Predicting the International Roughness Index of JPCP and CRCP Rigid Pavement:A Random Forest(RF)Model Hybridized with Modified Beetle Antennae Search(MBAS)for Higher Accuracy

To improve the prediction accuracy of the International Roughness Index(IRI)of Jointed PlainConcrete Pavements(JPCP)and Continuously Reinforced Concrete Pavements(CRCP),a machine learning approach is developed in this study for the modelling,combining an improved Beetle Antennae Search(MBAS)algorithm and Random Forest(RF)model.The 10-fold cross-validation was applied to verify the reliability and accuracy of the model proposed in this study.The importance scores of all input variables on the IRI of JPCP and CRCP were analysed as well.The results by the comparative analysis showed the prediction accuracy of the IRI of the newly developed MBAS and RF hybrid machine learning model(RF-MBAS)in this study is higher,indicated by the RMSE and R values of 0.2732 and 0.9476 for the JPCP as well as the RMSE and R values of 0.1863 and 0.9182 for the CRCP.The accuracy of this obtained result far exceeds that of the IRI prediction model used in the traditional Mechanistic-Empirical Pavement Design Guide(MEPDG),indicating the great potential of this developed model.The importance analysis showed that the IRI of JPCP and CRCP was proportional to the corresponding input variables in this study,including the total joint faulting cumulated per KM(TFAULT),percent subgrade material passing the 0.075-mm Sieve(P_(200))and pavement surface area with flexible and rigid patching(all Severities)(PATCH)which scored higher.

Effects of Curing Systems on Properties of High Volume Fine Mineral Powder RPC and Appearance of Hydrates

The effects of different curing systems on the properties of high volume fine mineral powder RPC (reactive powder concrete) and the appearances of hydrates were studied. The experimental results show that dry-heating curing promotes the development of pozzolanic reactivity of fine mineral powder; due to low cement content, 0.20 water-bind ratio and high reactive fine mineral powder content, the strength of RPC increases by around 200% after steam curing and subsequent dry-heating curing. Scanning electron microscopy and energy spectrum diagram showed that: after the high volume fine mineral powder RPC with 0.16 water-bind ratio underwent steam curing and dry-heating curing, there was no significant change in the appearance of hydrates; after the RPC with 0.20 water-bind ratio, the cement content of 150 kg/m3 and more steel slag powder underwent dry-heating curing, there was a certain change in the appearance of C-S-H, the structure of gel was more compact and was uniformly distributed, and the Ca/Si of C-S-H gel decreased from 1.41 to around 1.20.

Durability and Micro-structure of Reactive Powder Concrete

Durability of traditional reactive powder concrete (RPC) with rich cement and high volume of fly-ash reactive powder concrete (FRPC ) were studied. The X-diffraction and scanning electron microscope (SEM) measurement was imployed to analyze the microstructure. The results show that both types of RPC have higher compressive strength, less volume shrinkage ratio and better carbonation-, chloride-, freezing-resistances than the conventional concrete. The results of X-diffraction indicate that they basically have C-S-H as the main composition without Ca(OH)2 crystal and ettringite. SEM results show that hydration products of FRPC is mainly Ⅲ-C-S-H which is piled up closely like densely arranged stone body and it has very compacted structure, in addition, Ca/Si ratio of C-S-H gel is lower than 1.5.

Creep characteristic simulation of deep soft rock roadway and long-term mechanical analysis of lining support

By the generalized Kelvin creep model,rheological characteristics of deep softrock and long-term mechanical behaviors of support structures were simulated.Mechanicaldeformation characteristics of support structures under different lining circumstanceswere also analyzed on the basis of deducing the relationship between the generalizedKelvin creep model and implicit creep equations in ANSYS FEM software.The resultsshow that high stress of deep tunnels is the main factor in creep damage;the surroundingrock's deformation binding effect due to lining increases as the thickness increases but theeffect becomes very weak when it increases to a certain value;contact pressure on thelining decreases as its thickness decreases.

Research on inversion high mining pressure distribution and technology of preventing dynamic disasters by MS monitoring in longwall face

Under two rock strata combination conditions,over 10,000 microseismic eventswere received with microseismic location monitoring technology which possessed by theauthor's studying team,used in fully mechanized coal face of Huafeng Mine of XinwenCoal Mining Group Co.,Shandong Province.On the basis of the achievement of the locationresults,the conclusions were drawn as follows:On the basis of the achievement of 3Dstrata fracturing situation and the section plane of microseimic events in different areas,the relationship between spatial structure of overlying strata and mining pressure field wasfound,and we might describe distribution range of dynamic pressure of advance pressureand lateral stress around long face,and range of structure ad-tivation.Quantitative guidanceto prevent dynamic disasters was provided.The practice in coal mine got a effectiveresults.According to the FLAC3D soft numerical simulation of diameter drilling hole (thediameter is 300 mm) to relieve pressure in specified geological condition in Huafeng Mine,the right distance of two dirlls is 2.5 m and the right depth is 12 m.The research pro-videdbasic guiding and practical experiences for the underground microseismic monitoring anddisaster prevention in side slopes or tunnels engineering.

Form and Mechanism of Sulfate Attack on Cement-based Material Made of Limestone Powder at Low Water-binder Ratio under Low Temperature Conditions

The development of strength and the form of attack of cement-based material made of limestone powder at low water-binder ratio under low-temperature sulfate environment were studied. The results indicate that when water-binder ratio is lower than 0.40, the cement-based material with limestone powder has insignificant change in appearance after being soaked in 10% magnesium sulfate solution at low temperature for 120 d, and has significant change in appearance after being soaked at the age of 200 d. Expansion damage and exfoliation occur on the surface of concrete test cube at different levels. When limestone powder accounts for about 28 percent of cementitious material, with the decrease of water-binder ratio, the compressive strength loss has gradually decreased after the material is soaked in the magnesium sulfate solution at low temperature at the age of 200 d. After the specimen with the water-binder ratio of less than 0.4 and the limestone powder volume of greater than 20% is soaked in 10% magnesium sulfate solution at low temperature at the age of 200 d, gypsum attack-led destruction is caused to the concrete test cube, without thaumasite sulfate attack.

Hydrogen producting characteristics by a novel strain of bacteria-ethanoligenens sp. B49

The objective of this work is to investigate the fermentation capacity and metabolic characteristics of a novel strain of bacteria B49 isolated from anaerobic activated sludge. The examination was conducted in batch culture at 35 ℃. The results showed that the carbon flow gave priority to the production of ethanol, and yield of ethanol is always greater than that of acetic acid. The hydrogen and ethanol occurred simultaneously. The exponential phase of the B49's cell growth was from 12 to 22 h. Evolution of hydrogen appeared to start after the exponential phase of cell growth and reach maximum production at the early stationary phase. The rate of hydrogen production reached a maximum of 16.8 mL/h, and the percentage of hydrogen gas in the headspace of serum bottle obtained a maximum of 41 % at 22 h. The B49 was able to grow using molasses as substrate for cell growth. When the molasses was used as substrate, maximum yield of hydrogen was obtained 2460 mL/L culture at 2 % (V/V) of molasses. The hydrogen yield was increased to 3060 mL/L culture after addition of 0.5 g/L of yeast extract in the molasses medium and the yield of hydrogen was increased by 24.4%.

基于各向异性测度的路面三维图像裂缝识别

为准确而完整地识别路面裂缝,提出了基于1 mm/像素的路面三维图像裂缝自动识别算法.该算法主要包括各向异性测度计算与自适应优化阈值分割、深度验证和多分辨率去噪处理3个部分.首先,针对路面图像像素特征,基于0°、45°、90°和135°四个方向的线性邻域的均值和标准差计算每个像素的各向异性测度(表征方向性的强弱),并应用最大类间方差法确定最优阈值,将路面图像分为强方向性和弱方向性像素两类;其次,根据半径为d的正方形邻域深度均值设定阈值,用方向性强且深度低于或等于该阈值的像素形成初步的裂缝图像;最后,将裂缝图像划分为多个子块,设计去噪模板对裂缝图像进行滑动窗口去噪处理,获得最终裂缝图像.基于166幅含有各类裂缝的三维路面图像(2 048×2 048像素)进行测试分析,结果显示,本文算法获得了较高的准确率(均值91.57%)和召回率(均值81.29%),最终以84.26%的F1均值优于种子识别算法(F1均值69.19%)、Canny边缘检测(F1均值8.15%)和OTSU分割(F1均值5.11%).

基于海量车辆轨迹数据的机动车驾驶员驾驶行为评价（英文）

基于监控数据及车辆总线数据的营运车驾驶行为评价研究方法已相对成熟,但难以推广至私家车,针对自然驾驶试验样本容量小、设备昂贵的缺点,提出了一种基于海量秒级GPS导航数据的驾驶行为评价方法.运用自动编码机对数据进行降噪处理,结合行车动力学、SOM自组织映射分类等方法给出超速、急变速、频繁变道、急转弯等行为的判定方法及阈值,计算不同驾驶特性驾驶员及危险驾驶行为比例.在此基础上,分析得到深圳市机动车驾驶员驾驶行为时空分布特征、典型通道驾驶行为特征,并选取典型道路进行事故多发段与正常段的驾驶行为对比.结果表明,深圳危险驾驶行为以频繁变道和超速为主,16.1%的驾驶员驾驶行为偏冒进,原特区外相对原特区内危险驾驶行为比例更高,危险驾驶行为与事故密度呈高度相关.

环境因素对降解型生物膜形成的影响

采用改良微孔板法,考察p H、温度、培养时间和目标污染物浓度4个环境因子对3株氮杂环芳烃降解菌成膜的影响。结果表明,p H、温度、培养时间对生物膜的形成影响显著,且各降解菌的最佳成膜条件分别为：BC026成膜的最适p H为7,最适温度为35℃,培养时间为36小时;BW001成膜的最适p H为8,最适温度为35℃,培养时间为48小时;BW004成膜的最适p H为7～9,最适温度为40℃,培养时间为36小时。在0～1600 mg/L的目标污染物浓度内,目标污染物对生物膜形成的影响不显著。

水工钢闸门轮轨接触强度的安定算法分析

现行规范中,水工钢闸门轮轨接触强度设计准则凭经验和试验结果给出,而缺乏基于力学分析所建立的理论依据,甚至该准则在应用中存有争议。基于安定极限荷载下限理论探讨轮轨的接触强度问题,建立了自循环—优化安定分析算法,并据其对90个不同状态下的轮轨接触强度进行数值实验分析。结果表明:滚轮与轨道的最大赫兹接触应力与材料屈服强度的比值,并非为通常认为的唯一确定值,而是会受到材料屈服强度、切线模量系数、轮缘宽度和滚轮直径等多因素的影响,其中材料屈服强度的影响最大。这一发现说明规范中取这一比值为定值具有一定的局限性。虽然对于轮压较小、材料屈服强度相对较低的小型水利水电工程,规范规定是安全的;但对于大型水利水电工程,由于轮压较大,滚轮与轨道所用材料屈服强度相对较高,规范的规定偏于不安全。该研究为进一步探讨综合多因素、更具科学性的水工钢闸门轮轨接触强度设计准则,提供了基本力学方面的理论与方法支持。

Advanced Machine Learning Methods for Prediction of Blast-Induced Flyrock Using Hybrid SVR Methods

Blasting in surface mines aims to fragment rock masses to a proper size.However,flyrock is an undesirable effect of blasting that can result in human injuries.In this study,support vector regression(SVR)is combined with four algorithms:gravitational search algorithm(GSA),biogeography-based optimization(BBO),ant colony optimization(ACO),and whale optimization algorithm(WOA)for predicting flyrock in two surface mines in Iran.Additionally,three other methods,including artificial neural network(ANN),kernel extreme learning machine(KELM),and general regression neural network(GRNN),are employed,and their performances are compared to those of four hybrid SVR models.After modeling,the measured and predicted flyrock values are validated with some performance indices,such as root mean squared error(RMSE).The results revealed that the SVR-WOA model has the most optimal accuracy,with an RMSE of 7.218,while the RMSEs of the KELM,GRNN,SVR-GSA,ANN,SVR-BBO,and SVR-ACO models are 10.668,10.867,15.305,15.661,16.239,and 18.228,respectively.Therefore,combining WOA and SVR can be a valuable tool for accurately predicting flyrock distance in surface mines.

多株吡啶高效降解菌的降解性能与生物膜形成特性的研究

以吡啶为目标污染物,考察从焦化废水处理系统中分离的12株高效吡啶降解菌对吡啶的降解性能和生物膜形成特性,以期为在废水处理系统中构建降解型生物膜提供理论参考。结果表明:12株菌都具有较高的吡啶降解活性,其中代表性菌株Pseudomonas sp.ZX01和Arthrobacter sp.ZX07降解吡啶的最适温度是35°C,最适pH是7.0,在初始吡啶浓度为100~2000 mg/L的范围内,降解率均达到100%。不同菌株的生物膜形成能力差异明显,胞外蛋白分泌量、胞外多糖分泌量和由鞭毛参与的游动能力与各株菌的生物膜形成能力之间存在显著的正相关关系。

流动室系统中含氮杂环化合物降解菌的生物膜形成特征研究

采用流动室(Flow Cell)生物膜发生装置和激光共聚焦显微镜观察技术,揭示不同环境条件下含氮杂环化合物(nitrogenous heterocyclic compounds,NHCs)降解菌的生物膜形成特征。结果表明,增加初始接种菌液浓度并延长初始黏附时间,有利于吡啶降解菌在基质表面的黏附和生物膜形成;降低培养基流速,细菌生物膜更加均质化且形成水通道结构;不同条件下的生物膜都存在内层活细胞比例较低,外层活细胞比例较高的规律。此外,还发现相对于单一菌株,混合菌株在生物膜厚度、基质覆盖率与活细胞比例上都更具优势。目标NHC浓度对喹啉降解菌生物膜的形态和活性也有明显的影响:低浓度下降解菌团聚结构分布较零散,但具有较大的体积;高浓度下降解菌团聚结构明显变小,在基质表面的分布则更均匀;低浓度下生物膜的活细胞比例显著高于高浓度下的生物膜。

Application of AERMOD on near future air quality simulation under the latest national emission control policy of China: A case study on an industrial city

Air quality model can be an adequate tool for future air quality prediction, also atmospheric observations supporting and emission control strategies responders. The influence of emission control policy (emission reduction targets in the national "China's 12th Five-Year Plan (2011-2015)") on the air quality in the near future over an important industrial city of China, Xuanwei in Yunnan Province, was studied by applying the AERMOD modeling system. First, our analysis demonstrated that the AERMOD modeling system could be used in the air quality simulation in the near future for SO2 and NOx under average meteorology but not for PM10. Second, after evaluating the simulation results in 2008 and 2015, ambient concentration of SO2, NOx and PM10 (only 2008) were all centered in the middle of simulation area where the emission sources concentrated, and it is probably because the air pollutions were source oriented. Last but not least, a better air quality condition will happen under the hypothesis that the average meteorological data can be used in near future simulation. However, there are still heavy polluted areas where ambient concentrations will exceed the air quality standard in near future. In spatial allocation, reduction effect of SO2 is more significant than NOx in 2015 as the contribution of SO2 from industry is more than NOx. These results inspired the regulatory applications of AERMOD modeling system in evaluating environmental pollutant control

SEEPAGE ABILITY OF HIGH-PRESSURE HOT COMPOSITE FOAM IN POROUS MEDIA

The technology of hot composite foam displacement refers to the injection of high-temperature flue gas and foaming and stabilizing agent into wells with a certain concentration,and after meeting the formation water,a composite foam system is formed in the reservoir.This foam displacement technology involves thermal function and so is related to nitrogen,carbon dioxide and foam flooding characteristics.After analyzing seepage flow law of hot composite foam system,seepage flow experiment of composite foam under high pressure was conducted,and seepage flow ability of hot composite foam in porous media was investigated.In the experiment,surfactant HY-3 was chosen as the foaming agent and hot flue gas was chosen as the foaming gas,and high-pressure hot foaming apparatus was employed in experiments.The experimental results indicate that the surfactant HY-3 could form stable foam in porous media,and the foam has strong ability of plugging.It is concluded that the sealing performance of foam is improved with increasing permeability and resistance coefficient and with incresing injection rate and foam strength.After foam injection,sealing characteristics of heterogeneous cores is better than that of homogeneous cores.The foam pressure has a process of transmission in porous media.In this process,with the increase of injection volume,pressure from the inlet to the outlet increases gradually,which indicates that stable foam has been formed inside the core.

A multi-objective design method for seismic retrofitting of existing reinforced concrete frames using pin-supported rocking walls

Over the past several decades,a variety of technical ways have been developed in seismic retrofitting of existing reinforced concrete frames(RFs).Among them,pin-supported rocking walls(PWs)have received much attentions to researchers recently.However,it is still a challenge that how to determine the stiffness demand of PWs and assign the value of the drift concentration factor(DCF)for entire systems rationally and efficiently.In this paper,a design method has been exploited for seismic retrofitting of existing RFs using PWs(RF-PWs)via a multi-objective evolutionary algorithm.Then,the method has been investigated and verified through a practical project.Finally,a parametric analysis was executed to exhibit the strengths and working mechanism of the multi-objective design method.To sum up,the findings of this investigation show that the method furnished in this paper is feasible,functional and can provide adequate information for determining the stiffness demand and the value of the DCFfor PWs.Furthermore,it can be applied for the preliminary design of these kinds of structures.