整体叶盘根部与流道面分区域抛光技术

针对抛光整体叶盘根部与流道面工具损耗快、抛光效率低等问题,基于分区域抛光的思路从工具选型、轨迹优化、区域搭接及划分等方面开展研究。对抛光工具与轨迹进行优化;针对子区域之间的搭接问题建立优化模型并进行分析计算。在此基础上,基于分区域加工的方式对根部与流道面进行划分。工程环境下的抛光试验表明,分区域抛光将根部与流道面的工具损耗降低约30%,同时抛光效率提升约30%,从而推进了自动化抛光技术在整体叶盘上的工程化应用。

上冠流道面开槽的数控加工研究

介绍水轮机转轮模型上冠流道面配合槽的数控加工方法,指出上冠流道面配合槽的作用、加工难点和解决方法。使用三维区域清除的加工策略实现高速、安全的开粗加工,克服了粗加工中的碰撞和磨损刀具的现象,大幅提高了加工的效率。通过SWARF精加工策略,用驱动曲线控制产生高效、光顺、均匀的刀具路线轨迹,减少空走刀的数量,达到非常优化的加工;通过三维偏置精加工完成曲面的槽底,在实际加工中效果良好。

渣浆泵叶轮轴面流道的计算机辅助设计

随着计算机的普及及软件的发展 ,计算机辅助设计以其简便、快捷、准确而为广大设计工作者所接受 ,但在渣浆泵的叶轮轴面流道的绘制及校核中 ,大多以手工操作为主。本文给出了计算机编程所用的数学模型。

高流速泄洪洞流道混凝土过流面修补材料选择及应用

高流速泄洪洞对流道混凝土过流面质量要求非常高,但在施工过程中由于自然因素、施工条件或人为因素等的影响,混凝土表面难免存在缺陷瑕疵。为确保高流速水工隧洞运行安全,需对混凝土过流面缺陷进行修补处理。缺陷修补前,需积极筹划、提前研究确定处理方案,保证流道混凝土缺陷修补工作顺利开展和修补质量满足高流速水工隧洞运行要求。文章通过试验研究比选确定了适合高流速水工隧洞修补材料及其处理工艺,并通过溪洛渡水电站泄洪洞流道混凝土过流面处理的选用及泄洪过流验证,确定材料选取得当,工艺先进,处理效果总体优良,可供类似工程参考。

变截面质量叶片设计

针对矿用引风机叶片磨损快、寿命短、维修费用高的实际情况，从纵横两个剖面研究磨损机理，建立了横剖面的磨损公式。提出了变质量叶片。使用表明，变质量叶片使得叶轮的使用寿命提高了５倍左右，节约了大量的维修费用。

定型钢桁架拉模在安谷电站堰面混凝土施工中的应用

安谷电站泄洪冲砂闸工程闸底板采用开敞式有坎宽顶堰型,坡面为近似折线的曲面,在施工中保证堰面曲线精度是一个至关重要的问题,本文介绍定型钢桁架拉模在闸底板断面上的精度控制以及堰面50cm厚C40HF(W6)混凝土的施工工艺。

引风机叶片磨损机理的研究

针对矿用引风机叶片磨损快、寿命短、使用费用高的实际 ,从纵横两个剖面研究磨损机理 ,建立横剖面的磨损公式 。

Treatment of Domestic Sewage by Channels Constructed Wetland in New Countryside

[Objection] The aim was to study application of channels constructed wetland in treatment of domestic sewages in new countryside. [Method] Supported by construction of new rural areas project in China, we surveyed on new rural areas in Gannan, Jiangxi Province, summarized source, characteristics and treatment of domestic sewage in countryside, and designed channels constructed wetland for sewage treatment. [Result] The technique is proven effective in sewage treatment. After the technique was conducted for a trial run for four months, removal rates of COD, TP and TN averaged 73.07%, 73.25% and 72.36%, respectively. After contin- uous sampling for six times, effluent COD was analyzed 20-35 mg/L, TP was 0.60- 1.19 mg/L and TN was 6.88-11.21 mg/L, better than that of Standard 1B ruled by Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant. [Conclusion] Thanks for low investment, channels constructed wetland can be built by trans- formation of bottom land, proving a good way for treatment of diffuse pollution source and control of water non-point pollution.

The Theory of Field-Effect Transistors:XI. The Bipolar Electrochemical Currents(1-2-MOS-Gates on Thin-Thick Pure-Impure Base)

The field-effect transistor is inherently bipolar, having simultaneously electron and hole surface and volume channels and currents. The channels and currents are controlled by one or more externally applied transverse electric fields. It has been known as the unipolar field-effect transistor for 55-years since Shockley＇s 1952 invention,because the electron-current theory inevitably neglected the hole current from over-specified internal and boundary conditions, such as the electrical neutrality and the constant hole-electrochemical-potential, resulting in erroneous solutions of the internal and terminal electrical characteristics from the electron channel current alone, which are in gross error when the neglected hole current becomes comparable to the electron current, both in subthreshold and strong inversion. This report presents the general theory, that includes both electron and hole channels and currents. The rectangular （ x, y, z） parallelepiped transistors,uniform in the width direction （z-axis）,with one or two MOS gates on thin and thick,and pure and impure base, are used to illustrate the two-dimensional effects and the correct internal and boundary conditions for the electric and the electron and hole electrochemical potentials. Complete analytical equations of the DC current-voltage characteristics of four common MOS transistor structures are derived without over-specification： the 1-gate on semi-infinite-thick impure-base （the traditional bulk transistor）, the 1-gate on thin impure-silicon layer over oxide-insulated silicon bulk （SOI） ,the 1-gate on thin impure-silicon layer deposited on insulating glass （SOI TFT）, and the 2-gates on thin pure-base （FinFETs）.

一种曲线型Al-Si涂层数控车削加工方法

为提高曲线型带Al-Si涂层流道面轮廓度加工精度和表面光洁度,以Mastercam软件为平台,通过更改Mastercam软件后置处理程序中参数设置,选择合适刀具、优化数车加工参数,摸索出利用数控车床加工高精度曲线型带Al-Si涂层流道面的方案。

Multi-factor influence of cross-sectional airflow distribution in roadway with rough roof

The wall surface roughness renders a significant impact on ventilation of roadways and cross-sectional wind speed distribution.Herein,the wall roughness(Ra)in the roadway has been defined theoretically.Moreover,three-center arched roadway models for different situations are established based on the normal distribution of roof roughness.The influence of inlet velocity,roof roughness and roadway height on wind speed distribution is systematically studied by using Fluent software.At Ra=0.1 m,the simulation results reveal that the wind speed is negatively related to the distance from the wall to the point where 80%of the central wind speed is reached(DA).Also,the wind speed distribution is significantly influenced by increasing the roof roughness.However,the wind speed distribution becomes asymmetric at Ra=0.2 m and 0.3 m.Furthermore,the low-speed area(v≤1 m/s)started to concentrate on the roof with the increase of roadway height.Overall,an Ra value of<0.1 m can reduce the influence of wall roughness on wind speed distribution of the roadway,which is suggested in practical applications.

Nitrogen budget in the Changjiang River drainage area

We established a budget model of nitrogen （N） inputs and outputs between watersheds and waterbodies to determine the sources of riverine N in the Changjiang （Yangtze） River drainage area. Nitrogen inputs in the budget included N from synthetic fertilizer, biological fixation by leguminous and other crops, wet/dry atmospheric deposition, excreta from humans and animals, and crop residues. The total N input was estimated to be 17.6 Tg, of which 20% or 3.5 Tg N was transported into waterbodies. Of the total N transported into waterbodies, the largest proportion was N from animal waste （26%）, followed by N from atmospheric wet/dry deposition （25%）, synthetic fertilizer N （17%）, N in sewage wastes （17%）, N in human waste from rural areas （6%） and industrial wastewater N （9%）. We studied the spatial patterns of N inputs and outputs by dividing the Changjiang River drainage area into four sub-basins, from upstream to downstream： the Tongtian River drainage area （TTD, the headwater drainage area, 138 000 l^n2, less disturbed by human activities）; the Jinsha River drainage area （JSD, 347 000 km2, less disturbed by human activities, approx. 3 500 km upstream of the Changjiang estuary）; the Pingshan-Yichang drainage area （PYD, 520 500 krn2, large-scale human disturbance, about 2 000 km upstream of the Changjiang estuary）; and the Yichang-Datong drainage area （YDD, 699 900 km^2, large-scale httman disturbance, approx. 620 km upstream of the Changjiang estuary）. The average N input into waterbodies was 2.3, 7.3, 24.1, and 28.2 kg N/ha in the TTD, JSD, PYD, and YDD sub-basins, respectively, suggesting an increase of N-components of more than 10 times from upstream to downstream areas.

Stability and Drag Reduction in Transient Channel Flow of Fibre Suspension

Drag reduction features in the transition regime of channel flow with fibre suspension were analyzed in terms of the linear stability theory. The modified stability equation was obtained based on the slender-body theory and natural closure approximation. Results of the stability analysis show attenuating effects of fibre additives to the flow instability. For the cases leading to transition, drag reduction rate increases with the characteristic parameter H of fibres. The mechanism of drag reduction by fibres is revealed through the variation of velocity profile and the decrease of wall shear stress. The theoretical results are qualitatively consistent with some typical experiments.

Esophageal epithelial surface in patients with gastroesophageal reflux disease:An electron microscopic study

A/M： To investigate the intercellular spaces between the most superficially located esophageal epithelial cells in patients with gastroesophageal reflux disease （GERD）. METHODS： Eighteen patients with erosive esophagitis, 10 patients with non-erosive reflux disease （NERD）, and 18 normal asymptomatic volunteers were enrolled. Biopsy specimens were obtained from the lower esophageal mucosa without ulcer or erosion. Scanning electron microscopy was employed to investigate the tightness of the superficial cellular attachment. RESULTS： The intercellular space between the most superficially located epithelial cells in patients with erosive esophagitis or NERD was not different from that in asymptomatic healthy individuals. CONCLUSION： Widened luminal intercellular spaces of esophageal superficial epithelium are not responsible for the induction of reflux symptoms in patients with GERD.

Esophagogastric junction distensibility assessed using the functional lumen imaging probe

To assess reference values in the literature for esophageal distensibility and cross-sectional area in healthy and diseased subjects measured by the functional lumen imaging probe (FLIP).METHODSSystematic search and review of articles in Medline and Embase pertaining to the use of FLIP in the esophagus was conducted in accordance with the PRISMA guidelines. Cross-sectional area and distensibility at the esophagogastric junction (EGJ) were abstracted for normal subjects, achalasia, and gastroesophageal reflux disease (GERD) patients, stratified by balloon length and volume of inflation.RESULTSSix achalasia studies (n = 154), 3 GERD (n = 52), and 5 studies including healthy controls (n = 98) were included in the systematic review. Normative data varied widely amongst studies of healthy volunteers. In contrast, studies in achalasia patients uniformly demonstrated low point estimates in distensibility ≤ 1.6 mm2/mmHg prior to treatment that increased to ≥ 3.4 mm2/mmHg following treatment at 40mL bag volume. In GERD patients, distensibility fell to the range of untreated achalasia (≤ 2.85 mm2/mmHg) following fundoplication.CONCLUSIONFLIP may be a useful tool in assessment of treatment efficacy in achalasia. The drastic drop in EGJ distensibility after fundoplication suggests that FLIP measurements need to be interpreted in the context of esophageal body motility and highlights the importance of pre-operative screening for dysmotility. Future studies using standardized FLIP protocol and balloon size are needed.

Gas–liquid two-phase flow in serpentine microchannel with different wall wettability

Gas–liquid flow in serpentine microchannel with different surface properties exhibits drastically different flow behavior. With water and air as working fluids, the method of numerical simulation was adopted in this paper based on CLSVOF(coupled level set and volume of fluid method) multiphase model. After verifying the reasonability of the model through experiment, by changing wall properties and Re number(Re<1500), the influences of contact angle and surface roughness on flow regime and Po number were discussed. Moreover, the difference of pressure drop between curve and straight microchannel was also calculated. Beyond that, the combined effect of curve channel and wall properties on flow resistance was analyzed. This paper finds that wall properties have great influence on gas–liquid flow in microchannels not only on flow regime but also flow characteristics. Meanwhile, the pressure drop in curve microchannels is larger than straight. It is more beneficial for fluid flowing when the straight part of microchannel is hydrophilic smooth wall and curve part is hydrophobic with large roughness.

Interannual variability of transport and bifurcation of the North Equatorial Current in the tropical North Pacific Ocean

The relationship of the interannual variability of the transport and bifurcation latitude of the North Equatorial Current （NEC） to the E1 Nifio-Southern Oscillation （ENSO） is investigated. This is done through composite analysis of sea surface height （SSH） observed by satellite altimeter during October 1992-July 2009, and correspondingly derived sea surface geostrophic currents. During E1 Nifio/La Nifia years, the SSH in the tropical North Pacific Ocean falls/rises, with maximum changes in the region 0-15~N, 130~E-160~E. The decrease/increase in SSH induces a cyclonic/anticyclonic anomaly in the western tropical gyre. The cyclonic/anticyclonic anomaly in the gyre results in an increase/decrease of NEC transport, and a northward/southward shift of the NEC bifurcation latitude near the Philippine coast. The variations are mainly in response to anomalous wind forcing in the west-central tropical North Pacific Ocean, related to ENSO events.

Effect of suppressing dust by multi-direction whirling air curtain on fully mechanized mining face

A combined method of numerical simulation and field testing was adopted in this study in the interest of solving the problem of hard to control high concentrate dusts on a fully mechanized mining face. In addi- tion, the dust suppression effect of a multi-direction whirling air curtain was studied in this paper. Under the influence of the wall attachment effect, the compressed air which blows out from the two-phase or three-phase radial outlets on the generator of the air curtain can form a multi-direction whirling air curtain, which can cover the whole roadway section of a fully mechanized mining face. The traditional method of controlling dust is a forcing system with exhaust overlap which has the major disadvantage of lacking a jet effect and consequently results in poor dust control. It is difficult to form the air flow field within the range of Lp ≤ 5√S. However, due to the effect of this novel system, the radial airflow can be turned into axial airflow allowing fresh air to flow through the length of the heading. The air flow field which is good at controlling dust diffusion can be formed 12.8 m from the heading face. Furthermore, the field measurement results show that before the application of a multi-direction whirling air curtain, the dust concentration is 348.6 mg/m^3 and 271.4 mg/m^3 respectively at the roadway cross-section measurement points which are 5 m and 10 m from the heading face. However, after the application of the multi-direction whirling air curtain, the dust concentration is only 61.2 mg/m3 and 14.8 mg/m^3, respectively. Therefore, the dust control effect of a multi-direction whirling air curtain is obvious.

Impacts of Indonesian Throughflow on seasonal circulation in the equatorial Indian Ocean

Impacts of the Indonesian Throughflow(ITF) on seasonal circulation in the equatorial eastern Indian Ocean are investigated using the ocean-only model LICOM by opening and closing ITF passages. LICOM had daily forcing from NCEP reanalysis data during 2000–2011. It can reproduce vertical profiles of mean density and buoyancy frequency of World Ocean Atlas 2013 data. The model also simulates well annual oscillation in the central Indian Ocean and semiannual oscillation in the eastern Indian Ocean of sea level anomalies(SLA) using satellite altimeter data, as well as the semiannual oscillation of surface zonal equatorial currents of Ocean Surface Current Analyses Real Time current data in the equatorial Indian Ocean. The wave decomposition method is used to analyze the propagation and reflection of equatorial long waves based on LICOM output. Wave analysis suggests that ITF blockage mainly influences waves generated from the Indian Ocean but not the Pacific Ocean, and eastern boundary reflections play an important role in semiannual oscillations of SLA and zonal current dif ferences in the equatorial Indian Ocean associated with ITF. Reconstructed ITF-caused SLA using wave decomposition coefficient dif ferences between closed and open ITF-passage experiments suggest both Kelvin and Rossby waves from the first baroclinic mode have comparable contributions to the semiannual oscillations of SLA diff erence. However, reconstructed ITFcaused surface zonal currents at the equator suggest that the first meridional-mode Rossby wave has much greater contribution than the first baroclinic mode Kelvin wave. Both reconstructed sea level and zonal currents demonstrate that the first baroclinic mode has a greater contribution than other baroclinic modes.