落条式脱挥发物设备液体分布装置的研究

以糖浆为实验介质，采用接液法和电导探针法，研究了落条式脱挥发物设备中的列管式蒸发器用液体分布装置。该装置由一倒置的圆锥形分布器和一成膜器组成。前者用以实施管间的流体流量分布，后者用以实施管内流体的液膜分布。成膜器的最佳环隙宽为１．９～２．５ｍｍ，相应的底圆直径约为４６ｍｍ。分布的结构参数与进料流量、流体物性之间的关联式为Ｈ＝０．０３９ＱηＬ／ρｂ＾３（ｂ＋ｄ１）－０．１１８。

液体聚丁二烯橡胶的脱挥工艺

将质量分数为10.00%的聚丁二烯橡胶溶液水洗至中性后加热,加热后的胶液经预热器、浓缩器顶部分配盘分配后进入落条式脱挥器的列管中,聚丁二烯橡胶溶液在下落过程中经落条式脱挥器进一步浓缩至质量分数大于25.00%。研究了胶液浓度、进料速度、预热温度、落条式脱挥器的温度及压力等工艺条件,结果表明,落条式脱挥器脱挥工艺适用于液体聚丁二烯橡胶溶液的脱除溶剂,所得产品的微观结构含量与国外同类产品基本相当。

屏内面粗糙度与荧光粉涂敷工艺的关系

在彩管涂屏生产中很少遇到与玻壳设计参数有关的工艺不良问题。本文在工艺不良对策中提出了屏内面粗糙度对荧光粉涂敷过程有影响的观点 ,并进行了深入分析 。

涂屏64／74cmPFAK材改造SC工艺优化及不良分析对策

本文主要讲述了D线涂屏在64／74cmPFAK材改造过程中，为了解决生产中出现的条落及混色等问题，所进行的原因分析及采取的相应对策措施。

Fully Nonlinear Simulation for Fluid/Structure Impact：A Review

This paper presents a review of the work on fluid/structure impact based on inviscid and imcompressible liquid and irrotational flow. The focus is on the velocity potential theory together with boundary element method （BEM）. Fully nonlinear boundary conditions are imposed on the unknown free surface and the wetted surface of the moving body. The review includes （1） vertical and oblique water entry of a body at constant or a prescribed varying speed, as well as free fall motion, （2） liquid droplets or column impact as well as wave impact on a body, （3） similarity solution of an expanding body. It covers two dimensional （2D）, axisymmetric and three dimensional （3D） cases. Key techniques used in the numerical simulation are outlined, including mesh generation on the multivalued free surface, the stretched coordinate system for expanding domain, the auxiliary function method for decoupling the mutual dependence of the pressure and the body motion, and treatment for the jet or the thin liquid film developed during impact.

The Determination of Geographical Origin of Foodstuffs by Using Innovative Biological Bar-Code

Abstract： One of the great concerns of the customers is the traceability of the products. The authors proposed to link microbial ecology to geographical origin of foodstuffs by a molecular technique joined to an image analysis. Molecular techniques employing 16S and 28S rDNA profiles generated by PCR-DGGE were used to detect the variation in microbial community （bacteria, fungi） of Pangasius fish from Viet Nam harvested in different aquaculture farms and during different seasons and Shea tree fruits from five different districts in Mali. The bacterial DNA profiles from Pangasius fish and the fungal DNA profile from Shea tree fruits were specific to each place of production and could be used as a biological bar code certifying the origin of fish and fruit. To follow the product during processing, the authors proposed to identify and validate some pertinent biological markers which come from the environment of the food to assure their traceability during international trade. It is new analytical method which permits to determine the origin of food or to follow them during international trade.

The Impact of Atmospheric Deposition of Cadmium on Dominant Algal Species in the East China Sea

Cadmium(Cd) mainly derived from anthropogenic emissions can be transported through atmospheric pathway to marine ecosystem,affecting the phytoplankton community and primary productivity.In this study,we identified the toxicity threshold of Cd for phytoplankton under seawater conditions of the coastal East China Sea(ECS) through both laboratory and in situ mesocosm incubation experiments.The mesocosm experiment showed that Cd in low concentration(0.003 μg per μg chl a) was conducive to the growth of natural community and increased chl a productivity.In high concentration(0.03 μg per μg chl a) Cd acted as an inhibiting factor which decreased the total chl a productivity.The diatom community was found to be more sensitive to Cd toxicity than dinoflagellate,as the low concentration Cd showed toxicity to diatom but enhanced dinoflagellate growth.We noticed that the soluble Cd estimated from atmosphere deposition to the coastal ECS was below the toxicity threshold and the Cd deposition might promote phytoplankton growth in this region.In our laboratory experiments,adding Cd,similar to aerosol deposition,stimulated the growth of both dominant algal species Prorocentrum donghaiense Lu(dinoflagellate) and Skeletonema costatum(diatom).Adding Cd on a higher level inhibited the growth of both the species,but Skeletonema costatum seemed obviously more sensitive to toxicity.This indicates the potential impact of atmospheric deposition Cd on phytoplankton community succession in the ECS.

Nonholonomic motion planning for a free-falling cat using spline approximation

An optimal motion planning of a free-falling cat based on the spline approximation is investigated.Nonholonomicity arises in a free-falling cat subjected to nonintegrable velocity constraints or nonintegrable conservation laws.The equation of dynamics of a free-falling cat is obtained by using the model of two symmetric rigid bodies.The control of the system can be converted to the motion planning problem for a driftless system.A cost function is used to incorporate the final errors and control energy.The motion planning is to determine control inputs to minimize the cost function and is formulated as an infinite dimensional optimal control problem.By using the control parameterization,the infinite dimensional optimal control problem can be transformed to a finite dimensional one.The particle swarm optimization(PSO) algorithm with the cubic spline approximation is proposed to solve the finite dimension optimal control problem.The cubic spline approximation is introduced to realize the control parameterization.The resulting controls are smooth and the initial and terminal values of the control inputs are zeros,so they can be easily generated by experiment.Simulations are also performed for the nonholonomic motion planning of a free-falling cat.Simulated experimental results show that the proposed algorithm is more effective than the Newtoian algorithm.

Cover Crop and Irrigation Effects on Soil Microbial Communities and Enzymes in Semiarid Agroecosystems of the Central Great Plains of North America

Cover crops can have beneficial effects on soil microbiology by increasing carbon （C） supply, but these beneficial effects can be modulated by precipitation conditions. The objective of this study was to compare a fallow-winter wheat （Triticum aestivum L.） rotation to several cover crop-winter wheat rotations under rainfed and irrigated conditions in the semiarid US High Plains. Experiments were carried out at two sites, Sidney in Nebraska, and Akron in Colorado, USA, with three times of soil sampling in 2012--2013 at cover crop termination, wheat planting, and wheat maturity. The experiments included four single-species cover crops, a 10-species mixture, and a fallow treatment. The variables measured were soil C and nitrogen （N）, soil community structure by fatty acid methyl ester （FAME） profiles, and soil β-glucosidase,β-glucosaminidase, and phosphodiesterase activities. The fallow treatment, devoid of living plants, reduced the concentrations of most FAMEs at cover crop termination. The total FAME concentration was correlated with cover crop biomass （R = 0.62 at Sidney and 0.44 at Akron）. By the time of wheat planting, there was a beneficial effect of irrigation, which caused an increase in myeorrhizal and protozoan markers. At wheat maturity, the cover crop and irrigation effects on soil FAMEs had subsided, but irrigation had a positive effect on the β-glucosidase and phosphodiesterase activities at Akron, which was the drier of the two sites. Cover crops and irrigation were slow to impact soil C concentration. Our results show that cover crops had a short-lived effect on soil microbial communities in semiarid wheat-based rotations and irrigation could enhance soil enzyme activity. In the semiarid environment, longer time spans may have been needed to see beneficial effects of cover crops on soil microbial community structure, soil enzyme activities, and soil C sequestration.

Recovery of Collembola in Pinus tabulaeformis Plantations

Large areas of forest plantations have been developed in China. It is important to evaluate the soil fauna in plantations and the conditions needed for their recovery in view of the large areas of plantations in China. Three Pinus tabulaeformis forests, a 26-year-old plantation （P26） and a 45-year-old plantation （P45）, exposed to clear-cutting before plantation, and an 80 260-year-old natural forest （N260）, were chosen to study the effects of different forest ages/types on Collembola community in the lifter and soil layers during 2008 and 2009. Soil conditions in P26 and P45 were significantly deteriorated when compared to N260. A higher value of soil bulk density and lower values of soil organic matter, soil N, litter depth, soil pH, and soil water content were observed in P26 and P45. Totally, the same genera of Collembola tended to occur in the forests of all ages studied; however, the Collembola community structure was significantly impacted by the differences in forest age. Both in the litter and soil layers, the density and generic richness of the Collembola were the highest in N260 and the lowest in P26. Some collembolan groups were sensitive to soil conditions in particular forest ages. N260 was associated with relatively high abundance of Plutomus collembolans and P45 with relatively high abundance of Pseudofolsomia collembolans. The canonical correspondence analysis showed that the community structure of Collembola was mainly affected by forest age in both litter and soil layer. The ordination analysis of non-metric multidimensional scaling also found that the Collembola community did not recover to the level of natural forests in 26-year regeneration after clear-cutting. Even in 45-year regeneration after clear-cutting, the Collembola community only showed a slight recovery to the level of natural forests. Our results clearly showed that both Collembola community and soil conditions did not recover in 26- and 45-year regeneration after clear-cutting in P. tabulaeforrnis plantations; however, they might have the potential to recover in the future because the same genera of Collembola were distributed in the plantations and natural forests.