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Article
Publication date: 16 May 2008

S.H. Jalali‐Naini and S.H. Pourtakdoust

The purpose of this paper is to develop a novel solution for the predicted error and introduces a systematic method to develop optimal and explicit guidance strategies for…

436

Abstract

Purpose

The purpose of this paper is to develop a novel solution for the predicted error and introduces a systematic method to develop optimal and explicit guidance strategies for different missions.

Design/methodology/approach

The predicted error is derived from its basic definition through analytical dynamics. The relations are developed for two classes of systems. First, for systems in which the acceleration commands are truncated at a specified time. Second, for systems in which the corrective maneuvers are cut off at a specified time. The predicted error differential equation is obtained in a way that allows for derivation of several optimal and explicit guidance schemes.

Findings

The effect of tangential acceleration in conjunction with autopilot dynamics can be realized in guidance gain and the predicted error. The differential equation of velocity‐to‐be‐gained is obtained assuming the gravitational acceleration to be given as a vectorial function of time. The relations for different velocity profiles are obtained and discussed including the effective navigation ratio.

Research limitations/implications

The guidance/control system is modeled as a linear time‐varying dynamic and of arbitrary‐order. The gravitational acceleration is assumed as a given vectorial function of time.

Practical implications

The presented schemes are applicable to both midcourse and terminal guidance laws with/without velocity constraints.

Originality/value

Providing a new analytical solution of predicted errors with final position and velocity constraints and their differential equations considering the thrust/drag acceleration and autopilot dynamics in the presence of gravity.

Details

Aircraft Engineering and Aerospace Technology, vol. 80 no. 3
Type: Research Article
ISSN: 0002-2667

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Article
Publication date: 1 September 2006

Hadi Nobahari, Aria Alasty and Seid H. Pourtakdoust

The purpose of this paper is to propose a supervisory command‐to‐line‐of‐sight guidance law with lead angle which keeps the missile flight within the tracking beam.

465

Abstract

Purpose

The purpose of this paper is to propose a supervisory command‐to‐line‐of‐sight guidance law with lead angle which keeps the missile flight within the tracking beam.

Design/methodology/approach

A nonlinear supervisory controller is designed and coupled with the main sliding mode controller in the form of an additional control signal. The supervisory control signal is activated when the beam angle constraint goes to be violated. Initially a supervisory controller is designed using nonlinear control theory. Subsequently the main tracking controller is designed using sliding mode approach which forces the missile to fly along the desired line‐of‐sight. The stability of the supervisory controller coupled with the main controller is proved in the Lyapunov sense.

Findings

There exists a major drawback with the lead angle method of guidance, which is a high probability of flying out of the beam. The proposed supervisory controller has successfully overcome this deficiency. Thus, a better performance has been achieved.

Practical implications

The proposed guidance scheme can be applied to tactical surface to air missiles. Additionally the idea of supervisory controller can be applied to any similar control problem where there are some constrains over the states of the system.

Originality/value

The idea of supervisory controller has not been applied to the problem of command‐to‐line‐of‐sight guidance law. This paper utilizes and extends the idea of supervisory controller design to cases when a special state is to be supervised while considering the effect of external disturbances.

Details

Aircraft Engineering and Aerospace Technology, vol. 78 no. 5
Type: Research Article
ISSN: 0002-2667

Keywords

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Article
Publication date: 15 June 2021

Mohd Badrul Salleh, Nurulasikin Mohd Suhadis and Renuganth Varatharajoo

This paper aims to investigate the attitude control pointing improvement for a small satellite with control moment gyroscopes (CMGs) using the active force control (AFC) method.

74

Abstract

Purpose

This paper aims to investigate the attitude control pointing improvement for a small satellite with control moment gyroscopes (CMGs) using the active force control (AFC) method.

Design/methodology/approach

The AFC method is developed with its governing equations and integrated into the conventional proportional-derivative (PD) controller of a closed-loop satellite attitude control system. Two numerical simulations of an identical attitude control mission namely the PD controller and the PD+AFC controller were carried out using the MATLAB®-SimulinkTM software and their attitude control performances were demonstrated accordingly.

Findings

Having the PD+AFC controller, the attitude maneuver can be completed within the desired slew rate, which is about 2.14 degree/s and the attitude pointing accuracies for the roll, pitch and yaw angles have improved significantly by more than 85% in comparison with the PD controller alone. Moreover, the implementation of the AFC into the conventional PD controller does not cause significant difference on the physical structure of the four single gimbal CMGs (4-SGCMGs).

Practical implications

To achieve a precise attitude pointing mission, the AFC method can be applied directly to the existing conventional PD attitude control system of a CMG-based satellite. In this case, the AFC is indeed the backbone for the satellite attitude performance improvement.

Originality/value

The present study demonstrates that the attitude pointing of a small satellite with CMGs is improved through the implementation of the AFC scheme into the PD controller.

Details

Aircraft Engineering and Aerospace Technology, vol. 93 no. 7
Type: Research Article
ISSN: 1748-8842

Keywords

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Book part
Publication date: 14 November 2006

Ahmad R. Jalali-Naini

Abstract

Details

Explaining Growth in the Middle East
Type: Book
ISBN: 978-0-44452-240-5

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Article
Publication date: 12 January 2010

Giuseppina Autiero and Concetto Paolo Vinci

The purpose of this paper is to analyze the causal link between government regulation of religion and the choice of investing in human and physical capital.

1445

Abstract

Purpose

The purpose of this paper is to analyze the causal link between government regulation of religion and the choice of investing in human and physical capital.

Design/methodology/approach

The paper uses an analytical model with a government setting the output quota to transfer to religious activities. This depends on the extent to which it is an ideological government that uses religion either for legitimacy aims or for the ideological control of population. Workers and entrepreneurs observe the quota and simultaneously choose the investment in human and physical capital, which may trigger, à la Acemoglu, social increasing returns.

Findings

Directing resources to religious activities may be detrimental to output performance. This may occur if an ideological government sets the optimal quota above the quotas preferred by private agents. This negatively affects the investment in physical and human capital and output performance.

Originality/value

Despite the importance of government regulation of religion in the literature, its effect on output performance has not been thoroughly analyzed yet. In this respect, the paper aims to further investigate the causal links between religion regulation related to government type and the investments in human and physical capital and the output level.

Details

International Journal of Social Economics, vol. 37 no. 2
Type: Research Article
ISSN: 0306-8293

Keywords

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Article
Publication date: 7 November 2016

Saurabh Agrawal, Rajesh K. Singh and Qasim Murtaza

The purpose of this paper is to explore the various disposition alternatives and to develop a framework for the optimal disposition decisions in reverse logistics.

1076

Abstract

Purpose

The purpose of this paper is to explore the various disposition alternatives and to develop a framework for the optimal disposition decisions in reverse logistics.

Design/methodology/approach

In reverse logistics, once the products are collected and inspected, decision is to be taken regarding their disposition for reuse, re-manufacture or recycle or other possible alternatives. A combination of analytical hierarchy process (AHP) and fuzzy technique for order preference by similarity to ideal solution (TOPSIS) approach is proposed for the selection of best disposition alternative based on criteria economic benefits, environmental benefits, corporate social responsibility, stakeholder’s needs and reverse logistics resources.

Findings

A case of electronics firm was illustrated for the demonstration of the approach for the disposition of mobile phones. Returned mobile phones must be disposed for repairing or reuse in current business scenario, if possible. Otherwise, the firm may prefer to recycle them rather than dispose or remanufacture.

Research limitations/implications

The study is limited to mobile manufacturing firm. Also, these findings may vary depending on the sector and products. Further, empirical studies and case studies can be carried out to validate the findings.

Practical implications

The proposed framework provides useful tool to the practitioners and researchers in decision-making for disposition in reverse logistics.

Originality/value

Very few studies related to disposition decisions in reverse logistics were found in the previous research literature review. The study will add value to the very limited research on reverse logistics disposition. Also, the AHP-Fuzzy TOPSIS approach is first time being used for the disposition decisions in reverse logistics.

Details

Journal of Modelling in Management, vol. 11 no. 4
Type: Research Article
ISSN: 1746-5664

Keywords

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Book part
Publication date: 14 November 2006

Djavad Salehi-Isfahani

Abstract

Details

Explaining Growth in the Middle East
Type: Book
ISBN: 978-0-44452-240-5

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Article
Publication date: 13 July 2015

Amir Zakery and Abbas Afrazeh

Intangible resources are the most distinctive firms’ assets in competitive environments especially in service businesses. Insurance firms seeking more efficient performance than…

1385

Abstract

Purpose

Intangible resources are the most distinctive firms’ assets in competitive environments especially in service businesses. Insurance firms seeking more efficient performance than competitors should improve their intellectual capital (IC) strategies in both aspects of IC creation and utilization. The purpose of this paper is to investigate and improves IC participation in insurance firms’ efficiency.

Design/methodology/approach

A two-phase framework: “explaining IC role in efficiency” and “measuring efficiencies of IC creation and application” is developed in order to find IC strategies increasing firms’ efficiency and though competitiveness. Efficiency is measured using data envelopment analysis and the generalized estimating equations is used as the regression method in order to explain efficiency with IC measures.

Findings

Empirical results in Iran insurance sector (during a seven-year period for 17 Iranian insurers) show some IC components influence firms’ efficiency and could be intervention points for performance improvement. Then the firms are categorized into four zones in terms of IC efficiency and strategies are recognized for each category.

Research limitations/implications

Although the research is initiated by the need to embed intangible resources in performance improvement in insurance sector, the research framework could be strongly applied in other knowledge-based industries.

Originality/value

This paper embeds an innovative link between classic efficiency and IC which aligns resource management with competitiveness strategies.

Details

Journal of Intellectual Capital, vol. 16 no. 3
Type: Research Article
ISSN: 1469-1930

Keywords

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Article
Publication date: 6 February 2017

Abdolreza Roshani and Farnaz Ghazi Nezami

This paper aims to study a generalized type of mixed-model assembly line with multi-manned workstations where multiple workers simultaneously perform different tasks on the same…

862

Abstract

Purpose

This paper aims to study a generalized type of mixed-model assembly line with multi-manned workstations where multiple workers simultaneously perform different tasks on the same product. This special kind of assembly line is usually utilized to assemble different models of large products, such as buses and trucks, on the same production line.

Design/methodology/approach

To solve the mixed-model multi-manned assembly line balancing problem optimally, a new mixed-integer-programming (MIP) model is presented. The proposed MIP model is nondeterministic polynomial-time (NP)-hard, and as a result, a simulated annealing (SA) algorithm is developed to find the optimal or near-optimal solution in a small amount of computation time.

Findings

The performance of the proposed algorithm is examined for several test problems in terms of solution quality and running time. The experimental results show that the proposed algorithm has a satisfactory performance from computational time efficiency and solution accuracy.

Originality/value

This research is the very first study that minimizes the number of workers and workstations simultaneously, with a higher priority set for the number of workers, in a mixed-model multi-manned assembly line setting using a novel MIP model and an SA algorithm.

Details

Assembly Automation, vol. 37 no. 1
Type: Research Article
ISSN: 0144-5154

Keywords

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Book part
Publication date: 14 November 2006

Jeffrey B. Nugent and M. Hashem Pesaran

Abstract

Details

Explaining Growth in the Middle East
Type: Book
ISBN: 978-0-44452-240-5

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