Hiiliteräspalkin kuitulaserhitsaus

Hitsaavassa teollisuudessa kilpailukyvyn säilyttäminen ja mahdollinen parantaminen edellyttää hitsauksen tehokkuuden nostoa. Laserhitsauksen nopeus, tarkkuus, tasainen laatu ja aikaansaatava syvä tunkeuma ovatkin vakiinnuttaneet menetelmän vankan aseman tehokkaana valmistusmenetelmänä. Sähkön ja heliumin hinnan nousu ovat pakottaneet teollisuuden miettimään entistä tehokkaampien ja ympäristöystävällisempien laserlähteiden hankkimista. Kuitulaserin korkea hyötysuhde, hyvä säteenlaatu, suuri teho ja matalat käyttökustannukset ovat herättäneet kiinnostusta laserhitsaavassa teollisuudessa. Diplomityössä keskityttiin kuitulaserhitsauksen soveltamiseen. Työn tavoitteena oli parantaa kuitulaserhitsausmenetelmän ymmärrystä ja saada käsitys siitä, miten valitaan hitsausparametrien arvot, ja soveltuuko kuitulaser teolliseen tuotantoon. Tutkimuksessa pyrittiin löytämään peruskokeilla optimaaliset hitsausparametrit, joilla syntyy hyvin tunkeutunut, vähän huokosia sisältävä, ja ulkoisesti laadukas hitsi, sekä optimaalinen hitsin tunkeumaprofiili. Lopuksi hitsausparametreja testattiin tuotteen hitsauksessa. Kuitulaser soveltuu erinomaisesti hiiliteräksen hitsaukseen ja hyvin erikoislujien terästen hitsaukseen, kun teräksen hiili- ja rikkipitoisuudet ovat matalia. Sillä on laaja parametrialue. Yleisimmät hitsausvirheet ovat vajaa hitsautumissyvyys ja huokoset. Tässä diplomityössä keskityttiin etsimään yhdelle valmistettavalle tuotteelle optimaaliset kuitulaserhitsausparametrit. Kuitulaserin laser- ja prosessiparametrien vaikutusta hitsiin ei ole juurikaan tutkittu. Diplomityön kokeiden perusteella olisi hyvä tehdä eri materiaalien jatkotutkimusta railonvalmistuksen, kuten liitoksen oksidikerroksen ja ilmaraon sekä suojakaasun, vaikutuksesta hitsiin. Kuitulaserin hyvä säteenlaatu ja muut laser-parametrit ovat tuoneet mukanaan prosessiin uusia ilmiöitä, joita on syytä tutkia lisää.

Power quality improving with virtual flux-based voltage source line converter

Line converters have become an attractive AC/DC power conversion solution in industrial applications. Line converters are based on controllable semiconductor switches, typically insulated gate bipolar transistors. Compared to the traditional diode bridge-based power converters line converters have many advantageous characteristics, including bidirectional power flow, controllable de-link voltage and power factor and sinusoidal line current. This thesis considers the control of the lineconverter and its application to power quality improving. The line converter control system studied is based on the virtual flux linkage orientation and the direct torque control (DTC) principle. A new DTC-based current control scheme is introduced and analyzed. The overmodulation characteristics of the DTC converter are considered and an analytical equation for the maximum modulation index is derived. The integration of the active filtering features to the line converter isconsidered. Three different active filtering methods are implemented. A frequency-domain method, which is based on selective harmonic sequence elimination, anda time-domain method, which is effective in a wider frequency band, are used inharmonic current compensation. Also, a voltage feedback active filtering method, which mitigates harmonic sequences of the grid voltage, is implemented. The frequency-domain and the voltage feedback active filtering control systems are analyzed and controllers are designed. The designs are verified with practical measurements. The performance and the characteristics of the implemented active filtering methods are compared and the effect of the L- and the LCL-type line filteris discussed. The importance of the correct grid impedance estimate in the voltage feedback active filter control system is discussed and a new measurement-based method to obtain it is proposed. Also, a power conditioning system (PCS) application of the line converter is considered. A new method for correcting the voltage unbalance of the PCS-fed island network is proposed and experimentally validated.

Paperin ja kartongin laserleikkauksen teknistaloudellinen kannattavuus

Diplomityö on tehty kuitumateriaalien laserleikkauksen tutkimusprojektissa ILAC/PAPER. Päätavoitteena on selvittää laserleikkauksen kustannukset ja arvioida kahden laserleikkaussovelluksen taloudellista kannattavuutta. Teoriaosassa tavoitteena on etsiä teknologiainvestoinneista piirteitä, jotka tulee ottaa huomioon hanketta suunnitellessa. Työssä esitellään myös menetelmä teknologiainvestointien arviointiin. Työssä on kolme aihepiiriä; teknologiainvestointien arviointi, laserleikkauksen perusteet ja kuitumateriaalien laserleikkauskustannuksia käsittelevä empiriaosa. Teoriaosan lähdemateriaalina on käytetty toimintolaskentaa ja teknologiainvestointeja käsiteleviä julkaisuja. Empiriaosa on koottu teollisuuden tiedonannoista, tutkimusmateriaalista ja myyntitarjouksista. Teknologiainvestointien perusteleminen on vaikeaa perinteisillä investointilaskennan menetelmillä vähäisistä suorista kustannussäästöistä johtuen. Sopiva menetelmä arvioikin hankkeet laajempina kokonaisuuksina. Laserlaitteistojen vuosittaiset kustannukset ovat suuret. Luotettavuus, huoltovapaus ja joustavuus ovat hyötyjä, jotka tekevät laserlaitteistosta kannattavan. Hankintahinta ja tuottavuus ratkaisevat investoinnin kannattavuuden.

Diodilaserin käytön edellytykset ohutlevyjen hitsauksessa

Diplomityössä tutkitaan diodilaserhitsausta mahdollisena teollisuuden menetelmänä ja menetelmän vaatimuksia hitsattaessa ohutlevyjä. Työssä tutkittavat materiaalit ovat kylmävalssattu teräs ja ruostumaton teräs sekä liitosmuotoina päittäis-, laippa- ja päällekkäisliitos. Materiaalivahvuudet ovat 0,50 mm:stä 1,50 mm:iin. Työn tavoitteena on määrittää näille kyseisille materiaaleille ja liitosmuodoille hitsausnopeus levynvahvuuden funktiona. Lisäksi käsitellään diodilaserin rakennetta, säteen muodostusta, säteen muokkaamista, säteen analysointia ja säteen turvallisuuteen liittyviä asioita. Suoritetaan vertailua käytössä oleviin muihin lasertyöstömenetelmiin konepajoissa ja tehdään arvio mahdollisen diodilaserinvestoinnin kannattavuudesta. Diodilaserhitsauskokeissa käytettiin Hämeen ammattikorkeakoulun Riihimäen yksikön 1 kW:n tehoista diodilaseria. Koekappaleet leikattiin suuntaisleikkurilla. Osalle hitsatuista kappaleista tehtiin poikittaiset vetokokeet ja mitattiin mikrokovuudet. Virheitä tutkittiin silmämääräisesti sekä radiografisella kuvauksella. Kaikille tutkituille liitoksille, materiaaleille ja vahvuuksille saatiin määriteltyä hitsausnopeudet. Tehtyjen testien perusteella suuntaisleikkurin käyttö on mahdollista. Lisäksi havaittiin suojakaasun käytön myötä, että kirkkaan sulan aiheuttama heijastavuuden kasvu edellyttää hitsausnopeuden pienentämistä.

Lidar measurement of surface melt for a temperate Alpine glacier at the seasonal and hourly scales

This study shows how a new generation of terrestrial laser scanners can be used to investigate glacier surface ablation and other elements of glacial hydrodynamics at exceptionally high spatial and temporal resolution. The study area is an Alpine valley glacier, Haut Glacier d'Arolla, Switzerland. Here we use an ultra-long-range lidar RIEGL VZ-6000 scanner, having a laser specifically designed for measurement of snow- and ice-cover surfaces. We focus on two timescales: seasonal and daily. Our results show that a near-infrared scanning laser system can provide high-precision elevation change and ablation data from long ranges, and over relatively large sections of the glacier surface. We use it to quantify spatial variations in the patterns of surface melt at the seasonal scale, as controlled by both aspect and differential debris cover. At the daily scale, we quantify the effects of ogive-related differences in ice surface debris content on spatial patterns of ablation. Daily scale measurements point to possible hydraulic jacking of the glacier associated with short-term water pressure rises. This latter demonstration shows that this type of lidar may be used to address subglacial hydrologic questions, in addition to motion and ablation measurements.

Design of flywheel generator for a diesel hybrid working machine

The aim of this work is to design a flywheel generator for a diesel hybrid working machine. In this work we perform detailed design of a generator. Mobile machines are commonly used in industry: road building machines, three harvesting machines, boring machines, trucks and other equipment. These machines work with a hydraulic drive system. This system provides good service property and high technical level. Manufacturers of mobile machines tend to satisfy all requirements of customers and modernized drive system. In this work also a description of the frequency inverter is present. Power electronics system is one of the basic parts for structures perform in the project.

High-density linkage maps fail to detect any genetic component to sex determination in a Rana temporaria family.

Sex chromosome differentiation in Rana temporaria varies strikingly among populations or families: whereas some males display well-differentiated Y haplotypes at microsatellite markers on linkage group 2 (LG2 ), others are genetically undistinguishable from females. We analysed with RADseq markers one family from a Swiss lowland population with no differentiated sex chromosomes, and where sibship analyses had failed to detect any association between the phenotypic sex of progeny and parental haplotypes. Offspring were reared in a common tank in outdoor conditions and sexed at the froglet stage. We could map a total of 2177 SNPs (1123 in the mother, 1054 in the father), recovering in both adults 13 linkage groups (= chromosome pairs) that were strongly syntenic to Xenopus tropicalis despite > 200 My divergence. Sexes differed strikingly in the localization of crossovers, which were uniformly distributed in the female but limited to chromosome ends in the male. None of the 2177 markers showed significant association with offspring sex. Considering the very high power of our analysis, we conclude that sex determination was not genetic in this family; which factors determined sex remain to be investigated.

Symptoms Have Modest Accuracy in Detecting Endoscopic and Histologic Remission in Adults With Eosinophilic Esophagitis.

BACKGROUND & AIMS: It is not clear whether symptoms alone can be used to estimate the biologic activity of eosinophilic esophagitis (EoE). We aimed to evaluate whether symptoms can be used to identify patients with endoscopic and histologic features of remission. METHODS: Between April 2011 and June 2014, we performed a prospective, observational study and recruited 269 consecutive adults with EoE (67% male; median age, 39 years old) in Switzerland and the United States. Patients first completed the validated symptom-based EoE activity index patient-reported outcome instrument and then underwent esophagogastroduodenoscopy with esophageal biopsy collection. Endoscopic and histologic findings were evaluated with a validated grading system and standardized instrument, respectively. Clinical remission was defined as symptom score <20 (range, 0-100); histologic remission was defined as a peak count of <20 eosinophils/mm(2) in a high-power field (corresponds to approximately <5 eosinophils/median high-power field); and endoscopic remission as absence of white exudates, moderate or severe rings, strictures, or combination of furrows and edema. We used receiver operating characteristic analysis to determine the best symptom score cutoff values for detection of remission. RESULTS: Of the study subjects, 111 were in clinical remission (41.3%), 79 were in endoscopic remission (29.7%), and 75 were in histologic remission (27.9%). When the symptom score was used as a continuous variable, patients in endoscopic, histologic, and combined (endoscopic and histologic remission) remission were detected with area under the curve values of 0.67, 0.60, and 0.67, respectively. A symptom score of 20 identified patients in endoscopic remission with 65.1% accuracy and histologic remission with 62.1% accuracy; a symptom score of 15 identified patients with both types of remission with 67.7% accuracy. CONCLUSIONS: In patients with EoE, endoscopic or histologic remission can be identified with only modest accuracy based on symptoms alone. At any given time, physicians cannot rely on lack of symptoms to make assumptions about lack of biologic disease activity in adults with EoE. ClinicalTrials.gov, Number: NCT00939263.

Determinação voltamétrica de metais em águas e fluidos biológicos empregando mineralização de amostras com radiação ultravioleta

This work describes the optimization of pretreatment steps for the destruction of organic matter in samples of waters and biological fluids, by using an UV irradiation system with a high power UV radiation source (400 W). The efficiency of the system constructed for the photo-decomposition of samples of model waters, natural waters and biological fluids was investigated by performing recovery experiments of the metallic species Zn(II), Cd(II), Pb(II), Cu(II), Al(III) and Fe(III). The use of UV irradiation allowed the liberation of metals bound to the organic matrix and the determination of the total content of elements in the samples.

Parallel-Operating Three-Phase Voltage Source Inverters – Circulating CurrentModeling, Analysis and Mitigation

The maximum realizable power throughput of power electronic converters may be limited or constrained by technical or economical considerations. One solution to this problemis to connect several power converter units in parallel. The parallel connection can be used to increase the current carrying capacity of the overall system beyond the ratings of individual power converter units. Thus, it is possible to use several lower-power converter units, produced in large quantities, as building blocks to construct high-power converters in a modular manner. High-power converters realized by using parallel connection are needed for example in multimegawatt wind power generation systems. Parallel connection of power converter units is also required in emerging applications such as photovoltaic and fuel cell power conversion. The parallel operation of power converter units is not, however, problem free. This is because parallel-operating units are subject to overcurrent stresses, which are caused by unequal load current sharing or currents that flow between the units. Commonly, the term ’circulatingcurrent’ is used to describe both the unequal load current sharing and the currents flowing between the units. Circulating currents, again, are caused by component tolerances and asynchronous operation of the parallel units. Parallel-operating units are also subject to stresses caused by unequal thermal stress distribution. Both of these problemscan, nevertheless, be handled with a proper circulating current control. To design an effective circulating current control system, we need information about circulating current dynamics. The dynamics of the circulating currents can be investigated by developing appropriate mathematical models. In this dissertation, circulating current models aredeveloped for two different types of parallel two-level three-phase inverter configurations. Themodels, which are developed for an arbitrary number of parallel units, provide a framework for analyzing circulating current generation mechanisms and developing circulating current control systems. In addition to developing circulating current models, modulation of parallel inverters is considered. It is illustrated that depending on the parallel inverter configuration and the modulation method applied, common-mode circulating currents may be excited as a consequence of the differential-mode circulating current control. To prevent the common-mode circulating currents that are caused by the modulation, a dual modulator method is introduced. The dual modulator basically consists of two independently operating modulators, the outputs of which eventually constitute the switching commands of the inverter. The two independently operating modulators are referred to as primary and secondary modulators. In its intended usage, the same voltage vector is fed to the primary modulators of each parallel unit, and the inputs of the secondary modulators are obtained from the circulating current controllers. To ensure that voltage commands obtained from the circulating current controllers are realizable, it must be guaranteed that the inverter is not driven into saturation by the primary modulator. The inverter saturation can be prevented by limiting the inputs of the primary and secondary modulators. Because of this, also a limitation algorithm is proposed. The operation of both the proposed dual modulator and the limitation algorithm is verified experimentally.

Spraying systems and traveling speed in the deposit and spectrum of droplets in cotton plant

ABSTRACT Tractor traveling speed can influence the quality of spraying depending on the application technology used. This study aimed to evaluate the droplet spectrum, the deposition and uniformity of spray distribution with different spraying systems and traveling speeds of a self-propelled sprayer in two phenological stages of the cotton plant (B9 and F13). The experimental design was randomized blocks and treatments were three spraying techniques: common flat spray tips; tilted flat jet with air induction, at 120 L ha-1; and rotary atomizer disk, 20 L ha-1, combined with four traveling speeds: 12, 15, 18 and 25 km h-1, with four replications. Spraying deposition was evaluated for both leaf surfaces from the cotton plant apex and base (stage B9) and middle part of the plant (stage F13) with a cupric marker. A laser particle analyzer also assessed the droplet spectrum. The centrifugal power spray system produces more homogeneous droplet spectrum and increased penetration of droplets into the canopy in both phenological stages. Variation on the operating conditions necessary for increased traveling speed negatively influences the pattern of spraying deposits.

Litium-ioniakun tasapainon hallinta

Nykyaikaisen liikkuvan sähkökäytön energianlähteenä voi toimia jopa sadoista yksittäisistä sarjaankytketyistä litium-ionikennoista muodostuva akusto. Luotettaviin mittauksiin perustuva valvonta ja käytönohjaus on erityisen tärkeää litium-ioniakuissa, jotka ovat herkkiä yli- ja alijännitteille sekä korkeille lämpötiloille. Monipuolinen hallintajärjestelmä auttaa hyödyntämään akun koko kapasiteetin sekä säilyttämään akun suorituskyvyn estämällä väärinkäytön. Tässä työssä keskitytään tarkastelemaan monikennoisten litium-ioniakkujen sovelluksissa ilmeneviä haasteita sekä eri julkaisuissa esitettyjä ratkaisumalleja akun tasapainon hallitsemiseksi.

Comparative study of the different degrees of risk of gastrointestinal stromal tumor

OBJECTIVE: To evaluate the applicability of the main categories of risk and morphological factors in the prognosis of gastrointestinal stromal tumors. METHODS: we retrospectively studied fifty-four cases of GIST, assessing the main prognostic factors of this neoplasis: risk levels, topography, size, mitotic index, necrosis, histological subtype and immunophenotype. We also verified their association and the reduction of overall survival. RESULTS: Univariate analysis showed that tumors with mitoses number greater than 5 per 50CGA (high-power fields), the presence of necrosis and a high risk for both the systems proposed by Fletcher and Miettinen had a significant association with reduced survival (p = 0.00001, 0.0056, 0.03 and 0.009, respectively). The remaining analyzed factors (size, histological subtype, topography and immunophenotype) had no such association. Multivariate analysis (Jacard index) showed that the Miettinen degree of risk was the one that best correlated with prognosis. CONCLUSION: the risk criteria of Fletcher and Miettinen are important in assessing the prognosis of patients with gastrointestinal stromal tumors, especially the latter, which adds to the mitotic index and the presence of tumor necrosis.

Suurnopeus-turbokoneroottoreiden termodynaaminen ja mekaaninen mallinnus sekä rakenneanalyysi

Tässä väitöskirjassa tarkastellaan suurnopeustekniikan eri sovelluksissa ilmeneviä roottoreihin liittyviä rakenteellisia vaatimuksia ja haasteita. Tässä yhteydessä suurnopeustekniikalla tarkoitetaan järjestelyä, jossa sähkökone (moottori, generaattori) ja toimilaite (turbiini, kompressori, puhallin) on kytketty ilman vaihdetta suoraan mekaanisesti yhteen ja jossa yhteisen roottorin pyörimisnopeus on selvästi suurempi kuin 50/60 hertsin verkosta syötetyn kaksinapaisen vaihtovirtasähkökoneen tahtinopeus. Tyypillistä suurnopeuskoneen roottorille on suuri tehotiheys ja suuri mekaaninen kuormitus. Siksi esimerkiksi sähkökoneen jäähdytys on entistä haasteellisempaa kasvavien rautahäviöiden ja pienempien lämmönsiirtopinta-alojen vuoksi. Tämän työn tavoitteet voidaan jakaa kolmeen osaan:  Yhdistetyn sähkö- ja turbokoneen roottorin mekaanisen rakenteen tarkastelu, jonka tavoitteena on pienentää lämmönkehitystä ja tehostaa kriittisten kohtien jäähdytystä. Tähän liittyy sähkömagneettisten häviöiden keskittäminen jäähdytyksen kannalta edullisiin kohtiin  Yhdistetyn sähkö- ja turbokoneen roottorin mekaanisen rakenteen tarkastelu kriittisten ominaistaajuuksien kannalta  Yhdistetyn sähkö- ja turbokoneen roottorin mekaanisen rakenteen analysointi lujuustekniseltä kannalta. Tähän liittyvät mm. erilaiset ahdistussovitteet ja niiden säilyminen korkeilla pyörimisnopeuksilla sekä niiden roottoria jäykistävä vaikutus ja lämmön johtuminen kyseisissä liitospinnoissa. Tämän työn tieteellinen uutuusarvo on nimenomaan yhdistetyn sähkö- ja turbokoneen roottorin rakenteen analysointi ottamalla samanaikaisesti huomioon kaikki edellä mainitut näkökohdat: jäähtyminen erityisen kuumissa kohdissa, sähköisten häviöiden alentaminen ja niiden jakautuman huomioon ottaminen, roottorin jäykkyyden maksimointi, lujuusrasitusten hallinta ja rakenteen mekaaninen stabiliteetti sekä lämpöteknisten ylimenovastusten tarkastelu.

Permanent magnet synchronous generator design solution for large directdrive wind turbines: Thermal behavior of the LC DD-PMSG

Wind is one of the most compelling forms of indirect solar energy. Available now, the conversion of wind power into electricity is and will continue to be an important element of energy self-sufficiency planning. This paper is one in a series intended to report on the development of a new type of generator for wind energy; a compact, high-power, direct-drive permanent magnet synchronous generator (DD-PMSG) that uses direct liquid cooling (LC) of the stator windings to manage Joule heating losses. The main param-eters of the subject LC DD-PMSG are 8 MW, 3.3 kV, and 11 Hz. The stator winding is cooled directly by deionized water, which flows through the continuous hollow conductor of each stator tooth-coil winding. The design of the machine is to a large degree subordinate to the use of these solid-copper tooth-coils. Both steady-state and timedependent temperature distributions for LC DD-PMSG were examined with calculations based on a lumpedparameter thermal model, which makes it possible to account for uneven heat loss distribution in the stator conductors and the conductor cooling system. Transient calculations reveal the copper winding temperature distribution for an example duty cycle during variable-speed wind turbine operation. The cooling performance of the liquid cooled tooth-coil design was predicted via finite element analysis. An instrumented cooling loop featuring a pair of LC tooth-coils embedded in a lamination stack was built and laboratory tested to verify the analytical model. Predicted and measured results were in agreement, confirming the predicted satisfactory operation of the LC DD-PMSG cooling technology approach as a whole.