No description available.

No description available.

Thesis (M.S.)--University of Wisconsin--Madison, 1937. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

We develop and analyze a combination of techniques to improve timing measurement accuracy of systems processing Gaussian pulses distorted by noise. The approach involves M/N detection, integration, and either correlation or threshold timing measurement techniques. The gain of this process is an increase of the detection capabilities of the system: improvement of the detection probability and decrease in false alarm probability, reduction in pulse distortion, and increase of the accuracy of time delay measurements between pulses using either threshold or correlation measurement methods. Each element of the proposed architecture is studied separately, and modeled analytically. As a result, a design method is proposed in order to develop an appropriate solution to any system requiring accurate time delay measurements in noisy environments. This general method is then applied to a real system, and the results in terms of detection improvement and rms timing error of the method meet expectations: the signal to noise ratio (SNR) operating point of the system is lowered by 10dB, and correlation proves to generate 2dB less rms timing error than threshold. / Master of Science

Μεγάλο είναι το ερευνητικό ενδιαφέρον της εκπαιδευτικής κοινότητας για τις αντιλήψεις των μαθητών, που αφορούν στις έννοιες και τα φαινόμενα των φυσικών επιστημών. Αντιλήψεις, οι οποίες συγκροτούνται στη βάση της καθημερινής εμπειρίας και που παρέχουν στο μαθητή τη δυνατότητα να ερμηνεύει τα φαινόμενα του φυσικού κόσμου, συγκροτώντας επεξηγηματικά πρότυπα που, σε πολλές περιπτώσεις, έρχονται σε αντίθεση με τις επιστημονικές θεωρίες, που είναι σήμερα αποδεκτές. Από την άλλη πλευρά, η καινοτομική αντίληψη για τη μάθηση και τη διδασκαλία των φυσικών επιστημών, θεωρεί ότι η ανάπτυξη της επιστημονικής καλλιέργειας των μαθητών και των εκπαιδευτικών, αναφέρεται στη διάδοση των τριών βασικών συνιστωσών της επιστημονικής γνώσης: - της εννοιολογικής συνιστώσας, που συγκροτείται από τις έννοιες των φυσικών επιστημών, - της μεθοδολογικής συνιστώσας, που σχετίζεται με τις διάφορες μεθοδολογικές στρατηγικές και τεχνικές με τις οποίες επιλύονται τα προβλήματα στις φυσικές επιστήμες και - της πολιτισμικής συνιστώσας, που αφορά στο σύνολο των σχέσεων που αναπτύσσουν οι φυσικές επιστήμες με την κοινωνία, όπως για παράδειγμα η σχέση των φυσικών επιστημών με την τεχνολογία, τα προβλήματα και τις εμπειρίες της καθημερινής ζωής, η κατανόηση της ιστορικότητας της επιστημονικής γνώσης κ.α. Η μελέτη του απλού εκκρεμούς, χαρακτηρίζεται από το πλούσιο εννοιολογικό, μεθοδολογικό και πολιτισμικό περιεχόμενο, που αυτό παρουσιάζει. Η μελέτη της κίνησης του, δίνει την ευκαιρία στους μαθητές: - Να έρθουν σε επαφή με θεμελιώδεις επιστημονικές γνώσεις, όπως οι νόμοι της πτώσης και της κίνησης και οι αρχές διατήρησης της ορμής και της ενέργειας. - Να ασκηθούν στη χρήση ουσιαστικών στοιχείων της επιστημονικής έρευνας, όπως η παρατήρηση, η μέτρηση, η συλλογή δεδομένων, ο έλεγχος μεταβλητών και η χρήση διαφόρων μορφών μαθηματικών αναπαραστάσεων. - Να μάθουν σημαντικές όψεις της συσχέτισης της επιστήμης με την κοινωνία, τον πολιτισμό και την τεχνολογία, όπως φανερώνει η χρήση του εκκρεμούς στη χρονομέτρηση, στον προσδιορισμό του γεωγραφικού μήκους, στον καθορισμό μονάδας μέτρησης του μήκους κ.α. Η παρούσα εργασία, έχει ως στόχο τη διερεύνηση των βιωματικών αντιλήψεων των μαθητών της Γ’ Γυμνασίου, που αφορούν στη μέτρηση του χρόνου με τρεις ιστορικούς μηχανισμούς μέτρησης του χρόνου και στη μελέτη της κίνησης του απλού εκκρεμούς. Ειδικότερα, διερευνώνται οι αντιλήψεις των μαθητών που σχετίζονται με την εννοιολογική, τη μεθοδολογική και την πολιτισμική συνιστώσα της γνώσης που σχετίζεται με την ισόχρονη κίνηση του απλού εκκρεμούς. Στο πρώτο κεφάλαιο, παρουσιάζεται το θεωρητικό πλαίσιο της έρευνας, που απαρτίζεται από: - τη γνώση αναφοράς, δηλαδή το ιστορικό πρόβλημα της μέτρησης του χρόνου και τη σχέση του με το απλό εκκρεμές, - τις αντιλήψεις των μαθητών για το απλό εκκρεμές και - τους στόχους της έρευνας. Στο δεύτερο κεφάλαιο, παρουσιάζεται η μεθοδολογική προβληματική της μελέτης, που αφορά: - στις στρατηγικές και - στο δείγμα της έρευνας. Στο τρίτο κεφάλαιο, παρουσιάζονται τα αποτελέσματα της ανάλυσης των δεδομένων. Τέλος, στο τέταρτο κεφάλαιο, διατυπώνονται τα συμπεράσματα της μελέτης των αντιλήψεων των μαθητών, στη βάση των ερευνητικών στόχων και συζητούνται οι ενδεχόμενες επιπτώσεις τους στη διδασκαλία του απλού εκκρεμούς στην εκπαιδευτική βαθμίδα του γυμνασίου, καθώς και μία πρόταση επέκτασης της έρευνας. / -

This thesis describes the construction of an apparatus to measure reverberation time.

No description available.

No description available.

Este trabalho apresenta a aplicação de uma metodologia para estudos de postos de trabalho com o objetivo de reduzir desperdícios, aplicar melhorias de layout e consequentemente melhora da ergonomia de um posto de trabalho de uma indústria do ramo automotivo, visando o diagnóstico do processo em questão, encontrando assim, oportunidades para melhoria do mesmo. Para realizar este diagnóstico e identificar as melhorias pretendidas foi utilizada a ferramenta de análise de tempo MTM (Methods-Time Measurement), técnicas de balanceamento, ergonomia e estudo de layout. Atualmente há muitas empresas no mundo que utilizam o MTM (Methods-Time Measurement), que é um sistema de tempos pré-determinados. A eliminação dos desperdícios com a finalidade da redução de tempo é necessária para o aumento da produção que será aplicado em 2012, que tem como objetivo a passagem de 29 veículos por hora para 40 veículos por hora na linha de montagem. Para o estudo de caso, foram selecionados três postos, os quais são nomeados segundo suas operações principais. O primeiro deles, Filme CAPOT, compreende a colocação de filme protetor sobre o capot do veículo na saída da linha de montagem. O segundo, Filme TETO, corresponde à colocação do mesmo filme sobre o teto do veículo. Já o Posto ECOM é onde ocorre a liberação do veículo para comercialização. Utilizando a análise de posto com as ferramentas já listadas, foi possível diminuir o tempo necessário ao operador para que mesmo realize suas atividades e assim aumentar a capacidade produtiva da empresa em 48,9%, ou seja, passa-se de 31,1 para 46,3 veículos por hora. A ergonomia do espaço de trabalho teve sua avaliação global modificada nos postos de colocação de filme de proteção no CAPOT e TETO em função da modificação do layout dos postos propiciando aos operadores menores deslocamentos e posturas de trabalho mais ergonômicas que estão abordadas no corpo do trabalho. Temse também o ganho relacionado ao espaço físico, os três postos utilizavam, juntos, 300,9m do prédio da empresa já na situação proposta necessita-se apenas de 142,6m, uma redução de 52,6%. / This paper presents the application of a methodology for studies of work stations in order to reduce waste, implement improvements to layout and consequently improves the ergonomics of a work station at automotive industry, for the diagnosis of the case in question, finding opportunities for improvement. To make this diagnosis and identify the intended improvements was used a toll for analysis of time called MTM (Methods-Time Measurement), balancing techniques, ergonomics and layout study. Currently there are many companies worldwide that use MTM (Methods-Time Measurement), which is a system of predetermined times. The elimination of waste for the purpose of reducing the time is required for the increased production to be applied in 2012, which intends the passage of 29 vehicles per hour for 40 vehicles per hour on the assembly line. For the case study, we selected three stations, which are named according to their main operations. The first, Filme CAPOT, comprising placing protective film on the top of the vehicle off the assembly line. The second Filme TETO corresponds to placing the same film on the ceiling of the vehicle. Finally the station ECOM is where occurs the release of the vehicle for sale. Using the work station analysis with the tools already listed, it was possible to reduce the time required for the operator to perform the same activities and increase the companys production capacity in 48.9%, from 31.1 to 46.3 vehicles per hour. The ergonomics of the workspace had his overall evaluation changed at the placing protective film on CAPOT and TETO stations, because the modifying the layout of the stations enabling operators to smaller displacements and more ergonomic working postures that are addressed in the body of the work. There is also the gain related to the physical space, the three stations used together 300.9 m of the companys building, and after proposed situation they needs only 142.6 m, a decrease of 52.6%.

The effect of the spatial distribution of a radioactive source on timing measurements has been investigated with particular consideration toward the focal plane of recoil separators. The work conducted during this thesis is a precursor to understand the magnitude of such effects for the upcoming fast timing array (FATIMA) at FAIR. An experiment was undertaken at the University of Jyvaskyla using the K130 cyclotron to accelerate a 36-Ar beam to 190 MeV, directed onto a 106-Cd target, to produce recoils of 138-Gd and 136-Sm via fusion-evaporation reactions. Recoils directed using RITU to the focal-plane DSSSD of GREAT were distributed over the majority of the 124-mm by 40-mm extension of the DSSSD. A new array consisting of eight lanthanum bromide detectors was used to measure the time between coincident prompt-gamma rays emitted following the de-excitation of isomeric recoil states implanted into the DSSSD. Lifetimes were measured to be 213(20) ps and 200(100) ps for the first-excited 2+ states in 138-Gd and 136-Sm, respectively. Positional information, extracted from the DSSSD, was used to correct for the difference in the time-of-flight of gamma rays as they travelled from the implantation position to the lanthanum bromide detectors. When accounted for, the lifetimes were remeasured to be 217(20) ps and 210(90) ps, respectively, showing no significant change in value or error. A method of quantifying the increase in uncertainty of a lifetime measurement due to the spatial distribution of the source and the position of the surrounding detectors, supported by simulation, has been provided to explain these observations. A new technique for extracting the time-walk from each of the CFDs in a multi-detector array has been presented. The new technique offers a reduced complexity in calculations by accounting for the correlated time-walks present in time measurements from different detector-pairs sharing a common CFD. Work towards a technique for extracting lifetimes from time data has been presented. Dubbed the Symmetrised-Convolution Lifetime Measurement (SCLM) method, this technique essentially applies a model-dependent convolution of the prompt-response with nuclear exponential decay on both time spectra, obtained by inverting the start and stop conditions of a TAC, simultaneously and draws parallels to the Mirror Symmetric Centroid Difference method.