Showing papers by "Philips published in 1997"

Electric-field and temperature dependence of the hole mobility in poly(p-phenylene vinylene)

Abstract: The current-voltage characteristics of poly(dialkoxy p-phenylene vinylene)-based hole-only devices are measured as a function of temperature. The hole current is space-charge limited, which provides a direct measurement of the hole mobility ${\mathrm{\ensuremath{\mu}}}_{\mathrm{p}}$ as a function of electric field E and temperature. The hole mobility exhibits a field dependence ln ${\mathrm{\ensuremath{\mu}}}_{\mathrm{p}}$\ensuremath{\propto}$\sqrt{E}$ as has also been observed from time-of-flight experiments in many molecularly doped polymers and amorphous glasses. For the zero-field hole mobility an activation energy of 0.48 eV is obtained. The combination of a field-dependent mobility and space-charge effects provides a consistent description of the hole conduction in conjugated polymer films as a function of voltage, temperature, and layer thickness.

A paraperspective factorization method for shape and motion recovery

Abstract: The factorization method, first developed by Tomasi and Kanade (1992), recovers both the shape of an object and its motion from a sequence of images, using many images and tracking many feature points to obtain highly redundant feature position information. The method robustly processes the feature trajectory information using singular value decomposition (SVD), taking advantage of the linear algebraic properties of orthographic projection. However, an orthographic formulation limits the range of motions the method can accommodate. Paraperspective projection, first introduced by Ohta et al. (1981), is a projection model that closely approximates perspective projection by modeling several effects not modeled under orthographic projection, while retaining linear algebraic properties. Our paraperspective factorization method can be applied to a much wider range of motion scenarios, including image sequences containing motion toward the camera and aerial image sequences of terrain taken from a low-altitude airplane.

Roadmapping Integrates Business and Technology

Abstract: OVERVIEW:The product–technology roadmap process developed at Philips Electronics aims at better integration of business and technology strategy and improvement of the front end of the product creation process (the concept and idea phase). The outcomes are roadmaps that present products and technologies required to realize these products, as well as their mutual relationship over a five-year period. Teamwork, integral involvement by the organization and good communication are essential characteristics of the process. Benefits include a shared product–technology strategy and a cross-functional approach to product and technology planning and vision building. The roadmap drafting process can be supported by such tools as maturity grid, Quality Function Deployment and the Innovation Matrix.

Absolute light output of scintillators

Abstract: The absolute light outputs of BGO, CsI(Tl) and some new Ce-doped crystals have been measured to an accuracy of about /spl plusmn/5% using calibrated XP2020Q photomultipliers and standard S3590.03 and S2740.03 photodiodes. The use of small crystals, 9 mm in diameter and 1 mm thick, reduces the corrections for imperfections in the light collection process and in the photoelectron collection by the photomultipliers. The measured light-output of 8500/spl plusmn/350 ph/MeV (photons/MeV) for the BGO crystals agree well with the earlier measurement done by Holl et al. (1988). The carried out study highlighted the importances of the spread in the published emission spectra of the crystals which seems to limit measurement accuracy. Finally, a simple comparative method of measuring light output to an accuracy of /spl plusmn/10%, is proposed using an uncalibrated XP2020 photomultiplier and a 1 mm thick BGO crystal as a standard.

Multi-scale line segmentation with automatic estimation of width, contrast and tangential direction in 2D and 3D medical images

Abstract: A new multi-scale segmentation technique for line-like structures in 2D and 3D medical images is presented. It is based on normalized first and second derivatives and on the eigenvector analysis of the hessian matrix. Application areas are the segmentation and tracking of bloodvessels, electrodes, catheters and other line-like objects. It allows for the estimation of the local diameter, the longitudinal direction and the contrast of the vessel and for the distinction between edge-like and line-like structures. The method is applicable as automatic 2D and 3D line-filter, as well as for interactive algorithms that are based on local direction estimation. A 3D line-tracker has been constructed that uses the estimated longitudinal direction as step-direction. After extraction of the centerline, the hull of the structure is determined by a 2D active-contour algorithm, applied in planes, orthogonal to the longitudinal line-direction. The procedure results in a stack of contours allowing quantitative crosssection area determination and visualization by means of a triangulation based rendering.

Differential interferometer system and lithographic step-and-scan apparatus provided with such a system

Abstract: A differential interferometer system for measuring the mutual positions and movements of a first object (WH) and a second object (MH) is described, which system comprises a first interferometer unit (1, 2, 3, 4) with a first measuring reflector (RW) and a second interferometer unit (5, 6, 7, 8) with a second measuring reflector (RM). Since a measuring beam (bm) passes through both the first and the second interferometer unit and is reflected by both the first and the second measuring reflector, and since the measuring beam and the reference beam (br) traverse the same path at least between the two interferometer units, accurate measurements can be performed very rapidly. The interferometer system may be used to great advantage in a step-and-scan lithographic projection apparatus.

Video retrieval of MPEG compressed sequences using DC and motion signatures

Abstract: Signatures from MPEG or Motion JPEG encoded video clips are extracted based on the luminance, chrominance, and motion vector values. The signatures are stored in a database, along with corresponding location, size, and time length information. The signature of a query video clip, also encoded in the MPEG or Motion JPEG format, is extracted. The signature of the query video clip is comparred with the signatures stored in the meta database, with video clips having signatures similar to the signature of the query video clip identified. The video clips are then retrieved and displayed by selection of a user.

An approach for quantitative analysis of application-specific dataflow architectures

Abstract: In this paper we present an approach for quantitative analysis of application-specific dataflow architectures. The approach allows the designer to rate design alternatives in a quantitative way and therefore supports him in the design process to find better performing architectures. The context of our work is video signal processing algorithms which are mapped onto weakly-programmable, coarse-grain dataflow architectures. The algorithms are represented as Kahn graphs with the functionality of the nodes being coarse-grain functions. We have implemented an architecture simulation environment that permits the definition of dataflow architectures as a composition of architecture elements, such as functional units, buffer elements and communication structures. The abstract, clock-cycle accurate simulator has been built using a multi-threading package and employs object oriented principles. This results in a configurable and efficient simulator. Algorithms can subsequently be executed on the architecture model producing quantitative information for selected performance metrics. Results are presented for the simulation of a realistic application on several dataflow architecture alternatives, showing that many different architectures can be simulated in modest time on a modern workstation.

Perpendicular giant magnetoresistance of magnetic multilayers

Abstract: The theoretical and experimental studies of the giant magnetoresistance effect in metallic magnetic multilayers with measuring current perpendicular to the interface planes are reviewed. Theoretical formalisms of electronic transport in the inhomogeneous electron gas are critically compared with emphasis on the perpendicular magnetoresistance in multilayers. The effects of interface roughness, potential steps at the interfaces, and realistic band structures are addressed. The experimental determination of the perpendicular resistance of metallic multilayers requires either low-resistance measurement techniques or microfabricated samples with enhanced resistances. The experimental methods known at present are discussed and, where possible, compared with each other.

Linear motor motion control using a learning feedforward controller

Abstract: The design and realization of an online learning motion controller for a linear motor is presented, and its usefulness is evaluated. The controller consists of two components: (1) a model-based feedback component, and (2) a learning feedforward component. The feedback component is designed on the basis of a simple second-order linear model, which is known to have structural errors. In the design, an emphasis is placed on robustness. The learning feedforward component is a neural-network-based controller, comprised of a one-hidden-layer structure with second-order B-spline basis functions. Simulations and experimental evaluations show that, with little effort, a high-performance motion system can be obtained with this approach.

Detecting a watermark embedded in an information signal

Abstract: A watermark embedded in an information signal is detected by correlating said information signal with a plurality of watermarks Wj(n) The respective amounts of correlation C(i,j) are then evaluated to determine the watermark embedded in the signal xi(n) The invention provides a significant improvement of the detection by predictive filtering (25) the information signal and/or predictive filtering (26) the applied watermark prior to the process of correlating the signals

Analog-to-digital conversion via duty-cycle modulation

Abstract: An exchange of the amplitude axis for the time axis offers a possibility of overcoming resolution problems in analog-to-digital conversion in low-voltage CMOS circuits and/or of circumventing special resistor options in silicided processes. This exchange can be effected via some form of duty-cycle modulation. For its implementation a circuit configuration is described, consisting of an asynchronous sigma-delta modulator, followed by a phase-synchronized tapped ring oscillator which produces a poly-phase signal for sampling the asynchronous signal at a relatively low frequency. A detailed analysis is presented which accurately predicts the properties of the conversion scheme with respect to aliasing, quantization noise and nonlinear distortion. The results are illustrated with simulations of a design example.

Solution of the time-dependent Boltzmann equation

Abstract: The time-dependent Boltzmann equation, which describes the propagation of radiation from a point source in a random medium, is solved exactly in Fourier space. An explicit expression in real space is given in two and four dimensions. In three dimensions an accurate interpolation formula is found. The average intensity at a large distance $r$ from the source has two peaks, a ballistic peak at time $t=r/c$ and a diffusion peak at $t\ensuremath{\simeq}{r}^{2}/D$ (with $c$ the velocity and $D$ the diffusion coefficient). We find that forward scattering adds a tail to the ballistic peak in two and three dimensions, $\ensuremath{\propto}(ct\ensuremath{-}{r)}^{\ensuremath{-}1/2}$ and $\ensuremath{\propto}\ensuremath{-}\mathrm{ln}(ct\ensuremath{-}r)$, respectively. Expressions in the literature do not contain this tail.

Quantum melting of magnetic order due to orbital fluctuations

Abstract: We have studied the phase diagram and excitations of the spin-orbital model derived for a three-dimensional perovskite lattice, as in ${\mathrm{KCuF}}_{3}$. The results demonstrate that the orbital degeneracy drastically increases quantum fluctuations and suppresses the classical long-range order near the multicritical point in the mean-field phase diagram. This indicates the presence of a quantum liquid state, and we present explicit evidence for valence bond type correlations in three dimensions.

Battery management system and battery simulator

Abstract: A battery management system (100) comprises input means (102) for receiving input signals, such as current or voltage, which represent a physical quantity of a battery. In operation, processing means (105) of the battery management system (100) calculate a physical quantity of the battery, such as the State of Charge, based on the input signals by using an electrochemical/physical model of the battery. The model includes a representation of a main electrochemical storage reaction, whose behaviour is calculated in dependence on a battery temperature. The processing means (105) calculates the battery temperature based on a temperature model of a temperature development in the battery. The battery management system (100) comprises output means (104) for outputting an output signal which is derived from a state of the electrochemical storage reaction. The battery management system (100) is, advantageously, used in a smart battery (10) or a battery charger/discharger (200). The model is, advantageously, also used in a battery simulator.

Medium access control (mac) protocol for wireless atm

Abstract: A protocol, method, and apparatus for managing network communications are disclosed which are particularly well suited for ATM communications across a wireless medium. Contiguous time slots within a frame are allocated to each node having traffic to send. Each node is assured a nominal bandwidth, and excess bandwidth is distributed by demand. The allocation of excess bandwidth can be dependent upon the size of the buffer at each node, as well as the time-criticality of each message. Nodes communicate their requests for allocation by appending such control information to the first of their transmitted packets. The allocation, of each node's transmit and receive time slots, is transmitted to all the nodes at the beginning of each frame. Thereafter, each node need not participate on the network until their allocated time periods, thereby allowing portable devices to enter inactive states to conserve power. The network is operated in a connection mode; connections are established in a relatively non-interfering manner by the use of periodically occuring beacons. Inactive, unconnected, nodes need only monitor the network during these beacon periods, further allowing for power conservation.

Tomographic image reconstruction from optical projections in light-diffusing media.

Abstract: The recent developments in light generation and detection techniques have opened new possibilities for optical medical imaging, tomography, and diagnosis at tissue penetration depths of ∼10 cm. However, because light scattering and diffusion in biological tissue are rather strong, the reconstruction of object images from optical projections needs special attention. We describe a simple reconstruction method for diffuse optical imaging, based on a modified backprojection approach for medical tomography. Specifically, we have modified the standard backprojection method commonly used in x-ray tomographic imaging to include the effects of both the diffusion and the scattering of light and the associated nonlinearities in projection image formation. These modifications are based primarily on the deconvolution of the broadened image by a spatially variant point-spread function that is dependent on the scattering of light in tissue. The spatial dependence of the deconvolution and nonlinearity corrections for the curved propagating ray paths in heterogeneous tissue are handled semiempirically by coordinate transformations. We have applied this method to both theoretical and experimental projections taken by parallel- and fan-beam tomography geometries. The experimental objects were biomedical phantoms with multiple objects, including in vitro animal tissue. The overall results presented demonstrate that image-resolution improvements by nearly an order of magnitude can be obtained. We believe that the tomographic method presented here can provide a basis for rapid, real-time medical monitoring by the use of optical projections. It is expected that such optical tomography techniques can be combined with the optical tissue diagnosis methods based on spectroscopic molecular signatures to result in a versatile optical diagnosis and imaging technology.

UV/blue LED-phosphor device with short wave pass, long wave pass band pass and peroit filters

Abstract: A visible light emitting device for use in lighting and/or display applications includes a UV LED, a phosphor layer on the upper, main light emitting surface of the LED, and a short wave pass (SWP) filter between the LED and the phosphor layer to transmit UV light from the LED to the phosphor layer, as well as to reflect visible light from the phosphor layer in a forward direction, thus enhancing the efficiency of the device. Additional optical filters located on the top of the phosphor layer further enhance efficiency and/or spectral characteristics of the emitted light.

Payment scheme for a mobile communication service

Abstract: In a mobile communication system, communication credits are stored in a secure module (30) of a mobile communication appliance (10). Credits are reloaded over-the-air (OTA) from a reload server (20). For requesting a reload, the secure module (30) generates an authenticated reload request message (50), which is transmitted to the reload server (20). In response to receiving the reload request message (50), the reload server (20) informs the secure module (30) of how many credits have been granted in the form of an authenticated reload grant message (60). Successive messages are made to differ by using different transaction numbers. A received authenticated message is only accepted if a transaction number in the message matches a local transaction number.

Propionate oxidation in Escherichia coli: evidence for operation of a methylcitrate cycle in bacteria

Abstract: Escherichia coli grew in a minimal medium on propionate as the sole carbon and energy source. Initially a lag phase of 4–7 days was observed. Cells adapted to propionate still required 1–2 days before growth commenced. Incorporation of (2-13C), (3-13C) or (2H3)propionate into alanine revealed by NMR that propionate was oxidized to pyruvate without randomisation of the carbon skeleton and excluded pathways in which the methyl group was transiently converted to a methylene group. Extracts of propionate-grown cells contained a specific enzyme that catalyses the condensation of propionyl-CoA with oxaloacetate, most probably to methylcitrate. The enzyme was purified and identified as the already-known citrate synthase II. By 2-D gel electrophoresis, the formation of a second propionate-specific enzyme with sequence similarities to isocitrate lyases was detected. The genes of both enzymes were located in a putative operon with high identities (at least 76% on the protein level) with the very recently discovered prp operon from Salmonella typhimurium. The results indicate that E. coli oxidises propionate to pyruvate via the methylcitrate cycle known from yeast. The 13C patterns of aspartate and glutamate are consistent with the further oxidation of pyruvate to acetyl-CoA. Oxaloacetate is predominantly generated via the glyoxylate cycle rather than by carboxylation of phosphoenolpyruvate.

Voxel-based 2-D/3-D registration of fluoroscopy images and CT scans for image-guided surgery

Abstract: Registration of intraoperative fluoroscopy images with preoperative 3D CT images can he used for several purposes in image-guided surgery. On the one hand, it can be used to display the position of surgical instruments, which are being tracked by a localizer, in the preoperative CT scan. On the other hand, the registration result can be used to project preoperative planning information or important anatomical structures visible in the CT image on to the fluoroscopy image. For this registration task, a novel voxel-based method in combination with a new similarity measure (pattern intensity) has been developed. The basic concept of the method is explained at the example of 2D/3D registration of a vertebra in an X-ray fluoroscopy image with a 3D CT image. The registration method is described, and the results for a spine phantom are presented and discussed. Registration has been carried out repeatedly with different starting estimates to study the capture range. Information about registration accuracy has been obtained by comparing the registration results with a highly accurate "ground-truth" registration, which has been derived from fiducial markers attached to the phantom prior to imaging. In addition, registration results for different vertebrae have been compared. The results show that the rotation parameters and the shifts parallel to the projection plane can accurately be determined from a single projection. Because of the projection geometry, the accuracy of the height above the projection plane is significantly lower.

Novel fingerprint scanning arrays using polysilicon TFT's on glass and polymer substrates

Abstract: Novel fingerprint scanning arrays based upon capacitance sensing have been made Each sensor element consists of a capacitor electrode and two poly-Si thin film transistors for addressing and read out The devices were fabricated on glass, polyimide and polyethersulphone substrates using a low temperature (<250/spl deg/C) process