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Copies of the full Specifications are obtainable under the name ‘Deutsche Auslegeschrift’ from the Deutsches Patentamt, 1 Museumsinsel, Munich, Germany, price 1,30 DM.

The purpose of this paper is to develop a novel totally passive, wireless temperature sensor tag based on ultra high-frequency (UHF) radio frequency identification (RFID) technology. The temperature-sensing functionality is enabled by using distilled water embedded in the tag antenna substrate. The novel sensor tag is designed to provide wireless temperature readings comparable to a commercial thermocouple thermometer even in environments with high levels of interference, such as reflections. The structure of the novel sensor tag is aimed to increase its usability by minimizing user-created errors and to simplify the measurement procedure.

The sensor tag is based on a dual port sensing concept in which two ports are used to obtain sensor readings. By utilizing two ports instead of one, the effects of environmental interference, tag-reader antenna orientation and distance can be effectively minimized. Two alternative methods of acquiring the sensor reading from the operating characteristics of the two ports are presented and discussed.

Temperature measurements in practical scenarios show that by utilizing the dual port sensing concept, the developed tag produces temperature readings wirelessly which are comparable to readings from a commercial thermocouple thermometer.

The concept of dual port sensing was shown and two alternative methods on extracting sensor readings from the differences in the port operating characteristics were introduced and discussed. In this paper, the dual port sensing concept is utilized in creating a temperature sensor tag; however, the same concept can be utilized in a variety of passive wireless sensors based on UHF RFID technology. This enables a new approach in designing accurate, easy to use and easily integrable passive sensors. The dual port sensing concept is in its early stages of development; its accuracy could be improved by developing more advanced data post-processing techniques.

The accuracy of a passive dual port UHF RFID-enabled temperature sensor tag is proven to be sufficient in many applications. This indicates that other sensor types utilizing the dual port sensing concept can reach high levels of accuracy as well. Furthermore, the passive RFID-enabled sensors based on the dual port sensing concept are superior in usability versus sensor tags equipped only with a single port. Therefore, dual port sensing concept in passive UHF RFID-enabled sensor tags could make such sensors more attractive commercially and lead to truly widespread ubiquitous sensing and computing.

This paper presents a novel passive, wireless temperature sensor tag for UHF RFID systems. The sensor tag utilizes a new structure which allows tight integration of two ports and two tag antennas. The accuracy of the developed tag is confirmed throughout measurements and it is found comparable to the accuracy of commercial thermometers in practical measurement scenarios. Moreover, the paper presents a dual port sensing concept and two readout methods based on the concept which are aimed to increase the accuracy and usability of all kinds of UHF RFID-enabled sensor tags.

A guide to the various technologies available for measuring and monitoring temperature in the power generation industry. Outlines the parameters to be considered when choosing a measurement system: budgets, location, operating environment. Describes the various technologies of thermocouples, resistance thermometers, infrared thermometry and fibre‐optic temperature sensors and discusses the applications for which each is best suited.

A study has been undertaken into the use of thermal imaging techniques to determine the temperature distribution of electronic equipment. The suitability of such techniques was investigated to determine the level of confidence that could be established with regard to temperature readings obtained. The study consisted of the comparison of temperatures measured directly using fine wire thermocouples with those obtained from a thermal imaging system. Results showed that surface emissivity was a crucial factor in the determination of accurate temperatures by imaging techniques. However, by coating areas to be studied with a light deposit of aluminium chlorohydrate, a constant highly emissive surface could be obtained. This permitted temperature measurements to be made with an accuracy to within <±1 °C over the temperature range 30° to 90°C. The thermal imaging system was used to study the effect of component colour and of component density on temperature distribution. It was found, with respect to the component spacing, that the maximum component temperature was critically related to the spacing between the devices.

AS an aircraft flies through the atmosphere it is heated kinetically owing to its forward velocity. For subsonic speeds the effect is hardly measurable, at M= 1 ·5 it is definitely measurable and as there is a rapid change with speed it soon becomes necessary to include kinetic heating in the design conditions for an aircraft structure. All other conditions that are present at lower speeds have still to be retained and it becomes a matter of adding heating conditions to an already large number of conditions. The same approach must be used of preparing a design envelope on which appropriate factors have to be applied. In doing this it should be appreciated that there are two distinct effects of heating, one is the steady temperature condition associated with sustained steady flight conditions, the other is the rapid change in temperature and associated structural stresses and distortions when the aircraft changes speed or height. Considering first the steady temperature condition, it is evident that this can only arise in practice after a fairly long time at the particular flight condition to which it applies and that intermittent departures from it will not have a significant effect. The aircraft speed that has to be selected must of course be one that might reasonably be expected to be sustained occasionally for moderate periods, although perhaps not quite long enough to reach equilibrium. There is a comparable case in the normal strength requirements for gusts. The design gust has to be associated with an appropriate aircraft forward speed namely ‘Design Cruising Speed’. It is suggested that exactly the same speed be used to determine the steady temperature conditions with no further safety factor, and that all static and fatigue strength conditions be satisfied with full safety factors at this temperature condition.

The aim of this study is to develop a 3D model of decision- making grid (DMG) considering failure detection rate.

In a comparison between DMG and failure modes and effects analysis (FMEA), severity has been assumed as time to repair and occurrence as the frequency of failure. Detection rate has been added as the third dimension of DMG. Nine months data of 21 equipment of casting unit of Mobarakeh Steel Company (MSC) has been analyzed. Then, appropriate condition monitoring (CM) techniques and maintenance tactics have been suggested. While in 2D DMG, CM is used when downtime is high and frequency is low; its application has been developed for other maintenance tactics in a 3D DMG.

Findings indicate that the results obtained from the developed DMG are different from conventional grid results, and it is more capable in suggesting maintenance tactics according to the operating conditions of equipment.

In failure detection, the influence of CM techniques is different. In this paper, CM techniques have been suggested based on their maximum influence on failure detection.

In conventional DMG, failure detection rate is not included. The developed 3D DMG provides this advantage by considering a new axis of detection rate in addition to mean time to repair (MTTR) and failure frequency, and it enhances maintenance decision-making by simultaneous selection of suitable maintenance tactics and condition-monitoring techniques.