基于SWE的传感规划服务研究与实现

文章首先基于SWE详细分析了传感规划服务应完成的核心操作,然后重点阐述了基于SWE的传感规划服务原型系统的设计,包括系统的数据交互和系统体系结构的设计。并详细阐述了每一层设计的实现,最后基于一个红外楼宇监控无线传感器网络实现了SPS原型系统,并进行了试验,实验结果表明该原型系统中实现的SPS的核心操作能够较好地为用户请求任务提供规划服务。     

Critical review on recent developments in solventless techniques for extraction of analytes

The most recent contributions on solventless extraction techniques have been reviewed. This paper deals with those techniques that use solid phases, such as solid-phase microextraction, liquid phases, such as single-drop microextraction and hollow-fibre liquid-phase microextraction, and subcritical fluids, such as subcritical water extraction. In all cases, the most recent publications have been critically studied. Direct extraction and derivatization processes to facilitate the extraction of analytes in different areas have been included. Hyphenated approaches, if available, are also included in this review. Comparison of techniques organized by analytes and matrices also enhances this critical overview of solventless techniques.     

An overview of sample preparation and extraction of synthetic pyrethroids from water,sediment and soil

The latest developments in sample preparation and extraction of synthetic pyrethroids from environmental matrices viz., water, sediment and soil were reviewed. Though the synthetic pyrethroids were launched in 1970s, to the best of authors’ knowledge there was no review on this subject until date. The present status and recent advances made during the last 10 years in sample preparation including conservation and extraction techniques used in determination of synthetic pyrethroids in water, sediment and soil were discussed. Pre- and post-extraction treatments, sample stability during extraction and its influence upon the whole process of analytical determination were covered. Relative merits and demerits including the green aspects of extraction were evaluated. The current trends and future prospects were also addressed.     

Comparison of extraction techniques for the isolation of explosives and their degradation products from soil

A comparison of four extraction techniques used for the isolation of 14 explosive compounds (Method 8330-Explosives) from spiked soil samples is described. Soxhlet warm extraction (SWE), pressurized solvent extraction (PSE), microwave assisted extraction (MAE) and supercritical fluid extraction (SFE) were included. The effects of basic extraction conditions – i.e. type of extraction solvent, temperature, pressure, and extraction time – were investigated. The best extraction recovery of the monitored compounds from spiked soil was obtained using pressurized solvent extraction. Recoveries of explosives using the PSE technique were in the range from 65 to 112%. Extraction recoveries by Soxhlet warm extraction and supercritical fluid extraction reached 65–99% and 52–75%, respectively. The lowest extraction recoveries (28–65%) were obtained using microwave assisted extraction. A very low extraction recovery for tetryl was observed in all cases but the best results were achieved by pressurized solvent extraction (58%).     

Comparison of extraction techniques for isolation of steroid oestrogens in environmentally relevant concentrations from sediment

The comparison of four extraction techniques for isolation of five native and one labelled steroid oestrogens from sediment was described. The three conventional extraction techniques Soxhlet warm extraction (SWE), accelerated solvent extraction (ASE), microwave-assisted extraction (MAE) and a promising technique QuEChERS were tested for isolation of low environmentally relevant oestrogen concentrations using different extraction conditions. The least expensive and time-consuming method QuEChERS provided the best extraction recoveries (53–84%) from all techniques. MAE achieved the highest recovery from conventional techniques for less polar oestrogens using dichloromethane: acetone 3:1 mixture as an extraction solvent (50–71%), but for extraction of the whole group of oestrogens including more polar estriol acetone or methanol must be used. ASE provided higher extraction recoveries using dichloromethane at 60°C (53–74%) for less polar oestrogens. However, the repeatability of results was unsatisfactory and recoveries using other extraction conditions were lower than for MAE. The most time-consuming SWE achieved the worst extraction recoveries and for isolation of low oestrogen concentrations from sediments, it is completely unsuitable.     

亚临界水萃取-高效液相色谱法测定聚碳酸酯水杯中双酚A和苯酚的迁移量

建立了亚临界水萃取-高效液相色谱同时测定聚碳酸酯(PC)水杯中双酚A和苯酚迁移量的方法。选择萃取温度120 ℃、萃取压力6.89 MPa(1000 psi)、静态萃取时间1 h、萃取1次对11种样品进行测定。双酚A的迁移量为6.81～11.16 μg/g。5种样品中未检出苯酚,其余样品中苯酚迁移量为3.25～6.08 μg/g。在优化的测定条件下,双酚A和苯酚在8 min内达到基线分离。双酚A和苯酚分别在0.05～20 mg/L和0.02～20 mg/L范围内线性关系良好,相关系数(r)均大于0.9997,检出限分别为7.6 μg/L和2.0 μg/L。日内及日间的重复性(以RSD计)分别小于5.21%及11.63%。传统的浸提法结果表明长时间浸提会使PC材料发生微弱水解。相比传统的浸提法,该方法的萃取效率提高了49～106倍。该方法简便、快速、环保,可用来测定PC水杯中双酚A和苯酚的迁移量。     

网络化传感器接口相关标准概述 网络化传感器接口相关标准概述

总结了传感器接口标准化方面的相关工作,重点分析IEEE 1451标准和SWE的研究问题和关键技术的解决思路,在此基础上提出若干值得继续研究的新问题.     

A Newton multigrid method for steady-state shallow water equations with topography and dry areas

A Newton multigrid method is developed for one-dimensional (1D) and two-dimensional (2D) steady-state shallow water equations (SWEs) with topography and dry areas. The nonlinear system arising from the well-balanced finite volume discretization of the steady-state SWEs is solved by the Newton method as the outer iteration and a geometric multigrid method with the block symmetric Gauss-Seidel smoother as the inner iteration. The proposed Newton multigrid method makes use of the local residual to regularize the Jacobian matrix of the Newton iteration, and can handle the steady-state problem with wet/dry transition. Several numerical experiments are conducted to demonstrate the efficiency, robustness, and well-balanced property of the proposed method. The relation between the convergence behavior of the Newton multigrid method and the distribution of the eigenvalues of the iteration matrix is detailedly discussed.     

Approximate traveling wave solution for shallow water wave equation

Reconstruction of Variational Iteration Method (RVIM) is used for computing the coupled Whitham-Broer-Kaup shallow water. Then RVIM solution is verified against exact one and is compared with powerful approximate solutions, the Homotopy Perturbation Method (HPM) and Homotopy Analysis Method (HAM). The existent error of the methods is computed and convergence of the RVIM solution has been presented. Results obtained expose effectiveness and capability of this method to solve the nonlinear systems in mechanics, analytically.     

Extracting and trapping biogenic volatile organic compounds stored in plant species

Biogenic volatile organic compounds (BVOCs), released by practically all plants, have important atmospheric and ecological consequences. Because BVOC-emission measurements are especially tedious, complex and extremely variable between species, two approaches have been used in scientific studies to try to estimate BVOC-emission types and rates from plant species. The first, which has known little success, involves grouping species according to plant-taxonomy criteria (typically, genus and family). The second involves studying the correlation between BVOC content and emission (i.e. how leaf content could be used to estimate emissions). The latter strategy has provided controversial results, partly because BVOCs are amazingly chemically diverse, and, as a result, techniques used to study plant BVOC content, which we review, cannot be equally adequate for all analytes.In order to choose an adequate technique, two patterns must be distinguished. Specifically stored compounds - mainly monoterpenes and sesquiterpenes that dominate the essential oil obtained from a plant - are permanently and massively present in specific storage structures (e.g., secretory cavities, trichomes) of the order of μg/g-mg/g and usually allow emissions to occur during stress periods when terpenes are weakly synthesized. These BVOCs can be studied directly through traditional extraction techniques (e.g., hydrodistillation) and novel techniques (e.g., application of microwaves and ultrasound), and indirectly by trapping techniques involving the collection, within adsorbent material, of BVOCs present in the headspace of a plant.Non-specifically stored compounds (e.g., isoprene, 2-methyl-3-buten-2-ol, and, in species without storage structures, monoterpenes and sesquiterpenes) can only be temporarily accumulated in leaf aqueous and lipid phases in small concentrations of the order of ng/g. As a result, studying their concentration in leaves requires the use of trapping techniques, more sensitive to trace amounts. Unlike for specifically stored BVOCs, knowledge of the concentration of non-specifically stored BVOCs cannot provide any information regarding the emission potential of a species but, instead, provides crucial information to understand why BVOC emissions may be uncoupled from the physiological processes that drive their synthesis.We describe both extracting and trapping techniques and discuss them in terms of the technical choices that may cause losses of thermolabile constituents, chemical transformations, different volatile recoveries and suitability to represent plant content of BVOCs faithfully. The second part of this review addresses technical shortcomings and biological and environmental factors that may alter the correlations between BVOC content and emission from plants.