基于分形理论的黄河内蒙古段河势演变特征及其与凌汛灾害关联研究

寒区河道凌汛灾害河势“弯道效应”的量化评估十分重要。基于分形理论提出河道横断面-纵剖面-平面多维度河势分形维数计算方法及其物理机制，并探讨黄河内蒙古段不同维度河势演变分形特征及其与凌汛灾害的关联关系。结果表明，黄河内蒙古段不同维度河势均具有多尺度自相似分形特征，且具有多年记忆周期的长程相关性；冰坝（严重性冰塞）发生频次与河道主槽弯曲分形维数呈正相关指数型函数关系，与河相系数、深泓点高程和河段平均底坡分形维数负相关，与水深-面积分形维数正相关，总体表明冰坝灾害更易发生于主槽偏移摆动大、蜿蜒曲折、河湾发育程度高的宽浅型弯曲河道，研究成果可为凌汛期冰塞冰坝灾害易发河段诊断及预测提供重要理论依据。     

Relationship between adjustment of low water level and utilization of water depth in Shashi Reach in middle Yangtze River

Hydrological, sediment, and bathymetric data of the Shashi Reach in the middle Yangtze River for the period of 1975–2018 were collected, and the characteristics of low water level changes and their impacts on utilization of water depth for navigation were investigated. The results showed that, during the study period, the Shashi Reach riverbed was significantly scoured and incised, with cross-sectional profiles showing overall narrowing and deepening. This indicated a strong potential to improve the water depth of the channel. The analysis of the temporal variation of in-channel topographical features showed that the Taipingkou diara underwent siltation and erosion, with its head gradually scoured and relocated downstream after 2008, and the Sanbatan diara continued to shrink and migrate leftwards. Low water levels with the same flow rate over the study period decreased. For instance, from 2003 to 2020, the water level at the Shashi hydrological station decreased to 1.37 m with a flow rate of 6 000 m³/s. Furthermore, the designed minimum navigable water level of the Shashi Reach was approximately 2.11 m lower than the recommended level. In terms of utilization of the channel water depth, continuous scouring of the river channel is expected to result in a reduction in discharge at the Taipingkou mouth, which will improve the water depth conditions of the channel during the dry season in the Shashi Reach. With several channel regulation projects, the 3.5-m depth of the Shashi Reach would basically be unobstructed. This promotes utilization of the shipping route from the Taipingkou south branch to the Sanbatan north branch as the main navigation channel during the dry season. Considering the factors of current water depth and the clear width limitation of the navigation hole at the Jingzhou Yangtze River Bridge, this route can still be favored as the main navigation channel with a 4.5-m depth during the dry season.     

A computerized potentiometric system for structural and functional anthropometric measurements

A prototype computerized potentiometric system was developed for structural and functional anthropometric measurements. The system uses four potentiometric units, a power supply unit, and a computer with analogue/digital (A/D) converter to measure the position of a movable stylus in three (X, Y, Z) dimensions. The system is easy to use, more accurate, and more cost effective than other existing systems. It has been found to be accurate for the intended application, faster than the manual methods available, and much less expensive than the photographic and opto-electronic systems currently available. For use in the industrial setting, a portable version of the system is envisaged in the future.     

Determination of worker physiological cost in workspace reach envelopes

Oxygen uptake (VO₂), heart rate (HR) and myoelectric activity (EMG) were measured while performing a repetitive task in the normal, maximum and extreme workspace reach envelopes. The VO₂ and HR increased significantly from the normal to the maximum to the extreme workspace reach envelope. The average increases in VO₂ when compared to the normal workspace were 19 and 52%, respectively. The corresponding average increases in HR were 6 and 14%, respectively. The increase in EMG for anterior deltoid, upper trapezious and erector spinae showed a significant increase from normal to maximum and from maximum to extreme workspaces. The average increases in EMG for anterior deltoid, upper trapezious and erector spinae, compared to the normal workspace were 96, 37 and 48% respectively for the maximum workspace and 193, 95 and 106% for the extreme workspace, respectively. The research indicated for the first time that during task performance, worker physiological cost would increase significantly with the increase in workspace reach levels.     

EFFECT OF DRILLPIPE ROTATION ON BOREHOLE CLEANING FOR EXTENDED REACH WELL

Wellbore cleaning is a key technology for the Extended Reach Drilling (ERD). The success of drilling extended reach wells depends directly upon the quality of wellbore cleaning. The rotation of the drillpipe, and hydraulic and rheological parameters, are the key factors for wellbore cleaning. In this study, Computational Fluid Dynamics (CFD) is applied to simulate solid-liquid two-phase flows in wellbore annulus. The annual flow field with the presence of drillpipe rotation is described through analyzing various rotation conditions. The results indicate that the quasi-spiral flow is the main flow pattern for liquid-solid transport in the horizontal annulus. The influence of rotation on the cuttings transport is also investigated, as the rotation of drillpipe increases the disturbance of liquid to solid in annulus. As a result, the solid flow becomes favorable and the solid volume is reduced. Comparisons with previously published results are also performed to prove the importance of drillpipe rotation in the wellbore clearing for the ERD.     

浔江防洪堤对西江中下游洪水的归槽影响

基于河道洪水演算原理,建立符合河流水力特性及其变化规律的边滩滞洪水库调节法流量演算模型、校正因数法水位演算模型,利用实测洪水和防洪堤资料进行归槽或还原演算,综合分析防洪堤对洪水归槽的影响。保护区滞洪容积占次洪水总量9．50％的浔江防洪堤对西江中下游洪水过程的归槽影响大于对洪峰的归槽影响,而且洪水类型和干支流组合不同,影响的程度也不相同：对流量过程、洪峰流量影响的最大归槽流量、最大归槽流量比重分别为3680m^3／s、9．63％,2700m^3／s、5．90％,对水位过程、洪峰水位影响的最大变幅为0．60、0．22m。浔江防洪堤造成的洪水归槽并未显著改变西江中下游洪水特性,干支流洪水遭遇、区间降雨和雨洪重叠仍然是形成西江中下游大洪水的主要因素,西江中下游洪涝频繁是气候和流域环境变化综合影响的结果。     

广州港南沙港区附近水动力环境情景模拟分析

广州港南沙港区处于蕉门、虎门下泄流与伶仃洋上溯潮流的交汇区,港区水动力环境十分复杂.近年来鸡抱沙围垦工程进展迅速,港区附近陆域边界、水动力环境都在不断发生着变化.为了分析这种变化对南沙港区维护的利弊,主要采用数学模型动态情景模拟手段,分析了现状及鸡抱沙尾部下延对南沙港区的影响,针对水动力条件的变化,提出了减轻港池泥沙回淤的一些措施.     

成都市锦江华阳段趸船工程影响河道行洪的模型试验

为了解趸船工程影响河道行洪的情况,以成都市锦江华阳段的趸船工程为例,对该趸船工程所在河道进行了概化,利用物理模型试验研究了趸船工程对河段水流流态、水位及流速分布的影响。结果表明,该趸船工程虽对局部河段的流态、水位和流速等均产生一定影响,且随来水流量的增加壅水影响范围逐渐加大,但其自身对河道的行洪影响程度,总体上来说较小。     

长江石首河段航道整治工程行洪影响研究

分析了长江石首河段航道整治一期工程河段近期河床演变特点及演变趋势,采用平面二维水流数学模型计算分析了工程对河道水位及流场等的影响,并综合分析了工程对河势和行洪的影响。研究结果表明：拟建工程实施后不会对该河段行洪及河势产生明显的不利影响,但局部河势仍会有一定的调整。该研究成果可为航道整治工程设计提供科学依据。     

长江南京新济洲河段河道整治方案研究

在分析长江南京新济洲河段近期河道演变规律的基础上,提出河段在防洪、岸线利用、河势稳定等方面存在的主要问题。针对两岸经济发展的要求,提出两套整治方案,运用数学模型和物理模型相结合的手段,对整治方案进行了比选、优化,并提出了可行的推荐方案,使其有利于该河段及下游河段河势稳定及防洪安全。