Weijia Lu, Chengxi Zhang, Fei Liu, Jin Wu, Jihe Wang and Lining Tan
This paper aims to investigate the relative translational control for multiple spacecraft formation flying. This paper proposes an engineering-friendly, structurally simple, fast…
Abstract
Purpose
This paper aims to investigate the relative translational control for multiple spacecraft formation flying. This paper proposes an engineering-friendly, structurally simple, fast and model-free control algorithm.
Design/methodology/approach
This paper proposes a tanh-type self-learning control (SLC) approach with variable learning intensity (VLI) to guarantee global convergence of the tracking error. This control algorithm utilizes the controller's previous control information in addition to the current system state information and avoids complicating the control structure.
Findings
The proposed approach is model-free and can obtain the control law without accurate modeling of the spacecraft formation dynamics. The tanh function can tune the magnitude of the learning intensity to reduce the control saturation behavior when the tracking error is large.
Practical implications
This algorithm is model-free, robust to perturbations such as disturbances and system uncertainties, and has a simple structure that is very conducive to engineering applications.
Originality/value
This paper verified the control performance of the proposed algorithm for spacecraft formation in the presence of disturbances by simulation and achieved high steady-state accuracy and response speed over comparisons.
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Ming Zhao, Zhengdong Huang and Liping Chen
The purpose of this paper is to introduce a new method to carry out the design optimization of the tool head system in the heavy‐duty machine tool where closed hydrostatic…
Abstract
Purpose
The purpose of this paper is to introduce a new method to carry out the design optimization of the tool head system in the heavy‐duty machine tool where closed hydrostatic guideways with multiple pockets are employed.
Design/methodology/approach
A more accurate method of pressure calculation for closed hydrostatic guideways is introduced. Then, a multidisciplinary design optimization (MDO) model is formulated for design of a tool head system, which minimizes the highest pocket pressure under some constraints from machining accuracy and vibration resistance requirements as well as constraints from ballscrew design specifications. Finally, a metamodel‐based design space alternation (DSA) strategy is proposed to solve the optimization problem.
Findings
The results show that the maximum pocket pressure in a tool head system can be reduced over 47 percent with a proper design while all the constraints are satisfied. As a consequence, the tool head system can safely work under the maximum output pressure of oil supply system.
Originality/value
This paper introduces a more accurate method of pressure calculation for multi‐pocket closed hydrostatic guideways, develops a metamodel‐based MDO model for the tool head system, and proposes a DSA strategy to solve the MDO problem.
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To discuss some of the work of Heinz von Foerster with regard to multidimensional visualization.
Abstract
Purpose
To discuss some of the work of Heinz von Foerster with regard to multidimensional visualization.
Design/methodology/approach
An introduction to multidimensional visualization, followed with the connections derived from the Biological Computer Laboratory.
Findings
Visualization provides insight through images. Considers the steps involved in interacting and learning so that this will lead the individual into their own “concept formation”.
Originality/value
Studies aspects of Heinz von Foerster's work that are of importance for understanding multidimensional visualization.
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T.V. Grissom, M. McCord, D. McIlhatton and M. Haran
The purpose of this paper, which is the first of a two-part series, is to build upon the established research on environmental economics and sustainability theory developed by…
Abstract
Purpose
The purpose of this paper, which is the first of a two-part series, is to build upon the established research on environmental economics and sustainability theory developed by Ramsey (1928), Weitzman (2007) and Gollier (2010). The Ramsey-Weitzman-Gollier model, with the contribution of Howarth (2009) and Nordhaus (2007a, b), focuses on discount rate development for environmental and long-term assets, linking discounted utility analysis embedded in the CCAPM model of Lucas (1978) to the policy concerns associated with the valuation of public and sustainable resources. This paper further investigates these issues to the rates structure appropriate for exhaustible resources with a particular emphasis on urban land, based upon the differentiation of strong and weak form sustainability concepts constrained by the objectives of the sustainable criterion of Daly and Cobb (1994).
Design/methodology/approach
The paper integrates the concepts of discount rate development for environmental and long-term assets and discounted utility analysis to the policy concerns associated with the valuation of public and sustainable resources. It develops new theoretical insight in order to allow the theoretical formulation of discount and capitalization rates that can be empirically applied and tested.
Findings
The paper provides theoretical support for a new approach concerned with the development of capitalization and discount rates in the valuation of non-renewable resources. A key concern of valuing non-renewable or limited resource endowments (in space or time) is the problem of irreversible investment or irrevocable decision implementation as suggested by Arrow-Fisher (1974), Krautkraemer (1985) and Daly and Cobb (1994). It investigates the challenge with developing capitalization rates and valuation of depleting resources temporally, within the constraints of sustainability. To achieve this, an optimal control discounting procedure subject to a sustainable objective statement is employed – in this context it suggests that sustainability should be treated as an alternative to traditional growth and the maximization of near-term returns.
Originality/value
This paper extends the construct of developing rates structures appropriate for the valuation of exhaustible resources. It places a conceptual emphasis on urban land development. The measures developed and the insights gained may serve as a basis for future research on the optimal levels of sustainable development appropriate for different nations.
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THE increase in aircraft sizes which is envisaged in the next few years, raises the question of adequate lofting space where the traditional method by fairing by eye is still…
Abstract
THE increase in aircraft sizes which is envisaged in the next few years, raises the question of adequate lofting space where the traditional method by fairing by eye is still used. This problem can be met by the adoption of a mathematical technique which not only eliminates the need for considerable space but also provides close and accurate control of the body form. Whilst the size factor may make the lofting problem more acute and so lead to a better appreciation of a mathematical method, the use of such a method is equally valuable in the case of smaller aircraft in that it enables the loftsman to blend all parts of the body form together and to provide the layout draughtsman with accurate shapes for all parts which contain part of the body contour.
Reviews the various problems associated with tunnels (such asunderground railway and sewerage systems) below urban areas, and theireffects on surface buildings. Discusses briefly…
Abstract
Reviews the various problems associated with tunnels (such as underground railway and sewerage systems) below urban areas, and their effects on surface buildings. Discusses briefly tunnelling techniques and the effect on buildings, although makes the point that no reliable data exists on the techniques and their effect on ground displacement (which causes problems to buildings). Gives brief guidelines to structural condition surveyors in assessing actual and potential damage to buildings from tunnelling.
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Abdurahman Mushabab Al-Ahmari, Osama Abdulhameed and Awais Ahmad Khan
In additive manufacturing processes such as stereolithography and fused deposition modeling, optimal part orientation is pivotal in improving the quality of the part. This paper…
Abstract
Purpose
In additive manufacturing processes such as stereolithography and fused deposition modeling, optimal part orientation is pivotal in improving the quality of the part. This paper aims to propose an automatic and optimal part orientation system to improve part quality/accuracy in additive manufacturing, which minimizes the production time and hence reduces the cost of product.
Design/methodology/approach
The developed system reads STEP AP 203 E2 file from CATIA V5 and generates data extraction output file by extracting the relevant geometrical and topological data using an object-oriented approach. Afterwards, the algorithms and rules are developed to extract and recognize feature faces along with their geometric properties such as face type, face area, parallelism and perpendicularity. The feature data obtained that are used to develop feasible part orientations depend on the maximization of G&DT for all part faces. The automatic slicing is then achieved by creating slicing file using CATVBA editor inside CATIA V5.
Findings
After slicing, output data are exported in Excel data sheet to calculate the total additive volume of the part. The building time of the part is then calculated on the basis of machine parameters, part geometry, part height, layer thickness and amount of support volume needed to build the part. The optimal orientation of the part is achieved by maximization of G&DT value and minimization of production time. The proposed methodology is tested using an illustrative example.
Originality/value
Although lot of approaches have been discussed in the literature, automation of setup planning/orientation of the part in additive manufacturing is not fully attained. Therefore, the article focuses on the automation of setup planning by adding automatic feature extraction and recognition module along with the automatic slicing during setup planning. Moreover, the significance of adding feature extraction and recognition module is to achieve best accuracy for form feature faces and hence reduction in post processing machining/finishing operations.
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Yong Tan, Vincent Charles, Doha Belimam and Shabbir Dastgir
This study investigates the interrelationships between efficiency, competition and risk in the Chinese banking industry.
Abstract
Purpose
This study investigates the interrelationships between efficiency, competition and risk in the Chinese banking industry.
Design/methodology/approach
Parametric stochastic frontier analysis is used to estimate bank efficiency; the Lerner index is used as the competition indicator; accounting ratios and a translog function are used to measure different types of risk and finally, the three-stage least square estimator is used to investigate the interrelationships.
Findings
The results of this study show that the impact of competition on different types of risk is significant and positive, while there is a significant and positive impact of credit risk, liquidity risk and capital risk on bank competition. In addition, the findings demonstrate that the interrelationships between efficiency and competition are significant and negative. The authors do not find any robust interrelationships between different types of risk and different types of efficiency; the authors find that diversification and higher levels of profitability reduce bank credit risk. The results suggest that a higher developed banking sector reduces the level of bank competition in China.
Originality/value
This is the first piece of research that comprehensively investigates the interrelationships between different types of risk, competition and different efficiencies in China.
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Human resource management
Abstract
Subject area
Human resource management
Study level/applicability
This case is suitable for use for advanced-level undergraduate students (e.g. in their third or fourth year of study) and graduate-level students enrolled in human resource management, industrial relations, organizational behavior and legal courses (e.g. business law and ethics, employment law). It can be used also in training courses and sexual harassment workshops for employees, particularly those with supervisory responsibilities or who are involved in personnel, training, or industrial relations activities. The case has been class tested with MBA students enrolled in a course on organizational behavior.
Case overview
In March 2014, William Wong, the CEO of Zejaya Corporation faced a dilemma. He had just been told some disturbing news about Larry Pang, his executive director, which may or may not have legal implications for the company in relation to sexual harassment. Two of his managers had confided in him that Linda Tan, one of his managers who had recently resigned, had asked them to tell him about Pang's repeated attempts to court her in the past several months. He was undecided on how he should handle the problem.
Expected learning outcomes
This case was developed for class discussion rather than to illustrate either effective or ineffective handling of a management situation. The case provides students the opportunity to learn about the potential ethical and legal issues surrounding workplace romance and sexual harassment at work.
Supplementary materials
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