Development of military technology and its impact on the Finnish land warfare doctrine

Finnish Defence Studies is published under the auspices of the War College, and the contributions reflect the fields of research and teaching of the College. Finnish Defence Studies will occasionally feature documentation on Finnish Security Policy. Views expressed are those of the authors and do not necessarily imply endorsement by the War College.

Future operational-tactical level warfare : challenges and opportunities for the defence of Finland

Finnish Defence Studies is published under the auspices of the National Defence College, and the contributions reflect the fields of research and teaching of the College. Finnish Defence Studies will occasionally feature documentation on Finnish Security Policy. Views expressed are those of the authors and do not necessarily imply endorsement by the National Defence College.

Effect of loading type on the fatigue strength of symmetric and asymmetric welded joints made of ultra high strength steel

In this study, finite element analyses and experimental tests are carried out in order to investigate the effect of loading type and symmetry on the fatigue strength of three different non-load carrying welded joints. The current codes and recommendations do not give explicit instructions how to consider degree of bending in loading and the effect of symmetry in the fatigue assessment of welded joints. The fatigue assessment is done by using effective notch stress method and linear elastic fracture mechanics. Transverse attachment and cover plate joints are analyzed by using 2D plane strain element models in FEMAP/NxNastran and Franc2D software and longitudinal gusset case is analyzed by using solid element models in Abaqus and Abaqus/XFEM software. By means of the evaluated effective notch stress range and stress intensity factor range, the nominal fatigue strength is assessed. Experimental tests consist of the fatigue tests of transverse attachment joints with total amount of 12 specimens. In the tests, the effect of both loading type and symmetry on the fatigue strength is studied. Finite element analyses showed that the fatigue strength of asymmetric joint is higher in tensile loading and the fatigue strength of symmetric joint is higher in bending loading in terms of nominal and hot spot stress methods. Linear elastic fracture mechanics indicated that bending reduces stress intensity factors when the crack size is relatively large since the normal stress decreases at the crack tip due to the stress gradient. Under tensile loading, experimental tests corresponded with finite element analyzes. Still, the fatigue tested joints subjected to bending showed the bending increased the fatigue strength of non-load carrying welded joints and the fatigue test results did not fully agree with the fatigue assessment. According to the results, it can be concluded that in tensile loading, the symmetry of joint distinctly affects on the fatigue strength. The fatigue life assessment of bending loaded joints is challenging since it depends on whether the crack initiation or propagation is predominant.

Sodankäyntiä lähikirjastojen ympärillä : retorinen analyysi Helsingin Sanomien vuoden 2002 kirjastokeskustelusta

Summary: Warfare around public libraries : a rhetorical analysis of the articles concerning libraries published in Helsingin Sanomat in 2002

Systeemihinnan volatiliteetin mallinus Nord Pool -sähkömarkkinoilla

Työssä tarkastellaan, miten Nord Poolin spot-sähkömarkkinoiden systeemihinnan volatiliteetti on kehittynyt kyseisten markkinoiden kehittyessä ja onko volatiliteetin dynamiikkaa mahdollista mallintaa. Systeemihinta toimii referenssihintana sekä itse sähköpörssissä että pörssin ulkopuolella tapahtuvassa johdannaiskaupankäynnissä. Teoriaosassa luodaan katsaus Nord Pool -markkinoiden toimintaan ja systeemihinnan muodostumisen periaatteisiin. Lisäksi tutustutaan sähkön hinta-aikasarjoille tyypillisiin piirteisiin. Volatiliteetin mallinnus tapahtuu autoregressiivistä konditionaalista heteroskedastista (ARCH) mallia sekä sen laajennuksia hyödyntäen. Työn johtopäätöksinä todetaan, että sähkömarkkinoiden volatiliteettia mallinnettaessa tulisi ottaa huomioon hinnan muutosten asymmetrinen vaikutus volatiliteettiin ja volatiliteetin kausittainen vaihtelu. Lisäksi todettiin, etteivätparametrien kertoimet ole vakioita pitkällä aikavälillä tarkasteltaessa volatiliteetin ARCH-mallinnuksessa.

Torque vibration model of axial-flux surface-mounted permanent magnet synchronous machine

In order that the radius and thus ununiform structure of the teeth and otherelectrical and magnetic parts of the machine may be taken into consideration the calculation of an axial flux permanent magnet machine is, conventionally, doneby means of 3D FEM-methods. This calculation procedure, however, requires a lotof time and computer recourses. This study proves that also analytical methods can be applied to perform the calculation successfully. The procedure of the analytical calculation can be summarized into following steps: first the magnet is divided into slices, which makes the calculation for each section individually, and then the parts are submitted to calculation of the final results. It is obvious that using this method can save a lot of designing and calculating time. Thecalculation program is designed to model the magnetic and electrical circuits of surface mounted axial flux permanent magnet synchronous machines in such a way, that it takes into account possible magnetic saturation of the iron parts. Theresult of the calculation is the torque of the motor including the vibrations. The motor geometry and the materials and either the torque or pole angle are defined and the motor can be fed with an arbitrary shape and amplitude of three-phase currents. There are no limits for the size and number of the pole pairs nor for many other factors. The calculation steps and the number of different sections of the magnet are selectable, but the calculation time is strongly depending on this. The results are compared to the measurements of real prototypes. The permanent magnet creates part of the flux in the magnetic circuit. The form and amplitude of the flux density in the air-gap depends on the geometry and material of the magnetic circuit, on the length of the air-gap and remanence flux density of the magnet. Slotting is taken into account by using the Carter factor in the slot opening area. The calculation is simple and fast if the shape of the magnetis a square and has no skew in relation to the stator slots. With a more complicated magnet shape the calculation has to be done in several sections. It is clear that according to the increasing number of sections also the result will become more accurate. In a radial flux motor all sections of the magnets create force with a same radius. In the case of an axial flux motor, each radial section creates force with a different radius and the torque is the sum of these. The magnetic circuit of the motor, consisting of the stator iron, rotor iron, air-gap, magnet and the slot, is modelled with a reluctance net, which considers the saturation of the iron. This means, that several iterations, in which the permeability is updated, has to be done in order to get final results. The motor torque is calculated using the instantaneous linkage flux and stator currents. Flux linkage is called the part of the flux that is created by the permanent magnets and the stator currents passing through the coils in stator teeth. The angle between this flux and the phase currents define the torque created by the magnetic circuit. Due to the winding structure of the stator and in order to limit the leakage flux the slot openings of the stator are normally not made of ferromagnetic material even though, in some cases, semimagnetic slot wedges are used. In the slot opening faces the flux enters the iron almost normally (tangentially with respect to the rotor flux) creating tangential forces in the rotor. This phenomenon iscalled cogging. The flux in the slot opening area on the different sides of theopening and in the different slot openings is not equal and so these forces do not compensate each other. In the calculation it is assumed that the flux entering the left side of the opening is the component left from the geometrical centre of the slot. This torque component together with the torque component calculated using the Lorenz force make the total torque of the motor. It is easy to assume that when all the magnet edges, where the derivative component of the magnet flux density is at its highest, enter the slot openings at the same time, this will have as a result a considerable cogging torque. To reduce the cogging torquethe magnet edges can be shaped so that they are not parallel to the stator slots, which is the common way to solve the problem. In doing so, the edge may be spread along the whole slot pitch and thus also the high derivative component willbe spread to occur equally along the rotation. Besides forming the magnets theymay also be placed somewhat asymmetric on the rotor surface. The asymmetric distribution can be made in many different ways. All the magnets may have a different deflection of the symmetrical centre point or they can be for example shiftedin pairs. There are some factors that limit the deflection. The first is that the magnets cannot overlap. The magnet shape and the relative width compared to the pole define the deflection in this case. The other factor is that a shifting of the poles limits the maximum torque of the motor. If the edges of adjacent magnets are very close to each other the leakage flux from one pole to the other increases reducing thus the air-gap magnetization. The asymmetric model needs some assumptions and simplifications in order to limit the size of the model and calculation time. The reluctance net is made for symmetric distribution. If the magnets are distributed asymmetrically the flux in the different pole pairs will not be exactly the same. Therefore, the assumption that the flux flows from the edges of the model to the next pole pairs, in the calculation model from one edgeto the other, is not correct. If it were wished for that this fact should be considered in multi-pole pair machines, this would mean that all the poles, in other words the whole machine, should be modelled in reluctance net. The error resulting from this wrong assumption is, nevertheless, irrelevant.

Henkilökohtaisen päätelaitteen käyttö lähimaksujärjestelmässä

Henkilökohtaista luotettavaa päätelaitetta voidaan käyttää maksuvälineenä langattomissa maksujärjestelmissä. Päätelaitteen luotettavuus saadaan aikaan sen sisältämien tietojen salauksen ja käyttäjän tunnistuksen avulla. Kaupankäynnin tietoturvan kannalta järjestelmien tärkeimpiä tehtäviä ovat osapuolten tunnistaminen ja tietoyhteyden suojaaminen. Tässä työssä esitellään automaatti- ja ruokalamaksamisen järjestelmä, jossa käytetään maksuvälineenä Bluetooth-ominaisuudella varustettua kämmentietokonetta. Henkilökohtaisen luotettavan päätelaitteen vaatimuksia ja uhkia käydään läpi. Samoin erilaisia menetelmiä käyttäjän ja laitteiden tunnistukseen sekä tietoyhteyden suojaamiseen. Käyttäjän tunnistus perustuu julkisten avainten varmenteisiin, joihin on sisällytetty tietoa niin asiakkaasta, maksuvälineestä kuin maksumenetelmästäkin. Maksumenetelmäksi on valittu tilien käyttö. Tietoyhteyden suojaamiseen käytetään epäsymmetristä salausta.

Market linkages and volatility spillover: evidence from BRIC countries

The aim of this study is to investigate volatility spillover-effect and market integration between BRIC countries. Motivated by existing literature of market integration between developed and emerging markets, we will investigate market linkages using multivariate asymmetric GARCH BEKK model. The increasing globalization of the financial markets and consequent higher volatility transfer between markets makes it more important to understand market integration between BRIC countries. We investigate the stock market integration and volatility transfer between the BRIC countries form 1998 to 2007, using daily data. The empirical results show that there are international diversification benefits among Brazil, Russia, China and India. U.S. influence to these countries has been week, even though U.S. economy has been leading the global financial markets. From Finnish point of view, diversification benefits are robust but we find some correlation with Russia and China.

Time-varying Risk Premiums and Conditional Market Risk: Empirical Evidence from European Stock Markets

This study investigates the relationship between the time-varying risk premiums and conditional market risk in the stock markets of the ten member countries of Economy and Monetary Union. Second, it examines whether the conditional second moments change over time and are there asymmetric effects in the conditional covariance matrix. Third, it analyzes the possible effects of the chosen testing framework. Empirical analysis is conducted using asymmetric univariate and multivariate GARCH-in-mean models and assuming three different degrees of market integration. For a daily sample period from 1999 to 2007, the study shows that the time-varying market risk alone is not enough to explain the dynamics of risk premiums and indications are found that the market risk is detected only when its price is allowed to change over time. Also asymmetric effects in the conditional covariance matrix, which is found to be time-varying, are clearly present and should be recognized in empirical asset pricing analyses.

Exits - Pääomasijoittajan irtautumisvaihtoehtojen juridista tarkastelua

Pääomasijoittaminen on Suomessa verrattain uusi ilmiö. Tutkielman tarkoitus on ollut tarkastella pääomasijoittajan irtautumista kohdeyhtiöstä juridisesta näkökulmasta. Tutkielman ydin on ollut selvittää pääomasijoittamisen toimijoiden roolien ja niistä johtuvien intressien ristiriitojen vaikutusta irtautumiseen sekä sitä, miten intressiristiriitoja vähennetään erityisesti pääomasijoittajan näkökulmasta. Teoreettisena viitekehyksenä on käytetty päämies-agenttiteoriaa sekä teoriaa asymmetrisestä tiedosta ja moraalisesta uhkapelistä. Toisena tutkimusongelmana on selvitetty pääomasijoittamisen sijoittumista eri oikeudenalojen yhtymäkohtaan sekä luotu katsaus yleisesti pääomasijoittamista koskevaan lainsäädäntöön. Keskeisenä tavoitteena on ollut selvittää, aiheuttaako amerikkalaiseen sopimusmalliin perustuva sopimuskäytäntö ongelmia suomalaisessa juridisessa ympäristössä. Tutkimus on oikeustaloustieteellinen ja tutkimuskohteeseen on tutustuttu alan koti- ja ulkomaisen tutkimuksen ja kirjallisuuden lisäksi teemahaastatteluin. Tutkielman loppupäätelmä on, että pääomasijoittajan irtautumisen turvaamiseksi käytetään juridisesti tehokkaita menetelmiä, joista osakassopimuksen ehdot ovat ennemminkin ennaltaehkäiseviä kuin korjaavia. Intressiristiriitaa vähentämään käytetään myös kannustinjärjestelmä (osakeomistusta, optio-oikeuksia). Tutkimuksessa ei havaittu merkittäviä ongelmia amerikkalaisen sopimusmallin soveltamisessa suomalaiseen käytäntöön.

Krigsväsen

Litteratur om krigsväsen från och med år 2000 vid hela akademibiblioteket fås vid sökning med sökfunktionen Ämnesord och söktermerna krigshistoria, sotahistoria och warfare.