Tracking filter and multi-sensor data fusion

In this paper factorization filtering, fusion filtering strategy and related algorithms are presented. Some results of implementation and validation using realistic data are given

Biology of the Striped Bass, Morone saxatilis, in Beaver Reservoir, Arkansas

Growth, length-weight relationship, maturation and food habits of striped bass from Beaver Reservoir were studied. No significant difference in growth in length between sexes was found. Growth of the Beaver Reservoir striped bass was similar to that of anadromous and freshwater populations. Males and females showed significant difference in length-weight relationship, and females exhibited isometric growth. The gonosomatic indices (GSI) of males ranged from 4.50 to 7.09 and were classified as mature fish. Female striped bass with GSI of 2.62 and above had three size groups of ova and were considered as maturing and mature. The food was primarily composed of gizzard shad. Both the possible impact of striped bass on the ecosystem of Beaver Reservoir and future research are discussed

Limits on the HI content of the dwarf galaxy Hydra II

Sensitive 21cm HI observations have been made with the Green Bank Telescope toward the newly-discovered Local Group dwarf galaxy Hydra II, which may lie within the leading arm of the Magellanic Stream. No neutral hydrogen was detected. Our 5-sigma limit of MHI < 210 solar masses for a 15 km/s linewidth gives a gas-to-luminosity ratio MHI/L_V < 2.6 x 10^{-2} Mo / Lo. The limits on HI mass and MHI/L_V are typical of dwarf galaxies found within a few hundred kpc of the Milky Way. Whatever the origin of Hydra II, its neutral gas properties are not unusual.Comment: Accepted for publication in Astronomy & Astrophysic

Surface chlorophyll anomalies induced by mesoscale eddy-wind interactions in the northern Norwegian Sea

The substantial productivity of the northern Norwegian Sea is closely related to its strong mesoscale eddy activity, but how eddies affect phytoplankton biomass levels in the upper ocean through horizontal and vertical transport-mixing has not been well quantified. To assess mesoscale eddy induced ocean surface chlorophyll-a concentration (CHL) anomalies and modulation of eddy-wind interactions in the region, we constructed composite averaged CHL and wind anomalies from 3,841 snapshots of anticyclonic eddies (ACEs) and 2,727 snapshots of cyclonic eddies (CEs) over the period 2000-2020 using satellite altimetry, scatterometry, and ocean color products. Results indicate that eddy pumping induces negative (positive) CHL anomalies within ACEs (CEs), while Ekman pumping caused by wind-eddy interactions induces positive (negative) CHL anomalies within ACEs (CEs). Eddy-induced Ekman upwelling plays a key role in the unusual positive CHL anomalies within the ACEs and results in the vertical transport of nutrients that stimulates phytoplankton growth and elevated productivity of the region. Seasonal shoaling of the mixed layer depth (MLD) results in greater irradiance levels available for phytoplankton growth, thereby promoting spring blooms, which in combination with strong eddy activity leads to large CHL anomalies in May and June. The combined processes of wind-eddy interactions and seasonal shallowing of MLD play a key role in generating surface CHL anomalies and is a major factor in the regulation of phytoplankton biomass in the northern Norwegian Sea

Estimated Growth and Standing Crop of Largemouth Bass (Micropterus salmoides) from Lake Elmdale

Electro-fishing gear was used to make shoreline population estimates of largemouth bass (Micropterus salmoldes) in Lake Elmdale, Washington County, Arkansas, during September 1979. The population density was estimated to be 1541 bass/Km² with a standing crop of 30.4 kg/ha. The length-weight relationship was calculated as W = 0.00001 504L^2.97, and the total length-scale radius relationship as L = 41.75 + 1.23 St. The average condition coefficient(K) was 1.31. In comparison with four other Arkansas lakes the population density of largemouth bass was highest in Lake Elmdale while the growth rate was lowest

ESTIMATION OF STRATUM VARIANCES IN PLANNING OF CROP ACREAGE SURVEYS

Abstract: A modelling approach is used to obtain initial estimates of stratum crop acreage variances for designing crop surveys, particularly those using the remote sensing technology. The present methodology is developed based on the concept of stratum variance as a function of the sampling unit size and it uses primarily the historical crop statistics which are commonly available in most countries. Methods are proposed for the determination of stratum variances corresponding to unit sizes different from the sampling unit size and for which the historical crop statistics can be used. The methodology is applied to estimate stratum variances for wheat in the U.S. Great Plains. An evaluation of these estimates made by comparing them to those obtained from certain satellite sample data shows that the proposed method leads to reliable stratum variance estimates for a fairly large size (5 x 6 nautical miles area segment) sampling unit

Ultrasonic Pretreatment of Corn Slurry in Batch and Continuous Systems

The effects of ultrasonication of corn slurry, on particle size distribution and enzymatic hydrolysis was studied for the dry-grind mill ethanol industry. Two independent ultrasonic experiments were conducted at a frequency of 20 kHz; in batch and continuous systems. The ground corn slurry (33% m/v) was pumped at flow rates 10-28 L/min in continuous flow experiments, and sonicated at constant amplitude (20µmpeak-to-peak(p-p)). Ultrasonic batch experiments were conducted at varying amplitudes of 192-320µmp-p. After ultrasonication, StargenTM001 enzyme was added to the samples and a short 3h hydrolysis followed. The treated samples were found to yield 2-3 times more reducing sugar compared to the control (untreated) samples. In terms of energy density, the batch ultrasonic system was found to deliver 25-times more energy than the continuous flow systems. Although the experiments conducted in continuous system released less reducing sugar than the batch system, the continuous system was more energy efficient. The particle size of the sonicated corn slurry (both batch and continuous) was reduced relative to the controls (without treatment). The reduction of particle size was directly proportional to the energy input during sonication. The study suggests that both batch and continuous flow ultrasonic systems enhances enzymatic hydrolysis yield, reduces particle size of corn slurry and could be a potential effective pretreatment for corn slurry

Vibration Characteristics Determined for Stainless Steel Sandwich Panels With a Metal Foam Core for Lightweight Fan Blade Design

The goal of this project at the NASA Glenn Research Center is to provide fan materials that are safer, weigh less, and cost less than the currently used titanium alloy or polymer matrix composite fans. The proposed material system is a sandwich fan construction made up of thin solid face sheets and a lightweight metal foam core. The stiffness of the sandwich structure is increased by separating the two face sheets by the foam layer. The resulting structure has a high stiffness and lighter weight in comparison to the solid facesheet material alone. The face sheets carry the applied in-plane and bending loads (ref. 1). The metal foam core must resist the transverse shear and transverse normal loads, as well as keep the facings supported and working as a single unit. Metal foams have ranges of mechanical properties, such as light weight, impact resistance, and vibration suppression (ref. 2), which makes them more suitable for use in lightweight fan structures. Metal foams have been available for decades (refs. 3 and 4), but the difficulties in the original processes and high costs have prevented their widespread use. However, advances in production techniques and cost reduction have created a new interest in this class of materials (ref. 5). The material chosen for the face sheet and the metal foam for this study was the aerospace-grade stainless steel 17-4PH. This steel was chosen because of its attractive mechanical properties and the ease with which it can be made through the powder metallurgy process (ref. 6). The advantages of a metal foam core, in comparison to a typical honeycomb core, are material isotropy and the ease of forming complex geometries, such as fan blades. A section of a 17-4PH sandwich structure is shown in the following photograph. Part of process of designing any blade is to determine the natural frequencies of the particular blade shape. A designer needs to predict the resonance frequencies of a new blade design to properly identify a useful operating range. Operating a blade at or near the resonance frequencies leads to high-cycle fatigue, which ultimately limits the blade's durability and life. So the aim of this study is to determine the variation of the resonance frequencies for an idealized sandwich blade as a function of its face-sheet thickness, core thickness, and foam density. The finite element method is used to determine the natural frequencies for an idealized rectangular sandwich blade. The proven Lanczos method (ref. 7) is used in the study to extract the natural frequency

Analysis of Stainless Steel Sandwich Panels with a Metal Foam Care for Lightweight Fan Blade Design

The quest for cheap, low density and high performance materials in the design of aircraft and rotorcraft engine fan and propeller blades poses immense challenges to the materials and structural design engineers. Traditionally, these components have been fabricated using expensive materials such as light weight titanium alloys, polymeric composite materials and carbon-carbon composites. The present study investigates the use of P sandwich foam fan blade made up of solid face sheets and a metal foam core. The face sheets and the metal foam core material were an aerospace grade precipitation hardened 17-4 PH stainless steel with high strength and high toughness. The stiffness of the sandwich structure is increased by separating the two face sheets by a foam core. The resulting structure possesses a high stiffness while being lighter than a similar solid construction. Since the face sheets carry the applied bending loads, the sandwich architecture is a viable engineering concept. The material properties of 17-4 PH metal foam are reviewed briefly to describe the characteristics of the sandwich structure for a fan blade application. A vibration analysis for natural frequencies and P detailed stress analysis on the 17-4 PH sandwich foam blade design for different combinations of skin thickness and core volume %re presented with a comparison to a solid titanium blade