Oil and gas seismic exploration have to adopt irregular seismic acquisition due to the increasingly complex exploration conditions to adapt to complex geological conditions and environments.However,the irregular seism...Oil and gas seismic exploration have to adopt irregular seismic acquisition due to the increasingly complex exploration conditions to adapt to complex geological conditions and environments.However,the irregular seismic acquisition is accompanied by the lack of acquisition data,which requires high-precision regularization.The sparse signal feature in the transform domain in compressed sensing theory is used in this paper to recover the missing signal,involving sparse transform base optimization and threshold modeling.First,this paper analyzes and compares the effects of six sparse transformation bases on the reconstruction accuracy and efficiency of irregular seismic data and establishes the quantitative relationship between sparse transformation and reconstruction accuracy and efficiency.Second,an adaptive threshold modeling method based on sparse coefficient is provided to improve the reconstruction accuracy.Test results show that the method has good adaptability to different seismic data and sparse transform bases.The f-x domain reconstruction method of effective frequency samples is studied to address the problem of low computational efficiency.The parallel computing strategy of curvelet transform combined with OpenMP is further proposed,which substantially improves the computational efficiency under the premise of ensuring the reconstruction accuracy.Finally,the actual acquisition data are used to verify the proposed method.The results indicate that the proposed method strategy can solve the regularization problem of irregular seismic data in production and improve the imaging quality of the target layer economically and efficiently.展开更多
目的系统评价脑白质疏松在卒中复发风险预测中的价值。方法计算机检索PubMed、Web of science、Embase及维普、中国生物医学文献数据库、中国知网等数据库截止2019年3月15日收录的关于脑白质疏松及卒中复发关系的文献。提取资料进行质...目的系统评价脑白质疏松在卒中复发风险预测中的价值。方法计算机检索PubMed、Web of science、Embase及维普、中国生物医学文献数据库、中国知网等数据库截止2019年3月15日收录的关于脑白质疏松及卒中复发关系的文献。提取资料进行质量评价并进行meta分析,利用Begg's漏斗图和Egger's检验评估发表偏倚。结果最终纳入33篇文献,共34444例。meta分析显示,当结局指标为任何类型复发性卒中时,中重度组与轻度或无组比较(RR=1.71,95%CI:1.44~2.04),I2=55.69%;有脑白质疏松组与无脑白质疏松组比较(RR=1.79,95%CI:1.43~2.25),I2=56.26%;连续性分析组(RR=1.81,95%CI:1.47~2.23),I2=34.63%。当结局指标为缺血性卒中时,中重度组与轻度或无脑白质疏松组比较(RR=1.82,95%CI:1.36~2.42),I2=48.43%;有脑白质疏松组与无脑白质疏松组比较(RR=2.13,95%CI:1.37~3.32),I2=70.64%;连续性分析组(RR=2.01,95%CI:1.13~3.58),I2=69.78%。亚组分析结果显示脑白质疏松对于远期复发性卒中的预测价值更高。通过Begg's漏斗图和Egger's检验,仅当结局指标为任何类型复发性卒中时,中重度组与轻度或无脑白质疏松组比较有显著性发表偏倚,经剪补法校正后仍提示相关性。结论脑白质疏松对于复发性卒中具有预测价值。展开更多
基金supported by the National Science and Technology Major project(No.2016ZX05024001003)the Innovation Consortium Project of China Petroleum,and the Southwest Petroleum University(No.2020CX010201).
文摘Oil and gas seismic exploration have to adopt irregular seismic acquisition due to the increasingly complex exploration conditions to adapt to complex geological conditions and environments.However,the irregular seismic acquisition is accompanied by the lack of acquisition data,which requires high-precision regularization.The sparse signal feature in the transform domain in compressed sensing theory is used in this paper to recover the missing signal,involving sparse transform base optimization and threshold modeling.First,this paper analyzes and compares the effects of six sparse transformation bases on the reconstruction accuracy and efficiency of irregular seismic data and establishes the quantitative relationship between sparse transformation and reconstruction accuracy and efficiency.Second,an adaptive threshold modeling method based on sparse coefficient is provided to improve the reconstruction accuracy.Test results show that the method has good adaptability to different seismic data and sparse transform bases.The f-x domain reconstruction method of effective frequency samples is studied to address the problem of low computational efficiency.The parallel computing strategy of curvelet transform combined with OpenMP is further proposed,which substantially improves the computational efficiency under the premise of ensuring the reconstruction accuracy.Finally,the actual acquisition data are used to verify the proposed method.The results indicate that the proposed method strategy can solve the regularization problem of irregular seismic data in production and improve the imaging quality of the target layer economically and efficiently.
文摘目的系统评价脑白质疏松在卒中复发风险预测中的价值。方法计算机检索PubMed、Web of science、Embase及维普、中国生物医学文献数据库、中国知网等数据库截止2019年3月15日收录的关于脑白质疏松及卒中复发关系的文献。提取资料进行质量评价并进行meta分析,利用Begg's漏斗图和Egger's检验评估发表偏倚。结果最终纳入33篇文献,共34444例。meta分析显示,当结局指标为任何类型复发性卒中时,中重度组与轻度或无组比较(RR=1.71,95%CI:1.44~2.04),I2=55.69%;有脑白质疏松组与无脑白质疏松组比较(RR=1.79,95%CI:1.43~2.25),I2=56.26%;连续性分析组(RR=1.81,95%CI:1.47~2.23),I2=34.63%。当结局指标为缺血性卒中时,中重度组与轻度或无脑白质疏松组比较(RR=1.82,95%CI:1.36~2.42),I2=48.43%;有脑白质疏松组与无脑白质疏松组比较(RR=2.13,95%CI:1.37~3.32),I2=70.64%;连续性分析组(RR=2.01,95%CI:1.13~3.58),I2=69.78%。亚组分析结果显示脑白质疏松对于远期复发性卒中的预测价值更高。通过Begg's漏斗图和Egger's检验,仅当结局指标为任何类型复发性卒中时,中重度组与轻度或无脑白质疏松组比较有显著性发表偏倚,经剪补法校正后仍提示相关性。结论脑白质疏松对于复发性卒中具有预测价值。
