Alternative equations to estimate the surface-to-volume ratio of different forest fuel particles

2011 ◽  
Vol 20 (5) ◽  
pp. 648 ◽  
Author(s):  
M. Hachmi ◽  
A. Sesbou ◽  
H. Benjelloun ◽  
F. Bouanane
Keyword(s):  
Cross Section ◽  
Estimation Method ◽  
Volume Ratio ◽  
Published Data ◽  
Fuel Type ◽  
Shrub Species ◽  
Elliptical Cross ◽  
Section Shape ◽  
Fuel Particles ◽  
Geometric Surface

Surface-to-volume ratio is an important fuel descriptor. Surface-to-volume ratio quantification methods currently used are specific and their accuracy varies with fuel types. In this work, we developed a geometric surface-to-volume ratio estimation method based on the perimeter-to-area ratio concept. Dimensions of leaves, twigs and needles of Moroccan tree and shrub species were measured. Our findings are: (i) the thickness of a leaf is variable along its width and length, and its average cross-section is located at its mid-length; (ii) a formula to calculate the ellipse perimeter was established using an elongation coefficient e, determined on the basis of the cross-section thickness and width; and (iii) one general surface-to-volume ratio formula was developed, from which five other equations were derived, according to the specific characteristics of each fuel type, for twigs, leaves, needles with semi-elliptical cross-section, needles with crescent cross-section shape, and needles with cross-section representing half or a sector of a circle respectively. Surface-to-volume ratio values obtained with the developed equations were compared with the currently published data.

scholarly journals Ultrafast Laser-Induced Crystallization of Lead Germanate Glass

Crystals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 193
Author(s):  
Sergey V. Lotarev ◽  
Alexey S. Lipatiev ◽  
Tatiana O. Lipateva ◽  
Elena V. Lopatina ◽  
Vladimir N. Sigaev
Keyword(s):  
Laser Beam ◽  
Cross Section ◽  
Direct Writing ◽  
Lead Germanate ◽  
Germanate Glass ◽  
Elliptical Cross ◽  
Selective Crystallization ◽  
Section Shape ◽  
Integrated Optical ◽  
Beam Parameters

Laser-induced space-selective crystallization of glass enabling the growth of continuous crystal-in-glass architectures consisting of non-centrosymmetric phases with functional properties is promising, including single-crystal waveguides for the development of integrated optical circuits. In this study, femtosecond laser direct writing of crystalline lines inside lead germanate glass with the composition close to Pb5Ge3O11 has been demonstrated. The growth of crystalline lines by the .moving focused laser beam required the preliminary growth of a seed crystal by the fixed beam. Confocal Raman spectroscopy revealed the precipitation of ferroelectric Pb5Ge3O11, which, under certain exposure conditions, could be accompanied by precipitation of the metastable lead germanate phase. Depending on the laser beam parameters, either bilateral growth providing split, horseshoe-shaped morphology of the crystal cross-section, or centered growth resulting in elongated, elliptical cross-section shape occurred. The obtained results are of interest for the fabrication of ferroelectric Pb5Ge3O11-based crystal-in-glass waveguides.

scholarly journals Influence of Cross-Sectional Shape on the Mechanical Properties of Concrete Canvas and CFRP-Reinforced Columns

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Jiangang Niu ◽  
Wenming Xu ◽  
Jingjun Li ◽  
Jian Liang
Keyword(s):  
Bearing Capacity ◽  
Axial Compression ◽  
Cross Section ◽  
Load Capacity ◽  
Fiber Reinforced Polymer ◽  
Strengthening Effect ◽  
Fiber Reinforced ◽  
Elliptical Cross ◽  
Reinforced Polymer ◽  
Section Shape

Fiber-reinforced polymer (FRP) wrapping has become an attractive strengthening technique for concrete columns. However, the ingress of corrosion into the concrete through the gap of CFRP fiber greatly reduces the durability of concrete and the bearing capacity of specimens. Concrete canvas, a kind of corrosion-resistant and refractory material, is a promising method to enhance durability and carrying capacity. In this study, the concrete canvas (CC) and carbon fiber-reinforced polymer (CFRP) were used to jointly reinforce columns with square cross section, octagonal cross section, circular cross section, and elliptical cross section. The influence of section shape on the strengthening effect of the axial compression column was investigated by the axial compression test. The results showed that the section shape had a significant influence on the reinforcement effect of the axial compression column. The carrying load capacity and ductility coefficient of different columns follow this order: square column < oval-shaped columns < octagonal columns < circle columns. The increased amplitude of bearing capacity for the different columns with the increase of CC layers follows this order: square columns < oval-shaped columns < circle column < octagonal columns. Compared with the unconstraint columns, the bearing capacity of adopting two-layer CC columns increased by 129%, 155%, 150%, and 139% for the square, octagonal, circular, and elliptical columns, respectively. The octagonal column has the largest increase range. Compared with the unconstraint columns, the bearing capacity of adopting two-layer CC columns increased by 348%, 318%, 310%, and 296% for the square, octagonal, elliptical, and circular columns, respectively. The square column has the largest increase range. The stress concentration phenomenon of all section shapes was weakened after the CC was used. The application of the CC on CFRP-reinforced columns improves column ductility significantly, with some degree of increase in bearing capacity.

scholarly journals Designing for People’s Safety on Flooded Streets: Uncertainties and the Influence of the Cross-Section Shape, Roughness and Slopes on Hazard Criteria

Water ◽  
2021 ◽  
Vol 13 (15) ◽  
pp. 2119
Author(s):  
Luís Mesquita David ◽  
Rita Fernandes de Carvalho
Keyword(s):  
Cross Section ◽  
Overland Flow ◽  
Rectangular Cross Section ◽  
Safety Hazard ◽  
Cross Section Shape ◽  
Section Shape ◽  
Flood Flows ◽  
The Cross ◽  
Flooding Risk

Designing for exceedance events consists in designing a continuous route for overland flow to deal with flows exceeding the sewer system’s capacity and to mitigate flooding risk. A review is carried out here on flood safety/hazard criteria, which generally establish thresholds for the water depth and flood velocity, or a relationship between them. The effects of the cross-section shape, roughness and slope of streets in meeting the criteria are evaluated based on equations, graphical results and one case study. An expedited method for the verification of safety criteria based solely on flow is presented, saving efforts in detailing models and increasing confidence in the results from simplified models. The method is valid for 0.1 m2/s 0.5 m2/s. The results showed that a street with a 1.8% slope, 75 m1/3s−1 and a rectangular cross-section complies with the threshold 0.3 m2/s for twice the flow of a street with the same width but with a conventional cross-section shape. The flow will be four times greater for a 15% street slope. The results also highlighted that the flood flows can vary significantly along the streets depending on the sewers’ roughness and the flow transfers between the major and minor systems, such that the effort detailing a street’s cross-section must be balanced with all of the other sources of uncertainty.

scholarly journals On the shape of cicada’s wing leading-edge cross section

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Rachel M. Starkweather ◽  
Svetlana V. Poroseva ◽  
David T. Hanson
Keyword(s):  
Cross Section ◽  
Insect Flight ◽  
Leading Edge ◽  
Flight Performance ◽  
Cross Section Shape ◽  
Section Shape ◽  
First Time

AbstractAn important role that the leading-edge cross-section shape plays in the wing flight performance is well known in aeronautics. However, little is known about the shape of the leading-edge cross section of an insect’s wing and its contribution to remarkable qualities of insect flight. In this paper, we reveal, in the first time, the shape of the leading-edge cross section of a cicada’s wing and analyze its variability along the wing. We also identify and quantify similarities in characteristic dimensions of this shape in the wings of three different cicada species.

Saint–Venant torsion of anisotropic elliptical bar

2017 ◽  
Vol 45 (3) ◽  
pp. 286-294 ◽  
Author(s):  
István Ecsedi ◽  
Attila Baksa
Keyword(s):  
General Solution ◽  
Cross Section ◽  
Elliptical Cross Section ◽  
Elliptical Cross

The object of this article is the Saint–Venant torsion of anisotropic, homogeneous bar with solid elliptical cross section. A general solution of the Saint–Venant torsion for anisotropic elliptical cross section is presented and some known results are reformulated. The case of non-warping cross section is analysed.

The need to complement in vitro gas production measurements with residue determinations from in sacco degradabilities to improve the prediction of voluntary intake of hays

1997 ◽  
Vol 64 (1) ◽  
pp. 71-75 ◽  
Author(s):  
M. Blümmel ◽  
P. Bullerdieck
Keyword(s):  
Volume Ratio ◽  
Gas Production ◽  
Published Data ◽  
Fatty Acid Production ◽  
Residue Determination ◽  
In Vitro Gas Production ◽  
Gas Volume ◽  
In Sacco Degradability ◽  
In Sacco

AbstractThe need to complement in vitro gas production measurements with residue determination is demonstrated by the recalculation and reassessment of published data on in vitro gas production, in sacco degradabilities and voluntary dry matter intake (DMI). The in sacco degradability — gas volume ratio was determined at 24 and 48 h of incubation, termed partitioning factor (PF) and combined with rate and extent parameters of in sacco degradability and in vitro gas production to predict DMI. In vitro gas production and in sacco degradability characteristics (a + b) and c as described by the equation y = a + b(1−ect) explained 0·373 and 0·668 respectively of the variation in DMI of 19 legume and grass hays. The complementation of gas production parameters by the PF24 increased the R2 value to 0·744 with PF24 accounting for 0·407 of the variation in DMI, the rate of gas production (c) for 0·218 and the extent of gas production (a + b) for 0·119 of the variation in DMI. As a single parameter, PF48 showed the highest correlation (R2 = 0·597) with DMI but the combination of PF4S with rate and extent of in sacco or in vitro gas production measurements did not improve the correlation further, probably due to an intercorrelation between rates of fermentation and PF4S. Hays which were degraded at faster rates had higher PF values indicating proportionally higher microbial yield and lower short-chain fatty acid production per unit substrate degraded. Generally, hays with high in sacco degradabilities but proportionally low gas production i.e. hays with high PF values showed higher DMI.

scholarly journals The Tidal Potential of a Homogeneous Torus with an Elliptical Section of the Sleeve

2016 ◽  
Vol 25 (3) ◽  
Author(s):  
B. P. Kondratyev ◽  
N. G. Trubitsyna
Keyword(s):  
Cross Section ◽  
Kuiper Belt ◽  
Analytical Form ◽  
Elliptical Cross Section ◽  
External Region ◽  
Elliptical Cross ◽  
Tidal Potential ◽  
Gravitational Model ◽  
Elliptical Section

AbstractIn this paper the problem of the tidal potential of a homogeneous gravitating torus with an elliptical cross-section sleeve is solved. In particular, the potentials in analytical form in the vicinity of the center of the torus and its external region are found. This torus can serve as a gravitational model of the Kuiper belt.

Oxidation of Suspended Stacked Silicon Nanowire for Sub-10nm Cross-Section Shape Optimization

2019 ◽  
Vol 13 (1) ◽  
pp. 195-199 ◽  
Author(s):  
Alexandre Hubert ◽  
Jean-Philippe Colonna ◽  
Stéphane Bécu ◽  
Cécilia Dupré ◽  
Virginie Maffini-Alvaro ◽  
...  
Keyword(s):  
Shape Optimization ◽  
Cross Section ◽  
Silicon Nanowire ◽  
Cross Section Shape ◽  
Section Shape
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