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Zhen-yuan Jia,De-Ning Song,Jian-Wei Ma,Xiao-Xuan Zhao,Ning Zhang 한국정밀공학회 2018 International Journal of Precision Engineering and Vol.19 No.2
It is crucial to control the contour error in curved contour-following tasks caused by reasons such as servo delay and external disturbance. Contour-error estimation plays as a precondition for its further control. Existing methods can hardly keep well estimation accuracy for high-speed following of free-form curves with sharp corners, especially for three-dimensional curves. Consequently, this paper presents three high-precision real-time contour-error estimation methods for spatial free-form parametric curved contour following. By generating and updating the backstepping point according to the tangential tracking error, a multiple tangential approximation method is presented first. Then, a spatial circular approximation method is given by means of approximating the actual-position nearby region of the desired contour with a spatial circle. Finally, via modification of the Newton method so as to improve its stability without sacrificing of its fast convergence property, an initial value regeneration-based Newton algorithm is proposed for contour-error estimation. All of the presented methods take both estimation precision and calculation burden into consideration, and possess their own advantages. Using these algorithms, the contour error can be rapidly estimated in vector form with a high accuracy. Simulation and experimental results demonstrate the feasibility and the superiority of the presented algorithms.
ZHEN-Zhong Yuan(원진중),Eui-Chul Jung(정의철),Hee-Chang LIM(임희창) 대한기계학회 2013 대한기계학회 춘추학술대회 Vol.2013 No.5
?;?;Since there has been a rapid progress to understand the dynamics of an offshore floating body under an ocean environment, we undertake to generate the ocean waves in a lab-scale wind-wave flume. The study is aiming to observe and optimize the similar ocean environmental condition as input wave and to reduce the wall reflective wave. Several absorption methods are suggested to optimize the propagate wave by measuring the maximum and minimum of the standing wave envelope. There has been no optimized absorption method, as they highly depend on the wave period and the wave length. One of the methods-two fixed wave gauges measuring two wave heights and one wave phase ? is applied in this study. In the present paper various approaches were used to analyze the results using the flume, by position of probes, with absorber and without absorber, different position, condition and angle of the wave absorber, This paper also focuses on the analysis of fundamental equations which describe the separating method of the incident and reflective wave, and finally we confirm that the wave absorber is highly efficient considering all the permutation and combination. From the study it is clear that there is a change in the wave amplitude at the receiving end then the generated end; wave absorber is a strong source to control the energy of the coming wave. With the changing the period of the wave, the reflectance is increasing when the period becomes larger.
Zhen-yuan Gu,Shu-guang Wang,Weiqing Liu,Dong-sheng Du,Wei-zhi Xu 한국강구조학회 2017 International Journal of Steel Structures Vol.17 No.4
Based on the shaking table test of 1:20 scale structural models of the large-span isolated and non-isolated flat grid structures under the action of horizontal-bidirectional (2D) and three-dimensional (3D) rare earthquake, the dynamic characteristics, including natural vibration frequency, damping ratio, the acceleration and displacement responses are investigated. The results show that the base isolation could significantly prolong the structural vibration periods and increase the damping ratio. The capacity of energy dissipation for the base-isolated structure can also be improved. The horizontal acceleration amplification factors (AAFs) of the structure can be reduced greatly due to the base isolation, which effectively reduces the vertical vibration of the large-span grid. Under the 3D seismic input, the horizontal AAF of each layer is greater than that under the 2D one, which illustrates that the vertical seismic input increases the horizontal dynamic response of the structure. Furthermore, the finite element models of the isolated and non-isolated structures were simulated. The experimental results are in good agreement with the numerical results. The parameter optimization of isolation bearings was conducted by using finite element software. The seismic response of each layer under different shear to weight ratios (μ) was analyzed. It can be found that the parameters of the isolation layer have an optimal range which makes the dynamic response of the structure reach a minimum value under the rare earthquake.
Optimum design of Wave Absorber in Various Sinusoidal Propagating Wave
Zhen-Zhong Yuan(원진중),Hee-Chang LIM(임희창) 대한기계학회 2013 대한기계학회 춘추학술대회 Vol.2013 No.12
Since there has been a rapid progress to understand the dynamics of the coastal wave under a sloping-wall-type breakwater, we undertake to simulate the coastal waves and wave absorbers in a lab-scale wave flume. The study is aiming to observe and optimize a similar ocean environment and to reduce the wall reflection in the wave flume. In order to generate the ocean waves in the wave flume, the combination of the flat-type wave generator and wave absorbers is installed at the channel. Two probes for measuring the wave heights (i.e., level gauges) are used to observe the temporal variation of wave surface as well as the phase difference and the maximum (crest)/minimum (trough) points between the propagating waves. In order to optimize the shape and size of propagating waves, several absorption methods are proposed ?vertical-porous-plates absorber, horizontal punching plates absorber, sloping-wall-type wave absorber and active wave absorption, but for the better option of the propagating waves, the sloping-wall-type wave absorbers are chosen and tested in terms of the constitutive filling materials and the location and shape of the frame. This paper also focuses on the theoretical prediction of the wave surface separating them into incident and reflective components. In the result, it clearly shows that the wave absorber with hard filling material has better performance than that of soft material; i.e., wave absorber can be a strong sink to control the energy of the coming wave. In addition, the larger wave absorber becomes, the lower the reflectance be since the larger volume can remove the on-coming wave energy better. Therefore, given that the same condition of absorber is provided, the reflectance becomes bigger as the wave period is longer. Finally, the reflectance of wave would be controlled under 0.1 in this study so that the wave flume would be applied for simulating the offshore environment.
Decolorization of Aqueous Caprolactam Solution by Anion-exchange Resins
Yuan Zhen,Yu Ping,Luo Yunbai The Korean Fiber Society 2006 Fibers and polymers Vol.7 No.2
Caprolactam is the most important raw material for making Nylon 6 fibers and its quality directly determines the quality of Nylon. So it is necessary to study the techniques and methods to remove the colorful impurities from caprolactam. In this paper, the decolorization of caprolactam aqueous solution by anion exchange resins was studied and the decoloring abilities of five commercial resins were investigated. The regeneration of the resins was also studied, too. This study shows that the resin AMTX202 have excellent decoloring ability in the column experiment and that the decoloring efficiency is correlated with the volume of resins packed and is slightly affected by the flow rate and regenerating times. The fact that the resins can be regenerated and reused without affecting the efficiency of decolorization will decrease the cost of the treatment and operation in the industry. The adsorption of colored compounds with anion exchange resins in the packed columns seems to be technically feasible.
Preparation and activity evaluation of chrysin-b-Dgalactopyranoside
Zhen-Yuan Zhu,Ling Chen,Fei Liu,Li-Jing Chen,Meng Meng,Hui-Qing Sun,Yong-Min Zhang 대한약학회 2016 Archives of Pharmacal Research Vol.39 No.10
Chrysin-b-D-galactopyranoside was efficiently synthesized, evaluated for its inhibitory activities against H22 cell lines compared with chrysin, the scavenging of hydroxyl radical, DPPH radical and superoxide anion, inhibitory effect against bacteria and fungi. The structures of all compounds were fully characterized by spectroscopic data (NMR, MS). The anti-tumor, antioxidant and antimicrobial activities of chrysin-b-D-galactopyranoside were proved to be enhanced significantly compared with chrysin.
Shasha Yuan,Jinxing Liu,Junliang Shang,Xiangzhen Kong,Qi Yuan,Zhen Ma 대한의용생체공학회 2018 Biomedical Engineering Letters (BMEL) Vol.8 No.4
Since epileptic seizure is unpredictable and paroxysmal, an automatic system for seizure detecting could be of greatsignificance and assistance to patients and medical staff. In this paper, a novel method is proposed for multichannel patientspecificseizure detection applying the earth mover’s distance (EMD) in scalp EEG. Firstly, the wavelet decomposition isexecuted to the original EEGs with five scales, the scale 3, 4 and 5 are selected and transformed into histograms andafterwards the distances between histograms in pairs are computed applying the earth mover’s distance as effectivefeatures. Then, the EMD features are sent to the classifier based on the Bayesian linear discriminant analysis (BLDA) forclassification, and an efficient postprocessing procedure is applied to improve the detection system precision, finally. Toevaluate the performance of the proposed method, the CHB-MIT scalp EEG database with 958 h EEG recordings from 23epileptic patients is used and a relatively satisfactory detection rate is achieved with the average sensitivity of 95.65% andfalse detection rate of 0.68/h. The good performance of this algorithm indicates the potential application for seizuremonitoring in clinical practice.