草地生态农业与产品革新是西北地区农业的出路

针对西北地区农业越来越依赖化肥、农药来提高产量以及污染问题日趋严重的现状 ,提出将发展草地生态农业与革新产品作为该地区农业可持续发展的出路。建议先主抓多途径开辟有机肥源 ,大田作物资源化增值 ,快速解决奶牛牛源与增加系统生物多样性 4项 ,可改善生态环境 ,使农民增收 ,将农业生态系统导入良性循环     

冷轧薄板摩擦热及温升模型研究

冷轧时轧件塑性变形热和摩擦热是导致轧件温度升高的两个主要原因。采用包含滑动摩擦和粘着摩擦在内的预位移 滑动摩擦模型较准确地计算了轧制区摩擦热 ,并综合考虑轧件塑性变形热 ,推导了冷轧薄板温升计算公式。     

Formation of secondary inorganic aerosols by power plant emissions exhausted through cooling towers in Saxony

Background, aim, and scope  The fraction of ambient PM₁₀ that is due to the formation of secondary inorganic particulate sulfate and nitrate from the emissions of two large, brown-coal-fired power stations in Saxony (East Germany) is examined. The power stations are equipped with natural-draft cooling towers. The flue gases are directly piped into the cooling towers, thereby receiving an additionally intensified uplift. The exhausted gas-steam mixture contains the gases CO, CO₂, NO, NO₂, and SO₂, the directly emitted primary particles, and additionally, an excess of ‘free’ sulfate ions in water solution, which, after the desulfurization steps, remain non-neutralized by cations. The precursor gases NO₂ and SO₂ are capable of forming nitric and sulfuric acid by several pathways. The acids can be neutralized by ammonia and generate secondary particulate matter by heterogeneous condensation on preexisting particles. Materials and methods  The simulations are performed by a nested and multi-scale application of the online-coupled model system LM-MUSCAT. The Local Model (LM; recently renamed as COSMO) of the German Weather Service performs the meteorological processes, while the Multi-scale Atmospheric Transport Model (MUSCAT) includes the transport, the gas phase chemistry, as well as the aerosol chemistry (thermodynamic ammonium–sulfate–nitrate–water system). The highest horizontal resolution in the inner region of Saxony is 0.7 km. One summer and one winter episode, each realizing 5 weeks of the year 2002, are simulated twice, with the cooling tower emissions switched on and off, respectively. This procedure serves to identify the direct and indirect influences of the single plumes on the formation and distribution of the secondary inorganic aerosols. Results and conclusions  Surface traces of the individual tower plumes can be located and distinguished, especially in the well-mixed boundary layer in daytime. At night, the plumes are decoupled from the surface. In no case does the resulting contribution of the cooling tower emissions to PM₁₀ significantly exceed 15 μgm⁻³ at the surface. These extreme values are obtained in narrow plumes on intensive summer conditions, whereas different situations with lower turbulence (night, winter) remain below this value. About 90% of the PM₁₀ concentrations in the plumes are secondarily formed sulfate, mainly ammonium sulfate, and about 10% originate from the primarily emitted particles. Under the assumptions made, ammonium nitrate plays a rather marginal role. Recommendations and perspectives  The analyzed results depend on the specific emission data of power plants with flue gas emissions piped through the cooling towers. The emitted fraction of ‘free’ sulfate ions remaining in excess after the desulfurization steps plays an important role at the formation of secondary aerosols and therefore has to be measured carefully.     

Growth, photosynthesis and antioxidant responses of two microalgal species, Chlorella vulgaris and Selenastrum capricornutum, to nonylphenol stress

The effect of nonylphenol (NP) on growth, photochemistry and biochemistry of two green microalgae, Chlorella vulgaris and Selenanstrum capricornutum, and their ability to degrade NP were compared. The 96 h EC₅₀ of C. vulgaris and S. capricornutum were greater than 4.0 and 1.0 mg L⁻¹ NP, respectively, suggesting that the former species was more tolerant to NP. Both microalgae acclimated to NP stress through down-regulating their photosynthetic activities, including antenna size (chlorophyll a content), maximal photochemistry (Fv/Fm) and the light absorbed by PSII (ABS/CS₀), but the dissipation of energy from reaction centres (DI₀/RC) increased with the increase of NP concentrations. In C. vulgaris, the changes of these parameters were more significant than in S. capricornutum and recovered completely after a 96 h exposure. The antioxidant responses, such as GSH content, CAT and POD activities in C. vulgaris increased with the increase of NP concentrations after a 24 h exposure, but these changes disappeared with exposure time and recovered to the control levels after 96 h. In S. capricornutum, although GSH content, CAT and POD activities also increased when exposed to low- to moderate-NP concentrations, these values were significantly reduced at a high concentration (4 mg L⁻¹) even after a 96 h exposure, indicating its antioxidant responses were significantly delayed. It is clear that the more NP-tolerant species, C. vulgaris, acclimated better with a faster recovery of its photosynthetic activity from the NP-induced damage, and exhibited more efficient and rapid responses to NP-induced oxidative stress. C. vulgaris also had a higher NP degradation ability than S. capricornutum.     

基于人员心理-环境因素的火灾疏散速度修正方法研究

为探究人在火灾环境下的行为心理对疏散效率的影响，基于火灾下人员行为心理特征具有复杂、抽象、难以直接量化的特性，通过模糊逻辑方法，应用模糊集合、模糊规则和隶属度函数量化人的行为心理，研究其对疏散速度的影响；考虑火灾烟气和群体行为对疏散的影响，通过对高层建筑火灾状况下的烟气进行数值分析，并运用公式法得出人员的疏散速度折减值；以某高层商业建筑火灾疏散为例，将修正后人员的疏散速度和疏散路径引入疏散分析并与未修正的结果进行比较。结果表明:未修正的商业建筑疏散时间为470 s，修正后的疏散时间为670 s，修正后的疏散时间更长，人员危险性更大。     

高层建筑电气火灾隐患因子定量分析方法研究

为了对高层建筑电气火灾隐患排查进行定量化分析，采用解释结构模型构建高层建筑电气火灾隐患因子的复杂逻辑模型；在利用德尔菲法确定隐患因子初始概率的基础上，经过交叉影响分析法求解交叉影响概率矩阵；引入马尔科夫链修正各隐患因子交叉影响后的概率，得到火灾隐患因子的稳态概率矩阵。研究结果表明:各隐患因子的马尔科夫链校正概率比德尔菲法测定的初始概率更加准确，该计算排序结果可明确高层电气火灾隐患排查和管控的重点。     

The impact of coastal flooding on conservation areas: A study of the Clyde Estuary, Scotland

This study examines the impact of flooding on land of high conservation value located along part of the southern shoreline of the River Clyde Estuary in western Scotland. This paper hypothesizes that, over the next 50 years, the frequency and extent of coastal flooding will increase due to the gradual effect of global warming and the consequent rise in sea-level and increase in storminess. It is argued that because of the great cost of constructing new flood defence systems it will not be possible to protect all land areas to an equal extent from flooding. A means of ranking different land use will be necessary so that society can make a rational judgement concerning which sections of coastline will be worth protecting. This study provides a methodology that combines an objective ranking of conservation areas using non-economic indicators with a GIS model of flood potential, and permits accurate forecasts of flood losses to conservation areas of different ecological value. The conservation case study used in this paper proposes the use of an ecological weighting value based on five ecological variables each of 10 categories. Tables and maps identify the sites that have been highlighted as consisting of the most ‘valuable’ conservation sites. The methodology makes extensive use of geographical information systems (GIS) to model the predicted areas of flooding and to calculate conservation weighting values of the land areas.     

排烟冷却塔烟气抬升高度的计算分析

华北地区某电厂排烟冷却塔烟气抬升高度的光学照相法实测结果显示，选用S／P模式计算出排烟冷却塔烟气括升高度是合理的。在环境风速小、空气潮湿条件下，采用排烟冷却塔排放方式有利于污染物稀释扩散；在环境风速大、空气干燥、逆温等不利气象条件时，采用排烟冷却塔排放方式，烟气抬升高度较低。     

泄爆导管对球形容器内气体爆炸泄放过程影响的试验

设计了球形容器内气体爆炸通过导管泄爆的试验系统,选用体积分数为10%(特殊说明除外)的甲烷和空气预混气体开展试验,研究了泄爆导管长度、容器容积、点火位置、气体体积分数、破膜压力等因素的影响。结果表明:泄爆导管越长,容器内的正压力峰值和负压力峰值越大;密闭爆炸时,球形容器的容积对爆炸压力峰值几乎无影响;不同容积球形容器内气体爆炸通过相同导管泄爆时(导管长度均为6 m,直径均为0.06 m),容积大的容器内的压力锋值为小容器压力值的3.3倍,且大容器内的压力上升速率也明显高于密闭爆炸的情况;有泄爆导管存在时,尾部点火容器内的压力峰值高于中心点火;泄爆导管的存在使得容器内的压力峰值高于直接泄爆时的压力峰值;无论有、无泄爆导管,容器内的压力峰值均随破膜压力增加而增加,但差值越来越小,说明导管的存在对容器爆炸泄爆过程的影响趋向缓和,但导管的存在总是阻碍了泄爆过程,增加了爆炸的严重程度,因此,在泄爆设计时要充分考虑导管的影响,适当提高容器自身的耐压强度。