Juha Hagberg, Marko Pudas, Seppo Leppävuori, Ken Elsey and Alison Logan
The resolution of conventional graphical gravures is limited to about 50 to 100 microns depending on the technology used. For these gravures the depths are dependent on the widths…
Abstract
The resolution of conventional graphical gravures is limited to about 50 to 100 microns depending on the technology used. For these gravures the depths are dependent on the widths of the grooves. For electrical circuitry, the target is to achieve 25 microns line and space widths in the near future. To obtain a reasonably high sheet resistance, the printed ink height must be reasonably high. The stated requirements require further development of the whole printing process together with the associated inks. The first step was to evaluate the gravure manufacturing method, which is capable of producing gravures of sufficient accuracy and uniform depth. In this paper a new gravure printing plate manufacturing method with high accuracy is presented. Printing results made with the manufactured gravure and tailored inks are reported.
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Esa Kemppinen, Petri Mikkonen, Paul E. Collander and Seppo Leppävuori
Attenuation characteristics of microstrip transmission lines on alumina substrates up to 50GHz are discussed. The lines under test came from three different manufacturers, each of…
Abstract
Attenuation characteristics of microstrip transmission lines on alumina substrates up to 50GHz are discussed. The lines under test came from three different manufacturers, each of whom used different processes to realise the transmission lines. Two of the manufacturers used silver (Ag) paste, whereas the process of one of the manufacturers was copper (Cu) based. Each manufacturer used identical alumina substrates and identical test pattern files so that the measured attenuation properties reflected manufacturer’s capability to fabricate microstrips and the quality of the metal system used. Measurements showed that the attenuation of copper microstrips was slightly lower than that of the silver microstrips, but the difference was small. Measured attenuation (S21) of about 50Ω microstrips was approximately 0.5db/cm at 30GHz and 0.8dB/cm at 50GHz, respectively. The loss coefficient, αt, of about 0.035dB/mm at 40GHz was obtained for the Cu microstrips. Such an attenuation is reasonable for many practical applications in the microwave and millimetre wave regions.
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Mahdi Rezaei and Fariborz Saghafi
The purpose of this paper is to describe optical flow‐based navigation of a very light fixed‐wing aircraft in flight between obstacles.
Abstract
Purpose
The purpose of this paper is to describe optical flow‐based navigation of a very light fixed‐wing aircraft in flight between obstacles.
Design/methodology/approach
The optical flow information of two cameras mounted on the aircraft is used to detect the obstacle. It is assumed that the image processing has been completed and the optical flow vectors have been obtained beforehand. The optical flow is used to detect the obstacles and make a rapid turn manoeuvre for the aircraft.
Findings
It is shown that using the optical flow feedback by itself is unable to give a rapid turn to the aircraft and its rate should be employed into the control law. Six degree‐of‐freedom flight simulation showed that the proposed navigation and control strategy give satisfactory results in different flight environments like corridors with parallel and non‐parallel walls and in the L junctions. Simulations also showed that the aircraft flight velocity has little effect on collision avoidance performance.
Practical implications
This paper provides a theoretical framework to study the different parameters affect the obstacle detection and avoidance of an aircraft.
Originality/value
An analytical equation has been developed to relate the obstacle detection distance to the aircraft manoeuvrability parameters. In addition, an optical flow‐based controller also has been designed to provide rapid turn manoeuvres using the aileron control surface.
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The purpose of this paper is to provide an overview of the recent research on the interaction between flight mechanics and sensory/control systems in flies. It furthermore…
Abstract
Purpose
The purpose of this paper is to provide an overview of the recent research on the interaction between flight mechanics and sensory/control systems in flies. It furthermore, explores the application to biomimetic micro‐air vehicles (MAVs).
Design/methodology/approach
A review of recent literature on flight in flies is given first, whereafter two biomimetic case studies are discussed; the optic flow sensor developed by a French team and the micro‐mechanical flying insect project at the University of Berkeley.
Findings
The paper discusses the many areas where biological knowledge on flight in flies can be used by designers of MAVs.
Practical implications
Fully autonomous MAVs, inspired by insect flight, could be useful in a wide range of areas including search‐and‐rescue, surveillance and for military purposes.
Originality/value
The paper gives an up to date overview of dipteran flight behaviour and points to ways in which this knowledge can be applied to MAVs. The paper should thus be useful for biologists wishing to collaborate with engineers as well as for engineers and sensor designers seeking inspiration from nature.
Thin films of tellurium dioxide (TeO2) and indium oxide (In2O3) mixtures were investigated for γ‐radiation dosimetry purpose. Samples were fabricated using thermal vacuum…
Abstract
Thin films of tellurium dioxide (TeO2) and indium oxide (In2O3) mixtures were investigated for γ‐radiation dosimetry purpose. Samples were fabricated using thermal vacuum evaporation technique. The electrical properties of mixed oxides thin films [(TeO2)1−x(In2O3)x, where x=0 and 10 per cent by weight] and their changes under the influence of γ‐radiation were investigated. Samples with contacts having a planar structure showed increase in the values of current with the increase in radiation dose up to a certain dose level. Thin films in the form of pn‐junctions were fabricated with (TeO2)1−x(In2O3)x as p‐type material and sulphur as n‐type material. These pn‐junctions exhibited Zener diode behaviour. The current‐voltage characteristics for as‐deposited and γ‐irradiated samples were recorded. The level of response for all the fabricated devices was found to be highly dependent on the composition of the exposed material.