996 resultados para OPERATING POINT


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A new analytical approach was developed involving cloud point extraction (CPE) and spectrofluorimetric determination of triamterene (TM) in biological fluids. A urine or plasma sample was prepared and adjusted to pH 7, then TM was quickly extracted using CPE, using 0.05% (w/v) of Triton X-114 as the extractant. The main factors that affected the extraction efficiency (the pH of the sample, the Triton X-114 concentration, the addition of salt, the extraction time and temperature, and the centrifugation time and speed) were studied and optimized. The method gave calibration curves for TM with good linearities and correlation coefficients (r) higher than 0.99. The method showed good precision and accuracy, with intra- and inter-assay precisions of less than 8.50% at all concentrations. Standard addition recovery tests were carried out, and the recoveries ranged from 94.7% to 114%. The limits of detection and quantification were 3.90 and 11.7 µg L-1, respectively, for urine and 5.80 and 18.0 µg L-1, respectively, for plasma. The newly developed, environmentally friendly method was successfully used to extract and determine TM in human urine samples.

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In this study, a procedure is developed for cloud point extraction of Pd(II) and Rh(III) ions in aqueous solution using Span 80 (non-ionic surfactant) prior to their determination by flame atomic absorption spectroscopy. This method is based on the extraction of Pd(II) and Rh(III) ions at a pH of 10 using Span 80 with no chelating agent. We investigated the effect of various parameters on the recovery of the analyte ions, including pH, equilibration temperature and time, concentration of Span 80, and ionic strength. Under the best experimental conditions, the limits of detection based on 3Sb for Pd(II) and Rh(III) ions were 1.3 and 1.2 ng mL-1, respectively. Seven replicate determinations of a mixture of 0.5 µg mL-1 palladium and rhodium ions gave a mean absorbance of 0.058 and 0.053 with relative standard deviations of 1.8 and 1.6%, respectively. The developed method was successfully applied to the extraction and determination of the palladium and rhodium ions in road dust and standard samples and satisfactory results were obtained.

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The quantitative structure property relationship (QSPR) for the boiling point (Tb) of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) was investigated. The molecular distance-edge vector (MDEV) index was used as the structural descriptor. The quantitative relationship between the MDEV index and Tb was modeled by using multivariate linear regression (MLR) and artificial neural network (ANN), respectively. Leave-one-out cross validation and external validation were carried out to assess the prediction performance of the models developed. For the MLR method, the prediction root mean square relative error (RMSRE) of leave-one-out cross validation and external validation was 1.77 and 1.23, respectively. For the ANN method, the prediction RMSRE of leave-one-out cross validation and external validation was 1.65 and 1.16, respectively. A quantitative relationship between the MDEV index and Tb of PCDD/Fs was demonstrated. Both MLR and ANN are practicable for modeling this relationship. The MLR model and ANN model developed can be used to predict the Tb of PCDD/Fs. Thus, the Tb of each PCDD/F was predicted by the developed models.

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The aim of this thesis is to investigate the thermal loading of medium voltage three-level NPC inverter’s semiconductor IGCT switches in different operation points. The objective is to reach both a fairly accurate off-line simulation program and also so simple a simulation model that its implementation into an embedded system could be reasonable in practice and a real time use should become feasible. Active loading limitation of the inverter can be realized with a thermal model which is practical in a real time use. Determining of the component heating has been divided into two parts; defining of component losses and establishing the structure of a thermal network. Basics of both parts are clarified. The simulation environment is Matlab-Simulink. Two different models are constructed – a more accurate one and a simplified one. Potential simplifications are clarified with the help of the first one. Simplifications are included in the latter model and the functionalities of both models are compared. When increasing the calculation time step a decreased number of considered components and time constants of the thermal network can be used in the simplified model. Heating of a switching component is dependent on its topological position and inverter’s operation point. The output frequency of the converter defines mainly which one of the switching components is – because of its losses and heating – the performance limiting component of the converter. Comparison of results given by different thermal models demonstrates that with larger time steps, describing of fast occurring switching losses becomes difficult. Generally articles and papers dealing with this subject are written for two-level inverters. Also inverters which apply direct torque control (DTC) are investigated rarely from the heating point of view. Hence, this thesis completes the former material.

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Suomessa rautatiellä käytetään muutamia tuhansia sähköisesti ohjattavia vaihteita, joiden toiminta varmistetaan määräajoin tehtävillä huolloilla. Työssä on tutkittu, onko kehitteillä olevalla vaihteenohjaimella mahdollista mitata ja analysoida vaihteen kunnonvalvontaan liittyviä suureita. Tutkimuksessa on tutustuttu rautatietekniikkaan sekä vaihdetta ohjaavaan vaihteenkääntölaitteeseen. Tutkimuksen perusteella on kehitetty sulautettuun järjestelmään perustuva mittaus- ja analysointijärjestelmäsovellus, joka tekee mittauksia, havaintoja ja johtopäätöksiä vaihteen toiminnasta. Mittaukset on suoritettu moottoria ohjaavista johtimista ja mittaustulokset on tallennettu analysointia ja jatkokäsittelyä varten. Ohjelmiston toimintaa on varmistettu mittauksilla sekä laboratorio-olosuhteissa että oikealla vaihteella testausympäristössä. Saatujen tulosten perusteella voidaan todeta, että kehitetyllä laitteistolla on mahdollista toteuttaa vaihdetta diagnosoivia mittauksia riittävän laadukkaasti ja tarkasti. Työssä kehitetty järjestelmäalusta soveltuu käytettäväksi vaihteen diagnostiikan jatkokehittämiselle.

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This paper studies the relationship of earnings management and investors. Analysis of incentives reveals that most of them are opportunistic in nature. Unfortunately the investor would need insider information to distinguish between different forms of earnings management. Investors in some countries seem to devalue earnings when government body has signaled that earnings management might be involved, unfortunately without a clear signal the behavior seems reverse among non-institutional investors.

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A model to estimate damage caused by gray leaf spot of corn (Cercospora zea-maydis) was developed from experimental field data gathered during the summer seasons of 2000/01 and during the second crop season [January-seedtime] of 2001, in the southwest of Goiás state. Three corn hybrids were grown over two seasons and on two sites, resulting in 12 experimental plots. A disease intensity gradient (lesions per leaf) was generated through application, three times over the season, of five different doses of the fungicide propiconazol. From tasseling onward, disease intensity on the ear leaf (El), and El - 1, El - 2, El + 1, and El + 2, was evaluated weekly. A manual harvest at the physiological ripening stage was followed by grain drying and cleaning. Finally, grain yield in kg.ha-1 was estimated. Regression analysis, performed between grain yield and all combinations of the number of lesions on each leaf type, generated thirty linear equations representing the damage function. To estimate losses caused by different disease intensities at different corn growth stages, these models should first be validated. Damage coefficients may be used in determining the economic damage threshold.

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In the current economy situation companies try to reduce their expenses. One of the solutions is to improve the energy efficiency of the processes. It is known that the energy consumption of pumping applications range from 20 up to 50% of the energy usage in the certain industrial plants operations. Some studies have shown that 30% to 50% of energy consumed by pump systems could be saved by changing the pump or the flow control method. The aim of this thesis is to create a mobile measurement system that can calculate a working point position of a pump drive. This information can be used to determine the efficiency of the pump drive operation and to develop a solution to bring pump’s efficiency to a maximum possible value. This can allow a great reduction in the pump drive’s life cycle cost. In the first part of the thesis, a brief introduction in the details of pump drive operation is given. Methods that can be used in the project are presented. Later, the review of available platforms for the project implementation is given. In the second part of the thesis, components of the project are presented. Detailed description for each created component is given. Finally, results of laboratory tests are presented. Acquired results are compared and analyzed. In addition, the operation of created system is analyzed and suggestions for the future development are given.

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The maximum realizable power throughput of power electronic converters may be limited or constrained by technical or economical considerations. One solution to this problemis to connect several power converter units in parallel. The parallel connection can be used to increase the current carrying capacity of the overall system beyond the ratings of individual power converter units. Thus, it is possible to use several lower-power converter units, produced in large quantities, as building blocks to construct high-power converters in a modular manner. High-power converters realized by using parallel connection are needed for example in multimegawatt wind power generation systems. Parallel connection of power converter units is also required in emerging applications such as photovoltaic and fuel cell power conversion. The parallel operation of power converter units is not, however, problem free. This is because parallel-operating units are subject to overcurrent stresses, which are caused by unequal load current sharing or currents that flow between the units. Commonly, the term ’circulatingcurrent’ is used to describe both the unequal load current sharing and the currents flowing between the units. Circulating currents, again, are caused by component tolerances and asynchronous operation of the parallel units. Parallel-operating units are also subject to stresses caused by unequal thermal stress distribution. Both of these problemscan, nevertheless, be handled with a proper circulating current control. To design an effective circulating current control system, we need information about circulating current dynamics. The dynamics of the circulating currents can be investigated by developing appropriate mathematical models. In this dissertation, circulating current models aredeveloped for two different types of parallel two-level three-phase inverter configurations. Themodels, which are developed for an arbitrary number of parallel units, provide a framework for analyzing circulating current generation mechanisms and developing circulating current control systems. In addition to developing circulating current models, modulation of parallel inverters is considered. It is illustrated that depending on the parallel inverter configuration and the modulation method applied, common-mode circulating currents may be excited as a consequence of the differential-mode circulating current control. To prevent the common-mode circulating currents that are caused by the modulation, a dual modulator method is introduced. The dual modulator basically consists of two independently operating modulators, the outputs of which eventually constitute the switching commands of the inverter. The two independently operating modulators are referred to as primary and secondary modulators. In its intended usage, the same voltage vector is fed to the primary modulators of each parallel unit, and the inputs of the secondary modulators are obtained from the circulating current controllers. To ensure that voltage commands obtained from the circulating current controllers are realizable, it must be guaranteed that the inverter is not driven into saturation by the primary modulator. The inverter saturation can be prevented by limiting the inputs of the primary and secondary modulators. Because of this, also a limitation algorithm is proposed. The operation of both the proposed dual modulator and the limitation algorithm is verified experimentally.

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Tässä tutkielmassa korostuu Euroopan sisäinen kulttuurillinen erilaisuus ja sen vaatimukset Suomessa toimiville monikansallisille organisaatioille. Eurooppalaista johtamista on tutkittu jo vuosikymmenten ajan, mutta erityisesti suomalaisesta, Suomessa työskentelevien eurooppalaisten näkökulmasta ei vastaavaa tutkimusta tiettävästi ole aiemmin tehty. Tutkimuksen tavoitteena on selvittää suomalaisen kulttuurin ja johtajuuden arvoeroja muiden Euroopan Unionin maiden kansalaisten näkökulmasta. Pohjois-Euroopan maista tutkimuksessa on mukana edustajia Ruotsista, Tanskasta ja Hollannista. Keski-Euroopan maista edustusta löytyy Saksasta ja Itävallasta, kun Etelä-Eurooppaa edustavat ranskalaiset ja italialaiset henkilöt. Itäisestä Euroopasta mukana on latvialaisia henkilöitä ja anglo-Euroopasta britannialaisia. Tutkimus kartoittaa tutkimukseen mukaan otettujen maiden yhteisö- ja johtamiskulttuurillisia törmäyskohtia suomalaisen kulttuurin kanssa, jotta Suomessa toimivat monikansalliset työyhteisöt löytäisivät yhä parempia strategioita eurooppalaisen ihmispääoman, eurooppalaisten työntekijöiden ja näiden osaamisen, johtamiseksi ja monikansallisen yhteisön toimivuuden ymmärtämiseksi ja parantamiseksi. Näitä törmäyskohtia tarkastellaan empiirisesti Hofsteden (1984) kulttuuridimensioiden, Housen ym. (1999) GLOBE-tutkimuksen ja Koopmanin ym. (1999) johtajuusulottuvuuksien avulla. Tutkimusaineisto koostuu Internet-pohjaisesta kyselystä, joka suoritettiin keväällä 2010. Siihen osallistui 75 Suomessa työskentelevää Euroopan Unionin kansalaista. Analysointimenetelmänä tutkimuksessa käytetään klusterointia, keskiarvoistuksia, Kruskall Wallisin testiä ja sisällönanalyysiä tukemaan määrällisen analyysin tuloksia ja tuomaan esiin siitä poikkeavia havaintoja. Tutkimuksen ytimessä on johtamiskulttuurilliset erot, joista tehdään laajempaa analyysiä edellä mainituin keinoin. Yhteisökulttuurillisia eroja havainnoidaan tutkimuskyselyyn perustuvien väittämien perusteella tehtyjen histogrammien avulla. Tutkimuksen tulokset osoittavat, että maantieteellinen, uskonnollinen tai poliittinen läheisyys eivät määritä kulttuurillista läheisyyttä tai johda kulttuurilliseen sopeutumiseen. Poliittinen raja kahden naapurin välillä saattaa johtaa saman asian kokemiseen kahdella täysin eri tavalla. Lisäksi tuloksista käy ilmi, että yhteisökulttuurilliset ja johtamiskulttuurilliset arvot eivät välttämättä kulje käsikkäin Suomessa työskentelevien eurooppalaisten näkökulmasta. Yleisinä kulttuurillisina kipukohtina tutkimuksessa nousee esiin suomalaisen kulttuurin sosiaalisuuden ja kommunikaation puutteellisuus, toisaalta suomalaiseen kulttuuriin sopeutumista helpottaa suomalainen rehellisyys ja suoruus. Johtamiskulttuurillisina haasteina eurooppalaiset kokevat suomalaisen tyyppijohtajan kyvyttömyyden riskien ottamiseen ja kannustusmenetelmien puutteet. Tämän lisäksi tutkimuksessa tulee ilmi useita tiettyihin kansallisuuksiin liittyviä törmäyskohtia. Tutkimus on nähtävä tämän hetken kuvauksena. Kulttuuritutkimus sisältää monia tekijöitä, jotka ovat jatkuvassa muutoksessa ja lisäksi hyvin subjektiivisia. Kulttuurijohtajuus merkitsee kuitenkin nyt ja tulevaisuudessa kykyä olla innovatiivinen, joustava ja herkkä sosiaalisille merkityksille.

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ABSTRACTA model to estimate yield loss caused by Asian soybean rust (ASR) (Phakopsora pachyrhizi) was developed by collecting data from field experiments during the growing seasons 2009/10 and 2010/11, in Passo Fundo, RS. The disease intensity gradient, evaluated in the phenological stages R5.3, R5.4 and R5.5 based on leaflet incidence (LI) and number of uredinium and lesions/cm2, was generated by applying azoxystrobin 60 g a.i/ha + cyproconazole 24 g a.i/ha + 0.5% of the adjuvant Nimbus. The first application occurred when LI = 25% and the remaining ones at 10, 15, 20 and 25-day intervals. Harvest occurred at physiological maturity and was followed by grain drying and cleaning. Regression analysis between the grain yield and the disease intensity assessment criteria generated 56 linear equations of the yield loss function. The greatest loss was observed in the earliest growth stage, and yield loss coefficients ranged from 3.41 to 9.02 kg/ha for each 1% LI for leaflet incidence, from 13.34 to 127.4 kg/ha/1 lesion/cm2 for lesion density and from 5.53 to 110.0 kg/ha/1 uredinium/cm2 for uredinium density.

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Viilunkuivaus vaneriteollisuudessa on energiaintensiivinen prosessi, josta syntyvä hukkalämpö kannattaa ottaa talteen ja hyödyntää. Työ käsittelee erilaisten lämmöntalteenottovariaatioiden tuotteistusta ja kannattavuutta, sekä sisältää laitteiston riskianalyysin. Aiemman asiakaskohtaisen räätälöinnin sijaan, laitteiston modulaarinen tuoterakenne on otettava tuotteistuksen lähtökohdaksi. Modulaarisen tuoterakenteen ansiosta erilaisiin asiakastarpeisiin pystytään vastaamaan aiempaa tehokkaammin, kiitos erilaisten variaatioiden. Standardien ja yhtenäisten rajapintojen myötä muun muassa suunnittelua, projektinhoito ja myyntiä saadaan tehostettua. Lämmöntalteenottoratkaisuille luodaan kolme eri varustelutasoa: perus, korkea ja luksus. Näillä eri varianteilla pystytään vastamaan entistä kattavammin eri markkina-alueiden asiakastarpeisiin. Kannattavuuslaskelmat todistavat, että lämmöntalteenoton avulla saadaan merkittäviä energiasäästöjä ja eri laitteistovariaatiot maksavat itsensä erittäin nopeasti takaisin, vaikka esimerkiksi sähköenergian hinta nousisi radikaalisti. Lämmöntalteenoton voidaankin katsoa olevan aina erittäin kannattavaa. Laitteistosta on tunnistettu myös tekniset riskit, joihin on puututtava välittömästi sekä lukuisia toimenpide-ehdotuksia, joiden avulla laitteiston tuomintaa voidaan tehostaa ja muuttaa turvallisemmaksi. Riskianalyysi antaa myös suuntaviivoja tuotteistukselle sekä laitteiston huolto- ja käyttöohjeistolle.

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The concept of open innovation has recently gained widespread attention, and is particularly relevant now as many firms endeavouring to implement open innovation, face different sets of challenges associated with managing it. Prior research on open innovation has focused on the internal processes dealing with open innovation implementation and the organizational changes, already taking place or yet required in companies order to succeed in the global open innovation market. Despite the intensive research on open innovation, the question of what influences its adoption by companies in different contexts has not received much attention in studies. To fill this gap, this thesis contribute to the discussion on open innovation influencing factors by bringing in the perspective of environmental impacts, i.e. gathering data on possible sources of external influences, classifying them and testing their systemic impact through conceptual system dynamics simulation model. The insights from data collection and conceptualization in modelling are used to answer the question of how the external environment affects the adoption of open innovation. The thesis research is presented through five research papers reflecting the method triangulation based study (conducted at initial stage as case study, later as quantitative analysis and finally as system dynamics simulation). This multitude of methods was used to collect the possible external influence factors and to assess their impact (on positive/negative scale rather than numerical). The results obtained throughout the thesis research bring valuable insights into understanding of open innovation influencing factors inside a firm’s operating environment, point out the balance required in the system for successful open innovation performance and discover the existence of tipping point of open innovation success when driven by market dynamics and structures. The practical implications on how firms and policy-makers can leverage environment for their potential benefits are offered in the conclusions.

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In order to verify Point-Centered Quarter Method (PCQM) accuracy and efficiency, using different numbers of individuals by per sampled area, in 28 quarter points in an Araucaria forest, southern Paraná, Brazil. Three variations of the PCQM were used for comparison associated to the number of sampled individual trees: standard PCQM (SD-PCQM), with four sampled individuals by point (one in each quarter), second measured (VAR1-PCQM), with eight sampled individuals by point (two in each quarter), and third measuring (VAR2-PCQM), with 16 sampled individuals by points (four in each quarter). Thirty-one species of trees were recorded by the SD-PCQM method, 48 by VAR1-PCQM and 60 by VAR2-PCQM. The level of exhaustiveness of the vegetation census and diversity index showed an increasing number of individuals considered by quadrant, indicating that VAR2-PCQM was the most accurate and efficient method when compared with VAR1-PCQM and SD-PCQM.