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331.
332.
Chunying Xu Zhilei Wu Chenjuan Fan Lili Yan Wenmin Wang Baoming Ji 《中国稀土学报(英文版)》2021,39(9):1082-1088
Two isostructural tetranuclear lanthanide clusters named [Ln4(L)4(CH3O)4]·CH3OH (Ln = Gd(III) for 1, Dy(III) for 2, H2L = N′-(2-hydroxy-3-methoxybenzylidene)-6-(hydroxymethyl) picolinohydrazide) were successfully isolated by using a polydentate Schiff based ligand and Ln(III) nitrate salts. The structures of 1 and 2 were characterized by X-ray structural analyses, they are held by four double deprotonated ligands L2−. In them all the lanthanide ions are eight-coordinated and distributed over four vertices of a parallelogram, presenting a Ln4 cluster with a strict [2 × 2] square grid pattern. The details of magnetic analysis show that 1 displays weak anti-ferromagnetic exchange between neighboring Gd(III) ions through carboxylate oxygen and methanol oxygen ligand atoms. Furthermore, 1 exhibits significant magnetocaloric effect with the maximum entropy change –ΔSm value of 28.5 J/(kg·K) for ΔH = 7.0 T at 2.0 K. For compound 2, remarkable slow magnetic relaxation behaviors are observed in the presence of zero magnetic field with τ0 = 1.02 × 10−6 s and energy barrier ΔE/kB = 43.24 K. 相似文献
333.
The operation of wind turbines in the distribution networks may affect the power quality offered to the consumers. One of the most important considerations is the effect on the voltage profile, i.e. the induced slow voltage variations, which are the subject of this paper. Two alternative approaches are presented for their evaluation. The first, adopted by many utility guides and recommendations, is deterministic, seeking to ensure that the voltage deviations always remain within certain limits. The other recognises the statistical nature of the voltage variations and conforms to latest European Norm, EN 50160. Rather than assessing the maximum deviations that can possibly appear, the probability distribution of the voltage is calculated and then the conformity to the standards is assessed. In applying the statistical method, either time series, or directly probability distributions can be used. As a study case, the methods are applied to an existing MV distribution feeder, where significant wind power is installed. Measurement data are provided for the same feeder. 相似文献
334.
7075铝合金应力腐蚀敏感性的SSRT和电化学测试研究 总被引:4,自引:0,他引:4
采用慢应变速率试验(SSRT)研究了7075铝合金的应力腐蚀行为。试验结果表明,外加阳极极化和阴极极化都能增加7075铝合金的应力腐蚀敏感性,即使在弱极化情况下也能显著增加合金的应力腐蚀敏感性。但是,外加极化对于不同热处理状态的7075铝合金,其应力腐蚀敏感性增加的程度不同。电极极化对T6状态合金的SCC敏感性的影响显著,而对RRA和T7351状态合金的影响较轻微。随着拉伸应力的增加,7075-RRA铝合金的阳极极化曲线略向正移,滞后环面积扩大,但并不显著。 相似文献
335.
300M超高强度钢的应力腐蚀开裂 总被引:2,自引:0,他引:2
利用慢应变率拉伸试验技术研究了300M超高强度钢的应力腐蚀开裂(SCC),结果表明,300M钢在3.5%NaCl水溶液和蒸馏水中均对SCC敏感,随温度增加和拉伸应力变速率的降低钢的SCC敏感性增加,并且阴极极化和阳极极化均提高钢的SCC敏感性,除氧和降低溶液pH值均提高钢的SCC敏感性。 相似文献
336.
《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
337.
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
338.
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
339.
《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
340.
The effects of process-induced disorder location on planar photonic crystal waveguide properties are numerically investigated using three-dimensional finite difference time domain simulation by introducing random fluctuations of the hole radius, size, position, and shape of air-holes of two-dimensional planar photonic crystal slab. Results reveal that bandgap properties are extremely robust with respect to disorder. It is shown that the very first rows of holes play a major role in the amount of disorder-induced optical loss, and that keeping the first two rows of holes unchanged leads to a blue-shift of slow light waveguide properties. 相似文献