933 resultados para Analog-to-digital converter (ADC)


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In the last decade, an important debate has arisen about the characteristics of today"s students due to their intensive experience as users of ICT. The main belief is that frequent use of technologies in everyday life implies that competent users are able to transfer their digital skills to learning activities. However, empirical studies developed in different countries reveal similar results suggesting that the"digital native" label does not provide evidence of a better use of technology to support learning. The debate has to go beyond the characteristics of the new generation and focus on the implications of being a learner in a digitalised world. This paper is based on the hypothesis that the use of technology to support learning is not related to whether a student belongs to the Net Generation, but that it is mainly influenced by the teaching model. The study compares behaviour and preferences towards ICT use in two groups of university students: face-to-face students and online students. A questionnaire was applied to a sample of students from five universities with different characteristics (one offers online education and four offer face-to-face education with LMS teaching support). Findings suggest that although access to and use of ICT is widespread, the influence of teaching methodology is very decisive. For academic purposes, students seem to respond to the requirements of their courses, programmes, and universities. There is a clear relationship between students" perception of usefulness regarding certain ICT resources and their teachers" suggested uses of technologies. The most highly rated technologies correspond with those proposed by teachers. The study shows that the educational model (face-to-face or online) has a stronger influence on students" perception of usefulness regarding ICT support for learning than the fact of being a digital native.

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Tutkielman tavoitteena oli tutkia, millaista arvoa digitaalinen painatusmenetelmä tuo yrityksen arvoverkostoon. Teoriaosassa tavoite oli rakentaa digitaalipainatuksen arvoverkostoa tutkien kirjallisuutta liittyen arvoketju- ja arvoverkostoajatteluun. Myös aiemmat tutkimukset ja kirjallisuus liittyen digitaalipainatukseen rakensivat osaltaan teoreettisen viitekehyksen muodostumista. Aiemmat tutkimukset digitaalisen painomenetelmän mahdollisuuksista ovat hyvin tekniikkapainotteisia, siksi tämä tutkimus liittyy enemmän kaupallisiin mahdollisuuksiin. Empiirinen osio tutkimuksesta tehtiin kvalitatiivisena case -tutkimuksena, johon sisältyi yksi alayksikkö. Eli tutkittiin yhtä casea, jossa oli kaksi osapuolta. Tutkielma liittyy kiinteästi Stora Enson ja Valion väliseen digipainatus-projektiin, joka käynnistettiin helmikuussa 2001. Tutkielman teemahaastatteluihin valittiin henkilöt tästä projektiryhmästä. Projektiryhmän mielipiteitä ja havaintoja hyödyntäen pyrittiin löytämään tukea ja eroavaisuuksia teoriaosan muodostamaan viitekehykseen ja informaatioon. Empiirinen osuus tuki teoriaosassa esittämiä väittämiä hyvin, mutta myös muutamia uusia havaintoja esiintyi. Tutkimusongelmaan löydettiin monia vastauksia: digitaalipainatus luo arvoa yrityksen jakeluketjuun vähentämällä varastoja ja nopeuttamalla toimituksia. Jäätelöpakkausten markkinointi on aivan uuden haasteen edessä, koska mahdollisuudet kasvavat digitaalipainatuksen myötä huomattavasti. Kartongin valmistajalle arvo tulee parempien tuotteiden kautta, joista saa myös paremman tuoton. Digitaalipainatuksen arvoverkostossa tulee tapahtumaan muutoksia jatkossa, eri osapuolten roolit saattavat muuttua radikaalisti. Kuka hoitaa painatusta ja miten?

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Objective To develop procedures to ensure consistency of printing quality of digital images, by means of hardcopy quantitative analysis based on a standard image. Materials and Methods Characteristics of mammography DI-ML and general purpose DI-HL films were studied through the QC-Test utilizing different processing techniques in a FujiFilm®-DryPix4000 printer. A software was developed for sensitometric evaluation, generating a digital image including a gray scale and a bar pattern to evaluate contrast and spatial resolution. Results Mammography films showed maximum optical density of 4.11 and general purpose films, 3.22. The digital image was developed with a 33-step wedge scale and a high-contrast bar pattern (1 to 30 lp/cm) for spatial resolution evaluation. Conclusion Mammographic films presented higher values for maximum optical density and contrast resolution as compared with general purpose films. The utilized digital processing technique could only change the image pixels matrix values and did not affect the printing standard. The proposed digital image standard allows greater control of the relationship between pixels values and optical density obtained in the analysis of films quality and printing systems.

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In this work parameters of Mg-doped GaN samples were studied using positron annihilation spectroscopy and analyzed. It is shown that gallium vacancies exist in an unintentionally doped sample. Next, the sample with higher concentration of Mg and low growth temperature contains vacancy clusters. In case of low concentration of Mg the growth temperature does not affect the formation of defects. Analog electronics can be replaced by a modern digital device. While promising a high quantity of benefits, the performance of these digitizers requires thorough adjustment. A 14-bit two channel digitizer has been tested in order to achieve better performance than the one of a traditional analog setup, and the adjustment process is described. It has been shown that the digital device is unable to achieve better energy resolution, but it is quite close to the corresponding attribute of the available analog system, which had been used for measurements in Mg-doped GaN.

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The core idea of this Master's Thesis was that five key characteristics – market heterogeneity, sociopolitical governance, chronic shortage of resources, unbranded competition, and inadequate infrastructure – of emerging markets are radically different from the traditional industrialized capitalist society and they will require us to rethink the core assumptions of business-to-business marketing, such as business relationships, marketing communication elements, and digitalization. In this research, Russia is considered to be an emerging market that reflects the aforementioned theoretical characteristics. The research was a qualitative case study and furthermore a collective case study. In the beginning three digital marketing professionals were interviewed to better understand digital B2B marketing. The actual research data was collected through seven structured theme interviews with representatives of the case companies operating in Russia. The selection of case companies included three business consulting companies and four industrial companies. The aim of this qualitative study was to understand and clarify how business marketing exploits digital marketing methods as a part of the chosen business marketing strategy under emerging markets’ special conditions. This objective was divided in three research questions: 1) How the chosen marketing strategy reflects in the business marketing process? 2) How digital marketing communication contributes to business marketing? 3) How are the emerging markets’ characteristics reflected in the business marketing process? The main research findings indicate that digital business-to-business marketing communications can be useful and effective. Moreover, business DMC can be defined and structured in a reasonable way. The company's prevalent marketing paradigm and the chosen marketing strategy reflect in the business marketing process, and in utilizing digital marketing communications. The assumption that emerging markets set an environment with special characteristics for business marketing was supported by the study. However, the business environmental aspects were not considerably disturbing digital B2B marketing, but making it even more reasonable to harness in Russia.

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The Shadow Moiré fringe patterns are level lines of equal depth generated by interference between a master grid and its shadow projected on the surface. In simplistic approach, the minimum error is about the order of the master grid pitch, that is, always larger than 0,1 mm, resulting in an experimental technique of low precision. The use of a phase shift increases the accuracy of the Shadow Moiré technique. The current work uses the phase shifting method to determine the surfaces three-dimensional shape using isothamic fringe patterns and digital image processing. The current study presents the method and applies it to images obtained by simulation for error evaluation, as well as to a buckled plate, obtaining excellent results. The method hands itself particularly useful to decrease the errors in the interpretation of the Moiré fringes that can adversely affect the calculations of displacements in pieces containing many concave and convex regions in relatively small areas.

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Poster at Open Repositories 2014, Helsinki, Finland, June 9-13, 2014

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Presentation at Open Repositories 2014, Helsinki, Finland, June 9-13, 2014

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Presentation at Open Repositories 2014, Helsinki, Finland, June 9-13, 2014

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In this thesis, the main point of interest is the robust control of a DC/DC converter. The use of reactive components in the power conversion gives rise to dynamical effects in DC/DC converters and the dynamical effects of the converter mandates the use of active control. Active control uses measurements from the converter to correct errors present in the converter’s output. The controller needs to be able to perform in the presence of varying component values and different kinds of disturbances in loading and noises in measurements. Such a feature in control design is referred as robustness. This thesis also contains survey of general properties of DC/DC converters and their effects on control design. In this thesis, a linear robust control design method is studied. A robust controller is then designed and applied to the current control of a phase shifted full bridge converter. The experimental results are shown to match simulations.

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In this work, the feasibility of the floating-gate technology in analog computing platforms in a scaled down general-purpose CMOS technology is considered. When the technology is scaled down the performance of analog circuits tends to get worse because the process parameters are optimized for digital transistors and the scaling involves the reduction of supply voltages. Generally, the challenge in analog circuit design is that all salient design metrics such as power, area, bandwidth and accuracy are interrelated. Furthermore, poor flexibility, i.e. lack of reconfigurability, the reuse of IP etc., can be considered the most severe weakness of analog hardware. On this account, digital calibration schemes are often required for improved performance or yield enhancement, whereas high flexibility/reconfigurability can not be easily achieved. Here, it is discussed whether it is possible to work around these obstacles by using floating-gate transistors (FGTs), and analyze problems associated with the practical implementation. FGT technology is attractive because it is electrically programmable and also features a charge-based built-in non-volatile memory. Apart from being ideal for canceling the circuit non-idealities due to process variations, the FGTs can also be used as computational or adaptive elements in analog circuits. The nominal gate oxide thickness in the deep sub-micron (DSM) processes is too thin to support robust charge retention and consequently the FGT becomes leaky. In principle, non-leaky FGTs can be implemented in a scaled down process without any special masks by using “double”-oxide transistors intended for providing devices that operate with higher supply voltages than general purpose devices. However, in practice the technology scaling poses several challenges which are addressed in this thesis. To provide a sufficiently wide-ranging survey, six prototype chips with varying complexity were implemented in four different DSM process nodes and investigated from this perspective. The focus is on non-leaky FGTs, but the presented autozeroing floating-gate amplifier (AFGA) demonstrates that leaky FGTs may also find a use. The simplest test structures contain only a few transistors, whereas the most complex experimental chip is an implementation of a spiking neural network (SNN) which comprises thousands of active and passive devices. More precisely, it is a fully connected (256 FGT synapses) two-layer spiking neural network (SNN), where the adaptive properties of FGT are taken advantage of. A compact realization of Spike Timing Dependent Plasticity (STDP) within the SNN is one of the key contributions of this thesis. Finally, the considerations in this thesis extend beyond CMOS to emerging nanodevices. To this end, one promising emerging nanoscale circuit element - memristor - is reviewed and its applicability for analog processing is considered. Furthermore, it is discussed how the FGT technology can be used to prototype computation paradigms compatible with these emerging two-terminal nanoscale devices in a mature and widely available CMOS technology.

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This thesis regards exhaustion of copyright’s distribution right in intangible transfers of video games. It analyses whether, under the current law of the European Union, the phenomenon of digital exhaustion, especially in relation to games exists. The thesis analyses the consumers’ position in the market for copyright protected goods. It uses video games market as an example of the wider phenomenon of the effect of latest technological developments on consumers. The research conducted for the thesis is mostly legal dogmatic, although also comparative analysis, law and economics and law and technology methods are utilised. The thesis evaluates the effects of the most recent case law of the European Court of Justice to analyse the current state of digital exhaustion. In the analysis of effects that the existence of digital exhaustion has, the thesis uses the consumers’ point of view. The thesis introduces the current state of technology in the field of video games from a legal perspective. Furthermore the thesis analyses the effects on consumers of a scenario that no digital exhaustion exists in the future. Such scenario under the recent European case law at the moment seems realistic. The conclusion of my research is most importantly that the consumer position in the market for digital goods has deteriorated and that the probable exclusion of the exhaustion for digital goods is another piece of evidence of this development. Most importantly however, the state of affairs where no certainty prevails on whether digital exhaustion exists, creates injustice from the consumers’ point of view. Accordingly, acts by EU legislators of the Court of Justice of the European Union are required to clarify the issue.

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RMS measuring device is a nonlinear device consisting of linear and nonlinear devices. The performance of rms measurement is influenced by a number of factors; i) signal characteristics, 2) the measurement technique used and 3) the device characteristics. RMS measurement is not simple, particularly when the signals are complex and unknown. The problem of rms measurement on high crest-factor signals is fully discussed and a solution to this problem is presented in this thesis. The problem of rms measurement is systematically analized and found to have mainly three types of errors: (1) amplitude or waveform error 2) Frequency error and (3) averaging error. Various rms measurement techniques are studied and compared. On the basis of this study the rms -measurement is reclassified three categories: (1) Wave-form-error-free measurement (2) High-frequncy-error measurement and (3) Low-frequency error-free measurement. In modern digital sampled-data systems the signals are complex and waveform-error-free rms measurement is highly appreciated. Among the three basic blocks of rms measuring device the squarer is the most important one. A squaring technique is selected, that permits shaping of the squarer error characteristic in such a way as to achieve waveform-errob free rms measurement. The squarer is designed, fabricated and tested. A hybrid rms measurement using an analog rms computing device and digital display combines the speed of analog techniques and the resolution and ease of measurement of digital techniques. An A/D converter is modified to perform the square-rooting operation. A 10-V rms voltmeter using the developed rms detector is fabricated and tested. The chapters two, three and four analyse the problems involved in rms measurement and present a comparative study of rms computing techniques and devices. The fifth chapter gives the details of the developed rms detector that permits wave-form-error free rms measurement. The sixth chapter, enumerates the the highlights of the thesis and suggests a list of future projects

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The most widely used methods to assess the nitrogen (N) status of winter wheat (Triticum aestivum L.) are the determination of plant total N by combustion, the testing of nitrate in the leaf tissue and the use of SPAD readings. However, due to their labor requirements or high costs these methods can hardly be applied to the huge wheat growing areas of the Northern China Plain. This study therefore examined an alternative method to measure the N status of wheat by using a digital camera to record the visible green light reflected from the plant canopy. The experiment was conducted near Beijing in a multi-factorial field trial with three levels of N. The intensity of green light reflected from the wheat canopy was compared to the total N concentration, to the nitrate concentration of the basal stem, and to the SPAD readings of leaves. The results show significant inverse relationships between greenness intensity, canopy total N, and SPAD readings at booting and flowering. At booting, sap nitrate <2000mgL^-1 was inversely related to greenness intensity and to sap nitrate concentration in the basal stem. At sap nitrate ~2000mgL^-1, the greenness intensity reached a plateau. At booting and flowering, significant inverse relationships between greenness intensity and shoot biomass were found. The results show the potential of the new method to assess the N status of winter wheat.