Stefan Burgard, Ortwin Farle and Romanus Dyczij-Edlinger
The goal is to derive a numerical method for computing parametric reduced-order models (PROMs) from finite-element (FE) models of microwave structures that feature geometrical…
Abstract
Purpose
The goal is to derive a numerical method for computing parametric reduced-order models (PROMs) from finite-element (FE) models of microwave structures that feature geometrical parameters.
Design/methodology/approach
First, a parameter-dependent FE mesh is constructed by a topology-preserving mesh-morphing algorithm. Then, multivariate polynomial interpolation is employed to achieve explicit geometrical parameterization of all FE matrices. Finally, a PROM based on parameter-dependent projection matrices is constructed by means of interpolation and state transformation techniques.
Findings
The resulting PROMs are of low dimension and fast to evaluate. Moreover, the method features high rates of convergence, and the number of FE solutions required for constructing the PROM is small. The accuracy of the PROM is only limited by that of the underlying FE model and can be controlled by varying the PROM dimension.
Research limitations/implications
Since the method uses topology-preserving mesh-morphing algorithms to instantiate FE models at a number of interpolation points in geometrical parameter space, there are limitations to the amount of deformation that can be handled.
Practical implications
PROM evaluations are computationally cheap. In many cases they can be evaluated hundreds or even thousands of times per second. Therefore, PROMs are very well-suited for parametric studies or numerical optimization.
Originality/value
The presented methodology employs a new way of constructing parameter-dependent interpolation matrices, based on interpolation and space transformations. The proposed methodology yields better accuracy and higher rates of convergence than previous approaches.
Details
Keywords
Daniel Klis, Stefan Burgard, Ortwin Farle and Romanus Dyczij-Edlinger
– The purpose of this paper is to determine the broadband frequency response of the impedance matrix of wireless power transfer (WPT) systems comprising litz wire coils.
Abstract
Purpose
The purpose of this paper is to determine the broadband frequency response of the impedance matrix of wireless power transfer (WPT) systems comprising litz wire coils.
Design/methodology/approach
A finite-element (FE)-based method is proposed which treats the microstructure of litz wires by an auxiliary cell problem. In the macroscopic model, litz wires are represented by a block with a homogeneous, artificial material whose properties are derived from the cell problem. As the frequency characteristics of the material closely resemble a Debye relaxation, it is possible to convert the macroscopic model to polynomial form, which enables the application of model reduction techniques of moment-matching type.
Findings
FE-based model-order reduction using litz wire homogenization provides an efficient approach to the broadband analysis of WPT systems. The error of the reduced-order model (ROM) is comparable to that of the underlying original model and can be controlled by varying the ROM dimension.
Research limitations/implications
Since the present model does not account for displacement currents, the operating frequency of the system must lie well below its first self-resonance frequency.
Practical implications
The proposed method is well-suited for the computer-aided design of WPT systems. It outperforms traditional FE analysis in computational efficiency.
Originality/value
The presented homogenization method employs a new formulation for the cell problem which combines the benefits of several existing approaches. Its incorporation into an order-reduction method enables the fast computation of broadband frequency sweeps.
Details
Keywords
The purpose of this paper is to investigate the potential effects of the so-called sharing economy on growing city tourism as well as on urban property markets.
Abstract
Purpose
The purpose of this paper is to investigate the potential effects of the so-called sharing economy on growing city tourism as well as on urban property markets.
Design/methodology/approach
Official statistical data and a geo-information system (GIS) are used on a small scale in order to identify concentration processes among overnight visitors and the potential concomitant conflicts with other interest groups.
Findings
Currently, the effects of the sharing economy on housing markets and city tourism are barely measurable and are limited to a few central locations. However, a growing demand can be discerned in housing-like accommodation concepts which can be operated via booking platforms. As there is likely to be strong future growth in this area, continuous market observation (monitoring) is urgently advised.
Research limitations/implications
Official statistics only allow an analysis of overnight guests staying with larger accommodation providers. Booking platforms for holiday homes and other temporary accommodation options have such little interest in data transparency that the overall phenomenon of city tourism can be addressed only in part.
Practical implications
Associating various data within the GIS enables municipal administrators and urban planners to identify potential sources of conflict within the property markets in good time and effectively counteract these where possible.
Social implications
Increases in property prices directly attributable to growing city tourism may lead to the displacement of less financially secure members of the established population as well as businesses.
Originality/value
The sharing economy is a relatively new research topic which will become increasingly important in future. The identification of potential sources of conflict due to tourist accommodation has therefore not yet been comprehensively carried out on a small scale.
Details
Keywords
Stefan Winkvist, Emma Rushforth and Ken Young
The purpose of this paper is to present a novel approach to the design of an autonomous Unmanned Aerial Vehicle (UAV) to aid with the internal inspection and classification of…
Abstract
Purpose
The purpose of this paper is to present a novel approach to the design of an autonomous Unmanned Aerial Vehicle (UAV) to aid with the internal inspection and classification of tall or large structures. Focusing mainly on the challenge of robustly determining the position and velocity of the UAV, in three dimensional space, using on‐board Simultaneous Localisation and Mapping (SLAM). Although capable of autonomous flight, the UAV is primarily intended for semi‐autonomous operation, where the operator instructs the UAV where to go. However, if communications with the ground station are lost, it can backtrack along its path until communications are re‐established.
Design/methodology/approach
A UAV has been designed and built using primarily commercial‐off‐the‐shelf components. Software has been developed to allow the UAV to operate autonomously, using solely the on‐board computer and sensors. It is currently undergoing extensive flight tests to determine the performance and limitations of the system as a whole.
Findings
Initial test flights have proven the presented approach and resulting real‐time SLAM algorithms to function robustly in a range of large internals. The paper also briefly discusses the approach used by similar projects and the challenges faced.
Originality/value
The proposed novel algorithms allow for on‐board, real‐time, three‐dimensional SLAM in unknown and unstructured environments on a computationally constrained UAV.
Details
Keywords
Toan Van Nguyen, Jin-Hyeon Jeong and Jaewon Jo
Because mobile manipulators are unable to climb stairs, the elevator operation is a crucial capacity to help those kinds of robot systems work in modern multifloor buildings…
Abstract
Purpose
Because mobile manipulators are unable to climb stairs, the elevator operation is a crucial capacity to help those kinds of robot systems work in modern multifloor buildings. Here, the elevator button manipulation is considered as an efficient approach to fulfill that requirement. Previously, some studies presented elevator button recognition algorithms while some others designed schemes for the button manipulation work. However, the mobile robot, the manipulator and the camera in their robot systems are asynchronous. Besides, the time-consuming calibration for the camera is inevitable, especially in changeable environments. This paper aims to present an alternative method for the elevator button manipulation to overcome mentioned shortcomings.
Design/methodology/approach
In this paper, the elevator button manipulation is conducted by using the visual-based self-driving mobile manipulator in which the autonomous mobile robot, the manipulator and the camera cooperate more efficiently. Namely, the mobile robot does not need to be located exactly in front of the elevator panel as the manipulator has the ability to adjust the initial frame of the camera based on the system kinematic synchronization. In addition, the proposed method does not require the real world coordinates of elevator buttons, but uniquely using their pixel positions. By doing this, not only is the projection from two-dimensional pixel coordinates to three-dimensional (3D) real world coordinates unnecessary, but also the calibration of the camera is not required.
Findings
The proposed method is experimentally verified by using a visual-based self-driving mobile manipulator. This robotic system is the integration of an autonomous mobile robot, a manipulator and a camera mounted on the end-effector of the manipulator.
Research limitations/implications
Because the surface of the elevator button panel is usually mirror-like, the elevator button detection is easily affected by the glare and the brightness of the environmental light condition.
Practical implications
This robot system can be used for the goods delivery or the patrol in modern multifloor buildings.
Originality/value
This paper includes three new features: simultaneously detecting and manipulating elevator buttons without the projection from pixel coordinates to 3D real world coordinates, a kinematic synchronization to help the robot system eliminate accumulated errors and a safe human-like elevator button manipulation.