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The effect of f(T) gravity on an interplanetary clock and its time transfer link 被引量:2
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作者 Xue-Mei Deng Yi Xie 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2013年第10期1225-1230,共6页
As an extension of the"teleparallel"equivalent of general relativity,f(T)gravity is proposed to explain some puzzling cosmological behaviors,such as accelerating expansion of the Universe.Given the fact that modif... As an extension of the"teleparallel"equivalent of general relativity,f(T)gravity is proposed to explain some puzzling cosmological behaviors,such as accelerating expansion of the Universe.Given the fact that modified gravity also has impacts on the Solar System,we might test it during future interplanetary missions with ultrastable clocks.In this work,we investigate the effects of f(T)gravity on the dynamics of the clock and its time transfer link.Under these influences,theΛ-term and theα-term of f(T)gravity play important roles.Here,Λis the cosmological constant andαrepresents a model parameter in f(T)gravity that determines the divergence from teleparallel gravity at the first order approximation.We find that the signal of f(T)gravity in the time transfer is much more difficult to detect with the current state of development for clocks than those effects on dynamics of an interplanetary spacecraft with a bounded orbit with parameters 0.5 au≤a≤5.5 au and 0≤e≤0.1. 展开更多
关键词 gravitation celestial mechanics space vehicles:clock time
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A Fast Averaging Synchronization Algorithm for Clock Oscillators in Nonlinear Dynamical Network with Arbitrary Time-delays 被引量:7
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作者 CHEN Jie 《自动化学报》 EI CSCD 北大核心 2010年第6期873-880,共8页
关键词 运算法则 FASA 振荡器 自动化
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Physics of Clocks in Absolute Space-Time 被引量:3
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作者 Edwin Eugene Klingman 《Journal of Modern Physics》 2020年第12期1950-1968,共19页
20th century physics experimentally established beyond doubt the fact that moving clocks read differently from “static” clocks. This fact is typically interpreted as support for special relativity. On the other hand... 20th century physics experimentally established beyond doubt the fact that moving clocks read differently from “static” clocks. This fact is typically interpreted as support for special relativity. On the other hand, the same century produced proof that clocks at various locations in the gravitational field also read differently, and this fact is explained by general relativity, which is, in general, not Lorentz transformable. This paper establishes a common framework for the physics of clocks in these different situations. 展开更多
关键词 RELATIVITY time Dilation Space-time Ontology clock Slowdown Inertial clocks Absolute Space and time Inertial Mass Covariance Principle Ideal clocks
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Using a Grandfather Pendulum Clock to Measure the World’s Shortest Time Interval, the Planck Time (With Zero Knowledge of <i>G</i>) 被引量:1
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作者 Espen Gaarder Haug 《Journal of Applied Mathematics and Physics》 2021年第5期1076-1088,共13页
Haug has recently introduced a new theory of unified quantum gravity coined “<em>Collision Space-Time</em>”. From this new and deeper understanding of mass, we can also understand how a grandfather pendu... Haug has recently introduced a new theory of unified quantum gravity coined “<em>Collision Space-Time</em>”. From this new and deeper understanding of mass, we can also understand how a grandfather pendulum clock can be used to measure the world’s shortest time interval, namely the Planck time, indirectly, without any knowledge of G. Therefore, such a clock can also be used to measure the diameter of an indivisible particle indirectly. Further, such a clock can easily measure the Schwarzschild radius of the gravity object and what we will call “Schwarzschild time”. These facts basically prove that the Newton gravitational constant is not needed to find the Planck length or the Planck time;it is also not needed to find the Schwarzschild radius. Unfortunately, there is significant inertia towards new ideas that could significantly alter our perspective on the fundamentals in the current physics establishment. However, this situation is not new in the history of science. Still, the idea that the Planck time can be measured totally independently of any knowledge of Newton’s gravitational constant could be very important for moving forward in physics. Interestingly, an old instrument that today is often thought of as primitive instrument can measure the world’s shortest possible time interval. No atomic clock or optical clock is even close to be able to do this. 展开更多
关键词 Pendulum clock Planck time Planck Length Planck Scale Planck Constant Schwarzschild Radius Schwarzschild time Collision time Newton’s Gravitational Constant Huygens
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A high precision time-to-digital converter based on multi-phase clock implemented within Field-Programmable-Gate-Array 被引量:7
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作者 CHEN Kai LIU Shubin AN Qi 《Nuclear Science and Techniques》 SCIE CAS CSCD 2010年第2期123-128,共6页
In this paper, the design of a coarse-fine interpolation Time-to-Digital Converter (TDC) is implemented in an ALTERA’s Cyclone FPGA. The carry-select chain performs as the tapped delay line. The Logic Array Block (LA... In this paper, the design of a coarse-fine interpolation Time-to-Digital Converter (TDC) is implemented in an ALTERA’s Cyclone FPGA. The carry-select chain performs as the tapped delay line. The Logic Array Block (LAB) having a propagation delay of 165 ps in the chain is synthesized as delay cell. Coarse counters triggered by the global clock count the more significant bits of the time data. This clock is also fed through the delay line, and LABs create the copies. The replicas are latched by the tested event signal, and the less significant bits are encoded from the latched binary bits. Single-shot resolution of the TDC can be 60 ps. The worst Differential Nonlinearity (DNL) is about 0.2 Least Significant Bit (LSB, 165 ps in this TDC module), and the Integral Nonlinearity (INL) is 0.6 LSB. In comparison with other architectures using the synchronous global clock to sample the taps, this architecture consumed less electric power and logic cells, and is more stable. 展开更多
关键词 现场可编程门阵列 时间数字转换器 位时钟 高精度 抽头延迟线 多相 基础 微分非线性
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Efficient Harmonic Analysis Technique for Prediction of IGS Real-Time Satellite Clock Corrections
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作者 Mohamed Elsayed Elsobeiey 《Positioning》 2017年第3期37-45,共9页
Real-time satellite orbit and clock corrections obtained from the broadcast ephemerides can be improved using IGS real-time service (RTS) products. Recent research showed that applying such corrections for broadcast e... Real-time satellite orbit and clock corrections obtained from the broadcast ephemerides can be improved using IGS real-time service (RTS) products. Recent research showed that applying such corrections for broadcast ephemerides can significantly improve the RMS of the estimated coordinates. However, unintentional streaming interruption may happen for many reasons such as software or hardware failure. Streaming interruption, if happened, will cause sudden degradation of the obtained solution if only the broadcast ephemerides are used. A better solution can be obtained in real-time if the predicted part of the ultra-rapid products is used. In this paper, Harmonic analysis technique is used to predict the IGS RTS corrections using historical broadcasted data. It is shown that using the predicted clock corrections improves the RMS of the estimated coordinates by about 72%, 58%, and 72% in latitude, longitude, and height directions, respectively and reduces the 2D and 3D errors by about 80% compared with the predicted part of the IGS ultra-rapid clock corrections. 展开更多
关键词 REAL-time Service clock PREDICTION PRECISE Point Positioning
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低功耗Clock-Gating技术在SAR实时成像处理中的应用
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作者 陈冰冰 邵洁 +1 位作者 王贞松 赵荣彩 《电子与信息学报》 EI CSCD 北大核心 2005年第3期449-453,共5页
功耗问题在SAR实时成像系统中是不容忽视的。该文以实时成像系统中的输入分机为研究平台,测试了信号处理中常用芯片DSP,SBSRM,FPGA在采用Clock-gating技术前后,功耗的变化。通过大量的实验结果,验证了Clock-gating技术在SAR实时信号处... 功耗问题在SAR实时成像系统中是不容忽视的。该文以实时成像系统中的输入分机为研究平台,测试了信号处理中常用芯片DSP,SBSRM,FPGA在采用Clock-gating技术前后,功耗的变化。通过大量的实验结果,验证了Clock-gating技术在SAR实时信号处理中的可行性,对降低SAR实时成像系统,尤其是星载实时成像系统的功耗有一定的指导意义。 展开更多
关键词 SAR实时成像处理 低功耗 clock-gating技术
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酸枣仁汤对慢性睡眠剥夺大鼠视交叉上核生物钟基因Clock和Bmal1表达的影响 被引量:14
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作者 张付民 冉仁国 赵宾宾 《湖南中医药大学学报》 CAS 2019年第1期19-22,共4页
目的观察酸枣仁汤对慢性睡眠剥夺大鼠视交叉上核(uprachiasmatic nucleus, SCN)生物钟基因Clock和Bmal1蛋白表达的影响。方法将实验大鼠随机分为空白组、模型组、舒乐安定组和酸枣仁汤组,除空白组外,其他各组用多平台水环境法制定慢性... 目的观察酸枣仁汤对慢性睡眠剥夺大鼠视交叉上核(uprachiasmatic nucleus, SCN)生物钟基因Clock和Bmal1蛋白表达的影响。方法将实验大鼠随机分为空白组、模型组、舒乐安定组和酸枣仁汤组,除空白组外,其他各组用多平台水环境法制定慢性睡眠剥夺模型并予以相应干预。采用自主活动测试仪记录大鼠自主活动时间,免疫组化和Western blot检测SCN中Clock和Bmal1蛋白表达水平。结果与空白组比较,模型组大鼠自主活动时间TL(光照时段4个点之和)、TD(黑暗时段4个点之和)、TALL(光照+黑暗8个时段之和)明显增加(P<0.01);SCN中Clock和Bmal1蛋白表达水平下降(P<0.01)。干预后,与模型组比较,舒乐安定组和酸枣仁汤组大鼠TL、TD、TALL均减少(P<0.01或P<0.05)。舒乐安定组和酸枣仁汤组大鼠SCN中Clock和Bmal1蛋白表达上升(P<0.01或P<0.05)。结论酸枣仁汤能改善慢性睡眠剥夺大鼠的睡眠状态,其机制可能与酸枣仁汤调节大鼠SCN中Clock和Bmal1的表达有关。 展开更多
关键词 视交叉上核 酸枣仁汤 睡眠剥夺 生物钟基因 clock BMAL1 自主活动时间
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The Importance of Time Synchronization in the Local Networks of the Science and Application Center for Lunar and Deep-space Exploration 被引量:1
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作者 LIUGuoping OUYANGZiyuan +1 位作者 LIChunlai LIUJianfeng 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2004年第5期1104-1108,共5页
The data acquisition stations and the data processing center of the Science and Application Center for Lunar and Deep-space Exploration (SACLuDE) are located at different geographical sites. They respectively have the... The data acquisition stations and the data processing center of the Science and Application Center for Lunar and Deep-space Exploration (SACLuDE) are located at different geographical sites. They respectively have their own local networks and interconnect with each other through access to the core data network. This paper describes the clock drift in the computer and other networked devices building up the infrastructure of the above local networks. The network time variance of the stochastic model is also estimated. The poor precision of network synchronization will bring about potential hazards to the network operation and application running in the networks, which is clarified in the present paper. At the end of the paper, a cost-effective and feasible solution is proposed based on the Global Position System (GPS) and the Network Time Protocol (NTP). 展开更多
关键词 SACLuDE clock drift network time variance network synchronization GPS NTP
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Modeling perisaccadic time perception 被引量:1
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作者 Andrea Guazzini Pietro Liò +1 位作者 Andrea Passarella Marco Conti 《Journal of Biomedical Science and Engineering》 2010年第12期1133-1142,共10页
There is an impressive scarcity of quantitative models of the clock patterns in the brain. We propose a mesoscopic approach, i.e. neither a description at single neuron level, nor at systemic level/too coarse granular... There is an impressive scarcity of quantitative models of the clock patterns in the brain. We propose a mesoscopic approach, i.e. neither a description at single neuron level, nor at systemic level/too coarse granularity, of the time perception at the time of the saccade. This model uses functional pathway knowledge and is inspired by, and integrates, recent findings in both psychophysics and neurophysiology. Perceived time delays in the perisaccadic window are shown numerically consistent with recent experimental measures. Our model provides explanation for several experimental outcomes on saccades, estimates popu-lation variance of the error in time perception and represent a meaningful example for bridging psychophysics and neurophysiology. Finally we found that the insights into information processing during saccadic events lead to considerations on engineering exploitation of the underlying phenomena. 展开更多
关键词 BRAIN clock SACCADES time Compression time PERCEPTION Craniotopiccoordinates
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Deriving of the Generalized Special Relativity (GSR) by Using Mirror Clock and Lorentz Transformations 被引量:1
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作者 M. H. M. Hilo R. Abd Elgani +2 位作者 R. Abd Elhai M. D. Abd Allah Amel A. A. Elfaki 《Natural Science》 2014年第17期1275-1281,共7页
Einstein relativity theory shows its high capability of promoting itself to solve the long stand physical problems. The so-called generalized special relativity (GSR) was derived later, using the beautiful Einstein re... Einstein relativity theory shows its high capability of promoting itself to solve the long stand physical problems. The so-called generalized special relativity (GSR) was derived later, using the beautiful Einstein relation between field and space-time curvature. In this work we re-derive (GSR) expression of time by incorporating the field effect in it, and by using mirror clock and Lorentz transformations. This expression reduces to that of (GSR) the previous conventional one, besides reducing to special relativistic expression. It also shows that the speed of light is constant inside the field and is equal to C. This means that the observed decrease of light in matter and field is attributed to the strong interaction of photons with particles and mediates which causes successive absorption and reemission processes that lead to time delay. This absorption process makes some particles appear to move faster than light within the field or medium. This new expression, unlike that of GSR, can describe time and coordinate relativistic expressions for strong as well as weak fields at constant acceleration. 展开更多
关键词 LORENTZ TRANSFORMATIONS MIRROR clock Space-time Curvature GRAVITATIONAL Field
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Review of satellite disciplined clock system
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作者 单庆晓 杨俊 《Journal of Measurement Science and Instrumentation》 CAS 2012年第1期51-56,共6页
Satellite disciplined clock system(SDCS)composed of satellite timing receiver and local frequency synthesis is widely applied for its high accuracy and low cost.This paper provides a review of SDCS.Key technologies su... Satellite disciplined clock system(SDCS)composed of satellite timing receiver and local frequency synthesis is widely applied for its high accuracy and low cost.This paper provides a review of SDCS.Key technologies such as phase difference measurement,pulse noise process and frequency calibration are surveyed in detail.Disciplined clock model based on PI controller is built and disciplined process is analyzed.The methods of realizing the disciplined clock circuit are classified and summarized.A prototype based on FPGA is proposed.At last development trend of SDCS is discussed. 展开更多
关键词 GPS(global positioning system) Beidou system satellite disciplined clock TIMING frequency calibration
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Effects of feeding time on complement component C7 expression in Pelteobagrus vachellii subject to bacterial challenge
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作者 SHAO Ting QIN Chuanjie +4 位作者 DUAN Huiguo YUAN Dengyue WEN Zhengyong WANG Jun GE Fanglan 《Journal of Oceanology and Limnology》 SCIE CAS CSCD 2018年第6期2358-2367,共10页
Shifting the feeding time for fish from daytime to nighttime could alter their digestive behavior, disturb their metabolism, and may af fect immune-related genes. This study aimed to clone complement component C7 and ... Shifting the feeding time for fish from daytime to nighttime could alter their digestive behavior, disturb their metabolism, and may af fect immune-related genes. This study aimed to clone complement component C7 and analyze the different expression of C7 mRNA in fish fed during either the day or at night and then challenged with Aeromonas hydrophila infection. The P v-C7 cDNA of Pelteobagrus vachellii contained 2 647 bp with an open reading frame encoding a protein of 818 amino acids. Multiple sequences analysis indicated that P v-C7 included eight domains, which was similar to results for other species. Quantitative PCR analysis showed that P v-C7 was mainly expressed in the liver, spleen, intestine and head kidney tissues of healthy P. vachellii. Quantitative PCR analysis showed that C7 mRNA transcript in the liver, spleen and head kidney also increased significantly when the fish were fed at nighttime(20:00). In addition, the expression of Pv-C7 mRNA significantly increased with A. hydrophila challenge in the liver(48–96 h), spleen and head kidney(12–96 h) tissues of P. vachellii. Pv-C7 mRNA expression of the fish fed at nighttime showed significant higher than that in the fish fed at day time at 12–48 h in head kidney and 12–24 h in spleen. This study indicates that altering the feeding time from daytime to nighttime could increase P v-C7 mRNA expression, and feeding time may af fect the immune response involving C7. 展开更多
关键词 Pelteobagrus vachellii COMPLEMENT COMPONENT C7 SHIFTING FEEDING time clock
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A High-Precision Time Handling Library 被引量:1
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作者 Irina Fedotova Eduard Siemens Hao Hu 《通讯和计算机(中英文版)》 2013年第8期1076-1086,共11页
关键词 时间处理 高精度 网络性能 时间计数器 Linux 计算机资源 时间控制 测量程序
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Distributed Time Synchronization in Wireless Sensor Networks via Second-Order Consensus Algorithms 被引量:2
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作者 吴杰 白煜 张立毅 《Transactions of Tianjin University》 EI CAS 2015年第2期113-121,共9页
This paper proposes a distributed second-order consensus time synchronization, which incorporates the second-order consensus algorithm into wireless sensor networks. Since local clocks may have different skews and off... This paper proposes a distributed second-order consensus time synchronization, which incorporates the second-order consensus algorithm into wireless sensor networks. Since local clocks may have different skews and offsets, the algorithm is designed to include offset compensation and skew compensation. The local clocks are not directly modified, thus the virtual clocks are built according to the local clocks via the compensation parameters. Each node achieves a virtual consensus clock by periodically updated compensation parameters. Finally, the effectiveness of the proposed algorithm is verified through a number of simulations in a mesh network. It is proved that the proposed algorithm has the advantage of being distributed, asymptotic convergence, and robust to new node joining. 展开更多
关键词 wireless sensor network time SYNCHRONIZATION SECOND-ORDER CONSENSUS clock SKEW clock OFFSET
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On the Trade-off between Power Consumption and Time Synchronization Quality for Moving Targets under Large-Scale Fading Effects in Wireless Sensor Networks
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作者 Pablo Briff Leonardo Rey Vega +1 位作者 Ariel Lutenberg Fabian Vargas 《Communications and Network》 2013年第3期498-503,共6页
In this work we find a lower bound on the energy required for synchronizing moving sensor nodes in a Wireless Sensor Network (WSN) affected by large-scale fading, based on clock estimation techniques. The energy requi... In this work we find a lower bound on the energy required for synchronizing moving sensor nodes in a Wireless Sensor Network (WSN) affected by large-scale fading, based on clock estimation techniques. The energy required for synchronizing a WSN within a desired estimation error level is specified by both the transmit power and the required number of messages. In this paper we extend our previous work introducing nodes’ movement and the average message delay in the total energy, including a comprehensive analysis on how the distance between nodes impacts on the energy and synchronization quality trade-off under large-scale fading effects. 展开更多
关键词 WIRELESS Sensor Networks clock OFFSET Estimation time SYNCHRONIZATION WIRELESS Channel FADING Moving TARGETS
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一种应用于TDMA无线传感网的低能耗同步机制 被引量:2
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作者 刘高平 徐锋 《浙江万里学院学报》 2024年第1期87-95,共9页
为了降低时分多址网络中时钟同步所导致的节点能耗,根据节点晶振器件的潜在漂移,提出了一种应用于星型无线传感网的低能耗同步机制。该机制中整个时间轴由长帧组成,每个长帧包含一个同步帧与多个子帧,每个子帧由所有子节点绑定的子时隙... 为了降低时分多址网络中时钟同步所导致的节点能耗,根据节点晶振器件的潜在漂移,提出了一种应用于星型无线传感网的低能耗同步机制。该机制中整个时间轴由长帧组成,每个长帧包含一个同步帧与多个子帧,每个子帧由所有子节点绑定的子时隙构成。根节点在长帧开始时发送同步帧,使得所有子节点时钟同步。每个子时隙增加了相应的保护间隔,有效地避免子节点之间因时钟漂移导致时隙间相互影响,从而最大限度地增加长帧中的子帧数量,降低子节点唤醒进行同步的频率。与传统的TDMA每个子帧均需同步相比,从接收同步帧角度来讲,大幅度减少了子节点能耗。最后,假定晶振频率误差为正态分布的情况下,利用MATLAB进行仿真,验证了该低能耗同步模型公式的正确性,并将仿真情况在CC1310器件构建的星型网上进行了应用验证。 展开更多
关键词 时钟同步 时隙 保护间隔 时钟漂移 低能耗
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On Energy-Efficient Time Synchronization for Wireless Sensors under Large-Scale and Small-Scale Fading Effects
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作者 Pablo Briff Ariel Lutenberg +1 位作者 Leonardo Rey Vega Fabian Vargas 《Wireless Sensor Network》 2013年第10期181-193,共13页
In this work, the existing trade-off between time synchronization quality and energy is studied for both large-scale and small-scale fading wireless channels. We analyze the clock offset estimation problem using one-w... In this work, the existing trade-off between time synchronization quality and energy is studied for both large-scale and small-scale fading wireless channels. We analyze the clock offset estimation problem using one-way, two-way and N-way message exchange mechanisms affected by Gaussian and exponentially distributed impairments. Our main contribution is a general relationship between the total energy required for synchronizing a wireless sensor network and the clock offset estimation error by means of the transmit power, number of transmitted messages and average message delay, deriving the energy optimal lower bound as a function of the time synchronization quality and the number of hops in a multi-hop network. 展开更多
关键词 WIRELESS Sensor Networks clock OFFSET Estimation time Synchronization WIRELESS Channel FADING
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A Versatile Industrial Timer and Real Time Keeper
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作者 Sagar. G Yadav K. A Narayanankutty 《Wireless Engineering and Technology》 2011年第3期196-203,共8页
Industrial timer requirements are multifaceted. On-delay, off-delay, cyclic or sequential timing requirements, with usual time range varying from seconds to days, depending on the process. Custom build timers cannot p... Industrial timer requirements are multifaceted. On-delay, off-delay, cyclic or sequential timing requirements, with usual time range varying from seconds to days, depending on the process. Custom build timers cannot provide all of these requirements simultaneously and hence an advanced timer rectifying this shortcoming has been designed and fabricated in this work. This timer is based on the real time clock chip used in mother boards. Our design can be programmed for a specific time requirement and can later be put to work in standalone mode. A demonstration board is fabricated and tested. 展开更多
关键词 INDUSTRIAL timeR Real time clock Programmable Standalone DS1307 I2C USART ZigBee Bluetooth
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Improvements and New Evaluation of NIM4 Cesium Fountain Clock and Construction of NIM5 Clock in 2006 被引量:1
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作者 Li Tianchu, Li Mingshou, Lin Pingwei, Wang Ping, Chen Weiliang, Liu Nianfen, Lin Yige(National Institute of Metrology (NIM), No.18,Beisanhuandong Rd, Beijing 100013, China) 《工程科学(英文版)》 2007年第2期124-128,共5页
The NIM4 cesium fountain clock has been operating stably and sub-continually since Aug. 2003. In this paper we present improvements on NIM4 in 2005-2006 and the most recent evaluation for its frequency shifts with an ... The NIM4 cesium fountain clock has been operating stably and sub-continually since Aug. 2003. In this paper we present improvements on NIM4 in 2005-2006 and the most recent evaluation for its frequency shifts with an uncertainty of 5E-15. A 220 days comparison between NIM4 and GPS showed an agreement of 2E-14. Finally the construction of a NIM5 transportable cesium fountain clock is briefly reported. 展开更多
关键词 METROLOGY time and frequency standards CESIUM FOUNTAIN clock
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