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1 – 10 of 676S. D. Farahani and Amir Hossein Rabiee
In this study, for the first time, the efficacy of control rods for full suppression of vortex-induced vibrations (VIV) and galloping of an elastically supported rigid square…
Abstract
Purpose)
In this study, for the first time, the efficacy of control rods for full suppression of vortex-induced vibrations (VIV) and galloping of an elastically supported rigid square cylinder that vibrates freely in the cross-flow direction is investigated.
Design/methodology/approach
To this aim, two small control rods are placed at constant angles of ± 45° relative to the horizontal axis and then the influence of diameter and spacing ratios on the oscillation and hydrodynamic response along with the vortex structure behind the cylinder is evaluated in the form of nine different cases in both VIV and galloping regions.
Findings
The performed simulations show that using the configuration presented in this study results in full VIV suppression for the spacing ratios G/D = 0.5, 1 and 1.5 at the diameter ratios d/D = 0.1, 0.2 and 0.3 (D: diameter of square cylinder, G: distance between rods and cylinder, d: diameter of rods). On the contrary, a perfect attenuation of galloping is only achieved at the largest diameter (d/D = 0.3) and the smallest spacing ratio (G/D = 0.5). In general, for both VIV and galloping regions, with increasing diameter ratio and decreasing spacing ratio, the effect of the control rods wake in the vortex street of square cylinder gradually increases. This trend carries on to the point where the vortex shedding is completely suppressed and only the symmetric wake of control rods is observed.
Originality/value
So far, the effect of rod control on VIV of a square cylinder and its amplitude of oscillations has not been investigated.
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Li Zhang, Jiangjun Ruan and Daochun Huang
This paper aims to establish the mathematical model and solve the complex calculation multi-field coupling problem for an electromagnetic overhead transmission line galloping…
Abstract
Purpose
This paper aims to establish the mathematical model and solve the complex calculation multi-field coupling problem for an electromagnetic overhead transmission line galloping excitation test system.
Design/methodology/approach
An electromagnetic excitation test system is introduced. To calculate the vibration response of the transmission line, a transient coupled finite element model containing electromagnetic repulsive mechanism and transmission line system was established. Considering the advantages of Newmark-ß algorithm and fourth-order Runge–Kutta algorithm, the two algorithms are combined to solve the model. Compared with the simulation results of existing commercial finite element software, the accuracy of the calculation model of electromagnetic force and wire vibration response are verified.
Findings
Comparison results show that the proposed calculation model can accurately obtain the force of electromagnetic mechanism and the vibration response of the overhead power lines, and improve the calculation efficiency. The calculation results show that vibration under electromagnetic excitation presents a double half-wave mode, and the galloping amplitude varies according to the charging voltage.
Originality/value
This paper built the transient simulation model for a galloping test system. The Newmark-ß algorithm and the fourth-order Runge–Kutta algorithm are used to solve the model. The research results are of great significance for the actual galloping test system design.
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Petr Rozmahel and Marek Litzman
This chapter elaborates on the main factors of the adverse macroeconomic development in Czechia and Europe. Currently, i.e. from 2022, Czechia mainly suffers from double-digit…
Abstract
This chapter elaborates on the main factors of the adverse macroeconomic development in Czechia and Europe. Currently, i.e. from 2022, Czechia mainly suffers from double-digit galloping inflation and GDP stagnation. The aim of this chapter is to identify and describe the influence of the main factors from the present and the more distant past on current inflation and approaching stagflation in Czechia. This chapter analyzes an unfavourable mix of demand and supply factors that leave the new banking board of the CNB facing a dilemma, that is, whether to pursue a disinflationary policy of increasing interest rates and thus push the Czech economy closer into recession or to rely on demand-driven economic growth, which will keep unemployment at a low level, but at the same time contribute to inflationary pressures. The new governor of the CNB completely changed the strategy of his predecessor and, despite strong criticism, did not raise interest rates even once. Based on the analysis of inflationary factors, this chapter tries to explain the motives for the Central Bank's new strategy in the fight against inflation, which is the systematic appreciation of the Czech koruna.
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L.R. Palmer and D.E. Orin
Legged vehicles offer several advantages over wheeled vehicles, particularly on broken terrain, but are presently too slow to be considered for many high‐speed tasks. This paper…
Abstract
Purpose
Legged vehicles offer several advantages over wheeled vehicles, particularly on broken terrain, but are presently too slow to be considered for many high‐speed tasks. This paper presents an effective 3D controller for a high‐speed quadruped trot.
Design/methodology/approach
To successfully regulate forward velocity and heading, secondary motions such as body pitch and roll must be stabilised. The complicated coupling between pitch and roll motion causes the control effort on one axis to disturb the motion and control effort of the other. Unlike the modular methods in previous research, the algorithm presented here employs a cooperative approach where pitch stability effort is directly accounted for by the roll controller.
Findings
When the secondary motions such as pitch and roll are well stabilized, forward velocity and heading can be regulated up to 3 m/s and 20°/s, respectively.
Research limitations/implications
For many quadrupeds, trotting is usually employed as the precursor to galloping, which is ultimately used at top speeds. Because these two gaits are commonly used together, we expect their control algorithms to share a number of similar components. It is then expected that understanding the quadruped trot will serve as a valuable foundation to understanding the quadruped gallop.
Originality/value
This appears to be the first reported regulation of quadruped heading while running at significant speeds.
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With organizations striving to attract Millennials into their businesses and ensure that they are entirely engaged, new approaches need to be considered. This paper aims to…
Abstract
Purpose
With organizations striving to attract Millennials into their businesses and ensure that they are entirely engaged, new approaches need to be considered. This paper aims to consider the value of equine-assisted learning (EAL) programs.
Design/methodology/approach
A literature review examined current research and use of EAL in the field of management training and development.
Findings
EAL does promote a number of so-called soft skills among employees, including communication, body language awareness, relationship building, and teamwork building.
Originality/value
EAL is an up-and-coming management training trend, the subject so far of very little research – especially so in the UK, where it has not yet had the impact it is beginning to make in the USA.
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Priyaranjan Biswal and Prases Kumar Mohanty
Legged walking robots have numerous advantages over the wheel or tracked robots due to their strong operational ability and exposure to the complex environment. This paper aims to…
Abstract
Purpose
Legged walking robots have numerous advantages over the wheel or tracked robots due to their strong operational ability and exposure to the complex environment. This paper aims to present details about the mechanical formation and a new conceptual elliptical trajectory generation discussed throughout the paper of the quadruped robot.
Design/methodology/approach
Initially, a realistic CAD model of the four-legged robot is developed in Solidwork-2019. The proposed model’s forward and inverse kinematics equations are deduced using Denavit–Hartenberg parameters. Based on geometry and kinematics, manipulability and obstacle avoidance are investigated. A method of galloping trajectory is proposed for aiming the increase of upright direction impulse, which is produced by ground reaction force at each step frequency. Furthermore, the locomotion equation of the ellipse trajectory is derived by setting transition angle polynomial of free-fall phase, stance phase and swing phase and the constraints.
Findings
Finally, a successive simulation on a 2D sagittal plane is performed to check and verify the usefulness of the proposed trajectory. Before the development of the full quadruped, a single prototype leg is generated for experimental verification of the dynamic simulations.
Originality/value
The proposed trajectory is novel in that it uses force tracking control, which is intended to improve the quadruped robot’s robustness and stability.
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Planning Review intercepted Stafford Beer after his recent luncheon address to the Montreal chapters of NASCP and PEI to extract his current views on planning and the…
Abstract
Planning Review intercepted Stafford Beer after his recent luncheon address to the Montreal chapters of NASCP and PEI to extract his current views on planning and the organization. Beer has long been concerned with the rate of change which technological achievement represents, and comments: “It is to the rate rather than to the changes themselves that we have to adapt.” In the interview that follows, he defines planning as the process of adjusting to a change in the environment. From his long inquiry into the task of organization and control in a fast‐changing environment, he concludes that the line/staff distinction is now dysfunctional. Planners and other staff personnel are making many decisions because they have the information and the decision has to be made quickly. Dr. Beer argues that these people should be given the responsibility to match the power they in fact enjoy. That power derives from information, which should not be confused with the accumulation of data. Data becomes information only at the point where it effects changes in the individual or company receiving it. Beer has long been a key figure in the fields of cybernetics, operations research, and management science. He's been a full‐time senior manager in four British companies, one a large publishing house and another United Steel, where he founded and directed for 13 years what became the largest civil operations research group. He has acted as consultant to international organizations such as the UN and the OECD and to a number of governments, including those of the United States, Britain, France, and Chile, in the sciences of management and effective organization (“the science of effective organization” is his preferred definition of cybernetics). Beer is Visiting Professor of Cybernetics at Manchester University, England, as well as Adjunct Professor of Statistics and Operations Research at the University of Pennsylvania. A conference speaker, broadcaster, and writer, Dr. Beer has published more than 150 papers and articles. Probably his best known books are Cybernetics and Management (1959), Brain of the Firm (1972), and Platform for Change (1975). In his spare time, Stafford Beer paints and writes poetry in his country home in Wales.
The Information Age during the transition from the paper era to the digital one saw the fracturing and fragmenting of the information-based specialisations. More recently…
Abstract
Purpose
The Information Age during the transition from the paper era to the digital one saw the fracturing and fragmenting of the information-based specialisations. More recently, professional norms for governance have been swept aside within new business models based on information based business applications. This paper aims to support an advance towards networked cohesion based on informatics, regenerating professionalism for the complex networked age.
Design/methodology/approach
New regulatory approaches will have to manage monistic diversity, connecting the deeper logic of continuum thinking in which information governance exists as part of a simple whole (the monistic component) with a recognition that the parts of information governance are much more complex than the whole (the expanding diversity). A continuum approach of this type involves studying things in motion as part of evolutionary processes.
Findings
The production of information is galloping ahead of its authoritative management, and this is at the heart of many of the failings of the post-truth information era. Informatics with its emphasis upon the joint operation of technologies, social processes and knowledge forming and its ability to be an umbrella term for many specialisations can be a cohering force.
Practical implications
The alignment of thought, action and ethical information governance across inter-connected practices for individuals, groups and organisations can be supported by the deeper logic and grounded experience of continuum thinking.
Originality/value
This paper will look to expand the array of sympathisers who wish to get more in touch with studying things in motion, including those trying to cope with the need to develop more adequate ways for managing nanosecond archiving processes.
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In these days of galloping inflation how much does a company need to spend on a “prestige” car? Is a car, bought with this in mind, a good investment? The accountant will usually…
Abstract
In these days of galloping inflation how much does a company need to spend on a “prestige” car? Is a car, bought with this in mind, a good investment? The accountant will usually say that it is not, arguing that you cannot quantify prestige. But the sales director knows the value (possibly even the necessity) of “making a good impression”. In this, the first of a series, we examine the type of cars that are applicable to the ‘top end’ of a company's fleet.
WHEN, PERADVENTURE, labour strife brings the steady throb of production within one's daily orbit slowly dwindling away to a strained sabbatical stillness, as though that Great…
Abstract
WHEN, PERADVENTURE, labour strife brings the steady throb of production within one's daily orbit slowly dwindling away to a strained sabbatical stillness, as though that Great Shop Steward In The Sky, for novelty, had now got the heel of a size twelve jackboot firmly planted on the jugular vein of Industry … then perforce must resolution prevail and the lubricants salesman with the crippling mortgage hurriedly find himself, revealing perhaps in his moment of self‐discovery a hitherto repressed spirit of emprise. It could be that same urge which in the Middle Ages spurred the Knight Errant to unimaginable deeds of derring‐do, leaping astride his palfry with a strange cry and galloping off to Jerusalem to slay a Saracen.