Measurements of threshold values for incipient motion of sediment particles with two different erosion devices

For studies on sediment transport processes experimental data on the erosion behaviour of sediments are necessary. Because of significant differences in experimental setups and subsequently in resulting values comparisons and, where possible, correlations between methods are required. This study presents measurements with two different erosion devices (straight flume and microcosm erosion chamber), which were used for the determination of critical shear stress velocities for sandy submarine sediments and sieved sediment fractions. An approach is presented to convert measured current velocities into shear stress velocities via roughness length values and drag coefficients under hydrodynamically smooth and transitional turbulent flow conditions. The results from both devices show a good agreement and the measured erosion threshold values fit to established correlations between critical shear stress velocity and grain size. In the grain size range below 200 µm results for naturally composed sediments are influenced by effects caused by the silt- and clay fraction. Sieved sediment fractions in this grain size range tend to show lowered erosion thresholds in relation to the Shields' curve.     

青藏公路昆仑山口至五道梁段主要水害问题及水文地质机理

青藏公路长期处于高寒、恶劣的特殊环境中,以水害（冻土）为主要特征的各种路基病害频繁发生。对青藏公路主要路基病害中的水害问题进行了调查,在昆仑山口至五道梁段,选取典型水害分布点,从水文地质角度出发,总结了青藏公路的主要公路水害问题,分析了引起相应水害问题的水文地质机理。     

基于特定任务域的自然语言生成系统实现方法

针对自然语言生成系统在任务域不同时需要对系统进行重新设计的问题,本文从可移植的角度,对自然语言生成系统中的任务域处理模块、语言学处理模块、文本生成模块进行了研究,提出了一种基于特定任务域具有可移植的自然语言生成系统的实现方法,并通过实验验证了该方法的可行性.     

Seaport investments in capacity and natural disaster prevention

Most seaports face constraints in financial resources to some degree, and thus need to balance the investments in capacity and natural disaster prevention. On the one hand, due to budget constraint, limited resources need to be allocated between the two tasks. On the other hand, the benefit of natural disaster prevention investment is likely to be higher for ports with larger capacity. This study builds a stylized analytical model to examine the managerial and policy implications of such interactions between the two counteracting mechanisms. We find that the port managers would always prioritize capacity investment over natural disaster prevention investment. Social welfare maximizing ports invest more in both capacity and disaster prevention than those chosen by profit maximizing operators. However, compared with profit maximizing ports, welfare maximizing ports also require a larger budget to justify the investment in disaster prevention. Moreover, with increasing intensity of natural disaster, a port’s capacity investment decreases and its disaster prevention investment increases, irrespective of its objective. The magnitudes of both changes are larger for welfare maximizing ports than for profit maximizing ports.     

天然气/柴油双燃料发动机电控喷气技术研究

本文研制开发了天然气／柴油双燃料发动机的压缩天然气（ＣＮＧ）电控喷气系统。试验表明，电控喷气可以明显改善双燃料发动机的燃料经济性和排放性能，提高发动机的热效率。合理选择加载喷射压力和喷射相位可有效地提高燃烧速度和燃烧稳定性。     

公路灾害应急管理方案研究

文章阐述了公路灾害对道路网的影响,并针对宁波市江北区公路桥面结冰、下穿道积水及水毁灾害的特点,分析了公路灾害应急管理所存在的关键问题,提出了相应的应急管理方案。     

弹性基础上复合材料层合剪切板的自由振动和动力响应

基于Reddy高阶剪切变形板理论及由Shen导得的广义Karman型方程,用双重Fourier级数展开法求得弹性基础上四边简支对称正交铺设和反对称斜交铺设层合剪切板在预加面内荷载作用下的自由振动及在横向动荷载共同作用下动力响应的解析解,并讨论了基础弹性常数和预加面内荷载对固有频率及动力响应的影响。     

自然风对高速磁浮列车气动特性的影响

基于可压缩黏性流体的N—S方程和k—ε两方程湍流模型,采用有限容积法对磁浮列车受自然风作用下的气动力特性进行计算分析,结果表明:自然风导致列车表面的压力分布发生变化,除了列车头、尾部压力峰值点发生偏移外,列车迎风侧面的压力随着自然风速的增加而增大,随着自然风与列车之间夹角的增大呈现先增大后减小的变化规律;列车受到气动升力、侧向力以及侧滚力矩、俯仰力矩和偏转力矩的作用也随着自然风与列车之间夹角的增大呈先增大后减小的变化规律,且在自然风向与列车运行方向垂直时达到最大,此时列车受到的气动力及力矩作用均随自然风速的增大而单调增加。     

西部地区未铺路面道路的病害与防治

通过采用化学加固法、碎石封层、改变道路几何形状等措施来降低道路病害,提高通行能力,对未铺路面道路的设计与养护具有一定的指导意义.     

VARIABLE CUTOFF FREQUENCY NONLINEAR DIGITAL FILTERS: I-ONE-DIMENSION

ＶＡＲＩＡＢＬＥＣＵＴＯＦＦＦＲＥＱＵＥＮＣＹＮＯＮＬＩＮＥＡＲＤＩＧＩＴＡＬＦＩＬＴＥＲＳ：Ｉ－ＯＮＥ┐ＤＩＭＥＮＳＩＯＮ＊ＧｕＨｏｎｇ（古红）ＺｈｕＹｉｓｈｅｎｇ（朱贻盛）（ＩｎｓｔｉｔｕｔｅｏｆＢｉｏｍｅｄｉｃａｌＥｎｇｉｎｅｅｒｉｎｇ，Ｓｈａ...