Testing a large-scale forestry scenario model by means of successive inventories on a forest property

Abstract

Linear prediction application for modelling the relationships between a large number of stand characteristics of Norway spruce stands

Abstract

Analysis of Industrial Granular Flow Applications by Using Advanced Collision Models

Granular flow phenomena are frequently encountered in the design of process and industrial plants in the traditional fields of the chemical, nuclear and oil industries as well as in other activities such as food and materials handling. Multi-phase flow is one important branch of the granular flow. Granular materials have unusual kinds of behavior compared to normal materials, either solids or fluids. Although some of the characteristics are still not well-known yet, one thing is confirmed: the particle-particle interaction plays a key role in the dynamics of granular materials, especially for dense granular materials. At the beginning of this thesis, detailed illustration of developing two models for describing the interaction based on the results of finite-element simulation, dimension analysis and numerical simulation is presented. The first model is used to describing the normal collision of viscoelastic particles. Based on some existent models, more parameters are added to this model, which make the model predict the experimental results more accurately. The second model is used for oblique collision, which include the effects from tangential velocity, angular velocity and surface friction based on Coulomb's law. The theoretical predictions of this model are in agreement with those by finite-element simulation. I n the latter chapters of this thesis, the models are used to predict industrial granular flow and the agreement between the simulations and experiments also shows the validation of the new model. The first case presents the simulation of granular flow passing over a circular obstacle. The simulations successfully predict the existence of a parabolic steady layer and show how the characteristics of the particles, such as coefficients of restitution and surface friction affect the separation results. The second case is a spinning container filled with granular material. Employing the previous models, the simulation could also reproduce experimentally observed phenomena, such as a depression in the center of a high frequency rotation. The third application is about gas-solid mixed flow in a vertically vibrated device. Gas phase motion is added to coherence with the particle motion. The governing equations of the gas phase are solved by using the Large eddy simulation (LES) and particle motion is predicted by using the Lagrangian method. The simulation predicted some pattern formation reported by experiment.

Superjumborullien rullauksen hallinta

UPM-Kymmene Oyj:n Jämsänkosken PK6:n ongelmana ovat olleet ajoittaiset pohjakatkot suurilla rullilla. Diplomityön tavoitteena oli parantaa superjumborullien rullauksen hallintaa Jagenbergin rakentamalla VariTop keskiörullaimella. Kirjallisuusosassa selvitettiin rullanmuodostumista ja erilaisia rullausteorioita. Samalla käytiin läpi paperin rullautuvuuteen vaikuttavia tekijöitä, rullausperäisten vikojen muodostumisen syitä sekä pehmeän rullaussylinterin etuja verrattuna kovaan sylinteriin. Kokeellisessa osassa suoritettiin koeajoja tuotannon pituusleikkurilla. Näistä kokeista saatujen tulosten perusteella leikkurin ajoreseptit päivitettiin vastaamaanoptimaalisinta rullarakennetta. Pehmeän rullaussylinterin etuja verrattuna kovaan rullaussylinteriin selvitettiin koeajoissa Voithin koeleikkurilla Saksan Krefeldissä. Tuloksista selvisi, että samalla ajoreseptillä rullattaessa pehmeä sylinteri antoi valmiille rullalle suuremman kovuuden. Myös paperissa olevien profiilivirheiden vaikutukset lievenivät käytettäessä pehmeää rullaussylinteriä. Istukoiden luistamisesta johtuvaa hylsyjen sisäpinnan jauhautumista on ilmennyt suurilla jumborullilla. Tämä johtuu todennäköisimmin kasvaneesta rasituksesta hylsyn sisäpinnalla, mikä on seurausta rullien kasvusta. Ratkaisuina tälle ongelmalle on mahdollinen istukan pidentäminen sekä välyksen pienentäminen istukan ja hylsyn välissä. Myös hylsyjen toimintaa testattiin rullauksessa jahuomattiin niiden täyttävän toimittajien antamat laatuarvot. Lepo- ja liikekitkalla tiedetään olevan suuri merkitys rullausperäisten vikojenmuodostumiseen. Eri lajeista lähetettiin paperinäytteitä UPM-Kymmene Oyj:n Lappeenrannan tutkimuskeskukseen kitkojen määrittämiseksi. Tulosten perusteella havaittiin luettelolajilla lepo- ja liikekitkassa merkittävä ero. Standardi SC lajilla ero oli selvästi pienempi kuin luettelolajilla. Tämä saattaa olla yksi syy luettelolajeilla ilmeneviin pohjaongelmiin.

Software SMEs asStrategic Partners in the Partner Programs of Large International Companies

Tutkielman tavoitteena oli tutkia pienten- ja keskisuurten (PK) ohjelmistoyritysten kansainvälisiä kumppanuuksia. Päätavoitteena oli löytää keinoja kuinka PK-ohjelmistoyritykset voisivat tulla strategisiksi kumppaneksi suurten kansainvälisten yritysten kumppanuusohjelmissa. Lisäksi tutkielmassa oli tavoitteena selvittää kuinka kumppaneiden välistä sitoutumista voitaisiin vahvistaa, jotta PK-ohjelmistoyritykset voisivat saavuttaa todellista lisäarvoa ja kansainvälistä kasvua kumppanuusohjelmien kautta. Tutkielma jakaantuu teoreettiseen ja empiiriseen osaan. Teoreettinen osa keskittyy tarkastelemaan korkean teknologian markkinointia ohjelmistoalalla sekä kansainvälisiä kumppanuuksia. Suurten yritystenkumppanuusohjelmia ei ole tutkittu suomalaisten PK-ohjelmistoyritysten näkökulmasta, minkä vuoksi empiirinen tutkimus on perusteltua. Empiirinen tutkimus toteutettiin laadullisena case-tutkimuksena ja tutkimusmenetelmänä käytettiin puolistrukturoitua haastattelua. Tutkimustulokset osoittavat, että strategisen kumppanin aseman saavuttaminen on pitkä ja haastava matka PK-yrityksille. Suurten kansainvälisten yritysten kumppanuusohjelmat ovat useimmiten monimutkaisia ja todellisen lisäarvon saavuttaminen kumppanuusohjelman kautta vaatii paljon resursseja PK-yrityksiltä. Jotta PK-yritykset voisivat saavuttaa ja säilyttää strategisen kumppanin aseman kumppanuusohjelmassa, vaatii se aktiivista ja päivittäistä vuorovaikutusta kumppaneiden kesken. Erityisesti tiiviit henkilösuhteet oikeiden avainhenkilöiden kanssa ovat välttämättömyys. Läheiset kontaktit mahdollistavat sen, että PK-yritykset voivat ainakin osittain ohittaa kumppanuusohjelman byrokratian, mikä lisää luottamusta ja sitoutumista kumppanuussuhteessa sekä edistää kansainvälistä kasvua ja menestystä liiketoiminnassa.

A computationally efficient shear deformable beam element for large deformation multibody applications

In this paper, a new two-dimensional shear deformable beam element based on the absolute nodal coordinate formulation is proposed. The nonlinear elastic forces of the beam element are obtained using a continuum mechanics approach without employing a local element coordinate system. In this study, linear polynomials are used to interpolate both the transverse and longitudinal components of the displacement. This is different from other absolute nodal-coordinate-based beam elements where cubic polynomials are used in the longitudinal direction. The accompanying defects of the phenomenon known as shear locking are avoided through the adoption of selective integration within the numerical integration method. The proposed element is verified using several numerical examples, and the results are compared to analytical solutions and the results for an existing shear deformable beam element. It is shown that by using the proposed element, accurate linear and nonlinear static deformations, as well as realistic dynamic behavior, can be achieved with a smaller computational effort than by using existing shear deformable two-dimensional beam elements.

Numerical and ExperimentalModelling of Gas Flow and Heat Transfer in the Air Gap of An Electric Machine

This work deals with the cooling of high-speed electric machines, such as motors and generators, through an air gap. It consists of numerical and experimental modelling of gas flow and heat transfer in an annular channel. Velocity and temperature profiles are modelled in the air gap of a high-speed testmachine. Local and mean heat transfer coefficients and total friction coefficients are attained for a smooth rotor-stator combination at a large velocity range. The aim is to solve the heat transfer numerically and experimentally. The FINFLO software, developed at Helsinki University of Technology, has been used in the flow solution, and the commercial IGG and Field view programs for the grid generation and post processing. The annular channel is discretized as a sector mesh. Calculation is performed with constant mass flow rate on six rotational speeds. The effect of turbulence is calculated using three turbulence models. The friction coefficient and velocity factor are attained via total friction power. The first part of experimental section consists of finding the proper sensors and calibrating them in a straight pipe. After preliminary tests, a RdF-sensor is glued on the walls of stator and rotor surfaces. Telemetry is needed to be able to measure the heat transfer coefficients at the rotor. The mean heat transfer coefficients are measured in a test machine on four cooling air mass flow rates at a wide Couette Reynolds number range. The calculated values concerning the friction and heat transfer coefficients are compared with measured and semi-empirical data. Heat is transferred from the hotter stator and rotor surfaces to the coolerair flow in the air gap, not from the rotor to the stator via the air gap, althought the stator temperature is lower than the rotor temperature. The calculatedfriction coefficients fits well with the semi-empirical equations and precedingmeasurements. On constant mass flow rate the rotor heat transfer coefficient attains a saturation point at a higher rotational speed, while the heat transfer coefficient of the stator grows uniformly. The magnitudes of the heat transfer coefficients are almost constant with different turbulence models. The calibrationof sensors in a straight pipe is only an advisory step in the selection process. Telemetry is tested in the pipe conditions and compared to the same measurements with a plain sensor. The magnitudes of the measured data and the data from the semi-empirical equation are higher for the heat transfer coefficients than thenumerical data considered on the velocity range. Friction and heat transfer coefficients are presented in a large velocity range in the report. The goals are reached acceptably using numerical and experimental research. The next challenge is to achieve results for grooved stator-rotor combinations. The work contains also results for an air gap with a grooved stator with 36 slots. The velocity field by the numerical method does not match in every respect the estimated flow mode. The absence of secondary Taylor vortices is evident when using time averagednumerical simulation.

Competitor Information andCompetitive Knowledge Management in a Large Industrial Organization

Thisthesis supplements the systematic approach to competitive intelligence and competitor analysis by introducing an information-processing perspective on management of the competitive environment and competitors therein. The cognitive questions connected to the intelligence process and also the means that organizational actors use in sharing information are discussed. The ultimate aim has been to deepen knowledge of the different intraorganizational processes that are used in acorporate organization to manage and exploit the vast amount of competitor information that is received from the environment. Competitor information and competitive knowledge management is examined as a process, where organizational actorsidentify and perceive the competitive environment by using cognitive simplification, make interpretations resulting in learning and finally utilize competitor information and competitive knowledge in their work processes. The sharing of competitive information and competitive knowledge is facilitated by intraorganizational networks that evolve as a means of developing a shared, organizational level knowledge structure and ensuring that the right information is in the right place at the right time. This thesis approaches competitor information and competitive knowledge management both theoretically and empirically. Based on the conceptual framework developed by theoretical elaboration, further understanding of the studied phenomena is sought by an empirical study. The empirical research was carried out in a multinationally operating forest industry company. This thesis makes some preliminary suggestions of improving the competitive intelligence process. It is concluded that managing competitor information and competitive knowledge is not simply a question of managing information flow or improving sophistication of competitor analysis, but the crucial question to be solved is rather, how to improve the cognitive capabilities connected to identifying and making interpretations of the competitive environment and how to increase learning. It is claimed that competitive intelligence can not be treated like an organizational function or assigned solely to a specialized intelligence unit.

Dynamic analysis of belt-drives using the absolute nodal coordinate formulation

Belt-drive systems have been and still are the most commonly used power transmission form in various applications of different scale and use. The peculiar features of the dynamics of the belt-drives include highly nonlinear deformation,large rigid body motion, a dynamical contact through a dry friction interface between the belt and pulleys with sticking and slipping zones, cyclic tension of the belt during the operation and creeping of the belt against the pulleys. The life of the belt-drive is critically related on these features, and therefore, amodel which can be used to study the correlations between the initial values and the responses of the belt-drives is a valuable source of information for the development process of the belt-drives. Traditionally, the finite element models of the belt-drives consist of a large number of elements thatmay lead to computational inefficiency. In this research, the beneficial features of the absolute nodal coordinate formulation are utilized in the modeling of the belt-drives in order to fulfill the following requirements for the successful and efficient analysis of the belt-drive systems: the exact modeling of the rigid body inertia during an arbitrary rigid body motion, the consideration of theeffect of the shear deformation, the exact description of the highly nonlinear deformations and a simple and realistic description of the contact. The use of distributed contact forces and high order beam and plate elements based on the absolute nodal coordinate formulation are applied to the modeling of the belt-drives in two- and three-dimensional cases. According to the numerical results, a realistic behavior of the belt-drives can be obtained with a significantly smaller number of elements and degrees of freedom in comparison to the previously published finite element models of belt-drives. The results of theexamples demonstrate the functionality and suitability of the absolute nodal coordinate formulation for the computationally efficient and realistic modeling ofbelt-drives. This study also introduces an approach to avoid the problems related to the use of the continuum mechanics approach in the definition of elastic forces on the absolute nodal coordinate formulation. This approach is applied to a new computationally efficient two-dimensional shear deformable beam element based on the absolute nodal coordinate formulation. The proposed beam element uses a linear displacement field neglecting higher-order terms and a reduced number of nodal coordinates, which leads to fewer degrees of freedom in a finite element.