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  • Articles  (3,769)
  • Wiley-Blackwell  (3,326)
  • Emerald  (443)
  • American Association for the Advancement of Science (AAAS)
  • American Association of Petroleum Geologists (AAPG)
  • 1995-1999  (2,886)
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  • Electrical Engineering, Measurement and Control Technology  (810)
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  • Articles  (3,769)
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  • 1
    Electronic Resource
    Electronic Resource
    Bradford : Emerald
    Sensor review 19 (1999), S. 273-277 
    ISSN: 0260-2288
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Despite many advances during the last decade in both infra-red sensor and solid state camera technology, until now little headway has been made in the production of cost-effective semiconductor sensor arrays capable of operating far into the infra-red. Old ideas, renewed by the capabilities offered by the latest micromachine technology, may change all this. Reviews the problems associated with building such sensor arrays before introducing some interesting new research results.
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  • 2
    Electronic Resource
    Electronic Resource
    Bradford : Emerald
    Sensor review 19 (1999), S. 285-291 
    ISSN: 0260-2288
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: The requirement to quickly obtain 3D measurements is common to a variety of tasks in different fields of applications, i.e. robotics, space craft rendezvous and docking scenarios and industrial assemblies. In this paper, a novel type of non-scanning optical 3D laser camera is presented. This is useful for both space and industrial applications. Avoiding any moving mechanical parts, the new sensor is able to exceed the frame rate and lateral resolution limits of common scanning devices, while providing both a grey-scale image and a dense range image of the scene at the same time.
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  • 3
    ISSN: 0260-2288
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Laser interferometry-based sensing (LIS) technique has been proposed and established recently to track and perform dynamic measurements on a moving end-effector of a robot manipulator. In this paper, a technique using LIS system to perform guidance of a manipulator is proposed. The LIS system is used as a sensor to guide the end-effector of a robot manipulator. This is to be accomplished through the implementation of guidance error determination and compensation, and path generation in the control algorithm. This technique can be used to accurately guide the manipulator's end-effector to a specified location or along a specified path with a high level of accuracy. The structure and various components within the system and the control strategy are also presented.
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  • 4
    Electronic Resource
    Electronic Resource
    Bradford : Emerald
    Sensor review 19 (1999), S. 300-305 
    ISSN: 0260-2288
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Polymer-carbon black composites are a new class of chemical detecting sensors used in electronic noses. These composites are prepared by mixing carbon black and polymer in an appropriate solvent. The mixture is deposited on a substrate between two metal electrodes, whereby the solvent evaporates leaving a composite film. Arrays of these chemiresistors, made from a chemically diverse number of polymers and carbon black, swell reversibly, inducing a resistance change on exposure to chemical vapors. These arrays generate a pattern that is a unique fingerprint for the vapor being detected. With the aid of algorithms these patterns are processed and recognized. These arrays can detect and discriminate between a large number of chemical vapors.
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  • 5
    Electronic Resource
    Electronic Resource
    Bradford : Emerald
    Sensor review 19 (1999), S. 195-202 
    ISSN: 0260-2288
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: A binaural sonar sensor for blind persons which models the bat sonar is described. System performance with field plots are presented along with signal analysis on objects forming targets. The distal spatial resolution is little more than one wavelength at the lowest frequency of 50 kHz. The operating bandwidth is 50 kHz producing the power to discriminate between objects. Distance and direction information is obtained over a field of view of 50 degrees within one frequency sweep. Blind persons have demonstrated mobility akin to sighted mobility. This knowledge is of value in designing robots.
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  • 6
    Electronic Resource
    Electronic Resource
    Bradford : Emerald
    Sensor review 19 (1999), S. 202-206 
    ISSN: 0260-2288
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Continuous Transmission Frequency Modulated (CTFM) ultrasonic sensors can be used to recognise plants. The echo from a plant is modelled as an acoustic density profile. Classification based on features extracted from the echo is more robust than classification based on the echo. Potential applications for this sensing system include landmark navigation and plant sensing for selective spraying of agricultural chemicals.
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  • 7
    Electronic Resource
    Electronic Resource
    Bradford : Emerald
    Sensor review 19 (1999), S. 207-213 
    ISSN: 0260-2288
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: This paper describes the principles of the a.c. field measurement technique, a non-contacting electromagnetic method of crack detection and sizing in metals. The development of the technique is covered, followed by examples of some of the many different applications the technique has been used for, including multi-sensor arrays for rapid manual inspection or for deployment by robotic manipulator in hazardous environments. Finally, recent work on replacing the normal multi-turn coil magnetic field sensors with newly available GMR sensors is discussed.
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  • 8
    Electronic Resource
    Electronic Resource
    Bradford : Emerald
    Sensor review 19 (1999), S. 214-221 
    ISSN: 0260-2288
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: A new approach to rejecting interference between sonar systems is presented in this paper. The approach is based on identifying a transmitter by sending a double pulse with known separation. Using simple delayed pulse subtraction, a sonar receiver can test echo pulses quickly and simply for acceptance. This approach is implemented on a sonar system that is capable of accurately tracking objects at measurement rates exceeding 10 Hz. Two sonar sensors, each consisting of a transmitter and two receivers, are independently controlled to track objects from bearing and range measurements. Matched filtering is used to optimally estimate echo arrival times from which range and bearing angle are derived. Bearing accuracy is typically better than 0.1 degrees but degrades if there is air turbulence and temperature gradients. Bearing errors are shown experimentally to have significant autocorrelation at times of the order of seconds. The ability to reliably reject interference is demonstrated experimentally by both sensors simultaneously tracking the same plane object.
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  • 9
    Electronic Resource
    Electronic Resource
    Bradford : Emerald
    Sensor review 19 (1999), S. 265-267 
    ISSN: 0260-2288
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: A robust and non-intrusive focus control system for laser welding has been developed under a collaboration between GSI Lumonics (Rugby) and Heriot-Watt University in Edinburgh, as part of the Laser Engineering for Manufacturing Applications Programme (LEMA), funded by EPSRC. It uses the light generated by the process, together with the chromatic aberrations of the focusing optics to determine the focal position of the laser relative to the workpiece. Successful closed loop operation has been demonstrated over a wide range of welding conditions, including different materials and laser powers.
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  • 10
    Electronic Resource
    Electronic Resource
    Bradford : Emerald
    Sensor review 19 (1999), S. 278-284 
    ISSN: 0260-2288
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: The advantages of lasers over broad-band light sources for spectroscopic measurements have long been recognized. Laser techniques offer the ability to measure the concentrations of trace species in a gas stream in "real time" with sensitivity and molecular selectivity not possible with broad band spectroscopic techniques. Until recently, the use of laser-based instruments has been largely limited to laboratory or one-of-a-kind devices. However, the increased availability of solid-state tunable diode lasers, recent advancements in fiber optic coupling and advanced signal processing have made it possible to develop instruments that offer customers enabling technology at an affordable price. Spectrum Diagnostix has developed a family of tunable diode laser-based instruments used in a variety of applications including: fugitive release detection of HF and H2S in the refining and petrochemical industries, stack monitoring, and using extractive sample probe, in situ process control. SpectraScan instruments obtain their high sensitivity and chemical selectivity utilizing a technique known as wavelength modulated spectroscopy. Described simply, a near infra-red diode laser's wavelength is scanned rapidly and repeatedly through a molecular absorption line. A photodetector senses the instantaneous fraction of emitted laser power that is transmitted through the chemical bearing gas. Measurement of the relative amplitudes of offline to online transmission yields a precise value of the quantity of chemical along the laser beam's path. The amplitude modulated signals are then detected using established radio receiver and signal processing techniques. The SpectraScan monitors are designed for permanent installation in harsh industrial and petrochemical environments and are approved for Class I, Division 2 hazardous area use. Describes the SpectraScan instruments, their field applications, and reviews operating data compiled from open path measurements of HF in refineries.
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  • 11
    Electronic Resource
    Electronic Resource
    Bradford : Emerald
    Sensor review 19 (1999), S. 268-272 
    ISSN: 0260-2288
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Describes the application of an ultrasonic sensing system for the non-destructive inspection of welds as an alternative to X-rays. Replacing radiography with ultrasound not only allows faster, more economical inspections but also eliminates the health and safety risks associated with radiography. In practical terms that means there is no need to evacuate the site for inspection purposes - construction work can continue, round the clock if necessary, thus dramatically reducing construction times.
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  • 12
    Electronic Resource
    Electronic Resource
    Bradford : Emerald
    Sensor review 19 (1999), S. 260-265 
    ISSN: 0260-2288
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Increased worldwide competition has driven industry to find ever faster and more accurate techniques for product inspection. Although developed only recently, noncontact laser gauging systems (NCLGSs) are quickly becoming an accepted technology for manufacturing, in particular for large volume producers of wire who require online diameter measurement. This paper describes the major components of an NCLGS and how its technology enables manufacturers to incorporate extremely accurate online product measurement. The paper also describes the benefits and issues for concern associated with use of this new technology.
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  • 13
    Electronic Resource
    Electronic Resource
    Bradford : Emerald
    Sensor review 19 (1999), S. 6-8 
    ISSN: 0260-2288
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Discusses the demise of the thermeonic valve and the firm establishment of the transistor as the major active component in electronic circuits.
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  • 14
    Electronic Resource
    Electronic Resource
    Bradford : Emerald
    Sensor review 19 (1999), S. 19-26 
    ISSN: 0260-2288
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Compares the relative merits of CCD and CMOS based video cameras. Describes the design and fabrication of CMOS sensors which include considerable hardware computational elements on the same chip as the sensor array. These enable the device to output picture information in a form that is directly compatible with multimedia PC application requirements.
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  • 15
    Electronic Resource
    Electronic Resource
    Bradford : Emerald
    Sensor review 19 (1999), S. 27-30 
    ISSN: 0260-2288
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Biometrics, the use of various means to identify, or verify the identity of, individuals can be a valuable aid wherever there is a need to control access, whether to a secure site or to an ATM or a piece of sensitive plant or machinery. The Association for Biometrics and the Department of Trade and Industry held a conference last October reviewing Government applications for this family of technologies, including identification of petty criminals in a crowd, speeding the admission of prison visitors and cutting out the queues at airport immigration desks. In support of these and other applications a wide array of techniques is being developed.
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  • 16
    Electronic Resource
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    Bradford : Emerald
    Sensor review 19 (1999), S. 31-32 
    ISSN: 0260-2288
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: This article reports on the 4th International Micromachine Symposium and Exhibition Micromachine (1998) which were held in Tokyo, 28-30 October 1998 and also serves as a supplementary information to the article "Micro sensor developments in Japan" in this special "Micro sensors" issue of the journal. The symposium and exhibition are the annual showcase of the current status of the "Micromachine technology" project which is sponsored by the Japanese Government. Unlike efforts in other countries the Japanese approach is unique in trying to achieve real workable micromachines by establishing micro mechatronics technology. It differs from, for instance, the American MEMS where research is heavily dependent on silicon processing technology to fabricate micro devices on chips. Various kinds of micro sensors are now under development. These initiatives are well worth watching.
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  • 17
    Electronic Resource
    Electronic Resource
    Bradford : Emerald
    Sensor review 19 (1999), S. 33-36 
    ISSN: 0260-2288
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Screen printing is a traditional low cost technique for production of electronic circuitry. Conventionally, screen printing is capable of no smaller than 200-250 micron line and space (500 micron pitch) geometry in anything other than low volume production. In recent years, ERA has been developing a novel approach to screen printing which circumvents the problems with a traditional mesh screen and thereby allows dimensions down to 50 micron line and space to be printed consistently. A major European Commission sponsored project - HIDENIMP - has just commenced with the objective of transferring this manufacturing technology to European industry across a broad range of applications. These include microwave devices (where control of edge definition and gap is important), displays (where minimising track width enhances appearance), precision resistors (where the more controlled deposition characteristics of the µ-Screen can be used and trimming minimised) and environmental sensors.
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  • 18
    Electronic Resource
    Electronic Resource
    Bradford : Emerald
    Sensor review 19 (1999), S. 37-42 
    ISSN: 0260-2288
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: This paper describes some aspects of micro sensors developed as part of the micromachine project in Japan. This national R&D project, industrial science and technology frontier program "Micromachine technology", was inaugurated in 1991 as a ten-year project. The R&D goal is to establish technologies to realize micromachines for the following practical applications; maintenance and repair of power plant facilities; miniaturization of manufacturing facilities; medical diagnosis and treatment. As a result, various types of micro sensors have been successfully developed.
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  • 19
    Electronic Resource
    Electronic Resource
    Bradford : Emerald
    Sensor review 19 (1999), S. 43-45 
    ISSN: 0260-2288
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Many new micromachined angular rate sensors (gyroscopes) are now commercially available. Their rapid development has been mainly due to the automotive industry. A wide range of different devices exists and their performance is significantly improving every year while costs are falling. Much effort is now under way for large volume production. This article provides a general overview of gyroscopic sensors and also describes a novel micromachined rotating device.
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  • 20
    Electronic Resource
    Electronic Resource
    Bradford : Emerald
    Sensor review 19 (1999), S. 46-51 
    ISSN: 0260-2288
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Analyses some of the main ways in which microporous membranes can play a role in the efficient functioning of sensors. These devices are used to detect a property of, or component in, a fluid in contact with the sensor. As used in this article, the term "sensor" is intended to cover the broadest range of optical, optoelectronic or electronic devices used to detect a component of a fluid in contact with the sensor as part of a detection system.
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  • 21
    Electronic Resource
    Electronic Resource
    Bradford : Emerald
    Sensor review 19 (1999), S. 96-105 
    ISSN: 0260-2288
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: While the transference of charge is an essential aspect of every capacitance sensor, a relatively new form of sensor makes overt use of the principle of charge conservation first deduced by Watson in the 1740s. Updated to use a microcontroller, mosfet switches, fet-input opamps and band gap references, the principle of charge transference can be used to create an extremely sensitive and stable device with unique properties that transcend those of more pedestrian capacitance sensors. Also known as "QT" sensors, charge transfer sensors can have a dynamic range spanning many decades with noise floors in the sub-femtofarad regime, allowing differential resolutions of mere fractions of a femtofarad. Such sensors are proving to have unique applications considered heretofore impossible, while also proving themselves as replacements for much more expensive sensing systems using photoelectric, acoustic, RF, and optical imaging techniques.
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  • 22
    Electronic Resource
    Electronic Resource
    Bradford : Emerald
    Sensor review 19 (1999), S. 113-115 
    ISSN: 0260-2288
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: High speed image processing is the basis of a unique 3-D measurement system developed by British Aerospace and the City University Optical Metrology Centre. The system can produce 3-D coordinates for over a hundred measured points up to every 1/25th of a second. As a result it can simultaneously measure locations of components during assembly or guide a robot end effector in drilling operations. This work has recently won the 1998 Metrology for World Class Manufacturing Award for Innovative Metrology and a DSP in Action Award for 1998.
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  • 23
    Electronic Resource
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    Bradford : Emerald
    Sensor review 19 (1999), S. 106-112 
    ISSN: 0260-2288
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: This paper describes SHAPE TAPE™, a thin array of fiber optic curvature sensors laminated on a ribbon substrate, arranged to sense bend and twist. The resulting signals are used to build a three dimensional computer model containing six degree of freedom position and orientation information for any location along the ribbon. The tape can be used to derive dynamic or static shape information from objects to which it is attached or scanned over. This is particularly useful where attachment is only partial, since shape tape "knows where it is" relative to a starting location. Measurements can be performed where cameras cannot see, without the use of magnetic fields. Applications include simulation, film animation, computer aided design, robotics, biomechanics, and crash testing.
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  • 24
    Electronic Resource
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    Bradford : Emerald
    Sensor review 19 (1999), S. 116-120 
    ISSN: 0260-2288
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: The government-sponsored Foresight programme, begun four years ago with the aim of bringing together industrial companies with academic and research organisations to improve the competitiveness of the British economy, has now entered a second round of activity focusing on developing its range of tasks. In the area of sensing technology three themes are being taken up for collaboration by Sira during the coming year: industry and the environment; security and observation; and Earth observation. Last November Sira sponsored a conference to introduce these themes and recently Professor Richard Brook, director of Sira, and Anne Burns, technology marketing manager, talked to Jack Hollingum about the way ahead.
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  • 25
    Electronic Resource
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    Bradford : Emerald
    Sensor review 19 (1999), S. 121-127 
    ISSN: 0260-2288
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Until recently there has been a problem integrating safety related sensors and other safety components with software based control systems for process plant and machinery. Marrying effectively, traditional safety components such as emergency stop buttons, gate interlocks, light curtains, pull cords, safety mats, etc. and the traditional safety relay with modern PCs and PLCs offers quite a challenge. Such problems have now been solved by Smartscan Limited, based in Corby, Northants, UK who have developed the Safenet integrated safety control system - an entirely new approach to machine safety. The Safenet system provides a Master Controller which communicates with field based safety components over a two wire data highway which carries the system power, diagnostic information and all safety related data.
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  • 26
    ISSN: 0260-2288
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Atmospheric dependent, gas sensitive resistors seem to be good candidates for detecting critical air pollution levels. Recently, great progress has been made in the development of various sensor types, but less attention seems to be paid to the integration of sensor elements with different characteristics. The aim of this international project is to develop a smart hybrid gas multi-sensor module for environmental applications, i.e. by combining classical thick- and thin-film elements with polymer-film based sensors and also a signal processing ASIC within a single package, which should be useful for all sensor types. The module should enable multi-sensor operation as well, when connected to an intelligent signal-processing unit.
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  • 27
    Electronic Resource
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    Bradford : Emerald
    Sensor review 19 (1999), S. 135-140 
    ISSN: 0260-2288
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: We describe a new approach to intelligent building systems, that utilises an intelligent agent approach to autonomously governing the building environment. We discuss the role of learning in building control systems, and contrast this approach with existing IB solutions. We explain the importance of acquiring information from sensors, rather than relying on pre-programmed models, to determine user needs. We describe how our architecture, consisting of distributed embedded agents, utilises sensory information to learn to perform tasks related to user comfort, energy conservation, safety and monitoring functions. We show how these agents, employing a behaviour-based approach derived from robotics research, are able to continuously learn and adapt to individuals within a building, while always providing a fast, safe response to any situation. Finally, we show how such a system could be used to provide support for older people, or people with disabilities, allowing them greater independence and quality of life.
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  • 28
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    Bradford : Emerald
    Sensor review 19 (1999), S. 187-194 
    ISSN: 0260-2288
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Measurements of the ultrasonic sound speed of thermosetting resins and composites can be used as an in-process cure monitoring technique. Ultrasonic measurements have an advantage over other in-process techniques in that ultrasonic sensors do not make contact with the part (thus leaving no imbedded sensor or witness mark) and can make true bulk measurements of the part. A new commercially available ultrasonic cure monitoring system for the cure monitoring of thermosetting resins and composites has been developed. Advancements in ultrasonic sensor technology enable the self-contained ultrasonic sensor to be easily installed in a mold and maintain good coupling to the part during thermal cycling to 260°C. Data are presented showing the change in ultrasonic sound speed during the compression molding of epoxy prepregs. The data show a good relationship to the electrical resistivity data collected via dielectric cure monitoring. The ultrasonic technique is also applicable to phenolic based materials.
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  • 29
    ISSN: 0260-2288
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: To ensure the reliable monitoring of machining operations, e.g. by lathes, the forces generated during the metal removal process must be detected with the utmost precision. Almost every type of lathe can be straightforwardly monitored for these factors with a force sensor which not only measures forces in three directions but which also incorporates the necessary electronics to amplify the output signals.
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  • 30
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    Bingley : Emerald
    Microelectronics international 16 (1999), S. 6-14 
    ISSN: 1356-5362
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Reports the research and development results on flip chip on FR-4 and ceramics, using anisotropic conductive film (ACF), anisotropic conductive paste (ACP), or eutectic solder with underfill. Several types of ACF and ACP with different types of conductive particles and adhesives were investigated. Simple but high yield procedures for reworking flip chip on board using ACP and ACF were developed. Processes for flip chip on FR-4 and ceramic boards using eutectic solder bumps with underfill were also evaluated. The flip chips were assembled on test vehicles for temperature cycling and high-temperature high-humidity tests. The reliability performance of the three processes (gold bumps with ACF, gold bumps with ACP, and eutectic solder bumps with underfill) is compared.
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  • 31
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    Bingley : Emerald
    Microelectronics international 16 (1999), S. 15-21 
    ISSN: 1356-5362
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Presents the thermo-mechanical modelling of a new type of area array package: the flip chip on polymer stud grid array (PSGA). The objective is to optimise the material and geometrical design of this PSGA package and the flip chip assembly in order to achieve the highest thermal fatigue reliability for the solder joints in this structure. A parameterised non-linear finite element model is used to calculate the inelastic strains induced in the solder joints due to thermal cycling. The techniques of design of experiments (DOE) and response surface modelling (RSM) enhance the parameter sensitivity analysis and optimisation of the PSGA design. After the optimisation of the structure, a very high solder joint fatigue reliability of this flip chip to PSGA package has been achieved.
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  • 32
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    Bingley : Emerald
    Microelectronics international 16 (1999), S. 22-35 
    ISSN: 1356-5362
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: In a plastic BGA package, the glass transition temperature of 170-215°C for bismaleimide triazine (BT) substrate puts an upper ceiling to the usable wire bond temperature. To compensate for the limitation in thermal energy, high frequency thermosonic bonding was proposed and successfully demonstrated for plastic BGA wire bonding. Design of experiment (DOE) and response surface methods (RSM) for process optimisation were used; bonded areas were also analysed using scanning electron microscope (SEM). Of the four major bonding parameters were investigated, ultrasonic power and bond force appeared to be the most important control factor for wire pulls and ball shear force optimisation. The results show that bonding at low temperature is viable with the use of high frequency transducer wire bonder.
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  • 33
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    Bingley : Emerald
    Microelectronics international 16 (1999), S. 36-38 
    ISSN: 1356-5362
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Presents a survey of build-up technologies based on the manufacture of microvia in thin dielectric sheets (〈 100µm) deposited on PWB materials. These technologies will permit the PWB industry to manufacture high density interconnect substrates and answer the routeing requirements of high number I/Os, BGAs and new area array components. Bull Electronics Angers (BEA) has developed an HDI technology where microvias with hole diameters lower than 100µm are mechanically or laser drilled and interconnected lines at pitch down to 200µm are manufactured. In the frame of a European MEDEA project, ATEMAES, the design of an electronic subsystem manufactured by Magnetti Marelli in ceramic thick film technology has been adapted to the design rules of the HDI technology developed by Bull. This is part of an evaluation program for the use of HDI technology for automotive applications.
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  • 34
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    Bingley : Emerald
    Microelectronics international 16 (1999), S. 43-45 
    ISSN: 1356-5362
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: This paper describes failure load analysis to predict the number of fatigue cycles required to cause adhesion failure at the thick film conductor and alumina substrate interface in ball grid array packages (BGAs). This enables prediction of the number of fatigue cycles required to lift the thick film conductor from the alumina substrate. Adhesion strength is determined by the mechanical properties of the thick-film ink bonding mechanisms, geometry and processing conditions. The investigation is intended to increase the understanding of the adhesion properties between the thick-film ink and the substrate in ball grid arrays.
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  • 35
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    Circuit world 25 (1999), S. 38-46 
    ISSN: 0305-6120
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    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: The strain-based flex fatigue of 18 µm thick copper foil is evaluated over a wide range of strain amplitudes. Seven electrodeposited foils, four commercial grades and three experimental foils, and a commercial grade rolled foil are characterized. The fatigue life versus cyclic strain amplitude curve in the high strain amplitude (low cycle) and low strain amplitude (high cycle) regimes is developed for each foil. On the basis of fatigue life (Nf) and fatigue ductility (Df), the low cycle fatigue performance of eight foils is ranked. Universal correlations of Nf and Df with the uniaxial tensile strength are established. Two electrodeposited foils, experimental foil DF 8 in the high strain amplitude regime and commercial foil DF 9 in the low strain amplitude regime, have been shown to display fatigue performance comparable to that of the commercial rolled GR 8 foil.
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  • 36
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    Circuit world 25 (1999), S. 55-58 
    ISSN: 0305-6120
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    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: This paper examines the make-up of the subcontract printed circuit board industry in the UK and identifies the geographical location of manufacturing sites together with the number of employees at these sites. It describes both the subcontract board-producing and assembly sectors. The maps show the position and size of the sites, and these together with a histogram showing the frequency of ranges of employee numbers, provide an understanding of the structure of the industry. Higher density areas which have a greater incidence of PCB manufacturing activity are identified and compared. It is also shown that there is little consistent relationship between the positions of the major system providers and the PCB subcontract industry sites. Concern is expressed about the ability of the many smaller companies to compete in the supply of emerging assembly and substrate technologies.
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  • 37
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    Circuit world 25 (1999), S. 13-17 
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    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Diameter and depth of craters and removing efficiency of the material of RCCR (resin coated copper) used in PCB by a single pulse energy of 355nm YAG laser with a variety of pulse energy, pulse width and defocus have been studied in the paper. It is shown that the ablation rates per pulse are much higher when compared with those at 248nm. The crater diameter increases monotonically with the pulse energy. However, when the pulse energy is very high and the power density is higher than 4.0 × 109W/cm2, the crater depth and removing efficiency decrease with the increase of pulse energy. The pulse width has an important influence on the crater diameter and volume when the pulse width changes from 24ns to 38ns, whereas the influence on the crater depth is little. The influences of defocus on ablation results depend on the power density of laser beam. A certain defocus can make both crater diameter and removing efficiency increase for a relatively high power density. Meanwhile, the thermal effect in the process of 355nm laser ablation of RCCR cannot be neglected.
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  • 38
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    Circuit world 25 (1999), S. 18-22 
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    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: While the interest in alternative metalization processes for the manufacturing of printed wiring boards is extremely keen, the long-term reliability of plated through holes fabricated with these electroless copper alternatives remains in question. However, during the last three years, significant process improvements have been made in the direct metalization process based on a patented dispersion of graphite. This paper will describe the technology in detail and present data on the reliability and versatility of the graphite based direct metalization process.
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  • 39
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    Circuit world 25 (1999), S. 17-21 
    ISSN: 0305-6120
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    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Precision cleaning with solvent systems based on n-propyl bromide (nPB) has become an important component of the circuit board fabrication process. The nPB-based cleaners have proved themselves valuable alternatives to the once popular chlorocarbons and hydrochlorocarbons. These latter solvents have been largely banned or restricted because of toxicological and/or environmental considerations. n-propyl bromide has nearly identical physical and cleaning properties to 1,1,1-trichloroethane (1,1,1-T or TCA), but it has a low Ozone Depletion Potential (ODP) and a low Global Warming Potential (GWP). A growing body of evidence shows that nPB-based solvents are safe, effective and cost-efficient alternatives for precision cleaning applications. New formulations have now been developed specifically for the electronics industry. The first challenge is the efficient removal of ionic residues left by certain types of solder flux. The second challenge is the prevention of tarnish on silver leads used on some circuit boards. Case histories and a discussion of relevant toxicological, environmental and regulatory considerations will be included.
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  • 40
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    Circuit world 25 (1999), S. 25-27 
    ISSN: 0305-6120
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    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: This paper addresses the issues involved in the design of high-density boards for high-density chip scale packages. An analytical model is developed to calculate the number of I/Os accommodated by the printed wiring board. The model is placed under constraints of package area, package I/O pitch, number of lanes per channel, PWB device feature sizes (I/O, via pad, signal traces), number of routing layers on board and the partition of routing regions on each level. The model is utilized to study the precise impact of number of routing layers and device feature size on the I/O density of PCB. The scheme for optimally partitioning each layer to achieve maximum I/O density is discussed. Specific guidelines are provided pertaining to the usage of higher board layers and/or reduced device feature sizes to design high-density boards for future electronic products.
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  • 41
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    Compel 18 (1999), S. 120-131 
    ISSN: 0332-1649
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    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: In this paper a prototype actuator designed for a high bandwidth servo system is modeled and analyzed using finite elements. Natural frequencies and mode shapes of frequencies below 10kHz are extracted using frequency analysis and compared with the results from an experimental model analysis. The effects of key parameters used in the analysis on the natural frequencies are investigated. The frequency response is calculated using the natural frequencies and mode shapes. The calculated frequency response is compared with experimental results. The comparison of results shows that the numerical results are accurate. From the analysis the mechanical dynamics of the actuator can be understood and characterized. The analysis of the actuator shows that dynamic analysis using finite element modeling is accurate and effective and can be applied to other mechatronic systems.
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  • 42
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    Compel 18 (1999), S. 175-186 
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    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: We introduce the drift-diffusion model with appropriate jump conditions at the junction of the MODFET transistor (AlGaAs/GaAs). We propose a quasi-variational inequality (QVI) model for this device. We assume that the electron density is bounded and piecewise constant. These hypotheses imply that the Poisson's equation becomes linear with respect to the electrostatic potential. The QVI model keeps a coupling with the continuity equation. Free boundaries arise in the medium AlGaAs near the Schottky-gate contact and in the high mobility medium (GaAs) under the effect of the electron affinity discontinuity at the junction. Numerical results of the QVI model show their location versus the applied gate voltage V/up〉 and the molar fraction X of the AlXGa(1-X)As medium. The inequality seems to be a reasonable simplification of the non-linear Poisson's equation.
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  • 43
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    Compel 18 (1999), S. 236-249 
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    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Ventricular surface activation time maps are estimated from simulated and measured body surface potential (BSP) maps and extra-corporal magnetic field maps. In a first step the transfer matrix, relating the primary cardiac sources to the measured potential and/or magnetic field data, is calculated applying the boundary element method. Activation times are determined by minimizing a cost function which is based on this transfer matrix. This optimization method is solved by a quasi Newton method. The critical point theorem is used in order to estimate the starting column matrix.
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  • 44
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    Compel 18 (1999), S. 311-323 
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    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: The new set of standards ISO 10303 "STEP" makes it possible to give a complete representation of a product, using the description language EXPRESS. A part of STEP is devoted to the finite element analysis. This paper presents a brief overview of the architecture and the methodology of STEP and EXPRESS, with special attention to the part concerning the finite element analysis. The possibility to use it in modelling electromagnetic phenomena will be discussed. An example showing the description of a typical problem in electromagnetism will be implemented using EXPRESS.
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  • 45
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    Compel 18 (1999), S. 469-482 
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    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: The paper describes an efficient method to extract the B-H nonlinear characteristic from the experimental flux-current F-I data obtained using a non-uniform magnetic field device. Both functions are monotonically piecewise linear approximated with the same number of breakpoints. The method was successfully applied to characterize the ribbon core material of a fluxset magnetic field sector. In this case the hysteresis loop and the lumped magnetic circuit were extracted. Comparison with experimental results validates the proposed method.
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  • 46
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    Compel 18 (1999), S. 398-409 
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    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: In this paper, a hybrid formulation for solving time harmonic eddy current problems in terms of magnetic field h is considered. In particular, we discuss some properties of the implicit boundary condition on the discrete level and the computation of the integral operator exploited in this context. An iterative technique is confirmed to be efficient in solving the arising, partly dense, complex linear system of equations. Furthermore, some test results, including timings for linear solvers are presented.
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  • 47
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    Compel 18 (1999), S. 436-444 
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    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Fluxset type eddy current probes are used for detecting discontinuities in conducting materials. The measurements obtained by such probes can be used for the reconstruction of the parameters of the detected discontinuity if the output signal of the measurement is uniquely related to the measured field. In this paper a calibration method is presented for the establishment of the relation between the measured magnetic field and the output signal of the probe. The relation is obtained by the optimisation of the parameters of the mapping between the calculated magnetic field distribution and the measured output signal. The magnetic field distribution due to the interaction of the probe and an infinitesimally thin crack located in a conducting plate is calculated numerically by the solution of a boundary integral equation.
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    Compel 18 (1999), S. 458-468 
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    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: The implementation of a vector Preisach model for the modelling of anisotropic hysteretic soft magnetic materials is outlined. Some comparisons with measurements on alternate and rotational magnetic field excitations are shown. The hysteresis model is inserted inside a two-dimensional finite element solver formulated in terms of magnetic vector potential and nonlinear solution is handled by means of the fixed point method with H-scheme. Results obtained on a two-dimensional geometry are described and discussed.
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    Notes: To circumvent the high computational costs of modelling each lamination to compute the eddy current distribution in three dimensions in conducting laminations, a simple method has been developed. The laminar nature of the eddy currents due to the magnetic leakage field has been considered by applying an anisotropic conductivity with zero or very low value in the direction normal to the laminations. This yields an overall field distribution serving as basis. In a second step, the much smaller eddy current loops caused by the main magnetic flux parallel to the laminations have been taken into consideration by a one-dimensional analytical model. Nonlinearity is neglected.
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    Compel 18 (1999), S. 504-514 
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    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: A new method for the numerical computation of the dynamic behaviour of electro-dynamic loudspeakers is presented. The numerical scheme, based on the finite element method (FEM), allows the simulation of coupled magnetic, mechanical and acoustic fields. The obtained simulation results are in good agreement with measured data.
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    Compel 18 (1999), S. 275-284 
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    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: The identification of magnetic field profiles is crucial in many applications where a direct measurement is difficult. We discuss here a technique, based on the injection of charged particles in the region under examination, which promises to be an innovative and effective tool in the analysis of 1-D field profiles in high current plasma discharges. After the decription of the inverse problem related to the field construction, we consider a suitable discrete identification scheme, and analyze some properties of the latter. The field map in the interest region is reconstructed via a minimization procedure, which identifies the coefficient of a well-suited expansion for the field. In particular, we discuss the precision and robustness of the identification procedure, with respect to the chosen optimization scheme, the amount of data, the order in the field expansion, and the influence of noise on the data.
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  • 52
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    Notes: Finite element discretizations of low-frequency, time-harmonic magnetic problems lead to sparse, complex symmetric systems of linear equations. The question arises which Krylov subspace methods are appropriate to solve such systems. The quasi minimal residual method combines a constant amount of work and storage per iteration step with a smooth convergence history. These advantages are obtained by building a quasi minimal residual approach on top of a Lanczos process to construct the search space. Solving the complex systems by transforming them to equivalent real ones of double dimension has to be avoided as such real systems have spectra that are less favourable for the convergence of Krylov-based methods. Numerical experiments are performed on electromagnetic engineering problems to compare the quasi minimal residual method to the bi-conjugate gradient method and the generalized minimal residual method.
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  • 53
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    Compel 18 (1999), S. 570-586 
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    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Deals with the problem of the electromagnetic torque calculation in the case of either nonuniformity of the air-gap or eccentricity of the rotor. The electromagnetic field distributions have been evaluated for drag-cup motors. An analytical model has been introduced for linear motor based on the variation method for magnetic flux density magnitudes. The total torque and its components have been evaluated for the motors chosen. The decrease of the electromagnetic torque and increase of eddy-current losses have been discussed due to either rotor circular asymmetry or its eccentricity.
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  • 54
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    Circuit world 25 (1999), S. 30-37 
    ISSN: 0305-6120
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    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: A novel tin electrodeposition chemistry and process has been developed at Bell Laboratories, Lucent Technologies, New Jersey, USA. This process produces smooth, satin bright tin deposits which have stable, large grain structures. The deposits contain very low organic content and, as a consequence, exhibit excellent ductility, solderability and reflowability. The chemistry is capable of operating at elevated temperatures over a wide range of current densities, and is, thus, applicable to rack, barrel and reel-to-reel operations. All chemical components, including breakdown products are fully analyzable with conventional analytical methods. Extensive bath life studies show that the deposit appearance and material properties, including grain structures, are stable in relation to the age of the electroplating chemistry. In addition, the grain refiners used are highly stable, and have few breakdown products as the chemistry ages. All these features imply a robust process which has been confirmed in various manufacturing environments. This tin electroplating process has been utilized in plating coatings for connectors, solder bumps, PWBs and components for semiconductor applications.
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    Circuit world 25 (1999), S. 18-26 
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    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Multi-layer surface finish, from the bottom to top, of electroless Ni, electroless Pd, and immersion Au (Ni/Pd/Au) have been introduced in the printed circuit board (PCB) industry recently. This paper reports an evaluation of this surface finish from the perspective of solder joint attachment reliability, especially to see if the Ni/Pd/Au could be immune from the brittle interfacial fracture of PBGA on electroless Ni/immersion Au, recently observed and reported by us. PCBs with Ni/Pd/Au finishes, made from two vendors with varied Pd layer thickness were attached with PBGA packages, and tested in four-point bending. When joint strength is strong, bending tests resulted in peeling off the PCB pads; otherwise, brittle fractures occurred at the interface between solder balls and PCB pads. After aging, solder joints on all Ni/Pd/Au and reference metal finishes failed by the same brittle fracture at the interface between Ni-Sn and Au-Sn intermetallic compounds. It is concluded that the interfacial fracture was controlled by something other than the Pd, and the existence of the Pd did not prevent the interfacial fracture. Also, the presence of Pd could not prevent the Au migration and subsequent fracture.
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    Circuit world 25 (1999), S. 41-48 
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    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: A family of cavity-down plastic ball grid array (PBGA) packages have been designed by split via connection (SVC) and split wrap around (SWA) methods. Because of the special designs, these packages consist of a single core of organic material and two-metal layers of copper and are manufactured with the conventional printed circuit board (PCB) process at very low cost. The electrical performances of the packages are studied by both numerical simulations and experimental measurements. Parasitic parameters are extracted from time domain reflectometer (TDR) and time domain transmission (TDT) measurements. Cross-talk and simultaneous switch output (SSO) noise of the packages are also investigated.
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    Circuit world 25 (1999), S. 35-40 
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    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: This paper explores the capability of electroless copper deposition plus acid copper electroplating to metallize high aspect ratio microvias.
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    Circuit world 25 (1999), S. 23-27 
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    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Palladium surface finishes are utilized on leadframes, printed wiring boards and automobile sensors. Their superior functional performance and the considerable environmental impact of plating lead-free finishes for packaging processes have been increasingly recognized by the electronic industry. Wire bondable and solderable palladium finishes meet military and industrial standards at no extra cost in the overall assembly processes when compared to traditional packaging techniques. In addition to the development of palladium plating chemistries and technologies, the functional properties of the surface finishes including their wire bonding performance have also been investigated at Bell Laboratories. In this study, gold and aluminum wire bonding to palladium finishes was tested and the wire bond pull force and break position were examined in order to optimize the bonding processes. The results of the study are reported in this paper.
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    Circuit world 25 (1999), S. 22-24 
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    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: This paper explores the use of models of substrate behaviour to examine the wireability constraints on PCBs due to signal layers and buried and through vias. The importance of product scale as a factor affecting technology choice is examined in detail, and the factors that decide the need for multi-layer construction and buried and through vias are discussed. Large PCB layouts are constrained by lack of space for traces - trace bound; a limitation that can be removed by using multi-layers and through hole vias. Small PCB layouts are constrained by lack of space for vias - via bound; buried vias and landless vias are particularly useful for maximising wiring density under these conditions. A further observation is that the use of multiple layers offers diminishing returns as each further layer is added. For small high wiring density PCBs approximately four layers supporting blind vias can give excellent support for the use of high I/O (Input/Output) density packages.
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    Compel 18 (1999), S. 43-60 
    ISSN: 0332-1649
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    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: In this paper we present a new autoregressive (AR) method for bispectrum estimation defined in terms of its third-moment sequence. The method is based on the segmentation of data into coupled records, and can be considered to be a modification of the "third order recursion method"(TOR). Its foundation resides in considering the data of the process at the left and the right of each record (needed for the calculation of third moment sequence) as not null and taking them as the data corresponding to the preceding and succeeding record respectively. Several simulated examples show that this method allows model parameters to be obtained with greater precision, most of all when only few data are available per record. The influence of factors such as number of data and records, model order, and added white and coloured Gaussian noise on the parameters' estimation is also considered.
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    Compel 18 (1999), S. 103-119 
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    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: There are two conflicting views about electromagnetic phenomena. The first is based on the action between stationary and moving particles of electric charge and the second on energy distributions in electric and magnetic fields. The difference between these approaches is seen most clearly in the roles assigned to the potentials. According to the particle view the potentials convey the force from one particle to another, whereas in the field approach the potentials are system parameters related to the field energy. The article compares the two views and concludes that the particle view faces impossible difficulties because it ascribes local significance to quantities which are unobservable and conflicts with the quantum-mechanical understanding of charge as a statistical distribution.
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    Compel 18 (1999), S. 165-174 
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    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Some improvements are made for Fast Boundary Tracking algorithm according to the practice of the electric machine design in the paper. As discrete variables play a dominant role in determining the values of the objective function and the constraint functions in the motor optimal design, the algorithm is improved in the paper. From the algorithm, a software is developed and used for the optimal design of the induction motors of Y series. The results show that the algorithm is reliable and efficient.
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    Compel 18 (1999), S. 204-214 
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    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: In this paper an outline of the development of methods for the analysis of non-linear circuits is presented. Non-inert and inert elements have been discerned and an inertia measure has been proposed. For this purpose, an exponential function with time constant T equal to TR, TL, or TC is formulated for an element of type R, L, or C, respectively. In circuits with the imposed cause, which varies sinusoidally in time with period Te, the following situations are distinguished and considered: Te » T; Te « T; and Te ˜ T. In the first case, the effect changes in time according to the non-linear characteristic of the element. In the second case, the respective circuit is referred to as the "quasi-linear", because for the sinusoidal cause the effect is also sinusoidal. In the third case, the hysteresis occurs and the effect is a two-valued function. The hysteresis effect occurs also in resistive elements.
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    Compel 18 (1999), S. 61-76 
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    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: A stationary 3D energy-transport model valid for semiconductor heterostructure devices is derived from a semiclassical Boltznmann equation by the moment method. In addition to the well-known conservation equations, we obtain original interface conditions, which are essential to have a mathematically well-posed problem. An appropriate modelling of the physical parameters appearing in the system of equations is proposed for gallium arsenide. The model being written and its particularities mentioned, we present a novel numerical algorithm to solve it. The discretization of the equations is achieved by means of standard and mixed finite element methods. We apply the model and numerical algorithm to simulate a 2D AlGaAs/GaAs MODFET. Comparisons between expenrimental measurements and calculations are carried out. The influence of the modelling of the physical parameters, especially the electron mobility and the energy relaxation time, is noted. The results show the satisfactory behaviour of our model and numerical algorithm when applied to GaAs heterostructure devices.
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    Compel 18 (1999), S. 6-37 
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    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: A mathematical gas dynamic model for semiconductor devices is numerically analysed. The well-known ballistic diode problem is taken as an example.
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    Compel 18 (1999), S. 77-83 
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    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: The divergence equations in Maxwell's theory are Gauss law and the statement that magnetic monopoles do not exist; from this point of view these two equations are fundamental. However, from a practical point of view, it is generally believed that Maxwell's divergence equations are redundant and may be ignored provided that they are satisfied at some time t-0. It has been proved recently that this idea is not correct for boundary-initial value problems. To make mathematical arguments more accessible, we analyse here the role of the divergence equations in the framework of 2D-electromagnetism.
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  • 67
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    Compel 18 (1999), S. 132-142 
    ISSN: 0332-1649
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: For each natural n let Fn denote the collection of mappings of Rn onto itself defined by: F ?Fn if and only if there exist n strictly monotone increasing functions fk mapping R onto itself such that for each x =[x1, ..., xn]T ? Rn, F(x) = [f1(x1), ..., fn(xn)]T. The following new property of the class P0 of matices is proved: a real n × n matrix A belongs to P0 if and only if for every G, H ? Fn the set S0 = { x ? Rn : - G(x) =Ax = - H(x) } is bounded. As an illustration of this property a method of estimating the unique solution of the nonlinear equation F(x) + A(x) =b describing the large class of DC transistor circuits is developed. This can improve the efficiency of known computation algorithms. Numerical examples of transistor circuits illustrate in detail how the method works in practice.
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  • 68
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    Compel 18 (1999), S. 187-203 
    ISSN: 0332-1649
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Computer simulations were done extensively in order to study non-linear dynamics of laser-plasma interaction in InSb semiconductor. We constructed the modified Duffing kind of non-linear semiconductor plasma oscillator equation. Collision frequency is found to be dominant parameter to influence the bifurcation, chaos, hysteresis and bistable effects of plasma wave. Small windows of higher period cascade above the critical value of laser parameter (a1a2) in the chaos region are observed. Laser-plasma exhibits too much chaotic regime at lower value of laser driving frequency (d). Hysteresis and bistable regions of plasma wave are presented and the conditions for their occurence are identified. The unstable regions completely merge at higher value of effective collision frequency (?).
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  • 69
    ISSN: 0332-1649
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    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: A boundary element method in terms of the field variables is applied to three-dimensional electromagnetic scattering problems. Especially, the influence of a dipole excited field on low conducting materials situated very close to the antenna will be discussed. We use higher order edge elements of quadilateral shape for the field approximation on curved surfaces. The tangential components of the unknown field variables are interpolated by vector element functions. The Galerkin method is implemented to obtain a set of linear equations. The applicability of the proposed edge element is investigated by the comparison of different BEM-formulations and FEM-results.
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  • 70
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    Compel 18 (1999), S. 515-527 
    ISSN: 0332-1649
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    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: The paper presents an efficient modeling technique for the fluxset magnetic field sensor. Using separate numerical solutions for the electric and magnetic fields, an equivalent SPICE circuit is extracted in the postprocessing phase. The main contribution of the paper is the technique used to model the distributed capacitive effects in insulation between coils, by concentrating them in an "Extended II scheme", an infinite circuit which is optimally reduced to a finite one. The results are in qualitative agreement with the experimental ones.
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  • 71
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    Compel 18 (1999), S. 611-622 
    ISSN: 0332-1649
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    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: The paper deals with a coupled field-circuit simulation of transient and dynamic states in a non-linear axisymmetrical electromagnetic device. The mathematical model of the dynamic phenomena includes: an equation of transient electromagnetic field in a non-linear conducting and moving medium, equations of the converter electric circuits and the equation of mechanical motion. The numerical implementation of the algorithm is based on the finite element method. The Crank-Nicholson scheme for time discretization has been applied. In order to include nonlinearity, the Newton-Raphson process has been adopted. The influence of the saturation effect on the dynamic characteristics of the device has been investigated.
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  • 72
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    Compel 18 (1999), S. 38-42 
    ISSN: 0332-1649
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: By using the central limit theorem, it is possible to consider the Fourier's transform of a stochastic process with independent increments as a Gaussian random variable of which the mathematical expectation and the variance are respectively integrals of the mean and the variance of this process. One can then use this result to analyze the statistical properties of linear feedback systems in the frequency domain, that is to say in terms of transfer functions. The advantage of this approach is that one can deal with linear systems subject to squared white noises, in a very simple manner.
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  • 73
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    Compel 18 (1999), S. 84-94 
    ISSN: 0332-1649
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    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: This paper describes an efficient reduced-order method for the analysis of cylindrical dielectric resonators with an inhomogeneous dielectric medium. The field equations are formulated using the Laplace-domain finite element method and are reduced to lower-order models using the complex frequency hopping (CFH) technique. CFH is a moment matching technique which has been used successfully in the circuit simulation area for the solution of a large set of ordinary differential equations. The proposed technique is faster than the conventional approach by one to three orders of magnitude. The results are compared with those of other numerical methods available in the literature.
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  • 74
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    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Electrical potentials in a junction field transistor can be calculated using a simplified model based on a complete depletion assumption. This gives rise to a free boundary problem. We show here how we can approximate this problem with a quasi-variational inequality technique and the shape optimization method. A detailed analysis of these methods is presented. Using some numerical experiments we compare our results with the solution of the discrete drift-diffusion system, accomplished with a Gummel-like algorithm. The numerical results suggest that the methods proposed here work successfully and that the shape optimization technique provides a reasonably free boundary without excessive iterations.
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  • 75
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    Compel 18 (1999), S. 215-224 
    ISSN: 0332-1649
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    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: The paper presents an extension to previous work on modelling AC losses in high-temperature superconducting tapes as a highly non-linear diffusion process. Following successful formulation for a bulk superconductor the presence of silver in a tape has now been included, using a "sandwich" model, to represent more realistically the practical arrangement. The results of the extended 1-D model are included and a new 2-D scheme is described using finite difference formulation. Effects of non-linearity are emphasised.
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  • 76
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    Compel 18 (1999), S. 361-371 
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    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Several second order edge elements have been applied to solving magnetostatic problems. The performances of these elements are compared through an example of magnetic circuit. In order to ensure the compatibility of the system equations and hence the convergence, the current density is represented by the curl of a source field. This avoids an explicit gauge condition which is cumbersome in the case of high order elements.
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  • 77
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    Compel 18 (1999), S. 422-435 
    ISSN: 0332-1649
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    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: In this paper a method is presented for an efficient solution of the direct problem (find the scattered field for a given thin crack and driving field) in the time domain. This is a fundamental step in any non destructive evaluation problem. Two different approaches, one in the time domain and the other based on Fourier analysis, are used and compared with reference to a configuration for which some experimental results are available. The advantages and drawbacks of the two approaches are briefly discussed.
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  • 78
    ISSN: 0305-6120
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    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: While promising significant improvements in the cost and performance of electronic systems, the advent of new area array packaging concepts such as the BGA and newer area array CSPs has placed significant new demands on the substrates used in their interconnection. New methods such as build-up multilayers and micro vias and co-lamination of inner layers have been described and implemented by a number of different firms in an attempt to address this important issue. One such method employs simple double-sided plated through hole flex circuits and the use of conductive pastes and bondplies to provide reliable electrical and mechanical connection between layers during a simple lamination cycle. The process, briefly described herein as a co-laminated multilayer flex, is detailed in terms of both process steps and manufacturing flow. The structure of the interconnection substrate is also modeled and examined to determine its electrical performance potential according to electrical modeling software. Finally, detailed are the performance of the structure in reliability testing and an analysis of the expected design and performance advantages that might be obtained by such type constructions in combination with BGAs and area array CSPs.
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  • 79
    ISSN: 0305-6120
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    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: This paper presents the defects that occur during the assembly and manufacturing of solder joints in single-sided insertion-mount printed wiring boards (PWBs). Each type of defect is discussed, with particular focus on how these defects are related to solderability issues, the mechanisms of failure due to defect-induced failure accelerators, and the effect of the defect on solder joint reliability.
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  • 80
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    Circuit world 25 (1999), S. 8-16 
    ISSN: 0305-6120
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    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: As an alternative to hot air levelling, a fundamentally new surface finish chemistry and process for solderability preservation of printed circuit boards is described: a pretreatment of the copper followed by an optimized formulation of an immersion tin. The precise and reproducible surface finish formation offers reliable solderability, economic and technical advantages for all kinds of PCBs, even for those with the most modern miniaturized structures. The deposition chemistry and ageing properties of the new Organic Metal/tin surface is discussed, based on electrochemical, wet chemical and electron microscopy studies. The results culminate in an almost complete basic understanding of the tin chemistry and the surface finish performance.
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  • 81
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    Compel 18 (1999), S. 285-297 
    ISSN: 0332-1649
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    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: The use of niching genetic algorithms can provide a method of a more widespread search of the design space for a device than more conventional methods. It provides, in effect, a breadth first rather than a depth first search. Thus several alternative designs may be evaluated in parallel.
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  • 82
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    Compel 18 (1999), S. 337-347 
    ISSN: 0332-1649
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    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: This paper discusses the perfectly matched layer method recently proposed for the computation of static or quasistatic fields in open boundaries. In particular it is shown how the method can be derived by means of a particular co-ordinate transformation applied to a finite-size isotropic domain surrounding the system of interest. The method is therefore equivalent to a trivial truncation from the point of view of both accuracy and computing time.
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  • 83
    ISSN: 0332-1649
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    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: In the finite element analysis of electrical machines the multi-conductor winding in a stator slot is usually modeled simply by a single conductor with constant current density. The size of a finite element problem due to the precise modeling of eddy currents in the multi-conductor windings can be much larger compared to the single conductor model. The paper investigates a new FEM approach for the consideration of eddy-currents in multi-conductor windings surrounded by nonlinear media, a case typical in electrical machinery. The method, called elimination of inner nodes, is evaluated in the paper as a possible solution for multi conductor eddy current problems. The paper presents examples and concludes in what circumstances the method of elimination is efficient.
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  • 84
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    Compel 18 (1999), S. 587-599 
    ISSN: 0332-1649
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    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Voltage ranking attempts to rank busbar voltage deviations from their normally accepted security margins based on a set of performance indices (PI), without performing a full load flow. Existing methods suffer from either masking effects or long computation time. In this paper, an artificial neural network method is proposed for voltage ranking. Counterpropagation network (CPN) has been employed to overcome the problems listed above. A variety of input features are used with the aim of lowering the dimension of the proposed ANN to make it applicable for large power systems. The method is tested on two example systems, a five-bus system and a 71-bus system with very encouraging results.
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  • 85
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    Compel 18 (1999), S. 629-637 
    ISSN: 0332-1649
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    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: The standard Newton iteration scheme to solve a non-linear system of equations obtained from the finite element methods is based on the updating of the field dependent element reluctivity. Usually, the manufacturer of the ferromagnetic material provides a BH-characteristic as diagram or in the form of a table of data samples. The influence of the material properties, in particular their accurate numerical representation, is significant for the rate of convergence during the Newton iterations. Here, a numerical optimization aiming at a technically smooth non-linear characteristic is performed to obtain a higher rate of convergence of the Newton iteration scheme.
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  • 86
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    Circuit world 25 (1999), S. 6-24 
    ISSN: 0305-6120
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: An overview has been presented on the topic of alternative surface finishes for package I/Os and circuit board features. Aspects of processability and solder joint reliability were described for the following coatings: baseline hot-dipped, plated, and plated-and-fused 100Sn and Sn-Pb coatings; Ni/Au; Pd, Ni/Pd, and Ni/Pd/Au finishes; and the recently marketed immersion Ag coatings. The Ni/Au coatings appear to provide the all-around best options in terms of solderability protection and wire bondability. Nickel/Pd finishes offer a slightly reduced level of performance in these areas which is most likely due to variable Pd surface conditions. It is necessary to minimize dissolved Au or Pd contents in the solder material to prevent solder joint embrittlement. Ancillary aspects that include thickness measurement techniques; the importance of finish compatibility with conformal coatings and conductive adhesives; and the need for alternative finishes for the processing of non-Pb bearing solders are discussed.
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  • 87
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    Circuit world 25 (1999), S. 47-54 
    ISSN: 0305-6120
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    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Based on the superior properties of the COPNA resin laminate exhibiting Tg at 2558C, small CTE at 5-7 ppm (xy-axis) and at 29 ppm (z-axis), reliability of both two-layered and six-layered printed wiring boards using COPNA resin as a matrix were evaluated. In the case of the two-layered system, it exhibited higher reliability than the FR-4 graded epoxy-resin laminate in the entire tests, and exhibited higher reliability than the BT resin laminate in the THB test, heat-shock test, and heat-cycle test. In the case of the six-layered system, it also exhibited higher reliability than the BT system in both heat-shock test and PC test.
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  • 88
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    Circuit world 25 (1999), S. 6-10 
    ISSN: 0305-6120
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: "A patterned arrangement of printed wiring utilizing flexible base material with or without flexible coverlayers". The balance of this brief article will hopefully serve to help the reader understand this remarkable interconnection technology and appreciate just how widely the technology can be applied.
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  • 89
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    Circuit world 25 (1999), S. 59-64 
    ISSN: 0305-6120
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    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: This paper extends our study of the sequential electrochemical reduction analysis (SERA) technique for evaluation of various alternative finishes and it discusses the application of the SERA technique to assess the surface conditions of the silver finish. The tarnishing products of the silver formed under ambient and artificially created conditions were analyzed, the protective effect of an anti- tarnishing film was evaluated, and the influence of the elevated temperatures (reflow) on the stability of the organic inhibitor and the formation of the tarnishing film will be shown.
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    Circuit world 25 (1999), S. 25-29 
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    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: This paper focuses on the comparative study on reliability performance of various surface coatings. Only brief descriptions of coating processes, material physical properties, costs, and their applications are given.
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    Circuit world 25 (1999), S. 11-17 
    ISSN: 0305-6120
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    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Polymer thick film (PTF) technology provides the lowest cost, cleanest and most efficient manufacturing method for producing flexible circuits. Non-contact radio frequency (RF) smart cards and related information transaction devices, such as RFID tags, appear to be a good fit for PTF-flex. Flip chip also seems well suited for these "contactless" RF transceiver products. Flip chip and PTF adhesive technologies are highly compatible and synergistic. All PTF SMT adhesives assembly methods are viable for flip chip. However, the merging of flip chip with PTF-flex presents major challenges in design, materials and processing. This paper will compare assembly methods and discuss obstacles and solutions for state-of-the-art flip chip on flex within the RFID product environment.
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  • 92
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    Circuit world 25 (1999), S. 31-34 
    ISSN: 0305-6120
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    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Ball grid array (BGA) component packages challenge the circuit board design with signal routing and layout, creating in some cases extra board layers and added vias all resulting in increased costs for the printed circuit board (PCB). As component densities increase and microBGA (µBGA) and other fine pitch components become more common, microvia-in-pad technology will ease the transition to these fine pitch components. This paper presents and profiles a cost-effective solution to interconnecting BGAs on PCBs using laser drilled blind vias connecting the outer three or more layers of a multilayer circuit board. Following a discussion on the design advantages, a comprehensive outline of the PCB fabrication process explores a new procedure for the rapid production of via-in-pad multi-depth blind via laser drilling.
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  • 93
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    Circuit world 25 (1999), S. 27-30 
    ISSN: 0305-6120
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    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Studies immersion gold over electroless nickel, immersion gold over electroless palladium, immersion gold over electroless palladium over electroless nickel, immersion gold over immersion silver and immersion silver. In the palladium finishes, two palladium thicknesses were evaluated: 10-12µin. and 18-20µin. Multiple plating chemistry suppliers provided plated test vehicles. HASL and OSP test vehicles were included as control samples. In total, 14 finishes were evaluated in the test matrix. The test vehicle was a daisy chain of zero ohm 1,206 chip resistors that could be monitored individually. Test vehicles were assembled using 63Sn/37Pb eutectic solder paste on an automated assembly line. The thermal cycle range was -40°C to 125°C with 30-minute transition times and 15 minutes at each extreme in a single chamber air system. For each test matrix cell, 120 zero ohm resistors (40 from three boards) were continuously monitored for electrical failure (〉100ohms). In addition, resistors were sheared from test vehicles and the shear force at failure was recorded. A decrease in shear force did occur with thermal cycling due to crack initiation and growth in the solder joints. Solder joint cracks have also been examined.
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  • 94
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    Circuit world 25 (1999), S. 6-8 
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    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: A defective printed circuit board assembly that exhibited excessive current leakage was examined to determine the responsible failure mechanisms. Observation of the failure site (determined electrically) by optical and electron microscopy revealed an area in the circuit board where debonded fiber bundles bridged a plated-through-hole (PTH) to a copper plane. This phenomenon is highly suggestive of conductive filament formation.
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  • 95
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    Circuit world 25 (1999), S. 28-32 
    ISSN: 0305-6120
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    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: The oil, flux, and solder added to a hot air solder leveling tool creates an emission of oil mist, acidic gases, and solid metal compounds. The oil tends to form into very fine droplets, resulting in exhaust opacity. Diffusion type fiber bed filters are the optimal choice for the removal of oil mist. For optimal filter efficiency the exhaust stream should be cooled. A wet scrubber upstream of the filter will cool the exhaust stream through water evaporation. Additionally, the scrubber will remove acid vapor and coarse solids from the exhaust. The characteristic quality of a coalescing fiber bed filter is its ability to continuously drain liquid. The defining parameter in the service life of a fiber bed filter is the solids in the exhaust stream. These solids can lodge in the fibers and block a portion of the void area, and hence increase the filter pressure drop. In an attempt to extend filter life, a study was conducted for the use of detergents to clean the filter. These studies show that a detergent can extend filter life in the H.A.S.L. application by removing a blocking agent from the filter. Further tests are planned at additional locations to examine the performance at sites that use other ingredient formulations in the flux, oil, and solder.
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  • 96
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    Compel 18 (1999), S. 372-384 
    ISSN: 0332-1649
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: This paper deals with the inverse scattering problem of reconstructing the material properties of perfectly conducting or dielectric cylindrical objects. The material properties are reconstructed from measured far-field scattering data provided by the Electromagnetics Technology Division, AFRL/SNH, 31 Grenier Street, Hanscom AFB, MA 01731-3010. The measured data have to be calibrated for use in our reconstruction algorithm. The inverse scattering problem formulated as unconstrained nonlinear optimization problem is numerically solved using an iterative scheme with a variable calibration factor which will be determined during the optimization process. Numerical examples show the successful application of the method to the measured data.
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  • 97
    ISSN: 0332-1649
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    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Global optimization in electrical engineering using stochastic methods requires usually a large amount of CPU time to locate the optimum, if the objective function is calculated either with the finite element method (FEM) or the boundary element method (BEM). One approach to reduce the number of FEM or BEM calls using neural networks and another one using multiquadric functions have been introduced recently. This paper compares the efficiency of both methods, which are applied to a couple of test problems and the results are discussed.
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  • 98
    ISSN: 0332-1649
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    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: The paper presents a novel method of utilising neural networks for optimisation systems. First, a conventional magnetic circuit model of the device is developed to create a set of sensitivity rules which guide the optimisation. The rules are coded in a knowledge-based neural network. Second, an error network is developed to correct the approximations inherent in the magnetic circuit approach and this combines with the first network to generate realistic outputs. Finally, the error network can be trained on-line with a finite element system. Over time, the network replaces the finite element analysis, thus speeding up the optimisation process.
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  • 99
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    Compel 18 (1999), S. 385-398 
    ISSN: 0332-1649
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    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: Two sets of dual magnetodynamic and magnetostatic finite element formulations taking thin conducting magnetic shells into account are proposed. The abstraction of the thin region from the computational domain is performed by an appropriate treatment of the surface integral terms arising in the weak formulations. Results are presented for two three-dimensional test-problems.
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    Compel 18 (1999), S. 445-457 
    ISSN: 0332-1649
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    Topics: Electrical Engineering, Measurement and Control Technology , Mathematics
    Notes: A fast dynamic hysteresis model is constructed based on the classical Preisach model and a differential equation which delays its input with respect to the actual value to encompass dynamic effects such as eddy currents and domain wall displacement. It is applied to describe the magnetic behaviour of both grain oriented and nonoriented electrical steel sheets. The results of numerical simulations are compared to experiment and power loss prediction is performed.
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