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Error Analysis of MSAV Scheme for Two Phase Magnetohydrodynamic Diffuse Interface Model
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作者 HU Kun WANG Danxia +1 位作者 ZHANG Jianwen JIA Hongen 《应用数学》 北大核心 2025年第2期348-371,共24页
In this paper,we develop a multi-scalar auxiliary variables(MSAV)scheme for the Cahn-Hilliard Magnetohydrodynamics system by introducing two scalar auxiliary variables(SAV).This scheme is linear,fully decoupled and un... In this paper,we develop a multi-scalar auxiliary variables(MSAV)scheme for the Cahn-Hilliard Magnetohydrodynamics system by introducing two scalar auxiliary variables(SAV).This scheme is linear,fully decoupled and unconditionally stable in energy.Subsequently,we provide a detailed implementation procedure for full decoupling.Thus,at each time step,only a series of linear differential equations with constant coefficients need to be solved.To validate the effectiveness of our approach,we conduct an error analysis for this first-order scheme.Finally,some numerical experiments are provided to verify the energy dissipation of the system and the convergence of the proposed approach. 展开更多
关键词 Cahn-Hilliard Magnetohydrodynamics system Fully decoupled Stability in energy error analysis
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Vibration-induced bias error reduction using loop gain compensation for high-precision fiber optic gyroscopes
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作者 CHEN Heyu QIN Xuexin +2 位作者 XIE Huan KONG Linghai ZHENG Yue 《Journal of Systems Engineering and Electronics》 2025年第1期224-232,共9页
Vibration-induced bias deviation,which is generated by intensity fluctuations and additional phase differences,is one of the vital errors for fiber optic gyroscopes(FOGs)operating in vibration environment and has seve... Vibration-induced bias deviation,which is generated by intensity fluctuations and additional phase differences,is one of the vital errors for fiber optic gyroscopes(FOGs)operating in vibration environment and has severely restricted the applications of high-precision FOGs.The conventional methods for suppressing vibration-induced errors mostly concentrate on reinforcing the mechanical structure and optical path as well as the compensation under some specific operation parameters,which have very limited effects for high-precision FOGs maintaining performances under vibration.In this work,a technique of suppressing the vibration-induced bias deviation through removing the part related to the varying gain from the rotation-rate output is put forward.Particularly,the loop gain is extracted out by adding a gain-monitoring wave.By demodulating the loop gain and the rotation rate simultaneously under distinct frequencies and investigating their quantitative relationship,the vibrationinduced bias error is compensated without limiting the operating parameters or environments,like the applied modulation depth.The experimental results show that the proposed method has achieved the reduction of bias error from about 0.149°/h to0.014°/h during the random vibration with frequencies from20 Hz to 2000 Hz.This technique provides a feasible route for enhancing the performances of high-precision FOGs heading towards high environmental adaptability. 展开更多
关键词 vibration-induced error fiber optic gyroscope(FOG) loop gain
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Optimization of mesh characteristics of gear pair considering influence of assembly errors
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作者 ZHAO Xiao-jian MA Hui +5 位作者 MA Ze-yu LIU Jia-qi CAO Peng WU Yu-ping DING Xiang-fu ZHAO Tian-yu 《Journal of Central South University》 2025年第4期1400-1430,共31页
Gear assembly errors can lead to the increase of vibration and noise of the system,which affect the stability of system.The influence can be compensated by tooth modification.Firstly,an improved three-dimensional load... Gear assembly errors can lead to the increase of vibration and noise of the system,which affect the stability of system.The influence can be compensated by tooth modification.Firstly,an improved three-dimensional loaded tooth contact analysis(3D-LTCA)method which can consider tooth modification and coupling assembly errors is proposed,and mesh stiffness calculated by proposed method is verified by MASTA software.Secondly,based on neural network,the surrogate model(SM)that maps the relationship between modification parameters and mesh mechanical parameters is established,and its accuracy is verified.Finally,SM is introduced to establish an optimization model with the target of minimizing mesh stiffness variations and obtaining more even load distribution on mesh surface.The results show that even considering training time,the efficiency of gear pair optimization by surrogate model is still much higher than that by LTCA method.After optimization,the mesh stiffness fluctuation of gear pair with coupling assembly error is reduced by 34.10%,and difference in average contact stresses between left and right regions of the mesh surface is reduced by 62.84%. 展开更多
关键词 helical gear mesh characteristics gear tooth modification assembly errors neural network multi-objective optimization
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Temperature error compensation method for fiber optic gyroscope based on a composite model of k-means,support vector regression and particle swarm optimization
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作者 CAO Yin LI Lijing LIANG Sheng 《Journal of Systems Engineering and Electronics》 2025年第2期510-522,共13页
As the core component of inertial navigation systems, fiber optic gyroscope (FOG), with technical advantages such as low power consumption, long lifespan, fast startup speed, and flexible structural design, are widely... As the core component of inertial navigation systems, fiber optic gyroscope (FOG), with technical advantages such as low power consumption, long lifespan, fast startup speed, and flexible structural design, are widely used in aerospace, unmanned driving, and other fields. However, due to the temper-ature sensitivity of optical devices, the influence of environmen-tal temperature causes errors in FOG, thereby greatly limiting their output accuracy. This work researches on machine-learn-ing based temperature error compensation techniques for FOG. Specifically, it focuses on compensating for the bias errors gen-erated in the fiber ring due to the Shupe effect. This work pro-poses a composite model based on k-means clustering, sup-port vector regression, and particle swarm optimization algo-rithms. And it significantly reduced redundancy within the sam-ples by adopting the interval sequence sample. Moreover, met-rics such as root mean square error (RMSE), mean absolute error (MAE), bias stability, and Allan variance, are selected to evaluate the model’s performance and compensation effective-ness. This work effectively enhances the consistency between data and models across different temperature ranges and tem-perature gradients, improving the bias stability of the FOG from 0.022 °/h to 0.006 °/h. Compared to the existing methods utiliz-ing a single machine learning model, the proposed method increases the bias stability of the compensated FOG from 57.11% to 71.98%, and enhances the suppression of rate ramp noise coefficient from 2.29% to 14.83%. This work improves the accuracy of FOG after compensation, providing theoretical guid-ance and technical references for sensors error compensation work in other fields. 展开更多
关键词 fiber optic gyroscope(FOG) temperature error com-pensation composite model machine learning CLUSTERING regression.
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Deep unfolded amplitude-phase error self-calibration network for DOA estimation
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作者 ZHU Hangui CHEN Xixi +1 位作者 MA Teng WANG Yongliang 《Journal of Systems Engineering and Electronics》 2025年第2期353-361,共9页
To tackle the challenges of intractable parameter tun-ing,significant computational expenditure and imprecise model-driven sparse-based direction of arrival(DOA)estimation with array error(AE),this paper proposes a de... To tackle the challenges of intractable parameter tun-ing,significant computational expenditure and imprecise model-driven sparse-based direction of arrival(DOA)estimation with array error(AE),this paper proposes a deep unfolded amplitude-phase error self-calibration network.Firstly,a sparse-based DOA model with an array convex error restriction is established,which gets resolved via an alternating iterative minimization(AIM)algo-rithm.The algorithm is then unrolled to a deep network known as AE-AIM Network(AE-AIM-Net),where all parameters are opti-mized through multi-task learning using the constructed com-plete dataset.The results of the simulation and theoretical analy-sis suggest that the proposed unfolded network achieves lower computational costs compared to typical sparse recovery meth-ods.Furthermore,it maintains excellent estimation performance even in the presence of array magnitude-phase errors. 展开更多
关键词 direction of arrival(DOA) sparse recovery alternat-ing iterative minimization(AIM) deep unfolding amplitude-phase error.
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Approach to dynamic error suppression in ground vehicle gravimetry based on external velocity compensation
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作者 LI Xinyu ZHOU Zhaofa +2 位作者 ZHANG Zhili CHANG Zhenjun HAO Shiwen 《Journal of Systems Engineering and Electronics》 2025年第2期580-596,共17页
The process of ground vehicle dynamic gravimetry is inevitably affected by the carrier’s maneuvering acceleration,which makes the result contain a large amount of dynamic error.In this paper,we propose a dynamic erro... The process of ground vehicle dynamic gravimetry is inevitably affected by the carrier’s maneuvering acceleration,which makes the result contain a large amount of dynamic error.In this paper,we propose a dynamic error suppression method of gravimetry based on the high-precision acquisition of external velocity for compensating the horizontal error of the inertial plat-form.On the basis of platform gravity measurement,firstly,the dynamic performance of the system is enhanced by optimizing the horizontal damping network of the inertial platform and selecting its parameter.Secondly,an improved federal Kalman filtering algorithm and a fault diagnosis method are designed using strapdown inertial navigation system(SINS),odometer(OD),and laser Doppler velocimeter(LDV).Simulation validates that these methods can improve the accuracy and robustness of the external velocity acquisition.Three survey lines are selected in Tianjin,China,for the gravimetry experiments with different maneuvering levels,and the results demonstrate that after dynamic error suppression,the internal coincidence accuracies of smooth and uniform operation,obvious acceleration and deceleration operation,and high-dynamic operation are improved by 70.2%,73.6%,and 77.9%to reach 0.81 mGal,1.30 mGal,and 1.94 mGal,respectively,and the external coinci-dence accuracies during smooth and uniform operation are improved by 48.6%up to 1.66 mGal.It is shown that the pro-posed method can effectively suppress the dynamic error,and that the accuracy improvement increases with carrier maneuver-ability.However,the amount of residual error that can not be entirely eliminated increases as well,so the ground vehicle dynamic gravimetry should be maintained in the carrier for smooth and uniform operation. 展开更多
关键词 ground vehicle gravimetry dynamic error suppres-sion external velocity compensation federal Kalman filter fault diagnosis and isolation
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Phase error analysis and optimization for chirp transform spectrometer
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作者 RU Penglei LIU Mengwei +1 位作者 HU Baifan WANG Wen 《Journal of Systems Engineering and Electronics》 2025年第3期597-608,共12页
In the field of deep space exploration,the rapid development of terahertz spectrometer has put forward higher requirements to the back-end chirp transform spectrometer(CTS)system.In order to simultaneously meet the me... In the field of deep space exploration,the rapid development of terahertz spectrometer has put forward higher requirements to the back-end chirp transform spectrometer(CTS)system.In order to simultaneously meet the measurement requirements of wide bandwidth and high accuracy spectral lines,we built a CTS system with an analysis bandwidth of 1 GHz and a frequency resolution of 100 kHz around the surface acoustic wave(SAW)chirp filter with a bandwidth of 1 GHz.In this paper,the relationship between the CTS nonlinear phase error shift model and the basic measurement parameters is studied,and the effect of CTS phase mismatch on the pulse compression waveform is analyzed by simulation.And the expander error optimization method is proposed for the problem that the large nonlinear error of the expander leads to the unbalanced response of the CTS system and the serious distortion of the compressed pulse waveform under large bandwidth.It is verified through simulation and experiment that the method is effective for reducing the root mean square error(RMSE)of the phase of the expander from 18.75°to 6.65°,reducing the in-band standard deviation of the CTS frequency resolution index from 8.43 kHz to 4.72 kHz,solving the problem of serious distortion of the compressed pulse waveform,and improving the uneven CTS response under large bandwidth. 展开更多
关键词 chirp transform spectrometer(CTS) microwave heterodyne spectroscopy phase error compensation surface acoustic wave(SAW) wide bandwidth
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Optimization of processing parameters for microwave drying of selenium-rich slag using incremental improved back-propagation neural network and response surface methodology 被引量:4
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作者 李英伟 彭金辉 +2 位作者 梁贵安 李玮 张世敏 《Journal of Central South University》 SCIE EI CAS 2011年第5期1441-1447,共7页
In the non-linear microwave drying process, the incremental improved back-propagation (BP) neural network and response surface methodology (RSM) were used to build a predictive model of the combined effects of ind... In the non-linear microwave drying process, the incremental improved back-propagation (BP) neural network and response surface methodology (RSM) were used to build a predictive model of the combined effects of independent variables (the microwave power, the acting time and the rotational frequency) for microwave drying of selenium-rich slag. The optimum operating conditions obtained from the quadratic form of the RSM are: the microwave power of 14.97 kW, the acting time of 89.58 min, the rotational frequency of 10.94 Hz, and the temperature of 136.407 ℃. The relative dehydration rate of 97.1895% is obtained. Under the optimum operating conditions, the incremental improved BP neural network prediction model can predict the drying process results and different effects on the results of the independent variables. The verification experiments demonstrate the prediction accuracy of the network, and the mean squared error is 0.16. The optimized results indicate that RSM can optimize the experimental conditions within much more broad range by considering the combination of factors and the neural network model can predict the results effectively and provide the theoretical guidance for the follow-up production process. 展开更多
关键词 microwave drying response surface methodology optimization incremental improved back-propagation neural network PREDICTION
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Efficient unequal error protection for online fountain codes 被引量:1
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作者 SHI Pengcheng WANG Zhenyong +1 位作者 LI Dezhi LYU Haibo 《Journal of Systems Engineering and Electronics》 SCIE CSCD 2024年第2期286-293,共8页
In this paper,an efficient unequal error protection(UEP)scheme for online fountain codes is proposed.In the buildup phase,the traversing-selection strategy is proposed to select the most important symbols(MIS).Then,in... In this paper,an efficient unequal error protection(UEP)scheme for online fountain codes is proposed.In the buildup phase,the traversing-selection strategy is proposed to select the most important symbols(MIS).Then,in the completion phase,the weighted-selection strategy is applied to provide low overhead.The performance of the proposed scheme is analyzed and compared with the existing UEP online fountain scheme.Simulation results show that in terms of MIS and the least important symbols(LIS),when the bit error ratio is 10-4,the proposed scheme can achieve 85%and 31.58%overhead reduction,respectively. 展开更多
关键词 online fountain code random graph unequal error protection(UEP) rateless code
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System error iterative identification for underwater positioning based on spectral clustering
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作者 LU Yu WANG Jiongqi +3 位作者 HE Zhangming ZHOU Haiyin XING Yao ZHOU Xuanying 《Journal of Systems Engineering and Electronics》 SCIE CSCD 2024年第4期1028-1041,共14页
The observation error model of the underwater acous-tic positioning system is an important factor to influence the positioning accuracy of the underwater target.For the position inconsistency error caused by consideri... The observation error model of the underwater acous-tic positioning system is an important factor to influence the positioning accuracy of the underwater target.For the position inconsistency error caused by considering the underwater tar-get as a mass point,as well as the observation system error,the traditional error model best estimation trajectory(EMBET)with little observed data and too many parameters can lead to the ill-condition of the parameter model.In this paper,a multi-station fusion system error model based on the optimal polynomial con-straint is constructed,and the corresponding observation sys-tem error identification based on improved spectral clustering is designed.Firstly,the reduced parameter unified modeling for the underwater target position parameters and the system error is achieved through the polynomial optimization.Then a multi-sta-tion non-oriented graph network is established,which can address the problem of the inaccurate identification for the sys-tem errors.Moreover,the similarity matrix of the spectral cluster-ing is improved,and the iterative identification for the system errors based on the improved spectral clustering is proposed.Finally,the comprehensive measured data of long baseline lake test and sea test show that the proposed method can accu-rately identify the system errors,and moreover can improve the positioning accuracy for the underwater target positioning. 展开更多
关键词 acoustic positioning reduced parameter system error identification improved spectral clustering accuracy analy-sis
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Research on fixed-time time-varying formation of heterogeneous multi-agent systems based on tracking error observer under DoS attacks
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作者 Jiqing Luo Husheng Fang +2 位作者 Yue Zhong Jing Zhang Shengli Song 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2024年第12期211-225,共15页
In this paper,the fixed-time time-varying formation of heterogeneous multi-agent systems(MASs) based on tracking error observer under denial-of-service(DoS) attacks is investigated.Firstly,the dynamic pinning strategy... In this paper,the fixed-time time-varying formation of heterogeneous multi-agent systems(MASs) based on tracking error observer under denial-of-service(DoS) attacks is investigated.Firstly,the dynamic pinning strategy is used to reconstruct the communication channel for the system that suffers from DoS attacks to prevent the discontinuous transmission information of the communication network from affecting MASs formation.Then,considering that the leader state is not available to each follower under DoS attacks,a fixed-time distributed observer without velocity information is constructed to estimate the tracking error between followers and the leader.Finally,adaptive radial basis function neural network(RBFNN) is used to approximate the unknown ensemble disturbances in the system,and the fixed-time time-varying formation scheme is designed with the constructed observer.The effectiveness of the proposed control algorithm is demonstrated by the numerical simulation. 展开更多
关键词 Denial-of-service attacks Dynamic pinning Fixed-time tracking error observer Adaptive RBFNN Fixed-time time-varying formation
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Missile guidance law design based on free-time convergent error dynamics
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作者 LIU Yuanhe XIE Nianhao +1 位作者 LI Kebo LIANG Yan’gang 《Journal of Systems Engineering and Electronics》 SCIE CSCD 2024年第5期1315-1325,共11页
To solve the finite-time error-tracking problem in mis-sile guidance,this paper presents a unified design approach through error dynamics and free-time convergence theory.The proposed approach is initiated by establis... To solve the finite-time error-tracking problem in mis-sile guidance,this paper presents a unified design approach through error dynamics and free-time convergence theory.The proposed approach is initiated by establishing a desired model for free-time convergent error dynamics,characterized by its independence from initial conditions and guidance parameters,and adjustable convergence time.This foundation facilitates the derivation of specific guidance laws that integrate constraints such as leading angle,impact angle,and impact time.The theoretical framework of this study elucidates the nuances and synergies between the proposed guidance laws and existing methodologies.Empirical evaluations through simulation comparisons underscore the enhanced accuracy and adaptability of the proposed laws. 展开更多
关键词 guidance design free-time convergence error dynamics approach impact angle constraint impact time constraint
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重型高精度惯性摩擦焊机移动夹具定位误差分析 被引量:1
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作者 孙宝玉 李焕震 +2 位作者 张刚 余卓成 关英俊 《中国机械工程》 北大核心 2025年第2期238-244,254,共8页
针对航空发动机典型零件的高精度焊接质量需求,设计了一种新型重型高精度惯性摩擦焊机移动夹具的夹紧机构,对移动夹具进行定位误差分析。建立一种移动夹具定位元件公差与焊件位姿误差映射关系的理论模型,在忽略其他影响因素(如机床误差... 针对航空发动机典型零件的高精度焊接质量需求,设计了一种新型重型高精度惯性摩擦焊机移动夹具的夹紧机构,对移动夹具进行定位误差分析。建立一种移动夹具定位元件公差与焊件位姿误差映射关系的理论模型,在忽略其他影响因素(如机床误差、焊件的定位基准面误差、夹紧力和热变形引起的误差等)对焊件焊接精度影响的情况下,利用该误差理论模型,根据某型转子要求的焊接精度,通过误差理论模型计算得到移动夹具夹紧机构定位元件的尺寸公差范围,再根据该尺寸公差范围设计移动夹具夹紧机构并夹装焊件,从而完成焊接试验。试验结果显示,同轴度误差、平行度误差和轴向缩短量误差三项误差中的最大误差分别为∅0.04 mm、0.02 mm和0.12 mm,各项误差检测结果均达到所要求的焊接精度(同轴度误差:∅0.06 mm;平行度误差:0.04/300 mm;轴向缩短量误差:±0.2 mm),证明计算得到的各定位元件的公差范围合理,所建立的误差理论模型对重型惯性摩擦焊机设计中移动夹具定位元件的公差分配具有重要的理论指导意义。 展开更多
关键词 移动夹具 定位误差 误差映射 焊接精度 公差
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数控机床移动工作台定位精度预测的建模、仿真及实验 被引量:1
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作者 杨洪涛 秦鹏飞 +3 位作者 李莉 刘柄瑶 金磊 姜西祥 《机电工程》 北大核心 2025年第2期351-361,共11页
随着使用时间的延长,数控机床移动工作台会出现部件磨损、失效等现象,进而导致工作台定位精度降低。为了精确预测移动工作台的精度损失,以数控机床移动工作台为研究对象,在考虑载荷、运动速度、温度和运行时间等影响因素的基础上,建立... 随着使用时间的延长,数控机床移动工作台会出现部件磨损、失效等现象,进而导致工作台定位精度降低。为了精确预测移动工作台的精度损失,以数控机床移动工作台为研究对象,在考虑载荷、运动速度、温度和运行时间等影响因素的基础上,建立了工作台的定位误差预测模型,对工作台定位误差随时间的变化情况,进行了理论计算、仿真分析及实验验证。首先,在分析滚动直线导轨副的摩擦磨损机理和负载作用下产生的表面接触变形的基础上,建立了导轨副表面滚珠与滚道在接触载荷作用下的磨损模型,以及滚珠丝杆在电机扭矩、轴向力和温度作用下产生的扭转变形、螺距变化及热膨胀误差模型,还建立了工作台随使用时间变化的定位误差预测模型(因导轨副磨损与滚珠丝杆变形均会使工作台产生定位误差,两部分误差之和为定位精度损失预测模型);然后,开展了不同负载、运动速度、温度等因素影响下的理论计算与仿真分析;最后,在一组特定负载、速度、温度的条件下,进行了定位误差的测量实验,验证了上述预测模型的准确性。研究结果表明:在不同的因素影响作用下,仿真结果、实验结果与理论结果相比,其总体的变化趋势趋于一致,且经拟合对比分析,定位误差的仿真、实验与理论之间的最大相对误差为15.9%。该误差预测模型能够有效预测工作台的定位误差,为数控机床加工精度的预测奠定了基础。 展开更多
关键词 移动工作台运行时间 定位精度损失 定位误差模型 导轨副磨损模型 滚珠丝杆变形 热膨胀误差
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面齿轮蜗杆砂轮磨削安装误差分析及补偿
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作者 李国龙 蒲峙杉 +3 位作者 何坤 王梓宇 宁行 张薇 《计算机集成制造系统》 北大核心 2025年第2期452-463,共12页
为了提高面齿轮的磨削加工精度,提出一种齿面误差补偿方法。基于普通蜗杆砂轮磨齿机的机械结构,分析其磨削原理,规划砂轮磨削运动轨迹,并分别建立含刀具同轴度误差和工件平面度误差的面齿轮齿面模型,分析各自对齿面误差的影响规律;提出... 为了提高面齿轮的磨削加工精度,提出一种齿面误差补偿方法。基于普通蜗杆砂轮磨齿机的机械结构,分析其磨削原理,规划砂轮磨削运动轨迹,并分别建立含刀具同轴度误差和工件平面度误差的面齿轮齿面模型,分析各自对齿面误差的影响规律;提出一种基于自适应完备集合经验模态分解的随机误差分离方法,消除齿面测量结果中的随机误差;研究齿面误差分布情况,分析可能造成误差的原因,并依据齿面误差影响规律对机床参数进行修正,以实现误差补偿。最后完成磨齿和测量,结果表明齿面最大法向误差减小79.8%,最大齿形和齿向误差分别减小67.6%和72.4%,齿面精度提高显著。 展开更多
关键词 面齿轮 蜗杆砂轮磨削 误差分析 误差分离 误差补偿
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高精度椭圆阵列电流传感器误差优化算法研究 被引量:1
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作者 沈悦 陆佳嘉 +2 位作者 唐玥 权硕 褚子扬 《传感器与微系统》 北大核心 2025年第2期39-43,共5页
为了减小由于矩形导体偏心和倾斜导致的传感器测量误差,实现电流高精度测量,提出一种基于灰狼优化(GWO)算法优化反向传播(BP)神经网络的椭圆阵列霍尔电流传感器误差优化方案。首先,基于三维磁场模型确定导体偏心参数和倾斜参数,并进行... 为了减小由于矩形导体偏心和倾斜导致的传感器测量误差,实现电流高精度测量,提出一种基于灰狼优化(GWO)算法优化反向传播(BP)神经网络的椭圆阵列霍尔电流传感器误差优化方案。首先,基于三维磁场模型确定导体偏心参数和倾斜参数,并进行电流反演,得出电流积分模型;然后,使用BP神经网络估计导体参数,并引入GWO算法优化BP神经网络的初始权值和阈值,构建导体状态参数估计模型,实现偏心与倾斜误差优化;最后,搭建实验平台,对本文提出的误差优化方案进行验证。实验结果表明:本文提出误差优化方案能够精确估计导体状态参数,进而有效减小偏心误差和倾斜误差,导体X向偏心产生的电流误差减小65.07%,Y向偏心产生的电流误差减小45.74%,偏离Z轴产生的倾斜电流误差减小76.15%。 展开更多
关键词 椭圆阵列传感器 矩形导体 偏心误差 倾斜误差 灰狼优化算法 反向传播神经网络
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一种评价磁流变抛光工艺误差抑制能力的方法
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作者 高博 范斌 +2 位作者 王佳 吴湘 辛强 《激光技术》 北大核心 2025年第1期135-143,共9页
为了分析磁流变加工过程中去除函数对加工精度的影响以及去除函数的抗中频误差性能,采用平滑谱方法对加工中误差抑制能力进行了评估。通过非球面光学元件对平滑谱方法及传统功率谱方法进行了理论分析、仿真实验及实验验证,采用平滑谱方... 为了分析磁流变加工过程中去除函数对加工精度的影响以及去除函数的抗中频误差性能,采用平滑谱方法对加工中误差抑制能力进行了评估。通过非球面光学元件对平滑谱方法及传统功率谱方法进行了理论分析、仿真实验及实验验证,采用平滑谱方法及传统功率谱方法分析了去除函数对非球面光学元件的面形误差和中频误差的抑制能力。结果表明,平滑谱方法对加工中误差抑制能力即去除函数可修正的面形误差值为0.22 mm-1;平滑谱函数可直观地判断去除函数对面形误差和中频误差的抑制能力,并可明确地定量化判断中频误差的变化规律。此方法为磁流变加工中误差抑制能力的评估问题提供了一种解决方案。 展开更多
关键词 光学制造 误差评价 平滑谱曲线 中频误差
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基于顶点邻域双映射的增材制造几何误差预补偿方法
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作者 杨伟东 蔡子行 +3 位作者 孟德状 马千朝 王媛媛 朱东彬 《天津大学学报(自然科学与工程技术版)》 北大核心 2025年第5期487-495,共9页
在构建三维零件的增材制造过程中,零件的成形几何精度受到多种因素的制约,导致实际成形零件的尺寸和形状与原始设计的边界表示(B-rep)模型存在偏差.在须依赖于模型分层处理的增材制造工艺中,分层误差和制造工艺误差对于零件几何尺寸的... 在构建三维零件的增材制造过程中,零件的成形几何精度受到多种因素的制约,导致实际成形零件的尺寸和形状与原始设计的边界表示(B-rep)模型存在偏差.在须依赖于模型分层处理的增材制造工艺中,分层误差和制造工艺误差对于零件几何尺寸的影响最为显著.为了减少几何误差,通常在预处理阶段对STL模型进行误差预补偿.本文提出了一种基于三角网格顶点邻域双映射的误差补偿方法,通过重建STL模型三角网格顶点的拓扑关系,消除冗余信息并优化顶点邻域的三角面片索引链表,并依据三角面片与顶点的法向量方向映射关系,以及几何误差模型预测值与顶点偏移量的距离映射关系,结合三角面片权重计算顶点的误差补偿量,最终生成经过补偿的STL模型.为验证所提出方法的有效性,本文以砂型黏结剂喷射(BJ)工艺为例,对于所设计的多特征砂型标准件进行几何误差补偿前后的实验对比,结果表明:经过补偿后的标准件,其相对误差降幅均在63.00%以上,打印零件的成形精度得到了大幅提升. 展开更多
关键词 黏结剂喷射工艺 增材制造 几何误差 误差补偿
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土力学溃坝模型的理论与方法评价 被引量:1
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作者 巨江 刘少斌 +1 位作者 张若羽 兰志良 《泥沙研究》 北大核心 2025年第1期1-8,共8页
土力学溃坝模型理论和方法不成熟,包括溃口侵蚀方程漏掉了溃口长度和坝体干容重,溃口纵剖面形状人为假设,溃口横向展宽依赖于侵蚀深度等缺陷,导致计算的溃口流量与流速过程线,溃口下切与库水位降落过程线,溃口展宽过程线均与实测资料偏... 土力学溃坝模型理论和方法不成熟,包括溃口侵蚀方程漏掉了溃口长度和坝体干容重,溃口纵剖面形状人为假设,溃口横向展宽依赖于侵蚀深度等缺陷,导致计算的溃口流量与流速过程线,溃口下切与库水位降落过程线,溃口展宽过程线均与实测资料偏差较大,甚至规律性失真。溃坝扩散模型在经历了溃口纵剖面下切与横断面展宽的中间验证后,又用堰塞湖溃坝和土石坝溃坝实测资料与土力学方法最终对比,更客观地揭示了溃坝机理和规律。反映了坝体几何尺寸、材料特性、溃口水力特性及库容特性对溃口发展的综合影响,在溃坝应急抢险及数字模型平台中具有广泛的应用前景。 展开更多
关键词 堰塞湖 溃坝扩散模型 误差函数 土力学
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LT-1A卫星全极化SAR辐射与极化系统误差稳定性分析:以热带雨林场景为例
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作者 史磊 孙维东 +4 位作者 杨乐 杨杰 赵伶俐 李平湘 刘亚波 《雷达学报(中英文)》 北大核心 2025年第2期405-423,共19页
作为中国新一代天基长波SAR的代表,陆地探测1号01卫星(LT-1A)于2022年1月发射进入太阳同步轨道。LT-1A搭载的长波合成孔径雷达(SAR)工作在L波段,具备单极化、线性双极化、紧缩双极化、全极化等对地观测能力。现有研究主要侧重于LT-1A重... 作为中国新一代天基长波SAR的代表,陆地探测1号01卫星(LT-1A)于2022年1月发射进入太阳同步轨道。LT-1A搭载的长波合成孔径雷达(SAR)工作在L波段,具备单极化、线性双极化、紧缩双极化、全极化等对地观测能力。现有研究主要侧重于LT-1A重轨干涉数据获取能力以及数字高程模型、沉降产品的生产精度评价,对LT-1A的辐射精度、地物极化信息保持能力的研究较为缺乏。该文以热带雨林植被为观测对象,通过不依赖人工定标器的自主定标方法对LT-1A全极化数据辐射误差、极化误差的稳定性进行评价与分析。实验表明:LT-1A传感器的辐射稳定性较好、极化精度优于国际对地观测组织(CEOS)推荐指标。持续对地观测1000 km内归一化雷达截面(NRCS)误差波动小于1 dB(3倍标准差)、5天内重返观测时辐射误差波动小于0.5 dB(3倍标准差);全极化观测模式下系统串扰低于-35 dB甚至达到-40 dB,交叉极化通道不平衡优于0.2 dB与2°,同通道不平衡优于0.5 dB与10°;系统噪声介于-42~-22 dB,平均系统等效热噪声优于-25 dB,热噪声水平随持续对地观测时长的增加有升高。此外,该研究验证了电离层对LT-1A极化数据质量的影响:5°法拉第旋转角造成的图像退化与-20 dB系统串扰带来的影响相当,而3°~20°法拉第旋转角在中、低纬度较为常见,这将带来-21.16~-8.78 dB的极化通道间扰动,即电离层对全极化数据质量的退化相较传感器-40 dB的串扰更为严重。 展开更多
关键词 陆地探测1号卫星 辐射误差 极化误差 热带雨林 合成孔径雷达
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