Search results

1 – 10 of 429
Article
Publication date: 28 February 2022

Jie Cen, Mian Wang, Yan Yang, Jing Li and Rongjian Yu

In the context of collaborative research and development (R&D), multi-actor participation and multi-resource integration of technological knowledge has become the…

Abstract

Purpose

In the context of collaborative research and development (R&D), multi-actor participation and multi-resource integration of technological knowledge has become the mainstream paradigm for the R&D and spillover of industry generic technology (GT). As GT's core characteristics, “fundamentality” and “externality,” make differential requests on knowledge bases regarding the R&D and spillover of GT (SGT). Knowledge breadth can enhance the generality of technology. The purpose of this paper is to integrate “generic technology R&D” and “generic technology spillover” into a single study, and try to solve the theoretical problem of “whether broader mean more general?”

Design/methodology/approach

This paper collects and collates the patent data from the two patent databases of Derwent and SooPAT, and then makes an empirical analysis of the patent data collected by the authors with the data analysis software Stata.

Findings

Taking 352 strategic emerging firms in China as the sample, this paper examined the effects of general knowledge breadth (GKB) and specific knowledge breadth (SKB) on the R&D and SGT. The authors concluded that both general and SKB have a positive effect on the R&D of GT (RGT), and the latter has a greater effect. There is a significant inverted U-shaped relationship between SKB and SGT.

Originality/value

The theoretical contributions of this paper are as follows. GT can effectively link different technologies and knowledge fields (Gambardella and Giarratana, 2013; Appio et al., 2017a, b). Therefore, existing studies regard the role of knowledge breadth on the R&D and SGT as an existing hypothesis. This paper challenges such hypothesis in two ways. First, this paper divides knowledge breadth into “general knowledge breadth” and “specific knowledge breadth” in response to the insufficient division of knowledge breadth in previous research, although some existing studies have examined the antecedents of the R&D and SGT from the perspective of R&D and SGT. Thus, the authors define GKB as the scope of context-free knowledge and SKB as the scope of context-specific knowledge, both of which shows differential nature, source and application. Second, this paper decomposes the effect of knowledge breadth on RGT, as well as on SGT, basing on distinguishing the SKB from GKB. Existing research reaches a consensus of the positive role of knowledge breadth, no matter on RGT or SGT (e.g. Schmidt et al., 2016; Appio et al., 2017a, b). Yet, such hypothesis ignores the refinement and decomposition of “knowledge breadth” in the research field of R&D and SGT, which is essential in promoting the development of GT theory. In this paper, the authors find that these two types of knowledge breadths play different roles in the RGT, and especially SKB plays a double-edged sword effect on the SGT.

Details

European Journal of Innovation Management, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 1460-1060

Keywords

Book part
Publication date: 16 September 2014

Mian Wang and Yajing Feng

Special education in China has lagged behind regular education for many years, however, the past few decades, the government has made considerable efforts to develop and…

Abstract

Special education in China has lagged behind regular education for many years, however, the past few decades, the government has made considerable efforts to develop and improve the special education system. While the citizens of China have had a generic moral interest in disability since ancient times, the development of special education schools did not occur until American and European missionaries started schools for the visually and hearing impaired in the 19th century. The next major influence in the development of the special education system occurred with China’s Cultural Revolution in 1978. Interestingly, there is not any exclusive legislation on special education but in the 1980s, the government started Learning in Regular Classrooms (LRC), which is China’s version of inclusion. LRC has progressed rapidly the past two decades; however, the quality of instruction is low due to a lack of specialists, a shortage of personnel, inadequate funding, and limited technology as well as other barriers that are delineated in the chapter. The chapter emphasizes the government’s recent efforts in in-service teacher training, the preparation of preservice teachers, working with families, developing community rehabilitation training programs, and implementing evidence-based practices. Special education in China today is at a good place but it has quite a way from the ideal situation.

Details

Special Education International Perspectives: Practices Across the Globe
Type: Book
ISBN: 978-1-78441-096-4

Article
Publication date: 1 July 2020

Mehmet Konar, Aydin Turkmen and Tugrul Oktay

The purpose of this paper is to use an ABC algorithm to improve the thrust–torque ratio of a rotating-wing unmanned aerial vehicle (UAV) model.

Abstract

Purpose

The purpose of this paper is to use an ABC algorithm to improve the thrust–torque ratio of a rotating-wing unmanned aerial vehicle (UAV) model.

Design/methodology/approach

The design of UAVs, such as aircraft, drones, helicopters, has become one of the popular engineering areas with the development of technology. This study aims to improve the value of thrust–torque ratio of an unmanned helicopter. For this purpose, an unmanned helicopter was built at the Faculty of Aeronautics and Astronautics, Erciyes University. The maximum thrust–torque ratio was calculated considering the blade length, blade chord width, blade mass density and blade twist angle. For calculation, artificial bee colony (ABC) algorithm was used. By using ABC algorithm, the maximum thrust–torque ratio was obtained against the optimum input values. For this purpose, a model with four inputs and a single output is formed. In the generated system model, optimum thrust–torque ratio was calculated by changing the input values used in the ±5% range. As a result of this study, approximately 31% improvement was achieved. According to these results, the proposed approach will provide convenience to the designers in the design of the rotating-wing UAV.

Findings

According to these results, approximately 31% improvement was achieved, and the proposed approach will provide convenience to the designers in the design of the rotating-wing UAV.

Research limitations/implications

It takes a long time to obtain the optimum thrust–torque ratio value through the ABC algorithm method.

Practical implications

Using ABC algorithm provides to improve the value of thrust–torque ratio of an unmanned helicopter. With this algorithm, unmanned helicopter flies more than ever. Thus, the presented method based on the ABC algorithm is more efficient.

Social implications

The application of the ABC algorithm method can be used effectively to calculate the thrust–torque ratio in UAV.

Originality/value

Providing an original and penetrating a method that saves time and reduces the cost to improve the value of thrust–torque ratio of an unmanned helicopter.

Details

Aircraft Engineering and Aerospace Technology, vol. 92 no. 8
Type: Research Article
ISSN: 1748-8842

Keywords

Article
Publication date: 6 July 2015

Ismaila Bayo Tijani, Rini Akmeliawati, Ari Legowo and Agus Budiyono

– The purpose of this paper is to develop a multiobjective differential evolution (MODE)-based extended H-infinity controller for autonomous helicopter control.

Abstract

Purpose

The purpose of this paper is to develop a multiobjective differential evolution (MODE)-based extended H-infinity controller for autonomous helicopter control.

Design/methodology/approach

Development of a MATLAB-based MODE suitable for controller synthesis. Formulate the H-infinity control scheme as an extended H-infinity loop shaping design procedure (H -LSDP) with incorporation of v-gap metric for robustness to parametric variation. Then apply the MODE-based algorithm to optimize the weighting function of the control problem formulation for optimal performance.

Findings

The proposed optimized H-infinity control was able to yield set of Pareto-controller candidates with optimal compromise between conflicting stability and time-domain performances required in autonomous helicopter deployment. The result of performance evaluation shows robustness to parameter variation of up to 20 per cent variation in nominal values, and in addition provides satisfactory disturbance rejection to wind disturbance in all the three axes.

Research limitations/implications

The formulated H-infinity controller is limited to hovering and low speed flight envelope. The optimization is focused on weighting function parameters for a given fixed weighting function structure. This thus requires a priori selection of weighting structures.

Practical implications

The proposed MODE-infinity controller algorithm is expected to ease the design and deployment of the robust controller in autonomous helicopter application especially for practicing engineer with little experience in advance control parameters tuning. Also, it is expected to reduce the design cycle involved in autonomous helicopter development. In addition, the synthesized robust controller will provide effective hovering/low speed autonomous helicopter flight control required in many civilian unmanned aerial vehicle (UAV) applications.

Social implications

The research will facilitate the deployment of low-cost, small-scale autonomous helicopter in various civilian applications.

Originality/value

The research addresses the challenges involved in selection of weighting function parameters for H-infinity control synthesis to satisfy conflicting stability and time-domain objectives. The problem of population initialization and objectives function computation in the conventional MODE algorithm are addressed to ensure suitability of the optimization algorithm in the formulated H-infinity controller synthesis.

Details

Aircraft Engineering and Aerospace Technology: An International Journal, vol. 87 no. 4
Type: Research Article
ISSN: 0002-2667

Keywords

Article
Publication date: 18 October 2011

Ismaila B. Tijani, Rini Akmeliawati, Ari Legowo, Agus Budiyono and A.G. Abdul Muthalif

The purpose of this paper is to present the synthesis of a robust controller for autonomous small‐scale helicopter hovering control using extended H loop shaping design…

Abstract

Purpose

The purpose of this paper is to present the synthesis of a robust controller for autonomous small‐scale helicopter hovering control using extended H loop shaping design techniques.

Design/methodology/approach

This work presents the development of a robust controller for smooth hovering operation required for many autonomous helicopter operations using H loop shaping technique incorporating the Vinnicombe‐gap (v‐gap) metric for validation of robustness to uncertainties due to parameter variation in the system model. Simulation study was conducted to evaluate the performance of the designed controller for robust stability to uncertainty, disturbance rejection, and time‐domain response in line with ADS‐33E level 1 requirements.

Findings

The proposed techniques for a robust controller exhibit an effective performance for both nominal plant and 20 percent variation in the nominal parameters in terms of robustness to uncertainty, disturbance wind gust attenuation up to 95 percent, and transient performance in compliance with ADS‐33E level 1 specifications.

Research limitations/implications

The controller is limited to hovering and low‐speed flight envelope.

Practical implications

This is expected to provide efficient hovering/low‐speed autonomous helicopter flight control required in many civilian unmanned aerial vehicles applications. Also, the technique can be used to simplify the number of robust gain‐scheduled linear controllers required for wide‐envelope flight.

Social implications

The research will facilitate the deployment of low cost, small‐scale autonomous helicopters in various civilian applications.

Originality/value

The research addresses the challenges of parametric variation inherent in helicopter hovering/low‐speed control using an extended H loop shaping technique with v‐gap metric.

Details

Aircraft Engineering and Aerospace Technology, vol. 83 no. 6
Type: Research Article
ISSN: 0002-2667

Keywords

Article
Publication date: 28 October 2014

Mian Du, Siyan Chen and Huan Shao

The purpose of this paper is to investigate the relationship between corporate governance mechanism and firm value of the listed companies in China. Does the better…

Abstract

Purpose

The purpose of this paper is to investigate the relationship between corporate governance mechanism and firm value of the listed companies in China. Does the better corporate governance lead to the higher firm value? Or does the higher firm value make it easy to choose a better governance mechanism? Or they affect each other? In other words, this paper tries to answer whether the corporate governance mechanism is only decided by institutional arrangement, or by market choice according to firm value or performance or by the interaction of institutional arrangement and market choice? It tries to answer whether institutional arrangement maximizes the firm value, or an invisible hand pushes them to arrive at its maximum.

Design/methodology/approach

This paper establishes an analytic framework of simultaneous equations based on causality, which includes five endogenous variables: ownership of larger shareholders, managerial ownership, director compensation, debt financing and firm value. It adopts 1,644 data samples from 274 Chinese listed companies in Shanghai and Shenzhen Stock Exchange during 2007- 2012 after the non-tradable shares reform. Ordinary least squares (OLS) estimation of single equation, 2SLS and 3SLS estimation of simultaneous equations are respectively done to show the differences of these three kinds of estimations.

Findings

The empirical results show that differences exist among OLS, 2SLS and 3SLS estimation. Finally, 3SLS estimation should be adopted because the OLS and 2SLS estimation are biased. There are endogenous relationships between corporate governance mechanism and firm value. Through the 3SLS estimation, it is found that first, ownership concentration and firm value affect each other positively. Second, managerial ownership and firm value affect each other positively; third, director compensation and firm value affect each other negatively, while director compensation and firm performance affect each other positively. Finally, debt financing level and firm value are negatively related to each other.

Practical implications

It means that ownership of large shareholders, managerial ownership, director compensation and debt financing in the Chinese listed companies are found to have a root in the interaction between institutional arrangement and market choice. It is also found that adverse selection occurs when creditors loan to the listed companies. Managerial compensation is positively related to accounting profit, but it is negatively related to firm value because managers increase profit due by earning management. This could only increase the accounting profits and obtain huge cash compensation, but not increase firm value and even harm the interests of shareholders.

Originality/value

This paper not only shows the difference between OLS and 2SLS estimation but also compares the estimation of 2SLS and 3SLS in terms of empirical methods. It gives answers to the following questions: whether the relationship is one-way causality or bilateral causality between ownership concentration, managerial ownership, director compensation and firm value; whether governance mechanism affects firm value by institutional arrangement, or market drives both of them to strike a balance by an invisible hand. In other words, does it make them arrive at equilibrium through the competitive selection process when shareholders, directors, managers and creditors attempt to maximize themselves of their interests?

Details

Chinese Management Studies, vol. 8 no. 4
Type: Research Article
ISSN: 1750-614X

Keywords

Content available
Book part
Publication date: 16 September 2014

Abstract

Details

Special Education International Perspectives: Practices Across the Globe
Type: Book
ISBN: 978-1-78441-096-4

Article
Publication date: 3 January 2017

Rooh ul Amin and Aijun Li

The purpose of this paper is to present μ-synthesis-based robust attitude trajectory tracking control of three degree-of-freedom four rotor hover vehicle.

Abstract

Purpose

The purpose of this paper is to present μ-synthesis-based robust attitude trajectory tracking control of three degree-of-freedom four rotor hover vehicle.

Design/methodology/approach

Comprehensive modelling of hover vehicle is presented, followed by development of uncertainty model. A μ-synthesis-based controller is designed using the DK iteration method that not only handles structured and unstructured uncertainties effectively but also guarantees robust performance. The performance of the proposed controller is evaluated through simulations, and the controller is also implemented on experimental platform. Simulation and experimental results validate that μ-synthesis-based robust controller is found effective in: solving robust attitude trajectory tracking problem of multirotor vehicle systems, handling parameter variations and dealing with external disturbances.

Findings

Performance analysis of the proposed controller guarantees robust stability and also ensures robust trajectory tracking performance for nominal system and for 15-20 per cent variations in the system parameters. In addition, the results also ensure robust handling of wind gusts disturbances.

Originality/value

This research addresses the robust performance of hover vehicle’s attitude control subjected to uncertainties and external disturbances using μ-synthesis-based controller. This is the only method so far that guarantees robust stability and performance simultaneously.

Details

Aircraft Engineering and Aerospace Technology, vol. 89 no. 1
Type: Research Article
ISSN: 1748-8842

Keywords

Article
Publication date: 4 January 2016

Dan Xu, James Ferris Whidborne and Alastair Cooke

The growing use of small unmanned rotorcraft in civilian applications means that safe operation is increasingly important. The purpose of this paper is to investigate the…

1550

Abstract

Purpose

The growing use of small unmanned rotorcraft in civilian applications means that safe operation is increasingly important. The purpose of this paper is to investigate the fault tolerant properties to faults in the actuators of an C 1 adaptive controller for a quadrotor vehicle.

Design/methodology/approach

C 1 adaptive control provides fast adaptation along with decoupling between adaptation and robustness. This makes the approach a suitable candidate for fault tolerant control of quadrotor and other multirotor vehicles. In the paper, the design of an C 1 adaptive controller is presented. The controller is compared to a fixed-gain LQR controller.

Findings

The C 1 adaptive controller is shown to have improved performance when subject to actuator faults, and a higher range of actuator fault tolerance.

Research limitations/implications

The control scheme is tested in simulation of a simple model that ignores aerodynamic and gyroscopic effects. Hence for further work, testing with a more complete model is recommended followed by implementation on an actual platform and flight test. The effect of sensor noise should also be considered along with investigation into the influence of wind disturbances and tolerance to sensor failures. Furthermore, quadrotors cannot tolerate total failure of a rotor without loss of control of one of the degrees of freedom, this aspect requires further investigation.

Practical implications

Applying the C 1 adaptive controller to a hexrotor or octorotor would increase the reliability of such vehicles without recourse to methods that require fault detection schemes and control reallocation as well as providing tolerance to a total loss of a rotor.

Social implications

In order for quadrotors and other similar unmanned air vehicles to undertake many proposed roles, a high level of safety is required. Hence the controllers should be fault tolerant.

Originality/value

Fault tolerance to partial actuator/effector faults is demonstrated using an C 1 adaptive controller.

Details

International Journal of Intelligent Unmanned Systems, vol. 4 no. 1
Type: Research Article
ISSN: 2049-6427

Keywords

Article
Publication date: 5 May 2022

Abuelhassan Elshazly Abuelhassan and Ali AlGassim

Based on social exchange theory (SET) and conservation of resources (COR) theory, this study aims to examine the unique combined impact of procedural justice (PJ) and…

Abstract

Purpose

Based on social exchange theory (SET) and conservation of resources (COR) theory, this study aims to examine the unique combined impact of procedural justice (PJ) and distributive justice (DJ) on proactive customer service performance (PCSP) and general self-efficacy (GSE) in the hospitality industry. It also estimates these variables’ joint effect on PCSP controlling GSE.

Design/methodology/approach

The study’s results were derived from a sample of 380 frontline supervisor–subordinate dyads, placed in 18 five-star hotels, through three-wave data collection. The hypotheses and construct validity were generated through structural equation modeling.

Findings

The combined impact of DJ and PJ on GSE and PCSP was significantly positive, and GSE mediated the relationships between DJ and PCSP as well as PJ and PCSP.

Practical implications

To improve service employees’ GSE and PCSP, hospitality management should guide and encourage managers to highlight and maintain organizational justice (OJ) in all their strategies and operations. DJ and PJ are advised to appreciate service employees’ GSE and extra-role behaviors (e.g. PCSP) through providing organizational resources.

Originality/value

This paper offers unique practical and theoretical contributions to the hospitality industry and associated literature by implementing SET and COR theory with OJ, GSE and PCSP constructs.

Details

International Journal of Contemporary Hospitality Management, vol. 34 no. 7
Type: Research Article
ISSN: 0959-6119

Keywords

1 – 10 of 429