Nonintrusive data-based learning of a switched control heating system using POD,DMD and ANN

The aim of this work is to derive an accurate model of two-dimensional switched control heating system from data generated by a Finite Element solver. The nonintrusive approach should be able to capture both temperature fields, dynamics and the underlying switching control rule. To achieve this goal, the algorithm proposed in this paper will make use of three main ingredients: proper orthogonal decomposition (POD), dynamic mode decomposition (DMD) and artificial neural networks (ANN). Some numerical results will be presented and compared to the high-fidelity numerical solutions to demonstrate the capability of the method to reproduce the dynamics.     

Free boundary problem for a fully nonlinear and degenerate parabolic equation in an angular domain

This paper concerns with the problem of how to running an insurance company to maximize his total discounted expected dividends. In our model, the dividend rate is limited in $[0,M]$ and the company is allowed to transfer any proportion of risk by reinsuring. So there are two strategies which we call dividend strategy and reinsurance strategy. The objective function and the corresponding optimal two strategies are the solution and the two free boundaries of the following Barenblatt parabolic equation

$v_t?\underset{0\le a\le 1}{\max }?(\frac{1}{2}{a}^2{\sigma }^2{v}_{xx}+a\mu v_x)+cv?\underset{0\le l\le M}{\max }?[(1?v_x)l]=0$

under certain boundary conditions on an angular domain

$Q_T=\{(x,t)|0<x<Mt,0<t\le T\}.$

The main effort is to analyze the properties of the solution and the free boundaries to show the optimal decision for the insurance company.     

In vitro anticomplementary activity and quality evaluation of dried blossoms of Inula nervosa Wall. from different geographical origins

Blossoms of Inula nervosa Wall. (BINW) are traditionally used as an analgesic and antitussive in China. In this study, in vitro anticomplementary activities of crude extract from BINW in 21 batches and of extracts of four monomeric compounds were evaluated by the classical pathway. The effect of the region of origin on the quality of BINW was evaluated by fingerprint analysis for the first time. Furthermore, chemometric methods including similarity analysis and principal component analysis were employed to evaluate the quality of BINW. The nine major monomeric compounds were quantitated by ultra‐high‐performance liquid chromatography. All nine analytes demonstrated excellent linearity with recoveries ranging from 97.25% to 102.76%. The limits of detection and quantification were 0.07–12.20 μg/mL and 0.22–40.27 μg/mL, respectively. Results indicate that different regions of origin have a significant effect on the quality of BINW. Fingerprint analysis in combination with chemometrics and multi‐ingredient determination is an efficient and reliable approach for quality evaluation. The BINW samples from Yunnan had the highest ratio of 1,5‐dicaffeoylquinic acid and thymol; they also exhibited significantly higher anticomplementary activity than those from three other areas. This study successfully established a rapid and efficient method to evaluate the quality and biological activity of BINW.     

An improved generalized predictive control algorithm based on the difference equation CARIMA model for the SISO system with known strong interference

ABSTRACT

The single input single output (SISO) system with known strong interference is widely used in various occasions. Due to its strong interference, the control accuracy is hard to guarantee. To solve this problem, an improved generalized predictive control (IGPC) algorithm is developed. The IGPC firstly builds the difference equation CARIMA (Controlled Auto-Regressive Integrated Moving-Average) model of the SISO system and then treats the system as a two input single output (TISO) system and calculates its predictive vector, then transforms it into a SISO system and uses the TISO system predictive vector to calculate the SISO system control increment. A new parameter called phase coefficient is added to inhibit the control lag. Simulations are performed to make the comparison among the traditional GPC, PID control, velocity synchronization control (VSC), fuzzy adaptive PID control (FAPID), model-based robust PID control (BPID) and the IGPC. Results show that IGPC has best performance compared to the others. Finally, experiments are developed which proved that the IGPC algorithm has a higher accuracy in the SISO system with known strong interference than that of VSC.     

基于计算机视觉技术的茶叶品质随机森林感官评价方法研究

为弥补茶叶品质感官审评存在的缺陷，利用计算机视觉技术对茶叶品质进行快速无损评价研究。以碧螺春绿茶为对象，依据专家感官审评结果，将茶样分成4个等级；采用中值滤波及拉普拉斯算子对茶样图像进行预处理，并提取预处理后的茶样图像的颜色特征和纹理特征以表征茶叶图像的外形特征，利用随机森林算法对茶叶外形特征属性进行重要性排序；筛选出重要性较大的特征及随机森林算法中最优的决策树棵数建立感官评价模型，并与建立的支持向量机(SVM)模型性能相比较。结果表明：色调均值、色调标准差、绿体均值、平均灰度级、饱和度均值、红体均值、饱和度标准差、亮度均值、一致性等9个特征属性的重要性较大，且与感官审评特征描述结果相一致；当采用优选出的9个重要性较大的特征及决策数棵数为500时，建立的模型性能最优，模型总体判别率为95.75%，Kappa系数为0.933，OOB误差为5%，较SVM模型分别提高了3.5%，0.066，优选的9个重要性较大的图像特征与感官审评特征描述相一致。研究表明：利用随机森林方法筛选出对茶叶外形特征属性贡献最大的少数几个特征建立模型，模型性能就能达到很好的识别效果，模型得到简化，同时模型精度和稳定性都高于其他方法。     

Dynamics modeling and robotic-assist,leader-follower control of tractor convoys

This paper proposes a generalized dynamics model and a leader-follower control architecture for skid-steered tracked vehicles towing polar sleds. The model couples existing formulations in the literature for the powertrain components with the vehicle-terrain interaction to capture the salient features of terrain trafficability and predict the vehicles response. This coupling is essential for making realistic predictions of the vehicles traversing capabilities due to the power-load relationship at the engine output. The objective of the model is to capture adequate fidelity of the powertrain and off-road vehicle dynamics while minimizing the computational cost for model based design of leader-follower control algorithms. The leader-follower control architecture presented proposes maintaining a flexible formation by using a look-ahead technique along with a way point following strategy. Results simulate one leader-follower tractor pair where the leader is forced to take an abrupt turn and experiences large oscillations of its drawbar arm indicating potential payload instability. However, the follower tractor maintains the flexible formation but keeps its payload stable. This highlights the robustness of the proposed approach where the follower vehicle can reject errors in human leader driving.     

基于碳化硅衬底的宽禁带半导体外延

宽禁带半导体具备禁带宽度大、电子饱和飘移速度高、击穿场强大等优势,是制备高功率密度、高频率、低损耗电子器件的理想材料。碳化硅(SiC)材料具有热导率高、化学稳定性好、耐高温等优点,在SiC衬底上外延宽禁带半导体材料,对充分发挥宽禁带半导体材料的优势,并提升宽禁带半导体电子器件的性能具有重要意义。得益于SiC衬底质量持续提升及成本不断降低,基于SiC衬底的宽禁带半导体电子市场占比呈现逐年增加的态势。在SiC衬底上外延生长高质量的宽禁带半导体材料是提高宽禁带半导体电子器件性能及可靠性的关键瓶颈。本文综述了近年来国内外研究者们在SiC衬底上外延SiC、氮化镓(GaN)、氧化镓(Ga₂O₃)所取得的研究进展,并展望了SiC衬底上宽禁带半导体外延的发展及应用前景。