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Article
Publication date: 31 October 2023

Zhizhong Guo, Fei Liu, Yuze Shang, Zhe Li and Ping Qin

This research aims to present a novel cooperative control architecture designed specifically for roads with variations in height and curvature. The primary objective is to enhance…

Abstract

Purpose

This research aims to present a novel cooperative control architecture designed specifically for roads with variations in height and curvature. The primary objective is to enhance the longitudinal and lateral tracking accuracy of the vehicle.

Design/methodology/approach

In addressing the challenges posed by time-varying road information and vehicle dynamics parameters, a combination of model predictive control (MPC) and active disturbance rejection control (ADRC) is employed in this study. A coupled controller based on the authors’ model was developed by utilizing the capabilities of MPC and ADRC. Emphasis is placed on the ramifications of road undulations and changes in curvature concerning control effectiveness. Recognizing these factors as disturbances, measures are taken to offset their influences within the system. Load transfer due to variations in road parameters has been considered and integrated into the design of the authors’ synergistic architecture.

Findings

The framework's efficacy is validated through hardware-in-the-loop simulation. Experimental results show that the integrated controller is more robust than conventional MPC and PID controllers. Consequently, the integrated controller improves the vehicle's driving stability and safety.

Originality/value

The proposed coupled control strategy notably enhances vehicle stability and reduces slip concerns. A tailored model is introduced integrating a control strategy based on MPC and ADRC which takes into account vertical and longitudinal force variations and allowing it to effectively cope with complex scenarios and multifaceted constraints problems.

Book part
Publication date: 1 August 2004

Henrich R. Greve and Eskil Goldeng

Longitudinal regression analysis is conducted to clarify causal relations and control for unwanted influences from actor heterogeneity and state dependence on theoretically…

Abstract

Longitudinal regression analysis is conducted to clarify causal relations and control for unwanted influences from actor heterogeneity and state dependence on theoretically important coefficient estimates. Because strategic management contains theory on how firms differ and how firm actions are influenced by their current strategic position and recent experiences, consistency of theory and methodology often requires use of longitudinal methods. We describe the theoretical motivation for longitudinal methods and outline some common methods. Based on a survey of recent articles in strategic management, we argue that longitudinal methods are now used more frequently than before, but the use is still inconsistent and insufficiently justified by theoretical or empirical considerations. In particular, strategic management researchers should use dynamic models more often, and should test for the presence of actor effects, autocorrelation, and heteroscedasticity before applying corrections.

Details

Research Methodology in Strategy and Management
Type: Book
ISBN: 978-1-84950-235-1

Open Access
Article
Publication date: 10 November 2023

Chongyi Chang, Gang Guo, Wen He and Zhendong Liu

The objective of this study is to investigate the impact of longitudinal forces on extreme-long heavy-haul trains, providing new insights and methods for their design and…

Abstract

Purpose

The objective of this study is to investigate the impact of longitudinal forces on extreme-long heavy-haul trains, providing new insights and methods for their design and operation, thereby enhancing safety, operational efficiency and track system design.

Design/methodology/approach

A longitudinal dynamics simulation model of the super long heavy haul train was established and verified by the braking test data of 30,000 t heavy-haul combination train on the long and steep down grade of Daqing Line. The simulation model was used to analyze the influence of factors on the longitudinal force of super long heavy haul train.

Findings

Under normal conditions, the formation length of extreme-long heavy-haul combined train has a small effect on the maximum longitudinal coupler force under full service braking and emergency braking on the straight line. The slope difference of the long and steep down grade has a great impact on the maximum longitudinal coupler force of the extreme-long heavy-haul trains. Under the condition that the longitudinal force does not exceed the safety limit of 2,250 kN under full service braking at the speed of 60 km/h the maximum allowable slope difference of long and steep down grade for 40,000 t super long heavy-haul combined trains is 13‰, and that of 100,000 t is only 5‰.

Originality/value

The results will provide important theoretical basis and practical guidance for further improving the transportation efficiency and safety of extreme-long heavy-haul trains.

Details

Railway Sciences, vol. 2 no. 4
Type: Research Article
ISSN: 2755-0907

Keywords

Article
Publication date: 4 October 2022

Mojtaba Labibzadeh, Farhad Bostan Shirin and Amin Khajehdezfuly

This study aims to investigate the effects of using circular spirals as the longitudinal reinforcing bars on the performance of the concrete beams subjected to four-point bending…

Abstract

Purpose

This study aims to investigate the effects of using circular spirals as the longitudinal reinforcing bars on the performance of the concrete beams subjected to four-point bending load.

Design/methodology/approach

The effects of using circular spirals as the longitudinal reinforcing bars on the performance of the concrete beams subjected to four-point bending load are investigated in this study. Employing circular spirals as the main longitudinal reinforcement is a novel idea presented in this paper. In this regard, a finite element model of the beam with spiral longitudinal reinforcement was developed. After model verification, several configurations of concrete beams reinforced by longitudinal spirals were simulated under the four-point loading condition.

Findings

Obtained results showed that using the longitudinal spirals in place of the conventional longitudinal reinforcing bars can improve the bearing capacity of the concrete beam, but at the same time, increases its ductility unacceptably. In other words, the spirals reduce the initial stiffness of the beam significantly. To solve the problem, the authors decided to use the longitudinal spirals as the auxiliary bars added to the main conventional longitudinal bars in the beams. New gained results were satisfactory. By adding the longitudinal spirals to the conventional bars, not only the bearing capacity of the beam increases between 24% and 63%, but also the initial stiffness and ductility of the beam raises between 11%–29% and 3%–57%, respectively, in comparison to the corresponding beam reinforced with conventional longitudinal bars.

Originality/value

Employing circular spirals as the main longitudinal reinforcement is a novel idea presented in this paper.

Details

International Journal of Structural Integrity, vol. 13 no. 6
Type: Research Article
ISSN: 1757-9864

Keywords

Open Access
Article
Publication date: 15 November 2022

Zhiqiang Zhang, Xingyu Zhu and Ronghua Wei

Large displacement misalignment under the action of active faults can cause complex three-dimensional deformation in subway tunnels, resulting in severe damage, distortion and…

Abstract

Purpose

Large displacement misalignment under the action of active faults can cause complex three-dimensional deformation in subway tunnels, resulting in severe damage, distortion and misalignment. There is no developed system of fortification and related codes to follow. There are scientific problems and technical challenges in this field that have never been encountered in past research and practices.

Design/methodology/approach

This paper adopted a self-designed large-scale active fault dislocation simulation loading system to conduct a similar model test of the tunnel under active fault dislocation based on the open-cut tunnel project of the Urumqi Rail Transit Line 2, which passes through the Jiujiawan normal fault. The test simulated the subway tunnel passing through the normal fault, which is inclined at 60°. This research compared and analyzed the differences in mechanical behavior between two types of lining section: the open-cut double-line box tunnel and the modified double-line box arch tunnel. The structural response and failure characteristics of the open-cut segmented lining of the tunnel under the stick-slip part of the normal fault were studied.

Findings

The results indicated that the double-line box arch tunnel improved the shear and longitudinal bending performance. Longitudinal cracks were mainly distributed in the baseplate, wall foot and arch foot, and the crack position was basically consistent with the longitudinal distribution of surrounding rock pressure. This indicated that the longitudinal cracks were due to the large local load of the cross-section of the structure, leading to an excessive local bending moment of the structure, which resulted in large eccentric failure of the lining and formation of longitudinal cracks. Compared with the ordinary box section tunnel, the improved double-line box arch tunnel significantly reduced the destroyed and damage areas of the hanging wall and footwall. The damage area and crack length were reduced by 39 and 59.3%, respectively. This indicates that the improved double-line box arch tunnel had good anti-sliding performance.

Originality/value

This paper adopted a self-designed large-scale active fault dislocation simulation loading system to conduct a similar model test of the tunnel under active fault dislocation. This system increased the similarity ratio of the test model, improved the dislocation loading rate and optimized the simulation scheme of the segmented flexible lining and other key factors affecting the test. It is of great scientific significance and engineering value to investigate the structure of subway tunnels under active fault misalignment, to study its force characteristics and damage modes, and to provide a technical reserve for the design and construction of subway tunnels through active faults.

Details

Railway Sciences, vol. 1 no. 2
Type: Research Article
ISSN: 2755-0907

Keywords

Article
Publication date: 1 December 2008

Suneeta Bhamra, Anthea Tinker, Gill Mein, Richard Ashcroft and Janet Askham

Research that follows people over a period of time (longitudinal or panel studies) is increasingly recognised as of great importance in helping us to understand the ageing process…

Abstract

Research that follows people over a period of time (longitudinal or panel studies) is increasingly recognised as of great importance in helping us to understand the ageing process and changes over time in the lives of older people. If people drop out of studies ‐ which older people are more likely to do ‐ the value of the study diminishes. This research draws on evidence from ongoing and previous longitudinal studies of people aged 55 and over to examine what factors encourage the retention of participants and what causes them to drop out. The research is synthesising existing evidence, drawing together the experiences of researchers involved in longitudinal studies, and collecting some new evidence about the views of survey participants. This article reports on the first part of the research by drawing together evidence from other studies. These show that there are some factors that are related to attrition whereas for others the evidence is mixed. Methods employed by these studies to reduce attrition and retain participants are examined. It must be noted that apart from the consistent finding that attrition is associated with age, education, socio‐economic status and cognitive impairment, not all studies examined the same variables; some only being explored by one study. This makes it difficult to draw any further conclusions and indicates that attrition needs to be addressed in a uniform manner by more studies. This article identifies some implications for policy‐makers and practitioners.

Details

Quality in Ageing and Older Adults, vol. 9 no. 4
Type: Research Article
ISSN: 1471-7794

Keywords

Article
Publication date: 10 July 2007

Ranjan Ganguli, Beatrix Jehnert, Jens Wolfram and Peter Voersmann

To investigate the use of centre of gravity location on reducing cyclic pitch control for helicopter UAV's (unmanned air vehicles) and MAV's (micro air vehicles). Low cyclic pitch…

1078

Abstract

Purpose

To investigate the use of centre of gravity location on reducing cyclic pitch control for helicopter UAV's (unmanned air vehicles) and MAV's (micro air vehicles). Low cyclic pitch is a necessity to implement the swashplateless rotor concept using trailing edge flaps or active twist using current generation low authority piezoceramic actuators.

Design/methodology/approach

An aeroelastic analysis of the helicopter rotor with elastic blades is used to perform parametric and sensitivity studies of the effects of longitudinal and lateral center of gravity (cg) movements on the main rotor cyclic pitch. An optimization approach is then used to find cg locations which reduce the cyclic pitch at a given forward speed.

Findings

It is found that the longitudinal cyclic pitch and lateral cyclic pitch can be driven to zero at a given forward speed by shifting the cg forward and to the port side, respectively. There also exist pairs of numbers for the longitudinal and lateral cg locations which drive both the cyclic pitch components to zero at a given forward speed. Based on these results, a compromise optimal cg location is obtained such that the cyclic pitch is bounded within ±5° for a BO105 helicopter rotor.

Originality/value

The reduction in the cyclic pitch due to helicopter cg location is found to significantly reduce the maximum magnitudes of the control angles in flight, facilitating the swashplateless rotor concept. In addition, the existence of cg locations which drive the cyclic pitches to zero allows for the use of active cg movement as a way to replace the cyclic pitch control for helicopter MAV's.

Details

Aircraft Engineering and Aerospace Technology, vol. 79 no. 4
Type: Research Article
ISSN: 0002-2667

Keywords

Article
Publication date: 25 May 2012

Markku Kuula and Antero Putkiranta

The purpose of this paper is to explore the possibilities and pitfalls of longitudinal studies in the field of operations management (OM).

1149

Abstract

Purpose

The purpose of this paper is to explore the possibilities and pitfalls of longitudinal studies in the field of operations management (OM).

Design/methodology/approach

A longitudinal study conducted in Finland was analyzed from the methodological point of view. In the theoretical part, a framework for analyses was created by studying the literature of longitudinal studies within and without the OM field.

Findings

Longitudinal studies are important in revealing root‐cause effects. They are particularly important in generating new ideas and theories and in questioning old ones. However, longitudinal studies are somewhat difficult to conduct and some unexpected challenges may arise, such as the effect of technology development on data retrieval.

Research limitations/implications

The analyses in this study are based on the data obtained in a longitudinal study conducted in the years 1993, 2004 and 2010. The sample in the longitudinal study is quite small for real quantitative statistical analysis, and therefore the conclusions made here are only indicative. However, the purpose of this study is to give some hints and guidance, and thus the lessons learned are valuable.

Originality/value

There are only a few studies describing methodological issues in longitudinal studies in the field of OM, and most of these studies are purely theoretical and do not refer to real experiences. This appears to be one of the first studies describing real experiences from a longitudinal study.

Details

Benchmarking: An International Journal, vol. 19 no. 3
Type: Research Article
ISSN: 1463-5771

Keywords

Book part
Publication date: 25 January 2021

Desalegn Abraha and Akmal S. Hyder

The method applied to carry out the study of the transformation of strategic alliances in emerging markets is discussed in this chapter. Specifically, this chapter discusses how…

Abstract

The method applied to carry out the study of the transformation of strategic alliances in emerging markets is discussed in this chapter. Specifically, this chapter discusses how the whole study is conducted, i.e. the identification and development of the research issues, the research aim and problem, the development of the conceptual framework, the development of the research method, how the empirical study is analyzed and conclusions are drawn. The specific research strategy applied to conduct the current study is a longitudinal research approach. A short discussion on how the ECE countries are classified into various groups is conducted in the current chapter and a detailed discussion on the classification of ECE countries into different groups is also conducted in chapter eight. Moreover, the logic for adopting a longitudinal research strategy to conduct the current study of the transformation of strategic alliances is also justified. The identification and choice of the case companies, the logic followed in the development of the questionnaire and how much and to what extent the questionnaire is modified are also discussed in detail. The identification of the interviewees, the execution of the interviews and the transcription of the interview materials and the structuring of the cases are also discussed in detail.

Details

Transformation of Strategic Alliances in Emerging Markets, Volume I
Type: Book
ISBN: 978-1-80043-745-6

Book part
Publication date: 28 August 2007

Michael C. Sturman

This article reviews the extensive history of dynamic performance research, with the goal of providing a clear picture of where the field has been, where it is now, and where it…

Abstract

This article reviews the extensive history of dynamic performance research, with the goal of providing a clear picture of where the field has been, where it is now, and where it needs to go. Past research has established that job performance does indeed change, but the implications of this dynamism and the predictability of performance trends remain unresolved. Theories are available to help explain dynamic performance, and although far from providing an unambiguous understanding of the phenomenon, they offer direction for future theoretical development. Dynamic performance research does suffer from a number of methodological difficulties, but new techniques have emerged that present even more opportunities to advance knowledge in this area. From this review, I propose research questions to bridge the theoretical and methodological gaps of this area. Answering these questions can advance both research involving job performance prediction and our understanding of the effects of human resource interventions.

Details

Research in Personnel and Human Resources Management
Type: Book
ISBN: 978-0-7623-1432-4

1 – 10 of over 62000