天津南港航道工程疏浚施工备淤深度研究

以天津南港大航道项目为依托,通过研究航道施工期间的回淤规律,计算并推荐在施工中应预留出的备淤深度,从而达到既能满足航道设计要求、又以最优的超挖量实现施工经济性的目的,从实际施工效果来看具有良好的指导意义,为今后类似工程积累了宝贵经验。 关键词：航道疏浚;回淤;数学模型;泥沙扩散     

中空纤维膜接触器吸收低浓度CO2气体研究

采用疏水性中空纤维膜接触器为吸收装置,以一乙醇胺(MEA)为吸收液,对低浓度CO2(≤0.5%)进行吸收,考察吸收液浓度、吸收液流量、气体流量和进气CO2浓度对CO2吸收效率η和总体积传质系数KGa的影响规律.结果表明,膜吸收法可以处理浓度为0.1%～0.5%的CO2,且保持较高的吸收效率;吸收过程受气相阻力控制,液相阻力对CO2的传质性能影响不大.根据传质理论,建立传质数学模型,模型结果与试验结果基本一致.     

The Singularly Perturbed Problem for Nonlinear Nonlocal Reaction Diffusion Systems

IntroductionRecently the nonlinear singularly perturbedproblem has been investigated in the internationalacademic circles[1] .Approximation methods havebeen developed and refined,including the methodof averaging,boudary layer method,matchedasymptotic expa…     

指纹图像预处理方法的研究与比较

指纹图像预处理需针对不同的噪声产生原因而采用不同的方法,先对采集到的退化图像进行Wiener滤波。然后对复原后的图像进行增强预处理．着重对主要预处理方法Gabor方法和各向异性扩散技术进行了分析对比,并就这些方法中的参数选择进行了对比研究．     

AIG based nonlinear anisotropic smoothing strategy for vector-valued images

The effects of the Rician noise on the calculated tensors are analyzed and an affine invariant gradient (AIG) based nonlinear anisotropic smoothing strategy is presented. The AIG based smoothing strategy is a development of the affine invariant nonlinear anisotropic diffusion (AINAD) restoration model, introduced by Guillermo Sapiro, and adopted to restore vector-valued data. To evaluate the efficiency of the presented AINAD model in accounting for the Rician noise introduced into the vector-valued data, the peak-to-peak signal-to-noise ratio (PSNR), signal-to-mean squared error ratio (SMSE) and Beta(parameter that stands for edge preservation) metrics are used. The experiment results acquired from the synthetic and real data prove the good performance of the presented filter.     

生物岛-大学城沉管隧道灌砂试验及结果分析

 基础灌砂是沉管隧道施工中的重要环节,通过试验模拟灌砂过程,寻找各参数之间的相互关系,对原设计灌砂配合比进行验证分析。单孔灌砂时,除4个角外,管节模型底部砂盘溢出,砂盘表面平坦密实;双孔灌砂时,先灌砂孔部位发展相对较好,砂盘扩展充分。不同配合比砂盘的发展有所不同,同等灌砂压力下含砂量越高,扩散半径越小。砂基础承载力和密实度完全满足设计要求,但砂盘密实度由于不同的配合比有所差别,砂盘边缘处与冲击坑边缘处密实度相对较低。     

高速公路收费站区空气污染特征分析与数值模拟

根据高速公路收费站区实际环境,考察来流风向与风速、车流量、建筑物等因素时机动车排放污染物扩散的影响,建立高速公路收费站区污染物扩散的CFD仿真模型,进行三维流场的数值模拟,运用风向频率加权模型,比较模拟结果与实地采样分析数据,预测探讨高速公路收费站区空气流场和污染物迁移扩散特征.结果表明,数值模拟结果和实测数据符合较好,显示两者具有良好相关性;受收费站布局和大气边界层的影响,在建筑物背风面形成气流漩涡,污染物难以扩散形成局部高浓度污染,在环境温度25℃,风速1.9 m·s-1,小时车流量为465 veh.h-1,NOx的浓度达到0.232 mg·m-3;污染物扩散特征主要受环境建筑、气象条件及车流量的影响,在1.5～2 m高度范围污染物呈现较高的浓度.     

Methods for forecasting the market penetration of electric drivetrains in the passenger car market

Current car technologies will not solve upcoming challenges of mitigating greenhouse gas emissions in road transport. Projections of the market penetration by alternative drive train technologies are controversial regarding both forecast market shares and applied scientific methods. Accepting this latter challenge, we provide a (so far missing) overview of methods applied in this field and give some recommendations for further work. Our focus is to classify the applied methods into a convenient pattern and to analyse models from the recent scientific literature which consider the electrification of light-duty vehicles. We differentiate the following bottom-up approaches: Econometric models with disaggregated data (such as discrete choice), and agent-based simulation models. The group of top-down models are subdivided into econometric models with aggregated data (e.g. vehicle stock data), system dynamics, as well as integrated assessment models with general equilibrium models. It becomes obvious that some methods have a stronger methodological background whereas others require comprehensive data sets or can be combined more flexibly with other methods. Even though there is no dominant method, we can identify a trend in the literature towards data-driven hybrid approaches, which considers micro and macro aspects influencing the market penetration of electric vehicles.     

日照港吹填施工中污染物扩散数值分析

在海州湾日照港北区港口岸线退岸还海修复整治工程中,拟采用疏浚工程船舶在近海岸进行吹填施工形成黄金海岸,沙滩面积44.97万m2。针对吹填施工中海沙中的污染物会在海水中扩散而污染海洋环境的问题,对吹填过程中污染物的扩散进行预测。采用计算流体动力学（CFD）方法,就近海岸吹填施工中污染物扩散趋势进行数值模拟,分析污染物扩散情况,评价施工方案对海洋环境污染的风险。根据污染物扩散趋势及分析结果,提出防污屏布置方案。实践证明,在吹填工程中应用防污屏能够防止污染物扩散。     

中间夹层与碳钢和不锈钢复合板的制备工艺与性能研究

以Mg-Cu-Al合金作为中间夹层材料,研究了热轧法制备不锈钢/碳钢复合板的工艺,探讨了不同的实验轧制温度、轧制速度、中间夹层厚度、变形量以及二次轧制参数对其显微组织的影响,并对铝合金中间夹层两侧的扩散层的厚度、显微硬度及组织进行了测定,对复合板的拉伸及剪切性能进行了测试.实验结果表明,在首次轧制温度600℃～635 ℃,轧制速度8～24 mm/min,中间夹层厚度0.6～0.9 mm,变形量14%～28 %,二次轧制温度660℃～680 ℃,轧制速度16～24 mm/min,变形量21%～35 %工艺条件下,复合板碳钢侧扩散层厚度可达61 μm,不锈钢侧扩散层厚度可达50 μm,显微硬度达到HV0.025 1 000;扩散层主要由Fe2Al5相组成;复合板的抗拉强度达到526 MPa,剪切强度达到85 MPa.