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Influences of Pump Spot Radius and Depth of Focus on the Thermal Effect of Tm:YAP Crystal
Hongliang Zhang,Ya Wen,Lin Zhang,Zhen Fan,Jinge Liu,Chunting Wu 한국광학회 2019 Current Optics and Photonics Vol.3 No.5
The thermal effect and the light output of a laser crystal under different pumping depths were reported., Based on the thermal model of a single-ended pumped Tm:YAP crystal, the thermal stress coupled model used Comsol to theoretically calculate the effect of changing the pump spot size and pump depth on crystal heat distribution and stress distribution. The experimental results showed that the laser output power first increased and then decreased with increasing pump spot size. As the depth of focus increased, the laser output power first increased and then decreased. The experimental results were consistent with the theoretical simulation results. The theory of pump spot radius and depth of focus in this paper provided an effective simulation method for mitigating thermal effects, and provided theoretical supports for laser crystals to obtain higher laser output power.
A tunable dynamic vibration absorber for unbalanced rotor system
Hongliang Yao,Tongzhao Wang,Bang-chun Wen,Baijun Qiu 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.4
A tunable dynamic vibration absorber for unbalanced rotor system which is made up of coil springs and magnetic spring is presented. The structure of the absorber is introduced and the stiffness tuning mechanism of the magnetic spring is explained. A finite element model of the rotor-absorber system was built and the influencing factors to the appearance of the absorber were studied numerically. Finally, experiments were carried out to verify the numerical results, and PID control strategy was tested. The numerical and experimental results show that the present absorber is effective for vibration suppression of an unbalanced rotor system, and the control strategy is effective.
Vibration control of rotor system by ultrasonic excited limiter
Hongliang Yao,Qian Zhao,Hao Wu,Bang-chun Wen 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.5
We propose a novel method with an ultrasonically excited structure as a vibration limiter to control the vibration of rotor systems. Thefriction between the rotor and the limiter is significantly reduced by ultrasonic lubrication, thereby preventing the occurrence of rubbinginducedthermal bowing, which is commonly observed in traditional vibration limiters. In our study, the friction reduction mechanism ofthe ultrasonically excited vibration limiter was first examined based on tribology theory and Hertz contact theory. The vibration controleffects and the alleviation of thermal bowing were then investigated by numerical simulation. Finally, vibration control experiments wereperformed on a Bentley test rig with the ultrasonically excited vibration limiter. The consistency between theoretical and experimentalresults confirmed the effectiveness of the proposed method.
Pulsed-laser-diode Intermittently Pumped 2-μm Acousto-optic Q-switched Tm:LuAG Laser
Ya Wen,Yan Jiang,Hao Zheng,Hongliang Zhang,Chao Wang,Chunting Wu,Guangyong Jin 한국광학회 2020 Current Optics and Photonics Vol.4 No.3
The heat distribution in crystals in a 2-µm acousto-optic Q-switched Tm:LuAG laser pumped by pulsed-laser-diode (pulsed-LD) intermittent-pumping technology was analyzed using COMSOL software. The thermal lensing effect of the Tm:LuAG crystal can be mitigated by pulsed-LD intermittent-pumping techniques. An experimental setup using this kind of approach achieved maximum output energy of 8.31 mJ, minimum pulse width of 101.9 ns, and highest peak power of 81.55 kW, reached at a Q-switched repetition rate of 200 Hz. It offers significant improvement of performance of the output laser beam, compared to pulsed-LD double-ended pumping technology at the same repetition rate.
Prediction method for steady-state response of local rubbing blade-rotor systems
Qian Zhao,Hongliang Yao,Qi Xu,Bang-chun Wen 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.4
Blade-rotor systems frequently encounter the problem of blade-to-case rubbing, which affects their safety and stability. Numericalsimulation can be used to predict the steady-state response of these systems. However, such simulation is frequently computationallyexpensive because of the high dimensions of the dynamic model of a blade-rotor system. To overcome this problem, a new method thatcombines the receptance-based dimension-reduction approach with the incremental harmonic balance (IHB) method is presented in thisstudy. First, a dynamic model of a blade-rotor system is developed using the finite element method, and the number of dimensions of themodel is reduced by the receptance method. Subsequently, the steady-state response is obtained by the improved IHB method to convenientlymanage the large number of super-harmonic components of the local rubbing system. Finally, the precision and efficiency of theproposed method is verified by comparing its results with those obtained by the Newmark-b method. The proposed method is found to beefficient in analyzing local rubbing blade-rotor systems with high dimensions, local nonlinearities, and rich super-harmonics.
Yanru Yin,Changna Wen,Ning Ma,Baoyan Wang,Lianying Zhang,Hongliang Li,Peizhi Guo 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2019 NANO Vol.14 No.9
Palladium and palladium-silver bimetallic nanocrystals have been synthesized hydrothermally by using environmental-friendly sodium alginate as the stabilizer and reducing agent. The pure palladium nanoparticles were spherical-like possibly due to the principle of the lowest surface energy, however, the formation of bimetallic palladium-silver nanoparticles was much more complicated, which was thinner and more irregular nanostructures than pure palladium nanoparticles. Electrochemical measurements showed that the electrocatalytic activity toward ethanol oxidation was increased first with the increase of silver content in bimetallic nanoparticles, from pure palladium of around 1070 mA/mg, to PdAg-20 of 1160 mA/mg and to PdAg-10 of 1750 mA/mg, and declined greatly at a high content of silver, approximately 279 mA/mg. Electrochemical stability test showed that PdAg-10 and PdAg-5 were the best and worst among four palladium-based samples, respectively. Based on the experimental data, the formation mechanism of pure palladium and palladium-silver bimetallic nanoparticles and the structure-property relationship of these samples have been discussed.
Morphine-6-Glucuronide Isomers-Synthesis and Biological Evaluation
Jixia Yang,Guanyi Lu,Gongzheng Zhang,Xiaodi Wang,Hongliang Wen,Cipan Huang,Jiazhen Yin,Jin Li 대한화학회 2020 Bulletin of the Korean Chemical Society Vol.41 No.11
Morphine-6?-D-glucuronide (M6?G), an active metabolite of morphine, and its isomer morphine-6α-D-glucuronide (M6αG) were synthesized from 3-O-protected morphinethrough glycosylation and alkaline hydrolysis. All structures were determined by spectroscopic analysis, and especially it is the first time to report the single crystal of compound M6αG. In vitro binding assay showed that M6?G bound to mu opioid receptor (MOR), kappa opioid receptor (KOR), and delta opioid receptor (DOR) with nanomolar affinity (Ki = 28.03, 116.88, and 375.13?nM) and M6αG bound to them with similar affinity (Ki = 1070.13, 20?637.93, and 677.36?nM). The selectivity of M6αG toward KOR is much higher. Hot-plate test showed that the analgesic effect of M6?G is better than that of M6αG, that is maybe because the mechanism of M6αG is different.