Modeling of photocatalytic oxidation of VOCs in a packed bed reactor under continuous and discontinuous illuminations

In this paper, a mathematical model is presented to describe the photocatalytic degradation of VOCs in a packed bed reactor. Here, the adsorption of VOCs on the wall of the reactor is taken into account and the diffusion of VOCs in the axial direction is neglected. First-order kinetics is used to describe the photocatalytic oxidation of VOCs. The analytical solution of the present model is obtained by traveling wave method. The solution shows that the reactor performance is totally dependent on the inlet concentration of VOCs when the time is large enough. The present model is validated through the experimental result of the photocatalytic oxidation of trichloroethylene in a packed bed and the predicted results accord well with the experimental data. The influence of flow rate and inlet concentration on the performance of the reactor is discussed in detail. High flow rate offers high reaction rate and low conversion efficiency. The different inlet conditions and different reaction patterns are also investigated. The model would be useful to estimate the rate constant and help to the design of the reactor.     

数据加密技术在计算机安全中的应用

随着计算机网络技术的不断发展,计算机互联网在人们的生活中应用越来越广泛,网络安全问题也随之而来。目前的计算机安全存在着诸多因素的威胁,研究人员也在致力于这方面的研究与发展,应用先进的技术来保证计算机安全,为计算机用户的信息安全提供更高的保障。本文将针对计算机安全问题进行分析,探讨数据加密技术在计算机安全中的应用。     

A novel and versatile method for the synthesis of soluble fullerenated polymers

Summary A new route for the preparation of soluble fullerenated polymer through the reaction of carbanion intermediates of polymers with fullerenes, particularly C₆₀, is demonstrated. Confirmation of the covalent attachment of C₆₀ to the polystyrene backbone is by a variety of techniques such as UV-Vis, FT-IR, TGA, SEM and ¹³C NMR etc. The product, which has a visibly brownish yellow cast when compared with the unreacted polymer, is soluble in some common organic solvents. The thermal stability of pure polystyrene is enhanced by C₆₀-chemical modification, and no bonds within the carbon sphere are broken.     

Surface activity and solubilization of a novel series of functional polyurethane surfactants

Functional polyurethane surfactants (di‐block and tri‐block) were synthesized by addition polymerization of 2,4‐toluenediisocyanate with poly(propylene oxide) and monoallyl‐end‐capped poly(ethylene oxide). The chemical structure of the polyurethane surfactants was confirmed by Fourier transform infrared and ¹H NMR spectroscopy. These polymeric surfactants were found to have excellent surface activity. The lowest surface tension of polyurethane surfactant aqueous solutions could be reduced to 37.6 mN m^?1. All the polyurethane surfactants synthesized had low critical micelle concentrations and could reduce the surface tension even at very low concentration levels (10^?6–10^?5 mol L^?1). The solubilization of toluene in micelles of the synthesized polyurethane surfactants was studied using UV‐visible spectroscopy, and the results showed that they all exhibited good solubilization capacity. Possible solubilization positions of toluene in the micelles are conjectured. Copyright © 2006 Society of Chemical Industry     

基于Creator的战场地形仿真研究

如何解决地形模型精细度、逼真度与仿真速度之间的矛盾是军事仿真的难点问题。本文研究了三维地形生成的关键技术,并详细阐述了利用MultiGen Creator建模工具,采用DEM数据和卫星遥感影像数据构建和优化大面积战场地形的原理和方法,最后结合实例生成战场地形。仿真结果表明,该方法生成的模型达到了精细度高、真实感强、实时性好等仿真要求。     

Effects of a strong polyelectrolyte on the rheological properties of concentrated cementitious suspensions

Strong polyelectrolytes, referred to as superplasticizers, are known to improve the initial fluidity of concentrated cement suspensions. To quantify how the polyelectrolytes affect the fluidity, we have studied the effect of a strong anionic polyelectrolyte, melamine formaldehyde sulfonate (MFS), on the zeta potential of cement particles and on the steady-shear and low-amplitude rheological properties of cement suspensions. Adsorption of low concentrations of MFS onto the cement particles leads to an inversion in the sign of the surface potential, causing the electrostatically flocculated particles to become electrostatically dispersed and giving rise to a corresponding decrease in the steady-shear viscosity and storage modulus. At an intermediate MFS concentration, the steady-shear viscosity and the storage modulus each display a minimum. This concentration corresponds to that at which the zeta potential becomes constant. Larger concentrations of MFS result in an increase in the viscosity and storage modulus, which is attributed to depletion flocculation. These results thus relate the interaction between particles to the suspension fluidity through the analysis on the surface potential of particles and microstructure of suspension.     

Generic Adaptive Sliding Mode Control for a Quadrotor UAV System Subject to Severe Parametric Uncertainties and Fully Unknown External Disturbance

International Journal of Control, Automation and Systems - This paper aims to provide a generic robust controller that is able to manipulate all kinds of quadrotor unmanned aerial vehicle (UAV)...     

Sensor Fault Diagnosis and Unknown Disturbances Estimation of High Switching Frequency Single-phase PWM Rectifier

International Journal of Control, Automation and Systems - The fault and disturbances estimation has an important role in the modern traction railway system. This paper proposes a unique method for...     

基于深度学习的小样本声目标识别方法

声目标分类识别是声源识别领域的核心问题,然而,在应用深层神经网络进行声目标分类识别时,从少量样本中学习(样本复杂度较低)是一个具有挑战性的问题;针对此问题,提出了一种基于深度学习的小样本声目标识别方法,该方法将手工设计特征和对数梅尔声谱特征结合到一起,扩充了深度学习模型的可利用特征量,提高了声信号识别效率和精度;在实验验证中,该方法在测试集上实现了87.6%的识别精度;更进一步地,用较少量的训练样本对该方法和其它几种主流的深度学习模型的性能进行了比较验证,结果表明,该方法只需要更少量的数据即可实现同样的识别精度,在声源探测领域具有一定应用价值。