bob手机在线登陆学报自然版

2021, 41(10): .

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2021, 41(10): .

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Key Technologies of Virtual Monitoring Driven by Distributed Real-Time Running Data for Hydraulic Support Group

LI Juanli, LI Menghui, XIE Jiacheng, WANG Xuewen, ZHANG Xin

2021, 41(10): 1023-1033. doi:10.15918/j.tbit1001-0645.2020.191

Abstract(763) PDF(438)

Abstract:
To solve the problems of data quantity in visual monitoring for multi-machine equipment and some irresolvable complex tasks in single host model, a virtual monitoring method driven by real-time running data was proposed for a distributed hydraulic support group. Firstly, a driving model was established based on real-time running data. According to a data transfer method of identifiable data interactors, a distributed local area network collaboration model was established under C/S mode. And then, based on an allocation method of monitoring tasks with consistent Hash algorithm, a task scheduling model was established to dynamically allocate tasks according to the host load status. Finally, taking the laboratory hydraulic support group as the experimental object, a distributed virtual monitoring system was constructed. The experimental results show that, compared with the system established with a single host, the monitoring system established by this method can greatly improve the stability of monitoring and can provide core technical support for the construction of transparent fully mechanized mining face.

Research on Controllability of Active Hydrostatic Journal Bearing with Pressure Control Cavity

CHEN Shujiang, SUN Jiaheng

2021, 41(10): 1034-1042. doi:10.15918/j.tbit1001-0645.2021.014

Abstract(649) PDF(312)

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To improve the controllability and stability of the active hydrostatic spindle,a smaller control-cavitywas nested in each oil cavity of the traditional hydrostatic bearing, and the active single-side membrane restrictor was used to supply oil to it.The two-time throttling inside the bearing was fully utilized to realize excellent controll ability of hydrostatic bearing. Based on the Reynolds lubrication equation and the flow conservation equation, the dynamic axis orbit model of the hydrostatic spindle was established by the finite difference method and the Euler iteration method and the dynamic characteristics and control characteristics of the bearing under different bearing structures and oil supply pressures were theoretically studied. The results indicate that the hydrostatic bearing has both better dynamic characteristics and control characteristics while the width of the bearing land is 5 mm and the area ratio of the control-cavity is 30%.The well-designed hydrostatic bearing nested with control-cavity can improve the controll ability of hydrostatic spindle movement.

Influence of Submerged Depths on the Modal Parameters of a Centrifugal Impeller

ZENG Yongshun, LIU Yanqi, DENG Liuhong, LIU Lanlin, YAO Zhifeng, XIAO Ruofu

2021, 41(10): 1043-1049. doi:10.15918/j.tbit1001-0645.2021.019

Abstract(594) PDF(309)

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The vibration of the centrifugal impeller and its amplitude are affected by the added mass and damping of the surrounding water. In order to clarify the influence of different submerged depths on dynamic response characteristics of the centrifugal impeller, numerical and experimental studies were carried out. The modal analysis of the impeller under air and different submerged depth conditions were carried out based on coupled acoustic fluid-structure method. The response parameter of the impeller structure in air and in different submerged depth conditions were obtained through hammering method, and then the numerical prediction accuracy of natural frequency was evaluated. Based on simulation and experimental results, the variation laws of mode shape, added mass and damping ratio with different submerged depths were constructed. The results show that the mode shape does not change as the submerged depth increases. However, the added mass and damping coefficients of the impeller increase linearly with the increase of the relative submerged depth. If the impeller is fully submerged, the added mass and hydrodynamic damping ratio are 0.39 times and 1.76 times of those in air, respectively.

Coordinated Control of Front-Wheel Steering Angle and Yaw Stability for Unmanned Ground Vehicle Based on State Estimation

CHEN Te, XU Xing, CAI Yingfeng, CHEN Long, SUN Xiaoqiang

2021, 41(10): 1050-1057. doi:10.15918/j.tbit1001-0645.2020.071

Abstract(603) PDF(326)

Abstract:
Aiming at the trajectory tracking problem of unmanned vehicle, a coordinated control strategy of front-wheel steering angle and yaw stability was proposed for unmanned vehicle based on state estimation. Firstly, a vehicle trajectory tracking model was established, and a trajectory tracking controller was designed with the model predictive control algorithm to obtain the front-wheel steering angle required of tracking reference trajectory in real time. And then, according to the vehicle model, a method of front-wheel steering angle estimation based on unknown input observer was designed and the estimation result was used as the input of front-wheel steering angle tracking control. Based on the nonsingular terminal sliding mode control, a front-wheel steering angle tracking method was designed, and the trajectory tracking was realized by the torque control of steering motor. At the same time, a vehicle yaw stability controller was designed to ensure the vehicle yaw stability by controlling the yaw rate tracking error. Finally, a CarSim-Simulink co-simulation model was established and used for simulation test. The results show that, the unknown input observer has a better effect on front-wheel steering angle estimation, which provides a reliable information source for vehicle coordinated control. And the coordinated control strategy can ensure the vehicle yaw stability and complete the vehicle trajectory tracking at the same time.

Hybrid Encryption Method for Secure Storage of Medical Data

KANG Haiyan, DENG Jie

2021, 41(10): 1058-1068. doi:10.15918/j.tbit1001-0645.2020.198

Abstract(564) PDF(331)

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In real life, the patient's EMR(electronic medical record) is usually managed by the hospital, and the EMR data are also stored by the EMR management system. This kind of centralized storage method will make the patient's privacy information exist the risk of leakage when sharing information across hospitals. Starting with the key technology of information security-digital encryption technology, the classical symmetric encryption algorithm (data encryption standard, DES) and asymmetric encryption algorithm (Rivest-Shamir-Adleman,RSA) were analyzed, and a hybrid encryption scheme was proposed for medical data security storage, improving the security limitations in data encryption and proposes. Firstly, an improved algorithm IBDES was proposed to enhance the security strength by double encryption. Secondly, an improved algorithm EPNRSA was proposed to reduce the time complexity of RSA encryption and ensure the security quality of encryption. Thirdly, a hybrid encryption scheme based on IBDES and EPNRSA was formed. Finally, theoretical analysis and simulation experiments were carried out.The results show that the scheme can provide a better encryption and decryption effect, fast execution speed and high security, being an ideal method for medical data security storage.

Fault Diagnosis Method for Aviation Transformer Rectifier Unit Based on SDAE-PSOSVM

SHI Xudong, XU Haiyi, WU Donghua, YANG Zhangang, LI Yunfu

2021, 41(10): 1069-1076,1083. doi:10.15918/j.tbit1001-0645.2020.176

Abstract(545) PDF(286)

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Due to the high similarity of the fault characteristics of aviation transformer rectifier diodes in different fault modes, it is difficult to distinguish the fault characteristics. To solve the problem, a fault diagnosis method was proposed based on stacked denoising auto encoder (SDAE) combined with particle swarm optimization support vector machine (PSOSVM). Firstly, a simulation model of aviation transformer rectifier was built to get the fault data from simulation of different fault modes. Then the SDAE method was used to extract the fault features from high-dimensional fault signals and establish fault feature sets. Finally, PSOSVM method was used to diagnose fault and to compare the effectiveness with common fault diagnosis methods. The fault diagnosis results show that the accuracy of the SDAE-PSOSVM method can reach up to 96% and functionally extract the features of high-dimensional fault data signals to improve the discrimination between different fault modes.

Infrared and Visible Image Fusion Based on Residual Dense Block and Auto-Encoder Network

WANG Jianzhong, XU Haonan, WANG Hongfeng, YU Zibo

2021, 41(10): 1077-1083. doi:10.15918/j.tbit1001-0645.2021.131

Abstract(607) PDF(388)

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Infrared and visible image fusion is an effective means to obtain high-quality target images in complex environments. It has broad application prospects in the fields of target detection and tracking, image enhancement, remote sensing, and medical treatment. In order to solve the problems of the current deep learning-based infrared and visible image fusion methods that the network cannot fully extract featuresd, cannot fully utilize the feature information, and the clarity of fusion image is low, this paper proposes an end-to-end image fusion network based on residual dense block and auto-encoder, which uses an encoder network based on residual dense block to decompose the image into a background feature map and a detailed feature map, after that the two feature maps will be fused, and then reconstructed by the decoder to restore the final fusion image. The test results show that the method in this paper can obtain a fused image with high definition, prominent target and obvious outline, compared with the current representative fusion methods, the six fusion quality evaluation indicators of SF, AG, CC, SCD, Qabf, and SSIM have been improved in different degrees, especially has a huge advantage in the clarity of the fusion image. And for complex environmental images such as blur, occlusion, backlighting, and smoke, there is a good fusion effect.

Research on In-Band Continuous Wave Electromagnetic Interference Effect of Unmanned Aerial Vehicle Data Link

XU Tong, CHEN Yazhou, WANG Yuming, ZHAO Min

2021, 41(10): 1084-1094. doi:10.15918/j.tbit1001-0645.2021.031

Abstract(659) PDF(309)

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Data-link is an important sub-system of unmanned aerial vehicle (UAV) and a key link to ensure the UAV air-ground communication. However, it is easy to be affected by external electromagnetic interference, leading to communication interruption and even hardware damage. Based on the front-end coupling electromagnetic sensitivity of a certain UAV data link, an equivalent injection test was carried out. The effect law of single frequency and dual frequency electromagnetic interference on data link were studied, and the loss-of-lock threshold of the sensitive frequency points of the data link and the changing trend of the bit error rate and the signal noise ratio were obtained. The results show that:due to the high-power interference signal passing through the automatic gain control (AGC) circuit, the output power of the intermediate frequency (IF) useful signal is reduced in the radio frequency (RF) front end, resulting in a reduction of signal noise ratio (SNR) and an increase in the bit error rate (BER) in data terminal. When the dual-frequency interference is both in-band, the compression effect on the gain of useful signal at the front end is stronger than that of the single-frequency interference. Therefore, when the data-link is out of lock, the threshold of any one of the dual-frequency interference is lower than that of the single-frequency interference, which indicates that a multi-source nonlinear enhancement effect exists in the in-band jamming.

Modeling and Evaluating Method of Second-Order Intermodulation LF Blocking Effect for Spectrum-Dependent Equipment

WEI Guanghui, ZHENG Jianyong, ZHAO Hongze, LI Mei, DU Xue

2021, 41(10): 1095-1102. doi:10.15918/j.tbit1001-0645.2020.224

Abstract(522) PDF(267)

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To test and evaluate the adaptability of the spectrum-dependent equipment to complex electromagnetic environment, introducing a LF blocking interference factor and the relative value of LF interference level, a second-order intermodulation LF blocking effect model was established to investigate the mechanism of second-order intermodulation LF blocking effect. Combining theoretical derivation and experimental measurement, a method was provided to determine the model parameter, the modeling and evaluating processes were established for the second-order intermodulation LF blocking effect. Finally, taking a satellite navigation receiver as the test equipment, an experimental verification was carried out. The results show that, using the second-order intermodulation LF blocking effect model parameters of the equipment under test at a specific working frequency, according to the tested data of the critical interference field strength of the single frequency electromagnetic radiation blocking and the distribution parameters of environmental electromagnetic field spectrum, the second-order intermodulation LF blocking effect of the spectrum-dependent equipment can be objectively evaluated, error is within 2 dB.

Study on High Frequency Characterizations of Coaxially Shielded TSV with Mixed Dielectric Layer

DING Yingtao, WANG Yiding, XIAO Lei, WANG Qining, CHEN Zhiwei

2021, 41(10): 1103-1108. doi:10.15918/j.tbit1001-0645.2018.279

Abstract(556) PDF(289)

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To improve high-frequency characteristics of Through Silicon Via (TSV) interposer in T/R modules, a coaxially shielded TSV with mixed dielectric layer was proposed in this paper, involving novel structure and simple fabrication process. The parameters such as the number of ground TSV, the diameter of TSV, and the thickness of the mixed dielectric layer were simulated and optimized. Compared with traditional coaxial TSV, the coaxially shielded TSV with mixed dielectric layer shows excellent RF transmission performance including return loss, insertion loss and crosstalk in 1~45 GHz frequency range.

Thermal-Mechanical Reliability Characterization of Low-Resistivity Silicon-TSVs (LRS-TSV) and Copper-Filled TSVs

DENG Xiaoying, YU Siqi, WANG Shiwei, XIE Yi

2021, 41(10): 1109-1113. doi:10.15918/j.tbit1001-0645.2017.148

Abstract(562) PDF(284)

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The thermal mechanical reliability of low resistivity silicon through silicon via (LRS-TSV) and copper-filled TSV was analyzed and compared based on finite element method (FEM). The results show that, the protrusion area of LRS-TSV emerges mainly upon polymer insulation and the aluminum layer above the silicon pillar, the height is 82 nm and 76 nm respectively. The protrusion area of copper-filled TSV emerges mainly upon the copper layer above the copper pillar, the maximum value is 150 nm. The largest stress of the LRS-TSV emerges on both sides of the polymer insulation layer, the maximum value can reach up to 1 005 MPa. And the largest stress of Copper-filled TSV emerges on the outside of the central copper pillar, the maximum value is 1 227 MPa. In addition, the largest interfacial stress of the two types of TSV structure all appears at both ends near the TSV. The stress of the LRS-TSV can not exceed 400 MPa, while the stress of copper-filled TSV can exceed 800 MPa. Based on the above results, it is concluded that the LRS-TSV possesses higher thermal mechanical reliability than the copper-filled TSV.

Preparation of Porous Aromatic Polyamide Membranes and Their Dielectric Properties

ZHU Huanhuan, NIU Mingkang, HUANG Guiming, WANG Qun, LIANG Zhiquan, JIAO Qingze, FENG Caihong, ZHAO Yun, LÜ Yuzhen

2021, 41(10): 1114-1119. doi:10.15918/j.tbit1001-0645.2020.179

Abstract(522) PDF(336)

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Poly m-phenylene isophth alamide(PMIA) was synthesized using m-phenylenediamine and isophthaloyl chloride as monomers, 2-methylpyridine as acid binding agent by the low-temperature solution polymerization in N, N-dimethylacetamide (DMAc). Porous PMIA membranes with different pore structures were then prepared by non-solvent induced phase separation, and ethanol was used as non-solvent coagulation bath. The structures of PMIA were characterized by Fourier transform infrared and¹H-nuclear magnetic resonance. The influence of polymer concentration on the pore structure and dielectric constant of the porous PMIA membrane was studied. Results show that when the concentration of PMIA is 21%, 17% and 15%, porous membranes with regular pore morphologies can all be obtained. Their dielectric constants are 2.31,2.07 and 1.89 respectively at 1 MHz, decreased by 63%, 67% and 70% than 6.22 of PMIA standard membrane.

Modification of HZSM-5 Zeolites and Their Catalytic Performances for Cracking Waste Tires to Produce Light Olefins

ZHAO Yun, QIN Shikai, FU Ruru, SHI Quan, FENG Caihong, JIAO Qingze, LI Hansheng, SHI Daxin

2021, 41(10): 1120-1127. doi:10.15918/j.tbit1001-0645.2020.146

Abstract(754) PDF(304)

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Commercial HZSM-5 molecular sieves with SiO₂/Al₂O₃ratio of 200 were modified using different concentrations of sodium hydroxide solution.Their crystal structures, pore structures, morphologies and acidity were characterized by XRD, SEM, NH₃-TPD and N₂adsorption and desorption measurements.The catalytic performances of the modified HZSM-5 molecular sieves for the catalytic cracking of waste tires were investigated. The results show that pore structure and acidity of modified HZSM-5 can be adjusted by changing the concentration of sodium hydroxide solution. With the increase of the concentration of sodium hydroxide solution, the average pore size of HZSM-5 increases gradually, while the mesoporous volume and the amount of acid increases at first and then decreases.The HZSM-5 zeolite modified with 0.4 mol/L of sodium hydroxide solution shows the most mesoporous pore volume and acid content. When it was used to catalyze the cracking of waste tires, the selectivity of light olefins is high up to 32.39%, being much higher than that of commercial HZSM-5 zeolites.

Screening of Neurochemical Biomarkers for Rats with Nerve Injury Induced by Whole-Brain Irradiation

MENG Xianshuang, BAI Hua, MA Qiang, ZHANG Peng, MA Hong, DENG Yulin

2021, 41(10): 1128-1136. doi:10.15918/j.tbit1001-0645.2021.074

Abstract(547) PDF(276)

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Screening of neurochemical biomarkers was performed in peripheral blood serum from rats with nerve injury induced by whole-brain irradiation(WBI).Serum of rats treated with different doses of WBI(0,10,and 30 Gy) and fractional cumulative radiation(10 Gy×3) were determined for the concentration of 42 neurochemicals using the previously established chemical derivatization and ultra-high performance liquid chromatography-tandem mass spectrometry method followed by statistical analysis based on targeted metabolomics. Univariate statistical analysis indicated that the concentrations of norepinephrine, acetylcholine, γ-aminobutyric acid, tyramine, glutamic acid, tyrosine, tryptophan, melatonin, α-alanine, and glycine were significantly (p<0.05) lower than the control group (0 Gy), while the concentrations of acetylcholine and melatonin changed in the opposite trend (p<0.05); Meanwhile the variation degree of neurochemicals in the 10 Gy×3 group was found lower than that in the 30 Gy group, indicating that the disturbance degree of neurochemicals caused by cumulative irradiation was lower than that caused by single irradiation of the same dose. Combining with the variable importance in the projection(VIP) in the multivariate statistical OPLS-DA model, the proposed method has selected acetylcholine,glutamate,tyramine,and melatonin as the potential biomarkers for the nerve injury induced by WBI.

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