A developed hybrid method for crack identification of beams

Ali. R. Vosoughi 국제구조공학회 2015 Smart Structures and Systems, An International Jou Vol.16 No.3

A developed hybrid method for crack identification of beams is presented. Based on the Euler-Bernouli beam theory and concepts of fracture mechanics, governing equation of the cracked beams is reformulated. Finite element (FE) method as a powerful numerical tool is used to discritize the equation in space domain. After transferring the equations from time domain to frequency domain, frequencies and mode shapes of the beam are obtained. Efficiency of the governed equation for free vibration analysis of the beams is shown by comparing the results with those available in literature and via ANSYS software. The used equation yields to move the influence of cracks from the stiffness matrix to the mass matrix. For crack identification measured data are produced by applying random error to the calculated frequencies and mode shapes. An objective function is prepared as root mean square error between measured and calculated data. To minimize the function, hybrid genetic algorithms (GAs) and particle swarm optimization (PSO) technique is introduced. Efficiency, Robustness, applicability and usefulness of the mixed optimization numerical tool in conjunction with the finite element method for identification of cracks locations and depths are shown via solving different examples.

A hybrid inverse method for small scale parameter estimation of FG nanobeams

Ali. R. Vosoughi,A. Darabi 국제구조공학회 2016 Steel and Composite Structures, An International J Vol.20 No.5

As a first attempt, an inverse hybrid numerical method for small scale parameter estimation of functionally graded (FG) nanobeams using measured frequencies is presented. The governing equations are obtained with the Eringen's nonlocal elasticity assumptions and the first-order shear deformation theory (FSDT). The equations are discretized by using the differential quadrature method (DQM). The discretized equations are transferred from temporal domain to frequency domain and frequencies of the nanobeam are obtained. By applying random error to these frequencies, measured frequencies are generated. The measured frequencies are considered as input data and inversely, the small scale parameter of the beam is obtained by minimizing a defined functional. The functional is defined as root mean square error between the measured frequencies and calculated frequencies by the DQM. Then, the conjugate gradient (CG) optimization method is employed to minimize the functional and the small scale parameter is obtained. Efficiency, convergence and accuracy of the presented hybrid method for small scale parameter estimation of the beams for different applied random error, boundary conditions, length-to-thickness ratio and volume fraction coefficients are demonstrated.

A hybrid DQ-TLBO technique for maximizing first frequency of laminated composite skew plates

Ali. R. Vosoughi,Parviz Malekzadeh,Umut Topal,Tayfun Dede 국제구조공학회 2018 Steel and Composite Structures, An International J Vol.28 No.4

The differential quadrature (DQ) and teaching-learning based optimization (TLBO) methods are coupled to introduce a hybrid numerical method for maximizing fundamental natural frequency of laminated composite skew plates. The fiber(s) orientations are selected as design variable(s). The first-order shear deformation theory (FSDT) is used to obtain the governing equations of the plate. The equations of motion and the related boundary conditions are discretized in space domain by employing the DQ method. The discretized equations are transferred from the time domain into the frequency domain to obtain the fundamental natural frequency. Then, the DQ solution is coupled with the TLBO method to find the maximum frequency of the plate and its related optimum stacking sequences of the laminate. Convergence and applicability of the proposed method are shown and the optimum fundamental frequency parameter of the plates with different skew angle, boundary conditions, number of layers and aspect ratio are obtained. The obtained results can be used as a benchmark for further studies.

Effect of Co-Driver on Job Content and Depression of Truck Drivers

Hatami, Ali,Vosoughi, Shahram,Hosseini, Agha F.,Ebrahimi, Hossein Occupational Safety and Health Research Institute 2019 Safety and health at work Vol.10 No.1

Background: Since the presence of a co-driver can be considered as a companion, partner, or friend for a driver through eliminating driver's loneliness, it plays a significant role in health and safety of drivers. The objective of this study was to investigate the effect of co-drivers on depression and occupational stress on male truck drivers. Methods: This study was an interventional case-control study. Seventy truck drivers were selected and divided into two groups: case (33 truck drivers with co-drivers) and control (37 truck drivers without codrivers). Two Goldberg depression inventories (for evaluating driver's depression) and the Karasek job content questionnaire (for evaluating driver's job stress) were used to collect data which were completed by interview. Results: The results showed that job content values for the case group were higher in all dimensions except job nature. The comparison of the percentages showed significant difference between two groups. Depression rate in drivers with co-driver is truly less than depression rate in drivers without co-driver. There was significant positive relationship between dimensions of job content and depression rate. Conclusion: According to the results of this study, it can be claimed that a co-driver decreases stress and loneliness of drivers, as well as increases work performance and job satisfaction, and, in turn, leads to a decrease in job-related depression.

New Approach for Activation of N2-Selective ETS-4 Membrane for Nitrogen Separation from N2/CH4 Mixture

Zakeri Fatemeh,Vosoughi Mahsa,Maghsoudi Hafez,Denayer Joeri F. M. 한국화학공학회 2024 Korean Journal of Chemical Engineering Vol.41 No.4

Microporous titanosilicate ETS-4 zeotype membrane, with its 4 Å pore openings, is an adequate material for the kinetic separation of nitrogen from methane. Obtaining high N 2 /CH 4 permselectivity, small-sized ETS-4 powder was synthesized by aging method, and then utilized as membrane seeding powder. Highly N 2 -selective ETS-4 membranes were fabricated utilizing a new recipe and the secondary growth approach on α-alumina supports. XRD, FESEM, and EDX studies were used to analyze the synthesized ETS-4 powder and membranes. The eff ect of membrane activation temperature (80–140 °C) on permeance of N 2 was evaluated. In addition to N 2 and CH 4 , the membrane permeance was also evaluated for O 2 and Ar gases. Regarding the ETS-4 membranes, N 2 permeance increased gradually as the activation temperature was raised in the 80–140 °C range, reaching its highest value (i.e., 2.6 × 10 −8 mol m −2 s −1 Pa −1 ) after activation at 140 °C. The permeances of N 2 and CH 4 gases were measured at 30, 50, and 70 °C, and a pressure diff erence up to 600 kPa. N 2 /CH 4 permselectivity of 75.19 (N 2 permeance of 1.94 × 10 –8 mol m- 2 s −1 Pa −1 ) were obtained at 30 °C and 200 kPa of feed pressure. The results revealed that ETS-4 membranes have great potential for N 2 removal from natural gas due to highest N 2 /CH 4 permselectivity among the other membranes.

A new approach for calculation of the neutron noise of power reactor based on Telegrapher's theory: Theoretical and comparison study between Telegrapher's and diffusion noise

Bahrami, Mona,Vosoughi, Naser Korean Nuclear Society 2020 Nuclear Engineering and Technology Vol.52 No.4

The telegrapher's theory was used to develop a new formulation for the neutron noise equation. Telegrapher's equation is supposed to demonstrate a more realistic approximation for neutron transport phenomena, especially in comparison to the diffusion theory. The physics behind such equation implies that the signal propagation speed is finite, instead of the infinite as in the case of ordinary diffusion. This paper presents the theory and results of the development of a new method for calculation of the neutron noise using the telegrapher's equation as its basis. In order to investigate the differences and strengths of the new method against the diffusion based neutron noise, a comparison was done between the behaviors of two methods. The neutron noise based on SN transport considered as a precision measuring point. The Green's function technique was used to calculate the neutron noise based on telegrapher's and diffusion methods as well as the transport. The amplitude and phase of Green's function associated with the properties of the medium and frequency of the noise source were obtained and their behavior was compared to the results of the transport. It was observed, the differences in some cases might be considerable. The effective speed of propagation for the noise perturbations were evaluated accordingly, resulting in considerable deviations in some cases.

A Cascaded Modular Multilevel Inverter Topology Using Novel Series Basic Units with a Reduced Number of Power Electronic Elements

Barzegarkhoo, Reza,Vosoughi, Naser,Zamiri, Elyas,Kojabadi, Hossein Madadi,Chang, Liuchen The Korean Institute of Power Electronics 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.6

In this study, a new type of cascaded modular multilevel inverters (CMMLIs) is presented which is able to produce a considerable number of output voltage levels with a reasonable number of components. Accordingly, each series stage of the proposed CMMLI is comprised of two same basic units that are connected with each other through two unidirectional power switches without aiming any of the full H-bridge cells. In addition, since the potentiality for generating a higher number of output voltage levels in CMMLIs hinges on the magnitude of the dc voltage sources used in each series unit, in the rest of this paper, four different algorithms for determining an appropriate value for the dc sources' magnitude are also presented. In the following, a comprehensive topological analysis between some CMMLI structures reported in the literature and proposed structure along with several simulation and experimental results will be also given to validate the lucrative benefits and viability of the proposed topology.

Landfill Site Selection using GIS and AHP: a Case Study: Behbahan, Iran

Zeinab Ghaed Rahmat,Mehdi Vosoughi Niri,Nadali Alavi,Gholamreza Goudarzi,Ali Akbar Babaei,Zeinab Baboli,Mohsen Hosseinzadeh 대한토목학회 2017 KSCE JOURNAL OF CIVIL ENGINEERING Vol.21 No.1

Finding a suitable site to dispose solid waste is a difficult task for municipality because it is necessary to consider the different factors and criteria in the landfill siting process. In this study, in order to consider all parameters, a combination of Geographic Information System (GIS) and the Analytic Hierarchy Process (AHP) was used for landfill site selection. For the purpose of making decisions in landfill site selection a hierarchy structural was formed and different parameters have been identified, including distance to groundwater, distance to surface water, sensitive ecosystems, land cover, distance to urban and rural areas, land uses, distance to roads, slope, soil type and distance to waste generation places. At first, the rating method was used to evaluate each criterion individually. Then, the relative importance of criteria to each other was determined by an analytic hierarchy process (AHP). Simple Additive Weighting (SAW) method was applied to evaluate the land suitability. The results showed that 38% of the study area have high suitability for land filling. Finally, five sites were a candidate for field investigation with more details.

A Cascaded Modular Multilevel Inverter Topology Using Novel Series Basic Units with a Reduced Number of Power Electronic Elements

Reza Barzegarkhoo,Naser Vosoughi,Elyas Zamiri,Hossein Madadi Kojabadi,Liuchen Chang 전력전자학회 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.6

In this study, a new type of cascaded modular multilevel inverters (CMMLIs) is presented which is able to produce a considerable number of output voltage levels with a reasonable number of components. Accordingly, each series stage of the proposed CMMLI is comprised of two same basic units that are connected with each other through two unidirectional power switches without aiming any of the full H-bridge cells. In addition, since the potentiality for generating a higher number of output voltage levels in CMMLIs hinges on the magnitude of the dc voltage sources used in each series unit, in the rest of this paper, four different algorithms for determining an appropriate value for the dc sources’ magnitude are also presented. In the following, a comprehensive topological analysis between some CMMLI structures reported in the literature and proposed structure along with several simulation and experimental results will be also given to validate the lucrative benefits and viability of the proposed topology.

Effect of Co-Driver on Job Content and Depression of Truck Drivers

Ali Hatami,Shahram Vosoughi,Agha F. Hosseini,Hossein Ebrahimi 한국산업안전보건공단 산업안전보건연구원 2019 Safety and health at work Vol.10 No.1

Background: Since the presence of a co-driver can be considered as a companion, partner, or friend for a driver through eliminating driver’s loneliness, it plays a significant role in health and safety of drivers. The objective of this study was to investigate the effect of co-drivers on depression and occupational stress on male truck drivers. Methods: This study was an interventional case-control study. Seventy truck drivers were selected and divided into two groups: case (33 truck drivers with co-drivers) and control (37 truck drivers without codrivers). Two Goldberg depression inventories (for evaluating driver’s depression) and the Karasek job content questionnaire (for evaluating driver’s job stress) were used to collect data which were completed by interview. Results: The results showed that job content values for the case group were higher in all dimensions except job nature. The comparison of the percentages showed significant difference between two groups. Depression rate in drivers with co-driver is truly less than depression rate in drivers without co-driver. There was significant positive relationship between dimensions of job content and depression rate. Conclusion: According to the results of this study, it can be claimed that a co-driver decreases stress and loneliness of drivers, as well as increases work performance and job satisfaction, and, in turn, leads to a decrease in job-related depression.