循环流化床燃烧过程自适应双环选择控制系统

本文根据循环流化床燃烧过程的动态特性和现场运行经验 ,提出了 1种符合实际应用的自适应双环选择控制系统。该系统在床层温度不越限的情况下 ,以控制主蒸汽压力稳定为主要目标。当床层温度发生越限时 ,系统自动变换控制策略并调整床层温度恢复到正常 ,这种控制方式有效地减弱了主蒸汽压力与床层温度之间的耦合关系。该系统结构简单、实用 ,具有工程应用价值 ,现场运行收到较好的控制效果     

冷原子荧光法直接测定海水中痕量汞

用冷原子荧光直接测定海水中的痕量汞,目前在我国还未正式使用.国内外普遍使用的是无焰原子吸收或冷原子吸收法进行直接分析或富集浓缩后进行分析[1,2].但富集法步骤麻烦、装置复杂、容使样品污染,且样品用量大,要消耗大量的试剂和分析时间.本文叙述了利用国产YYG-77型冷原子荧光测汞仪[3,4,5],改进了还原器,使用封闭进样,使整个体系在测量时处于封闭状态,消除了由于空气进入而产生的荧光猝灭;同时对不同的进样方式作了比较实验.通过大量实验,选择了最佳实验条件和适当的反应的体积,取样量改为50毫升,使本方法的检测限由原仪器的0.05微克/升降低到0.002微克/升;精密度为2-5%.每个样品的测定时间只需40-60秒.本方法适于天然海水中痕量汞的测定,也便于海上操作.     

兰新高铁烟墩风区戈壁近地表风沙流跃移质垂直分布特性

跃移质作为风沙流的主体,其近地表垂直分布规律是风沙物理学的重要研究内容,对防沙工程具有重要的指导意义。受研究条件与观测仪器限制,戈壁特别是极端大风区近地表风沙流结构特性研究较为薄弱。利用多梯度风蚀传感器与阶梯式集沙仪对兰新高铁烟墩风区戈壁近地表风沙流跃移质的垂直分布特性进行了观测研究。结果表明：兰新高铁烟墩风区戈壁沙粒发生跃移运动的2 m高临界风速达12 m·s^-1;戈壁近地表风沙流具有明显的阵性特征,沙粒跃移发生的时间比例在50%以下,与平均风速成正相关关系,与风速脉动强度无显著相关关系;2 m高阵风7级风速下,戈壁跃移沙粒主要集中于地表50 cm范围内,近地表风沙流结构呈"象鼻效应",跃移质最大质量通量出现在地表2.5~5 cm高度处,沙粒最大跃移高度可达2 m,且沙粒跃移高度随2 m高风速的增加呈指数规律递增。因此,兰新高铁烟墩风区2 m高阻沙栅栏不足以完全阻截戈壁风沙流,是造成烟墩风区兰新高铁轨道积沙的重要原因之一。     

Modeling and verifying the impact of time delay on INS-aided GNSS PLLs

The timing error between global navigation satellite system (GNSS) and inertial navigation system (INS) processes limits the integration performance in GNSS/INS integrated systems. In a deeply coupled system, this timing error affects not only the integrated navigation solution, but also the GNSS signal tracking. We propose a time-domain model of INS-aided second-order phase-locked loops (PLLs) in consideration of the INS aiding delay, and analyze the effect of INS aiding delay on the tracking errors in details. In addition, an integrated hardware deeply coupled system platform was developed to verify the impact of time delay on INS-aided PLLs. Simulation and field vehicles testing results demonstrate that the tracking error of the INS-aided PLL caused by aiding delay increases with the lengthening of the delay time, the compression of the bandwidth, and the increase in the acceleration. Testing results verify the proposed model.     

Thaw-induced slope failures and stability analyses in permafrost regions of the Qinghai-Tibet Plateau,China

The distribution of permafrost-related slope failures along the Qinghai-Tibet Highway from Wuddaoliang to Fenghuoshan correlates with ice content, slope gradient, and ground temperature. Slope failures are of two types. (1) Retrogressive thaw slumps result from icy permafrost being exposed by either man-induced excavation or fluvial-thermal erosion and undercutting of basal slopes. (2) Active-layer-detachment failures are caused by thaw of icy permafrost at the active layer-permafrost interface. After initial failure, active-layer-detachment failures can lead to retrogressive thaw-slumping and localized surficial landslide. Common trigger mechanisms for failure include high summer air temperatures and heavy summer precipitation. A third possible trigger mechanism for slope failure is earthquake occurrence. A geotechnical slope stability analysis was undertaken for an active-layer-detachment failure that had progressed into a retrogressive thaw slump. A safety factor (F _s ) of 1.24 for the natural slope was determined using in situ tested strength parameters. However, the slope would lose stability when either the groundwater level over the permafrost table exceeded 1.42 m or seismic acceleration reached, or exceeded, 0.03?g.     

裂隙各向异性介质2.5维弹性波场数值模拟

研究地震波在各向异性介质中的传播规律是勘探地震学领域的一个重要内容。本文首先讨论了２．５维波动方程，其次，在２．５维空间，用有限元数值模拟方法模拟了裂隙各向异性介质波场，结果用波场切片做了显示。最后对模拟结果做了基本分析，这里讨论的模拟方法也适用于其它类型的得各向异性介。     

Progress of Tracing Fossil Fuel CO2 by Radiocarbon in Chinese Cities

The main cause of increase in atmospheric CO₂ concentration is the carbon emissions from fossil fuel combustions and so on. Cities are regarded as the hot spots of carbon emissions. On the basis of obtaining the levels and spatial-temporal variation characteristics of atmospheric fossil fuel CO₂ （CO_2ff）， we can provide scientific data for government policy-making and international negotiations on carbon reductions. In the recent ten years， some important progresses have been achieved in the study of tracing urban atmospheric CO_2ff using ¹⁴C by Chinese scientists. The variation characteristics of urban CO_2ff at different temporal and spatial scales were obtained through the analysis of ¹⁴C in air， tree ring and annual plant samples. Our results show that the northern cities are the key points to reduce carbon emissions， and that the CO_2ff emissions can be reduced simultaneously by controlling atmospheric pollutant emissions， indicating a synergistic emission reduction. It was found that CO_2ff in Xi'an was mainly from local coal-burning emissions with the use of improved WRF-CHEM model and δ¹³C. Finally， the yearly CO_2ff traced by tree-ring ¹⁴C in Xi'an showed similar trends and amplitudes with the statistical data of carbon emissions， which indicates that the ¹⁴C tracing method and statistical method can be mutually validated to ensure the reliability of the data. In order to promote the ¹⁴C trace study to serve the national carbon emission reduction task， we suggest that the urban atmospheric Δ¹⁴CO₂ observation network should be established as soon as possible， and that this study should be enhanced with more scientists involved in it and more financial resources to support it.     

Analyses and calculation facts of the baroclinic term in synoptic-scale motion over tropics

Analyses are made of all terms in the vorticity equation for the atmosphere at low latitudes by using the scale analysis theory, with the result that for synotic-scale motion the baroclinic term, i. e. the twisting term and the vorticity vertical-transport term, approximates in order to the relative-vorticity advection, divergence and β term. With intensified atmospheric disturbance ratios of the β term to others become smaller while the others stay in more or less fixed proportions between them. This statement has been confirmed by the results of 22 typhoons calculated covering a large area in low latitudes. Besides, the baroclinic term for the genesis and development of 6 typhoons over 1979－1980 is calculated and the results ob-tained show that it has significant effect. Finally, the baroclinicity is shown not to be ignored in dealing with synoptics and dynamics of synoptic-scale systems such as typhoons and easterly waves.     

荧光催化动力分析法测定痕量钌

在碱性介质中,痕量Ru对邻羟基苯基荧光酮与H_2O_2的氧化还原反应有催化作用。据此,本文拟定了高灵敏测Ru的荧光催化动力学方法。实验操作简单,Ru的检出限为5×10~(-11)g/ml。     

一种新的非均匀断层模型及其振幅谱的特征

本文提出了一种弯曲断层面的非均匀断裂模型。我们把弯曲断层面简化为锯齿形状,当每个锯齿上的滑动是均匀的,同时具有均匀的位错传播速度时,可以得到问题的封闭形式的精确解。对于不同的齿数、齿倾角和场方位角,计算了体波辐射的振幅谱。研究发现,弯曲断层会使谱曲线出现异常的峰值,异常峰值的位置与齿数有关,随齿数的增加向高频方向移动。齿倾角的变化会引起振幅谱曲线上异常峰附近谱包络线的变化。不同方位的观测点处的振幅谱形状各不相同。仔细地将观测谱与理论谱对比,有可能使人们了解断层面的非平面性质。