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Confining pressure effect on dynamic response of high rockfill dam

Xuexing CAO, Yunlong HE, Kun XIONG,

《结构与土木工程前沿（英文）》 2010年 第4卷 第1期   页码 116-126 doi: 10.1007/s11709-010-0014-5

摘要： Studies show that the dynamic properties of rockfill are strongly dependent on the confining pressure. Therefore, confining pressure effect has become a very important factor in the seismic analysis of high rockfill dam. The relationships of dynamic shear modulus versus dynamic shear strain and damping ratio versus dynamic shear strain had been improved to a certain degree on the basic of widely used Hardin-Drnevich constitutive model in this paper. Then a new model that could consider confining pressure effect has been established. Regression analysis was carried out of the dynamic triaxial experimental data of the damming materials in the Changheba hydropower station of Sichun Province, China. The results show that, the new model can fit the test data well under various confining pressures. A corresponding computational procedure was compiled and applied in the dynamic response analysis of the Changheba Dam. Comparing the calculation results between the new constitutive model and the ordinary Hardin-Drnevich model, it can be seen that the result is conservative to some extent without considering confining pressure effect.

关键词： confining pressure effect     high rockfill dam     dynamic response     Hardin-Drnevich constitutive model    

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三向应力状态下混凝土强度和变形特性研究

闫东明,林皋

《中国工程科学》 2007年 第9卷 第6期   页码 64-70

摘要：

对设计强度为10MPa的混凝土立方体试件进行三轴压缩试验，系统研究了等围压条件下混凝土的强 度和变形特性，围压分别为0，4，8，12，16MPa５个量级；同时研究了不等围压条件下混凝土强度变化特性， 试验表明，随着围压增加，混凝土的极限抗压强度有明显增强的趋势；随着小主应力的增加，中主应力的影响 有减弱的趋势；峰值应力处应变随围压增加幅度显著。得出了在不同恒定围压下混凝土的应力应变全过程曲线； 通过与当前文献资料的对比分析，指出了在混凝土结构计算中适用的强度及变形表达式，为工程实践提供了 依据。

关键词： 三向受力状态     不等围压     极限强度     变形     混凝土    

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Effect of pressure on gasification reactivity of three Chinese coals with different ranks

Chunyu LI, Jiantao ZHAO, Yitian FANG, Yang WANG

《化学科学与工程前沿（英文）》 2010年 第4卷 第4期   页码 385-393 doi: 10.1007/s11705-010-0501-1

摘要： The gasification reactivities of three kinds of different coal ranks (Huolinhe lignite, Shenmu bituminous coal, and Jincheng anthracite) with CO and H O was carried out on a self-made pressurized fixed-bed reactor at increased pressures (up to 1.0 MPa). The physicochemical characteristics of the chars at various levels of carbon conversion were studied via scanning electron microscopy (SEM), X-ray diffraction (XRD), and BET surface area. Results show that the char gasification reactivity increases with increasing partial pressure. The gasification reaction is controlled by pore diffusion, the rate decreases with increasing total system pressure, and under chemical kinetic control there is no pressure dependence. In general, gasification rates decrease for coals of progressively higher rank. The experimental results could be well described by the shrinking core model for three chars during steam and CO gasification. The values of reaction order with steam were 0.49, 0.46, 0.43, respectively. Meanwhile, the values of reaction order with CO were 0.31, 0.28, 0.26, respectively. With the coal rank increasing, the pressure order is higher, the activation energies increase slightly with steam, and the activation energy with CO increases noticeably. As the carbon conversion increases, the degree of graphitization is enhanced. The surface area of the gasified char increases rapidly with the progress of gasification and peaks at about 40% of char gasification.

关键词： coal     gasification     pressure     reaction order     shrinking core model    

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Using mRNA to investigate the effect of low-pressure ultraviolet disinfection on the viability of

Chao Yang, Wenjun Sun, Xiuwei Ao

《环境科学与工程前沿（英文）》 2019年 第13卷 第2期 doi: 10.1007/s11783-019-1111-x

摘要：

UV can induce damages on mRNA consistently among different genes.

SOS response was more active after UV treatment.

Programmed cell death was not found to be more active after UV treatment.

关键词： UV disinfection     Viability     mRNA     SOS response     Programmed cell death    

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Experiments on the effect of the pressure on the mineral transformation of coal ash under the different

Nijie JING, Qinhui WANG, Zhongyang LUO, Tao JIE, Xiaomin LI, Kefa CEN

《化学科学与工程前沿（英文）》 2010年 第4卷 第4期   页码 394-399 doi: 10.1007/s11705-010-0505-x

摘要： This paper investigated the effect of the pressures, reaction atmospheres and coal ash species on the ash fusibility with high-pressure thermogravimetric analysis (PTGA) apparatus and X-ray diffraction (XRD) analysis. Each specimen analyzed by XRD was observed for the mineral conversion and formation of new minerals with the pressures under different atmospheres. These results indicate that the pressure restrains the transformation and decomposition of minerals. Many low-temperature minerals are still present under the elevated pressure. The different reaction atmospheres have different effects on the formation of coal ash minerals. Under the N atmosphere, the present microcline may decrease the melting temperature of coal ash. And later, it transforms into sanidine at high pressure; thus, the melting temperature of coal ash may increase. Under the CO atmosphere, the minerals such as microcline, lomonitite, geothite and illite are still present with the increase in pressure; this may reduce the melting temperature. While under the H O atmosphere, there are magnetite and anorthoclase, which may produce the low-temperature eutectics decreasing the melting temperature. The coal ash abundance in basic oxides or higher SiO , Fe O , K O and Na O has lower melting temperature. While the ash sample with more SiO and Al O and less Fe O and basic oxides may lead to higher melting temperature.

关键词： ash fusibility     XRD analysis     PTGA     low-temperature eutectic    

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Rheological behavior’s effect on the work performance of oil film

Zhaomiao LIU, Qiuying JIN, Chengyin ZHANG, Feng SHEN

《机械工程前沿（英文）》 2011年 第6卷 第2期   页码 254-262 doi: 10.1007/s11465-011-0129-y

摘要：

A 3D model of hydrostatic turntable’s oil chamber is established to investigate the lubricants performance with different rheological properties by using FLUENT software and the finite volume method. Newtonian oil and non-Newtonian oil’s performance under varied speeds are compared on the large size hydrostatic turntable system considering the temperature-viscosity relationship and pressure-viscosity relationship. The results show that the property of non-Newtonian fluid viscosity influenced by shear rate largely affects the lubricants performance for most oil added polymer additives. Lubricants cannot simply be regarded as Newtonian fluid. The shear thickening non-Newtonian fluid has a better work property. The results are important to design a large size and high-speed hydrostatic support system, choose lubricant oils, and investigate oil film’s work properties.

关键词： non-Newtonian fluid     rotation speed     pressure on wall     viscosity    

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Effect of cutterhead configuration on tunnel face stability during shield machine maintenance outages

《结构与土木工程前沿（英文）》 2023年 第17卷 第4期   页码 522-532 doi: 10.1007/s11709-023-0930-9

摘要： Owing to long-distance advancement or obstacles, shield tunneling machines are typically shut down for maintenance. Engineering safety during maintenance outages is determined by the stability of the tunnel face. Pressure maintenance openings are typically used under complicated hydrogeological conditions. The tunnel face is supported by a medium at the bottom of the excavation chamber and compressed air at the top. Owing to the high risk of face failure, the necessity of support pressure when cutterhead support is implemented and a method for determining the value of compressed air pressure using different support ratios must to be determined. In this study, a non-fully chamber supported rotational failure model considering cutterhead support is developed based on the upper-bound theorem of limit analysis. Numerical simulation is conducted to verify the accuracy of the proposed model. The results indicate that appropriately increasing the specific gravity of the supporting medium can reduce the risk of collapse. The required compressed air pressure increases significantly as the support ratio decreases. Disregarding the supporting effect of the cutterhead will result in a tunnel face with underestimated stability. To satisfy the requirement of chamber openings at atmospheric pressure, the stratum reinforcement strength and range at the shield end are provided based on different cutterhead aperture ratios.

关键词： tunnel face stability     cutterhead configuration     aperture ratio     pressure gradient     support ratio    

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隐覆型岩溶地基稳定性分析与压浆预处理

孙成访,杨安蓉,董汉雄,彭少民

《中国工程科学》 2002年 第4卷 第7期   页码 56-59

摘要：

通过对隐覆型岩溶地基稳定性的分析，采用压浆法预处理隐覆型岩溶地基，并对压浆效果进行了分析评价，研究结果表明, 压浆预处理隐覆型岩溶地基在技术上和经济上是可行的。

关键词： 岩溶地基     压力压浆     效果评价    

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Effect of Ca

Qi WANG, Hongzhi JIANG, Shengli CHEN, Mingmin ZHANG, Mingxing DING, Esheng KONG, Guangying HUANG

《医学前沿（英文）》 2009年 第3卷 第1期   页码 96-99 doi: 10.1007/s11684-009-0014-9

摘要： The aim of this paper was to explore the relationship between energy metabolism and the meridian phenomenon. The manner of change of oxygen partial pressure in acupoints and no-acupoints of the urinary bladder meridian of goats was observed with a needle-type tissue oxygen tension sensor after the acupuncture effect was blocked by Ca complexation with ethylenediamine tetraacetic acid (EDTA)-Na . The results showed that: (1) the concentration of calcium ion in urinary bladder meridian acupoints was higher than that in no-acupoints ( <0.01 or <0.05); (2) the tissue oxygen tension in urinary bladder meridian acupoints was higher than that in no-acupoints ( <0.01); (3) the oxygen partial pressure in acupoints decreased significantly after injection with EDTA-Na , compared with injection of either normal sodium or nothing ( <0.01); (4) the oxygen partial pressure in acupoints was higher than that in no-acupoints after EDTA-Na injection ( <0.01). Acupuncture could reduce oxygen partial pressure in acupoints by regulating microcirculation and increasing metabolic levels.

关键词： oxygen partial pressure     biosensor     calcium channels     acupoint    

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Modelling and experimental verification on concrete-filled steel tubular columns with L or T section

LU Xilin, LI Xueping, WANG Dan

《结构与土木工程前沿（英文）》 2007年 第1卷 第2期   页码 163-169 doi: 10.1007/s11709-007-0017-z

摘要： Concrete-filled steel tubular columns with L or T sections were analyzed in this paper. According to the confining mechanism, the stress-strain constitutive model was put forward, and calculated results were compared with experimental records. After that, the hysteretic rules for the in-filled concrete were constructed, aiming at the analysis on the seismic behavior of composite members. The simulation analysis was performed by programming it in Fortran. The models in this paper can be applied in the program of time history analysis on tall buildings with concrete-filled steel tubular columns with L or T sections.

关键词： hysteretic     confining mechanism     Concrete-filled     in-filled     composite    

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Effect of different gas releasing methods on anaerobic fermentative hydrogen production in batch cultures

Sheng CHANG, Jianzheng LI, Feng LIU, Ze YU

《环境科学与工程前沿（英文）》 2012年 第6卷 第6期   页码 901-906 doi: 10.1007/s11783-012-0403-1

摘要： Decreasing hydrogen partial pressure can not only increase the activity of the hydrogen enzyme but also decrease the products inhibition, so it is an appropriate method to enhance the fermentative hydrogen production from anaerobic mixed culture. The effect of biogas release method on anaerobic fermentative hydrogen production in batch culture system was compared, i.e., Owen method with intermediately release, continuous releasing method, and continuous releasing+ CO absorbing. The experimental results showed that, at 35°C, initial pH 7.0 and glucose concentration of 10 g·L , the hydrogen production was only 28 mL when releasing gas by Owen method, while it increased two times when releasing the biogas continuously. The cumulative hydrogen production could reach 155 mL when carbon dioxide in the gas stream was continuously absorbed by 1 mol·L NaOH. The results showed that acetate was dominated, accounting for 43% in the dissolved fermentation products in Owen method, whereas the butyrate predominated and reached 47%–53% of the total liquid end products when releasing gas continuously. It is concluded that the homoacetogenesis could be suppressed when absorbing CO in the gas phase in fermentative hydrogen production system.

关键词： batch fermentation     hydrogen production     biogas releasing     hydrogen pressure     homoacetogenesis    

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Deviation correction strategy for the earth pressure balance shield based on shield–soil interactions

《机械工程前沿（英文）》 2022年 第17卷 第2期 doi: 10.1007/s11465-022-0676-4

摘要： The control system presently used in shield posture rectification is based on driver experience, which is marginally reliable. The study of the related theory is flawed. Therefore, a decision-making approach for the deviation correction trajectory and posture rectification load for an earth pressure balance (EPB) shield is proposed. A calculation model of posture rectification load of an EPB shield is developed by considering the interactions among the cutter head, shield shell, and ground. The additional position change during the shield attitude correction is highlighted. The posture rectification loads and shield behaviors results can be solved by the proposed method. The influences of the stratum distribution (i.e., bedrock height in the upper-soft and lower-hard strata) on shield behaviors and posture rectification loads are analyzed. Results indicated that the increase of pitch angle in the upper-soft and lower-hard strata causes a sharp rise in vertical displacement. The bedrock height increases the magnitudes of the required posture rectification moments when hr/D > 0.5. For a tunnel with hr/D ≤ 0.5, the variation of hr/D has little effect on the posture rectification moments. Finally, the posture rectifying curves based on the theoretical model are compared with the target ones based on the double circular arc interpolation method. The required results can be obtained regardless of the soil–rock compound stratum distribution. The maximum rectification moment in the rock layer is almost 12.6 times that in the soil layer. Overall, this study provides a valuable reference for moment determination and the trajectory prediction of posture rectification in compound strata.

关键词： additional position change     deviation correction trajectory     earth pressure balance shield     mechanical model     posture rectification    

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Combustion instability detection using the wavelet detail of pressure fluctuations

JI Junjie, LUO Yonghao

《能源前沿（英文）》 2008年 第2卷 第1期   页码 116-120 doi: 10.1007/s11708-008-0019-0

摘要： A combustion instability detection method that uses the wavelet detail of combustion pressure fluctuations is put forward. To confirm this method, combustion pressure fluctuations in a stoker boiler are recorded at stable and unstable combustion with a pressure transducer. Daubechies one-order wavelet is chosen to obtain the wavelet details for comparison. It shows that the wavelet approximation indicates the general pressure change in the furnace, and the wavelet detail magnitude is consistent with the intensity of turbulence and combustion noise. The magnitude of the wavelet detail is nearly constant when the combustion is stable, however, it will fluctuate much when the combustion is unstable.

关键词： comparison     wavelet approximation     pressure transducer     general pressure     consistent    

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Hydraulic fracturing pressure of concentric double-layered cylinder in cohesive soil

《结构与土木工程前沿（英文）》 2021年 第15卷 第4期   页码 937-947 doi: 10.1007/s11709-021-0754-4

摘要： This study aims to investigate hydrofracturing in double-layered soil through theoretical and experimental analysis, as multilayered soils where the difference in mechanical properties exists are generally encountered in practical engineering. First, an analytical solution for fracturing pressure in two different concentric regions of soil was presented based on the cavity expansion theory. Then, several triaxial hydraulic fracturing tests were carried out to validate the analytical solution. The comparison between the experimental and analytical results indicates the remarkable accuracy of the derived formula, and the following conclusions were also obtained. First, there is a linear relationship between the fracturing pressure and confining pressure in concentric double-layered cohesive soil. Second, when the internal-layer soil is softer than the external-layer soil, the presence of internal soil on the fracturing pressure approximately brings the weakening effect, and the greater strength distinction between the two layers, the greater the weakening effect. Third, when the internal-layer soil is harder than the external-layer soil, the existence of the internal-layer soil has a strengthening effect on the fracturing pressure regardless of the proportion of internal-layer soil. Moreover, the influence of strength distinction between the two layers on the fracturing pressure is significant when the proportion of internal-layer soil is less than half, while it’s limited when the proportion is more than half. The proposed solution is potentially useful for geotechnical problems involving aspects of cohesive soil layering in a composite formation.

关键词： hydraulic fracturing pressure     layered     cavity expansion theory     triaxial fracturing test     cohesive soil    

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Effect of sodium bicarbonate solution on methyltrimethoxysilane-derived silica aerogels dried at ambientpressure

Yujing Liu, Xiao Han, Balati Kuerbanjiang, Vlado K. Lazarov, Lidija Šiller

《化学科学与工程前沿（英文）》 2021年 第15卷 第4期   页码 954-959 doi: 10.1007/s11705-020-2028-4

摘要： Here we present an economical ambient pressure drying method of preparing monolithic silica aerogels from methyltrimethoxysilane precursor while using sodium bicarbonate solution as the exchanging solvent. We prepared silica aerogels with a density and a specific surface area of 0.053 g∙cm and 423 m ∙g , respectively. The average pore diameter of silica aerogels is 23 nm as the pore specific volume is 1.11 cm ∙g . Further, the contact angle between water droplet and the surface of silica aerogels in specific condition can be as high as 166°, which indicates a super-hydrophobic surface of aerogels.

关键词： silica aerogel     methyltrimethoxysilane     solvent exchange     sodium bicarbonate     trimethylchlorosilane     ambient pressure drying    

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标题 作者 时间 类型 操作

Confining pressure effect on dynamic response of high rockfill dam

Xuexing CAO, Yunlong HE, Kun XIONG,

期刊论文

三向应力状态下混凝土强度和变形特性研究

闫东明,林皋

期刊论文

Effect of pressure on gasification reactivity of three Chinese coals with different ranks

Chunyu LI, Jiantao ZHAO, Yitian FANG, Yang WANG

期刊论文

Using mRNA to investigate the effect of low-pressure ultraviolet disinfection on the viability of

Chao Yang, Wenjun Sun, Xiuwei Ao

期刊论文

Experiments on the effect of the pressure on the mineral transformation of coal ash under the different

Nijie JING, Qinhui WANG, Zhongyang LUO, Tao JIE, Xiaomin LI, Kefa CEN

期刊论文

Rheological behavior’s effect on the work performance of oil film

Zhaomiao LIU, Qiuying JIN, Chengyin ZHANG, Feng SHEN

期刊论文

Effect of cutterhead configuration on tunnel face stability during shield machine maintenance outages

期刊论文

隐覆型岩溶地基稳定性分析与压浆预处理

孙成访,杨安蓉,董汉雄,彭少民

期刊论文

Effect of Ca

Qi WANG, Hongzhi JIANG, Shengli CHEN, Mingmin ZHANG, Mingxing DING, Esheng KONG, Guangying HUANG

期刊论文

Modelling and experimental verification on concrete-filled steel tubular columns with L or T section

LU Xilin, LI Xueping, WANG Dan

期刊论文

Effect of different gas releasing methods on anaerobic fermentative hydrogen production in batch cultures

Sheng CHANG, Jianzheng LI, Feng LIU, Ze YU

期刊论文

Deviation correction strategy for the earth pressure balance shield based on shield–soil interactions

期刊论文

Combustion instability detection using the wavelet detail of pressure fluctuations

JI Junjie, LUO Yonghao

期刊论文

Hydraulic fracturing pressure of concentric double-layered cylinder in cohesive soil

期刊论文

Effect of sodium bicarbonate solution on methyltrimethoxysilane-derived silica aerogels dried at ambientpressure

Yujing Liu, Xiao Han, Balati Kuerbanjiang, Vlado K. Lazarov, Lidija Šiller

期刊论文