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Mahdi Toroski,Shekoufeh Nikfar,Mohammad Mahdi Mojahedian,Mohammad Hosein Ayati 사단법인약침학회 2018 Journal of Acupuncture & Meridian Studies Vol.11 No.2
Introduction and objectiveChronic low back pain (CLBP) is among the most common and important reasons for visiting a spine surgeon by patients; it is the second cause of visiting a doctor. Low back pain can cause considerable suffering and is a major financial burden in the society. There are many different methods available for the treatment of CLBP. This study aimed to compare the cost-utility of electroacupuncture (EA) and nonsteroidal antiinflammatory drugs (NSAIDs), as two common treatment methods for patients with CLBP. MethodsThis study was conducted on 100 patients suffering from CLBP. Cases were randomly selected from patients referring to two hospitals and four acupuncture clinics in Tehran. Forty-one patients received EA, and 59 patients were prescribed NSAIDs. The EuroQol five dimensions questionnaire was used to calculate quality-adjusted life-year. For calculating the total cost of the two treatment methods, face to face interview with patients was conducted by the researchers (using specific basic literature questionnaire), neurologists, and spine surgeons. The study perspective was social (direct and indirect costs calculated). ResultsThe mean age for EA group was 41 ± 2.3 years, and for NSAIDs group, it was 38.0 ± 4.4 years. The average of the utility of patients under treatment by EA and NSAIDs was estimated as 0.70 and 0.627, respectively. The difference in utility between the two groups was significant (p ≤ 0.05). The total cost of EA and NSAIDs was estimated as 461.48 ± 57.8$ and 497.77 ± 85.2$ for one year (2016), respectively, which was also significant (p ≤ 0.05). ConclusionThe results indicate a significant difference between EA and NSAIDs in cases of both utility and total cost. The findings demonstrate that EA is more cost-effective than NSAIDs, as therefore can be considered as an alternative treatment for CLBP, with reasonable cost-utility.
Reliable modeling of discharge process for adsorbed natural gas storage tanks
Mahdi Khorashadizadeh,Akbar Shahsavand,Mahdi Niknam Shahrak 한국화학공학회 2014 Korean Journal of Chemical Engineering Vol.31 No.11
Natural gas consumption has doubled in the last fifteen years. Among all storage techniques, adsorbednatural gas (ANG) provides a reliable vehicle for safe utilization of natural gas. Despite all favorable characteristicsof the ANG process, thermal adverse effects during charge and discharge processes are the most challenging issuesfacing adsorbed natural gas applications, especially for automotive usage. Mathematical modeling of an ANG tankcan provide a reliable method to analyze and solve such problems. A robust and lumped model is presented to mimicthe discharge process of an ANG tank storing pure component. The proposed model is very convenient compared toother available conventional models that require extensive computational efforts. Two experimental measurements andtwo simulation data sets (borrowed from literature) are recruited to validate the model predictions. The simulation resultsindicate proper agreement between the proposed model predictions and the validation data.
Mahdi Vahidpour,Ali Kheyroddin,Mahdi Kioumarsi 한국콘크리트학회 2022 International Journal of Concrete Structures and M Vol.16 No.3
The main objective of this study is to investigate the structural performance of reinforced concrete (RC) beam specimens strengthened with 3D-fiberglass as compared with fiber-reinforced polymers (FRP) sheets. For this purpose, six RC beams were fabricated, strengthened, and tested under a four-point bending machine. One of the beams served as the control beam (REF), while the others were strengthened with carbon FRP (RCFRP), glass FRP (RGFRP), 3D-fiberglass and epoxy resin (R3DTR), 3D-fiberglass and epoxy resin extended to the sides (R3DTRB), and 3D-fiberglass and concrete repair (R3DTG). Failure mode, crack development, flexural capacity, ductility, the effectiveness of wrapping configurations, and the performance of epoxy resin in comparison with concrete repairer were studied between various beams. The results attest to the better performance and effectiveness of 3D-fiberglass over FRP in terms of flexural capacity, crack pattern, and ductility. The R3DTR and RGFRP specimens, compared to the control specimen, had the highest and lowest flexural capacity growth, with 19% and 8.4%, respectively. In addition, the failure modes observed in this study were in good agreement with the failure modes present in ACI.440.2R-17. Moreover, finite element (FE) models were proposed to predict the residual capacity of the specimens strengthened with FRP, using Abaqus software.
Association between Corporate Governance and Corporate Performance in Iran
Mahdi Moradi,Mahmood Mousavi Shiri,Mahdi Salehi,Habib Piri 한국유통과학회 2013 유통과학연구 Vol.11 No.11
Purpose Considering corporate companies that are continually growing and bearing in mind the theory of agency, how confident can stakeholders be about their benefits in relation to managers’decisions? Previous research has indicated that the type of corporate governance can have an effective impact on companies’ performance. The current study aims to investigate the impact of ownership structure on listed companies on the Tehran Stock Exchange. Research Design, Data, and Methodology Through use of the correlation coefficient, the results indicate a positive correlation among the percentage of common stock held by board members, the percentage of non-executive board members, and separation of the positions of chairperson of the board of directors and managing director. Results Based on the return on assets index, only the correlation between the proportion of ownership of the managing director and financial investment company ownership is significant. Conclusion Managers can potentially make decisions that –benefit themselves but are detrimental to shareholders' interests. Corporate governance is a factor that can mitigate agency costs. Corporate governance comprises the laws, regulations,structures, processes, cultures, and systems that lead to the achievement of objectives such as accountability, transparency,justice, and stakeholders' rights.
Vibration analysis of rotating beam with variable cross section using Riccati transfer matrix method
Mahdi Feyzollahzadeh,Mahdi Bamdad 국제구조공학회 2019 Structural Engineering and Mechanics, An Int'l Jou Vol.70 No.2
In this paper, a semi-analytical method will be discussed for free vibration analysis of rotating beams with variable cross sectional area. For this purpose, the rotating beam is discretized through applying the transfer matrix method and assumed the axial force is constant for each element. Then, the transfer matrix is derived based on Euler-Bernoulli’s beam differential equation and applying boundary conditions. In the following, the frequencies of the rotating beam with constant and variable cross sections are determined using the transfer matrix method in several case studies. In order to eliminate numerical difficulties in the transfer matrix method, the Riccati transfer matrix is employed for high rotation speed and high modes. The results are compared with the results of the finite elements method and Rayleigh-Ritz method which show good agreement in spite of low computational cost.
Failure analysis of unidirectional polymeric matrix composites with two serial pin loaded-holes
Mohammad Mahdi Attar,Farzan Barati,Mahdi Ahmadpour,Ehsan Rezapour 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.6
The objective of this study is to investigate the effects of geometrical and physical parameters on failure modes and failure loads in unidirectional polymeric matrix composites with two serial pin loaded holes, analytically and experimentally. It is assumed that all of unidirectional fibers in the laminate lie in one direction while loaded by a load p 0 at infinity, parallel to the direction of the fibers. To derive equilibrium equations based on a Shear-Lag theory, a rectangular arrangement of fibers is considered and with the proper use of boundary and boundness conditions, stress and displacement fields are computed within the laminate, along with the surrounding pinholes. Finally by using the Hashin criterion failure modes and failure loads are estimated. To validate analytical results based on shear-lag theory, an experimental program is carried out. A very good agreement is observed between two procedures. Based on results, in small sizes of two pins, the dominant failure mode is bearing and with the increasing of hole sizes, failure modes are changed to tension and shear modes.
Mohammad Mahdi Naserian,Mahdi Fahiminia,Hamid Reza Goshayeshi 대한기계학회 2013 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.27 No.7
In the present study, the natural convection heat transfer coefficient from V-type fin-arrays on a vertical base is investigated both experimentally and numerically. The CFD simulations are carried out using Fluent software. The investigated cases consist of different shapes of a 90-degree V-type fin which are broken into discrete pieces instead of being an integrated fin. The number and shape of pieces as well as the gap between them is studied for different cases. By scrutinizing the results, an optimum fin shape on a vertical base is determined. In addition, the optimum V-type fin array is introduced by studying the number of rows for the optimum fin shape. Finally, a correlation is presented which relates the Nusselt number with the modified Rayleigh number.