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.

Production of Dimethylsulfide and Dimethyisulfoniopropionate by Phytoplankton in the Water of Jiaozhou Bay

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.

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.

Position and speed estimation for high speed permanent magnet synchronous motors using wideband synchronous fundamental‑frequency extraction filters

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.

Parametric study of an undulating plate in a power-extraction regim

Xiaojing Sun,Jihua Zhang,Huizhen Li,Diangui Huang 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.1

Our previous studies suggest that instead of propulsion, a body undergoing lateral traveling-wave-like motions can also work like a kinetic energy harvester which extracts energy from moving fluids including wind and water currents. Parameters including wavelength, dimensionless wave velocity and amplitude have critical effects on the energy extraction efficiencies of this type of undulating foil energy harvester. In this paper, a two-dimensional, numerical simulation of a flexible plate undergoing a traveling wave motion was then conducted. At a given dimensionless wave speed, it is found that there exits an optimum wavelength at which this type of energy harvester can extract the maximum amount of kinematic energy from the flow. Moreover, the optimum value of the wavelength increases as amplitude increases. A high efficiency area appears under the optimal combination of wavelength and amplitude. At a given amplitude, the optimal dimensionless wave speed for maximum power extraction decreases with increasing wavelength. The high efficiency area of the undulating plate resulting from the optimal combination of wavelength and wave speed is identified. At a given wave length, there is an optimal value of amplitude at which the maximum energy extraction can be achieved. In this case, a high efficiency area representing the optimal combination of amplitude and wave speed has also been discovered.

Contrast-Enhanced Harmonic Ultrasonography for the Assessment of Prostate Cancer Aggressiveness: a Preliminary Study

Yunkai Zhu,Yaqing Chen,Jun Jiang,Ren Wang,Yongchang Zhou,Huizhen Zhang 대한영상의학회 2010 Korean Journal of Radiology Vol.11 No.1

Objective: To determine whether contrast-enhanced harmonic ultrasonography can be used to predict the aggressiveness of prostate cancer. Materials and Methods: Contrast-enhanced harmonic ultrasonography was performed in 103 patients suspected of prostate cancer before biopsy. Time intensity curves were reconstructed for systematic biopsy sites and sonographic abnormalities. The characteristics of the curves were described using hemodynamic indices including arrival time (AT), time-to-peak (TTP), and peak intensity (PI). The differences of hemodynamic indices between high-grade and low-grade cancer were analyzed and the correlations between the hemodynamic indices and biopsy Gleason score were studied. Results: Prostate cancer was detected in 41 of 103 patients and there were significant differences in the hemodynamic indices between the biopsy sites of the non-malignant patients and prostate cancer lesions (p < 0.05). The prostate biopsies revealed 154 prostate cancer lesions, including 31 low-grade lesions and 123 high-grade lesions. The hemodynamic indices AT and TTP of highgrade tumors were significantly shorter than those of low-grade tumors (p = 0.001, 0.002). In addition, high-grade peripheral zone (PZ) tumors had higher PI than low-grade PZ tumors (p = 0.009). The PZ prostate cancer Gleason score correlated with PI, AT and TTP, with Spearman correlation coefficients of 0.223, -0.335, and -0.351, respectively (p = 0.013, < 0.001 and < 0.001). Conclusion: Contrast-enhanced ultrasound measurements of hemodynamic indices correlate with the prostate cancer Gleason score. Objective: To determine whether contrast-enhanced harmonic ultrasonography can be used to predict the aggressiveness of prostate cancer. Materials and Methods: Contrast-enhanced harmonic ultrasonography was performed in 103 patients suspected of prostate cancer before biopsy. Time intensity curves were reconstructed for systematic biopsy sites and sonographic abnormalities. The characteristics of the curves were described using hemodynamic indices including arrival time (AT), time-to-peak (TTP), and peak intensity (PI). The differences of hemodynamic indices between high-grade and low-grade cancer were analyzed and the correlations between the hemodynamic indices and biopsy Gleason score were studied. Results: Prostate cancer was detected in 41 of 103 patients and there were significant differences in the hemodynamic indices between the biopsy sites of the non-malignant patients and prostate cancer lesions (p < 0.05). The prostate biopsies revealed 154 prostate cancer lesions, including 31 low-grade lesions and 123 high-grade lesions. The hemodynamic indices AT and TTP of highgrade tumors were significantly shorter than those of low-grade tumors (p = 0.001, 0.002). In addition, high-grade peripheral zone (PZ) tumors had higher PI than low-grade PZ tumors (p = 0.009). The PZ prostate cancer Gleason score correlated with PI, AT and TTP, with Spearman correlation coefficients of 0.223, -0.335, and -0.351, respectively (p = 0.013, < 0.001 and < 0.001). Conclusion: Contrast-enhanced ultrasound measurements of hemodynamic indices correlate with the prostate cancer Gleason score.

Monitoring Response to Neoadjuvant Chemotherapy of Primary Osteosarcoma Using Diffusion Kurtosis Magnetic Resonance Imaging: Initial Findings

Chenglei Liu,Yan Xi,Mei Li,Qiong Jiao,Huizhen Zhang,Qingcheng Yang,Weiwu Yao 대한영상의학회 2019 Korean Journal of Radiology Vol.20 No.5

Objective: To determine whether diffusion kurtosis imaging (DKI) is effective in monitoring tumor response to neoadjuvant chemotherapy in patients with osteosarcoma. Materials and Methods: Twenty-nine osteosarcoma patients (20 men and 9 women; mean age, 17.6 ± 7.8 years) who had undergone magnetic resonance imaging (MRI) and DKI before and after neoadjuvant chemotherapy were included. Tumor volume, apparent diffusion coefficient (ADC), mean diffusivity (MD), mean kurtosis (MK), and change ratio (ΔX) between preand post-treatment were calculated. Based on histologic response, the patients were divided into those with good response (≥ 90% necrosis, n = 12) and those with poor response (< 90% necrosis, n = 17). Several MRI parameters between the groups were compared using Student’s t test. The correlation between image indexes and tumor necrosis was determined using Pearson’s correlation, and diagnostic performance was compared using receiver operating characteristic curves. Results: In good responders, MDpost, ADCpost, and MKpost values were significantly higher than in poor responders (p < 0.001, p < 0.001, and p = 0.042, respectively). The ΔMD and ΔADC were also significantly higher in good responders than in poor responders (p < 0.001 and p = 0.01, respectively). However, no significant difference was observed in ΔMK (p = 0.092). MDpost and ΔMD showed high correlations with tumor necrosis rate (r = 0.669 and r = 0.622, respectively), and MDpost had higher diagnostic performance than ADCpost (p = 0.037) and MKpost (p = 0.011). Similarly, ΔMD also showed higher diagnostic performance than ΔADC (p = 0.033) and ΔMK (p = 0.037). Conclusion: MD is a promising biomarker for monitoring tumor response to preoperative chemotherapy in patients with osteosarcoma.

3-Methylthiopropionic Acid of Rhizoctonia solani AG-3 and Its Role in the Pathogenicity of the Fungus

Frederick Kankam,Hai-Tao Long,Jing-He,Chun-hong Zhang,Hui-Xiu Zhang,Lumei Pu,Huizhen Qiu 한국식물병리학회 2016 Plant Pathology Journal Vol.32 No.2

Studies were conducted to determine the role of 3-methylthioproprionicacid (MTPA) in the pathogenicityof potato stem canker, Rhizoctonia solani, and theconcentrations required to inhibit growth of R. solaniunder laboratory and plant house-based conditions. The experiments were laid out in a completely randomizeddesign with five treatments and five replications. The treatments were 0, 1, 2, 4, and 8 mM concentrationsof MTPA. The purified toxin exhibited maximalactivity at pH 2.5 and 30oC. MTPA at 1, 2, 4, and 8 mMlevels reduced plant height, chlorophyll content, haulmfresh weight, number of stolons, canopy development,and tuber weight of potato plants, as compared to thecontrol. MTPA significantly affected mycelial growthwith 8 mM causing the highest infection. The potatoseedlings treated with MTPA concentrations of 1.0–8.0mM induced necrosis of up to 80% of root system area. Cankers were resulted from the injection of potatoseedling stems with 8.0 mM MTPA. The results showedthe disappearance of cell membrane, rough mitochondrialand cell walls, change of the shape of chloroplasts,and swollen endoplasmic reticulum. Seventy-six (76)hours after toxin treatment, cell contents were completelybroken, cytoplasm dissolved, and more chromatinwere seen in the nucleus. The results suggestedthat high levels of the toxin concentration caused cellmembrane and cytoplasm fracture. The integrity of cellularstructure was destroyed by the phytotoxin. Theconcentrations of the phytotoxin were significantly correlatedwith pathogenicity and caused damage to thecell membrane of potato stem base tissue.