Propagation of transverse bulk and surface acoustic waves in LiNbO (3) variable time-delay devices

Experimental measurements are reported on voltage-controlled acoustic time-delay lines operating at 1 GHz in the nearly pure shear-horizontal (S-H) mode in 38 degrees rotated Y-cut LiNbO(3). The high-acoustic velocity (4800 m/s) in conjunction with the large electroacoustic effect exhibited by this orientation allows high-frequency operation and optimum time-delay tuning sensitivity with a planar, single surface, device geometry. The authors demonstrate fractional time delay of 0.3x10(-6) V(-1 ) for surface electrodes that produce an in-plane E-field. However, the simultaneous excitation and propagation of both a leaky surface-acoustic wave (LSAW) and surface skimming bulk wave (SSBW), both as (nearly pure) S-H waves in these devices, seriously restricts the extent to which it is possible to maximize the time delay modulation sensitivity by reducing electrode gap spacing as done in similar SAW devices. The LSAW and surface-skimming body wave (SSBW) propagate at nearly the same velocity on a free surface, and perturbation of their velocity and relative attenuation rates by surface electrodes causes pronounced interference effects between the two modes for some device geometries.     

High oil- and polyphenol-producing species of the northwest

The examination of plant species for their potential as renewable sources of industrial raw materials, conducted at the Northern Regional Research Center, has been extended to include 110 species from North Dakota (ND), Colorado (CO), and Oregon (OR), U.S.A. Plant samples were collected and analyzed for yields of “oil,” “polyphenol,” “hydrocarbon” and crude protein as well as for botanical characteristics. Data are presented only for the relatively high-yielding species. Oil and hydrocarbon extracts of plants that yielded at least 3.0% oil (dry, ash-free, plant sample basis) and/or at least 0.4% hydrocarbon were analyzed for classes of constituents. Oils of such species were saponified to determine yields of fatty acids and unsaponifiable matter. Hydrocarbon was examined for the presence of rubber, gutta and/or waxes. Polyisoprenes were analyzed for average molecular weight and molecular weight distribution. Even when compared to about 1000 species previously analyzed in this program, seven of the species yielded high amounts of oil (7.1–11.1%) plus substantial amounts of polyphenol (10.0–19.7%). Of these, six are evergreen trees or shrubs and one is a nonwoody perennial. Another seven species yielded substantial amounts of oil (5.4–6.6%), of which five gave 17.1–24.7% polyphenol. The most notable oil-producing species wereJuniperus scopulorum (11.1%),Pinus albicaulis (10.1%),Pinus flexilis (9.3%),Pinus mugo (8.4%),Liatris punctata (8.0%) andJuniperus communis (7.8%). Crude protein contents for all 22 species were low (4.2%) to moderate (10.4%). Maximum hydrocarbon content for the 22 selected species reported was only 0.5%. The highest total amount of oil, polyphenol, hydrocarbon and crude protein was 38.9% forAcer ginnala. Data obtained in this study are discussed with respect to those from species previously analyzed in this program.     

Anisotropic geodesics for live‐wire mesh segmentation

We present an interactive method for mesh segmentation that is inspired by the classical live‐wire interaction for image segmentation. The core contribution of the work is the definition and computation of wires on surfaces that are likely to lie at segment boundaries. We define wires as geodesics in a new tensor‐based anisotropic metric, which improves upon previous metrics in stability and feature‐awareness. We further introduce a simple but effective mesh embedding approach that allows geodesic paths in an anisotropic path to be computed efficiently using existing algorithms designed for Euclidean geodesics. Our tool is particularly suited for delineating segmentation boundaries that are aligned with features or curvature directions, and we demonstrate its use in creating artist‐guided segmentations.     

The effect of dyeing on the hygral expansion of worsted fabrics — Part 1

The influence of dyebath pH, dyeing time, levelling agents, dyestuff and anti-setting agent on hygral expansion has been investigated. The incorporation of an anti-setting agent in the dyebath minimised increases in hygral expansion resulting from the dyeing process.     

Hydrodynamics and mass transfer in a bubble column with an organic liquid

Hydrodynamic and mass transfer data in Soltrol-130 (a mixture of C₉+ iso-paraffins) were measured in a 0.305 m diameter bubble column. The gas holdup structure (i.e., the contributions to holdup from the small and large bubble fractions of the dispersion) for this hydrocarbon liquid in the churn turbulent flow regime was analyzed using the dynamic gas disengagement technique. The validity of the assumption of axially uniform gas holdup structure was checked. Literature correlations were found inadequate to explain the observed gas holdup and the volumetric mass transfer coefficients for Soltrol-130. The volumetric mass transfer coefficient per unit volume of large bubbles is shown to be independent of superficial gas velocity for the fully developed churn turbulent regime. The present hydrodynamic and mass transfer data in the churn turbulent regime should be useful in the design and scale-up of bubble columns used in organic process industries.     

Impact damage detection in carbon fibre composites using HTS SQUIDs and neural networks

A neural network-based data analysis tool, developed to speed the damage detection process for the NDE of impact damaged carbon fibre composites, is discussed. A feature extraction method utilising a gradient threshold search function and a feed forward neural network for pattern recognition were used to develop the system. Impact damaged carbon composite sample plates were scanned with an eddy current-based NDE setup using HTS SQUID gradiometers and double-D excitation coils. Detection of damage sites in data affected by noise spikes caused by environmental disturbances is demonstrated. Finally, a possible design for a future entirely automated scanning system is also introduced.     

Development of porous zirconia spheres by polymerization-induced colloid aggregation — effect of polymerization rate

Polymerization-induced colloid aggregation is used to synthesize spheres of narrow size distribution which are porous aggregates of ZrO₂ colloids. Variation of the reaction pH has been investigated to determine the optimum rate of polymerization of the urea-formaldehyde resin. At the optimum rate, a colloid packing structure is formed where a balance of high porosity and high strength of the aggregates is achieved. This optimum coincides with the maximum yield of the 5 m sintered (polymer-free) particles. Particles synthesized at pH values below the optimum are mechanically weak; some are hollow spheres. Variation of the pore structure, and thus colloid packing structure, is elucidated by nitrogen adsorption and apparent density measurements. Differences on either side of the optimum pH are related to the efficiency of polymer-bridge formation between colloids.     

The expanding small heat-shock protein family, and structure predictions of the conserved "alpha-crystallin domain"

The ever-increasing number of proteins identified as belonging to the family of small heat-shock proteins (shsps) and alpha-crystallins enables us to reassess the phylogeny of this ubiquitous protein family. While the prokaryotic and fungal representatives are not properly resolved, most of the plant and animal shsps and related proteins are clearly grouped in distinct clades, reflecting a history of repeated gene duplications. The members of the shsp family are characterized by the presence of a conserved homologous "alpha-crystallin domain," which sometimes is present in duplicate. Predictions are made of secondary structure and solvent accessibility of this domain, which together with hydropathy profiles and intron positions support the presence of two similar hydrophobic beta-sheet-rich motifs, connected by a hydrophilic alpha-helical region. Together with an overview of the newly characterized members of the shsp family, these data help to define this family as being involved as stable structural proteins and as molecular chaperones during normal development and induced under pathological and stressful conditions.