Fundamental Trackability Problems for Iterative Learning Control

Generally, the classic iterative learning control(ILC)methods focus on finding design conditions for repetitive systems to achieve the perfect tracking of any specified trajectory,whereas they ignore a fundamental problem of ILC: whether the specified trajectory is trackable, or equivalently, whether there exist some inputs for the repetitive systems under consideration to generate the specified trajectory? The current paper contributes to dealing with this problem. Not only is a concept of trackability introduced formally for any specified trajectory in ILC, but also some related trackability criteria are established. Further, the relation between the trackability and the perfect tracking tasks for ILC is bridged, based on which a new convergence analysis approach is developed for ILC by leveraging properties of a functional Cauchy sequence(FCS). Simulation examples are given to verify the effectiveness of the presented trackability criteria and FCS-induced convergence analysis method for ILC.

Fine mapping and validation of a stable QTL for thousand-kernel weight in wheat(Triticum aestivum L.)

Thousand-kernel weight(TKW)is a measure of grain weight,a target of wheat breeding.The object of this study was to fine-map a stable quantitative trait loci(QTL)for TKW and identify its candidate gene in a recombinant inbred line(RIL)population derived from the cross of Kenong 9204(KN9204)and Jing411(J411).On a high-density genetic linkage map,24,26 and 25 QTL were associated with TKW,kernel length(KL),and kernel width(KW),respectively.A major and stable QTL,QTkw-2D,was mapped to an8.3 cM interval on chromosome arm 2DL.By saturation of polymorphic markers in its target region,QTkw-2D was confined to a 9.13 Mb physical interval using a secondary mapping population derived from a residually heterozygous line(F6:7).This interval was further narrowed to 2.52 Mb using QTkw-2D near-isogenic lines(NILs).NILs~(KN9204)had higher fresh and dry weights than NILsJ411at various grain-filling stages.The TKW and KW of NILs~(KN9204)were much higher than those of NILsJ411in field trials.By comparison of both DNA sequence and expression between KN9204 and J411,TraesCS2D02G460300.1(TraesKN2D01HG49350)was assigned as a candidate gene for QTkw-2D.This was confirmed by RNA sequencing(RNA-seq)of QTkw-2D NILs.These results provide the basis of map-based cloning of QTkw-2D,and DNA markers linked to the candidate gene may be used in marker-assisted selection.

Feedback iterative learning control for time-delay systems based on 2D analysis approach

This paper deals with the iterative learning control （ILC） design for multiple-input multiple-output （MIMO）,time-delay systems （TDS）.Two feedback ILC schemes are considered using the so-called two-dimensional （2D） analysis approach.It shows that continuous-discrete 2D Roesser systems can be developed to describe the entire learning dynamics of both ILC schemes,based on which necessary and sufficient conditions for their stability can be provided.A numerical example is included to validate the theoretical analysis.

Functional markers developed from TaGS3, a negative regulator of grain weight and size, for marker-assisted selection in wheat

The TaGS3 homoeologous genes(homoeologs)located on chromosomes 7 A,4 A,and7 D in hexaploid wheat were cloned.Relative expression analysis of the three Ta GS3 homoeologs revealed that the expression levels of TaGS3-4 A and TaGS3-7 D in developing grains were higher than that of TaGS3-7 A.Genetic evidence showed that Ta GS3 was a negative regulator of grain weight and grain size.Fifteen polymorphic sites and five haplotypes were detected in TaGS3-4 A.Two molecular markers were developed to distinguish the five haplotypes.Association analysis using 260 accessions from Chinese wheat mini-core collection(MCC)indicated that TaGS3-4 A affected thousand grain weight(TGW)and grain length(GL).HAP-4 A-1 and HAP-4 A-2 were favorable haplotypes that increased TGW and GL and had undergone strong selection during domestication of wheat.In addition,interaction of the TaGS3-4 A and TaGS3-7 D homoeologs had significant additive effects on the grain traits.Hap-4 A-1/Hap-7 D-2 was the best haplotype combination in increasing TGW and GL.The frequencies and geographic distributions of favorable TaGS3 haplotypes among 1388 wheat accessions from worldwide sources provided clues for selection of yield-related traits.Our findings demonstrated that TaGS3-4 A had significant effects on TGW and GL.Marker-assisted selection of HAP-4 A-1/2 combined with HAP-7 D-2 has potential to increase wheat yields.

Robust Optimization-Based Iterative Learning Control for Nonlinear Systems With Nonrepetitive Uncertainties

This paper aims to solve the robust iterative learning control(ILC)problems for nonlinear time-varying systems in the presence of nonrepetitive uncertainties.A new optimization-based method is proposed to design and analyze adaptive ILC,for which robust convergence analysis via a contraction mapping approach is realized by leveraging properties of substochastic matrices.It is shown that robust tracking tasks can be realized for optimization-based adaptive ILC,where the boundedness of system trajectories and estimated parameters can be ensured,regardless of unknown time-varying nonlinearities and nonrepetitive uncertainties.Two simulation tests,especially implemented for an injection molding process,demonstrate the effectiveness of our robust optimization-based ILC results.

Disagreement and Antagonism in Signed Networks: A Survey

Signed networks refer to a class of network systems including not only cooperative but also antagonistic interactions among nodes.Due to the existence of antagonistic interactions in signed networks,the agreement of nodes may not be established,instead of which disagreement behaviors generally emerge.This paper reviews several different disagreement behaviors in signed networks under the single-integrator linear dynamics,where two classes of topologies,namely,the static topology and the dynamic topology,are considered.For the static signed networks with the adjacency weights as(time-varying)scalars,we investigate the convergence behaviors and the fluctuation behaviors with respect to fixed topologies and switching topologies,respectively,and give some brief introductions on the disagreement behaviors of general time-varying signed networks.Correspondingly,several classes of behavior analysis approaches are also provided.For the dynamic signed networks with the adjacency weights as transfer functions or linear time-invariant systems,we show the specific descriptions and characteristics of them such that the disagreement behaviors can be obtained by resorting to the derived static signed graphs.Furthermore,we give their applications to the behavior analysis of static signed networks in the presence of high-order dynamics or communication delays.

Comparative genomic and transcriptomic analyses uncover the molecular basis of high nitrogen-use efficiency in the wheat cultivar Kenong 9204

Studying the regulatory mechanisms that drive nitrogen-use efficiency(NUE)in crops is important for sustainable agriculture and environmental protection.In this study,we generated a high-quality genome assembly for the high-NUE wheat cultivar Kenong 9204 and systematically analyzed genes related to nitrogen uptake and metabolism.By comparative analyses,we found that the high-affinity nitrate transporter gene family had expanded in Triticeae.Further studies showed that subsequent functional differentiation endowed the expanded family members with saline inducibility,providing a genetic basis for improving the adaptability of wheat to nitrogen deficiency in various habitats.To explore the genetic and molecular mechanisms of high NUE,we compared genomic and transcriptomic data from the high-NUE cultivar Kenong 9204(KN9204)and the low-NUE cultivar Jing 411 and quantified their nitrogen accumulation under high-and low-nitrogen conditions.Compared with Jing 411,KN9204 absorbed significantly more nitrogen at the reproductive stage after shooting and accumulated it in the shoots and seeds.Transcriptome data analysis revealed that nitrogen deficiency clearly suppressed the expression of genes related to cell division in the young spike of Jing 411,whereas this suppression of gene expression was much lower in KN9204.In addition,KN9204 maintained relatively high expression of NPF genes for a longer time than Jing 411 during seed maturity.Physiological and transcriptome data revealed that KN9204 was more tolerant of nitrogen deficiency than Jing 411,especially at the reproductive stage.The high NUE of KN9204 is an integrated effect controlled at different levels.Taken together,our data provide new insights into the molecular mechanisms of NUE and important gene resources for improving wheat cultivars with a higher NUE trait.

Indirect adaptive fuzzy-regulated optimal control for unknown continuous-time nonlinear systems

We present a novel indirect adaptive fuzzy-regulated optimal control scheme for continuous-time nonlinear systems with unknown dynamics,mismatches,and disturbances.Initially,the Hamilton-Jacobi-Bellman(HJB)equation associated with its performance function is derived for the original nonlinear systems.Unlike existing adaptive dynamic programming(ADP)approaches,this scheme uses a special non-quadratic variable performance function as the reinforcement medium in the actor-critic architecture.An adaptive fuzzy-regulated critic structure is correspondingly constructed to configure the weighting matrix of the performance function for the purpose of approximating and balancing the HJB equation.A concurrent self-organizing learning technique is designed to adaptively update the critic weights.Based on this particular critic,an adaptive optimal feedback controller is developed as the actor with a new form of augmented Riccati equation to optimize the fuzzy-regulated variable performance function in real time.The result is an online indirect adaptive optimal control mechanism implemented as an actor-critic structure,which involves continuous-time adaptation of both the optimal cost and the optimal control policy.The convergence and closed-loop stability of the proposed system are proved and guaranteed.Simulation examples and comparisons show the effectiveness and advantages of the proposed method.

A survey on distributed iterative learning control for transient formation

Distributed control is a hot topic in many research fields.Thanks to the development of communication and computation technologies,plenty of complex engineering problems can resort to the mechanism of distributed control.Of note is that most of the distributed control design only leverages the real-time information of agents,but as a consequence,only some specific steady-state objectives and/or system performances can be realized.Nonetheless,in many real scenarios,of particular importance are the transient behaviors of control systems.To deal with such problems in conventional situations.