基于BIM模拟128 m铁路钢桁梁原位拼装技术研究

以蒙华铁路湖南段京广铁路特大桥跨通海路128 m简支钢桁梁拼装为研究对象,阐述利用BIM技术模拟钢桁梁支架原位拼装施工方法。建立钢桁梁桥整体BIM模型,进行各部件间碰撞检查,提高加工制作效率,降低返工风险;建立钢桁梁桥原位拼装支架体系和起重龙门吊BIM模型,利用BIM技术进行场地优化布置,并对施工方案进行优化,确保施工安全;模拟钢桁梁拼装BIM技术的应用,实现了钢桁梁杆件精确加工和精准安装目标,保证了拼装质量和工期、提升了企业核心竞争力、取得了良好的经济和社会效益。     

压载水UV处理装置优化设计及实验研究

IMO制定的压载水处理D2标准已对颗粒物和细菌及微生物的数量等做了明确的规定,利用紫外线杀菌具有高效、洁净、方便的特点。提出了对原有的UV处理装置内增加了进出口导流板和筒体内平面导流板,它改善了UV处理装置内的流场分布和辐照剂量的均匀性。模拟结果显示,优化后的装置它的平均流速为1.18m/s,低于原先的2.43m/s平均流速,使辐照时间增加了1.030s,辐照剂量呈正态分布。通过生物实验测试,验证了优化后的装置能将10~50μm生物数量控制为平均0.02cfu/ml,50μm以上生物数量控制为2.33cfu/m3。在紫外灯管数量及功率未增加情况下,它节约了处理时的能耗,达到了理想的杀菌效果。     

锚下有效预应力安全性富余度研究

通过有限元分析预制T梁在不同欠张拉状态下的受力性能,确定预应力结构处于安全状态时临界值;通过足尺寸（25 m）T梁试验,分析其在荷载作用下的应变和挠度,通过实测值与理论值的比较,表明结构处于安全状态时临界值的可靠性;比较临界值与锚下有效预应力取值合理范围,得出锚下有效预应力安全性富余度。     

汽车用Fe-Mn-C系TWIP钢的性能研究

从两个方面研究了汽车用Fe-Mn-C系TWIP钢,一方面从生产工艺上,研究了退火热处理工艺对力学性能的影响,探讨了其工业生产的可行性;另一方面通过原位拉伸试验观察其变形过程中微观组织的变化,探讨了其高强度高塑性的微观机理.研究表明TWIP钢在拉伸变形过程中出现了多种变形机理的相互协调,即滑移带变形、孪生变形和切变带变形在不同的变形阶段起主导作用,因而使TWIP钢兼备高强度和高塑性.     

大跨度连拱隧道支护体系的现场监测及数值模拟

文章对某大跨度连拱隧道施工全过程进行现场监测,在监测结果的基础上,结合数值模拟进行分析与研究,得出大跨度连拱隧道在开挖过程中的力学特征.结果表明：（1）上台阶开挖对钢支撑受力的空间效应明显,是隧道支护监测的控制点;（2）钢支撑和二衬前期内力增加较快,随后逐渐趋于稳定,二衬内力大约1年内趋于稳定;（3）中墙侧衬砌最易受到临洞施工影响,衬砌受力也最复杂;（4）对大跨度连拱隧道进行数值模拟一定程度上能得到开挖过程中的力学特征,但是由于隧道跨度大,地质条件复杂,开挖步骤多,数值模拟结果与实际有较多不同.     

基于实测沉降的固结度分析法

通过对某机场扩建项目填海及软基处理工程的原位监测情况,利用双曲线法、指数三点法和Asaoka法3种不同方法预测地基最终沉降,并计算平均固结度,分析软基处理效果.同时,基于实测沉降和曾国熙分级加荷法建立简化计算模型,计算地基固结度,并将该固结度计算值与地基平均固结度进行比较,结果表明该方法是合理可行的.     

黄土高填方路堤沉降影响因素及控制技术研究

与一般路基相比,高填方路基具有填方高度大、较高耐久性和稳定性等特点,具有施工成本低、使用寿命长等优点。为保证道路的稳定和可持续发展,在我国山区公路经过地势低洼地区路段时,往往采用高填方路堤形式。然而,高填方路堤会出现严重的沉降,从而导致路基不稳定,特别是在黄土地区。通过具体工程实例,对黄土地区高填方路堤沉降进行现场监测,对其沉降影响因素及控制技术进行总结分析,为黄土地区高填方路堤建设提供更好的指导。     

Pedestrian detection for traffic safety based on Accumulate Binary Haar features and improved deep belief network algorithm

ABSTRACT

In order to improve traffic safety and protect pedestrians, an improved and efficient pedestrian detection method for auto driver assistance systems is proposed. Firstly, an improved Accumulate Binary Haar (ABH) feature extraction algorithm is proposed. In this novel feature, Haar features keep only the ordinal relationship named by binary Haar features. Then, the feature brings in the idea of a Local Binary Pattern (LBP), assembling several neighboring binary Haar features to improve discriminating power and reduce the effect of illumination. Next, a pedestrian classification method based on an improved deep belief network (DBN) classification algorithm is proposed. An improved method of input is constructed using a Restricted Bolzmann Machine (RBM) with T distribution function visible layer nodes, which can convert information on pedestrian features to a Bernoulli distribution, and the Bernoulli distribution can then be used for recognition. In addition, a middle layer of the RBM structure is created, which achieves data transfer between the hidden layer structure and keeps the key information. Finally, the cost-sensitive Support Vector Machine (SVM) classifier is used for the output of the classifier, which could address the class-imbalance problem. Extensive experiments show that the improved DBN pedestrian detection method is better than other shallow classic algorithms, and the proposed method is effective and sufficiently feasible for pedestrian detection in complex urban environments.     

Modelling mode choice for freight transport using advanced choice experiments

In this paper we use advanced choice modelling techniques to analyse demand for freight transport in a context of modal choice. To this end, a stated preference (SP) survey was conducted in order to estimate freight shipper preferences for the main attributes that define the service offered by the different transport modes. From a methodological point of view, we focus on two critical issues in the construction of efficient choice experiments. Firstly, in obtaining good quality prior information about the parameters; and secondly, in the improved quality of the experimental data by tailoring a specific efficient design for every respondent in the sample.With these data, different mixed logit models incorporating panel correlation effects and accounting for systematic and random taste heterogeneity are estimated. For the best model specification we obtain the willingness to pay for improving the level of service and the elasticity of the choice probabilities for the different attributes. Our model provide interesting results that can be used to analyse the potential diversion of traffic from road (the current option) to alternative modes, rail or maritime, as well as to help in the obtaining of the modal distribution of commercial traffic between Spain and the European Union, currently passing through the Pyrenees.     

聚苯胺／CuFeS2纳米复合材料的制备与表征

聚苯胺/CuFeS2（PANI/CuFeS2）纳米复合材料不仅具有导电高聚物和氧化物半导体的优良光电特性,还具有纳米材料特有的功能性,在传感、催化、吸波和能源材料等领域有着广阔的应用前景。文中采用原位聚合法制备了PANI/CuFeS2纳米复合材料,分别采用傅立叶红外光谱（FT-IR）、X-射线衍射（XRD）、扫描电镜（SEM）、UV-Vis 漫反射吸收光谱和电导率测量等对所得复合微粒进行表征。结果表明：CuFeS2纳米颗粒均匀的分散在聚苯胺（ PANI）基体内,PANI/CuFeS2复合材料中未存在键合作用,而只是简单的物理包覆,所以对各自的性能均未造成影响。与聚苯胺相比,PANI/CuFeS2复合材料光电性能得到有效提高,且CuFeS 2添加量为30％时其性能最佳。