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Strength and deformation modification factors of wood based composites for engineering design
This paper summarizes some of the findings from a comprehensive study concerning the performance of wood based composites in building construction. The presentation only focuses on the strength and deformation modification factors for engineering design of wood based composites, that is, i) to determine whether the strength and deformation modification factors (kmod and kdef ) in Eurocode 5 for formaldehyde based boards are applicable to boards manufactured using new alternative binders such as isocyanate and cement, ii) to evaluate the effect of long-term concentrated loading by a full scale component test and small-scale indicative test, and iii) to examine the effect of long-term shear loading (panel and planar shears) on the performance of wood based composites for structural uses in comparison with long term bending loading in Eurocodes 1 and 5. Numerous results and important findings showed that i) the kc and kd values of isocyanate bonded particleboard (PB) under bending loads were lower than those of formaldehyde based PB, the former being 70-80% the latter; ii) the kc of cement bonded particleboard (CBPB) were similar to that of formaldehyde based particleboards, but with the deflection of the former being about 1/5 the latter, the CBPB test pieces lasted much longer than MUFPB under duration of load tests; iii) stress modes had a significant effect on long term performance: The extrapolated kc values under concentrated load were generally higher than those under bending load and in EC5, depending on the type of materials and joint profiles, the extrapolated kd were very similar between concentrated and bending loads and in EC5, the extrapolated kd values under shear load were higher than those in EC5, however, the kc values varied considerably with the type of oriented strand boards (OSB) and medium density boards (MDF) under shear loading tests. The results clearly showed that there is a need for developing strength and deformation modification factors for new materials and materials under various stress modes for engineering designs
Lick Slit Spectra of Thirty-Eight Objective Prism QSO Candidates and Low Metallicity Halo Stars
We present Lick Observatory slit spectra of 38 objects which were claimed to
have pronounced ultraviolet excess and emission lines by Zhan \& Chen. Most of
our spectra have FWHM spectral resolutions of about 4~\AA , and relatively high
S/N of about 10 -- 50, although some have FWHM ~\AA ~or lower S/N.
We find eleven QSOs, four galaxies at , twenty-two stars and one
unidentified object with a low S/N spectrum. Six of the QSOs show absorption
systems, including Q0000+027A with a relatively strong associated C~IV
absorption system, and Q0008+008 (V) with a damped Ly
system with an H~I column density of cm. The stars include a
wide variety of spectral types. There is one new DA4 white dwarf at 170~pc, one
sdB at 14~kpc, and three M stars. The rest are of types F, G and K. We have
measured the equivalent widths of the Ca~II~K line, the G-band and the Balmer
lines in ten stars with the best spectra, and we derive metallicities. Seven of
them are in the range ~[Fe/H]~, while the others are less
metal poor. If the stars are dwarfs, then they are at distances of 1 to 7~kpc,
but if they are giants, typical distances will be about 10~kpc.Comment: (Plain Tex, 21 pages, including tables. Send email to
'travell_oir%[email protected]' for 12 pages of figures) To appear in the
%%Astronomical Journal, August, 199
Age-related deterioration of rod vision in mice
Even in healthy individuals, aging leads to deterioration in visual acuity, contrast sensitivity, visual field, and dark adaptation. Little is known about the neural mechanisms that drive the age-related changes of the retina and, more specifically, photoreceptors. According to one hypothesis, the age-related deterioration in rod function is due to the limited availability of 11-cis-retinal for rod pigment formation. To determine how aging affects rod photoreceptors and to test the retinoid-deficiency hypothesis, we compared the morphological and functional properties of rods of adult and aged B6D2F1/J mice. We found that the number of rods and the length of their outer segments were significantly reduced in 2.5-year-old mice compared with 4-month-old animals. Aging also resulted in a twofold reduction in the total level of opsin in the retina. Behavioral tests revealed that scotopic visual acuity and contrast sensitivity were decreased by twofold in aged mice, and rod ERG recordings demonstrated reduced amplitudes of both a- and b-waves. Sensitivity of aged rods determined from single-cell recordings was also decreased by 1.5-fold, corresponding to not more than 1% free opsin in these photoreceptors, and kinetic parameters of dim flash response were not altered. Notably, the rate of rod dark adaptation was unaffected by age. Thus, our results argue against age-related deficiency of 11-cis-retinal in the B6D2F1/J mouse rod visual cycle. Surprisingly, the level of cellular dark noise was increased in aged rods, providing an alternative mechanism for their desensitization
Employing per-component time step in DSMC simulations of disparate mass and cross-section gas mixtures
A new approach to simulation of stationary flows by Direct Simulation Monte
Carlo method is proposed. The idea is to specify an individual time step for
each component of a gas mixture. The approach consists of modifications mainly
to collision phase and recommendation on choosing time step ratios. It allows
softening the demands on the computational resources for cases of disparate
collision diameters of molecules and/or disparate molecular masses. These are
the cases important in vacuum deposition technologies. Few tests of the new
approach are made. Finally, the usage of new approach is demonstrated on a
problem of silver nanocluster diffusion in carrier gas argon in conditions of
silver deposition experiments.Comment: The goal of submission is to find native English speaker willing to
help me polish the paper. This is paper draft sent to Communications in
Computational Physics. It is recommended to publication. The need of
polishing was one of editors decision. See Additional data for MS Word source
fil
Three-dimensional metamaterials with an ultra-high effective refractive index over broad bandwidth
The authors introduce a general mechanism, based on electrostatic and
magnetostatic considerations, for designing three-dimensional isotopic
metamaterials that possess an enhanced refractive index over an extremely large
frequency range. The mechanism allows nearly independent control of effective
electric permittivity and magnetic permeability without the use of resonant
elements
Quantum Cloning of Mixed States in Symmetric Subspace
Quantum cloning machine for arbitrary mixed states in symmetric subspace is
proposed. This quantum cloning machine can be used to copy part of the output
state of another quantum cloning machine and is useful in quantum computation
and quantum information. The shrinking factor of this quantum cloning achieves
the well-known upper bound. When the input is identical pure states, two
different fidelities of this cloning machine are optimal.Comment: Revtex, 4 page
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