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1 – 10 of 24Werner Renhart, Mario Bellina, Christian Magele and Alice Köstinger
The purpose of this paper is to achieve a very accurate localization of hidden metallic objects in human medicine applications.
Abstract
Purpose
The purpose of this paper is to achieve a very accurate localization of hidden metallic objects in human medicine applications.
Design/methodology/approach
The proposed methodology takes advantage of the eddy current effect within a metallic object. Its magnetic reaction field will be measured, e.g. with giant magnetic resistor (GMR) sensors.
Findings
A comparison of measurements and numerical results obtained by finite element computations demonstrate the reliability and positively gives a clue about the feasibility of the suggested method.
Research limitations/implications
While measuring noisy signals, the use of a lock‐in amplifier is rather expensive; especially, in applications with a high number of GMR sensors the use of channel multiplexer must be considered, which again may generate noise.
Originality/value
The paper shows how appropriate shielding of external fields in the measurement setup ensures results of satisfying quality.
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Carl H. Smith and Robert W. Schneider
The Giant MagnetoResistance (GMR) effect, discovered in France in 1988, has already been applied in magnetic sensors and has promise in other applications. The rapid acceptance of…
Abstract
The Giant MagnetoResistance (GMR) effect, discovered in France in 1988, has already been applied in magnetic sensors and has promise in other applications. The rapid acceptance of this technology is due to GMR’s unique characteristics such as high sensitivity, good temperature stability, and excellent linearity over a wide sensing range. In this article GMR materials are described as are their application in magnetic field sensors. New GMR structures utilizing spin valves and spin dependent tunneling (SDT) will offer even more potential for expanding the horizon of solid state magnetic sensing. Comparisons are made to sensors using conventional technology. Integrated GMR sensors that have signal conditioning and output electronics monolithically integrated with the sensor offer further uses of this new technology. Beyond the sensor itself, other control system functions have the potential for using the same GMR materials to make magnetic isolators and nonvolatile memories.
Aiyu Dou, Ru Bai, Huachen Zhu and Zhenghong Qian
The noise measurement on magnetoresistive (MR) sensors is generally conducted by techniques including single-channel data sampling and fast Fourier transform (FFT) analysis as…
Abstract
Purpose
The noise measurement on magnetoresistive (MR) sensors is generally conducted by techniques including single-channel data sampling and fast Fourier transform (FFT) analysis as well as two-channel cross-correlation. The single-channel method is easy to implement and is widely used in the noise measurement on MR sensors, whereas the two-channel method can only eliminate part of the system noise. This study aims to address two key issues affecting measurement accuracy: calibration of the measurement system and the elimination of system noise.
Design/methodology/approach
The system is calibrated by using a low-noise metal film resistor in that the system noise is eliminated through power spectrum subtraction. Noise measurement and analysis are conducted for both thermal noise and detectivity of magnetic tunnel junction (MTJ) sensor.
Findings
The thermal noise measurement error is less than 2%. The detectivity of the MTJ sensor reaches 27 pT/Hz1/2 at 2 kHz.
Originality/value
This study provides a more practical solution for noise measurement and system calibration on MR sensors with a bias voltage and magnetic field.
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Abstract
Various experimental groups have reported observation of both integer and fractional giant Shapiro steps in the I‐V curves of N×M arrays of superconducting‐normal metal‐superconducting (SNS) Josephson junctions. The size of these steps have been investigated both experimentally and theoretically as a function of temperature, external magnetic field, and rf current. In this report, we investigate the possibility of controlling the size of these giant Shapiro steps by an external gate voltage by considering arrays of superconductor‐semiconductor‐superconductor junctions. We show that giant Shapiro steps of different orders can be quenched over different gate voltage ranges in these arrays.
Huachen Zhu, Zhenghong Qian, Jiaofeng Zhang, Yucheng Sun, Ru Bai and Jianguo Zhu
It has been noted that the spin-valve sensor exhibits lower sensitivity with higher temperature because of the variation of GMR ratio, which could lead to the measurement error in…
Abstract
Purpose
It has been noted that the spin-valve sensor exhibits lower sensitivity with higher temperature because of the variation of GMR ratio, which could lead to the measurement error in applications where working temperature changes largely over seasons or times. This paper aims to investigate and compensate the temperature effect of the spin-valve sensor.
Design/methodology/approach
A spin-valve sensor is fabricated based on microelectronic process, and its temperature relevant properties are investigated, in which the transfer curves are acquired within a temperature range of −50°C to 125°C with a Helmholtz coil and temperature chamber.
Findings
It is found that the sensitivity of spin-valve sensor decreases with temperature linearly, where the temperature coefficient is calculated at −0.25 %/°C. The relationship between sensitivity of spin-valve sensor and temperature is well-modeled.
Originality/value
The temperature drift model of the spin-valve sensor’s sensitivity is highly correlated with tested results, which could be used to compensate the temperature influence on the sensor output. A self-compensation sensor system is proposed and built based on the expression modeled for the temperature dependence of the sensor, which exhibits a great improvement on temperature stability.
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A narration of the fascinating history of the Du Pont Company could almost fill volumes and it would be temptingly easy to utilise the journalistic cliché that here ‘space does…
Abstract
A narration of the fascinating history of the Du Pont Company could almost fill volumes and it would be temptingly easy to utilise the journalistic cliché that here ‘space does not permit’ an in‐depth documentation of the company's development and multi‐faceted diversification. However, for those unaware of the origins of this giant organisation's activities, a brief summary would take us back to 1799, in the wake of the French Revolution, when a French family set sail for America on the American Eagle, with aspirations to establish a colony in Virginia. This aim did not materialise, but in 1802 one of the sons, Eleuthère Irénée du Pont de Nemours, a former chemistry student of Lavoisier, formed his company on a piece of land along the banks of the Brandywine River near Wilmington, Delaware.
Riaz Ahmad Mufti, Rehan Zahid, Farrukh Qureshi and Jawad Aslam
The purpose of this paper is to understand the effect of engine operating conditions and lubricant friction modifier on direct acting tappet rotation. In this research work, novel…
Abstract
Purpose
The purpose of this paper is to understand the effect of engine operating conditions and lubricant friction modifier on direct acting tappet rotation. In this research work, novel method of measuring engine tappet rotation speed has been developed. The technique is so novel. It allows the measurement on real production engine with no modification to the engine tappet bore. Also, In this paper, the effect of engine operating conditions and the effectiveness of friction modifier on tappet rotation is reported.
Design/methodology/approach
For the very first time, for the purpose of measuring follower rotation in a real production engine, a 4 × 6 mm2 electronic chip called Gradiometer is mounted outside the tappet housing, allowing the monitoring of tappet rotation speed without the need to machine a hole in the tappet bore. This novel technique is adopted on Mercedes Benz OM464 engine to study the effect of engine conditions and lubricant chemistry on tappet performance.
Findings
The main outcome of this research work is the development of novel method of measuring tappet rotation. Also, during the experiments, it was revealed that although friction modifiers help in reducing friction at the cam/tappet interface, they can also adversely affect the tappet rotation speed.
Originality/value
The novel technique developed in the research work is one of the most cost effective and simple to use. Researches can adopt the technique to study the tribological performance of direct acting tappet on real production engine. Researches acknowledge the effectiveness of friction modifiers in valve train but its effect on rotation which plays a key role in the component durability has not been the focus of most of the researches mainly due to lack of effective techniques.
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This paper aims to provide details of the use of sensing skins by robots through reference to commercial products and recent research.
Abstract
Purpose
This paper aims to provide details of the use of sensing skins by robots through reference to commercial products and recent research.
Design/methodology/approach
Following an introduction, this paper first summarises the commercial status of robotic sensing skins. It then provides examples of recent safety skin research and is followed by a discussion of processing schemes applied to multiple sensor skin systems including humanoid robots. Examples of research into soft, flexible skins follow and the paper concludes with a short discussion.
Findings
The commercialisation of sensing skins has been driven by safety applications in the emerging cobot sector, and a market is emerging for skins that can be retrofitted to conventional robots. Sensing skin research is widespread and covers a multitude of sensing principles, technologies, materials and signal processing schemes. This will yield skins which could impart advanced sensory capabilities to robots and potential future uses include agile manipulation, search and rescue, personal care and advanced robotic prosthetics.
Originality/value
This paper provides details of the current role of sensing skins in robots and an insight into recent research.
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Briefly reviews previous literature by the author before presenting an original 12 step system integration protocol designed to ensure the success of companies or countries in…
Abstract
Briefly reviews previous literature by the author before presenting an original 12 step system integration protocol designed to ensure the success of companies or countries in their efforts to develop and market new products. Looks at the issues from different strategic levels such as corporate, international, military and economic. Presents 31 case studies, including the success of Japan in microchips to the failure of Xerox to sell its invention of the Alto personal computer 3 years before Apple: from the success in DNA and Superconductor research to the success of Sunbeam in inventing and marketing food processors: and from the daring invention and production of atomic energy for survival to the successes of sewing machine inventor Howe in co‐operating on patents to compete in markets. Includes 306 questions and answers in order to qualify concepts introduced.
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Jenny Wheeler has recently joined PRTM Ltd, an international operations management consultancy company offering implementation orientated support to high technology industry. PRTM…
Abstract
Jenny Wheeler has recently joined PRTM Ltd, an international operations management consultancy company offering implementation orientated support to high technology industry. PRTM Ltd has considerable experience in streamlining the manufacturing, distribution and services process. Jenny has joined to strengthen their rapidly expanding service in the area of Product Development/Time‐to‐Market, where they have currently helped clients achieve reductions in product development cycle times by more than 50%.