Dynamics of Organic Carbon and Microbial Biomass in Alluvial Soil With Tillage and Amendments in Rice-wheat Systems

Rice-wheat cropping systems of the Indo-Gangetic plains (IGP) occupying 12 million ha of productive land are important for the food security of South Asia. There are, however, concerns that yield and factor productivity trends in these systems are declining/stagnating in recent years. Decrease in soil organic carbon is often suggested as a reason for such trends. A field experiment was conducted to study the soil organic carbon (SOC) and soil microbial biomass carbon (MBC) dynamics in the rice-wheat systems. Use of organic amendments and puddling of soil before rice transplanting increased SOC and MBC contents. Microbial biomass carbon showed a seasonal pattern. It was low initially, reached its peak during the flowering stages in both rice and wheat and declined thereafter. Microbial biomass carbon was linearly related to SOC in both rice and wheat indicating that SOC could be used as a proxy for MBC.     

声波团聚技术消除储能电站火灾烟雾的实验研究

为探究声波团聚技术对于储能电站火灾烟雾的清除作用,搭建了声波团聚实验台,利用炭黑颗粒气溶胶模拟储能电站的火灾烟雾,探究了声波频率、声压级和初始烟雾浓度等参数对声波团聚效果的影响.结果表明:在声压级为140 dB、频率为1 000 Hz的声波作用下,在20 s时间内火灾烟雾的透光率从22％提高到了90％;当声压级由135...     

粉煤灰浸出液入渗土壤过程中的水岩作用研究

为明确粉煤灰浸出液对地下水环境的影响,依据饱水土柱试验,利用质量平衡模型,对比研究了灞桥电厂粉煤灰浸出液和清水入渗土壤过程中的水岩作用.研究表明,虽然粉煤灰浸出液和清水入渗土柱的渗出液水化学特征存在明显差异,但入渗水的水质对渗出液的时间变异性影响较小.矿物的溶解沉淀作用及Ca-Na离子交换等水岩作用对浸出液和清水入渗过程中的化学反应及水化学形成产生重要影响.高浓度的粉煤灰浸出液比清水溶解了土壤中更多的可溶盐,使土壤的渗透系数增大,增加了地下水污染风险.     

Sensitivity of the DERMA long-range Gaussian dispersion model to meteorological input and diffusion parameters

The Danish Emergency Response Model of the Atmosphere (DERMA) is described and applied to the first ETEX experiment. By using analysed low-resolution numerical weather-prediction data from the global model of the European Centre for Medium-range Weather Forecast (ECMWF) as well as higher-resolution data from two versions of the High Resolution Limited Area Model (HIRLAM), which are operational at the Danish Meteorological Institute (DMI), the sensitivity of DERMA to the resolution of meteorological data is analysed by comparing DERMA results with concentration measurements. Furthermore, the sensitivity to boundary-layer height and diffusion parameters is studied. These parameters include the critical bulk Richardson number, which is used to estimate the atmospheric boundary-layer height, the horizontal eddy diffusivity and the Lagrangian turbulence time scale. The parameters, which provide the best performance of DERMA, are 0.25 for the critical bulk Richardson number, 6×10³ m² s^-1 for the horizontal eddy diffusivity, and 3 h for the Lagrangian time scale. DERMA is much more sensitive to boundary-layer parameters when using high-resolution DMI-HIRLAM data than when using data of lower resolution from the ECMWF. Finally, the bulk Richardson number method of boundary-layer height calculation applied to DMI-HIRLAM data is verified directly against routine radiosondes released under the tracer gas plume. The boundary-layer height estimates based on analysed NWP model data agree well with observations, and the agreement deteriorates as a function of forecast length.     

Bulgarian emergency response models–validation against ETEX first release

In the paper, the performance of two Bulgarian dispersion models is tested against European Tracer Experiment (ETEX) first release data base. The first one is the LED puff model which was the core of the Bulgarian Emergency Response System during all releases of ETEX. The second one is the newly created Eulerian dispersion model EMAP. These models have two important features: they are PC-oriented and they use quite a limited amount of input meteorological information. First, a number of runs with various source configurations are made on meteorological data produced by ECMWF. The aim of these runs is to verify the models’ ability to simulate reliably ETEX first release. To this end, a set of statistical criteria selected in ATMES (Atmospheric Transport Models Evaluation Study, see Klug et al., 1992 are used. The best runs for both models are obtained when the source is presented as a column towering from the ground to heights of 400–700 m. These runs took part in the second phase of ETEX (ETEX-II), the so called ATMES-type exercise where EMAP ranked ninth and LED - fourteenth among 34 models. Here, additional sets of EMAP are presented where in the first run the value of the horizontal diffusion coefficient is varied and in the other runs different meteorological data sets are tested. The results obtained from the first run show that the values of K_h=4–6×10⁴ m² s^-1 produce fields which fit experimental data best. The other sets of runs show that the higher the frequency of the meteorological data, the better the simulation. The results can be improved by linear interpolation of the meteorological parameters with time, the best fitting obtained with interpolation at each time step.     

基于实验与仿真的三维水下气体泄漏预测与安全评估研究

水下气体羽流特性是海底气体泄漏风险评估的重要基础。为准确预测水下气体羽流行为,基于计算流体动力学(CFD)方法,建立1种考虑气体卷吸湍流特性的三维水下气体羽流数值预测模型;采用欧拉-欧拉流体体积模型捕捉气液作用界面,以大涡模拟(LES)方式预测羽流上浮及卷吸过程中的湍流特性,从而实现对水下气体羽流行为的预测;搭建小尺度实验平台,对比仿真与实验条件下的气体羽流形态,验证数值模型的可行性及预测精度;应用建立的数值模型对工程条件下的水下气体泄漏事故进行预测和评估,以某浅层气井喷事故为例,评估水下气体羽流上浮时间、海面影响范围和涌流高度。结果表明:基于欧拉多相流与大涡模拟的数值模型对水下气体羽流预测结果与实验具有较好的吻合度,该模型能够较好捕捉羽流的湍流特性,可为水下气体泄漏羽流行为评估提供参考。     

地空导弹发射飞行可靠度试验剖面生成方法

本研究在明确地空导弹武器装备寿命剖面、任务剖面的基础上,利用已经收集到的19发导弹的冲击、振动遥测数据和6发导弹的弹上温度遥测数据以及已经掌握的大量地面温度、电应力数据,进行数据分析与归纳,生成地空导弹环境剖面,并根据我国现有试验条件,将其转化为可靠性试验剖面。     

海南马尾藻海藻酸钠的提取工艺及表征

采用正交试验方案首次研究了海南马尾藻海藻酸钠的提取工艺,得出最佳的提取工艺条件:Na2CO3浓度为2%、消化温度为55℃、消化时间为3h,海藻酸钠提取率最高达40.4%.用FTIR表征发现,提取的马尾藻海藻酸钠与市场售的海带海藻酸钠在结构上差别不大,同时测得提取海藻酸钠的分子量为36万、粘度为185mPa.S,高于GB1976-80要求的150mPa.S.     

污泥处理及有效利用

在调研国内外关于污泥处理及有效利用的文献资料的基础上,分析天津开发区污水处理厂污染特性和成份并进行污泥发醇模拟试验,根据污泥特性并结合开发区土壤理化性质特点,提出开发区污泥处理及有效利用的可行方案。     

不同药物防疫程序对三黄鸡育雏效果的比较研究

采取3个不同药物防疫程序对2 100羽三黄鸡进行了为期8周的育雏试验,其成活率均在96%以上,其中试验2组效果最好,成活率达98.42%,此预防程序可在实际生产中应用。