11 results on '"Hu, Zhipei"'
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2. Synchronization of Complex Dynamical Networks Subject to Noisy Sampling Interval and Packet Loss.
- Author
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Hu, Zhipei, Ren, Hongru, and Shi, Peng
- Subjects
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SYNCHRONIZATION , *STOCHASTIC analysis , *DISTRIBUTION (Probability theory) , *NOISE measurement , *SAMPLING errors - Abstract
This article focuses on the sampled-data synchronization issue for a class of complex dynamical networks (CDNs) subject to noisy sampling intervals and successive packet losses. The sampling intervals are subject to noisy perturbations, and categorical distribution is used to characterize the sampling errors of noisy sampling intervals. By means of the input delay approach, the CDN under consideration is first converted into a delay system with delayed input subject to dual randomness and probability distribution characteristic. To verify the probability distribution characteristic of the delayed input, a novel characterization method is proposed, which is not the same as that of some existing literature. Based on this, a unified framework is then established. By recurring to the techniques of stochastic analysis, a probability-distribution-dependent controller is designed to guarantee the mean-square exponential synchronization of the error dynamical network. Subsequently, a special model is considered where only the lower and upper bounds of delayed input are utilized. Finally, to verify the analysis results and testify the effectiveness and superiority of the designed synchronization algorithm, a numerical example and an example using Chua’s circuit are given. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
3. Stabilization of Sampled-Data Systems With Noisy Sampling Intervals and Packet Dropouts via a Discrete-Time Approach.
- Author
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Hu, Zhipei, Ren, Hongru, Deng, Feiqi, and Li, Hongyi
- Subjects
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DISCRETE-time systems , *DISTRIBUTION (Probability theory) , *VANDERMONDE matrices , *STOCHASTIC systems , *KRONECKER products , *DATA packeting - Abstract
In real-world applications, sampled-data systems are often subject to undesirable physical constraints, which results in noisy sampling intervals that fluctuate around an ideal sampling period based on certain probability distribution. In the presence of noisy sampling intervals, this article is concerned with the stabilization problem for a class of sampled-data systems with successive packet dropouts. First, the relationship between two adjacent update times of zero-order hold is established. Then, by discrete-time approach, an equivalent discrete-time stochastic system is introduced. By the law of total expectation, together with confluent Vandermonde matrix, convolution formula, and Kronecker product operation, the mathematical expectation of a product of three matrices, including the system matrix and its transpose, is calculated. Based on this, a stabilization controller is designed such that the closed-loop system is stochastically stable. Finally, an illustrative example is provided to verify the effectiveness of the proposed design approach. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
4. A discretization approach to sampled‐data stabilization of networked systems with successive packet losses.
- Author
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Hu, Zhipei, Zhang, Jin, Deng, Feiqi, Fan, Zhun, and Qiu, Li
- Subjects
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STOCHASTIC systems , *DISCRETE-time systems , *EXPONENTIAL stability , *STABILITY criterion , *MATRIX functions , *STOCHASTIC matrices - Abstract
This article is concerned with the stabilization problem for a class of networked systems subject to successive packet losses. Different from the input delay approach used in some existing literature, the continuous‐time system under consideration is first converted into a discrete‐time stochastic system with system matrices subject to stochastic characteristic. In order to deal with the difficulties in the calculations of mathematical expectations of both matrix exponential and integral of matrix exponential function, the upper bound of successive packet losses and packet drop rate are assumed to be known and then the probabilities of the number of successive packet losses taking each value in a bounded set are calculated. Based on this, stability criteria are derived by recurring to the law of total expectation, which guarantee the exponential mean‐square stability of resulting closed‐loop discrete‐time stochastic system with a prescribed H∞ performance. Moreover, a controller design procedure is then proposed. Finally, to verify the analysis results and testify the effectiveness and applicability of the designed algorithm, a numerical simulation example is given. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
5. Numerical simulation of fin arrangements on the melting process of PCM in a rectangular unit.
- Author
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Hu, Zhipei, Jiang, Shuo, Sun, Zhigao, and Li, Jun
- Subjects
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HEAT storage , *FINS (Engineering) , *NATURAL heat convection , *MELTING , *COMPUTER simulation - Abstract
Innovative fin arrangements were proposed to enhance the thermal performance of latent heat storage units. The enthalpy-porosity approach was employed to optimize the fin distribution and predict the transient melting behaviors of N-octadecane. The unit with horizontal fins of uniform length was set as the base condition for comparison. It was found that the dead space of heat transfer and melting due to natural convection was not effectively eliminated by the conventional fin set. The region persisted at the bottom of the unit until the end of the melting process. In light of these observations, the fins were repositioned and resized. Three alternative fin configurations were proposed and evaluated: angled fins, asymmetrically located fins, and stepped fins. Results illustrated that fin structures significantly influenced the heat transfer characteristics and melting behaviors of latent heat storage units. Generally, greater enhancements were attained with downward angles and downward offset distances. The downward angle −20°led to an accelerated melting rate of 18.3 % compared to the base condition. In case 9, where the fins were moved down by 12 mm, the heat transfer enhancement ratio reached 32.5 %. However, introducing inhomogeneity in the fin length had only a minimal impact on the melting process. • Non-uniformity in heat transfer due to natural convection decreases the overall PCM melting. • Novel fin arrangements are employed in this paper to improve the PCM melting as well as heat transfer. • Fins with downward angle and downward offset can substantially increase the thermal energy storage rate. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
6. Security control of networked systems with deception attacks and packet dropouts: A discrete-time approach.
- Author
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Hu, Zhipei, Deng, Feiqi, Su, Yongkang, Zhang, Jin, and Hu, Songlin
- Subjects
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DECEPTION , *STOCHASTIC systems , *DISCRETE-time systems , *GRIDS (Cartography) , *ELECTRIC power distribution grids - Abstract
This paper is concerned with the security control problem for a class of networked systems subject to deception attacks and packet dropouts. First, by taking into account the deception attacks and packet dropouts in an unified framework, a discrete-time stochastic system is presented. In virtue of matrix exponential computation, an equivalent discrete-time stochastic model is established. Based on this, the security analysis is given by the law of total expectation and some sufficient conditions are provided. Subsequently, a controller is designed. Finally, the effectiveness of the proposed method is illustrated by two examples including a practical power grid system. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
7. Saturated H∞ control of networked systems under stochastic transmission delays: The random sampling periods case.
- Author
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Chen, Kai, Song, Haiyu, Hu, Zhipei, and Deng, Feiqi
- Subjects
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STOCHASTIC systems , *MATRIX exponential , *LINEAR matrix inequalities , *VANDERMONDE matrices , *KRONECKER products , *STATISTICAL sampling , *MARKOVIAN jump linear systems - Abstract
In this paper, the H∞$$ {H}_{\infty } $$ saturated control problems of networked systems with random sampling periods and stochastic transmission delays are investigated. The main issue is to design an H∞$$ {H}_{\infty } $$ saturated controller such that the controlled close‐loop system is exponentially mean‐square stable with a desired H∞$$ {H}_{\infty } $$ performance. A matrix exponential which is different from some existing literature is used to reconstruct the discrete‐time stochastic system to an equivalent yet tractable augmented model without any additional conditional constraint. In virtue of reduced‐order confluent Vandermonde matrix approach and Kronecker product operation, the stability condition in terms of linear matrix inequality is derived and then the desired H∞$$ {H}_{\infty } $$ saturated controller is designed. It should be emphasized that the improved method can also be used for the stability analysis and controller design when the system matrix contains complex roots. Finally, two numerical examples and a three‐axis milling machine system are utilized to manifest the reliability and practicality of the designed strategy. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
8. Stabilization of networked systems with communication constraints: The random sampling periods case.
- Author
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Hu, Zhipei and Su, Yongkang
- Subjects
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TELECOMMUNICATION systems , *MATRIX exponential , *DISTRIBUTION (Probability theory) , *STOCHASTIC systems , *VANDERMONDE matrices , *STATISTICAL sampling , *DISCRETE-time systems - Abstract
In this paper, the stabilization problem of networked systems with communication constraints is studied, where the random sampling periods, deception attacks and packet losses are considered simultaneously. Different from the existing literature, the actual sampling periods are subject to undesirable physical constraints and fluctuate around an ideal sampling period with certain probability distribution. First, a closed-loop discrete-time stochastic system is constructed by considering the random sampling periods, deception attacks and packet losses in a unified framework. Second, an equivalent yet tractable stochastic model is established with the aid of matrix exponential computation. By reduced-order confluent Vandermonde matrix approach, law of total expectation, convolution formula and Kronecker product operation, a controller is designed such that the exponential stability in the mean-square sense of closed-loop stochastic system is guaranteed. Subsequently, a special model is discussed where no deception attack occurs and then the corresponding controller is designed. Finally, an illustrative example is given to show the effectiveness of the designed approach. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
9. Stability and guaranteed cost control for linear impulsive systems with random impulses: Application to stochastic event‐triggered control.
- Author
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Luo, Shixian, Zhong, Qinghua, Jiang, Yan, Deng, Feiqi, and Hu, Zhipei
- Subjects
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LINEAR control systems , *COST control , *DISCRETE-time systems , *MONTE Carlo method , *STABILITY criterion , *IMPULSIVE differential equations , *HOPFIELD networks - Abstract
Summary: This paper proposes a systematic framework for stability and guaranteed cost control of linear impulsive systems subject to random time‐ and event‐triggering impulses. Moment stability criteria and design methods of time‐ and event‐triggered controllers with guaranteed quadratic performance for the impulsive system are established. It shows that the proposed event‐triggered controller in the sense that it guarantees at least the same quadratic performance function bound as the designed time‐triggered guaranteed cost controller, however, with a larger, or at most equal, average inter‐transmission time. Based on the proposed framework of random‐impulses systems, a stochastic dynamic event‐triggered control strategy is proposed to solve sampled‐data control systems in the presents of sporadic measurements or stochastic sampling. Numerical simulations illustrate the effectiveness of the proposed theoretical results. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
10. Experimental study on thermal performance of high absorption latent heat storage plate (LHSP) in greenhouse.
- Author
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Meng, Erlin, Zhao, Junpeng, Tian, Ruian, Hu, Zhipei, Li, Jun, Zhou, Bo, Wang, Chenyang, and Zhao, Haiqian
- Subjects
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HEAT storage , *HEAT radiation & absorption , *LATENT heat , *PHASE change materials , *GREENHOUSES - Abstract
Phase change material (PCM) can effectively reduce temperature fluctuations in greenhouses and increase crop yields. Plastic greenhouses are a major form of facility agriculture in southern China, and there are no walls in it. Therefore, how to combine plastic greenhouses with PCM has become research hotspot. A new type of high absorption latent heat storage plate (LHSP) was proposed. That is to lay PCM plates on the north side of the plastic greenhouse vertically. To enhance solar energy utilization and reduce heat loss, solar high absorption and thermal insulation layer were respectively placed on the sunny side and shady side. Two greenhouses were constructed and LHSP was placed in one greenhouse as Case 1. After that, a solar high absorption film and thermal insulation layer were attached to the sunny side and the shady side as Case 2 and Case 3. The average air temperature of two greenhouses and the thermal performance of LHSP were compared under three cases. Results showed that, in Case 1, the LHSP can raise the average air temperature inside the greenhouse by 1.8–2.9 °C during the night. in Case 2 and 3, the average air temperature had a stable improvement of 1.6–2.2 °C and 1.8–2.1 °C respectively at night. Besides, in Case 2, the heat storage of LHSP on sunny side had increased by 26.2%. In Case 3, the total average heat loss of LHSP was reduced by 21.5% and the average heat release from sunny side had risen by up to 39.7%. The high absorption latent heat storage plate showed excellent thermal performance. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
11. Strategies for promoting the degradation of phenol by electro-Fenton: Simultaneously promoting the generation and utilization of H2O2.
- Author
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Zhang, Zhuangzhuang, Zhao, Haiqian, Wang, Zhonghua, Hu, Zhipei, Wang, Qingshu, Meng, Erlin, Lai, Shiwei, Ying, Jiaxin, Li, Hongguang, and Wu, Chuanyan
- Subjects
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PHENOL , *ACTIVATED carbon , *POLLUTANTS , *DENSITY functional theory - Abstract
The use of the electro-Fenton process to continuously generate H 2 O 2 and efficiently degrade organic pollutants is considered a promising technology. The ratio of generation of H 2 O 2 is usually regarded as the critical step; however, how the H 2 O 2 is utilized is also of particular importance. Herein, activated carbon was activated at different temperatures and used to explore the effect of nitrogen doping on the production and utilization of H 2 O 2 in the electro-Fenton-based degradation of organic pollutants. The experimental results indicate that nitrogen-doped activated carbon simultaneously promotes the generation and utilization of H 2 O 2 , which is attributed to the regulation of the competition between phenol and O 2 adsorption by the doped nitrogen. Nitrogen doping not only improves 2e−ORR selectivity but also aggregates phenol near the cathode to balance the concentrations of phenol and ·OH. Density functional theory (DFT) calculations further confirmed that pyrrole-N as a dopant promoted the adsorption of phenol, while pyridine-N was more favorable for O 2 adsorption. The unique balance of nitrogen types possessed by modified activated carbon NAC-750 permits the efficient synergistic generation and utilization of H 2 O 2 in a balanced manner during the degradation of phenol. This work provides a new direction for the rational nitrogen-doping modification of activated carbon for the electro-Fenton-based degradation of organic pollutants. [Display omitted] • The adsorption of phenol affects the adsorption of O 2 and the generation of H 2 O 2. • Graphite-N is the main site for the competitive adsorption of phenol and O 2. • Competition can be effectively regulated by regulating nitrogen doping types. • Reasonable nitrogen doping can promote the generation and utilization of H 2 O 2. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
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