This thesis presents research on the force and deflection behavior of beams with rectangular cross-sections undergoing lateral torsional buckling. The large 3-D deflection path of buckling beam tips was closely approximated by circular arcs in two planes. A new chain algorithm element was created from pseudo-rigid-body segments and used in a chain calculation that accurately predicted the force deflection relationship of beams with large 3-D deflections.

Visual effects for film and animation often require simulated granular materials, such as sand, wheat, or dirt, to meet a director's needs. Simulating granular materials can be time consuming, in both computation and labor, as these particulate materials have complex behavior and an enormous amount of small-scale detail. Furthermore, a single cubic meter of granular material, where each grain is a cubic millimeter, would contain a billion granules, and simulating all such interacting granules would take an impractical amount of time for productions. This calls for a simplified model for granular materials that retains high surface detail and granular behavior yet requires significantly less computational time. Our proposed method simulates a minimal number of individual granules while retaining particulate detail on the surface by supporting surface particles with simplified interior granular models. We introduce a multi-state model where, depending on the material state of the interior granules, we replace interior granules with a simplified simulation model for the state they are in and automate the transitions between those states. The majority of simulation time can thus be focused on visible portions of the material, reducing the time spent on non-visible portions, while maintaining the appearance and behavior of the mass as a whole.

Proteins often carry an intrinsic electric dipole moment, which can interact with external electric fields and cause protein motion. Previous research has found that the orientation of small proteins in gas phase can be controlled in a static electric field. This effect is hoped to benefit applications such as single-particle imaging, and possibly other techniques involving proteins in electric fields. With the purpose of improving our understanding and modeling of protein orientation, this project investigated the scarcely explored quantum mechanical aspects of the process, namely the polarizability. Ground-state electronic structure simulations of three small model proteins, ubiquitin, Trp-cage and lysozyme, under the influence of electric fields were performed in vacuum. The electric dipole moments of the proteins were extracted from simulations with an applied electric field of strength 1 V/nm for varying angles, with respect to a body fixed reference frame. A Python program was written to analyze and visualize the results. The results point to a connection between the polarizability and the structure of the proteins, as well as size. Next a 3D rigid rotor model was developed using Mathematica in order to study the orientation dynamics classically in a simplified and time efficient way, with the possibility of including the previous quantum results. A comparison between a simulation of ubiquitin with and without polarizability concluded that the polarizability seems to have a damping effect on the orientation dynamics, at least for the initial conditions tested in this study. Further research is necessary to validate the model and perform statistical analysis of many simulations with varying initial conditions. / Proteiner bär ofta på ett inneboende elektriskt dipolmoment, som vid interaktion med externa elektriska fält och orsakar rörelse hos proteinerna. Tidigare studier har funnit att orienteringen av små proteiner i gasfas kan kontrolleras i ett statiskt elektriskt fält. Den effekten kan förhoppningsvis vara en fördel i tillämpningar såsom single-particle imaging, och eventuellt andra tekniker som innefattar proteiner i elektriska fält. I syftet att förbättra vår förståelse och modellering av protein-orientering, har detta projekt undersökt de föga utforskade kvantmekaniska aspekterna av processen, nämligen polariserbarheten. Kvant-baserade simuleringar av grundtillståndet av tre små proteiner, ubiquitin, Trp-cage och lysozym, under påverkan av elektriska fält utfördes i vakuum. Proteinernas elektriska dipolmoment extraherades från simuleringar med ett elektriskt fält med styrkan 1 V/nm för olika vinklar, med avseende på ett kroppsfixerat koordinatsystem. Ett Python-program skrevs för att analysera och visualisera resultaten. Resultaten tyder på att polariserbarheten beror på strukturen och storleken av proteinerna. Därefter utformades en stel-rotor-modell med hjälp av Mathematica för att studera prienteringen klassiskt på ett förenklat och tidseffektivt sätt, med möjligheten att inkludera de tidigare kvantmekaniska resultaten. En jämförelse mellan en simulering av ubiquitin med och utan polariserbarhet konstaterade att polariserbarheten verkar ha en dämpande effekt på orienteringen, åtminstone för begynnelsevillkoren som testades i denna studie. Vidare forskning krävs för att styrka modellen och utföra statistisk analys av många simuleringar med varierande begynnelsevillkor.

An assessment of the validity of idealizing a concrete diaphragm as rigid was performed through the modal analysis of three existing buildings. Modal analysis was performed both by physical experimentation and computational analysis. Experimental determination of the mode shapes shows that two of the three buildings’ diaphragms exhibited flexible behavior. The experimental results were compared to computational analysis results and were shown to be similar, confirming that that the two building diaphragms are not rigid. As a standard, diaphragms with aspect ratios less than three are permitted to be idealized as rigid per ASCE 7-05. To determine the effect of the rigid diaphragm idealization, the design forces and roof deflections for each building were determined from the computational model through a spectral analysis for both a model with rigid diaphragms and a model with semi-rigid diaphragms. It was found that the design seismic demands for the two buildings with flexible diaphragms were higher when modeled with semi-rigid diaphragms than with rigid diaphragms. The conclusion is made that idealizing a concrete diaphragm as rigid solely based on its aspect ratio may result in an unconservative estimate of the seismic demands on a building.

No / A vehicle that deviates laterally from its intended path of travel when the brakes are applied is considered to demonstrate ‘instability’ in the form of an unexpected and undesirable response to the driver input. Even where the magnitude of lateral displacement of the vehicle is small (i.e. ‘drift’ rather than ‘pull’) such a condition would be considered unacceptable by manufacturers and customers. Steering ‘drift’ during braking can be caused by several factors, some of which relate to vehicle design and others to external influences such as road conditions. The study presented here examines the causes and effects of steering drift during straight-line braking. A comparative analysis is made between two types of vehicle model: one built with rigid suspension components and the other with flexible components. In both the cases, the vehicle behaviour is simulated during braking in a straight line, and responses including lateral acceleration, yaw rate, and lateral displacement of the vehicle are predicted and analysed under fixed steering control. Suspension/steering geometry characteristics, namely toe steer and caster angle, have been studied to understand how the effect of variations in these parameters differs in models with rigid or flexible components drift during straight-line braking. Results from both vehicle models show that differences between rigid and flexible components can affect the predicted steering drift propensity. The differences between the two models have emphasized the importance of using flexible (compliant) components in vehicle handling simulations to achieve better correlation between prediction and experiment.

This thesis presents a research effort aimed at developing a stronger, lighter, and more economic shelter using rigid wall panels. Reported herein is insulation research, wall and roof panel design and testing, floor section modeling and strength calculations, and cost and weight calculations. Beginning stages focus on developing solid wall and roof panels using cold-formed steel corrugated sheathing and members, as well as polyurethane spray foam for insulation. This research includes calculating uniform load density, to determine the overall strength of the panel. The next stage focuses on the flexural strength of the wall and roof panels, as well as finalizing the floor design for the shelter. This includes determining maximum flexural strength required to meet the standards set by the project goal. Direct strength method determined the correct thickness of members to use based on the dimension selected for the design. All Phases incorporated different connection methods, with varied stud spacing, to determine the safest design for the new shelters. Previous research has shown that cold-formed steel corrugated sheathing performs better than thicker flat sheathing of various construction materials, with screw and spot weld connections. Full scale shear wall tests on this type of shear wall system have been conducted, and it was found that the corrugated sheathing had rigid board behavior before it failed in shear buckling in sheathing and sometimes simultaneously in screw connection failures. Another aspect of the research is on the insulation of the wall panels. Research was conducted on many different insulation options for the mobile facilities. Specifically, insulation made of lightweight material, is non-combustible, added rigidity to the structure, and has high thermal properties. Closed cell polyurethane spray foam was selected for full-scale testing in this research. Closed cell polyurethane adds extra rigidity, is lighter than common honeycomb insulation, and has a higher R-value. Several polyurethane foam companies were studied for this research, and promising products were identified. The research focuses on the impacts of the polyurethane foam to the structural performance of the wall panels. Both shear and 4-point bending tests were completed to investigate the strength and behavior of the cold-formed steel framed wall panels with polyurethane foam insulation. Comparing the cost and weight of the current shelter, and the new design is reported herein. The material studies, specimen details, and test results are reported in this thesis.

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Small proteins are difficult to study at high resolution with single-particle cryo-electron microscopy (cryo-EM). In general, sample properties such as large size (> 80 kDa), symmetry and rigidity are key to utilize this technology. To facilitate structural studies of small proteins as well, using cryo-EM, this project aims to incorporate a photo-inducible cross-link in a large and symmetric scaffold that is amenable for study, and covalently bind small proteins of interest to this scaffold. The scaffold in this project consists of rabbit muscle aldolase (157 kDa in tetrameric state) with an engineered affibody affinity protein (7 kDa) attached to the N-terminus of each aldolase monomer via a rigid helix fusion. The affibody-domain of the scaffold will be cross-linked to small proteins of structural interest, with a focus on a model target consisting of a second affibody with affinity for the affibody displayed on the aldolase scaffold. Photoconjugation of the affibody Zwt was performed to crosslink both the Fc of IgG and the anti-idiotypic affibody Z963, revealing that a methionine acceptor in the target is preferable but not necessary for UV crosslinking using BPA. Binding of affibodies rigidly displayed on of the scaffold to targets such as affibodies and antibody fragments was demonstrated , using surface plasmon resonance (SPR). / Att studera små protein vid hög upplösning med enpartikelsrekonstruktion i kryo-elektronmikroskopi (kryo-EM) är utmanande. Generellt så krävs stora (> 80 kDa), symmetriska och stabila protein för att använda sig av kryo-EM. Med målet att möjliggöra strukturbestämning och strukturella studier av små protein, så ska detta projekt föra in en foto-aktiverad korslänk i ett stort och symmetriskt bärarprotein. Bäraren består av aldolas från kaninmuskel (157 kDa som tetramer) med en affibody (7 kDa) kopplad till N-terminalen av varje aldolas-monomer via en rigidt fuserad helix. Affibody-domänen av bärarproteinet kan bilda korslänkar till små protein vars struktur sedan kan studeras. Fokus i projektet är ett modellprotein som består av en annan affibody som binder den affibody i bäraren. Fotokonjugering av affibodyn Zwt utfördes för att skapa korslänkar till både Fc av IgG, samt den anti-idiotypiska affibodyn Z963, vilket påvisade att en metionin-mottagare i målproteinet är fördelaktigt för UV korslänkning med BPA, men inte ett krav. Affinitet av affibodies i bärarproteinet till målprotein såsom andra affibodies och antikroppsfragment påvisades.