Analytical framework for ex-post evaluation of transport projects: Lessons learnt on retrospective CBA

This study deals with the ex-post evaluation of ten major transport projects which were co-financed by the European Regional Development Fund and the Cohesion Fund in the period 2000–2013 and located across nine EU Member States. The original contribution of this study is represented by the combination of the traditional ex-post Cost–Benefit approach with a qualitative analysis. Specifically, a retrospective Cost–Benefit analysis is used to quantify the benefits and costs of the projects, then interviews to relevant stakeholders were carried out. Ex-post CBA, when appropriately implemented and integrated with qualitative evidence, represents a powerful tool for supporting decision-making processes and for policy lessons.     

基于双谱特征的行星齿轮箱故障诊断方法

为了研究行星齿轮箱齿面磨损全生命周期实验的退化过程,使用了可以抑制高斯噪声和对信号中产生的频率耦合进行解耦的双谱方法去进行故障特征提取,提出了两个基于双谱的特征指标,双谱熵以及非高斯强度,并通过特征指标评价方法去检验其指标性能。结果表明基于双谱熵具有良好的指标性能,而且对于行星齿轮箱齿面磨损的早期微弱故障十分敏感,适用于行星齿轮箱齿面磨损的故障诊断。     

Multi-stage intelligent operation optimization for a hydrocracking fractionation system with a multi-fractionator series-parallel structure

A fractionation system is an essential unit in the hydrocracking process. Its optimal operation is challenging because of the complexity in the structure of the distillation tower and composition of the stream. In addition, the series-parallel structure between the distillation towers of different techniques aggravates the coupling and complexity of the hydrocracking fractionation system (HFS). This, in turn, increases the time complexity of the optimization problem. In this paper, a rigorous mechanism model of an actual HFS is first applied to describe the operating conditions of the HFS. Then, an improved state transition algorithm (STA) with a staged evaluation strategy is proposed to solve the above problem. To overcome problems caused by the series-parallel structure of HFS, the model is divided into multiple stages for evaluation by mechanism analysis. Furthermore, several typical convergence estimation criteria are introduced to reduce unnecessary model calculations. To solve time-consuming problems associated with HFS optimization, the adaptive change operator is used to improve the search function of the original algorithm and two performance criteria are presented to reduce the optimization time. The proposed algorithm is successfully applied to the operational parameter optimization problem of HFS with a multi-fractionator series-parallel structure. The experimental results indicated that the staged evaluation strategy improved the fast convergence probability of the HFS mechanism model and reduced unnecessary calculations, whereas the improved algorithm increased accuracy and significantly decreased optimization time.     

基于RBF神经网络的露天矿爆破效果预测研究

露天矿爆破是一个受诸多因素共同影响的系统工程,是露天开采的重要环节之一,其爆破效果的优劣直接影响后续工序的完成。提高爆破技术水平和爆破质量,对矿山安全和生产具有重要的意义。本文通过随机森林选择影响爆破效果的主要参数,结合模糊评价确定爆破综合效果,建立了RBF神经网络爆破效果预测模型。将该模型应用于矿山爆破效果预测中,并将爆破现场实测的11组数据作为模型训练样本,另外5组现场数据作为预测样本进行测试,通过与BP神经网络比较,发现RBF神经网络的预测性能更为优越,可广泛应用于现场实践中。     

基于K-均值聚类与贝叶斯判别的我国煤矿顶板灾害事故安全评价

顶板事故是我国煤矿安全生产中的重大隐患,开展顶板灾害事故安全评价,识别顶板灾害危险性是煤矿安全生产亟待解决的问题。本文在文献调研的基础上,对影响顶板灾害的影响因素进行分析,从自然因素、技术因素和管理因素三个方面构建了顶板灾害安全评价指标体系,结合专家意见对各评价指标进行量化,采用K-均值聚类与贝叶斯判别的方法对我国顶板灾害安全水平进行评价,以我国煤矿实际样本数据为研究对象开展实证分析。研究结果表明:基于K-均值聚类与贝叶斯判别的煤矿顶板安全评价方法具有较高的准确度,能够用于定量化描述煤矿顶板灾害危险,具有一定的应用前景。     

某大理岩矿山采空区稳定性评价与综合治理对策研究

某大理岩矿山采用房柱法进行开采,遗留了大量尚未充填的采空区,成为矿区及周边地区重大的安全隐患。基于采场的三维模型,选取代表性区域建立数值计算模型,利用FLAC_^3D软件进行稳定性分析。模拟结果表明,塑性区破坏以剪切破坏为主,仅存在于?90 m水平采空区拐角处,未贯通且分布范围有限,其影响深度约向围岩内部深入0.4～1.0 m,说明岩体的破坏发生在浅层,采空区不会发生大规模失稳,整体稳定性良好；结合模糊综合评判,将采空区按照稳定性划分为稳定性良好、较稳定和较不稳定三类区域。在此基础上,提出了四种采空区综合治理方案,并从方案的技术可行性、经济性和治理效果进行分析对比,确定方案一为首选方案。从而为采空区治理和综合利用、城市发展规划提供依据。     

Proposed light sources for illuminating in Xuan paper and silk artwork with organic and inorganic pigments by evaluating color shifts in museum

Artworks based on Xuan paper or silk and painted by organic or inorganic pigments are highly responsive to light due to their materials and manufacturing technologies. They belong to the highest level of light responsive exhibits stipulated by International Commission on Illumination (CIE) and are vulnerable to fading and discoloration caused by radiation from light sources. The choice of light sources is the key of protection for artworks. It is indispensible and urgent to choose the lowest damage light sources according to the material characteristics of artworks. In this article, long-term irradiation of typical light sources on various substrates and pigments was used as experimental method, and CIE DE2000 color difference formula was used as the evaluation index. The laws of the influence of different light sources on the color change of various materials were obtained, and the relative damage coefficients of light sources were calculated. Finally, eight kinds of light sources suitable for illuminating responsive artworks with typical material combinations were proposed. However, there are some limitations in the study, because the ancient Chinese Xuan paper and silk used as experimental objects in the experiment are yellowish. Thus, the models derived in this article are not suitable for choosing reasonable display light sources for other works of art. However, suitable light sources for different materials could be obtained by the calculation method used in this article.     

Development and techno-economic analyses of a novel hydrogen production process via chemical looping

In this work, a novel hydrogen production process (Integrated Chemical Looping Water Splitting “ICLWS”) has been developed. The modelled process has been optimised via heat integration between the main process units. The effects of the key process variables (i.e. the oxygen carrier-to-fuel ratio, steam flow rate and discharged gas temperature) on the behaviour of the reducer and oxidiser reactors were investigated. The thermal and exergy efficiencies of the process were studied and compared against a conventional steam-methane reforming (SMR) process. Finally, the economic feasibility of the process was evaluated based on the corresponding CAPEX, OPEX and first-year plant cost per kg of the hydrogen produced. The thermal efficiency of the ICLWS process was improved by 31.1% compared to the baseline (Chemical Looping Water Splitting without heat integration) process. The hydrogen efficiency and the effective efficiencies were also higher by 11.7% and 11.9%, respectively compared to the SMR process. The sensitivity analysis showed that the oxygen carrier–to-methane and -steam ratios enhanced the discharged gas and solid conversions from both the reducer and oxidiser. Unlike for the oxidiser, the temperature of the discharged gas and solids from the reducer had an impact on the gas and solid conversion. The economic evaluation of the process indicated hydrogen production costs of $1.41 and $1.62 per kilogram of hydrogen produced for Fe-based oxygen carriers supported by ZrO₂ and MgAl₂O₄, respectively - 14% and 1.2% lower for the SMR process H₂ production costs respectively.     

基于模糊多元联系度模型的尾矿库综合安全评价

为准确评价尾矿库的安全等级，以黄金洞尾矿库为例，分析影响尾矿库安全的各因素之间的关系，综合运用模糊多元联系度理论与层次分析法（AHP），建立了包含5个影响因素和26个影响因子的尾矿库综合安全评价模型。由AHP得出各项主、客观指标的权重系数，引入模糊多元联系度理论，综合考虑确定性与不确定性因素，处理综合集成问题，构造隶属函数量化指标的实测值。结果表明：黄金洞尾矿库安全等级为Ⅱ级，尾矿库处于较稳定状态。经比较不确定性因素大小，得出尾矿排放（B₃）>尾矿坝（B₂）>安全管理（B₁）>尾矿输送与回水（B₅）>排洪系统（B₄），说明尾矿排放指标的不确定性因素最大，需对尾矿排放加强管理。该模型得到的评价结果与实际结果相吻合，为尾矿库安全性评价提供了一种可行的方法。