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Automobile accident reconstruction has been facilitated by the development of computer based modules to allow evaluation of evidence gathered at the accident scenes. Although the computer modules are based in fundamental physical laws, an understanding of these laws by the user is required for proper application of the computer model in a given accident scenario. Vehicle collision analysis techniques generally separate the collision into three phases: pre-impact, impact, and post impact. The intent of the research is to provide a generalized model to reconstruct two dimensional impact problems in the area of accident reconstruction. There are currently two modeling techniques used to reconstruct the impact phase: the first technique relying exclusively on impulse-momentum theory coupled with friction and restitution, while the second method combines impulse momentum with a relationship between crush geometry and energy loss. Because each method requires very different inputs, the literature would have us believe that both methods are different. We will show that both methods are derived using the same fundamental physical principles and for any given accident scenario, both methods will provide identical results. Each method will be presented in the form of a MathCAD spread sheet that will allow the user to reconstruct a wide variety of accidents controlling just a few parameters (i.e. mass, rotational inertia, angle of approach, etc...). Both methods will provide step by step graphical representation to assure a solid approach to physical fundamentals. The governing equations to the generalized energy approach will be non-dimensionalized and used to define all of the changes in energy (i.e. also referred to as an impulse in power) as a function of a characteristic velocity. Finally, different methods to consistently determine the direction of the force will be presented when additional information from the accident scene is provided.

The Tangential Momentum Accommodation Coefficient (TMAC) is used to improve the accuracy of fluid flow calculations in the slip flow regime. Under such conditions (indicated by Knudsen number greater than 0.001), the continuum assumption that a fluid velocity at a solid surface is equal to the surface velocity is inaccurate because relatively significant fluid "slip" occurs at the surface. Prior work has not led to a method to quickly estimate a value for TMAC - it is frequently assumed. In this work, Molecular Dynamics techniques are used to study the impacts of individual gas atoms upon solid surfaces to understand how approach velocity, crystal geometry and interatomic forces affect the scattering of the gas atoms, specifically from the perspective of tangential momentum. It is a logical step in the development of a comprehensive technique to estimate total coefficient values to be used by those investigating flows in micro- and nano-channels or on orbit spacecraft where slip flow occurs. TMAC can also help analysis in transitional or free molecular regimes of flow. The gas - solid impacts were modeled using Lennard Jones potentials. Solid surfaces were modeled with approximately 3 atoms wide by 3 atoms deep by 40 or more atoms long. The crystal surface was modeled as a Face Centered Cubic (100). The gas was modeled as individual free gas atoms. Gas approach angles were varied from 10 degrees to 70 degrees from normal. Gas speed was either specified directly or by way of a ratio relationship with the Lennard-Jones energy potential (Energy Ratio). In order to adequately model the trajectories and maintain conservation of energy, very small time steps (on the order of 0.0005 [tau] , where [tau] is the natural time unit) were used. For each impact the initial and final tangential momenta were determined and after a series of many impacts, a value of TMAC was calculated for those conditions. The modeling was validated with available experimental data for He gas atoms at 1770 m/s impacting Cu over angles ranging from 10° to 70°. The model agreed within 3% of the experimental values and correctly predicted that the coefficient changes with angle of approach. Molecular Dynamics results estimate TMAC values from a high of 1.2 to a low of 0.25, generally estimating a higher coefficient at the smaller angles. TMAC values above 1.0 indicate backscattering, which has been experimentally observed in numerous instances. The ratio of final to initial momenta, when plotted for a given sequence of gas atoms spaced across a lattice cycle typically follows a discontinuous curve, with continuous portions indicating forward and back scattering and discontinuous portions indicating multiple bounces. Increasing the Energy Ratio above a value of 5 tends to decrease the coefficient at all angles. Adsorbed layers atop a surface influence the coefficient similar to their Energy Ratio. The results provide encouragement to develop the model further, so as to be able in the future to evaluate TMAC for gas flows with Maxwell temperature distributions involving numerous impact angles simultaneously.

Sammanfattning Titel: Effektiva marknadshypotesen EMH, Momentum - Investeringsstrategi Nivå: Examensarbete på grundnivå (kandidatexamen) i ämnet företagsekonomi Författare: Andreas Andersson och Alexander Andersson Handledare: Peter Lindberg Datum: 2023 - Juni Syfte: Syftet med denna studie är att testa den effektiva marknadshypotesen genom investeringsstrategin momentum.  Metod: Studien har en deduktiv ansats där en kvantitativ metod har använts för att samla in sekundärdata från olika databaser. Olika marknader har analyserats genom att skapa olika momentumportföljer som bygger på momentum som är en investeringsstrategi för att testa hur effektiva dessa marknader är.  Resultat & Slutsats: Studiens resultat visar att olika marknader är olika effektiva. Momentumstrategi 1 gav inte en överavkastning och momentumstrategi 2 gav en överavkastning på samtliga portföljer.  Uppsatsens bidrag: Studien bidrar med kunskap om olika marknaders effektivitet. Den ger även kunskap om hur momentum fungerar som investeringsstrategi på olika marknader och tillgångar.  Förslag till fortsatt forskning: Förslag på vidare forskning är att undersöka andra marknader och använda momentum som investeringsstrategi på andra tillgångar samt att använda sig av kortare momentumsignaler.  Nyckelord: Effektiva marknadshypotesen, Anomalier, Investeringsstrategi, Momentum, Momentumstrategi, Momentumportfölj, Jämförelseindex, Buy and Hold Strategi.

No / A discrete particle model is described which simulates bedload transport over a flat bed of a unimodal mixed-sized distribution of particles. Simple physical rules are applied to large numbers of discrete sediment grains moving within a unidirectional flow. The modelling assumptions and main algorithms of the bedload transport model are presented and discussed. Sediment particles are represented by smooth spheres, which move under the drag forces of a simulated fluid flow. Bedload mass-transport rates calculated by the model exhibit a low sensitivity to chosen model parameters. Comparisons of the calculated mass-transport rates with well-established empirical relationships are good, strongly suggesting that the discrete particle model has captured the essential elements of the system physics. This performance provides strong justification for future interrogation of the model to investigate details of the small-scale constituent processes which have hitherto been outside the reach of previous experimental and modelling investigations.

<p>The notion of momentum has received significant attention from sports psychologists. Recently, however, some researchers have introduced it to educational contexts and developed a psychological momentum perspective toward academic motivations. Different from other motivation theories, the psychological momentum theory mainly builds on Newtonian physics. It stresses the analogy between physical concepts (mass, inertia, and momentum) and psychological processes. While such a background brings several novel and appealing insights into academic motivations, as the theory is still new to the field, more validation work, such as those exploring its convergence and divergence with other established theories, is needed. Using self-determination theory as a complementary theory, the current study explored the convergence between the two theories by examining the association between self-determined motivations and two states of academic inertia (i.e., low-momentum state inertia [LMSI] and high momentum state inertia [HMSI]). The study also examined the two theories’ divergence by investigating how the two states of inertia predict academic engagement over and above self-determined motivations. </p> <p>Two hundred and six undergraduate students from a Midwestern university participated in this study. Regarding convergence, results provided mixed support for the hypothesis. No significant association was obtained between HMSI and all motivations; however, LMSI was negatively associated with intrinsic motivation and the relatively autonomy index but positively associated with amotivation (all to a weak-to-moderate extent). Regarding divergence, results demonstrated that inertia explained a moderate-yet-meaningful amount of variation in academic engagement, even after self-determined motivations are controlled for. Taken together, the results suggested the promise of PMT as a motivation theory. Based on the findings, implications and limitations of the study were further discussed.<b><br> </b></p>

Impinging oxygen jets are widely used in steelmaking industries. The momentum transfer from the gas to liquid and resulting instability affect the overall productivity and operational stability. The purpose of this research is to understand the surface deformation, its stability and momentum transfer from the gas to the liquid. Video imaging and Particle Image Velocimetry were used along with water modelling techniques. Surface deformations mainly followed the dimensionless relationship of previous researchers. The surface instability was interpreted with Blowing number and Kelvin-Helmholtz instability. Spatial and time oscillation behaviour were analyzed with Power Spectral Density analysis. A new mathematical model with the full stress boundary condition at the surface was developed. The technique combines the Cartesian Cut Cell and Volume of Fluid method and the surface boundary was modelled a a pressure boundary. The numerical code was tested with the Broken Dam and wave instability problems. Both showed good agreement with the reported physical phenomena. Numerical tests of impinging jets showed similar surface depression depth with the water model experiments. The model was compared with other models. The liquid momentum level was higher as the gas fiowrate increased and the effects of physical property changes on surface instability and momentum transfer efficiency were investigated with the mathematical model. With observations from the numerical test, momentum transfer mechanisms were proposed. Simulations of momentum transfer at industrial flow rates were also carried out. / Thesis / Doctor of Philosophy (PhD)

This thesis investigates the long-standing Abraham-Minkowski controversy concerning the momentum of light inside a dielectric medium. A revealing connection to the optical He-McKellar-Wilkens (HMW) phase is found upon studying the Langrangian describing the classical laser-atom interaction. This connection is further highlighted by moving into a semi-classical model in which the phase arises as a result of the transformation between the Abraham and Minkowski Hamiltonians. The HMW along with the Aharonov-Casher phases are found to be both dynamic and geometric depending on the representation. It is shown that an optical version of the HMW phase is acquired by a dipole moving in a laser beam, and I propose several interferometric schemes in order to observe the optical HMW effect. Finally, by moving into a cavity system, it is possible to account for the back action of the atoms on the light which changes the electromagnetic mode structure. This increase in model sophistication grants an alternative vantage from which to interpret the Abraham-Minkowski problem. / Thesis / Doctor of Philosophy (PhD)

Twisted particles carry Orbital Angular Momentum (OAM), an important property utilized to encode quantum information. The OAM of twisted photons can be trans- ferred onto condensed matter systems in the form of twisted excitons. Numerical solutions of the time-dependent Schr ̈odinger equation for a 3-arm molecular chain are used to demonstrate the manipulation of twisted excitons via an external magnetic field. We present the first design for an OAM transistor in a quasi-1D system that can be used to control the flow of OAM using the magnetic field. The underlying mechanism is the interaction between OAM and the magnetic field which leads to a orbit-resolved Bloch oscillation (ORBO). We present the semi-classical equations of motion for this phenomenon in a one-dimensional system. Unlike classical Bloch oscil- lation, an important effect in ultrafast electron dynamics, the magnet driven ORBO is not limited by electrical breakdown and can easily be observed in natural solids.