On the polishing of glass, particularly the precision polishing of optical surfaces

In this survey, the views on the mechanism of the polishing of glass to be found in the literature are only dealt with briefly, because extensive summarizing evaluations of reports dealing with the problem are available. The main objective of this paper is the investigation of the causes of hitherto differing views on the processes occurring during the polishing of glass, despite the extensive literature which exists in over 500 publications. The causes for the differing interpretations of the polishing mechanisms result from an incorrect evaluation of the properties of the polishing compounds and of the polishing parameters during precision polishing. Therefrom and from the author's long-term investigations of the properties of model polishing compounds and of the polishing processes with these model polishing compounds under optical production conditions a generally valid theory of the polishing of optical media was developed. This idea — named "tribochemical friction-wear polishing theory" — is totally different from hypotheses presented up to now. The present paper tries to verify the correctness of the new theory

PIN Modulator and Attenuator - laboratory experiments

Účelem tohoto semestrálního projektu je vytvoření koncepce laboratorní úlohy Amplitudový modulátor a zeslabovač s diodou PIN, jež by byla alternativou úlohy měřené v předmětu BSES na jiném vzorku. Pro tuto laboratorní práci byl zvolen amplitudový modulátor firmy Hewlett Packard HP-8732A pro své výhodné vlastnosti, zejména jednoduchou manipulaci vzhledem ke koaxiálnímu připojení mikrovlnného signálu. Práce obsahuje jednak teoretické shrnutí principů činnosti diody PIN, jednak seznamuje s jejich aplikacemi, zejména v amplitudových modulátorech a řízených odporových zeslabovačích. Dále jsou zde zdokumentovány výsledky jednotlivých měření sloužící pro zjištění, případně ověření vlastností modulátoru HP-8732A. Nejpodstatnější částí je vlastní návrh několika bodů měření spolu s pokyny pro ovládání přístrojů, návrh formuláře protokolu o měření a jeho vzorově vyplněná verze. Posledním bodem této práce je idea demonstrace možného využití daného modulátoru ve stabilizátoru výkonu.Purpose of this bachelor’s thesis is making conception of laboratory work “Amplitude modulator and attenuator with diode PIN“, what was alternative work measure in subject BSES on other sample. For this laboratory work was chosen amplitude modulator of company Hewlett Packard HP - 8732A for its advantage properties, especially easy manipulation with respect to coaxial connection of microwave signal. Work contains partly theoretical summary principles activity of diode PIN, partly it introduce their applications, especially in amplitude modulators directed of reflex reducer. Next there are documented results of single measures servant for ensure check needed properties modulator HP – 8732A. The main part of this work is proposal several points of measure together with introductions for operating devices, proposal form of measure protocol and it’s example. Final point is idea of possibility usage this modulator in power stabilizer.

Dissertation on the polishing of spherical objects by S. Hambücker - Α critical review

[no abstract available

Properties of polishing media for precision optics

The first theory concerning the pohshing of glass, which viewed polishing as an extension of the grinding process with finer abrasives, and the flow theory of Beilby, both stipulate purely hypothetically that the polishing grains should have a very high hardness. This hypothesis of high hardness of the polishing grains was so strongly supported by Smekal and Brüche in the 40's and 50's and by other scientists in the following years that it became dogma, i.e., a claim without proof, and has remained virtually universally accepted to this day. The results of the investigations of the present author have shown, however, that first, extra lattice defects in the crystalline oxides used as polishing agents are the primary characteristics that are responsible for the gripping of the grains during polishing and second, the hardness of the grains of the polishing agent must be lower than that of the material which is being polished. By and large these results have been ignored in the literature, because they are in Opposition to the dogma that the polishing agent must have a high hardness. Clear proof is presented in this paper that disproves the generally accepted hypothesis that polishing can be done with very fine grinding powder, and that the polishing agent must be harder than the glass which is to be polished. The properties of polishing agents for use in polishing for precision optics will be described on the basis of the theory of polishing agents containing lattice defects

Mobile Communication Networks and Digital Television Broadcasting Systems in the Same Frequency Bands – Advanced Co-Existence Scenarios

The increasing demand for wireless multimedia services provided by modern communication systems with stable services is a key feature of advanced markets. On the other hand, these systems can many times operate in a neighboring or in the same frequency bands. Therefore, numerous unwanted co-existence scenarios can occur. The aim of this paper is to summarize our results which were achieved during exploration and measurement of the co-existences between still used and upcoming mobile networks (from GSM to LTE) and digital terrestrial television broadcasting (DVB) systems. For all of these measurements and their evaluation universal measurement testbed has been proposed and used. Results presented in this paper are a significant part of our activities in work package WP5 in the ENIAC JU project “Agile RF Transceivers and Front-Ends for Future Smart Multi-Standard Communications Applications (ARTEMOS)”

Macroinvertebrate community of ecology of lowland, subtropical streams in Louisiana

Freshwater ecosystems, particularly streams and rivers, have been the subject of prodigious research. Unfortunately, in comparison to neighboring regions, the Gulf of Mexico coastal plain has not received as much attention. Therefore, I collected data on the macroinvertebrates of these streams to begin the understanding of the relationships between community structure and environmental characteristics. In contrast to the hypothesized ancestral streams of these macroinvertebrates, coastal plain streams are commonly devoid of rocks leaving only woody debris as usable hard substrates and are typically lower in dissolved oxygen. I examined habitat selection by colonization of woody debris with large and small surface areas. Secondly, given a similar surface area, I examined colonization in different levels of dissolved oxygen. Concurrently, I conducted biota and habitat surveys in three streams over four periods from August 2002 until April 2004 to collect baseline data for future investigations. The survey data included macroinvertebrate collections, microbial population estimations, water chemistry, and habitat descriptions. Finally, over the same time period, I collected macroinvertebrate, microbial, water chemistry, and habitat data in a stream with a potentially strong biotic disturbance, feral swine (Sus scrofa). All data were examined with appropriate multivariate statistics. The in-stream experiment suggested similar colonization of both sizes of woody debris for 20 of 21 taxa examined. Some potential high and low dissolved oxygen specialization was detected in the experiment, however, many macroinvertebrates (37%) appeared to be dissolved oxygen generalists. Further, survey data suggested more than 50% of collected macroinvertebrates also may be generalists with regard to other abiotic factors, but did demonstrate some affinity for woody debris. The single stream biotic disturbance appeared to significantly alter the macroinvertebrate community with a potential shift in favor of collecting organisms against scraping organisms. Therefore, in contrast with other regions, I suggest that coastal plain macroinvertebrates are tolerant to many abiotic factors, but are intolerant of some biotic disturbances

Testing QoE in Different 3D HDTV Technologies

The three dimensional (3D) display technology has started flooding the consumer television market. There is a number of different systems available with different marketing strategies and different advertised advantages. The main goal of the experiment described in this paper is to compare the systems in terms of achievable Quality of Experience (QoE) in different situations. The display systems considered are the liquid crystal display using polarized light and passive lightweight glasses for the separation of the left- and right-eye images, a plasma display with time multiplexed images and active shutter glasses and a projection system with time multiplexed images and active shutter glasses. As no standardized test methodology has been defined for testing of stereoscopic systems, we develop our own approach to testing different aspects of QoE on different systems without reference using semantic differential scales. We present an analysis of scores with respect to different phenomena under study and define which of the tested aspects can really express a difference in the performance of the considered display technologies

Reducing Falls on the Neurovascular Unit

https://digitalcommons.psjhealth.org/stvincent-bootcamp/1015/thumbnail.jp

La gramática en los trastornos de la comunicación y el lenguaje

En esta comunicación, expondremos, dentro de una perspectiva gramatical, ciertos objetivos de investigación acerca de la adquisición / aprendizaje de las categorías funcionales en adolescentes sordos y en un joven con diagnóstico de Trastorno Generalizado del Desarrollo (TGD). Comenzaremos por la cuestión de la concordancia entre sujeto y predicado, y la identificación de la referencia manifestada en los pronombres. Partiremos de la hipótesis de que la jerarquía de instigadores naturales (Moure 2001) incide en la identificación exitosa de los referentes; y de la idea de que existe una relación proporcional entre la menor información codificada léxicamente y la menor proximidad sintáctica con el verbo con el que concuerda, por un lado, y el número de los fallos en la interpretación, por otro. En efecto, se observa que la dificultad en el procesamiento de la información gramatical (más abstracta que la de las clases léxicas y, además, expresada, a través de rasgos de baja sustancia fónica -como los de flexión-) resulta un indicio contundente del déficit morfosintáctico, el que sumado a otros marcadores psicolingüísticos, colabora en la detección del fracaso en el desarrollo lingüístico (Buiza Navarrete et al 2004