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Article
Publication date: 18 May 2010

M.N. Filipski and R. Varatharajoo

This paper aims to present the development and performance evaluation of an attitude and rate estimation algorithm using an extended Kalman filter structure based on a…

434

Abstract

Purpose

This paper aims to present the development and performance evaluation of an attitude and rate estimation algorithm using an extended Kalman filter structure based on a body‐referenced representation of the state.

Design/methodology/approach

The algorithm requires only geomagnetic field data and can be used as a low‐cost alternative or as a back‐up estimator in the case of attitude sensor failures. The satellite rate is estimated as a part of the filter state and thus no gyroscope is necessary. The assessment of the algorithm performance is realized through a Monte Carlo simulation using a low‐Earth orbit, nadir‐pointing satellite.

Findings

Given some attitude and rate error requirements, the range of admissible initial errors on the filter state and the effect of un‐modelled disturbance torque are determined, along with the achievable attitude and rate accuracies.

Practical implications

Because the simulation set‐up is clearly stated, the results of this evaluation can be used as a benchmark for other estimation algorithms.

Originality/value

The necessary assumptions and approximations used to derive the filter equations are explicitly pointed out for the benefit of the readers. Well‐defined filter initial conditions are used in an extensive series of tests resulting into a unique set of findings.

Details

Aircraft Engineering and Aerospace Technology, vol. 82 no. 3
Type: Research Article
ISSN: 0002-2667

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Article
Publication date: 19 February 2020

Feng Cui, Dong Gao and Jianhua Zheng

The main reason for the low accuracy of magnetometer-based autonomous orbit determination is the coarse accuracy of the geomagnetic field model. Furthermore, the geomagnetic field…

150

Abstract

Purpose

The main reason for the low accuracy of magnetometer-based autonomous orbit determination is the coarse accuracy of the geomagnetic field model. Furthermore, the geomagnetic field model error increases obviously during geomagnetic storms, which can still further reduce the navigation accuracy. The purpose of this paper is to improve the accuracy of magnetometer-based autonomous orbit determination during geomagnetic storms.

Design/methodology/approach

In this paper, magnetometer-based autonomous orbit determination via a measurement differencing extended Kalman filter (MDEKF) is studied. The MDEKF algorithm can effectively remove the time-correlated portion of the measurement error and thus can evidently improve the accuracy of magnetometer-based autonomous orbit determination during geomagnetic storms. Real flight data from Swarm A are used to evaluate the performance of the MDEKF algorithm presented in this study. A performance comparison between the MDEKF algorithm and an extended Kalman filter (EKF) algorithm is investigated for different geomagnetic storms and sampling intervals.

Findings

The simulation results show that the MDEKF algorithm is superior to the EKF algorithm in terms of estimation accuracy and stability with a short sampling interval during geomagnetic storms. In addition, as the size of the geomagnetic storm increases, the advantages of the MDEKF algorithm over the EKF algorithm become more obvious.

Originality/value

The algorithm in this paper can improve the real-time accuracy of magnetometer-based autonomous orbit determination during geomagnetic storms with a low computational burden and is very suitable for low-orbit micro- and nano-satellites.

Details

Aircraft Engineering and Aerospace Technology, vol. 92 no. 3
Type: Research Article
ISSN: 1748-8842

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Article
Publication date: 3 May 2013

Li Fu, Lingling Wang and Jianghai Hu

The aim of this paper is to propose a new coning correction algorithm, based on the singular perturbation technique, for the attitude update computation with non‐ideal angular…

244

Abstract

Purpose

The aim of this paper is to propose a new coning correction algorithm, based on the singular perturbation technique, for the attitude update computation with non‐ideal angular rate information.

Design/methodology/approach

Unlike conventional coning correction algorithms, the new method uses angular rate two‐time scale model to construct the coning correction term of attitude update. In order to achieve balanced real/pseudo coning correction performance, the selection guidelines of the new algorithm parameters are established.

Findings

Performance of the new algorithm is evaluated by comparison with the conventional algorithm in no ideal sensors undergoing stochastic coning environments. The accuracy of attitude update can be improved effectively with reduced computational workload by using this new coning algorithm as compared with conventional ones.

Practical implications

The proposed coning correction algorithm can be implemented with angular rate sensors in UAV (unmanned aerial vehicle) and other aircrafts attitude estimation for navigation and control applications.

Originality/value

Singular perturbation is an effective method for structuring coning correction algorithm with filtered angular rate outputs in stochastic coning environments. The improved coning correction algorithm based on singular perturbations reduces the real and pseudo coning effects effectively as compared with conventional ones. It is proved to be valid for improvement of accuracy with reduced computations of the attitude update.

Details

Aircraft Engineering and Aerospace Technology, vol. 85 no. 3
Type: Research Article
ISSN: 0002-2667

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Article
Publication date: 1 November 2021

Yixing Zhang, Xiaomeng Lu, Haitao Yin and Rui Zhao

Scholars have not agreed with each other on how people would behave after experiencing a catastrophic event. They could save more as a precautionary action for future difficulties…

441

Abstract

Purpose

Scholars have not agreed with each other on how people would behave after experiencing a catastrophic event. They could save more as a precautionary action for future difficulties or save less with a carpe diem attitude. This study aims to attempt to shed light on this debate with empirical observations on how the Covid-19 pandemic has affected household saving decisions.

Design/methodology/approach

The two waves of the survey data allowed us to investigate both instantaneous and ongoing effects of Covid-19 on household saving decisions. The instantaneous effect refers to the immediate impact of the crisis, while the ongoing effect refers to the lasting impact of the pandemic when economic recovery had started. The variation in the number of confirmed cases across cities during the two waves provides the source of power for identification. The authors extend their analyses of the impact of Covid-19 on the household saving decision by using ordinary least squares models. Due to the ordered nature of survey responses, the authors also rerun all baseline models using the ordered probit regression method.

Findings

This paper studied the impact of the Covid-19 pandemic on household saving decisions in China. This study found that households in the most affected cities would save more during the Covid-19 but tend to save less when the disaster started fading away. Combining findings in Kun et al. (2013) and Filipski et al. (2015), people do become more pessimistic during and after the Covid-19, possibly driving their observed precautionary and cape diem behaviors during the two points of time. Heterogeneity analysis shows that specific households would dramatically change their saving behavior. These observations might be useful for policymakers who concern the economic recovery after this pandemic disaster.

Originality/value

Understanding how the Covid-19 pandemic would affect household consumption vs saving decisions is important for the economic recovery after this disaster comes to an end. The analyses presented in this research could be useful for policymakers who concern appropriate policies aiming to boost consumption and economic activities after Covid.

Details

China Finance Review International, vol. 13 no. 3
Type: Research Article
ISSN: 2044-1398

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Article
Publication date: 1 April 2019

Narinder Kumar and Ashwani Kumar

The purpose of this paper is to analyze annual energy expenditure in the presence of non-linear load and substation voltage harmonics in distribution systems. Economic assessment…

67

Abstract

Purpose

The purpose of this paper is to analyze annual energy expenditure in the presence of non-linear load and substation voltage harmonics in distribution systems. Economic assessment of non-sinusoidal energy is a challenging task that involves complex computations of harmonic load powers and harmonic line losses.

Design/methodology/approach

The paper evaluates fundamental and non-sinusoidal components of electrical energy by applying backward/forward sweep technique in distorted distribution systems. This work involves harmonic power computations at the substation by including harmonic losses occurring in various lines of the distribution system.

Findings

The paper found that annual energy expenditure significantly depends upon the non-linear load, supply voltage harmonics and type of tariff structure considered in the distribution system. Impact of individual harmonic orders on the energy billing is also assessed.

Originality/value

The paper concludes that considering harmonic distortions in the distribution system analysis would help electricity regulators formulate adequate pricing structures, which would further generate appropriate economic signals for electricity utility and the consumers.

Details

International Journal of Energy Sector Management, vol. 13 no. 1
Type: Research Article
ISSN: 1750-6220

Keywords

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Article
Publication date: 29 October 2021

Fikri Zul Fahmi and Medina Savira

This paper aims to identify how digitalization affects entrepreneurial attitudes in rural areas in Indonesia, a country in the Global South. The development of digital technology…

1152

Abstract

Purpose

This paper aims to identify how digitalization affects entrepreneurial attitudes in rural areas in Indonesia, a country in the Global South. The development of digital technology can help entrepreneurs, in that faster and easier information acquisition helps rural communities to identify new opportunities and innovate. Yet, digital development generates higher disparity, and thus, not all people can benefit from digitalization. Although digital technology can facilitate the development of entrepreneurship, its benefits depend on individual preferences. In this regard, the capability approach is used so as to reflect how different valuations of digital technology in rural entrepreneurs influence their attitude with regard to recognizing business opportunities and taking risks.

Design/methodology/approach

A double case study approach is used in which this study examines two cases of rural entrepreneurs in Indonesia that represent different uses of digital technologies and socio-economic rural contexts: coffee entrepreneurs in Kintamani and craft producers in Kamasan village. In so doing, semi-structured interviews were conducted with local entrepreneurs and communities according to purposive and snowball sampling techniques. The qualitative data were then analysed using a constant comparative technique which allows us to develop a conceptual argument by observing patterns within and between the cases.

Findings

The findings show that digitalization shapes the attitude of rural entrepreneurs differently, although the same opportunity from using digital technology is present in the village. Social and environmental factors facilitate the rural entrepreneurs to consider using digital technology to develop their businesses. However, as each individual entrepreneur has a different valuation of digital technology, the benefits it offers – such as broader market opportunities and new business ideas – vary. Entrepreneurs who consider digital technology to be a valuable resource for developing their businesses are more curious to explore its benefits.

Originality/value

The capability approach provides a new perspective in understanding rural entrepreneurship. First, the authors demonstrate that the success of rural entrepreneurship is influenced not only by concrete things (e.g. resources) but also the individual perspective on these resources which may vary across entrepreneurs. Second, the authors show not only the potential differences in socio-cultural contexts in which the capability approach is applied but also how socio-cultural values and collectivism influence the individual valuation of resources that could benefit entrepreneurs.

Details

Journal of Enterprising Communities: People and Places in the Global Economy, vol. 17 no. 2
Type: Research Article
ISSN: 1750-6204

Keywords

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Article
Publication date: 26 August 2014

Sheng Li, Yaoqi Zhang, Denis Nadolnyak, John David Wesley and Yifei Zhang

Since 2004, subsidies increased by 670 percent in the Chinese fertilizer industry to reduce the farmer's burden. The purpose of this paper is to assess whether subsidies benefit…

651

Abstract

Purpose

Since 2004, subsidies increased by 670 percent in the Chinese fertilizer industry to reduce the farmer's burden. The purpose of this paper is to assess whether subsidies benefit the target groups, the fertilizer subsidy distribution pattern and benefit allocation pattern among fertilizer producers and other sectors were investigated.

Design/methodology/approach

The Muth model is extended to evaluate the impacts of a subsidy on multi-stage markets.

Findings

It is found that the total benefits from the policy are about RMB 7.7 billion yuans. The fertilizer suppliers gain about RMB 51 billion yuans from the favorable policy with mean subsidy incidence 0.8 and capturing about 70 percent of total surplus.

Social implications

The results suggest that transferring parts of subsidies to the non-fertilizer sectors could be considered an efficient way to redistribute welfare indifferent sectors.

Originality/value

This study first use the equilibrium displacement model to quantity the distribution of fertilizer subsidy in a vertical market in China.

Details

China Agricultural Economic Review, vol. 6 no. 3
Type: Research Article
ISSN: 1756-137X

Keywords

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Article
Publication date: 14 May 2018

Arief Anshory Yusuf

The purpose of this paper is to analyze the impact of unconditional cash transfers in Indonesia on poverty and inequality while, unlike much of the previous literature on the…

1029

Abstract

Purpose

The purpose of this paper is to analyze the impact of unconditional cash transfers in Indonesia on poverty and inequality while, unlike much of the previous literature on the welfare impact of such transfers, acknowledging that they will have both a direct effect and an economy-wide effect on the national economy.

Design/methodology/approach

The methodology used is a Computable General Equilibrium (CGE) model of the Indonesian economy. The unique feature of this model, which is very relevant in this study, is the disaggregation of households by expenditure classes; this allows for precise estimation of the distributional impact and poverty incidence.

Findings

The results suggest that, despite a large reduction in poverty, particularly in rural areas, such transfers reduce the Indonesian GDP, especially if domestically financed through increasing the value added tax of all commodities. However, the GDP reduction can be reduced by approximately half when cash transfers are financed by reducing the distortionary fuel subsidy. Moreover, cash transfers financed by reducing the fuel subsidy also reduce inequality by much more than otherwise. Various extents of the distribution of the transfers are compared, from giving them to the poorest 10 percent to distributing them equally to all households. The benefit of the transfers, in terms of reduced poverty and inequality, is found to be smaller when the author extends the beneficiaries toward the non-poor, although the economy-wide cost, in terms of the reduced GDP, is smaller.

Research limitations/implications

The CGE model used in this model is a comparative-static model that does not explicitly model the time dimension, i.e. how the impact of the transfers evolves over time. This is important if we want to know the timing of the transfers and how and when they are translated into impacts.

Practical implications

To reduce the contractionary effect of cash transfers program, government/policy makers should carefully look for appropriate financing such as from removing subsidy with pre-existing distortions like fuel subsidies.

Social implications

Government needs to carefully design cash transfers to minimize the negative indirect (economy-wide) implication for the national economy and to make sure that the transfers reach the targeted beneficiaries.

Originality/value

Few previous studies have acknowledged the indirect economy-wide effect in analyzing the impact of cash transfers. To the author’s knowledge, this has never been done before for Indonesia. Unlike previous studies, this paper is unique as it contains sensitivity analysis on how transfers can be mistargeted and reach the non-poor and looks at the implications not only for poverty and inequality but also for the rest of the economy.

Details

International Journal of Social Economics, vol. 45 no. 5
Type: Research Article
ISSN: 0306-8293

Keywords

Available. Open Access. Open Access
Article
Publication date: 27 November 2023

Siddig Hussein Hamad

The purpose of this article is to investigate on changes of the microbial load and the chemical and physical properties of date fruits stored for 6 months under two different…

735

Abstract

Purpose

The purpose of this article is to investigate on changes of the microbial load and the chemical and physical properties of date fruits stored for 6 months under two different temperatures.

Design/methodology/approach

A composite sample of 100 kg date fruits from the Khalas variety, season 2019, was collected from the local market in Al Ahsa Province, Saudi Arabia, packaged in 1 kg lots, stored at room and refrigerator temperatures and the microbial contamination and the chemical and physical properties monitored over a period of six months of storage. Total bacteria, lactic acid bacteria, Enterobacteriaceae, yeasts and molds were counted and representatives of yeast and mold contaminants were identified using morphological, physiological and molecular typing techniques. Changes in the color and texture of the samples were also monitored during storage.

Findings

The yeasts detected were two strains of each of Lachancea thermotolerans and Rhodosporidiobolus fluvialis and one strain of Cystofilobasidium lacus-mascardii. For molds, one strain of each of Aspergillus niger, Aspergillus flavus, Penicillium chrysogenum and Aspergillus caespitosus have been detected. No significant growth of these microorganisms was observed, but enough load persisted during storage that makes the samples not meeting the microbiological standards. There were significant changes in the color and texture of the fruits during storage.

Originality/value

These findings add important information that can help producers and processors to improve quality and promote marketing of date fruits, especially to international markets.

Details

Arab Gulf Journal of Scientific Research, vol. 42 no. 4
Type: Research Article
ISSN: 1985-9899

Keywords

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Article
Publication date: 4 July 2016

Jose Caraballo-Cueto

The Dominican trade deficit represents almost 16 per cent of its gross domestic product (GDP) and is insufficiently counteracted by tourism and remittances; not even a high…

668

Abstract

Purpose

The Dominican trade deficit represents almost 16 per cent of its gross domestic product (GDP) and is insufficiently counteracted by tourism and remittances; not even a high devaluation closed the imbalance. Eighty per cent of the exports are from free trade zones. These facts reflect their low domestic entrepreneurial capacity. The purpose of this study is to critically evaluate the Dominican economic model.

Design/methodology/approach

The author motivates the discussion with descriptive statistics and then applies multiple time-series regressions at the macro level and at the industry level.

Findings

The attraction of foreign firms appears to substitute, and not complement, the building of local capacity. Regressions show that a GDP growth of 5 per cent does not decrease the high unemployment rate.

Originality/value

Using new Okun’s equations, it is concluded that sectors dominated by local producers and improvements in the trade balance better impact the unemployment. These findings challenge conventional wisdom that characterizes the Dominican economy as a “successful story”.

Details

International Journal of Development Issues, vol. 15 no. 2
Type: Research Article
ISSN: 1446-8956

Keywords

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