Single-rate blanket application of fertilizer nitrogen (N) can result in an over or under application. Variable rate (VR) applications tailored to actual crop demands can improve N use efficiency in spatially variable soils. The objective of this study was to compare and improve relationships derived between corn canopy reflectance and corn N status acquired with two sensing platforms. Four fertilizer N rates were used, from deficient to excess, to create varying corn N status. Sensing and biophysical sampling was taken throughout the season for analysis and comparison to calculated vegetation indices (VIs). Results show strong relationships between VIs and corn N concentration and the strongest found using combined indices that incorporate the red-edge wavelength (720 nm). Relationships strengthened at latter growth stages. Results and models from this study demonstrate the utility of using remote sensing technologies to more accurately predict corn N status for eventual use in VR prescription development.

In the current study we developed an internal state variable (ISV) model based on the Bammann inelasticity internal state variable model (BIISV) to include damage, recrystallization, and texture development, which we then implemented into a mantle convection code, TERRA2D, to incorporate higher fidelity material behavior into mantle convection simulations. With experimental stress strain data found in the literature model constants for the BIISV model were determined for a number of geologic materials. The BIISV model was shown to be far superior to the steady state power law model currently used by the geologic community to capture the deformation of geologic materials. Once implemented and verified in TERRA2D the BIISV model revealed locations of hardened material that behaved like diverters in the cold thermal boundary layer that the power law model could never produce. These hardened regions could be a plausible reason for the current subduction zones present on the earth. We then altered the BIISV model equation to include the effects of damage, recrystallization, and texture development in order to model possible weakening mechanisms in the cold thermal boundary layer of the mantle. Inclusion of damage and recrystallization allowed the cold thermal boundary layer to mobilize and plunge downward into the hotter region below. Texture development increased the intensity of rotational flow within the hotter zone as cold boundary material plunged downward which aided in destabilizing the cold upper thermal boundary layer. The inclusion of an internal state variable model with damage, recrystallization, and texture development represents a significant advancement in handling deformational physics for mantle phenomena in a comprehensive, unified, and automatic manner.

There is a strong interest in the climate community to improve the ability to accurately predict future trends of climate variables. Recently, machine learning methods have proven their ability to contribute to more accurate predictions of historical data on a variety of climate variables. There is also a strong interest in using statistical downscaling to predict local station data from the output of multi-model ensembles. This project looks at using the machine learning algorithm XGBoost and evaluating its ability to accurately predict historical monthly precipitation, with a focus of applying this method to simulate future precipitation trends. / Thesis / Master of Science (MSc)

Arti cial neural networks (ANNs) are a powerful processing units inspired by the human brain. They can be used in many applications due to their pattern classi cation abilities, ability to model complex nonlinear input-output mappings, and their ability to adapt and learn. The relatively new Smooth Variable Structure Filter (SVSF) has recently been applied to the training of feedforward multilayered neural networks. It has shown to have good accuracy and a fast speed of convergence. In this thesis, an engine fault detection system using an ANN will be implemented. ANNs are used in engine fault detection due to the high-noise environment that engine operate in. Additionally the fault detection system must work while the engine is mounted in a vehicle, which provide additional sources of noise. The SVSF training method is evaluated and compared to other traditional training methods. Also di erent accelerometer types are compared to evaluate whether lower cost accelerometers can be used to keep the system cost down. The system is tested by inducing a missing spark fault, a fault that has a complex fault signature and is di cult to detect, especially in an engine with a high number of cylinders. / Thesis / Master of Applied Science (MASc)

Variable-density thinning (VDT) is a management option designed to increase structural heterogeneity in second-growth conifer stands. This study examined subcanopy tree growth response to two variations of VDT. At the Forest Ecosystem Study in western Washington, thinning intensity was found to have a significant effect on height growth of Douglasir (Pseudotsuga menziesii (Mirb.) Franco) seedlings which established following the thinning. At the Olympic Habitat Development Study in western Washington, basal area growth response was examined for residual midcanopy western hemlock (Tsuga heterophylla (Raf.) Sarg.) and western redcedar (Thuja plicata ex. D. Don). Both species retained the ability to respond to thinning. The results of this study suggest that non-uniform thinning practices, like VDT, can lead to variation in growth response of residual subcanopy trees and new regeneration. This may accelerate the development of more structurally diverse forests than traditional management practices.

In this investigation, four coatings were tested for their ability to increase the wear life of A390 aluminum primary clutch sheaves used in continuously variable transmission (CVT). The coatings tested were: hard chrome, electroless nickel metal, hard coat anodizing and composite ceramic coating. The primary clutch sheave material is a die-cast A390 aluminum. A wear test stand was developed to duplicate wear found on CVTs currently in use. The wear was evaluated using four methods. First, the change in shift characteristics of the CVT while running on the wear test stand, second a change in performance using an ATV and chassis dynamometer, third the amount of material lost, through wear, was measured using a profilometer, and finally a scanning electron microscope which was used to identify the dominate mechanism of wear in the sheave material. All of the tests showed the hard chrome coating to have the lowest wear rates and the best wear characteristics. The electroless nickel metal coating did improve the wear life of the CVT but had very high variation. The hard coat anodized and ceramic composite coatings were eliminated early in testing because of poor performance.

Construction is increasing due to increased demand and degradation of existing infrastructure. This construction often results in a reduced number of traffic lanes or lane width during construction, which often creates queue at the entrance to work zones. Variable Advisory Speed Systems (VASS) provide drivers with advanced warning regarding traffic speeds downstream to help them make better decisions in advance of problems that may exist downstream. The purpose of this study was to evaluate the effectiveness of a VASS at mitigating queues in work zone entrances during peak hour conditions. It was anticipated that by implementing a VASS queues would be reduced and vehicle flow increased in work zone areas. Three objectives of this study were: (1) research VASS systems that are available to be tested, (2) select and deploy a VASS in Utah at a long-term work zone, and (3) perform a statistical analysis on traffic flow characteristic data to evaluate the effectiveness of the VASS on queue mitigation. A literature review on the use of VASS for work zones returned minimal studies on advisory speeds in work zones. Most of the advanced speed notification systems, found during the literature review, used variable speed limit (VSL) applications. A VASS was selected and deployed at the northbound approach to the I-15 Beck St. widening project in North Salt Lake City. In this study the VASS consisted of five sensors and two variable message signs (VMSs). To determine if the system was effective at reducing queue the speed data were analyzed in detail to come to statistical conclusions. The collected data shows that the VASS investigated was effective on weekends during evening peak hours when there was a slow down. No consistent significance was seen on week days during the evening peak. There was no statistical difference between before and after speed data on any day of the week when there was no slow down. This study is valuable because it is unique in studying an advisory speed using VMSs and other ITS technology. This study recommends that further studies be conducted without a movable median barrier system, as was used in this construction project, to evaluate further about the effectiveness of VASSs. It is recommended that, if a VASS is considered, studies be done to see whether queues are expected to form at the work zone entrance, as VASSs will not be effective if queues do not form.

Research in developing a Positively Engaged Continuously Variable Transmission (PECVT) has been underway at Brigham Young University for some time. The inherent problems associated with embodiments of this type of transmission, namely the Non-Integer Tooth Problem (NITP), have been identified. This research is focused on the development of a Positively Engaged Piecewise Continuous Transmission (PEPCT), which is a subset of the PECVT. This document describes the hypothesis and analysis of using non-circular gearsets to overcome the NITP. This proposed solution enables a varying angular output from a constant angular input. In this research two analytical methods were evaluated based on their theory, mathematics and simulated results. Haupt's concept is shown to have discrepancies between the theorized and mathematical results which produce a gearset that has velocity spikes in its output. The second method, proposed by Danieli, describes the behavior on an infinitesimal level and the theorized results match up with the mathematical result. As a result of the analysis, Danieli's method is declared to produce a varying output from a constant input. The method requires only the definition of an input function that defines the shape of the pitch line similar to the pitch circle for circular gears. Using this function an infinitesimal approach is used to describe the interaction of consecutive contact points on the tooth profiles. This interaction takes into consideration adapted principles that are derived from the Fundamental Law of Gearing and the Law of Conjugate Action. With these principles defined it is possible to design gearsets that are capable of producing a varying angular output from a constant angular input. With the validation of the second method, and the principles defined by which it is governed, the proposed gearset is achievable allowing a PEPCT to be conceived. The proposed transmission utilizes the non-circular gearset to accelerate a secondary shaft to the next desired ratio while maintaining constant engagement. This concept is then analyzed and recommendations are made for the development of a Positively Engaged Continuously Variable Transmission.

Hardware-in-the-loop (HIL) modeling is a powerful way of modeling complicated systems. However, some hardware is expensive to use in terms of time or mechanical wear. In cases like these, optimizing using the hardware can be prohibitively expensive because of the number of calls to the hardware that are needed. Variable fidelity optimization can help overcome these problems. Variable fidelity optimization uses less expensive surrogates to optimize an expensive system while calling it fewer times. The surrogates are usually created from performing a design of experiments on the expensive model and fitting a surface to the results. However, some systems are too expensive to create a surrogate from. One such case is that of a flapping flight model. In this thesis, a technique for variable fidelity optimization of HIL has been created that optimizes a system while calling it as few times as possible. This technique is referred to as an intelligent DOE. This intelligent DOE was tested using simple models of various dimension. It was then used to find a flapping wing trajectory that maximizes lift. Through testing, the intelligent DOE was shown to be able to optimize expensive systems with fewer calls than traditional variable fidelity optimization would have needed. Savings as high as 97% were recorded. It was noted that as the number of design variables increased, the intelligent DOE became more effective by comparison because the number of calls needed by a traditional DOE based variable fidelity optimization increased faster than linearly, where the number of hardware calls for the intelligent increased linearly.

Research has suggested that although mathematics is a universal language, the notation, algorithms, and language in which it is taught varies from country to country. The literature has addressed the challenges associated with understanding the language of mathematics in English. Variable is a topic of mathematics where the literature has documented students' difficulty understanding the language of mathematics. Part of that difficulty is attributed to the fact that mathematics and English each have their own register and at times the differences in these registers conflict. This study examined the introduction and use of variable in the middle school textbooks of three English speaking countries and three Spanish speaking countries. The results of this study are that textbooks rarely make any attempt to use bridging language, and do not explain to students how they are using variable when they use it. The results of this study also show that the language used to talk about variable is similar English (Spanish) speaking countries.