Flexibility Coefficients Research Articles

Suitability of Four Varieties of Cocos Nucifera Husk in Ghana for Pulp and Paper Production

ABSTRACT Research by the paper industry into new materials to expand the raw material base for pulp is on the ascendancy due to growing demand for pulp and paper products. This study assessed the anatomical, chemical, and pulping characteristics of four varieties of Cocos nucifera husk to ascertain their suitability as raw material for pulp and paper production. The measured and calculated chemical (Klason Lignin, 1% NaOH solubility and Holocellulose contents) and anatomical (Fiber dimensions, Runkel Ratio, Slenderness Ratio, Flexibility Coefficient, Coefficient of Rigidity, Luce’s Shape Factor and Solids Factor) properties of the Cocos nucifera husks mostly did not meet the standard requirements for a good pulp and paper material. However, the Local Tall Yellow variety of the Cocos nucifera husk was favorable in terms of Runkel Ratio, Slenderness Ratio, Flexibility Coefficient, and Coefficient of Rigidity and can be considered for the production of pulp for writing and printing papers. In spite of the limitations of the other three varieties for making quality paper, they could be used for fiber plate, rigid cardboard, and cardboard production.

Assessment of the papermaking potential of processed Miscanthus × giganteus stalks using alkaline pre-treatment and hydrodynamic cavitation for delignification

One way of satisfying increased market demand and simultaneously achieving a reduced environmental load in the industrial paper production is the use of fibrous agricultural residues. The aims of this study were i) to investigate the effect of alkaline – hydrodynamic cavitation (HC) pre-treatments on the delignification of Miscanthus × giganteus stalks (MGS) and ii) establishing the suitability of MGS as feedstock and their exploitation in pulp and paper manufacturing. It was demonstrated that the proposed treatment is an efficient delignification method for the non-wood fiber sources, such as miscanthus. A significant outcome of this work was the observation that HC treatment preserved the fibres lengths and surface quality of raw MGS, but at the same time increased the amount of kinked and curled fibers present in cavitated miscanthus fibers. The average miscanthus fiber length was found to be relatively short at 0.45 (±0.28) mm, while the slenderness ratio, the flexibility coefficient and Runkel ratio values were calculated to be 28.13, 38.16 and 1.62, respectively. The estimated physical properties of MGS pulp hand-sheets were 24.88 (±3.09) N m g−1 as the tensile index, 0.92 (±0.06) kPa m2 g−1 as the burst index and 4.0 (±0.37) mN m2 g−1 as the tear index. Overall the current work demonstrated effective use of hydrodynamic cavitation for improving the processing in pulp and paper manufacturing.

Development of Track Superelevation Simulation Testing System

This paper first discusses the standard requirements and the existing test method for the coefficient of flexibility of the existing metro vehicle. The existing method has the disadvantages of manpower cost, insufficient accuracy of track lifting, different lifting speed of jacks under axle boxes. There are also safety hazards of the vehicle capsizing and the jack sliding. This paper introduces a set of simulation testing system based on hydraulic principle for these problems, measuring track superelevation accurately, reading and controlling the height of vehicle body and the track, thus realizing measuring the coefficient of flexibility. This system has the advantages of simple structure, easy installation, convenient operation and high measuring precision. The track distance, wheelbase and biaxial distance are all variable. It also saves manpower and effectively eliminate safety hazards.

On non-axisymmetric buckling modes of inhomogeneous circular plates

Unsymmetrical buckling of nonuniform circular plates with elastically restrained edge and subjected to normal pressure is studied in this paper. The asymmetric part of the solution is sought in terms of multiples of the harmonics of the angular coordinate. A numerical method is employed to obtain the lowest load value at which waves in the circumferential direction can appear. The effect of material heterogeneity and boundary on the buckling load is examined. For a plate with elastically restrained edge, the buckling pressure and mode number increase with a rise of spring stiffness. Increasing of the elasticity modulus to the plate edge leads to increasing of the buckling pressure, but the mode number does not change. If the translational flexibility coefficient is small, decreasing of the elasticity modulus to the shell (plate) edge leads to sufficient lowering of the buckling pressure.

The Economics of Blockchain-Based Virtual Worlds: A Hedonic Regression Model for Virtual Land

Virtual worlds have become increasingly more important, and are being used for a large variety of recreational and business activities. Various companies have opened virtual offices and brand ambassador spaces, and the recent surge in online interactions has further increased the interest in these social platforms. In this paper, we analyze the first large-scale virtual world that has been built on a public blockchain network. We compile a comprehensive data set that allows us to study the economics of blockchain-based virtual property. We then use this data set to estimate hedonic regression models for virtual land and employ a semi-parametric Mixed Geographically Weighted Regression (MGWR) model that allows for spatially flexible coefficients. In particular, we expect the central business district (CBD) gradient and the street distance coefficients to vary across the virtual world. Conversely, we consider the coefficients of binary variables to be more meaningful in a global context. For inference purposes, we employ spatial robust heteroskedasticity and autocorrelation consistent (HAC) standard errors. We find evidence that prices of virtual land parcels are primarily driven by factors that are of particular importance in business applications. Land parcels in close proximity to popular landmarks, such as the city center, main streets, plazas and commercially-driven districts, as well as parcels with easily memorable address-like features were claimed at substantially higher prices. We used different model specifications and conducted various robustness checks, including a separate estimation for price segments and investor-specific effects. All specifications have led to similar results and support the evidence from our MGWR model.

Selection of Eucalyptus camaldulensis Families for Sustainable Pulpwood Production by Means of Anatomical Characteristics

Sustainable pulpwood production from fast-growing tree plantations is needed for pulp and paper industries. To increase the pulpwood production efficiency, the anatomical characteristics and derived-wood properties of 75 trees from 15 half-sib families of Eucalyptus camaldulensis Dehnh. planted in Thailand were investigated, and then the family was classified by suitability of wood as raw material for pulp and paper products using principal component analysis and clustering. The mean values of vessel diameter, vessel frequency, fibre diameter, fibre lumen diameter, and fibre wall thickness at 2 cm from the cambium were 128 µm, 16 no./mm2, 11.1 µm, 7.1 µm, and 1.88 µm, respectively. In addition, the Runkel ratio, Luce’s shape factor, flexibility coefficient, slenderness ratio, solids factor, and wall coverage ratio (i.e., derived-wood properties) were 0.53, 0.42, 0.64, 85.3, 68 × 103 µm3, and 0.34, respectively. Significant differences in fibre diameter, fibre lumen diameter, and Runkel ratio were found among families. Although significant differences among families were not found for other anatomical characteristics and derived-wood properties, the p-values obtained by an analysis of variance test ranged from 0.050 to 0.088. Based on the results of a principal component analysis and cluster analysis, 15 families were classified into four clusters with different expected pulp and paper characteristics. The suitability of wood from E. camaldulensis half-sib families for pulp and paper can be evaluated by principal component analysis using anatomical characteristics and physical properties as variables. Based on the results, desirable pulp and paper quality may be obtained through the selection of families from this species.

Caracterización estructural, física y química de la fibra de rastrojo de la cosecha de piña (ananas comosus) golden como alternativa para elaborar papel

El artículo presenta los resultados obtenidos en la caracterización estructural, física y química de la fibra de rastrojo de la cosecha de piña (Ananas Comosus) Golden como alternativa para elaborar papel, Se determinaron las propiedades biométricas de las fibras (longitud y diámetro, grosor de la pared y diámetro del lumen), para luego obtener los índices de calidad de pulpa para papel, como también se analizaron los porcentajes de celulosa, Holocelulosa y lignina, según las Normas TAPPI para cada componente y el método de Jayme-Wise. Este estudio se hizo con la finalidad de tener información para su posterior aprovechamiento en la industria de pulpa y papel. Las muestras de los rastrojos de piña fueron extraídas del centro poblado de Omaya, Pichari del Valle de los ríos Apurímac, Ene y Mantaro (VRAEM)- Perú. Los resultados indican que presentan medidas biométricas de: Longitud de la fibra: 1105 µm, Grosor de la pared: 2,75 µm, Ancho de la fibra: 20,0625 µm, Diámetro de Lumen: 5,35 µm, que esta materia prima es apta para producir papel de calidad regular presentando un coeficiente de Runkel de 1,028, un coeficiente de flexibilidad de 0,27 y un coeficiente de rigidez de 0,27; Según sus características químicas la fibra de hojas de piña Golden presenta un bajo contenido de lignina siendo el 12,335 %, Holocelulosa 41,72 % y un alto contenido de celulosa 44,04 % siendo un material potencial en la industria de pulpa y papel.

Numerical analysis of methods for calculating the soil base and methods for determining bed coefficients

Despite significant progress in the development of methods for calculating the soil base in a single calculation model with structures and the ability to perform calculations in three dimensions, the most popular in the community of design engineers remains the calculation model of the slab on an elastic basis. This is due to the simplicity of such a model. Probably, the greatest difficulty in applying such a model is to determine the coefficients of flexibility of the base (bed coefficients).
 In this paper, a study of the reliability of different methods for determining the coefficients of the bed under different variants of soil conditions
 The paper determines and compares the characteristics of the stress-strain state (sedimentation values, reactive pressure and forces) in three foundation slabs of different geometry and under different engineering and geological conditions of the construction site.
 A homogeneous base composed of loess soils, an inhomogeneous base composed of alternating layers of both cohesive (loam and sand) and incoherent (fine sand) soils and a close to homogeneous base composed of sand and soils are considered.
 The research was conducted using the software and computer system LIRA SAPR 2016. Implemented three methods for determining the coefficients of the bed (the flexibility of the base):
 - Pasternak model with two bed coefficients, which for inhomogeneous soils are determined by the values of the deformation modulus and Poisson's ratio averaged within the depth of the compressible thickness;
 - Winkler model with one bed ratio;
 - Pasternak model with two bed coefficients, which are determined by the average values of the deformation modulus and Poisson's ratio when introducing the correction factor to the deformation modulus.
 The convergence of the absolute values of the controlled parameters obtained using the above methods, depending on the type of soil base and the nature of soil layers within the compressible layer, is analyzed.
 The dependence of the convergence of the characteristics of the stress-strain state of the slab obtained by different methods on the homogeneity of the base soils is established.

Potencial da madeira de Pinus glabra para produção de polpa celulósica

Há mais de um século as espécies de Pinus estão presentes no Brasil, com destaque para o Pinus taeda, com aplicações em diversos setores. Entretanto o Pinus glabra, objeto deste estudo, não conta com muitas informações sobre o potencial tecnológico de sua madeira. Assim o objetivo do estudo é inferir sobre a qualidade da madeira do P. glabra para produção de polpa celulósica, comparando-a ao P. taeda, principal espécie empregada para fabricação de polpa celulósica de fibra longa no Brasil. Para isso foram abatidas quatro árvores, das quais retiraram-se discos visando a caracterização física, química e anatômica da madeira. Em relação a densidade básica (massa seca/volume verde), observaram-se os valores médio e ponderado de 0,421 g/cm-3 e 0,424 g/cm-3, respectivamente, o que a classifica como de baixa densidade. Na caracterização anatômica obtiveram-se os valores médios de comprimento de 3,14 mm, largura de 27,18 µm, diâmetro do lúmen de 15,39 µm e espessura da parede de 5,89 µm dos traqueídeos, que resultaram em 44,72%, 55,28%, 0,90 e 120,72 para os parâmetros de fração parede, coeficiente de flexibilidade, índice de Runkel e índice de enfeltramento, respectivamente. Para a composição química foram observados baixos teores de cinzas (0,25%) e extrativos (1,91%), e teores intermediários de lignina (29,93%) e holocelulose (67,91%). Desta forma a madeira de P. glabra apresenta potencial para produção de polpa celulósica, o qual deve ser comprovado por meio de ensaios de polpação.

Best practices for differentiated products demand estimation with PyBLP

AbstractDifferentiated products demand systems are a workhorse for understanding the price effects of mergers, the value of new goods, and the contribution of products to seller networks. Berry, Levinsohn, and Pakes (1995) provide a flexible random coefficients logit model which accounts for the endogeneity of prices. This article reviews and combines several recent advances related to the estimation of BLP‐type problems and implements an extensible generic interface via the PyBLP package. Monte Carlo experiments and replications suggest different conclusions than the prior literature: multiple local optima appear to be rare in well‐identified problems; good performance is possible even in small samples, particularly when “optimal instruments” are employed along with supply‐side restrictions.If Python is installed on your computer, PyBLP can be installed with the following command:pip install pyblp.Up‐to‐date documentation for the package is available athttps://pyblp.readthedocs.io.

Flexible derivative time-varying model in matched case-crossover studies for a small number of geographical locations among the participants.

In matched case-crossover studies, any stratum effect is removed by conditioning on the fixed number of case-control sets in the stratum, and hence, the conditional logistic regression model is not able to detect any effects associated with matching covariates. However, some matching covariates such as time and location often modify the effect of covariates, making the estimations obtained by conditional logistic regression incorrect. Therefore, in this paper, we propose a flexible derivative time-varying coefficient model to evaluate effect modification by time and location, in order to make correct statistical inference, when the number of locations is small. Our proposed model is developed under the Bayesian hierarchical model framework and allows us to simultaneously detect relationships between the predictor and binary outcome and between the predictor and time. Inference is proposed based on the derivative function of the estimated function to determine whether there is an effect modification due to time and/or location, for a small number of locations among the participants. We demonstrate the accuracy of the estimation using a simulation study and an epidemiological example of a 1-4 bidirectional case-crossover study of childhood aseptic meningitis with drinking water turbidity.

Biometry and verification of papermaking potential of secondary xylem fibers of two Theobroma species

Theobroma glandiflorum and T. cacao, known as cupuacu and cacao, respectively, are species widely used for food purposes. However, when plantations are renewed, these plants are discarded, making studies on the reuse of this material necessary. Thus, the objective of this study was to perform biometry of cellular elements and to investigate the papermaking potential of the fibers of these two species. We used the cellular element maceration technique to measure fiber and vessel element dimensions and calculated the fiber slenderness ratio, wall fraction, coefficient of flexibility and the Runkel index. According to the classification literature, the fibers of these species were of medium size, and there was a significant difference in wall thickness, with cupuacu fibers being thicker. The values of the fiber slenderness ratio and the coefficient of flexibility were higher in cocoa, while those of wall fraction and the Runkel index were higher in cupuacu. To conclude, the fibers of both species have papermaking potential. However, the paper manufactured with these fibers should be tested to confirm the results of this study.

Characterization of chia plant (Salvia hispanica) for pulping

In this paper, chia plant was characterized in terms of chemical, morphological, and anatomical properties. Chia plant was characterized with low α-cellulose (30.5%); moderate lignin (23.2%) with syringyl to guaiacyl ratio of 1.41; and shorter fiber length (0.67 mm) with thinner cell wall (1.91 μm) and good flexibility coefficient (71.44). Anatomical features showed that chia plant consists of vessels, fibers, parenchyma cells, and collenchyma cells. Chia plant pulping was evaluated in soda-anthraquinone (soda-AQ) and formic acid/peroxyformic acid (FA/PFA) processes. Chia plant was difficult to delignify in the alkaline process. The FA/PFA process produced higher pulp yield at the same kappa number than the soda-AQ process. Unbleached soda-AQ chia pulp exhibited good proper-ties in terms of tensile, bursting, and tearing strengths, even at the unrefined stage, due to high drainability of the pulps. Alkaline peroxide bleached FA/PFA pulp exhibited better papermaking properties and 2% higher brightness than the D0(EP)D1 bleached soda-AQ pulp.

Ferrite‐based room temperature negative temperature coefficient printed thermistors

Two screen printing inks were developed for the low-temperature fabrication of printed and flexible thick film negative temperature coefficient (NTC) thermistors able to operate at room temperature. The first of the two screen printing inks developed utilised cobalt ferrite (CoFe2O4) as the temperature sensing material with the second ink incorporating manganese ferrite (MnFe2O4). These were then screen printed onto lithographically printed silver interdigitated electrodes with a 200-micron track and gap using a synthetic paper (Teslin) as the substrate. The inks required a 10-minute curing step at 80oC. Preannealing of the ferrite powders before ink formulation enabled the avoidance of high-temperature processing post-fabrication typically required in industrial thermistor production. The printed thermistors were tested at a controlled constant humidity between 15 and 50oC. Both materials demonstrated typical natural logarithmic responses with high linearity and sensitivity.

Research of fastener distribution for typical irregular connections of civil aircraft

In this paper, based on the analytical method of calculating simple and regular single shear connector distribution, based on the engineering formula, the flexibility coefficient of different fasteners, pin spacing, plate width and plate thickness is given. The deformation coordination equation between adjacent fasteners is established. The diameter of different fasteners is given by the equilibrium conditions of the binding force. The calculation equations of fastener load distribution under the spacing of fastener, plate width and plate thickness have been calculated. The finite element model for calculating fastener load is established in finite element software based on finite element method. The calculation results of finite element method and analytical method are compared, and the analytical method is proved to be used to calculate plate width, plate thickness, fastener diameter, and the analysis method. The effectiveness of pin load distribution for typical connection structures with constant spacing between Fasteners is also presented.

Time-dependent response of laterally loaded piles and pile groups embedded in transversely isotropic saturated viscoelastic soils

This paper investigates the time-dependent response of laterally loaded single piles and pile groups embedded in transversely isotropic saturated viscoelastic soils. The solution for single piles subjected to lateral loads is solved by the coupling of the boundary element method and the Timoshenko beam theory. In the analysis of the pile group, the interaction between piles is taken into account and the generalized displacements caused by all piles are obtained by superimposing the influences of boundary forces on the soil-pile interfaces. The load distribution from the pile cap to pile tops is involved in the analysis. The presented method of laterally loaded piles and pile groups is verified through several examples, and the influences of some key parameters including transverse isotropy, the viscoelastic parameters, the flexibility coefficient, the slenderness ratio and the pile spacing are investigated by numerical examples.

Characterization and Pulping of Crops Residue: Eggplant, Cassava, Okra and Mulberry Plants

In this paper, four crops residues such as eggplant, cassava, okra and mulberry plants were assessed as papermaking raw materials. These crops residues had lower α-cellulose and holocellulose and moderate lignin content with syringyl:guaiacyl range of 1.05–1.63. The fiber length of eggplant, cassava, and mulberry plants were shorter (0.58–0.65 mm), while the same for okra plant was medium (1.14 mm). The Runkle ratios of these plant fibers were low (0.208–0.678), and flexibility coefficient was low to medium (55–79). All these non-wood plants were difficult to cook except eggplant plant. Eggplant plant produced screened pulp yield of 33.21 with kappa number of 22.9 at the conditions 3 h cooking at 170 °C with 20 alkali charge. Cassava plant showed the lowest screened pulp yield of 17.7% with kappa number 30.3 at the conditions 2 h cooking at 170 °C with 20 alkali charge. The okra plant pulp showed the best papermaking properties among these crops residues. Eggplant and okra plants can be used for brown packaging grade pulp.

Model-driven fault diagnosis of slant cracks in aero-hydraulic straight pipes

A model-driven fault diagnosis method for slant cracks in aero-hydraulic straight pipes is presented in this paper. First, fracture mechanics theory and the principle of strain energy release are used to derive an expression for the local flexibility coefficient of straight pipes with slant cracks. The inverse method of total flexibility is used to calculate the stiffness matrix of straight pipe elements with slant cracks. Second, the Euler-Bernoulli beam model theory is used in conjunction with the finite element method to construct a dynamic model of the cracked pipe. Finally, a contour map method is used to diagnose the slant crack fault and quantitatively determine the crack position and depth. Experimental results show that the proposed method can accurately and effectively identify a slant crack fault in aero-hydraulic pipelines.

Pinus halepensis and Eucalyptus camaldulensis grown in Egypt: A comparison between stem and branch properties for pulp and paper making

The utilization of branchwood as lignocellulosic raw material source for paper production may have the potential of solving the problem of the availability of raw material in the pulp and paper industry. This study therefore compared the chemical composition and fiber morphological indices (according to Franklin’s method) of stemwood and branchwood in Eucalyptus camaldulensis and Pinus halepensis trees grown in Egypt. The statistical analysis showed a significant effect of species, wood type (stem and branchwood), and their interaction on the measured chemical constituents and fiber morphological indices at 0.05 significance level. In both genera, the stemwood exhibited a higher percentage of cellulose and hemicellulose and was lower in lignin, total extractives, and ash than those measured in branchwood. Also in both genera, the stemwood was higher in fiber length, Runkel ratio, rigidity coefficient, Muhlsteph ratio, and Luce’s shape factor, and lower in basic density and flexibility coefficient than those in branchwood. Based on the chemical analysis and the fiber morphological indices, the stemwood and branchwood of both species were suitable for paper production with various qualities. Moreover, good correlations were found in both stem and branchwood between the basic density and the fiber wall thickness and fiber lumen diameter. ln contrast, there was an independent association between the stemwood basic density and the fiber length, and this relationship in branchwood was positive for both genera.

Reactive Power Support Adequacy at the DSO/TSO Interface

The exchange of reactive power at the interface between distribution and transmission systems gains significant importance with ongoing relocation of generators to lower voltage levels. To keep transmission systems operation secure and stable, distribution systems may need to be more flexible when exchanging power at the interface with the overlaying grid. A flexibility measure of this interface is proposed by this paper through introduction of flexibility coefficients. These coefficients are calculated by comparing DSO capability and TSO desirability surfaces. These surfaces describe the distribution system’s capability to provide flexible reactive power exchange and the transmission system’s needs to use these flexibilities. Since the surfaces can be calculated independently, the newly proposed method of flexibility assessment can be applied without substantial exchange of system information between DSO and TSO. The proposed concept is illustrated on the Nordic 32 system for a case of the connection of two differently behaving distribution systems.