Wind loads on flat plate photovoltaic array fields (nonsteady winds)

Techniques to predict the dynamic response and the structural dynamic loads of flat plate photovoltaic arrays due to wind turbulence were analyzed. Guidelines for use in predicting the turbulent portion of the wind loading on future similar arrays are presented. The dynamic response and the loads dynamic magnification factor of the two array configurations are similar. The magnification factors at a mid chord and outer chord location on the array illustrated and at four points on the chord are shown. The wind tunnel test experimental rms pressure coefficient on which magnification factors are based is shown. It is found that the largest response and dynamic magnification factor occur at a mid chord location on an array and near the trailing edge. A technique employing these magnification factors and the wind tunnel test rms fluctuating pressure coefficients to calculate design pressure loads due to wind turbulence is presented

Escalator design features evaluation

Escalators are available with design features such as dual speed (90 and 120 fpm), mat operation and flat steps. These design features were evaluated based on the impact of each on capital and operating costs, traffic flow, and safety. A human factors engineering model was developed to analyze the need for flat steps at various speeds. Mat operation of escalators was found to be cost effective in terms of energy savings. Dual speed operation of escalators with the higher speed used during peak hours allows for efficient operation. A minimum number of flat steps required as a function of escalator speed was developed to ensure safety for the elderly

Evaluation of a metal shear web selectively reinforced with filamentary composites for space shuttle application. Phase 1 summary report: Shear web design development

An advanced composite shear web design concept was developed for the Space Shuttle orbiter main engine thrust beam structure. Various web concepts were synthesized by a computer-aided adaptive random search procedure. A practical concept is identified having a titanium-clad + or - 45 deg boron/epoxy web plate with vertical boron/epoxy reinforced aluminum stiffeners. The boron-epoxy laminate contributes to the strength and stiffness efficiency of the basic web section. The titanium-cladding functions to protect the polymeric laminate parts from damaging environments and is chem-milled to provide reinforcement in selected areas. Detailed design drawings are presented for both boron/epoxy reinforced and all-metal shear webs. The weight saving offered is 24% relative to all-metal construction at an attractive cost per pound of weight saved, based on the detailed designs. Small scale element tests substantiate the boron/epoxy reinforced design details in critical areas. The results show that the titanium-cladding reliably reinforces the web laminate in critical edge load transfer and stiffener fastener hole areas

Rocket measurements of electron temperature in the E region

The rocket borne equipment, experimental method, and data reduction techniques used in the measurement of electron temperature in the E region are fully described. Electron temperature profiles from one daytime equatorial flight and two nighttime midlatitude flights are discussed. The last of these three flights, Nike Apache 14.533, showed elevated E region temperatures which are interpreted as the heating effect of a stable auroral red arc

Investigations of the lower and middle atmosphere at the Arecibo Observatory and a description of the new VHF radar project

The atmospheric science research at the Arecibo Observatory is performed by means of (active) radar methods and (passive) optical methods. The active methods utilize the 430 NHz radar, the S-band radar on 2380 MHz, and a recently constructed Very High Frequency (VHF) radar. The passive methods include measurements of the mesopause temperature by observing the rotational emissions from OH-bands. The VHF radar design is discussed

Method to determine the optimal parameters of the Arecibo 46.8-MHz antenna system

The spherical reflector at the Arecibo Observatory (AO) offers great advantages for the design of simple and inexpensive high performance steerable antennas at VHF. Light and small feeds have the added benefit that they can be quickly installed in the Arecibo platform. It is important to evaluate the performance of any given feed including the effects of the spherical reflector. The optimization is emphasized of two parameters, namely, the distance below the focal point of the reflector and the beam width of a point feed. For the design of the feed at 46.8 MHz at the AO there were other requirements independent of MST (mesosphere stratosphere troposphere) work. The design of the primary array is discussed along with its performance with the AO spherical reflector

Identifying opportunities for co-production of commodities and water quality improvements in agricultural landscapes in the US Cornbelt

One of the most striking features of the US Cornbelt is the degree to which it has been designed, constructed, and intricately managed by humans for the production of agricultural products – primarily row-crop corn and soybeans. The production of provisioning ecosystem services, such as row-crop corn and soybeans, often comes at a tradeoff to other ecosystem services, such as enhanced water quality for aquatic life, recreation, and human consumption. Best management practices (BMPs) are tools that landowners can implement and manage as a way to co-produce row-crop corn and soybeans and enhanced water quality in extensively managed agricultural landscapes. Yet, selecting how and where to locate BMPs to impact aggregate ecosystem service outcomes, such as enhanced water quality, is a complex decision-making process that often involves multiple stakeholders and objectives. This research evaluates opportunities to improve the efficiency of BMP placement and management within and among crop fields and within watersheds to co-produce provisioning and regulating ecosystem services (ES), specifically row-crop corn and soybeans and enhanced water quality, in the US Cornbelt. This dissertation includes three distinct studies across three, nested scales (sub-field, field, and watershed) to examine environmental, economic, and social opportunities and tradeoffs associated with the implementation and management of BMPs designed to reduce nitrate loss to surface waters in central Iowa. To assess nitrate-nitrogen (hereafter nitrate) retention in vegetative BMPs, the relationship between nitrate retention and plant species composition was examined in nine different monocultural and polycultural communities in a plot-based experiment. Results show a small, but significant difference between monocultural and polycultural plant communities in their ability to retain nitrate. On average, polycultural communities retained 31.5% (95% CI – 1.0%, 53.2%) more nitrate than monocultural communities. This difference was driven largely by alfalfa, which was planted as a monoculture in this experiment; alfalfa retained 63.0% (95% CI – 32.9%, 80.0%) less nitrate than the polycultural communities. Among polycultural communities, which varied in species richness (2-14 species per community), no impact was found of plant diversity on nitrate retention. To understand farmers’ and farmland owners’ willingness to participate in new spatially targeted conservation planning frameworks designed to increase BMP efficacy, 18 farmers and farmland owners whose fields were identified via a spatial targeting technique focusing on soil and nutrient loss were interviewed in two watersheds in central Iowa. Results suggest that farmers and farmland owners often recognized the importance of producing a diverse suite of on- and off-farm ecosystem services, but lacked the context, information, certainty, and incentives to manage for them. Farmers and farmland owners were receptive to using technologies to target BMPs to areas with known resource concerns, but expressed concerns about applications in their fields, and perceived challenges related to cost, management complexity, coordination with government programs, and loss of autonomy. For broad acceptance, a spatially targeted conservation approach would need to be paired with expanded partnerships, trusted technical service, and adaptation incentives to reduce farm-level economic tradeoffs. To evaluate the cost and effect on water quality from nitrate loss under spatially targeted alternative land management scenarios, an innovative spatially targeted conservation protocol, coupled with a GIS-based landscape planning tool, was developed, applied, and evaluated in an Iowa watershed. We found large reductions in watershed-level nitrate loss could be achieved through coordinated placement of BMPs on high-contributing parcels with limited reduction of cultivated land, resulting in improved surface water quality at relatively low economic costs. For example, one landscape scenario with wetlands, cover crops, and saturated buffers removed less than 5% of cultivated area and reduced nitrate loss by an estimated 49%, exceeding the Iowa Nutrient Reduction Strategy goal for enhancing water quality. Annualized establishment and management costs of landscape scenarios that met the nonpoint source nitrogen reduction goal in the watershed varied from $3.16 to$3.19 million (2017 USD). These results highlight the potential to minimize land-use tradeoffs by coupling targeted conservation and planning tools to help stakeholders achieve aggregate surface water quality outcomes within agricultural landscapes. Taken cumulatively, this research suggests opportunities for improving the design, implementation, and management of BMPs to produce row-crop corn and soybeans while enhancing water quality in agricultural landscapes. Innovative and purposeful BMP design, stakeholder collaboration, and decision tools, programming, and incentives will be important components of conservation planning and water quality achievements

The impact of the Patient Protection and Affordable Care Act’s risk adjustment program on adverse selection : first year case study.

In 2014 the Patient Protection and Affordable Care Act (ACA) implemented a risk adjustment program to stabilize premiums and neutralize premiums in the individual health insurance marketplace. This dissertation will examine the impact of the ACA risk adjustment program on adverse selection for one insurer during 2014. This study utilized enrollment and claims data for one insurer and employs graphical analysis to test for adverse selection. Previous studies have been unable to utilize actual insurer data to test for adverse selection in under the ACA risk adjustment program. Until the implementation of the ACA, insurers relied on underwriting methods to avoid being adversely selected. The ACA has removed the underwriting model by requiring insurers to move to a community rated model for pricing plans. This approach, along with risk adjustment was intended, by the Department of Health and Human Services (HHS), to attract insurers to participate in the individual health insurance marketplaces. Unfortunately, not all states enjoyed a large contingent of participating insurers which consequently had a dramatic financial impact on certain insurers being adversely selected. This dissertation discusses the potential drivers of adverse selection. In addition, the study examines potential improvements to help balance the risk pool and move toward the intended goal of risk adjustment