Browsing by Subject "aggregate"

Now showing 1 - 5 of 5
  • Thumbnail Image
    Item
    Aggregate Resources Inventory of the Seven-County Metropolitan Area, Minnesota, St. Paul
    (Minnesota Geological Survey, 1982) Meyer, G.N.; Jirsa, M.A.
    Report and maps prepared for the Twin Cities Metropolitan Council detailing aggregate resources in the seven-county metropolitan area.
  • Thumbnail Image
    Item
    Characterization Techniques for Aggregated Nanomaterials in Biological and Environmental Systems
    (2016-06) Jeon, Seongho
    Nanoparticles, which are defined as objects with characteristic lengths in the 10^-9 – 10^-7 m (nanoscale) size range, are used with increasing frequency in a wide of applications, leading to increases in nanomaterial interactions with biological and environmental systems. There is therefore considerable interest in studying the influence nanomaterials can have when inside the human body or dispersed in the ambient environment. However, nanoparticles persist as homo aggregates or heterogeneous mixtures with organic matters, such as proteins, in biological and environmental systems. A large and growing body of research confirm that nanomaterial morphology as well as the degree of aggregation between nanomaterials influences nanomaterial interactions with their surroundings. Specifically, the structures/morphologies of nanoparticles determine their overall surface areas and corresponding surface reactivity (e.g. their catalytic activity). Nanoparticle transport properties (e.g. diffusion coefficient and extent of cellular uptake) are also determined by both their structures and surface properties. Unfortunately, techniques to characterize nanomaterial size and shape quantitatively, when nanomaterials have complex geometries or persist as aggregates, are lacking. Hydrodynamic sizes of nanoparticles and their aggregates can be inferred by dynamic light scattering (DLS) or nanoparticle tracking analysis (NTA). However, since these techniques are relied on the scattering light intensity properties, sizes of polydisperse sub 30 nm particles cannot be effectively measured in those techniques. For structure inference of aggregated nanomaterials, microscopy images have been used for qualitative visual analysis, but the quantitative morphology analysis technique is yet to be developed. Five studies in this dissertation are hence aimed to develop new techniques to provide improved morphology characterization of aggregated nanomaterials in various biological and environmental colloidal systems. Aggregation mechanism and behavior of nanoparticles in surrounding were examined as a function of their quantified aggregate morphologies. The first three studies (Chapters 2, 3, and 4) introduced a new gas-phase particle size measurement system, a liquid nebulization-ion mobility spectrometry (LN-IMS) technique, to characterize nanomaterials (down to 5 nm in characteristic size) and nanoparticle-protein conjugates. In other two studies (Chapters 5 and 6), three dimensional structures of homo-aggregates were quantified with the fractal aggregate model, and resulted fractal structures of aggregates were correlated to their transport properties in surroundings.
  • Thumbnail Image
    Item
    Developing Aggregate Loss Models For Obscure Insurance Exposures
    (2020-08) Albright, Robert
    In this paper we will examine how to apply parametric modeling with some simulation techniques to generate potential frequency and severity of claims distributions. The paper outlines the general theory of selecting appropriate statistical distributions for claims data and in maximizing model accuracy or fit. Two specific exposures, critical customer loss and supply chain disruption loss, are used as illustrations. From these distributions, an aggregate loss model is then proposed. The paper will discuss: 1. Possible ways to develop claims data from available market information for obscure insurance risks with application to specific examples. 2. Outline of the theory of parametric estimation. 3. Applying primarily parametric techniques to optimize the ‘fit’ of the estimated distributions for severity and frequency of claims distributions. 4. Development of possible aggregate loss models for the two specific exposures. 5. Proposed areas for further study.
  • Thumbnail Image
    Item
    Information Circular 20. Aggregate Resources Inventory, Twin Cities Metropolitan Area, Minnesota
    (Minnesota Geological Survey, 1984) Meyer, Gary N.; Jirsa, Mark A.
    Aggregate is derived from two major sources in the seven-county area. Surficial deposits of sand and gravel, or "natural" aggregate, are the primary source. These are deposits of rock detritus broken down and sorted by the actions of glacial ice and running water. A second and increasingly important source is carbonate (limestone and dolomite) bedrock, which is converted to aggregate by blasting and crushing. Because ongoing urban development both restricts access to sources of aggregate and requires more aggregate for construction, a report was published by the Metropolitan Council of the Twin Cities area as an aid for industrial and governmental planners dealing with the problems of aggregate supply and demand. The plates and Appendix A of that report summarized the data in this information circular.
  • Thumbnail Image
    Item
    Information Circular 46. Aggregate Resources Inventory of the Seven-County Metropolitan Area, Minnesota
    (Minnesota Geological Survey, 2000) Southwick, D.L.; Jouseau, M.; Meyer, G.N.; Mossler, J.H.; Wahl, T.E.
    Construction aggregates are sand, gravel, and crushed rock-bulk granular materials that are used in building and landscaping projects of all sizes and kinds. Most of the highest quality aggregate is used in the manufacture of concrete and top-grade asphalt paving. Aggregates of lower quality are used as fill, base-course for roads, and for a myriad of other purposes. Aggregate quality is determined by the mechanical and chemical properties of the constituent rock particles. In very general terms, the best aggregates for high-end uses contain particles that are strong (resist abrasion and fracturing), chemically inert (do not decompose, swell, or shrink on exposure to air, moisture, or road chemicals; do not react adversely with cement materials), and are of optimum size and shape for the specific engineering requirements. High-strength concrete for heavy-duty use such as highways and airport runways requires aggregate composed of particles that are strong and inert, and also have broken faces; i.e. they are not round and smooth. This broken shape enables the particles to lock up mechanically with one another rather than roll under stress, and improves the durability of the paving. Construction aggregate producers and their largest customers in the construction sector have recognized for many years that the aggregate resources available for mining within the seven- county metropolitan area are rapidly diminishing. The ultimate reason for this is urbanization, which on the one hand increases the demand for construction aggregates, and on the other, tends to remove aggregate-bearing lands from production through land development and zoning decisions that preclude mining. When sources of aggregate are eliminated locally, and become more remote from places of need, the costs of construction rise significantly. This is mainly because of the increased cost associated with aggregate transportation. Cost increases are felt most acutely in large projects such as freeway or airport runway construction that require huge volumes of high-quality aggregate for concrete. Local decision-makers have become increasingly aware of aggregate-resource issues over the past few decades. Most counties and townships are substantial purchasers of aggregate materials for road building and other purposes, and are therefore sensitive to aggregate costs. Many are also involved in the controversies between neighbors and aggregate producers over the noise, dust, truck traffic, and other environmental impacts (real or perceived) associated with aggregate- mining operations. In Minnesota, including the seven-county metropolitan area, the powers to regulate aggregate mining and associated industrial operations reside largely at the county, city, and township level. Issues of land-use planning and regulation that apply to the construction aggregates industry need to be resolved. Government entities, the aggregate industry, and citizens of the seven-county metropolitan area all require dependable information on the physical distribution of aggregate resources and the probable economic lifespan of the local resource base. This report and the companion geological maps on which it is based (Meyer and MossIer, 1999) were prepared to meet that need.