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11 – 20 of over 1000Reports on the MSc group design project of students at the College of Aeronautics, Cranfield University. Details the design of the aircraft systems and their reliability and…
Abstract
Reports on the MSc group design project of students at the College of Aeronautics, Cranfield University. Details the design of the aircraft systems and their reliability and maintainability.
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B.M. Sayed, Mohamed Fanni, Mohamed S. Raessa and Abdelfatah Mohamed
This paper aims to design and control of a novel compact transportation system called the “wearable vehicle”. The wearable vehicle allows for traversing all types of terrains…
Abstract
Purpose
This paper aims to design and control of a novel compact transportation system called the “wearable vehicle”. The wearable vehicle allows for traversing all types of terrains while transporting one's luggage in a comfortable and efficient manner.
Design/methodology/approach
The proposed design consists of a lower limb exoskeleton carrying two motorized wheels and two free wheels installed alongside its feet. This paper presents a detailed description of the system with its preliminary design and finite element analysis. Moreover, the system has been optimally designed to decrease wearable vehicle’s total weight, consequently leading to a reduction in motor size. Finally, two controllers have been designed to achieve stable operation of the wearable vehicle while walking. A PD controller with gravity compensation has been designed to ensure that the wearable vehicle tracks human motion, while a PID controller has been designed to ensure that the zero moment point is close to the center of the system’s support polygon.
Findings
Experimental tests were carried out to check the wearable vehicle concept. The obtained results prove the feasibility of the proposed wearable vehicle from the design, dynamics and control viewpoints.
Practical implications
This proposed wearable vehicle’s purpose is for traveling faster with less effort than normal walking. When a human comes across a flat open ground, the wearable vehicle can be used as a vehicle. However, when a human enters crowded traffic, an unstructured area or other obstacles like stairs, the vehicle can be switched into walking mode.
Originality/value
The wearable vehicle has seven DOFs exoskeletons, two motorized wheels, two free wheels and a foldable seat. It is used as a vehicle via its motorized and free wheels to travel fast with minimal effort. In addition, the human can switch easily into walking mode, if there is unstructured terrain to be traversed. Furthermore, an illustration of system's mechanisms and main feature parameters are presented to become acquainted with the ultimate benefits of the new system.
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This paper aims to investigate whether the Gulf Cooperation Council (GCC) is an optimum currency area in the wake of the global financial crisis and low oil prices using annual…
Abstract
Purpose
This paper aims to investigate whether the Gulf Cooperation Council (GCC) is an optimum currency area in the wake of the global financial crisis and low oil prices using annual data from 2000 to 2016.
Design/methodology/approach
It applies the European Monetary Union as a reference point and co-movement methodology on key variables such as gross domestic product, inflation, terms of trade and current account balance. The findings revealed that all countries meet the macroeconomic convergence criteria and there is greater co-movement of these variables in the GCC.
Findings
Furthermore, the degree of co-movements increases during the financial crisis and recent low oil prices, which signifies the synchronization of shocks. However, labor is less mobile in the region and current account balance co-movement is relatively weak, but with the endogeneity of a monetary union, these constraints will evaporate as the zone enters monetary unification. The paper recommends that for the GCC monetary union to happen and be sustainable, there needs to be political will. The paper also recommended for the zone to have a common identification card so that nationals can move and work freely within the GCC region.
Originality/value
The study defers from the others in the following: this paper considered shock synchronization and co-movement methodology, which has not been applied in the region to assess its feasibility as an OCA.
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Haixu Yang, Feng Zhu, Haibiao Wang, Liang Yu and Ming Shi
The purpose of this paper is to describe the structure of nonlinear dampers and the dynamic equations, and nonlinear realization principles and optimize the parameters of…
Abstract
Purpose
The purpose of this paper is to describe the structure of nonlinear dampers and the dynamic equations, and nonlinear realization principles and optimize the parameters of nonlinear dampers. Using the finite element method to analyze the seismic performance of the frame structure with shock absorber.
Design/methodology/approach
The nonlinear shock absorber was installed in a six-storey reinforced concrete frame structure to study its seismic performance. The main structure was designed according to the eight degree seismic fortification intensity, and the time history dynamic analysis was carried out by Abaqus finite element software. EL-Centro, Taft and Wenchuan seismic record were selected to analyze the seismic response of the structure under different magnitudes and different acceleration peaks.
Findings
Through the principle study and parameter analysis of the nonlinear shock absorber, combined with the finite element simulation results, the shock absorption performance and shock absorption effect of the nonlinear energy sink (NES) nonlinear shock absorber are given as follows: first, the damping of the NES shock absorber is satisfied, and the linear spring stiffness and nonlinear stiffness of the shock absorber are based on the relationship k1=kn×kl2, so that the spring design length is fixed, and the linear stiffness of the shock absorber can be obtained. The nonlinear shock absorber has the characteristics of high rigidity and frequency bandwidth, so that the frequency is infinitely close to the frequency of the main structure, and when the mass of the shock absorber satisfies between 0.056 and 1, a good shock absorption effect can be obtained, and the reinforced concrete with the shock absorber is obtained. The frame structure can effectively reduce the seismic response, increase the natural vibration period of the structure and reduce the damage loss of the structure. Second, the spacer and each additional shock absorber have a small difference in shock absorption effect. After the shock absorber parameters are accurately calculated, the number of installations does not affect the shock absorption effect of the structure. Therefore, the shock absorber is properly constructed and accurately calculated. Parameters can reduce costs.
Originality/value
New shock absorbers reduce earthquake-induced damage to buildings.
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Zhang Ming, Nie Hong, Wei Xiao‐hui, Qian Xiaomei and Zhou Enzhi
The purpose of this paper is to introduce a co‐simulation method to study the ground maneuvers of aircraft anti‐skid braking and steering.
Abstract
Purpose
The purpose of this paper is to introduce a co‐simulation method to study the ground maneuvers of aircraft anti‐skid braking and steering.
Design/methodology/approach
A virtual prototype of aircraft is established in the multibody system dynamics software MSC.ADAMS/Aircraft. The anti‐skid braking control model, which adopts the multi‐threshold PID control method with a slip‐velocity‐controlled, pressure‐bias‐modulated (PBM) system, is established in MATLAB/Simulink. EASY5 is used to establish the hydraulic system of nose wheel steering. The ADAMS model is connected to block diagrams of the anti‐skid braking control model in MATLAB/Simulink, and is also connected to the block diagrams of nose wheel steering system model in EASY5, so that the ground maneuvers of aircraft anti‐skid braking and steering are simulated separately.
Findings
Results are presented to investigate the performance of anti‐skid braking system in aircraft anti‐skid simulation. In aircraft steering simulation, the influence of two important parameters on the forces acting on the tires is discussed in detail, and the safe area to prevent aircraft sideslip is obtained.
Originality/value
This paper presents an advanced method to study the ground maneuvers of aircraft anti‐skid braking and steering, and establishes an integrated aircraft model of airframe, landing gear, steering system, and anti‐skid braking system to investigate the interaction of each subsystem via simulation.
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Javad Zahedi, Mahdi Salehi and Mahdi Moradi
The current study aims to identify and classify the financial resilience measurement indices using the intuitive fuzzy approach.
Abstract
Purpose
The current study aims to identify and classify the financial resilience measurement indices using the intuitive fuzzy approach.
Design/methodology/approach
The present study aims to identify and classify firms' indices of financial resilience measurement using the Fuzzy–Delphi combined method and the intuitive fuzzy DEMATEL technique with interval values. For the study and the literature review, 29 financial resilience indices were identified, and 12 were finalised after screening and localisation. Next, the selected indices were classified into two groups of influencing and being influenced, and the significant range of each one was determined. Finally, the executive and research suggestions were presented based on the obtained results.
Findings
The study results indicate a higher significance level of redundancy and visibility in financial resilience.
Originality/value
The present study is the pioneer study to assess, identify and classify the contributing indices to financial resilience.
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This chapter examines how hospitality and tourism researchers can use ‘expressive text’ (or writing) to express the lived quality of an experience in order to ‘show what an…
Abstract
This chapter examines how hospitality and tourism researchers can use ‘expressive text’ (or writing) to express the lived quality of an experience in order to ‘show what an experience is really like’ rather than ‘tell what it is like’. Expressive text refers to written language forms such as narrative, poetry and metaphor that can be used as tools in research to vividly represent the meaning and feeling conveyed in an experience. The expressive text-based approach to researching lived experience provides a textual link between experience and its expression. For this reason, it is especially useful when working with lived experience accounts of phenomenological and hermeneutic research.
The expressive text-based approach suggested here is still a relatively under explored arena within hospitality and tourism research. As a relatively under explored arena, the rich insightful knowledge that can be gained from understanding practitioner experience is rarely a central focus of scholarly writings about the workplace in hospitality and tourism contexts. However, in order to be fully appreciated as a discipline in its own right and to advance knowledge of the field, understanding the typical and significant attributes of hospitality and tourism work will be decidedly helpful.
One of the difficulties of working with lived experience accounts is finding a suitable research approach that helps to both retain the lived elements of the experience and ensure the rigour of the inquiry. An expressive text-based methodological framework that has a phenomenological and hermeneutic philosophical underpinning is argued to be suitable for this purpose. Therefore, the focus of this study is to discuss such a methodology and explain the reasons for its content, style and structure in researching lived experience. The approach that is proposed here consists of a five-tiered textually expressive methodology that is employed to contextualise, portray and interpret the lived experience meanings in order to understand the significance of the experience in relation to relevant discourses in hospitality and tourism studies, and to consider implications for policy and professional practice. The guiding questions of the five-tiered framework cover the following issues: (1) What is the context of the lived experience? (2) What is the lived experience of this practice like? (3) What is the meaning of this experience for the practitioner? (4) What is the significance of the experience in contributing to the advancement of knowledge within the field? (5) What are the implications for practice and professional development?
To illustrate uses of this methodology in research, the study here includes an example showing portrayals and interpretations of the typical and significant lived nature of hospitality reception work. This shows and communicates the full meaning of the episode, circumstances or situation. The chapter then concludes with some reflections on benefits as well as tensions in working within an expressive text-based phenomenological and hermeneutic framework.
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Lalitkumar Jugulkar, Shankar Singh and Suresh Sawant
The work presented in this paper is concerned with mathematical modeling and experimental validation of mono-tube shock absorber. This paper aims to create damper model to predict…
Abstract
Purpose
The work presented in this paper is concerned with mathematical modeling and experimental validation of mono-tube shock absorber. This paper aims to create damper model to predict accurately damping force, and experimental analysis is done by varying the various parameters, such as flow area in bleed(Ab), mass (M) and operating frequency(?).
Design/methodology/approach
Here, input is given in the form of sinusoidal excitation, and the output is received as a numerical data of the displacement transmissibility. These data are then processed to get the values of transmissibility and magnification factor for various frequency ratios. They are then plotted to have transmissibility and frequency response curves, as it is a generally accepted measure of how well the system is isolated from its surroundings.
Findings
It is better to have low transmissibility (larger bleed area), for lower suspension velocity, as it will reduce maximum acceleration transmitted to the sprung mass. However, for higher suspension velocity, bleed area should be low (higher transmissibility) to reduce displacement of tyre from road.
Originality/value
The development of faster vehicles and also the requirements of smoother and more comfortable rides have led to the fitment of dampers on almost on all present day vehicles. Shock absorbers have a significant influence on handling performance and riding comfort. Shock absorber plays an important role not only for comfort of the riders of the vehicle but also in the performance and life of the vehicle. However, no further reduction of vehicle vibration can be expected for using the optimum values of damping coefficient and spring stiffness for the shock absorber. Thus, it is necessary to make modification to improve the functions of shock absorber.
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THE undercarriage considered consists of a telescopic main shock absorber to the bottom end of which is pivoted a beam carrying at its extremities wheel assemblies consisting of…
Abstract
THE undercarriage considered consists of a telescopic main shock absorber to the bottom end of which is pivoted a beam carrying at its extremities wheel assemblies consisting of one, two or more wheels on a common axle. Free movement of the beam is prevented by the action of an auxiliary damper located between a point adjacent to the rear axle and a point on the beam pivot fitting. The function of the auxiliary damper is to reduce the oscillatory tendency due to unbalanced loading of the rear or front wheels and to locate the beam during flight. The damper is preferably double‐acting.