1.
Danielsson, Per-Erik
(author)
Implementations of the Convolution Operation
1982
Reports (other academic/artistic) 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.
2.
3.
4.
Wernersson, Åke, et al.
(author)
Vehicle navigation using image information on association errors
1989
In: Intelligent autonomous systems. - Amsterdam : Stichting International Congress of Intelligent Autonomous Systems. - 9080041033 ; , s. 814-822
Conference paper (peer-reviewed) 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
5.
Wiklund, Urban, et al.
(author)
AGV navigation by angle measurements
1988
In: Automated guided vehicle systems. - Kempston, Bedford : IFS. - 1854230247 ; , s. 199-212
Conference paper (peer-reviewed) 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
6.
Rehnberg, Ove, et al.
(author)
Controlling diesel emissions underground
1982
In: World Mining. - 0043-8707. ; 35:6, s. 48-52
Journal article (peer-reviewed) abstract
An enquiry to the Swedish mining industry included questions concerning planned mine production, mining methods, number and types of diesel-powered equipment, diesel engines, and transmission types of working cycles. The result representing the situation in 1977 in 37 mines are shown. LHD's are the main fuel consumers (50 percent) and the main contaminators of the air. Subsequent work was concentrated on a duty cycle for this type of equipment.
7.
Schmidtbauer, Bengt, et al.
(author)
Reproduction of transient load cycles of diesel powered mining vehicles by computer control for exhaust emission testing
1981
In: ISATA 81. - Croydon : Automotive automation.
Conference paper (peer-reviewed) abstract
A large set of actual load cycles for LHD-machines in hard rock mining was obtained through in field test measurements using automatic monitoring equipment. Based on a statistical analysis of this measurement set, a few representative time records of engine speed and load variations were chosen for emission testing. A dynamic measurement of exhaust emissions during the representative load cycles showed to be in good agreement with corresponding static exhaust emission characteristics. Based on the results of this work, a reference cycle for underground LHD diesel operation has been suggested
8.
Boström, Anders E, 1951, et al.
(author)
Transmission and reflection of electromagnetic waves by an obstacle inside a waveguide
1981
In: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 52, s. 1187-1196
Journal article (peer-reviewed) 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.
9.
Karlsson, Anders, et al.
(author)
Constitutive relations, dissipation and reciprocity for the Maxwell equations in the time domain
1989
Reports (other academic/artistic) 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.
10.
Karlsson, Anders, et al.
(author)
Wave splitting in the time domain for a radially symmetric geometry
1989
Reports (other academic/artistic) 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.
11.
Lundin, Richard
(author)
A general power-series expansion method for scalar analysis of the guided modes in an optical fiber
1987
Reports (other academic/artistic) 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.
12.
Lundin, Richard
(author)
A handbook formula for the inductance of a single-layer circular coil
1985
In: Proceedings of the IEEE. - 0018-9219. ; 73:9, s. 9-1428
Journal article (peer-reviewed) abstract
A compact six-figure approximation formula for the inductance of a cylindrical current sheet is presented. The formula displays the correct asymptotic behavior in the respective cases of very long and very short coils. The efficiency of the approximation formula is due to a thorough analysis of the exact formula.
13.
Lundin, Richard
(author)
Efficient approximation of the inductance of a cylindrical current sheet
1984
Reports (other academic/artistic) abstract
This report comprises the article "Efficient approximation of the inductance of a cylindrical current sheet" and two supplementary sections. The first section treats the question of how to calculate the inductance of a coil. The second section is aimed at providing a theoretical background to the computed approximations of the article. The second section is also intended to demonstrate that the efficiency of the approximated computations is the result of a systematic approach.
14.
15.
16.
17.
Davis, J.L, et al.
(author)
Geodesy by radio interferometry: Effects of atmospheric modeling errors on estimates of baseline length
1985
In: Radio Science. - 0048-6604 .- 1944-799X. ; 20:6, s. 1593-1607
Journal article (peer-reviewed) abstract
Analysis of very long baseline interferometry data indicates that systematic errors in prior estimatesof baseline length, of order 5 cm for ~8000-km baselines, were due primarily to mismodeling of theelectrical path length of the troposphere and mesosphere ("atmospheric delay"). Here we discussobservational evidence for the existence of such errors in the previously used models for the atmosphericdelay and develop a new "mapping" function for the elevation angle dependence of this delay. Thedelay predicted by this new mapping function differs from ray trace results by less than ~5 mm, at allelevations down to 5° elevation, and introduces errors into the estimates of baseline length of •
18.
Brännlund, Håkan
(author)
Network Programming Applied too Operation Planning of Hydrothermal Power Systems
1986
Doctoral thesis (other academic/artistic) abstract
The objective of the project was to develop models and methods suitable for computer implementation. In particular, this work has been devoted to generation scheduling of a power system with a sizeable amount. of hydro energy. Optimal operation planning of hydrothermal power systems aims at minimizing incurred production costs while supplying customer demand. The planning horizon may vary from one day to several years and the associated planning problems are categorized as short term, seasonal and long term operation planning. The topic of this thesis is short term operation planning.In this planning, it is necessary to use detailed models of the different parts of the power system. These include models of cascaded reservoirs in a multi-river system as we11 as a representation of the nonlinear generating characteristics of the hydro plants.he thermal generating units are modelled using linear production cost curves and by recognizing various technical constraints associated with the operation of these plants.Effects on the optimal operating strategy caused by interregional transmission capacity limitations are also accounted for by the model. These constraints are modelled to main1y affect the hydro plant operation.
19.
20.
21.
Bengtsson, Stefan, 1961, et al.
(author)
IC process compatible preparation of silicon interfaces using the silicon-to-silicon direct bonding method
1989
In: ESSDERC '89. 19th European Solid State Devices Research Conference. ; , s. 353-
Conference paper (peer-reviewed) abstract
Silicon/silicon interfaces were prepared by wafer bonding using the silicon-to-silicon direct bonding method. Silicon/silicon interfaces (n/n-type) with excellent electric properties were prepared, by using hydrophobic wafer surfaces, at temperatures in the range of 700°C to 1000°C. The influence of the bonded interface on device characteristics of bonded p+n junctions prepared at low temperatures was seen as n-factors larger than 2 at forward bias. A correlation between n-factors and the density of states in the bandgap was found. In hydrophilic samples, the density of voids at the bonded interface was determined mainly in the contacting of the wafer surfaces at room temperature. Compared to hydrophilic samples, hydrophobic samples were held together at a smaller fraction of the area before heat treatment. After the heat treatments, no difference in the density of voids was found
22.
Wall, Göran, 1951-
(author)
Den svenska energi- och materialomsättningen
1982
In: Styrelsen för teknisk utveckling informerar om energiteknik. - Stockholm : Styrelsen för teknisk utveckling. - 0348-7202. ; :3, s. 24-26
Journal article (pop. science, debate, etc.) abstract
För att exemplifiera exergibegreppets betydelse inom resursräkenskap beskrivs här resursomsättningen i det svenska samhället. En mer fullständig beskrivning av detta återfinns i rapporten " The Exergy Conversion in the Swedish Society", rapport nr 80-1, Forskningsgruppen för fysisk Resursteori, Chalmers tekniska högskola, 41296 Göteborg.
23.
Elgered, Gunnar, 1955, et al.
(author)
Measurements of atmospheric water vapor with microwave radiometry
1982
In: Radio Science. - 0048-6604 .- 1944-799X. ; 17:5, s. 1258-1264
Journal article (peer-reviewed) abstract
A dual-channel, ground-based microwave radiometer, working at the frequencies 21.0 and 31.4 GHz, an infrared spectral hygrometer, and radiosondes have been used for comparative measurements of the integrated amount of precipitable water vapor in the atmosphere over a period with zenith water vapor contents varying between 6 and 26 mm. The microwave radiometer was found to give comparable or better formal accuracy than the radiosondes, the absolute accuracy of which is believed to be about 1 mm. The rms difference of the integrated amount of water vapor in the zenith direction measured with the microwave radiometer and with radiosondes was 1.2 mm for all data, and 0.8 mm for a selected group of good weather data. These are lower formal errors than previously reported. It is shown that the simplified relation between the radiometer antenna termperatures and the integrated amount of water vapor in this case contributes with a formal error of about 0.3 mm. It is suggested that mean ground weather data can be used to adapt this relation to other sites and seasons.
24.
25.
Sundberg, Johan, et al.
(author)
Rules for automatized performance of ensemble music
1987
In: STL-QPSR. ; 28:4, s. 057-078
Journal article (other academic/artistic) abstract
Recently developed parts of a computer program are presented that contain a rule system which automatically converts music scores to musical performance, and which, in a sense, can be regarded as a model of a musically gifted player. The development of the rule system has followed the analysis-by-synthesis strategy; various rules have been formulated after having been suggested by a professional string quartet violinist and teacher of ensemble playing. The effects of various rules concerning synchronization and timing and, also, tuning in performance of ensemble music are evaluated by a listening panel of professional musicians. Further support for the notion of melodic charge, previously introduced and playing a prominent rule in the performance rules, is found in a correlation with fine tuning of intervals.
