深海超高压环境模拟容器裂纹评定

深海超高压环境模拟容器用于模拟水下压力环境,其容器壁上承受反复载荷,容易产生疲劳裂纹.疲劳裂纹扩展是影响其断裂的主要因素.本文旨在分析半椭圆裂纹在老化的深海超高压环境模拟容器中的扩展行为,评估容器的安全性,因此对材料20MnMoNb钢的裂纹扩展特性进行了试验研究,首先考虑三角形和梯形加载情况,通过比较两组实验结果,考察了其材料对保载时间的敏感性.采用基于统一的裂纹扩展率模型的三维有限元方法进行了疲劳裂纹扩展计算,并通过CT试样的一组数值和实验结果进行了验证,最后建立了不同初始尺寸、展弦比和倾角的裂纹有限元模型,并根据裂纹在容器内壁的容许深度准则,计算了容器的剩余寿命.其分析结果可为深海超高压环境模拟容器可靠性评估提供参考.     

城市道路沥青路面补强设计方案浅析

抚顺市城市道路建设近年来有了很大发展,但城市道路使用到一定年限后,如果使用性能降低,就要及时进行补强。以抚顺市城市道路沥青路面补强设计的现状为基础,探讨了合理的沥青路面补强设计方案。     

A new method for absolute datum transfer in seafloor control network measurement

To decrease the time consumption and the labor intensity in the absolute datum transfer of traditional seafloor control network measurement, a new method, namely sailing-circle positioning method, is put forward in this paper. First, the traditional intersection positioning model is improved by considering the equivalent sound velocity profile error as an unknown parameter in the adjustment model. Second, the effect of geometric dilution of precision (GDOP) on positioning accuracy is analyzed. By seeking for the minimum of GDOP, it is concluded that the absolute datum transfer can achieve the highest accuracy in the condition of sailing along a circle relative to other sailing paths. Moreover, the optimal radius of the circle for the accurate datum transfer is also given out. Besides, the correlation between the accuracy of datum transfer and the sound velocity error in this method is analyzed. Finally, the new method was tested and verified by the experiments in Songhua lake with the water depth of 60 m and in South China sea with the water depth of 2000 m, respectively. These experiment results show that the new method can improve the accuracy and efficiency of traditional datum transfer method significantly.     

对地铁运营物资高效管理的探讨

随着城市轨道交通的快速发展,轨道交通网络加剧成型,物资供应和保障面临巨大挑战,探讨新的物资管理模式势在必行。本文着重围绕供应链中的各个实施要点阐述,从价格比对体系、采购计划、供应商、库存管理和物资配送等方面进行了论述,对于从事轨道交通物资管理的相关人员有一定的参考和借鉴意义。     

大倾角中厚煤层软弱顶底板柔性护巷技术

在大倾角中厚煤层沿空留巷中,以往的支护方式难以满足大倾角中厚煤层巷道特殊的围岩结构稳定的需要,同时无法适应工作面内矸石垮落造成留巷困难。文章针对这一难题,首次提出并采用了"柔性护巷"技术,通过利用巷道上帮形成的由垮落矸石堆积在特制钢筋网上的"包护带",允许巷道顶板有一定的下沉量,从而使矸石充分为巷道顶板组合岩梁结构提供支撑力。在总结其施工工艺的基础上,通过现场试验,研究了巷道矿压显现规律、顶板移动规律、矸石垮落堆积规律和钢筋网变形规律;实验结果表明,在利用锚、网、索、支柱联合支护的基础上,应用"柔性护巷"技术能有效地解决大倾角中厚煤层沿空留巷技术难题。     

铁路预应力路堤加固技术数值研究

研究目的:铁路预应力路堤在国内外尚属一种新型路基加固法,其受力变形特性暂未得到系统化研究,相关加固设计理论仍处于探索性阶段。因此,有必要通过数值手段了解预应力路堤的工作状态,以掌握其加固性能。鉴于此,借助ABAQUS软件平台构建预应力路堤仿真系统,分析差异化预应力加固参数对路堤变形和承载能力的影响以及预应力加固构件的受力特征。研究结论:(1)路堤本体段坡面较优加固位置为距本体顶面以下0.3倍本体高度处;(2)坡率1∶1的预应力路堤在第1、2排侧压板分别施加50 k Pa、100 k Pa预压荷载时,其变形与承载力均可达传统路堤(坡率1∶1.5)水平,并可通过提升加固标准进一步强化路堤承载性能;(3)当对第1、2、3排侧压板分别施加50 k Pa、100 k Pa、100 k Pa预压荷载时,路堤内部附加围压S11>13.5 k Pa区域大致呈"x"形分布并形成横贯路堤的"预压加固区";(4)侧压板锚固区受力集中且复杂,应注意保障锚固区板体强度;(5)力筋在路堤加载前后的应力变化量与坡面侧向变形特征相关;(6)本研究成果可为铁路预应力路堤的加固设计提供技术指导。     

基顶支撑不均匀度对道面板厚度影响分析

为研究土基基顶反应模量不均匀性对机场跑道结构力学性能的影响规律,针对基顶反应模量分布不均匀度及交通荷载耦合作用对混凝土道面板的受力进行有限元分析,分析相同轮载下为保证刚性道面板受力安全时基顶支撑不均匀度对混凝土道面板厚度的影响,探讨不同机型轮载对应不同道面板厚度情况下的基顶支撑不均匀度控制的临界参数。分析结果表明:混凝土板弯拉应力随着基顶支撑不均匀度的增加而增大,其影响随飞机轮载不同而存在差异,为避免道面产生严重损伤,需要增大道面板厚度。对于需要运行A320飞机的跑道,当道面铺设厚度为0.36、0.38和0.40 m时,基顶支撑不均匀度最大值分别不宜超过38%、57.5%和70%。对于拟运行B737-800飞机的跑道,当板厚为0.36 m时板的弯拉应力超过限值而发生弯拉破坏;道面铺设厚度分别为0.38、0.40 m时,为保证道面板受力安全的基顶支撑不均匀度最大值分别不宜超过33%和62%。     

CT reconstruction with priori MRI images through multi-group datasets expansion

Computed tomography (CT) reconstruction with a well-registered priori magnetic resonance imaging (MRI) image can improve reconstruction results with low-dose CT, because well-registered CT and MRI images have similar structures. However, in clinical settings, the CT image of patients does not always match the priori MRI image because of breathing and movement of patients during CT scanning. To improve the image quality in this case, multi-group datasets expansion is proposed in this paper. In our method, multi-group CT-MRI datasets are formed by expanding CT-MRI datasets. These expanded datasets can also be used by most existing CT-MRI algorithms and improve the reconstructed image quality when the CT image of a patient is not registered with the priori MRI image. In the experiments, we evaluate the performance of the algorithm by using multi-group CT-MRI datasets in several unregistered situations. Experiments show that when the CT and priori MRI images are not registered, the reconstruction results of using multi-group dataset expansion are better than those obtained without using the expansion.     

全自动化码头发展视域下的集装箱可视化智能理货系统研究

当今,在信息化程度非常高的自动化、无人化集装箱码头理货,常规人盯岸桥的方式已经落伍,我国理货行业如何突破传统理货技术瓶颈,打造适应成本最低、效率最高的整合后物流链的生产工艺已成为行业发展的关键课题。通过现场安装摄像头,采用OCR、RFID、PLC、激光、红外线等进行智能识别箱号、拖车号、拍照验残、全程监控,经过理货业务智能处理系统的处理等,最终实现了通过室内监控即可进行集装箱理货信息的实时传输与共享,体现人性化操作的同时实现了理货的智能化。这一理货工艺的革新加快推动了理货行业的转型升级,并能取得良好的经济效益和社会效益。     

Robust control for four-wheel-independent-steering electric vehicle with steer-by-wire system

A four-wheel-independent-steering (4WIS) electric vehicle (EV) with steer-by-wire (SBW) system is proposed in this paper. The fast terminal sliding mode controller (FTSMC) is designed for the SBW system to suppress external disturbances. Taking unstructured and structured uncertainties into consideration, a robust controller is designed for the 4WIS EV utilizing μ synthesis approach and the controller order reduction is implemented based on Hankel-Norm approximation. Since sideslip angle is the feedback signal of robust controller and it is hard to measure, the extended Kalman filter (EKF) is employed to estimate sideslip angle. To evaluate the vehicle performance with the designed control system, step and sinusoidal steering maneuvers are simulated and analyzed. Simulation results show that the designed control system have good tracking ability, strong robust stability and good robust performance to improve vehicle stability and handing performance.