scholarly journals Optimising the Yield of Energy from Biomass by Analytical Models of the Rate of Growth

2010 ◽  
Vol 47 (5) ◽  
pp. 25-32 ◽  
Author(s):  
J. Abolins ◽  
J. Gravitis ◽  
J. Kosmacha
Keyword(s):  
Experimental Data ◽  
Growth Rate ◽  
Growth Rates ◽  
Standing Stock ◽  
Maximum Growth ◽  
Least Square ◽  
Analytical Models ◽  
Annual Increment ◽  
Mean Values ◽  
Rate Of Growth

Optimising the Yield of Energy from Biomass by Analytical Models of the Rate of Growth In the reported study of growth-rates of grey alder (Alnus incana) stands at different quality sites the authors, as a continuation of an earlier study, propose and use analytical models to approximate experimental data of mean annual increments of standing stock. The model equations of growth-rate functions are further used to optimise the cutting age by minimising the total area of stands for sustainable annual supply of biomass. The growth-rate behaviour with the age of natural grey alder stands is described by an exponential function of three parameters defining the initial and the maximum growth-rates, and the age at which the growth-rate maximum is reached. None of the parameters is known from experiment, and they are found by least-square fit of the available experimental mean values appraised at the chosen time intervals into the model. A high correlation between the experimental data and the model function is found. The optimum cutting age of 18 years determined in the earlier study is confirmed. In farmed stands the growth-rate is made to continue increasing at a lower speed, and is well approximated by a linear function, in which case it is shown that the cutting age cannot be optimised with respect to the area minimum existing under the condition of a decreasing growth-rate after passing a maximum. In the case of a constant or slowly growing annual increment the authors suggest considering the ratio between the increment of stock per unit of the total area to the increase in the area. The overall efficiency of using the product of photosynthesis for a 20-year-old grey alder stand is roughly estimated to be 0.3%.

A population birth-and-mutation process, I: explicit distributions for the number of mutants in an old culture of bacteria

1974 ◽  
Vol 11 (03) ◽  
pp. 437-444 ◽  
Author(s):  
Benoit Mandelbrot
Keyword(s):  
Growth Rate ◽  
Mutation Rate ◽  
Growth Rates ◽  
Random Variable ◽  
Mutation Process ◽  
Limit Condition ◽  
Rate Of Growth ◽  
Mathematical Techniques ◽  
First Time

Luria and Delbrück (1943) have observed that, in old cultures of bacteria that have mutated at random, the distribution of the number of mutants is extremely long-tailed. In this note, this distribution will be derived (for the first time) exactly and explicitly. The rates of mutation will be allowed to be either positive or infinitesimal, and the rate of growth for mutants will be allowed to be either equal, greater or smaller than for non-mutants. Under the realistic limit condition of a very low mutation rate, the number of mutants is shown to be a stable-Lévy (sometimes called “Pareto Lévy”) random variable, of maximum skewness ß, whose exponent α is essentially the ratio of the growth rates of non-mutants and of mutants. Thus, the probability of the number of mutants exceeding the very large value m is proportional to m –α–1 (a behavior sometimes referred to as “asymptotically Paretian” or “hyperbolic”). The unequal growth rate cases α ≠ 1 are solved for the first time. In the α = 1 case, a result of Lea and Coulson is rederived, interpreted, and generalized. Various paradoxes involving divergent moments that were encountered in earlier approaches are either absent or fully explainable. The mathematical techniques used being standard, they will not be described in detail, so this note will be primarily a collection of results. However, the justification for deriving them lies in their use in biology, and the mathematically unexperienced biologists may be unfamiliar with the tools used. They may wish for more details of calculations, more explanations and Figures. To satisfy their needs, a report available from the author upon request has been prepared. It will be referred to as Part II.

Reassessment of Maximum Growth Rates for C3 and C4 Crops

1978 ◽  
Vol 14 (1) ◽  
pp. 1-5 ◽  
Author(s):  
J. L. Monteith
Keyword(s):  
Growth Rate ◽  
Growth Rates ◽  
Growing Season ◽  
Maximum Growth ◽  
Maximum Growth Rate ◽  
Crop Growth ◽  
Close Inspection ◽  
Similar Difference ◽  
Photosynthetic Efficiencies

SUMMARYFigures for maximum crop growth rates, reviewed by Gifford (1974), suggest that the productivity of C3 and C4 species is almost indistinguishable. However, close inspection of these figures at source and correspondence with several authors revealed a number of errors. When all unreliable figures were discarded, the maximum growth rate for C3 stands fell in the range 34–39 g m−2 d−1 compared with 50–54 g m−2 d−1 for C4 stands. Maximum growth rates averaged over the whole growing season showed a similar difference: 13 g m−2 d−1 for C3 and 22 g m−2 d−1 for C4. These figures correspond to photosynthetic efficiencies of approximately 1·4 and 2·0%.

Interpretation of Experimental Data with Regard to the Activated Sludge Model No.1 and Calibration of the Model for Municipal Wastewater Treatment Plants

1992 ◽  
Vol 25 (6) ◽  
pp. 167-183 ◽  
Author(s):  
H. Siegrist ◽  
M. Tschui
Keyword(s):  
Experimental Data ◽  
Growth Rate ◽  
Activated Sludge ◽  
Municipal Wastewater ◽  
Wastewater Treatment Plants ◽  
Treatment Plant ◽  
Maximum Growth ◽  
Maximum Growth Rate ◽  
Municipal Wastewater Treatment ◽  
Activated Sludge Model

The wastewater of the municipal treatment plants Zürich-Werdhölzli (350000 population equivalents), Zürich-Glatt (110000), and Wattwil (20000) have been characterized with regard to the activated sludge model Nr.1 of the IAWPRC task group. Zürich-Glatt and Wattwil are partly nitrifying treatment plants and Zürich-Werdhölzli is fully nitrifying. The mixing characteristics of the aeration tanks at Werdhölzli and Glatt were determined with sodium bromide as a tracer. The experimental data were used to calibrate hydrolysis, heterotrophic growth and nitrification. Problems arising by calibrating hydrolysis of the paniculate material and by measuring oxygen consumption of heterotrophic and nitrifying microorganisms are discussed. For hydrolysis the experimental data indicate first-order kinetics. For nitrification a maximum growth rate of 0.40±0.07 d−1, corresponding to an observed growth rate of 0.26±0.04 d−1 was calculated at 10°C. The half velocity constant found for 12 and 20°C was 2 mg NH4-N/l. The calibrated model was verified with experimental dam of me Zürich-Werdhölzli treatment plant during ammonia shock load.

Single Crystal Silicon Carbide On Silicon Using A Supersonic Gas Jet Of Methylsilane

1997 ◽  
Vol 483 ◽  
Author(s):  
S. A. Ustin ◽  
C. Long ◽  
L. Lauhon ◽  
W. Ho
Keyword(s):  
Growth Rate ◽  
Growth Rates ◽  
Single Crystal Silicon ◽  
Maximum Growth ◽  
X Ray Diffraction ◽  
Crystal Silicon ◽  
Cross Sectional ◽  
Supersonic Molecular Beam ◽  
Transmission Electron

AbstractCubic SiC films have been grown on Si(001) and Si(111) substrates at temperatures between 600 °C and 900 °C with a single supersonic molecular beam source. Methylsilane (H3SiCH3) was used as the sole precursor with hydrogen and nitrogen as seeding gases. Optical reflectance was used to monitor in situ growth rate and macroscopic roughness. The growth rate of SiC was found to depend strongly on substrate orientation, methylsilane kinetic energy, and growth temperature. Growth rates were 1.5 to 2 times greater on Si(111) than on Si(001). The maximum growth rates achieved were 0.63 μm/hr on Si(111) and 0.375μm/hr on Si(001). Transmission electron diffraction (TED) and x-ray diffraction (XRD) were used for structural characterization. In-plane azimuthal (ø-) scans show that films on Si(001) have the correct 4-fold symmetry and that films on Si(111) have a 6-fold symmetry. The 6-fold symmetry indicates that stacking has occurred in two different sequences and double positioning boundaries have been formed. The minimum rocking curve width for SiC on Si(001) and Si(111) is 1.2°. Fourier Transform Infrared (FTIR) absorption was performed to discern the chemical bonding. Cross Sectional Transmission Electron Microscopy (XTEM) was used to image the SiC/Si interface.

The Relative Growth of Parts in Palaemon Carcinus

1930 ◽  
Vol 7 (2) ◽  
pp. 165-174
Author(s):  
M. A. TAZELAAR
Keyword(s):  
Growth Rate ◽  
Growth Rates ◽  
Linear Measurements ◽  
Relative Growth ◽  
Male And Female ◽  
Relative Growth Rates ◽  
Rate Of Growth ◽  
The Difference ◽  
Rates Of Growth

Linear measurements of certain appendages and the carapace of P. carcinus were made and plotted in various ways. The following conclusions were drawn: 1. The cheliped shows heterogonic growth in both male and female, but more markedly in the male, the values of k being: male 1.8 and female 1.48 2. The pereiopods in both male and female are slightly heterogonic. The relative growth rates are graded from p3 to p5, that of p3 being slightly greater than that of p5 3. Of the ordinary pereiopods the rate of growth of p1 is the smallest in the male, but the largest in the female. 4. The difference between the rates of growth of p1 and p3 in male and female is greatest where the rate of growth in the heterogonic organ, the cheliped, is most excessive in the male. 5. The growth of the 3rd maxilliped is slightly negatively heterogonic, the value of k in the male being 0.93 and in the female 0.95. Hence there seems to be a correlation between the marked heterogony in the cheliped on the growth rate of neighbouring appendages. In those immediately posterior to the cheliped the growth rate is increased and in those anterior decreased.

The evolution and bifurcation of a pendant drop

1994 ◽  
Vol 278 ◽  
pp. 83-100 ◽  
Author(s):  
R. M. S. M. Schulkes
Keyword(s):  
Experimental Data ◽  
Growth Rate ◽  
Satisfactory Agreement ◽  
Growth Rates ◽  
Pendant Drop ◽  
Large Growth ◽  
Comparison With Experimental Data

In this paper we calculate how a pendant drop evolves at the end of a nozzle when the volume of the drop increases steadily with time. We find that the character of the evolution is strongly dependent on the growth rate of the drop and the radius of the nozzle. Typically we find that once the drop has become unstable, two bifurcations occur shortly after each other when the growth rate of the drop is slow. For large growth rates the bifurcations are well-separated in time. We are able to calculate the volumes of the drops after the bifurcations. A comparison with experimental data shows a satisfactory agreement.

Kinetics And Morphology Of Homoepitaxial Cvd Growth On Diamond (100) And (111)

1995 ◽  
Vol 416 ◽  
Author(s):  
R. E. Rawles ◽  
W. G. Morris ◽  
M. P. D’Evelyn
Keyword(s):  
Growth Rate ◽  
Growth Rates ◽  
Chemical Vapor ◽  
Maximum Growth ◽  
Maximum Growth Rate ◽  
Arrhenius Behavior ◽  
Oriented Growth ◽  
Relative Growth Rates ◽  
Cvd Growth ◽  
Hot Filament

ABSTRACTGrowth rates for homoepitaxy of diamond (100) and (111) by hot-filament chemical vapor deposition were measured via in situ Fizeau interferometry and the surface morphologies were subsequently characterized by atomic force microscopy (AFM). (100)-oriented growth from 0.5% CH4 in H2 exhibited pure Arrhenius behavior, with an activation energy of 17±1 kcal/mol, up to a substrate temperature of 1100°C. Addition of oxygen to the feed gas resulted in an increased growth rate below 900°C, a maximum growth rate between 900 and 1000°C, and etching (of diamond) above 1050 - 1100°C. However, the presence of oxygen apparently had less effect on the surface morphology than did the (100)-to-(111) growth rate parameter α, determined directly from the relative growth rates of (100) and (111) substrates mounted side by side. During homoepitaxial growth from 0.5% CH4 in H2 at 875°C of ca. 1-micron-thick films,α = was 2.2 without oxygen and 1.3 for growth with 0.14% O2. The (100) film grown with α = 2.2 was quite smooth, while that with α = 1.3 was covered by numerous hillocks and penetration twins. AFM analysis revealed surprisingly little difference between the (111) films despite the considerable difference in α. Implications of these results for the growth mechanism are discussed.

scholarly journals A critical statistical study of experimental data on the effect of minute electric currents on the growth rate of the coleoptile of barley

1926 ◽  
Vol 99 (695) ◽  
pp. 122-130 ◽  
Keyword(s):  
Experimental Data ◽  
Growth Rate ◽  
Statistical Study ◽  
Pure Line ◽  
Similar Data ◽  
Electric Currents ◽  
Rate Of Growth ◽  
The Mean ◽  
Positive Results ◽  
Case Based

A study of the effect of very minute electric currents on the rate of growth of the coleoptile of barley was published recently by one of us (F. G. G.) in collaboration. In this paper the mean rate of a number of control coleoptiles was compared with the mean rate of a number exposed to a minute electric discharge. The growth rate of individual coleoptiles showed, naturally, considerable divergences, so the mean result was in each case based on the observation of a large number of coleoptiles, the increments of growth of individual coleoptiles being stated as percentages of the rate of growth during the first hour of observation. It was assumed that the distribution of growth rates in a comparatively large sample of a pure-line barley would conform with the normal distribution; the probable errors of the mean results were therefore calculated in the ordinary way. During the continuation of this work positive results have been obtained in further experimental sets, but a number of these, though significant in the mass, were individually without significance. This suggested that a careful statistical study of the data on which the results were based might show how the accuracy of the method could be increased. Such a study has accordingly been undertaken, and it seems probable that methods employed are likely to be of use in the treatment of similar data.

Relationship between growth rate and undercooling in Pt-added Y1Ba2Cu3O7−x

1996 ◽  
Vol 11 (5) ◽  
pp. 1114-1119 ◽  
Author(s):  
A. Endo ◽  
H. S. Chauhan ◽  
Y. Nakamura ◽  
Y. Shiohara
Keyword(s):  
Experimental Data ◽  
Growth Rate ◽  
Parabolic Equation ◽  
Growth Rates ◽  
Crystal Size ◽  
Experimental Conditions ◽  
Seed Crystals ◽  
Cooling Method ◽  
Increasing Trend ◽  
Good Agreement

Y1Ba2Cu307−x (Y123) crystals were grown by two different methods, the constant undercooling solidification and the continual cooling method, with top seeding by Sm123 seed crystals in order to investigate a relationship between undercooling (ΔT) and a growth rate (R). The crystals of Y123 with a sharp faceted interface, which consisted of {100} and {001} faces, grew epitaxially from the seed. It was found that the growth rates of {100} face (Ra) and that of {001} face (Rc) showed an increasing trend with increasing ΔT, and Rc was faster than Ra within these experimental conditions, ΔT < 20 K. The relation between R and ΔT follows the parabolic equation, viz. Ra ∝ ΔT1.9 and Rc ∝ ΔT1.3 for {100} and {001} faces, respectively. The simulated crystal size using the R and ΔT relations obtained from the constant undercooling method showed good agreement with experimental data by the continual cooling.

Growth Rate Responses of Lotic Periphytic Diatoms to Experimental Phosphorus Enrichment: The Influence of Temperature and Light

1988 ◽  
Vol 45 (2) ◽  
pp. 261-270 ◽  
Author(s):  
Max L. Bothwell
Keyword(s):  
Growth Rate ◽  
Growth Rates ◽  
Maximum Growth ◽  
Maximum Growth Rate ◽  
Phosphorus Enrichment ◽  
Enrichment Experiments ◽  
Community Growth ◽  
Specific Growth Rates ◽  
The Relationship ◽  
River Water Temperature

Phosphate enrichment experiments were conducted year-round at the experimental troughs research apparatus (EXTRA) on the South Thompson River in British Columbia to determine the relationship between external concentration of orthophosphate and the growth rates of lotic periphytic diatom communities. Growth rate saturation always occurred at a phosphate concentration of approximately 0.3–0.6 μg P∙L−1. The maximum growth rate (μmax-P) with phosphorus enrichment varied seasonally with temperature. The relative specific growth rates (μ:μmax-P) as a function of external phosphate were constant. Seasonal changes in solar insolation (PAR) had no effect on the autotrophic community growth rates in unamended river water. Temperature exerted the most dominant influence on phosphorus-replete growth rates.

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