12 resultados para 342.06
em Iowa Publications Online (IPO) - State Library, State of Iowa (Iowa), United States
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Vision: Each Iowans will have equal access to information and ideas in order to participate knowledgeably and productively in a democratic society and to lead an enriched life through lifelong learning. Mission: Helping libraries provide the best possible service to Iowans.
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A quarterly report from the Iowa Department of Transportation regarding the Motor Vehicle Division building project status.
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This annual report covers highlights and financial information for fiscal year 2006 for the ICN. Any questions may be directed to Public Relations Manager Gail Geery.
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Report of expenditures from the biodiesel fuel revolving fund for biodiesel fuel used in Iowa Department of Transportation vehicles.
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Division of Deaf Services Biennal Report for Fiscal Years 2005 and 2006, part of Department of Human Rights.
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Five test flights were conducted to study the use of Global Positioning System (GPS) in Photogrammetry, three in Iowa, one each in California and Texas. These tests show that GPS can be used to establish ground control by the static method and to determine camera location by the kinematic method. In block triangulation, six GPS controls are required and additional elevation control along the centerline is also required in strip triangulation. The camera location determined by aerial triangulation depends on the scale of the photography. The 1:3000 scale photography showed that the absolute accuracy of the camera location by GPS is better than five centimeters. The 1:40000 scale photography showed that the relative accuracy of the camera location by GPS is about one millimeter. In a strip triangulation elevation control is required in addition to the camera location by GPS. However, for block triangulation camera location by GPS is sufficient. Pre-targeting of pass and tie points gives the best results in both block and strip triangulation. In normal mapping for earth work computations the use of 1:6000 scale photography with GPS control instead of 1:3000 scale is recommended. It is recommended that research be done in the use of GPS for navigation in aerial photographic missions. It is highly recommended that research be done in the use of GPS to determine tip and tilt of the aerial camera, that is required in stereoplotting.
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The current study investigated the effect of fly ash class, source and amount on the compressive strength and freeze-thaw durability of fly ash concrete. Concrete aggregates of varying quality were also included as test variables. The current results and those obtained from previous laboratory and field work indicate that compressive strength can·be affected by fly ash class, source and amount while aggregate quality is shown to have no effect on strength. Freeze-thaw durability of fly ash concrete is strongly affected by aggregate quality and to a lesser degree by fly ash class, amount and source.
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In work-zone configurations where lane drops are present, merging of traffic at the taper presents an operational concern. In addition, as flow through the work zone is reduced, the relative traffic safety of the work zone is also reduced. Improving work-zone flow-through merge points depends on the behavior of individual drivers. By better understanding driver behavior, traffic control plans, work zone policies, and countermeasures can be better targeted to reinforce desirable lane closure merging behavior, leading to both improved safety and work-zone capacity. The researchers collected data for two work-zone scenarios that included lane drops with one scenario on the Interstate and the other on an urban arterial roadway. The researchers then modeled and calibrated these scenarios in VISSIM using real-world speeds, travel times, queue lengths, and merging behaviors (percentage of vehicles merging upstream and near the merge point). Once built and calibrated, the researchers modeled strategies for various countermeasures in the two work zones. The models were then used to test and evaluate how various merging strategies affect safety and operations at the merge areas in these two work zones.
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Early deterioration has shown up in a number of Iowa PCC pavements placed between 1986 and 1994. Research has shown that inadequate air content and spacing factors have contributed to the deterioration. Ettringite infilling of air voids is nearly always noted in cores obtained from pavements exhibiting deterioration. This research is to document the early deterioration on I-29 in Pottawattamie county from MP 59 to 72 in both directions.
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This study investigates the properties imparted to extruded asphalt curb mixes by five different additives. The AC used in these mixes was also tested with various amounts of the additives. All of the additives stiffened the AC as indicated by a reduction of penetration and increased viscosity. Only the powdered asphalts, gilsonite and Witcurb improved the Marshall stability and the indirect tensil strength enough to justify their use in curb mixes.
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In 1990, early distress had shown up on US 20 in Hamilton/Webster counties, three years after paving. Since that time, over a dozen more projects, constructed between 1984 and 1994, have been found to exhibit similar early distress. Several changes to the concrete and Portland cement specifications occurred in 1994 and 1996. This study was undertaken to investigate in place concrete pavements before and after specification changes were implemented. The objective of this research is to evaluate the impact of Portland cement and concrete specification changes made in 1994 and 1996 on PCC durability. Cores were obtained in 1998 and 2003 from projects constructed in 1992, before specification changes, and 1997 after specification changes. The following is a brief summary of the conclusions: 1. The pavements in the study constructed under the new specifications are performing much better after 5 years of service than the pavements constructed under the old specifications. 2. According to ISU, micro-cracking is evident in all concrete that has been in service, due to thermal stresses and loading stresses. Also, the low vacuum SEM will desiccate the concrete enough to cause micro-cracking. The SEM should not be used as a tool to indicate micro-cracking. 3. Use of Type II cement (C3A <8%) and a 3.0% SO3 limit does not completely eliminate ettringite infilling in air voids, as indicated in the bottom of the 1997 cores. 4. In areas of high moisture (bottom of the core), infilling is present in most of the 1997 cores. 5. Low air content and high spacing factor in the top of 1992 cores apparently causes F/T cycling cracking and then increased moisture paths from cracking causes infilling. 6. Use of ground granulated blast furnace slag (GGBFS) and fly ash reduces ettringite infilling either by diluting the aluminate (C3A) or lowering permeability, which slows ingress of moisture. 7. The specification changes that made the biggest impact on pavement durability are the limits on vibration and increase in air content in September 1994. 8. Investigations of cores from pavements placed in 2002 and 2003 indicate improved air contents and spacing factors. In-place air content and spacing factors should be monitored to determine if appropriate air void parameters are being met.
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Crop and livestock summaries for the state of Iowa, produced by the Iowa Department of Agriculture. Previously Agri-News