Sports related concussions result in 300,000 brain injuries in the United States each year. The purpose of this study was to utilize an in-helmet system that measures and records linear head accelerations to analyze head impacts from collegiate football. The Head Impact Telemetry (HIT) System is an in-helmet system with six spring mounted accelerometers and an antenna that transmits data via radio frequency to a sideline receiver and laptop computer system. The data reported by the HIT System includes the time of impact, location of impact, and linear acceleration resultant of the head center of gravity. The algorithm and in-helmet application for this system were validated in five series of tests. In particular, the validation emphasized that the HIT System measurements are of the player's head and not helmet accelerations as evidenced by the helmet acceleration being 16.6 (± 3.2) times greater than the peak head accelerations measured by the HIT System and dummy cg accelerometers. Using 130 head impacts in five different test configurations, the mean error in measuring peak linear acceleration was 0.01% (±18%). A total of 11,604 head impacts were recorded from the Virginia Tech football team throughout the 2003 and 2004 football seasons during 22 games and 62 practices from a total of 52 players. The acceleration data distribution was right skewed with a mean impact acceleration magnitude of 20.9 g and maximum value of 172.6 g. The HIC determined for each impact from a 15 millisecond time period was similarly distributed with the mean equal to 17.9, and the maximum equal to 969.6. A total of three impacts with three different players resulted in concussions. These impacts had peak linear accelerations of 55.7 g, 136.7 g, and 117.6 g with HIC values of 120.6, 518.4, and 355.6 respectively. Each of these hits was among the highest recorded for each respective player. Although the incidence of injury data is limited, this study presents an extremely large data set from human head impacts that provides valuable insight into the lower bounds of mild traumatic brain injuries. / Master of Science

Pappor till söner är oftast den närmsta manliga förbilden i söners liv, att vara förälder formar barnet och dess syn på sig själv och omvärlden. Den här studien undersöker hur pappor till söner ser på sin roll som man i samtiden och sin roll som pappa och förebild för sin son. Frågeställningen lyder: Hur ser pappor till söner på sin roll som manlig förebild för sin son/söner i förhållande till manskultur och maskuliniteter?  Det är en kvalitativ studie med hermeneutisk metod där fyra intervjupersoner deltog i semistrukturerade djupintervjuer. Avgränsningen är män som är födda på 1980-talet och är pappor till en eller flera söner. Deltagarna i studien berättar om hur de ser på sin roll som man och sin roll som pappa till nästa generations män. De är positiva till utvecklingen med jämställdhet och visar att de är medvetna om negativa maskuliniteter, de tar avstånd från machokulturen och hoppas på att vara bra förebilder för sina söner, att de ska få växa upp i en mer öppen och jämställd värld. Det arbete som har gjorts för jämställdheten i Sverige har hittills gett god effekt. Sverige har kommit längre i attityd till jämställdhet i jämförelse med ex USA som är mer konservativt lagda. Accelerationsprocesser påskyndar förändringarna på såväl mikro- som makronivå i samhället. Det hör ett modernt demokratiskt samhälle till att vara för jämställhet och en acceptans kring att vi är och gillar olika, men alla ska ha samma rättigheter, skyldigheter och möjligheter oavsett kön. / Fathers of sons is the closest male role model in the son's life and being a parent shapes the child and its view of itself and the world around it. This study examines how fathers of sons view their role as a man in the present and their role as a father and role model for their son. The question is: How do fathers of sons view their role as male role models for their son/sons concerning macho culture and masculinities? It is a qualitative study with a hermeneutic method where four interviewees participated in semi-structured interviews. The delimitation is men, born in the 1980s and are the fathers of one or more sons. The participants in the study talk about how they view their role as men and their role as father to the next generation of men. They are positive about the development of gender equality and show that they are aware of negative masculinities. They distance themselves from the macho culture and hope to be good role models for their sons, that they will grow up in a more open and equal world. The work that has been done for gender equality in Sweden has so far had a good effect. Sweden has come further in attitudes to gender equality in comparison with, for example, the USA, which is more conservative in attitudes towards gender equality.  Acceleration processes accelerate change at both the micro and macro levels in society. It belongs to modern democratic society, to be for equality and an acceptance that we are and like differently, that everyone should have the same rights and opportunities regardless of gender.

The methodology and analysis used to characterize the performance of a sabot/rod as it is subjected to lateral and axial loading during launch is presented. The methodology described incorporates the experimental and numerical portions of the evaluation. Three separate sabot/rod designs are evaluated for their performance in the launch tube and are compared with one another. The experimental portion of the research involved full-scale testing of two separate sabot/rod designs in a 120-mm launch tube that was slightly bent. When launched through the bent tube, the sabot/rod system was forced to negotiate lateral displacements at axial velocities of approximately 5400 fps. This combination of axial velocity and lateral displacement produced significant lateral loading on the sabot/rod system. A 2.3-MeV x-ray unit was used to determine the lateral displacement that occurred as the sabot/rod was forced through the bent tube. After the sabot/rod exited the launch tube, the sabot separation and rod straightness were recorded by four 150-keV x-ray units. The in-bore radiography experiments used x-ray shielding techniques to reduce x-ray scatter, and layered indexed film and intensifier screens to record the sabot/rod image. The processed film was computer scanned with a microdensitometer and was remapped on the computer to enhance the x-ray image. Results indicated rod lateral displacement accuracy to 0.007 in. Test results were used to benchmark the numerical analyses used to characterize the in-bore performance of each sabot/rod system studied. The numerical portion of the research involved three-dimensional modeling of the sabot/rod systems in three launch-tube environments: a perfectly straight launch tube, an existing accuracy tube, and the slightly bent tube used in the experimental program. Because of the good agreement between the experimental and numerical models, stress, strain, and displacement time histories were obtained from the numerical work and used to evaluate each of the three sabot/rod systems in three launch environments. A dynamic analysis was performed for each of nine separate models. Sliding surfaces, nonlinear constitutive relations, and multiple materials were used for each analysis. Results from both the experimental and numerical analyses are presented.

No description available.

The heating of solar chromospheric internetwork regions is investigated by means of the absorption of electromagnetic (EM) waves that originate from the photospheric black body radiation. It is studied in the framework of a plasma slab model. The absorption is provided by the electron-neutral collisions in which electrons oscillate in the EM wave field and electron-neutral collisions damp the EM wave. It is shown that for plausible physical parameters, the absorbed heating flux is between 20% and 45% of the chromospheric radiative loss flux requirement. Further, 1.5D particle-in-cell simulations of a hot, low density electron beam injected into magnetized, Maxwellian plasma were used to further explore the alternative non-gyrotropic beam driven EM emission mechanism, which was first studied in Ref.[83]. Variation of beam injection angle and background density gradient showed that the emission is caused by the perpendicular component of the beam injection current, whereas the parallel component only produces Langmuir waves, which play no role in the generation of EM waves in our mechanism. When the beam is injected perpendicularly to the background magnetic field, any electrostatic wave generation is turned off and a purely EM signal is left. Finally, a possible solution to the unexplained high intensity hard x-ray emission observable during solar flares was investigated via 3D particle-in-cell simulations. A beam of accelerated electrons was injected into a magnetised, Maxwellian, homogeneous and inhomogeneous background plasma. The electron distribution function was unstable to the beam-plasma instability and was shown to generate Langmuir waves, while relaxing to plateau formation. Three different background plasma density gradients were investigated. The strong gradient case produced the largest fraction of electrons beyond 15vth. Further, Langmuir wave power is shown to drift to smaller wavenumbers, as found in previous quasi-linear simulations.

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I föreliggande rapport har inventering och dynamiska kontroller utförts på 76 järnvägs­broar längs Botniabanan. Samtliga broar är byggda under perioden 1999 – 2009 och dimensionerade statiskt för tåglast BV2000. Broarna kan indelas i tre grupper; balk- och plattbroar, plattrambroar och samverkansbroar. Baserat på förenklade dynamiska analyser erhålls ett överskridande av den vertikala accelerationen för 75 % av alla plattrambroar och 40 % av alla balk- och plattbroar. Överskridande erhålls även för 4 av 9 samverkansbroar. Av totalt 76 analyserade broar motsvarar detta 41 broar som inte uppfyller kravet på sth 250 km/h. En sänkning till sth 200 km/h ger att 26 broar inte klarar de dynamiska kraven. Fyra broar har en nominell kritisk hastighet under 120 km/h. För plattrambroarna är accelerationsnivån i hög grad beroende på grundläggnings­förhållandena. Enligt tidigare BV Bro medräknades endast frekvenser upp till 30 Hz, vilket i kombination med antagande om oeftergivliga stöd ofta resulterade i att dynamiska kontroller inte utfördes för plattrambroar. Eftergivlighet hos grund­läggningen resulterar i vertikala stelkroppsmoder som i kombination med med­svängande massa av angränsande fyllning ger låga egenfrekvenser och därmed låga resonanshastigheter. För balkbroar beräknas mycket höga accelerationsnivåer då dessa är utformade med ändskärmar. Orsaken är att tåglasten inducerar en stötbelastning då den passerar änden på ändskärmen. Detta ger höga accelerationsnivåer även i angränsande spann, även utanför ett resonanstillstånd. Plattbroar ger ofta högre accelerationsnivåer jämfört med motsvarande balkbroar, beroende på att en lägre böjstyvhet ger lägre resonanshastighet. Detta förvärras kraftigt för plattbroar utformade med ändskärmar, vilket identifierats för t.ex. bro över Sidensjövägen. För samverkansbroarna beror de höga accelerationsnivåerna på en kombination av låg böjstyvhet och låg massa, vilket ger en låg resonanshastighet och hög accelerations­nivå. Problemet är störst för två fritt upplagda broar, Banafjälsån och Bryngeån. Förslag på fortsatta utredningar i syfte att påvisa att fler broar klarar de dynamiska kraven inkluderar mer avancerade analysmetoder i kombination med fältmätningar och kontrollerad excitering. Det bedöms i nuläget finnas stor potential att påvisa lägre accelerationsnivåer baserat på mindre konservativa antaganden om t.ex. dämpning och samverkan mellan bro och omgivande fyllning. / <p>QCV 20130529</p>

This thesis presents FAx86, a hardware/software full-system emulator of commodity computer systems using x86 processors. FAx86 is based upon the open-source IA-32 full-system simulator Bochs and is implemented over a single Virtex-5 FPGA. Our first prototype uses an embedded PowerPC to run the software portion of Bochs and off-loads the instruction decoding function to a low-cost hardware decoder since instruction decode was measured to be the most time consuming part of the software-only emulation. Instruction decoding for x86 architectures is non-trivial due to their variable length and instruction encoding format. The decoder requires only 3% of the total LUTs and 5% of the BRAMs of the FPGA's resources making the design feasible to replicate for many-core emulator implementations. FAx86 prototype boots Linux Debian version 2.6 and runs SPEC CPU 2006 benchmarks. FAx86 improves simulation performance over the default Bochs by 5 to 9\% depending on the workload.

This thesis presents FAx86, a hardware/software full-system emulator of commodity computer systems using x86 processors. FAx86 is based upon the open-source IA-32 full-system simulator Bochs and is implemented over a single Virtex-5 FPGA. Our first prototype uses an embedded PowerPC to run the software portion of Bochs and off-loads the instruction decoding function to a low-cost hardware decoder since instruction decode was measured to be the most time consuming part of the software-only emulation. Instruction decoding for x86 architectures is non-trivial due to their variable length and instruction encoding format. The decoder requires only 3% of the total LUTs and 5% of the BRAMs of the FPGA's resources making the design feasible to replicate for many-core emulator implementations. FAx86 prototype boots Linux Debian version 2.6 and runs SPEC CPU 2006 benchmarks. FAx86 improves simulation performance over the default Bochs by 5 to 9\% depending on the workload.

A simple Richardson iteration procedure converges slowly when applied to thick, diffusive problems with scattering ratios near unity. The current state of the art for overcoming this is to use a Krylov method with a diffusion preconditioner. However, the diffusion preconditioner must be tailored to the discretization of the transport operator to ensure effectiveness. We expand work from the bilinear discontinuous (BLD) finite element method (FEM) in two dimensions into a preconditioner applicable to all Discontinuous Galerkin FEMs in two and three dimensions. We demonstrate the effectiveness of our approach by applying it to the piecewise linear discontinuous (PWLD) FEM, which is notable for its flexibility with unstructured meshes. We employ a vertex-centered continuous FEM diffusion solution followed by local one-cell calculations to generate discontinuous solution corrections. Our goal is to achieve the same level of performance for PWLD and other methods, in two and three dimensions, as was previously achieved for BLD in two dimensions. We perform a Fourier analysis of this preconditioner applied to the PWLD FEM and we test the preconditioner on a variety of test problems. The preconditioned Richardson method is found to perform well in both ne and coarse mesh limits; however, it degrades for high-aspect ratio cells. These properties are typical for partially consistent diffusion synthetic acceleration (DSA) schemes, and in particular they are exactly the properties of the method that was previously developed for BLD in two dimensions. Thus, we have succeeded in our goal of generalizing the previous method to other Discontinuous Galerkin schemes. We also explore the effectiveness of our preconditioner when used within the GMRES iteration scheme. We find that with GMRES there is very little degradation for cells with high aspect ratios or for problems with strong heterogeneities. Thus we find that our preconditioned GMRES method is efficient and effective for all problems that we have tested. We have cast our diffusion operator entirely in terms of the single-cell matrices that are used by the discontinuous FEM transport method. This allows us to write our diffusion preconditioner without prior knowledge of the underlying FEM basis functions or cell shapes. As a result, a single software implementation of our preconditioner applies to a wide variety of transport options and there is no need to re-derive or re-implement a diffusion preconditioner when a new transport FEM is introduced.