经营性公路合理回报测算方法研究

针对经营性公路项目的合理回报目前法律上没有明确规定,社会上各方认识不统一的问题,研究提出了经营性公路合理回报的衡量指标——合理收益率,明确了合理收益率的考核模式,并对确定的考核模式,给出了测算合理收益率区间上限和下限的具体方法。最后,运用提出的测算方法,借助于经营性高速公路项目进行了实证分析。根据研究结果,建议经营性高速公路项目的合理收益率上限值取lO．O％,下限值取相应年份的无风险收益率。测算结果为经营性高速公路项目的投资及行业收益监管提供了参考依据。     

钢管混凝土拱桥线型控制

结合某市钢管混凝土系杆拱桥的实际工况,通过钢管拱桥坐标测设、计算及钢管拱肋制作加工、采用临时支墩架设等施工工艺,对钢管拱桥拱肋施工线型控制进行了全面介绍,实践证明线型控制方法简单、方便、快捷,较好地处理了温度的不利影响。     

Evaluation,prioritization and selection of transportation investment projects in New York City

Over the last decade, a large number of high capital cost transportation projects have been proposed for the New York City Region. Many have resulted from addressing evolving capacity needs, changes in regional demographics and economics, meeting the improvements necessitated by operating century old subway systems and recognizing the impact of moving freight in a dense region. But the catalyst for bringing all of these projects to the attention of the public and all regional agencies was the tragedy of September 11, 2001. While these projects entail massive investments ($50–$60 billion), little analytical work has been carried out to measure the transportation and economic costs and benefits they entail and to categorize them accordingly. Competition among agencies to secure adequate resources to implement any of the desired projects makes such analysis necessary; yet there still remain political, vested economic interests and agency rivalry barriers to achieving this important planning objective. This paper reports the methodological approach taken by these authors for consistent and transparent project evaluation and then presents results from the ranking and prioritizing methodology. The policy underpinnings and implications of the analysis are discussed in a subsequent paper and thus only briefly touched upon here in the concluding section.     

Effects of surfactant on the growth of wind waves — Simultaneous observations with optical and microwave sensors

The growth of wind waves was investigated in a circulating tank over slick and “clean” surfaces. The slick surface was produced through the aging of seawater, and the “clean” surface was obtained by overflowing. Water-surface slopes and microwave backscattering were simultaneously measured with an optical slope gauge and a continuous-wave radar, respectively. Dependencies of the mean-square slope and the radar backscattered power on the wind-friction velocity over these two surfaces were found to be different. A delayed growth of ripples over the slick surface was identified from optical and microwave measurements. The suppression of ripples by surface slicks was most significant at low winds up to the wind-friction velocity of 15 cm s⁻¹. A reduction of −18 dB in the mean-square slope is found at the wind-friction velocity of 11 cm s⁻¹. The exponent of power-law dependence of radar cross section on wind-friction velocity over the slick surface was much larger than that over the “clean” surface. The radar backscattering from the slick surface was reduced by −40 dB at light winds and saturated at high winds with the wind-friction velocities smaller than 11 cm s⁻¹ and larger than 24 cm s⁻¹, respectively.     

斯里兰卡科伦坡临近海域波浪数值模拟

通过分析斯里兰卡科伦坡港口所处地理位置及气象波浪资料,了解工程海域主要受到季风气候的控制,冬季盛行东北季风,夏季西南季风,热带气旋在经过或影响到斯里兰卡岛时强度较低,风速不是很大,对该区域没有灾害性的影响。文章利用中尺度大气模式MM5模拟历史天气状态,再现1991~2010年20 a的影响工程海域的风场过程。根据得到的风场过程,利用海浪模式SWAN计算科伦坡南港附近海域30 m等深线处各向的波浪要素,并利用卫星观测数据进行结果验证。利用优化后的模型计算了1991~2010年计算方向的波高年极值,P-Ш曲线适线法计算得到不同重现期的外海波要素。     

从城区排涝洪峰流量计算分析内涝成因

当前城区排涝洪峰流量计算常用的公式主要有市政系统的雨水流量计算公式和水利系统的单位线法及推理公式法。该文通过工程实例,对几个公式的计算成果进行对比分析,推断城区内涝成因,可供类似工程参考。     

交通行为控制的对象及其特性分析

本文引入了交通行为控制的概念,明确其控制对象是交通中的人,以同交通系统控制区分开来.首先,借鉴行为科学、管理学和经济学中对人的研究方法,本文提出了以"交通人"的概念来承载交通行为控制对象的共性,明确了"交通人"的内涵与外延及其承载的有关人的性质的假设,并简单阐述了各项假设的意义;其次,通过探讨"交通人"与出行者的区别和...     

亮子河大桥水文计算

以营城子至抚民高速公路跨越亮子河为工程背景,通过洪水调查、理论分析,用经验公式及形态断面法,结合桥位处地形地貌,计算亮子河百年一遇流量、水位,推出亮子河大桥桥梁孔径及控制标高。     

OBF分解与BP网络在船舶磁场信号检测中的应用

针对水中兵器探测船舶磁场信号时信噪比较低的问题,提出了基于OBF分解与BP网络的船舶磁场信号检测算法。首先采用BP网络对测量数据进行预处理,滤除大部分环境磁噪声;再采用OBF分解算法对网络输出信号进行检测,提取归一化能量信号作为检验统计量。试验结果表明,本文算法可以显著提高信噪比,增强对船舶磁场信号的检测能力,性能明显...     

城市轨道交通杂散电流防护失效原因及新型防护方案研究

结合城市轨道交通工程杂散电流产生的根源及传输路径,对目前常规采用的防护方法效果不佳的原因进行分析.针对杂散电流产生的源头,提出在钢轨绝缘扣件处,扩大并长期持续保证其绝缘爬距有效性;针对杂散电流的传输,提出有效阻断其非预期传输路径的新思路及方案,包括双绝缘节及定向回流方案等;对杂散电流的泄漏总量进行有效控制,实现城市轨道...