Spatial Path Following Control of an Autonomous Underactuated Airship

Wei-Xiang Zhou,Chang Xiao,Ping-Fang Zhou,Deng-Ping Duan 제어·로봇·시스템학회 2019 International Journal of Control, Automation, and Vol.17 No.7

This paper studies the spatial path following control of an autonomous underactuated airship in the presence of model uncertainties and external disturbances. Firstly, the nonlinear dynamics model, kinematics modeland path following error dynamics model are given. And the control objective is formulated. Then, an adaptivebackstepping sliding mode controller is designed. Besides, to overcome the disadvantage of dependence on theaccurate vehicle model, a nonlinear disturbance observer (NDOB) is adopted to estimate the attack and sideslip angular velocities. In addition, when backstepping technique is uesd, the complex analytic computation of commandderivative is required to be known. To handle this problem, a sliding mode differentiator is implemented to generatethe command derivatives. Finally, the closed loop stability for the system is proved using Lyapunov stability theory. Numerical simulations are given to demonstrate the effectiveness of the proposed method.

Lymph Node Ratio is an Independent Prognostic Factor in Node Positive Rectal Cancer Patients Treated with Preoperative Chemoradiotherapy Followed by Curative Resection

Zeng, Wei-Gen,Zhou, Zhi-Xiang,Wang, Zheng,Liang, Jian-Wei,Hou, Hui-Rong,Zhou, Hai-Tao,Zhang, Xing-Mao,Hu, Jun-Jie Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.13

Background: The lymph node ratio (LNR) has been shown to be an important prognostic factor for colorectal cancer. However, studies focusing on the prognostic impact of LNR in rectal cancer patients who received neoadjuvant chemoradiotherapy (CRT) followed by curative resection have been limited. The aim of this study was to investigate LNR in rectal cancer patients who received neoadjuvant chemoradiotherapy (CRT) followed by curative resection. Materials and Methods: A total of 131 consecutive rectal cancer patients who underwent neoadjuvant CRT and total mesorectal excision were included in this study. Patients were divided into two groups according to the LNR (${\leq}0.2$ [n=86], >0.2 [n=45]) to evaluate the prognostic effect on overall survival (OS) and disease-free survival (DFS). Results: The median number of retrieved and metastatic lymph node (LN) was 14 (range 1-48) and 2 (range 1-10), respectively. The median LNR was 0.154 (range 0.04-1.0). In multivariate analysis, LNR was shown to be an independent prognostic factor for both overall survival (hazard ratio[HR]=3.778; 95% confidence interval [CI] 1.741-8.198; p=0.001) and disease-free survival (HR=3.637; 95%CI 1.838-7.195; p<0.001). Increased LNR was significantly associated with worse OS and DFS in patients with <12 harvested LNs, and as well as in those ${\geq}12$ harvested LNs (p<0.05). In addition, LNR had a prognostic impact on both OS and DFS in patients with N1 staging (p<0.001). Conclusions: LNR is an independent prognostic factor in ypN-positive rectal cancer patients, both in patients with <12 harvested LNs, and as well as in those ${\geq}12$ harvested LNs. LNR provides better prognostic value than pN staging. Therefore, it should be used as an additional prognostic indicator in ypN-positive rectal cancer patients.

Space Charge Behavior of Oil-paper Insulation Thermally Aged under Different Temperatures and Moistures

Zhou, Yuan-Xiang,Huang, Meng,Chen, Wei-Jiang,Jin, Fu-Bao The Korean Institute of Electrical Engineers 2015 Journal of Electrical Engineering & Technology Vol.10 No.3

Moisture and high temperature are the most important factors that lead to the ageing of oil-paper insulation, but the research about space charge characteristics of oil-paper insulation does not take the combined effect of ambient temperature, moisture and thermal ageing into account. The pulsed electroacoustic (PEA) method was used to investigate the influence of moisture and temperature on space charge characteristics of oil paper at different ageing stages. The results showed that moisture could speed up formation of space charge in oil paper when water concentration was low, but the formation was restrained if the water concentration was high. At the beginning of thermal ageing, heterogeneous charge accumulation had predominance, but it gradually changed to homogeneous charge injection with ageing. It was believed that moisture concentration could speed up ageing and enhance charge accumulation on one hand, and accelerate or slow down the establishment speed of space charge on the other hand, therefore, charge accumulation type changed with ageing. The more seriously the oil-paper insulation was thermally aged, the deeper the trap energy level was, hence more space charge was trapped, which could be speeded up by increasing the ageing temperature, but the effect of ambient temperature did not fit the Arrhenius law.

Temperature Response to Tensile Characteristics of the Hot Asphalt Mixtures

Wei Si,Ning Li,Biao Ma,Yu-xiang Tian,Xue-yan Zhou 대한토목학회 2016 KSCE JOURNAL OF CIVIL ENGINEERING Vol.20 No.4

Asphalt concrete is one type of the temperature sensitive mixtures, which is the most and broadest used pavement material in the world. Asphalt pavement suffers from the impact of temperature due to the temperature variation in different districts and environments. Facing temperature sensitivity, this paper uses Indirect Tensile Test (IDT) to analyze the tensile characters of asphalt mixture under different temperatures (-20°C, -10°C, 0°C, 15°C, 20°C, 45°C, and 60°C). The influence factors of temperature, loading rate, asphalt content, asphalt types, and mixtures gradation are evaluated. Piecewise linear model, logarithm linear model and S-logistic nonlinear model are applied to simulate the variation of flexural tensile characters with temperature change. Results show that temperature has significant influence on flexural tensile properties. Loading rates also has obvious influence on flexural tensile characteristics. With temperature changes, asphalt types have evident influence on mixture’s tensile characteristics, SBR modified asphalt has better performance at the lower temperature environment. Mixtures’ gradation has important effect on tensile strength and tensile strain as well, while due the similarity between two gradations, it is hard to precisely recommend which one is better. Asphalt content has evident influence on mixtures properties at the same temperature condition. Research results provide suggestions and applications for construction and performance of asphalt pavement. The results also indicate that IDT would be a practical option to evaluate the properties of asphalt mixture in all temperature ranges.

New Method for Analysis of Sliding Cable Structures in Bridge Engineering

Xiang-min Yu,De-wei Chen,Zhi-zhou Bai 대한토목학회 2018 KSCE Journal of Civil Engineering Vol.22 No.11

The Sliding Cable Structure (SCS) is widely used in bridge construction by cable crane method. The SCS generally consists of cables and fixed pulleys and the cables will slide around the pulleys when the cables are loaded until the balanced state is achieved. In this paper, an efficient Angle Bisector Method (ABM) is proposed for the mechanical analysis of SCS. The constraint effect of pulley on the cable is simulated by fixed hinge and the constraint force perpendicular to the angle bisector of cable elements adjacent to the pulley is therefore zero at balanced state. By utilizing “Unit Length Influence Matrix” (ULIM), the adjustment of unstressed length of each sub-cable can be determined. As the angle bisector at each pulley will change when the unstressed lengths of cables are changed, iterative procedures are necessary to find the convergence solutions. The proposed method is firstly verified by two examples and then applied to the analysis of cable crane during construction of the world’s longest steel truss cable-stayed bridge, namely Yachihe Bridge. Satisfactory numerical solutions can be obtained only with several iterations and are in good agreement with field measurements from the cable crane load tests, which confirms the accuracy and validity of the proposed method.

Clinical Observation of Three Dimensional Conformal Radiotherapy with Tamoxifen in Treatment of Postoperative Malignant Glioma

Zhou, Shao-Bing,Liu, Yang-Chen,Yin, Xiao-Xiang,Ding, Wen-Xiu,Guo, Xin-Wei,Gu, Liang,Huang, Xin-En Asian Pacific Journal of Cancer Prevention 2015 Asian Pacific journal of cancer prevention Vol.16 No.5

Objective: To evaluate the efficacy and adverse effects of three dimensional conformal radiotherapy (3D-CRT) with tamoxifen in treating patients with postoperative malignant glioma. Patients and Methods: 60 patients of postoperative malignant glioma were randomly assigned into two groups, 30 patients were treated with 3D-CRT plus tamoxifen (treatment group), and the other 30 patients with 3D-CRT plus temozolomide (control group). All patients were radiated by 6MV X-ray, 2.0Gy per fraction, once daily, with a total dose (DT) of 56~60Gy. Tamoxifen was delivered at $60mg/m^2/d$, temozolomide was given at $75mg/m^2/d$. All patients were treated with concurrent radiotherapy. Results: One, 2, 3 year survival rates of treatment and control group were 63.3%, 30.0%, 23.0% and 70.0%, 33.3%, 26.7%, respectively (${\chi}^2=0.01$, 0.23, 0.09, P>0.05). The rate of thromboembolism in treatment group was 6.7%. Conclusion: Therapeutic efficacy of two groups was similar, but it was more cost-effective in treatment group, and toxicity did not increase.

A Stability Study of the Longest Steel Truss Deck Cable-stayed Bridge during Construction

Xiang-min Yu,De-wei Chen,Zhi-zhou Bai 대한토목학회 2019 KSCE Journal of Civil Engineering Vol.23 No.4

For long-span cable-stayed bridges, the stability performance during construction is vital from the point view of structural safety. This paper presents an extensive study of stability performance during construction for the world longest steel truss deck cable-stayed bridge-Yachihe Bridge. Based on the finite element analysis, the Linear Elastic Stability (LES), Nonlinear Elastic Stability (NLES) and Nonlinear Inelastic Stability (NLIES) of the bridge have been investigated to identify the effects of geometry nonlinearity and material nonlinearity on the structural stability performance. In addition, the influences of temperature variations and static lateral winds on stability performance are also focused. The results show that: 1) Under design ambient temperature, the corresponding design of steel truss deck yields the minimum stability coefficients of LES, NLES and NLIES by 5.72, 4.64 and 2.96, respectively, corresponding to the completion of superimposed dead loads; 2) both the geometry nonlinearity and material nonlinearity have been identified to make negative effects on the stability performance and the material nonlinearity will reduce the structural stabilitycoefficient largely; 3) during construction, the rise and drop in temperature will increase and decrease the stability coefficients, respectively. NLIES is the most sensitive one to variations of temperature; and 4) the lateral static winds slightly reduce the stability coefficients of LES, NLES and NLIES.

Interface engineering for improving reliability of resistance switching in Cu/HfO₂/TiO₂/Pt structure

Wei Zhou, Li,Long Shao, Xing,Yuan Li, Xiang,Jiang, Hao,Chen, Ran,Jean Yoon, Kyung,Jin Kim, Hae,Zhang, Kailiang,Zhao, Jinshi,Seong Hwang, Cheol American Institute of Physics 2015 APPLIED PHYSICS LETTERS Vol.107 No.7

Development, Validation and Comparison of Artificial Neural Network and Logistic Regression Models Predicting Eosinophilic Chronic Rhinosinusitis With Nasal Polyps

Zhou Huiqin,Fan Wenjun,Qin Danxue,Liu Peiqiang,Gao Ziang,Lv Hao,Zhang Wei,Xiang Rong,Xu Yu 대한천식알레르기학회 2023 Allergy, Asthma & Immunology Research Vol.15 No.1

Purpose: Chronic rhinosinusitis with nasal polyps (CRSwNP) can be classified into eosinophilic CRSwNP (eCRSwNP) and non-eosinophilic CRSwNP (non-eCRSwNP) by tissue biopsy, which is difficult to perform preoperatively. Clinical biomarkers have predictive value for the classification of CRSwNP. We aimed to evaluate the application of artificial neural network (ANN) modeling in distinguishing different endotypes of CRSwNP based on clinical biomarkers. Methods: Clinical parameters were collected from 109 CRSwNP patients, and their predictive ability was analyzed. ANN and logistic regression (LR) models were developed in the training group (72 patients) and further tested in the test group (37 patients). The output variable was the diagnosis of eCRSwNP, defined as tissue eosinophil count > 10 per high-power field. The receiver operating characteristics curve was used to assess model performance. Results: A total of 15 clinical features from 60 healthy controls, 60 eCRSwNP and 49 non-eCRSwNP were selected as candidate predictors. Nasal nitric oxide levels, peripheral eosinophil absolute count, total immunoglobulin E, and ratio of bilateral computed tomography scores for the ethmoid sinus and maxillary sinus were identified as important features for modeling. Two ANN models based on 4 and 15 clinical features were developed to predict eCRSwNP, which showed better performance, with the area under the receiver operator characteristics significantly higher than those from the respective LR models (0.976 vs. 0.902, P = 0.048; 0.970 vs. 0.845, P = 0.011). All ANN models had better fits than single variable prediction models (all P < 0.05), and ANN model 1 had the best predictive performance among all models. Conclusions: Machine learning models assist clinicians in predicting endotypes of nasal polyps before invasive detection. The ANN model has the potential to predict eCRSwNP with high sensitivity and specificity, and is superior to the LR model. ANNs are valuable for optimizing personalized patient management.

Mechanism analysis of pressure fluctuation in wheel loader articulated steering hydraulic system

Bing-wei Cao,Xinhui Liu,Wei Chen,Chen Zhou,Fei-xiang Xu 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.10

This paper studies the influence of hinge point positioning of a steering cylinder on the pressure fluctuation of the steering system of a wheel loader. Affected by the hinge point position of the steering cylinder, the main causes of the pressure fluctuation are found to be the stroke difference and the force arm difference. Based on theoretical analysis, the hinge point positioning of the steering cylinder was optimized by using genetic algorithm (GA). The AMEsim simulation model of the steering system was built to verify the accuracy of the GA. The wheel loader was reformed according to the optimized articulated points position. Steering tests showed a significant drop in system pressure fluctuation, the energy consumed is also reduced. Further, the analysis shows that the force arm difference is the main factor causing the pressure fluctuation, providing the theoretical and experimental basis for the design of a steering system of wheel loaders.