Search

From the outbreak on December 19, 2019, to the current normalization of the epidemic, people stay at home for entertainment. The popularity of short videos has increased dramatically, and the use of Douyin has skyrocketed. This paper analysed the development strategy of Douyin, and further explored the power of brand equity on Douyin use intention by applying the theoretical knowledge and qualitative analysis of the influence of brand equity on purchase intention and the SWOT analysis method. SWOT analysis was used to analyse the impact of brand equity on the willingness to use Douyin, and the conclusion was drawn that in terms of SO, the intuitive and eye-catching the brand image of Douyin and the positive development of brand virtual character image improved the willingness to use. In WT, Douyin’s negative brand association and high-end brand positioning reduced the desire to use. Therefore, Douyin needed to improve in purifying the network environment and enhancing user participation in third - and fourth-tier cities.

Purpose To compare the effect of traditional conjunctival sac swab sampling (A) with aerosolization ocular surface microorganism sampling (B),a novel microbial sampling method, in detecting ocular microbial infection. Methods The study included 61 participants (122 eyes) enrolled at the Eye Hospital, Wenzhou Medical University from December, 2021 to March, 2023. Each eye of the participants underwent sampling first with method A then B.Before aerosolization sampling, the air environment was disinfected and sampled as blank air control sample. Subsequently, the air pulses impinging the ocular surface causes dehiscence of the tear film covering the ocular surface and aerosols are formed.The microorganisms from the ocular surface attach to the aerosols generated as aerosolization ocular surface microorganism and be sampled as subject sample by bio-aerosol sampler.The samples were collected and incubated at 25℃ for 3–5 days and 37℃ for 24–48 h.The colonies were counted and identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Results The accuracy in Group B was higher than that in Group A (45.8% vs. 38.3%, P = 0.289). There was a slight level of agreement between the results from both the sampling methods (k = 0.031, P = 0.730). The sensitivity in Group B was higher than that in Group A (57.1% vs. 35.7%, P = 0.453). The specificity results in Group B was higher than that in Group A (44.3% vs. 38.7%, P = 0.480). There were 12 and 37 types of microbes detected in Groups A and B, respectively. Conclusions Compared with traditional swab sampling, the novel aerosolization sampling method shows higher accuracy and more comprehensive detection of microbes; however, it cannot completely replace swab sampling. The novel method can be a novel conducive strategy and supplement swab sampling to auxiliary diagnose ocular surface infection.

ObjectiveOur study aims to evaluate the association between heart rate variability (HRV) and short and long-term prognosis in patients admitted to intensive care unit (ICU).Methods and ResultsAdult patients continuously monitored for over 24h in ICUs from the MIMIC-IV Waveform Database were recruited in our study. Twenty HRV-related variables (8 time-domain, 6 frequency-domain; and 6 nonlinear variables) were calculated based on RR intervals. The association between HRV and 30-day all-cause mortality was assessed. Ninety-three patients met the inclusion criteria and were classified into 30-day survivor group and non-survivor groups based on their survival status. The 30-day all-cause mortality rate was 17.2%. NN50 and pNN50 were both significantly higher in non-survivors compared to survivors, whereas the rest of the time-domain, frequency domain and non-linear HRV parameters did not differ significantly between the two groups (allP>0.05). In addition, at 180 days after admission, non-survivors had significantly higher levels of NN50 and rMSSD than the survivors. However, NN50 was not an independent predictor of 30-day all-cause mortality in patients by multivariate COX regression analysis (HR, 1.0; 95% CI, 1.000 - 1.001;P=0.594). The Area Under the Curve (AUC), cut-off value, sensitivity and specificity of NN50 for predicting 30-day all-cause mortality using ROC were 0.67, 799, 0.813 and 0.584, respectively. Plotting Kaplan-Meier analysis using this cut-off value showed that patients with high NN50 had considerably greater 30-day all-cause mortality than those with low NN50 (P< 0.001).ConclusionNN50 and pNN50 are associated with elevated 30-day all-cause mortality in ICU patients but are not independent predictors of all-cause mortality using multivariate COX regression analysis.

Stability of explicit FDTD algorithm is limited by the established relationship which results in computation duration unacceptable in certain circumstances. To enhance the development of FDTD algorithm, unconditionally stable scheme is implemented to overcome such problem, especially for the open region simulation. Here, for bandpass simulation of anisotropic magnetized ferrite material, complex envelope (CE) method and its modified scheme are employed into the implementation. Generally speaking, the proposed scheme incorporates the alternating direction implicit (ADI) with the CE method during the simulation obtaining the bandpass ADI form in perfectly matched layer (PML) regions. Meanwhile, the proposed scheme establishes the bandpass calculation method of constitutive relationship in ferrite material regions. Such method can also be employed into the unmagnetized isotropic materials and other media. Through ferrite slab model and ferrite waveguide structure, accuracy, absorption and efficiency are demonstrated in the bandpass open region simulation numerically. The proposed scheme can not only benefit an impressive performance but also maintain both of stability and accuracy with decrement of iteration steps which can be proved to be an unconditionally stable implementation. Meanwhile, it also alleviates time increment problem within implicit schemes of small time steps. Thus, benefits of the proposed scheme can be summarized from the following categories: 1) Enhanced absorption and efficiency for the ADI procedure. 2) Decrement of duration with a small time step. 3) Bandpass form inside the magnetized ferrite material. 4) Extensively employment in different kinds of materials.

In order to reduce the work intensity of traditional medical staff on patient patrol and timely understand the status of various indicators of patients, a set of patient intelligent monitoring system which based on Internet of things and cloud platform is designed. This study uses the internet of things technology to monitor the patient's heartbeat, pulse, ballistocardiography, body position, whether out of bed and sleep quality. The data is transmitted through optical fiber sensing technology and uploaded to the cloud platform to understand the patient's situation in real time. The results show that the system has stable performance and can ensure the real-time and accuracy of medical information. Meeting the needs of ward front-line management, not only reduce the workload of nurses, but also improve work efficiency. It is great significance to ward management and the development of hospital information construction.

A theoretical model considering the interface shear deformation is developed to investigate the bending properties of graphene substrates coated with nano-film. This paper presents a closed-form solution for predicting the bending properties of graphene substrates coated with nano-film. Based on the proposed model, we investigate the effects of the interface shear stiffness and the boundary conditions on the bending properties of graphene substrates. A parameter study was carried out analyzing the mechanical behaviors of the graphene substrates. As a result, a parametric study is conducted to show the importance of interface shear transfer mechanisms. The interface shear stress and the deflection of the graphene substrates are largely affected by the interface shear stiffness, the concentrated load position and the boundary conditions of loading. Restraint against bending deflection of graphene nanoribbons coated with nanofilm under the lateral load can be easily investigated using the present theory. The theoretical investigation on the bending behavior provides a useful reference for understanding the interfaces shear deformation in graphene substrates.

Due to the unique nonreciprocal characteristic, ferrite exhibits anisotropic behaviour in electric performance. Owing to such special phenomenon, it is difficult to efficiently analyse and simulate...

In the sub-millimeter-wave band, the wave is transmitted between two aperture antennas merely in the near-field region because of high working frequency and large space transmission loss. The antenna gain defined in the far-field region is no longer applicable under certain circumstance. Therefore, the near-field gain, one of the most important parameters of the sub-millimeter-wave antenna, should be defined. Based on the transmission equation and near-field transmission efficiency formulation, the near-field gain expression for the aperture antenna is proposed. The proposed expression can be applied to the entire radiation area, including not only the near field but also the far field. From the perspective of the theoretical derivation and numerical simulation, the results of the near-field gain for the aperture antenna are obtained in the sub-millimeter-wave band. Through a comparison with the published research, it can be concluded that the proposed expression is reasonable, indicating the theoretical establishment of the near-field gain and its potential application to the sub-millimeter-wave antenna design and sub-millimeter-wave radar theory.

For bandpass simulation of nonreciprocal devices with fine and complex structures, hybrid implicit–explicit (HIE) perfectly matched layer (PML) which is incorporated with the higher order concept and complex envelope (CE) method is proposed in finite-difference time-domain (FDTD) lattice. The proposed implementation shows advantages in terms of efficiency, accuracy, and absorption. The effectiveness is demonstrated through the simulation and measurement of ferrite circulator. Through numerical results, the proposed scheme can obtain considerable efficiency and enhanced absorption. From the measurement results, it can be seen that the proposed scheme impacts entire performance in bandpass nonreciprocal simulation.

Based upon the approximate Crank–Nicolson (CN) algorithms and the higher order (HO) concept, unconditionally stable perfectly matched layer (PML) implementations are proposed for electromagnetic problems in the finite-difference time-domain (FDTD) lattice. The approximate CN algorithms include the CN direct-splitting (CNDS) and CN approximate-factorization-splitting (CNAFS). The proposed schemes take advantage of the approximate CN algorithms in terms of eliminating the Courant–Friedrichs–Levy stability condition and maintaining the computational accuracy. By introducing the HO concept to the PML formulation, the absorbing performance can be enhanced during the simulation. Furthermore, to cope with the existence of half-time-step problems in simulating the anisotropic magnetized plasma, a modified ADE method is proposed at the integer time step. Thus, the modified ADE method can be directly employed in the approximate CN algorithms. Numerical examples and experiments are carried out to demonstrate the effectiveness, efficiency, and performance. Through the results, it can be observed that the computational efficiency and absorbing performance can be significantly improved. Meanwhile, it can be concluded that the CNAFS-PML and CNDS-PML algorithms show higher accuracy and considerable efficiency, respectively, when the time step surpasses far beyond the CFL condition.

By incorporating the higher-order concept with the perfectly matched later (PML) scheme, unconditionally stable approximate Crank–Nicolson algorithm is proposed for plasma simulation in open region problems. More precisely, the proposed implementation is based on the CN Direct-Splitting (CNDS) procedure for the finite-difference time-domain (FDTD) unmagnetized plasma simulation. The unmagnetized plasma can be regarded as frequency-dependent media which can be calculated by the piecewise linear recursive convolution (PLRC) method. The proposed implementation shows the advantages of higher-order concept, CNDS procedure, and PLRC method in terms of improved absorbing performance, enhanced computational efficiency, and outstanding calculation accuracy. Numerical examples are introduced to indicate the effectiveness and efficiency. It can be concluded from results that the proposed scheme shows considerable efficiency, accuracy, absorption, and unconditional stability.

People spend about 5-8 hours per day on phones, causing circadian disruption and eye fatigue, thus raising a great need for comfort and health. Most phones have eye protection modes, claiming a potential eye protection effect. To examine the effectiveness, we investigated the color quality, namely gamut area and just noticeable color difference (JNCD), and circadian effect, namely equivalent melanopic lux (EML) and melanopic daylight efficacy ratio (MDER), characteristics of two smartphones: iPhone 13 and HUAWEI P30, in normal and eye protection mode. The results show that the circadian effect is inversely proportional to color quality when the iPhone 13 and HUAWEI P30 changed from normal to eye protection mode. The gamut area changed from 102.51% to 82.5% sRGB and 100.36% to 84.55% sRGB, respectively. The EML and MDER decreased by 13 and 15, and, 0.50 and 0.38, respectively, affected by the eye protection mode and screen luminance. The EML and JNCD results in different modes show that the eye protection mode benefits the nighttime circadian effect at the cost of the image quality. This study provides a way to precisely assess the image quality and circadian effect of displays and elucidates the tradeoff relationship between them.

By incorporating higher order formulation with perfectly matched layer (PML) implementation, unconditionally stable computationally efficient locally one-dimensional (LOD) algorithm with improved absorption is proposed for simulating ground penetrating radar and its open region problems in finite-difference time-domain (FDTD) algorithm. To take advantages of these methods, the proposed implementation shows characteristics of maintaining considerable accuracy, enhancing computational efficiency and improving the entire absorption. These above-mentioned advantages are illustrated through the ground penetrating radar related problem in open regions. It can be concluded from the calculation results that the proposal shows advantages of higher order formulation, PML implementation and LOD procedure which are efficient in remarkable accuracy, considerable efficiency and improved absorption with increment of CFLNs. Meanwhile, the simulation results also indicate that the proposal is an unconditionally stable procedure with the dissatisfaction of Courant-Friedrichs-Levy stability condition.

For the simulation of gyrotropic plasma structure with fine geometry details along a single direction in open regions, the hybrid implicit-explicit (HIE) algorithm with improved absorbing boundary condition is modified based on the finite-difference time-domain (FDTD) algorithm. More precisely, incorporating the perfectly matched layer (PML) formulation, the higher order concept and the HIE procedure, the proposed implementation shows its significant superiority in terms of efficiency, accuracy and absorption. To simulate the unique anisotropic characteristic inside the gyrotropic plasma regions, the bilinear transform (BT) method is employed during the calculation. The effectiveness can be further demonstrated theoretically and numerically. Through the results, it can be concluded that the proposed scheme exhibits remarkable behaviors in the gyrotropic plasma open region problems. It can not only obtain considerable accuracy compared with the theoretical solution but also receive better absorption and efficiency compared with the published work. In addition, the results also indicate that the proposed scheme can maintain the stability of the algorithm with dissatisfaction of the Courant-Friedrichs-Levy condition between time step and mesh size.

A numerical approach has been proposed to identify bands for optimally estimating the concentration of three types of viable chromophores within biological tissue. The bands are determined according to the condition number of absorption matrix associated with the attenuation coefficients of chromophores. The effectiveness of different sets of selected band combination was verified by using the spectral reflectance images of skin tissue acquired from standard forearm vascular occlusion tests via a spectroradiometer. Experimental results demonstrated that the concentration of chromophores within skin tissue could be estimated correctly and robustly only when the bands were deliberately selected.

By incorporating the complex envelope (CE) method and the higher order concept, unconditionally stable perfectly matched layer (PML) is proposed based on the Crank–Nicolson approximate-factorization-splitting (CNAFS) algorithm to simulate the bandpass problems in finite-difference time-domain lattice. The proposed algorithm has the advantages of the CNAFS algorithm, higher order PML concept, and CE method in terms of improving efficiency, enhancing absorbing performance, and simulating bandpass problems. A patched antenna model is carried to investigate effectiveness and efficiency.

Based on the alternating direction implicit (ADI) procedure, the complex envelope (CE) method, and the higher order (HO) concept, an unconditionally stable performance-enhanced convolutional perfectly matched layer (CPML) is proposed to efficiently simulate bandpass electromagnetic (EM) devices and signals in the finite-difference time-domain (FDTD) lattice. Through the numerical example, the proposed scheme shows the advantages of the unconditionally stable ADI procedure, HO-CPML scheme, and CE method in terms of absorbing performance, computational efficiency, and bandpass EM simulation.

With the unique flexibility or ductility, and efficient low-cost manufacturing process, flexible electronic devices have attracted a growing interest in scientific research and industry with applications in wearable electronic devices, stretchable antennas, flexible displays, and energy devices. Flexible conductive film (FCF), which functionalizes in building connections between different components of the devices, is key constitutions in flexible devices. We prepared the flexible conductive film with a diameter of approximately 60 nm and a length of 20 μm of silver nanowires (AgNWs) as the fillers and thermopolyurethane (TPU) as the matrix by solution blending and tape casting method. Further, self-made fluorinated decyl polyhedral oligomeric silsesquioxane (F-POSS) as hydrophobic layer was deposited on the AgNWs-TPU conductive film by immersing method. We systematically studied the properties of electronic conductivity, electrothermal response and infrared radiation (IR) thermal response performances, and superhydrophobic performance of AgNWs-TPU conductive films. The experimental results reveal that as the mass content of AgNWs reaches 30 wt%, the film displays good conductivity, and the resistivity of the film with 40 wt% AgNWs is 0.07 Ω·mm. AgNWs-TPU conductive film has good electrothermal response and IR thermal response performances. The water contact angle of the AgNWs-TPU conductive film with superhydrophobic layer reaches 155.29° ± 1.03 and superhydrophobic AgNWs-TPU conductive film slightly improves the reliability and tensile strength of the AgNWs-TPU conductive film. Our experimental results indicate that the superhydrophobic flexible conductive films prepared in this experiment can be applied to wearable flexible devices.

Conversion of syngas to useful chemicals is a hot topic and the supported Co catalyst plays a very important role in this process. To prevent the aggregation of Co crystalline, it is suggested to c...

In order to efficiently simulate the symmetrical structures in the cylindrical coordinate system, the implementation of the complex frequency-shifted perfectly matched layer based on the body of revolution finite-difference time-domain algorithm is proposed for analysing the magnetised ferrite microwave structures. To improve the computational efficiency in the magnetised ferrite domain compared with the existing calculation methods, the bilinear Z-transform for the simulation of the dispersion relationship of the magnetised ferrite is proposed. The proposed implementations can not only improve the computational efficiency but also obtain a considerable absorbing performance. Numerical examples based on the magnetised ferrite microwave structures are carried out to demonstrate the effectiveness and efficiency of the proposed formulations.

An unconditionally stable and efficient higher order complex frequency-shifted perfectly matched layer (CFS-PML) based on the Crank–Nicolson-approximate-decoupling (CNAD) algorithm is proposed for truncating the finite-difference time-domain (FDTD) computational domain filled with the left-handed materials (LHMs). The proposed higher order CFS-PML is implemented by the bilinear transform (BT) approach and the LHMs are solved by the trapezoidal recursive convolution (TRC) method. A numerical example is provided to validate the effectiveness of the proposed implementation. The results show that the proposed CFS-PML not only has better absorbing performance compared with the first-order CNAD CFS-PML and the alternating-direction-implicit (ADI) CFS-PML but also takes advantage of the unconditional stability of the original Crank–Nicolson algorithm.

Active echo cancellation is an efficient method for reducing the target detected probability. The radar cross section (RCS) of the target detected by radar after using the active echo cancellation method is defined as the active radar cross section (ARCS). The ARCS concept, which may be used to evaluate reflection of the target under the effect of multiple antennas, is employed to design and achieve echo cancellation. In this paper, numerical simulation for active echo cancellation using antennas is designed. The direction of the radiation source is obtained by means of dual antenna angle measurement. Active echo cancellation is implemented by adjusting the radiation power and phase of the echo cancellation antenna. By using the proposed dual antenna structure, ARCS in the direction of the object facing the radiation source and its vicinity is significantly reduced. In addition, the effect of antenna position on reflection cancellation is discussed. From these simulation results, we conclude that the proposed method is efficient in reducing the target scattering intensity. Such investigation can be extensively applied into designing active echo cancellation strategies.

Dental caries detection, especially the accurate detection of early caries, facilitates prompt interventions. It is reasonably common to use fluorescence imaging for classification and evaluation of caries, but lacks a quantitative, precise and easy-to-use characterization for practical applications. In this study a quantitative approach for caries stage detection by correlating caries spectral and chromatic features was examined.A 405 nm LED light source was used as the excitation source. A hyperspectral imaging camera is employed to collect 336 spectral data of different caries stages. Four critical intervals for different stages of caries were extracted by fluorescence spectral features. The mapping relationship between caries spectral and chromatic features was established by Fast Formula Fitting (FFF) and Neural Network Fitting (NNF) methods.The 470-780 nm spectral power distribution was proved to be the best matching color waveband guiding the selection of filters in future instrument development. The correlation coefficients for the two fitting methods were 0.990 and 0.999, respectively. Both methods achieved caries stage prediction at the pixel level with high accuracy using color information. The visualization region in the chromaticity diagram was created.This quantitative method enables accurate prediction of caries on the entire tooth surface and facilitates the development of portable and low-cost caries detection instruments.

An unconditionally stable implementation of the higher order complex frequency-shifted (CFS) perfectly matched layer (PML) is proposed for the Crank-Nicolson-approximate-decoupling (CNAD) finite-difference time-domain (FDTD) scheme. The proposed higher order CFS-PML, which is implemented by the auxiliary differential equation (ADE) method, not only has better performance than the first-order PML but also maintains the unconditional stability of the origin Crank-Nicolson (CN) algorithm. The unmagnetised plasma, which can be expressed by the Drude medium and implemented by the piecewise linear recursive convolution (PLRC) method, is truncated by the proposed PML scheme. A numerical example is provided to validate the effectiveness of the proposed formulations.

Most terahertz (THz) radar systems can only work in the near-field region, because the THz source power is limited and the size of the target scattered near field is up to tens of kilometers. Such conditions will result in the conventional radar range equation being unsuitable. Therefore, the near-field radar cross section (RCS) formula is given according to the numerical simulation on different targets. By modifying the parameters in the near field, including the gain of radar antennas and the RCS of targets, the generalized radar range equation is proposed. The THz radar working efficiency in the whole range and the simulation of the near-field RCS simulation model were employed to validate its effectiveness. Through comparison with the radar range equation, it can be concluded that the calculation results of the proposed equation are smaller in the near field, and the outcomes in the far field are identical. The proposed generalized radar range equation can be applied to the whole radiation area including the near field and the far field. Furthermore, more complicated real targets are calculated according to the generalized radar range equation and it can be extended from the submillimeter wave band to a much wider band range. Finally, the near-field radar theory is established, which shows its potential application to the radar cross section estimation in the extremely high frequency and fine design of THz radar systems.

In this paper, the effects of multi-radiators on the electromagnetic scattering characteristics of coated flat plate in half space are investigated. The electromagnetic scattering characterization of coated flat plate are represented by active radar cross section (ARCS) under multi-radiators. Simulations were conducted to research the effect of radar absorbing materials (RAM) and multi-radiators on the electromagnetic scattering characteristics of flat plate in half space. Through the resultants, it can be concluded that the electromagnetic scattering characteristics are significantly influenced by RAM and multi-radiators.