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Browsing by Subject "distribution"

Now showing 1 - 9 of 9
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    Can Local Food Go Mainstream?
    (Choices Magazine, Agricultural & Applied Economics Association, 2010) King, Robert P.; Gomez, Miguel I.; DiGiacomo, Gigi
    The supermarket is one of the 20th Century’s most important marketing innovations. The concept of the supermarket emerged in the 1930s, and supermarkets came to dominate food retailing in the two decades immediately after World War II. Made possible by rapid suburbanization of American cities and expansion of ownership of automobiles and refrigerators, supermarkets transformed business processes and competition for customers at the retail level. They also fostered expansion and new efficiencies for wholesalers and created new opportunities for food manufacturers to develop products for mass audiences. The basic hub and spoke distribution system that has evolved for supermarkets is built around large distribution centers located near interstate highways. These distribution centers receive full semi-trailer loads of product from suppliers and then send full semi-trailers out to individual stores daily or several times per week. Loads sent to stores are comprised of relatively small quantities of thousands of individual SKUs, or stock keeping units, needed to replenish the inventory of tens of thousands of SKUs stored on self-service shelves in a typical store. This system, which is supplemented by deliveries from specialty distributors and direct store deliveries by some suppliers, economizes on transportation and labor. With electronic transmission of orders and payment and computer-based tools that assist with ordering, pricing, and inventory management, this distribution system also keeps transaction costs to a minimum. It is ideally suited for sourcing consistent quality products at low cost from wherever they are available and so has been an integral part of an increasingly national and global food system. This mainstream supermarket distribution system favors large scale suppliers and facilitates long distance movement of products. Supermarket wholesale and retail companies usually prefer to work with a small number of large, reliable suppliers. At the same time, this system is remarkably resilient and quick to adapt. Can it be an effective channel for meeting the rapidly growing demand for local food products? Are there meaningful, long run prospects for a significant “relocalization” of supermarket offerings? While definitive answers to these questions are not yet apparent, there is emerging evidence that helps clarify how the relationship between the local foods movement and the supermarket industry may evolve.
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    Configuration and Performance of Hydraulic Transformer Power Distribution Systems
    (2016-09) Gagnon, Pieter
    Hydraulic transformers implemented in a common pressure rail architecture have been suggested as a means to efficiently distribute hydraulic power to a system of actuators. This thesis explores the role that the configuration of the system plays in the operating region and efficiency performance of the power distribution system. The primary tool used in this thesis is a dynamic loss model of a hydraulic transformer. Full mathematical documentation and experimental parameter tuning are described. Six configurations for distributing power with a hydraulic transformer are presented, and it is shown that each configuration has a unique operating region and efficiency trend. The hydraulic circuit is given for a port switching transformer that utilizes valves to switch between configurations during operation, and experimental tests demonstrate successful switching on a prototype machine. The maximum displacements of the two rotating groups within a set of hydraulic transformers distributing power to linear actuators driving the hip, knee, and ankle joints of a humanoid robot are optimized to maximize efficiency over a walking gait duty cycle. The resulting size ratios of the groups vary from a 1:1 ratio to a 1:2.4 ratio for the three duty cycles investigated. A comparison of the hydraulic transformer architecture against a throttling valve architecture for the humanoid robot indicates that the transformer system can achieve a distribution efficiency of 47.6%, which is a 31.9% increase over the throttling architecture distribution efficiency of 16.0%. The transformer system consumes 142 J to drive a single step of the walking gait, which is a decrease of 281 J from the 422 J required by the throttling architecture. This thesis thoroughly captures the efficiency performance and operating region of hydraulic transformers, and demonstrates how system configurations can improve the performance of the system beyond what has been generally considered in previous literature. These factors can then be weighed along with complexity, size, control performance, production cost, and other such metrics to enable a decision as to whether transformers are an appropriate power distribution architecture for a given application.
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    Karner Blue Butterfly: A Symbol of a Vanishing Landscape
    (Minnesota Agricultural Experiment Station, 1994) Andow, David A.; Baker, Richard J.; Lane, Cynthia P; Andow, D.A.; Baker, R.J.; Lane, C.P.
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    North Circle Project
    (2008) Dietel, Randall
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    Order Trichoptera Kirby, 1813 (Insecta), Caddisflies
    (Magnolia Press, 2007) Holzenthal, Ralph W.; Blahnik, Roger J.; Prather, Aysha L.; Kjer, Karl M.
    The taxonomy, diversity, and distribution of the aquatic insect order Trichoptera, caddisflies, are reviewed. The order is among the most important and diverse of all aquatic taxa. Larvae are vital participants in aquatic food webs and their presence and relative abundance are used in the biological assessment and monitoring of water quality. The species described by Linnaeus are listed. The morphology of all life history stages (adults, larvae, and pupae) is diagnosed and major features of the anatomy are illustrated. Major components of life history and biology are summarized. A discussion of phylogenetic studies within the order is presented, including higher classification of the suborders and superfamilies, based on recent literature. Synopses of each of 45 families are presented, including the taxonomic history of the family, a list of all known genera in each family, their general distribution and relative species diversity, and a short overview of family-level biological features. The order contains 600 genera, and approximately 13,000 species.
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    Plant phenology, growth, freezing damage, and carbon gain data observed from 2017 to 2018 on wood plants growing at Bagley Nature Area in Duluth, MN
    (2020-05-26) O'Connell, Erin M; Savage, Jessica A; oconn877@d.umn.edu; O'Connell, Erin M; Savage research team
    These data were collected for a project comparing the leaf phenology, carbon gain, growth, and freezing susceptibility of four invasive and four native species. Leaf phenology and stem growth were observed for ten individuals per understory wood shrubs species. Freezing damage was experimentally assessed for each species and minimum temperatures in the species' native and exotic ranges were determined. Carbon gain was modeled for six individuals per species based on photosynthetic light response curves, leaf phenology, and understory light.
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    Revision of the Nearctic species of the caddisfly genus Wormaldia McLachlan (Trichoptera: Philopotamidae)
    (Magnolia Press, 2008) Munoz-Quedada, Fernando J.; Holzenthal, Ralph W.
    The genus Wormaldia McLachlan 1865 (Trichoptera: Philopotamidae: Philopotaminae) is one of eight Philopotamidae genera found in the New World. In the Nearctic Region five genera are reported: Chimarra, Dolophilodes, Fumonta, Sisko, and Wormaldia. This last genus is diverse and widely distributed from Canada to South America; for the Nearctic Region the following species are reported: W. anilla (Ross, 1941), Canada, USA; W. arizonensis (Ling, 1938), Mexico, USA; W. gabriella (Banks, 1930), Canada, USA; W. gesugta Schmid, 1968, USA; W. hamata Denning, 1951, USA; W. lacerna Denning, 1958, USA; W. laona Denning, 1989, USA; W. moesta (Banks, 1914), Canada, USA; W. mohri (Ross, 1948), USA; W. occidea (Ross, 1938), Canada, USA; W. oconee Morse, 1989, USA; W. pachita Denning, 1956, USA; W. planae Ross and King, 1956, USA, W. shawnee (Ross, 1938), USA; W. strota (Ross, 1938), USA; and W. thyria Denning, 1950, USA. Diagnoses, redescriptions, and illustrations of the forewing, the hind wing, and the male genitalia of the 16 species are provided. New state distribution records are given for W. anilla, W. gabriella, W. occidea, W. planae, and W. shawnee. Two undescribed Nearctic species are diagnosed, described, and illustrated: Wormaldia birneyi, new species, from USA (California) and W. clauseni, new species, from Canada (British Columbia). A key for identification of males of these 18 species of Wormaldia is provided, as well as maps of their Nearctic distributions.
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    Shear Distribution in Prestressed Concrete Girder Bridges
    (2015-10) Dymond, Benjamin
    As shear requirements for prestressed concrete girders have changed, some structures designed using older specifications do not rate well with current methods. However, signs of shear distress have not been observed in these bridge girders and they are often deemed to be in good condition. The primary objective of this research program was to investigate the accuracy of existing shear distribution factors, which are used to estimate bridge system live load effects on individual girders, and provide recommendations on shear distribution to be used in Minnesota with three components: a full-scale laboratory bridge subjected to elastic and inelastic behavior, field testing of bridges, and a numerical parametric study. Results from the components were integrated to develop recommendations for rating prestressed concrete girder bridges. Laboratory bridge inelastic testing indicated shear force redistribution after cracking and before ultimate failure. Use of elastic distribution factors is conservative for shear distribution at ultimate capacity. Elastic laboratory testing was used to validate the finite element modeling technique and study the behavior of a traffic barrier and end diaphragm, which affected shear distribution. Ignoring the effects of the barrier was conservative and ignoring the effects of the end diaphragm was slightly inaccurate by 4 to 6 percent but was warranted for simplicity. Parametric study results indicated that a ratio of longitudinal stiffness to transverse stiffness could be used as a screening tool. If the stiffness ratio was less than 1.5, shear demand from a simple, conservative grillage analysis may be more accurate than shear demand from AASHTO distribution factor methods. Grillage analysis shear demand results due to permit trucks may also be more accurate, regardless of the screening tool ratio.
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    Wetland bird case study for application of habitat association models across Great Lakes and Prairie Pothole regions
    (2022-12-08) Elliott, Lisa H; Bracey, Annie M; Niemi, Gerald J; Johnson, Douglas H; Gehring, Thomas M; Gnass Giese, Erin E; Fiorino, Giuseppe E; Howe, Robert W; Lawrence, Gregory J; Norment, Christopher J; Tozer, Douglas C; Igl, Lawrence D; harnx012@umn.edu; Elliott, Lisa H; Coastal Wetland Monitoring Program; Great Lakes Marsh Monitoring Program; Dakotas Wetland Survey
    Species often exhibit regionally specific habitat associations, and, thus, habitat association models developed in one region might not be accurate or even appropriate for other regions. Three programs to survey wetland-breeding birds covering (respectively) North American wetland breeding bird survey programs in Great Lakes coastal wetlands, inland Great Lakes wetlands, and the Prairie Pothole Region offer an opportunity to test whether regionally specific models of habitat use by wetland-obligate breeding birds are transferrable across regions. This dataset includes wetland bird point count and habitat characteristics data from the Great Lakes Coastal Wetland Monitoring Program (2016-2017) and Great Lakes Marsh Monitoring Program (1995-1997 and 2016-2017). These data are then combined with publicly available data from the Dakotas Wetland Survey (1995-1997). The included code files cover the creation and selection of habitat association models, and test the transferability of these models across datasets. These data are now released to accompany publication of "Application of habitat association models across regions: useful explanatory power retained in wetland bird case study."