Freezing Point Depressions of Dilute Solutions of Alkali Metal Chlorides and Bromides

Freezing point depressions (¿Tf) of dilute solutions of several alkali metal chlorides and bromides were calculated by means of the best activity coefficient equations. In the calculations, Hückel, Hamer and Pitzer equationswere used for activity coefficients. The experimental ¿Tf values available in the literature for dilute LiCl, NaCl and KBr solutions can be predicted within experimental error by the Hückel equations used. The experimental ¿Tf values for dilute LiCl and KBr solutions can also be accurately calculated by corresponding Pitzer equations and those for dilute NaCl solutions by the Hamer equation for this salt. Neither Hamer nor Pitzer equations predict accurately the freezing points reported in the literature for LiBr and NaBr solutions. The ¿Tf values available for dilute solutions of RbCl, CsCl or CsBr are not known at the moment accurately because the existing data for these solutions are not precise. The freezing point depressions are tabulated in the present study for LiCl, NaCl and KBr solutions at several rounded molalities. The ¿Tf values in this table can be highly recommended. The activity coefficient equations used in the calculation of these values have been tested with almost allhigh-precision electrochemical data measured at 298.15 K.

Formation and Control of Trace Metal Emissions in Co-Firing of Biomass, Peat, and Wastes in Fluidised Bed Combustors

Environmentally harmful consequences of fossil fuel utilisation andthe landfilling of wastes have increased the interest among the energy producers to consider the use of alternative fuels like wood fuels and Refuse-Derived Fuels, RDFs. The fluidised bed technology that allows the flexible use of a variety of different fuels is commonly used at small- and medium-sized power plants ofmunicipalities and industry in Finland. Since there is only one mass-burn plantcurrently in operation in the country and no intention to build new ones, the co-firing of pre-processed wastes in fluidised bed boilers has become the most generally applied waste-to-energy concept in Finland. The recently validated EU Directive on Incineration of Wastes aims to mitigate environmentally harmful pollutants of waste incineration and co-incineration of wastes with conventional fuels. Apart from gaseous flue gas pollutants and dust, the emissions of toxic tracemetals are limited. The implementation of the Directive's restrictions in the Finnish legislation is assumed to limit the co-firing of waste fuels, due to the insufficient reduction of the regulated air pollutants in the existing flue gas cleaning devices. Trace metals emission formation and reduction in the ESP, the condensing wet scrubber, the fabric filter, and the humidification reactor were studied, experimentally, in full- and pilot-scale combustors utilising the bubbling fluidised bed technology, and, theoretically, by means of reactor model calculations. The core of the model is a thermodynamic equilibrium analysis. The experiments were carried out with wood chips, sawdust, and peat, and their refuse-derived fuel, RDF, blends. In all, ten different fuels or fuel blends were tested. Relatively high concentrations of trace metals in RDFs compared to the concentrations of these metals in wood fuels increased the trace metal concentrations in the flue gas after the boiler ten- to hundred-folds, when RDF was co-fired with sawdust in a full-scale BFB boiler. In the case of peat, lesser increase in trace metal concentrations was observed, due to the higher initial trace metal concentrations of peat compared to sawdust. Despite the high removal rate of most of the trace metals in the ESP, the Directive emission limits for trace metals were exceeded in each of the RDF co-firing tests. The dominat trace metals in fluegas after the ESP were Cu, Pb and Mn. In the condensing wet scrubber, the flue gas trace metal emissions were reduced below the Directive emission limits, whenRDF pellet was used as a co-firing fuel together with sawdust and peat. High chlorine content of the RDFs enhanced the mercuric chloride formation and hence the mercury removal in the ESP and scrubber. Mercury emissions were lower than theDirective emission limit for total Hg, 0.05 mg/Nm3, in all full-scale co-firingtests already in the flue gas after the ESP. The pilot-scale experiments with aBFB combustor equipped with a fabric filter revealed that the fabric filter alone is able to reduce the trace metal concentrations, including mercury, in the flue gas during the RDF co-firing approximately to the same level as they are during the wood chip firing. Lower trace metal emissions than the Directive limits were easily reached even with a 40% thermal share of RDF co-firing with sawdust.Enrichment of trace metals in the submicron fly ash particle fraction because of RDF co-firing was not observed in the test runs where sawdust was used as the main fuel. The combustion of RDF pellets with peat caused an enrichment of As, Cd, Co, Pb, Sb, and V in the submicron particle mode. Accumulation and release oftrace metals in the bed material was examined by means of a bed material analysis, mass balance calculations and a reactor model. Lead, zinc and copper were found to have a tendency to be accumulated in the bed material but also to have a tendency to be released from the bed material into the combustion gases, if the combustion conditions were changed. The concentration of the trace metal in the combustion gases of the bubbling fluidised bed boiler was found to be a summary of trace metal fluxes from three main sources. They were (1) the trace metal flux from the burning fuel particle (2) the trace metal flux from the ash in the bed, and (3) the trace metal flux from the active alkali metal layer on the sand (and ash) particles in the bed. The amount of chlorine in the system, the combustion temperature, the fuel ash composition and the saturation state of the bed material in regard to trace metals were discovered to be key factors affecting therelease process. During the co-firing of waste fuels with variable amounts of e.g. ash and chlorine, it is extremely important to consider the possible ongoingaccumulation and/or release of the trace metals in the bed, when determining the flue gas trace metal emissions. If the state of the combustion process in regard to trace metals accumulation and/or release in the bed material is not known,it may happen that emissions from the bed material rather than the combustion of the fuel in question are measured and reported.

Metal surface and subsurface inspection using nondestructive optical methods

This thesis considers nondestructive optical methods for metal surface and subsurface inspection. The main purpose of this thesis was to study some optical methods in order to find out their applicability to industrial measurements. In laboratory testing the simplest light scattering approach, measurement of specular reflectance, was used for surface roughness evaluation. Surface roughness, curvature and finishing process of metal sheets were determined by specular reflectance measurements. Using a fixed angleof incidence, the specular reflectance method might be automated for industrialinspection. For defect detection holographic interferometry and thermography were compared. Using either holographic interferometry or thermography, relativelysmall-size defects in metal plates could be revealed. Holographic techniques have some limitations for industrial measurements. On the contrary, thermography has excellent prospects for on-line inspection, especially with scanning techniques.

Origins of production errors and significance of employee empowerment in reducing production error amount in sheet metal fabricating industry

The market place of the twenty-first century will demand that manufacturing assumes a crucial role in a new competitive field. Two potential resources in the area of manufacturing are advanced manufacturing technology (AMT) and empowered employees. Surveys in Finland have shown the need to invest in the new AMT in the Finnish sheet metal industry in the 1990's. In this run the focus has been on hard technology and less attention is paid to the utilization of human resources. In manymanufacturing companies an appreciable portion of the profit within reach is wasted due to poor quality of planning and workmanship. The production flow production error distribution of the sheet metal part based constructions is inspectedin this thesis. The objective of the thesis is to analyze the origins of production errors in the production flow of sheet metal based constructions. Also the employee empowerment is investigated in theory and the meaning of the employee empowerment in reducing the overall production error amount is discussed in this thesis. This study is most relevant to the sheet metal part fabricating industrywhich produces sheet metal part based constructions for electronics and telecommunication industry. This study concentrates on the manufacturing function of a company and is based on a field study carried out in five Finnish case factories. In each studied case factory the most delicate work phases for production errors were detected. It can be assumed that most of the production errors are caused in manually operated work phases and in mass production work phases. However, no common theme in collected production error data for production error distribution in the production flow can be found. Most important finding was still that most of the production errors in each case factory studied belong to the 'human activity based errors-category'. This result indicates that most of the problemsin the production flow are related to employees or work organization. Development activities must therefore be focused to the development of employee skills orto the development of work organization. Employee empowerment gives the right tools and methods to achieve this.

Kuumalanka-anemometri virtausmittauksissa

Tässä työssä selostetaan kuumalanka-anemometrin käyttö virtausmittauksissa. Kuumalanka-anemometrilla saadaan mitattua virtausnopeuden ja -suunnan lisäksi nopeusheilahteluja. Mittaustaajuus on tyypillisesti useita kymmeniä tuhansia mittauksia sekunnissa ja signaali on jatkuva. Nykytekniikalla pystytään helposti tallentamaan mittauslaitteistolta saatu viesti tietokoneelle ja muuntamaan se nopeudeksi. Hetkellisten nopeuksien avulla voidaan laskea turbulenttisen virtauksen ominaisuuksia, kuten turbulenssin intensiteetti ja spektri. Kuumalanka-anemometrissa lämmitetään sähköisesti ohutta lankaa, joka on mitattavassa virtauksessa. Langan sähköteho on suunnilleen yhtäsuuri kuin langasta konvektiolla siirtyvä lämpöteho. Tällöin on teoreettisesti mahdollista laskea virtausnopeus lämpötehosta lämmönsiirtokorrelaatioilla. Käytännössä laitteisto joudutaan kuitenkin erikseen kalibroimaan, mutta sähkötehon teoreettista riippuvuutta konvektiosta käytetään hyväksi. Kuumalangan lämmitettävä osuus on tyypillisesti halkaisijaltaan 5 µm ja pituudeltaan noin 1 mm. Sitä käytetään pääasiassa kaasuvirtausten mittaamiseen ja valtaosassa mittauksissa virtausaineena on ilma. Kuumalanka voi olla toteutettu kuumakalvotekniikalla, jossa halkaisijaltaan noin 50 - 70 µm paksuinen kuitu on päällystetty ohuella sähköä johtavalla kalvolla. Kuumakalvoanturin ei tarvitse olla muodoltaan sylinterimäinen, se voi olla mm. kartiomainen tai kiilamainen. Erikoispäällystetyllä kuumakalvoanturilla on mahdollista mitata myös nestevirtauksia. Mitattaessa kaasuvirtauksia kuumakalvon etuna on selvästi parempi kestävyys verrattuna kuumalankaan. Nimitystä kuumalanka-anemometri käytetään yleisesti molemmista anturityypeistä Tämän työn alussa käsitellään sylinterin yli tapahtuvaan virtaukseen liittyvää virtausmekaniikkaa ja lämmönsiirtoa. Anemometrin sähköinen osa, laitteisto ja sen kalibrointi käydään läpi. Langan suuntariippuvuuden laskentaan esitetään tarvittavat yhtälöt. Työssä esitellään kolme laitteistolla tehtyä perusmittausta: anturin kohtauskulman muuttaminen, pyörähdyssymmerisen suihkun nopeuskenttä ja tuulitunnelin rajakerros. Lisäksi esitellään yksi käytännöllinen ja vaativampi mittaus, jossa on mitattu nopeusprofiili radiaalikompressorin diffuusorin loppuosassa.

DATA WAREHOUSING IN A GLOBAL METAL INDUSTRIAL COMPANY

Työn tavoittena oli selvittää, miten tietovarastointi voi tukea yrityksessä tapahtuvaa päätöksentekoa. Tietovarastokomponenttien ja –prosessien kuvauksen jälkeen on käsitelty tietovarastoprojektin eri vaiheita. Esitettyä teoriaa sovellettiin käytäntöön globaalissa metalliteollisuusyrityksessä, jossa tietovarastointikonseptia testattiin. Testauksen perusteella arvioitiin olemassa olevan tiedon tilaa sekä kahden käytetyn ohjelmiston toimivuutta tietovarastoinnissa. Yrityksen operatiivisten järjestelmien tiedon laadun todettiin olevan tutkituilta osin epäyhtenäistä ja puutteellista. Siksi tiedon suora yrityslaajuinen hyödyntäminen luotettavien ja hyvälaatuisten raporttien luonnissa on vaikeaa. Lisäksi eri yksiköiden välillä havaittiin epäyhtenäisyyttä käytettyjen liiketoiminnan käsitteiden sekä järjestelmien käyttötapojen suhteen. Testauksessa käytetyt ohjelmistot suoriutuivat perustietovarastoinnista hyvin, vaikkakin joitain rajoituksia ja erikoisuuksia ilmenikin. Työtä voidaan pitää ennen varsinaista tietovarastoprojektia tehtävänä esitutkimuksena. Jatkotoimenpiteinä ehdotetaan testauksen jatkamista nykyisillä työkaluilla kohdistaen tavoitteet konkreettisiin tuloksiin. Tiedon laadun tärkeyttä tulee korostaa koko organisaatiossa ja olemassa olevan tiedon laatua pitää parantaa tulevaisuudessa.

Designing of statically loaded sheet metal structures

The goal of this thesis is to give information to machine designers about how to design and size sheet metal structures and joints. Generally, the designing object is to lighten structures. To design structures that are light and can carry loads more effectively, designers have to be updated of new manufacturing techniques and new designing methods and criterions. With knowledge of this thesis, a designer can recognize objects and methods plus how and where it is possible to apply these new more effectively load carrying structures. The thesis gives answers to questions of corrosion and material planning, goes into joint types and manufacturing techniques of sheet metal structures. One of the main issues is to develop designers world of ideas to design right kind of products with new lasertechniques.

Offset-print mottling measurement using machine vision

Mottling is one of the key defects in offset-printing. Mottling can be defined as unwanted unevenness of print. In this work, diameter of a mottle spot is defined between 0.5-10.0 mm. There are several types of mottling, but the reason behind the problem is still not fully understood. Several commercial machine vision products for the evaluation of print unevenness have been presented. Two of these methods used in these products have been implemented in this thesis. The one is the cluster method and the other is the band-pass method. The properties of human vision system have been taken into account in the implementation of these two methods. An index produced by the cluster method is a weighted sum of the number of found spots, and an index produced by band-pass method is a weighted sum of coefficients of variations of gray-levels for each spatial band. Both methods produce larger indices for visually poor samples, so they can discern good samples from the poor ones. The difference between the indices for good and poor samples is slightly larger produced by the cluster method. 11 However, without the samples evaluated by human experts, the goodness of these results is still questionable. This comparison will be left to the next phase of the project.

Quantitative elemental analysis of dry-ashed bark and wood samples of birch, spruce and pine from south-western Finland using PIXE

A total of over 200 different samples of bark and wood of Silver birch, Norway spruce and Scots pine were analysed. Samples were taken from several areas in western Finland, some with known sources of atmospheric heavy metal emission (Harjavalta, Ykspihlaja). Also analytical data for pine needles from some sites are reported. The chemical analyses were performed by thick-target particle-induced X-ray emission (PIXE) spectrometry after preconcentration by dry ashing of samples at 550oC. The following elements were quantified in most of the samples: P, S, K, Ca, Mn, Fe, Ni, Cu, Zn, Rb, Sr, Cd, Ba and Pb. The ash percentage and the chemical composition of ashes of different wood materials were also obtained, as dry ashing was used in the analytical procedure. The variations in elemental concentrations in wood and bark of an individual tree, expressed as RSDs, were mostly in the range 10 – 20 %. For several trees of the same species sampled from small areas (< 1 ha), the variations in elemental concentrations were surprisingly high (RSDs 20 – 50 %). In the vicinity of metal plants, effects of strong atmospheric heavy metal pollution (pollution factor above 100) were observed in pine bark. The increase of heavy metal content in wood samples from the same sites was quite small. Elemental concentrations in ashes of bark and wood, from areas with no local source of atmospheric pollution, were relatively uniform. Based on this observation an alternative way of demonstrating atmospheric pollution of tree bark is discussed.

The initial oxidation of transition metal surfaces

Due to their numerous novel technological applications ranging from the example of exhaust catalysts in the automotive industry to the catalytic production of hydro- gen, surface reactions on transition metal substrates have become to be one of the most essential subjects within the surface science community. Although numerous applications exist, there are many details in the different processes that, after many decades of research, remain unknown. There are perhaps as many applications for the corrosion resistant materials such as stainless steels. A thorough knowledge of the details of the simplest reactions occuring on the surfaces, such as oxidation, play a key role in the design of better catalysts, or corrosion resistant materials in the future. This thesis examines the oxidation of metal surfaces from a computational point of view mostly concentrating on copper as a model material. Oxidation is studied from the initial oxidation to the oxygen precovered surface. Important parameters for the initial sticking and dissociation are obtained. The saturation layer is thoroughly studied and the calculated results arecompared with available experimental results. On the saturated surface, some open questions still remain. The present calculations demonstrate, that the saturated part of the surface is excluded from being chemically reactive towards the oxygen molecules. The results suggest, that the reason for the chemical activity of the saturated surface is due to a strain effect occuring between the saturated areas of the surface.

Tänään ostetaan.. vuodet Pera Pirkolana mainonnan ihmemaassa

Tutkimuksen tavoitteena on valottaa tekijöitä, jotka vaikuttivat Pera Pirkolan päätymiseen mainosmusiikin tekijäksi, sekä millaisena hän tänä päivänä näkee uravalintansa ja sen tulevaisuuden näkymät. Tutkimus toteutettiin 11.10.2006 tehdyn teemahaastattelun muodossa, joka sitten kirjoitettiin sanatarkaksi tekstiksi ja analysoitiin käyttäen laadullista sisältöanalyysiä ja järjestettiin teemojen mukaan loogisiksi kokonaisuuksiksi. Kävi ilmi, että haastateltava kokee olevansa täydellisesti itselleen sopivalla alalla, eikä voi kuvitellakaan tekevänsä mitään ainakaan kovin paljon nykyisestä toimenkuvastaan poikkeavaa. Haastateltava kuvaili avoimesti uraansa ja mm. firmansa Hot Spot syntyvaiheita. Kesällä 1985 hän oli ajautunut vappuna perustettuun Radio Cityyn töihin ja päätynyt sitä kautta tekemään radiomainontaa. Aseman yhteyteen perustettu Miracle Sound tarjosi työpaikan tuleviksi vuosiksi ennen Hot Spotin perustamista 1988. Radiomainonta Suomessa syntyi 80-luvun loppupuolella. Alan alku oli villiä aikaa. Kenelläkään ei ollut käsitystä kuinka asioita pitäisi tehdä, yrityksen ja erehdyksen kautta ala kuitenkin vuosien myötä koulutti tekijänsä. Töitä oli alan alkuaikoina vaikka muille jakaa, joten oman yrityksen perustaminen tuntui luonnolliselta jatkolta hyvin alkaneelle uralle Radio Cityssä. Alan liki olemattomat kouluttautumismahdollisuudet Suomessa ovat yksi keskeinen ongelma johon haastateltava toivoisi parannusta. Muita haastattelussa sivuttuja teemoja ovat mm. muusikoiden erilainen rooli kun tehdään musiikkia mainontaan, asiakkaan esittämät mahdolliset referenssiäänitteet haetusta musiikkityylistä ja niiden suhde omaan luovaan työhön - kuinka lähelle uskaltaa mennä sekä haastateltavan työskentelytavat ja niiden kehitys yhdessä yhtiökumppani Pekka Witikan kanssa.

Electroluminescence of silicon- and some metal oxides

In the present work electroluminescence in Si-SiO2 structures has been investigated. Electroluminescence has been recorded in the range of 250-900 nm in a system of electrolyte-insulator-semiconductor at the room temperature. The heating process of electrons in SiO2 was studied and possibility of separation it into two phases has been shown. The nature of luminescence centers and the model of its formation were proposed. This paper also includes consideration of oxide layer formation. Charge transfer mechanisms have been attended as well. The nature of electroluminescence is understood in detail. As a matter of fact, electron traps in silicon are the centers of luminescence. Electroluminescence occurs when electrons move from one trap to another. Thus the radiation of light quantum occurs. These traps appear as a result of the oxide growth. At the same time the bonds deformation of silicon atoms with SiOH groups is not excludes. As a result, dangling bonds are appeared, which are the trapping centers or the centers of luminescence.

Size Effect and Notch Size Effect in Metal Fatigue

It is a well known phenomenon that the constant amplitude fatigue limit of a large component is lower than the fatigue limit of a small specimen made of the same material. In notched components the opposite occurs: the fatigue limit defined as the maximum stress at the notch is higher than that achieved with smooth specimens. These two effects have been taken into account in most design handbooks with the help of experimental formulas or design curves. The basic idea of this study is that the size effect can mainly be explained by the statistical size effect. A component subjected to an alternating load can be assumed to form a sample of initiated cracks at the end of the crack initiation phase. The size of the sample depends on the size of the specimen in question. The main objective of this study is to develop a statistical model for the estimation of this kind of size effect. It was shown that the size of a sample of initiated cracks shall be based on the stressed surface area of the specimen. In case of varying stress distribution, an effective stress area must be calculated. It is based on the decreasing probability of equally sized initiated cracks at lower stress level. If the distribution function of the parent population of cracks is known, the distribution of the maximum crack size in a sample can be defined. This makes it possible to calculate an estimate of the largest expected crack in any sample size. The estimate of the fatigue limit can now be calculated with the help of the linear elastic fracture mechanics. In notched components another source of size effect has to be taken into account. If we think about two specimens which have similar shape, but the size is different, it can be seen that the stress gradient in the smaller specimen is steeper. If there is an initiated crack in both of them, the stress intensity factor at the crack in the larger specimen is higher. The second goal of this thesis is to create a calculation method for this factor which is called the geometric size effect. The proposed method for the calculation of the geometric size effect is also based on the use of the linear elastic fracture mechanics. It is possible to calculate an accurate value of the stress intensity factor in a non linear stress field using weight functions. The calculated stress intensity factor values at the initiated crack can be compared to the corresponding stress intensity factor due to constant stress. The notch size effect is calculated as the ratio of these stress intensity factors. The presented methods were tested against experimental results taken from three German doctoral works. Two candidates for the parent population of initiated cracks were found: the Weibull distribution and the log normal distribution. Both of them can be used successfully for the prediction of the statistical size effect for smooth specimens. In case of notched components the geometric size effect due to the stress gradient shall be combined with the statistical size effect. The proposed method gives good results as long as the notch in question is blunt enough. For very sharp notches, stress concentration factor about 5 or higher, the method does not give sufficient results. It was shown that the plastic portion of the strain becomes quite high at the root of this kind of notches. The use of the linear elastic fracture mechanics becomes therefore questionable.

Welding of Sheet metal using Modified short arc MIG/MAG welding process

In this research work, the results of an investigation dealing with welding of sheet metals with diverse air gap using FastROOT modified short arc welding method and short circuit MAG welding processes have been presented. Welding runs were made under different conditions and, during each run, the different process parameters were continuously monitored. It was found that maximum welding speed and less HAZ are reached under specific welding conditions with FastROOT method with the emphasis on arc stability. Welding results show that modified short arc exhibits a higher electrode melting coefficient and with virtually spatter free droplet transition. By adjusting the short circuit duration the penetration can be controlled with only a small change in electrode deposition. Furthermore, by mixing pulsed MIG welding with modified arc welding the working envelope of the process is greatly extended allowing thicker material sections to be welded with improved weld bead aesthetics. FastROOT is a modified short arc welding process using mechanized or automated welding process based on dip transfer welding, characterized by controlled material deposition during the short circuit of the wire electrode to the workpiece.