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ABSTRACT The phase‐shifted full‐bridge (PSFB) converter has been widely used in DC/DC converters due to its soft‐switching characteristics. However, it still has many drawbacks. In order to solve the shortcomings of the PSFB converter, such as limited soft‐switching range, high loss of duty cycle, and high oscillating voltage of the secondary rectifier, a PSFB converter based on parallel variable inductor and series blocking capacitor is proposed in this study. A wide range of soft switching, low rectifier oscillation voltage, and no duty cycle loss can be realized by the auxiliary current‐controlled variable inductor and reasonable blocking capacitor design. In this study, the mechanism of soft switching and suppression of oscillation is discussed and some of the designs are given. Finally, the experimental results of a 200 W/50 kHz prototype are constructed in the laboratory to verify the feasibility and effectiveness of the proposed converter. [ABSTRACT FROM AUTHOR]

The rational design of a semiconductor heterostructure plays a crucial role in achieving high-performance photoelectrochemical (PEC) applications, such as photodetectors and water splitting due to the diverse functions of the heterointerface in light absorption, corrosion protection, and carrier transportation. Herein, we propose an approach by fully attaching Bi2S3 nanoparticles onto Bi2MoO6 nanorods to fabricate a photoanode for efficient self-powered PEC photodetection and water splitting. This photoanode exhibits remarkable responsivity (11.50 mA/W), rapid response time (200 μs), excellent photon-to-electron conversion efficiency (32.02%), and long-term stability (30,000 s) even without an external bias voltage. These enhancements can be attributed to effective charge separation, unique nanostructural morphology, and an enhanced light capture ability. Leveraging these advantages, the Bi2S3/Bi2MoO6 heterostructure demonstrates an exceptionally high, stable, and bias-free PEC hydrogen evolution rate of 418.95 μmol/cm2/h, surpassing that of both pure Bi2S3 and Bi2MoO6 by factors of 249.38 and 55.38, respectively. Furthermore, compared to previously reported Bi2MoO6-related heterostructures, the Bi2S3/Bi2MoO6 heterostructure exhibits superior PEC catalytic performance. [ABSTRACT FROM AUTHOR]

To solve the problem of testing the sensitivity under electromagnetic pulse radiation for a hot bridge wire electro-explosive device (EED), this paper simulated and analyzed the correlation between the critical ignition current under steady and pulse excitation. The simulation results showed that, under single pulse excitation, the critical ignition current of the EED decreases with the increase in the pulse width, and the variation law can be divided into three pieces: adiabatic, transition, and constant; while under pulse train excitation, due to the thermal cumulative effect, the critical ignition current is related to both material properties and excitation parameters. By analyzing the simulation results and considering the thermal ignition theory, the mathematical model of the critical ignition current under pulse excitation was established, and the mathematical model showed that under pulse train excitation, the critical ignition current is relevant not only to the single pulse excitation critical ignition current, pulse period, and duty cycle, but also to the ratio of single pulse and steady excitation critical ignition current and the thermal time constant. It was verified that the errors between the theoretical values obtained from the mathematical model and the results obtained from the simulation were within 2.5%. [ABSTRACT FROM AUTHOR]

Abstract In light of the complex and dynamic mechanical properties of evolving weak strata in open-pit mines, and the consequent difficulty of determining their mechanical parameters, this study uses the ultimate balance theory, along with the back analysis method combined with monitoring data on field displacement, to carry out parameter inversion using the FLAC3D numerical simulation software. The edge slope of a working pit of the Weijiamao open-pit mine was used as research object to this end. As the results obtained by the constitutive model were consistent with the field monitoring data, the evolving weak strata in the slope and the position of the landslide in the mine could be obtained. The landslide was directed northeast. The mechanism of the edge slope of the working pit was identified as unloading shear failure, and the feasibility of the method of parameter inversion was verified. The internal friction angle ϕ and cohesion C of evolving weak strata in the slope of the open-pit mine were also obtained, where this compensated for the deficiency of laboratory tests and enabled the transformation from qualitative to quantitative analysis. This can provide a reliable basis for the safe operation of open-pit mines.

The mining sequence affects the safe and efficient production of mines and the development and economic benefits of mining enterprises.In order to solve the problem of mining sequence during the fault-subsiding area of Heidaigou open-pit mine, three mining methods are proposed based on the coal and rock occurrence conditions, mine production status and equipment types.The evaluation indicators related to the program from the aspects of economy, technology and safety and used the three-dimensional modeling and simulated mining technology, qualitative and quantitative combination to determine the values of each parameter.Finally, The AHP-ideal point method was used to establish a comprehensive evaluation index system model to determine the optimal mining plan.

In order to solve the measurement problem of the production capacity of the dragline, a prediction method based on gray correlation combined with GA-BP neural network is proposed.The gray correlation analysis is carried out on the 12 influencing factors affecting the production capacity of the dragline, and the actual working hours, the out rate, the effective casting blast amount, and effective throw-out rate are selected.Four influencing factors greater than 0.7 were used as input variables and the monthly production capacity of the dragline was used as the output variable to establish GA-BP neural network and BP neural network prediction model.The results show that the maximum relative error of GA-BP neural network is 7.525%, the average relative error is 3.52%, the average error variance is 0.0156, and the number of iterations is 18 times.The performance is better than the conventional BP neural network.The GA-BP neural network model provides better and more accurate generalization performance for the production capacity of the dragline, and provides a more effective method for predicting the production capacity of the dragline.

In view of uncertainty of comprehensive evaluation index of security risks investigation and govern ability of coal mine, a set pair analysis and evaluation model was established. The model determines evaluation index system from two aspects of personnel factors and govern factors, taking positive and negative, similarity and dissimilarity connection degree into account to obtain a comprehensive connection degree, so as to realize quantitative evaluation of security risks investigation and govern ability of coal mine. The result of case analysis shows that the proposed model can reasonably evaluate security risks investigation and govern ability of coal mine, and the result is in line with the actual situation.

Aiming at the phenomenon that the satellite navigation system loses its positioning caused by electromagnetic radiation, an effect evaluation model of electromagnetic radiation noise based on interference mechanism analysis is established. The effect experiment and the analytical evaluation on the navigation receiver are performed. In order to solve the problem that the sensitivity data of the navigation receiver is difficult to be accurately measured due to weak working signals in the environment to be evaluated, two-point calibration is carried out on sensitivity data by using the working frequency point and a relatively stable frequency point of out-of-band. The effects index of both random noise and single-frequency compound noise is greater than 1 after calibration. The maximum error is 1.8 dB, which is conformed to the theoretical analysis of the effects evaluation model and is consistent with the experimental phenomenon. The results show that the proposed effect evaluation model of electromagnetic radiation noise can be used for in-band and out-of-band noise interference effects evaluation simultaneously, while the proposed two-point calibration method is of great significance to improve the effects evaluation accuracy of tested equipment with weak working signals. [ABSTRACT FROM AUTHOR]