利用有效微生物菌群控制蓝藻水华研究

蓝藻水华污染在我国和世界都呈现迅猛的发展趋势,如何治理是环境科学研究领域的热点。2008年7～8月在北京市延庆县妫水湖的现场围隔水体中,通过投加筛选和培养土著有效微生物菌群(EM菌),对控制蓝藻水华污染形成的效果进行研究。结果表明,与对照相比,投加EM菌不仅可以控制蓝藻水华的暴发,使蓝藻生物量降低70%以上,而且可以快速降低水体中的氮和磷浓度,因此,明显控制了蓝藻水华的形成,在治理湖泊蓝藻水华污染方面具有重要的应用前景。     

Moisture transfer modeling during solar drying of potato cylinders considering shrinkage

In the present work, the thin layer drying kinetics of potato during natural convection solar drying was investigated experimentally. Cylindrical potato samples with length 50 mm and varying diameter of 8, 10 and 13 mm were dried in an in-house designed and fabricated laboratory scale mixed-mode solar dryer. Thirteen different thin-layer mathematical models were fitted to the experimental moisture ratio (MR) data. The obtained results indicated that the Modified Page model could satisfactorily describe the drying curve of potato cylinders with higher value of R² and lower values of RMSE and χ². The shrinkage parameter is incorporated in the analytical diffusion model to study the moisture transfer mechanism of potato cylinders. It was observed that the values of effective diffusion coefficient (D_eff) and convective mass transfer coefficient (h_m) are overestimated in the range of 85.02–90.27% and 39.11–45.11% for the range of sample diameter examined, without considering the shrinkage effect in the mass transfer analysis. A Multiphysics approach was adopted in this study to get insight into the drying behavior of potato cylinders in terms of food-moisture interactions during the solar drying process. The predicted results of MR are in close agreement with the experimental data. Moreover, the anisotropic behavior of shrinkage as well as the moisture distribution inside the potato cylinder was very well described by Multiphysics model.     

不同含水量细砂介质中挥发苯的有效扩散系数研究

挥发性有机污染物在土壤多孔介质中的有效扩散系数是土壤气相抽提(soil vapor extraction,SVE)传质过程中的一个重要参数.笔者以苯为研究对象,采用土柱扩散试验,对不同含水量条件下挥发苯在细砂介质中的有效扩散系数和扩散规律进行研究.结果表明,对于吸附型矿物含量少的细砂介质,含水量大小在一定程度上影响了挥发苯的扩散过程.含水量在50 g·kg-1时,扩散最快;低于50 g·kg-1时,随含水量增大扩散能力增强;高于50 g·kg-1时,扩散能力则随含水量增大而减弱.同一扩散柱中,随着扩散距离增加,挥发苯的有效扩散系数增大,这可能与其蒸汽分压降低有关.     

新型高效气体扩散电极的制备与性能

评述了原位产生H₂O₂的电化学法污水处理技术中使用的主要电极，研究了用石墨制备高效气体扩散电极的方法。对石墨用HNO₃与H₃PO₄的混合液改性，石墨与聚四氟乙烯的质量比为2∶1，电极经350℃煅烧1 h，对溶解O₂还原产生H₂O₂的催化活性最高。仅在pH值很低时，电极的活性较差，在pH=3～9时，电极的活性受pH值变化影响较小。在pH=3时电解150 min，电极的电流效率始终高于72%，H₂O₂浓度达到了274.5 mg/L。     

水样中常见金属离子的快速测定

研究了用高效毛细管电泳对自来水水样中常见金属离子的快速测定方法。结果表明,K+、Na+、Li+、Ca2+、Mg2+、Ba2+、Sr2+7种离子在8 min内可全部分离,回收率为98.0%~103.3%。峰面积和迁移时间的相对标准偏差分别在3.2%和1.1%以下,重现性较好,具有较高的检测灵敏度。     

尾矿坝溃坝模型研究及应用

根据多个大坝的实际溃决资料,提出尾矿坝溃坝的数学模型,该模型考虑尾矿的物理力学性质及其在流动中的变形,适合溃坝砂流下泄流量变幅大的特点。并就尾矿坝溃坝后泥石流对坝下游的影响提出预测的方法,该方法确定了泄砂总量、溃坝口平均宽度、坝址最大砂流量、坝址流量过程线等溃坝的重要参数。最后利用数学模型对某尾矿库溃坝砂流进行了预测,并指出该坝下游人员的撤离高程,为防灾减灾以及保护人民生命财产安全等起到了积极作用。     

Pulling force prediction using neural networks

Purpose. In ergonomics and human factors investigations, pulling force (PF) estimation has usually been achieved using various types of biomechanical models, and independent approximation of PF was done with the help of upper extremity joints. Recently, multiple regression methods have gained importance for task-relevant inputs in predicting PF. Artificial neural networks (ANNs) also play a vital role in fitting the data; however, their use in work-related biomechanics and ergonomics is inadequate. Therefore, the current research aimed to accomplish comparative investigation of ANN and regression models by assessing their capacity to predict PF values. Methods. Multipositional PF data were acquired from 200 subjects at three different handle heights and body locations. ANN and regression models were formed using a random sample of three subsets (75% training, 15% selection, 10% validation) for proving the outcomes. Results. The comparison of ANN and regression models shows that the predictions of ANN models had a profoundly explained variance and lower root mean square difference values for the PF data at three handle heights. Conclusions. These outcomes advise that ANNs offer a precise and robust substitute for regression methods, and should be considered a useful method in biomechanics and ergonomics task assessments.     

Understanding the effects of different social data on selecting priority conservation areas

Conservation success is contingent on assessing social and environmental factors so that cost‐effective implementation of strategies and actions can be placed in a broad social–ecological context. Until now, the focus has been on how to include spatially explicit social data in conservation planning, whereas the value of different kinds of social data has received limited attention. In a regional systematic conservation planning case study in Australia, we examined the spatial concurrence of a range of spatially explicit social values and land‐use preferences collected using a public participation geographic information system and biological data. We used Zonation to integrate the social data with the biological data in a series of spatial‐prioritization scenarios to determine the effect of the different types of social data on spatial prioritization compared with biological data alone. The type of social data (i.e., conservation opportunities or constraints) significantly affected spatial prioritization outcomes. The integration of social values and land‐use preferences under different scenarios was highly variable and generated spatial prioritizations 1.2–51% different from those based on biological data alone. The inclusion of conservation‐compatible values and preferences added relatively few new areas to conservation priorities, whereas including noncompatible economic values and development preferences as costs significantly changed conservation priority areas (48.2% and 47.4%, respectively). Based on our results, a multifaceted conservation prioritization approach that combines spatially explicit social data with biological data can help conservation planners identify the type of social data to collect for more effective and feasible conservation actions.     

某铀矿山废石场及尾砂库氡污染调查

通过对某退役铀矿山的 14个废石堆放场及 3个尾砂库氡析出率的测量及内照射剂量的估算 ,表明 ,只有一个废石场的氡析出率超过国家规定的管理限值水平 ;尾砂库的氡析出率较高 ,个别测点的氡析出率超出管理限值水平近 7倍 ;因氡析出而使当地居民额外所受的年最大有效剂量当量为 0 0 5 8mSv。指出在尾砂库表面覆盖黄土 ,可以有效降低氡析出水平 ,当覆盖厚度达 0 5m时 ,可将氡析出水平降低 84%以上。     

沈抚灌渠污水预处理实验研究

以砾石为填料采用生物滤池法和以纤维束为填料采用生物接触氧化法，分别预处理沈抚灌渠污水。试验结果表明，在水力停留时间在3．5h，控制气水比分别为5：1和4：1的反应条件下，砾石填料对COD和NH3-N的平均去除率分别为53．9％和53．6％；纤维束软填料对COD和NH3-N的平均去除率分别为55．7％和47．7％。前者对COD和NH3-N的处理效果都达到了预定要求，而后者对NH3-N的处理效果没有达到要求。