992 resultados para Machine theory.


Relevância:

20.00% 20.00%

Publicador:

Resumo:

In this article I intend to show that certain aspects of A.N. Whitehead's philosophy of organism and especially his epochal theory of time, as mainly exposed in his well-known work Process and Reality, can serve in clarify the underlying assumptions that shape nonstandard mathematical theories as such and also as metatheories of quantum mechanics. Concerning the latter issue, I point to an already significant research on nonstandard versions of quantum mechanics; two of these approaches are chosen to be critically presented in relation to the scope of this work. The main point of the paper is that, insofar as we can refer a nonstandard mathematical entity to a kind of axiomatical formalization essentially 'codifying' an underlying mental process indescribable as such by analytic means, we can possibly apply certain principles of Whitehead's metaphysical scheme focused on the key notion of process which is generally conceived as the becoming of actual entities. This is done in the sense of a unifying approach to provide an interpretation of nonstandard mathematical theories as such and also, in their metatheoretical status, as a formalization of the empirical-experimental context of quantum mechanics.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The effectiveness of water removal on press section is very important for a paper and board machine’s functioning, efficiency and economy. Today, the most effective method for wet pressing is shoe press technology. Metso has carried out a number of studies concerning anew type of water removal method for a press section, which has also been patented. These studies include rough sketches and some test runs. These issues form the basis of this thesis. The objective of this work was to gather together information for a new and enhanced waterremoval method for a press section by studying the functioning of the device andcarrying out test runs. This method is referred to here as Hydronip. The main goal was tobuild a functional test site which fulfills all the necessary requirements and has all thenecessary information gathering devices. The design process was carried out by emphasizing the safety aspects. The goal was also to gather together information about the nip structure in running conditions, the seal function, and to carry out the nip tests with paper or board wads. This thesis consists of a theory part, the design and construction of the test site, and carrying out test runs through information gathering. The theory part consists of the principals of water removal from a press section, Hydronip construction, and the requirements for the test place. The safety aspects were taken into account especially in test runs, but also in the assembly stages. The design and construction of the test site includes the selection of equipment and surroundings that are needed for managing the test runs in the best possible way at certain premises. The test site included the equipment that was already on the premises. Some equipment could be used as it was but some equipment had to be manufactured or modified from existing equipment. A functional test site with information gathering devices was accomplished as a result of thethesis. Test runs demonstrated that the Hydronip concept is, at least on a small scale,functional. Short-term tests for seal functioning showed that the seal can be lubricatedsufficiently under different kinds of nip load situations. Wad tests demonstrated that the metal belt is durable against different sizes of external particles. The seal also endured wad tests even though the pressure impacts impaired the lubrication. MTS tests showing dry content increases, combined with a rough cost calculation and the basic function of the machine in test runs, show that with some further study Hydronip could be a promising new product for water removal from a paper or board machine’s press section.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Min avhandling behandlar hur oordnade material leder elektrisk ström. Bland materialen som studeras finns ledande polymerer, d.v.s. plaster som leder ström, och mer allmänt organiska halvledare. Av de här materialen har man kunnat bygga elektroniska komponenter, och man hoppas på att kunna trycka hela kretsar av organiska material. För de här tillämpningarna är det viktigt att förstå hur materialen själva leder elektrisk ström. Termen oordnade material syftar på material som saknar kristallstruktur. Oordningen gör att elektronernas tillstånd blir lokaliserade i rummet, så att en elektron i ett visst tillstånd är begränsad t.ex. till en molekyl eller ett segment av en polymer. Det här kan jämföras med kristallina material, där ett elektrontillstånd är utspritt över hela kristallen (men i stället har en väldefinierad rörelsemängd). Elektronerna (eller hålen) i det oordnade materialet kan röra sig genom att tunnelera mellan de lokaliserade tillstånden. Utgående från egenskaperna för den här tunneleringsprocessen, kan man bestämma transportegenskaperna för hela materialet. Det här är utgångspunkten för den så kallade hopptransportmodellen, som jag har använt mig av. Hopptransportmodellen innehåller flera drastiska förenklingar. Till exempel betraktas elektrontillstånden som punktformiga, så att tunneleringssannolikheten mellan två tillstånd endast beror på avståndet mellan dem, och inte på deras relativa orientation. En annan förenkling är att behandla det kvantmekaniska tunneleringsproblemet som en klassisk process, en slumpvandring. Trots de här grova approximationerna visar hopptransportmodellen ändå många av de fenomen som uppträder i de verkliga materialen som man vill modellera. Man kan kanske säga att hopptransportmodellen är den enklaste modell för oordnade material som fortfarande är intressant att studera. Man har inte hittat exakta analytiska lösningar för hopptransportmodellen, därför använder man approximationer och numeriska metoder, ofta i form av datorberäkningar. Vi har använt både analytiska metoder och numeriska beräkningar för att studera olika aspekter av hopptransportmodellen. En viktig del av artiklarna som min avhandling baserar sig på är att jämföra analytiska och numeriska resultat. Min andel av arbetet har främst varit att utveckla de numeriska metoderna och applicera dem på hopptransportmodellen. Därför fokuserar jag på den här delen av arbetet i avhandlingens introduktionsdel. Ett sätt att studera hopptransportmodellen numeriskt är att direkt utföra en slumpvandringsprocess med ett datorprogram. Genom att föra statisik över slumpvandringen kan man beräkna olika transportegenskaper i modellen. Det här är en så kallad Monte Carlo-metod, eftersom själva beräkningen är en slumpmässig process. I stället för att följa rörelsebanan för enskilda elektroner, kan man beräkna sannolikheten vid jämvikt för att hitta en elektron i olika tillstånd. Man ställer upp ett system av ekvationer, som relaterar sannolikheterna för att hitta elektronen i olika tillstånd i systemet med flödet, strömmen, mellan de olika tillstånden. Genom att lösa ekvationssystemet fås sannolikhetsfördelningen för elektronerna. Från sannolikhetsfördelningen kan sedan strömmen och materialets transportegenskaper beräknas. En aspekt av hopptransportmodellen som vi studerat är elektronernas diffusion, d.v.s. deras slumpmässiga rörelse. Om man betraktar en samling elektroner, så sprider den med tiden ut sig över ett större område. Det är känt att diffusionshastigheten beror av elfältet, så att elektronerna sprider sig fortare om de påverkas av ett elektriskt fält. Vi har undersökt den här processen, och visat att beteendet är väldigt olika i endimensionella system, jämfört med två- och tredimensionella. I två och tre dimensioner beror diffusionskoefficienten kvadratiskt av elfältet, medan beroendet i en dimension är linjärt. En annan aspekt vi studerat är negativ differentiell konduktivitet, d.v.s. att strömmen i ett material minskar då man ökar spänningen över det. Eftersom det här fenomenet har uppmätts i organiska minnesceller, ville vi undersöka om fenomenet också kan uppstå i hopptransportmodellen. Det visade sig att det i modellen finns två olika mekanismer som kan ge upphov till negativ differentiell konduktivitet. Dels kan elektronerna fastna i fällor, återvändsgränder i systemet, som är sådana att det är svårare att ta sig ur dem då elfältet är stort. Då kan elektronernas medelhastighet och därmed strömmen i materialet minska med ökande elfält. Elektrisk växelverkan mellan elektronerna kan också leda till samma beteende, genom en så kallad coulombblockad. En coulombblockad kan uppstå om antalet ledningselektroner i materialet ökar med ökande spänning. Elektronerna repellerar varandra och ett större antal elektroner kan leda till att transporten blir långsammare, d.v.s. att strömmen minskar.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Lectio praecursoria Tampereen yliopistossa 17.8.2010.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Tämän diplomityön tavoitteena oli suunnitella miehistönkuljetusajoneuvon runko. Rungosta suunniteltiin mahdollisimman hyvin energiaa absorboiva. Rakenne toteutettiin kennora-kenteena. Suunnittelussa sovellettiin koneensuunnittelun periaatteiden lisäksi energiaa ab-sorboivien rakenteiden suunnittelun periaatteita. Myös valmistustekniset näkökohdat otet-tiin huomioon. Rakenteessa hyödynnettiin Ruukki Oy:n Ramor 500 suojausterästä sekä OPTIM 500 MC terästä. Lisäksi erilaisten täyteaineiden käyttöä tutkittiin. Suunnittelun työkaluna käytettiin epälineaarista elementtimenetelmää, koska energiaa ab-sorboivien rakenteiden suunnittelussa on otettava huomioon materiaalien epälineaarinen käyttäytyminen. Rakenteen suunnittelu jakaantui viiteen vaiheeseen. Aluksi rakenteeseen kohdistuvat kuormitukset laskettiin elementtimenetelmän avulla. Esisuunnittelussa lasket-tiin plastisuusteorian avulla alustavasti tarvittavat materiaalipaksuudet. Tämän jälkeen ra-kenteen ydingeometria optimoitiin mahdollisimman hyvin energiaa absorboivaksi. Opti-moinnissa hyödynnettiin elementtimenetelmää. Seuraavassa vaiheessa varmistettiin raken-teen globaalit ominaisuudet. Lopuksi rakenteen kestävyyttä tarkasteltiin elementtimene-telmällä. Runko ei mallien mukaan kestänyt siltä vaadittuja kuormitustapauksia. Mallin kaikki ole-tukset pidettiin varmalla puolella. Reunaehdot oletettiin todellisuutta jäykemmiksi. Myös-kään materiaalin venymänopeudesta johtuvaa lujittumista ei otettu huomioon. Koska mii-naräjähdys on monimutkainen tapahtuma, rungon todellinen kestävyys joudutaan ar-viomaan räjähdystesteillä. Elementtimallien perusteella voidaan kuitenkin sanoa, että ener-giaa absorboiva ajoneuvon runko on mahdollista toteuttaa kennorakenteena. Lisäksi voi-daan todeta, että elementtimenetelmää sopii työvälineeksi tämän tyyppisten rakenteiden suunnitteluun.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Työn tavoitteena oli luoda työkalu kestomagneettikoneiden roottoreiden väsymisen analysointia varten. Työkalu toteutettiin siten, että siihen voidaan liittää oikeasta koneesta mitattu kuormitusdata, sekä tarvittavat materiaalitiedot. Kuormitusdata muunnetaan työkalussa jännityshistoriaksi käyttämällä elementtimenetelmän avulla laskettavaa skaalauskerrointa. Kestoiän laskemiseen analyysityökalu käyttää jännitykseen perustuvaa menetelmää sekä rainflowmenetelmää ja Palmgren-Minerin kumulatiivista vauriosääntöä. Lisäksi työkalu tekee tutkittavalle tapaukselle Smithin väsymislujuuspiirroksen. Edellä mainittujen menetelmien lisäksi työn teoriaosassa esiteltiin väsymisanalyysimenetelmistä myös paikalliseen venymään perustuva menetelmä sekä murtumismekaniikka. Nämä menetelmät jäivät monimutkaisuutensa vuoksi toteuttamatta työkalussa. Väsymisanalyysityökalulla laskettiin kestoiät kahdelle esimerkkitapaukselle. Kummassakin tapauksessa saatiin tulokseksi ääretön kestoikä, mutta aksiaalivuokoneen roottorin dynaaminen varmuus oli pieni. Vaikka tulokset vaikuttavat järkeviltä, ne olisi vielä hyvä verifioida esimerkiksi kaupallisen ohjelmiston avulla täyden varmuuden saamiseksi.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The problem of software (SW) defaults is becoming more and more topical because of increasing amount of the SW and its complication. The majority of these defaults are founded during the test part that consumes about 40-50% of the development efforts. Test automation allows reducing the cost of this process and increasing testing effectiveness. In the middle of 1980 the first tools for automated testing appeared and the automated process was implemented in different kinds of SW testing. In short time, it became obviously, automated testing can cause many problems such as increasing product cost, decreasing reliability and even project fail. This thesis describes automated testing process, its concept, lists main problems, and gives an algorithm for automated test tools selection. Also this work presents an overview of the main automated test tools for embedded systems.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The purpose of this work was evaluating the energetic demand of a seeder-fertilizer machine as a function of the type and handling of vegetal covering culture and of the fertilizer deposition shank depth. A Valtra BM100 tractor was used implemented to pull a high precision seeder-fertilizer machine with four ranks of seeding, spaced 0.9 m for maize culture. Experiment was conducted with design in randomized blocks in factorial plots, in the Laboratory of Machines and Agricultural Mechanization experimental area (LAMMA) of UNESP-Jaboticabal, using two covering cultures (black-mucuna and crotalaria), three handlings of this covering, two mechanical (straw crusher and roller knife) and one chemical (pulverization of herbicide), performed 120 days after seeding of covering cultures and three depths of fertilizer deposition shank, completing 18 treatments, with four repetitions, totaling 72 observations. Parameters of displacement speed, gliding, force on traction bar, peak force, power on pulling bar and fuel consumption were evaluated. It was possible to conclude that force on traction bar was less for depths of 0.11 and 0.14 m of fertilizer plough shank, the same occurring for peak force, power on traction bar and volumetric consumption. The specific consumption was lower at a depth of 0.17 m of fertilizer plough shank. Covering cultures and their handlings did not interfere in the performance of machines under inquiry.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The application of the Extreme Value Theory (EVT) to model the probability of occurrence of extreme low Standardized Precipitation Index (SPI) values leads to an increase of the knowledge related to the occurrence of extreme dry months. This sort of analysis can be carried out by means of two approaches: the block maxima (BM; associated with the General Extreme Value distribution) and the peaks-over-threshold (POT; associated with the Generalized Pareto distribution). Each of these procedures has its own advantages and drawbacks. Thus, the main goal of this study is to compare the performance of BM and POT in characterizing the probability of occurrence of extreme dry SPI values obtained from the weather station of Ribeirão Preto-SP (1937-2012). According to the goodness-of-fit tests, both BM and POT can be used to assess the probability of occurrence of the aforementioned extreme dry SPI monthly values. However, the scalar measures of accuracy and the return level plots indicate that POT provides the best fit distribution. The study also indicated that the uncertainties in the parameters estimates of a probabilistic model should be taken into account when the probability associated with a severe/extreme dry event is under analysis.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

For number of reasons social responsibility in corporations has become a more essential part of business operations than before. Corporate social responsibility (CSR) is dealt with different means and aspects but the overall effects it has on organisations performance, communication and underline actions is indisputable. The thesis describes corporate social responsibility and the main objective was to observe how corporate social responsibility has developed in our case company with answering to main research question how CSR reporting has evolved in UPM-Kymmene Oyj? In addition following questions were also addressed: Is there a monetary value of CSR? What does proficient CSR report consist of? What does corporate social responsibility consist of? Qualitative research method, content analysis to be precise, was chosen and excessive literature study performed to find the theoretical back ground to perform the empirical part of the study. Data for the empirical part was collected from UPM-Kymmene Oyj financial data and annual reports. The study shows that UPM-Kymmene Oyj engagement to CSR and reporting of CSR matter have improved due time but still few managerial implications could be found. UPM-Kymmene Oyj economic key figures are only building shareholder value and stakeholders are identified in very general level. Also CSR data is scattered all over the annual report which causes problems to readers. The scientific importance of this thesis arises from the profound way CSR has been addressed in a holistic manner. Thus it is giving a good basis to understand the underlying reasons of CSR from society towards the organisation and vice versa.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

This bachelor’s thesis is a part of the research project realized in the summer 2011 in Lappeenranta University of Technology. The goal of the project was to develop an automation concept for controlling the externally excited synchronous motor. Thesis concentrates on the testing planning and testing the system. Testing plan was made for three sectors: For the PLC program testing, for the communication testing and for the whole system testing. PLC program was tested with white box and destructive methods. Communication testing was done by switching maximum com-munication speed and checked if communication was reliable. Whole system testing included among other things speed and torque controlling. The system was tested with exploratory testing also. This enabled more reliable and broader testing than with systematical testing only.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

After decades of mergers and acquisitions and successive technology trends such as CRM, ERP and DW, the data in enterprise systems is scattered and inconsistent. Global organizations face the challenge of addressing local uses of shared business entities, such as customer and material, and at the same time have a consistent, unique, and consolidate view of financial indicators. In addition, current enterprise systems do not accommodate the pace of organizational changes and immense efforts are required to maintain data. When it comes to systems integration, ERPs are considered “closed” and expensive. Data structures are complex and the “out-of-the-box” integration options offered are not based on industry standards. Therefore expensive and time-consuming projects are undertaken in order to have required data flowing according to business processes needs. Master Data Management (MDM) emerges as one discipline focused on ensuring long-term data consistency. Presented as a technology-enabled business discipline, it emphasizes business process and governance to model and maintain the data related to key business entities. There are immense technical and organizational challenges to accomplish the “single version of the truth” MDM mantra. Adding one central repository of master data might prove unfeasible in a few scenarios, thus an incremental approach is recommended, starting from areas most critically affected by data issues. This research aims at understanding the current literature on MDM and contrasting it with views from professionals. The data collected from interviews revealed details on the complexities of data structures and data management practices in global organizations, reinforcing the call for more in-depth research on organizational aspects of MDM. The most difficult piece of master data to manage is the “local” part, the attributes related to the sourcing and storing of materials in one particular warehouse in The Netherlands or a complex set of pricing rules for a subsidiary of a customer in Brazil. From a practical perspective, this research evaluates one MDM solution under development at a Finnish IT solution-provider. By means of applying an existing assessment method, the research attempts at providing the company with one possible tool to evaluate its product from a vendor-agnostics perspective.

Relevância:

20.00% 20.00%

Publicador: