Hailong Zhao, Lirong Luo, Fangwei Guo, Xiaofeng Zhao and Ping Xiao
The purpose of this paper is to investigate the tribological performance of Cr3C2–NiCr–Mo–BaF2 composite sliding against a Si3N4 ball at high temperatures.
Abstract
Purpose
The purpose of this paper is to investigate the tribological performance of Cr3C2–NiCr–Mo–BaF2 composite sliding against a Si3N4 ball at high temperatures.
Design/methodology/approach
A Cr3C2–NiCr composite and a Cr3C2–NiCr–Mo–BaF2 composite were prepared using spark plasma sintering. Tribological properties of the composites were investigated using a ball-on-disk type tribotester. The relationships among the microstructure, wear mechanism and tribological performance were determined by analyzing the wear track morphologies and the glaze layer’s phase composition.
Findings
The wear rate of the Cr3C2–NiCr–Mo–BaF2 composite was approximately one order of magnitude lower than that of the Cr3C2–NiCr composite from 700°C to 900°C when sliding against a Si3N4 ball. The favorable tribological performance of the Cr3C2–NiCr–Mo–BaF2 composite at high temperatures results from the synergistic lubrication of MoOx, BaF2 and BaMoO4.
Originality/value
This paper reports a new Cr3C2–NiCr matrix self-lubricating composite with better tribological properties than Cr3C2–NiCr composite at temperatures up to 900°C through Mo and BaF2 addition.
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Jianrong Hou and Xiaofeng Zhao
The purpose of the paper is to develop a methodological framework for supply chain risk management using the hierarchical holographic modeling approach. It analyses supply chain…
Abstract
Purpose
The purpose of the paper is to develop a methodological framework for supply chain risk management using the hierarchical holographic modeling approach. It analyses supply chain risks in a systematic manner and develops a hierarchical methodology for identifying, prioritizing and managing the potential supply chain risks.
Design/methodology/approach
This research reviews supply chain risk management literature and develops a conceptual framework, which outlines general principles and guidelines for managing risks in a systematic manner. Through decomposition, the complexity of supply chain risk can be identified by analyzing smaller subsystems.
Findings
The paper provides a conceptual framework to identify supply chain risks from multiple overlapping perspectives. The structured filtering and ranking procedure enables decision-makers to focus on the most critical risks. The research shows that the supply chain risks associated with the sub-systems within the hierarchical structure contribute to and ultimately determine the risks of the overall supply chain system.
Research limitations/implications
The risks associated with each sub system within the hierarchical structure can contribute to and determine the risks of the overall supply chain system. Further applications in various companies and industry sectors would benefit supply chain managers on a case-by-case basis.
Practical implications
The hierarchical risk identification framework can serve as guidance for applications to specific supply chain systems and processes. The framework from a holistic overlapping perspective can efficiently and effectively help supply chain managers identify supply chain risks and facilitate the evaluation of the subsystem risks.
Originality/value
The paper applies system thinking in supply chain management and presents an efficient and practical framework for supply chain risk identification and evaluation.
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Xiaofeng Zhao, Hui Zhao and Jianrong Hou
B2B e‐hubs have been studied by IS researchers for close to a decade, and supply chain integration is a critical topic for supply chain management. However, the interface of the…
Abstract
Purpose
B2B e‐hubs have been studied by IS researchers for close to a decade, and supply chain integration is a critical topic for supply chain management. However, the interface of the two topic areas has not received adequate attention from both researchers and practitioners. This paper aims to examine the impact of B2B e‐hubs on supply chain integration, with particular emphasis on information integration, B2B e‐hub architecture, and enabling technologies.
Design/methodology/approach
General system theory (GST) provides the theoretical framework. The main approach is theoretical analysis of information integration and development of e‐hub architecture. The paper discusses how information integration can be achieved through B2B e‐hubs and explores extensible markup language e‐hub architecture and technologies.
Findings
GST could provide the theoretical framework of integration, whereas information integration is the foundation of broader supply chain integration. E‐hubs open up communication and enlarge networking opportunities and thus tremendously affect information integration. By analyzing B2B e‐hubs, this paper explores the mechanism of information integration and points out managerial and technical limitations. Although there are many challenges, e‐hubs create value by aggregating and matching buyers and sellers, creating marketplace liquidity, and reducing transaction costs. E‐hubs could be a crucial solution to supply chain integration.
Originality/value
The paper uses GST as the theoretical foundation to analyze information integration in supply chain operations. The paper explores how e‐hubs can support supply chain integration, examines the design and development of B2B e‐hub architecture, and compares some enabling technologies. The research provides an understanding of how data interchange solutions can be implemented in supply chain operations.
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Xiaofeng Zhao, Jianrong Hou and Kenneth Gilbert
Waiting lines and delays have become commonplace in service operations. As a result, customer waiting time guarantee is a widely used competition strategy in service industries…
Abstract
Purpose
Waiting lines and delays have become commonplace in service operations. As a result, customer waiting time guarantee is a widely used competition strategy in service industries. To implement waiting time guarantee strategy, managers need to not only know the average of waiting time, but also the variance around average waiting time. This paper aims to discuss these issues.
Design/methodology/approach
This research provides a mathematically exact expression for the coefficient of variation of waiting time for Markov queues. It then applies the concept of isomorphism to approximate the variance of customer waiting time in a general queue. Simulation experiments are conducted to verify the accurate approximations.
Findings
A significant feature of the approximation method is that it is mathematically tractable and can be implemented in a spreadsheet format. It provides a practical way to estimate the variance of customer waiting time in practice. The results demonstrate the usefulness of the queuing models in providing guidance on implementing appointment scheduling and waiting time guarantee strategy. Also, the spreadsheet can be used to conduct what-if analysis by inputting different parameters.
Originality/value
This paper develops a simple, easy-to-use spreadsheet model to estimate the standard deviation of waiting time. The approximation requires only the mean and standard deviation or the coefficient of variation of the inter-arrival and service time distributions, and the number of servers. A spreadsheet model is specifically designed to analyze the variance of waiting time.
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Keju Yan, Zhichuan Guan, Hao Chen, Xiaofeng Zhao and Hongning Zhang
Casing damage problems are increasingly prominent in oil fields, most of which were caused by casing external squeezing loads. The traditional calculation method of casing…
Abstract
Purpose
Casing damage problems are increasingly prominent in oil fields, most of which were caused by casing external squeezing loads. The traditional calculation method of casing external squeezing loads is not very accurate now, especially in complex formation. The purpose of this paper is to propose a new calculation method to solve the problem of actual casing loads under above conditions.
Design/methodology/approach
Based on Lame’s model of elastic mechanics, a new calculation method of casing external squeezing loads is deduced. Comprehensive influence laws of the loads which caused by in-situ stress, internal pressure, formation parameters, cement annulus parameters and casing parameters are analyzed.
Findings
The paper provides a new calculation method of casing external squeezing loads, by which the dispersion effect of internal liquid pressure caused by casing wall material is eliminated. The main influence factors of casing external squeezing loads are in-situ stress and formation elastic modulus.
Research limitations/implications
The model and boundary conditions used in the paper is based on elastic mechanics. The accuracy of the calculation results depends on the quality and accuracy of the input formation parameters.
Originality/value
This paper proposes a new method to calculate casing external squeezing loads. And compared with traditional methods, this method is more practical.
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Bo Tang, Xiaofeng Yang, Jiangong Zhang, Zhibin Zhao, Hao Chen and Gang Liu
This paper aims to propose a method for accurate radar echo simulation of wind turbines (WTs) array. It can solve the problem of passive interference from wind farms to…
Abstract
Purpose
This paper aims to propose a method for accurate radar echo simulation of wind turbines (WTs) array. It can solve the problem of passive interference from wind farms to neighboring radar stations.
Design/methodology/approach
First of all, the equivalent model of scattering centers of a single WT is obtained by using the spatial spectrum estimation method, and the accuracy of this model is verified by the scaled model experiment; then scattering centers model of WTs array was established by using the spatial coordinate transformation method. According to the position relationship between the model and the radar, and combined with the multipath scattering theory, the radar echo equation of WTs array was deduced. Finally, the simulation analysis is carried out with the four GoldWind 77/1500 WTs as an example and compared with the traditional methods.
Findings
This paper verifies the accuracy of the equivalent model of scattering centers through the WT scaled model experiment, and through simulation analysis, it is found that the result of this method is more consistent with the multipath scattering of radar echo between WTs array in practical engineering than the traditional method.
Originality/value
Based on the theory of high-frequency scattering, this paper introduces scattering centers into the solution of radar echo and considers the multipath scattering of radar echo, then a method for solving the radar echo of WTs array based on scattering centers is proposed.
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Huizhong Zhang, Yu Zuo, Pengfei Ju, Jian Zhang, Xuhui Zhao, Yuming Tang and Xiaofeng Zhang
The purpose of this paper is to study the variations of composition and properties of the passive film on 316 L stainless steel surface in 80°C, 0.5 mol L-1 H2SO4 + 2 mg L-1 NaF…
Abstract
Purpose
The purpose of this paper is to study the variations of composition and properties of the passive film on 316 L stainless steel surface in 80°C, 0.5 mol L-1 H2SO4 + 2 mg L-1 NaF solution, is helpful to understand the mechanisms of corrosion resistancethe of plated Pd on 316 L ss.
Design/methodology/approach
The variations of composition and properties of the passive film on 316 L stainless steel surface in 80°C, 0.5 mol L-1 H2SO4 + 2 mg L-1 NaF solution after connected to Pd electrode were studied with methods of potential monitor, X-ray photoelectron spectroscopy analysis and electrochemical impedance spectrum (EIS) measurement.
Findings
By connecting to a Pd electrode, the potential of the SS sample increased from the active region to the passive region. By connecting to the Pd electrode, the contents of Cr, Cr(OH)3 and Fe3O4 in passive film increased obviously. With increased Pd/SS area ratio, the Cr(OH)3 content in passive film increased but the Fe3O4 content changed little. The results show that after connecting to Pd the corrosion resistance of the passive film on 316 L stainless steel increases obviously, which may be attributed to the more compact passive film because of higher Cr, Cr(OH)3 and Fe3O4 contents and less point defects in the film.
Originality/value
The effects and mechanism of Pd on passivation of SS was studied.
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Thandiwe Bongani Radebe, Zhongjie Huan and Jeffrey Baloyi
South Africa is the highest consumer of commercial energy per capita in Africa, ranking 16th in the world for primary energy consumption. It is also ranked among the bottom 50 of…
Abstract
Purpose
South Africa is the highest consumer of commercial energy per capita in Africa, ranking 16th in the world for primary energy consumption. It is also ranked among the bottom 50 of the 150 countries regarding energy efficiency. The cold chain is a large contributor through refrigerated transport vehicles. To comply with the changing climate regulations, cryogenic and eutectic systems are systems with great potential for small distance refrigerated transport. The purpose of this paper is to introduce eutectic system to medium distance refrigerated transport.
Design/methodology/approach
This study presents the potential use of Eutectic plates inside a medium refrigerated transport vehicle, by numerically investigating the characteristics of phase change material eutectic plates applied at low-temperature ranges. A physical model and a mathematical model for three-dimensional transient natural flow were developed as proposed by Xiaofeng and Zhang. Using the governing equation of mass, momentum and energy conservation, three Eutectic plate configurations were modeled and simulated in ANSYS Fluent for 5 h.
Findings
A uniform heat transfer and airflow condition inside a refrigerated compartment were predicted using the Reynolds stress model. The configuration with eutectic plates placed at the top and side showed great potential for the system functioning in the South African climate.
Research limitations/implications
Medium refrigerated transport vehicle.
Originality/value
This configuration had a high-temperature distribution across the compartment and promoted high air circulations, showing that it could be ideal for medium refrigerated transport vehicles delivering perishable foodstuffs or non-food goods.
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Qiang Zhang, Xiaofeng Li, Yundong Ma and Wenquan Li
In this paper, the C80 special coal gondola car was taken as the subject, and the load test data of the car body at the center plate, side bearing and coupler measured on the…
Abstract
Purpose
In this paper, the C80 special coal gondola car was taken as the subject, and the load test data of the car body at the center plate, side bearing and coupler measured on the dedicated line were broken down to generate the random load component spectrums of the car body under five working conditions, namely expansion, bouncing, rolling, torsion and pitching according to the typical motion attitude of the car body.
Design/methodology/approach
On the basis of processing the measured load data, the random load component spectrums were equivalently converted into sinusoidal load component spectrums for bench test based on the principle of pseudo-damage equivalence of load. Relying on the fatigue and vibration test bench of the whole railway wagon, by taking each sinusoidal load component spectrum as the simulation target, the time waveform replication (TWR) iteration technology was adopted to create the drive signal of each loading actuator required for the fatigue test of car body on the bench, and the drive signal was corrected based on the equivalence principle of measured stress fatigue damage to obtain the fatigue test loads of car body under various typical working conditions.
Findings
The fatigue test results on the test bench were substantially close to the measured test results on the line. According to the results, the relative error between the fatigue damage of the car body on the test bench and the measured damage on the line was within the range of −16.03%–27.14%.
Originality/value
The bench test results basically reproduced the fatigue damage of the key parts of the car body on the line.
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Dun Ao, Qian Cao and Xiaofeng Wang
This paper addresses the limitations of current graph neural network-based recommendation systems, which often neglect the integration of side information and the modeling of…
Abstract
Purpose
This paper addresses the limitations of current graph neural network-based recommendation systems, which often neglect the integration of side information and the modeling of complex high-order interactions among nodes. The research motivation stems from the need to enhance recommendation performance by effectively utilizing all available data. We propose a novel method called MSHCN, which leverages hypergraph neural networks to integrate side information and model complex interactions, thereby improving user and item representations.
Design/methodology/approach
The MSHCN method employs a hypergraph structure to incorporate various types of side information, including social relationships among users and item attributes, which are essential for enriching user and item representations. The k-means clustering algorithm is utilized to create item-associated hypergraphs, while sentiment analysis on user reviews refines the modeling of user interests. Additionally, hypergraphs are constructed for user-user and item-item interactions based on interaction similarity. MSHCN also incorporates contrastive learning as an auxiliary task to enhance the representation learning process.
Findings
Extensive experiments demonstrate that MSHCN significantly outperforms existing recommendation models, particularly in its ability to capture and utilize side information and high-order interactions. This results in superior user and item representations and improved recommendation performance.
Originality/value
The novelty of MSHCN lies in its use of a hypergraph structure to integrate diverse side information and model intricate high-order interactions. The incorporation of contrastive learning as an auxiliary task sets it apart from other hypergraph-based models, providing a significant enhancement in recommendation accuracy.