Xinping Xiao and Fuqin Li
The purpose of this paper is to deal with the ill‐conditioned problem for the non‐equigap GM(1,1) control model by using the method of multiple transformations.
Abstract
Purpose
The purpose of this paper is to deal with the ill‐conditioned problem for the non‐equigap GM(1,1) control model by using the method of multiple transformations.
Design/methodology/approach
Owing to noises and interferences from both inside and outside of the system, many control systems contain unequal intervals and sharp variation which may result in undesirable systems instability. In order to ensure the stability and efficiency of grey forecasting control model, the data transformation for a raw series is an important and useful method for enhancing accuracy and improving ill‐condition of the non‐equigap GM(1,1) model.
Findings
This paper discusses the quantitative relations between the multiple transformation and the parameters of the non‐equigap GM(1,1) model in detail, and studies the effect of the multiple transformation on the condition number of the non‐equigap GM(1,1) model.
Research limitations/implications
Accessibility and availability of data are the main limitations based on which model will be applied.
Practical implications
Choosing an appropriate multiple of transformation cannot only eliminate dimension, lessen computation and maintain high accuracy, but also largely reduce the condition number of the model and improve the ill‐condition of non‐equigap GM(1,1) model effectively.
Originality/value
This paper seems to be the first to discuss the stability problems for the non‐equigap GM(1,1) model.
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Jiaqi Liu, Haitao Wen, Rong Wen, Wenjue Zhang, Yun Cui and Heng Wang
To contribute to achieving the Sustainable Development Goals, this study aims to explore how to encourage innovative green behaviors among college students and the mechanisms…
Abstract
Purpose
To contribute to achieving the Sustainable Development Goals, this study aims to explore how to encourage innovative green behaviors among college students and the mechanisms behind the formation of green innovation behavior. Specifically, this study examines the influences of schools, mentors and college students themselves.
Design/methodology/approach
A multilevel, multisource study involving 261 students from 51 groups generally supported this study’s predictions.
Findings
Proenvironmental and responsible mentors significantly predicted innovative green behavior among college students. In addition, creative motivation mediated the logical chain among green intellectual capital, emotional intelligence and green innovation behavior.
Practical implications
The study findings offer new insights into the conditions required for college students to engage in green innovation. In addition, they provide practical implications for cultivating green innovation among college students.
Originality/value
The authors proposed and tested a multilevel theory based on the ability–motivation–opportunity framework. In this model, proenvironmental and responsible mentors, green intellectual capital and emotional intelligence triggered innovative green behavior among college students through creative motivation.
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Fuqin Yang, Dexing Hu, Qianhao Xiao and Shun Zhao
This paper aims to study line-contact elastohydrodynamic grease lubrication properties of surface-textured rollers as well as the effect of different crown widths (dw) on oil film…
Abstract
Purpose
This paper aims to study line-contact elastohydrodynamic grease lubrication properties of surface-textured rollers as well as the effect of different crown widths (dw) on oil film thickness under textured conditions.
Design/methodology/approach
The laser processing method was used to make the micro-texture on the surface of GCr15 steel rollers; lithium grease was used as the lubricant, and line-contact elastohydrodynamic grease lubrication experiments under pure sliding conditions were performed on light interference elastohydrodynamic-lubricated experimental table.
Findings
The results show that the line-contact elastohydrodynamic grease lubrication is closely related to the textured crown width of steel rollers. At low speeds and light loads, texturing has an inevitable inhibitory effect on the formation of the lubricating oil film, and the smaller the width of the crown area, the more obvious the inhibitory effect, which is not conducive to the improvement of the lubrication condition. At high speeds and high loads, the textured roller with dw = 1 mm has the largest oil film thickness and shows better lubrication performance.
Originality/value
At present, there is little research on the surface texture of line-contact friction pairs. This work explores the effect of different textured crown width on the lubricating properties of line-contact elastohydrodynamic grease lubrication by experiment. It provides a new theoretical basis for the subsequent practical application of surface texture technology.
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Ellen Efron Pimentel and Jinyun Liu
In this paper, we model histories of coresidence between two cohorts of urban Chinese couples, married during the Cultural Revolution and early market reform periods. Most…
Abstract
In this paper, we model histories of coresidence between two cohorts of urban Chinese couples, married during the Cultural Revolution and early market reform periods. Most research on coresidence pictures families cross‐sectionally, but nuclear households are a natural part of extended coresidence systems that prefer stem family arrangements. We study histories of coresidence to determine what predicts ever having coresided with the husband’s parents, comparing the predictive power of modernization theory to the impact of demographic change, the availability of household members, and the resources and needs of each generation. While married children’s needs for childcare do not propel them into coresidence, they strongly predict the likelihood of staying coresident.
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Fuqin Yang, Xiaojie Han and Mingqing Si
This paper aims to study the influence of three-column groove shell radius, ball radius, lubricating oil viscosity and elastic modulus on the thermal elastohydrodynamic…
Abstract
Purpose
This paper aims to study the influence of three-column groove shell radius, ball radius, lubricating oil viscosity and elastic modulus on the thermal elastohydrodynamic lubrication (TEHL) characteristics and optimisation of the ball-type tripod universal joint.
Design/methodology/approach
The point contact TEHL model of the joint was developed, and the multi-grid method was used to solve it. The influence of three-column groove shell radius, ball radius, lubricating oil viscosity and elastic modulus on the lubrication characteristics was analysed. Further, the optimisation of the joint TEHL performance was carried out by the Kriging approximation model combined with the multi-objective particle swarm optimisation (MOPSO) algorithm.
Findings
The research results show that increasing groove shell radius and ball radius can effectively increase the oil film thickness, and decrease the oil film pressure, as well as the temperature rise. Decreasing elastic modulus can reduce the oil film temperature rise and pressure, and increasing viscosity can effectively increase the oil film thickness. The optimised minimum oil film thickness increases by 33.23% and the optimised maximum oil film pressure and maximum temperature rise decrease by 11.92% and 28.87%, respectively. Furthermore, the relative error of each response output is less than 10%.
Originality/value
This study applies TEHL theory to the tribological research of the ball-type tripod universal joint, and the joint’s lubrication performance is improved greatly by the Kriging model and MOPSO algorithm, which provides an effective measure to raise the joint’s working efficiency.
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Rommel AlAli and Ali Al-Barakat
This research aims to investigate the attitudes of young children toward learning science in the early educational grades.
Abstract
Purpose
This research aims to investigate the attitudes of young children toward learning science in the early educational grades.
Design/methodology/approach
The study involved conducting interviews with seventy-three children attending institutions in Sharjah, United Arab Emirates. The structured interview method was employed to collect valuable data.
Findings
The findings of the interviews shed light on the inclination of young children to foster positive attitudes toward science education. These inclinations include the facilitation of knowledge acquisition that enables children to develop skills for applying scientific concepts in real-life contexts, the incorporation of hands-on activities both inside and outside the classroom, and the prioritization of child-centered approaches to learning.
Originality/value
This research aims to explore the attitudes of young children in early educational grades toward learning science. Interviews were conducted with seventy-three children in Sharjah, UAE, using a structured interview method. The findings highlight children’s inclination toward positive attitudes in science education, including the importance of knowledge acquisition for applying scientific concepts in real-life contexts, hands-on activities inside and outside the classroom, and child-centered learning approaches. Based on these findings, the study provides recommendations and conclusions to enhance science education experiences for young children.
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Xinping Xiao and Yayun Lu
The purpose of this paper is to simplify the computation of parameter estimation in the grey linear regression model and solve the problem that the development coefficient could…
Abstract
Purpose
The purpose of this paper is to simplify the computation of parameter estimation in the grey linear regression model and solve the problem that the development coefficient could not be computed in some sequence data, such as short‐term traffic flow.
Design/methodology/approach
Starting from the limitation that can be identified in the equation and analyzing the range using the method to estimate parameters, this paper researches the modelling mechanism and the other forms which are equivalent with the original form. At the same time, this paper gives an estimation method and gets the relationship in various forms and the relationship between the model and GM(1,1) model.
Findings
For the grey linear regression model, there exists a new method of parameter identification and three other forms as follows: the original form, the Whitenization equation and the connotation form.
Practical implications
The method of parameter identification exposed in the paper expanded the scope of the application of the grey linear regression model, and it can be used to model and forecast the urban road short‐time traffic flow.
Originality/value
This paper has solved some complicated problems such as the parameter estimation computation in the grey linear regression model. In addition, three kinds of representation forms of the model and its relationship between the model and GM(1,1) have also been presented. Finally, its application of the model in a short‐term traffic flow prediction has shown its superiority.
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Haifeng Fang, Yangyang Wei and Shuo Dong
Tactile sensation is an important sensory function for robots in contact with the external environment. To better acquire tactile information about objects, this paper aims to…
Abstract
Purpose
Tactile sensation is an important sensory function for robots in contact with the external environment. To better acquire tactile information about objects, this paper aims to propose a three-layer structure of the interdigital flexible tactile sensor.
Design/methodology/approach
The sensor consists of a bottom electrode layer, a middle pressure-sensitive layer and a top indenter layer. First, the pressure sensitive material, structure design, fabrication process and circuit design of the sensor are introduced. Then, the calibration and performance test of the designed sensor is carried out. Four functions are used to fit and calibrate the relationship between the output voltage of the sensor and the contact force. Finally, the contact force sensing test of different weight objects and the flexible test of the sensor are carried out.
Findings
The performance test results show that the sensitivity of the sensor is 0.93 V/N when it is loaded with 0–3 N and 0.23 V/N when it is loaded with 3–5 N. It shows good repeatability, and the cross-interference between the sensing units is generally low. The contact force sensing test results of different weight objects show that the proposed sensor performs well in contact force. Each part of the sensor is a flexible material, allowing the sensor to achieve bending deformation, so that the sensor can better perceive the contact signs of the grasped object.
Practical implications
The sensor can paste the surface of the paper robot’s gripper to measure the contact force of the grasping object and estimate the contour of the object.
Originality/value
In this paper, a three-layer interdigital flexible tactile sensor is proposed, and the structural parameters of the interdigital electrode are designed to improve the sensitivity and response speed of the sensor. The indenter with three shapes of the prism, square cylinder and hemisphere is preliminarily designed and the prism indenter with better conduction force is selected through finite element analysis, which can concentrate the external force in the sensing area to improve the sensitivity. The sensor designed in this paper can realize the measurement of contact force, which provides a certain reference for the field of robot tactile.