Optimal design of an experimental methanol fuel reformer

We report on the steady state modeling of an experimental methanol fuel reformer for fuel cell applications. The fuel reformer consists of an AutoThermal Reformer (ATR) followed by an Oxygen Removal (OR) reactor, Steam Reformer (SR) and Water Gas Shift (WGS) reactor. The effluent from the WGS is fed to a series of three Preferential Oxidation (PROX) reactors that reduce the CO concentration to less than 40 ppm. A mathematical model of the reformer is developed and selected parameters of the model are fit to experimental data collected from a fuel reformer that was designed, built and operated by the Material and Chemical Research Laboratories (MCL) of the Industrial Technology Research Institute (ITRI) in Hsinchu, Taiwan. In order to develop a compact and high-performance fuel reformer system, the mathematical model is used to design a reformer that has the minimum possible combined volume of the steam reformer and water gas shift reactor. The result is that the volume of the optimized reactor units can be reduced by 17.2% without a significant change in the overall efficiency.     

硬岩巷道高效掘进爆破技术探究

以硬岩巷道高效掘进爆破技术为对象开展探究,结合具体工程实际,对硬岩巷道掘进爆破参数开展优化分析,并对其实际应用方式及效果做出探究,希望能够为其他矿井相似工程的开展提供借鉴和参考.     

背压对敞口型旋流喷嘴液膜特性影响的数值研究

背压对空气物性影响较大,使喷嘴液膜受到的气动力发生大幅变化。采用计算流体力学（Computational Fluid Dynamics,CFD）方法对比3种常见液体工质和3种喷嘴尺寸,研究背压对雾化锥角、液膜厚度、旋流强度、液膜表面自激励不稳定性以及液膜形态的影响。结果表明：雾化锥角随背压增加而减小,其中部分喷嘴当背压达到某定值后,雾化锥角小幅波动;选用正庚烷或正十二烷为工质时,液膜厚度随背压增加而增加,达到一定背压后,3种液体液膜厚度呈小幅波动;旋流强度随背压变化无明显规律性;液膜自激励不稳定性随背压增加而降低;因水的表面张力较大,各雾化参数较为稳定;液膜形态与韦伯数呈明显规律性,背压越小韦伯数越大,液膜形态也更趋近于完美圆锥形;以正十二烷为工质时,其液膜形态在大背压下明显收缩,呈洋葱形,其余工质的液膜形态随背压增加,均逐渐从空心圆锥转变为郁金香形。     

基于系统性能的近地告警技术研究

基于多种导航信息综合处理、告警计算的近地告警系统,对于避免可控撞地事故、提升飞机安全具有重要意义.本文首先介绍了近地告警系统的工作原理,研究了基于SOC曲线的告警包线设计技术,并以过大近地速率告警模式为例进行了告警包线的仿真.最后,利用实际飞行数据分析验证了告警包线合理性以及导航信息可靠性对系统性能的影响.     

Magnetic contributions to the thermodynamic functions of pure Ni,Co, and Fe

An empirical mathematical equation is proposed for the magnetic contribution to the specific heat of pure metals. The corresponding functions for enthalpy, entropy, and Gibbs energy are of simple form. Two parameters used for each element are the critical temperature,T _c, and the total magnetic entropy. The parameters have been determined from a careful separation of magnetic and nonmagnetic contributions to the specific heat. Debye temperatures for Ni, Co, and Fe have been determined considering data to much higher temperatures than other studies. The magnetic specific heats extracted from experimental data agree very well with the proposed equation over the entire temperature range and for all three elements. Comparisons with different mathematical functions found in the literature give agreement only for the case of iron. The total magnetic entropy given by a classical relation is found to be high, and a quantitative correction is given. Various magnetic standard states are discussed. The lattice stabilities of bcc- and fcc-iron are calculated assuming that the difference of the nonmagnetic specific heats is linear from 500 K to 1810 K. A simple equation is obtained in which the anomalous temperature dependence is explained by the independently determined magnetic contribution. The calculated values agree very well with Orr and Chipman’s assessment. The stability of bcc iron at low temperatures is quantitatively rationalized.     

The extraction of platinum from Pt(II) chloride solution by a quaternary ammonium compound

The fundamental aspects of the extraction and stripping of platinum (II) from its chloride solution by Aliquat 336 diluted with toluene have been studied. The extraction and stripping was at 99.5 and 97.6% equilibrium within 30 s and 20 min respectively. The percentage extraction increased slightly with decreasing hydrochloric acid concentration. In 0.1 mol dm^?3 hydrochloric acid, 1.0 volume percent Aliquat 336 in toluene could load 9.8 mmol dm^?3 of platinum (II). The percentage stripping of platinum (II) from Pt(II)-load organic solvent increased with increasing sodium bisulphite concentration. The enthalpy changes of extraction and of stripping were 12.8 and 114.9 kJ mol^?1 respectively. Both of the reactions were endothermic.     

Soft-output equalization and TCM for wireless personalcommunication systems

This paper investigates the use of a maximum a posteriori probability (MAP) algorithm to realize soft-output equalization in a concatenated equalization and trellis-coded modulation (TCM) decoding-based wireless communication system. Specifically, we first begin with a general MAP algorithm and then focus on studying Bahl's (1974) MAP and Lee's (1974) MAP algorithms. We then propose a modified version of Lee's MAP algorithm which is much simpler than the original, in terms of complexity, and is more practical. In particular, a very simple channel estimation method which employs orthogonal training sequences is proposed. In order to improve the system performance, equal-gain combining and selection diversity are also considered. Finally, we compare the performance of the MAP algorithm-based equalization with our previously proposed equalization scheme, which combines decision feedback equalization and TCM     

Identification of heat load loops and downstream paths in heat exchanger networks

To achieve the optimal trade-off between economies and operability, simplifications of heat exchanger networks (HENs) are required. To do so, identifications of heat load loops and downstream paths are necessary. This paper proposes new methods for identifications of independent and dependent loops as well as downstream paths in HENs, respectively. Stream table and node adjacency matrix are defined in this paper to represent the structures of HENs. Based on graph theory, identification of loops in HENs is decomposed into three procedures: (a) finding a maximal tree, (b) identifying a maximal set of independent loops and (c) searching all loops. Locating the downstream paths in HENs is accomplished by finding directed trees which are generated by modifying the procedure for finding a maximal tree. A complex network with a splitting stream is used for detailed illustrations of the procedures.     

Factors associated with the therapeutic efficacy of retinoic acids on malignant lymphomas

We recently reported the successful use of retinoic acids in the treatment of refractory lymphoma. The biologic determinants predicting response of lymphomas to retinoic acid remain unknown. This study was conducted to explore this question using in vitro models. Sensitivity of representative lymphoma cells to 13-cis-retinoic acid was determined. Sensitive and resistant cell lines were then compared for their baseline and/or retinoic-acid-regulated expression of total cellular retinoic acid binding protein, retinoic acid receptor (RAR)-alpha, RAR-beta, RAR-gamma mRNA, retinoid X receptor (RXR)-alpha, RXR-beta, RXR-gamma mRNA, transforming growth factor (TGF)-beta 1 and TGF-beta 1 receptors, and Fas (Apo-I) mRNA. The results showed that four of five T, two of three Hodgkin's, and none of six B cell lymphoma cell lines were sensitive (IC30 < 1.5 mmol/L) to 13-cis-retinoic acid. Further analyses revealed several of the above-mentioned parameters may be relevant to retinoic acid sensitivity. Baseline expression of TGF-beta 1 receptors was present in all of the five sensitive cell lines examined, but in only one of the four resistant cell lines. The correlation of Fas expression and retinoic acid sensitivity was good for B cell lines, but not apparent for T cell or Hodgkin's cell lines. On exposure to retinoic acid, an immediate and prolonged upregulation of RAR-alpha mRNA expression, lasting for more than 12 hours, occurred in all sensitive cell lines, but only minimal or transient induction was seen in resistant cells. Together, these data suggested that; 1) retinoic acid has a preferential effect on T cell and Hodgkin's lymphoma cell lines; 2) autoregulation of RAR-alpha by retinoic acids, and the presence of TGF-beta 1 receptors may be relevant to the response of lymphomas to treatment with retinoic acids.     

The effect of education on mortality among older Taiwanese and its pathways

The present research examines the impact of education on the mortality of older Taiwanese during a 4-year interval from April 1989 to April 1993. Data used for this study come from the Taiwan Survey of Health & Living Status of the Elderly (1989). The research decomposes the effect of education into the direct effect and the indirect effects by means of health status, health behaviors, and social relationships. We have shown that, of the total effect of educational attainment on the mortality of older Taiwanese, about 83% represents indirect influences by means of the 3 mediating factors, particularly health status. On the other hand, the magnitude of the direct effect, which might reflect influences of additional intervening variables on old-age mortality, is low and not statistically significant. The results demonstrate that the apparent strong effect of education on mortality among older Taiwanese can be accounted for parsimoniously through 3 major pathways.