EPA焦炉大气污染物排放标准的技术思想解读

对美国国家环保署制定的美国焦炉大气污染物排放标准的提出背景、制定原则和内容要点等作了简要阐述,并建议借鉴标准所包含的某些技术思想,如：以先进技术推动＂源头治理＂、污染物排放标准限值应随技术进步而日趋严格等理念,以完善我国的焦炉环保法规。     

发射光谱法同时测定纯铂中21个杂质元素

本文结合国内外各分析方法的长处，对纯铂中杂质元素的测定进行了研究，采用粉末试样直流电弧激发摄谱，同时测定了纯铂中的21个杂质元素，各元素测定的相对标准偏差≤25％，方法简便，适用范围广，可用于99．9％－99．995％Pt中杂质元素的分析。     

NEURAL NETWORK-BASED MODELING AND OPTIMIZATION FOR EFFECTIVE VEHICLE EMISSION TESTING AND ENGINE CALIBRATION

In automotive manufacturing, vehicle emission testing and engine calibration are the key to achieving emission standards with satisfactory fuel economy. Because of the complexity of physical and chemical phenomena occurring during engine combustion and catalytic conversion and the lack of real-time measurements of key process and performance parameters, engine calibration and emission testing are still experiment-assisted trial-and-error practices, which are always expensive and inefficient. In this article, a neural network (NN)-based modeling approach is introduced to characterize engine and catalytic converter operations. A model-based optimization method is also introduced to identify optimal engine calibration parameters so that emission reduction and fuel efficiency improvement can be achieved simultaneously. This development facilitates a comprehensive performance analysis of engine and catalytic converters with much less effort required for experiments.     

Effects of operational parameters on emission performance and combustion efficiency in small-scale CFBCs

A well-designed CFBC can burn coal with high efficiency and within acceptable levels of gaseous emissions. In this theoretical study effects of operational parameters on combustion efficiency and the pollutants emitted have been estimated using a developed dynamic 2D (two-dimensional) model for CFBCs. Model simulations have been carried out to examine the effect of different operational parameters such as excess air and gas inlet pressure and coal particle size on bed temperature, the overall CO, NO_x and SO₂ emissions and combustion efficiency from a small-scale CFBC. It has been observed that increasing excess air ratio causes fluidized bed temperature decrease and CO emission increase. Coal particle size has more significant effect on CO emissions than the gas inlet pressure at the entrance to fluidized bed. Increasing excess air ratio leads to decreasing SO₂ and NO_x emissions. The gas inlet pressure at the entrance to fluidized bed has a more significant effect on NO_x emission than the coal particle size. Increasing excess air causes decreasing combustion efficiency. The gas inlet pressure has more pronounced effect on combustion efficiency than the coal particle size, particularly at higher excess air ratios. The developed model is also validated in terms of combustion efficiency with experimental literature data obtained from 300 kW laboratory scale test unit. The present theoretical study also confirms that CFB combustion allows clean and efficient combustion of coal.     

Present Situation of Purification Technologies for Automotive Exhaust in China

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油电混合动力工程机械研究现状及发展趋势

随着全球化石能源的日益枯竭和环境污染的日益严重,如何改善工程机械的排放质量和实现工程机械的节能已经引起工程机械生产厂家和用户的广泛关注。油电混合动力技术近年来已经成为工程机械节能降耗的一个重要研究方向,受到工程机械领域的高度重视。根据研究工作积累和文献资料调研,总结了国内外主要研究机构对于油电混合动力工程机械的研究现状,分析了油电混合动力工程机械研制需要解决的关键技术,对油电混合动力工程机械的发展趋势进行了预测。     

Characterization system based on image mapping for field emission devices

Field Emission devices (FE) have been proposed as efficient electron sources for several applications such as electron microscopy and vacuum sensors. Evidently, characterization methods applied during development phase of FE devices are crucial to evaluate aspects related with their working stability, homogeneity, and efficiency. However, the traditional methods provide only overall information about such characteristics, which difficult to improve the performance of these devices and their integration with electronics. To overcome this problem, this work presents an alternative system to characterize FE devices through electron emission imaging in real-time. The proposed system acquires I-V features of FE devices, while a video camera captures the emission image from a phosphor screen. Virtual instrumentation based on LabVIEW manages the whole system including measurement instruments, image capture, and data processing. As a result, histograms, 3D maps, and other FE analyses provide information about emitting characteristics of selected regions of interest. The main contribution of this work is to offer an important tool for the analyses of electron emission, by the association of captured images with the localized emission current. The extracted information from our system can efficiently support the characterization and the development of FE devices.     

耐火材料声发射源信号的盲反卷恢复

声发射信号是表征材料内部损伤状态的重要指标。由于源信号无法直接获取,研究的通常是传播一段距离后已失真的信号,这对材料损伤状态的准确判断带来了影响。为了降低传播路径对声发射源信号的衰减和失真带来的不利影响,假设声发射信号在耐火材料的传递路径为线性系统,对传递通道的冲击响应函数进行了估计,并设计了反卷滤波器。与实验结果对比发现,该方法很好的辨识了传递通道未知的系统,并能一定程度地恢复声发射源信号,为材料损伤状态的准确判断提供参考。     

浅谈电解铝厂规模电解槽容量与环境保护

本文对国内现行电解铝工业污染物排放标准提出了修改意见；阐述了电解铝厂生产规模、电解槽容量、污染物生成量。以及电解烟气净化回收与环境保护之间的关系；电解槽集气效率的计算方法；提高槽集气效率的措施以及强化环境保护。加强管理等若干问题。     

Modeling of Filling and Solidification Process for TiAl Exhaust Valves During Suction Casting

Investment and suction casting (ISC) represents an economic and promising process route to fabricate automotive exhaust valves of γ-TiAl based alloys, but information available on the metal flow and the temperature changes during mould filling and solidification process for the ISC process is meager. A sequentially coupled mathematical flow-thermal model, based on the commercial finite-volume/finite-difference code FLOW-3D and the finite-element code PROCAST, has been developed to investigate the ISC process. In term of calculating the flow and temperature fields during the filling and solidification stages, potential defects including the gas bubbles and the surface air entrainment occurred in the mould filling process and the shrinkage porosities formed in the solidification process are predicted and the reasons for the formation of these defects are also analyzed. The effects of filling pressure difference control methods and moulds on gas bubble and surface air entrainment behavior are presented. It is found that by changing the filling pressure difference control methods from general suction casting to "air leakage" suction casting and reducing air leakage flow rates, the gas bubbles are eliminated effectively, and the surface air entrainment attenuate dramatically. With resort to a mould with a tetragonal runner, the surface air entrainment decrease to the lowest level. Finally, the water analogue and suction casting experiments of exhaust valves are implemented for further validation of the simulation results.