The use of forest-derived specific gravity for the conversion of volume to biomass for open-grown trees on agricultural land

Accounting for agroforestry contributions to carbon sequestration and cellulosic feedstock production requires biomass equations that accurately estimate biomass in open-grown trees. Since equations for open-grown trees are rare and developing these is expensive, existing forest-based equations are an attractive alternative for open-grown trees in carbon accounting and biomass modeling. How accurate this alternative is depends on how similar the key attributes, such as specific gravity, trunk shape, and crown architecture, are between open- and forest-grown trees. We evaluated the use of forest-derived specific gravity for conversion of volume to biomass for morphologically distinct open-grown species: green ash, ponderosa pine, and eastern redcedar. Trunk biomass was consistently and significantly underestimated from 6.3% to 16.6% depending on species, indicating open-grown trees have greater trunk specific gravity than forest-grown counterparts within the same geographic region; however a conclusive difference in branch specific gravity was not found between open- and forest-grown trees. Open-grown trees have greater trunk specific gravity, sharper trunk taper, and larger crown. When forest-based equations are used for trunk biomass of open-grown trees, the greater trunk specific gravity results in underestimation; however, the sharper trunk taper results in overestimation. Studies are needed to examine whether the underestimation could be offset by the overestimation and how the larger crown affects biomass estimation when forest-based equations are used for open-grown trees. Our results provide an essential understanding to interpret the biometric relationship of open- to forest-grown trees and to develop an efficient means how forest-based equations might be best modified for open-grown trees.     

Texture as the basis for individual tree identification

Recognizing plants from imagery is a complex task due to their irregular nature. In this research, three tree species, Japanese yew (Taxus cuspidata Sieb. & Zucc.), Hicks yew (Taxus x media), and eastern white pine (Pinus strobus L.), were identified using their textural properties. First, the plants were separated from their backgrounds in digital images based on a combination of textural features. Textural feature values for energy, local homogeneity, and inertia were derived from the co-occurrence matrix and differed significantly between the trees and their backgrounds. Subsequently, these features were used to construct the feature space where the nearest-neighbor method was applied to discriminate trees from their backgrounds. The recognition rates for Japanese yew, Hicks yew, and eastern white pine were 87%, 93%, and 93%, respectively. The study demonstrates that the texture features selected and the methods employed satisfactorily separated the trees from their relatively complex backgrounds and effectively differentiated between the three species. This research can lead to potentially useful applications in forestry and related disciplines.     

The preparation of large area films for bubble domain devices

The growth of LPE films 3.8 cm in diameter has been achieved under conditions which lead to a high yield of defect free material suitable for bubble domain circuits. Temperature control to ±0.1°C, larger melt volumes, more precise timing of runs and an increase in saturation temperature of the melt to 970°C all contribute to the improved quality. The change to 970°C also sharply reduces platinum attack. Films having a collapse field controlled to ±1 Oe can be grown in yields exceeding 35%.     

Rapid Prototyping for Pervasive Applications

VisualRDK is a high-level programming language for prototyping pervasive applications. Context is tightly integrated into the language itself, so developers can attach functionality to locations, persons, or situations instead of the device. Pervasive computing appliances range from consumer devices over embedded sensor boards to PCs and large-scale context servers. Because these devices vary tremendously in their capabilities, application developers must create different programming models for every class of device. This makes rapid prototyping infeasible as soon as more than one class of devices is involved. Rapid prototyping therefore requires a programming model that hides the environment's heterogeneity.     

Growth, optical properties, and CW laser action of neodymium-doped gadolinium scandium aluminum garnet

Investigation of the congruent melting rare-earth aluminum garnet Gd3Sc2Al3O12(GADSCAG) has been made. The optimum crystal growth parameters for the undoped material are a rotation rate of 20 r/min and a growth rate of 4.6 mm/hr along thelangle111rangledirection. For Nd³⁺-doped crystals the linear growth rate is 2 mm/h. The optical properties of Nd:GADSCAG which are of interest for laser operation were also determined. The stimulated emission cross section of the 1.06-μ transition in Nd³⁺at room temperature is(3.2 pm 0.3) times 10^{-19}cm², the fluorescence lifetime is256 pm 8 mus at an Nd³⁺ion density of 1 atomic percent in the crystal and the integrated peak absorption cross section in the strongest pump band (0.81 μ) is3.8 times 10^{-19}cm², A comparison of the CW laser performance of identical ND:YAG and Nd:GADSCAG rods is presented.     

YBa2Cu3O7 superconductors forhigh-speed interconnects

The surface resistance of high-quality YBa₂Cu₃ O₇ superconducting films measured over a frequency range from 10 to 500 GHz using high-speed optoelectronic techniques is discussed. A direct comparison is made with the surface resistance of gold and superconducting niobium conductors. Using the measured surface resistance, the propagation characteristic of interconnects based on YBa ₂Cu₃O₇ superconductors at 77 K is simulated and compared to that of gold transmission lines at 77 K and superconducting niobium lines at 7.7 K     

Highly Accurate Fiber-Optic DC Current Sensor for the Electrowinning Industry

A fiber-optic current sensor for direct currents up to 500 kA is presented. Applications include current measurement for process control and protection in the electrowinning industry, for example at aluminum smelters. The sensor offers significant advantages with regard to performance and ease of installation compared to state-of-the-art Hall-effect-based current transducers. The sensor exploits the Faraday effect in an optical fiber and measures the path integral of the magnetic field along a closed loop around the current-carrying bus bars. The differential magnetooptic phase shift of left and right circular light waves propagating in the fiber is detected by means of a novel polarization-rotated reflection interferometer. Fiber gyroscope technology is employed for signal detection and processing. The fiber is packaged in a flexible strip of fiber reinforced epoxy, which can be installed without opening the current-carrying bus bars. Subsequent recalibration is not necessary. The sensor achieves accuracy within plusmn0.1% over a wide range of currents and temperatures     

Magnetic moments for mixed substituted rare earth iron garnets

The molecular field coefficients for the individual rare earth iron garnets have been determined by a trial and error procedure using the phenomenological molecular field theory of Neél and the experimental curves for each rare-earth iron garnet. These results were then used to calculate magnetic moment-temperature curves for various film compositions subject to the conditions that the lattice parameter of the film and λ     

Temperature and vibration insensitive fiber-optic current sensor

A robust interferometric fiber-optic current sensor with inherent temperature compensation of the Faraday effect is presented. Sensor configurations based on Sagnac and polarization-rotated reflection interferometers are considered. The sensing fiber is residing and thermally annealed in a coiled capillary of fused silica. The capillary is embedded in silicone within a ring-shaped housing. It is theoretically and experimentally shown that the temperature dependence of the birefringent fiber-optic phase retarders of the interferometers can be employed to balance the temperature dependence of the Faraday effect (0.7×10^-4/°C). Insensitivity of the sensor to temperature within 0.2% is demonstrated between -35°C and 85°C. The influence of the phase retarders on the linearity of the sensor is also addressed. Furthermore, the sensitivity to vibration of the two configurations at frequencies up to 500 Hz and accelerations up to 10 g is compared. High immunity of the reflective sensor to mechanical perturbations is verified     

Stability of hydrogen in ScAlMgO4

Hydrogen as ²H was incorporated into ScAlMgO₄ by both ion implantation and by exposure to a plasma at 250°C. In the implanted material diffusion begins at 500°C and most of the hydrogen is lost by ≤ 750°C. This thermal stability for hydrogen retention is considerably lower than for other substrate materials for GaN epilayer growth, such as Al₂O₃ and SiC. There is minimal permeation of ²H from a plasma at 250°C (D_H ≤ 5 × 10⁻¹⁶ cm² s⁻¹) in ScAlMgO₄, and thus unintentional hydrogen incorporation into GaN overlayers should be minimal at typical growth temperatures.