Policy Iteration for Optimal Control of Discrete-Time Time-Varying Nonlinear Systems

Aimed at infinite horizon optimal control problems of discrete time-varying nonlinear systems,in this paper,a new iterative adaptive dynamic programming algorithm,which is the discrete-time time-varying policy iteration(DTTV)algorithm,is developed.The iterative control law is designed to update the iterative value function which approximates the index function of optimal performance.The admissibility of the iterative control law is analyzed.The results show that the iterative value function is non-increasingly convergent to the Bellman-equation optimal solution.To implement the algorithm,neural networks are employed and a new implementation structure is established,which avoids solving the generalized Bellman equation in each iteration.Finally,the optimal control laws for torsional pendulum and inverted pendulum systems are obtained by using the DTTV policy iteration algorithm,where the mass and pendulum bar length are permitted to be time-varying parameters.The effectiveness of the developed method is illustrated by numerical results and comparisons.

中医体质学与免疫学的相关性研究

中医体质学是以中医理论为指导,研究人类体质特征、体质类型的生理病理特点,和阐述人体体质与疾病、防治及养生及分析疾病反应状态、病变性质、发展趋向的学科,是一门从宏观辨证研究人体控制系统平衡与失衡及调控,与传统科学相结合的交叉性、应用性学科。免疫学是从微观、定量研究疾病本质,机体的防御、自稳和免疫监视功能的正常与否及其对疾病发生、类别、治疗关系的学科。我们旨在研究中医体质学与免疫学内在规律的本质,期冀努力探索更多免疫调节中草药改善机体免疫状态,为中西医结合理论在实践基础上的结合产生质的飞跃。

Classification of traditional Chinese medicine constitution based on facial features in color images

Objective:To explore the possible correlation between traditional Chinese medicine(TCM)constitution and facial features in color images and to improve the accuracy of automated constitution classification.Methods:Color images were taken of 5150 individuals of different professions.Automated face detection and key point positioning were performed on the collected images,which were then transformed into a standard size.The relationship between facial features and TCM constitution based on the red,green,blue(RGB)pixel and the local binary pattern(LBP)texture features was explored.Results:The overall accuracy rate and robustness of TCM constitution classification based on RGB features were low.Classification results of the phlegm-dampness,damp-heat,blood stasis,and balance constitutions achieved high accuracy rates.Classification accuracy rate using the LBP texture feature was higher than that of the RGB feature,with the best accuracy observed for the balance constitution.Conclusion:Application of computer image acquisition and processing of facial features may serve as an adjunct to the TCM diagnostic method of inspection.

Association between body-constitution type and vascular endothelial dysfunction: A cross-sectional study in an adult obese/ overweight population

Objective:To measure vascular endothelial function (VED) in obese/overweight people grouped according to the constitutional theory of traditional Chinese medicine (TCM).We wished to predict the risk of VED and cardiovascular diseases in obese/overweight populations.Methods:This was a cross-sectional study.Eighty-six obese/overweight volunteers from Beijing Chao-Yang Hospital were enrolled and divided into four groups based on body-constitution type:phlegm dampness (PD);phlegm dampness with blood stasis (PDBS);qi-deficiency (QD);balance (BA).Height,weight,waist circumference and hip circumference were measured,and percent body fat and reactive hyperemia index (RHI) calculated.Levels of vascular endothelial growth factor (VEGF),von Willebrand factor (vWF) and plasma endothelial-1 (ET-1) were detected by immunohistochemistry.Results:The RHI and vWF levels in the PDBS group were significantly lower than those in the BA group and QD group (P <.05),but there was no significant difference compared with the PD group (P >.05).These two indicators displayed no significant differences among BA,QD,and PD groups (P >.05).There was no significant difference among the four groups in level of ET-1 or VEGF (P >.05).Conclusion:Of the four indicators selected,the RHI and vWF displayed significant differences between the PDBS group and BA group,and between the PDBS group and QD group.Hence,in an obese/overweight population with different constitutional types,compared with BA and QD groups,a relatively higher risk of suffering from VED was detected in the PDBS group.Meanwhile,this study provides the experimental basis for confirming the feasibility of constitutional classification in obese/overweight population.

The successful treatment for cardiac tamponade during radiofrequency ablation of hepatocellular carcinoma

To the Editor:Hepatocellular carcinoma(HCC)is the second most common cause of cancer-related death worldwide[1].Repeated liver resection remains a valid and safe curative therapy option for recurrent HCC in a minority of patients,because of multifocal intrahepatic or extra-hepatic recurrence and tumors in unresectable locations[2].HCC nodules less than 3 cm located in the hepatic dome beneath the diaphragm may represent one of the most difficult sites for resection[3].Therefore,some local invasive therapies,such as radiofrequency ablation(RFA),microwave ablation,transarterial chemoembolization(TACE)and laser hyperthermia,have been developed and applied in clinical HCC treatment[4].RFA has high frequency energy which heats the surrounding tissues and causes severe complications such as acute massive hemorrhage,thermal injury to viscera,pneumothorax and cardiac tamponade[5].

Lanthanide-based ratiometric luminescence nanothermometry

Luminescent nanothermometry can precisely and remotely measure the internal temperature of objects at nanoscale precision,which,therefore,has been placed at the forefront of scientific attention.In particular,due to the high photochemical stability,low toxicity,rich working mechanisms,and superior thermometric performance,lanthanide-based ratiometric luminesencent thermometers are finding prevalent uses in integrated electronics and optoelectronics,property analysis of in-situ tracking,biomedical diagnosis and therapy,and wearable e-health monitoring.Despite recent progresses,it remains debate in terms of the underlying temperature-sensing mechanisms,the quantitative characterization of performance,and the reliability of temperature readouts.In this review,we show the origin of thermal response luminescence,rationalize the ratiometric scheme or thermometric mechanisms,delve into the problems in the characterization of thermometric performance,discuss the universal rules for the quantitative comparison,and showcase the cutting-edge design and emerging applications of lanthanide-based ratiometric thermometers.Finally,we cast a look at the challenges and emerging opportunities for further advances in this field.

Gene expression signatures for phlegm-dampness constitution of Chinese Medicine

Dear Editor, The term ＂individualized medicine＂ was first used in Bio- chemistry Individuality in 1956 by Williams （Williams et al., 1956）. With the emergence of the post-genome era in the 21 st century, individualized precision medicine has attracted increasing attention. In traditional Chinese medicine （TCM）, there is also concept of individualized medicine, which is known as the Chinese constitutional theory, proposed in the 1970s （Wang, 2012）. According to this theory, the human population is divided into nine constitutions, including one balanced constitution （Normality） and eight unbalanced constitutions （Yang-deficient, Yin-deficient, Qi-deficient,