Real-time data compression of broadcast video signals

A non-adaptive predictor, a nonuniform quantizer, and a multi-level Huffman coder are incorporated into a differential pulse code modulation system for coding and decoding broadcast video signals in real time

Analysis of fluid/mechanical systems using EASY5

This paper illustrates how the use of a general analysis package can simplify modeling and analyzing fluid/mechanical systems. One such package is EASY5, a Boeing Computer Services product. The basic transmission line equations for modeling piped fluid systems are presented, as well as methods of incorporating these equations into the EASY5 environment. The paper describes how this analysis tool has been used to model several fluid subsystems of the Space Shuttle Orbiter

Methyl and t-butyl reorientation in an organic molecular solid

We have determined the molecular and crystal structure of 4,5-dibromo-2,7-di-t-butyl-9,9-dimethylxanthene and measured the 1H spin–lattice relaxation rate from 87 to 270 K at NMR frequencies of ω/2π=8.50, 22.5, and 53.0 MHz. All molecules in the crystal see the same intra and intermolecular environment and the repeating unit is half a molecule. We have extended models developed for 1H spin–lattice relaxation resulting from the reorientation of a t-butyl group and its constituent methyl groups to include these rotors and the 9-methyl groups. The relaxation rate data is well-fitted assuming that the t-butyl groups and all three of their constituent methyl groups, as well as the 9-methyl groups all reorient with an NMR activation energy of 15.8±1.6 kJ mol−1 corresponding to a barrier of 17.4±3.2 kJ mol−1. Only intramethyl and intra-t-butyl intermethyl spin–spin interactions need be considered. A unique random-motion Debye (or BPP) spectral density will not fit the data for any reasonable choice of parameters. A distribution of activation energies is required

Methyl and t-butyl reorientation in an organic molecular solid

We have determined the molecular and crystal structure of 4,5-dibromo-2,7-di-t-butyl-9,9-dimethylxanthene and measured the 1H spin–lattice relaxation rate from 87 to 270 K at NMR frequencies of ω/2π=8.50, 22.5, and 53.0 MHz. All molecules in the crystal see the same intra and intermolecular environment and the repeating unit is half a molecule. We have extended models developed for 1H spin–lattice relaxation resulting from the reorientation of a t-butyl group and its constituent methyl groups to include these rotors and the 9-methyl groups. The relaxation rate data is well-fitted assuming that the t-butyl groups and all three of their constituent methyl groups, as well as the 9-methyl groups all reorient with an NMR activation energy of 15.8±1.6 kJ mol−1 corresponding to a barrier of 17.4±3.2 kJ mol−1. Only intramethyl and intra-t-butyl intermethyl spin–spin interactions need be considered. A unique random-motion Debye (or BPP) spectral density will not fit the data for any reasonable choice of parameters. A distribution of activation energies is required

Improved Quantum Hard-Sphere Ground-State Equations of State

The London ground-state energy formula as a function of number density for a system of identical boson hard spheres, corrected for the reduced mass of a pair of particles in a sphere-of-influence picture, and generalized to fermion hard-sphere systems with two and four intrinsic degrees of freedom, has a double-pole at the ultimate \textit{regular} (or periodic, e.g., face-centered-cubic) close-packing density usually associated with a crystalline branch. Improved fluid branches are contructed based upon exact, field-theoretic perturbation-theory low-density expansions for many-boson and many-fermion systems, appropriately extrapolated to intermediate densities, but whose ultimate density is irregular or \textit{random} closest close-packing as suggested in studies of a classical system of hard spheres. Results show substantially improved agreement with the best available Green-function Monte Carlo and diffusion Monte Carlo simulations for bosons, as well as with ladder, variational Fermi hypernetted chain, and so-called L-expansion data for two-component fermions.Comment: 15 pages and 7 figure

Seasonal Survival and Cause-Specific Mortality of Northern Bobwhites in Mississippi

Knowledge of northern bobwhite (Colinus virginianus) survival and rates at which specific mortality agents remove individuals from the population is important for implementation of science-based harvest and habitat management regimes. To better understand population response to habitat management, we monitored 194 radio-marked northern bobwhites in managed old-field habitats in eastcentral Mississippi, 1993 to 1996. Bobwhite populations increased during the first 3 years following initiation of disking and burning practices. During the 2nd year of bobwhite habitat management breeding season survival (0.509) was high relative to other southeastern populations. However, breeding season survival declined from the 2nd through the 5th year of management (1993, 0.509; 1994, 0.362; 1995, 0.338; 1996, 0.167; P \u3c 0.001). Declining seasonal survival was attributable to increasing mammalian mortality from 1993 to 1996 (P \u3c 0.01). Avian mortality rates were stochastic and differed among years (P = 0.04), while unknown mortality rates were similar (P = 0.13). Avian mortality evidently operated in a density-dependent fashion, whereas mammalian mortality continued to increase despite declining bobwhite population. Northern bobwhite cause-specific mortality rates among years differed by sex (P \u3c 0.01) and age (P \u3c 0.01). Indices of breeding season relative abundance declined with declining survival. We hypothesize that manipulations (bum, disk, bum/disk) which created habitat that met the seasonal requirements of breeding bobwhites and other early successional prey species, may have resulted in a functional and numerical response of mammalian predators

Parrotts Creek Dredge Channel Data Report

Parrotts Creek is located along the Rappahannock River in Middlesex County, VA. The mouth of the creek is about 850 ft wide, but just inside the mouth of the creek, a spit extends from the upland narrowing the creek to about 300 ft before it widens again. Overall, this is a relatively short, undeveloped creek. Most of the development (wharfs, ramps, piers) occur near the mouth. Most of the more inland areas of the creek are surrounded by woodland. The federally-authorized channel was established in 1955 due to the presence of a public ramp and landing area, as well as oyster and seafood packing houses located on the creek. It is a 4,800 ft long, 60 ft wide channel with a 120 ft by 120 ft turning basin, and a controlling depth of -6 ft MLLW. (...

Comments on Closed Bianchi Models

We show several kinematical properties that are intrinsic to the Bianchi models with compact spatial sections. Especially, with spacelike hypersurfaces being closed, (A) no anisotropic expansion is allowed for Bianchi type V and VII(A\not=0), and (B) type IV and VI(A\not=0,1) does not exist. In order to show them, we put into geometric terms what is meant by spatial homogeneity and employ a mathematical result on 3-manifolds. We make clear the relation between the Bianchi type symmetry of space-time and spatial compactness, some part of which seem to be unnoticed in the literature. Especially, it is shown under what conditions class B Bianchi models do not possess compact spatial sections. Finally we briefly describe how this study is useful in investigating global dynamics in (3+1)-dimensional gravity.Comment: 14 pages with one table, KUCP-5

Town of Colonial Beach Survey of Central and Castlewood Beaches

The Town of Colonial Beach occupies a peninsula between the Potomac River and Monroe Bay. Approximately 2.5 miles of the shoreline is publicly-owned. Two areas on the Potomac River have been enhanced as recreational beaches for swimming and sunbathing. Central Beach is located just south of the Town Pier and is the main recreational beach. Castlewood Beach is south of Central Beach near the entrance to Monroe Bay

Performance of Sills: St. Mary’s City, St. Mary’s River, Maryland

Living shorelines represent a shoreline management option that combines various erosion control methodologies and/or structures while at the same time restoring or preserving natural shoreline vegetation communities. A common living shoreline design in Chesapeake Bay includes a low offshore rock sill to absorb wave energy with an emergent wetland landward of the sill to enhance erosion control, provide critical habitat, and improve water quality condition. This study is part of a larger, ongoing project to (1) evaluate erosion control effectiveness and the sustainability of offshore sill and fringing marsh design and structure, (2) evaluate ecological services (e.g., habitat value, water quality remediation) provided by the various components of the living shoreline design, and (3) develop design criteria that may enhance services provided by living shoreline designs in low and moderate energy environments. This project measures the performance of sills in Chesapeake Bay in support of developing design guidance. In particular, it assesses how the windows (or gaps/vents) in some sills affect their value for shore protection and water quality. The approach utilizes both field data collection (e.g., site assessment and survey, water quality data collection) and hydrodynamic modeling methodology. Two sites, varying in construction design and age, were assessed at St. Mary’s City, Maryland on the St. Mary’s River (Figure 1-1). Site 1 is part of a larger project and has about 1,000 feet of shoreline with a gapped sill that was built in 2002 (Figure 1-2). Site 2, a 1,000 feet non-gapped sill, was built in 1998 and is adjacent to Site 1 (Figure 1-2). Previous data exists for Site 1, which includes the implemented construction plan and the as-built survey. Both sites were surveyed to provide the present dimensions of the sill systems. Modeling methodology was used to assess residence time and age of water that flushes through sill structures and associated fringing wetland along part of Site 1. Also analyzed was the impact of several different window configurations and dimensions on beach shape and shore protection as well as the site substrate and vegetation characteristics, surface water and groundwater quality, and nekton