Discrete-Time Chaotic Circuits for Implementation of Tent Map and Bernoulli Map

Discrete-time chaotic circuit implementations of a tent map and a Bernoulli map using switched-current （SI） techniques are presented. The two circuits can be constructed with 16 MOSFET＇s and 2 capacitors. The simulations and experiments built with commercially available IC＇s for the circuits have demonstrated the validity of the circuit designs. The experiment results also indicate that the proposed circuits are integrable by a standard CMOS technology. The implementations are useful for studies and applications of chaos.

Landslide Susceptibility Mapping Using RBFN-Based Ensemble Machine Learning Models

This study was aimed to prepare landslide susceptibility maps for the Pithoragarh district in Uttarakhand,India,using advanced ensemble models that combined Radial Basis Function Networks(RBFN)with three ensemble learning techniques:DAGGING(DG),MULTIBOOST(MB),and ADABOOST(AB).This combination resulted in three distinct ensemble models:DG-RBFN,MB-RBFN,and AB-RBFN.Additionally,a traditional weighted method,Information Value(IV),and a benchmark machine learning(ML)model,Multilayer Perceptron Neural Network(MLP),were employed for comparison and validation.The models were developed using ten landslide conditioning factors,which included slope,aspect,elevation,curvature,land cover,geomorphology,overburden depth,lithology,distance to rivers and distance to roads.These factors were instrumental in predicting the output variable,which was the probability of landslide occurrence.Statistical analysis of the models’performance indicated that the DG-RBFN model,with an Area Under ROC Curve(AUC)of 0.931,outperformed the other models.The AB-RBFN model achieved an AUC of 0.929,the MB-RBFN model had an AUC of 0.913,and the MLP model recorded an AUC of 0.926.These results suggest that the advanced ensemble ML model DG-RBFN was more accurate than traditional statistical model,single MLP model,and other ensemble models in preparing trustworthy landslide susceptibility maps,thereby enhancing land use planning and decision-making.

A Complete and Simple Solution to a Discrete-Time Finite-Capacity BMAP/D/c Queue

We consider a discrete-time multi-server finite-capacity queueing system with correlated batch arrivals and deterministic service times (of single slot), which has a variety of potential applications in slotted digital telecommunication systems and other related areas. For this queueing system, we present, based on Markov chain analysis, not only the steady-state distributions but also the transient distributions of the system length and of the system waiting time in a simple and unified manner. From these distributions, important performance measures of practical interest can be easily obtained. Numerical examples concerning the superposition of certain video traffics are presented at the end.

融合Mind Map优势助力完善线上线下教学衔接--以园林树木学树种识别教学为例

疫情当前,线上线下混合式教学已经成为课程教学新模式。树种识别是园林树木学教学的重点和难点,也是教学目的之一。由于课程涉及的树种种类繁多,知识点琐碎,专业术语抽象,再加上课时少任务重,使得教师在教学过程中无法将所有树种的特征逐一讲解到,学生在学习过程中也容易混淆,无法有效吸收知识点。因此,在课程的教学改革中,通过引入Mind Map帮助厘清知识框架,优化知识结构,搭建知识关联,不仅使教师授课过程更顺畅,而且能够激发学生在线学习的兴趣,促使学生养成“整理知识点”的良好习惯,使学习效率大幅度提高,从而创建高效的线上课堂,有效巩固混合式教学的教学效果。

磁共振T1rho序列、T2 mapping技术在膝关节早期软骨退变早期诊断中的评估价值

目的探讨磁共振T1rho序列、T2 mapping技术在膝关节早期软骨退变早期诊断中的评估价值。方法选取2020年1月至2022年11月在我院治疗的110例膝关节早期软骨退变患者(观察组),按照疾病严重程度分为轻度退变组及重度退变组,另选取同期在我院进行体检的64例健康者为对照组,受试者均行磁共振T1rho序列、T2 mapping技术扫描,测量受试者T2值及T1ρ值,探讨磁共振T1rho序列、T2 mapping技术在膝关节早期软骨退变早期诊断中的评估价值。结果观察组股骨外侧面、股骨内侧面、胫骨外侧面、胫骨内侧面、髋骨面T2值均明显高于对照组(P<0.05),重度退变亚组患者股骨外侧面、股骨内侧面、胫骨外侧面、胫骨内侧面、髋骨面T2值显著高于轻度退变者(P<0.05);观察组股骨内踝负重区、股骨内踝非负重区、股骨外踝负重区、股骨外踝非负重区、胫骨外侧平台区、胫骨内侧平台区、髌后软骨区磁共振T1ρ值明显高于对照组(P<0.05),重度退变亚组患者股骨内踝负重区、股骨内踝非负重区、股骨外踝负重区、股骨外踝非负重区、胫骨外侧平台区、胫骨内侧平台区、髌后软骨区磁共振T1ρ值明显高于轻度退变亚组患者(P<0.05);磁共振T1rho序列在膝关节早期软骨退变中早期诊断及严重程度评估中的的诊断ROC值及特异度明显高于T2 mapping技术(P<0.05),但后者具有更高的敏感度(P<0.05)。结论磁共振T1rho序列、T2 mapping技术均能有效反映膝关节早期软骨退变中软骨组织学成分变化情况,还可为膝关节软骨退变严重程度评估提供客观依据,二者具有一定互补价值。

MR T2^(*)mapping成像技术定量评价腰椎小关节炎软骨损伤

背景:腰椎小关节炎是引起下腰痛的一个主要原因,目前主要依靠MRI进行初步定性诊断,但仍有一定漏诊、误诊的概率发生,因此MR T2^(*)mapping成像技术有望成为定量检查腰椎小关节炎软骨损伤的重要检测手段。目的:探讨MR T2^(*)mapping成像技术在定量分析腰椎小关节炎软骨损伤退变中的应用价值。方法:收集南京医科大学第四附属医院2020年4月至2022年3月门诊或住院合并下腰痛共110例患者,设为病例组;同时招募无症状志愿者80例,设为对照组。对所有纳入对象L1-S1的小关节行3.0 T MR扫描,获取T2^(*)mapping横断位图像和T2WI图像,分别对所有小关节软骨进行Weishaupt分级及T2^(*)值测量,收集数据并行统计学分析。不同小关节Weishaupt分级之间小关节软骨T2^(*)值比较采用单因素方差分析。结果与结论:①经统计分析发现,病例组腰椎小关节软骨T2^(*)值(17.6±1.5)ms明显较对照组(21.4±1.3)ms降低,差异有显著性意义(P<0.05);②在病例组中,随着腰椎小关节Weishaupt分级增加,小关节软骨T2^(*)值也呈逐渐下降趋势,且这种差异有显著性意义(P<0.05);③提示T2^(*)mapping能够较好地显示腰椎小关节软骨损伤的早期病理变化,腰椎小关节软骨的T2^(*)值能够定量评估腰椎小关节的软骨损伤程度;T2^(*)mapping成像技术能为影像学诊断腰椎小关节炎软骨早期损伤提供很好的理论依据,具有重要的临床应用价值。

MAP添加液对冰冻解冻去甘油红细胞保存的质量影响

目的观察冰冻解冻去甘油红细胞悬浮于MAP添加液中对保存效果的影响,探索最佳保存方式。方法本研究将采集后d 3的400 mL全血,离心制备成浓缩红细胞,使用ACP 215全自动血细胞仪,加入40%复方甘油溶液,置于-65℃超低温冰箱中保存30 d,解冻去甘油洗涤后,等量分离成两袋,以添加0.9%氯化钠溶液为对照组;添加MAP为实验组,两组保存于2~6℃冷藏条件下,分别于0、1、3、5、7、14 d取样检测血液学参数指标、溶血指标、细胞代谢指标,观察两组在14 d保存期内的质量变化情况。结果研究发现两组红细胞在解冻去甘油后6项质控项目包括容量、血红蛋白含量、游离血红蛋白含量、白细胞残留量、甘油残留量、无菌试验的检测值均符合《全血及成分血质量要求》(GB18469-2012);压积、红细胞计数、Hb洗涤后回收率、MCV符合《冰冻红细胞质量评价指标专家共识》检测限值,血小板残留量超过检测限值(≤1%);在14 d保存期内,两组的RBC、Hct、MCV和血红蛋白含量值无统计学意义;两组游离血红蛋白、溶血率和K+值随保存时间延长而增加,分别于3、5、7、14 d;3、5、7、14 d;14 d组间有统计学意义(P<0.05),两组红细胞渗透脆性于14 d组间有统计学意义(P<0.05);两组ATP、pH值随保存时间延长而下降,分别于3、5、7 d;1、3、5、7、14 d组间有统计学意义(P<0.05)。结论悬浮于MAP添加液中的冰冻解冻去甘油红细胞可将血液保存期延长至7 d,本研究为相关标准的制定提供参考依据。

番鸭VIPR1和miR-317以及MAP3K7和miR-244靶向关系的研究

试验旨在验证番鸭就巢相关miRNA与靶基因靶向关系。试验利用miRanda、PITA和RNAhybrid三个软件的交集预测miR-317和miR-244靶基因,构建VIPR1-pmirGLO/MAP3K7-pmirGLO野生型和突变型双荧光素酶重组载体,将miR-317/VIPR1-Wt和miR-244/MAP3K7-Wt分别共转染至鸭胚成纤维细胞,检测双荧光素酶活性。结果显示:与miR-NC组相比,miR-317/VIPR1-Wt共转染组相对荧光值显著降低(P<0.05);VIPR1突变后,miR-NC组与miR-317组的相对荧光值不显著(P>0.05),说明突变后完全抑制miR-317对VIPR1的结合作用,VIPR1与miR-317之间存在相互结合作用。与miR-NC组相比,miR-244/MAP3K7-Wt共转染组相对荧光值无显著性差异(P>0.05);MAP3K7突变后,miR-NC组与miR-244组的相对荧光值差异不显著(P>0.05),表明MAP3K7与miR-244之间不存在相互结合作用。研究提示,miR-317与VIPR1存在确切靶向结合位点,即VIPR1是miRNA miR-317的靶基因,而miR-244与MAP3K7不存在靶向关系。

Discrete-time Markov-based dynamic control approach for compressed sampling

To solve the problem that the signal sparsity level is time-varying and not known as a priori in most cases,a signal sparsity level prediction and optimal sampling rate determination scheme is proposed.The discrete-time Markov chain is used to model the signal sparsity level and analyze the transition between different states.According to the current state,the signal sparsity level state in the next sampling period and its probability are predicted.Furthermore,based on the prediction results,a dynamic control approach is proposed to find out the optimal sampling rate with the aim of maximizing the expected reward which considers both the energy consumption and the recovery accuracy.The proposed approach can balance the tradeoff between the energy consumption and the recovery accuracy.Simulation results show that the proposed dynamic control approach can significantly improve the sampling performance compared with the existing approach.

传统武术套路训练对大学生武术运动员膝关节软骨影响的T2-mapping功能磁共振成像研究

目的:本研究旨在通过T2-mapping功能磁共振影像学技术对大学生武术运动员膝关节软骨进行定量评估,探究传统武术套路训练对大学生武术运动员膝关节软骨的影响。方法:选取9名年龄介于18~25岁之间的大学生武术运动员作为实验组,同时选取18名普通健康的大学生作为对照组。在相同条件下,对两组分别进行右膝关节的T2-mapping磁共振检查,并将膝关节软骨分为股骨内侧髁、胫骨内侧髁、髌软骨、股骨外侧髁及胫骨外侧髁5个感兴趣区,比较实验组与对照组之间T2值的差异,分析各组膝关节软骨不同感兴趣区T2值的变化。结果:(1)不论性别,实验组和对照组各个膝关节面软骨感兴趣区的T2值均未见显著性差异(P>0.05);(2)男性对照组、女性对照组以及女性实验组的膝关节各感兴趣区T2值两两之间均无统计学差异(P>0.05);(3)男性实验组膝关节股骨外侧髁与胫骨内侧髁、髌软骨的T2值差异具有统计学意义(P<0.05)。结论:T2-mapping技术可通过无创手段定量评估传统武术套路训练对大学生膝关节软骨的影响。在长期传统武术套路训练后,男性大学生武术运动员的膝关节出现了异质性改变,因此在训练过程中应该注意调整方案,以实现针对性保护。

DWI联合T2 mapping序列鉴别前列腺癌与前列腺增生价值评估

目的探讨扩散加权成像(diffusion-weighted imaging,DWI)联合T2 mapping序列鉴别前列腺癌(prostate cancer,PCa)与前列腺增生(benign prostatic hyperplasia,BPH)的价值。材料与方法回顾性分析本院行3.0 T MRI检查且经病理证实的56例PCa患者及40例BPH患者资料。扫描序列包括T1WI、T2WI、DWI及T2 mapping序列。两名观察者分别测量两组病灶的表观扩散系数(apparent diffusion coefficient,ADC)值及T2值。采用组内相关系数(intra-class correlation coefficient,ICC)评估两名观察者测得参数值的一致性。采用独立样本t检验或Mann-Whitney U检验分析两组病例间ADC值及T2值的差异。Logistic回归用于分析差异具有统计学意义的参数及其与基线资料联合的诊断模型。采用受试者工作特征(receiver operating characteristic,ROC)曲线评估有差异参数及联合模型的诊断效能。采用DeLong检验比较ROC曲线下面积差异。采用Spearman相关系数分析ADC值与T2值相关性。结果两名观察者测量值一致性好(ICC>0.75)。PCa组的ADC值及T2值分别低于BPH组,差异具有统计学意义(P<0.01)。ADC值、T2值、ADC-T2及ADC-T2-年龄-总前列腺特异性抗原(total prostate specific antigen,TPSA)联合鉴别PCa与BPH的AUC值分别为0.843、0.830、0.896及0.927。DeLong检验显示ADC值与ADC-T2联合,ADC值、T2值、ADC-T2模型与ADC-T2-年龄-TPSA联合模型的ROC差异存在统计学意义(P<0.05)。ADC值与T2值呈正相关(r=0.331,P<0.01)。结论DWI及T2 mapping序列在鉴别PCa与BPH方面具有较好的价值,并且两序列联合临床指标时诊断效能提升,可为临床无创诊断PCa及BPH提供很好的指导意义。

A novel reaching law approach of quasi-sliding-mode control for uncertain discrete-time systems

A novel discrete-time reaching law was proposed for uncertain discrete-time system,which contained process noise and measurement noise.The proposed method reserves all the advantages of discrete-time reaching law,which not only decreases the band width of sliding mode and strengthens the system robustness,but also improves the dynamic performance and stability capability of the system.Moreover,a discrete-time sliding mode control strategy based on Kalman filter method was designed,and Kalman filter was employed to eliminate the influence of system noise.Simulation results show that there is no chattering phenomenon in the output of controller and the state variables of controlled system,and the proposed algorithm is also feasible and has strong robustness to external disturbances.

Attitude sensor fault diagnosis based on Kalman filter of discrete-time descriptor system

To diagnose the fault of attitude sensors in satellites, this paper proposes a novel approach based on the Kalman filter of the discrete-time descriptor system. By regarding the sensor fault term as the auxiliary state vector, the attitude measurement system subjected to the attitude sensor fault is modeled by the discrete-time descriptor system. The condition of estimability of such systems is given. And then a Kalman filter of the discrete-time descriptor system is established based on the methodology of the maximum likelihood estimation. With the descriptor Kalman filter, the state vector of the original system and sensor fault can be estimated simultaneously. The proposed method is able to esti-mate an abrupt sensor fault as well as the incipient one. Moreover, it is also effective in the multiple faults scenario. Simulations are conducted to confirm the effectiveness of the proposed method.

Adaptive Control and Function Projective Synchronization in 2D Discrete-Time Chaotic Systems

This study addresses the adaptive control and function projective synchronization problems between 2D Rulkov discrete-time system and Network discrete-time system. Based on backstepping design with three controllers, a systematic, concrete and automatic scheme is developed to investigate the function projective synchronization of discretetime chaotic systems. In addition, the adaptive control function is applied to achieve the state synchronization of two discrete-time systems. Numerical results demonstrate the effectiveness of the proposed control scheme.

LMI-based robust control of uncertain discrete-time piecewise affine systems

The main contribution of this paper is to present stability synthesis results for discrete-time piecewise affine （PWA） systems with polytopic time-varying uncertainties and for discrete-time PWA systems with norm-bounded uncertainties respectively.The basic idea of the proposed approaches is to construct piecewise-quadratic （PWQ） Lyapunov functions to guarantee the stability of the closed-loop systems.The partition information of the PWA systems is taken into account and each polytopic operating region is outer approximated by an ellipsoid,then sufficient conditions for the robust stabilization are derived and expressed as a set of linear matrix inequalities （LMIs）.Two examples are given to illustrate the proposed theoretical results.

Approximation law for discrete-time variable structure control systems

Two approximation laws of sliding mode for discrete-time variable structure control systems are proposed to overcome the limitations of the exponential approximation law and the variable rate approximation law. By applying the proposed approximation laws of sliding mode to discrete-time variable structure control systems, the stability of origin can be guaranteed, and the chattering along the switching surface caused by discrete-time variable structure control can be restrained effectively. In designing of approximation laws, the problem that the system control input is restricted is also considered, which is very important in practical systems. Finally a simulation example shows the effectiveness of the two approximation laws proposed.

Stability analysis and stabilization for discrete-time singular delay systems

Stability analysis and stabilization for discrete-time singular delay systems are addressed,respectively.Firstly,a sufficient condition for regularity,causality and stability for discrete-time singular delay systems is derived.Then,by applying the skill of matrix theory,the state feedback controller is designed to guarantee the closed-loop discrete-time singular delay systems to be regular,casual and stable.Finally,numerical examples are given to demonstrate the effectiveness of the proposed method.

LMI Consensus Condition for Discrete-time Multi-agent Systems

This paper examines a consensus problem in multiagent discrete-time systems, where each agent can exchange information only from its neighbor agents. A decentralized protocol is designed for each agent to steer all agents to the same vector. The design condition is expressed in the form of a linear matrix inequality. Finally, a simulation example is presented and a comparison is made to demonstrate the effectiveness of the developed methodology.

Variable structure control with sliding mode prediction for discrete-time nonlinear systems

A new variable structure control algorithm based on sliding mode prediction for a class of discrete-time nonlinear systems is presented. By employing a special model to predict future sliding mode value, and combining feedback correction and receding horizon optimization methods which are extensively applied on predictive control strategy, a discrete-time variable structure control law is constructed. The closed-loop systems are proved to have robustness to uncertainties with unspecified boundaries. Numerical simulation and pendulum experiment results illustrate that the closed-loop systems possess desired performance, such as strong robustness, fast convergence and chattering elimination.

Discrete-time movement model of a group of trains on a rail line with stochastic disturbance

This paper presents a discrete-time model to describe the movements of a group of trains, in which some operational strategies, including traction operation, braking operation and impact of stochastic disturbance, are defined. To show the dynamic characteristics of train traffic flow with stochastic disturbance, some numerical experiments on a railway line are simulated. The computational results show that the discrete-time movement model can well describe the movements of trains on a rail line with the moving-block signalling system. Comparing with the results of no disturbance, it finds that the traffic capacity of the rail line will decrease with the influence of stochastic disturbance. Additionally, the delays incurred by stochastic disturbance can be propagated to the subsequent trains, and then prolong their traversing time on the rail line. It can provide auxiliary information for rescheduling trains When the stochastic disturbance occurs on the railway.