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991.
992.
Yannan Zhang Peng Dong Jinbao Zhao Xue Li Yingjie Zhang 《Ceramics International》2019,45(9):11382-11387
The porous Fe2TiO5 particles are successfully synthesized through a facile one step solution combustion method. The Fe2TiO5 negative materials exhibit remarkable electrochemical performance with discharge capacities of 371.4?mAh g?1 at the 100 th cycle, and display promising rate stability with discharge capacities 76.6?mAh·g?1 at a high current density of 3.2?A?g?1. In addition, the mechanism of electrochemistry reaction is illustrated by the CV, raman and EIS measurements, the irreversible capacity mainly causes from the irreversible lithium insertion at 1.8?V. The results indicate that the one step solution combustion synthesis of porous Fe2TiO5 is a promising strategy for developing low-cost and high-performance Ti-based negative materials. 相似文献
993.
Cloud computing enables the provisioning of resources in a reliable and on-demand manner. With the increasing importance of the network bandwidth in the Cloud environment, the networking related resources need to be optimally allocated together with the traditional Cloud computing resources. In addition, the significant growth of the global data center traffic raises the challenge of supporting demands with large bandwidth requirements for the Cloud provider. In our paper, we consider the network-efficient virtualized cloud infrastructure provisioning problem in IP over elastic optical network (IP-over-EON) based on the data center as a service model. The elastic optical network is adopted to provide spectrum and cost-efficient networking resources for large bandwidth requests in our work. We develop mixed integer linear programming formulations to construct the mathematic model for this problem and propose a cost-optimized heuristic to solve this problem. To investigate the cost and blocking rate for the served demands, different modulation formats are compared in the EON layer, and the sliceable bandwidth-variable transponders and optical traffic grooming technology are considered. The experimental results show that different modulation formats that are adopted in the EON layer will have different impacts on the total cost and demand blocking rate for the same data set size. Also the use of SBVT will reduce the total cost no matter which modulation format is adopted, and the reduction is related to the bandwidth requirement of the demands. 相似文献
994.
冉燊铭 ' target='_blank'> 潘绍成 ' target='_blank'> 刘宇钢 ' target='_blank'> 唐勇 ' target='_blank'> 霍锁善 ' target='_blank'> 《中州煤炭》2019,(8):108-113
根据反平衡法对电站锅炉各项效率损失进行分析,潜力较大的是排烟损失和未完全燃烧损失,主要影响因素有过量空气系数、排烟温度、燃烧效率;1 000 MW高效宽负荷率超超临界煤粉锅炉的开发采用低过量空气系数设计理念,在炉膛选型、受热面布置、燃烧系统设计、降低锅炉漏风等方面采取措施。与传统设计相比,50% THA负荷下锅炉效率提升了0.96%。 相似文献
995.
Yun-Han Su Cheng-Tang Pan Yu-Sheng Tseng Ji Zhang Wen-Fan Chen 《Ceramics International》2021,47(14):19414-19423
Cerium (Ce)-substituted diopsides (CaMgSi2O6) with enhanced mechanical strength and bioactivity were fabricated by precipitation method, followed by annealing at 1000 °C for 4 h. The mineralogical, morphological, in vitro biomineralization, degradation, and mechanical properties were investigated in order to assess the factors and mechanisms affecting the resultant properties. The X-ray diffractometer results showed that the onset of substitutional solid solubility in 0.25 mol Ce would result in new phase formation (cerium dioxide [CeO2], and magnesium silicate [MgSiO3]) further causing lattice instability. With increasing Ce dopant levels to 1.00 mol, the initial CaMgSi2O6 phase was completely replaced by new phases. The field-emission scanning electron microscopy results indicated that the 0.25 mol Ce had the best biomineralization performance in vitro, while less hydroxyapatite precipitates were found with further increasing Ce dopant levels, suggesting the new phases led to the hindrance of precipitates. The weight loss values indicated that the high dissolution rate of ions in the matrix was observed in the pure sample, while the high readsorption rate of ions in the simulated body fluid (SBF) occurred with increasing Ce dopant levels. The pH value and the inductively coupled plasma-mass spectrometer results suggested that the release of Ca and Mg ions controlled the pH value. The mechanical strength of matrices before SBF immersion was related to the phase transformation, the elastic modulus of CeO2 and CaMgSi2O6, and the release of Mg ions, while the mechanical strength of matrices after SBF immersion was dominated by the structure of matrices. 相似文献
996.
Xiao Zhang Zhao Yang Xin Huang Xingyu Wang Yuelei Pan Xiaomeng Zhou 《International Journal of Hydrogen Energy》2021,46(41):21704-21714
Hydrogen enriched with compressed natural gas is an efficient and environment-friendly gaseous fuel. However, the safety issues of mixture and the method to control or weaken their combustion are highly concerned. To explore the inhibition effect of halogenated fire suppressants on the mixture, the effect of HFC-227ea on the laminar premixed methane/air flames, with different fractions of H2, have been studied. Burning velocities have been measured with constant-volume combustion chamber and kinetically modelled a recently assembled kinetic mechanism. The fractions of H2 influence the enhancement and inhibition effect of HFC-227ea, and it is less effective with the lean mixture. In stoichiometric condition, HFC-227ea showed good inhibition effect on the mixture flames. The HFC-227ea increased the burning velocities of CH4-0% H2-air and CH4-10% H2-air flames at leanest condition, whereas the increased burning velocity arising from HFC-227ea not occurred as the addition of H2 above 20%. Experimental results coincided well with numerical results, however the agreement was poor for the leanest flames at low agent loading. Lastly, kinetic mechanism analysis was used to interpret the combustion enhancement and inhibition effect of hydrogen-doped methane flame by HFC-227ea. 相似文献
997.
Eugene Wai Keong Koh Cheng Hsin Chiu Yao Kun Lim Yong-Wei Zhang Hui Pan 《International Journal of Hydrogen Energy》2012
We investigate the hydrogen adsorption on and diffusion through the MoS2 monolayer based on density-functional theory. We show that the hydrogen atom prefers to bond to the S atom at the monolayer, leading to enhanced conductivity. The hydrogen atom can also adsorb at the middle of the hexagon ring by overcoming an energy barrier of 0.57 eV at a strain of 8%. Also, we show that the MoS2 monolayer is flexible and any mechanical deformation of the monolayer is reversible because the extension of the Mo–S bond is much smaller than the applied strain. The monolayer can block the diffusion of hydrogen molecule from one side to the other due to a high energy barrier (6.56 eV). However, the barrier can be reduced to 1.38 eV at a strain of 30% and even totally removed by creating S vacancies and applying a strain of 15%. The MoS2 monolayer may find applications in sensors to detect hydrogen, and as mechanical valve to control the concentration of hydrogen gas. 相似文献
998.
999.
1000.
Xiaojun Xu Hao Deng Cunyun Pan Haijun Xu 《Journal of Mechanical Science and Technology》2014,28(3):953-961
A quadrilateral with four invariable lengths of sides has the characteristic of transforming the variation of the diagonal length to the variation of its interior angle. Thus, the combination of two quadrilaterals with a cam forms the differential velocity drive mechanism (DVDM) of a novel twin-rotor piston engine (TRPE). The DVDM restricts the two coaxial rotors to rotate with periodical but nonuniform velocity, and the volume of working chambers created by the adjacent vane pistons of the two rotors alternately expands and then contracts. The volumetric change of working chambers is used to generate the four-stroke engine cycle. The kinematic model and the detailed position, velocity, and acceleration analysis results of the TRPE are presented. The results show that this novel engine, associated with the advantages of higher uniformity of torque and power density due to multiple power strokes per revolution of the output shaft, has a compact and totally balanced design. 相似文献