Spatial and temporal trends in soil salinity for identifying perched and deep groundwater systems

Characterization of spatial and temporal variability in water flow and solute transport to foster better land management in salt‐affected landscapes requires direct hydrological observation, for example using suites of nested piezometers and dip wells. Such methods are costly to install and produce data with low spatial density, so are not ideal for supporting within‐field scale land management decisions. We present a new methodology to characterize water‐flow systems in salt‐affected landscapes using trends in shallow (<1 m) down‐profile soil salinity based on electrical conductivity of saturated paste extract (EC_se) and salts (that is the water extractable major ions of Ca, K, Mg, Na, P, Cl and S mg/kg) from a range of topographic settings. This involved coupling seasonal (late winter and late summer) salinity trends with clay percent (for soil morphology) and terrain patterns to understand the connectivity between perched and deep groundwater systems in a 120 ha catchment in the Mount Lofty Ranges, South Australia. From investigations at 19 sites in the catchment comprising toposequences or paired sites (in close proximity, but in different topographic settings), soil salinity trends revealed four hydro‐pedological systems: (i) a perched freshwater system with no hydraulic connectivity to the deep groundwater in upper slopes, (ii) an intermediate system comprising perched freshwater connected to a deep groundwater system in mid and upper slopes, (iii) a deep groundwater system in upper slopes, and (iv) a deep groundwater system in lower slopes. Although most of the 19 sites proved non‐saline, seasonal changes in EC_se and ion concentration along with topography and soil morphology were sufficient to characterize the hydro‐pedological systems. We assigned these systems to a newly developed salinity classification based on dominant soil‐regolith‐hydrological processes and designed to support land management decisions. Conceptual hydro‐pedological models for each system were constructed to illustrate and explain the important interactions in each and how these relate to the new salinity classification. We propose that the methodology based on seasonal monitoring offers a new approach to landscape‐based hydro‐pedological characterization without reliance on the traditional groundwater monitoring methods. The new method offers wider access to catchment hydro‐pedological information to support better land management decisions in sloping landscapes subject to salinity.     

Extended theoretical analysis of jet and atomization under high-pressure spraying and collecting dust mechanism of droplet

The atomization model about interaction of cavitation, turbulence and aerodynamics is put forward through the analysis about the control equation of jet disturbance, the computed result of the dispersive jet equation, according to the conceptual model of spray based on two-phase flow. The action of cavitation and turbulence formed inside nozzle are thought to lead to the first atomization near the nozzle exit, while the aerodynamic effect controls the following second atomization process. And the critical Weber number 〖BP(〗［We］=12(1+1.077Oh1.5)〖BP)〗 is taken as the judgment index for occurring of the second atomization or not. The critical velocity for liquid splitting into droplets is 60 m/s according to the analysis of break mode about liquid drop, furthermore, jet fragmentation and film fragmentation occurs in the first and second atomization respectively. The typical mechanism of dust capture by water-cloud is improved through the active collision theory of droplet to dust particle. It is considered that an optimal relationship exists between collection rate and droplet size when gas containing dust is unsaturated and its temperature is higher than that of liquid, moreover, low fluid velocity can be propitious to the collection of tenuous droplet to exiguous dust on the basis of the same liquid-gas ratio and the same quantity of droplets.     

塔里木河流域的景观生态系统与特征

塔里木河流域景观生态元素对比度高 ,结构简单 ,其模式是沙漠 (基 )—绿洲 (斑 )—河流、水渠 (廊道 )。景观生态系统具敏感性、不稳定性特征 ,水是景观元素转换的起博器。在生态环境建设时通过“共生”控制人类—环境系统 ,整合社会—经济—自然生态系统 ,加大保护湿地、绿洲的力度。景观生态结构精细解剖的技术支撑是现代高新技术 ,结构重建的理论的基础是景观生态学的基本理论。塔里木盆地周边绿洲处于不同构造地貌单元的交接过渡带 ,景观生态建设需要将其纳入盆—山耦合系统中进行研究。     

旅游循环经济的概念模型与发展模式研究

旅游循环经济是循环经济旅游业中的应用，是旅游经济发展的高级阶段。文章首先探讨了循环经济内涵，在分析循环经济与旅游业发展关系的基础上，界定了旅游循环经济的定义，并对旅游循环经济的构成要素进行了研究，最后提出了旅游循环经济的概念模型和发展模式。     

基于产品语义分析的自激对冲喷头概念设计

运用语义学的观点,分析了一种新型植保喷头—自激对冲喷头的概念设计,探讨产品语义分析在植保机械喷头设计中的应用。为此,阐述了产品语义学内涵,并基于信息传播理论将植保机械喷头设计的语义定义为能指与所指,进行了形式化的描述并定义了产品语义模型;通过社会、经济和技术三因素分析了植保喷头的产品机会,运用自然语言处理的产品语义表征方法,说明了产品语义分析在喷头概念设计中的运用,完成了自激对冲喷头概念设计,并试验验证该设计方案的可行性,从而为植保机械设计提供一种可行的技术方法。     

自然灾害的风险特征及风险管理模型的探讨

随着人口的增加和城市化的发展,自然灾害问题将更加严峻,理解自然灾害的风险特征比以往任何时期都显得更加重要.在认识自然灾害风险的特点和风险概念的基础上,本着科学与实用,通用与开放的原则,构建一个由风险鉴别、风险分析、风险评估和风险处理四个模块组成自然灾害风险管理模式,该模型具有灾害风险管理的基本思路和系统方法,能够为灾害风险管理提供行动指南.     

Computer Aided Analysis Tool for Building Energy Efficiency in Conceptual Design Stage

Conceptual design is one of the most important stages in building design, and energy efficiency analysis is one of the key issues in building conceptual design stage. The existing energy efficiency analysis methods and tools require inputing large number of parameters. However, the detail information of most parameters is not identified at the stage of conceptual design. And the current prevailing energy consumption simulation methods and tools are not appropriate at the stage of conceptual design. The proposed method can be used to compare the energy efficiency of multi strategies at the conceptual design phase. Minimum data were required to be input for achieving the optimal building design scheme. The method can provide a solution to the gap between the rapid building design cycle and the sustainable development demand in China.     

A framework for assessing irrigation performance

A comprehensive framework for conceptualizing irrigation performance is presented which, by clarifying relationships among the many incommensurate approaches to performance assessments, can provide the basis for more systematic comparative assessments of irrigation. Irrigation systems are carefully defined, and their relationships to broader agricultural and socioeconomic systems specified in terms both of goals and of inputs and outputs. Goals are seen as crucial to performance assessments, and the existence of many sometimes conflicting goals requires both specification of whose goals are being considered and clarification as to whether the goals are related to inputs, to outputs or to efficiency. Assessments can be categorized according to their purpose, with significant differences among those that monitor operational performance, those that facilitate interventions to improve performance, and those that promote accountability within an operating agency. Assessments also differ in the types of performance measures used. Three distinct categories of performance measures are identified: process measures, which relate to a system's internal operations; output measures, which focus on a system's final output; and impact measures, which pertain to the effects that the system's outputs induce in its larger environment. Performance measures are distinguished from performance standards which may be established from a variety of sources.Earlier versions of this paper were presented at the Symposium on Performance Evaluation of Irrigation systems held at the International Irrigation Management Institute, Colombo, Sri Lanka on November 23, 1989, and at a Workshop on Irrigation Performance held in Pangbourne, England, February 15–16, 1990.     

景观工程设计的"概念"释义方法研究

通过在实际工程设计中应用概念设计思维和表达方法的探索和研究,从逻辑学和语言学的角度提出了概念产生、发展和表达的命题设计方法及实际应用途径.     

Indicators of soil quality and crop productivity assessment at a long-term experiment site in the lower Indo-Gangetic plains

Deterioration of soil quality under resource-intensive modern agriculture in the face of global climate change poses a huge risk to food security. Because of the complex nature, estimators of soil quality often rely upon a limited set of soil attributes, along with statistical data reduction techniques, for developing quality indices, whilst overlooking biological aspects and regional climatic variability. This study screened the most suitable soil quality indexing approaches for a rice-oilseed-based cropping system in the lower Indo-Gangetic plains (IGP). For this, surface soil samples (0–15 cm) were collected from an ongoing long-term fertilizer experiment with a rice-mustard-sesame cropping system in the IGP. The following treatments were assessed for their effect on soil quality: T₁-control, T₂-NPK (recommended NPK doses), T₃-NPKG (NPK + in situ green manuring), T₄-NPKGB (NPK + in situ green manuring + biofertilizer) and T₅-NPKF (NPK + farm yard manure FYM). We found that total organic carbon (TOC), β-glucosidase, CaCl₂ extractable S, alkaline KMnO₄ oxidizable N, activity of urease, amidase enzyme and mean weight diameter (MWD) were sensitive key indicators of soil quality. The NPKF treatment maintained the highest soil quality status (0.80–0.91), both under productivity and environmental protection goals, owing to the availability of decomposable carbon. Regression analysis showed a better agreement of equivalent rice yield with expert opinion (EO; R² = 0.89) than principal component analysis (PCA; R² = 0.76). Finally, we found that the expert opinion approach with the nonlinear scoring function was the best tool for soil quality assessment of the region.