Complex surface structures in nature often have remarkable optical properties. By understanding the origin of these properties, such structures may be utilized in metamaterials, giving possibilities to create materials with new specific optical properties. To simplify the optical analysis of these naturally developed surface structures there is a need to assist data analysis and analytical calculations with numerical calculations. In this work an application tool for numerical calculations of optical properties of surface structures, such as reflectances and ellipsometric angles, has been developed based on finite element methods (FEM). The data obtained from the application tool has been verified by comparison to analytical expressions in a thorough way, starting with reflection from the simplest of interfaces stepwise increasing the complexity of the surfaces. The application tool were developed within the electromagnetic module of Comsol Multiphysics and used the script language to perform post-process calculations on the obtained electromagnetic fields. The data obtained from this application tool are given in such way that easily allows for comparison with data received from spectroscopic ellipsometry measurements.

The graduation essay has been carried out in co-operation with Kalmar Industries in Lidhult, Sweden. The purpose of our essay was to develop a complete construction solution on a hoist that could lift a laying wheel, lift it up and then turn it 90 degrees. After that the wheel shall be placed in a special holder. The background of the essay is a record of reports of damage wheels when they been incorrect lifted with a forklift. The hoist shall be used together with the same forklifts that manage the wheels today. Together with our instructor at Kalmar Industries we developed a requirement specification and from that we got free hands. However this was not the main task from the beginning, then a simular hoist should be develop but used directly in the assembly workshop without using a forklift. We started to find principle solutions that later was evaluated against the requirement specification. The best proposals were analyzed by hand and in Catia V5: s FEM-module. After a couple of bettering proposal it resulted in a tenable solution. Drawings, component specification and a risk analyze was made to finally have a complete solution. Kalmar Industries decided to order material and manufacture the construction. The benefits with our construction compared to the daily solution are decreased risk of person injury, equipment-, and wheel damage. Our essay resulted in a complete construction ready to use.

As optical fiber systems evolve to higher data rates, the importance of polarization control and manipulation steadily increases. Polarization manipulating devices, such as polarization splitters and converters, can be realized by introducing material anisotropy or geometric asymmetry. Compared to active devices, passive polarization converters are more simply fabricated and controlled; therefore they have attracted increasing attention during the past two decades. However, materials employed in previous polarization rotating waveguides are mainly limited to low index-contrast III-V semiconductors such as InP and GaAs. Such III-V devices possess large radiation loss, large curvature loss, and low coupling efficiency to single-mode fibers; in addition, due to the weak optical confinement, the device spacing has to be large, which prevents high-density and large-scale integration in optoelectronic integrated circuits (OEIC) and planar lightwave circuits (PLC). <br /><br /> In this dissertation, the silicon-on-insulator (SOI) technology is introduced to the design and fabrication of passive polarization rotators (PR). Efficient and accurate full-vectorial finite-element eigenmode solvers as well as propagation schemes for characterizing novel SOI PRs are developed because commercial software packages based on finite-difference techniques are inefficient in dealing with arbitrary waveguide geometries. <br /><br /> A set of general design procedures are accordingly developed to design a series of slanted-angle polarization converters, regardless of the material system (SOI or III-V), outer-slab layer configuration (symmetric or asymmetric), and longitudinal loading (single- or multi-section). In particular, our normalized design charts and simple empirical formula for SOI polarization converters are applicable to a wide range of silicon-guiding-film thickness, e. g. , from 1 to 30 &mu;m, enabling fast and accurate polarization rotator design on most commercial SOI wafers. With these procedures, in principle 100% polarization conversion efficiency can be achieved by optimizing waveguide geometric parameters. <br /><br /> A novel configuration with asymmetric external waveguiding layers is proposed, which is advantageous for fabrication procedure, manufacturing tolerance, single-mode region, and conversion efficiency. By etching along the crystallographic plane, the angled-facet can be perfectly fabricated. Completely removing external waveguiding layer beside the sloped sidewall not only simplifies production procedures but also enhances fabrication tolerances. <br /><br /> To accurately and efficiently characterize asymmetric slanted-angle SOI polarization converters, adaptive mesh generation procedures are incorporated into our finite-element method (FEM) analysis. In addition, anisotropic perfectly-matched-layer (PML) boundary condition (BC) is employed in the beam propagation method (BPM) in order to effectively suppress reflections from the edges of the computation window. For the BPM algorithm, the power conservation is strictly monitored, the non-unitarity is thoroughly analyzed, and the inherent numerical dissipation is reduced by adopting the quasi-Crank-Nicholson scheme and adaptive complex reference index. <br /><br /> Advantages of SOI polarization rotators over III-V counterparts are studied through comprehensive research on power exchange, single-mode condition, fabrication tolerance, wavelength stability, bending characteristics, loss and coupling properties. The performance of SOI PRs is stable for wavelengths in the ITU-T <em>C</em>-band and <em>L</em>-band, making such devices quite suitable for DWDM applications. Due to the flexible cross-section of SOI polarization converters, the coupling loss to laser diodes and single mode fibers (SMF) can be designed to be very small and can be further reduced by a tapered waveguide with cross-sections always satisfying the single-mode criteria. Slanted-angle SOI polarization rotators display asymmetric bending characteristics and permit extremely small curvatures with negligible radiation loss when the angled-facet is located at the outer bend radius. Moreover, SOI polarization rotators can be manufactured with low-price processing techniques that are fully compatible with CMOS integrated circuits (IC) technology, and thus can be integrated on both photonic and electronic chips. <br /><br /> Experimental verifications have shown good agreement with theoretical analysis and have confirmed the promising characteristics of our novel asymmetric SOI polarization converters. Similar asymmetric-outer-slab geometry has recently been employed by peer researchers to fabricate high performance III-V polarization rotators. We therefore believe that results in this dissertation will contribute much to related research fields.

The mainline railway track between Dublin and Belfast in Northern Ireland was constructed during the 1850's. Substantial lengths of railway embankment were constructed over poor-quality peaty soils. This was accomplished using tree trunk fascines placed directly on the natural ground surface; with poor-quality local peaty soils used as light weight fill.<p>In recent years, Northern Ireland Railways have noticed that these sections of railway track have been deteriorating more rapidly than sections of the track where the foundations are more competent. The magnitudes of displacement of the track under train loading appear to be increasing gradually over time and train speeds have had to be reduced.<p>This thesis is based on the research done to monitor the response of these railway track and embankment structures to dynamic train loading. The displacements were monitored for two different embankments under a variety of loading conditions and for various seasonal conditions. These displacements were recorded using a sensor created for this task. The sensor consisted of a photo-sensitive array mounted on the sleepers and a laser, which was placed outside the area of influence of train loading, and shone on the photo-sensitive array. <p>Analytical (Winkler) modelling was conducted to determine the effects of train speed and the cause of the large train-induced displacements. Analytical and finite element modelling were used to determine the effectiveness of alternative methods of embankment stabilization.<p>The results from the analytical modelling suggest that the deformation of the embankment under train loading was not due to dynamic excitation, but static deformation of the poor-quality fill and soft foundation materials. From both the analytical and finite element modelling of possible remediation techniques, methods that stiffen the embankment and foundation material are shown to be the most effective at reducing the train induced deflection of the embankment.

Sammanfattning Denna studie beskriver hur elever, i skolår fem, uttrycker hälsa utifrån Antonovsky´s begrepp KASAM, en känsla av sammanhang. Genom en kvalitativ intervjustudie med öppna intervjufrågor, i grupper om tre elever, har eleverna samtalat om vad hälsa innebär för dem. Syftet med studien var att få eleverna att sätta ord på sina egna tankar kring hälsa. Resultatet visar att de har ganska goda kunskaper om vad hälsa innebär. De sätter dock inte in denna kunskap, i en övergripande beskrivning kring vad som ger känsla av sammanhang, i den egna livssituationen.

Matematik finns överallt men trots det har vi genom studien fått fram att ”det finns jättemycket luckor, att de inte förstår”.  Detta citat är hämtat ifrån en av våra intervjuer och speglar vårt resultat. Studien är kvalitativ och vi har intervjuat pedagoger samt låtit barn, i förskola och årskurs 1, utföra matematikuppgifter. I denna studie har vi fokuserat på grunderna i matematik. Syftet med studien har varit att utröna kunskaper inom antalsuppfattning hos barn. Vi har även belyst pedagogernas kunskaper inom antalsuppfattning samt hur de arbetar med detta. I studien har vi influerats av Piagets och Vygotskijs tankar om hur barn lär. Resultaten i vår studie har analyserats med inspiration av hermeneutiken. Resultaten visar att det finns okunskap hos både barn och pedagoger gällande antalsuppfattning. Det gäller bland annat barn som helt saknar kunskaper inom detta samt att pedagoger uppfattar att subitizing, se stycke 3.4., och ett till ett-principen, se stycke 3.5., är detsamma som antalsuppfattning. Pedagoger behöver djupare förståelse för de matematiska begreppen inom den grundläggande matematiken. Det i sin tur kan medföra ett tydligare matematiskt språk vilket kan underlätta kommunikationen sinsemellan. I sin tur kan det möjliggöra för pedagoger att tillsammans lättare kunna utveckla barns matematiska färdigheter som de behöver i sin vardag som vuxna samhällsmedborgare.

Ermüdungsanalyse mit Pro/Mechanica am Beispiel einer Förderschnecke

The use of B-spline interpolation functions in the finite element method (FEM) is not a new subject. B-splines have been utilized in finite elements for many reasons. One reason is the higher continuity of derivatives and smoothness of B-splines. Another reason is the possibility of reducing the required number of degrees of freedom compared to a conventional finite element analysis. Furthermore, if B-splines are utilized to represent the geometry of a finite element model, interfacing a finite element analysis program with existing computer aided design programs (which make extensive use of B-splines) is possible. While B-splines have been used in finite element analysis due to the aforementioned goals, it is difficult to find resources that describe the process of implementing B-splines into an existing finite element framework. Therefore, it is necessary to document this methodology. This implementation should conform to the structure of conventional finite elements and only require exceptions in methodology where absolutely necessary. One goal is to implement B-spline interpolation functions in a finite element framework such that it appears very similar to conventional finite elements and is easily understandable by those with a finite element background. The use of B-spline functions in finite element analysis has been studied for advantages and disadvantages. Two-dimensional B-spline and standard FEM have been compared. This comparison has addressed the accuracy as well as the computational efficiency of B-spline FEM. Results show that for a given number of degrees of freedom, B-spline FEM can produce solutions with lower error than standard FEM. Furthermore, for a given solution time and total analysis time B-spline FEM will typically produce solutions with lower error than standard FEM. However, due to a more coupled system of equations and larger elemental stiffness matrix, B-spline FEM will take longer per degree of freedom for solution and assembly times than standard FEM. Three-dimensional B-spline FEM has also been validated by the comparison of a three-dimensional model with plane-strain boundary conditions to an equivalent two-dimensional model using plane strain conditions.

ABSTRACT This thesis gathered the actual Burn-In (BI) data from one of the leading cooperation in the semiconductor industry, and analyzed the major factors¡¦ impact on BGA package solder ball deformation. The Taguchi Method was used for these analyses, and the commercial statistic software MiniTab14 was widely used on this thesis. The solder ball stress was analized by using the commercial FEM software Ansys 8.1. Some electrical characters (such as device power) can be only observed from Burn-In process, but not static acceleration tests. These effects were fully discussed in this thesis. The analyses got the result that the smaller solder ball pitch/solder ball diameter causes the more serious solder ball deformation under the specific socket vendor precondition. Burn-In time are also a significant factor for solder deformation. Basically the longer BI time cause the more serious solder deformation. The device power effect is not significant within the power sampling range of this thesis.

Rivets are widely used as a means of fastening in airframe construction industry. There are various types of riveted joints on an aircraft fuselage or on a helicopter body. Among the other types of fasteners riveted joints are preferred in such applications due to / their permanence after installation and their economical advantages. In a riveted joint, it is known that residual stresses are present as a result of the installation process. Furthermore, during the flight of an aircraft, the fuselage is loaded in one cycle and such cycles are repeated throughout the service life. As a result, the panels and the rivets are subjected to fatigue type loading. The integrity of the joint must be maintained against this combination of service loads and the residual stresses. Hence, the riveting process parameters which influence the residual stresses are utmost critical in terms of fatigue life of the hole body. In this study it is aimed to obtain an accurate numerical model of a single-lap riveted joint which is widely used in airframes. 2-D axisymmetrical and 3-D numerical models are generated using commercial finite element code ABAQUS/CAE and subsequent parametric studies are carried out on these models. The Results of both models are compared with those found in the literature. Clearance between hole and rivet shank is selected as the primary parameter to be inspected. The effects of hole clearance on the final residual stress field are examined on 2-D and 3D models. Furthermore, a through the thickness, crack on the inner panel which is initiated after installation is modeled. The crack is perpendicular to the direction of loading. It is placed to the residual tensile stress zone that surrounds the rivet hole. Hence, the effects of residual stresses are also taken into account. For a riveted joint subjected to fatigue loading, such a macroscopic crack could eventually form. In this thesis, stress intensity factors (SIF&rsquo / s) for this crack are calculated for various parameters such as clearance and crack length. These can be utilized in a subsequent fatigue crack growth analysis as the initial values or they can be used in a fracture analysis, to predict unstable crack growth due to overload (i.e. crack linking).