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Spectrum Characteristics and Transfer Function of the Hydrograph of the Deep Aqueous System 被引量:1
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作者 Chen Baoren, Liu Shuyun, Earth Sciences Dept., Nanjing University, Nanjing, Jiangsu, China Jin Peikang Geological Dept., Tulane University, New Orleans, LA 70118, U.S.A. and Dong Shouyu Hebei Province Seismological Bureau, Shijiazhuang, Hebei, China 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 1993年第4期453-464,共12页
The fluctuation of most of the hydrograph in the deep aqueous system records the fluid pulsation in lithosphere and variation of the earth's crust. Many observations have verified that groundwater is an ideal info... The fluctuation of most of the hydrograph in the deep aqueous system records the fluid pulsation in lithosphere and variation of the earth's crust. Many observations have verified that groundwater is an ideal information carrier of the crust. In this paper, the series of input (precipitation, air pressure, Earth tide etc.) and output (water level, artesian flow) of the deep aqueous system are studied by using the spectrum analysis and system theory. The application concepts of transfer function and the spectral structure of the hydrograph enrich the knowledge of the deep aqueous system. Two typical spectral structures of the hydrograph of the deep aqueous system are obtained by comparing with many water-bearing systems of the Jizhong depression. One is from well Ma-17 and the other is from the well Xinze-5. Finally, the physical models of forming the spectrum of the hydrograph are constructed on the basis of the spectrum research on the deep aqueous system. 展开更多
关键词 deep aqueous system HYDROGRAPH transfer function
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Transfer Function Description of Multirate Sampling Systems
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作者 肖建 唐磊 《Journal of Modern Transportation》 1999年第2期141-147,共7页
Based on the sampler decomposition method and modified Z transform, this paper proposes a pulse transfer function matrix description of the multivariable multirate sampling systems. This multirate sampling system mode... Based on the sampler decomposition method and modified Z transform, this paper proposes a pulse transfer function matrix description of the multivariable multirate sampling systems. This multirate sampling system model has a simple structure, and can be used as a basis for the analysis and synthesis of the multirate sampling systems. 展开更多
关键词 multirate sampling system transfer function computer controlled system
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A method for calculating the transfer function of digital seismograph system
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作者 颜其中 何家斌 高杰 《Acta Seismologica Sinica(English Edition)》 CSCD 2003年第6期693-698,共6页
关键词 digital seismograph system pulse calibration transfer function EMULATION
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Fading Effects on the Performance of OFDM-Based Systems Using Channel Transfer Function
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作者 Chie Dou 《通讯和计算机(中英文版)》 2012年第12期1404-1411,共8页
关键词 OFDM系统 信道增益 性能比较 衰落信道 传递函数 无线局域网 概率分布 信号噪声比
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Transfer Function Model of Multirate Feedback Control Systems
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作者 肖建 唐磊 《Journal of Modern Transportation》 2001年第1期1-7,共7页
Based on the suitably defined multivariable version of Kranc operators and the extended input and output vectors, the multirate sampling plant is transformed to a equivalent time invariant single rate one, then the t... Based on the suitably defined multivariable version of Kranc operators and the extended input and output vectors, the multirate sampling plant is transformed to a equivalent time invariant single rate one, then the transfer function model of the multivariable multirate sampling plant is obtained. By combining this plant model with the time invariant description of the multirate controller in terms of extended vectors, the closed loop transfer function model of the multirate feedback control system can be determinated. This transfer function model has a very simple structure, and can be used as a basis for the analysis and synthesis of the multirate sampling feedback control systems in the frequency domain. 展开更多
关键词 feedback control transfer functions multirate digital control systems computer control
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MEASURING OF COMPLEX STRUCTURE TRANSFER FUNCTION AND CALCULATING OF INNER SOUND FIELD
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作者 Chen Yuan Huang Qibai Shi Hanmin 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2005年第4期582-585,共4页
In order to measure complex structure transfer function and calculate inner sound field, transfer function of integration is mentioned. By establishing virtual system, transfer function of integration can be measured ... In order to measure complex structure transfer function and calculate inner sound field, transfer function of integration is mentioned. By establishing virtual system, transfer function of integration can be measured and the inner sound field can also be calculated. In the experiment, automobile body transfer function of integration is measured and experimental method of establishing virtual system is very valid. 展开更多
关键词 Complex structure Virtual system transfer function of integration
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Energy transfer in double plate system dynamics 被引量:2
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作者 Katica (Stevanovi) Hedrih 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2008年第3期331-344,共14页
The study of energy transfer between coupled subsystems in a hybrid system is very important for applications. This paper presents an analytical analysis of energy transfer between plates of a visco-elastically connec... The study of energy transfer between coupled subsystems in a hybrid system is very important for applications. This paper presents an analytical analysis of energy transfer between plates of a visco-elastically connected double-plate system in free transversal vibrations. The analytical analysis shows that the visco-elastic connection between plates is responsible for the appearance of two-frequency regime in the time function, which corresponds to one eigen amplitude function of one mode, and also that time functions of different vibration modes are uncoupled, but energy transfer between plates in one eigen mode appears. It was shown for each shape of vibrations. Series of the two Lyapunov exponents corresponding to the one eigen amplitude mode are expressed by using the energy of the corresponding eigen amplitude time component. 展开更多
关键词 Energy transfer between subsystems Doubleplate system Multifrequency transversal vibrations Analytical solution Rayleigh function of dissipation
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基于AMESim的集装箱翻转机液压系统设计与分析
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作者 史桢 王海滨 +2 位作者 李耀翔 冷峰 楚志勇 《机床与液压》 北大核心 2025年第1期209-216,共8页
为降低集装箱翻转机研制成本并提高其翻转作业效率,对集装箱翻转机的翻转机构液压系统展开研究。分析其机器结构和工作原理,并进行受力分析,设计翻转机构液压系统。通过AMESim仿真软件对该系统进行仿真分析,并利用自行研制的集装箱翻转... 为降低集装箱翻转机研制成本并提高其翻转作业效率,对集装箱翻转机的翻转机构液压系统展开研究。分析其机器结构和工作原理,并进行受力分析,设计翻转机构液压系统。通过AMESim仿真软件对该系统进行仿真分析,并利用自行研制的集装箱翻转机进行翻转作业试验。结果表明:机器两侧翻转液压缸受力大小相近,闭环液压控制系统工作性能优于开环液压系统,闭环液压控制系统频带带宽满足作业要求。机器两侧翻转液压缸受力大小近似相等,与仿真分析结果一致;无杆腔压力试验值偏高、有杆腔压力试验值偏低、无杆腔和有杆腔流量试验值均偏低,与仿真曲线具有良好的相关性和高度的拟合性。 展开更多
关键词 集装箱翻转机 液压控制系统 翻转液压缸载荷 AMESIM 系统传递函数
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双波段共口径消热差枪瞄物镜光学系统设计
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作者 白鑫如 蒋世磊 +2 位作者 弓旭航 蒋大成 冯江 《应用光学》 北大核心 2025年第1期32-40,共9页
为满足光电瞄准具昼夜合一、轻量化、稳定性优良的需求,本文设计了一款可见光和近红外双波段、共口径,且使用CMOS相机接收成像光束的共口径数码瞄准物镜。物镜光学系统设计波段为0.4μm~0.65μm和0.7μm~0.85μm,焦距为50 mm,F数1.4,系... 为满足光电瞄准具昼夜合一、轻量化、稳定性优良的需求,本文设计了一款可见光和近红外双波段、共口径,且使用CMOS相机接收成像光束的共口径数码瞄准物镜。物镜光学系统设计波段为0.4μm~0.65μm和0.7μm~0.85μm,焦距为50 mm,F数1.4,系统总长90 mm,系统在-40℃~+50℃温度范围内无热差影响,各波段畸变均小于0.04%,可见光波段在100 lp/mm处MTF>0.55,近红外波段在100 lp/mm处MTF>0.3。通过优化系统敏感面引起的像差,合理分配光焦度,降低了系统加工公差灵敏度和系统装配难度及成本。设计结果表明:系统均采用球面镜,结构简单、体积小、成本低、公差良好,能够实现在全工作温度范围内成像质量良好,具有一定的工程应用前景。 展开更多
关键词 共口径枪瞄物镜 消热差 公差灵敏度 调制传递函数 光学系统
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大气湍流对机载电视成像系统作用距离的影响
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作者 贠平平 侯利冰 +2 位作者 卜忠红 宋慧娟 李超 《激光与红外》 北大核心 2025年第1期91-96,共6页
大气湍流严重影响机载电视成像系统的成像质量。对目标和背景光学信号传输成像机理进行分析,建立了包含大气湍流效应的基于最小可分辨对比度(MRC)的电视成像系统作用距离模型。对大气湍流基本理论进行分析,分析得出适用于直升机载电视... 大气湍流严重影响机载电视成像系统的成像质量。对目标和背景光学信号传输成像机理进行分析,建立了包含大气湍流效应的基于最小可分辨对比度(MRC)的电视成像系统作用距离模型。对大气湍流基本理论进行分析,分析得出适用于直升机载电视成像系统的大气折射率结构常数,给出了大气相干直径计算方法,建立了大气湍流调制传递函数。以某型直升机载电视成像系统为例,对大气湍流效应对电视成像系统作用距离的影响进行仿真分析,仿真结果表明大气湍流效应使直升机载电视成像系统的作用距离性能严重下降。研究结果可为直升机载电视成像系统作用距离指标论证提供参考,提高指标论证准确度。 展开更多
关键词 大气湍流 大气相干直径 调制传递函数 机载电视成像系统 作用距离预测
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基于改进差分进化算法的系统辨识方法
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作者 吕证 陈博 +1 位作者 李章勇 秦对 《重庆邮电大学学报(自然科学版)》 北大核心 2025年第1期37-45,共9页
对于复杂控制系统,采用传统建模方法得到的被控对象模型,存在精度较低和收敛速度较慢等问题。针对该问题,提出了一种基于改进差分进化算法的系统辨识方法,通过采用变异率和交叉算子动态更新策略,并实时更新种群以及优化、进化终止条件,... 对于复杂控制系统,采用传统建模方法得到的被控对象模型,存在精度较低和收敛速度较慢等问题。针对该问题,提出了一种基于改进差分进化算法的系统辨识方法,通过采用变异率和交叉算子动态更新策略,并实时更新种群以及优化、进化终止条件,大幅度地提升了辨识模型的精度以及算法的收敛速度。与传统的最小二乘法、二阶加时滞模型法、差分进化算法以及遗传算法相比,提出的辨识方法在精度上分别提升了94.91%、40.11%、23.33%和8.48%。与传统遗传算法和差分进化算法相比,提出的方法在收敛速度上提升了近3.2倍。实验结果表明,提出的方法可以有效地克服干扰信号影响,得到精确的系统传递函数模型。 展开更多
关键词 系统辨识 改进差分进化算法 超声换能器 传递函数模型
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采用柔性支撑振镜抑制周扫光电侦察系统像移
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作者 曹佳乐 陈青山 +1 位作者 夏润秋 王艳林 《激光技术》 北大核心 2025年第1期28-32,共5页
为了抑制周扫光电侦察系统的像移,并降低虚警率,采用柔性支撑振镜进行高频像移补偿。使用柔性支撑结构代替轴承支撑结构,给出了补偿振镜传递函数模型,搭建了包括目标标靶、方位转台、像移补偿振镜等功能部件的柔性支撑振镜像移补偿效果... 为了抑制周扫光电侦察系统的像移,并降低虚警率,采用柔性支撑振镜进行高频像移补偿。使用柔性支撑结构代替轴承支撑结构,给出了补偿振镜传递函数模型,搭建了包括目标标靶、方位转台、像移补偿振镜等功能部件的柔性支撑振镜像移补偿效果测试系统。结果表明,像移补偿振镜摆扫频率大于105 Hz,匀速段时间大于5.5 ms,速度稳定性大于99.60%,探测器成像清晰,明显抑制像移,柔性支撑振镜可以满足周扫光电侦察系统高频像移补偿的需求。此研究对周扫光电侦察系统在高频成像探测时的像移补偿领域有一定的参考价值。 展开更多
关键词 成像系统 像移补偿 柔性支承结构 振镜传递函数
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Reduced Order H_∞/LTR Method for Aeroengine Control System 被引量:5
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作者 杨刚 孙健国 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2004年第3期129-135,共7页
This paper proposes a new loop recovery method to solve the reduced order problem of H∞/ LTR method. The resulted lower order controller shares almost the same performance and robustness as the original H ∞/LTR cont... This paper proposes a new loop recovery method to solve the reduced order problem of H∞/ LTR method. The resulted lower order controller shares almost the same performance and robustness as the original H ∞/LTR controller. Further more, this paper develops a new order reduction method: slow-fast mode order reduction (SFMOR) method. This order reduction method is particularly effective for those controllers whose modes can be divided into a slow part and a fast part according to their velocities. Application of these methods to a benchmark example and a certain turbofan engine is described. 展开更多
关键词 Control systems Mathematical models Problem solving Robustness (control systems) transfer functions Turbofan engines Velocity control Velocity measurement
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A Neuron-Oriented Programming System 被引量:3
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作者 李涛 《High Technology Letters》 EI CAS 2001年第1期70-73,共4页
A neruon-oriented programming system based on parallel neural information processing has been presented. With the neural programming system built upon 4~8 process elements(TMS C30), the system has thus provided users... A neruon-oriented programming system based on parallel neural information processing has been presented. With the neural programming system built upon 4~8 process elements(TMS C30), the system has thus provided users high speed, general purpose and large scale neural network application development platforms etc. 展开更多
关键词 Neural networks Parallel processing Programming system
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农地流转制度差异的实践逻辑与创新路径
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作者 梁伟 《西部论坛》 北大核心 2025年第1期112-124,共13页
区域差异是我国农地流转制度实践的重要特征,深入探析农地流转制度实践的区域差异,对于推动农地流转制度创新具有重要意义。基于“功能属性-治理结构”的分析框架,比较苏南Z县和湖北S县的农地流转制度实践,分析发现,乡村工业化水平和基... 区域差异是我国农地流转制度实践的重要特征,深入探析农地流转制度实践的区域差异,对于推动农地流转制度创新具有重要意义。基于“功能属性-治理结构”的分析框架,比较苏南Z县和湖北S县的农地流转制度实践,分析发现,乡村工业化水平和基层治理能力的差异导致了两地农地流转制度实践的差异。在苏南Z县,高度发达的乡村工业化加速了农业劳动力的非农转移,强化了农地流转制度提升农地资源配置效率的经济功能;良好的经济条件也为基层政府和村集体提供了充足的治理资源,形成了政社共治的农地流转治理格局。在湖北S县,非农产业难以提供充足的就业机会,农地流转制度仍需具有福利供给的保障功能;薄弱的经济基础也导致基层政府和村集体治理资源匮乏,农地流转在社区内自发进行,形成关系治理的农地流转治理格局。因此,东部发达地区的农地流转制度创新应通过规范市场降低农地流转风险,中西部地区的农地流转制度创新应在坚持村社本位的基础上充分发挥村集体的统筹作用。 展开更多
关键词 农地流转 制度差异 功能属性 治理结构 村集体 制度创新
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Analysis of Control Characteristic for the Drive System of Electric Transit Bus
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作者 张承宁 李红林 +1 位作者 孙逢春 张旺 《Journal of Beijing Institute of Technology》 EI CAS 2003年第3期302-306,共5页
The drive control system of the permanent magnetic direct current motor with the enhanced magnetism windings used in the electric transit bus is developed. The mathematics model of the drive control system for this mo... The drive control system of the permanent magnetic direct current motor with the enhanced magnetism windings used in the electric transit bus is developed. The mathematics model of the drive control system for this motor is established. The new mode that the added exiting magnetism field could be weakened and the speed of the motor could be controlled automatically is proposed and realized. The method of root locus design is applied to analyze the acceleration control characteristic. The results of simulation show that the new drive motor control system has extraordinary response characteristic and adjustable performance. Experiments of vehicle running show that the drive control system's antijamming ability is strong and the adjustable performance is fast and smooth, it can meet the demand of power characteristic very well. 展开更多
关键词 control characteristic electric transit bus enhanced magnetism motor drive system transfer function root trace
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A frequency-domain method for solving linear time delay systems with constant coefficients 被引量:1
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作者 Mengshi Jin Wei Chen +1 位作者 Hanwen Song Jian Xu 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2018年第4期781-791,共11页
In an active control system, time delay will occur due to processes such as signal acquisition and transmission, calculation,and actuation. Time delay systems are usually described by delay differential equations(DDE... In an active control system, time delay will occur due to processes such as signal acquisition and transmission, calculation,and actuation. Time delay systems are usually described by delay differential equations(DDEs). Since it is hard to obtain an analytical solution to a DDE, numerical solution is of necessity. This paper presents a frequency-domain method that uses a truncated transfer function to solve a class of DDEs. The theoretical transfer function is the sum of infinite items expressed in terms of poles and residues. The basic idea is to select the dominant poles and residues to truncate the transfer function,thus ensuring the validity of the solution while improving the efficiency of calculation. Meanwhile, the guideline of selecting these poles and residues is provided. Numerical simulations of both stable and unstable delayed systems are given to verify the proposed method, and the results are presented and analysed in detail. 展开更多
关键词 Time delay system Delay differential equation Approximate solution transfer function
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On the hydro-spectrum of deep wells and the response ability of well-aquifer system
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作者 简文彬 陈葆仁 刘淑芸 《Acta Seismologica Sinica(English Edition)》 CSCD 1995年第4期639-645,共7页
Onthehydro-spectrumofdeepwellsandtheresponseabilityofwell-aquifersystemWen-BinJIAN(简文彬);Bao-RenCHEN(陈葆仁)andS... Onthehydro-spectrumofdeepwellsandtheresponseabilityofwell-aquifersystemWen-BinJIAN(简文彬);Bao-RenCHEN(陈葆仁)andShu-YunLIU(刘淑芸)(De... 展开更多
关键词 transfer function well-aquifer system hydro-spectrum response ability
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数模—动模混合仿真系统的接口建模与稳定性分析
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作者 李振兴 贾倩薇 +1 位作者 林龙剑 冷凤 《现代电力》 北大核心 2024年第2期209-218,共10页
为满足现代电力系统实时仿真的发展需求,数模-动模混合仿真系统结合实时数字仿真和物理动态模拟仿真的优点,成为现代电力系统研究的重要仿真方法。接口系统是混合仿真系统设计中的核心与难点。为了深入分析混合仿真系统的稳定性,对接口... 为满足现代电力系统实时仿真的发展需求,数模-动模混合仿真系统结合实时数字仿真和物理动态模拟仿真的优点,成为现代电力系统研究的重要仿真方法。接口系统是混合仿真系统设计中的核心与难点。为了深入分析混合仿真系统的稳定性,对接口系统各个组成环节进行建模得到系统开环传递函数,分别根据劳斯判据和奈奎斯特判据研究开环传递函数中不同参数对系统稳定性的影响。理论推导表明接口系统中滤波器截止频率、接口延时和阻抗模拟比对系统的稳定性影响较大,并通过所搭建的混合仿真系统进行实验,实验结果表明不同参数对系统的稳定性影响与理论推导一致。 展开更多
关键词 电力系统实时仿真 开环传递函数 接口建模 稳定性分析
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基于阻尼系数灵敏度的风光电网动态交互分析与稳定提升方法 被引量:1
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作者 李生虎 陈东 +2 位作者 叶剑桥 齐楠 徐志雄 《电力系统保护与控制》 EI CSCD 北大核心 2024年第16期150-161,共12页
风电、光伏与同步发电机(synchronous generator,SG)间动态交互,影响电力系统稳定性。基于阻尼系数灵敏度,研究了风光并网电力系统动态交互过程与稳定提升方法。首先,基于线性化表达验证了风光机组对SG暂态响应存在影响。其次,建立电力... 风电、光伏与同步发电机(synchronous generator,SG)间动态交互,影响电力系统稳定性。基于阻尼系数灵敏度,研究了风光并网电力系统动态交互过程与稳定提升方法。首先,基于线性化表达验证了风光机组对SG暂态响应存在影响。其次,建立电力系统闭环传递函数模型,分析风光机组与SG间的动态交互过程。新定义风光机组向SG提供阻尼系数,以量化风光并网对电网振荡的影响。然后,提出阻尼系数对风光出力灵敏度的解析表达,作为内点法梯度信息,调整风光出力以改善电网稳定性。最后,仿真验证表明,调节风电(光伏)出力可提高光伏(风电)场站相关危险模式的阻尼,改善电网稳定性。以灵敏度作为梯度信息,可提高优化算法的计算效率与准确性,优化前后功角平均振幅分别为25.1589°、18.0165°。 展开更多
关键词 风光并网 低频振荡 阻尼转矩 传递函数 灵敏度
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