Bo Zhao and Hongjie Hu
The purpose of this paper is to develop a new inverse controller for servo‐system position tracking control based on neural network (NN) and model reference adaptive control…
Abstract
Purpose
The purpose of this paper is to develop a new inverse controller for servo‐system position tracking control based on neural network (NN) and model reference adaptive control (MRAC).
Design/methodology/approach
First, the model of general servo‐systems is analyzed. Then, a MRAC based on neural network control (NNC) is proposed with mathematical prove of stability. In addition, several simulation cases and experiments are listed to verify the usability of the control scheme.
Findings
This scheme consists of an MRAC, an online NN controller and a robust controller in velocity‐loop. For reducing influence which arose from modeling error, unknown model dynamics, parameter variation, and load changes, the NN controller is introduced to counteract the various influence mentioned above dynamically. MRAC, NNC, and robust controller adjust system to track the approximate velocity‐loop reference model. In this way, the position‐loop is not sensitive to the disturbance on velocity‐loop, and the whole velocity‐loop can be treated as a simple linear model when designing the other parts of the system. In addition, a novel inverse control method based on linear velocity signal filter is introduced to this scheme. In this case, the MRAC, NNC, and robust controller perform as an adaptive inverse controller, which keeps the velocity signal tracking the position loop controller output.
Originality/value
The paper presents a new inverse controller with NNC and MRAC which is practical and flexible.
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Bo Hu, Heng Zhou, Yubao Gui, Peng Zhai, Lihua Zhang and Zhiyan Dong
This paper aims to design a novel hybrid terrestrial-aerial robot, FlyingDog, including its modeling and implementation. By combining the complementary advantages of a quadrotor…
Abstract
Purpose
This paper aims to design a novel hybrid terrestrial-aerial robot, FlyingDog, including its modeling and implementation. By combining the complementary advantages of a quadrotor drone and a quadruped robot, FlyingDog demonstrates excellent maneuverability and high energy efficiency, showcasing great potential for applications in industrial inspection, field exploration, and search and rescue operations.
Design/methodology/approach
By integrating propellers and leg mechanisms, FlyingDog achieves hybrid motion, encompassing both aerial flight and ground movement. This paper first provides an overview of the robot’s structural design, emphasizing the minimization of interactions between the aerial and ground mechanisms while balancing the thrust-to-weight ratio and payload capacity. A distributed control framework is then proposed to achieve the hybrid motion, alongside the development of corresponding control strategies to ensure stability during various movements.
Findings
Experiments conducted in real-world conditions validated FlyingDog’s performance in terms of motion stability, energy efficiency, and obstacle-crossing ability. The results demonstrate that FlyingDog exhibits outstanding mobility by combining ground locomotion with aerial flight capabilities, allowing it to overcome challenging obstacles in purely ground-based mode. In ground mode, the robot achieved an energy efficiency of up to 93.5%.
Originality/value
The hybrid terrestrial-aerial robot presented in this paper features stable land and aerial mobility, a lightweight structure, high energy efficiency, and low manufacturing costs, making it a valuable innovation in the field of robotics.
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Hongjuan Yang, Lin Fu, Yanhua Liu, Weiji Qian and Bo Hu
This paper aims to investigate the delamination wear properties of a carbon strip in a carbon strip rubbing against a copper wire at the high-sliding speed (380 km/h) with or…
Abstract
Purpose
This paper aims to investigate the delamination wear properties of a carbon strip in a carbon strip rubbing against a copper wire at the high-sliding speed (380 km/h) with or without electrical current.
Design/methodology/approach
The friction and wear properties of a carbon strip in a carbon strip rubbing against a copper wire are tested on the high-speed wear tester whose speed can reach up to 400 km/h. The test data have been collected by the high-speed data collector. The worn surfaces of the carbon strip are observed by the scanning electron microscope.
Findings
It was found that there was a significant increase of the delamination wear with the decrease of the normal load when the electric current is applied. The size of the flake-like peeling also increases with the decrease of normal load. The delamination wear extends gradually from the edge of the erosion pits to the surrounding area with the decrease of the normal load. However, the delamination wear never appears in the absence of electric current. It is proposed that the decreased normal load and the big electrical current are the major causes of the delamination wear of the carbon strip.
Originality value
The experimental test at high-sliding speed of 380 km/h was performed for the first time, and the major cause of the delamination was discovered in this paper.
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Bo Hu, Runqiao Yu and Jian Liu
This paper aims to clarify the transient electromagnetic method used for the nondestructive testing of the corrosion of an in-service buried metal pipeline in trenchless state.
Abstract
Purpose
This paper aims to clarify the transient electromagnetic method used for the nondestructive testing of the corrosion of an in-service buried metal pipeline in trenchless state.
Design/methodology/approach
The paper designed corrosion models indoor and infield for testing. A method for calculating the residual wall thickness of metal pipelines was also proposed. The calculation method was verified by the test results. In the test, the receiving probe was improved by the addition of a Mn-Zn ferrite core. The amplitudes of the test results obviously increased, and the calculation accuracy was improved.
Findings
The paper states that the transient electromagnetic method can detect the uniform corrosion distribution of a certain section of a pipeline. A multi-channel profile of the induced electromotive force and the calculated values of the residual wall thickness can be used to confirm the position and degree of corrosion defects, respectively.
Research limitations/implications
The transient electromagnetic method is more effective for large-area corrosion than for localized corrosion (pitting).
Practical implications
The paper includes implications for the development of nondestructive testing method of the corrosion of an in-service buried metal pipeline.
Originality/value
This paper proved the feasibility and reliability of using transient electromagnetic method to test the corrosion of a buried metal pipeline based on experimental study.
Bo Yan, Ning Hu, Xin Lu and Masaki Kameyama
The governing equations for dynamic transient analysis of a fluid‐saturated two‐phase porous medium model based on the mixture theory are presented. A penalty finite element…
Abstract
The governing equations for dynamic transient analysis of a fluid‐saturated two‐phase porous medium model based on the mixture theory are presented. A penalty finite element formulation is derived with the general Galerkin procedure of the finite element method (FEM), and the obtained dynamic system equation can be solved with implicit or explicit time integration method, which is discussed in this paper. Using this method, a porous medium column under impulsive loading is analyzed and the results reveal the phenomena of one‐dimensional wave propagation, which are consistent with analytical solutions. Furthermore, two numerical examples of two‐dimensional problems demonstrate the existence of two body waves, i.e. longitudinal (P‐type) and transverse (S‐type) waves in porous media, and the Rayleigh wave in the vicinity of the surface of porous media.
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Na Xu, Yanxiang Liang, Chaoran Guo, Bo Meng, Xueqing Zhou, Yuting Hu and Bo Zhang
Safety management plays an important part in coal mine construction. Due to complex data, the implementation of the construction safety knowledge scattered in standards poses a…
Abstract
Purpose
Safety management plays an important part in coal mine construction. Due to complex data, the implementation of the construction safety knowledge scattered in standards poses a challenge. This paper aims to develop a knowledge extraction model to automatically and efficiently extract domain knowledge from unstructured texts.
Design/methodology/approach
Bidirectional encoder representations from transformers (BERT)-bidirectional long short-term memory (BiLSTM)-conditional random field (CRF) method based on a pre-training language model was applied to carry out knowledge entity recognition in the field of coal mine construction safety in this paper. Firstly, 80 safety standards for coal mine construction were collected, sorted out and marked as a descriptive corpus. Then, the BERT pre-training language model was used to obtain dynamic word vectors. Finally, the BiLSTM-CRF model concluded the entity’s optimal tag sequence.
Findings
Accordingly, 11,933 entities and 2,051 relationships in the standard specifications texts of this paper were identified and a language model suitable for coal mine construction safety management was proposed. The experiments showed that F1 values were all above 60% in nine types of entities such as security management. F1 value of this model was more than 60% for entity extraction. The model identified and extracted entities more accurately than conventional methods.
Originality/value
This work completed the domain knowledge query and built a Q&A platform via entities and relationships identified by the standard specifications suitable for coal mines. This paper proposed a systematic framework for texts in coal mine construction safety to improve efficiency and accuracy of domain-specific entity extraction. In addition, the pretraining language model was also introduced into the coal mine construction safety to realize dynamic entity recognition, which provides technical support and theoretical reference for the optimization of safety management platforms.
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Prarthana Rao, Min Jee Yamada Park and Samantha Jeffries
To date, intersectional feminist criminological enquiry concerned with exploring junctions of gender and ethnicity amongst incarcerated women, has mainly come from studies…
Abstract
To date, intersectional feminist criminological enquiry concerned with exploring junctions of gender and ethnicity amongst incarcerated women, has mainly come from studies undertaken in western nations. In this chapter, we present findings from research undertaken in Thailand that explored incarcerated ethnic minority women’s backgrounds, situational contexts surrounding their criminalization and criminal justice system experiences, with particular attention paid to women’s time in prison. Our purpose was to examine how gender and ethnicity intersected, impacting the lived experiences of criminalized ethnic minority women before and during their incarceration. Findings revealed the ways in which these women are marginalized inside and outside prison walls. On the outside, the women struggled with patriarchal systems of power, both within and beyond their communities. They were subjugated as women and by discourses of ethnic othering. Under-education, poverty, living with state, community, familial and intimate partner violence, trauma, and other adversity were key aspects of the women’s pre-prison lives and created the contexts from which they came into conflict with the law. The women faced challenges in accessing justice and, once imprisoned, gender and ethnicity intersected in several domains, to impact their carceral experiences.
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Ningning Hu, Jiguang Han and Bo Hu
– The purpose of this paper is to study the effect of silver (Ag) precursor on friction and wear.
Abstract
Purpose
The purpose of this paper is to study the effect of silver (Ag) precursor on friction and wear.
Design/methodology/approach
Thermogravimetric analysis of the oil with Ag precursor and X-ray diffraction of the decomposition product of the Ag complex were performed. The tribological behavior was evaluated on a UMT-3M Tribometer (CETR) using pure military-grade oil lubricant and the prepared lubricant at room temperature and at 300°C. Energy-dispersive spectroscopy of the chemical composition on the wear scar was performed.
Findings
When there is 1 weight per cent Ag precursor in the lubricant, the coefficient friction reduces by about 8 per cent at room temperature and by about 14 per cent at 300°C, and the wear probability also decreases, from moderate wear to mild wear at 300°C. There were more productions which could form metal Ag boundary films possessing low shearing stress and excellent lubricity at 300°C.
Originality/value
Ag precursors used as additives in a military-grade oil lubricant and excellent lubricity found at high temperature.
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M.R. Pagnola, F.D. Saccone, A. Ozols and H. Sirkin
The purpose of this paper is to introduce a simplified method, based on an improvement to the actual second‐order approximation to magnetic hysteresis curves, to calculate an…
Abstract
Purpose
The purpose of this paper is to introduce a simplified method, based on an improvement to the actual second‐order approximation to magnetic hysteresis curves, to calculate an estimation of quasi‐static hysteresis loops of ferromagnetic materials.
Design/methodology/approach
The addition of a new dB(B) function is proposed to second‐order rational approximation for the upward and downward magnetic quasi‐static hysteresis loop. The new semi‐empirical approach is tested with typical cycles of commercial Ni‐ferrites (ferroxcube) and Ni standards using a vibrating sample magnetometer (VSM).
Findings
The model is simple and a fast tool to reproduce with reasonable accuracy the hysteresis loops based on appropriate parameters of materials under analysis. The proposed extension to the Rivas model has reduced the maximum difference between experimental and modeled values from 19 to 0.08 per cent in the approximation to different hysteresis cycles of the magnetic materials studied here.
Originality/value
This paper presents an improvement to second‐order rational functions approach for fitting of hysteresis loops with simple added functions.