A note on vowel centralization in stuttering and nonstuttering individuals

Inferences were made regarding vocal tract vowel space during fluently produced utterances through examination of the first two formant frequencies. Fifteen adult males served as subjects, representing separate groups of untreated and treated individuals who stutter and nonstuttering controls. The steady-state portion of formant one (F1) and formant two (F2) was examined in the production of various CVC tokens containing the vowels /i/, /u/, and /a/. Vocal tract vowel space was estimated three ways. The first analysis scheme involved measurement of formant frequency spacing. The second measure involved calculating the area of the vowel space triangle. The third measure was based on calculating the average Euclidean distance from each subject's midpoint "centroid" vocal tract position to the corresponding /i/, /u/, and /a/ points on the vowel triangle. The formant frequency spacing measures proved to be most revealing of group differences, with the untreated stutterers showing significantly greater vowel centralization than the treated group and control group. Discussion focuses on the vocal tract articulation characterizing fluent speech productions and possible treatment implications for persons who stutter.     

Low-friction carbon-rich carbide coatings deposited by co-sputtering

Low-friction coatings are used more and more frequently, particularly in situations and applications with insufficient or no lubrication. A good example of such coatings is amorphous carbon, which is produced both in pure form (a-C:H) and doped with metal (Me-C:H). The knowledge of what actually occurs when one metal in a Me-C:H coating is exchanged with another has so far been rather limited. Also, when producing these films hydrogen is incorporated in the substrate as well as in the film, which can be detrimental to the overall properties.Here, a newly adopted co-sputtering technique, utilizing a carbon target partly covered by metal-foil strips, was used to deposit non-hydrogenated carbon coatings alloyed with Ta, W and Zr on ball-bearing steel (BBS) substrates. The metal content varied between 0 and 41 at.%, and the resulting films were analyzed with respect to phase composition and textures, chemical composition, microstructural morphology, as well as mechanical and tribological properties. All alloyed coatings displayed a nanocomposite microstructure, with 3-6 nm metal-carbide crystallites embedded in a matrix of amorphous carbon. The amount of metal-carbide phase increased with increasing amounts of metal which led to a large increase in hardness and elastic modulus. An increased metal content did however not affect the carbide size to any notable extent. Ball-on-disk tests show that metal additions cause a sharp drop in friction coefficient from 0.21 to about 0.05, depending on the metal used. This is however accompanied by an increase in wear rate. The coating best combining low friction and low wear rate was alloyed with 20 at.% Ta. Best possible protection of the counter surface was offered by coatings containing 30 at.% Ta or more.     

Strain Localization in Sand: Plane Strain versus Triaxial Compression

A comprehensive experimental investigation was conducted to investigate the effects of loading condition and confining pressure on strength properties and localization phenomena in sands. A uniform subrounded to rounded natural silica sand known as F-75 Ottawa sand was used in the investigation. The results of a series on conventional triaxial compression (CTC) experiments tested under very low-confining pressures (0.05–1.30) kPa tested in a microgravity environment abroad the NASA Space Shuttle are presented in addition to the results of similar specimens tested in terrestrial laboratory to investigate the effect of confining pressure on the constitutive behavior of sands. The behavior of the CTC experiments is compared with the results of plane strain experiments. Computed tomography and other digital imaging techniques were used to study the development and evolution of shear bands.     

Color TV: total variation methods for restoration of vector-valuedimages

We propose a new definition of the total variation (TV) norm for vector-valued functions that can be applied to restore color and other vector-valued images. The new TV norm has the desirable properties of (1) not penalizing discontinuities (edges) in the image, (2) being rotationally invariant in the image space, and (3) reducing to the usual TV norm in the scalar case. Some numerical experiments on denoising simple color images in red-green-blue (RGB) color space are presented.     

Modelling of the Indoor Environment – Particle Dispersion and Deposition

Abstract A three-dimensional drift-flux model for particle movements in turbulent airflows in buildings is presented. The interaction between the carrier air and the particles has been treated as a one-way coupling, assuming the effect of particles on air turbulence is negligible due to low solid loadings and comparatively small particle settling velocities. Turbulence effects are modelled with a standard κ-? model. Wall functions are applied at near-wall grid points. Aerosol measurements carried out under turbulent room flow conditions are used to validate the numerical calculations. Several particle size distributions are considered in the simulations. The model is then applied to mixed flow conditions in a room, as well as to homogeneous air supply conditions around a human body. The flow fields and particle distributions are analysed. Close to a standing person, the particle distribution pattern from a downstream point source is strongly dependent on the ventilation air supply rate. This has been confirmed by experiments reported in the literature.     

Design and Construction of Shielded Lunar Outpost

The construction of an outpost on the Moon in which humans can live and work for periods exceeding six months will require special countermeasures to adapt to the hostile environment present at the lunar surface. Various inherent dangers such as meteoroids, galactic cosmic radiation, solar proton events, and large thermal extremes will drive the design configuration of the outpost. Other considerations such as lunar soil mechanics, equipment performance, mass delivery, risk, reliability, and tele‐operability act strongly as constraints that shape and control the design alternatives. Analysis of these fundamental relationships have resulted in lunar civil engineering guidelines, which are unique to this domain, and these in turn have pointed to research areas needing further attention. A preliminary design is presented for a lunar outpost shelter. Additionally, the design methodology is explored, and early enabling technologies are identified to facilitate an understanding of lunar shelter designs from an integrated system standpoint.