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Singularity-free path optimization of the parallel test mechanism for artificial hip joints
Huizhen Zhang,Gang Cheng,Xianlei Shan,Yang Li 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.4
This paper focuses on the singularity-free optimization for the working path of a 3SPS+1PS type parallel mechanism which is used for the simulation of hip joint motion. Kinematic and dynamic models of the test mechanism were set up with the vector method and the principle of virtual power, respectively. Based on the Jacobian matrix, the kinematic and dynamic performance evaluation indices were defined. The working path of the test mechanism traverses the singular surface twice. Optimization weas conducted with the attitude of the virtual reference coordinate system as the design variable, the mean value of the motion transmission performance index and the mean value and the standard deviation of the driving force in the working path as the optimization objectives, and the reachable workspace as the constraint condition. The equivalent working path of the test mechanism after optimization had no singularity. Moreover, the motion transmission performance improved evidently and the driving force changed smoothly.
Huizhen, Zhang,Zhen, Cui,Yizhi, Chen,Wei, Cui,Ping, Sheng,Manping, Zhang 목포해양대학교해사산업기술연구소 1997 심포지움강연논집 Vol.1997 No.11
The concentration of dimethylsulfide (DMS) and its metabolic precursor, dimethylsulfonio propionate (DMSP) in water and particulate samples obtained along transects through Jiaozhou Bay, China was determined. Here we report the distribution, diurnal change and seasonal variation of DMS and DMSP in water of Jiaozhous Bay and the adjacent area, including some of the biogeochemical factors controlling the distribution, change and variation. Eight individual clones of phytoplankton representing four classes were examined in exponential growth for DMS and KMSP by laboratory batch cultures. There is a strong correlation between the taxonomic position of the phytoplankton and the production of DKSP(DMS). The DMS and DMSP variation in growth and with variations in nutrient and salinity were reported.
Jie Song,Huizhen Wang,Chunjuan Zhang,Weifeng Liu,Yirong Shen 전력전자학회 2022 JOURNAL OF POWER ELECTRONICS Vol.22 No.2
The non-ideal factors such as the inherent chattering of a sliding mode observer (SMO), the delay of a control algorithm, and the dead-time effect give rise to the harmonic error of position estimation. To improve the performance of the position observation of high-speed permanent magnet synchronous motors (HSPMSMs), a wideband synchronous fundamentalfrequency extraction filter (WSFEF) is proposed. On this basis, a novel signal processing method consisting of a WSFEF-PLL is applied to extract the fundamental frequency signal of the estimated back electromotive force (EMF). The application of a phase-locked loop (PLL) ensures that the resonance frequency of the WSFEF is adaptive, which is essential for the variablespeed operation in sensorless HSPMSM drive systems. Using the WSFEF-PLL in a SMO-based position estimator, the rotor position estimation error caused by the harmonics contained in the back EMF can be effectively eliminated, which contributes to improving the accuracy and dynamic performance of the rotor position estimation. Simulations and experiments verify the feasibility and effectiveness of this method.
Mao Saijun,Wang Huizhen,Yan Yangguang The Korean Institute of Electrical Engineers 2005 KIEE International Transactions on Electrical Mach Vol.b5 No.4
This paper proposes a novel zero-voltage-switching (ZVS) Push-pull DC-DC Converter for high input voltage and high power applications. This topology utilizes two switches in series to replace one switch in conventional push-pull converter, and two clamping diodes are introduced. The voltage stress of the switches is the input voltage, and the switches can realize ZVS with the use of the leakage inductance of the transformer. Furthermore, secondary full-wave rectifier with a clamping capacitor is used to eliminate the voltage oscillation and spike of the rectifier diodes due to the reverse recovery. Therefore, the electromagnetic interference is reduced effectively. The operation principle of the proposed converter is analyzed theoretically. The output characteristic, ZVS condition and design principle of the clamping capacitor are discussed. Experimental results obtained from a 270V input 2kW prototype with $95.8\%$ high efficiency confirms the design.
Yaqi Cao,ZiFu Dai,Huizhen Lao,Huimin Zhao 대한수의학회 2022 Journal of Veterinary Science Vol.23 No.2
Background: The testis has been reported to be a naturally O2-deprived organ, dimethyloxaloylglycine (DMOG) can inhibit hypoxia inducible factor-1alpha (HIF-1α) subject to degradation under normal oxygen condition in cells. Objectives: The objective of this study is to detect the effects of DMOG on the proliferation and differentiation of spermatogonial stem cells (SSCs) in Bama minipigs. Methods: Gradient concentrations of DMOG were added into the culture medium, HIF-1α protein in SSCs was detected by western blot analysis, the relative transcription levels of the SSC-specific genes were analyzed using quantitative reverse transcription polymerase chain reaction (qRT-PCR). Six days post-induction, the genes related to spermatogenesis were detected by qRT-PCR, and the DNA content was determined by flow cytometry. Results: Results revealed that the levels of HIF-1α protein increased in SSCs with the DMOG treatment in a dose-dependent manner. The relative transcription levels of SSC-specific genes were significantly upregulated (p < 0.05) by activating HIF-1α expression. The induction results showed that DMOG significantly increased (p < 0.05) the spermatogenesis capability of SSCs, and the populations of haploid cells significantly increased (p < 0.05) in DMOG-treated SSCs when compared to those in DMOG-untreated SSCs. Conclusion: We demonstrate that DMOG can promote the spermatogenesis activity of SSCs.
Wang Xianyao,Wang Huizhen,Lu Junhou,Feng Zhanhui,Liu Zhongshan,Song Hailiang,Wang Heng,Zhou Yanhua,Xu Jianwei 한국조직공학과 재생의학회 2020 조직공학과 재생의학 Vol.17 No.5
BACKGROUND: Mesenchymal stem cell (MSC)-based cell transplantation is an effective means of treating chronic liver injury, fibrosis and end-stage liver disease. However, extensive studies have found that only a small number of transplanted cells migrate to the site of injury or lesion, and repair efficacy is very limited. METHODS: Bone marrow-derived MSCs (BM-MSCs) were generated that overexpressed the erythropoietin (EPO) gene using a lentivirus. Cell Counting Kit-8 was used to detect the viability of BM-MSCs after overexpressing EPO. Cell migration and apoptosis were verified using Boyden chamber and flow cytometry, respectively. Finally, the anti-fibrosis efficacy of EPO-MSCs was evaluated in vivo using immunohistochemical analysis. RESULTS: EPO overexpression promoted cell viability and migration of BM-MSCs without inducing apoptosis, and EPO-MSC treatment significantly alleviated liver fibrosis in a carbon tetrachloride (CCl4) induced mouse liver fibrosis model. CONCLUSION: EPO-MSCs enhance anti-fibrotic efficacy, with higher cell viability and stronger migration ability compared with treatment with BM-MSCs only. These findings support improving the efficiency of MSCs transplantation as a potential therapeutic strategy for liver fibrosis.
The development and review of Spatial data index technology
Shuhua Ren,Huimin Meng,Huizhen Yan 한국멀티미디어학회 2006 한국멀티미디어학회 국제학술대회 Vol.2006 No.-
The research in spatial data processing mainly focus on two or multi-dimension data processing, and spatiotemporal data processing on moving objects are now more highlight. Spatial data structure are complicated, so the operations on spatial data will spend more cost. Therefore the optimization on spatial query is the key-point in application, and spatial index structures become the bottle-neck in spatial application, many scholars have done their best and given many methods on the problems. The paper present the review on the development of spatial index methods in recently years, and give a perspective in the spatial index and spatiotemporal index technology.
A Compensated Software Reliability Model Based on Unascertained Rational Number
Yongqiang Zhang,Wen Chen,Huizhen Yan 한국멀티미디어학회 2006 한국멀티미디어학회 국제학술대회 Vol.2006 No.-
The software reliability model based on unascertained ration number has unique superiority. It does not have any assumption about software fault process. Moreover, its algorithm is simple, and it avoids derivation of nonlinear equations set. But the characteristic of the algorithm itself determines that the estimation of this model is the pessimistic estimation. In this view, this paper makes some improvement to this model, and puts forward the compensated software reliability model based on unascertained rational number, which make the model have wider applicability and suit the reliability growth feature better.