Stochastic Transfer Function Model and Neural Networks to Estimate Soil Moisture1

Abstract: A practical methodology is proposed to estimate the three‐dimensional variability of soil moisture based on a stochastic transfer function model, which is an approximation of the Richard’s equation. Satellite, radar and in situ observations are the major sources of information to develop a model that represents the dynamic water content in the soil. The soil‐moisture observations were collected from 17 stations located in Puerto Rico (PR), and a sequential quadratic programming algorithm was used to estimate the parameters of the transfer function (TF) at each station. Soil texture information, terrain elevation, vegetation index, surface temperature, and accumulated rainfall for every grid cell were input into a self‐organized artificial neural network to identify similarities on terrain spatial variability and to determine the TF that best resembles the properties of a particular grid point. Soil moisture observed at 20 cm depth, soil texture, and cumulative rainfall were also used to train a feedforward artificial neural network to estimate soil moisture at 5, 10, 50, and 100 cm depth. A validation procedure was implemented to measure the horizontal and vertical estimation accuracy of soil moisture. Validation results from spatial and temporal variation of volumetric water content (vwc) showed that the proposed algorithm estimated soil moisture with a root mean squared error (RMSE) of 2.31% vwc, and the vertical profile shows a RMSE of 2.50% vwc. The algorithm estimates soil moisture in an hourly basis at 1 km spatial resolution, and up to 1 m depth, and was successfully applied under PR climate conditions.     

Spatial cost efficiency in waste paper handling: the case of corrugated board in Sweden

This paper analyzes the spatial cost efficiency of the Swedish legislation regarding waste disposal handling. We focus on the case of corrugated board and recognize that the different counties in Sweden possess different economic prerequisites in terms of waste paper recovery and utilization potential. We employ data for six corrugated board mills and 20 counties and a non-linear programming model to identify the least cost strategy for reaching the politically specified recycling target of a 65% recovery rate for corrugated board. That is, the total costs of recovering a minimum of 65% in each county are calculated and compared with the case when the country as a whole recovers 65% of all old corrugated board is collected but there exist no uniform target for each county. The conclusion is that from an efficiency point of view the recovery efforts should be concentrated to the highly populated and urbanized counties, and not be uniformly divided throughout the country. In the base case, the results suggest that the cost efficient county-specific recovery rates should range from 51 to 72%.     

涂层大气腐蚀的模糊综合评定

此文将模糊理论应用于涂层的大气腐蚀试验,针对对比性腐蚀试验结果,提出了涂层保护性能大气腐蚀模糊综合评定方法。本法具有简捷、迅速、准确等优点。     

铅芯橡胶支座等效线性分析模型参数的研究

针对目前铅芯橡胶支座等效线性分析模型动力参数选取不够合理的现状,笔者通过对铅芯橡胶支座水平动态试验分析,系统研究了铅芯橡胶支座等效线性分析模型参数与其几何结构及外加动力荷载特性的关系.研究结果表明:铅芯橡胶支座等效线性分析模型参数(水平耗能、等效刚度及等效阻尼比)主要由其本身的几何构造及组成材料决定,且在往复加、卸载循环过程中具有较好的稳定性.笔者对试验数据进行数学统计分析,归纳出一些经验公式,为其等效线性化动力分析模型参数的合理选取提供了计算方法,从而提高其动力分析结果的安全性.     

模糊集值统计法在煤矿安全评价指标权值中的应用

应用模糊集值统计的理论,对煤矿安全评价中具有随机性和模糊性的指标进行数学分析,进一步改进了其权值的确定方法,使其更加符合实际情况,并对由此得出的权值进行了可靠性分析.通过实例表明,该方法克服了经典统计法的不足,提高了煤矿安全评价的实用性和科学性.     

小城镇灾害易损性分析与评估

随着我国城镇化进程的加快,小城镇的防灾减灾问题逐步引起社会的关注,而小城镇易损度分析和评价是灾害危险性评价的重要组成部分,也是小城镇决策部门制定防灾减灾规划的重要依据;笔者在综合分析了小城镇的自然易损性、经济易损性及社会易损性的基础上,选取相应的灾害指标和社会经济指标,应用多级模糊综合评判方法,对小城镇的易损程度作出了评估,从而为小城镇制定相应防灾、减灾对策提供科学依据.     

基于模糊颜色Petri网的表决DVP安全软件模型初探

把模糊计算理论和有色Petri网有机地结合起来,提出了一种模糊颜色Petri网诊断表决算法,把该算法应用于DVP的软件模型,使之具有故障容忍和表决的能力.笔者对以模糊颜色Petri网为核心的DVP软件模型表决算法进行了较为深入的探讨,该模型对提高软件系统的安全性和可靠性具有实际意义.     

生物法-人工湿地组合工艺处理小城镇混合污水研究

为适应小城镇污水处理高效、低耗、管理简单的要求,开展了生物法(水解酸化/生物接触氧化)-人工湿地组合工艺(A/BCO-CW)处理小城镇片区混合污水的研究。结果表明,A/BCO系统在停留时间为3～6 h条件下,对悬浮物和有机物有高的去除效率,COD、BOD5和TSS去除率分别达到63.1%、67.7%和66.2%,避免了人工湿地堵塞和提高处理效率,减少了所需湿地面积44%。全年运行结果表明,在0.30～0.59 m/d水力负荷率下,垂直流-表面流-水平潜流人工湿地组合系统对COD、BOD5和TSS平均去除负荷达9.4、5.1和7.2 g/(m2.d)(42%、71.2%和85.2%);COD、BOD5去除速率常数为74.6±12.1 m/y、166±30.5 m/y,这些数值均处于文献中k值范围的高量程内。A/BCO-人工湿地系统对COD、BOD5和TSS具有好的处理效果,出水水质能够稳定达到《地表水环境质量标准》(GB 3838-2002)的IV类水标准,2种处理方法有效组合起来,所开发的低成本、高效率、可持续运行的城镇废水处理组合系统,将会在实际应用尤其是高有机负荷污水处理中发挥良好效用。     

聚合物驱采出水中聚丙烯酰胺的微生物联合降解作用研究

通过对2株细菌的培养降解实验研究聚丙烯酰胺(hydrolyzed polyacrylamide,HPAM)降解菌对水环境下聚丙烯酰胺的降解作用,讨论协同降解机理。2株降解聚丙烯酰胺的菌株假单胞菌CJ419、枯草芽孢杆菌FA16在初始30℃废水样品上培养,定期测量细菌生物量和HPAM降解率。培养30 d后CJ419和FA16对聚合物的降解率最大值分别达到30.4%和25%,而以1∶1比例的混合菌降解率最大值达到80.3%。对2株菌胞外各组分研究表明:混合菌降解HPAM的机理主要由胞外降解酶系水解聚合物侧链基团导致HPAM降解为小分子物质,同时生长过程中降解菌还会释放非蛋白还原性物质引发氧化反应共同参与HPAM降解。     

Environmental indices in irrigation management

Irrigation management calls for objective criteria capable of representing the economy, reliability, and productivity of irrigation systems. These criteria must be compatible with long-term sustainability and conservation goals. The criteria representing the above goals are the economic effect of management on yield reduction, economic effect, and reliability referring to plant growth and operation of the network. In this study environmental indices are introduced to express the above criteria in quantitative terms. The inclusion of these indices at the farm and network level create a multicriteria framework for decision-making based on composite programming. An experimental study was conducted during the irrigation periods of 1989 and 1990 in Chania, Greece, concerning water delivered to 40 experimental plots, soil moisture content at the rootzone, and irrigation system operational failures. The data collected in real time were used for the calculation of the corresponding environmental indices. The variation in time and space is high and resulted in up to 62% of yield loss and low system performance (up to 7% of system temporal reliability). The study indicated that environmental indices could be incorporated to select alternatives and also to develop policies on water delivery. The final decision involves a trade-off analysis between cost of application and desired system performance. Measures of both primary objectives can be obtained using environmental indices that represent system operation aggregation at its basic levels (on farm and network).