Glulam is a product that was engineered to make use of timber in a more efficient way. Bychoosing timber of similar quality and discarding natural defects during production, thedevelopment of a stronger cross-section is achieved.Carbon fiber is a relatively new material with a high tension capacity. This feature is used toexamine how the bending capacity of the beams improve by adhering carbon fiber laminateson the lower edge of the beamsThe strength of the material is tested with three experiments: carbon fiber on the bottom of thebeam (a), carbon fiber attached to the lower sides of the beam (b) and carbon fiber in thebeam, covered with a layer of wood (c) The results show that the first case, where the carbon fiber is attached to the bottom of thebeam, gave the best result with an increase in capacity of 59 % compared to the nonreinforcedcontrol. The other two cases also show an improvement in capacity, beam-type 3had a capacity increase of 47% and beam-type 4 increased with 25 %Tests were also made with glulam beams reinforced with fiberglass, but these tests were notanalyzed in depth because the purpose was to compare the capacity to carbon fiber. Thisbeam improved its capacity by 40.3%.The tests show that carbon fiber as a reinforcement material for glulam is a good choice whenthere is a requirement for stronger cross-sections in both new production and renovation ofold buildings. However there are some disadvantages to carbon fiber, for example costs andincreased demands on work environment, which makes steel a cheaper option.

Antimicrobial peptides (AMPs) are not only fast microbe-killing molecules deployed in the host defense of living organisms but also offer valuable lessons for developing new therapeutic agents. While the mode of action of AMPs is not clearly understood yet, membrane perturbation has been recognized as a crucial step in the microbial killing mechanism of many AMPs. In this thesis, we first present a physical basis for the selective membrane-disrupting activity of cationic AMPs. To this end, we present a coarse-grained physical model that approximately captures essential molecular details such as peptide amphiphilicity and lipid composition (e.g., anionic lipids). In particular, we calculate the surface coverage of peptides embedded in the lipid headgroup-tail interface and the resulting membrane-area change, in terms of peptide and membrane parameters for varying salt concentrations. We show that the threshold peptide coverage on the membrane surface required for disruption can easily be reached for microbes, but not for the host cell -- large peptide charge (≳4) is shown to be the key ingredient for the optimal activity-selectivity of AMPs (in an ambient-salt dependent way). Intriguingly, we find that in a higher-salt environment, larger charge is required for optimal activity. Inspired by membrane softening by AMPs, we also study electrostatic modification of lipid headgroups and its effects on membrane curvature. Despite its relevance, a full theoretical description of membrane electrostatics is still lacking -- in the past, membrane bending has often been considered under a few assumptions about how bending modifies lipid arrangements and surface charges. Here, we present a unified theoretical approach to spontaneous membrane curvature, C₀, in which lipid properties (e.g., packing shape) and electrostatic effects are self-consistently integrated. Our results show that C₀ is sensitive to the way lipid rearrangements and divalent counterions are modeled. Interestingly, it can change its sign in the presence of divalent counterions, thus stabilizing reverse hexagonal (H_II) phases.

Two experiments were designed to evaluate human sensitivity to elasticity. Elastic objects bend when a force is applied to them. Observers saw two computer-generated bending rods (defined by the motions of 50 dots) on any given trial and were required to judge which rod was more flexible. Elasticity difference thresholds were calculated for each observer for each of three bending conditions. The rods bent in a plane that was either frontoparallel or oriented 42.5 or 85 degrees from frontoparallel. The results showed that observers could precisely discriminate between bending rods of different elasticities, independent of whether the bendings occurred in the frontoparallel plane or in depth. To rule out the possibility that the ability to judge bending motion was based on the ability to judge 2-dimensional (2-D) speed a second experiment was conducted to obtain difference thresholds for 2-D speed. The observers' speed discrimination thresholds were not positively correlated with their elasticity discrimination thresholds, which suggests that the observers' ability to judge bending motion was not based on their capability to discriminate differences in speed.

Syftet med detta gestaltande arbete är att ta reda på hur skiktlimning fungerar i skolundervisningen och vilka möjligheter som finns för att integrera den mer i skolan. Syftet är också att bidra med kunskap om tekniken till andra lärare. Detta är ett gestaltande examensarbete. Tre olika produkter tillverkades med hjälp av skiktlimning. Processen dokumenterades så att lärare och elever ska kunna använda dem i slöjdundervisningen. Jag gjorde även fyra olika intervjuer med fyra lärare från tre olika skolor och även en undersökning om hur produkterna jag tillverkat fungerar i en skolsituation. Resultatet visar att skiktlimning är en teknik som kan vara av intresse för elever i skolan. Det är också uppenbart att lärare inte har mycket erfarenhet och kunskap om tekniken. Slöjdlärarna medger att det finns fördelar med tekniken även om den inte används ofta i undervisningen. Slutsatsen av denna studie är att skiktlimning som teknik kan användas i grundskolan men att den verkar förekomma i liten utsträckning. Min undersökning visar att det var mycket populärt bland eleverna när de väl blev introducerade och intresserade av tekniken. / The purpose of this study is to find out how laminate bending works in school and how one could integrate it even more. The purpose is also to spread awareness of this technique. This is an examinations work. I made three different items that involve the technique laminate bending. I documented them and made manuals for those so that teachers and students in school will be able to understand them. I also made four separate interviews with four different teachers from three different schools and also investigated how the products I made work in a school context. The results show that laminate bending is a technique that can be of interest to students today. It is obvious that teachers do not have much experience and knowledge about the technique. Teachers in sloyd admit the advantages of the technique even though it is not used frequently in learning processes in school. The conclusions from this study are that the technique can be used in school nowadays but it seems like it occurs in a very small extent. It is also apparent from my investigation that it is very popular among the students, once they got introduced and interested in the technique.

<p>Pediatric cervical spinal injuries are associated with high morbidity and mortality. Cervical injuries observed in the pediatric population appear to be age dependent with younger children experiencing more upper cervical level injuries compared to increased lower level cervical injury patterns to older children. The majority of pediatric cervical spinal injuries are motor vehicle crash related. Current progress in child occupant protection, including increased and proper restraint usage continues to reduce serious injury and fatalities to child occupants. However, improper restraint usage and incorrect child seating location, especially with children transitioning from rear-facing child restraints to forward-facing restraints is still a concern. Continued reductions in serious injury and fatalities to child occupants in survivable motor vehicle crashes will be based on continued education and improvements in child anthropometric test devices, child computational injury models and child restraint system design. Improvements in all of these categories are dependent on an improved understanding of the developmental biomechanics of the human cervical spine. Currently, limited data exist on human child neck biomechanics and none of the current cadaveric work has evaluated the biomechanical response over the entire age spectrum from birth to young adulthood. Numerous surrogate studies exist and have formed the basis of child injury criteria and developmental biomechanics, but have not been assessed in relation to the response of the pediatric human cervical spine. The current work investigates the biomechanics of the osteoligamentous human cervical spine from birth to young adulthood under tensile and bending loading environments. Tensile low-load and load-to-failure stiffness, load-to-failure, and flexion-extension bending stiffness increased with age. Tensile normalized displacement at failure and total bending low-load range of motion decreased with age. Viscoelastic rate effects are present in the pediatric cervical spine and are modeled with quasi-linear viscoelasticity. Peak load and loading energy increases with increased loading rate, while hysteresis energy is rate insensitive at lower loading rates, but increases at higher rates of loading. These data establish structural response behavior and injury thresholds for the osteoligamentous cervical spine by age. Additionally, they provide human data to assess the appropriateness of current surrogate models and current scaling techniques associated with these models. Finally, these data provide human response by age useful in progressing the biofidelity of computational and physical models for child occupant protection.</p> / Dissertation

In this thesis, we propose a new structure of GaP/a-Si:H/BulkSi solar cell in which the additional a-Si:H layer due to the concept of energy bandgap is used to improve the open-circuit voltage. As the a-Si:H doping concentration is increased, the upward bandgap bending is expected to be observed; hence, a high open-circuit voltage is obtained. But in this situation, the upward bandgap bending also hinders the carrier transport, leading a low short-circuit current density. It is worth noting that the proposed solar cell can have a high open-circuit voltage of 0.758 V. In addition, we carefully investigate the characteristics of wide-bandgap gallium phosphide (GaP) material used for silicon-based solar cells. According to the simulated results, the absorption of GaP is better than silicon with a wavelength below 450 nm. Also, the GaP/BulkSi solar cell is shown to have a lower reflectivity value than the conventional PN_BulkSi solar cell. Hence we can prove that the internal quantum efficiency and external quantum efficiency are improved accordingly. As a result, the short-circuit current density is increased about 10 %. In addition, the optimized parameters of a GaP/BulkSi solar cell are as follows: the short-circuit current density is 21.264 mA/cm2, the open-circuit voltage is 0.624 V, the fill factor is 82.4 %, the conversion efficiency is 11.236 %, respectively.

A finite element model based on the layer-wise theory and the von Kármán type nonlinear strains is used to analyze damage in laminated composite beams. In the formulation, the Heaviside step function is employed to express the discontinuous interlaminar displacement field at the delaminated interfaces. Two types of the most common damage modes in composite laminates are investigated for cross-ply laminated beams using a numerical approach. First, a multi-scale analysis approach to determine the influence of transverse cracks on a laminate is proposed. In the meso-scale model, the finite element model based on the classical laminate theory provides the material stiffness reduction in terms of the crack density by computing homogenized material properties of the cracked ply. The multiplication of transverse cracks is predicted in a macro-scale beam model under bending loads. In particular, a damage analysis based on nonlinear strain fields in contrast to the linear case is carried out for a moderately large deformation. Secondly, the effect of delamination in a cross-ply laminated beam under bending loads is studied for various boundary conditions with various cross-ply laminate lay-ups. The crack growth of delamination is predicted through investigating the strain energy release rate. Finally, the interactions of a transverse crack and delamination are considered for beams of different configurations. The relationships between the two different damage modes are described through the density of intralaminar cracks and the length of the interlaminar crack. It is found that geometric nonlinearity plays an important role in progression of interlaminar cracks whereas growth of intralaminar cracks is not significantly influenced. This study also shows that the mixture of fracture mode I and II should be considered for analysis of delamination under bending loads and the fracture mode leading delamination changes as the damage develops. The growth of delamination originated from the tip of the transverse crack is found to strongly depend on the thickness of 90- degree layers as well as the transverse crack density. Further, the effect of interfacial crack growth on the transverse cracking can be quatitatively determined by the delamination length, the thickness of 90-degree layers and the transverse crack density.

According to the fast development of portable electronic devices, their characteristics are inclined to miniature profile and lightweight. Nowadays, the wafer-level package (WLP) has been widely applied in portable electronic devices for its miniature profile and lightweight. It will become the mainstream trend later soon. The normal use of portable electronic devices brings low-frequency random vibrations to the electronic packages inside. Because of the increasing demand of these devices, the reliability of electronic packages subjected to repeated mechanical loads has become an important issue in the contemporary electronic packaging industry. In this paper both numerical and experimental studies were carried out to investigate the reliability life of Ultra-CSP under cyclic bending conditions. We perform four-point cyclic bending with various combinations of amplitudes and frequencies. Then, we do failure analysis in Ultra-CSP by observing the failure modes. A finite element model for the package is built up for dynamic as well as quasi-static analyses. Accumulated plastic work per bending cycle within the critical solder ball were calculated and together with the experimental results the parameters for the Coffin-Manson fatigue equation were fitted. Through finite element analysis we find that the solder ball which located in the corner has higher accumulated plastic work. Therefore, the crack in the solder ball grew more easily. Thus it lets package resistance rise to determine failure. It was observed from the bending experiments that the influence of frequencies on the fatigue life of the solder interconnects is inapparent. However, influence of amplitude is significant. From the results of both experiments and FEA, it was found that for this particular ultra-CSP specimen under cyclic bending conditions, the characteristic life was expressed as

During the bending of flange plate used for dapped girders some highway bridge fabricators are experiencing cracking of the flange plate particularly when heat is used in assisting the bending process. Due to the extreme strains experienced during the fabrication process, investigating this problem requires the use of a finite element analysis. The fabrication process was broken down into two parts, first the heating of the plate through the use of either a furnace or an acetylene torch (thermal), and the second was the bending process (structural). The five different temperatures collected during the thermal analysis were a uniform temperature of 75oF, a 1100oF uniform temperature as a result of furnace heating, both five and ten minutes of air-cooling after the plate had reached a uniform temperature of 1100oF, and the temperature gradient after heating the flange plate to a surface temperature of 1200oF though the use of an acetylene torch. After the thermal analysis was completed, the resulting temperatures were imported into the structural model. The plate thicknesses analyzed were one, one and a half, and two inches, assuming both 50 and 70 ksi yield strengths. To achieve a 90 degree six-inch radius bend the plate was bent in five separate locations. The result of this analysis showed that with the introduction of temperature gradients into thefabrication process, the strains along the plate??s extreme fibers increased. The model further showed that for both a one and a half and two-inch thick plate the extreme fiber strains exceeded ten percent, which further adds to the increased risk of the flange plate cracking during fabrication. The highest residual stresses through the plate??s thickness occurred during cold bending. The residual stresses through the plate??s thickness decreased when the fabrication process was carried out at elevated temperatures. When steel exceeds a strain of 10 to 16 percent during the fabrication process, the plate becomes susceptible to cracking. This strain limit was exceeded for plate thicknesses of one and a half and two inches.

<p>Clay, quartz and feldspar are widely available in Uganda. The location and properties of various clay deposits are reported in the literature, but little is reported on feldspar and quartz deposits. In this work an extended literature on ceramics and porcelains in particular, is documented. Samples from two deposits of feldspar and two deposits of quartz are characterised and found to possess requisite properties for making porcelain insulators. Sample porcelain bodies are made from materials collected from selected deposits using different mixing proportions of clay, feldspar and quartz. Their properties in relation to workability, firing temperature, dielectric and bending strengths are studied. It is found that a mixture consisting of 30% Mutaka kaolin, 15% Mukono ball clay, 30% Mutaka feldspar and 25% Lido beach flint yields a body with highest mechanical strength (72MPa) and dielectric strength (19kV/mm) when fired at 1250°C. The strength (both mechanical and dielectric) is found to decrease with increasing firing temperature. At high firing temperatures, the undissolved quartz in the body decreased, the glass content increases and pores are formed. Mullite content on the other hand does not change at temperatures above 1200°C but there are significant differences in the morphologies of the mullite crystals in the samples. Optimum mechanical and electrical properties are found at maximum virtification and a microstructure showing small closely packed mullite needles.</p>