| 1. |
- Danielsson, Per-Erik
(författare)
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Implementations of the Convolution Operation
- 1982
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The first part of this article surveys a large number of implementations of the convolution operation (which is also known as the sum-of-products, the inner product) based on a systematic exploration of index permutations. First we assume a limited amount of parallelism in the form of an adder. Next, multipliers and RAM:s are utilized. The so called distributed arithmetic follows naturally from this approach.The second part brings in the concept of pipelining on the bitlevel to obtain high throughput convolvers adapted for VLSI-design (systolic arrays). The serial/parallel multiplier is analyzed in a way that unravels a vast amount new variations. Even more interesting, all these new variations can be carried over to serial/parallel convolvers. These novel devices can be implemented as linear structures of identical cells where the multipliers are embedded at equidistant intervals.
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| 2. |
- Eriksson, T., et al.
(författare)
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Successive Encoding of Correlated Sources
- 1982
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The encoding of a discrete memoryless multiple source for reconstruction of a sequence with is considered. We require that the encoding should be such that is encoded first without any consideration of , while in a seeond part of the encoding this latter sequence is encoded based on knowledge of the outcome of the first encoding. The resulting scheme is called successive encoding. We find general outer and inner bounds for the corresponding set of achievable rates along with a complete single letter characterization for the special case . Comparisons with the Slepian-Wolf problem [3] and the Ahlswede-Körner-Wyner side information problem [2 ], [9) are carried out.
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| 3. |
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| 4. |
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| 5. |
- Wernersson, Åke, et al.
(författare)
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Vehicle navigation using image information on association errors
- 1989
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Ingår i: Intelligent autonomous systems. - Amsterdam : Stichting International Congress of Intelligent Autonomous Systems. - 9080041033 ; , s. 814-822
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Konferensbidrag (refereegranskat)abstract
- Describes how image-like measurements can be used for accurate navigation of a vehicle. The `camera' is a rotating laser scanner and the `landmarks' are stripes of identical retroreflecting tape. This arrangement can be seen as a linear circular 360 degree camera with a rotating scanning at a rate of 1 scan/second. The most likely objects the `camera' will see are these identical pieces of tape. Tests were carried out using an AGV (Autonomous Guided Vehicle) running on a floor. At a speed of 0.3 m/s the trajectory fluctuates less than ±2 mm. For this special case it is possible to give a fairly complete and rigorous mathematical model. The model includes the motion, the sensor, missing and erroneous measurements etc
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| 6. |
- Wiklund, Urban, et al.
(författare)
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AGV navigation by angle measurements
- 1988
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Ingår i: Automated guided vehicle systems. - Kempston, Bedford : IFS. - 1854230247 ; , s. 199-212
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Konferensbidrag (refereegranskat)abstract
- Describes an optical navigation system for the navigation and control of an autonomous guided vehicle (AGV). The navigation system consists of a low-power laser, a rotating mirror and the necessary optics. It is used to measure the angles to several identical reflective beacons. The position and heading of the AGV is recursively updated each time a valid angle is measured. It is easy to define and change the drive path which is a list of coordinates. The AGV follows straight lines between these coordinates. The system has been tested on an AGV prototype
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| 7. |
- Boström, Anders E, 1951, et al.
(författare)
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Transmission and reflection of electromagnetic waves by an obstacle inside a waveguide
- 1981
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 52, s. 1187-1196
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Tidskriftsartikel (refereegranskat)abstract
- We consider the transmission and reflection of electromagnetic waves by an obstacle inside a waveguide. The method employed is an adaptation of the null‐field approach (T‐matrix method). The geometry is more or less arbitrary, but only for a waveguide with constant cross section can we obtain the scattered field in a not too formal way. For a circular cross section we derive comparatively explicit expressions for the transmission and reflection coefficients of the obstacle, and we give numerical results for spherical and spheroidal obstacles in rotationally symmetric geometries. As an important part of the theory, we have derived some apparently new transformations between the cylindrical and spherical vector waves and also expansions of the free‐space Green’s dyadic in cylindrical vector waves.
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| 8. |
- Karlsson, Anders, et al.
(författare)
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Constitutive relations, dissipation and reciprocity for the Maxwell equations in the time domain
- 1989
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The main goal of this paper is to establish general constitutive relations for the electromagnetic fields E,D,B and H in a time domain setting. The four basic assumptions of the medium are linearity, invariance to time translations, causality and continuity. These four assumptions imply that the constitutive relations are convolutions of Riemann-Stieltjes type. A review of the classifi- cation of media in bianisotropic, biisotropic, anisotropic and isotropic media, respectively, is made. Dissipation and reciprocity are defined and the constraints these concepts make on the constitutive relations are analyzed in detail. Furthermore, an appropriate form of time reversal and functions of positive type are introduced and some consequences of these concepts are showed.
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| 9. |
- Karlsson, Anders, et al.
(författare)
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Wave splitting in the time domain for a radially symmetric geometry
- 1989
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- A decomposition of the field of the wave equation in three dimensions is suggested. This wave splitting decomposes the field into two components such that in free space simple propagation properties are obtained. The inhomogeneous region is assumed to have a phase velocity variation that varies only in the radial coordinate r from the origin. The suggested wave splitting is a generalization of the wave splitting concept in one spatial dimension. Specifically, the propagation properties in free space in the three-dimensional wave splitting are very analogous to the corresponding propagation properties in free space in one dimension. The three-dimensional decomposition is illustrated in an example of scattering by a sound-soft sphere of radius a.
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| 10. |
- Lundin, Richard
(författare)
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A general power-series expansion method for scalar analysis of the guided modes in an optical fiber
- 1987
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- A power-series expansion method for approximate analysis of the guided modes in a cylindrical, radially inhomogeneous dielectric waveguide is presented. The method is developed for a piece-wise polynominal permittivity profile. The solution of the scalar wave equation is constructed by a sequence of power-series expantions. Convergence is ensured and accuracy maintained by regulating the distance (= the steplength ) between successive expansion points. It is demonstrated, by analytical reasoning and numerical examples, that a short steplength is insufficient. The characteristic equation and the cutoff condition are expressed in a unified manner. The method presented is competetive in terms of accuracy achieved and computing time required.
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