Current exploration needs are satisfied by multisource technology,which offers low cost,high efficiency,and high precision.The delay time,which determines the separation effects of the multisource blended data,is one ...Current exploration needs are satisfied by multisource technology,which offers low cost,high efficiency,and high precision.The delay time,which determines the separation effects of the multisource blended data,is one of the most crucial parameters in the acquisition and separation of multisource data.This study uses the deblending method of multisource data based on a periodically varying cosine code and analyses the effects of the two parameters,namely,the period amplitude and period length,used in this method on the separation of the multisource blended data.Meanwhile,the obtained coherence data is used to prove the correlation between the separation of multisource data and the two parameters.Examples of synthetic and field data are adopted to demonstrate that from a qualitative perspective,increasing the amplitude of the periodic code improves the separation effect within a reasonable delay time range.When the period length varies in a suitable range,the secondary noise becomes relatively incoherent,resulting in the separation result with a higher signal-to-noise ratio(SNR).From a quantitative perspective,the significant values(Sig.)of the period amplitude and length on the SNRs are less than 0.05,verifying the correlation between the separation of multisource data and the two parameters.展开更多
The problem of collinear periodic cracks in an infinite piezoelectric body is studied. Effect of saturation strips at the crack-tips is taken into account. By means of the Stroh formalism and the conformal mapping tec...The problem of collinear periodic cracks in an infinite piezoelectric body is studied. Effect of saturation strips at the crack-tips is taken into account. By means of the Stroh formalism and the conformal mapping technique, the general periodic solutions for collinear cracks are obtained. The stress intensity factors and the size of saturation strips are derived analytically, and their dependencies on the ratio of the periodicity on the half-length of the crack are analyzed in detail. Numerical results show the following two facts. (1) When h/l 〉 4.0, the stress intensity factors become almost identical to those of a single crack in an infinite piezoelectric body. This indicates that the interaction between cracks can be ignored in establishing the criterion for the crack initiation in this case. (2) The speed of the saturation strip size of periodic cracks approaching that of a single crack depends on the electric load applied at infinity. In general, a large electric load at infinity is associated with a slow approaching speed.展开更多
Scientists pay great attention to different-time-scale signals in the lengllh of day (LOD) variations △LOD, which provide signatures of the Earth's interior structure, couplings among different layers, and potenti...Scientists pay great attention to different-time-scale signals in the lengllh of day (LOD) variations △LOD, which provide signatures of the Earth's interior structure, couplings among different layers, and potential excitations of ocean and atmosphere. In this study, based on the ensemble empirical mode decomposition (EEMD), we analyzed the latest time series of △LOD data spanning from January 1962 to March 2015. We observed the signals with periods and amplitudes of about 0.5 month and 0.19 ms, 1.0 month and 0.19 ms, 0.5 yr and 0.22 ms, 1.0 yr and 0.18 ms, 2.28 yr and 0.03 ms, 5.48 yr and 0.05 ms, respectively, in coincidence with the results of predecessors. In addition, some signals that were previously not definitely observed by predecessors were detected in this study, with periods and amplitudes of 9.13 d and 0.12 ms, 13.69 yr and 0.10 ms, respectively. The mechanisms of the LOD fluctuations of these two signals are still open.展开更多
Considering the mechnoelectrical coupling, the localization of SH-waves in disordered periodic layered piezoelectric structures is studied. The waves propagating in directions normal and tangential to the layers are c...Considering the mechnoelectrical coupling, the localization of SH-waves in disordered periodic layered piezoelectric structures is studied. The waves propagating in directions normal and tangential to the layers are considered. The transfer matrices between two consecutive unit cells are obtained according to the continuity conditions. The expressions of localization factor and localization length in the disordered periodic structures are presented. For the disordered periodic piezoelectric structures, the numerical results of localization factor and localization length are presented and discussed. It can be seen from the results that the frequency passbands and stopbands appear for the ordered periodic structures and the wave localization phenomenon occurs in the disordered periodic ones, and the larger the coefficient of variation is, the greater the degree of wave localization is. The widths of stopbands in the ordered periodic structures are very narrow when the properties of the consecutive piezoelectric materials are similar and the intervals of stopbands become broader when a certain material parameter has large changes. For the wave propagating in the direction normal to the layers the localization length has less dependence on the frequency, but for the wave propagating in the direction tangential to the layers the localization length is strongly dependent on the frequency.展开更多
作物生殖生长期长度与作物产量和品质密切相关。为深入探究作物生殖生长期长度(reproductive growth period lengths,RGLs)对气候变化和技术进步的响应,基于1981—2010年长江中下游地区单季稻生殖生长期和气象数据,量化不同RGLs (孕穗...作物生殖生长期长度与作物产量和品质密切相关。为深入探究作物生殖生长期长度(reproductive growth period lengths,RGLs)对气候变化和技术进步的响应,基于1981—2010年长江中下游地区单季稻生殖生长期和气象数据,量化不同RGLs (孕穗期—抽穗期(booting to heading,BDHD)、抽穗期—乳熟期(heading to milking,HDMS)、乳熟期—成熟期(milking to maturity,MSMD)和孕穗期—成熟期(booting to maturity,BDMD))对平均温度(mean temperature,TEM)、累积降水量(cumulative precipitation,PRE)和累积日照时数(cumulative sunshine duration,SSD)的敏感性,并分离气候变化和技术进步对不同RGLs的影响。结果表明,1981—2010年长江中下游地区单季稻BDMD呈延长趋势(0.24d a^(–1)),其中,HDMS延长趋势最明显(0.16 d a^(–1))。气候因子中高温和寡照不利于单季稻不同RGLs延长,其中,TEM对BDHD、HDMS和MSMD变化趋势的平均相对贡献分别为–50.0%、–50.7%和–21.9%,SSD对BDHD、HDMS和MSMD变化趋势的平均相对贡献分别为–47.2%、–48.7%和–67.6%。技术进步弥补了气候变化对不同RGLs变化趋势的不利影响。研究表明,技术进步可能是当前单季稻稳产高产和趋利避害的主要手段,未来可以采用较长生殖生长期和耐热性品种来适应持续的气候变化。展开更多
In this paper a group of long period seismic waves in Shanghai area induced by Taiwan large earthquake is presented by using the method of semi empirical Green function, the period is up to 20 s. Such seismic waves c...In this paper a group of long period seismic waves in Shanghai area induced by Taiwan large earthquake is presented by using the method of semi empirical Green function, the period is up to 20 s. Such seismic waves can be used as a reference curve to test the strength of long period structures and their aseismic design. The long period part of seismic influence curve presented in 'Architecture Aseismic Design Code'(GBJ11 89) is less than 3 s, and uncertainties exist in the effects of earthquake safety evaluation. This research will be able to eliminate these shortages.展开更多
全球气候变化直接影响作物生产。玉米是中国种植面积最大的粮食作物,系统探究未来气候变化对其生产力的影响对保障玉米高产稳产和粮食安全具有重要意义。为探究未来气候变化对中国玉米生产力影响,该研究基于SSP1-2.6和SSP5-8.5共2种气...全球气候变化直接影响作物生产。玉米是中国种植面积最大的粮食作物,系统探究未来气候变化对其生产力的影响对保障玉米高产稳产和粮食安全具有重要意义。为探究未来气候变化对中国玉米生产力影响,该研究基于SSP1-2.6和SSP5-8.5共2种气候情景(shared socioeconomic pathways,SSP)1981—2100年逐日气象资料以及中国气象局农业气象观测站玉米生育期数据和土壤数据,使用调参验证后的农业生产系统模拟模型(agricultural production systems simulator,APSIM-Maize)解析了气候变化对中国玉米主产区高产性和稳产性的影响。结果表明:(1)未来气候情景下,中国玉米主产区生育期内气温和≥10℃有效积温总体呈增加趋势,SSP5-8.5气候情景下升温幅度高于SSP1-2.6气候情景;降水量年际波动大,变化趋势不显著;太阳总辐射呈先增加后减少趋势。(2)若不采取适应措施,未来气候变化使玉米全生育期、营养生长期和生殖生长期总体呈缩短趋势,且SSP5-8.5情景下缩短幅度大于SSP1-2.6情景,2080 s缩短幅度大于2030 s和2050 s。(3)无适应措施条件下,未来气候变化下研究区域玉米光温潜在产量和雨养潜在产量总体呈下降趋势,SSP5-8.5情景下较SSP1-2.6情景下减产效应更大,2个情景光温潜在产量减产率平均值分别为13.8%和11.9%,雨养潜在产量减产率平均值分别为17.5%和14.0%。玉米潜在产量的稳定性略有提高,但区域间存在差异。因此,未来气候变化使中国玉米生产力总体下降,稳定性略有提高。研究为未来玉米高产稳产和中国玉米种植区划提供理论依据。展开更多
利用IERS(International Earth Rotation and Reference Systems Service)发布的EOP 14 C04产品中1984~2022年LOD实测值进行频谱分析及周期项提取,并采用最小二乘外推模型联合多项式曲线拟合模型方法将提取到的周期项应用于对LOD序列的...利用IERS(International Earth Rotation and Reference Systems Service)发布的EOP 14 C04产品中1984~2022年LOD实测值进行频谱分析及周期项提取,并采用最小二乘外推模型联合多项式曲线拟合模型方法将提取到的周期项应用于对LOD序列的拟合。实验结果表明,相比于单一的LS外推模型拟合,新方法拟合序列的RMSE从0.0003 s下降至0.0001 s,且新方法将确定系数从0.80提高到0.97左右。该研究结果可为LOD序列的预报研究提供参考。展开更多
<strong>Background:</strong><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"> Preterm prelabor ruptur...<strong>Background:</strong><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"> Preterm prelabor rupture of membranes (PPROM) is a major cause of Pretem Birth (PTB), Pretem Birth (PTB) is the most significant cause of perinatal morbidity and mortality worldwide. Cervical length (CL), posterior uterocervical angle (PUCA) and anterior uterocervical angle (AUCA) have been postulated in several studies to have an important role in prediction of PTB. Up to our knowledge, this is the first study that combines the three cervical parameters in prediction of latency period in women with PPROM. </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><b><span style="font-family:Verdana;">Aim</span></b></span></span><span><span><span style="font-family:""> <b><span style="font-family:Verdana;">of</span></b> <b><span style="font-family:Verdana;">the</span></b> <b><span style="font-family:Verdana;">Work:</span></b> </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">To assess the accuracy of cervical length, posterior uterocervical angle and anterior uterocervical angle in prediction of latency period in women with Preterm prelabor rupture of membranes. </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><b><span style="font-family:Verdana;">Subjects</span></b></span></span><span><span><span style="font-family:""> <b><span style="font-family:Verdana;">and</span></b> <b><span style="font-family:Verdana;">Methods:</span></b><span style="font-family:Verdana;"> A </span></span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">Prospective cohort study</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"> on </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">205 women with PPROM </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">was held </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">at Ain Shams University Maternity Hospital</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">,</span></span></span><span><span><span style="font-family:""><span style="font-family:Verdana;"> a transvaginal ultrasound was performed to measure cervical length, posterior uterocervical angle, anterior uterocervical angle. </span><b><span style="font-family:Verdana;">Results:</span></b><span style="font-family:Verdana;"> A total of 205 pregnant women with PPROM were included in this study, the latency grade was within 2 days in 57 (27.8%) of cases while was after 2 days in 148 (72.2%) of cases. As regards cervical length cut-off value 25.0 mm, sensitivity was 78.9%, specificity was 65.5%, posterior uterocervical angle cut-off value 108.0<span style="white-space:nowrap;">°</span>, sensitivity was 93.0%, specificity was 60.1%, and anterior uterocervical angle cut-off value 106.0<span style="white-space:nowrap;">°</span>, sensitivity was 93.0%, specificity was 71.6%. </span></span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><b><span style="font-family:Verdana;">Conclusion:</span></b></span></span><span><span><span style="font-family:""> </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">The combination of cervical length (CL), posterior uterocervical angle (PUCA) and anterior uterocervical angle (AUCA) measurements greatly predict</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">s</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"> the latency period in women with PPROM, and Anterior </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">uterocervical angle (AUCA) ≥ 106.0<span style="white-space:nowrap;">°</span></span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"> had </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">the </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">highest diagnostic value</span></span></span><span><span><span style="font-family:""> </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">in predicting latency period within two days.</span></span></span>展开更多
基金The project supported by Natioual Natural Science Foundation of China under Grant Nos. 1057508 and 10302018 and the Natural Science Foundation of Zhejiang Province of China under Grant No. Y605056The authors would like to thank Prof. Sen-Yue Lou for helpful discussions.
基金supported by the National Key Research and Development Program of China(2018YFA0702503)the National Natural Science Foundation of China(41674122).
文摘Current exploration needs are satisfied by multisource technology,which offers low cost,high efficiency,and high precision.The delay time,which determines the separation effects of the multisource blended data,is one of the most crucial parameters in the acquisition and separation of multisource data.This study uses the deblending method of multisource data based on a periodically varying cosine code and analyses the effects of the two parameters,namely,the period amplitude and period length,used in this method on the separation of the multisource blended data.Meanwhile,the obtained coherence data is used to prove the correlation between the separation of multisource data and the two parameters.Examples of synthetic and field data are adopted to demonstrate that from a qualitative perspective,increasing the amplitude of the periodic code improves the separation effect within a reasonable delay time range.When the period length varies in a suitable range,the secondary noise becomes relatively incoherent,resulting in the separation result with a higher signal-to-noise ratio(SNR).From a quantitative perspective,the significant values(Sig.)of the period amplitude and length on the SNRs are less than 0.05,verifying the correlation between the separation of multisource data and the two parameters.
基金Project supported by the Postdoctoral Science Foundation of China (No.20070410944)
文摘The problem of collinear periodic cracks in an infinite piezoelectric body is studied. Effect of saturation strips at the crack-tips is taken into account. By means of the Stroh formalism and the conformal mapping technique, the general periodic solutions for collinear cracks are obtained. The stress intensity factors and the size of saturation strips are derived analytically, and their dependencies on the ratio of the periodicity on the half-length of the crack are analyzed in detail. Numerical results show the following two facts. (1) When h/l 〉 4.0, the stress intensity factors become almost identical to those of a single crack in an infinite piezoelectric body. This indicates that the interaction between cracks can be ignored in establishing the criterion for the crack initiation in this case. (2) The speed of the saturation strip size of periodic cracks approaching that of a single crack depends on the electric load applied at infinity. In general, a large electric load at infinity is associated with a slow approaching speed.
基金supported by National 973 Project China (2013CB733305)National Natural Science Foundation of China (NSFCs) (41174011,41429401,41210006,41128003,41021061)
文摘Scientists pay great attention to different-time-scale signals in the lengllh of day (LOD) variations △LOD, which provide signatures of the Earth's interior structure, couplings among different layers, and potential excitations of ocean and atmosphere. In this study, based on the ensemble empirical mode decomposition (EEMD), we analyzed the latest time series of △LOD data spanning from January 1962 to March 2015. We observed the signals with periods and amplitudes of about 0.5 month and 0.19 ms, 1.0 month and 0.19 ms, 0.5 yr and 0.22 ms, 1.0 yr and 0.18 ms, 2.28 yr and 0.03 ms, 5.48 yr and 0.05 ms, respectively, in coincidence with the results of predecessors. In addition, some signals that were previously not definitely observed by predecessors were detected in this study, with periods and amplitudes of 9.13 d and 0.12 ms, 13.69 yr and 0.10 ms, respectively. The mechanisms of the LOD fluctuations of these two signals are still open.
基金The project supported by National Natural Science Foundation of China (10632020, 10672017 and 20451057)
文摘Considering the mechnoelectrical coupling, the localization of SH-waves in disordered periodic layered piezoelectric structures is studied. The waves propagating in directions normal and tangential to the layers are considered. The transfer matrices between two consecutive unit cells are obtained according to the continuity conditions. The expressions of localization factor and localization length in the disordered periodic structures are presented. For the disordered periodic piezoelectric structures, the numerical results of localization factor and localization length are presented and discussed. It can be seen from the results that the frequency passbands and stopbands appear for the ordered periodic structures and the wave localization phenomenon occurs in the disordered periodic ones, and the larger the coefficient of variation is, the greater the degree of wave localization is. The widths of stopbands in the ordered periodic structures are very narrow when the properties of the consecutive piezoelectric materials are similar and the intervals of stopbands become broader when a certain material parameter has large changes. For the wave propagating in the direction normal to the layers the localization length has less dependence on the frequency, but for the wave propagating in the direction tangential to the layers the localization length is strongly dependent on the frequency.
文摘作物生殖生长期长度与作物产量和品质密切相关。为深入探究作物生殖生长期长度(reproductive growth period lengths,RGLs)对气候变化和技术进步的响应,基于1981—2010年长江中下游地区单季稻生殖生长期和气象数据,量化不同RGLs (孕穗期—抽穗期(booting to heading,BDHD)、抽穗期—乳熟期(heading to milking,HDMS)、乳熟期—成熟期(milking to maturity,MSMD)和孕穗期—成熟期(booting to maturity,BDMD))对平均温度(mean temperature,TEM)、累积降水量(cumulative precipitation,PRE)和累积日照时数(cumulative sunshine duration,SSD)的敏感性,并分离气候变化和技术进步对不同RGLs的影响。结果表明,1981—2010年长江中下游地区单季稻BDMD呈延长趋势(0.24d a^(–1)),其中,HDMS延长趋势最明显(0.16 d a^(–1))。气候因子中高温和寡照不利于单季稻不同RGLs延长,其中,TEM对BDHD、HDMS和MSMD变化趋势的平均相对贡献分别为–50.0%、–50.7%和–21.9%,SSD对BDHD、HDMS和MSMD变化趋势的平均相对贡献分别为–47.2%、–48.7%和–67.6%。技术进步弥补了气候变化对不同RGLs变化趋势的不利影响。研究表明,技术进步可能是当前单季稻稳产高产和趋利避害的主要手段,未来可以采用较长生殖生长期和耐热性品种来适应持续的气候变化。
文摘In this paper a group of long period seismic waves in Shanghai area induced by Taiwan large earthquake is presented by using the method of semi empirical Green function, the period is up to 20 s. Such seismic waves can be used as a reference curve to test the strength of long period structures and their aseismic design. The long period part of seismic influence curve presented in 'Architecture Aseismic Design Code'(GBJ11 89) is less than 3 s, and uncertainties exist in the effects of earthquake safety evaluation. This research will be able to eliminate these shortages.
文摘全球气候变化直接影响作物生产。玉米是中国种植面积最大的粮食作物,系统探究未来气候变化对其生产力的影响对保障玉米高产稳产和粮食安全具有重要意义。为探究未来气候变化对中国玉米生产力影响,该研究基于SSP1-2.6和SSP5-8.5共2种气候情景(shared socioeconomic pathways,SSP)1981—2100年逐日气象资料以及中国气象局农业气象观测站玉米生育期数据和土壤数据,使用调参验证后的农业生产系统模拟模型(agricultural production systems simulator,APSIM-Maize)解析了气候变化对中国玉米主产区高产性和稳产性的影响。结果表明:(1)未来气候情景下,中国玉米主产区生育期内气温和≥10℃有效积温总体呈增加趋势,SSP5-8.5气候情景下升温幅度高于SSP1-2.6气候情景;降水量年际波动大,变化趋势不显著;太阳总辐射呈先增加后减少趋势。(2)若不采取适应措施,未来气候变化使玉米全生育期、营养生长期和生殖生长期总体呈缩短趋势,且SSP5-8.5情景下缩短幅度大于SSP1-2.6情景,2080 s缩短幅度大于2030 s和2050 s。(3)无适应措施条件下,未来气候变化下研究区域玉米光温潜在产量和雨养潜在产量总体呈下降趋势,SSP5-8.5情景下较SSP1-2.6情景下减产效应更大,2个情景光温潜在产量减产率平均值分别为13.8%和11.9%,雨养潜在产量减产率平均值分别为17.5%和14.0%。玉米潜在产量的稳定性略有提高,但区域间存在差异。因此,未来气候变化使中国玉米生产力总体下降,稳定性略有提高。研究为未来玉米高产稳产和中国玉米种植区划提供理论依据。
文摘<strong>Background:</strong><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"> Preterm prelabor rupture of membranes (PPROM) is a major cause of Pretem Birth (PTB), Pretem Birth (PTB) is the most significant cause of perinatal morbidity and mortality worldwide. Cervical length (CL), posterior uterocervical angle (PUCA) and anterior uterocervical angle (AUCA) have been postulated in several studies to have an important role in prediction of PTB. Up to our knowledge, this is the first study that combines the three cervical parameters in prediction of latency period in women with PPROM. </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><b><span style="font-family:Verdana;">Aim</span></b></span></span><span><span><span style="font-family:""> <b><span style="font-family:Verdana;">of</span></b> <b><span style="font-family:Verdana;">the</span></b> <b><span style="font-family:Verdana;">Work:</span></b> </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">To assess the accuracy of cervical length, posterior uterocervical angle and anterior uterocervical angle in prediction of latency period in women with Preterm prelabor rupture of membranes. </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><b><span style="font-family:Verdana;">Subjects</span></b></span></span><span><span><span style="font-family:""> <b><span style="font-family:Verdana;">and</span></b> <b><span style="font-family:Verdana;">Methods:</span></b><span style="font-family:Verdana;"> A </span></span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">Prospective cohort study</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"> on </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">205 women with PPROM </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">was held </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">at Ain Shams University Maternity Hospital</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">,</span></span></span><span><span><span style="font-family:""><span style="font-family:Verdana;"> a transvaginal ultrasound was performed to measure cervical length, posterior uterocervical angle, anterior uterocervical angle. </span><b><span style="font-family:Verdana;">Results:</span></b><span style="font-family:Verdana;"> A total of 205 pregnant women with PPROM were included in this study, the latency grade was within 2 days in 57 (27.8%) of cases while was after 2 days in 148 (72.2%) of cases. As regards cervical length cut-off value 25.0 mm, sensitivity was 78.9%, specificity was 65.5%, posterior uterocervical angle cut-off value 108.0<span style="white-space:nowrap;">°</span>, sensitivity was 93.0%, specificity was 60.1%, and anterior uterocervical angle cut-off value 106.0<span style="white-space:nowrap;">°</span>, sensitivity was 93.0%, specificity was 71.6%. </span></span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><b><span style="font-family:Verdana;">Conclusion:</span></b></span></span><span><span><span style="font-family:""> </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">The combination of cervical length (CL), posterior uterocervical angle (PUCA) and anterior uterocervical angle (AUCA) measurements greatly predict</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">s</span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"> the latency period in women with PPROM, and Anterior </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">uterocervical angle (AUCA) ≥ 106.0<span style="white-space:nowrap;">°</span></span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;"> had </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">the </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">highest diagnostic value</span></span></span><span><span><span style="font-family:""> </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">in predicting latency period within two days.</span></span></span>