查看更多>>摘要：A rapid progress in the field of bioelectronics has enforced to develop standardized performance tests for electrodes serving as tissue interfaces. One of the most routinely applied tests comprises the determination of a charge storage capacity (CSC), which is a parameter used to assess the amount of charge than can be stored within the electrode material. The aim of this work was to indicate challenges and limitations of a current method used to measure CSC, which is based on cyclic voltammetric measurements under arbitrarily chosen experimental conditions, and the risks of overestimation/underestimation of determined capacitance values. Acknowledging the necessity to develop standardized performance tests applicable in bioelectronics, we have provided a set of guidelines for selecting experimental conditions suitable for a reliable CSC analysis.
查看更多>>摘要：Plastic viscosity is a key property of ultra-high-performance concrete (UHPC) and must be controlled during the mixing to achieve desired fresh and hardened properties. This paper presents a video recognition technology for real-time assessment of plastic viscosity using a video captured by a camera during the mixing of UHPC. A long-term recurrent convolutional network is proposed to extract spatial and temporal features of flowing UHPC from the video and correlate the features with plastic viscosity measured from a rheometer, thus enabling assessment of plastic viscosity using videos. This research also investigates the effects of plastic viscosity on the fiber dispersion and orientation, air content, and flexural properties of UHPC. The results show that the plastic vis-cosity significantly influences fiber distribution and air void content, thus affecting the flexural properties of UHPC. The presented method enables real-time assessment of plastic viscosity for control of flexural properties and air void content of UHPC. This study will greatly facilitate quality control for production of UHPC.
查看更多>>摘要：It is significant to detect railway intrusion for railway safety. Unlike indoors, the railway is a complex environment with many interferences leading to false positives in the intrusion detection algorithm. However, there is a lack of research on effective intrusion detection in complex railway scenes. To solve these problems, the paper proposes RailDet, an effective railway intrusion detection method using dynamic intrusion region and lightweight neural network, which has high accuracy, low false-positives and high speed. RailDet consists of two stages. Firstly, the intrusion localization algorithm is used to obtain dynamic intrusion regions. Secondly, the object recognition based on lightweight neural network processes intrusion regions to obtain the coordinates and category. Finally, RailDet is validated on Chinese railways with various weathers and locations, which achieves 96.90% accuracy, 0.24% false-positive rate and 0.043 s/image. Moreover, the proposed method is very meaningful for the application of deep learning and not limited to railway.
查看更多>>摘要：Monitoring the friction stir welding is an important part of intelligent systems. In this paper, we designed welding experiments based on the single factor variable method and studied the roughness of the weld surface in detail. By analysing the variation in the roughness, the theoretical formulas of roughness Ra and Rsm are ob-tained. The deviation between the measured value and the theoretical value of Ra can be used to evaluate the welding condition. An industrial camera was used to capture the texture images of the weld surface and process them to extract features. Based on the fractional Brownian motion model, the fractal dimension of statistical significance was obtained from the power spectrum of the gray distribution in texture images. The results show that the extracted fractal dimension can accurately reflect the changes in roughness Ra. This research is helpful to realize welding condition monitoring based on machine vision systems.
Alipanahi, AnahitaMahboubkhah, MehranBarari, Ahmad
17页
查看更多>>摘要：In the present study, a strain gauge-based low-priced dynamometer and a customized data acquisition system are developed to simultaneously measure torque and tri-axial cutting forces in end-milling and drilling operations. This design includes 24 strain gauges bonded on four octagonal rings. To achieve the utmost sensitivity and overcome the cross-talk among the torque and components with gauges located at similar locations, finite element analyses have been practiced. These analyses determined the best composition of the gauges to attain the desired results. A model is then used to describe the system mathematically, and modal analyses have been conducted to estimate the dynamometer's working range. Face milling operations have been run to test the dynamometer's efficiency. The designed dynamometer was accredited by a commercially available dynamometer as a reliable and affordable instrument to be used in low to medium-speed milling processes and can be adopted by industries and laboratories with limited resources.
查看更多>>摘要：This paper proposes a variational Bayesian-based cubature Kalman filter to solve the state estimation problem of nonlinear discrete-time systems under dynamic model mismatch and outliers interference, which occurs in the maneuvering target tracking system. In the proposed filter, the measurement noise is divided into the normal measurement noise and the outlier noise, and two inverse Wishart distributions with different degree of freedom parameters are used to model the unknown normal measurement noise covariance and the unknown outlier noise covariance, respectively. To overcome outliers interference, the judgment factor which follows the Bernoulli-beta distribution is designed to identify the type of measurement noise. Meanwhile, the input vector which follows the Gaussian distribution is introduced to realize the dynamic model revision. The state, the judgment factor, the normal measurement noise covariance, the outlier noise covariance, and the input vector are jointly estimated under the variational Bayesian framework. The numerical simulation is illustrated to verify the performance of the proposed filter and the corresponding results show that the proposed filter has good state estimation performance and robustness.
查看更多>>摘要：Hydrophones are one of the main sensors for underwater acoustic signal detection, and their positioning accuracy is closely related to their sensitivity. However, in practice, hydrophones need to work in different depths of water environment. The ciliated MEMS vector hydrophone has a four-beam structure and has a certain anti interference ability against hydrostatic pressure. However, due to the manufacturing process and other reasons, there may be certain errors in the production of varistors, which leads to the hydrophone's resistance to hydrostatic pressure. The resistance to the impact is reduced. Therefore, studying the influence of hydrostatic pressure environment on the sensitivity of MEMS vector hydrophones is of great significance to the application of MEMS vector hydrophones. According to the application environment of MEMS vector hydrophone, the sensitivity of MEMS vector hydrophone is studied in this paper within the range of hydrostatic pressure 1 atm ~ 12 MPa. In this paper, the influence of hydrostatic pressure on the sound transmission loss and piezoresistor are studied to theoretically verify that the hydrostatic pressure has little effect on the sensitivity of MEMS vector hydrophone. It is verified by COMSOL5.6 software simulation that the sensitivity changes within the pressure range of 1 dB. In order to facilitate the experiment of the MEMS vector hydrophone in the hydrostatic environment, this paper proposed a method of combining an external sound source with a marine environment simulation test machine. It is concluded that within the test pressure range, the sensitivity change of the MEMS vector hydrophone fluctuates within & PLUSMN;1 dB.
查看更多>>摘要：AISI52100 tool steel is commonly used for under high temperature and fatigue applications owing to superior tensile strength, corrosion resistance, and stiffness, Therefore, it is called difficult-to-cut material. In this work, a novel application of dry ice blasting as a cooling technology in milling AISI52100 tool steel is proposed to measure the cutting temperature, surface hardness, cutting forces, residual stresses, surface roughness, and tool wear and compared to minimum quantity lubrication (MQL). The experiments are performed at varying cutting speeds Vc between 75-300 m/min, feed per tooth fz (0.04-0.12 mm/z), and fixed axial/radial depth of cut. Experimental measurements have shown that dry ice blasting reduced the cutting temperature by 20% compared to MQL. Further, surface roughness is decreased by 7%, surface hardness by 6%, residual stresses by 8%, and 22% prolonged tool life in comparison with MQL. The high level of cutting speed (300 m/min) is favorable to achieving appropriate machining characteristics. In a nutshell, interesting results of machinability under dry ice blasting present it as a sustainable alternative technology for the advancement of the manufacturing sector.
查看更多>>摘要：In the new generation of nuclear energy system, the thickness of the coating layer of tristructural isotropic (TRISO)-coated fuel particles is one of the most important parameters. Recently, some visual-based methods have been developed for the thickness measurement of each coating layer, but the existing method still lacks of practicality. In this study, an advanced visual system combined with the ceramographic section method and deep learning algorithms is designed to automatically measure the thickness values of each coating layer. In the designed visual system, an automatic image acquisition method is first achieved. After that, an accurate thickness measurement method is proposed based on the designed image segmentation model. Finally, to enhance the reliability and consistency of the measurement results, a tracing method is developed for the designed measurement system. The experimental results demonstrate that the designed system can accurately automatically measure the thickness values of each coating layer.
查看更多>>摘要：Accurate measurement of coaxiality for the aero-engine rotor is a prerequisite for precision assembly. Often a few acceptable measurements of concentricity taken along a single measuring datum are considered a guarantee of coaxiality for the aero-engine rotor. However, it is hard to ensure the measurement accuracy. This paper proposes a coaxiality measurement method based on common datum axis. To investigate the influence of different datum axes on the measuring value of rotor coaxiality, three measuring models of rotor coaxiality are established and compared, which are based on connection centerline, single measuring datum and common datum axis, respectively. Experiments show that the measuring value of coaxiality based on common datum axis is smaller and more accurate than other two different models of rotor coaxiality. The research can provide reference guidance for the measurement and control of the aero-engine rotor coaxiality during the assembly process.
NSTL
Elsevier