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341.
《International Journal of Hydrogen Energy》2021,46(56):28486-28500
Low-rank lignite is among the most abundant and cheap fossil fuels, linked, however, to serious environmental implications when employed as feedstock in conventional thermoelectric power plants. Hence, toward a low-carbon energy transition, the role of coal in world's energy mix should be reconsidered. In this regard, coal gasification for synthesis gas generation and consequently through its upgrade to a variety of value-added chemicals and fuels constitutes a promising alternative. Herein, we thoroughly explored for a first time the steam gasification reactivity of Greek Lignite (LG) and its derived chars obtained by raw LG thermal treatment at 300, 500 and 800 °C. Moreover, the impact of CO2 addition on H2O gasifying agent mixtures was also investigated. Both the pristine and char samples were fully characterized by various physicochemical techniques to gain insight into possible structure-gasification relationships. The highest syngas yield was obtained for chars derived after LG thermal treatment at 800 °C, due mainly to their high content in fixed carbon, improved textural properties and high alkali index. Steam gasification of lignite and char samples led to H2-rich syngas mixtures with a H2/CO ratio of approximately 3.8. However, upon co-feeding CO2 and H2O, the H2/CO ratio can be suitably adjusted for several potential downstream processes. 相似文献
342.
l-Valinium Aluminium Chloride (LVAC), a novel semi-organic material, was grown using slow evaporation under isothermal condition. The single crystal data reveal that the grown crystal belongs to monoclinic system. The SEM micrographs give clear picture about the surface morphology. Further, they confirm the inclusion of aluminium chloride into atomic sites of l-Valine. The compositional elements present in the crystal were identified through EDAX analysis. The mass spectral analysis was carried out to determine the molecular weight of the grown crystal. The optical transparency of the grown crystal was investigated by UV–vis–NIR spectrum. FTIR spectral study was used to identify the functional groups present in the grown material. The luminescence characteristics of grown material were analysed to confirm the effect of metal ion on the ligand. This property makes the material suitable for OLED application. The supercapacitive performance of the grown crystal was finally studied using cyclic voltammetry. 相似文献
343.
This paper introduces a packet-based dual-rate control strategy to face time-varying network-induced delays, packet dropouts and packet disorder in a Networked Control System. Slow-rate sensing enables to achieve energy saving and to avoid packet disorder. Fast-rate actuation makes reaching the desired control performance possible. The dual-rate PID controller is split into two parts: a slow-rate PI controller located at the remote side (with no permanent communication to the plant) and a fast-rate PD controller located at the local side. The remote side also includes a prediction stage in order to generate the packet of future, estimated slow-rate control actions. These actions are sent to the local side and converted to fast-rate ones to be used when a packet does not arrive at this side due to the network-induced delay or due to occurring dropouts. The proposed control solution is able to approximately reach the nominal (no-delay, no-dropout) performance despite the existence of time-varying delays and packet dropouts. Control system stability is ensured in terms of probabilistic Linear Matrix Inequalities (LMIs). Via real-time control for a Cartesian robot, results clearly reveal the superiority of the control solution compared to a previous proposal by authors. 相似文献
344.
《Ceramics International》2022,48(8):10827-10833
The fatigue properties of lithium hydride (LiH) are crucial to its application as neutron shielding and moderating at elevated temperatures. The dynamic fatigue tests of LiH were investigated with the notched 3-point bend (3 PB) specimens over ranges of loading rates at RT up to 400 °C. At RT, the results showed that slow crack growth (SCG) occurred prior to failure as the minor deviation from linearity to nonlinearity in the load-deflection curves. In addition, the fracture strength of LiH decreased with decreasing stress rate and the SCG zone gradually became smaller with higher stress rates, indicating evident dynamic fatigue phenomenon. However, the trends were quite different at 200, 300 and 400 °C due to accumulative creep damage for low stress rates at elevated temperatures. With increasing temperature and decreasing stress rate, there existed a transition of the dominated failure mechanism, from SCG to creep rupture. Evidence of very small SCG zone could also be detected at the notch for the failure dominated by creep rupture. 相似文献
345.
锆离子轰击Zr-4的腐蚀行为及其慢正电子谱研究 总被引:1,自引:0,他引:1
为了研究锆离子轰击对Zr-4合金锆耐蚀性的影响,用金属蒸汽真空弧(MEVVA)源对纯锆样品进行了1?015 至2?017 cm-2 的锆离子轰击,加速电压为50 kV。用X-射线光电子谱(XPS)对轰击表面各元素进行价态分析;用俄歇电子能谱(AES)分析氧化膜厚度。对轰击样品进行3次极化测量,以评价轰击样品在1N 硫酸溶液中的耐蚀性。利用慢正电子谱研究了轰击样品表面的缺陷情况。研究结果表明:除1×1015cm-2剂量外,轰击样品的耐蚀性都好于空白Zr-4,且5×1016 cm-2离子轰击样品的耐蚀性最好,轰击样品的自腐蚀电位大体上随着剂量的增加而下降。轰击Zr-4样品的腐蚀行为与其慢正电子谱之间存在着一定的对应关系。 相似文献
346.
In this paper, we demonstrate the unique ability of a newly developed slow-trap profiling technique to characterise silicon-based MOS capacitors in strong inversion. We also demonstrate the applicability of the slow-trap profiling technique for the characterisation of oxides grown on SiC. The obtained slow-trap profiles show that NO nitridation eliminates while N2O creates defects acting as slow traps in the case of both Si and SiC substrates. The corresponding effects of nitridation on interface traps and fixed oxide charge are also discussed. 相似文献
347.
In order to elucidate the effect of nanopores and organic matters on sequestration of contaminants, short- and long-term sorption and desorption of naphthalene and pyrene in seven artificial solid-water systems were studied. Fast sorption occurred in every case; steady states were reached within 1-5h. Sorption constants varied drastically among the seven absorbents, ranging from 1.19 to 5.29 x 10(3) for naphthalene, and from 24.3 to 6.52 x 10(4) for pyrene. Slow sorption continued to take place in some cases, especially on absorbents containing humic matter. Desorption usually took place in two stages, fast and slow, on both unaged and aged absorbents. Irreversibility of desorption occurred for every absorbent except for silica particles modified with octadecyl silyl. Aging led to a reduction of fast desorption fraction due to entrapment of the chemicals into nanopores and partitioning of the chemicals into condensed areas of humic matters, and showed no effect on slow desorption and irreversibility of desorption. On the whole, entrapment into nanopores and partitioning into humic matters are considered to be important for sequestration of contaminants. Irreversibility of desorption is considered to be a more influencing factor than percentage of desorption for describing the extent of sequestration. 相似文献
348.
349.
350.
WANG Bao-Yi YU Run-Sheng ZHAO Fa-Ru MA Chuang-Xin ZHANG Tian-Bao WEI Long 《核技术(英文版)》2004,15(4):213-215
Two types of porous metal moderators (i.e. porous nickel layer and multi-wire tungsten layer) are proposed and tested on a slow positron beam line. A moderation efficiency of about 2×10-4 has been achieved, which is higher than that for W vane geometry moderator by a factor of 4. 相似文献