埋地原油管道油品泄漏扩散三维数值模拟

为了评估埋地原油管道泄漏的危害范围,以原油管道泄漏事故为研究对象,采用计算流体力学等理论知识,建立了埋地输油管道三维泄漏扩散过程的物理模型和数学模型,确定了泄漏前稳态的初始条件和泄漏后非稳态的边界条件;利用FLUENT软件进行了数值模拟,计算出了不同时刻油品在土壤中的扩散范围。计算结果表明,管道泄漏后原油扩散范围与泄漏时间保持一定变化规律,在无法检测扩散深度的情况下可根据扩散宽度进行粗略估算,大体确定事故泄漏扩散范围,可以为事故处置提供参考,提高事故的应急控制能力。     

黄土湿陷过程下埋地油气管道力学行为有限元模拟

针对黄土遇水后湿陷产生陷穴并引起埋地管道悬空这一过程中管道的力学行为,以基于弹塑性地基的黄土湿陷区悬空管道力学模型为基础,从湿陷原因和机理出发,建立三维有限元实体模型,模拟了土体湿陷过程和沉降变形,模拟计算结果与理论值和实测值进行了比对验证;进一步的计算和回归分析得到了管道最大位移、最大von Mises应力与地表土体湿陷沉降量的变化规律,同时也得到了最终湿陷情况下管道的von Mises应力分布和湿陷区范围的影响。结果表明:土体湿陷沉降是管道和土体共同作用的结果,湿陷前期管道与土体一起运动,位移和应力增加较快,而管道下方土体脱离管道产生陷穴后则增长较慢;管道最大位移和土体湿陷沉降量间呈对数函数关系,而管道最大von Mises应力和土体湿陷量呈指数函数关系; 湿陷区管段向下弯曲变形会在3个位置形成应力集中区,湿陷区范围增大会引起管道应力和变形的明显增加,且3个区域的最值分布有所不同。     

Species Composition and Ecological Characteristic of Algae from the Cooling Reservoir of the Beloyarsk Nuclear Power Plant

The results of long-term studies on phytoplankton in the cooling reservoir of the Beloyarsk Nuclear Power Plant (the Middle Urals) are reviewed. Altogether, 199 taxa of the species and subspecies rank have been recorded, including 144 taxa described in this water body for the first time. The algoflora of the reservoir consists mainly of widespread and eurybiontic freshwater species.     

Rangeland utilisation assessment and modelling for grazing and fire management

To support grazing and fire management of communal semi-arid to sub-humid African rangelands, the assessment of grazing capacity is illustrated for cattle. The forage dry matter intake (DMI) was divided into four components: 1) the mature standing crop, 2) the green part of the standing crop, 3) the regrowth after range fires, and 4) browse. The relationship between the potential DMI and the crude protein (CP) concentration of the forage was modelled. The DMI ranged from 5 to 50% for forage with low to high CP concentrations, respectively. The DMI of browse was fixed at 0 and 10% of the DMI of unburnt vegetation for plain and woodland systems, respectively. The potential DMI of the four forage components combined, based on data of the early- to mid-dry season, was matched with livestock requirements to calculate grazing capacities. Possible combinations of and changes in the forage components, representing grazing capacities for different seasons of the year, were calculated and visualised. Lastly, it was demonstrated how to assess the proportion of the rangeland that should be burnt to make optimal use of the low quality forage available in abundance and the small amount of high quality regrowth.     

A novel radiant floor system: Detailed characterization and comparison with traditional radiant systems

ABSTRACT

Radiant floor systems have the potential to reduce energy consumption and the carbon footprint of buildings. This study analyzed a novel radiant panel configuration comprising a metal plate with small spikes that can be pressed into cement board or wood. The behavior of this configuration was simulated for different materials for the metal plate, spike dimensions, and varying spacing between spikes. An annual energy simulation model compared the radiant panel configuration with the traditional concrete-based system. Simulations were run under heating dominant, cooling dominant, and neutral conditions; significant cost savings and greenhouse gas emission reduction were seen across all scenarios.     

直升机蒸气循环制冷系统技术现状与展望

笔者主要从舱内环境控制方面 ,分析了高温对直升机飞行安全的影响 ,指出了直升机安装制冷系统的必要性 ,同时对国外现役直升机采用的两种制冷系统即蒸气循环制冷系统与空气循环制冷系统进行了性能对比。在此基础上 ,提出我国发展直升机制冷系统的主推方案是蒸气循环制冷系统 ,并对我国进行直升机蒸气循环制冷系统研究的技术关键和发展方向给予展望 ,为我国开展此领域的科学研究和技术创新提供一定的技术储备。     

花期低温对寒地水稻颖花结实的影响

利用人工气候室在水稻开花期进行13℃,17℃,21℃和25℃等不同温度的处理,结果表明低温可降低水稻颖花的结实率,且不同品种水稻对低温的反应不同.低温的强度和持续时间与水稻颖花结实率呈明显的负相关关系,13℃气温持续12d,其颖花的结实率可降到30%以下.低温处理前、后开的颖花,其结实率随低温强度的加大和持续时间的延长而降低.     

WATER YIELD IMPROVEMENT POTENTIAL BY VEGETATION MANAGEMENT ON WESTERN RANGELANDS1

Increasing water for onsite and offsite uses can be a viable objective for management of certain western rangelands. One approach utilizes water harvesting techniques to increase surface runoff by preventing or slowing infiltration of rain. An attractive alternative, where applicable, is to replace vegetation that uses much water with plants that use less so that more water percolates through the soil to streams and ground water. Most sites are too dry to increase water yield in this way; probably less than 1 percent of the western rangelands can be managed for this purpose. However, where annual precipitation exceeds about 450 mm (18 inches) and deep-rooted shrubs can be replaced by shallow-rooted grasses, there is potential to increase streamflows and to improve forage for livestock. Little or no increase can be expected by eradication of low-density brush and pinyon-juniper woodlands. Potentials for improving water yield are reviewed and summarized by vegetation types.     

不同汽车发动机冷却系统的节能减排效益及安全性分析

由于传统发动机冷却系统的被动性,常使发动机能耗及污染物排放量较大,为此介绍了多种先进冷却系统的结构和特点,如精确冷却系统、分流式冷却系统、优质冷媒的使用等,并分析了它们的节能减排效益,以为汽车行业加快实现节能减排提供参考。     

东海西湖凹陷区溢油行为数值模拟

研究东中国海中日共同开发区附近海域溢油污染的问题,在模拟水动力场的基础上模拟了海上溢油漂移扩散情况。在表层流场和风场的作用下漂移,而油膜的扩展则通过油粒子的随机走动来实现。本文以东海西湖凹陷原油为溢油油种,通过模拟分析不同季节和不同风况下的溢油事故,对溢油油膜的扫海范围进行了分析。