No description available.

Ahlberg Cameras is a company that manufactures advanced camera systems and inspection equipment for the nuclear industry. Every nuclear plant shuts down their reactors approximately every 18 months to perform visual inspections of the vessels to find cracks and other damage. The company has received a request from Electric Power Research Institute (EPRI) to develop a distance meter that will operate in the reactor vessel, placed in an inspection camera. The device should measure the distance between the camera and an object, and the angle between them. The measurement is performed in air and underwater and the device has therefore a requirement to be waterproof and radiation tolerant.   This thesis work has studied different possible technologies and technically excluded the ones that are not suitable for the intended application. A large part of the study has been about whether sound or light is a good enough source to use in the different technologies. The study has excluded to use sound mainly because the reflection back to the receiver at large angles becomes too weak. The choice of technology stands between structured light and a self-designed trigonometry technology, both using lasers. Tests have been made to determine if laser light underwater can be observed by the camera and the results indicates that lasers work well enough for this kind of application. Further in-depth studies into the sources of errors and measurement accuracy are needed for determining which of the two technologies is the most suitable.

The ability to visualize a solution space can be very beneficial, and it is generally accepted that the objective of visualization is to aid researchers in gathering insight. However, insight cannot be gathered effectively if the source data is misrepresented. This dissertation begins by demonstrating that the adaptive landscape visualization in widespread usage frequently misrepresents the neighborhood structure of genotypic space and, consequently, will mislead users about the manner in which solution space is traversed by the genetic algorithm. Bernhard Riemann, the father of topology, explicitly noted that a measurement of the distance between entities should represent the manner in which one can be brought towards the other. Thus, the commonly used Hamming distance, for example, is not representative of traversals of genotypic space by the genetic algorithm – a representative measure must include consideration for both mutation and recombination. This dissertation separately explores the properties that mutational and recombinational distances should have, and ultimately establishes a measure that is representative of the traversals made by both operators simultaneously. It follows that these measures can be used to enhance the adaptive landscape, by minimizing the discrepancy between the interpoint distances in genotypic space and the interpoint distances in the two-dimensional representation from which the landscape is extruded. This research also establishes a methodology for evaluating measures defining neighbourhood structures that are purportedly representative of traversals of genotypic space, by comparing them against an empirically generated norm. Through this approach it is conclusively demonstrated that the Hamming distance between genotypes is less representative than the proposed measures, and should not be used to define the neighbourhood structure from which visualizations would be constructed. While the proposed measures do not distort the data or otherwise mislead the user, they do require a significant computational expense. Fortunately, the choice to use these measures is always made at the discretion of the user, with additional costs incurred when accuracy and representativity are of paramount importance. These measures will ultimately find further application in population diversity measurement, cluster analysis, and any other task where the representativity of the neighborhood structure of the genotypic space is vital.

The Pedestrian Detection System (PDS) has become a significant area of research designed to protect pedestrians. Despite the huge number of research work, the most current PDSs are designed to detect pedestrians without knowing their distances from cars. In fact, a priori knowledge of the distance between a car and pedestrian allows this system to make the appropriate decision in order to avoid collisions. Typical methods of distance measurement require additional equipment (e.g., Radars) which, unfortunately, cannot identify objects. Moreover, traditional stereo-vision methods have poor precision in long-range conditions. In this thesis, we use the keypoint-based feature extraction method to generate the parallax in a binocular vision system in order to measure a detectable object; this is used instead of a disparity map. Our method enhances the tolerance to instability of a moving vehicle; and, it also enables binocular measurement systems to be equipped with a zoom lens and to have greater distance between cameras. In addition, we designed a crossover re-detection and tracking method in order to reinforce the robustness of the system (one camera helps the other reduce detection errors). Our system is able to measure the distance between cars and pedestrians; and, it can also be used efficiently to measure the distance between cars and other objects such as Traffic signs or animals. Through a real word experiment, the system shows a 7.5% margin of error in outdoor and long-range conditions.

Auf der von der Hochschule für Technik und Wirtschaft Dresden betriebene EDM-Basislinie im Großen Garten in Dresden werden regelmäßig die Sollstrecken überprüft. Die Ergebnisse deuten auf Punktbewegungen hin. Durch Vergleiche zweier Epochen wird versucht, solche Punktbewegungen statistisch nachzuweisen, sowohl mittels statistischer Hypothesentests, als auch mit einem Informationskriterium. Punktbewegungen von bis zu 0,25 mm/a wurden geschätzt. Über die Ursachen wird noch spekuliert.

No description available.

A distance measurement by means of phase is used in a scheme to locate a transmitter. The system consists of three antennas. There is a transmitter, that in a sense acts as a target, in terms of radar concepts. Two receivers are used to determine the distance needed to find the position of the transmitter in the 2D plane. The software LabVIEW is used in this study. The cable lengths are adapted to the measurement.

The structure and function of RNA molecules are dependent on RNA-metal ion interactions in both diffusive and direct ways. Structural information for RNA has been obtained using various biophysical and biochemical methods. In this study, using site-directed spin labeling (SDSL) and EPR spectroscopy, distances in RNA duplexes, TAR RNA, and the hammerhead ribozyme have been measured to investigate RNA structures. Kinetic measurements have been performed in the extended hammerhead ribozyme to correlate the catalytic function with metal dependent ribozyme folding. As a basic model system for distance measurements, inter-spin distances in RNA duplexes with spin labels at various positions are measured using SDSL with continuous EPR and a Fourier deconvolution method. Divalent metal-ion dependent TAR RNA folding from bent to extended conformers is monitored by measuring inter-spin distances near the bulge region. In order to investigate a proposed loop-loop interaction in the extended hammerhead ribozyme which significantly enhances the ribozyme activity, distance measurements, dynamics studies, and kinetics measurements have been performed. We have introduced PELDOR long-distance measurements in order to investigate metal dependent folding of the hammerhead ribozyme. The dynamics of the spin labels attached to the hammerhead ribozyme with increasing mono- and divalent metal ion concentrations are monitored using CW EPR spectroscopy at room temperature. EPR data show that a loop-loop interaction occurs near the U1.6 nucleotide, and that in 0.1 M NaCl the docking occurs at submillimolar Mg2+ concentrations ([Mg2+]1/2, docking = ~ 0.7 mM). Kinetics measurements show that the hammerhead ribozyme requires high concentration of Mg2+ for the maximum cleavage activity ([Mg2+]1/2, cleavage = ~ 90 mM).

The structure and function of RNA molecules are dependent on RNA-metal ion interactions in both diffusive and direct ways. Structural information for RNA has been obtained using various biophysical and biochemical methods. In this study, using site-directed spin labeling (SDSL) and EPR spectroscopy, distances in RNA duplexes, TAR RNA, and the hammerhead ribozyme have been measured to investigate RNA structures. Kinetic measurements have been performed in the extended hammerhead ribozyme to correlate the catalytic function with metal dependent ribozyme folding. As a basic model system for distance measurements, inter-spin distances in RNA duplexes with spin labels at various positions are measured using SDSL with continuous EPR and a Fourier deconvolution method. Divalent metal-ion dependent TAR RNA folding from bent to extended conformers is monitored by measuring inter-spin distances near the bulge region. In order to investigate a proposed loop-loop interaction in the extended hammerhead ribozyme which significantly enhances the ribozyme activity, distance measurements, dynamics studies, and kinetics measurements have been performed. We have introduced PELDOR long-distance measurements in order to investigate metal dependent folding of the hammerhead ribozyme. The dynamics of the spin labels attached to the hammerhead ribozyme with increasing mono- and divalent metal ion concentrations are monitored using CW EPR spectroscopy at room temperature. EPR data show that a loop-loop interaction occurs near the U1.6 nucleotide, and that in 0.1 M NaCl the docking occurs at submillimolar Mg2+ concentrations ([Mg2+]1/2, docking = ~ 0.7 mM). Kinetics measurements show that the hammerhead ribozyme requires high concentration of Mg2+ for the maximum cleavage activity ([Mg2+]1/2, cleavage = ~ 90 mM).

Abstract The main aim of this work was to design CMOS receiver channels for the integrated receiver chip of a pulsed time-of-flight (TOF) laser rangefinder. The chip includes both the receiver channel and the time-to-digital converter (TDC) in a single die, thus increasing the level of integration of the system, with the corresponding advantages of a cheaper price and lower power consumption, for example. Receiver channels with both linear and leading edge timing discriminator schemes were investigated. In general the receiver channel consists of a preamplifier, a postamplifier and a timing comparator. Since a large systematic timing error may occur due to high variation in the amplitude of the received echo, a leading edge timing discriminator scheme with time domain walk error compensation is proposed here, making use of the TDC already available in the chip to measure the slew rate of the pulse and using that information to evaluate the timing error. This compensation scheme benefits from the fact that compensation can be continued even though the signal is clipped in the amplitude domain, because the slew rate continues to increase even then. The receiver channel with leading edge detection and time domain walk error compensation achieved a compensated timing walk error of ±4.5 mm within a dynamic range of more than 1:10000. The standard deviation in single shot precision was less than 25 mm with an SNR of more than 20. The usability of the receiver channel in pulsed TOF laser rangefinders was verified by making actual time-of-flight measurements on a calibrated measurement track. The linearity of the receiver chip was better than ±5 mm in a measurement range from 3 m to 21 m, with the dynamic range of the receiver channel reaching more than 1:2000. An integrated CMOS laser diode pulser was also demonstrated to prove its functionality for generating ampere-scale peak current pulses through a low ohmic load and a laser diode. The CMOS pulser achieved a peak current pulse with the amplitude of ~1 A, an optical pulse width of ~2.5 ns and a rise time of ~1 ns with a 5 V power supply. / Tiivistelmä Työn ensisijaisena tavoitteena oli suunnitella CMOS-vastaanottimia valopulssin kulkuajan mittaukseen perustuvan lasertutkan integroituun vastaanotinpiiriin. Vastaanotinpiiri sisältää sekä vastaanotinkanavan että aika-digitaalimuuntimen yhdellä integroidulla sirulla. Tällöin systeemin integrointiastetta saadaan kasvatettua, mikä merkitsee esimerkiksi halvempaa hintaa ja pienempää tehon kulutusta. Työssä on tutkittu vastaanotinkanavia, jotka käyttävät joko lineaariseen ilmaisuun tai etureunailmaisuun perustuvaa ajoitusilmaisutekniikkaa. Yleisesti vastaanotinkanava sisältää esivahvistimen, jälkivahvistimen ja ajoituskomparaattorin. Vastaanotetun signaalin tason voimakas vaihtelu saattaa aiheuttaa suuren systemaattisen virheen etureunailmaisuun perustuvassa ajoitusilmaisussa. Tässä työssä on esitetty etureunailmaisua käyttävä ajoitusilmaisin, jossa syntyvää ajoitusvirhettä voidaan korjata mittaamalla pulssin nousunopeutta aika-digitaalimuuntimella, joka on integroitu samalle sirulle. Aikatasossa tapahtuvan virheenkorjauksen etuna on mahdollisuus jatkaa virheenkorjausta amplituditasossa tapahtuvan signaalin leikkautumisen jälkeenkin, koska signaalin nousunopeus kasvaa leikkaantumisesta huolimatta. Etureunailmaisua käyttävällä vastaanotinkanavalla, jossa ajoitusvirhettä korjattiin pulssin nousunopeutta mittaamalla, saavutettiin ±4,5 mm ajoitusvirhe 1:10000 dynaamisella alueella. Kertamittaustarkkuuden keskihajonta oli vähemmän kuin 25 mm, kun signaalikohinasuhde oli enemmän kuin 20. Vastaanotinkanavan käytettävyys osana lasertutkaa todettiin tekemällä tutkamittauksia kalibroidulla mittaradalla. Mittauksissa saavutettu lineaarisuus oli ±5 mm mittausalueen vaihdellessa 3 metristä 21 metriin ja signaalin dynamiikan ollessa enemmän kuin 1:2000. Lisäksi työssä esitellään integroitu CMOS-pulssitin, joka pystyy tuottamaan ampeeri-luokan virtapulsseja laserdiodiin. CMOS-pulssittimella voitiin tuottaa 5 V käyttöjännitteellä ~1 A virtapulsseja optisen pulssin leveyden ja nousuajan ollessa ~2,5 ns ja ~1 ns.