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581.
谷维忠 《大连铁道学院学报》1989,(4)
本文论述了耐候钢耐腐蚀及高强度的特点,给出了其经试验得到的有关冲压性能和冲压工艺参数,为拟定工艺和设计模具提供了依据. 相似文献
582.
583.
桩承式水平加筋复合地基是"水平向增强体+竖直向增强体"的联合复合地基.计算路堤下复合地基桩土应力比的方法与刚性基础下的复合地基不同.路提由填土等散体材料组成,路堤下复合地基桩与桩间土之间的沉陷不一致,导致填土内部出现相对垂直位移,应力状态发生变化.由于复合地基桩土应力比发生变化及水平向增强体的提拉作用,可将大部分路堤荷载转移到桩体上,从而减小桩间土上部的压力,并使得路堤顶面的差异沉降减小.通过分析桩承式水平加筋复合地基及其上部填土的变形特点,推导出求解加筋垫层上、下方桩顶土压力、桩问土压力及桩土应力比的计算公式并分析了不同参数对桩土应力比的影响. 相似文献
584.
结合某轻型卡车车架的开发工作,对车架进行有限元分析。首先应用HyperWorks软件,选择合理的单元类型进行车架网格划分、螺栓连接和焊接结构的模拟,建立带有驾驶室、车厢、各支架以及前后钢板弹簧悬架的较为完整的整车有限元模型,研究不同工况下的约束和载荷添加方式,并使用NX.Nastran求解出车架在不同工况下的应力分布。然后根据计算结果,对车架进行改进设计和轻量化设计,优化设计的车架比原设计重量减少了4.93%,且解决了强度不足的问题。最后,对车架样件进行弯曲工况下的应力试验,试验数据和有限元计算结果有较好的一致性。 相似文献
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南水北调东线工程正式运行后,盐邵船闸上游长期处于高水位,闸室系船设施不能满足大型船舶高水位系缆要求。文中分析了过闸大型船舶的尺度、系缆特点,对船闸闸室结构安全进行验算,研究优化闸室高水位系船设施应急改造方案,取得了良好的使用效果。 相似文献
587.
Data mining using regularized adaptive B‐splines regression with penalization for multi‐regime traffic stream models
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This paper presents a new data mining method that integrates adaptive B‐spline regression and traffic flow theory to develop multi‐regime traffic stream models (TSMs). Parameter estimation is implemented adaptively and optimally through a constrained bi‐level programming method. The slave programming determines positions of knots and coefficients of the B‐spline by minimizing the error of B‐spline regression. The master programming model determines the number of knots through a regularized function, which balances model accuracy and model complexity. This bi‐level programming method produces the best fitting to speed–density observations under specific order of splines and possesses great flexibility to accommodate the exhibited nonlinearity in speed–density relationships. Jam density can be estimated naturally using spline TSM, which is sometimes hardly obtainable in many other TSM. Derivative continuity up to one order lower than the highest spline degree can be preserved, a desirable property in some application. A five‐regime B‐spline model is found to exist for generalized speed–density relationships to accommodate five traffic operating conditions: free flow, transition, synchronized flow, stop and go traffic, and jam condition. A typical two‐regime B‐spline form is also explicitly given, depending only on free‐flow speed, optimal speed, optimal density, and jam density. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
588.
随着区域一体化推进,天津港已日益成为一个区域性的重要空间节点。结合天津港所处内外部环境变化及其自身发展的新动向,对当前天津港规划建设所面临的新特点进行阐述。在此基础上,提出今后天津港规划适应性的策略建议。 相似文献
589.
As image-guided navigation plays an important the pre-operative images with the intra-operative patient role in neurosurgery, the spatial registration mapping position becomes crucial for a high accurate surgi- cal output. Conventional landmark-based registration requires expensive and time-consuming logistic support. Surface-based registration is a plausible alternative due to its simplicity and efficacy. In this paper, we propose a comprehensive framework for surface-based registration in neurosurgical navigation, where Kinect is used to auto- matically acquire patient's facial surface in a real time manner. Coherent point drift (CPD) algorithm is employed to register the facial surface with pre-operative images (e.g., computed tomography (CT) or magnetic resonance imaging (MRI)) using a coarse-to-fine scheme. The spatial registration results of 6 volunteers demonstrate that the proposed framework has potential for clinical use. 相似文献
590.
Virtual reality (VR) based vascular intervention training is a fascinating innovation, which helps trainees develop skills in safety remote from patients. The vascular intervention training involves the use of flexible tipped guidewires to advance diagnostic or therapeutic catheters into a patient's vascular anatomy. In this paper, a real-time physically-based modeling approach is proposed to simulate complicated behaviors of guidewires and catheters based on Kirchhoff elastic rod. The slender body of guidewire and catheter is simulated using more efficient special case of naturally straight, isotropic Kirchhoff rods, and the short flexible tip composed of straight or angled design is modeled using more complex generalized Kirchhoff rods. We derive the equations of motion for guidewire and catheter with continuous elastic energy~ and then they were discretized using a linear implicit scheme that guarantees stability and robustness. In addition, we apply a fast-projection method to enforce the inextensibility of guidewire and catheter, while an adaptive sampling algorithm is implemented to improve the simulation efficiency without reducing accuracy. Experimental results reveal that our guidewire simulation method is both robust and efficient in a real-time performance. 相似文献