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FREEZE/THAW PERFORMANCE OF CONCRETE uSING GRANuLATED RuBBER CRuMB

Journal of Green Building 2011年第1期6卷 83-92页

作者： A.Richardson K.Coventry u.dave J.Pienaar Northumbria university Newcastle upon TyneUK Nirma university India

This paper evaluates the properties and use of recycled rubber tyres in the form of rubber crumb as a freeze/thaw protection agent when used in *** scrap tyres in the form of rubber crumb in concrete could benefit the environment by contributing to the percentage of tyres used for a variety of recycling processes such as carpet underlay or tyre derived fuel,thus reducing disposal of tyres to landfill sites and the chemical usage of air entraining agents as a means of achieving freeze/thaw *** cubes of 100mm were produced from design mixes which have been classified as plain,air entrained and rubber crumb and subjected to freeze/thaw cycles at 5 days of *** was conducted in water to ensure full saturation of pores and maximum stress on the concrete *** rubber crumb and plain concrete mixes were compared against the freeze/thaw performance of that entrained with *** entrainment is known to protect against freeze/thaw *** crumb when used at a 0.5%addition by volume provided the optimum freeze/thaw protection whilst maintaining the maximum compressive *** research shows that rubber crumb was effective at providing freeze/thaw protection albeit with a reduced compressive strength when compared to air entrained *** practical constraints of the test program were time and freezer space so the test was limited to 50 freeze/thaw cycles,which was sufficient for conclusions to be *** paper contributes to the understanding of the effects of varying doses of rubber crumb in concrete when used as a freeze/thaw protection *** final compressive strength of the concrete mixes tested at freeze/thaw and non freeze/thaw conditions are *** compaction of concrete is raised as an area of concern with regard to rubber particle separation within the plastic phase of the concrete’s life.

关键词： rubber crumb concrete freeze/thaw protection sustainability recycled tyres

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A note on Optimal weights and variable selections for multivariate survival data

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Science China Mathematics 2009年第6期52卷 1131-1133页

作者： Zhao Sihai dave Department of Biostatistics Harvard School of Public Health and Dana-Farber Cancer Institute Boston MA 02115 USA

Fan et al. are to be congratulated for this important contribution to the analysis of multivariate failure time data. They have provided three regression parameter estimators for multiple covariates in the marginal ha... 详细信息

关键词： weights multivariate estimating variance marginal hazard likelihood asymptotically estimates choose

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Mantle avalanches in a Venus-like stagnant lid planet

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Earth and Planetary Physics 2024年第5期8卷 686-702页

作者： Madeleine C.Kerr dave R.Stegman Institute of Geophysics and Planetary Physics Scripps Institution of OceanographyUniversity of CaliforniaSan DiegoLa JollaCAUSA

Stagnant lid planets are characterized by a globe-encircling,conducting lid that is thick and strong,which leads to reduced global surface heat ***,the mantles of such planets can have warmer interiors than Earth,and interestingly,a pyrolitic mantle composition under warmer conditions is predicted to have a distinctly different mantle transition zone compared to the present-day Earth(Hirose,2002;Stixrude and Lithgow-Bertelloni,2011;Ichikawa et al.,2014;Dannberg et al,2022).Instead of olivine primarily transforming into its higher-pressure polymorphs such as wadsleyite and then ringwoodite,at pressures corresponding to 410 km and 520 km depth in Earth,respectively,it instead transforms into a mineral assemblage of wadsleyite,majorite,and ferropericlase(WMF),and then to majorite+ferropericlase(MF),before finally transforming into bridgmanite at pressures corresponding to 660 km depth in Earth(Stixrude and Lithgow-Bertelloni,2011;Ichikawa et al.,2014).Convective motions in stagnant lid planets are dominated by small-scale instabilities(cold drips)forming within the mobile rheological sublayer under the rigid *** ASPECT and a thermodynamic model of a pyrolitic mantle composition generated by HeFESTo,we show that under certain conditions,the small drips can pond atop the WMF-MF mineral phase *** barrier to convective flow arises from the WMF mineral phase assemblage having an effective negative thermal expansivity(Stixrude and Lithgow-Bertelloni,2022).Although large-scale downwellings that typically occur within mobile lid planets are able to pass through the WMF zone without difficulty(Dannberg et al.,2022;Li RP et al.,2024),the smaller and less negatively buoyant nature of downwelling drips in stagnant lid planets are more susceptible to these effects,which leads to an ephemeral layering of the *** numerical models show that in stagnant lid planets with mantle potential temperatures that exceed 1900 K,the smaller,cold drips from t

关键词： Venus mantle avalanches numerical modelling phase transitions

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Ensemble-based uncertainty quantification for coordination and control of thermostatically controlled loads

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Journal of Control and Decision 2018年第2期5卷 148-168页

作者： Weixuan Li Jianming Lian dave Engel Hong Wang Pacific Northwest National Laboratory RichlandWAUSA

This work investigates an uncertainty quantification(uQ)framework that analyses the uncertainty involved in modelling control systems to improve control strategy *** framework involves solving four problems:identifying uncertain parameters,propagating uncertainty to the quantity of interest,data assimilation and making decisions under quantified uncertainties.A specific group of uQ approaches,known as the ensemble-based methods,are adopted to solve these *** uQ framework is applied to coordinating a group of thermostatically controlled loads,which relies on simulating a second-order equivalent thermal parameter model with some uncertain *** this uncertainty affects the prediction and the control of total power is *** study shows that uncertainty can be effectively reduced using the measurement of air ***,the control objective is achieved fairly accurately with a quantification of the uncertainty.

关键词： uncertainty quantification ensemble-based method thermostatically controlled loads transactive control smart grid

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Functional and physiochemical properties of protein isolates from different body parts of North Atlantic sea cucumber (Cucumaria frondosa)

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Food Bioscience 2023年第2期52卷 1379-1388页

作者： Tharindu R.L.Senadheera Abul Hossain Deepika dave Fereidoon Shahidi Department of Biochemistry Memorial University of NewfoundlandSt.John’sNLA1C 5S7Canada Marine Bioprocessing Facility Centre of Aquaculture and Seafood DevelopmentFisheries and Marine InstituteMemorial University of NewfoundlandSt.John’sNLA1C 5R3Canada

Sea cucumbers are a good source of proteins and essential amino *** this study,protein isolates were recovered from North Atlantic sea cucumber(Cucumaria frondosa)body wall(BWI)and processing by-products,including flower(FLI)and internal organs(INI),using the pH-shift *** properties of protein isolates were investigated and compared with those of soy protein isolates(SPI).All protein isolates exhibited a typical u-shaped solubility curve showing a minimum solubility at their isoelectric ***,emulsification and foaming properties of the sea cucumber protein isolates were also pH-dependent and corresponded with their *** highest water holding capacity was observed in FLI,whereas SPI showed the lowest oil holding capacity among all tested protein *** cucumber protein isolates exhibited significantly higher(purface hydrophobicity and relatively lower sulfhydryl(SH)group and disulfide(SS)bonds compared to *** addition,Fourier transform infrared(FTIR)spectra of sea cucumber protein isolates exhibited unique absorption peaks related to their secondary *** acid profiles of sea cucumber protein isolates revealed that they could be used as rich and complete sources of essential amino *** findings suggest that Atlantic sea cucumber protein isolates could serve as functional food ingredients.

关键词： Sea cucumber Cucumaria frondosa Protein isolates Functional properties

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库岸有限厚度粉质黏土冲蚀演化规律及预测

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水科学进展 2023年第6期34卷 938-947页

作者：陈勇张书石 CHAN dave 三峡大学三峡库区地质灾害教育部重点实验室湖北宜昌443002 Department of Civil and Environmental Engineering University of AlbertaEdmontonAB T6G 2W2Canada

土体冲蚀流失是塌岸发展和库岸再造的重要诱发因素。为准确预测水流作用下岸坡土体流失进程,自主研制了能够实时精确量测土样质量变化的新型冲蚀试验装置,开展三峡库岸粉质黏土冲刷起动和冲蚀进程试验,分析有限厚度土体冲蚀演化规律和... 详细信息

土体冲蚀流失是塌岸发展和库岸再造的重要诱发因素。为准确预测水流作用下岸坡土体流失进程,自主研制了能够实时精确量测土样质量变化的新型冲蚀试验装置,开展三峡库岸粉质黏土冲刷起动和冲蚀进程试验,分析有限厚度土体冲蚀演化规律和影响机制,并建立预测模型。结果表明:有限厚度土体的总冲蚀量随时间增加但增速逐渐趋缓,冲蚀速率逐渐衰减,且冲蚀速率及其衰减程度均与孔隙比或流速成正比;将反映密实度的孔隙比和反映剪切力的水流速度嵌入预测模型能较好地拟合粉质黏土冲蚀演化进程曲线。建立的有限厚度土体冲蚀进程预测模型,为水流冲刷作用下岸坡形态变化趋势预测研究提供参考。

关键词：冲蚀试验有限厚度冲蚀比冲蚀速率预测模型

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Assessing support alternatives for longwall gateroads subject to changing stress

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International Journal of Mining Science and Technology 2021年第1期31卷 103-110页

作者： Gabriel S.Esterhuizen I.Berk Tulu.dave F.Gearhart Heather Dougherty Mark Van Dyke National Institute for Occupational Safety and Health Pittsburgh Mining Research DivisionPittsburghPA 15236USA West Virginia university MorgantownWV 26506USA

Longwall gateroad entries are subject to changing horizontal and vertical stress induced by redistribution of loads around the extracted *** stress changes can result in significant deformation of the entries that may include roof sag,rib dilation,and floor *** operators install different types of supports to control the ground response and maintain safe access and ventilation of the longwall *** paper describes recent research aimed at quantifying the effect of longwall-induced stress changes on ground stability and using the information to assess support *** research included monitoring of ground and support interaction at several operating longwall mines in the u.S.,analysis and calibration of numerical models that adequately represent the bedded rock mass,and observation of the support systems and their response to changes in *** models were then used to investigate the impact of geology and stress conditions on ground deformation and support response for various depths of cover and geologic *** research results were summarized in two regression equations that can be used to estimate the likely roof deformation and height of roof yield due to longwall-induced stress *** information is then used to assess the ability of support systems to maintain the stability of the *** application of the method is demonstrated with a retrospective analysis of the support performance at an operating longwall mine that experienced a headgate roof *** method is shown to produce realistic estimates of gateroad entry stability and support performance,allowing alternative support systems to be assessed during the design and planning stage of longwall operations.

关键词： Longwall Gateroad Support design Coal Standing support

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China Through the Eyes of a u.S. Businessman

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China Today 1994年第1期43卷 31-32页

作者： $$$$dave Bruels

Although the Msisippi is nearly halfway across the planet from the Yellow River in China,unita Blackwell,now in her 60s,has helped to build,through 20 years of hard work,a special friendship bridge between these two *... 详细信息

关键词： Businessman China Through the Eyes of a u.S

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Effect of stress sensitivity on displacement efficiency in CO_2 flooding for fractured low permeability reservoirs

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Petroleum Science 2009年第3期6卷 277-283页

作者： Wang Rui Yue Xiang＇an Zhao Renbao Yan Pingxiang dave Freeman Key Laboratory of Petroleum Engineering Ministry of Education China University of Petroleum Beijing 102249 China SINOPEC Exploration ＆ Production Research Institute Beijing 100083 China China Power Complete Equipment Co. Ltd. Beijing 100011 China Edwy R. Brown Department of Petroleum Engineering Marietta College U.S.A.

Carbon dioxide flooding is an effective means of enhanced oil recovery for low permeability reservoirs. If fractures are present in the reservoir, CO2 may flow along the fractures, resulting in low gas displacement efficiency. Reservoir pore pressure will fluctuate to some extent during a CO2 flood, causing a change in effective confining pressure. The result is rock deformation and a reduction in permeability with the reduction in fracture permeability, causing increased flow resistance in the fracture space. Simultaneously, gas cross flowing along the fractures is partially restrained. In this work, the effect of stress changes on permeability was studied through a series of flow experiments. The change in the flowrate distribution in a matrix block and contained fracture with an increase in effective pressure were analyzed. The results lead to an implicit comparison which shows that permeability of fractured core decreases sharply with an increase in effective confining pressure. The fracture flowrate ratio declines and the matrix flowrate ratio increases. Fracture flow will partially divert to the matrix block with the increase in effective confining pressure, improving gas displacement efficiency.

关键词： Stress sensitivity flowrate distribution matrix fracture CO2 flooding displacement efficiency

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正交异性钢桥面板典型节点热点应力分析

正交异性钢桥面板典型节点热点应力分析

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作者： Dibu.dave Mbako 上海交通大学

学位级别：硕士

由桥面板,纵肋和横梁组成的正交异性钢桥面板,由于其特有的特性,引起了许多桥梁工程师,非常轻。正交异性钢甲板的金属结构特别适用于重量是设计的关键参数,如大型和非常大的甲板或活动跨度。然而,交通繁忙的增加,因为桥面被车轮荷载直... 详细信息

由桥面板,纵肋和横梁组成的正交异性钢桥面板,由于其特有的特性,引起了许多桥梁工程师,非常轻。正交异性钢甲板的金属结构特别适用于重量是设计的关键参数,如大型和非常大的甲板或活动跨度。然而,交通繁忙的增加,因为桥面被车轮荷载直接加载,并且由于焊接引起的残余应力的结果倾向于使正交异性甲板疲劳行为成为更为关键的问题。因此,深入研究正交异性钢桥面板的疲劳裂缝是至关重要的。在这些疲劳裂纹中,在肋对甲(RD)接头周围出现裂纹,而纵桁对甲板(SD)是最关键的,因为接头疲劳裂纹会导致顶面损坏。本研究的目的是研究SD和RD接头的热点应力。主要研究内容如下:(1)采用实体单元和壳单元构建正交异性钢甲板结构的有限元模型并进行分析。总的来说,本文研究了整个桥梁结构的两种焊接连接方式:纵梁到甲板(SD)和肋骨到甲板(RD)。这些连接是可能发生疲劳的区域。(2)共10个试件,包括4个SD接头和6个RD接头。中心和偏心负载被认为是静态负载的一部分。通过外推法测量焊趾附近的应力,得到焊趾热点应力。(3)根据实验测试结果和有限元分析结果,比较了解得更好,并对两种结果的关系进行了研究。在80%焊缝渗透到u形肋中时,甲板的表面应力显着大于接缝附近的肋的表面应力。分析模型显示了与有限元模型的良好符合性。

关键词：正交异性钢甲板压力分布铁路桥热点压力有限元法

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