Papers by Keyword: MRT

Abstract: This article presents a comprehensive numerical study of natural convection in a water-filled triangular cavity using the multi-relaxation time lattice Boltzmann method (MRT-LBM). The main objective of this study is to thoroughly analyze the influence of the heated chip's position along the left wall and the Rayleigh number on crucial aspects such as isotherms, streamlines, velocity, and temperature profiles, as well as the Nusselt number. In this setup, the hypotenuse wall is kept completely cold, while the other parts of the left wall and the bottom wall are adiabatic. Simulations are conducted for three different positions of the heated chip, with Rayleigh numbers, Ra, set at 10³ and 10⁵. The results of these investigations reveal that the heating position plays a crucial role in optimizing control, providing significant implications for various applications. Validation results demonstrate satisfactory agreement with existing literature, reinforcing the robustness and reliability of our numerical approach based on MRT.

Abstract: For this paper, we analyze the achievable sum rate of zero-forcing (ZF) pre-coding and Maximum Ratio Transmission (MRT) pre-coding with Matrix Normalization in massive MIMO system with Imperfect CSIT. We compare the performances of these two pre-codings and find that ZF pre-coding outperforming MRT pre-coding in the high SNR region while MRT pre-coding outperforming ZF pre-coding in the low SNR region. Then we derive the threshold of the pre-coding selection and provide the procedure of pre-coding schemes selection.

Abstract: The Lattice Boltzmann Method (LBM) is a potent numerical technique based on kinetic theory, which has been effectively employed in various complicated physical, chemical and fluid mechanics problems. In this paper multi-relaxation lattice Boltzmann model (MRT) coupled with a Large Eddy Simulation (LES) and the equation are applied for driven cavity flow at different Reynolds number (1000-10000) and the results are compared with the previous published papers which solve the Navier stokes equation directly. The comparisons between the simulated results show that the lattice Boltzmann method has the capacity to solve the complex flows with reasonable accuracy and reliability. Keywords: Two-dimensional flows, Lattice Boltzmann method, Turbulent flow, MRT, LES.

Abstract: On the basis of compliant polishing device for aspheric, a new method of bonnet polishing on magneto-rheological of torque servo driver has been proposed. It has introduced the bonnet polishing composition and polishing principle. Polishing tool using the flexible bonnet, it can better adapt to the different curvature change of parts, and the stable polishing force can be get through MRT. Combining the constant torque device on MRF with CNC machine, this embodies high rigidity, higher precision of NC machine and reflects the MRT with adjustable, controllable, rapid response characteristics. The formulae of stress and relative velocity of polishing are deduced, and the material removal rate model has been set up. The experimental results show that this new method of bonnet polishing can provide stable polishing force, and the model is correct, has good prediction ability.

Abstract: Guest diffusion in nanoporous materials reveals a wide spectrum of phenomena associated with random mass transfer in condensed matter quite in general. Taking advantage of their potentials for monitoring mass transfer over microscopic dimensions, micro-imaging (by interference microscopy and IR spectroscopy) and pulsed field gradient (PFG) NMR are exploited for providing typical examples highlighting these options. Starting with the surprise provided by the application of these microscopic measuring techniques to nanoporous materials, namely discrepancies of up to five orders of magnitude in comparison with the so far well-established data, the review covers some of the most impressive further results, including the determination of sticking coefficients on the surfaces of these materials and the specification and detection of conditions where molecular mass transfer is accelerated rather than hampered by counter fluxes.

Abstract: According to past experiences, the collapse of tunneling work always triggered a chain reaction of collateral damage and caused a considerable urban impact. Therefore, while the tunnel disasters occur, the timely response is important to prevent the expansion of the disaster and the subsequent restoration work is equally important to shorten the impact duration and ensure the ultimate success of the project. This study used the restoration works of a tunneling failure that occurred in Kaohsiung MRT project as a research subject to identify those works, which are critical to the success in the process of the restoration. The research results suggest that an accurate site investigation, and a thorough analysis of possible alternatives and the selection of restoration methods with comprehensive consideration of various factors are the critical factors for the success of the restoration works.

Abstract: Major metropolitan transportation construction works usually employ underground tunneling methods and carry great risks. According to past experiences, the collapse of tunneling works always triggered a chain reaction of collateral damage and caused a considerable urban impact. Therefore, the damage control and restoration in the event of MRT tunneling failure have drawn great attention of researchers and industrial practitioners. This study used the tunnel collapse of the Kaohsiung MRT project as a research subject. The project was executed by a JV entity through an international joint venture between a Taiwanese and a Japanese construction firm. Conclusions are made based on the analysis of information collected from written documents and in-depth interviews with people involved in the remedial and restoration works. This study discusses the series of measures taken for the collapse event in question, and may serve as a reference to highlight the importance of disaster prevention for future.

Abstract: Magnetorheological fluid torque servo (MRT) is a novel torque generating and controlling device. It converts the rotational input of active shearing disc into the torque output of passive shearing disc by controlling the rheological property of the magnetorheological fluid. In this paper, the working principle of the MRT was introduced. The effects of the input rotational speed on the shear stress of the magnetorheological fluid and then the output torque were analyzed. The model describing the relationship of the output torque with respect to the rotational speed of the active shearing disc as well as to other parameters was established. A critical rotational speed was deduced. The factors affecting the critical speed were discussed, and an experiment was conducted to ascertain the validity of the theoretical analysis.

Abstract: In this paper, a NC compliant abrasive polishing system was developed based on a magnetorheological torque servo (MRT), using a bonnet as the polishing tool. The MRT was uesd to provide a load acting on bonnet tool to produce the polishing force. In order to find the factors affecting the polishing quality, the models of the applied load, polishing force and contact pressure between the bonnet and the part were established based on Hertz theory, and the factors affecting the contact pressure were analyzed. Theoretical analysis indicated that there was a significant effect of the applied load, the initial pressure of the bonnet and the radius of curvature of the part on contact pressure. Experiments were carried out to verify the validity of the models, and experiment results showed that the roughness of the part was improved greatly and the polishing efficiency could be controlled by changing the initial pressure of the bonnet and applied load.

Abstract: In this paper, a compliant tool was designed for abrade polishing parts with surface of revolution on general NC lathe. The tool can adapt itself automatically to the part’s surface. A magnetorheological torque servo driver (MRT) was developed to control independently the polishing force between the tool and the surface which determines the contact pressure and affects the polishing quality. The models of polishing force and contact pressure were established based on Hertz theory. The model of tool head posture was deduced. The impact of tool head posture and position on contact pressure was analyzed. The experiment results verified the validity of the compliant tool and models.