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东欧地区高速公路组合钢管支架预压关键技术

公路 2024年第2期69卷 91-95页

作者：唐琦危志豪南维州张庆祎东南大学建筑设计研究院有限公司南京市210096 中交一公局集团有限公司北京市100024

支架预压作为一种被成功验证的手段,能有效地消除支架体系间的非弹性变形,现已被广泛运用于现代工程之中。在以欧标建设的黑山南北高速公路项目中,由于技术要求的特殊性,其有别于国内预压技术。通过结合Jabuka桥工程实例,介绍在东欧地... 详细信息

支架预压作为一种被成功验证的手段,能有效地消除支架体系间的非弹性变形,现已被广泛运用于现代工程之中。在以欧标建设的黑山南北高速公路项目中,由于技术要求的特殊性,其有别于国内预压技术。通过结合Jabuka桥工程实例,介绍在东欧地区进行现浇梁组合钢管支架预压施工的关键技术及注意事项。同时,也为后续类似国际工程提供参考及借鉴。

关键词：桥梁施工设备东欧地区组合钢管支架预压

Study on the long-distance target apperception techniques for underwater vehicles

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Journal of Systems Engineering and Electronics 2007年第3期18卷 484-490页

作者： Yang Xudong Huang Jianguo Zhang Qunfei tang qi Dept. of Electronics and Communication Engineering Coll. of Marine Engineering Northwestern Polytechnical Univ. Xi'an 710072 P. R. China

The limited physical size for autonomous underwater vehicles （AUV） or unmanned underwater vehicles （UUV） makes it difficult to acquire enough space gain for localizing long-distance targets. A new technique about long-distance target apperception with passive synthetic aperture array for underwater vehicles is presented. First, a synthetic aperture-processing algorithm based on the FFT transform in the beam space （BSSAP） is introduced. Then, the study on the flank array passive long-distance apperception techniques in the frequency scope of 11-18 kHz is implemented from the view of improving array gains, detection probability and augmenting detected range under a certain sea environment. The results show that the BSSAP algorithm can extend the aperture effectively and improve detection probability. Because of the augment of the transmission loss, the detected range has the trend of decline with the increase of frequency under the same target source level. The synthesized array could improve the space gain by nearly 7 dB and SNR is increased by about 5 dB. The detected range is enhanced to nearly 2 km under the condition of 108-118 dB of the target source level for AUV system in measurement interval of nearly 1 s.

关键词： long-distance apperception synthetic aperture processing array gain detection probability detectedrange.

Dual characteristic of trace rare earth elements in a commercial casting Al-Cu-X alloy

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Rare Metals 2015年第5期34卷 308-313页

作者： Li Fan qi-tang Hao Wen-Ke Han State Key Laboratory of Solidification Processing Northwestern Polytechnical University School of Materials Science and Engineering Northwestern Polytechnical University

The effect of rare earth elements on microstructure and mechanical properties of casting Al-Cu-X alloy （X = Mn, Ti, V, Cd, Zr） was investigated in as-cast and T6 conditions. Microstructure evolution was characterized by optical microscopy, scanning electron microscopy, and transmission electron microscopy. RE-containing intermetallic compounds （IMCs） formed in this alloy were indentified by X-ray diffraction （XRD） and energy dispersive spectroscopy （EDS）. It is shown that the additions of RE （60Ce-40La, wt%） result in the formation of Ce-rich blocky-shaped A12o（Ti, V）2RE and La-rich skeletal-shaped A18Cu4RE. Tensile results of samples after T6 treatment indicate that the strength and ductility increase slightly to 480 MPa and 9.7 %, respectively, with RE content increasing from 0 wt% to 0.3 wt%. This is due to the combinative hardening effects of reduced grain size, enhanced precipitation of 0＇（Al2Cu） phase and Al20 Cu2Mn3 dispersed particles, and minor La-rich IMCs at the grain boundaries of α-Al dendrites. The decrease of strength of 0.5 wt% RE-added sample is ascribed to the aggregation of Al20（Ti, V）2RE IMCs inside the grains. The dual characteristic of rare earth elements was also discussed in terms of its positive and negative effects on mechanical properties.

关键词： Aluminum alloys Rare earth Microstructure Mechanical property Intermetallic compounds

响应面法优化罂粟科植物叶片原生质体的制备条件

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云南农业大学学报（自然科学版） 2024年第2期39卷 119-129页

作者：邵瑛瑛唐其彭晓英黄子豪郑亚杰湖南农业大学园艺学院湖南长沙410128 国家植物功能成分利用工程技术研究中心湖南长沙410128 湖南农业大学生物科学技术学院湖南长沙410128

【目的】系统优化罂粟科(Papaveraceae)植物叶片原生质体提取的影响因素,建立其高效的原生质体提取体系。【方法】以花菱草(Eschscholtzia californica Cham.)幼苗为罂粟科模式植物,通过单因素试验对影响原生质体产量和活力的预制液浓... 详细信息

【目的】系统优化罂粟科(Papaveraceae)植物叶片原生质体提取的影响因素,建立其高效的原生质体提取体系。【方法】以花菱草(Eschscholtzia californica Cham.)幼苗为罂粟科模式植物,通过单因素试验对影响原生质体产量和活力的预制液浓度、酶解液组成、酶解时间进行考察,借助响应面Box-Behnken设计预测最佳提取方案,并将最佳方案在罂粟亚科(Papaveroideae)、角茴香亚科(Hypecooideae)和荷包牡丹亚科(Fumarioideae)的代表性植物中进行验证。【结果】当预制液浓度为0.8 mol/L、酶解时间6 h、酶解液组成为1.5%纤维素酶+0.4%离析酶+0.3%果胶酶时,花菱草原生质体的产量和活力最为理想,与响应面法的预测结果一致,能够成功获取罂粟科植物叶片的原生质体。【结论】本研究方法可实现罂粟科植物叶片原生质体的高效提取,为后续瞬时表达体系、亚细胞定位、单细胞测序等研究提供技术支撑。

关键词：罂粟科原生质体酶解法单因素试验 Box-Behnken响应面法

Casting of aluminum-copper based alloy by controled difusion solidiication

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China Foundry 2015年第2期12卷 92-98页

作者： Li Fan qi-tang Hao Rui-qi Shen State Key Laboratory of Solidification Processing Northwestern Polytechnical University

A quaternary alloy （Al-5.0Cu-0.35Mn-0.25Ti, wt.%）, having a similar chemical component with ZL205A, was prepared using a controlled diffusion solidification （CDS） process and a conventional casting process. The effect of the casting process on microstructure and hardness was investigated. The grain morphology and casting defects of the al oy prepared via the conventional casting and CDS were observed and compared at various pouring temperatures. Results show that the CDS process can al eviate the hot tearing defects and reduce the density of porosity, while getting rid of the riser that is general y used for feeding during conventional casting. Structure observations show that the grain morphology of the conventional cast al oy is mainly dendritic, and the grain size decreases when the pouring temperature is decreased, while the CDS cast al oy consists of a large number of spherical grains, which can decrease the thermal cracking tendency and segregation defect, and enhance the hardness of the alloy.

关键词： Al alloys conventional casting controlled diffusion solidifi cation casting defect microstructure

On Parametric Instability Boundaries of Axially Moving Beams with Internal Resonance

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Acta Mechanica Solida Sinica 2018年第4期31卷 470-483页

作者： You-qi tang Yuan-Xun Zhang Xiao-Dong Yang School of Mechanical Engineering Shanghai Institute of Technology Shanghai 201418 China Beijing Key Laboratory of Nonlinear Vibrations and Strength of Mechanical Engineering College of Mechanical Engineering Beijing University of Technology Beijing 100124 China

In this paper, the instability boundaries of an axially moving viscoelastic beam due to parametric resonance are revisited for the internal resonance case. The relation between the time-dependent tension and the time-dependent axial speed is constructed, which provides a new model in the study of axially moving material with pulsation parameters. The instability boundaries caused by the combination of parametric and internal resonances are studied using the method of multiple time scales. Some strange instability boundaries are detected when the internal resonance is considered. The phenomenon of local zigzag boundary contour is explained from the viewpoint of modal interactions.

关键词： Parametric stability Axially moving beam Instability boundary Modal interac-tions

缺血性结肠炎严重程度的影响因素分析及预测模型构建

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江苏医药 2024年第2期50卷 141-146页

作者：姚悦汤淇柯毅恒阮水良浙江中医药大学嘉兴学院联培基地浙江嘉兴314000 嘉兴学院附属第二医院消化内科

目的探讨缺血性结肠炎(IC)严重程度的影响因素及预测模型的构建。方法269例IC患者分为轻症组(220例)和重症组(49例)。比较两组患者的临床资料。采用多因素logistic回归分析重症IC的影响因素。构建预测模型,采用ROC曲线分析其预测价值。... 详细信息

目的探讨缺血性结肠炎(IC)严重程度的影响因素及预测模型的构建。方法269例IC患者分为轻症组(220例)和重症组(49例)。比较两组患者的临床资料。采用多因素logistic回归分析重症IC的影响因素。构建预测模型,采用ROC曲线分析其预测价值。结果重症组男性、腹部手术史、便秘、陈旧性脑梗死、腹胀、腹部压痛比例及C反应蛋白、白细胞计数、中性粒细胞百分比、中性粒细胞绝对值、红细胞分布宽度、中性粒细胞与淋巴细胞比值(NLR)、血小板与淋巴细胞比值、血清肌酐、D-二聚体均高于轻症组(P<0.05),淋巴细胞百分比、淋巴细胞绝对值、钠离子和血便比例低于轻症组(P<0.05)。采用多因素logistic回归分析构建预测模型,方程式为―5.276+0.960×腹部手术史+0.076×NLR―1.364×血便+1.656×腹部压痛+0.030×血清肌酐+0.480×D-二聚体。既往手术史、腹部压痛以及NLR、血清肌酐和D-二聚体较高是重症IC的独立危险因素(P<0.05),血便是重症IC的独立保护性因素(P<0.05)。ROC曲线显示,预测模型预测重症IC的AUC为0.840,其预测的灵敏度为91.8%,特异度为61.4%。结论既往手术史、腹部压痛、血便、NLR、血清肌酐和D-二聚体是重症IC的独立影响因素。构建的预测模型有较好的临床价值。

关键词：缺血性结肠炎预测模型

改良面罩联合HFNC在心脏术后低氧血症病人中的疗效探讨

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蚌埠医学院学报 2024年第7期49卷 927-932,937页

作者：董敏陈永侠陈娜汤琪蚌埠医科大学护理学院安徽蚌埠233030 蚌埠医科大学第一附属医院护理部安徽蚌埠233004

目的:探讨改良面罩对接受经鼻高流量氧疗(HFNC)的心脏手术后低氧血症病人的疗效。方法:选取68例心脏手术病人,在气管插管拔除后出现低氧血症时被纳入研究,采用数字表格法随机分为2组,分别采用经鼻高流量氧疗(HFNC)和改良面罩联合经鼻高... 详细信息

目的:探讨改良面罩对接受经鼻高流量氧疗(HFNC)的心脏手术后低氧血症病人的疗效。方法:选取68例心脏手术病人,在气管插管拔除后出现低氧血症时被纳入研究,采用数字表格法随机分为2组,分别采用经鼻高流量氧疗(HFNC)和改良面罩联合经鼻高流量氧疗(HFNC)进行呼吸治疗。比较2组在不同时间点(治疗前、治疗后0.5 h、1 h、6 h、24 h)的呼吸和循环方面情况,以及机械通气再次插管率、治疗时间、ICU停留时间和总住院时间、肺部感染发生率和住院死亡率。结果:与HFNC组相比,改良面罩联合HFNC组在提高氧分压(PaO_(2))和改善氧合指数(PaO_(2)/FiO_(2))及降低呼吸频率(RR)方面差异有统计学意义(P0.05)。改良面罩联合HFNC组机械通气再插管率低于HFNC组,治疗时间和ICU停留时间明显短于HFNC组(P0.05)。结论:在心脏手术后急性低氧血症病人中,将改良面罩和HFNC联合使用可提高PaO_(2)而不增加PaCO_(2),进一步改善氧合和循环,减少治疗时间、机械通气再插管率和ICU停留时间,但2组总住院时间、肺部感染发生率和住院死亡率无明显差异。

关键词：心脏手术低氧血症改良面罩经鼻高流量氧疗

Tomographic PIV investigation of coherent structures in a turbulent boundary layer flow

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Acta Mechanica Sinica 2012年第3期28卷 572-582页

作者： Zhan-qi tang Nan Jiang Andreas Schroder Reinhard Geisler Department of Mechanics Tianjin University300072 TianjinChina Tianjin Key Laboratory of Modern Engineering Mechanics 300072 TianjinChina Institute of Aerodynamics and Flow Technology Department of Experimental MethodsBunsenstrasse 1037073 GiSttingenGermany

Tomographic particle image velocimetry was used to quantitatively visualize the three-dimensional co- herent structures in the logarithmic region of the turbulent boundary layer in a water tunnel. The Reynolds number based on momentum thickness is Reo = 2 460. The in- stantaneous velocity fields give evidence of hairpin vortices aligned in the streamwise direction forming very long zones of low speed fluid, which is flanked on either side by high- speed ones. Statistical support for the existence of hairpins is given by conditional averaged eddy within an increasing spanwise width as the distance from the wall increases, and the main vortex characteristic in different wall-normal re- gions can be reflected by comparing the proportion of ejec- tion and its contribution to Reynolds stress with that of sweep event. The pre-multiplied power spectra and two-point cor- relations indicate the presence of large-scale motions in the boundary layer, which are consistent with what have been termed very large scale motions （VLSMs）. The three dimen-sional spatial correlations of three components of veloc- ity further indicate that the elongated low-speed and high- speed regions will be accompanied by a counter-rotating roll modes, as the statistical imprint of hairpin packet structures, all of which together make up the characteristic of coherent structures in the logarithmic region of the turbulent boundary layer （TBL）.

关键词： Tomographic particle image velocimetry Tur-bulent boundary layer Coherent structures Hairpin vortex Very large scale motion