Stabilization of Uncertain Fractional Memristor Chaotic Time⁃Delay System Based on Fractional Order Sliding Mode Control

Based on Lyapunov theorem and sliding mode control scheme,the chaos control of fractional memristor chaotic time⁃delay system was studied.In order to stabilize the system,a fractional sliding mode control method for fractional time⁃delay system was proposed.In addition,Lyapunov stability theorem was used to analyze the control scheme theoretically,which guaranteed the stability of commensurate and non⁃commensurate order systems with or without uncertainties and disturbances.Furthermore,to illustrate the feasibility of controller,the conditions for designing the controller parameters were derived.Finally,the simulation results presented the effectiveness of the designed strategy.

Sliding Mode Control of Fractional-Order Memristive System

A sliding mode controller for a fractional-order memristor-based chaotic system is designed to address its problem in stabilization control.Firstly,aphysically realizable fractional-order memristive chaotic system was introduced,which can generate a complex dynamic behavior.Secondly,a sliding mode controller based on sliding mode theory along with Lyapunov stability theory was designed to guarantee the occurrence of the sliding motion.Furthermore,in order to demonstrate the feasibility of the controller,a condition was derived with the designed controller＇s parameters,and the stability analysis of the controlled system was tested.A theoretical analysis shows that,under suitable condition,the fractional-order memristive system with a sliding mode controller comes to a steady state.Finally,numerical simulations are shown to verify the theoretical analysis.It is shown that the proposed sliding mode method exhibits a considerable improvement in its applications in a fractional-order memristive system.

Fractional-order heterogeneous memristive Rulkov neuronal network and its medical image watermarking application

This article proposes a novel fractional heterogeneous neural network by coupling a Rulkov neuron with a Hopfield neural network(FRHNN),utilizing memristors for emulating neural synapses.The study firstly demonstrates the coexistence of multiple firing patterns through phase diagrams,Lyapunov exponents(LEs),and bifurcation diagrams.Secondly,the parameter related firing behaviors are described through two-parameter bifurcation diagrams.Subsequently,local attraction basins reveal multi-stability phenomena related to initial values.Moreover,the proposed model is implemented on a microcomputer-based ARM platform,and the experimental results correspond to the numerical simulations.Finally,the article explores the application of digital watermarking for medical images,illustrating its features of excellent imperceptibility,extensive key space,and robustness against attacks including noise and cropping.

Development and validation of a UPLC–MS/MS assay for the determination of gemcitabine and its L-carnitine ester derivative in rat plasma and its application in oral pharmacokinetics

A simple and rapid UPLC–MS/MS method to simultaneously determine gemcitabine and its L-carnitine ester derivative(2’-deoxy-2’, 2’-difluoro-N-((4-amino-4-oxobutanoyl) oxy)-4-(trimethyl amm-onio) butanoate-cytidine, JDR) in rat plasma was developed and validated.The conventional plasma sample preparation method of nucleoside analogues is solidphase extraction(SPE) which is time-consuming and cost-expensive. In this study, gradient elution with small particles size solid phase was applied to effectively separate gemcitabine and JDR, and protein precipitation pretreatment was adopted to remove plasma protein and extract the analytes with high recovery(>81%). Method validation was performed as per the FDA guidelines, and the standard curves were found to be linear in the range of 5–4000 ng/ml for JDR and 4–4000 ng/ml for gemcitabine, respectively. The lower limit of quantitation(LLOQ)of gemcitabine and JDR was 4 and 5 ng/ml, respectively. The intra-day and inter-day precision and accuracy results were within the acceptable limits. Finally, the developed method was successfully applied to investigate the pharmacokinetic studies of JDR and gemcitabine after oral administration to rats.

Modeling and Dynamic Analysis of Fractional-Order Buck Converter in Continuous Conduction Mode

According to the fact that the actual inductor and actual capacitor are fractional, the mathematical and state-space averaging models of fractional order Buck converters in continuous conduction mode(CCM) are constructed by using fractional calculus theory. Firstly, the parameter conditions that ensure that the converter working in CCM is given and transfer functions are derived. Also, the inductor current and the output voltage are analyzed. Then the difference between the mathematical model and the circuit model are analyzed, and the effect of fractional order is studied by comparing the integer order with fractional order model. Finally, the dynamic behavior of the current-controlled Buck converter is investigated. Simulation experiments are achieved via the use of Matlab/Simulink. The experimental results verify the correctness of theoretical analysis, the order should be taken as a significant parameter. When the order is taken as a bifurcation parameter, the dynamic behavior of the converter will be affected and bifurcation points will be changed as order varies.

Dynamics Analysis of Fractional Order Memristive Time Delay Chaotic System and Circuit Implementation

The integer order memristive time delay chaotic system has attracted much attention and has been well discussed.However,the fractional order system is closer to the real system.In this paper,a nonlinear time delay chaotic circuit based on fractional order memristive system was proposed.Some dynamical properties,including equilibrium points,stability,bifurcation,and Lyapunov exponent of the oscillator,were investigated in detail by theoretical analyses and simulations.Moreover,the nonlinear phenomena of coexisting bifurcation and attractor was found.The phenomenon shows that the state of this oscilator was highly sensitive to its initial value,which is called coexistent oscillation in this paper.Finally,the results of the system circuit simulation accomplished by Multisim were perfectly consistent with theoretical analyses and numerical simulation.

Integration of phospholipid-drug complex into self-nanoemulsifying drug delivery system to facilitate oral delivery of paclitaxel

Self-nanoemulsifying drug delivery system(SNEDDS) has emerged as a promising platform to improve oral absorption of drugs with poor solubility and low permeability. However,large polarity molecules with insufficient lipid solubility,such as paclitaxel(PTX),would suffer from inferior formulation of SNEDDS due to poor compatibility. Herein,phospholipid-drug complex(PLDC) and SNEDDS were integrated into one system to facilitate oral delivery of PTX. First,PTX was formulated into PLDC in response to its inferior physicochemical properties. Then,the prepared PLDC was further formulated into SNEDDS by integrating these two drug delivery technologies into one system(PLDC-SNEDDS). After PLDC-SNEDDS dispersed in aqueous medium,nanoemulsion was formed immediately with an average particle size of ~30 nm. Furthermore,the nanomulsion of PLDC-SNEDDS showed good colloidal stability in both HCl solution(0.1 mol/l,p H 1.0) and phosphate buffer solution(PBS,p H 6.8). In vivo,PTX-PLDC-SNEDDS showed distinct advantages in terms of oral absorption efficiency,with a3.42-fold and 2.13-fold higher bioavailability than PTX-PLDC and PTX solution,respectively.Our results suggest that the integration of PLDC into SNEDDS could be utilized to facilitate the oral delivery of hydrophobic drugs with large polarity.

Hidden Attractors in a Delayed Memristive Differential System with Fractional Order and Chaos Synchronization

As an important research branch,memristor has attracted a range of scholars to study the property of memristive chaotic systems.Additionally,time⁃delayed systems are considered a significant and newly⁃developing field in modern research.By combining memristor and time⁃delay,a delayed memristive differential system with fractional order is proposed in this paper,which can generate hidden attractors.First,we discussed the dynamics of the proposed system where the parameter was set as the bifurcation parameter,and showed that with the increase of the parameter,the system generated rich chaotic phenomena such as bifurcation,chaos,and hypherchaos.Then we derived adequate and appropriate stability criteria to guarantee the system to achieve synchronization.Lastly,examples were provided to analyze and confirm the influence of parameter a,fractional order q,and time delayτon chaos synchronization.The simulation results confirm that the chaotic synchronization is affected by a,q andτ.

A Novel Flux-weakening Control Method with Quadrature Voltage Constrain for Electrolytic Capacitorless PMSM Drives

In electrolytic capacitorless permanent magnet synchronous motor(PMSM) drives, the DC-link voltage will fluctuate in a wide range due to the use of slim film capacitor. When the flux-weakening current is lower than-ψf/Ld during the high speed operation, the flux-weakening control loop will transform to a positive feedback mode, which means the reduction of flux-weakening current will lead to the acceleration of the voltage saturation, thus the whole system will be unstable. In order to solve this issue, this paper proposes a novel flux-weakening method for electrolytic capacitorless motor drives to maintain a negative feedback characteristic of the control loop during high speed operation. Based on the analysis of the instability mechanism in flux-weakening region, a quadrature voltage constrain mechanism is constructed to stabilize the system.Meanwhile, the parameters of the controller are theoretically designed for easier industrial application. The proposed algorithm is implemented on a 1.5 kW electrolytic capacitorless PMSM drive to verify the effectiveness of the flux-weakening performance.

Finite-time synchronization of uncertain fractional-order multi-weighted complex networks with external disturbances via adaptive quantized control

The finite-time synchronization of fractional-order multi-weighted complex networks(FMCNs)with uncertain parameters and external disturbances is studied.Firstly,based on fractional calculus characteristics and Lyapunov stability theory,quantized controllers are designed to guarantee that FMCNs can achieve synchronization in a limited time with and without coupling delay,respectively.Then,appropriate parameter update laws are obtained to identify the uncertain parameters in FMCNs.Finally,numerical simulation examples are given to validate the correctness of the theoretical results.

Dynamic Analysis of Fractional-Order Memristive Chaotic System

For the purpose of investigating the nonlinear dynamics of the system,a fractional-order Chua's circuit based on the memristor deriving from the integer-order counterparts is provided. Firstly,according to the Lyapunov's indirect method,the stability analysis of the memristive system is made,and it shows that when the fractional-orders parameter of memristive system passes a critical value,the system loses the stability and bifurcation occurs. Then the bifurcation and chaos behaviors of fractional-order memristive system are show n using bifurcation diagrams w ith varying fractional orders of the system and other parameters. Furthermore,the chaotic behaviors of memristive chaotic system are proved by the waveform,phase plot and largest Lyapunov exponent diagram. Finally,theoretical results are illustrated and validated with the given numerical simulations.

Hybrid Synchronization of Fractional-Order Complex Networks Model via Fractional Order Controller

For the purpose of investigating two complex networks' hybrid synchronization,a controller with fractional-order is provided.Regarding hybrid synchronization which includes the outer synchronization and inner synchronization,some hybrid synchronization's sufficient conditions according to the Lyapunov stability theorem and the LaSalle invariance principle are proposed.Theoretical analysis suggests that,only when the state of driving-response networks is outer synchronization and each network is in inner synchronization,two coupled networks' hybrid synchronization under some suitable conditions could be reached.Finally,theoretical results are illustrated and validated with the given numerical simulations.

UPLCeMS/MS for the determination of azilsartan in beagle dog plasma and its application in a pharmacokinetics study

The purpose of the study is to develop an ultra performance liquid chromatographytandem mass spectrometry(UPLCeMS/MS)to determinate the concentration of azilsartan in the dog plasma.After precipitated by methanol,the plasma sample containing azilsartan and diazepam(internal standard,IS)was determined by UPLCeMS/MS.The mobile phase consisted of acetonitrile-water was pumped at a flow rate of 0.3 ml/min in gradient elution.Kinetex 2.6 m XB-C18 column(50
2.1 mm,100Å;Phenomenex,USA)were used for LC separations.The column temperature was 30℃ and the injection volume was 5 ml.The electrospray ionization(ESI)and multiple reaction monitoring(MRM)were applied at the transitions of m/z 457/279(azilsartan)and m/z 285/193(diazepam),respectively.The developed method was identified a good linearity over a concentration range of 2.5e5000 ng/ml.The lower limit of quantitation(LLOQ)was 2.5 ng/ml.The intraday and inter-day precision(relative standard deviation,RSD%)were less than 10%and accuracy(relative error,RE%)was less than 5%at three quality control levels.The extraction recovery of azilsartan at three quality control levels were 82.41±0.68%,98.66±11.00%,102.43±0.82%.And the recovery for IS(100 ng/ml)was 91.75±0.54%.A validated UPLCeMS/MS method was firstly developed for the quantification of azilsartan in dog plasma and it was applied to the pharmacokinetics study.

具有拉伸塑性和明显增强的β弛豫行为的高能态非晶丝

本文通过Taylor-Uitovsky方法成功制备了高质量Fe基、Ni基、Co基非晶丝.与相同成分的传统非晶合金相比,该非晶丝表现出普遍的β弛豫增强和更高的能量状态,可以认为是高回春态的非晶丝.值得注意的是,这种非晶丝的能量增强率达到了216.38%,是目前各种增强非晶合金能量状态方法中的最高值.研究发现,β弛豫的增强归因于结构异质性引起的高能量状态,从而使得非晶丝具有优良的力学性能,跟相同成分的非晶条带相比,其断裂强度提高至3240 MPa,拉伸塑性应提高至1.7%.本研究从β弛豫的角度实现了高能态的非晶合金的制备,为打破强度和拉伸塑性之间的权衡提供了一个新见解.

Advances in artificial intelligence techniques drive the application of radiomics in the clinical research of hepatocellular carcinoma

Hepatocellular carcinoma(HCC)remains the most common malignancy to threaten public health globally.With advances in artificial intelligence techniques,radiomics for HCC management provides a novel perspective to solve unmet needs in clinical settings,and reveals pixel-level radiological information for medical imaging big data,correlating the radiological phenotype with targeted clinical issues.Conventional radiomics pipelines depend on handcrafted engineering features,and further deep learning-based radiomics pipelines are supplemented with deep features calculated via self-learning strategies.During the past decade,radiomics has been widely applied in accurate diagnoses and pathological or biological behavior evaluation,as well as in prognosis prediction.In this review,we systematically introduce the main pipelines of artificial intelligence-based radiomics and their efficacy in the clinical studies of HCC.