森林植被改善对鄱阳湖流域径流和输沙过程的影响

以河流基流为切入点,研究流域植被调节径流、水土保持等微观作用影响大中型河流湖泊径流过程和水沙过程宏观效应的机理。鄱阳湖流域60年来天然降水没有发生趋势性变化。流域森林覆盖率由34.73%上升到63.00%,植被质量改善,赣江等入湖河流基流增加83 m~3/s,河流输沙量减少。2000年以后和2000年以前相比较,枯水期降水径流系数增大,年流量过程平坦化,一定程度上减小洪灾风险,有利于水资源利用和生态环境保护。2001年以后进入鄱阳湖泥沙平均每年减少1 007×10~4t;出湖泥沙增加314×10~4t。因此,鄱阳湖入江水道由淤积转变为冲刷,但出湖流量过程没有趋势性变化。     

墩头超长实用堰泄洪安全分析及模型试验验证——以缅甸DAPEIN(Ⅰ)水电站工程为例

以缅甸DAPEIN(Ⅰ)水电站工程为例,论述了将WES实用堰的闸墩墩头向上游超长延伸之后,对泄洪安全所造成的影响。针对WES实用堰流量系数、堰面动水压力容易受边界因子影响的特点,对设计断面的堰顶布置和墩头形状进行了优化。根据堰面空化数计算公式及水流特性推导出计算的关键部位,对空化数进行计算。采用几何比尺为1∶60的物理模型对溢流堰的泄流能力和堰面动水压力进行了试验测试。试验结果表明:溢流堰的模型试验泄流能力和设计泄流能力非常相近。堰面动水压力除工况2的B4测点出现了-1.2 k Pa的微小负压值外,其余堰面时均压强值均大于0。从而,在泄流能力和堰面动水压力两方面都验证了这种设计方案的合理性。该工程所遇到的结构布置问题在中低溢流坝工程中属常见问题,解决思路可为今后类似工程建设借鉴参考。     

Estimating discharge in gravel‐bed river using non‐contact ground‐penetrating and surface‐velocity radars

Discharge measurement is a critical task for gravel‐bed channels. Under high‐flow conditions, the elevation of the riverbed changes significantly by intensive torrential flow. The stage–discharge relations commonly used for stream discharge estimation may no longer be adequate. The contact‐type velocity measuring is also subject to measurement errors and/or instrument failures by the high‐flow velocities, driftwood, stumps, and debris. This study developed a new real‐time method to estimate river discharge in gravel‐bed channels. A systematic measuring technology combining ground‐penetrating radar and surface‐velocity radar was employed. The rating curves representing the relations of water surface velocity to the channel cross‐sectional mean velocity and flow area were established. Stream discharge was then deduced from the resulting mean velocity and flow area. The proposed method was examined in a steep gravel‐bed reach of the Cho‐Shui River in central Taiwan. The estimated stream discharge during three flood events were compared to the prediction by using the stage–discharge relation and the index‐velocity method. The proposed method of this study is capable of computing reasonable values of discharge for an entire flood hydrograph, whereas the other two methods tend to produce large extrapolation errors. Moreover, when the computed discharge is used in 2D flood flow simulation, the proposed method demonstrates better performance than the commonly used stage–discharge and index‐velocity methods.     

充填浮选柱捕集区气含率的试验研究

通过冷模试验方法考察了充填浮选柱捕集区的气含率，经试验数据回归分析，气含率εｇ＝０．０９６Ｊｇ０．９１（Ｈｃ／Ｄ）－０．１８。并结合漂移通量的理论，确定充填浮选柱的捕集区为近似均匀鼓泡流。     

Thermoelectric hydrogen sensor using Li x Ni1-x O synthesized by molten salt method

Li-doped NiO was synthesized by molten salt method. LiN_O3-LiOH flux was used as a source for Li doping. NiCl₂ was added to the molten Li flux and then processed to make the Li-doped NiO material. Li:Ni ratios were maintained from 5: 1 to 30: 1 during the synthetic procedure and the chemical compositions after characterization were found from Li_0.08Ni_0.92O to Li_0.16Ni_0.84O. Li doping did not change the basic cubic structural characteristics of NiO as evidenced by XRD studies; however, the lattice parameter decreased from 0.41769 nm in pure NiO to 0.41271 nm in Li_0.16Ni_0.84O. Hydrogen gas sensors were fabricated by using these materials as thick films on alumina substrates. The half surface of each sensor was coated with the Pt catalyst. The sensor, when exposed to the hydrogen gas blended in air, heated up the catalytic surface leaving the rest half surface (without catalyst) cold. The thermoelectric voltage thus built up along the hot and cold surface of the Li-doped NiO made the basis for detecting hydrogen gas. The linearity of the voltage signal vs H₂ concentration was checked up to 4% of H₂ in air (as higher concentrations above 4.65% are explosive in air) using Li_0.10Ni_0.90O as the sensor material. The response time T₉₀ and the recovery time RT90 were less than 25 sec. H₂ concentration from 0.5% to 4% showed a good linearity against voltage. There was minimum interference of other gases and hence H₂ gas can easily be detected.     

底吹钢包两相区两段模型

在考虑雷诺应力的基础上，建立了底吹钢包中气液两相区流体流动的两段模型。这一模型可用于计算近喷嘴处和浮羽流区各截面处两相流的平均速度、速度分布、流股直径和平均含气率等．数值计算表明：理论含气率与实验值符合很好．计算还表明：平均含气率和平均速度随高度的增大而减小，但流股直径随高度的增大而增大．另一方面，平均速度随初始供气量的增大而增大，而抽引比则随供气量增大而减小．通过两段模型可很好地描述喷嘴处气液流的行为．     

含CO2气体混合物在60℃时的混合性质

测定了６０℃和２－６００ｂａｒ时由ＣＯ２和Ｈｅ、Ａｒ、ＳＦ６以及ＣＨＦ３组成的等分子二元混合物的压缩因子，根据纯物质和混合物的压缩因子计算了压力混合效应和过剩体积。对于真实气体混合性质的描述，本文采用五参数的ＢＡＣＫ方程，方程计算值与实验值符合较好。     

热态下鼓泡浆液反应器的气含率研究

本文在热态条件下，研究了鼓泡浆液反应器的气含率、反应器直径为0.098m，物系组成为氮气－液体石腊－石英砂。考察了气速、压力、温度、静床高及固体引入等因素对气含率的影响。对于53μm粒子的三相浆态体系，气含率与表观气速关系式为εG=0.053uG^1.2。     

Polypyrrole composite membrane with high permeability prepared by interfacial polymerization

Novel polypyrrole (PPy)/polydimethylsiloxane (PDMS) composite membrane was prepared by interfacial polymerization to make a very effective gas separation membrane. We found that Polymerized PPy films as thin as ～200 nm could be chemically synthesized as freestanding membranes by using the interfacial polymerization technique. Additionally, we show that difference morphology of PPys films was obtained by controlling polymerization rate and more dense films were formed at low polymerization rate. Wide X-ray diffraction study showed the d spacing value of the PPy film decreased from 4.89 å to 3.67 å by the rate of polymerization decreases. According to d spacing value decrease, selectivity of a PPy composite membrane was increased dramatically and permeability was reduced gradually. This high selectivity was derived from d spacing closed to the kinetic diameter of nitrogen. These results indicated that the permeability is controlled by the diffusion coefficient, reflecting the packed structure of the PPy film. The highest selectivity value of composite membrane that was prepared by interfacial polymerization was O₂/N₂=17.2 and permeability for O₂ was 40.2 barrer.     

The role of pressure on thin amorphous carbon films deposited using microwave surface wave plasma CVD

We report the effects of gas composition pressure (GCP) on the optical, structural and electrical properties of thin amorphous carbon (a-C) films grown on p-type silicon and quartz substrates by microwave surface wave plasma chemical vapor deposition (MW SWP CVD). The films, deposited at various GCPs ranging from 50 to 110 Pa, were studied by UV/VIS/NIR spectroscopy, atomic force microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy and current–voltage characteristics. The optical band gap of the a-C film was tailored to a relatively high range, 2.3–2.6 eV by manipulating GCPs from 50 to 110 Pa. Also, spin density strongly depended on the band gap of the a-C films. Raman spectra showed qualitative structured changes due to sp³/sp² carbon bonding network. The surfaces of the films are found to be very smooth and uniform (RMS roughness < 0.5 nm). The photovoltaic measurements under light illumination (AM 1.5, 100 mW/cm²) show that short-circuit current density, open-circuit voltage, fill factor and photo-conversion efficiency of the film deposited at 50 Pa were 6.4 μA/cm², 126 mV, 0.164 and 1.4 × 10^− 4% respectively.