Parameter Identification for a Quadrotor Helicopter Using Multivariable Extremum Seeking Algorithm

Weizhen Liu,Xin Huo,Jinkun Liu,Libin Wang 제어·로봇·시스템학회 2018 International Journal of Control, Automation, and Vol.16 No.4

Parameter identification for a quadrotor helicopter is challenging from a theoretical point of view. In this paper, a closed-loop multivariable extremum seeking algorithm (MESA) is proposed for a nonlinear quadrotor helicopter parameter identification with two groups of input data. The proposed scheme is universally applicable to the closed-loop identification for cross-coupling multivariable processes where the identification problem is formulated as a minimization of a cost function. As the gradients of the performance parameters are obtained by step response experiments, the whole system searches along the negative gradient of the cost function until the reference trajectory or point is derived. Since the cost function is treated as a mapping from the model parameters, then the parameters can be identified online and in a real-time manner. The procedure of the identification algorithm is presented, and its effectiveness is illustrated by numerical simulations.

Reinforcement Analysis of Rigid Hangers for Existing Old Arch Bridges: A Case Study of Ling Bridge

Shuai Yuan,Weizhen Chen,Fan Yang,Tiantao He,Guoxian Liu 한국강구조학회 2019 International Journal of Steel Structures Vol.19 No.6

Ling Bridge, built in 1936, is an old half-through riveted steel arch bridge with rigid hangers and a fl oating deck system. The eff ects of various factors, such as temperature, vehicle load, and crowd load, have caused large additional stresses on the rigid hangers. According to the inspection in 2011, the bridge was in a dangerous state. Therefore, improving the structural strength of the bridge and prolonging the service life for another 40 years while protecting the cultural relic were major problems. This study analyzes rigid hangers on the premise that the reinforcement schemes of other bridge components have been determined. First, the damage situation, material properties and mechanical behaviors of old hangers are evaluated. Second, an appropriate reinforcement method is proposed. Third, mechanical and fatigue analyses are conducted on the new structures to prove the rationality of the reinforcement method. For the undemolished old structures, a fracture assessment of existing damage is performed to obtain the evolution laws and ensure safety. Finite element calculations and fatigue fracture analyses show that the proposed reinforcement method for the hanger system can reduce all hangers’ stresses eff ectively to prolong service life and protect the cultural relic.

Preparation and luminescent properties of Tb3+/Sm3+ co-doped phosphate glasses for display device applications

Qian Zhang,Lei Han,Weizhen Liu,Weixiong You,Anxian Lu,Zhiwei Luo 한양대학교 세라믹연구소 2021 Journal of Ceramic Processing Research Vol.22 No.1

Development of orange light emitting materials cannot be ignored. In this paper, a novel Tb3+/Sm3+ co-doped P2O5-SrO-BaOZnO-glasses have been prepared. The prepared glasses consisted predominantly of Q2 units, and a small amount of Q0 andQ1 units. For absorption spectra of glasses, eight obvious absorption bands were found. Under the excitation of 402 nm and374 nm xenon lamp, the emission spectra and fluorescence lifetimes of glasses showed big difference. Under the excitation of374 nm xenon lamp, there was significant energy transfer process between Sm3+ and Tb3+ ions in glasses. The fluorescencedecay curves conformed to a double-exponential decay function, the average fluorescence lifetimes of glasses G02 ~ G10 were2.38 ms, 2.67 ms, 1.96 ms, 1.81 ms, and 1.61 ms with the increasing of Sm2O3 content, and the glasses emitted a distinct orangelight. The distinctive properties indicate that this system glass has potential applications in display devices.

Specific Alternation of Gut Microbiota and the Role of Ruminococcus gnavus in the Development of Diabetic Nephropathy

( Jinni Hong ),( Tingting Fu ),( Weizhen Liu ),( Yu Du ),( Junmin Bu ),( Guojian Wei ),( Miao Yu ),( Yanshan Lin ),( Cunyun Min ),( Datao Lin ) 한국미생물생명공학회 2024 Journal of microbiology and biotechnology Vol.34 No.3

In this study, we aim to investigate the precise alterations in the gut microbiota during the onset and advancement of diabetic nephropathy (DN) and examine the impact of Ruminococcus gnavus (R. gnavus) on DN. Eight-week-old male KK-Ay mice were administered antibiotic cocktails for a duration of two weeks, followed by oral administration of R. gnavus for an additional eight weeks. Our study revealed significant changes in the gut microbiota during both the initiation and progression of DN. Specifically, we observed a notable increase in the abundance of Clostridia at the class level, higher levels of Lachnospirales and Oscillospirales at the order level, and a marked decrease in Clostridia_UCG-014 in DN group. Additionally, there was a significant increase in the abundance of Lachnospiraceae, Oscillospiraceae, and Ruminococcaceae at the family level. Moreover, oral administration of R. gnavus effectively aggravated kidney pathology in DN mice, accompanied by elevated levels of urea nitrogen (UN), creatinine (Cr), and urine protein. Furthermore, R. gnavus administration resulted in down-regulation of tight junction proteins such as Claudin-1, Occludin, and ZO-1, as well as increased levels of uremic toxins in urine and serum samples. Additionally, our study demonstrated that orally administered R. gnavus up-regulated the expression of inflammatory factors, including nucleotide-binding oligomerization domain-like receptor pyrin domain-containing protein 3 (NLRP3) and Interleukin (IL)-6. These changes indicated the involvement of the gut-kidney axis in DN, and R. gnavus may worsen diabetic nephropathy by affecting uremic toxin levels and promoting inflammation in DN.

Effect of CeO2 addition on crystallization and thermophysical properties of Li2O-ZnO-SiO2 glass-ceramics

Ruixue Li,Qian Zhang,Xingliang Peng,Weizhen Liu 한양대학교 세라믹연구소 2020 Journal of Ceramic Processing Research Vol.21 No.1

The effect of CeO2 addition on crystallization and thermo-physical properties of lithium zinc silicate (LZS) glasses containingLi2O-ZnO-SiO2-Al2O3-Na2O-P2O5 was investigated. The changes of CeO2 contents (2-8 wt.%) had an obvious influence on thetransition temperatures (Tg) and crystallization temperatures (Tc) of LZS glass-ceramics, and they increased with CeO2 contentincreasing. According to XRD analysis, CeO2 promoted the formation of cristobalite and β-spodumene crystals, and β-spodumene increased obviously. As the CeO2 content increasing, the microstructure and microhardness (being 6.88 Gpa at 880oC) of glass-ceramics had great changes. The average thermal expansion coefficient (20 - 450 oC) showed first increasing thendecreasing, having a wide range. The maximum of thermal expansion coefficient was obtained when the glass-ceramicscontained 4 wt.% CeO2, being 175×10−7 K−1 (at 700 oC) and 178×10−7 K−1 (at 880 oC) respectively. Excellent thermo-physicalproperties indicate the glass has greater potential application, such as being used as sealing glass.

Internal Mammary Sentinel Lymph Node Biopsy after Neoadjuvant Chemotherapy in Breast Cancer

Zhao Bi,Peng Chen,Jingjing Liu,Yanbing Liu,Pengfei Qiu,Qifeng Yang,Weizhen Zheng,Yongsheng Wang 한국유방암학회 2018 Journal of breast cancer Vol.21 No.4

Purpose: The definition of nodal pathologic complete response (pCR) after a neoadjuvant chemotherapy (NAC) just included the evaluation of axillary lymph node (ALN) without internal mammary lymph node. This study aimed to evaluate the feasibility of internal mammary-sentinel lymph node biopsy (IM-SLNB) in patients with breast cancer who underwent NAC. Methods: From November 2011 to 2017, 179 patients with primary breast cancer who underwent operation after NAC were included in this study. All patients received radiotracer injection with modified injection technology. IM-SLNB would be performed on patients with internal mammary sentinel lymph node (IMSLN) visualization. Results: Among the 158 patients with cN+ disease, the rate of nodal pCR was 36.1% (57/158). Among the 179 patients, the visualization rate of IMSLN was 31.8% (57/179) and was 12.3% (7/57) and 87.7% (50/57) among those with cN0 and cN+ disease, respectively. Furthermore, the detection rate of IMSLN was 31.3% (56/179). The success rate of IM-SLNB was 98.2% (56/57). The IMSLN metastasis rate was 7.1% (4/56), and all of them were accompanied by ALN metastasis. The number of positive ALNs in patients with IMSLN metastasis was 3, 6, 8, and 9. The pathology nodal stage had been changed from pN1/ pN2 to pN3b. The pathology stage had been changed from IIA/ IIIA to IIIC. Conclusion: Patients with visualization of IMSLN should perform IM-SLNB after NAC, especially for patients with cN+ disease, in order to complete lymph nodal staging. IM-SLNB could further improve the definition of nodal pCR and guide the internal mammary node irradiation.