Kankan Ji, Xingquan Zhang, Shubao Yang, Liping Shi, Shiyi Wang and Yuguo Wu
The purpose of this paper is to evaluate surface integrity of quenched steel 1045 ground drily by the brazed cubic boron nitride (CBN) grinding wheel and the black SiC wheel…
Abstract
Purpose
The purpose of this paper is to evaluate surface integrity of quenched steel 1045 ground drily by the brazed cubic boron nitride (CBN) grinding wheel and the black SiC wheel, respectively. Surface integrity, including surface roughness, sub-surface hardness, residual stresses and surface morphology, was investigated in detail, and the surface quality of samples ground by two grinding wheels was compared.
Design/methodology/approach
In the present work, surface integrity of quenched steel 1045 machined by the CBN grinding wheel and the SiC wheel was investigated systematically. All the specimens were machined with a single pass in the down-cutting mode of dry condition. Surface morphology of the ground specimen was observed by using OLYMPUS BX51M optical microscopy. Surface roughness of seven points was measured by using a surface roughness tester at a cut-off length of 1.8 mm and the measurement traces were perpendicular to the grinding direction. Sub-surface micro-hardness was measured by using HVS-1000 digital micro-hardness tester after the cross-section surface was polished. The residual stress was tested by using X-350A X-ray stress analyzer.
Findings
When the cut depth is increased from 0.01 to 0.07 mm, the steel surface machined by the CBN wheel remains clear grinding mark, lower roughness, higher micro-hardness and higher magnitude of compressive stress and fine microstructure, while the surface machined by the SiC grinding wheel becomes worse with increasing of cut depth. The value of micro-hardness decreases, and the surface roughness increases, and the surface compressive stress turns into tensile stress. Some micro-cracks and voids occur when the sample is processed by the SiC grinding wheel with cut depth 0.07 mm.
Originality/value
In this paper, the specimens of quenched steel 1045 were machined by the CBN grinding wheel and the SiC wheel with various cutting depths. The processing quality resulted from the CBN grinding wheel is better than that resulted from the SiC grinding wheel.
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Yezhong Fang, Xiaotian Ji, Xingquan Zhang, Jun Wang, Bin Chen, Shiwei Duan, Jinyu Tong, Guangwu Fang and Shanbao Pei
The purpose of this paper is to investigate the dynamic forming process of the micro dent fabricated by laser shock processing on 2024-T3 aluminum alloy. The effect of laser pluse…
Abstract
Purpose
The purpose of this paper is to investigate the dynamic forming process of the micro dent fabricated by laser shock processing on 2024-T3 aluminum alloy. The effect of laser pluse energy on the deformation of micro dent was also discussed in detail.
Design/methodology/approach
It uses finite element analysis method and the corresponding laser shocking experiment.
Findings
The results demonstrate that the dynamic formation process of micro dent lasts longer in comparison with the shock wave loading time, and the depths of micro dents increase with the increasing laser energy. In addition, laser shocking with higher energy can result in more obvious pileup occurred at the outer edge of micro dent.
Originality/value
Surface micro dents can serve as fluid reservoirs and traps of the wear debris, which can decrease the effects of the wear and friction in rolling and sliding interfaces. The investigations can not only be propitious to comprehensively understand the forming mechanism of laser-shocked dent, but also be beneficial to get sight into the residual stress field induced by laser shocking.
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Min Li, Hangxuan Liu, Xingquan Zhang, Hengji Yang, Lisheng Zuo, Ziyu Wang, Shiwei Duan and Song Shu
The purpose of this paper is to investigate the effect of laser peening (LP) on mechanical and wear properties of 304 stainless steel sheet.
Abstract
Purpose
The purpose of this paper is to investigate the effect of laser peening (LP) on mechanical and wear properties of 304 stainless steel sheet.
Design/methodology/approach
Three-dimensional morphology, micro-hardness and micro-structure of shocked samples were tested. The wear amount, wear track morphology and wear mechanism were also characterized under dry sliding wear using Al2O3 ceramics ball.
Findings
The LP treatment generates deformation twins that contribute to the grain refinement and hardness increase. The wear test displays that the wear mechanism of samples is mainly abrasive wear and oxidation wear at 10 N load. While at 30 N, the delamination and adhesion areas of treated sample are reduced visibly compared to untreated ones.
Originality/value
This study specifically investigates the mechanical and wear properties of 304 stainless steel after the direct action of LP on its surface, which shows an effective improvement on the wear resistance. For example, the wear loss of processed sample is reduced by 19% at 30 N, the friction coefficient decreases from 0.4714 to 0.4308 and the groove depth is reduced from 78.1 to 74.4 µm under same condition.
Peer review
The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-01-2024-0007/
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Xingquan Wang, Xiuyuan Lu, Wei Chen, Fengpeng Wang, Jun Huang, Lingli Liu, Mengchao Li and Kui Lin
This paper aims to improve the general circuit of driving and protection based on insulated gate bipolar transistor (IGBT) in dielectric barrier discharge power supply by…
Abstract
Purpose
This paper aims to improve the general circuit of driving and protection based on insulated gate bipolar transistor (IGBT) in dielectric barrier discharge power supply by designing a novel half-bridge inverter circuit with discrete components.
Design/methodology/approach
With one SG3524 chip, the structure based on discrete components is used to design the IGBT drive circuit. The driving waveform is isolated and sent out by photo-coupler 6N137. The protection circuit is realized by Hall sensor directly detecting the main circuit current, supplemented by a few components, including diodes, resistors, capacitors and triodes. It improves the reliability of the protection circuit.
Findings
In the driving circuit, the phase difference of signals from two channels are 180°. Moreover, when the duty cycle is set at 40%, it can ensure sufficient pulse width modulation response time. In the protection circuit, when over-current occurs, an intermittent output signal is automatically sent out. Furthermore, the over-current response time can be controlled independently. The peak voltage can be adjusted continuously from 0 to 30 kV with its frequency from 8 to 25 kHz and the power output up to 150 W.
Originality/value
The novel circuit of driving and protection makes not only its structure simpler and easier to be realized but also key parameters, such as frequency, the duty cycle and the driving voltage, continuously adjustable. Moreover, the power supply is suitable for other discharges such as corona discharge and jet discharge.
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Yunan Chen, Ivan Sun, Yuning Wu, Zhe Chao and Yuping Liu
The main purpose of this study is to examine the direct relationship between police officers' perceived technology utilization and their perception of external procedural…
Abstract
Purpose
The main purpose of this study is to examine the direct relationship between police officers' perceived technology utilization and their perception of external procedural injustice, as well as the indirect relationship through perceived self-legitimacy.
Design/methodology/approach
This study used survey data collected from 1,944 police officers in a northern Chinese province. Structural equation modeling (SEM) was performed to assess the direct and indirect associations between technology utilization and external procedural injustice.
Findings
Technology efficacy was negatively associated with external procedural injustice and positively associated with both self-legitimacy and public-defined legitimacy. Furthermore, officers’ self-perceived legitimacy is negatively associated with their support for procedurally unjust behaviors, while officers’ perception of public-defined legitimacy, unexpectedly, is positively related to their endorsement of procedural injustice. Conversely, technology difficulty was positively related to external procedural injustice and negatively associated with public-defined legitimacy.
Originality/value
The present study represents a first attempt to link technology utilization to external procedural injustice in the policing literature. This study provides needed evidence to support the importance role of technology utilization in shaping police officers’ occupational attitudes toward themselves and the public in an authoritarian country.
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This work can be used as a building block in other settings such as GPU, Map-Reduce, Spark or any other. Also, DDPML can be deployed on other distributed systems such as P2P…
Abstract
Purpose
This work can be used as a building block in other settings such as GPU, Map-Reduce, Spark or any other. Also, DDPML can be deployed on other distributed systems such as P2P networks, clusters, clouds computing or other technologies.
Design/methodology/approach
In the age of Big Data, all companies want to benefit from large amounts of data. These data can help them understand their internal and external environment and anticipate associated phenomena, as the data turn into knowledge that can be used for prediction later. Thus, this knowledge becomes a great asset in companies' hands. This is precisely the objective of data mining. But with the production of a large amount of data and knowledge at a faster pace, the authors are now talking about Big Data mining. For this reason, the authors’ proposed works mainly aim at solving the problem of volume, veracity, validity and velocity when classifying Big Data using distributed and parallel processing techniques. So, the problem that the authors are raising in this work is how the authors can make machine learning algorithms work in a distributed and parallel way at the same time without losing the accuracy of classification results. To solve this problem, the authors propose a system called Dynamic Distributed and Parallel Machine Learning (DDPML) algorithms. To build it, the authors divided their work into two parts. In the first, the authors propose a distributed architecture that is controlled by Map-Reduce algorithm which in turn depends on random sampling technique. So, the distributed architecture that the authors designed is specially directed to handle big data processing that operates in a coherent and efficient manner with the sampling strategy proposed in this work. This architecture also helps the authors to actually verify the classification results obtained using the representative learning base (RLB). In the second part, the authors have extracted the representative learning base by sampling at two levels using the stratified random sampling method. This sampling method is also applied to extract the shared learning base (SLB) and the partial learning base for the first level (PLBL1) and the partial learning base for the second level (PLBL2). The experimental results show the efficiency of our solution that the authors provided without significant loss of the classification results. Thus, in practical terms, the system DDPML is generally dedicated to big data mining processing, and works effectively in distributed systems with a simple structure, such as client-server networks.
Findings
The authors got very satisfactory classification results.
Originality/value
DDPML system is specially designed to smoothly handle big data mining classification.
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Yi Nie, Lin Luo and Xiulin Geng
Green funds represent a hybrid approach that integrates both environmental and financial considerations. Firms also strive to balance social benefits with economic performance…
Abstract
Purpose
Green funds represent a hybrid approach that integrates both environmental and financial considerations. Firms also strive to balance social benefits with economic performance. This study aims to analyze how green fund shareholdings impact firms’ dual performance and explores the underlying mechanisms and boundary conditions.
Design/methodology/approach
This study uses a sample of A-share companies listed on China’s exchanges from 2008 to 2022. A fixed effects model is used to assess the dual value of green funds in enhancing both environmental and financial performance while also exploring viable pathways to achieve a “win-win” outcome.
Findings
Green fund shareholdings significantly enhance both financial and environmental performance, with corporate reputation and corporate transparency acting as mediators. Media oversight and executive compensation positively moderate the relationship between green fund shareholdings and dual performance. In competitive industries, the influence of green fund shareholdings on environmental performance is more pronounced than their effect on financial performance. In the context of politically connected firms, green fund shareholdings have a reduced impact on financial performance, with no significant difference in environmental performance. In addition, the impact of green funds on ownership structure is heterogeneous, promoting dual performance in private firms but not in state-owned enterprises.
Originality/value
This study enhances the understanding of green funds’ dual investment logic, provides deeper insights into their role in fostering sustainable corporate development and extends the application of institutional logic in enterprise management.