Positional dependence of material flow in friction stir welding: analysis of joint line remnant and its relevance to dissimilar metal welding

Understanding material flow in friction stir welding is important for production of sound dissimilar metal welding that control the intermixing of two alloys being welded and consequent formation of new constituents which influences the weld properties. In the present experimental investigation material flow patterns are visualised using dissimilar and similar aluminium alloys using a simple innovative ,experiment. The experimental results reveal that only a portion of material transported from the leading edge undergoes chaotic flow and the remaining is deposited systematically in the trailing edge of the weld. Using this information it is shown that the formation of a friction stir welding defect, joint line remnant, does not occur only when the weld interface is on the advancing side. The material flow visualisation study has been utilised to analyse the mechanism of weld formation and its usefulness in improving fatigue properties and for dissimilar metal welds.

Guessing under source uncertainty with side information

We study the problem of guessing the realization of a finite alphabet source, when some side information is provided, in a setting where the only knowledge the guesser has about the source and the correlated side information is that the joint source is one among a family. We define a notion of redundancy, identify a quantity that measures this redundancy, and study its properties. We then identify good guessing strategies that minimize the supremum redundancy (over the family). The minimum value measures the richness of the uncertainty class.

Evolution and decay of cylindrical and spherical nonlinear acoustic waves generated by a sinusoidal source

The present work gives a comprehensive numerical study of the evolution and decay of cylindrical and spherical nonlinear acoustic waves generated by a sinusoidal source. Using pseudospectral and predictor–corrector implicit finite difference methods, we first reproduced the known analytic results of the plane harmonic problem to a high degree of accuracy. The non-planar harmonic problems, for which the amplitude decay is faster than that for the planar case, are then treated. The results are correlated with the known asymptotic results of Scott (1981) and Enflo (1985). The constant in the old-age formula for the cylindrical canonical problem is found to be 1.85 which is rather close to 2, ‘estimated’ analytically by Enflo. The old-age solutions exhibiting strict symmetry about the maximum are recovered; these provide an excellent analytic check on the numerical solutions. The evolution of the waves for different source geometries is depicted graphically.

Narrowband Detection of Acoustic Source in Shallow Ocean using Vector Sensor Array

The problem of narrowband CFAR (constant false alarm rate) detection of an acoustic source at an unknown location in a range-independent shallow ocean is considered. If a target is present, the received signal vector at an array of N sensors belongs to an M-dimensional subspace if N exceeds the number of propagating modes M in the ocean. A subspace detection method which utilises the knowledge of the signal subspace to enhance the detector performance is presented in thisMpaper. It is shown that, for a given number of sensors N, the performance of a detector using a vector sensor array is significantly better than that using a scalar sensor array. If a target is detected, the detector using a vector sensor array also provides a concurrent coarse estimate of the bearing of the target.

A Method for Purifying Bulk Gallium Arsenide by Chemical Vapour Transport

The need for high purity materials for the growth of epitaxial layers of GaAs and the limitations of present source materials are discussed. A for purifying bulk quantitites of GaAs using chemical vapour transport is presented. GaAs is contained in a silica capsule which has a small orifice allow movement of gas between inside and outside. The capsule is contained in a heated tube and hydrogen chloride is used as the transporting agent. Growth rates of 0.1 g/h have been obtained and evidence for the purification is presented along with a discussion of the principles involved. The potentialities of the method for both purification and for the growth of single crystal substrate material are stressed.--AA

Joint Source-Channel Coding over a Fading Multiple Access Channel with Partial Channel State Information

In this paper we address the problem of transmission of correlated sources over a fast fading multiple access channel (MAC) with partial channel state information available at both the encoders and the decoder. We provide sufficient conditions for transmission with given distortions. Next these conditions are specialized to a Gaussian MAC (GMAC). We provide the optimal power allocation strategy and compare the strategy with various levels of channel state information.

Characterization of compact ICP ion source for focused ion beam applications

A compact, high brightness 13.56 MHz inductively coupled plasma ion source without any axial or radial multicusp magnetic fields is designed for the production of a focused ion beam. Argon ion current of density more than 30 mA/cm(2) at 4 kV potential is extracted from this ion source and is characterized by measuring the ion energy spread and brightness. Ion energy spread is measured by a variable-focusing retarding field energy analyzer that minimizes the errors due t divergence of ion beam inside the analyzer. Brightness of the ion beam is determined from the emittance measured by a fully automated and locally developed electrostatic sweep scanner. By optimizing various ion source parameters such as RF power, gas pressure and Faraday shield, ion beams with energy spread of less than 5 eV and brightness of 7100 Am(-2)sr(-1)eV(-1) have been produced. Here, we briefly report the details of the ion source, measurement and optimization of energy spread and brightness of the ion beam. (C) 2010 Elsevier B.V. All rights reserved.

“Empire is a state of mind” – Imagining Eurasia in Russia –

Työssäni tarkastelen venäläistä neo-euraasianistista liikettä ja tapoja joilla liikkeen aktivistit rakentavat Euraasiasta yhtenäistä kokonaisuutta ja imperiumia. Keskeisiä tutkimuskysymyksiäni ovat: Mikä imperiumi on ja mitkä ovat sen keskeisiä motivaatioita ja teemoja? Kuinka imperiumin idea rakentuu tai käsitetään ja tämän voi tulkita? Minkälaisia seurauksia voi tulkita heidän tavallaan Euraasia nähdä olevan? Materiaalina käytän haastatteluja, jotka on kerätty Moskovassa keväällä 2008, ja liikkeen kirjallisia tuotoksia (lehdet ja Internet -sivut). Neo-euraasianistisella liikkeellä tarkoitan tässä työssä Kansainvälistä Euraasianistista liikettä (Meždunarodnoe Evrazijskoe Dviženie) ja sen alahaaraa Euraasianistista Nuorisoliittoa (Evrazijskij Sojuz Molodëži). Liike perustettiin virallisesti 2003, mutta rakentaa vahvasti historiallista yhteyttä 1930 -luvun klassiseen eurasianismiin. Tämän lisäksi sen diskurssissa on paljon neuvostoliittolaisia, fasistisia, uuskonservatiivisia ja nationalistisia piirteitä. Liikkeen johtohahmo on filosofi-geopoliitikko Alexandr Dugin. Työn tausta-ajatuksena minua kiinnostaa etenkin nk. älymystön tai intelligenttien vaikutus nationalismiin tai sosiaalisia ryhmiä määrittelevien diskurssien kehitykseen ja muutokseen.Tarkastelen materiaalia diskurssianalyyttisesta näkökulmasta. Näen diskurssianalyysin sen tutkimisena, miten sosiaalista todellisuutta tuotetaan erilaisissa sosiaalisissa käytännöissä. Samalla näiden diskurssien tutkiminen, foucautlaisen perinteen myötä, tarkastelee kriittisesti niiden tuottamia (aktualisoituneita sekä potentiaalisia) valtasuhteita. Käytän työssäni myös Benedict Andersonin kuvitellun yhteisön (imagined communities) käsitettä, joka auttaa hahmottamaan tapaa, jolla tutkimuskohteeni rakentavat imperiumia yhteisönä. Aktivistien puheessa imperiumi (imperiâ) tulee esiin pääasiallisesti positiivisesti ja ”heidän omanaan,” kun taas termi imperialismi (imperializm) pääosin negatiivisena, liittyen etenkin keskeisenä vihollisena pidettyihin Yhdysvaltoihin. Esiin nousee monta toisiinsa liittyvää teemaa, jotka jaottelen viideksi pääteemaksi. Näistä tarkastelen lähemmin imperiumia ”kaikkien kansojen hyväntekijänä (poliittinen puoli)”, ulkoisen voiman lähteenä (historiallis-geopoliittinen puoli) sekä kollektiivisen subjektin luojana (imperialistis-nationalistinen puoli). Pyrin kontekstualisoimaan diskurssin ja tarkastelemaan tapoja, joilla se ammentaa motiiveja myös historiallis-kulttuurisista tavoista hahmottaa aluetta ja sen asukkaita. Käsittelen myös kansan, kansakunnan, etnoksen ja nationalismin käsitteitä ja sitä, miten ne nousevat neo-eurasianistisessa diskursissa esiin. Imperiaalisen nationalismin (imperskij nacionalizm) käsite auttaa ymmärtämään niitä tapoja, jolla liike tekee sekä pesäeroa nationalismiin että samalla hyödyntää monia nationalistisen diskurssin perusteemoja. Eräs liikkeen diskurssin keskeisistä eroista niin sanottuun nationalismin valtavirtaan on ”kansakunnan (naciâ)” käsitteen vahva negatiivinen konnotaatio. Sen vastakohtana esiin nostetaan vahvasti kansan (narod) käsite. Samalla kuitenkin etnisen venäläisen (russkij) käsitettä käytetään tavallista laajemmin ja kattavammin kuin tavallisesti, ja ennen kaikkea Venäjä nousee imperiumin keskeisimmäksi tekijäksi. Euraasialaiseen imperiumiin liitetyistä positiivistista mielikuvista käsittelen tarkemmin monikansallisuuden ja kansojen kodin ideaa, joka nousee mielestäni huomattavaksi retoriseksi taustaksi kaikessa materiaalissa. Tähän liittyy vahvasti myös saman teeman sivujuonne, eli imperiumin ”vapauttava” rooli. Tulkitsen, että liikkeen imperiumi -diskurssilla on instrumentaalinen luonne: se legitimoi aktivistien vaatimuksia varsinkin entisen Neuvostoliiton alueen suhteen. ”Euraasialaisen kansan” ajatus toimii mahdollisena Euraasiaa yhteisenä tekijänä ”Neuvostokansan” tilalla. Sen taustalla materiaalistani päätellen siintävät kuitenkin enemmänkin Venäjä ja venäläis -spesifit vaateet kuin koko Euraasia. Pohdin myös kansakunnan (nation) hyljeksimisen syitä ja käsitteen sopivuutta Venäjälle, kuten myös venäläisyyden käsitteiden kerrostuneisuutta. Kokonaisuudessaan imperiumi tuli esiin abstraktina, utopistisena ja ”totaalisena” kokonaisuutena.

Köyhyyden perintö : Tutkimus kulttuurisen tiedon sisällöistä ja jatkuvuuksista suomalaisissa elämäkerta- ja sananlaskuaineistoissa

The Legacy of Poverty. A Study of the substance and continuity of cultural knowledge in Finnish biographical and proverbial texts The study focuses on the idea of the cultural knowledge and shared understanding that ordinary people, folk , have of the concepts and ideas about rural based poverty in Finland. Throughout 19th century and well into 20th century, the majority of the population remained agrarian and poor. By the 1950s, most people still lived in rural areas and a majority of them earned their living primarily from agriculture and forestry. Urbanization proceeded rapidly from the 1960s onwards. Even though the Nordic welfare state was firmly established in Finland by the 1970s, old forms of agrarian poverty still remained in the culture. The source material for the study consists of 99 biographies and 502 proverbs. Biographical texts include written autobiographies and interviewed biographies. A primary analyzing concept is called a poverty speech. The poverty speech has been analyzed by providing answers to the following three questions: What connotations do people attach to poverty when they speak about it? What sort of social relations arise when people speak about poverty? How is the past experience of poverty constructed in the present and in the welfare state context? Cultural knowledge is a theoretical and analytical tool that enables people to categorize information. The three questions stated above are crucial in revealing the schematic structure that people use to communicate about agrarian poverty. Categories are analyzed and processed in terms of cultural themes that contain the ideals and stereotypes of spoken motif and sub-themes. The application of theoretical and analytical premises to the poverty speech has shown that there are four cultural themes. The first theme is Power. The social connotations in the poverty speech are mostly in relation to the better-off people. Poverty does not exist without an awareness of welfare, i.e. the understanding of a certain standard of welfare above that of one's own. The second theme is about family ties as a resource and welfare network. In poverty speech, marriage is represented as a means to upgrade one's livelihood. Family members are described as supporting one another, but at the same time as being antagonists. The third theme, Work represents the work ethic that is being connected to the poverty. Hard working as a representation is attached to eligibility for `a good life´ that in Finland was to become an owner-occupier of a cottage or a flat. The fourth theme is Security. The resentment of unfair treatment is expressed by using moral superiority and rational explanations. The ruling classes in the agrarian society are portrayed as being evil and selfish with no social conscience because they did not provide enough assistance to those who needed it. During the period when the welfare benefit system was undeveloped, the poor expected the wealthier people to make a contribution to the distribution of material wealth. In the premises of cultural knowledge, both oral and written traditions are about human thinking: they deal with topics, ideas and evaluations that are relevant to their bearers. Many elements expressed in poverty speech, such as classifications and customs derived from the rural world, have been carried over into the next generation in newer contexts and a different cultural environment. Keywords: cultural knowledge, cognitive categorization, poverty, life stories, proverbs

The superfluid as a source of all interactions

The superfluid state of fermion-antifermion fields developed in our previous papers is generalized to include higher orbital and spin states. In addition to single-particle excitations, the system is capable of having real and virtual bound or quasibound composite excitations which are akin to bosons of spinJ P equal to0 �, 1�, 2+, etc. These pseudoscalar, vector, and tensor bosons can be massive or massless and provide the vehicles for strong, electromagnetic, weak, and gravitational interactions. The concept that the basic (unmanifest) fermion-antifermion interaction can lead to a multiplicity of manifest interactions seems to provide a basis for a unified field theory.

Monikasvoinen TAVA-partisiippi : Tutkimus suomen TAVA-partisiipin käyttökonteksteista ja verbiliittojen kieliopillistumisesta

The multifaceted passive present participle in Finnish This study investigates the uses of the passive present participle in Finnish. The participle occurs in a variety of syntactic environments and exhibits a rich polysemy. Former descriptions have treated it as a mainly modal element, but it has several non-modal uses as well. The present study provides an overview of its uses and meanings, with the main focus on the factors which trigger the modal reading. In addition, the study contains two case studies on modal periphrastic constructions consisting of the verb 'to be' and the present passive participle, the Obligation construction, e.g., on men-tä-vä [is go-pass-ptc], and the Possiblity construction, e.g., on pelaste-tta-v-i-ssa [is save-pass-ptc-pl-ine]. The study is based on empirical data of 9000 sentences obtained from i) large collections of transcribed material from Finnish dialects, ii) a corpus of modern Finnish newspaper texts, iii) corpora of Old Finnish texts. Both in colloquial and standard Finnish the reading of the participle is highly dependent of the context and determined by such factors as the overall syntactic environment and other co-occurring elements. One of the main findings here is that the Finnish passive present participle is not modal per se. The contextual modal reading arises whenever the state of affairs is conceptualized from the viewpoint of the implied subject of the participle, and the meaning of possibility or obligation depends mostly on whether the situation is pleasant or undesirable. In sections examining the grammaticalization of the Possibility and Obligation constructions, the perspective is diachronic. Both constructions have derived from copula constructions with the passive present participle as a predicate (adjective or adverb). These sections show how a linguistic change can be investigated on the basis of the patterns of usage in the empirical data. The Possibility construction is currently going through a restructuration to a passive verbal complex. The source of this construction is reflected in its present-day use by the fact that it heavily biased towards a small set of verbs. The Obligation construction has grammaticalized to a construction comparable to a compound tense. Patterns of use of the construction show that grammaticalization originates in specific syntactic constructions with an implication of practical necessity. Furthermore, it is shown that the Obligation construction has grammaticalized in different directions in standard and colloquial Finnish. Differing from the study on most typical phenomena investigated in the literature on grammaticalization of modality, the present study opens new perspectives and methods for discussion on these questions.

Origin of the plateau in the low-temperature thermal conductivity of silica

Thermal conductivities of glasses at low temperatures show strikingly similar behavior irrespective of their chemical composition. While for T<1 K the thermal conductivity can be understood in the phenomenological tunneling model; the ‘‘universal plateau’’ in the temperature interval 15>T>2 K is totally unexplained. While Rayleigh scattering of phonons by structural disorder should be the natural cause for limiting the mean free path of phonons in this temperature range, it has been concluded before that in glasses a strong enough source of such scattering does not exist. In this study we show by a proper structural analysis in at least one material (namely, silica) that a strong enough source of Rayleigh scattering of phonons in glasses does exist so that the ‘‘universal plateau’’ can be explained without invoking any new mechanism. This may be for the first time that the low-temperature property of a structural glass has been correlated to its structure.

Synthesis and characterization of metal substituted AlxCr1-x(acetylacetonate)(3) single-source precursors for their application to MOCVD of thin films

A detailed study, involving the synthesis of a single-source precursor containing two metal ions sharing the same crystallographic site, has been undertaken to elucidate the use of such a single-source precursor in a CVD process for growing thin films of oxides comprising these two metals, ensuring a uniform composition and distribution of metal ions. The substituted complexes Cr1-xAlx(acac)(3), where acac = acetyl-acetonate, have been prepared by a co-synthesis method, and characterized using UV-Vis spectroscopy. TGA/DTA measurements, and single crystal X-ray diffraction at low temperature. All the studied compositions crystallize in the monoclinic space group P2(1)/c with Z = 4 in the unit cell. It was observed that the ratio (Al:Cr) of the site occupancy for the metal ions, obtained from single crystal refinement, is in agreement with the results obtained from complexometric titrations. All the solid state structures have the metal in an octahedral environment forming six-membered chelate rings. M-O acac bond lengths and disorder in the terminal carbon have been studied in detail for these substituted metal-organic complexes. One composition among these was chosen to evaluate their suitability as a single-source precursor in a LPMOCVD process (low-pressure metal-organic chemical vapour deposition) for the deposition of a substituted binary metal oxide thin film. The resulting thin films were characterized by X-ray diffraction, scanning electron microscopy, and infrared spectroscopy. (C) 2010 Elsevier Ltd. All rights reserved.