摘要：In the generalized continuum mechanics(GCM)theory framework,asymmetric wave equations encompass the characteristic scale parameters of the medium,accounting for microstructure *** study integrates two theoretical branches of the GCM,the modified couple stress theory(M-CST)and the one-parameter second-strain-gradient theory,to form a novel asymmetric wave equation in a unified *** modeling of the asymmetric wave equation in a unified framework accurately describes subsurface structures with vital implications for subsequent seismic wave inversion and imaging ***,employing finite-difference(FD)methods for numerical modeling may introduce numerical dispersion,adversely affecting the accuracy of numerical *** design of an optimal FD operator is crucial for enhancing the accuracy of numerical modeling and emphasizing the scale ***,this study devises a hybrid scheme called the dung beetle optimization(DBO)algorithm with a simulated annealing(SA)algorithm,denoted as the SA-based hybrid DBO(SDBO)*** FD operator optimization method under the SDBO algorithm was developed and applied to the numerical modeling of asymmetric wave equations in a unified *** the DBO and SA algorithms mitigates the risk of convergence to a local *** numerical dispersion outcomes underscore that the proposed SDBO algorithm yields FD operators with precision errors constrained to 0.5‱while encompassing a broader spectrum *** result confirms the efficacy of the SDBO ***,the numerical modeling results demonstrate that the new FD method based on the SDBO algorithm effectively suppresses numerical dispersion and enhances the accuracy of elastic wave numerical modeling,thereby accentuating scale *** result is significant for extracting wavefield perturbations induced by complex microstructures in the medium and the analysis of scale effects.

摘要：The existing methods for extracting the arrival time and amplitude of ultrasonic echo cannot eff ectively avoid the local interference of ultrasonic signals while drilling,which leads to poor accuracy of the echo arrival time and amplitude extracted by an ultrasonic imaging logging-while-drilling *** this study,a demodulation algorithm is used to preprocess the ultrasonic simulation signals while drilling,and we design a backpropagation neural network model to fit the relationship between the waveform data and time and *** ultrasonic imaging logging model is established,and the finite element simulation software is used for forward *** response under diff erent measurement conditions is simulated by changing the model parameters,which are used as the input layer of the neural network model;The ultrasonic echo signal is considered as a low-frequency signal modulated by a high-frequency carrier signal,and a low-pass fi lter is designed to remove the high-frequency signal and obtain the low-frequency envelope *** the amplitude of the envelope signal and its corresponding time are extracted as an output layer of the neural network *** comparing the application eff ects of the various training methods,we fi nd that the conjugate gradient descent method is the most suitable method for solving the neural network *** performance of the neural network model is tested using 11 groups of simulation test data,which verify the eff ectiveness of the model and lay the foundation for further practical application.

摘要：Heterostructured photocatalysts provide an effective way to achieve enhanced photocatalytic performances through efficient charge *** both wide-and narrow-band-gap photocatalysts have been widely investigated,the charge separation and transfer mechanism at the contacting interface of the two has not been fully ***,a novel SrTiO3/BiOI(STB)heterostructured photocatalyst was successfully fabricated by using a facile *** heterostructure in the photocatalyst extends the photoabsorption to the visible light range,and thus,high photocatalytic NO removal performance can be achieved under visible light irradiation.A combination of experimental and theoretical evidences indicated that the photogenerated electrons from the BiOI semiconductor can directly transfer to the SrTiO3 surface through a preformed electron delivery *** electron transfer was expected between the SrTiO3 and BiOI surfaces under light irradiation,and leads to efficient ROS generation and thus a high NO conversion ***,in situ diffused reflectance infrared Fourier transform spectroscopy revealed that STB can better inhibit the accumulation of the toxic intermediate NO2 and catalyze the NO oxidation more *** work presents a new insight into the mechanism of the interfacial charge separation in heterostructures and provides a simple strategy to promote the photocatalytic technology for efficient and safe air purification.

摘要：Constructing a suitable heterojunction photocatalytic system from two photocatalytic materials is an efficient approach for designing extremely efficient photocatalysts for a broader range of environmental,medical,and energy ***,the construction of a step-scheme heterostructure system(hereafter called the S-scheme)has received widespread attention in the photocatalytic field due to its ability to achieve efficient photogenerated carrier separation and obtain strong photo-redox ***,a novel S-scheme heterojunction system consisting of 2D O-doped g-C_(3)N_(4)(OCN)nanosheets and 3D N-doped Nb_(2)O_(5)/C(N-NBO/C)nanoflowers is constructed via ultrasonication and vigorous agitation technique followed by heat treatment for the photocatalytic degradation of Rhodamine B(RhB).Detailed characterization and decomposition behaviour of RhB showed that the fabricated material shows excellent photocatalytic efficiency and stability towards RhB photodegradation under visible-light *** enhanced performance could be attributed to the following factors:fast charge transfer,highly-efficient charge separation,extended lifetime of photoinduced charge carriers,and the high redox capability of the photoinduced charges in the S-scheme *** trapping experiment conditions and electron paramagnetic resonance provide clear evidence of the S-scheme photogenerated charge transfer path,meanwhile,the RhB mineralization degradation pathway was also investigated using *** study presents an approach to constructing Nb_(2)O_(5)-based S-scheme heterojunctions for photocatalytic applications.