Achieving Spatial Multi-Point Focusing by Frequency Diversity Array

Electronics ◽  
2019 ◽  
Vol 8 (8) ◽  
pp. 883
Author(s):  
Shuai Ding ◽  
Yong-Mao Huang ◽  
Huan Tang ◽  
Maurizio Bozzi ◽  
Bing-Zhong Wang
Keyword(s):  
Far Field ◽  
Time Varying ◽  
Frequency Diversity ◽  
Multiple Targets ◽  
Numerical Examples ◽  
Time Period ◽  
Single Target ◽  
Operating Bandwidth ◽  
Frequency Diverse Array ◽  
Spatial Focusing

This paper proposes a class of frequency diverse array (FDA) for achieving time-varying spatial focusing for multiple targets. On the basis of single-target focusing of FDA, sequential focus at the four points is achieved by controlling the time period. The effects of frequency offset on the range of focusing area are derived. Since FDA is narrowband in nature, the relative operating bandwidth is limited to be 10%. Under the limitation of the bandwidth, the sequential multi-target focusing in the far-field is achieved. To validate the proposed method, numerical examples of eight-element FDA are reported and discussed.

scholarly journals Time-Varying Impedance Control of Port Hamiltonian System with a New Energy-Storing Tank

Complexity ◽  
2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Min Zheng ◽  
Tangqing Yuan ◽  
Tao Huang
Keyword(s):  
Control Method ◽  
Impedance Control ◽  
Conservative System ◽  
Time Varying ◽  
Control Performance ◽  
Singularity Problem ◽  
Numerical Examples ◽  
New Energy ◽  
Simulation Results ◽  
New Framework

In order to guarantee the passivity of a kind of conservative system, the port Hamiltonian framework combined with a new energy tank is proposed in this paper. A time-varying impedance controller is designed based on this new framework. The time-varying impedance control method is an extension of conventional impedance control and overcomes the singularity problem that existed in the traditional form of energy tank. The validity of the controller designed in this paper is shown by numerical examples. The simulation results show that the proposed controller can not only eliminate the singularity problem but can also improve the control performance.

Moving Load on a Laminated Composite

1974 ◽  
Vol 41 (3) ◽  
pp. 663-667 ◽  
Author(s):  
C. Sve ◽  
G. Herrmann
Keyword(s):  
Dynamic Response ◽  
Half Plane ◽  
Moving Load ◽  
Formal Solution ◽  
Laminated Composite ◽  
Laplace Transforms ◽  
Layered Material ◽  
Effective Stiffness ◽  
Far Field ◽  
Numerical Examples

A solution is presented for the dynamic response of a periodically laminated half plane that consists of alternating layers of two different materials and is subjected to a moving load. The laminations are parallel to the surface of the half plane, and the velocity of the load is steady and supersonic. An effective stiffness theory developed by Sun, Achenbach, and Herrmann is used to model the layered material, and the formal solution is obtained with the aid of Laplace transforms. A far-field solution is constructed with the head-of-the-pulse procedure, and several numerical examples are presented.

scholarly journals Robust Stability Analysis of Neutral-Type Hybrid Bidirectional Associative Memory Neural Networks with Time-Varying Delays

2014 ◽  
Vol 2014 ◽  
pp. 1-12
Author(s):  
Wei Feng ◽  
Simon X. Yang ◽  
Haixia Wu
Keyword(s):  
Neural Networks ◽  
Stability Analysis ◽  
Associative Memory ◽  
Robust Stability ◽  
Neutral Type ◽  
Time Varying ◽  
Bidirectional Associative Memory ◽  
Numerical Examples ◽  
Network Parameters ◽  
Robust Stability Analysis

The global asymptotic robust stability of equilibrium is considered for neutral-type hybrid bidirectional associative memory neural networks with time-varying delays and parameters uncertainties. The results we obtained in this paper are delay-derivative-dependent and establish various relationships between the network parameters only. Therefore, the results of this paper are applicable to a larger class of neural networks and can be easily verified when compared with the previously reported literature results. Two numerical examples are illustrated to verify our results.

scholarly journals Passivity of Memristive BAM Neural Networks with Probabilistic and Mixed Time-Varying Delays

2018 ◽  
Vol 2018 ◽  
pp. 1-25
Author(s):  
Weiping Wang ◽  
Meiqi Wang ◽  
Xiong Luo ◽  
Lixiang Li ◽  
Wenbing Zhao
Keyword(s):  
Neural Networks ◽  
Probability Distribution ◽  
Linear Matrix ◽  
Time Varying ◽  
Bam Neural Networks ◽  
Bernoulli Distribution ◽  
Matrix Inequalities ◽  
Bidirectional Associative Memory ◽  
Leakage Delays ◽  
Numerical Examples

This paper is concerned with the passivity problem of memristive bidirectional associative memory neural networks (MBAMNNs) with probabilistic and mixed time-varying delays. By applying random variables with Bernoulli distribution, the information of probability time-varying delays is taken into account. Furthermore, we consider the probability distribution of the variation and the extent of the delays; therefore, the results derived are less conservative than in the existing papers. In particular, the leakage delays as well as distributed delays are all taken into consideration. Based on appropriate Lyapunov-Krasovskii functionals (LKFs) and some useful inequalities, several conditions for passive performance are established in linear matrix inequalities (LMIs). Finally, numerical examples are given to demonstrate the feasibility of the presented theories, and the results reveal that the probabilistic and mixed time-varying delays have an unstable influence on the system and should not be ignored.

scholarly journals A New Stability Criterion for Systems with Distributed Time-Varying Delays via Mixed Inequalities Method

Complexity ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-6
Author(s):  
Jun-kang Tian ◽  
Yan-min Liu
Keyword(s):  
Linear Matrix Inequalities ◽  
Stability Criterion ◽  
Linear Matrix ◽  
Time Varying ◽  
Matrix Inequalities ◽  
Numerical Examples ◽  
Delay Dependent ◽  
Delay Dependent Stability ◽  
New Inequalities

This paper is concerned with the delay-dependent stability of systems with distributed time-varying delays. The novelty relies on the use of some new inequalities which are less conservative than some existing inequalities. A less conservative stability criterion is obtained by constructing some new augmented Lyapunov–Krasovskii functionals, which are given in terms of linear matrix inequalities. The effectiveness of the presented criterion is demonstrated by two numerical examples.

Study on the Characteristics of the Automatic Tracking of Multiple Target Tracking

2014 ◽  
Vol 496-500 ◽  
pp. 1564-1567
Author(s):  
Jing Feng He ◽  
Ming Ji ◽  
Song Cheng ◽  
Ya Nan Wang
Keyword(s):  
Target Tracking ◽  
Multiple Target Tracking ◽  
Multiple Target ◽  
Multiple Targets ◽  
Automatic Tracking ◽  
Single Target ◽  
Development Direction ◽  
The Future ◽  
Single Target Tracking

Based on introducing the traditional scan and single target tracking state, focuses on the automatic tracking characteristics of each stage under the condition of multiple targets. The two form of automatic tracking multiple targets, and the development direction of the future.

Asymptotic anti-synchronization of memristor-based BAM neural networks with probabilistic mixed time-varying delays and its application

2018 ◽  
Vol 32 (24) ◽  
pp. 1850287 ◽  
Author(s):  
Manman Yuan ◽  
Weiping Wang ◽  
Xiong Luo ◽  
Lixiang Li
Keyword(s):  
Neural Networks ◽  
Secure Communication ◽  
Time Varying ◽  
Bam Neural Networks ◽  
Bidirectional Associative Memory ◽  
Stochastic Variable ◽  
Numerical Examples ◽  
Synchronization Problem ◽  
Encryption And Decryption ◽  
Adaptive Laws

This paper is concerned with the asymptotic anti-synchronization problem of the memristor-based bidirectional associative memory neural networks (MBAMNNs) and its application in network secure communication. First, we propose a new model of MBAMNNs with probabilistic delays. By establishing a Bernoulli distributed stochastic variable, the information of transmittal time-varying delays is studied. Second, in order to provide a more robust and secure system, we develop a new anti-synchronization model based on the MBAMNNs. The adaptive laws are carefully designed to confirm the process of encryption and decryption in networks secure communication system. Finally, several numerical examples are presented to demonstrate the effectiveness and applicability of our proposed mechanism.

scholarly journals Effect of Herbal Medicinal Compounds on Alzheimer’s Disease Pathology in APP/PS1 Transgenic Mouse Model

2020 ◽  
Vol 15 (8) ◽  
pp. 1934578X2094898
Author(s):  
Xuexia Li ◽  
Zhijun He ◽  
Chao Wang ◽  
Yanjun Liu ◽  
Zhifu Shan ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Herbal Medicines ◽  
Protective Effects ◽  
Multiple Targets ◽  
Aβ Oligomers ◽  
Protein Levels ◽  
Medicinal Compounds ◽  
Single Target ◽  
Herbal Medicinal

The pathogenesis of Alzheimer’s disease (AD) is complex as various mechanisms interact with each other and, therefore, intervention from a single target is often ineffective. Many studies have shown that herbal medicines, such as curcumin, fisetin, icariin, and ginsenosides, have significant intervention effects on AD with different treatment mechanisms. Therefore, we have designed this study to know whether the combination of these herbal medicines can have an intervention effect on AD through multiple targets. Amyloid precursor protein/presenilin 1(APP/PS1) double transgenic AD mice were used to study the protective effects of a combination of curcumin, piperine, icariin, and ginsenosides, as well as a combination of fisetin, piperine, icariin, and ginsenosides, which were separately mixed into the feed. These herbal medicinal compounds (HMCs) lowered the serum lipid levels, reduced the Aβ oligomers, decreased the pS404-tau protein, as well as neurofibrillary tangles, and restored the reduction of synaptic protein levels and neuronal death of AD mice without causing toxicity to liver and kidneys. In this study, we found that HMCs have significant intervention against AD through multiple targets, providing a novel therapeutic idea for the prevention of AD.

scholarly journals Trends in excess mortality associated with atrial fibrillation over 45 years (Framingham Heart Study): community based cohort study

BMJ ◽  
2020 ◽  
pp. m2724
Author(s):  
Nicklas Vinter ◽  
Qiuxi Huang ◽  
Morten Fenger-Grøn ◽  
Lars Frost ◽  
Emelia J Benjamin ◽  
...  
Keyword(s):  
Atrial Fibrillation ◽  
Time Varying ◽  
Newly Diagnosed ◽  
Survival Times ◽  
Community Based ◽  
Period 2 ◽  
Hazard Ratios ◽  
Time Period ◽  
Heart Study ◽  
All Cause Mortality

AbstractObjectiveTo assess temporal trends in the association between newly diagnosed atrial fibrillation and death.DesignCommunity based cohort study.SettingFramingham Heart Study cohort, in 1972-85, 1986-2000, and 2001-15 (periods 1-3, respectively), in Framingham, MA, USA.ParticipantsParticipants with no atrial fibrillation, aged 45-95 in each time period, and identified with newly diagnosed atrial fibrillation (or atrial flutter) during each time period.Main outcome measuresThe main outcome was all cause mortality. Hazard ratios for the association between time varying atrial fibrillation and all cause mortality were calculated with adjustment for time varying confounding factors. The difference in restricted mean survival times, adjusted for confounders, between participants with atrial fibrillation and matched referents at 10 years after a diagnosis of atrial fibrillation was estimated. Meta-regression was used to test for linear trends in hazard ratios and restricted mean survival times over the different time periods.Results5671 participants were selected in time period 1, 6177 in period 2, and 6174 in period 3. Adjusted hazard ratios for all cause mortality between participants with and without atrial fibrillation were 1.9 (95% confidence interval 1.7 to 2.2) in time period 1, 1.4 (1.3 to 1.6) in period 2, and 1.7 (1.5 to 2.0) in period 3 (Ptrend=0.70). Ten years after diagnosis of atrial fibrillation, the adjusted difference in restricted mean survival times between participants with atrial fibrillation and matched referents decreased by 31%, from −2.9 years (95% confidence interval −3.2 to −2.5) in period 1, to −2.1 years (−2.4 to −1.8) in period 2, to −2.0 years (−2.3 to −1.7) in period 3 (Ptrend=0.03).ConclusionsNo evidence of a temporal trend in hazard ratios for the association between atrial fibrillation and all cause mortality was found. The mean number of life years lost to atrial fibrillation at 10 years had improved significantly, but a two year gap compared with individuals without atrial fibrillation still remained.

Compensation of Time-Varying Input and State Delays for Nonlinear Systems

2011 ◽  
Vol 134 (1) ◽  
Author(s):  
Nikolaos Bekiaris-Liberis ◽  
Miroslav Krstic
Keyword(s):  
Nonlinear Systems ◽  
Asymptotic Stability ◽  
Time Varying ◽  
Feedback Systems ◽  
Feedback Controllers ◽  
Stabilizing Controller ◽  
Numerical Examples ◽  
Infinite Dimensional ◽  
State Delays ◽  
Main Challenge

We consider general nonlinear systems with time-varying input and state delays for which we design predictor-based feedback controllers. Based on a time-varying infinite-dimensional backstepping transformation that we introduce, our controller achieves global asymptotic stability in the presence of a time-varying input delay, which is proved with the aid of a strict Lyapunov function that we construct. Then, we “backstep” one time-varying integrator and we design a globally stabilizing controller for nonlinear strict-feedback systems with time-varying delays on the virtual inputs. The main challenge in this case is the construction of the backstepping transformations since the predictors for different states use different prediction windows. Our designs are illustrated by three numerical examples, including unicycle stabilization.

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