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过取样△∑调制技术(一)──过取样AD/DA变换的基本概念── 被引量:2
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作者 邹家禄 骆立俊 《电声技术》 北大核心 1994年第11期32-38,共7页
过取样AD/DA变换(oversampledAD/DAConverter)作为一种电路设计技术,已经迎来了一个新的发展时期,该技术使用了△调制和△∑调制这些过去大家都很熟悉的优选电路,本文将说明这一新变换技术的原理,... 过取样AD/DA变换(oversampledAD/DAConverter)作为一种电路设计技术,已经迎来了一个新的发展时期,该技术使用了△调制和△∑调制这些过去大家都很熟悉的优选电路,本文将说明这一新变换技术的原理,传统的AD/DA变换的极限范围,及它对大规模LSI设计的影响。过取样方式增加了数字处理的比重,减轻了模拟电路的负担,适应了VLSI发展的要求。 展开更多
关键词 过取样方式 调制 △∑调制 AD/DA变换
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过取样△Σ调制技术(二上)──△调制方式── 被引量:1
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作者 邹家禄 骆立俊 《电声技术》 北大核心 1994年第12期33-36,共4页
过取样△Σ调制技术(二上)──△调制方式──东南大学邹家禄,骆立俊一、前言在上一讲中,我们已经原理性他说明了过取样技术的优点。通过使取样频率f_s远比信号频率f_R高的办法,提高S/N,克服混叠噪声,实现高分辨力A/... 过取样△Σ调制技术(二上)──△调制方式──东南大学邹家禄,骆立俊一、前言在上一讲中,我们已经原理性他说明了过取样技术的优点。通过使取样频率f_s远比信号频率f_R高的办法,提高S/N,克服混叠噪声,实现高分辨力A/D变换器,这是过取样技术在原理上的... 展开更多
关键词 过取样方式 △∑调制 调制 调制方式
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用于D类放大器的ΔΣ调制器系统分析与设计 被引量:5
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作者 徐景 莫亭亭 +1 位作者 方乐章 刘程斌 《微电子学与计算机》 CSCD 北大核心 2008年第2期164-167,共4页
D类放大器具有效率高、功耗低的优点,已逐渐被应用到音频领域。为了克服传统D类放大器的内在缺陷,引入了ΔΣ调制技术以及闭环特性。但由于ΔΣ调制技术的系统设计对整个放大器非常重要,而且设计方法较复杂,因此需要借助于Matlab工具。... D类放大器具有效率高、功耗低的优点,已逐渐被应用到音频领域。为了克服传统D类放大器的内在缺陷,引入了ΔΣ调制技术以及闭环特性。但由于ΔΣ调制技术的系统设计对整个放大器非常重要,而且设计方法较复杂,因此需要借助于Matlab工具。分析了ΔΣ调制技术对D类放大器的非线性、噪声和EMI等性能的改善,对几种高阶ΔΣ调制器结构进行比较分析,最后制定详细的系统设计方法、步骤,并用Matlab工具进行系统建模与仿真。通过仿真结果,验证了设计系统的有效性,从而为实际电路设计提供基础。 展开更多
关键词 D类放大器 △∑调制 SIMULINK
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S类功放的频率可调带通ΔΣ调制器研究与实现 被引量:4
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作者 周强 朱蕾 陈江 《电子技术应用》 北大核心 2014年第6期103-105,108,共4页
S类射频功率放大器同时具有高效率和高线性特性,适合在全数字发信机中应用。但需要将任意输入的射频信号转换为两电平脉冲调制信号,带通增量求和(ΔΣ)调制才可以很好地实现上述功能。为实现S类功放的宽频带工作,带通ΔΣ调制器的中心... S类射频功率放大器同时具有高效率和高线性特性,适合在全数字发信机中应用。但需要将任意输入的射频信号转换为两电平脉冲调制信号,带通增量求和(ΔΣ)调制才可以很好地实现上述功能。为实现S类功放的宽频带工作,带通ΔΣ调制器的中心频率必须实现与输入信号频率的实时跟随。通过对ΔΣ调制算法的研究,提出了一种频率可调带通ΔΣ调制器的设计方法,并利用Matlab软件和FPGA对设计的调制器分别进行了仿真和实验验证。验证结果证明了该设计方法的可行性和有效性。 展开更多
关键词 射频功率放大器 模拟功放 S类功放 带通△∑调制 频率可调
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Regarding the Regulatory Sandbox Route and Mechanism for Governance of Artificial Intelligence
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作者 Ye Xuanhan 《科技与法律(中英文)》 2024年第5期136-148,共13页
The main challenge in AI governance today is striking a balance between controlling AI dangers and fostering AI innovation.Regulators in a number of nations have progressively extended the regulatory sandbox,which was... The main challenge in AI governance today is striking a balance between controlling AI dangers and fostering AI innovation.Regulators in a number of nations have progressively extended the regulatory sandbox,which was first implemented in the banking sector,to AI governance in an effort to reduce the conflict between regulation and innovation.The AI regulatory sandbox is a new and feasible route for AI governance in China that not only helps to manage the risks of technology application but also prevents inhibiting AI innovation.It keeps inventors'trial-and-error tolerance space inside the regulatory purview while offering a controlled setting for the development and testing of novel AI that hasn't yet been put on the market.By providing full-cycle governance of AI with the principles of agility and inclusive prudence,the regulatory sandbox offers an alternative to the conventional top-down hard regulation,expost regulation,and tight regulation.However,the current system also has inherent limitations and practical obstacles that need to be overcome by a more rational and effective approach.To achieve its positive impact on AI governance,the AI regulatory sandbox system should build and improve the access and exit mechanism,the coordination mechanism between the sandbox and personal information protection,and the mechanisms of exemption,disclosure,and communication. 展开更多
关键词 artificial intelligence governance regulatory sandbox agile regulation inclusive prudential regulation access and exit mechanism coordination mechanism
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一种新型频率合成器的实现 被引量:3
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作者 鄢华浩 王枚 赵利 《现代电子技术》 2004年第5期10-12,15,共4页
小数分频技术解决了锁相环频率合成器中的频率分辨率和转换时间的矛盾 ,但是却引入了严重的相位噪声 ,传统的相位补偿方法由于对 A/ D等数字器件的要求很高并具有滞后性实现难度较大。 ΔΣ调制器对噪声具有整形的功能 ,因而将多阶的 ... 小数分频技术解决了锁相环频率合成器中的频率分辨率和转换时间的矛盾 ,但是却引入了严重的相位噪声 ,传统的相位补偿方法由于对 A/ D等数字器件的要求很高并具有滞后性实现难度较大。 ΔΣ调制器对噪声具有整形的功能 ,因而将多阶的 ΔΣ调制器用于小数分频合成器中可以很好地解决他的相位噪声的问题 ,大大促进了小数分频技术的发展和应用。文章最后给出了在 GHz量级上实现的这种新型小数分频合成器的应用电路 。 展开更多
关键词 小数分频 相位噪声 △∑调制 A/D
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五阶过取样18bitΔΣADC—AD1879的分析 被引量:1
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作者 骆立俊 邹家 《电声技术》 北大核心 1996年第4期22-28,共7页
本文讨论了采用五阶过取样1bitΔΣ调制系统和疏值滤波器实现的18比特ADC芯片AD1879分析和设计方法,并给出了分析结果。
关键词 △∑调制 过取样 调制 ADC-AD1879
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高性能正弦音频信号发生器
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作者 骆立俊 邹家禄 《现代雷达》 CSCD 1996年第1期32-38,共7页
过取样△∑调制A/D、D/A技术已广泛用于移动通信、数字音响等领域,其中过取样△∑调制D/A变换技术可以用来产生高性能的正弦音频信号。高性能的正弦音频信号发生器可以精确地控制信号的频率和幅度,在音频范围内是稳定的,对... 过取样△∑调制A/D、D/A技术已广泛用于移动通信、数字音响等领域,其中过取样△∑调制D/A变换技术可以用来产生高性能的正弦音频信号。高性能的正弦音频信号发生器可以精确地控制信号的频率和幅度,在音频范围内是稳定的,对应的动态范围可以超过80dB。 展开更多
关键词 过取样 信号发生器 音频范围 △∑调制
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超声电机驱动信号源的ASIC设计
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作者 刘嫣 叶泽刚 《陕西科技大学学报(自然科学版)》 2008年第4期96-99,共4页
针对目前超声电机(Ultrasonic Motor,USM)驱动技术的研究现状以及USM驱动电路集成化、一体化、小型化的发展方向,提出了USM驱动信号源的ASIC(application-specific integrated circuit)解决方案.方案设计中采用了改进的直接数字频率合成... 针对目前超声电机(Ultrasonic Motor,USM)驱动技术的研究现状以及USM驱动电路集成化、一体化、小型化的发展方向,提出了USM驱动信号源的ASIC(application-specific integrated circuit)解决方案.方案设计中采用了改进的直接数字频率合成(Direct Digital Synthesis)技术和过采样调制技术,解决了传统DDS中存在的一些问题,并利用Candenc IC设计软件建立了USM的电学模型和仿真验证平台,仿真结果验证了方案的可行性与正确性. 展开更多
关键词 直接数字频率合成 △∑调制 过采样 低通滤波
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Microstructure and mechanical properties of TiN/TiAlN multilayer coatings deposited by arc ion plating with separate targets 被引量:13
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作者 魏永强 李春伟 +2 位作者 巩春志 田修波 杨士勤 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2011年第5期1068-1073,共6页
TiN/TiAlN multilayer coatings were prepared by arc ion plating with separate targets. In order to decrease the unfavorable macroparticles, a straight magnetized filter was used for the low melting aluminium target. Th... TiN/TiAlN multilayer coatings were prepared by arc ion plating with separate targets. In order to decrease the unfavorable macroparticles, a straight magnetized filter was used for the low melting aluminium target. The results show that the output plasmas of titanium target without filter and aluminium target with filter reach the substrate with the same order of magnitude. Meanwhile, the number of macropartieles in TiN/TiAlN multilayer coatings deposited with separate targets is only 1/10-1/3 of that deposited with alloy target reported in literature. Al atom addition may lead to the decrease of peak at (200) lattice plane and strengthening of peak at (111) and (220) lattice planes. The measured hardness of TiN/TiAlN multilayer coatings accords with the mixture principle and the maximum hardness is HV2495. The adhesion strength reaches 75 N. 展开更多
关键词 arc ion plating TiN/TiAlN coatings M2 high speed steel MACROPARTICLES HARDNESS bilayer modulation
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A 5mW 1.8V Low Over-Sampling Ratio ΣΔ Modulator with 81dB Dynamic Range 被引量:2
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作者 徐栋麟 赵晖 +2 位作者 王照钢 任俊彦 闵昊 《Journal of Semiconductors》 EI CAS CSCD 北大核心 2004年第1期12-18,共7页
This work demonstrates that the ΣΔ modulator with a low oversampling ratio is a viable option for the high-resolution digitization in a low-voltage environment.Low power dissipation is achieved by designing a low-OS... This work demonstrates that the ΣΔ modulator with a low oversampling ratio is a viable option for the high-resolution digitization in a low-voltage environment.Low power dissipation is achieved by designing a low-OSR modulator based on differential cascade architecture,while large signal swing maintained to achieve a high dynamic range in the low-voltage environment.Operating from a voltage supply of 1.8V,the sixth-order cascade modulator at a sampling frequency of 4-MHz with an OSR of 24 achieves a dynamic range of 81dB for a 80-kHz test signal,while dissipating only 5mW. 展开更多
关键词 ∑△ modulator low over sampling ratio low power low voltage
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ANALYSIS OF UN-COINCIDE COORDINATE ERROR IN SINGLE-AXIS ROTATING FIBER OPTIC STRAP-DOWN INERTIAL NAVIGATION SYSTEM 被引量:3
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作者 张玲 赖际舟 +1 位作者 刘建业 吕品 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI 2011年第2期199-205,共7页
The un-coincide coordinate error in the single-axis rotating fiber optic strap-down inertial navigation system(SINS) is analyzed. Firstly, a rotating modulation technology is presented for SINS. The method provides ... The un-coincide coordinate error in the single-axis rotating fiber optic strap-down inertial navigation system(SINS) is analyzed. Firstly, a rotating modulation technology is presented for SINS. The method provides the enhanced property of SINS when using the same-leveled inertial measurement units. Then, the rotating struc- ture modification is derived and augmented to resolve the un-modulated error-accumulated problem. As the insuf- ficient machine processing, the horizontal and the vertical errors on the machine surface are inevitable, and the in- volved coordinates are difficult to get the exact coincident. So, two major kinds of coordinate situation are stud- ied. The equivalent error models on gyro and acceleration outputs are built for each situation, and the impact is analyzed for compensation. The part of attitude and position error models caused by the built angle-rate error is established to calculate the un-eoincident impact. Considering these conditions of different gyro accuracy and mo- tion states simultaneously, numerical simulations are implemented. Results indicate that the SINS modulation ac- curacy is seriously affected by the combined factors on gyro accuracy and motion conditions. 展开更多
关键词 rotational molding modulation machine processing surface horizontal and vertical error un-coinci-dent impact
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Pulse Quick Charger of Electric Vehicle 被引量:3
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作者 张承宁 吴兵峰 +1 位作者 孙逢春 张旺 《Journal of Beijing Institute of Technology》 EI CAS 2002年第3期240-245,共6页
In order to improve the charging efficiency of lead acid battery, shorten the charging time and avoid the battery polarization, a new charging method was put forward. Based on the analyzed results of charging charact... In order to improve the charging efficiency of lead acid battery, shorten the charging time and avoid the battery polarization, a new charging method was put forward. Based on the analyzed results of charging characteristic of lead acid battery, a pulse quick charger is designed to adjust the charging current pulse’s amplitude and pulse width automatically stage by stage according to the measured battery voltage and feedback current. Compared with other kinds of quick chargers, it has such characteristics as shorter charging time, higher charging efficiency and lower temperature increasing during the charging process. As a result, the battery polarization is reduced efficiently. 展开更多
关键词 pulse quick charger lead acid battery electric vehicle
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A High-Performance Silicon Electro-Optic Phase Modulator with a Triple MOS Capacitor 被引量:2
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作者 黄北举 陈弘达 +2 位作者 刘金彬 顾明 刘海军 《Journal of Semiconductors》 EI CAS CSCD 北大核心 2006年第12期2089-2093,共5页
We propose and analyze a novel Si-based electro-optic modulator with an improved metal-oxide-semiconductor (MOS) capacitor configuration integrated into silicon-on-insulator (SOl). Three gate-oxide layers embedded... We propose and analyze a novel Si-based electro-optic modulator with an improved metal-oxide-semiconductor (MOS) capacitor configuration integrated into silicon-on-insulator (SOl). Three gate-oxide layers embedded in the silicon waveguide constitute a triple MOS capacitor structure, which boosts the modulation efficiency compared with a single MOS capacitor. The simulation results demonstrate that the Vπ Lπ product is 2. 4V · cm. The rise time and fall time of the proposed device are calculated to be 80 and 40ps from the transient response curve, respectively,indicating a bandwidth of 8GHz. The phase shift efficiency and bandwidth can be enhanced by rib width scaling. 展开更多
关键词 carrier accumulation plasma dispersion effect electro-optic phase modulator METAL-OXIDE-SEMICONDUCTOR optoelectronic integrated circuit
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A Novel Digital Transceiver for CT0 Standard 被引量:1
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作者 陈殿玉 许长喜 +7 位作者 陈浩琼 李振 郭秀丽 惠志强 施鹏 王跃 吴岳 熊绍珍 《Journal of Semiconductors》 EI CAS CSCD 北大核心 2007年第6期833-841,共9页
This paper introduces a novel digital transceiver for the cordless telephone zero (CT0) standard,which uses a digital modulation and demodulation technique to handle the signal instead of the traditional analog meth... This paper introduces a novel digital transceiver for the cordless telephone zero (CT0) standard,which uses a digital modulation and demodulation technique to handle the signal instead of the traditional analog meth-od. In the transmitter,a fractional-N phase locked loop (PLL) is utilized to realize the continuous phase frequency shift key (CPFSK) modulation,and a 2 Ts raised cosine (2RC) shaping technique is used to reduce the occupied bandwidth. In the receiver,a novel digital method is proposed to demodulate the 2RC CPFSK signal. This chip is fabricated using an SMIC 0.35μm mixed signal CMOS process with a die size of 2mm × 2mm. With an external low noise amplifier (LNA),the sensitivity of the chip is better than -103dBm. 展开更多
关键词 RF transceiver fractional-N PLL CPFSK MODULATOR DEMODULATOR
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10Gb/s EML Module Based on Identical Epitaxial Layer Scheme 被引量:1
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作者 孙长征 熊兵 +7 位作者 王健 蔡鹏飞 田建柏 罗毅 刘宇 谢亮 张家宝 祝宁华 《Journal of Semiconductors》 EI CAS CSCD 北大核心 2005年第4期662-666,共5页
A 10Gb/s transmitter module containing an electroabsorption modulator monolithically integrated with a distributed feedback (DFB) semiconductor laser is fabricated using the identical epitaxial layer scheme.Gain-coupl... A 10Gb/s transmitter module containing an electroabsorption modulator monolithically integrated with a distributed feedback (DFB) semiconductor laser is fabricated using the identical epitaxial layer scheme.Gain-coupling mechanism is employed to improve the single mode yield of the DFB laser,while inductively coupled plasma dry etching technique is utilized to reduce the modulator capacitance.The integrated device exhibits a threshold current as low as 12mA and an extinction ratio over 15dB at -2V bias.The small signal modulation bandwidth is measured to be over 10GHz.The transmission experiment at 10Gb/s indicates a power penalty less than 1dB at a bit-error-rate of 10 -12 after transmission through 35km single mode fiber. 展开更多
关键词 DFB lasers EA modulators photonic integrated circuit gain-coupling
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Synthesis Scheme for Low Power Designs Under Timing Constraints 被引量:5
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作者 王玲 温东新 +1 位作者 杨孝宗 蒋颖涛 《Journal of Semiconductors》 EI CAS CSCD 北大核心 2005年第2期287-293,共7页
To minimize the power consumption with resources operating at multiple voltages a time-constrained algorithm is presented.The input to the scheme is an unscheduled data flow graph (DFG),and timing or resource constrai... To minimize the power consumption with resources operating at multiple voltages a time-constrained algorithm is presented.The input to the scheme is an unscheduled data flow graph (DFG),and timing or resource constraints.Partitioning is considered with scheduling in the proposed algorithm as multiple voltage design can lead to an increase in interconnection complexity at layout level.That is,in the proposed algorithm power consumption is first reduced by the scheduling step,and then the partitioning step takes over to decrease the interconnection complexity.The time-constrained algorithm has time complexity of O(n 2),where n is the number of nodes in the DFG.Experiments with a number of DSP benchmarks show that the proposed algorithm achieves the power reduction under timing constraints by an average of 46 5%. 展开更多
关键词 low power multiple supply voltages partitioning timing constraints SCHEDULING
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Three-stage Transformation of Chlorophyll Transient Fluorescence Pattern Under Sustained Dehydration and the Discovery of Critical Water Content in Seaweeds 被引量:2
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作者 武宝玕 陈贻竹 +1 位作者 臧汝波 曾呈奎 《Acta Botanica Sinica》 CSCD 2001年第11期1134-1139,共6页
The chlorophyll fluorescence kinetics of marine red alga Grateloupia turutunt Yamada, green alga Ulva pertusa Kjellm and brown alga Laminaria japonica Aresch during natural sustained dehydration were monitored and inv... The chlorophyll fluorescence kinetics of marine red alga Grateloupia turutunt Yamada, green alga Ulva pertusa Kjellm and brown alga Laminaria japonica Aresch during natural sustained dehydration were monitored and investigated. The pulse amplified modulation (PAM) system was used to analyze the distinct fluorescence parameters during thallus dehydration. Results proved that the fluorescence kinetics of different seaweed all showed three patterns of transformation with sustained water loss. These were: 1) peak kinetic pattern (at the early stage of dehydration fluorescence enhanced and quenched subsequently, representing a normal physiological state). 2) plateau kinetic pattern (with sustained water loss fluorescence enhanced continuously but quenching became slower, finally reaching its maximum). 3) Platform kinetic pattern (fluorescence fell and the shape of kinetic curve was similar to plateau kinetic pattern). A critical water content (CWC) could be found and defined as the percentage of water content just prior to the fluorescence drop and to be a significant physiological index for evaluation of plant drought tolerance. Once thallus water content became lower than this value the normal peak pattern can not be recovered even through rehydration, indicating an irreversible damage to the thylakoid membrane. The CWC value corresponding to different marine species were varied and negatively correlated with their desiccation tolerance, for example. Laminaria japonica had the highest CWC value (around 90%) and the lowest dehydration tolerance of the three. In addition, a fluorescence 'burst' was found only in red algae during rehydration. The different fluorescence parameters F-o, F-v and F-v, F-m were measured and compared during water loss. Both F-o and F-v increased in the first stage of dehydration but F-v/F-m. kept almost constant. So the immediate response of in vivo chlorophyll fluorescence to dehydration was an enhancement. Later with sustained dehydration F-o increased continuously while F-v decreased and tended to become smaller and smaller. The major changes in fluorescence (including fluorescence drop during dehydration and the burst during rehydration) were all attributed to the change in F-o instead of F-v This significance of F-o indicates that it is necessary to do more research on F-o as well as on its relationship with the state of thylakoid membrane. 展开更多
关键词 marine algae chlorophyll fluorescence DEHYDRATION REHYDRATION pulse amplified modulation fluorescence system
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DIGITAL PWM OF AC-AC MATRIX CONVERTER BASED ON OUTPUT-VOLTAGE ERROR FUNCTION 被引量:1
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作者 葛红娟 穆新华 +1 位作者 张绍 周波 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI 2005年第4期307-311,共5页
Based on the output-voltage error function, a novel time discrete modulation technique is proposed for matrix converters (MCs) and time-discrete difference equations of a MC circuit are derived. Switch states of MC ... Based on the output-voltage error function, a novel time discrete modulation technique is proposed for matrix converters (MCs) and time-discrete difference equations of a MC circuit are derived. Switch states of MC are obtained when the output voltage error function is minimized, thus the optimum combination of switch states is derived for the closed-loop control of MC. Meanwhile, advantages of the least calculation workload, the simple process, and the convenient for implementation are brought while switch states are described as space vectors in the α-β coordination system. Simulation and experimental results demonstrate the validity of the time-discrete modulation technique and the feasibility of the control approach. 展开更多
关键词 matrix converter time-discrete modulation error function switch state
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Ridge Waveguide Electro-Optic Polymer Modulator with a New Kind of Corona Poled Crosslinkable Polyurethane 被引量:1
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作者 杨晓红 杜云 +2 位作者 殷爱民 石志文 吴荣汉 《Journal of Semiconductors》 EI CAS CSCD 北大核心 2001年第2期130-133,共4页
A polymer electro optic modulator has been fabricated with the functional layer acting as a kind of corona poled crosslinkable polyurethane. The three optical layers, namely waveguide, photolithography and oxygen are... A polymer electro optic modulator has been fabricated with the functional layer acting as a kind of corona poled crosslinkable polyurethane. The three optical layers, namely waveguide, photolithography and oxygen are fabricated by spin coating. With the Reactive Ion Etching method, the ridge of the waveguide is constructed. With light at 1 31μm being fiber coupled to waveguide, the mode and the modulation properties of these devices are demonstrated in a micron control system. 展开更多
关键词 MODULATOR polymer ridge waveguide
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