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Investigating the Relationship between TyG, TyG-BMI Index and Laboratory Indicators and COVID-19 Severity
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作者 Cai Liang Huaiwu Jiang +3 位作者 Feng Pu Jing Lin weijia sun Yun Zhou 《Advances in Infectious Diseases》 2023年第4期641-651,共11页
Objective: The objective of this study was to investigate the relationship between the triglyceride-glucose (TyG) index, triglyceride-glucose-BMI (TyG-BMI) index, laboratory indices, and disease severity in patients w... Objective: The objective of this study was to investigate the relationship between the triglyceride-glucose (TyG) index, triglyceride-glucose-BMI (TyG-BMI) index, laboratory indices, and disease severity in patients with COVID-19. Methods: A retrospective analysis of COVID-19 patients treated at a tertiary hospital in Mianyang City, Sichuan Province, China, from 1 May to 31 May 2023 was performed. The patients were divided into two groups: 66 cases in the moderate group and 61 cases in the severe group. Additionally, 69 uninfected individuals from the medical examination center during the same period were selected as the control group. Spearman rank correlation was used to determine the correlation between the indices and COVID-19 severity. Multiple logistic regression analysis was performed to identify the factors affecting COVID-19 severity. ROC curves were constructed to assess the predictive value of the TyG and TyG-BMI indices for severe COVID-19. Results: There were significant differences in smoking and diabetes between the three groups (P Conclusion: Smoking, AST, ALB, TyG index, and TyG-BMI index are valuable in assessing the severity of COVID-19, with the TyG-BMI index having a higher predictive value than the TyG index. 展开更多
关键词 COVID-19 TyG Index TyG-BMI Index SEVERITY Liver Function
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The mechanosensitive lncRNA Neat1 promotes osteoblast function through paraspeckle-dependent Smurf1 mRNA retention 被引量:9
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作者 Caizhi Liu Xingcheng Gao +22 位作者 Yuheng Li weijia sun Youjia Xu Yingjun Tan Ruikai Du Guohui Zhong Dingsheng Zhao Zizhong Liu Xiaoyan Jin Yinlong Zhao Yinbo Wang Xinxin Yuan Junjie Pan Guodong Yuan Youyou Li Wenjuan Xing Guanghan Kan Yanqing Wang Qi Li Xuan Han Jianwei Li Shukuan Ling Yingxian Li 《Bone Research》 SCIE CAS CSCD 2022年第2期338-353,共16页
Mechanical stimulation plays an important role in bone remodeling. Exercise-induced mechanical loading enhances bone strength,whereas mechanical unloading leads to bone loss. Increasing evidence has demonstrated that ... Mechanical stimulation plays an important role in bone remodeling. Exercise-induced mechanical loading enhances bone strength,whereas mechanical unloading leads to bone loss. Increasing evidence has demonstrated that long noncoding RNAs(lnc RNAs) play key roles in diverse biological, physiological and pathological contexts. However, the roles of lnc RNAs in mechanotransduction and their relationships with bone formation remain unknown. In this study, we screened mechanosensing lnc RNAs in osteoblasts and identified Neat1, the most clearly decreased lnc RNA under simulated microgravity. Of note, not only Neat1 expression but also the specific paraspeckle structure formed by Neat1 was sensitive to different mechanical stimulations, which were closely associated with osteoblast function. Paraspeckles exhibited small punctate aggregates under simulated microgravity and elongated prolate or larger irregular structures under mechanical loading. Neat1 knockout mice displayed disrupted bone formation, impaired bone structure and strength, and reduced bone mass. Neat1 deficiency in osteoblasts reduced the response of osteoblasts to mechanical stimulation. In vivo, Neat1 knockout in mice weakened the bone phenotypes in response to mechanical loading and hindlimb unloading stimulation. Mechanistically, paraspeckles promoted nuclear retention of E3 ubiquitin ligase Smurf1 m RNA and downregulation of their translation, thus inhibiting ubiquitination-mediated degradation of the osteoblast master transcription factor Runx2, a Smurf1 target. Our study revealed that Neat1 plays an essential role in osteoblast function under mechanical stimulation, which provides a paradigm for the function of the lnc RNA-assembled structure in response to mechanical stimulation and offers a therapeutic strategy for long-term spaceflight-or bedrest-induced bone loss and age-related osteoporosis. 展开更多
关键词 STIMULATION MEC IMPAIRED
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荧光法测定菠菜焯水过程中维生素B_(2)的流失——荧光法测定维生素B_(2)的实验拓展
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作者 黄洋祺 李誉 +7 位作者 李常耕 朱颜 孙维嘉 范春涵 李琰 丁飞 张晓光 孔德明 《大学化学》 CAS 2023年第10期274-279,共6页
“荧光法测定维生素B_(2)(VB_(2))的含量”是本科生仪器分析教学中一个常用实验,但存在实验内容偏少、学生锻炼不足等问题。菠菜是一种VB_(2)含量较高的绿色蔬菜,但食用前焯水去除草酸的过程不可避免地造成VB_(2)的部分流失。本实验在... “荧光法测定维生素B_(2)(VB_(2))的含量”是本科生仪器分析教学中一个常用实验,但存在实验内容偏少、学生锻炼不足等问题。菠菜是一种VB_(2)含量较高的绿色蔬菜,但食用前焯水去除草酸的过程不可避免地造成VB_(2)的部分流失。本实验在证明荧光法可用于测定菠菜焯水过程中VB_(2)析出量的基础上,提出将不同焯水时间下VB_(2)流失率的测定丰富到本科实验的教改思路。该思路不仅极大地丰富了原有的实验内容,而且新颖有趣、贴近生活,既可提升学生的学习兴趣,又有助于帮助学生培养学以致用的能力。 展开更多
关键词 实验教学改革 荧光 维生素B_(2) 菠菜 拓展实验
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Detection of seismic events on Mars: a lunar perspective 被引量:2
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作者 weijia sun Liang Zhao +1 位作者 Yong Wei Li-Yun Fu 《Earth and Planetary Physics》 CSCD 2019年第4期290-297,共8页
The interior structures of planets are attracting more and more detailed attention;these studies could be of great value in improving our understanding of the early evolution of Earth. Seismological investigations of ... The interior structures of planets are attracting more and more detailed attention;these studies could be of great value in improving our understanding of the early evolution of Earth. Seismological investigations of planet interiors rely primarily on seismic waves excited by seismic events. Since tectonic activities are much weaker on other planets, e.g. Mars, the magnitudes of their seismic events are much smaller than those on Earth. It is therefore a challenge to detect seismic events on planets using such conventional techniques as short-time average/long-time average (STA/LTA) triggers. In pursuit of an effective and robust scheme to detect smallmagnitude events on Mars in the near future, we have taken Apollo lunar seismic observations as an example of weak-activity data and developed an event-detection scheme. The scheme reported here is actually a two-step processing approach: the first step involves a despike filter to remove large-amplitude impulses arising from large temperature variations;the second step employs a matched filter to unmask the seismic signals from a weak event hidden in the ambient and scattering noise. The proposed scheme has been used successfully to detect a moonquake that was not in the known moonquake catalogue, demonstrating that the two-step strategy is a feasible method for detecting seismic events on planets. Our scheme will provide a powerful tool for seismic data analysis of the Interior Exploration using Seismic Investigations, Geodesy and Heat Transport (InSight) mission, and China’s future lunar missions. 展开更多
关键词 PLANETARY SEISMOLOGY event DETECTION INTERIOR structures despike FILTER matched FILTER
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HuR-mediated nucleocytoplasmic translocation of HOTAIR relieves its inhibition of osteogenic differentiation and promotes bone formation 被引量:2
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作者 Yuheng Li weijia sun +15 位作者 Jianwei Li Ruikai Du Wenjuan Xing Xinxin Yuan Guohui Zhong Dingsheng Zhao Zizhong Liu Xiaoyan Jin Junjie Pan Youyou Li Qi Li Guanghan Kan Xuan Han Shukuan Ling Xiqing sun Yingxian Li 《Bone Research》 SCIE CAS CSCD 2023年第4期803-818,共16页
Bone marrow mesenchymal stem cell(BMSC)osteogenic differentiation and osteoblast function play critical roles in bone formation,which is a highly regulated process.Long noncoding RNAs(lncRNAs)perform diverse functions... Bone marrow mesenchymal stem cell(BMSC)osteogenic differentiation and osteoblast function play critical roles in bone formation,which is a highly regulated process.Long noncoding RNAs(lncRNAs)perform diverse functions in a variety of biological processes,including BMSC osteogenic differentiation.Although several studies have reported that HOX transcript antisense RNA(HOTAIR)is involved in BMSC osteogenic differentiation,its effect on bone formation in vivo remains unclear.Here,by constructing transgenic mice with BMSC(Prx1-HOTAIR)-and osteoblast(Bglap-HOTAIR)-specific overexpression of HOTAIR,we found that Prx1-HOTAIR and Bglap-HOTAIR transgenic mice show different bone phenotypes in vivo.Specifically,Prx1-HOTAIR mice showed delayed bone formation,while Bglap-HOTAIR mice showed increased bone formation.HOTAIR inhibits BMSC osteogenic differentiation but promotes osteoblast function in vitro.Furthermore,we identified that HOTAIR is mainly located in the nucleus of BMSCs and in the cytoplasm of osteoblasts.HOTAIR displays a nucleocytoplasmic translocation pattern during BMSC osteogenic differentiation.We first identified that the RNA-binding protein human antigen R(HuR)is responsible for HOTAIR nucleocytoplasmic translocation.HOTAIR is essential for osteoblast function,and cytoplasmic HOTAIR binds to miR-214 and acts as a ceRNA to increase Atf4 protein levels and osteoblast function.BglapHOTAIR mice,but not Prx1-HOTAIR mice,showed alleviation of bone loss induced by unloading.This study reveals the importance of temporal and spatial regulation of HOTAIR in BMSC osteogenic differentiation and bone formation,which provides new insights into precise regulation as a target for bone loss. 展开更多
关键词 HOTAIR PRECISE function
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Determination of the Contents of Seven Chemical Components in Vidal Grape by Quantitative Analysis of Multi-components by Single Marker(QAMS) 被引量:1
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作者 Shizhao XU Fei QI +2 位作者 Yalin XI Ling WU weijia sun 《Agricultural Biotechnology》 CAS 2020年第6期131-135,共5页
[Objectives]This study was conducted to establish a method of quantitative analysis of multi-components by single marker(QAMS)for the simultaneous determination of such seven chemical components as gallic acid,epicate... [Objectives]This study was conducted to establish a method of quantitative analysis of multi-components by single marker(QAMS)for the simultaneous determination of such seven chemical components as gallic acid,epicatechin,catechin,ferulic acid,chlorogenic acid,rutin and caffeic acid in Vidal grape.[Methods]The high performance liquid chromatography was carried out using a COSMOSIL C18-MS-II column(4.6 mm×250 mm,5μm)with the mobile phase acetonitrile-2%acetic acid aqueous solution(gradient elution)at a flow rate of 1.0 ml/min.The detection wavelength was 280 nm,and the column temperature was 25℃.Using caffeic acid as an internal reference,the relative correction factors between it and other six to-be-detected components,and the contents of the seven components were calculated using the correction factors.The established was compared the results with the external standard method to verify the feasibility and accuracy of the method.[Results]The seven components had a good linear relationship in the ranges of 1.060-10.60,1.419-14.19,1.062-10.62,0.2950-2.950,0.1019-1.019,0.2014-2.014,and 0.1498-1.498μg,respectively,and the relative correction factors of gallic acid,epicatechin,catechin,ferulic acid,chlorogenic acid and rutin were 0.9760,0.7806,0.3277,1.640,1.161,2.778,respectively.There was no significant difference between the results of the QAMS method and the external standard method.[Conclusions]The QAMS method using caffeic acid as an internal reference is accurate and feasible,and provides a reliable method for the quality evaluation of Vidal ice grape. 展开更多
关键词 High performance liquid chromatography Vidal grape Content determination Polyphenol compounds
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Acoustic viscoelastic modeling by frequency-domain boundary element method 被引量:1
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作者 Xizhu Guan Li-Yun Fu weijia sun 《Earthquake Science》 CSCD 2017年第2期97-105,共9页
Earth medium is not completely elastic, with its viscosity resulting in attenuation and dispersion of seismic waves. Most viscoelastic numerical simulations are based on the finite-difference and finite-element method... Earth medium is not completely elastic, with its viscosity resulting in attenuation and dispersion of seismic waves. Most viscoelastic numerical simulations are based on the finite-difference and finite-element methods. Targeted at viscoelastic numerical modeling for multilayered media, the constant-Q acoustic wave equation is transformed into the corresponding wave integral representation with its Green's function accounting for viscoelastic coefficients. An efficient alternative for full-waveform solution to the integral equation is proposed in this article by extending conventional frequency-domain boundary element methods to viscoelastic media. The viscoelastic boundary element method enjoys a distinct characteristic of the explicit use of boundary continuity conditions of displacement and traction, leading to a semi-analytical solution with sufficient accuracy for simulating the viscoelastic effect across irregular interfaces. Numerical experiments to study the viscoelastic absorption of different Q values demonstrate the accuracy and applicability of the method. 展开更多
关键词 Viscoelastic media Viscoelastic boundary element method Frequency-domain implementation Viscoelastic numerical modeling
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澳大利亚大陆上地幔顶部的速度结构:Pn走时层析成像
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作者 weijia sun B.L.N.Kennett +1 位作者 孙伟家(译) 朱玉萍(校) 《世界地震译丛》 2017年第2期150-168,共19页
澳大利亚大陆的地震速度结构多以面波层析成像、地震折射、接收函数和噪声层析成像为主。澳大利亚大陆的三维速度结构已被总结成澳大利亚地震参考模型(AuSREM)。Pn波走时层析成像可提供整个该大陆更强约束的上地幔结构信息。本文调查了... 澳大利亚大陆的地震速度结构多以面波层析成像、地震折射、接收函数和噪声层析成像为主。澳大利亚大陆的三维速度结构已被总结成澳大利亚地震参考模型(AuSREM)。Pn波走时层析成像可提供整个该大陆更强约束的上地幔结构信息。本文调查了自1993年以来发生在澳大利亚大陆内部大的地震事件的波形和地震震相报告,这些地震事件被固定台站和流动台站所记录。为克服澳大利亚东西部大的横向速度对比和保证震源参数的一致性,所有的地震事件在三维澳大利亚参考速度模型中进行了地震重定位。地震重定位后发现,地震震相的走时残差特征具有良好的一致性。定义Pn波为震中距1.8~15°范围内的初至波。利用FMTOMO方法反演走时差以获得上地幔顶部的P波速度结构,其分辨率为3°×3°。反演结果表明,整个澳大利亚大陆上地幔顶部P波速度呈强烈的横向不均匀性。P波的最大速度为8.36km/s,位于澳大利亚西部和中部的前寒武纪克拉通下方,其比全球ak135模型的P波速度快3.99%;最慢的P波速度为7.66km/s,其位于澳大利亚大陆东缘显生宙造山带之下,较全球ak135模型慢4.74%,这可能与晚第三纪火山活动有关。 展开更多
关键词 澳大利亚大陆上地幔Pn波速度模型 在整个该大陆Pn波速度具有强横向不均匀性 P波结构比以前发现的长周期S波更复杂
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Comparison of crustal and upper mantle heterogeneity in different time periods: Indonesian subduction zone to northern Australia
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作者 weijia sun Li-Yun Fu B.L.N.Kennett 《Earthquake Science》 2014年第1期47-55,共9页
Earthquake events from the Indonesian subduction zone recorded in northern Australia show a long and high-frequency coda associated with both P and S waves. Regional events recorded by Warramunga array in northern Aus... Earthquake events from the Indonesian subduction zone recorded in northern Australia show a long and high-frequency coda associated with both P and S waves. Regional events recorded by Warramunga array in northern Australia can separate out wave propagation through the mantle by focusing on the coherent signal across the medium-aperture array. Most of the incoherent wave components result from structures in the vicinity of the array with small-scale lengths of 1-2 km or smaller. The coherent phases with relatively rapid changes in waveforms are associated with the scattering of seismic waves by crustal and mantle heterogeneity, but in some case can be related to structural effects near the source. As the depth of the source increases, the coherent portion of the seismic wavefield tends to become much simpler, which suggests that the heterogeneity tends to weaken at depth with larger-scale length. We compare the coherent signal features of earthquakes from the Indonesian subduction zone that have occurred in recent years with those in the early 1980s, first studied by Kennett (Phys Earth Planet Inter 47: 319-332, 1987). The general characteristics of the coherent signal variation with depth in recent years are the same as those observed in 1980s, but the variations are larger. This change suggests a stringer var- iation in heterogeneity with depth than before, which may bear important information about the dynamic processes and evolution of the crust and upper mantle. 展开更多
关键词 CRUST Mantle HETEROGENEITY
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我国深空探测研究深入火星和月球内部 被引量:1
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作者 孙伟家 魏勇 《科学通报》 EI CAS CSCD 北大核心 2023年第6期573-575,共3页
地球、火星、月球等具有显著的圈层结构,这是其形成与演化的结果;圈层结构因而记录了它们的形成和演化中诸多地质过程和环境变迁,如岩浆洋冷却、壳幔分异和核幔分异,以及气候和宜居性环境演变等.地球的圈层结构可分为外部圈层(水圈、生... 地球、火星、月球等具有显著的圈层结构,这是其形成与演化的结果;圈层结构因而记录了它们的形成和演化中诸多地质过程和环境变迁,如岩浆洋冷却、壳幔分异和核幔分异,以及气候和宜居性环境演变等.地球的圈层结构可分为外部圈层(水圈、生物圈、大气圈)和内部圈层(地壳、地幔、地核),地球各圈层间存在大规模的物质循环和能量交换.地壳物质可以通过俯冲过程到达地幔甚至是核幔边界,而核幔边界的热物质则能以地幔柱形式上涌至地表.本文着重探讨火星与月球的浅表层和深部结构探测及其未来可能的考量. 展开更多
关键词 圈层结构 核幔边界 地质过程 大气圈 物质循环 能量交换 宜居性 环境变迁
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同源罗伯逊易位型21-三体家系的遗传学规律:12个家系分析
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作者 孙惟佳 刘天盛 +2 位作者 黄红倩 费冬梅 罗静思 《中华围产医学杂志》 CAS CSCD 北大核心 2023年第11期941-945,共5页
目的总结同源罗伯逊易位型21-三体家系的遗传规律。方法回顾性纳入2012年1月至2023年1月在广西壮族自治区妇幼保健院经产前诊断确诊胎儿为同源罗伯逊易位型21-三体[46,XX/XY,+21,der(21;21)(q10;q10)]且夫妇双方完成外周血染色体核型分... 目的总结同源罗伯逊易位型21-三体家系的遗传规律。方法回顾性纳入2012年1月至2023年1月在广西壮族自治区妇幼保健院经产前诊断确诊胎儿为同源罗伯逊易位型21-三体[46,XX/XY,+21,der(21;21)(q10;q10)]且夫妇双方完成外周血染色体核型分析的12个家系(母亲均为单胎妊娠)。总结其产前诊断结果及遗传规律。采用描述性统计分析。结果12个家系中,夫妇双方均为正常核型的新发家系8个;遗传性家系4个,均为母源性,其中1例母亲为21号染色体同源罗伯逊易位携带者,另3例母亲为同源罗伯逊易位型21-三体综合征患者,4个家系父亲核型均正常。有3个家系生育多个子女,其中2个父母核型正常的家系曾经生育过正常核型子代,1例母亲为同源罗伯逊易位型21-三体综合征患者的家系前次妊娠生育同型21-三体患儿。2个家系母亲本次妊娠行无创产前检测,1例21-三体低风险,引产胎盘检测显示低比例嵌合型21-三体(胎盘母体面嵌合比例为21%,胎盘子面为9%);另1例为21-三体高风险。结论同源罗伯逊易位型21-三体多为新发病例,少部分为遗传性。对于曾生育过同源罗伯逊易位型21-三体患者的家系应常规建议父母进行外周血染色体检查,了解父母是否为同源罗伯逊易位携带者。 展开更多
关键词 染色体 21对 唐氏综合征 系谱 易位 遗传 产前诊断 核型分析
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Elastic wave propagation and scattering in prestressed porous rocks 被引量:3
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作者 Li-Yun FU Bo-Ye FU +2 位作者 weijia sun Tongcheng HAN Jianlin LIU 《Science China Earth Sciences》 SCIE EI CAS CSCD 2020年第9期1309-1329,共21页
Poro-acoustoelastic theory has made a great progress in both theoretical and experimental aspects,but with no publications on the joint research from theoretical analyses,experimental measurements,and numerical valida... Poro-acoustoelastic theory has made a great progress in both theoretical and experimental aspects,but with no publications on the joint research from theoretical analyses,experimental measurements,and numerical validations.Several key issues challenge the joint research with comparisons of experimental and numerical results,such as digital imaging of heterogeneous poroelastic properties,estimation of acoustoelastic constants,numerical dispersion at high frequencies and strong heterogeneities,elastic nonlinearity due to compliant pores,and contamination by boundary reflections.Conventional poroacoustoelastic theory,valid for the linear elastic deformation of rock grains and stiff pores,is modified by incorporating a dualporosity model to account for elastic nonlinearity due to compliant pores subject to high-magnitude loading stresses.A modified finite-element method is employed to simulate the subtle effect of microstructures on wave propagation in prestressed digital cores.We measure the heterogeneity of samples by extracting the autocorrelation length of digital cores for a rough estimation of scattering intensity.We conductexperimental measurements with a fluid-saturated sandstone sample under a constant confining pressure of 65 MPa and increasing pore pressures from 5 to 60 MPa.Numerical simulations for ultrasound propagation in the prestressed fluid-saturated digital core of the sample are followed based on the proposed poro-acoustoelastic model with compliant pores.The results demonstrate a general agreement between experimental and numerical waveforms for different stresses,validating the performance of the presented modeling scheme.The excellent agreement between experimental and numerical coda quality factors demonstrates the applicability for the numerical investigation of the stress-associated scattering attenuation in prestressed porous rocks. 展开更多
关键词 Poro-acoustoelasticity with compliant pores Elastic waves Prestressed porous rocks Numerical modeling Stressinduced scattering attenuation
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A new seismic daylight imaging method for determining the structure of lithospheric discontinuity 被引量:1
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作者 weijia sun Liyun FU +1 位作者 Wei WEI Qingya TANG 《Science China Earth Sciences》 SCIE EI CAS CSCD 2019年第2期473-488,共16页
The fine-scale structures of lithosphere discontinuities contain important information on the dynamics of lithosphere formation, development, transformation, and destruction. In this paper, a new seismic daylight imag... The fine-scale structures of lithosphere discontinuities contain important information on the dynamics of lithosphere formation, development, transformation, and destruction. In this paper, a new seismic daylight imaging method is developed to explore the small-scale structures of lithosphere discontinuities. This method makes use of the P-wave first arrival and coda in the 0.5–4 Hz high frequency band of teleseismic events, and reaches a resolution of 2 km for lithosphere discontinuities. This method rests on the basic principle that the autocorrelation of the vertically incident transmission response below the seismic station is equivalent to the reflection response with the source and station both on the free surface. The transmission responses include the first-arrival P-waves below the station traversing the discontinuities to reach the free surface, and the multiple reflections between the free surface and the discontinuities. In this study, the normal incidence requirement of the method is further extended to include dip incidence illumination, which expands its applicability. The accuracy and feasibility of the seismic daylight imaging (SDI) theory are verified by synthesized theoretical seismograms, and the factors affecting the imaging results are discussed. The data processing steps and the interpretation criteria for the method are also given. The fine-scale lithosphere structure of two permanent stations at the eastern North China Craton is determined by the method described here, as well as instantaneous frequency. Clear discontinuities are found in the lithospheric mantle at 52 and 75 km below the two stations, respectively. Seismic daylight imaging and the receiver function reveal a more consistent lithosphere structure beneath the MBWA permanent station of the West Australia Craton, with the unmistakable presence of the lithosphere discontinuities.High-frequency SDI can be used to detect the fine-scale lithospheric structures. As its waveform is more complex, and hence appropriate reference to existing seismological information, such as from tomographic velocity inversion and the receiver function, is recommended. 展开更多
关键词 LITHOSPHERE DISCONTINUITY Mid-lithosphere DISCONTINUITY SEISMIC DAYLIGHT imaging AUTOCORRELATION
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A Stable Q Compensated Reverse Time Migration Method Based on Excitation Amplitude Imaging Condition 被引量:1
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作者 Qingqing Li Li-Yun Fu +2 位作者 weijia sun Wei Wei Wanting Hou 《Communications in Computational Physics》 SCIE 2020年第6期141-166,共26页
The stability and efficiency,especially the stability,are generally concerned issues in Q compensated reverse time migration(Q-RTM).The instability occurs because of the exponentially boosted high frequency ambient no... The stability and efficiency,especially the stability,are generally concerned issues in Q compensated reverse time migration(Q-RTM).The instability occurs because of the exponentially boosted high frequency ambient noise during the forward or backward seismic wavefield propagation.The regularization and low-pass filtering methods are two effective strategies to control the instability of the wave propagation in Q-RTM.However,the regularization parameters are determined experimentally,and the wavefield cannot be recovered accurately.The low-pass filtering method cannot balance the selection of cutoff frequency for varying Q values,and may damage the effective signals,especially when the signal-to-noise ratio(SNR)of the seismic data is low,the Q-RTM will be a highly unstable process.In order to achieve the purpose of stability,the selection of cutoff frequency will be small enough,which can cause great damage to the effective high frequency signals.In this paper,we present a sta-ble Q-RTM algorithm based on the excitation amplitude imaging condition,which can compensate both the amplitude attenuation and phase dispersion.Unlike the existing Q-RTM algorithms enlarging the amplitude,the exponentially attenuated seismic wavefield will be used during both the forward and backward wavefield propagation of Q-RTM.Therefore,the new Q-RTM algorithm is relative stable,even for the low SNR seismic data.In order to show the accuracy and stability of our stable Q-RTM algorithm clearly,an example based on Graben model will be illustrated.Then,a realistic BP gas chimney model further demonstrates that the proposed method enjoys good stability and anti-noise performance compared with the traditional Q-RTM with amplitude amplification.Compare the Q-RTM images of these two models to the reference images obtained by the acoustic RTM with acoustic seismic data,the new Q-RTM results match the reference images quite well.The proposed method is also tested using a field seismic data,the result shows the effectiveness of our proposed method. 展开更多
关键词 STABLE reverse time migration ATTENUATION
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Study of MRPC technology for BESIII endcap-TOF upgrade
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作者 Xin Li Yongjie sun +18 位作者 Cheng Li Zhen Liu Yuekun Heng Ming Shao Xiaozhuang Wang Zhi Wu Ping Cao Mingming Chen Hongliang Dai Shubing Liu Xiaolan Luo Xiaoshan Jiang Shengsen sun Zebo Tang weijia sun Siyu Wang Meihang Xu Rongxing Yang Kejun Zhu 《Radiation Detection Technology and Methods》 2017年第2期31-36,共6页
Purpose In order to improve the charged particle identi-fication capability,end-cap time-of-flight(ETOF)detector of the Beijing Spectrometer(BESIII)has been upgraded with multi-gap resistive plate chamber(MRPC)technol... Purpose In order to improve the charged particle identi-fication capability,end-cap time-of-flight(ETOF)detector of the Beijing Spectrometer(BESIII)has been upgraded with multi-gap resistive plate chamber(MRPC)technology,aiming at an overall time resolution of 80 ps for minimum-ionization particles to extend the K/πseparation(2σ)momentum range to 1.4 GeV/c.Methods The previous version of ETOF in BESIII consisted of plastic scintillators.The multi-hit events distort both shape and amplitude of the output signals.MRPC technique was chosen for the BESIII ETOF upgrade as it provides high time resolution and high detection efficiency,is of relatively low cost and is insensitive to neutral particles.Most importantly,the fine segmentation of the MRPC readout stripes can suppress multi-hit events effectively.Results The final design of MRPC module for ETOF is characterized by double-stack(2×6)structure,dual-end readout mode and precision electronics.To batch-produce and test these MRPC modules,a series of tools and production procedures as well as related performance simulation and test methods were developed.Results showed that each MRPC module’s intrinsic time resolution(including the electronics contribution)is around 50 ps and the efficiency is better than 97%.The overall performance of the upgraded ETOF is better than the designed index.The new ETOF has been successfully installed at BESIII and run in 2016. 展开更多
关键词 Multi-gap resistive plate chamber Endcap time-of-flight detector Particle identification Beijing spectrometer High time resolution
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