台阶式消能在某水电站泄水槽设计中的应用

对于长距离泄水槽,坡度缓水头高,常规设计消能工规模大,为此在底板上设置台阶,增加糙率,以减小消能工的规模。应用近似糙率法、CHANSON经验公式法对某长距离台阶式泄水槽进行了水力计算。计算结果符合经验规律,经工程实际运行验证2种计算方法均可应用于工程设计;台阶式泄水槽减速掺气消能效果显著,减少了工程投资。     

托巴水电站古松料场开采运输方案研究

溜井运输方案在国内外的冶金、煤炭、建材等行业已被广泛采用,并在设计、运行方面取得了较为成功的经验,在国内龙滩、锦屏等水电工程的料场开采运输中也得到了成功的运用。托巴水电工程古松料场地形陡峻,开采边坡高约300m,开采运输道路修建困难,且距坝区较近,对坝区施工干扰较大。通过对"公路运输方案、溜井+公路运输方案、溜井+胶带机运输方案"3个开采运输方案进行比较,初步推荐采用"溜井+公路运输方案",以有效解决料场开采运输存在的问题。     

无中隔墩卧底式窄缝差动挑坎的设计研究

针对目前在多孔河岸式溢洪道上采用窄缝挑坎消能工，都是沿闸墩用长墩隔开，至出口段将墩体升高加厚、急剧收缩成窄缝的结构形式。全程隔墩混凝土用量大，加上强大侧向水压力荷载等影响到工程投资、结构安全与泄洪运行管理问题。该设计提出省去泄槽中部的长隔墩，只在溢洪道出口连续挑坎下部加入“卧底式窄缝”，借以实现继续应用收缩式消能工。经模型试验表明：通过“分段连续坎”与“窄缝”的差动作用，出射水舌抛射呈十、廿、卅字形，加大入水面积和碰撞机率，消能效果良好，并方便人为控制水舌落点。在水电工程中有扩大应用潜力。     

真空灭弧室的一次封排工艺

一次封排工艺是生产真空灭弧室的先进工艺，排气，封口同时进行一次完成。本文介绍了一次封排工艺的特点，及一次封排工艺的几点关键问题。     

Short Communication: Scoring of Digital Dermatitis During Milking as an Alternative to Scoring in a Hoof Trimming Chute

Digital dermatitis is a serious problem in dairy production in many countries. In many settings, it is important to evaluate the digital dermatitis status of individual cows or an entire dairy herd. Such an evaluation has traditionally been done in a hoof trimming chute. An evaluation in the milking parlor can take place without disturbing the cows to a large extent, it can be done using less labor compared with an evaluation in a hoof trimming chute, and is cheaper than using a chute. The objective was to evaluate the sensitivity and specificity of a rapid screening method for digital dermatitis in the milking parlor, without using any specialized tools and taking approximately 15 s/cow. All lactating cows in 3 commercial Danish dairy herds were included. Cows were first scored for the presence of digital dermatitis during milking and the next day all cows were scored during hoof trimming. A 6-point nominal scoring system based on a visual inspection of the digital dermatitis lesions was used. For the analysis, the scores were dichotomized (digital dermatitis positive or digital dermatitis negative). Additionally, lesions were classified as small (diameter ≤ 2 cm) or large (diameter >2 cm). Sensitivity and specificity were calculated using observations from the hoof trimming chute as the “gold standard” and observations during milking as the diagnostic test. Relatively large variation was found between herds with an overall sensitivity of 0.65 (95% confidence interval: 0.59 to 0.72) and a specificity of 0.84 (0.81 to 0.87). The sensitivity increased to 0.69 (0.62 to 0.76), when only large lesions were assessed. The method has several advantages compared with evaluation in a chute and may be a useful tool in the daily hoof health management in dairy herds.     

大花水水电站碾压混凝土拱坝快速施工技术

大花水水电站拦河大坝为碾压混凝土双曲拱坝,最大坝高134.50 m。采用快速施工技术,创造了国内碾压混凝土连续浇筑上升33.5 m的记录。重点介绍了高速胶带机水平运输技术、缓降溜管垂直运输技术以及碾压混凝土仓面工艺。     

峨口铁矿矿石主溜井加强支护技术的探讨

为保证峨口铁矿矿石主溜井的安全运行,需要对其进行加固支护。经现场调查、充分研究和工程类比等技术手段,确定了溜井支护施工工艺和参数。方案实施后效果良好,对类似工程有借鉴和指导作用。     

吉尔吉斯斯坦某锡矿中锡石回收试验研究

根据吉尔吉斯斯坦某锡矿的原矿性质,进行了该矿石中锡石回收的选矿试验研究。采用"螺旋溜槽预先抛尾—螺旋溜槽粗精矿分粒级摇床重选—重选粗精矿脱硫脱砷"工艺流程,可实现该锡矿中锡石的有效回收,获得锡精矿锡品位47.61%,锡回收率75.71%的选别指标。     

斜梁式卸煤沟的破坏机理及简化模型

采用1/10缩尺比例的钢筋混凝土模型,对卸煤沟在运行荷载和结构从开裂到破坏的全过程进行了试验.结果表明主梁的斜向布置对侧壁和底板影响较小,斜梁具有弯扭耦合的特性.在此基础上提出用带抗扭约束的简支斜梁和平面刚架分别模拟斜梁和沟槽的简化设计模型,与规范正交卸煤沟的设计方法相统一且计算结果偏于安全.     

特长隧道投料系统优化研究

针对象山隧道2号斜井混凝土运输难题,介绍了采用混凝土竖直投料孔与斜井内混凝土溜槽下放2号斜井施工混凝土的具体方法和步骤,从而解决2号斜井长距离衬砌滞后而潜在安全风险的问题,为后续施工积累了经验。