11 resultados para nth characteristic of a real number
em Doria (National Library of Finland DSpace Services) - National Library of Finland, Finland
Resumo:
Tutkimuksen päämääränä oli tutkia miten reaalioptiomenetelmä soveltuu metsäteollisuuden strategisten informaatioteknologiainvestointien arvioimiseen. Tässä tutkimuksessa muodostettiin mukautettu reaalioptiosovelluskehys, esiteltyjen reaalioptiosovelluskehyksien perusteella. Valitut investointiehdotukset arvioitiin muodostetun sovelluskehyksen avulla. Tutkimus oli luonteeltaan kvalitatiivinen. Pääasiallisia tiedonlähteitä olivat lehtiartikkelit, GDSS -istunnot ja haastattelut. Tutkimuksen tuloksena selvisi, että reaalioptiomenetelmä sopii metsäteollisuudenstrategisten informaatioteknologiainvestointien arvioimiseen. On kuitenkin huomioitava, että investoinnin suunnitteluprosessin kypsyysaste vaikuttaa reaalioptiomenetelmän soveltamiseen. Tutkimuksessa arvioidut investoinnit ovat investoinnin suunnitteluvaiheen varhaisessa vaiheessa.
Resumo:
The thesis examines the profitability of DMAC trading rules in the Finnish stock market over the 1996-2012 period. It contributes to the existing technical analysis literature by comparing for the first time the performance of DMAC strategies based on individual stock trading portfolios to the performance of index trading strategies based on the trading on the index (OMX Helsinki 25) that consists of the same stocks. Besides, the market frictions including transaction costs and taxes are taken into account, and the results are reported from both institutional and individual investor’s perspective. Performance characteristic of DMAC rules are evaluated by simulating 19,900 different trading strategies in total for two non- overlapping 8-year sub-periods, and decomposing the full-sample-period performance of DMAC trading strategies into distinct bullish- and bearish-period performances. The results show that the best DMAC rules have predictive power on future price trends, and these rules are able to outperform buy-and-hold strategy. Although the performance of the DMAC strategies is highly dependent on the combination of moving average lengths, the best DMAC rules of the first sub-period have also performed well during the latter sub-period in the case of individual stock trading strategies. According to the results, the outperformance of DMAC trading rules over buy-and-hold strategy is mostly attributed to their superiority during the bearish periods, and particularly, during stock market crashes.
Resumo:
Real option valuation, in particular the fuzzy pay-off method, has proven to be useful in defining risk and visualizing imprecision of investments in various industry applications. This study examines whether the evaluation of risk and profitability for public real estate investments can be improved by using real option methodology. Firstly, the context of real option valuation in the real estate industry is examined. Further, an empirical case study is performed on 30 real estate investments of a Finnish government enterprise in order to determine whether the presently used investment analysis system can be complemented by the pay-off method. Despite challenges in the application of the pay-off method to the case company’s large investment base, real option valuation is found to create additional value and facilitate more robust risk analysis in public real estate applications.
The effects of real time control of welding parameters on weld quality in plasma arc keyhole welding
Resumo:
Joints intended for welding frequently show variations in geometry and position, for which it is unfortunately not possible to apply a single set of operating parameters to ensure constant quality. The cause of this difficulty lies in a number of factors, including inaccurate joint preparation and joint fit up, tack welds, as well as thermal distortion of the workpiece. In plasma arc keyhole welding of butt joints, deviations in the gap width may cause weld defects such as an incomplete weld bead, excessive penetration and burn through. Manual adjustment of welding parameters to compensate for variations in the gap width is very difficult, and unsatisfactory weld quality is often obtained. In this study a control system for plasma arc keyhole welding has been developed and used to study the effects of the real time control of welding parameters on gap tolerance during welding of austenitic stainless steel AISI 304L. The welding tests demonstrated the beneficial effect of real time control on weld quality. Compared with welding using constant parameters, the maximum tolerable gap width with an acceptable weld quality was 47% higher when using the real time controlled parameters for a plate thickness of 5 mm. In addition, burn through occurred with significantly larger gap widths when parameters were controlled in real time. Increased gap tolerance enables joints to be prepared and fit up less accurately, saving time and preparation costs for welding. In addition to the control system, a novel technique for back face monitoring is described in this study. The test results showed that the technique could be successfully applied for penetration monitoring when welding non magnetic materials. The results also imply that it is possible to measure the dimensions of the plasma efflux or weld root, and use this information in a feedback control system and, thus, maintain the required weld quality.
Resumo:
This dissertation describes an approach for developing a real-time simulation for working mobile vehicles based on multibody modeling. The use of multibody modeling allows comprehensive description of the constrained motion of the mechanical systems involved and permits real-time solving of the equations of motion. By carefully selecting the multibody formulation method to be used, it is possible to increase the accuracy of the multibody model while at the same time solving equations of motion in real-time. In this study, a multibody procedure based on semi-recursive and augmented Lagrangian methods for real-time dynamic simulation application is studied in detail. In the semirecursive approach, a velocity transformation matrix is introduced to describe the dependent coordinates into relative (joint) coordinates, which reduces the size of the generalized coordinates. The augmented Lagrangian method is based on usage of global coordinates and, in that method, constraints are accounted using an iterative process. A multibody system can be modelled as either rigid or flexible bodies. When using flexible bodies, the system can be described using a floating frame of reference formulation. In this method, the deformation mode needed can be obtained from the finite element model. As the finite element model typically involves large number of degrees of freedom, reduced number of deformation modes can be obtained by employing model order reduction method such as Guyan reduction, Craig-Bampton method and Krylov subspace as shown in this study The constrained motion of the working mobile vehicles is actuated by the force from the hydraulic actuator. In this study, the hydraulic system is modeled using lumped fluid theory, in which the hydraulic circuit is divided into volumes. In this approach, the pressure wave propagation in the hoses and pipes is neglected. The contact modeling is divided into two stages: contact detection and contact response. Contact detection determines when and where the contact occurs, and contact response provides the force acting at the collision point. The friction between tire and ground is modelled using the LuGre friction model, which describes the frictional force between two surfaces. Typically, the equations of motion are solved in the full matrices format, where the sparsity of the matrices is not considered. Increasing the number of bodies and constraint equations leads to the system matrices becoming large and sparse in structure. To increase the computational efficiency, a technique for solution of sparse matrices is proposed in this dissertation and its implementation demonstrated. To assess the computing efficiency, augmented Lagrangian and semi-recursive methods are implemented employing a sparse matrix technique. From the numerical example, the results show that the proposed approach is applicable and produced appropriate results within the real-time period.
Resumo:
Laajojen pintojen kuvaaminen rajoitetussa työskentelytilassa riittävällä kuvatarkkuudella voi olla vaikeaa. Kuvaaminen on suoritettava osissa ja osat koottava saumattomaksi kokonaisnäkymäksi eli mosaiikkikuvaksi. Kuvauslaitetta käsin siirtelevän käyttäjän on saatava välitöntä palautetta, jotta mosaiikkiin ei jäisi aukkoja ja työ olisi nopeaa. Työn tarkoituksena oli rakentaa pieni, kannettava ja tarkka kuvauslaite paperi- ja painoteollisuuden tarpeisiin sekä kehittää palautteen antamiseen menetelmä, joka koostaaja esittää karkeaa mosaiikkikuvaa tosiajassa. Työssä rakennettiin kaksi kuvauslaitetta: ensimmäinen kuluttajille ja toinen teollisuuteen tarkoitetuista osista. Kuvamateriaali käsiteltiin tavallisella pöytätietokoneella. Videokuvien välinen liike laskettiin yksinkertaisella seurantamenetelmällä ja mosaiikkikuvaa koottiin kameroiden kuvanopeudella. Laskennallista valaistuksenkorjausta tutkittiin ja kehitetty menetelmä otettiin käyttöön. Ensimmäisessä kuvauslaitteessa on ongelmia valaistuksen ja linssivääristymien kanssa tuottaen huonolaatuisia mosaiikkikuvia. Toisessa kuvauslaitteessa nämä ongelmat on korjattu. Seurantamenetelmä toimii hyvin ottaen huomioon sen yksinkertaisuuden ja siihen ehdotetaan monia parannuksia. Työn tulokset osoittavat, että tosiaikainen mosaiikkikuvan koostaminen megapikselin kuvamateriaalista on mahdollista kuluttajille tarkoitetulla tietokonelaitteistolla.
Resumo:
By an exponential sum of the Fourier coefficients of a holomorphic cusp form we mean the sum which is formed by first taking the Fourier series of the said form,then cutting the beginning and the tail away and considering the remaining sum on the real axis. For simplicity’s sake, typically the coefficients are normalized. However, this isn’t so important as the normalization can be done and removed simply by using partial summation. We improve the approximate functional equation for the exponential sums of the Fourier coefficients of the holomorphic cusp forms by giving an explicit upper bound for the error term appearing in the equation. The approximate functional equation is originally due to Jutila [9] and a crucial tool for transforming sums into shorter sums. This transformation changes the point of the real axis on which the sum is to be considered. We also improve known upper bounds for the size estimates of the exponential sums. For very short sums we do not obtain any better estimates than the very easy estimate obtained by multiplying the upper bound estimate for a Fourier coefficient (they are bounded by the divisor function as Deligne [2] showed) by the number of coefficients. This estimate is extremely rough as no possible cancellation is taken into account. However, with small sums, it is unclear whether there happens any remarkable amounts of cancellation.
Resumo:
This thesis describes the process of the integration of a real-time simulator environment with a motion platform and a haptic device as a part of the Kvalive project. Several programs running on two computers were made to control the different devices of the environment. User tests were made to obtain information of needed improvements to make the simulator more realistic. Also new ideas for improving the simulator and directions of further research were obtained with the help of this research.
Resumo:
This thesis introduces a real-time simulation environment based on the multibody simulation approach. The environment consists of components that are used in conventional product development, including computer aided drawing, visualization, dynamic simulation and finite element software architecture, data transfer and haptics. These components are combined to perform as a coupled system on one platform. The environment is used to simulate mobile and industrial machines at different stages of a product life time. Consequently, the demands of the simulated scenarios vary. In this thesis, a real-time simulation environment based on the multibody approach is used to study a reel mechanism of a paper machine and a gantry crane. These case systems are used to demonstrate the usability of the real-time simulation environment for fault detection purposes and in the context of a training simulator. In order to describe the dynamical performance of a mobile or industrial machine, the nonlinear equations of motion must be defined. In this thesis, the dynamical behaviour of machines is modelled using the multibody simulation approach. A multibody system may consist of rigid and flexible bodies which are joined using kinematic joint constraints while force components are used to describe the actuators. The strength of multibody dynamics relies upon its ability to describe nonlinearities arising from wearing of the components, friction, large rotations or contact forces in a systematic manner. For this reason, the interfaces between subsystems such as mechanics, hydraulics and control systems of the mechatronic machine can be defined and analyzed in a straightforward manner.
Resumo:
This Master's thesis studies the development of interaction and socialization in online communities. A large number of online communities fade away even before they really get started. In many occasions the reason is that the community does not give anything new, or even if they do, the delivery does not satisfy the users. In this thesis guidelines were developed to help to see important things, which might be forgotten when developing an online community. The thesis goes through the characteristic of an online community and human behaviour related to them and also compares behaviour in the Internet and real life. In addition, usability is an important part of the online communities and thus it is also covered in this thesis. As a result of this thesis an 8-step guideline was developed to ease the design of an online community. Guidelines were also applied to two real life cases which are described as one part of this work.
Resumo:
Spermatogenesis is a unique process compared to cell differentiation in somatic tissues. Germ cells undergo a considerable number of metabolic and morphological changes during their differentiation: they initially proliferate by mitosis to increase in number; at some point they scramble their genetic material by meiosis, to create new genetic combinations that are the basis for evolution through natural selection and, finally, they change their shape and produce specialized structures characteristic of the mature sperm. Germ cells display an astonishingly broad transcription of their genome compared to differentiated somatic cells. Moreover, the different RNAs need to be specifically regulated in space and time for sperm production to occur appropriately. Different proteins localized in specific subcellular compartments, along with regulatory small RNAs, have an essential role in the proper execution of the different steps of spermatogenesis. These ribonucleoprotein granules interact with cytoplasmic vesicles and organelles to accomplish their role during sperm development. In this study, we characterized the most prominent ribonucleoprotein granule found in germ cells, the Chromatoid body (CB). For the first time we investigated the interaction of the CB with the cytoplasmic vesicles that surround it. These studies directed us to the description of Retromer proteins in germ cells and their involvement with the CB and the acrosome formation. Moreover, we discovered the interplay between the CB and the lysosome system in haploid round spermatids, and identified FYCO1, a new protein central to this interaction. Our results suggest that the vesicular transport system participates in the CB-mediated RNA regulation during sperm development.