河北北部山区通村公路土基回弹模量对路面设计的影响研究

通过对河北北部山区通村公路进行现场试验,由回归分析得到土基回弹模量与弯沉的关系式,并根据不同土基强度与不同标准轴载对路面厚度设计的影响,对土基强度进行分级,可作为路面设计的依据。     

一种自适应正则化参数和模数的图像去卷积方法

自适应正则化方法是解决图像去卷积问题中平滑噪声和保持边缘矛盾的一种方法,传统的自适应正则化方法只考虑到图像的整体信息而忽略了图像内部不同区域的细节信息,本文提出的自适应正则化方法,利用Katsaggelos自适应正则化参数,自适应的改变正则化参数,并通过图像内部不同区域的信息自适应改变正则化模数矩阵．从而实现了平滑噪声和保持边缘的平衡,既保持了边缘又抑制了噪声,取得了更好的去卷积效果．     

预应力钢板箍与CFRP复合加固RC墩柱轴压性能试验研究

提出一种新型的采用预应力钢板箍(PSJ)和碳纤维布(CFRP)复合加固钢筋混凝土(RC)墩柱加固方法(简称PSJ-CFRP)。为验证该新型加固技术的可行性和有效性,进行了8个足尺圆形墩柱轴压性能试验,研究参数包括不同加固方法(PSJ、CFRP和PSJ-CFRP)、钢板箍预应力水平、PSJ与CFRP加固配箍特征值等,比较分析采用不同加固方式加固试件的加固效果、破坏形态和承载力等,研究了PSJ-CFRP复合加固RC墩柱的受压机理,钢板箍预应力度、PSJ与CFRP加固配箍特征值等关键参数对试件轴压性能的影响和规律。试验结果验证了PSJ-CFRP复合加固技术的有效性,CFRP与钢板箍协同工作、优势互补,既提高了试件的承载能力,又改善了试件的变形性能,加固试件呈现延性破坏特征。采用CFRP加固的试件,试件的承载能力得到提高,但变形能力降低,呈现脆性的破坏特征。在相同加固配箍特征值下,减小加固箍板净间距能取得更好的加固效果。在试验和理论分析的基础上,提出了PSJ-CFRP复合加固RC墩柱轴向受压承载力计算公式,能较好地预测加固墩柱的轴心受压承载力。     

土基压应变敏感性分析

路表弯沉并不能完全反映土基顶面压应变,在路面结构设计中必需要重视土基顶面压应变的状态。鉴于此,采用典型路面结构,分析各结构层参数的变化对土基顶面压应变和土基内部压应变的影响,以为沥青路面结构设计提供参考。     

The implications of MARPOL Annex V on the management of ports and coastal communities

Abstract

The passage of the Marine Plastics Pollution Research and Control Act of 1987 (MPPRCA), which codified Annex V of the International Convention for the Prevention of Pollution from Ships (MARPOL), has encompassed every commercial and recreational shipping and boating facility in the United States. As a group, these ports, harbors, and marinas form a significant, although proportionately small, portion of the coastline of the country. More important, the economic benefits derived from the complex shoreside infrastructures required for international ocean trade, commercial and recreational fishing, and pleasure boating indicate just how critical it is for these facilities to be in conformance with effective and prudent coastal zone and environmental management practices.     

考虑沥青路面材料参数空间差异性的解析计算及影响分析

复杂服役环境下沥青路面的材料参数存在明显的空间差异性，具体表现为沿深度的模量梯度分布与非连续层间接触以及横观各向同性，实现其解析计算对现有的沥青路面力学响应分析及结构设计方法具有重要的参考价值。为此，从弹性力学基本方程出发，基于状态空间法，推导了具有指数模量梯度的横观各向同性弹性层状体系通解；在此基础上，基于波传递方法，将状态向量转换为波向量，并结合边界条件和层间条件，建立了考虑沥青路面材料参数差异性的多层路面结构解析解；然后借助MATLAB平台编制了数值计算程序，采用文献对比、BISAR程序以及有限元软件ABAQUS验证了该解析解的精度与效率；最后结合典型数值算例，阐述了该解析解在沥青Top-Down开裂和传统路面疲劳损伤分析中的应用。理论推导和数值计算结果表明：该解析解摆脱了弹性力学问题求解对应力函数的依赖性，并且借助波传播方法，避免了求解中正指数过大对求解精度的影响，并使得边界条件和不同层间接触关系的描述更加便捷；沥青路面材料参数的空间差异性不可忽视，沥青面层连续模量梯度会造成更大的路表拉应力和最大剪应力，进而加剧沥青路面的Top-Down开裂；而横观各向同性和层间接触状态间存在耦合效应，从而会加剧沥青路面的疲劳损伤。     

货车用新型工程塑料心盘衬垫的研究

铁路机车车辆上下心盘的磨耗，是机车车辆一惯性质量问题。解决此问题的有效方法是在上下心盘间配置新型工程塑料制成的车辆心盘衬垫。文章从原因分析入手，解决了理论计算与实际使用中受力的差异，弄清了车辆心盘衬垫在运行状态下受纵向、横向、扭力及动载加速度等因素影响时与材质物性间的关系，从而确立了合理选材、配方设计、结构设计的科学方案。     

土工液塑限试验中的新方法应用与比较

针对公路与水电土工试验规程中所采用的作图法确定液塑限值而带来的诸多不便,采用数学解析法、最小二乘法、回归分析法计算液塑限试验数据,并将其编制成QBASIC程序上机处理,由此确定出的液限、塑限值较传统方法方便、快捷、准确。同时对公路与水电土工试验规程中所采用的不同圆锥下沉深度而计算出的液塑限值进行了比较。     

A Note on Shor''s Quantum Algorithm

Shor proposed a polynomial time algorithm for computing the order of one element in a multiplicative group using a quantum computer. Based on Miller's randomization, he then gave a factorization algorithm. But the algorithm has two shortcomings, the order must be even and the output might be a trivial factor. Actually, these drawbacks can be overcome if the number is an RSA modulus. Applying the special structure of the RSA modulus,an algorithm is presented to overcome the two shortcomings. The new algorithm improves Shor's algorithm for factoring RSA modulus. The cost of the factorization algorithm almost depends on the calculation of the order of 2 in the multiplication group.     

The effect of plastic constraint on the initiation of ductile tears in shipbuilding structural steels

In this paper, the effect of plastic constraint on the initiation of ductile tears in four different shipbuilding structural steels has been experimentally studied by measuring the J-integral and crack opening displacement COD at initiation in three-point bend specimens with deep and shallow notches. Experimental results of seven groups of different strength alloy steels show that both Si and Ji values of ductile tear from the shallow crack specimens which have less constraint flow field are significantly higher than those of deeply notched specimens. Slip-line-field analysis shows that, for shallow crack, the hydrostatic stress is lower than that from standard deeply cracked bend specimen, which develops a high level of crack tip constraint, provides a lower bound estimate of toughness, and will ensure an unduly conservative approach when applied to structural defects, especially if initiation values of COD and J-integral are used.