环境空间分析中常用采样方法及其对空间结构表达的影响

采用几种采样方法在不同的采样密度下分别在两套模拟数据集上进行模拟采样，并以实验半变异函数为结构分析工具探讨了采样方案对具有不同空间分布特征数据的空间结构表达的影响。研究发现，采样密度与采样方法的选取都对空间结构的表达有显著影响。     

MODEL DEVELOPMENT FOR CONJUNCTIVE USE STUDY OF THE SAN JACINTO BASIN,CALIFORNIA1

ABSTRACT: A two-layered confined-unconfined numerical model for flow and mass transport is developed for the San Jacinto Basin. The model structure is determined by the geological structure of the Basin and model parameters are calibrated using 20 years of historical records. The total number of historical head observations used for the flow model calibration is 1,117 and the total number of the estimated parameters is 91. The two-layered transport model is also calibrated using historical water quality records. Sensitivity analysis of the flow model shows that only 68 parameters (out of a total of 91) are relatively sensitive and reliable. However, the unreliable parameters (23 of them) are found to be insensitive and thus not significant to the prediction and management of conjunctive use of surface water and ground water. The developed flow model has been used to study the two proposed artificial recharge scenarios for the San Jacinto Basin. We have found that during a relatively dry condition, an artificial recharge rate of 80 acre-ft/day can be achieved during the recharge period October through January. However, for a relatively wet condition, only 80 percent of the proposed rate can be effectively stored in the Basin during these months.     

LINEAR PROGRAMS FOR NONLINEAR HYDROLOGIC ESTIMATION1

ABSTRACT: The minimization of the sum of absolute deviations and the minimization of the absolute maximum deviation (mini-max) were transformed into equivalent linear programs for the estimation of parameters in a transient and linear hydrologic system. It is demonstrated that these two methods yield viable parameter estimates that are globally optimal and reproduce properly the timing and magnitude of hydrologic events and associated variables such as total runoff. The two linear estimation methods compared favorably with the popular least-squares nonlinear estimation method. The generality of the theoretical developments shows that linear program equivalents are adequate competitors of nonlinear methods of hydrologic estimation and parameter calibration.     

Mater-Bi: Properties and biodegradability

This paper examines the biodegradability of a new class of materials based on starch and vinylalcohol copolymers, which have been commercialized under the Mater-Bi trademark. Particular attention is given to the biodegradation process for natural and synthetic components of different Mater-Bi grades for film blowing in an aerobic respirometric test, in a SCAS (semicontinuous activated sludge) test, and by submersion in lake water. The correlation between morphology and biodegradation behavior is also considered. Taking into account the prior art on biodegradation of insoluble substrates, a two-step mechanism is proposed for Mater-Bi products.     

Spatial Calibration and Temporal Validation of Flow for Regional Scale Hydrologic Modeling1

Abstract: Physically based regional scale hydrologic modeling is gaining importance for planning and management of water resources. Calibration and validation of such regional scale model is necessary before applying it for scenario assessment. However, in most regional scale hydrologic modeling, flow validation is performed at the river basin outlet without accounting for spatial variations in hydrological parameters within the subunits. In this study, we calibrated the model to capture the spatial variations in runoff at subwatershed level to assure local water balance, and validated the streamflow at key gaging stations along the river to assure temporal variability. Ohio and Arkansas‐White‐Red River Basins of the United States were modeled using Soil and Water Assessment Tool (SWAT) for the period from 1961 to 1990. R² values of average annual runoff at subwatersheds were 0.78 and 0.99 for the Ohio and Arkansas Basins. Observed and simulated annual and monthly streamflow from 1961 to 1990 is used for temporal validation at the gages. R² values estimated were greater than 0.6. In summary, spatially distributed calibration at subwatersheds and temporal validation at the stream gages accounted for the spatial and temporal hydrological patterns reasonably well in the two river basins. This study highlights the importance of spatially distributed calibration and validation in large river basins.     

高职食品工艺学实验室建设和教学方法的探讨

实验教学是高职教育中不可缺少的环节,多媒体课件的制作与演示性实验教学作为重要的教学方法可以应用于高职食品工艺学的辅助教学.本文介绍了食品工艺实验室设计及教学方法的要求和特点,为使食品工艺实验室实现可持续发展,该实验教学必须与其他学科结合,实验项目必须反映加工新技术,培养学生自发动手动脑能力.     

Insight into the interaction between trimethoprim and soluble microbial products produced from biological wastewater treatment processes

Soluble microbial products (SMPs),dissolved organic matter excreted by activated sludge,can interact with antibiotics in wastewater and natural water bodies.Interactions between SMPs and antibiotics can influence antibiotic migration,transformation,and toxicity but the mechanisms involved in such interactions are not fully understood.In this study,integrated spectroscopy approaches were used to investigate the mechanisms involved in interactions between SMPs and a representative antibiotic,trime...     

交通建设工程安全评价技术现状及趋势研究

综述我国交通建设工程安全生产现状,详细描述常用安全评价技术在我国交通建设工程中的实用状况,对专家论证、安全检查表、作业条件危险性评价等常用安全评价方法的适用范围及优缺点加以分析。系统研讨安监系统及建设部门制定涉及安全评价的相关规定及其应用情况。对国内外工程建设安全评价方法的定量化、软件化等研发进展进行讨论,同时对我国交通建设工程安全评价技术发展趋势给以展望。     

高氢分压下厌氧颗粒污泥演变过程研究

为了探究厌氧颗粒污泥用于氢辅助原位生物法沼气提纯的可行性，在高氢分压ASBR中对厌氧颗粒污泥演变过程进行了考察，包括反应器性能和厌氧颗粒污泥特性变化情况.结果表明，在进水COD负荷低于5g/（L·d）时，氢辅助原位生物法沼气提纯中高氢分压、高进水COD负荷和高剪切力新环境促使厌氧颗粒污泥向小粒径方向演变，系统运行性能良好、高效，此时厌氧颗粒污泥可以通过营造具有极低氢分压的微环境强化基于HIT（种间氢传递）途径丙酸降解；但随着进水COD负荷进一步提高，超过6g/（L·d）时，系统出现不可控的丙酸积累.因此，需要寻求其他技术手段来缓解更高进水COD负荷条件下氢辅助原位生物法沼气提纯系统中丙酸积累问题.     

A groundwater flow model for water resources management in the Ismarida plain,North Greece

This paper presents the development of a regional flow simulation model of the stream–aquifer system of Ismarida plain, northeastern Greece. It quantifies the water budget for this aquifer system and describes the components of groundwater and the characteristics of this system on the basis of results of a 3-year field study. The semiconfined aquifer system of Ismarida Lake plain consists of unconsolidated deltaic clastic sediments, is hydraulically connected with Vosvozis River, and covers an area of 46.75 km². The annual precipitation ranges in the study area from 270 to 876 mm. Eighty-seven irrigation wells are densely located and have been widely used for agricultural development. Groundwater flow in this aquifer was simulated with MODFLOW. Model calibration was done with observed water levels, and match was excellent. To evaluate the impacts of the current pumping schedule and propose solutions, four management scenarios were formulated and tested with the model. Based on model results, the simulated groundwater budget indicates that there must be approximately 33% decrease of withdrawals to stop the dramatic decline of groundwater levels. The application of these scenarios shows that aquifer discharge to the nearby river would be very low after a 20-year period.