[ $C^1$ ] Continuous Piecewise Rational Re-parameterization

Liang, Xiuxia,Zhang, Caiming,Zhong, Li,Liu, Yi Society for Computational Design and Engineering 2006 International Journal of CAD/CAM Vol.6 No.1

A new method to obtain explicit re-parameterization that preserves the curve degree and parametric domain is presented in this paper. The re-parameterization brings a curve very close to the arc length parameterization under $L_2$ norm but with less segmentation. The re-parameterization functions we used are $C^1$ continuous piecewise rational linear functions, which provide more flexibility and can be easily identified by solving a quadratic equation. Based on the outstanding performance of Mobius transformation on modifying pieces with monotonic parametric speed, we first create a partition of the original curve, in which the parametric speed of each segment is of monotonic variation. The values of new parameters corresponding to the subdivision points are specified a priori as the ratio of its cumulative arc length and its total arc length. $C^1$ continuity conditions are imposed to each segment, thus, with respect to the new parameters, the objective function is linear and admits a closed-form optimization. Illustrative examples are also given to assess the performance of our new method.

Formation Control of Multiple UAVs Incorporating Extended State Observer-Based Model Predictive Approach

Boyang Zhang,Xiuxia Sun,Shuguang Liu,Xiongfeng Deng 한국항공우주학회 2019 International Journal of Aeronautical and Space Sc Vol.20 No.4

This paper studies the extended state observer-based state space predictive control approach to deal with the multiple unmanned aerial vehicle formation flight with unknown disturbances. The distributed control problem for a class of multiple unmanned aerial vehicle systems with reference trajectory tracking and disturbance rejection is formulated. Firstly, a local distributed controller is designed by using the state space predictive control approach based on an error model to achieve stable tracking. Then, a feedforward compensation controller is introduced by using the extended state observer to estimate and compensate disturbances and improve the ability of anti-interference. Besides, the bounded stability of the designed extended state observer is analyzed as well. Finally, the simulation examples are provided to illustrate the validity of the proposed control structure.

Adaptive Differential Evolution-based Receding Horizon Control Design for Multi-UAV Formation Reconfiguration

Boyang Zhang,Xiuxia Sun,Shuguang Liu,Xiongfeng Deng 제어·로봇·시스템학회 2019 International Journal of Control, Automation, and Vol.17 No.12

The complicated and constrained reconfiguration optimisation for unmanned aerial vehicles (UAVs) is a challenge, particularly when multi-mission requirements are taken into account. In this study, we evaluate the use of the adaptive differential evolution-based centralised receding horizon control approach to achieve the formation reconfiguration along a given formation group trajectory for multiple unmanned aerial vehicles in a three-dimensional (3D) environment. A rolling optimisation approach which combines the receding horizon control method with the adaptive differential evolution algorithm is proposed, where the receding horizon control method divides the global control problem into a series of local optimisations and each local optimisation problem is solved by an adaptive differential evolution algorithm. Furthermore, a novel quadratic reconfiguration cost function with the topology information of UAVs is presented, and the asymptotic convergence of the rolling optimisation is analysed. Finally, simulation examples are provided to illustrate the validity of the proposed control structure.

Adaptive Differential Evolution-Based Distributed Model Predictive Control for Multi-UAV Formation Flight

Boyang Zhang,Xiuxia Sun,Shuguang Liu,Xiongfeng Deng 한국항공우주학회 2020 International Journal of Aeronautical and Space Sc Vol.21 No.2

The complicated formation flight for multi-unmanned aerial vehicles is a challenge, especially when multi-mission requirements are taken into account. This paper studies the adaptive differential evolution-based distributed model predictive control approach to deal with the multi-unmanned aerial vehicle flight achieving obstacle/collision avoidance and formation keeping simultaneously in the complex environment. Specifically, the distributed model predictive controller is designed to achieve stable flight for each unmanned aerial vehicle as well as taking the state and input saturation into account, where the local optimization problem is solved by the adaptive differential evolution algorithm. Besides, the adaptive adjustment to the prediction horizon for the model predictive controller is introduced, while the asymptotic convergence of the rolling optimization is analyzed as well. Finally, simulation examples are provided to illustrate the validity of the proposed control structure.

Expression of Serum PTTG1 in Laryngeal Carcinoma and Its Correlation to Prognosis

Kunpeng Ma,Xiuxia Sun,Limin Ma,Shenglin Zhang 대한이비인후과학회 2020 Clinical and Experimental Otorhinolaryngology Vol.13 No.1

Objectives. The purpose of this study was to investigate serum pituitary tumor transforming gene (PTTG1) expression in laryngeal carcinoma and its relationship with the clinical pathological characteristics and prognosis. Methods. Expression of serum PTTG1 was measured by enzyme-linked immunosorbent assay in 110 patients with laryngeal carcinoma and 60 patients with vocal cord polyps. Expression of the serum PTTG1 levels relationship with the clinicopathological characteristics and prognosis were analyzed. Results. In laryngeal carcinoma patients’ serum, the PTTG1 median concentration was 141.43 pg/mL (interquartile range [IQR], 111.387 to 160.837 pg/mL), significantly higher than that of the vocal cord polyp group of 94.01 pg/mL (IQR, 81.26 to 108.59 pg/mL), and the difference was statistically significant (z=–6.715, P<0.001). PTTG1 expression with lymph node metastasis, clinical stage, and patients with laryngeal carcinoma was significantly correlated with the tumor differentiation degree (P<0.05). The total survival rate of the PTTG1 high expression group was significantly lower than the low expression group, and the difference of total survival time of the two groups was statistically significant (P<0.001). Conclusion. The PTTG1 expression level can be used as an index for evaluating prognosis of laryngeal cancer. High PTTG1 expression is one of the factors of poor prognosis of laryngeal carcinoma patients.

Research on Energy Density and Specific Capacitance of Aqueous Supercapacitors

Yuanze Ma,Xiuxia Zhang,Yi Yang,Yanlin Li 한국전기전자재료학회 2021 Transactions on Electrical and Electronic Material Vol.22 No.6

As a novel energy storage device, supercapacitors with characteristics of large capacitance, high power density and long cycle life can meet the high requirements of energy storage units, having applied in portable instruments, data memory storage systems and electromobile, etc. However, a relatively low energy density limits the further employment of supercapacitors. This paper expounded the concept, composition and energy storage mechanism of supercapacitors in detail, and introduced the advantages and disadvantages of different types of supercapacitors as energy storage components. Meanwhile, the influence of electrode material and structure on the energy density and specific capacitance of aqueous supercapacitors were also discussed, and the problems existing in the current supercapacitors and the direction of future development were analyzed and summarized.

Study on Dynamic Guidance Obstacle Avoidance of UAV based on the Minimum Angle Shift

Xiong zhiyong,Yang Xiuxia,Zhang Yi,Hua Wei,Liu Xiaowei 보안공학연구지원센터 2016 International Journal of Security and Its Applicat Vol.10 No.3

With the extensive use of UAV, how to make the UAV avoid the obstacle and arrive at the destination has become a hot issue. To make the angle shift minimum, a method on dynamic guidance obstacle avoidance of UAV based on the minimum angle shift is proposed, considering the constraints such as the completion time of obstacle, the motor performance, the direction of velocity after obstacle avoidance and so on, determining the range of guidance parameters. In the meanwhile, the obstacle method is extended to 3D-space based on 2D. Moreover, numerical simulations are carried out to verify the effectiveness of the method.

Ketogenic Diet in Infants with Early-Onset Epileptic Encephalopathy and SCN2A Mutation

Xiaoyu Tian,Yange Zhang,Jinhong Zhang,Yan Lu,Xinyi Men,Xiuxia Wang 연세대학교의과대학 2021 Yonsei medical journal Vol.62 No.4

Research has shown mutations in the voltage-gated sodium channel gene SCN2A to be associated with developmental delaysand infantile seizures in patients with early-onset epileptic encephalopathies (EOEEs). Here, we report the case of an infant witha de novo SCN2A mutation with EOEE who had medically refractory seizures that improved with a ketogenic diet (KD) implementedat an age less than 2 months. On the day of his birth, the infant presented with a pattern of convulsions with dozens ofepisodes per day. An initial video electroencephalogram revealed poor reactivity of background activity, with multiple partial episodesstarting from the right temporal region, and abnormal electrical activity in the right hemisphere. The seizures previouslywere not controlled with successive therapy with phenobarbital, topiramate, and levetiracetam. Genetic testing revealed the presenceof a mutation in the SCN2A gene (c.4425C>G, p.Asn1475Lys). The infant’s seizures decreased significantly with a combinationof KD and medication. The present case exemplifies the potential for personalized genomics in identifying the etiology of anillness. Furthermore, the KD appears to feasible in infants younger than 2 months and might elicit good responses to EOEE associatedwith SCN2A mutation.

Study on Dynamic Guidance Obstacle Avoidance for UAV

Xiong Zhiyong,Yang Xiuxia,Zhang Yi,Hua Wei,Zhou Weiei 보안공학연구지원센터 2016 International Journal of Future Generation Communi Vol.9 No.8

With the flight environment becoming more and more complex, how to avoid the moving threat for the UAV under the dynamic environment and complete the mission become a key problem. With the idea of guidance, using the method of dimension reduction, the dynamic guidance obstacle avoidance method in three dimensional spaces is given. Considering the collision avoidance completion time and the UAV’s maneuverability, the parameters range of obstacle avoidance navigation law are deduced. Simulation results show the validity of the algorithm.

Poisoning effect of CaO on CeO2/TiO2 catalysts for selective catalytic reduction of NO with NH3

Ye Jiang,Xuechong Wang,Changzhong Bao,Shanbo Huang,Xiuxia Zhang,Xinwei Wang 한국화학공학회 2017 Korean Journal of Chemical Engineering Vol.34 No.6

The effect of CaO on CeO2/TiO2 catalysts prepared by a single step sol-gel method for selective catalytic reduction of NO with NH3 was investigated. The results showed that CaO could severely deactivate the CeO2/TiO2 catalysts. Based on the characterization results obtained by BET, XRD, XPS, H2-TPR and NH3-TPD, the deactivation by CaO of CeO2/TiO2 catalysts should be attributed to pore blockage, lower concentration of Ce on catalyst surface, reduction of Ce3+ and surface adsorbed oxygen, degradation of redox ability and decrease in NH3 adsorption capacity. The theoretical DFT results demonstrated that Ca atom could strongly interact with cerium oxygen, which inhibits the formation and hydrogenation of oxygen vacancies on catalyst surface.