3,003 research outputs found
Dynamics of Fish Assemblages Associated with an offshore Artificial Reef in the Southern Mid-Atlantic Bight
Spatial Patterns of Estuarine Habitat Type Use and Temporal Patterns in Abundance of Juvenile Permit, Trachinotus falcatus, in Charlotte Harbor, Florida
The life history of many marine fishes is a 2-phase cycle: juveniles and adults make up a demersal phase, whereas larvae are planktonic. Determining ontogenetic patterns of habitat type use of the demersal phase has important management and habitat conservation implications for species that use coastal habitat types as juveniles. Juvenile permit, Trachinotus falcatus, are presumed to be limited to beaches exposed to open ocean, but few studies have addressed juvenile permit use of estuarine habitat types. Ten years of fisheries-independent monitoring data from a subtropical estuary were analyzed to determine habitat type use patterns and seasonality of juvenile permit. Shallow (\u3c 2 m) habitat types in Charlotte Harbor, Florida, were sampled with 21 m and 183 m seines from 1991 through 2000. Juvenile permit were most abundant along sandy beaches in the lower estuary and were in densities similar to or higher than along exposed coastal beaches reported in other studies. Size of captured permit ranged from 15 to 360 mm standard length. Small juveniles (\u3c 100 mm) were present almost exclusively from June to December. Both small and large (∅ 100 mm) juveniles were most abundant over shallow bottom adjacent to unvegetated beach shorelines. These findings indicate that post-settlement permit recruit seasonally to specific estuarine habitat types. Then, as they grow, they shift to other habitat types, before migrating out of the estuary. Since identification of the suite of juvenile habitat types is prerequisite to determining their nursery value, and many estuarine habitat types are under anthropogenic stress, research on the relative importance of estuarine nurseries for juvenile permit is warranted
Relationships between observed pore and pore-throat geometries, measured porosity and permeability, and indirect measures of pore volume by nuclear magnetic resonance
Carbonate reservoirs are a network of pores and connecting pore-throats that
contain at least half of the world's oil. Genetic classification of carbonate pores enables
one to map the pore types that have greatest influence on reservoir performance.
Though NMR logging has been used to estimate pore sizes, it has not been used to
identify genetic pore types or to aid in determinations of reservoir quality for different
pore assemblages.
Five genetic pore types identified in 40 carbonate and 7 sandstone samples were
subjected to NMR measurements. Results reveal close correspondence between NMRderived
pore volumes and 2-D pore size and shape gleaned from petrographic image
analysis. Comparisons of real and synthetic pore shapes showed that shapes of all pore
types in the medium size range of 0.02-0.5mm can be reliably compared with synthetic
varieties, but such comparisons were unreliable for vuggy pores smaller than 0.5mm. T2
relaxation times for depositional pores exhibit low amplitude, narrow wavelength
responses. Moldic pores produced medium amplitude, asymmetrical wavelength responses, and intercrystalline pores show high amplitude, narrow wavelength
responses. NMR-derived pore volumes on pores with ferroan dolomite interiors
underestimated pore diameter by up to 3 orders of magnitude. Calculated pore-throat
sizes from MICP data correlate strongly with measured permeability.
Samples with high, intermediate, or low poroperm values displayed characteristic
T2 curves confirming that reservoir quality can be estimated from NMR measurements.
Future work is expected to show that NMR logging can estimate reservoir quality at
field scale and aid in mapping flow units in compartmentalized reservoirs
A System for Wintering Beef Heifers Using Dried Distillers Grains
A two-year experiment compared two systems for wintering pregnant heifers. The standard system used by the ranch served as the control (CON) and the treatment system (TRT) included a dried distillers grains based supplement. Heifers in the TRT system were heavier and had greater body condition score at end of supplementation. Calving difficulty, percentage of live calves weaned and subsequent pregnancy rate were similar between systems. Calves born to heifers in the TRT system were heavier at birth and weaning. The TRT system cost $10.47/heifer less than the CON system and resulted in equivalent or improved heifer and calf growth performance
Microgrids for Improving Manufacturing Energy Efficiency
Thirty-one percent of annual energy consumption in the United States occurs within the industrial sector, where manufacturing processes account for the largest amount of energy consumption and carbon emissions. For this reason, energy efficiency in manufacturing facilities is increasingly important for reducing operating costs and improving profits. Using microgrids to generate local sustainable power should reduce energy consumption from the main utility grid along with energy costs and carbon emissions. Also, microgrids have the potential to serve as reliable energy generators in international locations where the utility grid is often unstable. For this research, a smart microgrid system was designed as part of an innovative load management option to improve energy utilization through active Demand-Side Management (DSM). An intelligent active DSM algorithm was developed to manage the intermittent nature of the microgrid and instantaneous demand of the site loads. The controlling algorithm required two input signals; one from the microgrid indicating the availability of renewable energy and another from the manufacturing process indicating energy use as a percent of peak production. Based on these inputs the algorithm had three modes of operation: normal (business as usual), curtailment (shutting off non-critical loads), and energy storage. The results show that active management of a manufacturing microgrid has the potential for saving energy and money by intelligent scheduling of process loads
A Novel Microgrid Demand-Side Management System for Manufacturing Facilities
Thirty-one percent of annual energy consumption in the United States occurs within the industrial sector, where manufacturing processes account for the largest amount of energy consumption and carbon emissions. For this reason, energy efficiency in manufacturing facilities is increasingly important for reducing operating costs and improving profits. Using microgrids to generate local sustainable power should reduce energy consumption from the main utility grid along with energy costs and carbon emissions. Also, microgrids have the potential to serve as reliable energy generators in international locations where the utility grid is often unstable.
For this research, a manufacturing process that had approximately 20 kW of peak demand was matched with a solar photovoltaic array that had a peak output of approximately 3 KW. An innovative Demand-Side Management (DSM) strategy was developed to manage the process loads as part of this smart microgrid system. The DSM algorithm managed the intermittent nature of the microgrid and the instantaneous demand of the manufacturing process. The control algorithm required three input signals; one from the microgrid indicating the availability of renewable energy, another from the manufacturing process indicating energy use as a percent of peak production, and historical data for renewable sources and facility demand. Based on these inputs the algorithm had three modes of operation: normal (business as usual), curtailment (shutting off non-critical loads), and energy storage.
The results show that a real-time management of a manufacturing process with a microgrid will reduce electrical consumption and peak demand. The renewable energy system for this research was rated to provide up to 13% of the total manufacturing capacity. With actively managing the process loads with the DSM program alone, electrical consumption from the utility grid was reduced by 17% on average. An additional 24% reduction was accomplished when the microgrid and DSM program was enabled together, resulting in a total reduction of 37%. On average, peak demand was reduced by 6%, but due to the intermittency of the renewable source and the billing structure for peak demand, only a 1% reduction was obtained. During a billing period, it only takes one day when solar irradiance is poor to affect the demand reduction capabilities. To achieve further demand reduction, energy storage should be introduced and integrated
Effects of a Severe Cold Event on the Subtropical, Estuarine-Dependent Common Snook, Centropomus undecimalis
The effects of infrequent disturbance events on marine fishes are often difficult to determine, due largely to lack of sufficient pre- and post-disturbance event data. In January 2010, subtropical southwestern Florida (USA) experienced extreme cold for 13 days, which caused extensive mortality of many fish species. The effect of this severe cold event on common snook (Centropomus undecimalis), an economically important gamefish, was assessed using three years (2007-2009) of pre-event and one year (2010) of post-event data from a tag-recapture program conducted over 28 km of Gulf of Mexico barrier islands of Florida. All metrics pointed to a significant effect of the severe cold event: post-disturbance apparent survival of marked fish was 96-97% lower than pre-disturbance, and post-disturbance common snook abundance was 75.57% and 41.88% less than in 2008 and 2009, the two years immediately pre-event. Although severe cold events have impacted subtropical Florida in the past, these events are infrequent (the previous recorded event was \u3e30 years prior), and documentation of the impacts on common snook have not previously been published
Urea Inclusion in Forage Based Diets Containing Dried Distillers Grains
Two experiments evaluated supplemental degradable intake protein requirements when dried distillers grains were fed as an energy source in forage-based diets. Diets were formulated to be greater than 100 g/day deficient in degradable intake protein but with excess metabolizable protein. In both experiments, no response in performance was observed when urea was added to the diet. Sufficient urea was probably recycled to correct the degradable intake protein deficiency. These studies indicate adding urea to meet the degradable intake protein requirement is not necessary when dried distillers grains are fed as an energy source in forage-based diets
Tactile Data Entry for Extravehicular Activity
In the task-saturated environment of extravehicular activity (EVA), an astronaut's ability to leverage suit-integrated information systems is limited by a lack of options for data entry. In particular, bulky gloves inhibit the ability to interact with standard computing interfaces such as a mouse or keyboard. This paper presents the results of a preliminary investigation into a system that permits the space suit gloves themselves to be used as data entry devices. Hand motion tracking is combined with simple finger gesture recognition to enable use of a virtual keyboard, while tactile feedback provides touch-based context to the graphical user interface (GUI) and positive confirmation of keystroke events. In human subject trials, conducted with twenty participants using a prototype system, participants entered text significantly faster with tactile feedback than without (p = 0.02). The results support incorporation of vibrotactile information in a future system that will enable full touch typing and general mouse interactions using instrumented EVA gloves
Effects of Supplementing Lactating, June-calving Cows on Second-calf Pregnancy Rates
A two year experiment evaluated the influence of supplementation pre-breeding on second-calf pregnancy rates in June-calving heifers. For 60 days before start of the breeding season, heifers were assigned to one of two treatments: supplementation of dried distillers grains (1.5 lb/day) to meet energy and metabolizable protein requirements or unsupplemented control. Supplementation improved body condition score during the supplementation period and resulted in increased body condition score at weaning. In year 1, feeding supplement to the dam did not change calf weight gain but feeding supplement increased calf weight in year 2. Pregnancy rates were 90% and not changed by supplementation
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