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1.
The effect of ultrasound on the kinetics of anti-solvent crystallization of sucrose was studied. The influence of temperature, stirring rate, supersaturation and ultrasonic power on the anti-solvent crystallization of sucrose was investigated. The relationship between infrared spectral characteristic band of sucrose and supersaturation was determined with an online reaction analyzer. The crystal size distribution of sucrose was detected by a laser particle-size analyzer. Ultrasound accelerated the crystallization process, and had no impact on the crystal shape. Abegg, Stevens and Larson model was fitted to the experimental data, and the results were the following: At 298.15 K, the average size of crystals was 133.8 μm and nucleation rate was 4.87 × 109 m−3·s−1 without ultrasound. In an ultrasonic field, the average size was 80.5 μm, and nucleation rate was 1.18 × 1011 m−3·s−1. Ultrasound significantly reduced the average size of crystals and improved the nucleation rate. It was observed that the crystal size decreased with the increase of stirring rate in silent environment. When the stirring rate increased from 250 to 400 rpm, the average size decreased from 173.0 to 132.9 μm. However, the stirring rate had no significant impact on the crystal size in the ultrasonic field. In addition, the activation energy of anti-solvent crystallization of sucrose was decreased, and the kinetic constant of nucleation rate was increased due to the effect of ultrasound. In the ultrasonic field, the activation energy was reduced from 20422.5 to 790.5 J·mol−1, and the kinetic constant was increased from 9.76 × 102 to 8.38 × 108.  相似文献   
2.
Having shown promising performance with high flexibility and efficiency in vehicular edge computing (VEC) network, the parked vehicles (PVs) received an increasing number of attentions in recent years. However, PVs’ residual battery power restricts their running time. In addition, there is still no alternate resource pool for the PVs to cope with the emergencies in the previous VEC framework. To alleviate these problems, we model a cloud-assisted parked vehicular edge computing (PVEC) framework, in which the PVs are classified based on their residual battery power. PVs corporate with the cloud servers (CSs) for the computational resources provision. In addition, we formulate the utilities of the service provider (SP) and PVs and design a contract-based resource allocation problem for the maximization of the SP’s utility. Considering that it is intractable to solve the optimization problem directly, the primal problem is simplified and decoupled into two sub-problems. To design the optimal contracts, we solve the sub-problems by Lagrangian multiplier method and dual function. Simulation results prove that the utilities of PVs can reach to the maximum when they choose the contract corresponding to their types. In addition, the simulation results illustrate the superiority of proposed scheme over previous schemes in improving the utilities of the SP and social welfare.  相似文献   
3.
This paper investigated the effect of Gaussian distribution width, average particle diameter, particle loading, and the tapered angle on minimum fluidization velocity (Umf) by conducting extensive experiments in tapered fluidized beds. Three powders with Gaussian size distribution and different distribution widths were used in the experiments. An increase in Umf with increasing the average particle diameter, particle loading, and the tapered angle was observed. There was also a nonmonotonic behavior of Umf as the Gaussian distribution width increased. An empirical correlation including dimensionless groups for predicting Umf in tapered beds was developed in which the effect of distribution width was considered. The proposed correlation predictions were in good agreement with the experimental data, with a maximum deviation of 16.5% and average and standard deviations of, respectively, 6.4% and 7.4%. The proposed correlation was also compared with three earlier models, and their accuracy was discussed.  相似文献   
4.
延安是中国共产党领导革命的中心和战略总后方,是革命的红色摇篮。延安时期出版了大量具有历史、文化以及教育意义的红色文献,这些红色文献记载了中国共产党波澜壮阔的发展历程,也反映了延安时期不断发展的科技生产水平与独特的制浆造纸工艺,具有重要的研究价值。然而,延安时期出版的红色文献虽距今不到百年时间,但其保存现状不容乐观,普遍存在纸张老化、焦脆易碎等问题,大量文献急需科学检测与修复保护,以延长其保存寿命。目前,针对延安时期红色文献的检测研究仍存在较大空白。考虑到红色文献的珍贵性与特殊性,应当尽可能选择无损检测方法对其分析检测。基于衰减全反射-傅里叶变换红外光谱法(ATR-FTIR),以木素1 510 cm-1处特征峰与纤维素1 030 cm-1处特征峰的强度作为定量依据,建立了造纸原料与红色文献纸张中木素相对含量的无损检测方法。通过检测不同碱强度与碱浓度处理后的构皮、苦竹与杨木的木素含量,考察了制浆过程中碱处理条件对造纸原料脱木素程度的影响,同时体现了红外光谱法测定木素相对含量的普适性。以复旦大学图书馆藏的76册延安时期红色文献为研究对象,分析了红色文献的纸张木素含量与纸张pH值以及纸张氧化度的相互关系。结果表明,木素相对含量高于25%的红色文献,其纸张pH集中在3~4之间且纸张氧化度较高,文献整体保存状况堪忧;而木素相对含量低于25%的红色文献,其纸张氧化度与酸度较低,文献整体保存情况较好。以上结果验证了红外光谱无损检测法用于延安时期红色文献木素含量分析的可行性,并结合纸张氧化度与酸度数据提出了纸张木素含量的合适范围,为制浆造纸中植物原料的脱木素过程提供参考。拓展了红外光谱法在红色文献无损检测中的应用范围,以期为延安时期红色文献的修复与保护研究提供科学依据。  相似文献   
5.
Present study offers great prospects for the adsorption of anti-inflammatory celecoxib molecule (CXB) over the surface of zinc oxide (Zn12O12) and magnesium oxide (Mg12O12) nanoclusters in several environments by performing robust theoretical calculations. Density functional theory (DFT), time-dependent density functional theory (TDDFT) and molecular docking calculations have been extensively carried out to predict the foremost optimum site of CXB adsorption. It has been observed that the CXB molecule prefers to be adsorbed by its SO2 site on the Zn-O and Mg-O bonds of the Zn12O12 and Mg12O12 nanoclusters instead of NH2 and NH sites, where electrostatic interactions dominate over the bonding characteristics of the conjugate complexes. Furthermore, the presence of interactions between the CXB molecule and nanoclusters has also been evidenced by the UV–Vis absorption spectra and IR spectra. Molecular docking analysis has revealed that both adsorption states including CXB/Zn12O12 and CXB/Mg12O12 have good inhibitory potential against protein tumor necrosis factor alpha (TNF-α) and Interleukin-1 (IL-1), and human epidermal growth factor receptor 2 (HER2). Hence they might be explored as efficient TNF-α, IL-1, and HER2 inhibitors. Hence from the study, it can be anticipated that these nanoclusters can behave as an appropriate biomedical carrier for the CXB drug delivery.  相似文献   
6.
建立了氟化氢铵消解地球化学样品,电感耦合等离子体质谱(ICP-MS)法测定样品中钨、锡和钼的方法。方法经过国家土壤和水系沉积物标准参考物质验证,方法的检出限钨为0.048μg/g、锡为0.079μg/g、钼为0.063μg/g,准确度(相对误差)钨为0.64%~6.28%、锡为0.29%~3.74%、钼为2.12%~7.41%,精密度(相对标准偏差)钨为0.13%~0.72%、锡为0.05%~1.2%、钼为0.03%~1.1%,能够满足《地质矿产实验室测试质量管理规范》的质量要求。方法具有操作简便、测试成本低、分析效率高、环境污染小等特点,适合于批量样品的分析测试。  相似文献   
7.
李军  姚道新 《中国物理 B》2022,31(1):17403-017403
This article reviews the basic theoretical aspects of octagraphene, an one-atom-thick allotrope of carbon, with unusual two-dimensional(2 D) Fermi nesting, hoping to contribute to the new family of quantum materials. Octagraphene has an almost strongest sp2hybrid bond similar to graphene, and has the similar electronic band structure as iron-based superconductors, which makes it possible to realize high-temperature superconductivity. We have compared various possible mechanisms of superconductivity, including the unconventional s;superconductivity driven by spin fluctuation and conventional superconductivity based on electron–phonon coupling. Theoretical studies have shown that octagraphene has relatively high structural stability. Although many 2 D carbon materials with C;carbon ring and C;carbon ring structures have been reported, it is still challenging to realize the octagraphene with pure square-octagon structure experimentally.This material holds hope to realize new 2 D high-temperature superconductivity.  相似文献   
8.
As one of the most attractive non-radiative power transfer mechanisms without cables,efficient magnetic resonance wireless power transfer(WPT)in the near field has been extensively developed in recent years,and promoted a variety of practical applications,such as mobile phones,medical implant devices and electric vehicles.However,the physical mechanism behind some key limitations of the resonance WPT,such as frequency splitting and size-dependent efficiency,is not very clear under the widely used circuit model.Here,we review the recently developed efficient and stable resonance WPT based on non-Hermitian physics,which starts from a completely different avenue(utilizing loss and gain)to introduce novel functionalities to the resonance WPT.From the perspective of non-Hermitian photonics,the coherent and incoherent effects compete and coexist in the WPT system,and the weak stable of energy transfer mainly comes from the broken phase associated with the phase transition of parity-time symmetry.Based on this basic physical framework,some optimization schemes are proposed,including using nonlinear effect,using bound states in the continuum,or resorting to the system with high-order parity-time symmetry.Moreover,the combination of non-Hermitian physics and topological photonics in multi-coil system also provides a versatile platform for long-range robust WPT with topological protection.Therefore,the non-Hermitian physics can not only exactly predict the main results of current WPT systems,but also provide new ways to solve the difficulties of previous designs.  相似文献   
9.
Ruppeiner geometry has been successfully applied in the study of the black hole microstructure by combining with the small–large black hole phase transition, and the potential interactions among the molecular-like constituent degrees of freedom are uncovered. In this paper, we will extend the study to the triple point, where three black hole phases coexist acting as a typical feature of black hole systems quite different from the small–large black hole phase transition. For the six-dimensional charged Gauss–Bonnet anti-de Sitter black hole, we thoroughly investigate the swallow tail behaviors of the Gibbs free energy and the equal area laws. After obtaining the black hole triple point in a complete parameter space, we exhibit its phase structures both in the pressure–temperature and temperature–horizon radius diagrams. Quite different from the liquid–vapor phase transition, a double peak behavior is present in the temperature–horizon radius phase diagram. Then we construct the Ruppeiner geometry and calculate the corresponding normalized curvature scalar. Near the triple point, we observe multiple negatively divergent behaviors. Positive curvature scalar is observed for the small black hole with high temperature, which indicates that the repulsive interaction dominates among the microstructure. Furthermore, we consider the variation of the curvature scalar along the coexisting intermediate and large black hole curves. Combining with the observation for different fluids, the result suggests that this black hole system behaves more like the argon or methane. Our study provides a first and preliminary step towards understanding black hole microstructure near the triple point, as well as uncovering the particular properties of the Gauss–Bonnet gravity.  相似文献   
10.
Liang'an Huo 《中国物理 B》2022,31(3):30202-030202
The appearance of rumors intensifies people's panic and affects social stability. How to control the spread of rumors has become an important issue which is worth studying. In order to more accurately reflect the actual situation in the real world, a stochastic model incorporating media coverage and Lévy noise is proposed to describe the dynamic process of rumor propagation. By introducing two control strategies of popular science education and media coverage in an emergency event, an near-optimal control problem that minimizes the influence and control cost of rumor propagation is proposed. Sufficient conditions for near-optimal control of the model are established by using a Hamiltonian function. Then the necessary conditions for near-optimal control are obtained by using the Pontryagin maximum principle. Finally, the effect of popular science education, media coverage and Lévy noise on rumor propagation process control is verified by numerical simulation.  相似文献   
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