检索结果-南通市图书馆

The Multi-parameter Test of Gravitational Wave Dispersion with Principal Component Analysis

在线全文

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2024年第5期24卷 140-150页

作者： zhi-chu Ma Rui Niu Wen Zhao CAS Key Laboratory for Research in Galaxies and Cosmology Department of AstronomyUniversity of Science and Technology of ChinaHefei 230026China School of Astronomy and Space Sciences University of Science and Technology of ChinaHefei 230026China

In this work, we consider a conventional test of gravitational wave(GW) propagation which is based on the phenomenological parameterized dispersion relation to describe potential departures from General Relativity(GR)along the propagation of GWs. But different from tests conventionally performed previously, we vary multiple deformation coefficients simultaneously and employ the principal component analysis(PCA) method to remedy the strong degeneracy among deformation coefficients and obtain informative posteriors. The dominant PCA components can be better measured and constrained, and thus are expected to be more sensitive to potential departures from the waveform model. Using this method we analyze ten selected events and get the result that the combined posteriors of the dominant PCA parameters are consistent with GR within 99.7% credible intervals. The standard deviation of the first dominant PCA parameter is three times smaller than that of the original dispersion parameter of the leading order. However, the multi-parameter test with PCA is more sensitive to not only potential deviations from GR but also systematic errors of waveform models. The difference in results obtained by using different waveform templates hints that the demands of waveform accuracy are higher to perform the multiparameter test with PCA. Whereas, it cannot be strictly proven that the deviation is indeed and only induced by systematic errors. It requires more thorough research in the future to exclude other possible reasons in parameter estimation and data processing.

关键词： gravitational waves-gravitation-black hole physics

Anisotropic Fractional Brownian Random Fields as White Noise Functionals

在线全文

学校读者我要写书评

暂无评论

Acta Mathematicae Applicatae Sinica 2005年第4期21卷 655-660页

作者： zhi-yuan Huang chu-jin Li Department of Mathematics Huazhong University of Science & Technology Wuhan 430074 China

This investigation aims at a new construction of anisotropic fractional Brownian random fields by the white noise approach. Moreover, we investigate its distribution and sample properties （stationariness of increment... 详细信息

关键词： Riesz poly-potential anisotropic fields fractional Brownian motion white noise functionals

Injection transient study using a two-frequency bunch length measurement system at the SSRF

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Nuclear Science and Techniques 2017年第7期28卷 37-42页

作者： Li-Wu Duan Yong-Bin Leng Ren-Xian Yuan zhi-chu Chen Shanghai Institute of Applied Physics Chinese Academy of Sciences Shanghai 201800 China Shanghai Synchrotron Radiation Facility Chinese Academy of Sciences Zhangjiang Campus Shanghai 201204 China

The bunch length can be measured by comparison of two frequency components of a synchrotron beam *** online bunch length measurement system has been implemented based on this *** frequencies of 3 GHz and 500 MHz were selected,and the raw data was acquired by digital oscilloscope and was resampled and analyzed using the MATLAB software platform at bunch-by-bunch *** constructed system was employed to study the bunch length synchronous oscillation phenomenon during *** beam experiments demonstrated a time resolution of less than 0.5 ps.

关键词：长度测量系统束团长度注射过程双频光源上海瞬态 Matlab

Fractional Brownian Motion and Sheet as White Noise Functionals

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2006年第4期22卷 1183-1188页

作者： zhi Yuan HUANG chu Jin LI Jian Ping WAN Ying WU Department of Mathematics Huazhong University of Science and Technology Wuhan 430074 P. R. China

In this short note, we show that it is more natural to look the fractional Brownian motion as functionals of the standard white noises, and the fractional white noise calculus developed by Hu and Фksendal follows directly from the classical white noise functional calculus. As examples we prove that the fractional Girsanov formula, the Ito type integrals and the fractional Black-Scholes formula are easy consequences of their classical counterparts. An extension to the fractional Brownian sheet is also briefly discussed.

关键词： Fractional Brownian motion Fractional white noise functionals Fractional Girsanov formula Wick product

A NEW TECHNIQUE OF OIL TRANSPORTATION IN PIPELINE BY STEAM INJECTION

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2002年第4期14卷 1-6页

作者： Lai, Ying-Xu Zheng, zhi-chu Shi, Zai-Hong Wu, Ying-Xiang Inst. of Mech. Chinese Acad. of Sci. Beijing 100080 China

The direct contact heating of crude oil with steam is a promising technique for improving crude oil transportation in pipelines. Crude oil temperature is increased greatly by a small quantity of steam due to the high steam latent heat and direct contact heat transfer. A jet pump was developed for injecting steam into oil in order to get a high efficiency by transferring momentum and energy from a high-velocity jet to ambient fluid. The jet pump was designed based on the free injection principle, which has no rotation parts and no converging mixing chamber, therefore it would not be blocked by the viscous crude oil. The technical feasibility of this method has been tested in the Liaohe Oilfield of China.

关键词： Crude petroleum Heat transfer Jet pumps Steam

On-line optical determination of floc size of Fe(Ⅲ) coagulants

在线全文

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2005年第6期17卷 921-925页

作者： WANG Yan GAO Bao-yu YUE Qin-yan ZHOU Wei-zhi chu Yong-bao School of Environmental Science and Engineering Shandong University Jinan 250100 China

This study investigated the floc aggregation, average floc size, floc size variance and floc growth velocity when ferric chloride （FeCl3） and polyferric chloride （PFC） were used to treat the simulated water samples. The factors including coagulant dose, ionic strength and solution pH, which affect the floc aggregation, were studied. Experiments were carried out in a bench-scale reactor using photometric dispersion analyzer （ PDA）. Results showed that there were great differences between the floc aggregation of PFC and FeCl3. The average floc size and fioc growth velocity of PFC were much larger than those of FeCl3. Compared with FeCl3, PFC gave a better coagulation performance in wider range of pH, dosage and ionic strength. It was also found that the coagulation efficiency of PFC did not depend on average floc size but on floc growth velocity.

关键词： coagulants photometric dispersion analyzer(PDA) floc aggregation water treatment

Numerical model establishment and verification of cold pilgering on cycle feed rate

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2018年第4期25卷 398-408页

作者： zhi-bing chu Dong Wei Lian-yun Jiang Duo Zhang Qing-xue Huang Yu-gui Li Heavy Machinery Engineering Research Center of Ministry of Education Taiyuan University of Science and Technology Taiyuan 030024 Shanxi China Shanxi Provincial Key Laboratory of Metallurgical Device Design Theory and Technology Taiyuan University of Science and Technology Taiyuan 030024 Shanxi China

A numerical model was established to calculate the cycle feed rate through studying the case of a cold pilger mill with the 304 stainless steel pipe. Firstly, the precise constitutive equation of 304 stainless steel was obtained through nonlinearly fitting the true stress-strain data from unidirectional tensile test. Then, the numerical method to calculate the equivalent deformation was determined according to the plastic deformation feature of the steel tube during cold rolling and the incremental theory. Finally, the cycle feed rate of cold roiled 304 stainless steel pipe was extracted when formulating springback through utilizing above results comprehensively and unloading law. Stress state, metal flow, finished pipe size and distribution of residual stress were obtained by finite element method to calculate the whole rolling process when the cycle feed rate was 10 mm, and the optimized model was verified through finished pipe size.

关键词： Cycle feed rate Cold pilgering 304 stainless steel pipe Constitutive relationship Incremental theory Unloading law Residual stress experiment

Development of the bunch-by-bunch beam position acquisition system based on BEEcube

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Nuclear Science and Techniques 2016年第2期27卷 86-91页

作者： Yong Yang Yong-Bin Leng Ying-Bing Yan Wei-Min Zhou Ren-Xian Yuan zhi-chu Chen Shanghai Institute of Applied Physics Chinese Academy of Sciences Shanghai 201800 China University of Chinese Academy of Sciences Beijing 100049China

In this paper, we report the development of a bunch-by-bunch beam position acquisition *** a wideband synthesizer of PLL, the system realizes synchronous clock of bunch signal. Based on the highperformance FPGA hardware DAQ environment, fourchannel raw data of beam signal can be achieved. Test results in the SSRF storage ring show that the system can obtain beam position of single bunch with the resolution of10 lm and multi-bunch instability can be observed.

关键词：采集系统束流位置基础同步时钟数据采集 FPGA 原始数据合成器

OIL-WATER TWO-PHASE FLOW INSIDE T-JUNCTION

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2008年第2期20卷 147-153页

作者： WANG Li-yang WU Ying-xiang ZHENG zhi-chu GUO Jun ZHANG Jun TANG Chi Laboratory of Applied Fluid Dynamics Department of Engineering Science Institute of Mechanics Chinese Academy of Sciences Beijing 100190 China

The oil / water two-phase flow inside T-junctions was numerically simulated with a 3-D two-fluid model, and the turbulence was described using the mixture k- ε model. Some experiments of oil / water flow inside a single T-junction were conducted in the laboratory. The results show that the separating performance of T-junction largely depends on the inlet volumetric fraction and flow patterns. A reasonable agreement is reached between the numerical simulation and the experiments for both the oil fraction distribution and the separation efficiency.

关键词： T-junction two-phase flow liquid / liquid separation numerical simulation