生物多样性维护功能评估及其空间尺度效应分析——以陕西省为例

生物多样性维护功能评估是生态系统综合评估的重要内容。基于物种丰富度的海拔梯度格局规律来修正生物多样性维护服务能力指数模型,并探讨该模型在省级、市级和生物多样性优先区三种不同尺度水平的评估响应。结果显示：（1）三种尺度识别的生物多样性极重要区面积和空间分布差异较大,省级尺度评估的极重要区集中于秦巴山地,市级尺度评估时极重要区分布广泛且布局分散,优先区尺度评估时极重要区与自然保护区重叠面积最大。（2）三种尺度评估识别的精准度由大到小依次为：优先区尺度（19.5%）>省级尺度（11.7%）>市级尺度（11.2%）,优先区尺度评估识别的精准度明显高于行政区尺度的评估。（3）优先区尺度评估识别的极重要区面积为28032.3 km²,占陕西省国土面积的13.7%;极重要区内土地利用结构和物种重要性综合评估结果优于行政区尺度的评估结果。     

偏转角影响磁纤维捕集Fe基细颗粒的数值模拟

为了研究磁性纤维对钢铁行业细颗粒物的控制效果,基于计算流体力学-离散相模型（CFD-DPM）对高梯度磁场中含尘气流方向与背景磁场方向夹角（偏转角）分别为0°、15°、30°、45°、60°、75°、90°时磁性单纤维捕集Fe基细颗粒进行数值模拟.分别研究高梯度磁场作用下颗粒粒径、入口风速、磁场强度对颗粒运动轨迹和捕集效率的影响.结果表明：高梯度磁场中偏转角影响磁性纤维捕集区域的位置,当角度为0°时,在纤维正对含尘气流方向区域形成颗粒捕集区,背风侧形成较大空腔;当角度为90°时,在沿气流方向纤维两侧形成面积相等的捕集区域.偏转角对小颗粒捕集效率的影响较小,当角度为0°时,对于0.5μm的颗粒捕集效率为4.1%,当角度为90°时捕集效率为3.9%.随着粒径的增大,捕集效率的增长速率先减小后增大,对于不同粒径的颗粒,当角度为0°时捕集效率最高.当风速在0.02~0.04m/s范围时,随着角度从0°增加到90°,捕集效率先降低,在45°附近达到最小值,然后升高.磁场强度的增加有利于提高捕集效率,但不同角度时的增长速率有所不同.当偏转角为0°和60°时,背景磁场强度为0.1~0.3T范围时增长速率明显大于0.3~0.9T范围内,而当偏转角为30°和90°时,背景磁场强度为0.1~0.5T范围时增长速率高于0.5~0.9T时的增长速率.     

我国区域产业梯度转移中的环境风险及对策

近年来,我国SO₂和COD 2种主要污染物的排放强度逐年下降.以1998年主要污染物排放总量为基数,分析了1998─2007年我国东、中、西部地区的主要污染物排放总量,结果表明,相对于东部地区,中、西部地区污染没有得到更好的控制. 采用古诺模型研究该现象可知,中、西部地区有些地方通过对国家环境政策的“非完全执行”来吸引产业转移,使污染企业转移成为我国区域产业梯度转移的伴生现象. 因此,有必要有序推进产业梯度转移,强化产业梯度转移中的环境正效应,通过严格执行国家环境政策来防范环境风险,从而实现整体环境质量的改善.      

雨强和坡度对裸地径流颗粒物及磷素流失的影响

采用人工模拟降雨的方法,研究了不同雨强（0~100mm/h）和坡度（0°~10°）条件下,北方砂壤土裸地降雨径流中颗粒物（SS）、总磷（TP）、颗粒态磷（PP）的流失量及径流污染物之间的相关关系,并分析了雨强和坡度对污染物流失量的影响.研究结果表明,雨强和坡度越大,SS和TP流失量越大;径流中SS与TP、TP与PP的单位面积流失量呈显著线性相关关系（R²>0.946）;在实验条件范围内,雨强对颗粒物及磷素流失量的影响比坡度更显著;径流中颗粒物及磷素单位面积流失量与雨强、坡度及场降雨径流总量之间均有明显的线性关系,相关系数大于0.911,由于0°裸地和有坡度裸地的下渗及产流情况差异较大,在模拟雨强和坡度对颗粒物及磷素流失量影响时需分别考虑.结果可为我国北方砂壤土裸地径流中颗粒物及磷素单位面积流失量的估算提供计算方法和科学依据.     

Modelling of a downdraft gasifier fed by agricultural residues

A non-stoichiometric model for a downdraft gasifier was developed in order to simulate the overall gasification process. Mass and energy balances of the gasifier were calculated and the composition of produced syngas was predicted. The capacity of the modeled gasifier was assumed to be 0.5 MW, with an Equivalence Ratio (EQ) of 0.45. The model incorporates the chemical reactions and species involved, while it starts by selecting all species containing C, H, and O, or any other dominant elements. Olive wood, miscanthus and cardoon were tested in the formulated model for a temperature range of 800-1200 °C, in order to examine the syngas composition and the moisture impact on the supplied fuel. Model results were then used in order to design an olive wood gasification reactor.     

Gradient modeling: A new approach to fire modeling and wilderness resource management

Managers of wilderness resources must maintain, preserve, and sometimes restore pristine ecosystems while providing for public use and enjoyment of these areas. These managers require a resource information system that can store, retrieve and integrate basic data, synthesize components to solve particular problems, and provide simulations and predictions of natural processes and management actions. Traditional information systems based on land classification and type-mapping do not provide these capabilities.Gradient modeling, a new approach to resource management and forest fire simulation, has been developed to meet these needs in Glacier National Park. The method links four major components: (1) a terrestrial site inventory coded from aerial photographs that offers 10-m resolution; (2) gradient models of vegetation and fuel that derive quantitative stand compositional data from the parameters stored in the coded inventory; (3) a fuel moisture and microclimate model that extrapolates basestation weather data to remote sites using the parameters stored in the inventory; and (4) fire behavior and fire ecology models that integrate the data from the inventory and models to calculate real-time fire behavior and ecological succession following a fire.     

严寒地区某斜拉桥冬季混凝土箱梁温度梯度试验研究

为了揭示严寒地区冬季温度梯度对混凝土箱梁的影响,笔者对绥芬河斜拉桥箱梁的初期运营阶段进行了全天候的温度测试。从理论和试验两个方面,验证并揭示温度是如何传递并影响箱形梁的,进而明确热传导、热对流、热辐射分别对箱梁的影响程度。为严寒地区混凝土斜拉桥设计时温度荷载的确定提供参考,也为以后箱梁温度梯度监测时间的确定建立科学依据。试验发现负温度梯度明显存在、实测温度梯度较小,满足中美两国规范的要求、冬季的温度梯度值远远小于夏季。建议今后对严寒地区斜拉桥的设计,主要应考虑辐射热大的夏天温度应力对箱梁混凝土的影响。     

水位变动对库区边坡稳定性的影响机理研究

利用数值模拟手段,对选定的库区边坡进行稳定性分析,得到了不同水位变动情况下的边坡稳定情况。认为水位的变动类型和变动率会对边坡的稳定造成影响,但影响效果不一样。从数学解析角度出发,推导出了库区水位上升与下降时,水力梯度与水流渗透方向、边坡倾斜角度三者之间较为理想化的关系形式。在此基础上,对边坡体内不同部位的水流情况以及所带来的影响进行了分析。进一步的,还从有效应力的角度,对水位变动影响边坡稳定性的机理进行了研究,且由不同方法所得的结论能够较好的相互印证。     

Bacterial community composition and abundance in leachate of semi-aerobic and anaerobic landfills

Different municipal solid waste landfill methods and landfill ages had crucial impacts on bacterial abundance and composition in leachate.     

Experimental investigation of the pressure gradient of a new spiral mesh foam generator

Foam is used as part of an effective dust suppression method in underground coal mines, but conventional foaming devices severely restrict its popularization and application due to the high cost of foam preparation, poor applicability and high pressure loss. Therefore, a new spiral mesh foam generator is designed, and its performance is investigated and evaluated experimentally. The results show that the pressure gradient of the spiral mesh foam generator increases with the increase of foam concentration in water. There is a large pressure gradient gap between the top and bottom at both ends of the foam generator. However, the gap disappears and uniform foam is generated in the middle section of the foam generator. When the pressure gradient is higher than minimum pressure gradient, the foam production quantity will increase sharply. Based on the length of spiral mesh and operating conditions determined, the new foam generator is applied to produce foam for dust suppression in the heading face of coal mines. A good foaming effect, less pressure loss and high dust suppression efficiency suggest that the new foam generator will greatly promote the large-scale application of foam technology used to suppress dust in underground coal mines.