Adaptive Optimal Discrete-Time Output-Feedback Using an Internal Model Principle and Adaptive Dynamic Programming

In order to address the output feedback issue for linear discrete-time systems, this work suggests a brand-new adaptive dynamic programming(ADP) technique based on the internal model principle(IMP). The proposed method, termed as IMP-ADP, does not require complete state feedback-merely the measurement of input and output data. More specifically, based on the IMP, the output control problem can first be converted into a stabilization problem. We then design an observer to reproduce the full state of the system by measuring the inputs and outputs. Moreover, this technique includes both a policy iteration algorithm and a value iteration algorithm to determine the optimal feedback gain without using a dynamic system model. It is important that with this concept one does not need to solve the regulator equation. Finally, this control method was tested on an inverter system of grid-connected LCLs to demonstrate that the proposed method provides the desired performance in terms of both tracking and disturbance rejection.

SMSTracker:A Self-Calibration Multi-Head Self-Attention Transformer for Visual Object Tracking

Visual object tracking plays a crucial role in computer vision.In recent years,researchers have proposed various methods to achieve high-performance object tracking.Among these,methods based on Transformers have become a research hotspot due to their ability to globally model and contextualize information.However,current Transformer-based object tracking methods still face challenges such as low tracking accuracy and the presence of redundant feature information.In this paper,we introduce self-calibration multi-head self-attention Transformer(SMSTracker)as a solution to these challenges.It employs a hybrid tensor decomposition self-organizing multihead self-attention transformermechanism,which not only compresses and accelerates Transformer operations but also significantly reduces redundant data,thereby enhancing the accuracy and efficiency of tracking.Additionally,we introduce a self-calibration attention fusion block to resolve common issues of attention ambiguities and inconsistencies found in traditional trackingmethods,ensuring the stability and reliability of tracking performance across various scenarios.By integrating a hybrid tensor decomposition approach with a self-organizingmulti-head self-attentive transformer mechanism,SMSTracker enhances the efficiency and accuracy of the tracking process.Experimental results show that SMSTracker achieves competitive performance in visual object tracking,promising more robust and efficient tracking systems,demonstrating its potential to providemore robust and efficient tracking solutions in real-world applications.

Doped ceramics of indium oxides for negative permittivity materials in MHz-kHz frequency regions

Negative permittivity has been widely studied in various metamaterials and percolating composites, of which the anomalous dielectric behavior was attributed to critical structural properties of building blocks.Herein, mono-phase ceramics of indium tin oxides(ITO) were sintered for epsilon-negative materials in MHz-k Hz frequency regions. Electrical conductivity and complex permittivity were analyzed with DrudeLorentz oscillator model. Carriers’ characters were measured based on Hall effect and the magnitude and frequency dispersion of negative permittivity were mainly determined by carrier concentration.Temperature-dependent dielectric properties further proved the epsilon-negative behaviors were closely associated with free carriers’ collective responses. It’s found that negative permittivity of ITO ceramics was mainly caused by plasma oscillations of free carriers, while the dielectric loss was mainly attributed to conduction loss. Negative permittivity realized here was related to materials intrinsic nature and this work preliminarily determined the mechanism of negative permittivity in doped ceramics from the perspective of carriers.

Epsilon-negative BaTiO_(3)/Cu composites with high thermal conductivity and yet low electrical conductivity

Epsilon-negative materials with high thermal conductivity and low electrical conductivity are of great importance for high power microwave devices.In this work,BaTiO_(3)/Cu composites,as a class of epsilonnegative materials,are rationally designed to achieve a high thermal conductivity yet maintaining the electrical insulative character.Negative permittivity behavior induced by dielectric resonance and plasma oscillation is observed in these BaTiO_(3)/Cu composites,which can be explained by the Lorentz and Drude model respectively.An outstanding absorption ability is achieved near the zero-cross point of the permittivity.Benefiting from the positive temperature coefficient of resistance and the weak temperature dependence of thermal conductivity in BaTiO_(3)/Cu composites,sample containing 22.3 vol% of Cu content exhibits a thermal conductivity of up to 17.7 W/(m·k)and an electrical conductivity down to 0.0022(Ω cm)^(-1) at 150℃.Therefore,BaTiO_(3)/Cu composite is a promising candidate for applications in electromagnetic attenuation and thermal management.

Targeted Double Negative Properties in Silver/Silica Random Metamaterials by Precise Control of Microstructures

Te mechanism of negative permittivity/permeability is still unclear in the random metamaterials,where the precise control of microstructure and electromagnetic properties is also a challenge due to its random characteristic.Here silver was introduced into porous SiO_(2) microsphere matrix by a self-assemble and template method to construct the random metamaterials.Te distribution of silver was restricted among the interstices of SiO_(2) microspheres,which lead to the precise regulation of electrical percolation(from hoping to Drude-type conductivity)with increasing silver content.Negative permittivity came from the plasma-like behavior of silver network,and its value and frequency dispersion were further adjusted by Lorentz-type dielectric response.During this process,the frequency of epsilon-near-zero(ENZ)could be adjusted accordingly.Negative permeability was well explained by the magnetic response of eddy current in silver micronetwork.Te calculation results indicated that negative permeability has a linear relation with ω^(0.5),showing a relaxation-type spectrum,diferent from the“magnetic plasma”of periodic metamaterials.Electromagnetic simulations demonstrated that negative permittivity materials and ENZ materials,with the advantage of enhanced absorption(40dB)and intelligent frequency selection even in a thin thickness(0.1 mm),could have potentials for electromagnetic attenuation and shielding.Tis work provides a clear physical image for the theoretical explanation of negative permittivity and negative permeability in random metamaterials,as well as a novel strategy to precisely control the microstructure of random metamaterials.

Defect-induced insulator-metal transition and negative permittivity in La_(1-x)Ba_(x)CoO_(3)perovskite structure

The development of negative permittivity materials in multifunctional applications requests expansion of their operating frequency and improvement of stability of negative permittivity.Low electron density is beneficial to reduce plasma frequency so that negative permittivity is achieved in kHz region.Negative permittivity achieved by percolating composites is restricted in practicality due to its instability nature at high temperatures.To achieve temperature-stable negative permittivity in kHz region,monophase La_(1-x)Ba_(x)CoO_(3)ceramics were prepared,and the transition from dielectric to metal was elaborated in the perspective of electrical conductivity and negative permittivity.The plasma-like negative permittivity is attained in kHz region,which is interpreted by the collective oscillation of low electron density.The temperature-stable negative permittivity is based on the fact that the plasmonic state will not be undermined at high temperatures.In addition,zero-crossing behavior of real permittivity is observed in La_(0.9)Ba_(0.1)CoO_(3)sample,which provides a promising alternative to designing epsilon-near-zero materials.This work makes the La_(1-x)Ba_(x)CoO_(3)system a source material for achieving effective negative permittivity.

Integrative analysis of prognostic long non-coding RNAs with copy number variation in bladder cancer

Copy number variations(CNVs), which can affect the role of long non-coding RNAs(lncRNAs), are important genetic changes seen in some malignant tumors. We analyzed lncRNAs with CNV to explore the relationship between lncRNAs and prognosis in bladder cancer(BLCA). Messenger RNA(mRNA) expression levels, DNA methylation, and DNA copy number data of 408 BLCA patients were subjected to integrative bioinformatics analysis. Cluster analysis was performed to obtain different subtypes and differently expressed lncRNAs and coding genes. Weighted gene co-expression network analysis(WGCNA) was performed to identify the co-expression gene and lncRNA modules. CNV-associated lncRNA data and their influence on cancer prognosis were assessed with Kaplan-Meier survival curve. Multi-omics integration analysis revealed five prognostic lncRNAs with CNV, namely NR2 F1-AS1, LINC01138, THUMPD3-AS1, LOC101928489, and TMEM147-AS1, and a risk-score signature related to overall survival in BLCA was identified. Moreover, validated results in another independent Gene Expression Omnibus(GEO) dataset, GSE31684, were consistent with these results. Kyoto Encyclopedia of Genes and Genomes(KEGG) enrichment analysis revealed that the mitogen-activated protein kinase(MAPK) signaling pathway, focal adhesion pathway, and Janus kinase-signal transducers and activators of transcription(JAK-STAT) signaling pathway were enriched in a high-risk score pattern, suggesting that imbalance in these pathways is closely related to tumor development. We revealed the prognosis-related lncRNAs by analyzing the expression profiles of lncRNAs and CNVs, which can be used as prognostic biomarkers for BLCA.

Negative permittivity derived from inductive characteristic in the percolating Cu/EP metacomposites

Recently,increasing attention has been concentrated on negative permittivity with the development of the emerging metamaterials composed of periodic array structures.However,taking facile preparation into consideration,it is important to achieve negative permittivity behavior based on materials'intrinsic properties rather than their artificially periodic structures.In this paper,we proposed to fabricate the percolating composites with copper dispersed in epoxy(EP)resin by a polymerization method to realize the negative permittivity behavior.When Cu content in the composites reached to 80 wt%,the conductivity abruptly went up by three orders of magnitudes,suggesting a percolation behavior.Below the percolation threshold,the conductivity spectra conform to Jonscher's power law;when the Cu/EP composites reached to percolating state,the conductivity gradually reduced in high frequency region due to the skin effect.It is indicated that the conductive mechanism changed from hopping conduction to electron conduction.In addition,the permittivity did not increase monotonously with the increase of Cu content in the vicinity of percolation threshold,due to the presence of leakage current.Meanwhile,the negative permittivity conforming to Drude model was observed above the percolation threshold.Further investigation revealed that there was a constitutive relationship between the permittivity and the reactance.When conductive fillers are slightly above the percolation threshold,the inductive characteristic derived from conductive percolating network leads to the negative permittivity.Such epsilon-negative materials can potentially be applied in novel electrical devices,such as high-power microwave filters,stacked capacitors,negative capacitance field effect transistors and coil-free resonators.In addition,the design strategy based on percolating composites provides an approach to epsilon-negative materials.

Great enhancement of image details with high fidelity in a scintillator imager using an optical coding method

High-resolution lens-coupled indirect X-ray scintillator imagers are required by many imaging applications.However,the severe weakening of image details prevents its further performance improvement.Through our research,this image degradation is attributed to the broadband loss of the high-spatial-frequency information caused by the high refractive index.A technique known as high-spatial-frequency spectrum enhanced reconstruction is thus proposed to retrieve this information.A two-dimensional high-density array is covered on the scintillator’s exit surface and operates as an encoder based on which high-frequency information can be shifted to the low-frequency region to improve the signal-to-noise ratio.The experimental results show that the middle-high-frequency signal intensities can be increased by an order of magnitude or more,up to^50 times.Therefore,the image details can be effectively enhanced to break through the performance bottleneck of such widely used X-ray imagers for synchrotron radiation facilities or tabletop X-ray tubes.