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Tie Jun,Enmin Feng 한국전산응용수학회 2004 Journal of applied mathematics & informatics Vol.15 No.-
In this paper we study the problem of three-dimensional lay-out optimization on the simplied rotating vessel of satellite. The layoutoptimization model with behavioral constraints is established and someeective and convenient conditions of performance optimization are pre-sented. Moreover, we prove that the performance objective function islocally Lipschitz continuous and the results on the relations between thelocal optimal solution and the global optimal solution are derived.
Tie Jun,Jinzhi Wang,Enmin Feng 한국전산응용수학회 2008 Journal of applied mathematics & informatics Vol.26 No.1
This paper is motivated by the problem of fitting a group of cuboids into a simplified rotating vessel of the artificial satellite. Here we introduce a combinatorial optimization model which reduces the threedimensional layout problem with behavioral constraints to a finite enumeration scheme. Moreover, a global combinatorial optimization algorithm is described in detail, which is an improved graph-theoretic heuristic. This paper is motivated by the problem of fitting a group of cuboids into a simplified rotating vessel of the artificial satellite. Here we introduce a combinatorial optimization model which reduces the threedimensional layout problem with behavioral constraints to a finite enumeration scheme. Moreover, a global combinatorial optimization algorithm is described in detail, which is an improved graph-theoretic heuristic.
Secret Sharing-Based Chaotic Image Encryption
Tiejun Zhang,Aya El-Fatyany,Li Li,Mohamed Amin,Ahmed A. Abd El-Latif 보안공학연구지원센터 2015 International Journal of Security and Its Applicat Vol.9 No.7
This paper presents an image encryption scheme for secure digital images based on secret sharing and coupled map lattices. In this scheme, the secret image is encrypted before the sharing phase based on key sequences generated by chaotic map lattices. Experimental results and analysis show that the proposed scheme has better security and can be easily protects both confidentiality and loss-tolerance simultaneously in shadow images.
Modeling and Multivariable Control of a Novel Multi-Dimensional Levitated Stage with High Precision
Tiejun Hu,Won-jong Kim 대한전기학회 2006 International Journal of Control, Automation, and Vol.4 No.1
This paper presents the modeling and multivariable feedback control of a novel high-precision multi-dimensional positioning stage. This integrated 6-degree-of-freedom (DOF) motion stage is levitated by three aerostatic bearings and actuated by 3 three-phase synchronous permanent-magnet planar motors (SPMPMs). It can generate all 6-DOF motions with only a single moving part. With the DQ decomposition theory, this positioning stage is modeled as a multi-input multi-output (MIMO) electromechanical system with six inputs (currents) and six outputs (displacements). To achieve high-precision positioning capability, discrete-time integrator-augmented linear-quadratic-regulator (LQR) and reduced-order linear-quadratic-Gaussian (LQG) control methodologies are applied. Digital multivariable controllers are designed and implemented on the positioning system, and experimental results are also presented in this paper to demonstrate the stage's dynamic performance.
( Tiejun Miao ),( Xiaodong Yuan ),( Pingshu Zhang ),( Jun Song ) 한국감성과학회 2019 한국감성과학회 국제학술대회(ICES) Vol.2019 No.-
Healthy adults and patients with history of breathing disorders and stroke were enrolled in this clinical study and underwent simultaneous test by polysomnography (PSG). The present study analyzed fluctuation in vital signs and movement activity extracted from the multichannel ballistocardiographic signals based on piezo sensor distribution under bed mattress. We assessed the validity using contact less technology to screening obstructive sleep apnea and stroke. We found an agreement of apnea-hypopnea index (AHI) with the number of hypopneas estimated by our method. Also we found abnormal changes in body pressure distribution during sleep in patient having history of stroke. Mean area of distribution for stroke was 3.44±0.82 having significant lower values than ones without stroke who had value of 9.19±2.35.
Numerical Analysis of Two-Phase Flow in a Micro-Hydraulic Turbine
Tiejun Chen,Shuaihui Sun,Ye Pang,Pengcheng Guo 한국유체기계학회 2019 International journal of fluid machinery and syste Vol.12 No.4
In many industrial processes such as natural gas processing, seawater desalination et al, there is a large amount of liquid waste pressure energy, which can be converted into electric or mechanical energy by a micro-hydraulic turbine. But its efficiency and stability will deteriorate when the working fluid contains gas. Aiming at improving the hydraulic efficiency of the micro-turbine, the three-dimensional transient two-phase flow model which adopts the shear-stress-transport (SST) model as turbulence model and Eulerian-Eulerian model as two-phase flow model with the commercial code ANSYS-CFX was established and solved to study the two-phase flow characteristics of the micro-hydraulic turbine with fixed guide vane openings under different gas volume fraction (GVF). The numerical simulation results show that the power and efficiency of the turbine decrease by 24% and 21% respectively when the inlet GVF is 0.20. The area of low pressure in each impeller passage increases with the inlet GVF, and the pressure difference between the working and suction surface of the blade decreases. The GVF distribution in impeller passage is asymmetrical, which is caused by the gas-liquid separation in the volute. At the left lower part of impeller passage, the gas accumulates at the suction surface of the blades under the Coriolis force and its GVF reaches 90%. The asymmetrical GVF distribution will result in the asymmetrical pressure distribution in the impeller passage, which leads to the imbalance force on the blades. Moreover, the asymmetrical GVF distribution will reinforce the positive incidence at the lower part of impeller passage, and weaken it at the upper right impeller passage. The volute should be redesigned to ensure the uniform gas distribution at the inlet of each impeller passage.
Tiejun Wang,Weilan Wang 보안공학연구지원센터 2016 International Journal of Signal Processing, Image Vol.9 No.1
With the fast development of data analysis and computer science technology, the design and implementation of image retrieval system has been a hot topic. The prior research focus more on image-size based approaches which are not intelligent or convenient. In this paper, we present a novel modified evolutionary algorithm based image retrieval framework theoretically with applications. To achieve more accuracy in less number of iteration, this paper, proposed a new approach to enhance the performance of content guided retrieval methodology by improving the performance of RF through Particle Swarm Optimization, Genetic Algorithm and Support Vector Machine. The objective of using Genetic Algorithm and Particle Swarm Optimization is to increase the number of images in relevant set where SVM is used to classify the relevant and irrelevant images. The experimental and numerical simulation indicate the efficiency of our method which means the presented technique is helpful in the fields where high accuracy rate of image retrieval is required. Further work of interest is also discussed in the final section.
A Method Based on Spectrum Superposition for Minimizing the Hazards of Blasting Vibration
Tiejun Tao,Sipeng Wan,Liansheng Liu,Tongyan Pan 대한토목학회 2021 KSCE JOURNAL OF CIVIL ENGINEERING Vol.25 No.5
The selection of delay time will directly affect the effect of vibration reduction in millisecond delay blasting. The commonly used frequency spectrum control methods have some problems such as the difficulty of seed wave selection and the complexity of nonlinear superposition model. Based on the principle of waveform linear superposition, this study proposes a new spectrum superposition method for minimizing the vibration hazards in an open deep-hole bench blasting. This method, with no need to select the seed waves, mainly uses the ratio of the Fourier spectrum of the combined vibration waveform and the single hole vibration waveform to quantify the suppressed vibration. By defining the suppression ratio K, the suppression ratio with frequency range of 10 − 60 Hz under different delay times was calculated, and the theoretical optimal vibration reduction delay time value of 10 − 15 ms was given. A high precision digital electronic detonator was used to verify the proposed spectrum superposition method. The test results show that the best delay time of field vibration reduction is 5 − 10 ms, which is lower than the theoretical best delay time of 10 − 15 ms. It is the authors’ belief that this phenomenon is mainly caused by the joints and cracks in the rock mass, which will prolong the actual superposition time of blasting seismic waves between adjacent holes. In addition, it is found that there is a negative correlation between the delay time and the main vibration frequency, which is mainly caused by the low-pass filtering characteristic of rock medium. In order to minimize the probability of resonance failure, an optimal delay of 5 ms based on the main vibration frequency was given.