Search results for "frequency [modulation]"

Different methods to clean up ultra high frequency data

2008

Modeling, Design and Experimentation of Wearable RFID Sensor Tag

2010

Design of effective wearable tags for UHF RFID applications involving persons is still an open challenge due to the strong interaction of the antenna with the human body which is responsible of impedance detuning and efficiency degradation. A new tag geometry combining folded conductors and tuning slots is here discussed through numerical analysis and extensive experimentation also including the integration of a passive motion detector. The achieved designs, having size comparable with a credit card, may be applied to any part of the body. The measured performance indicates a possible application of these body-worn tags for the continuous tracking of human movements in a conventional room.

A new method to "clean up" ultra high-frequency data

2007

In the applied econometrics, the availability of ultra high-frequency databases is having an important impact on the research market microstructure theory. The ultra high-frequency databases contain detailed reports of all the financial market activity information which is available. However, ultra high-frequency databases cannot be directly used. On one hand recording mistakes can be present, on the other hand missing information has to be inferred from the available data. In this paper, we propose a simple method in order to clean up the ultra high-frequency data from possible errors and we examine the method efficacy when we analyze data by using an autoregressive conditional duration (A…

Multilinear Fourier multipliers related to time–frequency localization

2013

We consider multilinear multipliers associated in a natural way with localization operators. Boundedness and compactness results are obtained. In particular, we get a geometric condition on a subset A⊂R2d which guarantees that, for a fixed synthesis window ψ∈L2(Rd), the family of localization operators Lφ,ψA obtained when the analysis window φ varies on the unit ball of L2(Rd) is a relatively compact set of compact operators.

Uztvertā vecāku pārraudzība, smēķēšanas un/ vai alkohola lietošanas biežums pusaudžiem no pilnām un nepilnām ģimenēm.

2018

Pētījuma mērķis bija izpētīt sakarības starp uztverto vecāku pārraudzību un alkohola lietošanas biežumu pusaudžiem no pilnām un nepilnām ģimenēm. Datu ievākšanai tika izmantota Vecāku uzraudzības aptauja ( Parental Monitoring Scale, Stattin & Kerr, 2009), kas sastāv no 24 jautājumiem, kas atspoguļo vecāku uzraudzības veidus., (t.i., ko vecāki zina, pusaudžu atklātība, kontroles sajūta, vecāku kontrole). Apgalvojumi tiek vērtēti pēc Likerta skalas 5 punktu sistēmā (1- „nekad”, 5- „vienmēr”). Un alkohola lietošanas biežuma aptauja (Youth risk behavior survey. Division of adolescent and school health, CDC, 1993.g.). Attiecīgā aptauja sastāv no 5 jautājumiem. Respondentiem tiek lūgts izvērtēt k…

Frequency domain control based on quantitative feedback theory for vibration suppression in structures equipped with magnetorheological dampers

2009

This is an author-created, un-copyedited version of an article accepted for publication in Smart Materials and Structures. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The definitive publisher authenticated version is available online at http://dx.doi.org/10.1088/0964-1726/18/9/095041 This paper addresses the problem of designing quantitative feedback theory (QFT) based controllers for the vibration reduction in a structure equipped with an MR damper. In this way, the controller is designed in the frequency domain and the natural frequencies of the structure can be directly accounted for in the process. T…

Radiofrekvences identifikācijas izmantošana laika izsekošanai sporta sacensībās

2016

Diplomdarbā tiek analizētas pasīvo RFID etiķešu izmaksu samazinājuma potenciāls kā iespēja biznesa veidošanai. Specifiski, lai skriešanas sacensību “Stirnu Buks” organizatoram varētu piedāvātu izdevīgāku laika izsekošanas tehnoloģiju par pašreizējo ārpakalpojuma sniedzēju - SPORTident. Darba rezultātā tiek secināts, ka ir iespējams piedāvāt pasīvo laika izsekošanas sistēmu lētāk par pašreizējo konkurentu un gūt sākotnēji plānoto peļņu. Tajā pašā laikā atšķirība no konkurenta piedāvātās cenas ir pietiekoši neliela, lai apšaubītu klienta vēlmi mainīt pakalpojuma sniedzēju. Piedāvātā pakalpojuma cenas samazināšana gadījumā mērķa peļņa netiek sasniegta un tiek secināts, ka tādā gadījumā piegādā…

Ar dabas aizsardzību saistīto terminu lietojums uzņēmumu mājas lapu tekstos

2021

Uzņēmumi savās mājas lapās var izmantot ar dabas aizsardzību (DA) saistītus terminus, lai sabiedrība tos uztvertu noteiktā veidā. Šī bakalaura darba mērķis ir analizēt DA terminu lietojumu desmit izvēlētu uzņēmumu mājas lapu tekstos, kas ņemti no piecām dažādām nozarēm. Galvenās pētījuma metodes ir literatūras apskats, absolūtā biežuma analīze un diskursa analīze. Dati parāda, ka automašīnu ražotāji savās mājaslapās izmanto visvairāk DA terminu, savukārt apģērbu firmas izmanto vismazāk DA terminu. Lielākā daļa atrasto DA terminu ir lietvārdi. Tiek secināts, ka uzņēmumus, kas savās mājaslapās lielākoties izmanto DA terminus no „vides risinājumu” kategorijas, var uztvert kā dabai draudzīgākus…

Practical Implementation of a Synchronous PWM Strategy for Low Switching Frequency FOC of im Drives with ATSAM3X8E Microcontroller

2021

This paper presents a practical implementation of synchronous PWM modulation algorithm for an induction motor field oriented control powered by a DC/AC inverter and implemented on a low-cost microcontroller, the ATSAM3X8E. In particular, a simple algorithm, capable to calculate automatically an optimized set of frequency modulation indexes will be presented. Hysteresis bands are also introduced in the algorithm in order to avoid multiple changeovers during modulation index transitions. Experimental tests and their results will be shown and discussed, highlighting the benefits of the present algorithm, such as reduction of current harmonic content, reduction of current ripple and, consequent…

Transmission, infectivity and survival of Diplostomum spathaceum cercariae

2003

The transmission dynamics of the cercariae of Diplostomum spathaceum were investigated under laboratory conditions using cercariae collected from naturally infected Lymnaea stagnalis. Cercariae were kept in a constant temperature of 20 °C and the survival and infectivity to naïve young rainbow trout recorded at 3-h intervals until few cercariae were alive. Mortality initially remained constant but increased rapidly after 20 h. While a model of constant mortality fitted the survival data, an age-dependent model provided a better fit and implied that cercariae tended to carry similar quantities of resources and once these were exhausted the cercariae died. Cercarial infectivity also showed an…