A finite model for the prediction of the UV radiation field around a linear lamp

A finite model was established to predict the radiation field around a line lamp treating contaminated air, taking into account the effects of the radius of the lamp and sleeve, as well as other physical parameters. Both irradiance and fluence rate could be calculated, and the model was validated with measured data and by comparison with a conventional extense source volumetric emission (ESVE) model. Diffuse and specular emissions for a line lamp were compared, showing that diffuse emission is more appropriate for a low pressure mercury UV lamp. Refraction by the lamp sleeve can induce a 12% increase in fluence rate near the sleeve, while reflection causes a 7% decrease. When the attenuation coefficient of a gaseous chemical is less than 0.04 m^?1 the error due to ignoring its light absorption is less than 1%, within a distance of 0.2 m from the lamp.     

A study on the newtonian fluid flow past a sphere in a tube

Newtonian flow past a sphere in a tube of finite radius was investigated experimentally and numerically. The flow visualization technique using He-Ne laser as a light source has been employed to study the vortex characteristics occurring on the backside of the sphere which is set stationary inside the tube moving vertically. It has been revealed that the vortex size decreases as the ratio of sphere to tube diameter (a) increases. Galerkin finite element simulation was able to predict those phenomena almost exactly and also used to calculate the drag coefficients which vary with the Reynolds number anda.     

Development of a Versatile Aerosol Generation System for Use in a Large Wind Tunnel

A novel aerosol generation system has been constructed for use in a large wind tunnel for two distinct research projects. One project requires a uniform aerosol concentration over the wind tunnel cross section, while the other project demands a stratified aerosol concentration distribution. The system consists of an array of venturi nozzles, which entrains particulate matter from a moving conveyor belt and disperses it into the tunnel under the force provided by a compressed air source. For the stratified release configuration, only the bottom row of nozzles was used and a confinement sleeve was installed to prevent mixing with clean air; the mixing fans were omitted from this configuration. The uniform release arrangement was tested by gravimetrically measuring particle concentration over the cross section of the tunnel for tunnel speeds of 0.1 and 1.0 m/s; uniformity was achieved within a coefficient of variation of 6.4%. The stratified distribution results show a high concentration near the floor, which diminishes with increased height. Particle size distribution was also determined on filter samples using scanning electron microscopy analysis for the uniform release experiments. No appreciable difference in mass median diameter or geometric standard deviation could be discerned for the various sampling points.     

Factors That Affect Diffuse Reflection Performance of Microcellular Foamed Plastics

The structure of microcellular foamed plastics causes optical, acoustic, and electrical properties. The diffuse reflection performance of microcellular foamed plastics can be applied as a high performance diffuse reflector. To improve microcellular foaming process, a simulation was conducted. It was to analyze the factor affecting when microcellular foamed plastics realized the diffuse reflection performance. Cell morphology of microcellular foamed plastics can be expressed through four factors. From result of simulation made a data base about cell morphology and diffuse reflectance. And the statistical method was used for identify contributions by factors.     

The heat and mass transfer from a fluid sphere at large reynolds and peclet number

Analytic expressions have been derived for the steady rate of heat or mass transfer from a fluid sphere in uniform motion at large Reynolds and Peclet number. The solution is applicable to cases where both phase resistances are of the same order of magnitude, or when the resistance of one phase is negligible. The analysis has shown that if finite values of fluid viscosity and density are considered the transfer rates are considerably less than those obtained from the ideal fluid model. The maximum flux for a fluid sphere occurs near the equatorial plane and in this respect its behavior differs significantly from a solid sphere.     

Dispersion of aqueous polymer solutions injected from a point source into turbulent water flows

The dispersion of water and aqueous polymer, when injected from a point source along the flow centre line into two-dimensional, fully developed and uniform turbulent flows with flow Reynolds numbers of the order of 4.6 × 10⁵, have been studied experimentally. Concentration profiles at five locations were obtained for injection concentrations and velocities in the ranges 0 to 1000 w.p.p.m. and equal to or less than the local flow velocity. The concentrations were assessed using a fluorescing dye technique. Empirical equations describing the radial and longitudinal concentration field as a function of the injection and flow parameter are given. A universal concentration profile, independent of the injection flow rate and concentration and length of injection source tube, and valid for water and for polymer solution, under both fully developed and uniform flow, is also presented. The results indicate that the turbulent dispersion of polymer solution is suppressed compared to that of water.     

利用有限元分析方法对旁路取风骤冷器的研究

水泥窑在处置固废过程中,尤其是处置含氯元素较高的固废时,氯元素容易在回转窑系统内循环富集并致系统结皮和堵塞,旁路放风系统是解决该问题的有效手段.取风骤冷器结构是旁路放风系统的关键部件.利用有限元分析对水泥窑旁路放风系统的取风骤冷器结构(直通式结构、直切式结构、旋转套筒式结构)分别进行速度分布、温度分布和压力分布进行研究...     

A suspension of spheres in a dilute polymer solution

The Hookean dumbbell model of a macromolecule predicts non‐uniform density and pressure fields surrounding a sphere buoyant in a dilute polymer solution when the size of the sphere is of the same order of magnitude as the size of the macromolecules. Using this prediction, the root mean square separation distance of a suspension of spheres buoyant within a dilute polymer solution is found to be inversely proportional to both the square of the radius of a sphere and the density of the polymer solution. The phase space distribution function for an ensemble of spheres immersed at equilibrium within a dilute polymer solution is found and used to define the magnitude of the ensemble average peculiar acceleration of the spheres. The peculiar acceleration results from changes in direction of the peculiar velocity. It is found to be directly proportional to the temperature, polymer density, and square of the radius of a sphere and inversely proportional to the mass of a sphere. The self‐ diffusivity of the particles varies directly with the square root of the temperature. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Effect of sleeve colour and background colour on change in colour assessments†

The two standard grey scales, ISO 105‐A02 and ISO 105‐A03, used for assessing change in colour and staining, respectively, are both typically provided mounted in black material and within a black sleeve. However, some grey scales are now provided mounted in grey material and within a grey sleeve. This paper reports psychophysical data and shows that the change in colour grades obtained from grey scales are not affected by the background colour of the viewing cabinet. A small, but statistically significant, effect is found for the colour of the sleeve with higher grades being found when using the black sleeve compared to when using the grey sleeve. However, when the samples being assessed are masked by a sleeve of the same colour as that used with the grey scale, an extensive field trial shows that the colour of the sleeve does not affect the change in colour grades obtained under commercial conditions.     

Surface reflectance estimation by the dichromatic model

A method is described for estimating the surface-spectral reflectances of glossy objects when the color signal is a mixture of diffuse reflections, specular reflections, and interreflections. The objects are inhomogeneous dielectric materials, and the reflected light is measured using a spectroradiometer. We first describe the main idea; the color signals, reflected from two closely apposed surfaces with a single interreflection between them, can be expressed by a linear combination of the illuminant spectrum and two diffuse spectral reflection functions. We introduce a representation in which each of these three terms is projected onto a point on a unit sphere. Estimation of the diffuse reflection functions is then reduced to finding the vertices of the spherical triangle. Next, an algorithm is described to estimate the locations of the vertices of diffuse reflectance functions from the measured samples. The reliability of the algorithm is demonstrated in an experiment using two plastic objects with glossy surfaces. © 1996 John Wiley & Sons, Inc.     

碳源类型和温度对BAF脱氮性能影响研究

以某钢铁厂的二级出水为研究对象,研究了曝气生物滤池(BAF)系统的挂膜,不同碳源类型和温度对该系统脱氮的影响。结果表明:利用含有硝化菌与好氧反硝化菌的富集菌液进行挂膜,16d基本完成挂膜,氨氮、硝态氮的去除率分别高达90.2%和92.2%。不同碳源类型对系统的脱氮性能影响存在差异,以葡萄糖和乙醇作为碳源时效果最佳,氨氮和硝态氮的去除率均超过85%,总无机氮去除率分别是93.4%、95.6%。乙酸钠为碳源时亚硝态氮的质量浓度积累最高达5.79mg/L,采用其它碳源时亚硝态氮几乎没有积累;当不投加外部碳源时,通过内源呼吸代谢作用进行硝化反硝化效果最差,总无机氮的去除率仅有20.4%。随着温度的上升,硝化和反硝化效果逐渐升高,其中硝化的最适温度是在27.3℃左右,氨氮的去除率高达91.1%,好氧反硝化过程对温度的耐受性比较好,在17.5～33.1℃时,平均去除率大于90%。     

Fabrication of Large Area Periodic Nanostructures Using Nanosphere Photolithography

Large area periodic nanostructures exhibit unique optical and electronic properties and have found many applications, such as photonic band-gap materials, high dense data storage, and photonic devices. We have developed a maskless photolithography method—Nanosphere Photolithography (NSP)—to produce a large area of uniform nanopatterns in the photoresist utilizing the silica micro-spheres to focus UV light. Here, we will extend the idea to fabricate metallic nanostructures using the NSP method. We produced large areas of periodic uniform nanohole array perforated in different metallic films, such as gold and aluminum. The diameters of these nanoholes are much smaller than the wavelength of UV light used and they are very uniformly distributed. The method introduced here inherently has both the advantages of photolithography and self-assembled methods. Besides, it also generates very uniform repetitive nanopatterns because the focused beam waist is almost unchanged with different sphere sizes.     

Improving the performance of a thermoelectric power system using a flat-plate heat pipe

A gravitational flat-plate heat pipe is designed and fabricated in this paper to serve as a heat spreader to diffuse the local heat source to the hot side of the thermoelectric power module. Based on this, an experimental test for the thermoelectric power generation system is conducted to study the influences of the heat spreader on the temperature uniformity and power generation performance when exposing to a local heat source. In addition, the effects of the heating power, inclination angle, and local heat source size on the power generation performance of the thermoelectric power module using a flat-plate heat pipe as a heat spreader are examined and compared with that using a metal plate. The results indicate that the gravitational flat-plate heat pipe has considerable advantages over the metal plate in the temperature uniformity. The superiority of temperature uniformity in the improvement of power generation performance for the thermoelectric power system using a heat pipe is demonstrated. Particularly, the heat pipe shows good adaptability to placement mode and the local heat source size, which is beneficial to the application in the thermoelectric power generation.     

A cylindrical photoreactor irradiated from the bottom—I. Radiation flux density generated by a tubular source and a parabolic reflector

The present work studies the radiant energy field generated by a system made up of an ultraviolet radiation source located at the focal axis of a cylindrical reflector of parabolic cross-section. This system allows us to irradiate a cylindrical photoreactor from the bottom, avoiding the introduction of the source in the reaction space.The equations governing the energy transfer were formulated and solved numerically; to do so, three emission models were applied: the line source model with emission in parallel planes, the line source model with spherical emission, and the extense source model with volumetric emission.The behaviour of each one of these models was comparatively analysed to establish their ability to predict the radiant energy flux density within the reacting space of the photoreactor.A very simple experimental check of the model predictions showed very good agreement only when compared with those of the extense source model with volumetric emission.     

Facile solvothermal synthesis of cube-like Ag@AgCl: a highly efficient visible light photocatalyst

In this paper, a stable and highly efficient plasmonic photocatalyst, Ag@AgCl, with cube-like morphology, has been successfully prepared via a simple hydrothermal method. Using methylene dichloride as chlorine source in the synthesis can efficiently control the morphology of Ag@AgCl, due to the low release rate of chloride ions. Scanning electron microscopy (SEM), X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and UV-vis diffuse reflectance spectra were used to characterize the obtained product. The photocatalytic activity of the obtained product was evaluated by the photodegradation of methyl orange (MO) under visible light irradiation, and it was found, interestingly, that Ag@AgCl exhibits high visible light photocatalytic activity and good stability.     

Color effect of light sources on peridot based on CIE1976 L*a*b* color system and round RGB diagram system

Previous research indicated that the peridot's color is dominated by the selective absorption of visible light caused by ferrous ion, the hue angle of which is in an inverse ratio of the concentration of Fe²⁺. This article focuses on the color effect of peridot under different standard light sources based on the CIE1976 L*a*b* color space system and round RGB diagram system and tries to find the best one for its grading and display. Based on the results of a series of experiments, including electron microprobe analysis, spectrophotometer, UV‐Vis spectrum, standard illumination box, and Munsell neutral color chips, it was suggested that the spectral power distribution and color temperature of a standard light source significantly influence the color of peridot in terms of lightness and chroma, particularly in the hue of peridot. As for color grading and displaying of peridot, standard light source A fails to fit in, and the color of peridot under a fluorescent light source has a higher chroma but a lower hue angle than that under daylight light source. The best choice for grading and displaying peridot is the standard light source D₆₅. It is better to distinguish the hue of peridot when it is calculated by the round RGB diagram system.     

Cationic microgel emulsion with a high solid content by a multistep addition method in inverse microemulsion polymerization

The multistep addition of a monomer and initiator was developed to successfully synthesize cationic polyacrylamide microgels with solid contents (SCs) greater than 35% and cationic monomer concentrations of 0–40 mol % by inverse microemulsion polymerization. Two feed methods, three‐step nonuniform addition and five‐step uniform addition, were implemented to obtain microgel emulsions with 37% SC. The former addition method was designed according to the solubilization limit of the microemulsion before step polymerization, and that of the latter was a constant based on the remaining surfactant weight in the reactor. The product properties in the intermediate processes of these two methods were compared by dynamic light scattering and viscosity measurement. The results show that the products here were translucent microemulsions instead of milky ones when they were synthesized by a semicontinuous polymerization. Also, the particle sizes of these two methods were almost the same; this indicated that the oscillation phenomenon in continuous polymerization at a high SC was avoided. With the former feed method, the risk and operation cost in the synthesis process could be cut down greatly. Moreover, the viscosity of the cationic microgel emulsion conformed to the Krieger–Dougherty equation with a greater value of intrinsic viscosity than that of a hard‐sphere system because of an electroviscous effect. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40585.     

近壁面静止圆球的尾迹特性

圆球在大空间均匀来流下的绕流特性已得到了广泛的研究,但是壁面对圆球绕流特性的影响还未清楚。通过实验方法研究了与壁面接触的静止圆球在明渠流中的绕流特性,重点关注了圆球后尾迹的特性。研究发现,圆球尾迹存在三种状态：稳定状态、非稳定对称状态和非稳定非对称状态。当Re<150时,尾迹呈稳定状态,尾迹关于垂直于壁面的平面对称;当150<Re<400时,尾迹呈对称状态,Reynolds数较高时,圆球后存在规则的、周期性的涡脱落,Strouhal 数为0.26~0.33,脱落涡关于垂直于壁面的平面对称,此时尾迹功率谱的频带分布较宽;而当Re>400时,圆球后的涡脱落不再对称,尾迹随着Reynolds数的增大呈现混沌特征。