摘要：
To research the dynamic mechanical properties and road performances of flame retardant asphalt mortars and mixtures, four different asphalt mortars/mixtures were prepared: a reference group and three asphalt mortars/mixtures containing composite flame retardant materials (M-FRs) of different proportions. Temperature sweep, frequency sweep, repeated creep test, force ductility test and bending beam rheological test were carried out to research the dynamic mechanical properties of asphalt mortars containing M-FRs; wheel-tracking test, low-temperature bending test and freeze-thaw split test were used to study the road performances of asphalt mixtures containing M-FRs. The results show that high-temperature performances of the three flame retardant asphalt mortars improve greatly, while low-temperature cracking resistances decline. Both high-temperature performances and water stabilities of asphalt mixtures containing M-FRs are quite good and exceed the specification requirements. However, their low-temperature performances decline in different degrees. In summary, besides their good flame retardancy, the flame retardant asphalt mortars and mixtures also exhibit acceptable road performance.
摘要：
An analytical consideration has been made to explore the velocity, temperature and nanoparticle distributions and heat transfer characteristics associated with thermal dispersion and nanoparticle mechanical dispersion within a nanofluid-saturated homogeneous metal foam. A volume-averaging theory was rigorously applied to integrate locally a set of governing equations based on the modified Buongiorno model at the pore scale. Thus, a macroscopic set of volume-averaged governing equations were derived allowing interstitial heat transfer between the nanofluid and metal phases. Unknown terms were modelled mathematically to obtain a closed set of volume-averaged governing equations. Subsequently, a pore-scale analysis was carried out to find possible functional forms for describing thermal dispersion and nanoparticle mechanical dispersion in a nanofluid-saturated metal foam. Using the resulting set of volume-averaged governing equations, forced convective flows in nanofluid-saturated metal foams were analytically investigated for the steady-state case. Eventually, it has been predicted that an unconventionally high level of the heat transfer rate (about 80 times more than the case of base fluid convection without a metal foam) may be achieved by combination of metal foam and nanofluid.
期刊：
Journal of Chemistry,2015年2015:1-7 ISSN：2090-9063
通讯作者：
Lu, Haijun
作者机构：
[Lu, Haijun] Chinese Acad Sci, Inst Rock & Soil Mech, State Key Lab Geomech & Geotech Engn, Wuhan 430071, Peoples R China.;[Wang, Changhong; Lu, Haijun; Dong, Yiqie; Li, Jixiang] Wuhan Polytech Univ, Inst Poromech, Wuhan 430023, Peoples R China.
通讯机构：
[Lu, Haijun] C;Chinese Acad Sci, Inst Rock & Soil Mech, State Key Lab Geomech & Geotech Engn, Wuhan 430071, Peoples R China.
摘要：
The potential of clay containing 0 similar to 5% sewage sludge ash (SSA) is assessed for use as a landfill liner-soil material. Low temperature N-2 adsorption, batch adsorption, permeability, and unconfined compressive strength tests are performed to evaluate pore structure, adsorption capacity, hydraulic conductivity, and unconfined compressive strength of the clays. The pore size distribution of the modified clay containing SSA ismainly composed of micropores (< 2 nm) andmesopores (2 similar to 7 nm). With the increasing of SSA from 0% to 5%, the adsorption capacity of Zn(II) and Cu(II) to the clay increases 37% and 273%, respectively. The hydraulic conductivity of modified clay is from 3.62 x 10(-8) to 2.17 x 10(-8) cm/s. At SSA = 3%, the unconfined compressive strength of the clay reaches the maximum value of 601.1 kPa. After the clay containing SSA is contaminated by acid and alkali chemical solutions, the amount of mesopores and hydraulic conductivity increase. The adsorption capacity and unconfined compressive strength of contaminated clay decrease about 2 similar to 44% and 25.7 similar to 38.2%, respectively. The modified clay containing SSA can meet the adsorption and geotechnical requirement of landfill liners.
摘要：
The temperature dependency of the thermophysical properties of an alumina–water nanofluid and their effects on laminar forced-convective heat transfer enhancement in nanofluids have been investigated analytically in this study. Exact solutions have been obtained for hydrodynamically and thermally fully developed nanofluid flows in a tube subject to constant heat flux, with and without accounting for the temperature dependency of thermophysical properties. The solutions reveal that the anomalous heat transfer enhancement is possible, irrespective of the account of the temperature dependency of nanofluid thermophysical properties, such that the heat transfer rate exceeds the rate expected from the increase in the nanofluid thermal conductivity. A comparison between the solutions, with and without accounting for the temperature dependency of nanofluid thermophysical properties, indicates that the temperature dependency of thermophysical properties only reflects on the relative magnitude of the Nusselt number and its asymptotic value, and that it does not have any significant influence on the occurrence of anomalous heat transfer enhancement.
摘要：
Anti-Corrosion coatings are extensively applied in maintenance and vehicles used by transportation agencies, which have been used to protect a substrate by providing a barrier between the metal and its environment outside, especially in a chloride-laden environments. In order to provide adequate corrosion protection, the coatings must be uniform, well adhered, pore free and self-healing for applications where physical damage to the coating may occur. The aim of this review is to examine the state of the corrosion coatings for the protection of various metals/alloys commonly used in maintenance equipment and vehicles, and to identify cost effective, high-performance corrosion inhibitors that may contribute to the preservation of equipment assets. The focus is placed on the metallic corrosion induced or aggravated by chlorides at ambient temperature and pressure, and near neutral pH (6-8).
摘要：
The heat-moisture transport through the compacted clay was observed in laboratory. The hydraulic conductivity of cracked clay under wetting-drying cycles was also investigated. At the early phase of heating, the temperature of soil columns rose fast and moisture decreased dramatically; after this phase, the temperature rose at a lower speed and moisture loss stabilized gradually. The moisture content of compacted clay at 25 cm depth decayed to 0. The crack intensity factor (CIF) of compacted clay was 0.043 and 0.097; the crack depth was about 6.5 cm and 8.2 cm at 50 degrees C and 60 degrees C, respectively. The hydraulic conductivity of compacted clay was within 8.3 x 10(-7) to 1.5 x 10(-5) cm/s after four wetting-drying cycles. This value was 2 similar to 3 orders of magnitude higher than that of uncracked clay.
摘要：
Generalized Pattern Search Algorithm (GPSA) has rarely been investigated for structural health monitoring, but may have potential application in civil engineering, because it does not require any gradient information of the objective function. Meanwhile, indirect identification is an attractive concept that recognizes the bridge parameters by the vehicle responses. This paper proposes a theoretical indirect identification method based on optimization method, and the implementation is performed by the GPSA. Firstly, the GPSA theory is investigated, and a simple example is employed to describe the process of the algorithm. Secondly, a theoretical indirect identification method is proposed, based on the optimization method rather than the conventional transforms from time domain to frequency domain. The proposed method can identify the parameters of the vehicle–bridge system, including the bridge stiffness and the 1st frequency. Based on the optimization method, the feasibility and accuracy of GPSA are demonstrated with 0.06% of errors. The GPSA shows good robustness in the identifications with various noise levels, and the maximum error is about 3.30% and can be accepted for the engineering application even with a SNR 5 noise level. The computation time relies only on the function evaluation times, and is not positively related to the noise level. Thirdly, the performance of GPSA is compared with that of Genetic Algorithm (GA). The accuracy of GPSA and GA are approximately equivalent with various noise levels. Compared with GA, GPSA needs fewer iterations and much fewer evaluations, therefore is more efficient in the identification with an almost consistent accuracy with various noise levels.
期刊：
Journal of Transportation Engineering,2014年140(11) ISSN：0733-947X
通讯作者：
Shi, Xianming
作者机构：
[Shi, Xianming] Wuhan Polytech Univ, Sch Civil Engn & Architecture, Bozeman, MT 59717 USA.;[Akin, Michelle; Shi, Xianming; Fay, Laura; Veneziano, David A.] Montana State Univ, Western Transportat Inst, Bozeman, MT 59717 USA.;[Shi, Xianming] Montana State Univ, Dept Civil Engn, Bozeman, MT 59717 USA.;[Zhang, Yan; Jungwirth, Scott] Montana State Univ, Western Transportat Inst, Corros & Sustainable Infrastruct Lab, Bozeman, MT 59717 USA.;[Wright, Ron] Idaho Transportat Dept ITD, Boise, ID 83707 USA.
通讯机构：
[Shi, Xianming] W;Wuhan Polytech Univ, Sch Civil Engn & Architecture, POB 174250, Bozeman, MT 59717 USA.
摘要：
The use of chemicals and abrasives for highway winter maintenance operations is an essential strategy for ensuring a reasonably high level of service, yet the performance of such materials has to be balanced with their potential negative impacts on motor vehicles, transportation infrastructure, and the natural environment. In this context, this work presents a comprehensive and quantitative evaluation of snow and ice control chemicals currently used by various Idaho Transportation Department districts for highway maintenance operations, including rock salts (mainly solid sodium chloride), IceSlicer products (solid sodium chloride with trace amounts of other chlorides), and salt brines. The analysis has been enabled by the utilization of existing lab and field test data along with reasonable assumptions, in the effort to identify environmentally sustainable materials for winter highway operations. Despite its caveats, this case study is the first attempt to incorporate the most up-to-date information into a multicriteria decision making framework for the data-driven, holistic examination of various snow and ice control chemicals used by a maintenance agency. (C) 2014 American Society of Civil Engineers.
