我国隧道及地下工程发展现状和前景展望

就我国隧道及地下工程发展现状和前景展望为题展开了研究,开始我们介绍了隧道及地下工程的发展现状,然后我们介绍了隧道及地下工程在施工中用到的方法和技术,最后我们对隧道及地下工程的未来做了展望并提出了施工中要注意的地方。     

高等级公路煤系地层高边坡防护的设计及施工

通过广清高速公路高边坡的设计及施工实践,分析了煤系地层的地层岩性特点和高边坡破坏机理及模式,提出了相应的处治措施,介绍了关键工序的施工工艺及注意事项,取得了较好的处治效果。     

路线经过滑坡地段的防治方案及施工要点

滑坡的成因及形式多种多样,预防及治理方案也不尽相同。较为全面地阐述了滑坡防治的诸多方案及适用条件,指出了滑坡处治施工中的注意要点。     

乳化沥青生产工艺及质量控制问题研究

简要介绍了乳化沥青的品种、适用范围及乳化机理,介绍了乳化沥青的生产流程。总结了乳化沥青的质量及储存中经常出现的问题,并进行分析,找出原因及解决对策。     

钢筋混凝土及预应力混凝土桥梁裂缝分析

介绍了钢筋混凝土及预应力混凝土桥梁裂缝种类及部分裂缝的成因及解决办法。     

浅议路桥建设项目的变更和索赔管理

基于对工程变更及索赔的概念及产生原因了解的基础上,分析了目前路桥建设项目的工程变更及索赔的概念、管理现状,提出了路桥建设项目工程变更管理及索赔的计算方法及若干技术要点、处理程序,从不同方面论述了强化路桥工程变更及索赔管理,以实现工程预期目标。     

粉煤灰对混凝土抗氯离子渗透性的影响分析

探讨了粉煤灰对混凝土抗冻融耐久性及氯离子渗透性的影响。在所得试验数据的基础上,根据粉煤灰特性及混凝土耐久性的机理分析了这些变化情况,从而初步确定出了粉煤灰对混凝土抗冻融耐久性及氯离子渗透性的影响情况。     

浅析路基冻胀与翻浆

简要分析了冻胀与翻浆的成因以及冻胀与翻浆之间的关系。结合实际谈了不同路面的不同反映及影响冻胀与翻浆的因素。对治理翻浆及冻胀提出设计要求及防治的基本途径     

浅谈超限运输对公路桥梁的破坏

分析了超限运输对各种桥梁结构及桥面系的破坏机理及病害状况,并探讨了解决对策及桥梁养护中应注意的问题。     

路面清扫车的选型及使用

本文对路面清扫车的选型及使用进行了阐述,指出了目前清扫车存在的问题,并提出了改进意见及展望。     

光纤传感器在桥梁监控中的应用分析

光纤传感器与传统的电测传感器相比具有精度高,抗干扰能力强,适用范围广等特点,能够完成桥梁结构的应变、裂缝、振动等多种物理量的测量.不但能实现结构物中点的物理量测试,而且能够进行分布式网络测量.探讨了光纤传感器的主要特性和应用特点,提出了合理选择该类传感器的注意事项.     

160Gbps光通信系统中光纤准直器的基准插入损耗与功率代价研究

在几何光学和高斯光束传输理论的基础上,运用矩阵光学原理与高斯光束耦合理论,分析了基于自聚焦透镜光纤准直器引入高速光通信系统的基本插入损耗、回波损耗等特性,并采用光纤衰减基准测试方法对理论计算进行了实验验证.在160 Gbps光通信系统中分析了该器件对系统传输性能的影响,对误码率曲线进行了测试对比,讨论了光纤准直器增大系统功率代价的原因.     

基于光纤光栅的斜拉桥索力在线监测

应用光纤传感测试技术，将光纤光栅刚性粘贴于传感头外表面上，使传感头承受拉索的索力，通过对光纤光栅波长移动量的解调，就可以测出索力的大小。并将光纤光栅和电阻应变片两种索力测量方法进行了实验对比。实验结果与理论分析证明。该测试系统具有结构简单、测量范围大、稳定性和线性度好等特点，既可用于斜拉桥施工阶段的索力测定，也可用于结构长期的安全监测。     

Dynamic wavelength and bandwidth allocation using adaptive linear prediction in WDM/TDM ethernet passive optical networks

Hybrid wavelength-division-multiplexing (WDM)/time-division-multiplexing (TDM) ethernet passive optical networks (EPONs) can achieve low per-subscriber cost and scalability to increase the number of subscribers. This paper discusses dynamic wavelength and bandwidth allocation (DWBA) algorithm in hybrid WDM/TDM EPONs. Based on the correlation structure of the variable bit rate (VBR) video traffic, we propose a quality-of-service (QoS) supported DWBA using adaptive linear traffic prediction. Wavelength and timeslot are allocated dynamically by optical line terminal (OLT) to all optical network units (ONUs) based on the bandwidth requests and the guaranteed service level agreements (SLA) of all ONUs. Mean square error of the predicted average arriv-ing rate of compound video traffic during waiting period is minimized through Wiener-Hopf equation. Simulation results show that the DWBA-adaptive-linear-prediction (DWBA-ALP) algorithm can significantly improve the QoS performances in terms of low delay and high bandwidth utilization.     

Wavelength reservation scheme with switch fabric status in distributed mesh optical networks

A new wavelength reservation scheme is proposed to mitigate the connection setup time and minimize the reconfiguration times of optical cross-connects (OXCs) for WDM optical networks in this study. In this scheme, we consider the reconfiguration information of switch fabrics in the signaling protocol, which is designated as the signaling with switch fabric status (SWFS). Distributed reservation algorithms will reserve the wavelength with minimum of reconfiguration times of OXCs along the route. Simulation results indicate that the proposed schemes with switch fabrics status have shorter setup time, lower switching ratio as well as better blocking performance than those of the traditional classic schemes. Moreover, the proposed schemes with SWFS significantly reduce the number of switch fabrics that need to be reconfigured. Foundation item: the National Natural Science Foundation of China (Nos. 60632010 and 60572029) and the National High Technology Research and Development Program (863) of China (No. 2006AA01Z251)     

A closed form solution to segment 3D motion using straight-line optical flow

A closed form solution to the problem of segmenting multiple 3D motion models was proposed from straight-line optical flow. It introduced the multibody line optical flow constraint （MLOFC）, a polynomial equation relating motion models and line parameters. The motion models can be obtained analytically as the derivative of the MLOFC at the corresponding line measurement, without knowing the motion model associated with that line. Experiments on real and synthetic sequences were also presented.     

Effect of oxygen content on structural and optical properties of single Cu2O film by reactive magnetron sputtering method

Cuprous oxide (Cu₂O) thin films have been deposited on glass substrate by reactive magnetron sputtering method using Cu target and argon oxygen gas atmosphere. Effect of oxygen flow rate on structural and optical properties of thin films has been discussed. The results of X-ray diffraction, ultraviolet-visible spectrophotometry and atomic force micrograph indicated that the condition window for single Cu₂O phase was about 3.8 to 4.4 cm³/min, and the optimum oxygen flow rate was 4.2 cm³/min. The optical band gap E _g of Cu₂O film was determined by using the data of transmittance versus wavelength, and slightly decreased from 2.46 to 2.40 eV with the increase of oxygen flow rate from 3.8 to 4.4 cm³/min. The Cu₂O film formed at the oxygen flow rate of 4.2 cm³/min had an optical band gap of 2.43 eV.     

车辆脱轨机理及预防脱轨的对策

通过现场调研,在阐述三种脱轨机理,即爬轨脱轨、滑轨脱轨和跳轨脱轨的基础上,系统总结分析了目前各种车辆脱轨的安全评判标准及有待解决的问题,进而通过对脱轨试验情况分析并提出了五种车辆脱轨的类型及其脱轨预防对策.     

低动力作用货车转向架动力性能的研究

本文探讨低动力作用货车转向架的原理及其动力性能的计算和评估方法。首先定义9项指标,作为衡量车辆对轨道动力作用的标准。然后研究这些指标的诸因素。在此基础上总结出实现低动力作用的基本途径。本文还应用这些研究成果,提出4种低动力作用货车转向架的设计方案,并通过数值计算,同国内、外主型货车转向架对比,从而论证其在我国铁路采用的可行性。     

等参单元在货车转向架强度计算中的应用

推导了八节点六面体等参单元的应变矩阵、刚度矩阵,对该单元的位移解收敛性和畸变敏感性进行了分析。针对转向架强度分析的特点,在MATLAB平台上开发了一套求解位移的有限元程序。该程序通过读取ANSYS软件输出的数据文件中的模型信息,采用八节点六面体等参单元,求出单元刚度矩阵及单元体积力矩阵,组集单元,引入位移边界条件,得到一组以节点位移为未知量的多元线性方程组,求解得到单元节点位移。最后对160 km/h货车转向架侧架的主要载荷进行了位移计算,结果与ANSYS软件计算结果基本吻合。