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Beirami, Mohammadamin,Lee, Hee Yong,Yu, Yung-Ho The Korean Society of Marine Engineering 2015 한국마린엔지니어링학회지 Vol.39 No.5
This paper deals with development of an autopilot system for leisure yacht based on NMEA 2000 network and android platform. The developed system can operate both for manual steering and automatic navigation mode. In automatic steering mode, after manipulation of commands which are NMEA 0183 sentences by android platform, the developed system translates and sends the packets through NMEA 2000 network. Then the controller which is connected to NMEA 2000 network receives the commands and controls the boat's rudder system automatically. The automatic steering mode is achieved by cooperation of two controllers; one for controlling the rudder system, and the other for controlling the vessel's heading. To control the vessel's rudder and heading angle two PID controllers are developed with an adjustable dead-band gain. Also, in order to eliminate the steady-state error occurred by applying dead-band, an integral controller which specifically supervises the system's behavior inside the dead-band area is developed. In this paper, at the first stage, simulations are accomplished using computer in order to examine the feasibility of the proposed based on simulation results. In the next step, the system on a real hydraulic steering model is implemented and at the end the performance examination by implementing it on a real boat and doing test navigation is executed.
A Scalable HW-Based Inline Deduplication for SSD Arrays
Ajdari, Mohammadamin,Park, Pyeongsu,Kwon, Dongup,Kim, Joonsung,Kim, Jangwoo IEEE 2018 IEEE computer architecture letters Vol.17 No.1
<P>SSD arrays are becoming popular in modern storage servers as a primary storage, and they aim to reduce the high cost of the devices by performing inline deduplications. Unfortunately, existing software-based inline deduplications cannot achieve the devices’ maximum throughput due to their high CPU utilization and power overhead. A recently proposed approach to perform device-wide deduplications inside each SSD can distribute the CPU overhead among multiple SSDs, but it also suffers from severely decreasing deduplication opportunities with the increasing number of SSDs deployed per node. Therefore, we propose a node-wide deduplication engine that relies on specialized hardware to perform two key steps of deduplication; data signature generation and table management. Our FPGA-based prototype detects all duplicates, and compared to software-based inline deduplication, it reduces the overall CPU utilization and power consumption by 93.6 and <TEX>$\sim$</TEX><alternatives> </alternatives>20 percent respectively for a slow baseline and more for faster baselines.</P>
Development of 3D Terrain Visualization for Navigation Simulation using a Unity 3D Development Tool
Shin, Il-Sik,Beirami, Mohammadamin,Cho, Seok-Je,Yu, Yung-Ho The Korean Society of Marine Engineering 2015 한국마린엔지니어링학회지 Vol.39 No.5
3D visualization of navigation simulation is to visualize the environment conditions (e.g. nearby ships, dynamic characteristics, environment, terrain, etc) for any users on ships at sea. Realistic 3D visualization enables the users to be immersed to it and guarantees the reliability of the simulation. In particular, terrain visualization contains many virtual objects, so it is time and cost-intensive for object modelling. This paper proposes a 3D terrain visualization method that can be realized in a short time and with low cost by using the Unity 3D development tool. The 3D terrain visualization system requires bathymetric and elevation terrains, and Aids to Navigations (AtoNs) to be realized. It also needs to include 3D visualization objects including bridges, buildings and port facilities for more accurate simulation. Bathymetric and AtoN elements are acquired from ENC, and the elevation element is acquired from SRTM v4.1 digital elevation chart database developed by NASA. Then, the bathymetric and elevation terrains are generated, and the satellite images are superposed by using this terrain information. The longitudinal and latitudinal information of the AtoNs are converted to the 3-axis information to position the AtoN locations. The 3D objects such as bridges, buildings and port facilities are generated and the terrain visualization is completed. The proposed method realizes more realistic 3D terrain visualization of Busan Port.
Multi-objective optimization of tapered tubes for crashworthiness by surrogate methodologies
Masoud Asgari,Alireza Babaee,Mohammadamin Jamshidi 국제구조공학회 2018 Steel and Composite Structures, An International J Vol.27 No.4
In this paper, the single and multi-objective optimization of thin-walled conical tubes with different types of indentations under axial impact has been investigated using surrogate models called metamodels. The geometry of tapered thin-walled tubes has been studied in order to achieve maximum specific energy absorption (SEA) and minimum peak crushing force (PCF). The height, radius, thickness, tapered angle of the tube, and the radius of indentation have been considered as design variables. Based on the design of experiments (DOE) method, the generated sample points are computed using the explicit finite element code. Different surrogate models including Kriging, Feed Forward Neural Network (FNN), Radial Basis Neural Network (RNN), and Response Surface Modelling (RSM) comprised to evaluate the appropriation of such models. The comparison study between surrogate models and the exploration of indentation shapes have been provided. The obtained results show that the RNN method has the minimum mean squared error (MSE) in training points compared to the other methods. Meanwhile, optimization based on surrogate models with lower values of MSE does not provide optimum results. The RNN method demonstrates a lower crashworthiness performance (with a lower value of 125.7% for SEA and a higher value of 56.8% for PCF) in comparison to RSM with an error order of 10<sup>-3</sup>. The SEA values can be increased by 17.6% and PCF values can be decreased by 24.63% by different types of indentation. In a specific geometry, higher SEA and lower PCF require triangular and circular shapes of indentation, respectively.
Basilar Skull Fractures and Their Complications in Patients With Traumatic Brain Injury
Mehdi Shafiei,Bahram Aminmansour,Mehdi Mahmoodkhani,Mohammadamin Seyedmoalemi,Donya Sheibani Tehrani 대한신경손상학회 2023 Korean Journal of Neurotrauma Vol.19 No.1
Since traumatic brain injury is more common in young people, who are the main workforce and builders of society, it is important to consider the effects caused by brain injury on them. In this study, we investigated the clinical manifestations, complications, and prognosis of patients with basilar skull fractures.
Mohammad Mahdi Vashghani Farahani,Reza Ahadi,Mohammadamin Abdollahifar,Mohammad Bayat 한국실험동물학회 2017 Laboratory Animal Research Vol.33 No.1
Previous studies report positive effects of pentoxifylline (PTX) alone or in combination with other drugs on some pathologic bone diseases as well as an ability to accelerate osteogensis and fracture healing in both animal models and human patients. The aim of this present study was to evaluate the effects of PTX administration on Hounsfield unit and bone strength at catabolic response (bone resorbing) of a fracture in an experimental rat model of ovariectomy induced osteoporosis (OVX-D). Thirty adult female rats were divided into groups as follows: 1 (OVX, control, no treatment); 2 (OVX, sham: daily distilled water); 3 (OVX, daily alendronate: 3 mg/kg); 4 (OVX, twice daily 100 mg/kg PTX) and 5 (OVX, PTX+alenderonate). OVX was induced by bilateral ovariectomy in all rats. A complete standardized osteotomy of the right femur was made after 3.5 months. PTX and alendronate treatments were performed for eight weeks. Then, rats were euthanized and had its right femur subjected to computerized tomography scanning for measuring Hounsfield unit; eventually, the samples were sent for a three point bending test for evaluation of the bone strength. Administration of PTX with 200 mg/kg and alendronate alone and in combination showed no significant alteration in Hounsfield unit and biomechanical properties of repairing callus of the complete osteotomy compared with the control group. Results showed increased bending stiffness and stress high load mean values of repairing complete osteotomy in PTX-treated rats compared to the control OVX-D.
Abdoulreza Esteghamati,Shirin Sayyahfar,Hossein Ghaemi,Mohammadamin Joulani,Yousef Moradi,Atefeh Talebi 대한백신학회 2021 Clinical and Experimental Vaccine Research Vol.10 No.1
Purpose: The aim of this study was to compare the hepatitis B surface antibody (HBs Ab) titer 1 month after the 4th dose of hepatitis B vaccine administration on the large and appropriate for gestational age infants. Materials and Methods: This cross-sectional study was conducted on 7-month-old cases (n=132) divided into two groups of 2–4 kg (group 1: appropriate for gestational age, 63 cases) and >4 kg (group 2: large for gestational age, 69 cases), whom were vaccinated with a four-dose schedule of hepatitis B vaccine in 2016, Tehran, Iran. Results: Mean birth weight of the groups was 2.98±0.528 and 4.19±0.190 kg, respectively. Hepatitis B surface antigen and hepatitis B core antibody were negative in all cases. HBs Ab level in group 1 and 2 was 13,701.00±11,744.439 and 8,997.15±2,827.191, respectively (95% confidence interval of difference, -7,607.44 to -1,800.25). There was a significant difference between the two groups in antibody titration and antibody logarithm level (p=0.002, p=0.0001). Conclusion: Birth weight may affect the response to the hepatitis B virus vaccine administration.