15 May 2025, Volume 45 Issue 3
-
Select all|
-
Journal of Hangzhou Dianzi University. 2025, 45(3): 1-7. https://doi.org/10.13954/j.cnki.hdu.2025.03.001Based on the weak signal processing requirements of silicon carbide (SiC) high-performance neutron detection system, a low-noise and low-power SiC neutron detector readout circuit is designed. The readout circuit reads, shapes and amplifies the weak signal output by the SiC neutron detector, and forms a neutron detection system with the front-end detector and the back-end counter, which can realize the needs of neutron count measurement. The designed readout circuit integrates a low-voltage power management module, preamplifier, main amplifier and discriminator. In order to verify the effectiveness of the circuit design, the readout circuit is experimentally tested. The test results indicate that the single board power consumption is about 300 mW, the equivalent input noise is about 1 fC, where the preamplifier linearity is 99.72%, the output dynamic range is about ±3 V, and the total amplification block gain is about 19.28 mV/fC. The designed circuit has the characteristics of low noise, low power consumption, high gain and good stability.
-
Journal of Hangzhou Dianzi University. 2025, 45(3): 8-15. https://doi.org/10.13954/j.cnki.hdu.2025.03.002In this paper, a low noise amplifier (LNA) circuit with an operating frequency of 4～8 GHz is developed. A lossy matching network is used to achieve the broadband characteristics and in-band flatness of the LNA, both gain and noise performance of the LNA are taken into account by reasonably distributing the gain of the two stages. The LNA is implemented by a localized GaAs pHEMT process, and the measurement results show that the gain is 20.5 dB, the input return loss is better than 14 dB, and the output return loss is better than 12 dB in the operating frequency band.Based on the wafer-level heterogeneous packaging process, the package design for this LNA was developed, and a co-simulation method integrating wafer-level packaging process with GaAs process was proposed to evaluate the performance of the packaged LNA.The proposed co-simulation method provides a reference for building heterogeneous microsystems based on wafer-level processes and microwave solid-state integrated circuits.
-
Journal of Hangzhou Dianzi University. 2025, 45(3): 16-22. https://doi.org/10.13954/j.cnki.hdu.2025.03.003Based on the requirement of dual frequency high-power microwave combination, a scheme of dual frequency TE01 mode combiner was designed. Firstly, a filter operating in two frequency bands was designed adopting an overmoded circular waveguide. Then, a six channel rectangular waveguide arranged axially on the waveguide sidewall was used to achieve the merging of two TE01 mode filters. The merging part was a linear circular waveguide structure, ensuring the merging effect of TE01 mode signals in both frequency bands. To verify the effectiveness of the proposed scheme, two TE01 mode filters were designed with center frequencies of 9.4 GHz and 9.63 GHz, respectively. Then the two TE01 mode filters were combined using the scheme described in this article. According to the numerical simulated results, at the center frequencies of 9.3 GHz and 9.7 GHz, the bandwidths with transmission efficiency better than 98% are 86 MHz and 88 MHz, respectively, and the power capacity is greater than 2 GW. The design of this article provides a solution for high-power dual frequency transmission systems.
-
Journal of Hangzhou Dianzi University. 2025, 45(3): 23-28. https://doi.org/10.13954/j.cnki.hdu.2025.03.004The input-to-state stability control of interval type-2 fuzzy system with parameter uncertainties under denial-of-service attack is studied. Firstly, based on the characteristics of denial-of-service attack and inspired by zero-order hold, a fuzzy state feedback controller is designed; secondly, a suitable Lyapunov function is selected, and based on the idea of controlling the error within a boundary value, the sufficient conditions for the input-to-state stability control of the system are derived by using methods such as inequality contraction; finally, a numerical simulation explains the validity of the result.
-
Journal of Hangzhou Dianzi University. 2025, 45(3): 29-41. https://doi.org/10.13954/j.cnki.hdu.2025.03.005This paper mainly studied the vehicle platooning control problem based on adaptive event-triggered undersemi-Markov switching topologies.Firstly, the dynamic model of a single vehicle in the presence of unknown external disturbances was constructed. In order to describe the time-varying characteristics of the communication topology between vehicles, a semi-Markov random process was used to characterize it. Then, in order to reduce the burden of communication, a novel adaptive event-triggered mechanism was adopted to reduce the frequency of data transmission. Furthermore, mixed H∞/passive performance index was also considered in the controller design, which could make the control system more robust against disturbance. The control goal in this paper was to design a controller for each following vehicle so that it can track the pilot vehicle. In order to achieve this goal, the relevant error signal was defined and the closed-loop system of the vehicle platooning was established, and the controller design algorithm was obtained based on Lyapunov stability theory. Finally, simulation examples are presented to verify the feasibility of the proposed approach.
-
Journal of Hangzhou Dianzi University. 2025, 45(3): 42-49. https://doi.org/10.13954/j.cnki.hdu.2025.03.006The existing ubiquitous storage system uses erasure code technology to ensure the reliability of data, but the differences of nodes in bandwidth, computing power, storage resources, etc. will adversely affect the data restoration of erasure code. To solve the problem of selecting supply nodes in the process of data restoration, an adaptive node selection strategy is proposed. The actual computing power of nodes is dynamically adjusted according to the changes of node load, and the optimal supply nodes are selected based on the changes of network distance and node load to participate in data restoration, so as to improve the repair efficiency. Simulation results show that the proposed algorithm can reduce the repair delay.
-
Journal of Hangzhou Dianzi University. 2025, 45(3): 50-62. https://doi.org/10.13954/j.cnki.hdu.2025.03.007Aiming at the problemof excessive computational load in commonly used neural network classification models, this paper proposes a lightweight Convolutional Neural Network model that can be deployed in low-end embedded devices-a lightweight convolutional neural network model based on MobileNet and ShuffleNet. This model combines the characteristics of MobileNet and ShuffleNet, introduces Squeeze-and-Excitation channel attention mechanism and shortcut branch, and uses improved h-swish activation function to replace the original ReLU activation function, so as to improve both the recognition accuracy and the computational efficiency. Test results verify that the proposed lightweight convolutional neural network model based on MobileNet and ShuffleNet outperforms traditional lightweight convolutional neural network models such as MobileNet, ShuffleNet, EfficientNet, etc.
-
Journal of Hangzhou Dianzi University. 2025, 45(3): 63-72. https://doi.org/10.13954/j.cnki.hdu.2025.03.008Methane (CH4) is an important greenhouse gas, and it is critical to investigate the mechanisms of CH4 microleakage and thus to evaluate the atmospheric CH4 sources and sinks. This paper reviews the research progress on CH4 migration mechanisms in underground porous medium and focuses on the application of Computational Fluid Dynamics (CFD) in this field. The physical properties of underground porous medium are complex and diverse, and the CH4 microleakage process is affected by multiple factors. Diffusion, convection and buoyancy have influences on CH4 migration, but the dominant mechanism is still controversial. As CFD technique is easy to quantitatively control, has predictive functions, and can make up for the limitations of field monitoring and experimental physical simulation, it has been widely applied to the research of CH4 migration mechanisms in various underground porous medium conditions. This paper summarizes the application of CFD technique in the modeling of CH4 migration process in the scenarios of buried natural gas pipeline leakage, coal bed methane, shale gas, landfill gas and seabed gas hydrate exploitation, and identifies the main mechanisms and influencing factors of CH4 migration. This paper will provide a reference for the application of CFD technique in the research of microleakage CH4 migration mechanisms of underground oil and gas reservoirs.
-
Journal of Hangzhou Dianzi University. 2025, 45(3): 73-75. https://doi.org/10.13954/j.cnki.hdu.2025.03.009There is a close relationship between quantum covariance and quantum Fisher information, and the covariance matrix and quantum Fisher information matrix satisfy a matrix inequality. This paper aims to generalize this matrix inequality by using tools such as operator monotone functions.
-
Journal of Hangzhou Dianzi University. 2025, 45(3): 76-83. https://doi.org/10.13954/j.cnki.hdu.2025.03.010In this paper, we study the global existence problem of solutions to three-dimensional incompressible magnetohydrodynamic equations in whole space R3 with a class of initial data which slowly varies in the vertical variable. We aim to investigate the existence of large solutions to the magnetohydrodynamic equations in critical space. In the present work, we introduce the critical anisotropic Besov space which is based on Littlewood-Paley decomposition, and prove that there exists a unique global solution to the incompressible magnetohydrodynamic equations with such initial data.
-
Journal of Hangzhou Dianzi University. 2025, 45(3): 84-88. https://doi.org/10.13954/j.cnki.hdu.2025.03.011Based on third-ordes tensor singular value decomposition, frequent directions and sparse subspace embedding technique, a new algorithm is designed to solve low tubal-rank approximations of third-order tensors. The use of frequent directions improves the approximation accuracy, while sparse subspace embedding improves the computational efficiency of the algorithm. Experimental results on color images and synthetic datasets show higher accuracy and speed in comparison with prevailing tensor low-rank approximation algorithms.
-
Journal of Hangzhou Dianzi University. 2025, 45(3): 89-94. https://doi.org/10.13954/j.cnki.hdu.2025.03.012Support tensor machine model is a high-order extension of support vector machine. It has gained much attention for its capability of directly handling the classification of tensor data, and has been widely applied in areas such as image processing, video analysis, and machine learning. Traditional support tensor machines use a hinge loss function that is non-smooth, making it difficult to design the corresponding algorithm and solve the model. To overcome this limitation, this paper combines with Tensor Train decomposition, and proposes a class of support tensor machines based on the Huber loss function. An alternating direction method of multipliers is designed for solving the proposed models. Specific expressions for solving each subproblem are provided, the effectiveness of the model and the algorithm is validated through numerical experiments.
-
Journal of Hangzhou Dianzi University. 2025, 45(3): 95-102. https://doi.org/10.13954/j.cnki.hdu.2025.03.013A new nonconvex and nonsmooth variational model based on local information is proposed for the segmentation of images with intensity inhomogeneity, as the nonconvex variational method has the advantage of preserving edges of the image. The nonconvex regularization term defined in the model can effectively preserve the edge information of the image, and a kernel function is defined in the data fitting term for extracting the local intensity information of the image. By using the alternating update strategy, the proposed model can be decomposed into two subproblems, and each subproblem can be effectively solved. Experimental results show that the proposed model has good segmentation performance for both synthetic and real images.
