Mean Form Factor Research Articles

Modeling a new taper curve and form factor of tree branches using terrestrial laser scanning

Abstract Modeling branch taper curve and form factor contributes to increasing the efficiency of tree crown reconstructions: the branch taper, defined as the sequential measure of diameters along the course of the branch, is pivotal to accurately estimate key branch variables such as biomass and volume. Branch diameters or volumes have commonly been estimated from terrestrial laser scanning (TLS) based on automatized voxelization or cylinder-fitting approaches, given the whole branch length is sufficiently covered by laser reflections. The results are, however, often affected by ample variations in point cloud characteristics caused by varying point density, occlusions, and noise. As these characteristics of TLS can hardly be sufficiently controlled or eliminated in automatized techniques, we proposed a new branch taper curve model and form factor, which can be employed directly from the laser reflections and under variable point cloud characteristics. In this paper, the approach is demonstrated on primary branches using a set of TLS-derived datasets from a sample of 20 trees (six species). The results showed an R2 of 0.86 and a mean relative absolute error of 1.03 cm (29%) when validated with field-measured diameters. The approach improved the accuracy of diameter estimates for the fine branch scales (<10 cm) as compared to the quantitative structural model (QSM). Our approach also allowed branch diameter estimation for a relatively larger number of manually recognized primary branches (>85%) from point clouds when validated with panoramic images acquired simultaneously with laser scanning. Frequently used automatized crown reconstructions from QSM, on the other hand, were affected by gaps in the point clouds due to obstruction, with the crown-tops and finer branches being the most critical. Our approach reports mean form factors across the examined species of 0.35 and 0.49, with the diameters determined at 5% and 10% of the total branch length, respectively. Our approach may have the potential to produce branch volume information with reasonable accuracy from only knowing the length and respective diameter of each branch. Our model delivers a first approximation for the taper curve and form factor for primary branches but was developed on a relatively small set of samples. We believe that our approach holds the potential to improve the accuracy of the assessment of branch diameter and volume from TLS data. The approach may also be extended to other branch orders. This could expand the horizon for volumetric calculations and biomass estimates from non-destructive TLS proxies in tree crowns.

Changes in the Diversity of Human Skin Microbiota to Cosmetic Serum Containing Prebiotics: Results from a Randomized Controlled Trial.

Prebiotic treatment may rebalance the skin microbiota by regulating the growth of harmful and beneficial microorganisms. In this randomized, double-blind, placebo-controlled clinical trial (N = 60), we evaluated the effects of a cosmetic serum containing galacto-oligosaccharides (GOS) on the balance of the skin microbiota by measuring various skin parameters. The skin water-holding capacity between the control (ND) and experimental (NF) groups was significantly different after 8 weeks of serum treatment (p < 0.05). Similarly, changes in transepidermal water loss (TEWL) and the erythema index in the ND and NF groups were significantly different (p < 0.05). Furthermore, the wrinkle depth and Staphylococcus aureus population decreased in the NF group compared with those in the ND group (p < 0.05). The mean form factor, Shannon index, and Pediococcus population were significantly increased in the post-NF group compared with those in the post-ND group (p < 0.05). Finally, in the ND group, water-holding capacity was positively correlated with Enhydrobacter, whereas Enterobacteriaceae was negatively correlated with TEWL in the NF group. These results suggest that GOS inhibit the growth of harmful skin microbes and increase the population of beneficial microbes.

Height, volume and form factor equations for Tectona grandis L.f. in Alta Floresta (MT)

Studies on allometric models are essential for quantifying the potential of a stand, especially when the objective is to know the wood stock through estimates. This study aimed to select height, volume and artificial form factor equations for a teak stand with data from a sample with 81 trees at 96 months in different diameter classes. The correlation analysis was performed between the variables total height, diameter with and without bark at 1.30 m soil height (dbhcc and dbhsc), total volume with and without bark (VTcc and VTsc) and artificial form factor with and without bark (ffcc and ffsc), using the Pearson coefficient. Six models were evaluated for each category: height, volume and artificial form factor, which were selected by the following criteria: analysis of variance, adjusted coefficient of determination, standard error of estimate, Akaike information criterion and graphical analysis of residues. The selected equations were validated by applying the L &amp; O test. The variables dbhcc, dbhsc, HT, VTcc and VTsc presented significant correlations, ranging from moderate to very strong, the others presented weak correlation. The model that presented the best relation of total height to diameter was the model of Azevedo and contributors. For the total volume with and without bark, Schumacher and Hall model in its logarithmic form was the one that presented the best results. The adjusted models for artificial form factor did not present satisfactory results and, therefore, the use of average form factor is recommended. The mean form factor values by diameter class ranged from 0.4498 to 0.7139 and 0.4480 to 0.7075 for diameter with and without bark, respectively.

Height and volume functions for Pinus lawsonii, Pinus leiophylla, Pinus oocarpa and Pinus pringlei plantations in Guarei, São Paulo, Brazil

Inventories are time- and money-consuming. Hence, accurate equations to estimate difficult-to-measure variables are desirable, especially for species that are not commercially established, such as Pinus lawsonii, P. leiophylla, P. pringlei and P. oocarpa. This study aimed to fit height and volume models for these species and to present stand attribute values for a plantation located in Guarei, Brazil, belonging to the company Resinas Brasil. Models were assessed by the adjusted coefficient of determination, mean square error and residual plots. For P. lawsonii and P. pringlei, the best hypsometric models were those of Van Soest and Mishailof, respectively. For P. leiophylla at 3 m × 1.5 m and 3 m × 3 m spacing, the best models were the linear and Mishailof models, respectively. For P. oocarpa planted at 3 m × 1.5 m and 3 m × 3 m spacing, the best models were those of Mishailof and Van Soest, respectively. The best volume model was the logarithmic Spurr for all species, except for P. oocarpa, where the Spurr model was the best. The mean stem form factor for all species was 0.53. Mean annual increment ranged from 8.4 to 24.5 m3 ha−1 (P. lawsonii and P. oocarpa), which can be considered satisfactory for plantations without genetic improvement and fertilisation, enforcing the species’ commercial potential.

Modeling and Biomass Quantification in Eucalyptus saligna Smith Stand at the End Rotation in the South of Brazil

The quantification of wood stock and other components of biomass is fundamental for forest planning. Given the difficulty of obtaining these data, the present study aims at the formulation of equations and the estimation of the different components of biomass, volume with and without bark, form factor and height of the trees at the end rotation. The study was carried out in the municipality of São Gabriel state of Rio Grande do Sul, Brazil with Eucalyptus saligna 10-year-old. The experimental design of the inventory and biomass quantification were completely randomized. In the inventory the DBH of all individuals of the 5 plots were measured. After determination of 4 classes of diameter were felled 12 trees and quantified leaves, branches, bark and wood. The selection of the models obtained coefficients of determination higher than 97%. The total biomass was 269 Mg ha-1, of which 89% was wood. The total volume was 546 and 494 m³ ha-1 with and without bark, representing an average annual increase of 54,6 and 49,4 m³ ha-1 year-1. The mean form factor was 0,48. The modeling presented excellent adjustments and certainly serves for future estimates of the stock biomass.

Form factors vs. regression models in volume estimation of Pinus taeda L. stem

Volume is an important information to know the available potential of a forest stand, although direct volume determination is expensive and often impractical. Thus, precise and accurate indirect methods are fundamental. Three volume estimation methods of Pinus taeda stem were compared: mean form factor, form factor by diameter class, and volume models fitted by regression. A total of 146 trees were used for this study, in which 96 were used for fitting and estimation, and 50 for validation, collected in the middle of the Parana State, Brazil. Fitting statistics (R 2 aj and Syx%) were used to evaluate regression models. Bias, precision and accuracy statistics, t-test and residue graphical analysis were used to judge estimation methods. Estimation by mean form factor (diameter class) and the Spurr model were equivalent, being superior to the others examined. It was concluded that the use of mean form factor by diameter class has satisfactory statistical performance, robustness and simplicity in volume estimation.

The characterization and quantitative analysis of nanopores in unconventional gas reservoirs utilizing FESEM–FIB and image processing: An example from the lower Silurian Longmaxi Shale, upper Yangtze region, China

In contrast to the millimeter-to-micron scale of pore systems found in conventional oil and gas reservoirs, unconventional oil and gas reservoirs have nanoscale pore systems. However, the methods used to characterize conventional reservoirs are not normally effective for studying nanopores. In the present study, a dual-beam field emission scanning microscope–focused ion beam (FESEM–FIB) device was used to investigate nanopores in a core plug sample of the Longmaxi Shale from Pengye Well #1, Chongqing, China. A large number of nanopores were observed, which can be divided into three types: intraparticle pores within mineral particles (intraP pores), interparticle pores between mineral particles (interP pores), and organic-matter pores (OM pores). The latter type is the most abundant. The Pores (Particles) and Cracks Analysis System (PCAS) was used to identify and analyze pores in high-resolution SEM images. The results show differences in pore size, pore area, probability entropy, form factor, and fractal dimension between the three pore types, especially between organic-matter pores and the other two pore types. The pore size of organic-matter pores ranges from 4 to 483nm (average 37nm), whereas the pore sizes of intraP pores and interP pores are 57–1136nm (average 210nm) and 31–1976nm (average 219nm), respectively. Results for pore area also reflect the smaller pore sizes of organic-matter pores. The probability entropy, mean form factor, and fractal dimension of organic-matter pores are 0.90, 0.72, and 1.08 respectively, suggesting disordered pore directions and limited morphological complexity. The form factor and fractal dimension of intraP and interP pores indicate more complex pore shapes for these pore types. InterP pores have more ordered alignments, as indicated by their lower probability entropy. Differences in matrix composition and/or the mode of occurrence of pores give rise to differences in pore size and shape.

Hartree-Fock Calculations of &amp;lt;sup&amp;gt;16&amp;lt;/sup&amp;gt;O and &amp;lt;sup&amp;gt;40&amp;lt;/sup&amp;gt;Ca Nuclei Using Fish-Bone Potential

Hartree-Fock calculations are carried out to describe some properties of 16O and 40Ca nuclei using the two forms of fish-bone potential (I and II). A computer simulation search program has been introduced to solve this problem. The Hilbert space was restricted to three dimensional variational space spanned by single spherical harmonic oscillator orbits. Binding energies, root mean square radii and form factors are found to have a good fit with experimental data.

Real Time Implementation of Multi Carrier Based PWM Techniques for Single Phase Nine Level Trinary Source CMLI Using dSPACE

Multi carrier based Pulse Width Modulation techniques have been implemented for switching of prototype of single phase trinary source cascaded multilevel inverter in which 9- level output voltage can be achieved with fewest components. Different species of Carrier Overlapping Pulse Width Modulation (COPWM-A, COPWM-B and COPWM –C) strategies along with trapezoidal reference are used. The gating pulses are generated using dSPACE dS1103 Real Time Interface (RTI) hardware and control desk with MATLAB- SIMULINK environment. It is observed that COPWM-A provides relatively lower THD. Relatively higher RMS output voltage for modulation index ma=0.8 to 1 is obtained with COPWM – B. The performance indices used are Total Harmonic Distortion (THD), Root Mean Square (RMS) output voltage, Crest Factor (CF),Form Factor (FF) and Distortion Factor (DF).

Anatomic Study of the Buccal Root with Furcation Groove and Associated Root Canal Shape in Maxillary First Premolars by Using Micro–Computed Tomography

IntroductionThe purpose of this study was to investigate the buccal root anatomy of bifurcated maxillary first premolars with furcation grooves and to determine the correlation between the groove depth and the buccal root canal shape by using micro–computed tomography. MethodsThirty-six bifurcated maxillary first premolars with furcation grooves were obtained from native Chinese individuals aged 17–25 years and scanned by micro–computed tomography. Basic parameters including the groove length, depth, and location were recorded. The wall thickness at different portions of the buccal roots was measured by using a customized application framework in MeVisLab software. The root canal shape was quantified by the form factor, and the correlation between the mean form factor and the maximum groove depth was analyzed. ResultsThe minimum wall thickness was less on the palatal aspect (<1 mm) than on the buccal aspect of the coronal two thirds of the buccal roots. The mean form factor value ranged from 0.72–0.91 and correlated negatively with the maximum groove depth (ρ2 = −0.641, P < .001). ConclusionsThe irregular wall thickness of buccal roots of bifurcated maxillary first premolars with furcation grooves and the related changes in the root canal shape should be considered during endodontic and prosthetic treatment.

Experimental and computational study of morphological and electrical properties of tin/plasma polymer nanocomposites

Composite tin/n-hexane plasma polymer films were prepared by means of RF magnetron sputtering of tin target in Ar:n-hexane mixture and characterised by various analytical techniques. Their chemical composition was examined by XPS, current-voltage characteristics were measured, and their structure was investigated by conventional TEM and electron tomography. The acquired three-dimensional reconstructions were morphologically analysed by a self-made computer analytical tool, which estimated the mean form factor and the average effective radius of the reconstructed metal inclusions.

Ambiguity in Determining the Shape of Alkali Alkyl Sulfate Micelles from Small-Angle Scattering Data

Model fitting to small-angle scattering patterns from a series of dilute sodium- and cesium alkyl sulfate micellar solutions results in two significantly different sets of best-fit parameters for each solution. One of the sets defines nearly monodisperse prolate ellipsoids; the other defines slightly, but significantly, polydisperse oblate ellipsoids. In the prolate and oblate minimum locations, the mean form and structure factors as well as the mean core volumes are equal within the experimental error such that the axial ratios are approximately the reciprocals of each other. The experimental finding is numerically generalized: it is demonstrated that, in a Q range, the upper limit of which depends on the axial ratio, the squared mean and the mean square of the scattering amplitude from homogeneous ellipsoids with equatorial radii and axial ratios, respectively (r,eta) and (reta2/3,1/eta), are indistinguishable in practice. In dilute solutions without added salt, neither the best-fit values of the model parameters nor the available thermodynamic models provide direct evidence for the conformation, although the prolate ellipsoidal shape is indirectly supported by experiment. The elongated conformation of ionic micelles in dense and/or salinated systems seems realistic.

Morphometric study of the apical anatomy of C‐shaped root canal systems in mandibular second molars

To investigate the apical anatomy of C-shaped canal systems in mandibular second molars by micro-computerized tomography (microCT) and stereomicroscopy. Forty-four permanent mandibular second molars with a C-shaped root canal systems from a native Chinese population were scanned at 100 microm intervals by microCT at a resolution of 30 x 30 microm. The apical 5 mm of each tooth was reconstructed three-dimensionally for visualization and classification of the canal configuration using Vertucci's criteria. The main and auxiliary (accessory) foramina were examined under a stereomicroscope. Type IV and VIII canal configurations were most often found in the apical 5 mm of these canal systems. The prevalence of accessory canals, lateral canals, inter-canal communications and apical delta were 41%, 25%, 27% and 11%, respectively. Approximately 80% of C-shaped canals had 1-3 apical foramina; the prevalence of accessory foramina was about 48%. The mean distance between the main foramen and the anatomic root apex was 0.84 mm, and that between the accessory foramen and the apex was 1.61 mm. The mean (shortest and longest) diameters of major and accessory foramina were 0.19 - 0.32 mm and 0.07 - 0.10 mm, with a mean form factor of 0.73 and 0.82, respectively. The apical anatomy of C-shaped root canal systems in mandibular second molars is extremely complex with many anatomical variations.

Predicting the onset of filamentous bulking in biological wastewater treatment systems by exploiting image analysis information

The performance of the activated sludge process is limited by the ability of the sedimentation tank (1) to separate the activated sludge from the treated effluent and (2) to concentrate it. Apart from bad operating strategies or poorly designed clarifiers, settling failures can mainly be attributed to filamentous bulking. Image analysis is a promising technique that can be used for early detection of filamentous bulking. The aim of this paper is therefore twofold. Foremost, correlations are sought between image analysis information (i.e., the total filament length per image, the mean form factor, the mean equivalent floc diameter, the mean floc roundness and the mean floc reduced radius of gyration) and classical measurements (i.e., the Sludge Volume Index (SVI)). Secondly, this information is both explored and exploited in order to identify dynamic ARX and state space-type models. Their performance is compared based on two criteria.

Identification and Modeling of the Sludge Volume Index by Exploiting Image Analysis Information

For many years now, activated sludge systems have been employed to treat a wide variety of wastewater. The system performance, however, is limited among other things by the failure of the sedimentation tank to separate and concentrate the activated sludge from the treated effluent. Filamentous bulking is one of the major problems encountered in activated sludge systems. Image analysis is a promising technique that can be used for early detection of filamentous bulking. The underlining aim of this work is twofold; (i) to seek correlations between image analysis information (e.g., the total filament length per image, the mean form factor, the mean equivalent floc diameter, the mean floc roundness, the mean floc reduced radius of gyration) and classical measurements (such as the Sludge Volume Index (SVI)) and, (ii) to both explore and exploit this information in order to identify dynamic ARX and state space type models whose performance is compared based on two criteria.

Empirical estimates of mean aortic pressure: advantages, drawbacks and implications for pressure redundancy.

Mean arterial pressure (MAP) is estimated at the brachial artery level by adding a fraction of pulse pressure (form factor; =0.33) to diastolic pressure. We tested the hypothesis that a fixed form factor can also be used at the aortic root level. We recorded systolic aortic pressure (SAP) and diastolic aortic pressure (DAP), and we calculated aortic pulse pressure (PP) and the time-averaged MAP in the aorta of resting adults (n=73; age 43+/-14 years). Wave reflection was quantified using the augmentation index. The aortic form factor (range 0.35-0.53) decreased with age, MAP, PP and augmentation index (each P<0.001). The mean form factor value (0.45) gave a reasonable estimation of MAP (MAP=DAP+0.45PP; bias=0+/-2 mmHg), and the bias increased with MAP (P<0.001). An alternative formula (MAP=DAP+PP/3+5 mmHg) gave a more precise estimation (bias=0+/-1 mmHg), and the bias was not related to MAP. This latter formula was consistent with the previously reported mean pulse wave amplification of 15 mmHg, and with unchanged MAP and diastolic pressure from aorta to periphery. Multiple linear regression showed that 99% of the variability of MAP was explained by the combined influence of DAP and SAP, thus confirming major pressure redundancy. Results were obtained irrespective of whether the marked differences in heart period and extent of wave reflection between subjects were taken into account. In conclusion, the aortic form factor was strongly influenced by age, aortic pressure and wave reflection. An empirical formula (MAP=DAP+PP/3+5 mmHg) that is consistent with mechanical principles in the arterial system gave a more precise estimate of MAP in the aorta of resting humans. Only two distinct pressure-powered functions were carried out in the (SAP, DAP, MAP, PP) four-pressure set.

Cocontinuous polymer blends: influence of viscosity and elasticity ratios of the constituent polymers on phase inversion

The morphological properties of melt-mixed blends with cocontinuous phase morphology composed of poly(methyl methacrylate) and polystyrene or poly(styrene–co–acrylonitrile) are studied. By means of digital image analysis of two-dimensional TEM pictures the mean form factor ffirr was established as a classificator. For 11 blend systems phase inversion concentrations were determined in this way.We studied the influence of viscosity and/or elasticity ratios on the phase inversion concentration. Most theories based on viscosity ratio disagree with our experimental data. The analysis of corresponding phase inversion concentrations based on elasticity ratio determined at a constant shear stress leads to a simple and good correlation.

Image analysis to estimate the settleability and concentration of activated sludge

A new method, using low magnification microscopy combined with image analysis to estimate settling properties of activated sludge, is presented. It is shown that the morphology of the activated sludge flocs correlates significantly with the settling properties of the sludge, as expressed by traditional settling tests. The morphology is expressed by two parameters: the mean equivalent circle diameter and the mean form factor of the sludge flocs. In contrast with traditional tests, the new method takes only between 10 and 20 min, is automated and can be incorporated in other sensors. In addition, a rapid and reliable estimate of the suspended solids concentration can be obtained by establishing a calibration between the mean field area of a series of images with the concentration of a certain type of activated sludge. The relevance of the novel method is clearly illustrated by its ability to monitor the rise and the subsequent cure of a severe case of bulking in an activated sludge pilot plant. It is shown that a more sensitive measurement of the sludge settleability is obtained by using image analysis. Consequently, the method presented may have good potential in being used as an early warning system.

Separation energy dependence of hole form factors

Abstract Form factors of fragmented hole states are studied within the quasiparticle-phonon model, using the inhomogeneous equation method. The validity of this method is successfully checked by comparison with coupled equation solutions in schematic vibrational model cases. A systematic investigation of form factors is performed for neutron and proton hole states in the valence and first inner shells of 208 Pb. Large fluctuations of form factor radii are observed for individual levels superimposed on a general increase with separation energy. Average characteristics are introduced for groups of levels, namely the mean form factors, summed source terms and correction potentials, and their behaviour is presented. The role of the relative values of the interaction radius parameter and binding well radius is discussed in detail.

Discrimination of benign versus malignant mixed tumors of the salivary gland using digital image analysis

Seven benign and four malignant mixed tumors of the salivary gland, biopsied using fine-needle aspiration, were analyzed using digital image analysis. Mean nuclear form factor, perimeter, and area were significantly increased in malignant cases. Better separation between diagnostic categories, however, was achieved by utilizing the coefficient of variation (CV) within a case rather than mean value. Form factor CV alone divided cases into nonoverlapping diagnostic categories. This quantitative analog of "pleomorphism" provided a useful marker for malignancy in mixed tumors.