24 resultados para linear feedback control


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Usingof belt for high precision applications has become appropriate because of the rapid development in motor and drive technology as well as the implementation of timing belts in servo systems. Belt drive systems provide highspeed and acceleration, accurate and repeatable motion with high efficiency, long stroke lengths and low cost. Modeling of a linear belt-drive system and designing its position control are examined in this work. Friction phenomena and position dependent elasticity of the belt are analyzed. Computer simulated results show that the developed model is adequate. The PID control for accurate tracking control and accurate position control is designed and applied to the real test setup. Both the simulation and the experimental results demonstrate that the designed controller meets the specified performance specifications.

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Taajuudenmuuttajan kytkennän synnyttämä nopea jännitemuutos aiheuttaa pitkään moottorikaapeliin sähköisen värähtelyilmiön. Ilmiö on tullut erityisesti esille uusien nopeasti kytkevien puolijohdetehokytkimien ilmestyttyä markkinoille. Taajuudenmuuttajan lähtöön asennettu jännitteen nousunopeutta rajoittava suodin vähentää kaapelivärähtelyä, mutta riittävän pitkässä kaapelissa värähtely on voimakasta lähtösuotimesta huolimatta. Kaapelivärähtelyilmiön seurauksena moottorikaapelin taajuudenmuuttajan puoleiseen päähän syntyy voimakas virtavärähtely ja moottorin puoleiseen päähän voimakas jännitevärähtely. Sähkökäyttöjen vektorisäätöalgoritmit tekevät ohjauspäätöksiä moottorikaapelin taajuudenmuuttajan päästä tehtyjen virtamittausten perusteella. Säädön päätösväli on niin lyhyt, että kaapelin virtavärähtely ehtii häiritä säädön toimintaa. Tässä työssä on esitetty kaapelivärähtelyä kuvaava taajuudenmuuttajan lähtösuotimen huomioon ottava siirtofunktioperustainen matemaattinen malli. Mallin avulla kaapelivärähtelyilmiötä voi analysoida lineaarisen säätöteorian menetelmillä. Virtavärähtelyn moottorisäätöön tuomiin ongelmiin ratkaisuksi on esitetty virran mittasignaalin käsittelemistä analogisella ja digitaalisella suotimella. Simulointitulosten perusteella ratkaisua voidaan pitää toimivana. Lopuksi esitetään, kuinka avaruusvektoriteorian mukaista induktiomoottorimallia ja kaapelivärähtelymallia voidaan simuloida yhdessä.

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Tutkimuksen tavoitteena oli selvittää, miten järjestetään yritysmarkkinoinnin seurantamalli sekä seurannan tietojärjestelmätuki. Erityistä huomiota kiinnitettiin markkinoinnin seurannan ja liiketoimintastrategian kytkökseen. Tutkimusmenetelmänä käytettiin case-tutkimusta. Käsittely oli lineaaris-analyyttinen. Markkinoinnin seurannan tietojärjestelmätuen kehittämisen osalta tutkimus omaa myös jonkin verran systeemianalyyttisiä piirteitä. Case-tutkimuksen tiedonhankinnassa käytettiin yrityksen markkinointihenkilöille jaettua kyselytutkimusta. Markkinoinnin seuranta jaoteltiin strategisen tason ja operatiivisen tason seurantaan. Tutkimuksessa todettiin, että liiketoiminnan kilpailuympäristö, valittu kilpailustrategia ja yrityksen elinkaariasema vaikuttavat liiketoimintastrategiaan ja sitä kautta markkinoinnin seurannan järjestämiseen ja että markkinoinnin strategisen tason seurannan tavoitteena on varmistaa, että markkinointitoiminta toteuttaa valittua liiketoimintastrategiaa. Markkinoinnin operatiivisen tason seurannan tehtäväksi todettiin yrityksen markkinointitoiminnan myynnillisten sekä taloudellisten tulosten, sekä kannattavuuden ja tehokkuuden seuranta ja raportointi. Yritysmarkkinoinnin strategisen tason seurantaan soveltuu parhaiten eteenpäinkytkentäinen, tavoiteltavia tuloksia edeltävien muutosten seurantaan keskittyvä malli. Markkinoinnin operatiiivisen tason seurantaan soveltuu laajan markkinoinnin seurannan perusmittariston sisältävä malli, jolla voidaan palvella nykyisiä seurannan tarpeita ja laatia tarvittaessa uusia seurantakokonaisuuksia. Yritysmarkkinoinnin seurannan tietojärjestelmätuen järjestämiseen soveltuu parhaiten asiakastietokantapohjainen tietojärjestelmämalli. Näin voidaan hallita asiakkaaseen kohdistetut markkinointitoimenpiteet sekä niiden seuranta. Case-tutkimus vahvisti tarpeen kehittää kokonaisvaltainen suunnitelma markkinoinnin strategisen ja operatiivisen tason seurannasta sekä sitä tukevista tietojärjestelmistä. Ilman kokonaissunnitelmaa seuranta muodostuu organisaatioyksiköittäin ja seuranta-alueittain epätasaiseksi, eikä yrityksen asemasta markkinoilla ole muodostettavissa kokonaiskuvaa.

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Broadcasting systems are networks where the transmission is received by several terminals. Generally broadcast receivers are passive devices in the network, meaning that they do not interact with the transmitter. Providing a certain Quality of Service (QoS) for the receivers in heterogeneous reception environment with no feedback is not an easy task. Forward error control coding can be used for protection against transmission errors to enhance the QoS for broadcast services. For good performance in terrestrial wireless networks, diversity should be utilized. The diversity is utilized by application of interleaving together with the forward error correction codes. In this dissertation the design and analysis of forward error control and control signalling for providing QoS in wireless broadcasting systems are studied. Control signaling is used in broadcasting networks to give the receiver necessary information on how to connect to the network itself and how to receive the services that are being transmitted. Usually control signalling is considered to be transmitted through a dedicated path in the systems. Therefore, the relationship of the signaling and service data paths should be considered early in the design phase. Modeling and simulations are used in the case studies of this dissertation to study this relationship. This dissertation begins with a survey on the broadcasting environment and mechanisms for providing QoS therein. Then case studies present analysis and design of such mechanisms in real systems. The mechanisms for providing QoS considering signaling and service data paths and their relationship at the DVB-H link layer are analyzed as the first case study. In particular the performance of different service data decoding mechanisms and optimal signaling transmission parameter selection are presented. The second case study investigates the design of signaling and service data paths for the more modern DVB-T2 physical layer. Furthermore, by comparing the performances of the signaling and service data paths by simulations, configuration guidelines for the DVB-T2 physical layer signaling are given. The presented guidelines can prove useful when configuring DVB-T2 transmission networks. Finally, recommendations for the design of data and signalling paths are given based on findings from the case studies. The requirements for the signaling design should be derived from the requirements for the main services. Generally, these requirements for signaling should be more demanding as the signaling is the enabler for service reception.

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The purpose of this doctoral thesis is to widen and develop our theoretical frameworks for discussion and analyses of feedback practices in management accounting, particularly shedding light on its formal and informal aspects. The concept of feedback in management accounting has conventionally been analyzed within cybernetic control theory, in which feedback flows as a diagnostic or comparative loop between measurable outputs and pre-set goals (see e.g. Flamholtz et al. 1985; Flamholtz 1996, 1983), i.e. as a formal feedback loop. However, the everyday feedback practices in organizations are combinations of formal and informal elements. In addition to technique-driven feedback approaches (like budgets, measurement, and reward systems) we could also categorize social feedback practices that managers see relevant and effective in the pursuit of organizational control. While cybernetics or control theories successfully capture rational and measured aspects of organizational performance and offer a broad organizational context for the analysis, many individual and informal aspects remain vague and isolated. In order to discuss and make sense of the heterogeneous field of interpretations of formal and informal feedback, both in theory and practice, dichotomous approaches seem to be insufficient. Therefore, I suggest an analytical framework of formal and informal feedback with three dimensions (3D’s): source, time, and rule. Based on an abductive analysis of the theoretical and empirical findings from an interpretive case study around a business unit called Division Steelco, the 3Dframework and formal and informal feedback practices are further elaborated vis-á-vis the four thematic layers in the organizational control model by Flamholtz et al. (1985; Flamholtz 1996, 1983): core control system, organizational structure, organizational culture, and external environment. Various personal and cultural meanings given to the formal and informal feedback practices (“feedback as something”) create multidimensional interpretative contexts. Multidimensional frameworks aim to capture and better understand both the variety of interpretations and their implications to the functionality of feedback practices, important in interpretive research.

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Commercially available haptic interfaces are usable for many purposes. However, as generic devices they are not the most suitable for the control of heavy duty mobile working machines like mining machines, container handling equipment and excavators. Alternative mechanical constructions for a haptic controller are presented and analysed. A virtual reality environment (VRE) was built to test the proposed haptic controller mechanisms. Verification of an electric motor emulating a hydraulic pump in the electro-hydraulic system of a mobile working machine is carried out. A real-time simulator using multi-body-dynamics based software with hardware-in-loop (HIL) setup was used for the tests. Recommendations for further development of a haptic controller and emulator electric motor are given.

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The aim of this three phase study was to develop quality of radiotherapy care by the e-Feedback knowledge of radiotherapy -intervention (e-Re-Know). In Phase I, the purpose was to describe the quality of radiotherapy care and its deficits experienced by cancer patients. Based on the deficits in patient education in Phase II, the purpose was to describe cancer patients’ e-knowledge expectations in radiotherapy. In Phase III, the purpose was to develop and evaluate the outcomes of the e-Re-Know among breast cancer patients. The ultimate aim was to develop radiotherapy care to support patients’ empowerment with patient e-education. In Phase I (2004-2005), the descriptive design was used, and 134 radiotherapy patients evaluated their experiences by Good Nursing Care Scale for Patients (GNCS-P) in the middle of RT period. In Phase II (2006-2008), the descriptive longitudinal design was used and 100 radiotherapy patients’ e-knowledge expectations of RT were evaluated using open-ended questionnaire developed for this study before commencing first RT, in the middle of the treatment, and concluding RT period. In Phase III, firstly (2009-2010), the e-Re-Know intervention, i.e. knowledge test and feedback, was developed in terms of empowering knowledge and implemented with e-feedback approach based on literature and expert reviews. Secondly (2011-2014), the randomized controlled study was used to evaluate the e-Re-Know. Breast cancer patients randomized to either the intervention group (n=65) receiving the e-Re-Know by e-mail before commencing first RT and standard education or the control group (n=63) receiving standard education. The data were collected before commencing first RT, concluding last RT and 3 months after last RT using RT Knowledge Test, Spielberger’s State Trait Inventory (STAI) and Functional Assessment of Cancer Therapy - Breast (FACT-B) –instruments. Data were analyzed using statistical methods and content analysis. The study showed radiotherapy patients experienced quality of care high. However, there were deficits in patient education. Furthermore, radiotherapy patients’ multidimensional e-knowledge expectations through Internet covered mainly bio-physiological and functional knowledge. Thus, the e-Re-Know was developed and evaluated. The study showed when breast cancer patients’ carried out the e-Re-Know their knowledge of side effects self-care was significantly increased and quality of life (QOL) significantly improved in line with decrease in anxiety from time before radiotherapy period to three months after. In addition, the e-Re-Know has potential to have positive effects on anxiety and QOL, regardless of patient characteristics or knowledge level. The results support the theory of empowering patient education suggesting that empowerment can be supported by confirming patients’ understanding of own knowledge level. In summary, the e-Feedback knowledge of radiotherapy (e-Re-Know) intervention can be recommended in development of quality of radiotherapy care experienced by breast cancer patients. Further research is needed to assess and develop patient-centred quality of care by patient education among cancer patients.

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Concentrated solar power (CSP) is a renewable energy technology, which could contribute to overcoming global problems related to pollution emissions and increasing energy demand. CSP utilizes solar irradiation, which is a variable source of energy. In order to utilize CSP technology in energy production and reliably operate a solar field including thermal energy storage system, dynamic simulation tools are needed in order to study the dynamics of the solar field, to optimize production and develop control systems. The object of this Master’s Thesis is to compare different concentrated solar power technologies and configure a dynamic solar field model of one selected CSP field design in the dynamic simulation program Apros, owned by VTT and Fortum. The configured model is based on German Novatec Solar’s linear Fresnel reflector design. Solar collector components including dimensions and performance calculation were developed, as well as a simple solar field control system. The preliminary simulation results of two simulation cases under clear sky conditions were good; the desired and stable superheated steam conditions were maintained in both cases, while, as expected, the amount of steam produced was reduced in the case having lower irradiation conditions. As a result of the model development process, it can be concluded, that the configured model is working successfully and that Apros is a very capable and flexible tool for configuring new solar field models and control systems and simulating solar field dynamic behaviour.