快速煅烧分解石灰石对其吸收CO2和SO2的影响

在加热过程中,应用一种新型的快速加热装置——铂膜反应器,及时准确地获得样品质量和颗粒温度,来研究石灰石的煅烧分解,并对石灰石加热速率高达750℃/s下的分解反应特性,及其对分解后产生的氧化钙吸收CO2和脱硫的化学反应特性进行了研究.实验表明,在初始加热阶段,高升温速率明显阻碍了煅烧分解的进行,这对分解后的CaO吸收CO2的效果影响不大.当加热速率升高时,石灰石分解后产生的CaO吸收CO2和脱硫过程中,钙利用率显著下降.     

In situ metal ion contamination and the effects on proton exchange membrane fuel cell performance

Automotive fuel cell technology has made considerable progress, and hydrogen fuel cell vehicles are regarded as a possible long-term solution to reduce carbon dioxide emissions, reduce fossil fuel dependency and increase energy efficiency. Even though great strides have been made, durability is still an issue. One key challenge is controlling MEA contamination. Metal ion contamination within the membrane and the effects on fuel cell performance were investigated. Given the possible benefits of using stainless steel or aluminum for balance-of-plant components or bipolar plates, cations of Al, Fe, Ni and Cr were studied. Membranes were immersed in metal sulfide solutions of varying concentration and then assembled into fuel cell MEAs tested in situ. The ranking of the four transition metals tested in terms of the greatest reduction in fuel cell performance was: Al³⁺ ? Fe²⁺ > Ni²⁺, Cr³⁺. For iron-contaminated membranes, no change in cell performance was detected until the membrane conductivity loss was greater than approximately 15%.     

Catalytic reforming of natural gas for hydrogen production in a pilot fluidized-bed membrane reactor: Mapping of operating and feed conditions

A fluidized-bed membrane reformer was operated in two independent laboratories to map various operating conditions, to investigate the effects of changing the composition of the natural gas feed stream and to verify earlier experimental trials. Two feed natural gases were tested, containing either 95.5 or 90.1 mol% of methane (3.6 or 9.9 mol% of other gaseous higher hydrocarbons). Experimental tests investigated the influence of total membrane area, reactor pressure, permeate pressure and natural gas feed rates. A permeate-H₂-to reactor natural gas feed molar ratio >2.3 was achieved with six two-sided membrane panels under steam reforming conditions and a pressure differential across the membranes of 785 kPa. The total cumulative reforming time reached 395 h, while hydrogen purity exceeded 99.99% during all tests.     

Yogurt enrichment with functional asparagus fibre. Effect of fibre extraction method on rheological properties, colour, and sensory acceptance

In the asparagus-processing industry, the by-products constitute around 50% of the total weight. These by-products are rich in fibre and bioactive compounds which could be advantageously employed in human nutrition. In the present work, yogurts were enriched with fibre obtained from the non-edible part of asparagus shoots to assess how the method of extraction (water or ethanol) and then drying (oven or lyophilisation) affects its performance. Fibre incorporation increased the consistency of the yogurts (higher η, G′, G″), especially if the fibres had been extracted in ethanol and lyophilised. However, there were no significant changes in the viscoelastic behaviour (tan δ) for any of the fibre types. Fibres diminished the clarity and imparted a yellow-greenish colour to the yogurt, which also varied depending on the method of extraction and drying, the yogurts with water-extracted fibres being more colourful. The sample more liked according to a consumer test was the yogurt containing water-extracted and oven-dried fibre for aroma, taste, texture, and overall acceptance, and ethanol-extracted and lyophilised for colour. The consumer panel scored all the samples around to the neutral point “neither like nor dislike”, demonstrating that fibre obtained by all methods were equally compatible with yoghurt enrichment.     

Uplink Channel Estimation for Multi-user OFDM-based Systems

In this paper we propose a simple, yet flexible and efficient, channel estimator for the uplink in broadband orthogonal frequency division multiplexing (OFDM) systems. The processing is performed in the time-domain, by extracting the Channel’s Impulse Response (CIR) for each user from a joint training signal. In this OFDM system, the pilot sequence we advocate, where all users share the same pilot sub-carriers, consists of one OFDM-symbol endowed with time-shifted properties per user, which isolates each user’s CIR and is robust against multi-user interference. The feasibility of our approach is substantiated by system simulation results obtained using BRAN-A broadband mobile wireless channel model.

无铅钎料对波峰焊设备的影响

目前,无铅钎料应用的日益推广使得波峰焊设备问题更加突出.其中主要的问题是设备的腐蚀及材料的寿命.为此,许多设备制造商提出了不同的方案来解决此类问题.这些方案涉及范围从不对元件进行改进到使用昂贵的金替代整个钎料锅及喷嘴.本文对制造波峰焊设备"钎料元件"的所用材料进行评估.     

正确测量转换速率

转换速率(Slew rate)限定一个放大器输出偏移的最大比率.它确定不失真带宽(ADC驱动电路的一个重要参数)的极限.转换速率还影响DAC输出级、滤波器、视频放大器以及数据采集器可能达到的性能.如果你的电路性能依赖这一参数,你就必须通过测量来验证放大器的转换速率.     

Advanced Adaptive Sonar for Mapping Applications

An advanced adaptive sonar module is described, capable of being configured to different circumstances and distances according to reflectors found in the environment. Thanks to the sensory distribution, it is possible to identify three basic types of reflector (planes, edges and corners). Furthermore, a heuristic map of the environment is built. The proposed methods have been computationally optimized, and implemented in a real-time system based on a Field-Programmable Gate Array (FPGA) and a Digital Signal Processor (DSP). Results have been obtained in the detection, classification and mapping of obstacles; and finally testing has been carried out on a commercial vehicle.     

用于公交车辆的电子动力传动系统将揭开面纱

Adura系统已经在公交汽车和多功能汽车的传动系统中秘密工作了两年,其使得这些车辆的燃料系统更经济,排放等级也得以提高.这种系统是由加州一家公司开发的,包含了高度模块化的系统电子部件,一个智能控制软件平台,以及首个工业用现场安装能量储存系统.该储存装置可根据25、50或100英里初始行程配置在纯电子模块中,进而进行后续的混合工作.