Philips Journal of Research

Published by Elsevier
Online ISSN: 0165-5817
Publications
Article
In order to use pre-operative images during an intervention for navigation, they must be registered to the patient's co-ordinate system in the operating theatre or to an intra-operative image. For the registration to be valid in the case of patient movements, the registration must be updated or the patient movement must be tracked. One problem in this area is the registration of intra-operatively acquired X-ray fluoroscopies with 3D CT images obtained before the intervention as well as motion tracking for this setup. The result can be used to support the placement of pedicle screws in spine surgery or aortic endoprostheses in transfemoral endovascular aneurysm management (TEAM). The different approaches to 2D/3D registration are discussed and a novel voxel-based method is presented: using a small part of the CT image covering only the vertebra of interest, pseudo-projections are computed and the resulting vertebra template is compared to the X-ray projection using a new similarity measure which is called pattern intensity. Application, performance and registration accuracy are discussed and demonstrated by application to images of a TEAM procedure and of a spine phantom.
 
Article
Pay television (pay TV) systems are presented as they are envisaged in the near future when broadcasters will switch over from analogue to digital transmission formats. Special attention is given to the standardization of pay TV systems by the DVB standardization organization. Philips firmly believes in standardization and aims at a high level of commonality at both ends of the transmission channel. This will reduce the price of the equipment, especially the decoders, and also facilitate interaction with studio equipment supplied by other manufacturers. The standardization is all the more important since we are on the verge of the new digital transmission era in which the consumer will be confronted with a wide range of new services.
 
Article
We introduce the transmission system selected for the next generation of North American broadcast television and for high data rate transmission on cable TV systems. We describe key features of the digital vestigial sideband (VSB) modulation and error protection employed in this system, and of the quadrature amplitude modulation (QAM) systems that competed against it for selection. We review the process used to select this system, in addition to the criteria by which the selection was made. We further review the performance of the system under actual field conditions. The 8-VSB terrestrial mode was found to perform better than the existing NTSC broadcasting system. The 16-VSB high data rate cable mode was found to perform essentially error-free at all receiving locations that met Federal Communications Commission (FCC) specifications for carrier-to-noise ratio.
 
Article
For the enhancement of digital subtraction angiography (DSA) images, registration of mask and contrast image prior to subtraction is a pre-requisite. One of the main requirements of this task is that the region-of-interest used for the calculation of the registration parameters should contain the vascular structures of interest. This, however, is also one of the main problems in DSA because the contrasted vascular structures can be regarded as a distortion that makes the images to be compared dissimilar. In this paper we present a comparison between three frequently used similarity measures and histogram-based similarity measures. This reveals the advantages of the latter. The data-driven approach is especially suitable for registration of two images which are identical except for some structures visible in one but not in the other image. Based on an energy similarity measure, a motion vector field is obtained by template matching, which gives a set of homologous landmarks or control points in the mask and contrast image. A point-based registration is performed fitting the parameter of an appropriate transformation for patient motion correction. An affine and an elastic transformation are compared for an abdominal fluoroscopic scene.
 
Article
The technology of magnetoresistive element (MRE) fabrication and integration as well as some experimental results on the performance of anisotropic and giant magnetoresistive elements are discussed. Most emphasis is put on isolated MREs in specially designed test structures, although results on completed heads will also be discussed. Aspects such as output signal level, noise level, distortion and magnetic stability are the performance indicators considered.
 
Article
This paper presents the basic hardware and software architecture of a class of multi-media terminals that are connected to networks which deliver entertainment and home shopping services to consumers. Some important attributes of the multi-media terminal are: simple user input devices (e.g. infrared remote control), real-time interactivity, adherence to international standards for information representation and communication, and support for downloaded applications from service providers. The terminal discussed in this paper is representative of the current offering of the Digital Video Communication Systems (DVS) business unit of Philips. These terminals are the result of close cooperation between research and product divisions of Philips world-wide in the race to compete in the rapidly growing multi-media and communications markets. The current architecture of the terminal reflects the urgency to get to market with a viable solution; therefore the paper gives some indication of future trends for the hardware and software architecture for this class of multi-media terminals.
 
Article
In multimedia applications information is presented in different forms, such as text, picture, audio and video. As the volume of data increases, it is difficult to archive, access and retrieve information. This paper discusses various issues related to retrieving information in different formats. An overview of both existing and evolving approaches will be presented. A general architecture of a multimedia retrieval system and our initial efforts towards building that system will also be given.
 
Article
Various intrinsic and extrinsic parameters that play a role in the preparation of materials for direct bonding are discussed in this paper. The constitution of a material or a wafer can be described on the basis of its shape and its mechanical, chemical and physical surface finish. Subsurface damage is also of importance with respect to direct bonding applications. Different polishing strategies have been evaluated for polishing the surfaces of different materials to a finish suitable for direct bonding. Optical elements can be polished by means of mechanical polishing; refractory metals by means of dedicated mechanical polishing; III–V compounds by means of chemical polishing; semiconductors by means of tribochemical, i.e. chemomechanical polishing; hard materials by means of enhanced tribochemical polishing; noble metals by means of organo-liquid-supported tribochemical polishing; non-noble metals by means of oxidation-stimulated polishing. After such preparative treatments the material or wafer has to be cleaned, using a suitable method. Certain aspects of the bonding phenomenon itself will also be discussed in this paper.
 
Article
This article describes the Philips automatic train timetable information system which enables the user to call up accurate information about train connections between 1200 German cities over the telephone. In contrast to most of the inquiry systems available so far, the caller can talk to our system in unrestricted, natural and fluent speech, very much like talking to a human operator. No instructions are given beforehand.The system consists of four main components: speech recognition, speech understanding, dialogue control, and speech output. They are separated into independent modules and executed sequentially. The speech recogniser creates a word graph from the spoken input. This word graph is then passed to the understanding component which computes the meaning, using an attributed stochastic context-free grammar. A dialogue manager analyses the results and either accesses the database or comes up with another question if necessary.The system has been made available to the general public in an ongoing field test, both to gather speech data and to evaluate its performance.
 
Article
Film quality and crystalline perfection of SOI layers obtained by bonding and etch back silicon-on-insulator (BESOI) technology have been studied. In particular, the various mechanisms of defect generation that contribute to a degradation of the original bulk Si quality in the superficial Si layer of such SOI structures have been investigated. Utilizing transmission x-ray topography combined with transmission electron microscopy (TEM), the critical processing parameters causing defect generation have been identified and the principal mechanisms of dislocation nucleation have been elucidated. Strain compensated bonded SOI wafers have also been evaluated by non-destructive elastic light scattering and optical beam induced current (OBIC) to obtain topographic defect maps of entire SOI wafers. This analytical technique has the capability to comprehensively characterize surface and subsurface morphological features which result from the bonding and thinning processing steps. A comparison of wafer bonding and etch back technology with different etch stop fabrication techniques is presented. In this review, it is demonstrated that the presence of a boron-doped etch stop layer, with its accompanying lattice contraction and strain compensation, represents a key difference in the observed morphological patterns of bonded SOI wafers.
 
Article
The basic mechanism of electron transport in vacuum through insulating structures is discussed. The transport is based on a self-regulating secondary electron emission process. A general description of the transport process is presented. Three methods to model steady-state transport are briefly reviewed. The features are discussed in the light of application in displays. Also, non-steady-state effects and the role of space charge are addressed.
 
Article
This paper develops a Bayesian motion estimation algorithm for motion-compensated temporally recursive filtering of moving low-dose X-ray images (X-ray fluoroscopy). These images often exhibit a very low signal-to-noise ratio. The described motion estimation algorithm is made robust against noise by spatial and temporal regularization. A priori expectations about the spatial and temporal smoothness of the motion vector field are expressed by a generalized Gauss-Markov random field. The advantage of using a generalized Gauss-Markov random field is that, apart from smoothness, it also captures motion edges without requiring an edge detection threshold. The costs of edges are controlled by a single parameter, by means of which the influence of the regularization can be tuned from a median-filter-like behaviour to a linear-filter-like one.
 
Article
For more than thirty years Philips Research has been engaged in direct bonding. A survey is given of how what was first the study of an optical technology gradually changed into the development of special applications in semiconductor technology. Cooperation between workshops with mastered dedicated technologies and research groups with incentives is shown to be indispensable for success. The principles and diversity of direct bonding are briefly described, after which an impression is given of its stimulating impact on Philips' research programme.
 
Article
Direct bonding of organic polymeric materials can be realized when their surfaces are prepared in such a way that they are clean, smooth and susceptible to direct-bonding. In the surface-preparation process, tribo-chemical polishing is an essential step. Polymeric materials such as polymethylmethacrylate (PMMA), polyarylate, polyimide and polycarbonate were bonded either to themselves, to another polymer or to an inorganic material such as silicon or fused silica. The surfacial bond energy of the room temperature bond is surprisingly high: 0.1–0.2 J/m2. Heating strengthens the direct bond; for example, for a bonded PMMA/PMMA wafer pair annealed at the glass-transition temperature of PMMA (105°C), the surfacial bond strength increases to 7.8 J/m2. This indicates that the bonded surfaces are fused and are interlinked by chemical bonds. When polymers are bonded to low-thermal-expansion materials such as Si and fused silica, during annealing treatments, thermal stresses can induce fracturing of the inorganic part of the bonded wafer pair. By limiting the maximum annealing temperature or the size of the bonded area, fracturing can be avoided.
 
Article
The emerging technologies of digital video and high-speed networks are combined together in a set-top box to provide a wide variety of value-added services to consumers. The control software in set-top boxes includes a real-time multi-tasking operating system with extensive multimedia support. Along with digital TV functionality, the control software provides an easy to use functional interface for set-top capabilities, such as MPEG decoding, high-speed broadband network interface, 2-way communications and graphics. An application-level software called the navigator performs basic TV functions and has the ability to download and execute interactive multimedia applications from network servers.
 
Article
In this paper, we describe the transmission standard selected for transmission of digitally compressed television signals over the cable network in Europe. This standard specifies the error correction coding, modulation and framing structures to be used in the transmitted signal. We review the key features of this standard and describe the architecture of one particular receiver implementation that conforms to this standard.
 
Article
In the coming years, the current analog television distribution will be replaced by digital distribution. Standards for digital transmission via satellite and cable have been developed for this purpose, and a standard for digital terrestrial is on its way. In this paper, the technical details of digital terrestrial television broadcasting will be described.
 
Article
In the Zeus display panel, as in other flat-panel cathode ray tubes, the anode voltage is limited to a few kV. The effects of the anode voltage on phosphor screen performance are discussed which include energy conversion loss processes at the phosphor surface and variation of the number of luminescent centres available. Phosphor efficiency saturation has been measured in the range of 1 to 10 kV, using a pulse-width-modulation scheme. The luminance performance at different excitation conditions is predicted and confirmed experimentally.Coulomb degradation of phosphor screens is shown to increase with decreasing anode voltage. Novel ultra-thin and dense anti-degradation coatings have been developed for zinc sulphide phosphors which effectively prevent fast degradation due to chemical surface reactions. In this way a satisfactory solution has been found to obtain in the Zeus display a luminance level about equal to the best conventional tubes.
 
Article
A high voltage is applied to the screen spacer of the Zeus panel to obtain high brightness and long phosphor lifetime. To prevent field emission due to high local field strength, the screen spacer is coated with a resistivity layer and a low secondary-electron-emission layer. Efficiently operating panels have been made with sputtered substoichiometric and stoichiometric silicon nitride films, and with sprayed chromium oxide and silicon nitride particle layers. For the sputtered layers the effect of stoichiometry, sheet resistance and layer thickness on the panel performance is discussed. In the case of the sprayed layers the effect of suspension quality, spray conditions, layer thickness and layer roughness is discussed.
 
Article
Metal-films for precision resistors combine a very low temperature dependence of the electrical resistance with a tolerance of the resistance of only 0.1%. Corrosion resistance and adhesion to the substrate are of major importance. There are different classes of materials being utilised. For low ohmic applications, we use Cu-Ni alloys with a composition of about 65 at. % (atomic percent) of Cu. For this special alloy, the low temperature coefficient of the resistance (TCR) is a stable, intrinsic property. For most alloys, however, annealing is essential to approach the state of zero TCR. This is the case for the NiCrAl alloys, used for the mid-range of resistances and for SiCrN for high ohmic applications. In high ohmic films, metals are often combined with non-metallic substances like oxides or nitrides. Variation of alloy composition, sputtering conditions and annealing procedures are important for obtaining optimum thin-film properties. Important tools for thin-film characterisation are electron microscopy and related techniques together with high-temperature resistance measurement.
 
Article
Easy processing and mechanical flexibility make polymer light-emitting diodes (PLEDs) suitable candidates for large-area display applications. The understanding of the device properties of PLEDs is a key ingredient for further optimization. This article reviews a device model developed at Philips Research that describes the current and light generation of PLEDs as a function of applied voltage. The model is based on experiments carried out on poly(dialkoxy-p-phenylene vinylene) devices. The combination of the experimental results and model calculations have revealed that (1) the hole current is dominated by space-charge effects and a field-dependent mobility, (2) the electron current is strongly reduced by traps, and (3) the recombination process between the injected electrons and holes is of the Langevin-type. These results explain specific device properties of PLEDs such as a bias-dependent and temperature-independent electroluminescence efficiency (photon/carrier) and indicate directions for further improvement of the device performance.
 
Article
Digital tape recording systems show the same trend as hard-disk drives: a large increase of storage density with time. The use of advanced media and highly sensitive thin-film heads with magnetoresistive (MR) readout will increase the storage density dramatically. Key improvements are narrower tracks, more sensitive MR elements attained by applying the giant magnetoresistance effect, high-saturation flux density pole materials, advanced metal powder tape, intimate head-to-tape contact, and accurate tracking. By increasing the number of channels in the multitrack thin-film head, high data rates can be obtained as well. The basics of digital magnetic recording are discussed and a short historical overview is given of the Philips activities on thin-film heads for tape recording. An outlook on future improvements is given.
 
Article
This paper gives an overview of the efforts in the United States to build high-speed networks for the delivery of digital video services to the homes of consumers. It details the obstacles that need to be overcome for digital video service to commence and the various network architectures and technologies that have been, and presently are being considered. The applications are described that will be enabled by such an infrastructure, termed the NII, as are two digital video services oriented market trials — one being conducted by a cable operator and the second by a telephone company.
 
Article
Standardization is essential for successful development of the market for multimedia systems and applications. Due to the novelty of the technologies involved and the fact that the market is as yet very small, but growing fast, the general consensus in industry is that standardization via the formal procedures employed by the existing standards organizations would take too long. The new market opportunities, created by digital audio, video and multimedia systems and applications, have made it possible to organize specification projects in a phase preceding formal standardization. In these specification projects many industry players are taking part with some of their best engineers and managers as delegates. Two clearly visible examples of these projects are the Digital Video Broadcasting project in Europe and the Digital Audio-Visual Council with a global approach. In this article a short description of the projects, the goals and the methods is given.
 
Article
Polymer light-emitting diodes have become feasible when suitable materials were available. The various relevant properties are interrelated parameters. The solubility can be improved in various ways but here the introduction of side-chains has been found most successful. Colour tuning is achieved by attaching electron withdrawing or donating side-chains. Some polymer defects in PPV are shown. Special functionalities can be built-in. As an example a self-doped PPV is given.
 
Article
This article describes why and how a research program to realize the ‘picture on the wall’ was started in the Philips Research Laboratories some seven years ago. The objective was to maintain the performance advantages of the cathode ray tube (CRT) while realizing a small depth and a low weight of the display. This is accomplished by using electrons in vacuum impinging at high energy on cathodoluminescent phosphors. Insulating internal supports to withstand the atmospheric pressure are required to make the display thin and light. A radical solution was discovered which led to a display with a thickness of about 1 cm for any display size and which is capable of producing CRT quality TV pictures.
 
Article
It is shown that the overall performance of Zeus displays is quite good, as illustrated by photographs of operating panels displaying ‘CRT-quality’ TV pictures. Results of measurements of all relevant performance parameters are presented, as well as an analysis of these data in relation to the design and operation of the displays. Measurements of the luminance as a function of the screen current density and of the screen voltage of Zeus displays are reported. A white D65 luminance of 1000 Cd/m2 is obtained at a screen voltage of 4.5 kV and a screen current density of about 9 μA/cm2. The luminous efficacy of the phosphor screen in the panels is found to be 12 lm/W (in the absence of saturation) for white D65. The efficacy of a 17″ Zeus panel (including transport power dissipation, cathode heating power and addressing power) is about 4 lm/W. The factors determining the internal contrast and colour purity of Zeus panels are discussed. Experiments to determine the relevant contrast parameters are described as well as the results of direct measurements of the internal contrast, colour purity and colour selectivity. Internal contrast values of more than 1000 have been obtained, and a colour selectivity better than 700. The available colour gamut is close to that of CRTs. Preliminary measurements of the external contrast of 17″ panels with a black matrix and front glass with 50% optical transmission yield a contrast value of 60 at an ambient light level of 100 lux. The factors determining the picture uniformity in Zeus displays are discussed. Several panels with good uniformity have been realized. No artefacts associated with moving pictures occur, the only significant artefact is caused by charge transfer effects. The visibility of this effect can be sufficiently reduced by using suitable ‘flush’ pulses and by optimizing the geometry. The displays used for the performance measurements have a quincunx dot arrangement and dot pitches 0.5 × 0.6mm, giving PAL resolution on 28″ panels. Small experimental panels with pitches of 0.3 × 0.5 mm and 0.25 × 0.30 mm have been realized and operate satisfactorily. The viewing angle of Zeus displays is close to 180 degrees. Preliminary tests show that lifetimes well over 10,000 h are possible if the glass surfaces hit by electrons are covered with an MgO coating and if the blue phosphor is coated with a very thin calcium polyphosphate layer.
 
Article
A layered motion estimation algorithm is proposed that permits quasisimultaneous motion estimation/segmentation up to a fixed maximum number of layers. The estimation results in one motion parameter set per layer, and a segmentation map that assigns these sets to different parts of the image (motion layers). Motion in a layer is modelled with at maximum four parameters capable of describing pan, tilt and zoom. The concept shows some hierarchy, i.e. a ranking of the motion layers. In this way the motion parameter estimation concerning one layer excludes those parts of the image that have been described by a layer ranked higher in the hierarchy and are not polluted by parts of the image that are better described by layers ranked lower in the hierarchy. The concept results in a very low operations count. It has been shown to perform well even in critical scan rate conversion applications, particularly in picture rate up-conversion. A variant including three layers has been scheduled to run in real-time on a Philips TriMedia processor.
 
Article
An outlook is given on how the efficiency of future generation yoke-type magneto-resistive read heads may be improved through the use of oxidic layers. The effect of ferrite separation oxides, ferrite fluxguides and superconducting gap-oxides is discussed.
 
Article
The first thin film heads produced commercially by Philips were of the socalled sensor-first type, the sensor being processed on the substrate and the remaining parts of the head being processed on top of the sensor. This design has various drawbacks in comparison with a design where the sensor is processed at the end (sensor-last), such as a higher power consumption (low head efficiency) and limitations of use of high-temperature processes/materials. However, initially, topographic structures, step coverage and problems with wet chemical etching were obstacles in realizing the sensor-last design. The introduction of planarization in wafer processing technology opened the way to the sensor-last design. The design was introduced in heads for the DIGAMAXTM system and showed all the expected advantages in comparison with the sensor-first design. It also offers the possibility of applying new materials in the head, an option which is necessary for realizing new generations of recording systems.
 
Article
This paper reviews the research done on soft-magnetic fluxguide materials for use in sandwich heads and in thin-film recording heads for digital magnetic recording. After dealing with the basic principles of magnetic recording, the requirements on modern soft-magnetic materials are discussed. The roles of magnetic anistropy and magnetostriction in relation to permeability are discussed. Next, we review the recent advances in soft-magnetic materials processing, in particular for amorphous cobalt (CoNbZr) and nanocrystalline iron alloys, such as FeMX, with M being group IVa-Va metals such as Zr, Hf, Nb, Ta, etc., and X being N and O.
 
Article
The sensitivity of magnetoresistive read heads can be increased by using layered magnetic materials showing the giant magnetoresistance effect, instead of a single magnetic film showing the anisotropic magnetoresistance effect. For this purpose, exchange-biased spin-valve layered structures are very suitable. For well-chosen compositions and nanometer-scale layer thicknesses these materials combine a fair giant magnetoresistance effect with a very small field interval in which the resistance change takes place. In this paper we give an overview of aspects which determine the functioning of materials of this class in read heads, including their preparation, magnetotransport properties and the magnetic interactions which determine the magnetization reversal process.
 
Article
Metallization patterns are applied to the selection plates of the Zeus panel to be able to direct the electrons through the substructure to the proper colour pixel at the phosphor screen. The patterns, which also partially cover the insides of the holes in the selection plates, are applied using a subtractive process with either vacuum-deposited aluminium or wet-chemically applied silver. Different options for the lithographic resist are discussed, i.e. a cataphoretic negative resist and a sprayed positive resist. Satisfactory results have been obtained with both options. Adhesion of the metal to glass has been accomplished by application of a chromium adhesion layer in the case of the vacuum-deposited metal and by mechanical anchoring in the case of the wet-chemically applied metallization.
 
Article
In radiotherapy, portal images are used to ensure a correct patient position during every radiation session. A reliable on-line verification is of clinical interest to interrupt the radiation in time in case the patient is not at the right position. A great problem for successful image registration is the poor image quality of portal images. They are corrupted by noise and of very low contrast. A method directly based on the grey levels is not sufficient. Therefore a structure-based method was developed which is almost insensitive to distrubances (air bubbles, noise, slowly varying grey levels). In most cases the selection of a region of interest (ROI) can be omitted. Besides the automatical segmentation of the radiation field, only the structures relevant for matching the anatomy are enhanced by using a bandpass filter. It is possible to detect the maximum correlation between different image modalities reliably (simulator image, digitally reconstructed radiograph, portal image). By using Fast Fourier Transformation (FFT), the calculation time is smaller than five seconds, which enables a clinical on-line verification. We have matched 1139 pairs of images of different modalities and various regions of the body (pelvis, nasopharyngeal space, head, lung). The success rate is greater than 95%.
 
Article
Applications of the passive integration technology are described. A broad range of specific application examples are chosen with the aim of illustrating the possibilities for functional integration within this technology. The discussion is technical rather than commercial, to underline the advantages as well as the limitations of a passive integration approach. This paper is directly complementary to those on the technology of passive integration and on electromagnetic simulations of passive IC's in this edition.
 
Article
The characteristic features of direct bonding with respect to its many-sided aspects are briefly enumerated. Nowadays silicon-on-silicon and silicon-on-insulator are the trendsetters. The preparative conditions of direct bonding are compatible with silicon technologies. In addition, in the future, direct bonding may find dedicated applications in the field of hybrid material combinations, micromechanics for precision medical tools, sensors and actuators.
 
Article
Digital video transmission over satellite channels is described. Many systems have so far been proposed for satellite transmission, and exist in some form. Recently, the European Telecommunications Standard (ETS 300 421) has now been accepted by the Digital Audio-Video Interface Council (DAVIC) as the world standard. In the following, we describe the ETS 300 421 or the DVB-S (Digital Video Broadcasting-Satellite) standard. Specifically, the rationale for the selection of different parameters of the DVB-S standard is explained. Performance of the DVB-S system for a representative case is submitted. Finally, receiver performance issues are addressed.
 
Article
Developments in video compression and VLSI technologies are producing revolutionary changes in the television industry. Television signals worldwide are beginning to be compressed, encoded and transmitted using digital means. Using digital compression, encoding and transmission techniques has the advantage of better bandwidth utilization, flexibility and ease of integration with other digital data, and an overall higher quality of video at the receiver. The purpose of this paper is two-fold. Firstly, an introduction to video compression in the context of emerging digital television standards is provided. The important role played by International Standards, specifically MPEG, in the development of digital television systems is discussed. Secondly, current trends in the use of compression in the development of digital television for deployment in the United States and Europe, and the participation of Philips in these new applications, are discussed.
 
Article
In a Zeus display hopping electrons are transported through channels with extraction holes. If a sufficient transport field is applied, the electrons hop low and leakage through the holes is negligible. The electrons can be extracted from the channel by applying a positive voltage pulse to an extraction electrode. With sufficient pulse amplitude the extraction efficiency is 100 %, independent of small variations in material properties, which enables the creation of uniform images. Experiments on a model transport channel confirm the mechanisms behind transport and extraction.
 
Book
It is shown that theorem proving methods can lead to program synthesis and algorithm implementation by using pairs of logic laws: a deductive law for proving the theorem and a constructive law for synthesizing the program or algorithm. The construction of program schemata in an algorithmic programming environment and logic programming in a declarative programming environment appear as two particular and extreme cases of the model of pairs of laws acting on pairs of logic expressions. An examination of deductive laws and of constructive laws is presented. The set of all possible pairs of laws provides a tool for classifying the different approaches for materializing algorithms.
 
Article
The IEEE-1394 is a new standard for a digital high-speed serial interconnect bus. It allows real-time data to be mixed with other data transfers at transmission rates of 100, 200 and 400 Mbit/s. This makes it flexible enough for applications in multimedia environments where multiple video and audio streams have to be transported between several devices simultaneously. One of the most important applications in the consumer electronics world is MPEG-2 data transport between set-top box and digital video recorder. The extremely time-critical nature of MPEG-2 requires some additional processing before it can be sent on an IEEE-1394 bus. This has led to the standardization of the audio/video layer described in this article.
 
Article
One studies the possibility of evaluating the local values of a multivalued function by means of a specific type of algorithm called multivalued decision algorithm. The reason for this choice is its wide range of applications that encompasses both hardware and software problems. Possible applications of the multivalued decision algorithm are: combinatorial synthesis of discrete functions by means of multiplexers, sequential synthesis of discrete functions using multivalued ROM's and multiplexers, transformation and optimization of microprograms.
 
Article
The paper considers mode propagation in a straight optical fibre of arbitrary cross-section index profile, in the limit of small index contrast. A perturbation analysis is applied to the vector wave equation which governs the problem, with the zero-order limit corresponding to the generally assumed scalar approximation. Simple expressions are obtained for the first-order term in an asymptotic power series expansion of the mode propagation constants, in terms of the index contrast parameter. The effect is discussed of the various possible symmetries of the index profile.
 
Article
Although Magnetic Resonance Imaging (MRI) has faced a dramatic increase in real-time capabilities over the last year, acceptable image quality still limits the actually achievable acquisition speed. This paper presents a motion-compensated noise filter that, on the basis of hierarchical motion estimation and edge-preserving adaptive weighted averaging, has been integrated into a segmented radial MR acquisition scheme. In several studies of moving joints, the proposed approach led to significant reductions in the noise level without introducing motion blur. The improved image quality would, in principle, allow more than double the acquisition speed, retaining the original image quality.
 
Article
Electron transport over insulators sustained by secondary electron emission is studied using Monte Carlo calculations. With the aid of these Monte Carlo calculations, the steady-state potential distribution and the properties of the electron trajectories in various insulating structures are determined. Each of these structures represents a part of the Zeus display and together the results show how electrons, generated by the cathode, enter the transport channels and are transported through the Zeus display until they reach the phosphor screen. In the various cases, the results according to the Monte Carlo calculations agree well with the results of experiments.
 
Article
In spite of the present availability of advanced data transmission equipment based on the use of integrated digital processors for implementing various electronic functions, there is still a pronounced discrepancy between existing design possibilities for advanced LSI circuits and the actual practical applications. In the present paper, the reasons for the discrepancy between capability and application are discussed. A general survey of data modems is presented, and the possible role of digital signal processing in coping with the wide diversification of modems is examined.
 
Article
This paper describes recording experiments on magneto-optical media using nanosecond laser pulses for writing data. By reducing the length of the write pulses the effects of thermal diffusion are diminished. It is further shown that user bit lengths of 0.8 μm under pulse length modulation coding can be achieved without having to resort to a special write strategy. Some other beneficial effects of this method are pointed out for media as well as for laser requirements. Tests with commercially available laser diodes give insight into the possibilities of implementing short pulsed lasers in applications.
 
Article
Thin layers of MgO are applied in the Zeus panel to tower the field strength needed for electron transport. The layers can be applied by evaporation or spray pyrolysis. To achieve proper performance the layers should be smooth and at least 40 nm thick. MgO is easily degraded upon storage in air by the formation of a surface layer of magnesium carbonate and magnesium hydroxide. However, heating the contaminated layer briefly at a temperature of 450 °C in air is sufficient to regenerate the MgO surface.
 
Top-cited authors
Wolfgang Mecklenbräuker
Emile Aarts
  • Tilburg University
Peter van Laarhoven
Augustus Janssen
  • Eindhoven University of Technology
Robert Calderbank
  • Duke University