Prescribed Performance Tracking Control of Time-Delay Nonlinear Systems With Output Constraints

The problem of prescribed performance tracking control for unknown time-delay nonlinear systems subject to output constraints is dealt with in this paper. In contrast with related works, only the most fundamental requirements, i.e., boundedness and the local Lipschitz condition, are assumed for the allowable time delays. Moreover, we focus on the case where the reference is unknown beforehand, which renders the standard prescribed performance control designs under output constraints infeasible. To conquer these challenges, a novel robust prescribed performance control approach is put forward in this paper.Herein, a reverse tuning function is skillfully constructed and automatically generates a performance envelop for the tracking error. In addition, a unified performance analysis framework based on proof by contradiction and the barrier function is established to reveal the inherent robustness of the control system against the time delays. It turns out that the system output tracks the reference with a preassigned settling time and good accuracy,without constraint violations. A comparative simulation on a two-stage chemical reactor is carried out to illustrate the above theoretical findings.

Generalized-Extended-State-Observer and Equivalent-Input-Disturbance Methods for Active Disturbance Rejection: Deep Observation and Comparison

Active disturbance-rejection methods are effective in estimating and rejecting disturbances in both transient and steady-state responses.This paper presents a deep observation on and a comparison between two of those methods:the generalized extended-state observer(GESO)and the equivalent input disturbance(EID)from assumptions,system configurations,stability conditions,system design,disturbance-rejection performance,and extensibility.A time-domain index is introduced to assess the disturbance-rejection performance.A detailed observation of disturbance-suppression mechanisms reveals the superiority of the EID approach over the GESO method.A comparison between these two methods shows that assumptions on disturbances are more practical and the adjustment of disturbance-rejection performance is easier for the EID approach than for the GESO method.

Control Design for Transient Performance

CONTROL systems are everywhere – chemical plants,energy systems, manufacturing, homes and buildings,automobiles and trains, medical devices, cellular telephones and internet, aircraft and spacecraft. Recent developments in these fields bring up the systems with the unprecedented scope, scale and complexity such as cyber-physical and human systems, and the required control task becomes more challenging than ever [1]。

Hyodeoxycholic acid protects the neurovascular unit against oxygen-glucose deprivation and reoxygenation-induced injury in vitro

Calculus bovis is commonly used for the treatment of stroke in traditional Chinese medicine. Hyodeoxycholic acid(HDCA) is a bioactive compound extracted from calculus bovis. When combined with cholic acid, baicalin and jas-minoidin, HDCA prevents hypoxia-reoxygenation-induced brain injury by suppressing endoplasmic reticulum stress-mediated apoptotic signaling. However, the effects of HDCA in ischemic stroke injury have not yet been studied. Neurovascular unit(NVU) dysfunction occurs in ischemic stroke. Therefore, in this study, we investigated the effects of HDCA on the NVU under ischemic conditions in vitro. We co-cultured primary brain microvascular endothelial cells, neurons and astrocytes using a transwell chamber co-culture system. The NVU was pre-treated with 10.16 or 2.54 μg/mL HDCA for 24 hours before exposure to oxygen-glucose deprivation for 1 hour. The cell counting kit-8 assay was used to detect cell activity. Flow cytometry and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling were used to assess apoptosis. Enzyme-linked immunosorbent assay was used to measure the expression levels of inflammatory cytokines, including interleukin-1β, interleukin-6 and tumor necrosis factor-α, and neurotrophic factors, including brain-derived neurotrophic factor and glial cell line-derived neurotrophic factor. Oxidative stress-related factors, such as superoxide dismutase, nitric oxide, malondialdehyde and γ-glutamyltransferase, were measured using kits. Pretreatment with HDCA significantly decreased blood-brain barrier permeability and neuronal apoptosis, significantly increased transendothelial electrical resistance and γ-glutamyltransferase activity, attenuated oxidative stress damage and the release of inflammatory cytokines, and increased brain-derived neurotrophic factor and glial cell line-derived neurotrophic factor expression. Our findings suggest that HDCA maintains NVU morphological integrity and function by modulating inflammation, oxidation stress, apoptosis, and the expression of neurotrophic factors. Therefore, HDCA may have therapeutic potential in the clinical management of ischemic stroke. This study was approved by the Ethics Committee of Experimental Animals of Beijing University of Chinese Medicine(approval No. BUCM-3-2016040201-2003) in April 2016.

Temporal alterations in pericytes at the acute phase of ischemia/reperfusion in the mouse brain

Pericytes,as the mural cells surrounding the microvasculature,play a critical role in the regulation of microcirculation;however,how these cells respond to ischemic stroke remains unclear.To determine the temporal alterations in pericytes after ischemia/reperfusion,we used the 1-hour middle cerebral artery occlusion model,which was examined at 2,12,and 24 hours after reperfusion.Our results showed that in the reperfused regions,the cerebral blood flow decreased and the infarct volume increased with time.Furthermore,the pericytes in the infarct regions contracted and acted on the vascular endothelial cells within 24 hours after reperfusion.These effects may result in incomplete microcirculation reperfusion and a gradual worsening trend with time in the acute phase.These findings provide strong evidence for explaining the“no-reflow”phenomenon that occurs after recanalization in clinical practice.

Identification of tRNA-derived Fragments and Their Potential Roles in Atherosclerosis

Objective Atherosclerosis(AS),a chronic inflammatory disease,is the basis of cardiovascular disease(CVD).Although the treatment has been greatly improved,AS still imposes a large burden on human health and the medical system,and we still need to further study its pathogenesis.As a novel biomolecule,transfer RNA-derived fragments(tRFs)play a key role in the progression of various disease.However,whether tRFs contribute to atherosclerosis pathogenesis remains unexplored.Methods With deep sequencing technology,the change of tRFs expression profiles in patients with AS compared to healthy control group was identified.The accuracy of the sequencing data was validated using RT qPCR.Subsequently,we predicted the potential target genes of tRFs by online miRNA target prediction algorithms.The potential functions of tRFs were evaluated with Gene Ontology(GO)and Kyoto Encyclopedia of Genes and Genomes(KEGG)pathway analyses.Results There were 13 tRFs differentially expressed between patients with AS and healthy controls,of which 2 were up-regulated and 11 were down-regulated.Validation by RT-qPCR analysis confirmed the sequencing results,and tRF-Gly-GCC-009 was highly up-regulated in the AS group based on the results of sequencing which was confirmed by RT-qPCR analysis.Furthermore,GO enrichment and KEGG pathway analyses indicated that 10 signaling pathways were related to tRF-Gly-GCC-009.These pathways might be physiopathological fundamentals of AS,mainly involving in Apelin signaling,Notch signaling and calcium signaling.Conclusion The results of our study provide important novel insight into the underlying pathogenesis and demonstrate that tRFs might be potential biomarkers and therapeutic targets for AS in the future.

Distributed Optimal Control for Traffic Networks with Fog Computing

This paper presents a distributed optimization strategy for large-scale traffic network based on fog computing. Different from the traditional cloud-based centralized optimization strategy, the fog-based distributed optimization strategy distributes its computing tasks to individual sub-processors, thus significantly reducing computation time. A traffic model is built and a series of communication rules between subsystems are set to ensure that the entire transportation network can be globally optimized while the subsystem is achieving its local optimization. Finally, this paper numerically simulates the operation of the traffic network by mixed-Integer programming, also, compares the advantages and disadvantages of the two optimization strategies.

Spectral properties of Pr:CNGG crystals grown by micro-pulling-down method

Pr^3+-doped calcium niobium gallium garnet(Pr:CNGG)single crystals with different Pr^3+concentrations are successfully grown by the micro-pulling-down(μ-PD)method.The crystal structure,room-temperature absorption spectra,and fluorescence spectra of Pr:CNGG crystals are measured and discussed.The fluorescence results indicate their large dependence on the doping concentration.The fluorescence lifetime of the 1D2 energy level is also determined.The results indicate that Pr:CNGG crystal could be a potential solid-state laser gain medium.

Spinocerebellar ataxia type 3 with dopamine-responsive dystonia:A case report

BACKGROUND Spinocerebellar ataxia type 3(SCA3)is a rare neurodegenerative disease with high genetic heterogeneity.SCA3 mainly manifests as progressive cerebellar ataxia accompanied by paralysis of extraocular muscles,dysphagia,lingual fibrillation,pyramidal tract sign,and extrapyramidal system sign.However,it rarely has clinical manifestations similar to Parkinson-like symptoms,and is even rarer in patients sensitive to dopamine.We report a patient initially diagnosed with dopamine-responsive dystonia who was ultimately diagnosed with SCA3 by genetic testing,which was completely different from the initial diagnosis.CASE SUMMARY A 40-year-old Chinese woman was admitted to hospital due to severe inflexibility.At the beginning of the disease,she presented with anxiety and sleep disorder.At the later stage,she presented with gait disorder,which was similar to Parkinson's disease.Her medical history was unremarkable,but her mother,grandmother,and uncle all had similar illnesses and died due to inability to take care of themselves and related complications.Laboratory and imaging examinations showed no abnormalities,but electromyography and electroencephalography revealed delayed somatosensory evoked potentials and slow background rhythm,respectively.Her symptoms fluctuated during the daytime,and we initially diagnosed her with dopamine-responsive dystonia.After treatment with lowdose levodopa,the patient’s symptoms were significantly improved,but the final genetic diagnosis was SCA3.CONCLUSION SCA3 has various clinical phenotypes and needs to be differentiated from Parkinson's syndrome and dopamine-responsive dystonia.

Effect of Majie Pingchuan cataplasm on epithelial-derived cytokines in asthmatic mice based on the"lung-skin-intestine"axis

Objective:To observe the effect of MJPC cataplasm on the content of epithelial-derived cytokines in lung,skin and intestine of asthmatic mice.Methods:C57/BL6 female mice were randomly divided into four groups:control group,asthma model group,dexamethasone group and MJPC cataplasm group.Ovalbumin sensitized and challenged asthmatic mouse models were established.The spleen index was calculated,and HE staining was used to observe the pathological change in lung tissues.The ova-specific IgE in the mouse serum and the content of TSLP in lung,skin and intestine were detected by enzyme-linked immunosorbent assay(ELISA).The expressions of TSLP mRNA and IL-33 mRNA in skin and intestinal tissue were detected by qRT-PCR.Results:Compared with the control group,the spleen index of mice in asthma model group was increased.Vascular congestion and edema,inflammatory cell infiltration and bronchial wall thickening were observed.The expressions of IgE in the mouse serum were significantly increased,and the content of TSLP in lung and skin tissue increased,but that in intestine tissue did not change significantly.The expression of TSLP mRNA was up-regulated in skin and intestinal tissues.The expression of IL-33 mRNA was up-regulated in skin tissue,but not in intestine,and the differences were statistically significant(P<0.05);Compared with the model group,MJPC cataplasm could decrease the spleen index and the expression of IgE in the mouse serum,improve the pathological damage of lung tissue in asthmatic mice,reduce the content of TSLP in lung,skin and intestinal tissue,increased the expression of TSLP mRNA in skin tissue,and down-regulate the expression of Il-33 mRNA in skin tissue and the expression of TSLP mRNA and IL-33 mRNA expression in intestinal tissue(P<0.05).Pearson correlation coefficient(r)of the content of TSLP between lung and skin was 0.689,that between lung and intestinal was-0.163,and that between skin and intestinal was-0.163,and the differences were not statistically significant(P>0.05).Conclusion:MJPC cataplasm improve airway inflammation by inhibiting the content of epithelial-derived cytokines on the"lung-skin-intestine"axis of asthmatic mice,and achieve the effect of treating asthm.

The enlightenment and application of“Laxative method used in early stage of Febrile Disease”in treating COVID-19

The theory of the TCM laxative method is rich in content.Doctors of past dynasties have used it to treat febrile diseases.And the theory of“Laxative method used in early stage of Febrile Disease”has been praised by later generations.It advocates chasing away evil influence early and paying attention to the laxative method to prevent the spread of disease.the Novel Coronavirus(COVID-19)Infectious Pneumonia belongs to the category of"epidemic"in traditional Chinese medicine.The reasonable application of the cathartic is an important way to provide a way out for evil.However,don’t be blind to use laxative method,you should get it at the right time.The treatment of COVID-19 has different solution at different stages.You should adapt to the changes of the disease to use cathartic.A case in here is attached for reference.

Randomized Algorithm for Determining Stabilizing Parameter Regions for General Delay Control Systems

This paper proposes a method for determining the stabilizing parameter regions for general delay control systems based on randomized sampling. A delay control system is converted into a unified state-space form. The numerical stability condition is developed and checked for sample points in the parameter space. These points are separated into stable and unstable regions by the decision function obtained from some learning method. The proposed method is very general and applied to a much wider range of systems than the existing methods in the literature. The proposed method is illustrated with examples.

Chinese Stock Price and Volatility Predictions with Multiple Technical Indicators

While a large number of studies have been reported in the literature with reference to the use of Regression model and Artificial Neural Network (ANN) models in predicting stock prices in western countries, the Chinese stock market is much less studied. Note that the latter is growing rapidly, will overtake USA one in 20 - 30 years time and thus be-comes a very important place for investors worldwide. In this paper, an attempt is made at predicting the Shanghai Composite Index returns and price volatility, on a daily and weekly basis. In the paper, two different types of prediction models, namely the Regression and Neural Network models are used for the prediction task and multiple technical indicators are included in the models as inputs. The performances of the two models are compared and evaluated in terms of di- rectional accuracy. Their performances are also rigorously compared in terms of economic criteria like annualized return rate (ARR) from simulated trading. In this paper, both trading with and without short selling has been consid- ered, and the results show in most cases, trading with short selling leads to higher profits. Also, both the cases with and without commission costs are discussed to show the effects of commission costs when the trading systems are in actual use.

Linear and Nonlinear Trading Models with Gradient Boosted Random Forests and Application to Singapore Stock Market

This paper presents new trading models for the stock market and test whether they are able to consistently generate excess returns from the Singapore Exchange (SGX). Instead of conventional ways of modeling stock prices, we construct models which relate the market indicators to a trading decision directly. Furthermore, unlike a reversal trading system or a binary system of buy and sell, we allow three modes of trades, namely, buy, sell or stand by, and the stand-by case is important as it caters to the market conditions where a model does not produce a strong signal of buy or sell. Linear trading models are firstly developed with the scoring technique which weights higher on successful indicators, as well as with the Least Squares technique which tries to match the past perfect trades with its weights. The linear models are then made adaptive by using the forgetting factor to address market changes. Because stock markets could be highly nonlinear sometimes, the Random Forest is adopted as a nonlinear trading model, and improved with Gradient Boosting to form a new technique—Gradient Boosted Random Forest. All the models are trained and evaluated on nine stocks and one index, and statistical tests such as randomness, linear and nonlinear correlations are conducted on the data to check the statistical significance of the inputs and their relation with the output before a model is trained. Our empirical results show that the proposed trading methods are able to generate excess returns compared with the buy-and-hold strategy.

Feature Selection for Time Series Modeling

In machine learning, selecting useful features and rejecting redundant features is the prerequisite for better modeling and prediction. In this paper, we first study representative feature selection methods based on correlation analysis, and demonstrate that they do not work well for time series though they can work well for static systems. Then, theoretical analysis for linear time series is carried out to show why they fail. Based on these observations, we propose a new correlation-based feature selection method. Our main idea is that the features highly correlated with progressive response while lowly correlated with other features should be selected, and for groups of selected features with similar residuals, the one with a smaller number of features should be selected. For linear and nonlinear time series, the proposed method yields high accuracy in both feature selection and feature rejection.

On disturbance rejection proportional-integral-differential control with model-free adaptation

In this paper,an adaptive disturbance-rejection proportional–integral–differential(PID)control method is proposed for a class of nonlinear systems.First,PID-type criterion is introduced in a model-free adaptive control(MFAC)framework,which gives an optimal control interpretation for PID controller.Then,the design of adaptive disturbance rejection PID is proposed based on this new interpretation to realize controller gain auto-tuning.Due to the ingenious integration of active disturbance rejection and adaptive mechanism,the proposed adaptive disturbance rejection PID control scheme exhibits better control performance than MFAC case.Furthermore,the boundedness of controller gain,the convergence of tracking error and the bounded-input–bounded-output stability are proved for the proposed control system.Finally,the effectiveness of the proposed method is verified by numerical simulation.

Development of an enzyme-linked immunosorbent assay using specific monoclonal antibodies against theacrine and its application

Tbeacrine （1,3,7,9-tetramethyluric acid）, a purine alkaloid similar to caffeine in its chemical structure, is isolated from edible Camellia assamica vat. kucha and has various pharmacological activities including hypnotic effects, anti-depressant effects, anti-inflammatory and analgesic effects, and a protective effect against stress-provoked liver damage. A rapid and simple assay is required to quantify theacrine in biological samples for pharmacokinetic studies in small animals. This study aimed to establish an enzyme-linked immunosorbent assay （ELISA） for theacrine quantification in blood. Herein, we successfully obtained monoclonal antibodies （MAbs） against theacrine, MAbs C11B5, and developed an ELISA method for the fast determination of theacrine in mouse blood. The range for calibration of theacrine by ELISA was 0.156-100 μg mL-1. The half maximum inhibitory concentration （IC50） value was 1.55 μg mL-1. The ELISA method lays a good foundation for the further research.

A new path planning method for bevel-tip flexible needle insertion in 3D space with multiple targets and obstacles

In this paper,a new bevel-tip flexible needle path planning method based on the bee-foraging learning particle swarm optimization(BFL-PSO)algorithm and the needle retraction strategy in 3D space is proposed to improve the puncture accuracy and shorten the puncture distance in the case of multiple puncture targets.First,the movement of the needle after penetrating the human body is analyzed,and the objective function which includes puncture path error,puncture path length,and collision function is established.Then,the BFL-PSO algorithm and the needle retraction strategy are analyzed.Finally,medical images of the tissue to be punctured are obtained by medical imaging instruments,i.e.,magnetic resonance(MR),and the 3D model of the punctured environment is constructed by 3D Slicer to obtain the environment information on targets and obstacles,and the path of flexible needle is carried out based on the BFL-PSO optimization algorithm and the needle retraction strategy.The simulation results show that,compared with other path planning methods in the related literature,the new path planning method proposed in this paper has higher path planning accuracy,shorter puncture distance,and good adaptability to multi-target path planning problems.