through the time. In the Lagrangian methods, any flow variable is expressed as Φ (x0, t), where the point vector x0 of the particle at the reference time t = 0. Smoothed Particle Hydrodynamics (SPH) is a meshless and fully Lagrangian method which is able to simulate the FSI problems due to its simplicity and capability, as there is no special treatment needed for the free surface. The current problem in hydrodynamic science and fluid engineering is studied as a complex phenomenon in free-surface flow. Smoothed Particle Hydrodynamics (SPH) is a flexible Lagrangian and meshless technique for CFD simulations initially developed by Lucy (1977) and Gingold and Monaghan (1977) to simulate the nonaxisymmetric phenomena in astrophysics. In recent years, the SPH method has been very popular in fluid mechanics, e.g. multiphase flows,3 heat conduction,4 underwater explosions, free-surface flows, etc. In this method, each particle carries an individual mass, position, velocity, internal energy and any other physical quantity. The Lagrangian nature of SPH would lead this method to be well suited to problems with large deformations and distorted free surfaces. Simplicity, robustness and relative accuracy in comparison with other numerical methods are the main advantages of using SPH.10 Moreover, the SPH method can handle fully nonlinear, multiply-connected free-surface problems and extend computations beyond wave breaking, which need complex treatments in other grid-based methods, e.g. Volume of Fluid (VoF).In this approach the computational domain is formed by a set of particles. Each particle represents macroscopic volume of fluid conveying information about the mass, density, pressure, speed, position and the other parameters related to the nature of the flow. However, the computational cost is a disadvantage of SPH because the time step is small because of the explicit integration scheme in a weakly compressible formulation. This method has been successfully applied to a range of free-surface problems which involve breaking and splashing up There is a choice of SPH formulation in the literature mostly expressed in weakly compressible forms where pressure is obtained from the equation of state In this research, SPH is used to investigate the flow-structure interaction in free surface. First, the simulation of dam break problem on a dry and infinite bed is shown and compared with the experimental data. Then, and after implementing the governing equations, the vibration of a beam is studied. Finally, the dam break problem on an elastic gate is shown. Comparison between the SPH results and available numerical and experimental data shows that the SPH method is useful method for simulating the FSI problem.

Volume 20, Issue 3 (10-2020)
Abstract

The history of the human efforts for safety against earthquakes shows the catastrophic and harmful events, even nowadays. The majority of decisions in seismic safety policy are based on randomness assumption for earthquake time series. The accuracy of this assumption assessment, can accurate the strategies and resulted in more secure decisions. Also in structural control context, seismic time series prediction in the feedback systems, can reduces the time of control system reaction and in subsequent decreases structural damages. Recent studies have shown that dynamical structure of these complex time series can be better understand using nonlinear dynamics theory. In the present paper, we evaluate randomness and nonlinear characteristics of 9 earthquakes time series from metropolitan Tehran earthquake database using chaos theory conceptions. These earthquakes are Arjomand, Bumahen, Damavand, Eshtehard, Firuzkooh, Taleqan 1, Taleqan 2, Taleqan 3 and Tehran earthquake. To this end, we reconstruct phase space for delay time calculation using average mutual information function. Embedding dimension is calculated based on false nearest neighbors. Correlation dimension is used for earthquake chaotic behavior assessment and local prediction algorithm and artificial neural network are employed for earthquake prediction. Results illustrate nonrandom nature of evaluated earthquakes. These earthquakes have high dimension chaotic behavior. Earthquake prediction is good and acceptable accuracy using chaos theory and artificial neural network. The existence of the specific attractors in a part of 2D reconstructed phase space for the earthquakes show the presence of a nonlinear processes. This is an evidence for no stochastic behavior of the earthquakes. Also, reduction in the false neighbors with embedding dimension increases, shows no stochastic time series. Lyapanov exponent positive gradient displays a nondeterministic process, although it cannot warranty the chaotic behavior. Correlation exponents have high values for Taleqan1 and Tehran earthquakes. So these earthquakes saturate in large quantities. Bumahen and Damavand earthquakes correlation exponents have increasing trend and do not saturate. These observations prove the chaotic behavior of high dimension or random process with inconsiderable chaos. So these earthquakes cannot be predicted properly. Performing the local prediction based on the selected embedding dimensions and the neighbor’s number, showed that the predicted time series are relatively good for the earthquakes of Arjomand, Eshtehard, Firuzkooh, Taleqan 2 and Taleqan 3. Proper anticipated of trends, upward and downward branches as well as amplitudes illustrate the chaotic nature of the earthquakes. The correlation coefficient for Arjomand, Eshtehard, Firuzkooh, Taleqan 2 and Taleqan 3 are 0.9541, 0.4494, 0.5124, 0.6600 and 0.3697 respectively. In the case of Talegan1 and Tehran earthquakes, time series amplitudes and peaks do not predicted appropriately, but the prediction is acceptable. Correlation coefficient of Taleqan1 and Tehran are 0.2452 and 0.1760 respectively. Bumahen and Damavand earthquakes do not trace properly. It should be noted that for each earthquake, 20% of the endpoints of accelerations are used to evaluate the prediction process. According to the results of the analysis and earthquakes prediction in Tehran region, using phase reconstruction and artificial neural networks, we can say that the dynamics governing the earthquakes in this region are not random, but, chaos with high dimension. Earthquake prediction is good and acceptable accuracy using chaos theory and artificial neural network.

Volume 20, Issue 4 (winter 2020 2020)
Abstract

Due to the fundamental differences in technology, factor abundance, labor productivity and economic capacities, developing countries need to attract FDI in order to achieve sustainable development goals. FDI transfers a variety of spillover effects including advanced technology, modern management and productive capital which properly help saving and promoting the environment. Indeed, FDI develops economic potentials of developing countries to expand export markets and to participate in the global economy, a fact that quantitative values lead to qualitative ones. Now, the question arises whether attracting any kind of FDI by emerging and developing economies leads to high-value employment opportunities, or preserves the environment. Do sustainable FDI flows secure sustainable development goals in developing countries? The basic hypothesis of this study is based on assessing the validity of this claim, subject to being empirically tested. This study investigates the effect of FDI on the sustainable development process in selected developing economies by using a panel data model over the period 2000-2018. The results indicate the significant effect of FDI and its spillover on sustainable development of selected countries. However, environmental pollution has statistically a negative and significant effect on sustainable development in these countries. The negative interaction effect of FDI and carbon dioxide emission on sustainable development indicates that if FDI triggers environmental pollution in host countries, it will hinders the path to sustainable development.

Reza Adabi, Mani Fathali, Gholamhosein Pouryoussefi, Alireza Doostmahmoudi, Mostafa Amiri Tayebi,
Volume 22, Issue 3 (March 2022)
Abstract

 In this research, the turbulent isotropic flow has been experimentally investigated. Hence, two different grids are made and a contraction channel is installed behind it inside the subsonic wind tunnel to generate an isotropic turbulence flow.  The grids with mesh sizes of 2/54 cm and 5/08 cm were cut on the wood with obstruction ratio of 0/34 and 0/17, respectively. One-dimensional hot wire was used to determine the perturbation velocities in the direction of flow, and an approximation was used to determine the components of other directions. At speeds of 5 m/s and 10 m/s, experiments were performed for each of the grids, which range from a Reynolds number of 8500 to about 33000. To determine the onset of the isotropic location, methods of velocity skewness, kurtosis, turbulence intensity, dissipation rate, and longitudinal scales such as Kolmogorov and Taylor lengths were used. For skewness and kurtosis, the numbers show 0 and 3, respectively, which indicate the isotropic flow. Results showed that with increasing the velocity, the isotropy of the flow was delayed. Also, in a grid with a lower obstruction ratio, the intensity of turbulence will be less near the grid, but as it moves away from the grid, the intensity of turbulence will increase.

Volume 23, Issue 3 (10-2019)
Abstract

The purpose of this research is to study the co-authorship among researchers in field of strategic management in Iran. The method of this research is descriptive-analytical and has been done by scientometric approach. The statistical population of research consists of all articles and authors of internal articles in field of strategic management and collectively contain 320 articles in 32 internal journals related to this field that have been identified during the period from 2001 to 2016. Social network analysis was used for analyzing data and also UCINET and Gephi software has been used in order to analyze co-authorship network. The findings show that the most used authoring pattern to produce these articles is two-authorship. 606 unique authors have contributed to form the network of articles, that 102 authors among them have played an influential role. This research showed that Azar, Khodadad Hosseini, and also jointly Hosseini and Seyedjavadin have earned first to third ranks in terms of frequency of articles. Azar, Khodadad Hosseini and Hosseini respectively were ranked first to third in rank centrality.

Volume 26, Issue 2 (Spring 2023)
Abstract

The escalating incidence of foodborne diseases caused by pathogenic bacteria presents a substantial global health concern. Microbial spoilage of food not only shortens product shelf life but also increases the risk of foodborne diseases. According to the World Health Organization, one in ten people worldwide falls ill after consuming contaminated food. While foodborne diseases are preventable, the implementation of effective strategies to control and prevent these illnesses remains a critical global challenge. The unique properties of both organic and inorganic nanoparticles have attracted significant attention in the food industry due to their potential to enhance nutritional, safety, and quality attributes of food products. A majority of foodborne infections are attributed to pathogens such as Salmonella, Listeria, Escherichia coli, Clostridium, and Campylobacter. Silver and silver-based compounds have been shown to exhibit potent antimicrobial activity against a broad spectrum of bacteria. The current body of knowledge regarding the application of silver nanoparticles for the elimination of foodborne pathogens is expanding rapidly, providing opportunities to explore their mechanisms of action, benefits, and limitations. This perspective aims to identify novel strategies for reducing the burden of foodborne diseases by critically evaluating the potential of silver nanoparticles. Furthermore, the potential health implications of silver nanoparticles for human consumption will be discussed to inform the development of effective policies for public health.
 

Page 1 from 1