A novel strategy for quantitative analysis of soil pH via laser-induced breakdown spectroscopy coupled with random forest

pH is one of the significant properties of soil,and is closely related to the decomposition of soil organic matter,anion-cation balance,growth of plants and many other soil processes.In the present work,laser-induced breakdown spectroscopy(LIBS) technique coupled with random forest(RF) was proposed to quantify the pH of soil.First,LIBS spectra of soil was collected,and some common elements in soil were identified based on the National Institute of Science and Technology database.Then,in order to obtain a better predictive result,the influence of different input variables(full spectrum,different spectral ranges,the intensity of characteristic bands and characteristic lines) on the predictive performance of RF calibration model was explored with the evaluation indicators of root mean square error(RMSE) and coefficient of determination(R2),the characteristic bands of four elements(AI,Ca,Mg and Si) were determined as the optimal input variables.Finally,the predictive performance of RF calibration model was compared with partial least squares calibration model with the optimal input variables and model parameters,and RF calibration model showed a better predictive performance,and the four evaluation indicators of R_p~2,RMSEP,mean absolute error and mean relative error were 0.9687,0.1285,0.1114 and 0.0136,respectively.It indicates that LIBS technique coupled with RF algorithm is an effective method for pH determination of soil.     

Oil Demand and Stocks

Current data of world oil demand. This includes international bunkers and refinery fuel. Updated on a monthly basis. Current data of oil demand from counties such as Canada, the United States of America, Japan, OECD Europe, Belgium, France, Germany, Italy, Netherlands, Spain, Sweden, the United Kingdom, Australia, Mexico, Republic of Korea, and Turkey. Updated on a monthly basis. Current data for crude oil and refined product stocks in Canada, Chile, Mexico, the United States (Western Hemisphere), France, Germany, Italy, Netherlands, Spain, the United Kingdom and Other Europe (Europe), Japan, Republic of Korea, Other Pacific (Asia-Pacific), and Total OECD (Table 12.1) Current data for refined product stocks in the OECD Western Hemisphere, OECD Europe, OECD Asia-Pacific and Total OECD. Products include gasoline, diesel and gasoil, and heavy fuel oil. Updated on a monthly basis (Table 12.2).     

重金属污染土壤回转窑协同处置和资源化利用

在中国，土壤中的重金属污染问题形势严峻，本文探索了一条采用先将重金属污染土壤中铅、镉、铜、锌固定再利用回转窑协同处置并资源化利用的技术途径。实验发现：添加适量的凹土及稳定化试剂并经稳定化处理以后，可以实现污染土壤由危险废物向一般固废的转变；进一步将稳定化处理后的土壤采用回转窑深度加工、能生产得到安全指标和产品性能合格的陶粒。经过优化实验方案后的结果显示，在铅、镉、铜、锌等重金属初始含量（上限）为2280mg/kg、592mg/kg、2000mg/kg、93400mg/kg的污染土壤添加4%的凹土（质量分数）及其他辅助材料后稳定化48h，上述重金属的可溶态检出量分别降低了50%、66%、59%、52%，经治理后的土壤可以转变为一般固废。用这种固定化处理后的土壤可以生产出合格的陶粒，而且在陶粒生产过程中逸散排放的铅、镉含量均低于大气污染物排放限制要求。     

Optimum lateral extent of soil domain for dynamic SSI analysis of RC framed buildings on pile foundations

This article describes a novel approach for deciding optimal horizontal extent of soil domain to be used for finite element based numerical dynamic soil structure interaction (SSI) studies. SSI model for a 12 storied building frame, supported on pile foundation-soil system, is developed in the finite element based software framework, OpenSEES. Three different structure-foundation configurations are analyzed under different ground motion characteristics. Lateral extent of soil domain, along with the soil properties, were varied exhaustively for a particular structural configuration. Based on the reduction in the variation of acceleration response at different locations in the SSI system (quantified by normalized root mean square error, NRMSE), the optimum lateral extent of the soil domain is prescribed for various structural widths, soil types and peak ground acceleration levels of ground motion. Compared to the past studies, error estimation analysis shows that the relationships prescribed in the present study are credible and more inclusive of the various factors that influence SSI. These relationships can be readily applied for deciding upon the lateral extent of the soil domain for conducting precise SSI analysis with reduced computational time.     

New pseudo-dynamic analysis of two-layered cohesive-friction soil slope and its numerical validation

Natural slopes consist of non-homogeneous soil profiles with distinct characteristics from slopes made of homogeneous soil. In this study, the limit equilibrium modified pseudo-dynamic method is used to analyze the stability of two-layered c-φ soil slopes in which the failure surface is assumed to be a logarithmic spiral. The zero-stress boundary condition at the ground surface under the seismic loading condition is satisfied. New formulations derived from an analytical method are proposed for the predicting the seismic response in two-layered soil. A detailed parametric study was performed in which various parameters (seismic accelerations, damping, cohesion, and angle of internal friction) were varied. The results of the present method were compared with those in the available literature. The present analytical analysis was also verified against the finite element analysis results.     

LD27-2油田稠油油藏蒸汽吞吐中后期注采参数优化研究

蒸汽吞吐是稠油油藏开发的最有效措施之一，但是对于海上油田的特殊条件，在进行蒸汽吞吐3~4轮后，即意味着进入蒸汽吞吐中后期。此时，如何调整注采参数，是海上稠油油藏高效开发的关键。针对LD27-2油田稠油油藏的开发特点，在地质建模和高度历史拟合的情况下，对LD27-2油田稠油油藏开发状况进行多轮次预测；基于生产历史拟合的油藏数值模型，开展了不同蒸汽干度、注汽强度、注汽强度递增等条件下A22H井和A23H井蒸汽吞吐至开采至10年的油藏数值模拟，明确不同注采参数的影响规律，优化了LD27-2油田稠油油藏蒸汽吞吐中后期注采参数。     

大型支撑辊的堆焊修复工艺及应用

大型支撑辊重量大、辊径大、辊面长、耐磨层厚,采用传统的堆焊工艺修复Cr3~Cr5大型支撑辊难度大,母体金属与堆焊层容易在堆焊时发生相变,导致开裂。另外,传统的轧辊堆焊修复工艺不合理,修复的轧辊力学性能较差,限制了轧辊的使用寿命,大量报废的轧辊尤其是大型轧辊长期堆积在轧钢厂内,增加了生产成本,造成了极大浪费。为此,开展了大型热轧Cr3~Cr5支撑辊及大型冷轧Cr3支撑辊焊材制备、堆焊工艺及修复技术研究。技术实施表明,修复后的支撑辊使用寿命达到新轧辊的寿命,每支堆焊修复支撑辊上机使用至报废尺寸,至少可循环堆焊修复3次,使支撑辊单项辊耗成本在每个循环周期内降低40%~60%,同时解决了大型支撑辊焊接性能不稳定的难题。     

船用重油多元模型燃料的构建与验证

为了复现实际船用重油燃料燃烧特性，基于化学解构法原理，提出了重油多元模型燃料。选择了正十四烷、2,6,10-三甲基十二烷、四氢化萘和正癸基苯作为基础燃料，表征实际重油的正构烷烃、异构烷烃、环烷烃和芳烃成分。模型燃料的比例依据带权欧几里得距离算法进行最优化求解。针对发展的多元模型燃料，基于流动反应器试验平台对模型燃料的中低温氧化特性进行点对点比较，多组分模型燃料成功复现了典型反应物、中间产物和生成物浓度随温度变化的趋势。基于“解耦法”的机理简化方法，发展了重油多组分模型燃料骨架机理。该机理成功预测了重油馏分的中低温氧化特性。基于该骨架机理进行敏感性分析，得到出烷烃类自由基主导的基元反应对重油碳烟生成密切相关。此外，基于定容燃烧装置数值仿真结果，证明了重油多组分模型燃料对近发动机条件下的喷雾燃烧过程具有较高的预测能力。     

各缸废气再循环率不均匀性对柴油机排放影响的试验研究

针对一台由国五升级到国六的重型柴油机原始排放(无后处理系统)超过目标设定值的问题进行研究,提出了一种通过控制各缸废气再循环(exhaust gas recirculation,EGR)率不均匀性来降低柴油机原始排放的方法。建立了柴油机各缸EGR率不均匀性的排放测试试验台架和测试方法,通过分析排放万有特性曲线图确定所研究的进气总管EGR率和柴油机运行工况点,用CO2法在稳态工况下测量各缸EGR率,分析各缸EGR率不均匀对排放性能的影响,确定了达到企业原始排放目标设定值的各缸EGR率不均匀性范围,实现了通过控制各缸EGR率不均匀性来降低柴油机原始排放及降低满足国六排放法规后处理系统匹配难度和成本的目的。     

考虑高山影响的UHVDC单极大地运行感应电势分析

特高压直流输电系统单极—大地回路运行时,会使附近交流电网遭受直流偏磁危害,地表电位的准确求解是预防和治理直流偏磁危害的重要环节。针对高山对感应电势的影响,首先建立了考虑高山影响的复合土壤结构模型,并运用镜像法与行波法推导出感应电势的计算公式,分析了大地参数对感应电势分布的影响,发现高山的存在抬高了高山与直流接地极之间的感应电势,增大了高山两侧的感应电势差。进而以±800kV天中特高压直流输电工程为例,在Matlab中搭建模型计算哈密地区交流电网中直流电流分布情况。结果表明,各变电站接地极的直流电流仿真值与实测值相符。