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Embankment dam foundation analysis for the decrease of internal erosion likelihood

Marc SMITH

《结构与土木工程前沿（英文）》 2012年第6卷第4期页码 431-436 doi: 10.1007/s11709-012-0183-5

摘要： A zoned embankment dam is founded on clay underlain by a sand deposit. Major seepage phenomena were noticed in the foundation downstream from the dam where the vertical seepage forces in the sand layer were expected to exceed the downward forces due to the overlying clay. Modern technologies were applied to delineate critical zones to help design optimal rehabilitation measures. A global electromagnetic survey was carried out to detect and map the main sources, pathways and exits of seepage. Based on these global findings, a more detailed analysis was then conducted to identify zones where thickness of the foundation clay is minimal, pore pressures in sand are higher and thus where the factor of safety against uplift is lower and internal erosion is more likely to occur. Clay thickness evaluation required the determination of land surface as well as clay-sand contact elevations. A laser airborne survey was performed to model the land surface elevation. Data concerning the clay-sand contact elevation came from the interpreted stratigraphy based on a series of boreholes and cone penetration tests. This data was combined in a geostatistical model along with the measured piezometric levels in the foundation. This resulted in a contour map showing factors of safety against uplift over the entire downstream area. The use of modern technologies, namely electromagnetic and laser surveys as well as geostatistical tools, was instrumental in defining the limits of an otherwise spread-out problem and to provide an optimal solution, in terms of costs and effectiveness, for the long-term stabilization of the foundation.

关键词： seepage detection geostatistical analysis dam monitoring internal erosion LIDAR survey

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Investigation of flow dynamics and decrease of vortex noise inside volute of centrifugal fans

LI Chunxi, WANG Songling

《能源前沿（英文）》 2008年第2卷第2期页码 235-240 doi: 10.1007/s11708-008-0040-3

摘要： The characteristics of three-dimension flow dynamics inside the volute of a G4-73No.8D centrifugal fan was simulated numerically using a computational fluid dynamics(CFD) technique. The generation, evolution, and noise of the vortex were investigated when cylinder-shaped and cone-cylinder-shaped anti-vortex rings were added separately. Numerical results showed that large-scale vortices were broken effectively and the flow fields inside the fan were more uniform with the two anti-vortex rings installed. Experimental results indicated A-sound level and spectrum noise of the refitted fan decreased and the two anti-vortex rings were effective in decreasing vortex noise. The cone-cylinder-shaped anti-vortex ring was more effective than the cylinder-shaped one in breaking large-scale vortexes and decreasing vortex noise.

关键词： cylinder-shaped evolution computational effective large-scale

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Setting up a heart rate alarm limit to decrease oculocardiac reflex during strabismus surgery in children

ZHANG Kangkang, GU Enhua, LU Junjie

《医学前沿（英文）》 2008年第2卷第3期页码 295-297 doi: 10.1007/s11684-008-0056-4

摘要： The aim of this paper is to investigate a method which may decrease the incidence and severity of oculocardiac reflex (OCR) without drugs. One hundred and sixty children undergoing strabismus surgery were allocated to two groups using double-blind randomization. OCR was defined as a decrease of more than 10% from the baseline heart rate during operation. An alarm sounded and a lamp flashed as soon as OCR occurred in group I, and neither of the above happened in group II. OCR occurred (1.151 ± 0.858) times in group I and (2.287 ± 1.371) times in group II ( < 0.05). Heart rate decreased by (23 ± 19) bpm in group I and (35 ± 28) bpm in group II ( < 0.05). The duration of OCR in group I and group II was (4.36 ± 4.26)s and (7.62 ± 6.41)s, respectively ( < 0.05). The recovery time for group I and group II was (15.36 ± 13.28)s and (32.36 ± 19.57)s, respectively ( < 0.05). The numbers of times of interruption were 8 in group I (10%) and 26 in group II (32%) ( < 0.01). This method significantly decreased the incidence and severity of OCR during strabismus surgery in children.

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Proposing two new methods to decrease lateral-torsional buckling in reduced beam section connections

Samira EBRAHIMI; Nasrin BAKHSHAYESH EGHBALI; Mohammad Mehdi AHMADI

《结构与土木工程前沿（英文）》 2022年第16卷第12期页码 1581-1598 doi: 10.1007/s11709-022-0886-1

摘要： Reduced web section (RWS) connections can prevent lateral-torsional buckling and web local buckling experienced by reduced beam section (RBS) connections. In RWS connections, removing a large portion of web can result in shear demand intolerance induced to plastic hinge region. The present study aims to resolve the problems of RBS and RWS connections by proposing two new connections: (1) RBS with stiffener (RBS-ST) and (2) RBS with reduced web (RW-RBS) connections. In the first connection (RBS-ST), a series of stiffeners is connected to the beam in the reduced flange region, while the second connection (RW-RBS) considers both a reduction in flanges and a reduction in web. Five beam-to-column joints with three different connections, including RBS, RBS-ST, and RW-RBS connections were considered and simulated in ABAQUS. According to the results, RBS-ST and RW-RBS connections can decrease or even eliminate lateral-torsional buckling and web local buckling in RBS connection. It is important to note that RW-RBS connection is more effective in long beams with smaller shear demands in the plastic hinge region. Moreover, results showed that RBS and RW-RBS connections experienced strength degradation at 4% to 5% drift, while no strength degradation was observed in RBS-ST connection until 8% drift.

关键词： RBS RBS-ST RW-RBS lateral-torsional buckling cyclic performance

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Grindability of high-temperature alloy with ceramic alumina wheels

ZHANG Hongxia, CHEN Wuyi, CHEN Zhitong

《机械工程前沿（英文）》 2008年第3卷第2期页码 139-145 doi: 10.1007/s11465-008-0040-3

摘要： The grindability of high-temperature alloy by using ceramic alumina wheels is studied on the basis of extensive analysis of the grinding force, grinding temperature, surface roughness and topography of ground surfaces, residual stress, hardness distribution of surface layer, and morphology of the surface layer from a metallographic point of view. The grinding burn mechanism of high-temperature alloy is unveiled and the feasible grinding parameters to avoid burning are analyzed. Some conclusions are obtained as follows. Increasing the grinding depth or the wheel velocity makes grinding temperature and residual tensile stress of the surface rise, which deteriorates the surface topography. Appropriate liner velocity of the wheel is 18–22 m/s and the depth of grinding should not exceed 0.02 mm in grinding GH2132 alloy with ceramic alumina wheels to assure the surface quality. When increases enough to cause grinding burn, the strengthening effect of particles ′ in base decrease and the micro-hardness of the surface is obviously lower than that of the base material, which deteriorates the mechanical properties and heat resistance of GH2132 alloy. Results provide a theoretical and experimental basis for technical optimization in the grinding of high-temperature alloy with high efficiency and high quality.

关键词： metallographic topography grinding GH2132 resistance decrease

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Numerical analysis on heat transfer enhancement by longitudinal vortex based on field synergy principle

WU Junmei, TAO Wenquan

《能源前沿（英文）》 2007年第1卷第3期页码 365-369 doi: 10.1007/s11708-007-0055-1

摘要： Three-dimensional numerical simulation results are presented for a fin-and-tube heat transfer surface with vortex generators. The effects of the Reynolds number (from 800 to 2 000) and the attack angle (30º and 45º) of a delta winglet vortex generator are examined. The numerical results are analyzed on the basis of the field synergy principle to explain the inherent mechanism of heat transfer enhancement by longitudinal vortex. The secondary flow generated by the vortex generators causes the reduction of the intersection angle between the velocity and fluid temperature gradients. In addition, the computational evaluations indicate that the heat transfer enhancement of delta winglet pairs for an aligned tube bank fin-and-tube surface is more significant than that for a staggered tube bank fin-and-tube surface. The heat transfer enhancement of the delta winglet pairs with an attack angle of 45º is larger than that with an angle of 30º. The delta winglet pair with an attack angle of 45º leads to an increase in pressure drop, while the delta winglet pair with the 30º angle results in a slight decrease. The heat transfer enhancement under identical pumping power condition for the attack angle of 30º is larger than that for the attack angle of 45º either for staggered or for aligned tube bank arrangement.

关键词： computational inherent mechanism staggered decrease transfer surface

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新世纪的精细化工

杨锦宗

《中国工程科学》 2002年第4卷第10期页码 21-25

摘要：

指出精细化工是衡量化学工业水平的一个标志，提出并讨论了发展精细化工必须考虑的，包括环境保护、降低消耗、节约能源、合成关键技术、专用化技术、资源和科技创新等问题。

关键词：环境保护关键技术节能专用化技术科技创新

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Effects of MgO promoter on properties of Ni/Al2O3 catalysts for partial oxidation of methane to syngas

QIU Yejun, CHEN Jixiang, ZHANG Jiyan

《化学科学与工程前沿（英文）》 2007年第1卷第2期页码 167-171 doi: 10.1007/s11705-007-0031-7

摘要： The effects of MgO promoter on the physico-chemical properties and catalytic performance of Ni/AlO catalysts for the partial oxidation of methane to syngas were studied by means of BET, XRD, H-TPR, TEM and performance evaluation. It was found that the MgO promoter benefited from the uniformity of nickel species in the catalysts, inhibited the formation of NiAlO spinel and improved the interaction between nickel species and support. These results were related to the formation of NiO MgO solid solution and MgAlO spinel. Moreover, for the catalysts with a proper amount of MgO promoter, the nickel dispersiveness was enhanced, therefore making their catalytic performance in methane partial oxidation improved. However, the excessive MgO promoter exerted a negative effect on the catalytic performance. Meanwhile, the basicity of MgO promoted the reversed water gas shift reaction, which led to an increase in CO selectivity and a decrease in H2 selectivity. The suitable content of MgO promoter in Ni/AlO catalyst was ?7 wt-%.

关键词： excessive selectivity decrease dispersiveness physico-chemical

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Evaluation of the relative risk of stroke in patients with hypertension using cerebrovascular hemodynamic accumulative score

HUANG Jiuyi, WANG Guiqing, GUO Jiping, CAO Yifeng, WANG Yan, YANG Yongju, YU Xuehai

《医学前沿（英文）》 2007年第1卷第3期页码 274-278 doi: 10.1007/s11684-007-0052-0

摘要： The relative risk (RR) of stroke in patients with hypertension was evaluated by using synthetic index of cerebrovascular hemodynamics. A total of 7,371 patients with hypertension with ages ≥40 years were selected from a population-based cohort study of the risk factors for stroke. The data on the baseline investigation of risk factors, the determination of cerebrovascular hemodynamic parameters (CVHP), and stroke follow-up were analyzed. The RR of stroke in patients with hypertension was evaluated by CVHP scores. Univariate analysis indicated that hypertension, complicated by other risk factors, had significant statistical association with the onset of stroke. RRs for stroke when hypertension complicated with decrease of hemodynamic scores, heart disease, cigarette smoking and alcohol consumption were 4.93 (95%CI, 3.26–7.45), 1.90 (95%CI, 1.36–2.66), 1.99 (95%CI, 1.42–2.79) and 1.73 (95%CI, 1.19–2.53) respectively. In multivariate analysis, hemodynamic score, age, sex, cigarette smoking, family history of stroke and systolic blood pressure were selected by the Cox regression for inclusion in the final analysis. Among them, the RR of hemodynamic score was highest. The analysis of doseresponse relationships indicated that when the hemodynamic scores in patients with hypertension were lower than 75 points, the RR of stroke at 75, 60, 45, 30 and 15 points were 2.85, 4.43, 4.54, 5.40 and 9.88, respectively. The risk of stroke in patients with hypertension is closely asso ciated with hemodynamic impairment and the hemodynamic score may be used for quantitative evaluation of relative risks of stroke.

关键词： inclusion quantitative evaluation cerebrovascular relative decrease

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Hydrogen peroxide is correlated with browning in peach fruit stored at low temperature

Zhansheng DING, Shiping TIAN, Xianghong MENG, Yong XU,

《化学科学与工程前沿（英文）》 2009年第3卷第4期页码 363-374 doi: 10.1007/s11705-009-0246-x

摘要： The objective of this present research is to study the biological basis of browning in peach fruit during storage at low temperatures. After being immersed in 0 or 2mmol·L salicylic acid (SA) aqueous solution for 10min, peach fruit (Prunus persica L. cv. Hongtao) were stored at 10°C, 5°C or 0°C with or without shelf life at 25°C. During storage, the progress of browning, lipid per-oxidation, phenol content, activities of polyphenol oxidase (PPO, E.C. 1.14.18.1) and guaiacol peroxidase (POD, EC 1.11.1.7), redox state of ascorbate and glutathione, as well as the content, location and metabolism of hydrogen peroxide (HO) in the fruit were examined. The results indicated that a decrease in HO content was correlated with browning, whereas phenol content and activities of PPO and POD were not correlated with the change in HO content. Moreover, HO content was influenced by different responses of antioxidants at different storage conditions. It was concluded that the main effect of HO on browning was to regulate its appearance and development as a signal molecule, and lower HO content was beneficial to browning.

关键词： beneficial per-oxidation appearance decrease hydrogen peroxide

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节能优先能源战略的经济学讨论

周大地

《中国工程科学》 2011年第13卷第6期页码 11-18

摘要：

从我国面临科学发展和转变经济发展方式迫切需求出发，分析节能降耗的总体经济效益，以探讨实施积极的节能降耗目标的经济合理性。笔者对“十一五”期间节能降耗工作的总体经济效益进行了评估，用数据和事实肯定了“十一五”节能降耗的巨大经济效益；并分析了提高能效对我国“十二五”转变经济发展方式，支持长期可持续经济发展的宏观经济效果及其必要性和合理性。

关键词：能源战略节能降耗节能经济效益科学发展经济学

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Studies on catalytic reduction of nitrate in groundwater

GENG Bing, ZHU Yanfang, JIN Zhaohui, LI Tielong, KANG Haiyan, WANG Shuaima

《环境科学与工程前沿（英文）》 2007年第1卷第3期页码 357-361 doi: 10.1007/s11783-007-0061-x

摘要： Catalytic reduction of nitrate in groundwater by sodium formate over the catalyst was investigated. Pd-Cu/-AlO catalyst was prepared by impregnation and characterized by brunauer-emmett-teller (BET), inductive coupled plasma (ICP), X-ray diffraction (XRD), transmission electron microscopy (TEM) and energy dispersive X-ray (EDX). It was found that total nitrogen was effectively removed from the nitrate solution (100 mg/L) and the removal efficiency was 87%. The catalytic activity was affected by pH, catalyst amount used, concentration of sodium formate, and initial concentration of nitrate. As sodium formate was used as reductant, precise control in the initial pH was needed. Excessively high or low initial pH (7.0 or 3.0) reduced catalytic activity. At initial pH of 4.5, catalytic activity was enhanced by reducing the amount of catalyst, while concentrations of sodium formate increased with a considerable decrease in N selectivity. In which case, catalytic reduction followed the first order kinetics.

关键词： dispersive electron microscopy considerable decrease Catalytic reduction brunauer-emmett-teller

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Dilution rate and microstructure of TIG arc Ni-Al powder surfacing layer

SHAN Jiguo, DONG Wei, TAN Wenda, ZHANG Di, REN Jialie

《机械工程前沿（英文）》 2007年第2卷第1期页码 20-24 doi: 10.1007/s11465-007-0003-0

摘要： Surfacing beads are prepared by a direct current tungsten inert gas arc nickel-aluminum (Ni-Al) powder surfacing process. With the aim of controlling the dilution rate and obtaining surfacing beads rich in intermetallic compounds, the effects of surfacing parameters on geometric parameters, dilution rate, composition, and microstructure of the bead are investigated. An assistant cooler, which can potentially reduce the temperature of the base metal, is used in the surfacing process and its effect on dilution rate and microstructure is studied. The result indicates that with the surfacing parameter combination of low current and speed, the width and penetration of the bead decrease, reinforcement increases, and dilution rate drops markedly. With the reduction of the parameter combination, the intergranular phase ?-(Fe, Ni) is formed in the grain boundaries of Ni-Al intermetallic matrix instead of the intergranular phase ?-Fe, and large amount of intermetallics are obtained. With the use of an assistant cooler on a selected operation condition during the surfacing process, the reinforcement of the bead increases, penetration decreases, and dilution rate declines. The use of an assistant cooler helps obtain a surfacing bead composed of only intermetallics.

关键词： decrease Ni-Al surfacing parameter temperature surfacing process

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近20年能源结构调整使我国土壤多环芳烃浓度下降 Article

夏星辉, 刘亚男, 张真瑞, 席楠楠, 保嘉傲, 杨志峰

《工程（英文）》 2023年第21卷第2期页码 115-123 doi: 10.1016/j.eng.2021.11.023

摘要：

近几十年来，我国在快速发展和工业化的同时，在环境污染防治方面也做出了巨大努力。然而，这些全国性措施（如能源结构调整）对土壤中污染物浓度的影响尚未得到很好的量化。多环芳烃（PAHs）污染在全球范围内引发重要关注，且PAHs排放与能源结构有关。因此，我们推测我国能源结构的调整可能会降低土壤中PAHs的含量。为了验证这一假设，我们于2008 年和2019 年在北京54 个点位重复采集了土壤样品，分析了美国环境保护署（US EPA）提出的16 种优控PAHs 化合物（Σ₁₆PAHs）的浓度，并收集了过去20 年全国1704 个土壤采样点的数据。结果表明，我国Σ₁₆PAHs浓度沿城市-郊区-农村-背景点梯度下降，且Σ₁₆PAHs 浓度与区域总产值（GRP）有关，在GRP 较低时Σ₁₆PAHs 浓度随GRP 的增加而增加，随后在GRP 达到一定水平时趋于平稳。过去20 年，我国土壤Σ₁₆PAHs 的平均浓度呈下降趋势，其中北京土壤Σ₁₆PAHs的平均浓度从2008 年的22.7 μg⋅g^‒1总有机碳（TOC）显著下降到2019 年的10.0 μg⋅g^‒1 TOC。源识别分析推断，土壤PAHs浓度的下降趋势是由于我国煤炭、焦炭、部分油类消费量下降以及电力、天然气等清洁能源消费量上升所致。本研究例证了调整能源结构在降低土壤多环芳烃浓度和改善土壤环境质量中的重要作用。

关键词：多环芳烃土壤黑碳环境污染能源结构可持续发展

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穿越“环境高山”——论经济增长过程中环境负荷的上升与下降

陆钟武,毛建素

《中国工程科学》 2003年第5卷第12期页码 36-42

摘要：

把描绘发达国家经济增长过程中的环境负荷曲线比喻成“环境高山”。强调了发展中国家，尤其是中国，发展经济的正确之路是：从“环境高山”的半山腰穿过去，走新型工业化道路。推导了环境负荷与GDP之间的关系式，其中GDP年增长率g和单位GDP环境负荷年下降率t是两个关键变量。以一些国家和中国的一些省份为实例，分析了经济增长与能源消费量之间的关系。在不同的假设条件下，计算了2005，2010，2020年中国的环境负荷，并以能源消耗为例，做了进一步的说明。

关键词：环境高山” 环境负荷 GDP年增长率单位GDP环境负荷单位GDP环境负荷的年下降率