Catalytic oxidation of naphthalene using a Pt/Al2O3 catalyst

Polycylic aromatic hydrocarbons (PAHs) are listed as carcinogenic and mutagenic priority pollutants, belonging to the environmental endocrine disrupters. Most PAHs in the environment stem from the atmospheric deposition and diesel emission. Consequently, the elimination of PAHs in the off-gases is one of the priority and emerging challenges. Catalytic oxidation has been widely used in the destruction of organic compounds due to its high efficiency (or conversion of reactants), its economic benefits and good applicability.

This study investigates the application of the catalytic oxidation using Pt/γ-Al₂O₃ catalysts to decompose PAHs and taking naphthalene (the simplest and least toxic PAH) as a target compound. It studies the relationships between conversion, operating parameters and relevant factors such as treatment temperatures, catalyst sizes and space velocities. Also, a related reaction kinetic expression is proposed to provide a simplified expression of the relevant kinetic parameters.

The results indicate that the Pt/γ-Al₂O₃ catalyst used accelerates the reaction rate of the decomposition of naphthalene and decreases the reaction temperature. A high conversion (over 95%) can be achieved at a moderate reaction temperature of 480 K and space velocity below 35,000 h⁻¹. Non-catalytic (thermal) oxidation achieves the same conversion at a temperature beyond 1000 K. The results also indicate that Rideal–Eley mechanism and Arrhenius equation can be reasonably applied to describe the data by using the pseudo-first-order reaction kinetic equation with activation energy of 149.97 kJ/mol and frequency factor equal to 3.26 × 10¹⁷ s⁻¹.     

桉木硫酸盐浆不同漂白技术的评价

高白度漂白商品浆的白度已从通常的88%～90%提高到更高的水平,达到92%.这种高白度的要求导致了纸厂使用高价格光学漂白剂,以及过量使用这种添加剂的环境风险.     

Effect of Thickness of the p-AlGaN Electron Blocking Layer on the Improvement of ESD Characteristics in GaN-Based LEDs

The following letter presents a study regarding GaN-based light-emitting diodes (LEDs) with p-type AlGaN electron blocking layers (EBLs) of different thicknesses. The study revealed that the LEDs could endure higher electrostatic discharge (ESD) levels as the thickness of the AlGaN EBL increased. The observed improvement in the ESD endurance ability could be attributed to the fact that the thickened p-AlGaN EBL may partly fill the dislocation-related pits that occur on the surface of the InGaN-GaN multiple-quantum well (MQW) and that are due to the strain and the low-temperature-growth process. If these dislocation-related pits are not partly suppressed, they will eventually result in numerous surface pits associated with threading dislocations that intersect the InGaN-GaN (MQW), thereby reducing the ESD endurance ability. The results of the experiment show that the ESD endurance voltages could increase from 1500 to 6000 V when the thickness of the p-AlGaN EBL in the GaN LEDs is increased from 32.5 to 130 nm, while the forward voltages and light output powers remained almost the same.     

烧结成品运输自动控制系统的改进

对烧结成品运输自控系统不稳定性因素进行了分析，提出了采取优化硬件外围工作环境，完善软件保护程序等改进措施。改进后的自控系统稳定性明显提高。     

Effect of deformation route on microstructural development in aluminum processed by equal channel angular extrusion

Aluminum has been deformed by equal channel angular extrusion (ECAE) to obtain submicron-grained structures under different deformation routes. The deformation routes were varied by rotating billets through 0, 90, and 180 deg between each extrusion pass, and were designated as route A, B_C, and C, respectively. Based on quantitative microstructural analysis, the effectiveness of the deformation route is shown to depend upon the different definition used. The order of effectiveness is (a) A > B_C > C for both 90 and 120 deg dies, in terms of the generation of high-angle grain boundaries (HAGBs); (b) B_C > C > A for both 90 and 120 deg dies, in terms of the formation of equiaxed shape of grains; and (c) B_C > A > C for 90 deg die and B_C ∼ A > C for 120 die, in terms of reducing grain size. It is suggested that the generation of HAGBs can be related to the accumulation of nonredundant strain, while the shape and orientation of grains may be linked to the shearing patterns of the deformation route.     

Approach for Overcoming Numerical Inaccuracy Caused by Load Discontinuity

It was found that the discontinuity at the end of an impulse will lead to numerical inaccuracy as this discontinuity will result in an extra impulse and thus an extra displacement in the time history analysis. In addition, this extra impulse is proportional to the discontinuity value at the end of the impulse and the size of integration time step. To overcome this difficulty, an effective approach is proposed to reduce the extra impulse and hence the extra displacement. In fact, the novel approach proposed in this paper is to perform a single small time step immediately upon the termination of applied impulse, whereas other time steps can be conducted by using the step size determined from accuracy consideration in period. The feasibility of this approach is analytically explored. Further, analytical results are confirmed by numerical examples. Numerical studies also show that this approach can be applied to other step-by-step integration methods. It seems that to slightly complicate the programming of dynamic analysis codes is the only disadvantage of this approach.     

Applying CIM technology to image factories

Image processing allows the automation of the business transaction, turning “paper factories” into “image factories.” This burgeoning new area of computerization needs new paradigms, theories, and methods to maximize its effectiveness at cutting time and costs. This paper investigates what this new area of computerization can gain from CIM technology. It examines the similarities between the processing of computer images in a paperless business environment and the processing of materials into products in the manufacturing plant. These similarities will allow us to apply mature, well-tested CIM techniques to emerging image factories.     

Ozonation of CI Reactive Black 5 using rotating packed bed and stirred tank reactor

This study investigates the ozonation of CI Reactive Black 5 (RB5) by using the rotating packed bed (RPB) and completely stirred tank reactor (CSTR) as ozone contactors. The RPB, which provides high gravitational force by adjusting the rotational speed, was employed as a novel ozone contactor. The same ozone dosage was separately introduced into either the RPB or the CSTR for the investigation, while the experimental solution was continuously circulated within the apparatus consisting of the RPB and CSTR. The decolorization and mineralization efficiencies of RB5 in the course of ozonation are compared for these two methods. Moreover, the dissolved and off‐gas ozone concentrations were simultaneously monitored for the further analysis. As a result, the ozone mass transfer rate per unit volume of the RPB was significantly higher because of its higher mass transfer coefficient and gas–liquid concentration driving force. Furthermore, ozonation kinetics was found to be independent of the gravitational magnitude of an ozone gas–liquid contactor. Therefore, the results suggest employing RPBs as ozone‐contacting devices with the advantage of volume reduction. The experimental results, which can be used for further modeling of the ozonation process in the RPB, also show the requirement of correct design for the RPB. Consequently, the present study is useful for the understanding of practical application of RPBs. Copyright © 2004 Society of Chemical Industry     

Designing better adaptive sampling algorithms for ECG Holtersystems

Let Ψ be any adaptive sampling algorithm that can run in real time on a tapeless multichannel electrocardiogram (ECG) Holter system. Simple methods which can significantly improve Ψ's fidelity are described and their results are compared in this paper. It is shown that by adding some simple tests to Ψ, the signals reconstructed by Ψ can be improved as much as 5.45 dB. It is also shown that under the same data rate, a good data compressor with slowly sampled input ECG is preferable to a bad data compressor with highly sampled input ECG