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Influence of acceleration stage electrode voltage on the performance of double-stage Hall effect thruster with adjustable zero magnetic point
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作者 陈龙 高维富 +5 位作者 崔作君 段萍 许雪松 阚子晨 檀聪琦 陈俊宇 《Plasma Science and Technology》 SCIE EI CAS CSCD 2024年第6期60-69,共10页
The configuration of electrode voltage and zero magnetic point position has a significant impact on the performance of the double-stage Hall effect thruster. A 2D-3V model is established based on the two-magnetic peak... The configuration of electrode voltage and zero magnetic point position has a significant impact on the performance of the double-stage Hall effect thruster. A 2D-3V model is established based on the two-magnetic peak type double-stage Hall thruster configuration, and a particle-in-cell simulation is carried out to investigate the influences of both acceleration electrode voltage value and zero magnetic point position on the thruster discharge characteristics and performances.The results indicate that increasing the acceleration voltage leads to a larger potential drop in the acceleration stage, allowing ions to gain higher energy, while electrons are easily absorbed by the intermediate electrode, resulting in a decrease in the anode current and ionization rate. When the acceleration voltage reaches 500 V, the thrust and efficiency are maximized, resulting in a 15%increase in efficiency. After the acceleration voltage exceeds 500 V, a potential barrier forms within the channel, leading to a decrease in thruster efficiency. Further study shows that as the second zero magnetic point moves towards the outlet of the channel, more electrons easily traverse the zero magnetic field region, participating in the ionization. The increase in the ionization rate leads to a gradual enhancement in both thrust and efficiency. 展开更多
关键词 Hall thruster particle-in-cell simulation intermediate electrode zero magnetic point
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Spatial variation law of vertical derivative zero points for potential field data 被引量:7
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作者 王万银 张功成 梁建设 《Applied Geophysics》 SCIE CSCD 2010年第3期197-209,292,共14页
In this paper we deduce the analytic solutions of the first- and second-order vertical derivative zero points for gravity anomalies in simple regular models with single, double, and multiple edges and analyze their sp... In this paper we deduce the analytic solutions of the first- and second-order vertical derivative zero points for gravity anomalies in simple regular models with single, double, and multiple edges and analyze their spatial variation. For another simple regular models where it is difficult to obtain the analytic expression of the zero point, we try to use the profile zero points to analyze the spatial variation. The test results show that the spatial variation laws of both first- and second-order vertical derivative zero points are almost the same but the second-order derivative zero point position is closer to the top surface edge of the geological bodies than the first-order vertical derivative and has a relatively high resolution. Moreover, with an increase in buried depth, for a single boundary model, the vertical derivative zero point location tends to move from the top surface edge to the outside of the buried body but finally converges to a fixed value. For a double boundary model, the vertical derivative zero point location tends to migrate from the top surface edge to the outside of the buried body. For multiple boundary models, the vertical derivative zero point location converges from the top surface edge to the outside of the buried body where some zero points coincide and finally vanish. Finally, the effectiveness and reliability of the proposed method is verified using real field data. 展开更多
关键词 vertical derivative zero point spatial variation law edge location
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ON THE EXISTENCE OF ZERO POINTS OF A CONTINUOUS FUNCTION 被引量:7
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作者 J.M. SorianoDepartamento de Andlisis Matematico, Facultad de Matemdticas, Universidad de Sevilla, Aptdo. 1160, Sevilla 41080, Spain 《Acta Mathematica Scientia》 SCIE CSCD 2002年第2期171-177,共7页
A sufficient condition is given to assert that a continuous mapping between Rm and Rn has a zero. The constructive proof of the result is based upon continuation methods and supplies the existence of a path leading to... A sufficient condition is given to assert that a continuous mapping between Rm and Rn has a zero. The constructive proof of the result is based upon continuation methods and supplies the existence of a path leading to the zero point. 展开更多
关键词 zero point continuation methods Banach fixed point theorem HOMOTOPY topological direct sum ISOMORPHISM k-contractive mapping
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ZEROS AND FIXED POINTS OF DIFFERENCE OPERATORS OF MEROMORPHIC FUNCTIONS 被引量:1
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作者 崔巍巍 杨连忠 《Acta Mathematica Scientia》 SCIE CSCD 2013年第3期773-780,共8页
Let f be a transcendental meromorphic function and △f(z) = f(z + 1) -- f(z) A number of results are proved concerning the existences of zeros and fixed points of Af(z) and △f(z)/f(z) when f(z) is of o... Let f be a transcendental meromorphic function and △f(z) = f(z + 1) -- f(z) A number of results are proved concerning the existences of zeros and fixed points of Af(z) and △f(z)/f(z) when f(z) is of order σ(f)=1. Examples show that some of the results are sharp. 展开更多
关键词 Entire functions meromorphic functions complex difference fixed points zeroS
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The ~3.6 to 3.7 M Paucity in Global Earthquake Frequency: Potential Coupling to Zero Point Fluctuation Force and Quantum Energies 被引量:1
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作者 David A. E. Vares Michael A. Persinger 《International Journal of Geosciences》 2013年第10期1321-1325,共5页
There has been protracted historical evidence of a relative paucity in the distribution frequency of global earthquakes within the M = 3.5 to 4.0 range. We observed a similar phenomenon for all recently recorded earth... There has been protracted historical evidence of a relative paucity in the distribution frequency of global earthquakes within the M = 3.5 to 4.0 range. We observed a similar phenomenon for all recently recorded earthquakes from January 2009 through August 2013. Frequency distributions with increments of M = 0.1 verified the trough of the diminished incidence to be between M = 3.6 and 3.7 with an abrupt increase between M = 3.9 and 4.0. The calculated equivalent photon wavelength for the energies associated with M = 3.6 approaches Planck’s Length while the related time increment is the cutoff frequency for the Zero Point Fluctuation force coupled to gravity. The conspicuous congruence between Planck’s time and length and the lower than expected frequency based upon Gaussian assumptions of distribution for the discrete band of energy associated with this magnitude range of earthquakes suggests a conduit may exist between intrinsic features of Planck space-time and geophysical processes. The existence of such a connection would encourage alternative explanations for sun-seismic activities as due to solar instabilities. Instead, it may reflect influence upon both from alterations in the structure of space being traversed by the solar system as it moves through the galaxy. 展开更多
关键词 Low MAGNITUDE Earthquake Frequency GAUSSIAN Distribution Planck’s Length Energy zero point FLUCTUATION Frequencies QUANTUM GEOPHYSICAL Effects
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On the Cosmical Zero Point Energy Density 被引量:1
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作者 Bo Lehnert 《Journal of Modern Physics》 2016年第10期1112-1119,共8页
The frequency spectrum of the cosmical Zero Point Energy (ZPE) and its total density are so far unknown in their details. In the present complementary investigation, a revised theory forms the basis for studies of thi... The frequency spectrum of the cosmical Zero Point Energy (ZPE) and its total density are so far unknown in their details. In the present complementary investigation, a revised theory forms the basis for studies of this concept in two respects. It first applies to the observable universe considered as an entity, as well as to included subregions such as the galaxies with supermassive black holes. Second, experiments are proposed on the maximum Casimir force arising between two metal plates of different materials and with a vanishing air gap in their spacing. This serves the purpose of making an indirect determination of the ZPE energy density in the laboratory, i.e. at the Earth’s orbit. The ZPE energy density is interpreted as dark matter density and its pressure gradient as dark energy force density. 展开更多
关键词 zero point Energy Casimir Force Dark Matter Dark Energy
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The Isoelectric Point and the Points of Zero Charge of Fe-Al-Mg Hydrotalcite-like Compounds
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作者 DongXiangLI WanGuoHOU +2 位作者 ShuPingLI MingTuHAO GaoYongZHANG 《Chinese Chemical Letters》 SCIE CAS CSCD 2004年第2期224-227,共4页
The relation of the isoelectric point (IEP) and the point of zero net charge (PZNC) of the hydrotalcite-like compounds was discussed. It was found that the IEP does not equal to the PZNC and the IEP is higher than th... The relation of the isoelectric point (IEP) and the point of zero net charge (PZNC) of the hydrotalcite-like compounds was discussed. It was found that the IEP does not equal to the PZNC and the IEP is higher than the PZNC. The structural positive charges existing in the HTlc, which cause the difference between the IEP and the PZNC. The effects of the structural positive charges of the HTlc on its IEP and PZNC are the same as the specific adsorption of metal cations. 展开更多
关键词 Isoelectric point points of zero charge potentiometric titration hydrotalcite-like compounds.
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Zero Point of Charge of Organo—Mineral Complexes
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作者 M.T.ANSARI XUJIAN-MING 《Pedosphere》 SCIE CAS CSCD 1994年第3期269-276,共8页
Five soil samples collected from China and two soil samples from Pakistan with widely different origin and characteristics were used to study the zero point of charge (ZPC) of soil colloids. The results showed that th... Five soil samples collected from China and two soil samples from Pakistan with widely different origin and characteristics were used to study the zero point of charge (ZPC) of soil colloids. The results showed that the value of zero point of charge of H-clay complexes was lower than that of H-clays in all the samples.Natural clay complexes had the highest ZPC as compared to H-clay complex and H-clay in alfisol, closer to H-clays rather than H-clay complexes in oxisol and udult. The delta value of ZPT (zero point of titration)to ZPC was higher in H-clay complexes than in H-clays. 展开更多
关键词 organo-mineral complexes soil colloids zero point of charge
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Some Consequences of Zero Point Energy
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作者 Bo Lehnert 《Journal of Electromagnetic Analysis and Applications》 2014年第10期319-327,共9页
Both theory and experiments indicate that the vacuum is not a state of empty space, but is populated by electromagnetic fluctuations at a lowest nonzero level, the Zero Point Energy (ZPE). This debouches into consider... Both theory and experiments indicate that the vacuum is not a state of empty space, but is populated by electromagnetic fluctuations at a lowest nonzero level, the Zero Point Energy (ZPE). This debouches into considerable changes of fundamental physics, as shown by a revised quantum electrodynamic theory (RQED) applied to elementary particles, and by a revised ZPE frequency spectrum applied to the expanding universe. The Standard Model based on a vacuum state of empty space is thus replaced by RQED, thereby resulting in massive elementary particles from the beginning, independently of the theory by Higgs. Also the basic properties of the Higgs-like particle detected at CERN can be reproduced by RQED. It further leads to new fundamental results beyond the theories by Dirac and Higgs, such as to a deduced value of the elementary net charge, magnetic confinement of charged particle configurations, intrinsic local particle charges, photon spin with a very small but nonzero photon rest mass, and needle-like particle-wave properties which contribute to the understanding of the photoelectric effect and two-slit experiments. The real macroscopic pressure due to the revised ZPE frequency distribution further influences the dynamics of the expanding universe, by the ZPE photon pressure gradient acting as dark energy, and the ZPE photon energy density acting as dark matter. This results in a model being consistent with the observed scale, the rate of expansion, and the stability of a flat expanding observable universe. 展开更多
关键词 zero point ENERGY Quantum ELECTRODYNAMICS Standard Model and Beyond EXPANDING UNIVERSE DARK ENERGY DARK MATTER
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Mode Interaction at a Triple Zero Point of O(2) symmetric Nonlinear Systems with Two Parameters
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作者 吴微 孟繁友 《Northeastern Mathematical Journal》 CSCD 2000年第1期10-20,共11页
We consider a triple zero point of nonlinear equations with O(2 symmetry, where the Jacobian has a zero eigenvalue of geometric multiplicity one and algebraic multiplicity three. We show that this triple zero point e... We consider a triple zero point of nonlinear equations with O(2 symmetry, where the Jacobian has a zero eigenvalue of geometric multiplicity one and algebraic multiplicity three. We show that this triple zero point exhibits a new bifurcation phenomenon, that is, a mode interaction of the following three paths: bifurcation points from steady states, steady states and rotating waves to standing waves, rotating waves and modulated rotating waves respectively. 展开更多
关键词 mode interaction BIFURCATION triple zero point O(2) symmetry nonlinear system
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Zero Point Energy Effects on Quantum Electrodynamics
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作者 Bo Lehnert 《Journal of Modern Physics》 2015年第4期448-452,共5页
The vacuum is not a state of empty space, but is populated by electromagnetic fluctuations at a lowest nonzero level, the Zero Point Energy (ZPE). As distinguished from conventional theories, such as that of the Stand... The vacuum is not a state of empty space, but is populated by electromagnetic fluctuations at a lowest nonzero level, the Zero Point Energy (ZPE). As distinguished from conventional theories, such as that of the Standard Model, the present revised quantum electrodynamic theory (RQED) includes the ZPE in its field equations. This leads to new results far beyond those obtained from conventional theories such as those by Dirac and Higgs. Thus, the present theory results in massive elementary particles from the beginning, being independent of the theory by Higgs. This paper describes the background and results of RQED, summarizing the weak points of conventional theories, the unification of included fundamental concepts, the present basic field equations, new obtained results, and special points of experimental support. In other words, the new points stressed in this paper are in particular the relation between a nonzero electric field divergence in the vacuum and the ZPE, and a number of new experimentally supported results due to a nonzero ZPE energy density in the same state. 展开更多
关键词 zero point Energy QUANTUM ELECTRODYNAMICS Standard Model and BEYOND
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On the Problem of Zero Point Distribution of Integer Functions
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作者 Yang Hesong 《International Journal of Technology Management》 2016年第6期24-25,共2页
Abstract. In this paper, the following integer function is discussed.
关键词 INTEGER FUNCTIONS zero pointS LEVEL
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A Measure System of Zero Moment Point Using Wearable Inertial Sensors
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作者 Xianggang Zhang Hao Wang +3 位作者 Yuliang Shi Changjun Fu Huiqin Wang Guoyu Wang 《China Communications》 SCIE CSCD 2016年第5期16-27,共12页
Keeping balance is the premise of human walking. ZMP(zero moment point) is a point where total torque achieves balance. It is an important evaluation parameter of balance ability in walking, since it can be used to be... Keeping balance is the premise of human walking. ZMP(zero moment point) is a point where total torque achieves balance. It is an important evaluation parameter of balance ability in walking, since it can be used to better reflect the dynamic balance during walking. ZMP can be used in many applications, such as medical rehabilitation, disease diagnosis, treatment and etc. In this paper, wearable inertial sensors system based on MEMS is used to measure ZMP(zero moment point) during walking, which is cheap, convenient, and free from the restriction of lab. Our wearable ZMP measurement system consists of inertial measurement subsystem and PC real-time monitoring station. Inertial measurement subsystem includes 9-axis inertial sensing nodes, the body communication network and the central node. Inertial sensing nodes are mounted on different parts of the body to collect body posture information in real-time, and then the best estimation of current posture are obtained by Kalman filter. The data from sensors is aggregated to the central node through the CAN bus, and then ZMP is calculated. Finally, it can be showed in the PC monitoring station. Experiments prove the system can achieve real-time ZMP detection during walking. 展开更多
关键词 zero moment point body balance inertial measurement quaternion Kalman filter
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Superconductivity, Superfluidity and Zero-Point Oscillations
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作者 Boris V. Vasiliev 《Journal of Modern Physics》 2018年第3期315-319,共5页
It is shown that both super phenomena-superconductivity and superfluidity are based on the same mechanism of streamline of zero-point oscillations. Proof of this is the agreement of obtained theoretical estimations wi... It is shown that both super phenomena-superconductivity and superfluidity are based on the same mechanism of streamline of zero-point oscillations. Proof of this is the agreement of obtained theoretical estimations with measured data. 展开更多
关键词 SUPERCONDUCTIVITY SUPERFLUIDITY zero-point OSCILLATIONS
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An Analogy between the Properties of “Dark Energy” and Physical Vacuum Consisting of Quantum Harmonic Oscillators Characterized by Zero-Point Energy
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作者 Liudmila B. Boldyreva 《Journal of Modern Physics》 2019年第1期20-34,共15页
In quantum field theory, the physical vacuum, free from magnetic and electric fields (without regard to gravitational energy), is defined not as an empty space but as the ground state of the field consisting of quantu... In quantum field theory, the physical vacuum, free from magnetic and electric fields (without regard to gravitational energy), is defined not as an empty space but as the ground state of the field consisting of quantum harmonic oscillators (QHOs) characterized by zero-point energy. The aim of this work is to show that such physical vacuum may possess the properties similar to the properties of dark energy: the positive density, the negative pressure, and the possibility of so-called accelerated expansion. In the model discussed, the mass of QHOs determines the positive density of dark energy. The observed electric polarization of physical vacuum in an electric field means the existence of electric dipole moment of QHO, which, in turn, suggests the existence inside the QHO of a repulsive force between unlike charges compensating the attractive Coulomb force between the charges. The existence of such repulsive force may be treated as the existence of omniradial tensions inside every QHO. In terms of hydrodynamics, it means that the vacuum with this property may be regarded as a medium with negative pressure. The electric dipole-dipole interaction of QHOs under some condition may result in the expansion of physical vacuum consisting of QHOs. It is shown also that the physical vacuum consisting of QHOs is a luminiferous medium, and based on this concept the conditions are discussed for the emergence of invisiblity of any objects (in particular, dark matter). The existence of luminiferous medium does not contradict the second postulate of special relativity (the principle of constancy of the velocity of light in inertial systems), if to take into account the interaction of photons with QHOs and with virtual photons (the virtual particles pairs) created by quantum entities that constitute the inertial systems. 展开更多
关键词 DARK ENERGY DARK MATTER zero-point ENERGY Quantum Harmonic Oscillator COSMIC Microwave Background
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基于零点有效缺口应力的薄板焊接接头疲劳评估
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作者 舒伟 高静坤 +3 位作者 李海峰 邓彩艳 刘强 龚宝明 《焊接学报》 EI CAS CSCD 北大核心 2024年第6期121-128,共8页
文中采用零点有效缺口应力进行了薄板焊接接头的疲劳评估研究.该方法综合考虑整体结构应力以及缺口根部到零点位置的非线性峰值应力的影响,以临界距离法和零点结构应力法为基础,将零点应力位置作为缺口对结构疲劳影响的临界距离对焊接... 文中采用零点有效缺口应力进行了薄板焊接接头的疲劳评估研究.该方法综合考虑整体结构应力以及缺口根部到零点位置的非线性峰值应力的影响,以临界距离法和零点结构应力法为基础,将零点应力位置作为缺口对结构疲劳影响的临界距离对焊接结构进行疲劳强度评估.通过对两种不同类型的焊接接头试样(T形单面焊接头和不同厚度组合搭接接头)的疲劳试验结果进行拟合.结果表明,在对焊根失效的试样进行疲劳评估时,焊根位置不同截面应力线性化之后得到零点有效缺口应力存在较大差异;其中,焊脚截面应力线性化得到的S-N曲线分散带宽度最小;再者,同时考虑焊趾和焊根失效的零点有效缺口应力S-N曲线,与分别考虑焊趾或焊根失效的零点有效缺口应力S-N曲线分散带相差不大,证明该方法可同时用于焊接接头焊趾和焊根疲劳评估. 展开更多
关键词 零点有效缺口应力 焊接接头 疲劳评估
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单位圆内高阶非齐次微分方程复振荡与解及其任意阶导数的不动点
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作者 陈玉 邓冠铁 《应用数学》 北大核心 2024年第4期1154-1162,共9页
本文研究一类单位圆内有穷迭代级解析系数的高阶非齐次线性微分方程的复振荡与解及其任意阶导数的不动点问题,得到解的迭代增长级,迭代级零点收敛指数的更精细的估计,并得到解的不动点与解的任意阶导数的不动点分布的精确估计.所得结果... 本文研究一类单位圆内有穷迭代级解析系数的高阶非齐次线性微分方程的复振荡与解及其任意阶导数的不动点问题,得到解的迭代增长级,迭代级零点收敛指数的更精细的估计,并得到解的不动点与解的任意阶导数的不动点分布的精确估计.所得结果是已有相关结果的推广. 展开更多
关键词 微分方程 解析函数 单位圆 零点收敛指数 不动点
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应用于半导体激光器的高精度温控系统设计
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作者 叶茂 杜恩斯 +1 位作者 王秋玮 赵毅强 《红外与激光工程》 EI CSCD 北大核心 2024年第4期67-77,共11页
面向半导体激光器温控系统的高精度、高速与高集成化的需求,设计了一款高精度、快速响应、高集成化、低成本的数模混合架构温控系统。该系统以FPGA为控制核心,硬件部分包括由三线制惠斯通电桥、仪表放大器、模数转换器组成的温度信号采... 面向半导体激光器温控系统的高精度、高速与高集成化的需求,设计了一款高精度、快速响应、高集成化、低成本的数模混合架构温控系统。该系统以FPGA为控制核心,硬件部分包括由三线制惠斯通电桥、仪表放大器、模数转换器组成的温度信号采集与调理模块,全桥降压电路驱动模块,热电制冷器模块等。针对热敏电阻和电桥的非线性误差,提出了一种可变控温零点的温度信号调理方法,该方法基于迭代与多目标最优化算法,提高了控温精度,同时降低了仪表放大器与模数转换器的指标要求,从而降低了系统成本。针对温度滞后大、延迟高的特点,控温策略采用了抗饱和积分的PID(AWPID)自动控制方法,从而降低超调,加快收敛速度。测试结果表明,该温控系统在-45~75℃的温度范围内,实现了±0.02℃的控温精度,相较于固定控温零点的温控系统最大0.1951℃的控温精度提高了89.7%。与传统PID控制算法相比,AWPID控制算法将超调从9.13%降低到1.5%,将稳定时间从41 s降低到30 s。稳定性测试表明,该温控系统能够在长时间内保持±0.02℃的控温精度,满足稳定性要求。该系统具有高精度、快速响应、高集成化、低成本的特点,为半导体激光器的复杂应用场景提供了高精度的温度保障。 展开更多
关键词 半导体激光器 高精度温度控制 可变控温零点 最优化算法 抗饱和积分PID
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一种适用三电平并联系统的虚拟矢量调制策略
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作者 杜燕 杨世友 +2 位作者 胡军龙 杨向真 苏建徽 《中国电机工程学报》 EI CSCD 北大核心 2024年第21期8629-8641,I0025,共14页
直流侧中点电位平衡和零序环流抑制是保证三电平逆变器并联系统正常运行的重要问题,然而基于冗余小矢量对调节的环流抑制方案进一步增加空间矢量脉宽调制(space vector pulse width modulation,SVPWM)中点电流无法对称消除的场景,加剧... 直流侧中点电位平衡和零序环流抑制是保证三电平逆变器并联系统正常运行的重要问题,然而基于冗余小矢量对调节的环流抑制方案进一步增加空间矢量脉宽调制(space vector pulse width modulation,SVPWM)中点电流无法对称消除的场景,加剧双机系统中点电位不平衡程度。该文基于虚拟矢量合成思路,提出一种满足零序环流抑制和中点电位平衡需求的双机虚拟矢量调制方法。该方法重新定义虚拟中矢量,通过缩短中矢量作用时间和增加参与合成的对称冗余小矢量以减少中点电流不平衡场景;分析不同扇区不同控制目标下虚拟矢量合成规则,利用相占空比法优化虚拟矢量的作用顺序,减少矢量合成过程中的开关次数。与传统SVPWM策略下中点电压变化量的对比分析表明,所提方法能够削弱环流抑制和中点电位平衡的耦合关系。最后,利用Starsim平台实验验证该策略的有效性。 展开更多
关键词 三电平并联系统 虚拟矢量 零序环流 中点电位平衡 相占空比法 开关次数
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一种求解包含问题的算法研究
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作者 杨军 李飞艳 《咸阳师范学院学报》 2024年第2期1-4,共4页
一种实希尔伯特空间中求解包含问题的算法被提出,所提出的算法基于向前向后方法、压缩方法、惯性方法和无需搜索的自适应步长。算法的特点为迭代中多次使用惯性加速方法,且自适应步长随着迭代次数增加可能增大。在包含问题解集非空、一... 一种实希尔伯特空间中求解包含问题的算法被提出,所提出的算法基于向前向后方法、压缩方法、惯性方法和无需搜索的自适应步长。算法的特点为迭代中多次使用惯性加速方法,且自适应步长随着迭代次数增加可能增大。在包含问题解集非空、一个映射极大单调、另一个映射单调且利普希茨连续的假设下,算法的强收敛性被证明。 展开更多
关键词 包含问题 向前向后方法 零点
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