Rain‐washing of foliar deposits of Dimilin®WP‐25 formulated in four different carrier liquids

Abstract

Dimilin^® WP‐25, a wettable powder formulation of diflubenzuron (DFB) [1‐(4‐chlorophenyl)‐3‐(2,6‐difluorobenzoyl) urea], was formulated in four different carrier liquids, viz., water; a light petroleum paraffinic oil, ID 585; a heavy paraffinic oil, Sunspray^® 7N; and a 1:2 mixture of a light petroleum aromatic solvent (Cyclosol^® 63) and canola oil; to provide four end‐use mixtures, Dim‐W, Dim‐585, Dim‐7N and Dim‐Cy‐C respectively, each containing 28 g of DFB per litre. Balsam fir branch tips clipped from greenhouse‐grown seedlings, and sugar maple branch tips clipped from field‐grown young trees, were exposed to uniform‐sized droplets (ranging in diameters from 135 to 190 μm) of the four end‐use mixtures which were atomized using a monodispersed droplet generator. Droplets were collected on the fir and maple branch tips and the initial residue per g fresh weight of foliage was determined by high‐performance liquid chromatography (HPLC). The branch tips were exposed to cumulative rainfall of 3, 6 and 10 mm at an intensity of 5 mm/h and at time intervals of 1, 12, 36 and 72 h after DFB treatment, to test the influence of ‘ageing’ of foliar residues on rainfastness. Foliar samples were collected for residue determination just before the onset of rainfall, and at 0.5 h post‐rain. DFB was quantified by the HPLC method. In the case of fir foliage, the Dim‐W formulation was the most susceptible to rain‐washing and the rainfastness did not increase with the ageing period of foliar deposits. In contrast, the three oil‐based mixtures showed greater rainfastness depending upon the carrier liquid and the ageing period. Rainfastness decreased in the order of Dim‐Cy‐C > Dim‐7N > Dim‐585 > Dim‐W. In contrast, the data on maple foliage indicated that the ageing of deposits increased the rainfastness of all the 4 end‐use mixtures. Dim‐585 was the most susceptible to rain washing, and rainfastness decreased in the order of Dim‐W > Dim‐Cy‐C > Dim‐7N > Dim‐585.     

采场通风方式与瓦斯运移规律研究

采场是煤矿生产的核心地带,而采场通风系统是确保采场作业安全,创造良好生产环境的重要环节。本文以采场风流流动及瓦斯运移理论为基础,通过现场试验、模型模拟试验及计算机模拟研究等方法,着重研究了中国常用的和有发展前途的走向长壁后退式U型通风方式、U+L型通曲方式、后退式Y型通风方式条件下采场风流流动及瓦斯运移规律。     

Production of radioactive particles for use in environmental studies

This paper presents an aerosol generation technique developed to produce dry aerosol particles of various sizes from aqueous solutions of salt. The technique was tested with sodium chloride, lithium carbonate and uranyl acetate at various aqueous concentrations which produced particles in the size range of 0.13-1.37 microm Mass Median Diameter (MMD). The generated aerosols were acceptably monodisperse with a geometric standard deviation of 1.4-2. Both MMD and Mass Median Aerodynamic Diameter (MMAD) increased significantly (p<0.001) with increased concentration of the salt in solution. The technique can also be used to generate aerosols of different chemical species. The results obtained indicate that the system is convenient for use with various aerosol-forming materials, with a stable particle size distribution being maintained for a long period of steady operation. The technique was successfully applied in wind tunnel studies to simulate the release of submicron radioactive particles and their interception by crops, grass and tree canopies. The relevance and application of the technique in other areas of environmental assessment studies is discussed.     

COMPARISON OF TWO AUTOREGRESSIVE MODELS FOR MONTHLY STREAM FLOW GENERATION1

ABSTRACT: Two autoregressive models for monthly stream flow generation are compared based on the reproduction of the historical record in terms of several important statistics such as the mean, standard deviation, skewness coefficient, correlation coefficient, and the reservoir storage components. In the comparison, both theoretical considerations and practical applications are employed to evaluate the performance of each model.     

A SIMPLE HYDRAULIC SIMULATOR1

ABSTRACT: A simple simulator was constructed, calibrated, programmed and used in management studies of a hydraulic system containing two pumping stations in series, connected by canals and reservoirs. The features of the model, its calibration and use are described, and comparisons between measured and computed hydraulic behavior are presented.     

Development of the Spatial Rainfall Generator (SRGEN) for the Agricultural Policy/Environmental Extender Model

Accurate spatial representation of climatic patterns is often a challenge in modeling biophysical processes at the watershed scale, especially where the representation of a spatial gradient in rainfall is not sufficiently captured by the number of weather stations. The spatial rainfall generator (SRGEN) is developed as an extension of the “weather generator” (WXGEN), a component of the Agricultural Policy/Environmental eXtender (APEX) model. SRGEN generates spatially distributed daily rainfall using monthly weather statistics available at multiple locations in a watershed. The spatial rainfall generator as incorporated in APEX is tested on the Cowhouse watershed (1,178 km²) in central Texas. The watershed presented a significant spatial rainfall gradient of 2.9 mm/km in the lateral (north‐south) directions based on four rainfall gages. A comparative analysis between SRGEN and WXGEN indicates that SRGEN performs well (PBIAS = 2.40%). Good results were obtained from APEX for streamflow (NSE = 0.99, PBIAS = 8.34%) and NO₃‐N and soluble P loads (PBIAS ≈ 6.00% for each, respectively). However, APEX underpredicted sediment yield and organic N and P loads (PBIAS: 24.75‐27.90%) with SRGEN, although its uncertainty in output was lower than WXGEN results (PBIAS: ?13.02 to ?46.13%). The overall improvement achieved in rainfall generation by SRGEN is demonstrated to be effective in the improving model performance on flow and water quality output.     

660MW超超临界燃煤机组袋式除尘器的设计

简介了660MW超超临界燃煤机组袋式除尘器的技术性能参数;阐述了袋式除尘器的设计方案及系统组成,以及除尘器除尘室间的气流分配、除尘室内的气流分布以及气流分布合理的重要性;引用运行数据说明除尘器工艺参数、结构参数、气流分配及气流分布设计的合理性.     

一种新型节能臭氧发生器

文章介绍了一种能耗低、效率高、快速生产臭氧的新装置。文中对该装置的工作原理、臭氧的生产过程、影响臭氧产率的因素以及该装置的特点等进行了简要介绍。     

诱导喷嘴改进滤筒脉冲清灰效果的实验研究

改善清灰效果是提高滤筒除尘效率的关键和难点问题。运用自制脉冲喷吹实验台,采用诱导喷嘴(超音速引流喷嘴和气流散射器)对325 mm×660 mm滤筒进行脉冲喷吹清灰实验研究,并与采用普通喷吹孔的实验结果进行比较分析,得出采用诱导喷嘴时侧壁正压力峰值平均值是普通喷吹孔的1.465倍;且采用诱导喷嘴时各测点的不均衡系数为0.768～1.336,普通喷口为0.270～2.251,而不均衡系数越接近于1,其清灰效果越好;同时,采用诱导喷嘴时各测点基本在同一时刻达到正峰值。实验充分表明采用诱导喷嘴确保了滤筒长度方向上内壁清灰压力的均匀性,且对滤筒清灰效果有明显的改善作用。     

袋式除尘器进气均布板结构参数对气流分布的影响分析

针对袋式除尘器的进气均布板主要结构参数对气流分布影响的问题,采用正交试验方法进行CFD模拟试验设计,并以气流速度相对均方根σ值作为气流均匀性的评价指标。研究结果给出了σ与板数n、板长L、挡板上端距灰斗顶部截面高度ΔH、挡板前后偏角θ及过滤风速v之间的函数关系式。表明适当增加n、增大ΔH和θ、减小L、降低v,可以提高进气流分布均匀程度,影响进气均匀分布程度的排序为L>θ>n>ΔH>ΔL。