Pan-Pan Li, Feng Gao, Yan Li and Bo Yang
The serious friction caused by the fluctuation of friction occurs when start-up and will reduce the positioning accuracy of the servo axes of high precision machine tools, the…
Abstract
Purpose
The serious friction caused by the fluctuation of friction occurs when start-up and will reduce the positioning accuracy of the servo axes of high precision machine tools, the purpose of this paper is to study the friction fluctuation characteristics of friction coefficients between interfaces under different working conditions.
Design/methodology/approach
HT200 and 45# materials were experimentally studied by friction and wear testing machine UMT-3, the variation of friction coefficient under different working conditions (different start-up conditions, the variation of lubrication state area and different roughness) were measured.
Findings
The results show that the larger start-up acceleration shortens the pre-sliding time of the interface friction, makes the friction coefficient decrease faster, reduces the mixed lubrication area of the contact surface and makes the contact surface reach the stable lubrication state quickly. It can be concluded that the larger roughness surface will lead to the larger mixed lubrication area, the larger static friction coefficient and the larger drop between static and dynamic friction coefficient and easy to cause friction vibration.
Originality/value
The results reveal the friction fluctuation rule of the metal interface during the different start-up process, which is of guiding significance to reveal the lubrication principle and mechanism of the mechanical interface.
Peer review
The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-11-2019-0482/
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Feng Gao, Pan-Pan Li and Yan Li
For ball screw feed system, a sudden start or stop has a great influence on the transmission stiffness, so the axial stiffness mutation of feed system will occur. The purpose of…
Abstract
Purpose
For ball screw feed system, a sudden start or stop has a great influence on the transmission stiffness, so the axial stiffness mutation of feed system will occur. The purpose of this paper is to study the influence of acceleration on the transmission stiffness and dynamic characteristics of the ball screw feed system.
Design/methodology/approach
Taking the ball screw feed system as a research object, on the basis of the Hertz contact theory and the mixed element method, axial stiffness model and dynamic model are established. And the system stability was analyzed by the time history diagram and Phase-plane portrait diagram. The feed system was analyzed theoretically and experimentally, the experimental results are in good agreement with the model results.
Findings
Lead screw lead angle, preload, load and start acceleration affected ball-screw pair, bearing and transmission stiffness. And the load, nut contact stiffness, bearing contact stiffness, preload have a large effect on the transmission stiffness. The results show that a certain acceleration value will make the axial stiffness abrupt change.
Originality/value
This research provides a useful theoretical support for ensuring a good dynamic for the ball screw feed system.
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Yudan Dou, Wenjuan Hou, Xueya Yan, Xin Jin and Pan Li
Prefabricated construction (PC) is increasingly recognized for its sustainability and is being vigorously promoted worldwide. However, its adoption in developing countries remains…
Abstract
Purpose
Prefabricated construction (PC) is increasingly recognized for its sustainability and is being vigorously promoted worldwide. However, its adoption in developing countries remains suboptimal, with existing studies predominantly focusing on policy frameworks or the impact of a single policy instrument. This study addresses this research gap by optimizing the path of PC promotion from the perspective of policy mixes.
Design/methodology/approach
The study employs fuzzy-set qualitative comparative analysis (fsQCA) in conjunction with necessary condition analysis, to explore effective policy configurations for PC promotion. A comprehensive collection of 171 PC-related policies issued by the Chinese government was analyzed using text mining to identify antecedent conditions of configuration. Data were further obtained through a questionnaire survey involving 263 valid responses, with fsQCA used to derive the optimal policy configurations.
Findings
The analysis identified six distinct combination paths for effective policy configurations. Land supply and governmental procurement were found to be core conditions, while fiscal and taxation financial measures emerged as marginal conditions prevalent across all paths. These findings suggest that land supply policies are particularly suitable for regions with limited land resources, such as Shanghai, while government procurement is more effective in regions like Xinjiang, where PC awareness is still developing.
Practical implications
In practice, the conclusions enable policymakers to clearly understand policy instruments, thereby finding differentiated pathways for promoting PC with comparable effects. The proposed recommendations help advance PC development effectively while reducing financial burden and minimizing resource waste. This provides important guidance for PC development across different regions or stages, helps address regional imbalances in PC development, and ultimately contributes to the broader goal of sustainable urban development.
Originality/value
This study significantly enriches the research on PC policy combinations by utilizing more comprehensive and robust data, thereby enhancing the universal applicability of the findings. The results provide valuable references for policymakers in different regions, helping to address regional imbalances in PC development and facilitating the construction industry’s transition towards greater intelligence and sustainability.
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Alhamzah Alnoor, Paiman Ahmad, Shwan Mohammed Mustafa, Md Imtiaz Mostafiz, Franklin Akosa and Xin Ying Chew
Introduction: Based on the given experiences, many government institutions failed in their strategic management and planning for managing COVID-19. Meanwhile, when a crisis…
Abstract
Introduction: Based on the given experiences, many government institutions failed in their strategic management and planning for managing COVID-19. Meanwhile, when a crisis disrupts a system, institutions lose their direction and fail to make necessary responses.
Purpose: The current study highlighted the impact of social justice and modern governance in providing equitable healthcare services and dealing with crises during the COVID-19 pandemic in developing countries.
Methodology: Cross-country analyses were used based on captured secondary data. We evaluated several indices, including, for example, Crisis Index Indicators, Worldometers, and the Global Health Security (GHS) Index 2019.
Findings: According to the GHS (2019) data, public health service delivery equity was ineffective, socially unjust, and unfair treatment was experienced in the context of the conflict-affected countries. Most conflict-affected countries (Iraq, Nigeria, Afghanistan, and Venezuela) did not have guidelines or public reports committing to providing prioritized healthcare services to the public and healthcare workers. The experience of conflict-affected countries has shown that healthcare disparities still exist. While many governments in conflict-affected countries failed to give equitable access to healthcare services during the COVID-19 pandemic to the public.
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Chaoran Liu, Yufeng Su, Jinzhao Yue, Junjie Wang, Weiwei Xia, Dongxue Li, Wen Wang, Pan Wang and Zhiyong Duan
A self-adaptive piston is designed for the compressional gas cushion press nanoimprint lithography system. It avoids the lube pollution and high wear of traditional piston.
Abstract
Purpose
A self-adaptive piston is designed for the compressional gas cushion press nanoimprint lithography system. It avoids the lube pollution and high wear of traditional piston.
Design/methodology/approach
The self-adaptive piston device consists of symmetrical piston bodies, piston rings and other parts. The two piston bodies are linked by a ball-screw. The locking nut adjusts the distance between two piston bodies to avoid the piston rings from being stuck. The piston rings are placed between two piston bodies.
Findings
The simulation results based on COMSOL indicate that cylinder vibration caused by self-adaptive piston is 15.9 times smaller than the one caused by a traditional piston.
Originality/value
The self-adaptive piston is superior to the traditional piston in decreasing cylinder vibration.
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Xiufeng Zhang, Jitao Dai, Xia Li, Huizi Li, Huiqun Fu, Guoxin Pan, Ning Zhang, Rong Yang and Jianguang Xu
This paper aims to develop a signal acquisition system of surface electromyography (sEMG) and use the characteristics of (sEMG) signal to interference action pattern.
Abstract
Purpose
This paper aims to develop a signal acquisition system of surface electromyography (sEMG) and use the characteristics of (sEMG) signal to interference action pattern.
Design/methodology/approach
This paper proposes a fusion method based on combining the coefficient of AR model and wavelet coefficient. It improves the recognition rate of the target action. To overcome the slow convergence speed and local optimum in standard BP network, the study presents a BP algorithm which combine with LM algorithm and PSO algorithm, and it improves the convergence speed and the recognition rate of the target action.
Findings
Experiments verify the effectiveness of the system from two aspects the target motion recognition rate and the corresponding reaction speed of the robotic system.
Originality/value
The study developed a signal acquisition system of sEMG and used the characteristics of (sEMG) signal to interference action pattern. The myoelectricity integral values are presented to determine the starting point and end point of target movement, which is more effective than using single sample point amplitude method.
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Li Li, Tong Huang, Chujia Pan, J.F. Pan and Wenbin Su
The purpose of this paper aims to investigate the adaptive impedance control and its optimized PSO algorithm for force tracking of a dual-arm cooperative robot. Because the…
Abstract
Purpose
The purpose of this paper aims to investigate the adaptive impedance control and its optimized PSO algorithm for force tracking of a dual-arm cooperative robot. Because the dual-arm robot is directly in contact with external environment, controlling the mutual force between robot and external environment is of great importance. Besides, a high compliance of the robot should be guaranteed.
Design/methodology/approach
An impedance control based on Particle Swarm Optimization (PSO) algorithm is designed to track the mutual force and achieve compliance control of the robot end.
Findings
The experimental results show that the impedance control coefficients can be automatically tuned converged by PSO algorithm.
Originality/value
The system can reach a steady state within 0.03 s with overshoot convergence, and the force fluctuation range at the steady state decreases to about ±0.08 N even under the force mutation condition.
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Hajar Fatemi, Erica Kao, R. Sandra Schillo, Wanyu Li, Pan Du, Nie Jian-Yun and Laurette Dube
This paper examines user generated social media content bearing on consumers’ attitude and belief systems taking the domain of natural food product as illustrative case. This…
Abstract
Purpose
This paper examines user generated social media content bearing on consumers’ attitude and belief systems taking the domain of natural food product as illustrative case. This research sheds light on how consumers think and talk about natural food within the context of food well-being and health.
Design/methodology/approach
The authors used a keyword-based approach to extract user generated content from Twitter and used both food as well-being and food as health frameworks for analysis of more than two million tweets.
Findings
The authors found that consumers mostly discuss food marketing and less frequently discuss food policy. Their results show that tweets regarding naturalness were significantly less frequent in food categories that feature naturalness to an extent, e.g. fruits and vegetables, compared to food categories dominated by technologies, processing and man-made innovation, such as proteins, seasonings and snacks.
Research limitations/implications
This paper provides numerous implications and contributions to the literature on consumer behavior, marketing and public policy in the domain of natural food.
Practical implications
The authors’ exploratory findings can be used to guide food system stakeholders, farmers and food processors to obtain insights into consumers' mindset on food products, novel concepts, systems and diets through social media analytics.
Originality/value
The authors’ results contribute to the literature on the use of social media in food marketing on understanding consumers' attitudes and beliefs toward natural food, food as the well-being literature and food as the health literature, by examining the way consumers think about natural (versus man-made) food using user generated content of Twitter, which has not been previously used.
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Huang Taiming, JingMao Ma, Li Zhang, Pan Hao, MingChen Feng, Wei Zeng and Changjie Ou
The purpose of this study is investigate the transient aerodynamic characteristics of high-speed vehicle with body roll motion under crosswind condition to improve aerodynamic…
Abstract
Purpose
The purpose of this study is investigate the transient aerodynamic characteristics of high-speed vehicle with body roll motion under crosswind condition to improve aerodynamic stability.
Design/methodology/approach
An overset mesh was used to simulate the rolling motion of the vehicle body. A wind tunnel experiment was conducted to validate the numerical method.
Findings
The results revealed that the vehicle’s aerodynamic characteristics changed periodically with the body’s periodic motion. In the absence of crosswind, the pressure distribution on the left and right sides of the vehicle body was symmetrical, and the speed streamline flowed to the rear of the vehicle in an orderly manner. The maximum aerodynamic lift observed in the transient simulation was −0.089, which is approximately 0.70 times that of the quasi-static simulation experiment. In addition, the maximum aerodynamic side force observed in the transient simulation was 0.654, which is approximately 1.25 times that of the quasi-static simulation experiment.
Originality/value
The aerodynamic load varies periodically with the vehicle body’s cyclic motion. However, the extreme values of the aerodynamic load do not occur when the vehicle body is at its highest or lowest position. This phenomenon is primarily attributed to the mutual interference of airflow viscosity and the hysteresis effect in the flow field, leading to the formation of a substantial vortex near the wheel. Consequently, the aerodynamic coefficient at each horizontal position becomes inconsistent during the periodic rolling of the vehicle body.
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Pan Hao, Yuchao Dun, Jiyun Gong, Shenghui Li, Xuhui Zhao, Yuming Tang and Yu Zuo
Organic coatings are widely used for protecting metal equipment and structures from corrosion. Accurate detection and evaluation of the protective performance and service life of…
Abstract
Purpose
Organic coatings are widely used for protecting metal equipment and structures from corrosion. Accurate detection and evaluation of the protective performance and service life of coatings are of great importance. This paper aims to review the research progress on performance evaluation and lifetime prediction of organic coatings.
Design/methodology/approach
First, the failure forms and aging testing methods of organic coatings are briefly introduced. Then, the technical status and the progress in the detection and evaluation of coating protective performance and the prediction of service life are mainly reviewed.
Findings
There are some key challenges and difficulties in this field, which are described in the end.
Originality/value
The progress is summarized from a variety of technical perspectives. Performance evaluation and lifetime prediction include both single-parameter and multi-parameter methods.