WorldWideScience

Sample records for biomass constituting equations

  1. Constitutive equations for two-phase flows

    International Nuclear Information System (INIS)

    Boure, J.A.

    1974-12-01

    The mathematical model of a system of fluids consists of several kinds of equations complemented by boundary and initial conditions. The first kind equations result from the application to the system, of the fundamental conservation laws (mass, momentum, energy). The second kind equations characterize the fluid itself, i.e. its intrinsic properties and in particular its mechanical and thermodynamical behavior. They are the mathematical model of the particular fluid under consideration, the laws they expressed are so called the constitutive equations of the fluid. In practice the constitutive equations cannot be fully stated without reference to the conservation laws. Two classes of model have been distinguished: mixture model and two-fluid models. In mixture models, the mixture is considered as a single fluid. Besides the usual friction factor and heat transfer correlations, a single constitutive law is necessary. In diffusion models, the mixture equation of state is replaced by the phasic equations of state and by three consitutive laws, for phase change mass transfer, drift velocity and thermal non-equilibrium respectively. In the two-fluid models, the two phases are considered separately; two phasic equations of state, two friction factor correlations, two heat transfer correlations and four constitutive laws are included [fr

  2. Mathematical modeling and the two-phase constitutive equations

    International Nuclear Information System (INIS)

    Boure, J.A.

    1975-01-01

    The problems raised by the mathematical modeling of two-phase flows are summarized. The models include several kinds of equations, which cannot be discussed independently, such as the balance equations and the constitutive equations. A review of the various two-phase one-dimensional models proposed to date, and of the constitutive equations they imply, is made. These models are either mixture models or two-fluid models. Due to their potentialities, the two-fluid models are discussed in more detail. To avoid contradictions, the form of the constitutive equations involved in two-fluid models must be sufficiently general. A special form of the two-fluid models, which has particular advantages, is proposed. It involves three mixture balance equations, three balance equations for slip and thermal non-equilibriums, and the necessary constitutive equations [fr

  3. Constitutive equations for discrete electromagnetic problems over polyhedral grids

    International Nuclear Information System (INIS)

    Codecasa, Lorenzo; Trevisan, Francesco

    2007-01-01

    In this paper a novel approach is proposed for constructing discrete counterparts of constitutive equations over polyhedral grids which ensure both consistency and stability of the algebraic equations discretizing an electromagnetic field problem. The idea is to construct discrete constitutive equations preserving the thermodynamic relations for constitutive equations. In this way, consistency and stability of the discrete equations are ensured. At the base, a purely geometric condition between the primal and the dual grids has to be satisfied for a given primal polyhedral grid, by properly choosing the dual grid. Numerical experiments demonstrate that the proposed discrete constitutive equations lead to accurate approximations of the electromagnetic field

  4. Constitutive equations for Zr1Nb. II

    International Nuclear Information System (INIS)

    Novak, J.

    1986-01-01

    Based on existing knowledge and constitutive equations for non-irradiated material, constitutive equations were written for Zr1Nb irradiated at 573 K at deformation in the direction of forming. Constitutive equations express the following material characteristics: dependence of shear strength on fast neutron fluence, superposition of deformation hardening and subsequent radiation hardening, the effect of stress on deformation rate, and for fluences above ca. 10 24 n.m -2 (E>1 MeV) the course of the deformation curve for various fluence levels. The values apply for temperatures and rates of deformation which are characteristic of transient processes during changes in the power output of fuel elements of pressurized water reactors. (J.B.)

  5. Constitutive Equation with Varying Parameters for Superplastic Flow Behavior

    Science.gov (United States)

    Guan, Zhiping; Ren, Mingwen; Jia, Hongjie; Zhao, Po; Ma, Pinkui

    2014-03-01

    In this study, constitutive equations for superplastic materials with an extra large elongation were investigated through mechanical analysis. From the view of phenomenology, firstly, some traditional empirical constitutive relations were standardized by restricting some strain paths and parameter conditions, and the coefficients in these relations were strictly given new mechanical definitions. Subsequently, a new, general constitutive equation with varying parameters was theoretically deduced based on the general mechanical equation of state. The superplastic tension test data of Zn-5%Al alloy at 340 °C under strain rates, velocities, and loads were employed for building a new constitutive equation and examining its validity. Analysis results indicated that the constitutive equation with varying parameters could characterize superplastic flow behavior in practical superplastic forming with high prediction accuracy and without any restriction of strain path or deformation condition, showing good industrial or scientific interest. On the contrary, those empirical equations have low prediction capabilities due to constant parameters and poor applicability because of the limit of special strain path or parameter conditions based on strict phenomenology.

  6. FIA's volume-to-biomass conversion method (CRM) generally underestimates biomass in comparison to published equations

    Science.gov (United States)

    David. C. Chojnacky

    2012-01-01

    An update of the Jenkins et al. (2003) biomass estimation equations for North American tree species resulted in 35 generalized equations developed from published equations. These 35 equations, which predict aboveground biomass of individual species grouped according to a taxa classification (based on genus or family and sometimes specific gravity), generally predicted...

  7. Above-ground biomass equations for Pinus radiata D. Don in Asturias

    Directory of Open Access Journals (Sweden)

    E. Canga

    2013-12-01

    Full Text Available Aim of the study: The aim of this study was to develop a model for above-ground biomass estimation for Pinus radiata D. Don in Asturias.Area of study: Asturias (NE of Spain.Material and methods: Different models were fitted for the different above-ground components and weighted regression was used to correct heteroscedasticity. Finally, all the models were refitted simultaneously by use of Nonlinear Seemingly Unrelated Regressions (NSUR to ensure the additivity of biomass equations.Research highlights: A system of four biomass equations (wood, bark, crown and total biomass was develop, such that the sum of the estimations of the three biomass components is equal to the estimate of total biomass. Total and stem biomass equations explained more than 92% of observed variability, while crown and bark biomass equations explained 77% and 89% respectively.Keywords: radiata pine; plantations; biomass.

  8. A review of forest and tree plantation biomass equations in Indonesia

    NARCIS (Netherlands)

    Anitha, Kamalakumari; Verchot, Louis V.; Joseph, Shijo; Herold, Martin; Manuri, Solichin; Avitabile, Valerio

    2015-01-01

    Key message: We compiled 2,458 biomass equations from 168 destructive sampling studies in Indonesia. Unpublished academic theses contributed the largest share of the biomass equations. The availability of the biomass equations was skewed to certain regions, forest types, and species. Further

  9. Study on the creep constitutive equation of Hastelloy X, (1)

    International Nuclear Information System (INIS)

    Hada, Kazuhiko; Mutoh, Yasushi

    1983-01-01

    A creep constitutive equation of Hastelloy X was obtained from available experimental data. A sensitivity analysis of this creep constitutive equation was carried out. As the result, the following were revealed: (i) Variations in creep behavior with creep constitutive equation are not small. (ii) In a simpler stress change pattern, variations in creep behavior are similar to those in the corresponding fundamental creep characteristics (creep strain curve, stress relaxation curve, etc.). (iii) Cumulative creep damage estimated in accordance with ASME Boiler and Pressure Vessel Code Case N-47 from a stress history predicted by ''the standard creep constitutive equation'' which predicts the average behavior of creep strain curve data is not thought to be on the safe side on account of uncertainties in creep damage caused by variations in creep strain curve. (author)

  10. Improving North American forest biomass estimates from literature synthesis and meta-analysis of existing biomass equations

    Science.gov (United States)

    David C. Chojnacky; Jennifer C. Jenkins; Amanda K. Holland

    2009-01-01

    Thousands of published equations purport to estimate biomass of individual trees. These equations are often based on very small samples, however, and can provide widely different estimates for trees of the same species. We addressed this issue in a previous study by devising 10 new equations that estimated total aboveground biomass for all species in North America (...

  11. A stable computational scheme for stiff time-dependent constitutive equations

    International Nuclear Information System (INIS)

    Shih, C.F.; Delorenzi, H.G.; Miller, A.K.

    1977-01-01

    Viscoplasticity and creep type constitutive equations are increasingly being employed in finite element codes for evaluating the deformation of high temperature structural members. These constitutive equations frequently exhibit stiff regimes which makes an analytical assessment of the structure very costly. A computational scheme for handling deformation in stiff regimes is proposed in this paper. By the finite element discretization, the governing partial differential equations in the spatial (x) and time (t) variables are reduced to a system of nonlinear ordinary differential equations in the independent variable t. The constitutive equations are expanded in a Taylor's series about selected values of t. The resulting system of differential equations are then integrated by an implicit scheme which employs a predictor technique to initiate the Newton-Raphson procedure. To examine the stability and accuracy of the computational scheme, a series of calculations were carried out for uniaxial specimens and thick wall tubes subjected to mechanical and thermal loading. (Auth.)

  12. Structure and Calibration of Constitutive Equations for Granular Soils

    Directory of Open Access Journals (Sweden)

    Sawicki Andrzej

    2015-02-01

    Full Text Available The form of incremental constitutive equations for granular soils is discussed for the triaxial configuration. The classical elasto-plastic approach and the semi-empirical model are discussed on the basis of constitutive relations determined directly from experimental data. First, the general structure of elasto-plastic constitutive equations is presented. Then, the structure of semiempirical constitutive equations is described, and a method of calibrating the model is presented. This calibration method is based on a single experiment, performed in the triaxial apparatus, which also involves a partial verification of the model, on an atypical stress path. The model is shown to give reasonable predictions. An important feature of the semi-empirical incremental model is the definition of loading and unloading, which is different from that assumed in elasto-plasticity. This definition distinguishes between spherical and deviatoric loading/unloading. The definition of deviatoric loading/unloading has been subject to some criticism. It was therefore discussed and clarified in this paper on the basis of the experiment presented.

  13. Study on the creep constitutive equation of Hastelloy X, (1)

    International Nuclear Information System (INIS)

    Suzuki, Kazuhiko; Mutoh, Yasushi

    1983-01-01

    In order to carry out the structural design of high temperature pipings, intermediate heat exchangers and isolating valves for a multipurpose high temperature gas-cooled reactor, in which coolant temperature reaches 1000 deg C, the creep characteristics of Hastelloy X used as the heat resistant material must be clarified. In addition to usual creep rupture life and the time to reach a specified creep strain, the dependence of creep strain curves on time, temperature and stress must be determined and expressed with equations. Therefore, using the creep data of Hastelloy X given in the literatures, the creep constitutive equation was made. Since the creep strain curves under the same test condition were different according to heats, the sensitivity analysis of the creep constitutive equation was performed. The form of the creep constitutive equation was determined to be Garofalo type. The result of the sensitivity analysis is reported. (Kako, I.)

  14. Development of constitutive equations for nuclear reactor core materials

    International Nuclear Information System (INIS)

    Lee, D.; Zaverl, F. Jr.; Plaza-Meyer, E.

    1980-01-01

    A set of strain rate dependent constitutive equations has been described which is capable of predicting deformation behavior of anisotropic metals under complex loading conditions with or without the presence of a neutron flux. The important feature of the constitutive equations is that they describe history dependent plastic deformation behavior of anisotropic metals under three-dimensional stress states. Since the analytical model accounts for the effect of prior deformation history at all times, it is capable of handling consecutive or simultaneous loading histories, such as post-irradiation loading, in-pile loading, etc. It is demonstrated that the general form of the constitutive relations is consistent with experimental observations made for Zircaloys under both unirradiated and irradiated conditions. (orig.)

  15. Extended irreversible thermodynamics and the Jeffreys type constitutive equations

    International Nuclear Information System (INIS)

    Serdyukov, S.I.

    2003-01-01

    A postulate of extended irreversible thermodynamics is considered, according to which the entropy density is a function of the internal energy, the specific volume, and their material time derivatives. On the basis of this postulate, entropy balance equations and phenomenological equations are obtained, which directly lead to the Jeffreys type constitutive equations

  16. Application of viscoplastic constitutive equations in finite element programs

    International Nuclear Information System (INIS)

    Hornberger, K.; Stamm, H.

    1987-04-01

    The general mathematical formulation of frequently used viscoplastic constitutive equations is explained and Robinson's model is discussed in more detail. The implementation of viscoplastic constitutive equations into Finite Element programs (such as ABAQUS) is described using Robinson's model as an example. For the numerical integration both an explicit (explicit Euler) and an implicit (generalized midpoint rule) integration scheme is utilized in combination with a time step control strategy. In the implicit integration scheme, convergence in solving a system of nonlinear algebraic equation is improved introducing a projection method. The efficiency of the implemented procedures is demonstrated for different homogeneous load cases as well as for creep loading and strain controlled cyclic loading of a perforated plate. (orig./HP) [de

  17. A New Theory of Non-Linear Thermo-Elastic Constitutive Equation of Isotropic Hyperelastic Materials

    Science.gov (United States)

    Li, Chen; Liao, Yufei

    2018-03-01

    Considering the influence of temperature and strain variables on materials. According to the relationship of conjugate stress-strain, a complete and irreducible non-linear constitutive equation of isotropic hyperelastic materials is derived and the constitutive equations of 16 types of isotropic hyperelastic materials are given we study the transformation methods and routes of 16 kinds of constitutive equations and the study proves that transformation of two forms of constitutive equation. As an example of application, the non-linear thermo-elastic constitutive equation of isotropic hyperelastic materials is combined with the natural vulcanized rubber experimental data in the existing literature base on MATLAB, The results show that the fitting accuracy is satisfactory.

  18. Lignocellulose Biomass: Constitutive Polymers. Biological Processes of Lignin Degradation

    International Nuclear Information System (INIS)

    Martin, C.; Manzanares, P.

    1994-01-01

    The structure of the lignocellulosic materials and the chemical composition of their main constitutive polymers, cellulose, hemicelluloses and lignin are described. The most promising transformation processes according to the type of biomass considered: hardwood, softwood an herbaceous and the perspectives of biotechnological processes for bio pulping, bio bleaching and effluents decolorisation in the paper pulp industry are also discussed. (Author) 7 refs

  19. Materials with memory initial-boundary value problems for constitutive equations with internal variables

    CERN Document Server

    Alber, Hans-Dieter

    1998-01-01

    This book contributes to the mathematical theory of systems of differential equations consisting of the partial differential equations resulting from conservation of mass and momentum, and of constitutive equations with internal variables. The investigations are guided by the objective of proving existence and uniqueness, and are based on the idea of transforming the internal variables and the constitutive equations. A larger number of constitutive equations from the engineering sciences are presented. The book is therefore suitable not only for specialists, but also for mathematicians seeking for an introduction in the field, and for engineers with a sound mathematical background.

  20. Efficacy of generic allometric equations for estimating biomass: a test in Japanese natural forests.

    Science.gov (United States)

    Ishihara, Masae I; Utsugi, Hajime; Tanouchi, Hiroyuki; Aiba, Masahiro; Kurokawa, Hiroko; Onoda, Yusuke; Nagano, Masahiro; Umehara, Toru; Ando, Makoto; Miyata, Rie; Hiura, Tsutom

    2015-07-01

    Accurate estimation of tree and forest biomass is key to evaluating forest ecosystem functions and the global carbon cycle. Allometric equations that estimate tree biomass from a set of predictors, such as stem diameter and tree height, are commonly used. Most allometric equations are site specific, usually developed from a small number of trees harvested in a small area, and are either species specific or ignore interspecific differences in allometry. Due to lack of site-specific allometries, local equations are often applied to sites for which they were not originally developed (foreign sites), sometimes leading to large errors in biomass estimates. In this study, we developed generic allometric equations for aboveground biomass and component (stem, branch, leaf, and root) biomass using large, compiled data sets of 1203 harvested trees belonging to 102 species (60 deciduous angiosperm, 32 evergreen angiosperm, and 10 evergreen gymnosperm species) from 70 boreal, temperate, and subtropical natural forests in Japan. The best generic equations provided better biomass estimates than did local equations that were applied to foreign sites. The best generic equations included explanatory variables that represent interspecific differences in allometry in addition to stem diameter, reducing error by 4-12% compared to the generic equations that did not include the interspecific difference. Different explanatory variables were selected for different components. For aboveground and stem biomass, the best generic equations had species-specific wood specific gravity as an explanatory variable. For branch, leaf, and root biomass, the best equations had functional types (deciduous angiosperm, evergreen angiosperm, and evergreen gymnosperm) instead of functional traits (wood specific gravity or leaf mass per area), suggesting importance of other traits in addition to these traits, such as canopy and root architecture. Inclusion of tree height in addition to stem diameter improved

  1. Elastic-Plastic Constitutive Equation of WC-Co Cemented Carbides with Anisotropic Damage

    International Nuclear Information System (INIS)

    Hayakawa, Kunio; Nakamura, Tamotsu; Tanaka, Shigekazu

    2007-01-01

    Elastic-plastic constitutive equation of WC-Co cemented carbides with anisotropic damage is proposed to predict a precise service life of cold forging tools. A 2nd rank symmetric tensor damage tensor is introduced in order to express the stress unilaterality; a salient difference in uniaxial behavior between tension and compression. The conventional framework of irreversible thermodynamics is used to derive the constitutive equation. The Gibbs potential is formulated as a function of stress, damage tensor, isotropic hardening variable and kinematic hardening variable. The elastic-damage constitutive equation, conjugate forces of damage, isotropic hardening and kinematic hardening variable is derived from the potential. For the kinematic hardening variable, the superposition of three kinematic hardening laws is employed in order to improve the cyclic behavior of the material. For the evolution equation of the damage tensor, the damage is assumed to progress by fracture of the Co matrix - WC particle interface and by the mechanism of fatigue, i.e. the accumulation of microscopic plastic strain in matrix and particles. By using the constitutive equations, calculation of uniaxial tensile and compressive test is performed and the results are compared with the experimental ones in the literature. Furthermore, finite element analysis on cold forward extrusion was carried out, in which the proposed constitutive equation was employed as die insert material

  2. Predicting of biomass in Brazilian tropical dry forest: a statistical evaluation of generic equations

    Directory of Open Access Journals (Sweden)

    ROBSON B. DE LIMA

    2017-08-01

    Full Text Available ABSTRACT Dry tropical forests are a key component in the global carbon cycle and their biomass estimates depend almost exclusively of fitted equations for multi-species or individual species data. Therefore, a systematic evaluation of statistical models through validation of estimates of aboveground biomass stocks is justifiable. In this study was analyzed the capacity of generic and specific equations obtained from different locations in Mexico and Brazil, to estimate aboveground biomass at multi-species levels and for four different species. Generic equations developed in Mexico and Brazil performed better in estimating tree biomass for multi-species data. For Poincianella bracteosa and Mimosa ophthalmocentra, only the Sampaio and Silva (2005 generic equation was the most recommended. These equations indicate lower tendency and lower bias, and biomass estimates for these equations are similar. For the species Mimosa tenuiflora, Aspidosperma pyrifolium and for the genus Croton the specific regional equations are more recommended, although the generic equation of Sampaio and Silva (2005 is not discarded for biomass estimates. Models considering gender, families, successional groups, climatic variables and wood specific gravity should be adjusted, tested and the resulting equations should be validated at both local and regional levels as well as on the scales of tropics with dry forest dominance.

  3. Predicting of biomass in Brazilian tropical dry forest: a statistical evaluation of generic equations.

    Science.gov (United States)

    Lima, Robson B DE; Alves, Francisco T; Oliveira, Cinthia P DE; Silva, José A A DA; Ferreira, Rinaldo L C

    2017-01-01

    Dry tropical forests are a key component in the global carbon cycle and their biomass estimates depend almost exclusively of fitted equations for multi-species or individual species data. Therefore, a systematic evaluation of statistical models through validation of estimates of aboveground biomass stocks is justifiable. In this study was analyzed the capacity of generic and specific equations obtained from different locations in Mexico and Brazil, to estimate aboveground biomass at multi-species levels and for four different species. Generic equations developed in Mexico and Brazil performed better in estimating tree biomass for multi-species data. For Poincianella bracteosa and Mimosa ophthalmocentra, only the Sampaio and Silva (2005) generic equation was the most recommended. These equations indicate lower tendency and lower bias, and biomass estimates for these equations are similar. For the species Mimosa tenuiflora, Aspidosperma pyrifolium and for the genus Croton the specific regional equations are more recommended, although the generic equation of Sampaio and Silva (2005) is not discarded for biomass estimates. Models considering gender, families, successional groups, climatic variables and wood specific gravity should be adjusted, tested and the resulting equations should be validated at both local and regional levels as well as on the scales of tropics with dry forest dominance.

  4. ALLOMETRIC EQUATIONS FOR ESTIMATING ABOVEGROUND BIOMASS IN PAPUA TROPICAL FOREST

    Directory of Open Access Journals (Sweden)

    Sandhi Imam Maulana

    2014-10-01

    Full Text Available Allometric equations can be used to estimate biomass and carbon stock of  the forest. However, so far the allometric equations for commercial species in Papua tropical forests have not been appropriately developed. In this research, allometric equations are presented based on the genera of  commercial species. Few equations have been developed for the commercial species of  Intsia, Pometia, Palaquium and Vatica genera and an equation of  a mix of  these genera. The number of  trees sampled in this research was 49, with diameters (1.30 m above-ground or above buttresses ranging from 5 to 40 cm. Destructive sampling was used to collect the samples where Diameter at Breast Height (DBH and Wood Density (WD were used as predictors for dry weight of  Total Above-Ground Biomass (TAGB. Model comparison and selection were based on the values of  F-statistics, R-sq, R-sq (adj, and average deviation. Based on these statistical indicators, the most suitable model for Intsia, Pometia, Palaquium and Vatica genera respectively are Log(TAGB = -0.76 + 2.51Log(DBH, Log(TAGB = -0.84 + 2.57Log(DBH, Log(TAGB = -1.52 + 2.96Log(DBH, and Log(TAGB = -0.09 + 2.08Log(DBH. Additional explanatory variables such as Commercial Bole Height (CBH do not really increase the indicators’ goodness of  fit for the equation. An alternative model to incorporate wood density should  be considered for estimating the above-ground biomass for mixed genera. Comparing the presented mixed-genera equation; Log(TAGB = 0.205 + 2.08Log(DBH + 1.75Log(WD, R-sq: 97.0%, R-sq (adj: 96.9%, F statistics 750.67, average deviation: 3.5%; to previously published datashows that this local species specific equation differs substantially from previously published equations and this site-specific equation is  considered to give a better estimation of  biomass.

  5. Implementation of thermo-viscoplastic constitutive equations into the finite element code ABAQUS

    International Nuclear Information System (INIS)

    Youn, Sam Son; Lee, Soon Bok; Kim, Jong Bum; Lee, Hyeong Yeon; Yoo, Bong

    1998-01-01

    Sophisticated viscoplatic constitutive laws describing material behavior at high temperature have been implemented in the general-purpose finite element code ABAQUS to predict the viscoplastic response of structures to cyclic loading. Because of the complexity of viscoplastic constitutive equation, the general implementation methods are developed. The solution of the non-linear system of algebraic equations arising from time discretization is determined using line-search and back-tracking in combination with Newton method. The time integration method of the constitutive equations is based on semi-implicit method with efficient time step control. For numerical examples, the viscoplastic model proposed by Chaboche is implemented and several applications are illustrated

  6. A strategy of implementation of the improved constitutive equations for the advanced subchannel code

    International Nuclear Information System (INIS)

    Shirai, Hiroshi; Hotta, Akitoshi; Ninokata, Hisashi

    2004-01-01

    To develop the advanced subchannel analysis code, the dominant factors that influence the boiling transitional process must be taken into account in the mechanistic constitutive equations based on the flow geometries and the fluid properties. The dominant factors that influence the boiling transitional processes are (1) the gas-liquid re-distribution by cross flow, (2) the liquid film dryout, (3) the two-phase flow regime transition, (4) the droplet deposition, and (5) the spacer-droplet interaction. At first, we indicated the strategy for the development of the constitutive equations for the five dominant factors based on the experimental database by the latest measurement technique and the latest computational fluid dynamics method. Then, the problems of the present constitutive equations and the improvement plan of the constitutive equations were indicated. Finally, the layered structure for the two-phase/three-field subchannel code including the new constitutive equations was designed. (author)

  7. Allometric equations for estimating standing biomass of Avicennia marina in Bushehr of Iran

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    Akbar Ghasemi

    2016-07-01

    Full Text Available Today, it is important to use of ecological indicators, such as biomass for recognizing the special status of ecosystems, such as mangrove forests and also monitoring and evaluating changes through a specific period. Because using the direct method of evaluating biomass would be destructive, it is common in all similar area to use determine exact Allometric equations by using the statistical relationship between the structural characteristics of trees and their biomass and use these equations to estimate the biomass of trees. The aim of this study is estimate the aboveground biomass of mangroves and determine Allometric models for Nayband area in Bushehr, located in southern Iran. A number of mangrove trees were randomly selected. Collar diameter, crown diameter and tree height of standing trees were measured. After logging and weighing fresh weight, dry weight, trunk and branches were obtained in laboratory and biomass of components was calculated. The relationship between quantities feature of trees and biomass for determination of allometric equation was studied by using linear, power and exponential regression. The equations were compared with each other based on the different modeling parameters. The highest significant correlation was found between crown diameters and dry weight (R > 0.90. The best equations were obtained by means of an exponential and power regression models (R2adj> 0.90. The models were obtained from explained factor, suggests that there might be a relationship between the characteristics of mangrove trees and biomass.

  8. MINI-TRAC code: a driver program for assessment of constitutive equations of two-fluid model

    International Nuclear Information System (INIS)

    Akimoto, Hajime; Abe, Yutaka; Ohnuki, Akira; Murao, Yoshio

    1991-05-01

    MINI-TRAC code, a driver program for assessment of constitutive equations of two-fluid model, has been developed to perform assessment and improvement of constitutive equations of two-fluid model widely and efficiently. The MINI-TRAC code uses one-dimensional conservation equations for mass, momentum and energy based on the two-fluid model. The code can work on a personal computer because it can be operated with a core memory size less than 640 KB. The MINI-TRAC code includes constitutive equations of TRAC-PF1/MOD1 code, TRAC-BF1 code and RELAP5/MOD2 code. The code is modulated so that one can easily change constitutive equations to perform a test calculation. This report is a manual of the MINI-TRAC code. The basic equations, numerics, constitutive, equations included in the MINI-TRAC code will be described. The user's manual such as input description will be presented. The program structure and contents of main variables will also be mentioned in this report. (author)

  9. A constitutive equation for creep fracture under constant, variable or cyclic positive stress

    International Nuclear Information System (INIS)

    Snedden, J.D.

    1977-01-01

    Prediction of creep fracture of metals under variable stress is one of the most difficult problems of applied mechanics. At NEL this problem is under investigation using an approach in which creep is represented by two macroscopic components: an anelastic (reversible) component and a plastic (irreversible) component. Under variable loading conditions, the anelastic component's behaviour will be most important and, if an experimental programme is logically planned, the structural processes responsible will be implicit in the resulting constitutive equation describing the material's behaviour. The present paper deals with the development and application of a constitutive equation for creep fracture of RR58 Aluminium alloy at 180 0 C under variable stress and such a constitutive equation can be extrapolated to cover long-time behaviour just as with conventional constant stress creep fracture equations. Constant stress, in fact, is one of the boundary conditions of the general constitutive equation, representing zero prior damage. The other boundary condition is that of 'cadence loading' in which the stress is completely removed and then re-applied in a cyclic fashion. (Auth.)

  10. Mechanical modeling for magnetorheological elastomer isolators based on constitutive equations and electromagnetic analysis

    Science.gov (United States)

    Wang, Qi; Dong, Xufeng; Li, Luyu; Ou, Jinping

    2018-06-01

    As constitutive models are too complicated and existing mechanical models lack universality, these models are beyond satisfaction for magnetorheological elastomer (MRE) devices. In this article, a novel universal method is proposed to build concise mechanical models. Constitutive model and electromagnetic analysis were applied in this method to ensure universality, while a series of derivations and simplifications were carried out to obtain a concise formulation. To illustrate the proposed modeling method, a conical MRE isolator was introduced. Its basic mechanical equations were built based on equilibrium, deformation compatibility, constitutive equations and electromagnetic analysis. An iteration model and a highly efficient differential equation editor based model were then derived to solve the basic mechanical equations. The final simplified mechanical equations were obtained by re-fitting the simulations with a novel optimal algorithm. In the end, verification test of the isolator has proved the accuracy of the derived mechanical model and the modeling method.

  11. Constitutive equations for describing high-temperature inelastic behavior of structural alloys

    International Nuclear Information System (INIS)

    Robinson, D.N.; Pugh, C.E.; Corum, J.M.

    1976-01-01

    This paper addresses constitutive equations for the description of inelastic behavior of LMFBR structural alloys at elevated temperatures. Both elastic-plastic (time-independent) and creep (time-dependent) deformations are considered for types 304 and 316 stainless steel and 2 1 / 4 Cr--1 Mo steel. The constitutive equations identified for interim use in design analyses are described along with the assumptions and data on which they are based. Areas where improvements are needed are identified, and some alternate theories that are being pursued are outlined

  12. Constitutional equations of thermal stresses of particle-reinforced composite

    International Nuclear Information System (INIS)

    Asakawa, Atsushi; Noda, Naotake; Tohgo, Keiichiro; Tsuji, Tomoaki.

    1994-01-01

    Functionally gradient materials (FGM) have been developed as ultrahigh-heat-resistant materials in aircraft, space engineering and nuclear fields. In the heat-resistant FGM which contain particles (ceramics) in the matrix (metal), the matrix will be subjected to plastic deformation, particles will be debonded, and finally cracks will be generated. The constitutive equations of FGM which take into account the damage process and change in temperature are necessary in order to solve these phenomena. In this paper, the constitutive equations of particle-reinforced composites with consideration of the damage process and change in temperature are estimated by the equivalent inclusion method in terms of elastoplasticity. The stress-strain relations and the coefficients of linear thermal expansion of the composites (Al-PSZ and Ti-PSZ) are calculated in ultrahigh temperature. (author)

  13. Validation of constitutive equations for steel

    International Nuclear Information System (INIS)

    Valentin, T.; Magain, P.; Quik, M.; Labibes, K.; Albertini, C.

    1997-01-01

    High strain rate mechanical properties are a major concern for each steel manufacturer, especially with respect to thin sheet steel used in the automotive branch. We began to study this topic by starting a project with the following goals: acquiring reliable experimental data, understanding in depth the energy absorption in thin sheet steel and finding the right constitutive material equation. The first part of the project has been presented in. In this paper we present data computation and comparison with the existing material model theories to exploit the experimental data. (orig.)

  14. Nonlocal constitutive equations of elasto-visco-plasticity coupled with damage and temperature

    Directory of Open Access Journals (Sweden)

    Liu Weijie

    2016-01-01

    Full Text Available In this paper, the nonlocal anisothermal elasto-visco-plastic constitutive equations strongly coupled with ductile isotropic damage, nonlinear isotropic hardening and kinematic hardening are developed to model the material behaviour under finite strain. The new micromorphic variable of damage is introduced into the principle of virtual power and new additional balance equations are obtained. Thermodynamically-consistent nonlocal constitutive equations are then deduced. The evolution equations are deduced from the generalized normality rule for the Norton-Hoff visco-plastic potential. This model is used to simulate various material responses under different velocities at high temperature. The micromorphic parameters of damage: micromorphic density and H moduli are studied to examine the effects of micromorphic damage. Biaxial tension is performed to make a comparison between the local damage model and the micromorphic damage model.

  15. Evaluation of high temperature mechanical properties and constitutive equation of austenitic stainless steels

    International Nuclear Information System (INIS)

    Blanchard, P.; Tortel, J.

    1985-08-01

    A large amount of experimental data (tensile tests, creep tests, cyclic strain tests, relaxation experiments and biaxial experiments) on 17-12 Mo SPH (316 L SPH) stainless steel used for building the primary loop of Super Phenix Reactor have been obtained during the last years. The aim of this paper is to illustrate by a few examples the work done in the constitutive equations area using this powerful data base. Numerous semiempirical equations have been developed to represent tensile, cyclic, creep or relaxation tests on 17-12 Mo SPH (316 L SPH) stainless steel. These equations, althrough not being able to be properly called ''constitutive equations'' in the full sense of the word, are nevertheless very useful for design studies. Actually these semiempirical equations are necessary tools for building elastic analysis's rules. Some examples of these equations are given along with specific applications (creep-fatigue rules). The qualitative and semiquantitative comparisons of the stress-strain behaviour (both uniaxial and biaxial) predicted by the most common constitutive equations (PRAGER, MEIJERS, HART, CHABOCHE, KRIEB, MILLER, ROBINSON) with the actual behaviour of 17-12 Mo SPH (316 L SPH) steel, allows us to shed some light on the strengths and weaknesses of these equations. This comparison is presented and discussed. The way to more realistic equations is shown. A detailed and quantitative comparison of the capabilities of two models, the CHABOCHE model and the multilayer unified model which has been developed is presented

  16. On establishing constitutive equations for use in design of high-temperature fast-reactor structures

    International Nuclear Information System (INIS)

    Pugh, C.E.

    1978-01-01

    The presentation describes the approach being used to establish constitutive equations for wide use in the design of fast breeder reactor (FBR) components in the US. The approach combines exploratory experiments, constitutive model studies, studies of computational techniques, and tests of simple structural configurations. Short-time (elastic-plastic) behavior, long-time (creep) behavior, and their interactions are considered, and some of the background to equations now identified for use in current FBR design applications involving three structural alloys is discussed. Comments are also given on current efforts aimed at identifying improved constitutive equations for these alloys and on properties data required for design applications. References are cited which have addressed the status of the process at various times. (Auth.)

  17. Development and validation of constitutive equation of HBS irradiation swelling considering hydrostatic pressure

    International Nuclear Information System (INIS)

    Gao Lijun; Jiang Shengyao; Yu Jiyang; Chen Bingde; Xiao Zhong

    2014-01-01

    The mechanism of hydrostatic pressure affecting the irradiation swelling of UO_2 high burnup structure was analyzed. Three basic assumptions used to develop the constitutive equation of irradiation swelling were made accordingly. It is concluded that hydrostatic pressure imposes an important impact on irradiation swelling mainly through compressing the UO_2 high burnup structure pores. Based on the already developed correlation of the irradiation swelling of UO_2 high burnup structure, pore shrinkage due to the application of hydrostatic pressure and thus the reduction of irradiation swelling of UO_2 high burnup structure were determined quantitatively, and the constitutive equation of irradiation swelling of UO_2 high burnup structure considering the hydrostatic pressure was constructed successfully. The constitutive equation is validated using available irradiation swelling data of UO_2 high burnup structure, which demonstrates its reasonability. (authors)

  18. Direct test of a nonlinear constitutive equation for simple turbulent shear flows using DNS data

    Science.gov (United States)

    Schmitt, François G.

    2007-10-01

    Several nonlinear constitutive equations have been proposed to overcome the limitations of the linear eddy-viscosity models to describe complex turbulent flows. These nonlinear equations have often been compared to experimental data through the outputs of numerical models. Here we perform a priori analysis of nonlinear eddy-viscosity models using direct numerical simulation (DNS) of simple shear flows. In this paper, the constitutive equation is directly checked using a tensor projection which involves several invariants of the flow. This provides a 3 terms development which is exact for 2D flows, and a best approximation for 3D flows. We provide the quadratic nonlinear constitutive equation for the near-wall region of simple shear flows using DNS data, and estimate their coefficients. We show that these coefficients have several common properties for the different simple shear flow databases considered. We also show that in the central region of pipe flows, where the shear rate is very small, the coefficients of the constitutive equation diverge, indicating the failure of this representation for vanishing shears.

  19. Evaluating revised biomass equations: are some forest types more equivalent than others?

    Science.gov (United States)

    Coeli M. Hoover; James E. Smith

    2016-01-01

    Background: In 2014, Chojnacky et al. published a revised set of biomass equations for trees of temperate US forests, expanding on an existing equation set (published in 2003 by Jenkins et al.), both of which were developed from published equations using a meta-analytical approach. Given the similarities in the approach to developing the equations, an examination of...

  20. Silvicultural manipulation and site effect on above and belowground biomass equations for young Pinus radiata

    International Nuclear Information System (INIS)

    Rubilar, Rafael A.; Allen, H. Lee; Alvarez, Jose S.; Albaugh, Timothy J.; Fox, Thomas R.; Stape, Jose L.

    2010-01-01

    There is little understanding of how silvicultural treatments, during the early stages of tree development, affect allometric relationships. We developed and compared stem, branch, foliage, coarse and fine root biomass, and leaf area estimation equations, for four-year-old genetically improved radiata pine trees grown on three contrasting soil-site conditions. At each site, selected trees were destructively sampled from a control (shovel planted, no weed control, fertilized with 2 g of boron), a shovel planted + weed control (2 first years) + complete fertilization (nitrogen + phosphorus + boron 2 first years + potassium 2nd year), and a soil tillage (subsoil at 60 cm) + weed control (first 2 years) + complete fertilization treatment. Tissues were separated into foliage, branch, stem, fine and coarse roots (>2 mm). Regression equations for each tree biomass tissue versus leaf area were fit for each site and compared among treatments and sites with the same genetic material. Our results indicated that individual tree biomasses for young plantations are affected by silvicultural treatment and site growing conditions. Higher variability in estimates was found for foliage and branches due to the ephemeral nature of these components. Stem biomass equations vary less, but differences in biomass equations were found among sites and treatments. Coarse root biomass estimates were variable but less than expected, considering the gradient among sites. Similar to stem biomass, a simple positive general linear relationship between root collar diameter, or diameter at breast height with coarse roots biomass was developed across sites and treatments.

  1. A regression approach for Zircaloy-2 in-reactor creep constitutive equations

    International Nuclear Information System (INIS)

    Yung Liu, Y.; Bement, A.L.

    1977-01-01

    In this paper the methodology of multiple regressions as applied to Zircaloy-2 in-reactor creep data analysis and construction of constitutive equation are illustrated. While the resulting constitutive equation can be used in creep analysis of in-reactor Zircaloy structural components, the methodology itself is entirely general and can be applied to any creep data analysis. The promising aspects of multiple regression creep data analysis are briefly outlined as follows: (1) When there are more than one variable involved, there is no need to make the assumption that each variable affects the response independently. No separate normalizations are required either and the estimation of parameters is obtained by solving many simultaneous equations. The number of simultaneous equations is equal to the number of data sets. (2) Regression statistics such as R 2 - and F-statistics provide measures of the significance of regression creep equation in correlating the overall data. The relative weights of each variable on the response can also be obtained. (3) Special regression techniques such as step-wise, ridge, and robust regressions and residual plots, etc., provide diagnostic tools for model selections. Multiple regression analysis performed on a set of carefully selected Zircaloy-2 in-reactor creep data leads to a model which provides excellent correlations for the data. (Auth.)

  2. Creep constitutive equation of dual phase 9Cr-ODS steel

    International Nuclear Information System (INIS)

    Sakasegawa, Hideo; Ukai, Shigeharu; Tamura, Manabu; Ohtsuka, Satoshi; Tanigawa, Hiroyasu; Ogiwara, Hiroyuki; Kohyama, Akira; Fujiwara, Masayuki

    2008-01-01

    9Cr-ODS (oxide dispersion strengthened) steels developed by JAEA (Japan Atomic Energy Agency) have superior creep properties compared with conventional heat resistant steels. The ODS steels can enormously contribute to practical applications of fast breeder reactors and more attractive fusion reactors. Key issues are developments of material processing procedures for mass production and creep life prediction methods in present R and D. In this study, formulation of creep constitutive equation was performed against the backdrop. The 9Cr-ODS steel displaying an excellent creep property is a dual phase steel. The ODS steel is strengthened by the δ ferrite which has a finer dispersion of oxide particles and shows a higher hardness than the α' martensite. The δ ferrite functions as a reinforcement in the dual phase 9Cr-ODS steel. Its creep behavior is very unique and cannot be interpreted by conventional theories of heat resistant steels. Alternative qualitative model of creep mechanism was formulated at the start of this study using the results of microstructural observations. Based on the alternative creep mechanism model, a novel creep constitutive equation was formulated using the exponential type creep equation extended by a law of mixture

  3. Developing Biomass Equations for Western Hemlock and Red Alder Trees in Western Oregon Forests

    Science.gov (United States)

    Krishna Poudel; Hailemariam Temesgen

    2016-01-01

    Biomass estimates are required for reporting carbon, assessing feedstock availability, and assessing forest fire threat. We developed diameter- and height-based biomass equations for Western hemlock (Tsuga heterophylla (Raf.) Sarg.) and red alder (Alnus rubra Bong.) trees in Western Oregon. A system of component biomass...

  4. Allometric Equations for Estimating Biomass and Carbon Stocks in the Temperate Forests of North-Western Mexico

    Directory of Open Access Journals (Sweden)

    Benedicto Vargas-Larreta

    2017-07-01

    Full Text Available This paper presents new equations for estimating above-ground biomass (AGB and biomass components of seventeen forest species in the temperate forests of northwestern Mexico. A data set corresponding to 1336 destructively sampled oak and pine trees was used to fit the models. The generalized method of moments was used to simultaneously fit systems of equations for biomass components and AGB, to ensure additivity. In addition, the carbon content of each tree component was calculated by the dry combustion method, in a TOC analyser. The results of cross-validation indicated that the fitted equations accounted for on average 91%, 82%, 83% and 76% of the observed variance in stem wood and stem bark, branch and foliage biomass, respectively, whereas the total AGB equations explained on average 93% of the total observed variance in AGB. The inclusion of total height (h or diameter at breast height2 × total height (d2h as a predictor in the d-only based equations systems slightly improved estimates for stem wood, stem bark and total above-ground biomass, and greatly improved the estimates produced by the branch and foliage biomass equations. The predictive power of the proposed equations is higher than that of existing models for the study area. The fitted equations were used to estimate stand level AGB stocks from data on growing stock in 429 permanent sampling plots. Three machine-learning techniques were used to model the estimated stand level AGB and carbon contents; the selected models were used to map the AGB and carbon distributions in the study area, for which mean values of respectively 129.84 Mg ha−1 and 63.80 Mg ha−1 were obtained.

  5. Evaluation of high temperature mechanical properties and constitutive equation of austenitic stainless steels

    International Nuclear Information System (INIS)

    Blanchard, P.; Tortel, J.

    1986-07-01

    A large amount of experimental data on 17-12 Mo SPH (316 L SPH) stainless steel have been obtained during the last years. The aim of this paper is to illustrate by a few examples the work done in the constitutive equations area using this powerful data base. Numerous semiempirical equations have been developed to represent tensile, cyclic, creep or relaxation tests on 17-12 Mo SPH (316 L SPH) stainless steel used for building the primary loop of the SUPER PHENIX 1 reactor. These equations are necessary tools for building elastic analysis's rules. Some examples are given with specific applications. The qualitative and semiquantitative comparisons of the stress-strain behaviour (both uniaxial and biaxial) predicted by the most common constitutive equations with the actual behaviour of 17-12 Mo SPH (316 L SPH) steel, shed some light on the strengths and weaknesses of these equations. This comparison is presented and discussed. The way to more realistic equations is shown. A detailed and quantitative comparison of the capabilities of two models, the CHABOCHE model and the multilayer unified model, is presented

  6. Constitutive equation of butter at static loading

    Directory of Open Access Journals (Sweden)

    Šárka Nedomová

    2008-01-01

    Full Text Available This study focuses on the constitutive modelling of finite deformation in the commercially obtained butter (composition is 83 % of milk fat at the temperature 17–20 °C. The specimens from the butter (height L0=14.6 mm and diameter 20 mm have been compressed between two parallel metal plates at a fixed crosshead speed 20 mm/min using of the testing device TIRA TEST. The force F and the deformation ∆L are measured during compression and both quantities are recorded. The experimental records force F – displacement (deformation were obtained. These records have been transformed into stress–strain dependences and into true stress–true strain. The basic data on the strain behaviour of a butter under low strain rates have been obtained. Experimental results show that the behaviour of butter can be described by a hyperelastic material model. In this model, the quasi–static response is defined by compressible hyperelasticity, whereby the strain energy potential is assumed to be representable by a newly proposed polynomial series with three independent parameters. The material parameters in the constitutive model are determined from compression test. A comparison of predictions based on the proposed constitutive equation with experiments shows that the model is able to describe the strain behaviour of the butter examined.

  7. Developing a generalized allometric equation for aboveground biomass estimation

    Science.gov (United States)

    Xu, Q.; Balamuta, J. J.; Greenberg, J. A.; Li, B.; Man, A.; Xu, Z.

    2015-12-01

    A key potential uncertainty in estimating carbon stocks across multiple scales stems from the use of empirically calibrated allometric equations, which estimate aboveground biomass (AGB) from plant characteristics such as diameter at breast height (DBH) and/or height (H). The equations themselves contain significant and, at times, poorly characterized errors. Species-specific equations may be missing. Plant responses to their local biophysical environment may lead to spatially varying allometric relationships. The structural predictor may be difficult or impossible to measure accurately, particularly when derived from remote sensing data. All of these issues may lead to significant and spatially varying uncertainties in the estimation of AGB that are unexplored in the literature. We sought to quantify the errors in predicting AGB at the tree and plot level for vegetation plots in California. To accomplish this, we derived a generalized allometric equation (GAE) which we used to model the AGB on a full set of tree information such as DBH, H, taxonomy, and biophysical environment. The GAE was derived using published allometric equations in the GlobAllomeTree database. The equations were sparse in details about the error since authors provide the coefficient of determination (R2) and the sample size. A more realistic simulation of tree AGB should also contain the noise that was not captured by the allometric equation. We derived an empirically corrected variance estimate for the amount of noise to represent the errors in the real biomass. Also, we accounted for the hierarchical relationship between different species by treating each taxonomic level as a covariate nested within a higher taxonomic level (e.g. species contribution of each different covariate in estimating the AGB of trees. Lastly, we applied the GAE to an existing vegetation plot database - Forest Inventory and Analysis database - to derive per-tree and per-plot AGB estimations, their errors, and how

  8. Component biomass equations for black spruce in Maine

    Science.gov (United States)

    M. M. Czapowskyj; D. J. Robison; R. D. Briggs; E. H. White; E. H. White

    1985-01-01

    Component biomass prediction equations are presented for young black spruce (Picea mariana B.S.P. (Mill,:)) in northern Maine. A weighted least squares model was used to construct the eq~iationsfo r small trees from 1 to 15 cm d.b.h., and an ordinary least squares model for trees less than 2 m in height. A linearized allometric model was also tested but was not used....

  9. The Use of Nonlinear Constitutive Equations to Evaluate Draw Resistance and Filter Ventilation

    Directory of Open Access Journals (Sweden)

    Eitzinger B

    2014-12-01

    Full Text Available This study investigates by nonlinear constitutive equations the influence of tipping paper, cigarette paper, filter, and tobacco rod on the degree of filter ventilation and draw resistance. Starting from the laws of conservation, the path to the theory of fluid dynamics in porous media and Darcy's law is reviewed and, as an extension to Darcy's law, two different nonlinear pressure drop-flow relations are proposed. It is proven that these relations are valid constitutive equations and the partial differential equations for the stationary flow in an unlit cigarette covering anisotropic, inhomogeneous and nonlinear behaviour are derived. From these equations a system of ordinary differential equations for the one-dimensional flow in the cigarette is derived by averaging pressure and velocity over the cross section of the cigarette. By further integration, the concept of an electrical analog is reached and discussed in the light of nonlinear pressure drop-flow relations. By numerical calculations based on the system of ordinary differential equations, it is shown that the influence of nonlinearities cannot be neglected because variations in the degree of filter ventilation can reach up to 20% of its nominal value.

  10. A regression approach for zircaloy-2 in-reactor creep constitutive equations

    International Nuclear Information System (INIS)

    Yung Liu, Y.; Bement, A.L.

    1977-01-01

    In this paper the methodology of multiple regressions as applied to zircaloy-2 in-reactor creep data analysis and construction of constitutive equation are illustrated. While the resulting constitutive equation can be used in creep analysis of in-reactor zircaloy structural components, the methodology itself is entirely general and can be applied to any creep data analysis. From data analysis and model development point of views, both the assumption of independence and prior committment to specific model forms are unacceptable. One would desire means which can not only estimate the required parameters directly from data but also provide basis for model selections, viz., one model against others. Basic understanding of the physics of deformation is important in choosing the forms of starting physical model equations, but the justifications must rely on their abilities in correlating the overall data. The promising aspects of multiple regression creep data analysis are briefly outlined as follows: (1) when there are more than one variable involved, there is no need to make the assumption that each variable affects the response independently. No separate normalizations are required either and the estimation of parameters is obtained by solving many simultaneous equations. The number of simultaneous equations is equal to the number of data sets, (2) regression statistics such as R 2 - and F-statistics provide measures of the significance of regression creep equation in correlating the overall data. The relative weights of each variable on the response can also be obtained. (3) Special regression techniques such as step-wise, ridge, and robust regressions and residual plots, etc., provide diagnostic tools for model selections

  11. A constitutive equation for hot deformation range of 304 stainless steel considering grain sizes

    International Nuclear Information System (INIS)

    Parsa, M.H.; Ohadi, D.

    2013-01-01

    Highlights: • A hot deformation constitutive equation based on invariant theory is proposed. • Deformation variables are evaluated based on objectivity, entropy principle, etc. • Using hot compression tests, coefficients of equation have been found. • The ability of equation to show the variation of stress with strain is examined. - Abstract: A general constitutive equation based on the framework of invariant theory by consideration of hot deformation key variables and also the properties of the material such as initial grain size is presented in the current work. Soundness of the considered parameters to be used in the developed formula was initially verified based on the important axioms such as objectivity, entropy principle, and thermodynamics stability. To access the prediction ability of the method, the formula was simplified for the simple hot compression test. To evaluate the simplified formula, single-hit hot compression tests were carried out at the temperature range of 900–1100 °C under true strain rate of 0.01–1 s −1 on a AISI 304 stainless steel. The capability of proposed formula for reproducing the variation of flow stress with strain and the strain hardening rate with stress for the resultant flow stress data was examined. The good agreement between model predictions and actual results signified the applicability of this method as a general constitutive equation in hot deformation studies

  12. On formal structure of constitutive equations for materials exhibiting shape memory effects

    International Nuclear Information System (INIS)

    Dobovsek, I.

    2000-01-01

    A derivation of constitutive equations in a general three-dimensional setting is described, based on an additive decomposition of the rate of deformation tensor. The rate of deformation tensor is assumed to consist of an elastic part, a thermoelastic part, a plastic part, a part due to shape memory transformation, and a part due to phase transformation. The thermoelastic part due to thermoelastic coupling accounts for the influence of temperature near phase transformation, while the plastic part is taken in the form of classical J 2 flow theory of plasticity with combined isotropic and kinematic hardening, where the back stress represents a tensor of orientational microstresses. It is assumed that the phase transformation part depends on the first and the second invariant of the tensor of crystallographic distortion, on the deviatoric part of the stress tensor, and on a special evolution parameter describing the rate of forming of a new phase. The elastic part of the rate of deformation tensor is connected with the objective rate of Cauchy stress through the tensor of elastic compliance. As a result, a general form of derived constitutive equations exhibits a similar structure as constitutive relations in finite deformation plasticity. (orig.)

  13. Compatible above-ground biomass equations and carbon stock estimation for small diameter Turkish pine (Pinus brutia Ten.).

    Science.gov (United States)

    Sakici, Oytun Emre; Kucuk, Omer; Ashraf, Muhammad Irfan

    2018-04-15

    Small trees and saplings are important for forest management, carbon stock estimation, ecological modeling, and fire management planning. Turkish pine (Pinus brutia Ten.) is a common coniferous species and comprises 25.1% of total forest area of Turkey. Turkish pine is also important due to its flammable fuel characteristics. In this study, compatible above-ground biomass equations were developed to predict needle, branch, stem wood, and above-ground total biomass, and carbon stock assessment was also described for Turkish pine which is smaller than 8 cm diameter at breast height or shorter than breast height. Compatible biomass equations are useful for biomass prediction of small diameter individuals of Turkish pine. These equations will also be helpful in determining fire behavior characteristics and calculating their carbon stock. Overall, present study will be useful for developing ecological models, forest management plans, silvicultural plans, and fire management plans.

  14. Allometric equations for estimating aboveground biomass for common shrubs in northeastern California

    Science.gov (United States)

    Steve Huff; Martin Ritchie; H. Temesgen

    2017-01-01

    Selected allometric equations and fitting strategies were evaluated for their predictive abilities for estimating above ground biomass for seven species of shrubs common to northeastern California. Size classes for woody biomass were categorized as 1-h fuels (0.1–0.6 cm), 10-h fuels (0.6–2.5 cm), 100-h fuels (2.5–7.6 cm), and 1000-h fuels (greater than 7.7 cm in...

  15. Pan tropical biomass equations for Mexico's dry forests

    Directory of Open Access Journals (Sweden)

    José Návar

    2014-12-01

    Full Text Available This study reports a set of robust regional M-tree allometric equations for Mexico's tropical dry forests and their application to a forest inventory dataset for the States of Durango and Sinaloa, Mexico. Calculated M data from 15 reported equations were fitted, applied and validated for regional and global models. Proposed theoretical models, empirically derived equations, as well as global and local reported equations were fitted and applied to calculated M-tree data using wood specific gravity, diameter at breast height, and top height as exogenous variables. Empirically-derived, computer-based equations assessed the M-tree evaluations slightly better than the theoretical, the global and the local models. However, the theoretical models projected compatible M-tree values and deserve further attention once wood specific gravity data are collected in the field. Using the best fit equation, mean M plot density values of 30, 41 and 35 Mg ha-1 were estimated from 57 plots (1,600 m² each, 217 plots (1,000 m² each and 166 plots (1,000 m² each in the tropical dry forests of the States of Durango, Tiniaquis and Vado Hondo (Sinaloa, respectively. The large sample size, the richness of the tested allometric models, the economic and ecological importance of this data-source, and the spatial coverage of these equations made this dataset uniquely useful for biomass, charcoal, and other bio-energy estimations, as well as for understanding the inherent heterogeneity of the stand-structure in dynamic tropical forest environments.

  16. On some constitutive equations for inelastic materials and their application

    International Nuclear Information System (INIS)

    Valeva, V.V.; Karagiozova, D.D.; Baltov, A.A.; Hadjikov, L.M.

    1987-01-01

    The problems of the mechano-mathematical modelling of the behaviour of materials under irradiation become more topical with development of atomic energetics. Many protective and technological structures could be subjected to irradiation in case of operation or average. The irradiation affects the process of deformation by causing inelastic swelling of materials, it affects their physico-mechanical properties, i.e. it changes their elastic, plastic, viscous, thermal, etc. properties. This effect varies depending on the material. Due to this reason it is very important to indicate exactly the class of materials for which a mechano-mathematical model is created. Grounding on the analysis of experimental data about the behaviour of different types of steel used in nuclear reactors and on the existing models, the present paper proposes constitutive equations for inelastic materials which account temperature, strain rate and radiation effects. The thermodynamic theory of systems with internal state parameters is utilized and for the description of the radiation effects two scalar parameters are introduced - dose φ r and temperature θ r of irradiation. Problem of the behaviour of irradiated structure element in stress concentrator zone is solved on the basis of these constitutive equations and of Boundary Element Method (BEM). (orig.)

  17. Equations for predicting biomass of six introduced tree species, island of Hawaii

    Science.gov (United States)

    Thomas H. Schukrt; Robert F. Strand; Thomas G. Cole; Katharine E. McDuffie

    1988-01-01

    Regression equations to predict total and stem-only above-ground dry biomass for six species (Acacia melanoxylon, Albizio falcataria, Eucalyptus globulus, E. grandis, E. robusta, and E. urophylla) were developed by felling and measuring 2- to 6-year-old...

  18. The flow behavior and constitutive equation in isothermal compression of FGH4096-GH4133B dual alloy

    International Nuclear Information System (INIS)

    Liu, Yanhui; Yao, Zekun; Ning, Yongquan; Nan, Yang; Guo, Hongzhen; Qin, Chun; Shi, Zhifeng

    2014-01-01

    Highlights: • Hot compression behaviors of the FGH4096-GH4133B dual alloy were investigated. • Constitutive equation also represented deformation behavior of a dual alloy. • The effects of deformation activation energy on the microstructures were discussed. • Constitutive equation represented an accurate and precise estimate of flow stress. - Abstract: The electron beam welding of superalloy FGH4096 and GH4133B was conducted, and the cylindrical compression specimens were machined from the central part of the electron beam weldments. Isothermal compression tests were carried out on electron beam weldments FGH4096-GH4133B alloy at the temperatures of 1020–11140 °C (the nominal γ′-transus temperature is about 1080 °C) and the strain rates of 0.001–1.0 s −1 with the height reduction of 50%. True stress–true strain curves are sensitive to the deformation temperature and strain rate, and the flow stress decreases with the increasing deformation temperature and the decreasing strain rate. The true stress–true strain curves can indicate the intrinsic relationship between the flow stress and the thermal-dynamic behavior. The apparent activation energy of deformation at the strain of 0.6 was calculated to be 550 kJ/mol, and the apparent activation energy has a great effect on the microstructure. The constitutive equation that describes the flow stress as a function of strain rate and deformation temperature was proposed for modeling the hot deformation process of FGH4096-GH4133B electron beam weldments. The constitutive equation at the strain of 0.6 was established using the hyperbolic law. The relationship between the strain and the values of parameters was studied, and the cubic functions were built. The constitutive equation during the whole process can be obtained based on the parameters under different strains. Comparing the experimental flow stress and the calculated flow stress, the constitutive equation obtained in this paper can be very good

  19. Molecular representation of molar domain (volume), evolution equations, and linear constitutive relations for volume transport.

    Science.gov (United States)

    Eu, Byung Chan

    2008-09-07

    In the traditional theories of irreversible thermodynamics and fluid mechanics, the specific volume and molar volume have been interchangeably used for pure fluids, but in this work we show that they should be distinguished from each other and given distinctive statistical mechanical representations. In this paper, we present a general formula for the statistical mechanical representation of molecular domain (volume or space) by using the Voronoi volume and its mean value that may be regarded as molar domain (volume) and also the statistical mechanical representation of volume flux. By using their statistical mechanical formulas, the evolution equations of volume transport are derived from the generalized Boltzmann equation of fluids. Approximate solutions of the evolution equations of volume transport provides kinetic theory formulas for the molecular domain, the constitutive equations for molar domain (volume) and volume flux, and the dissipation of energy associated with volume transport. Together with the constitutive equation for the mean velocity of the fluid obtained in a previous paper, the evolution equations for volume transport not only shed a fresh light on, and insight into, irreversible phenomena in fluids but also can be applied to study fluid flow problems in a manner hitherto unavailable in fluid dynamics and irreversible thermodynamics. Their roles in the generalized hydrodynamics will be considered in the sequel.

  20. A generic validation methodology and its application to a set of multi-axial creep damage constitutive equations

    International Nuclear Information System (INIS)

    Xu Qiang

    2005-01-01

    A generic validation methodology for a set of multi-axial creep damage constitutive equations is proposed and its use is illustrated with 0.5Cr0.5Mo0.25V ferritic steel which is featured as brittle or intergranular rupture. The objective of this research is to develop a methodology to guide systematically assess the quality of a set of multi-axial creep damage constitutive equations in order to ensure its general applicability. This work adopted a total quality assurance approach and expanded as a Four Stages procedure (Theories and Fundamentals, Parameter Identification, Proportional Load, and Non-proportional load). Its use is illustrated with 0.5Cr0.5Mo0.25V ferritic steel and this material is chosen due to its industry importance, the popular use of KRH type of constitutive equations, and the available qualitative experimental data including damage distribution from notched bar test. The validation exercise clearly revealed the deficiencies existed in the KRH formulation (in terms of mathematics and physics of damage mechanics) and its incapability to predict creep deformation accurately. Consequently, its use should be warned, which is particularly important due to its wide use as indicated in literature. This work contributes to understand the rational for formulation and the quality assurance of a set of constitutive equations in creep damage mechanics as well as in general damage mechanics. (authors)

  1. On the constitutive law of environment assisted fatigue: The physical meaning of the Paris type equations. Pt. 1

    International Nuclear Information System (INIS)

    Krausz, K.; Wu Xijia; Krausz, A.S.; Lian Zhiwen

    1992-01-01

    Environment assisted fatigue crack growth is a complex of thermally activated processes. Accordingly, the framework for the expression of rational constitutive law is developed from fracture kinetics theory. The correlation of the constitutive law with the Paris equation is discussed and the empirical parameters in the Paris equation are expressed explicitly in terms of activation energy, stress intensity factor range, temperature, stress ratio, and other physically rigorous engineering quantities. The theory assures and facilitates, the rigorous quantitative evaluation of the effects of the microstructure: the constitutive law gives guidance to its measurement and expresses it in terms of energy-related quantities. (orig.) [de

  2. A unified inelastic constitutive equation in terms of anisotropic yield function

    International Nuclear Information System (INIS)

    Inoue, T.; Imatani, S.

    1989-01-01

    In order to describe the material behavior under complicated loading conditions, inelastic constitutive equations accounting for the plasticity-creep interaction have been proposed by several researchers. However, these models are developed to predict the hardening and/or softening phenomena during the inelastic deformation processes, and two important features still remain to be considered; material anisotropy induced by the prior deformation history and inelastic flow or, in another word, directionality of the inelastic strain rate. This paper deals with a unified constitutive model capable of expressing both the deformation-induced anisotropy and the anisotropic flow. In the first part of the paper, an anisotropic yield function which can simulate both the Bauschinger effect and the cross effect is proposed. Then, the excess stress theory is applied to a viscoplastic constitutive relationship so as to describe the plasticity-creep interaction behavior. The experimental verification is carried out for SUS304 stainless steel at 650 degrees C in a biaxial stress state. Moreover, a generalized flow rule of the inelastic strain rate is also developed, by which the description of the ratcheting process can be improved

  3. Simulating sympathetic detonation using the hydrodynamic models and constitutive equations

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Bo Hoon; Kim, Min Sung; Yoh, Jack J. [Dept. of Mechanical and Aerospace Engineering, Seoul National University, Seoul (Korea, Republic of); Sun, Tae Boo [Hanwha Corporation Defense Rand D Center, Daejeon (Korea, Republic of)

    2016-12-15

    A Sympathetic detonation (SD) is a detonation of an explosive charge by a nearby explosion. Most of times it is unintended while the impact of blast fragments or strong shock waves from the initiating donor explosive is the cause of SD. We investigate the SD of a cylindrical explosive charge (64 % RDX, 20 % Al, 16 % HTPB) contained in a steel casing. The constitutive relations for high explosive are obtained from a thermo-chemical code that provides the size effect data without the rate stick data typically used for building the rate law and equation of state. A full size SD test of eight pallet-packaged artillery shells is performed that provides the pressure data while the hydrodynamic model with proper constitutive relations for reactive materials and the fragmentation model for steel casing is conducted to replicate the experimental findings. The work presents a novel effort to accurately model and reproduce the sympathetic detonation event with a reduced experimental effort.

  4. Analyzing the uncertainties in use of forest-derived biomass equations for open-grown trees in agricultural land

    Science.gov (United States)

    Xinhua Zhou; Michele M. Schoeneberger; James R. Brandle; Tala N. Awada; Jianmin Chu; Derrel L. Martin; Jihong Li; Yuqiang Li; Carl W. Mize

    2014-01-01

    Quantifying carbon in agroforestry trees requires biomass equations that capture the growth differences (e.g., tree specific gravity and architecture) created in the more open canopies of agroforestry plantings compared with those generally encountered in forests. Whereas forest-derived equations are available, equations for open-grown trees are not. Data from...

  5. Hot workability of γ + α2 titanium aluminide: Development of processing map and constitutive equations

    International Nuclear Information System (INIS)

    Gupta, R.K.; Narayana Murty, S.V.S.; Pant, Bhanu; Agarwala, Vijaya; Sinha, P.P.

    2012-01-01

    Highlights: ► Deformation studies of five TiAl alloys carried out through processing map. ► DRX domain and superplastic domain identified in power efficiency map. ► Safe working zone for alloys found at 1223–1423 K at strain rates (10 −2 –10 −3 s −1 ). ► Strain rate sensitivity, activation energy, Zener Hollomon parameter (Z) are obtained. ► Constitutive equations derived and verified. DRX grain size correlated with Z. - Abstract: Gamma titanium alumindes are intermetallics, which have very narrow working range. Hot isothermal working is the most suitable process for hot working of alloy. Accordingly, hot isothermal compression test is carried out on reaction synthesized and homogenized titanium aluminide alloys at different temperatures and strain rates using Gleeble thermomechanical simulator. Three alloys of Ti48Al2Cr2Nb0.1B (atom%) have been used in the study. Stress–strain data obtained from the test has been used to construct processing map, which indicates the safe and unsafe working zone. Strain rate sensitivity and Zener–Hollomon parameter has been calculated. Further, constitutive equations have been generated and verified. It is found that alloy has good workability in the temperature range of 1223–1423 K at strain rates of 0.01–0.001 s −1 . In this range of parameters, the alloys nearly follow the constitutive equations.

  6. Creep-recovery constitutive equation and its time-independent limit

    International Nuclear Information System (INIS)

    Chang, S.J.

    1978-01-01

    The effect of strain recovery is taken into consideration in establishing a constitutive equation for metals at elevated temperatures. Internal state variables and Rice's flow potential are used in the representation. Growth law for the state variables is discussed and interpreted to be a more general form of the kinematic hardening condition. Yield condition is obtained from the flow law. Accordingly, the flow rule is established with the effect of the recovery mechanism, as a slightly general version of the time-independent theory with the kinematic hardening rule. In the discussion of the time-independent limit, the duration of time required for the inelastic strain to reach its saturated value is defined

  7. Determination of parameters for a stress-strain constitutive equation considering time-dependent behavior of Toki granite

    International Nuclear Information System (INIS)

    Hirano, Toru; Seno, Yasuhiro; Nakama, Shigeo; Okubo, Seisuke

    2008-01-01

    Toki granite was tested to obtain parameters for the constitutive equation. The testing method was uniaxial compressive loading at the moderate a constant strain rate that is decreased after yielding to obtain the complete stress-strain curve. In addition, two kinds of the strain rate were alternately switched to obtain the parameter n from one specimen. The n represents the strength time-dependence in the constitutive equation. The second parameter m can be obtained by fitting the experimental stress-strain curve to the calculated curve. The m accounts for the behavior after yielding. According to the results, Toki granite has n=52 and m=60, showing relatively weak time-dependence of creep failure. (author)

  8. Biomass estimates of freshwater zooplankton from length-carbon regression equations

    Directory of Open Access Journals (Sweden)

    Patrizia COMOLI

    2000-02-01

    Full Text Available We present length/carbon regression equations of zooplankton species collected from Lake Maggiore (N. Italy during 1992. The results are discussed in terms of the environmental factors, e.g. food availability, predation, controlling biomass production of particle- feeders and predators in the pelagic system of lakes. The marked seasonality in the length-standardized carbon content of Daphnia, and its time-specific trend suggest that from spring onward food availability for Daphnia population may be regarded as a simple decay function. Seasonality does not affect the carbon content/unit length of the two predator Cladocera Leptodora kindtii and Bythotrephes longimanus. Predation is probably the most important regulating factor for the seasonal dynamics of their carbon biomass. The existence of a constant factor to convert the diameter of Conochilus colonies into carbon seems reasonable for an organism whose population comes on quickly and just as quickly disappears.

  9. Development of multidimensional two-fluid model code ACE-3D for evaluation of constitutive equations

    Energy Technology Data Exchange (ETDEWEB)

    Ohnuki, Akira; Akimoto, Hajime [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Kamo, Hideki

    1996-11-01

    In order to perform design calculations for a passive safety reactor with good accuracy by a multidimensional two-fluid model, we developed an analysis code, ACE-3D, which can apply for evaluation of constitutive equations. The developed code has the following features: 1. The basic equations are based on 3-dimensional two-fluid model and the orthogonal or the cylindrical coordinate system can be selected. The fluid system is air-water or steam-water. 2. The basic equations are formulated by the finite-difference scheme of staggered mesh. The convection term is formulated by an upwind scheme and the diffusion term by a center-difference scheme. 3. Semi-implicit numerical scheme is adopted and the mass and the energy equations are treated equally in convergent steps for Jacobi equations. 4. The interfacial stress term consists of drag force, life force, turbulent dispersion force, wall force and virtual mass force. 5. A {kappa}-{epsilon} turbulent model for bubbly flow is incorporated as the turbulent model. The predictive capability of ACE-3D has been verified using a data-base for bubbly flow in a small-scale vertical pipe. In future, the constitutive equations will be improved with a data-base in a large vertical pipe developed in our laboratory and we have a plan to construct a reliable analytical tool through the improvement work, the progress of calculational speed with vector and parallel processing, the assessments for phase change terms and so on. This report describes the outline for the basic equations and the finite-difference equations in ACE-3D code and also the outline for the program structure. Besides, the results for the assessments of ACE-3D code for the small-scale pipe are summarized. (author)

  10. Development of multidimensional two-fluid model code ACE-3D for evaluation of constitutive equations

    International Nuclear Information System (INIS)

    Ohnuki, Akira; Akimoto, Hajime; Kamo, Hideki.

    1996-11-01

    In order to perform design calculations for a passive safety reactor with good accuracy by a multidimensional two-fluid model, we developed an analysis code, ACE-3D, which can apply for evaluation of constitutive equations. The developed code has the following features: 1. The basic equations are based on 3-dimensional two-fluid model and the orthogonal or the cylindrical coordinate system can be selected. The fluid system is air-water or steam-water. 2. The basic equations are formulated by the finite-difference scheme of staggered mesh. The convection term is formulated by an upwind scheme and the diffusion term by a center-difference scheme. 3. Semi-implicit numerical scheme is adopted and the mass and the energy equations are treated equally in convergent steps for Jacobi equations. 4. The interfacial stress term consists of drag force, life force, turbulent dispersion force, wall force and virtual mass force. 5. A κ-ε turbulent model for bubbly flow is incorporated as the turbulent model. The predictive capability of ACE-3D has been verified using a data-base for bubbly flow in a small-scale vertical pipe. In future, the constitutive equations will be improved with a data-base in a large vertical pipe developed in our laboratory and we have a plan to construct a reliable analytical tool through the improvement work, the progress of calculational speed with vector and parallel processing, the assessments for phase change terms and so on. This report describes the outline for the basic equations and the finite-difference equations in ACE-3D code and also the outline for the program structure. Besides, the results for the assessments of ACE-3D code for the small-scale pipe are summarized. (author)

  11. Development of equations for predicting Puerto Rican subtropical dry forest biomass and volume

    Science.gov (United States)

    Thomas J. Brandeis; Matthew Delaney; Bernard R. Parresol; Larry Royer

    2006-01-01

    Carbon accounting, forest health monitoring and sustainable management of the subtropical dry forests of Puerto Rico and other Caribbean Islands require an accurate assessment of forest aboveground biomass (AGB) and stem volume. One means of improving assessment accuracy is the development of predictive equations derived from locally collected data. Forest inventory...

  12. Method for calculating the variance and prediction intervals for biomass estimates obtained from allometric equations

    CSIR Research Space (South Africa)

    Kirton, A

    2010-08-01

    Full Text Available for calculating the variance and prediction intervals for biomass estimates obtained from allometric equations A KIRTON B SCHOLES S ARCHIBALD CSIR Ecosystem Processes and Dynamics, Natural Resources and the Environment P.O. BOX 395, Pretoria, 0001, South... intervals (confidence intervals for predicted values) for allometric estimates can be obtained using an example of estimating tree biomass from stem diameter. It explains how to deal with relationships which are in the power function form - a common form...

  13. Family differences in equations for predicting biomass and leaf area in Douglas-fir (Pseudotsuga menziesii var. menziesii).

    Science.gov (United States)

    J.B. St. Clair

    1993-01-01

    Logarithmic regression equations were developed to predict component biomass and leaf area for an 18-yr-old genetic test of Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco var. menziesii) based on stem diameter or cross-sectional sapwood area. Equations did not differ among open-pollinated families in slope, but intercepts...

  14. Phenomenological inelastic constitutive equations for SiC and SiC fibers under irradiation

    International Nuclear Information System (INIS)

    El-Azab, A.; Ghoniem, N.M.

    1994-01-01

    Experimental data on irradiation-induced dimensional changes and creep in β-SiC and SiC fibers is analyzed, with the objective of studying the constitutive behavior of these materials under high-temperature irradiation. The data analysis includes empirical representation of irradiation-induced dimensional changes in SiC matrix and SiC fibers as function of time and irradiation temperature. The analysis also includes formulation of simple scaling laws to extrapolate the existing data to fusion conditions on the basis of the physical mechanisms of radiation effects on crystalline solids. Inelastic constitutive equations are then developed for SCS-6 SiC fibers, Nicalon fibers and CVD SiC. The effects of applied stress, temperature, and irradiation fields on the deformation behavior of this class of materials are simultaneously represented. Numerical results are presented for the relevant creep functions under the conditions of the fusion reactor (ARIES IV) first wall. The developed equations can be used in estimating the macro mechanical properties of SiC-SiC composite systems as well as in performing time-dependent micro mechanical analysis that is relevant to slow crack growth and fiber pull-out under fusion conditions

  15. Allometric equations for estimating tree biomass in restored mixed-species Atlantic Forest stands

    Science.gov (United States)

    Lauro Rodrigues Nogueira; Vera Lex Engel; John A. Parrotta; Antonio Carlos Galvão de Melo; Danilo Scorzoni Ré

    2014-01-01

    Restoration of Atlantic Forests is receiving increasing attention because of its role in both biodiversity conservation and carbon sequestration for global climate change mitigation. This study was carried out in an Atlantic Forest restoration project in the south-central region of São Paulo State – Brazil to develop allometric equations to estimate tree biomass of...

  16. Constitutive equations for extensional flow of wormlike micelles : stability analysis of the Bautista-Manero model

    NARCIS (Netherlands)

    Boek, E.S.; Padding, J.T.; Anderson, V.J.; Tardy, P.M.J.; Crawshaw, J.P.; Pearson, J.R.A.

    2005-01-01

    We carry out a stability analysis of the Bautista-Manero (B-M) constitutive equations for extensional flow of wormlike micelles. We show that all solutions for the steady-state extensional viscosity ¿E are unstable when the elongational rates e exceed some critical value. In some cases the only real

  17. Allometric Equations for Aboveground and Belowground Biomass Estimations in an Evergreen Forest in Vietnam.

    Science.gov (United States)

    Nam, Vu Thanh; van Kuijk, Marijke; Anten, Niels P R

    2016-01-01

    Allometric regression models are widely used to estimate tropical forest biomass, but balancing model accuracy with efficiency of implementation remains a major challenge. In addition, while numerous models exist for aboveground mass, very few exist for roots. We developed allometric equations for aboveground biomass (AGB) and root biomass (RB) based on 300 (of 45 species) and 40 (of 25 species) sample trees respectively, in an evergreen forest in Vietnam. The biomass estimations from these local models were compared to regional and pan-tropical models. For AGB we also compared local models that distinguish functional types to an aggregated model, to assess the degree of specificity needed in local models. Besides diameter at breast height (DBH) and tree height (H), wood density (WD) was found to be an important parameter in AGB models. Existing pan-tropical models resulted in up to 27% higher estimates of AGB, and overestimated RB by nearly 150%, indicating the greater accuracy of local models at the plot level. Our functional group aggregated local model which combined data for all species, was as accurate in estimating AGB as functional type specific models, indicating that a local aggregated model is the best choice for predicting plot level AGB in tropical forests. Finally our study presents the first allometric biomass models for aboveground and root biomass in forests in Vietnam.

  18. Allometric Equations for Aboveground and Belowground Biomass Estimations in an Evergreen Forest in Vietnam.

    Directory of Open Access Journals (Sweden)

    Vu Thanh Nam

    Full Text Available Allometric regression models are widely used to estimate tropical forest biomass, but balancing model accuracy with efficiency of implementation remains a major challenge. In addition, while numerous models exist for aboveground mass, very few exist for roots. We developed allometric equations for aboveground biomass (AGB and root biomass (RB based on 300 (of 45 species and 40 (of 25 species sample trees respectively, in an evergreen forest in Vietnam. The biomass estimations from these local models were compared to regional and pan-tropical models. For AGB we also compared local models that distinguish functional types to an aggregated model, to assess the degree of specificity needed in local models. Besides diameter at breast height (DBH and tree height (H, wood density (WD was found to be an important parameter in AGB models. Existing pan-tropical models resulted in up to 27% higher estimates of AGB, and overestimated RB by nearly 150%, indicating the greater accuracy of local models at the plot level. Our functional group aggregated local model which combined data for all species, was as accurate in estimating AGB as functional type specific models, indicating that a local aggregated model is the best choice for predicting plot level AGB in tropical forests. Finally our study presents the first allometric biomass models for aboveground and root biomass in forests in Vietnam.

  19. Modification of Flow Stress Curves and Constitutive Equations During Hot Compression Deformation of 5083 Aluminum Alloy

    Directory of Open Access Journals (Sweden)

    FU Ping

    2017-08-01

    Full Text Available The flow stress behavior of 5083 aluminum alloy was investigated under hot compression deformation at 523-723K,strain rates of 0.01-10s-1 and true strains of 0-0.7 with Gleeble-3800 thermal simulator. Based on the heat transfer effect on alloy deformation heat effect, the flow stress curves were corrected. The results show that influence of heat conduction can not be neglected and becomes more obvious with the increase of true strain. The corrected flow stress has little influence on the peak stress, but the steady flow stress softening trends to be diminished to some degree. The flow stress can be predicted by the Zener-Hollomon parameters in the constitutive equation. The corrected measured value exhibits a good agreement with the flow stress predicted by the constitutive equation, and the average relative error is only 5.21%.

  20. New constitutive equations to describe infinitesimal elastic-plastic deformations

    International Nuclear Information System (INIS)

    Boecke, B.; Link, F.; Schneider, G.; Bruhns, O.T.

    1983-01-01

    A set of constitutive equations is presented to describe infinitesimal elastic-plastic deformations of austenitic steel in the range up to 600 deg C. This model can describe the hardening behaviour in the case of mechanical loading and hardening, and softening behaviour in the case of thermal loading. The loading path can be either monotonic or cyclic. For this purpose, the well-known isotropic hardening model is continually transferred into the kinematic model according to Prager, whereby suitable internal variables are chosen. The occurring process-dependent material functions are to be determined by uniaxial experiments. The hardening function g and the translation function c are determined by means of a linearized stress-strain behaviour in the plastic range, whereby a coupling condition must be taken into account. As a linear hardening process is considered to be too unrealistic, nonlinearity is achieved by introducing a small function w, the determination procedure of which is given. (author)

  1. Lignocellulose Biomass: Constitutive Polymers. Biological Processes of Lignin Degradation; Biomasa lignocelulosica, polimeros constitutivos. Procesos biologicos de degradacion de la lignina

    Energy Technology Data Exchange (ETDEWEB)

    Martin, C; Manzanares, P

    1994-07-01

    The structure of the lignocellulosic materials and the chemical composition of their main constitutive polymers, cellulose, hemicelluloses and lignin are described. The most promising transformation processes according to the type of biomass considered: hardwood, softwood an herbaceous and the perspectives of biotechnological processes for bio pulping, bio bleaching and effluents decolorisation in the paper pulp industry are also discussed. (Author) 7 refs.

  2. Comparison between the Norton - and Mukherjee constitutive equations in the determination of stress - strain analysis of a material under creep

    International Nuclear Information System (INIS)

    Bevilacqua, L.; Feijoo, R.A.; Freire, J.L.; Miranda, P.E.V. de; Monteiro, E.; Silveira, T.L. da; Taroco, E.

    1981-06-01

    The Norton and Mukherjee constitutive equations are used to approximate the experimental results of creep in AISI 304 steel. Both equations are applied to the stress-strain analysis of a rotating disk with a concentric circular hole. From the design point of view it is shown that the stresses obtained with both equations are equivalents, which is not true for the velocities. (Author) [pt

  3. Development of PARA-ID Code to Simulate Inelastic Constitutive Equations and Their Parameter Identifications for the Next Generation Reactor Designs

    International Nuclear Information System (INIS)

    Koo, Gyeong Hoi; Lee, J. H.

    2006-03-01

    The establishment of the inelastic analysis technology is essential issue for a development of the next generation reactors subjected to elevated temperature operations. In this report, the peer investigation of constitutive equations in points of a ratcheting and creep-fatigue analysis is carried out and the methods extracting the constitutive parameters from experimental data are established. To perform simulations for each constitutive model, the PARA-ID (PARAmeter-IDentification) computer program is developed. By using this code, various simulations related with the parameter identification of the constitutive models are carried out

  4. Stability of non-linear constitutive formulations for viscoelastic fluids

    CERN Document Server

    Siginer, Dennis A

    2014-01-01

    Stability of Non-linear Constitutive Formulations for Viscoelastic Fluids provides a complete and up-to-date view of the field of constitutive equations for flowing viscoelastic fluids, in particular on their non-linear behavior, the stability of these constitutive equations that is their predictive power, and the impact of these constitutive equations on the dynamics of viscoelastic fluid flow in tubes. This book gives an overall view of the theories and attendant methodologies developed independently of thermodynamic considerations as well as those set within a thermodynamic framework to derive non-linear rheological constitutive equations for viscoelastic fluids. Developments in formulating Maxwell-like constitutive differential equations as well as single integral constitutive formulations are discussed in the light of Hadamard and dissipative type of instabilities.

  5. Constitutive equations for energy balance evaluation in metals under inelastic deformation

    Science.gov (United States)

    Kostina, A.; Plekhov, O.; Venkatraman, B.

    2017-12-01

    The work is devoted to the development of constitutive equations for energy balance evaluation in plastically deformed metals. The evolution of the defect system is described by a previously obtained model based on the Boltzmann-Gibbs statistics. In the framework of this model, a collective behavior of mesodefect ensembles is taken into account by the introduction of an internal variable representing additional structural strain. This parameter enables the partition of plastic work into dissipated heat and stored energy. The proposed model is applied to energy balance calculation in a Ti-1Al-1Mn specimen subjected to cyclic loading. Simulation results have shown that the model is able to describe an upward trend in the stored energy value with the increase in the load ratio.

  6. Anisotropic constitutive equations for the viscoplastic behaviour of the single crystal superalloy CMSX-4

    International Nuclear Information System (INIS)

    Fleury, G.; Schubert, F.

    1997-09-01

    Nickel-base superalloy blades of the first rotor stage in a gas turbine have to withstand extremely severe thermomechanical loading conditions. Single crystal blades exhibit a highly anisotropic deformation behaviour and are subjected to triaxial stress fields induced by complex cooling systems. Consequently the prediction of their deformation behaviour requires constitutive equations based on multiaxial formulations. The microstructural evolution of γ/γ' superalloys during the service time modifies the material properties and has therefore to be taken into account in the constitutive equations. For the modelling of the anisotropic, viscoplastic behaviour of single crystal blades taking into account the evolution of the microstructure, a microstructure-dependent, orthotropic Hills potential, whose anisotropy coefficients are connected to the edge length of the γ'-particles, is applied. The prediction was validated by investigating the deformation behaviour of the superalloy CMSX-4 in the range of temperatures [750 C-950 C]. If the shape of γ'-particles remain cubic, for example, in creep testing at low temperatures (up to about 850 C), the microstructure-dependent potential leads to the cubic version of the Hills potential. The prediction is in good agreement with creep results for left angle 001 right angle - and left angle 111 right angle - orientated specimens but overestimates the creep resistance of left angle 011 right angle - orientated specimens. (orig.)

  7. Constitutive Modelling of Resins in the Stiffness Domain

    Science.gov (United States)

    Klasztorny, M.

    2004-09-01

    An analytic method for inverting the constitutive compliance equations of viscoelasticity for resins is developed. These equations describe the HWKK/H rheological model, which makes it possible to simulate, with a good accuracy, short-, medium- and long-term viscoelastic processes in epoxy and polyester resins. These processes are of first-rank reversible isothermal type. The time histories of deviatoric stresses are simulated with three independent strain history functions of fractional and normal exponential types. The stiffness equations are described by two elastic and six viscoelastic constants having a clear physic meaning (three long-term relaxation coefficients and three relaxation times). The time histories of axiatoric stresses are simulated as perfectly elastic. The inversion method utilizes approximate constitutive stiffness equations of viscoelasticity for the HWKK/H model. The constitutive compliance equations for the model are a basis for determining the exact complex shear stiffness, whereas the approximate constitutive stiffness equations are used for determining the approximate complex shear stiffness. The viscoelastic constants in the stiffness domain are derived by equating the exact and approximate complex shear stiffnesses. The viscoelastic constants are obtained for Epidian 53 epoxy and Polimal 109 polyester resins. The accuracy of the approximate constitutive stiffness equations are assessed by comparing the approximate and exact complex shear stiffnesses. The constitutive stiffness equations for the HWKK/H model are presented in uncoupled (shear/bulk) and coupled forms. Formulae for converting the constants of shear viscoelasticity into the constants of coupled viscoelasticity are given as well.

  8. Detailed modelling of biomass pyrolysis: biomass structure and composition

    International Nuclear Information System (INIS)

    Hugony, F.; Migliavacca, G.; Faravelli, T.; Ranzi, E.

    2007-01-01

    The research routes followed in the field of numerical modelling development for biomass devolatilization are here summarised. In this first paper a wide introduction concerning the description of the chemical nature of the main classes of compounds which constitute biomasses is reported, it is the starting point for the subsequent description of the developed models, described in the companion paper [it

  9. Aboveground Tree Biomass for Pinus ponderosa in Northeastern California

    Directory of Open Access Journals (Sweden)

    Todd A. Hamilton

    2013-03-01

    Full Text Available Forest managers need accurate biomass equations to plan thinning for fuel reduction or energy production. Estimates of carbon sequestration also rely upon such equations. The current allometric equations for ponderosa pine (Pinus ponderosa commonly employed for California forests were developed elsewhere, and are often applied without consideration potential for spatial or temporal variability. Individual-tree aboveground biomass allometric equations are presented from an analysis of 79 felled trees from four separate management units at Blacks Mountain Experimental Forest: one unthinned and three separate thinned units. A simultaneous set of allometric equations for foliage, branch and bole biomass were developed as well as branch-level equations for wood and foliage. Foliage biomass relationships varied substantially between units while branch and bole biomass estimates were more stable across a range of stand conditions. Trees of a given breast height diameter and crown ratio in thinned stands had more foliage biomass, but slightly less branch biomass than those in an unthinned stand. The observed variability in biomass relationships within Blacks Mountain Experimental Forest suggests that users should consider how well the data used to develop a selected model relate to the conditions in any given application.

  10. Some trends in constitutive equation model development for high-temperature behavior of fast-reactor structural alloys

    International Nuclear Information System (INIS)

    Pugh, C.E.; Robinson, D.N.

    1977-01-01

    The paper addresses some important features of the inelastic behavior of 2 1 / 4 Cr--1Mo steel and indicates a mathematical framework that is capable of representing these types of response. While the constitutive model discussed embraces capabilities beyond those of equations presently used in design analyses; their implementation into practicable analysis methods (such as finite-element programs) is more demanding. For example, in the case of slow time-dependent deformations, the equations governing accumulation of the inelastic strain components and the evolution of the tensorial state variable α are intimately coupled. A part of recommending any such model for use in design must be a quantitative assessment of the economic feasibility of implementation

  11. [Biomass allometric equations of nine common tree species in an evergreen broadleaved forest of subtropical China].

    Science.gov (United States)

    Zuo, Shu-di; Ren, Yin; Weng, Xian; Ding, Hong-feng; Luo, Yun-jian

    2015-02-01

    Biomass allometric equation (BAE) considered as a simple and reliable method in the estimation of forest biomass and carbon was used widely. In China, numerous studies focused on the BAEs for coniferous forest and pure broadleaved forest, and generalized BAEs were frequently used to estimate the biomass and carbon of mixed broadleaved forest, although they could induce large uncertainty in the estimates. In this study, we developed the species-specific and generalized BAEs using biomass measurement for 9 common broadleaved trees (Castanopsis fargesii, C. lamontii, C. tibetana, Lithocarpus glaber, Sloanea sinensis, Daphniphyllum oldhami, Alniphyllum fortunei, Manglietia yuyuanensis, and Engelhardtia fenzlii) of subtropical evergreen broadleaved forest, and compared differences in species-specific and generalized BAEs. The results showed that D (diameter at breast height) was a better independent variable in estimating the biomass of branch, leaf, root, aboveground section and total tree than a combined variable (D2 H) of D and H (tree height) , but D2H was better than D in estimating stem biomass. R2 (coefficient of determination) values of BAEs for 6 species decreased when adding H as the second independent variable into D- only BAEs, where R2 value for S. sinensis decreased by 5.6%. Compared with generalized D- and D2H-based BAEs, standard errors of estimate (SEE) of BAEs for 8 tree species decreased, and similar decreasing trend was observed for different components, where SEEs of the branch decreased by 13.0% and 20.3%. Therefore, the biomass carbon storage and its dynamic estimates were influenced largely by tree species and model types. In order to improve the accuracy of the estimates of biomass and carbon, we should consider the differences in tree species and model types.

  12. Root biomass production in populations of six rooted macrophytes in response to Cu exposure: intra-specific variability versus constitutive-like tolerance.

    Science.gov (United States)

    Marchand, L; Nsanganwimana, F; Lamy, J B; Quintela-Sabaris, C; Gonnelli, C; Colzi, I; Fletcher, T; Oustrière, N; Kolbas, A; Kidd, P; Bordas, F; Newell, P; Alvarenga, P; Deletic, A; Mench, M

    2014-10-01

    Intra-specific variability of root biomass production (RP) of six rooted macrophytes, i.e. Juncus effusus, Phragmites australis, Schoenoplectus lacustris, Typha latifolia, Phalaris arundinacea, and Iris pseudacorus grown from clones, in response to Cu exposure was investigated. Root biomass production varied widely for all these macrophytes in control conditions (0.08 μM) according to the sampling site. Root biomass production of T. latifolia and I. pseudacorus in the 2.5-25 μM Cu range depended on the sampling location but not on the Cu dose in the growth medium. For P. australis, J. effusus, S. lacustris, and P. arundinacea, an intra-specific variability of RP depending on both the sampling location and the Cu-dose was evidenced. This intra-specific variability of RP depending on the sampling location and of Cu-tolerance for these last four species suggests that Cu constitutive tolerance for all rooted macrophytes is not a species-wide trait but it exhibits variability for some species. Copyright © 2014 Elsevier Ltd. All rights reserved.

  13. Biomass equations for selected drought-tolerant eucalypts in South ...

    African Journals Online (AJOL)

    In the water-scarce environment of South Africa, drought-tolerant eucalypt species have the potential to contribute to the timber and biomass resource. Biomass functions are a necessary prerequisite to predict yield and carbon sequestration. In this study preliminary biomass models for Eucalyptus cladocalyx, ...

  14. Biomass Conversion

    Energy Technology Data Exchange (ETDEWEB)

    Decker, Steve [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Brunecky, Roman [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Lin, Chien-Yuan [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Amore, Antonella [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Wei, Hui [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Chen, Xiaowen [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Tucker, Melvin P [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Czernik, Stefan [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Sluiter, Amie D [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Zhang, Min [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Magrini, Kimberly A [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Himmel, Michael E [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Sheehan, John [Formerly NREL; Dayton, David C. [Formerly NREL; Bozell, Joseph J. [Formerly NREL; Adney, William S. [Formerly NREL; Aden, Andy [Formerly NREL; Hames, Bonnie [Formerly NREL; Thomas, Steven R. [Formerly NREL; Bain, Richard L. [Formerly NREL

    2017-08-02

    Biomass constitutes all the plant matter found on our planet, and is produced directly by photosynthesis, the fundamental engine of life on earth. It is the photosynthetic capability of plants to utilize carbon dioxide from the atmosphere that leads to its designation as a 'carbon neutral' fuel, meaning that it does not introduce new carbon into the atmosphere. This article discusses the life cycle assessments of biomass use and the magnitude of energy captured by photosynthesis in the form of biomass on the planet to appraise approaches to tap this energy to meet the ever-growing demand for energy.

  15. Spatial-temporal management zones for biomass moisture

    DEFF Research Database (Denmark)

    Fountas, S; Bochtis, Dionysis; Sørensen, Claus Aage Grøn

    Biomass handling operations (harvesting, raking, collection, and transportation) are critical operations within the agricultural production system since they constitute the first link in the biomass supply chain, a fact of substantial importance considering the increasingly involvement of biomass...

  16. Biomass estimation by allometric relationships, nutrients, and carbon associated to heart-of-palm plantations in Costa Rica

    International Nuclear Information System (INIS)

    Ares, A.; Boniche, Y.; Quesada, J.P.; Yost, R.; Molina, E.; Smyth, T.J.

    2002-01-01

    Peach palm (Bactris gasipaes) agroecosystems constitute a productive and sustainable land use for the humid tropics. Allometric methods allow to predict biomass non-destructively at any time and, subsequently, to determine the span of growth phases, biomass and nutrient pools, and economic yields. The overall goals of this study were to obtain and validate predictive functions of aboveground dry biomass, and to relate standing biomass with heart-of-palm yields as well. Towards this purpose, peach palm shoots were harvested and separated into components: foliage, petiole and stem, in the Atlantic region of Costa Rica. A non-linear seemingly unrelated regression (NSUR) procedure, which simultaneously fits the component equations that predict leaf, petiole and stem in order to assure biomass additivity, was used to generate the allometric equations. Basal diameter (BD) was a more effective predictor of biomass than height to the fork between the spear leaf and the first fully expanded leaf, total height and number of leaves. Regression models explained 70-89% of the variance in biomass components (foliage, petiole and stem) or total shoot biomass. Three growth stages were identified: establishment (0-1 years), fast growth (1-3 or 1-8 years depending on plant density) and maturity (> 8 years). Nutrient contents associated to above- and below-ground biomass were measured. For above-ground biomass nutrient contents were N (up to 150 kg ha-1)>K (up to 119 kg ha-1)>Ca (up to 45 kg ha-1)>Mg=S=P (between 15-17 kg ha-1). The below-ground biomass: above-ground biomass ratio increased with the plantation age [es

  17. A structure-based constitutive equation for filler-reinforced rubber-like networks and for the description of the Mullins effect

    Czech Academy of Sciences Publication Activity Database

    Meissner, Bohumil; Matějka, Libor

    2006-01-01

    Roč. 47, č. 23 (2006), s. 7997-8012 ISSN 0032-3861 R&D Projects: GA ČR GA203/05/2252 Institutional research plan: CEZ:AV0Z40500505 Keywords : elastomers * fillers * constitutive equation Subject RIV: CD - Macromolecular Chemistry Impact factor: 2.773, year: 2006

  18. A three-dimensional constitutive model for shape memory alloy

    International Nuclear Information System (INIS)

    Zhou, Bo; Yoon, Sung-Ho; Leng, Jin-Song

    2009-01-01

    Shape memory alloy (SMA) has a wide variety of practical applications due to its unique super-elasticity and shape memory effect. It is of practical interest to establish a constitutive model which predicts its phase transformation and mechanical behaviors. In this paper, a new three-dimensional phase transformation equation, which predicts the phase transformation behaviors of SMA, is developed based on the results of a differential scanning calorimetry (DSC) test. It overcomes both limitations: that Zhou's phase transformation equations fail to describe the phase transformation from twinned martensite to detwinned martensite of SMA and Brinson's phase transformation equation fails to express the influences of phase transformation peak temperatures on the phase transformation behaviors of SMA. A new three-dimensional constitutive equation, which predicts the mechanical behaviors associated with the super-elasticity and shape memory effect of SMA, is developed on the basis of thermodynamics and solid mechanics. Results of numerical simulations show that the new constitutive model, which includes the new phase transformation equation and constitutive equation, can predict the phase transformation and mechanical behaviors associated with the super-elasticity and shape memory effect of SMA precisely and comprehensively. It is proved that Brinson's constitutive model of SMA can be considered as one special case of the new constitutive model

  19. Biorefining of wheat straw: accounting for the distribution of mineral elements in pretreated biomass by an extended pretreatment-severity equation.

    Science.gov (United States)

    Le, Duy Michael; Sørensen, Hanne R; Knudsen, Niels Ole; Schjoerring, Jan K; Meyer, Anne S

    2014-01-01

    Mineral elements present in lignocellulosic biomass feedstocks may accumulate in biorefinery process streams and cause technological problems, or alternatively can be reaped for value addition. A better understanding of the distribution of minerals in biomass in response to pretreatment factors is therefore important in relation to development of new biorefinery processes. The objective of the present study was to examine the levels of mineral elements in pretreated wheat straw in response to systematic variations in the hydrothermal pretreatment parameters (pH, temperature, and treatment time), and to assess whether it is possible to model mineral levels in the pretreated fiber fraction. Principal component analysis of the wheat straw biomass constituents, including mineral elements, showed that the recovered levels of wheat straw constituents after different hydrothermal pretreatments could be divided into two groups: 1) Phosphorus, magnesium, potassium, manganese, zinc, and calcium correlated with xylose and arabinose (that is, hemicellulose), and levels of these constituents present in the fiber fraction after pretreatment varied depending on the pretreatment-severity; and 2) Silicon, iron, copper, aluminum correlated with lignin and cellulose levels, but the levels of these constituents showed no severity-dependent trends. For the first group, an expanded pretreatment-severity equation, containing a specific factor for each constituent, accounting for variability due to pretreatment pH, was developed. Using this equation, the mineral levels could be predicted with R(2) > 0.75; for some with R(2) up to 0.96. Pretreatment conditions, especially pH, significantly influenced the levels of phosphorus, magnesium, potassium, manganese, zinc, and calcium in the resulting fiber fractions. A new expanded pretreatment-severity equation is proposed to model and predict mineral composition in pretreated wheat straw biomass.

  20. Modelling tree biomasses in Finland

    Energy Technology Data Exchange (ETDEWEB)

    Repola, J.

    2013-06-01

    Biomass equations for above- and below-ground tree components of Scots pine (Pinus sylvestris L), Norway spruce (Picea abies [L.] Karst) and birch (Betula pendula Roth and Betula pubescens Ehrh.) were compiled using empirical material from a total of 102 stands. These stands (44 Scots pine, 34 Norway spruce and 24 birch stands) were located mainly on mineral soil sites representing a large part of Finland. The biomass models were based on data measured from 1648 sample trees, comprising 908 pine, 613 spruce and 127 birch trees. Biomass equations were derived for the total above-ground biomass and for the individual tree components: stem wood, stem bark, living and dead branches, needles, stump, and roots, as dependent variables. Three multivariate models with different numbers of independent variables for above-ground biomass and one for below-ground biomass were constructed. Variables that are normally measured in forest inventories were used as independent variables. The simplest model formulations, multivariate models (1) were mainly based on tree diameter and height as independent variables. In more elaborated multivariate models, (2) and (3), additional commonly measured tree variables such as age, crown length, bark thickness and radial growth rate were added. Tree biomass modelling includes consecutive phases, which cause unreliability in the prediction of biomass. First, biomasses of sample trees should be determined reliably to decrease the statistical errors caused by sub-sampling. In this study, methods to improve the accuracy of stem biomass estimates of the sample trees were developed. In addition, the reliability of the method applied to estimate sample-tree crown biomass was tested, and no systematic error was detected. Second, the whole information content of data should be utilized in order to achieve reliable parameter estimates and applicable and flexible model structure. In the modelling approach, the basic assumption was that the biomasses of

  1. Time-independent limit of a creep-recovery constitutive equation

    International Nuclear Information System (INIS)

    Chang, S.J.

    1984-01-01

    The effect of strain recovery is taken into consideration in ORNL efforts to establish unified constitutive equations for time-dependent plastic deformation for metals at elevated temperatures. Representation by internal state variables and Rice's flow potential are under consideration. Here the growth law for the internal state variables is discussed and interpreted in terms of a generalized form of the kinematic hardening condition of Prager. The yield condition is obtained from the flow potential representation of the inelastic strain rate. A consistency condition is derived from the yield condition and leads to a flow rule which assumes a slightly general form as compared with that of the classical plasticity due to the effect of strain recovery and the time-dependent property of the yield condition. Based on this representation, the time-independent limit is discussed. From a vanishing effect of recovery and a rate-independent limit for the yield condition at low temperature, this flow rule reduces to the well-known form of time-independent plasticity with a kinematic hardening condition. The duration of time (the characteristic time) required for the inelastic strain to reach its saturated value is defined for the inelastic loading condition. It provides the measure of a minimum duration of time which is required for a valid approximation made by the time-independent plasticity model

  2. Implementation of constitutive equations for creep damage mechanics into the ABAQUS finite element code - some practical cases in high temperature component design and life assessment

    International Nuclear Information System (INIS)

    Segle, P.; Samuelson, L.Aa.; Andersson, Peder; Moberg, F.

    1996-01-01

    Constitutive equations for creep damage mechanics are implemented into the finite element program ABAQUS using a user supplied subroutine, UMAT. A modified Kachanov-Rabotnov constitutive equation which accounts for inhomogeneity in creep damage is used. With a user defined material a number of bench mark tests are analyzed for verification. In the cases where analytical solutions exist, the numerical results agree very well. In other cases, the creep damage evolution response appear to be realistic in comparison with laboratory creep tests. The appropriateness of using the creep damage mechanics concept in design and life assessment of high temperature components is demonstrated. 18 refs

  3. Mo- and V-catalyzed transformation of biomass into high-value chemicals

    DEFF Research Database (Denmark)

    Nielsen, Lasse Bo; Dethlefsen, Johannes Rytter; Lupp, Daniel

    2014-01-01

    The possibility of converting biomass into higher-value chemicals has received increased attention over the last few years. If biomass could be converted into biofules or platform chemicals, then it could constitute a large source of renewable energy and economy for society.......The possibility of converting biomass into higher-value chemicals has received increased attention over the last few years. If biomass could be converted into biofules or platform chemicals, then it could constitute a large source of renewable energy and economy for society....

  4. [Compatible biomass models of natural spruce (Picea asperata)].

    Science.gov (United States)

    Wang, Jin Chi; Deng, Hua Feng; Huang, Guo Sheng; Wang, Xue Jun; Zhang, Lu

    2017-10-01

    By using nonlinear measurement error method, the compatible tree volume and above ground biomass equations were established based on the volume and biomass data of 150 sampling trees of natural spruce (Picea asperata). Two approaches, controlling directly under total aboveground biomass and controlling jointly from level to level, were used to design the compatible system for the total aboveground biomass and the biomass of four components (stem, bark, branch and foliage), and the total ground biomass could be estimated independently or estimated simultaneously in the system. The results showed that the R 2 of the one variable and bivariate compatible tree volume and aboveground biomass equations were all above 0.85, and the maximum value reached 0.99. The prediction effect of the volume equations could be improved significantly when tree height was included as predictor, while it was not significant in biomass estimation. For the compatible biomass systems, the one variable model based on controlling jointly from level to level was better than the model using controlling directly under total above ground biomass, but the bivariate models of the two methods were similar. Comparing the imitative effects of the one variable and bivariate compatible biomass models, the results showed that the increase of explainable variables could significantly improve the fitness of branch and foliage biomass, but had little effect on other components. Besides, there was almost no difference between the two methods of estimation based on the comparison.

  5. Well-posed two-temperature constitutive equations for stable dense fluid shock waves using molecular dynamics and generalizations of Navier-Stokes-Fourier continuum mechanics.

    Science.gov (United States)

    Hoover, Wm G; Hoover, Carol G

    2010-04-01

    Guided by molecular dynamics simulations, we generalize the Navier-Stokes-Fourier constitutive equations and the continuum motion equations to include both transverse and longitudinal temperatures. To do so we partition the contributions of the heat transfer, the work done, and the heat flux vector between the longitudinal and transverse temperatures. With shockwave boundary conditions time-dependent solutions of these equations converge to give stationary shockwave profiles. The profiles include anisotropic temperature and can be fitted to molecular dynamics results, demonstrating the utility and simplicity of a two-temperature description of far-from-equilibrium states.

  6. Hydrothermal liquefaction of biomass

    DEFF Research Database (Denmark)

    Toor, Saqib; Rosendahl, Lasse; Rudolf, Andreas

    2011-01-01

    This article reviews the hydrothermal liquefaction of biomass with the aim of describing the current status of the technology. Hydrothermal liquefaction is a medium-temperature, high-pressure thermochemical process, which produces a liquid product, often called bio-oil or bi-crude. During...... the hydrothermal liquefaction process, the macromolecules of the biomass are first hydrolyzed and/or degraded into smaller molecules. Many of the produced molecules are unstable and reactive and can recombine into larger ones. During this process, a substantial part of the oxygen in the biomass is removed...... by dehydration or decarboxylation. The chemical properties of bio-oil are highly dependent of the biomass substrate composition. Biomass constitutes of various components such as protein; carbohydrates, lignin and fat, and each of them produce distinct spectra of compounds during hydrothermal liquefaction...

  7. Constitutive relations for nuclear reactor core materials

    International Nuclear Information System (INIS)

    Zaverl, F. Jr.; Lee, D.

    1978-01-01

    A strain rate dependent constitutive equation is proposed which is capable of describing inelastic deformation behavior of anisotropic metals, such as Zircaloys, under complex loading conditions. The salient features of the constitutive equations are that they describe history dependent inelastic deformation behaviour of anisotropic metals under three-dimensional stress states in the presence of fast neutron flux. It is shown that the general form of the constitutive relations is consistent with experimental observations made under both unirradiated and irradiated conditions. The utility of the model is demonstrated by examining the analytical results obtained for a segment of tubing undergoing different loading histories in a reactor. (Auth.)

  8. Constitutive behavior of as-cast AA1050, AA3104, and AA5182

    Science.gov (United States)

    van Haaften, W. M.; Magnin, B.; Kool, W. H.; Katgerman, L.

    2002-07-01

    Recent thermomechanical modeling to calculate the stress field in industrially direct-chill (DC) cast-aluminum slabs has been successful, but lack of material data limits the accuracy of these calculations. Therefore, the constitutive behavior of three aluminum alloys (AA1050, AA3104, and AA5182) was determined in the as-cast condition using tensile tests at low strain rates and from room temperature to solidus temperature. The parameters of two constitutive equations, the extended Ludwik equation and a combination of the Sellars-Tegart equation with a hardening law, were determined. In order to study the effect of recovery, the constitutive behavior after prestraining at higher temperatures was also investigated. To evaluate the quantified constitutive equations, tensile tests were performed simulating the deformation and cooling history experienced by the material during casting. It is concluded that both constitutive equations perform well, but the combined hardening-Sellars-Tegart (HST) equation has temperature-independent parameters, which makes it easier to implement in a DC casting model. Further, the deformation history of the ingot should be taken into account for accurate stress calculations.

  9. Volume and biomass for curlleaf cercocarpus in Nevada

    Science.gov (United States)

    David C. Chojnacky

    1984-01-01

    Volume and biomass equations were developed for curlleaf cercocarpus (Cercocarpus ledifolius Nutt.) in the Egan and Schell Mountains near Ely, NV. The equations predict cubic foot volume of wood and bark for variable minimum branch diameters. Wood density factors are given to convert volume predictions to pounds of fiber biomass. The reliability of...

  10. Remote Characterization of Biomass Measurements: Case Study of Mangrove Forests

    Science.gov (United States)

    Fatoyinbo, Temilola E.

    2010-01-01

    Accurately quantifying forest biomass is of crucial importance for climate change studies. By quantifying the amount of above and below ground biomass and consequently carbon stored in forest ecosystems, we are able to derive estimates of carbon sequestration, emission and storage and help close the carbon budget. Mangrove forests, in addition to providing habitat and nursery grounds for over 1300 animal species, are also an important sink of biomass. Although they only constitute about 3% of the total forested area globally, their carbon storage capacity -- in forested biomass and soil carbon -- is greater than that of tropical forests (Lucas et al, 2007). In addition, the amount of mangrove carbon -- in the form of litter and leaves exported into offshore areas is immense, resulting in over 10% of the ocean's dissolved organic carbon originating from mangroves (Dittmar et al, 2006) The measurement of forest above ground biomass is carried out on two major scales: on the plot scale, biomass can be measured using field measurements through allometric equation derivation and measurements of forest plots. On the larger scale, the field data are used to calibrate remotely sensed data to obtain stand-wide or even regional estimates of biomass. Currently, biomass can be calculated using average stand biomass values and optical data, such as aerial photography or satellite images (Landsat, Modis, Ikonos, SPOT, etc.). More recent studies have concentrated on deriving forest biomass values using radar (JERS, SIR-C, SRTM, Airsar) and/or lidar (ICEsat/GLAS, LVIS) active remote sensing to retrieve more accurate and detailed measurements of forest biomass. The implementation of a generation of new active sensors (UAVSar, DesdynI, Alos/Palsar, TerraX) has prompted the development of new tecm'liques of biomass estimation that use the combination of multiple sensors and datasets, to quantify past, current and future biomass stocks. Focusing on mangrove forest biomass estimation

  11. Optimization of biomass-producing conditions of Micrococcus sp. S ...

    African Journals Online (AJOL)

    Then these three variables were optimized by Box-behnken experimental design and response surface methodology, and a multinomial equation was constructed to describe the correlation between the biomass production and the three tested variables. By solving to this equation, the predicted maximum biomass was ...

  12. Mixed-species allometric equations and estimation of aboveground biomass and carbon stocks in restoring degraded landscape in northern Ethiopia

    Science.gov (United States)

    Mokria, Mulugeta; Mekuria, Wolde; Gebrekirstos, Aster; Aynekulu, Ermias; Belay, Beyene; Gashaw, Tadesse; Bräuning, Achim

    2018-02-01

    Accurate biomass estimation is critical to quantify the changes in biomass and carbon stocks following the restoration of degraded landscapes. However, there is lack of site-specific allometric equations for the estimation of aboveground biomass (AGB), which consequently limits our understanding of the contributions of restoration efforts in mitigating climate change. This study was conducted in northwestern Ethiopia to develop a multi-species allometric equation and investigate the spatial and temporal variation of C-stocks following the restoration of degraded landscapes. We harvested and weighed 84 trees from eleven dominant species from six grazing exclosures and adjacent communal grazing land. We observed that AGB correlates significantly with diameter at stump height D 30 (R 2 = 0.78 P < 0.01), and tree height H (R 2 = 0.41, P < 0.05). Our best model, which includes D 30 and H as predictors explained 82% of the variations in AGB. This model produced the lowest bias with narrow ranges of errors across different diameter classes. Estimated C-stock showed a significant positive correlation with stem density (R 2 = 0.80, P < 0.01) and basal area (R 2 = 0.84, P < 0.01). At the watershed level, the mean C-stock was 3.8 (±0.5) Mg C ha-1. Plot-level C-stocks varied between 0.1 and 13.7 Mg C ha-1. Estimated C-stocks in three- and seven-year-old exclosures exceeded estimated C-stock in the communal grazing land by 50%. The species that contribute most to C-stocks were Leucaena sp. (28%), Calpurnia aurea (21%), Euclea racemosa (20.9%), and Dodonaea angustifolia (15.8%). The equations developed in this study allow monitoring changes in C-stocks and C-sequestration following the implementation of restoration practices in northern Ethiopia over space and time. The estimated C-stocks can be used as a reference against which future changes in C-stocks can be compared.

  13. Ratio equations for loblolly pine trees

    Science.gov (United States)

    Dehai Zhao; Michael Kane; Daniel Markewitz; Robert. Teskey

    2015-01-01

    The conversion factors (CFs) or expansion factors (EFs) are often used to convert volume to green or dry weight, or from one component biomass to estimate total biomass or other component biomass. These factors might be inferred from the previously developed biomass and volume equations with or without destructive sampling data. However, how the factors are related to...

  14. Obtention of the constitutive equation of hydride blisters in fuel cladding from nanoindentation tests

    Energy Technology Data Exchange (ETDEWEB)

    Martin Rengel, M.A., E-mail: mamartin.rengel@upm.es [E.T.S.I. Caminos, Canales y Puertos, Universidad Politécnica de Madrid, c/ Profesor Aranguren, 3, E-28040 Madrid (Spain); Gomez, F.J., E-mail: javier.gomez@amsimulation.com [Advanced Material Simulation, AMS, Bilbao (Spain); Rico, A., E-mail: alvaro.rico@urjc.es [DIMME, Universidad Rey Juan Carlos, Mostoles (Spain); Ruiz-Hervias, J. [E.T.S.I. Caminos, Canales y Puertos, Universidad Politécnica de Madrid, c/ Profesor Aranguren, 3, E-28040 Madrid (Spain); Rodriguez, J. [DIMME, Universidad Rey Juan Carlos, Mostoles (Spain)

    2017-04-15

    It is well known that the presence of hydrides in nuclear fuel cladding may reduce its mechanical and fracture properties. This situation may be worsened as a consequence of the formation of hydride blisters. These blisters are zones with an extremely high hydrogen concentration and they are usually associated to the oxide spalling which may occur at the outer surface of the cladding. In this work, a method which allows us to reproduce, in a reliable way, hydride blisters in the laboratory has been devised. Depth-sensing indentation tests with a spherical indenter were conducted on a hydride blister produced in the laboratory with the aim of measuring its mechanical behaviour. The plastic stress-strain curve of the hydride blister was calculated for first time by combining depth-sensing indentation tests results with an iterative algorithm using finite element simulations. The algorithm employed reduces, in each iteration, the differences between the numerical and the experimental results by modifying the stress-strain curve. In this way, an almost perfect adjustment of the experimental data was achieved after several iterations. The calculation of the constitutive equation of the blister from nanoindentation tests, may involve a lack of uniqueness. To evaluate it, a method based on the optimization of parameters of analytical equations has been proposed in this paper. An estimation of the error which involves this method is also provided.

  15. Comprehensive database of diameter-based biomass regressions for North American tree species

    Science.gov (United States)

    Jennifer C. Jenkins; David C. Chojnacky; Linda S. Heath; Richard A. Birdsey

    2004-01-01

    A database consisting of 2,640 equations compiled from the literature for predicting the biomass of trees and tree components from diameter measurements of species found in North America. Bibliographic information, geographic locations, diameter limits, diameter and biomass units, equation forms, statistical errors, and coefficients are provided for each equation,...

  16. Using constitutive equation gap method for identification of elastic material parameters: Technical insights and illustrations

    KAUST Repository

    Florentin, Éric

    2011-08-09

    The constitutive equation gap method (CEGM) is a well-known concept which, until now, has been used mainly for the verification of finite element simulations. Recently, CEGM-based functional has been proposed to identify local elastic parameters based on experimental full-field measurement. From a technical point of view, this approach requires to quickly describe a space of statically admissible stress fields. We present here the technical insights, inspired from previous works in verification, that leads to the construction of such a space. Then, the identification strategy is implemented and the obtained results are compared with the actual material parameters for numerically generated benchmarks. The quality of the identification technique is demonstrated that makes it a valuable tool for interactive design as a way to validate local material properties. © 2011 Springer-Verlag.

  17. A new constitutive equation for strain hardening and softening of fcc metals during severe plastic deformation

    International Nuclear Information System (INIS)

    Wei, W.; Wei, K.X.; Fan, G.J.

    2008-01-01

    The stress-strain relationship for strain hardening and softening of high-purity aluminum and copper, which were deformed by equal channel angular pressing (ECAP) at ambient temperature, was analyzed by combining the Estrin and Mecking (EM) model and an Avrami-type equation with experimental data during severe plastic deformation. The initial strain hardening can be described by the EM model, while the flow stress arrives at the peak stress after it was saturated. However, strain softening similar to plastic deformation at high temperatures is observed after the peak stress. Moreover, the peak strain at the maximum flow stress is ∼4 for copper and ∼2 for aluminum. A new constitutive equation was developed to describe strain softening at high strain levels, which was supported well by tensile, compression and microhardness tests at room temperature and low strain rate. It was observed that dynamic recovery and recrystallization occurs in copper, and recrystallized grains and their growth in aluminum. The results indicate that dynamic recovery and recrystallization was the dominant softening mechanism, which was confirmed by scanning electron microscopy-electron channeling contrast observations and the abnormal relationship between the imposed strain during ECAP and subsequent recrystallization temperature after ECAP

  18. A constitutive theory of reacting electrolyte mixtures

    Science.gov (United States)

    Costa Reis, Martina; Wang, Yongqi; Bono Maurizio Sacchi Bassi, Adalberto

    2013-11-01

    A constitutive theory of reacting electrolyte mixtures is formulated. The intermolecular interactions among the constituents of the mixture are accounted for through additional freedom degrees to each constituent of the mixture. Balance equations for polar reacting continuum mixtures are accordingly formulated and a proper set of constitutive equations is derived with basis in the Müller-Liu formulation of the second law of thermodynamics. Moreover, the non-equilibrium and equilibrium responses of the reacting mixture are investigated in detail by emphasizing the inner and reactive structures of the medium. From the balance laws and constitutive relations, the effects of molecular structure of constituents upon the fluid flow are studied. It is also demonstrated that the local thermodynamic equilibrium state can be reached without imposing that the set of independent constitutive variables is time independent, neither spatially homogeneous nor null. The resulting constitutive relations presented throughout this work are of relevance to many practical applications, such as swelling of clays, developing of bio and polymeric membranes, and use of electrorheological fluids in industrial processes. The first author acknowledges financial support from National Counsel of Technological and Scientific Development (CNPq) and German Academic Exchange Service (DAAD).

  19. Multiaxial probabilistic elastic-plastic constitutive simulations of soils

    Science.gov (United States)

    Sadrinezhad, Arezoo

    Fokker-Planck-Kolmogorov (FPK) equation approach has recently been developed to simulate elastic-plastic constitutive behaviors of materials with uncertain material properties. The FPK equation approach transforms the stochastic constitutive rate equation, which is a stochastic, nonlinear, ordinary differential equation (ODE) in the stress-pseudo time space into a second-order accurate, deterministic, linear FPK partial differential equation (PDE) in the probability density of stress-pseudo time space. This approach does not suffer from the drawbacks of the traditional approaches such as the Monte Carlo approach and the perturbation approach for solving nonlinear ODEs with random coefficients. In this study, the existing one dimensional FPK framework for probabilistic constitutive modeling of soils is extended to multi--dimension. However, the multivariate FPK PDEs cannot be solved using the traditional mathematical techniques such as finite difference techniques due to their high computational cost. Therefore, computationally efficient algorithms based on the Fourier spectral approach are developed for solving a class of FPK PDEs that arises in probabilistic elasto-plasticity. This class includes linear FPK PDEs in (stress) space and (pseudo) time - having space-independent but time-dependent, and both space- and time-dependent coefficients - with impulse initial conditions and reflecting boundary conditions. The solution algorithms, rely on first mapping the stress space of the governing PDE between 0 and 2pi using the change of coordinates rule, followed by approximating the solution of the PDE in the 2pi-periodic domain by a finite Fourier series in the stress space and unknown time-dependent solution coefficients. Finally, the time-dependent solution coefficients are obtained from the initial condition. The accuracy and efficiency of the developed algorithms are tested. The developed algorithms are used to simulate uniaxial and multiaxial, monotonic and cyclic

  20. Estimating volume, biomass, and potential emissions of hand-piled fuels

    Science.gov (United States)

    Clinton S. Wright; Cameron S. Balog; Jeffrey W. Kelly

    2009-01-01

    Dimensions, volume, and biomass were measured for 121 hand-constructed piles composed primarily of coniferous (n = 63) and shrub/hardwood (n = 58) material at sites in Washington and California. Equations using pile dimensions, shape, and type allow users to accurately estimate the biomass of hand piles. Equations for estimating true pile volume from simple geometric...

  1. Creep constitutive equations for a 0.5Cr 0.5 Mo 0.25V ferritic steel in the temperature range 565 deg. C-675 deg. C

    International Nuclear Information System (INIS)

    Mustata, R.; Hayhurst, D.R.

    2005-01-01

    A two damage state variable model is used to describe the softening mechanisms, damage initiation and growth for a low alloy ferritic steel 1/2Cr-1/2Mo-1/4V at 565 and 590 deg. C within the Continuum Damage Mechanics framework. The level of complexity of the constitutive equations and the degree of coupling through damage is high and it is difficult to calibrate values of the constitutive constants without recourse to optimisation techniques. A methodology for the analysis of uni-axial experimental data, coupled with a traditional gradient-based optimisation technique, is presented for the unique determination of the constitutive constants. Two sets of experimental data on parent material are used for inversion purposes: at 565 deg. C, c.f. Cane [Cane BJ. Collaborative programme on the corelation of test data for high temperature design of welded steam pipes. Presentation and analysis of the material data. Note No. RD/L/2101N81, March, CEGB Laboratory; 1981]; and, at 590 deg. C, c.f. Miller [Miller DA. Private communication: 'Creep rupture testing of Cr M V pipe steel. ERA Project 63-01-040320009'. Barnwood, Gloucs, UK: British Energy; 2000]. The variation of the constitutive parameters with temperature in the range 565-590 deg. C has been deduced by considering the values of constitutive parameters for the same alloy deduced by Perrin and Hayhurst [Perrin IJ, Hayhurst DR. Creep constitutive equations for a 0.5Cr-0.5Mo-0.25V ferritic steel in the temperature range 600-675 deg. C. J Strain Anal 1996;31:299-314] in the temperature range 620-675 deg. C

  2. Biomasse et stocks de carbone des forêts tropicales africaines (synthèse bibliographique

    Directory of Open Access Journals (Sweden)

    Loubota Panzou, GJ.

    2016-01-01

    Full Text Available Biomass and carbon stocks of tropical African forests. A review. Introduction. Quantifying the biomass and carbon stocks contained in tropical forests has become an international priority for the implementation of the REDD+ mechanism. Forest biomass is estimated at three successive levels: the tree, the stand and the region level. This paper reviews the state of the art regarding the estimation of biomass and carbon stocks in tropical African forests. Literature. This review highlights the fact that very few allometric equations, equations used for estimating the biomass of the tree using non-destructive measurements (diameter, height, have been established for tropical African forests. At the stand level, the review highlights the spatial and temporal variations in biomass between forest types in Central and Eastern Africa. While biomass recovery after a disturbance (logging, for instance is rather quick, a great deal of uncertainty still remains regarding the spatial variation in biomass, and there is no consensus on a regional biomass map. The quality of biomass mapping in tropical Africa strongly depends on the type of remotely-sensed data being used (optical, RADAR or LIDAR, and the allometric equation used to convert forest inventory data into biomass. Conclusions. Based on the lack of precision of the available allometric equations and forest inventory data and the large spatial scale involved, many uncertainties persist in relation to the estimation of the biomass and carbon stocks contained in African tropical forests.

  3. Biorefining of wheat straw: accounting for the distribution of mineral elements in pretreated biomass by an extended pretreatment – severity equation

    DEFF Research Database (Denmark)

    Le, Duy Michael; Sørensen, Hanne Risbjerg; Knudsen, Niels Ole

    2014-01-01

    Background: Mineral elements present in lignocellulosic biomass feedstocks may accumulate in biorefinery process streams and cause technological problems, or alternatively can be reaped for value addition. A better understanding of the distribution of minerals in biomass in response to pretreatment...... factors is therefore important in relation to development of new biorefinery processes. The objective of the present study was to examine the levels of mineral elements in pretreated wheat straw in response to systematic variations in the hydrothermal pretreatment parameters (pH, temperature......) Silicon, iron, copper, aluminum correlated with lignin and cellulose levels, but the levels of these constituents showed no severity-dependent trends. For the first group, an expanded pretreatment-severity equation, containing a specific factor for each constituent, accounting for variability due...

  4. Constitutive Equation and Hot Compression Deformation Behavior of Homogenized Al–7.5Zn–1.5Mg–0.2Cu–0.2Zr Alloy

    Directory of Open Access Journals (Sweden)

    Jianliang He

    2017-10-01

    Full Text Available The deformation behavior of homogenized Al–7.5Zn–1.5Mg–0.2Cu–0.2Zr alloy has been studied by a set of isothermal hot compression tests, which were carried out over the temperature ranging from 350 °C to 450 °C and the strain rate ranging from 0.001 s−1 to 10 s−1 on Gleeble-3500 thermal simulation machine. The associated microstructure was studied using electron back scattered diffraction (EBSD and transmission electron microscopy (TEM. The results showed that the flow stress is sensitive to strain rate and deformation temperature. The shape of true stress-strain curves obtained at a low strain rate (≤0.1 s−1 conditions shows the characteristic of dynamic recrystallization (DRX. Two Arrhenius-typed constitutive equation without and with strain compensation were established based on the true stress-strain curves. Constitutive equation with strain compensation has more precise predictability. The main softening mechanism of the studied alloy is dynamic recovery (DRV accompanied with DRX, particularly at deformation conditions, with low Zener-Holloman parameters.

  5. Biomass equations and biomass expansion factors (BEFs) for pine (pinus spp.), spruce (picea spp.) and broadleaved dominated stands in Norway

    OpenAIRE

    Viken, Knut Ole

    2012-01-01

    Abstract The objectives of this study were (1) to develop models for estimation of stand-level tree biomass for spruce (picea spp.)- pine (pinus spp.)- and broadleaved-dominated forest in Norway and, (2) develop biomass expansion factors (BEFs; ratio of stem volume to biomass) which convert stem volume to whole tree biomass for Norwegian forest conditions. A dataset from a 5 year period (2006 – 2010) from the Norwegian National Forest Inventory (NFI) were used to develop the...

  6. Rheological behavior and constitutive equations of heterogeneous titanium-bearing molten slag

    Science.gov (United States)

    Jiang, Tao; Liao, De-ming; Zhou, Mi; Zhang, Qiao-yi; Yue, Hong-rui; Yang, Song-tao; Duan, Pei-ning; Xue, Xiang-xin

    2015-08-01

    Experimental studies on the rheological properties of a CaO-SiO2-Al2O3-MgO-TiO2-(TiC) blast furnace (BF) slag system were conducted using a high-temperature rheometer to reveal the non-Newtonian behavior of heterogeneous titanium-bearing molten slag. By measuring the relationships among the viscosity, the shear stress and the shear rate of molten slags with different TiC contents at different temperatures, the rheological constitutive equations were established along with the rheological parameters; in addition, the non-Newtonian fluid types of the molten slags were determined. The results indicated that, with increasing TiC content, the viscosity of the molten slag tended to increase. If the TiC content was less than 2wt%, the molten slag exhibited the Newtonian fluid behavior when the temperature was higher than the critical viscosity temperature of the molten slag. In contrast, the molten slag exhibited the non-Newtonian pseudoplastic fluid characteristic and the shear thinning behavior when the temperature was less than the critical viscosity temperature. However, if the TiC content exceeded 4wt%, the molten slag produced the yield stress and exhibited the Bingham and plastic pseudoplastic fluid behaviors when the temperature was higher and lower than the critical viscosity temperature, respectively. When the TiC content increased further, the yield stress of the molten slag increased and the shear thinning phenomenon became more obvious.

  7. Influence of constitutive equations and calculation methods on the results of inelastic analysis of benchmark problems

    International Nuclear Information System (INIS)

    Konter, A.W.A.; Kusters, G.M.A.

    1981-01-01

    Several constitutive equations are used to analyse the structural behaviour of a simply supported beam and circular plate loaded at its center, both tested at 1100 0 F. The time-independent plastic behaviour has been analysed with the isotropic and kinematic hardening model as well as with the ORNL 10th cycle model and the fraction model of Besseling. The time-dependent creep behaviour has been analysed using the isotropic hardening rules and the ORNL auxiliary hardening rules. No interaction of the creep and plastic behaviour was taken into account. Especially for cyclic loading conditions, large differences occur in the predictions of the inelastic behaviour. Good agreement between theory and prediction can be obtained with models which accurately account for the ratio of kinematic and saturating isotropic hardening of the used material. (orig./HP)

  8. Identification of the parameters of an elastic material model using the constitutive equation gap method

    KAUST Repository

    Florentin, Éric

    2010-04-23

    Today, the identification ofmaterialmodel parameters is based more and more on full-field measurements. This article explains how an appropriate use of the constitutive equation gap method (CEGM) can help in this context. The CEGM is a well-known concept which, until now, has been used mainly for the verification of finite element simulations. This has led to many developments, especially concerning the techniques for constructing statically admissible stress fields. The originality of the present study resides in the application of these recent developments to the identification problem. The proposed CEGM is described in detail, then evaluated through the identification of heterogeneous isotropic elastic properties. The results obtained are systematically compared with those of the equilibrium gap method, which is a well-known technique for the resolution of such identification problems. We prove that the use of the enhanced CEGM significantly improves the quality of the results. © Springer-Verlag 2010.

  9. Hierarchical models for informing general biomass equations with felled tree data

    Science.gov (United States)

    Brian J. Clough; Matthew B. Russell; Christopher W. Woodall; Grant M. Domke; Philip J. Radtke

    2015-01-01

    We present a hierarchical framework that uses a large multispecies felled tree database to inform a set of general models for predicting tree foliage biomass, with accompanying uncertainty, within the FIA database. Results suggest significant prediction uncertainty for individual trees and reveal higher errors when predicting foliage biomass for larger trees and for...

  10. Biomass Thermochemical Conversion Program: 1986 annual report

    Energy Technology Data Exchange (ETDEWEB)

    Schiefelbein, G.F.; Stevens, D.J.; Gerber, M.A.

    1987-01-01

    Wood and crop residues constitute a vast majority of the biomass feedstocks available for conversion, and thermochemical processes are well suited for conversion of these materials. Thermochemical conversion processes can generate a variety of products such as gasoline hydrocarbon fuels, natural gas substitutes, or heat energy for electric power generation. The US Department of Energy is sponsoring research on biomass conversion technologies through its Biomass Thermochemical Conversion Program. Pacific Northwest Laboratory has been designated the Technical Field Management Office for the Biomass Thermochemical Conversion Program with overall responsibility for the Program. This report briefly describes the Thermochemical Conversion Program structure and summarizes the activities and major accomplishments during fiscal year 1986. 88 refs., 31 figs., 5 tabs.

  11. Biomass production and carbon storage of Populus ×canadensis ...

    African Journals Online (AJOL)

    euramericana (Dode) Guinier ex Piccarolo) clone I-214 have good potential for biomass production. The objective of the study was estimation of biomass using allometric equations and estimation of carbon allocation according to tree components.

  12. Family forest owner preferences for biomass harvesting in Massachusetts

    Science.gov (United States)

    Marla Markowski-Lindsay; Thomas Stevens; David B. Kittredge; Brett J. Butler; Paul Catanzaro; David Damery

    2012-01-01

    U.S. forests, including family-owned forests, are a potential source of biomass for renewable energy. Family forest owners constitute a significant portion of the overall forestland in the U.S., yet little is known about family forest owners' preferences for supplying wood-based biomass. The goal of this study is to understand how Massachusetts family forest...

  13. Zeolite-catalyzed biomass conversion to fuels and chemicals

    DEFF Research Database (Denmark)

    Taarning, Esben; Osmundsen, Christian Mårup; Yang, Xiaobo

    2011-01-01

    Heterogeneous catalysts have been a central element in the efficient conversion of fossil resources to fuels and chemicals, but their role in biomass utilization is more ambiguous. Zeolites constitute a promising class of heterogeneous catalysts and developments in recent years have demonstrated...... their potential to find broad use in the conversion of biomass. In this perspective we review and discuss the developments that have taken place in the field of biomass conversion using zeolites. Emphasis is put on the conversion of lignocellulosic material to fuels using conventional zeolites as well...

  14. A constitutive model for concrete under dynamic loading

    International Nuclear Information System (INIS)

    Suaris, W.; Shah, S.P.

    1983-01-01

    A continuous damage theory for the quasistatic and dynamic behaviour of concrete is presented. The continuous damage theory is rational choice for use in predicing the dynamic behaviour of concrete as the strain-rate effects that have been observed for concrete can to a large extent be attributed to the rate-sensitivity of the microcracking process. A vectorial representation is adopted for the damage to account for the planar nature of the microcracks in concrete. Damage is treated as an internal state variable influencing the free energy of the material and the constitutive equations and the damage evolution equations are derived consistently using thermodynamic considerations. The developed constitutive model is then calibrated by using test results in flexure and compression over a range of strain-rates. The constitutive model is also shown to be capable of predicting certain other experimentally observed characteristics of the dynamic response of concrete. (orig./HP)

  15. The one-parameter-model - a constitutive equation applied to a heat resistant alloy

    International Nuclear Information System (INIS)

    Schwarze, E.; Schuster, H.; Nickel, H.

    1992-01-01

    In the present work a constitutive model earlier developed and used to predict experimental results of hot tests and fatigue tests from creep experiments of metallic materials were modified to comply with the properties of a high temperature resistant material. The improved model accounts for the properties of a material developing a density and a structure of dislocation lines which are capable of interactions with particles (carbides) from a second phase. The time and temperature dependent evolution of the carbide structure has been described by an equation which explains the formation of seeds as well as their growths (Ostwald ripening). The extended model was applied to Incoloy 800H which is known to develop a carbide structure. Therefore hot tensile and fatigue tests, creep and relaxation experiments using the heats ADU and BAK (KFA specifications) at temperature between 800deg C and 900deg C were performed including both solution treated specimens and specimens heat treated for 10, 100 and 1000 hours. As compared with the results from tensile tests where the carbide structures play a subordinated role, alternately, these structures have a decisive influence on the creep properties of specimens during the primary creep phase, i.e. low stresses and high temperatures. (orig.) [de

  16. A study on creep-fatigue life analysis using a unified constitutive equation and a continuous damage law

    International Nuclear Information System (INIS)

    Hiroe, Tetsuyuki; Igari, Toshihide; Nakajima, Keiichi

    1986-01-01

    A newly developed type of life analysis is introduced using a unified constitutive equation and a continuous damage law on 2 1/4Cr - 1Mo steel at 600 deg C. the viscoplasticity theory based on total strain and overstress used for the rate effect at room temperature is extended for application to the inelastic analysis at elevated temperature, and the extended uniaxial model is shown to reproduce the inelastic stress and strain behavior with a strain rate change observed in the experiment. The incremental life prediction law is employed and its coupling with the viscoplasticity model produces both an inelastic stress-strain response and the damage accumulation, simultaneously and continuously. The life prediction for creep, fatigue and creep-fatigue loading shows good correspondence with the experimental data. (author)

  17. The constitutive distributed parameter model of multicomponent chemical processes in gas, fluid and solid phase

    International Nuclear Information System (INIS)

    Niemiec, W.

    1985-01-01

    In the literature of distributed parameter modelling of real processes is not considered the class of multicomponent chemical processes in gas, fluid and solid phase. The aim of paper is constitutive distributed parameter physicochemical model, constructed on kinetics and phenomenal analysis of multicomponent chemical processes in gas, fluid and solid phase. The mass, energy and momentum aspects of these multicomponent chemical reactions and adequate phenomena are utilized in balance operations, by conditions of: constitutive invariance for continuous media with space and time memories, reciprocity principle for isotropic and anisotropic nonhomogeneous media with space and time memories, application of definitions of following derivative and equation of continuity, to the construction of systems of partial differential constitutive state equations, in the following derivative forms for gas, fluid and solid phase. Couched in this way all physicochemical conditions of multicomponent chemical processes in gas, fluid and solid phase are new form of constitutive distributed parameter model for automatics and its systems of equations are new form of systems of partial differential constitutive state equations in sense of phenomenal distributed parameter control

  18. Limitations of constitutive relations for TiNi shape memory alloys

    International Nuclear Information System (INIS)

    Tang, W.; Sandstroem, R.

    1995-01-01

    Phase transformation tensor Ω in the constitutive equation proposed by Tanaka has been evaluated by employing experimental data of TiNi alloys in a constrained recovery process. It demonstrates that the absolute value of Ω for the constrained recovery process is typically about 0.6 ∼ 0.7 x 10 3 MPa, which is much smaller than that for the stress - induced martensitic transformation (typically 2.5 ∼ 3.5 x 10 3 ). Based on the evaluated results for Ω, predicted recovery stress - temperature relations by the constitutive equation are compared with the experimental data for TiNi rods under different strains. Big discrepancy exists for large strain conditions. Several transformation kinetic expressions are examined for the constitutive relation of the constrained recovery process. (orig.)

  19. CFD Studies on Biomass Thermochemical Conversion

    Directory of Open Access Journals (Sweden)

    Lifeng Yan

    2008-06-01

    Full Text Available Thermochemical conversion of biomass offers an efficient and economically process to provide gaseous, liquid and solid fuels and prepare chemicals derived from biomass. Computational fluid dynamic (CFD modeling applications on biomass thermochemical processes help to optimize the design and operation of thermochemical reactors. Recent progression in numerical techniques and computing efficacy has advanced CFD as a widely used approach to provide efficient design solutions in industry. This paper introduces the fundamentals involved in developing a CFD solution. Mathematical equations governing the fluid flow, heat and mass transfer and chemical reactions in thermochemical systems are described and sub-models for individual processes are presented. It provides a review of various applications of CFD in the biomass thermochemical process field.

  20. Allometric biomass equations for 12 tree species in coniferous and broadleaved mixed forests, Northeastern China.

    Science.gov (United States)

    He, Huaijiang; Zhang, Chunyu; Zhao, Xiuhai; Fousseni, Folega; Wang, Jinsong; Dai, Haijun; Yang, Song; Zuo, Qiang

    2018-01-01

    Understanding forest carbon budget and dynamics for sustainable resource management and ecosystem functions requires quantification of above- and below-ground biomass at individual tree species and stand levels. In this study, a total of 122 trees (9-12 per species) were destructively sampled to determine above- and below-ground biomass of 12 tree species (Acer mandshuricum, Acer mono, Betula platyphylla, Carpinus cordata, Fraxinus mandshurica, Juglans mandshurica, Maackia amurensis, P. koraiensis, Populus ussuriensis, Quercus mongolica, Tilia amurensis and Ulmus japonica) in coniferous and broadleaved mixed forests of Northeastern China, an area of the largest natural forest in the country. Biomass allocation was examined and biomass models were developed using diameter as independent variable for individual tree species and all species combined. The results showed that the largest biomass allocation of all species combined was on stems (57.1%), followed by coarse root (21.3%), branch (18.7%), and foliage (2.9%). The log-transformed model was statistically significant for all biomass components, although predicting power was higher for species-specific models than for all species combined, general biomass models, and higher for stems, roots, above-ground biomass, and total tree biomass than for branch and foliage biomass. These findings supplement the previous studies on this forest type by additional sample trees, species and locations, and support biomass research on forest carbon budget and dynamics by management activities such as thinning and harvesting in the northeastern part of China.

  1. Modeling flow stress constitutive behavior of SA508-3 steel for nuclear reactor pressure vessels

    Energy Technology Data Exchange (ETDEWEB)

    Sun Mingyue, E-mail: mysun@imr.ac.cn [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China); Luhan, Hao; Shijian, Li; Dianzhong, Li; Yiyi, Li [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China)

    2011-11-15

    Highlights: > A series of flow stress constitutive equations for SA508-3 steel were successfully established. > The experimental results under different conditions have validated the constitutive equations. > An industrial application of the model was present to simulate a large conical shell forging process. - Abstract: Based on the measured stress-strain curves under different temperatures and strain rates, a series of flow stress constitutive equations for SA508-3 steel were firstly established through the classical theories on work hardening and softening. The comparison between the experimental and modeling results has confirmed that the established constitutive equations can correctly describe the mechanical responses and microstructural evolutions of the steel under various hot deformation conditions. We further represented a successful industrial application of this model to simulate a forging process for a large conical shell used in a nuclear steam generator, which evidences its practical and promising perspective of our model with an aim of widely promoting the hot plasticity processing for heavy nuclear components of fission reactors.

  2. A fundamental review of the relationships between nanotechnology and lignocellulosic biomass

    Science.gov (United States)

    Theodore Wegner; E. Philip Jones

    2009-01-01

    At first glance, the relationship between nanotechnology and lignocellulosic biomass may seem to be unconnected or at best tenuously connected. It is important to recognize that. at a fundamental level, lignocellulosic biomass is made up of nanometer-size constitutive building block units that provide valuable properties to wood and other types of renewable...

  3. EXTENSIÓN DE UNA ECUACIÓN CONSTITUTIVA HIPOPLÁSTICA PARA SIMULAR ENSAYOS TRIAXIALES CÍCLICOS EXTENSION OF A HYPOPLASTIC CONSTITUTIVE EQUATION TO SIMULATE CYCLIC TRIAXIAL TESTS

    Directory of Open Access Journals (Sweden)

    Hugo Alexander Rondón Quintana

    2010-08-01

    Full Text Available La ecuación constitutiva hipoplástica es una herramienta matemática que puede simular de manera confiable el comportamiento que experimentan materiales granulares no tratados (GNT bajo carga estática y monotónica. Sin embargo, para el caso de cargas cíclicas, como las que ocurren en un pavimento, la ecuación sobreestima la acumulación de las deformaciones permanentes. En el presente artículo se presenta una versión extendida de la ecuación constitutiva hipoplástica de Wolffersdorff (1996 (una de las más utilizadas actualmente en el mundo que intenta mejorar dicha limitación. Adicionalmente se presenta la simulación de ensayos triaxiales cíclicos con presión de confinamiento constante y variable (los cuales son los más utilizados en el mundo para estudiar el comportamiento de GNT en pavimentos utilizando la versión extendida. Las simulaciones realizadas demuestran la amplia capacidad que tiene la ecuación hipoplástica para reproducir el comportamiento que el material granular experimenta en los ensayos cíclicos.Hypoplastic constitutive equation is a mathematical tool which offers the possibility to reliably simulate unbound granular materials (UGM behavior under static and monotonic loads. However, such equation overestimates the permanent strain accumulation under cyclic loads (e.g. in a pavement structure. This paper presents an extension of the Wolffersdorff's Hypoplastic constitutive equation (1996 (currently one of the most used equations, aiming for improving its performance under cyclic loads. Beside this, cyclic triaxial tests simulations are presented using the extended version with constant and variable confining pressures. Triaxial tests are the most used when studying UGM behavior in pavements. Simulation results demonstrated the ability of the proposed equation for reproducing the behavior of granular materials under cyclic tests.

  4. Allometric models for estimating the aboveground biomass of the mangrove Rhizophora mangle

    Directory of Open Access Journals (Sweden)

    Heide Vanessa Souza Santos

    Full Text Available Abstract The development of species-specific allometric models is critical to the improvement of aboveground biomass estimates, as well as to the estimation of carbon stock and sequestration in mangrove forests. This study developed allometric equations for estimating aboveground biomass of Rhizophora mangle in the mangroves of the estuary of the São Francisco River, in northeastern Brazil. Using a sample of 74 trees, simple linear regression analysis was used to test the dependence of biomass (total and per plant part on size, considering both transformed (ln and not-transformed data. Best equations were considered as those with the lowest standard error of estimation (SEE and highest adjusted coefficient of determination (R2a. The ln-transformed equations showed better results, with R2a near 0.99 in most cases. The equations for reproductive parts presented low R2a values, probably attributed to the seasonal nature of this compartment. "Basal Area2 × Height" showed to be the best predictor, present in most of the best-fitted equations. The models presented here can be considered reliable predictors of the aboveground biomass of R. mangle in the NE-Brazilian mangroves as well as in any site were this widely distributed species present similar architecture to the trees used in the present study.

  5. Non-Destructive, Laser-Based Individual Tree Aboveground Biomass Estimation in a Tropical Rainforest

    Directory of Open Access Journals (Sweden)

    Muhammad Zulkarnain Abd Rahman

    2017-03-01

    Full Text Available Recent methods for detailed and accurate biomass and carbon stock estimation of forests have been driven by advances in remote sensing technology. The conventional approach to biomass estimation heavily relies on the tree species and site-specific allometric equations, which are based on destructive methods. This paper introduces a non-destructive, laser-based approach (terrestrial laser scanner for individual tree aboveground biomass estimation in the Royal Belum forest reserve, Perak, Malaysia. The study area is in the state park, and it is believed to be one of the oldest rainforests in the world. The point clouds generated for 35 forest plots, using the terrestrial laser scanner, were geo-rectified and cleaned to produce separate point clouds for individual trees. The volumes of tree trunks were estimated based on a cylinder model fitted to the point clouds. The biomasses of tree trunks were calculated by multiplying the volume and the species wood density. The biomasses of branches and leaves were also estimated based on the estimated volume and density values. Branch and leaf volumes were estimated based on the fitted point clouds using an alpha-shape approach. The estimated individual biomass and the total above ground biomass were compared with the aboveground biomass (AGB value estimated using existing allometric equations and individual tree census data collected in the field. The results show that the combination of a simple single-tree stem reconstruction and wood density can be used to estimate stem biomass comparable to the results usually obtained through existing allometric equations. However, there are several issues associated with the data and method used for branch and leaf biomass estimations, which need further improvement.

  6. Biomass thermochemical conversion program. 1985 annual report

    Energy Technology Data Exchange (ETDEWEB)

    Schiefelbein, G.F.; Stevens, D.J.; Gerber, M.A.

    1986-01-01

    Wood and crop residues constitute a vast majority of the biomass feedstocks available for conversion, and thermochemical processes are well suited for conversion of these materials. The US Department of Energy (DOE) is sponsoring research on this conversion technology for renewable energy through its Biomass Thermochemical Conversion Program. The Program is part of DOE's Biofuels and Municipal Waste Technology Division, Office of Renewable Technologies. This report briefly describes the Thermochemical Conversion Program structure and summarizes the activities and major accomplishments during fiscal year 1985. 32 figs., 4 tabs.

  7. Modeling flow stress constitutive behavior of SA508-3 steel for nuclear reactor pressure vessels

    International Nuclear Information System (INIS)

    Sun Mingyue; Hao Luhan; Li Shijian; Li Dianzhong; Li Yiyi

    2011-01-01

    Highlights: → A series of flow stress constitutive equations for SA508-3 steel were successfully established. → The experimental results under different conditions have validated the constitutive equations. → An industrial application of the model was present to simulate a large conical shell forging process. - Abstract: Based on the measured stress-strain curves under different temperatures and strain rates, a series of flow stress constitutive equations for SA508-3 steel were firstly established through the classical theories on work hardening and softening. The comparison between the experimental and modeling results has confirmed that the established constitutive equations can correctly describe the mechanical responses and microstructural evolutions of the steel under various hot deformation conditions. We further represented a successful industrial application of this model to simulate a forging process for a large conical shell used in a nuclear steam generator, which evidences its practical and promising perspective of our model with an aim of widely promoting the hot plasticity processing for heavy nuclear components of fission reactors.

  8. Constitutive modelling in the range of inelastic deformations

    International Nuclear Information System (INIS)

    Bruhns, O.T.; White, P.S.; Chaboche, J.L.; Eikhoff, J.V.D.

    1988-01-01

    The main objective of this report is to describe the state of the art in constitutive modelling in the range of inelastic deformations, with particular consideration of the practical use of these models in the field of fast reactors, rather than to formulate new models. An outline is given of the constitutive equations for high-temperature reactor materials developed at the Oak Ridge National Laboratory. Two forms of equations are considered, a semi-classical treatment in terms of separate plasticity and creep and unified equations in which the classical plasticity does not explicitly occur. The fraction model originally proposed by Besseling is described. The basic concept of this model is that the material is thought to be subdivided into a number of parallel fractions, each with simple conventional properties. The more complicated behaviour of real material is thus approximated by choosing a number of parallel fractions with suitable models and model parameters. Three time-independent formulations of plasticity are considered and compared. Attention is focused on the kinematic hardening in the multi-yield surface theory of Mroz and the non-linear kinematic rule intensively used at Enset and Onera. Some connections are pointed out with the two-surface model of Dafalias and Popov, and the range of applicability of the different models is studied in detail. Finally, the constitutive equations of the Interatom model are presented. They are mainly based on the concept of overstresses, expressing the rate-dependence of the material by the magnitude of these overstresses. This model furthermore comprises a combination of general non-linear isotropic and kinematic hardening, with a smooth transition from isotropic to kinematic hardening as a function of process time

  9. A modified parallel constitutive model for elevated temperature flow behavior of Ti-6Al-4V alloy based on multiple regression

    Energy Technology Data Exchange (ETDEWEB)

    Cai, Jun; Shi, Jiamin; Wang, Kuaishe; Wang, Wen; Wang, Qingjuan; Liu, Yingying [Xi' an Univ. of Architecture and Technology, Xi' an (China). School of Metallurgical Engineering; Li, Fuguo [Northwestern Polytechnical Univ., Xi' an (China). School of Materials Science and Engineering

    2017-07-15

    Constitutive analysis for hot working of Ti-6Al-4V alloy was carried out by using experimental stress-strain data from isothermal hot compression tests. A new kind of constitutive equation called a modified parallel constitutive model was proposed by considering the independent effects of strain, strain rate and temperature. The predicted flow stress data were compared with the experimental data. Statistical analysis was introduced to verify the validity of the developed constitutive equation. Subsequently, the accuracy of the proposed constitutive equations was evaluated by comparing with other constitutive models. The results showed that the developed modified parallel constitutive model based on multiple regression could predict flow stress of Ti-6Al-4V alloy with good correlation and generalization.

  10. The compressive behaviour and constitutive equation of polyimide foam in wide strain rate and temperature

    Directory of Open Access Journals (Sweden)

    Yoshimoto Akifumi

    2015-01-01

    Full Text Available These days, polymer foams, such as polyurethane foam and polystyrene foam, are used in various situations as a thermal insulator or shock absorber. In general, however, their strength is insufficient in high temperature environments because of their low glass transition temperature. Polyimide is a polymer which has a higher glass transition temperature and high strength. Its mechanical properties do not vary greatly, even in low temperature environments. Therefore, polyimide foam is expected to be used in the aerospace industry. Thus, the constitutive equation of polyimide foam that can be applied across a wide range of strain rates and ambient temperature is very useful. In this study, a series of compression tests at various strain rates, from 10−3 to 103 s−1 were carried out in order to examine the effect of strain rate on the compressive properties of polyimide foam. The flow stress of polyimide foam increased rapidly at dynamic strain rates. The effect of ambient temperature on the properties of polyimide foam was also investigated at temperature from − 190 °C to 270°∘C. The flow stress decreased with increasing temperature.

  11. Constitutive representation of damage development and healing in WIPP salt

    International Nuclear Information System (INIS)

    Chan, K.S.; Bodner, S.R.; Fossum, A.F.; Munson, D.E.

    1994-01-01

    There has been considerable interest in characterizing and modeling the constitutive behavior of rock salt with particular reference to long-term creep and creep failure. The interest is motivated by the projected use of excavated rooms in salt rock formations as repositories for nuclear waste. It is presumed that closure of those rooms by creep ultimately would encapsulate the waste material, resulting in its effective isolation. A continuum mechanics approach for treating damage healing is formulated as part of a constitutive model for describing coupled creep, fracture, and healing in rock salt. Formulation of the healing term is, described and the constitutive model is evaluated against experimental data of rock salt from the Waste Isolation Pilot Plant (WIPP) site. The results indicate that healing anistropy in WIPP salt can be modeled with an appropriate power-conjugate equivalent stress, kinetic equation, and evolution equation for damage healing

  12. Constitutive modelling of sandvik 1RK91

    NARCIS (Netherlands)

    Datta, K.; Datta, K.; Hommes, M.; Post, J.; Geijselaers, Hubertus J.M.; Huetink, Han; Beyer, J.; Onate, E; Owen, D.R.J

    2003-01-01

    A physically based constitutive equation is being developed for the maraging stainless steel Sandvik 1RK91. The steel is used to make precision parts. These parts are formed through multistage forming operations and heat treatments from cold rolled and annealed sheets. The specific alloy is designed

  13. Basic equations of interfacial area transport in gas-liquid two-phase flow

    International Nuclear Information System (INIS)

    Kataoka, I.; Yoshida, K.; Naitoh, M.; Okada, H.; Morii, T.

    2011-01-01

    The rigorous and consistent formulations of basic equations of interfacial area transport were derived using correlation functions of characteristic function of each phase and velocities of each phase. Turbulent transport term of interfacial area concentration was consistently derived and related to the difference between interfacial velocity and averaged velocity of each phase. Constitutive equations of turbulent transport terms of interfacial area concentration were proposed for bubbly flow. New transport model and constitutive equations were developed for churn flow. These models and constitutive equations are validated by experimental data of radial distributions of interfacial area concentration in bubbly and churn flow. (author)

  14. Time-Delay Effects on Constitutive Gene Expression*

    International Nuclear Information System (INIS)

    Feng Yan-Ling; Wang Dan; Tang Xu-Lei; Dong Jian-Min

    2017-01-01

    The dynamics of constitutive gene expression with delayed mRNA degradation is investigated, where the intrinsic noise caused by the small number of reactant molecules is introduced. It is found that the oscillatory behavior claimed in previous investigations does not appear in the approximation of small time delay, and the steady state distribution still follows the Poisson law. Furthermore, we introduce the extrinsic noise induced by surrounding environment to explore the effects of this noise and time delay on the Fano factor. Based on a delay Langevin equation and the corresponding Fokker–Planck equation, the distribution of mRNA copy-number is achieved analytically. The time delay and extrinsic noise play similar roles in the gene expression system, that is, they are able to result in the deviation of the Fano factor from 1 evidently. The measured Fano factor for constitutive gene expression is slightly larger than 1, which is perhaps attributed to the time-delay effect. (paper)

  15. Lidar-based biomass assessment for the Yukon River Basin

    Science.gov (United States)

    Peterson, B.; Wylie, B. K.; Stoker, J.; Nossov, D.

    2010-12-01

    Climate change is expected to have a significant impact on high-latitude forests in terms of their ability to sequester carbon as expressed as pools of standing total biomass and soil organic matter. Above ground biomass is an important driver in ecosystem process models used to assess, predict, and understand climate change impacts. Therefore, it is of compelling interest to acquire accurate assessments of current biomass levels for these high-latitude forests, a particular challenge because of their vastness and remoteness. At this time, remote sensing is the only feasible method through which to acquire such assessments. In this study, the use of lidar data for estimating shrub and tree biomass for the Yukon Flats region of Alaska’s Yukon River Basin (YRB) is demonstrated. The lidar data were acquired in the late summer and fall of 2009 as were an initial set of field sampling data collected for training and validation purposes. The 2009 field campaigns were located near Canvasback Lake and Boot Lake in the YRB. Various tallies of biomass were calculated from the field data using allometric equations (Bond-Lamberty et al. 2002, Yarie et al. 2007, Mack et al. 2008). Additional field data were also collected during two 2010 field campaigns at different locations in the Yukon Flats. Linear regressions have been developed based on field-based shrub and tree biomass and various lidar metrics of canopy height calculated for the plots (900 m^2). A multiple linear regression performed at the plot level resulted in a strong relationship (R^2=0.88) between observed and predicted biomass at the plot level. The coefficients for this regression were used to generate a shrub and tree biomass map for the entire Yukon Flats study area covered by lidar. This biomass map will be evaluated using additional field data collected in 2010 as well as other remote sensing data sources. Furthermore, additional lidar metrics (e.g. height of median energy) are being derived from the raw

  16. Preliminary Test for Constitutive Models of CAP

    Energy Technology Data Exchange (ETDEWEB)

    Choo, Yeon Joon; Hong, Soon Joon; Hwang, Su Hyun; Lee, Keo Hyung; Kim, Min Ki; Lee, Byung Chul [FNC Tech., Seoul (Korea, Republic of); Ha, Sang Jun; Choi, Hoon [Korea Electric Power Research Institute, Daejeon (Korea, Republic of)

    2010-05-15

    The development project for the domestic design code was launched to be used for the safety and performance analysis of pressurized light water reactors. As a part of this project, CAP (Containment Analysis Package) code has been developing for the containment safety and performance analysis side by side with SPACE. The CAP code treats three fields (vapor, continuous liquid and dispersed drop) for the assessment of containment specific phenomena, and is featured by assessment capabilities in multi-dimensional and lumped parameter thermal hydraulic cell. Thermal hydraulics solver was developed and has a significant progress now. Implementation of the well proven constitutive models and correlations are essential in other for a containment code to be used with the generalized or optimized purposes. Generally, constitutive equations are composed of interfacial and wall transport models and correlations. These equations are included in the source terms of the governing field equations. In order to develop the best model and correlation package of the CAP code, various models currently used in major containment analysis codes, such as GOTHIC, CONTAIN2.0 and CONTEMPT-LT are reviewed. Several models and correlations were incorporated for the preliminary test of CAP's performance and test results and future plans to improve the level of execution besides will be discussed in this paper

  17. Preliminary Test for Constitutive Models of CAP

    International Nuclear Information System (INIS)

    Choo, Yeon Joon; Hong, Soon Joon; Hwang, Su Hyun; Lee, Keo Hyung; Kim, Min Ki; Lee, Byung Chul; Ha, Sang Jun; Choi, Hoon

    2010-01-01

    The development project for the domestic design code was launched to be used for the safety and performance analysis of pressurized light water reactors. As a part of this project, CAP (Containment Analysis Package) code has been developing for the containment safety and performance analysis side by side with SPACE. The CAP code treats three fields (vapor, continuous liquid and dispersed drop) for the assessment of containment specific phenomena, and is featured by assessment capabilities in multi-dimensional and lumped parameter thermal hydraulic cell. Thermal hydraulics solver was developed and has a significant progress now. Implementation of the well proven constitutive models and correlations are essential in other for a containment code to be used with the generalized or optimized purposes. Generally, constitutive equations are composed of interfacial and wall transport models and correlations. These equations are included in the source terms of the governing field equations. In order to develop the best model and correlation package of the CAP code, various models currently used in major containment analysis codes, such as GOTHIC, CONTAIN2.0 and CONTEMPT-LT are reviewed. Several models and correlations were incorporated for the preliminary test of CAP's performance and test results and future plans to improve the level of execution besides will be discussed in this paper

  18. Shorea robusta: A sustainable biomass feedstock

    Directory of Open Access Journals (Sweden)

    Vishal Kumar Singh

    2016-09-01

    Full Text Available The biomass feedstock needs to be available in a manner that is sustainable as well as renewable. However, obtaining reliable and cost effective supplies of biomass feedstock produced in a sustainable manner can prove to be difficult. Traditional biomass, mainly in the form of fallen leaves, fuel wood or dried dung, has long been the renewable and sustainable energy source for cooking and heating. Present study accounts for the biomass of fallen leaves of Shorea robusta, also known as sal, sakhua or shala tree, in the campus of BIT Mesra (Ranchi. These leaves are being gathered and burnt rather than being sold commercially. They contain water to varying degrees which affects their energy content. Hence, measurement of moisture content is critical for its biomass assessment. The leaves were collected, weighed, oven dried at 100oC until constant weight, then dry sample was reweighed to calculate the moisture content that has been driven off. By subtraction of moisture content from the initial weight of leaves, biomass was calculated. Using Differential Scanning Calorimeter (DSC the heat content of the leaves was calculated and the elemental analysis of leaf was done by CHNSO elemental analyser. Further, total biomass and carbon content of Sal tree was calculated using allometric equations so as to make a comparison to the biomass stored in dried fallen leaves

  19. The adjustment of global and partial dry biomass models for Pinus pinaster in the North-East of Portugal

    OpenAIRE

    Lopes, Domingos; Almeida, L.R.; Castro, João Paulo; Aranha, José

    2005-01-01

    Ecosystems net primary production quantification can be done by means of allometric equations. Carbon sequestration studies also involve the quantification of growth dry biomass, knowing the carbon percentage of dry biomass. Fieldwork complexity to collect these kind of data are often limitative for obtaining these mathematical models. Allometric equations were adjusted to estimate dry biomass of individual Pinus pinaster trees, using data from 30 trees. Statisticals form the final equatio...

  20. Lignocellulosic biomass utilization toward biorefinery using meshophilic Clostridial species

    NARCIS (Netherlands)

    Tamaru, Yutaka; Lopez Contreras, A.M.

    2013-01-01

    Lignocellulosic biomass such as agricultural, industrial, and forestry residues as well as
    dedicated crops constitute renewable and abundant resources with great potential for a lowcost
    and uniquely sustainable bioconversion to value-added bioproducts. Thus, many
    organic fuels and

  1. Modeling natural regeneration biomass of Pinus stand

    Directory of Open Access Journals (Sweden)

    Rafael Cubas

    2016-09-01

    Full Text Available Reliable biomass data are very important in the evaluation of ecosystems, and help in understanding the contribution of forests in climate change. Variables that describe the size of the tree, like diameter and height are directly associated with biomass, which allows the use of regression models to estimate this element. Therefore, this study aimed to estimate by regression models, the biomass of different compartments of natural regeneration of trees of a Pinus taeda L. stand. The data were obtained through direct destructive method, using 100 randomly selected trees in the understory of a stand of Pinus taeda. We analyzed three arithmetical models, three logarithmic and two models developed by Stepwise process. Logarithmic equations developed by Stepwise procedure showed the best estimates of total and stems biomass. However, for needles and twigs compartments the best adjust was observed with Husch model and for root biomass Berkhout model proved to be the most suitable.

  2. Formulation and integration of constitutive models describing large deformations in thermoplasticity and thermoviscoplasticity

    International Nuclear Information System (INIS)

    Jansohn, W.

    1997-10-01

    This report deals with the formulation and numerical integration of constitutive models in the framework of finite deformation thermomechanics. Based on the concept of dual variables, plasticity and viscoplasticity models exhibiting nonlinear kinematic hardening as well as nonlinear isotropic hardening rules are presented. Care is taken that the evolution equations governing the hardening response fulfill the intrinsic dissipation inequality in every admissible process. In view of the development of an efficient numerical integration procedure, simplified versions of these constitutive models are supposed. In these versions, the thermoelastic strains are assumed to be small and a simplified kinematic hardening rule is considered. Additionally, in view of an implementation into the ABAQUS finite element code, the elasticity law is approximated by a hypoelasticity law. For the simplified onstitutive models, an implicit time-integration algorithm is developed. First, in order to obtain a numerical objective integration scheme, use is made of the HUGHES-WINGET-Algorithm. In the resulting system of ordinary differential equations, it can be distinguished between three differential operators representing different physical effects. The structure of this system of differential equations allows to apply an operator split scheme, which leads to an efficient integration scheme for the constitutive equations. By linearizing the integration algorithm the consistent tangent modulus is derived. In this way, the quadratic convergence of Newton's method used to solve the basic finite element equations (i.e. the finite element discretization of the governing thermomechanical field equations) is preserved. The resulting integration scheme is implemented as a user subroutine UMAT in ABAQUS. The properties of the applied algorithm are first examined by test calculations on a single element under tension-compression-loading. For demonstrating the capabilities of the constitutive theory

  3. Irreversible thermodynamics models and constitutive equations of the irradiation induced deformation and damage accumulating processes

    International Nuclear Information System (INIS)

    Wassilew, C.

    1989-11-01

    This report gives an overall evaluation of several in-reactor deformation and creep-rupture experiments performed in BR-2, FFTF, and Rapsodie on pressurised tubes of the stabilized austenitic stainless steels 1.4970, 1.4981, 1.4988, and the nickel base alloy Hastelloy-X. The irradiation induced deformation processes observed in the components operating in a neutron environment can be divided into two main groups: 1. volume conserving creep and 2. volumetric swelling. Since the observed deformation as well as damage accumulating phenomena are caused by the same constrained generated and free disposable point defects and helium atoms, it is obvious and advisable to analyze, and to model simultaneously the ensemble of the elementary mechanisms and processes effective at the same time. Phenomenological models based on the thermodynamics of irreversible processes have been developed, with the aim of: 1. grasping the partial relationships between the external variables and the response functions (creep, swelling, creep driven swelling, and time to rupture), 2. fathoming the rate-controlling mechanisms, 3. providing insight into the structural details and changes occurring during the deformation and the damage accumulating processes, 4. integrating the damage accumulating processes comprehensively, and 5. formulating the constitutive equations required to describe the elementary processes that generate plastic deformations as well as damage accumulation. (orig./MM)

  4. Computational fluid dynamics (CFD) modelling of coal/biomass co-firing in pulverised fuel boilers

    Energy Technology Data Exchange (ETDEWEB)

    Moghtaderi, B.; Meesri, C. [University of Newcastle, Callaghan, NSW (Australia). CRC for Coal in Sustainable Development, Dept. of Chemical Engineering

    2002-07-01

    The present study is concerned with computational fluid dynamics (CFD) modelling of coal/biomass blends co-fired under conditions pertinent to pulverised fuel (PF) boilers. The attention is particularly focused on the near burner zone to examine the impact of biomass on the flame geometry and temperature. The predictions are obtained by numerical solution of the conservation equations for the gas and particle phases. The gas phase is solved in the Eulerian domain using steady-state time-averaged Navier-Stokes equations while the solution of the particle phase is obtained from a series of Lagrangian particle tracking equations. Turbulence is modelled using the {kappa}-{epsilon} and Reynolds Stress models. The comparison between the predictions and experimental measurement reported in the literature resulted in a good agreement. Other influences of biomass co-firing are observed for fuel devolatilisation and burnout. 19 refs., 6 figs.

  5. Long-term multifactorial climate change impacts on mesofaunal biomass and nitrogen content

    DEFF Research Database (Denmark)

    Madsen, Mette Vestergård; Dyrnum, Kristine; Michelsen, Anders

    2015-01-01

    increased at elevated CO2, or tended do so. In contrast, enchytraeid N content decreased at elevated CO2. Soil microbial biomass N pool and litter C:N ratio also increased with elevated CO2, which suggests that mite biomasses are more coupled to microbial biomass, whereas enchytraeid biomass to a larger...... extent is governed by litter nitrogen concentration, i.e. litter quality. Structural equation modelling confirmed the positive coupling between soil microbial N content and oribatid biomass and further between oribatid and mesostigmatic biomass. The SEM also revealed a negative relationship between...... microbial N content and enchytraeid biomass. The biomass of all mesofaunal groups was reduced by spring drought, especially when combined with warming. Enchytraeid and especially collembolan biomass suffered greater drought declines than mite biomasses. We conclude that under long-term elevated CO2 exposure...

  6. Estimating leaf area and leaf biomass of open-grown deciduous urban trees

    Science.gov (United States)

    David J. Nowak

    1996-01-01

    Logarithmic regression equations were developed to predict leaf area and leaf biomass for open-grown deciduous urban trees based on stem diameter and crown parameters. Equations based on crown parameters produced more reliable estimates. The equations can be used to help quantify forest structure and functions, particularly in urbanizing and urban/suburban areas.

  7. Description of creep-plasticity interaction with non-unified constitutive equations: Application to an austenitic stainless steel

    International Nuclear Information System (INIS)

    Contesti, E.; Cailletaud, G.

    1989-01-01

    We present constitutive equations able to account for time independent plasticity together with creep and creep-plasticity interaction. A classical decomposition of the inelastic strain into a time independent plastic strain and a time dependent viscoplastic part is assumed. The coupling between both deformation modes (i.e. creep and plasticity) is obtained through an interaction between the plastic and viscoplastic state variables. In a first part, the capabilities of the model are described, and qualitative identifications are given in order to characterize the behaviour of the model. The practical applicability of the model is then tested, mainly using test results from the literature, but also specific data including creep, relaxation and tensile tests with various loading rates, as reported in the paper. The model is found able to discriminate between the increase of hardening produced by plasticity or creep. The effect of the loading rate on the subsequent amount of relaxation is correctly described and a good general agreement is observed between experiment and model predictions, even for complex loading paths (monotonic with temporary unloading periods, multiaxial loading paths in the stress space). (orig.)

  8. Anisotropic constitutive equation for use in finite difference wave propagation calculations. [Incorporation into TOODY code

    Energy Technology Data Exchange (ETDEWEB)

    Swegle, J.W.; Hicks, D.L.

    1979-05-01

    An anisotropic constitutive relation was incorporated into the Lagrangian finite-difference wavecode TOODY. The details of the implementation of the constitutive relation in the wavecode and an example of its use are discussed. 4 figures, 1 table.

  9. Timber volume and aboveground live tree biomass estimations for landscape analyses in the Pacific Northwest

    Science.gov (United States)

    Xiaoping Zhou; Miles A. Hemstrom

    2010-01-01

    Timber availability, aboveground tree biomass, and changes in aboveground carbon pools are important consequences of landscape management. There are several models available for calculating tree volume and aboveground tree biomass pools. This paper documents species-specific regional equations for tree volume and aboveground live tree biomass estimation that might be...

  10. Constitutive modeling for analysis and design of aluminum sheet forming processes

    International Nuclear Information System (INIS)

    Barlat, F.; Chung, K.; Yoon, J-W.; Choi, S-H.

    2000-01-01

    Finite element modeling (FEM) technology is one of the most powerful tools used to design new products, i.e. appliances, automotive, rigid packaging and aerospace parts, etc., and processes. However, FEM users need data and models to characterize the materials used to fabricate the new products. In fact, they need more information than the traditional and standard yield strength, ultimate strength, elongation, etc. Constitutive models and their associated coefficients represent a new way to describe material properties, a way that can be used by FEM users. In order to help manufacturers use more aluminum alloy sheet in their products, appropriate material models are needed to analyze and design specifically for these materials. This work describes a methodology that provides phenomenological constitutive equations based on three main microstructure components of aluminum alloys: dislocation density, second-phase particles and crystallographic texture. Examples of constitutive equations and their applications to numerical sheet forming process analysis and design are provided in this work. (author)

  11. Modeling of rock friction 1. Experimental results and constitutive equations

    International Nuclear Information System (INIS)

    Dieterich, J.H.

    1979-01-01

    Direct shear experiments on ground surfaces of a granodiorite from Raymond, California, at normal stresses of approx.6 MPa demonstrate that competing time, displacement, and velocity, effects control rock friction. It is proposed that the strength of the population of points of contacts between sliding surfaces determines frictional strength and that the population of contacts changes continuously with displacements. Previous experiments demonstrate that the strength of the contacts increases with the age of the contacts. The present experiments establish that a characteristic displacement, proportional to surface roughness, is required to change the population of contacts. Hence during slip the average age of the points of contact and therefore frictional strength decrease as slip velocity increases. Displacement weakening and consequently the potential for unstable slip occur whenever displacement reduces the average age of the contacts. In addition to this velocity dependency, which arises from displacement dependency and time dependency, the experiments also show a competing but transient increase in friction whenever slip velocity increases. Creep of the sliding surface at stresses below that for steady state slip also observed. Constitutive relationships are developed that permit quantitative simulation of the friction versus displacement data as a function of surface roughness and for different time and velocity histories. Unstable slip in experiments is controlled by these constitutive effects and by the stiffness of the experimental system. It is argued that analogous properties control earthquake instability

  12. Allometry and partitioning of above- and below-ground biomass in farmed eucalyptus species dominant in Western Kenyan agricultural landscapes

    International Nuclear Information System (INIS)

    Kuyah, Shem; Dietz, Johannes; Muthuri, Catherine; Noordwijk, Meine van; Neufeldt, Henry

    2013-01-01

    Farmers in developing countries are one of the world's largest and most efficient producers of sequestered carbon. However, measuring, monitoring and verifying how much carbon trees in smallholder farms are removing from the atmosphere has remained a great challenge in developing nations. Devising a reliable way for measuring carbon associated with trees in agricultural landscapes is essential for helping smallholder farmers benefit from emerging carbon markets. This study aimed to develop biomass equations specific to dominant eucalyptus species found in agricultural landscapes in Western Kenya. Allometric relationships were developed by regressing diameter at breast height (DBH) alone or DBH in combination with height, wood density or crown area against the biomass of 48 trees destructively sampled from a 100 km 2 site. DBH alone was a significant predictor variable and estimated aboveground biomass (AGB) with over 95% accuracy. The stems, branches and leaves formed up to 74, 22 and 4% of AGB, respectively, while belowground biomass (BGB) of the harvested trees accounted for 21% of the total tree biomass, yielding an overall root-to-shoot ratio (RS) of 0.27, which varied across tree size. Total tree biomass held in live Eucalyptus trees was estimated to be 24.4 ± 0.01 Mg ha −1 , equivalent to 11.7 ± 0.01 Mg of carbon per hectare. The equations presented provide useful tools for estimating tree carbon stocks of Eucalyptus in agricultural landscapes for bio-energy and carbon accounting. These equations can be applied to Eucalyptus in most agricultural systems with similar agro-ecological settings where tree growth parameters would fall within ranges comparable to the sampled population. -- Highlights: ► Equation with DBH alone estimated aboveground biomass with about 95% accuracy. ► Local generic equations overestimated above- and below-ground biomass by 10 and 48%. ► Height, wood density and crown area data did not improve model accuracy. ► Stems

  13. An empirical, integrated forest biomass monitoring system

    Science.gov (United States)

    Kennedy, Robert E.; Ohmann, Janet; Gregory, Matt; Roberts, Heather; Yang, Zhiqiang; Bell, David M.; Kane, Van; Hughes, M. Joseph; Cohen, Warren B.; Powell, Scott; Neeti, Neeti; Larrue, Tara; Hooper, Sam; Kane, Jonathan; Miller, David L.; Perkins, James; Braaten, Justin; Seidl, Rupert

    2018-02-01

    The fate of live forest biomass is largely controlled by growth and disturbance processes, both natural and anthropogenic. Thus, biomass monitoring strategies must characterize both the biomass of the forests at a given point in time and the dynamic processes that change it. Here, we describe and test an empirical monitoring system designed to meet those needs. Our system uses a mix of field data, statistical modeling, remotely-sensed time-series imagery, and small-footprint lidar data to build and evaluate maps of forest biomass. It ascribes biomass change to specific change agents, and attempts to capture the impact of uncertainty in methodology. We find that: • A common image framework for biomass estimation and for change detection allows for consistent comparison of both state and change processes controlling biomass dynamics. • Regional estimates of total biomass agree well with those from plot data alone. • The system tracks biomass densities up to 450-500 Mg ha-1 with little bias, but begins underestimating true biomass as densities increase further. • Scale considerations are important. Estimates at the 30 m grain size are noisy, but agreement at broad scales is good. Further investigation to determine the appropriate scales is underway. • Uncertainty from methodological choices is evident, but much smaller than uncertainty based on choice of allometric equation used to estimate biomass from tree data. • In this forest-dominated study area, growth and loss processes largely balance in most years, with loss processes dominated by human removal through harvest. In years with substantial fire activity, however, overall biomass loss greatly outpaces growth. Taken together, our methods represent a unique combination of elements foundational to an operational landscape-scale forest biomass monitoring program.

  14. The Riemannian geometry is not sufficient for the geometrization of the Maxwell's equations

    Science.gov (United States)

    Kulyabov, Dmitry S.; Korolkova, Anna V.; Velieva, Tatyana R.

    2018-04-01

    The transformation optics uses geometrized Maxwell's constitutive equations to solve the inverse problem of optics, namely to solve the problem of finding the parameters of the medium along the paths of propagation of the electromagnetic field. For the geometrization of Maxwell's constitutive equations, the quadratic Riemannian geometry is usually used. This is due to the use of the approaches of the general relativity. However, there arises the question of the insufficiency of the Riemannian structure for describing the constitutive tensor of the Maxwell's equations. The authors analyze the structure of the constitutive tensor and correlate it with the structure of the metric tensor of Riemannian geometry. It is concluded that the use of the quadratic metric for the geometrization of Maxwell's equations is insufficient, since the number of components of the metric tensor is less than the number of components of the constitutive tensor. A possible solution to this problem may be a transition to Finslerian geometry, in particular, the use of the Berwald-Moor metric to establish the structural correspondence between the field tensors of the electromagnetic field.

  15. On constitutive modelling and information for phenomenal distributed parameter control of multicomponent chemical processes in fluid- and solidphase

    International Nuclear Information System (INIS)

    Niemiec, W.

    1985-01-01

    The problem under consideration is to find common physicochemical conditions of kinetics and phenomena of multicomponent chemical processes in fluid- and solidphase, deciding yield and quality of final products of these processes. The paper is devoted to the construction of a fundamental distributed parameter constitutive theory of physicochemical modelling of these chemical processes treated from the view of isotropic and anisotropic nonhomogeneous media with space and time memories. On the basis of definition of derivative and constitutive equations of continuity, original system of partial differential constitutive state equations are deduced

  16. Solid biomass barometer - EurObserv'ER - November 2010

    International Nuclear Information System (INIS)

    2010-11-01

    solid biomass leaves the other renewable energy sources standing in terms of use and potential. Primary energy output from solid biomass combustion rose in 2009 yet again to a new height of 72.8 Mtoe, which equates to a 3.6% increase on 2008. The reason for this exploit, which prevailed over the tight economic context, is the resolve made by many countries to rely on this energy to achieve their European electricity or heat production target levels

  17. Solving differential equations with unknown constitutive relations as recurrent neural networks

    Energy Technology Data Exchange (ETDEWEB)

    Hagge, Tobias J.; Stinis, Panagiotis; Yeung, Enoch H.; Tartakovsky, Alexandre M.

    2017-12-08

    We solve a system of ordinary differential equations with an unknown functional form of a sink (reaction rate) term. We assume that the measurements (time series) of state variables are partially available, and use a recurrent neural network to “learn” the reaction rate from this data. This is achieved by including discretized ordinary differential equations as part of a recurrent neural network training problem. We extend TensorFlow’s recurrent neural network architecture to create a simple but scalable and effective solver for the unknown functions, and apply it to a fedbatch bioreactor simulation problem. Use of techniques from recent deep learning literature enables training of functions with behavior manifesting over thousands of time steps. Our networks are structurally similar to recurrent neural networks, but differ in purpose, and require modified training strategies.

  18. A Constitutive Model for Superelastic Shape Memory Alloys Considering the Influence of Strain Rate

    Directory of Open Access Journals (Sweden)

    Hui Qian

    2013-01-01

    Full Text Available Shape memory alloys (SMAs are a relatively new class of functional materials, exhibiting special thermomechanical behaviors, such as shape memory effect and superelasticity, which enable their applications in seismic engineering as energy dissipation devices. This paper investigates the properties of superelastic NiTi shape memory alloys, emphasizing the influence of strain rate on superelastic behavior under various strain amplitudes by cyclic tensile tests. A novel constitutive equation based on Graesser and Cozzarelli’s model is proposed to describe the strain-rate-dependent hysteretic behavior of superelastic SMAs at different strain levels. A stress variable including the influence of strain rate is introduced into Graesser and Cozzarelli’s model. To verify the effectiveness of the proposed constitutive equation, experiments on superelastic NiTi wires with different strain rates and strain levels are conducted. Numerical simulation results based on the proposed constitutive equation and experimental results are in good agreement. The findings in this paper will assist the future design of superelastic SMA-based energy dissipation devices for seismic protection of structures.

  19. Processing of plane strain compression test results for investigation of AISI-304 stainless steel constitutive behavior

    International Nuclear Information System (INIS)

    Aksenov, Sergey A.; Puzino, Yuriy A.; Bober, Stanislav A.; Kliber, Jiri

    2015-01-01

    The paper is oriented toward the determination of constitutive equation constants by the inverse analysis of plane strain compression test results. The interpretation of such results is complicated by the inhomogeneity of strain rate distribution in the specimen caused by rigid ends, the lateral spreading of a specimen friction and the variation of temperature during the test. The results of plane strain compression tests of AISI-304 stainless steel are presented and significant deviations of temperature are observed at higher strain rates. Finite element simulation was performed to estimate the inhomogeneity of strain rate within the specimen and evaluate the effect of friction on the test results. Constitutive equations of the material were obtained by inverse analysis minimizing the deviations between the measured load values and the ones predicted by numerical simulation. Keywords: PSCT, AISI-304, Gleeble, constitutive equations, hot forming, FEM, inverse analysis.

  20. Biomass equations for Brazilian semiarid caatinga plants Equações para estimar a biomassa de plantas da caatinga do semi-árido brasileiro

    Directory of Open Access Journals (Sweden)

    Everardo V.S.B. Sampaio

    2005-12-01

    Full Text Available Allometric equations to estimate total aboveground alive biomass (B or crown projection area (C of ten caatinga species based on plant height (H and/or stem diameter at ground level (DGL or at breast height (DBH were developed. Thirty plants of each species, covering the common range of stem diameters (3 to 50 cm, were measured (C, H, DGL, DBH, cut at the base, separated into parts, weighted and subsampled to determine dry biomass. Wood density (p of the stem and the largest branches was determined. B, C, H and p ranged from 1 to 500 kg, 0.2 to 112 m², 1.3 to 11.8 m, and 0.45 to 1.03 g cm-3. Biomass of all 10 species, separately or together (excluding one cactus species, could be estimated with high coefficients of determination (R² using the power equation (B = aDGLb and DGL, DBH, H or combinations of diameter, height and density. Improvement by multiplying H and/or p to DGL or DBH was small. The mixed-species equation based only on DBH (valid up to 30 cm had a = 0.173 and b = 2.295, similar to averages of these parameters found in the literature but slightly lower than most of those for humid tropical vegetation. Crown area was significantly related to diameter, height and biomass.Equações alométricas foram desenvolvidas para estimar a biomassa aérea viva (B e a área de projeção da copa (C de dez espécies da caatinga, com base na altura da planta (H e/ou do diâmetro do caule ao nível do solo (DNS ou à altura do peito (DAP. Trinta plantas de cada espécie, cobrindo a faixa usual de diâmetros (3 a 50 cm, foram medidas (C, H, DNS, DAP, cortadas na base, separadas em partes, pesadas e subamostradas para determinação da biomassa seca. A densidade (p da madeira dos caules e galhos maiores foi determinada. B, C, H e p variaram de 1 a 500 kg, 0,2 a 112 m², 1,3 a 11,8 m e 0,45 a 1,03 g cm-3. A biomassa das 10 espécies, separadamente ou em conjunto (exceto pela espécie de Cactaceae, foi estimada com alto coeficiente de determina

  1. Constitutive Modelling of Resins in the Compliance Domain

    Science.gov (United States)

    Klasztorny, M.

    2004-07-01

    A rheological HWKK/H model for resins is developed taking into consideration the up-to-date analyses of experimental results. Constitutive compliance equations of linear are formulated for this model in the shear/bulk form, which describes, among other things, the first-rank reversible isothermal creep. The shear (distorsional) deformations are simulated with three independent stress history functions of fractional and normal exponential types. The volume deformations are simulated as perfectly elastic. The model is described by two elastic and six viscoelastic constants, namely three long-term creep coefficients and three retardation times. The constitutive compliance equations of viscoealsticity for resins are also formulated in the coupled form. Formulae for converting the constants of shear/bulk (uncoupled) viscoelasticity into the constants of coupled viscoelasticity are given too. An algorithm for identifying the material constants, based on the creep of uniaxially tensioned bar samples, is formulated in a way that gives unique results. The material constants are fiund for Epidian 53 epoxy and Polimal 109 polyester resins. The creep processes, simulated based on the experimental data, are presented graphically for both the resins examined.

  2. Large Deformation Constitutive Laws for Isotropic Thermoelastic Materials

    Energy Technology Data Exchange (ETDEWEB)

    Plohr, Bradley J. [Los Alamos National Laboratory; Plohr, Jeeyeon N. [Los Alamos National Laboratory

    2012-07-25

    We examine the approximations made in using Hooke's law as a constitutive relation for an isotropic thermoelastic material subjected to large deformation by calculating the stress evolution equation from the free energy. For a general thermoelastic material, we employ the volume-preserving part of the deformation gradient to facilitate volumetric/shear strain decompositions of the free energy, its first derivatives (the Cauchy stress and entropy), and its second derivatives (the specific heat, Grueneisen tensor, and elasticity tensor). Specializing to isotropic materials, we calculate these constitutive quantities more explicitly. For deformations with limited shear strain, but possibly large changes in volume, we show that the differential equations for the stress components involve new terms in addition to the traditional Hooke's law terms. These new terms are of the same order in the shear strain as the objective derivative terms needed for frame indifference; unless the latter terms are negligible, the former cannot be neglected. We also demonstrate that accounting for the new terms requires that the deformation gradient be included as a field variable

  3. Constructing constitutive relationships for seismic and aseismic fault slip

    Science.gov (United States)

    Beeler, N.M.

    2009-01-01

    For the purpose of modeling natural fault slip, a useful result from an experimental fault mechanics study would be a physically-based constitutive relation that well characterizes all the relevant observations. This report describes an approach for constructing such equations. Where possible the construction intends to identify or, at least, attribute physical processes and contact scale physics to the observations such that the resulting relations can be extrapolated in conditions and scale between the laboratory and the Earth. The approach is developed as an alternative but is based on Ruina (1983) and is illustrated initially by constructing a couple of relations from that study. In addition, two example constitutive relationships are constructed; these describe laboratory observations not well-modeled by Ruina's equations: the unexpected shear-induced weakening of silica-rich rocks at high slip speed (Goldsby and Tullis, 2002) and fault strength in the brittle ductile transition zone (Shimamoto, 1986). The examples, provided as illustration, may also be useful for quantitative modeling.

  4. Emission of toxic air pollutants from biomass combustion

    International Nuclear Information System (INIS)

    Houck, J.E.; Barnett, S.G.; Roholt, R.B.; Rock, M.E.

    1991-01-01

    Combustion of biomass for power generation, home heating, process steam generation, and waste disposal constitutes a major source of air pollutants nationwide. Emissions from hog-fueled boilers, demolition wood-fired power plants, municipal waste incinerators, woodstoves, fireplaces, pellet stoves, agricultural burning, and forestry burning have been characterized for a variety of purposes. These have included risk assessment, permitting, emission inventory development, source profiling for receptor modeling, and control technology evaluations. From the results of the source characterization studies a compilation of emission factors for criteria and non-criteria pollutants are presented here. Key among these pollutants are polycyclic aromatic hydrocarbons, priority pollutant metals, carbon monoxide, sulfur dioxide, nitrous oxides, and PM 10 particles. The emission factors from the biomass combustion processes are compared and contrasted with other pollutant sources. In addition, sampling and analysis procedures most appropriate for characterizing emissions from the biomass combustion sources are also discussed

  5. Matching species and sites for biomass plantations in Hawaii

    International Nuclear Information System (INIS)

    Phillips, V.D.; Takahashi, P.K.; Singh, D.; Khan, M.A.

    1991-01-01

    Two methods for matching species and sites for biomass plantations in Hawaii were utilized to estimate biomass yields and production costs for Eucalyptus grandis, Eucalyptus saligna, and Leucaena leucocephala. The 'analogous site' method matches the environmental conditions, including soil, rainfall, temperature, and insolation parameters, of well-characterized experimental biomass research sites which produce known yields of these species with similar land areas, or with those areas that can be made similar through soil amendments and improvement, where no field trials exist. The result is the identification of sites with biomass growth, yield, and cost performances which are analogous to the experimental site. The 'regression model' method relates known site-specific biomass productivity with environmental and soil conditions and management practices developed from sites featuring widely different and distinct environmental conditions. Equations then enable the prediction of biomass performance and production costs for each species at any location statewide. The analytical results, using a geographical information system database and the above methods, are presented in map form to expedite the site selection process which indicates expected biomass yield and cost for several fast-growing tropical hardwood species in Hawaii

  6. Advancing individual tree biomass prediction: assessment and alternatives to the component ratio method

    Science.gov (United States)

    Aaron Weiskittel; Jereme Frank; David Walker; Phil Radtke; David Macfarlane; James Westfall

    2015-01-01

    Prediction of forest biomass and carbon is becoming important issues in the United States. However, estimating forest biomass and carbon is difficult and relies on empirically-derived regression equations. Based on recent findings from a national gap analysis and comprehensive assessment of the USDA Forest Service Forest Inventory and Analysis (USFS-FIA) component...

  7. A continuum mechanics constitutive framework for transverse isotropic soft tissues

    Science.gov (United States)

    Garcia-Gonzalez, D.; Jérusalem, A.; Garzon-Hernandez, S.; Zaera, R.; Arias, A.

    2018-03-01

    In this work, a continuum constitutive framework for the mechanical modelling of soft tissues that incorporates strain rate and temperature dependencies as well as the transverse isotropy arising from fibres embedded into a soft matrix is developed. The constitutive formulation is based on a Helmholtz free energy function decoupled into the contribution of a viscous-hyperelastic matrix and the contribution of fibres introducing dispersion dependent transverse isotropy. The proposed framework considers finite deformation kinematics, is thermodynamically consistent and allows for the particularisation of the energy potentials and flow equations of each constitutive branch. In this regard, the approach developed herein provides the basis on which specific constitutive models can be potentially formulated for a wide variety of soft tissues. To illustrate this versatility, the constitutive framework is particularised here for animal and human white matter and skin, for which constitutive models are provided. In both cases, different energy functions are considered: Neo-Hookean, Gent and Ogden. Finally, the ability of the approach at capturing the experimental behaviour of the two soft tissues is confirmed.

  8. Canada's forest biomass resources: deriving estimates from Canada's forest inventory

    International Nuclear Information System (INIS)

    Penner, M.; Power, K.; Muhairwe, C.; Tellier, R.; Wang, Y.

    1997-01-01

    A biomass inventory for Canada was undertaken to address the data needs of carbon budget modelers, specifically to provide estimates of above-ground tree components and of non-merchantable trees in Canadian forests. The objective was to produce a national method for converting volume estimates to biomass that was standardized, repeatable across the country, efficient and well documented. Different conversion methods were used for low productivity forests (productivity class 1) and higher productivity forests (productivity class 2). The conversion factors were computed by constructing hypothetical stands for each site, age, species and province combination, and estimating the merchantable volume and all the above-ground biomass components from suitable published equations. This report documents the procedures for deriving the national biomass inventory, and provides illustrative examples of the results. 46 refs., 9 tabs., 5 figs

  9. Biomass models to estimate carbon stocks for hardwood tree species

    Energy Technology Data Exchange (ETDEWEB)

    Ruiz-Peinado, R.; Montero, G.; Rio, M. del

    2012-11-01

    To estimate forest carbon pools from forest inventories it is necessary to have biomass models or biomass expansion factors. In this study, tree biomass models were developed for the main hardwood forest species in Spain: Alnus glutinosa, Castanea sativa, Ceratonia siliqua, Eucalyptus globulus, Fagus sylvatica, Fraxinus angustifolia, Olea europaea var. sylvestris, Populus x euramericana, Quercus canariensis, Quercus faginea, Quercus ilex, Quercus pyrenaica and Quercus suber. Different tree biomass components were considered: stem with bark, branches of different sizes, above and belowground biomass. For each species, a system of equations was fitted using seemingly unrelated regression, fulfilling the additivity property between biomass components. Diameter and total height were explored as independent variables. All models included tree diameter whereas for the majority of species, total height was only considered in the stem biomass models and in some of the branch models. The comparison of the new biomass models with previous models fitted separately for each tree component indicated an improvement in the accuracy of the models. A mean reduction of 20% in the root mean square error and a mean increase in the model efficiency of 7% in comparison with recently published models. So, the fitted models allow estimating more accurately the biomass stock in hardwood species from the Spanish National Forest Inventory data. (Author) 45 refs.

  10. Coupling and reduction of the HAWC equations

    DEFF Research Database (Denmark)

    Nim, E.

    2001-01-01

    This report contains a description of a general method for coupling and reduction of the so-called HAWC equations, which constitute the basis equations of motion of the aeroelastic model HAWC used widely by research institutes and industrial companies formore than the ten years. The principal aim....... In addition, the method enables the reduction of the number of degrees of freedom of the structure in order to increase the calculation efficiency and improve thecondition of the system.......This report contains a description of a general method for coupling and reduction of the so-called HAWC equations, which constitute the basis equations of motion of the aeroelastic model HAWC used widely by research institutes and industrial companies formore than the ten years. The principal aim...... of the work has been to enable the modelling wind turbines with large displacements of the blades in order to predict phenomena caused by geometric non-linear effects. However, the method can also be applied tomodel the nacelle/shaft structure of a turbine more detailed than the present HAWC model...

  11. A REVIEW ON BIOMASS DENSIFICATION TECHNOLOGIE FOR ENERGY APPLICATION

    Energy Technology Data Exchange (ETDEWEB)

    JAYA SHANKAR TUMULURU; CHRISTOPHER T. WRIGHT

    2010-08-01

    The world is currently facing challenges to reduce the dependence on fossil fuels and to achieve a sustainable renewable supply. Renewable energies represent a diversity of energy sources that can help to maintain the equilibrium of different ecosystems. Among the various sources of renewable energy, biomass is finding more uses as it is considered carbon neutral since the carbondioxide released during its use is already part of the carbon cycle (Arias et al., 2008). Increasing the utilization of biomass for energy can help to reduce the negative CO2 impact on the environment and help to meet the targets established in the Kyoto Protocol (UN, 1998). Energy from biomass can be produced from different processes like thermochemical (combustion, gasification, and pyrolysis), biological (anaerobic digestion, fermentation) or chemical (esterification) where direct combustion can provide a direct near-term energy solution (Arias et al., 2008). Some of the inherent problems with raw biomass materials, like low bulk density, high moisture content, hydrophilic nature and low calorific value, limit the ease of use of biomass for energy purposes (Arias et al., 2008). In fact, due to its low energy density compared to fossil fuels, high volumes of biomass will be needed; adding to problems associated with storage, transportation and feed handling at a cogeneration plant. Furthermore, grinding biomass pulverizes, can be very costly and in some cases impractical. All of these drawbacks have given rise to the development of new technologies in order to increase the quality of biomass fuels. The purpose of the work is mainly in four areas 1) Overview of the torrefaction process and to do a literature review on i) Physical properties of torrefied raw material and torrefaction gas composition. 2) Basic principles in design of packed bed i) Equations governing the flow of material in packed bed ii) Equations governing the flow of the gases in packed bed iii) Effect of physical

  12. BIOMASS IN Eucalyptus viminalis Labill. PLANTATIONS IN BUENOS AIRES PROVINCE, ARGENTINA

    Directory of Open Access Journals (Sweden)

    Paula Ferrere

    2009-10-01

    Full Text Available The present work was developed in the West of Buenos Aires Province (Argentina with the objective of adjusting functions of biomass of individual trees, in their different compartments and in the understorey. Stands of Eucalyptus viminalis Labill. were identified, with ages between 4 and 14 years-old. Twenty-one individuals were felled with diameters ranging from 9,2 to 32,5 cm. Simple and multiple regression models were developed and volume, branch leaf and stem biomass were estimated. The best volume equations were based on lineal models and the most adequate behavior was obtained with d2. To estimate leaf, branch and stem, ln-ln models have been suggested, with diameter and h or only diameter. The leaf biomass presented the weakest adjustment. The distribution of trees biomass agrees with the bibliography. The proportion of crown biomass decreases with age; on the other hand, the proportion of stem biomass increases with age.

  13. Lagrangian viscoelastic flow computations using the Rivlin-Sawyers constitutive model

    DEFF Research Database (Denmark)

    Rasmussen, Henrik Koblitz

    2000-01-01

    convected Maxwell fluid to a fluid described by an integral constitutive equation of the Rivlin-Sawyers type. This includes the K-BKZ model. The convergence of the method is demonstrated on the axisymmetric problem of the inflation of a polymeric membrane only restricted by a clamping ring....

  14. Impacts of Frequent Burning on Live Tree Carbon Biomass and Demography in Post-Harvest Regrowth Forest

    Directory of Open Access Journals (Sweden)

    Luke Collins

    2014-04-01

    Full Text Available The management of forest ecosystems to increase carbon storage is a global concern. Fire frequency has the potential to shift considerably in the future. These shifts may alter demographic processes and growth of tree species, and consequently carbon storage in forests. Examination of the sensitivity of forest carbon to the potential upper and lower extremes of fire frequency will provide crucial insight into the magnitude of possible change in carbon stocks associated with shifts in fire frequency. This study examines how tree biomass and demography of a eucalypt forest regenerating after harvest is affected by two experimentally manipulated extremes in fire frequency (i.e., ~3 year fire intervals vs. unburnt sustained over a 23 year period. The rate of post-harvest biomass recovery of overstorey tree species, which constituted ~90% of total living tree biomass, was lower within frequently burnt plots than unburnt plots, resulting in approximately 20% lower biomass in frequently burnt plots by the end of the study. Significant differences in carbon biomass between the two extremes in frequency were only evident after >15–20 years of sustained treatment. Reduced growth rates and survivorship of smaller trees on the frequently burnt plots compared to unburnt plots appeared to be driving these patterns. The biomass of understorey trees, which constituted ~10% of total living tree biomass, was not affected by frequent burning. These findings suggest that future shifts toward more frequent fire will potentially result in considerable reductions in carbon sequestration across temperate forest ecosystems in Australia.

  15. A constitutive law for dense granular flows.

    Science.gov (United States)

    Jop, Pierre; Forterre, Yoël; Pouliquen, Olivier

    2006-06-08

    A continuum description of granular flows would be of considerable help in predicting natural geophysical hazards or in designing industrial processes. However, the constitutive equations for dry granular flows, which govern how the material moves under shear, are still a matter of debate. One difficulty is that grains can behave like a solid (in a sand pile), a liquid (when poured from a silo) or a gas (when strongly agitated). For the two extreme regimes, constitutive equations have been proposed based on kinetic theory for collisional rapid flows, and soil mechanics for slow plastic flows. However, the intermediate dense regime, where the granular material flows like a liquid, still lacks a unified view and has motivated many studies over the past decade. The main characteristics of granular liquids are: a yield criterion (a critical shear stress below which flow is not possible) and a complex dependence on shear rate when flowing. In this sense, granular matter shares similarities with classical visco-plastic fluids such as Bingham fluids. Here we propose a new constitutive relation for dense granular flows, inspired by this analogy and recent numerical and experimental work. We then test our three-dimensional (3D) model through experiments on granular flows on a pile between rough sidewalls, in which a complex 3D flow pattern develops. We show that, without any fitting parameter, the model gives quantitative predictions for the flow shape and velocity profiles. Our results support the idea that a simple visco-plastic approach can quantitatively capture granular flow properties, and could serve as a basic tool for modelling more complex flows in geophysical or industrial applications.

  16. Viscoplastic behaviour including damage for deep argillaceous rocks: from in situ observations to constitutives equations

    International Nuclear Information System (INIS)

    Souley, Mountaka; Ghoreychi, Mehdi; Armand, Gilles

    2010-01-01

    viscoplastic model which aims to improve the viscoplastic strain prediction in the EDZ (Excavated Damaged Zone) is proposed by introducing damage variable in Lemaitre's model. The mains characteristics of the model are: (a) the short-term behaviour is based on a generalized Hoek-Brown model; (b) the long-term behaviour is based on the modified Lemaitre's model, the changes of viscoplastic strain rates due to damage (in pre peak phase) and failure (post-peak and residual phases) are taken into account by varying the creep activation energy and the strain-hardening as a function of the current damage rate. In addition, in order to prevent the overestimation of volumetric strain the associated flow rule initially assumed is revisited for the short term behaviour. The proposed model is implemented in FLAC3D C . In order to verify both constitutive equations and their implementations, several simulations of classical laboratory tests (uniaxial/triaxial, mono/multi stage creep and relaxation) are performed. As practical applications, the proposed model has been used to predict the behaviour of two galleries of the laboratory (at -490 m level): parallel and perpendicular to the major horizontal stress. Comparison between predicted results and the in situ measurements are then presented and discussed Finally the model limitations as well as possible improvements are discussed in this paper. (authors)

  17. Biomass estimation as a function of vertical forest structure and forest height: potential and limitations for radar remote sensing

    OpenAIRE

    Torano Caicoya, Astor; Kugler, Florian; Papathanassiou, Kostas; Biber, Peter; Pretzsch, Hans

    2010-01-01

    One common method to estimate biomass is measuring forest height and applying allometric equations to get forest biomass. Conditions like changing forest density or changing forest structure bias the allometric relations or biomass estimation fails completely. Remote sensing systems like SAR or LIDAR allow to measure vertical structure of forests. In this paper it is investigated whether vertical structure is sensitive to biomass. For this purpose vertical biomass profiles were calculated usi...

  18. Analysis of proteins involved in biodegradation of crop biomass

    Science.gov (United States)

    Crawford, Kamau; Trotman, Audrey

    1998-01-01

    The biodegradation of crop biomass for re-use in crop production is part of the bioregenerative life support concept proposed by the National Aeronautics and Space Administration (NASA) for long duration, manned space exploration. The current research was conducted in the laboratory to evaluate the use of electrophoretic analysis as a means of rapidly assaying for constitutive and induced proteins associated with the bacterial degradation of crop residue. The proteins involved in crop biomass biodegradation are either constitutive or induced. As a result, effluent and cultures were examined to investigate the potential of using electrophoretic techniques as a means of monitoring the biodegradation process. Protein concentration for optimum banding patterns was determined using the Bio-Rad Protein Assay kit. Four bacterial soil isolates were obtained from the G.W. Carver research Farm at Tuskegee University and used in the decomposition of components of plant biomass. The culture, WDSt3A was inoculated into 500 mL of either Tryptic Soy Broth or Nutrient Broth. Incubation, with shaking of each flask was for 96 hours at 30 C. The cultures consistently gave unique banding patterns under denaturing protein electrophoresis conditions, The associated extracellular enzymes also yielded characteristic banding patterns over a 14-day period, when native electrophoresis techniques were used to examine effluent from batch culture bioreactors. The current study evaluated sample preparation and staining protocols to determine the ease of use, reproducibility and reliability, as well as the potential for automation.

  19. Phasor Alternatives to Friis’ Transmission Equation

    DEFF Research Database (Denmark)

    Franek, Ondrej

    2018-01-01

    Two alternatives to Friis’ transmission equation in terms of phasor voltage waves are presented. In one formulation antennas are characterized by the complex effective length vectors. An additional form introducing field gain, that serves effectively as a phasor counterpart to the power gain......, is proposed. Both forms show the same degree of symmetry and modularity as the original Friis’ equation, but thanks to using phasors instead of power quantities they allow for superposition of fields or voltages. Although the new transmission equations are formulated in frequency domain, they also constitute...

  20. Constitutive relations for non-elastic deformation

    International Nuclear Information System (INIS)

    Hart, E.W.

    1978-01-01

    A new class of constitutive equations is described for non-elastic deformation of metals. The relations are embodied in a model that has had considerable experimental investigation. The model employs two deformation state variables of which one is a scalar hardness variable and the other is a stored anelastic strain. The description is entirely in terms of real time strain rates. The model and its experimental background is discussed. The relationship to mechanical calculations and a possible extension to radiation environment is also considered. (Auth.)

  1. Constitutional changes and the dilemmas of constitutionalism

    Directory of Open Access Journals (Sweden)

    Arsen Bačić

    2009-01-01

    Full Text Available The need to develop constitutional mechanisms whose aim is to resolve fundamental relations in society demands the widest possible inclusion of all of society’s active participants in the discussion on the need to adopt or revise the Constitution. The opening of every new round of constitutional changes is of great importance because it always unlocks certain new and important questions. The answers to those questions should be offered by state authority (policy and civil society including science and its disciplines. In this paper, the author mentions several topics which are of interest in the current discussion on the significance of current constitutional changes for the future of the development of constitutionalism and democracy in the Republic of Croatia. These are above all topics of political and legal constitutionalism and suggestions linked to strengthening the independence of judicial powers. The author advocates consistent application of constitutional control and check mechanisms which exclude all insularity of judicial powers in relation to democratic control.

  2. Relationships of Biomass with Environmental Factors in the Grassland Area of Hulunbuir, China

    Science.gov (United States)

    Liu, Miao; Liu, Guohua; Gong, Li; Wang, Dongbo; Sun, Jian

    2014-01-01

    Many studies have focused on the relationship between vegetation biomass and environmental factors in grassland. However, several questions remain to be answered, especially with regards to the spatial pattern of vegetation biomass. Thus, the distributed mechanism will be explored in the present study. Here, plant biomass was measured at 23 sites along a transect survey during the peak growing season in 2006. The data were analyzed with a classification and regression tree (CART) model. The structural equation modeling (SEM) was conducted to explicitly evaluate the both direct and indirect effects of these critical environmental elements on vegetation biomass. The results demonstrated that mean annual temperature (MAT) affected aboveground biomass (AGB) scored at −0.811 (Pbiomass (BGB) was −0.490 (Pbiomass distribution. PMID:25032808

  3. CFD simulation of gas and particles combustion in biomass furnaces

    Energy Technology Data Exchange (ETDEWEB)

    Griselin, Nicolas

    2000-11-01

    In this thesis, gas and particle combustion in biomass furnaces is investigated numerically. The aim of this thesis is to use Computational Fluid Dynamics (CFD) technology as an effective computer based simulation tool to study and develop the combustion processes in biomass furnaces. A detailed model for the numerical simulation of biomass combustion in a furnace, including fixed-bed modeling, gas-phase calculation (species distribution, temperature field, flow field) and gas-solid two-phase interaction for flying burning particles is presented. This model is used to understand the mechanisms of combustion and pollutant emissions under different conditions in small scale and large scale furnaces. The code used in the computations was developed at the Division of Fluid Mechanics, LTH. The flow field in the combustion enclosure is calculated by solving the Favre-averaged Navier-Stokes equations, with standard {kappa} - {epsilon} turbulence closure, together with the energy conservation equation and species transport equations. Discrete transfer method is used for calculating the radiation source term in the energy conservation equation. Finite difference is used to solve the general form of the equation yielding solutions for gas-phase temperatures, velocities, turbulence intensities and species concentrations. The code has been extended through this work in order to include two-phase flow simulation of particles and gas combustion. The Favre-averaged gas equations are solved in a Eulerian framework while the submodels for particle motion and combustion are used in the framework of a Lagrangian approach. Numerical simulations and measurement data of unburned hydrocarbons (UHC), CO, H{sub 2}, O{sub 2} and temperature on the top of the fixed bed are used to model the amount of tar and char formed during pyrolysis and combustion of biomass fuel in the bed. Different operating conditions are examined. Numerical calculations are compared with the measured data. It is

  4. A Prospect and Challenges for Adopting Constitutional Complaint and Constitutional Question in the Indonesian Constitutional Court

    OpenAIRE

    Faiz, Pan Mohamad

    2016-01-01

    A jurisdiction of the Indonesian Constitutional Court concerning constitutional adjudication is only limited to review the constitutionality of national law. There is no mechanism for challenging any decision or action made by public authorities that violate fundamental rights enshrined in the Indonesian Constitution. This article argues that constitutional complaint and constitutional question might be adopted as new jurisdictions of the Indonesian Constitutional Court in order to strengthen...

  5. [Simulation of three-dimensional green biomass of urban forests in Shenyang City and the factors affecting the biomass].

    Science.gov (United States)

    Liu, Chang-Fu; He, Xing-Yuan; Chen, Wei; Zhao, Gui-Ling; Xue, Wen-Duo

    2008-06-01

    Based on the fractal theory of forest growth, stepwise regression was employed to pursue a convenient and efficient method of measuring the three-dimensional green biomass (TGB) of urban forests in small area. A total of thirteen simulation equations of TGB of urban forests in Shenyang City were derived, with the factors affecting the TGB analyzed. The results showed that the coefficients of determination (R2) of the 13 simulation equations ranged from 0.612 to 0.842. No evident pattern was shown in residual analysis, and the precisions were all higher than 87% (alpha = 0.05) and 83% (alpha = 0.01). The most convenient simulation equation was ln Y = 7.468 + 0.926 lnx1, where Y was the simulated TGB and x1 was basal area at breast height per hectare (SDB). The correlations between the standard regression coefficients of the simulation equations and 16 tree characteristics suggested that SDB was the main factor affecting the TGB of urban forests in Shenyang.

  6. Application of symbolic computations to the constitutive modeling of structural materials

    Science.gov (United States)

    Arnold, Steven M.; Tan, H. Q.; Dong, X.

    1990-01-01

    In applications involving elevated temperatures, the derivation of mathematical expressions (constitutive equations) describing the material behavior can be quite time consuming, involved and error-prone. Therefore intelligent application of symbolic systems to faciliate this tedious process can be of significant benefit. Presented here is a problem oriented, self contained symbolic expert system, named SDICE, which is capable of efficiently deriving potential based constitutive models in analytical form. This package, running under DOE MACSYMA, has the following features: (1) potential differentiation (chain rule), (2) tensor computations (utilizing index notation) including both algebraic and calculus; (3) efficient solution of sparse systems of equations; (4) automatic expression substitution and simplification; (5) back substitution of invariant and tensorial relations; (6) the ability to form the Jacobian and Hessian matrix; and (7) a relational data base. Limited aspects of invariant theory were also incorporated into SDICE due to the utilization of potentials as a starting point and the desire for these potentials to be frame invariant (objective). The uniqueness of SDICE resides in its ability to manipulate expressions in a general yet pre-defined order and simplify expressions so as to limit expression growth. Results are displayed, when applicable, utilizing index notation. SDICE was designed to aid and complement the human constitutive model developer. A number of examples are utilized to illustrate the various features contained within SDICE. It is expected that this symbolic package can and will provide a significant incentive to the development of new constitutive theories.

  7. Estimation of the biomass of arbuscular mycorrhizal fungi in a linseed field

    DEFF Research Database (Denmark)

    Olsson, P.A.; Thingstrup, I.; Jakobsen, I.

    1999-01-01

    -organisms was estimated 28, 51 and 72 d after sowing based on amounts of certain fatty acids extracted from the soil. Dazomet application strongly suppressed colonisation of the linseed roots by AM fungi throughout the experiment. In plots with no dazomet application, root colonisation by the AM fungi increased from...... that the biomass of the extraradical mycelium of AM fungi was about 10 times as high as the biomass of intraradical mycelium and that the extraradical mycelium constituted the largest fraction of the soil microbial biomass. Dazomet application also decreased the biomass of saprophytic fungi in the soil...... harvests 1 to 3 as judged both from microscopical estimates and from quantitative analysis of the AM fungal indicative fatty acid 16.1 omega 5. These methods also revealed that AM formation was reduced in P-fertilised plots. The phospholipid fatty acid (PLFA) 16:1 omega 5 decreased in dazomet-treated soil...

  8. Non-integer viscoelastic constitutive law to model soft biological tissues to in-vivo indentation.

    Science.gov (United States)

    Demirci, Nagehan; Tönük, Ergin

    2014-01-01

    During the last decades, derivatives and integrals of non-integer orders are being more commonly used for the description of constitutive behavior of various viscoelastic materials including soft biological tissues. Compared to integer order constitutive relations, non-integer order viscoelastic material models of soft biological tissues are capable of capturing a wider range of viscoelastic behavior obtained from experiments. Although integer order models may yield comparably accurate results, non-integer order material models have less number of parameters to be identified in addition to description of an intermediate material that can monotonically and continuously be adjusted in between an ideal elastic solid and an ideal viscous fluid. In this work, starting with some preliminaries on non-integer (fractional) calculus, the "spring-pot", (intermediate mechanical element between a solid and a fluid), non-integer order three element (Zener) solid model, finally a user-defined large strain non-integer order viscoelastic constitutive model was constructed to be used in finite element simulations. Using the constitutive equation developed, by utilizing inverse finite element method and in vivo indentation experiments, soft tissue material identification was performed. The results indicate that material coefficients obtained from relaxation experiments, when optimized with creep experimental data could simulate relaxation, creep and cyclic loading and unloading experiments accurately. Non-integer calculus viscoelastic constitutive models, having physical interpretation and modeling experimental data accurately is a good alternative to classical phenomenological viscoelastic constitutive equations.

  9. Alloy design through mechanical equation of state

    International Nuclear Information System (INIS)

    Li, C.Yu.; Ellis, F.V.; Huang, F.H.

    1975-01-01

    The concept of plastic equation of state and the experimental results which are used to support this approach are introduced. It is shown that considerable savings in mechanical testing are possible in using this approach to establish the constitutive relationships for plastic deformation for a material. Advantages in data correlation and data extrapolation are also described. Examples are given to suggest that the constitutive relationships for plastic deformation obtained may be used as a useful basis for correlating the effects of composition and microstructure changes on mechanical properties and therefore serve as a guide for alloy selection. The savings in mechanical testing suggest also that the approach of plastic equation of state may be adopted for evaluating and assessing the mechanical properties of candidate alloys

  10. Extended Thermodynamics: a Theory of Symmetric Hyperbolic Field Equations

    Science.gov (United States)

    Müller, Ingo

    2008-12-01

    Extended thermodynamics is based on a set of equations of balance which are supplemented by local and instantaneous constitutive equations so that the field equations are quasi-linear first order differential equations. If the constitutive functions are subject to the requirements of the entropy principle, one may write them in symmetric hyperbolic form by a suitable choice of fields. The kinetic theory of gases, or the moment theories based on the Boltzmann equation provide an explicit example for extended thermodynamics. The theory proves its usefulness and practicality in the successful treatment of light scattering in rarefied gases. This presentation is based upon the book [1] of which the author of this paper is a co-author. For more details about the motivation and exploitation of the basic principles the interested reader is referred to that reference. It would seem that extended thermodynamics is worthy of the attention of mathematicians. It may offer them a non-trivial field of study concerning hyperbolic equations, if ever they get tired of the Burgers equation. Physicists may prefer to appreciate the success of extended thermodynamics in light scattering and to work on the open problems concerning the modification of the Navier-Stokes-Fourier theory in rarefied gases as predicted by extended thermodynamics of 13, 14, and more moments.

  11. Tree Biomass Allocation and Its Model Additivity for Casuarina equisetifolia in a Tropical Forest of Hainan Island, China

    Science.gov (United States)

    Xue, Yang; Yang, Zhongyang; Wang, Xiaoyan; Lin, Zhipan; Li, Dunxi; Su, Shaofeng

    2016-01-01

    Casuarina equisetifolia is commonly planted and used in the construction of coastal shelterbelt protection in Hainan Island. Thus, it is critical to accurately estimate the tree biomass of Casuarina equisetifolia L. for forest managers to evaluate the biomass stock in Hainan. The data for this work consisted of 72 trees, which were divided into three age groups: young forest, middle-aged forest, and mature forest. The proportion of biomass from the trunk significantly increased with age (Pbiomass of the branch and leaf decreased, and the biomass of the root did not change. To test whether the crown radius (CR) can improve biomass estimates of C. equisetifolia, we introduced CR into the biomass models. Here, six models were used to estimate the biomass of each component, including the trunk, the branch, the leaf, and the root. In each group, we selected one model among these six models for each component. The results showed that including the CR greatly improved the model performance and reduced the error, especially for the young and mature forests. In addition, to ensure biomass additivity, the selected equation for each component was fitted as a system of equations using seemingly unrelated regression (SUR). The SUR method not only gave efficient and accurate estimates but also achieved the logical additivity. The results in this study provide a robust estimation of tree biomass components and total biomass over three groups of C. equisetifolia. PMID:27002822

  12. Tree Biomass Allocation and Its Model Additivity for Casuarina equisetifolia in a Tropical Forest of Hainan Island, China.

    Science.gov (United States)

    Xue, Yang; Yang, Zhongyang; Wang, Xiaoyan; Lin, Zhipan; Li, Dunxi; Su, Shaofeng

    2016-01-01

    Casuarina equisetifolia is commonly planted and used in the construction of coastal shelterbelt protection in Hainan Island. Thus, it is critical to accurately estimate the tree biomass of Casuarina equisetifolia L. for forest managers to evaluate the biomass stock in Hainan. The data for this work consisted of 72 trees, which were divided into three age groups: young forest, middle-aged forest, and mature forest. The proportion of biomass from the trunk significantly increased with age (Pbiomass of the branch and leaf decreased, and the biomass of the root did not change. To test whether the crown radius (CR) can improve biomass estimates of C. equisetifolia, we introduced CR into the biomass models. Here, six models were used to estimate the biomass of each component, including the trunk, the branch, the leaf, and the root. In each group, we selected one model among these six models for each component. The results showed that including the CR greatly improved the model performance and reduced the error, especially for the young and mature forests. In addition, to ensure biomass additivity, the selected equation for each component was fitted as a system of equations using seemingly unrelated regression (SUR). The SUR method not only gave efficient and accurate estimates but also achieved the logical additivity. The results in this study provide a robust estimation of tree biomass components and total biomass over three groups of C. equisetifolia.

  13. Constitutive error based parameter estimation technique for plate structures using free vibration signatures

    Science.gov (United States)

    Guchhait, Shyamal; Banerjee, Biswanath

    2018-04-01

    In this paper, a variant of constitutive equation error based material parameter estimation procedure for linear elastic plates is developed from partially measured free vibration sig-natures. It has been reported in many research articles that the mode shape curvatures are much more sensitive compared to mode shape themselves to localize inhomogeneity. Complying with this idea, an identification procedure is framed as an optimization problem where the proposed cost function measures the error in constitutive relation due to incompatible curvature/strain and moment/stress fields. Unlike standard constitutive equation error based procedure wherein a solution of a couple system is unavoidable in each iteration, we generate these incompatible fields via two linear solves. A simple, yet effective, penalty based approach is followed to incorporate measured data. The penalization parameter not only helps in incorporating corrupted measurement data weakly but also acts as a regularizer against the ill-posedness of the inverse problem. Explicit linear update formulas are then developed for anisotropic linear elastic material. Numerical examples are provided to show the applicability of the proposed technique. Finally, an experimental validation is also provided.

  14. Constitutive basis of the MDCF model for rock salt

    International Nuclear Information System (INIS)

    Fossum, A.F.; Munson, D.E.; Chan, K.S.; Bodner, S.R.

    1996-01-01

    All valid constitutive equations must satisfy two general invariance principles as well several other principles. In this paper the MDCF (Multimechanism Deformation Coupled Fracture) model for rock salt is shown to be thermodynamically consistent, coordinate invariant, frame indifferent, and physically admissible. Additionally, the stress rates used in the formulation are shown to be kinematically consistent with the Cauchy stress rates

  15. Linear superposition solutions to nonlinear wave equations

    International Nuclear Information System (INIS)

    Liu Yu

    2012-01-01

    The solutions to a linear wave equation can satisfy the principle of superposition, i.e., the linear superposition of two or more known solutions is still a solution of the linear wave equation. We show in this article that many nonlinear wave equations possess exact traveling wave solutions involving hyperbolic, triangle, and exponential functions, and the suitable linear combinations of these known solutions can also constitute linear superposition solutions to some nonlinear wave equations with special structural characteristics. The linear superposition solutions to the generalized KdV equation K(2,2,1), the Oliver water wave equation, and the k(n, n) equation are given. The structure characteristic of the nonlinear wave equations having linear superposition solutions is analyzed, and the reason why the solutions with the forms of hyperbolic, triangle, and exponential functions can form the linear superposition solutions is also discussed

  16. An allometric equation for estimating stem biomass of Acacia ...

    African Journals Online (AJOL)

    Twelve different forms of linear, power and exponential equations were compared in this study to select the best model. Two models (VI and XI) were selected based on R 2, adjusted R 2, the Akaike information criterion, F-statistics and the five assumptions of linear regression. Model VI was discarded based on the ...

  17. Effects of model choice and forest structure on inventory-based estimations of Puerto Rican forest biomass

    Science.gov (United States)

    Thomas J. Brandeis; Maria Del Rocio; Suarez Rozo

    2005-01-01

    Total aboveground live tree biomass in Puerto Rican lower montane wet, subtropical wet, subtropical moist and subtropical dry forests was estimated using data from two forest inventories and published regression equations. Multiple potentially-applicable published biomass models existed for some forested life zones, and their estimates tended to diverge with increasing...

  18. Comparative study of different waste biomass for energy application.

    Science.gov (United States)

    Motghare, Kalyani A; Rathod, Ajit P; Wasewar, Kailas L; Labhsetwar, Nitin K

    2016-01-01

    Biomass is available in many varieties, consisting of crops as well as its residues from agriculture, forestry, and the agro-industry. These different biomass find their way as freely available fuel in rural areas but are also responsible for air pollution. Emissions from such solid fuel combustion to indoor, regional and global air pollution largely depend on fuel types, combustion device, fuel properties, fuel moisture, amount of air supply for combustion and also on climatic conditions. In both economic and environment point of view, gasification constitutes an attractive alternative for the use of biomass as a fuel, than the combustion process. A large number of studies have been reported on a variety of biomass and agriculture residues for their possible use as renewable fuels. Considering the area specific agriculture residues and biomass availability and related transportation cost, it is important to explore various local biomass for their suitability as a fuel. Maharashtra (India) is the mainstay for the agriculture and therefore, produces a significant amount of waste biomass. The aim of the present research work is to analyze different local biomass wastes for their proximate analysis and calorific value to assess their potential as fuel. The biomass explored include cotton waste, leaf, soybean waste, wheat straw, rice straw, coconut coir, forest residues, etc. mainly due to their abundance. The calorific value and the proximate analysis of the different components of the biomass helped in assessing its potential for utilization in different industries. It is observed that ash content of these biomass species is quite low, while the volatile matter content is high as compared to Indian Coal. This may be appropriate for briquetting and thus can be used as a domestic fuel in biomass based gasifier cook stoves. Utilizing these biomass species as fuel in improved cook-stove and domestic gasifier cook-stoves would be a perspective step in the rural energy and

  19. Biomass production in energy plantation of Prosopis juliflora

    Energy Technology Data Exchange (ETDEWEB)

    Gurumurti, K.

    1984-09-01

    Studies on time trends of biomass production by means of age series in energy plantations (spacing 1.3 x 1.3 m) of Prosopis juliflora is presented. The component biomass production at the age of 18, 24, 30, 36 and 48 months was determined. The results show considerable variation among the population of trees. However, distinct linear relationship between girth at breast height (GBH) and total height was discernible. The total biomass produced at 18, 24, 30, 36 and 48 months of age was 19.69, 41.39, 69.11, 114.62 and 148.63 dry tonnes per hectare, respectively. The corresponding figures for utilizable biomass (wood, bark and branch) were 14.63, 32.17, 50.59, 88.87 and 113.25 dry tonnes per hectare. At all the periods of study, branch component formed the major portion of total biomass being around 50 to 55%. Utilizable biomass was three-fourths of total biomass at all ages. The solar energy conversion efficiency ranged from 0.59% at 18 months to 1.68% at 48 months of age, the peak value being 1.87% at the age of 36 months. It is shown that the variables diameter and height can be used to reliably predict the biomass production in Prosopis juliflora with the help of the regression equations developed in the present study. It is concluded that Prosopis juliflora is an ideal candidate for energy plantations in semi arid and marginal lands, not only to meet the fuelwood demands but also to improve the soil fertility, for, this plant is a fast growing and nitrogen fixing leguminous tree.

  20. Evaluation of sampling strategies to estimate crown biomass

    Directory of Open Access Journals (Sweden)

    Krishna P Poudel

    2015-01-01

    Full Text Available Background Depending on tree and site characteristics crown biomass accounts for a significant portion of the total aboveground biomass in the tree. Crown biomass estimation is useful for different purposes including evaluating the economic feasibility of crown utilization for energy production or forest products, fuel load assessments and fire management strategies, and wildfire modeling. However, crown biomass is difficult to predict because of the variability within and among species and sites. Thus the allometric equations used for predicting crown biomass should be based on data collected with precise and unbiased sampling strategies. In this study, we evaluate the performance different sampling strategies to estimate crown biomass and to evaluate the effect of sample size in estimating crown biomass. Methods Using data collected from 20 destructively sampled trees, we evaluated 11 different sampling strategies using six evaluation statistics: bias, relative bias, root mean square error (RMSE, relative RMSE, amount of biomass sampled, and relative biomass sampled. We also evaluated the performance of the selected sampling strategies when different numbers of branches (3, 6, 9, and 12 are selected from each tree. Tree specific log linear model with branch diameter and branch length as covariates was used to obtain individual branch biomass. Results Compared to all other methods stratified sampling with probability proportional to size estimation technique produced better results when three or six branches per tree were sampled. However, the systematic sampling with ratio estimation technique was the best when at least nine branches per tree were sampled. Under the stratified sampling strategy, selecting unequal number of branches per stratum produced approximately similar results to simple random sampling, but it further decreased RMSE when information on branch diameter is used in the design and estimation phases. Conclusions Use of

  1. Thermal constitutive matrix applied to asynchronous electrical machine using the cell method

    Science.gov (United States)

    Domínguez, Pablo Ignacio González; Monzón-Verona, José Miguel; Rodríguez, Leopoldo Simón; Sánchez, Adrián de Pablo

    2018-03-01

    This work demonstrates the equivalence of two constitutive equations. One is used in Fourier's law of the heat conduction equation, the other in electric conduction equation; both are based on the numerical Cell Method, using the Finite Formulation (FF-CM). A 3-D pure heat conduction model is proposed. The temperatures are in steady state and there are no internal heat sources. The obtained results are compared with an equivalent model developed using the Finite Elements Method (FEM). The particular case of 2-D was also studied. The errors produced are not significant at less than 0.2%. The number of nodes is the number of the unknowns and equations to resolve. There is no significant gain in precision with increasing density of the mesh.

  2. Constitutive Model for Hot Deformation of the Cu-Zr-Ce Alloy

    Science.gov (United States)

    Zhang, Yi; Sun, Huili; Volinsky, Alex A.; Wang, Bingjie; Tian, Baohong; Liu, Yong; Song, Kexing

    2018-02-01

    Hot compressive deformation behavior of the Cu-Zr-Ce alloy has been investigated according to the hot deformation tests in the 550-900 °C temperature range and 0.001-10 s-1 strain rate range. Based on the true stress-true strain curves, the flow stress behavior of the Cu-Zr-Ce alloy was investigated. Microstructure evolution was observed by optical microscopy. Based on the experimental results, a constitutive equation, which reflects the relationships between the stress, strain, strain rate and temperature, has been established. Material constants n, α, Q and ln A were calculated as functions of strain. The equation predicting the flow stress combined with these materials constants has been proposed. The predicted stress is consistent with experimental stress, indicating that developed constitutive equation can adequately predict the flow stress of the Cu-Zr-Ce alloy. Dynamic recrystallization critical strain was determined using the work hardening rate method. According to the dynamic material model, the processing maps for the Cu-Zr and Cu-Zr-Ce alloy were obtained at 0.4 and 0.5 strain. Based on the processing maps and microstructure observations, the optimal processing parameters for the two alloys were determined, and it was found that the addition of Ce can promote the hot workability of the Cu-Zr alloy.

  3. Nonlinear electro-magneto-mechanical constitutive modelling of monolayer graphene

    Science.gov (United States)

    Sfyris, D.; Sfyris, G. I.; Bustamante, R.

    2016-04-01

    Using the classical theory of invariants for the specific class of graphene's symmetry, we constitutively characterize electro-magneto-mechanical interactions of graphene at continuum level. Graphene's energy depends on five arguments: the Finger strain tensor, the curvature tensor, the shift vector, the effective electric field intensity and the effective magnetic induction. The Finger strain tensor describes in- surface phenomena, the curvature tensor is responsible for the out-of-surface motions, while the shift vector is used due to the fact that graphene is a multilattice. The electric and the magnetic fields are described by the effective electric field intensity and the effective magnetic induction, respectively. An energy with the above arguments that also respects graphene's symmetries is found to have 42 invariants. Using these invariants, we evaluate all relevant measures by finding derivatives of the energy with respect to the five arguments of the energy. We also lay down the field equations that should be satisfied. These are the Maxwell equations, the momentum equation, the moment of momentum equation and the equation ruling the shift vector. Our framework is general enough to capture fully coupled processes in the finite deformation regime.

  4. The Role of Remote Sensing in Assessing Forest Biomass in Appalachian South Carolina

    Science.gov (United States)

    Shain, W.; Nix, L.

    1982-01-01

    Information is presented on the use of color infrared aerial photographs and ground sampling methods to quantify standing forest biomass in Appalachian South Carolina. Local tree biomass equations are given and subsequent evaluation of stand density and size classes using remote sensing methods is presented. Methods of terrain analysis, environmental hazard rating, and subsequent determination of accessibility of forest biomass are discussed. Computer-based statistical analyses are used to expand individual cover-type specific ground sample data to area-wide cover type inventory figures based on aerial photographic interpretation and area measurement. Forest biomass data are presented for the study area in terms of discriminant size classes, merchantability limits, accessibility (as related to terrain and yield/harvest constraints), and potential environmental impact of harvest.

  5. Constitutional judges (guarantee of the Constitution and responsibility

    Directory of Open Access Journals (Sweden)

    Francisco Javier Ansuátegui Roig

    2012-06-01

    Full Text Available My aim in this paper is to propose a reflection on the position and the importance that the constitutional judge has in the legal systems of contemporary constitutionalism. The figure of the judge responsible of protecting the Constitution is a key institution, without which we cannot understand the laws of constitutional democracies, their current lines of development, and the guarantee of rights and freedoms that constitute the normative core of these systems. Moreover, the reflection on the exercise of the powers of the judge, its scope and its justification is an important part of contemporary legal discussion, still relevant, albeit not exclusively - in the field of legal philosophy. The object of attention of my reflection is the judge who has the power of judicial review, in a scheme of defense of the Constitution, regardless the specific ways of this defense.

  6. A review of the challenges and opportunities in estimating above ground forest biomass using tree-level models

    Science.gov (United States)

    Hailemariam Temesgen; David Affleck; Krishna Poudel; Andrew Gray; John Sessions

    2015-01-01

    Accurate biomass measurements and analyses are critical components in quantifying carbon stocks and sequestration rates, assessing potential impacts due to climate change, locating bio-energy processing plants, and mapping and planning fuel treatments. To this end, biomass equations will remain a key component of future carbon measurements and estimation. As...

  7. Modeling loblolly pine aboveground live biomass in a mature pine-hardwood stand: a cautionary tale

    Science.gov (United States)

    D. C. Bragg

    2011-01-01

    Carbon sequestration in forests is a growing area of interest for researchers and land managers. Calculating the quantity of carbon stored in forest biomass seems to be a straightforward task, but it is highly dependent on the function(s) used to construct the stand. For instance, there are a number of possible equations to predict aboveground live biomass for loblolly...

  8. A mathematical model for the effects of volume fraction and fiber aspect ratio of biomass mixture during enzymatic hydrolysis

    Science.gov (United States)

    Jamil, Norazaliza Mohd; Wang, Qi

    2017-09-01

    Renewable energy or biofuel from lignocellulosic biomass is an alternative way to replace the depleting fossil fuels. The production cost can be reduced by increasing the concentration of biomass particles. However, lignocellulosic biomass is a suspension of natural fibres, and processing at high solid concentration is a challenging task. Thus, understanding the factors that affect the rheology of biomass suspension is crucial in order to maximize the production at a minimum cost. Our aim was to develop a mathematical model for enzymatic hydrolysis of cellulose by combining three scales: the macroscopic flow field, the mesoscopic particle orientation, and the microscopic reactive kinetics. The governing equations for the flow field, particle stress, kinetic equations, and particle orientation were coupled and were simultaneously solved using a finite element method based software, COMSOL. One of the main results was the changes in rheology of biomass suspension were not only due to the decrease in volume fraction of particles, but also due the types of fibres. The results from the simulation model agreed qualitatively with the experimental findings. This approach has enables us to obtain better predictive capabilities, hence increasing our understanding on the behaviour of biomass suspension.

  9. Biosorption of lanthanides using three kinds of seaweed biomasses

    International Nuclear Information System (INIS)

    Sakamoto, Nobuo; Wang, Yudan; Gao, Lidi; Kano, Naoki; Imaizumi, Hiroshi

    2010-01-01

    In order to evaluate the efficiency of seaweed biomass as sorbent for rare earth elements (REEs), sorption experiment from aqueous solutions containing known amount of lanthanide (La, Eu or Yb) using three kinds of Ca-loaded dried seaweeds (brown algae: Sargassum hemiphyllum, green algae: Ulva pertusa and red algae: Schizymenia dubyi) in single component system was explored. Furthermore, the sorption mechanism of these elements was investigated by applying Langmuir and Freundlich isotherm equations to the data obtained. In addition, to confirm the characteristics of the seaweed biomasses, the surface morphology of the biomass before and after metal adsorption was determined by Scanning Electron Microscope (SEM). Consequently, the following matters have been mainly clarified. (1) The morphology of Sargassum hemiphyllum and Ulva pertusa surface has hardly changed even after exposing to metals. On the other hand, the change of the surface condition on Schizymenia dubyi after adsorption was observed. (2) Adsorption isotherms using the seaweed biomass can be described by Langmuir and Freundlich isotherms satisfactorily for lanthanide. These adsorption may have occurred mainly by monolayer reaction because of better-fitting for Langmuir model. (3) The seaweed biomasses could be an efficient sorbent for REEs. Particularly, Ulva pertusa is found to be a promising biosorbent for removing La. (4) Ion-exchange process is considered to be the main mechanism responsible for the sorption of lanthanide ion onto the seaweed biomass. (author)

  10. Predicting the constitutive behavior of semi-solids via a direct finite element simulation: application to AA5182

    Science.gov (United States)

    Phillion, A. B.; Cockcroft, S. L.; Lee, P. D.

    2009-07-01

    The methodology of direct finite element (FE) simulation was used to predict the semi-solid constitutive behavior of an industrially important aluminum-magnesium alloy, AA5182. Model microstructures were generated that detail key features of the as-cast semi-solid: equiaxed-globular grains of random size and shape, interconnected liquid films, and pores at the triple-junctions. Based on the results of over fifty different simulations, a model-based constitutive relationship which includes the effects of the key microstructure features—fraction solid, grain size and fraction porosity—was derived using regression analysis. This novel constitutive equation was then validated via comparison with both the FE simulations and experimental stress/strain data. Such an equation can now be used to incorporate the effects of microstructure on the bulk semi-solid flow stress within a macro- scale process model.

  11. Predicting the constitutive behavior of semi-solids via a direct finite element simulation: application to AA5182

    International Nuclear Information System (INIS)

    Phillion, A B; Cockcroft, S L; Lee, P D

    2009-01-01

    The methodology of direct finite element (FE) simulation was used to predict the semi-solid constitutive behavior of an industrially important aluminum-magnesium alloy, AA5182. Model microstructures were generated that detail key features of the as-cast semi-solid: equiaxed-globular grains of random size and shape, interconnected liquid films, and pores at the triple-junctions. Based on the results of over fifty different simulations, a model-based constitutive relationship which includes the effects of the key microstructure features—fraction solid, grain size and fraction porosity—was derived using regression analysis. This novel constitutive equation was then validated via comparison with both the FE simulations and experimental stress/strain data. Such an equation can now be used to incorporate the effects of microstructure on the bulk semi-solid flow stress within a macro- scale process model

  12. Solution of Fokker–Planck equation by finite element and finite ...

    Indian Academy of Sciences (India)

    The response of a structural system to white noise excitation (delta-correlated) constitutes a Markov vector process whose transitional probability density function (TPDF) is governed by both the forward Fokker–Planck and backward Kolmogorov equations. Numerical solution of these equations by finite element and finite ...

  13. Generalized allometric regression to estimate biomass of Populus in short-rotation coppice

    Energy Technology Data Exchange (ETDEWEB)

    Ben Brahim, Mohammed; Gavaland, Andre; Cabanettes, Alain [INRA Centre de Toulouse, Castanet-Tolosane Cedex (France). Unite Agroforesterie et Foret Paysanne

    2000-07-01

    Data from four different stands were combined to establish a single generalized allometric equation to estimate above-ground biomass of individual Populus trees grown on short-rotation coppice. The generalized model was performed using diameter at breast height, the mean diameter and the mean height of each site as dependent variables and then compared with the stand-specific regressions using F-test. Results showed that this single regression estimates tree biomass well at each stand and does not introduce bias with increasing diameter.

  14. Modeling of global biomass policies

    International Nuclear Information System (INIS)

    Gielen, Dolf; Fujino, Junichi; Hashimoto, Seiji; Moriguchi, Yuichi

    2003-01-01

    This paper discusses the BEAP model and its use for the analysis of biomass policies for CO 2 emission reduction. The model considers competing land use, trade and leakage effects, and competing emission reduction strategies. Two policy scenarios are presented. In case of a 2040 time horizon the results suggest that a combination of afforestation and limited use of biomass for energy and materials constitutes the most attractive set of strategies. In case of a 'continued Kyoto' scenario including afforestation permit trade, the results suggest 5.1 Gt emission reduction based on land use change in 2020, two thirds of the total emission reduction by then. In case of global emission reduction, land use, land use change and forestry (LULUCF) accounts for one quarter of the emission reduction. However these results depend on the modeling time horizon. In case of a broader time horizon, maximized biomass production is more attractive than LULUCF. This result can be interpreted as a warning against a market based trading scheme for LULUCF credits. The model results suggest that the bioenergy market is dominated by transportation fuels and heating, and to a lesser extent feedstocks. Bioelectricity does not gain a significant market share in case competing CO 2 -free electricity options such as CO 2 capture and sequestration and nuclear are considered. To some extent trade in agricultural food products such as beef and cereals will be affected by CO 2 policies

  15. Modeling of global biomass policies

    International Nuclear Information System (INIS)

    Gielen, D.; Fujino, Junichi; Hashimoto, Seiji; Moriguchi, Yuichi

    2003-01-01

    This paper discusses the BEAP model and its use for the analysis of biomass policies for CO 2 emission reduction. The model considers competing land use, trade and leakage effects, and competing emission reduction strategies. Two policy scenarios are presented. In case of a 2040 time horizon the results suggest that a combination of afforestation and limited use of biomass for energy and materials constitutes the most attractive set of strategies. In case of a 'continued Kyoto' scenario including afforestation permit trade, the results suggest 5.1 Gt emission reduction based on land use change in 2020, two thirds of the total emission reduction by then. In case of global emission reduction, land use, land use change and forestry (LULUCF) accounts for one quarter of the emission reduction. However these results depend on the modeling time horizon. In case of a broader time horizon, maximized biomass production is more attractive than LULUCF. This result can be interpreted as a warning against a market based trading scheme for LULUCF credits. The model results suggest that the bioenergy market is dominated by transportation fuels and heating, and to a lesser extent feedstocks. Bioelectricity does not gain a significant market share in case competing CO 2 -free electricity options such as CO 2 capture and sequestration and nuclear are considered. To some extent trade in agricultural food products such as beef and cereals will be affected by CO 2 policies. (Author)

  16. Data-driven non-linear elasticity: constitutive manifold construction and problem discretization

    Science.gov (United States)

    Ibañez, Ruben; Borzacchiello, Domenico; Aguado, Jose Vicente; Abisset-Chavanne, Emmanuelle; Cueto, Elias; Ladeveze, Pierre; Chinesta, Francisco

    2017-11-01

    The use of constitutive equations calibrated from data has been implemented into standard numerical solvers for successfully addressing a variety problems encountered in simulation-based engineering sciences (SBES). However, the complexity remains constantly increasing due to the need of increasingly detailed models as well as the use of engineered materials. Data-Driven simulation constitutes a potential change of paradigm in SBES. Standard simulation in computational mechanics is based on the use of two very different types of equations. The first one, of axiomatic character, is related to balance laws (momentum, mass, energy,\\ldots ), whereas the second one consists of models that scientists have extracted from collected, either natural or synthetic, data. Data-driven (or data-intensive) simulation consists of directly linking experimental data to computers in order to perform numerical simulations. These simulations will employ laws, universally recognized as epistemic, while minimizing the need of explicit, often phenomenological, models. The main drawback of such an approach is the large amount of required data, some of them inaccessible from the nowadays testing facilities. Such difficulty can be circumvented in many cases, and in any case alleviated, by considering complex tests, collecting as many data as possible and then using a data-driven inverse approach in order to generate the whole constitutive manifold from few complex experimental tests, as discussed in the present work.

  17. National constitutional courts in the European Constitutional Democracy

    DEFF Research Database (Denmark)

    Komárek, Jan

    2014-01-01

    This article critically assesses the transformation of national constitutional courts’ place in the law and politics of the EU and its member states. This process eliminates the difference between constitutional and ordinary national courts, which is crucial for the institutional implementation...... of the discourse theory of law and democracy. It also disrupts the symbiotic relationship between national constitutional democracies established after World War II and European integration. The article argues that maintaining the special place of national constitutional courts is in the vital interest of both...... the EU and its member states, understood together as the European Constitutional Democracy—the central notion developed in this article in order to support an argument that should speak to both EU lawyers and national constitutionalists....

  18. From a tree to a stand in Finnish boreal forests - biomass estimation and comparison of methods

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Chunjiang

    2009-07-01

    There is an increasing need to compare the results obtained with different methods of estimation of tree biomass in order to reduce the uncertainty in the assessment of forest biomass carbon. In this study, tree biomass was investigated in a 30-year-old Scots pine (Pinus sylvestris) (Young-Stand) and a 130-year-old mixed Norway spruce (Picea abies)-Scots pine stand (Mature-Stand) located in southern Finland (61deg50' N, 24deg22' E). In particular, a comparison of the results of different estimation methods was conducted to assess the reliability and suitability of their applications. For the trees in Mature-Stand, annual stem biomass increment fluctuated following a sigmoid equation, and the fitting curves reached a maximum level (from about 1 kg yr-1 for understorey spruce to 7 kg yr-1 for dominant pine) when the trees were 100 years old). Tree biomass was estimated to be about 70 Mg ha-1 in Young-Stand and about 220 Mg ha-1 in Mature-Stand. In the region (58.00-62.13 degN, 14-34 degE, <= 300 m a.s.l.) surrounding the study stands, the tree biomass accumulation in Norway spruce and Scots pine stands followed a sigmoid equation with stand age, with a maximum of 230 Mg ha-1 at the age of 140 years. In Mature-Stand, lichen biomass on the trees was 1.63 Mg ha-1 with more than half of the biomass occurring on dead branches, and the standing crop of litter lichen on the ground was about 0.09 Mg ha-1. There were substantial differences among the results estimated by different methods in the stands. These results imply that a possible estimation error should be taken into account when calculating tree biomass in a stand with an indirect approach. (orig.)

  19. Method to determine the optimal constitutive model from spherical indentation tests

    Directory of Open Access Journals (Sweden)

    Tairui Zhang

    2018-03-01

    Full Text Available The limitation of current indentation theories was investigated and a method to determine the optimal constitutive model through spherical indentation tests was proposed. Two constitutive models, the Power-law and the Linear-law, were used in Finite Element (FE calculations, and then a set of indentation governing equations was established for each model. The load-depth data from the normal indentation depth was used to fit the best parameters in each constitutive model while the data from the further loading part was compared with those from FE calculations, and the model that better predicted the further deformation was considered the optimal one. Moreover, a Yang’s modulus calculation model which took the previous plastic deformation and the phenomenon of pile-up (or sink-in into consideration was also proposed to revise the original Sneddon-Pharr-Oliver model. The indentation results on six materials, 304, 321, SA508, SA533, 15CrMoR, and Fv520B, were compared with tensile ones, which validated the reliability of the revised E calculation model and the optimal constitutive model determination method in this study. Keywords: Optimal constitutive model, Spherical indentation test, Finite Element calculations, Yang’s modulus

  20. High Temperature Mechanical Constitutive Modeling of a High-Nb TiAl Alloy

    Directory of Open Access Journals (Sweden)

    DONG Chengli

    2018-02-01

    Full Text Available Uniaxial tensile, low cycle fatigue, fatigue-creep interaction and creep experiments of a novel high-Nb TiAl alloy (i.e. Ti-45Al-8Nb-0.2W-0.2B-0.02Y (atom fraction/% were conducted at 750℃ to obtain its tested data and curves. Based on Chaboche visco-plasticity unified constitutive model, Ohno-Wang modified non-linear kinematic hardening was introduced in Chaboche constitutive model to describe the cyclic hardening/softening, and Kachanov damage was coupled in Chaboche constitutive model to characterize the accelerated creep stage. The differential equations of the constitutive model discretized by explicit Euler method were compiled in to ABAQUS/UMAT to simulate the mechanical behavior of high-Nb TiAl alloy at different test conditions. The results show that Chaboche visco-plasticity unified constitutive model considering both Ohno-Wang modified non-linear kinematic hardening and Kachanov damage is able to simulate the uniaxial tensile, low cycle fatigue, fatigue-creep interaction and creep behavior of high-Nb TiAl alloy and has high accuracy.

  1. Biomass burning: A significant source of nutrients for Andean rainforests

    Science.gov (United States)

    Fabian, P. F.; Rollenbeck, R.; University Of Marburg, Germany

    2010-12-01

    Regular rain and fogwater sampling in the Podocarpus National Park,on the humid eastern slopes of the Ecuadorian Andes,has been carried out since 2002.The samples,accumulated over about 1-week intervals,were analysed for pH,conductivity,and major ions (K+, Na+, NH4+, Ca2+, Mg2+, Cl-, SO4 2-, NO3-, PO4 3- ).Annual deposition rates of these ions which, due to poor acidic soils with low mineralization rates,constitute the dominant nutrient supply to the mountaineous rainforests, and major ion sources could be determined using back trajectories,along with satellite data. While most of the Na, Cl, and K as well as Ca and Mg input was found to originate from natural oceanic and desert dust sources,respectively (P.Fabian et al.,Adv.Geosci.22,85-94, 2009), NO3, NH4, and about 90% of SO4 (about 10 % is from active volcanoes) are almost entirely due to anthropogenic sources,most likely biomass burning. Industrial and transportation emissions and other pollutants,however,act in a similar way as the precursors produced by biomass burning.For quantifying the impacts of biomass burning vs. those of anthropogenic sources other than biomass burning we used recently established emission inventories,along with simplified model calculations on back trajectories.First results yielding significant contributions of biomass burning will be discussed.

  2. Aboveground biomass equations for 7-year-old Acacia mangium Willd in Botucatu, Brazil

    Science.gov (United States)

    Ricardo A. A. Veiga; Maria A. M. Brasil; Carlos M. Carvalho

    2000-01-01

    The biomass of steins, leaves, and branches was determined for 152 sample trees of Acacia mangium Willd were in a 7-year-old experimental plantation in Botucatu, Sao Paulo State, Brazil. After felling, dimensional measurements were taken from each tree. Cross sections were collected in 125 sample trees at ground level (0 percent), 25 percent, 50...

  3. Method to determine the optimal constitutive model from spherical indentation tests

    Science.gov (United States)

    Zhang, Tairui; Wang, Shang; Wang, Weiqiang

    2018-03-01

    The limitation of current indentation theories was investigated and a method to determine the optimal constitutive model through spherical indentation tests was proposed. Two constitutive models, the Power-law and the Linear-law, were used in Finite Element (FE) calculations, and then a set of indentation governing equations was established for each model. The load-depth data from the normal indentation depth was used to fit the best parameters in each constitutive model while the data from the further loading part was compared with those from FE calculations, and the model that better predicted the further deformation was considered the optimal one. Moreover, a Yang's modulus calculation model which took the previous plastic deformation and the phenomenon of pile-up (or sink-in) into consideration was also proposed to revise the original Sneddon-Pharr-Oliver model. The indentation results on six materials, 304, 321, SA508, SA533, 15CrMoR, and Fv520B, were compared with tensile ones, which validated the reliability of the revised E calculation model and the optimal constitutive model determination method in this study.

  4. A better understanding of biomass co-firing by developing an advanced non-spherical particle tracking model

    DEFF Research Database (Denmark)

    Yin, Chungen; Rosendahl, Lasse Aistrup; Kær, Søren Knudsen

    2004-01-01

    -area-to-volume ratio and thus experiences a totally different motion and reaction as a non-spherical particle. Therefore, an advanced non-spherical particle-tracking model is developed to calculate the motion and reaction of nonspherical biomass particles. The biomass particles are assumed as solid or hollow cylinders......-gradient force. Since the drag and lift forces are both shape factor- and orientation-dependent, coupled particle rotation equations are resolved to update particle orientation. In the reaction of biomass particles, the actual particle surface area available and the average oxygen mass flux at particle surface...

  5. A micromorphic model for monolayer hexagonal boron nitride with determined constitutive constants by phonon dispersions

    International Nuclear Information System (INIS)

    Zhang, Bin; Yang, Gang

    2014-01-01

    A two dimensional (2D) micromorphic model is developed for monolayer hexagonal boron nitride (h-BN). Theoretical expressions of phonon dispersions for 2D crystals are derived based on the simplified governing equations of specialized three dimensional micromorphic crystals. The constitutive constants of governing equations of the h-BN micromorphic model are determined, which is performed by fitting the available phonon dispersions data of experimental measurements and first-principles calculations with our theoretical expressions. The obtained Young’s modulus and Poisson’s ratio of h-BN are comparable with the results of ab initio calculations and inelastic x-ray scattering experiments, thus the constitutive relations of the h-BN model are verified, which also indicates that mechanical properties of monolayer h-BN could be characterized by our 2D micromorphic model

  6. Spaceborne Applications of P Band Imaging Radars for Measuring Forest Biomass

    Science.gov (United States)

    Rignot, Eric J.; Zimmermann, Reiner; vanZyl, Jakob J.

    1995-01-01

    In three sites of boreal and temperate forests, P band HH, HV, and VV polarization data combined estimate total aboveground dry woody biomass within 12 to 27% of the values derived from allometric equations, depending on forest complexity. Biomass estimates derived from HV-polarization data only are 2 to 14% less accurate. When the radar operates at circular polarization, the errors exceed 100% over flooded forests, wet or damaged trees and sparse open tall forests because double-bounce reflections of the radar signals yield radar signatures similar to that of tall and massive forests. Circular polarizations, which minimize the effect of Faraday rotation in spaceborne applications, are therefore of limited use for measuring forest biomass. In the tropical rain forest of Manu, in Peru, where forest biomass ranges from 4 kg/sq m in young forest succession up to 50 kg/sq m in old, undisturbed floodplain stands, the P band horizontal and vertical polarization data combined separate biomass classes in good agreement with forest inventory estimates. The worldwide need for large scale, updated, biomass estimates, achieved with a uniformly applied method, justifies a more in-depth exploration of multi-polarization long wavelength imaging radar applications for tropical forests inventories.

  7. A CFD model for biomass fast pyrolysis in fluidized-bed reactors

    Science.gov (United States)

    Xue, Qingluan; Heindel, T. J.; Fox, R. O.

    2010-11-01

    A numerical study is conducted to evaluate the performance and optimal operating conditions of fluidized-bed reactors for fast pyrolysis of biomass to bio-oil. A comprehensive CFD model, coupling a pyrolysis kinetic model with a detailed hydrodynamics model, is developed. A lumped kinetic model is applied to describe the pyrolysis of biomass particles. Variable particle porosity is used to account for the evolution of particle physical properties. The kinetic scheme includes primary decomposition and secondary cracking of tar. Biomass is composed of reference components: cellulose, hemicellulose, and lignin. Products are categorized into groups: gaseous, tar vapor, and solid char. The particle kinetic processes and their interaction with the reactive gas phase are modeled with a multi-fluid model derived from the kinetic theory of granular flow. The gas, sand and biomass constitute three continuum phases coupled by the interphase source terms. The model is applied to investigate the effect of operating conditions on the tar yield in a fluidized-bed reactor. The influence of various parameters on tar yield, including operating temperature and others are investigated. Predicted optimal conditions for tar yield and scale-up of the reactor are discussed.

  8. Burnout of pulverized biomass particles in large scale boiler - Single particle model approach

    Energy Technology Data Exchange (ETDEWEB)

    Saastamoinen, Jaakko; Aho, Martti; Moilanen, Antero [VTT Technical Research Centre of Finland, Box 1603, 40101 Jyvaeskylae (Finland); Soerensen, Lasse Holst [ReaTech/ReAddit, Frederiksborgsveij 399, Niels Bohr, DK-4000 Roskilde (Denmark); Clausen, Soennik [Risoe National Laboratory, DK-4000 Roskilde (Denmark); Berg, Mogens [ENERGI E2 A/S, A.C. Meyers Vaenge 9, DK-2450 Copenhagen SV (Denmark)

    2010-05-15

    Burning of coal and biomass particles are studied and compared by measurements in an entrained flow reactor and by modelling. The results are applied to study the burning of pulverized biomass in a large scale utility boiler originally planned for coal. A simplified single particle approach, where the particle combustion model is coupled with one-dimensional equation of motion of the particle, is applied for the calculation of the burnout in the boiler. The particle size of biomass can be much larger than that of coal to reach complete burnout due to lower density and greater reactivity. The burner location and the trajectories of the particles might be optimised to maximise the residence time and burnout. (author)

  9. Hg(II) removal from aqueous solutions by bacillus subtilis biomass

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xue Song; Li, Fei Yan; He, Wen; Miao, Hua Hua [Department of Chemical Engineering, Huaihai Institute of Technology, Lianyungang (China)

    2010-01-15

    The biosorption of Hg(II) from aqueous solutions using Bacillus subtilis biomass was investigated in this study. The adsorbent was characterized by FTIR. Various factors including solution pH, initial concentration of Hg(II), contact time, reaction temperature and ionic strength were taken into account and promising results were obtained. An initial solution pH of 5.0 was most favorable for Hg(II) removal. The kinetic data was also analyzed using pseudo first order and pseudo second order equations. The results suggested that Hg(II) bioadsorption was best represented by the pseudo second order equation. Freundlich, Langmuir and Langmuir-Freundlich isotherms for the present systems were analyzed. The most satisfactory interpretation for the equilibrium data at different temperatures was given by the Langmuir-Freundlich isotherm. The effect of ionic strength on bioadsorption was significant. Bacillus subtilis biomass could serve as low cost adsorbent to remove Hg(II) from aqueous solutions, especially at lower concentrations of Hg(II) (<20 mg Hg/L). (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  10. 3D phenomenological constitutive modeling of shape memory alloys based on microplane theory

    International Nuclear Information System (INIS)

    Mehrabi, R; Kadkhodaei, M

    2013-01-01

    This paper concerns 3D phenomenological modeling of shape memory alloys using microplane theory. In the proposed approach, transformation is assumed to be the only source of inelastic strain in 1D constitutive laws considered for any generic plane passing through a material point. 3D constitutive equations are derived by generalizing the 1D equations using a homogenization technique. In the developed model, inelastic strain is explicitly stated in terms of the martensite volume fraction. To compare this approach with incremental constitutive models, such an available model is applied in its 1D integral form to the microplane formulation, and it is shown that both the approaches produce similar results for different uniaxial loadings. A nonproportional loading is then studied, and the results are compared with those obtained from an available model in which the inelastic strain is divided into two separate portions for transformation and reorientation. A good agreement is seen between the results of the two approaches, indicating the capability of the proposed microplane formulation in predicting reorientation phenomena in shape memory alloys. The results of the model are compared with available experimental results for a nonproportional loading path, and a good agreement is seen between the findings. (paper)

  11. Solving the dynamic rupture problem with different numerical approaches and constitutive laws

    Science.gov (United States)

    Bizzarri, A.; Cocco, M.; Andrews, D.J.; Boschi, Enzo

    2001-01-01

    We study the dynamic initiation, propagation and arrest of a 2-D in-plane shear rupture by solving the elastodynamic equation by using both a boundary integral equation method and a finite difference approach. For both methods we adopt different constitutive laws: a slip-weakening (SW) law, with constant weakening rate, and rate- and state-dependent friction laws (Dieterich-Ruina). Our numerical procedures allow the use of heterogeneous distributions of constitutive parameters along the fault for both formulations. We first compare the two solution methods with an SW law, emphasizing the required stability conditions to achieve a good resolution of the cohesive zone and to avoid artificial complexity in the solutions. Our modelling results show that the two methods provide very similar time histories of dynamic source parameters. We point out that, if a careful control of resolution and stability is performed, the two methods yield identical solutions. We have also compared the rupture evolution resulting from an SW and a rate- and state-dependent friction law. This comparison shows that despite the different constitutive formulations, a similar behaviour is simulated during the rupture propagation and arrest. We also observe a crack tip bifurcation and a jump in rupture velocity (approaching the P-wave speed) with the Dieterich-Ruina (DR) law. The rupture arrest at a barrier (high strength zone) and the barrier-healing mechanism are also reproduced by this law. However, this constitutive formulation allows the simulation of a more general and complex variety of rupture behaviours. By assuming different heterogeneous distributions of the initial constitutive parameters, we are able to model a barrier-healing as well as a self-healing process. This result suggests that if the heterogeneity of the constitutive parameters is taken into account, the different healing mechanisms can be simulated. We also study the nucleation phase duration Tn, defined as the time

  12. Floristic, structural, and allometric equations to estimate arboreal volume and biomass in a cerradão site

    Directory of Open Access Journals (Sweden)

    Eder Pereira Miguel

    2017-08-01

    Full Text Available This objective of this study was to characterize the floristic, structural, and ecological groups and to estimate the arboreal volume and biomass of a cerradão site in Palmas, Tocantins, Brazil. A forest inventory was conducted on 10.15 ha of the study area. Plots of 400-m2 were used for systematic sampling. All standing trees (dead or alive with a breast-height diameter (DHB greater than 5 cm were identified and measured. Floristic diversity and horizontal structure were assessed using the Shannon and importance value indices, respectively. Forest vertical structure was classified into three stratata and the tree species were categorized into ecological groups. Ninety tree volumes were rigorously cubed and weighed. Fresh- and dry biomass were sampled and estimated. Mathematical models were applied and adjusted to estimate tree volume and biomass. It was observed that the species Myrcia splendens and Emmotum nitens and the families Fabaceae and Chrysobalanaceae were dominant in our study site. The pioneer (613 individuals ha-1 and climax (530 individuals ha-1 tree species group predominated. The floristic diversity index was estimated as 3.35 nats ind- 1. The vertical structure analysis indicated fewer individuals in the superior stratum (13% compared to the medium (63% and inferior (24% stratum. The Schumacher and Hall model showed better results with regard to estimated forest production. Forest volume and biomass estimates were 126.71 m³ ha-1 and 61.67 Mg ha-1, respectively. The studied cerradão area had high floristic diversity and climax species predominated. Since this cerradão is in close proximity to the Amazon biome, its volume and biomass stocks were higher than those estimated for other cerradão and forest formations within the Cerrado biome.

  13. Rational approximations to solutions of linear differential equations.

    Science.gov (United States)

    Chudnovsky, D V; Chudnovsky, G V

    1983-08-01

    Rational approximations of Padé and Padé type to solutions of differential equations are considered. One of the main results is a theorem stating that a simultaneous approximation to arbitrary solutions of linear differential equations over C(x) cannot be "better" than trivial ones implied by the Dirichlet box principle. This constitutes, in particular, the solution in the linear case of Kolchin's problem that the "Roth's theorem" holds for arbitrary solutions of algebraic differential equations. Complete effective proofs for several valuations are presented based on the Wronskian methods and graded subrings of Picard-Vessiot extensions.

  14. Liquefaction of Saturated Soil and the Diffusion Equation

    Science.gov (United States)

    Sawicki, Andrzej; Sławińska, Justyna

    2015-06-01

    The paper deals with the diffusion equation for pore water pressures with the source term, which is widely promoted in the marine engineering literature. It is shown that such an equation cannot be derived in a consistent way from the mass balance and the Darcy law. The shortcomings of the artificial source term are pointed out, including inconsistencies with experimental data. It is concluded that liquefaction and the preceding process of pore pressure generation and the weakening of the soil skeleton should be described by constitutive equations within the well-known framework of applied mechanics. Relevant references are provided

  15. FITTING AND TESTING ALLOMETRIC EQUATIONS FOR MEXICO’S SINALOAN TROPICAL DRY TREES AND FOREST INVENTORY PLOTS

    Directory of Open Access Journals (Sweden)

    Jose de Jesus Navar Chaidez

    2016-05-01

    Full Text Available Aboveground tree biomass (bole, branches and foliage, M, plays a key role in the conventional and sustainable management of forest communities. The standard approach to assess tree or plot M is harvesting trees, developing and fitting allometric equations to trees or forest inventory plot data. In the absence of local tree allometry, it is usually recommended to fit off site allometric equations to evaluate tree or plot M. This research aims: (a to develop an updated on site allometric equation (b to fit available off site allometric equations to destructively harvested trees and (c to fit available allometric equations to plot M of Mexico’s Sinaloan tropical dry forests to understand sources of inherent tree and plot M variability. Results showed that: (a the improved on site allometric equation increases precision in contrast to the conventional biomass equation previously reported as well as to off site tree M equations, (b off site allometry projects tree and plot M deviates by close to one order of magnitude. Two tested and recommended approaches to increase tree and plot M precision when fitting off site equations are: (i to use all available tree allometric functions to come up with a mean equation or (ii to calibrate off site equations by fitting new, local parameters that can be calculated using statistical programs.These options would eventually increase tree and plot M precision in regional evaluations.

  16. Biomass, stem basic density and expansion factor functions for five exotic conifers grown in Denmark

    DEFF Research Database (Denmark)

    Nord-Larsen, Thomas; Nielsen, Anders Tærø

    2015-01-01

    Adequate allometric equations are needed for estimating carbon pools of fast growing tree species in relation to international reporting of CO2 emissions and for assessing their possible contribution to increasing forest biomass resources. We developed models for predicting biomass, stem basic...... decreased from 1.8–2.0 in small trees (dbh 25 cm), but differed among species. The overall model explained 86% of the variation and included quadratic mean diameter and dbh....

  17. Biomass District Energy Trigeneration Systems: Emissions Reduction and Financial Impact

    International Nuclear Information System (INIS)

    Rentizelas, A.; Tolis, A.; Tatsiopoulos, I.

    2009-01-01

    Biomass cogeneration is widely used for district heating applications in central and northern Europe. Biomass trigeneration on the other hand, constitutes an innovative renewable energy application. In this work, an approved United Nations Framework Convention on Climate Change baseline methodology has been extended to allow the examination of biomass trigeneration applications. The methodology is applied to a case study in Greece to investigate various environmental and financial aspects of this type of applications. The results suggest that trigeneration may lead to significant emissions reduction compared to using fossil fuels or even biomass cogeneration and electricity generation. The emissions reduction achieved may be materialized into a considerable revenue stream for the project, if traded through a trading mechanism such as the European Union Greenhouse Gas Emission Trading Scheme. A sensitivity analysis has been performed to compensate for the high volatility of the emission allowances' value and the immaturity of the EU Trading Scheme, which prevent a reliable estimation of the related revenue. The work concludes that emission allowances trading may develop into one of the major revenue streams of biomass trigeneration projects, significantly increasing their financial yield and attractiveness. The impact on the yield is significant even for low future values of emission allowances and could become the main income revenue source of such projects, if emission allowances increase their value substantially. The application of trigeneration for district energy proves to lead to increased environmental and financial benefits compared to the cogeneration or electricity generation cases

  18. Constitutive Modeling of the Flow Stress of GCr15 Continuous Casting Bloom in the Heavy Reduction Process

    Science.gov (United States)

    Ji, Cheng; Wang, Zilin; Wu, Chenhui; Zhu, Miaoyong

    2018-04-01

    According to the calculation results of a 3D thermomechanical-coupled finite-element (FE) model of GCr15 bearing steel bloom during a heavy reduction (HR) process, the variation ranges in the strain rate and strain under HR were described. In addition, the hot deformation behavior of the GCr15 bearing steel was studied over the temperature range from 1023 K to 1573 K (750 °C to 1300 °C) with strain rates of 0.001, 0.01, and 0.1 s-1 in single-pass thermosimulation compression experiments. To ensure the accuracy of the constitutive model, the temperature range was divided into two temperature intervals according to the fully austenitic temperature of GCr15 steel [1173 K (900 °C)]. Two sets of material parameters for the constitutive model were derived based on the true stress-strain curves of the two temperature intervals. A flow stress constitutive model was established using a revised Arrhenius-type constitutive equation, which considers the relationships among the material parameters and true strain. This equation describes dynamic softening during hot compression processes. Considering the effect of glide and climb on the deformation mechanism, the Arrhenius-type constitutive equation was modified by a physically based approach. This model is the most accurate over the temperatures ranging from 1173 K to 1573 K (900 °C to 1300 °C) under HR deformation conditions (ignoring the range from 1273 K to 1573 K (1000 °C to 1300 °C) with a strain rate of 0.1 s-1). To ensure the convergence of the FE calculation, an approximated method was used to estimate the flow stress at temperatures greater than 1573 K (1300 °C).

  19. Unified inelastic constitutive equations incorporating dynamic strain aging for Mod. 9Cr-1Mo steel

    International Nuclear Information System (INIS)

    Yaguchi, Masatsugu; Takahashi, Yukio

    1998-01-01

    A unified constitutive model considering dynamic strain aging effect was developed in order to describe inelastic deformation behavior of the Mod. 9Cr-1Mo steel precisely. The inelastic behavior of the steel was summarized as follows. A rate dependent deformation was observed above 500degC, and there was no rate dependency under 400degC. However, stress relaxation behavior was observed even at rate independent temperature region. Further, a stress after relaxation depended on prior loading strain rate, and it showed a higher value as the strain rate was slow. A feature of the proposed constitutive model was that an applied stress consists of three stress components: a back stress, an overstress and an aging stress which corresponds to dynamics strain aging and shows a negative strain rate dependency. The aging stress was measured by strain rate change tests, and it showed larger values as the strain rates were slow and the temperatures were low. The backstress and the overstress were measured by strain dip tests. The backstress was approximately rate independent under 400degC, however it showed rate dependency above 500degC. The overstress showed larger values as the strain rates were fast and the temperatures were high. The material constants were determined systematically based on the measured values of each internal variable. In order to evaluate the validity of the constitutive model, numerical simulations were done for various inelastic deformation behavior of Mod. 9Cr-1Mo steel. The simulations agreed with experimental results very well in all cases. (author)

  20. Constitutive modelling of stainless steels for cryogenic applications. Strain induced martensitic transformation

    CERN Document Server

    Garion, C

    2001-01-01

    The 300-series stainless steels are metastable austenitic alloys: martensitic transformation occurs at low temperatures and/or when plastic strain fields develop in the structures. The transformation influences the mechanical properties of the material. The present note aims at proposing a set of constitutive equations describing the plastic strain induced martensitic transformation in the stainless steels at cryogenic temperatures. The constitutive modelling shall create a bridge between the material sciences and the structural analysis. For the structures developing and accumulating plastic deformations at sub-zero temperatures, it is of primary importance to be able to predict the intensity of martensitic transformation and its effect on the material properties. In particular, the constitutive model has been applied to predict the behaviour of the components of the LHC interconnections, the so-called bellows expansion joints (the LHC mechanical compensation system).

  1. Biomass application for heating primary schools in Portugal

    International Nuclear Information System (INIS)

    Pires, A.; Cordeiro, M.

    2000-01-01

    The use of renewable energies for heating the schools, hospitals, public and agricultural buildings and even houses must constitute a principal option instead a second choice. The life quality of the people, in this case the students of primary schools, must be concern for all the people whose working in the energy subject. All the people must be aware that the life quality must be tried by the use of the renewable energies and in this case the biomass. This work pretends to be a good contribution for using of this type of energy. (Author)

  2. Potential constitutive models for salt: Survey of phenomenology, micromechanisms, and equations

    International Nuclear Information System (INIS)

    Senseny, P.E.; Hansen, F.D.

    1987-12-01

    Results are given of a literature survey performed to document the thermomechanical phenomena and micromechanical processes observed for salt over the ranges of stress and temperature of interest for a high-level nuclear repository. The elastic and thermal expansion behavior of salt can be readily modeled by the generalized Duhamel Neumann form of Hooke's law with temperature-dependent elastic constants and coefficient of thermal expansion. Inelastic deformation is primarily viscoplastic, but also has a brittle component. The observed phenomenological behavior of salt occurs because of micromechanical processes. To the extent that these processes have been studied, a summary of deformation mechanisms in natural salt is included in this report. Eight constitutive models that appear to be capable of modeling the viscoplastic deformation have been selected from the literature. Two models have been selected to model brittle deformation. Insufficient data are available to develop a model for failure. 92 refs., 39 figs., 6 tabs

  3. A Constitutional Coup! The Take-Down of the First President of the Republic of Kosovo

    Directory of Open Access Journals (Sweden)

    Korab R. Sejdiu

    2013-07-01

    This paper argues that the Court should have dismissed the claim of the MPs as inadmissible on procedural grounds, specifically that it was filed by the MPs after the time permitted by law and that the MPs never maintained the number of 30 members that were needed for the group to be an authorized party. Additionally, even on the merits, the Court failed to distinguish between the constitutional requirement to not exercise a party function, which the President in this case did not do, but rather simply held the position in a suspended mode. Moreover, even had the President’s holding of the position amounted to a violation of the Constitution, in no way did that equate to a serious constitutional violation. Still, the Court held contrary to the Constitution, applicable laws, and the available evidence before it and found that the President had seriously violated the Constitution.

  4. Scaling and constitutive relationships in downcomer modeling

    International Nuclear Information System (INIS)

    Daly, B.J.; Harlow, F.H.

    1978-12-01

    Constitutive relationships to describe mass and momentum exchange in multiphase flow in a pressurized water reactor downcomer are presented. Momentum exchange between the phases is described by the product of the flux of momentum available for exchange and the effective area for interaction. The exchange of mass through condensation is assumed to occur along a distinct condensation boundary separating steam at saturation temperature from water in which the temperature falls off roughly linearly with distance from the boundary. Because of the abundance of nucleation sites in a typical churning flow in a downcomer, we propose an equilibrium evaporation process that produces sufficient steam per unit time to keep the water perpetually cooled to the saturation temperature. The transport equations, constitutive models, and boundary conditions used in the K-TIF numerical method are nondimensionalized to obtain scaling relationships for two-phase flow in the downcomer. The results indicate that, subject to idealized thermodynamic and hydraulic constraints, exact mathematical scaling can be achieved. Experiments are proposed to isolate the effects of parameters that contribute to mass, momentum, and energy exchange between the phases

  5. Data derived from constitutive laws for description of shock wave propagation in concrete. Final report

    International Nuclear Information System (INIS)

    Eibl, J.; Ockert, J.

    1994-01-01

    Especially the need to design safe reactor containments, but also the necessity to protect facilities and human beings against impacts induced secondarily by explosions and detonations, demand simulations and design calculations of concrete under shock wave loading. The necessary computer codes are available, but the relevant constitutive laws for concrete with volumetric pressures up to more than 10000 MPa are lacking. Therefore shock wave tests have been carried out to develop such constitutive laws by loading concrete slabs with contact explosions. By the use of hot-molded carbon composition resistors shock waves propagating through the slab were measured. Pressures up to 13900 MPa were registered. Additionally shock wave velocities were determined from the different arrival times of the wave at the gages. By these two measured values and the conservation equations of mass and momentum the needed p-V relationship, the so called Hugoniot-Curve, was established up to 13900 MPa. Using the theory of Mie-Grueneisen and the so called P-α model the Hugoniot-Curve was extended to the equation of state for concrete. In a first step the deviatoric part of the constitutive law was attached from own static experiments considering the existing knowledge of strain rate effects since relevant dynamic tests under extreme loads are not available. With this constitutive law the analysis of the experiments then was backward verified in detail. (orig.) [de

  6. Biomass shock pretreatment

    Science.gov (United States)

    Holtzapple, Mark T.; Madison, Maxine Jones; Ramirez, Rocio Sierra; Deimund, Mark A.; Falls, Matthew; Dunkelman, John J.

    2014-07-01

    Methods and apparatus for treating biomass that may include introducing a biomass to a chamber; exposing the biomass in the chamber to a shock event to produce a shocked biomass; and transferring the shocked biomass from the chamber. In some aspects, the method may include pretreating the biomass with a chemical before introducing the biomass to the chamber and/or after transferring shocked biomass from the chamber.

  7. Compacting biomass waste materials for use as fuel

    Science.gov (United States)

    Zhang, Ou

    conducted in a stoke boiler. A separate burning test was also carried out by burning biomass logs alone in an outdoor hot-water furnace for heating a building. Based on a previous coal compaction study, the process of biomass compaction was studied numerically by use of a non-linear finite element code. A constitutive model with sufficient generality was adapted for biomass material to deal with pore contraction during compaction. A contact node algorithm was applied to implement the effect of mold wall friction into the finite element program. Numerical analyses were made to investigate the pressure distribution in a die normal to the axis of compaction, and to investigate the density distribution in a biomass log after compaction. The results of the analyses gave generally good agreement with theoretical analysis of coal log compaction, although assumptions had to be made about the variation in the elastic modulus of the material and the Poisson's ratio during the compaction cycle.

  8. Numerical implementation of constitutive material law for simulating the kinkband formation in fiber composites

    DEFF Research Database (Denmark)

    Veluri, Badrinath; Jensen, Henrik Myhre

    2011-01-01

    constitutive equations for the constituent materials is adopted to model the non-linear behavior of the unidirectional layered materials. This material law is implemented as UMAT user subroutine in ABAQUS/Standard to study kinkband formation. The methodology provides a procedure to investigate the kinkband...

  9. Dynamics of Understory Shrub Biomass in Six Young Plantations of Southern Subtropical China

    Directory of Open Access Journals (Sweden)

    Yuanqi Chen

    2017-11-01

    Full Text Available Understory shrubs are an important component of forest ecosystems and drive ecosystem processes, such as ecosystem carbon cycling. However, shrub biomass carbon stocks have rarely been reported, which limits our understanding of ecosystem C stock and cycling. In this study, we evaluated carbon accumulation of shrub species using allometric equations based on height and basal diameter in six subtropical plantations at the age of 1, 3, 4 and 6 years. The results showed that plantation type did not significantly affect the total biomass of shrubs, but it significantly affected the biomass of Rhodomyrtus tomentosa, Ilex asprella, Clerodendrum fortunatum and Baeckea frutescens. The biomass of dominant shrub species R. tomentosa, I. asprella, Gardenia jasminoides and Melastoma candidum increased with stand age, while the biomass of C. fortunatum and B. frutescens decreased. The inconsistent biomass-time patterns of different shrub species may be the primary reason for the altered total shrub biomass in each plantation. Consequently, we proposed that R. tomentosa, I. asprella, G. jasminoides and M. candidum could be preferable for understory carbon accumulation and should be maintained or planted because of their important functions in carbon accumulation and high economic values in the young plantations of southern subtropical China.

  10. Random cyclic constitutive models of 0Cr18Ni10Ti pipe steel

    International Nuclear Information System (INIS)

    Zhao Yongxiang; Yang Bing

    2004-01-01

    Experimental study is performed on the random cyclic constitutive relations of a new pipe stainless steel, 0Cr18Ni10Ti, by an incremental strain-controlled fatigue test. In the test, it is verified that the random cyclic constitutive relations, like the wide recognized random cyclic strain-life relations, is an intrinsic fatigue phenomenon of engineering materials. Extrapolating the previous work by Zhao et al, probability-based constitutive models are constructed, respectively, on the bases of Ramberg-Osgood equation and its modified form. Scattering regularity and amount of the test data are taken into account. The models consist of the survival probability-strain-life curves, the confidence strain-life curves, and the survival probability-confidence-strain-life curves. Availability and feasibility of the models have been indicated by analysis of the present test data

  11. Constitutive model and electroplastic analysis of structures under cyclic loading

    International Nuclear Information System (INIS)

    Wang, X.; Lei, Y; Du, Q.

    1989-01-01

    Many engineering structures in nuclear reactors, thermal power stations, chemical plants and aerospace vehicles are subjected to cyclic mechanic-thermal loading, which is the main cause of structural fatigue failure. Over the past twenty years, designers and researchers have paid great attention to the research on life prediction and elastoplastic analysis of structures under cyclic loading. One of the key problems in elastoplastic analysis is to construct a reasonable constitutive model for cyclic plasticity. In the paper, the constitutive equations are briefly outlined. Then, the model is implemented in a finite element code to predict the response of cyclic loaded structural components such as a double-edge-notched plate, a grooved bar and a nozzle in spherical shell. Numerical results are compared with those from other theories and experiments

  12. Assessing changes in biomass, productivity, and C and N stores following Juniperus virginiana forest expansion into tallgrass prairie

    Energy Technology Data Exchange (ETDEWEB)

    Norris, M. D.; Blair, J. M.; Johnson, L. C. [Kansas State Univ., Manhattan, KS (United States); McKane, R. B. [Environmental Protection Agency, Western Ecology Division, Corvallis, OR (United States)

    2001-11-01

    The objective of this study was to assess changes in plant productivity and above-ground plant biomass associated with red cedar forest expansion into areas formerly dominated by tallgrass prairie. Regionally appropriate allometric biomass regression equations were developed for the nondestructive estimation of red cedar biomass in eastern Kansas, followed by quantification of the carbon and nitrogen content of selected biomass components. The equations were applied, along with measurements of leaf litter production, to selected local stands of mature closed-canopy red cedars to estimate above-ground biomass, standing stocks of carbon and nitrogen and annual above-ground net primary productivity. Above-ground plant biomass for these red cedar-dominated sites ranged from 114,100 kg/ha for the youngest stand to 210,700 kg/ha for the oldest. Annual above-ground net primary productivity (ANPP) ranged from 7,250 to 10,440 kg/ha/yr for the oldest and younger red cedar stands respectively. The ANPP in comparable tallgrass prairie sites in this region averages 3,690 k/ha/yr, indicating a large increase in carbon uptake and above-ground storage as a result of the change from prairie to red cedar forests. Comparing these results with similar published data from other sites led to the conclusion that the widespread change from tallgrass to red cedars across the woodland-prairie ecotone has important consequences for regional carbon storage.37 refs., 3 tabs., 3 figs.

  13. The constitutive compatibility method for identification of material parameters based on full-field measurements

    KAUST Repository

    Moussawi, Ali

    2013-10-01

    We revisit here the concept of the constitutive relation error for the identification of elastic material parameters based on image correlation. An additional concept, so called constitutive compatibility of stress, is introduced defining a subspace of the classical space of statically admissible stresses. The key idea is to define stresses as compatible with the observed deformation field through the chosen class of constitutive equation. This makes possible the uncoupling of the identification of stress from the identification of the material parameters. As a result, the global cost of the identification is strongly reduced. This uncoupling also leads to parametrized solutions in cases where the solution is non-unique as demonstrated on 2D numerical examples. © 2013 Elsevier B.V.

  14. Estimation of above ground biomass by using multispectral data for Evergreen Forest in Phu Hin Rong Kla National Park, Thailand

    International Nuclear Information System (INIS)

    Suwanprasit, C.

    2010-01-01

    Tropical forest is the most important and largest source for stocking CO 2 from the atmosphere which might be one of the main sources of carbon emission, global warming and climate change in recent decades. There are two main objectives of this study. The first one is to establish a relationship between above ground biomass and vegetation indices and the other is to evaluate above ground biomass and carbon sequestration for evergreen forest areas in Phu Hin Rong Kla National park, Thailand. Random sampling design based was applied for calculating the above ground biomass at stand level in the selected area by using Brown and Tsutsumi allometric equations. Landsat 7 ETM+ data in February 2009 was used. Support Vector Machine (SVM) was applied for identifying evergreen forest area. Forty-three of vegetation indices and image transformations were used for finding the best correlation with forest stand biomass. Regression analysis was used to investigate the relationship between the biomass volume at stand level and digital data from the satellite image. TM51 which derived from Tsutsumi allometric equation was the highest correlation with stand biomass. Normalized Difference Vegetation Index (NDVI) was not the best correlation in this study. The best biomass estimation model was from TM51 and ND71 (R2 =0.658). The totals of above ground biomass and carbon sequestration were 112,062,010 ton and 56,031,005 ton respectively. The application of this study would be quite useful for understanding the terrestrial carbon dynamics and global climate change. (author)

  15. Improving LiDAR Biomass Model Uncertainty through Non-Destructive Allometry and Plot-level 3D Reconstruction with Terrestrial Laser Scanning

    Science.gov (United States)

    Stovall, A. E.; Shugart, H. H., Jr.

    2017-12-01

    Future NASA and ESA satellite missions plan to better quantify global carbon through detailed observations of forest structure, but ultimately rely on uncertain ground measurement approaches for calibration and validation. A significant amount of the uncertainty in estimating plot-level biomass can be attributed to inadequate and unrepresentative allometric relationships used to convert plot-level tree measurements to estimates of aboveground biomass. These allometric equations are known to have high errors and biases, particularly in carbon rich forests because they were calibrated with small and often biased samples of destructively harvested trees. To overcome this issue, a non-destructive methodology for estimating tree and plot-level biomass has been proposed through the use of Terrestrial Laser Scanning (TLS). We investigated the potential for using TLS as a ground validation approach in LiDAR-based biomass mapping though virtual plot-level tree volume reconstruction and biomass estimation. Plot-level biomass estimates were compared on the Virginia-based Smithsonian Conservation Biology Institute's SIGEO forest with full 3D reconstruction, TLS allometry, and Jenkins et al. (2003) allometry. On average, full 3D reconstruction ultimately provided the lowest uncertainty estimate of plot-level biomass (9.6%), followed by TLS allometry (16.9%) and the national equations (20.2%). TLS offered modest improvements to the airborne LiDAR empirical models, reducing RMSE from 16.2% to 14%. Our findings suggest TLS plot acquisitions and non-destructive allometry can play a vital role for reducing uncertainty in calibration and validation data for biomass mapping in the upcoming NASA and ESA missions.

  16. Hydrogen from catalytic reforming of biomass-derived hydrocarbons in liquid water

    Science.gov (United States)

    Cortright, R. D.; Davda, R. R.; Dumesic, J. A.

    2002-08-01

    Concerns about the depletion of fossil fuel reserves and the pollution caused by continuously increasing energy demands make hydrogen an attractive alternative energy source. Hydrogen is currently derived from nonrenewable natural gas and petroleum, but could in principle be generated from renewable resources such as biomass or water. However, efficient hydrogen production from water remains difficult and technologies for generating hydrogen from biomass, such as enzymatic decomposition of sugars, steam-reforming of bio-oils and gasification, suffer from low hydrogen production rates and/or complex processing requirements. Here we demonstrate that hydrogen can be produced from sugars and alcohols at temperatures near 500K in a single-reactor aqueous-phase reforming process using a platinum-based catalyst. We are able to convert glucose-which makes up the major energy reserves in plants and animals-to hydrogen and gaseous alkanes, with hydrogen constituting 50% of the products. We find that the selectivity for hydrogen production increases when we use molecules that are more reduced than sugars, with ethylene glycol and methanol being almost completely converted into hydrogen and carbon dioxide. These findings suggest that catalytic aqueous-phase reforming might prove useful for the generation of hydrogen-rich fuel gas from carbohydrates extracted from renewable biomass and biomass waste streams.

  17. The Spatial Distribution of Forest Biomass in the Brazilian Amazon: A Comparison of Estimates

    Science.gov (United States)

    Houghton, R. A.; Lawrence, J. L.; Hackler, J. L.; Brown, S.

    2001-01-01

    The amount of carbon released to the atmosphere as a result of deforestation is determined, in part, by the amount of carbon held in the biomass of the forests converted to other uses. Uncertainty in forest biomass is responsible for much of the uncertainty in current estimates of the flux of carbon from land-use change. We compared several estimates of forest biomass for the Brazilian Amazon, based on spatial interpolations of direct measurements, relationships to climatic variables, and remote sensing data. We asked three questions. First, do the methods yield similar estimates? Second, do they yield similar spatial patterns of distribution of biomass? And, third, what factors need most attention if we are to predict more accurately the distribution of forest biomass over large areas? Amazonian forests (including dead and below-ground biomass) vary by more than a factor of two, from a low of 39 PgC to a high of 93 PgC. Furthermore, the estimates disagree as to the regions of high and low biomass. The lack of agreement among estimates confirms the need for reliable determination of aboveground biomass over large areas. Potential methods include direct measurement of biomass through forest inventories with improved allometric regression equations, dynamic modeling of forest recovery following observed stand-replacing disturbances (the approach used in this research), and estimation of aboveground biomass from airborne or satellite-based instruments sensitive to the vertical structure plant canopies.

  18. Minimizing bias in biomass allometry: Model selection and log transformation of data

    Science.gov (United States)

    Joseph Mascaro; undefined undefined; Flint Hughes; Amanda Uowolo; Stefan A. Schnitzer

    2011-01-01

    Nonlinear regression is increasingly used to develop allometric equations for forest biomass estimation (i.e., as opposed to the raditional approach of log-transformation followed by linear regression). Most statistical software packages, however, assume additive errors by default, violating a key assumption of allometric theory and possibly producing spurious models....

  19. Multi-decade biomass dynamics in an old-growth hemlock-northern hardwood forest, Michigan, USA

    Directory of Open Access Journals (Sweden)

    Kerry D. Woods

    2014-09-01

    Full Text Available Trends in living aboveground biomass and inputs to the pool of coarse woody debris (CWD in an undisturbed, old-growth hemlock-northern hardwood forest in northern MI were estimated from multi-decade observations of permanent plots. Growth and demographic data from seven plot censuses over 47 years (1962–2009, combined with one-time measurement of CWD pools, help assess biomass/carbon status of this landscape. Are trends consistent with traditional notions of late-successional forests as equilibrial ecosystems? Specifically, do biomass pools and CWD inputs show consistent long-term trends and relationships, and can living and dead biomass pools and trends be related to forest composition and history? Aboveground living biomass densities, estimated using standard allometric relationships, range from 360–450 Mg/ha among sampled stands and types; these values are among the highest recorded for northeastern North American forests. Biomass densities showed significant decade-scale variation, but no consistent trends over the full study period (one stand, originating following an 1830 fire, showed an aggrading trend during the first 25 years of the study. Even though total above-ground biomass pools are neither increasing nor decreasing, they have been increasingly dominated, over the full study period, by very large (>70 cm dbh stems and by the most shade-tolerant species (Acer saccharum and Tsuga canadensis.CWD pools measured in 2007 averaged 151 m3/ha, with highest values in Acer-dominated stands. Snag densities averaged 27/ha, but varied nearly ten-fold with canopy composition (highest in Tsuga-dominated stands, lowest in Acer-dominated; snags constituted 10–50% of CWD biomass. Annualized CWD inputs from tree mortality over the full study period averaged 1.9–3.2 Mg/ha/yr, depending on stand and species composition. CWD input rates tended to increase over the course of the study. Input rates may be expected to increase over longer

  20. In-depth investigation of enzymatic hydrolysis of biomass wastes based on three major components: Cellulose, hemicellulose and lignin.

    Science.gov (United States)

    Lin, Lili; Yan, Rong; Liu, Yongqiang; Jiang, Wenju

    2010-11-01

    The artificial biomass based on three biomass components (cellulose, hemicellulose and lignin) were developed on the basis of a simplex-lattice approach. Together with a natural biomass sample, they were employed in enzymatic hydrolysis researches. Different enzyme combines of two commercial enzymes (ACCELLERASE 1500 and OPTIMASH BG) showed a potential to hydrolyze hemicellulose completely. Negligible interactions among the three components were observed, and the used enzyme ACCELLERASE 1500 was proven to be weak lignin-binding. On this basis, a multiple linear-regression equation was established for predicting the reducing sugar yield based on the component proportions in a biomass. The hemicellulose and cellulose in a biomass sample were found to have different contributions in staged hydrolysis at different time periods. Furthermore, the hydrolysis of rice straw was conducted to validate the computation approach through considerations of alkaline solution pretreatment and combined enzymes function, so as to understand better the nature of biomass hydrolysis, from the aspect of three biomass components.

  1. Aboveground and belowground biomass allocation in native Prosopis caldenia Burkart secondaries woodlands in the semi-arid Argentinean pampas

    International Nuclear Information System (INIS)

    Risio, Lucia; Herrero, Celia; Bogino, Stella M.; Bravo, Felipe

    2014-01-01

    The woodlands in the south-west of the Argentinean pampas are dominated by Prosopis Caldenia Burkart (calden). The current deforestation rate of this woodlands is 0.82% per year. Different compensation initiatives have begun that recognize the role of forests as environmental service providers. The financial incentives they offer make it necessary to quantify the amount of carbon stored in the forest biomass. A model for estimating calden biomass was developed. Thirty-eight trees were selected, felled and divided into sections. An equation system was fitted using joint generalized regression to ensure the additivity property. A weighted regression was used to avoid heteroscedasticity. In these woodlands fire is the main disturbance and it can modify tree allometry, due this all models included the area of the base of the stem and tree height as independent variables since it indirectly collects this variability. Total biomass and the stem fraction had the highest R2 A dj. values (0.75), while branches with a diameter less than 7 cm had the lowest (0.58). Tree biomass was also analyzed by partitioning into the basic fractions of stem, crown, roots, and the root/shoot ratio. Biomass allocation was greatest in the crown fraction and the mean root/shoot ratio was 0.58. The carbon stock of the caldenales considering only calden tree biomass is 20.2 Mg ha −1 . While the overall carbon balance of the region is negative (deforestation and biomass burning, the remnant forested area has increased their calden density and in an indirect way his carbon sequestration capacity could also be increased. - Highlights: • A model for estimating aboveground and belowground Prosopis caldenia biomass was developed. • Biomass allocation into the tree and the root/shoot ratio were analyzed. • The equation systems presented had made it possible to more accurately estimate the biomass stored in calden woodlands

  2. Biomass torrefaction: A promising pretreatment technology for biomass utilization

    Science.gov (United States)

    Chen, ZhiWen; Wang, Mingfeng; Ren, Yongzhi; Jiang, Enchen; Jiang, Yang; Li, Weizhen

    2018-02-01

    Torrefaction is an emerging technology also called mild pyrolysis, which has been explored for the pretreatment of biomass to make the biomass more favorable for further utilization. Dry torrefaction (DT) is a pretreatment of biomass in the absence of oxygen under atmospheric pressure and in a temperature range of 200-300 degrees C, while wet torrrefaction (WT) is a method in hydrothermal or hot and high pressure water at the tempertures within 180-260 degrees C. Torrrefied biomass is hydrophobic, with lower moisture contents, increased energy density and higher heating value, which are more comparable to the characteristics of coal. With the improvement in the properties, torrefied biomass mainly has three potential applications: combustion or co-firing, pelletization and gasification. Generally, the torrefaction technology can accelerate the development of biomass utilization technology and finally realize the maximum applications of biomass energy.

  3. New Allometric Equations to Support Sustainable Plantation Management of Rosewood (Aniba rosaeodora Ducke in the Central Amazon

    Directory of Open Access Journals (Sweden)

    Pedro Krainovic

    2017-09-01

    Full Text Available Rosewood (Aniba rosaeodora Ducke is an endangered Amazonian tree species which produces one of the most valuable essential oils in the world. The species is used in silvicultural systems which are seen as a means to reducing the pressure of exploitation of natural rosewood populations. There are no specific equations for rosewood plantations, and therefore generalized equations are inappropriate for the species in commercial systems. This study presents allometric equations from 144 trees sampled in different rosewood plantations of Central Amazonia. The equations generated were compared with an equation used in forest management to estimate wood volume and another one recommended by law for rosewood biomass. The equation suggested by current legislation underestimates the actual values by more than 70% making the viable use of this equation impossible in commercial plantations. The equations generated to estimate the volume and biomass serve as an alternative to the need to develop specific equations for each area and age of the plant. The generic equation for the species is consistent for fresh mass management, with a generalized R2 of 0.80 and an underestimation of 0.33%. The equation for crown fresh mass estimation presented a generalized R2 of 0.32 and an underestimation of 0.24%. The underestimation of the mass production by rosewood plantations represents a serious impediment to this forest activity. The allometric equations developed are highly applicable under different conditions and management options and should be suggested by the legal provisions regulating rosewood-related activity in Central Amazonia.

  4. The comparative constitutional law on national constitutional system: with regard to the IX World Congress of Constitutional Law

    OpenAIRE

    Landa Arroyo, César

    2015-01-01

    From  the  process  of  globalization  of  law,  the  comparative constitutional law has gained a leading role for a better understanding and solving old and new constitutional national and international challenges. Therefore, some assumptions and considerations to take into account are presented for the development of the national constitutional order within the framework of the comparative constitutional law, such as universality and relativism of human rights; the concept of power and cons...

  5. Generalized heat-transport equations: parabolic and hyperbolic models

    Science.gov (United States)

    Rogolino, Patrizia; Kovács, Robert; Ván, Peter; Cimmelli, Vito Antonio

    2018-03-01

    We derive two different generalized heat-transport equations: the most general one, of the first order in time and second order in space, encompasses some well-known heat equations and describes the hyperbolic regime in the absence of nonlocal effects. Another, less general, of the second order in time and fourth order in space, is able to describe hyperbolic heat conduction also in the presence of nonlocal effects. We investigate the thermodynamic compatibility of both models by applying some generalizations of the classical Liu and Coleman-Noll procedures. In both cases, constitutive equations for the entropy and for the entropy flux are obtained. For the second model, we consider a heat-transport equation which includes nonlocal terms and study the resulting set of balance laws, proving that the corresponding thermal perturbations propagate with finite speed.

  6. Equations for transient flow-boiling in a duct

    International Nuclear Information System (INIS)

    Mathers, W.G.; Ferch, R.L.; Hancox, W.T.; McDonald, B.H.

    1981-01-01

    In this paper we derive a separated phase model for weakly coupled flows which extends a model presented elsewhere (BANERJEE, FERCH, MATHERS and McDONALD, 1978). A hyperbolic system of seven partial differential equations results with ensemble-averaged phase velocities, enthalpies and pressures, and void fraction as dependent variables (UVUTUP model). The required constitutive equations for mass, momentum and energy transfer between phases and between the phases and the boundaries are discussed. The relationship of the UVUTUP model to other existing models is also presented

  7. Renewable energy--traditional biomass vs. modern biomass

    International Nuclear Information System (INIS)

    Goldemberg, Jose; Teixeira Coelho, Suani

    2004-01-01

    Renewable energy is basic to reduce poverty and to allow sustainable development. However, the concept of renewable energy must be carefully established, particularly in the case of biomass. This paper analyses the sustainability of biomass, comparing the so-called 'traditional' and 'modern' biomass, and discusses the need for statistical information, which will allow the elaboration of scenarios relevant to renewable energy targets in the world

  8. Structural equations for Killing tensors of order two. II

    International Nuclear Information System (INIS)

    Hauser, I.; Malhiot, R.J.

    1975-01-01

    In a preceding paper, a new form of the structural equations for any Killing tensor of order two have been derived; these equations constitute a system analogous to the Killing vector equations Nabla/sub alpha/ K/sub beta/ = ω/sub alpha beta/ = -ω/sub beta alpha/ and Nabla/sub gamma/ ω/sub alpha beta = R/sub alpha beta gamma delta/ K/sup delta/. The first integrability condition for the Killing tensor structural equations is now derived. The structural equations and the integrability condition have forms which can readily be expressed in terms of a null tetrad to furnish a Killing tensor parallel of the Newman--Penrose equations; this is briefly described. The integrability condition implies the new result, for any given space--time, that the dimension of the set of second-order Killing tensors attains its maximum possible value of 50 only if the space--time is of constant curvature. Potential applications of the structural equations are discussed

  9. UNDERSTANDING INFORMAL CONSTITUTIONAL CHANGE

    Directory of Open Access Journals (Sweden)

    Stephen M. Griffin

    2016-01-01

    Full Text Available Amid much recent American work on the problem of informal constitutional change, this article stakes out a distinctive position. I argue that theories of constitutional change in the US must address the question of the relationship between the “small c” and “big C” Constitution and treat seriously the possibility of conflict between them. I stress the unavoidable role the text of the Constitution and structural doctrines of federalism and separation of powers play in this relationship and thus in constitutional change, both formal and informal. I therefore counsel against theories that rely solely on a practice-based approach or analogies between “small c” constitutional developments and British or Commonwealth traditions of the “unwritten” constitution and constitutional “conventions.” The alternative I advocate is to approach constitutional change from a historicist perspective that focuses attention on state building and the creation of new institutional capacities. This approach will allow us to make progress by highlighting that there can be multiple constitutional orders in a given historical era, thus accounting for the conflictual nature of contemporary constitutional development in the US.

  10. Transnational Constitutional Law

    NARCIS (Netherlands)

    Zumbansen, P (Peer); K.I. Bhatt (Kinnari)

    2018-01-01

    textabstractThis chapter provides an overview of the emerging field of transnational constitutional law (TCL). Whilst questions of constitutional law are typically discussed in the context of a specific domestic legal setting, a salient strategy of TCL is to understand constitutional law and its

  11. Right Product, Wrong Packaging: Not 'Constitution', but 'Constitutional Charter'

    Directory of Open Access Journals (Sweden)

    John Law

    2007-05-01

    Full Text Available The article seeks to locate the principal cause of Europe’s prevailing ratification crisis in the inappropriate title arrived at in the European Convention, Treaty Establishing a Constitution for Europe. This over-ambitious styling led the media to characterise the text as simply an ‘EU Constitution’. Yet, the text was not a Constitution as we traditionally understand the term, i.e. the founding document of a State: scholars are agreed that the EU is not, and will not become upon ratification, a State.In terms of substance, whilst the text certainly strengthened some emerging constitutional aspects, it was not a major departure from the status quo like the Single European Act and Treaty on European Union had been; and it remained technically a treaty like all its predecessors. Arguably, therefore, it did not require referenda to ratify. However, confusion over the scale and importance of what was proposed, stemming from ambiguity in the title, pushed politicians down this unfortunate path.The article identifies a high level of consensus among commentators as to the true nature of the text: most are happy designating it a treaty (noun with constitutional (adjective aspects. The early proposed title Constitutional Treaty for Europe was arguably, therefore, the correct one; but it is now too late to choose this option, as the terms Constitution and Constitutional Treaty have already been muddled in debate. A more distinctive change is required. One idea could be to follow the principle employed elsewhere in the text of codifying the generally accepted but presently unwritten legal concepts of the European Court of Justice, as was done for example for ‘primacy’ and ‘direct effect’. The Court has characterised the EU treaties as a ‘constitutional charter’ for over twenty years now, and on this basis a modified title could read Treaty Establishing a Constitutional Charter for Europe. Importantly, the term ‘charter’ is recognised

  12. Distribution of biomass and nutrients in lodgepole pine/bitterbrush ecosystems in central Oregon.

    Science.gov (United States)

    Susan N. Little; Laurl J. Shainsky

    1992-01-01

    We investigated the distribution of biomass and nutrients in lodgepole pine (Pinus contorta var. murryana Dougl.) ecosystems on pumice soils in south-central Oregon. Sixty-three trees were sampled to develop equations for estimating dry weights of tree crowns, boles, bark, and coarse roots from diameter at breast height and...

  13. Assimilating satellite-based canopy height within an ecosystem model to estimate aboveground forest biomass

    Science.gov (United States)

    Joetzjer, E.; Pillet, M.; Ciais, P.; Barbier, N.; Chave, J.; Schlund, M.; Maignan, F.; Barichivich, J.; Luyssaert, S.; Hérault, B.; von Poncet, F.; Poulter, B.

    2017-07-01

    Despite advances in Earth observation and modeling, estimating tropical biomass remains a challenge. Recent work suggests that integrating satellite measurements of canopy height within ecosystem models is a promising approach to infer biomass. We tested the feasibility of this approach to retrieve aboveground biomass (AGB) at three tropical forest sites by assimilating remotely sensed canopy height derived from a texture analysis algorithm applied to the high-resolution Pleiades imager in the Organizing Carbon and Hydrology in Dynamic Ecosystems Canopy (ORCHIDEE-CAN) ecosystem model. While mean AGB could be estimated within 10% of AGB derived from census data in average across sites, canopy height derived from Pleiades product was spatially too smooth, thus unable to accurately resolve large height (and biomass) variations within the site considered. The error budget was evaluated in details, and systematic errors related to the ORCHIDEE-CAN structure contribute as a secondary source of error and could be overcome by using improved allometric equations.

  14. Forest biomass variation in Southernmost Brazil: the impact of Araucaria trees.

    Science.gov (United States)

    Rosenfield, Milena Fermina; Souza, Alexandre F

    2014-03-01

    A variety of environmental and biotic factors determine vegetation growth and affect plant biomass accumulation. From temperature to species composition, aboveground biomass storage in forest ecosystems is influenced by a number of variables and usually presents a high spatial variability. With this focus, the aim of the study was to evaluate the variables affecting live aboveground forest biomass (AGB) in Subtropical Moist Forests of Southern Brazil, and to analyze the spatial distribution of biomass estimates. Data from a forest inventory performed in the State of Rio Grande do Sul, Southern Brazil, was used in the present study. Thirty-eight 1-ha plots were sampled and all trees with DBH > or = 9.5cm were included for biomass estimation. Values for aboveground biomass were obtained using published allometric equations. Environmental and biotic variables (elevation, rainfall, temperature, soils, stem density and species diversity) were obtained from the literature or calculated from the dataset. For the total dataset, mean AGB was 195.2 Mg/ha. Estimates differed between Broadleaf and Mixed Coniferous-Broadleaf forests: mean AGB was lower in Broadleaf Forests (AGB(BF)=118.9 Mg/ha) when compared to Mixed Forests (AGB(MF)=250.3 Mg/ha). There was a high spatial and local variability in our dataset, even within forest types. This condition is normal in tropical forests and is usually attributed to the presence of large trees. The explanatory multiple regressions were influenced mainly by elevation and explained 50.7% of the variation in AGB. Stem density, diversity and organic matter also influenced biomass variation. The results from our study showed a positive relationship between aboveground biomass and elevation. Therefore, higher values of AGB are located at higher elevations and subjected to cooler temperatures and wetter climate. There seems to be an important contribution of the coniferous species Araucaria angustifolia in Mixed Forest plots, as it presented

  15. Below-ground biomass production and allometric relationships of eucalyptus coppice plantation in the central highlands of Madagascar

    International Nuclear Information System (INIS)

    Razakamanarivo, Ramarson H.; Razakavololona, Ando; Razafindrakoto, Marie-Antoinette; Vieilledent, Ghislain; Albrecht, Alain

    2012-01-01

    Short rotations of Eucalyptus plantations under coppice regime are extensively managed for wood production in Madagascar. Nevertheless, little is known about their biomass production and partitioning and their potential in terms of carbon sequestration. If above-ground biomass (AGB) can be estimated based on established allometric relations, below-ground (BGB) estimates are much less common. The aim of this work was to develop allometric equations to estimate biomass of these plantations, mainly for the root components. Data from 9 Eucalyptus robusta stands (47–87 years of plantation age, 3–5 years of coppice-shoot age) were collected and analyzed. Biomass of 3 sampled trees per stand was determined destructively. Dry weight of AGB components (leaves, branches and stems) were estimated as a function of basal area of all shoots per stump and dry weight for BGB components (mainly stump, coarse root (CR) and medium root (MR)) were estimated as a function of stump circumference. Biomass was then computed using allometric equations from stand inventory data. Stand biomass ranged from 102 to 130 Mg ha −1 with more than 77% contained in the BGB components. The highest dry weight was allocated in the stump and in the CR (51% and 42% respectively) for BGB parts and in the stem (69%) for AGB part. Allometric relationships developed herein could be applied to other Eucalyptus plantations which present similar stand density and growing conditions; anyhow, more is needed to be investigated in understanding biomass production and partitioning over time for this kind of forest ecosystem. -- Highlights: ► We studied the potential of old eucalyptus coppices in Madagascar to mitigate global warming. ► Biomass measurement, mainly for below-ground BGB (stump, coarse-medium-and fine roots) was provided. ► BGB allometry relationships for short rotation forestry under coppice were established. ► BGB were found to be important with their 102-130MgC ha -1 (<77% of the C in

  16. Bio energy: Production of Biomass; Produksjon av biomasse

    Energy Technology Data Exchange (ETDEWEB)

    Noreng, Katrina; Indergaard, Mentz; Liodden, Ole Joergen; Hohle, Erik Eid; Sandberg, Eiliv

    2001-07-01

    This is Chapter 2 of the book ''Bio energy - Environment, technique and market''. Its main sections are: (1) Biomass resources in Norway, (2) The foundation - photosynthesis, (3) Biomass from forestry, (4) Biomass from peat lands, (5) Biomass from agriculture and (6) Biomass from lakes and sea. The exposition largely describes the conditions in Norway, where the use of bio energy can be increased from 15 TWh to 35 TWh using available technology. At present, water-borne heating systems are not extensively used in Norway and 30% of the biomass that is cut in the forests remains there as waste. Using this waste for energy generation would not only contribute to reduce the emission of greenhouse gases, but would often lead to improved forest rejuvenation. Use of a few per thousand of the Norwegian peat lands would produce 2 - 3 TWh. According to calculations, along the coast of Norway, there are at least 15 mill tonnes of kelp and sea tangle and these resources can be utilized in a sustainable way.

  17. Analytical and numerical treatment of the heat conduction equation obtained via time-fractional distributed-order heat conduction law

    Science.gov (United States)

    Želi, Velibor; Zorica, Dušan

    2018-02-01

    Generalization of the heat conduction equation is obtained by considering the system of equations consisting of the energy balance equation and fractional-order constitutive heat conduction law, assumed in the form of the distributed-order Cattaneo type. The Cauchy problem for system of energy balance equation and constitutive heat conduction law is treated analytically through Fourier and Laplace integral transform methods, as well as numerically by the method of finite differences through Adams-Bashforth and Grünwald-Letnikov schemes for approximation derivatives in temporal domain and leap frog scheme for spatial derivatives. Numerical examples, showing time evolution of temperature and heat flux spatial profiles, demonstrate applicability and good agreement of both methods in cases of multi-term and power-type distributed-order heat conduction laws.

  18. Estimation of aerial biomass of Lychnophora ericoides (Mart.

    Directory of Open Access Journals (Sweden)

    Brunno Santana de Andrade

    2007-07-01

    Full Text Available For sustainable use of native plant species, knowledge of the amount of harvestable biomass is necessary. This study presents data on allometric relationships of Lychnophora ericoides Mart. (Asteraceae, an extractive resource in the Cerrado region of Brazil. On the Fazenda Água Limpa (15º 45'S, 47º 57'W of the Universidade de Brasilia, 38 individuals of this species were measured in the field, the parts above ground were harvested, separated into components and oven dried. The best regression equations to estimate biomass were geometric and the best fit was between total height and total biomass (r² = 0.923. The economically useful portions, the leaves and branches accounted for approximately 20% of total above ground dry weight, but when used as the dependent variable, the strength of the relationship decreased (r² = 0.694. The relationship between branch diameter and leaf biomass was similar to that between height and leaf dry weight (r² = 0.600. The relation between the number of leaves and their biomass was linear but weak. The development of these equations is the first step towards the implementation of plans for sustainable use of this species.Para o uso sustentável das espécies vegetais nativas o conhecimento da quantidade de biomassa disponível é necessário. O objetivo deste estudo foi verificar as relações alométricas para Lychnophora ericoides Mart., um recurso extrativista importante na região dos Cerrados. Na Fazenda Água Limpa da Universidade de Brasília, 38 indivíduos desta espécie foram medidas no campo, a parte aérea foi cortada, separada em componentes de folhas, galhos e tronco e estas componentes foram secas e pesadas. As melhores equações de regressão para estimar a biomassa foram geométricas e o melhor ajuste foi entre altura total e biomassa total (r² = 0,923. As partes economicamente exploradas, as folhas e ramos, contribuíram com aproximadamente 20% do peso seco total desta espécie, mas a equa

  19. Biomass recalcitrance

    DEFF Research Database (Denmark)

    Felby, Claus

    2009-01-01

    Alternative and renewable fuels derived from lignocellulosic biomass offer a promising alternative to conventional energy sources, and provide energy security, economic growth, and environmental benefits. However, plant cell walls naturally resist decomposition from microbes and enzymes - this co......Alternative and renewable fuels derived from lignocellulosic biomass offer a promising alternative to conventional energy sources, and provide energy security, economic growth, and environmental benefits. However, plant cell walls naturally resist decomposition from microbes and enzymes...... - this collective resistance is known as "biomass recalcitrance." Breakthrough technologies are needed to overcome barriers to developing cost-effective processes for converting biomass to fuels and chemicals. This book examines the connection between biomass structure, ultrastructure, and composition......, to resistance to enzymatic deconstruction, with the aim of discovering new cost-effective technologies for biorefineries. It contains chapters on topics extending from the highest levels of biorefinery design and biomass life-cycle analysis, to detailed aspects of plant cell wall structure, chemical treatments...

  20. Constitutional Rights in Indonesia

    OpenAIRE

    Judhariksawan

    2018-01-01

    The constitution is fundamental to the life of the modern state as a major foothold in state governance. Includes the guarantee of constitutional rights of citizens. The The constitution is the basis of state organizers to be implemented so that the state is obliged to guarantee the fulfillment of citizens' constitutional rights. Human rights have become an important part of the modern constitution. This study will describe how human rights guarantees become part of consti...

  1. Major Biomass Conference

    Science.gov (United States)

    Top Scientists, Industry and Government Leaders to Gather for Major Biomass Conference America, South America and Europe will focus on building a sustainable, profitable biomass business at the Third Biomass Conference of the Americas in Montreal. Scheduled presentations will cover all biomass

  2. Influence of acidification and aluminium on the density and biomass of lotic benthic invertebrates

    Energy Technology Data Exchange (ETDEWEB)

    Allard, M.; Moreau, G.

    1986-10-01

    Experiments were carried out in plasticized wooden channels fed by a small creek in the Reserve des Laurentides, 80 km north of Quebec city. Channels were naturally colonized by invertebrates for 65 d before treatment. Treated channels were acidified in August with dilute H/sub 2/SO/sub 4/ only, or with acid plus a solution of Al sulfate (final concentration of 0.19 mg L/sup -1/). The control channel received creek water only (pH 6.3 to 6.9). The addition of Al had no effect on invertebrate density and biomass. After 73 d of acidification, invertebrate densities were only one third the number found in the control channel. Invertebrate biomass was not different within channels, although biomass was generally higher in the two acidified channels. Difference in densities between acidified and non-acidified channels was attributed to lack of colonization and not to an increase in drift. Microtendipes, a large and resistant larva of Chironomidae constituted a large fraction of the biomass, largely outweighing numerous very small larvae. Effects on the density were attributed to the direct effect of low pH and not to indirect action through food limitations. 22 refs.

  3. Biomass equations for forest regrowth in the eastern Amazon using randomized branch sampling Equações alométricas para estimativa de biomassa de floresta secundária na Amazônia Oriental usando amostragem aleatória de ramos

    Directory of Open Access Journals (Sweden)

    Mark Jonathan Ducey

    2009-01-01

    Full Text Available Forest regrowth occupies an extensive and increasing area in the Amazon basin, but accurate assessment of the impact of regrowth on carbon and nutrient cycles has been hampered by a paucity of available allometric equations. We develop pooled and species-specific equations for total aboveground biomass for a study site in the eastern Amazon that had been abandoned for 15 years. Field work was conducted using randomized branch sampling, a rapid technique that has seen little use in tropical forests. High consistency of sample paths in randomized branch sampling, as measured by the standard error of individual paths (14%, suggests the method may provide substantial efficiencies when compared to traditional procedures. The best fitting equations in this study used the traditional form Y=a×DBHb, where Y is biomass, DBH is diameter at breast height, and a and b are both species-specific parameters. Species-specific equations of the form Y=a(BA×H, where Y is biomass, BA is tree basal area, H is tree height, and a is a species-specific parameter, fit almost as well. Comparison with previously published equations indicated errors from -33% to +29% would have occurred using off-site relationships. We also present equations for stemwood, twigs, and foliage as biomass components.Florestas secundárias ocupam uma área extensa e crescente na bacia Amazônica, porém determinações acuradas do impacto dessas florestas nos ciclos de carbono e nutrientes têm sido dificultadas pelo número reduzido de equações alométricas. Neste estudo, nós desenvolvemos equações em nível de comunidade e espécies individuais para estimar a biomassa total da parte aérea de uma floresta secundária com 15 anos de idade na Amazônia oriental. O trabalho de campo utilizou amostragem aleatória de ramos, que é uma técnica rápida, porém pouco utilizada em florestas tropicais. Baseada no erro padrão da série de segmentos individuais (14%, a consistência da s

  4. Biomass treatment method

    Science.gov (United States)

    Friend, Julie; Elander, Richard T.; Tucker, III; Melvin P.; Lyons, Robert C.

    2010-10-26

    A method for treating biomass was developed that uses an apparatus which moves a biomass and dilute aqueous ammonia mixture through reaction chambers without compaction. The apparatus moves the biomass using a non-compressing piston. The resulting treated biomass is saccharified to produce fermentable sugars.

  5. The Constitutional Amendment Process

    Science.gov (United States)

    Chism, Kahlil

    2005-01-01

    This article discusses the constitutional amendment process. Although the process is not described in great detail, Article V of the United States Constitution allows for and provides instruction on amending the Constitution. While the amendment process currently consists of six steps, the Constitution is nevertheless quite difficult to change.…

  6. Structure preserving transformations for Newtonian Lie-admissible equations

    International Nuclear Information System (INIS)

    Cantrijn, F.

    1979-01-01

    Recently, a new formulation of non-conservative mechanics has been presented in terms of Hamilton-admissible equations which constitute a generalization of the conventional Hamilton equations. The algebraic structure entering the Hamilton-admissible description of a non-conservative system is that of a Lie-admissible algebra. The corresponding geometrical treatment is related to the existence of a so-called symplectic-admissible form. The transformation theory for Hamilton-admissible systems is currently investigated. The purpose of this paper is to describe one aspect of this theory by identifying the class of transformations which preserve the structure of Hamilton-admissible equations. Necessary and sufficient conditions are established for a transformation to be structure preserving. Some particular cases are discussed and an example is worked out

  7. Constitutional Politics, Constitutional Texts and Democratic Variety in Central and Eastern Europe

    OpenAIRE

    Blokker, Paul

    2008-01-01

    In the paper, it is argued that democratization in Central and Eastern Europe involves important forms of differentiation of democracy, rather than merely convergence to a singular – liberal-democratic, constitutional - model. One way of taking up democratic differentiation in post-communist societies is by analysing the constitutional documents of the new democratic orders, and the constitutional politics leading to the foundational documents. In a first step, the paper analyses constitution...

  8. Equação de biomassa e estoque de carbono do pinhão manso, no município de Viçosa, MG Biomass equation and carbon stock of jatropha crop, in Viçosa, Minas Gerais, Brazil

    Directory of Open Access Journals (Sweden)

    Diego de Paula Toledo

    2012-11-01

    Full Text Available O presente trabalho teve como objetivo estimar equações de biomassa e o estoque de carbono da cultura do Pinhão Manso (Jatrophacurcas L.. A área estudada localiza-se no município de Viçosa, MG. O plantio foi realizado em espaçamento 3,5x3,0m, em 4,64ha. Para quantificação da biomassa, foi utilizado o método direto e destrutivo, aplicado às árvores-amostra, que foram selecionadas de acordo com as medidas da altura, do diâmetro das copas e do número de ramos. A determinação da biomassa de cada árvore foi obtida pelo método da proporcionalidade. Os modelos testados foram adaptados de Spurr e de Schumacher & Hall, para biomassa aérea e biomassa total (biomassa aérea mais biomassa de raízes pivotantes. O estoque de carbono foi estimado através da multiplicação da biomassa seca pelo teor de carbono da matéria seca, que foi obtido pelo método da calcinação em mufla. A estimativa do CO2 equivalente estocado foi obtida pela multiplicação do estoque de carbono pelo fator 44/12. A equação que obteve melhor ajuste e que foi utilizada para determinação do estoque de carbono deste estudo foi a de Spurr, com os dados de biomassa total, B=0,7601*(DC2*H0,8949, em que B = biomassa (kg; DC = diâmetro de copa (m; e H = altura (m. O estoque de carbono encontrado da cultura, no quarto ano, foi de 6,79MgC ha-1, correspondendo a 24,89Mg CO2(eq ha-1. Os resultados mostram que o pinhão-manso é ambientalmente viável para elaboração de projetos MDL de florestamento/reflorestamento ou em projetos de carbono para mercados voluntários, agregando renda ao produtor rural e melhorando a atratividade financeira da cultura.This study had the objectives to estimate equations of biomass and carbon stock of Jatropha (Jatrophacurcas L.. The area of this study is located in Viçosa, Minas Gerais, planting carried out in 3.5x3.0m spacing at 4.64ha. To biomass quantification, we used the direct destructive method, applied to trees, which were

  9. Biomass Energy Basics | NREL

    Science.gov (United States)

    Biomass Energy Basics Biomass Energy Basics We have used biomass energy, or "bioenergy" keep warm. Wood is still the largest biomass energy resource today, but other sources of biomass can landfills (which are methane, the main component in natural gas) can be used as a biomass energy source. A

  10. Integration of deep geothermal energy and woody biomass conversion pathways in urban systems

    OpenAIRE

    Moret, Stefano; Peduzzi, Emanuela; Gerber, Léda; Maréchal, François

    2016-01-01

    Urban systems account for about two-thirds of global primary energy consumption and energy-related greenhouse gas emissions, with a projected increasing trend. Deep geothermal energy and woody biomass can be used for the production of heat, electricity and biofuels, thus constituting a renewable alternative to fossil fuels for all end-uses in cities: heating, cooling, electricity and mobility. This paper presents a methodology to assess the potential for integrating deep geothermal energy and...

  11. Attached biomass growth and substrate utilization rate in a moving bed biofilm reactor

    Directory of Open Access Journals (Sweden)

    J. J. Marques

    2008-12-01

    Full Text Available A moving bed bioreactor containing cubes of polyether foam immersed in a synthetic wastewater (an aqueous mixture of meat extract, yeast extract, dextrose, meat peptone, ammonium chloride, potassium chloride, sodium chloride, sodium bicarbonate, potassium mono-hydrogen-phosphate and magnesium sulphate was used to evaluate bacterial growth and biomass yield parameters based on Monod's equation. The wastewater was supplied in the bottom of the equipment flowing ascending in parallel with a diffused air current that provided the mixing of the reactor content. Suspended and attached biomass concentration was measured through gravimetric methods. Good agreement was found between experimental kinetic parameters values and those obtained by other researchers. The only significant difference was the high global biomass content about 2 times the values obtained in conventional processes, providing high performance with volumetric loading rates up to 5.5 kg COD/m³/d.

  12. Eigenvalues of the simplified ideal MHD ballooning equation

    International Nuclear Information System (INIS)

    Paris, R.B.; Auby, N.; Dagazian, R.Y.

    1986-01-01

    The investigation of the spectrum of the simplified differential equation describing the variation of the amplitude of the ideal MHD ballooning instability along magnetic field lines constitutes a multiparameter Schroedinger eigenvalue problem. An exact eigenvalue relation for the discrete part of the spectrum is obtained in terms of the oblate spheroidal functions. The dependence of the eigenvalues lambda on the two free parameters γ 2 and μ 2 of the equation is discussed, together with certain analytical approximations in the limits of small and large γ 2 . A brief review of the principal properties of the spheroidal functions is given in an appendix

  13. ADI splitting schemes for a fourth-order nonlinear partial differential equation from image processing

    KAUST Repository

    Calatroni, Luca

    2013-08-01

    We present directional operator splitting schemes for the numerical solution of a fourth-order, nonlinear partial differential evolution equation which arises in image processing. This equation constitutes the H -1-gradient flow of the total variation and represents a prototype of higher-order equations of similar type which are popular in imaging for denoising, deblurring and inpainting problems. The efficient numerical solution of this equation is very challenging due to the stiffness of most numerical schemes. We show that the combination of directional splitting schemes with implicit time-stepping provides a stable and computationally cheap numerical realisation of the equation.

  14. ADI splitting schemes for a fourth-order nonlinear partial differential equation from image processing

    KAUST Repository

    Calatroni, Luca; Dü ring, Bertram; Schö nlieb, Carola-Bibiane

    2013-01-01

    We present directional operator splitting schemes for the numerical solution of a fourth-order, nonlinear partial differential evolution equation which arises in image processing. This equation constitutes the H -1-gradient flow of the total variation and represents a prototype of higher-order equations of similar type which are popular in imaging for denoising, deblurring and inpainting problems. The efficient numerical solution of this equation is very challenging due to the stiffness of most numerical schemes. We show that the combination of directional splitting schemes with implicit time-stepping provides a stable and computationally cheap numerical realisation of the equation.

  15. Biomass CCS study

    Energy Technology Data Exchange (ETDEWEB)

    Cavezzali, S.

    2009-11-15

    The use of biomass in power generation is one of the important ways in reducing greenhouse gas emissions. Specifically, the cofiring of biomass with coal could be regarded as a common feature to any new build power plant if a sustainable supply of biomass fuel is readily accessible. IEA GHG has undertaken a techno-economic evaluation of the use of biomass in biomass fired and co-fired power generation, using post-combustion capture technology. This report is the result of the study undertaken by Foster Wheeler Italiana.

  16. A class of constitutive relations with internal variable derivatives. Derivation from homogenization and initial value problem

    International Nuclear Information System (INIS)

    Andrieux, S.; Joussemet, M.; Lorentz, E.

    1996-01-01

    A general framework for deriving and using a class of constitutive laws incorporating spatial gradients of internal variables is presented. It uses two basic ingredients: a derivation of such models by homogenization techniques and a reformulation of the evolution equation at the scale of the whole structure. (orig.)

  17. Spatio-temporal changes in biomass carbon sinks in China's forests from 1977 to 2008.

    Science.gov (United States)

    Guo, Zhaodi; Hu, Huifeng; Li, Pin; Li, Nuyun; Fang, Jingyun

    2013-07-01

    Forests play a leading role in regional and global carbon (C) cycles. Detailed assessment of the temporal and spatial changes in C sinks/sources of China's forests is critical to the estimation of the national C budget and can help to constitute sustainable forest management policies for climate change. In this study, we explored the spatio-temporal changes in forest biomass C stocks in China between 1977 and 2008, using six periods of the national forest inventory data. According to the definition of the forest inventory, China's forest was categorized into three groups: forest stand, economic forest, and bamboo forest. We estimated forest biomass C stocks for each inventory period by using continuous biomass expansion factor (BEF) method for forest stands, and the mean biomass density method for economic and bamboo forests. As a result, China's forests have accumulated biomass C (i.e., biomass C sink) of 1896 Tg (1 Tg=10(12) g) during the study period, with 1710, 108 and 78 Tg C in forest stands, and economic and bamboo forests, respectively. Annual forest biomass C sink was 70.2 Tg C a(-1), offsetting 7.8% of the contemporary fossil CO2 emissions in the country. The results also showed that planted forests have functioned as a persistent C sink, sequestrating 818 Tg C and accounting for 47.8% of total C sink in forest stands, and that the old-, mid- and young-aged forests have sequestrated 930, 391 and 388 Tg C from 1977 to 2008. Our results suggest that China's forests have a big potential as biomass C sink in the future because of its large area of planted forests with young-aged growth and low C density.

  18. Transnational Constitutional Law

    OpenAIRE

    Zumbansen, P (Peer); Bhatt, Kinnari

    2018-01-01

    textabstractThis chapter provides an overview of the emerging field of transnational constitutional law (TCL). Whilst questions of constitutional law are typically discussed in the context of a specific domestic legal setting, a salient strategy of TCL is to understand constitutional law and its values by placing them ‘in context’ with existing and evolving cultural norms and political, social and economic discourses and struggles. Drawing on socio-legal investigations into the relationships ...

  19. Biomass pretreatment

    Science.gov (United States)

    Hennessey, Susan Marie; Friend, Julie; Elander, Richard T; Tucker, III, Melvin P

    2013-05-21

    A method is provided for producing an improved pretreated biomass product for use in saccharification followed by fermentation to produce a target chemical that includes removal of saccharification and or fermentation inhibitors from the pretreated biomass product. Specifically, the pretreated biomass product derived from using the present method has fewer inhibitors of saccharification and/or fermentation without a loss in sugar content.

  20. Analysis and co-ordination of the activities concerning gasification of biomass. Summary country report, Denmark and Norway

    International Nuclear Information System (INIS)

    Stoholm, P.; Olsen, A.

    1996-11-01

    The analysis summarises the coordination of activities concerning the gasification of biomass in Denmark and Norway. The total quantity of available biomass for energy production in Denmark corresponds to ca. 115 PJ of which ca. 40% is utilized - and this constitutes ca. 6% of the country's total energy consumption. The resulting energy from biomass is currently mostly used for heating purposes utilizing small wood/straw household or farm stoves in addition to ca. 100 district heating systems. There is a tendency to use biomass fuels for electric power production as in the case of all major waste incineration plants and about 10 fully or partly wood/straw-fired cogeneration plants which are found within the range of 2 -20 MWe. A table shows details of all Danish biomass gasification plants and information is given on the types of biomass, under the titles of residue products and energy crops, most relevant to energy production in Denmark. Data is presented on the consumption of renewable energy in Denmark, recalculated in fuel equivalents, and Danish national energy policy and related legislation are described. Information on Norway's use of biomass as fuel is given under the headings of primary consumption, biomass sources and use, legislation, and brief evaluations of commercial gasification plants, pilot and demonstration plants, and laboratory plants and studies. It has recently been decided to speed up the development of small-scale gasification plants for combined heat and electricity production using biomass as fuel in Denmark. Total Norwegian energy consumption is 25% higher than Denmark's, and biomass fuels cover only 3.6% of this. (ARW) 32 refs

  1. An anisotropic elastoplastic constitutive formulation generalised for orthotropic materials

    Science.gov (United States)

    Mohd Nor, M. K.; Ma'at, N.; Ho, C. S.

    2018-03-01

    This paper presents a finite strain constitutive model to predict a complex elastoplastic deformation behaviour that involves very high pressures and shockwaves in orthotropic materials using an anisotropic Hill's yield criterion by means of the evolving structural tensors. The yield surface of this hyperelastic-plastic constitutive model is aligned uniquely within the principal stress space due to the combination of Mandel stress tensor and a new generalised orthotropic pressure. The formulation is developed in the isoclinic configuration and allows for a unique treatment for elastic and plastic orthotropy. An isotropic hardening is adopted to define the evolution of plastic orthotropy. The important feature of the proposed hyperelastic-plastic constitutive model is the introduction of anisotropic effect in the Mie-Gruneisen equation of state (EOS). The formulation is further combined with Grady spall failure model to predict spall failure in the materials. The proposed constitutive model is implemented as a new material model in the Lawrence Livermore National Laboratory (LLNL)-DYNA3D code of UTHM's version, named Material Type 92 (Mat92). The combination of the proposed stress tensor decomposition and the Mie-Gruneisen EOS requires some modifications in the code to reflect the formulation of the generalised orthotropic pressure. The validation approach is also presented in this paper for guidance purpose. The \\varvec{ψ} tensor used to define the alignment of the adopted yield surface is first validated. This is continued with an internal validation related to elastic isotropic, elastic orthotropic and elastic-plastic orthotropic of the proposed formulation before a comparison against range of plate impact test data at 234, 450 and {895 ms}^{-1} impact velocities is performed. A good agreement is obtained in each test.

  2. CAN THE MUSLIM WORLD BORROW FROM INDONESIAN CONSTITUTIONAL REFORM? A Comparative Constitutional Approach

    Directory of Open Access Journals (Sweden)

    Nadirsyah Hosen

    2007-06-01

    Full Text Available This paper attempts to analytically examine the possibility of constitutional borrowing for the Muslim world regardless the differences in history, system, culture, language, and cha­racteristics. It discusses this issue by looking at the arguments put forth by the oppo­nents of comparative cons­titutional interpre­tation and their counter arguments. It will consider materials from Canada, USA, South Africa, Singapore, Malaysia, and Hungary, taking the position that constitutional borrowing can be justified. The paper argues that the 1999-2002 Indonesian constitutional reform should be taken into account by other Muslim countries in undertaking their constitutional reform. The substantive approach of the Shari‘ah that has been used in Indonesia has shown that Muslim world can reform its constitutions without the “assistance” of Western foreign policy. Indo­nesian constitutional reform has demonstrated that Islamic constitutionalism comes from within Islamic teaching and the Islamic community itself; it is a home grown product.

  3. Methods for pretreating biomass

    Science.gov (United States)

    Balan, Venkatesh; Dale, Bruce E; Chundawat, Shishir; Sousa, Leonardo

    2017-05-09

    A method for pretreating biomass is provided, which includes, in a reactor, allowing gaseous ammonia to condense on the biomass and react with water present in the biomass to produce pretreated biomass, wherein reactivity of polysaccharides in the biomass is increased during subsequent biological conversion as compared to the reactivity of polysaccharides in biomass which has not been pretreated. A method for pretreating biomass with a liquid ammonia and recovering the liquid ammonia is also provided. Related systems which include a biochemical or biofuel production facility are also disclosed.

  4. Evaluation of total aboveground biomass and total merchantable biomass in Missouri

    Science.gov (United States)

    Michael E. Goerndt; David R. Larsen; Charles D. Keating

    2014-01-01

    In recent years, the state of Missouri has been converting to biomass weight rather than volume as the standard measurement of wood for buying and selling sawtimber. Therefore, there is a need to identify accurate and precise methods of estimating whole tree biomass and merchantable biomass of harvested trees as well as total standing biomass of live timber for...

  5. REMOVAL OF ARSENIC FROM AN AQUEOUS SOLUTION BY PRETREATED WASTE TEA FUNGAL BIOMASS

    Directory of Open Access Journals (Sweden)

    S. Mamisahebei , Gh. R. Jahed Khaniki, A. Torabian, S. Nasseri, K. Naddafi

    2007-04-01

    Full Text Available Arsenic contamination in water poses a serious threat on human health. The tea fungus known as Kombucha is a waste produced during black tea fermentation. The objective of this study was to examine the main aspect of a possible strategy for the removal of arsenates employing tea fungal biomass. The pretreatment of biomass with FeCl3 was found to improve the biosorption efficiency. Arsenics uptake was found to be rapid for all concentrations and reached to 79% of equilibrium capacity of biosorption in 20 min and reached equilibrium in 90 min. The pseudo second-order and first-order models described the biosorption kinetics of As (V with good correlation coefficient (R2>0.93 and better than the other equations. The data obtained from the experiment of biosorption isotherm were analyzed using the Freundlich and Langmuir isotherm models. The equation described the isotherm of As (V biosorption with relatively high correlation coefficient (R2>0.93. According to the Langmuir model, the maximum uptake capacities (qm of tea fungal biomass for As (V were obtained 3.9810-3 mmol/gr. The effect of Na+, K+, Mg+2 and Ca+2 on equilibrium capacities of As was not significant. The variation of sorption efficiency with pH showed that optimum biosorption takes place in the pH ranges of 6 to 8. Promising results were obtained in laboratory experiments and effective As (V removals were observed.

  6. DUE GlobBiomass - Estimates of Biomass on a Global Scale

    Science.gov (United States)

    Eberle, J.; Schmullius, C.

    2017-12-01

    For the last three years, a new ESA Data User Element (DUE) project had focussed on creating improved knowledge about the Essential Climate Variable Biomass. The main purpose of the DUE GlobBiomass project is to better characterize and to reduce uncertainties of AGB estimates by developing an innovative synergistic mapping approach in five regional sites (Sweden, Poland, Mexico, Kalimantan, South Africa) for the epochs 2005, 2010 and 2015 and for one global map for the year 2010. The project team includes leading Earth Observation experts of Europe and is linked through Partnership Agreements with further national bodies from Brazil, Canada, China, Russia and South Africa. GlobBiomass has demonstrated how EO observation data can be integrated with in situ measurements and ecological understanding to provide improved biomass estimates that can be effectively exploited by users. The target users had mainly be drawn from the climate and carbon cycle modelling communities and included users concerned with carbon emissions and uptake due to biomass changes within initiatives such as REDD+. GlobBiomass provided a harmonised structure that can be exploited to address user needs for biomass information, but will be capable of being progressively refined as new data and methods become available. This presentation will give an overview of the technical prerequisites and final results of the GlobBiomass project.

  7. Constitutional Issues--Watergate and the Constitution. Teaching with Documents.

    Science.gov (United States)

    National Archives and Records Administration, Washington, DC.

    When U.S. President Richard Nixon resigned in 1974 in the wake of the Watergate scandal, it was only the second time that impeachment of a president had been considered. Although the U.S. Constitution has provisions for a person removed from office to be indicted, there are no guidelines in the Constitution about a President who has resigned. The…

  8. Biomass torrefaction mill

    Science.gov (United States)

    Sprouse, Kenneth M.

    2016-05-17

    A biomass torrefaction system includes a mill which receives a raw biomass feedstock and operates at temperatures above 400 F (204 C) to generate a dusty flue gas which contains a milled biomass product.

  9. On the constitutive law of environment assisted fatigue: The physical meaning of the Paris type equations. Pt. 2

    International Nuclear Information System (INIS)

    Krausz, A.S.; Wu Xijia; Krausz, K.; Lian Zhiwen

    1992-01-01

    The physically based constitutive law of corrosion fatigue, derived in Part I from the principles of thermally activated processes and fracture kinetics, is applied for the representation of the crack growth rate over the whole stress intensity range. The behavior is expressed in terms of design and environmental factors and microstructural quantities. The constitutive law of fracture kinetics defines explicitly the effects of stress and temperature. Similarly, the role of the stress ratio R, the frequency and microstructure, follow rigorously. The influence of these factors on the crack growth rate and threshold behavior is discussed extensively. It is also demonstrated that fracture kinetics provides the framework for the detailed incorporation of corrosion chemical reaction and the associated diffusion processes. (orig.) [de

  10. Quantitative analysis of microbial biomass yield in aerobic bioreactor.

    Science.gov (United States)

    Watanabe, Osamu; Isoda, Satoru

    2013-12-01

    We have studied the integrated model of reaction rate equations with thermal energy balance in aerobic bioreactor for food waste decomposition and showed that the integrated model has the capability both of monitoring microbial activity in real time and of analyzing biodegradation kinetics and thermal-hydrodynamic properties. On the other hand, concerning microbial metabolism, it was known that balancing catabolic reactions with anabolic reactions in terms of energy and electron flow provides stoichiometric metabolic reactions and enables the estimation of microbial biomass yield (stoichiometric reaction model). We have studied a method for estimating real-time microbial biomass yield in the bioreactor during food waste decomposition by combining the integrated model with the stoichiometric reaction model. As a result, it was found that the time course of microbial biomass yield in the bioreactor during decomposition can be evaluated using the operational data of the bioreactor (weight of input food waste and bed temperature) by the combined model. The combined model can be applied to manage a food waste decomposition not only for controlling system operation to keep microbial activity stable, but also for producing value-added products such as compost on optimum condition. Copyright © 2013 The Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.

  11. Essential Medicines in National Constitutions

    Science.gov (United States)

    Toebes, Brigit; Hogerzeil, Hans

    2016-01-01

    Abstract A constitutional guarantee of access to essential medicines has been identified as an important indicator of government commitment to the progressive realization of the right to the highest attainable standard of health. The objective of this study was to evaluate provisions on access to essential medicines in national constitutions, to identify comprehensive examples of constitutional text on medicines that can be used as a model for other countries, and to evaluate the evolution of constitutional medicines-related rights since 2008. Relevant articles were selected from an inventory of constitutional texts from WHO member states. References to states’ legal obligations under international human rights law were evaluated. Twenty-two constitutions worldwide now oblige governments to protect and/or to fulfill accessibility of, availability of, and/or quality of medicines. Since 2008, state responsibilities to fulfill access to essential medicines have expanded in five constitutions, been maintained in four constitutions, and have regressed in one constitution. Government commitments to essential medicines are an important foundation of health system equity and are included increasingly in state constitutions. PMID:27781006

  12. A 1D thermomechanical network transition constitutive model coupled with multiple structural relaxation for shape memory polymers

    Science.gov (United States)

    Zeng, Hao; Xie, Zhimin; Gu, Jianping; Sun, Huiyu

    2018-03-01

    A new thermomechanical network transition constitutive model is proposed in the study to describe the viscoelastic behavior of shape memory polymers (SMPs). Based on the microstructure of semi-crystalline SMPs, a new simplified transformation equation is proposed to describe the transform of transient networks. And the generalized fractional Maxwell model is introduced in the paper to estimate the temperature-dependent storage modulus. In addition, a neo-KAHR theory with multiple discrete relaxation processes is put forward to study the structural relaxation of the nonlinear thermal strain in cooling/heating processes. The evolution equations of the time- and temperature-dependent stress and strain response are developed. In the model, the thermodynamical and mechanical characteristics of SMPs in the typical thermomechanical cycle are described clearly and the irreversible deformation is studied in detail. Finally, the typical thermomechanical cycles are simulated using the present constitutive model, and the simulation results agree well with the experimental results.

  13. A constitutive model for particulate-reinforced titanium matrix composites subjected to high strain rates and high temperatures

    Directory of Open Access Journals (Sweden)

    Song Wei-Dong

    2013-01-01

    Full Text Available Quasi-static and dynamic tension tests were conducted to study the mechanical properties of particulate-reinforced titanium matrix composites at strain rates ranging from 0.0001/s to 1000/s and at temperatures ranging from 20 °C to 650 °C Based on the experimental results, a constitutive model, which considers the effects of strain rate and temperature on hot deformation behavior, was proposed for particulate-reinforced titanium matrix composites subjected to high strain rates and high temperatures by using Zener-Hollomon equations including Arrhenius terms. All the material constants used in the model were identified by fitting Zener-Hollomon equations against the experimental results. By comparison of theoretical predictions presented by the model with experimental results, a good agreement was achieved, which indicates that this constitutive model can give an accurate and precise estimate for high temperature flow stress for the studied titanium matrix composites and can be used for numerical simulations of hot deformation behavior of the composites.

  14. The Causes of Failure of the European Constitution From the Perspective of the Constitution-Making Process

    Directory of Open Access Journals (Sweden)

    Robert Podolnjak

    2006-01-01

    Full Text Available The basic argument of the article is that the main causes of failure of the European Constitution stem from an inadequate preparation and implementation of a complex procedure of constitution-making for a federation of countries on a continental scale. This process includes the issues of temporal aspects of constitutionmaking, the subject of constitution-making, the text of the constitution, the strategy of constitutional ratifi cation and the constitution-makers themselves. The principal causes of failure of the European Constitution will be presented in the form of certain preliminary assumptions, which will then be examined in the light of certain comparative experiences of constitution-making in two federal systems – the American and the Swiss system. The primary mistakes of the European constitution-making are refl ected in the lack of an appropriate moment for making the constitution, in the vagueness of the document in terms of its constitutional or contractual quality, in the creation of a text of the Constitution which is completely incomprehensible to the average citizen, in the making of the Constitution without a vision or ambition, in the complete lack of any strategy of ratifi cation of the Constitution, in the insistence on the direct participation of the people in the adoption of the Constitution, which is legally and politically considered primarily an international treaty, and in badly managed media presentation and defence of the Constitution before the European public. The most important mistakes, crucial to the failure of the Constitution, are the ambivalent approach of the European constitutionmakers to the mode of ratifi cation of the Constitution, and their disregard of the constitution-making experience of other federal countries.

  15. Simulating the partitioning of biomass and nitrogen between roots and shoot in crop and grass plants

    NARCIS (Netherlands)

    Yin, X.; Schapendonk, A.H.C.M.

    2004-01-01

    Quantification of the assimilate partitioning between roots and shoot has been one of the components that need improvement in crop growth models. In this study we derived two equations for root-shoot partitioning of biomass and nitrogen (N) that hold for crops grown under steady-state conditions.

  16. Methods for producing and using densified biomass products containing pretreated biomass fibers

    Science.gov (United States)

    Dale, Bruce E.; Ritchie, Bryan; Marshall, Derek

    2015-05-26

    A process is provided comprising subjecting a quantity of plant biomass fibers to a pretreatment to cause at least a portion of lignin contained within each fiber to move to an outer surface of said fiber, wherein a quantity of pretreated tacky plant biomass fibers is produced; and densifying the quantity of pretreated tacky plant biomass fibers to produce one or more densified biomass particulates, wherein said biomass fibers are densified without using added binder.

  17. ECHR and national constitutional courts

    Directory of Open Access Journals (Sweden)

    Nastić Maja

    2015-01-01

    Full Text Available Comprising fundamental rights and freedoms and establishing the effective control system, the European Convention on Human Rights (ECHR encroaches upon the area that is traditional reserved for constitutional law. Although built on the doctrine reserved for international treaty law, the Convention goes beyond the traditional boundaries that exist between international and constitutional law. It has gradually infiltrated into the national legal systems. Constitutional courts have had the crucial role in this process. This paper will focus on the applicability of the ECHR in proceedings before national constitutional courts. Having in mind the jurisdiction of the national constitutional court, the ECHR may be applied in two ways: first, in the process of constitutional review by national constitutional courts and, second, in the process of deciding on constitutional complaints.

  18. The biomass file

    International Nuclear Information System (INIS)

    2010-01-01

    As biomass represents the main source of renewable energy to reach the 23 per cent objective in terms of energy consumption by 2020, a first article gives a synthetic overview of its definition, its origins, its possible uses, its share in the French energy mix, its role by 2020, strengths and weaknesses for its development, the growth potential of its market, and its implications in terms of employment. A second article outlines the assets of biomass, indicates the share of some crops in biomass energy production, and discusses the development of new resources and the possible energy valorisation of various by-products. Interviews about biomass market and development perspectives are proposed with representatives of institutions, energy industries and professional bodies concerned with biomass development and production. Other articles comments the slow development of biomass-based cogeneration, the coming into operation of a demonstration biomass roasting installation in Pau (France), the development potential of biogas in France, the project of bio natural gas vehicles in Lille, and the large development of biogas in Germany

  19. Energy production from biomass

    International Nuclear Information System (INIS)

    Bestebroer, S.I.

    1995-01-01

    The aim of the task group 'Energy Production from Biomass', initiated by the Dutch Ministry of Economic Affairs, was to identify bottlenecks in the development of biomass for energy production. The bottlenecks were identified by means of a process analysis of clean biomass fuels to the production of electricity and/or heat. The subjects in the process analysis are the potential availability of biomass, logistics, processing techniques, energy use, environmental effects, economic impact, and stimulation measures. Three categories of biomass are distinguished: organic residual matter, imported biomass, and energy crops, cultivated in the Netherlands. With regard to the processing techniques attention is paid to co-firing of clean biomass in existing electric power plants (co-firing in a coal-fired power plant or co-firing of fuel gas from biomass in a coal-fired or natural gas-fired power plant), and the combustion or gasification of clean biomass in special stand-alone installations. 5 figs., 13 tabs., 28 refs

  20. Biomass Characterization | Bioenergy | NREL

    Science.gov (United States)

    Characterization Biomass Characterization NREL provides high-quality analytical characterization of biomass feedstocks, intermediates, and products, a critical step in optimizing biomass conversion clear, amber liquid Standard Biomass Laboratory Analytical Procedures We maintain a library of

  1. Combined Multi-Temporal Optical and Radar Parameters for Estimating LAI and Biomass in Winter Wheat Using HJ and RADARSAR-2 Data

    Directory of Open Access Journals (Sweden)

    Xiuliang Jin

    2015-10-01

    Full Text Available Leaf area index (LAI and biomass are frequently used target variables for agricultural and ecological remote sensing applications. Ground measurements of winter wheat LAI and biomass were made from March to May 2014 in the Yangling district, Shaanxi, Northwest China. The corresponding remotely sensed data were obtained from the earth-observation satellites Huanjing (HJ and RADARSAT-2. The objectives of this study were (1 to investigate the relationships of LAI and biomass with several optical spectral vegetation indices (OSVIs and radar polarimetric parameters (RPPs, (2 to estimate LAI and biomass with combined OSVIs and RPPs (the product of OSVIs and RPPs (COSVI-RPPs, (3 to use multiple stepwise regression (MSR and partial least squares regression (PLSR to test and compare the estimations of LAI and biomass in winter wheat, respectively. The results showed that LAI and biomass were highly correlated with several OSVIs (the enhanced vegetation index (EVI and modified triangular vegetation index 2 (MTVI2 and RPPs (the radar vegetation index (RVI and double-bounce eigenvalue relative difference (DERD. The product of MTVI2 and DERD (R2 = 0.67 and RMSE = 0.68, p < 0.01 and that of MTVI2 and RVI (R2 = 0. 68 and RMSE = 0.65, p < 0.01 were strongly related to LAI, and the product of the optimized soil adjusted vegetation index (OSAVI and DERD (R2 = 0.79 and RMSE = 148.65 g/m2, p < 0.01 and that of EVI and RVI (R2 = 0. 80 and RMSE = 146.33 g/m2, p < 0.01 were highly correlated with biomass. The estimation accuracy of LAI and biomass was better using the COSVI-RPPs than using the OSVIs and RPPs alone. The results revealed that the PLSR regression equation better estimated LAI and biomass than the MSR regression equation based on all the COSVI-RPPs, OSVIs, and RPPs. Our results indicated that the COSVI-RPPs can be used to robustly estimate LAI and biomass. This study may provide a guideline for improving the estimations of LAI and biomass of winter wheat

  2. Constitutive modeling and structural analysis considering simultaneous phase transformation and plastic yield in shape memory alloys

    Science.gov (United States)

    Hartl, D. J.; Lagoudas, D. C.

    2009-10-01

    The new developments summarized in this work represent both theoretical and experimental investigations of the effects of plastic strain generation in shape memory alloys (SMAs). Based on the results of SMA experimental characterization described in the literature and additional testing described in this work, a new 3D constitutive model is proposed. This phenomenological model captures both the conventional shape memory effects of pseudoelasticity and thermal strain recovery, and additionally considers the initiation and evolution of plastic strains. The model is numerically implemented in a finite element framework using a return mapping algorithm to solve the constitutive equations at each material point. This combination of theory and implementation is unique in its ability to capture the simultaneous evolution of recoverable transformation strains and irrecoverable plastic strains. The consideration of isotropic and kinematic plastic hardening allows the derivation of a theoretical framework capturing the interactions between irrecoverable plastic strain and recoverable strain due to martensitic transformation. Further, the numerical integration of the constitutive equations is formulated such that objectivity is maintained for SMA structures undergoing moderate strains and large displacements. The implemented model has been used to perform 3D analysis of SMA structural components under uniaxial and bending loads, including a case of local buckling behavior. Experimentally validated results considering simultaneous transformation and plasticity in a bending member are provided, illustrating the predictive accuracy of the model and its implementation.

  3. Constitutive modeling and structural analysis considering simultaneous phase transformation and plastic yield in shape memory alloys

    International Nuclear Information System (INIS)

    Hartl, D J; Lagoudas, D C

    2009-01-01

    The new developments summarized in this work represent both theoretical and experimental investigations of the effects of plastic strain generation in shape memory alloys (SMAs). Based on the results of SMA experimental characterization described in the literature and additional testing described in this work, a new 3D constitutive model is proposed. This phenomenological model captures both the conventional shape memory effects of pseudoelasticity and thermal strain recovery, and additionally considers the initiation and evolution of plastic strains. The model is numerically implemented in a finite element framework using a return mapping algorithm to solve the constitutive equations at each material point. This combination of theory and implementation is unique in its ability to capture the simultaneous evolution of recoverable transformation strains and irrecoverable plastic strains. The consideration of isotropic and kinematic plastic hardening allows the derivation of a theoretical framework capturing the interactions between irrecoverable plastic strain and recoverable strain due to martensitic transformation. Further, the numerical integration of the constitutive equations is formulated such that objectivity is maintained for SMA structures undergoing moderate strains and large displacements. The implemented model has been used to perform 3D analysis of SMA structural components under uniaxial and bending loads, including a case of local buckling behavior. Experimentally validated results considering simultaneous transformation and plasticity in a bending member are provided, illustrating the predictive accuracy of the model and its implementation

  4. The relationship between species richness and aboveground biomass in a primary Pinus kesiya forest of Yunnan, southwestern China.

    Science.gov (United States)

    Li, Shuaifeng; Lang, Xuedong; Liu, Wande; Ou, Guanglong; Xu, Hui; Su, Jianrong

    2018-01-01

    The relationship between biodiversity and biomass is an essential element of the natural ecosystem functioning. Our research aims at assessing the effects of species richness on the aboveground biomass and the ecological driver of this relationship in a primary Pinus kesiya forest. We sampled 112 plots of the primary P. kesiya forests in Yunnan Province. The general linear model and the structural equation model were used to estimate relative effects of multivariate factors among aboveground biomass, species richness and the other explanatory variables, including climate moisture index, soil nutrient regime and stand age. We found a positive linear regression relationship between the species richness and aboveground biomass using ordinary least squares regressions. The species richness and soil nutrient regime had no direct significant effect on aboveground biomass. However, the climate moisture index and stand age had direct effects on aboveground biomass. The climate moisture index could be a better link to mediate the relationship between species richness and aboveground biomass. The species richness affected aboveground biomass which was mediated by the climate moisture index. Stand age had direct and indirect effects on aboveground biomass through the climate moisture index. Our results revealed that climate moisture index had a positive feedback in the relationship between species richness and aboveground biomass, which played an important role in a link between biodiversity maintenance and ecosystem functioning. Meanwhile, climate moisture index not only affected positively on aboveground biomass, but also indirectly through species richness. The information would be helpful in understanding the biodiversity-aboveground biomass relationship of a primary P. kesiya forest and for forest management.

  5. Biomass

    Science.gov (United States)

    Bernard R. Parresol

    2001-01-01

    Biomass, the contraction for biological mass, is the amount of living material provided by a given area or volume of the earth's surface, whether terrestrial or aquatic. Biomass is important for commercial uses (e.g., fuel and fiber) and for national development planning, as well as for scientific studies of ecosystem productivity, energy and nutrient flows, and...

  6. Institute of constitutional revision in the Constitution of the Republic of Albania, comparative view

    Directory of Open Access Journals (Sweden)

    Makbule Çeço

    2014-07-01

    Full Text Available In its very dynamic essence, a democratic society bears the need for continuous reformation and perfection, and that is why the application of reforms represents an inseparable feature for this type of society. The consolidation of the rule of law, the institutional independence, and the cause of justice itself comprise, inter alia, the need for constitutional revision. This study puts forward a theoretical-historical comparative view of the relevant and dynamic issue of the institute of constitutional revision in the framework of the Constitution of the Republic of Albania, as a complex process accompanied by limitations on constitutional revision. The historical evolution of constitutional drafting, modern constitutions, relevant issues, political and social circumstances as well as drafting and adoption procedures, dynamism of constitutions to cope with the course of time achieved by revisions for the purpose of their stability as well as consolidation of the role of constitutions as a factor that facilitates and precedes social development, comprise the pillar of this study addressed in a comparative point of view.

  7. Standing crop and aboveground biomass partitioning of a dwarf mangrove forest in Taylor River Slough, Florida

    Science.gov (United States)

    Coronado-Molina, C.; Day, J.W.; Reyes, E.; Perez, B.C.

    2004-01-01

    The structure and standing crop biomass of a dwarf mangrove forest, located in the salinity transition zone ofTaylor River Slough in the Everglades National Park, were studied. Although the four mangrove species reported for Florida occurred at the study site, dwarf Rhizophora mangle trees dominated the forest. The structural characteristics of the mangrove forest were relatively simple: tree height varied from 0.9 to 1.2 meters, and tree density ranged from 7062 to 23 778 stems haa??1. An allometric relationship was developed to estimate leaf, branch, prop root, and total aboveground biomass of dwarf Rhizophora mangle trees. Total aboveground biomass and their components were best estimated as a power function of the crown area times number of prop roots as an independent variable (Y = B ?? Xa??0.5083). The allometric equation for each tree component was highly significant (pRhizophora mangle contributed 85% of total standing crop biomass. Conocarpus erectus, Laguncularia racemosa, and Avicennia germinans contributed the remaining biomass. Average aboveground biomass allocation was 69% for prop roots, 25% for stem and branches, and 6% for leaves. This aboveground biomass partitioning pattern, which gives a major role to prop roots that have the potential to produce an extensive root system, may be an important biological strategy in response to low phosphorus availability and relatively reduced soils that characterize mangrove forests in South Florida.

  8. A Constitutive Formulation for the Linear Thermoelastic Behavior of Arbitrary Fiber-Reinforced Composites

    Directory of Open Access Journals (Sweden)

    Melek Usal

    2010-01-01

    Full Text Available The linear thermoelastic behavior of a composite material reinforced by two independent and inextensible fiber families has been analyzed theoretically. The composite material is assumed to be anisotropic, compressible, dependent on temperature gradient, and showing linear elastic behavior. Basic principles and axioms of modern continuum mechanics and equations belonging to kinematics and deformation geometries of fibers have provided guidance and have been determining in the process of this study. The matrix material is supposed to be made of elastic material involving an artificial anisotropy due to fibers reinforcing by arbitrary distributions. As a result of thermodynamic constraints, it has been determined that the free energy function is dependent on a symmetric tensor and two vectors whereas the heat flux vector function is dependent on a symmetric tensor and three vectors. The free energy and heat flux vector functions have been represented by a power series expansion, and the type and the number of terms taken into consideration in this series expansion have determined the linearity of the medium. The linear constitutive equations of the stress and heat flux vector are substituted in the Cauchy equation of motion and in the equation of conservation of energy to obtain the field equations.

  9. The biomass

    International Nuclear Information System (INIS)

    Viterbo, J.

    2011-01-01

    Biomass comes mainly from forests and agriculture and is considered as a clean alternative energy that can be valorized as heat, power, bio-fuels and chemical products but its mass production is challenging in terms of adequate technology but also in terms of rethinking the use of lands. Forests can be managed to produce biomass but bio-fuels can also be generated from sea-weeds. Biomass appears very promising but on one hand we have to secure its supplying and assure its economical profitability and on another hand we have to assure a reasonable use of lands and a limited impact on the environment. The contribution of biomass to sustainable development depends on the balance between these 2 ends. (A.C.)

  10. Biomass [updated

    Energy Technology Data Exchange (ETDEWEB)

    Turhollow Jr, Anthony F [ORNL

    2016-01-01

    Biomass resources and conversion technologies are diverse. Substantial biomass resources exist including woody crops, herbaceous perennials and annuals, forest resources, agricultural residues, and algae. Conversion processes available include fermentation, gasification, pyrolysis, anaerobic digestion, combustion, and transesterification. Bioderived products include liquid fuels (e.g. ethanol, biodiesel, and gasoline and diesel substitutes), gases, electricity, biochemical, and wood pellets. At present the major sources of biomass-derived liquid fuels are from first generation biofuels; ethanol from maize and sugar cane (89 billion L in 2013) and biodiesel from vegetable oils and fats (24 billion liters in 2011). For other than traditional uses, policy in the forms of mandates, targets, subsidies, and greenhouse gas emission targets has largely been driving biomass utilization. Second generation biofuels have been slow to take off.

  11. Allometric Equations for Estimating Carbon Stocks in Natural Forest in New Zealand

    Directory of Open Access Journals (Sweden)

    Andrea Brandon

    2012-09-01

    Full Text Available Species-specific and mixed-species volume and above ground biomass allometric equations were developed for 15 indigenous tree species and four tree fern species in New Zealand. A mixed-species tree equation based on breast height diameter (DBH and tree height (H provided acceptable estimates of stem plus branch (>10 cm in diameter over bark volume, which was multiplied by live tree density to estimate dry matter. For dead standing spars, DBH, estimated original height, actual spar height and compatible volume/taper functions provided estimates of dead stem volume, which was multiplied by live tree density and a density modifier based on log decay class from field assessments to estimate dry matter. Live tree density was estimated using ratio estimators. Ratio estimators were based on biomass sample trees, and utilized density data from outerwood basic density surveys which were available for 35 tree species sampled throughout New Zealand. Foliage and branch ( < 10 cm in diameter over bark dry matter were estimated directly from tree DBH. Tree fern above ground dry matter was estimated using allometric equations based on DBH and H. Due to insufficient data, below ground carbon for trees was estimated using the default IPCC root/shoot ratio of 25%, but for tree ferns it was estimated using measured root/shoot ratios which averaged 20%.

  12. Model Persamaan Massa Karbon Akar Pohon dan Root-Shoot Ratio Massa Karbon (Equation Models of Tree Root Carbon Mass and Root-Shoot Carbon Mass Ratio

    Directory of Open Access Journals (Sweden)

    Elias .

    2011-03-01

    Full Text Available The case study was conducted in the area of Acacia mangium plantation at BKPH Parung Panjang, KPH Bogor. The objective of the study was to formulate equation models of tree root carbon mass and root to shoot carbon mass ratio of the plantation. It was found that carbon content in the parts of tree biomass (stems, branches, twigs, leaves, and roots was different, in which the highest and the lowest carbon content was in the main stem of the tree and in the leaves, respectively. The main stem and leaves of tree accounted for 70% of tree biomass. The root-shoot ratio of root biomass to tree biomass above the ground and the root-shoot ratio of root biomass to main stem biomass was 0.1443 and 0.25771, respectively, in which 75% of tree carbon mass was in the main stem and roots of tree. It was also found that the root-shoot ratio of root carbon mass to tree carbon mass above the ground and the root-shoot ratio of root carbon mass to tree main stem carbon mass was 0.1442 and 0.2034, respectively. All allometric equation models of tree root carbon mass of A. mangium have a high goodness-of-fit as indicated by its high adjusted R2.Keywords: Acacia mangium, allometric, root-shoot ratio, biomass, carbon mass

  13. Enhancement of anti-tubercular activity and biomass of fermented food associated Staphylococcus hominis strain MANF2 using Taguchi orthogonal array and Box-Behnken design.

    Science.gov (United States)

    Khusro, Ameer; Aarti, Chirom; Dusthackeer, Azger; Agastian, Paul

    2018-04-14

    The prime focus of the present investigation was to optimize statistically the anti-tubercular activity and biomass of fermented food associated Staphylococcus hominis strain MANF2 using Taguchi orthogonal array (OA) and Box-Behnken design (BBD). The anti-tubercular activity of strain MANF2 was determined against Mycobacterium tuberculosis H37Rv using luciferase reporter phase assay. Among varied media examined, the isolate exhibited impressive anti-tubercular activity with paramount relative light unit reduction of >90% in de Man Rogose Sharpe (MRS) broth. Primarily, the anti-tubercular activity and biomass of strain MANF2 were estimated in MRS broth by optimizing eight diversified parameters using one factor at a time (OFAT) method after working out a series of experiments. The most significant contributing factors selected through OFAT tool were optimized using Taguchi approach with a standard OA layout of L18 (2 2  × 3 6 ). Results demonstrated the significant (P ≤ 0.05) influence of pH, temperature, yeast extract, magnesium sulphate, and glycerol on response variables. These controlled variables were further optimized using BBD matrix at N = 46 by second-order polynomial equation. The fermentation medium of pH 6.5 constituting yeast extract (0.5% w/v), magnesium sulphate (0.1% w/v), and glycerol (1.5% v/v), being further incubated at 30 °C showed enhanced anti-tubercular activity (98.7%) and approximately 4 fold increment in the bacterial biomass yield (8.3 mg/mL) with respect to traditional OFAT method. Three-dimensional response plots of the quadratic model showed interdependent interaction between the significant variables. In conclusion, the present study revealed the first report on the optimization of anti-tubercular activity and biomass of S. hominis via Taguchi OA as well as BBD design, and thus, paved a path for its proficient applications in pharmaceutical industries as dynamic mycobactericidal agent in future. Copyright © 2018

  14. IMPROVING BIOMASS LOGISTICS COST WITHIN AGRONOMIC SUSTAINABILITY CONSTRAINTS AND BIOMASS QUALITY TARGETS

    Energy Technology Data Exchange (ETDEWEB)

    J. Richard Hess; Kevin L. Kenney; Christopher T. Wright; David J. Muth; William Smith

    2012-10-01

    Equipment manufacturers have made rapid improvements in biomass harvesting and handling equipment. These improvements have increased transportation and handling efficiencies due to higher biomass densities and reduced losses. Improvements in grinder efficiencies and capacity have reduced biomass grinding costs. Biomass collection efficiencies (the ratio of biomass collected to the amount available in the field) as high as 75% for crop residues and greater than 90% for perennial energy crops have also been demonstrated. However, as collection rates increase, the fraction of entrained soil in the biomass increases, and high biomass residue removal rates can violate agronomic sustainability limits. Advancements in quantifying multi-factor sustainability limits to increase removal rate as guided by sustainable residue removal plans, and mitigating soil contamination through targeted removal rates based on soil type and residue type/fraction is allowing the use of new high efficiency harvesting equipment and methods. As another consideration, single pass harvesting and other technologies that improve harvesting costs cause biomass storage moisture management challenges, which challenges are further perturbed by annual variability in biomass moisture content. Monitoring, sampling, simulation, and analysis provide basis for moisture, time, and quality relationships in storage, which has allowed the development of moisture tolerant storage systems and best management processes that combine moisture content and time to accommodate baled storage of wet material based upon “shelf-life.” The key to improving biomass supply logistics costs has been developing the associated agronomic sustainability and biomass quality technologies and processes that allow the implementation of equipment engineering solutions.

  15. Energy from biomass: an econometric model for production; Energia de biomassa: um modelo econometrico de producao

    Energy Technology Data Exchange (ETDEWEB)

    Pinho, L A.Z. [Universidade Federal, Rio de Janeiro, RJ (Brazil). Coordenacao dos Programas de Pos-graduacao de Engenharia; Brandt, S A [Vicosa Univ., MG (Brazil); Moro, S; Wong, S [MAPAG, Juiz de Fora, MG (Brazil); Almeida, J M.C. de [Espirito Santo Univ., Vitoria, ES (Brazil)

    1988-12-31

    The study specify a dynamic model of production adjustment for charcoal and fuel-wood energy. This model is then transformed in two equations being its reduced forms. Annual series data (1954-80) covering the county as a whole are used. Desired or equilibrium energy output is expressed as a function of general economic activity and cost of factors of production. The reduced form equations are fitted by OLS. The results are promising and implications for biomass energy management and government incentive policy are developed. 11 refs.

  16. A multiphase constitutive model of reinforced soils accounting for soil-inclusion interaction behaviour

    OpenAIRE

    BENNIS, M; DE BUHAN, P

    2003-01-01

    A two-phase continuum description of reinforced soil structures is proposed in which the soil mass and the reinforcement network are treated as mutually interacting superposed media. The equations governing such a model are developed in the context of elastoplasticity, with special emphasis put on the soil/reinforcement interaction constitutive law. As shown in an illustrative example, such a model paves the way for numerically efficient design methods of reinforced soil structures.

  17. Planning woody biomass logistics for energy production: A strategic decision model

    International Nuclear Information System (INIS)

    Frombo, F.; Robba, M.; Minciardi, R.; Sacile, R.; Rosso, F.

    2009-01-01

    One of the key factors on which the sustainable development of modern society should be based is the possibility to take advantage of renewable energies. Biomass resources are one of the most common and widespread resources in the world. Their use to produce energy has many advantages, such as the reduction of greenhouse emissions. This paper describes a GIS-based Environmental Decision Support System (EDSS) to define planning and management strategies for the optimal logistics for energy production from woody biomass, such as forest biomass, agricultural scraps and industrial and urban untreated wood residues. The EDSS is characterized by three main levels: the GIS, the database, and the optimization. The optimization module is divided in three sub-modules to face different kinds of decision problems: strategic planning, tactical planning, and operational management. The aim of this article is to describe the strategic planning level in detail. The decision variables are represented by plant capacity and harvested biomass in a specific forest parcel for each slope class, while the objective function is the sum of the costs related to plant installation and maintenance, biomass transportation and collection, minus the benefits coming from the energy sales at the current market price, including the renewable energy certificates. Moreover, the optimization problem is structured through a set of parameters and equations that are able to encompass different energy conversion technologies (pyrolysis, gasification or combustion) in the system. A case study on the Liguria Region (Savona Province) is presented and results are discussed. (author)

  18. Biomass Supply and Trade Opportunities of Preprocessed Biomass for Power Generation

    NARCIS (Netherlands)

    Batidzirai, B.; Junginger, M.; Klemm, M.; Schipfer, F.; Thrän, D.

    2016-01-01

    International trade of solid biomass is expected to increase significantly given the global distribution of biomass resources and anticipated expansion of bioenergy deployment in key global power markets. Given the unique characteristics of biomass, its long-distance trade requires optimized

  19. Biomass Feedstocks | Bioenergy | NREL

    Science.gov (United States)

    Feedstocks Biomass Feedstocks Our mission is to enable the coordinated development of biomass generic biomass thermochemical conversion process (over a screened-back map of the United States) showing U.S. Biomass Resources, represented by photos of timber, corn stover, switchgrass, and poplar. All

  20. Terrestrial laser scanning to quantify above-ground biomass of structurally complex coastal wetland vegetation

    Science.gov (United States)

    Owers, Christopher J.; Rogers, Kerrylee; Woodroffe, Colin D.

    2018-05-01

    Above-ground biomass represents a small yet significant contributor to carbon storage in coastal wetlands. Despite this, above-ground biomass is often poorly quantified, particularly in areas where vegetation structure is complex. Traditional methods for providing accurate estimates involve harvesting vegetation to develop mangrove allometric equations and quantify saltmarsh biomass in quadrats. However broad scale application of these methods may not capture structural variability in vegetation resulting in a loss of detail and estimates with considerable uncertainty. Terrestrial laser scanning (TLS) collects high resolution three-dimensional point clouds capable of providing detailed structural morphology of vegetation. This study demonstrates that TLS is a suitable non-destructive method for estimating biomass of structurally complex coastal wetland vegetation. We compare volumetric models, 3-D surface reconstruction and rasterised volume, and point cloud elevation histogram modelling techniques to estimate biomass. Our results show that current volumetric modelling approaches for estimating TLS-derived biomass are comparable to traditional mangrove allometrics and saltmarsh harvesting. However, volumetric modelling approaches oversimplify vegetation structure by under-utilising the large amount of structural information provided by the point cloud. The point cloud elevation histogram model presented in this study, as an alternative to volumetric modelling, utilises all of the information within the point cloud, as opposed to sub-sampling based on specific criteria. This method is simple but highly effective for both mangrove (r2 = 0.95) and saltmarsh (r2 > 0.92) vegetation. Our results provide evidence that application of TLS in coastal wetlands is an effective non-destructive method to accurately quantify biomass for structurally complex vegetation.

  1. Mechanical Behaviour of Materials Volume 1 Micro- and Macroscopic Constitutive Behaviour

    CERN Document Server

    François, Dominique; Zaoui, André

    2012-01-01

    Advances in technology are demanding ever-increasing mastery over the materials being used: the challenge is to gain a better understanding of their behaviour, and more particularly of the relations between their microstructure and their macroscopic properties.   This work, of which this is the first volume, aims to provide the means by which this challenge may be met. Starting from the mechanics of deformation, it develops the laws governing macroscopic behaviour – expressed as the constitutive equations – always taking account of the physical phenomena which underlie rheological behaviour. The most recent developments are presented, in particular those concerning heterogeneous materials such as metallic alloys, polymers and composites. Each chapter is devoted to one of the major classes of material behaviour.   As the subtitles indicate, Volume 1 deals with micro- and macroscopic constitutive behaviour and Volume 2 with damage and fracture mechanics. A third volume will be devoted to exercises and the...

  2. A fractal derivative constitutive model for three stages in granite creep

    Directory of Open Access Journals (Sweden)

    R. Wang

    Full Text Available In this paper, by replacing the Newtonian dashpot with the fractal dashpot and considering damage effect, a new constitutive model is proposed in terms of time fractal derivative to describe the full creep regions of granite. The analytic solutions of the fractal derivative creep constitutive equation are derived via scaling transform. The conventional triaxial compression creep tests are performed on MTS 815 rock mechanics test system to verify the efficiency of the new model. The granite specimen is taken from Beishan site, the most potential area for the China’s high-level radioactive waste repository. It is shown that the proposed fractal model can characterize the creep behavior of granite especially in accelerating stage which the classical models cannot predict. The parametric sensitivity analysis is also conducted to investigate the effects of model parameters on the creep strain of granite. Keywords: Beishan granite, Fractal derivative, Damage evolution, Scaling transformation

  3. Energy from biomass. Teaching material; Energie aus Biomasse. Ein Lehrmaterial

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2002-04-01

    The textbook discusses the available options for power and heat generation from biomass as well as the limits of biomass-based power supply. The main obstacle apart from the high cost is a lack of knowledge, which the book intends to remedy. It addresses students of agriculture, forestry, environmental engineering, heating systems engineering and apprentice chimney sweepers, but it will also be useful to all other interested readers. [German] Biomasse kann aufgrund seiner vielfaeltigen Erscheinungs- und Umwandlungsformen sowohl als Brennstoff zur Waerme- und Stromgewinnung oder als Treibstoff eingesetzt werden. Die energetische Nutzung von Biomasse birgt zudem nicht zu verachtende Vorteile. Zum einen wegen des Beitrags zum Klimaschutz aufgrund der CO{sub 2}-Neutralitaet oder einfach, weil Biomasse immer wieder nachwaechst und von fossilen Ressourcen unabhaengig macht. All den bisher erschlossenen Moeglichkeiten der energetischen Nutzung von Biomasse moechte dieses Lehrbuch Rechnung tragen. Es zeigt aber auch die Grenzen auf, die mit der Energieversorgung durch Bioenergie einhergehen. Hohe Kosten und ein erhebliches Informationsdefizit behinderten bisher eine verstaerkte Nutzung dieses Energietraeges. Letzterem soll dieses Lehrbuch entgegenwirken. Das vorliegende Lehrbuch wurde fuer die Aus- und Weiterbildung erstellt. Es richtet sich vor allem an angehende Land- und Forstwirte, Umwelttechniker, Heizungsbauer und Schornsteinfeger, ist aber auch fuer all diejenigen interessant, die das Thema ''Energie aus Biomasse'' verstehen und ueberblicken moechten. (orig.)

  4. The Possibility of Vice-Presidents’ Authority Arrangement in the 1945 Constitution through Constitutional Amendment

    Directory of Open Access Journals (Sweden)

    Fajar L. Suroso

    2016-04-01

    Full Text Available The debate over the vice-presidents’ authority reappeared in the administration of President Jokowi after the “authority expansion of the Chief of Presidency Staff” and the case of “Rizal Ramli vs Jusuf Kalla”. This article is intended to provide arguments for the idea of some parties to organize more explicit and detailed the authority of vice-president in the 1945 Constitution. The idea arises from the absence of further arrangement on the authority of vice-president in the 1945 Constitution. This article is systematized into 3 (three sub-theme; 1 the arrangement of the vice-presidents’ authority in the constitution for several countries; 2 The authority of the vice-president according to the 1945 Constitution, and 3 New resultant and the possibility of 1945 Constitution amendment. The result revealed a number of interesting things; 1 the constitutions of other countries do not specify the authority of the vice-president and put the vice-president as a “spare tire” when the president is absent; 2 no new resultant about the position and authority of the vice-president so that theoretically is not reason enough to regulate in detail the authority of the vice-president through the 1945 Constitution amendment; 3 arrangement in detail in the authority of vice-president in the 1945 Constitution holds the potential to confuse the presidential system design as the 1945 Constitution. Therefore, the possibility of vice-presidents’ authority arrangement in the 1945 Constitution through amendment is very small, both in terms of momentum and the substance of issues.

  5. Biomass cogeneration: A business assessment

    Science.gov (United States)

    Skelton, J. C.

    1981-11-01

    The biomass cogeneration was reviewed. The business assessment is based in part on discussions with key officials from firms that have adopted biomass cogeneration systems and from organizations such as utilities, state and federal agencies, and banks directly involved in a biomass cogeneration project. The guide is organized into five chapters: biomass cogeneration systems, biomass cogeneration business considerations, biomass cogeneration economics, biomass cogeneration project planning, and case studies.

  6. Constitutional Fundamentals of Conscription and Some Aspects of the Ordinary Legal Regulation of Constitutionality

    Directory of Open Access Journals (Sweden)

    Kenstavičienė Kristina

    2015-12-01

    Full Text Available Article 139 of the Constitution of the Republic of Lithuania is one of the constitutional fundamentals of state defense and stipulates the defense of the state as the right of citizens on the one hand and the duty on the other. This article of the Constitution gives the legislative power the right of discretion to detail by law the order of the implementation of citizens’ duty to perform military or alternative country defense service. Due to the reorganization of the armed forces into a professional and volunteer army, the issue of some ordinary regulation rules concerning the constitutionality of nationwide conscription, though at present suspended but not abolished, is becoming urgent. Though the Constitutional Court of the Republic of Lithuania presented their ruling on the constitutionality of the suspension of military conscription, it does not mean that all problems related to conscription have been settled. The aim of this article is to analyze the constitutional basis of nationwide conscription as well as the constitutionality of some ordinary regulation provisions related to nationwide conscription. Therefore, the issue to be analyzed is whether nationwide conscription, if it were to be implemented, complies with the constitutional principles of human equality and military justice1. Consequently, the question is posed how the constitutional objective of ensuring the defense of the state determines conscription. Because of the growing employment of the army abroad, yet the dwindling demand for conscripts, it should be explored whether the suspension of the nationwide conscription as a part of the defense reform is further feasible in order to guarantee the defense of the state. In answering the raised questions, the author will analyze the abundant and long-lasting constitutional doctrine of Germany which provides clarifications of the Basic Law, as the legal act of the establishing power, which can doubtless be of assistance in

  7. Biomass Demand-Resources Value Targeting

    International Nuclear Information System (INIS)

    Lim, Chun Hsion; Lam, Hon Loong

    2014-01-01

    Highlights: • Introduce DRVT supply chain modelling approach to consider underutilised biomass. • Advantages of the novel DRVT biomass supply chain approach. • A case study is presented to demonstrate the improvement of the system. - Abstract: With the global awareness towards sustainability, biomass industry becomes one of the main focuses in the search of alternative renewable resources for energy and downstream product. However, the efficiency of the biomass management, especially in supply chain is still questionable. Even though many researches and integrations of supply chain network have been conducted, less has considered underutilised biomass. This leads to the ignorance of potential value in particular biomass species. A new Demand-Resources Value Targeting (DRVT) approach is introduced in this study to investigate the value of each biomass available in order to fully utilise the biomass in respective applications. With systematic biomass value classification, integration of supply chain based on biomass value from biomass resources-to-downstream product can be developed. DRVT model allows better understanding of biomass and their potential downstream application. A simple demonstration of DRVT approach is conducted based on biomass resources in Malaysia

  8. Numerical studies of the influence of food ingestion on phytoplankton and zooplankton biomasses

    Directory of Open Access Journals (Sweden)

    Lidia Dzierzbicka-G³owacka

    2002-03-01

    Full Text Available This paper presents the numerical simulations of the influence of food ingestion by a herbivorous copepod on phytoplankton and zooplankton biomasses (PZB in the sea. The numerical studies were carried out using the phytoplankton-zooplankton-nutrient-detritus PhyZooNuDe biological upper layer model. This takes account both of fully developed primary production and regeneration mechanisms and of daily migration of zooplankton. In this model the zooplankton is treated not as a 'biomass' but as organisms having definite patterns of growth, reproduction and mortality. Assuming also that {Zoop} is composed ofi cohorts of copepods with weights Wi and numbers Zi, then {Zoop} = WiZi. The PhyZooNuDe model consists of three coupled, partial second-order differential equations of the diffusion type for phytoplankton, zooplankton and nutrients, and one ordinary first-order differential equation for the benthic detritus pool, together with initial and boundary conditions. The calculations were made during 90 days (April, May and June for the study area P1 (Gdansk Deep in an area 0z<=20 m with a vertical space step of 0.1 m and a time step of 300 s. The simulation given here demonstrated the importance of food ingestion by zooplankton in that it can alter the nature of the interactions of plants and herbivores. The analysis of these numerical studies indicate that the maximal ingestion rate and the half-saturation constant for grazing strongly affect the magnitude of the spring bloom and the cyanobacterial bloom, and also the total zooplankton biomass.

  9. Rheology of concentrated biomass

    Science.gov (United States)

    J.R. Samaniuk; J. Wang; T.W. Root; C.T. Scott; D.J. Klingenberg

    2011-01-01

    Economic processing of lignocellulosic biomass requires handling the biomass at high solids concentration. This creates challenges because concentrated biomass behaves as a Bingham-like material with large yield stresses. Here we employ torque rheometry to measure the rheological properties of concentrated lignocellulosic biomass (corn stover). Yield stresses obtained...

  10. Hypersonic expansion of the Fokker--Planck equation

    International Nuclear Information System (INIS)

    Fernandez-Feria, R.

    1989-01-01

    A systematic study of the hypersonic limit of a heavy species diluted in a much lighter gas is made via the Fokker--Planck equation governing its velocity distribution function. In particular, two different hypersonic expansions of the Fokker--Planck equation are considered, differing from each other in the momentum equation of the heavy gas used as the basis of the expansion: in the first of them, the pressure tensor is neglected in that equation while, in the second expansion, the pressure tensor term is retained. The expansions are valid when the light gas Mach number is O(1) or larger and the difference between the mean velocities of light and heavy components is small compared to the light gas thermal speed. They can be applied away from regions where the spatial gradient of the distribution function is very large, but it is not restricted with respect to the temporal derivative of the distribution function. The hydrodynamic equations corresponding to the lowest order of both expansions constitute two different hypersonic closures of the moment equations. For the subsequent orders in the expansions, closed sets of moment equations (hydrodynamic equations) are given. Special emphasis is made on the order of magnitude of the errors of the lowest-order hydrodynamic quantities. It is shown that if the heat flux vanishes initially, these errors are smaller than one might have expected from the ordinary scaling of the hypersonic closure. Also it is found that the normal solution of both expansions is a Gaussian distribution at the lowest order

  11. Constitutive cellulase production from glucose using the recombinant Trichoderma reesei strain overexpressing an artificial transcription activator.

    Science.gov (United States)

    Zhang, Xiaoyue; Li, Yonghao; Zhao, Xinqing; Bai, Fengwu

    2017-01-01

    The high cost of cellulase production presents biggest challenge in biomass deconstruction. Cellulase production by Trichoderma reesei using low cost carbon source is of great interest. In this study, an artificial transcription activator containing the Cre1 binding domain linked to the Xyr1 effector and binding domains was designed and constitutively overexpressed in T. reesei RUT C30. The recombinant strain T. reesei zxy-2 displayed constitutive cellulase production using glucose as a sole carbon source, and the production titer was 12.75-fold of that observed with T. reesei RUT C30 in shake flask culture. Moreover, FPase and xylanase titers of 2.63 and 108.72IU/mL, respectively, were achieved using glucose as sole carbon source within 48h in a 7-L fermenter by batch fermentation using T. reesei zxy-2. The crude enzyme obtained was used to hydrolyze alkali pretreated corn stover, and a high glucose yield of 99.18% was achieved. Copyright © 2016. Published by Elsevier Ltd.

  12. Constitutional tolerance to heavy metals of a fiber crop, ramie (Boehmeria nivea), and its potential usage

    Energy Technology Data Exchange (ETDEWEB)

    Yang, B.; Zhou, M.; Shu, W.S.; Lan, C.Y. [State Key Laboratory of Biocontrol, and School of Life Sciences, Sun Yat-sen (Zhongshan) University, Guangzhou 510275 (China); Ye, Z.H., E-mail: lssyzhh@mail.sysu.edu.c [State Key Laboratory of Biocontrol, and School of Life Sciences, Sun Yat-sen (Zhongshan) University, Guangzhou 510275 (China); Qiu, R.L. [Guangdong Provincial Key Lab of Environmental Pollution Control and Remediation Technology, and School of Sciences and Engineering, Sun Yat-sen (Zhongshan) University, Guangzhou 510275 (China); Jie, Y.C. [Institute of Bast Fiber Crops, Chinese Academy of Agricultural Sciences, Changsha 410205 (China); Cui, G.X. [Ramie Research Institute, Hunan Agricultural University, Changsha 410128 (China); Wong, M.H., E-mail: mhwong@hkbu.edu.h [Croucher Institute for Environmental Sciences, and Department of Biology, Hong Kong Baptist University, Kowloon Tong (Hong Kong)

    2010-02-15

    It is observed that ramie (Boehmeria nivea), an economic fiber crop, can establish and colonize metal-contaminated sites in China. Metal tolerance and accumulation by ramie originating from 13 metal-contaminated and 4 'clean' sites in China were compared under field and hydroponic conditions. All selected populations and germplasms displayed good growth performance under diverse metal-contaminated habitats; while growth responses, metal accumulation and tolerance were similar among the 8 populations and 2 germplasms when exposed to solutions containing elevated As, Cd, Pb, or Zn in the laboratory. These revealed that ramie possesses a certain degree of constitutional metal tolerance. To our knowledge, this is the first report of constitutional metal tolerance possessed by a fiber crop. Ramie can be considered as a good candidate for both fiber production and phytoremediation of sites contaminated by multi-metals, as it accumulates relative low metal concentrations, but possesses both high biomass and high economic value. - Ramie possesses economic and environmental values in phytoremediation

  13. Thermal characteristics of various biomass fuels in a small-scale biomass combustor

    International Nuclear Information System (INIS)

    Al-Shemmeri, T.T.; Yedla, R.; Wardle, D.

    2015-01-01

    Biomass combustion is a mature and reliable technology, which has been used for heating and cooking. In the UK, biomass currently qualifies for financial incentives such as the Renewable Heat Incentive (RHI). Therefore, it is vital to select the right type of fuel for a small-scale combustor to address different types of heat energy needs. In this paper, the authors attempt to investigate the performance of a small-scale biomass combustor for heating, and the impact of burning different biomass fuels on useful output energy from the combustor. The test results of moisture content, calorific value and combustion products of various biomass samples were presented. Results from this study are in general agreement with published data as far as the calorific values and moisture contents are concerned. Six commonly available biomass fuels were tested in a small-scale combustion system, and the factors that affect the performance of the system were analysed. In addition, the study has extended to examine the magnitude and proportion of useful heat, dissipated by convection and radiation while burning different biomass fuels in the small-scale combustor. It is concluded that some crucial factors have to be carefully considered before selecting biomass fuels for any particular heating application. - Highlights: • Six biomass materials combustion performance in a small combustor was examined. • Fuel combustion rate and amount of heat release has varied between materials. • Heat release by radiation, convection and flue gasses varied between materials. • Study helps engineers and users of biomass systems to select right materials

  14. Ill-posedness of Dynamic Equations of Compressible Granular Flow

    Science.gov (United States)

    Shearer, Michael; Gray, Nico

    2017-11-01

    We introduce models for 2-dimensional time-dependent compressible flow of granular materials and suspensions, based on the rheology of Pouliquen and Forterre. The models include density dependence through a constitutive equation in which the density or volume fraction of solid particles with material density ρ* is taken as a function of an inertial number I: ρ = ρ * Φ(I), in which Φ(I) is a decreasing function of I. This modelling has different implications from models relying on critical state soil mechanics, in which ρ is treated as a variable in the equations, contributing to a flow rule. The analysis of the system of equations builds on recent work of Barker et al in the incompressible case. The main result is the identification of a criterion for well-posedness of the equations. We additionally analyze a modification that applies to suspensions, for which the rheology takes a different form and the inertial number reflects the role of the fluid viscosity.

  15. Characterization of hydrodynamics and solids mixing in fluidized beds involving biomass

    Science.gov (United States)

    Fotovat, Farzam

    This thesis focuses on the characterization of hydrodynamics and mixing phenomena in fluidized beds containing mixtures of sand and irregular biomass particles. The first objective of this study is understanding the effect of the large biomass particles on the bubbling characteristics and gas distribution pattern of sand fluidized beds. The second objective is the characterization of mixing/segregation of biomass and sand particles under fluidization conditions. A variety of experimental techniques are employed to study the behavior of two constituting phases of a fluidized bed, i.e., dilute (bubble) and dense (emulsion) phases. Exploring the characteristic fluidization velocities of sand-biomass mixtures unveils that the onset of bubbling in these systems occurs at a higher gas velocity compared to that of the initial fluidization velocity (Uif). The initial bubbling velocity (Uib), the final fluidization velocity ( Uff), and the transition gas velocity from bubbling to turbulent regime (Uc) rise by increasing the fraction of biomass in the mixture. Statistical analysis of the pressure signal at top of the bed reveals that increasing the biomass load hinders the evolution of bubbles at a low gas velocity (Uactive biomass particle is tracked for a long period of time and its instantaneous position is recorded. The acquired data is then processed to achieve the time-averaged concentration profile of biomass particles. This profile represents the segregation of biomass particles, which tend to accumulate in the upper levels of the bed. Changes in the fraction of biomass with increasing gas velocity are inferred from the local changes of the time-averaged pressure drop values at the top of the bed. To determine the parameters affecting the movement and segregation of biomass particles, their circulatory motion is also scrutinized using the RPT data. The circulation of biomass is impeded when the load of biomass rises at U=0.36 m/s, resulting in a more pronounced

  16. GENERAL EQUATIONS OF CARBONIZATION OF EUCALYPTUS SPP KINETIC MECHANISMS

    Directory of Open Access Journals (Sweden)

    Túlio Jardim Raad

    2006-06-01

    Full Text Available In the present work, a set of general equations related to kinetic mechanism of wood compound carbonization: hemicelluloses, cellulose and lignin was obtained by Avrami-Eroffev and Arrhenius equations and Thermogravimetry of Eucalyptus cloeziana, Eucalyptus camaldulensis, Corymbia citriodora, Eucalyptus urophylla and Eucalyptus grandis samples, TG-Isothermal and TG-Dynamic. The different thermal stabilities and decomposition temperature bands of those species compounds were applied as strategy to obtain the kinetic parameters: activation energy, exponential factor and reaction order. The kinetic model developed was validated by thermogravimetric curves from carbonization of others biomass such as coconut. The kinetic parameters found were - Hemicelluloses: E=98,6 kJmol, A=3,5x106s-1 n=1,0; - Cellulose: E=182,2 kJmol, A=1,2x1013s-1 n=1,5; - Lignin: E=46,6 kJmol, A=2,01s-1 n=0,41. The set of equations can be implemented in a mathematical model of wood carbonization simulation (with heat and mass transfer equations with the aim of optimizing the control and charcoal process used to produce pig iron.

  17. Biomass burning in Africa: As assessment of annually burned biomass

    International Nuclear Information System (INIS)

    Delmas, R.A.; Loudjani, P.; Podaire, A.; Menaut, J.C.

    1991-01-01

    It is now established that biomass burning is the dominant phenomenon that controls the atmospheric chemistry in the tropics. Africa is certainly the continent where biomass burning under various aspects and processes is the greatest. Three different types of burnings have to be considered-bush fires in savanna zones which mainly affect herbaceous flora, forest fires due to forestation for shifting agriculture or colonization of new lands, and the use of wood as fuel. The net release of carbon resulting from deforestation is assumed to be responsible for about 20% of the CO 2 increase in the atmosphere because the burning of forests corresponds to a destorage of carbon from the biospheric reservoir. The amount of reactive of greenhouse gases emitted by biomass burning is directly proportional, through individual emission factors, to the biomass actually burned. This chapter evaluates the biomass annually burned on the African continent as a result of the three main burning processes previously mentioned

  18. Diffusion with space memory modelled with distributed order space fractional differential equations

    Directory of Open Access Journals (Sweden)

    M. Caputo

    2003-06-01

    Full Text Available Distributed order fractional differential equations (Caputo, 1995, 2001; Bagley and Torvik, 2000a,b were fi rst used in the time domain; they are here considered in the space domain and introduced in the constitutive equation of diffusion. The solution of the classic problems are obtained, with closed form formulae. In general, the Green functions act as low pass fi lters in the frequency domain. The major difference with the case when a single space fractional derivative is present in the constitutive equations of diffusion (Caputo and Plastino, 2002 is that the solutions found here are potentially more fl exible to represent more complex media (Caputo, 2001a. The difference between the space memory medium and that with the time memory is that the former is more fl exible to represent local phenomena while the latter is more fl exible to represent variations in space. Concerning the boundary value problem, the difference with the solution of the classic diffusion medium, in the case when a constant boundary pressure is assigned and in the medium the pressure is initially nil, is that one also needs to assign the fi rst order space derivative at the boundary.

  19. Biomass is the main driver of changes in ecosystem process rates during tropical forest succession.

    Science.gov (United States)

    Lohbeck, Madelon; Poorter, Lourens; Martínez-Ramos, Miguel; Bongers, Frans

    2015-05-01

    Over half of the world's forests are disturbed, and the rate at which ecosystem processes recover after disturbance is important for the services these forests can provide. We analyze the drivers' underlying changes in rates of key ecosystem processes (biomass productivity, litter productivity, actual litter decomposition, and potential litter decomposition) during secondary succession after shifting cultivation in wet tropical forest of Mexico. We test the importance of three alternative drivers of ecosystem processes: vegetation biomass (vegetation quantity hypothesis), community-weighted trait mean (mass ratio hypothesis), and functional diversity (niche complementarity hypothesis) using structural equation modeling. This allows us to infer the relative importance of different mechanisms underlying ecosystem process recovery. Ecosystem process rates changed during succession, and the strongest driver was aboveground biomass for each of the processes. Productivity of aboveground stem biomass and leaf litter as well as actual litter decomposition increased with initial standing vegetation biomass, whereas potential litter decomposition decreased with standing biomass. Additionally, biomass productivity was positively affected by community-weighted mean of specific leaf area, and potential decomposition was positively affected by functional divergence, and negatively by community-weighted mean of leaf dry matter content. Our empirical results show that functional diversity and community-weighted means are of secondary importance for explaining changes in ecosystem process rates during tropical forest succession. Instead, simply, the amount of vegetation in a site is the major driver of changes, perhaps because there is a steep biomass buildup during succession that overrides more subtle effects of community functional properties on ecosystem processes. We recommend future studies in the field of biodiversity and ecosystem functioning to separate the effects of

  20. Self-Consistent Sources Extensions of Modified Differential-Difference KP Equation

    Science.gov (United States)

    Gegenhasi; Li, Ya-Qian; Zhang, Duo-Duo

    2018-04-01

    In this paper, we investigate a modified differential-difference KP equation which is shown to have a continuum limit into the mKP equation. It is also shown that the solution of the modified differential-difference KP equation is related to the solution of the differential-difference KP equation through a Miura transformation. We first present the Grammian solution to the modified differential-difference KP equation, and then produce a coupled modified differential-difference KP system by applying the source generation procedure. The explicit N-soliton solution of the resulting coupled modified differential-difference system is expressed in compact forms by using the Grammian determinant and Casorati determinant. We also construct and solve another form of the self-consistent sources extension of the modified differential-difference KP equation, which constitutes a Bäcklund transformation for the differential-difference KP equation with self-consistent sources. Supported by the National Natural Science Foundation of China under Grant Nos. 11601247 and 11605096, the Natural Science Foundation of Inner Mongolia Autonomous Region under Grant Nos. 2016MS0115 and 2015MS0116 and the Innovation Fund Programme of Inner Mongolia University No. 20161115

  1. Uncertainty of Forest Biomass Estimates in North Temperate Forests Due to Allometry: Implications for Remote Sensing

    Directory of Open Access Journals (Sweden)

    Razi Ahmed

    2013-06-01

    Full Text Available Estimates of above ground biomass density in forests are crucial for refining global climate models and understanding climate change. Although data from field studies can be aggregated to estimate carbon stocks on global scales, the sparsity of such field data, temporal heterogeneity and methodological variations introduce large errors. Remote sensing measurements from spaceborne sensors are a realistic alternative for global carbon accounting; however, the uncertainty of such measurements is not well known and remains an active area of research. This article describes an effort to collect field data at the Harvard and Howland Forest sites, set in the temperate forests of the Northeastern United States in an attempt to establish ground truth forest biomass for calibration of remote sensing measurements. We present an assessment of the quality of ground truth biomass estimates derived from three different sets of diameter-based allometric equations over the Harvard and Howland Forests to establish the contribution of errors in ground truth data to the error in biomass estimates from remote sensing measurements.

  2. Growing stock and woody biomass assessment in Asola-Bhatti Wildlife Sanctuary, Delhi, India.

    Science.gov (United States)

    Kushwaha, S P S; Nandy, S; Gupta, Mohini

    2014-09-01

    Biomass is an important entity to understand the capacity of an ecosystem to sequester and accumulate carbon over time. The present study, done in collaboration with the Delhi Forest Department, focused on the estimation of growing stock and the woody biomass in the so-called lungs of Delhi--the Asola-Bhatti Wildlife Sanctuary in northern Aravalli hills. The satellite-derived vegetation strata were field-inventoried using stratified random sampling procedure. Growing stock was calculated for the individual sample plots using field data and species-specific volume equations. Biomass was estimated from the growing stock and the specific gravity of the wood. Among the four vegetation types, viz. Prosopis juliflora, Anogeissus pendula, forest plantation and the scrub, the P. juliflora was found to be the dominant vegetation in the area, covering 23.43 km(2) of the total area. The study revealed that P. juliflora forest with moderate density had the highest (10.7 m(3)/ha) while A. pendula forest with moderate density had the lowest (3.6 m(3)/ha) mean volume. The mean woody biomass was also found to be maximum in P. juliflora forest with moderate density (10.3 t/ha) and lowest in A. pendula forest with moderate density (3.48 t/ha). The total growing stock was estimated to be 20,772.95 m(3) while total biomass worked out to be 19,366.83 t. A strong correlation was noticed between the normalized difference vegetation index (NDVI) and the growing stock (R(2) = 0.84)/biomass (R(2) = 0.88). The study demonstrated that growing stock and the biomass of the woody vegetation in Asola-Bhatti Wildlife Sanctuary could be estimated with high accuracy using optical remote sensing data.

  3. 78 FR 57777 - Constitution Day and Citizenship Day, Constitution Week, 2013

    Science.gov (United States)

    2013-09-19

    ... strength of our common ideals. In a document that has endured for more than two and a quarter centuries, the Framers put forth their vision for a more perfect Union. Our Constitution was signed on September... citizenship, recognize the enduring strength of our Constitution, and reaffirm our commitment to the rights...

  4. The equations icons of knowledge

    CERN Document Server

    Bais, Sander

    2005-01-01

    For thousands of years mankind has tried to understand nature. Exploring the world on all scales with instruments of ever more ingenuity, we have been able to unravel some of the great mysteries that surround us. While collecting an overwhelming multitude of observational facts, we discovered fundamental laws that govern the structure and evolution of physical reality. We know that nature speaks to us in the language of mathematics. In this language most of our basic understanding of the physical world can be expressed in an unambiguous and concise way. The most artificial language turns out to be the most natural of all. The laws of nature correspond to equations. These equations are the icons of knowledge that mark crucial turning points in our thinking about the world we happen to live in. They form the symbolic representation of most of what we know, and as such constitute an important and robust part of our culture.

  5. Change of position of constitutional judiciary

    Directory of Open Access Journals (Sweden)

    Orlović Slobodan P.

    2013-01-01

    Full Text Available Constitutional judiciary is the youngest branch of authority in the horizontal level of state power. Constitutional judiciary has, during its existence - during two centuries as an ordinary court and during one century as a special authority, changed its position, role and importance. Those characteristics of constitutional judiciary had an increasing way - the position became better, in political and law sense, its role has expanded and the importance has increased. Today, constitutional judiciary is an inevitable subject of constitutional regimes in huge number of states (between them are almost all federations but, in the same time, constitutional judiciary is an authority which is at least limited by the constitution. The constitution is "soft" to the constitutional judiciary because the judiciary interpreted the constitution in accordance to its political and law attitudes, hidden by the guise of protection. Different separation of power, a rise of executive power, requests for better protections of fundamental human rights, a changed role of state and executive power, altogether, have influenced to change of position of constitutional judiciary.

  6. Contested constitutions: Legitimacy of constitution-making and constitutional conflict in Central Europe

    NARCIS (Netherlands)

    de Raadt, J.B.

    2009-01-01

    What were the effects of constitution-making procedures on the acceptance of the new "rules of the political game" in postcommunist Central Europe? This article sets out to scrutinise the increasingly popular claim among politicians and scholars of democratisation that inclusiveness and popular

  7. Trichoderma Biofertilizer Links to Altered Soil Chemistry, Altered Microbial Communities, and Improved Grassland Biomass

    Directory of Open Access Journals (Sweden)

    Fengge Zhang

    2018-04-01

    Full Text Available In grasslands, forage and livestock production results in soil nutrient deficits as grasslands typically receive no nutrient inputs, leading to a loss of grassland biomass. The application of mature compost has been shown to effectively increase grassland nutrient availability. However, research on fertilization regime influence and potential microbial ecological regulation mechanisms are rarely conducted in grassland soil. We conducted a two-year experiment in meadow steppe grasslands, focusing on above- and belowground consequences of organic or Trichoderma biofertilizer applications and potential soil microbial ecological mechanisms underlying soil chemistry and microbial community responses. Grassland biomass significantly (p = 0.019 increased following amendment with 9,000 kg ha−1 of Trichoderma biofertilizer (composted cattle manure + inoculum compared with other assessed organic or biofertilizer rates, except for BOF3000 (fertilized with 3,000 kg ha−1 biofertilizer. This rate of Trichoderma biofertilizer treatment increased soil antifungal compounds that may suppress pathogenic fungi, potentially partially responsible for improved grassland biomass. Nonmetric multidimensional scaling (NMDS revealed soil chemistry and fungal communities were all separated by different fertilization regime. Trichoderma biofertilizer (9,000 kg ha−1 increased relative abundances of Archaeorhizomyces and Trichoderma while decreasing Ophiosphaerella. Trichoderma can improve grassland biomass, while Ophiosphaerella has the opposite effect as it may secrete metabolites causing grass necrosis. Correlations between soil properties and microbial genera showed plant-available phosphorus may influence grassland biomass by increasing Archaeorhizomyces and Trichoderma while reducing Ophiosphaerella. According to our structural equation modeling (SEM, Trichoderma abundance was the primary contributor to aboveground grassland biomass. Our results suggest Trichoderma

  8. Trichoderma Biofertilizer Links to Altered Soil Chemistry, Altered Microbial Communities, and Improved Grassland Biomass.

    Science.gov (United States)

    Zhang, Fengge; Huo, Yunqian; Cobb, Adam B; Luo, Gongwen; Zhou, Jiqiong; Yang, Gaowen; Wilson, Gail W T; Zhang, Yingjun

    2018-01-01

    In grasslands, forage and livestock production results in soil nutrient deficits as grasslands typically receive no nutrient inputs, leading to a loss of grassland biomass. The application of mature compost has been shown to effectively increase grassland nutrient availability. However, research on fertilization regime influence and potential microbial ecological regulation mechanisms are rarely conducted in grassland soil. We conducted a two-year experiment in meadow steppe grasslands, focusing on above- and belowground consequences of organic or Trichoderma biofertilizer applications and potential soil microbial ecological mechanisms underlying soil chemistry and microbial community responses. Grassland biomass significantly ( p = 0.019) increased following amendment with 9,000 kg ha -1 of Trichoderma biofertilizer (composted cattle manure + inoculum) compared with other assessed organic or biofertilizer rates, except for BOF3000 (fertilized with 3,000 kg ha -1 biofertilizer). This rate of Trichoderma biofertilizer treatment increased soil antifungal compounds that may suppress pathogenic fungi, potentially partially responsible for improved grassland biomass. Nonmetric multidimensional scaling (NMDS) revealed soil chemistry and fungal communities were all separated by different fertilization regime. Trichoderma biofertilizer (9,000 kg ha -1 ) increased relative abundances of Archaeorhizomyces and Trichoderma while decreasing Ophiosphaerella . Trichoderma can improve grassland biomass, while Ophiosphaerella has the opposite effect as it may secrete metabolites causing grass necrosis. Correlations between soil properties and microbial genera showed plant-available phosphorus may influence grassland biomass by increasing Archaeorhizomyces and Trichoderma while reducing Ophiosphaerella . According to our structural equation modeling (SEM), Trichoderma abundance was the primary contributor to aboveground grassland biomass. Our results suggest Trichoderma

  9. Constitutional Referendums:A Theoretical Enquiry

    OpenAIRE

    Tierney, Stephen

    2009-01-01

    In recent decades the use of referendums to settle major constitutional questions has increased dramatically. Addressing this phenomenon as a case study in the relationship between democracy and constitutional sovereignty, this article has two aims.The first is to argue that these constitutional referendums are categorically different from ordinary, legislative referendums, and that this has important implications for theories of constitutional sovereignty. Secondly, the article suggests that...

  10. Shock-wave structure based on the Navier-Stokes-Fourier equations

    Science.gov (United States)

    Uribe, F. J.; Velasco, R. M.

    2018-04-01

    We use the Navier-Stokes-Fourier constitutive equations to study plane shock waves in dilute gases. It is shown that the experimental information on the normalized density profiles can be fit by using the so-called soft sphere model, in which the viscosity and thermal conductivity are proportional to a power of the temperature.

  11. A constitutive rheological model for agglomerating blood derived from nonequilibrium thermodynamics

    Science.gov (United States)

    Tsimouri, Ioanna Ch.; Stephanou, Pavlos S.; Mavrantzas, Vlasis G.

    2018-03-01

    Red blood cells tend to aggregate in the presence of plasma proteins, forming structures known as rouleaux. Here, we derive a constitutive rheological model for human blood which accounts for the formation and dissociation of rouleaux using the generalized bracket formulation of nonequilibrium thermodynamics. Similar to the model derived by Owens and co-workers ["A non-homogeneous constitutive model for human blood. Part 1. Model derivation and steady flow," J. Fluid Mech. 617, 327-354 (2008)] through polymer network theory, each rouleau in our model is represented as a dumbbell; the corresponding structural variable is the conformation tensor of the dumbbell. The kinetics of rouleau formation and dissociation is treated as in the work of Germann et al. ["Nonequilibrium thermodynamic modeling of the structure and rheology of concentrated wormlike micellar solutions," J. Non-Newton. Fluid Mech. 196, 51-57 (2013)] by assuming a set of reversible reactions, each characterized by a forward and a reverse rate constant. The final set of evolution equations for the microstructure of each rouleau and the expression for the stress tensor turn out to be very similar to those of Owens and co-workers. However, by explicitly considering a mechanism for the formation and breakage of rouleaux, our model further provides expressions for the aggregation and disaggregation rates appearing in the final transport equations, which in the kinetic theory-based network model of Owens were absent and had to be specified separately. Despite this, the two models are found to provide similar descriptions of experimental data on the size distribution of rouleaux.

  12. Model Research of Gas Emissions From Lignite and Biomass Co-Combustion in a Large Scale CFB Boiler

    Directory of Open Access Journals (Sweden)

    Krzywański Jarosław

    2014-06-01

    Full Text Available The paper is focused on the idea of a combustion modelling of a large-scale circulating fluidised bed boiler (CFB during coal and biomass co-combustion. Numerical computation results for three solid biomass fuels co-combustion with lignite are presented in the paper. The results of the calculation showed that in previously established kinetics equations for coal combustion, some reactions had to be modified as the combustion conditions changed with the fuel blend composition. Obtained CO2, CO, SO2 and NOx emissions are located in borders of ± 20% in the relationship to the experimental data. Experimental data was obtained for forest biomass, sunflower husk, willow and lignite cocombustion tests carried out on the atmospheric 261 MWe COMPACT CFB boiler operated in PGE Turow Power Station in Poland. The energy fraction of biomass in fuel blend was: 7%wt, 10%wt and 15%wt. The measured emissions of CO, SO2 and NOx (i.e. NO + NO2 were also shown in the paper. For all types of biomass added to the fuel blends the emission of the gaseous pollutants was lower than that for coal combustion.

  13. Constitutional reform as process

    OpenAIRE

    Schultze, Rainer-Olaf (Prof.)

    2000-01-01

    Constitutional reform as process. - In: The politics of constitutional reform in North America / Rainer-Olaf Schultze ... (eds.). - Opladen : Leske + Budrich, 2000. - S. 11-31. - (Politikwissenschaftliche paperbacks ; 30)

  14. Derivation of simplified basic equations of gas-liquid two-phase dispersed flow based on two-fluid model

    International Nuclear Information System (INIS)

    Kataoka, Isao; Tomiyama, Akio

    2004-01-01

    The simplified and physically reasonable basic equations for the gas-liquid dispersed flow were developed based on some appropriate assumptions and the treatment of dispersed phase as isothermal rigid particles. Based on the local instant formulation of mass, momentum and energy conservation of the dispersed flow, time-averaged equations were obtained assuming that physical quantities in the dispersed phase are uniform. These assumptions are approximately valid when phase change rate and/or chemical reaction rate are not so large at gas-liquid interface and there is no heat generation in within the dispersed phase. Detailed discussions were made on the characteristics of obtained basic equations and physical meanings of terms consisting the basic equations. It is shown that, in the derived averaged momentum equation, the terms of pressure gradient and viscous momentum diffusion do not appear and, in the energy equation, the term of molecular thermal diffusion heat flux does not appear. These characteristics of the derived equations were shown to be very consistent concerning the physical interpretation of the gas-liquid dispersed flow. Furthermore, the obtained basic equations are consistent with experiments for the dispersed flow where most of averaged physical quantities are obtained assuming that the distributions of those are uniform within the dispersed phase. Investigation was made on the problem whether the obtained basic equations are well-posed or ill-posed for the initial value problem. The eigenvalues of the simplified mass and momentum equations are calculated for basic equations obtained here and previous two-fluid basic equations with one pressure model. Well-posedness and ill-posedness are judged whether the eigenvalues are real or imaginary. The result indicated the newly developed basic equations always constitute the well-posed initial value problem while the previous two-fluid basic equations based on one pressure model constitutes ill

  15. Biomass resources in California

    Energy Technology Data Exchange (ETDEWEB)

    Tiangco, V.M.; Sethi, P.S. [California Energy Commission, Sacramento, CA (United States)

    1993-12-31

    The biomass resources in California which have potential for energy conversion were assessed and characterized through the project funded by the California Energy Commission and the US Department of Energy`s Western Regional Biomass Energy Program (WRBEP). The results indicate that there is an abundance of biomass resources as yet untouched by the industry due to technical, economic, and environmental problems, and other barriers. These biomass resources include residues from field and seed crops, fruit and nut crops, vegetable crops, and nursery crops; food processing wastes; forest slash; energy crops; lumber mill waste; urban wood waste; urban yard waste; livestock manure; and chaparral. The estimated total potential of these biomass resource is approximately 47 million bone dry tons (BDT), which is equivalent to 780 billion MJ (740 trillion Btu). About 7 million BDT (132 billion MJ or 124 trillion Btu) of biomass residue was used for generating electricity by 66 direct combustion facilities with gross capacity of about 800 MW. This tonnage accounts for only about 15% of the total biomass resource potential identified in this study. The barriers interfering with the biomass utilization both in the on-site harvesting, collection, storage, handling, transportation, and conversion to energy are identified. The question whether these barriers present significant impact to biomass {open_quotes}availability{close_quotes} and {open_quotes}sustainability{close_quotes} remains to be answered.

  16. Post-Revolution Constitutionalism: The Impact of Drafting Processes on the Constitutional Documents in Tunisia and Egypt

    DEFF Research Database (Denmark)

    Elsayed, Ahmed Mohamed Abdelfattah

    2014-01-01

    This paper seeks to address the constitutional paths that followed the Arab awakening in both Tunisia and Egypt. The Tunisian constitutional process, despite some tensions, was largely peaceful and consensual. On the other hand, the process in Egypt of establishing a new constitutional arrangement...... at identifying the factors have impacted both the constitutional drafting process and the popular perception of the produced constitutions in each of Tunisia and Egypt....

  17. Modelling of biomass pyrolysis

    International Nuclear Information System (INIS)

    Kazakova, Nadezhda; Petkov, Venko; Mihailov, Emil

    2015-01-01

    Pyrolysis is an essential preliminary step in a gasifier. The first step in modelling the pyrolysis process of biomass is creating a model for the chemical processes taking place. This model should describe the used fuel, the reactions taking place and the products created in the process. The numerous different polymers present in the organic fraction of the fuel are generally divided in three main groups. So, the multistep kinetic model of biomass pyrolysis is based on conventional multistep devolatilization models of the three main biomass components - cellulose, hemicelluloses, and lignin. Numerical simulations have been conducted in order to estimate the influence of the heating rate and the temperature of pyrolysis on the content of the virgin biomass, active biomass, liquid, solid and gaseous phases at any moment. Keywords: kinetic models, pyrolysis, biomass pyrolysis.

  18. A constitutive model for the flow through an assembly of circular section rods

    International Nuclear Information System (INIS)

    Moeller, S.V.

    1979-08-01

    The determination of the flow through an uniform array of rod bundle is made by means of the Continuum Theories of Mixtures, which gives balance equations for the system. The hypotheses of isothermal and fully developed turbulent flow are made. Constitutive equations for the resistive force are determined from Jakob's and Rowe's correlations, and its behaviour analysed for a standard case. Comparison of these equations with Bottgenbach's experiments shows good agreement of the direction of the pressure, although direct comparison between present theory and his theory is not possible. For the confirmation of the model an experiment is performed, this consisting of measuring pressure drop (Euler's Number) in the axial and transverse direction of a random array rod bundle at various angles as functions of velocity (Reynold's Number), which has good agreement, except on axial direction. At last, a sample problem is formulated with the purpose of showing the applicability of the model, this being the determination of pressure field due to the influence of a baffle. (Author) [pt

  19. Carbon-nitrogen interactions and biomass partitioning of Carex rostrata grown at three levels of nitrogen supply

    Energy Technology Data Exchange (ETDEWEB)

    Saarinen, T [Helsinki Univ. (Finland). Dept. of Ecology and Systematics

    1997-12-31

    Biomass and production of vascular plants constitutes a major source of carbon input in peatlands. As rates of decomposition vary considerably with depth, the vertical distribution of biomass may substantially affect accumulation of carbon in peatlands. Therefore, allocation patterns between shoot and roots are particularly important when considering carbon balance of peatland ecosystems. The stimulatory effect of increasing atmospheric concentration of CO{sub 2} or photosynthesis may increase availability of carbon to most C3 plants. Availability of nitrogen may also alter both due to increased atmospheric deposition and changer in mineralisation rates associated with climate change. Most root-shoot partitioning models predict that allocation of biomass is dependent of the availability and uptake of carbon and nitrogen. A decrease in supply of carbon would favour allocation to shoots and a decrease in supply of nitrogen would increase allocation to roots. At a cellular level, non structural carbohydrates and free amino acids are thought to represent the biochemically available fraction of carbon and nitrogen, respectively. The aim of this work is study the long-term growth responses of Carex rostrata to changes in the availability of nitrogen. Special attention is paid to soluble sugars ant free amino acids, which may control partitioning of biomass. (10 refs.)

  20. Carbon-nitrogen interactions and biomass partitioning of Carex rostrata grown at three levels of nitrogen supply

    Energy Technology Data Exchange (ETDEWEB)

    Saarinen, T. [Helsinki Univ. (Finland). Dept. of Ecology and Systematics

    1996-12-31

    Biomass and production of vascular plants constitutes a major source of carbon input in peatlands. As rates of decomposition vary considerably with depth, the vertical distribution of biomass may substantially affect accumulation of carbon in peatlands. Therefore, allocation patterns between shoot and roots are particularly important when considering carbon balance of peatland ecosystems. The stimulatory effect of increasing atmospheric concentration of CO{sub 2} or photosynthesis may increase availability of carbon to most C3 plants. Availability of nitrogen may also alter both due to increased atmospheric deposition and changer in mineralisation rates associated with climate change. Most root-shoot partitioning models predict that allocation of biomass is dependent of the availability and uptake of carbon and nitrogen. A decrease in supply of carbon would favour allocation to shoots and a decrease in supply of nitrogen would increase allocation to roots. At a cellular level, non structural carbohydrates and free amino acids are thought to represent the biochemically available fraction of carbon and nitrogen, respectively. The aim of this work is study the long-term growth responses of Carex rostrata to changes in the availability of nitrogen. Special attention is paid to soluble sugars ant free amino acids, which may control partitioning of biomass. (10 refs.)

  1. Biomass-to-hydrogen via fast pyrolysis and catalytic steam reforming

    Energy Technology Data Exchange (ETDEWEB)

    Chornet, E.; Wang, D.; Czernik, S. [National Renewable Energy Lab., Golden, CO (United States)] [and others

    1996-10-01

    Pyrolysis of lignocellulosic biomass and reforming the pyroligneous oils is being studied as a strategy for producing hydrogen. Novel technologies for the rapid pyrolysis of biomass have been developed in the past decade. They provide compact and efficient systems to transform biomass into vapors that are condensed to oils, with yields as high as 75-80 wt.% of the anhydrous biomass. This {open_quotes}bio-oil{close_quotes} is a mixture of aldehydes, alcohols, acids, oligomers from the constitutive carbohydrates and lignin, and some water derived from the dehydration reactions. Hydrogen can be produced by reforming the bio-oil or its fractions with steam. A process of this nature has the potential to be cost competitive with conventional means of producing hydrogen. The reforming facility can be designed to handle alternate feedstocks, such as natural gas and naphtha, if necessary. Thermodynamic modeling of the major constituents of the bio-oil has shown that reforming is possible within a wide range of temperatures and steam-to-carbon ratios. Existing catalytic data on the reforming of oxygenates have been studied to guide catalyst selection. Tests performed on a microreactor interfaced with a molecular beam mass spectrometer showed that, by proper selection of the process variables: temperature, steam-to-carbon ratio, gas hourly space velocity, and contact time, almost total conversion of carbon in the feed to CO and CO{sub 2} could be obtained. These tests also provided possible reaction mechanisms where thermal cracking competes with catalytic processes. Bench-scale, fixed bed reactor tests demonstrated high hydrogen yields from model compounds and carbohydrate-derived pyrolysis oil fractions. Reforming bio-oil or its fractions required proper dispersion of the liquid to avoid vapor-phase carbonization of the feed in the inlet to the reactor. A special spraying nozzle injector was designed and successfully tested with an aqueous fraction of bio-oil.

  2. Romania biomass energy. Country study

    Energy Technology Data Exchange (ETDEWEB)

    Burnham, M; Easterly, J L; Mark, P E; Keller, A [DynCorp, Alexandria, VA (United States)

    1995-12-01

    The present report was prepared under contract to UNIDO to conduct a case study of biomass energy use and potential in Romania. The purpose of the case study is to provide a specific example of biomass energy issues and potential in the context of the economic transition under way in eastern Europe. The transition of Romania to a market economy is proceeding at a somewhat slower pace than in other countries of eastern Europe. Unfortunately, the former regime forced the use of biomass energy with inadequate technology and infrastructure, particularly in rural areas. The resulting poor performance thus severely damaged the reputation of biomass energy in Romania as a viable, reliable resource. Today, efforts to rejuvenate biomass energy and tap into its multiple benefits are proving challenging. Several sound biomass energy development strategies were identified through the case study, on the basis of estimates of availability and current use of biomass resources; suggestions for enhancing potential biomass energy resources; an overview of appropriate conversion technologies and markets for biomass in Romania; and estimates of the economic and environmental impacts of the utilization of biomass energy. Finally, optimal strategies for near-, medium- and long-term biomass energy development, as well as observations and recommendations concerning policy, legislative and institutional issues affecting the development of biomass energy in Romania are presented. The most promising near-term biomass energy options include the use of biomass in district heating systems; cofiring of biomass in existing coal-fired power plants or combined heat and power plants; and using co-generation systems in thriving industries to optimize the efficient use of biomass resources. Mid-term and long-term opportunities include improving the efficiency of wood stoves used for cooking and heating in rural areas; repairing the reputation of biogasification to take advantage of livestock wastes

  3. Romania biomass energy. Country study

    International Nuclear Information System (INIS)

    Burnham, M.; Easterly, J.L.; Mark, P.E.; Keller, A.

    1995-01-01

    The present report was prepared under contract to UNIDO to conduct a case study of biomass energy use and potential in Romania. The purpose of the case study is to provide a specific example of biomass energy issues and potential in the context of the economic transition under way in eastern Europe. The transition of Romania to a market economy is proceeding at a somewhat slower pace than in other countries of eastern Europe. Unfortunately, the former regime forced the use of biomass energy with inadequate technology and infrastructure, particularly in rural areas. The resulting poor performance thus severely damaged the reputation of biomass energy in Romania as a viable, reliable resource. Today, efforts to rejuvenate biomass energy and tap into its multiple benefits are proving challenging. Several sound biomass energy development strategies were identified through the case study, on the basis of estimates of availability and current use of biomass resources; suggestions for enhancing potential biomass energy resources; an overview of appropriate conversion technologies and markets for biomass in Romania; and estimates of the economic and environmental impacts of the utilization of biomass energy. Finally, optimal strategies for near-, medium- and long-term biomass energy development, as well as observations and recommendations concerning policy, legislative and institutional issues affecting the development of biomass energy in Romania are presented. The most promising near-term biomass energy options include the use of biomass in district heating systems; cofiring of biomass in existing coal-fired power plants or combined heat and power plants; and using co-generation systems in thriving industries to optimize the efficient use of biomass resources. Mid-term and long-term opportunities include improving the efficiency of wood stoves used for cooking and heating in rural areas; repairing the reputation of biogasification to take advantage of livestock wastes

  4. The diffusion of constitutional rights

    NARCIS (Netherlands)

    Goderis, B.V.G.; Versteeg, M.

    Constitutions are commonly regarded as uniquely national products, shaped by domestic ideals and politics. This paper develops and empirically investigates a novel hypothesis, which is that constitutions are also shaped by transnational influence, or “diffusion.” Constitutional rights can diffuse

  5. Entrained Flow Gasification of Biomass

    DEFF Research Database (Denmark)

    Qin, Ke

    The present Ph. D. thesis describes experimental and modeling investigations on entrained flow gasification of biomass and an experimental investigation on entrained flow cogasification of biomass and coal. A review of the current knowledge of biomass entrained flow gasification is presented....... Biomass gasification experiments were performed in a laboratory-scale atmospheric pressure entrained flow reactor with the aim to investigate the effects of operating parameters and biomass types on syngas products. A wide range of operating parameters was involved: reactor temperature, steam/carbon ratio......, excess air ratio, oxygen concentration, feeder gas flow, and residence time. Wood, straw, and lignin were used as biomass fuels. In general, the carbon conversion was higher than 90 % in the biomass gasification experiments conducted at high temperatures (> 1200 °C). The biomass carbon...

  6. The limited contribution of large trees to annual biomass production in an old-growth tropical forest.

    Science.gov (United States)

    Ligot, Gauthier; Gourlet-Fleury, Sylvie; Ouédraogo, Dakis-Yaoba; Morin, Xavier; Bauwens, Sébastien; Baya, Fidele; Brostaux, Yves; Doucet, Jean-Louis; Fayolle, Adeline

    2018-04-16

    Although the importance of large trees regarding biodiversity and carbon stock in old-growth forests is undeniable, their annual contribution to biomass production and carbon uptake remains poorly studied at the stand level. To clarify the role of large trees in biomass production, we used data of tree growth, mortality, and recruitment monitored during 20 yr in 10 4-ha plots in a species-rich tropical forest (Central African Republic). Using a random block design, three different silvicultural treatments, control, logged, and logged + thinned, were applied in the 10 plots. Annual biomass gains and losses were analyzed in relation to the relative biomass abundance of large trees and by tree size classes using a spatial bootstrap procedure. Although large trees had high individual growth rates and constituted a substantial amount of biomass, stand-level biomass production decreased with the abundance of large trees in all treatments and plots. The contribution of large trees to annual stand-level biomass production appeared limited in comparison to that of small trees. This pattern did not only originate from differences in abundance of small vs. large trees or differences in initial biomass stocks among tree size classes, but also from a reduced relative growth rate of large trees and a relatively constant mortality rate among tree size classes. In a context in which large trees are increasingly gaining attention as being a valuable and a key structural characteristic of natural forests, the present study brought key insights to better gauge the relatively limited role of large trees in annual stand-level biomass production. In terms of carbon uptake, these results suggest, as already demonstrated, a low net carbon uptake of old-growth forests in comparison to that of logged forests. Tropical forests that reach a successional stage with relatively high density of large trees progressively cease to be carbon sinks as large trees contribute sparsely or even

  7. A Modified Eyring Equation for Modeling Yield and Flow Stresses of Metals at Strain Rates Ranging from 10−5 to 5 × 104 s−1

    Directory of Open Access Journals (Sweden)

    Ramzi Othman

    2015-01-01

    Full Text Available In several industrial applications, metallic structures are facing impact loads. Therefore, there is an important need for developing constitutive equations which take into account the strain rate sensitivity of their mechanical properties. The Johnson-Cook equation was widely used to model the strain rate sensitivity of metals. However, it implies that the yield and flow stresses are linearly increasing in terms of the logarithm of strain rate. This is only true up to a threshold strain rate. In this work, a three-constant constitutive equation, assuming an apparent activation volume which decreases as the strain rate increases, is applied here for some metals. It is shown that this equation fits well the experimental yield and flow stresses for a very wide range of strain rates, including quasi-static, high, and very high strain rates (from 10−5 to 5 × 104 s−1. This is the first time that a constitutive equation is showed to be able to fit the yield stress over a so large strain rate range while using only three material constants.

  8. Height and Biomass of Mangroves in Africa from ICEsat/GLAS and SRTM

    Science.gov (United States)

    Fatoyinbo, Temilola E.; Simard, Marc

    2012-01-01

    The accurate quantification of forest 3-D structure is of great importance for studies of the global carbon cycle and biodiversity. These studies are especially relevant in Africa, where deforestation rates are high and the lack of background data is great. Mangrove forests are ecologically significant and it is important to measure mangrove canopy heights and biomass. The objectives of this study are to estimate: 1. The total area, 2. Canopy height distributions and 3. Aboveground biomass of mangrove forests in Africa. To derive mangrove 3-D structure and biomass maps, we used a combination of mangrove maps derived from Landsat ETM+, LiDAR canopy height estimates from ICEsat/GLAS (Ice, Cloud, and land Elevation Satellite/Geoscience Laser Altimeter System) and elevation data from SRTM (Shuttle Radar Topography Mission) for the African continent. More specifically, we extracted mangrove forest areas on the SRTM DEM using Landsat based landcover maps. The LiDAR (Light Detection and Ranging) measurements from the large footprint GLAS sensor were used to derive local estimates of canopy height and calibrate the Interferometric Synthetic Aperture Radar (InSAR) data from SRTM. We then applied allometric equations relating canopy height to biomass in order to estimate above ground biomass (AGB) from the canopy height product. The total mangrove area of Africa was estimated to be 25 960 square kilometers with 83% accuracy. The largest mangrove areas and greatest total biomass was 29 found in Nigeria covering 8 573 km2 with 132 x10(exp 6) Mg AGB. Canopy height across Africa was estimated with an overall root mean square error of 3.55 m. This error also includes the impact of using sensors with different resolutions and geolocation error which make comparison between measurements sensitive to canopy heterogeneities. This study provides the first systematic estimates of mangrove area, height and biomass in Africa. Our results showed that the combination of ICEsat/GLAS and

  9. Multiscale Mathematics for Biomass Conversion to Renewable Hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Plechac, Petr [Univ. of Tennessee, Knoxville, TN (United States). Dept. of Mathematics; Univ. of Delaware, Newark, DE (United States). Dept. of Mathematics; Vlachos, Dionisios [Univ. of Delaware, Newark, DE (United States). Dept. of Chemical and Biomolecular Engineering; Katsoulakis, Markos [Univ. of Massachusetts, Amherst, MA (United States). Dept. of Mathematics

    2013-09-05

    The overall objective of this project is to develop multiscale models for understanding and eventually designing complex processes for renewables. To the best of our knowledge, our work is the first attempt at modeling complex reacting systems, whose performance relies on underlying multiscale mathematics. Our specific application lies at the heart of biofuels initiatives of DOE and entails modeling of catalytic systems, to enable economic, environmentally benign, and efficient conversion of biomass into either hydrogen or valuable chemicals. Specific goals include: (i) Development of rigorous spatio-temporal coarse-grained kinetic Monte Carlo (KMC) mathematics and simulation for microscopic processes encountered in biomass transformation. (ii) Development of hybrid multiscale simulation that links stochastic simulation to a deterministic partial differential equation (PDE) model for an entire reactor. (iii) Development of hybrid multiscale simulation that links KMC simulation with quantum density functional theory (DFT) calculations. (iv) Development of parallelization of models of (i)-(iii) to take advantage of Petaflop computing and enable real world applications of complex, multiscale models. In this NCE period, we continued addressing these objectives and completed the proposed work. Main initiatives, key results, and activities are outlined.

  10. Pretreated densified biomass products

    Science.gov (United States)

    Dale, Bruce E; Ritchie, Bryan; Marshall, Derek

    2014-03-18

    A product comprising at least one densified biomass particulate of a given mass having no added binder and comprised of a plurality of lignin-coated plant biomass fibers is provided, wherein the at least one densified biomass particulate has an intrinsic density substantially equivalent to a binder-containing densified biomass particulate of the same given mass and h a substantially smooth, non-flakey outer surface. Methods for using and making the product are also described.

  11. Bioethanol and power from integrated second generation biomass: A Monte Carlo simulation

    International Nuclear Information System (INIS)

    Osaki, Márcia R.; Seleghim, Paulo

    2017-01-01

    Highlights: • The impacts of integrating new sugarcane conversion using bagasse and straw. • Industrial conversion of sugarcane into energy carriers: ethanol and electricity. • A reference sugarcane industrial was simulated by the Monte Carlo method. • Simultaneously optimal ethanol production and electricity generation occur at low burning bagasse rates. - Abstract: The main objective of this work is to assess the impacts of integrating new biomass conversion technologies into an existing sugarcane industrial processing plant in terms of its multi-objective optimal operating conditions. A typical sugarcane mill is identified and a second generation ethanol production pathway is incorporated to give the operator the possibility of controlling the ratio between the rates of burning bagasse and straw (sugarcane tops and leaves) to their second generation processing to achieve optimal ethanol and electricity outputs. A set of equations describing the associated conversion unit operations and chemical reactions is simulated by the Monte Carlo method and the corresponding operating envelope is constructed and statistically analyzed. These equations permit to calculate ethanol production and electricity generation in terms of a virtually infinite number of scenarios characterized by two controlled variables (burning bagasse and straw mass flow rates) and several uncontrolled variables (biomass composition, cellulose, hemicelluloses and lignin yields, fermentation efficiencies, etc.). Results reveal that the input variables have specific statistical characteristics when the corresponding operating states lay near the maximum energy limit (Pareto frontier). For example, since the objectives being optimized are intrinsically antagonistic, i.e. the increase of one dictates the decrease of the other, it is better to convert bagasse to ethanol via second generation pathway because of the high energy requirements of its dewatering prior to combustion and low heat

  12. Legitimacy of Constitutional Justice: Democracy, Constitutional Court and Theory Against Majority Interest

    Directory of Open Access Journals (Sweden)

    Thaminne Nathalia Cabral Moraes e Silva

    2016-12-01

    Full Text Available This article has as its theme the analysis of the separation of powers and the rule of democracy, in addition to the possibility of the Constitutional Court be composed of people appointed by the President of the Republic, not fulfilling the democratic rule, and make the control of constitutionality of laws, created through democratic process. Will be answered: the separation of powers obey the democratic rule? When the Legislature fails to fulfill its function of legislating, opens the opportunity for the Supreme Court, as the Constitutional Court that is, create, through judicial activism, silent rules? That injured the democratic rule?

  13. News Media Analysis of Carbon Capture and Storage and Biomass: Perceptions and Possibilities

    Directory of Open Access Journals (Sweden)

    Andrea M. Feldpausch-Parker

    2015-04-01

    Full Text Available In the US, carbon capture and storage (CCS has received most of its attention when coupled with the fossil fuel industry as a mitigation strategy for climate change. CCS, which is constituted as a broad suite of capture and sequestration technologies and techniques, does not preclude coupling with other energy industries such as bioenergy (bioenergy and CCS or BECCS. In this paper, we examined news media coverage of CCS and biomass individually in locations throughout the US where these technologies are being explored to determine how they are perceived and what possibilities lay in their coupling for climate change mitigation. From our analyses, we found that individually, both CCS and biomass are perceived generally as beneficial for energy development by the news media, though they are not often mentioned in combination. Combined references do, however, speak to their value for climate change mitigation and as an alternative to fossil fuels.

  14. Legal theology in imposed constitutionalism

    DEFF Research Database (Denmark)

    Abat Ninet, Antoni

    2018-01-01

    The focus of this paper is the question of legitimacy, and how can we consider legitimate an imposed constitution and the subsequent constitutional principles, practices and values that go hand-in-hand with the legal and political acculturation. Constitutional texts around the world are good...

  15. Creep mechanisms and constitutive relations in pure metals

    International Nuclear Information System (INIS)

    Nix, W.D.

    1979-01-01

    The mechanisms of creep of pure metals is briefly reviewed and divided into two parts: steady state flow mechanisms, and non-steady state flow mechanisms and constitutive relations. Creep by diffusional flow is now reasonably well understood, with theory and experiment in good agreement. The closely related phenomenon of Harper--Dorn creep can also be understood in terms of diffusion between dislocations. Power law creep involves the climb of edge disloctions controlled by lattice self diffusion. Theoretical treatments of this process invariably give a power law exponent of 3. This natural creep law is compared with the data for FCC and BCC metals. It is suggested that diffusion controlled climb is the controlling process in BCC metals at very high temperatures. Stacking fault energy effects may preclude the possibility that creep is controlled entirely by lattice self diffusion in some FCC metals. The subject of power law breakdown is presented as a natural consequence of the transition to low temperature flow phenomena. The role of core diffusion in this transition is briefly discussed. The mechanisms are presented by which pure metals creep at elevated temperatures. While most of this review deals with the mechanisms of steady state flow, some discussion is devoted to creep flow under non-steady state conditions. This topic is discussed in connection with the development of constitutive equations for describing plastic flow in metals

  16. Method for pretreating lignocellulosic biomass

    Science.gov (United States)

    Kuzhiyil, Najeeb M.; Brown, Robert C.; Dalluge, Dustin Lee

    2015-08-18

    The present invention relates to a method for pretreating lignocellulosic biomass containing alkali and/or alkaline earth metal (AAEM). The method comprises providing a lignocellulosic biomass containing AAEM; determining the amount of the AAEM present in the lignocellulosic biomass; identifying, based on said determining, the amount of a mineral acid sufficient to completely convert the AAEM in the lignocellulosic biomass to thermally-stable, catalytically-inert salts; and treating the lignocellulosic biomass with the identified amount of the mineral acid, wherein the treated lignocellulosic biomass contains thermally-stable, catalytically inert AAEM salts.

  17. Biomass Maps | Geospatial Data Science | NREL

    Science.gov (United States)

    Biomass Maps Biomass Maps These maps illustrate the biomass resource in the United States by county . Biomass feedstock data are analyzed both statistically and graphically using a geographic information Data Science Team. Solid Biomass Resources Map of Total Biomass Resources in the United States Solid

  18. System and process for biomass treatment

    Science.gov (United States)

    Dunson, Jr., James B; Tucker, III, Melvin P; Elander, Richard T; Lyons, Robert C

    2013-08-20

    A system including an apparatus is presented for treatment of biomass that allows successful biomass treatment at a high solids dry weight of biomass in the biomass mixture. The design of the system provides extensive distribution of a reactant by spreading the reactant over the biomass as the reactant is introduced through an injection lance, while the biomass is rotated using baffles. The apparatus system to provide extensive assimilation of the reactant into biomass using baffles to lift and drop the biomass, as well as attrition media which fall onto the biomass, to enhance the treatment process.

  19. Dynamics, aboveground biomass and composition on permanent plots, Tambopata National Reserve. Madre de Dios, Peru

    Directory of Open Access Journals (Sweden)

    Nadir C. Pallqui

    2014-12-01

    Full Text Available In this study we evaluated the floristic composition and changes in stored biomass and dynamics over time in 9 permanent plots monitored by RAINFOR (Amazon Forest Inventory Network and located in the lowland Amazon rainforest of the Tambopata National Reserve. Data were acquired in the field using the standardized methodology of RAINFOR. The biomass was estimated using the equation for tropical moist forests of Chave et al. (2005. Biomass dynamics were analyzed, in three separated periods from 2003 to 2011. 64 families, 219 genera and 531 species were recorded. The tree floristic composition is very similar in all plots except for one swamp plot, although but it is also evident that two slightly different forest communities exist in the rest of landscape, apparently related to the age of the ancient river terraces in the area. Mortality and recruitment of individuals averaged 2.12 ± 0.52% and 1.92 ± 0.49%, respectively. The turnover rate is 2.02% per year. Aboveground biomass stored in these forests averages 296.2 ± 33.9 t ha-1. The biomass dynamics show a total net gain of 1.96, 1.69 and –1.23 t ha-1 for period respectively. Prior to the drought of 2010 a change in biomass was found 1.88 t ha-1 yr-1 and post drought was -0.18 t ha-1 yr-1 on average, though the difference is not significant. Demographic analysis suggests a dynamic equilibrium in the plots. The negative balance of biomass observed for the period 2008 – 2011 may be due to the drought of 2010, in which half of the monitored plots experienced negative net biomass change due to mortality of individuals selectively affecting the floristic composition.

  20. A new numerical approximation of the fractal ordinary differential equation

    Science.gov (United States)

    Atangana, Abdon; Jain, Sonal

    2018-02-01

    The concept of fractal medium is present in several real-world problems, for instance, in the geological formation that constitutes the well-known subsurface water called aquifers. However, attention has not been quite devoted to modeling for instance, the flow of a fluid within these media. We deem it important to remind the reader that the concept of fractal derivative is not to represent the fractal sharps but to describe the movement of the fluid within these media. Since this class of ordinary differential equations is highly complex to solve analytically, we present a novel numerical scheme that allows to solve fractal ordinary differential equations. Error analysis of the method is also presented. Application of the method and numerical approximation are presented for fractal order differential equation. The stability and the convergence of the numerical schemes are investigated in detail. Also some exact solutions of fractal order differential equations are presented and finally some numerical simulations are presented.

  1. Short-term Probabilistic Forecasting of Wind Speed Using Stochastic Differential Equations

    DEFF Research Database (Denmark)

    Iversen, Jan Emil Banning; Morales González, Juan Miguel; Møller, Jan Kloppenborg

    2016-01-01

    and uncertain nature. In this paper, we propose a modeling framework for wind speed that is based on stochastic differential equations. We show that stochastic differential equations allow us to naturally capture the time dependence structure of wind speed prediction errors (from 1 up to 24 hours ahead) and......It is widely accepted today that probabilistic forecasts of wind power production constitute valuable information for both wind power producers and power system operators to economically exploit this form of renewable energy, while mitigating the potential adverse effects related to its variable......, most importantly, to derive point and quantile forecasts, predictive distributions, and time-path trajectories (also referred to as scenarios or ensemble forecasts), all by one single stochastic differential equation model characterized by a few parameters....

  2. Forest biomass carbon stocks and variation in Tibet's carbon-dense forests from 2001 to 2050.

    Science.gov (United States)

    Sun, Xiangyang; Wang, Genxu; Huang, Mei; Chang, Ruiying; Ran, Fei

    2016-10-05

    Tibet's forests, in contrast to China's other forests, are characterized by primary forests, high carbon (C) density and less anthropogenic disturbance, and they function as an important carbon pool in China. Using the biomass C density data from 413 forest inventory sites and a spatial forest age map, we developed an allometric equation for the forest biomass C density and forest age to assess the spatial biomass C stocks and variation in Tibet's forests from 2001 to 2050. The results indicated that the forest biomass C stock would increase from 831.1 Tg C in 2001 to 969.4 Tg C in 2050, with a net C gain of 3.6 Tg C yr -1 between 2001 and 2010 and a decrease of 1.9 Tg C yr -1 between 2040 and 2050. Carbon tends to allocate more in the roots of fir forests and less in the roots of spruce and pine forests with increasing stand age. The increase of the biomass carbon pool does not promote significant augmentation of the soil carbon pool. Our findings suggest that Tibet's mature forests will remain a persistent C sink until 2050. However, afforestation or reforestation, especially with the larger carbon sink potential forest types, such as fir and spruce, should be carried out to maintain the high C sink capacity.

  3. Understanding the Environmental and Climate Impacts of Biomass Burning in Northern Sub-Saharan Africa

    Science.gov (United States)

    Ichoku, Charles; Gatebe, Charles; Bolten, John; Policelli, Fritz; Habib, Shahid; Lee, Jejung; Wang, Jun; Wilcox, Eric; Adegoke, Jimmy

    2011-01-01

    The northern sub-Saharan African (NSSA) region, bounded on the north and south by the Sahara and the Equator, respectively, and stretching from the West to the East African coastlines, has one of the highest biomass-burning rates per unit land area among all regions of the world. Because of the high concentration and frequency of fires in this region, with the associated abundance of heat release and gaseous and particulate smoke emissions, biomass-burning activity is believed to be one of the drivers of the regional carbon and energy cycles, with serious implications for the water cycle. A new interdisciplinary research effort sponsored by NASA is presently being focused on the NSSA region, to better understand the possible connection between the intense biomass burning observed from satellite year after year across the region and the rapid depletion of the regional water resources, as exemplified by the dramatic drying of Lake Chad. A combination of remote sensing and modeling approaches is being utilized in investigating multiple regional surface, atmospheric, and water-cycle processes, and inferring possible links between them. In this presentation, we will discuss preliminary results as well as the path toward improved understanding'of the interrelationships and feedbacks between the biomass burning and the environmental change dynamics in the NSSA region.

  4. A comparison of elastic-plastic and variable modulus-cracking constitutive models for prestressed concrete reactor vessels

    International Nuclear Information System (INIS)

    Anderson, C.A.; Smith, P.D.

    1979-01-01

    Numerical prediction of the behavior of prestressed concrete reactor vessels (PCRVs) under static, dynamic and long term loadings is complicated by the currently ill-defined behavior of concrete under stress and the three-dimensional nature of PCRVs. Which constitutive model most closely approximates the behavior of concrete in PCRVs under load has not yet been decided. Many equations for accurately modeling the three-dimensional behavior of PCRVs tax the capability of a most up-to-date computing system. The main purpose of this paper is to compare the characteristics of two constitutive models which have been proposed for concrete, variable modulus cracking model and elastic-plastic model. Moreover, the behavior of typical concrete structures was compared, the materials of which obey these constitutive laws. The response to internal pressure of PCRV structure, the constitutive models for concrete, the test problems using a thick-walled concrete ring and a rectangular concrete plate, and the analysis of an axisymmetric concrete pressure vessel PV-26 using the variable modulus cracking model of the ADINA code are explained. The variable modulus cracking model can predict the behavior of reinforced concrete structures well into the range of nonlinear behavior. (Kako, I.)

  5. Constitutive equations of a ballistic steel alloy as a function of temperature

    Directory of Open Access Journals (Sweden)

    Coghe F.

    2012-08-01

    Full Text Available In the present work, dynamic tests have been performed on a new ballistic steel alloy by means of split Hopkinson pressure bars (SHPB. The impact behavior was investigated for strain rates ranging from 1000 to 2500 s−1, and temperatures in the range from − 196 to 300∘C. A robotized sample device was developed for transferring the sample from the heating or cooling device to the position between the bars. Simulations of the temperature evolution and its distribution in the specimen were performed using the finite element method. Measurements with thermocouples added inside the sample were carried out in order to validate the FEM simulations. The results show that a thermal gradient is present inside the sample; the average temperature loss during the manipulation of the sample is evaluated. In a last stage, optimal material constants for different constitutive models (Johnson-Cook, Zerilli-Amstrong, Cowper-Symonds has been computed by fitting, in a least square sense, the numerical and experimental stress-strain curves. They have been implemented in a hydrocode for validation using a simple impact problem: an adapted projectile geometry with a truncated nose (.50 calibre fragment simulating projectiles was fired directly against an armor plate. The parameters of the selected strength and failure models were determined. There is a good correspondence between the experimental and computed results. Nevertheless, an improved failure model is necessary to get satisfactory computed residual projectile velocities.

  6. Political dimension of European constitutionalism

    Directory of Open Access Journals (Sweden)

    Kaplánová Patricia

    2015-04-01

    Full Text Available Author in the article tries to analyse different elements of document called European Constitution. Analysis is supported with theoretical framework of federalism, presented by Brezovšek. Authors is playing with idea of (confederal and international organization elements of European Constitution and their mix. They are also trying to set some connections between so called common European identity as necessary condition to give legitimacy to the European Constitution. This became important question after „votes of non-confidence“ to the European Constitution in France, despite it should be addressed already before. However, European Constitution is important document on the path of European integration and lack of support to it will slow down this process of widening and deepening European ties.

  7. COUNTERMAJORITARIAN INSTITUTIONS IN THE RUSSIAN CONSTITUTION OF 1993 AS AN INSTRUMENT ENSURING CONSTITUTIONAL AND POLITICAL STABILITY

    Directory of Open Access Journals (Sweden)

    S. Shakhray

    2018-01-01

    Full Text Available The article enriches the discussion on the legal reasons and conditions fostering the viability of democratic constitutions by analyzing the rich experience of the Russian Constitution of 1993. Particular attention is paid to the concept of countermajoritarian institutions. The authors elaborate the idea that countermajoritarian institutions can play an important role in ensuring the viability (put in other terms, the proper balance between stability, adaptability, and dynamic development of modern democratic constitutions as well as political regimes.The article presents evidence-based data showing that the President and the Constitutional Court of the Russian Federation systematically acted as countermajoritarian institutions at the initial stage of the implementation of the “blueprint for the future” set down in the 1993 Russian Constitution. As a result of the activities of these institutions, strong legal frameworks were created that are necessary for the establishment of anew constitutional system of the Russian state and law.Today, the Russian Constitution of 1993 is one of the longest lasting democratic constitutions in the world (the average “life expectancy” of democratic constitutions adopted over the past 250 years is about seventeen years. The study of the countermajoritarian provisions in the 1993 Russian Constitution is of both theoretical and practical importance. In particular, the results of the study can be useful in creating efficient legal instruments for the maintenance of political stability and social development management both within sovereign states and within interstate communities.

  8. Biomass catalysis and solvents; Biomasse catalyse et solvants

    Energy Technology Data Exchange (ETDEWEB)

    Pioch, D [CIRAD-AMIS, programme Agro-Alimentaire, 34 - Montpellier (France); Pouilloux, Y; Barrault, J [Centre National de la Recherche Scientifique (CNRS UMR 6503), ESIP, Lab. de Catalyse en Chimie Organique, 86 - Poitiers (France); and others

    2000-07-01

    How to develop new technics and products and at the same time to respect the environment? The biomass seems to be an interesting domain in this framework and this document allows the selection of performing products obtain by biomass. Among these products the solvents economic and environmental advantages or consequences are discussed. A great part is also devoted to the voc emissions, bound to the solvents.

  9. Multi-functional biomass systems

    NARCIS (Netherlands)

    Dornburg, Veronika

    2004-01-01

    Biomass can play a role in mitigating greenhouse gas emissions by substituting conventional materials and supplying biomass based fuels. Main reason for the low share of biomass applications in Europe is their often-high production costs, among others due to the relatively low availability of

  10. Some applications of linear difference equations in finance with wolfram|alpha and maple

    Directory of Open Access Journals (Sweden)

    Dana Rıhová

    2014-12-01

    Full Text Available The principle objective of this paper is to show how linear difference equations can be applied to solve some issues of financial mathematics. We focus on the area of compound interest and annuities. In both cases we determine appropriate recursive rules, which constitute the first order linear difference equations with constant coefficients, and derive formulas required for calculating examples. Finally, we present possibilities of application of two selected computer algebra systems Wolfram|Alpha and Maple in this mathematical area.

  11. Biomass Torrefaction Process Review and Moving Bed Torrefaction System Model Development

    Energy Technology Data Exchange (ETDEWEB)

    Jaya Shakar Tumuluru; Shahab Sokhansanj; Christopher T. Wright; Richard D. Boardman

    2010-08-01

    Torrefaction is currently developing as an important preprocessing step to improve the quality of biomass in terms of physical properties, and proximate and ultimate composition. Torrefaction is a slow heating of biomass in an inert or reduced environment to a maximum temperature of 300 C. Torrefaction can also be defined as a group of products resulting from the partially controlled and isothermal pyrolysis of biomass occurring in a temperature range of 200-230 C and 270-280 C. Thus, the process can also be called a mild pyrolysis as it occurs at the lower temperature range of the pyrolysis process. At the end of the torrefaction process, a solid uniform product with lower moisture content and higher energy content than raw biomass is produced. Most of the smoke-producing compounds and other volatiles are removed during torrefaction, producing a final product that will have a lower mass but a higher heating value. An important aspect of research is to establish a degree of torrefaction where gains in heating value offset the loss of mass. There is a lack of literature on torrefaction reactor designs and a design sheet for estimating the dimensions of the torrefier based on capacity. This study includes (a) conducting a detailed review on the torrefaction of biomass in terms of understanding the process, product properties, off-gas compositions, and methods used, and (b) to design a moving bed torrefier, taking into account the basic fundamental heat and mass transfer calculations. Specific objectives include calculating the dimensions like diameter and height of the moving packed bed for different capacities, designing the heat loads and gas flow rates, and developing an interactive excel sheet where the user can define design specifications. In this report, 25-1000 kg/hr are used in equations for the design of the torrefier, examples of calculations, and specifications for the torrefier.

  12. Biomass energy

    International Nuclear Information System (INIS)

    Pasztor, J.; Kristoferson, L.

    1992-01-01

    Bioenergy systems can provide an energy supply that is environmentally sound and sustainable, although, like all energy systems, they have an environmental impact. The impact often depends more on the way the whole system is managed than on the fuel or on the conversion technology. The authors first describe traditional biomass systems: combustion and deforestation; health impact; charcoal conversion; and agricultural residues. A discussion of modern biomass systems follows: biogas; producer gas; alcohol fuels; modern wood fuel resources; and modern biomass combustion. The issue of bioenergy and the environment (land use; air pollution; water; socioeconomic impacts) and a discussion of sustainable bioenergy use complete the paper. 53 refs., 9 figs., 14 tabs

  13. Climate change impact on landscape fire and forest biomass dynamics

    International Nuclear Information System (INIS)

    Li, C.

    2004-01-01

    The aim of this study was to improve current understandings of fire regimes. The estimation of biomass dynamics at the stand scale is essential for understanding landscape scale biomass dynamics, particularly in order to understand the potential effects of fire regimes. This study presented a synthesis of research results obtained from stand scale studies together with fire behaviour and weather variables. Landscape structure, topography and climate conditions were also considered. Integration of the data was conducted with the SEM-LAND model, a spatially explicit model for landscape dynamics. Equations for the model were presented, including fire initiation and spread, as well as a lightning fire process and simulated fire suppression. Results indicated that fire suppression could alter the distribution of fire sizes. The effect of tree and stand mortality on forest biomass estimates was also discussed along with the impact of climate change on fire regimes. Results indicate that fire activities are likely to increase. Results also demonstrate that fire frequency and size distribution are correlated without human intervention. Theoretical negative exponential forest age distribution is not always supported by empirical observations. Point-based fire frequency and fire cycle definitions are special cases from a computational perspective. Detection of quantitative interrelationships may simplify preconditions for estimating fire regimes, and serve as a means to address incomplete empirical observations. 12 refs., 3 figs

  14. Vegetal and animal biomass; Les biomasses vegetales et animales

    Energy Technology Data Exchange (ETDEWEB)

    Combarnous, M. [Bordeaux-1 Univ., Lab. Energetique et Phenomenes de Transfert, UMR CNRS ENSAM, 33 - Talence (France)

    2005-07-01

    This presentation concerns all types of biomass of the earth and the seas and the relative implicit consumptions. After an evaluation of the food needs of the human being, the author discusses the solar energy conversion, the energetic flux devoted to the agriculture production, the food chain and the biomass. (A.L.B.)

  15. Modeling tree crown dynamics with 3D partial differential equations.

    Science.gov (United States)

    Beyer, Robert; Letort, Véronique; Cournède, Paul-Henry

    2014-01-01

    We characterize a tree's spatial foliage distribution by the local leaf area density. Considering this spatially continuous variable allows to describe the spatiotemporal evolution of the tree crown by means of 3D partial differential equations. These offer a framework to rigorously take locally and adaptively acting effects into account, notably the growth toward light. Biomass production through photosynthesis and the allocation to foliage and wood are readily included in this model framework. The system of equations stands out due to its inherent dynamic property of self-organization and spontaneous adaptation, generating complex behavior from even only a few parameters. The density-based approach yields spatially structured tree crowns without relying on detailed geometry. We present the methodological fundamentals of such a modeling approach and discuss further prospects and applications.

  16. Burnout of pulverized biomass particles in large scale boiler – Single particle model approach

    DEFF Research Database (Denmark)

    Saastamoinen, Jaakko; Aho, Martti; Moilanen, Antero

    2010-01-01

    the particle combustion model is coupled with one-dimensional equation of motion of the particle, is applied for the calculation of the burnout in the boiler. The particle size of biomass can be much larger than that of coal to reach complete burnout due to lower density and greater reactivity. The burner...... location and the trajectories of the particles might be optimised to maximise the residence time and burnout....

  17. Biomass steam gasification for production of SNG – Process design and sensitivity analysis

    International Nuclear Information System (INIS)

    Gröbl, Thomas; Walter, Heimo; Haider, Markus

    2012-01-01

    Highlights: ► A model for the SNG-production process from biomass to raw-SNG is prepared. ► A thermodynamic equilibrium model of the Biomass-Heatpipe-Reformer is developed. ► A sensitivity analysis on the most important operation parameters is carried out. ► Adopting the steam excess ratio a syngas ideally suitable for SNG production is generated. ► Thermodynamic equilibrium models are a useful tool for process design. -- Abstract: A process design for small-scale production of Substitute Natural Gas (SNG) by steam gasification of woody biomass is performed. In the course of this work, thermodynamic models for the novel process steps are developed and implemented into an already existing model library of commercial process simulation software IPSEpro. Mathematical models for allothermal steam gasification of biomass as well as for cleaning and methanation of product gas are provided by applying mass balances, energy balances and thermodynamic equilibrium equations. Using these models the whole process is integrated into the simulation software, a flowsheet for an optimum thermal integration of the single process steps is determined and energy savings are identified. Additionally, a sensitivity study is carried out in order to analyze the influence of various operation parameters. Their effects on amount and composition of the product gas and process efficiency are evaluated and discussed within this article.

  18. Constitutive Relationship Modeling and Characterization of Flow Behavior under Hot Working for Fe–Cr–Ni–W–Cu–Co Super-Austenitic Stainless Steel

    Directory of Open Access Journals (Sweden)

    Li-Chih Yang

    2015-09-01

    Full Text Available The hot deformation behavior of a Fe–22Cr–25Ni–3.5W–3Cu–1.5Co super-austenitic stainless steel was investigated using isothermal compression tests with a wide range of temperatures (1173–1373 K and strain rates (0.1–10 s−1. The results showed that all the flow curves gradually turned to balanced stress state without notable peak stress characteristics during the entire deformation, which indicated that the dynamic recovery behavior played a main restoration mechanism in the steel. Modeling constitutive equations relating to the temperature, strain rate and flow stress were proposed to determine the materials constants and activation energy necessary for deformation. In order to give the precise predicted values of the flow behavior, the influence of strain was identified using polynomial functions. The relationship of flow stress, temperature and strain rate was represented by the Zener-Hollomon parameter including the Arrhenius term. The predicted results validated that the developed constitutive equations can describe high temperature flow behavior well. Furthermore, a modified Zener-Hollomon parameter map of the studied steel was developed to clarify the restoration mechanism based on the constitutive modeling data and microstructural observation.

  19. Non-chaotic behaviour for a class of quadratic jerk equations

    International Nuclear Information System (INIS)

    Malasoma, J.-M.

    2009-01-01

    It is shown that a class constituted by 27 different types of non-linear third-order differential equations of the form x - =j(x,x . ,x), where j is a quadratic polynomial with only one or two terms, and for which ∂j(x,y,z)/∂z is not a constant function of time, does not exhibit chaos. The three-dimensional dynamical systems associated to these equations are not necessarily dissipative everywhere nor conservative everywhere in the corresponding phase spaces. Our results include and improve some recent results obtained by Yang and Chen who only considered the case where j was a homogeneous quadratic polynomial with two terms.

  20. Forest soil carbon is threatened by intensive biomass harvesting.

    Science.gov (United States)

    Achat, David L; Fortin, Mathieu; Landmann, Guy; Ringeval, Bruno; Augusto, Laurent

    2015-11-04

    Forests play a key role in the carbon cycle as they store huge quantities of organic carbon, most of which is stored in soils, with a smaller part being held in vegetation. While the carbon storage capacity of forests is influenced by forestry, the long-term impacts of forest managers' decisions on soil organic carbon (SOC) remain unclear. Using a meta-analysis approach, we showed that conventional biomass harvests preserved the SOC of forests, unlike intensive harvests where logging residues were harvested to produce fuelwood. Conventional harvests caused a decrease in carbon storage in the forest floor, but when the whole soil profile was taken into account, we found that this loss in the forest floor was compensated by an accumulation of SOC in deeper soil layers. Conversely, we found that intensive harvests led to SOC losses in all layers of forest soils. We assessed the potential impact of intensive harvests on the carbon budget, focusing on managed European forests. Estimated carbon losses from forest soils suggested that intensive biomass harvests could constitute an important source of carbon transfer from forests to the atmosphere (142-497 Tg-C), partly neutralizing the role of a carbon sink played by forest soils.

  1. Remarks on energetic biomass

    International Nuclear Information System (INIS)

    Mathis, Paul; Pelletier, Georges

    2011-01-01

    The authors report a study of energy biomass by considering its three main sources (forest, agriculture and wastes) and three energy needs (heat, fuel for transports, electricity) in the French national context. After having recalled the various uses of biomass (animal feeding, energy production, materials, chemical products), the authors discuss the characteristics of biomass with respect to other energy sources. Then, they analyse and discuss the various energy needs which biomass could satisfy: heat production (in industry, in the residential and office building sector), fuel for transports, electricity production. They assess and discuss the possible biomass production of its three main sources: forest, agriculture, and wastes (household, agricultural and industrial wastes). They also discuss the opportunities for biogas production and for second generation bio-fuel production

  2. Black hole entropy functions and attractor equations

    International Nuclear Information System (INIS)

    Lopes Cardoso, Gabriel; Wit, Bernard de; Mahapatra, Swapna

    2007-01-01

    The entropy and the attractor equations for static extremal black hole solutions follow from a variational principle based on an entropy function. In the general case such an entropy function can be derived from the reduced action evaluated in a near-horizon geometry. BPS black holes constitute special solutions of this variational principle, but they can also be derived directly from a different entropy function based on supersymmetry enhancement at the horizon. Both functions are consistent with electric/magnetic duality and for BPS black holes their corresponding OSV-type integrals give identical results at the semi-classical level. We clarify the relation between the two entropy functions and the corresponding attractor equations for N = 2 supergravity theories with higher-derivative couplings in four space-time dimensions. We discuss how non-holomorphic corrections will modify these entropy functions

  3. Aboveground allometric models for freeze-affected black mangroves (Avicennia germinans): equations for a climate sensitive mangrove-marsh ecotone

    Science.gov (United States)

    Osland, Michael J.; Day, Richard H.; Larriviere, Jack C.; From, Andrew S.

    2014-01-01

    Across the globe, species distributions are changing in response to climate change and land use change. In parts of the southeastern United States, climate change is expected to result in the poleward range expansion of black mangroves (Avicennia germinans) at the expense of some salt marsh vegetation. The morphology of A. germinans at its northern range limit is more shrub-like than in tropical climes in part due to the aboveground structural damage and vigorous multi-stem regrowth triggered by extreme winter temperatures. In this study, we developed aboveground allometric equations for freeze-affected black mangroves which can be used to quantify: (1) total aboveground biomass; (2) leaf biomass; (3) stem plus branch biomass; and (4) leaf area. Plant volume (i.e., a combination of crown area and plant height) was selected as the optimal predictor of the four response variables. We expect that our simple measurements and equations can be adapted for use in other mangrove ecosystems located in abiotic settings that result in mangrove individuals with dwarf or shrub-like morphologies including oligotrophic and arid environments. Many important ecological functions and services are affected by changes in coastal wetland plant community structure and productivity including carbon storage, nutrient cycling, coastal protection, recreation, fish and avian habitat, and ecosystem response to sea level rise and extreme climatic events. Coastal scientists in the southeastern United States can use the identified allometric equations, in combination with easily obtained and non-destructive plant volume measurements, to better quantify and monitor ecological change within the dynamic, climate sensitive, and highly-productive mangrove-marsh ecotone.

  4. Aboveground allometric models for freeze-affected black mangroves (Avicennia germinans): equations for a climate sensitive mangrove-marsh ecotone.

    Science.gov (United States)

    Osland, Michael J; Day, Richard H; Larriviere, Jack C; From, Andrew S

    2014-01-01

    Across the globe, species distributions are changing in response to climate change and land use change. In parts of the southeastern United States, climate change is expected to result in the poleward range expansion of black mangroves (Avicennia germinans) at the expense of some salt marsh vegetation. The morphology of A. germinans at its northern range limit is more shrub-like than in tropical climes in part due to the aboveground structural damage and vigorous multi-stem regrowth triggered by extreme winter temperatures. In this study, we developed aboveground allometric equations for freeze-affected black mangroves which can be used to quantify: (1) total aboveground biomass; (2) leaf biomass; (3) stem plus branch biomass; and (4) leaf area. Plant volume (i.e., a combination of crown area and plant height) was selected as the optimal predictor of the four response variables. We expect that our simple measurements and equations can be adapted for use in other mangrove ecosystems located in abiotic settings that result in mangrove individuals with dwarf or shrub-like morphologies including oligotrophic and arid environments. Many important ecological functions and services are affected by changes in coastal wetland plant community structure and productivity including carbon storage, nutrient cycling, coastal protection, recreation, fish and avian habitat, and ecosystem response to sea level rise and extreme climatic events. Coastal scientists in the southeastern United States can use the identified allometric equations, in combination with easily obtained and non-destructive plant volume measurements, to better quantify and monitor ecological change within the dynamic, climate sensitive, and highly-productive mangrove-marsh ecotone.

  5. Indian Farmers’ Perceptions and Willingness to Supply Surplus Biomass to an Envisioned Biomass-Based Power Plant

    Directory of Open Access Journals (Sweden)

    Anas Zyadin

    2015-04-01

    Full Text Available The main objectives of this socio-technical study are to investigate the Indian farmers’ biomass production capacities and their perceptions and willingness to supply their surplus biomass to fuel an envisioned biomass-based power plant in three selected Indian states: Maharashtra, Madhya Pradesh and Tamil Nadu. For doing so, 471 farmers (about one-third from each state have been interviewed in the field with info-sheet filled in by the field investigators. The farmers from all of the states appeared very much willing to sell their surplus biomass directly to a power plant. The farmers seem to depreciate the involvement of a middleman in the biomass procurement process. The farmers, however, appeared to highly appreciate a community-based association to regulate the biomass prices, with varying perceptions regarding government intervention. The majority of the farmers perceived the establishment of a biomass-based power plant in their region with positive economic outcomes. The farmers identified several barriers to supply biomass to a power plant where transportation logistics appeared to be the main barrier. The study recommends considering biomass collection, storage and transportation logistics as a fundamental segment of any envisioned investment in a biomass-based power plant. Biomass processing, such as pelletization or briquetting is recommended for efficient transportation of biomass at longer distances to reduce the transportation costs. The study further encourages the establishment of a farmers’ association aimed at collecting and selling biomass in agriculture areas predominant for small land holdings.

  6. Accounting for biomass carbon stock change due to wildfire in temperate forest landscapes in Australia.

    Science.gov (United States)

    Keith, Heather; Lindenmayer, David B; Mackey, Brendan G; Blair, David; Carter, Lauren; McBurney, Lachlan; Okada, Sachiko; Konishi-Nagano, Tomoko

    2014-01-01

    Carbon stock change due to forest management and disturbance must be accounted for in UNFCCC national inventory reports and for signatories to the Kyoto Protocol. Impacts of disturbance on greenhouse gas (GHG) inventories are important for many countries with large forest estates prone to wildfires. Our objective was to measure changes in carbon stocks due to short-term combustion and to simulate longer-term carbon stock dynamics resulting from redistribution among biomass components following wildfire. We studied the impacts of a wildfire in 2009 that burnt temperate forest of tall, wet eucalypts in south-eastern Australia. Biomass combusted ranged from 40 to 58 tC ha(-1), which represented 6-7% and 9-14% in low- and high-severity fire, respectively, of the pre-fire total biomass carbon stock. Pre-fire total stock ranged from 400 to 1040 tC ha(-1) depending on forest age and disturbance history. An estimated 3.9 TgC was emitted from the 2009 fire within the forest region, representing 8.5% of total biomass carbon stock across the landscape. Carbon losses from combustion were large over hours to days during the wildfire, but from an ecosystem dynamics perspective, the proportion of total carbon stock combusted was relatively small. Furthermore, more than half the stock losses from combustion were derived from biomass components with short lifetimes. Most biomass remained on-site, although redistributed from living to dead components. Decomposition of these components and new regeneration constituted the greatest changes in carbon stocks over ensuing decades. A critical issue for carbon accounting policy arises because the timeframes of ecological processes of carbon stock change are longer than the periods for reporting GHG inventories for national emissions reductions targets. Carbon accounts should be comprehensive of all stock changes, but reporting against targets should be based on human-induced changes in carbon stocks to incentivise mitigation activities.

  7. Estimate of biomass and carbon pools in disturbed and undisturbed oak forests in Tunisia

    Energy Technology Data Exchange (ETDEWEB)

    Zribi, L.; Chaar, H.; Khaldi, A.; Henchi, B.; Mouillot, F.; Gharbi, F.

    2016-07-01

    Aim of the study. To estimate biomass and carbon accumulation in a young and disturbed forest (regenerated after a tornado) and an aged cork oak forest (undisturbed forest) as well as its distribution among the different pools (tree, litter and soil). Area of study. The north west of Tunisia. Material and methods. Carbon stocks were evaluated in the above and belowground cork oak trees, the litter and the 150 cm of the soil. Tree biomass was estimated in both young and aged forests using allometric biomass equations developed for wood stem, cork stem, wood branch, cork branch, leaves, roots and total tree biomass based on combinations of diameter at breast height, total height and crown length as independent variables. Main results. Total tree biomass in forests was 240.58 Mg ha-1 in the young forest and 411.30 Mg ha-1 in the aged forest with a low root/shoot ratio (0.41 for young forest and 0.31 for aged forest). Total stored carbon was 419.46 Mg C ha-1 in the young forest and 658.09 Mg C ha-1 in the aged forest. Carbon stock (Mg C ha-1) was estimated to be113.61(27.08%) and 194.08 (29.49%) in trees, 3.55 (0.85%) and 5.73 (0.87%) in litter and 302.30 (72.07%) and 458.27 (69.64%) in soil in the young and aged forests, respectively. Research highlights. Aged undisturbed forest had the largest tree biomass but a lower potential for accumulation of carbon in the future; in contrast, young disturbed forest had both higher growth and carbon storage potential. (Author)

  8. Biomass Scenario Model | Energy Analysis | NREL

    Science.gov (United States)

    Biomass Scenario Model Biomass Scenario Model The Biomass Scenario Model (BSM) is a unique range of lignocellulosic biomass feedstocks into biofuels. Over the past 25 years, the corn ethanol plant matter (lignocellulosic biomass) to fermentable sugars for the production of fuel ethanol

  9. The Obligations on Government and Society in our Constitutional State to Respect and Support Independent Constitutional Structures

    Directory of Open Access Journals (Sweden)

    LWH Ackermann

    2000-05-01

    Full Text Available Constitutional democracy recognises the ancient democratic principle that government of a country is based on and legitimated by the will and consent of the governed, which is determined by regular multi-party elections based on universal adult franchise. Constitutional democracy limits this principle by subjecting the democratically elected government and the will of the majority subject to a written constitution and the norms embodied in it. Such constitution is enshrined as the supreme law of the country in question. An almost universal feature of modern constitutionalism is a Bill of Rights that forms part of the Constitution and which is designed to protect and enforce individual rights principally, although not exclusively, against the state. Constitutionalism also embodies the principle of the separation of powers. A competent and independent judiciary, with the power to review all legislative and executive conduct that is inconsistent with the Constitution, is regarded, almost universally, as the prime and most effective check on the legislative and executive branches of government. Recently it has come to be realised that for the truly effective and meaningful operation of constitutionalism, other independent state institutions are necessary. The collective objective of these institutions is to ensure that the Constitution in fact produces what it proclaims: that constitutionalism becomes a way of life in all institutional structures. The South African Constitution has clearly designated the judiciary as the prime upholder and enforcer of the Constitution. The Constitution has, however, gone further and makes provision for a variety of independent state institutions whose purpose is to "strengthen constitutional democracy in the Republic". Apart from these state institutions the Constitution also makes provision for other independent bodies designed to play an important checking and balancing role. The regular effective functioning of

  10. An alternative to the TEM (Transformed Eulerian Mean) equations

    Science.gov (United States)

    Gaßmann, Almut

    2013-04-01

    The TEM equations constitute a powerful means to get access to the residual circulation. However, due to their foundation on the wave perspective, they deliver only a zonally averaged picture without access to the three-dimensional structure or the local origins of the residual circulation. Therefore it is worth to investigate whether there are alternatives. The pathway followed here is to perform a transformation of the momentum and the potential temperature equation before taking the zonal mean. This is done by removing the steady state ideal wind solution vid = ?×?B-(?±P) from the equations (? - potential temperature, B - Bernoulli function, P - Ertel's potential vorticity EPV, ?± - density). The advantage of that approach is that the total EPV-flux does no longer contain an explicitly visible 'do-nothing-flux'. This flux, ?? ×?B, does only vanish when averaging on isentropic surfaces, but not on other isosurfaces. Here we find the reason why the conventional zonal mean on isentropes delivers a direct overturning cell on each hemisphere, whereas on other isosurfaces we obtain the typical three-cell structure with Headley, Ferrel, and polar cells. It will be demonstrated and made visible through idealized climate experiments with the ICON-IAP model that the zonal averages of the nonideal wind components vnid = v - vid and wnid = w - wid constitute similar direct overturning cells on non-isentropic surfaces as obtained with the TEM-generated v* and w*. It is also interesting to inspect fields of local nonideal wind components, the very origin of the residual circulation.

  11. 'Biomass lung': primitive biomass combustion and lung disease

    International Nuclear Information System (INIS)

    Baris, Y. I.; Seyfikli, Z.; Demir, A.; Hoskins, J. A.

    2002-01-01

    Domestic burning of biomass fuel is one of the most important risk factors for the development of respiratory diseases and infant mortality. The fuel which causes the highest level of disease is dung. In the rural areas of developing countries some 80% of households rely on biomass fuels for cooking and often heating as well and so suffer high indoor air pollution. Even when the fire or stove is outside the home those near it are still exposed to the smoke. In areas where the winters are long and cold the problem is aggravated since the fire or stove is indoors for many months of the year. The consequence of biomass burning is a level of morbidity in those exposed to the smoke as well as mortality. The rural areas of Turkey are among many in the world where biomass is the major fuel source. In this case report 8 patients from rural areas, particularly Anatolia, who used biomass are presented. Many of these are non-smoking, female patients who have respiratory complaints and a clinical picture of the chronic lung diseases which would have been expected if they had been heavy smokers. Typically patients cook on the traditional 'tandir' stove using dung and crop residues as the fuel. Ventilation systems are poor and they are exposed to a high level of smoke pollution leading to cough and dyspnoea. Anthracosis is a common outcome of this level of exposure and several of the patients developed lung tumours. The findings from clinical examination of 8 of these patients (2 M, 6 F) are presented together with their outcome where known. (author)

  12. Improved prediction of hardwood tree biomass derived from wood density estimates and form factors for whole trees

    Science.gov (United States)

    David W. MacFarlane; Neil R. Ver Planck

    2012-01-01

    Data from hardwood trees in Michigan were analyzed to investigate how differences in whole-tree form and wood density between trees of different stem diameter relate to residual error in standard-type biomass equations. The results suggested that whole-tree wood density, measured at breast height, explained a significant proportion of residual error in standard-type...

  13. Integration of biomass data in the dynamic vegetation model ORCHIDEE

    Science.gov (United States)

    Delbart, N.; Viovy, N.; Ciais, P.; Le Toan, T.

    2009-04-01

    Dynamic vegetation models (DVMs) are aimed at estimating exchanges between the terrestrial vegetated surface and the atmosphere, and the spatial distribution of natural vegetation types. For this purpose, DVMs use the climatic data alone to feed the vegetation process equations. As dynamic models, they can also give predictions under the current and the future climatic conditions. However, they currently lack accuracy in locating carbon stocks, sinks and sources, and in getting the correct magnitude. Consequently they have been essentially used to compare the vegetation responses under different scenarii. The assimilation of external data such as remote sensing data has been shown to improve the simulations. For example, the land cover maps are used to force the correct distribution of plant functional types (PFTs), and the leaf area index data is used to force the photosynthesis processes. This study concerns the integration of biomass data within the DVM ORCHIDEE. The objective here is to have the living carbon stocks with the correct magnitude and the correct location. Carbon stocks depend on interplay of carbon assimilated by photosynthesis, and carbon lost by respiration, mortality and disturbance. Biomass data can therefore be used as one essential constraint on this interplay. In this study, we use a large database provided by in-situ measurements of carbon stocks and carbon fluxes of old growth forests to constraint this interplay. For each PFT, we first adjust the simulated photosynthesis by reducing the mean error with the in situ measurements. Then we proceed similarly to adjust the autotrophic respiration. We then compare the biomass measured, and adjust the mortality processes in the model. Second, when processes are adjusted for each PFT to minimize the mean error on the carbon stock, biomass measurements can be assimilated. This assimilation is based on the hypothesis that the main variable explaining the biomass level at a given location is the age

  14. Process for treating biomass

    Science.gov (United States)

    Campbell, Timothy J.; Teymouri, Farzaneh

    2018-04-10

    This invention is directed to a process for treating biomass. The biomass is treated with a biomass swelling agent within the vessel to swell or rupture at least a portion of the biomass. A portion of the swelling agent is removed from a first end of the vessel following the treatment. Then steam is introduced into a second end of the vessel different from the first end to further remove swelling agent from the vessel in such a manner that the swelling agent exits the vessel at a relatively low water content.

  15. EnerGEO biomass pilot

    International Nuclear Information System (INIS)

    Tum, M.; Guenther, K.P.; McCallum, I.; Balkovic, J.; Khabarov, N.; Kindermann, G.; Leduc, S.; Biberacher, M.

    2013-01-01

    In the framework of the EU FP7 project EnerGEO (Earth Observations for Monitoring and Assessment of the Environmental Impact of Energy Use) sustainable energy potentials for forest and agricultural areas were estimated by applying three different model approaches. Firstly, the Biosphere Energy Transfer Hydrology (BETHY/DLR) model was applied to assess agricultural and forest biomass increases on a regional scale with the extension to grassland. Secondly, the EPIC (Environmental Policy Integrated Climate) - a cropping systems simulation model - was used to estimate grain yields on a global scale and thirdly the Global Forest Model (G4M) was used to estimate global woody biomass harvests and stock. The general objective of the biomass pilot is to implement the observational capacity for using biomass as an important current and future energy resource. The scope of this work was to generate biomass energy potentials for locations on the globe and to validate these data. Therefore, the biomass pilot was focused to use historical and actual remote sensing data as input data for the models. For validation purposes, forest biomass maps for 1987 and 2002 for Germany (Bundeswaldinventur (BWI-2)) and 2001 and 2008 for Austria (Austrian Forest Inventory (AFI)) were prepared as reference. (orig.)

  16. EnerGEO biomass pilot

    Energy Technology Data Exchange (ETDEWEB)

    Tum, M.; Guenther, K.P. [German Aerospace Center (DLR), Wessling (Germany). German Remote Sensing Data Center (DFD); McCallum, I.; Balkovic, J.; Khabarov, N.; Kindermann, G.; Leduc, S. [International Institute for Applied Systems Analysis (IIASA), Laxenburg (Austria); Biberacher, M. [Research Studios Austria AG (RSA), Salzburg (Austria)

    2013-07-01

    In the framework of the EU FP7 project EnerGEO (Earth Observations for Monitoring and Assessment of the Environmental Impact of Energy Use) sustainable energy potentials for forest and agricultural areas were estimated by applying three different model approaches. Firstly, the Biosphere Energy Transfer Hydrology (BETHY/DLR) model was applied to assess agricultural and forest biomass increases on a regional scale with the extension to grassland. Secondly, the EPIC (Environmental Policy Integrated Climate) - a cropping systems simulation model - was used to estimate grain yields on a global scale and thirdly the Global Forest Model (G4M) was used to estimate global woody biomass harvests and stock. The general objective of the biomass pilot is to implement the observational capacity for using biomass as an important current and future energy resource. The scope of this work was to generate biomass energy potentials for locations on the globe and to validate these data. Therefore, the biomass pilot was focused to use historical and actual remote sensing data as input data for the models. For validation purposes, forest biomass maps for 1987 and 2002 for Germany (Bundeswaldinventur (BWI-2)) and 2001 and 2008 for Austria (Austrian Forest Inventory (AFI)) were prepared as reference. (orig.)

  17. Exact Solutions of Generalized Modified Boussinesq, Kuramoto-Sivashinsky, and Camassa-Holm Equations via Double Reduction Theory

    Directory of Open Access Journals (Sweden)

    Zulfiqar Ali

    2013-01-01

    Full Text Available We find exact solutions of the Generalized Modified Boussinesq (GMB equation, the Kuromoto-Sivashinsky (KS equation the and, Camassa-Holm (CH equation by utilizing the double reduction theory related to conserved vectors. The fourth order GMB equation involves the arbitrary function and mixed derivative terms in highest derivative. The partial Noether’s approach yields seven conserved vectors for GMB equation and one conserved for vector KS equation. Due to presence of mixed derivative term the conserved vectors for GMB equation derived by the Noether like theorem do not satisfy the divergence relationship. The extra terms that constitute the trivial part of conserved vectors are adjusted and the resulting conserved vectors satisfy the divergence property. The double reduction theory yields two independent solutions and one reduction for GMB equation and one solution for KS equation. For CH equation two independent solutions are obtained elsewhere by double reduction theory with the help of conserved Vectors.

  18. On the Constitution and the Constitutions in Contemporary Egypt (2011-2014: Analysis and Early Thoughts

    Directory of Open Access Journals (Sweden)

    José Carlos Castañeda Reyes

    2016-01-01

    world witnessed, a testament to what massive popular participation can attain. We believe the Constitution has true potential to guide the forces of change in the country. Therefore, the struggle for “bread, freedom, social justice and human dignity” will continue and is actually continuing in the Nile country via constitutional and non-constitutional means.

  19. Fusion characterization of biomass ash

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Teng [State Key Laboratory ofMultiphase Complex Systems, Institute of Process Engineering, Chinese Academy of Sciences, No. 1 Zhongguancun North Second Street, Beijing 100190 (China); Sino-Danish Center for Education and Research, Beijing, 100190 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Fan, Chuigang; Hao, Lifang [State Key Laboratory ofMultiphase Complex Systems, Institute of Process Engineering, Chinese Academy of Sciences, No. 1 Zhongguancun North Second Street, Beijing 100190 (China); Li, Songgeng, E-mail: sgli@ipe.ac.cn [State Key Laboratory ofMultiphase Complex Systems, Institute of Process Engineering, Chinese Academy of Sciences, No. 1 Zhongguancun North Second Street, Beijing 100190 (China); Song, Wenli [State Key Laboratory ofMultiphase Complex Systems, Institute of Process Engineering, Chinese Academy of Sciences, No. 1 Zhongguancun North Second Street, Beijing 100190 (China); Lin, Weigang [State Key Laboratory ofMultiphase Complex Systems, Institute of Process Engineering, Chinese Academy of Sciences, No. 1 Zhongguancun North Second Street, Beijing 100190 (China); Department of Chemical and Biochemical Engineering, Technical University of Denmark, 2800 Kgs. Lyngby (Denmark)

    2016-08-20

    Highlights: • A novel method is proposed to analyze fusion characteristics of biomass ash. • T{sub m} can represent the severe melting temperature of biomass ash. • Compared with AFT, TMA is the better choice to analyze the fusion characteristics of biomass ash. - Abstract: The ash fusion characteristics are important parameters for thermochemical utilization of biomass. In this research, a method for measuring the fusion characteristics of biomass ash by Thermo-mechanical Analyzer, TMA, is described. The typical TMA shrinking ratio curve can be divided into two stages, which are closely related to ash melting behaviors. Several characteristics temperatures based on the TMA curves are used to assess the ash fusion characteristics. A new characteristics temperature, T{sub m}, is proposed to represent the severe melting temperature of biomass ash. The fusion characteristics of six types of biomass ash have been measured by TMA. Compared with standard ash fusibility temperatures (AFT) test, TMA is more suitable for measuring the fusion characteristics of biomass ash. The glassy molten areas of the ash samples are sticky and mainly consist of K-Ca-silicates.

  20. Improving estimation of tree carbon stocks by harvesting aboveground woody biomass within airborne LiDAR flight areas

    Science.gov (United States)

    Colgan, M.; Asner, G. P.; Swemmer, A. M.

    2011-12-01

    The accurate estimation of carbon stored in a tree is essential to accounting for the carbon emissions due to deforestation and degradation. Airborne LiDAR (Light Detection and Ranging) has been successful in estimating aboveground carbon density (ACD) by correlating airborne metrics, such as canopy height, to field-estimated biomass. This latter step is reliant on field allometry which is applied to forest inventory quantities, such as stem diameter and height, to predict the biomass of a given tree stem. Constructing such allometry is expensive, time consuming, and requires destructive sampling. Consequently, the sample sizes used to construct such allometry are often small, and the largest tree sampled is often much smaller than the largest in the forest population. The uncertainty resulting from these sampling errors can lead to severe biases when the allometry is applied to stems larger than those harvested to construct the allometry, which is then subsequently propagated to airborne ACD estimates. The Kruger National Park (KNP) mission of maintaining biodiversity coincides with preserving ecosystem carbon stocks. However, one hurdle to accurately quantifying carbon density in savannas is that small stems are typically harvested to construct woody biomass allometry, yet they are not representative of Kruger's distribution of biomass. Consequently, these equations inadequately capture large tree variation in sapwood/hardwood composition, root/shoot/leaf allocation, branch fall, and stem rot. This study eliminates the "middleman" of field allometry by directly measuring, or harvesting, tree biomass within the extent of airborne LiDAR. This enables comparisons of field and airborne ACD estimates, and also enables creation of new airborne algorithms to estimate biomass at the scale of individual trees. A field campaign was conducted at Pompey Silica Mine 5km outside Kruger National Park, South Africa, in Mar-Aug 2010 to harvest and weigh tree mass. Since

  1. Biomass power in transition

    Energy Technology Data Exchange (ETDEWEB)

    Marshall, D.K. [Zurn/NEPCO, Redmond, WA (United States)

    1996-12-31

    Electricity production from biomass fuel has been hailed in recent years as an environmentally acceptable energy source that delivers on its promise of economically viable renewable energy. A Wall Street Journal article from three years ago proclaimed wood to be {open_quotes}moving ahead of costly solar panels and wind turbines as the leading renewable energy alternative to air-fouling fossils fuels and scary nuclear plants.{close_quotes} Biomass fuel largely means wood; about 90% of biomass generated electricity comes from burning waste wood, the remainder from agricultural wastes. Biomass power now faces an uncertain future. The maturing of the cogeneration and independent power plant market, restructuring of the electric industry, and technological advances with power equipment firing other fuels have placed biomass power in a competitive disadvantage with other power sources.

  2. A constitutive model for the forces of a magnetic bearing including eddy currents

    Science.gov (United States)

    Taylor, D. L.; Hebbale, K. V.

    1993-01-01

    A multiple magnet bearing can be developed from N individual electromagnets. The constitutive relationships for a single magnet in such a bearing is presented. Analytical expressions are developed for a magnet with poles arranged circumferencially. Maxwell's field equations are used so the model easily includes the effects of induced eddy currents due to the rotation of the journal. Eddy currents must be included in any dynamic model because they are the only speed dependent parameter and may lead to a critical speed for the bearing. The model is applicable to bearings using attraction or repulsion.

  3. Assessing the uncertainty of forest carbon estimates using the FVS family of diameter increment equations

    Science.gov (United States)

    Matthew B. Russell; Aaron R. Weiskittel; Anthony W. D’Amato

    2012-01-01

    Serving as a carbon (C) accounting tool, the Forest Vegetation Simulator (FVS) is widely used by forest managers and researchers to forecast future forest C stocks. Assessments of the uncertainty that FVS equations provide in terms of their ability to accurately project forest biomass and C would seemingly differ, depending on the region and scale of interest to the...

  4. The constitutional court review of judicial decisions

    Directory of Open Access Journals (Sweden)

    Stojanović Dragan M.

    2016-01-01

    Full Text Available In principle, the constitutional precepts envisage that judicial decisions are not subject to extrajudicial control. However, in the course of deciding on constitutional complaints, the Constitutional Court reviews the compliance of individual legal acts and actions of state authorities with the Constitution, including court decisions on cases involving the constitutionally guaranteed rights. Hence, in order to eliminate tension or even contradiction between the constitutional precepts, the constitutional review of judicial decisions should be considered as a special form of judicial control, regardless of the fact that the Constitutional Court is not part of the judicial structure in the strict organizational sense. Thus, unlike the cases where the Court is involved in the normative control of the applicable law, in the process of reviewing judicial decision of lower courts the constitutional judiciary acts in the capacity of a specific judicial authority. According to another possible interpretation of the aforementioned constitutional norms, the direct constitutional protection of the constitutionally guaranteed rights may only be pursued in the process of reviewing individual legal acts and actions of state authorities, but not by pursuing a judicial review of court decisions which the Constitutional Court has no jurisdiction to decide upon. Thus, the dogma of judicial independence would prevail over the dogma of direct protection of fundamental rights. The third interpretation of this relationship maintains that that judicial decisions may be subject to control but, in this specific case, the Constitutional Court may only issue an opinion (a statement rather than a binding decision which would cancel the lower court judgment. Then, it is up to the judicial authorities of the lower instance to adjust their judicial decision, which in the opinion of the Constitutional Court constitutes a violation of the constitutionally guaranteed rights

  5. Improvement of biomass production and glucoamylase activity by Candida famata using factorial design.

    Science.gov (United States)

    Mosbah, Habib; Aissa, Imen; Hassad, Nahla; Farh, Dhaker; Bakhrouf, Amina; Achour, Sami

    2016-07-01

    To improve biomass production and glucoamylase activity (GA) by Candida famata, culture conditions were optimized. A 2(3) full factorial design (FFD) with a response surface model was used to evaluate the effects and interactions of pH (X1 ), time of cultivation (X2 ), and starch concentration (X3 ) on the biomass production and enzyme activity. A total of 16 experiments were conducted toward the construction of an empiric model and a first-order equation. It was found that all factors (X1 , X2 , and X3 ) and their interactions were significant at a certain confidence level (P production and GA of C. famata. Under this optimized medium, the experimental biomass production and GA obtained were 1.8 ± 0.54 g/L and 0.078 ± 0.012 µmol/L/Min, about 1.5- and 1.8-fold, respectively, higher than those in basal medium. The (R(2) ) coefficients obtained were 0.997 and 0.990, indicating an adequate degree of reliability in the model. Approximately 99% of validity of the predicted value was achieved. © 2015 International Union of Biochemistry and Molecular Biology, Inc.

  6. Carbon, energy and forest biomass: new opportunities and needs for forest management in Italy

    Directory of Open Access Journals (Sweden)

    2005-01-01

    Full Text Available Forest biomass provides a relevant fraction of world energy needs, not only in developing Countries. In Italy, several factors are presently contributing to a new interest for this resource, ranging from regulatory quotas for renewables to the increasing price of fossil fuel to the emergence of a European carbon stock exchange. This focus on renewable resources constitutes an important opportunity for the forest sector and for society by and large, but because of the potential dimensions of the emerging market it also requires new planning instruments, in order to avoid a sudden and widespread resumption of coppice management and a reduction of standing carbon stock in forest ecosystems, which would run contrary to the objectives of the Kyoto Protocol. An example of the future demand for biomasses in Central Italy is presented, based on the possible use of fuelwood in new coal-fired power plants by the 'co-firing' technology.

  7. Forest biomass carbon stocks and variation in Tibet’s carbon-dense forests from 2001 to 2050

    Science.gov (United States)

    Sun, Xiangyang; Wang, Genxu; Huang, Mei; Chang, Ruiying; Ran, Fei

    2016-01-01

    Tibet’s forests, in contrast to China’s other forests, are characterized by primary forests, high carbon (C) density and less anthropogenic disturbance, and they function as an important carbon pool in China. Using the biomass C density data from 413 forest inventory sites and a spatial forest age map, we developed an allometric equation for the forest biomass C density and forest age to assess the spatial biomass C stocks and variation in Tibet’s forests from 2001 to 2050. The results indicated that the forest biomass C stock would increase from 831.1 Tg C in 2001 to 969.4 Tg C in 2050, with a net C gain of 3.6 Tg C yr−1 between 2001 and 2010 and a decrease of 1.9 Tg C yr−1 between 2040 and 2050. Carbon tends to allocate more in the roots of fir forests and less in the roots of spruce and pine forests with increasing stand age. The increase of the biomass carbon pool does not promote significant augmentation of the soil carbon pool. Our findings suggest that Tibet’s mature forests will remain a persistent C sink until 2050. However, afforestation or reforestation, especially with the larger carbon sink potential forest types, such as fir and spruce, should be carried out to maintain the high C sink capacity. PMID:27703215

  8. Solid biomass barometer

    International Nuclear Information System (INIS)

    Anon.

    2011-01-01

    The primary energy production from solid biomass in the European Union reached 79.3 Mtoe in 2010 which implies a growth rate of 8% between 2009 and 2010. The trend, which was driven deeper by Europe's particularly cold winter of 2009-2010, demonstrates that the economic down-turn failed to weaken the member states' efforts to structure the solid biomass sector. Heat consumption rose sharply: the volume of heat sold by heating networks increased by 18% and reached 6.7 Mtoe and if we consider the total heat consumption (it means with and without recovery via heating networks) the figure is 66 Mtoe in 2010, which amounts to 10.1% growth. The growth of electricity production continued through 2010 (8.3% up on 2009) and rose to 67 TWh but at a slower pace than in 2009 (when it rose by 11.3% on 2008). The situation of the main producer countries: Sweden, Finland, Germany and France is reviewed. It appears that cogeneration unit manufacturers and biomass power plant constructors are the main beneficiaries of the current biomass energy sector boom. There is a trend to replace coal-fired plants that are either obsolete or near their end of life with biomass or multi-fuel plants. These opportunities will enable the industry to develop and further exploit new technologies such as gasification, pyrolysis and torrefaction which will enable biomass to be turned into bio-coal. (A.C.)

  9. Biomass for bioenergy

    DEFF Research Database (Denmark)

    Bentsen, Niclas Scott

    Across the range of renewable energy resources, bioenergy is probably the most complex, as using biomass to support energy services ties into a number of fields; climate change, food production, rural development, biodiversity and environmental protection. Biomass offer several options...... for displacing fossil resources and is perceived as one of the main pillars of a future low-carbon or no-carbon energy supply. However, biomass, renewable as it is, is for any relevant, time horizon to be considered a finite resource as it replenishes at a finite rate. Conscientious stewardship of this finite...... the undesirable impacts of bioenergy done wrong. However, doing bioenergy right is a significant challenge due to the ties into other fields of society. Fundamentally plant biomass is temporary storage of solar radiation energy and chemically bound energy from nutrients. Bioenergy is a tool to harness solar...

  10. Yield prediction of young black locust (Robinia pseudoacacia L. plantations for woody biomass production using allometric relations

    Directory of Open Access Journals (Sweden)

    Christian Böhm

    2013-12-01

    Full Text Available Black locust (Robinia pseudoacacia L. is an increasingly popular tree species for the production of woody biomass for bioenergy generation with short rotation coppices. Due to its potential to produce large amounts of biomass yields even under unfavourable growth conditions, this tree species is especially suitable for marginal sites, such as can be found in the post mining area of NE-Germany. Current research aims to reliably predict the yield potential of black locust short rotation coppices, but suffers from a lack of sufficient exact allometric functions until recently. This is especially true for the early growth years, which are of special importance for short rotation coppices. The objective of this study was to develop allometric equations based on tree height and shoot basal diameter (SBD for estimating yields of young black locust plantations. Therefore, dendrometric data were collected in a two, three, four and fourteen years old black locust short rotation forest located in the reclamation area of an opencast-lignite mining area in the Lower Lusatian region (Germany and used for equation developing. Until measurement, none of the plantations had been harvested. Closed correlations between SBD and tree height were observed, as well as between these parameters and single tree mass. The scattering of single tree masses could be explained slightly better by the SBD than by the tree height. In the year before a harvest an even better prediction probability of woody biomass was obtainable when both parameters were simultaneously interrelated with the single tree mass. The results illustrate that the woody above ground biomass of young black locust plantations can be estimated sufficiently precisely based on the easy determinable parameters tree height and particularly SBD.

  11. Biomass in Germany

    International Nuclear Information System (INIS)

    Chapron, Thibaut

    2014-01-01

    This document provides, first, an overview of biomass industry in Germany: energy consumption and renewable energy production, the French and German electricity mix, the 2003-2013 evolution of renewable electricity production and the 2020 forecasts, the biomass power plants, plantations, biofuels production and consumption in Germany. Then, the legal framework of biofuels development in Germany is addressed (financial incentives, tariffs, direct electricity selling). Next, a focus is made on biogas production both in France and in Germany (facilities, resources). Finally, the French-German cooperation in the biomass industry and the research actors are presented

  12. Electricity from biomass

    International Nuclear Information System (INIS)

    Price, B.

    1998-11-01

    Electricity from biomass assesses the potential of biomass electricity for displacing other more polluting power sources and providing a relatively clean and ecologically friendly source of energy; discusses its environmental and economic effects, while analysing political and institutional initiatives and constraints; evaluates key factors, such as energy efficiency, economics, decentralisation and political repurcussions; considers the processes and technologies employed to produce electricity from biomass; and discusses the full range of incentives offered to producers and potential producers and the far-reaching implications it could have for industry, society and the environment. (author)

  13. Potential availability of urban wood biomass in Michigan: Implications for energy production, carbon sequestration and sustainable forest management in the U.S.A

    International Nuclear Information System (INIS)

    MacFarlane, David W.

    2009-01-01

    Tree and wood biomass from urban areas is a potentially large, underutilized resource viewed in the broader social context of biomass production and utilization. Here, data and analysis from a regional study in a 13-county area of Michigan, U.S.A. are combined with data and analysis from several other studies to examine this potential. The results suggest that urban trees and wood waste offer a modest amount of biomass that could contribute significantly more to regional and national bio-economies than it does at present. Better utilization of biomass from urban trees and wood waste could offer new sources of locally generated wood products and bio-based fuels for power and heat generation, reduce fossil fuel consumption, reduce waste disposal costs and reduce pressure on forests. Although wood biomass generally constitutes a 'carbon-neutral' fuel, burning rather than burying urban wood waste may not have a net positive effect on reducing atmospheric CO 2 levels, because it may reduce a significant long term carbon storage pool. Using urban wood residues for wood products may provide the best balance of economic and environmental values for utilization

  14. Is w≠-1 evidence for a dynamical dark energy equation of state?

    International Nuclear Information System (INIS)

    Avelino, P. P.; Trindade, A. M. M.; Viana, P. T. P.

    2009-01-01

    Current constraints on the dark energy equation of state parameter, w, are expected to be improved by more than 1 order of magnitude in the next decade. If |w-1| > or approx. 0.01 around the present time, but the dark energy dynamics is sufficiently slow, it is possible that future constraints will rule out a cosmological constant while being consistent with a time-independent equation of state parameter. In this paper, we show that although models with such behavior can be constructed, they do require significant fine-tuning. Therefore, if the observed acceleration of the Universe is induced by a dark energy component, then finding w≠-1 would, on its own, constitute very strong evidence for a dynamical dark energy equation of state.

  15. Constitutive behavior and microstructure evolution of the as-extruded AE21 magnesium alloy during hot compression testing

    Energy Technology Data Exchange (ETDEWEB)

    Wang, L.-X. [Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China); Fang, G., E-mail: fangg@tsinghua.edu.cn [Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China); Leeflang, M.A.; Duszczyk, J.; Zhou, J. [Department of Biomechanical Engineering, Delft University of Technology, Mekelweg 2, 2628 CD Delft (Netherlands)

    2015-02-15

    Highlights: • Constitutive equation of magnesium alloy AE21 for hot deformation is established. • Material processing history affects the activation energy for deformation. • Zener-Hollomon parameter is used to distinguish the shapes of flow stress curves. • Kink band plays an important role in causing a concave shape of the flow curve of AE21. - Abstract: Magnesium alloys containing rare earth elements possess improved corrosion resistance and mechanical properties and therefore have great potential for a wide range of applications including biomedical applications. Hot forming is meant not only for shaping but also for microstructure modification and performance enhancement. It is of great importance to define optimum forming conditions on the basis of a fundamental understanding of the response of magnesium alloys to deformation. The present study aimed at characterizing the hot deformation behavior of the as-extruded AE21 magnesium alloy by performing isothermal compression tests over a temperature range of 350-480 °C and a strain rate range of 0.001-10 s{sup -1}. Flow stress data obtained were intended for establishing a constitutive equation, which would be indispensable for the prediction of the response of the material to hot deformation, for example, by means of numerical simulation. The true stress-strain curves obtained from the experiments were analyzed, considering different mechanisms of microstructure evolution operating during compression testing at different stages. The Sellar and Tegart model was used to establish the constitutive equation of the alloy during the steady-state deformation. The differences in activation energy value between the present as-extruded magnesium alloy and other wrought magnesium alloys were found and attributed to materials processing history. The Zener-Hollomon parameter was used to correlate the deformation condition with the response of the material to deformation, reflected in the shape of the true stress

  16. Is torrefaction of polysaccharides-rich biomass equivalent to carbonization of lignin-rich biomass?

    Science.gov (United States)

    Bilgic, E; Yaman, S; Haykiri-Acma, H; Kucukbayrak, S

    2016-01-01

    Waste biomass species such as lignin-rich hazelnut shell (HS) and polysaccharides-rich sunflower seed shell (SSS) were subjected to torrefaction at 300°C and carbonization at 600°C under nitrogen. The structural variations in torrefied and carbonized biomasses were compared. Also, the burning characteristics under dry air and pure oxygen (oxy-combustion) conditions were investigated. It was concluded that the effects of carbonization on HS are almost comparable with the effects of torrefaction on SSS in terms of devolatilization and deoxygenation potentials and the increases in carbon content and the heating value. Consequently, it can be proposed that torrefaction does not provide efficient devolatilization from the lignin-rich biomass while it is relatively more efficient for polysaccharides-rich biomass. Heat-induced variations in biomass led to significant changes in the burning characteristics under both burning conditions. That is, low temperature reactivity of biomass reduced considerably and the burning shifted to higher temperatures with very high burning rates. Copyright © 2015 Elsevier Ltd. All rights reserved.

  17. A stochastic model of multiple scattering of charged particles: process, transport equation and solutions

    International Nuclear Information System (INIS)

    Papiez, L.; Moskvin, V.; Tulovsky, V.

    2001-01-01

    The process of angular-spatial evolution of multiple scattering of charged particles can be described by a special case of Boltzmann integro-differential equation called Lewis equation. The underlying stochastic process for this evolution is the compound Poisson process on the surface of the unit sphere. The significant portion of events that constitute compound Poisson process that describes multiple scattering have diffusional character. This property allows to analyze the process of angular-spatial evolution of multiple scattering of charged particles as combination of soft and hard collision processes and compute appropriately its transition densities. These computations provide a method of the approximate solution to the Lewis equation. (orig.)

  18. Biomass potential

    Energy Technology Data Exchange (ETDEWEB)

    Asplund, D [VTT Energy, Espoo (Finland)

    1997-12-31

    Biomass resources of the industrialised countries are enormous, if only a small fraction of set-aside fields were used for energy crops. Forest resources could also be utilised more efficiently than at present for large-scale energy production. The energy content of the annual net growth of the total wood biomass is estimated to be 180 million toe in Europe without the former USSR, and about 50 million toe of that in the EC area, in 1990. Presently, the harvesting methods of forest biomass for energy production are not yet generally competitive. Among the most promising methods are integrated harvesting methods, which supply both raw material to the industry and wood fuel for energy production. Several new methods for separate harvesting of energy wood are being developed in many countries. (orig.)

  19. Biomass potential

    Energy Technology Data Exchange (ETDEWEB)

    Asplund, D. [VTT Energy, Espoo (Finland)

    1996-12-31

    Biomass resources of the industrialised countries are enormous, if only a small fraction of set-aside fields were used for energy crops. Forest resources could also be utilised more efficiently than at present for large-scale energy production. The energy content of the annual net growth of the total wood biomass is estimated to be 180 million toe in Europe without the former USSR, and about 50 million toe of that in the EC area, in 1990. Presently, the harvesting methods of forest biomass for energy production are not yet generally competitive. Among the most promising methods are integrated harvesting methods, which supply both raw material to the industry and wood fuel for energy production. Several new methods for separate harvesting of energy wood are being developed in many countries. (orig.)

  20. Modeling of biomass pyrolysis

    International Nuclear Information System (INIS)

    Samo, S.R.; Memon, A.S.; Akhund, M.A.

    1995-01-01

    The fuels used in industry and power sector for the last two decades have become expensive. As a result renewable energy source have been emerging increasingly important, of these, biomass appears to be the most applicable in the near future. The pyrolysis of biomass plays a key role amongst the three major and important process generally encountered in a gas producer, namely, pyrolysis, combustion and reduction of combustion products. Each biomass has its own pyrolysis characteristics and this important parameters must be known for the proper design and efficient operation of a gasification system. Thermogravimetric analysis has been widely used to study the devolatilization of solid fuels, such as biomass. It provides the weight loss history of a sample heated at a predetermined rate as a function of time and temperature. This paper presents the experimental results of modelling the weight loss curves of the main biomass components i.e. cellulose, hemicellulose and lignin. Thermogravimetric analysis of main components of biomass showed that pyrolysis is first order reaction. Furthermore pyrolysis of cellulose and hemicelluloe can be regarded as taking place in two stages, for while lignin pyrolysis is a single stage process. This paper also describes the Thermogravimetric Analysis (TGA) technique to predict the weight retained during pyrolysis at any temperature, for number of biomass species, such as cotton stalk, bagasse ad graoundnut shell. (author)

  1. International biomass. International markets of biomass-energy - Public synthesis

    International Nuclear Information System (INIS)

    Gardette, Yves-Marie; Dieckhoff, Lea; Lorne, Daphne; Postec, Gwenael; Cherisey, Hugues de; RANTIEN, Caroline

    2014-11-01

    This publication proposes a synthesis of a study which aimed at analysing the present and future place of wood-energy in the European Union as the main renewable resource used to produce heat and electricity. This study comprised an analysis of European markets of solid biomass and of regulation, case studies on wood-energy producer markets (North America, Eastern Europe, Brazil and Africa), a study of preparation modes (shredding, granulation, roasting) and biomass transport. This study is based on bibliographical searches in national and European sources, and on field data collected by the various bodies involved in this study. This synthesis notably discusses the following issues: solid biomass is the main renewable resource for the EU and has many applications; European objectives for solid biomass by 2020 are very ambitious; markets are becoming international to face the EU's increasing demand; pellet production in North America is strongly increasing; in Europe, eastern European countries are the main exporters; Brazil has an export potential which is still to be confirmed; the African trade with Europe is still in its infancy. Finally, the development perspectives of roasted wood trade are discussed

  2. Specific and generic stem biomass and volume models of tree species in a West African tropical semi-deciduous forest

    DEFF Research Database (Denmark)

    Goussanou, Cédric A.; Guendehou, Sabin; Assogbadjo, Achille E.

    2016-01-01

    The quantification of the contribution of tropical forests to global carbon stocks and climate change mitigation requires availability of data and tools such as allometric equations. This study made available volume and biomass models for eighteen tree species in a semi-deciduous tropical forest...... in West Africa. Generic models were also developed for the forest ecosystem, and basic wood density determined for the tree species. Non-destructive sampling approach was carried out on five hundred and one sample trees to analyse stem volume and biomass. From the modelling of volume and biomass...... enabled to conclude that the non-destructive sampling was a good approach to determining reliable basic wood density. The comparative analysis of species-specific models in this study with selected generic models for tropical forests indicated low probability to identify effective generic models with good...

  3. Natural Gas and Cellulosic Biomass: A Clean Fuel Combination? Determining the Natural Gas Blending Wall in Biofuel Production.

    Science.gov (United States)

    M Wright, Mark; Seifkar, Navid; Green, William H; Román-Leshkov, Yuriy

    2015-07-07

    Natural gas has the potential to increase the biofuel production output by combining gas- and biomass-to-liquids (GBTL) processes followed by naphtha and diesel fuel synthesis via Fischer-Tropsch (FT). This study reflects on the use of commercial-ready configurations of GBTL technologies and the environmental impact of enhancing biofuels with natural gas. The autothermal and steam-methane reforming processes for natural gas conversion and the gasification of biomass for FT fuel synthesis are modeled to estimate system well-to-wheel emissions and compare them to limits established by U.S. renewable fuel mandates. We show that natural gas can enhance FT biofuel production by reducing the need for water-gas shift (WGS) of biomass-derived syngas to achieve appropriate H2/CO ratios. Specifically, fuel yields are increased from less than 60 gallons per ton to over 100 gallons per ton with increasing natural gas input. However, GBTL facilities would need to limit natural gas use to less than 19.1% on a LHV energy basis (7.83 wt %) to avoid exceeding the emissions limits established by the Renewable Fuels Standard (RFS2) for clean, advanced biofuels. This effectively constitutes a blending limit that constrains the use of natural gas for enhancing the biomass-to-liquids (BTL) process.

  4. Modified two-fluid model for the two-group interfacial area transport equation

    International Nuclear Information System (INIS)

    Sun Xiaodong; Ishii, Mamoru; Kelly, Joseph M.

    2003-01-01

    This paper presents a modified two-fluid model that is ready to be applied in the approach of the two-group interfacial area transport equation. The two-group interfacial area transport equation was developed to provide a mechanistic constitutive relation for the interfacial area concentration in the two-fluid model. In the two-group transport equation, bubbles are categorized into two groups: spherical/distorted bubbles as Group 1 while cap/slug/churn-turbulent bubbles as Group 2. Therefore, this transport equation can be employed in the flow regimes spanning from bubbly, cap bubbly, slug to churn-turbulent flows. However, the introduction of the two groups of bubbles requires two gas velocity fields. Yet it is not practical to solve two momentum equations for the gas phase alone. In the current modified two-fluid model, a simplified approach is proposed. The momentum equation for the averaged velocity of both Group-1 and Group-2 bubbles is retained. By doing so, the velocity difference between Group-1 and Group-2 bubbles needs to be determined. This may be made either based on simplified momentum equations for both Group-1 and Group-2 bubbles or by a modified drift-flux model

  5. Energy from biomass: An overview

    International Nuclear Information System (INIS)

    Van der Toorn, L.J.; Elliott, T.P.

    1992-01-01

    Attention is paid to the effect of the use of energy from biomass on the greenhouse effect. An overview is given of the aspects of forest plantation, carbon dioxide fixation and energy from biomass, in particular with regard to the potential impact of the use of biomass energy on the speed of accumulation of carbon in the atmosphere. A simple model of the carbon cycle to illustrate the geochemical, biological and antropogenic characteristics of the cycle is presented and briefly discussed. Biomass, which is appropriate for energy applications, can be subdivided into three categories: polysaccharides, vegetable oils, and lignocellulosis. The costs for the latter are discussed. Three important options to use biomass as a commercial energy source are solid fuels, liquid fuels, and power generation. For each option the value of energy (on a large-scale level) is compared to the costs of several types of biomass. Recent evaluation of new techniques show that small biomass conversion plants can realize an electricity efficiency of 40%, with capitalized costs far below comparable conventional biomass conversion plants. One of the policy instruments to stimulate the use of biomass as an energy source is the carbon levy, in which the assumed external costs to reduce carbon dioxide emission are expressed. Political and administrative feasibility are important factors in the decision making with regard to carbon storage and energy plantations. 6 figs

  6. Relativistic dissipative hydrodynamic equations at the second order for multi-component systems with multiple conserved currents

    International Nuclear Information System (INIS)

    Monnai, Akihiko; Hirano, Tetsufumi

    2010-01-01

    We derive the second order hydrodynamic equations for the relativistic system of multi-components with multiple conserved currents by generalizing the Israel-Stewart theory and Grad's moment method. We find that, in addition to the conventional moment equations, extra moment equations associated with conserved currents should be introduced to consistently match the number of equations with that of unknowns and to satisfy the Onsager reciprocal relations. Consistent expansion of the entropy current leads to constitutive equations which involve the terms not appearing in the original Israel-Stewart theory even in the single component limit. We also find several terms which exhibit thermal diffusion such as Soret and Dufour effects. We finally compare our results with those of other existing formalisms.

  7. Predicting Volume and Biomass Change from Multi-Temporal Lidar Sampling and Remeasured Field Inventory Data in Panther Creek Watershed, Oregon, USA

    Directory of Open Access Journals (Sweden)

    Krishna P. Poudel

    2018-01-01

    Full Text Available Using lidar for large-scale forest management can improve operational and management decisions. Using multi-temporal lidar sampling and remeasured field inventory data collected from 78 plots in the Panther Creek Watershed, Oregon, USA, we evaluated the performance of different fixed and mixed models in estimating change in aboveground biomass ( ∆ AGB and cubic volume including top and stump ( ∆ CVTS over a five-year period. Actual values of CVTS and AGB were obtained using newly fitted volume and biomass equations or the equations used by the Pacific Northwest unit of the Forest Inventory and Analysis program. Estimates of change based on fixed and mixed-effect linear models were more accurate than change estimates based on differences in LIDAR-based estimates. This may have been due to the compounding of errors in LIDAR-based estimates over the two time periods. Models used to predict volume and biomass at a given time were, however, more precise than the models used to predict change. Models used to estimate ∆ CVTS were not as accurate as the models employed to estimate ∆ AGB . Final models had cross-validation root mean squared errors as low as 40.90% for ∆ AGB and 54.36% for ∆ CVTS .

  8. ALTENER - Biomass event in Finland

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-12-31

    The publication contains the lectures held in the Biomass event in Finland. The event was divided into two sessions: Fuel production and handling, and Co-combustion and gasification sessions. Both sessions consisted of lectures and the business forum during which the companies involved in the research presented themselves and their research and their equipment. The fuel production and handling session consisted of following lectures and business presentations: AFB-NETT - business opportunities for European biomass industry; Wood waste in Europe; Wood fuel production technologies in EU- countries; new drying method for wood waste; Pellet - the best package for biofuel - a view from the Swedish pelletmarket; First biomass plant in Portugal with forest residue fuel; and the business forum of presentations: Swedish experiences of willow growing; Biomass handling technology; Chipset 536 C Harvester; KIC International. The Co-combustion and gasification session consisted of following lectures and presentations: Gasification technology - overview; Overview of co-combustion technology in Europe; Modern biomass combustion technology; Wood waste, peat and sludge combustion in Enso Kemi mills and UPM-Kymmene Rauma paper mill; Enhanced CFB combustion of wood chips, wood waste and straw in Vaexjoe in Sweden and Grenaa CHP plant in Denmark; Co-combustion of wood waste; Biomass gasification projects in India and Finland; Biomass CFB gasifier connected to a 350 MW{sub t}h steam boiler fired with coal and natural gas - THERMIE demonstration project in Lahti (FI); Biomass gasification for energy production, Noord Holland plant in Netherlands and Arbre Energy (UK); Gasification of biomass in fixed bed gasifiers, Wet cleaning and condensing heat recovery of flue gases; Combustion of wet biomass by underfeed grate boiler; Research on biomass and waste for energy; Engineering and consulting on energy (saving) projects; and Research and development on combustion of solid fuels

  9. ALTENER - Biomass event in Finland

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-12-31

    The publication contains the lectures held in the Biomass event in Finland. The event was divided into two sessions: Fuel production and handling, and Co-combustion and gasification sessions. Both sessions consisted of lectures and the business forum during which the companies involved in the research presented themselves and their research and their equipment. The fuel production and handling session consisted of following lectures and business presentations: AFB-NETT - business opportunities for European biomass industry; Wood waste in Europe; Wood fuel production technologies in EU- countries; new drying method for wood waste; Pellet - the best package for biofuel - a view from the Swedish pelletmarket; First biomass plant in Portugal with forest residue fuel; and the business forum of presentations: Swedish experiences of willow growing; Biomass handling technology; Chipset 536 C Harvester; KIC International. The Co-combustion and gasification session consisted of following lectures and presentations: Gasification technology - overview; Overview of co-combustion technology in Europe; Modern biomass combustion technology; Wood waste, peat and sludge combustion in Enso Kemi mills and UPM-Kymmene Rauma paper mill; Enhanced CFB combustion of wood chips, wood waste and straw in Vaexjoe in Sweden and Grenaa CHP plant in Denmark; Co-combustion of wood waste; Biomass gasification projects in India and Finland; Biomass CFB gasifier connected to a 350 MW{sub t}h steam boiler fired with coal and natural gas - THERMIE demonstration project in Lahti (FI); Biomass gasification for energy production, Noord Holland plant in Netherlands and Arbre Energy (UK); Gasification of biomass in fixed bed gasifiers, Wet cleaning and condensing heat recovery of flue gases; Combustion of wet biomass by underfeed grate boiler; Research on biomass and waste for energy; Engineering and consulting on energy (saving) projects; and Research and development on combustion of solid fuels

  10. ECHR and national constitutional courts

    OpenAIRE

    Nastić, Maja

    2015-01-01

    Comprising fundamental rights and freedoms and establishing the effective control system, the European Convention on Human Rights (ECHR) encroaches upon the area that is traditional reserved for constitutional law. Although built on the doctrine reserved for international treaty law, the Convention goes beyond the traditional boundaries that exist between international and constitutional law. It has gradually infiltrated into the national legal systems. Constitutional courts have had the cruc...

  11. Catalytic routes from biomass to fuels

    DEFF Research Database (Denmark)

    Riisager, Anders

    2014-01-01

    chain unaffected. This presentation will survey the status of biofuels production from different sources, and discuss the sustainability of making transportation fuels from biomass. Furthermore, recently developed chemocatalytic technologies that allow efficient conversion of lignocellulosic biomass...... the chemical industry to find new feasible chemocatalytic routes to convert the components of lignocellulosic plant biomass (green biomass) as well as aquatic biomass (blue biomass) into potential platform chemicals that can replace the fossil based chemicals in order to leave the chemical supply and value...

  12. Biomass Data | Geospatial Data Science | NREL

    Science.gov (United States)

    Biomass Data Biomass Data These datasets detail the biomass resources available in the United Coverage File Last Updated Metadata Biomethane Zip 72.2 MB 10/30/2014 Biomethane.xml Solid Biomass Zip 69.5

  13. The U.S. Constitution in Today's World.

    Science.gov (United States)

    Patrick, John J.

    A comparative study of constitutions and governments in world history is a key to deeper understanding of the U.S. Constitution. While many countries have constitutions, the United States is among a minority of nations in today's world that has a constitutional government. Many nations' constitutions truly guarantee few protections of individual…

  14. Biomass co-firing opportunities and experiences

    Energy Technology Data Exchange (ETDEWEB)

    Lyng, R. [Ontario Power Generation Inc., Niagara Falls, ON (Canada). Nanticoke Generating Station

    2006-07-01

    Biomass co-firing and opportunities in the electricity sector were described in this presentation. Biomass co-firing in a conventional coal plant was first illustrated. Opportunities that were presented included the Dutch experience and Ontario Power Generation's (OPG) plant and production mix. The biomass co-firing program at OPG's Nantucket generating station was presented in three phases. The fuel characteristics of co-firing were identified. Several images and charts of the program were provided. Results and current status of tests were presented along with conclusions of the biomass co-firing program. It was concluded that biomass firing is feasible and following the Dutch example. Biomass firing could considerably expand renewable electricity generation in Ontario. In addition, sufficient biomass exists in Ontario and the United States to support large scale biomass co-firing. Several considerations were offered such as electricity market price for biomass co-firing and intensity targets and credit for early adoption and banking. tabs., figs.

  15. Mapping aboveground woody biomass using forest inventory, remote sensing and geostatistical techniques.

    Science.gov (United States)

    Yadav, Bechu K V; Nandy, S

    2015-05-01

    Mapping forest biomass is fundamental for estimating CO₂ emissions, and planning and monitoring of forests and ecosystem productivity. The present study attempted to map aboveground woody biomass (AGWB) integrating forest inventory, remote sensing and geostatistical techniques, viz., direct radiometric relationships (DRR), k-nearest neighbours (k-NN) and cokriging (CoK) and to evaluate their accuracy. A part of the Timli Forest Range of Kalsi Soil and Water Conservation Division, Uttarakhand, India was selected for the present study. Stratified random sampling was used to collect biophysical data from 36 sample plots of 0.1 ha (31.62 m × 31.62 m) size. Species-specific volumetric equations were used for calculating volume and multiplied by specific gravity to get biomass. Three forest-type density classes, viz. 10-40, 40-70 and >70% of Shorea robusta forest and four non-forest classes were delineated using on-screen visual interpretation of IRS P6 LISS-III data of December 2012. The volume in different strata of forest-type density ranged from 189.84 to 484.36 m(3) ha(-1). The total growing stock of the forest was found to be 2,024,652.88 m(3). The AGWB ranged from 143 to 421 Mgha(-1). Spectral bands and vegetation indices were used as independent variables and biomass as dependent variable for DRR, k-NN and CoK. After validation and comparison, k-NN method of Mahalanobis distance (root mean square error (RMSE) = 42.25 Mgha(-1)) was found to be the best method followed by fuzzy distance and Euclidean distance with RMSE of 44.23 and 45.13 Mgha(-1) respectively. DRR was found to be the least accurate method with RMSE of 67.17 Mgha(-1). The study highlighted the potential of integrating of forest inventory, remote sensing and geostatistical techniques for forest biomass mapping.

  16. Insights into plant cell wall structure, architecture, and integrity using glycome profiling of native and AFEXTM-pre-treated biomass

    Science.gov (United States)

    Pattathil, Sivakumar; Hahn, Michael G.; Dale, Bruce E.; Chundawat, Shishir P. S.

    2015-01-01

    Cell walls, which constitute the bulk of plant biomass, vary considerably in their structure, composition, and architecture. Studies on plant cell walls can be conducted on both native and pre-treated plant biomass samples, allowing an enhanced understanding of these structural and compositional variations. Here glycome profiling was employed to determine the relative abundance of matrix polysaccharides in several phylogenetically distinct native and pre-treated plant biomasses. Eight distinct biomass types belonging to four different subgroups (i.e. monocot grasses, woody dicots, herbaceous dicots, and softwoods) were subjected to various regimes of AFEX™ (ammonia fiber expansion) pre-treatment [AFEX is a trademark of MBI, Lansing (http://www.mbi.org]. This approach allowed detailed analysis of close to 200 cell wall glycan epitopes and their relative extractability using a high-throughput platform. In general, irrespective of the phylogenetic origin, AFEX™ pre-treatment appeared to cause loosening and improved accessibility of various xylan epitope subclasses in most plant biomass materials studied. For most biomass types analysed, such loosening was also evident for other major non-cellulosic components including subclasses of pectin and xyloglucan epitopes. The studies also demonstrate that AFEX™ pre-treatment significantly reduced cell wall recalcitrance among diverse phylogenies (except softwoods) by inducing structural modifications to polysaccharides that were not detectable by conventional gross composition analyses. It was found that monitoring changes in cell wall glycan compositions and their relative extractability for untreated and pre-treated plant biomass can provide an improved understanding of variations in structure and composition of plant cell walls and delineate the role(s) of matrix polysaccharides in cell wall recalcitrance. PMID:25911738

  17. Transitional processes: Territorial organization of authorities and the future constitution of Serbia comparative analysis of five constitutional models

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    Despotović Ljubiša M.

    2004-01-01

    Full Text Available In this paper the authors give a comparative analysis of territorial organization of authorities in five constitutional models for Serbia. The paper consists of the following chapters: Introduction, Outline of the Constitution of Kingdom of Serbia, Basic Principles of the New Constitution of Serbia - DSS, Outline of Constitution of Republic of Serbia - DS Constitutional Solutions for Serbia - BCLJP, Project of Constitution of Republic of Serbia - Forum iuris, Conclusion. The analysis of territorial organization of authorities has been seen in the context of the processes of transition and archiving the important principles of civil society and civil autonomies.

  18. BIOMASS AND NUTRIENTS IN A 27 YEARS Pinus taeda L. STAND CLEAR CUTTING IN CAMBARÁ DO SUL, RS STATE

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    Mauro Valdir Schumacher

    2013-06-01

    Full Text Available http://dx.doi.org/10.5902/198050989278This study was conducted in a 27 year Pinus taeda stand in Cambará do Sul, Rio Grande do Sul state and aimed to estimate the biomass production, nutrient stock and to evaluate the nutritional impact in different forest harvesting intensities. Biomass was estimated through regression equation adjustments, with the cut of 15 trees distributed in 5 diametric classes. Nutrients stock was obtained through the product between the average content of nutrients in each biomass component and the number of trees per diametric class per hectare. Pinus taeda above ground biomass was estimated in 266.08 Mg ha-1, being 69.1% of wood, 17.1 of live branches, 6.7% of bark, 3.8% of dead branches and 3.4% of needles. Nutrients stock in biomass (kg ha-1 was estimated in: 511.96 of N, 44.39 of P, 174.27 of K, 310.77 of Ca, 103.80 of Mg, 115.36 of S, 2.94 of B, 0.62 of Cu, 17.34 of Fe, 36.70 of Mn and 4.46 of Zn. Nutrients stock relative distribution in Pinus taeda biomass components showed the following sequence: wood (43.6%, live branches (24.8%, needles (19.0%, bark (8.7% and dead branches (3.9%. Total above ground biomass harvest, when compared to only wood removal, leads to nutrients export increase that can vary from 58.0% to 127.4%, depending on the chemical element, while biomass removal increases 40.8%.

  19. Biomass feedstock analyses

    Energy Technology Data Exchange (ETDEWEB)

    Wilen, C.; Moilanen, A.; Kurkela, E. [VTT Energy, Espoo (Finland). Energy Production Technologies

    1996-12-31

    The overall objectives of the project `Feasibility of electricity production from biomass by pressurized gasification systems` within the EC Research Programme JOULE II were to evaluate the potential of advanced power production systems based on biomass gasification and to study the technical and economic feasibility of these new processes with different type of biomass feed stocks. This report was prepared as part of this R and D project. The objectives of this task were to perform fuel analyses of potential woody and herbaceous biomasses with specific regard to the gasification properties of the selected feed stocks. The analyses of 15 Scandinavian and European biomass feed stock included density, proximate and ultimate analyses, trace compounds, ash composition and fusion behaviour in oxidizing and reducing atmospheres. The wood-derived fuels, such as whole-tree chips, forest residues, bark and to some extent willow, can be expected to have good gasification properties. Difficulties caused by ash fusion and sintering in straw combustion and gasification are generally known. The ash and alkali metal contents of the European biomasses harvested in Italy resembled those of the Nordic straws, and it is expected that they behave to a great extent as straw in gasification. Any direct relation between the ash fusion behavior (determined according to the standard method) and, for instance, the alkali metal content was not found in the laboratory determinations. A more profound characterisation of the fuels would require gasification experiments in a thermobalance and a PDU (Process development Unit) rig. (orig.) (10 refs.)

  20. Conversion analysis of a cylindrical biomass particle with a DEM-CFD coupling approach

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    Mohammad Mohseni

    2017-09-01

    Full Text Available Biomass as a renewable energy source has attracted more attention nowadays due to ecological and economical benefits. The main objective of this work is studying the biomass conversion with employing a DEM-CFD coupling approach. In this model, the solid particulates are considered as discrete elements coupled via heat, mass and momentum transfer to the surrounding gas as continuous phase. That is, a comprehensive three-dimensional numerical model is developed and applied to investigate the complex phenomena taking place during biomass conversion in a reactor. In this case, the physical and chemical processes as heat-up, drying, pyrolysis, gasification and combustion are taken into account based on the relevant homogeneous and heterogeneous reactions. This platform predicts the motion of discrete particles based on the newton's equations of motion; and the thermodynamic state of each particle is extended according to the related algorithms. The thermodynamic state estimates the temperature and species distributions inside the particle due to external heat sources and chemical reactions. The reaction rates are described with Arrhenius model, and the reactions in the gas phase are modeled using Partially Stirred Reactor (PaSR model with the standard k−ϵ turbulent model. The conductive and radiative heat transfer between particles as well as convective heat transfer between particles and gas phase are also observed. Due to layered behavior of biomass materials, the shape of particle is considered as cylindrical rather than spherical to predict more realistic results. In order to improve the numerical modeling of biomass conversion, a shrinkage model is also developed and validated with experimental data in literature.