15 November 2025, Volume 45 Issue 6
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Journal of Hangzhou Dianzi University. 2025, 45(6): 1-11. https://doi.org/10.13954/j.cnki.hdu.2025.06.001The coincidence detection of two surfaces is very important for a geometric modelling system, and directly affects the stability of the system. The corresponding key issue is to detect whether there exist bijective functions u=ρ1(s,t) and v=ρ2(s,t) for a coincident case. This paper presents and proves the existence of the corresponding two bijective functions ρ1(s,t) and ρ2(s,t) for overlapping of two non-degenerate bicubic surfaces. If they do not exist, the two surfaces do not overlap; if they exist, explicit formulas for the two bijective functions are provided to compute the overlapping region of the two surfaces. Numerical examples verify the efficiency and stability of the proposed method.
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Journal of Hangzhou Dianzi University. 2025, 45(6): 12-21. https://doi.org/10.13954/j.cnki.hdu.2025.06.002This paper presents a straightforward yet highly accurate method for establishing the parasitic structure model of microwave power Multi-cell Heterojunction Bipolar Transistor(HBTS). The proposed model is independent of a specific number of cells or the semiconductor material technology of the transistors, while it is closely related to the device's layout configuration. Utilizing S-parameter data measured under zero-bias conditions, the model is capable of precisely extracting component values from the equivalent circuit, with the extracted values being invariant to bias and power conditions, making it suitable for characterizing the impact of the external parasitic structures of Multi-cell HBTS under various biasing scenarios. Furthermore, this model can be integrated with the compact model of a single cell(unit cell) HBT to accurately represent the direct current(DC) and radio frequency(RF) operational characteristics of Multi-cell HBTS. The applicability and accuracy of the proposed model have been validated using a 6 cell Gallium Arsenide(GaAs) HBT device as a test subject.
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Journal of Hangzhou Dianzi University. 2025, 45(6): 22-30. https://doi.org/10.13954/j.cnki.hdu.2025.06.003Product quantization, as an efficient high-dimensional vector data compression technique, is widely applied in the field of approximate nearest neighbor search. However, its existing non-uniform bit allocation methods struggle to adapt to complex real-world data distributions due to a lack of theoretical support. To address this, a theoretical solution to the non-uniform bit allocation problem has been derived from the rate-distortion theorem in information theory, and a bit allocation model adaptable to the information content of the subspaces has been proposed. This model consists of three parts: subspace information calculation, bit weight generation, and bit number optimization, aiming at enhancing the precision and generalization capability of quantization. Furthermore, to improve the search performance after quantization, an optimized subspace pruning algorithm has been designed. This algorithm precomputes the minimum distance of subspaces to filter out a significant number of non-neighbor vectors, effectively resolving the pruning failure issue caused by short sums of space distances. Experimental results on multiple real-world datasets indicate that the proposed method has achieved a nearly 30% improvement in search accuracy and nearly a 2.8-fold increase in query efficiency.
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Journal of Hangzhou Dianzi University. 2025, 45(6): 31-38. https://doi.org/10.13954/j.cnki.hdu.2025.06.004Based on the 2 μm GaAs HBT process of WIN, a wideband, high output power, low phase noise, and continuously tuned Clapp Voltage-Controlled Oscillator(VCO) is designed. By setting up dual varactor diodes as tuning devices, the narrow bandwidth limitation of conventional Clapp oscillators is alleviated. And a method is proposed to expand the bandwidth by connecting ground capacitors in parallel at the outputs. The layout EM simulation results show that the output frequency range of the voltage-controlled oscillator is 5.88~12.15 GHz, the phase noise is -115.611~-119.142 dBc/Hz@1 MHz, the output frequency range is 256-4.51 dBm, the chip area is 2.13 mm2, the power consumption is 198.5 mW, the figure of merit(FOM) is -171.675 dBc/Hz and the figure of merit normalized to tuning range(FOMT) is -188.521 dBc/Hz.
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Design of high stability temperature control system for atomic cell of punctual-type Rb atomic clockJournal of Hangzhou Dianzi University. 2025, 45(6): 39-48. https://doi.org/10.13954/j.cnki.hdu.2025.06.005The high precision temperature control of the Rb atomic cell is a key technology for the punctuality of the Rb atomic clock. Continuously improving the temperature control accuracy and response speed of the atomic cell is the key to affect the punctuality of the Rb atomic clock in different field application environments. To address this problem, this paper proposes a high precision, high stability temperature control system. In this system, environmental correction variables are introduced into fuzzy PID controller to improve the ability of resisting environmental temperature disturbance. The Matlab simulation experiments verify that the improved fuzzy PID algorithm used in this system have better control effect than the PID algorithm. Experimental results show that the system has good temperature resistance performance, the control accuracy reaches 0.1 ℃, and the temperature stability is improved by more than 50% compared with the conventional control algorithm. It provides a feasible performance improvement scheme for the temperature control system of the atomic cell of the punctured Rb atomic clock.
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Journal of Hangzhou Dianzi University. 2025, 45(6): 49-59. https://doi.org/10.13954/j.cnki.hdu.2025.06.006This paper aims to report an algorithm capable of automatically segmenting and evaluating calcified areas and to perform an automatic analysis of rib cartilage calcification based on existing datasets. In this paper, we proposed an automatic segmentation algorithm for calcified rib cartilage regions in computed tomographic(CT) images, a watershed algorithm based on automatic marking of skeletal lines, and an automatic extraction algorithm for images of the 6th, 7th, and 8th costal cartilages to automatically analyze the calcification of rib cartilage at different ages, and the performance of this method is verified through experiments. It is found that the calcification rate decreased with increasing rib cartilage order. There are significant differences in the degree of calcification between costal cartilages of different ordinal numbers. The automatic segmentation of calcified rib cartilage and the automatic extraction of the 6th, 7th and 8th costal cartilages based on the segmentation results proposed in this paper are generally effective, and any number of datasets can be analyzed with this automated approach. The algorithm currently produces some errors in the segmentation stage, mainly due to the small size of the dataset used for training the model.
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Journal of Hangzhou Dianzi University. 2025, 45(6): 60-68. https://doi.org/10.13954/j.cnki.hdu.2025.06.007The formation and dispersion uniformity of monodisperse droplets are crucial for the effective atomization and combustion of liquid fuels. The dispersion uniformity of single droplets is possibly affected by the physical properties of liquid fuels. This paper focuses on the two-component fuel of n-decane and isopropanol, and measures their physical parameters such as density, viscosity, and surface tension coefficient at different isopropanol component contents. Moreover, the formation and dispersion performance are further estimated. The results show that as the content of isopropanol increases, the density of the two-component fuel increases linearly. The viscosity coefficient has an overall upward trend and conforms to a quadratic relationship with the content of isopropanol. The surface tension coefficient shows a trend of first decreasing and then increasing, and follows a polynomial relationship with the content of isopropanol. The particle size of producing monodisperse droplets deteriorates with increasing the isopropanol content. The driving frequency of piezoelectric actuator has a significant impact on the size distribution of single droplets. As the driving frequency increases, the average droplet size decreases. Uniform monodisperse droplets can be generated through piezoelectric driving, and adjusting the driving frequency can effectively regulate the average particle size and uniformity of single droplets.
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Journal of Hangzhou Dianzi University. 2025, 45(6): 69-76. https://doi.org/10.13954/j.cnki.hdu.2025.06.008The anodic oxide film was prepared on the surface of ZL102 aluminum alloy with sulfuric acid, sulfuric acid-oxalic acid, sulfuric acid-tartaric acid and sulfuric acid-citric acid. The effect of organic acid with the same molar concentration on the properties of the film was investigated. The surface morphology of the oxide film was observed by metallographic microscope and the porosity ratio was obtained by using cell counting method. The thickness of the film was measured by eddy current method and verified by metallographic method. The mechanical properties of ZL102 aluminum alloy before and after anodizing were tested by Wechsler hardness test. The electrical properties of the film were tested by withstand voltage resistance test. The thermal properties before and after anodic oxidation were tested by thermal conductivity test. The results show that the uniform color and smooth surface oxide films of ZL102 aluminum alloy can be obtained in all of the four systems, and the anodic oxide film formed in sulfuric acid-oxalic acid is the thickest, up to 27.5 μm. The addition of organic acids can reduce the porosity, and oxalic acid achieves the best effect. The anodic oxidation hardness of each system is basically the same, more than 45%. In the case of unsealed holes, the point withstand voltage of anodic oxidation of each system is more than 1.5 kV, and the highest voltage of sulfuric acid-oxalic acid system is up to 1.698 kV. The diameter of 10 mm single-side voltage is more than 0.5 kV, the highest in sulfuric acid, up to 0.777 kV. The anodic oxidation of each system increased the thermal resistance by more than 64%, which reduced the thermal conductivity, but the addition of organic acids helped to reduce the thermal resistance. In summary, the comprehensive properties of ZL102 aluminum alloy were better in the solution system with oxalic acid added to sulfuric acid.
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Journal of Hangzhou Dianzi University. 2025, 45(6): 77-86. https://doi.org/10.13954/j.cnki.hdu.2025.06.009Satellite timing is crucial in various fields, including power electronics technology. However, the single-frequency receivers in current widespread use either lack timing functions or have low accuracy. To address these needs,this paper proposes a high-precision time generation method suitable for single-frequency receivers. This method increases the number of effective observation satellites by combining the BDS-3 and GPS dual systems. Carrier phase information is introduced based on Hatch filtering to reconstruct the pseudorange observation values. Utilizing the satellite common view method principle, the inter-station single difference algorithm calibrates the output time, aligning the single-frequency receiver with the high-precision time and frequency standards of the reference station. Experimental verification shows that the accuracy of the 1PPS output can reach nanoseconds after calibration, with system variance remaining stable at approximately 1 ns over a kilosecond period.
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Journal of Hangzhou Dianzi University. 2025, 45(6): 87-93. https://doi.org/10.13954/j.cnki.hdu.2025.06.010In this paper, the mutual information between subsystems in three-qubit systems was studied. An inequality relating to the mutual information between two subsystems was obtained. Meanwhile, it also studied the monogamy relation of quantum mutual information, and found three kinds of quantum states which satisfy a stricter monogamy relation.
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Journal of Hangzhou Dianzi University. 2025, 45(6): 94-100. https://doi.org/10.13954/j.cnki.hdu.2025.06.011The Korteweg-de Vries(KdV) equation is a nonlinear partial differential equation that describes the propagation of water waves and has a Hamiltonian form. An energy conservation finite element method is proposed for a KdV equation. By introducing two auxiliary variables, the KdV equation is reformulated into an equivalent lower-order coupled system, which can be solved in the space H1(Ω) instead of H3(Ω) required by the original equation. For the new system, finite element method and second-order Crank-Nicolson scheme are used for spatial and temporal discretization respectively. The energy conservation properties of semi-discrete and fully discrete schemes are proved, and the optimal error estimation of the discrete scheme is analyzed in a linear case. Finally, the energy conservation and error convergence are verified through numerical experiments.
