Zhang Zhengyu, Ding Yucheng and Hong Jun
A new method of hollowing rapid prototype models based on STL models and their cross‐sectional contours is presented to meet the demands of hollowed prototypes in casting and…
Abstract
A new method of hollowing rapid prototype models based on STL models and their cross‐sectional contours is presented to meet the demands of hollowed prototypes in casting and rapid prototype manufacturing. Offsetting along the Z‐axis and cross‐sectional contour offsetting are employed to perform the hollowing operation. The process performs two‐dimensional Boolean operations on the polygons made by the offset contours of cross‐sectional contours instead of three‐dimensional offsetting of the STL models. This hollowing operation is especially suitable for hollowing STL models with free‐form surfaces. Detailed algorithms are described to generate the correct offset contours of an STL model. Adopting this method, the hollowing process is dramatically simplified and becomes more efficient. This method has been verified by practical case studies, and it is proved that this simplified hollowing operation can reduce the prototype build time and cost.
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Yiqing Wang, Wanhua Zhao, Yucheng Ding, Zhongyun He and Bingheng Lu
The purpose of this paper is to detect and control the liquid‐level of stereolithography apparatus precisely.
Abstract
Purpose
The purpose of this paper is to detect and control the liquid‐level of stereolithography apparatus precisely.
Design/methodology/approach
A brightness‐variable laser source is adopted to remove the computational error of divider and a closed‐loop circuit is set to measure the terminal voltage directly proportional to the output current of photosensitive devices. It employs a sinking‐block device to control the liquid‐level.
Findings
The precise calibration result of this detecting device indicates that the resolution of the liquid‐level detection can reach ±1.5 μm.
Originality/value
This sinking‐block style liquid‐level control device can allow for the liquid‐level wave reduced from ±45 to ±15 μm.
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Yiqing Wang, Yucheng Ding, Wanhua Zhao, Zhongyun He and Bingheng Lu
The purpose of this paper is to show how to precisely control the liquid resin coating thickness in stereolithography (SL).
Abstract
Purpose
The purpose of this paper is to show how to precisely control the liquid resin coating thickness in stereolithography (SL).
Design/methodology/approach
A vacuum adsorption coating equipment and technology are developed to precisely control the liquid resin coating thickness in SL. Dual‐electrode device is used, so adsorption can be precisely controlled and the electrode polarization can be avoided.
Findings
It turns out that the apparatus can control coating thickness effectively, and thickness uniformity is increased remarkably, which induces the standard deviation thickness decrease from 0.00547 to 0.00243 mm, and efficiency of rapid prototyping production increase by 53 percent.
Originality/value
The paper demonstrates that the apparatus can control coating thickness effectively.
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Yucheng Zhang, Zhongwei Hou, Xingxing Zhou, Yumeng Yue, Siqi Liu, XiaoXiao Jiang and Ling Li
Despite recent organizational behavior studies have witnessed considerable progress in abusive supervision research; some demerits for both theory and methodology still remain in…
Abstract
Purpose
Despite recent organizational behavior studies have witnessed considerable progress in abusive supervision research; some demerits for both theory and methodology still remain in the past years. To clarify the current state of knowledge in the field, this study aims to analyze the current state of theories and methods on abusive supervision and provides a detailed future research agenda.
Design/methodology/approach
This paper conducted a literature review for both theory and methodology of the abusive supervision research using a content analysis of 134 publications.
Findings
For the theory part, this paper summarized the theories that had been applied to explain the relationship between abusive supervision and its consequences as well as antecedents. For the methodology part, this paper outlined some critical issues regarding country of origin, research design, measurement, analysis strategy and also summarized with a discussion of the relationship between methodological issues and article impact. Finally, this paper concluded by presenting an agenda for future abusive supervision research regarding both theory and methodology.
Originality/value
First, this paper summarizes the main theories, antecedents and consequences often used in abusive supervision research to allow scholars to carry out theoretically driven research investigating abusive supervision in the future. Second, through a content analysis of the methods sections of abusive supervision research in the samples (i.e. country of origin, research design, measurement and analytical procedures), this paper identified the potential reasons underlying the inconsistency in the conclusions of abusive supervision research and provide some guidance for future empirical studies. Third, based on the qualitative review, this paper provides an agenda for future research investigating abusive supervision by developing a content-specific theoretical framework to benchmark abusive supervision research against other research related to leadership and offers an accurate response to scholars’ criticisms of abusive supervision research.
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Yucheng Shi, Deren Kong and Xuejiao Ma
The purpose of this study is to clarify the mechanism of ambient and transient temperature effects on piezoelectric pressure sensors, and to propose corresponding compensation…
Abstract
Purpose
The purpose of this study is to clarify the mechanism of ambient and transient temperature effects on piezoelectric pressure sensors, and to propose corresponding compensation measures. The temperature of the explosion field has a significant influence on the piezoelectric sensor used to measure the shock wave pressure. For accurate shock wave pressure measurement, based on the actual piezoelectric pressure sensors used in the explosion field, the effects of ambient and transient temperatures on the sensor should be studied.
Design/methodology/approach
The compensation method of the ambient temperature is discussed according to the sensor size and material. The theoretical analysis method of the transient temperature is proposed. For the transient temperature conduction problem of the sensor, the finite element simulation method of structure-temperature coupling is used to solve the temperature distribution of the sensor and the change in the contact force on the quartz crystal surface under the step and triangle temperatures. The simulation results are highly consistent with the theory.
Findings
Based on the analysis results, a transient temperature control method is proposed, in which 0.5 mm thick lubricating silicone grease is applied to the sensor diaphragm, and 0.2 mm thick fiberglass cloth is wrapped around the sensor side. Simulation experiments are carried out to verify the feasibility of the control method, and the results show that the control method effectively suppresses the output of the thermal parasitic.
Originality/value
The above thermal protection methods can effectively improve the measurement accuracy of shock wave pressure and provide technical support for the evaluation of the power of explosion damage.
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Minglei Hu, Kunjie Dai, Wei Zhang, Ke Xu, Jingkun Shi, Xiaoqian Fu, Yucheng Ji and Chaofang Dong
This study aims to investigate the crevice corrosion behavior of carbon steel in neutral/alkaline environments utilizing a transient multi-physics field model.
Abstract
Purpose
This study aims to investigate the crevice corrosion behavior of carbon steel in neutral/alkaline environments utilizing a transient multi-physics field model.
Design/methodology/approach
The crevice corrosion of carbon steel with different solution pH and crevice width was modeled, incorporating mass transfer, homogeneous phase and localized electrochemical reactions. The extent of crevice corrosion was evaluated by the geometric deformation of the model mesh. The hydro-chemical state inside the crevice was discussed through the Cl− concentration and potential distribution of the solution.
Findings
Results revealed that the formation of pitting corrosion near the crevice mouth was accelerated in a neutral solution. When pH = 8 and pH = 9, the carbon steel matrix was dissolved and the Cl− content within the solution was significantly reduced due to the higher concentration of hydroxide ions (OH−).
Originality/value
The crevice corrosion behavior of carbon steel in neutral/alkaline environments is closely associated with solution pH rather than the crevice width. The inhibition of crevice corrosion in alkaline environments was proved by finite element simulation. These findings provide valuable insights that can be applied in engineering applications to prevent and mitigate crevice corrosion in neutral/alkaline environments.
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Luya Yang, Xinbo Huang, Yucheng Ren, Qi Han and Yanchen Huang
In the process of continuous casting and rolling of steel plate, due to the influence of rolling equipment and process, there are scratches, inclusions, patches, scabs and pitted…
Abstract
Purpose
In the process of continuous casting and rolling of steel plate, due to the influence of rolling equipment and process, there are scratches, inclusions, patches, scabs and pitted surfaces on the surface of steel plate, which will not only affect the corrosion resistance, wear resistance and fatigue strength of steel plate but also may cause production accidents. Therefore, the detection of steel plate surface defect must be strengthened to ensure the production quality of steel plate and the smooth development of industrial construction.
Design/methodology/approach
(1) A steel plate surface defect detection technology based on small datasets is proposed, which can detect multiple surface defects and fill in the blank of scab defect detection. (2) A detection system based on intelligent recognition technology is built. The steel plate images are collected by the front-end monitoring device, then transmitted to the back-end monitoring center and processed by the embedded intelligent algorithms. (3) In order to reduce the impact of external light on the image, an improved Multi-Scale Retinex (MSR) enhancement algorithm based on adaptive weight calculation is proposed, which lays the foundation for subsequent object segmentation and feature extraction. (4) According to the different factors such as the cause and shape, the texture and shape features are combined to classify different defects on the steel plate surface. The defect classification model is constructed and the classification results are recorded and stored, which has certain application value in the field of steel plate surface defect detection. (5) The practicability and effectiveness of the proposed method are verified by comparison with other methods, and the field running tests are conducted based on the equipment commissioning field of China Heavy Machinery Institute.
Findings
When applied to small dataset, the precision of the proposed method is 94.5% and the time is 23.7 ms. In order to compare with deep learning technology, after expanding the image dataset, the precision and detection time of this paper are 0.948 and 24.2 ms, respectively. The proposed method is superior to other traditional image processing and deep learning methods. And the field recognition precision is 91.7%.
Originality/value
In brief, the steel plate surface defect detection technology based on computer vision is effective, but the previous attempts and methods are not comprehensive and the accuracy and detection speed need to be improved. Therefore, a more practical and comprehensive technology is developed in this paper. The main contributions are as follows: (1) A steel plate surface defect detection technology based on small datasets is proposed, which can detect multiple surface defects and fill in the blank of scab defect detection. (2) A detection system based on intelligent recognition technology is built. The steel plate images are collected by the front-end monitoring device, then transmitted to the back-end monitoring center and processed by the embedded intelligent algorithms. (3) In order to reduce the impact of external light on the image, an improved MSR enhancement algorithm based on adaptive weight calculation is proposed, which lays the foundation for subsequent object segmentation and feature extraction. (4) According to the different factors such as the cause and shape, the texture and shape features are combined to classify different defects on the steel plate surface. The defect classification model is constructed and the classification results are recorded and stored, which has certain application value in the field of steel plate surface defect detection. (5) The practicability and effectiveness of the proposed method are verified by comparison with other methods, and the field running tests are conducted based on the equipment commissioning field of China Heavy Machinery Institute.
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Chad Albrecht, Victor Morales, Jack Kristian Baldwin and Steven Deron Scott
The paper aims to report on the single largest peer-to-peer lending scandal in the history of China. The authors provide details on how the case was perpetrated. The authors also…
Abstract
Purpose
The paper aims to report on the single largest peer-to-peer lending scandal in the history of China. The authors provide details on how the case was perpetrated. The authors also provide details as to how investors were fraudulently manipulated in the scam. Finally, the authors provide updates on recent regulation in China in the peer-to-peer lending industry.
Design/methodology/approach
This is a theoretical paper that provides a better understanding of both Ponzi schemes and fraudulent practices in the peer-to-peer industry.
Findings
While the Ponzi scheme has been around for many years, fraud perpetrators continue to find new ways to use the scheme to manipulate and take advantage of investors. The case of Ezubao provides important insight for both regulators, academics, investors and financial advisors.
Originality/value
Ezubao, a start-up in an industry with little to no regulation, provides a textbook example of common fraud symptoms (or red flags). The deception was enacted through Ezubao’s bold advertising scheme and falsified appearance of success and government support. This was enough to brilliantly deceive over 900,000 susceptible investors. While Ezubao was one of the first peer-to-peer lending scandals to be uncovered, it certainly will not be the last.
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Wei Chen, Yucheng Ma, Xingyu Liu, Enguang Xu, Wenlong Yang, Junhong Jia, Rui Lou, Chaolong Zhu, Chenjing Wu and Ziqiang Zhao
The purpose of this paper is to improve the mechanical and tribological properties of Si3N4 ceramics and to make the application of Si3N4 ceramics as tribological materials more…
Abstract
Purpose
The purpose of this paper is to improve the mechanical and tribological properties of Si3N4 ceramics and to make the application of Si3N4 ceramics as tribological materials more extensive.
Design/methodology/approach
Si3N4-based composite ceramics (SN-2L) containing nitrogen-doped graphene quantum dots (N-GQDs) were prepared by hot press sintering process through adding 2 Wt.% nanolignin as precursor to the Si3N4 matrix, and the dry friction and wear behaviors of Si3N4-based composite against TC4 disc were performed at the different loads by using pin-on-disc tester.
Findings
The friction coefficients and wear rates of SN-2L composite against TC4 were significantly lower than those of the single-phase Si3N4 against TC4 at the load range from 15 to 45 N. At higher load of 45 N, SN-2L/TC4 pair presented the lowest friction coefficient of 0.25, and the wear rates of the pins and discs were as low as 1.76 × 10−6 and 2.59 × 10−4mm3/N·m. The low friction and wear behavior could be attributed to the detachment of N-GQDs from the ceramic matrix to the worn surface at the load of 30 N or higher, and then an effective lubricating film containing N-GQDs, SiO2, TiO2 and Al2SiO5 formed in the worn surface. While, at the same test condition, the friction coefficient of the single-phase Si3N4 against TC4 was at a range from 0.45 to 0.58. The spalling and cracking morphology formed on the worn surface of single-phase Si3N4, and the wear mechanism was mainly dominated by adhesive and abrasive wear.
Originality/value
Overall, a high-performance green ceramic composite was prepared, and the composite had a good potential for application in engineering tribology fields (such as aerospace bearings).
Peer review
The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-05-2024-0161/
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Rasoul Mehdikhani and Changiz Valmohammadi
The purpose of this paper is to investigate the impact of strategic collaboration (SC) on sustainable supply chain management (SSCM), considering the mediating role of internal…
Abstract
Purpose
The purpose of this paper is to investigate the impact of strategic collaboration (SC) on sustainable supply chain management (SSCM), considering the mediating role of internal knowledge sharing (IKS) and external knowledge sharing (EKS).
Design/methodology/approach
The study population consisted of experts associated with the supply chain in the automotive, food, clothing, pharmaceuticals and chemicals industries. After reviewing the literature, a conceptual framework was developed and applied using a structural equation modeling approach. In this study, samples with 271 observations were collected from manufacturing and servicing companies in Iran.
Findings
The results showed that SC in the supply chain has a positive impact on the IKS and EKS and SSCM. IKS and EKS have a positive impact on SSCM. Also, the results showed that IKS and EKS fully mediate in the relationship between SC and SSCM.
Research limitations/implications
This study has been done in the context of Iran, so caution should be taken to generalize the results.
Originality/value
The findings of the study contribute to the knowledge of the managers and policy makers in achieving SSCM. The results provide the important environmental and social concepts regarding the sustainability of supply chain using SC and IKS and EKS.