Teses / dissertações sobre o tema "Time interval measurement"

Smart watches in future will have smart wristband. This work analyses properties of new developed capacitive wristband sensor that measures ballistocardiogram (BCG) from single point on the wrist. In addition, it considers applications of this sensor to monitoring heart rate variability. Another application is in estimating changes (trend) in systolic blood pressure continuously when combined with lead one electrocardiogram (ECG). BP is one of the vital signs that indicates the health condition. It is commonly measured by cuff-based monitor using either auscultatory or oscillometric method. Cuff-based BP monitor is not portable and unable to measure BP continuously which means it is difficult to attach BP monitoring function on a wearable device. Significant research is conducted in estimating BP from pulse transit time (PTT) mathematically which would enable the cuffless BP measurement. In this work, a new time reference, RJ interval, which is the time delay between ECG and BCG signal peaks was tested whether it can be used as a surrogate of PTT in cuffless BP estimation. Based on the study done on 10 healthy people, it was shown that RJ intervals can be useful in evaluating trends of systolic blood pressure.

As further advances are made in semiconductor manufacturing technology the performance of circuits is continuously increasing. Unfortunately, as the technology node descends deeper into the nanometre region, achieving the potential performance gain is becoming more of a challenge; due not only to the effects of process variation but also to the reduced timing margins between signals within the circuit creating timing problems. Production Standard Automatic Test Equipment (ATE) is incapable of performing internal timing measurements due, first to the lack of accessibility and second to the overall timing accuracy of the tester which is grossly inadequate. To address these issue ‘on-chip’ time measurement circuits have been developed in a similar way that built in self-test (BIST) evolved for ‘on-chip’ logic testing. This thesis describes the design and analysis of three time amplifier circuits. The analysis undertaken considers the operational aspects related to gain and input dynamic range, together with the robustness of the circuits to the effects of process, voltage and temperature (PVT) variations. The design which had the best overall performance was subsequently compared to a benchmark design, which used the ‘buffer delay offset’ technique for time amplification, and showed a marked 6.5 times improvement on the dynamic range extending this from 40 ps to 300ps. The new design was also more robust to the effects of PVT variations. The new time amplifier design was further developed to include an adjustable gain capability which could be varied in steps of approximately 7.5 from 4 to 117. The time amplifier was then connected to a 32-stage tapped delay line to create a reconfigurable time measurement circuit with an adjustable resolution range from 15 down to 0.5 ps and a dynamic range from 480 down to 16 ps depending upon the gain setting. The overall footprint of the measurement circuit, together with its calibration module occupies an area of 0.026 mm2 The final circuit, overall, satisfied the main design criteria for ‘on-chip’ time measurement circuitry, namely, it has a wide dynamic range, high resolution, robust to the effects of PVT and has a small area overhead.

Abstract The aim of this thesis was to develop time-to-digital converters (TDC) for the integrated receiver of a pulsed time-of-flight (TOF) laser rangefinder aiming at cm-level accuracy over an input range of 10 m – 15 m. A simple structure, a high integration level and low power consumption are the desired features for such a TDC. From the pulsed TOF laser rangefinder point of view an integrated receiver consisting of both the TDC and the receiver channel on the same die offers the possibility of manufacturing these laser rangefinders with a high integration level and at a low price to fulfil the needs of mass industrial markets. The heart of the TDC is a CMOS ring oscillator, the clock frequency of which is used to calculate the full clock cycles between timing signals, the positions of the timing signals inside the clock period being determined by storing the state of the phase of the ring oscillator for each timing signal. This will improve the resolution of the TDC. Also, additional delay lines are used to generate multiple timing signals, each having a time difference of a fraction of that of the ring oscillator. This will further improve the resolution of the whole TDC. To achieve stable results regardless of temperature and supply voltage variations, the TDC is locked to an on-chip reference voltage, or the resolution of the TDC is calibrated before the actual time interval measurement. The systematic walk error in the receiver channel caused by amplitude variation in the received pulse is compensated for by the TDC measuring the slew rate of the received pulse. This time domain compensation method is not affected by the low supply voltage range of modern CMOS technologies. Three TDC prototypes were tested. A single-shot precision standard deviation of 16 ps (2.4 mm) and a power consumption of 5.3 mW/channel were achieved at best over an input range of 100 ns (15 m). The temperature drifts of an on-chip voltage reference-locked TDC and a TDC based on the calibration method were 90 ppm/°C and 0.27 ps/°C, respectively. The results also showed that a pulsed TOF laser rangefinder with cm-level accuracy over a 0 – 15 m input range can be realized using the integrated receiver with the time domain walk error compensation described here
Tiivistelmä Väitöskirjatyön tavoitteena oli kehittää aika-digitaalimuunninrakenteita valopulssin kulkuajan mittaukseen perustuvan lasertutkan integroituun vastaanottimeen. Tavoitteena oli saavuttaa senttimetriluokan tarkkuus 10 m – 15 m mittausalueella koko lasertutkan osalta. Aika-digitaalimuuntimelta vaaditaan yksinkertaista rakennetta, korkeaa integroimisastetta ja matalaa tehonkulutusta. Integroitu vastaanotin sisältää sekä aika-digitaalimuuntimen että vastaanotinkanavan ja tarjoaa mahdollisuuden korkeasti integroidun lasertutkan valmistukseen halvalla teollisuuden massamarkkinoiden tarpeisiin. Aika-digitaalimuuntimen ytimenä toimii monivaiheinen CMOS-rengasoskillaattori. Aika-digitaalimuunnos perustuu rengasoskillaattorin täysien kellojaksojen laskentaan laskurilla ajoitussignaalien välillä. Lisäksi rengasoskillaatorin jokaisesta vaiheesta otetaan näyte ajoitussignaaleilla niiden paikkojen määrittämiseksi kellojakson sisällä, jolloin aika-digitaalimuuntimen erottelutarkkuutta saadaan parannettua. Erottelutarkkuutta parannetaan lisää viivästämällä ajoitussignaaleja viive-elementeillä ja muodostamalla näin useita erillisiä ajoitussignaaleja, joiden väliset viive-erot ovat murto-osa rengasoskillaattorin viive-elementin viiveestä. Aika-digitaalimuunnin stabiloidaan käyttöjännite- ja lämpötilavaihteluja vastaan lukitsemalla se integroidun piirin sisäiseen jännitereferenssiin, tai sen erottelutarkkuus määritetään ennen varsinaista aikavälinmittausta erillisellä kalibrointimittauksella. Vastaanotetun valopulssin amplitudivaihtelun aiheuttama systemaattinen ajoitusvirhe integroidussa vastaanotinkanavassa kompensoidaan mittaamalla vastaanotetun valopulssin nousunopeus aika-digitaalimuuntimella. Tällainen aikatasoon perustuva kompensointimetodi on myös suorituskykyinen nykyisissä matalakäyttöjännitteisissä CMOS-teknologioissa. Työssä valmistettiin ja testattiin kolme aika-digitaalimuunninprototyyppiä. Muuntimien kertamittaustarkkuuden keskihajonta oli parhaimmillaan 16 ps (2,4 mm) ja tehonkulutus alle 5,3 mW/kanava mittausetäisyyden olessa alle 100 ns (15 m). Sisäiseen jännitereferenssiin lukitun aika-digitaalimuuntimen lämpötilariippuvuudeksi mitattiin 90 ppm/°C ja kalibrointimenetelmällä saavutettiin 0,27 ps/°C lämpötilariipuvuus. Työssä saavutetut tulokset osoittavat lisäksi, että valopulssin kulkuajan mittaukseen perustuvalla lasertutkalla on saavutettavissa senttimetriluokan tarkkuus 0 – 15 m mittausalueella käyttämällä tässä työssä esitettyä integroitua vastaanotinta ja aikatason ajoitusvirhekompensointia

Abstract The aim of this work was to develop time-to-digital converters(TDC) with a wide measurement range of several hundred microseconds and with a measurement precision of a few picoseconds. Because of these requirements, the focus of this work was mainly on TDC architectures based on the Nutt interpolation method, which has several advantages when a long measurement range is a requirement. Compared to conventional data converters the characteristics of a Nutt TDC differ significantly when, for example, quantization errors and linearity errors are considered. In this thesis, the operating principle of a Nutt TDC is analysed and, in particular, the effects of reference clock instabilities are studied giving new insight how the different phase noise processes can be reliably translated into time interval jitter, and how these affect the measurement precision when very long time intervals are measured. Furthermore, these analytical results are confirmed by measurements conducted with a long-range TDC designed as part of this work. Two long-range TDCs have been designed, each based on different interpolator architectures. The first TDC utilises discrete component time-to-voltage converters(TVC) as interpolators. Other key functionality is implemented on an FPGA. The interpolators use Miller integrators to improve the linearity and the single-shot precision of the converter. The TDC has a nominal measurement range of 84ms and it achieves a single-shot precision of 2ps for time intervals shorter than 2ms, after which the precision starts to deteriorate due to the phase noise of the reference clock. In addition to the discrete TDC, an integrated long-range CMOS TDC has been designed with 0.35μm technology. Instead of TVCs, this TDC features cyclic/algorithmic interpolators, which are based on switched-frequency ring oscillators(SRO). The frequency switching is used as a mechanism to amplify quantization error, a key functionality required by any cyclic or a pipeline converter. The interpolators are combined with a 16-bit main counter giving a total range of 327μs. The RMS single-shot precision of the TDC is 4.2ps without any nonlinearity compensation. Furthermore, a calibration functionality implemented partially on-chip ensures that the accuracy of the TDC varies only ±2.5ps in a temperature range of -30C to 70C. Although implemented with fairly old technology, the interpolators’ effective linear range and precision represent state-of-the-art performance
Tiivistelmä Tämän työn tavoitteena oli kehittää aika-digitaalimuuntia (TDC), joilla on laaja satojen mikrosekuntien mittausalue ja muutaman pikosekunnin kertamittaustarkkuus. Näistä vaatimuksista johtuen tässä työssä keskitytään pääasiassa Nuttin interpolointimenetelmään perustuviin TDC-arkkitehtuureihin. Verrattuna tavanomaisiin datamuuntimiin, Nutt TDC:n toiminta poikkeaa merkittävästi, kun tarkastellaan kvantisointi- ja lineaarisuusvirhettä. Tässä väitöskirjatyössä Nuttin menetelmään perustavan TDC:n toiminta analysoidaan, jonka yhteydessä tutkitaan erityisesti referenssioskillaattorin epästabiilisuuksien vaikutusta mittausepävarmuuteen. Tämän pohjalta vaihekohinan eri kohinaprosessit voidaan luotettavasti muuntaa taajuustason kohinatiheysmittauksista aika-tasossa kuvattavaksi aikavälijitteriksi. Nämä teoreettiset tulokset ovat varmistettu yhdellä osana tätä työtä suunnitellulla pitkän kantaman TDC:llä. Teoreettisen tarkastelun lisäksi kaksi pitkän kantaman TDC:tä on suunniteltu, toteutettu ja testattu. Ensimmäinen näistä perustuu erilliskomponenteilla toteutettuun aika-jännitemuunnokseen (TVC) pohjautuvaan interpolointimenetelmään. Analogisten interpolaattoreiden ohella muu olennainen toiminnallisuus toteutettiin FPGA:lle. Interpolaattorit käyttävät Miller-integraattoreita lineaarisuuden ja kertamittaustarkkuuden parantamiseksi. TDC:n nimellinen mittausalue on 84ms ja sillä saavutetaan 2ps:n kertamittaustarkkuus, kun mitattava aikaväli on lyhyempi kuin 2ms, minkä jälkeen mittaustarkkuus heikkenee referenssioskillaattorin vaihekohinan vaikutuksesta. Toinen pitkän kantaman TDC perustuu 0.35μm:n CMOS teknologialla totetutettuun integroituun piiriin. Aika-jännitemuunnoksen sijasta tämä TDC perustuu sykliseen/algoritmiseen interpolointitekniikkaan, jossa taajuusmoduloitua rengasoskillaattoria(SRO) käytetään kvantisointivirheen vahvistamiseksi. Interpolaattorit ovat yhdistetty 16-bittiseen referenssioskillaattorin laskuriin, jolloin TDC:n mittausalue on noin 327μs. Tämän TDC:n RMS kertamittaustarkkuus on 4.2ps, joka saavutetaan ilman epälineaarisuuden kompensointia. Samalle piirille on lisäksi toteutettu kalibrointitoiminnallisuus, jolla varmistetaan TDC:n hyvä mittaustarkkuus kaikissa olosuhteissa. Mittaustarkkuus poikkeaa maksimissaan vain ±2.5ps, kun lämpötila on välillä -30C-70C. Vaikka TDC on toteutettu kohtalaisen vanhalla CMOS teknologialla, interpolaattoreiden efektiivinen lineaarinen alue ja mittaustarkkuus edustavat alansa huippua

Abstract This thesis describes the development of a high precision time-to-digital converter (TDC) in which the conversion is based on a counter and three-stage stabilised delay line interpolation developed in this work. The biggest design challenges in the design of a TDC are related to the fact that the arrival moment of the hit signals (start and stop) is unknown and asynchronous with respect to the reference clock edges. Yet, the time interval measurement system must provide an immediate and unambiguous measurement result over the full dynamic range. It must be made sure that the readings from the counter and the interpolators are always consistent with very high probability. Therefore, the operation of the counter is controlled with a synchronising logic that is in turn controlled with the interpolation result. Another synchronising logic makes it possible to synchronise the timing signals with multiphase time-interleaved clock signals as if the synchronising was done with a GHz-level clock, and enables multi-stage interpolation. Multi-stage interpolation reduces the number of delay cells and registers needed. The delay line interpolators are stabilised with nested delay-locked loops, which leads to good stability and makes it possible to improve single-shot precision with a single look-up table containing the integral nonlinearities of the interpolators measured at the room temperature. A multi-channel prototype TDC was fabricated in a 0.6 μm digital CMOS process. The prototype reaches state-of-the-art rms single-shot precision of better than 20 ps and low power consumption of 50 mW as an integrated TDC.

Abstract The aim of this work was to improve the performance and usability of a digital time-to-digital converter (TDC) in CMOS technology. The characteristics of the TDC were improved especially for the needs of pulsed laser time-of-flight (TOF) distance measurement, where picosecond-level precision with a long µs-level measurement range is needed in order to approach mm-level measurement accuracy. Stability in the face of process, voltage and temperature variations, multiple measurement channels, alternative measurement modes, a high integration level, standard interfaces and simple usage were the main features for development. The measurement architecture is based on counter and timing signal interpolation on two levels. The counter counts the full reference clock cycles between the timing signals, while a new recycling delay line developed in this thesis interpolates within the reference clock cycle. This technique utilizes a short delay line several times per reference clock cycle, which minimizes the interpolation nonlinearity. The same structure also makes the use of a low, MHz-level reference frequency possible, and thus only a crystal is needed as an external oscillator component. The parallel load capacitor-scaled delay line structure acts as the second, sub-gate-delay interpolation level. The INL does not accumulate in elements connected in parallel, and the load capacitance differences enable high, ps-level resolution to be achieved. Four TDC circuits in 0.35 µm CMOS technology were designed and tested in the course of this work, of which the latest, a 7-channel TDC, is able to measure the time intervals between the start pulse and three separate stop pulses in one measurement and to resolve the pulse widths or rise times at the same time. In laser TOF distance measurement this functionality can be used when several echoes arrive at the receiver, and also to compensate for the detection threshold problem known as timing walk error. The TDC achieves 8.9 ps interpolation resolution within the cycle time of a 20 MHz reference clock using only 8 delay elements on the first interpolation level and 14 delay elements on the second. A measurement precision better than 9 ps was achieved without using result post-processing or look-up tables. This work shows that versatile, high performance TDCs can be created in standard CMOS technology
Tiivistelmä Väitöskirjatyön tavoitteena oli parantaa CMOS-aika-digitaalimuuntimien suorituskykyä ja käytettävyyttä. Muuntimen ominaisuuksia kehitettiin erityisesti laseretäisyysmittauksen tarpeita ajatellen, missä millimetritason mittaustarkkuus laajalla mittausaluella edellyttää aika-digitaalimuuntimelta pikosekuntitason tarkkuutta mikrosekuntien mittausalueella. Stabiilius prosessiparametri-, jännite- ja lämpötilavaihteluita vastaan, useat mittauskanavat, useat mittausmoodit, korkea integraatioaste, standardoidut liitäntäväylät ja helppo käytettävyys olivat erityisesti kehityksen kohteina. Suunniteltu mittausarkkitehtuuri koostuu laskurista ja kaksitasoisesta ajoitussignaali-interpolaattorista. Laskuri laskee kokonaiset referenssikellojaksot ajoitussignaalien välillä ja työssä kehitetty referenssiä kierrättävä viivelinjarakenne rekistereineen interpoloi ajoitussignaalien paikat referenssikellojaksojen sisältä. Referenssinkierrätystekniikka hyödyntää lyhyttä viivelinjaa useampaan kertaan kellojakson aikana, mikä minimoi epälineaarisuuden interpoloinnissa. Sama rakenne mahdollistaa myös MHz-tason referenssitaajuuden, jolloin matalataajuista kidettä voidaan käyttää referenssilähteenä. Toinen interpolointitaso koostuu rinnakkaisista kapasitanssiskaalatuista viive-elementeistä, mitkä mahdollistavat alle porttiviiveen mittausresoluution. Rinnakkaisessa rakenteessa elementtien epälineaarisuudet eivät summaudu, mikä mahdollistaa pikosekuntitason mittaustarkkuuden. Väitöskirjatyössä suunniteltiin ja toteutettiin neljä aikavälinmittauspiiriä käyttäen 0,35 µm CMOS-teknologiaa, joista viimeisin, 7-kanavainen muunnin kykenee mittaamaan aikavälin useampaan pulssiin yhdellä kertaa sekä voi selvittää samalla pulssien leveydet tai nousuajat. Laseretäisyysmittauksessa monikanavaisuutta voidaan käyttää kun useita kaikuja lähetetystä pulssista saapuu vastaanottimeen sekä kompensoimaan mittauksessa esiintyviä muita virhelähteitä. Käytettäessä 20 MHz:n kidettä referenssilähteenä muunnin saavuttaa alle 9 ps:n interpolointiresoluution ja tarkkuuden ilman epälineaarisuudenkorjaustaulukoita. Työ osoittaa, että edullisella CMOS-teknologialla voidaan toteuttaa monipuolinen ja erittäin suorituskykyinen aika-digitaalimuunnin

The measurement of engagement, or the interaction of a person with their environment, is an integral part of assessing the quality of an intervention program for young children diagnosed with autism spectrum disorder. Researchers and practitioners can and do measure engagement in many ways on the individual and group level. The purpose of this methodological study was to compare three commonly used recording systems: individual partial interval, group momentary time sampling, and group partial interval. These recording methods were compared across three classes of engagement: social, instructional, and non-instructional in a clinical setting with children with autism. Results indicate that group measurement systems were not sensitive to individual changes in engagement when child behaviors were variable. The results are discussed in the context of behavior analytic conceptual systems and the relative utility and future research directions for behavior analytic practice and research with young children in group settings.

A microcomputer based hardware, the Time Interval Board, was designed and the software interface control program was developed. The board measures time intervals between consecutive pulses from a discriminator output. The data is stored in on-board 16K x 16 memory. The microcomputer empties and processes the data when the on-board memory is filled. Data collection continues until the preset collection period is finished or a forced end is initiated. During this period, control is passed between the hardware and the microcomputer via the interface circuit. The designed hardware is IBM PC compatible.

The two most common methods to measure resting metabolic rate using indirect calorimetry are steady state or time interval. Steady state is commonly defined as the first five minutes in which oxygen consumption and carbon dioxide production vary by <10%. A time interval measurement generally lasts 20-60 minutes. Using steady state criteria is often harder to achieve, but many suggest it more accurately measures resting metabolic rate. Our objective was to determine if there were differences between steady state and time interval measurements in a healthy adult population. Seventy seven subjects were measured for 45 minutes. Inclusion criteria included healthy subjects ages 18-65, excluding pregnant and lactating women. Paired t-tests analyzed differences between measures, and Bland-Altman plots evaluated bias, precision, and accuracy. Of 77 subjects, 84% achieved steady state, and 95% achieved SS by minute 30. Most differences between steady state and time intervals were statistically but not practically significant. Bland-Altman plots showed steady state measurements were generally lower indicating that steady state is more indicative of resting metabolic rate. Minutes 6-25 were most precise, accurate and fairly unbiased compared to steady state. We recommend measuring a subject for 30 minutes and using steady state criteria of <10% variation of oxygen consumption and carbon dioxide production for five minutes if a subject is able to achieve it. However, if a subject cannot achieve steady state, we recommend averaging minutes 6-25.

Thesis (M.S. in physics)--Washington State University, December 2008.
Title from PDF title page (viewed on July 10, 2009). "Department of Physics and Astronomy." Includes bibliographical references (p. 64-68).

Abstract This thesis describes the development of high bandwidth (~1 GHz) TOF (time-of-flight) laser range finder techniques for industrial measurement applications in the measurement range of zero to a few dozen metres to diffusely reflecting targets. The main goal has been to improve single-shot precision to mm-level in order to shorten the measurement result acquisition time. A TOF laser range finder consists of a laser transmitter, one or two receivers and timing discriminators, and a time measuring unit. In order to improve single-shot precision the slew-rate of the measurement pulse should be increased, so the optical pulse of the laser transmitter should be narrower and more powerful and the bandwidth of the receiver should be higher without increasing the noise level too much. In the transmitter usually avalanche transistors are used for generating the short (3–10 ns) and powerful (20–100 A) current pulses for the semiconductor laser. Several avalanche transistor types were compared and the optimization of the switching circuit was studied. It was shown that as high as 130 A current pulses are achievable using commercially available surface mount avalanche transistors. The timing discriminator was noticed to give the minimum walk error, when high slew rate measurement pulses and a high bandwidth comparator were used. A walk error of less than +/- 1 mm in an input amplitude dynamic range higher than 1:10 can be achieved with a high bandwidth receiver channel. Adding an external offset voltage between the input nodes of the comparator additionally minimized the walk error. A prototype ~1 GHz laser range finder constructed in the thesis consists of a laser pulser and two integrated ASIC receiver channels with silicon APDs (avalanche photodiodes), crossover timing discriminators and Gilbert cell attenuators. The laser pulser utilizes an internal Q-switching mode of a commercially available SH-laser and produces optical pulses with a pulse peak power and FWHM (full-width-at-half-maximum) of 44 W and 74 ps, respectively. Using single-axis optics and 1 m long multimode fibres between the optics and receivers a total accuracy of +/-2 mm in the measurement range of 0.5–34.5 m was measured. The single-shot precision (σ-value) was 14 ps–34 ps (2–5 mm) in the measurement range. The single-shot precision agrees well with the simulations and is better with a factor of about 3-5 as compared to earlier published pulsed TOF laser radars in comparable measuring conditions.

Cardiovascular diseases are an increasing source of concern in modern societies due to their increasing prevalence and high impact on the lives of many people. Monitoring cardiovascular parameters in ambulatory scenarios is an emerging approach that can provide better medical access to patients while decreasing the costs associated to the treatment of these diseases. This work analyzes systems and methods to measure time intervals between the electrocardiogram (ECG), impedance plethysmogram (IPG), and the ballistocardiogram (BCG), which can be obtained at the limbs in ambulatory scenarios using simple and cost-effective systems, to assess cardiovascular intervals of interest, such as the pulse arrival time (PAT), pulse transit time (PTT), or the pre-ejection period (PEP). The first section of this thesis analyzes the impact of the signal acquisition system on the uncertainty in timing measurements in order to establish the design specifications for systems intended for that purpose. The minimal requirements found are not very demanding yet some common signal acquisition systems do not fulfill all of them while other capabilities typically found in signal acquisition systems could be downgraded without worsening the timing uncertainty. This section is also devoted to the design of systems intended for timing measurements in ambulatory scenarios according to the specifications previously established. The systems presented have evolved from the current state-of-the-art and are designed for adequate performance in timing measurements with a minimal number of active components. The second section is focused on the measurement of time intervals from the IPG measured from limb to limb, which is a signal that until now has only been used to monitor heart rate. A model to estimate the contributions to the time events in the measured waveform of the different body segments along the current path from geometrical properties of the large arteries is proposed, and the simulation under blood pressure changes suggests that the signal is sensitive to changes in proximal sites of the current path rather than in distal sites. Experimental results show that the PAT to the hand-to-hand IPG, which is obtained from a novel four-electrode handheld system, is correlated to changes in the PEP whereas the PAT to the foot-to-foot IPG shows good performance in assessing changes in the femoral PAT. Therefore, limb-to-limb IPG measurements significantly increase the number of time intervals of interest that can be measured at the limbs since the signals deliver information from proximal sites complementary to that of other measurements typically performed at distal sites. The next section is devoted to the measurement of time intervals that involve different waves of the BCG obtained in a standing platform and whose origin is still under discussion. From the relative timing of other physiological signals, it is hypothesized that the IJ interval of the BCG is sensitive to variations in the PTT. Experimental results show that the BCG I wave is a better surrogate of the cardiac ejection time than the widely-used J wave, which is also supported by the good correlation found between the IJ interval and the aortic PTT. Finally, the novel time interval from the BCG I wave to the foot of the IPG measured between feet, which can be obtained from the same bathroom scale than the BCG, shows good performance in assessing the aortic PAT. The results presented reinforce the role of the BCG as a tool for ambulatory monitoring since the main time intervals targeted in this thesis can be obtained from the timing of its waves. Even though the methods described were tested in a small group of subjects, the results presented in this work show the feasibility and potential of several time interval measurements between the proposed signals that can be performed in ambulatory scenarios, provided the systems intended for that purpose fulfill some minimal design requirements.
Les malalties cardiovasculars són una tema de preocupació creixent en societats modernes, degut a l’augment de la seva prevalença i l'elevat impacte en les vides dels pacients que les sofreixen. La mesura i monitoratge de paràmetres cardiovasculars en entorns ambulatoris és una pràctica emergent que facilita l’accés als serveis mèdics i permet reduir dràsticament els costos associats al tractament d'aquestes malalties. En aquest treball s’analitzen sistemes i mètodes per la mesura d’intervals temporals entre l’electrocardiograma (ECG), el pletismograma d’impedància (IPG) i el balistocardiograma (BCG), que es poden obtenir de les extremitats i en entorns ambulatoris a partir de sistemes de baix cost, per tal d’avaluar intervals cardiovasculars d’interès com el pulse arrival time (PAT), pulse transit time (PTT) o el pre-ejection period (PEP). En la primera secció d'aquesta tesi s’analitza l’impacte del sistema d’adquisició del senyal en la incertesa de mesures temporals, per tal d’establir els requeriments mínims que s’han de complir en entorns ambulatoris. Tot i que els valors obtinguts de l’anàlisi no són especialment exigents, alguns no són assolits en diversos sistemes habitualment utilitzats mentre que altres solen estar sobredimensionats i es podrien degradar sense augmentar la incertesa en mesures temporals. Aquesta secció també inclou el disseny i proposta de sistemes per la mesura d’intervals en entorns ambulatoris d’acord amb les especificacions anteriorment establertes, a partir de l’estat de l’art i amb l’objectiu de garantir un correcte funcionament en entorns ambulatoris amb un nombre mínim d’elements actius per reduir el cost i el consum. La segona secció es centra en la mesura d’intervals temporals a partir de l’IPG mesurat entre extremitats, que fins al moment només s’ha fet servir per mesurar el ritme cardíac. Es proposa un model per estimar la contribució de cada segment arterial per on circula el corrent a la forma d’ona obtinguda a partir de la geometria i propietats físiques de les artèries, i les simulacions suggereixen que la senyal entre extremitats és més sensible a canvis en arteries proximals que en distals. Els resultats experimentals mostren que el PAT al hand-to-hand IPG, obtingut a partir d’un innovador sistema handheld de quatre elèctrodes, està fortament correlacionat amb els canvis de PEP, mentre que el PAT al foot-to-foot IPG està correlat amb els canvis en PAT femoral. Conseqüentment, l’ILG entre extremitats augmenta de manera significativa els intervals d’interès que es poden obtenir en extremitats degut a que proporciona informació complementària a les mesures que habitualment s’hi realitzen. La tercera secció està dedicada a la mesura d’intervals que inclouen les ones del BCG vertical obtingut en plataformes, de les que encara se’n discuteix l’origen. A partir de la posició temporal relativa respecte altres ones fisiològiques, s’hipostatitza que l’interval IJ del BCG es sensible a variacions del PTT. Els resultats experimentals mostren que la ona I del BCG és un millor indicador de l’ejecció cardíaca que el pic J, tot i que aquest és el més utilitzat habitualment, degut a la bona correlació entre l’interval IJ i el PTT aòrtic. Finalment, es presenta un mètode alternatiu per la mesura del PTT aòrtic a partir de l’interval entre el pic I del BCG i el peu del foot-to-foot IPG, que es pot obtenir de la mateixa plataforma que el BCG i incrementa la robustesa de la mesura. Els resultats presentats reforcen el paper del BCG com a en mesures en entorns ambulatoris, ja que els principals intervals objectiu d’aquesta tesi es poden obtenir a partir de les seves ones. Tot i que els mètodes descrits han estat provats en grups petits de subjectes saludables, els resultats mostren la viabilitat i el potencial de diversos intervals temporals entre les senyals proposades que poden ésser realitzats en entorns ambulatoris, sempre que els sistemes emprats compleixin els requisits mínims de disseny.

Using 12-month post treatment Timeline Followback drinking reports, data extrapolated from shorter time windows (e.g., 1 month, 6 months) were used to estimate total annual drinking. The objective was to determine whether data from a shorter time window would provide an estimate of annual drinking sufficiently consistent with the full year report such that it can be used in place of the full report. Data for this study were obtained from problem drinkers who voluntarily participated in a randomized controlled trial of a mail-based intervention. Complete follow-up data were obtained for 467 of the 825 participants who completed a 12-month Timeline Followback of their post intervention drinking. The results of this study suggest that 3 months is the necessary minimum time window to best represent annual posttreatment drinking with alcohol abusers. The major implication of this finding is that alcohol treatment outcome studies can use a shorter posttreatment time window, which is more time and resource efficient, over which to obtain follow-up data with little to no loss in the representativeness of that data.

Background. Maintainability of software products continues to be an area of im- portance and interest both for practice and research. The time used for maintenance usually exceeds 70% of the whole period of software development process. At present, there is a large number of metrics that have been suggested to indicate the main- tainability of a software product. However, there is a gap in validation of proposed source code metrics and the external quality of software maintainability. Objectives. In this thesis, we aim to catalog the proposed metrics for software maintainability. From this catalog we will validate a subset of commonly proposed maintainability indicators. Methods. Through a literature review with a systematic search and selection ap- proach, we collated maintainability metrics from secondary studies on software main- tainability. A subset of commonly metrics identified in the literature review were validated in a retrospective study. The retrospective study used a large open source software "Elastic Search" as a case. We collected internal source code metrics and a proxy for maintainability of the system for 911 bug fixes in 14 version (11 experi- mental samples, 3 are verification samples) of the product. Results. Following a systematic search and selection process, we identified 11 sec- ondary studies on software maintainability. From these studies we identified 290 source code metrics that are claimed to be indicators of the maintainability of a soft- ware product. We used mean time to repair (MTTR) as a proxy for maintainability of a product. Our analysis reveals that for the "elasticsearch" software, the values of the four indicators LOC, CC, WMC and RFC have the strongest correlation with MTTR. Conclusions. In this thesis, we validated a subset of commonly proposed source code metrics for predicting maintainability. The empirical validation using a popu- lar large-scale open source system reveals that some metrics have shown a stronger correlation with a proxy for maintainability in use. This study provides important empirical evidence towards a better understanding of source code attributes and maintainability in practice. However, a single case and a retrospective study are insufficient to establish a cause effect relation. Therefore, further replications of our study design with more diverse cases can increase the confidence in the predictive ability and thus the usefulness of the proposed metrics.

Les processus caractérisant la turbulence en Méditerranée Occidentale ont été identifiés et quantifiés à partir de données de microstructure. L'accent a été mis sur le Canal de Sicile, un hot-spot pour le mélange turbulent et une région clé pour les transformations de masses d'eaux. Il module le transport de chaleur et de sel entre les deux bassins, occidental et oriental, et on y retrouve une large gamme de régimes dynamiques. La turbulence y est produite par le fort cisaillement associé à l'écoulement des eaux Levantines intermédiaires (LIW) fortement contraint par la bathymétrie et par le déferlement des ondes internes de marée. Un fort contraste entre les deux passages profonds dans le canal a ainsi été observé. La variabilité de l'efficacité du mélange a été caractérisée en fonction des régimes dynamiques rencontrés et une paramétrisation fine échelle de la dissipation d'énergie cinétique turbulente a été validée pour des régimes d'intensité turbulente faible à modérée. Les flux diffusifs turbulents verticaux calculés à partir de mesures in-situ ont permis d'estimer les changements des propriétés des masses d'eaux dans le canal. L'analyse a ensuite été étendue à tous les profils récoltés dans le bassin occidental où le rôle relatif de la double diffusion et de la turbulence mécanique sur les flux de chaleur, salinité, flottabilité et l'érosion de la LIW, a été discuté
The processes characterising turbulence in the Western Mediterranean Sea were identified and quantified using microstructure measurements. The focus was on the Sicily Channel, a hotspot for turbulent mixing and a key region for water mass transformations. It modulates the heat and salt transport from the Eastern to the Western Mediterranean Basins and exhibits a large range of dynamical regimes. Turbulence is driven by the strong shear associated to the flow of Levantine Intermediate Waters (LIW) which is constricted by the bathymetry, and by internal wave breaking of tidal origin. A strong contrast was observed between the two deep passages in the channel. The mixing efficiency variability was investigated in the context of mechanically driven turbulence over a wide spectrum of turbulence intensities. A finescale parameterisation for the turbulent kinetic energy dissipation rate was validated for weak to moderate turbulence intensity. The vertical turbulent diffusive fluxes computed from the measurements allowed an assessment of the water mass property changes incurred in the channel. The analysis was extended to all the stations sampled in the Western Mediterranean, where the relative impact of double diffusion and mechanical turbulence on heat, salt and buoyancy fluxes, as well as on the LIW, was investigated

Today, the main research field for the automotive industry is to find solutions for active safety. In order to perceive the surrounding environment, tracking nearby traffic objects plays an important role. Validation of the tracking performance is often done in staged traffic scenarios, where additional sensors, mounted on the vehicles, are used to obtain their true positions and velocities. The difficulty of evaluating the tracking performance complicates its development. An alternative approach studied in this thesis, is to record sequences and use non-causal algorithms, such as smoothing, instead of filtering to estimate the true target states. With this method, validation data for online, causal, target tracking algorithms can be obtained for all traffic scenarios without the need of extra sensors. We investigate how non-causal algorithms affects the target tracking performance using multiple sensors and dynamic models of different complexity. This is done to evaluate real-time methods against estimates obtained from non-causal filtering. Two different measurement units, a monocular camera and a LIDAR sensor, and two dynamic models are evaluated and compared using both causal and non-causal methods. The system is tested in two single object scenarios where ground truth is available and in three multi object scenarios without ground truth. Results from the two single object scenarios shows that tracking using only a monocular camera performs poorly since it is unable to measure the distance to objects. Here, a complementary LIDAR sensor improves the tracking performance significantly. The dynamic models are shown to have a small impact on the tracking performance, while the non-causal application gives a distinct improvement when tracking objects at large distances. Since the sequence can be reversed, the non-causal estimates are propagated from more certain states when the target is closer to the ego vehicle. For multiple object tracking, we find that correct associations between measurements and tracks are crucial for improving the tracking performance with non-causal algorithms.

Suen and Ary's (1986a) statistical model to specify time sampling intervals that should produce accurate estimates of response duration and frequency was tested. Intervals with low probability of error (appropriate) were compared to those with high probability of error (inappropriate), as determined by the Suen and Ary method. Discrepancy (from real-time data) indices were calculated for partial-interval, whole-interval, and momentary time-sampling methods using data from three social behaviors of two preschool children in 30 min observation sessions. In general, for both duration and frequency measures (for both children), all three time sampling methods produced statistically reliable error in comparison to real-time recording, However, reliably greater error was found with inappropriate than with appropriate intervals, in accord with Suen and Ary's model.

碩士
國立中央大學
土木工程研究所
98
It is an important and essential work to measure the deformation of the structure on health diagnosis. The far distance and noncontact optical measuring methods are convenient and popular because of structure fast diagnosis, but with some difficulty. This research developed a new type of noncontact structure displacement measurement system. The fundamental theorem of it is to transform the time interval variation of signals from ptical sensing instrument to a corresponding displacement variation. The key work of it is solving the triangle geometric relationship to formulate the relation between time interval and displacement. The laser displacement measurement system developed in this research has fast data processing algorithm so it can be more efficient compared with traditional measurement systems. Laboratory and field test results demonstrate that the remote laser displacement measurement system is quite accurate and efficient for structure condition evaluation.

碩士
輔仁大學
電子工程學系
94
Low power consumption is an important factor in designing PC systems. Dynamic power management (DPM) can be an effective approach to reduce power consumption without significantly degrading performance. When a system shuts down or wakes up, it requires extra power consumption. In this paper, we focus on the transition penalty of the power consumption of typical PCs. We built a dynamic power transition model for the transition penalty. According to our model, the estimation of the transition penalty of a PC system can result in more efficient DPM policies.

碩士
高雄醫學大學
醫學研究所碩士班
93
Introduction: In patients with hypertension, increases in arterial stiffness have been associated with a higher risk of coronary and cerebrovascular diseases. Arterial stiffness can be assessed noninvasively by measurement of pulse wave velocity (PWV). Practical problems in the measurement of PWV arise when the points of measurement (eg, carotid and femoral artery) are not in the same line of flow travel and the actual arterial distance between recording sites on the surface of the body was not exact. We developed a simple and novel index as QPV interval (msec) that was the time interval between the onset of QRS complex from a surface electrocardiogram and the point of peak flow velocity of left brachial artery (BA) determined by ultrasound. We proposed that this QPV interval can be served as an index marker of arterial stiffness. Methods: Sixty-six patients (mean age 49.3±10.5) with untreated essential hypertension were enrolled. Brachial-ankle PWV (baPWV) was determined by VP 1000 automated ABI/PWV analyzer and BA ultrasonography was prerformed simultanelusly to measure the QPV interval. The mean QPV interval was obtained by measuring the time interval at two consecutive pulsatile velocity waveform. Flow- and nitroglycerin-mediated vasodilation of BA were also determined. Results: The mean QPV interval was 196.1±18.9 msec (range 155-245 msec) and mean baPWV was 1785.7±293.3 cm/sec (range 1054-2514 cm/sec). The mean baPWV was significantly higher in patients with QPV interval≦195 msec than in patients with QPV interval＞195 msec (1955.7±255.1 vs. 1605.0±213.8 cm/sec, P < 0.001). Univariate linear regression demonstrated a significantly inverse correlation between QPV interval and baPWV (r =－0.671, P < 0.001). In a multivariate regression model that adjusted for age, sex, body mass index (BMI) and other potential baPWV determinants, the QPV interval was still inversely associated with baPWV (P < 0.001). No significant association could be demonstrated between baPWV and flow- or nitroglycerin-mediated vasodilation. Conclusions: In patients with untreated essential hypertension, QPV interval has significantly inverse correlation to baPWV, independent of BMI, age and other baPWV determinants. The QPV interval can be served as a simple and convenient parameter for assessing the severity of arterial stiffness.

碩士
元智大學
通訊工程學系
98
While measuring the SAR of a cellular phone, there are many factors(surrounding temperature, noise interference, tissue, the precision of the setup, and so on) that can influence the measuring results and cause erroneous variances. Therefore, The thesis apply the theory of confidence intervals to evaluate the reliability of the measuring results. Under a specific extent of confidence,we construct a set of rules concerning about the measurement.These will help shorten the product development period and reduce time to market, which will increase the competitiveness of the product.

碩士
國立中山大學
海下科技暨應用海洋物理研究所
99
Internal tide is generated in the interface of density stratification by some hydrodynamic disturbance. The major mechanisms are borotrophic tidal current oscillated at the edge of the continental shelf, submarine canyons, ridges or sills. The resulting disturbance generated has the same motion cycle of tidal period. There were internal tides reported in the Kaoping Submarine Canyon. The generation sites and mechanisms, however, are not clear. This study analysis four cruises of field observed data using ship mounted ADCP and CTD, and moored temperature strings and current meters. The results showed: (1) The phase of M2 tidal current increase toward the canyon head, with minimum value at the canyon mouth. This result implies that the internal tide was generated near the canyon mouth and propagated up canyon with the thermocline decreasing toward the shallower water. (2) The internal tide generated at the canyon mouth propagated, through some mechanisms, at the upper layer density interface about 150m instead of beaming near the bottom layer where the current and topography interact. (3) The vertical variations of tidal ellipse and phase based on bottom mounted ADCP support the results of ship mounted observations, the internal tidal energy propagates near the interface of 150m below the surface.

Eine verbesserte Methode zur Erfassung der Parameter interner Schwerewellen mit Hilfe von Winddaten eines Meteorradars wird vorgestellt. Die Analyse basiert auf der Einteilung des Messvolumens in Untervolumina und der Waveletanalyse der Windmessungen in diesen, mit anschließender Bestimmung der Phasenlage der spektralen Maxima. Auf diese Weise ist zum ersten Mal eine Statistik von Schwerewellenparametern aus Meteorradardaten unter Einschluss der horizontalen und vertikalen Wellenlängen und Ausbreitungsrichtungen erstellt worden. Es zeigte sich, dass sich der größte Teil der Schwerewellen sich oben ausbreitet. Hochfrequente Wellen mit Periodendauern unter 2 Stunden dominieren. Die Verteilung der erfassten Wellen innerhalb eines Tages zeigt eine geringe Struktur, mit Maxima am Morgen und Abend.