水运对中国经济贡献率测算研究

以经济学中的产业波及理论模型为基础,运用投入产出法对水运行业的感应力系数和影响力系数进行了测算,同时测算并分析了水运业对中国经济、投资、就业的综合贡献率,较为全面地阐述了水运业对中国经济的影响,客观地提出了水运业对中国经济发展的作用和存在的问题。     

S变换在水下目标识别中的应用

研究了基于S变换模时频矩阵相似度的水下目标识别方法。根据测试样本对应的S变换模时频矩阵与标准样本对应的S变换模时频矩阵之间的相似度最大原则对测试样本进行识别。该方法不需要辅助分类器而直接实现目标识别,计算简单快速。仿真实验表明,该方法的识别率较高,且受噪声影响小,适合于水下目标识别。     

岷江上游大型水电站运行对龙溪口下游航道枯水期水位和流量的影响

根据规划,岷江龙溪口—宜宾段将通过航道整治达到内河Ⅲ级航道标准.该河段多年历时保证率95％的流量仅能达到662 m3/s,但是岷江上游紫坪铺、瀑布沟等大型水电站的建成对下游河段通航流量产生了较大影响.根据紫坪铺水电站蓄水前、后高场水文站的径流、泥沙资料,分析紫坪铺等大型水电站建成后对下游河段水沙特性的影响,得知岷江上游...     

通过三峡升船机的船舶排水量校验技术

受三峡升船机船厢结构强度的限制以及防止船舶发生触底,通过升船机的船舶排水量不能超过3 000 t,但目前行业内暂无相应的船舶排水量快速校验方法。通过分析不同类型船舶三维尺度与排水量的对应关系,以船舶方形系数为关键点,得出快速计算船舶总排水量的经验公式,并通过实例验证,从而提出校验三峡过坝船舶排水量的校验方法。结果表明,船舶排水量计算经验公式精度符合要求,提出的校验方法快速、准确。     

取样剪切对管输原油流变性的影响

通过实验及理论分析,系统研究了取样剪切对管输原油流变性的影响,根据鲁宁线运行工况,计算了阀门节流剪切及过泵剪切时剪切率的大小.对于鲁宁线,在同一泵站,出站处阀门节流平均剪切率是过泵平均剪切率的3倍左右.     

Corrosion rate measurements in steel sheet pile walls in a marine environment

Corrosion of steel structures in the marine environment is a major problem. The deterioration of this kind of structures is costly and difficult to predict both when designing new structures and when estimating the remaining service life time for existing structures. The aim of this investigation was to find indicative values for the corrosion rate of steel sheet piles on the Swedish west coast. Such corrosion rates (mm/year) can be used both when designing new structures by oversizing the steel thickness and when estimating the bearing capacity of existing sheet pile structures. Earlier investigations on the corrosion rates along the Swedish east coast – with salinity from about 0.2% to 0.8% – are still used today as guidelines for the corrosion rate of all steel structures in the Swedish maritime environment even though the salinity on the west coast can be as high as 3.0%.Steel sheet pile wharfs located in the port of Halmstad on the Swedish west coast were inspected by ultrasonic measurements. Three wharf structures with a total length of about 700 m were inspected. None of the inspected wharfs had or have had cathodic protection. The thickness measurements of the steel sheet pile structures were performed by divers.The age of the three inspected sheet pile structures ranged from 36 to 51 years. The dimensions of the original sheet pile sections are known. One of the quay structures is located along a river. The salinity at all wharfs varied from low values at the surface to approx. 2% at the bottom (also in the river outflow).The measured average corrosion rates were in the same order as the design values in the European code. However, the results indicate increased corrosion rates about 1 m below the mean water surface and at the level of the propellers from the ships berthing the most frequented of the inspected wharfs, 3–6 m below water surface.The tolerances of steel sheet thicknesses – usually in the order of ±6% – are often neglected when investigating the remaining thickness in steel sheet piles. A simple calculation model shows that the sheet pile must be almost 50 years of age before an accurate estimation on the corrosion rate can be made, considering the tolerances, if the true original sheet pile thickness is not known.     

沥青路面运营初期平整度竣工验收标准研究

采用数理统计原理,运用SPSS软件对陕西省7条高速公路交-竣工平整度数据进行分析,得出了陕南、关中和陕北地区路面平整度衰变幅度均值分别为0.39m/km、0.28m/km和0.24m/km,这也将作为计算竣工验收推荐值的依据;再基于交-竣工平整度变化规律,建立了平整度竣工验收推荐值的计算公式:IRIju=IRIji+IRIs,可为今后平整度竣工验收标准提供有效的理论依据。     

数控铣床加工低碳钢零件的进给速度优化

论述了数控铣床加工低碳钢零件时进给速度的优化问题．在基于加工效率（可等效转化为加工工时）和加工成本目标函数的基础上，对这两个目标函数运用多目标函数理论进行综合，得到了多目标综合函数．通过计算，并综合表面粗糙度，进而得到进给速度的优化范围，并对不同转速下的进给速度给出了相应的优化参数，目的更接近生产实际，使技术人员不仅了解影响生产效率和成本的因素，也可在实际生产的应用中更加快捷和方便．     

圆电极电磁流量计干标定模型及仿真

目前在电磁流量计的干标定研究中，为方便公式推导，通常将实际的圆电极简化为方电极模型．这种简化在电极尺寸较大时，会引入不必要的计算误差，影响流量计的标定精度．本文从圆电极模型出发，论述了其对应权重函数的计算过程．并针对大尺寸圆电极模型进行理想化计算，得到其点电极模型，并运用此模型进行了仿真研究．