11,313 research outputs found
Eigenvalue extraction in NASTRAN by the tridiagonal reduction (FEER) method: Real eigenvalue analysis
The development of the tridiagonal reduction method and its implementation in NASTRAN are described for real eigenvalue analysis as typified by structural vibration and buckling problems. This method is an automatic matrix reduction scheme whereby the eigensolutions in the neighborhood of a specified point in the eigenspectrum can be accurately extracted from a tridiagonal eigenvalue problem whose order is much lower than that of the full problem. The process is effected without orbitrary lumping of masses or other physical quantities at selected node points and thus avoids one of the basic weaknesses of other techniques
Effects of extended grazing during mid, late or throughout pregnancy, and winter shearing of housed ewes, on ewe and lamb performance
peer-reviewedA flock of March-lambing ewes was used to evaluate the effects of (i) extended (deferred, winter) grazing of pasture during mid, late or throughout pregnancy, and (ii) winter shearing of ewes housed during mid and late pregnancy, on lamb birth weight and subsequent growth to weaning. Ewes (n = 265) were allocated at random to five treatments for the period from 7 December (~ day 47 of pregnancy) to lambing. The treatments were: housed shorn (HS), housed unshorn (HU), grazing throughout
(EG), grazing to 20 January followed by housing (EGH), housed to 20 January followed by grazing (HEG). From 1 March to lambing the HEG and EG ewes were dispersed on the paddocks intended for grazing post lambing. All ewes were offered a concentrate supplement during the final 6 weeks of pregnancy. Housed ewes were offered grass silage while ewes on extended grazing were allocated 1.3 kg herbage dry matter per head per day from swards that had been closed for approximately 10 weeks. Ewes plus lambs (except triplet-rearing ewes which were grazed separately) from all treatments were grazed together post lambing, grouped according to lambing date. For treatments HS, HU, EGH, HEG and EG gestation lengths were 147.0, 145.6, 146.3, 146.6 and 146.9 (s.e. 0.34, P < 0.001) days, lamb birth weights were 4.9, 4.3, 4.4, 4.6 and 5.0 (s.e. 0.10, P < 0.001) kg, and lamb weaning weights were 34.6, 32.1, 33.3, 33.8 and 34.9 (s.e. 0.66, P < 0.001) kg, respectively. Extended grazing in mid and late pregnancy resulted in 35% and 65%, respectively, of the increase in lamb birth weight associated with extended grazing throughout. Treatment effects on lamb birth weight were associated with those on weaning weight (P < 0.01, R2 = 0.93). It is concluded that extended grazing or shearing of housed ewes increased lamb birth weight and subsequent weaning weight. The increased lamb birth weight from deferred grazing in mid pregnancy was probably due to improved protein utilisation from the grazed herbage. Meanwhile, the increase
An evaluation of two grassland-based systems of mid-season prime lamb production using prolific ewes of two genotypes
peer-reviewedA 4-year study was undertaken to evaluate the effects of two contrasting management
systems [year-round grazing (YRG) and normal seasonal grazing followed by indoor
feeding during winter (GWF)] on performance of mid-season lambing ewes. On the
GWF system, the annual stocking rate was 14.4 ewes/ha, grass silage was conserved
for winter feeding indoors, and the ewes were lambed indoors and were then turned
out to pasture. The YRG system was stocked at 10.5 ewes/ha, was grazed during the
winter, had outdoor lambing and the animals had access to all the farmlet for summer
grazing. The ewes were Belclare and Cheviot × Belclare which were balanced
across systems. Mean lambing dates and fertiliser N application rates were 20 and 30
March, and 85 and 92 kg/ha, for the GWF and YRG systems, respectively. Concentrate
supplementation during late pregnancy was similar on both systems. For the GWF and
YRG systems, litter size, lamb mortality, number of lambs reared, birth weight (kg),
weaning weight (kg) and lamb carcass output (kg/ha) were 2.17 and 2.24 (s.e. 0.038),
10.1 and 13.8% (P = 0.05), 1.77 and 1.78 (s.e. 0.042), 4.0 and 4.7 (s.e. 0.05, P < 0.001),
27.9 and 30.8 (s.e. 0.25, P < 0.001) and 469 and 348, respectively. Belclare ewes had a
higher litter size (2.34 v 2.07; s.e. 0.038, P < 0.001) and number of lambs reared per
ewe joined (1.86 v 1.69; s.e. 0.048, P < 0.01) than the Cheviot × Belclare ewes. There
were no significant interactions between system and ewe breed type. It is concluded that
the YRG system of prime lamb production was sustainable using prolific ewes but at
a reduced stocking rate (−26%) and with greater lamb mortality relative to the GWF
system. Ewe genotypes with a mean litter size of up to 2.34 lambs are suitable for both
systems. Lamb carcass output of 501 kg/ha was achieved from a primarily grass-based
system of mid-season prime lamb production using prolific ewes (Belclare)
Perturbing forces in the lunar gravitational potential, part 3 Final report
Spherical harmonics for evaluating perturbing forces on lunar satellite due to nonsymmetric mass distribution of moo
RTCC requirements for mission G - Landing site determination using onboard observations, part 2 Final report
Computer programs for evaluation of telemetered rendezvous radar tracking data of orbiting command module and lunar module landing site determinatio
Minimum Distance Distribution of Irregular Generalized LDPC Code Ensembles
In this paper, the minimum distance distribution of irregular generalized
LDPC (GLDPC) code ensembles is investigated. Two classes of GLDPC code
ensembles are analyzed; in one case, the Tanner graph is regular from the
variable node perspective, and in the other case the Tanner graph is completely
unstructured and irregular. In particular, for the former ensemble class we
determine exactly which ensembles have minimum distance growing linearly with
the block length with probability approaching unity with increasing block
length. This work extends previous results concerning LDPC and regular GLDPC
codes to the case where a hybrid mixture of check node types is used.Comment: 5 pages, 1 figure. Submitted to the IEEE International Symposium on
Information Theory (ISIT) 201
Deep space network
Background, current status, and sites of Deep Space Network stations are briefly discussed
Recommended from our members
Parameter trails
Successful communication is vital for the success of any design project. However, communication often fails, adversely affecting design process efficiency and product quality.understand the connections between different aspects of design and don–t know where to find out more information or who to talk to. This paper presents a new model, developed from current project planning techniques, which supports communication using parameter-specific data. It enables designers to question information, inform their colleagues pro-actively and assess the impact of changing parameter values on subsequent design tasks. Such interaction is critical in allowing designers to see how their own tasks fit into the overall product design
Spectral Shape of Check-Hybrid GLDPC Codes
This paper analyzes the asymptotic exponent of both the weight spectrum and
the stopping set size spectrum for a class of generalized low-density
parity-check (GLDPC) codes. Specifically, all variable nodes (VNs) are assumed
to have the same degree (regular VN set), while the check node (CN) set is
assumed to be composed of a mixture of different linear block codes (hybrid CN
set). A simple expression for the exponent (which is also referred to as the
growth rate or the spectral shape) is developed. This expression is consistent
with previous results, including the case where the normalized weight or
stopping set size tends to zero. Furthermore, it is shown how certain symmetry
properties of the local weight distribution at the CNs induce a symmetry in the
overall weight spectral shape function.Comment: 6 pages, 3 figures. Presented at the IEEE ICC 2010, Cape Town, South
Africa. A minor typo in equation (9) has been correcte
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