Abstract
Purpose
The purpose of this paper is to investigate the effects of coupling agents on the structure and properties of the nanocomposite films and clarify their mechanism. Polyimide (PI)/Al2O3 nanocomposite films were prepared using different coupling agents.
Design/methodology/approach
Poly(amic acid) (PAA) was firstly synthesised from appropriate pyromellitic diannanocomposite and oxydianiline in N‐dimethylacetamide. Calculated amount of nano‐Al2O3 particles modified by different coupling agents (KH550, KH560, KH570 and AE3012) were added to PAA solution by an ultrasonic‐mechanical method and PI/nano‐Al2O3 film was fabricated by heat curing. The microstructure, thermal stability, mechanical properties and electric breakdown strength of the films were characterised.
Findings
The addition of coupling agents could greatly improve the dispersion homogeneity of Al2O3 nano‐particles in PI matrix. Results of corresponding characterisations indicated that both the thermal stability and mechanical properties of PI/Al2O3 nanocomposite film with KH550 were greater/better than others, while AE3012 could improve the electric breakdown strength.
Research limitations/implications
In the present discussion, the effects of different coupling agents, KH550, KH560, KH570 and AE3012, were investigated. Results of this research work would be beneficial to an in‐depth understanding on the relationship between microstructure and properties of PI composites, and further promote the development of the high‐performance PI insulating materials.
Originality/value
The four coupling agents, KH550, KH560, KH570 and AE3012, were firstly used to disperse the nano‐Al2O3 particles in PI matrix. The effects of coupling agents on microstructure and properties of composites were discussed by the authors in detail.
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Yong-Hua Li, Ziqiang Sheng, Pengpeng Zhi and Dongming Li
How to get a lighter and stronger anti-rolling torsion bar has become a barrier for the development of high-speed railway vehicles. The purpose of this paper is to realize the…
Abstract
Purpose
How to get a lighter and stronger anti-rolling torsion bar has become a barrier for the development of high-speed railway vehicles. The purpose of this paper is to realize the multi-objective optimization of an anti-rolling torsion bar with a Modified Non-dominated Sorting Genetic Algorithm III (MNSGA-III), which aims to obtain a better design scheme of an anti-rolling torsion bar device.
Design/methodology/approach
First, the Non-dominated Sorting Genetic Algorithm III (NSGA-III) uses a simulated binary crossover (SBX) operator and a polynomial mutation operator, while the MNSGA-III algorithm proposed in this paper introduces an arithmetic crossover and an adaptive mutation operator to change the crossover and mutate operator in NSGA-III. Second, two algorithms are tested by ZDT3, ZDT4 functions. Both algorithms set the same population size and evolutionary generation, and then compare the results of NSGA-III and MNSGA-III. Finally, MNSGA-III is applied to the multi-objective model of an anti-rolling torsion bar which is established by taking the mass and stiffness of the torsion bar as the optimization object. After that, it obtains the Pareto solution set by solving the multi-objective model with MNSGA-III. The only optimal solution selected from the Pareto solution set is compared with the traditional design scheme of an anti-rolling torsion bar.
Findings
The MNSGA-III converges faster than NSGA-III. Besides, MNSGA-III has better diversity of Pareto solutions than NSGA-III and is closer to the ideal Pareto frontier. Comparing with the results before the optimization, it shows that the volume of the anti-rolling torsion bar reduces by 1.6 percent and the stiffness increases by 3.3 percent. The optimized data verifies the effectiveness of this method proposed in this paper.
Originality/value
The simulated binary crossover operator and polynomial mutation operator of NSGA-III are changed into an arithmetic crossover operator and an adaptive mutation operator, respectively, which improves the optimization performance of the algorithm.
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Yihong Dong and Yingwu Li
Drawing on social information processing theory, this study investigates how platform leadership influences employees’ innovative behavior. Specifically, we propose a theoretical…
Abstract
Purpose
Drawing on social information processing theory, this study investigates how platform leadership influences employees’ innovative behavior. Specifically, we propose a theoretical model that incorporates creative self-efficacy as a mediator and organizational identification as a moderator.
Design/methodology/approach
Multisource data were collected in three waves from 304 employees and their 65 leaders in China.
Findings
Hierarchical linear modeling (HLM) results reveal: (1) a positive association between platform leadership and subordinates’ innovative behavior; (2) creative self-efficacy as a mediator in the relationship between platform leadership and subordinates’ innovative behavior and (3) organizational identification as a moderator in the indirect relationship between platform leadership and subordinates’ innovative behavior through creative self-efficacy, with the indirect effect being stronger when organizational identification is high than when it is low.
Originality/value
From a cross-level perspective, our findings revealed the underlying mechanisms and boundary conditions under which platform leadership influences followers’ innovative behavior.
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Grzegorz Lesiuk, Monika Maria Duda, José Correia, Abilio M.P. de Jesus and Rui Calçada
For nowadays construction purposes, it is necessary to define the life cycle of elements with defects. As steels 42CrMo4 and 41Cr4 are typical materials used for elements working…
Abstract
Purpose
For nowadays construction purposes, it is necessary to define the life cycle of elements with defects. As steels 42CrMo4 and 41Cr4 are typical materials used for elements working under fatigue loading conditions, it is worth to know how they will behave after different heat treatment. Additionally, typical mechanical properties of material (hardness, tensile strength, etc.) are not defining material’s fatigue resistance. Therefore, it is worth to compare, except mechanical properties, microstructure of the samples after heat treatment as well. The paper aims to discuss these issues.
Design/methodology/approach
Samples of normalized 42CrMo4 (and 41Cr4) steel were heat treated under three different conditions. All heat treatments were designed in order to change microstructural properties of the material. Fatigue tests were carried out according to ASTM E647-15 standard using compact tension specimens. Later on, based on obtained results, coefficients C and m of Paris’ Law for all specimens were estimated. Similar procedure was performed for 41Cr4 steel after quenching and tempering in different temperatures.
Findings
The influence of heat treatment on the fatigue crack growth rates (42CrMo4, 41Cr4 steel) has been confirmed. The higher fatigue crack growth rates were observed for lower tempering temperatures.
Originality/value
This study is associated with influence of microstructural properties of the material on its’ fatigue fracture. The kinetic fatigue fracture diagrams have been constructed. For each type of material (and its heat treatment), the Paris law constants were determined.
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Sami Elferik, Mohammed Hassan and Mustafa AL-Naser
The purpose of this paper is to improve the performance of control loop suffering from control valve stiction. Control valve stiction is considered as of one of the main causes of…
Abstract
Purpose
The purpose of this paper is to improve the performance of control loop suffering from control valve stiction. Control valve stiction is considered as of one of the main causes of oscillation in process variables, which require performing costly unplanned maintenance and process shutdown. An adaptive solution to handle valve stiction while maintaining safety and quality until next planned maintenance is highly desirable to save considerable cost and effort.
Design/methodology/approach
This paper implements a new stiction compensation method built using adaptive inverse model techniques and intelligent control theories. Finite impulse response (FIR) model, which is known to be robust, as a compensator for stiction. The parameters of FIR model are tuned in an adaptive way using differential evolution (DE) technique. The performance of proposed method is compared with other two compensation techniques.
Findings
The new method showed excellent performance of the DE–FIR compensator compared to other dynamic inversion methods in terms of minimizing process variability, energy saving and valve stem aggressiveness.
Research limitations/implications
The compensation ability for all compensators reduces with the increase of stiction severity, thus the over shoot case always shows the worst result. In future works, other optimization techniques will be explored to find the appropriate technique that can extend the FIR model size with smallest computation time that can improve the performance of the compensator in over shoot case. In addition, the estimation of the valve residual life based on the level of stiction and effort required by the controller should be considered.
Originality/value
The presented approach represents an original contribution to the literature. It performs stiction compensation without a need for a prior knowledge on the process or the valve models and guarantees a smooth control of the stem movement with a low control effort. The proposed approach differs from previous adaptive methods as it uses stable FIR models and DE to find the appropriate parameters of the inverse model and handle nonlinear behavior of stiction.
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Tamanna Dalwai, Gopalakrishnan Chinnasamy and Syeeda Shafiya Mohammadi
The readability of annual reports is an important feature that determines the quality of communication between a firm and its stakeholders. Extant literature has demonstrated that…
Abstract
Purpose
The readability of annual reports is an important feature that determines the quality of communication between a firm and its stakeholders. Extant literature has demonstrated that readability characteristics of annual reports are crucial in facilitating the investor's ability to process and analyze information, resulting in higher firm performance and lower agency costs. This study examines the relationship between annual report readability, agency costs and the firm performance of listed financial sector companies in Oman.
Design/methodology/approach
Using a sample of 150 firm-year observations of listed financial sector companies on the Muscat Securities Market (MSM) over the period 2014 to 2018, a panel regression analysis is used, along with the system generalized method of moments (GMM) estimation to address endogeneity concerns. The readability of annual reports is proxied by the length of the annual report, the Flesch reading ease and the Flesch–Kincaid index.
Findings
The ordinary least squares (OLS) results suggest that readability proxied by the length of the annual report has no significant relationship with agency cost, return on assets (ROA) or stock returns. The OLS results are confirmed through the system GMM estimation model for agency costs, Tobin's Q and stock returns. Easier-to-read annual reports measured by the Flesch reading ease demonstrate high asset utilization ratio and Tobin's Q. These results emphasize Flesch reading ease measure in explaining the economic significance of agency cost and Tobin's Q. In contrast, difficult-to-read annual reports are observed for firms with high ROA.
Research limitations/implications
The study is limited to the financial sector. Its generalizability could be extended to a similar sector or countries with features similar to Oman. Future studies on readability could be extended to other sectors of Oman, and financial firms with easier-to-read annual reports show a high Tobin's Q, which reflects the confidence of investors in the stock market. These findings may encourage policymakers to regulate the readability features of annual reports and influence the reporting quality of financials and disclosures also including cross-country comparisons.
Practical implications
Financial firms with easier-to-read annual reports show a high Tobin's Q, which reflects the confidence of investors in the stock market. These findings may encourage policymakers to regulate the readability features of annual reports and influence the reporting quality of financials and disclosures.
Originality/value
While the study extends prior literature on readability, agency costs and firm performance, it is also one of the first to examine the financial sector of an emerging country, namely, Oman. The study supports the obfuscation hypothesis through the association of readability measure with agency cost. Unlike prior research that has focused on common computational linguistic literature, this study uses three proxies for readability to assess information quality.
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A lack of visibility into the manufacturer’s production cost information impedes a retailer’s ability to maximize her own profits, especially when market demand is uncertain. The…
Abstract
Purpose
A lack of visibility into the manufacturer’s production cost information impedes a retailer’s ability to maximize her own profits, especially when market demand is uncertain. The purpose of this paper is to investigate the use of an option contract within a one-period two-echelon supply chain in the presence of asymmetric cost information.
Design/methodology/approach
Based on the principal-agent model, the retailer, acting as a Stackelberg leader, offers a menu of option contracts to mitigate the risk of uncertain demand and reveal asymmetric production cost information. The optimal contract in asymmetric and symmetric information scenarios is derived. Finally, the impact of production costs on the optimal contracts and the actors’ profits is explored by numerical experiments.
Findings
By comparing the optimal equilibrium solutions in two scenarios, the authors show that asymmetric cost information has a large impact on the optimal option contract and profits. In addition, information rent is affected by the type differential. The results prove that the level of information asymmetry plays a vital role in option contracts and profits.
Originality/value
Different from the existing literature on private demand information, this paper considers a supply chain with asymmetric cost information in the context of option contracts. Interestingly, not only the production cost but also the probability of a low production cost can affect the option strike price. In addition, from the perspective of the manufacturer, a high cost does not always bring a high information rent. These findings can provide some guidance to decision-makers.
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Xue-Qin Li, Lu-Kai Song and Guang-Chen Bai
To provide valuable information for scholars to grasp the current situations, hotspots and future development trends of reliability analysis area.
Abstract
Purpose
To provide valuable information for scholars to grasp the current situations, hotspots and future development trends of reliability analysis area.
Design/methodology/approach
In this paper, recent researches on efficient reliability analysis and applications in complex engineering structures like aeroengine rotor systems are reviewd.
Findings
The recent reliability analysis advances of engineering application in aeroengine rotor system are highlighted, it is worth pointing out that the surrogate model methods hold great efficiency and accuracy advantages in the complex reliability analysis of aeroengine rotor system, since its strong computing power can effectively reduce the analysis time consumption and accelerate the development procedures of aeroengine. Moreover, considering the multi-objective, multi-disciplinary, high-dimensionality and time-varying problems are the common problems in various complex engineering fields, the surrogate model methods and its developed methods also have broad application prospects in the future.
Originality/value
For the strong demand for efficient reliability design technique, this review paper may help to highlights the benefits of reliability analysis methods not only in academia but also in practical engineering application like aeroengine rotor system.
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Francesco Antonio Perotti, Zoltan Rozsa, Michal Kuděj and Alberto Ferraris
Drawing on the microfoundations theory and rational choice sociology, this study aims to investigate knowledge-sharing microfoundations through knowledge sabotage behaviours in…
Abstract
Purpose
Drawing on the microfoundations theory and rational choice sociology, this study aims to investigate knowledge-sharing microfoundations through knowledge sabotage behaviours in the workplace. As such, it aims to shed light on the adverse impact of knowledge sabotage on a knowledge-sharing climate.
Design/methodology/approach
As a quantitative deductive study, it is based on information collected from 329 employees of European companies by self-administered online surveys. Data validity and reliability has been assessed through a confirmatory factor analysis, and data analysis was carried out by using a covariance-based structural equation modelling technique.
Findings
The findings from the empirical investigation supported the baseline hypotheses of the multilevel conceptual model, which is the positive relationship between organizational trust and environmental knowledge sharing. Then, recurring to a microfoundational exploration, this study supports the mediating indirect effect of job satisfaction and knowledge sabotage in affecting knowledge sharing as a social outcome.
Research limitations/implications
This study concurs to broaden knowledge-sharing awareness among scholars and practitioners, by focusing on knowledge sabotage as its most pernicious counterproductive behaviour. Furthermore, this research provides valuable guidance for the future development of research based on multilevel investigations.
Originality/value
This study builds on the need to explore the numerous factors that affect knowledge sharing in economic organizations, specifically focusing on knowledge sabotage. Adapting Coleman’s bathtub, the authors advance the first multilevel conceptual model used to unveil the knowledge-sharing microfoundations from the perspective of a counterproductive knowledge behaviour.
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Asymmetric cost information exists between a supplier and a manufacturer regarding the manufacturer's process innovation for remanufacturing (PIR), which may hurt the supplier's…
Abstract
Purpose
Asymmetric cost information exists between a supplier and a manufacturer regarding the manufacturer's process innovation for remanufacturing (PIR), which may hurt the supplier's profit. The authors therefore seek to develop a menu of nonlinear pricing contracts for channel information sharing.
Design/methodology/approach
Based on principal–agent theory, the supplier, acting as a Stackelberg leader, designs a menu of nonlinear pricing contracts to impel the manufacturer to disclose its private cost information on PIR (i.e. PIR efficiency). In addition, the authors compare the equilibrium outcomes under asymmetric and symmetric information to examine the effects of asymmetric PIR information on the production policies and profits of the supplier and the manufacturer.
Findings
The proposed contract menu encourages th4e manufacturer to spontaneously share PIR efficiency information with the supplier. Asymmetric PIR information may distort the output of new products upward or downward, but the output of remanufactured products may only be distorted downward. In addition, the manufacturer with high PIR efficiency gains information rent, and interestingly, the increase in the probability of low PIR efficiency amplifies its information rent. Finally, an asymmetric information environment may increase the threshold for the manufacturer to enter remanufacturing.
Originality/value
The authors probe the issue of the supplier's contract design by jointly considering remanufacturing, process innovation and information asymmetry. The paper expands the influencing mechanism of process innovation information in the remanufacturing field. The authors also observe new results that may offer guidance to decision makers.