Beijing National Data Center

Beijing, China

Beijing National Data Center

Beijing, China
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Yao Z.,Tsinghua University | Liu L.,Beijing National Data Center | Zhang X.,Tsinghua University | Lu M.,Tsinghua University
Wuhan Daxue Xuebao (Xinxi Kexue Ban)/Geomatics and Information Science of Wuhan University | Year: 2012

We present a kind of signal performance evaluation method for generic mismatch processing mode. On this basis, four reference modulations for compass B1 band interoperable signal are proposed, and within which, an optimal reference modulation is given based on the comprehensive performance. Compared with existing interoperable signals, the proposal modulation has independent intellectual property right. And it has superiorities in demodulation and tracking, as well as in the flexibility. The experimental results can be regarded as a feasible reference for the design and optimization of the compass signals.


Chen Z.-Y.,Tsinghua University | Chen Z.-Y.,Beijing National Data Center | Liu S.-J.,Beijing National Data Center | Wang J.-L.,Tsinghua University | Chang Y.-Z.,Beijing National Data Center
Fenxi Huaxue/ Chinese Journal of Analytical Chemistry | Year: 2016

Volume concentration determination of atmospheric krypton and xenon is very important for krypton-85 and radioactive xenon isotopes monitoring. An injection set-up integrated adjustable quantity sample injection and quantitative dilution function was designed. The effects of electron impact (EI) source parameters on the sensitivity of MS detector were studied. Optimal values were as follows: ionization energy of 70 eV, emission current of 40 mA, cathode voltage of 27 mV, ion focus voltage of 85 mV and lens compensation voltage of 20 V. A GC-MS method for the determination of krypton and xenon in atmosphere without sample pretreatment was developed. Minimal detected concentrations for krypton and xenon were 3.3 × 10-8 (V/V) and 2.6 × 10-9 (V/V) respectively. Moreover, krypton and xenon concentrations in the ground level air were measured with the results of 1.1 × 10-6 (V/V) and 9.3 × 10-8 (V/V). The related combined standard uncertainties for krypton and xenon results were 2.38% and 3.15%, respectively. © 2016 Changchun Institute of Applied Chemistry, Chinese Academy of Sciences.


Chen Z.-Y.,Beijing National Data Center | Chang Y.-Z.,Beijing National Data Center | Liu S.-J.,Beijing National Data Center | Zhang H.-T.,Northwest Institute of Nuclear Technology | And 2 more authors.
Chemical Research in Chinese Universities | Year: 2012

A pulse-discharge helium ionization detector(Valco, PD-D3-I) was used to measure xenon concentration in air. The dependences of the detector relative response on various gas chromatograph parameters were investigated. Based on the well prepared gas connections for the detector system and optimized gas chromatography(GC) working conditions, the atmospheric xenon concentration could be measured by the cheap GC method with a detection level of 0.7×10-9(parts by volume). Moreover, the xenon concentration in the ground level air around our laboratory was measured with the result of 0.085×10-6(parts by volume) and RSD of 0.91%.


Li J.,Beijing National Data Center | Li J.,Post University | Wang X.-M.,Beijing National Data Center | Shi J.-F.,Beijing National Data Center | And 2 more authors.
Hedianzixue Yu Tance Jishu/Nuclear Electronics and Detection Technology | Year: 2014

Polarization analysis is used on 3-Component stations data to estimate the azimuth and slowness at CTBT BeiJing NDC. In order to improve the quality of azimuth estimation, in this work, polarization analysis was conducted in the detection filter band in addition to the original fixed band. The testing shows the method effectively enhanced the quality of polarization analysis for arrivals with energy only covering a narrow frequency and for regional arrivals located in a higher frequency band. The accuracy of the azimuths estimation was improved. The new approach was not effective for stations without normal distribution of azimuth residuals. ©, 2014, Atomic Energy Press. All right reserved.


Jia H.-M.,Beijing National Data Center | Wang S.-L.,Beijing National Data Center | Wang J.,Beijing National Data Center | Li Q.,Beijing National Data Center | And 3 more authors.
Yuanzineng Kexue Jishu/Atomic Energy Science and Technology | Year: 2010

The β-γ coincidence technique is a kind of the key important method to detect radioactive xenon isotopes for the Comprehensive Nuclear-Test-Ban Treaty (CTBT). This paper describes noble gases memory effects of β-γ coincidence detector. Xenon memory effects were measured and its influence on detector's minimum detectable activity (MDA) was evaluated. The methods of reducing xenon memory effects were studied. In conclusion, aluminium coated plastic scintillator and YAP scintillator can remarkably decrease xenon memory effects.


Li Q.,Beijing National Data Center | Wang S.,Beijing National Data Center | Jia H.,Beijing National Data Center | Fan Y.,Beijing National Data Center | And 5 more authors.
Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment | Year: 2013

The gamma ray emission probability is one of the most important characteristics used in quantifying radionuclides. This article describes in detail the principles and processes involved in the determination of the 135Xe gamma ray emission probability. Gaseous samples of 135Xe were generated by irradiating enriched 134Xe with a thermal neutron flux. The principal gamma ray emission probability of 135Xe was then determined to be 0.896±0.016 (k=1) by measuring the absolute activity using length-compensated internal gas proportional counters and γ-ray intensity using a high-purity germanium (HPGe) detector. © 2012 Elsevier B.V.


Shang J.,Beijing National Data Center | Liu J.-M.,Beijing National Data Center | Xu Z.-Y.,Beijing National Data Center | Gai L.,Beijing National Data Center | Wang X.-M.,Beijing National Data Center
Hedianzixue Yu Tance Jishu/Nuclear Electronics and Detection Technology | Year: 2011

To improve the monitoring capability for some sensitive areas constantly, the CTBT Beijing national data center (NDC) needs to obtain more and more data of seismic stations via Internet. A multi-source data collection program pacakge is prensented. The program can fetch seismic monitoring data from different network centers or data sources nearly in real-time in different ways, and then sort data by time, discard the redundant and convert them to CSS format. With this program, NDC can reliably obtain monitoring data of some seismic stations in time.


Shang J.,Beijing National Data Center | Wang H.,Beijing National Data Center | Gai L.,Beijing National Data Center | Xu Z.-Y.,Beijing National Data Center | Liu J.-M.,Beijing National Data Center
Hedianzixue Yu Tance Jishu/Nuclear Electronics and Detection Technology | Year: 2011

The CTBT Beijing national data center (NDC) plays an important role in China CTBT verification system, which require a stable, reliable data transport links to access the monitoring stations in order to protect the routine analysis and monitoring capabilities. A data transfer program, which can collect data from the LISS source or EDAS-24IP devices on the stations to generate CD1.1 format data and use CD1.1 protocol to transfer data to NDC in near real time is presented. The program is currently being implemented on some stations of the monitoring system.


Shu-Jiang L.,Beijing National Data Center | Zhan-Ying C.,Beijing National Data Center | Yin-Zhong C.,Beijing National Data Center | Shi-Lian W.,Beijing National Data Center | And 5 more authors.
Analyst | Year: 2015

In the research of xenon sampling and xenon measurements, the xenon breakthrough curve plays a significant role in the xenon concentrating dynamics. In order to improve the theoretical comprehension of the xenon concentrating procedure from the atmosphere, the method of the breakthrough curve combination for sampling techniques should be developed and investigated under pulse injection conditions. In this paper, we describe a xenon breakthrough curve in a carbon molecular sieve column, the combination curve method for five conditions is shown and debated in detail; the fitting curves and the prediction equations are derived in theory and verified by the designed experiments. As a consequence, the curves of the derived equations are in good agreement with the fitting curves by tested. The retention times of the xenon in the column are 61.2, 42.2 and 23.5 at the flow rate of 1200, 1600 and 2000 mL min-1, respectively, but the breakthrough times are 51.4, 38.6 and 35.1 min. © 2014 The Royal Society of Chemistry.


Xu C.-Y.,Beijing National Data Center | Liu J.-M.,Beijing National Data Center | Shang J.,Beijing National Data Center | Gai L.,Beijing National Data Center | And 3 more authors.
Hedianzixue Yu Tance Jishu/Nuclear Electronics and Detection Technology | Year: 2012

Functions of open-source spider wget, which is used to get network resource, are introduced in this paper. Study on automatic acquisition technique of network resource is depicted, automatic acquisition of National Oceanic and Atmospheric Administrtation's network resource is presented and implemented. It is indicated that automatic acquisition technique can acquire network resource during a long time test and practical application.

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