悬板分层式引水渠首悬板区水力特性研究

本研究对悬板分层式引水渠首悬板区的水力特性进行了系统的研究，并分析了其对输沙的影响，为进一步研究整个引水渠首的水力特性及输沙机理打下了基础。对悬板前缘采用流线堰和皮氏堰的优劣进行了对比研究，得出流线堰优于皮氏堰的结论。     

悬板区流场测试分析

通过悬板分层式引水渠首所谓皮卡洛夫堰以线堰两种不同堰型水力要素的测试，分析了现任中堰型悬板上下层分流量，流速分布、水面线及流太，在此基础上对两种悬板缘头型式作了分析比较。对上核定上堰型现行过流能力的计算方法提出了异议。     

天然气输差问题及其解决方法

天然气输差是燃气公司一个重要的经济指标。分析了产生天然气输差的原因，对标准孔板引起的测量误差、输气干线测量误差和测量误差造成的输差进行了计算，给出了单点输差和综合输差的计算方法，提出了降低输差的措施和方法。     

悬板分层水流流动特性的测试研究

随着悬板分层式引水枢纽工程近年逐步被推广应用，对其水流特性及输沙机理的研究也越来越受到人们的重视。本研究利用激光测速仪首次对悬板分层水流流场特性进行了测试，并分析了其对输沙过程的影响     

悬板过流的二维势流数值模拟

本研究利用边界元法求角了悬板分层式引水渠道的悬板区过流问题，根据自由水面和泄流量迭代过程中相互影响的关系，提出了得同步迭代方法，计算表明，这种迭代方法对泄流量和自由表初值没有苛刻要求，同时具有较好的收敛性能，计算结果与实测结果吻合良好。     

寒冷地区输气管道站场保温设置模拟

中国寒冷地区输气管道站场日益增多,但对站场保温设置的重要性认识不足。为了保障站场运行安全,节约运行成本,开展了站场保温设置原则及必要性研究。通过模拟保温对停输管道温降的影响,分析了保温设置对维持管壁温度的效果;通过模拟保温对站内热损失的影响,分析了保温设置对节约运行成本的效果。研究结果表明:设置保温对维持停输后管壁温度、降低站内温降损失效果显著。提出以下原则:根据达到设计输量年限确定站场是否设置保温;加热设备选型需要充分考虑站内温降等工艺参数。该研究成果已在中国东北地区哈沈线、中俄东线等工程中应用,并可进一步指导后续同类工程的建设。     

悬栅消能工水力特性研究

通过对新型悬栅消能工流场的测试，揭示了悬栅流场的水流流态、流速分布、水面线形态和压力分布等水力特性。随着过水流量、悬栅栅条的设置高度，悬栅栅条的间距及悬栅栅条的断面形状的改变，其水力特性也随之发生变化，并直接影响着悬栅的消能效果。     

一种成品油长输管道板式带压堵漏的新方法

针对卡箍堵漏技术存在的缺点,通过采用新的工艺和工具对传统的长输管道带压堵漏方法进行改进,提出了一种成品油(汽、柴油)长输管道带压堵漏的新方法-链式紧固器快速压紧补强板方案.实践证明,该方法针对长输管道漏点和腐蚀裂缝进行带压堵漏,方便快捷、安全可靠.     

大跨悬索桥动力特性的敏感性分析

以四渡河悬索桥为研究背景,建立了该大跨钢桁架加劲梁悬索桥的空间动力计算模型,研究了土-桩-桥相互作用和中央扣的设置方式对大跨悬索桥动力特性的影响.结果表明,土-桩-桥相互作用对悬索桥动力特性的影响主要是以塔振动为主的频率减小;中央扣的设置使得悬索桥刚度有所增加,相应的各阶频率增大,但各类振型受影响的程度不同,其中反对称扭转振动频率和以纵飘振动为主的频率增加最为显著,并且刚性中央扣作用高于柔性中央扣.     

基于向量式有限元方法的长输海底管道不平整度分析

海管不平整度分析是悬跨海管设计、施工和运行维护过程中的重要环节。基于向量式有限元方法,提出了一种海管不平整度分析新方法。该方法采用UWAPIPE模型模拟管土耦合作用,采用基于区域分解的MPI并行技术以提高计算效率。对我国南海一段经过沙波区的海管进行不平整度分析,得到了海管位形、悬跨状态以及管道内弯矩分布,模拟结果与水下机器人(ROV)调查结果吻合良好。在此基础上,基于大量悬跨数据的统计分析,给出了不同工况对悬跨长度和高度的影响。模拟了危险悬跨海管开挖治理后的状态,结果表明开挖治理不仅能够有效消除悬跨,同时能够大大减小管道内弯矩分布。相关方法可用于海底长输管道的安全预警。     

陕西渭河流域水沙动态变化对环境的响应

根据1954～1996年的降水、径流和泥沙等方面资料,对陕西省渭河流域的水沙动态变化进行统计分析,并对水沙变化的主要原因进行探讨,进而揭示水沙变化对环境因素的响应关系。结果表明,渭河流域水沙输送主要集中于降水量较大的汛期,年内分布相对集中;年际变化较大,从20世纪50年代到90年代总体均呈下降趋势;流域径流量、输沙量与环境要素之间存在密切的响应关系。     

立轴式脱粒机研究

针对南方丘陵稻麦两熟地区分段收获机械化的需要,研制出立轴式脱粒机,该机以一根立轴联接螺旋板齿脱粒滚筒、上排杂风扇和下轴流风扇,并驱动其旋转,同时,采用二次切割喂入装置。试验表明,该机脱净率高、破碎率低、结构紧凑,但脱稻的含杂率较高。     

基于次降雨条件下的武水流域径流输沙规律研究

流域径流输沙规律反映区域水土保持与生态环境状况,可指导区域水土流失治理与生态建设。流域径流与输沙受降雨、下垫面因素及流域综合环境要素的影响。在对湖南武水流域径流与泥沙输移影响因子分析的基础上,基于次降雨与对应次径流、次输沙（包括悬移质与推移质）实测资料,建立武水流域次降雨条件下的径流与输沙经验回归模型,可用于流域径流与输沙预测预报。     

Recent sedimentation on the new jersey slope and rise

Radiocarbon dating and sedimentological studies of closely spaced cores indicate movement during the Holocene of sediments on the New Jersey continental slope and upper rise between Wilmington and Lindenkohl canyons. The uneven time-stratigraphic thickness of the late Quaternary sediment sections between cores and the nonuniform deposition rate at any given core site and among core sites show that the sediment blanket in canyon and intercanyon areas has been affected by downslope, gravity-driven pocesses during the Holocene to the present. The reduced rate of deposition on the slope and upper rise between the late Pleistocene and the present is largely due to decreased off-shelf transport in response to the eustatic rise in sea level. Very old radiocarbon dates at core tops result from emplacement of older reworked materials from upslope or from truncation of sections by mass wasting processes exposing older material at the sea floor. These processes also account for an irregular sequence of dated sections within cores and stratigraphic irregularities of the surficial cover from core to core. Marked variability in deposition rates on the slope and upper rise is largely a function of topographic configuration, proximity and accessibility to sediment source, and transport processes seaward of the shelf break. Moreover, higher accumulation rates on the upper rise are attributed primarily to slope bypassing. Bypassing, prevalent during the late Pleistocene, has continued periodically to the present.     

土地利用/覆被变化下流域泥沙输移的分形特征及尺度转换

基于由WEPP模型提取的甘肃天水罗玉沟和吕二沟小流域单元侵蚀产沙及泥沙输移资料,采用分形维数理论,对流域泥沙输移比的空间分异规律、泥沙输移比的影响因子以及泥沙输移的尺度转换进行研究。结果表明:年均泥沙输移比有相当大的变幅,不同流域尺度上的泥沙输移比为0.03～1.00,对于一定尺度的流域,泥沙输移比是一个比较稳定的值;小流域泥沙输移过程具有分形特征;根据研究区流域泥沙输移比的分形特征,综合其他地区的研究结果,建立了小流域泥沙输移比尺度转换模型,同时建立了研究区适用尺度范围更广的流域泥沙输移比尺度转换模型。     

Transport capacity models for unsteady and non-equilibrium sediment transport in alluvial channels

This study investigates transport capacity models based on different dominant variables-shear stress, stream power, unit stream power, flow discharge, flow velocity, and energy slope – in a model of unsteady and non-equilibrium sediment transport in alluvial channels. The model simulates fully coupled system of water flow, suspended sediment, and bed load sediment transport processes in two-layer system of water flow phase and movable bed. The model employs conservation of mass equation for the water in both the layers; suspended sediment in the water flow phase; sediment in the movable bed layer; and the momentum equation for the water flow in the flow phase. The system is closed by relating the sediment flux in the movable bed layer to the sediment concentration in the same layer by employing the kinematic wave theory. Using the sediment transport capacity expression with different dominant variables, a series of numerical experiments are carried out for unsteady and non-equilibrium sediment transport. The results seem theoretically reasonable for hypothetical cases. The model is calibrated and validated using different experimental data sets. The calibrated value for the transport capacity model’s exponent (k_i) is found to be 1.50, 1.65, 0.24, 0.56, 4.80, and 0.22 for shear stress, stream power, unit stream power, discharge, velocity, and slope approaches, respectively. The numerical investigation results show that transport capacity model based on any dominant variable can be employed for modelling unsteady and non-equilibrium sediment transport.     

Formation of the rocky mountains, Western United States: a continuum computer model

One hypothesis for the information of the Rocky Mountain structures in late Cretaceous through Eocene time is that plate of oceanic lithosphere was underthrust horizontally along the base of the North American lithosphere. The horizontal components of the motion of this plate are known from paleomagnetism, and the edge of the region of flat slab can estimated from reconstructed patterns of volcanism. New techniques of finite-element modeling allow prediction of the thermal and mechanical effects of horizontal subduction on the North American plate. A model that has a realistic temperature-dependent rheology and a simple plane-layered initial condition is used to compute the consequences of horizontal underthrusting in the time interval 75 million to 30 million years before present. Successful prediction of this model include (i) the location, amount, and direction of horizontal shortening that has been inferred from Laramide structures; (ii) massive transport of lower crust from southwest to northeast; (iii) the location and timing of the subsequent extension in metamorphic core complexes and the Rio Grande rift; and (iv) the total area eventually involved in Basin-and-Range style extension. In a broad sense, this model has predicted the belt of Laramide structures, the transport of crust from the coastal region to the continental interior, the subsequent extension in metamorphic core complexes and the Rio Grande rift, and the geographic region of late Tertiary Basin-and-Range extension. Its principal defects are that (i) many events are predicted about 5 million to 10 million years too late and (ii) the wave of crustal thickening does not travel far enough to the east. Reasonable modifications to the oceanic plate kinematics and rheologies that were assumed may correct these defects. The correspondence of model predictions to actual geology is already sufficiently close to show that the hypothesis that horizontal subduction caused the Laramide orogeny is probably correct. The Rocky Mountain thrust and reverse faults formed in an environment of east-west to northeast-southwest compressive stress that was caused by the viscous coupling between the oceanic plate and the base of the North American crust. Nonuniform crustal thickening by simple-shear transport also caused relative uplifts; therefore, this model is consistent with both of the range-forming mechanisms that have been inferred (1). A new proposal that arises from this simulation is that horizontal subduction also caused the subsequent extensional Basin-and-Range taphrogeny by stripping away the mantle lithosphere so that the crust was exposed to hot asthenosphere after the oceanic slab dropped away.     

Diphenylhydantoin: effects on calcium metabolism in the chick

Rickets, hypocalcemia, decreased duodenal calcium transport, and reduction of calcium binding protein have been produced in chicks treated with diphenylhydantoin. These effects are directly related to diphenylhydantoin dose and inversely related to the intake of vitamin D(3) (cholecalciferol).     

Impact of humans on the flux of terrestrial sediment to the global coastal ocean

Here we provide global estimates of the seasonal flux of sediment, on a river-by-river basis, under modern and prehuman conditions. Humans have simultaneously increased the sediment transport by global rivers through soil erosion (by 2.3 +/- 0.6 billion metric tons per year), yet reduced the flux of sediment reaching the world's coasts (by 1.4 +/- 0.3 billion metric tons per year) because of retention within reservoirs. Over 100 billion metric tons of sediment and 1 to 3 billion metric tons of carbon are now sequestered in reservoirs constructed largely within the past 50 years. African and Asian rivers carry a greatly reduced sediment load; Indonesian rivers deliver much more sediment to coastal areas.     

天山北坡河流的数学地貌特征及河流产沙分析初探

本文应用数学地貌方法对天山北坡五条河流建立了流域地貌数学模型。通过区域地质地貌及河流水文资料的分析,确立了它们之间的内在联系,并对人们关心的河流产沙问题进行分析。本方法对于干旱内陆区地形变化大,岩性复杂的天山地区是适用的。河流的产沙与河流流域地貌数学特征及发育阶段相对应,又与地层岩性、降水量、植被等有关。穿过有大面积中生界和第三系地层出露地区的河流,其含沙量高,侵蚀模数大。另外在新构造运动强烈地区的流域地貌数学特征值:河流比降,地形高程曲线积分值大,河流侵蚀搬运力强。