Nonlinear Predictive Control of Active Four-wheel Steering Vehicles

Shuyou Yu,Wenbo Li,Baojun Lin,Yongfu Li,Hong Chen,Hongqing Chu,Jianhua Yu 제어·로봇·시스템학회 2023 International Journal of Control, Automation, and Vol.21 No.10

In order to improve the handling stability of active four-wheel steering vehicles, a nonlinear model predictive controller is presented, which can guarantee that the actual sideslip angle and yaw rate can track the ideal sideslip angle and the ideal yaw rate through control of the front and rear wheel angles. A nonlinear static tyre model connected with a linear dynamic model is adopted to describe the vehicle dynamics. Furthermore, the tyre model is replaced by a map in the optimization problem of nonlinear model predictive control. The introduction of maps can reduce the online computational time by a trade-off between the computational burden of CPU and the storage burden of ROM. Simulation results in CarSim indicate that the proposed controller can follow the outputs of the ideal reference model, reduce the computational burden, and improve the handling stability of the active four-wheel steering vehicles effectively.

Mechanical and Thermal Properties of Epoxy Resins Modified by a Novel Thermoplastic-polyimide

Yu Ji,Yan Zhang,Ping Wang,Yuanyuan Li,Jianhua Sui 한국섬유공학회 2021 Fibers and polymers Vol.22 No.1

In this paper, a novel polyimide with trifluoromethyl group (PIS) was synthesized successfully and used toimprove the toughness of epoxy resins. Five modified epoxy resins (5, 7.5, 10, 12.5 and 15 wt%) were prepared andinvestigated, respectively. The structure, thermal properties, tensile properties, viscoelastic properties, toughness andmorphology of modified epoxy resins were studied by Fourier Transform Infrared Spectroscopy (FT-IR), thermogravimetricanalysis (TGA), Instron 5967, Dynamic Mechanical Analysis (DMA), and Scanning Electron Microscopy (SEM). Theresults showed that the epoxy resins modified with PIS exhibited good thermal stability which the glass transitiontemperatures increased from 135.9 oC to 146.4 oC. Tensile strength of modified epoxy resins increased from 40.4 MPa to92.3 MPa. The KIC values increased from 0.86 MPa·m1/2 to 1.56 MPa·m1/2 indicated that the toughness enhancement wasmarkedly. The fracture modes also were examined by SEM images and exhibited the fracture mode changed from the brittleone to ductile fracture with varied weight of the novel trifluoromethyl-polyimide.

GROWTH AND MICROSTRUCTURES OF ULTRATHIN Bi 2 Te 3 NANOPLATES BY MODIFIED HOT WALL EPITAXY

JIANHUA GUO,HUIYONG DENG,YUCONG LIU,GUJIN HU,XIAONAN LI,GUOLIN YU,NING DAI 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2014 NANO Vol.9 No.6

Ultrathin Bi 2 Te 3 nanoplates have been grown on an oxidized silicon substrate by a modi¯ed hotwall epitaxy (HWE) method, in which a quartz plate with holes was employed. The micro-structures and optical properties of Bi 2 Te 3 nanoplates were investigated by X-ray di®raction(XRD), scanning electron microscopy (SEM), atomic force microscope (AFM) and micro-Ramanspectroscopy. The results show that ultrathin Bi 2 Te 3 nanoplates with the thickness of about sixquintuple layers (QLs) are obtained, which is di±cult for the traditional HWE technique. TheRaman vibration mode A11gfrom the nanoplates exhibits an obviously red shift with decreasingthickness. The thickness variation of one nanoplate was obtained by the Raman map derivedfrom the vibration frequency of A11gmode and is in good agreement with the AFM result, whichindicates that Raman map is an e®ective method to characterize the thickness di®erence ofultrathin Bi 2 Te 3 nanoplates.

Experimental Investigation of the Hydraulic Performance of a Hydraulic-Jump-Stepped Spillway

Yu Zhou,Jianhua Wu,Fei Ma,Shangtuo Qian 대한토목학회 2021 KSCE Journal of Civil Engineering Vol.25 No.10

For a traditional stepped spillway, low energy dissipation and cavitation damage may occur when the unit discharge is larger than a limit due to reduced air entrainment in the flow. In the present work, a new type of stepped spillway called hydraulic-jump-stepped spillway (HJSS) was developed, and the air was efficiently entrained into the flow by means of a hydraulic jump in the aeration basin, which was an aeration element of this stepped spillway. Compared with the traditional stepped spillway, various aspects of the hydraulic performance of the HJSS were experimentally investigated, including the flow pattern, energy dissipation, air entrainment characteristics and time-averaged pressure. Physical model results demonstrated that the HJSS achieved a higher energy dissipation, a more favorable air entrainment performance, and a more reasonable pressure distribution. The HJSS successfully increased the unit discharge from 50 – 60 m2/s for a traditional stepped spillway to 101.47 m2/s.

Cavitation–silt erosion in sand suspensions

Yu Wang,Jianhua Wu,Fei Ma 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.12

Cavitation–silt erosion in sand suspensions has elicited research attention. However, erosion characteristics in various conditions of liquids remain unknown due to their complex mechanisms. Thus, the effects of sand size, concentration, and temperature of sand suspensions on cavitation–silt erosion and viscosity were experimentally investigated in the present work. The findings proved the existence of critical sand size. The silt–cavitation erosion decreased with the increase of sand concentration when the sand was smaller than the critical size, and it increased with the increment of the sand size and temperature. A good relationship between the viscosity and the sand size, concentration, and temperature was determined. Moreover, the cavitation–silt erosion mechanisms were obtained on the basis of the viscosity and impingement erosion analysis standpoint.

Association between Delayed Lactogenesis II and Early Milk Volume among Mothers of Preterm Infants

Xiurong Yu,Jianhua Li,Xiangyun Lin,Dandan Luan 한국간호과학회 2019 Asian Nursing Research Vol.13 No.2

Purpose: This study aimed to evaluate the effect of delayed lactogenesis Ⅱ on early milk volume in mothers expressing milk for their preterm infants. Methods: 142 mothers with preterm infants participated in a longitudinal cohort study, the milk volumes over 14 days postpartum between mothers with delayed lactogenesis Ⅱ ( 72 hours) and mothers with non-delayed lactogenesis Ⅱ(< 72 hours) were compared using Wilcoxon's rank sum tests. Results: The prevalence of delayed lactogenesisⅡ among mothers of preterm infants was 36.0% (36/100). There existed negative correlations between the onset of lactogenesis Ⅱ and the daily milk volumes( rs ¼ 0.525~0.354, p ¼ .002 ~ p < .001). The milk volumes in every 24-hour of the 14 days postpartum in delayed group were significantly less than that in non-delayed group (p ¼ .002 ~ p < .001). After controlling for the covariates, pregnancy-induced hypertension syndrome, delayed expression initiation, shorter daily sleeping time were found to be the risk factors for delayed lactogenesis Ⅱ. Conclusion: Delayed lactogenesis Ⅱ was associated with lower milk volume in early postpartum period. Women who were at risk for delayed lactogenesis Ⅱ need targeted interventions and additional support during pregnancy and postpartum.

Research Progress of Hydrostatic Bearing and Hydrostatic-Hydrodynamic Hybrid Bearing in High-End Computer Numerical Control Machine Equipment

Xiaodong Yu,Weicheng Gao,Yanan Feng,Guangqiang Shi,Shihao Li,Minmin Chen,Ruiming Zhang,Junfeng Wang,Wentao Jia,Jianhua Jiao,Ruichun Dai 한국정밀공학회 2023 International Journal of Precision Engineering and Vol.24 No.6

Hydrostatic bearing has the advantages of wide speed range, large bearing capacity, high precision and stability. Hydrostatic-hydrodynamic hybrid bearing can make up for the lack of stiffness of hydrostatic bearing and prevent tribological failure under the condition of high speed and heavy load. Therefore, hydrostatic bearing and hydrostatic-hydrodynamic hybrid bearing have become important bearing parts of high-end computer numerical control (CNC) machine equipment. The research on hydrostatic and hydrostatic-hydrodynamic open a new way for precision improvement of high-end CNC machine equipment. This paper reviews research progress of hydrostatic linear guideway, hydrostatic rest and ram, hydrostatic thrust bearing, hydrostatic-hydrodynamic thrust bearing and hydrostatic-hydrodynamic spindle of high-end CNC machine equipment, and discusses the influence of structure and working parameters on lubrication performance, accuracy and stability of bearing parts. Finally, the future research direction in hydrostatic bearing and hydrostatic-hydrodynamic hybrid bearing are suggested. This review provides a theoretical basis for design and development of high-end CNC machine equipment in the future.

Identification and Validation of Circulating MicroRNA Signatures for Breast Cancer Early Detection Based on Large Scale Tissue-Derived Data

Xiaokang Yu,Jinsheng Liang,Jiarui Xu,Xingsong Li,Shan Xing,Huilan Liu,Wan-Li Liu,Dongdong Liu,Jianhua Xu,Lizhen Huang,Hongli Du 한국유방암학회 2018 Journal of breast cancer Vol.21 No.4

Purpose: Breast cancer is the most commonly occurring cancer among women worldwide, and therefore, improved approaches for its early detection are urgently needed. As microRNAs (miRNAs) are increasingly recognized as critical regulators in tumorigenesis and possess excellent stability in plasma, this study focused on using miRNAs to develop a method for identifying noninvasive biomarkers. Methods: To discover critical candidates, differential expression analysis was performed on tissue-originated miRNA profiles of 409 early breast cancer patients and 87 healthy controls from The Cancer Genome Atlas database. We selected candidates from the differentially expressed miRNAs and then evaluated every possible molecular signature formed by the candidates. The best signature was validated in independent serum samples from 113 early breast cancer patients and 47 healthy controls using reverse transcription quantitative real-time polymerase chain reaction. Results: The miRNA candidates in our method were revealed to be associated with breast cancer according to previous studies and showed potential as useful biomarkers. When validated in independent serum samples, the area under curve of the final miRNA signature (miR-21-3p, miR-21-5p, and miR-99a-5p) was 0.895. Diagnostic sensitivity and specificity were 97.9% and 73.5%, respectively. Conclusion: The present study established a novel and effective method to identify biomarkers for early breast cancer. And the method, is also suitable for other cancer types. Furthermore, a combination of three miRNAs was identified as a prospective biomarker for breast cancer early detection.

Numerical analysis of thermal dynamics and mixing performance in the blade-type static mixers

Yanfang Yu,Yaxin Chen,Huibo Meng,Yunjuan Yao,Dongzhou Liu,Jianhua Wu 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.7

The turbulent thermal dynamics and mixing performance of kenics static mixer (KSM), lightnin static mixer (LSM) and Q-type static mixer (QSM) were numerically simulated with uniform heat flux within the range of Reynolds numbers (Re) between 6000 and 30000. The numerical predictions of Nusselt number (Nu) and friction coefficient (f) in KSM were well consistent with the experimental data. The dean vortices, thermal resistance, entropy generation and field synergy were fully analyzed to obtain the enhancement mechanism of heat transfer performance. The synergy performance between temperature gradient and flow field firstly decreased and then increased and are superior to that of KSM with increasing Re. With the same Re, the entropy generation rates of LSM are 0.93-0.94 times that of QSM. LSM is a better alternative consideration for convection mixing and heat transfer enhancement. Two new relationships between Nu and f under different dimensionless uniform heat flux are obtained.

Parallel Execution of Data-intensive Web Services Based on Data-flow Constructs and I/O Operation Ratio

Dongjin Yu,Qi Zhu,Jianhua Shao,Chang Li,Youwei Yuan,Wanqing Li 보안공학연구지원센터 2014 International Journal of Database Theory and Appli Vol.7 No.4