There are many traffic simulation modeling packages in existence, some of which are designed specifically for work zone analysis. These packages include, for example QUEWZ, Quick Zone, CORSIM and VISSIM. This research evaluates the capabilities of these simulation packages to determine whether or not these packages produce reasonable impact estimates. The research concludes with a set of recommendations to assist transportation professionals in selecting the most appropriate simulation package for a particular work zone project.

Friction stir welding (FSW) is a solid-state joining process that offers advantages over traditional fusion welding. The amount of heat generated during a FSW process greatly influences the final properties of the weld. The heat is generated through two main mechanisms: friction and plastic deformation, with friction being the larger contributor in a FSW process. There is a need to develop better predictive models of the heat generation and heat transfer in FSW. Almost all models seen in the literature validate temperature predictions on only one side of the tool/workpiece interface, thus ignoring possible inaccuracy that comes from incorrect partitioning of heat generated by friction. This work seeks to model and validate both sides of the interface by matching experimental results for both the plunge and steady state phases of FSW for AA 6061-T6. Proper model validation allowed for a study of the sensitivity of the model predictions to changes in the friction coefficient and heat transfer coefficient at the tool/workpiece interface. Most models in the literature use the Coulomb friction law with a fixed friction coefficient, even though the Norton law better incorporates local material behavior. As such, for the plunge phase of FSW, a method for achieving a time dependent friction coefficient was developed and employed to match experimental temperatures, using Norton's viscoplastic friction law. A friction coefficient of 0.65 was used at the start of the plunge phase, decreasing to 0.08 during the steady state phase. This decrease in magnitude from plunge to steady state is similar to the decrease of the Coulomb friction coefficient calculated by Meyghani et al in a 2017 study. Tuning the models resulted in temperature predictions that differed from experimental measurements by no more than 1.5 percent for the non-steady state plunge and by no more than 9 percent for the steady state simulation. For both models, changes in the heat transfer coefficient had a large effect on tool temperature and very little effect on workpiece temperatures. Increasing the friction coefficient led to a proportional increase in temperature for both the tool and workpiece.

This report describes the development process of the Deutsche Bank Intro to Controls instructional training tool. This course utilizes a multi-faceted, blended approach, including web-based training, simulation, and instructor-led training components to teach complex banking operations. The report includes a literature review describing instructional theories, and strategies concerning the use of a blended approach in the training of complex systems and operations. The report also includes a description of the formative evaluation process and results. These results demonstrated a positive response to the content and instructional strategies employed in the training, as well as the need for future research to evaluate long-term effects of the training. Finally, the report contains a critique of the project, discussing its strengths, its weaknesses, and opportunities for future training projects.

When used in a wireless mesh network, TCP has shortcomings in the areas of throughput and fairness among traffic flows. Several methods have been proposed to deal with TCP's weakness in a wireless mesh, but most have been evaluated with simulations rather than experimentally. We evaluate several major enhancements to TCP – pacing, conservative windows, and delayed ACKs – to determine whether they improve performance or fairness in a mesh network operating in the BYU Computer Science building. We also draw conclusions about the effectiveness of wireless network simulators based on the accuracy of reported simulation results.

Successful integration of simulations within the Network-Based Defence (NBD), specifically use of simulations within Command and Control (C2) environments, enforces a number of requirements. Simulations must be reliable and be able to respond in a timely manner. Otherwise the commander will have no confidence in using simulation as a tool. An important aspect of these requirements is the provision of fault-tolerant simulations in which failures are detected and resolved in a consistent manner. Given the distributed nature of many military simulations systems, services for fault-tolerance in distributed simulations are desirable. The main architecture for distributed simulations within the military domain, the High Level Architecture (HLA), does not provide support for development of fault-tolerant simulations. A common approach for fault-tolerance in distributed systems is check-pointing. In this approach, states of the system are persistently stored through-out its operation. In case a failure occurs, the system is restored using a previously saved state. Given the abovementioned shortcomings of the HLA standard this thesis explores development of fault-tolerant mechanisms in the context of the HLA. More specifically, the design, implementation and evaluation of fault-tolerance mechanisms, based on check-pointing, are described and discussed. / QC 20101111

Scalable and efficient numerical simulations continue to gain importance, as computation is firmly established tool of discovery, together with theory and experiment. Meanwhile, the performance of computing hardware grows with increasing heterogeneous hardware, enabling simulations of ever more complex models. However, efficiently implementing scalable codes on heterogeneous, distributed hardware systems becomes the bottleneck. This bottleneck can be alleviated by intermediate software layers that provide higher-level abstractions closer to the problem domain, hence allowing the computational scientist to focus on the simulation. Here, we present OpenFPM, an open and scalable framework that provides an abstraction layer for numerical simulations using particles and/or meshes. OpenFPM provides transparent and scalable infrastructure for shared-memory and distributed-memory implementations of particles-only and hybrid particle-mesh simulations of both discrete and continuous models, as well as non-simulation codes. This infrastructure is complemented with frequently used numerical routines, as well as interfaces to third-party libraries. This thesis will present the architecture and design of OpenFPM, detail the underlying abstractions, and benchmark the framework in applications ranging from Smoothed-Particle Hydrodynamics (SPH) to Molecular Dynamics (MD), Discrete Element Methods (DEM), Vortex Methods, stencil codes, high-dimensional Monte Carlo sampling (CMA-ES), and Reaction-Diffusion solvers, comparing it to the current state of the art and existing software frameworks.

While direct measurements of energetic demands are nearly impossible to collect on large cetaceans, comprehensive bioenergetic models can give insights on such parameters by combining physiological and ecological knowledge. This model was developed to estimate necessary food intake of gray whales, Eschrichtius robustus, of the Eastern North Pacific stock. Field Metabolic Rates (FMR) for gray whales were first estimated based on various assumptions (e.g. volumetric representation of gray whales, extent of their feeding season, and blubber depth distribution) using morphometric data, energetic costs, and food assimilation according to age and gender specific requirements. Food intake rates for gray whales of varying maturity and gender were then estimated based on FMR and caloric value of prey and compared to food intake rates of previous studies. Monte Carlo simulations and sensitivity analysis were performed to assess the model's predictions compared to observed field data from previous studies. Predicted average food intakes for adult male, pregnant/ lactating female, and immature whales were 475 ± 300, 525 ± 300 and 600 ± 300 kg d-1, respectively. Estimated blubber depths resulting from these food intakes were comparable to field data obtained from whaling data. Sensitivity analysis indicated food intake, from all parameters, as having the highest impact on the percent change in ending mass from a simulation. These food intake estimates are similar to those found in a previous study and fall within the range of food intake per body mass observed in other species of cetaceans. Though thermoregulation can be a factor in some cetaceans, it appears not to be an additional cost for gray whales as the present model's predicted lower critical temperatures for the whales (TLC) were below ambient temperatures. With temperatures increasing in the Bering Sea, the main prey of gray whales, ampeliscid amphipods, could be adversely affected, possibly resulting in increased food shortages leading to a surge in gray whale strandings.

The aim of this dissertation is to investigate self-assembled structures and the phase diagram of amphiphilic molecules of diverse geometric shapes using a number of different computer simulation methods. The semi-realistic coarse-grained model, used extensively for simulation of polymers and surfactant molecules, is adopted in an off-lattice approach to study how the geometric structure of amphiphiles affects the aggregation properties. The results of simulations show that the model system behavior is consistent with theoretical predictions, experiments and lattice simulation models. We demonstrate that by modifying the geometry of the molecules, self-assembled aggregates are altered in a way close to theoretical predictions. In several two and three dimensional off-lattice Brownian Dynamics simulations, the influence of the shape of the amphiphilic molecules on the size and form of the aggregates is studied systematically. Model phospholipid molecules, with two hydrophobic chains connected to one hydrophilic head group, are simulated and the formation of stable bilayers is observed. In addition, (practically very important) mixtures of amphiphiles with diverse structures are studied under different mixing ratios and molecular structures. We find that in several systems, with Poisson distributed chain lengths, the effect on the aggregation distribution is negligible compared to that of the pure amphiphilic system with the mean length of the Poisson distribution. The phase diagrams of different amphiphilic molecular structures are investigated in separate simulations by employing the Gibbs Ensemble Monte Carlo method with an implemented configurational-bias technique. The computer simulations of the above mentioned amphiphilic systems are done in an area where physics, biology and chemistry are closely connected and advances in applications require the use of new theoretical, experimental and simulation methods for a better understanding of their self-assembling properties. Obtained simulation results demonstrate the connection between the structure of amphiphilic molecules and the properties of their thermodynamically stable aggregates and thus build a foundation for many applications of the remarkable phenomena of amphiphilic self-assembly in the area of nanotechnology.

This research considers two modes of training Army infantry officers in initial training to conduct a platoon live fire exercise. Leaders from groups that were training with the current classroom training methods were compared to leaders from groups whose training was augmented with a PC based training system known as the Rapid Decision Trainer (RDT). The RDT was developed by the US Army Research Development and Engineering Command for the purpose of aiding in the training of tactical decision making and troop leading procedures of officers in the initial levels of training to become rifle platoon leaders. The RDT allows the leader in training to run through platoon level operations prior to live execution in a simulated combat environment. The focus of the system is on leadership tasks and decision making in areas such as unit movement, internal unit communication and contingency planning, and other dismounted infantry operations. Over the past year, some Infantry Officer Basic Course platoons at Ft. Benning have used the RDT in an experimental manner. Anecdotal evidence suggests that the system is beneficial in training IOBC officers. The Army Research Institute (ARI) conducted a preliminary evaluation of the RDT in March 2005 (Beal 2005). However, no quantitative measures were used in the evaluation of the RDT, only subjective evaluations of the users. Additionally, there were no formal evaluations by the training cadre, only the users themselves. This experiment continues the work of ARI and uses qualitative and quantitative data from both users and the evaluating cadre. In this experiment, the effectiveness of the RDT was evaluated through measuring leader behaviors and personal preferences. Three measurement approaches were used; (1) quantitative performance measures of leader actions, (2) qualitative situational awareness and evaluations of inclusion in the non leader players, and (3) a qualitative evaluation of the system's usability and effectiveness by system users. Analysis reveals statistically significant findings that challenge the current norms.

We present a model of laser-solid interactions in silicon based on an empirical potential developed under conditions of strong electronic excitations. The parameters of the interatomic potential depends on the temperature of the electronic subsystem Te, which is directly related to the density of the electron-hole pairs and hence the number of broken bonds. We analyze the dynamics of this potential as a function of electronic temperature Te and lattice temperature Tion. The potential predicts phonon spectra in good agreement with finite-temperature densityfunctional theory, including the lattice instability induced by the high electronic excitations. For 25fs pulse, a wide range of fluence values is simulated resulting in heterogeneous melting, homogenous melting, and ablation. The results presented demonstrate that phase transitions can usually be described by ordinary thermal processes even when the electronic temperature Te is much greater than the lattice temperature TL during the transition. However, the evolution of the system and details of the phase transitions depend strongly on Te and corresponding density of broken bonds. For high enough laser fluence, homogeneous melting is followed by rapid expansion of the superheated liquid and ablation. Rapid expansion of the superheated liquid occurs partly due to the high pressures generated by a high density of broken bonds. As a result, the system is readily driven into the liquid-vapor coexistence region, which initiates phase explosion. These results strongly indicates that phase explosion, generally thought of as an ordinary thermal process, can occur even under strong non-equilibrium conditions when Te > > TL. In summary, we present a detailed investigation of laser-solid interactions for femtosecond laser pulses that yield strong far-from-equilibrium conditions.