Search

A summary of the diffusion and development of time-geography in East Asia, specifically in Japan and China, is presented in this article. Previous studies have provided reviews of time-geographic research and spacetime behaviour research in both countries. Few studies, however, have told the story about how and why timegeography diffused into East Asia. By showing and analysing the academic life paths of Yoshio Arai and Yanwei Chai, we conclude that the development of time-geography in Japan and China goes hand in hand with their academic progress. Moreover, the interactions within their academic life paths mark some key events that promoted time-geography significantly. The similarities and differences between their academic life paths are also analysed in this article. Both scholars shared some common research topics, such as childcare problems, urban spatial structures and socioeconomic transformations, which were also the most prominent characteristics of time-geography in East Asia. In addition, the socioeconomic backgrounds of their academic life paths are also quite similar, which reflects the close relationship between time-geography and societal needs. Finally, this article discusses the effectiveness and disadvantages of the academic life path method, as the method has proven to be an important tool in analysing the role that key scholars play in promoting a certain discipline. In conclusion, the diffusion and development of time-geography in East Asia can hardly have happened without both individual scholars’ hard work and the exchange and cooperation activities between scholars.

To solve the problems of time consuming, labor consuming and low efficiency in traditional geometric measurement methods, a real-time online measurement system for the electrical parameters of DBD (Dielectric Barrier Discharge) type ozone generator is designed in this paper. With this system, the accuracy and efficiency of electrical parameter measurement are greatly improved. First, the design idea of the proposed measurement system is introduced in detail from hardware circuit systems such as the controller unit circuit, signal detection circuit as well as software systems like data processing unit and result output. Second, the key points of voltage and current of DBD ozone generator at different moments are collected in real time by setting up the experiment platform of real-time online measurement system, and dielectric barrier capacitance, air gap capacitance and discharge power of DBD ozone generator are rapidly calculated. Then, based on the comparison method, the efficiency and accuracy of the main characteristic discharge parameters are verified experimentally. The experimental data show that the realtime online measurement system designed in this paper is more stable than the traditional manual calculation method, and the efficiency is improved by at least two orders magnitude. Finally, the online measurement system is briefly summarized.

Poyang Lake is the largest freshwater lake in China and one of the most important wetlands in the world. Wetland biomass is a key index to weigh the healthiness of wetland ecosystem. Polarimetric information can significantly improve wetland vegetation biomass inversion. In this study, 4 scenes of RADARSAT-2 PolSAR data in year 2011, 2013, 2015 and 2016 were used to estimate the above-ground-biomass (AGB) for the Poyang Lake Wetland. For this purpose, polarimetric decomposition components and a simplified Water-Cloud Model (WCM) were used. The parameters of the simplified WCM were retrieved using the field measurements and the polarimetric decomposition components. Finally, the relationship between the estimated AGB and measured AGB was assessed and the vegetation biomass distribution in year 2011, 2013, 2015 and 2016 were also mapped.

Silicon (Si), germanium (Ge), and gallium arsenide (GaAs) are familiar semiconductors that always act in the role of optical dielectrics. However, these semiconductors also have plasmonic behaviors in ultraviolet (UV) ranges due to the strong interband transitions or valence electrons. And few studies are aimed at investigating plasmonic properties in the semiconductor at the nanoscale. In this work, we discuss UV plasmonics and sensing properties in single and dimer Si, Ge, and GaAs triangular prism meta-antenna systems. The results show that obvious local surface plasmon resonances (LSPRs) can be realized in the proposed triangular prism meta-antennas, and the resonant wavelength, electromagnetic field distribution, surface charge distribution, and surface current density can be effectively tuned by structural and material parameters. In addition, we also find that the Si triangular prism meta-antenna shows more intense plasmonic responses in UV ranges than that in the Ge or GaAs triangular prism nanostructures. Especially, the phase difference between the triangular prism nanostructure and light source can effectively regulate the symbol and value of the surface charge. Moreover, the great enhancement of electric field can be seen in the dimer triangular prism meta-antennas when the distance of the gap is gnm, especially g=1 nm. The most interesting result is that the maximum of refractive index sensitivity s and figure of merit (FoM) are greatly enlarged in dimer triangular prism meta-antennas. Particularly, the sensitivity can reach up to 215 nm/RIU in the dimer GaAs triangular prism meta-antennas, which is improved more than one order of magnitude. These research results may play important roles in applications of the photo detecting, plasmonic sensing and disinfecting in UV ranges.

We investigate Fano resonances and sensing enhancements in a simple Au/TiO2 hybrid metasurface through the finite-different time-domain (FDTD) simulation and coupled mode theory (CMT) analysis. The results show that the Fano resonance in the proposed simple metasurface is caused by the destructive interaction between the surface plasmon polaritons (SPPs) and the local surface plasmon resonances (LSPRs), the quality factor and dephasing time for the Fano resonance can be effectively tuned by the thickness of Au and TiO2 structures, the length of each unit in x and y directions, as well as the structural defect. In particular, single Fano resonance splits into multiple Fano resonances caused by a stub-shaped defect, and multiple Fano resonances can be tuned by the size and position of the stub-shaped defect. Moreover, we also find that the sensitivity in the Au/TiO2 hybrid metasurface with the stub-shaped defect can reach up to 330 nm/RIU and 535 nm/RIU at the Fano resonance 1 and Fano resonance 2, which is more than three times as sensitive in the Au/TiO2 hybrid metasurface without the stub-shaped defect, and also higher than that in the TiO2 metasurface reported before. These results may provide further understanding of Fano resonances and guidance for designing ultra-high sensitive refractive index sensors.

We study dual-Fano resonances and its sensing properties in a crossed ring-shaped metasurface by use of the finite-different time-domain (FDTD) simulation. The results show that the dual-Fano resonances in the proposed crossed ring-shaped metasurface are caused by the interaction among three local surface plasmon resonances (LSPRs), and the spectra of dual-Fano resonances can be tuned by the radius of the circular ring (CR) nanostructure, the distance between the center of the two CRs in x direction, and the polarization of the incident light. Interestingly, single Fano resonance splits into dual-Fano resonances in the case of asymmetric ring structure arrangement or non-y-axis polarized incident or the distance d

With the rapid development of e-commerce platforms, how to quickly sort out and summarize a large number of product reviews on e-commerce websites has become an urgent problem. Product attribute extraction is one of the methods to solve this problem. Automatic extraction of product attributes is one of the important research contents in the field of natural language processing. A product attribute extraction method based on affinity propagation clustering algorithm and pointwise mutual information pruning is proposed to extract product attributes comprehensively and rapidly. Firstly, candidate product attribute sets are obtained from the corpus according to predefined syntactic rules. Then, the candidate product attribute sets are represented by word vectors and calculating the similarity of attribute words to cluster the candidate attribute sets. Thus the candidate attribute clusters are obtained. At last, the effectiveness of the method is proved in a Chinese product review.

Focusing on the realization of excellent sensing for graphene-based metasurface in the terahertz band. A planar monolayer graphene metasurface is proposed for sensing. Dual plasmon induced transparency (dual-PIT) phenomenon is realized in our proposed metasurface by use of the finite-difference time-domain (FDTD) method. This dual-PIT transmission spectrum can be effectively modulated by Fermi energies and positional parameters, and triple-PIT phenomenon can be realized. Interestingly, the excellent sensing performance can be achieved in terahertz band. The maximum sensitivity and Figure of Merit (FOM) are of 4.1884 THz /RIU and 43.31, respectively. These results may play an important role for designing excellent plasmonic graphene-based modulators and sensors in terahertz.

Isobaric vapor-liquid equilibrium data for the ternary systems of dichloromethane (DCM) + methanol + ionic liquids (ILs) were measured at a constant pressure of 101.3 kPa using a modified Othmer and they were also amended and correlated using the NRTL equation and the results corresponded closely to the original data. The ILs used were 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim][BF 4 ]), 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([Hmim][NTf 2 ]) and 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([Bmim][NTf 2 ]). The results indicated that the addition of ILs had an outstanding effect on the azeotropic system and [Bmim][BF 4 ] and [Hmim][NTf 2 ] could remove the azeotropic point with the mole fraction of 0.109 and 0.162, respectively, which means they could break the azeotropic phenomenon of DCM + methanol. The influence of concentration and kind of ILs was also discussed in this work.

A ring-shaped plasmonic nanostructure is established for realizing the plasmonic field enhancement and focusing through a radial vector beam incidence. The plasmonic light field of the proposed nanostructure is simulated by finite-difference time-domain (FDTD). The results show that the obvious plasmonic field enhancement and focusing spot can be observed when a ring-shaped Au nanostructure is placed on the gold layer. Especially, the maximum of intensity ratio for single ring-shaped nanostructure can reach up to 41, the minimum of the full width at half maximum (FWHM) of focusing spot closes to 60 nm, and spot size beyond the diffraction limit is as small as 0.19λ0. Moreover, the plasmonic field enhancement and focusing can not be realized in the cases of linear polarization, circular polarization, and angular vector polarization incidences. What’s more, the double ring-shaped nanostructure can further develop the intensity ratio to 109 caused by the interference enhancement of surface plasmons. These research results may pave the way for designing the ultra-strong plasmonic field and plasmonic focusing devices.

Isobaric vapor-liquid equilibrium data for the ternary systems of methanol + methyl ethyl ketone (MEK) + 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([BMIM][NTf 2 ]) and methanol + MEK + 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([HMIM][NTf 2 ]) have been measured at 101.3 kPa using a modified Othmer still. The data obtained were correlated using NRTL model and fitted in well with it. The results showed that the addition of ionic liquids (ILs) into the azeotropic system caused a significant salting-in effect on MEK, thus increased the relative volatility of methanol to MEK and broke the azeotrope. And [HMIM][NTf 2 ] has a stronger effect than [BMIM][NTf 2 ]. The elimination of azeotropic phenomenon could be achieved when the mole fraction of ILs in the liquid phase was 0.05 (about 0.40 in mass fraction) or more. The effect of the ILs in this study was compared with that of some other ILs.

We investigate plasmon-induced transparency (PIT) and sensing characteristics in a simple graphene metamaterial through the finite-different time-domain (FDTD) simulation. The results indicate that PIT is caused by the destructive interference between two plasmonic modes in the crossed graphene structure. To effectively and dynamically tune the transmission spectrum of PIT, we can change positional parameters of vertical graphene sheet, and Fermi level, and polarization angle of plane-polarized light, respectively. In particular, when monolayer graphene is changed into two layers, single PIT transparent window splits into double induced transparent windows, and double PIT can also be dynamically tuned by the height h. Further, we also find that the sensitivity can reach up to 1.71345 THz/RIU, and figure of merit(FOM) can reach up to 6.998. The results may provide a new foundation for manufacturing a low-power, ultra-fast response, dynamically adjustable micro-nano sensor in terahertz.

We investigated the isobaric vapor-liquid equilibria (VLE) of the binary system methanol + tetrahydrofuran (THF), the ternary system methanol + THF + 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([BMIM][NTf2]), as well as methanol + THF + 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([HMIM][NTf2]) in a modified Othmer still. The results indicated that the ionic liquids ([BMIM][NTf2] and [HMIM][NTf2]) produced a consistent salting-in effect of THF, resulting in the incremental relative volatility of methanol to THF. The experimental data were correlated using the e-NRTL model, and the parameters were obtained with a good consistency. The ionic liquids even eliminated the azeotropic phenomenon when the mole ratio of [BMIM][NTf2] was up to 0.173 and [HMIM][NTf2] up to 0.128 as calculated by the e-NRTL model. [HMIM][NTf2] had a stronger effect on the separation of azeotropic mixtures than [BMIM][NTf2] did.

The automated discovery of physical laws from discrete noisy data is significant for evaluating the response, stability, and reliability of dynamic systems. In contract to the existing work on the discovery of differential laws, this paper presents a data-driven method to discover the variational laws of physical systems. The effectiveness and robustness to measurement noise are demonstrated with five physical cases. Two features of variational laws, the compact form and holistic viewpoint, lead to two intrinsic advantages in the data-driven discovery of variational laws, namely, reduced data requirement and robustness to noise. The presented data-driven method can be applied to discover variational laws in real time for physical fields or more complicated social sciences, with or without prior knowledge.

We study spectral responses in a bright-dark mode ellipse-shaped resonators coupled waveguide. The results show that the plasmon-induced transparency (PIT) can be observed in the ellipse-shaped resonators coupled waveguide, and the symmetric line shape at the PIT window can be tuned by the radii of the long axis in ellipse-shaped resonators, the coupling distance, and the symmetry broken degree. Interestingly, the radii of the long axis for the bright mode and dark mode have opposite effect on the spectra of PIT. Our research results may pave the way for the understanding and tuning of PIT.

River ice monitoring is of great significance for river management, ship navigation and ice hazard forecasting in cold-regions. Accurate ice segmentation is one most important pieces of technology in ice monitoring research. It can provide the prerequisite information for the calculation of ice cover density, drift ice speed, ice cover distribution, change detection and so on. Unmanned aerial vehicle (UAV) aerial photography has the advantages of higher spatial and temporal resolution. As UAV technology has become more popular and cheaper, it has been widely used in ice monitoring. So, we focused on river ice segmentation based on UAV remote sensing images. In this study, the NWPU_YRCC dataset was built for river ice segmentation, in which all images were captured by different UAVs in the region of the Yellow River, the most difficult river to manage in the world. To the best of our knowledge, this is the first public UAV image dataset for river ice segmentation. Meanwhile, a semantic segmentation deep convolution neural network by fusing positional and channel-wise attentive features is proposed for river ice semantic segmentation, named ICENET. Experiments demonstrated that the proposed ICENET outperforms the state-of-the-art methods, achieving a superior result on the NWPU_YRCC dataset.

Many scholars have conducted in-depth analysis on relevant factors that affect the accuracy of jet dispensing. However, research on the influence of needle impact velocity on jetting performance is limited. Thus, a piezoelectric needle-collision dispenser for micro-droplet jetting is designed in this study, and the influence of the needle impact velocity on jetting effect is deeply analyzed. Initially, the principle of droplet formation and injection is analyzed by Fluent simulation. Thereafter, the mathematical model of the droplet velocity in the nozzle orifice is derived, and the influence of the needle impact velocity on the jetting performance is simulated and analyzed. Results show that the needle impact velocity has an influence on the jetting effect. A prototype of the jetting dispenser is subsequently fabricated, and the needle impact velocity is tested with laser micrometer. The relationship between the needle impact velocity and droplet weight and its corresponding ejected effect are obtained through experimental research. Finally, a UV glue with viscosity of 5,000 cps can be ejected with a minimum average diameter of 272.1 μm by using a needle with a radius of 0.5 mm, a nozzle with a diameter of 50 μm, a taper angle of 90°, a supply pressure of 0.2 Mpa, and a needle impact velocity of 0.13 m/s. The variation of the droplet diameter is within ±2.5%.