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  • 1
    Electronic Resource
    Electronic Resource
    A quantitative model of the ensilage process in lactate silages (1985)
    Oxford, UK : Blackwell Publishing Ltd
    Grass and forage science 40 (1985), S. 0 
    Details
    ISSN: 1365-2494
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: A model of the ensilage process is presented which can be used to predict silage quality in lactate silages. The model simulates the major microbial and biochemical processes during ensilage, including aerobic respiration, hydrolysis of hemicellulose. growth and death of lactic acid bacteria and their production of lactic and acetic acids, reduction in pH, change in soluble sugar content, increase in osmotic potential, and proteolysis. The model is designed to operate on mixtures of grasses, legumes, or whole-plant corn. Parameters for the model are developed from published silage experiments and pure-culture bacterial studies. The model gives reasonably accurate predictions of key silage quality parameters, but further experimental work is needed on growth of lactic acid bacteria and on plant-enzyme proteolysis. Predicted final pH depends primarily on the pH at which bacterial growth and death rates are equal. Initial bacterial concentration affects the time to rapid pH change, while maximum bacterial growth rate affects the rate of decline thereafter.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2494.1985.tb01755.x
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  • 2
    Electronic Resource
    Electronic Resource
    A model of aerobic fungal growth in silage. (1991)
    Oxford, UK : Blackwell Publishing Ltd
    Grass and forage science 46 (1991), S. 0 
    Details
    ISSN: 1365-2494
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: A simulation model of yeast and mould growth in aerobically deteriorating silage was tested and analysed. The model predictions of aerobic stability were compared with actual stability data from published experiments and were accurate when maize silage composition and initial yeast and mould counts were known. The time-course of deterioration was simulated for various initial temperatures and yeast and mould concentrations and exhibited primary, secondary, and tertiary heating in some cases; however, the model was limited in its ability to predict temperature history during deterioration because of the simplified treatment of heat transfer. In simulations, the relative importance of yeasts and moulds depended mainly on initial fungal concentrations, whereas the relative importance of mesophiles and thermophiles depended primarily on initial temperature. The model predicted that the period of silage aerobic stability ends when fungal concentrations reach approximately 0·001 g g−1 silage. Temperature, water-soluble carbohydrate concentration, fungal populations, and fermentation product concentrations in interaction with pH had the greatest direct effects on predicted aerobic stability. The model results suggest that aerobic stability is greatest when the pre-ensiling forage is highly buffered, of low dry matter content, and contains sufficient water-soluble carbohydrates to allow fermentation to the lowest possible pH with no residual water-soluble carbohydrates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2494.1991.tb02235.x
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  • 3
    Electronic Resource
    Electronic Resource
    A model of aerobic fungal growth in silage. (1991)
    Oxford, UK : Blackwell Publishing Ltd
    Grass and forage science 46 (1991), S. 0 
    Details
    ISSN: 1365-2494
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: The components of a simulation model of mesophilic and thermophilic yeast and mould growth in aerobically deteriorating silage are presented. The purpose of the model is to examine the relative roles of yeasts and moulds in deterioration and the factors affecting aerobic stability. Information for the model was based on literature studies. Growth of the fungi was assumed to be affected by temperature, pH, water activity, and lactic and acetic acid concentrations. The substrates utilized in the model, in order of preference, were water-soluble carbohydrates, ethanol, lactic acid and acetic acid. Gas movement and heat transfer were not considered. Consequently, oxygen and carbon dioxide concentrations were assumed to be those for open air, and the heat of respiration retained in the silage was set as a constant percentage of that released by fungal growth.Based on the relationships developed for the model, pH affects yeast growth minimally and does not affect mould growth at all. Water activity over the range in silage affects yeast growth more than mould growth, but affects neither one strongly. Undissociated lactic and acetic acids decrease growth rate and may be important factors in silage stability. Compared with moulds, yeast growth rates are less affected by suboptimum temperatures but are more sensitive to temperatures in excess of the optimum.A succeeding study compares the model with published aerobic deterioration studies and examines the predicted succession of microbial groups and the variation in silage stability as affected by silage parameters, initial temperature, and initial microbial populations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2494.1991.tb02234.x
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  • 4
    Electronic Resource
    Electronic Resource
    A model of clostridial dominance in ensilage (1987)
    Oxford, UK : Blackwell Publishing Ltd
    Grass and forage science 42 (1987), S. 0 
    Details
    ISSN: 1365-2494
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: A simulation model of the growth and fermentation of lactic acid bacteria and clostridia in silage is described. The model is used to predict the occurrence of a well-preserved lactate silage or a poorly-preserved clostridial silage. Results of the model are compared with published experimental studies not used in the model's development. The results are summarized with maps showing the combinations of initial water-soluble-carbohydrate content, crop buffering capacity, dry matter content, temperature, initial pH, and initial population of lactic acid bacteria which result in a clostridial silage. The specific processes modelled include the growth and death of lactic acid bacteria and clostridia; the use of substrate and accumulation of fermentation end products; release of ammonia; and change in silage pH.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2494.1987.tb02118.x
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  • 5
    Electronic Resource
    Electronic Resource
    Probability distributions for the strength of composite materials. III: The effect of fiber arrangement (1982)
    Springer
    International journal of fracture 20 (1982), S. 291-311 
    Details
    ISSN: 1573-2673
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Résumé Dans le mémoire, on poursuit l'étude du modèle de succession de bottes pour établir la résistance statistique des matériaux composites. On met ici l'accent sur les composites à trois dimensions ou les fibres suivant une section droite sont réparties sur deux dimensions. En particulier, on considère des rubans à deux dimensions et des regroupements en forme hexagonale et l'on obtient les distributions des liaisons en se basant sur l'apparition d'au moins deux ruptures de fibres adjacentes dans le matériau. Comme dans un travail précédent, il apparait diverses distributions de Weibull approximatives et limitatives pour exprimer la résistance du composite. En comparant les nouveaux résultats avec ceux obtenus précédemment dans le cas de rubans et de tubes (distribution à une dimension), l'approche utilisée suggère que la résistance médiane est modérément accrue dans le cas de distributions à deux dimensions, tandis que les variations de la contrainte sont inchangées. Dans des situations où l'apparition de deux ruptures de fibres adjacentes conduit presque certainement à la rupture du composite, de telles conclusions sont confirmées. Dans les cas où les liaisons sont clairement conservatives, on s'attend aux mêmes résultats, bien que puisse survenir une légère diminution dans la variabilité de la résistance du composite. Néanmoins, les liaisons envisagées dans ce mémoire présentent une importance considérable.
    Notes: Abstract This paper continues the study of the chain-of-bundles model for the statistical strength of composite materials. The focus is onthree-dimensional composites where the fibers in a cross-section form atwo-dimensional array. In particular, two-layer tapes and hexagonal arrays are considered, and bounding distributions are obtained based on the occurrence of at least two adjacent fiber fractures in the material. As in earlier work, various approximate and limiting Weibull distributions arise for the strength of the composite. In comparing the new results with those obtained earlier for tapes and tubes (one-dimensional arrays), the bounds suggest that the median strength is moderately increased for the two-dimensional arrays, while the variability in strength is unchanged. In situations where the occurrence of two adjacent fiber fractures leads almost certainly to composite fracture, such conclusions are warranted. In cases where the bounds are clearly conservative, the same results are expected, although a slight decrease in the variability in composite strength may occur. Nevertheless, the bounds discussed in this paper yield considerable insight.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01130614
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  • 6
    Electronic Resource
    Electronic Resource
    Probability distributions for the strength of composite materials IV: Localized load-sharing with tapering (1983)
    Springer
    International journal of fracture 22 (1983), S. 243-276 
    Details
    ISSN: 1573-2673
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Résumé Dans ce mémoire, on poursuit l'étude du modèle de groupage de bottes en série pour décrire la résistance statistique de matériaux composites, en se concentrant avec attention sur la redistribution locale des charges dans des composites à deux dimensions. On considère une règle plus souple pour le partage des contraintes, qui consiste à distribuer la charge nominale d'une fibre rompue sur les quatre fibres les plus proches, les deux fibres adjacentes absorbant la majeure partie de la charge. On considére trois techniques d'analyse probabiliste distinctes et on trouve que la structure probabiliste de base afférant à la distribution de la résistance dans le composite se présente comme la même que celle rencontrée lors du travail précédent où l'on étudiait un partage local idéalisé de la charge. Toutefois, la résistance médiane du composite s'accroit légèrement en raison de la surcharge moins sévère des fibres adjacentes à la rupture, tandis que la présence de faibles surcharges sur les fibres plus lointaines n'a pratiquement pas d'effet sur la résistance. En outre, la variation de résistance du composite tend à se réduire légèrement, vu le léger agrandissement de la zone sur laquelle se déroule la séquence critique des ruptures conduisant à rupture catastrophique. A nouveau, on constate que la distribution de Weibull apparait comme le modèle-clé pour décrire la résistance des composites unidirectionnels. Des approximations fiables de paramètres sont fournies.
    Notes: Abstract This paper continues the study of the chain-of-bundles model for the statistical strength of composite materials by focusing carefully on the localized load redistribution in two-dimensional composites. A tapered load-sharing rule is considered which distributes the nominal load of a failed fiber among its four nearest neighbors, with the two adjacent fibers taking a greater proportion of the load. We consider three distinct probabilistic techniques of analysis and find that the basic probability structure for the distribution for composite strength turns out to be the same as for the idealized local load-sharing in earlier work; however, the median strength of the composite rises moderately due to the milder overloads on the fibers adjacent to breaks, while the presence of small overloads on more distant fibers has almost no effect on strength. Also, the variability in composite strength tends to decrease mildly, due to a slight increase in the critical fracture sequence size leading to catastrophic failure. Again, the Weibull distribution arises as a key model for the strength of unidirectional composites, and we give accurate approximations for its parameters.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01140156
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  • 7
    Electronic Resource
    Electronic Resource
    Glycerol permeability of rye leaf protoplasts as affected by temperature and electroporation (1997)
    Springer
    Plant cell, tissue and organ culture 50 (1997), S. 215-219 
    Details
    ISSN: 1573-5044
    Keywords: activation energy ; electroporation ; glycerol ; permeability ; Secale cereale
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The permeability of rye leaf protoplasts to glycerol was determined using 1,3-14C glycerol and liquid scintillation spectrometry. Estimates were 1.0×10−8 m s−1 at 0°C and 4.1×10−8 m s−1 at 22 and 31°C. The activation energy for glycerol permeability was 32.8 kJ/mol. The effect of electroporation on glycerol uptake was also explored. Treatments were performed with a field strength of 100 V/cm and an exponential decay constant of 5.8 ms. At 22 °C, electroporation affected the rate and extent of glycerol permeation, causing an increase in the intercept of the glycerol uptake curve and a decrease in the slope. Electroporation had no significant effect on glycerol uptake when performed at 0°C, when the cells were electroporated at 0°C then warmed to 31 °C, or when the cells were electroporated at 22 °C then cooled to 0°C. The results at 22°C were consistent with an influx of glycerol during electroporation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005972908734
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  • 8
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    Coherent Regeneration ofKs'sby Carbon as a Test of Regge-Pole-Exchange Theory. (1977)
    American Physical Society
    Details
    Publication Date: 1977-09-05
    Print ISSN: 0031-9007
    Electronic ISSN: 1079-7114
    Topics: Physics
    Published by American Physical Society
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  • 9
    facet.materialart.
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    CoherentKSRegeneration on Protons from 30 to 130 GeV/c (1979)
    American Physical Society
    Details
    Publication Date: 1979-02-05
    Print ISSN: 0031-9007
    Electronic ISSN: 1079-7114
    Topics: Physics
    Published by American Physical Society
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  • 10
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    Inclusive Kaon Charge Exchange in the Triple-Regge Region at High Energies (1981)
    American Physical Society
    Details
    Publication Date: 1981-05-25
    Print ISSN: 0031-9007
    Electronic ISSN: 1079-7114
    Topics: Physics
    Published by American Physical Society
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