Exploring the cultivation of innovative talents in mechanical disciplines in the context of the new engineering discipline

With the improvement of China’s economic and technological development level, the concept of “new engineering” has been paid more and more attention. As the main force to promote the development of China’s manufacturing industry, the cultivation of innovative talents of mechanical majors will play a very key role. Based on this, this paper analyzes the current situation of the cultivation of innovative talents in mechanical major. We put forward some effective training strategies, such as the construction of a new talent training model and the establishment of an integrated teaching system

An exploration of project-driven cultivation of students’ innovative ability in college English teaching

Innovation ability is an integral part of students’ comprehensive ability. Compared with students majoring in engineering, students majoring in arts should pay more attention to the improvement of innovation ability in training. This paper expounds the significance of project driven in the cultivation of college students’ innovation ability, introduces the goal of cultivating students’ innovation ability in college English teaching, discusses the implementation path and optimization strategy of the project from three aspects of reading project, writing project and speech project, and explores the talent cultivation mode that conforms to the characteristics of college English teaching and acknowledges the social needs

Structural Dynamic Load and Parameter Identification Based on Dummy Measurements of Displacement

Structural load and parameter identification are the essential contents in the field of structural dynamics, and some studies pay attention to the coupled recognition of uncertain structure parameters as well as unacquainted loads. Gillijns and De Moor presented the Kalman-type filter, which was used in the work for coupled identification as the unabbreviated form of GDF. However, it has been demonstrated that it is unstable for the extended GDF (EGDF) method, drifting in the identified unacquainted loads as well as displacement, just like most previous identification methods based on the least-square algorithm. In order to deal with this unstable issue, this paper applied the dummy measurements of displacements on a position level and modifies the EGDF algorithm using the information integration method about the accelerated measurements with dummy measurements. Numerical example of a truss is used for validating the applicability of the method in the work, and an influence of covariance matrices in dummy displacements is also considered

GEAR FAULT DIAGNOSIS BASED ON THE VMD AND MODULATION SPECTRUM INTENSITY DISTRIBUTION

VMD has better band-pass filtering characteristic, which can non-recursively decomposition a real-valued multi-composition signal into a discrete number of quasi-orthogonal band-limited sub-signals with specific sparsity properties in the spectral. Modulation intensity distribution（MID） combined with VMD is applied to detect second-order cyclostationary components in gear fault diagnosis. Impulsive signatures generally represent the transients in the signals and are often caused by local defect in the gear of rotating machinery. Detecting these signatures is vital for mechanical signal processing and fault diagnosis. The impulsive signatures can be successfully extracted using VMD, meanwhile, Signal-noise can be separated to some extent. It is very useful tool to MID detects modulation components. However, when the analyzed signal contains multiple modulations usually mixed with other harmonic components, visual examination of the spectrum may not be accurate for identification of all carriers together with their modulation signals. Considering the shortcomings of MID in the analysis of multi-harmonic modulation signals, VMD is used as the signal preprocessing before MID analysis. Results of simulation and the experimental analysis have demonstrated the effectiveness of the method

Long-term performance of a continuous box-girder bridge constructed using precast segments with wet ultra-high-performance concrete (UHPC) joints

Although the precast segmental construction (PSC) technique can relieve age-dependent difficulties and accelerate bridge construction as compared to the cast-in-situ construction (CSC) technique for long-span prestressed concrete box-girder bridges (LSPCBB), the ordinary concrete joints between adjacent precast segments are risky. In order to improve the bond strength at the joint interface and enhance structural reliability, ultra-high-performance concrete (UHPC) can be used to fill joints as a new cementitious material with high strength, ductility, and durability. Thus, the effect of the naturally cured UHPC shrinkage and creep on the bridge\u27s long-term performance should be evaluated. The present study numerically investigates the long-term bridge performance constructed by the PSC technique with wet UHPC joints. One cast-in-place segment using the CSC technique is replaced by one precast segment and one cast-in-place UHPC joint using the PSC technique in the bridge model. A creep coefficient equation in an existing code and a shrinkage strain equation fitted from the test data for the UHPC are verified, and an equivalent temperature drop method is used for simulating pretension forces of the prestressing strands in the numerical model. Through comparison with the CSC technique, the technical advantages in reducing long-term deflection, rotation, prestress losses, and improving normal cross-sectional stresses are quantitatively highlighted for the UHPC enhanced PSC bridge

Switching Capacitor Filter with Multiple Functions, Adjustable Bandwidth in the Range of 5 Hz–10 kHz

This article proposes a second-order switch-capacitor filter that integrates low-pass, high-pass, band-pass, band-stop, and all-pass, and achieves flexible bandwidth adjustment of the filter through clock rate and capacitance ratio. The final filter design consists of two completely independent second-order switch-capacitor filter channels, and a 4-order Butterworth low-pass filter is designed through two-stage cascades. The two completely independent second-order switch-capacitor filters are integrated on a single chip and manufactured using the Huahong BCD350GE high-voltage 24 V process. The measurement results indicate that the proposed switch-capacitor filter achieves various functional filtering characteristics and achieves a bandwidth of 5 Hz to 10 kHz. The chip area is 5.1 × 3.1 mm2, powered by a dual power supply of ± 5 V, and the power consumption is 80 mW

Research on Rolling Bearing Fault Diagnosis Using Improved Majorization-Minimization-Based Total Variation and Empirical Wavelet Transform

Bearings are among the most widely used core components in mechanical equipment. Their failure creates the potential for serious accidents and economic losses. Vibration signature analyses are the most common approach to assess the viability of bearings due to its ease of measurement and high correlation with structural dynamics. However, the collected vibration signals of rolling bearings are usually nonstationary and are inevitably accompanied by noise interference. This makes it difficult to extract the feature frequency for the failed bearing and affects the diagnosis accuracy. The majorization-minimization-based total variation (TV-MM) denoising algorithm effectively removes the noise interference from the signal and highlights the related feature information. The value of its main parameter λ determines the quality of the denoising effect. However, manually selecting parameters requires professional experience in a process that it is time-consuming and laborious, while the use of genetic algorithms is cumbersome. Therefore, an improved particle swarm algorithm (IPSO) is used to find the optimal solution of λ. The IPSO utilises the mutation concept in genetic algorithms to reinitialise the particles with a certain probability after each update. In addition, the empirical wavelet transform (EWT) is an adaptive signal processing method suitable for processing nonlinear and nonstationary signals. Therefore, this paper presents an ensemble analysis method that combines the IPSO, TV-MM, and EWT. First, IPSO is used to optimise the denoising parameter λ. The TV-MM under this parameter effectively removes the background noise interference and improves the accuracy of the subsequent modal decomposition. Then, the EWT is used for the adaptive division to produce a set of sequences. Finally, Hilbert envelope demodulation is performed on each component to realise fault diagnosis. The results from simulations and signals received from defective bearings with outer race fault, inner race fault, and rolling element fault demonstrate the effectiveness of the proposed method for fault diagnosis of rolling bearings

Steady-State Steering Characteristics of Mathematical Model for Semitrailer Based on Variations in Camber Parameters

To master the basic characteristics of steady-state cornering for a semitrailer, this paper summarises the current modelling methods for handling and stability and discusses their limitations. The classical linear mathematical model for a two-degree-of-freedom (DOF) handling and stability system is used to develop a new model. Analysis methods are proposed to introduce the influence of the camber angle and body roll into the model parameters. Thus, a mathematical model for the lateral stability of semitrailer with five DOFs is established. At the same time, a modified formula to calculate the stability factor of the semitrailer is developed with a MATLAB model to solve the dynamic state equation. The mathematical model, which considers the body roll and the changes in the camber angle caused by roll, compares the turning radius ratio and yaw rate as the evaluation index with the classical linear mathematical model of a two-DOF system. The vehicle parameters for three different types of semi-tractor trailers are used to calculate and compare two mathematical models for handling and stability using real vehicle test data. The results show that the new modelling and analysis method proposed in this paper has a high calculation accuracy and fast calculation speed, is clear and concise, and is consistent with the real vehicle test data. In addition, the accuracy of the new mathematical model for handling and stability and the improved stability factor are verified