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Article
Publication date: 5 April 2024

Heping Liu, Jinxin Lu, Fusheng Zhu and Ani Luo

This study proposes a tensegrity-based traction structure with D-bar dual cable units. It is used to connect the airship and the ground to stabilize the airship.

Abstract

Purpose

This study proposes a tensegrity-based traction structure with D-bar dual cable units. It is used to connect the airship and the ground to stabilize the airship.

Design/methodology/approach

The mathematical models and dynamic models of the D-bar dual cable (hereafter referred to as DD cable) unit of the tensegrity-based traction structure are established. Based on the minimum mass method, the mass of the DD cable unit in the critical state (cable member is yielding, or bar member is buckling or yielding) is analyzed. Then, the tensile strength of the DD cable unit and single cable unit under the same condition is compared using the control variate method. Finally, based on ANSYS dynamic simulation, the stability of the two structures under the same external force disturbance was tested.

Findings

Expressions for the minimum mass of the DD cable unit under different failure conditions are solved. Dynamic simulation results show that the capacity of resisting disturbance of the DD cable unit is much better than that of the single cable unit under the same wind speed. So, we find a structure more suitable for the fixed connection of an airship.

Originality/value

This study helps to provide theoretical reference and thinking for the practical application of the traction structure with a D-bar dual cable unit.

Details

Engineering Computations, vol. 41 no. 2
Type: Research Article
ISSN: 0264-4401

Keywords

Article
Publication date: 3 April 2024

Erol Can and Ugur Kilic

Static inverters are very important for the emergency energy distribution system of aircraft and similar machines. At the same time, the electrical energy produced at high…

Abstract

Purpose

Static inverters are very important for the emergency energy distribution system of aircraft and similar machines. At the same time, the electrical energy produced at high frequency for electrical devices is used to reduce the weight of the cables in the aircraft and spacecraft because of the skin effect. In the high-frequency system, a thinner cable cross-section is used, and a great weight reduction occurs in the aircraft. So, fuel economy, less and late wear of the materials (landing gear, etc.) can be obtained with decreasing weight. This paper aims to present the development of a functional multilevel inverter (FMLI) with fractional sinus pulse width modulation (FSPWM) and a reduced number of switches to provide high-frequency and quality electrical energy conversion.

Design/methodology/approach

After the production of FSPWM for FMLI with a reduced component, which, to the best of the authors’ knowledge, is presented for the first time in this study, is explained step by step, and eight operating states are given according to different FSPWMs operating the circuit. The designed inverter and modulation technique are compared by testing the conventional modular multilevel inverter on different loads.

Findings

According to application results, it is seen that there is a 50% reduction in cross-section from 100 Hz to 400 Hz with the skin effect. At 1000 Hz, there is a 90% cross-section reduction. The decrease can be in cable weights that may occur in aircraft from 10 kg to 100 kg according to different frequencies. It causes less harmonic distortion than conventional converters. This supports the safer operation of the system. Compared to the traditional system, the proposed system provides more amplitude in converting the source to alternating voltage and increases the efficiency.

Practical implications

FSPWM is developed for multilevel inverters with reduced components at the high frequency and cascaded switching studies in the power electronics of aircraft.

Social implications

Although the proposed system has less current and power loss as mentioned in the previous sections, it contains fewer power elements than conventional inverters that are equivalent for different hardware levels. This not only reduces the cost of the system but also provides ease of maintenance. To reduce the cable load in aircraft and create more efficient working conditions, 400 Hz alternative voltage is used. The proposed system causes less losses and lower harmonic distortions than traditional systems. This will reduce possible malfunctions and contribute to aircraft reliability for passengers and cargo. As technology develops, it is revealed that the proposed inverter system will be more efficient than traditional inverters when devices operating at frequencies higher than 400 Hz are used. With the proposed inverter, safer operation will be ensured, while there will be less energy loss, less fuel consumption and less carbon emissions to the environment.

Originality/value

The proposed inverter structure shows that it can provide energy transmission for electrical devices in space and aircraft by using the skin effect. It also contains less power elements than the traditional inverters, which are equivalent for different levels of hardware.

Details

Aircraft Engineering and Aerospace Technology, vol. 96 no. 3
Type: Research Article
ISSN: 1748-8842

Keywords

Article
Publication date: 2 April 2024

Jane Andrew and Max Baker

This study explores a hegemonic alliance and the role of relational forms of accounting and accountablity in the making of contemporary capitalism.

Abstract

Purpose

This study explores a hegemonic alliance and the role of relational forms of accounting and accountablity in the making of contemporary capitalism.

Design/methodology/approach

We use the WikiLeaks “Cablegate” documents to provide an account of the detailed machinations between interest groups (corporations and the state) that are constitutive of hegemonic activity.

Findings

Our analysis of the “Cablegate” documents shows that the US and Chevron were crafting a central role for Turkmenistan and its president on the global political stage as early as 2007, despite offical reporting beginning only in 2009. The documents exemplify how “accountability gaps” occlude the understanding of interdependence between capital and the state.

Research limitations/implications

The study contributes to a growing idea that official accounts offer a fictionalized narrative of corporations as existing independently, and thus expands the boundaries associated with studying multinational corporate activities to include their interdependencies with the modern state.

Social implications

The study traces how global capitalism extends into new territories through diplomatic channels, as a strategic initiative between powerful state and capital interests, arguing that the outcome is the empowerment of authoritarian states at the cost of democracy.

Originality/value

The study argues that previous accounting and accountability research has overlooked the larger picture of how capital and the state work together to secure a mutual hegemonic interest. We advocate for a more complete account of these activities that circumvents official, often restricted, views of global capitalism.

Details

Accounting, Auditing & Accountability Journal, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 0951-3574

Keywords

Book part
Publication date: 28 March 2024

Sonia Virginia Moreira, Nélia R. Del Bianco and Cézar F. Martins

The expansion of connectivity on a national scale in Brazil, whether through mobile Internet or fixed broadband, is described as one of the factors that can lead to social and…

Abstract

The expansion of connectivity on a national scale in Brazil, whether through mobile Internet or fixed broadband, is described as one of the factors that can lead to social and economic benefits for large parts of the population who do not have a network connection. It can also help to reduce poverty by improving the infrastructure of services and increasing Internet use for education purposes. It also provides people with the ability to communicate with online administrative services – local, regional, and national. In Brazil, the main difficulty facing an effective universalization of telecommunications has been limitations in accessing services. This chapter demonstrates the relevance of small Internet providers for the expansion of fixed broadband in less commercially attractive regions (in terms of subscribers, income, and distance) who have been growing over recent years and are now present in 70% of Brazilian municipalities and whose role is paramount to reducing the digital divide.

Details

Geo Spaces of Communication Research
Type: Book
ISBN: 978-1-80071-606-3

Keywords

Article
Publication date: 5 June 2023

Takumi Yamaguchi and Fuminobu Ozaki

The main purpose of this study was to evaluate the tensile strengths of JIS G3549 super high-strength steel strand wire ropes (1,570 MPa-class high-carbon steels) and wire rope…

42

Abstract

Purpose

The main purpose of this study was to evaluate the tensile strengths of JIS G3549 super high-strength steel strand wire ropes (1,570 MPa-class high-carbon steels) and wire rope open swaged socket connections at fire and post fire.

Design/methodology/approach

Steady-state tests from ambient temperature (20 °C) to 800 °C, transient-state tests under the allowable design tensile force and tensile tests in an ambient temperature environment after heating (heating temperatures of 200–800 °C) were conducted.

Findings

The tensile strengths of the wire rope and end-connection specimens at both fire and post fire were obtained. The steel wire rope specimens possessed larger reduction factors than general hot-rolled mild steels (JIS SS400) and high-strength steel bolts (JIS F10T). The end-connection specimens with sufficient socket lengths exhibited ductile fracture of the wire rope part at both fire and post fire; however, those with short socket lengths experienced a pull-out fracture at the socket.

Originality/value

The fundamental and important tensile test results of the super high-strength steel strand wire ropes (1,570 MPa-class high-carbon steels) and wire rope open swaged socket connections were accumulated at fire and post fire, and the fracture modes were clarified. The obtained test results contribute to fire resistance performance-based design of cable steel structures at fire and fire-damage investigations to consider their reusability post fire.

Article
Publication date: 24 April 2024

Hangyue Zhang, Yanchu Yang and Rong Cai

This paper aims to present numerical simulations for a series of flight processes for the postlaunching stage of the “balloon-borne UAV system.” It includes the balloon further…

Abstract

Purpose

This paper aims to present numerical simulations for a series of flight processes for the postlaunching stage of the “balloon-borne UAV system.” It includes the balloon further ascent motion after airborne launching. In terms of unmanned aerial vehicles (UAVs), the tailspin state and the charge-out process with an anti-tailspin parachute-assisted suspending are analyzed. Then, the authors conduct trajectory optimization simulations for the long-distance gliding process.

Design/methodology/approach

The balloon kinematics model and the parachute Kane multibody dynamic model are established. Using steady-state tailspin to reduced-order analysis and achieving change-out simulation by parachute suspension dynamic model. A reentry optimization control problem is developed and the Radau pseudo-spectral method is used to calculate the glide trajectory.

Findings

The established dynamic model and trajectory optimization method can effectively simulate the motion process of balloons and UAVs. The system mass reduction for launching UAVs will not cause damage to the balloon structure. The anti-tailspin parachute can reduce the UAV attack angles effectively. The UAV can glide to the designated target position by adjusting the attack angle and sideslip angle. The farthest flight distance after launching from 20 km height is 94 km and the gliding time is 40 min, which demonstrates the potential application advantage of high-altitude launching.

Practical implications

The research content and related conclusions of this article achieve a closed-loop analysis of the flight mission chain for the “balloon-borne UAV system,” which provides simulation references for relevant balloon launching experiments.

Originality/value

This paper establishes a complete set of numerical simulation models and can effectively analyze various postlaunching behaviors.

Details

Aircraft Engineering and Aerospace Technology, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 1748-8842

Keywords

Article
Publication date: 18 May 2023

Brian Gregory

This study aims to explore a rarely studied form of person–organization fit, perceptual fit, which captures the accuracy of an employee’s understanding of their organization’s…

Abstract

Purpose

This study aims to explore a rarely studied form of person–organization fit, perceptual fit, which captures the accuracy of an employee’s understanding of their organization’s culture. The managerial antecedents of perceptual fit were explored to increase understanding about how employees learn their organizational culture and the role that managers play in that process. In addition, the behavioural and attitudinal consequences of perceptual fit were examined to gain a deeper appreciation for the impact of misunderstanding one’s organizational culture on work attitudes and cognitions.

Design/methodology/approach

Survey tools were used to measure multiple workplace cognitions, attitudes and values from employees of three small health-care organizations. Organizational culture was measured for each organization so that perceptual fit could be ascertained, which represents an accuracy score of each individual’s comprehension of their organization’s culture. Regression analyses measured the hypothesized associations between perceptual fit and its proposed antecedents and consequences.

Findings

The results suggest that leader–member exchange (LMX) and perceived organizational support (POS) are both positively associated with perceptual fit. In terms of the outcomes of perceptual fit, the regression analyses provide support for an association between perceptual fit and psychological empowerment, job satisfaction and organizational commitment.

Originality/value

This study contributes to the literature by exploring how employees come to understand their organization’s culture, and the consequences of differing levels of understanding (i.e. perceptual fit). The study results suggest that managerial action such as LMX and POS can enhance the chances that an employee is able to understand their organization’s culture accurately. Furthermore, this research adds to our understanding of the individual consequences of understanding one’s organizational culture by providing evidence that psychological empowerment is associated with perceptual fit.

Details

International Journal of Organizational Analysis, vol. 32 no. 4
Type: Research Article
ISSN: 1934-8835

Keywords

Case study
Publication date: 24 April 2024

Stephen E. Maiden

This case teaches students the importance of maintaining a strong FICO score by illustrating the consequences of paying bills late or not at all. The protagonist is David Molina…

Abstract

This case teaches students the importance of maintaining a strong FICO score by illustrating the consequences of paying bills late or not at all. The protagonist is David Molina, a waiter at a struggling Italian restaurant located down the block from where he lives. Money is tight for Molina right now—his limited income means he lives paycheck to paycheck. However, Molina knows things will be looking up for him soon because he recently accepted a job as a bank teller across town—his first desk job.

Molina has been putting off paying two of his bills: a cable bill and his Bank of America credit card bill, both of which are late and have been issued, this time, in the form of threats to impact Molina's credit score if he doesn't pay them. He has just enough money to afford the minimum payments on each overdue bill. But then he receives a phone call from his friend, Jim Lindsey, reminding him about an invitation to go to Myrtle Beach for the upcoming weekend. Molina knows he cannot afford it, but a woman he's attracted to, Jessica, will be there too. Should Molina put off the bills yet again, and if so, how exactly will being late on them hurt his credit score?

Details

Darden Business Publishing Cases, vol. no.
Type: Case Study
ISSN: 2474-7890
Published by: University of Virginia Darden School Foundation

Keywords

Executive summary
Publication date: 15 March 2024

WEST AFRICA: Internet outages could affect economy

Details

DOI: 10.1108/OXAN-ES285883

ISSN: 2633-304X

Keywords

Geographic
Topical
Article
Publication date: 18 December 2023

Anuradha Mitra, V. Sridhar and Gopal K. Sarangi

This paper aims to draw lessons for telecommunications (telecom) network deployment in India, from a study of policy and regulatory approaches taken by other federal…

Abstract

Purpose

This paper aims to draw lessons for telecommunications (telecom) network deployment in India, from a study of policy and regulatory approaches taken by other federal administrations in streamlining processes for site clearances, grant of rights of way (RoW) and approvals for local infrastructure deployment and sharing. With the urgent need for setting up small cells and rapid fiberisation of networks in the 5G era, the importance of such processes has gained prominence.

Design/methodology/approach

The authors adopt qualitative thematic content analysis with three-tier coding and classification to identify themes in archival and current documentary data and information obtained from subject-matter experts in the countries studied.

Findings

Formulation and implementation of telecom policy is led by national governments. However, national telecom administrations, in recognition of new needs, have co-opted states and local authorities as partners in development of telecom networks, providing the overall framework, guidance and appropriate incentives where required.

Practical implications

This cooperative model could work well in India, where telecom policy making and regulation is the prerogative of the central government, but administration of RoW and local clearances for cable laying, tower siting and associated infrastructure activities for expanding telecom networks are left to decentralised decision-making in the states and local bodies.

Originality/value

This research attempts to sytematise, thematise and draw cross-country comparisons to inform regulatory and administrative policy for 5G infrastructure rollout in India.

1 – 10 of 213