This paper mainly gives one kind of the detection system of the powder chamber on cubage. It is a multi-sensor sub-system which are composed of the encoder of increment, the piezoelectricity sensor, controlled by the AT89C51 processor, equipped with essential designs in machinery such as motor drive. This system can realize the powder chamber's dynamic and real-time detection. It also can be as one kind of dectection method which be useful to shooting range and other departments.
Objective Athletes’ psychological quality and competitive level are deeply influenced by coaches’ leadership behavior. It is of far-reaching significance to systematically investigate the relationship between them for carrying out scientific training and improving athletes’ competitive level. This study aims to investigate the relationships among coach leadership behavior, the coach-athlete relationship, psychological fatigue, and athletes’ performance, providing insights into enhancing athletes’ sports performance. Methods Using simple random sampling, 556 athletes (44.60% female) were recruited from professional training teams in the Xinjiang and Shanxi provinces of China as the study sample. The sample includes 47 s-class national athletes, 276 first-class national athletes, 171 master-class athletes, and 62 international-level athletes. Data were collected through offline surveys using the Coach Leadership Behavior Scale, the Tennis Performance Scale, the Coach-Athlete Relationship Questionnaire, and the Athlete Psychological Fatigue Questionnaire. Results Democratic leadership behavior, autocratic leadership behavior, training and instruction behavior, social support behavior, and positive feedback behavior are positively correlated with the “coach-athlete” relationship and athlete performance, and negatively correlated with psychological fatigue. The “coach-athlete” relationship and psychological fatigue can serve as both simple mediators and chain mediators between democratic leadership behavior, autocratic leadership behavior, training and instruction behavior, social support behavior, positive feedback behavior, and athlete performance. Conclusion This study systematically explored the complex relationships among coach leadership behavior, the coach-athlete relationship, psychological fatigue, and athletes’ sports performance. The findings suggest that positive coach leadership behavior may contribute to the development of athletes’ performance. Furthermore, the study underscores the significance of the coach-athlete relationship and psychological fatigue as key mechanisms through which coach leadership behavior influences athletes’ sports performance.
Identification of damping characteristics is of significant importance for dynamic response analysis and condition assessment of structural systems. Damping is associated with the behavior of the energy dissipation mechanism. Identification of damping ratios based on the sensitivity of dynamic responses and the model updating technique is investigated with numerical and experimental investigations. The effectiveness and performance of using the sensitivity-based model updating method and vibration monitoring data for damping ratios identification are investigated. Numerical studies on a three-dimensional truss bridge model are conducted to verify the effectiveness of the proposed approach. Measurement noise effect and the initial finite element modelling errors are considered. The results demonstrate that the damping ratio identification with the proposed approach is not sensitive to the noise effect but could be affected significantly by the modelling errors. Experimental studies on a steel planar frame structure are conducted. The robustness and performance of the proposed damping identification approach are investigated with real measured vibration data. The results demonstrate that the proposed approach has a decent and reliable performance to identify the damping ratios.
This paper investigates the possibility and effectiveness of using a recently developed relative displacement sensor for the damage detection of gusset plate conditions in steel truss bridges. The developed sensor is an innovative design offering some advantages and unique features, and is a much easier and cheaper method of structural health monitoring due to the simplicity of its direct measurement of relative displacement without the need for a stable reference point. To investigate the potential applications of the developed sensor to the damage detection of joint conditions, a steel truss bridge model is fabricated in the laboratory and installed with the developed sensors to detect the loosen bolt damage in the gusset plates by using measured relative displacements. Those measured relative displacement measurements from the free vibration tests of both the undamaged and damaged truss models are analyzed, and a damage index based on the wavelet packet energy percentage change is used to detect the existence of the loosen bolt damage in steel truss bridges. Experimental studies demonstrate that the developed relative displacement sensor has a sensitive performance to indicate the joint conditions in steel truss bridges.
On September 6, 2008, the satellite HJ-1B was launched into a sun-synchronous, near-polar orbit. In order to determine temporal changes of the absolute radiometric calibration of the HJ-1B satellite in flight, a program was carried out at DunHuang calibration field, Gansu province of China, from August 19 to 30, 2009. In this work, reflectance -based calibration method was employed to simulate the absolute calibration coefficients of the HJ-1B CCD sensors. Then the cotton field, cement court, water pool and test site was selected to validate the calibration coefficient. The validation results indicated that there had a good agreement between the imaged-based reflectance and the ground measurement of the type of cement court and test site. On the other hand, there had a disagreement of the type of cotton field and water because of the effect of mixed pixel.
A novel, to the best of our knowledge, optical fiber plasmonic sensor based on a tapered coreless fiber (TCF) coating with rolled-up hyperbolic metamaterials (HMMs) is proposed and theoretically studied. The HMMs are composed mainly of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mi mathvariant="normal">A</mml:mi> <mml:mi mathvariant="normal">g</mml:mi> </mml:mrow> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mo>/</mml:mo> </mml:mrow> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msub> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mi mathvariant="normal">T</mml:mi> <mml:mi mathvariant="normal">i</mml:mi> <mml:mi mathvariant="normal">O</mml:mi> </mml:mrow> <mml:mn>2</mml:mn> </mml:msub> </mml:mrow> </mml:math> multi-layer composite materials. We can effectively control the surface plasmon resonance (SPR) wavelengths by adjusting the ratio of metal in two-layer ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mi>R</mml:mi> </mml:math> ), the number ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mi>N</mml:mi> </mml:math> ), and thickness ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mi>T</mml:mi> </mml:math> ) of two-layer on the HMMs. Spectral quality can be improved by changing the core diameter of TCF. According to the effective medium theory and finite element method, HMMs of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mi>R</mml:mi> <mml:mo>=</mml:mo> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mn>0.3</mml:mn> </mml:mrow> </mml:math> , <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mi>T</mml:mi> <mml:mo>=</mml:mo> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mn>30</mml:mn> </mml:mrow> <mml:mspace width="thickmathspace"/> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mi mathvariant="normal">n</mml:mi> <mml:mi mathvariant="normal">m</mml:mi> </mml:mrow> </mml:math> , <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mi>N</mml:mi> <mml:mo>=</mml:mo> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mn>3</mml:mn> </mml:mrow> </mml:math> , and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mi>D</mml:mi> <mml:mo>=</mml:mo> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mn>20</mml:mn> </mml:mrow> <mml:mspace width="thickmathspace"/> <mml:mtext>µ</mml:mtext> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mi mathvariant="normal">m</mml:mi> </mml:mrow> </mml:math> can provide an average sensitivity of 9127.86 nm/RIU (refractive index unit) in an external refractive index (ERI) of 1.33–1.40 and have a depth of SPR dip figure of merit of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mn>65.32</mml:mn> </mml:mrow> <mml:mspace width="thickmathspace"/> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msup> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mi mathvariant="normal">R</mml:mi> <mml:mi mathvariant="normal">I</mml:mi> <mml:mi mathvariant="normal">U</mml:mi> </mml:mrow> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mo>−</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:msup> </mml:mrow> </mml:math> , which is an order of magnitude higher than 50 nm silver, for an ERI of 1.34–1.35. Also, the optical fiber plasmonic sensor integrated with roll-up HMMs shows performance superior to normal HMMs, thus providing certain guidance for future research.
Traffic noise has become one of the most significant issues in environmental pollution complaints. In some cases, tyre/road noise level has exceeded the critical values of environmental regulations by more than 10 dB (A), and using single technical method, such as noise reducing pavement or noise barrier, cannot solve the problem effectively. In this paper, research and application were carried out by considering combination of both noise reducing pavement and barrier. Based on analysis of characteristics of tyre/road noise spectrum, a design method of sound absorption performance of barrier which will compensate the absorption ability of the pavement is proposed. Three types of noise barrier panel, namely diffusive, interference-type, and diamond-shaped sound absorption panels, were developed, which provide good complements to the absorption spectrum of porous asphalt pavement. Trail section was built for validation on a practical expressway. Noise reducing pavement designed by considering travel lane differences were firstly constructed, and noise barriers with the three different types of sound absorption panel were installed along the road section. After implementation, it shows that noise levels measured in the surrounding villages can be reduced by 10~13dB (A), and this method is proved effect for eliminating the severe pollution of tyre/road noise.
摘要: CRH1型动车组最初采用的LMA型车轮踏面不能很好地匹配列车的悬挂参数,影响了列车在直线和大半径曲线上运行时的稳定性,后被新设计的LMD型踏面取代。LMD型踏面为列车运行提供更好的稳定性,却出现了严重的轮缘磨损和钢轨侧磨现象。此次优化过程首先对LMA和LMD型踏面的综合性能进行理论分析,并依据当前两种型面使用中出现的问题,以保证车辆直线运行稳定性与减小通过小半径曲线时的轮缘磨耗为目标,建立数值优化模型,并采用改进的粒子群优化算法对模型进行了求解。结果表明,该方法具有较快的计算速度与收敛性;获得的新型车轮踏面可以保证CRH1型动车组较好的直线运行稳定性,小半径曲线通过时较小的轮轨横向力和轮对冲角。研究内容为车轮型面的多目标优化提供了可行方案,为改善CRH1型动车组综合服役性能提供理论参考。
We introduce deep learning technique to predict the beam propagation factor M^2 of the laser beams emitting from few-mode fiber for the first time, to the best of our knowledge. The deep convolutional neural network (CNN) is trained with paired data of simulated near-field beam patterns and their calculated M^2 value, aiming at learning a fast and accurate mapping from the former to the latter. The trained deep CNN can then be utilized to evaluate M^2 of the fiber beams from single beam patterns. The results of simulated testing samples have shown that our scheme can achieve an averaged prediction error smaller than 2% even when up to 10 eigenmodes are involved in the fiber. The error becomes slightly larger when heavy noises are added into the input beam patterns but still smaller than 2.5%, which further proves the accuracy and robustness of our method. Furthermore, the M^2 estimation takes only about 5 ms for a prepared beam pattern with one forward pass, which can be adopted for real-time M^2 determination with only one supporting Charge-Coupled Device (CCD). The experimental results further prove the feasibility of our scheme. Moreover, the method we proposed can be confidently extended to other kinds of beams provided that adequate training samples are accessible. Deep learning paves the way to superfast and accurate M^2 evaluation with very low experimental efforts.
Rural community population forecasting has important guiding significance to rural construction and development. In this study, a novel grey Bernoulli model combined with an improved Aquila Optimizer (IAO) was used to forecast rural community population in China. Firstly, this study improved the Aquila Optimizer by combining quasi-opposition learning strategy and wavelet mutation strategy, and proposed the new IAO algorithm. By comparing with other algorithms on CEC2017 test functions, the proposed IAO algorithm has the advantages of faster convergence speed and higher convergence accuracy. Secondly, based on the data of China’s rural community population from 1990 to 2019, a consistent fractional accumulation nonhomogeneous grey Bernoulli model called CFANGBM(1, 1, b, c) was established for rural population forecasting. The proposed IAO algorithm was used to optimize the parameters of the model, and then the rural population of China was predicted. Four error measures were used to evaluate the model, and by comparing with other forecasting models, the experimental results show that the proposed model had the smallest error between the forecasted value and the real value, which illustrates the effectiveness of using the IAO algorithm to solve CFANGBM(1, 1, b, c). At the end of this paper, the forecast data of China’s rural population from 2020 to 2024 are given for reference.
The satellite navigation signal simulator, as a high-precise standard signal source, can generate such satellite navigation signals as GPS, GLONASS and galileo and provide a simulation environment for the development and test of navigation receiver. This paper presents an overview of the main satellite navigation signal simulators in the world and analyzes their architectures.
The aim of this paper was to carry out numerical simulations of structural health monitoring applications for plate structures using the boundary element method (BEM). The fundamental symmetric Lamb mode (S0) is chosen for the SHM applications. The propagation, reflection and diffraction of the S0 mode Lamb wave are modelled using a boundary element formulation based on the plane stress theory. Piezoelectric (PZT) actuators are mounted on plate surfaces to excite the S0 mode wave. A semi-analytical method is adopted to couple the PZT actuators and the host plate. Numerical results show that BEM is a very efficient simulation method for the structural health monitoring of plates.
This paper proposes a crack detection method for rail joint screw holes based on the ultrasonic nonlinearity. Experimental and numerical studies are conducted to validate the performance of the proposed approach. The ultrasonic signals excited and received at the rail head are processed by spectral analysis and Wavelet Packet Decomposition (WPD). The third harmonic can be clearly observed from the spectrum analysis, which is supposed to be the nonlinearity of structures. Further, WPD is used to decompose the frequency components of the received signals. A damage index (DI) is defined based on the energy percentage of the energy in the WPD node containing the third harmonic with respect to the total energy of the received signal. It is found that the DI relating to the third harmonic increases with an approximately linear relationship when the crack grows bigger. It can provide a basis for the crack detection and quantification for the rail joint screw holes. A finite element model of the experimentally tested rail is also developed and numerical studies are conducted to verify the ultrasonic nonlinearity in the rail structure. Numerical results have the same trend with the experimental results, which verifies the effectiveness of the proposed method for crack detection in rail joints based on the high order ultrasonic nonlinear harmonics.
