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Showing papers by "Philips published in 1994"


Journal ArticleDOI
TL;DR: Luminescent measurements show that the efficiency increases with decreasing size of the particles, as expected within the framework of an electron-hole localization theory, suggesting that doped nanocrystals are indeed a new class of materials heretofore unknown.
Abstract: We report for the first time that doped nanocrystals of semiconductor can yield both high luminescent efficiencies and lifetime shortening at the same time. Nanocrystals of Mn-doped ZnS with sizes varying from 3.5 to 7.5 nm were prepared by a room temperature chemical process. These nanosized particles have an external photoluminescent quantum efficiency as high as 18% at room temperature and a luminescent decay at least 5 orders of magnitude faster than the corresponding ${\mathrm{Mn}}^{2+}$ radiative transition in the bulk crystals. Luminescent measurements show that the efficiency increases with decreasing size of the particles, as expected within the framework of an electron-hole localization theory. These results suggest that doped nanocrystals are indeed a new class of materials heretofore unknown.

1,855 citations


Journal ArticleDOI
TL;DR: The problem of stochastic language modelling is studied from the viewpoint of introducing suitable structures into the conditional probability distributions, and nonlinear interpolation as an alternative to linear interpolation; equivalence classes for word histories and single words; cache memory and word associations are considered.

607 citations


Journal ArticleDOI
TL;DR: The major direct solutions to the three point perspective pose estimation problems are reviewed from a unified perspective beginning with the first solution published in 1841 by a German mathematician and continuing through the solutions published in the German and then American photogrammetry literature, and most recently in the current computer vision literature.
Abstract: In this paper, the major direct solutions to the three point perspective pose estimation problems are reviewed from a unified perspective beginning with the first solution which was published in 1841 by a German mathematician, continuing through the solutions published in the German and then American photogrammetry literature, and most recently in the current computer vision literature. The numerical stability of these three point perspective solutions are also discussed. We show that even in case where the solution is not near the geometric unstable region, considerable care must be exercised in the calculation. Depending on the order of the substitutions utilized, the relative error can change over a thousand to one. This difference is due entirely to the way the calculations are performed and not due to any geometric structural instability of any problem instance. We present an analysis method which produces a numerically stable calculation.

574 citations


Journal ArticleDOI
TL;DR: In this article, the authors focus on a CDMA design study for future third-generation mobile and personal communication systems such as FPLMTS and UMTS and adopt a rigorous top-down approach starting from the most essential objectives and requirements of universal 3G mobile systems.
Abstract: This paper focuses on a CDMA design study for future third-generation mobile and personal communication systems such as FPLMTS and UMTS. In the design study, a rigorous top down approach is adopted starting from the most essential objectives and requirements of universal third-generation mobile systems. Emphasis is laid on high flexibility with respect to the implementation of a wide range of services and service bit rates including variable rate and packet services. Flexibility in frequency and radio resource management, system and service deployment, and easy operation in mixed-cell and multioperator scenarios are further important design goals. The system concept under investigation is centered around an open and flexible radio interface architecture based on asynchronous direct-sequence CDMA with three different chip rates of approximately 1, 5, and 20 Mchip/s. The presented CDMA system concept forms the basis for an experimental test system (testbed) which is currently under development. This experimental system concept has been jointly established by the partners in the European RACE project R2020 (CODIT). The paper describes the radio transmission scheme and appropriate receiver principles and presents first performance results based on simulations. >

404 citations


Journal ArticleDOI
P. Löbl1, M. Huppertz1, D. Mergel1
TL;DR: In this article, the influence of the process parameters on the optical properties of TiO2 films, such as index of refraction, scattering of light, and absorption, is discussed.

388 citations


Journal ArticleDOI
TL;DR: In this article, an on/off ratio of about 2 orders of magnitude was obtained in a structure consisting of a 0.2 µm ferroelectric PbTi${\mathrm{O}}_{3}$ film, a Au Schottky contact, and a bottom electrode.
Abstract: A Schottky contact consisting of a semiconducting ferroelectric material and a high work function metal shows a bistable conduction characteristic. An on/off ratio of about 2 orders of magnitude was obtained in a structure consisting of a 0.2 \ensuremath{\mu}m ferroelectric PbTi${\mathrm{O}}_{3}$ film, a Au Schottky contact, and a ${\mathrm{La}}_{0.5}$${\mathrm{Sr}}_{0.5}$Co${\mathrm{O}}_{3}$ Ohmic bottom electrode. The observations are explained by a model in which the depletion width of the ferroelectric Schottky diode is determined by the polarization dependence of the internal electric field at the metal-ferroelectric interface.

381 citations


Patent
06 Jan 1994
TL;DR: In this paper, a broadband cholesteric polarizer is described, in which the pitch of the molecular helix in the layer is varied in such a manner that the difference between the maximum pitch and the minimum pitch is at least 100 nm.
Abstract: A broadband cholesteric polarizer is described, as well as a method of manufacturing such a polarizer. Said polarizer comprises an optically active layer of a polymer material having a cholesteric order, said material being oriented so that the axis of the molecular helix extends transversely to the layer. In accordance with the invention, the polarizer is characterized in that the pitch of the molecular helix in the layer is varied in such a manner that the difference between the maximum pitch and the minimum pitch is at least 100 nm. The optically active layers are preferably provided on substrates which bring about a conversion of circularly polarized light into linearly polarized light. Three different methods of manufacturing such broadband polarizers are described.

378 citations


01 Jan 1994
TL;DR: In this paper, a CDMA design study for future third-generation mobile and personal communication systems such as FPLMTS and UMTS is presented, focusing on high flexibility with respect to the implementation of a wide range of services and service bit rates including variable rate and packet services.
Abstract: This paper focuses on a CDMA design study for future third-generation mobile and personal communication systems such as FPLMTS and UMTS. In the design study, a rigorous top down approach is adopted starting from the most essential objectives and requirements of universal third-generation mobile systems. Emphasis is laid on high flexibility with respect to the implementation of a wide range of services and service bit rates including variable rate and packet services. Flexibility in frequency and radio resource management, system and service deployment, and easy operation in mixed-cell and multioperator scenarios are further important design goals. The system concept under investigation is centered around an open and flexible radio interface architecture based on asynchronous direct-sequence CDMA with three different chip rates of approximately 1,5, and 20 Mchip/s

336 citations


Journal ArticleDOI
TL;DR: In this article, the use of vectors containing the Tn903 kanr gene conferring G418-resistance was reported, which showed that copy number showed a tight correlation with drug resistance.
Abstract: Pichia pastoris is a methylotrophic yeast increasingly important in the production of therapeutic proteins. Expression vectors are based on the methanol-inducible AOX1 promoter and are integrated into the host chromosome. In most cases high copy number integration has been shown to be important for high-level expression. Since this occurs at low frequency during transformation, we previously used DNA dot blot screens to identify suitable clones. In this paper we report the use of vectors containing the Tn903 kanr gene conferring G418-resistance. Initial experiments demonstrated that copy number showed a tight correlation with drug-resistance. Using a G418 growth inhibition screen, we readily isolated a series of transformants, containing progressively increasing numbers (1 to 12) of a vector expressing HIV-1 ENV, which we used to examine the relationship between copy number and foreign mRNA levels. Northern blot analysis indicated that ENV mRNA levels from a single-copy clone were nearly as high as AOX1 mRNA, and increased progressively with increasing copy number so as to greatly exceed AOX1 mRNA. We have also developed protocols for the selection, using G418, of high copy number transformants following spheroplast transformation or electroporation. We anticipate that these protocols will simplify the use of Pichia as a biotechnological tool.

328 citations


Journal ArticleDOI
TL;DR: Chen et al. as discussed by the authors investigated the relation between the frame operator and the matrix of the matrix and showed that the matrix is bounded as a mapping of the identity operator into the matrix.
Abstract: Let $a>0, b>0, ab<1;$ and let $g\in L^2({\Bbb R}).$ In this paper we investigate the relation between the frame operator $S:f\in L^2({\Bbb R})\rightarrow \sum_{n,m}\,(f,g_{na,mb})\,g_{na,mb}$ and the matrix $H$ whose entries $H_{k,l\,;\,k',l'}$ are given by $(g_{k'/b,l'/a},g_{k/b,l/a})$ for $k,l,k',l'\in{\Bbb Z}.$ Here $f_{x,y}(t)={\rm exp}(2\pi iyt)\,f(t-x),$ $t\in{\Bbb R}$ , for any $f\in L^2({\Bbb R}).$ We show that $S$ is bounded as a mapping of $L^2({\Bbb R})$ into $L^2({\Bbb R})$ if and only if $H$ is bounded as a mapping of $l^2({\Bbb Z}^2)$ into $l^2({\Bbb Z}^2).$ Also we show that $AI\leq S\leq BI$ if and only if $AI\leq\frac{1}{ab}\,H\leq BI,$ where $I$ denotes the identity operator of $L^2({\Bbb R})$ and $l^2({\Bbb Z}^2),$ respectively, and $A\geq 0,$ $B<\infty.$ Next, when $g$ generates a frame, we have that $(g_{k/b,l/a})_{k,l}$ has an upper frame bound, and the minimal dual function $^{\circ}\gamma$ can be computed as $ab\,\sum_{k,l}\,(H^{-1})_{k,l\,;\,o,o}\,g_{k/b,l/a}.$ The results of this paper extend, generalize, and rigourize results of Wexler and Raz and of Qian, D. Chen, K. Chen, and Li on the computation of dual functions for finite, discrete-time Gabor expansions to the infinite, continuous-time case. Furthermore, we present a framework in which one can show that certain smoothness and decay properties of a $g$ generating a frame are inherited by $^{\circ}\gamma.$ In particular, we show that $^{\circ}\gamma\in{\cal S}$ when $g\in{\cal S}$ generates a frame $({\cal S}$ Schwartz space). The proofs of the main results of this paper rely heavily on a technique introduced by Tolimieri and Orr for relating frame bound questions on complementary lattices by means of the Poisson summation formula.

310 citations


Journal ArticleDOI
RM Jungblut1, R Reinder Coehoorn1, M.T. Johnson1, J. aan de Stegge1, A. Reinders1 
TL;DR: In this paper, a strong dependence of the exchange biasing field (Heb) and coercive field (Hc) on the growth orientation of Ni80Fe20 and Fe50Mn50 was observed in terms of the observed noncollinear spin structure of the antiferromagnet.
Abstract: The exchange biasing field (Heb) and coercive field (Hc) of molecular‐beam‐epitaxy‐grown Cu/Ni80Fe20/Fe50Mn50 samples in [111], [001], and [110] orientations have been investigated by longitudinal Kerr effect measurements. Ni80Fe20 and Fe50Mn50 were deposited as orthogonal wedge‐shaped layers on single‐crystal Cu substrates in a magnetic field, enabling the study of the thickness dependence of Heb and Hc on a single sample for each orientation. A strong dependence of Heb and Hc on the growth orientation is observed. The results are interpreted in terms of the observed noncollinear spin structure of the antiferromagnet and a comparison is given with the predictions from recent theoretical models.

Journal ArticleDOI
TL;DR: In this paper, a better modeling of the silicon bandgap at inversion conditions is presented, where E g QM = E g CONV + 13 9 Δ ϵ in which Δϵ is the position of the first energy level with respect to the bottom of the conduction band.
Abstract: The transistor parameters of state-of-the-art MOSFETs are affected by quantisation effects of the carrier motion in the inversion channel. To account for these effects in classical device stimulators, we show that a better modeling of the silicon bandgap at inversion conditions is ifE g QM = E g CONV + 13 9 Δϵ in which Δϵ is the position of the first energy level with respect to the bottom of the conduction band. The improved modeling of the bandgap leads to a new model for the intrinsic carrier concentration ni. The model for ni has been tested against measurements and against self-consistent QM calculations. Excellent agreement is obtained.

Book ChapterDOI
02 Jan 1994
TL;DR: In this paper an algorithm is described that finds collisions for the compression function of MD5 and results in an approximate relation between any four consecutive additive constants.
Abstract: At Crypto '91 Ronald L. Rivest introduced the MD5 Message Digest Algorithm as a strengthened version of MD4, differing from it on six points. Four changes are due to the two existing attacks on the two round versions of MD4. The other two changes should additionally strengthen MD5. However both these changes cannot be described as well-considered. One of them results in an approximate relation between any four consecutive additive constants. The other allows to create collisions for the compression function of MD5. In this paper an algorithm is described that finds such collisions.A C program implementing the algorithm establishes a work load of finding about 216 collisions for the first two rounds of the MD5 compression function to find a collision for the entire four round function. On a 33MHz 80386 based PC the mean run time of this program is about 4 minutes.

Journal ArticleDOI
TL;DR: The combination of supply scaling and self-timed circuitry which has some unique advantages, and the thorough analysis of the power savings that are possible using this technique are described.
Abstract: Recent research has demonstrated that for certain types of applications like sampled audio systems, self-timed circuits can achieve very low power consumption, because unused circuit parts automatically turn into a stand-by mode. Additional savings may be obtained by combining the self-timed circuits with a mechanism that adaptively adjusts the supply voltage to the smallest possible, while maintaining the performance requirements. This paper describes such a mechanism, analyzes the possible power savings, and presents a demonstrator chip that has been fabricated and tested. The idea of voltage scaling has been used previously in synchronous circuits, and the contributions of the present paper are: 1) the combination of supply scaling and self-timed circuitry which has some unique advantages, and 2) the thorough analysis of the power savings that are possible using this technique. >


Journal ArticleDOI
N. E. B. Cowern1, P. C. Zalm1, P. van der Sluis1, Dirk J. Gravesteijn1, W.B. de Boer1 
TL;DR: In this paper, the authors infer the mechanisms of Ge and B diffusion in strain-free and compressively strained Si(Ge) at T1030 \ifmmode^\circ\else\textdegree\fi{}C, and draw some general conclusions on strain modified diffusion in crystalline solids.
Abstract: Experiments on Si-rich SiGe layers show an exponential increase in Ge diffusion and an exponential decrease in B diffusion as a function of compressive strain, indicating a linear dependence of activation energy on strain. The effect arises from the structural relaxation of the lattice around the defect mediating diffusion (inward for a vacancy, outward for an interstitial). We infer the mechanisms of Ge and B diffusion in strain-free and compressively strained Si(Ge) at T1030 \ifmmode^\circ\else\textdegree\fi{}C, and draw some general conclusions on strain-modified diffusion in crystalline solids.

Patent
12 Aug 1994
TL;DR: In this paper, a data processing device consisting of a touch screen with a touch position sensor and a touch force sensor is presented, which is suitable for the combined processing of the position and force detected in response to touching.
Abstract: A data processing device comprises a touch screen with a touch position sensor. The position sensor is suitable to detect a touch position on the screen from a change in a current pattern in a conductive panel. The device also comprises a touch force sensor provided with a second conductive panel which extends substantially parallel to the touch screen. The screen is at least partly movable relative to the second panel in a direction transversely of the second panel. The force sensor is suitable to determine a force from a capacitance value between the touch screen and the second panel. The device is suitable for the combined processing of the position and force detected in response to touching.

Journal ArticleDOI
TL;DR: In this article, the luminescent properties of nanocrystals of Mn-doped ZnS with varying sizes from 30 to 70A˚prepared at room temperature were reported.

Journal ArticleDOI
TL;DR: The results demonstrate that the large signal changes, seen in previously reported gradient‐echo studies at 1.5–2.0 T, are dominated by direct inflow effects, in particular when using a large flip angle and a thin slice.
Abstract: Modified gradient-echo MR techniques were applied to study the effects of inflow on functional brain imaging studies using visual and motor cortex stimulation. The results demonstrate that the large signal changes, seen in previously reported gradient-echo studies at 1.5-2.0 T, are dominated by direct inflow effects, in particular when using a large flip angle and a thin slice. The findings suggest that inflow-based functional imaging, along with Blood Oxygenation Level Dependent (BOLD) functional MRI, may play an important role in future research towards the functional organization of the human brain.

Patent
21 Jul 1994
TL;DR: A microprocessor comprises a processor element, a memory interface element, an IO interface, a debug support element, and an internal bus interconnecting all above elements as mentioned in this paper for easy debugging, it also comprises attached to the internal bus a registered boundary scan standard (JTAG) interface that accesses one or more scan chains inside the microprocessor.
Abstract: A microprocessor comprises a processor element, a memory interface element, an IO interface element, a debug support element and an internal bus interconnecting all above elements For easy debugging, it also comprises attached to the internal bus a registered boundary scan standard (JTAG) interface that accesses one or more scan chains inside the microprocessor, and is arranged for controlling DMA-type exchanges via the internal bus with other elements connected to this bus

Patent
15 Mar 1994
TL;DR: In this article, a method and a device for providing (replicating) a patterned resyntetic resin relief (37) on the surface of a glass substrate was described.
Abstract: A description is given of a method and a device (1) for providing (replicating) a patterned resyntetic resin relief (37) on the surface (25) of a glass substrate (27). For this purpose, a UV-curable acrylate lacquer (33) is applied to the surface (25), after which a transparent mould (3) having a relief (13) is rolled-off over the surface (25). By means of a UV light source (17) and an elliptic mirror (21), the lacquer is cured at the location of the focal line (23), thereby forming said relief (37). The relief (13) of the mould (3) is replicated on the glass substrate (27). The method described enables a relief of small dimensions (10×10 μm) to be seamlessly provided on a large fiat surface (1×1 m), without being hindered by large release forces.

Patent
Yongping Xia1
06 May 1994
TL;DR: In this paper, a system for controlling the intensity of a lamp including a remote sensing device for detecting the presence of an occupant within an area was proposed, where a light controller responsive to the transmitted occupancy signal was used to reduce the level of illumination by the lamp.
Abstract: A system for controlling the intensity of a lamp including a remote sensing device for detecting the presence of an occupant within an area. The device also transmits a signal based on the currently sensed presence of the occupant. After each transmission of an occupancy signal, the device is inhibited from further transmission for a first predetermined period of time to limit power consumption requirements by the battery powered device. The system also includes a light controller responsive to the transmitted occupancy signal for controlling the level of illumination by the lamp. In the absence of a transmitted occupancy signal within a second predetermined period of time, the light controller will instruct the ballast to reduce the level of illumination by the lamp. In the absence of an occupancy signal being transmitted within a third predetermined time period, the light controller will instruct the ballast to turn off the lamp.

Patent
20 Dec 1994
TL;DR: In this article, a switching element is provided with two electrodes (1, 2) with a semiconducting dielectric (3) therebetween, one electrode (2) having a material which forms a Schottky contact with the semiconductor dielectrics (3), while a space charge region (3') of the Schottiness contact forms a tunnelling barrier for electrons during operation.
Abstract: A switching element is provided with two electrodes (1, 2) with a semiconducting dielectric (3) therebetween, one electrode (2) having a material which forms a Schottky contact with the semiconducting dielectric (3), while a space charge region (3') of the Schottky contact forms a tunnelling barrier for electrons during operation. It is desirable in many applications for the switching element to hold a certain switching state, such as open or closed, during a longer period. The switching element may then be used, for example, as a memory element. The dielectric (3) includes a ferroelectric material with a remanent polarization which influences a dimension of the tunnelling barrier. In this manner the switching element has various switching states depending on the remanent polarization of the dielectric (3). These switching states are held until the polarization of the dielectric (3) changes.

Journal ArticleDOI
TL;DR: In this paper, the progress in longwavelength compressively and tensile-strained InGaAs(P) quantum-well semiconductor lasers and amplifiers is reviewed.
Abstract: The progress in long-wavelength compressively and tensile-strained InGaAs(P) quantum-well semiconductor lasers and amplifiers is reviewed. By the application of grown-in strain, the device performance is considerably improved such that conventional bulk and unstrained quantum-well active-layer devices are outperformed, while a high reliability is maintained. >

Patent
15 Nov 1994
TL;DR: In this article, the average speeds for intervals of, for example, 15 seconds are stored, with the time and place of observation, and the data from all calibrant vehicles are then analyzed to determine patterns of mean speed and bandwidth.
Abstract: Monitoring of traffic on selected routes requires little communication time, through reporting only instances of abnormal speed. During a calibration phase calibrant vehicles are operated along the selected routes with sufficient frequency and for enough days to provide meaningful data. Each calibrant vehicle carries a differential GPS receiver for measuring location accurately. Average speeds for intervals of, for example, 15 seconds, are stored, with the time and place of observation. The data from all calibrant vehicles are then analyzed to determine patterns of mean speed and bandwidth. In the monitoring phase probe vehicles are deployed, each carrying similar GPS, a computer in which the patterns are stored, and a radio for automatically reporting speeds which are out of bandwidth for that time and place.

Patent
Americo Brajal1, Antoine Chouly1
21 Dec 1994
TL;DR: In this paper, a multicarrier frequency hopping spread spectrum communications system is proposed, where a transmitting station assigns encoded data symbols to particular ones of a predetermined series of fixed carrier frequencies, the frequency assignments being periodically mixed according to a frequency hopping code, and the encoded symbols are combined with their assigned carrier frequencies in accordance with an inverse Fourier transform so as to multiplex the encoded data symbol by orthogonal frequency division modulation.
Abstract: A multicarrier frequency hopping spread spectrum communications system wherein a transmitting station assigns encoded data symbols to particular ones of a predetermined series of fixed carrier frequencies, the frequency assignments being periodically mixed according to a frequency hopping code, and the encoded data symbols are combined with their assigned carrier frequencies in accordance with an inverse Fourier transform so as to multiplex the encoded data symbols by orthogonal frequency division modulation. A receiving station performs demultiplexing and de-mixing of such multiplexed signals in accordance with the inverse of the multiplexing and mixing performed at the transmitter. The system thereby provides frequency hopping operation without requiring a rapidly tunable and accurately phase controlled oscillator at each of the transmit/receive stations.

Patent
06 Jan 1994
TL;DR: In this paper, an illumination system consisting of a reflector, a cholesteric filter and a depolarizer was proposed to transmit radiation having a selected state of polarization in a selected wavelength range, while reflecting otherwise polarized radiation in that wavelength range.
Abstract: An illumination system comprising a reflector, a cholesteric filter and a depolarizer. The cholesteric filter is arranged between a radiation source and, in a display device, a display panel, and is selected to transmit radiation having a selected state of polarization in a selected wavelength range, while reflecting otherwise polarized radiation in that wavelength range. The depolarizer is disposed between the reflector and the cholesteric filter. Radiation reflected by the cholesteric filter is re-reflected to the filter by the reflector and, having been depolarized in the depolarizer, is transmitted to the extent it has the selected state of polarization in the selected wavelength.

Journal ArticleDOI
Dago M. de Leeuw1, P.A. Kraakman1, P.F.G. Bongaerts1, C.M.J. Mutsaers1, D.B.M. Klaassen1 
TL;DR: In this article, N -(3-Trimethoxysilyl-propyl)pyrrole was applied as a primer to adhere poly(3,4-ethylenedioxythiophene) (PEDOT) to the substrate.

Patent
14 Oct 1994
TL;DR: In this article, the nanoparticles are precipitated and coated with a surfactant by precipitation in an organometallic reaction and the luminescence of the particles may be increased by a further UV curing step.
Abstract: Doped encapsulated semiconductor nanoparticles of a size (<100 Å) which exhibit quantum effects. The nanoparticles are precipitated and coated with a surfactant by precipitation in an organometallic reaction. The luminescence of the particles may be increased by a further UV curing step.

Journal ArticleDOI
TL;DR: Near-edge x-ray-absorption fine structures indicate that the effective valency of Mn ions in the nanocrystals is close to +2 with a weak size dependence, which is believed to be closely related to the novel optical properties observed in this new class of semiconductors.
Abstract: X-ray-absorption fine-structure measurements were carried out to probe the local environment surrounding Mn ions in Mn-doped nanocrystals of ZnS with different size distributions ranging from 30--35 \AA{} to 50--55 \AA{}. The interatomic distances between Mn and neighboring atoms, the coordination number, local disorder, and effective valency determined for the nanocrystals are compared with those in bulk Mn-doped ZnS. The Mn ions are found to substitute for the Zn sites in the host ZnS but with significant size-dependent local structural changes. The questions of Mn-cluster formation and the presence of Mn impurities on the surface of the nanocrystals are addressed. Near-edge x-ray-absorption fine structures indicate that the effective valency of Mn ions in the nanocrystals is close to +2 with a weak size dependence. These local structures are believed to be closely related to the novel optical properties observed in this new class of semiconductors.