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621.
对大型水电站施工期污水截排工程进行设计能够降低污水排放量,对环境保护具有重要意义,针对当前大型水电站施工期污水截排工程存在的截排效果与工程投入成本之间矛盾的问题,提出一种基于污水截排流量的大型水电站施工期污水截排工程设计方法,首先对大型水电站施工期污水的来源进行分析,确定污水中主要污染物,然后对大型水电站施工期污水截排工程的设计任务进行分析.实现结果表明,所提方法设计的污水截排工程能够实现截排效果与工程投入成本之间的有机统一,在降低工程投入的同时保证截排效果. 相似文献
622.
Anna Marszałek Grażyna Grabowska Krzysztof Łężak The Secret Study Group 《International journal of occupational safety and ergonomics》2019,25(2):268-277
Research into newly developed ballistic vests to be worn by police officers under clothing was carried out with air temperature conditions of +20 °C. A ballistic vest should incorporate protective features, comfort and ergonomics. The thermal strain on users who wore the vests was evaluated as an average and individually, after they had been conditioned in high (+50 °C), low (?40 °C) or neutral (+20 °C) air temperatures, while performing various occupational activities. Research involved six police officers aged 36–42 years, who wore civilian clothing used in moderate environmental conditions. During the tests, physiological parameters (internal temperature, local skin temperatures and amount of sweat secreted) were determined. The ease of doing exercises while wearing the vests, vest service and level of discomfort in use were assessed. Research showed that the vests tested, both as an average and individually, meet the requirements of Standard No. PN-V-87000:2011 (clause 4.5). 相似文献
623.
为研究大型机加车间噪声现状和特点,选取某大型机加车间数控机床开展现场实测,并对噪声测量结果进行分析。结果显示:数控机床产生的噪声是非稳态噪声;数控机床产生的噪声在车间传播,声场分布不均匀;加工某转向工件频率在500~5 300 Hz,峰值频率分别为500,800,2 000,5 000 Hz;对机加数控机床操作岗位工作人员的8 h噪声暴露量进行测量,测量值为89.2 dB(A)。研究结果表明:评价大型机加车间噪声,测量重点应选在机床操作岗位和人行通道;应重点关注被测机床周围20 m内的噪声值;机加工作场所测量时间段的选择取决于作业持续时间。 相似文献
624.
为了探究大落差管道充水投产过程中存在的不满流及低点超压问题,以中缅原油管道怒江跨越段为例(其最大高差达1 480 m),基于OLGA多相流瞬态模拟方法,对大落差原油管道充水过程进行仿真研究,重点分析到达管道不同低点位置的最大速度、压力及相应持液率,得到不同输量条件下不同低点位置的水流速度、压力及持液率随时间变化规律。结果表明:当输量为900~2 000 m3/h时该管道中存在的段塞流概率降低57%,同时减少了管压波动以及对管道和设备的破坏,提高了管道输送效率。 相似文献
625.
为解决土城煤矿14运输上山软岩巷道变形量大、锚杆索失效严重等技术难题,通过现场调研、室内试验、理论分析、数值模拟及工业性试验等方法,揭示了围岩变形特征以及巷道失稳破坏机理,提出了“三壳”围岩控制理论。基于以上研究,设计了“锚杆锚索+灌浆+钢管混凝土支架”的复合支护方案,建立了基于“三壳”围岩控制理论的“三壳”支护结构体力学模型,计算出设计方案的极限承载能力为2.54 MPa,随后采用 FLAC3D数值模拟软件对设计方案进行模拟分析,验证了方案合理性。最后,该复合支护得到成功运用,现场监测结果表明:巷道顶底板以及两帮变形量均低于100 mm,巷道未发生明显变形,支护效果良好。 相似文献
626.
安太堡露天矿排土场表层岩土的径流特征与复垦种植研究 总被引:1,自引:0,他引:1
采用针孔式小型人工降雨机,分别模拟山西塞北高原90~60min,60~45min,45~30min,30~15min各时段降水量极大值,探讨大型露天矿排土场各种排土工艺下地表岩土的径流特征,以指导排土工艺和复垦种植。 相似文献
627.
S. Mazzoli 《Geologische Rundschau》1995,84(4):781-793
Analysis of strain in Jurassic argillites forming part of the folded and thrusted sedimentary succession of the Lagonegro basin (southern Italian Apennines) has been carried out using ellipsoid-shaped 'reduction' spots as strain markers. Most of the determined finite strain ellipsoids are of oblate type and show a peculiar distribution of the maximum extension direction ( X), with maxima either subparallel or subperpendicular to the local fold axes. Using the strain matrix method, two different deformation histories have been considered to assist the interpretation of the observed finite strain pattern. A first deformation history involved vertical compaction followed by horizontal shortening (occurring by a combination of true tectonic strain and volume loss), whereby all strain is coaxial and there is no change in the intermediate axis of the strain ellipsoid. By this type of deformation sequence, which produces a deformation path where total strain moves from the oblate to the prolate strain field and back to the oblate field, prolate strain ellipsoids can be generated and may be recorded where tectonic deformation has not been large enough to reverse pre-tectonic compaction. This type of deformation history may be of local importance within the study area (i.e. it may characterize some fold hinge regions) and, more generally, is probably of limited occurrence in deformed pelitic rocks. A second deformation sequence considered the superposition of pre-tectonic compaction and tectonic strain consisting of initial layer-parallel shortening followed by layer-parallel shear (related to flexural folding). Also in this instance, volume change during tectonic deformation and tectonic plane strain have been assumed. For geologically reasonable amounts of volume loss due to compaction and of initial layer-parallel shortening, this type of deformation history is capable of producing a deformation path entirely lying within the oblate strain field, but still characterized by a changeover, during deformation, of the maximum extension axis ( X) from a position parallel to the fold axis to one perpendicular to it. This type of deformation sequence may explain the main strain features observed in the study area, where most of the measured finite strain ellipsoids, determined from the limb regions of flexural folds, display an oblate shape, irrespective of the orientation of their maximum extension direction ( X) with respect to the local structural trends. More generally, this type of deformation history provides a mechanism to account for the predominance of oblate strains in deformed pelitic rocks. Key words Finite strain states · Compaction · Tectonic strain · Deformation gradient tensors · Deformation paths 相似文献
628.
629.
Ji Shulan Liu Zhipei Liu Zhipeng Ren Haiyan 《Frontiers of Environmental Science & Engineering in China》2007,1(3):325-328
A bacterial strain, ZY3, growing on sex steroid hormones as the sole source of carbon and energy was isolated from the sewage
treatment plant of a prophylactic steroids factory. ZY3 degrades the 3-methoxy-17β-hydroxy-1,3,5(10),8(9)-δ-4-estren (MHE).
This strain was preliminarily identified as Raoultella sp. ZY3 according to its morphology and its 16S rRNA gene sequence. During the experimental period (72 h), the optimum temperature,
pH and 3-MHE concentration for the degradation of hydride by the strain ZY3 were 35°C, 10 and 10 mg/L, respectively. The degradation
rate of the sex steroid hormones increased to 87% and 85% after the addition of maltose and peptone, respectively.
Translated from China Environmental Science, 2005, 25(5): 585–588 [译自: 中国环境科学] 相似文献
630.