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.

Increase in the Th1-Cell-Based Immune Response in Healthy Workers Exposed to Low-Dose Radiation - Immune System Status of Radiology Staff

Gholamreza Karimi,Mahdi Balali-Mood,Seyed-Ali Alamdaran,Hassan Badie-Bostan,Elaheh Mohammadi,Adel Ghorani-Azam,Mahmood Sadeghi,Bamdad Riahi-Zanjani 대한약침학회 2017 Journal of pharmacopuncture Vol.20 No.2

Objectives: Radiation is one of the most important sources of free radical (such as reactive oxygen species) production, which plays an essential role in the etiology of over hundred diseases. The aim of the study was to investigate some immune parameters and hematological indices in healthy workers of the Radiology Department, University Hospital of Mashhad, Iran. Methods: The study was performed on 50 healthy workers: 30 radiology staff as the case group and 20 laboratory workers as the control group. The radiation dose received by the radiology staff participating in the study was less than the annual maximum permissible level, 50 millisievert. Hematological parameters, lymphocyte proliferation and cytokine production were studied in both groups. Results: Among healthy radiology workers, the hematological indices did not differ statistically; however, their proliferation indices and IFN-γ levels showed significant increases in parallel with decreases in the IL-4 levels as compared to controls. The immune system of workers exposed to low-dose ionizing radiation was found to be shifted from a Type 2 to a Type 1 response to promote cellular immunity. Conclusion: Based on our data, exposure to low-dose ionizing radiation may decrease the prevalence, frequency, and recurrence of various cancers and infectious diseases because of an increase in Th1-cell-based response, thus leading to more protection of the human body against tumor cells and foreign agents and possibly increased longevity. However, due to high rate of fluoroscopy use for interventional radiology, we suggest continuing research projects on radiation protection and hazards to prevent irreversible damage. As a recommendation, in future studies, radiology staff with a weakened immunity due to high radiation exposure should be considered as good choices to be treated using acupuncture techniques because acupuncture has been demonstrated to enhance the function and the number of immune cells.

Design, Modeling and Control of a Simulator of an Aircraft Maneuver in the Wind Tunnel Using Cable Robot

Hami Tourajizadeh,Mahdi Yousefzadeh,Ali Keymasi Khalaji,Mahdi Bamdad 제어·로봇·시스템학회 2022 International Journal of Control, Automation, and Vol.20 No.5

In this paper, a new controllable simulator is proposed and modeled by which, experimental tests of the aircraft’s models can be performed in wind tunnels with a high level of accuracy. These tests are unavoidable in order to extract the aerodynamic characteristics of the plant and optimize its related profiles. Drag and lift coefficients of the aircraft have a significant effect on the static and also dynamic maneuver of the airplane and thus evaluating these characteristics before manufacturing the aircraft are highly valuable in order to optimize the profile of their structures. To realize the mentioned target experimental tests can provide more accurate and trustable results rather than computer simulations. In order to conduct the wind tunnel tests with the highest accuracy, it is extremely significant to decrease any source of error such as disturbing drag forces. Thus it is required to control and manipulate the model of the aircraft with the aid of a mechanism that not only has the minimum effect on the drag force but also provides the least amount of deviation corresponding to drag forces. To do so, in this paper, a new cable robot is proposed as a proper candidate mechanism by which the disturbing drag force of the tunnel wind is minimum as a result of exact control of all of six spatial Degrees of Freedom (DOFs). Also, cables have the least cross-section area against the wind force and therefore the error of disturbing drags could be minimized. Moreover, there are other advantages for these kinds of robots such as low weight and cost, high load carrying capacity, and easy assembling capability. By proper design of the cables and actuators, it is possible to control all of the degrees of freedom of the end-effector during the dynamic maneuver of the aircraft and so it possible to perform all of the required static and dynamic tests of the plant. Therefore, in this paper first, the proper mechanism is designed and its related kinematics and kinetics modeling is provided. Besides, a robust controller is designed based on Non-Singular Fast Terminal Sliding Mode (NFTSM) to control the aircraft maneuver in presence of wind disturbance and complete the test process. All of the mentioned claims are verified by MATLAB simulations and the results confirm the mentioned expectancies.

Decreased Levels of Spleen Tissue CD4+CD25+Foxp3+ Regulatory T Lymphocytes in Mice Exposed to Berberine

Gholamreza Karimi,Mahmoud Mahmoudi,Mahdi Balali-Mood,Maryam Rahnama,Shahrzad Zamani Taghizadeh Rabe,Nafiseh Tabasi,Bamdad Riahi-Zanjani 사단법인약침학회 2017 Journal of Acupuncture & Meridian Studies Vol.10 No.2

The effects of isoquinoline alkaloid berberine (BER) on spleen tissue CD4þCD25þFoxp3þ regulatory T (Treg) cells were evaluated in BALB/c mice. Here, BER was administered daily by intraperitoneal injection at doses of 5 mg/kg and 10 mg/kg for 14 days. Following the exposure, mice spleen cellularities, IL-10 production by splenocytes, and spleen Treg/CD4þ cell profiles were studied in all the test groups of animals. The results showed that a high dose of BER (10 mg/kg) could decrease both the absolute and relative percentages of spleen Treg cells as well as decrease the production of IL-10 by splenocytes in the treated mice (p < 0.05). BER at 5 mg/kg did not appear to affect any of these parameters. Based on the finding here, it would seem that BER has effective immunostimulatory properties, which contradicts the results from other studies indicating immunosuppressive effects of BER. Depending on the doses of BER used, it might have a broad spectrum from immunosuppressive to stimulatory effects. Further studies, including more doses, are required to better evaluate the effects of this natural product. Mechanistic studies are required, particularly in case of redox state of the immune cells, to elucidate and determine how BER functions to impart the toxicity effects demonstrated here and in other studies.

Application of Generalized Flexibility Matrix in Damage Identification using Imperialist Competitive Algorithm

Mehdi Masoumi,Ehsan Jamshidi,Mahdi Bamdad 대한토목학회 2015 KSCE JOURNAL OF CIVIL ENGINEERING Vol.19 No.4

In this article, a new objective function which is formed by using generalized flexibility matrix is presented with the aim of solving the constrained optimization problem in damage detection procedure. The main purpose is to decrease the effects of truncation error which ensue from cutting off the higher order modes. Two different case studies are used to evaluate the proposed approach. These cases include, a 2D-frame and a Howe-Truss structure. In this study, each structure is modeled by finite element method and damages are induced by considering a reduction in the stiffness of the elements. Finally, the inverse problem of damage identification is solved by using the Imperialist Competitive Algorithm (ICA) for each damage scenario. Not only the effect of noise on the obtained results is studied but also a comparison is drawn between the proposed method based on ICA and other conventional optimization algorithms, namely PSO and GA.

Increase in the Th1-Cell-Based Immune Response in Healthy Workers Exposed to Low-Dose Radiation - Immune System Status of Radiology Staff

Karimi, Gholamreza,Balali-Mood, Mahdi,Alamdaran, Seyed-Ali,Badie-Bostan, Hassan,Mohammadi, Elaheh,Ghorani-Azam, Adel,Sadeghi, Mahmood,Riahi-Zanjani, Bamdad KOREAN PHARMACOPUNCTURE INSTITUTE 2017 Journal of pharmacopuncture Vol.20 No.2

Objectives: Radiation is one of the most important sources of free radical (such as reactive oxygen species) production, which plays an essential role in the etiology of over hundred diseases. The aim of the study was to investigate some immune parameters and hematological indices in healthy workers of the Radiology Department, University Hospital of Mashhad, Iran. Methods: The study was performed on 50 healthy workers: 30 radiology staff as the case group and 20 laboratory workers as the control group. The radiation dose received by the radiology staff participating in the study was less than the annual maximum permissible level, 50 millisievert. Hematological parameters, lymphocyte proliferation and cytokine production were studied in both groups. Results: Among healthy radiology workers, the hematological indices did not differ statistically; however, their proliferation indices and $IFN-{\gamma}$ levels showed significant increases in parallel with decreases in the IL-4 levels as compared to controls. The immune system of workers exposed to low-dose ionizing radiation was found to be shifted from a Type 2 to a Type 1 response to promote cellular immunity. Conclusion: Based on our data, exposure to low-dose ionizing radiation may decrease the prevalence, frequency, and recurrence of various cancers and infectious diseases because of an increase in Th1-cell-based response, thus leading to more protection of the human body against tumor cells and foreign agents and possibly increased longevity. However, due to high rate of fluoroscopy use for interventional radiology, we suggest continuing research projects on radiation protection and hazards to prevent irreversible damage. As a recommendation, in future studies, radiology staff with a weakened immunity due to high radiation exposure should be considered as good choices to be treated using acupuncture techniques because acupuncture has been demonstrated to enhance the function and the number of immune cells.