This paper aims to study the change rule of sintered iron friction properties under high temperature and establish the model to predict the friction coefficient.
Abstract
Purpose
This paper aims to study the change rule of sintered iron friction properties under high temperature and establish the model to predict the friction coefficient.
Design/methodology/approach
The morphological measurements of sintered iron material with four different oxidation degrees are carried out. A prediction model of friction coefficient in high temperature oxide growth stage for sintered iron material is established based on the theory of flash temperature and adhesion friction. The relationship between friction coefficient and the key parameters is found through the test fitting.
Findings
The surface topography changes with oxidative wear. The wear debris will be compacted and sintered again to form a composite oxide layer with the temperature increasing. The validity and accuracy of proposed model are tested using the friction coefficient and temperature experiments. Results are in reasonable agreement with those obtained using values of load commonly used.
Originality/value
The significance lies in the change mechanism of high temperature friction characteristic is clarified. Three friction stages related to temperature of dry friction are put forward for sintered iron, and a meaningful reference is provided by the established model for high-temperature performance design of sintered iron friction material.
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Yanzhong Wang, Chao Guo, Yuan Li and Guoxing Li
This study aims to establish a friction coefficient model relative to the rotation speed of a wet clutch engagement, which can predict friction coefficient under different stages…
Abstract
Purpose
This study aims to establish a friction coefficient model relative to the rotation speed of a wet clutch engagement, which can predict friction coefficient under different stages of slipping velocity and different load pressures. In particular, the model has been improved by accounting the speed effect for the perdition of wet friction-element boundary friction, which is significant for understanding the friction mechanisms and for supporting the development of more efficient and related products.
Design/methodology/approach
This research investigated the mechanism of wet friction in a wet clutch engagement. A mixed friction model is established based on the asperity model and Newton’s law of viscosity. To obtain a friction coefficient computed by the model, the normal load shared by both asperities and lubrication fluid needs to be determined. Therefore, rough surface contact mechanism is analysed; a surface topography model is established; and surface parameters are obtained by means of surface topography measurement and reconstruction. Finally, verification of the mixed friction model is achieved.
Findings
Friction will be generated by both the asperity contact and the lubrication film shear relative to the rotation speed. And, the higher the relative speed, the larger the shearing power of lubrication film. It is caused by decrease in contact area of asperity. Surface morphology of a sintered bronze friction disk was obtained by a Laser-Micro-Test. The predicted results by the established model show that the total friction coefficient slightly reduced and then increased suddenly with speed. The surface topography model is responsible for the nonlinear behaviour of the asperity friction. Results of the simulation model are in agreement with those of the wet clutch engagement experiments.
Originality/value
This research is original and it is supported by the national defence project. The wet friction element which is applied on tracked vehicles is analysed for the first time. Through the model, the trend of the friction coefficient can be more accurately predicted. The problem of the wet friction plate modelling difficult is solved by using the mixed friction model.
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Sahar Feili, H.R. Sabouhi, Hassan Sobhani and M. Traz
This study aims to propose a new scheme for designing a high-sensitivity optical biosensor. For this, two agents have been considered: reflection-type micro-resonators, which…
Abstract
Purpose
This study aims to propose a new scheme for designing a high-sensitivity optical biosensor. For this, two agents have been considered: reflection-type micro-resonators, which filter the noise of the pump, and coupled-ring reflectors (CRRs), which are coupled to partial reflecting elements in the bus waveguide to create Fano-resonance. These two agents improve the sensor sensitivity and have low-power optical switching/modulation.
Design/methodology/approach
The proposed model is based on the coupling of the CRRs with the Fabry–Pérot cavity. The slope of the Fano-resonance line shape and consequently the sensitivity of the proposed CRRs are higher than those of conventional microring resonators.
Findings
The proposed scheme has many characteristics: CRRs have been used to create a higher slope of the Fano-resonance line shape; the sensitivity of the sensor shows improvement on the basis of reflection-type micro-resonators and by the removal of the pump noise; the designed sensor has low-power optical switching/modulation; and the modeling and designing of a novel high-sensitivity resonator is based on coupling the CRRs with the Fabry–Pérot cavity.
Originality/value
This study has proposed a new scheme for designing a high-sensitivity optical biosensor. This method is based on the improvement of the sensitivity by two agents: reflection-type micro-resonators, which filter the noise of the pump, and coupled-ring reflectors, which are coupled to partial reflecting elements in the bus waveguide to create Fano-resonance.
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Guo Chao Peng and Miguel Nunes
The purpose of this paper is to propose a systematic and customisable framework, titled the 9D approach, aiming to evaluate the enterprise resource planning (ERP) systems as well…
Abstract
Purpose
The purpose of this paper is to propose a systematic and customisable framework, titled the 9D approach, aiming to evaluate the enterprise resource planning (ERP) systems as well as to identify potential socio-technical problems, misfits and deficiencies that can cause ERP failure during the system post-implementation phase.
Design/methodology/approach
The proposed 9D ERP evaluation framework includes nine dimensions and 85 evaluation criteria. This theoretical framework is then used in a six-step evaluation process based on a mixed-methods design. A case study involving a large-size private company in China was used as an exemplification to illustrate how the proposed 9D approach can be applied in practices.
Findings
The findings of the study clearly demonstrated that after the ERP “go-live” point, companies still experience many challenges and problems in the post-implementation phase. These problems can be located in very diverse organisational, systemic and personnel aspects of the company, as well as across different functional areas and organisational levels. The proposed 9D approach was demonstrated to be an efficient and systematic tool to investigate and explore such ERP problems in an in-depth level within the organisational context.
Research limitations/implications
This study contributes to the theory of IS evaluation in general, and provides valuable insights into the ERP post-implementation evaluation in particular.
Practical implications
The proposed ERP evaluation approach forms a sound base for continuous ERP improvement and contributes to sustain seamless alignment between ERP and its organisational context. The customisable feature of the framework offers flexibility and enables its use by companies of all sizes, any sector, and any country.
Originality/value
To the best of the researchers’ knowledge, this is the most extensive and comprehensive framework for the post-evaluation of ERPs proposed hitherto. The need for this new framework was grounded on the argumentation of the drawbacks of existing ERP measurement and evaluation studies that simply focus on success rather than the more critical failure factors.
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Lan Chu, Chao Guo, Qing Zhang, Qing Wang, Yiwen Ge, Mingyang Hao and Jungang Lv
This study aims to using Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy and scanning electron microscope/energy dispersive Xray spectrometer to identify…
Abstract
Purpose
This study aims to using Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy and scanning electron microscope/energy dispersive Xray spectrometer to identify different automotive coatings for forensic purpose.
Design/methodology/approach
Two four-layered samples in a hit-and-run case were compared layer by layer with three different methods. FTIR spectroscopy was used to primarily identify the organic and inorganic compositions. Raman spectrum and scanning electron microscope/energy dispersive Xray spectrometer (SEM-EDS) were further used to complement the FTIR results.
Findings
Two weak and tiny peaks in one layer found between two samples by FTIR, Raman microscope and SEM-EDS verified the result of differences. The study used the three instruments in combination and found it’s effective in sensing coatings, especially in the inorganic additives.
Research limitations/implications
Using these three instruments in combination is more accurate than individually in multilayered coating analysis for forensic purpose.
Practical implications
The three different instruments all present unique information on the composition, and provided similar and mutually verifiable results on the two samples.
Originality/value
With this method, scientists could identify and discriminate important coating evidences with tiny but characteristic differences.
Details
Keywords
Shuyang Li, Guo Chao Peng and Fei Xing
Big data is a key component to realise the vision of smart factories, but the implementation and usage of big data analytical tools in the smart factory context can be fraught…
Abstract
Purpose
Big data is a key component to realise the vision of smart factories, but the implementation and usage of big data analytical tools in the smart factory context can be fraught with challenges and difficulties. The purpose of this paper is to identify potential barriers that hinder organisations from applying big data solutions in their smart factory initiatives, as well as to explore causal relationships between these barriers.
Design/methodology/approach
The study followed an inductive and exploratory nature. Ten in-depth semi-structured interviews were conducted with a group of highly experienced SAP consultants and project managers. The qualitative data collected were then systematically analysed by using a thematic analysis approach.
Findings
A comprehensive set of barriers affecting the implementation of big data solutions in smart factories had been identified and divided into individual, organisational and technological categories. An empirical framework was also developed to highlight the emerged inter-relationships between these barriers.
Originality/value
This study built on and extended existing knowledge and theories on smart factory, big data and information systems research. Its findings can also raise awareness of business managers regarding the complexity and difficulties for embedding big data tools in smart factories, and so assist them in strategic planning and decision making.
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Chao Guo, Huai‐Ning Wu, Biao Luo and Lei Guo
The air‐breathing hypersonic vehicle (AHV) includes intricate inherent coupling between the propulsion system and the airframe dynamics, which results in an intractable nonlinear…
Abstract
Purpose
The air‐breathing hypersonic vehicle (AHV) includes intricate inherent coupling between the propulsion system and the airframe dynamics, which results in an intractable nonlinear system for the controller design. The purpose of this paper is to propose an H∞ control method for AHV based on the online simultaneous policy update algorithm (SPUA).
Design/methodology/approach
Initially, the H∞ state feedback control problem of the AHV is converted to the problem of solving the Hamilton‐Jacobi‐Isaacs (HJI) equation, which is notoriously difficult to solve both numerically and analytically. To overcome this difficulty, the online SPUA is introduced to solve the HJI equation without requiring the accurate knowledge of the internal system dynamics. Subsequently, the online SPUA is implemented on the basis of an actor‐critic structure, in which neural network (NN) is employed for approximating the cost function and a least‐square method is used to calculate the NN weight parameters.
Findings
Simulation study on the AHV demonstrates the effectiveness of the proposed H∞ control method.
Originality/value
The paper presents an interesting method for the H∞ state feedback control design problem of the AHV based on online SPUA.
Details
Keywords
Tian-Chao Guo and Zhi-Chao Cheng
Although novel posting is a universal phenomenon in virtual communities (VCs), few studies have addressed the benefits of novel posting for group members. The purpose of this…
Abstract
Purpose
Although novel posting is a universal phenomenon in virtual communities (VCs), few studies have addressed the benefits of novel posting for group members. The purpose of this paper is to identify the social and psychological outcomes of novel posting, particularly whether and how sense of belonging can be produced by it. Sense of belonging implies an individual’s integration or assimilation into virtual groups.
Design/methodology/approach
To assess the theoretical model, a survey was administered in an internet discussion community (Baidu Post Bar in China), and structural equation modeling was then used to test the model.
Findings
Novel posting can produce social and psychological outcomes, such as social interaction ties, group-based self-esteem and sense of belonging. Novel posting is an individualized behavior, which some studies consider to conflict with sense of belonging; however, via the mediating effects of social interaction ties and group-based self-esteem, sense of belonging can also arise based on novel posting.
Practical implications
VC operators should focus on differentiating between irrational posts and novel posts and encourage the latter. Additionally, to satisfy members’ needs, VC operators should strengthen the degree of social interaction ties and members’ self-esteem by providing attractive topics and virtual rankings.
Originality/value
This study contributes to a theoretical understanding of the social and psychological outcomes of novel posting and, more importantly, whether and how sense of belonging arises on the basis of individualized behavior.
Details
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The popular CFD code FDS is adopted to predict the thermal behaviors of steel columns exposed to localized fires. Two real localized fire tests (one surrounded fire test that the…
Abstract
The popular CFD code FDS is adopted to predict the thermal behaviors of steel columns exposed to localized fires. Two real localized fire tests (one surrounded fire test that the column is inside the fire source and one adjacent fire test that the column is adjacent to the fire source) are modeled in FDS. The effects of input parameters such as grid size and number of solid angles on the accuracy of the numerical results have been investigated. Experimental results concerning heat fluxes and temperatures are compared with the numerical results. Good agreements between the predicted and measured results are found in surrounded fire case, whilst acceptable predictions are given in adjacent fire case.
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Linhao Ouyang, Zijian Zhang, Xiaoling Huang and Shi Xie
The purpose of this study is to restore the spatial distribution of overseas remittance businesses in Shantou during the 1940s. It explores various socioeconomic factors that…
Abstract
Purpose
The purpose of this study is to restore the spatial distribution of overseas remittance businesses in Shantou during the 1940s. It explores various socioeconomic factors that influenced the concentration of local remittance business investment in real estate. By reconstructing the spatial distribution of remittance business activities in Shantou, this study hopes to lay a foundation for further analysis of the business strategies of Chaoshan merchants.
Design/methodology/approach
This research draws on information from the published Swatow Guide, archival sources and cadastral maps to identify the location of remittance enterprises and the native place and overseas networks of property owners.
Finding
This study reveals that the spatial distribution of the remittance enterprises was determined by the native place origins of local property owners, and that the inflow of overseas Chinese capital contributed to real estate development in Shantou.
Research limitations/implications
Despite the limited access to Chinese official archives, this paper manages to identify several building blocks and neighbors in Shantou for spatial analysis.
Practical implications
This study is the first attempt to use the geographical information system (GIS) method in Chinese urban history research and hopes to establish a larger historical database of Shantou as a sample for comparison.
Originality/value
This investigation advances the spatial study of urban history and overseas Chinese remittances in the maritime society of South China.