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直流换相失败及恢复过程暂态无功特性及控制参数影响 被引量:89
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作者 屠竞哲 张健 +3 位作者 曾兵 刘明松 易俊 卜广全 《高电压技术》 EI CAS CSCD 北大核心 2017年第7期2131-2139,共9页
直流换相失败过程中与送受端系统交换的无功功率大幅变化,表现为对系统不利的"无功冲击负荷"特性,亟需对直流换相失败过程中的送受端暂态无功特性开展深入研究。为此,首先给出了直流稳态运行和暂态过程中的送受端无功方程,然... 直流换相失败过程中与送受端系统交换的无功功率大幅变化,表现为对系统不利的"无功冲击负荷"特性,亟需对直流换相失败过程中的送受端暂态无功特性开展深入研究。为此,首先给出了直流稳态运行和暂态过程中的送受端无功方程,然后分别分析了换相失败期间和恢复过程中直流送端和受端的暂态无功特性,最后在此基础上研究了直流控制系统参数对暂态无功特性的影响,并通过直流等值系统算例进行了验证。研究结果表明,换相失败期间,直流从受端系统吸收一定的无功功率,同时对送端系统先吸收大量的无功功率、再发出大量的无功功率;换相失败恢复过程中,直流对受端系统通常先发出大量的无功功率、再吸收一定的无功功率,同时从送端系统吸收一定的无功功率。通过优化直流低压限流环节、换相失败预测、电流控制器等重要控制参数,可以减小换相失败过程中直流与送受端系统交换的最大无功功率。 展开更多
关键词 失败及恢复过程 送受端系统 暂态无功特性 电压失稳 过电压 控制系统参数
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单极化雷达的空域零相移干扰抑制极化滤波器 被引量:4
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作者 戴幻尧 李永祯 +2 位作者 刘勇 常宇亮 王雪松 《系统工程与电子技术》 EI CSCD 北大核心 2011年第2期290-295,共6页
单极化雷达不具备极化信息获取和处理能力,这对极化域抗干扰造成了根本性的困难。利用天线在空域扫描时对来波的空域极化调制效应,研究了单极化雷达回波信号的极化分解与极化参数等估计方法。在此基础上,讨论了一种空域零相移干扰抑制... 单极化雷达不具备极化信息获取和处理能力,这对极化域抗干扰造成了根本性的困难。利用天线在空域扫描时对来波的空域极化调制效应,研究了单极化雷达回波信号的极化分解与极化参数等估计方法。在此基础上,讨论了一种空域零相移干扰抑制极化滤波器的设计方法。该法不仅能够有效抑制干扰,而且不会造成目标信号的幅度和相位失真,实现了雷达相参处理和极化信息处理的兼容工作。仿真和实测数据验证了方法的有效性和可行性。 展开更多
关键词 单极化 空域极化 干扰抑制极化滤波器 恢复
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计及相间电容影响的单相弧光接地过电压抑制策略研究 被引量:8
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作者 陈旭 刘美岑 《电力电容器与无功补偿》 北大核心 2020年第3期119-125,共7页
本文提出相间电容降低单相弧光接地过电压幅值及抑制电弧重燃的理论依据及相关措施。首先推导得出单相弧光接地非故障相过电压幅值、故障相恢复电压幅值以及故障相恢复电压平均速率与系统参数的理论联系。结合本文提出的理论探究相间电... 本文提出相间电容降低单相弧光接地过电压幅值及抑制电弧重燃的理论依据及相关措施。首先推导得出单相弧光接地非故障相过电压幅值、故障相恢复电压幅值以及故障相恢复电压平均速率与系统参数的理论联系。结合本文提出的理论探究相间电容对降低弧光接地过电压幅值以及抑制电弧重燃的重要作用。利用Matlab软件建立改进Mayr动态电弧仿真模型对结论进行仿真,验证文中结论的正确性与可靠性。最后,通过实例分析配电网加装并联电容器能够在不增加额外电容器配置的前提下同时解决无功补偿和弧光接地过电压问题,对配电网安全及经济运行具有指导性的意义。 展开更多
关键词 弧光接地 过电压 间电容 故障恢复电压 无功补偿 电弧仿真
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基于阀电流实时计算的故障录波分析方法
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作者 郑艺欣 李晓华 李昊 《电气自动化》 2024年第4期106-108,共3页
针对当前缺乏通过录波数据实时分析换流阀运行状况的问题,提出了一种基于阀电流实时计算的故障录波分析方法。首先,分析了录波数据中的触发脉冲编码方法,并根据触发脉冲编码和换流阀外部交直流电流实时计算阀状态;其次,提出了利用故障... 针对当前缺乏通过录波数据实时分析换流阀运行状况的问题,提出了一种基于阀电流实时计算的故障录波分析方法。首先,分析了录波数据中的触发脉冲编码方法,并根据触发脉冲编码和换流阀外部交直流电流实时计算阀状态;其次,提出了利用故障录波实时计算得到的阀状态检测换相失败及其恢复的方法;最后,基于某实际直流工程录波数据得到的阀状态实时计算结果和换相失败检测结果,验证了所提方法的有效性。计算结果表明,所提方法可为直流系统的故障诊断和今后控制保护的优化提供基础。 展开更多
关键词 高压直流输电 故障录波 故障分析 失败 恢复
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2.488 Gbit/s clock and data recovery circuit in 0.35 μm CMOS 被引量:1
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作者 王欢 王志功 +2 位作者 冯军 熊明珍 章丽 《Journal of Southeast University(English Edition)》 EI CAS 2006年第2期143-147,共5页
The design of a 2. 488 Gbit/s clock and data recovery (CDR) If for synchronous digital hierarchy (SDH) STM-16 receiver is described. Based on the injected phase-locked loop (IPLL) and D-flip flop architectures, ... The design of a 2. 488 Gbit/s clock and data recovery (CDR) If for synchronous digital hierarchy (SDH) STM-16 receiver is described. Based on the injected phase-locked loop (IPLL) and D-flip flop architectures, the CDR IC was implemented in a standard 0. 35 μan complementary metal-oxide-semiconductor (CMOS) technology. With 2^31 -1 pseudorandom bit sequences (PRBS) input, the sensitivity of data recovery circuit is less than 20 mV with 10^-12 bit error rate (BER). The recovered clock shows a root mean square (rms) jitter of 2. 8 ps and a phase noise of - 110 dBc/Hz at 100 kHz offset. The capture range of the circuit is larger than 40 MHz. With a 5 V supply, the circuit consumes 680 mW and the chip area is 1.49 mm × 1 mm. 展开更多
关键词 clock recovery data recovery phase-locked loop (PLL) PREPROCESSOR
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2.5Gb/s 0.18μm CMOS Clock and Data Recovery Circuit 被引量:2
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作者 刘永旺 王志功 李伟 《Journal of Semiconductors》 EI CAS CSCD 北大核心 2007年第4期537-541,共5页
A 2.5Gb/s clock and data recovery (CDR) circuit is designed and realized in TSMC's standard 0.18/μm CMOS process. The clock recovery is based on a PLL. For phase noise optimization,a dynamic phase and frequency de... A 2.5Gb/s clock and data recovery (CDR) circuit is designed and realized in TSMC's standard 0.18/μm CMOS process. The clock recovery is based on a PLL. For phase noise optimization,a dynamic phase and frequency detector (PFD) is used in the PLL. The rms jitter of the recovered 2.5GHz clock is 2.4ps and the SSB phase noise is - 111dBc/Hz at 10kHz offset. The rms jitter of the recovered 2.5Gb/s data is 3.3ps. The power consumption is 120mW. 展开更多
关键词 clock recovery data recovery phase locked loop dynamic phase and frequency detector
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西京医院成功实施世界首例机器人活体小肠移植手术 被引量:1
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《医学争鸣》 CAS 北大核心 2016年第1期7-7,共1页
2015年8月30日,来自陕西省洛南县的父亲杨某与多年患病的儿子同时被推进第四军医大学西京医院手术室。经过10个多小时的手术,在10个科室60多名医护人员的共同努力下,专家们采用机器人成功地切取了父亲180 cm的小肠,移植到了儿子的身上... 2015年8月30日,来自陕西省洛南县的父亲杨某与多年患病的儿子同时被推进第四军医大学西京医院手术室。经过10个多小时的手术,在10个科室60多名医护人员的共同努力下,专家们采用机器人成功地切取了父亲180 cm的小肠,移植到了儿子的身上。截至2015年9月16日,父亲已于术后第4天康复出院,儿子移植肠存活良好,恢复进食。 展开更多
关键词 小肠移植 西京医院 肠切除 免疫抑制药物 器官移植 淋巴组织 排斥反应 恢复相
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A New Type of Power Clock for DSCRL Adiabatic Circuit
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作者 罗家俊 李晓民 +1 位作者 陈潮枢 仇玉林 《Journal of Semiconductors》 EI CAS CSCD 北大核心 2002年第7期757-761,共5页
An asymmetry power clock,4 phase power clock supplying the power to the DSCRL(dual swing charge recovery logic) adiabatic circuit is presented.It is much simpler than the 6 phase power clock,symmetry power clock,us... An asymmetry power clock,4 phase power clock supplying the power to the DSCRL(dual swing charge recovery logic) adiabatic circuit is presented.It is much simpler than the 6 phase power clock,symmetry power clock,used in the DSCRL adiabatic circuit.Although the 4 phase power clock is simpler,the DSCRL adiabatic circuit still shows good performance and high efficiency of energy transfer and recovery.This conclusion has been proved by the result of the HSPICE simulation using the 0 6μm CMOS technology. 展开更多
关键词 DSCRL adiabatic circuit low power 4 phase power clock energy recover
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A 5-Gbit/s monolithically-integrated low-power clock recovery circuit in 0.18-μm CMOS
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作者 张长春 王志功 +3 位作者 施思 潘海仙 郭宇峰 黄继伟 《Journal of Southeast University(English Edition)》 EI CAS 2011年第2期136-139,共4页
In order to make a 10 Gbit/s 2:1 half-rate multiplexer operate without external clocks, a 5 Gbit/s clock recovery (CR) circuit is needed to extract the desired clock from one input data. For the CR circuit, a 3-sta... In order to make a 10 Gbit/s 2:1 half-rate multiplexer operate without external clocks, a 5 Gbit/s clock recovery (CR) circuit is needed to extract the desired clock from one input data. For the CR circuit, a 3-stage ring voltage-controlled oscillator (VCO) is employed to avoid an unreliable startup of a 2-stage VCO and a low oscillation frequency of a 4-stage VCO. A phase frequency detector (PFD) is used to expand the pull-in range to meet the wide tuning range of a VCO required by process-voltage-temperature (PVT) variation. SMIC 0. 18-μm CMOS technology is adopted and the core area is 170 μm ×270 μm. Measurements show that, under a 1.8 V supply voltage, it consumes only about 90 mW, and has an input sensitivity of less than 25 mV, an output single-ended swing of above 300 mV, a phase noise of - 114 dBc/Hz at 1 MHz offset and a pull-in range of 1 GHz. 展开更多
关键词 clock recovery phase frequency detector voltagecontrolled oscillator phase noise
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2.5Gb/s/ch 0.18μm CMOS Data Recovery Circuit
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作者 刘永旺 王志功 李伟 《Journal of Semiconductors》 EI CAS CSCD 北大核心 2007年第5期692-695,共4页
A 2.5Gb/s/ch data recovery (DR) circuit is designed for an SFI-5 interface. To make the parallel data bit-synchronization and reduce the bit error rate (BER) ,a delay locked loop (DLL) is used to place the cente... A 2.5Gb/s/ch data recovery (DR) circuit is designed for an SFI-5 interface. To make the parallel data bit-synchronization and reduce the bit error rate (BER) ,a delay locked loop (DLL) is used to place the center of the data eye exactly at the rising edge of the data-sampling clock. A single channel DR circuit was fabricated in TSMC's standard 0. 18μm CMOS process. The chip area is 0. 46mm^2. With a 2^32 - 1 pseudorandom bit sequence (PRBS) input,the RMS jitter of the recovered 2.5Gb/s data is 3.3ps. The sensitivity of the single channel DR is less than 20mV with 10-12 BER. 展开更多
关键词 data recovery delay locked loop bit-synchronization
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智商太低的孟尝君
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《语文世界(上旬刊)》 1996年第7期25-25,共1页
智商太低的孟尝君彭荆风战国时期的孟尝君田文,素以善于养士而著名;他广纳宾客企图称雄于乱世。但事与愿违,门下虽有三千客,却多是些酒囊饭袋,既不能帮助他西抑强秦,也不能使他安于故国,几次被齐王罢相,还不得不亡命于魏……这... 智商太低的孟尝君彭荆风战国时期的孟尝君田文,素以善于养士而著名;他广纳宾客企图称雄于乱世。但事与愿违,门下虽有三千客,却多是些酒囊饭袋,既不能帮助他西抑强秦,也不能使他安于故国,几次被齐王罢相,还不得不亡命于魏……这是因为貌似贤者的孟尝君本身智商太低... 展开更多
关键词 孟尝君 智商 战国时期 孔子 司马迁 函谷关 亡命徒 随行人员 鸟兽散 恢复相
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中国盐碱化草地改良利用取得重大突破
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《农业知识》 2004年第4期10-10,共1页
为攻克盐碱化难题,黑龙江省科学院自然资源研究所创新性地采用国际领先水平的人工促进和生态恢复相结合技术,改良利用盐碱化草地取得重大突破,碱斑减幅可达70%。据科研人员介绍,此举为盐碱化草地资源的深度开发利用、大力发展养殖业提... 为攻克盐碱化难题,黑龙江省科学院自然资源研究所创新性地采用国际领先水平的人工促进和生态恢复相结合技术,改良利用盐碱化草地取得重大突破,碱斑减幅可达70%。据科研人员介绍,此举为盐碱化草地资源的深度开发利用、大力发展养殖业提供了创新性的范例。 展开更多
关键词 草地改良 草地资源 自然资源研究 黑龙江省科学院 结合技术 碱斑 恢复相 深度开发利用 人工促进 科研人员
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Monolithical Integrated CMOS Injected Synchronized Ring
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作者 刘丽 王志功 +2 位作者 林其松 熊明珍 章丽 《Journal of Semiconductors》 EI CAS CSCD 北大核心 2004年第7期762-765,共4页
Oscillator IC technique is developed by combining injecting synchronization technique with a ring VCO.Using the technique,a novel 2 488GHz of monolithical integrated injected synchronized ring VCO (ISRVCO) is realize... Oscillator IC technique is developed by combining injecting synchronization technique with a ring VCO.Using the technique,a novel 2 488GHz of monolithical integrated injected synchronized ring VCO (ISRVCO) is realized in a standard 0 25μm CMOS process.The ISRVCO is characterized by the following performances: -100dBc /Hz@1MHz at free running frequency,-91 7dBc/Hz@10kHz when injection is locked.With the 3 3V of power supply,the tuning range is 150MHz and the locking range is 100MHz with 50m V p p signal injection. 展开更多
关键词 VCO PLL CRC injection synchronization optical transmission systems
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Design of 622 Mb/s Clock-recovery Monolithic IC for Optical Communication System
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作者 ZHANGYaqi ZHAOJie 《Semiconductor Photonics and Technology》 CAS 1998年第3期159-165,173,共8页
A monolithic clock-recovery circuit used in 622 Mb/s optical communication system is designed,which is based on the phase-locked loop theory,and uses bipolar transistor model.It overcomes the shortcoming of clock reco... A monolithic clock-recovery circuit used in 622 Mb/s optical communication system is designed,which is based on the phase-locked loop theory,and uses bipolar transistor model.It overcomes the shortcoming of clock recovery method based on filter,and implements monolithic clock-recovery IC.The designed circuits include phase detector,voltage-controlled oscillator and loop filter.Among them,the voltage-control oscillator is a modified two-stage ring oscillator,which provides quadrature clock signals and presents wide voltage-controlled range and high voltage-controlling sensitivity. 展开更多
关键词 Clock-recovery Phase Detector Phase-locked Loop Voltage-controlled Oscillator
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Electrical Neutrality and Symmetry Restoring Phase Transitions at High Density in a Two-Flavor Nambu-Jona-Lasinio Model
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作者 WANG Xiao-Ming ZHOU Bang-Rong 《Communications in Theoretical Physics》 SCIE CAS CSCD 2007年第6期1081-1087,共7页
A general research on chiral symmetry restoring phase transitions at zero temperature and finite chemical potentials under electrical neutrality condition has been conducted in a Nambu-Jona-Lasinio model to describe t... A general research on chiral symmetry restoring phase transitions at zero temperature and finite chemical potentials under electrical neutrality condition has been conducted in a Nambu-Jona-Lasinio model to describe twoflavor normal quark matter. Depending on whether mo/A, the ratio of dynamical quark mass in vacuum and the 3D momentum cutoff in the loop integrals, is less or greater than 0.413, the phase transition will be of the second or first order. A complete phase diagram of u quark chemical potential versus mo is given. With the electrical neutrality constraint, the region where the second order phase transition happens will be wider than the one without electrical neutrality limitation. The results also show that, for the value ofmo/A from QCD phenomenology, the phase transition must be of the first order. 展开更多
关键词 normal quark matter electrical neutrality Nambu-Jona-Lasinio model high density chiral symmetry restoring first and second order phase transitions
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In-situ synchrotron X-ray diffraction investigation on deformation behavior of Nb/NiTi composite during pre-straining process 被引量:1
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作者 Shun GUO Hui-hui ZHANG +6 位作者 Min-kyung KWAK Wang DING Guang-lei LIU Wen MA Hai-xia LIU Qing-kun MENG Xin-qing ZHAO 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2022年第8期2609-2619,共11页
The mechanisms responsible for deformation behavior in Nb/NiTi composite during pre-straining were investigated systematically using in-situ synchrotron X-ray diffraction, transmission electron microscopy and tensile ... The mechanisms responsible for deformation behavior in Nb/NiTi composite during pre-straining were investigated systematically using in-situ synchrotron X-ray diffraction, transmission electron microscopy and tensile test. It is shown that upon loading, the composite experiences elastic elongation and slight plastic deformation of B19′,B2 and β-Nb phases, together with the forward stress-induced martensitic(SIM) transformation from B2 to B19′. Upon unloading, the deformation mechanisms of the composite mainly involve elastic recovery of B19′, B2 and β-Nb phases,compression deformation of β-Nb phase and incomplete B19′→B2 reverse SIM transformation. In the tensile loading-unloading procedure, besides the inherent elastic deformation and SIM transformation, the(001) compound twins in B19′ martensite can also be conducive to the elastic deformation occurring in B19′-phase of the composite.Therefore, this composite can exhibit a large recoverable strain after unloading owing to the elastic deformation, and the partially reversible and consecutive SIM transformation together with the(001) compound twins. 展开更多
关键词 Nb/NiTi composite near-linear deformation behavior large recoverable strain martensitic transformation
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High efficiency spreading spectrum modulation using double orthogonal complex sequences
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作者 Shi Xiaohong 《Engineering Sciences》 EI 2012年第5期71-75,共5页
This paper presents a novel scheme of high efficiency spreading spectrum modulation using double orthogonal complex sequences (DoCS). In this scheme, input data bit-stream is split into many groups with length M. Ea... This paper presents a novel scheme of high efficiency spreading spectrum modulation using double orthogonal complex sequences (DoCS). In this scheme, input data bit-stream is split into many groups with length M. Each group is then mapped into a word of width M and then utihzed to select one sequence from 2u-2 DoCS sequences each with length L. After that, the selected sequence is modulated on carrier in quadrature phase shift keying (QPSK) mode. In addition, a new method named forward phase correction (FPC) is put forward for carrier recovery. Theoretical analysis and bit-error-ratio(BER) experiment results indicate that the proposed scheme has better performance than the conventional direct sequence spread spectrum(DSSS) scheme both in bandwidth efficiency and processing gain of the receiver. 展开更多
关键词 modulation and demodulation high efficiency spreading spectrum modulation forward phase correction double orthogonal complex sequences
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Particle Density in Zero Temperature Symmetry Restoring Phase Transitions in Four-Fermion Interaction Models
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作者 ZHOUBang-Rong 《Communications in Theoretical Physics》 SCIE CAS CSCD 2004年第2期247-251,共5页
By means of critical behaviors of the dynamical fermion mass in four-fermion interaction models, we show by explicit calculations that when T = 0 the particle density will have a discontinuous jumping across the criti... By means of critical behaviors of the dynamical fermion mass in four-fermion interaction models, we show by explicit calculations that when T = 0 the particle density will have a discontinuous jumping across the critical chemical potential μ<SUB>c</SUB> in 2D and 3D Gross-Neveu (GN) model and these physically explain the first-order feature of the corresponding symmetry restoring phase transitions. For the second-order phase transitions in the 3D GN model when T → 0 and in 4D Nambu–Jona–Lasinio (NJL) model when T = 0, it is proven that the particle density itself will be continuous across μ<SUB>c</SUB> but its derivative over the chemical potential μ will have a discontinuous jumping. The results give a physical explanation of implications of the tricritical point in the 3D GN model. The discussions also show effectiveness of the critical analysis approach of phase transitions. 展开更多
关键词 Gross-Neveu and Nambu-Jona-Lasinio models symmetry restoration at zero temperature and high density particle number density first- and second-order phase transitions
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Characteristics of soil enzymes and the dominant species of repair trees in the reclamation of coal mine area 被引量:1
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作者 Wen-Ying ZHANG Duo-Xi YAO +3 位作者 Zhi-Guo ZHANG Qing YANG Kui ZHAO Shi-Kai AN 《Journal of Coal Science & Engineering(China)》 2013年第2期256-261,共6页
In order to study the soil enzyme content at the mine reclamation area and choose a tree species with superior restoration capabilities, this paper takes Huainan Datong Mine as the study area, and five different enzym... In order to study the soil enzyme content at the mine reclamation area and choose a tree species with superior restoration capabilities, this paper takes Huainan Datong Mine as the study area, and five different enzymes under nine tree species as the study subject. The different enzyme activity indexes were measured, and the correlation analysis and the principal component analysis (PCA) method were applied to evaluate and screen the tree species with advanced restoration. The results demonstrate that there are some correlations among the different soil enzymes, including some very significant positive correlations among urease, phosphatase, invertase and protease. The best species in terms of repair is privet, and the worst is Haltong. This study provides a scientific basis for the selection of restoration-capable tree species in the reclamation area of the coal mine. 展开更多
关键词 reclamation area coal mine soil enzyme correlation analysis principal component analysis
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Realization of 40 GHz Short Time Windows and Their Applications in High Speed Optical Time Division Multiplexing Systems 被引量:1
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作者 Li Yan Wu Jian 《China Communications》 SCIE CSCD 2012年第8期40-51,共12页
Optical Time Division Multiplexing (OTDM) is known to be capable of transmitting single channel high bit rate data stream with low speed electro-optical components. A cost-effective, compact and stable short time wi... Optical Time Division Multiplexing (OTDM) is known to be capable of transmitting single channel high bit rate data stream with low speed electro-optical components. A cost-effective, compact and stable short time window with low insert loss, low phase noise, low timing-jitter and high speed performance is essential for ultra-high speed OTDM systems using phase and amplitude modulation formats. In this paper, we review three promising methods to obtain 40 GHz short time window including Electro-Absorption Modulator (EAM), Dual-Parallel Mach-Zehnder Modulator (DPMZM) and Fiber Loop-Polarization Modulator (FL-PolM). Sub-picosecond short pulse source generation, optical time division denlaltiplexing and clock recovery are realized respectively by using the short time window based on the three methods. By using DPMZM based pulse source and EAM based Clock Recovery (CR) and dermltiplexer, error free transmission of 640 Goit/s (160 Gbaud/s Pol-Mux DQPSK) single channel signal over 400 km single mode fiber is proven to be experimentally successful. 展开更多
关键词 optical fiber conmmnication optical time division nmltiplexing optical tirre switch
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