Browsing by Subject "magnetics"

Now showing 1 - 3 of 3
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    From Compass to Drone: The Evolving Role of Magnetics in Mapping the Geology and Ore Deposits Of the Lake Superior Region: 1830-2022
    (Minnesota Geological Survey, 2022) Hinze, William J
    The Lake Superior region, the “Birthplace of North American Precambrian Geology,” is noted for its world-class mineral resources, especially its native copper and iron ore deposits, and its classic bedrock of Archean and Proterozoic orogenic belts and the exposures of rocks of the Midcontinent Rift System. The magnetic method of mapping the region’s ore deposits and bedrock geology has been used for nearly two centuries because of limitations in the exposure of the Precambrian bedrock in the region. For the first century magnetic mapping was directed primarily at the identification of regions favorable for iron and copper ore deposits using simple magnetic needle instrumentation. Initially instrumentation was limited to the use of the dial (sun) compass and used mainly for exploration of hard, magnetite-rich iron ore deposits. With the introduction of the dip needle, a counterbalanced magnetic needle oscillating vertically in the magnetic meridian, to the Lake Superior region likely in 1865 by T.B. Brooks, magnetic mapping was no longer restricted to the difficult to interpret magnetic field angular variations.
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    Gravity and Magnetic Studies in Carver County and Adjacent Areas, Southeastern Minnesota
    (Minnesota Geological Survey, 2009) Chandler, V.W.
    This report summarizes the gravity and magnetic studies that were done as part of the Carver County Geologic Atlas (CGA) study. This work compliments the bedrock geology component of the project, and it has three objectives, as described below: 1. The first objective is to create gravity and magnetic grid images to assist in compiling the bedrock map sheet for the CGA. 2. The second objective was to use gravity and magnetic model studies to help create geologic cross sections that are to accompany the bedrock geology map sheet. 3. The third objective was to apply a semi-automated magnetic interpretation scheme called Euler Deconvolution (Reid and others, 1990), which estimates the location and depth of magnetic anomaly sources.
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    Microwave Interaction with Magnons for Nonlinear Devices
    (2021-09) Venugopal, Aneesh
    Perturbations of the magnetic order, known as spin-waves or magnons, within a ferri- or ferromagnet can exhibit nonlinear properties. The nonlinearity of the magnons can be exploited for information processing applications and for understanding fundamental aspects of nonlinear processes. When using insulators such as Yittrium iron garnet (YIG), various functionalities such as signal processing can be realized in the absence of Ohmic losses. Moreover, the small wavelengths of spin waves can also help with the miniaturization of devices. Such advantages have made magnons attractive for a wide variety of applications ranging from communications to logic circuits. Although magnons have been studied in the past, precise understanding and the details of various nonlinear processes are still largely lacking. Device design is often based on trial-and-error approaches with regard to magnonic properties. Efficient and robust design, however, requires a deterministic understanding of material behavior. Moreover, given the long experimental cycles involved in device design, the ability to predict properties accurately is crucial. In this thesis, I will discuss the development of a high-speed CUDA-GPU (graphics processing unit)-based parallel platform to study magnons that are created by microwave excitation of magnetic materials. The goal is twofold: to enable a better understanding of nonlinear properties and to improve device design capabilities. Device characteristics of magnet-based frequency-selective limiters (FSLs) used for microwave signal processing are studied using simulations involving rigorous calculations of dipolar-, exchange-, and thermal-magnetic fields. These studies offer beneficial insights into the role of physical processes like higher-order scattering on the device behavior. A key requirement in many applications is the dynamic control of the threshold field -the minimum microwave field needed to turn on the nonlinear behavior in a magnetic sample. The ability to dynamically vary the threshold field using an additional microwave is explained analytically and demonstrated using simulations. The importance of magnon-phase in the nonlinear processes is also explicitly demonstrated. Despite the crucial role of magnon-phase in nonlinear physics, few studies focus on the impacts of magnonic phase-noise. I have developed an analytical theory to understand the impacts of magnon phase noise. The conclusions of the theory are verified using micromagnetic simulations.Magnetic recording comprises highly nonlinear processes that, unlike perturbative effects, involve the reversal of magnetization. Using micromagnetic simulations, I designed a high-density magnetic recording scheme employing state-of-the-art heat-assisted and bit-patterned techniques. Even after considering noise factors such as jitter and track misregistration, the design provides an extremely high density of 16 Terabits per square centimeters (Tbpsi).