ALBERT

Notes: Purpose - Bench-top wind tunnels are used extensively by the US Air Force for calibrating anemometers. As anemometers have improved, the need for reduced uncertainties in the bench-top wind tunnels was required. A three-pronged approach was used to reduce low velocity uncertainties by a factor of 2-3.Design/methodology/approach - The reduction in velocity uncertainties was achieved by upgrading the wind tunnel instrumentation that measured the pressure and differential pressure and by improving the velocity calibration of the bench-top wind tunnel. A detailed uncertainty analysis was performed to determine how much the instrumentation needed to improve. A laser Doppler velocimetry (LDV) was used to calibrate each wind tunnel at low velocities.Findings - The uncertainty analysis indicated that the main contributors to the velocity uncertainty were the differential pressure and the pressure measurements. These two process instruments were upgraded to reduce their individual uncertainties by a factor of 2. Additionally each bench-top wind tunnel was calibrated using the LDV with special emphasis on flows from 0.15-3.0?m/s. In all, nine wind tunnels were calibrated and the upgraded systems exhibited a reduction in uncertainties in the low flow region of a factor of 2-3.Originality/value - A need to reduce velocity uncertainties in bench-top wind tunnels was a requirement for the US Air Force calibration program. Upgraded instrumentation and individual calibration with an LDV provided the needed reduction. In the low flow region of 0.15 to 3.0?m/s, uncertainties were reduced by a factor of 2-3.

Notes: Purpose - Describes the properties and uses of a new colour-change chemical for laser-printing of human and machine-readable data. Design/methodology/approach - Presents the characteristics and modes of application of the chemical, its advantages over the current techniques of inkjet printing and laser-marking, and a number of applications which show its distinctive features. Findings - This chemical gives faster throughput and better print clarity than existing laser scribing processes, and opens up new anti-counterfeiting techniques. Originality/value - Draws attention to an invention that will make an impact on factory date-coding procedures.

Notes: Purpose - To examine the possibilities for dry calibration or in situ calibration for flowmeters in the field. Design/methodology/approach - Reviews history and current situation with regard to in situ/dry calibration of flowmeters. Its acceptability for modern flowmeters is considered. Various options are considered to achieve dry calibration or in situ calibration. The possibility of action at a distance via the internet, for example, naturally follows from these developments. Findings - The paper concludes that this development is likely to be of importance to manufacturers. It will need to be addressed by certification authorities. Originality/value - The concepts will reduce the cost of calibration and the discussion should be of value to research workers, industry and government.

Notes: Purpose - Feathermoss is ubiquitous in the boreal forest and across various land-cover types of the arctic and subarctic. A variety of affordable commercial sensors for soil moisture content measurement have recently become available and are in use in such regions, often in conjunction with fire-susceptibility or ecological studies. Few come supplied with calibrations suitable or suggested for soils high in organics. Aims to test seven of these sensors for use in feathermoss, seeking calibrations between sensor output and volumetric water content. Design/methodology/approach - Measurements from seven sensors installed in live, dead and burned feathermoss samples, drying in a controlled manner, were compared to moisture content measurements. Empirical calibrations of sensor output to water content were determined. Findings - Almost all of the sensors tested were suitable for measuring the moss sample water content, and a unique calibration for each sensor for this material is presented. Differences in sensor design lead to changes in sensitivity as a function of volumetric water content, affecting the spatial averaging over the soil measurement volume. Research limitations/implications - The wide range of electromagnetic sensors available include frequency and time domain designs with variations in wave guide and sensor geometry, the location of sensor electronics and operating frequency. Practical implications - This study provides information for extending the use of electromagnetic sensors to feathermoss. Originality/value - A comparison of volumetric water content sensor mechanics and design is of general interest to researchers measuring soil water content. In particular, researchers working in wetlands, boreal forests and tundra regions will be able to apply these results.

Notes: Purpose - Reviews some of the improvements in image sensor technology that are yielding applications in the medical field. Design/methodology/approach - Discusses the characteristics and gives examples of cameras and imaging sensors used in endoscopy, microscopy, pharmaceutical label inspection and X-radiography. Reviews some innovative camera-based products for endoscopy, skin imaging and health monitoring. Findings - Improvements in camera resolution, miniaturisation and interfacing are widening the applications in medical imaging and enabling the development of some exciting new products addressing the needs of patients and medical staff. Originality/value - Identifies some suppliers of medical imaging devices and their applications.

Notes: Purpose - The paper outlines a new approach for positioning a patient on the treatment table for radiation therapy sessions. The vision approach utilizes lasers and cameras for positioning and has several advantages over the conventional methods. Design/methodology/approach - The positioning is accomplished by comparison of a set of computed tomography (CT) contours (acquired from the patient) with a set of corresponding contours acquired by a 3D vision system from the same region of the patient's body. The overall positioning error calculated by the iterative closest point algorithm is used to reorient the treatment table. Various issues related to the acquisition and generation of the 3D spatial data are discussed. Findings - Positioning is accurate and can detect small movement in the patient's position. Research limitations/implications - Testing was done on a cast of a human torso and additional testing is required on in a hospital environment to fully test the efficiency of the approach. Practical implications - The method merges data readily available from standard CT imaging systems and 3D imaging systems. Therefore, the additional hardware requirements are minimal. The system integrates well with existing hardware, software and treatment practices. Originality/value - The method introduces a new approach to patient positioning employing a combination of sensor technologies. The approach is accurate, reliable, consumes less time and most importantly prevents the use of X-rays for patient positioning.

Notes: Purpose - To provide an overview of the similarity-based modeling (SBM) technology and review its application to condition monitoring of rotating equipment using features calculated from vibration sensor signals. Design/methodology/approach - Concentrates on the practical capabilities and underlying technology of SBM. Examines the effectiveness of it as an approach to detect and diagnose faults in an electric motor-driven shaft during variable speed operating conditions. Findings - The SBM is a non-parametric pattern recognition technology developed by SmartSignal that is applied generally to multivariate condition monitoring problems. A vibration sensor is monitored by first transforming the digitized time domain sensor signal into relevant features over time. These features are monitored continuously in real time to detect any discernable differences from normality. The deviations in turn, produce fault signatures in time-feature space that aid in fault diagnosis. Originality/value - Gives information on an approach that employs a multivariate similarity-based modeling technique to characterize the expected behavior of vibration signal features which enables the detection of incipient faults in rotating machinery.

Notes: Purpose - This paper reports on a novel load cell and a novel torque transducer having stiffness and potential overload capability some ten times that of existing load cells and torque transducers based on the resistance strain gauges. Design/methodology/approach - Describes the practical capabilities and technology - the design, construction and characterisation. Findings - Both the load cell and the torque transducer use recently developed metallic triple beam resonators with thick-film lead zirconate titanate (PZT) drives and pickups. The advantages of this technology are frequency output, high overload capability, high sensitivity, high resolution, and low-cost manufacture. Both the load cell and torque transducer output large changes in frequency (〉500?Hz for relatively low changes in strain level i.e. 〈200 microstrain for the load cell and 〈400 microstrain for the torque transducer), providing high sensitivity and high overload capability. Practical implications - Load cells and torque transducers employing the new metallic resonators are expected to be far more robust than those using metallic resistance strain gauges. Originality/value - Focuses on an instrument with important features of use in many applications.

Notes: Purpose - To draw attention to some recent developments in machine vision equipment. Design/methodology/approach - Presents advances in light emitting diode (LED) lighting, cameras and software, and gives examples of new products and their capabilities. Findings - New thermal management techniques allow LED lights to take over many machine vision illumination systems. Lights and cameras can be ruggedised to withstand wash down. Standard interfacing is being adopted for machine vision cameras. Originality/value - Highlights some new products which have applications including the food industry.

Notes: Purpose - A prototype gas prover was constructed to serve as the Italian primary standard for gas flow rates in the range 0.1?ml/min to 2?l/min. The new prover is used to calibrate high-quality industrial standards, as well as the MFCs used in microelectronic fabrications and preparation of reference gas mixtures.Design/methodology/approach - The prover measures gas volume transfers caused by displacements of a 120?mm dia. motor-operated piston, which is introduced into a temperature-controlled chamber containing up to 3?l of the required working gas at near ambient conditions. Gas delivery is made at constant rate, whereas possibly variable incoming flows are measured at constant pressure. Displacements of the piston are measured by an optical interferometer.Findings - The analysis shows that standard uncertainty ranges between 0.013 and 0.03 percent. Owing to the very accurate control and measurement of both pressures and temperatures, these figures refer equally to volume and mass flowrate. Experimental comparisons with similar national standards at LNE-France and NIST-USA confirmed the consistency of measurement results in the three Nations.Research limitations/implications - The gas prover should be used with inert gases only.Practical implications - The national industrial gas standards and the best flow transducers can now be calibrated accurately down to unprecedented flowrate values.Originality/value - The need for measurement of extremely low gas flows is quite recent, therefore possibly less than ten primary national standards are available today worldwide. Several completely different principles and designs have been developed; description of design and performance of each instrument is important to assess their respective merits. The described apparatus is innovative as regards measurement range, accuracy and control techniques.

Notes: Purpose - To discuss the application of direct part marking identification (DPMI) using 2D matrix codes, the use of which is increasing in industries as diverse as automotive and medical instruments.Design/methodology/approach - The benefits of 2D codes are explained, emphasising that they have sufficient storage capacity to provide data for tracking a part during its manufacture and through the supply chain and allow traceability throughout its lifetime. It describes the operation of Cognex, one of the leading manufacturers of ID products and also the world's largest supplier of machine vision systems is Cognex. It explains that initially the electronics industry exploited Cognex' code reading technology and an application at a German board manufacturer is described. Another system, at a diesel engine injector manufacturer in France, has 42 Cognex systems reading 2D codes and guiding robots in assembly. Also described is a new range of Cognex hand-held and fixed-mount 1D and 2D code readers "loaded" with software that allows reading in difficult conditions and with degraded or partially obscured codes.Findings - The DPMI market has expanded into industries other than automotive, which has prompted Cognex to establish a new division of ID products.Originality/value - The paper emphasises the importance of 2D codes in product traceability and indicates how vision technology is being utilised to read these codes even under difficult conditions.

Notes: Purpose - The need for an instrumented grinding system that addresses the requirements of ductile regime machining of brittle materials is implemented. The static and dynamic stiffness of the structural loop of the grinding system meets or exceeds those of previous researchers. An instrumented spindle is introduced which features capacitance gages embedded in the stator of an air bearing spindle. Design/methodology/approach - The instrumented spindle is demonstrated to provide valuable force feedback for fine grinding and is capable of resolving intra-revolution force components. Tests are performed to demonstrate the use of the instrumented spindle for ductile grinding of brittle materials with superabrasive wheels. Findings - The results of the test show that the instrumented spindle is capable of determining intra-revolution force components for square alumina-titanium carbide wafers. Originality/value - Outlines some important work developing and building instrumented spindles to aid the precision grinding industry.

Notes: Purpose - This article provides details of recent research in France and Germany which has extended the operational range of the laser-induced breakdown spectroscopy (LIBS) technique through the use of a transportable terawatt laser, the "Teramobile". Design/methodology/approach - The high power of the Teramobile's laser generates self-guided filaments of light which overcome the diffraction limit that restricts the range of conventional pulsed laser sources in air to around 100?m. The system can deliver laser intensities of around 1013?W/cm2 to locations at a distance of several kilometer without focusing. It has been used in a variant of the LIBS technique termed remote filament-induced breakdown spectroscopy (R-FIBS). Findings - Experiments have shown that the R-FIBS technique can analyse metal samples for elemental composition at a range of up to 180?m. Further work offers prospects to extend the range to as much as 1?km. Originality/value - This research illustrates that a transportable terawatt laser can be used as the source in the new R-FIBS technique, suggesting many remote sensing analytical applications such as environmental monitoring, detecting chemical and biological warfare agents, monitoring the composition of molten metals and identifying radioactive waste.

Notes: Purpose - This paper discusses the size and structure of the global biosensor market which is presently dominated by medical applications. Design/methodology/approach - It considers a number of recent developments based on nanotechnology. Findings - Identifies homeland security as an emerging area offering significant prospects for technological innovation and market growth. Originality/value - Of interest to those concerned with technology developments.

Notes: Purpose - The sensitivity of orifice plate metering to poorly conditioned and swirling flows are subjects of concerns to flow meter users and manufacturers. The distortions caused by pipe fittings and pipe installations upstream of the orifice plate are major sources of this type of non-standard flows. These distortions will alter the accuracy of metering up to an unacceptable degree.Design/methodology/approach - The design of orifice plate meters that are independent of the initial flow conditions of the upstream is a major object of flow metering. Either using a long straight pipe or a flow conditioner upstream of an orifice plate usually achieves this goal. The effect of cone swirler flow conditioner for both standard and non-standard flow conditions has been carried out in the experimental rig. The measuring of mass flow rate under different conditions and different Reynolds numbers were used to establish a change in discharge coefficient relative to a standard one.Findings - The experimental results using the cone swirler flow conditioner showed that the combination of an orifice plate and cone swirler flow conditioner is broadly insensitive to upstream disturbances. The results clearly show that this flow conditioner can attenuate the effect of both swirling and asymmetric flows on metering to an acceptable level.Originality/value - Previous work on the orifice plate has shown that the concept has promise. The results of using a combination of a cone swirler and orifice plate for non-standard flow conditions including swirling flow and asymmetric flow show this package can preserve the accuracy of metering up to the level required in the standards, providing that a new discharge coefficient is used for the combined swirler and orifice plate.

Notes: Purpose - Owing to the technology growth, especially in Microsystems technology and Nanotechnology, new products will provide new ways to sense variables that are crucial for product improvement and system reliability. A big concern of the scientific community is the measurement of low level flow measurements, especially for the biomedical and/or systems on a chip approaches.Design/methodology/approach - A new flow meter concept design consists of a surface micromachined sensor having an optical high reflective mirror made of gold, which is attached to unique cantilever designs that bend due to the drag force of mass flow. The bending of the cantilevers produces the mirror to approach/depart from an optical fiber end-tip. The reflective light to fiber is modulated using a Fabry-Perot interferometry technique to determine the mirror separation to the fiber, which corresponds to the mass flow.Findings - The new concept design shows a big potential approach to measure low flow measurements for air, gas and liquids of low viscosity. The results of this concept, through finite element analysis, show that the material used to build the sensor, makes them excellent candidates for fabrication. The stresses of the materials and allowable (readable) bending are among the tolerances of such materials/construction-design. The sensor is not affected by electromagnetic interference and does not require electrical currents to sense, i.e. it is perfectly suited for biomedical and low mass-flow sensing such as lab-on-chip applications.Originality/value - Among all approaches to sense low flow measurements, most of them need either "big" turbine approaches (dimensions over 1?cm diameter), or the need of an electrical approach needed in the end measurement sensor. This work proposes a non-electrical approach.

Notes: Purpose - To present two non-contact methods of measuring vibrations and impact events. Design/methodology/approach - The paper concentrates on the practical capabilities and underlying technology of commercial high-speed CMOS cameras and laser Doppler vibrometers. Findings - The instruments are used to analyse modes of failure and to test quality in a very wide range of products. They are also used to develop safety and protective devices, and to study natural phenomena. Originality/value - A practical guide to the tools available, with some example applications of interest to production engineers.

Notes: Purpose - This paper describes a recent collaborative project involving the development of a multiplexed fibre Bragg grating (FBG) sensor system for structural integrity monitoring. Design/methodology/approach - The system is described and field trials on both conventional and novel composite bridges are discussed. A FBG sensor-based structural monitoring system was developed, based on a fluorescent fibre as the optical source. It used a tuneable, fibre-coupled, Fabry-Perot filter, actuated by piezoelectric transducers and operated over the bandwidth of the source at up to 250 scans/second. Light from the source was filtered and reflected back from the Bragg gratings, through optical couplers, to eight photodiode detectors. These detected the resulting time-domain spectra of the sensors in each of the serially connected sensor arrays. The system was tested at City University and then subjected to trials on the Mjosund road bridge in Norway and on West Mill bridge in Oxfordshire, UK, which is the first bridge to be fabricated from a new type of composite material. Findings - During the Norwegian trials the system was arranged with four or five FBG sensors per channel giving a total of 32 measurement points with eight parallel channels. Twelve conventional foil strain gauges and a number of thermocouples were also installed. Different static and dynamic loads were applied over a period of 18 months and the results showed that the thermally compensated strain data obtained optically matched those from the resistive gauges to within 〈5?µ?. During the construction stage of the Oxfordshire bridge, sections of the decking and longitudinal composite support beams were instrumented with 40 FBG sensors with temperature compensation, placed at pre-selected sites of maximum strain. These exhibited a resolution of ±5?µ? and an operating range of over ±2,000?µ?. Originality/value - This research has shown that multiplexed, multi-point FBG sensor systems can accurately and reliably monitor both static and dynamic strains in large structures over a range of temperatures and for extended periods of time.

Notes: Purpose - To describe the development of and experience with a system that tracks the position of knocks and taps atop a large sheet of glass for use as an inexpensive retrofit that can make large windows into interactive interfaces. Design/methodology/approach - The structural-acoustic wavefront coming from the impact is simultaneously recorded by four contact piezoelectric pickups mounted near the sheet's corners. A digital signal processor extracts relevant characteristics from these signals, such as amplitudes, frequency components, and differential timings, which are used to estimate the location of the hit and derive other parameters, including a degree of confidence in the position accuracy, the strike intensity and the nature of each hit (e.g. knuckle knock, metal tap, or fist bang - our system responds to any kind of impact). A set of heuristically-guided rules are employed to compare the waveforms recorded by different sensors and determine the differential timing. Findings - Across sensitive areas ranging up to 2×2?m, we have obtained position resolutions of s=2.5?cm for 1/4?in. tempered glass and s=3-4?cm for 1?cm thick shatterproof glass. Our system delivers 65?ms latency, hence is essentially real time. The system has been installed in several public settings, and has proven to be very robust. Research limitations/implications - Suggestions are given for doing everything in software and not using the DSP. Analytical compensation of the dispersion would probably yield better precision but require more computation time. Practical implications - As this system requires only simple hardware, it needs no special adaptation of the glass pane, and allows all tracking transducers to be mounted on the inner surface, hence it is quite easy and inexpensive to deploy as a retrofit to existing windows. This opens many applications, such as an interactive storefront, with content controlled by knocks on the display window, an interactive museum display case, or a vending machine where one can select by tapping directly above the desired item. Originality/value - As large displays become less costly and more common, systems like these can make them interactive. This paper details our approach.

Notes: Purpose - To describe a new substrate for use in surface enhanced Raman spectroscopy (SERS). Design/methodology/approach - Novel SERS substrates have been produced by the nanometre-scale patterning of gold surfaces on silicon. This forms photonic crystals which tightly control the physics of the surface enhanced Raman amplification process, producing consistent SERS signals. Findings - It has been shown that these substrates can increase significantly the sensitivity and reproducibility of SERS. Originality/value - These substrates will allow SERS to be used in critical applications requiring high sensitivity detection of chemical compounds such as security, forensics, healthcare and environmental monitoring.

Notes: Purpose - To describe the function and use of the GreenSeeker™ active remote sensor used to detect crop nitrogen status. Design/methodology/approach - In this paper, the GreenSeeker active remote sensor and its use in irrigated maize production systems will be described. A brief discussion of the science of using remote sensing for studying plants is presented. Additionally, a summary of observations collected from field trials is presented. Findings - The GreenSeeker active sensor has tremendous potential for accurately characterizing crop variability for site-specific N rate determinations in the Western Great Plains region of the United States. Originality/value - This paper discusses the GreenSeeker active sensor for detecting crop variability. Data from the GreenSeeker can be used to make site-specific nitrogen fertilizer applications which may lead to improved nitrogen use efficiency.

Notes: Purpose - Examines some of the recent technical developments that are leading to a wider use of powerful methods in medical microscopy. Design/methodology/approach - Reviews some of the microscopic techniques relevant to medicine, then looks at hardware developments in microscopes, filters and cameras. Findings - Highly sophisticated techniques such as time-resolved fluorescence measurements are now incorporated in turnkey instruments, using picosecond diode lasers for accurate measurement of fluorescent lifetimes. Advances in optical fibre coating technology in the telecoms field have led to improved filters for fluorescence microscopy, and imaging allows the detection of non-visible wavelengths and very low light levels. Many microscopes are modular, so that users can upgrade to further capabilities at will. Automatic medical diagnosis software is coming onto the market. Originality/value - Highlights the hardware and software developments that are enabling powerful microscopic methodologies to enter into general use.

Notes: Purpose - To describe a new high sensitivity, nanotechnology-based technique for detecting DNA and disease-related proteins. Design/methodology/approach - Gold nanoparticles and magnetic microparticles are bound to single-stranded DNA molecules that are complementary to segments of the target DNA. The nanoparticles also link to hundreds of strands of "barcode" DNA and in the presence of the target, each molecule binds to a gold nanoparticle and a magnetic microparticle. Applying a magnetic field enables the separation of the target molecules and their attachments. The DNA is removed from the molecules and detected by a chip-based DNA procedure. As each nanoparticle links to a large number of strands of DNA, the method amplifies the signal from each target molecule. The technique can also detect proteins by replacing the complimentary DNA with antibodies. Findings - This research shows that this technique can detect very low concentrations of DNA and proteins. Ten copies of anthrax DNA were detected in 30?µl of solution, a sensitivity comparable to polymerase chain reaction, and 18-20 PSA molecules were detected in a 10?µl sample, a level of detection that is six orders of magnitude more sensitive than conventional assays. Recent research has also shown that the assay can detect ADDLs, which are biomarkers for Alzheimer's disease. The technologies are now being commercialised by Nanosphere, Inc. Originality/value - These developments offer prospects in a wide range of clinical applications such as the rapid and simple diagnosis of a variety of diseases and single nucleotide polymorphisms tests for the detection of hypercoagulation disorders. Other potential applications include homeland security and environmental monitoring.

Notes: Purpose - Aims to report on a new trend of research and development in the wireless capsule endoscope. Design/methodology/approach - Presents a conceptual design of a wireless capsule endoscope having new features like navigation control, self-propulsion, higher rate image transmission, acquisition of samples, application of medications and so forth. Findings - The basic principle has been verified by experiments. Seems promising. Research limitations/implications - Yet to need a lot of effort for commercialization. Practical implications - If successful, it will provide another way of least invasive medical treatment that must reduce pain of patients drastically. Originality/value - Taking advantage of the state-of-the-art micro-technology it suggests a further step beyond the current wireless capsule endoscope.

Notes: Purpose - Computer tomography (CT) for 3D reconstruction entails a huge number of coplanar fan-beam projections for each of a large number of 2D slice images, and excessive radiation intensities and dosages. For some applications its rate of throughput is also inadequate. A technique for overcoming these limitations is outlined.Design methodology/approach - A novel method to reconstruct 3D surface models of objects is presented, using, typically, ten, 2D projective images. These images are generated by relative motion between this set of objects and a set of ten fanbeam X-ray sources and sensors, with their viewing axes suitably distributed in 2D angular space.Findings - The method entails a radiation dosage several orders of magnitude lower than CT, and requires far less computational power. Experimental results are given to illustrate the capability of the techniquePractical implications - The substantially lower cost of the method and, more particularly, its dramatically lower irradiation make it relevant to many applications precluded by current techniquesOriginality/value - The method can be used in many applications such as aircraft hold-luggage screening, 3D industrial modelling and measurement, and it should also have important applications to medical diagnosis and surgery.

Notes: Purpose - A review of selected vision exhibits and innovations at a new biennial international trade fair in Germany, which essentially replaces the traditional substantial vision presence at the annual Hanover Industry Fair.Design/methodology/approach - Five companies are profiled; four (ISRA Vision, Vitronic, AKATech, and INOS Automation) with innovative products and one (Stemmer Imaging) with a highly European approach to marketing.Findings - One claimed innovation was foreshadowed 20 years ago, but this time it works! Many successful applications of machine vision are now in sectors outside the traditional manufacturing field. These include logistics and aspects of traffic management. The ability to measure moving items accurately was a major advance.Originality/value - This will alert vision practitioners, and researchers intent on commercialisation, who did not get to Munich to the latest developments and opportunities for commercial exploitation of automated imaging technology. It will help them to judge whether a visit to the next event in May 2006 will be justified.

Notes: Purpose - To provide corporate and technical details of the US-based Endevco Corporation. This company is a leading manufacturer of sensors and systems for measuring vibration, shock and other physical variables.Design/methodology/approach - This profile considers the Endevco company structure, technology, products, markets and applications, including historical achievements and recent developments.Findings - This paper discusses the company's use of piezoelectric ceramic and microengineered silicon technologies in a range of high performance sensors for measuring shock, acceleration, vibration and pressure.Originality/value - This provides an insight into the Endevco company structure, products, technologies and markets.

Notes: Purpose - To describe a new laser-based, optical airspeed sensor development project. Dubbed laser air speed sensor instrument (LASSI), the sensor aims to overcome certain operational limitations of existing devices used on aircraft.Design/methodology/approach - The LASSI system is being developed by a consortium of UK organisations. It relies on Doppler wavelength shifting and involves firing short duration laser pulses from the aircraft into the atmosphere and measuring the velocity-induced Doppler shift in the reflected (Rayleigh scattered) signal. The source is a diode-pumped Nd:YAG laser operating at UV wavelengths.Findings - The project has reached the stage where a prototype system test bed is being assembled. Preliminary findings suggest that the system will offer a number of operational and economic benefits over existing devices, notably Pitot tubes.Originality/value - This new optical system is expected to improve helicopter safety during low-speed activities, yield fuel savings on long-haul passenger aircraft through a reduction in drag and also reduce the radar cross-section of military aircraft.

Notes: Purpose - To establish an accurate and sensitive method to characterize the moisture content of a particular environment. Design/methodology/approach - This paper proposes a relatively simple humidity sensor design consisting of electrodes on a suitable substrate coated with a polyimide material. The changes in relative humidity are denoted by a corresponding change in the polyimide material's electrical resistance profile. The design proposed in this work can be microfabricated and integrated with electronic circuitry. This sensor can be fabricated on alumina or silicon substrates. The electrode material can be made up of nickel, gold or aluminum and the thickness of the electrodes ranges typically between 0.2 and 0.3?µm. The sensor consists of an active sensing layer on top of a set of electrodes. The design of the electrodes can be configured for both resistive and capacitive sensing. Findings - The polyimide material's ohmic resistance changes significantly with humidity variations. Changes in resistance as large as 4-6 orders of magnitude are attainable over the entire operational humidity range. Research limitations/implications - As the sensitivity varies non-linearly with the humidity, the measurement has to be carried out over a very wide range in order to calibrate the sensor. The sensitivity and output range of the sensor can be easily controlled by changing the electrode spacing or geometry. Practical implications - The control of humidity is important in many applications ranging from bio-medical to space exploration. Originality/value - A simple, easy to fabricate and measure, and low cost resistive-type humidity sensor was developed. The realized sensor is suitable for integrating with microfabrication. Hence, multiple sensors of varying sensitivities and output ranges could be integrated on the same chip. Over the last few years, newly emerging micro-electro-mechanical-systems technology and micro-fabrication techniques have gained popularity and importance in the miniaturization of a variety of sensors and actuators.

Notes: Purpose - To describe a new optical fibre Bragg grating (FBG) sensor system, based on a novel time division multiplexing technique, which is being commercialised by UK start-up Insensys. This new technique allows sensor costs to be reduced dramatically and also yields operational benefits.Design/methodology/approach - The system uses time division multiplexing (TDM) rather than wavelength division multiplexing (WDM) to interrogate the sensors. All the FBG sensors are written at the same wavelength and the interrogation unit receives a number of pulses from each grating. These pulses arrive at a time determined by the grating distance from the interrogator and one grating sensor can be distinguished from another by analysing the pulse arrival times. As a result, there is no need for a tuneable laser or filter and a single mask can be used to write all of the gratings, thus reducing both manufacturing and component costs.Findings - This design has led to lower costs and allows up to 100 strain or temperature sensors to be incorporated into a single channel system, rather than around 4, which is the norm for conventional WDM systems. The company is now in production and has orders for systems to monitor the strain in wind turbine blades, to measure temperature profiles in oil wells and to monitor the stress in composite structures.Originality/value - This TDM-based design allows FBG sensor systems to measure far more points per fibre than is possible with conventional WDM system, combined with lower system costs. Applications are being found in the marine, aerospace, offshore and power generation industries.

Notes: Purpose - To provide detailed information about the novel universal frequency-to-digital converter UFDC-1, which can help engineers and researchers to design new digital sensors and transducers, as well as smart sensors and sensor systems. Design/methodology/approach - The high performance of the UFDC-1 is achieved by using four novel measuring methods for frequency-time parameters. All existing integrated frequency-to-digital converters and frequency (time) output sensors have been reviewed and current design requirements for the UFDC-1 have been formulated. Findings - The UFDC-1 enables the transition from traditional analog (voltage and current) sensors output to frequency-time output. This yields a lot of benefits due to the properties of frequency as informative parameter. No output standardization is necessary, as opposed to the case of analog output sensors. Users can now work with the UFDC-1, the same as with traditional ADCs. Sensor manufacturers can simply integrate the UFDC-1 in microsystems and digital output sensors in order to produce serial output or bus capability. Practical implications - The UFDC-1 has many applications: obtaining a digital output from any frequency, period, duty-cycle, time interval, phase-shift, pulse number output sensors, up to one chip digital sensors design and smart (self-adaptive) sensors, thanks to its programmable relative error and non-redundant conversion time. The UFDC-1 can work with any existing frequency-time domain sensor to produce a digital output or create multiparametric smart sensors and systems. Originality/value - This paper fulfils an identified information need and offers practical help to engineers and researchers in designing new digital sensors and transducers, as well as smart sensors and systems using a minimum of hardware.

Notes: Purpose - The paper draws together a range of somewhat unusual machine vision applications, with an integrating overview. Design/methodology/approach - The National Centre for Engineering in Agriculture is amassing a portfolio of projects involving machine vision. These include identification of animal species, visual counting of macadamia nuts, analysis of animal behaviour and a number of quality control functions. DirectX tools have been developed and are applicable across a wide range of applications, while theory is extended in several ways. Findings - Most of the projects are still in progress, but results are reported on the degree of success of a range of methods. Strategies and algorithms are discussed. Research limitations/implications - Vision-based solutions are applied to a diversity of tasks. There will be a continuing stream of such problems with abundant opportunities for research. Practical implications - The projects are in essence practical, although they have inspired new methodologies. They are conducted in close collaboration with the industries involved and will be deemed to have failed if the outcome is not put to commercial use. Originality/value - The paper draws together a portfolio of projects, allowing an analysis to be made of the features that unite and differentiate them. It will be of interest to both researchers and those with instrumentation problems.

Notes: Purpose - Aims to design a heterogeneous embedded system with CPLD and microcontroller as co-processors sharing a memory module. Design/methodology/approach - The system receives external analog input signal, which is applied to the PIC 16F73 microcontroller. Upon converting the data in to digital format using the on-chip ADC, the PIC stores the digitized version in the SRAM (HCM 6264) chip. SRAM HCM 6264 has been used as a shared memory model, of which both the PIC and CPLD can access all the locations. Once the PIC passes controls to the CPLD, the further processing is carried out by the CPLD without any intervention of the PIC. This is a true example of co-processing of the architecturally diversified computing modules from completely different vendors with totally different programming suits. Findings - The board has been tested with IC temperature sensors and also found to be useful for sensor array applications involving three types of processing viz. analog (through instrumentation amplifier), real-time digital (through microcontroller) and customized reconfigurable digital (with the CPLD). Practical implications - The system has several potential applications in avionics, military and robotic embedded systems, which have inherent real-time constraints that need to be supported by the underlying hardware and driver programs. Originality/value - Discusses the rare and unique combination of diversified processing core to build an embedded system.

Notes: Purpose - To review the manufacture of specialty optical fibres used in sensors.Design/methodology/approach - Describes speciality optical fibres that use fibre Bragg gratings and time division multiplexing. Applications include structural monitoring in wind turbines, yacht masts and civil engineering structures.Findings - The oil and gas industry has used these types of sensors because of their cost efficiency and safety. As the sensors have no electrical connections they generate no heat and use only low power light, which makes them ideal for hazardous areas. It also enables reliable and highly-stable, long term monitoring of critical production equipment.Originality/value - Provides a source of information on speciality optical fibre sensors.

Notes: Purpose - There are various temperature measuring systems presented in the literature and on the market today. Over the past number of years a range of luminescent-based optical fibre sensors have been reported and developed which include fluorescence and optical scattering. These temperature sensors incorporate materials that emit wavelength shifted light when excited by an optical source. The majority of commercially available systems are based on fluorescent properties.Design/methodology/approach - Many published journal articles and conference papers were investigated and existing temperature sensors in the market were examined.Findings - In optical thermometry, the light is used to carry temperature information. In many cases optical fibres are used to transmit and receive this light. Optical fibres are immune to electromagnetic interference and are small in size, which allows them to make very localized measurements. A temperature sensitive material forms a sensor and the subsequent optical data are transmitted via optical fibres to electronic detection systems. Two keys areas were investigated namely fluorescence based temperature sensors and temperature sensors involving optical scattering.Originality/value - An overview of optical fibre temperature sensors based on luminescence is presented. This review provides a summary of optical temperature sensors, old and new which exist in today's world of sensing.

Notes: Purpose - To present a new generation of liquid flow sensors that is capable of meeting the requirements as imposed by the life science, analysis, biotech and other markets.Design/methodology/approach - A description of the design and development of low flow rate measuring system and typical applications.Findings - The system described uses tubes made of silica, stainless steel or PEEK, and either constant power or constant temperature methods in conjunction with a heater and temperature sensor. The tested instruments were capable of measuring flow ranges between 25-500?nl/min (smallest flow range) and 100-2000?µl/min (largest flow range) water, with operating pressures up to 100 bar (up to 400 bar for flow meters with flow ranges below 100?µl/min).Originality/value - Presents information on a new generation of liquid flow sensors.

Notes: Purpose - To describe a new technique, developed in Korea, which extends the operational length of fibre Bragg grating strain and temperature sensors to approximately 50?km. It is based on distributed Raman amplification.Design/methodology/approach - The system uses a single pump source to achieve distributed Raman amplification in the transmission optical fibre and does not employ an additional broadband light source, as the residual pump power after the transmission fibre is recycled to generate broadband amplified spontaneous emission in an erbium-doped fibre.Findings - The temperature and strain response of the system was tested by measuring changes in reflection from the sensor which were captured on an optical spectrum analyser, located at the end of a 50?km length of fibre. The thermal sensitivity was found to be 8.2?pm/°C over the range 30-100°C and a strain sensitivity of 1.1?pm/µ? was exhibited between 0 and 1,700?µ?. The measurement resolutions of the system for temperature and strain were estimated at 0.7°C and 8.64?µ?, respectively. The signal-to-noise ratio was approximately 11?dB.Originality/value - This work has shown that the use of distributed Raman amplification can extend the operational length of fibre Bragg grating sensors from around 25?km to at least 50?km, whilst achieving good strain and temperature sensitivities.

Notes: Purpose - In model-based recognition the 3D models of objects are stored in a model library during an offline phase. During the online recognition phase, a view of the scene is matched with the model library to identify the location and pose of certain library objects in the scene. Aims to focus on the process of 3D modeling and model-based recognition. Design/methodology/approach - This paper discusses the process of 3D modeling and model-based recognition along with their potential applications in industry with a particular emphasis on robot grasp analysis. The paper also emphasises the main challenges in these areas and give a brief literature review. Findings - In order to develop an automatic 3D model-based object recognition system it is necessary to automate the process of 3D modeling and recognition. The challenge in automating the 3D modeling process is to develop an automatic correspondence technique. The core of recognition is the representation scheme. Recognition is an online process. Therefore, representation and matching must be very fast in order to facilitate real time recognition. Practical implications - There are numerous applications of 3D modeling in a variety of areas ranging from the entertainment industry to industrial automation. Some of its applications include computer graphics, virtual reality, medical imaging, reverse engineering, and 3D terrain construction. Originality/value - Provides information on 3D modeling which constitutes an important part of computer vision or robot vision.

Notes: Purpose - This paper describes the discovery of waveguides capable of transmitting electromagnetic radiation at terahertz (THz) frequencies. Until now this has not been possible, despite extensive research. Design/methodology/approach - The discovery was made by a research group at Rice University whilst working on apertureless, near-field THz microscopy. By chance, the group found that bare metal wires are capable of transmitting THz radiation to and from remote samples with virtually no dispersion and little attenuation. Findings - This discovery allows THz waves to be taken directly to and from the source and detector and eliminates the need for objects to be positioned directly in the THz beam. It also overcomes problems associated with shock and vibration. Subsequently, the group used this phenomenon to develop the world's first prototype THz-frequency endoscope, which was used to examine a glass flask. Originality/value - The availability of THz waveguides will allow many new applications to be realised. A major use is expected to be security, where systems could be used for checking passengers and baggage at airports, etc. for concealed weapons, drugs and explosives. Uses in product quality control and healthcare are also anticipated.

Notes: Purpose - A novel sensor system is described that can replace the need to use a touch screen, mouse or keyboard for use with either a thin film transistor (TFT) or cathode ray tube (CRT) screen. Design/methodology/approach - A tri-colour photodiode in a colour sensor pen (CSP) is used as an input to depict where a user is pointing by detecting a dynamic kaleidoscope of colours flashed onto the screen. The most easily detected colours are placed around the predicted position of the sensor. The output from the sensor is filtered and transmitted to a computer where colour is translated into a corresponding co-ordinate. An artificial neural network (ANN) ensures that optimum colours are placed closest to the sensor by predicting future pointer position. Findings - The CSP successfully provided an input that depicted where a user was pointing. Sensors tested were not able to differentiate more than 28 colours on a TFT screen but an ANN system made them more accurate. Hue and Saturation were successfully used to model colour in a two-dimensional colour grid as they were unaffected by brightness. The sensor output was successfully converted into a co-ordinate and used to move a cursor. The kaleidoscope of colours was dynamic as it changed size and colour to increase accuracy. The ANN successfully predicted future positions to assist the sensor in making optimum colour detections. The best predictions of future positions were obtained with four and eight hidden neurons and there did not appear to be any significant advantage in training with more than 2,000?epochs. The system has performed satisfactorily for various inputs. Research limitations/implications - The novel light pen works on TFT and CRT screens. Problems included the time that colours needed to be left on a screen to be detected and the limited number of colours that could reliably be detected. These were overcome by using a dynamic kaleidoscope of colours to improve colour detection and an ANN to predict future pointer positions, based on previous locations. This prediction was used to place optimum colours closest to the sensor in order to increase accuracy. Further testing is taking place to confirm that the sensor can be used at any angle. Practical implications - The novel light pen type peripheral and intelligent colour sensing system can replace the need to use a touch screen, mouse or keyboard. Originality/value - The new intelligent colour sensing system works on either a TFT or CRT screen. The use of the colour translation and sensor and the ANN to predict future pointer position are all novel.

Notes: Purpose - To review the use of near-infrared (NIR) spectroscopy in the process control of foodstuffs. Design/methodology/approach - Presents two spectroscopy products used in the production environment: a single-board system aimed at OEMs, and a complete fibre-optic spectrometer ready for the end-user. Gives examples of applications within the food and drink industry. Findings - Finds that these instruments are fast, effective and inexpensive, and rugged enough for the processing environment. Originality/value - Draws attention to the potential of NIR spectroscopy outside the confines of the laboratory.

Notes: Purpose - Describes the history and development of biosensors and their commercial application. Design/methodology/approach - Provides background information on different forms of biosensors and how they can be brought to market. This review is edited from a very detailed market research report "Medical and Biological Sensor and Sensor Systems: markets, applications and competitors worldwide". Findings - Finds that the commercial potential for biosensors is very large and is expected to reach US$ 2.3 billion worldwide in 2005. Originality/value - The full market research report provides a detailed insight into biosensors and how they are made and the various application areas, together with discussion regarding a large number of vendor and research companies.

Notes: Purpose - Introduction of an automated laboratory system for a new field of laboratory operation, namely cultivation and handling of live brain tissue. Design/methodology/approach - The company's expertise in manual throughput was transferred to automatable methods. Processing data is used for scheduling purposes to yield efficient production of results. Findings - Automated process has comparable survival rates and high reproducibility. Time tolerance is lower than for manual operation. Research limitations/implications - Several bottle necks of the system have been identified and are to be improved upon in future research. These are especially "handling of membrane inserts" and slow-running procedures. Practical implications - Cataloging of activity data (timestamps, parameters, etc.) allows for much easier statistical analysis and data-mining than with manual operation data. Originality/value - Tissue-based, high-throughput screening is a seminal field in laboratory automation.

Notes: Purpose - This paper describes a method for patterning fine line interconnections over non-planar surfaces and introduces the idea of using holographic masks for more challenging geometries. Design/methodology/approach - A photolithographic method for achieving grossly non-planar interconnects is described. The patterning of electrical interconnections onto the piezo-electric actuators of an ink-jet print head is used as an example. Uniform coverage of the substrate is achieved using an electro-depositable photoresist. The required pattern is transferred via a custom-designed chrome-on-glass mask using a standard mask aligner. Findings - Large arrays of 100?µm-pitch electrical interconnections were successfully deposited onto 500?µm-high high piezo-electric actuators. It was necessary to modify the shapes of the line segments on the mask in order to compensate for diffractive line broadening. For more extreme 3D geometries it becomes necessary to consider the use of holographic masks. Originality/value - Printed circuit boards and semiconductor wafers are nominally flat and traditional lithographic processes have been developed accordingly. However, future microelectronic packaging schemes and microsystems may require patterning to be achieved on grossly non-planar surfaces. We have demonstrated that this can be achieved on ink-jet print heads using photolithography and point to the research necessary to enable it to be realised on more extreme non-planar substrates.

Notes: Purpose - This paper focuses on the project "Development of electronic components on circuit boards made of renewable resources" which has the aim of developing materials and technologies for the production of electronic components with printed wiring boards (PWB) completely made of renewable resources. Design/methodology/approach - Reviews the use of renewable resources in the electronics industry where there is potential for fostering sustainable development through its technological innovations. Findings - Outlines that ARBOFORM, a high-quality thermoplastic engineering material for applications that demand high technological standards, combines the positive properties of natural wood with the processing capabilities of thermoplastic materials. Originality/value - The motivation for the substitution of non-renewable raw materials is not only given by ecological aspects but could also be boosted in future as reserves of fossil resources are further depleted and costs increase.

Notes: Purpose - This paper describes the different thickness measurement techniques that enable reliable thickness assessments, and the determination of the recommended immersion tin thickness for lead-free soldering. Design/methodology/approach - Immersion tin layers were prepared with systematically varying layer thicknesses. The samples were annealed at different reflow profiles, used in assembly for tin/silver/copper (SAC-alloy) soldering. The layers were characterized with X-ray fluorescence, electrochemical stripping coulometry, and by examining the cross sections using a scanning electron microscope. The solderability of the samples was determined with a solder balance (Solderability Tester Menisco ST60) using a SAC-alloy (melting point 217°C) with T(max) at ?T=28°C and ?T=43°C above melting. Findings - If all pure tin is converted into the Sn/Cu IMC, so that no pure tin is left as solderable layer, the wetting behaviour will decrease dramatically. Especially for multiple soldering processes, two times reflow followed by wave soldering, it is essential to have a pure tin layer covering the Sn/Cu IMC before going to the final soldering process. The required amount of residual pure tin over the Sn/Cu IMC is detailed in several papers. It is stated that a minimum of 0.2?µm of pure tin over the Sn/Cu IMC is absolutely necessary to ensure reliable wetting and solder joint formation. With the current immersion tin thickness recommendation of 1?µm, based on the needs of lead containing solder pastes, a residual pure tin layer will not be evident or thick enough to ensure reliable assembly for multiple soldering with lead-free temperature profiles. Originality/value - Helps to enable reliable thickness assessments, and the determination of the recommended immersion tin thickness for lead-free soldering.

Notes: Purpose - To review the concept of digital imaging for PCB manufacturing, with a specific focus on ink-jet printing technologies. Design/methodology/approach - This paper has been written to provide a review of digital imaging in the PCB industry. The application of ink-jet printing in PCB manufacturing and the basic technology behind ink-jet printing is described. Findings - Ink-jet printing in PCB manufacturing is a new technology, whose benefits and liabilities are still being determined. Although the concept of digital imaging fits a need in the industry for better control over registration, there are still many issues to be addressed for the technology to become widely adopted. Originality/value - The value of the paper lies in educating the industry in the concepts of ink-jet printing and the potential benefits it can deliver towards yield improvement and reduced costs in an ever-more demanding and price sensitive market.

Notes: Purpose - Focuses on, and provides a background of, the REACH Regulation, a new system of registration, evaluation and authorisation for chemicals. Design/methodology/application - In October 2003 The European Commission presented to the European parliament and the Council of the European Union (EU), a proposal for a Regulation that will radically reform Europe's existing chemical policy. The so-called REACH Regulation will introduce a new system of Registration, Evaluation and Authorisation for Chemicals introduced on the EU market in volumes over 1?tonne per manufacturer per year. It will also establish a central Chemicals Agency to oversee the efficient operation of the new regulatory system. The implications of the draft Regulation on Europe's chemical manufacturers, importers, formulators and those sectors that either use or process chemicals, such as the electronics industry, will be manifold. Findings - Despite a number of concessions granted to the chemical industry following an internet consultation, there remain serious doubts over the workability of the system, as well as concerns over substantial product losses and fears over the competitiveness of Europe's chemical industry. Originality/value - This paper sets out to provide a background to the proposed reforms and an outline of the main components of the REACH system as well as a summary of some of the likely key impacts on the PCB industry.

Notes: Purpose - To review a newly developed PCB fabrication process based on a parallel lamination technique. Design/methodology/approach - This paper has been written to introduce the SAVIA process, a new parallel lamination technique for PCB fabrication. The basic concept of the SAVIA process has been described along with the individual process steps and the reliability issues. The advantages of SAVIA process have been also discussed in both economical and technological aspects. Findings - It was found that the parallel lamination technique, a key process for SAVIA, was not only highly flexible and reliable but also a cost-effective fabrication method for high performance PCB. With the SAVIA process, manufacturing lead-times can be substantially reduced due to the nature of the parallel processing. It was also confirmed that a highly reliable metal alloy interconnection was created between the core and the adhesive layers during the lamination process. The formed metal alloy contacts showed excellent electrical and physical characteristics. The between layers was precise. Originality/value - The value of this paper is to introduce a novel PCB fabrication process based on a parallel lamination technique that is superior to conventional build-up processes from both technological and economical viewpoints. By applying a parallel lamination technique, it is expected that fabrication costs can be lowered due to reductions in manufacturing lead-time.

Notes: Purpose - To study the influence of storage time and environment on the solderability of electroless nickel plated samples with Sn-3.8Ag-0.7Cu and Sn-3.5Ag lead-free solders and to provide criteria for the use of an electroless nickel (Ni-P) under bump metallization (UBM) without immersion gold protection. Design/methodology/approach - Electroless nickel coatings were deposited onto pure aluminium foil through a procedure developed for the UBM of wafers prior to flip chip bumping. Their solderability with lead-free solders was studied using the wetting balance technique. Samples stored in different environments for different periods of time were tested to study the dependence of the solderability of Ni-P coatings on the storage time and temperature. The degree of oxidation of the Ni-P coatings was examined by means of X-ray photoelectron spectroscopy and the surface microstructure and roughness of the coatings were analyzed by scanning electron microscopy and atomic force microscopy. Findings - It was found that the Ni-P coatings were unacceptable for direct soldering without the assistance of a flux, due to poor wettability, even when using a freshly prepared Ni-P coating. Therefore, a suitable flux with nitrogen inerting had to be applied to assist the soldering process. The results also show that the solderability of Ni-P coatings was affected by the phosphorus content, and the Ni-P coating with high phosphorus content had a good solderability. The storage time and temperature did not influence the wettability significantly with the assistance of strong flux. Research limitations/implications - The stability of the plating solution and the consistence of the phosphorus content in the coating are not easily controlled. This has resulted in implications for surface analysis and wetting testing. Ni-P coatings with different levels of phosphorus content are being investigated in detail. Originality/value - The value of the paper lies in its study on the solderability of lead-free solders to Ni-P coating after storage in different environments and for different periods, which can provide some criteria for the use of Ni-P UBM without immersion gold protection.

Notes: Purpose - To present the initial results from a project recently undertaken by Rohm and Haas Electronic Materials Europe Ltd, in collaboration with a number of European partners, to develop individual elements of the traditional PCB manufacturing process towards a sustainable and zero-discharge alternative. Design/methodology/approach - This paper presents initial results from work aimed at enabling PCB manufacturing to become more sustainable. Novel processes evaluated include special electroplating techniques, advanced oxidation methods to remove organic contaminants, and new ion exchange systems. Work has been carried out to develop these processes into viable demonstrators and the results of progress to date are reported. Descriptions of how these individual technologies may be combined to provide an integrated approach to a more sustainable PCB manufacturing methodology are also given. Findings - Initial results indicate that a more sustainable PCB manufacturing process may be achieved by combining the use of organic and metal capture resins with advanced oxidation and electrochemical recovery technologies. Originality/value - The value of the paper lies in its provision of information from a project that is integrating available treatment technologies in a novel approach that will take the PCB manufacturing process closer to a zero effluent discharge situation.

Notes: Purpose - To give an overview of the issues encountered, and changes that need to be made in the various types of soldering process when converting them from conventional to lead-free assembly. Design/methodology/approach - This paper has been written to provide a review of the lead-free reflow, wave and hand soldering processes. Problem areas highlighted and methods for adjusting and optimising each type of soldering process for compatibility with lead-free solders are described. Findings - The move to lead-free soldering in electronics assembly can lead to a number of issues that affect process performance, yields and reliability. Problems that are sometimes encountered with conventional lead-bearing solders can exacerbated when moving to lead-free. Many of the issues are associated with the higher melting points of the recommended lead-free solders. Fortunately, these issues are now well known and, with care and attention to process optimisation, they can largely be avoided. Originality/value - The value of the paper lies in its ability to provide information on the types of problems and issues encountered when moving to lead-free solders and the advice it gives on how to avoid them. It also describes how to convert the various lead-free soldering processes used in PCB assembly using a range of measures that can minimise defects, avoid common problems and optimise yields. Sources of additional assistance are also identified.

Notes: Purpose - Aims to explain the main requirements for printed circuit boards (PCBs) and to determine the survival rate of boards in lead-free assembly. Design/methodology/approach - The first two main requirements are the survival of 5-6 cycles lead free reflow with peak temperatures of up to 260°C and an identical or even better board reliability of such boards compared to todays eutectic soldered ones. In a first series of tests the influence of base materials, reflow temperature gradient and peak temperature on PCB survival rate are investigated. Thermo-mechanical data of different epoxy-based materials are compared to survival rate investigations using repeated reflow tests. The impact of PCB manufacturing and design on the lead free performance is discussed. A second series of investigations is air-to-air life cycle tests of daisy chain boards out of different epoxy-based materials with varying preconditioning were done. Findings - The tests showed that dicy cured epoxy base materials are not able to withstand the thermal stress of the mentioned soldering steps. Board design and the heating gradient in reflow also influence the assembly performance. Thermal cycling tests (air-to-air), showed clearly the effect of reflow temperature and number of reflow cycles on through-hole reliability. There was no significant impact of z-axis-expansion on the through-hole failure rate in air-to-air cycling. Originality/value - Provides further information on the lead-free assembly of PCBs.

Notes: Purpose - This paper aims to explain how the goals have been met to manufacture rigid-flex printed circuit boards (PCBs) in equipment used for rigid PCBs by utilizing new materials and process combinations. Design/methodology/approach - A discussion of the technology and applications. Findings - The main drivers for PCB technology have been size reduction, increased resolution, improved high frequency performance together with increased reliability and cost savings. To reach higher packaging density at the PCB level, Aspocomp has developed the technology with embedded active and passive components. However, in higher packaging density applications, the PCB-technology has to offer more flexibility to PCB-designers in order to effectively utilize space inside the electronic devices. Different flexible PCB solutions are needed to achieve this goal. Practical implications - For fabricators of rigid PCBs there are challenges in production to adopt the new industry requirements. Originality/value - This paper is of value to those involved with or interested in PCB technology.

Notes: Purpose - There are many considerations that have to be taken into account when balancing the properties epoxy-based laminate and prepreg materials must have in order to meet the array of electrical, thermal and mechanical demands of today's multilayer printed circuit boards. Aims to discuss two different curing systems that are commonly employed in current laminate and prepreg materials. Design/methodology/approach - An examination of the two different curing systems - phenol novolac (PN) and dicyandiamide (DICY) based - that are commonly employed in current laminate and prepreg materials. Findings - DICY curing systems have properties such as good flexibility, good adhesion and good processability but have poor thermal resistance, higher water absorption and poor anti-CAF capability. Because PN resin systems utilize an aromatic ring structure, traditional PN cured epoxy resin results in having excellent thermal resistance, low water absorption and anti-CAF capability. Originality/value - Provides a comparison of interest to all those involved with laminate and prepreg materials in the circuit board industry.

Notes: Purpose - To review opportunities for use of digital printing in the printed circuit board (PCB) industry and to introduce background to ink jet printing, process development and applications in order to reduce costs, enhance efficiency and to enable PCB producers to operate in a more sustainable and flexible manner. Design/methodology/approach - This paper has been written to provide a review of ink jet printing applications in the PCB industry. Ink jet print technology background, ink development and the processes made possible by ink and print head improvements have been described together with a description of the benefits available through digital printing. Findings - It was found that there have been significant developments over recent years in both hardware technology (print heads and accurate print platforms) as well as improvements in the design of inks both for ink jet print performance and functional characteristics. These improvements have been integrated to provide an exciting new technology which can be applied in the manufacture of PCBs to reduce manufacturing costs and increase flexibility of manufacture. Originality/value - The value of the paper lies in its ability to provide information on the scope of opportunities for ink jet printing in the PCB manufacturing process through the use of a range of new inks having specific properties. The design and development of highly accurate machinery provides the opportunity to attain the desired print resolution.

Notes: Purpose - The aims of the paper are to improve the dynamic response of an induction motor based position servo system and to remove the chattering problem in the sliding mode control theory by using fuzzy logic principles. The obtained results are also compared with conventional sliding mode controller to show its performance. Design/methodology/approach - The main method used for the research is to form a thin boundary layer neighboring the switching surface by using fuzzy logic. The sliding mode control law is inherently discontinuous naturally. Therefore, there are some difficulties such as so many switches occurring between the control bounds, which cannot be carried out by real controllers. Therefore, fuzzy logic is used in the thin boundary layer to determine the control signal current. Thus, the chattering is eliminated. Findings - The results show that the designed controller has superior performance. But, there are also some difficulties. It is difficult to obtain fuzzy rules. The rules can be obtained by using genetic algorithms without expert's knowledge. However, sliding surface slope C can be optimized to increase system's dynamic performance. Originality/value - A new boundary layer consisting of the fuzzy rules in the sliding mode control is formed.

Notes: Purpose - Nonlinear dynamical systems may, under certain conditions, be represented by a bilinear system. The paper is concerned with the construction of the controllability and observability gramians for the corresponding bilinear system. Such gramians form the core of model reduction schemes involving balancing. Design/methodology/approach - The paper examines certain properties of the bilinear system and identifies parameters that capture important information relating to the behaviour of the system. Findings - Novel approaches for the determination of approximate constant gramians for use in balancing-type model reduction techniques are presented. Numerical examples are given which indicate the efficacy of the proposed formulations. Research limitations/implications - The systems under consideration are restricted to the so-called weakly nonlinear systems, i.e. those without strong nonlinearities where the essential type of behaviour of the system is determined by its linear part. Practical implications - The suggested methods lead to an improvement in the accuracy of model reduction. Model reduction is a vital aspect of modern system simulation. Originality/value - The proposed novel approaches for model reduction are particularly beneficial for the design of controllers for nonlinear systems and for the design of radio-frequency integrated circuits.

Notes: Purpose - This paper aims at developing a computational technique to take account of the laminated nature of iron cores when computing their eddy current losses. Design/methodology/approach - A method is presented to compute three-dimensional eddy current distributions in laminated media by means of the finite element method. In a first step, the laminated medium is assumed to have an anisotropic conductivity with zero (or very low) value in the direction normal to the laminations. In a second step, the eddy currents within the laminates are computed by solving the quasistatic electromagnetic field individually in each sheet. In these essentially two-dimensional analyses, the boundary conditions are taken from the three-dimensional field distribution determined in the first step. Findings - Comparisons with results obtained from a finite element model taking account of each laminate prove the validity of the method. Research limitations/implications - The method is presented for linear media only. Taking account of nonlinearity is an important future topic. Originality/value - Taking account of the laminations by treating the magnetic field distribution obtained from a homogenised model is a novelty of potential benefit to researchers developing methods of loss computation in laminated media.

Notes: Purpose - Characterisation and use of dielectric materials with high permittivity are one of the most developed areas of research in microwave circuit simulation. This is mainly because of their various applications in VHF/UHF and microwave frequencies (correlators, instrumentation systems, ...). The primary virtue of high-dielectric substrates for microwave circuits is the reduced size. Since the high dielectric microstrip line also exhibit low loss and useful impedance range, this class of circuits will undoubtedly find wide applications in microwave integrated circuitry. Design/methodology/approach - Owing to the complexity of the electromagnetic problem, numerical methods become an indispensable tool for analysis and modeling of electromagnetic structures. They are the basis to set-up computer-aided design (CAD) packages. These models must be accurate, reliable, easily extracted and need limited computational requirements. Since there was a demand for a model able to describe these parameters accurately, an extension of the spectral domain approach (SDA) is proposed for microstrip lines with high permittivity. The analysis is based on the solution of a system of algebraic equations, which are derived from Galerkin's technique in the spectral domain. Findings - Analytical expressions are deduced by curve-fitting techniques. These expressions can be easily implemented in a CAD simulation tool to design wireless communication components. In this paper, we have developed accurate and suitable general expressions for characteristic parameters for a wide range of ?r between 1 and 500. The computed results were compared to those available in the literature when possible. In order to validate our models for high values of dielectric constant (128?〈??r〈500), neural models were generated for the characteristic impedance and effective permittivity. A very good agreement is demonstrated. Originality/value - The originality of this paper consists on the development of design formulas to characterise the microstrip lines with high dielectric constant substrate. Closed form equations are almost non-existent in the technical literature since the available design formulas have been developed only for dielectric media value ?r not exceed 128.

Notes: Purpose - The investigation of the efficiency of optimisation technique based on approximation of objective function by multiquadric (MQ) function, used for induction heating devices was the aim of the paper. Design/methodology/approach - The optimisation package based on Matlab language and using Flux2D commercial program for calculation of electromagnetic and thermal fields was built. It allows the use of different optimisation techniques for induction heating devices, e.g. based on MQ function approximation. In the paper two algorithms of approximated points generating have been tested. Findings - The efficiency of MQ optimisation method strongly depends on the applied algorithm of approximated point generating. To ensure high efficiency of MQ optimisation method, the stochastic element of the algorithm of approximated point generating should have a significant role. Research limitations/implications - The efficiency of elaborated algorithms of MQ function approximated point generating should be proved in other applications. Practical implications - The efficient optimisation technique of induction heating devices has been proposed. Originality/value - The two new algorithms for generation of MQ function approximated points have been proposed. The paper could be useful for designers of induction heating devices.

Notes: Purpose - To produce a controlled stirring in a low conducting liquid thanks to a new kind of multiphase inductor. Design/methodology/approach - An experimental pilot consisting of a cylindrical salt water pool surrounded by an innovative multiphase inductor configuration, based on the single phase asynchronous motor principle, is setup. The maximum bulk stirring velocities are measured and compared with the estimate by numerical modelling. Findings - Shows the possibility of controlling the stirring of a low conducting liquid thanks to a multiphase inductive system. The corresponding measurement results give a significant bulk velocity of a few centimetres per second. Practical implications - This new kind of multiphase inductor, working with a single phase induction generator, seems a promising way to produce a controlled stirring in low conducting media which cover a large range of induction applications. Originality/value - Such an innovative inductor configuration has already been tested successfully for metal alloys stirring in the middle frequency area. In this paper, an extension of this kind of multiphase inductive system for electromagnetic stirring of low conducting liquids like electrolytes in the high frequency area is presented.

Notes: Purpose - Aims to apply the generalized minimal residual (GMRES) algorithm combined with the fast Fourier transform (FFT) technique to solve dense matrix equations from the mixed potential integral equation (MPIE) when the planar microstrip circuits are analyzed. Design/methodology/approach - To enhance the computational efficiency of the GMRES-FFT algorithm, the multifrontal method is first employed to precondition the matrix equations since their condition numbers can be improved. Findings - The numerical calculations show that the proposed preconditioned GMRES-FFT algorithm can converge nearly 30 times faster than the conventional one for the analysis of microstrip circuits. Some typical microstrip discontinuities are analyzed and the good results demonstrate the validity of the proposed algorithm. Originality/value - In the future, some more efficient preconditioning techniques will be found for the mixed potential integral equation (MPIE) when the planar microstrip circuits are analyzed.

Notes: Purpose - This paper proposes an automatic procedure to characterize discrete source fields. Design/methodology/approach - A technique is developed to characterize curl-conform fields to be used as source fields or non-local basis functions in finite element formulations. A reduced characterization of such fields using curl-conform finite elements is defined. An automatic construction of these curl-conform spaces is proposed. Findings - A reduced characterization of such fields is shown to be convenient for the coupling with complementary reaction fields and for simply and explicitly defining non-local quantities, such as currents in h-conform magnetodynamic formulations. The reduced form rests on the choice of supports for the fields limited to reduced cut spaces associated with cuts making the definition domain simply connected. Originality/value - Develops a procedure to simplify the construction of curl-conform source fields.

Notes: Purpose - To investigate the feasibility of a novel scheme of high-efficiency induction heater for nonmagnetic metal billets which use superconducting coils. Design/methodology/approach - The idea is to force the billet to rotate in a static magnetic field produced by a DC superconducting magnet. Since a static superconducting magnet has no losses, the efficiency of the system is the efficiency of the motor used. In order to evaluate the temperature distribution arising from the field profile produced by a given SC coil configuration, a numerical model, based on an equivalent electric network with temperature-dependent parameters, is developed. Findings - A substantial independence of the shape of the temperature profile on the angular velocity and the value of the uniform magnetic field applied, is observed. A strong temperature gradient is observed in the radial direction in the proximity of the penetration front and in the axial direction at the top and bottom surface of the billet. Small temperature gradient was observed in the central part of the billet. Research limitations/implications - The reported temperature profile is inadequate for an actual extrusion process which is desired to happen at a constant temperature. The appropriate profile along the billet length can be achieved by a suitable axial shaping of the magnetic field, through the optimization of the coil layout, whereas the undesired radial gradient can be reduced by interspacing the rotation with temperature smoothing intervals. Practical implications - The investigation of the profile of applied magnetic field and the heating procedure which allow to achieve the distribution of temperature suitable for the extrusion process can be carried out by using the present model. Originality/value - A high-efficiency induction heater for nonmagnetic metal billets using superconducting coils in a novel scheme is investigated.

Notes: Purpose - On the basis of the maximum entropy principle, seeks to formulate a hydrodynamical model for electron transport in GaAs semiconductors, which is free of any fitting parameter. Design/methodology/approach - The model considers the conduction band to be described by the Kane dispersion relation and includes both G and L valleys. Takes into account electron-non-polar optical phonon, electron-polar optical phonon and electro-acoustic phonon scattering. Findings - The set of balance equation of the model forms a quasilinear hyperbolic system and for its numerical integration a recent high-order shock-capturing central differencing scheme has been employed. Originality/value - Presents the results of simulations of n+?-n-n+ GaAs diode and Gunn oscillator.

Notes: Purpose - Presents a technique based on the development of an artificial neural network (ANN) model for predicting the electromagnetic inference effects on gas pipelines shared right-of-way (ROW) with high voltage transmission lines. Design/methodology/approach - Examines the induced pipeline voltage under different soil resistivity, fault current and separation distance. Findings - The results indicate strong agreement between model prediction and observed values. Originality/value - Demonstrates that the ANN-based model developed can predict the induced voltage with high accuracy. The accuracy of the predicted induced voltage is very important for designing mitigation systems that will increase overall pipeline integrity and make the pipeline and appurtenances safe for operating personnel.

Notes: Purpose - To present a new parallel method for solving differential equations that describe transient states in physical systems. Design/methodology/approach - The proposed speculative method first solves a differential equation with a large integration step to determine initial data for parallel computations in sub-intervals of time, then speculatively computes in parallel solutions in all the sub-intervals with a smaller integration step and finally composes the final solution from the speculatively computed ones. The basic numerical method applied is the well-known Runge-Kutta algorithm. Findings - The speculative method allows important reduction of the computation time of sequential algorithms. The speed-up of the speculative method that we propose, as compared to the sequential execution, depends on the number of sub-intervals that are defined inside the total analysed time interval. The speed-up increases almost linearly with the number of sub-intervals. The good accuracy of computations in the presented example was obtained. Research limitations/implications - The proposed method can be applied to non-linear systems without discontinuity points and to stable systems (i.e. systems insensitive to the selection of initial conditions). Practical implications - The method can be especially applied for long-lasting computations with a slow convergence of state variables values along with the decrease of integration steps. Originality/value - The paper presents an original parallel method for solving differential equations, which significantly speeds up transient states analysis in physical systems.

Notes: Purpose - Developing an efficient second-order integration method of transient analysis of nonlinear dynamic circuits which overcomes the main drawback of the trapezoidal rule. Design/methodology/approach - Dynamic circuits including transistors and operational amplifiers are considered. A new family of two-step, second-order numerical integration algorithms has been developed using a polynomial approximation. Findings - The algorithms have been worked out which are implicit, A-stable and they depend on a parameter which is allowed to be changed during the computation process according to a proposed strategy. Also the variable step-size formula has been derived enabling us to eliminate a restarting procedure. The method has been implemented and tested using several representative circuits. It has been compared, both theoretically and via numerical examples, with the alternative well known algorithms: the trapezoidal rule and the backward differentiation formula of order two. Research limitation/implications - The algorithms developed in the paper are two-step and second-order, consequently the step size cannot be too large and the algorithms are not L-stable. Originality/value - A new family of two-step implicit integration algorithms is developed. It can be useful for the analysis and design of electronic circuits.

Notes: Purpose - To propose a novel method for defect reconstruction in electromagnetic non-destructive testing (NDT). Design/methodology/approach - The inversion method is based on an optimized database that contains the measured signals for some predefined defect prototypes. The database is supported by an anisotropic simplex mesh, which has been generated adaptively in the abstract n-dimensional space, spanned by the model parameters of the defect type. The actual reconstruction reduces to a mesh search and interpolation. The described theory is demonstrated in the paper by a solved NDT test problem. Findings - We have realized that in addition to sole defect reconstruction, the database provides meta-information about the quality of the inversion, the suitability of the chosen defect model parameters, as well as the capabilities of the testing experiment. Research limitations/implications - Defect models having several parameters require a sophisticated mesh generation algorithm, which works in higher dimensions. Originality/value - In the authors' opinion the mesh database approach offers a totally new point of view of a given inverse problem, and may help in the better understanding of its nature.

Notes: Purpose - The definition of a simple model of low frequency magnetic field created by power industrial installations can be approached by using an equivalent source system (ESS). Given a set of measured magnetic field points, the ESS, made by a limited set of current carrying wires or turns, must be placed and supplied in order to fit the measured magnetic field values. An optimisation procedure can be used to define the current values and the location of the ESS which minimize the error between the measured and computed magnetic field values. Design/methodology/approach - A two-step optimal procedure is defined: in the outer step a stochastic optimisation routine is used to drive the geometric control parameters of the ESS while, in the inner step, the current values flowing through the sources are computed to find the minimization of the error with respect to a set of measured magnetic field values. The optimisation procedure is based on an artificial immune system algorithm which focuses on a deep exploration of the search space and gave interesting results both in terms of accuracy and computational efficiency. Findings - The results show that the proposed approach is able to reconstruct the magnetic field created by complex source system and give some accuracy measure on the reconstruction error. The optimisation process carried out also on conductor positions has allowed to find out the location of the real sources in an accurate way, also in presence of measurement errors. Originality/value - The approach proposed uses optimisation procedures to solve the inverse problem of source reconstruction starting by a set of measured magnetic field values. The definition of a simple equivalent source structure, together with an optimisation procedure to set its control parameters, allows to simulate complex magnetic field sources, like power substations or cable systems, in a very efficient and compact way.

Notes: Purpose - The paper highlights the process of electric vehicles optimal design as an inverse problem and presents the global constrained optimization as the best way to solve it. Design/methodology/approach - The electric vehicle optimal design is carried out by a new approach. It consists an electric vehicle design model managed by constrained optimization techniques. It includes sizing models for all drive train components and a vehicle dynamic model build in a new "design way" as an energy-based model using the response surface methodology. The sensitivity of first simple sizing models can be evaluated by the experimental design method, giving information about the most important part of the model that must be improved. Findings - The result shows the superiority of the constrained optimization technique that treats simultaneously the global optimization and the model adjustment. This method of simultaneous resolution is much more powerful than the successive resolution of each subproblem. The proposed "design approach" used for electric vehicle optimal design offer a large potential in the field of the complex systems design. Originality/value - The electric vehicle design process is treated on a vehicle design model based on a design approach. It allows determining the drive train components specifications for imposed vehicle performances, taking into account the dynamic model of the vehicle and all components interactions. Furthermore, considering fine components sizing models, the components can be sized taking into account the whole system behavior in an optimal global design.

Notes: Purpose - Optimisation in electromagnetics, based on finite element models, is often very time-consuming. In this paper, we present the space-mapping (SM) technique which aims at speeding up such procedures by exploiting auxiliary models that are less accurate but much cheaper to compute. Design/methodology/approach - The key element in this technique is the SM function. Its purpose is to relate the two models. The SM function, combined with the low accuracy model, makes a surrogate model that can be optimised more efficiently. Findings - By two examples we show that the SM technique is effective. Further we show how the choice of the low accuracy model can influence the acceleration process. On one hand, taking into account more essential features of the problem helps speeding up the whole procedure. On the other hand, extremely simple auxiliary models can already yield a significant acceleration. Research limitations/implications - Obtaining the low accuracy model is not always straightforward. Some research could be done in this direction. The SM technique can also be applied iteratively, i.e. the auxiliary model is optimised aided by a coarser one. Thus, the generation of hierarchies of models seems to be a promising venue for the SM technique. Originality/value - Optimisation in electromagnetics, based on finite element models, is often very time-consuming. The results given show that the SM technique is effective for speeding up such procedures.

Notes: Purpose - This paper deals with the collaborative design of electromagnetic devices over the internet network. The design is made by both mechanical and electrical engineers. So, the paper tries to show the importance but also constraints to size such a system using a collaborative optimisation process. Design/methodology/approach - The paper compares two approaches in order to size an electromechanical actuator between mechanical and electrical engineers. In the first one, each profession designs its part, and only common constrained are negotiated. This can result in a design process with many iterations. In the second one, electrical and mechanical engineers built together a common model of the structure and a common list of specifications: this allows a global optimisation that is more efficient. Findings - The main result of the paper is that the second approach in which a global model is built between electrical and mechanical engineers is more efficient. Originality/value - The originality of the paper is to explore the problems and difficulties of an optimisation of an electromechanical device between engineers of different culture working together over the internet network.

Notes: Purpose - The purpose of this paper is to obtain a fully analytical model of an eddy current coupler and to use it in a multi-objective optimisation algorithm. Design/methodology/approach - Analytical expressions of device performances are adopted in the objective function and are obtained from a closed solution of the field problem. The optimisation has been carried out by considering both the torque and the momentum of inertia of the object. Two different structures have been considered. Findings - A fully analytical expression of the torque has been obtained for two different geometrical configurations. The optimisation procedure has been used to compare these structures and it is possible to observe that the DSPM performances are better than the SSPM ones. Research limitations/implications - To obtain a closed form of the torque function, the non-linearities of the iron have been neglected. Nevertheless, in the optimisation procedure has been limited the magnetic flux density in the iron core to a feasible value in the linear part of the ferromagnetic characteristic. The thermal effects have been neglected. Pratical implications - In the industry, eddy current couplers can be used as transmission, dampers and brakes. The use of objective functions (OFs) in a closed formulation allows to perform a light optimisation from the point of view of the time computation and to drastically increase the development efficiency. Originality/value - In this paper, a model for computing the electromagnetic behaviour of eddy current couplers is presented. The optimisation of both the torque and the inertia momentum allows to obtain good static and dynamic performances.

Notes: Purpose - The electroencephalography (EEG) source tomography in bio-electromagnetics is to estimate current dipole sources inside the brain from the measured electric potential distribution on the scalp surface. A traditional algorithm is the low-resolution electromagnetic tomography algorithm (LORETA). In order to obtain high-resolution tomography, the LORETA-contracting algorithm is proposed. Design/methodology/approach - The relation between the dipolar current source J at the nodes in source region and the potential U at the observed points on the scalp surface can be expressed as a matrix equation U=KJ after discretization. K is a coefficient matrix. Usually its simultaneous equation is an under-determined system. The LORETA approach is to find out min?BWJ?2, under constraint U=KJ where B is the discrete Laplacian operator matrix, W is a weighting diagonal matrix. Its solution is J=(WBTBW)-1KT{K(WBTBW)-1KT}+U where {}+ denotes the Moore-Penrose pseudo-inverse matrix. The improvement on this approach is to establish an iterative program to repeat LORETA and reduce the number of unknown J quantities in the step i+1 by contracting the source region excluding some extreme little quantities of J given in the step i. The simultaneous equations will gradually turn to a properly determined system or to an over-determined system. Finally, its solution can be obtained by using the least square method. Findings - Repeating to make the low-resolution tomography by contracting the source region, we can get a high-resolution tomography easily. Research limitations/implications - The LORETA-contracting algorithm is based on the assumption that the dipolar current sources inside the brain are sparse and concentrated based on the physiological study of the brain activity. Originality/value - It is new to repeat LORETA combined with the contracting technique. This algorithm can be developed to solve EEG problems of realistic head models.

Notes: Purpose - To design an optimal active shield for the mitigation of the magnetic stray field around an induction heating device. Design/methodology/approach - The active shield consists of several compensation coils in series and generates a counter field opposite to the main field. One extra compensation winding - the "generating compensation winding" (GCW) - is positioned close to the excitation coil and works as the secondary winding of a transformer. The power in this winding is used to drive the other compensation coils (the active shield), which are the load of the transformer. A circuit with passive components is inserted between the GCW and the other compensation coils. The shield is optimal if it achieves a high field reduction, while the energy dissipation is low. By using a genetic algorithm (GA) that minimizes an objective function, the optimization algorithm finds the optimal geometry and the optimal current for the GCW and the other compensation coils. The objective function uses time harmonic and axisymmetric finite element calculations. Findings - The transformer driven active shield reduces the magnetic field effectively. It is cheap and easy to build, but it works well only for one frequency. Research limitations/implications - The shield is sensitive to tuning of the passive circuit and to changes in the frequency of the induction heater. Practical implications - This transformer driven shield is an alternative for the classical active shield with external power supply. Originality/value - An active shield that does not need an external power supply is a cheap solution for the shielding of magnetic fields.

Notes: Purpose - The parameters of axial-field machines are very small compared with the parameters of conventional machines. Different measuring methods are normally used in order to obtain good estimates of the machine parameters. These methods are difficult to perform, costly and time consuming. This paper proposes the use of genetic algorithms to predict the self and mutual inductances of a specific type of axial-field machine, the Torus motor. Design/methodology/approach - The parameter extraction is reformulated as a search and optimization problem in which the only requirement is a set of values of current versus time and an approximate estimate of the parameters. Findings - The predicted machine self and mutual inductances are verified by comparing with several measuring methods and excellent agreement is obtained. Originality/value - Demonstrates that genetic algorithms can predict the self and mutual inductances of the Torus machine automatically with high accuracy.

Notes: Purpose - The purpose of the paper is to present a novel design method for the optimal finite word length (FWL) finite impulse response (FIR) filters. Design/methodology/approach - The design method is based on a parallel tabu search (TS) algorithm which uses the crossover operator of the genetic algorithm. Findings - Three design examples have been presented to show that the proposed method can provide a good solution to the design problem of a FWL FIR filter. In order to show the validity of the proposed method, the performance of the suggested method has been compared to those of widely-used other methods. From the comparison results, it was concluded that the proposed method can be efficiently used for the optimal FWL FIR filter design. Research limitations/implications - The number of examples can be increased and also the performance of the proposed method might be compared to other design methods, apart from those presented in this work, developed for the design of optimal FWL FIR filters. Practical implications - The use of this method produces optimal digital FWL FIR filters with low complexity and therefore provides advantages in the terms of speed and cost. Originality/value - The originality is the application of the parallel TS algorithm described by the authors to the FWL FIR filter design. The work presented in the paper is particularly important for the researchers studying on the design methods for FWL FIR filter design and the applications of these type filters.

Notes: Purpose - To provide a new and simple inverse rotor time constant identification method which can be used to update an indirect rotor field oriented controlled (IRFOC) induction motor algorithm. Design/methodology/approach - Two different equations are used to estimate the rotor flux in the stator reference frame. One of the equations is a function of the rotor time constant, rotor angular velocity and the stator currents. The other equation is a function of measured stator currents and voltages. The equation that uses the voltage and the current signals of the stator serves as reference model, however, the other equation works as an adjustable model with respect to the variation of the rotor time constant. Voltage signals used in the reference model equation are obtained from the measured DC bus voltage and the inverter gating signals. The proposed scheme is verified using a MATLAB/SIMULINK model for two different motors and experimentally using a DSP development tool (MCK 243) supplied by Technosoft S.A. Findings - The proposed estimator was able to successfully track the actual value of the inverse rotor time constant for different load torque and speed operating conditions. Increased oscillations in the estimated inverse rotor time constant appeared at lower speeds (below 10 per cent of rated speed) due to drift in a PI regulator (used at the estimator side), which was tuned under rated operating conditions and using parameters nominal values. Research limitations/implications - This estimation scheme is limited when near zero speed operation is demanded; otherwise it gives a simple and practical solution. A suggested way out of this, is to provide a self-tuning controller that can automatically adjust even for zero speed operation, or to automatically disconnect the estimator and take the most updated value as long as the operating speed is below a predetermined value. Originality/value - This paper presented a new inverse rotor time constant estimator for an IRFOC induction motor application and in conjunction rotor flux was estimated without voltage phase sensors.

Notes: Purpose - This paper presents a novel multiobjective optimal design of three phase induction motor using simulated annealing (SA) technique for minimizing annual material cost and annual loss cost as two objectives. Design/methodology/approach - The design problem of a three-phase induction motor is presented as a nonlinear multicriterion optimization problem on the basis of minimizing the annual cost of the motor. The annual cost referred is the sum of the annual interest and depreciation of motor active material costs, annual cost of active power loss of the motor and the annual energy cost required to supply such power loss. A computer package is built which generates initial values of motor parameters and gives the optimal values of these parameters with more than one objective function and nonviolated constraints. The problem is solved by giving weights which reflect the priority of objective functions. The SA technique is used as a tool to solve the problem. Findings - To verify the validity, the proposed method is applied to a three-phase induction motor design. From the results, it is found that the proposed method is fast and efficient and hence it is useful for multiobjective design of an induction motor. Originality/value - This method is particularly useful in satisfying the needs of motor producer and consumer by prioritizing their needs and finally arriving at a best compromise solution.

Notes: Purpose - To study the magnetic shielding and the losses of non-linear, hysteretic multilayered shields by using fast to evaluate analytical expressions. Design/methodology/approach - In order to evaluate the shield in the frequency domain, the non-linear shield is divided into a sufficient number of piecewise linear sublayers. Each sublayer has a permeability that is constant (space independent) and complex (to model hysteresis). This expression for the permeability is found from the Preisach model by a Fourier transform. Once H is known in the entire shield, analytical expressions calculate the eddy current losses and hysteresis losses in the material. The validity of the analytical expressions is verified by numerical experiments. Findings - In the Rayleigh region, the shielding factor of perfectly linear material is better than the one of non-linear metal sheets, but also the eddy current losses are higher. The results of the optimization show that steel is only a useful shielding material at low frequencies. Research limitations/implications - The analytical method is valid for infinitely long shields and for weak imposed fields in the Rayleigh region. Practical implications - As the analytical expressions can be evaluated very fast (in comparison with slow finite elements models), many magnetic shields can be compared in parametric studies. Originality/value - Analytical expressions exist for the shielding factor and the losses of linear materials. In this paper, the method is extended for non-linear hysteretic materials. The effects of several parameters (material parameters, incident fields parameters) on the shielding and the losses are shown.

Notes: Purpose - To analyze the operating performance of a fuzzy logic control (FLC) based solar energy conversion modular system controlled by a digital signal processor (DSP) microcontroller. Design/methodology/approach - A range of published works relevant to the solar energy conversion modular systems are evaluated and their limitations are indicated in the first section of the paper. The circuit diagram of the panel-boost converter system is described in the second section. In the third section, a neural network model is suggested for the photovoltaic panel and the model is created in the MATLAB/SIMULINK and then combined with other blocks existing in the system. The design of the FLC method is described in section 4. The simulation and experimental results corresponding to the control of the duty-cycle of the converter to set the operating point of the solar panel at the maximum power point (MPP) are given in sections 5 and 6, respectively. Section 7, summarizes the results and conclusions of the study. Findings - The paper suggests a simple dc-dc boost converter controlled by FLC method. The proposed converter model can be used to obtain maximum power from a photovoltaic panel. Research limitations/implications - In preparing this paper, the resources books existing in the library of our university and the resources relative to the solar energy conversion and FLC published in English language and reachable through the internet were researched. Practical implications - The paper suggests a neural network model for a solar panel, which can be used in the simulation of the solar energy panel-boost converter system. The solar energy panel-boost converter system proposed in this study can be used by the researchers who are working in the solar energy conversion area. Originality/value - The suggestion of a neural network model for a solar panel and creation of this model in the MATLAB/SIMULINK environment provides researchers to simulate and to analyze the performance of the solar energy panel-boost converter system using the MATLAB/SIMULINK simulation program. In addition, since the control approach proposed in this paper does not require the information on temperature and solar irradiance that affect the maximum output power, can effectively find the MPP of the solar panel.

Notes: Purpose - Analytical models are often used in the first steps of the design process. They are associated with optimisation methods to find a solution that fulfil the design specifications. In this paper, the analytical model of an electric motor is built and proposed as a benchmark to highlight the optimisation methods the most fitted to analytical models. Design/methodology/approach - This paper studies the optimal design of a brushless DC wheel motor. First, the analytical model is presented. Each equation used for the sizing is described, including the physical phenomenon associated, the hypotheses done, and some precautions to take before computing. All equations are ordered to ease their resolution, due to a specific procedure which is then described. Secondly, three optimisation problems with an increasing number of parameters and constraints are proposed. Finally, the results found by the sequential quadratic method point out the special features of this benchmark. Findings - The constraint optimisation problem proposed is clearly multimodal as shown in the results of one deterministic method. Many starting points were used to initialise the optimisation methods and lead to two very different solutions. Originality/value - First, an analytical model for the optimal design is detailed and each equation is explained. A specific procedure is presented to order all equations in order to ease their resolution. Secondly, a multimodal benchmark is proposed to promote the development of hybrid methods and special heuristics.

Notes: Purpose - To provide a new method and methodology for researches and academic members which can help them to develop scientific work. Design/methodology/approach - The paper presents closed-form expressions for the harmonic components of the space-vector pulsewidth modulated (PWM) waveforms under inverter fault-mode operations. The main method that is used is the Laplace transform and Fourier series expansion theorem. Findings - Provides information about harmonic sources and its influence on the behavior of the induction machine. Practical implications - The calculated harmonics show a very close agreement with measured harmonics from an experimental digital signal processor (DSP) based modulator. It provides a very useful source of theoretical and practical information for scientific and research area. Originality/value - The method is original and has not been published before. The new and original approach is given by the use of the Laplace transform of space-vectors in the complex plane. This will help to understand harmonics which are formed in four-switch voltage source inverter.

Notes: Purpose - To provide an efficient numerical eigenvalue solution for open waveguides with lossy anisotropic materials. Design/methodology/approach - Vector edge elements are used to represent the core of the problem, and an adaptive perfectly matched layer (PML) is used to truncate the surrounding region. The parameters of the PML are allowed to change at each frequency to obtain accurate results using small number of unknowns. Findings - The method is able to solve many configurations, and considerable reduction in mesh size has been reported. In addition, by adapting the solution according to some error criterion, it will be possible to minimize the dependence on human experience and rely more on automated algorithms. Research limitations/implications - There is a need to improve the performance of the adaptive algorithm by building an automatic adaptive procedure that can work without human intervention. Practical implications - A systematic full-wave algorithm for solving practical electromagnetic engineering problems associated with open waveguides, such as planar transmission lines and optical waveguides, using relatively small computer resources. Originality/value - Proposed a new "dimension" of adaptation for PML, besides the classical h-/p-/hp adaptation methods available in literature. Thus, the requirement for smaller computer resources makes this method cost-effective for industry in the design of practical open waveguides.

Notes: Purpose - Focuses on steady state modelling of basic unipolar non-isolated PWM AC line matrix-reactance choppers (MRC). Their single-phase topologies are similar to well-known basic DC/DC converter ones. The MRC are built up through the adaptation of DC/DC converter topologies, which are based on the substitution of self-commutated unidirectional switches by bi-directional ones. Design/methodology/approach - Presents an approach to modelling of the MRC with averaging operator different to the one used in averaged modelling of the DC/DC converters. There is running averaging of each switching period in the proposed approach. Following this, there is a demonstration of the solutions convergence of the state space and averaged state space equations for infinitive switching frequency. Findings - The running averaging of each switching period should be used if averaged state space method is applied to the analysis of presented choppers. A circuit averaged model build-up procedure of the presented choppers is the same as for the DC/DC ones. Originality/value - Presents a quantitative assessment of accuracy for the averaged models of the presented MRC for finite switching frequency.

Notes: Purpose - This paper describes models of micro-turbines and fuel cells, which can be used in stability studies. Design/methodology/approach - The plants models derived are based on the main equations. These models are developed in the Laplace domain and transient simulation is done using a software developed based on the MATLAB package. Findings - The micro-source is capable of providing effective load-following service in the distribution system. However, the results also show that the micro-source is not an uninterruptible power supply and does not protect the load from voltage instability while in grid-connect mode. When a micro-turbine plant is connected to a point where it gives support to a load in fault conditions, the lower the inertia of micro-turbine plant, the greater is the destabilizing tendency for faults in the distribution system. On the other hand, transient stability is enhanced with aid of the SOFC inverter. Originality/value - The effects of these micro-sources on the network performance are shown and a distribution system embedded with the micro-sources is used as an example. Finally, transient stability and voltage stability of the system are investigated.

Notes: Purpose - To introduce a Whitney-element based coupling of the Finite Element Method (FEM) and the Boundary Element Method (BEM); to discuss the algebraic properties of the resulting system and propose solver strategies. Design/methodology/approach - The FEM is interpreted in the framework of the theory of discrete electromagnetism (DEM). The BEM formulation is given in a DEM-compatible notation. This allows for a physical interpretation of the algebraic properties of the resulting BEM-FEM system matrix. To these ends we give a concise introduction to the mathematical concepts of DEM. Findings - Although the BEM-FEM system matrix is not symmetric, its kernel is equivalent to the kernel of its transpose. This surprising finding allows for the use of two solution techniques: regularization or an adapted GMRES solver. Research limitations/implications - The programming of the proposed techniques is a work in progress. The numerical results to support the presented theory are limited to a small number of test cases. Practical implications - The paper will help to improve the understanding of the topological and geometrical implications in the algebraic structure of the BEM-FEM coupling. Originality/value - Several original concepts are presented: a new interpretation of the FEM boundary term leads to an intuitive understanding of the coupling of BEM and FEM. The adapted GMRES solver allows for an accurate solution of a singular, unsymetric system with a right-hand side that is not in the image of the matrix. The issue of a grid-transfer matrix is briefly mentioned.

Notes: Purpose - To provide a validation of a three-dimensional (3D) macroscopic model for superconductors comparing numerical to experimental AC losses of a BSCCO-2223 tape subject to an orthogonal magnetic field and a transport current. Design/methodology/approach - We solve in 3D geometries the eddy current problem in presence of superconductors, represented by a power-law characteristic rewritten into a variational form. An integral formulation of the magneto-quasistatic Maxwell's equations is used. The solution of the problem is found by an unconstrained minimization of a suitable functional. The numerical results on AC losses computation are compared to experimental data. Findings - The agreement between numerical and experimental data is good in a wide range of currents and magnetic fields. Research limitations/implications - The magnetic field is assumed to be orthogonal to the tape. Different incidence angles should be taken into account. Practical implications - It is possible to extend the range of validity of the engineering formulae for AC losses used in the work. Originality/value - The paper provides a validation of a numerical code against experimental results: this is always challenging in the field of applied superconductivity.

Notes: Purpose - The aim of the present work is to find an efficient solution concerning the computational effort of quasi-static electric field (QSEF) problems involving anisotropic conductivity and permittivity in the frequency domain. Design/methodology/approach - Numerical simulations are carried out with tetrahedral nodal finite elements of first- and second-order and with Withney elements. The solution of the boundary value problem with the aid of the electric scalar potential approximated by nodal finite elements is compared with those by the electric current vector potential represented by edge finite elements. Findings - The simulation with an electric current vector potential approximated by the edge elements of first-order prevail over that by the electric scalar potential approximated by nodal elements of second-order concerning the memory requirements and the computation time at comparable accuracy. Originality/value - The application of edge finite elements to solve QSEF problems considering an anisotropic complex conductivity in 3D.

Notes: Purpose - To establish a statistical formulation of robust design optimization and to develop a fast optimization algorithm for the solution of the statistical design problem. Design/methodology/approach - Existing formulations and methods for statistical robust design are reviewed and compared. A consistent problem formulation in terms of statistical parameters of the involved variables is introduced. A novel algorithm for statistical optimization is developed. It is based on the unscented transformation, a fast method for the propagation of random variables through nonlinear functions. The prediction performance of the unscented transformation is demonstrated and compared with other methods by means of an analytical test function. The validity of the proposed approach is shown through the design of the superconducting magnetic energy storage device of the TEAM workshop problem 22. Findings - Provides a consistent formulation of statistical robust design optimization and an efficient and accurate method for the solution of practical problems. Originality/value - The proposed approach can be applied to all kinds of design problems and allows to account for the inevitable effects of tolerances and parameter variations occuring in practical realizations of designed devices.

Notes: Purpose - Proposes a non-negative matrix factorization method. Design/methodology approach - Presents an algorithm for finding a suboptimal basis matrix. This is controlled by data cluster centers which can guarantee that the coefficient is very sparse. This leads to the proposition of an application of non-matrix factorization for blind sparse source separation with less sensors than sources. Findings - Two simulation examples reveal the validity and performance of the algorithm in this paper. Originality/value - Using the approach in this paper, the sparse sources can be recovered even if the sources are overlapped to some degree.

Notes: Purpose - This paper deals with closed-loop control of a switched reluctance generator (SRG). Design/methodology/approach - The control objective when generating is to maintain the dc link voltage at the required value while achieving maximum efficiency. Three possible control schemes are presented and their performance is examined by testing on an experimental 12/8 three-phase SRG. Findings - A very simple control scheme that requires no prior characterisation of the SRG, an approach based on the use of an inverse machine model and finally, a control scheme that is aimed at achieving optimal efficiency are described and experimental results for all three are presented. Research limitations/implications - The inverse machine model control scheme and the optimal efficiency control scheme require operation at a constant voltage reference for accurate operation (although this is the case for many generator applications). Possible future research might include the expansion of these control schemes to operation with a variable voltage reference. Practical implications - The importance of maximising efficiency is emphasised with a clear method of deriving the optimal efficiency firing angles described. Originality/value - This paper provides a good overview of SRG operation through the experimental implementation of three separate closed-loop voltage control schemes, each of which is described in detail.

Notes: Purpose - The interface between two conducting fluids in a magnetic fluid dynamics (MFD) problem was identified by means of external magnetic field measurements. Genetic algorithms (GA) were applied to solve the inverse problem.The principal component analysis (PCA) was used to speed up the process of interface reconstruction. Design/methodology/approach - With respect to the experimental results we have designed a general technique for mode identification and/or interface reconstruction. Two main procedures are available to solve the inverse problem, the full interface reconstruction and the principle component analysis (PCA) mode. In the case of full reconstruction, it can be decided whether an algorithm for fast identification of the dominant modes applying a FFT module should be performed or not. The full interface reconstruction applies stochastic optimization methods ((GA) or evolution strategies (ES)) for the estimation of the interface shape characteristics. The main goal of the PCA mode is to find the dominant mode of the interface shape and its amplitude. The PCA mode is realized by means of stochastic optimization methods (GA, ES) and a simple direct searching (DS) using the golden section technique. Findings - PCA with GA procedure enables the identification of the dominant mode of the interface shape between two conducting fluids with sufficient accuracy for simulated magnetic fields. Time of identification is strongly reduced due to a redefinition of the genotype representations in the PCA mode. Accuracy of reconstruction depends on the noise level, i.e. signal to noise ratio and a geometrical model used in the reconstruction phase. The correlation between the noise level and values of cost function for identified modes has been found if a proper geometry modelling is applied. Originality/value - The paper describes a new, fast technique for solving an inverse field problem of a MFD problem where the interface between two conducting fluids has to be identified using a magnetic field tomography measuring system.

Notes: Purpose - As well known, in the finite element method, the calculation and the location of the elements of the matrix C of the coefficients requires a lot of calculation times and memory employment especially for 3D problems. Besides, once the matrix C is properly filled, the solution of the system of linear equations is computationally expensive. Design/methodology/approach - The paper consists of two parts. In the first part, to quickly calculate and store only the non-null terms of the matrix of the system, a geometrical analysis on three-dimensional domains has been carried out. The second part of the paper deals with the solution of the system of linear equations and proposes a procedure for increasing the solution speed: the traditional method of the conjugate gradient is hybridized with an adequate genetic algorithm (Genetic Conjugate Gradient). Findings - The proposed geometrical procedure allows us to calculate the non-null terms and their location within the matrix C by simple recursive formulas. The results concerning the genetic conjugate gradient show that the convergence to the solution of the linear system is obtained in a much smaller number iterations and the calculation time is also significantly decreased. Originality/value - The approach proposed to analyze the geometrical space has been turned out to be very useful in terms of memory saving and computational cost. The genetic conjugate gradient is an original hybrid method to solve large scale problems quicker than the traditional conjugate gradient. An application of the method has been shown for current fields generated by grounding electrodes.

Notes: Purpose - This paper presents CoreLab, a sizing environment for electrical devices, based on a new software component standard, ICAR, which offers the possibility of multifaceted components. CoreLab supports the different steps of the sizing procedure of an electrical device by using an optimisation algorithm. It is open, which means that modules can be added to perform new functionalities. Design/methodology/approach - The design of an electrical device has to comply with more and more constraints. In order to integrate and to manage all of these constraints during a design step, the paper proposes a sizing methodology based on an constrained optimisation by using analytical models of the device, and by encapsulating them into software components. Added to these services for the calculation of the sizing model, other services can be useful for the designer during the optimization phase, e.g. the geometry display of the device for each optimisation iteration. In this way, the approach proposes a new software component standard, Interfaces for Component Architecture (ICAR). It offers the possibility of multi-facetted components. The paper also proposes an integrated environment to manage these software components, and their interactions: Core-Lab. These components are then plugged to an optimisation component (algorithm), which manages the different constraints specified by the designer and finds the optimal sizing of the device. Findings - The paper presents the ICAR standard and an environment to manage ICAR components: Core-Lab: the creation of the components (from an analytical model or an existing computation); the projection from one component standard to another; and the composition of components to create a more complex one. Originality/value - The use of software component approach is useful for the sizing of devices. The paper proposes a new standard to support the different aspects of the use of software components during the design of a device: ICAR. Complementary, an open integrated environment is proposed to use these components: CoreLab, but any environment being modified to accept ICAR standard can use ICAR component. So, components can be used in several environments, for example for calculation or optimisation. Components of different types can be gathered together to built a complete application for sizing, e.g. by connection of calculation components (for the sizing model), optimisation component and post-processing components.

Notes: Purpose - Seeks to determine the optimal shape design of an induction heating device. Design/methodology/approach - Presents, through a case study, the optimal shape design of a multiple coil inductor for surface heating. Resorts to a procedure of automated optimal design, based on evolutionary optimisation and processing both continuous-valued and discrete-valued variables. Findings - Demonstrates that it is possible to solve the design problem routinely using an optimisation tool (OptiNet) that is built to work seamlessly with a coupled electromagnetic-thermal simulation. Originality/value - Every design criterion that is likely to be of interest to a designer of industrial applications can be described to the system and optimised in a reasonable time frame.

Notes: Purpose - Aims to present recent activities in experimental investigations and numerical modelling of the induction cold crucible installation. Design/methodology/approach - Temperature and velocity measurements using thermocouples and electromagnetic velocity probes were performed in aluminium melt which was used as a model melt. Measured temperature field and flow pattern were compared with transient 3D calculations based on large eddy simulation (LES) turbulence modelling scheme. Numerical results are in good coincidence with the experimental data. Findings - The modelling results show that only 3D transient LES is able to model correctly these heat and mass transfer processes. Originality/value - It is revealed that transient 3D modelling provides a universal tool for simulating convective heat and mass transfer processes in the entire melt influenced by large scale instabilities in the recirculating flows, which contain several main vortexes of the mean flow.

Notes: Purpose - To use an experimentally calibrated turbulent flow model to determine whether two- and three-phase electromagnetic stirrers provide equivalent stirring when continuously casting steel billets and blooms. Design/methodology/approach - The results obtained in this paper were obtained by using a 3D quasistatic electromagnetic model to obtain the Lorentz forces that act on the liquid steel. A computationally efficient method was used to account for the effect of the conducting fluid motion on the forces. A 3D turbulent flow model that incorporated Reynolds stresses and high order upwinding was used to predict the fluid flow. The model has been calibrated using the experimental data. Findings - The paper shows that for square and rectangular cross section casting moulds, having inside dimensions of 140?×?140?mm and 140?×?196?mm, respectively, a two-phase electromagnetic stirrer consistently produces stirring velocities that are 12-15 percent below those produced by an equivalent three-phase design. Research limitations/implications - The impact on the fluid entering the casting mould through the submerged nozzle has been neglected. The model should be further developed to consider this important factor. Practical implications - A two-phase stirrer is much more compact than the equivalent three-phase design, and since space is at a premium in the vicinity of the casting mould, being able to use a compact design is desirable. The two-phase design was long believed to produce inferior stirring due to the negative impact of electromagnetic space harmonics. This paper shows that for the range of mould dimensions considered in the paper, there is a good trade-off between the compact two-phase design and the slightly lower stirring velocities that result. Originality/value - The paper presents the first quantitative comparison between two- and three-phase electromagnetic stirrers that illustrates, in a practical sense, the stirring effectiveness of each approach. The paper will be of value to users of this equipment.