A New Method Applied to the Quadrilateral Membrane Element with Vertex Rigid Rotational Freedom

In order to improve the performance of the membrane element with vertex rigid rotational freedom, a new method to establish the local Cartesian coordinate system and calculate the derivatives of the shape functions with respect to the local coordinates is introduced in this paper. The membrane elements with vertex rigid rotational freedom such as GQ12 and GQ12M based on this new method can achieve higher precision results than traditional methods. The numerical results demonstrate that the elements GQ12 and GQ12M with this new method can provide better membrane elements for flat shell elements. Furthermore, this new method presented in this paper offers a new approach for other membrane elements used in flat shell element to improve the computing accuracy

Successive Vaccination and Difference in Immunity of a Delay SIR Model with a General Incidence Rate

A delay SIR epidemic model with difference in immunity and successive vaccination is proposed to understand their effects on the disease spread. From theorems, it is obtained that the basic reproduction number governs the dynamic behavior of the system. The existence and stability of the possible equilibria are examined in terms of a certain threshold condition about the basic reproduction number. By use of new computational techniques for delay differential equations, we prove that the system is permanent. Our results indicate that the recovery rate and the vaccination rate are two factors for the dynamic behavior of the system. Numerical simulations are carried out to investigate the influence of the key parameters on the spread of the disease, to support the analytical conclusion, and to illustrate possible behavioral scenarios of the model

Successive Vaccination and Difference in Immunity of a Delay SIR Model with a General Incidence Rate

A delay SIR epidemic model with difference in immunity and successive vaccination is proposed to understand their effects on the disease spread. From theorems, it is obtained that the basic reproduction number governs the dynamic behavior of the system. The existence and stability of the possible equilibria are examined in terms of a certain threshold condition about the basic reproduction number. By use of new computational techniques for delay differential equations, we prove that the system is permanent. Our results indicate that the recovery rate and the vaccination rate are two factors for the dynamic behavior of the system. Numerical simulations are carried out to investigate the influence of the key parameters on the spread of the disease, to support the analytical conclusion, and to illustrate possible behavioral scenarios of the model

A complete study of space-time-frequency statistical properties of the 6G pervasive channel model

The sixth generation (6G) pervasive channel model (6GPCM) can characterize channels for all spectra from the sub-6 GHz band to the visible light communication (VLC) band and all scenarios, such as maritime, (ultra-)massive multiple-input multiple-output (MIMO), and industrial Internet of things (IIoT) communication scenarios in 6G wireless systems. The unified channel model can enable us to analyze channel statistical properties in systems using different scales of antenna arrays, different frequency bands, and different scenarios with different movement speeds. In this paper, we conduct a complete study on space-time-frequency (STF) statistical properties of the 6GPCM. Mathematical derivations and simulations are provided, including STF correlation function (STFCF), spatial/temporal/frequency correlation functions, angular/Doppler/delay power spectral densities (PSDs), root mean square (RMS) angular/Doppler/delay spreads, coherence distance/time/bandwidth, stationary distance/time/bandwidth, and level-crossing rates (LCRs)/average fade durations (AFDs) in STF domains. In addition, we classify these statistical properties according to their definitions and then reveal the complex relationships between them and channel model parameters. This work will lay a solid foundation and offer useful guidelines for research on 6G wireless communication systems

Enhancement in Interfacial Adhesion of Ti/Polyetheretherketone by Electrophoretic Deposition of Graphene Oxide

This is the peer reviewed version of the following article: Pan, L., Lv, Y., Nipon, R., Wang, Y., Duan, L., Hu, J., ... & Shi, Y. (2019). Enhancement in Interfacial Adhesion of Ti/Polyetheretherketone by Electrophoretic Deposition of Graphene Oxide. Polymer Composites, 40(S2), E1243-E1251, which has been published in final form at https://doi.org/10.1002/pc.24955. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions.This article discusses about the significance of graphene oxide (GO) deposition on the surface of a titanium plate by electrophoretic deposition (EPD) method to improve the adhesive strength of Ti/polyetheretherketone (PEEK) interfacial adhesive. Firstly, the anodic EPD method was applied to a water dispersion solution of GO, and then the morphology and the properties of titanium plate surface were characterized by scanning electron microscopy and contact angle measurements before and after GO deposition. Furthermore, the changes in the properties of GO after heating at 390°C were characterized by Raman and Fourier transform infrared spectroscopies. According to the results of single lap tensile shear test, the adhesion strength of Ti/PEEK interface after the anodization and deposition of GO was 34.94 MPa, an increase of 29.2% compared with 27.04 MPa of sample with only anodization. Also, the adhesion strengths were 58.1 and 76.5% higher compared with the samples of only GO deposited (22.1 MPa) and pure titanium (19.8 MPa), respectively

Effect of strong time-varying transmission distance on LEO satellite-terrestrial deliveries

In this paper, we investigate the effect of the strong time-varying transmission distance on the performance of the low-earth orbit (LEO) satellite-terrestrial transmission (STT) system. We propose a new analytical framework using finite-state Markov channel (FSMC) model and time discretization method. Moreover, to demonstrate the applications of the proposed framework, the performances of two adaptive transmissions, rate-adaptive transmission (RAT) and power-adaptive transmission (PAT) schemes, are evaluated for the cases when the transmit power or the transmission rate at the LEO satellite is fixed. Closed-form expressions for the throughput, energy efficiency (EE), and delay outage rate (DOR) of the considered systems are derived and verified, which are capable of addressing the capacity, energy efficiency, and outage rate performance of the considered LEO STT scenarios with the proposed analytical framework

Fluidization characteristics and separation performance of mild-hot gas-solid fluidized bed

In recent years, the mild-hot gas-solid fluidized bed had a crucial influence on wet-in-feed sorting when it comes to moist feed (e.g., lignite) because of its expanding sorting range. To explain the favorable sorting effect of the mild-hot gas-solid fluidized bed, the fluidization characteristics (e.g., the pressure drop, density, etc.) was studied under different work conditions. In addition, a high-speed dynamic camera was used in this study to compare the slumping behavior of the magnetite slag at different temperatures. The optimum conditions for coal separation was also studied by Design-Expert software. It was shown that the bed temperature of the fluidized bed has a particular effect on its stability when the bed temperature was below 120 °C, which had a great influence on the separation. Finally, the probable deviation E of the mild-hot gas-solid fluidized bed under optimum operation conditions could be as low as 0.09 g/cm3 which showed the good separation ability

A Study on Evaporation Calculations of Agricultural Reservoirs in Hyper-Arid Areas

Free surface evaporation is an important process in regional water cycles and energy balance. The accurate calculation of free surface evaporation is of great significance for evaluating and managing water resources. In order to improve the accuracy of estimating reservoir evaporation in data-scarce arid regions, the applicability of the energy balance method was assessed to calculate water surface evaporation based on the evaporator and reservoir evaporation experiment. A correlation analysis was used to assess the major meteorological factors that affect water surface temperature to obtain the critical parameters of the machine learning models. The water surface temperature was simulated using five machine learning algorithms, and the accuracy of results was evaluated using the root mean square error (RMSE), correlation coefficient (r), mean absolute error (MAE), and Nash efficiency coefficient (NSE) between observed value and calculated value. The results showed that the correlation coefficient between the evaporation capacity of the evaporator, calculated using the energy balance method and the observed evaporation capacity, was 0.946, and the RMSE was 0.279. The r value between the calculated value of the reservoir evaporation capacity and the observed value was 0.889, and the RMSE was 0.241. The meteorological factors related to the change in water surface temperature were air temperature, air pressure, relative humidity, net radiation and wind speed. The correlation coefficients were 0.554, −0.548, −0.315, −0.227, and 0.141, respectively. The RMSE and MAE values of five models were: RF (0.464 and 0.336), LSSVM (0.468 and 0.340), LSTM (1.567 and 1.186), GA-BP (0.709 and 0.558), and CNN (1.113 and 0.962). In summary, the energy balance method could accurately calculate the evaporation of evaporators and reservoirs in hyper-arid areas. As an important calculation parameter, the water surface temperature is most affected by air temperature, and the RF algorithm was superior to the other algorithms in predicting water surface temperature, and it could be used to predict the missing data. The energy balance model and random forest algorithm can be used to accurately calculate and predict the evaporation from reservoirs in hyper-arid areas, so as to make the rational allocation of reservoir water resources