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维普期刊数据库博看期刊

Joint asymptotic distribution of exceedances point process and partial sum of stationary Gaussian sequence

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Applied Mathematics(A Journal of Chinese Universities) 2011年第3期26卷 319-326页

作者： TAN Zhong-quan peng zuo-xiang Department of Mathematics Zunyi Normal College Zunyi 563002 China Department of Mathematics Soochow University Suzhou 215006 China School of Mathematics and Statistics Southwest University Chongqing 400715 China

Let {Xi}i=1^∞ be a standardized stationary Gaussian sequence with covariance function τ（n） =EX1Xn＋1, Sn =∑i=1^nXi,and X^-n=Sn/*** let Nn be the point process formed by the exceedances of random level （x/√2 log n＋√2 log n-log（4π log n）/2√log n） √1-τ（n）＋ X^-n by X1,X2,…, Xn. Under some mild conditions, Nn and Sn are asymptotically independent, and Nn converges weakly to a Poisson process on （0,1].

关键词： stationary Gaussian sequence exceedances point process partial sum.

Almost sure limit theorem for the maximum of a class of quasi-stationary sequences

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Applied Mathematics(A Journal of Chinese Universities) 2014年第1期29卷 44-52页

作者： ZHUANG Guang-ming peng zuo-xiang School of Mathematical Sciences Liaocheng University School of Automation Nanjing University of Science and Technology School of Mathematics and Statistics Southwest University

This paper investigates the problem of almost sure limit theorem for the maximum of quasi-stationary sequence based on the result of Turkman and Walker. We prove an almost sure limit theorem for the maximum of a class of quasi-stationary sequence under weak dependence conditions of D （uk, un） and αtm,ln = 0 （（log log n）-（1＋ε））.

关键词： quasi-stationary sequence maximum limit distribution almost sure central limit theorem

Limit theorems for supremum of Gaussian processes over a random interval

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Applied Mathematics(A Journal of Chinese Universities) 2018年第3期33卷 335-343页

作者： LIN Fu-ming peng zuo-xiang School of Statistics and Management Shanghai University of Finance and Economics School of Mathematics and Statistics Sichuan University of Science & Engineering School of Mathematics and Statistics Southwestern University

Let {X(t), t ≥ 0} be a centered stationary Gaussian process with correlation r(t)such that 1-r(t) is asymptotic to a regularly varying function. With T being a nonnegative random variable and independent of X(t), the... 详细信息

关键词： stationary Gaussian process supremum of a process regularly varying functions random intervals

Effects of mechanical strain amplitude on the isothermal fatigue behavior of H13

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International Journal of Minerals,Metallurgy and Materials 2017年第9期24卷 1004-1009页

作者： Yan Zeng peng-peng zuo Xiao-chun Wu Shu-wen Xia School of Materials Science and Engineering Shanghai UniversityShanghai 200072China

Isothermal fatigue (IF) tests were performed on H13 tool steel subjected to three different mechanical strain amplitudes at a constant temperature to determine the effects of mechanical strain amplitude on the microstructure of the steel samples. The samples' extent of damage after IF tests was compared by observation of their cracks and calculation of their damage parameters. Optical microscopy (OM) and scanning electron microscopy (SEM) were used to observe the microstructure of the samples. Cracks were observed to initiate at the surface because the strains and stresses there were the largest during thermal cycling. Mechanical strain accelerated the damage and softening of the steel. A larger mechanical strain caused greater deformation of the steel, which made the precipitated carbides easier to gather and grow along the deformation direction, possibly resulting in softening of the material or the initiation of cracks.

关键词： tool steel hardness microstructure isothermal fatigue mechanical strain

人工智能在北方铁路口岸木材材积测量中的应用测试研究

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对外经贸 2024年第4期 81-84页

作者：刘磊左鹏刘韬张义满洲里海关内蒙古满洲里021400 哈尔滨海关黑龙江哈尔滨150090 不详

随着深度学习的开放,人工智能在近几年得到了快速发展。满洲里海关运用人工智能技术升级改造了铁路口岸木材材积测量系统。此套系统在满洲里铁路口岸原有木材材积测量系统的基础上,引入人工智能技术,采用深度卷积神经网络,实现对木材材... 详细信息

随着深度学习的开放,人工智能在近几年得到了快速发展。满洲里海关运用人工智能技术升级改造了铁路口岸木材材积测量系统。此套系统在满洲里铁路口岸原有木材材积测量系统的基础上,引入人工智能技术,采用深度卷积神经网络,实现对木材材积智能、快速、准确识别。研究结果表明,人工智能技术在北方铁路口岸木材材积测量系统中具有广泛的应用前景,可有效降低人工误差及劳动强度,避免作业风险,为北方铁路口岸海关查验作业提质增效提供了科技装备创新的探索方向。

关键词：木材材积测量人工智能卷积神经网络海关监管

The performance of a combined nitritation–anammox reactor treating anaerobic digestion supernatant under various C/N ratios

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Journal of Environmental Sciences 2015年第4期27卷 207-214页

作者： Jian Zhao Jiane zuo Jia Lin peng Li State Key Joint Laboratory of Environment Simulation and Pollution Control School of Environment Tsinghua University

A combined nitritation–anammox reactor was developed to treat the digestion supernatant under various C/N ratios. Due to the difficulties for heterotroph to utilize the refractory organics, the reactor presented relatively stable performance with increasing supernatant addition. Nevertheless, the adverse effects of supernatant would accumulate during the long-term operation and thus weakened the activity and shock resistance of microbes,which further led to the gradual decrease of reactor performance after 92 days＇ *** this circumstance, supernatant with volatile fatty acids（VFAs） residuals was further introduced into the reactor to investigate the performance of combined nitritation–anammox process with VFA addition. With the appearance of VFAs, the nitrogen removal performance gradually restored and the reactor finally achieved stable and efficient performance with C/N ratio of 0.35. The VFA residuals within 150 mg/L in the supernatant served as the extra electron donors and stimulated the heterotrophic denitrification process, which was vital for the enhancement of reactor. The nitrogen removal rate and total nitrogen removal efficiency reached 0.49 kg N/（m^3·day） and 88.8% after 140 days＇ operation, respectively. The combined nitritation–anammox reactor was proved suitable to treat digestion supernatant.

关键词： Combined nitritation–anammox Anaerobic digestion supernatant C/N ratios Volatile fatty acids

分析高龄产妇胎儿先天畸形超声筛查及危险因素

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罕少疾病杂志 2024年第2期31卷 89-90,97页

作者：李倩张丽左云鹏徐州市妇幼保健院江苏徐州221000

目的分析高龄产妇产前筛查胎儿畸形情况及其危险因素。方法收集2019年1月-2022年1月中晚孕胎儿产前筛查高龄孕妇的超声检查结果,畸形组和正常组,分析两组研究对象的临床资料,对P<0.05有统计学意义的单因素结果,采用Logistic多元回归分... 详细信息

目的分析高龄产妇产前筛查胎儿畸形情况及其危险因素。方法收集2019年1月-2022年1月中晚孕胎儿产前筛查高龄孕妇的超声检查结果,畸形组和正常组,分析两组研究对象的临床资料,对P<0.05有统计学意义的单因素结果,采用Logistic多元回归分析。结果306例孕妇中,胎儿畸形占比11.44%,畸形组和正常组孕妇在文化程度、不良妊娠史、孕期合并症、饮酒/吸烟史、接触有害物质、普通感冒发热、病毒感染、服用叶酸、服药方面比较差异有统计学意义。文化程度初中及以下、孕期合并症、孕期饮酒/吸烟史、孕期接触有害物质、孕期普通感冒发热、孕期病毒感染、孕期服药是影响胎儿畸形发生的独立危险因素;孕期服用叶酸是影响胎儿畸形发生的独立保护因素。结论高龄产妇畸形发生率较高且危险因素众多,临床需要加强高龄孕妇的产前筛查,提前做好防治方案,改善妊娠结局。

关键词：高龄产妇产前筛查胎儿畸形高危因素

维普期刊数据库博看期刊

超声弹性成像联合血清CK19、CEA水平在乳腺癌腋窝淋巴结转移中的诊断价值研究

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河北医科大学学报 2024年第4期45卷 472-476页

作者：李倩张丽左云鹏江苏省徐州市妇幼保健院超声科江苏徐州221000

目的研究超声弹性成像联合血清细胞角蛋白19(cytokeratin 19,CK19)、癌胚抗原(carcino-embryonic antigen,CEA)水平在乳腺癌腋窝淋巴结转移中的诊断价值。方法回顾性分析女性乳腺癌患者74例的临床资料。根据术后病理检查结果是否有腋窝... 详细信息

目的研究超声弹性成像联合血清细胞角蛋白19(cytokeratin 19,CK19)、癌胚抗原(carcino-embryonic antigen,CEA)水平在乳腺癌腋窝淋巴结转移中的诊断价值。方法回顾性分析女性乳腺癌患者74例的临床资料。根据术后病理检查结果是否有腋窝淋巴结转移将其分为转移组(32例)与非转移组(42例)。比较2组超声弹性成像评分;分析超声弹性成像诊断乳腺癌腋窝淋巴结转移的价值;比较2组CK19、CEA水平;分析CK19、CEA对乳腺癌腋窝淋巴结转移的诊断价值;以病理诊断结果为金标准,分析超声弹性成像联合CK19、CEA诊断乳腺癌腋窝淋巴结转移的价值。结果转移组中超声弹性成像评分1、2分所占比例明显低于非转移组,3、4分所占比例明显高于非转移组(P<0.05)。超声弹性成像诊断乳腺癌腋窝淋巴结转移的敏感度为0.781,特异度为0.952,准确率为0.878。转移组CK19、CEA水平明显高于非转移组(P<0.05)。CK19、CEA诊断乳腺癌腋窝淋巴结转移的曲线下面积为0.922、0.916,敏感度为0.875、0.844,特异度为0.857、0.929,P<0.05。超声弹性成像联合CK19、CEA诊断乳腺癌腋窝淋巴结转移的敏感度为0.938,特异度为0.905,准确率为0.919。结论超声弹性成像联合CK19、CEA诊断乳腺癌腋窝淋巴结转移的价值高于其单独诊断的价值,临床可对其密切关注。

关键词：乳腺肿瘤弹性成像技术角蛋白19 癌胚抗原

维普期刊数据库博看期刊

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六横岛邻近海域潮汐潮流特征分析

海洋湖沼通报 2024年第2期46卷 71-81页

作者：孙永钊纪棋严苏毓张洁彭腾腾左军成浙江海洋大学海洋科学与技术学院浙江舟山316022 上海海洋大学海洋科学与生态环境学院上海201306

基于FVCOM海洋模式,对六横岛邻近海域建立高分辨率的三维海洋数值模型。精细化模拟了六横岛邻近海域潮汐、潮流的主要特征,模式结果同1个验潮站与2个测流站观测资料吻合明显,可以反映六横岛邻近海域潮汐、潮流运动特征,同时给出了M_(2)... 详细信息

基于FVCOM海洋模式,对六横岛邻近海域建立高分辨率的三维海洋数值模型。精细化模拟了六横岛邻近海域潮汐、潮流的主要特征,模式结果同1个验潮站与2个测流站观测资料吻合明显,可以反映六横岛邻近海域潮汐、潮流运动特征,同时给出了M_(2)、S_(2)、K_(1)、O_(1)、M_(4)、M_(6)等4个主要分潮同潮图与表层潮流椭圆空间分布以及2个浅水分潮同潮图,并分析了潮汐类型系数、最大可能潮差以及潮汐不对称现象分析,最后分析了涨急、落急、涨憩、落憩等经典潮况的表层流场以及表层、0.6 h层、底层的余流空间分布。分析表明,M_(2)、S_(2)、O_(1)分潮均呈南高北低的分布特征,空间分布上M_(2)、S_(2)、O_(1)振幅分别为115~145、15~30、19~24 cm,而K_(1)分潮空间分布无显著特征,振幅在20~30 cm,且主要分潮传播方向一致,均以东海前进波形式传入,对M_(4)、M_(6)分潮振幅分别为2~20、1~6 cm,同时空间分布特征和传播方向与主要分潮相反。基于调和分析结果计算潮型系数与最大可能潮差,整个海域呈正规半日潮性质且最大可能潮差南部海域可达600~650 cm,北部海域则在450~550 cm;通过计算潮汐不对称性,六横南部海域落潮速度大于涨潮速度,北部相反。4个潮况下,落急流场最大,最大可达220 cm/s,而四个主要分潮最大流速分别在160、60、22、12 cm/s,空间分布上均为外海旋转流、近岸往复流的特征;余流的分布上,表层、0.6 h层、底层在岬角处最大可达25 cm/s,但随水深升高余流逐渐减弱。

关键词： FVCOM 调和分析潮汐不对称现象潮流椭圆余流