• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 10
  • 9
  • 3
  • 3
  • 1
  • 1
  • Tagged with
  • 30
  • 5
  • 5
  • 4
  • 4
  • 4
  • 3
  • 3
  • 3
  • 3
  • 3
  • 2
  • 2
  • 2
  • 2
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Měření náhradního obvodu piezoelektrického rezonátoru / Measurment of Equivalent Circuit of Piezoelectric Resonator

Vomočil, Vojtěch January 2010 (has links)
This theis deals with the general overview of the piezoelectric theory, focused both on the mathematical description and on the attributes of piezoelectric materials. It further focuses on the description of piezoelectric resonators with a more detailed explantation of their equivalent scheme and measurement methods of its single elements. The practical part of the thesis rests on the proposal of a measurement apparatus which will serve to measuring the equivalent circuit piezoelectric resonator elements. The realization of the apparatus and its functionality testing are described. In the experimental part of the thesis, the measured rates are processed and levels of the electric equivalent circuit elements of the used piesoelectric resonator for the basic and the two higher closest resonance frequency are set. The measured results are compiled into a standard measurement protocol. This thesis should place basics to the growing laboratory. It should also be a source of necessary theoretical and practical information for this lab.
22

Návrh na zlepšení řízení jakosti / Proposal for Improvement Quality Management in Company

Holubová, Pavla January 2010 (has links)
The thesis is target on the analysis of quality management in the company LABARA, s.r.o. There is described the methodology of quality in general and in context of customers satisfaction, which is subject of the theoretical part of this thesis. The practical part is target on suggestion of the evaluation system of customers satisfaction, on the interpretation of information and proposes for improving cutomers satisfaction.
23

Inventory Routing Investigations

Song, Jin-Hwa 08 July 2004 (has links)
The elimination of distribution inefficiencies, occurring due to the timing of customers' orders is an important reason for companies to introduce vendor managed inventory programs. By managing their customers' inventories, suppliers may be able to reduce demand variability and therefore distribution costs. We develop technology to measure the effectiveness of distribution strategies. We develop a methodology that allows the computation of tight lower bounds on the total mileage required to satisfy customer demand over a period of time. As a result, companies will be able to gain insight into the effectiveness of their distribution strategy. This technology can also be used to suggest desirable delivery patterns and to analyze tactical and strategic decisions. Secondly, we study the inventory routing problem with continuous moves (IRP-CM). The typical inventory routing problem deals with the repeated distribution of a single product, from a single facility, with an unlimited supply, to a set of customers that can all be reached with out-and-back trips. Unfortunately, this is not always the reality. We introduce the IRP-CM to study two important real-life complexities: limited product availabilities at facilities and customers that cannot be served using out-and-back tours. We need to design delivery tours spanning several days, covering huge geographic areas, and involving product pickups at different facilities. We develop a heuristic and an optimization algorithm to construct distribution plans. The heuristic is an innovative randomized greedy algorithm, which includes linear programming based postprocessing technology. To solve the IRP-CM to optimality, we give a time-discretized integer programming model and develop a branch-and-cut algorithm. As instances of time-discretized models tend to be large we discuss several possibilities for reducing the problem size. We introduce a set of valid inequalities, called delivery cover inequalities, in order to tighten the bounds given by the LP relaxation of the time-discretized model. We also introduce branching schemes exploiting the underlying structure of the IRP-CM. An extensive computational study demonstrates the effectiveness of the optimization algorithm. Finally, we present an integrated approach using heuristics and optimization algorithms providing effective and efficient technology for solving inventory problems with continuous moves.
24

Innovative numerical protection relay design on the basis of sampled measured values for smartgrids / Conception de relais de protection numérique innovants à base d'échantillons horodatés pour les smartgrids

Ghafari, Christophe 16 December 2016 (has links)
Avec le paradigme du réseau intelligent, les ingénieurs de protection ont maintenant à leur disposition une large gamme de nouvelles technologies de communication. Parmi elles, la norme CEI 61850-9-2 a introduit le concept de bus de procédé qui permet l'envoi de valeurs échantillonnées horodatées à un temps absolu depuis les transformateurs de mesure du terrain jusqu’aux relais de protection numériques. Ces derniers peuvent intégrer la fonction d'unité de mesure de phaseur qui peut être utilisé pour échanger des synchrophaseurs entre les fonctions de protection et pour une nouvelle protection anti-îlotage. Les relais de fréquence et de dérivée de fréquence sont, de nos jours, les méthodes anti-îlotage les plus couramment employées, mais leurs performances ne sont pas satisfaisantes. Dans ce contexte, une nouvelle génération de techniques de traitement du signal pour les relais de protection ayant des échantillons horodatées comme signal d'entrée et intégrant la mesure de synchrophaseurs est nécessaire. Cette thèse étudie d'abord l'impact des valeurs échantillonnées sur le traitement du signal. Trois solutions sont ensuite proposées pour calculer les phaseurs, les fréquences et les dérivées de fréquence dans diverses conditions statiques et dynamiques, puis testées par simulation. Enfin, un algorithme de mesure de synchrophaseurs incorporé dans le traitement de signal initial est proposé. Cet algorithme a été testé selon la dernière version de la norme d'unité de mesure de phaseur et les résultats obtenus sont conformes aux exigences de mesure. / With the Smart Grid paradigm, protection engineers now have available to them a large range of new communication technologies. Among them, IEC Standard 61850-9-2 has introduced the process bus concept which permits sending of absolute time-stamped digitized analogue values from the instrument transformers of the field to numerical relays. The latter can incorporate the phasor measurement unit function which can be used for exchanging synchrophasors between protection functions and for new anti-islanding protection. Frequency and rate-of-change-of-frequency relays are, nowadays, the most commonly employed anti-islanding methods but their performance is not satisfactory. In this context, a new generation of signal processing techniques for protection relays having time-stamped digitized analogue values as input signal with synchrophasors measurement capability is required. This thesis first studies the impact of sampled measured values on the signal processing. Three solutions are then proposed to compute phasor, frequency and rate-of-change-of-frequency estimates under various static and dynamic conditions, and tested via simulation. Finally, a synchronized phasor measurement algorithm incorporated into the initial signal processing is proposed. This algorithm has been tested following the latest version of the phasor measurement unit standard and the results obtained comply with the measurement requirements.
25

Akustické mikroklima nevýrobních objektů / Acoustic microclimate non-manufacturing buildings

Jelínek, Ondřej January 2013 (has links)
This master´s thesis focuses on effect of acoustic microclimate in non-production buildings to human. Within elaboration this topic was made measurment acoustic power level and created protocols by valid technical standards and law. I dedicate to damping noise and aerodynamic noise in airconditioning in part topic analysis. The part aplication on real object deal with assessment current status and draft measure for improve acoustic ratio in laboratories in center of research located in Brno. That includes describe of air-cndition unit and development two variants and their rating.
26

Systém pro sledování trajektorie objektů pohybujících se v prostoru / System for Trajectory Tracking of Objects Moving in Space

Jakubíček, Patrik January 2016 (has links)
This thesis deals with a system for tracking the trajectory of the moving object. Further, also for obtaining additional motion data and other information. Thesis focuses on flying objects. There are described all system components and way of their communication. Next, the progress of the expansion unit for measuring by the BeagleBone Black platform. Also there is described testing that took place during aerobatic gliders races, including the demonstrations of recording data and their processing.
27

Power GaN FET Testing

Faruque, Shams Omar January 2014 (has links)
No description available.
28

Development and deployment of an Inner Detector Minimum Bias Trigger and analysis of minimum bias data of the ATLAS experiment at the Large Hadron Collider

Kwee, Regina 19 July 2012 (has links)
Weiche inelastische QCD Prozesse dominieren am LHC. Über 20 solcher Kollisionen werden innerhalb einer Strahlkreuzung bei ATLAS stattfinden, sobald der LHC die nominelle Luminosität von L = 1034 cm−2 s−1 und die Schwerpunktsenergie von p s = 14 TeV erreicht. Diese inelastischen Wechselwirkungen sind durch einen geringen Impulsübertrag gekennzeichnet, welche theoretisch lediglich durch phänomenologische Modelle angenähernd beschrieben werden können. Zu Beginn des Strahlbetriebs des LHC’s 2009 war die Luminosität relativ niedrig mit L = 1027 bis 1031 cm−2 s−1, was ein sehr gutes Szenario bot, um einzelne Proton-Proton Kollisionen zu selektieren und deren allgemeine Eigenschaften experimentell zu untersuchen. Zunächst wurde ein Minimum-Bias Trigger entwickelt, um Daten mit ATLAS aufzunehmen. Dieser Trigger, mbSpTrk, verarbeitet Signale der Silizium-Spurdetektoren und verwirft effizient Ereignisse ohne eine Proton-Wechselwirkung, wobei zugleich eine mögliche Verschiebung zu bestimmten Ereignistypen hin minimier wird. Um einen flexiblen Einsatz des Triggers zu gewährleisten, wurde er mit einer Sequenz ausgestattet, welche effizient Machinenuntergrund unterdrückt. Im zweiten Teil der Arbeit wurden geladenen Teilchenmultiplizitäten im zentralen Bereich in zwei kinematisch definierten Phasenräumen gemessen. Mindestens ein geladenes Teilchen mit einer Pseudorapidität kleiner als 0.8 und einem Transversalimpuls von pT > 0.5 bzw. 1 GeV musste vorhanden sein. Vier typische Minimum-Bias Verteilungen wurden bei zwei Schwerpunktsenergien von p s = 0.9 und 7 TeV gemessen. Die Ergebnisse sind derart präsentiert, dass sie nur minimal von Monte Carlo Modellen abhängen. Die vorgestellten Messungen stellen zudem den Beitrag der ATLAS Kollaboration dar für die erste, LHC-weit durchgeführte Analyse, der auch die CMS und ALICE Kollaborationen zustimmten. Ein Vergleich konnte mit den Pseudorapiditätsverteilungen angestellt werden. / Soft inelastic QCD processes are the dominant proton-proton interaction type at the LHC. More than 20 of such collisions pile up within a single bunch-crossing at ATLAS, when the LHC is operated at design luminosity of L = 1034 cm−2 s−1 colliding proton bunches with an energy of p s = 14 TeV. Inelastic interactions are characterised by a small transverse momemtum transfer and can only be approximated by phenomenological models that need experimental data as input. The initial phase of LHC beam operation in 2009, with luminosites ranging from L = 1027 to 1031 cm−2 s−1, offered an ideal period to select single proton-proton interactions and study general aspects of their properties. As first part of this thesis, a Minimum Bias trigger was developed and used for data-taking in ATLAS. This trigger, mbSpTrk, processes signals of the silicon tracking detectors of ATLAS and was designed to fulfill efficiently reject empty events, while possible biases in the selection of proton-proton collisions is reduced to a minimum. The trigger is flexible enough to cope also with changing background conditions allowing to retain low-pT events while machine background is highly suppressed. As second part, measurements of inelastic charged particles were performed in two phase-space regions. Centrally produced charged particles were considered with a pseudorapidity smaller than 0.8 and a transverse momentum of pT > 0.5 or 1 GeV. Four characteristic distributions were measured at two centre-of-mass energies of p s = 0.9 and 7 TeV. The results are presented with minimal model dependency to compare them to predictions of different Monte Carlo models for soft particle production. This analysis represents also the ATLAS contribution for the first common LHC analysis to which the ATLAS, CMS and ALICE collaborations agreed. The pseudorapidity distributions for both energies and phase-space regions are compared to the respective results of ALICE and CMS.
29

Voltametrijske metode zasnovane na ugljeničnim elektrodama modifikovane kompozitima na bazi višezidnih ugljeničnih nanocevi i čestica bizmuta ili antimona za određivanje odabranih ciljnih analita / Voltammetric methods based on carbon electrodes modified with multi walled carbon nanotubes and bismuth and antimony particles based composites for determination of selected target analytes

Petrović Sandra 12 September 2019 (has links)
<p>Cilj ove doktorske disertacija&nbsp; bio je razvoj&nbsp; novih, osetljivih, selektivnih i ekonomski<br />isplativih&nbsp; voltametrijskih&nbsp; radnih&nbsp; elektroda&nbsp; za&nbsp; praćenje&nbsp; odabranih&nbsp; analita&nbsp; kako&nbsp; u<br />laboratorijskim tako i pri terenskim uslovima.&nbsp; Ispitivana je&nbsp; mogućnost primene&nbsp; ovih&nbsp; radnih&nbsp; elektroda&nbsp; primenom&nbsp; voltametrijskih&nbsp; metoda&nbsp; kako&nbsp; u&nbsp; model&nbsp; rastvorima&nbsp; tako&nbsp; i&nbsp; u&nbsp; pojedinim realnim sistemima. SW-ASV&nbsp; zasnovana&nbsp; na&nbsp; elektrodama&nbsp; od&nbsp; staklastog&nbsp; ugljenika&nbsp; povr&scaron;inski modifikovanim&nbsp; Bi-MWCNT&nbsp; i&nbsp; BiOCl-MWCNT&nbsp; je&nbsp; primenjena&nbsp; za&nbsp; određivanje&nbsp; jona&nbsp; Pb(II)&nbsp; i Cd(II)&nbsp; pri&nbsp; optimizovanim&nbsp; uslovima&nbsp; merenja.&nbsp; Određivanje&nbsp; ciljnih&nbsp; jona&nbsp; vr&scaron;eno&nbsp; je&nbsp; pri&nbsp; radnom potencijalu&nbsp; od&nbsp; -1,2&nbsp; V&nbsp; (izmeren&nbsp; u&nbsp; odnosu&nbsp; na&nbsp; zasićenu&nbsp; kalomelovu&nbsp; elektrodu)&nbsp; i&nbsp; vremenu<br />elektrodepozicije jona&nbsp; od 120 s. Sva merenja su izvr&scaron;ena u rastvoru acetatnog pufera čija je pH-vrednost iznosila&nbsp; 4,0. Primenjeni koncentracioni opseg ciljnih analita iznosio je&nbsp; od 5 do 50&nbsp; &mu;g&nbsp; dm <sup>-3</sup> .&nbsp; Primenom&nbsp; ovog&nbsp; tipa&nbsp; elektrode&nbsp; dobijene&nbsp; su&nbsp; vrednosti&nbsp; granice&nbsp; detekcije&nbsp; za&nbsp; jone Pb(II) i Cd(II) 0,57&nbsp; &mu;g dm <sup>-3 </sup>i 1,2 &mu;g dm<sup>-3</sup> , redom. Dobijena RSD iznosila je manje od 10% za oba&nbsp; jona.&nbsp; Ova&nbsp; metoda&nbsp; je&nbsp; primenjena&nbsp; i&nbsp; za&nbsp; određivanje&nbsp; ciljnih&nbsp; jona&nbsp; u&nbsp; realnom&nbsp; uzorku&nbsp; porne vode&nbsp; sedimenta&nbsp; a&nbsp; rezultati&nbsp; dobijeni&nbsp; optimizovanom&nbsp; voltametrijskom&nbsp; metodom&nbsp; su&nbsp; u&nbsp; dobroj saglasnosti sa rezultatima koji su dobijeni primenom komparativne GFAAS metode. Bizmut oksihlorid-vi&scaron;ezidne ugljenične nanocevi kompozitni materijal je primenjen za povr&scaron;insko&nbsp; modifikovanje&nbsp; elektrode&nbsp; od&nbsp; staklastog&nbsp; ugljenika&nbsp; za&nbsp; brzo&nbsp; i&nbsp; jednostavno voltametrijsko&nbsp; određivanje&nbsp; tragova&nbsp; Zn(II)-jona&nbsp; primenom&nbsp; SW-ASV&nbsp; metode.&nbsp; BiOClMWCNT/GCE je pokazala linearan analitički odgovor u&nbsp; osegu koncentracija od&nbsp; 2,50 do&nbsp; 80,0 &mu;g&nbsp; dm <sup>-3 </sup>sa dobijenom vredno&scaron;ću GD 0,75 &mu;g&nbsp; dm<sup>-3 </sup>pri akumulacionom vremenu od&nbsp; 120 s&nbsp; i potencijalu&nbsp; elektrodepozicije&nbsp; -1,40&nbsp; V&nbsp; u&nbsp; odnosu&nbsp; na&nbsp; ZKE.&nbsp; Merenja&nbsp; su&nbsp; vr&scaron;ena&nbsp; u&nbsp; acetatnom puferu pH 4,5. Dobijena RSD iznosila je 4,8 %. Upoređene su performanse novodizajnirane BiOCl-MWCNT/GCE elektrode&nbsp; i&nbsp; tradicionalne elektrode na bazi bizmut filma (BiF/GCE), MWCNT/GCE,&nbsp; BiF-MWCNT/GCE&nbsp; i&nbsp; nemodifikovane&nbsp; GC&nbsp; elektrode.&nbsp; Novodizajnirana elektroda je primenjena za&nbsp; detekciju&nbsp; i određivanje&nbsp; Zn(II)-jona&nbsp; u realnim&nbsp; uzorcima kao &scaron;to su<br />dijetetski&nbsp; suplement&nbsp; i&nbsp; pekarski&nbsp; kvasac.&nbsp; Dobijeni&nbsp; rezultati&nbsp; su&nbsp; uporedivi&nbsp; sa&nbsp; deklarisanom vredno&scaron;ću&nbsp; u&nbsp; slučaju&nbsp; dijetetskog&nbsp; suplementa&nbsp; a&nbsp; u&nbsp; slučaju&nbsp; pekarskog&nbsp; kvasca&nbsp; sa&nbsp; rezultatima dobijenih komparativnom FAAS .<br />Elektroda od ugljenične paste je povr&scaron;inski modifikovana pripremljenim kompozitom<br />koji je&nbsp; izgrađen od vi&scaron;ezidnih ugljeničnih nanocevi i čestica&nbsp; Sb<sub>2</sub>O<sub>3.</sub>&nbsp; Kompozitni&nbsp; materijal&nbsp; je okarakterisan&nbsp; primenom&nbsp; TEM,&nbsp; EDS&nbsp; i&nbsp; XRD&nbsp; mernih&nbsp; tehnika.&nbsp; Sb<sub>2</sub>O<sub>3</sub>-MWCNT/CPE&nbsp; je okarakterisana primenom ciklične voltametrije a merenja su vr&scaron;ena u rastvoru hlorovodonične kiseline&nbsp; (pH&nbsp; 2,0).&nbsp; Primenom&nbsp; SW-ASV&nbsp; metode&nbsp; ova&nbsp; radna&nbsp; elektroda&nbsp; je&nbsp; upotrebljena&nbsp; za određivanje&nbsp; jona Pb(II) i Cd(II)&nbsp; u&nbsp; koncentracionom opsegu 2,0-40,0&nbsp; &mu;g&nbsp; dm&nbsp; <sup>-3 </sup>za&nbsp; Pb(II)-jon&nbsp; i 2,0-40,0&nbsp; &mu;g&nbsp; dm <sup>-3</sup> za&nbsp; Cd(II)-jon&nbsp; pri&nbsp; čemu&nbsp; su&nbsp; dobijene&nbsp; dobre&nbsp; linearne&nbsp; zavisnosti&nbsp; za&nbsp; oba&nbsp; ciljna jona.&nbsp; Optimalna&nbsp; procedura&nbsp; uključuje&nbsp; primenu&nbsp; Sb2O3-MWCNT/CPE&nbsp; u&nbsp; 0,01&nbsp; mol dm <sup>-3</sup><br />hlorovodoničnoj kiselini uz vreme elektrodepozicije jona iz rastvora od 120&nbsp; s&nbsp; na&nbsp; potencijaluod&nbsp; -1,2&nbsp; V,&nbsp; pri&nbsp; čemu&nbsp; su&nbsp; dobijene&nbsp; vrednosti&nbsp; za&nbsp; GD&nbsp; 1,1&nbsp; &mu;g&nbsp; dm <sup>-3</sup> Cd(II)&nbsp; i&nbsp; 1,6&nbsp; &mu;g&nbsp; dm <sup>-3</sup> Pb(II). Optimizovana&nbsp; metoda&nbsp; zasnovana&nbsp; na&nbsp; ovom&nbsp; tipu&nbsp; voltametrijskog&nbsp; senzora&nbsp; je&nbsp; uspe&scaron;no primenjena&nbsp; za&nbsp; određivanje&nbsp; jona&nbsp; Cd(II)&nbsp; u&nbsp; obogaćenom&nbsp; uzorku&nbsp; česmenske&nbsp; vode,&nbsp; gde&nbsp; su&nbsp; se dobijene vrednosti u&nbsp; saglasnosti sa očekivanom. Elektroda od ugljenične paste povr&scaron;inski je&nbsp; modifikovana primenom&nbsp; Sb<sub>2</sub>O<sub>3</sub>-MWCNT nanokompozitnog&nbsp; materijala&nbsp; i&nbsp; primenjena&nbsp; za&nbsp; direktno&nbsp; voltametrijsko&nbsp; određivanje imidakloprida&nbsp; u&nbsp; model&nbsp; rastvorima.&nbsp; U&nbsp; cilju&nbsp; postizanja&nbsp; &scaron;to&nbsp; boljih&nbsp; analitičkih&nbsp; performansi optimizovani su eksperimentalni uslovi merenja kao &scaron;to su pH-vrednost rastvora pomoćnog elektrolita&nbsp; i&nbsp; kondicioniranje&nbsp; povr&scaron;ine&nbsp; voltametrijskog&nbsp; senzora.&nbsp; Kao&nbsp; optimalna&nbsp; pH-vrednost pomoćnog elektolita (Britton-Robinsonovog pufera) odabrana je pH 7,0, a ponavljanje ciklusa cikliranja najmanje 4 puta povoljno utiče na stabilnost&nbsp; voltametrijskih signala. Optimizovana metoda primenjena je za SW direktno katodno određivanje imidakloprida u koncentracionom intervalu od 1,41 do 32,77 &mu;g cm <sup>-3</sup> uz dobijeni korelacioni faktor od 0,9995. Na osnovu dobijenih rezultata može se zaključiti da su razvijene analitičke metode pre svega&nbsp; osetljive,&nbsp; selektivne,&nbsp; reproduktivne&nbsp; i&nbsp;&nbsp; jednostavne&nbsp; &scaron;to&nbsp; omogućava&nbsp; njihovu&nbsp; primenu&nbsp; za veliki broj uzoraka.&nbsp; Merenjima u model i realnim rastvorima dokazana je mogućnost njihove primene&nbsp; u&nbsp;&nbsp; komplikovanim&nbsp; matriksima,&nbsp; pri&nbsp; različitim&nbsp; pH&nbsp; vredostima&nbsp; pri&nbsp; čemu&nbsp; su&nbsp; dobijeni<br />rezultati koji su u saglasnosti sa rezultatima primenjenih komparativnih metoda. Naravno, za dobijanje&nbsp; reprezentativnih&nbsp; rezultata&nbsp; neohodno&nbsp; je&nbsp; izvr&scaron;iti&nbsp; optimizaciju&nbsp; uslova&nbsp; merenja&nbsp; &scaron;to podrazumeva sam odabir supstrat-elektrode, odabir povr&scaron;inskog modifikatora i optimizaciju eksperimentalnih uslova merenja.</p> / <p>The&nbsp; aim of this&nbsp; Ph.D. thesis&nbsp; was the development of new, sensitive, selective and economically&nbsp; viable&nbsp; voltametric&nbsp; working&nbsp; electrode&nbsp; for&nbsp; continuous&nbsp; monitoring&nbsp; of&nbsp; different target&nbsp; analytes.&nbsp; The&nbsp; use&nbsp; of&nbsp; these&nbsp; advantaged&nbsp; working&nbsp; electrodes&nbsp; was&nbsp; investigated&nbsp; using voltametric methods both in model solutions and in certain real systems.SW-ASV&nbsp; based on glassy carbon&nbsp; electrode surface modified with&nbsp; Bi- MWCNT and BiOCl-MWCNT&nbsp; were&nbsp; applied&nbsp; for&nbsp; determination&nbsp; of&nbsp; Pb(II)&nbsp; and&nbsp; Cd(II)&nbsp; ions.&nbsp; Voltametric determination&nbsp; of&nbsp; Pb(II)&nbsp; and&nbsp; Cd(II)&nbsp; ions&nbsp; was&nbsp; performed&nbsp; at&nbsp; working&nbsp; potential&nbsp; of&nbsp; -1.2&nbsp; V (measured against the saturated calomel electrode) and time of electrodeposition of 120 s. All measurements were performed in acetate buffer solution pH 4.0. Concentration range of targetanalites were&nbsp; 5-50 &mu;g&nbsp; dm -3 . Using this type of electrode,&nbsp; obtained&nbsp; detection limits for&nbsp; Pb(II) and Cd(II) ions&nbsp; were&nbsp; 0.57&nbsp; &mu;g&nbsp; dm -3 and 1.2&nbsp; &mu;g&nbsp; dm -3 , respectively, with RSD lower than 10%.This&nbsp; method&nbsp; was&nbsp; applied&nbsp; for&nbsp; target&nbsp; ions&nbsp; determination&nbsp; in&nbsp; sediment&nbsp; pore&nbsp; water&nbsp; sample,&nbsp; and obtained results are comparable with those who are obtained using GFAAS method. Bismuth oxychloride-multiwalled carbon nanotubes composite material was applied for&nbsp; surface&nbsp; modification&nbsp; of&nbsp; the&nbsp; glass-carbon&nbsp; electrode&nbsp; for&nbsp; quick&nbsp; and&nbsp; simple&nbsp; voltametric determination&nbsp; of&nbsp; Zn(II)&nbsp; ions&nbsp; using&nbsp; the&nbsp; SW-ASV&nbsp; method.&nbsp; BiOCl-MWCNT/GCE&nbsp; showed&nbsp; a linear&nbsp; analytical&nbsp; response&nbsp; in&nbsp; a&nbsp;&nbsp; concentration&nbsp; from&nbsp; 2.50&nbsp; to&nbsp; 80.0&nbsp; &mu;g&nbsp; dm -3 with&nbsp; a&nbsp; value&nbsp; of detection limit 0.75 &mu;g dm -3 at a acumulation time of 120 s and an electrodeposition potential of&nbsp; -1.40 V vs. saturated&nbsp; calomel electrode.&nbsp; Measurements were carried out in acetate buffer pH 4.5. The obtained&nbsp; value of the RSD&nbsp; was&nbsp; 4.8%. The performance of the newly designed BiOCl-MWCNT/GCE&nbsp; electrode,&nbsp; traditional&nbsp; bismuth-based&nbsp; electrode&nbsp; (BiF/GCE), MWCNT/GCE,&nbsp; BiF-MWCNT/GCE&nbsp; and&nbsp; unmodified&nbsp; GC&nbsp; electrodes&nbsp; were&nbsp; compared.&nbsp; The applied electrode shows very good electroanalytic properties when determining this target ion. Obtained results are in good agreement with declared value in case of dietetic suplement, and in the brewer&rsquo;s yeast sample results were comparable with FAAS results. Carbon&nbsp; paste&nbsp; electrode&nbsp; surface&nbsp; modified&nbsp; with&nbsp; new&nbsp; composite&nbsp; material&nbsp; based&nbsp; on multiwalled carbon nanotubes and&nbsp; Sb2O3&nbsp; particles. The composite is characterized by TEM, EDS and&nbsp; XRD measurment. Sb2O3- MWCNT/CPE was characterized by cyclic voltammetry and measurements were carried out in a&nbsp; hydrochloric acid&nbsp; solution&nbsp; (pH 2.0). Using the SWASV&nbsp; method,&nbsp; this&nbsp; working&nbsp; electrode&nbsp; was&nbsp; used&nbsp; to&nbsp; determine&nbsp; Pb(II),&nbsp; Cd(II)&nbsp; ions&nbsp; in&nbsp; the concentration range&nbsp; from&nbsp; 2.0&nbsp; to 40.0&nbsp; &mu;g dm -3 for Pb(II) and 2.0-40.0&nbsp; &mu;g dm -3 for Cd(II) ions. Newly&nbsp; designed&nbsp; sensor&nbsp; showed&nbsp; good&nbsp; linear&nbsp; dependences&nbsp; for&nbsp; both&nbsp; target&nbsp; ions.&nbsp; The&nbsp; most optimal&nbsp; procedure&nbsp; involving&nbsp; application&nbsp; of&nbsp; Sb2O3-MWCNT/CPE&nbsp; in&nbsp;&nbsp; .01&nbsp; mol&nbsp; dm -3 hydrochloric&nbsp; acid,&nbsp; with&nbsp; electroposition&nbsp; time&nbsp; of&nbsp; target&nbsp; ions&nbsp; 120&nbsp; s&nbsp; at&nbsp; a&nbsp; electrodeposition potential&nbsp; of&nbsp; -1.2&nbsp; V.&nbsp; Obtained&nbsp;&nbsp; values&nbsp; of&nbsp;&nbsp;&nbsp; LOD&nbsp; 1,1&nbsp; &mu;g&nbsp; dm -3 for&nbsp; Cd(II)&nbsp; and&nbsp; for&nbsp; 1,6&nbsp; &mu;g&nbsp; dm -3 Pb(II)&nbsp; ions.&nbsp; An&nbsp; optimized&nbsp; method&nbsp; based&nbsp; on&nbsp; this&nbsp; type&nbsp; of&nbsp; voltametric&nbsp; sensor&nbsp; has&nbsp; been successfully&nbsp; applied&nbsp; for&nbsp; determination&nbsp; of&nbsp; Cd(II)&nbsp; ion&nbsp; in&nbsp; a&nbsp; spiked&nbsp; tap&nbsp; water&nbsp; sample.&nbsp; Results obtained during this measurment were in tune with expected results. CPE&nbsp; was&nbsp; surface&nbsp; modified&nbsp; using&nbsp; Sb2O3-MWCNT&nbsp; nanocomposite&nbsp; material&nbsp; and tested&nbsp; for&nbsp; direct&nbsp; voltametric&nbsp; determination&nbsp; of&nbsp; imidacloprid&nbsp; in&nbsp; model&nbsp; solutions.&nbsp; In&nbsp; order&nbsp; to achieve the best analytical performance, experimental conditions of measurement such as the pH value of the supporting electrolyte and conditioning of the voltametric sensor surface havebeen&nbsp; optimized.&nbsp; As&nbsp; an&nbsp; optimum&nbsp; pH&nbsp; value&nbsp; of&nbsp; the&nbsp; supporting&nbsp; electrolyte&nbsp; (Britton-Robinson buffer), a pH 7.0 was selected, and the repeating cycles of the cycling process at least 4 times favorably&nbsp; influenced&nbsp; the&nbsp; stability&nbsp; of&nbsp; the&nbsp; voltametric&nbsp; signals.&nbsp; The&nbsp; optimized&nbsp; method&nbsp; was applied for the SW direct cathodic determination&nbsp; of&nbsp; imidacloprid in the concentration range from 1.41 to 32.77 &mu;g cm -3&nbsp; with obtained correlation factor of 0.9995. Based on results it can be concluded that developed analytical methods are sensitive, selective, reproducibile and simple, which can enable their application for various number of samples. Measurements in the model and real solutions have demonstrated the possibility of their&nbsp; application&nbsp; in&nbsp; complicated&nbsp; matrices,&nbsp; at&nbsp; different&nbsp; pH,&nbsp; whereby&nbsp; obtained&nbsp; results&nbsp; are&nbsp; in accordance&nbsp; with&nbsp; the&nbsp; results&nbsp; of&nbsp; the&nbsp; applied&nbsp; comparative&nbsp; methods.&nbsp; For&nbsp; obtainig&nbsp; of representative&nbsp; results&nbsp; it&nbsp; is&nbsp; necessary&nbsp; to&nbsp; optimize&nbsp; conditions&nbsp; of&nbsp; measurment&nbsp; which&nbsp; include: selection of substrat electrode, surface modifier and optimization of experimental condition.</p>
30

Effects of skin color on the Accuracy of heart ratedetection of commercial wearable devices / Effekten av olika hudfärger på nogrannheten vidmätning av hjärtslag med olika kommersiella bärbaraenheter

Jaber, Hussein January 2023 (has links)
The ownership and demand for fitness trackers, smartwatches, and wrist-worn deviceshave been increasing globally. These devices offer various features such as measuringphysical activity, sleep monitoring, and health-related measurements like heart rate andheart rate variability using PhotoPlethysmoGraphy (PPG). However, research indicatesthat PPG measurements are less accurate on darker skin compared to lighter skin due to thehigher presence of melanin, a light-absorbing substance in dark skin.This thesis addresses the impact of melanin on the accuracy of heart rate measurements ondifferent skin colors using four commercial smartwatches, Apple Watch Series 5, FitbitCharge 2, Xiaomi Miband 3, and Sony mSafety. The study involves analyzing the accuracyof these smartwatches on individuals with varying skin colors while controlling forexternal factors. The collected data from the smartwatches are compared to a referencesensor that uses electrocardiography (ECG) measurements with electrodes placed aroundthe chest. Three different tests are conducted wearing the devices, with no movement,while walking, and with circular hand motions.The tests were conducted on twelve participants representing the 6 different skin typescategorized using the Fitzpatrick scale. With the presented results in this thesis, it wasconcluded that the 4 smartwatches' measurement accuracy does not seem to be dependenton specific skin types. Ranked in terms of Mean Absolute Error (MAE), the Apple Watchshowed the lowest value, followed by Xiaomi, Fitbit and the mSafety and that the accuracydid not depend on skin color. / Ägandet och efterfrågan av smartklockor har ökat globalt. Dessa enheter erbjuder olikafunktioner som mäter fysisk aktivitet, övervakning av sömn och hälsorelaterade mätningarsom puls och hjärtfrekvensvariabilitet med hjälp av PhotoPlethysmoGraphy (PPG).Forskning har dock visat att PPG-mätningar är mindre noggranna på mörkare hud jämförtmed ljusare hud på grund av den högre närvaron av substansen melanin, ettljusabsorberande ämne.Syftet med detta arbete är att undersöka påverkan av melanin på noggrannheten i pulsmätningar på olika hudfärger med hjälp av fyra kommersiella smartklockor: Apple WatchSeries 5, Fitbit Charge 2, Xiaomi Miband 3 och mSafety av Sony. Arbetet inkluderar enanalys av dessa smartklockors noggrannhet på personer med de olika hudfärger samtidigtsom externa faktorer som kan påverka noggrannheten kontrolleras. De insamlade data frånsmartklockorna jämförs med en referenssensor, Polar band, som använderelektrokardiografimätningar (ECG) med elektroder. Tre olika tester utförs med enheterna,utan rörelse, medan man går och med cirkulära handrörelser.Testerna utfördes på tolv deltagare som representerar olika hudtyper kategoriserade enligtFitzpatrick-skalan. Utifrån de presenterade resultaten i denna avhandling drogs slutsatsenatt de fyra smartklockornas mätnoggrannhet inte verkar vara beroende av specifikahudtyper. Rankade i termer av Mean Absolute Error (MAE) visade Apple Watch det lägstavärdet, följt av Xiaomi, Fitbit och mSafety.

Page generated in 0.0509 seconds