Mode of forcing a passage through the ice

Englantilaisen tutkimusmatkaajan E. D. Clarken Ahvenanmeren ylitys joulukuussa 1799. - Digitoitu valokuvasta, joka julkaistu kirjassa: R. Knapas & P. Koistinen, Historiallisia kuvia, 1993.

Perilous passage on the ice

London : Joseph Mawman 1802

Muodonmuutoksia ja näkymättömiä yhteyksiä : yine-lasten syntymään liittyvät rajoitukset Itä-Perussa

Abstract: Transformations and invisible linkages : birth-related restrictions among the Yine of Eastern Peru

Computational and Experimental Analysis of Flow Field in the Diffusers of Centrifugal Compressors

Centrifugal compressors are widely used for example in process industry, oil and gas industry, in small gas turbines and turbochargers. In order to achieve lower consumption of energy and operation costs the efficiency of the compressor needs to be improve. In the present work different pinches and low solidity vaned diffusers were utilized in order to improve the efficiency of a medium size centrifugal compressor. In this study, pinch means the decrement of the diffuser flow passage height. First different geometries were analyzed using computational fluid dynamics. The flow solver Finflo was used to solve the flow field. Finflo is a Navier-Stokes solver. The solver is capable to solve compressible, incompressible, steady and unsteady flow fields. Chien's k-e turbulence model was used. One of the numerically investigated pinched diffuser and one low solidity vaned diffuser were studied experimentally. The overall performance of the compressor and the static pressure distribution before and after the diffuser were measured. The flow entering and leaving the diffuser was measured using a three-hole Cobra-probe and Kiel-probes. The pinch and the low solidity vaned diffuser increased the efficiency of the compressor. Highest isentropic efficiency increment obtained was 3\% of the design isentropic efficiency of the original geometry. It was noticed in the numerical results that the pinch made to the hub and the shroud wall was most beneficial to the operation of the compressor. Also the pinch made to the hub was better than the pinchmade to the shroud. The pinch did not affect the operation range of the compressor, but the low solidity vaned diffuser slightly decreased the operation range.The unsteady phenomena in the vaneless diffuser were studied experimentally andnumerically. The unsteady static pressure was measured at the diffuser inlet and outlet, and time-accurate numerical simulation was conducted. The unsteady static pressure showed that most of the pressure variations lay at the passing frequency of every second blade. The pressure variations did not vanish in the diffuser and were visible at the diffuser outlet. However, the amplitude of the pressure variations decreased in the diffuser. The time-accurate calculations showed quite a good agreement with the measured data. Agreement was very good at the design operation point, even though the computational grid was not dense enough inthe volute and in the exit cone. The time-accurate calculation over-predicted the amplitude of the pressure variations at high flow.

Modeling the transport phenomena within arterial wall: porous media approach

The transport of macromolecules, such as low-density lipoprotein (LDL), and their accumulation in the layers of the arterial wall play a critical role in the creation and development of atherosclerosis. Atherosclerosis is a disease of large arteries e.g., the aorta, coronary, carotid, and other proximal arteries that involves a distinctive accumulation of LDL and other lipid-bearing materials in the arterial wall. Over time, plaque hardens and narrows the arteries. The flow of oxygen-rich blood to organs and other parts of the body is reduced. This can lead to serious problems, including heart attack, stroke, or even death. It has been proven that the accumulation of macromolecules in the arterial wall depends not only on the ease with which materials enter the wall, but also on the hindrance to the passage of materials out of the wall posed by underlying layers. Therefore, attention was drawn to the fact that the wall structure of large arteries is different than other vessels which are disease-resistant. Atherosclerosis tends to be localized in regions of curvature and branching in arteries where fluid shear stress (shear rate) and other fluid mechanical characteristics deviate from their normal spatial and temporal distribution patterns in straight vessels. On the other hand, the smooth muscle cells (SMCs) residing in the media layer of the arterial wall respond to mechanical stimuli, such as shear stress. Shear stress may affect SMC proliferation and migration from the media layer to intima. This occurs in atherosclerosis and intimal hyperplasia. The study of blood flow and other body fluids and of heat transport through the arterial wall is one of the advanced applications of porous media in recent years. The arterial wall may be modeled in both macroscopic (as a continuous porous medium) and microscopic scales (as a heterogeneous porous medium). In the present study, the governing equations of mass, heat and momentum transport have been solved for different species and interstitial fluid within the arterial wall by means of computational fluid dynamics (CFD). Simulation models are based on the finite element (FE) and finite volume (FV) methods. The wall structure has been modeled by assuming the wall layers as porous media with different properties. In order to study the heat transport through human tissues, the simulations have been carried out for a non-homogeneous model of porous media. The tissue is composed of blood vessels, cells, and an interstitium. The interstitium consists of interstitial fluid and extracellular fibers. Numerical simulations are performed in a two-dimensional (2D) model to realize the effect of the shape and configuration of the discrete phase on the convective and conductive features of heat transfer, e.g. the interstitium of biological tissues. On the other hand, the governing equations of momentum and mass transport have been solved in the heterogeneous porous media model of the media layer, which has a major role in the transport and accumulation of solutes across the arterial wall. The transport of Adenosine 5´-triphosphate (ATP) is simulated across the media layer as a benchmark to observe how SMCs affect on the species mass transport. In addition, the transport of interstitial fluid has been simulated while the deformation of the media layer (due to high blood pressure) and its constituents such as SMCs are also involved in the model. In this context, the effect of pressure variation on shear stress is investigated over SMCs induced by the interstitial flow both in 2D and three-dimensional (3D) geometries for the media layer. The influence of hypertension (high pressure) on the transport of lowdensity lipoprotein (LDL) through deformable arterial wall layers is also studied. This is due to the pressure-driven convective flow across the arterial wall. The intima and media layers are assumed as homogeneous porous media. The results of the present study reveal that ATP concentration over the surface of SMCs and within the bulk of the media layer is significantly dependent on the distribution of cells. Moreover, the shear stress magnitude and distribution over the SMC surface are affected by transmural pressure and the deformation of the media layer of the aorta wall. This work reflects the fact that the second or even subsequent layers of SMCs may bear shear stresses of the same order of magnitude as the first layer does if cells are arranged in an arbitrary manner. This study has brought new insights into the simulation of the arterial wall, as the previous simplifications have been ignored. The configurations of SMCs used here with elliptic cross sections of SMCs closely resemble the physiological conditions of cells. Moreover, the deformation of SMCs with high transmural pressure which follows the media layer compaction has been studied for the first time. On the other hand, results demonstrate that LDL concentration through the intima and media layers changes significantly as wall layers compress with transmural pressure. It was also noticed that the fraction of leaky junctions across the endothelial cells and the area fraction of fenestral pores over the internal elastic lamina affect the LDL distribution dramatically through the thoracic aorta wall. The simulation techniques introduced in this work can also trigger new ideas for simulating porous media involved in any biomedical, biomechanical, chemical, and environmental engineering applications.

Neuropeptide Y at the cellular level – Studies on PreproNPY L7P Polymorphism and the Mitochondrial Form of NPY

Neuropeptide Y (NPY) is a widely expressed neurotransmitter in the central and peripheral nervous systems. Thymidine 1128 to cytocine substitution in the signal sequence of the preproNPY results in a single amino acid change where leucine is changed to proline. This L7P change leads to a conformational change of the signal sequence which can have an effect on the intracellular processing of NPY. The L7P polymorphism was originally associated with higher total and LDL cholesterol levels in obese subjects. It has also been associated with several other physiological and pathophysiological responses such as atherosclerosis and T2 diabetes. However, the changes on the cellular level due to the preproNPY signal sequence L7P polymorphism were not known. The aims of the current thesis were to study the effects of the [p.L7]+[p.L7] and the [p.L7]+[p.P7] genotypes in primary cultured and genotyped human umbilical vein endothelial cells (HUVEC), in neuroblastoma (SK-N-BE(2)) cells and in fibroblast (CHO-K1) cells. Also, the putative effects of the L7P polymorphism on proliferation, apoptosis and LDL and nitric oxide metabolism were investigated. In the course of the studies a fragment of NPY targeted to mitochondria was found. With the putative mitochondrial NPY fragment the aim was to study the translational preferences and the mobility of the protein. The intracellular distribution of NPY between the [p.L7]+[p.L7] and the [p.L7]+[p.P7] genotypes was found to be different. NPY immunoreactivity was prominent in the [p.L7]+[p.P7] cells while the proNPY immunoreactivity was prominent in the [p.L7]+[p.L7] genotype cells. In the proliferation experiments there was a difference in the [p.L7]+[p.L7] genotype cells between early and late passage (aged) cells; the proliferation was raised in the aged cells. NPY increased the growth of the cells with the [p.L7]+[p.P7] genotype. Apoptosis did not seem to differ between the genotypes, but in the aged cells with the [p.L7]+[p.L7] genotype, LDL uptake was found to be elevated. Furthermore, the genotype seemed to have a strong effect on the nitric oxide metabolism. The results indicated that the mobility of NPY protein inside the cells was increased within the P7 containing constructs. The existence of the mitochondria targeted NPY fragment was verified, and translational preferences were proved to be due to the origin of the cells. Cell of neuronal origin preferred the translation of mature NPY (NPY1-36) when compared to the non neuronal cells that translated both, NPY and the mitochondrial fragment of NPY. The mobility of the mitochondrial fragment was found to be minimal. The functionality of the mitochondrial NPY fragment remains to be investigated. L7P polymorphism in the preproNPY causes a series of intracellular changes. These changes may contribute to the state of cellular senescence, vascular tone and lead to endothelial dysfunction and even to increased susceptibility to diseases, like atherosclerosis and T2 diabetes.

Fatigue analysis of brackets with and without scallop for bridge and other deck structure using effective notch stress.

Due to functional requirement of a structural detail brackets with and without scallop are frequently used in bridges, decks, ships and offshore structure. Scallops are designed to serve as passage way for fluids, to reduce weld length and plate distortions. Moreover, scallops are used to avoid intersection of two or more welds for the fact that there is the presence of inventible inherent initial crack except for full penetrated weld and the formation of multi-axial stress state at the weld intersection. Welding all around the scallop corner increase the possibility of brittle fracture even for the case the bracket is not loaded by primary load. Avoiding of scallop will establish an initial crack in the corner if bracket is welded by fillet welds. If the two weld run pass had crossed, this would have given a 3D residual stress situation. Therefore the presences and absence of scallop necessitates the 3D FEA fatigue resistance of both types of brackets using effective notch stress approach ( ). FEMAP 10.1 with NX NASTRAN was used for the 3D FEA. The first and main objective of this research was to investigate and compare the fatigue resistance of brackets with and without scallop. The secondary goal was the fatigue design of scallops in case they cannot be avoided for some reason. The fatigue resistance for both types of brackets was determined based on approach using 1 mm fictitiously rounded radius based on IIW recommendation. Identical geometrical, boundary and loading conditions were used for the determination and comparison of fatigue resistance of both types of brackets using linear 3D FEA. Moreover the size effect of bracket length was also studied using 2D SHELL element FEA. In the case of brackets with scallop the flange plate weld toe at the corner of the scallop was found to exhibit the highest and made the flange plate weld toe critical for fatigue failure. Whereas weld root and weld toe at the weld intersections were the highly stressed location for brackets without scallop. Thus weld toe for brackets with scallop, and weld root and weld toe for brackets without scallop were found to be the critical area for fatigue failure. Employing identical parameters on both types of brackets, brackets without scallop had the highest except for full penetrated weld. Furthermore the fatigue resistance of brackets without scallop was highly affected by the lack of weld penetration length and it was found out that decreased as the weld penetration was increased. Despite the fact that the very presence of scallop reduces the stiffness and also same time induce stress concentration, based on the 3D FEA it is worth concluding that using scallop provided better fatigue resistance when both types of brackets were fillet welded. However brackets without scallop had the highest fatigue resistance when full penetration weld was used. This thesis also showed that weld toe for brackets with scallop was the only highly stressed area unlike brackets without scallop in which both weld toe and weld root were the critical locations for fatigue failure when different types of boundary conditions were used. Weld throat thickness, plate thickness, scallop radius, lack of weld penetration length, boundary condition and weld quality affected the fatigue resistance of both types of brackets. And as a result, bracket design procedure, especially welding quality and post weld treatment techniques significantly affect the fatigue resistance of both type of brackets.

The intrinsic mechanisms of softwood fiber damage in brown stock fiber line unit operations Lappeenranta 2010

The effects of pulp processing on softwood fiber properties strongly influence the properties of wet and dry paper webs. Pulp strength delivery studies have provided observations that much of the strength potential of long fibered pulp is lost during brown stock fiber line operations where the pulp is merely washed and transferred to the subsequent processing stages. The objective of this work was to study the intrinsic mechanisms which maycause fiber damage in the different unit operations of modern softwood brown stock processing. The work was conducted by studying the effects of industrial machinery on pulp properties with some actions of unit operations simulated in laboratory scale devices under controlled conditions. An optical imaging system was created and used to study the orientation of fibers in the internal flows during pulp fluidization in mixers and the passage of fibers through the screen openings during screening. The qualitative changes in fibers were evaluated with existing and standardized techniques. The results showed that each process stage has its characteristic effects on fiber properties: Pulp washing and mat formation in displacement washers introduced fiber deformations especially if the fibers entering the stage were intact, but it did not decrease the pulp strength properties. However, storage chests and pulp transfer after displacement washers contributed to strength deterioration. Pulp screening proved to be quite gentle, having the potential of slightly evening out fiber deformations from very deformed pulps and vice versa inflicting a marginal increase in the deformation indices if the fibers were previously intact. Pulp mixing in fluidizing industrial mixers did not have detrimental effects on pulp strength and had the potential of slightly evening out the deformations, provided that the intensity of fluidization was high enough to allow fiber orientation with the flow and that the time of mixing was short. The chemical and mechanical actions of oxygen delignification had two distinct effects on pulp properties: chemical treatment clearly reduced pulp strength with and without mechanical treatment, and the mechanical actions of process machinery introduced more conformability to pulp fibers, but did not clearly contribute to a further decrease in pulp strength. The chemical composition of fibers entering the oxygen stage was also found to affect the susceptibility of fibers to damage during oxygen delignification. Fibers with the smallest content of xylan were found to be more prone to irreversibledeformations accompanied with a lower tensile strength of the pulp. Fibers poor in glucomannan exhibited a lower fiber strength while wet after oxygen delignification as compared to the reference pulp. Pulps with the smallest lignin content on the other hand exhibited improved strength properties as compared to the references.

Mikkelin Pursialan pohjavesialueen haitta-aineet

Mikkelin talousvedestä kahden kolmasosan tullessa Pursialan pohjavesialueelta on alueen suojeleminen tärkeää. Pohjaveden laatua uhkaavat etenkin alueella sattuneet pohjavedenpilaantumistapaukset. Merkittävimmät pohjaveden pilaantumistapaukset ovat VAPO Oy:n sahan aiheuttama pohjaveden pilaantuminen kloorifenoleilla (CP) ja VR:n ratapölkkykyllästämön aiheuttama pohjaveden pilaantuminen kreosoottiöljyllä sekä Rinnekadun Nesteen aiheuttama pohjaveden pilaantuminen MTBE:llä. Alueella on tehty tutkimuksia ja kunnostuksia pilaantumiin liittyen, mutta näiden tuloksia ei ole aikaisemmin koottu yhteen. Tämän työn tavoitteena oli koota tulokset samaan aineistoon. Työssä keskityttiin kloorifenolien leviämisen tarkasteluun sen Pursialan pohjavedenottamolle muodostaman suurimman uhan vuoksi. Kallioperätietojen, maanpintatietojen ja näytetietojen pohjalta laadittiin myös pienoismalli CP-pilaantuman leviämisen kokonaiskuvan hahmottamiseksi. Työn tavoitteena oli lisäksi tehdä riskitarkastelua CP-pilaantumaan liittyen ja etsiä keinoja hallita havaittuja riskejä. Riskinhallintaan liittyen työssä tutkittiin kloorifenoleilla pilaantuneen alueen maaperä- ja kalliotietoja sekä pohjaveden laatutietoja. Pursialan pohjavedessä on runsaasti rautaa ja mangaania sekä aggressiivista hiilihappoa. Pohjaveden pH on alueella noin 6,5, lämpötila noin 7,5 ºC ja happipitoisuus noin 0,7 mg/l. Pursialan kaupunginalueen kallioperässä on havaittavissa VAPO Oy:n sahalta vedenottamolle etenevä kalliopainanne, jota pitkin CP etenee. Alueen kallioperä on kiillegneissiä, jossa on pohjois–etelä-suuntaista rakoilua. Maaperätuloksien perusteella on havaittavissa vettä hyvin johtavien maakerrosten jatkuminen koko vedenottamon ja sahan välisen matkan, mikä tarkoittaa, että CP-pitoisella pohjavedellä voi olla aiemmin oletettua nopeampikin yhteys sahalta vedenottamolle. Suurin CP-pitoisuus noin 100 000 µg/l on mitattu KY-5-altaan kohdalle asennetun M14-pohjavesiputken pohjasta. Talousvesiasetuksen raja-arvo CP:lle on 10 µg/l. Sahan ja vedenottamon puolivälissä on havaittu yli 10 000 µg/l meneviä CP-pitoisuuksia. Suurin vedenottamon kaivoista (kaivo 10) mitattu pitoisuus on 149 µg/l. Jakotukilta raakavedestä otetuissa näytteissä tai talousvedessä ei ole kuitenkaan havaittu talousvesiasetuksen ylittäviä CP-pitoisuuksia. Pienoismallin perusteella CP sijaitsee sahan alueella lähellä kallionpintaa ja hajaantuu koko pohjavesipatjaan vedenottamolle päin mentäessä. CP-mittaustuloksissa on havaittavissa pulssimaisuutta. Tämä johtuu todennäköisesti Saimaan pinnan vaihtelun seurauksena muuttuvasta rantaimeytyneen pohjaveden määrästä. Saimaan pinnan nousu näyttäisi tuloksien perusteella nostavan CP-pitoisuuksia saha-alueella ja laskevan lähellä vedenottamoa. Pohjaveden pintatietojen perusteella tehdyn tarkastelun mukaan pohjavesi voi kulkeutua sahalta vedenottamolle parhaimmillaan noin vuodessa. Työssä arvioitiin KY-5–liuoksen vuosittaiseksi käyttömääräksi noin 648–970 m3. Allassakkaa arvioitiin syntyneen yhteensä noin 10–31 m3. Pohjaveteen arvioitiin joutuneen toiminnan aikana yhteensä noin 3 000–4 000 kg CP:tä. Kloorifenolit esiintyvät pohjavedessä lähes täysin kloorifenolaatteina. Kloorifenolien hajoaminen ja muuntuminen pohjavedessä on epätodennäköistä. Käsitteellisen mallin mukaan kloorifenolipilaantuman suurimmat riskit aiheutuvat kloorifenolien mahdollisuudesta pilata Pursialan vedenottamon talousvesi. Tällä hetkellä riskejä hallitaan kloorifenolien leviämisen tarkkailulla, sahan ja vedenottamon puolivälissä sijaitsevalla koepumppauksella sekä varautumalla aktiivihiilijauheen syöttöön talousvesiprosessiin. Koepumppauksen avulla on saatu ylös tällä hetkellä noin 69 kg kloorifenoleita. Tutkimuksen perusteella suositeltavimmat riskinhallintatoimet tulevaisuudessa ovat sahalla sijaitseva kunnostuspumppaus, sahan ja vedenottamon väliin sijoittuva suojapumppaus- ja vesiverhoyhdistelmä sekä sahan rannan kautta tapahtuvan rantaimeytymisen estäminen.

Effectiveness of Pilotage

The objective of the pilotage effectiveness study was to come up with a process descrip-tion of the pilotage procedure, to design performance indicators based on this process description, to be used by Finnpilot, and to work out a preliminary plan for the imple-mentation of the indicators within the Finnpilot organisation. The theoretical aspects of pilotage as well as the guidelines and standards used were determined through a literature review. Based on the literature review, a process flow model with the following phases was created: the planning of pilotage, the start of pilo-tage, the act of pilotage, the end of pilotage and the closing of pilotage. The model based on the literature review was tested through interviews and observation of pilotage. At the same time an e-mail survey directed at foreign pilotage organisations, which included a questionnaire concerning their standards and management systems, operations procedures, measurement tools and their attitude to the passage planning, was conducted. The main issues in the observations and interviews were the passage plan and the bridge team co-operation. The phases of the pilotage process model emerged in both the pilotage activities and the interviews whereas bridge team co-operation was relatively marginal. Most of the pilotage organisations, who responded to the query, also use some standard-based management system. All organisations who answered the survey use some sort of a pilotage process model. According to the query, the main measuring tools for pilotage are statistical information concerning pilotage and the organisations, the customer feedback surveys, and financial results. Attitudes to-wards passage planning were mostly positive among the organisations. A workshop with pilotage experts was arranged where the process model constructed on the basis of the literature review was tuned to match practical pilotage. In the workshop it was determined that certain phases and the corresponding tasks, through which pilo-tage can be described as a process, were identifiable in all pilotage. The result of the workshop was a complemented process model, which separates incoming and outgoing traffic, as well as the fairway pilotage and harbour pilotage from each other. Addition-ally indicators divided according to the data gathering method were defined. Data con-cerning safety and traffic flow is gathered in the form of customer feedback. The pilot's own perceptions of the pilotage process are gathered through self-assessment. The measurement data which is connected to the phases of the pilotage process is generated e.g. by gathering statistics of the success of the pilot dispatches, the accuracy of the pi-lotage and the incidents that occurred during the pilotage, near misses, deviations and accidents. The measurement data is collected via the PilotWeb at the closing of the pilo-tage. A separate project and a project group with pilots also participating will be established for the deployment of the performance indicators. The phases of the project are: the definition phase, the implementation phase and the deployment phase. The purpose of the definition phase is to prepare questions for ship commanders concerning the cus-tomer feedback questionnaire and also to work out the self-assessment queries and the queries concerning the process indicators.

Simulation of Solid Processes by Aspen Plus

Solid processes are used for obtaining the valuable minerals. Due to their worth, it is obligatory to perform different experiments to determine the different values of these minerals. With the passage of time, it is becoming more difficult to carry out these experiments for each mineral for different characteristics due to high labor costs and consumption of time. Therefore, scientists and engineers have tried to overcome this issue. They made different software to handle this problem. Aspen is one of those software for the calculation of different parameters. Therefore, the aim of this report was to do simulation for solid processes to observe different effect for minerals. Different solid processes like crushing, screening; filtration and crystallization were simulated by Aspen Plus. The simulation results are obtained by using this simulation software and they are described in this thesis. It was noticed that the results were acceptable for all solid processes. Therefore, this software can be used for the designing of crushers by calculating the power consumption of crushers, can design the filter and for the calculation of material balance for all processes.

Two-dimensional atom localization and Raman cooling of tripod-type atoms

Both atom localization and Raman cooling, considered in the thesis, reflect recent progress in the area of all-optical methods. We focus on twodimensional (2D) case, using a four-level tripod-type atomic scheme for atom localization within the optical half-wavelength as well as for efficient subrecoil Raman cooling. In the first part, we discuss the principles of 1D atom localization, accompanying by an example of the measurement of a spontaneously-emitted photon. Modifying this example, one archives sub-wavelength localization of a three-level -type atom, measuring the population in its upper state. We go further and obtain 2D sub-wavelength localization for a four-level tripod-type atom. The upper-state population is classified according to the spatial distribution, which in turn forms such structures as spikes, craters and waves. The second part of the thesis is devoted to Raman cooling. The cooling process is controlled by a sequence of velocity-selective transfers from one to another ground state. So far, 1D deep subrecoil cooling has been carried out with the sequence of square or Blackman pulses, applied to -type atoms. In turn, we discuss the transfer of atoms by stimulated Raman adiabatic passage (STIRAP), which provides robustness against the pulse duration if the cooling time is not in any critical role. A tripod-type atomic scheme is used for the purpose of 2D Raman cooling, allowing one to increase the efficiency and simplify the realization of the cooling.