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61.
龚向东 《南昌大学学报(理科版)》1992,16(3):1
本文介绍一种用MCS—51汇编语言设计的单片微机系统时钟软件。该软件所需的中断服务时间短,因而不影响CPU进行其他实时性较高的处理工作,该软件还能提供时间显示功能,文中给出了相应的显示硬件结构。 相似文献
62.
B. Bureau G. Silly J. Y. Buzar C. Legein D. Massiot 《Solid state nuclear magnetic resonance》1999,14(3-4):181-190
Owing to the implementation of acquisition techniques specific for nuclei with very large quadrupolar interaction (full shifted echo and variable offset cumulative spectra (VOCS)), NMR spectra of 69Ga and 71Ga are obtained in crystallised (PbGaF5, Pb3Ga2F12, Pb9Ga2F24 and CsZnGaF6) and glassy (PbF2–ZnF2–GaF3) gallium fluorides. Simulations of both static (full echo or VOCS) and 15 kHz MAS spectra allow to obtain consistent determinations of isotropic chemical shifts and very large quadrupolar parameters (νQ up to 14 MHz). In the crystalline compounds whose structures are unknown, the number and the local symmetry of the different gallium sites are tentatively worked out. For the glassy systems, a continuous Czjzek's distribution of the NMR quadrupolar parameters accounts for the particular shape of the NMR spectrum. 相似文献
63.
We discuss gravitomagnetism in connection with rotating cylindrical systems. In particular, the gravitomagnetic clock effect is investigated for the exterior vacuum field of an infinite rotating cylinder. The dependence of the clock effect on the parameters of the stationary Lewis metric is determined. We illustrate our results by means of the van Stockum spacetime. 相似文献
64.
In this paper, the effective pyroelectric coefficient
and polarization offset of
the compositionally step-like graded multilayer ferroelectric structures
have been studied by use of the first-principles approach.
It is exhibited that the dielectric gradient has a nontrivial influence
on the effective pyroelectric coefficient, but has a little influence
on the polarization offset; and the polarization gradient
plays an important role in the abnormal hysteresis loop phenomenon
of the compositionally step-like graded ferroelectric structures.
Moreover, the origin of the polarization offset is explored,
which can be attributed to the polarization gradient
in the compositionally step-like graded structure. 相似文献
65.
A protocol for multipartite quantum clock synchronization is performed under the influence of Unruh thermal noise. The dynamics of multipartite quantum system consisting of Unruh–DeWitt detectors when one of the detectors is accelerated are obtained. To estimate the time difference between the clocks, the time probability is calculated and how the probability is influenced by the Unruh thermal noise and other factors is analyzed. It is shown that both relativistic motion and interaction between the atom and the external scalar field affect the choice of optimal number of excited atoms in the initial state, which leads to a higher clock adjustment accuracy. Time probabilities for different types of initial states approach the same value in the limit of infinite acceleration, while tend to different minimums with increasing number of atoms. In addition, the accuracy of clock synchronization using a pair of entangled clocks in two‐party system is always higher than in a multipartite system, while the optimal Z‐type multipartite initial state always performs better than the W‐type state. 相似文献
66.
For more than four decades, the lowest excitation in the whole landscape of atomic nuclei, the low‐lying, isomeric state of 229Th, the so‐called thorium isomer, has challenged physicists of various disciplines. Being a solitaire with its uniquely low excitation energy of <10 eV, its predicted lifetime of a few hours results in an extremely sharp relative linewidth ΔE/E as low as 10–20. While until recently the indication of its existence was based only on indirect evidence, its unique properties inspired a multitude of potential applications, like the use of the thorium isomer as a nuclear frequency standard, potentially able to outperform even the best atomic clocks and a sensitivity‐enhanced access to potential temporal variations of fundamental constants. The various proposals to exploit the unique properties of 229mTh are presented herein, in particular focusing on its ability to serve as a test bench for time variations of fundamental constants like the fine structure constant. 相似文献
67.
68.
建立了同时测定紫外光固化(UV)胶印油墨中27种溶剂残留(挥发性有机化合物,VOCs)的顶空-气相色谱-质谱联用(HS-GC-MS)法。将UV胶印油墨样品模拟印刷制成一定面积、厚度的试样,在紫外灯下烘烤1 min,经80℃、45 min静态顶空后,通过VOC专用毛细管柱分离和质谱检测,外标法定量。27种VOCs均呈现良好的线性关系,相关系数(R2)均≥0.9950;方法的检出限(LODs,S/N=3)为0.001~0.310 mg/m2,定量限(LOQs,S/N=10)为0.003~0.920 mg/m2;样品的平均加标回收率为80%~108%,相对标准偏差(RSD)<6%(n=6)。该方法制样便捷,灵敏度高,精密度好,准确度高,将其应用于实际UV胶印油墨样品的检测,取得了良好效果。 相似文献
69.
提出了一种利用Fabry-Perot(FP)半导体激光器同步提取波长转换的分路光时钟的新方法,并对该方法进行了数值模拟和实验验证.光注入半导体激光器会产生非线性单周期振荡特性,利用交叉增益调制效应及对单周期振荡的微波锁频效应,可从光时分复用信号中提取出波长转换的分路光时钟.采用一个FP半导体激光器作为全光分路时钟提取及波长转换器,数值模拟实现了从波长为1555 nm、速率为2×20 Gb/s的光时分复用信号中提取出波长转换为1550 nm、重复频率为20 GHz的分路光时钟,实验完成了从波长为155024 nm、重复频率为1236 GHz光脉冲信号中提取出相位噪声为-105 dBc/Hz的波长为154591 nm、重复频率618 GHz的分频光时钟.此外还详细研究了注入光功率、波长失谐、FP激光器偏置电流及纵模选择对光时钟提取的影响,实验结果和数值模拟结果符合.该方法在光时分复用混合波分复用通信系统中实现全光解复用及波长路由有着重要的应用价值.
关键词:
波长转换
时钟提取
光注入
非线性动力学 相似文献
70.
This work aims to obtain a wide area differential method for geostationary orbit (GEO) constellation. A comparison between
the dilution of precision (DOP) of four-dimensional (4D) calculation including satellite clock errors and ephemeris errors
and that of three-dimensional (3D) calculation only including ephemeris errors with the inverse positioning theory of GPS
shows the conclusion that all the 3D PDOPs are greatly reduced. Based on this, a basic idea of correcting satellite clock
errors and ephemeris errors apart is put forward, and moreover, a specific method of separation is proposed. Satellite clock
errors are separated in a master station with time synchronization, and all the remaining pseudo-range errors after the satellite
clock errors have been deducted are used to work out ephemeris corrections of all GEO satellites. By a comparative analysis
of user positioning accuracy before and after differential, the wide area differential method is verified to be quite valid
for GEO constellation.
Supported by the National Natural Science Foundation of China (Grant No. 10778715), the National Key Basic Research Development
Program of China (Grant No. 2007CB815502), and the Scientific Research Fund of Hunan Provincial Education Department (Grant
No. 08B039) 相似文献