Maquer, Ghislain; Musy, Sarah N; Wandel, Jasmin; Gross, Thomas; Zysset, Philippe K
2015-06-01
As our population ages, more individuals suffer from osteoporosis. This disease leads to impaired trabecular architecture and increased fracture risk. It is essential to understand how morphological and mechanical properties of the cancellous bone are related. Morphology-elasticity relationships based on bone volume fraction (BV/TV) and fabric anisotropy explain up to 98% of the variation in elastic properties. Yet, other morphological variables such as individual trabeculae segmentation (ITS) and trabecular bone score (TBS) could improve the stiffness predictions. A total of 743 micro-computed tomography (μCT) reconstructions of cubic trabecular bone samples extracted from femur, radius, vertebrae, and iliac crest were analyzed. Their morphology was assessed via 25 variables and their stiffness tensor (CFE) was computed from six independent load cases using micro finite element (μFE) analyses. Variance inflation factors were calculated to evaluate collinearity between morphological variables and decide upon their inclusion in morphology-elasticity relationships. The statistically admissible morphological variables were included in a multiple linear regression model of the dependent variable CFE. The contribution of each independent variable was evaluated (ANOVA). Our results show that BV/TV is the best determinant of CFE(r(2) adj = 0.889), especially in combination with fabric anisotropy (r(2) adj = 0.968). Including the other independent predictors hardly affected the amount of variance explained by the model (r(2) adj = 0.975). Across all anatomical sites, BV/TV explained 87% of the variance of the bone elastic properties. Fabric anisotropy further described 10% of the bone stiffness, but the improvement in variance explanation by adding other independent factors was marginal (variables do not bring any further contribution. These overall conclusions remain to be confirmed for specific bone diseases and postelastic properties.
Energy Technology Data Exchange (ETDEWEB)
Ostebee, Heath Michael; Ziminsky, Willy Steve; Johnson, Thomas Edward; Keener, Christopher Paul
2017-01-17
The present application provides a variable volume combustor for use with a gas turbine engine. The variable volume combustor may include a liner, a number of micro-mixer fuel nozzles positioned within the liner, and a linear actuator so as to maneuver the micro-mixer fuel nozzles axially along the liner.
Forghani-Tehrani, Pezhman; Karimipour, Arash; Afrand, Masoud; Mousavi, Sayedali
2017-01-01
Nanofluid flow and heat transfer composed of water-silver nanoparticles is investigated numerically inside a microchannel. Finite volume approach (FVM) is applied and the effects of gravity are ignored. The whole length of Microchannel is considered in three sections as l1=l3=0.151 and l2=0.71. The linear variable heat flux affects the microchannel wall in the length of l2 while a magnetic field with strength of B0 is considered over the whole domain of it. The influences of different values of Hartmann number (Ha=0, 10, 20), volume fraction of the nanoparticles (ɸ=0, 0.02, 0.04) and Reynolds number (Re=10, 50, 200) on the hydrodynamic and thermal properties of flow are reported. The investigation of slip velocity variations under the effects of a magnetic field are presented for the first time (to the best knowledge of author) while the non-dimensional slip coefficient are selected as B=0.01, 0.05, 0.1 at different states.
Fractional Action Cosmology with Variable Order Parameter
El-Nabulsi, Rami Ahmad
2017-04-01
Fractional action cosmology with variable order parameter was constructed in this paper. Starting from a fractional weighted action which generalizes the fractional actionlike variational approach, a large number of cosmological dynamical equations are obtained depending on the mathematical type of the fractional order parameter. Through this paper, we selected two independent types which result on a number of cosmological scenarios and we discussed their dynamical consequences. It was observed that the present fractional cosmological formalism holds a large family of solutions and offers new features not found in the standard formalism and in many fundamental research papers.
Fractional Action Cosmology with Variable Order Parameter
El-Nabulsi, Rami Ahmad
2017-01-01
Fractional action cosmology with variable order parameter was constructed in this paper. Starting from a fractional weighted action which generalizes the fractional actionlike variational approach, a large number of cosmological dynamical equations are obtained depending on the mathematical type of the fractional order parameter. Through this paper, we selected two independent types which result on a number of cosmological scenarios and we discussed their dynamical consequences. It was observed that the present fractional cosmological formalism holds a large family of solutions and offers new features not found in the standard formalism and in many fundamental research papers.
Absorbed fractions for electrons in ellipsoidal volumes
Amato, E.; Lizio, D.; Baldari, S.
2011-01-01
We applied a Monte Carlo simulation in Geant4 in order to calculate the absorbed fractions for monoenergetic electrons in the energy interval between 10 keV and 2 MeV, uniformly distributed in ellipsoids made from soft tissue. For each volume, we simulated a spherical shape, four oblate and four prolate ellipsoids, and one scalene shape. For each energy and for every geometrical configuration, an analytical relationship between the absorbed fraction and a 'generalized radius' was found, and the dependence of the fit parameters from electron energy is discussed and fitted by proper parametric functions. With the proposed formulation, the absorbed fraction for electrons in the 10-2000 keV energy range can be calculated for all volumes and for every ellipsoidal shape of practical interest. This method can be directly applied to evaluation of the absorbed fraction from the radionuclide emission of monoenergetic electrons, such as Auger or conversion electrons. The average deposited energy per disintegration in the case of extended beta spectra can be evaluated through integration. Two examples of application to a pure beta emitter such as 90Y and to 131I, whose emission include monoenergetic and beta electrons plus gamma photons, are presented. This approach represent a generalization of our previous studies, allowing a comprehensive treatment of absorbed fractions from electron and photon sources uniformly distributed in ellipsoidal volumes of any ellipticity and volume, in the whole range of practical interest for internal dosimetry in nuclear medicine applications, as well as in radiological protection estimations of doses from an internal contamination.
Variable-order fuzzy fractional PID controller.
Liu, Lu; Pan, Feng; Xue, Dingyu
2015-03-01
In this paper, a new tuning method of variable-order fractional fuzzy PID controller (VOFFLC) is proposed for a class of fractional-order and integer-order control plants. Fuzzy logic control (FLC) could easily deal with parameter variations of control system, but the fractional-order parameters are unable to change through this way and it has confined the effectiveness of FLC. Therefore, an attempt is made in this paper to allow all the five parameters of fractional-order PID controller vary along with the transformation of system structure as the outputs of FLC, and the influence of fractional orders λ and μ on control systems has been investigated to make the fuzzy rules for VOFFLC. Four simulation results of different plants are shown to verify the availability of the proposed control strategy.
Variable Order and Distributed Order Fractional Operators
Lorenzo, Carl F.; Hartley, Tom T.
2002-01-01
Many physical processes appear to exhibit fractional order behavior that may vary with time or space. The continuum of order in the fractional calculus allows the order of the fractional operator to be considered as a variable. This paper develops the concept of variable and distributed order fractional operators. Definitions based on the Riemann-Liouville definitions are introduced and behavior of the operators is studied. Several time domain definitions that assign different arguments to the order q in the Riemann-Liouville definition are introduced. For each of these definitions various characteristics are determined. These include: time invariance of the operator, operator initialization, physical realization, linearity, operational transforms. and memory characteristics of the defining kernels. A measure (m2) for memory retentiveness of the order history is introduced. A generalized linear argument for the order q allows the concept of "tailored" variable order fractional operators whose a, memory may be chosen for a particular application. Memory retentiveness (m2) and order dynamic behavior are investigated and applications are shown. The concept of distributed order operators where the order of the time based operator depends on an additional independent (spatial) variable is also forwarded. Several definitions and their Laplace transforms are developed, analysis methods with these operators are demonstrated, and examples shown. Finally operators of multivariable and distributed order are defined in their various applications are outlined.
Variable Order Fractional Variational Calculus for Double Integrals
Odzijewicz, Tatiana; Malinowska, Agnieszka B.; Torres, Delfim F. M.
2012-01-01
We introduce three types of partial fractional operators of variable order. An integration by parts formula for partial fractional integrals of variable order and an extension of Green's theorem are proved. These results allow us to obtain a fractional Euler-Lagrange necessary optimality condition for variable order two-dimensional fractional variational problems.
Variable Order Fractional Variational Calculus for Double Integrals
Odzijewicz, Tatiana; Malinowska, Agnieszka B.; Torres, Delfim F. M.
2012-01-01
We introduce three types of partial fractional operators of variable order. An integration by parts formula for partial fractional integrals of variable order and an extension of Green's theorem are proved. These results allow us to obtain a fractional Euler-Lagrange necessary optimality condition for variable order two-dimensional fractional variational problems.
VOFI - A library to initialize the volume fraction scalar field
Bnà, S.; Manservisi, S.; Scardovelli, R.; Yecko, P.; Zaleski, S.
2016-03-01
The VOFI library has been developed to accurately calculate the volume fraction field demarcated by implicitly-defined fluid interfaces in Cartesian grids with cubic cells. The method enlists a number of algorithms to compute the integration limits and the local height function, that is the integrand of a double Gauss-Legendre integration with a variable number of nodes. Tests in two and three dimensions are presented to demonstrate the accuracy of the method and are provided in the software distribution with C/C++ and FORTRAN interfaces.
Mendoza, Carlos I; Santamaría-Holek, I
2009-01-28
We propose a simple and general model accounting for the dependence of the viscosity of a hard sphere suspension at arbitrary volume fractions. The model constitutes a continuum-medium description based on a recursive-differential method where correlations between the spheres are introduced through an effective volume fraction. In contrast to other differential methods, the introduction of the effective volume fraction as the integration variable implicitly considers interactions between the spheres of the same recursive stage. The final expression for the viscosity scales with this effective volume fraction, which allows constructing a master curve that contains all the experimental situations considered. The agreement of our expression for the viscosity with experiments at low- and high-shear rates and in the high-frequency limit is remarkable for all volume fractions.
Numerical simulation for SI model with variable-order fractional
Directory of Open Access Journals (Sweden)
mohamed mohamed
2016-04-01
Full Text Available In this paper numerical studies for the variable-order fractional delay differential equations are presented. Adams-Bashforth-Moulton algorithm has been extended to study this problem, where the derivative is defined in the Caputo variable-order fractional sense. Special attention is given to prove the error estimate of the proposed method. Numerical test examples are presented to demonstrate utility of the method. Chaotic behaviors are observed in variable-order one dimensional delayed systems.
Fractional Langevin model of gait variability
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Latka Miroslaw
2005-08-01
Full Text Available Abstract The stride interval in healthy human gait fluctuates from step to step in a random manner and scaling of the interstride interval time series motivated previous investigators to conclude that this time series is fractal. Early studies suggested that gait is a monofractal process, but more recent work indicates the time series is weakly multifractal. Herein we present additional evidence for the weakly multifractal nature of gait. We use the stride interval time series obtained from ten healthy adults walking at a normal relaxed pace for approximately fifteen minutes each as our data set. A fractional Langevin equation is constructed to model the underlying motor control system in which the order of the fractional derivative is itself a stochastic quantity. Using this model we find the fractal dimension for each of the ten data sets to be in agreement with earlier analyses. However, with the present model we are able to draw additional conclusions regarding the nature of the control system guiding walking. The analysis presented herein suggests that the observed scaling in interstride interval data may not be due to long-term memory alone, but may, in fact, be due partly to the statistics.
Lamb Wave Assessment of Fiber Volume Fraction in Composites
Seale, Michael D.; Smith, Barry T.; Prosser, W. H.; Zalameda, Joseph N.
1998-01-01
Among the various techniques available, ultrasonic Lamb waves offer a convenient method of examining composite materials. Since the Lamb wave velocity depends on the elastic properties of a material, an effective tool exists to evaluate composites by measuring the velocity of these waves. Lamb waves can propagate over long distances and are sensitive to the desired in-plane elastic properties of the material. This paper discusses a study in which Lamb waves were used to examine fiber volume fraction variations of approximately 0.40-0.70 in composites. The Lamb wave measurements were compared to fiber volume fractions obtained from acid digestion tests. Additionally, a model to predict the fiber volume fraction from Lamb wave velocity values was evaluated.
Perfusion systems that minimize vascular volume fraction in engineered tissues.
Truslow, James G; Tien, Joe
2011-06-01
This study determines the optimal vascular designs for perfusing engineered tissues. Here, "optimal" describes a geometry that minimizes vascular volume fraction (the fractional volume of a tissue that is occupied by vessels) while maintaining oxygen concentration above a set threshold throughout the tissue. Computational modeling showed that optimal geometries depended on parameters that affected vascular fluid transport and oxygen consumption. Approximate analytical expressions predicted optima that agreed well with the results of modeling. Our results suggest one basis for comparing the effectiveness of designs for microvascular tissue engineering.
FRACTIONAL INTEGRALS WITH VARIABLE KERNELS ON HARDY SPACES
Institute of Scientific and Technical Information of China (English)
ZhangPu; DingYong
2003-01-01
The fractional integral operators with variable kernels are discussed.It is proved that if the kernel satisfies the Dini-condition,then the fractional integral operators with variable kernels are bounded from Hp(Rn) into Lq(Rn) when 0
Laser-induced incandescence: Towards quantitative soot volume fraction measurements
Energy Technology Data Exchange (ETDEWEB)
Tzannis, A.P.; Wienbeucker, F.; Beaud, P.; Frey, H.-M.; Gerber, T.; Mischler, B.; Radi, P.P. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)
1999-08-01
Laser-Induced Incandescence has recently emerged as a versatile tool for measuring soot volume fraction in a wide range of combustion systems. In this work we investigate the essential features of the method. LII is based on the acquisition of the incandescence of soot when heated through a high power laser pulse. Initial experiments have been performed on a model laboratory flame. The behaviour of the LII signal is studied experimentally. By applying numerical calculations we investigate the possibility to obtain two-dimensional soot volume fraction distributions. For this purpose a combination of LII with other techniques is required. This part is discussed in some extent and the future work is outlined. (author) 4 figs., 3 refs.
Gamma ray densitometry techniques for measuring of volume fractions
Energy Technology Data Exchange (ETDEWEB)
Affonso, Renato Raoni Werneck; Silva, Ademir Xavier da; Salgado, Cesar Marques, E-mail: raoniwa@yahoo.com.br, E-mail: ademir@nuclear.ufrj.br, E-mail: otero@ien.gov.br [Instituto de Engenharia Nuclear (IEN/CNEN-RJ), Rio de Janeiro, RJ (Brazil)
2015-07-01
Knowledge of the volume fraction in a multiphase flow is of key importance in predicting the performance of many systems and processes. It is therefore an important parameter to characterize such flows. In the context of nuclear techniques, the gamma ray densitometry is promising and this is due to its non-invasive characteristics and very reliable results. It is used in several applications for multiphase flows (water-oil-air), which are employed tools such as: computational fluid dynamics, artificial neural networks and statistical methods of radiation transport, such as the Monte Carlo method. Based on the gamma radiation techniques for measurements of volume fractions, the aim of this paper is to present several techniques developed for this purpose. (author)
Estimation of liquid volume fraction using ultrasound transit time spectroscopy
Al-Qahtani, Saeed M.; Langton, Christian M.
2016-12-01
It has recently been proposed that the propagation of an ultrasound wave through complex structures, consisting of two-materials of differing ultrasound velocity, may be considered as an array of parallel ‘sonic rays’, the transit time of each determined by their relative proportion; being a minimum (t min) in entire higher velocity material, and a maximum (t max) in entire lower velocity material. An ultrasound transit time spectrum (UTTS) describes the proportion of sonic rays at an individual transit time. It has previously been demonstrated that the solid volume fraction of a solid:liquid composite, specifically acrylic step-wedges immersed in water, may be reliably estimated from the UTTS. The aim of this research was to investigate the hypothesis that the volume fraction of a two-component liquid mixture, of unequal ultrasound velocity, may also be estimated by UTTS. A through-transmission technique incorporating two 1 MHz ultrasound transducers within a horizontally-aligned cylindrical tube-housing was utilised, the proportion of silicone oil to water being varied from 0% to 100%. The liquid volume fraction was estimated from the UTTS at each composition, the coefficient of determination (R 2%) being 98.9 ± 0.7%. The analysis incorporated a novel signal amplitude normalisation technique to compensate for absorption within the silicone oil. It is therefore envisaged that the parallel sonic ray concept and the derived UTTS may be further applied to the quantification of liquid mixture composition assessment.
Volume Fraction of Graphene Platelets in Copper-Graphene Composites
Jagannadham, K.
2013-01-01
Copper-graphene composite films were deposited on copper foil using electrochemical deposition. Four electrolyte solutions that each consist of 250 mL of graphene oxide suspension in distilled water and increasing volume of 0.2 M solution of CuSO4 in steps of 250 mL were used to deposit the composite films with and without a magnetic stirrer. Graphene oxide in the films was reduced to graphene by hydrogen treatment for 6 hours at 673 K (400 °C). The samples were characterized by X-ray diffraction for identification of phases, scanning electron microscopy for distribution of graphene, energy dispersive spectrometry for evaluation of elemental composition, electrical resistivity and temperature coefficient of electrical resistance and thermal conductivity. Effective mean field analysis (EMA) was used to determine the volume fraction and electrical conductivity of graphene and interfacial thermal conductance between graphene and copper. The electrical resistivity was reduced from 2.031 to 1.966 μΩ cm and the thermal conductivity was improved from 3.8 to 5.0 W/cm K upon addition of graphene platelets to electrolytic copper. The use of stirrer during deposition of the films increased the average size and the thickness of the graphene platelets and as a result the improvement in electrical conductivity was lower compared to the values obtained without the stirrer. Using the EMA, the volume fraction of graphene platelets that was responsible for the improvement in the electrical conductivity was found to be lower than that for the improvement in the thermal conductivity. The results of the analysis are used to determine the volume fraction of the thinner and the thicker graphene platelets in the composite films.
Effect of volume fraction on granular avalanche dynamics.
Gravish, Nick; Goldman, Daniel I
2014-09-01
We study the evolution and failure of a granular slope as a function of prepared volume fraction, ϕ(0). We rotated an initially horizontal layer of granular material (0.3-mm-diam glass spheres) to a 45° angle while we monitor the motion of grains from the side and top with high-speed video cameras. The dynamics of grain motion during the tilt process depended sensitively on ϕ(0)∈[0.58-0.63] and differed above or below the granular critical state, ϕ(c), defined as the onset of dilation as a function of increasing volume fraction. For ϕ(0)-ϕ(c)avalanche. Precursor compaction events began at an initial angle θ(0)=7.7±1.4° and occurred intermittently prior to the onset of an avalanche. Avalanches occurred at the maximal slope angle θ(m)=28.5±1.0°. Granular material at ϕ(0)-ϕ(c)>0 did not experience precursor compaction prior to avalanche flow, and instead experienced a single dilational motion at θ(0)=32.1±1.5° prior to the onset of an avalanche at θ(m)=35.9±0.7°. Both θ(0) and θ(m) increased with ϕ(0) and approached the same value in the limit of random close packing. The angle at which avalanching grains came to rest, θ(R)=22±2°, was independent of ϕ(0). From side-view high-speed video, we measured the velocity field of intermittent and avalanching flow. We found that flow direction, depth, and duration were affected by ϕ(0), with ϕ(0)-ϕ(c)0. Our study elucidates how initial conditions-including volume fraction-are important determinants of granular slope stability and the onset of avalanches.
Modified algorithm for generating high volume fraction sphere packings
Valera, Roberto Roselló; Morales, Irvin Pérez; Vanmaercke, Simon; Morfa, Carlos Recarey; Cortés, Lucía Argüelles; Casañas, Harold Díaz-Guzmán
2015-06-01
Advancing front packing algorithms have proven to be very efficient in 2D for obtaining high density sets of particles, especially disks. However, the extension of these algorithms to 3D is not a trivial task. In the present paper, an advancing front algorithm for obtaining highly dense sphere packings is presented. It is simpler than other advancing front packing methods in 3D and can also be used with other types of particles. Comparison with respect to other packing methods have been carried out and a significant improvement in the volume fraction (VF) has been observed. Moreover, the quality of packings was evaluated with indicators other than VF. As additional advantage, the number of generated particles with the algorithm is linear with respect to time.
Determination of Acetonitrile Volume Fraction in Mobile Phase by HPLC
Institute of Scientific and Technical Information of China (English)
WU Yi; WANG Zhi-wu; GU Jing-kai; WANG Ying-wu
2008-01-01
This paper reports the development and validation of an assay for the determination of acetonitrile in the recycled mobile phase using high performance liquid chromatography(HPLC).The method is based on that the retention in reversed-phase liquid chromatography increases with decreasing concentration of organic phase in the mobile phase.The natural logarithm of the capacity ratio for a given solute is linearly related to the volume fraction of the organic modifier in the mobile phase.For dimethylphthalate and diethylphthalate,the linearity range is 30%--60%,and for biphenyl and terphenyl,the range is 60%-95%.Precision values(RSD) were both <1% and the accuracy(RE) was in the range of ±1%.The assay was successfully applied to the determination of acetonitrile concentration of recycled mobile phase after the distillation of the column eluent in our laboratory.
Coarsening in high volume fraction nickel-base alloys
Mackay, R. A.; Nathal, M. V.
1990-01-01
The coarsening behavior of the gamma-prime precipitate has been examined in high volume fraction nickel-base alloys aged at elevated temperatures for times of up to 5000 h. Although the cube rate law was observed during coarsening, none of the presently available coarsening theories showed complete agreement with the experimental particle size distributions (PSDs). These discrepancies were thought to be due to elastic coherency strains which were not considered by the available models. Increasing the Mo content significantly influenced the PSDs and decreased the coarsening rate of the gamma-prime cubes, as a result of increasing the magnitude of the lattice mismatch. After extended aging times, the gamma-prime cubes underwent massive coalescence into plates at a rate which was much faster than the cuboidal coarsening rate. Once the gamma-prime plates were formed, further coarsening was not observed, and this stabilization of the microstructure was attributed to the development of dislocation networks at the gamma-gamma-prime interfaces.
The Effects of Fibre Volume Fraction on a Glass-Epoxy Composite Material
Directory of Open Access Journals (Sweden)
Ciprian LARCO
2015-09-01
Full Text Available This paper focuses on the analysis of the longitudinal mechanical properties of Glass Fibre Reinforce Plastic (GFRP plates with different fibre volume fraction, Vf, by considering both analytical and experimental methods. The laminate is 0/90 E-glass/epoxy woven composite material made by hand lay-up technique. Fiber volume fraction, determined by ignition loss method, has a direct influence on the ultimate strength and modulus of elasticity of the composite plate. Tensile tests on specimens with different volume fractions allow the identification of the mathematical relationship between the fibre volume fraction and the longitudinal elastic modulus.
Conklin, Lindsey
2017-01-01
Fiber-reinforced composite structures have become more common in aerospace components due to their light weight and structural efficiency. In general, the strength and stiffness of a composite structure are directly related to the fiber volume fraction, which is defined as the fraction of fiber volume to total volume of the composite. The most common method to measure the fiber volume fraction is acid digestion, which is a useful method when the total weight of the composite, the fiber weight, and the total weight can easily be obtained. However, acid digestion is a destructive test, so the material will no longer be available for additional characterization. Acid digestion can also be difficult to machine out specific components of a composite structure with complex geometries. These disadvantages of acid digestion led the author to develop a method to calculate the fiber volume fraction. The developed method uses optical microscopy to calculate the fiber area fraction based on images of the cross section of the composite. The fiber area fraction and fiber volume fraction are understood to be the same, based on the assumption that the shape and size of the fibers are consistent in the depth of the composite. This tutorial explains the developed method for optically determining fiber area fraction performed at NASA Langley Research Center.
Accuracy of cancellous bone volume fraction measured by micro-CT scanning
DEFF Research Database (Denmark)
Ding, Ming; Odgaard, A; Hvid, I
1999-01-01
Volume fraction, the single most important parameter in describing trabecular microstructure, can easily be calculated from three-dimensional reconstructions of micro-CT images. This study sought to quantify the accuracy of this measurement. One hundred and sixty human cancellous bone specimens...... which covered a large range of volume fraction (9.8-39.8%) were produced. The specimens were micro-CT scanned, and the volume fraction based on Archimedes' principle was determined as a reference. After scanning, all micro-CT data were segmented using individual thresholds determined by the scanner...
Wear, Keith A
2009-02-01
Frequency-dependent phase velocity was measured in eight cancellous-bone-mimicking phantoms consisting of suspensions of randomly oriented nylon filaments (simulating trabeculae) in a soft-tissue-mimicking medium (simulating marrow). Trabecular thicknesses ranged from 152 to 356 mum. Volume fractions of nylon filament material ranged from 0% to 10%. Phase velocity varied approximately linearly with frequency over the range from 300 to 700 kHz. The increase in phase velocity (compared with phase velocity in a phantom containing no filaments) at 500 kHz was approximately proportional to volume fraction occupied by nylon filaments. The derivative of phase velocity with respect to frequency was negative and exhibited nonlinear, monotonically decreasing dependence on volume fraction. The dependencies of phase velocity and its derivative on volume fraction in these phantoms were similar to those reported in previous studies on (1) human cancellous bone and (2) phantoms consisting of parallel nylon wires immersed in water.
Directory of Open Access Journals (Sweden)
Konrad Wegener
2016-07-01
Full Text Available The influence of fibre volume fraction and temperature on fatigue life of continuous glass fibre reinforced plastics is investigated in detail. The physical causes of the two effects on the slope of the S-N-curve in fibre direction at R = 0.1 are researched and can be explained with help of micrographs. A new phenomenological approach is presented to model both effects in fibre dominated laminates with different stacking sequences using only the static ultimate strength as an input. Static and fatigue tests of different layups and fibre volume fractions are performed at different temperatures to validate the fatigue life predictions. Additionally it is derived that there is an optimal fibre volume fraction regarding a minimum damage sum. This fibre volume fraction is dependent on a given loading spectra and can be calculated using the phenomenological model.
Directory of Open Access Journals (Sweden)
Friedrich Schuler
2015-08-01
Full Text Available The high throughput preparation of emulsions with high internal volume fractions is important for many different applications, e.g., drug delivery. However, most emulsification techniques reach only low internal volume fractions and need stable flow rates that are often difficult to control. Here, we present a centrifugal high throughput step emulsification disk for the fast and easy production of emulsions with high internal volume fractions above 95%. The disk produces droplets at generation rates of up to 3700 droplets/s and, for the first time, enables the generation of emulsions with internal volume fractions of >97%. The coefficient of variation between droplet sizes is very good (4%. We apply our system to show the in situ generation of gel emulsion. In the future, the recently introduced unit operation of centrifugal step emulsification may be used for the high throughput production of droplets as reaction compartments for clinical diagnostics or as starting material for micromaterial synthesis.
Evaluating Volume Fractions of the Elements for Composite Laminates by Using Dielectric Properties
Institute of Scientific and Technical Information of China (English)
周胜; 储才元; 严灏景
2001-01-01
A series and parallel model for investigating the capacity of composite laminates and the relationship between the dielectric properties of the composites and its constituents are presented. Volume fractions of the constituents are considered in this study. The expression of the complex dielectric constants for evaluating volume fractions under discrete frequencies is established and the general solutions for the resultant linear simultaneous equations for system are also exploited.The results show that the high accuracy of proposed method is obtained.
Zhang, Li; Fang, Qiaochu; Gabriel, Florence C; Szücs, Dénes
2014-01-01
Recent studies have indicated that people have a strong tendency to compare fractions based on constituent numerators or denominators. This is called componential processing. This study explored whether componential processing was preferred in tasks involving high stimuli variability and high contextual interference, when fractions could be compared based either on the holistic values of fractions or on their denominators. Here, stimuli variability referred to the fact that fractions were not monotonous but diversiform. Contextual interference referred to the fact that the processing of fractions was interfered by other stimuli. To our ends, three tasks were used. In Task 1, participants compared a standard fraction 1/5 to unit fractions. This task was used as a low stimuli variability and low contextual interference task. In Task 2 stimuli variability was increased by mixing unit and non-unit fractions. In Task 3, high contextual interference was created by incorporating decimals into fractions. The RT results showed that the processing patterns of fractions were very similar for adults and children. In task 1 and task 3, only componential processing was utilzied. In contrast, both holistic processing and componential processing were utilized in task 2. These results suggest that, if individuals are presented with the opportunity to perform componential processing, both adults and children will tend to do so, even if they are faced with high variability of fractions or high contextual interference.
Indian Academy of Sciences (India)
Wenjun Liu; Kewang Chen
2013-09-01
In this paper, we implemented the functional variable method and the modified Riemann–Liouville derivative for the exact solitary wave solutions and periodic wave solutions of the time-fractional Klein–Gordon equation, and the time-fractional Hirota–Satsuma coupled KdV system. This method is extremely simple but effective for handling nonlinear time-fractional differential equations.
Non-monotonic dependence of Pickering emulsion gel rheology on particle volume fraction.
Kaganyuk, M; Mohraz, A
2017-03-29
The microstructure of Pickering emulsion gels features a tenuous network of faceted droplets, bridged together by shared monolayers of particles. In this investigation, we use standard oscillatory rheometry in conjunction with confocal microscopy to gain a more comprehensive understanding of the role particle bridged interfaces have on the rheology of Pickering emulsion gels. The zero-shear elastic modulus of Pickering emulsion gels shows a non-monotonic dependence on particle loading, with three separate regimes of power-law and linear gel strengthening, and subsequent gel weakening. The transition from power-law to linear scaling is found to coincide with a peak in the volume fraction of particles that participate in bridging, which we indirectly calculate using measureable quantities, and the transition to gel weakening is shown to result from a loss in network connectivity at high particle loadings. These observations are explained via a simple representation of how Pickering emulsion gels arise from an initial population of partially-covered droplets. Based on these considerations, we propose a combined variable related to the initial droplet coverage, to be used in reporting and rationalizing the rheology of Pickering emulsion gels. We demonstrate the applicability of this variable with Pickering emulsions prepared at variable fluid ratios and with different-sized colloidal particles. The results of our investigation have important implications for many technological applications that utilize solid stabilized multi-phase emulsions and require a priori knowledge or engineering of their flow characteristics.
Hurdelbrink, Keith R.; Anderson, Jacob P.; Siddique, Zahed; Altan, M. Cengiz
2016-03-01
Bismaleimide (BMI) resin with quartz (AQ581) fiber reinforcement is a composite material frequently used in aerospace applications, such as engine cowlings and radomes. Various composite components used in aircrafts are exposed to different types of hydraulic fluids, which may lead to anomalous absorption behavior over the service life of the composite. Accurate predictive models for absorption of liquid penetrants are particularly important as the composite components are often exposed to long-term degradation due to absorbed moisture, hydraulic fluids, or similar liquid penetrants. Microstructural features such as fiber volume fraction and void fraction can have a significant effect on the absorption behavior of fiber-reinforced composites. In this paper, hydraulic fluid absorption characteristics of quartz/BMI laminates fabricated from prepregs preconditioned at different relative humidity and subsequently cured at different pressures are presented. The composite samples are immersed into hydraulic fluid at room temperature, and were not subjected to any prior degradation. To generate process-induced microvoids, prepregs were conditioned in an environmental chamber at 2% or 99% relative humidity at room temperature for a period of 24 hours prior to laminate fabrication. To alter the fiber volume fraction, the laminates were fabricated at cure pressures of 68.9 kPa (10 psi) or 482.6 kPa (70 psi) via a hot-press. The laminates are shown to have different levels of microvoids and fiber volume fractions, which were observed to affect the absorption dynamics considerably and exhibited clear non-Fickian behavior. A one-dimensional hindered diffusion model (HDM) was shown to be successful in predicting the hydraulic fluid absorption. Model prediction indicates that as the fabrication pressure increased from 68.9 kPa to 482.6 kPa, the maximum fluid content (M∞) decreased from 8.0% wt. to 1.0% wt. The degree of non-Fickian behavior, measured by hindrance coefficient (
Energy Technology Data Exchange (ETDEWEB)
CW Stewart; G Chen; JM Alzheimer; PA Meyer
1998-11-10
The void fraction instrument (WI) was deployed in Tank 241-SY-101 three times in 1998 to confm and locate the retained gas (void) postulated to be causing the accelerating waste level rise observed since 1995. The design, operation, and data reduction model of the WI are described along with validation testing and potential sources of uncertainty. The test plans, field observations and void measurements are described in detail, including the total gas volume calculations and the gas volume model. Based on 1998 data, the void fraction averaged 0.013 i 0.001 in the mixed slurry and 0.30 ~ 0.04 in the crust. This gives gas volumes (at standard pressure and temperature) of 87 t 9 scm in the slurry and 138 ~ 22 scm in the crust for a total retained gas volume of221 *25 scm. This represents an increase of about 74 scm in the crust and a decrease of about 34 scm in the slurry from 1994/95 results. The overall conclusion is that the gas retention is occurring mainly in the crust layer and there is very little gas in the mixed slurry and loosely settled layers below. New insights on crust behavior are also revealed.
Directory of Open Access Journals (Sweden)
K. Narayanan
2014-01-01
Full Text Available The present study was initiated to understand the effect of PLGA concentration, PVA concentration, internal-external phase ratio, homogenization speed, and homogenization time on mean particle size, zeta potential, and percentage drug encapsulation using fractional factorial design. Using PLGA (50-50 as the carrier, hyaluronidase loaded PLGA nanoparticles were prepared using double emulsion solvent evaporation technique. The particle size was analyzed by dynamic light scattering technique and protein content by Lowry method. The study showed that homogenization speed as an independent variable had maximum effect on particle size and zeta potential. Internal-external phase volume ratio had maximum effect on drug encapsulation. Mean particle size also had high dependency on the combined effect of PVA concentration and phase volume ratio. Using fractional factorial design particle size of <400 nm, zeta potential of <−30 mV, and percentage encapsulation of 15–18% were achieved.
GEANT4 simulation of water volume fraction measurement in dehydrated crude oil
Institute of Scientific and Technical Information of China (English)
JING Chunguo; XING Guangzhong; LIU Bin
2007-01-01
Online measurement of water volume fraction (WVF) in dehydrated crude oil is a difficult task due to very little water in dehydrated crude oil and high precision requirements. We presents a method to measure water volume fraction in dehydrated crude oil with γ-ray densitometry. The Monte Carlo computer simulation packet GEANT4 was used to analyze the WVF measuring sensitivity of the γ-ray densitometry at different γ-ray energies, and effects of temperature, pressure, salinity and oil components on WVF measurement. The results show that the γ-ray densitome-try has high sensitivity in γ-ray energy ranges of 16～25 keV, and it can distinguish WVF changes of 0.0005. The calculated WVF decreases about 0.0002 with 1 ℃ of temperature increase and they have approximately linear relation with temperature when water volume fraction remains the same. Effects of pressure, salinity and oil components on water volume fraction can be neglected. Experiments were done to analyze sensitivity of the γ-ray densitometry. The results, as compared with simulations, demonstrate that simulation method is reliable and it is feasible to gauge low water volume fraction using low energy γ-rays.
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Sumedh Dhabu
2015-09-01
Full Text Available This paper presents the design and FPGA implementation of interpolated continuously variable fractional delay structure based filter (ICVFD filter with fine control over the cutoff frequency. In the ICVFD filter, each unit delay of the prototype lowpass filter is replaced by a continuously variable fractional delay (CVFD element proposed in this paper. The CVFD element requires the same number of multiplications as that of the second-order fractional delay structure used in the existing fractional delay structure based variable filter (FDS based filter, however it provides fractional delays corresponding to the higher-order fractional delay structures. Hence, the proposed ICVFD filter provides wider cutoff frequency range compared to the FDS based filter. The ICVFD filter is also capable of providing variable bandpass and highpass responses. We use two-stage approach for the FPGA implementation of the ICVFD filter. First, we use pipelining stages to shorten the critical path and improve the operating frequency. Then, we make use of specific hardware resource, i.e. RAM-based Shift Register (SRL to further improve the operating frequency and resource usage.
An Expansion Formula with Higher-Order Derivatives for Fractional Operators of Variable Order
Directory of Open Access Journals (Sweden)
Ricardo Almeida
2013-01-01
Full Text Available We obtain approximation formulas for fractional integrals and derivatives of Riemann-Liouville and Marchaud types with a variable fractional order. The approximations involve integer-order derivatives only. An estimation for the error is given. The efficiency of the approximation method is illustrated with examples. As applications, we show how the obtained results are useful to solve differential equations, and problems of the calculus of variations that depend on fractional derivatives of Marchaud type.
Mack, Lauren M; Kim, Sung Yoon; Lee, Sungmin; Sangi-Haghpeykar, Haleh; Lee, Wesley
2016-07-01
The purpose of this study was to document the reproducibility and efficiency of a semiautomated image analysis tool that rapidly provides fetal fractional limb volume measurements. Fifty pregnant women underwent 3-dimensional sonographic examinations for fractional arm and thigh volumes at a mean menstrual age of 31.3 weeks. Manual and semiautomated fractional limb volume measurements were calculated, with the semiautomated measurements calculated by novel software (5D Limb Vol; Samsung Medison, Seoul, Korea). The software applies an image transformation method based on the major axis length, minor axis length, and limb center coordinates. A transformed image is used to perform a global optimization technique for determination of an optimal limb soft tissue boundary. Bland-Altman analysis defined bias with 95% limits of agreement (LOA) between methods, and timing differences between manual versus automated methods were compared by a paired t test. Bland-Altman analysis indicated an acceptable bias with 95% LOA between the manual and semiautomated methods: mean arm volume ± SD, 1.7% ± 4.6% (95% LOA, -7.3% to 10.7%); and mean thigh volume, 0.0% ± 3.8% (95% LOA, -7.5% to 7.5%). The computer-assisted software completed measurements about 5 times faster compared to manual tracings. In conclusion, semiautomated fractional limb volume measurements are significantly faster to calculate when compared to a manual procedure. These results are reproducible and are likely to reduce operator dependency. The addition of computer-assisted fractional limb volume to standard biometry may improve the precision of estimated fetal weight by adding a soft tissue component to the weight estimation process.
Effects of volume fraction condition on thermodynamic restrictions in mixture theory
Institute of Scientific and Technical Information of China (English)
牛永红; 苗天德
2002-01-01
Volume fraction condition is a true constraint that must be taken into consideration in deducing the thermodynamic restrictions of mixture theory applying the axiom of dissipation. For a process to be admissible, the constraints imposed by the volume fraction condition include not only the equation obtained by taking its material derivative with respect to the motion of a given phase, but also those by taking its spatial gradient. The thermodynamic restrictions are deduced under the complete constraints, the results obtained are consistent for the mixtures with or without a compressible phase,and in which the free energy of each phase depends on the densities of all phases.
Institute of Scientific and Technical Information of China (English)
MA Yue; LI Wei; LIANG Zi-qing
2008-01-01
Microstmctures of laminates produced by epoxy/ carbon fibers with different fiber volume fraction were studied by analyzing the composite cross-sections. The main result of the compaction of reinforcement is the flatting of bundle shape, the reducing of gap and the embedment of bundles among each layer. The void content outside the bundle decreased sharply during the compoction until it is less than that inside the bundle when the fiber volume fraction is over 60%. The resin flow velocity in the fiber tow is 102-104 times greater than the flow velocity out the fiber tow no matter the capillary pressure is taken into account or not.
Vibrations of FGM thin cylindrical shells with exponential volume fraction law
Institute of Scientific and Technical Information of China (English)
Abdul Ghafar Shah; Tahir Mahmood; Muhammad Nawaz Naeem
2009-01-01
In this paper,the influence of an exponential volume fraction law on the vibration frequencies of thin functionally graded cylindrical shells is studied. Material properties in the shell thickness direction are graded in accordance with the exponential law. Expressions for the strain-displacement and curvature-displacement relationships are taken from Love's thin shell theory. The Rayleigh-Ritz approach is used to derive the shell eigenfrequency equation. Axial modal dependence is assumed in the characteristic beam functions. Natural frequencies of the shells are observed to be dependent on the constituent volume fractions. The results are compared with those available in the literature for the validity of the present methodology.
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Marques Salgado, Cesar [Instituto de Engenharia Nuclear, DIRA/IEN/CNEN, Rio de Janeiro, CEP.: 21945-970-Caixa Postal 68550 (Brazil)], E-mail: otero@ien.gov.br; Brandao, Luis E.B. [Instituto de Engenharia Nuclear, DIRA/IEN/CNEN, Rio de Janeiro, CEP.: 21945-970-Caixa Postal 68550 (Brazil); Schirru, Roberto [Universidade Federal do Rio de Janeiro, PEN/COPPE-DNC/EE-CT, Rio de Janeiro, CEP.: 21941-972-Caixa Postal 68509 (Brazil); Pereira, Claudio M.N.A. [Instituto de Engenharia Nuclear, DIRA/IEN/CNEN, Rio de Janeiro, CEP.: 21945-970-Caixa Postal 68550 (Brazil); Silva, Ademir Xavier da [Universidade Federal do Rio de Janeiro, PEN/COPPE-DNC/EE-CT, Rio de Janeiro, CEP.: 21941-972-Caixa Postal 68509 (Brazil); Ramos, Robson [Instituto de Engenharia Nuclear, DIRA/IEN/CNEN, Rio de Janeiro, CEP.: 21945-970-Caixa Postal 68550 (Brazil)
2009-10-15
This work presents methodology based on nuclear technique and artificial neural network for volume fraction predictions in annular, stratified and homogeneous oil-water-gas regimes. Using principles of gamma-ray absorption and scattering together with an appropriate geometry, comprised of three detectors and a dual-energy gamma-ray source, it was possible to obtain data, which could be adequately correlated to the volume fractions of each phase by means of neural network. The MCNP-X code was used in order to provide the training data for the network.
Numerical Simulations for the Space-Time Variable Order Nonlinear Fractional Wave Equation
Directory of Open Access Journals (Sweden)
Nasser Hassan Sweilam
2013-01-01
Full Text Available The explicit finite-difference method for solving variable order fractional space-time wave equation with a nonlinear source term is considered. The concept of variable order fractional derivative is considered in the sense of Caputo. The stability analysis and the truncation error of the method are discussed. To demonstrate the effectiveness of the method, some numerical test examples are presented.
Random variables as pathwise integrals with respect to fractional Brownian motion
Mishura, Yuliya; Valkeila, Esko
2011-01-01
We show that a pathwise stochastic integral with respect to fractional Brownian motion with an adapted integrand $g$ can have any prescribed distribution, moreover, we give both necessary and sufficient conditions when random variables can be represented in this form. We also prove that any random variable is a value of such integral in some improper sense. We discuss some applications of these results, in particular, to fractional Black--Scholes model of financial market.
Viscosity of water-in-oil emulsions. Variation with temperature and water volume fraction
Energy Technology Data Exchange (ETDEWEB)
Farah, Marco A.; Caldas, Jorge Navaes [Petroleo Brasileiro S.A., Rua General Canabarro, 500, Maracana, Rio, CEP 2057-900 (Brazil); Oliveira, Roberto C. [Petroleo Brasileiro S.A., Cenpes, Cidade Universitaria (Brazil); Rajagopal, Krishnaswamy [LATCA-Laboratorio de Termodinamica e Cinetica Aplicada-Escola de Quimica, Departamento de Engenharia Quimica, Universidade Federal do Rio de Janeiro, UFRJ, Cidade Universitaria, C.P. 68452, CEP 21949-900, Rio de Janeiro (Brazil)
2005-09-15
Water-in-oil emulsions are important in the petroleum industry in production operations, where the water content of the emulsion can be as high as 60% in volume, also in petroleum refining operations where generally the water content is low. The effective viscosity of water-in-oil emulsions depends mainly on the volume fraction of dispersed phase and temperature, along with several minor effects, such as shear rate, average droplet size, droplet size distribution, viscosity and density of oil. Using six different crude oils, the effective viscosities of several synthetic water-in-oil emulsions are measured at atmospheric pressure using a dynamic viscosimeter for different shear rates, temperatures and volume fractions of the dispersed phase. The ASTM equation, method D-341, for describing viscosity as a function of temperature is extended to include the variation of dispersed phase volume fraction. The proposed equation gives good correlation between the measured viscosities of water-in-oil emulsions as a function of temperature and the volume fraction of water.
Imaging air volume fraction in sea ice using non-destructive X-ray tomography
Directory of Open Access Journals (Sweden)
O. Crabeck
2015-09-01
Full Text Available Although the presence of a gas phase in sea ice creates the potential for gas exchange with the atmosphere, the distribution of gas bubbles and transport of gases within the sea ice are still poorly understood. Currently no straightforward technique exists to measure the vertical distribution of air volume fraction in sea ice. Here, we present a new fast and non-destructive X-ray computed tomography technique to quantify the air volume fraction and produce separate 3-D images of air-volume inclusions in sea ice. The technique was performed on relatively thin (4–22 cm sea ice collected from an experimental ice tank. While most of the internal layers showed air-volume fractions 5 mm. While micro bubbles were the most abundant type of air inclusions, most of the air porosity observed resulted from the presence of large and macro bubbles. The ice microstructure (granular and columnar as well as the permeability state of ice are important factors controlling the air volume fraction. The technique developed is suited for studies related to gas transport and bubble migration and can help considerably improving parameterization of these processes in sea ice biogeochemical models.
Imaging air volume fraction in sea ice using non-destructive X-ray tomography
Crabeck, Odile; Galley, Ryan; Delille, Bruno; Else, Brent; Geilfus, Nicolas-Xavier; Lemes, Marcos; Des Roches, Mathieu; Francus, Pierre; Tison, Jean-Louis; Rysgaard, Søren
2016-05-01
Although the presence of a gas phase in sea ice creates the potential for gas exchange with the atmosphere, the distribution of gas bubbles and transport of gases within the sea ice are still poorly understood. Currently no straightforward technique exists to measure the vertical distribution of air volume fraction in sea ice. Here, we present a new fast and non-destructive X-ray computed tomography technique to quantify the air volume fraction and produce separate images of air volume inclusions in sea ice. The technique was performed on relatively thin (4-22 cm) sea ice collected from an experimental ice tank. While most of the internal layers showed air volume fractions bubbles (Ø bubbles (1 mm bubbles (Ø > 5 mm). While micro bubbles were the most abundant type of gas bubbles, most of the air porosity observed resulted from the presence of large and macro bubbles. The ice texture (granular and columnar) as well as the permeability state of ice are important factors controlling the air volume fraction. The technique developed is suited for studies related to gas transport and bubble migration.
Surface area and volume fraction of random open-pore systems
Hermann, H.; Elsner, A.; Stoyan, D.
2013-12-01
For the first time, explicit approximate formulas are presented for the volume fraction and specific surface area of random open-pore systems with poly-disperse pore size distributions. It is shown that the formulas are valid for broad classes of models for porous media characterized by tunable pore size distributions and a variable degree of inter-penetrability of pores. The formulas for the poly-disperse case are based on expressions derived previously for mono-disperse penetrable-sphere models. The results are obtained by analysis of a series of open-pore models, which are prepared by computer simulation of systems of randomly packed partially penetrable spheres with various poly-disperse size distributions such as gamma, lognormal, and Gaussian. The formulas are applied in a study of atomic layer deposition processes on open-pore systems, and the effective Young's modulus and the effective thermal conductivity of Al2O3 coated porous polypropylene electrodes for lithium ion batteries are predicted.
Hesameddini, Esmail; Rahimi, Azam
2015-05-01
In this article, we propose a new approach for solving fractional partial differential equations with variable coefficients, which is very effective and can also be applied to other types of differential equations. The main advantage of the method lies in its flexibility for obtaining the approximate solutions of time fractional and space fractional equations. The fractional derivatives are described based on the Caputo sense. Our method contains an iterative formula that can provide rapidly convergent successive approximations of the exact solution if such a closed form solution exists. Several examples are given, and the numerical results are shown to demonstrate the efficiency of the newly proposed method.
Energy Technology Data Exchange (ETDEWEB)
Bautista, Zhierwinjay M.; Shin, Hyung Seop [Dept. of Mechanical Design Engineering, Andong National University, Andong (Korea, Republic of); Lee, Jae Hun; Lee, Hun Ju; Moon, Seung Hyun [SuNAM Co Ltd., Anseong (Korea, Republic of)
2016-09-15
The enhancement of mechanical properties of coated conductor (CC) tapes in practical application are usually achieved by reinforcing through lamination or electroplating metal layers on either sides of the CC tape. Mechanical or electromechanical properties of the CC tapes have been largely affected by the lamination structure under various loading modes such as tension, bending or even cyclic. In this study, the influence of brass laminate volume fraction on electromechanical properties of RCE-DR processed Gadolinium-barium-copper-oxide (GdBCO) CC tapes was investigated. The samples used were composed of single-side and both-side laminate of brass layer to the Cu-stabilized CC tape and their Ic behaviors were compared to those of the Cu-stabilized CC tape without external lamination. The stress/strain dependences of Ic in laminated CC tapes under uniaxial tension were analyzed and the irreversible stress/strain limits were determined. As a result, the increase of brass laminate volume fraction initially increased the irreversible strain limit and became gradual. The corresponding irreversible stress limit, however, showed no difference even though the brass laminate volume fraction increased to 3.4. But the irreversible load limit linearly increased with the brass laminate volume fraction.
Spinal cord tolerance to single-fraction partial-volume irradiation: a swine model
Medin, P.M.; Foster, R.D.; Kogel, A.J. van der; Sayre, J.W.; McBride, W.H.; Solberg, T.D.
2011-01-01
PURPOSE: To determine the spinal cord tolerance to single-fraction, partial-volume irradiation in swine. METHODS AND MATERIALS: A 5-cm-long cervical segment was irradiated in 38-47-week-old Yucatan minipigs using a dedicated, image-guided radiosurgery linear accelerator. The radiation was delivered
Directory of Open Access Journals (Sweden)
Bogdan Gheorghe Munteanu
2013-01-01
Full Text Available Using the stochastic approximations, in this paper it was studiedthe convergence in distribution of the fractional parts of the sum of random variables to the truncated exponential distribution with parameter lambda. This fact is feasible by means of the Fourier-Stieltjes sequence (FSS of the random variable.
Solving Time-Fractional Advection-Dispersion Equation by Variable Weights Particle Tracking Method
Cao, Shaohua; Jiang, Jianguo; Wu, Jichun
2017-09-01
Particle tracking method is an efficient and reliable method to solve time-fractional advection-dispersion equation, which can describe anomalous transport in heterogeneous porous media. However, this method will lead to severe fluctuation or disappearance of solutions if the concentration value is small. A variable weights method is developed to conquer the shortcoming of particle tracking method. Then, one-dimensional and two-dimensional time-fractional advection-dispersion equations are solved by the variable weights particle tracking method. Compared to traditional particle tracking method, the variable weights version may eliminate the fluctuation and improve the accuracy by orders of magnitude without more computational cost.
Determination of volume fractions of texture components with standard distributions in Euler space
Cho, Jae-Hyung; Rollett, A. D.; Oh, K. H.
2004-03-01
The intensities of texture components are modeled by Gaussian distribution functions in Euler space. The multiplicities depend on the relation between the texture component and the crystal and sample symmetry elements. Higher multiplicities are associated with higher maximum values in the orientation distribution function (ODF). The ODF generated by Gaussian function shows that the S component has a multiplicity of 1, the brass and copper components, 2, and the Goss and cube components, 4 in the cubic crystal and orthorhombic sample symmetry. Typical texture components were modeled using standard distributions in Euler space to calculate a discrete ODF, and their volume fractions were collected and verified against the volume used to generate the ODF. The volume fraction of a texture component that has a standard spherical distribution can be collected using the misorientation approach. The misorientation approach means integrating the volume-weighted intensity that is located within a specified cut-off misorientation angle from the ideal orientation. The volume fraction of a sharply peaked texture component can be collected exactly with a small cut-off value, but textures with broad distributions (large full-width at half-maximum (FWHM)) need a larger cut-off value. Larger cut-off values require Euler space to be partitioned between texture components in order to avoid overlapping regions. The misorientation approach can be used for texture's volume in Euler space in a general manner. Fiber texture is also modeled with Gaussian distribution, and it is produced by rotation of a crystal located at g 0, around a sample axis. The volume of fiber texture in wire drawing or extrusion also can be calculated easily in the unit triangle with the angle distance approach.
Determination of volume fractions in two-phase flows from sound speed measurement
Energy Technology Data Exchange (ETDEWEB)
Chaudhuri, Anirban [Los Alamos National Laboratory; Sinha, Dipen N. [Los Alamos National Laboratory; Osterhoudt, Curtis F. [University of Alaska
2012-08-15
Accurate measurement of the composition of oil-water emulsions within the process environment is a challenging problem in the oil industry. Ultrasonic techniques are promising because they are non-invasive and can penetrate optically opaque mixtures. This paper presents a method of determining the volume fractions of two immiscible fluids in a homogenized two-phase flow by measuring the speed of sound through the composite fluid along with the instantaneous temperature. Two separate algorithms are developed by representing the composite density as (i) a linear combination of the two densities, and (ii) a non-linear fractional formulation. Both methods lead to a quadratic equation with temperature dependent coefficients, the root of which yields the volume fraction. The densities and sound speeds are calibrated at various temperatures for each fluid component, and the fitted polynomial is used in the final algorithm. We present results when the new algorithm is applied to mixtures of crude oil and process water from two different oil fields, and a comparison of our results with a Coriolis meter; the difference between mean values is less than 1%. Analytical and numerical studies of sensitivity of the calculated volume fraction to temperature changes and calibration errors are also presented.
Tumor classification using perfusion volume fractions in breast DCE-MRI
Lee, Sang Ho; Kim, Jong Hyo; Park, Jeong Seon; Park, Sang Joon; Jung, Yun Sub; Song, Jung Joo; Moon, Woo Kyung
2008-03-01
This study was designed to classify contrast enhancement curves using both three-time-points (3TP) method and clustering approach at full-time points, and to introduce a novel evaluation method using perfusion volume fractions for differentiation of malignant and benign lesions. DCE-MRI was applied to 24 lesions (12 malignant, 12 benign). After region growing segmentation for each lesion, hole-filling and 3D morphological erosion and dilation were performed for extracting final lesion volume. 3TP method and k-means clustering at full-time points were applied for classifying kinetic curves into six classes. Intratumoral volume fraction for each class was calculated. ROC and linear discriminant analyses were performed with distributions of the volume fractions for each class, pairwise and whole classes, respectively. The best performance in each class showed accuracy (ACC), 84.7% (sensitivity (SE), 100%; specificity (SP), 66.7% to a single class) to 3TP method, whereas ACC, 73.6% (SE, 41.7%; SP, 100% to a single class) to k-means clustering. The best performance in pairwise classes showed ACC, 75% (SE, 83.3%; SP, 66.7% to four class pairs and SE, 58.3%; SP, 91.7% to a single class pair) to 3TP method and ACC, 75% (SE, 75%; SP, 75% to a single class pair and SE, 66.7%; SP, 83.3% to three class pairs) to k-means clustering. The performance in whole classes showed ACC, 75% (SE, 83.3%; SP, 66.7%) to 3TP method and ACC, 75% (SE, 91.7%; 58.3%) to k-means clustering. The results indicate that tumor classification using perfusion volume fractions is helpful in selecting meaningful kinetic patterns for differentiation of malignant and benign lesions, and that two different classification methods are complementary to each other.
Institute of Scientific and Technical Information of China (English)
Zhang Ruo-Xun; Yang Shi-Ping
2012-01-01
In this paper we investigate the synchronization of a class of three-dimensional fractional-order chaotic systems.Based on the Lyapunov stability theory and adaptive control technique,a single adaptive-feedback controller is developed to synchronize a class of fractional-order chaotic systems.The presented controller which only contains a single driving variable is simple both in design and in implementation.Numerical simulation and circuit experimental results for fractional-order chaotic system are provided to illustrate the effectiveness of the proposed scheme.
On the use of fractional calculus for the probabilistic characterization of random variables
Cottone, Giulio; 10.1016/j.probengmech.2008.08.002
2013-01-01
In this paper, the classical problem of the probabilistic characterization of a random variable is re-examined. A random variable is usually described by the probability density function (PDF) or by its Fourier transform, namely the characteristic function (CF). The CF can be further expressed by a Taylor series involving the moments of the random variable. However, in some circumstances, the moments do not exist and the Taylor expansion of the CF is useless. This happens for example in the case of $\\alpha$--stable random variables. Here, the problem of representing the CF or the PDF of random variables (r.vs) is examined by introducing fractional calculus. Two very remarkable results are obtained. Firstly, it is shown that the fractional derivatives of the CF in zero coincide with fractional moments. This is true also in case of CF not derivable in zero (like the CF of $\\alpha$--stable r.vs). Moreover, it is shown that the CF may be represented by a generalized Taylor expansion involving fractional moments. ...
The equivalent electrical permittivity of gas-solid mixtures at intermediate solid volume fractions.
Energy Technology Data Exchange (ETDEWEB)
Torczynski, John Robert; Ceccio, Steven Louis; Tortora, Paul Richard
2005-07-01
Several mixture models are evaluated for their suitability in predicting the equivalent permittivity of dielectric particles in a dielectric medium for intermediate solid volume fractions (0.4 to 0.6). Predictions of the Maxwell, Rayleigh, Bottcher and Bruggeman models are compared to computational simulations of several arrangements of solid particles in a gas and to the experimentally determined permittivity of a static particle bed. The experiment uses spherical glass beads in air, so air and glass permittivity values (1 and 7, respectively) are used with all of the models and simulations. The experimental system used to measure the permittivity of the static particle bed and its calibration are described. The Rayleigh model is found to be suitable for predicting permittivity over the entire range of solid volume fractions (0-0.6).
Volume fraction prediction in biphasic flow using nuclear technique and artificial neural network
Energy Technology Data Exchange (ETDEWEB)
Salgado, Cesar M.; Brandao, Luis E.B., E-mail: otero@ien.gov.br, E-mail: brandao@ien.gov.br [Instituto de Engenharia Nuclear (IEN/CNEN-RJ), Rio de Janeiro, RJ (Brazil)
2015-07-01
The volume fraction is one of the most important parameters used to characterize air-liquid two-phase flows. It is a physical value to determine other parameters, such as the phase's densities and to determine the flow rate of each phase. These parameters are important to predict the flow pattern and to determine a mathematical model for the system. To study, for example, heat transfer and pressure drop. This work presents a methodology for volume fractions prediction in water-gas stratified flow regime using the nuclear technique and artificial intelligence. The volume fractions calculate in biphasic flow systems is complex and the analysis by means of analytical equations becomes very difficult. The approach is based on gamma-ray pulse height distributions pattern recognition by means of the artificial neural network. The detection system uses appropriate broad beam geometry, comprised of a ({sup 137}Cs) energy gamma-ray source and a NaI(Tl) scintillation detector in order measure transmitted beam whose the counts rates are influenced by the phases composition. These distributions are directly used by the network without any parameterization of the measured signal. The ideal and static theoretical models for stratified regime have been developed using MCNP-X code, which was used to provide training, test and validation data for the network. The detector also was modeled with this code and the results were compared to experimental photopeak efficiency measurements of radiation sources. The proposed network could obtain with satisfactory prediction of the volume fraction in water-gas system, demonstrating to be a promising approach for this purpose. (author)
Energy Technology Data Exchange (ETDEWEB)
Brown, Judith Alice [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Long, Kevin Nicholas [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
2017-05-01
This work was done to support customer questions about whether a Sylgard/Glass Microballoon (GMB) potting material in current use could be replaced with pure Sylgard and if this would significantly change stresses imparted to internal components under thermal cycling conditions. To address these questions, we provide micromechanics analysis of Sylgard/GMB materials using both analytic composite theory and finite element simulations to better understand the role of the GMB volume fraction in determining thermal expansion coefficient, elastic constants, and behavior in both confined and unconfined compression boundary value problems. A key finding is that damage accumulation in the material from breakage of GMBs significantly limits the global stress magnitude and results in a plateau stress behavior over large ranges of compressive strain. The magnitude of this plateau stress is reduced with higher volume fractions of GMBs. This effect is particularly pronounced in confined compression, which we estimate bears the most similarity to the application of interest. This stress-limiting damage mechanism is not present in pure Sylgard, however, and the result is much higher stresses under confined compression. Thus, we recommend that some volume fraction greater than 10% GMBs be used for confined deformation applications.
Masuram, N. B.; Roux, J. A.; Jeswani, A. L.
2016-06-01
Liquid resin is injected into the tapered injection chamber through the injection slots to completely wetout the fiber reinforcements in a resin injection pultrusion process. As the resin penetrates through the fibers, the resin also pushes the fibers away from the wall towards the centerline causing compaction of the fiber reinforcements. The fibers are squeezed together due to compaction, making resin penetration more difficult; thus higher resin injection pressures are required to effectively penetrate through the fibers and achieve complete wetout. Fiber volume fraction in the final pultruded composite is a key to decide the mechanical and/or chemical properties of the composite. If the fiber volume fraction is too high, more fibers are squeezed together creating a fiber lean region near the wall and fiber rich region away from the wall. Also, the design of the injection chamber significantly affects the minimum injection pressure required to completely wet the fibers. A tapered injection chamber is considered such that wetout occurs at lower injection pressures due to the taper angle of the injection chamber. In this study, the effect of fiber volume fraction on the fiber reinforcement compaction and complete fiber wetout for a tapered injection chamber is investigated.
Energy Technology Data Exchange (ETDEWEB)
Salgado, C.M.; Pereira, Claudio M.N.A.; Brandao, Luis E.B., E-mail: otero@ien.gov.b, E-mail: cmnap@ien.gov.b, E-mail: brandao@ien.gov.b [Instituto de Engenharia Nuclear (DIRA/IEN/CNEN-RJ), Rio de Janeiro, RJ (Brazil). Div. de Radiofarmacos
2011-07-01
This work investigates the response of a volume fraction prediction system for water-gas-oil multiphase flows considering variations on water salinity. The approach is based on gamma-ray pulse height distributions pattern recognition by means the artificial neural networks (ANNs). The detection system uses appropriate fan beam geometry, comprised of a dual-energy gamma-ray source and two NaI(Tl) detectors adequately positioned outside the pipe in order measure transmitted and scattered beams. An ideal and static theoretical model for annular flow regime have been developed using MCNP-X code, which was used to provide training, test and validation data for the ANN. More than 500 simulations have been done, in which water salinity have been ranged from 0 to 16% in order to cover a most practical situations. Validation tests have included values of volume fractions and water salinity different from those used in ANN training phase. The results presented here show that the proposed approach may be successfully applied to material volume fraction prediction on watergas- oil multiphase flows considering practical (real) levels of variations in water salinity. (author)
Simulation of Variable Air Volume System with Different Duct Layout
Institute of Scientific and Technical Information of China (English)
CHEN Hua(陈华); TU Guang-bei(涂光备); FRANCIS W H Yik
2004-01-01
The duct static pressure reset (DSPR) control method is a popular modern control method widely applied to variable air volume (VAV) systems of commercial buildings. In this paper, a VAV system simulation program was used to predict the system performance and zone air temperature of two kinds of layouts that were applied to a typical floor of an existing building office in Hong Kong. The position where the static pressure sensor was placed should affect the zones temperature and energy consumption. The comparison of predictions of the two kinds of layouts indicates that with the same DSPR control method the layout of the air duct might influence the fan control result and energy savings.
Nisari, Mehtap; Ertekin, Tolga; Ozçelik, Ozlem; Cınar, Serife; Doğanay, Selim; Acer, Niyazi
2012-11-01
Brain development in early life is thought to be critical period in neurodevelopmental disorder. Knowledge relating to this period is currently quite limited. This study aimed to evaluate the volume relation of total brain (TB), cerebrum, cerebellum and bulbus+pons by the use of Archimedes' principle and stereological (point-counting) method and after that to compare these approaches with each other in newborns. This study was carried out on five newborn cadavers mean weighing 2.220 ± 1.056 g with no signs of neuropathology. The mean (±SD) age of the subjects was 39.7 (±1.5) weeks. The volume and volume fraction of the total brain, cerebrum, cerebellum and bulbus+pons were determined on magnetic resonance (MR) images using the point-counting approach of stereological methods and by the use of fluid displacement technique. The mean (±SD) TB, cerebrum, cerebellum and bulbus+pons volumes by fluid displacement were 271.48 ± 78.3, 256.6 ± 71.8, 12.16 ± 6.1 and 2.72 ± 1.6 cm3, respectively. By the Cavalieri principle (point-counting) using sagittal MRIs, they were 262.01 ± 74.9, 248.11 ± 68.03, 11.68 ± 6.1 and 2.21 ± 1.13 cm3, respectively. The mean (± SD) volumes by point-counting technique using axial MR images were 288.06 ± 88.5, 275.2 ± 83.1, 19.75 ± 5.3 and 2.11 ± 0.7 cm3, respectively. There were no differences between the fluid displacement and point-counting (using axial and sagittal images) for all structures (p > 0.05). This study presents the basic data for studies relative to newborn's brain volume fractions according to two methods. Stereological (point-counting) estimation may be accepted a beneficial and new tool for neurological evaluation in vivo research of the brain. Based on these techniques we introduce here, the clinician may evaluate the growth of the brain in a more efficient and precise manner.
Takao, H; Hayashi, N; Ohtomo, K
2013-02-12
Diffusion tensor imaging (DTI) provides information regarding white matter microstructure; however, macroscopic fiber architectures can affect DTI measures. A larger brain (fiber tract) has a 'relatively' smaller voxel size, and the voxels are less likely to contain more than one fiber orientation and more likely to have higher fractional anisotropy (FA). Previous DTI studies report left-to-right differences in the white matter; however, these may reflect true microscopic differences or be caused purely by volume differences. Using tract-based spatial statistics, we investigated left-to-right differences in white matter microstructure across the whole brain. Voxel-wise analysis revealed a large number of white matter volume asymmetries, including leftward asymmetry of the arcuate fasciculus and cingulum. In many white matter regions, FA asymmetry was positively correlated with volume asymmetry. Voxel-wise analysis with adjustment for volume asymmetry revealed many white matter FA asymmetries, including leftward asymmetry of the arcuate fasciculus and cingulum. The voxel-wise analysis showed a reduced number of regions with significant FA asymmetry compared with analysis performed without adjustment for volume asymmetry; however, the overall trend of the results was unchanged. The results of the present study suggest that these FA asymmetries are not caused by volume differences and reflect microscopic differences in the white matter.
Peng, Xiaoguang; McKenna, Gregory B.
2016-04-01
Three important kinetic phenomena have been cataloged by Kovacs in the investigation of molecular glasses during structural recovery or physical aging. These are responses to temperature-jump histories referred to as intrinsic isotherms, asymmetry of approach, and memory effect. Here we use a thermosensitive polystyrene-poly (N -isopropylacrylamide)-poly (acrylic acid) core-shell particle-based dispersion as a colloidal model and by working at a constant number concentration of particles we use temperature changes to create volume-fraction changes. This imposes conditions similar to those defined by Kovacs on the colloidal system. We use creep experiments to probe the physical aging and structural recovery behavior of colloidal glasses in the Kovacs-type histories and compare the results with those seen in molecular glasses. We find that there are similarities in aging dynamics between molecular glasses and colloidal glasses, but differences also persist. For the intrinsic isotherms, the times teq needed for relaxing or evolving into the equilibrium (or stationary) state are relatively insensitive to the volume fraction and the values of teq are longer than the α -relaxation time τα at the same volume fraction. On the other hand, both of these times grow at least exponentially with decreasing temperature in molecular glasses. For the asymmetry of approach, similar nonlinear behavior is observed for both colloidal and molecular glasses. However, the equilibration time teq is the same for both volume-fraction up-jump and down-jump experiments, different from the finding in molecular glasses that it takes longer for the structure to evolve into equilibrium for the temperature up-jump condition than for the temperature down-jump condition. For the two-step volume-fraction jumps, a memory response is observed that is different from observations of structural recovery in two-step temperature histories in molecular glasses. The concentration dependence of the dynamics
Hoppmann, Mario; Hunkeler, Priska A.; Hendricks, Stefan; Kalscheuer, Thomas; Gerdes, Rüdiger
2016-04-01
In Antarctica, ice crystals (platelets) form and grow in supercooled waters below ice shelves. These platelets rise, accumulate beneath nearby sea ice, and subsequently form a several meter thick, porous sub-ice platelet layer. This special ice type is a unique habitat, influences sea-ice mass and energy balance, and its volume can be interpreted as an indicator of the health of an ice shelf. Although progress has been made in determining and understanding its spatio-temporal variability based on point measurements, an investigation of this phenomenon on a larger scale remains a challenge due to logistical constraints and a lack of suitable methodology. In the present study, we applied a lateral constrained Marquardt-Levenberg inversion to a unique multi-frequency electromagnetic (EM) induction sounding dataset obtained on the ice-shelf influenced fast-ice regime of Atka Bay, eastern Weddell Sea. We adapted the inversion algorithm to incorporate a sensor specific signal bias, and confirmed the reliability of the algorithm by performing a sensitivity study using synthetic data. We inverted the field data for sea-ice and platelet-layer thickness and electrical conductivity, and calculated ice-volume fractions within the platelet layer using Archie's Law. The thickness results agreed well with drillhole validation datasets within the uncertainty range, and the ice-volume fraction yielded results comparable to other studies. Both parameters together enable an estimation of the total ice volume within the platelet layer, which was found to be comparable to the volume of landfast sea ice in this region, and corresponded to more than a quarter of the annual basal melt volume of the nearby Ekström Ice Shelf. Our findings show that multi-frequency EM induction sounding is a suitable approach to efficiently map sea-ice and platelet-layer properties, with important implications for research into ocean/ice-shelf/sea-ice interactions. However, a successful application of this
Effect of volume fraction of Polypropylene Fiber on Mechanical Properties of Concrete
Directory of Open Access Journals (Sweden)
R. S. Rajguru,
2014-06-01
Full Text Available In this study, the result of polypropylene fiber on mechanical properties of concrete is studied. Polypropylene fibers of 12mm cut length and 6 denier were added at volume fraction of 0%, 0.25%, 0.50%, 0.75% & 1 %.The cube, cylinder and beams wear tested under two point loads on UTM. The results showed that the addition of polypropylene fiber significantly improved the compressive strength, split tensile strength, flexural strength, reserve strength and ductility of fiber reinforced concrete.
Study of the free volume fraction in polylactic acid (PLA) by thermal analysis
Abdallah, A.; Benrekaa, N.
2015-10-01
The poly (lactic acid) or polylactide (PLA) is a biodegradable polymer with high modulus, strength and thermoplastic properties. In this work, the evolution of various properties of PLA is studied, such as glass transition temperature, mechanical modules and elongation percentage with the aim of investigating the free volume fraction. To do so, two thermal techniques have been used: the dynamic mechanical analysis (DMA) and dilatometry. The results obtained by these techniques are combined to go back to the structural properties of the studied material.
LENUS (Irish Health Repository)
Mullaney, L.
2014-01-10
Organ motion is a contributory factor to the variation in location of the prostate and organs at risk during a course of fractionated prostate radiation therapy (RT). A prospective randomized controlled trial was designed with the primary endpoint to provide evidence-based bladder-filling instructions to achieve a consistent bladder volume (BV) and thus reduce the bladder-related organ motion. The secondary endpoints were to assess the incidence of acute and late genitourinary (GU) and gastrointestinal (GI) toxicity for patients and patients’ satisfaction with the bladder-filling instructions.
Variable-Volume Flushing (V-VF) device for water conservation in toilets
Jasper, Louis J., Jr.
1993-01-01
Thirty five percent of residential indoor water used is flushed down the toilet. Five out of six flushes are for liquid waste only, which requires only a fraction of the water needed for solid waste. Designers of current low-flush toilets (3.5-gal. flush) and ultra-low-flush toilets (1.5-gal. flush) did not consider the vastly reduced amount of water needed to flush liquid waste versus solid waste. Consequently, these toilets are less practical than desired and can be improved upon for water conservation. This paper describes a variable-volume flushing (V-VF) device that is more reliable than the currently used flushing devices (it will not leak), is simple, more economical, and more water conserving (allowing one to choose the amount of water to use for flushing solid and liquid waste).
Guermond, J.-L.
2011-01-01
In this paper we analyze the convergence properties of a new fractional time-stepping technique for the solution of the variable density incompressible Navier-Stokes equations. The main feature of this method is that, contrary to other existing algorithms, the pressure is determined by just solving one Poisson equation per time step. First-order error estimates are proved, and stability of a formally second-order variant of the method is established. © 2011 Society for Industrial and Applied Mathematics.
Peritoneal residual volume induces variability of ultrafiltration with icodextrin.
Akonur, Alp; Holmes, Clifford J; Leypoldt, John K
2014-01-01
Icodextrin induces ultrafiltration (UF) during long-dwell exchanges by creating a difference in oncotic pressure between the peritoneal cavity and plasma; however, the mechanisms governing intra-patient and inter-patient variability in UF when icodextrin is used remain largely unexplained. In the present study, we show theoretically that differences in peritoneal residual volume (VR) have a more profound effect on UF with icodextrin use than with glucose use. This phenomenon is attributed to a differential effect of VR on oncotic, rather than osmotic, pressure between the peritoneal cavity and plasma. ♢ The three-pore model was used to calculate the effect on UF of VR between 150 mL and 1200 mL when 7.5% icodextrin (ICO) or 3.86% glucose solution is used at the end of a 12-hour dwell in the four patient transport groups (that is, fast to slow). Oncotic (with ICO) and osmotic (with glucose) pressure differences averaged over the entire dwell were also calculated. ♢ As expected, at a nominal VR of 300 mL, UF with glucose differed substantially between the four patient transport groups (2 - 804 mL), whereas UF with ICO did not (556 - 573 mL). When VR was increased to 1200 mL from 150 mL, the concentrations of the oncotic and osmotic agents at the start of the dwell with an infusion volume of 2 L decreased to 4.9% from 7.0% with ICO and to 2.5% from 3.6% with glucose. The decrease in UF on average was greater with ICO [to 252 mL from 624 mL: that is, a reduction of 372 mL (60%)] than with glucose [to 292 mL from 398 mL: that is, a reduction of 106 mL (27%)]. Those trends agreed with the calculated reductions in the oncotic pressure difference with ICO [reduction of 12 mmHg (49%)] and the osmotic pressure difference with glucose [reduction of 19 mmHg (33%)]. ♢ When ICO is used, VR modifies the oncotic pressure difference between the peritoneal cavity and plasma to substantially alter UF. This modification suggests that potential causes of increased VR should be
Li, Calvin H.; Peterson, G. P.
2006-04-01
An experimental investigation was conducted to examine the effects of variations in the temperature and volume fraction on the steady-state effective thermal conductivity of two different nanoparticle suspensions. Copper and aluminum oxide, CuO and Al2O3, nanoparticles with area weighted diameters of 29 and 36 nm, respectively, were blended with distilled water at 2%, 4%, 6%, and 10% volume fractions and the resulting suspensions were evaluated at temperatures ranging from 27.5 to 34.7 °C. The results indicate that the nanoparticle material, diameter, volume fraction, and bulk temperature, all have a significant impact on the effective thermal conductivity of these suspensions. The 6% volume fraction of CuO nanoparticle/distilled water suspension resulted in an increase in the effective thermal conductivity of 1.52 times that of pure distilled water and the 10% Al2O3 nanoparticle/distilled water suspension increased the effective thermal conductivity by a factor of 1.3, at a temperature of 34 °C. A two-factor linear regression analysis based on the temperature and volume fraction was applied and indicated that the experimental results are in stark contrast to the trends predicted by the traditional theoretical models with respect to both temperature and volume fraction. The available models are reviewed and the possible reasons for the unusually high effective thermal conductivity of nanofluids are analyzed and discussed.
Wille, Marie-Luise; Langton, Christian M
2016-02-01
The acceptance of broadband ultrasound attenuation (BUA) for the assessment of osteoporosis suffers from a limited understanding of both ultrasound wave propagation through cancellous bone and its exact dependence upon the material and structural properties. It has recently been proposed that ultrasound wave propagation in cancellous bone may be described by a concept of parallel sonic rays; the transit time of each ray defined by the proportion of bone and marrow propagated. A Transit Time Spectrum (TTS) describes the proportion of sonic rays having a particular transit time, effectively describing the lateral inhomogeneity of transit times over the surface aperture of the receive ultrasound transducer. The aim of this study was to test the hypothesis that the solid volume fraction (SVF) of simplified bone:marrow replica models may be reliably estimated from the corresponding ultrasound transit time spectrum. Transit time spectra were derived via digital deconvolution of the experimentally measured input and output ultrasonic signals, and compared to predicted TTS based on the parallel sonic ray concept, demonstrating agreement in both position and amplitude of spectral peaks. Solid volume fraction was calculated from the TTS; agreement between true (geometric calculation) with predicted (computer simulation) and experimentally-derived values were R(2)=99.9% and R(2)=97.3% respectively. It is therefore envisaged that ultrasound transit time spectroscopy (UTTS) offers the potential to reliably estimate bone mineral density and hence the established T-score parameter for clinical osteoporosis assessment.
Prediction of Shrinkage Pore Volume Fraction Using a Dimensionless Niyama Criterion
Carlson, Kent D.; Beckermann, Christoph
2009-01-01
A method is presented to use a dimensionless form of the well-known Niyama criterion to directly predict the amount of shrinkage porosity that forms during solidification of metal alloy castings. The main advancement offered by this method is that it avoids the need to know the threshold Niyama value below which shrinkage porosity forms; such threshold values are generally unknown and alloy dependent. The dimensionless criterion accounts for both the local thermal conditions (as in the original Niyama criterion) and the properties and solidification characteristics of the alloy. Once a dimensionless Niyama criterion value is obtained from casting simulation results, the corresponding shrinkage pore volume fraction can be determined knowing only the solid fraction-temperature curve and the total solidification shrinkage of the alloy. Curves providing the shrinkage pore volume percentage as a function of the dimensionless Niyama criterion are given for WCB steel, aluminum alloy A356, and magnesium alloy AZ91D. The present method is used in a general-purpose casting simulation software package to predict shrinkage porosity in three-dimensional (3-D) castings. Comparisons between simulated and experimental shrinkage porosity results for a WCB steel plate casting demonstrate that this method can reasonably predict shrinkage. Additional simulations for magnesium alloy AZ91D illustrate that this method is applicable to a wide variety of alloys and casting conditions.
Prediction of the Soil Water Characteristic from Soil Particle Volume Fractions
DEFF Research Database (Denmark)
Naveed, Muhammad; Møldrup, Per; Tuller, Markus
2012-01-01
Modelling water distribution and flow in partially saturated soils requires knowledge of the soil-water characteristic (SWC). However, measurement of the SWC is challenging and time-consuming, and in some cases not feasible. This study introduces two predictive models (Xw-model and Xw......*-model) for the SWC, derived from readily available soil properties such as texture and bulk density. A total of 46 soils from different horizons at 15 locations across Denmark were used for models evaluation. The Xw-model predicts the volumetric water content as a function of volumetric fines content (organic matter...... (organic matter, clay, silt, fine and coarse sand), variably included in the model depending on the pF value. The volumetric content of a particular soil particle size fraction was included in the model if it was assumed to contribute to the pore size fraction still occupied with water at the given p...
Fractionated Mercury Isotopes in Fish: The Effects of Nuclear Mass, Spin, and Volume
Das, R.; Odom, A. L.
2007-12-01
.3, and thus more than one mass-independent isotope effect is inferred. MIF of mercury can be caused by the nuclear volume effect. Schauble, 2007 has calculated nuclear volume fractionation scaling factors for a number of common mercury chemical species in equilibrium with Hg° vapor. From his calculations the nuclear field shift effect is larger in Δ199Hg than in Δ201Hg by approximately a factor of two. The predominant mercury chemical species in fish is methylmercury cysteine. From the experimental studies of Buchachenko and others (2004) on the reaction of methylmercury chloride with creatine kinase it seems reasonable to predicted that the thiol functional groups of cysteine gets enriched in 199Hg and 201Hg. Here the magnetic isotope effect (MIE) produces a kinetic partial separation of isotopes with non-zero nuclear spin quantum numbers from the even-N isotopes. The ratio of enrichment of Δ201Hg /Δ199Hg is predicted from theory to be 1.11, which is the ratio of the magnetic moments of 199Hg and 201Hg. Because mercury possesses two odd-N isotopes, it is possible to detect and evaluate the effects of two distinct, mass-independent isotope fractionating processes. From the data obtained on fish samples, we can deconvolute the contributions of the isotope effects of nuclear mass, spin and volume. For these samples the role of spin or the magnetic isotope effect is the most dominant.
Microchemostat array with small-volume fraction replenishment for steady-state microbial culture.
Park, Jaewon; Wu, Jianzhang; Polymenis, Michael; Han, Arum
2013-11-07
A chemostat is a bioreactor in which microorganisms can be cultured at steady-state by controlling the rate of culture medium inflow and waste outflow, thus maintaining media composition over time. Even though many microbial studies could greatly benefit from studying microbes in steady-state conditions, high instrument cost, complexity, and large reagent consumption hamper the routine use of chemostats. Microfluidic-based chemostats (i.e. microchemostats) can operate with significantly smaller reagent consumption while providing accurate chemostatic conditions at orders of magnitude lower cost compared to conventional chemostats. Also, microchemostats have the potential to significantly increase the throughput by integrating arrays of microchemostats. We present a microchemostat array with a unique two-depth culture chamber design that enables small-volume fraction replenishment of culture medium as low as 1% per replenishment cycle in a 250 nl volume. A system having an array of 8 microchemostats on a 40 × 60 mm(2) footprint could be automatically operated in parallel by a single controller unit as a demonstration for potential high throughput microbial studies. The model organism, Saccharomyces cerevisiae, successfully reached a stable steady-state of different cell densities as a demonstration of the chemostatic functionality by programming the dilution rates. Chemostatic functionality of the system was further confirmed by quantifying the budding index as a function of dilution rate, a strong indicator of growth-dependent cell division. In addition, the small-volume fraction replenishment feature minimized the cell density fluctuation during the culture. The developed system provides a robust, low-cost, and higher throughput solution to furthering studies in microbial physiology.
Constraining the Variability and Binary Fraction of Galactic Center Young Stars
Gautam, Abhimat K; Ghez, Andrea M; Lu, Jessica R; Morris, Mark R; Sakai, Shoko; Witzel, Gunther; Sitarski, Breann N; Chappell, Samantha
2016-01-01
We present constraints on the variability and binarity of young stars in the central 10 arcseconds (~0.4 pc) of the Milky Way Galactic Center (GC) using Keck Adaptive Optics data over a 12 year baseline. Given our experiment's photometric uncertainties, at least 36% of our sample's known early-type stars are variable. We identified eclipsing binary systems by searching for periodic variability. In our sample of spectroscopically confirmed and likely early-type stars, we detected the two previously discovered GC eclipsing binary systems. We derived the likely binary fraction of main sequence, early-type stars at the GC via Monte Carlo simulations of eclipsing binary systems, and find that it is at least 32% with 90% confidence.
Kandasamy, R.; Jeyabalan, C.; Sivagnana Prabhu, K. K.
2016-02-01
This article examines the influence of thermophoresis, Brownian motion of the nanoparticles with variable stream conditions in the presence of magnetic field on mixed convection heat and mass transfer in the boundary layer region of a semi-infinite porous vertical plate in a nanofluid under the convective boundary conditions. The transformed boundary layer ordinary differential equations are solved numerically using Maple 18 software with fourth-fifth order Runge-Kutta-Fehlberg method. Numerical results are presented both in tabular and graphical forms illustrating the effects of these parameters with magnetic field on momentum, thermal, nanoparticle volume fraction and solutal concentration boundary layers. The numerical results obtained for the velocity, temperature, volume fraction, and concentration profiles reveal interesting phenomenon, some of these qualitative results are presented through plots. It is interesting to note that the magnetic field plays a dominant role on nanofluid flow under the convective boundary conditions.
Pinnola, Francesco Paolo
2016-10-01
The statistical characterization of the oscillator response with non-integer order damping under Gaussian noise represents an important challenge in the modern stochastic mechanics. In fact, this kind of problem appears in several issues of different type (wave propagation in viscoelastic media, Brownian motion, fluid dynamics, RLC circuit, etc.). The aim of this paper is to provide a stochastic characterization of the stationary response of linear fractional oscillator forced by normal white noise. In particular, this paper shows a new method to obtain the correlation function by exact complex spectral moments. These complex quantities contain all the information to describe the random processes but in the considered case their analytical evaluation needs some mathematical manipulations. For this reason such complex spectral moment characterization is used in conjunction with a fractional-order state variable analysis. This kind of analysis permits to find the exact expression of complex spectral moments, and the correlation function by using the Mellin transform. Moreover, the proposed approach provides an analytical expression of the response variance of the fractional oscillator. Capability and efficiency of the present method are shown in the numerical examples in which correlation and variance of fractional oscillator response are found and compared with those obtained by Monte Carlo simulations.
Garcia-Lazaro, Haydee Guadalupe; Becerra-Laparra, Ivonne; Cortez-Conradis, David; Roldan-Valadez, Ernesto
2016-01-01
Summary Several parameters of brain integrity can be derived from diffusion tensor imaging. These include fractional anisotropy (FA) and mean diffusivity (MD). Combination of these variables using multivariate analysis might result in a predictive model able to detect the structural changes of human brain aging. Our aim was to discriminate between young and older healthy brains by combining structural and volumetric variables from brain MRI: FA, MD, and white matter (WM), gray matter (GM) and cerebrospinal fluid (CSF) volumes. This was a cross-sectional study in 21 young (mean age, 25.71±3.04 years; range, 21–34 years) and 10 elderly (mean age, 70.20±4.02 years; range, 66–80 years) healthy volunteers. Multivariate discriminant analysis, with age as the dependent variable and WM, GM and CSF volumes, global FA and MD, and gender as the independent variables, was used to assemble a predictive model. The resulting model was able to differentiate between young and older brains: Wilks’ λ = 0.235, χ2 (6) = 37.603, p = .000001. Only global FA, WM volume and CSF volume significantly discriminated between groups. The total accuracy was 93.5%; the sensitivity, specificity and positive and negative predictive values were 91.30%, 100%, 100% and 80%, respectively. Global FA, WM volume and CSF volume are parameters that, when combined, reliably discriminate between young and older brains. A decrease in FA is the strongest predictor of membership of the older brain group, followed by an increase in WM and CSF volumes. Brain assessment using a predictive model might allow the follow-up of selected cases that deviate from normal aging. PMID:27027893
Institute of Scientific and Technical Information of China (English)
无
2010-01-01
In this paper, the feasibility of measuring the gas volume fraction in a mixed gas-liquid flow by using an acoustic resonant spectroscopy (ARS) method in a transient way is studied theoretically and experimentally. Firstly, the effects of sizes and locations of a single air bubble in a cylindrical cavity with two open ends on resonant frequencies are investigated numerically. Then, a transient measurement system for ARS is established, and the trends of the resonant frequencies (RFs) and resonant amplitudes (RAs) in the cylindrical cavity with gas flux inside are investigated experimentally. The measurement results by the proposed transient method are compared with those by steady-state ones and numerical ones. The numerical results show that the RFs of the cavity are highly sensitive to the volume of the single air bubble. A tiny bubble volume perturbation may cause a prominent RF shift even though the volume of the air bubble is smaller than 0.1% of that of the cavity. When the small air bubble moves, the RF shift will change and reach its maximum value as it is located at the middle of the cavity. As the gas volume fraction of the two-phase flow is low, both the RFs and RAs from the measurement results decrease dramatically with the increasing gas volume, and this decreasing trend gradually becomes even as the gas volume fraction increases further. These experimental results agree with the theoretical ones qualitatively. In addition, the transient method for ARS is more suitable for measuring the gas volume fraction with randomness and instantaneity than the steady-state one, because the latter could not reflect the random and instant characteristics of the mixed fluid due to the time consumption for frequency sweeping. This study will play a very important role in the quantitative measurement of the gas volume fraction of multiphase flows.
MHD flow of dusty nanofluid over a stretching surface with volume fraction of dust particles
Directory of Open Access Journals (Sweden)
Sandeep Naramgari
2016-06-01
Full Text Available In this study we analyzed the momentum and heat transfer behavior of MHD nanofluid embedded with conducting dust particles past a stretching surface in the presence of volume fraction of dust particles. The governing equations of the flow and heat transfer are transformed into nonlinear ordinary differential equations by using similarity transformation and then solved numerically using Runge–Kutta based shooting technique. The effect of non-dimensional governing parameters on velocity and temperature profiles of the flow are discussed and presented through graphs. Additionally friction factor and the Nusselt number have also been computed. Under some special conditions, numerical results obtained by the present study were compared with the existed studies. The result of the present study proves to be highly satisfactory. The results indicate that an increase in the interaction between the fluid and particle phase enhances the heat transfer rate and reduces the friction factor.
Volume fraction instability in an oscillating non-Brownian iso-dense suspension.
Roht, Y. L.; Gauthier, G.; Hulin, J. P.; Salin, D.; Chertcoff, R.; Auradou, H.; Ippolito, I.
2017-06-01
The instability of an iso-dense non-Brownian suspension of polystyrene beads of diameter 40 μm dispersed in a water-glycerol mixture submitted to a periodic square wave oscillating flow in a Hele-Shaw cell is studied experimentally. The instability gives rise to stationary bead concentration waves transverse to the flow. It has been observed for average particle volume fractions between 0.25 and 0.4, for periods of the square wave flow variation between 0.4 and 10 s and in finite intervals of the amplitude of the fluid displacement. The study shows that the wavelength λ increases roughly linearly with the amplitude of the oscillatory flow; on the other hand, λ is independent of the particle concentration and of the period of oscillation of the flow although the minimum threshold amplitude for observing the instability increases with the period.
Makarov, C; Gotman, I; Jiang, X; Fuchs, S; Kirkpatrick, C J; Gutmanas, E Y
2010-06-01
Biodegradable calcium phosphate-PCL nanocomposite powders with unusually high ceramic volume fractions (80-95%) and uniform PCL distribution were synthesized by a non-aqueous chemical reaction in the presence of the dissolved polymer. No visible polymer separation occurred during processing. Depending on the reagents combination, either dicalcium phosphate (DCP) or Ca-deficient HA (CDHA) was obtained. CDHA-PCL composite powders were high pressure consolidated at room temperature yielding dense materials with high compressive strengths. Such densification route provides the possibility of incorporating drug and proteins without damaging their biological activity. The CDHA-PCL composites were tested in osteoblastic and endothelial cell line cultures and were found to support the attachment and proliferation of both cell types.
Mechanical behavior of LC4 alloy in semisolid state at high volume fractions of solid
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
The mechanical behavior of LC4 alloy in the semisolid state at high volume fractions of solid has been studied through unconstrictive compressing test. The results show that peak stress mainly depends on grain boundary's cohesion and instantaneous strain rate sensitivity in the semisolid state, which is similar to that in the solid state. Analyses on microstructures and status of compressive stress of specimen demonstrate that segregation of liquid-solid phase is mainly affected by strain rate and deformation temperature. There are mainly two kinds of flow in liquid phase: either from the region with relatively large hydrostatic compressive stress to the region with relatively small hydrostatic compressive stress or from the grain boundaries perpendicular to the compression axis to the grain boundaries with a certain directional angle to the compression direction. Based on the above results, compressive deformation mechanism mainly depends on deformation temperature, strain rate and stress state.
Rice, M E; Nicholson, C
1991-02-01
1. Diffusion properties of submerged, superfused slices from the rat neostriatum were measured by quantitative analysis of concentration-time profiles of tetramethylammonium (TMA+) introduced by iontophoresis. TMA+ was sensed at an ion-selective microelectrode (ISM) positioned 100-150 microns from the source pipette. Slice viability was assessed from the extracellular field potentials evoked by intrastriatal electrical stimulation. 2. Under normoxic conditions the extracellular volume fraction (alpha) was 0.21 (range 0.18-0.24), and the tortuosity (lambda) was 1.54, in slices with good field potentials. In slices with poor field potentials, alpha was 0.09-0.16. Extraction of correct alpha and lambda in the slice required evaluation of nonspecific uptake, k', which was 1 x 10(-2) s-1. 3. Slices were made hypoxic by superfusing physiological saline equilibrated with 95% N2-5% CO2 for 10-30 min. Synaptic components of field potentials were inhibited after 3-4 min in hypoxic media. In some experiments extracellular K+ concentration [( K+]o) was monitored with ISMs. During hypoxia, [K+]o rose from an average baseline of 5.1 mM to 7-10 mM. After reoxygenation, [K+]o transiently fell below the original level. 4. The average value for alpha during hypoxia was 0.13 (a 38% decrease), which was significantly different from control (P less than 0.001) and increased progressively during hypoxic exposure. In contrast, tortuosity and k' were unchanged by this treatment. 5. These data represent the first characterization of the diffusion properties of the rat striatal slice and of changes in extracellular volume fraction during hypoxia in a brain slice preparation.(ABSTRACT TRUNCATED AT 250 WORDS)
Energy Technology Data Exchange (ETDEWEB)
Gama, Adriana M., E-mail: adrianaamg@iae.cta.br [Divisao de Materiais (AMR), Instituto de Aeronautica e Espaco (IAE), Departamento de Ciencia e Tecnologia Aeroespacial - DCTA (Brazil); Rezende, Mirabel C., E-mail: mirabelmcr@iae.cta.br [Divisao de Materiais (AMR), Instituto de Aeronautica e Espaco (IAE), Departamento de Ciencia e Tecnologia Aeroespacial - DCTA (Brazil); Dantas, Christine C., E-mail: christineccd@iae.cta.br [Divisao de Materiais (AMR), Instituto de Aeronautica e Espaco (IAE), Departamento de Ciencia e Tecnologia Aeroespacial - DCTA (Brazil)
2011-11-15
We report the analysis of measurements of the complex magnetic permeability ({mu}{sub r}) and dielectric permittivity ({epsilon}{sub r}) spectra of a rubber radar absorbing material (RAM) with various MnZn ferrite volume fractions. The transmission/reflection measurements were carried out in a vector network analyzer. Optimum conditions for the maximum microwave absorption were determined by substituting the complex permeability and permittivity in the impedance matching equation. Both the MnZn ferrite content and the RAM thickness effects on the microwave absorption properties, in the frequency range of 2-18 GHz, were evaluated. The results show that the complex permeability and permittivity spectra of the RAM increase directly with the ferrite volume fraction. Reflection loss calculations by the impedance matching degree (reflection coefficient) show the dependence of this parameter on both thickness and composition of RAM. - Highlights: > Permeability and permittivity spectra of a MnZn ferrite RAM (2-18 GHz) are given. > Higher MnZn volume fraction favors increase of RAM/'s permeability and permittivity. > Minimum RL as a function of frequency, thickness and MnZn volume fraction given. > Higher thicknesses imply better absorption; optimum band shifts to lower frequencies. > For higher volume fractions, smaller thickness might offer better absorption (>10 GHz).
Directory of Open Access Journals (Sweden)
Mohammed Sellab Hamza
2008-01-01
Full Text Available In this study the effect of fiber volume fraction of the glass fiber on the thermal conductivity of the polymer composite material was studied. Different fiber volume fraction of glass fibers were used (3%, 6%, 9%, 12%, and 15%. Specimens were made from polyester which reinforced with glass fibers .The fibers had two arrangements according to the direction of the thermal flow. In the first arrangement the fibers were parallel to the direction of the thermal flow, while the second arrangement was perpendicular; Lee's disk method was used for testing the specimens. The experimental results proved that the values of the thermal conductivity of the specimens was higher when the fibers arranged in parallel direction than that when the fibers arranged in the perpendicular direction. The percentage of increasing of experimental thermal conductivity was 96.91% for parallel arrangement and 13.33% for perpendicular arrangement comparison with its original value before the using of glass fibers. Also the experimental results indicated that the thermal conductivity increases with the increasing of the fiber volume fraction. Minimum value was (0.172 W/m.C for perpendicular arrangement at fiber volume fraction 3% and maximum value was (0.327 W/m.C for parallel arrangement at fiber volume fraction 15%.
RESOLVE Survey Photometry and Volume-limited Calibration of the Photometric Gas Fractions Technique
Eckert, Kathleen D; Stark, David V; Moffett, Amanda J; Norris, Mark A; Snyder, Elaine M; Hoversten, Erik A
2015-01-01
We present custom-processed UV, optical, and near-IR photometry for the RESOLVE survey, a volume-limited census of stellar, gas, and dynamical mass within two subvolumes of the nearby universe (RESOLVE-A and -B), complete down to baryonic mass ~10^9.1-9.3 Msun. In contrast to standard pipeline photometry (e.g., SDSS), our photometry uses optimal background subtraction, avoids suppressing color gradients, and includes systematic errors. With these improvements, we measure brighter magnitudes, larger radii, bluer colors, and a real increase in scatter around the red sequence. Combining stellar masses from our photometry with the RESOLVE-A HI mass census, we create volume-limited calibrations of the photometric gas fractions (PGF) technique, which predicts gas-to-stellar mass ratios (G/S) from galaxy colors and optional additional parameters. We analyze G/S-color residuals vs. potential third parameters, finding that axial ratio is the best independent and physically meaningful third parameter. We define a "modi...
Badea, Anamaria Raluca; Nedelcu, Laurentiu; Valeanu, Madalina; Zdrenghea, Dumitru
2014-01-01
The aim of this study is to identify and highlight the relationship between serum lipid fractions and heart rate variability in diabetic patients receiving statin therapy. The study was performed in a group of 87 type 2 diabetic patients on statin associated therapy. All patients were on Holter ECG 24 hours monitored with three channel monitor (Labtech ECG Holter monitor), and data were analyzed on a commercially available software (Cardiospy PC SW/EV 5.02.06.02). Concentrations of biochemical parameters were determined using specific enzymatic assays on an autoanalyzer Olympus AU 680. In the studied patients, we analyzed Holter/24 hours monitoring reports with respect to heart rate variability indexes, arrhythmic events and myocardial ischemia. It was noticed that the mean values of serum TG were slightly elevated, TC levels were close to the limits specified by the guidelines for diabetic patients and for patients with cardiovascular diseases, with no significant differences between males and females. After analyzing the HRV in both time and frequency domains, we found no strong correlations between any of the HRV indexes and any of the lipid fractions. The results suggest that statin therapy may reduce the autonomic impairment secondary to dyslipidemia.
Elastic modulus of Al-Si/SiC metal matrix composites as a function of volume fraction
Energy Technology Data Exchange (ETDEWEB)
Santhosh Kumar, S; Rajasekharan, T [Powder Metallurgy Group, Defence Metallurgical Research Laboratory, Kanchanbagh PO, Hyderabad-500 058 (India); Seshu Bai, V [School of Physics, University of Hyderabad, Central University PO, Hyderabad-500 046 (India); Rajkumar, K V; Sharma, G K; Jayakumar, T, E-mail: dearsanthosh@gmail.co [Non-Destructive Evaluation Division, Indira Gandhi Center for Atomic Research, Kalpakkam, Chennai-603 102 (India)
2009-09-07
Aluminum alloy matrix composites have emerged as candidate materials for electronic packaging applications in the field of aerospace semiconductor electronics. Composites prepared by the pressureless infiltration technique with high volume fractions in the range 0.41-0.70 were studied using ultrasonic velocity measurements. For different volume fractions of SiC, the longitudinal velocity and shear velocity were found to be in the range of 7600-9300 m s{sup -1} and 4400-5500 m s{sup -1}, respectively. The elastic moduli of the composites were determined from ultrasonic velocities and were analysed as a function of the volume fraction of the reinforcement. The observed variation is discussed in the context of existing theoretical models for the effective elastic moduli of two-phase systems.
DEFF Research Database (Denmark)
Poulsen, Stefan Othmar; Voorhees, P.W.; Lauridsen, Erik Mejdal
2013-01-01
The microstructural evolution of a polycrystalline dual-phase material with a constant volume fraction of the phases was investigated using large-scale three-dimensional phase-field simulations. All materials parameters are taken to be isotropic, and microstructures with volume fractions of 50....../50 and 40/60 were examined. After an initial transient, the number of grains decrease from ∼2600 to ∼500. It was found that the mean grain size of grains of both phases obeyed a power law with an exponent of 3, and the microstructural evolution was found to be controlled by diffusion. Steady...... with the topology of single-phase grain structures as determined by experiment and simulation. The evolution of size and number of faces for the minority and majority phase grains in the 40/60 volume fraction simulation is presented and discussed. Non-constant curvature across some interphase boundaries...
Institute of Scientific and Technical Information of China (English)
Yu Shu; Min Wang
2015-01-01
In this paper, we prove the boundedness of the fractional maximal opera-tor, Hardy-Littlewood maximal operator and marcinkiewicz integrals associated with Schr ¨odinger operator on Morrey spaces with variable exponent.
Emergent Chemical Behavior in Variable-Volume Protocells
Shirt-Ediss, Ben; Solé, Ricard V.; Ruiz-Mirazo, Kepa
2015-01-01
Artificial protocellular compartments and lipid vesicles have been used as model systems to understand the origins and requirements for early cells, as well as to design encapsulated reactors for biotechnology. One prominent feature of vesicles is the semi-permeable nature of their membranes, able to support passive diffusion of individual solute species into/out of the compartment, in addition to an osmotic water flow in the opposite direction to the net solute concentration gradient. Crucially, this water flow affects the internal aqueous volume of the vesicle in response to osmotic imbalances, in particular those created by ongoing reactions within the system. In this theoretical study, we pay attention to this often overlooked aspect and show, via the use of a simple semi-spatial vesicle reactor model, that a changing solvent volume introduces interesting non-linearities into an encapsulated chemistry. Focusing on bistability, we demonstrate how a changing volume compartment can degenerate existing bistable reactions, but also promote emergent bistability from very simple reactions, which are not bistable in bulk conditions. One particularly remarkable effect is that two or more chemically-independent reactions, with mutually exclusive reaction kinetics, are able to couple their dynamics through the variation of solvent volume inside the vesicle. Our results suggest that other chemical innovations should be expected when more realistic and active properties of protocellular compartments are taken into account. PMID:25590570
Emergent chemical behavior in variable-volume protocells.
Shirt-Ediss, Ben; Solé, Ricard V; Ruiz-Mirazo, Kepa
2015-01-13
Artificial protocellular compartments and lipid vesicles have been used as model systems to understand the origins and requirements for early cells, as well as to design encapsulated reactors for biotechnology. One prominent feature of vesicles is the semi-permeable nature of their membranes, able to support passive diffusion of individual solute species into/out of the compartment, in addition to an osmotic water flow in the opposite direction to the net solute concentration gradient. Crucially, this water flow affects the internal aqueous volume of the vesicle in response to osmotic imbalances, in particular those created by ongoing reactions within the system. In this theoretical study, we pay attention to this often overlooked aspect and show, via the use of a simple semi-spatial vesicle reactor model, that a changing solvent volume introduces interesting non-linearities into an encapsulated chemistry. Focusing on bistability, we demonstrate how a changing volume compartment can degenerate existing bistable reactions, but also promote emergent bistability from very simple reactions, which are not bistable in bulk conditions. One particularly remarkable effect is that two or more chemically-independent reactions, with mutually exclusive reaction kinetics, are able to couple their dynamics through the variation of solvent volume inside the vesicle. Our results suggest that other chemical innovations should be expected when more realistic and active properties of protocellular compartments are taken into account.
Emergent Chemical Behavior in Variable-Volume Protocells
Directory of Open Access Journals (Sweden)
Ben Shirt-Ediss
2015-01-01
Full Text Available Artificial protocellular compartments and lipid vesicles have been used as model systems to understand the origins and requirements for early cells, as well as to design encapsulated reactors for biotechnology. One prominent feature of vesicles is the semi-permeable nature of their membranes, able to support passive diffusion of individual solute species into/out of the compartment, in addition to an osmotic water flow in the opposite direction to the net solute concentration gradient. Crucially, this water flow affects the internal aqueous volume of the vesicle in response to osmotic imbalances, in particular those created by ongoing reactions within the system. In this theoretical study, we pay attention to this often overlooked aspect and show, via the use of a simple semi-spatial vesicle reactor model, that a changing solvent volume introduces interesting non-linearities into an encapsulated chemistry. Focusing on bistability, we demonstrate how a changing volume compartment can degenerate existing bistable reactions, but also promote emergent bistability from very simple reactions, which are not bistable in bulk conditions. One particularly remarkable effect is that two or more chemically-independent reactions, with mutually exclusive reaction kinetics, are able to couple their dynamics through the variation of solvent volume inside the vesicle. Our results suggest that other chemical innovations should be expected when more realistic and active properties of protocellular compartments are taken into account.
Karssemakers, L H E; Nolte, J W; Tuinzing, D B; Langenbach, G E J; Raijmakers, P G; Becking, A G
2014-12-01
Unilateral condylar hyperplasia or hyperactivity is a disorder of growth that affects the mandible, and our aim was to visualise the 3-dimensional bony microstructure of resected mandibular condyles of affected patients. We prospectively studied 17 patients with a clinical presentation of progressive mandibular asymmetry and an abnormal single-photon emission computed tomographic (SPECT) scan. All patients were treated by condylectomy to arrest progression. The resected condyles were scanned with micro-CT (18 μm resolution). Rectangular volumes of interest were selected in 4 quadrants (lateromedial and superoinferior) of the trabecular bone of each condyle. Variables of bone architecture (volume fraction, trabecular number, thickness, and separation, degree of mineralisation, and degree of structural anisotrophy) were calculated with routine morphometric software. Eight of the 17 resected condyles showed clear destruction of the subchondral layer of cortical bone. There was a significant superoinferior gradient for all trabecular variables. Mean (SD) bone volume fraction (25.1 (6) %), trabecular number (1.69 (0.26) mm(-1)), trabecular thickness (0.17 (0.03) mm), and degree of mineralisation (695.39 (39.83) mg HA/cm(3)) were higher in the superior region. Trabecular separation (0.6 (0.16) mm) and structural anisotropy (1.84 (0.28)) were higher in the inferior region. The micro-CT analysis showed increased cortical porosity in many of the condyles studied. It also showed a higher bone volume fraction, greater trabecular thickness and trabecular separation, greater trabecular number, and less mineralisation in the condyles of the 17 patients compared with the known architecture of unaffected mandibular condyles.
Institute of Scientific and Technical Information of China (English)
LEI Wen-guang; REN Chao
2006-01-01
Ramie cloth/UP resin composite was formed at 0.2 MPa and cured at room temperature for 24 h and treated at 80 ℃ for2 h. The physical and mechanical properties of the composites with different volume fractions of ramie cloth were studied. The results show that,with the increase of the volume fraction of the ramie cloth,densities of the composites become greater and greater,though all lower than the theoretical values,the linear shrinkage during the formation decreases from 1.20% of the original UP resin to 0.18% of the composite with 30% of ramie cloth in volume,all the composites also absorb more water than UP resin casting,greater volume fraction of the fiber,more water will be absorbed,but the increase in water absorption becomes smaller and smaller with time. As regards some mechanical properties,the tensile strength,flexural strength,flexural modulus and impact strength are all improved when more ramie fiber is added. Compared with those of pure UP resin casting,the mechanical properties are increased by 93.93%,76.20%,190.18% and 227.26% respectively when the volume fraction of the ramie cloth in the composite is 30%. The differential scanning calorimetry results show that only one peak will appear for the sample without or with less ramie fiber while two peaks will appear when more ramie cloth is added.
2012-07-01
increasing the fiber-volume fraction by vacuum-assisted resin transfer molding ( VARTM ) in order to produce composite structures with aerospace-grade...processed composites. Using a combination of viscosity control, ARL- based VARTM techniques, and a pressure control system, we increased the fiber-volume...content from 50% (ARL’s normal processing range for a particular material system and VARTM process) to over 60%. Future work will focus on
Institute of Scientific and Technical Information of China (English)
金江丽
2014-01-01
Objective To investigate the relationship of blood pressure variability(BPV)and heart rate variability(HRV)with prostatic volume(PV)in patients with benign prostatic hyperplasia(BPH).Methods A total of133 patients admitted to our department between January2011 and April 2013 were analyzed retrospectively.The patients were divided into BPH group and non-BPH group according to the PV value.The ambulatory blood
Quantification and variability in colonic volume with a novel magnetic resonance imaging method
DEFF Research Database (Denmark)
Nilsson, M; Sandberg, Thomas Holm; Poulsen, Jakob Lykke;
2015-01-01
-individual and intra-individual variability of segmental colorectal volumes between two observations in healthy subjects and (ii) the change in segmental colorectal volume distribution before and after defecation. Methods: The inter-individual and intra-individual variability of four colorectal volumes (cecum...... observations were detected for any segments (All p > 0.05). Inter-individual variability varied across segments from low correlation in cecum/ascending colon (intra-class correlation coefficient [ICC] = 0.44) to moderate correlation in the descending colon (ICC = 0.61) and high correlation in the transverse...... (p = 0.02). Conclusions & Inferences: Imaging of segmental colorectal volume, morphology, and fecal accumulation is advantageous to conventional methods in its low variability, high spatial resolution, and its absence of contrast-enhancing agents and irradiation. Hence, the method is suitable...
Mineralogy of the clay fraction of Alfisols in two slope curvatures: III - spatial variability
Directory of Open Access Journals (Sweden)
Livia Arantes Camargo
2013-04-01
Full Text Available A good knowledge of the spatial distribution of clay minerals in the landscape facilitates the understanding of the influence of relief on the content and crystallographic attributes of soil minerals such as goethite, hematite, kaolinite and gibbsite. This study aimed at describing the relationships between the mineral properties of the clay fraction and landscape shapes by determining the mineral properties of goethite, hematite, kaolinite and gibbsite, and assessing their dependence and spatial variability, in two slope curvatures. To this end, two 100 × 100 m grids were used to establish a total of 121 regularly spaced georeferenced sampling nodes 10 m apart. Samples were collected from the layer 0.0-0.2 m and analysed for iron oxides, and kaolinite and gibbsite in the clay fraction. Minerals in the clay fraction were characterized from their X-ray diffraction (XRD patterns, which were interpreted and used to calculate the width at half height (WHH and mean crystallite dimension (MCD of iron oxides, kaolinite, and gibbsite, as well as aluminium substitution and specific surface area (SSA in hematite and goethite. Additional calculations included the goethite and hematite contents, and the goethite/(goethite+hematite [Gt/(Gt+Hm] and kaolinite/(kaolinite+gibbsite [Kt/(Kt+Gb] ratios. Mineral properties were established by statistical analysis of the XRD data, and spatial dependence was assessed geostatistically. Mineralogical properties differed significantly between the convex area and concave area. The geostatistical analysis showed a greater number of mineralogical properties with spatial dependence and a higher range in the convex than in the concave area.
A Stochastic Fractional Dynamics Model of Space-time Variability of Rain
Kundu, Prasun K.; Travis, James E.
2013-01-01
Rainfall varies in space and time in a highly irregular manner and is described naturally in terms of a stochastic process. A characteristic feature of rainfall statistics is that they depend strongly on the space-time scales over which rain data are averaged. A spectral model of precipitation has been developed based on a stochastic differential equation of fractional order for the point rain rate, that allows a concise description of the second moment statistics of rain at any prescribed space-time averaging scale. The model is thus capable of providing a unified description of the statistics of both radar and rain gauge data. The underlying dynamical equation can be expressed in terms of space-time derivatives of fractional orders that are adjusted together with other model parameters to fit the data. The form of the resulting spectrum gives the model adequate flexibility to capture the subtle interplay between the spatial and temporal scales of variability of rain but strongly constrains the predicted statistical behavior as a function of the averaging length and times scales. We test the model with radar and gauge data collected contemporaneously at the NASA TRMM ground validation sites located near Melbourne, Florida and in Kwajalein Atoll, Marshall Islands in the tropical Pacific. We estimate the parameters by tuning them to the second moment statistics of radar data. The model predictions are then found to fit the second moment statistics of the gauge data reasonably well without any further adjustment.
Bahaya, Bernard
The aim of this thesis is to study the improvement of heat transfer in graphene-water nanofluids. Experiments were conducted with graphene nanoplatelets (GNP) to study the relative benefit of the thermal conductivity improvement in relationship to the potential detriment when considering the effect that more GNP dispersed in the water increases the viscosity of the resulting suspension relative to that of the water. A maximum enhancement ratio for GNP nanofluid thermal conductivity over water was 1.43 at a volume fraction of 0.014. Based upon GNP aspect ratios confirmed in sizing measurements, the DEM model presented by Chu et al., (2012) appears to describe the experimental results of this study when using a fitted interfacial resistance value of 6.25 E -8 m2 K W-1. The well-known Einstein viscosity model for spheres dispersed in fluids was shown to under predict the experimental data. Adjusting the intrinsic model term for spheres from a value of 2.5 to a fitted value of 1938 representative for the GNP of this study provided much closer agreement between measured and predicted values. Heat transfer is a nonlinear function of viscosity and thermal conductivity and heat transfer is predicted to decrease for GNP nanofluids when compared to water alone. Hence the use of nanofluids to enhance heat transfer processes appears not to be viable.
Properties of High Volume Fraction Fly Ash/Al Alloy Composites Produced by Infiltration Process
Kountouras, D. T.; Stergioudi, F.; Tsouknidas, A.; Vogiatzis, C. A.; Skolianos, S. M.
2015-09-01
In the present study, pressure infiltration is employed to synthesize aluminum alloy 7075-fly ash composites. The microstructure and chemical composition of the fly ash and the produced composite material was examined using optical and scanning electron microscopy, as well as x-ray diffraction. Several properties of the produced composite material were examined and evaluated including macro-hardness, wear, thermal expansion, and corrosion behavior. The wear characteristics of the composite, in the as-cast conditions, were studied by dry sliding wear tests. The corrosion behavior of composite material was evaluated by means of potentiodynamic corrosion experiments in a 3.5 wt.% NaCl solution. The composite specimens exhibit a homogeneous distribution of fly ash particles and present enhanced hardness values, compared to the matrix material. The high volume fraction of the fly ash reinforcement (>40%) in the composite material led to increased wear rates, attributed to the fragmentation of the fly ash particles. However, the presence of fly ash particles in the Al alloy matrix considerably decreased the coefficiency of thermal expansion, while resulting in an altered corrosion mechanism of the composite material with respect to the matrix alloy.
Mapping Bone Mineral Density Obtained by Quantitative Computed Tomography to Bone Volume Fraction
Pennline, James A.; Mulugeta, Lealem
2017-01-01
Methods for relating or mapping estimates of volumetric Bone Mineral Density (vBMD) obtained by Quantitative Computed Tomography to Bone Volume Fraction (BVF) are outlined mathematically. The methods are based on definitions of bone properties, cited experimental studies and regression relations derived from them for trabecular bone in the proximal femur. Using an experimental range of values in the intertrochanteric region obtained from male and female human subjects, age 18 to 49, the BVF values calculated from four different methods were compared to the experimental average and numerical range. The BVF values computed from the conversion method used data from two sources. One source provided pre bed rest vBMD values in the intertrochanteric region from 24 bed rest subject who participated in a 70 day study. Another source contained preflight vBMD values from 18 astronauts who spent 4 to 6 months on the ISS. To aid the use of a mapping from BMD to BVF, the discussion includes how to formulate them for purpose of computational modeling. An application of the conversions would be used to aid in modeling of time varying changes in vBMD as it relates to changes in BVF via bone remodeling and/or modeling.
Jovin, Ion S; Ebisu, Keita; Liu, Yi-Hwa; Finta, Laurie A; Oprea, Adriana D; Brandt, Cynthia A; Dziura, James; Wackers, Frans J
2013-01-01
Diastolic dysfunction can be diagnosed on equilibrium radionuclide angiocardiography (ERNA) by a low peak filling rate (PFR) in the setting of a normal left ventricular ejection fraction (LVEF). The authors evaluated the relationship between diastolic dysfunction, LVEF, and end-diastolic volume (EDV). A total of 408 predominantly asymptomatic patients with an LVEF ≥50% by ERNA were studied. LVEF of patients with a low PFR was compared with the LVEF of patients with a normal PFR. Correlation analyses to evaluate the association between PFR and EDV were also performed. The LVEF of patients with a low PFR was lower than the LVEF of patients with normal PFR (59±7 vs 63%±7%; PPFR (r=-0.04; P=.32). The results did not change when the EDV indices were used. In patients who had repeat scans, there was no correlation between the change in EDV and the change in PFR (r=0.16; P=.2). In asymptomatic patients undergoing ERNA who have normal systolic function, a low PFR can be associated with a lower LVEF, but it is not associated with changes in EDV. This suggests that diastolic dysfunction is associated with mild systolic dysfunction.
A framework of whole heart extracellular volume fraction estimation for low-dose cardiac CT images.
Chen, Xinjian; Nacif, Marcelo S; Liu, Songtao; Sibley, Christopher; Summers, Ronald M; Bluemke, David A; Yao, Jianhua
2012-09-01
Cardiac CT (CCT) is widely available and has been validated for the detection of focal myocardial scar using a delayed enhancement technique in this paper. CCT, however, has not been previously evaluated for quantification of diffuse myocardial fibrosis. In our investigation, we sought to evaluate the potential of low-dose CCT for the measurement of myocardial whole heart extracellular volume (ECV) fraction. ECV is altered under conditions of increased myocardial fibrosis. A framework consisting of three main steps was proposed for CCT whole heart ECV estimation. First, a shape-constrained graph cut (GC) method was proposed for myocardium and blood pool segmentation on postcontrast image. Second, the symmetric demons deformable registration method was applied to register precontrast to postcontrast images. So the correspondences between the voxels from precontrast to postcontrast images were established. Finally, the whole heart ECV value was computed. The proposed method was tested on 20 clinical low-dose CCT datasets with precontrast and postcontrast images. The preliminary results demonstrated the feasibility and efficiency of the proposed method.
Role of cardiac CTA in estimating left ventricular volumes and ejection fraction
Institute of Scientific and Technical Information of China (English)
Robin; Man; Singh; Balkrishna; Man; Singh; Jawahar; Lal; Mehta
2014-01-01
Left ventricular ejection fraction(LVEF)is an impor-tant predictor of cardiac outcome and helps in makingimportant diagnostic and therapeutic decisions suchas the treatment of different types of congestive heartfailure or implantation of devices like cardiac resynchro-nization therapy-defibrillator.LVEF can be measuredby various techniques such as transthoracic echo-cardiography,contrast ventriculography,radionuclidetechniques,cardiac magnetic resonance imaging andcardiac computed tomographic angiography(CTA).Thedevelopment of cardiac CTA using multi-detector rowCT(MDCT)has seen a very rapid improvement in thetechnology for identifying coronary artery stenosis andcoronary artery disease in the last decade.During theacquisition,processing and analysis of data to studycoronary anatomy,MDCT provides a unique opportunityto measure left ventricular volumes and LVEF simulta-neously with the same data set without the need foradditional contrast or radiation exposure.The develop-ment of semi-automated and automated software to measure LVEF has now added uniformity,efficiency and reproducibility of practical value in clinical practice rather than just being a research tool.This article will address the feasibility,the accuracy and the limitations of MDCT in measuring LVEF.
Caliman, R.
2017-08-01
This paper contains an analysis of the factors that have an influence on the tribological characteristics of the composite material sintered with metal matrix reinforced with carbon fibers. These composites are used generally if it’s needed the wear resistant materials, whereas these composites have high specific strength in conjunction with a good corrosion resistance at low densities and some self-lubricating properties. Through the knowledge of the better tribological properties of the materials and their behavior to wear, can be generated by dry and the wet friction. Thus, where necessary the use of high temperature resistant material with low friction between the elements, carbon fiber composite materials are very suitable because they have: mechanical strength and good ductility, melting temperature on the higher values, higher electrical and thermal conductivity, lower wear speed and lower friction forces. For this purpose, this paper also contains an experimental program based on the evidence of formaldehyde resin made from fiber reinforced Cu-carbon with the aim to specifically determine the volume of fibers fraction for the consolidation of the composite material. In order to determine the friction coefficient and the wear rates of the various fiber reinforced polymer mixtures of carbon have been used special devices with needle-type with steel disc. These tests were conducted in the atmosphere at the room temperature without external lubrication study taking into consideration the sliding different speeds with constant loading task.
A framework of whole heart extracellular volume fraction estimation for low dose cardiac CT images
Chen, Xinjian; Summers, Ronald M.; Nacif, Marcelo Souto; Liu, Songtao; Bluemke, David A.; Yao, Jianhua
2012-02-01
Cardiac magnetic resonance imaging (CMRI) has been well validated and allows quantification of myocardial fibrosis in comparison to overall mass of the myocardium. Unfortunately, CMRI is relatively expensive and is contraindicated in patients with intracardiac devices. Cardiac CT (CCT) is widely available and has been validated for detection of scar and myocardial stress/rest perfusion. In this paper, we sought to evaluate the potential of low dose CCT for the measurement of myocardial whole heart extracellular volume (ECV) fraction. A novel framework was proposed for CCT whole heart ECV estimation, which consists of three main steps. First, a shape constrained graph cut (GC) method was proposed for myocardium and blood pool segmentation for post-contrast image. Second, the symmetric Demons deformable registrations method was applied to register pre-contrast to post-contrast images. Finally, the whole heart ECV value was computed. The proposed method was tested on 7 clinical low dose CCT datasets with pre-contrast and post-contrast images. The preliminary results demonstrated the feasibility and efficiency of the proposed method.
DEFF Research Database (Denmark)
Ghanbarpour, S.; Mazaheripour, H.; Mirmoradi, S. H.;
2010-01-01
is to investigate the effects of type and volume fraction of steel fiber on the compressive strength, split tensile strength, flexural strength and modulus of elasticity of steel fiber reinforced self-compacting concrete (SFRSCC). Design/methodology/approach – For this purpose, Micro wire and Wave type steel fibers...
Variable volume combustor with an air bypass system
Energy Technology Data Exchange (ETDEWEB)
Johnson, Thomas Edward; Ziminsky, Willy Steve; Ostebee, Heath Michael; Keener, Christopher Paul
2017-02-07
The present application provides a combustor for use with flow of fuel and a flow of air in a gas turbine engine. The combustor may include a number of micro-mixer fuel nozzles positioned within a liner and an air bypass system position about the liner. The air bypass system variably allows a bypass portion of the flow of air to bypass the micro-mixer fuel nozzles.
Del Bello, E.; Taddeucci, J.; De'Michieli Vitturi, M.; Scarlato, P.; Andronico, D.; Scollo, S.; Kueppers, U.
2015-12-01
We present the first report of experimental measurements of the enhanced settling velocity of volcanic particles as function of particle volume fraction. In order to investigate the differences in the aerodynamic behavior of ash particles when settling individually or in mass, we performed systematic large-scale ash settling experiments using natural basaltic and phonolitic ash. By releasing ash particles at different, controlled volumetric flow rates, in an unconstrained open space and at minimal air movement, we measured their terminal velocity, size, and particle volume fraction with a high-speed camera at 2000 fps. Enhanced settling velocities of individual particles increase with increasing particle volume fraction. This suggests that particle clustering during fallout may be one reason explaining larger than theoretical depletion rates of fine particles from volcanic ash clouds. We provide a quantitative empirical model that allows to calculate, from a given particle size and density, the enhanced velocity resulting from a given particle volume fraction. The proposed model has the potential to serve as a simple tool for the prediction of the terminal velocity of ash of an hypothetical distribution of ash of known particle size and volume fraction. This is of particular importance for advection-diffusion transport model of ash where generally a one-way coupling is adopted, considering only the flow effects on particles. To better quantify the importance of the enhanced settling velocity in ash dispersal, we finally introduced the new formulation in a Lagrangian model calculating for realistic eruptive conditions the resulting ash concentration in the atmosphere and on the ground.
Kailasanathan, Ranjith Kumar Abhinavam
2014-05-20
Soot surface temperature and volume fraction are measured in ethylene/air coflowing laminar diffusion flames at high pressures, diluted with one of four diluents (argon, helium, nitrogen, and carbon dioxide) using a two-color technique. Both temperature and soot measurements presented are line-of-sight averages. The results aid in understanding the kinetic and thermodynamic behavior of the soot formation and oxidation chemistry with changes in diluents, ultimately leading to possible methods of reducing soot emission from practical combustion hardware. The diluted fuel and coflow exit velocities (top-hat profiles) were matched at all pressures to minimize shear effects. In addition to the velocity-matched flow rates, the mass fluxes were held constant for all pressures. Addition of a diluent has a pronounced effect on both the soot surface temperature and volume fraction, with the helium diluted flame yielding the maximum and carbon dioxide diluted flame yielding minimum soot surface temperature and volume fraction. At low pressures, peak soot volume fraction exists at the tip of the flame, and with an increase in pressure, the location shifts lower to the wings of the flame. Due to the very high diffusivity of helium, significantly higher temperature and volume fraction are measured and explained. Carbon dioxide has the most dramatic soot suppression effect. By comparing the soot yield with previously measured soot precursor concentrations in the same flame, it is clear that the lower soot yield is a result of enhanced oxidation rates rather than a reduction in precursor formation. Copyright © 2014 Taylor & Francis Group, LLC.
Smirnov, A. S.; Belozerov, G. A.; Smirnova, E. O.; Konovalov, A. V.; Shveikin, V. P.; Muizemnek, O. Yu.
2016-07-01
The paper deals with a procedure of preparing a specimen surface for the EBSD analysis of a metal matrix composite (MMC) with a high volume fraction of reinforcing particles. Unlike standard procedures of preparing a specimen surface for the EBSD analysis, the proposed procedure is iterative with consecutive application of mechanical and electrochemical polishing. This procedure significantly improves the results of an indexed MMC matrix in comparison with the standard procedure of specimen preparation. The procedure was verified on a MMC with pure aluminum (99.8% Al) as the matrix, SiC particles being used as reinforcing elements. The average size of the SiC particles is 14 μm, and their volume fraction amounts to 50% of the total volume of the composite. It has been experimentally found that, for making the EBSD analysis of a material matrix near reinforcing particles, the difference in height between the particles and the matrix should not exceed 2 µm.
Bueno, Kelly; Adorne, Marcia D; Jornada, Denise S; da Fonseca, Francisco Noé; Guterres, Sílvia S; Pohlmann, Adriana R
2013-01-01
In nanomedicine, different nanomaterials and nanoparticles have been proposed as therapeutic agents or adjuvants, as well as diagnosis devices. Considering that the principal cause of the ulcerations is the imbalance among the gastric juice secretion and the protection provided by the mucosal barrier and the neutralization of the gastric acid, as well as that nanoparticles are able to accumulate in the gastro-intestinal tissues, we proposed a 2(2) factorial design to evaluate the influence of the chemical composition and the volume fraction of the dispersed phase on the gastric protective effect against ulceration induced by ethanol. Cocoa-theospheres (CT) and lipid-core nanocapsules (LNC) (two different kinds of surfaces: lipid and polymeric, respectively) prepared at two different concentrations of soft materials: 4% and 12% (w/v) were produced by high pressure homogenization and solvent displacement methods, respectively. Laser diffraction showed volume-weighted mean diameters ranging from 133 to 207 nm, number median diameters lower than 100 nm and specific surfaces between 41.2 and 51.2 m(2) g(-1). The formulations had pH ranging from 4.7 to 6.3; and zeta potential close to -9 mV due to their coating with polysorbate 80. The ulcer indexes were 0.40 (LNC(4)) and 0.48 (CT(4)) for the lower total administered areas (3.3 and 4.1 m(2)g(-1), respectively), and 0.09 (LNC(12) and CT(12)) for the higher administered areas (10.0 and 12.0 m(2) g(-1), respectively). LNC(4), LNC(12) and CT(12) showed lower levels in the lipid peroxidation assay when compared either to the negative control (saline) or to CT(4). LNC(12) and CT(12) showed similar TBARS levels, as well as CT(4) was similar to the negative control. SEM analysis of the stomach mucosa showed coatings more homogenous and cohesive when LNC formulations were administered compared to the correspondent CT formulations. The higher total area of administered nanoparticles showed film formation. Moreover, LNC(12
Extracellular volume fraction mapping in the myocardium, part 2: initial clinical experience
Directory of Open Access Journals (Sweden)
Kellman Peter
2012-09-01
Full Text Available Abstract Background Diffuse myocardial fibrosis, and to a lesser extent global myocardial edema, are important processes in heart disease which are difficult to assess or quantify with cardiovascular magnetic resonance (CMR using conventional late gadolinium enhancement (LGE or T1-mapping. Measurement of the myocardial extracellular volume fraction (ECV circumvents factors that confound T1-weighted images or T1-maps. We hypothesized that quantitative assessment of myocardial ECV would be clinically useful for detecting both focal and diffuse myocardial abnormalities in a variety of common and uncommon heart diseases. Methods A total of 156 subjects were imaged including 62 with normal findings, 33 patients with chronic myocardial infarction (MI, 33 with hypertrophic cardiomyopathy (HCM, 15 with non-ischemic dilated cardiomyopathy (DCM, 7 with acute myocarditis, 4 with cardiac amyloidosis, and 2 with systemic capillary leak syndrome (SCLS. Motion corrected ECV maps were generated automatically from T1-maps acquired pre- and post-contrast calibrated by blood hematocrit. Abnormally-elevated ECV was defined as >2SD from the mean ECV in individuals with normal findings. In HCM the size of regions of LGE was quantified as the region >2 SD from remote. Results Mean ECV of 62 normal individuals was 25.4 ± 2.5% (m ± SD, normal range 20.4%-30.4%. Mean ECV within the core of chronic myocardial infarctions (without MVO (N = 33 measured 68.5 ± 8.6% (p Conclusions ECV mapping appears promising to complement LGE imaging in cases of more homogenously diffuse disease. The ability to display ECV maps in units that are physiologically intuitive and may be interpreted on an absolute scale offers the potential for detection of diffuse disease and measurement of the extent and severity of abnormal regions.
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
A phase transformation model was presented for predicting the phase fraction transformed and the carbon concentration in austenite for austenite to ferrite transformation during laminar cooling on run-out table in hot rolling strip mill. In this model, the parameter k in Avrami equation was developed for carbon steels. The wide range of chemical composition, the primary austenite grain size, and the retained strain were taken into account. It can be used to predict the ferrite volume fraction and the carbon concentration in austenite of hot-rolled steel strip during laminar cooling on run-out table. The coiling temperature controlling model was also presented to calculate the temperature of steel strip. The transformation kinetics of austenite to ferrite and the evolution of carbon concentration in austenite at different temperatures during cooling were investigated in the hot rolled Q235B strip for thickness of 9.35, 6.4, and 3.2mm. The ferrite volume fraction along the length of the strip was also calculated. The calculated ferrite volume fraction was compared with the log data from hot strip mill and the calculated results were in agreement with the experimental ones. The present study is a part of the prediction of the mechanical properties of hot-rolled steel strip, and it has already been used on-line and off-line in the hot strip mill.
Directory of Open Access Journals (Sweden)
Weijie Yan
2017-05-01
Full Text Available A method for simultaneously visualizing the two-dimensional distributions of temperature and soot volume fraction in an ethylene flame was presented. A single-color charge-coupled device (CCD camera was used to capture the flame image in the visible spectrum considering the broad-response spectrum of the R and G bands of the camera. The directional emissive power of the R and G bands were calibrated and used for measurement. Slightly increased temperatures and reduced soot concentration were predicted in the central flame without self-absorption effects considered, an iterative algorithm was used for eliminating the effect of self-absorption. Nine different cases were presented in the experiment to demonstrate the effects of fuel mass flow rate and oxygen concentration on temperature and soot concentration in three different atmospheres. For ethylene combustion in pure-air atmosphere, as the fuel mass flow rate increased, the maximum temperature slightly decreased, and the maximum soot volume fraction slightly increased. For oxygen fractions of 30%, 40%, and 50% combustion in O2/N2 oxygen-enhanced atmospheres, the maximum flame temperatures were 2276, 2451, and 2678 K, whereas combustion in O2/CO2 atmospheres were 1916, 2322, and 2535 K. The maximum soot volume fractions were 4.5, 7.0, and 9.5 ppm in oxygen-enriched O2/N2 atmosphere and 13.6, 15.3, and 14.8 ppm in oxygen-enriched O2/CO2 atmosphere. Compared with the O2/CO2 atmosphere, combustion in the oxygen-enriched O2/N2 atmosphere produced higher flame temperature and larger soot volume fraction. Preliminary results indicated that this technique is reliable and can be used for combustion diagnosis.
Wang, Qiming; Yan, Xiaoqing; Ding, Shurong; Huo, Yongzhong
2010-05-01
A new method of modeling the in-pile mechanical behaviors of dispersion nuclear fuel elements is proposed. Considering the irradiation swelling together with the thermal effect, numerical simulations of the in-pile mechanical behaviors are performed with the developed finite element models for different fuel particle volume fractions of the fuel meat. The effects of the particle volume fractions on the mechanical performances of the fuel element are studied. The research results indicate that: (1) the maximum Mises stresses and equivalent plastic strains at the matrix increase with the particle volume fractions at each burnup; the locations of the maximum first principal stresses shift with increasing burnup; at low burnups, the maximum first principal stresses increase with the particle volume fractions; while at high burnups, the 20% volume fraction case holds the lowest value; (2) at the cladding, the maximum equivalent plastic strains and the tensile principal stresses increase with the particle volume fractions; while the maximum Mises stresses do not follow this order at high burnups; (3) the maximum Mises stresses at the fuel particles increase with the particle volume fractions, and the particles will engender plastic strains until the particle volume fraction reaches high enough.
DEFF Research Database (Denmark)
Oddershede, Jette; Majkut, Marta; Caosyd, Qinghua
2015-01-01
A method for the extension of the three-dimensional X-ray diffraction technique to allow the extraction of domain volume fractions in polycrystalline ferroic materials is presented. This method gives access to quantitative domain volume fractions of hundreds of independent embedded grains within...
Nazarian, Ara; von Stechow, Dietrich; Zurakowski, David; Müller, Ralph; Snyder, Brian D
2008-12-01
Preventing nontraumatic fractures in millions of patients with osteoporosis or metastatic cancer may significantly reduce the associated morbidity and reduce health-care expenditures incurred by these fractures. Predicting fracture occurrence requires an accurate understanding of the relationship between bone structure and the mechanical properties governing bone fracture that can be readily measured. The aim of this study was to test the hypothesis that a single analytic relationship with either bone tissue mineral density or bone volume fraction (BV/TV) as independent variables could predict the strength and stiffness of normal and pathologic cancellous bone affected by osteoporosis or metastatic cancer. After obtaining institutional review board approval and informed consent, 15 patients underwent excisional biopsy of metastatic prostate, breast, lung, ovarian, or colon cancer from the spine and/or femur to obtain 41 metastatic cancer specimens. In addition, 96 noncancer specimens were excised from 43 age- and site-matched cadavers. All specimens were imaged using micro-computed tomography (micro-CT) and backscatter emission imaging and tested mechanically by uniaxial compression and nanoindentation. The minimum BV/TV, measured using quantitative micro-CT, accounted for 84% of the variation in bone stiffness and strength for all cancellous bone specimens. While relationships relating bone density to strength and stiffness have been derived empirically for normal and osteoporotic bone, these relationships have not been applied to skeletal metastases. This simple analytic relationship will facilitate large-scale screening and prediction of fracture risk for normal and pathologic cancellous bone using clinical CT systems to determine the load capacity of bones altered by metastatic cancer, osteoporosis, or both.
Energy Technology Data Exchange (ETDEWEB)
Lundqvist, Eva; Segelsjoe, Monica; Magnusson, Anders [Uppsala Univ., Dept. of Radiology, Oncology and Radiation Science, Section of Radiology, Uppsala (Sweden)], E-mail: eva.lundqvist.8954@student.uu.se; Andersson, Anna; Biglarnia, Ali-Reza [Dept. of Surgical Sciences, Section of Transplantation Surgery, Uppsala Univ. Hospital, Uppsala (Sweden)
2012-11-15
Background Unlike other solid organ transplants, pancreas allografts can undergo a substantial decrease in baseline volume after transplantation. This phenomenon has not been well characterized, as there are insufficient data on reliable and reproducible volume assessments. We hypothesized that characterization of pancreatic volume by means of computed tomography (CT) could be a useful method for clinical follow-up in pancreas transplant patients. Purpose To evaluate the feasibility and reliability of pancreatic volume assessment using CT scan in transplanted patients. Material and Methods CT examinations were performed on 21 consecutive patients undergoing pancreas transplantation. Volume measurements were carried out by two observers tracing the pancreatic contours in all slices. The observers performed the measurements twice for each patient. Differences in volume measurement were used to evaluate intra- and inter-observer variability. Results The intra-observer variability for the pancreatic volume measurements of Observers 1 and 2 was found to be in almost perfect agreement, with an intraclass correlation coefficient (ICC) of 0.90 (0.77-0.96) and 0.99 (0.98-1.0), respectively. Regarding inter-observer validity, the ICCs for the first and second measurements were 0.90 (range, 0.77-0.96) and 0.95 (range, 0.85-0.98), respectively. Conclusion CT volumetry is a reliable and reproducible method for measurement of transplanted pancreatic volume.
Energy Technology Data Exchange (ETDEWEB)
Raebiger, K. [LEISTRITZ Pumpen GmbH, Nuremberg (Germany); Faculty of Advanced Technology, University of Glamorgan, Pontypridd, Wales (United Kingdom); Maksoud, T.M.A.; Ward, J. [Faculty of Advanced Technology, University of Glamorgan, Pontypridd, Wales (United Kingdom); Hausmann, G. [Department of Mechanical Engineering and Building Services Engineering, University of Applied Sciences, Nuremberg (Germany)
2008-09-15
In the investigation of the pumping behaviour of multiphase screw pumps, handling gas-liquid mixtures with very high gas volume fractions, theoretical and experimental analyses were performed. A new theoretical screw pump model was developed, which calculates the time-dependent conditions inside the several chambers of a screw pump as well as the exchange of mass and energy between these chambers. By means of the performed experimental analysis, the screw pump model was verified, especially at very high gas volume fractions from 90% to 99%. The experiments, which were conducted with the reference fluids water and air, can be divided mainly into the determination of the steady state pumping behaviour on the one hand and into the analysis of selected transient operating conditions on the other hand, whereas the visualisation of the leakage flows through the circumferential gaps was rounded off the experimental analysis. (author)
Directory of Open Access Journals (Sweden)
Hong-Meng Li
2014-07-01
Full Text Available An experimental study of the intrinsic instabilities of H2/CO lean (φ = 0.4 to φ = 1.0 premixed flames at different hydrogen fractions ranging from 0% to 100% at elevated pressure and room temperature was performed in a constant volume vessel using a Schlieren system. The unstretched laminar burning velocities were compared with data from the previous literature and simulated results. The results indicate that excellent agreements are obtained. The cellular instabilities of syngas-air flames were discussed and critical flame radii were measured. When hydrogen fractions are above 50%, the flame tends to be more stable as the equivalence ratio increases; however, the instability increases for flames of lower hydrogen fractions. For the premixed syngas flame with hydrogen fractions greater than 50%, the decline in cellular instabilities induced by the increase in equivalence ratio can be attributed to a reduction of diffusive-thermal instabilities rather than increased hydrodynamic instabilities. For premixed syngas flames with hydrogen fractions lower than 50%, as the equivalence ratio increases, the cellular instabilities become more evident because the enhanced hydrodynamic instabilities become the dominant effect. For premixed syngas flames, the enhancement of cellular instabilities induced by the increase in hydrogen fraction is the result of both increasing diffusive-thermal and hydrodynamic instabilities.
Bevill, Grant; Eswaran, Senthil K; Gupta, Atul; Papadopoulos, Panayiotis; Keaveny, Tony M
2006-12-01
Large-deformation bending and buckling have long been proposed as failure mechanisms by which the strength of trabecular bone can be affected disproportionately to changes in bone density, and thus may represent an important aspect of bone quality. We sought here to quantify the contribution of large-deformation failure mechanisms on strength, to determine the dependence of these effects on bone volume fraction and architecture, and to confirm that the inclusion of large-deformation effects in high-resolution finite element models improves predictions of strength versus experiment. Micro-CT-based finite element models having uniform hard tissue material properties were created from 54 cores of human trabecular bone taken from four anatomic sites (age = 70+/-11; 24 male, 27 female donors), which were subsequently biomechanically tested to failure. Strength predictions were made from the models first including, then excluding, large-deformation failure mechanisms, both for compressive and tensile load cases. As expected, strength predictions versus experimental data for the large-deformation finite element models were significantly improved (p deformation models in both tension and compression. Below a volume fraction of about 0.20, large-deformation failure mechanisms decreased trabecular strength from 5-80% for compressive loading, while effects were negligible above this volume fraction. Step-wise nonlinear multiple regression revealed that structure model index (SMI) and volume fraction (BV/TV) were significant predictors of these reductions in strength (R2 = 0.83, p deformation failure mechanisms on trabecular bone strength is highly heterogeneous and is not well explained by standard architectural metrics.
Sledkov, R. M.; Galkin, I. Yu.; Stepanov, O. E.; Strebnev, N. A.
2017-01-01
When one solves engineering problems related to the cooling of fuel assemblies (FAs) in a spent fuel storage pool (SFSP) and the assessment of nuclear safety of FA storage in an SFSP in the initial event of loss of SFSP cooling, it is essential to determine the coolant density and, consequently, steam volume fractions φ in bundles of fuel elements at a pressure of 0.1-0.5 MPa. Such formulas for calculating φ that remain valid in a wide range of operating parameters and geometric shapes of channels and take the conditions of loss of SFSP cooling into account are currently almost lacking. The results of systematization and analysis of the available formulas for φ are reported in the present study. The calculated values were compared with the experimental data obtained in the process of simulating the conditions of FA cooling in an SFSP in the event of loss of its cooling. Six formulas for calculating the steam volume fraction, which were used in this comparison, were chosen from a total of 11 considered relations. As a result, the formulas producing the most accurate values of φ in the conditions of loss of SFSP cooling were selected. In addition, a relation that allows one to perform more accurate calculations of steam volume fractions in the conditions of loss of SFSP cooling was derived based on the Fedorov formula in the two-group approximation.
Laufer, N.; Hansmann, H.; Koch, M.
2017-01-01
In this study, the rheological properties of wood plastic composites (WPC) with different polymeric matrices (LDPE, low-density polyethylene and PP, polypropylene) and with different types of wood filler (hardwood flour and softwood flour) have been investigated by means of high pressure capillary rheometry. The volume fraction of wood was varied between 0 and 60 %. The shear thinning behaviour of the WPC melts can be well described by the Ostwald - de Waele power law relationship. The flow consistency index K of the power law shows a good correlation with the volume fraction of wood. Interparticular interaction effects of wood particles can be mathematically taken into account by implementation of an interaction exponent (defined as the ratio between flow exponent of WPC and flow exponent of polymeric matrix). The interaction exponent shows a good correlation with the flow consistency index. On the basis of these relationships the concept of shear-stress-equivalent inner shear rate has been modified. Thus, the flow behaviour of the investigated wood filled polymer melts could be well described mathematically by the modified concept of shear-stress-equivalent inner shear rate. On this basis, the shear thinning behaviour of WPC can now be estimated with good accuracy, taking into account the volume fraction of wood.
Gilder, Michael; Ramsbottom, Roger
2008-12-05
Physically active individuals demonstrate increased heart rate variability (HRV) during rest compared to sedentary individuals, but the impact of different volumes of regular exercise on the HRV response to postural change is not well understood. This study investigates change in HRV following orthostasis in seventy-two young women who exercise at low (LV) or high (HV) volumes of physical activity. Supine and standing R-R intervals were analysed by time domain, frequency domain and Poincaré plot methods. All methods revealed greater change in the vagal response in the HV group, indicating that HRV following postural change is modulated by volume of exercise.
Podlubny, Igor; Skovranek, Tomas; Vinagre Jara, Blas M; Petras, Ivo; Verbitsky, Viktor; Chen, YangQuan
2013-05-13
In this paper, we further develop Podlubny's matrix approach to discretization of integrals and derivatives of non-integer order. Numerical integration and differentiation on non-equidistant grids is introduced and illustrated by several examples of numerical solution of differential equations with fractional derivatives of constant orders and with distributed-order derivatives. In this paper, for the first time, we present a variable-step-length approach that we call 'the method of large steps', because it is applied in combination with the matrix approach for each 'large step'. This new method is also illustrated by an easy-to-follow example. The presented approach allows fractional-order and distributed-order differentiation and integration of non-uniformly sampled signals, and opens the way to development of variable- and adaptive-step-length techniques for fractional- and distributed-order differential equations.
Henriques, Isabela; Padilha, Gisele A; Huhle, Robert; Wierzchon, Caio; Miranda, Paulo J B; Ramos, Isalira P; Rocha, Nazareth; Cruz, Fernanda F; Santos, Raquel S; de Oliveira, Milena V; Souza, Sergio A; Goldenberg, Regina C; Luiz, Ronir R; Pelosi, Paolo; de Abreu, Marcelo G; Silva, Pedro L; Rocco, Patricia R M
2016-01-01
Emphysema is characterized by loss of lung tissue elasticity and destruction of structures supporting alveoli and capillaries. The impact of mechanical ventilation strategies on ventilator-induced lung injury (VILI) in emphysema is poorly defined. New ventilator strategies should be developed to minimize VILI in emphysema. The present study was divided into two protocols: (1) characterization of an elastase-induced emphysema model in rats and identification of the time point of greatest cardiorespiratory impairment, defined as a high specific lung elastance associated with large right ventricular end-diastolic area; and (2) comparison between variable (VV) and conventional volume-controlled ventilation (VCV) on lung mechanics and morphometry, biological markers, and cardiac function at that time point. In the first protocol, Wistar rats (n = 62) received saline (SAL) or porcine pancreatic elastase (ELA) intratracheally once weekly for 4 weeks, respectively. Evaluations were performed 1, 3, 5, or 8 weeks after the last intratracheal instillation of saline or elastase. After identifying the time point of greatest cardiorespiratory impairment, an additional 32 Wistar rats were randomized into the SAL and ELA groups and then ventilated with VV or VCV (n = 8/group) [tidal volume (VT) = 6 mL/kg, positive end-expiratory pressure (PEEP) = 3 cmH2O, fraction of inspired oxygen (FiO2) = 0.4] for 2 h. VV was applied on a breath-to-breath basis as a sequence of randomly generated VT values (mean VT = 6 mL/kg), with a 30% coefficient of variation. Non-ventilated (NV) SAL and ELA animals were used for molecular biology analysis. The time point of greatest cardiorespiratory impairment, was observed 5 weeks after the last elastase instillation. At this time point, interleukin (IL)-6, cytokine-induced neutrophil chemoattractant (CINC)-1, amphiregulin, angiopoietin (Ang)-2, and vascular endothelial growth factor (VEGF) mRNA levels were higher in ELA compared to SAL. In ELA animals
Henriques, Isabela; Padilha, Gisele A.; Huhle, Robert; Wierzchon, Caio; Miranda, Paulo J. B.; Ramos, Isalira P.; Rocha, Nazareth; Cruz, Fernanda F.; Santos, Raquel S.; de Oliveira, Milena V.; Souza, Sergio A.; Goldenberg, Regina C.; Luiz, Ronir R.; Pelosi, Paolo; de Abreu, Marcelo G.; Silva, Pedro L.; Rocco, Patricia R. M.
2016-01-01
Emphysema is characterized by loss of lung tissue elasticity and destruction of structures supporting alveoli and capillaries. The impact of mechanical ventilation strategies on ventilator-induced lung injury (VILI) in emphysema is poorly defined. New ventilator strategies should be developed to minimize VILI in emphysema. The present study was divided into two protocols: (1) characterization of an elastase-induced emphysema model in rats and identification of the time point of greatest cardiorespiratory impairment, defined as a high specific lung elastance associated with large right ventricular end-diastolic area; and (2) comparison between variable (VV) and conventional volume-controlled ventilation (VCV) on lung mechanics and morphometry, biological markers, and cardiac function at that time point. In the first protocol, Wistar rats (n = 62) received saline (SAL) or porcine pancreatic elastase (ELA) intratracheally once weekly for 4 weeks, respectively. Evaluations were performed 1, 3, 5, or 8 weeks after the last intratracheal instillation of saline or elastase. After identifying the time point of greatest cardiorespiratory impairment, an additional 32 Wistar rats were randomized into the SAL and ELA groups and then ventilated with VV or VCV (n = 8/group) [tidal volume (VT) = 6 mL/kg, positive end-expiratory pressure (PEEP) = 3 cmH2O, fraction of inspired oxygen (FiO2) = 0.4] for 2 h. VV was applied on a breath-to-breath basis as a sequence of randomly generated VT values (mean VT = 6 mL/kg), with a 30% coefficient of variation. Non-ventilated (NV) SAL and ELA animals were used for molecular biology analysis. The time point of greatest cardiorespiratory impairment, was observed 5 weeks after the last elastase instillation. At this time point, interleukin (IL)-6, cytokine-induced neutrophil chemoattractant (CINC)-1, amphiregulin, angiopoietin (Ang)-2, and vascular endothelial growth factor (VEGF) mRNA levels were higher in ELA compared to SAL. In ELA animals
Kinoshita, Y; Nanbu, I; Tohyama, J; Ooba, S
1998-02-01
We evaluated accuracy of Quantitative Gated SPECT Program that enabled calculation of the left ventricular (LV) volume and ejection fraction by automatically tracing the contour of the cardiac surface. Cardiac phantoms filled with 99mTc-solution were used. Data acquisition was made by 180-degree projection in L type and 360-degree projection in opposed type. Automatic calculation could be done in all processes, which required 3-4 minutes. Reproducibility was sufficient. The adequate cut off value of a prefilter was 0.45. At this value LV volume was 93% of the actual volume in L type acquisition and 95.9% in opposed type acquisition. The LV volume obtained in L type was smaller than that obtained in opposed type (p defects was fair, on the cardiac phantoms with all of 90-degree defects and 180-degree defects of the septal and lateral wall. The LV volume was estimated to be larger on the phantom with 180-degree defect of the anterior wall, and to be smaller on the phantom of 180-degree defect of the inferoposterior wall. Because tracing was deviated anteriorly at the defects. In the patients with similar conditions to 180-degree defect of the anterior wall or inferoposterior wall, the LV volume should be carefully evaluated.
Energy Technology Data Exchange (ETDEWEB)
Kinoshita, Yoshimi; Nanbu, Ichirou [Nagoya Daini Red Cross Hospital (Japan); Tohyama, Junko; Ooba, Satoru
1998-02-01
We evaluated accuracy of Quantitative Gated SPECT Program that enabled calculation of the left ventricular (LV) volume and ejection fraction by automatically tracing the contour of the cardiac surface. Cardiac phantoms filled with {sup 99m}Tc-solution were used. Data acquisition was made by 180-degree projection in L type and 360-degree projection in opposed type. Automatic calculation could be done in all processes, which required 3-4 minutes. Reproducibility was sufficient. The adequate cut off value of a prefilter was 0.45. At this value LV volume was 93% of the actual volume in L type acquisition and 95.9% in opposed type acquisition. The LV volume obtained in L type was smaller than that obtained in opposed type (p<0.05). The tracing of the defects was fair, on the cardiac phantoms with all of 90-degree defects and 180-degree defects of the septal and lateral wall. The LV volume was estimated to be larger on the phantom with 180-degree defect of the anterior wall, and to be smaller on the phantom of 180-degree defect of the inferoposterior wall. Because tracing was deviated anteriorly at the defects. In the patients with similar conditions to 180-degree defect of the anterior wall or inferoposterior wall, the LV volume should be carefully evaluated. (author)
Directory of Open Access Journals (Sweden)
Piotr Kubica
2015-01-01
Full Text Available The transport properties of the poly(ethylene-co-vinyl acetate (EVA materials to He, N2, O2, and CO2 are correlated with two polymer molecular structure parameters, that is, cohesive energy density (CED and fractional free volume (FFV, determined by the group contribution method. In our preceding paper, the attempt was made to approximate EVA permeability using a linear function of 1/FFV as predicted by the free volume theory. However, the deviations from this relationship appeared to be significant. In this paper, it is shown that permeation of gas molecules is controlled not only by free volume but also by the polymer cohesive energy. Moreover, the behavior of CO2 was found to differ significantly from that of other gases. In this instance, the correlation is much better when diffusivity instead of permeability is taken into account in a modified transport model.
Energy Technology Data Exchange (ETDEWEB)
Sudhoff, M; Lamba, M; Kumar, N; Ward, A; Elson, H [University of Cincinnati, Cincinnati, OH (United States)
2015-06-15
Purpose: To systematically characterize inter-fraction breast variability and determine implications on delivered dose. Methods: Weekly port films were used to characterize breast setup variability. Five evenly spaced representative positions across the contour of each breast were chosen on the electronic port film in reference to graticule, and window and level was set such that the skin surface of the breast was visible. Measurements from the skin surface to treatment field edge were taken on each port film at each position and compared to the planning DRR, quantifying the variability. The systematic measurement technique was repeated for all port films for 20 recently treated breast cancer patients. Measured setup variability for each patient was modeled as a normal distribution. The distribution was randomly sampled from the model and applied as isocentric shifts in the treatment planning computer, representing setup variability for each fraction. Dose was calculated for each shifted fraction and summed to obtain DVHs and BEDs that modeled the dose with daily setup variability. Patients were categorized in to relevant groupings that were chosen to investigate the rigorousness of immobilization types, treatment techniques, and inherent anatomical difficulties. Mean position differences and dosimetric differences were evaluated between planned and delivered doses. Results: The setup variability was found to follow a normal distribution with mean position differences between the DRR and port film between − 8.6–3.5 mm with sigma range of 5.3–9.8 mm. Setup position was not found to be significantly different than zero. The mean seroma or whole breast PTV dosimetric difference, calculated as BED, ranged from a −0.23 to +1.13Gy. Conclusion: A systematic technique to quantify and model setup variability was used to calculate the dose in 20 breast cancer patients including variable setup. No statistically significant PTV or OAR BED differences were found between
Indian Academy of Sciences (India)
M Matinfar; M Eslami; M Kordy
2015-10-01
This paper presents the exact solutions for the fractional Korteweg–de Vries equations and the coupled Korteweg–de Vries equations with time-fractional derivatives using the functional variable method. The fractional derivatives are described in the modified Riemann–Liouville derivative sense. It is demonstrated that the calculations involved in the functional variable method are extremely simple and straightforward and this method is very effective for handling nonlinear fractional equations.
Energy Technology Data Exchange (ETDEWEB)
Faroughi, Salah Aldin, E-mail: salah-faroughi@gatech.edu [School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta 30332-0340 (United States); Huber, Christian [School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta 30332-0340 (United States)
2015-02-07
In this study, we propose a theoretical model to compute the effective thermal conductivity of metal and dielectric spherical particle reinforced composites with interfacial thermal resistance. We consider a wide range of filler volume fraction with sizes ranging from nano- to macro-scale. The model, based on the differential effective medium theory, accounts for particle interactions through two sets of volume fraction corrections. The first correction accounts for a finite volume of composite and the second correction introduces a self-crowding factor that allows us to develop an accurate model for particle interaction even for high volume fraction of fillers. The model is examined to other published models, experiments, and numerical simulations for different types of composites. We observe an excellent agreement between the model and published datasets over a wide range of particle volume fractions and material properties of the composite constituents.
Energy Technology Data Exchange (ETDEWEB)
Sugano, Yasutaka [Graduate School of Health Sciences, Hokkaido University, Kita-12, Nishi-5, Kita-ku, Sapporo, Hokkaido 060-0812 (Japan); Mizuta, Masahiro [Laboratory of Advanced Data Science, Information Initiative Center, Hokkaido University, Kita-11, Nishi-5, Kita-ku, Sapporo, Hokkaido 060-0811 (Japan); Takao, Seishin; Shirato, Hiroki; Sutherland, Kenneth L. [Department of Radiation Medicine, Graduate School of Medicine, Hokkaido University, Kita-15, Nishi-5, Kita-ku, Sapporo, Hokkaido 060-8638 (Japan); Date, Hiroyuki, E-mail: date@hs.hokudai.ac.jp [Faculty of Health Sciences, Hokkaido University, Kita-12, Nishi-5, Kita-ku, Sapporo, Hokkaido 060-0812 (Japan)
2015-11-15
Purpose: Radiotherapy of solid tumors has been performed with various fractionation regimens such as multi- and hypofractionations. However, the ability to optimize the fractionation regimen considering the physical dose distribution remains insufficient. This study aims to optimize the fractionation regimen, in which the authors propose a graphical method for selecting the optimal number of fractions (n) and dose per fraction (d) based on dose–volume histograms for tumor and normal tissues of organs around the tumor. Methods: Modified linear-quadratic models were employed to estimate the radiation effects on the tumor and an organ at risk (OAR), where the repopulation of the tumor cells and the linearity of the dose-response curve in the high dose range of the surviving fraction were considered. The minimization problem for the damage effect on the OAR was solved under the constraint that the radiation effect on the tumor is fixed by a graphical method. Here, the damage effect on the OAR was estimated based on the dose–volume histogram. Results: It was found that the optimization of fractionation scheme incorporating the dose–volume histogram is possible by employing appropriate cell surviving models. The graphical method considering the repopulation of tumor cells and a rectilinear response in the high dose range enables them to derive the optimal number of fractions and dose per fraction. For example, in the treatment of prostate cancer, the optimal fractionation was suggested to lie in the range of 8–32 fractions with a daily dose of 2.2–6.3 Gy. Conclusions: It is possible to optimize the number of fractions and dose per fraction based on the physical dose distribution (i.e., dose–volume histogram) by the graphical method considering the effects on tumor and OARs around the tumor. This method may stipulate a new guideline to optimize the fractionation regimen for physics-guided fractionation.
Miller, W. S.
1974-01-01
The cryogenic refrigerator thermal design calculations establish design approach and basic sizing of the machine's elements. After the basic design is defined, effort concentrates on matching the thermodynamic design with that of the heat transfer devices (heat exchangers and regenerators). Typically, the heat transfer device configurations and volumes are adjusted to improve their heat transfer and pressure drop characteristics. These adjustments imply that changes be made to the active displaced volumes, compensating for the influence of the heat transfer devices on the thermodynamic processes of the working fluid. Then, once the active volumes are changed, the heat transfer devices require adjustment to account for the variations in flows, pressure levels, and heat loads. This iterative process is continued until the thermodynamic cycle parameters match the design of the heat transfer devices. By examing several matched designs, a near-optimum refrigerator is selected.
Nguyen, B. V.; Challagulla, K. S.; Venkatesh, T. A.; Hadjiloizi, D. A.; Georgiades, A. V.
2016-12-01
Unit-cell based finite element models are developed to completely characterize the role of porosity distribution and porosity volume fraction in determining the elastic, dielectric and piezoelectric properties as well as relevant figures of merit of 3-3 type piezoelectric foam structures. Eight classes of foam structures which represent structures with different types and degrees of uniformity of porosity distribution are identified; a Base structure (Class I), two H-type foam structures (Classes II, and III), a Cross-type foam structure (Class IV) and four Line-type foam structures (Classes V, VI, VII, and VIII). Three geometric factors that influence the electromechanical properties are identified: (i) the number of pores per face, pore size and the distance between the pores; (ii) pore orientation with respect to poling direction; (iii) the overall symmetry of the pore distribution with respect to the center of the face of the unit cell. To assess the suitability of these structures for such applications as hydrophones, bone implants, medical imaging and diagnostic devices, five figures of merit are determined via the developed finite element model; the piezoelectric coupling constant (K t ), the acoustic impedance (Z), the piezoelectric charge coefficient (d h ), the hydrostatic voltage coefficient (g h ), and the hydrostatic figure of merit (d h g h ). At high material volume fractions, foams with non-uniform Line-type porosity (Classes V and VII) where the pores are preferentially distributed perpendicular to poling direction, are found to exhibit the best combination of desirable piezoelectric figures of merit. For example, at about 50% volume fraction, the d h , g h , and d h g h figures of merit are 55%, 1600% and 2500% higher, respectively, for Classes V and VII of Line-like foam structures compared with the Base structure.
Bahşı, Ayşe Kurt; Yalçınbaş, Salih
2016-01-01
In this study, the Fibonacci collocation method based on the Fibonacci polynomials are presented to solve for the fractional diffusion equations with variable coefficients. The fractional derivatives are described in the Caputo sense. This method is derived by expanding the approximate solution with Fibonacci polynomials. Using this method of the fractional derivative this equation can be reduced to a set of linear algebraic equations. Also, an error estimation algorithm which is based on the residual functions is presented for this method. The approximate solutions are improved by using this error estimation algorithm. If the exact solution of the problem is not known, the absolute error function of the problems can be approximately computed by using the Fibonacci polynomial solution. By using this error estimation function, we can find improved solutions which are more efficient than direct numerical solutions. Numerical examples, figures, tables are comparisons have been presented to show efficiency and usable of proposed method.
Energy Technology Data Exchange (ETDEWEB)
Jeong, K.; Choo, Y. S.; Hong, H. J.; Yoon, Y. S.; Song, M. H., E-mail: songm@dgu.edu [Department of Mechanical, Robotics, and Energy Engineering, Dongguk University, Seoul 100-715 (Korea, Republic of)
2015-03-15
Vast size hydrate formation reactors with fast conversion rate are required for the economic implementation of seawater desalination utilizing gas hydrate technology. The commercial target production rate is order of thousand tons of potable water per day per train. Various heat and mass transfer enhancement schemes including agitation, spraying, and bubbling have been examined to maximize the production capacities in scaled up design of hydrate formation reactors. The present experimental study focused on acquiring basic knowledge needed to design variable volume reactors to produce tetrafluoroethane hydrate slurry. Test vessel was composed of main cavity with fixed volume of 140 ml and auxiliary cavity with variable volume of 0 ∼ 64 ml. Temperatures at multiple locations within vessel and pressure were monitored while visual access was made through front window. Alternating evaporation and condensation induced by cyclic volume change provided agitation due to density differences among water and vapor, liquid and hydrate R134a as well as extended interface area, which improved hydrate formation kinetics coupled with latent heat release and absorption. Influences of coolant temperature, piston stroke/speed, and volume change period on hydrate formation kinetics were investigated. Suggestions of reactor design improvement for future experimental study are also made.
Energy Technology Data Exchange (ETDEWEB)
Johnson, J.
1995-12-31
A preliminary study of a new method for determining respirable mass concentration is described. This method uses a high volume air sampler and subsequent fractionation of the collected mass using a particle sedimentation technique. Side-by-side comparisons of this method with cyclones were made in the field and in the laboratory. There was good agreement among the samplers in the laboratory, but poor agreement in the field. The effect of wind on the samplers` capture efficiencies is the primary hypothesized source of error among the field results. The field test took place at the construction site of a hazardous waste landfill located on the Hanford Reservation.
Energy Technology Data Exchange (ETDEWEB)
Devaraj, Arun [Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL); Prabhakaran, Ramprashad [Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL); Joshi, Vineet V. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL); Hu, Shenyang Y. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL); McGarrah, Eric J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL); Lavender, Curt A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL)
2016-04-12
The purpose of this document is to provide a theoretical framework for (1) estimating uranium carbide (UC) volume fraction in a final alloy of uranium with 10 weight percent molybdenum (U 10Mo) as a function of final alloy carbon concentration, and (2) estimating effective 235U enrichment in the U 10Mo matrix after accounting for loss of 235U in forming UC. This report will also serve as a theoretical baseline for effective density of as-cast low-enriched U 10Mo alloy. Therefore, this report will serve as the baseline for quality control of final alloy carbon content
Al-Marahleh, G.
2006-05-01
The structure and properties of an aluminum alloy after extrusion in cast and homogenized states are studied. Commercial billets are melted in a horizontal continuous casting installation. After homogenizing the billets are used for fabricating shapes of specified form in an extrusion press. The shapes are subjected to final aging. The volume fraction and the distribution of the second Mg2Si phase are determined after different kinds of treatment. The structure and mechanical properties of shapes obtained from cast and homogenized billets are compared after aging and without aging. The effect of homogenizing on the properties of the alloy after extrusion is analyzed.
DEFF Research Database (Denmark)
Kelbaek, H; Svendsen, Jesper Hastrup; Aldershvile, J;
2011-01-01
The stroke volume (SV) was determined by first passage radionuclide cardiography and the left ventricular ejection fraction (LVEF) by multigated radionuclide cardiography in 20 patients with ischemic heart disease. The results were evaluated against those obtained by the invasive dye dilution...... or thermodilution and left ventricular cardioangiographic techniques. In a paired comparison the mean difference between the invasive and radionuclide SV was -1 ml (SED 3.1) with a correlation coefficient of 0.83 (p less than 0.01). Radionuclide LVEF values also correlated well with cardioangiographic measurements...
Directory of Open Access Journals (Sweden)
I. Didenkulova
2010-11-01
Full Text Available Tsunami wave generation by submarine landslides of a variable volume in a basin of variable depth is studied within the shallow-water theory. The problem of landslide induced tsunami wave generation and propagation is studied analytically for two specific convex bottom profiles (h ~ x^{4/3} and h ~ x^{4}. In these cases the basic equations can be reduced to the constant-coefficient wave equation with the forcing determined by the landslide motion. For certain conditions on the landslide characteristics (speed and volume per unit cross-section the wave field can be described explicitly. It is represented by one forced wave propagating with the speed of the landslide and following its offshore direction, and two free waves propagating in opposite directions with the wave celerity. For the case of a near-resonant motion of the landslide along the power bottom profile h ~ x^{γ} the dynamics of the waves propagating offshore is studied using the asymptotic approach. If the landslide is moving in the fully resonant regime the explicit formula for the amplitude of the wave can be derived. It is demonstrated that generally tsunami wave amplitude varies non-monotonically with distance.
Spatial variability of theaflavins and thearubigins fractions and their impact on black tea quality.
Bhuyan, Lakshi Prasad; Borah, Paban; Sabhapondit, Santanu; Gogoi, Ramen; Bhattacharyya, Pradip
2015-12-01
The spatial distribution of theaflavin and thearubigin fractions and their impact on black tea quality were investigated using multivariate and geostatistics techniques. Black tea samples were collected from tea gardens of six geographical regions of Assam and West Bengal, India. Total theaflavin (TF) and its four fractions of upper Assam, south bank and North Bank teas were higher than the other regions. Simple theaflavin showed highest significant correlation with tasters' quality. Low molecular weight thearubigins of south bank and North Bank were significantly higher than other regions. Total thearubigin (TR) and its fractions revealed significant positive correlation with tasters' organoleptic valuations. Tea tasters' parameters were significantly and positively correlated with each other. The semivariogram for quality parameters were best represented by gaussian models. The nugget/sill ratio indicated a strong/moderate spatial dependence of the studied parameters. Spatial variation of tea quality parameters may be used for quality assessment in the tea growing areas of India.
Leavitt, W.; Bradley, A. S.; Johnston, D. T.; Pereira, I. A. C.; Venceslau, S.; Wallace, C.
2014-12-01
Microbial sulfate reducers (MSR) drive the Earth's biogeochemical sulfur cycle. At the heart of this energy metabolism is a cascade of redox transformations coupling organic carbon and/or hydrogen oxidation to the dissimilatory reduction of sulfate to sulfide. The sulfide produced is depleted in the heavier isotopes of sulfur relative to sulfate. The magnitude of discrimination (fractionation) depends on: i) the cell-specific sulfate reduction rate (csSRR, Kaplan & Rittenberg (1964) Can. J. Microbio.; Chambers et al. (1975) Can. J. Microbio; Sim et al. (2011) GCA; Leavitt et al. (2013) PNAS), ii) the ambient sulfate concentration (Harrison & Thode (1958) Research; Habicht et al. (2002) Science; Bradley et al. in review), iii) both sulfate and electron donor availability, or iv) an intrinsic physiological limitation (e.g. cellular division rate). When neither sulfate nor electron donor limits csSRR a more complex function relates the magnitude of isotope fractionation to cell physiology and environmental conditions. In recent and on-going work we have examined the importance of enzyme-specific fractionation factors, as well as the influence of electron donor or electron acceptor availability under carefully controlled culture conditions (e.g. Leavitt et al. (2013) PNAS). In light of recent advances in MSR genetics and biochemistry we utilize well-characterized mutant strains, along with a continuous-culture methodology (Leavitt et al. (2013) PNAS) to further probe the fractionation capacity of this metabolism under controlled physiological conditions. We present our latest findings on the magnitude of S and D/H isotope fractionation in both wild type and mutant strains. We will discuss these in light of recent theoretical advances (Wing & Halevy (2014) PNAS), examining the mode and relevance of MSR isotope fractionation in the laboratory to modern and ancient environmental settings, particularly anoxic marine sediments.
FRACTIONAL INTEGRALS WITH VARIABLE KERNELS ON HARDY SPACES%变量核分数次积分在Hardy空间的有界性
Institute of Scientific and Technical Information of China (English)
张璞; 丁勇
2003-01-01
The fractional integral operators with variable kernels are discussed.It is proved that if the kernel satisfies the Dini-condition,then the fractional integral operators with variable kernels are bounded from ≤1 and 1/ q =1/ p-α/n .The results in this paper improve the results obtained by Ding,Chen and Fan in 2002.
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Guo-yuan Sun
2015-05-01
Full Text Available A dendritic β-phase reinforced bulk metallic glass (BMG composite named as D2 was prepared by rapid quenching of a homogenous Zr60Ti14.67Nb5.33Cu5.56Ni4.44Be10 melt, and characterized by means of X-ray diffraction (XRD, scanning electron microscopy (SEM observation and room-temperature compression test. The microstructure and mechanical properties were compared with those of the spherical β-phase reinforced composite named as composite S2. It was found that the composite D2 contains β-phase dendrites up to 56% in volume-fraction, and exhibits a ductile compressive behavior with plastic strain of 12.7%. As the high-volume-fractioned β-phase dendrites transferred to coarse spherical particles of about 20 μm in diameter in the composite S2, a much improved plastic strain up to 20.4% can be achieved. Micrographs of the fractured samples reveal different interaction modes of the propagating shear bands with the dendritic and spherical β phase inclusions, resulting in different shear strains in the composite samples. The matrix of composite S2 undergoes a significantly larger shear strain than that of the composite D2 before ultimate failure, which is thought to be mainly responsible for the greatly increased global plastic strain of the S2 relative to D2.
Kinsey, Erin; Pales, Ashley; Li, Chunyan; Mu, Linlin; Bai, Lingyun; Clifford, Heather; Darnault, Christophe
2016-04-01
Oil in water emulsions occur during oil extraction due to the presence of water, naturally-occurring surface-active agents and mechanical mixing in pipelines or from oil spillage. Emulsions present difficulties for use of oil in fuel and their rheological properties are important to treat environmental impacts of spills. The objective of this study is to assess the rheological characteristics of oil in water emulsions stabilized by 5% NaCl brine, Tween 20 surfactant and silica nanoparticles to gain knowledge about the behavior of oil flow in pipelines and characterize them for environmental applications. Rheological behaviors such as shear rate, shear stress, and viscosity of Prudhoe Bay crude oil emulsions were analyzed with varying percent of water volume fractions (12.5, 25 and 50%), varying weight percent of silica nanoparticles (0.001, 0.01 and 0.1 weight %), with and without 2 CMC Tween 20 nonionic surfactant. Emulsions with varying water volume fractions were analyzed at 20, 40 and 60 degrees Celsius. Flow curve analysis of the emulsions was performed using an Anton-Paar rheometer. Preliminary findings indicate that increased temperature and increasing the concentration of nanoparticles both produced lower shear stress and that the addition of surfactant decreased the viscosity and shear stress of the emulsions.
Variability in venom volume, flow rate and duration in defensive stings of five scorpion species.
van der Meijden, Arie; Coelho, Pedro; Rasko, Mykola
2015-06-15
Scorpions have been shown to control their venom usage in defensive encounters, depending on the perceived threat. Potentially, the venom amount that is injected could be controlled by reducing the flow speed, the flow duration, or both. We here investigated these variables by allowing scorpions to sting into an oil-filled chamber, and recording the accreting venom droplets with high-speed video. The size of the spherical droplets on the video can then be used to calculate their volume. We recorded defensive stings of 20 specimens representing 5 species. Significant differences in the flow rate and total expelled volume were found between species. These differences are likely due to differences in overall size between the species. Large variation in both venom flow speed and duration are described between stinging events of single individuals. Both venom flow rate and flow duration correlate highly with the total expelled volume, indicating that scorpions may control both variables in order to achieve a desired end volume of venom during a sting.
On the Generalized Mass Transport Equation to the Concept of Variable Fractional Derivative
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Abdon Atangana
2014-01-01
Full Text Available The hydrodynamic dispersion equation was generalized using the concept of variational order derivative. The modified equation was numerically solved via the Crank-Nicholson scheme. The stability and convergence of the scheme in this case were presented. The numerical simulations showed that, the modified equation is more reliable in predicting the movement of pollution in the deformable aquifers, than the constant fractional and integer derivatives.
Energy Technology Data Exchange (ETDEWEB)
Pai, M. S. [College of Medicine, Univ. of Ewha, Seoul (Korea, Republic of); Moon, D. H.; Kim, H. M.; Yang, Y. J.; Kang, D. H. [Asan Medical Center, Seoul (Korea, Republic of)
2003-07-01
Electrocardiogram-gated TI-201 SPECT measurements of left ventricular ejection fraction (EF), end-diastolic volume (EDV), and end-systolic volume (ESV) have shown high correlation with conventional methods. However, how much these parameters measured by TI-201 gated SPECT differ from those by echocardiography has not been assessed. Adenosine stress (Ad-G) and redistribution TI-201 gated SPECT (Re-G) and resting echocardiography were conducted in 337 patients (184 male, 153 female). EDV, ESV and LVEF measured by QGS software were compared with the results by echocardiography. Patients with arrhythmia (atrial fibrillation or frequent premature contractions) or evidence of fixed or reversible perfusion defects on TI-201 SPECT were excluded. EF, EDV and ESV measured by Ad-G (63.3{+-}9.8,73.8{+-}30.2,29.1{+-}20.1) and Re-G (65.2{+-}11.6,69.1{+-}30.1,26.5{+-}20.3) correlated well with those by Echo (61.4{+-}7.9,78.3{+-}2.7, 30.7{+-} 17.5 ; r of Ad-G=0.547, 0.850, 0.827, p<0.001 ; r of Re-G=0.585, 0.838, 0.819, p<0.001). However the difference (mean, SD, SEE of Echo - gated SPECT) was statistically significant (EF: Ad-G=1.71, 8.92, 0.48, Re-G=3.59, 10.39, 0.56, p<0.001 ; EDV: Ad-G=4.75, 16.21, 0.88, Re-G=9.53, 16.77, 0.91, p<0.001 ; ESV: Ad-G=1.75, 11.35, 0.61, p<0.05, Re-G=4.29, 11.7, 0.63, p<0.001). Bland-Altman plots showed that the difference of EDV and ESV did not vary in any systematic way over the range of measurement, whereas the difference of EF increased with increasing average EF by Echo and gated-SPECT. The difference of EF, EDV, and ESV between Ad-G and Echo was significantly smaller than those between Re-G and Echo (p<0.001). Gated TI-201 SPECT underestimates EDV and ESV over a wide range of volume. As a result, EF by gated TI-201 SPECT is overestimated especially in patients with small LV volume. Ad-G is preferable to Re-G in assessing left ventricular ejection fraction and volume in place of Echo because of smaller bias.
Variability of Arctic sea ice thickness and volume from CryoSat-2.
Kwok, R; Cunningham, G F
2015-07-13
We present our estimates of the thickness and volume of the Arctic Ocean ice cover from CryoSat-2 data acquired between October 2010 and May 2014. Average ice thickness and draft differences are within 0.16 m of measurements from other sources (moorings, submarine, electromagnetic sensors, IceBridge). The choice of parameters that affect the conversion of ice freeboard to thickness is discussed. Estimates between 2011 and 2013 suggest moderate decreases in volume followed by a notable increase of more than 2500 km(3) (or 0.34 m of thickness over the basin) in 2014, which could be attributed to not only a cooler summer in 2013 but also to large-scale ice convergence just west of the Canadian Arctic Archipelago due to wind-driven onshore drift. Variability of volume and thickness in the multiyear ice zone underscores the importance of dynamics in maintaining the thickness of the Arctic ice cover. Volume estimates are compared with those from ICESat as well as the trends in ice thickness derived from submarine ice draft between 1980 and 2004. The combined ICESat and CryoSat-2 record yields reduced trends in volume loss compared with the 5 year ICESat record, which was weighted by the record-setting ice extent after the summer of 2007.
Samus', N. N.; Durlevich, O. V.; Zharova, A. V.; Kazarovets, E. V.; Kireeva, N. N.; Pastukhova, E. N.; Williams, D. B.; Hazen, M. L.
2006-04-01
We present a new electronic version of the third volume of the fourth edition of the General Catalogue of Variable Stars (GCVS) that contains data on 13 855 variables in the constellations Pavo-Vulpecula. The Name Lists of Variable Stars from no. 67 to no. 77 were included in the new version. The main distinctive feature of the new version is that improved J2000.0 equatorial coordinates (including those for 6163 stars corrected for the proper motions) based on the identifications with positional catalogues using finding charts and on our new measurements are presented for 13 812 stars. We searched for a number of stars on original plates from the plate stacks of several observatories and using images from digital sky surveys. Apart from the complete update of the positional information, we made several corrections that were found to be necessary after the publication of the GCVS Volume III (1985) and several corrections of the information about the variability features based on photometry from currently available automatic sky surveys. A number of problem identifications are described in detail. The new version completes our long-term work on the complete revision of the positional information in the GCVS. In the Conclusions, we give a list of references to new Internet resources.
Thulborn, Keith; Lui, Elaine; Guntin, Jonathan; Jamil, Saad; Sun, Ziqi; Claiborne, Theodore C; Atkinson, Ian C
2016-02-01
Sodium ion homeostasis is a fundamental property of viable tissue, allowing the tissue sodium concentration to be modeled as the tissue cell volume fraction. The modern neuropathology literature using ex vivo tissue from selected brain regions indicates that human brain cell density remains constant during normal aging and attributes the volume loss that occurs with advancing age to changes in neuronal size and dendritic arborization. Quantitative sodium MRI performed with the enhanced sensitivity of ultrahigh-field 9.4 T has been used to investigate tissue cell volume fraction during normal aging. This cross-sectional study (n = 49; 21-80 years) finds that the in vivo tissue cell volume fraction remains constant in all regions of the brain with advancing age in individuals who remain cognitively normal, extending the ex vivo literature reporting constant neuronal cell density across the normal adult age range. Cell volume fraction, as measured by quantitative sodium MRI, is decreased in diseases of cell loss, such as stroke, on a time scale of minutes to hours, and in response to treatment of brain tumors on a time scale of days to weeks. Neurodegenerative diseases often have prodromal periods of decades in which regional neuronal cell loss occurs prior to clinical presentation. If tissue cell volume fraction can detect such early pathology, this quantitative parameter may permit the objective measurement of preclinical disease progression. This current study in cognitively normal aging individuals provides the basis for the pursuance of investigations directed towards such neurodegenerative diseases.
Directory of Open Access Journals (Sweden)
Natasha Samko
2010-01-01
Full Text Available We consider non-standard Hölder spaces Hλ(⋅(X of functions f on a metric measure space (X, d, μ, whose Hölder exponent λ(x is variable, depending on x ∈ X. We establish theorems on mapping properties of potential operators of variable order α(x, from such a variable exponent Hölder space with the exponent λ(x to another one with a “better” exponent λ(x + α(x, and similar mapping properties of hypersingular integrals of variable order α(x from such a space into the space with the “worse” exponent λ(x − α(x in the case α(x 0. We admit variable complex valued orders α(x, where ℜα(x may vanish at a set of measure zero. To cover this case, we consider the action of potential operators to weighted generalized Hölder spaces with the weight α(x.
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S Saha Ray
2016-05-01
Full Text Available This article presents the formulation and a new approach to find analytic solutions for fractional continuously variable order dynamic models, namely, fractional continuously variable order mass–spring–damper systems. Here, we use the viscoelastic and viscous–viscoelastic dampers for describing the damping nature of the oscillating systems, where the order of fractional derivative varies continuously. Here, we handle the continuous changing nature of fractional order derivative for dynamic systems, which has not been studied yet. By successive recursive method, here we find the solution of fractional continuously variable order mass–spring–damper systems and then obtain closed-form solutions. We then present and discuss the solutions obtained in the cases with continuously variable order of damping for oscillator through graphical plots.
Meyer, A.; Penning, H.; Elsner, M.
2009-04-01
Even after legislative prohibition in 1991 by the European Union, the pesticide atrazine and its metabolites are still detected in surface and ground water frequently exceeding the permitted drinking water concentration limit of 0,1 g/L. Despite much recent research on atrazine, its risk assessment in the environment is still a major challenge because of the difficulty of establishing mass balances in the subsurface. To obtain a better insight into the fate of atrazine, we developed compound-specific stable isotope analysis (CSIA) for atrazine. CSIA has proven valuable for assessing organic contaminants in subsurface environments, on the one hand for source identification and on the other hand to trace (bio)chemical degradation reactions through isotope fractionation in the compounds. Such assessment is based on the Rayleigh equation and therein on the isotope enrichment factor É, which must be determined experimentally beforehand. In ongoing work, we therefore measured carbon and nitrogen isotope fractionation associated with biotic hydrolsis of atrazine. C and N isotope enrichment factors were determined in resting cell experiments for Pseudomonas sp. ADP, Chelatobacter heintzii and Arthrobacter aurescens TC1, strains that hydrolyse atrazine in the initial transformation reaction. Carbon and nitrogen isotope enrichment factors were distinctly different between the bacterial strains. However, when plotting shifts in carbon isotope ratios versus shifts in nitrogen isotope ratios the slopes of the different degradation experiments coincided well. These results give evidence that all bacterial strains were carrying out the same initial biochemical degradation reaction, but that the associated isotope fractionation, as represented by the enrichment factors, was masked to a different extent owing to different rate determining steps prior to the isotopically sensitive bond cleavage (commitment to catalysis). Our study therefore illustrates the benefit of multi
Directory of Open Access Journals (Sweden)
A. H. Bhrawy
2013-01-01
Full Text Available We propose Jacobi-Gauss-Lobatto collocation approximation for the numerical solution of a class of fractional-in-space advection-dispersion equation with variable coefficients based on Caputo derivative. This approach has the advantage of transforming the problem into the solution of a system of ordinary differential equations in time this system is approximated through an implicit iterative method. In addition, some of the known spectral collocation approximations can be derived as special cases from our algorithm if we suitably choose the corresponding special cases of Jacobi parameters and . Finally, numerical results are provided to demonstrate the effectiveness of the proposed spectral algorithms.
2D and 3D milled surface roughness of high volume fraction SiCp/Al composites
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Tao Wang
2015-06-01
Full Text Available This paper presents a study on surface roughness generated by high speed milling of high volume fraction (65% silicon carbide particle-reinforced aluminum matrix (SiCp/Al composites. Typical 2D (Ra and Rz and 3D (Sa and Sq surface roughness parameters were selected to evaluate the influence of the milling parameters on the surface quality in comparison with aluminum alloy. The 3D topography of the milled surface was studied as well. The results indicate that 3D parameters (Sa and Sq are more capable to describe the influence of the milling parameters on the surface quality, and among them Sq is preferable due to its good sensitivity. Sq decreases with milling speed and increases with feed rate. The influence of axial depth of cut (ADOC is negligible.
DEFF Research Database (Denmark)
Wejdemann, Christian; Poulsen, Henning Friis; Lienert, U.
2009-01-01
The evolution of dislocation structures in individual bulk grains in copper during strain path changes is studied with a new in situ synchrotron technique which combines high angular resolution with fast three-dimensional reciprocal space mapping. Deformed copper contains regions with vanishing...... dislocation density called subgrains bounded by dislocation rich walls. With the new technique reciprocal space maps, consisting of sharp peaks arising from the subgrains superimposed on a cloud of lower intensity arising from the dislocation walls, are obtained, which allows properties such as subgrain...... volume fraction to be quantified. The studied strain path changes are tension-tension sequences. Polycrystalline copper sheets are pre-deformed in tension to 5% strain, and tensile samples are cut with varying angles between the first and second loading axis. The second tensile deformation up...
Rocha, Paulo; Raischel, Frank; Boto, João P.; Lind, Pedro G.
2016-05-01
We present a framework for describing the evolution of stochastic observables having a nonstationary distribution of values. The framework is applied to empirical volume-prices from assets traded at the New York Stock Exchange, about which several remarks are pointed out from our analysis. Using Kullback-Leibler divergence we evaluate the best model out of four biparametric models commonly used in the context of financial data analysis. In our present data sets we conclude that the inverse Γ distribution is a good model, particularly for the distribution tail of the largest volume-price fluctuations. Extracting the time series of the corresponding parameter values we show that they evolve in time as stochastic variables themselves. For the particular case of the parameter controlling the volume-price distribution tail we are able to extract an Ornstein-Uhlenbeck equation which describes the fluctuations of the highest volume-prices observed in the data. Finally, we discuss how to bridge the gap from the stochastic evolution of the distribution parameters to the stochastic evolution of the (nonstationary) observable and put our conclusions into perspective for other applications in geophysics and biology.
Equations of bark thickness and volume profiles at different heights with easy-measurement variables
Energy Technology Data Exchange (ETDEWEB)
Cellini, J. M.; Galarza, M.; Burns, S. L.; Martinez-Pastur, G. J.; Lencinas, M. V.
2012-11-01
The objective of this work was to develop equations of thickness profile and bark volume at different heights with easy-measurement variables, taking as a study case Nothofagus pumilio forests, growing in different site qualities and growth phases in Southern Patagonia. Data was collected from 717 harvested trees. Three models were fitted using multiple, non-lineal regression and generalized linear model, by stepwise methodology, iteratively reweighted least squares method for maximum likelihood estimation and Marquardt algorithm. The dependent variables were diameter at 1.30 m height (DBH), relative height (RH) and growth phase (GP). The statistic evaluation was made through the adjusted determinant coefficient (r2-adj), standard error of the estimation (SEE), mean absolute error and residual analysis. All models presented good fitness with a significant correlation with the growth phase. A decrease in the thickness was observed when the relative height increase. Moreover, a bark coefficient was made to calculate volume with and without bark of individual trees, where significant differences according to site quality of the stands and DBH class of the trees were observed. It can be concluded that the prediction of bark thickness and bark coefficient is possible using DBH, height, site quality and growth phase, common and easy measurement variables used in forest inventories. (Author) 23 refs.
Institute of Scientific and Technical Information of China (English)
X.P. Tan; J.L. Liu; X P Song; T. Jin; X.F. Sun; Z.Q. Hu
2011-01-01
A conventional X-ray difFractometer has been used to determine the -y/y＇ lattice misfit and γ＇ volume fraction for a Ru-containing nickel-based single crystal superalloy at room temperature. The rocking curve was used to characterize the distribution of subgrains. The diffraction peaks obtained by w-20 scan were used to determine the γ/γ＇ lattice misfit and γ＇ volume fraction. A three peaks fitting model was proposed. The peak fitting results are in good agreement with the model. The X-ray diffraction results indicate that the nickel-based single crystal superalloy was not a perfect monocrystalline material, which is comprised of many subgrains; and each subgrain also consists of large numbers of mosaic structures. In addition, two anomalous reflection phenomena were found during the experiment and discussed with respect to their occurrence and impact on the measurement. The experimental results show that the γ/γ＇ lattice misfit and ~/r volume fraction will be various at the different regions of its dendritic microstructure. The average γ/γ＇ lattice misfit and γ＇ volume fraction of the experimental alloy are approximately-0.2% and 70%, respectively. Furthermore, the γ＇ volume fraction calculated by atom microprobe （AP） data is also basically consistent with the experimental results.
Gould, L; Gopalaswamy, C; Yang, D; Patel, D; Kim, B S; Patel, C; Becker, W H
1985-11-01
A first-pass nuclear angiogram and a multiple-gated acquisition study were obtained in 10 normal physicians and in 10 patients with a 7-to-10 day old transmural myocardial infarction. After the scan the subjects drank 2 oz. of whiskey. After 60 minutes, the multiple-gated acquisition study was repeated. In the normal group the left ventricular ejection fraction was 68% before and 72% after alcohol. The left ventricular end-diastolic volume increased from 89 to 97 ml while the left ventricular end-systolic volume decreased from 29 to 27 ml. The stroke volume rose from 61 to 70 ml/beat (p less than 0.05). The cardiac output increased from 4.0 to 5.0 l/min (p less than 0.05). In the infarction group, the left ventricular ejection fraction was 58% before and 56% after alcohol administration. The left ventricular end-diastolic volume fell from 111 to 96 ml, while the left ventricular end-systolic volume declined from 50 to 44 ml. The stroke volume fell from 61 to 52 ml/beat, while the cardiac output fell from 4.5 to 3.8 l/min. In the left ventricular infarction zones, alcohol produced in 9 of the 10 cardiac patients a decline in the left ventricular regional ejection fraction. In the normal group, alcohol produced no significant changes in the regional ejection fraction. The normal and the postinfarction patients responded differently to alcohol.
Directory of Open Access Journals (Sweden)
Rajagopalan Parameshwaran
2008-01-01
Full Text Available In the quest for energy conservative building design, there is now a great opportunity for a flexible and sophisticated air conditioning system capable of addressing better thermal comfort, indoor air quality, and energy efficiency, that are strongly desired. The variable refrigerant volume air conditioning system provides considerable energy savings, cost effectiveness and reduced space requirements. Applications of intelligent control like fuzzy logic controller, especially adapted to variable air volume air conditioning systems, have drawn more interest in recent years than classical control systems. An experimental analysis was performed to investigate the inherent operational characteristics of the combined variable refrigerant volume and variable air volume air conditioning systems under fixed ventilation, demand controlled ventilation, and combined demand controlled ventilation and economizer cycle techniques for two seasonal conditions. The test results of the variable refrigerant volume and variable air volume air conditioning system for each techniques are presented. The test results infer that the system controlled by fuzzy logic methodology and operated under the CO2 based mechanical ventilation scheme, effectively yields 37% and 56% per day of average energy-saving in summer and winter conditions, respectively. Based on the experimental results, the fuzzy based combined system can be considered to be an alternative energy efficient air conditioning scheme, having significant energy-saving potential compared to the conventional constant air volume air conditioning system.
Spathis, G.; Kontou, E.
2017-06-01
In the present work, the nonlinear viscoelastic/viscoplastic response of polymeric materials is described by introducing essential modifications on a model developed in previous works. A constitutive equation of viscoelasticity, based on the transient network theory, is introduced in a more generalized form, which takes into account volume changes during deformation. This time-dependent equation accounts for the nonlinearity and viscoplasticity at small elastic and finite plastic strain regime. The present description was proved to be more flexible, given that it contains a relaxation function that has been derived by considering instead of first order kinetics a fractional derivative that controls the rate of molecular chain detachment from their junctions. Therefore, the new equation has a more global character, appropriate for cases where heavy tails are expected. On the basis of the distributed nature of free volume, a new functional form of the rate of plastic deformation is developed, which is combined with a proper kinematic formulation and leads to the separation of the total strain into the elastic and plastic part. A three-dimensional constitutive equation is then derived for an isotropic, compressible medium. This analysis was proved to be capable of capturing the main aspects of inelastic response as well as the instability stage taking place at the tertiary creep, related to the creep failure.
An hybrid finite volume finite element method for variable density incompressible flows
Calgaro, Caterina; Creusé, Emmanuel; Goudon, Thierry
2008-04-01
This paper is devoted to the numerical simulation of variable density incompressible flows, modeled by the Navier-Stokes system. We introduce an hybrid scheme which combines a finite volume approach for treating the mass conservation equation and a finite element method to deal with the momentum equation and the divergence free constraint. The breakthrough relies on the definition of a suitable footbridge between the two methods, through the design of compatibility condition. In turn, the method is very flexible and allows to deal with unstructured meshes. Several numerical tests are performed to show the scheme capabilities. In particular, the viscous Rayleigh-Taylor instability evolution is carefully investigated.
Directory of Open Access Journals (Sweden)
Bas Versluis
Full Text Available OBJECTIVES: The aim of the current study was to describe a method that assesses the hyperemic microvascular blood plasma volume of the calf musculature. The reversibly albumin binding contrast agent gadofosveset was used in dynamic contrast-enhanced magnetic resonance imaging (DCE MRI to assess the microvascular status in patients with peripheral arterial disease (PAD and healthy controls. In addition, the reproducibility of this method in healthy controls was determined. MATERIALS AND METHODS: Ten PAD patients with intermittent claudication and 10 healthy control subjects were included. Patients underwent contrast-enhanced MR angiography of the peripheral arteries, followed by one DCE MRI examination of the musculature of the calf. Healthy control subjects were examined twice on different days to determine normative values and the interreader and interscan reproducibility of the technique. The MRI protocol comprised dynamic imaging of contrast agent wash-in under reactive hyperemia conditions of the calf musculature. Using pharmacokinetic modeling the hyperemic fractional microvascular blood plasma volume (V(p, unit: % of the anterior tibial, gastrocnemius and soleus muscles was calculated. RESULTS: V(p was significantly lower for all muscle groups in PAD patients (4.3±1.6%, 5.0±3.3% and 6.1±3.6% for anterior tibial, gastrocnemius and soleus muscles, respectively compared to healthy control subjects (9.1±2.0%, 8.9±1.9% and 9.3±2.1%. Differences in V(p between muscle groups were not significant. The coefficient of variation of V(p varied from 10-14% and 11-16% at interscan and interreader level, respectively. CONCLUSIONS: Using DCE MRI after contrast-enhanced MR angiography with gadofosveset enables reproducible assessment of hyperemic fractional microvascular blood plasma volume of the calf musculature. V(p was lower in PAD patients than in healthy controls, which reflects a promising functional (hemodynamic biomarker for the
Sun, HongGuang; Zhang, Yong; Chen, Wen; Reeves, Donald M.
2014-02-01
Field and numerical experiments of solute transport through heterogeneous porous and fractured media show that the growth of contaminant plumes may not exhibit constant scaling, and may instead transition between diffusive states (i.e., superdiffusion, subdiffusion, and Fickian diffusion) at various transport scales. These transitions are likely attributed to physical properties of the medium, such as spatial variations in medium heterogeneity. We refer to this transitory dispersive behavior as "transient dispersion", and propose a variable-index fractional-derivative model (FDM) to describe the underlying transport dynamics. The new model generalizes the standard constant-index FDM which is limited to stationary heterogeneous media. Numerical methods including an implicit Eulerian method (for spatiotemporal transient dispersion) and a Lagrangian solver (for multiscaling dispersion) are utilized to produce variable-index FDM solutions. The variable-index FDM is then applied to describe transient dispersion observed at two field tracer tests and a set of numerical experiments. Results show that 1) uranine transport at the small-scale Grimsel test site transitions from strong subdispersion to Fickian dispersion, 2) transport of tritium at the regional-scale Macrodispersion Experimental (MADE) site transitions from near-Fickian dispersion to strong superdispersion, and 3) the conservative particle transport through regional-scale discrete fracture network transitions from superdispersion to Fickian dispersion. The variable-index model can efficiently quantify these transitions, with the scale index varying linearly in time or space.
Sun, Hongguang; Zhang, Yong; Chen, Wen; Reeves, Donald M
2014-02-01
Field and numerical experiments of solute transport through heterogeneous porous and fractured media show that the growth of contaminant plumes may not exhibit constant scaling, and may instead transition between diffusive states (i.e., superdiffusion, subdiffusion, and Fickian diffusion) at various transport scales. These transitions are likely attributed to physical properties of the medium, such as spatial variations in medium heterogeneity. We refer to this transitory dispersive behavior as "transient dispersion", and propose a variable-index fractional-derivative model (FDM) to describe the underlying transport dynamics. The new model generalizes the standard constant-index FDM which is limited to stationary heterogeneous media. Numerical methods including an implicit Eulerian method (for spatiotemporal transient dispersion) and a Lagrangian solver (for multiscaling dispersion) are utilized to produce variable-index FDM solutions. The variable-index FDM is then applied to describe transient dispersion observed at two field tracer tests and a set of numerical experiments. Results show that 1) uranine transport at the small-scale Grimsel test site transitions from strong subdispersion to Fickian dispersion, 2) transport of tritium at the regional-scale Macrodispersion Experimental (MADE) site transitions from near-Fickian dispersion to strong superdispersion, and 3) the conservative particle transport through regional-scale discrete fracture network transitions from superdispersion to Fickian dispersion. The variable-index model can efficiently quantify these transitions, with the scale index varying linearly in time or space.
Directory of Open Access Journals (Sweden)
Kanda H
2015-09-01
Full Text Available Hirotsugu Kanda,1 Yuji Hirasaki,2 Takafumi Iida,1 Megumi Kanao,1 Yuki Toyama,1 Takayuki Kunisawa,1 Hiroshi Iwasaki,11Department of Anesthesiology and Critical Care Medicine, Asahikawa Medical University, Asahikawa, 2Department of Anatomy, The Jikei University Graduate School of Medicine, Tokyo, JapanPurpose: The aim of this clinical trial was to investigate changes in stroke volume variability (SVV and left ventricular end-diastolic volume (LVEDV after a fluid bolus of crystalloid or colloid using real-time three-dimensional transesophageal echocardiography (3D-TEE and the Vigileo-FloTrac™ system.Materials and methods: After obtaining Institutional Review Board approval, and informed consent from the research participants, 22 patients undergoing scheduled peripheral vascular bypass surgery were enrolled in the study. The patients were randomly assigned to receive 500 mL of hydroxyethyl starch (HES; HES group, n=11 or normal saline (Saline group, n=11 for fluid replacement therapy. SVV was measured using the Vigileo-FloTrac system. LVEDV, stroke volume, and cardiac output were measured by 3D-TEE. The measurements were performed over 30 minutes before and after the fluid bolus in both groups.Results: SVV significantly decreased after fluid bolus in both groups (HES group, 14.7%±2.6% to 6.9%±2.7%, P<0.001; Saline group, 14.3%±3.9% to 8.8%±3.1%, P<0.001. LVEDV significantly increased after fluid loading in the HES group (87.1±24.0 mL to 99.9±27.2 mL, P<0.001, whereas no significant change was detected in the Saline group (88.8±17.3 mL to 91.4±17.6 mL, P>0.05. Stroke volume significantly increased after infusion in the HES group (50.6±12.5 mL to 61.6±19.1 mL, P<0.01 but not in the Saline group (51.6±13.4 mL to 54.1±12.8 mL, P>0.05. Cardiac output measured by 3D-TEE significantly increased in the HES group (3.5±1.1 L/min to 3.9±1.3 L/min, P<0.05, whereas no significant change was seen in the Saline group (3.4±1.1 L/min to 3.3±1.0 L
DEFF Research Database (Denmark)
Sørensen, Flemming Brandt; Braendgaard, H; Chistiansen, A O
1991-01-01
the practical technique. The continuous variables were correlated with the subjective, qualitative WHO classification of brain tumors, and the prognostic value of the parameters was assessed. Well differentiated astrocytomas (n = 14) had smaller estimates of the volume-weighted mean nuclear volume and mean...
Air-kerma determination using a variable-volume cavity ionization chamber standard.
Burns, D T; Kessler, C; Roger, P
2007-12-01
A graphite-walled cavity ionization chamber of modular design and variable volume has been used to determine the air-kerma rate in the reference 60Co field at the BIPM. The chamber can be configured in five sizes. High-accuracy mechanical measurements of the volume of the air cavity were made for each configuration using a co-ordinate measuring machine. Ionization current measurements were made for each configuration and corrected for the effects of ion recombination and diffusion, stem scatter and chamber orientation. Monte Carlo calculations of cavity dose were made to evaluate the correction factors kwall and kan. A reproducibility of the ionization current per mass of 1.5 parts in 10(4) was achieved on the repeated assembly of each configuration. The results show an air-kerma rate determination that increases with volume, the total change being around 8 parts in 10(4). When analysed differentially, the air-kerma rate relative to the BIPM standard is Kdiff/KBIPM = 1.0026(6). A detailed uncertainty budget is presented. Possible reasons for the observed behaviour are discussed that might have consequences for all existing standards for air-kerma.
Evans, S. L.; Anderson, W. T.; Jochem, F. J.; Fourqurean, J. W.
2004-12-01
Environmental conditions in South Florida coastal waters have been of local and national concern over the past 15 years. Attention has focused on the ecosystem impacts of salinity increases, seagrass die-off, increased algal bloom frequency, waste water influence, groundwater discharge, and exchange between Florida Bay, the Gulf of Mexico, and the Atlantic Ocean. Changes in water quality and productivity levels may be reflected in the isotopic signatures of coastal zone primary producers. Recent work with seagrasses in South Florida has demonstrated high seasonal and spatial variability in C and N isotopic signatures and decoupling between the two isotopic systems as they vary. To better understand the sources of seasonal and spatial fluctuation, size fractionated POM (particulate organic matter) samples have been collected on a quarterly basis since Sept. 2002. Fractions collected include >150μ m, 50-150μ m, and 0.1-50μ m using Nitex mesh sieves and a portable pump system deployed from a small boat at 10 sites around the Florida Keys and Florida Bay. It was hypothesized that planktonic groups respond more quickly to changes in water quality then seagrasses, and thus variations may be more clearly attributed to environmental parameters. Significant spatial and temporal variability is evident both within site between size fractions and between sites. Seasonal oscillations of up to 4‰ were observed in N isotopic values and 6‰ in C isotopic values of the 50-150μ m size fraction, which is dominated by diatoms and dinoflagellates. δ 13C values are depleted in the late winter/early spring sampling period possibly reflecting decreased productivity stress on available C pools. 13C depletion is generally coincident with δ 15N enrichment in the late winter/early spring, possibly demonstrating changes in DIN pools (NO3- and NH4+ concentrations) or changes in decomposition or denitrification rates. Broad groupings appear to separate Atlantic coral reef sites
Wang, Lile; Ju, Wenhua; Rafikov, Roman R; Ruan, John J; Schneider, Donald P
2016-01-01
Supermassive black hole binaries (SMBHs) are expected to result from galaxy mergers, and thus are natural byproducts (and probes) of hierarchical structure formation in the Universe. They are also the primary expected source of low-frequency gravitational wave emission. We search for binary BHs using time-variable velocity shifts in broad Mg II emission lines of quasars with multi-epoch observations. First, we inspect velocity shifts of the binary SMBH candidates identified in Ju et al. (2013), using SDSS spectra with an additional epoch of data that lengthens the typical baseline to ~10 yr. We find variations in the line-of-sight velocity shifts over 10 years that are comparable to the shifts observed over 1-2 years, ruling out the binary model for the bulk of our candidates. We then analyze 1438 objects with 8 yr median time baselines, from which we would expect to see velocity shifts >1000 km/s from sub-pc binaries. We find only one object with an outlying velocity of 448 km/s, indicating, based on our mod...
Niche-specificity and the variable fraction of the Pectobacterium pan-genome.
Glasner, J D; Marquez-Villavicencio, M; Kim, H-S; Jahn, C E; Ma, B; Biehl, B S; Rissman, A I; Mole, B; Yi, X; Yang, C-H; Dangl, J L; Grant, S R; Perna, N T; Charkowski, A O
2008-12-01
We compare genome sequences of three closely related soft-rot pathogens that vary in host range and geographical distribution to identify genetic differences that could account for lifestyle differences. The isolates compared, Pectobacterium atrosepticum SCRI1043, P. carotovorum WPP14, and P. brasiliensis 1692, represent diverse lineages of the genus. P. carotovorum and P. brasiliensis genome contigs, generated by 454 pyrosequencing ordered by reference to the previously published complete circular chromosome of P. atrosepticum genome and each other, account for 96% of the predicted genome size. Orthologous proteins encoded by P. carotovorum and P. brasiliensis are approximately 95% identical to each other and 92% identical to P. atrosepticum. Multiple alignment using Mauve identified a core genome of 3.9 Mb conserved among these Pectobacterium spp. Each core genome is interrupted at many points by species-specific insertions or deletions (indels) that account for approximately 0.9 to 1.1 Mb. We demonstrate that the presence of a hrpK-like type III secretion system-dependent effector protein in P. carotovorum and P. brasiliensis and its absence from P. atrosepticum is insufficient to explain variability in their response to infection in a plant. Additional genes that vary among these species include those encoding peptide toxin production, enzyme production, secretion proteins, and antibiotic production, as well as differences in more general aspects of gene regulation and metabolism that may be relevant to pathogenicity.
Wang, Lile; Greene, Jenny E.; Ju, Wenhua; Rafikov, Roman R.; Ruan, John J.; Schneider, Donald P.
2017-01-01
Supermassive black hole binaries (SMBHs) are expected to result from galaxy mergers, and thus are natural byproducts (and probes) of hierarchical structure formation in the universe. They are also the primary expected source of low-frequency gravitational wave emission. We search for binary BHs using time-variable velocity shifts in broad Mg ii emission lines of quasars with multi-epoch observations. First, we inspect velocity shifts of the binary SMBH candidates identified in Ju et al., using Sloan Digital Sky Survey spectra with an additional epoch of data that lengthens the typical baseline to ∼10 yr. We find variations in the line of sight velocity shifts over 10 yr that are comparable to the shifts observed over 1–2 yr, ruling out the binary model for the bulk of our candidates. We then analyze 1438 objects with eight-year median time baselines, from which we would expect to see velocity shifts >1000 {km} {{{s}}}-1 from sub-parsec binaries. We find only one object with an outlying velocity of 448 {km} {{{s}}}-1, indicating—based on our modeling—that ≲1% (the value varies with different assumptions) of SMBHs that are active as quasars reside in binaries with ∼0.1 pc separations. Binaries either sweep rapidly through these small separations or stall at larger radii.
Hindel, Stefan; Söhner, Anika; Maa, Marc; Sauerwein, Wolfgang; Baba, Hideo Andreas; Kramer, Martin; Lüdemann, Lutz
2017-01-01
The aim of our study was to assess the accuracy of fractional interstitial volume determination in low perfused and low vascularized tissue by using dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). The fractional interstitial volume (ve) was determined in the medial thigh muscle of 12 female pigs by using a 3-dimensional gradient echo sequence with k-space sharing and administering gadolinium-based contrast agent (gadoterate meglumine). Analysis was performed using 3 pharmacokinetic models: the simple Tofts model (TM), the extended TM (ETM), and the 2-compartment exchange model (2CXM). We investigated the effect of varying acquisition durations (ADs) on the model parameter estimates of the 3 models and compared the ve values with the results of histological examinations of muscle sections of the medial thigh muscle. Histological measurements yielded a median value (25%-75% quartile) of 4.8% (3.7%-6.2%) for ve. The interstitial fractional volume determined by DCE-MRI was comparable to the histological results but varied strongly with AD for the TM and ETM. For the TM and the ETM, the results were virtually the same. Choosing arterial hematocrit to Hcta = 0.4, the lowest median ve value determined by DCE-MRI was 5.2% (3.3%-6.1%) for the ETM at a 6-minute AD. The maximum ve value determined with the ETM at a 15-minute AD was 7.7% (4.5%-9.0%). The variation with AD of median ve values obtained with the 2CXM was much smaller: 6.2% (3.1%-9.2%) for the 6-minute AD and 6.3% (4.3%-9.8%) for the 15-minute AD. The best fit for the 2CXM was found at the 10-minute AD with ve values of 6.6% (3.7%-8.2%). No significant correlation between the histological and any DCE-MRI modeling results was found. Considering the expected accuracy of histological measurements, the medians of the MR modeling results were in good agreement with the histological prediction. A parameter determination uncertainty was identified with the use of the TMs. This is due to underfitting and
2012-10-01
increasing the fiber-volume fraction by Vacuum Assisted Resin Transfer Molding ( VARTM ) in order to produce composite structures with aerospace grade...processed composites. Using a combination of viscosity control, U.S. Army Research Laboratory (ARL) based VARTM techniques, and a pressure control...system, we have shown an increase in fiber-volume content from 50% (ARL’s normal processing range for a particular material system and VARTM process) to
Mukherjee, Kanchan Kumar; Kumar, Narendra; Tripathi, Manjul; Oinam, Arun S; Ahuja, Chirag K; Dhandapani, Sivashanmugam; Kapoor, Rakesh; Ghoshal, Sushmita; Kaur, Rupinder; Bhatt, Sandeep
2017-01-01
To evaluate the feasibility, safety and efficacy of dose fractionated gamma knife radiosurgery (DFGKRS) on a daily schedule beyond the linear quadratic (LQ) model, for large volume arteriovenous malformations (AVMs). Between 2012-16, 14 patients of large AVMs (median volume 26.5 cc) unsuitable for surgery or embolization were treated in 2-3 of DFGKRS sessions. The Leksell G frame was kept in situ during the whole procedure. 86% (n = 12) patients had radiologic evidence of bleed, and 43% (n = 6) had presented with a history of seizures. 57% (n = 8) patients received a daily treatment for 3 days and 43% (n = 6) were on an alternate day (2 fractions) regimen. The marginal dose was split into 2 or 3 fractions of the ideal prescription dose of a single fraction of 23-25 Gy. The median follow up period was 35.6 months (8-57 months). In the three-fraction scheme, the marginal dose ranged from 8.9-11.5 Gy, while in the two-fraction scheme, the marginal dose ranged from 11.3-15 Gy at 50% per fraction. Headache (43%, n = 6) was the most common early postoperative complication, which was controlled with short course steroids. Follow up evaluation of at least three years was achieved in seven patients, who have shown complete nidus obliteration in 43% patients while the obliteration has been in the range of 50-99% in rest of the patients. Overall, there was a 67.8% reduction in the AVM volume at 3 years. Nidus obliteration at 3 years showed a significant rank order correlation with the cumulative prescription dose (p 0.95, P value 0.01), with attainment of near-total (more than 95%) obliteration rates beyond 29 Gy of the cumulative prescription dose. No patient receiving a cumulative prescription dose of less than 31 Gy had any severe adverse reaction. In co-variate adjusted ordinal regression, only the cumulative prescription dose had a significant correlation with common terminology criteria for adverse events (CTCAE) severity (P value 0.04), independent of age, AVM volume
Meng, Yiqing; Lucas, Gary P.
2017-05-01
This paper presents the design and implementation of an inductive flow tomography (IFT) system, employing a multi-electrode electromagnetic flow meter (EMFM) and novel reconstruction techniques, for measuring the local water velocity distribution in water continuous single and multiphase flows. A series of experiments were carried out in vertical-upward and upward-inclined single phase water flows and ‘water continuous’ gas-water and oil-gas-water flows in which the velocity profiles ranged from axisymmetric (single phase and vertical-upward multiphase flows) to highly asymmetric (upward-inclined multiphase flows). Using potential difference measurements obtained from the electrode array of the EMFM, local axial velocity distributions of the continuous water phase were reconstructed using two different IFT reconstruction algorithms denoted RT#1, which assumes that the overall water velocity profile comprises the sum of a series of polynomial velocity components, and RT#2, which is similar to RT#1 but which assumes that the zero’th order velocity component may be replaced by an axisymmetric ‘power law’ velocity distribution. During each experiment, measurement of the local water volume fraction distribution was also made using the well-established technique of electrical resistance tomography (ERT). By integrating the product of the local axial water velocity and the local water volume fraction in the cross section an estimate of the water volumetric flow rate was made which was compared with a reference measurement of the water volumetric flow rate. In vertical upward flows RT#2 was found to give rise to water velocity profiles which are consistent with the previous literature although the profiles obtained in the multiphase flows had relatively higher central velocity peaks than was observed for the single phase profiles. This observation was almost certainly a result of the transfer of axial momentum from the less dense dispersed phases to the water
Tapiero, Charles S.; Vallois, Pierre
2016-11-01
The premise of this paper is that a fractional probability distribution is based on fractional operators and the fractional (Hurst) index used that alters the classical setting of random variables. For example, a random variable defined by its density function might not have a fractional density function defined in its conventional sense. Practically, it implies that a distribution's granularity defined by a fractional kernel may have properties that differ due to the fractional index used and the fractional calculus applied to define it. The purpose of this paper is to consider an application of fractional calculus to define the fractional density function of a random variable. In addition, we provide and prove a number of results, defining the functional forms of these distributions as well as their existence. In particular, we define fractional probability distributions for increasing and decreasing functions that are right continuous. Examples are used to motivate the usefulness of a statistical approach to fractional calculus and its application to economic and financial problems. In conclusion, this paper is a preliminary attempt to construct statistical fractional models. Due to the breadth and the extent of such problems, this paper may be considered as an initial attempt to do so.
Onal, Cem; Cengiz, Mustafa; Guler, Ozan C; Dolek, Yemliha; Ozkok, Serdar
2017-05-01
To assess whether delineation courses for radiation oncologists improve interobserver variability in target volume delineation for post-operative gastric cancer radiotherapy planning. 29 radiation oncologists delineated target volumes in a gastric cancer patient. An experienced radiation oncologist lectured about delineation based on contouring atlas and delineation recommendations. After the course, the radiation oncologists, blinded to the previous delineation, provided delineation for the same patient. The difference between delineated volumes and reference volumes for pre- and post-course clinical target volume (CTV) were 19.8% (-42.4 to 70.6%) and 12.3% (-12.0 to 27.3%) (p = 0.26), respectively. The planning target volume (PTV) differences pre- and post-course according to the reference volume were 20.5% (-40.7 to 93.7%) and 13.1% (-10.6 to 29.5%) (p = 0.30), respectively. The concordance volumes between the pre- and post-course CTVs and PTVs were 467.1 ± 89.2 vs 597.7 ± 54.6 cm(3) (p target volume changes on toxicity and local control should be evaluated for further studies. Advances in knowledge: This study demonstrated that a delineation course based on current recommendations helped physicians delineate smaller and more homogeneous target volumes. Better target volume delineation allows proper target volume irradiation and preventing unnecessary normal tissue irradiation.
Bikakis, GSE; Savaidis, A.; Zalimidis, P.; Tsitos, S.
2016-11-01
Fiber-metal laminates are hybrid composite materials, consisting of alternating metal layers bonded to fiber-reinforced prepreg layers. GLARE (GLAss REinforced) belongs to this new family of materials. GLARE is the most successful fiber-metal laminate up to now and is currently being used for the construction of primary aerospace structures, such as the fuselage of the Airbus A380 air plane. Impact properties are very important in aerospace structures, since impact damage is caused by various sources, such as maintenance damage from dropped tools, collision between service cars or cargo and the structure, bird strikes and hail. The principal objective of this article is to evaluate the influence of the Metal Volume Fraction (MVF) on the low velocity impact response of GLARE fiber-metal laminates. Previously published differential equations of motion are employed for this purpose. The low velocity impact behavior of various circular GLARE plates is predicted and characteristic values of impact variables, which represent the impact phenomenon, are evaluated versus the corresponding MVF of the examined GLARE material grades. The considered GLARE plates are subjected to low velocity impact under identical impact conditions. A strong effect of the MVF on the maximum impact load and a significant effect on the maximum plate deflection of GLARE plates has been found.
Bikakis, GSE; Savaidis, A.; Zalimidis, P.; Tsitos, S.
2016-11-01
Fiber-metal laminates are hybrid composite materials, consisting of alternating metal layers bonded to fiber-reinforced prepreg layers. GLARE (GLAss REinforced) belongs to this new family of materials. GLARE is the most successful fiber-metal laminate up to now and is currently being used for the construction of primary aerospace structures, such as the fuselage of the Airbus A380 air plane. Impact properties are very important in aerospace structures, since impact damage is caused by various sources, such as maintenance damage from dropped tools, collision between service cars or cargo and the structure, bird strikes and hail. The principal objective of this article is to evaluate the influence of the Metal Volume Fraction (MVF) on the low velocity impact response of GLARE fiber-metal laminates. Previously published differential equations of motion are employed for this purpose. The low velocity impact behavior of various circular GLARE plates is predicted and characteristic values of impact variables, which represent the impact phenomenon, are evaluated versus the corresponding MVF of the examined GLARE material grades. The considered GLARE plates are subjected to low velocity impact under identical impact conditions. A strong effect of the MVF on the maximum impact load and a significant effect on the maximum plate deflection of GLARE plates has been found.
DEFF Research Database (Denmark)
Boas, Malene; Hegedüs, Laszlo; Feldt-Rasmussen, Ulla
2009-01-01
CONTEXT AND OBJECTIVE: Few studies have focused on the interrelation between thyroid size, anthropometric variables, and IGF-I in adults, but such data are lacking for children. We have investigated thyroid gland volume and several hormonal and anthropometric variables in prepubertal children...
Directory of Open Access Journals (Sweden)
Michele eBertazzini
2016-03-01
Full Text Available Numerous angiosperms rely on pollinators to ensure efficient flower fertilization, offering a reward consisting of nourishing nectars produced by specialized floral cells, known as nectaries. Nectar components are believed to derive from phloem sap that is enzymatically processed and transformed within nectaries. An increasing body of evidence suggests that nectar composition, mainly amino acids, may influence pollinator attraction and fidelity. This notwithstanding, little is known about the range of natural variability in nectar content for crop species. Sugar and amino acid composition of nectar harvested from field-grown plants at the 63 to 65 phenological stage was determined for a set of 44 winter genotypes of rapeseed, a bee-pollinated crop. Significant differences were found for solute concentrations, and an even higher variability was evident for nectar volumes, resulting in striking differences when results were expressed on a single flower basis. The comparison of nectar and phloem sap from a subset of 8 varieties pointed out qualitative and quantitative diversities with respect to both sugars and amino acids. Notably, amino acid concentration in phloem sap was up to one hundred times higher than in nectar. Phloem sap showed a much more uniform composition, suggesting that nectar variability depends mainly on nectary metabolism. A better understanding of the basis of nectar production would allow an improvement of seed set efficiency, as well as hive management and honey production.
Roy, Prasanta; Roy, Binoy Krishna
2016-07-01
The Quadruple Tank Process (QTP) is a well-known benchmark of a nonlinear coupled complex MIMO process having both minimum and nonminimum phase characteristics. This paper presents a novel self tuning type Dual Mode Adaptive Fractional Order PI controller along with an Adaptive Feedforward controller for the QTP. The controllers are designed based on a novel Variable Parameter Transfer Function model. The effectiveness of the proposed model and controllers is tested through numerical simulation and experimentation. Results reveal that the proposed controllers work successfully to track the reference signals in all ranges of output. A brief comparison with some of the earlier reported similar works is presented to show that the proposed control scheme has some advantages and better performances than several other similar works.
Novák, Jiří; Giesy, John P; Klánová, Jana; Hilscherová, Klára
2013-09-01
Chemicals in air were characterized for potential interference with signaling of estrogen, androgen, and arylhydrocarbon (AhR) receptors, which are known to play an important role in endocrine-disruptive changes in vivo. Previously, effects of this type have been studied mainly in particulate matter in the ambient air from various localities. In this study, both volatile and particulate fractions of air from three sites in Banja Luka region (Bosnia and Herzegovina) were investigated to describe the distribution of endocrine-disrupting contaminants on a small spatial scale. Circadian variability of air pollution was investigated by collecting samples during both day and night. Air samples collected from urban localities at night were more potent in producing the AhR-mediated effects than those collected during daytime. This trend was not observed at the reference rural location. None of the samples showed significant estrogenic or androgenic activity. On the other hand, anti-androgenicity was detected in both particulate and vapor phases, while anti-estrogenicity was detected only in the particulate fraction of air from all localities. The AhR-mediated potencies of samples were associated primarily with non-persistent compounds. Based on the concentrations of 28 individual compounds, PAHs accounted for approximately 30 % of the AhR-mediated potency determined by the bioassay. The results show that there can be a significant difference between levels of bioactive compounds in air between daytime and nighttime.
Del Bello, Elisabetta; Taddeucci, Jacopo; de’ Michieli Vitturi, Mattia; Scarlato, Piergiorgio; Andronico, Daniele; Scollo, Simona; Kueppers, Ulrich; Ricci, Tullio
2017-01-01
Most of the current ash transport and dispersion models neglect particle-fluid (two-way) and particle-fluid plus particle-particle (four-way) reciprocal interactions during particle fallout from volcanic plumes. These interactions, a function of particle concentration in the plume, could play an important role, explaining, for example, discrepancies between observed and modelled ash deposits. Aiming at a more accurate prediction of volcanic ash dispersal and sedimentation, the settling of ash particles at particle volume fractions (ϕp) ranging 10‑7-10‑3 was performed in laboratory experiments and reproduced by numerical simulations that take into account first the two-way and then the four-way coupling. Results show that the velocity of particles settling together can exceed the velocity of particles settling individually by up to 4 times for ϕp ~ 10‑3. Comparisons between experimental and simulation results reveal that, during the sedimentation process, the settling velocity is largely enhanced by particle-fluid interactions but partly hindered by particle-particle interactions with increasing ϕp. Combining the experimental and numerical results, we provide an empirical model allowing correction of the settling velocity of particles of any size, density, and shape, as a function of ϕp. These corrections will impact volcanic plume modelling results as well as remote sensing retrieval techniques for plume parameters.
Del Bello, Elisabetta; Taddeucci, Jacopo; de’ Michieli Vitturi, Mattia; Scarlato, Piergiorgio; Andronico, Daniele; Scollo, Simona; Kueppers, Ulrich; Ricci, Tullio
2017-01-01
Most of the current ash transport and dispersion models neglect particle-fluid (two-way) and particle-fluid plus particle-particle (four-way) reciprocal interactions during particle fallout from volcanic plumes. These interactions, a function of particle concentration in the plume, could play an important role, explaining, for example, discrepancies between observed and modelled ash deposits. Aiming at a more accurate prediction of volcanic ash dispersal and sedimentation, the settling of ash particles at particle volume fractions (ϕp) ranging 10−7-10−3 was performed in laboratory experiments and reproduced by numerical simulations that take into account first the two-way and then the four-way coupling. Results show that the velocity of particles settling together can exceed the velocity of particles settling individually by up to 4 times for ϕp ~ 10−3. Comparisons between experimental and simulation results reveal that, during the sedimentation process, the settling velocity is largely enhanced by particle-fluid interactions but partly hindered by particle-particle interactions with increasing ϕp. Combining the experimental and numerical results, we provide an empirical model allowing correction of the settling velocity of particles of any size, density, and shape, as a function of ϕp. These corrections will impact volcanic plume modelling results as well as remote sensing retrieval techniques for plume parameters. PMID:28045056
DNS of horizontal open channel flow with finite-size, heavy particles at low solid volume fraction
Kidanemariam, Aman G; Doychev, Todor; Uhlmann, Markus
2013-01-01
We have performed direct numerical simulation of turbulent open channel flow over a smooth horizontal wall in the presence of finite-size, heavy particles. The spherical particles have a diameter of approximately 7 wall units, a density of 1.7 times the fluid density and a solid volume fraction of 0.0005. The value of the Galileo number is set to 16.5, while the Shields parameter measures approximately 0.2. Under these conditions, the particles are predominantly located in the vicinity of the bottom wall, where they exhibit strong preferential concentration which we quantify by means of Voronoi analysis and by computing the particle-conditioned concentration field. As observed in previous studies with similar parameter values, the mean streamwise particle velocity is smaller than that of the fluid. We propose a new definition of the fluid velocity "seen" by finite-size particles based on an average over a spherical surface segment, from which we deduce in the present case that the particles are instantaneousl...
Kirkil, Gokhan
2016-11-01
The effect of the Solid Volume Fraction (SVF) on the flow structure within and past a circular array of surface-mounted cylinders that extends over 75% of the water depth, h is investigated using Detached Eddy Simulation (DES). This set up mimics the case of a submerged patch of rigid vegetation in a channel. The diameter of the cylinders in the array is d = 0.02D, where D is the diameter of the circular array. The channel Reynolds number is close to 20,000 and the Reynolds number defined with D is around 24,000. DES is conducted for SVF = 10% and 25%. It is found that as the SVF increases, fairly strong horseshoe vortex system forms around the upstream face of the vegetation patch, the strength of the separated shear layers on the sides of the vegetation patch increases and the length of the recirculation region behind the patch decreases. While an increase of the SVF results in a large increase of the turbulent kinetic energy in the wake, the opposite is observed within the porous vegetation patch.
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.
Directory of Open Access Journals (Sweden)
Willy Schuwarten Júnior
2013-10-01
Full Text Available A thermomechanical and a microstructure caracterization and a mathematical model of the evolution of the recrystallized volume fraction of ferrite in hot rolling in a Steckel mill have been carried out here. The proposed model is able to reasonably predict the observed in hot rolling, that is, there is 100% recrystallization of ferrite after roughing and partial recrystallization only after finishing
DEFF Research Database (Denmark)
Haarmark, Christian; Haase, Christine; Jensen, Maria Maj
2016-01-01
BACKGROUND: Estimation of left ventricular ejection fraction (LVEF) using equilibrium radionuclide angiography is an established method for assessment of left ventricular function. The purpose of this study was to establish normative data on left and right ventricular volumes and ejection fractio...
Directory of Open Access Journals (Sweden)
Choong Hoon Lee
2015-10-01
Full Text Available A computer simulation of a gas engine was performed to investigate the effects of the inert gas volume fraction in biogas on engine performance, specifically the engine torque and the brakespecific fuel consumption (BSFC using GT-Power®. The engine speeds used in the simulation were 900 and 1800 rpm, while the simulated engine loads were 25, 50, 75 and 100%. The volume fraction of the inert gas N2 in the biogas was varied from 20 to 80% with an interval of 10%. In a simulation of a naturally aspirated gas engine which is operated with an 80% volume fraction of N2 in biogas, the optimal air-fuel ratio in terms of the fuel economy and brake power generation was 3.5. In a simulation of a turbo intercooler gas engine operated with an 80% volume fraction of N2 in biogas, the optimal air-fuel ratios with regard to the fuel economy and brake power generation were 5.0 and 3.5, respectively.
Directory of Open Access Journals (Sweden)
Omid Ali Akbari
2015-11-01
Full Text Available This article aims to study the impact of ribs on flow parameters and laminar heat transfer of water–aluminum oxide nanofluid with different nanoparticle volume fractions in a three-dimensional rectangular microchannel. To this aim, compulsory convection heat transfer of water–aluminum oxide nanofluid in a rib-roughened microchannel has been numerically studied. The results of this simulation for rib-roughened three-dimensional microchannel have been evaluated in contrast to the smooth (unribbed three-dimensional microchannel with identical geometrical and heat–fluid boundary conditions. Numerical simulation is performed for different nanoparticle volume fractions for Reynolds numbers of 10 and 100. Cold fluid entering the microchannel is heated in order to apply constant flux to external surface of the microchannel walls and then leaves it. Given the results, the fluid has a higher heat transfer with a hot wall in surfaces with ribs rather than in smooth ones. As Reynolds number, number of ribs, and nanoparticle volume fractions increase, more temperature increase happens in fluid in exit intersection of the microchannel. By investigating Nusselt number and friction factor, it is observed that increase in nanoparticle volume fractions causes nanofluid heat transfer properties to have a higher heat transfer and friction factor compared to the base fluid used in cooling due to an increase in viscosity.
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Dańko R.
2016-12-01
Full Text Available The aim of the hereby paper is to present the developed model of determining the volume and surface porosity based on the main fraction of polifractional materials, its experimental verification and utilisation for the interpretation of effects accompanying the formation of a moulding sand apparent density, porosity and permeability in the blowing processes of the core and moulds technology.
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Y. Shinozuka
2010-08-01
Full Text Available We describe aerosol optical depth (AOD measured during the Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS experiment, conducted in North America in April and June–July 2008, focusing on vertical profiles, inter-comparison with correlative observations, fine-mode fraction and horizontal variability. The AOD spectra spanning 354–2139 nm measured with the 14-channel Ames Airborne Tracking Sunphotometer (AATS-14 are generally less wavelength-dependent below 2 km (499-nm Angstrom exponent 1.4 ± 0.3 than in 2–4 km (1.6–1.8 for Alaska in April 2008. Together with concurrent aerosol mass spectrometry and black carbon incandescence measurements, this corroborates the hypothesis that Arctic haze in these layers originates mainly from anthropogenic emission and biomass burning, respectively. The spectra are within 3%+0.02 of the vertical integral of local visible-light scattering and absorption for two thirds of the 55 vertical profiles examined. The horizontal structure of smoke plumes in central Canada in June and July 2008 explains most outliers. The differences in mid-visible Angstrom exponent are <0.10 for 63% of the profiles with 499-nm AOD>0.1. The retrieved fine-mode fraction of AOD is mostly between 0.7 and 1.0, and its root mean square difference from column-integral submicron fraction (measured with nephelometers, absorption photometers and an impactor is 0.12. These AOD measurements from the NASA P-3 aircraft, after compensation for below-aircraft light attenuation by vertical extrapolation, mostly fall within 0.02 of AERONET ground-based measurements for five overpass events. Evidently, the fresh local emission in Canada in June and July makes the horizontal distribution of AOD highly heterogeneous (standard deviation ~19% of the mean over 20 km and random (autocorrelation r=0.37 across 20 km, in contrast to long-range transport to Alaska in April (std~2%, r=0.95. The
Gas permeation measurement under defined humidity via constant volume/variable pressure method
Jan Roman, Pauls
2012-02-01
Many industrial gas separations in which membrane processes are feasible entail high water vapour contents, as in CO 2-separation from flue gas in carbon capture and storage (CCS), or in biogas/natural gas processing. Studying the effect of water vapour on gas permeability through polymeric membranes is essential for materials design and optimization of these membrane applications. In particular, for amine-based CO 2 selective facilitated transport membranes, water vapour is necessary for carrier-complex formation (Matsuyama et al., 1996; Deng and Hägg, 2010; Liu et al., 2008; Shishatskiy et al., 2010) [1-4]. But also conventional polymeric membrane materials can vary their permeation behaviour due to water-induced swelling (Potreck, 2009) [5]. Here we describe a simple approach to gas permeability measurement in the presence of water vapour, in the form of a modified constant volume/variable pressure method (pressure increase method). © 2011 Elsevier B.V.
Thosar, Archana; Patra, Amit; Bhattacharyya, Souvik
2008-07-01
Design of a nonlinear control system for a Variable Air Volume Air Conditioning (VAVAC) plant through feedback linearization is presented in this article. VAVAC systems attempt to reduce building energy consumption while maintaining the primary role of air conditioning. The temperature of the space is maintained at a constant level by establishing a balance between the cooling load generated in the space and the air supply delivered to meet the load. The dynamic model of a VAVAC plant is derived and formulated as a MIMO bilinear system. Feedback linearization is applied for decoupling and linearization of the nonlinear model. Simulation results for a laboratory scale plant are presented to demonstrate the potential of keeping comfort and maintaining energy optimal performance by this methodology. Results obtained with a conventional PI controller and a feedback linearizing controller are compared and the superiority of the proposed approach is clearly established.
Institute of Scientific and Technical Information of China (English)
LI Hua; WANG Mi; WU Ying-xiang; MA Yi-xin; WILLIAMS Richard
2005-01-01
This paper presents the use of a high performance dual-plane electrical resistance tomography (ERT) system and a local dual-sensor conductance probe to measure the vertical upward oil-in-water pipe flows in which the mean oil volume fraction is up to 23.1%.A sensitivity coefficient back-projection (SBP) algorithm was adopted to reconstruct the flow distributions and a cross correlation method was applied to obtain the oil velocity distributions. The oil volume fraction and velocity distributions obtained from both measurement techniques were compared and good agreement was found, which indicates that the ERT technique can be used to measure the low fraction oil-water flows. Finally, the factors affecting measurement precision were discussed.
On the Covering Fraction Variability in an EUV Mini-BAL Outflow from PG 1206+459
Muzahid, Sowgat; Charlton, Jane; Eracleous, Michael
2015-01-01
We report on the first detection of extreme-ultraviolet (EUV) absorption variability in the NeVIII 770,780 mini-broad absorption line (mini-BAL) in the spectrum of the quasar (QSO) PG 1206+459. The observed equivalent width (EW) of the NeVIII doublet show a ~4 sigma variation over a timescale of 2.8 months in the QSO's rest-frame. Both members of the NeVIII doublet exhibit non-black saturation, indicating partial coverage of the continuum source. An increase in the NeVIII covering fraction from f_c = 0.59\\pm0.05 to 0.72\\pm0.03 is observed over the same period. The NeVIII profiles are too highly saturated to be susceptible to changes in the ionization state of the absorbing gas. In fact, we do not observe any significant variation in the EW and/or column density after correcting the spectra for partial coverage. We, thus, propose transverse motions of the absorbing gas being the cause of the observed variability. Using a simple model of a transiting cloud we estimate a transverse speed of ~1800 km/s. For Keple...
Selbekk, R. S.; Tronnes, R. G.
2007-12-01
In the 50 km wide Icelandic rift zones rhyolite magma is generated by partial melting of hydrated metabasaltic crust, subsiding under the weight of the growing volcanic pile. This mechanism of silicic melt formation is indicated by the basalt-rhyolite bimodality and rhyolite O-isotope composition. The low 18/16O-isotope ratios of rift zone rhyolites trace the high-latitude meteoric water component of the subsiding hydrated basalts [1]. The rhyolites of the volcanic flank zones (VFZ), however, have generally as heavy oxygen as the associated alkaline to transitional basalts and intermediate volcanics [2,3]. The minor volcanic loading of the older, thicker and stronger VFZ crust is insufficient for significant subsidence, and less pronounced basalt-rhyolite bimodality combined with other geochemical features support silicic melt generation by fractional crystallization. An extreme case in Icelandic, as well as global, perspective is the rhyolite magma of the plinian eruption from the large VFZ-volcano, Oraefajokull, in 1362 AD [4]. Glass, mineral and bulk tephra analyses show no chemical variation exceeding the analytical precision for the entire erupted volume of 2 km3 DRE. This applies even to the glass shards from distant locations in Greenland, Norway and Ireland. The total phenocryst content is 0.5-1 wt percent, with oligoclase (An14 Ab81 Or5.5), fayalite (Fa99.7 Fo0.3) and hedenbergite (Wo44.7 En2.6 Fs52.7) constituting 50- 80, 10-25 and 10-25 percent of the total phenocrysts, respectively. The extreme mineral compositions (especially pure fayalite and hedenbergite) resemble those of the granophyres in the Skaergaard and Bushveld complexes and differ from all other investigated rhyolites. The advanced fractionation and homogenisation to form the erupted 2 km3 DRE rhyolite is petrogenetically challenging, and a parental magma chamber of 20-40 km3 seems like a conservative estimate. The time-scale of the historic magma chamber evolution under Oraefajokull is
Energy Technology Data Exchange (ETDEWEB)
Frey, H. Christopher [North Carolina State University, Raleigh, NC (United States); Rhodes, David S. [North Carolina State University, Raleigh, NC (United States)
1999-04-30
This is Volume 1 of a two-volume set of reports describing work conducted at North Carolina State University sponsored by Grant Number DE-FG05-95ER30250 by the U.S. Department of Energy. The title of the project is “Quantitative Analysis of Variability and Uncertainty in Acid Rain Assessments.” The work conducted under sponsorship of this grant pertains primarily to two main topics: (1) development of new methods for quantitative analysis of variability and uncertainty applicable to any type of model; and (2) analysis of variability and uncertainty in the performance, emissions, and cost of electric power plant combustion-based NOx control technologies. These two main topics are reported separately in Volumes 1 and 2.
Covey, Steven J.
1993-01-01
Notched unidirectional SCS-6/Ti-15-3 composite of three different fiber volume fractions (vf = 0.15, 0.37, and 0.41) was investigated for various room temperature microstructural and material properties including: fatigue crack initiation, fatigue crack growth, and fracture toughness. While the matrix hardness is similar for all fiber volume fractions, the fiber/matrix interfacial shear strength and matrix residual stress increases with fiber volume fraction. The composite fatigue crack initiation stress is shown to be matrix controlled and occurs when the net maximum matrix stress approaches the endurance limit stress of the matrix. A model is presented which includes residual stresses and presents the composite initiation stress as a function of fiber volume fraction. This model predicts a maximum composite initiation stress at vf approximately 0.15 which agrees with the experimental data. The applied composite stress levels were increased as necessary for continued crack growth. The applied Delta(K) values at crack arrest increase with fiber volume fraction by an amount better approximated using an energy based formulation rather than when scaled linear with modulus. After crack arrest, the crack growth rate exponents for vf37 and vf41 were much lower and toughness much higher, when compared to the unreinforced matrix, because of the bridged region which parades with the propagating fatigue crack. However, the vf15 material exhibited a higher crack growth rate exponent and lower toughness than the unreinforced matrix because once the bridged fibers nearest the crack mouth broke, the stress redistribution broke all bridged fibers, leaving an unbridged crack. Degraded, unbridged behavior is modeled using the residual stress state in the matrix ahead of the crack tip. Plastic zone sizes were directly measured using a metallographic technique and allow prediction of an effective matrix stress intensity which agrees with the fiber pressure model if residual stresses
Variable thickness transient ground-water flow model. Volume 3. Program listings
Energy Technology Data Exchange (ETDEWEB)
Reisenauer, A.E.
1979-12-01
The Assessment of Effectiveness of Geologic Isolation Systems (AEGIS) Program is developing and applying the methodology for assessing the far-field, long-term post-closure safety of deep geologic nuclear waste repositories. AEGIS is being performed by Pacific Northwest Laboratory (PNL) under contract with the Office of Nuclear Waste Isolation (OWNI) for the Department of Energy (DOE). One task within AEGIS is the development of methodology for analysis of the consequences (water pathway) from loss of repository containment as defined by various release scenarios. Analysis of the long-term, far-field consequences of release scenarios requires the application of numerical codes which simulate the hydrologic systems, model the transport of released radionuclides through the hydrologic systems to the biosphere, and, where applicable, assess the radiological dose to humans. Hydrologic and transport models are available at several levels of complexity or sophistication. Model selection and use are determined by the quantity and quality of input data. Model development under AEGIS and related programs provides three levels of hydrologic models, two levels of transport models, and one level of dose models (with several separate models). This is the third of 3 volumes of the description of the VTT (Variable Thickness Transient) Groundwater Hydrologic Model - second level (intermediate complexity) two-dimensional saturated groundwater flow.
Van Der Schijff, Hermanus P.
Variable air volume (VAV) air terminals are designed to save energy by reducing airflow into a given space based on occupancy and required load. Systems are typically designed to operate at peak load, however as load is reduced, performance is compromised due to inadequate throw. As a result, fans are installed to adjust for the losses, negating many of the energy savings. Additionally flow is vectored by the use of vanes, a basic passive type of flow control. An experimental investigation was performed to study the application of flow control on that of a HVAC diffuser using synthetic jets distributed evenly along the diffuser edge parallel to the flow field. The study was conducted on a 1:3 scale typical office space (150 ft2), which included a simulated scale HVAC system supplied by compressed air. Two different jet blowing ratios were investigated for system loads of 60% and 90%. The flow field was established using hot wire anemometry and Particle Image Velocimetry (PIV). This study demonstrates the effectiveness of synthetic jet based active flow control at controlling airflow, showing ability to affect throw parameters for changing flow rates within the test chamber. Vectoring of up to 20% and improvement in jet spread of 200% was demonstrated. The use of such devices has the potential to improve air quality and air distribution in building while simultaneously lowering energy demands of HVAC systems.
Wear Behavior of Al-Mg2Si Cast In-situ Composite: Effect of Mg2Si Different Volume Fractions
Ghiasinejad, J.; Emamy, M.; Ghorbani, M. R.; Malekan, A.
2010-06-01
Al-Mg2Si in situ composites are great candidates for automobile brake discs due to their low density, reasonably high young's modulus and low thermal expansion coefficient. Thus, understanding wear properties of this composite is of a great importance. In this study wear behavior of an in-situ Al-Mg2Si composite, prepared from a simple casting route, has been investigated using a pin-on-disc configuration concerning the effect of Mg2Si volume fractions, 15, 20 and 25% respectively. It was found that the weight loss increases with increase in reinforce volume fraction which can be due to a coarse morphology of primary Mg2Si particles. It was found that the variations of weight loss with sliding distance comprise different regimes of which the mechanisms are discussed.
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Schwab, K.; Brack, W. [UFZ - Helmholtz Centre or Environmental Research, Leipzig (Germany). Dept. of Effect-Directed Analysis
2007-06-15
Background, Aim and Scope: Effect-directed analysis (EDA) is a powerful tool for the identification of key toxicants in complex environmental samples. In most cases, EDA is based on total extraction of organic contaminants leading to an erroneous prioritization with regard to hazard and risk. Bioaccessibility-directed extraction aims to discriminate between contaminants that take part in partitioning between sediment and biota in a relevant time frame and those that are enclosed in structures, that do not allow rapid desorption. Standard protocols of targeted extraction of rapidly desorbing, and thus bioaccessible fraction using TENAX {sup registered} are based only on small amounts of sediment. In order to get sufficient amounts of extracts for subsequent biotesting, fractionation, and structure elucidation a large volume extraction technique needs to be developed applying one selected extraction time and excluding toxic procedural blanks. Materials and Methods: Desorption behaviour of sediment contaminants was determined by a consecutive solid-solid extraction of sediment using TENAX {sup registered} fitting a tri-compartment model on experimental data. Time needed to remove the rapidly desorbing fraction trap was calculated to select a fixed extraction time for single extraction procedures. Up-scaling by about a factor of 100 provided a large volume extraction technique for EDA. Reproducibility and comparability to small volume approach were proved. Blanks of respective TENAX {sup registered} mass were investigated using Scenedesmus vacuolatus and Artemia salina as test organisms. Results: Desorption kinetics showed that 12 to 30 % of sediment associated pollutants are available for rapid desorption. t{sub r}ap is compound dependent and covers a range of 2 to 18 h. On that basis a fixed extraction time of 24 h was selected. Validation of large volume approach was done by the means of comparison to small method and reproducibility. The large volume showed a good
Directory of Open Access Journals (Sweden)
Kouhei Kamiya
Full Text Available PURPOSE: Previous studies suggest that compression and stretching of the corticospinal tract (CST potentially cause treatable gait disturbance in patients with idiopathic normal pressure hydrocephalus (iNPH. Measurement of axon diameter with diffusion MRI has recently been used to investigate microstructural alterations in neurological diseases. In this study, we investigated alterations in the axon diameter and intra-axonal fraction of the CST in iNPH by q-space imaging (QSI analysis. METHODS: Nineteen patients with iNPH and 10 age-matched controls were recruited. QSI data were obtained with a 3-T system by using a single-shot echo planar imaging sequence with the diffusion gradient applied parallel to the antero-posterior axis. By using a two-component low-q fit model, the root mean square displacements of intra-axonal space ( = axon diameter and intra-axonal volume fraction of the CST were calculated at the levels of the internal capsule and body of the lateral ventricle, respectively. RESULTS: Wilcoxon's rank-sum test revealed a significant increase in CST intra-axonal volume fraction at the paraventricular level in patients (p<0.001, whereas no significant difference was observed in the axon diameter. At the level of the internal capsule, neither axon diameter nor intra-axonal volume fraction differed significantly between the two groups. CONCLUSION: Our results suggest that in patients with iNPH, the CST does not undergo irreversible axonal damage but is rather compressed and/or stretched owing to pressure from the enlarged ventricle. These analyses of axon diameter and intra-axonal fraction yield insights into microstructural alterations of the CST in iNPH.
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Amrollahi, A; Hamidi, A A [Faculty of Engineering, University of Teheran, PO Box 11365-4563, Teheran (Iran, Islamic Republic of); Rashidi, A M [Gas Division of Research Institute of Petroleum Industry, PO Box 18745-4163, Tehran (Iran, Islamic Republic of)], E-mail: rashidiam@ripi.ir
2008-08-06
In this investigation, nanofluids of carbon nanotubes are prepared and the thermal conductivity and volumetric heat capacity of these fluids are measured using a thin layer technique as a function of time of ultrasonication, temperature, and volume fraction. It has been observed that after using the ultrasonic disrupter, the size of agglomerated particles and number of primary particles in a particle cluster was significantly decreased and that the thermal conductivity increased with elapsed ultrasonication time. The clustering of carbon nanotubes was also confirmed microscopically. The strong dependence of the effective thermal conductivity on temperature and volume fraction of nanofluids was attributed to Brownian motion and the interparticle potential, which influences the particle motion. The effect of temperature will become much more evident with an increase in the volume fraction and the agglomeration of the nanoparticles, as observed experimentally. The data obtained from this work have been compared with those of other studies and also with mathematical models at present proven for suspensions. Using a 2.5% volumetric concentration of carbon nanotubes resulted in a 20% increase in the thermal conductivity of the base fluid (ethylene glycol).The volumetric heat capacity also showed a pronounced increase with respect to that of the pure base fluid.
Amrollahi, A; Hamidi, A A; Rashidi, A M
2008-08-06
In this investigation, nanofluids of carbon nanotubes are prepared and the thermal conductivity and volumetric heat capacity of these fluids are measured using a thin layer technique as a function of time of ultrasonication, temperature, and volume fraction. It has been observed that after using the ultrasonic disrupter, the size of agglomerated particles and number of primary particles in a particle cluster was significantly decreased and that the thermal conductivity increased with elapsed ultrasonication time. The clustering of carbon nanotubes was also confirmed microscopically. The strong dependence of the effective thermal conductivity on temperature and volume fraction of nanofluids was attributed to Brownian motion and the interparticle potential, which influences the particle motion. The effect of temperature will become much more evident with an increase in the volume fraction and the agglomeration of the nanoparticles, as observed experimentally. The data obtained from this work have been compared with those of other studies and also with mathematical models at present proven for suspensions. Using a 2.5% volumetric concentration of carbon nanotubes resulted in a 20% increase in the thermal conductivity of the base fluid (ethylene glycol).The volumetric heat capacity also showed a pronounced increase with respect to that of the pure base fluid.
Directory of Open Access Journals (Sweden)
H. Shokrollahi
2016-03-01
Full Text Available The purpose of this work is to investigate the effects of the volume fraction and bimodal distribution of solid particles on the compression and tension behavior of the Co-ferrite-based magneto-rheological fluids (MRFs containing silicon oil as a carrier. Hence, Co-ferrite particles (CoFe2O4 with two various sizes were synthesized by the chemical co-precipitation method and mixed so as to prepare the bimodal MRF. The X-Ray Diffraction (XRD analysis, Fourier Transform Infrared Spectroscopy (FTIR, Laser Particle Size Analysis (LPSA and Vibrating Sample Magnetometer (VSM were conducted to examine the structural and magnetic properties, respectively. The results indicated that the increase of the volume fraction has a direct increasing influence on the values of the compression and tension strengths of fluids. In addition, the compression and tension strengths of the mixed MRF sample (1.274 and 0.647 MPa containing 60 and 550 nm samples were higher than those of the MRF sample with the same volume fraction and uniform particle size of 550 nm.
Montandon, L. M.; Small, E.
2008-12-01
The green vegetation fraction (Fg) is an important climate and hydrologic model parameter. The commonly- used Fg model is a simple linear mixing of two NDVI end-members: bare soil NDVI (NDVIo) and full vegetation NDVI (NDVI∞). NDVI∞ is generally set as a percentile of the historical maximum NDVI for each land cover. This approach works well for areas where Fg reaches full cover (100%). Because many biomes do not reach Fg=0, however, NDVIo is often determined as a single invariant value for all land cover types. In general, it is selected among the lowest NDVI observed over bare or desert areas, yielding NDVIo close to zero. There are two issues with this approach: large-scale variability of soil NDVI is ignored and observations on a wide range of soils show that soil NDVI is often larger. Here we introduce and test two new approaches to compute Fg that takes into account the spatial variability of soil NDVI. The first approach uses a global soil NDVI database and time series of MODIS NDVI data over the conterminous United States to constrain possible soil NDVI values over each pixel. Fg is computed using a subset of the soils database that respects the linear mixing model condition NDVIo≤NDVIh, where NDVIh is the pixel historical minimum. The second approach uses an empirical soil NDVI model that combines information of soil organic matter content and texture to infer soil NDVI. The U.S. General Soil Map (STATSGO2) database is used as input for spatial soil properties. Using in situ measurements of soil NDVI from sites that span a range of land cover types, we test both models and compare their performance to the standard Fg model. We show that our models adjust the temporal Fg estimates by 40-90% depending on the land cover type and amplitude of the seasonal NDVI signal. Using MODIS NDVI and soil maps over the conterminous U.S., we also study the spatial distribution of Fg adjustments in February and June 2008. We show that the standard Fg method
Newa, Madhuri; Lam, Michael; Bhandari, Krishna Hari; Xu, Biwen; Doschak, Michael R
2014-01-06
A single chain Fraction variable (scFv) employs antibody-like target recognition specificity. Osteoclasts, responsible for bone resorption, express Receptor Activator of Nuclear factor Kappa B (RANK) receptors. This study aimed to express, characterize, and evaluate scFv against RANK receptors that may serve as a platform to target osteoclasts. Using phage display technology, scFv against RANK receptor was expressed and characterized by DNA sequencing, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), matrix-assisted laser desorption-ionization time-of-flight (MALDI TOF), enzyme-linked immunosorbent assay (ELISA), Western blot, and immunocytochemistry. The potential for cytotoxicity was evaluated using an MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide) assay, and its cross reactivity was evaluated using ELISA. Osteoclast-like cells were generated from RAW 264.7 cells, and the osteoclast targeting ability of scFv was evaluated using immunocytochemistry. ScFv's antiresorptive efficacy was studied using a tartrate-resistant acid phosphatase (TRAP) assay and resorption assay. Anti-RANK scFv was successfully expressed and characterized. No cross reactivity with other tumor necrosis factor receptor (TNFR) members and no cytotoxic effect on a non-RANK bearing cell line were observed. It showed specificity toward a RANK receptor and an inhibitory effect on osteoclast activity. With the increase in development trends for biologics as therapeutics and growing knowledge on the importance of osteoclast targeted therapy, this study may provide a drug delivery strategy to target osteoclasts, thereby leading to a promising therapy for resorptive bone diseases.
Müller, Hans-Peter; Unrath, Alexander; Riecker, Axel; Pinkhardt, Elmar H; Ludolph, Albert C; Kassubek, Jan
2009-04-01
Diffusion tensor imaging (DTI) provides comprehensive information about quantitative diffusion and connectivity in the human brain. Transformation into stereotactic standard space is a prerequisite for group studies and requires thorough data processing to preserve directional inter-dependencies. The objective of the present study was to optimize technical approaches for this preservation of quantitative and directional information during spatial normalization in data analyses at the group level. Different averaging methods for mean diffusion-weighted images containing DTI information were compared, i.e., region of interest-based fractional anisotropy (FA) mapping, fiber tracking (FT) and corresponding tractwise FA statistics (TFAS). The novel technique of intersubject FT that takes into account directional information of single data sets during the FT process was compared to standard FT techniques. Application of the methods was shown in the comparison of normal subjects and subjects with defined white matter pathology (alterations of the corpus callosum). Fiber tracking was applied to averaged data sets and showed similar results compared with FT on single subject data. The application of TFAS to averaged data showed averaged FA values around 0.4 for normal controls. The values were in the range of the standard deviation for averaged FA values for TFAS applied to single subject data. These results were independent of the applied averaging technique. A significant reduction of the averaged FA values was found in comparison to TFAS applied to data from subjects with defined white matter pathology (FA around 0.2). The applicability of FT techniques in the analysis of different subjects at the group level was demonstrated. Group comparisons as well as FT on group averaged data were shown to be feasible. The objective of this work was to identify the most appropriate method for intersubject averaging and group comparison which incorporates intersubject variability of
Directory of Open Access Journals (Sweden)
A. Pantet
2010-01-01
Full Text Available Coastal erosion results from a combination of various factors, both natural and humaninduced, which have different time and space patterns. In addition, uncertainties still remain about the interactions of the forcing agents, as well as on the significance of non-local causes of erosion. We focused about the surface sediments in the Marennes Oléron bay, after a general description of the site that has many various activities. The superficial sediments show a mechanical behavior, mainly depends on the fine fraction for a composition that contains up to 60% of sandy material. Fine sediments fraction has a typical yield stress depending naturally of concentration or water content. This yield could be modified slightly or significantly by adding silt or sand. As a result, the rheological measurement sensitivity allows us to characterize five typical sediments that correlate with solid fraction and fine fraction.
Energy Technology Data Exchange (ETDEWEB)
Hou, Y; Aileen, C; Kozono, D; Killoran, J; Wagar, M; Lee, S; Hacker, F; Aerts, H; Lewis, J; Mak, R [Brigham and Women’s Hospital, Boston, MA (United States)
2015-06-15
Purpose: Quantification of volume changes on CBCT during SBRT for NSCLC may provide a useful radiological marker for radiation response and adaptive treatment planning, but the reproducibility of CBCT volume delineation is a concern. This study is to quantify inter-scan/inter-observer variability in tumor volume delineation on CBCT. Methods: Twenty earlystage (stage I and II) NSCLC patients were included in this analysis. All patients were treated with SBRT with a median dose of 54 Gy in 3 to 5 fractions. Two physicians independently manually contoured the primary gross tumor volume on CBCTs taken immediately before SBRT treatment (Pre) and after the same SBRT treatment (Post). Absolute volume differences (AVD) were calculated between the Pre and Post CBCTs for a given treatment to quantify inter-scan variability, and then between the two observers for a given CBCT to quantify inter-observer variability. AVD was also normalized with respect to average volume to obtain relative volume differences (RVD). Bland-Altman approach was used to evaluate variability. All statistics were calculated with SAS version 9.4. Results: The 95% limit of agreement (mean ± 2SD) on AVD and RVD measurements between Pre and Post scans were −0.32cc to 0.32cc and −0.5% to 0.5% versus −1.9 cc to 1.8 cc and −15.9% to 15.3% for the two observers respectively. The 95% limit of agreement of AVD and RVD between the two observers were −3.3 cc to 2.3 cc and −42.4% to 28.2% respectively. The greatest variability in inter-scan RVD was observed with very small tumors (< 5 cc). Conclusion: Inter-scan variability in RVD is greatest with small tumors. Inter-observer variability was larger than inter-scan variability. The 95% limit of agreement for inter-observer and inter-scan variability (∼15–30%) helps define a threshold for clinically meaningful change in tumor volume to assess SBRT response, with larger thresholds needed for very small tumors. Part of the work was funded by a Kaye
Sreerama, Yadahally N; Sashikala, Vadakkoot B; Pratape, Vishwas M
2010-07-28
Seed coat, cotyledon and embryonic axe fractions of chickpea (Cicer arietinum L.) and horse gram (Macrotyloma uniflorum L.) were evaluated for their phenolic composition in relation to antioxidant activities. Compositional analysis of phenolics by HPLC revealed a wide variation in the distribution of flavonols, isoflavones, phenolic acids and anthocyanins among these legume fractions. Although cotyledon fractions of both the legumes were rich in phenolic acids, the concentrations of flavonols such as quercetin, kaempferol, and myricetin were significantly (p chickpea, it was present exclusively in the embryonic axe fraction of horse gram at levels greater than daidzein. Furthermore, cyanidin, petunidin, and delphinidin were detected in seed coat and embryonic axe fractions but not in cotyledons. In addition to these three anthocyanins, malvidin was found only in the horse gram seed coat fraction. Seed coat fractions having higher total phenolic indexes were found to be the most active 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavengers (IC(50) 13.1 to 18.6 microg/mL) followed by embryonic axe and cotyledon fractions (IC(50) 15.4 to 34.2 microg/mL). Hydrogen peroxide (H(2)O(2)) scavenging capacities of cotyledons, embryonic axe and seed coats were 12.3, 34.1 and 78.6% for chickpea and 15.1, 56.8 and 92.6% for horse gram, respectively. The multiple antioxidant activity of horse gram and chickpea fractions was evident, as they also possessed reducing power and ferrous ion-chelating potency. These results contributed to the understanding of the relationships between major phenolic compounds and antioxidant activities of legumes and provided useful information for effective utilization of legume-milled fractions as functional food ingredients for promoting health.
Grier, Thomas J; Converse, Lorie M; Rekkerth, Donna J; Renahan, Kevin E
2016-05-01
Current summaries of effective maintenance dose ranges for subcutaneous immunotherapy (SCIT) are based on administration of 0.5-mL volumes. Extract formulations delivering equivalent dose ranges for practices using different injection volumes have not been reported, and calculation of the final glycerin concentrations in these solutions remains an inconvenient and repetitive process. To create math-free guides for allergen doses and glycerin concentrations that identify the extract concentrate volumes required to deliver doses within the ranges cited in the 2011 immunotherapy practice parameters for clinicians using 5.0-mL maintenance vials and injection volumes ranging from 0.2 to 1.0 mL. Algebraic calculations were performed to determine the specific combinations of extract concentrate strengths, volumes of these products in patient vaccines, and injection volumes needed for administration of target allergen doses spanning the current SCIT practice parameter recommendations. For each product or group (nonstandardized extracts), tables were constructed to define the allergen doses provided by various combinations of extract concentrate volumes and injection volumes. The values within the effective dose ranges for each product were highlighted to facilitate comparisons of specific conditions relevant to allergy specialists. Glycerin tables were also created to permit convenient assessments of the final concentrations of this stabilizer in patient prescriptions. SCIT dosing and glycerin tables are useful tools to assist allergists with practice decisions that involve variable patient formulas and injection volumes and can help identify suitable conditions for treatment of patients presenting with diverse allergen sensitivities and specificity profiles. Copyright © 2016 American College of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.
Genovesi, Domenico; Cèfaro, Giampiero Ausili; Vinciguerra, Annamaria; Augurio, Antonietta; Di Tommaso, Monica; Marchese, Rita; Ricardi, Umberto; Filippi, Andrea Riccardo; Girinsky, Theodore; Di Biagio, Katiuscia; Belfiglio, Maurizio; Barbieri, Enza; Valentini, Vincenzo
2011-06-01
To determine interobserver variability in clinical target volume (CTV) of supra-diaphragmatic Hodgkin's lymphoma. At the 2008 AIRO (Italian Society of Radiation Oncology) Meeting, the Radiation Oncology Department of Chieti proposed a multi-institutional contouring dummy-run of two cases of early stage supra-diaphragmatic Hodgkin's lymphoma after chemotherapy. Clinical history, diagnostics, and planning CT imaging were available on Chieti's radiotherapy website (www.radioterapia.unich.it). Participating centers were requested to delineate the CTV and submit it to the coordinating center. To quantify interobserver variability of CTV delineations, the total volume, craniocaudal, laterolateral, and anteroposterior diameters were calculated. A total of 18 institutions for case A and 15 institutions for case B submitted the targets. Case A presented significant variability in total volume (range: 74.1-1,157.1 cc), craniocaudal (range: 6.5-22.5 cm; median: 16.25 cm), anteroposterior (range: 5.04-14.82 cm; median: 10.28 cm), and laterolateral diameters (range: 8.23-22.88 cm; median: 15.5 cm). Mean CTV was 464.8 cc (standard deviation: 280.5 cc). Case B presented significant variability in total volume (range: 341.8-1,662 cc), cranio-caudal (range: 8.0-28.5 cm; median: 23 cm), anteroposterior (range: 7.9-1.8 cm; median: 11.1 cm), and laterolateral diameters (range: 12.9-24.0 cm; median: 18.8 cm). Mean CTV was 926.0 cc (standard deviation: 445.7 cc). This significant variability confirms the need to apply specific guidelines to improve contouring uniformity in Hodgkin's lymphoma.
Wilkinson, Ashley S; Flanagan, Bernadine M; Pierson, Jean-Thomas; Hewavitharana, Amitha K; Dietzgen, Ralf G; Shaw, P Nicholas; Roberts-Thomson, Sarah J; Monteith, Gregory R; Gidley, Michael J
2011-01-01
Mangos are a source of bioactive compounds with potential health promoting activity. Biological activities associated with mango fractions were assessed in cell-based assays to develop effective extraction and fractionation methodologies and to define sources of variability. Two techniques were developed for extraction and fractionation of mango fruit peel and flesh. Liquid chromatography-mass spectrometry (LC-MS) was used to assess compositional differences between mango fractions in flesh extracts. Many of the extracts were effective in inhibiting the proliferation of human breast cancer cells in vitro. All fractions showed bioactivity in PPAR activation assays, but quantitative responses showed marked fruit-to-fruit variability, highlighting the need to bulk fruit prior to extraction for activity-guided fractionation of bioactive components. This study also suggests that combinations of diverse molecular components may be responsible for cell-level bioactivities from mango fractions, and that purification and activity profiling of individual components may be difficult to relate to whole fruit effects. Practical Application: Although the health benefits of fruits are strongly indicated from studies of diet and disease, it is not known what role individual fruit types can play, particularly for tropical fruits. This study shows that there is a diversity of potentially beneficial bioactivities within the flesh and peel of mango fruit, although fruit-to-fruit variation can be large. The results add to the evidence that the food approach of eating all components of fruits is likely to be more beneficial to health than consuming refined extracts, as the purification process would inevitably remove components with beneficial bioactivities.
DEFF Research Database (Denmark)
Boas, M.; Hegedus, L.; Feldt-Rasmussen, U.;
2009-01-01
. DESIGN AND PARTICIPANTS: A total of 859 prepubertal euthyroid Danish children aged 4-9 yr underwent a thorough clinical investigation, including anthropometrical measurements and determination of TSH, thyroid hormones, autoantibodies, urinary iodine excretion, and thyroid volume (TV) by ultrasound...... significantly associated with TV. Family history of thyroid disease and presence of incidental abnormal ultrasound findings were also positively associated with TV (P = 0.025 and 0.022, respectively). CONCLUSIONS: In our cohort of prepubertal Danish children, the GH/IGF-I-axis was positively correlated......CONTEXT AND OBJECTIVE: Few studies have focused on the interrelation between thyroid size, anthropometric variables, and IGF-I in adults, but such data are lacking for children. We have investigated thyroid gland volume and several hormonal and anthropometric variables in prepubertal children...
Fu, Q; Mi, W D; Zhang, H
2012-02-01
Respiration variation in arterial pulse pressure (ΔPP) and pulse oximetry plethysmographic waveform amplitude (ΔPOP) are accurate predictors of fluid responsiveness in mechanically ventilated patients. We hypothesized that stroke volume variation (SVV) and pleth variability index (PVI) can predict fluid responsiveness in mechanically ventilated patients during major surgical procedures in Hans Chinese. This prospective study consisted of fifty-five Hans Chinese patients undergoing resection of primary retroperitoneal tumors (PRPT). During the surgical procedures, hemodynamic data [central venous pressure (CVP), cardiac index (CI), stroke volume index (SVI), SVV, and PVI] were recorded before and after volume expansion (VE) (8 ml•kg-1 of 6% hydroxyethyl starch 130/0.4). Fluid responsiveness was defined as an increase in SVI ≥ 10% after VE. Four patients were excluded from analysis for arrhythmia or obvious hemorrhage during VE. Baseline SVV correlated well with baseline PVI and the changes in SVV was correlated with the changes in PVI (p Chinese.
Patterson, R P; Zhang, J; Mason, L I; Jerosch-Herold, M
2001-02-01
A study was conducted using the Sheffield electrical impedance tomography (EIT) portable system DAS-01 P to determine the change in the cardiac image with electrode position, lung volume and body position. Sixteen electrodes were positioned in three transverse planes around the thorax at the level of the second intercostal space, at the level of the xiphisternal joint, and midway between upper and lower locations. Data were collected at each electrode level with the breath held at end expiration and after inspiring 0.5, 1 and 1.5 l of air with the subject in both the supine and sitting position. These data were analysed using a Matlab developed program that calculates the average resistivity change in the cardiac region from automatically determined borders. Results show significant individual variability with electrode position and air volume. The middle electrode most consistently shows an increase in impedance in the region of the heart during systole. In some subjects the change in the ventricular-volume-like curve showed a greater than 50% change as a function of lung volume. The pattern of variability with electrode position was not consistent among subjects. In one subject MRI images were obtained to compare actual structures with those seen in the EIT image. The results suggest that using these electrode locations reliable and consistent data, which could be used in clinical applications, cannot be obtained.
Samus', N. N.; Goranskii, V. P.; Durlevich, O. V.; Zharova, A. V.; Kazarovets, E. V.; Kireeva, N. N.; Pastukhova, E. N.; Williams, D. B.; Hazen, M. L.
2003-07-01
We present a new electronic version of the second volume of the fourth edition of the General Catalogue of Variable Stars (GCVS), which contains data on 13 480 variable stars in the constellations Cygnus-Orion (the order of constellations in the Catalogue follows the Latin alphabet). The new version takes into account the Name Lists of Variable Stars from no. 67 to 76 for the same constellations. The main distinctive feature of the new version is that it contains improved equatorial J2000.0 coordinates for 13 446 stars (including those for 5052 stars with an allowance made for proper motions), based on the identifications with positional catalogs using finding charts, as well as on our new measurements. We searched for a number of stars on original plates from the collections of several observatories and using digital sky survey images. The new version also includes a file of remarks to the second and third GCVS volumes. Apart from a complete update of the positional information, we took into account several corrections that were found to be necessary after the publication of the second GCVS volume (1985). We present a list of references to new Internet resources.
Vassiliou, Vassilios S; Wassilew, Katharina; Cameron, Donnie; Heng, Ee Ling; Nyktari, Evangelia; Asimakopoulos, George; de Souza, Anthony; Giri, Shivraman; Pierce, Iain; Jabbour, Andrew; Firmin, David; Frenneaux, Michael; Gatehouse, Peter; Pennell, Dudley J; Prasad, Sanjay K
2017-06-12
Our objectives involved identifying whether repeated averaging in basal and mid left ventricular myocardial levels improves precision and correlation with collagen volume fraction for 11 heartbeat MOLLI T 1 mapping versus assessment at a single ventricular level. For assessment of T 1 mapping precision, a cohort of 15 healthy volunteers underwent two CMR scans on separate days using an 11 heartbeat MOLLI with a 5(3)3 beat scheme to measure native T 1 and a 4(1)3(1)2 beat post-contrast scheme to measure post-contrast T 1, allowing calculation of partition coefficient and ECV. To assess correlation of T 1 mapping with collagen volume fraction, a separate cohort of ten aortic stenosis patients scheduled to undergo surgery underwent one CMR scan with this 11 heartbeat MOLLI scheme, followed by intraoperative tru-cut myocardial biopsy. Six models of myocardial diffuse fibrosis assessment were established with incremental inclusion of imaging by averaging of the basal and mid-myocardial left ventricular levels, and each model was assessed for precision and correlation with collagen volume fraction. A model using 11 heart beat MOLLI imaging of two basal and two mid ventricular level averaged T 1 maps provided improved precision (Intraclass correlation 0.93 vs 0.84) and correlation with histology (R (2) = 0.83 vs 0.36) for diffuse fibrosis compared to a single mid-ventricular level alone. ECV was more precise and correlated better than native T 1 mapping. T 1 mapping sequences with repeated averaging could be considered for applications of 11 heartbeat MOLLI, especially when small changes in native T 1/ECV might affect clinical management.
Directory of Open Access Journals (Sweden)
A. H. Meysami
2017-01-01
Full Text Available In this paper, the effect of volume fraction of single-walled carbon nanotubes on natural frequencies of polymer composite cone-shaped shells made from Poly(Methyl Methacrylate (PMMA is studied. In order to determine the characterization of materials reinforced with nanoparticles, the molecular dynamics and mixture rule has been used. The motion equations of composite shell based on the classical thin shells theory using Hamilton’s principle are obtained. Then, using the Ritz method, approximate analytical solution of the natural frequency is presented. Results indicate that the nanotubes have a noticeable effect on the natural frequencies.
Gărăjeu, M.; Suquet, P.
2007-04-01
Composite materials often exhibit local fluctuations in the volume fraction of their individual constituents. This paper studies the influence of such small fluctuations on the effective properties of composites. A general asymptotic expansion of these properties in terms of powers of the amplitude of the fluctuations is given first. Then, this general result is applied to porous materials. As is well-known, the effective yield surface of ductile voided materials is accurately described by Gurson's criterion. Suitable extensions for viscoplastic solids have also been proposed. The question addressed in the present study pertains to nonuniform distributions of voids in a typical volume element or in other words to the presence of matrix-rich and pore-rich zones in the material. It is shown numerically and analytically that such deviations from a uniform distribution result in a weakening of the macroscopic carrying capacity of the material.
Omari, Taher I; Dejaeger, Eddy; Tack, Jan; Van Beckevoort, Dirk; Rommel, Nathalie
2013-06-01
Automated impedance manometry (AIM) analysis measures swallow variables defining bolus timing, pressure, contractile vigour, and bolus presence, which are combined to derive a swallow risk index (SRI) correlating with aspiration. In a heterogeneous cohort of dysphagia patients, we assessed the impact of bolus volume and viscosity on AIM variables. We studied 40 patients (average age = 46 years). Swallowing of boluses was recorded with manometry, impedance, and videofluoroscopy. AIMplot software was used to derive functional variables: peak pressure (PeakP), pressure at nadir impedance (PNadImp), time from nadir impedance to peak pressure (TNadImp-PeakP), the interval of impedance drop in the distal pharynx (flow interval, FI), upper oesophageal sphincter (UES) relaxation interval (UES RI), nadir UES pressure (Nad UESP), UES intrabolus pressure (UES IBP), and UES resistance. The SRI was derived using the formula SRI = (FI * PNadImp)/(PeakP * (TNadImp-PeakP + 1)) * 100. A total of 173 liquid, 44 semisolid, and 33 solid boluses were analysed. The SRI was elevated in relation to aspiration. PeakP increased with volume. SRI was not significantly altered by bolus volume. PNadImp, UES IBP, and UES resistance increased with viscosity. SRI was lower with increased viscosity. In patients with dysphagia, the SRI is elevated in relation to aspiration, reduced by bolus viscosity, and not affected by bolus volume. These data provide evidence that pharyngeal AIM analysis may have clinical utility for assessing deglutitive aspiration risk to liquid boluses.
Pokhrel, Samir; Sikka, D. R.
2013-07-01
Level 3 (3A25) TRMM Precipitation Radar (PR) data are used for 13 years period (1998-2010) to prepare climatology of TRMM PR derived near surface rain (Total rain) and rain fractions for the 4-months duration of Indian Summer Monsoon season (June-September) as well as for individual months. It is found that the total rain is contributed mostly (99 %) by two rain fractions i.e. stratiform and convective rain fractions for the season as well as on the monthly basis. It is also found that total rain estimates by PR are about 65 % of the gauge measured rain over continental India as well as on sub-regional basis. Inter-annual variability of TRMM-PR rain estimates for India mainland and its sub-regions as well as over the neighboring oceanic regions, in terms of coefficient of variability (CV) is discussed. The heaviest rain region over north Bay of Bengal (BoB) is found to have the lowest CV. Another sub-region of low CV lies over the eastern equatorial Indian ocean (EEIO). The CVs of total rain as well as its two major constituents are found to be higher on monthly basis compared to seasonal basis. Existence of a well known dipole between the EEIO and the north BoB is well recognized in PR data also. Significant variation in PR rainfall is found over continental India between excess and deficit monsoon seasons as well as between excess and deficit rainfall months of July and August. Examination of rainfall fractions between the BoB and Central India on year to year basis shows that compensation in rainfall fractions exists on monthly scale on both the regions. Also on the seasonal and monthly scales, compensation is observed in extreme monsoon seasons between the two regions. However, much less compensation is observed between the north BoB and EEIO belts in extreme rain months. This leads to speculation that the deficit and excess seasons over India may result from slight shift of the rainfall from Central India to the neighboring oceanic regions of north Bo
DEFF Research Database (Denmark)
Haedersdal, C; Pedersen, F H; Svendsen, Jesper Hastrup
1992-01-01
The present study compares the variables assessed by standard exercise test with the left ventricular ejection fraction (LVEF) measured by multigated radionuclide angiocardiography (MUGA) in 77 patients early after myocardial infarction. The exercise test and MUGA were performed within two weeks...... after the myocardial infarction. A significant correlation (Spearman's correlation coefficient rs, p less than 0.05) was found between LVEF at rest and the following variables assessed at exercise test: 1) the heart rate at rest, 2) rise in heart rate, 3) ratio between maximal heart rate and heart rate...... at rest, 4) rise in systolic blood pressure, 5) rate pressure product at rest, 6) rise in rate pressure product, 7) ratio (rHR) between maximal rate pressure product and rate pressure product at rest, 8) total exercise time. The heart rate was corrected for effects caused by age (heart index (HR...
DEFF Research Database (Denmark)
Haedersdal, C; Pedersen, F H; Svendsen, Jesper Hastrup
1992-01-01
at rest, 4) rise in systolic blood pressure, 5) rate pressure product at rest, 6) rise in rate pressure product, 7) ratio (rHR) between maximal rate pressure product and rate pressure product at rest, 8) total exercise time. The heart rate was corrected for effects caused by age (heart index (HR...... after the myocardial infarction. A significant correlation (Spearman's correlation coefficient rs, p less than 0.05) was found between LVEF at rest and the following variables assessed at exercise test: 1) the heart rate at rest, 2) rise in heart rate, 3) ratio between maximal heart rate and heart rate......The present study compares the variables assessed by standard exercise test with the left ventricular ejection fraction (LVEF) measured by multigated radionuclide angiocardiography (MUGA) in 77 patients early after myocardial infarction. The exercise test and MUGA were performed within two weeks...
Sky catalogue 2000.0. Volume 2: Double stars, variable stars and nonstellar objects.
Hirshfeld, A.; Sinnott, R. W.
This is a re-issue of a book first published in 1985 (see Abstr. 39.002.019). This is a standard reference work for telescope users which gives positional and other data for galaxies, double and variable stars, and star clusters. It includes tables on 20,000 objects. Comprehensive treatment is given for each object: position for epoch 2000.0, magnitudes in the UBV photometric system, color index, surface brightness and Hubble classification for galaxies. Contents: Glossary of selected astronomical names. Index to letter names of variable stars. Double and multiple stars. Visual binary stars. Spectroscopic binary stars. Variable stars. Suspected variable stars. Open clusters. Open cluster cross index. Globular clusters. Bright nebulae. Dark nebulae. Planetary nebulae. Galaxies. Quasi-stellar objects (QSO's). Radio sources. X-ray sources.
Jin, BoCheng
2011-12-01
Organic and inorganic fiber reinforced composites with innumerable fiber orientation distributions and fiber geometries are abundantly available in several natural and synthetic structures. Inorganic glass fiber composites have been introduced to numerous applications due to their economical fabrication and tailored structural properties. Numerical characterization of such composite material systems is necessitated due to their intrinsic statistical nature, which renders extensive experimentation prohibitively time consuming and costly. To predict various mechanical behavior and characterizations of Uni-Directional Fiber Composites (UDFC) and Random Fiber Composites (RaFC), we numerically developed Representative Volume Elements (RVE) with high accuracy and efficiency and with complex fiber geometric representations encountered in uni-directional and random fiber networks. In this thesis, the numerical simulations of unidirectional RaFC fiber strand RVE models (VF>70%) are first presented by programming in ABAQUS PYTHON. Secondly, when the cross sectional aspect ratios (AR) of the second phase fiber inclusions are not necessarily one, various types of RVE models with different cross sectional shape fibers are simulated and discussed. A modified random sequential absorption algorithm is applied to enhance the volume fraction number (VF) of the RVE, which the mechanical properties represents the composite material. Thirdly, based on a Spatial Segment Shortest Distance (SSSD) algorithm, a 3-Dimentional RaFC material RVE model is simulated in ABAQUS PYTHON with randomly oriented and distributed straight fibers of high fiber aspect ratio (AR=100:1) and volume fraction (VF=31.8%). Fourthly, the piecewise multi-segments fiber geometry is obtained in MATLAB environment by a modified SSSD algorithm. Finally, numerical methods including the polynomial curve fitting and piecewise quadratic and cubic B-spline interpolation are applied to optimize the RaFC fiber geometries
Johnson, Kenneth L.; White, K. Preston, Jr.
2012-01-01
The NASA Engineering and Safety Center was requested to improve on the Best Practices document produced for the NESC assessment, Verification of Probabilistic Requirements for the Constellation Program, by giving a recommended procedure for using acceptance sampling by variables techniques as an alternative to the potentially resource-intensive acceptance sampling by attributes method given in the document. In this paper, the results of empirical tests intended to assess the accuracy of acceptance sampling plan calculators implemented for six variable distributions are presented.
Energy Technology Data Exchange (ETDEWEB)
Liu, Yunde [State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074 (China); School of Environmental Studies, China University of Geosciences, Wuhan 430074 (China); Zhou, Aiguo, E-mail: aiguozhou@cug.edu.cn [State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074 (China); School of Environmental Studies, China University of Geosciences, Wuhan 430074 (China); Gan, Yiqun; Li, Xiaoqian [State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074 (China); School of Environmental Studies, China University of Geosciences, Wuhan 430074 (China)
2016-04-01
Stable carbon isotope analysis has the potential to be used for assessing the performance of in situ remediation of organic contaminants. Successful application of this isotope technique requires understanding the magnitude and variability in carbon isotope fractionation associated with the reactions under consideration. This study investigated the influence of inorganic anions (sulfate, bicarbonate, and chloride) on carbon isotope fractionation of trichloroethene (TCE) during its degradation by persulfate activated with zero-valent iron. The results demonstrated that the significant carbon isotope fractionation (enrichment factors ε ranging from − 3.4 ± 0.3 to − 4.3 ± 0.3 ‰) was independent on the zero-iron dosage, sulfate concentration, and bicarbonate concentration. However, the ε values (ranging from − 7.0 ± 0.4 to − 13.6 ± 1.2 ‰) were dependent on the chloride concentration, indicating that chloride could significantly affect carbon isotope fractionation during TCE degradation by persulfate activated with zero-valent iron. The dependence of ε values on chloride concentration, indicated that TCE degradation mechanisms may be different from the degradation mechanism caused by sulfate radical (SO{sub 4}·{sup −}). Ignoring the effect of chloride on ε value may cause numerous uncertainties in quantitative assessment of the performance of the in situ chemical oxidation (ISCO). - Highlights: • Significant C isotope fractionation for TCE degradation by Fe{sup 0} activated persulfate. • The enrichment factors was independent of Fe{sup 0}, SO{sub 4}{sup 2−}, or HCO{sub 3}{sup −} concentration. • Cl{sup −} significantly influenced the carbon isotope fractionation.
Rocha, Paulo; Boto, João P; Lind, Pedro G
2015-01-01
We present a framework for describing the evolution of stochastic observables having a non-stationary distribution of values. The framework is applied to empirical volume-prices from assets traded at the New York stock exchange. Using Kullback-Leibler divergence we evaluate the best model out from four biparametric models standardly used in the context of financial data analysis. In our present data sets we conclude that the inverse $\\Gamma$-distribution is a good model, particularly for the distribution tail of the largest volume-price fluctuations. Extracting the time-series of the corresponding parameter values we show that they evolve in time as stochastic variables themselves. For the particular case of the parameter controlling the volume-price distribution tail we are able to extract an Ornstein-Uhlenbeck equation which describes the fluctuations of the largest volume-prices observed in the data. Finally, we discuss how to bridge from the stochastic evolution of the distribution parameters to the stoch...
Saini, Komal; Singh, Parminder; Singh, Prabhjot; Bajwa, B S; Sahoo, B K
2017-02-01
A survey was conducted to estimate equilibrium factor and unattached fractions of radon and thoron in different regions of Punjab state, India. Pin hole based twin cup dosimeters and direct progeny sensor techniques have been utilized for estimation of concentration level of radon, thoron and their progenies. Equilibrium factor calculated from radon, thoron and their progenies concentration has been found to vary from 0.15 to 0.80 and 0.008 to 0.101 with an average value of 0.44 and 0.036 for radon and thoron respectively. Equilibrium factor for radon has found to be highest in winter season and lowest in summer season whereas for thoron highest value is observed in winter and rainy season and lowest in summer. Unattached fractions of radon and thoron have been found to vary from 0.022 to 0.205 and 0.013 to 0.212 with an average value of 0.099 and 0.071 respectively. Unattached fractions have found to be highest in winter season and lowest in rainy and summer season. Copyright © 2016 Elsevier Ltd. All rights reserved.
Green, Philip; Babu, Benson A; Teruya, Sergio; Helmke, Stephen; Prince, Martin; Maurer, Mathew S
2013-01-01
Anemia, a common comorbidity in older adults with heart failure and a preserved ejection fraction (HFPEF), is associated with worse outcomes. The authors quantified the effect of anemia treatment on left ventricular (LV) structure and function as measured by cardiac magnetic resonance (CMR) imaging. A prospective, randomized single-blind clinical trial (NCT NCT00286182) comparing the safety and efficacy of epoetin alfa vs placebo for 24 weeks in which a subgroup (n=22) had cardiac magnetic resonance imaging (MRI) at baseline and after 3 and 6 months to evaluate changes in cardiac structure and function. Pressure volume (PV) indices were derived from MRI measures of ventricular volume coupled with sphygmomanometer-measured pressure and Doppler estimates of filling pressure. The end-systolic and end-diastolic PV relations and the area between them as a function of end-diastolic pressure, the isovolumic PV area (PVAiso), were calculated. Patients (75±10 years, 64% women) with HFPEF (EF=63%±15%) with an average hemoglobin of 10.3±1.1 gm/dL were treated with epoetin alfa using a dose-adjusted algorithm that increased hemoglobin compared with placebo (PHFPEF resulted in a significant increase in hemoglobin, without evident change in LV structure, function, or pressure volume relationships as measured quantitatively using CMR imaging.
Taylor, Graham K; Holbrook, Robert Iain; de Perera, Theresa Burt
2010-09-06
Fish must orient in three dimensions as they navigate through space, but it is unknown whether they are assisted by a sense of depth. In principle, depth can be estimated directly from hydrostatic pressure, but although teleost fish are exquisitely sensitive to changes in pressure, they appear unable to measure absolute pressure. Teleosts sense changes in pressure via changes in the volume of their gas-filled swim-bladder, but because the amount of gas it contains is varied to regulate buoyancy, this cannot act as a long-term steady reference for inferring absolute pressure. In consequence, it is generally thought that teleosts are unable to sense depth using hydrostatic pressure. Here, we overturn this received wisdom by showing from a theoretical physical perspective that absolute depth could be estimated during fast, steady vertical displacements by combining a measurement of vertical speed with a measurement of the fractional rate of change of swim-bladder volume. This mechanism works even if the amount of gas in the swim-bladder varies, provided that this variation occurs over much longer time scales than changes in volume during displacements. There is therefore no a priori physical justification for assuming that teleost fish cannot sense absolute depth by using hydrostatic pressure cues.
Liu, Yunde; Zhou, Aiguo; Gan, Yiqun; Li, Xiaoqian
2016-04-01
Stable carbon isotope analysis has the potential to be used for assessing the performance of in situ remediation of organic contaminants. Successful application of this isotope technique requires understanding the magnitude and variability in carbon isotope fractionation associated with the reactions under consideration. This study investigated the influence of inorganic anions (sulfate, bicarbonate, and chloride) on carbon isotope fractionation of trichloroethene (TCE) during its degradation by persulfate activated with zero-valent iron. The results demonstrated that the significant carbon isotope fractionation (enrichment factors ε ranging from -3.4±0.3 to -4.3±0.3‰) was independent on the zero-iron dosage, sulfate concentration, and bicarbonate concentration. However, the ε values (ranging from -7.0±0.4 to -13.6±1.2‰) were dependent on the chloride concentration, indicating that chloride could significantly affect carbon isotope fractionation during TCE degradation by persulfate activated with zero-valent iron. The dependence of ε values on chloride concentration, indicated that TCE degradation mechanisms may be different from the degradation mechanism caused by sulfate radical (SO4(-)). Ignoring the effect of chloride on ε value may cause numerous uncertainties in quantitative assessment of the performance of the in situ chemical oxidation (ISCO).
Ochoa Gonzalez, R; Weiss, D
2015-10-20
The zinc (Zn) isotope compositions of feed materials and combustion byproducts were investigated in three different coal-fired power plants, and the results were used to develop a generalized model that can account for Zn isotopic fractionation during coal combustion. The isotope signatures in the coal (δ(66)ZnIRMM) ranged between +0.73 and +1.18‰, values that fall well within those previously determined for peat (+0.6 ±2.0‰). We therefore propose that the speciation of Zn in peat determines the isotope fingerprint in coal. All of the bottom ashes collected in these power plants were isotopically depleted in the heavy isotopes relative to the coals, with δ(66)ZnIRMM values ranging between +0.26‰ and +0.64‰. This suggests that the heavy isotopes, possibly associated with the organic matter of the coal, may be preferentially released into the vapor phase. The fly ash in all of these power plants was, in contrast, enriched in the heavy isotopes relative to coal. The signatures in the fly ash can be accounted for using a simple unidirectional fractionation model with isotope fractionation factors (αsolid-vapor) ranging between 1.0003 and 1.0007, and we suggest that condensation is the controlling process. The model proposed allows, once the isotope composition of the feed coal is known, the constraining of the Zn signatures in the byproducts. This will now enable the integration of Zn isotopes as a quantitative tool for the source apportionment of this metal from coal combustion in the atmosphere.
Roden, C. A.; Bond, T. C.; Conway, S.; Osorto Pinel, B.; Maccarty, N.
2006-12-01
In a three-year study of field and laboratory emissions of traditional and improved biofuel cookstoves, we found that field measured particulate emissions of actual cooking events average 2.5 times those of reproduced lab emissions. Emission factors are highly dependent on the care and skill of the operator, and the resulting combustion; these do not appear to be accurately reproduced in the lab. The single scatter albedo (SSA) of the emissions is very low in both lab and field measurements, averaging about 0.3 for lab tests and around 0.5 for field tests, indicating that the primary particles are climate warming. In Honduras, improved stoves generally had lower emission factors than traditional stoves. Over the course of 3 summers we have measured field emissions from traditional cookstoves, relatively-new improved cookstoves, and "broken-in" improved cookstoves. For improved stoves, the presence of a chimney generally resulted in lower emission factors but left the SSA unaffected. Traditional cookstoves had an average PM emission factor of 8.5 g/kg significantly larger than previous studies. Particulate emission factors for improved cookstoves without and with chimneys averaged about 5.7 g/kg and 3.5 g/kg respectively. The elemental carbon (EC) fraction of PM varied significantly between individual tests, but averaged about 25% for each of the categories. Wood type affects on the PM emission factor, the SSA of the emissions and EC fraction. During our 2006 field measurements, we performed multiple emission measurements on the same stove while varying the fuel. Pine wood generally produced more PM than oak per kilogram of fuel. Additionally, Ocote, a resinous pitch pine often used in Central America for lighting fires, produces emissions which have a very low SSA and high EC fraction. We present the elemental carbon fraction and mass emission factors for different type of stoves and testing conditions. We summarize the characteristics of the particles emitted
Institute of Scientific and Technical Information of China (English)
Jian Hu; Ximing Xu; Guangjin Yuan; Wei Ge; Liming Xu; Aihua Zhang; Junjian Deng
2015-01-01
Objective The aim of this study was to investigate tumor volume changes with kilovoltage cone-beam computed tomography (kV-CBCT) and their dosimetric consequences for non-operative lung cancer during intensity-modulated radiotherapy (IMRT) or fractionated stereotactic radiotherapy. Methods Eighteen patients with non-operative lung cancer who received IMRT consisting of 1.8-2.2 Gy/fraction and five fractions per week or stereotactic radiotherapy with 5-8 Gy/fraction and three fractions a week were studied. kV-CBCT was performed once per week during IMRT and at every fraction during stereotactic radiotherapy. The gross tumor volume (GTV) was contoured on the kV-CBCT images, and adaptive treatment plans were created using merged kV-CBCT and primary planning computed tomogra-phy image sets. Tumor volume changes and dosimetric parameters, including the minimum dose to 95%(D95) or 1% (D1) of the planning target volume (PTV), mean lung dose (MLD), and volume of lung tissue that received more than 5 (V5), 10 (V10), 20 (V20), and 30 (V30) Gy were retrospectively analyzed. Results The average maximum change in GTV observed during IMRT or fractionated stereotactic radio-therapy was -25.85% (range, -13.09% --56.76%). The D95 and D1 of PTV for the adaptive treatment plans in all patients were not significantly different from those for the initial or former adaptive treatment plans. In patients with tumor volume changes of >20% in the third or fourth week of treatment during IMRT, adap-tive treatment plans offered clinically meaningful decreases in MLD and V5, V10, V20, and V30; however, in patients with tumor volume changes of 20% in the third or fourth week of treatment.
T-S variability and volume transport in the central Bay of Bengal during southwest monsoon
Digital Repository Service at National Institute of Oceanography (India)
Gopalakrishna, V.V.; Pednekar, S.M.; Murty, V.S.N.
The variability of temperature and salinity along 11 degrees N and 12 degrees N sections in the Bay of Bengal during southwest monsoon months (July-September) was found to be large in the upper 200 m west of 83 degrees E and east of 90 degrees E...
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Backus, George A.; Lowry, Thomas Stephen; Jones, Shannon M; Walker, La Tonya Nicole; Roberts, Barry L; Malczynski, Leonard A.
2017-06-01
This report uses the CMIP5 series of climate model simulations to produce country- level uncertainty distributions for use in socioeconomic risk assessments of climate change impacts. It provides appropriate probability distributions, by month, for 169 countries and autonomous-areas on temperature, precipitation, maximum temperature, maximum wind speed, humidity, runoff, soil moisture and evaporation for the historical period (1976-2005), and for decadal time periods to 2100. It also provides historical and future distributions for the Arctic region on ice concentration, ice thickness, age of ice, and ice ridging in 15-degree longitude arc segments from the Arctic Circle to 80 degrees latitude, plus two polar semicircular regions from 80 to 90 degrees latitude. The uncertainty is meant to describe the lack of knowledge rather than imprecision in the physical simulation because the emphasis is on unfalsified risk and its use to determine potential socioeconomic impacts. The full report is contained in 27 volumes.
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Backus, George A.; Lowry, Thomas Stephen; Jones, Shannon M; Walker, La Tonya Nicole; Roberts, Barry L; Malczynski, Leonard A.
2017-06-01
This report uses the CMIP5 series of climate model simulations to produce country- level uncertainty distributions for use in socioeconomic risk assessments of climate change impacts. It provides appropriate probability distributions, by month, for 169 countries and autonomous-areas on temperature, precipitation, maximum temperature, maximum wind speed, humidity, runoff, soil moisture and evaporation for the historical period (1976-2005), and for decadal time periods to 2100. It also provides historical and future distributions for the Arctic region on ice concentration, ice thickness, age of ice, and ice ridging in 15-degree longitude arc segments from the Arctic Circle to 80 degrees latitude, plus two polar semicircular regions from 80 to 90 degrees latitude. The uncertainty is meant to describe the lack of knowledge rather than imprecision in the physical simulation because the emphasis is on unfalsified risk and its use to determine potential socioeconomic impacts. The full report is contained in 27 volumes.
den Dunnen, Steven; Dankelman, Jenny; Kerkhoffs, Gino M M J; Tuijthof, Gabrielle J M
2016-09-01
Using water jets for orthopedic procedures that require bone drilling can be beneficial due to the absence of thermal damage and the always sharp cut. Previously, the influence of the water jet diameter and bone architectural properties on the drilling depth have been determined. To develop water jet instruments that can safely drill in orthopedic surgery, the impact of the two remaining primary factors were determined: the jet time (tjet [s]) and pressure (P [MPa]). To this end, 84 holes were drilled in porcine tali and femora with water jets using Ø 0.4mm nozzle. tjet was varied between 1, 3 and 5s and P between 50 and 70MPa. Drilling depths Lhole (mm), diameters Dhole (mm) and the volume of mineralized bone per unit volume (BV/TV) were determined with microCT scans. A non-linear regression analysis resulted in the predictive equation: Lhole= 0.22 * tjet(0.18) * (1.2-BV/TV) * (P-29) (R(2)=0.904). The established relation between the machine settings and drilling depth allows surgeons to adjust jet time and pressure for the patient׳s BV/TV to drill holes at a predetermined depth. For developers, the relation allows design decisions to be made that influence the dimensions, flexibility and accuracy of water jet instruments. For a pressure of 50MPa, the potential hole depth spread indicated by the 95% confidence interval is drilling can be applied in orthopedic surgery to drill holes in bone with controlled depth.
Directory of Open Access Journals (Sweden)
Wust Peter
2010-05-01
Full Text Available Abstract Background To assess radiobiological restrictions and tolerance doses as well as other toxic effects derived from repeated applications of single-fraction high dose rate irradiation of small liver volumes in clinical practice. Methods Twenty patients with liver metastases were treated repeatedly (2 - 4 times at identical or intersecting locations by CT-guided interstitial brachytherapy with varying time intervals. Magnetic resonance imaging using the hepatocyte selective contrast media Gd-BOPTA was performed before and after treatment to determine the volume of hepatocyte function loss (called pseudolesion, and the last acquired MRI data set was merged with the dose distributions of all administered brachytherapies. We calculated the BED (biologically equivalent dose for a single dose d = 2 Gy for different α/β values (2, 3, 10, 20, 100 based on the linear-quadratic model and estimated the tolerance dose for liver parenchyma D90 as the BED exposing 90% of the pseudolesion in MRI. Results The tolerance doses D90 after repeated brachytherapy sessions were found between 22 - 24 Gy and proved only slightly dependent on α/β in the clinically relevant range of α/β = 2 - 10 Gy. Variance analysis showed a significant dependency of D90 with respect to the intervals between the first irradiation and the MRI control (p 90 and the pseudolesion's volume. No symptoms of liver dysfunction or other toxic effects such as abscess formation occurred during the follow-up time, neither acute nor on the long-term. Conclusions Inactivation of liver parenchyma occurs at a BED of approx. 22 - 24 Gy corresponding to a single dose of ~10 Gy (α/β ~ 5 Gy. This tolerance dose is consistent with the large potential to treat oligotopic and/or recurrent liver metastases by CT-guided HDR brachytherapy without radiation-induced liver disease (RILD. Repeated small volume irradiation may be applied safely within the limits of this study.
Thavendiranathan, Paaladinesh; Popović, Zoran B; Flamm, Scott D; Dahiya, Arun; Grimm, Richard A; Marwick, Thomas H
2013-11-01
Although not recommended in isolation, visual estimation of echocardiographic ejection fraction (EF) is widely applied to confirm quantitative EF. However, interobserver variability for EF estimation has been reported to be as high as 14%. The aim of this study was to determine whether self-directed education could improve the accuracy and interobserver variability of visual estimation of EF and whether a multireader estimate improves measurement precision. Thirty-one participants provided single-point EF estimates for 30 echocardiograms with a spectrum of EFs, image quality, and clinical contexts in patients undergoing cardiac magnetic resonance (CMR) within 48 hours. Participants received their own case-by-case variance from CMR EF, and the 10 cases with the largest reader variability were discussed along with corresponding CMR images. Self-directed learning was undertaken by side-by-side review of echocardiographic and CMR images. Two months later, 20 new cases were shown to the same 31 participants, using the same methodology. The baseline interobserver variability of ±0.120 improved to ±0.097 after the intervention. EF misclassification (defined as ±0.05 of CMR EF) was reduced from 56% to 47% (P self-directed intervention modestly decreased interobserver variability and improved the accuracy of EF measurements. Combined physician-sonographer EF reporting improved the precision of EF estimates. Copyright © 2013 American Society of Echocardiography. Published by Mosby, Inc. All rights reserved.
Mean Platelet Volume and Arterial Stiffness – Clinical Relationship and Common Genetic Variability
Panova-Noeva, Marina; Arnold, Natalie; Hermanns, M. Iris; Prochaska, Jürgen H.; Schulz, Andreas; Spronk, Henri M.; Binder, Harald; Pfeiffer, Norbert; Beutel, Manfred; Blankenberg, Stefan; Zeller, Tanja; Lotz, Johannes; Münzel, Thomas; Lackner, Karl J.; ten Cate, Hugo; Wild, Philipp S.
2017-01-01
Vessel wall stiffening is an important clinical parameter, but it is unknown whether platelets, key elements in the pathogenesis of arterial thrombosis, are associated with arterial stiffness. The present studies sought to determine whether mean platelet volume (MPV), a potential marker of platelet activation, is linked to vascular elasticity as assessed by the augmentation index (AIx), in 15,010 individuals from the population-based Gutenberg Health Study. Multivariable analysis showed that MPV in both males (β 0.776; 95thCI [0.250;1.16]; p = 0.0024) and females (β 0.881[0.328;1.43]; p = 0.0018) is strongly associated with AIx. Individuals with MPV and AIx above the sex-specific medians had worse survival. Association analysis between MPV-related genetic variants and arterial stiffness identified four genetic variants in males and one in females related with AIx. Cox regression analysis for mortality identified one of these joint genetic variants close to ring finger protein 145 gene (RNF145, rs10076782) linked with increased mortality (hazard ratio 2.02; 95thCI [1.35;3.02]; p = 0.00061). Thus, these population-based data demonstrate a close relation between platelet volume as a potential marker of platelet activation and arterial stiffness in both sexes. Further research is warranted to further elucidate the mechanisms underlying larger platelets‘ role in arterial stiffening including the role of shared common genetics. PMID:28059166
Leite, Argentina; Paula Rocha, Ana; Eduarda Silva, Maria
2013-06-01
Heart Rate Variability (HRV) series exhibit long memory and time-varying conditional variance. This work considers the Fractionally Integrated AutoRegressive Moving Average (ARFIMA) models with Generalized AutoRegressive Conditional Heteroscedastic (GARCH) errors. ARFIMA-GARCH models may be used to capture and remove long memory and estimate the conditional volatility in 24 h HRV recordings. The ARFIMA-GARCH approach is applied to fifteen long term HRV series available at Physionet, leading to the discrimination among normal individuals, heart failure patients, and patients with atrial fibrillation.
Agnan, Y.; Obrist, D.; Edwards, G. C.; Moore, C.; Hedge, C.; Helmig, D.; Paxton, D.; Jacques, H.
2015-12-01
An important global source of atmospheric methane (CH4) is production in tundra soils (an important global source). To place constraints on the potential role that tundra soils play in global CH4 cycling, we have been continuously measuring mole the air space in soils, snow, and the atmosphere as gradient-based surface-atmosphere fluxes for arctic tundra at Toolik Field Station (68° 38' N) starting in October 2014. We have found that atmospheric CH4 mole fractions were, on average, relatively constant during the first 9 months of sampling (averaging 1.93 µmol mol-1), with pronounced diel patterns starting in May and nighttime exceeding daytime mole fractions. However, gradients measured within the soil profile showed high variability in air withdrawn from different locations of these tundra soils (Typic Aquiturbels), with one soil profile indicating a CH4 sink during fall until January; mole fractions were similar to the atmospheric measurements during winter indicating no source or sink (average 1.89 µmol mol-1). A second soil profile 5 m away showed production of CH4 (average 2.48 µmol mol-1, two-times higher than atmospheric levels), even during mid-winter when soil temperatures were below -10 °C. Measurements of CH4 in interstitial snowpack air also exhibited a similar combination of sources and sinks. We used micrometeorological gradient surface flux measurements to confirm that the area was a net source of CH4 in fall, winter, and spring, with emissions averaging 26.6, 25.2, and 16.8 mg m-2 d-1, respectively. In the summer months, we saw strong diel flux patterns with deposition during day and emission at night, corresponding with observed diel variability in CH4 snowpack mole fractions. Our results indicated a high variability of tundra landscape CH4 fluxes, which locally shift from sources to sinks with high temporal variability. CH4 oxidation by methanotrophic bacteria probably occurs in tundra soils, confirming observations in one soil, snowpack, and
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Prabhu, B. [Department of Mechanical, Materials, and Aerospace Engineering, University of Central Florida, Orlando, FL 32816-2450 (United States); Suryanarayana, C. [Department of Mechanical, Materials, and Aerospace Engineering, University of Central Florida, Orlando, FL 32816-2450 (United States)]. E-mail: csuryana@mail.ucf.edu; An, L. [Department of Mechanical, Materials, and Aerospace Engineering, University of Central Florida, Orlando, FL 32816-2450 (United States); Advanced Materials Processing and Analysis Center, University of Central Florida, Orlando, FL 32816-2455 (United States); Vaidyanathan, R. [Department of Mechanical, Materials, and Aerospace Engineering, University of Central Florida, Orlando, FL 32816-2450 (United States); Advanced Materials Processing and Analysis Center, University of Central Florida, Orlando, FL 32816-2455 (United States)
2006-06-15
Al-Al{sub 2}O{sub 3} metal matrix composite (MMC) powders with volume fractions of 20, 30, and 50% Al{sub 2}O{sub 3} were synthesized by high-energy milling of the blended component powders. The particle sizes of Al{sub 2}O{sub 3} studied were 50 nm, 150 nm, and 5 {mu}m. A uniform distribution of the Al{sub 2}O{sub 3} reinforcement in the Al matrix was successfully obtained after milling the powders for a period of 20 h at a ball-to-powder ratio of 10:1 in a SPEX mill. The uniform distribution of Al{sub 2}O{sub 3} in the Al matrix was confirmed by characterizing these nanocomposite powders by scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), X-ray mapping, and X-ray diffraction (XRD) techniques.
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Hamadeh, H. [AECS, Physics Department, P.O. Box 6091, Damascus (Syria)
2010-07-15
A comparison of the temperature dependence of the IV characteristics parameters of hydrogenated silicon pin solar cells with intrinsic layers made of polymorphous silicon (pm-Si:H) and of {mu}c-Si:H with low crystalline volume fraction has been performed. When using pm-Si:H, higher efficiency and higher filling factors are achieved over a wide temperature range. Diode quality factors of both types of cells show similar temperature dependence. Recombination processes over the whole intrinsic layer dominates the forward current. A change of the cell parameters under illumination is also observed. The transport mechanism of both cells is similar in the temperature range that is important for most applications. Due to its optical and transport properties, pm-Si:H poses a very interesting alternative to {mu}c-Si:H and a-Si:H in the temperature range of normal terrestrial applications. (author)
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Kearney, Sean P. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Guildenbecher, Daniel Robert [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Winters, Caroline [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Farias, Paul Abraham [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Grasser, Thomas W. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hewson, John C. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
2015-09-01
We present a detailed set of measurements from a piloted, sooting, turbulent C _{2} H _{4 }- fueled diffusion flame. Hybrid femtosecond/picosecond coherent anti-Stokes Raman scattering (CARS) is used to monitor temperature and oxygen, while laser-induced incandescence (LII) is applied for imaging of the soot volume fraction in the challenging jet-flame environment at Reynolds number, Re = 20,000. Single-laser shot results are used to map the mean and rms statistics, as well as probability densities. LII data from the soot-growth region of the flame are used to benchmark the soot source term for one-dimensional turbulence (ODT) modeling of this turbulent flame. The ODT code is then used to predict temperature and oxygen fluctuations higher in the soot oxidation region higher in the flame.
Shivvers, Isaac; Zheng, Weikang; Filippenko, Alexei V; Silverman, Jeffrey M; Liu, Yuqian; Matheson, Thomas; Pastorello, Andrea; Graur, Or; Foley, Ryan J; Chornock, Ryan; Smith, Nathan; Leaman, Jesse; Benetti, Stefano
2016-01-01
We re-examine the classifications of supernovae (SNe) presented in the Lick Observatory Supernova Search (LOSS) volume-limited sample with a focus on the stripped-envelope SNe. The LOSS volumetric sample, presented by Leaman et al. (2011) and Li et al. (2011b), was calibrated to provide meaningful measurements of SN rates in the local universe; the results presented therein continue to be used for comparisons to theoretical and modeling efforts. Many of the objects from the LOSS sample were originally classified based upon only a small subset of the data now available, and recent studies have both updated some subtype distinctions and improved our ability to perform robust classifications, especially for stripped-envelope SNe. We re-examine the spectroscopic classifications of all events in the LOSS volumetric sample (180 SNe and SN impostors) and update them if necessary. We discuss the populations of rare objects in our sample including broad-lined Type Ic SNe, Ca-rich SNe, SN 1987A-like events (we identify...
Directory of Open Access Journals (Sweden)
M.R. VADRUCCI
2005-06-01
Full Text Available Spatial and seasonal patterns of variation of fractionated phytoplankton biomass and primary production and their relationships with nutrient concentrations were analyzed along an inshore - offshore gradient and in relation to the presence of a frontal system in the Northern Adriatic Sea. Sampling was carried out in winter and summer during four oceanographic cruises (June 1996 and 1997, February 1997 and 1998 as part of the PRISMA II project. Water samples for determining nutrient concentrations, phytoplankton biomass (as Chla and primary production (as 14 C assimilation were collected at five optical depths. Sampling stations were located along 2 or 4 parallel transects arranged perpendicularly to the shoreline and the frontal system. The transects were located at such a distance from the coast that the frontal system crossed them at their halfway point. Total dissolved nitrogen (TDN and total dissolved phosphorus concentrations (TDP were 12.41 ± 3 .95 mM and 0.146 ± 0 .070 mM, respectively. The values in the two seasonal periods were similar, decreasing along the inshore-offshore gradient. Values for phytoplankton biomass and primary productionwere higher in the winter than the summer cruises, and decreased, in both seasonal periods, along the inshore / offshore gradient. Moreover, in both seasonal periods, picophytoplankton dominated both biomass and productivity, (56% and 44%, respectively at stations beyond the frontal system, while microphytoplankton was more important at stations inside it (44% and 44%, respectively. Total phytoplankton biomass and primary production were directly related to nutrient concentrations. Regarding size classes, significant patterns of variation with nutrients were observed particularly for biomass. The results indicate that the size structure and function of phytoplankton guilds seem to be mediated by nutrient inflow, as well as by competitive interaction among size fractions.
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Kim, Young Suk [Jeju National University School of Medicine, Department of Radiation Oncology, Jeju National University Hospital, Jeju (Korea, Republic of); Kim, Jun Won; Lee, Ik Jae [Yonsei University College of Medicine, Department of Radiation Oncology, Gangnam Severance Hospital, Seoul (Korea, Republic of); Yoon, Won Sup [Korea University Medical Center, Department of Radiation Oncology, Ansan Hospital, Ansan (Korea, Republic of); Kang, Min Kyu [Kyungpook National University School of Medicine, Department of Radiation Oncology, Daegu (Korea, Republic of); Kim, Tae Hyun [National Cancer Center, Center for Liver Cancer, Goyang (Korea, Republic of); Kim, Jin Hee [Keimyung University School of Medicine, Department of Radiation Oncology, Dongsan Medical Center, Daegu (Korea, Republic of); Lee, Hyung-Sik [Dong-A University College of Medicine, Department of Radiation Oncology, Busan (Korea, Republic of); Park, Hee Chul [Sungkyunkwan University School of Medicine, Department of Radiation Oncology, Samsung Medical Center, Seoul (Korea, Republic of); Jang, Hong Seok; Kay, Chul Seung [The Catholic University of Korea College of Medicine, Department of Radiation Oncology, Seoul (Korea, Republic of); Yoon, Sang Min [University of Ulsan College of Medicine, Department of Radiation Oncology, Asan Medical Center, Seoul (Korea, Republic of); Kim, Mi-Sook [Korea Institute of Radiological and Medical Sciences, Department of Radiation Oncology, Seoul (Korea, Republic of); Seong, Jinsil [Yonsei University College of Medicine, Department of Radiation Oncology, Severance Hospital, Seodaemun-gu, Seoul (Korea, Republic of)
2016-10-15
There has been increasing use of external beam radiotherapy for localized treatment of hepatocellular carcinoma (HCC) with both palliative and curative intent. Quality control of target delineation in primary HCC is essential to deliver adequate doses of radiation to the primary tumor while preserving adjacent healthy organs. We analyzed interobserver variability in gross tumor volume (GTV) delineation for HCC. Twelve radiation oncologists specializing in liver malignancy participated in a multi-institutional contouring dummy-run study of nine HCC cases and independently delineated GTV on the same set of provided computed tomography images. Quantitative analysis was performed using an expectation maximization algorithm for simultaneous truth and performance level estimation (STAPLE) with kappa statistics calculating agreement between physicians. To quantify the interobserver variability of GTV delineations, the ratio of the actual delineated volume to the estimated consensus volume (STAPLE), the ratio of the common and encompassing volumes, and the coefficient of variation were calculated. The median kappa agreement level was 0.71 (range 0.28-0.86). The ratio of the actual delineated volume to the estimated consensus volume ranged from 0.19 to 1.93 (median 0.94) for all cases. The ratio of the common and encompassing volumes ranged from 0.001 to 0.56 (median 0.25). The coefficient of variation for GTV delineation ranged from 8 to 57 % (median 26 %). The interobserver variability in target delineation of HCC GTV in this study is noteworthy. Multi-institution studies involving radiotherapy for HCC require appropriate quality assurance programs for target delineation. (orig.) [German] Die externe kurative Strahlentherapie ist zunehmend bei der lokalisierten Behandlung hepatozellulaerer Karzinome (HCC) in palliativer und kurativer Absicht in Gebrauch. Eine Qualitaetskontrolle der Zielabgrenzung beim primaeren HCC ist entscheidend, um die passende Dosis fuer die
Agustini, S.; Wahyuono, R. A.; Sawitri, D.; Risanti, D. D.
2013-09-01
Since its first development, efforts to improve efficiency of Dye Sensitized Solar Cell (DSSC) are continuously carried out, either through selection of dye materials, the type of semiconductor, counter electrode design or the sandwiched structure. It is widely known that anatase and rutile are phases of TiO2 that often being used for fabrication of DSSC. Rutile is thermodynamically more stable phase having band-gap suitable for absorption of sunlight spectrum. On the other hand, anatase has higher electrical conductivity, capability to adsorp dye as well as higher electron diffusion coefficient than those of rutile. Present research uses mangosteen pericarp and Rhoeo spathacea extracted in ethanol as natural dye containing anthocyanin. These dyes were characterized by using UV-Vis and FTIR, showing that the absorption maxima peaks obtained at 389 nm and 413 nm, for mangosteen and Rhoeo spathacea, respectively. The nano TiO2 was prepared by means of co-precipitation method. The particle size were 9-11 nm and 54.5 nm for anatase and rutile, respectively, according to Scherrer's equation. DSSCs were fabricated in various volume fractions of anatase and rutile TiO2. The fabricated DSSCs were tested under 17 mW/cm2 of solar irradiation. The current-voltage (I-V) characteristic of DSSCs employing 75%: 25% volume fraction of anatase and rutile TiO2 have outstanding result than others. The highest conversion efficiencies of 0.037% and 0.013% are obtained for DSSC employing natural dye extract from mangosteen pericarp and Rhoeo spathacea, respectively.
Schneider, T.; Botta, N.; Geratz, K. J.; Klein, R.
1999-11-01
When attempting to compute unsteady, variable density flows at very small or zero Mach number using a standard finite volume compressible flow solver one faces at least the following difficulties: (i) Spatial pressure variations vanish as the Mach number M→0, but they do affect the velocity field at leading order; (ii) the resulting spatial homogeneity of the leading order pressure implies an elliptic divergence constraint for the energy flux; (iii) violations of this constraint crucially affect the transport of mass, preventing a code to properly advect even a constant density distribution. We overcome these difficulties through a new algorithm for constructing numerical fluxes in the context of multi-dimensional finite volume methods in conservation form. The construction of numerical fluxes involves: (1) An explicit upwind step yielding predictions for the nonlinear convective flux components. (2) A first correction step that introduces pressure gradients which guarantee compliance of the convective fluxes with a divergence constraint. This step requires the solution of a first Poisson-type equation. (3) A second projection step which provides the yet unknown (non-convective) pressure contribution to the total flux of momentum. This second projection requires the solution of another Poisson-type equation and yields the cell centered velocity field at the new time. This velocity field exactly satisfies a divergence constraint consistent with the asymptotic limit. Step (1) can be done by any standard finite volume compressible flow solver. The input to steps (2) and (3) involves solely the fluxes from step (1) and is independent of how these were obtained. Thus, our approach allows any such solver to be extended to compute variable density incompressible flows.
Gallego, J.; Niñerola-Baizán, A.; Cot, A.; Aguiar, P.; Crespo, C.; Falcón, C.; Lomeña, F.; Sempau, J.; Pavía, J.; Ros, D.
2015-08-01
The aim of this work was to evaluate the influence of anatomical variability between subjects and of the partial volume effect (PVE) on the standardized Specific Uptake Ratio (SUR) in [123I]FP-bib SPECT studies. To this end, magnetic resonance (MR) images of 23 subjects with differences in the striatal volume of up to 44% were segmented and used to generate a database of 138 Monte Carlo simulated SPECT studies. Data included normal uptakes and pathological cases. Studies were reconstructed by filtered back projection (FBP) and the ordered-subset expectation-maximization algorithm. Quantification was carried out by applying a reference method based on regions of interest (ROIs) derived from the MR images and ROIs derived from the Automated Anatomical Labelling map. Our results showed that, regardless of anatomical variability, the relationship between calculated and true SUR values for caudate and putamen could be described by a multiple linear model which took into account the spill-over phenomenon caused by PVE ({{R}2}≥slant 0.963 for caudate and ≥0.980 for putamen) and also by a simple linear model (R2 ≥ 0.952 for caudate and ≥0.973 for putamen). Calculated values were standardized by inverting both linear systems. Differences between standardized and true values showed that, although the multiple linear model was the best approach in terms of variability ({χ2} ≥ 11.79 for caudate and ≤7.36 for putamen), standardization based on a simple linear model was also suitable ({χ2} ≥ 12.44 for caudate and ≤12.57 for putamen).
Basso, Luana S.; Gatti, Luciana V.; Gloor, Manuel; Miller, John B.; Domingues, Lucas G.; Correia, Caio S. C.; Borges, Viviane F.
2016-01-01
The Amazon Basin is an important region for global CH4 emissions. It hosts the largest area of humid tropical forests, and around 20% of this area is seasonally flooded. In a warming climate it is possible that CH4 emissions from the Amazon will increase both as a result of increased temperatures and precipitation. To examine if there are indications of first signs of such changes we present here a 13 year (2000-2013) record of regularly measured vertical CH4 mole fraction profiles above the eastern Brazilian Amazon, sensitive to fluxes from the region upwind of Santarém (SAN), between SAN and the Atlantic coast. Using a simple mass balance approach, we find substantial CH4 emissions with an annual average flux of 52.8 ± 6.8 mg CH4 m-2 d-1 over an area of approximately 1 × 106 km2. Fluxes are highest in two periods of the year: in the beginning of the wet season and during the dry season. Using a CO:CH4 emission factor estimated from the profile data, we estimated a contribution of biomass burning of around 15% to the total flux in the dry season, indicating that biogenic emissions dominate the CH4 flux. This 13 year record shows that CH4 emissions upwind of SAN varied over the years, with highest emissions in 2008 (around 25% higher than in 2007), mainly during the wet season, representing 19% of the observed global increase in this year.
Rueckriegel, Stefan M; Bruhn, Harald; Thomale, Ulrich W; Hernáiz Driever, Pablo
2015-07-01
Disease and therapy cause brain damage and subsequent functional loss in pediatric patients with posterior fossa tumors. Treatment-related toxicity factors are resection in patients with pilocytic astrocytoma (PA) and, additionally, cranio-spinal irradiation together with chemotherapy in patients with medulloblastoma (MB). We tested whether damage to white matter (WM) as revealed by diffusion tensor MR imaging (DTI) correlated with specific cognitive and motor impairments in survivors of pediatric posterior fossa tumors. Eighteen MB (mean age ± SD, 15.2 ± 4.9 y) and 14 PA (12.6 ± 5.0 y) survivors were investigated with DTI on a 3-Tesla-MR system. We identified fractional anisotropy (FA) of WM, the volume ratio of WM to gray matter and cerebrospinal fluid (WM/GM + CSF), and volume of specific frontocerebellar tracts. Ataxia was assessed using the International Cooperative Ataxia Rating Scale (ICARS), while the Wechsler Intelligence Scale for Children determined full-scale intelligence quotients (FSIQ). Amsterdam Neuropsychological Tasks (ANT) was used to assess processing speed. Handwriting automation was analyzed using a digitizing graphic tablet. The WM/GM + CSF ratio correlated significantly with cognitive measures (IQ, P = 0.002; ANT baseline speed, P = 0.04; ANT shifting attention, P = 0.004). FA of skeletonized tracts correlated significantly with FSIQ (P = 0.008), ANT baseline speed (P = 0.028) and ANT shifting attention (P = 0.045). Moreover, frontocerebellar tract volumes correlated with both the FSIQ (P = 0.011) and ICARS (P = 0.007). DTI provides a method for quantification of WM damage by tumor and by therapy-associated effects in survivors of pediatric posterior fossa tumors. DTI-derived WM integrity may be a representative marker for cognitive and motor deterioration. © 2015 Wiley Periodicals, Inc.
Yagci, Ali Levent; Santanello, Joseph A.; Jones, John; Barr, Jordan
2017-01-01
A remote-sensing-based model to estimate evaporative fraction (EF) the ratio of latent heat (LE; energy equivalent of evapotranspiration -ET-) to total available energy from easily obtainable remotely-sensed and meteorological parameters is presented. This research specifically addresses the shortcomings of existing ET retrieval methods such as calibration requirements of extensive accurate in situ micro-meteorological and flux tower observations, or of a large set of coarse-resolution or model-derived input datasets. The trapezoid model is capable of generating spatially varying EF maps from standard products such as land surface temperature [T(sub s)] normalized difference vegetation index (NDVI)and daily maximum air temperature [T(sub a)]. The 2009 model results were validated at an eddy-covariance tower (Fluxnet ID: US-Skr) in the Everglades using T(sub s) and NDVI products from Landsat as well as the Moderate Resolution Imaging Spectroradiometer (MODIS) sensors. Results indicate that the model accuracy is within the range of instrument uncertainty, and is dependent on the spatial resolution and selection of end-members (i.e. wet/dry edge). The most accurate results were achieved with the T(sub s) from Landsat relative to the T(sub s) from the MODIS flown on the Terra and Aqua platforms due to the fine spatial resolution of Landsat (30 m). The bias, mean absolute percentage error and root mean square percentage error were as low as 2.9% (3.0%), 9.8% (13.3%), and 12.1% (16.1%) for Landsat-based (MODIS-based) EF estimates, respectively. Overall, this methodology shows promise for bridging the gap between temporally limited ET estimates at Landsat scales and more complex and difficult to constrain global ET remote-sensing models.
Evans, David C; Forbes, Rachel; Jones, Christian; Cotterman, Robert; Njoku, Chinedu; Thongrong, Cattleya; Tulman, David; Bergese, Sergio D; Thomas, Sheela; Papadimos, Thomas J; Stawicki, Stanislaw P
2016-01-01
Introduction: Enteral nutrition (EN) is very important to optimizing outcomes in critical illness. Debate exists regarding the best strategy for enteral tube feeding (TF), with concerns that bolus TF (BTF) may increase glycemic variability (GV) but result in fewer nutritional interruptions than continuous TF (CTF). This study examines if there is a difference in GV, insulin usage, TF volume, and caloric delivery among intensive care patients receiving BTF versus CTF. We hypothesize that there are no significant differences between CTF and BTF when comparing the above parameters. Materials and Methods: Prospective, randomized pilot study of critically ill adult patients undergoing percutaneous endoscopic gastrostomy (PEG) placement for EN was performed between March 1, 2012 and May 15, 2014. Patients were randomized to BTF or CTF. Glucose values, insulin use, TF volume, and calories administered were recorded. Data were organized into 12-h epochs for statistical analyses and GV determination. In addition, time to ≥80% nutritional delivery goal, demographics, Acute Physiology and Chronic Health Evaluation II scores, and TF interruptions were examined. When performing BTF versus CTF assessments, continuous parameters were compared using Mann–Whitney U-test or repeated measures t-test, as appropriate. Categorical data were analyzed using Fisher's exact test. Results: No significant demographic or physiologic differences between the CTF (n = 24) and BTF (n = 26) groups were seen. The immediate post-PEG 12-h epoch showed significantly lower GV and median TF volume for patients in the CTF group. All subsequent epochs (up to 18 days post-PEG) showed no differences in GV, insulin use, TF volume, or caloric intake. Insulin use for both groups increased when comparing the first 24 h post-PEG values to measurements from day 8. There were no differences in TF interruptions, time to ≥80% nutritional delivery goal, or hypoglycemic episodes. Conclusions: This study
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Onder, M.; Sarac, S.; Cevik, E. [Osmangazi University, Eskisehir (Turkey). Dept. of Mining Engineering
2006-09-15
Auxiliary ventilation is performed by carrying intake or return air in ducts. The complete elimination of air leakage from or into the ducting system is impossible due to duct quality and numerous joints in ducting system. The auxiliary ventilation systems for long drivages often require the use of multiple fans. There are many methods proposed for the analysis air flow problems in leaky ducts. In this study, a method known as 'series-parallel combination of the duct and leakage path' has been introduced and a computer program has been developed based on this method. In order to design the conditions of an auxiliary ventilated drivage, in situ measurement have been made in the Omerler underground coal mine (Turkey) and the related data necessary for this study was collected. The presently developed program was tested using these data, and it was found that the measured and calculated values are quite close. The effective operational parameters governing auxiliary ventilation have been investigated and the effects of these variables on the volume rate of air flow reaching long drivage face have been examined by using linear regression analysis. Finally, it was concluded that the increase of duct diameter has prime importance in achieving the adequate air flow to the face and that for the auxiliary fans considered in this study the selection of fan does not greatly affect the volume rate reaching the face in a long duct line.
D'Errico, Luigia; Lamacie, Mariana M; Jimenez Juan, Laura; Deva, Djeven; Wald, Rachel M; Ley, Sebastian; Hanneman, Kate; Thavendiranathan, Paaladinesh; Wintersperger, Bernd J
2016-09-22
Test-retest reproducibility is of utmost importance in follow-up of right ventricular (RV) volumes and function; optimal slice orientation though is not yet known. We compared test-retest reproducibility and intra-/inter-observer variability of right ventricular (RV) volumes and function assessed with short-axis and transverse cardiovascular magnetic resonance (CMR). Eighteen volunteers underwent cine CMR for RV assessment obtaining ventricular coverage in short-axis and transverse slice orientation. Additional 2D phase contrast flow imaging of the main pulmonary artery (MPA) was performed. After complete repositioning repeat acquisitions were performed. Data sets were contoured by two blinded observers. Statistical analysis included Student's t-test, Bland-Altman plots, intra-class correlation coefficient (ICC) and 2-way ANOVA, SEM and minimal detectable difference calculations. Heart rates (65.0 ± 7.4 vs. 67.6 ± 9.9 bpm; P = 0.1) and MPA flow (89.8 ± 16.6 vs. 87.2 ± 14.9 mL; P = 0.1) did not differ between imaging sessions. EDV and ESV demonstrated an inter-study bias of 0.4 %[-9.5 %,10.3 %] and 2.1 %[-12.3 %,16.4 %] for short-axis and 1.1 %[-7.3 %,9.4 %] and 0.8 %[-16.0 %,17.6 %] for transverse orientation, respectively. There was no significant interaction between imaging orientation and interstudy reproducibility (p = 0.395-0.824), intra-observer variability (p = 0.726-0.862) or inter-observer variability (p = 0.447-0.706) by 2-way ANOVA. Inter-observer agreement by ICC was greater for short axis versus transverse orientation for all parameters (0.769-0.986 vs. 0.625-0.983, respectively). Minimal detectable differences for short axis and transverse orientations were 10.1 mL/11.5 mL for EDV, 8.3 mL/8.4 mL for ESV and 4.1 % vs. 4.7 % for EF, respectively. Short-axis and transverse orientation both provide reliable and reproducible measures for follow-up of RV volumes and global function. Therefore
Deichmann, Ralf; Pfeilschifter, Waltraud; Hattingen, Elke; Singer, Oliver C.; Wagner, Marlies
2016-01-01
Purpose Quantitative T2'-mapping detects regional changes of the relation of oxygenated and deoxygenated hemoglobin (Hb) by using their different magnetic properties in gradient echo imaging and might therefore be a surrogate marker of increased oxygen extraction fraction (OEF) in cerebral hypoperfusion. Since elevations of cerebral blood volume (CBV) with consecutive accumulation of Hb might also increase the fraction of deoxygenated Hb and, through this, decrease the T2’-values in these patients we evaluated the relationship between T2’-values and CBV in patients with unilateral high-grade large-artery stenosis. Materials and Methods Data from 16 patients (13 male, 3 female; mean age 53 years) with unilateral symptomatic or asymptomatic high-grade internal carotid artery (ICA) or middle cerebral artery (MCA) stenosis/occlusion were analyzed. MRI included perfusion-weighted imaging and high-resolution T2’-mapping. Representative relative (r)CBV-values were analyzed in areas of decreased T2’ with different degrees of perfusion delay and compared to corresponding contralateral areas. Results No significant elevations in cerebral rCBV were detected within areas with significantly decreased T2’-values. In contrast, rCBV was significantly decreased (pperfusion delay and decreased T2’. Furthermore, no significant correlation between T2’- and rCBV-values was found. Conclusions rCBV is not significantly increased in areas of decreased T2’ and in areas of restricted perfusion in patients with unilateral high-grade stenosis. Therefore, T2’ should only be influenced by changes of oxygen metabolism, regarding our patient collective especially by an increase of the OEF. T2’-mapping is suitable to detect altered oxygen consumption in chronic cerebrovascular disease. PMID:27560515
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Thomas eStöggl
2014-02-01
Full Text Available Endurance athletes integrate four conditioning concepts in their training programs: high-volume training (HVT, ‘threshold-training’ (THR, high-intensity interval training (HIIT and a combination of these aforementioned concepts known as polarized training (POL. The purpose of this study was to explore which of these four training concepts provides the greatest response on key components of endurance performance in well-trained endurance athletes. Methods: Forty eight runners, cyclists, triathletes and cross-country skiers (peak oxygen uptake: (VO2peak: 62.6±7.1 mL∙min-1∙kg-1 were randomly assigned to one of four groups performing over nine weeks. An incremental test, work economy and a VO2peak tests were performed. Training intensity was heart rate controlled. Results: POL demonstrated the greatest increase in VO2peak (+6.8 ml∙min∙kg-1 or 11.7%, P0.05. Conclusion: POL resulted in the greatest improvements in most key variables of endurance performance in well-trained endurance athletes. THR or HVT did not lead to further improvements in performance related variables.
Concepción Ramos, Maria
2015-04-01
This work investigated the variability in soil water recorded within the vineyard plots related to soil properties and management practices and its influence on the transpirable sol water fraction. The study was carried out in vineyards in the Penedès Designation of Origin, planted with Chardonnay, with different disturbance degree and with compost treated and untreated areas within the plots. The response in years with different rainfall distributions, included years with extreme situations were evaluated. The main soil types are Typic Xerorthent and Calcixerollic Xerorthent and soil is bare most of the time. Soil water content was measured at different depths using TDR probes. The transpirable soil water fraction was estimated as the ratio between available soil water (ASW) at a given date and the total transpirable soil water (TTSW). TTSW was estimated as the soil water reserve held between an upper and lower limit (respectively, the soil water content near field capacity and soil water content at the end of a dry summer) and integrated over the estimated effective rooting depth. Both minimum and maximum soil water values varied within the plot at all depths. On the surface the minimum values ranged between 4.45 to about 10%, while on deeper layers it ranged between 7.8 and 17.8%. Regarding the maximum value varied between 17.45 and 24.8%. The transpirable soil water fraction for a given year varied significantly within the plot, with differences greater than 20% between the treated and untreated areas. The results were more exacerbated in the driest years an in those with more irregular distribution. Water available has a significant effect on yield. The results indicate the need of using different strategies for water management within the plots.
Tang, Ronglin; Li, Zhao-Liang; Sun, Xiaomin; Bi, Yuyun
2017-01-01
Surface evapotranspiration (ET) is an important component of water and energy in land and atmospheric systems. This paper investigated whether using variable surface resistances in the reference ET estimates from the full-form Penman-Monteith (PM) equation could improve the upscaled daily ET estimates in the constant reference evaporative fraction (EFr, the ratio of actual to reference grass/alfalfa ET) method on clear-sky days using ground-based measurements. Half-hourly near-surface meteorological variables and eddy covariance (EC) system-measured latent heat flux data on clear-sky days were collected at two sites with different climatic conditions, namely, the subhumid Yucheng station in northern China and the arid Yingke site in northwestern China and were used as the model input and ground-truth, respectively. The results showed that using the Food and Agriculture Organization (FAO)-PM equation, the American Society of Civil Engineers-PM equation, and the full-form PM equation to estimate the reference ET in the constant EFr method produced progressively smaller upscaled daily ET at a given time from midmorning to midafternoon. Using all three PM equations produced the best results at noon at both sites regardless of whether the energy imbalance of the EC measurements was closed. When the EC measurements were not corrected for energy imbalance, using variable surface resistance in the full-form PM equation could improve the ET upscaling in the midafternoon, but worse results may occur in the midmorning to noon. Site-to-site and time-to-time variations were found in the performances of a given PM equation (with fixed or variable surface resistances) before and after the energy imbalance was closed.
Institute of Scientific and Technical Information of China (English)
Jun ZHANG; Na PENG; Xinan WANG; LI Li; Qingjiang WANG
2007-01-01
An ideal method has been established for calculating the precipitation of α2 ordered phase in near-α titanium alloys based on the theory on the critical electron concentration for the precipitation of α 2 ordered phase in near-α titanium alloys. With complete precipitation of α2 phase in near-α titanium alloys, the alloys can be considered to be composed of two parts: (1) the α2 ordered phase with the stoichiometric atomic ratio of Ti3X; (2) the disorder solid solution with the critical composition in which the α2 ordered phase is just unable to precipitate. By using this method, the volume fractions of α2 ordered phase precipitated in Ti-Al, Ti-Sn,Ti-Al-Sn-Zr alloys with various Al, Sn and/or Zr contents have been calculated. The influences of Al and Sn on the precipitation of α2 ordered phase are discussed. The calculating results show substantial agreement with the experimental ones.
Kockova, Radka; Kacer, Petr; Pirk, Jan; Maly, Jiri; Sukupova, Lucie; Sikula, Viktor; Kotrc, Martin; Barciakova, Lucia; Honsova, Eva; Maly, Marek; Kautzner, Josef; Sedmera, David; Penicka, Martin
2016-04-25
The aim of our study was to investigate the relationship between the cardiac magnetic resonance (CMR)-derived native T1 relaxation time and myocardial extracellular volume (ECV) fraction and the extent of diffuse myocardial fibrosis (DMF) on targeted myocardial left ventricular (LV) biopsy. The study population consisted of 40 patients (age 63±8 years, 65% male) undergoing valve and/or ascending aorta surgery for severe aortic stenosis (77.5%), root dilatation (7.5%) or valve regurgitation (15%). The T1 relaxation time was assessed in the basal interventricular septum pre- and 10-min post-contrast administration using the modified Look-Locker Inversion recovery sequence prior to surgery. LV myocardial biopsy specimen was obtained during surgery from the basal interventricular septal segment matched with the T1 mapping assessment. The percentage of myocardial collagen was quantified using picrosirius red staining. The average percentage of myocardial collagen was 22.0±14.8%. Both native T1 relaxation time with cutoff value ≥1,010 ms (sensitivity=90%, specificity=73%, area under the curve=0.82) and ECV with cutoff value ≥0.32 (sensitivity=80%, specificity=90%, area under the curve=0.85) showed high accuracy to identify severe (>30%) DMF. The native T1 relaxation time showed significant correlation with LV mass (P<0.01). Native T1 relaxation time and ECV at 10 min after contrast administration are accurate markers of DMF. (Circ J 2016; 80: 1202-1209).
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Fisher, R.A.; Phillips, N.E. (Lawrence Berkeley Lab., CA (United States)); Gordon, J.E. (Lawrence Berkeley Lab., CA (United States) Amherst Coll., MA (United States). Dept. of Physics)
1991-12-01
Specific-heat measurements, on polycrystalline samples of YBa{sub 2}Cu{sub 3}O{sub 7-{delta}}, YBCO, have shown sample-to-sample variations in the volume fraction of superconductivity, f{sub s}, which is correlated with the concentration of Cu{sup 2+} magnetic moments in the YBCO lattice. At low temperatures the lattice specific heat also varies with f{sub s}, but these variations do not persist above {approximately}20K. The low-temperature data show that {Theta}{sub 0}{sup {minus}3} varies linearly with f{sub 3}, and give values of 520 and 390K for {Theta}{sub o} for fully-superconducting and fully-normal'' YBCO, respectively. These results suggest that the long wavelength phonon modes are altered when Cu{sup 2+} magnetic moments are present in the lattice. The fact that different samples have the same lattice specific heat at {approximately}20K and above T{sub c} indicates that the higher energy phonon modes are insensitive to these Cu{sup 2+} moments.
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Fisher, R.A.; Phillips, N.E. [Lawrence Berkeley Lab., CA (United States); Gordon, J.E. [Lawrence Berkeley Lab., CA (United States)]|[Amherst Coll., MA (United States). Dept. of Physics
1991-12-01
Specific-heat measurements, on polycrystalline samples of YBa{sub 2}Cu{sub 3}O{sub 7-{delta}}, YBCO, have shown sample-to-sample variations in the volume fraction of superconductivity, f{sub s}, which is correlated with the concentration of Cu{sup 2+} magnetic moments in the YBCO lattice. At low temperatures the lattice specific heat also varies with f{sub s}, but these variations do not persist above {approximately}20K. The low-temperature data show that {Theta}{sub 0}{sup {minus}3} varies linearly with f{sub 3}, and give values of 520 and 390K for {Theta}{sub o} for fully-superconducting and ``fully-normal`` YBCO, respectively. These results suggest that the long wavelength phonon modes are altered when Cu{sup 2+} magnetic moments are present in the lattice. The fact that different samples have the same lattice specific heat at {approximately}20K and above T{sub c} indicates that the higher energy phonon modes are insensitive to these Cu{sup 2+} moments.
Yan, Hui; Wang, K. G.; Jones, Jim E.
2016-06-01
A parallel algorithm for large-scale three-dimensional phase-field simulations of phase coarsening is developed and implemented on high-performance architectures. From the large-scale simulations, a new kinetics in phase coarsening in the region of ultrahigh volume fraction is found. The parallel implementation is capable of harnessing the greater computer power available from high-performance architectures. The parallelized code enables increase in three-dimensional simulation system size up to a 5123 grid cube. Through the parallelized code, practical runtime can be achieved for three-dimensional large-scale simulations, and the statistical significance of the results from these high resolution parallel simulations are greatly improved over those obtainable from serial simulations. A detailed performance analysis on speed-up and scalability is presented, showing good scalability which improves with increasing problem size. In addition, a model for prediction of runtime is developed, which shows a good agreement with actual run time from numerical tests.
Hindel, Stefan; Söhner, Anika; Maaß, Marc; Sauerwein, Wolfgang; Möllmann, Dorothe; Baba, Hideo Andreas; Kramer, Martin; Lüdemann, Lutz
2017-01-01
The purpose of this study was to assess the accuracy of fractional blood volume (vb) estimates in low-perfused and low-vascularized tissue using dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). The results of different MRI methods were compared with histology to evaluate the accuracy of these methods under clinical conditions. vb was estimated by DCE-MRI using a 3D gradient echo sequence with k-space undersampling in five muscle groups in the hind leg of 9 female pigs. Two gadolinium-based contrast agents (CA) were used: a rapidly extravasating, extracellular, gadolinium-based, low-molecular-weight contrast agent (LMCA, gadoterate meglumine) and an extracellular, gadolinium-based, albumin-binding, slowly extravasating blood pool contrast agent (BPCA, gadofosveset trisodium). LMCA data were evaluated using the extended Tofts model (ETM) and the two-compartment exchange model (2CXM). The images acquired with administration of the BPCA were used to evaluate the accuracy of vb estimation with a bolus deconvolution technique (BD) and a method we call equilibrium MRI (EqMRI). The latter calculates the ratio of the magnitude of the relaxation rate change in the tissue curve at an approximate equilibrium state to the height of the same area of the arterial input function (AIF). Immunohistochemical staining with isolectin was used to label endothelium. A light microscope was used to estimate the fractional vascular area by relating the vascular region to the total tissue region (immunohistochemical vessel staining, IHVS). In addition, the percentage fraction of vascular volume was determined by multiplying the microvascular density (MVD) with the average estimated capillary lumen, [Formula: see text], where d = 8μm is the assumed capillary diameter (microvascular density estimation, MVDE). Except for ETM values, highly significant correlations were found between most of the MRI methods investigated. In the cranial thigh, for example, the vb medians
Söhner, Anika; Maaß, Marc; Sauerwein, Wolfgang; Möllmann, Dorothe; Baba, Hideo Andreas; Kramer, Martin; Lüdemann, Lutz
2017-01-01
The purpose of this study was to assess the accuracy of fractional blood volume (vb) estimates in low-perfused and low-vascularized tissue using dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). The results of different MRI methods were compared with histology to evaluate the accuracy of these methods under clinical conditions. vb was estimated by DCE-MRI using a 3D gradient echo sequence with k-space undersampling in five muscle groups in the hind leg of 9 female pigs. Two gadolinium-based contrast agents (CA) were used: a rapidly extravasating, extracellular, gadolinium-based, low-molecular-weight contrast agent (LMCA, gadoterate meglumine) and an extracellular, gadolinium-based, albumin-binding, slowly extravasating blood pool contrast agent (BPCA, gadofosveset trisodium). LMCA data were evaluated using the extended Tofts model (ETM) and the two-compartment exchange model (2CXM). The images acquired with administration of the BPCA were used to evaluate the accuracy of vb estimation with a bolus deconvolution technique (BD) and a method we call equilibrium MRI (EqMRI). The latter calculates the ratio of the magnitude of the relaxation rate change in the tissue curve at an approximate equilibrium state to the height of the same area of the arterial input function (AIF). Immunohistochemical staining with isolectin was used to label endothelium. A light microscope was used to estimate the fractional vascular area by relating the vascular region to the total tissue region (immunohistochemical vessel staining, IHVS). In addition, the percentage fraction of vascular volume was determined by multiplying the microvascular density (MVD) with the average estimated capillary lumen, π(d2)2, where d = 8μm is the assumed capillary diameter (microvascular density estimation, MVDE). Except for ETM values, highly significant correlations were found between most of the MRI methods investigated. In the cranial thigh, for example, the vb medians (interquartile range
Jalbani, Nusrat; Kazi, Tasneem Gul; Jamali, Muhammad Khan; Arain, Muhammad Balal; Afridi, Hassan Imran; Sheerazi, Syed T; Ansari, Rehana
2007-01-01
A simple and rapid method based on ultrasound energy is described for the determination of aluminum (AI) in complex matrixes of chocolate and candy samples by electrothermal atomic absorption spectrometry. The optimization strategy was carried out using multivariate methodologies. Five variables (temperature of the ultrasonic bath; exposure time to ultrasound energy; volumes of 2 acid mixtures, HNO3-H2SO4-H2O2 (1 + 1 + 1) and HNO3-H2O2 (1 + 1); and sample mass) were considered as factors in the optimization process. Interactions between analytical factors and their optimal levels were investigated using fractional factorial and Doehlert matrix designs. Validation of the ultrasonic-assisted acid digestion procedure was performed against standard reference materials, milk powder (SRM 8435) and wheat flour (SRM 1567a). The proposed procedure allowed Al determination with a detection limit of 2.3 microg/L (signal-to-noise = 3) and a precision, calculated as relative standard deviation, of 2.2% for a set of 10 measurements of certified samples. The recovery of Al by the proposed procedure was close to 100%, and no significant difference at the 95% confidence level was found between determined and certified values of Al. The proposed procedure was applied to the determination of Al in chocolate and candy samples. The results indicated that cocoa-based chocolates have higher contents of Al than milk- and sugar-based chocolates and candies.
Katugampola, Udita N.
2016-09-01
There is a debate among contemporary mathematicians about what it really means by a fractional derivative. The question arose as a consequence of introducing a 'new' definition of a fractional derivative in [1]. In a reply, Ortigueira and Machado [2] came up with several very important criteria to determine whether a given derivative is a fractional derivative. According to their criterion, the new fractional derivative, called conformable fractional derivative, introduced by Khalil et al. [1] turns out not to be a fractional derivative, but rather a controlled or conformable derivative. In proving the claim the authors in [2] use an example [2, p. 6]. It turns out that the explanation given there needs some corrections and it is the sole purpose of this note.
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Yamada Y
2013-04-01
Full Text Available Yosuke Yamada,1,2 Yoshihisa Masuo,3 Eitaro Nakamura,4 Shingo Oda5 1Laboratory of Sports and Health Science, Kyoto Prefectural University of Medicine, Kyoto, Japan; 2Japan Society for the Promotion of Science, Tokyo, Japan; 3Waseda University Research Institute for Elderly Health, Saitama, Japan; 4Department of Sport Science, Kyoto Iken College of Medicine and Health, Kyoto, Japan; 5Faculty of Health and Well-being, Kansai University, Osaka, Japan Abstract: The aim of this study was to evaluate and quantify differences in muscle distribution in athletes of various ball sports using segmental bioelectrical impedance analysis (SBIA. Participants were 115 male collegiate athletes from four ball sports (baseball, soccer, tennis, and lacrosse. Percent body fat (%BF and lean body mass were measured, and SBIA was used to measure segmental muscle volume (MV in bilateral upper arms, forearms, thighs, and lower legs. We calculated the MV ratios of dominant to nondominant, proximal to distal, and upper to lower limbs. The measurements consisted of a total of 31 variables. Cluster and factor analyses were applied to identify redundant variables. The muscle distribution was significantly different among groups, but the %BF was not. The classification procedures of the discriminant analysis could correctly distinguish 84.3% of the athletes. These results suggest that collegiate ball game athletes have adapted their physique to their sport movements very well, and the SBIA, which is an affordable, noninvasive, easy-to-operate, and fast alternative method in the field, can distinguish ball game athletes according to their specific muscle distribution within a 5-minute measurement. The SBIA could be a useful, affordable, and fast tool for identifying talents for specific sports. Keywords: discriminant analysis, cluster and factor analysis, segmental bioelectrical impedance analysis, baseball, lacrosse
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Ho, Kean F. (Academic Dept. of Radiation Oncology, Univ. of Manchester, Manchester (United Kingdom)); Fowler, Jack F. (Dept. of Human Oncology and Medical Physics, Univ. of Wisconsin, Wisconsin (United States)); Sykes, Andrew J.; Yap, Beng K.; Lee, Lip W.; Slevin, Nick J. (Dept. of Clinical Oncology, Christie Hospital NHS Foundation Trust, Manchester (United Kingdom))
2009-04-15
Introduction. Altered fractionation has demonstrated clinical benefits compared to the conventional 2 Gy/day standard of 70 Gy. When using synchronous chemotherapy, there is uncertainty about optimum fractionation. IMRT with its potential for Simultaneous Integrated Boost (SIB) adds further to this uncertainty. This survey will examine international practice of IMRT fractionation and suggest possible reasons for diversity in approach. Material and methods. Fourteen international cancer centres were surveyed for IMRT dose/fractionation practised in each centre. Results. Twelve different types of dose fractionation were reported. Conventional 70-72 Gy (daily 2 Gy/fraction) was used in 3/14 centres with concurrent chemotherapy while 11/14 centres used altered fractionation. Two centres used >1 schedule. Reported schedules and number of centres included 6 fractions/week DAHANCA regime (3), modest hypofractionation (=2.2 Gy/fraction) (3), dose-escalated hypofractionation (=2.3 Gy/fraction) (4), hyperfractionation (1), continuous acceleration (1) and concomitant boost (1). Reasons for dose fractionation variability include (i) dose escalation; (ii) total irradiated volume; (iii) number of target volumes; (iv) synchronous systemic treatment; (v) shorter overall treatment time; (vi) resources availability; (vii) longer time on treatment couch; (viii) variable GTV margins; (ix) confidence in treatment setup; (x) late tissue toxicity and (xi) use of lower neck anterior fields. Conclusions. This variability in IMRT fractionation makes any meaningful comparison of treatment results difficult. Some standardization is needed particularly for design of multi-centre randomized clinical trials.
Ohlerth, Stefanie; Bley, Carla Rohrer; Laluhová, Dagmar; Roos, Malgorzata; Kaser-Hotz, Barbara
2010-10-01
Radiation therapy does not only target tumour cells but also affects tumour vascularity. In the present study, changes in tumour vascularity and blood volume were investigated in five grade 1 oral fibrosarcomas, eight other sarcomas (non-oral soft tissue and bone sarcomas) and 12 squamous cell carcinomas in dogs during fractionated radiation therapy (total dose, 45-56 Gy). Contrast-enhanced power Doppler ultrasound was performed before fraction 1, 3, 6, 8, 10, 12, 14 and 15 or 16 (sarcomas) or 17 (squamous cell carcinomas). Prior to treatment, median vascularity and blood volume were significantly higher in squamous cell carcinomas (P=0.0005 and 0.001), whereas measurements did not differ between oral fibrosarcomas and other sarcomas (P=0.88 and 0.999). During the course of radiation therapy, only small, non-significant changes in vascularity and blood volume were observed in all three tumour histology groups (P=0.08 and P=0.213), whereas median tumour volume significantly decreased until the end of treatment (P=0.04 for fibrosarcomas and other sarcomas, P=0.008 for squamous cell carcinomas). It appeared that there was a proportional decrease in tumour volume, vascularity and blood volume. Doppler measurements did not predict progression free interval or survival in any of the three tumour groups (P=0.06-0.86). However, the number of tumours investigated was small and therefore, the results can only be considered preliminary.
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Eble, Michael J. [Dept. of Radiotherapy, RWTH Aachen (Germany); Pinkawa, Michael; Piroth, Marc D.; Fischedick, Karin; Holy, Richard; Klotz, Jens; Nussen, Sandra; Krenkel, Barbara
2009-11-15
Purpose: to evaluate the impact of the clinical target volume (CTV) and fraction dose on quality of life (QoL) after external-beam radiotherapy (EBRT) for prostate cancer. Patients and methods: a group of 283 patients has been surveyed prospectively before, at the last day, at a median time of 2 months and 15 months after EBRT (70.2-72 Gy) using a validated questionnaire (Expanded Prostate Cancer Index Composite). FBRT of prostate alone (P, n = 70) versus prostate with seminal vesicles (PS, n = 213) was compared. Differences of fraction doses (1.8 Gy, n = 80, vs. 2.0 Gy, n = 69) have been evaluated in the patient group receiving a total dose of 72 Gy. Results: significantly higher bladder and rectum volumes were found at all dose levels for the patients with PS versus P within the CTV (p < 0.001). Similar volumes resulted in the groups with different fraction doses. Paradoxically, bowel function scores decreased significantly less 2 and 15 months after EBRT of PS versus P. 2 months after EBRT, patients with a fraction dose of 2.0 Gy versus 1.8 Gy reported pain with urination ({>=} once a day in 12% vs. 3%; p = 0.04) and painful bowel movements ({>=} rarely in 46% vs. 29%; p = 0.05) more frequently. No long-term differences were found. Conclusion: the risk of adverse QoL changes after EBRT for prostate cancer cannot be derived from the dose-volume histogram alone. Seminal vesicles can be included in the CTV up to a moderate total dose without adverse effects on QoL. Apart from a longer recovery period, higher fraction doses were not associated with higher toxicity. (orig.)
Yu, Hongbin; Chin, Mian; Remer, Lorraine A.; Kleidman, Richard G.; Bellouin, Nicolas; Bian, Huisheng; Diehl, Thomas
2009-01-01
In this study, we examine seasonal and geographical variability of marine aerosol fine-mode fraction (f(sub m)) and its impacts on deriving the anthropogenic component of aerosol optical depth (tau(sub a)) and direct radiative forcing from multispectral satellite measurements. A proxy of f(sub m), empirically derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) Collection 5 data, shows large seasonal and geographical variations that are consistent with the Goddard Chemistry Aerosol Radiation Transport (GOCART) and Global Modeling Initiative (GMI) model simulations. The so-derived seasonally and spatially varying f(sub m) is then implemented into a method of estimating tau(sub a) and direct radiative forcing from the MODIS measurements. It is found that the use of a constant value for fm as in previous studies would have overestimated Ta by about 20% over global ocean, with the overestimation up to 45% in some regions and seasons. The 7-year (2001-2007) global ocean average tau(sub a) is 0.035, with yearly average ranging from 0.031 to 0.039. Future improvement in measurements is needed to better separate anthropogenic aerosol from natural ones and to narrow down the wide range of aerosol direct radiative forcing.
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Peixoto, Philippe Netto Belache
2016-07-01
This study presents a methodology based on the principles of gamma ray attenuation to identify volume fractions in biphasic systems composed of oil-gas-water and gas which are found in the offshore oil industry. This methodology is based on the acknowledgment counts per second on the photopeak energy using a detection system composed of a NaI (Tl) detector, a source of {sup 137}Cs without collimation positioned at 180 ° relative to the detector on a smooth stratified flow regime. The mathematical modeling for computational simulation using the code MCNP-X was performed using the experimental measurements of the detector characteristics (energy resolution and efficiency), characteristics of the material water and oil (density and coefficient attenuation) and measurement of the volume fractions. To predict these fractions were used artificial neural networks (ANNs), and to obtain an adequate training the ANNs for the prediction of volume fractions were simulated a larger number of volume fractions in MCNP-X. The experimental data were used in the set data necessary for validation of ANNs and the data generated using the computer code MCNP-X were used in training and test sets of the ANNs. Were used ANNs of type feed-forward Multilayer Perceptron (MLP) and analyzed two functions of training, Levenberg-Marquardt (LM) and gradient descent with momentum (GDM), both using the Backpropagation training algorithm. The ANNs identified correctly the volume fractions of the multiphase system with mean relative errors lower than 1.21 %, enabling the application of this methodology for this purpose. (author)
Measuring of Volume Fraction for SiC Particles in SiCP/Al Composite%SiC颗粒增强铝基复合材料中SiC颗粒体积分数的测定
Institute of Scientific and Technical Information of China (English)
木二珍; 李强
2013-01-01
利用金相法和XRD定量分析法对SiC颗粒增强铝基复合材料的SiC颗粒体积分数进行测定.用定量金相法测得SiC增强铝基复合材料SiC颗粒的体积分数为58.6％,用XRD定量分析法测得的体积分数为62.7％.%The volume fraction for SiC particle was measured by metallographic method and XRD quantitative analysis.The volume fraction for SiC particles is 56.1％ for metallographic method and 62.7％ for XRD quantitative analysis.
Lee, Hye-Jeong; Im, Dong Jin; Youn, Jong-Chan; Chang, Suyon; Suh, Young Joo; Hong, Yoo Jin; Kim, Young Jin; Hur, Jin; Choi, Byoung Wook
2016-07-01
Purpose To evaluate the feasibility of equilibrium contrast material-enhanced dual-energy cardiac computed tomography (CT) to determine extracellular volume fraction (ECV) in nonischemic cardiomyopathy (CMP) compared with magnetic resonance (MR) imaging. Materials and Methods This study was approved by the institutional review board; informed consent was obtained. Seven healthy subjects and 23 patients (six with hypertrophic CMP, nine with dilated CMP, four with amyloidosis, and four with sarcoidosis) (mean age ± standard deviation, 57.33 years ± 14.82; 19 male participants [63.3%]) were prospectively enrolled. Twelve minutes after contrast material injection (1.8 mL/kg at 3 mL/sec), dual-energy cardiac CT was performed. ECV was measured by two observers independently. Hematocrit levels were compared between healthy subjects and patients with the Mann-Whitney U test. In per-subject analysis, interobserver agreement for CT was assessed with the intraclass correlation coefficient (ICC), and intertest agreement between MR imaging and CT was assessed with Bland-Altman analysis. In per-segment analysis, Student t tests in the linear mixed model were used to compare ECV on CT images between healthy subjects and patients. Results Hematocrit level was 43.44% ± 1.80 for healthy subjects and 41.23% ± 5.61 for patients with MR imaging (P = .16) and 43.50% ± 1.92 for healthy subjects and 41.35% ± 5.92 for patients with CT (P = .15). For observer 1 in per-subject analysis, ECV was 34.18% ± 8.98 for MR imaging and 34.48% ± 8.97 for CT. For observer 2, myocardial ECV was 34.42% ± 9.03 for MR imaging and 33.98% ± 9.05 for CT. Interobserver agreement for ECV at CT was excellent (ICC = 0.987). Bland-Altman analysis between MR imaging and CT showed a small bias (-0.06%), with 95% limits of agreement of -1.19 and 1.79. Compared with healthy subjects, patients with hypertrophic CMP, dilated CMP, amyloidosis, and sarcoidosis had significantly higher myocardial ECV at dual
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Jensen, Christoph J. [Elisabeth Hospital Essen, Department of Cardiology and Angiology, Essen (Germany); Duke University Medical Center, Duke Cardiovascular Magnetic Resonance Center, Durham, NC (United States); Wolf, Alexander; Eberle, Holger C.; Sabin, Georg V.; Bruder, Oliver [Elisabeth Hospital Essen, Department of Cardiology and Angiology, Essen (Germany); Forsting, Michael; Nassenstein, Kai; Lauenstein, Thomas C.; Schlosser, Thomas [University Hospital Essen, Department of Diagnostic and Interventional Radiology and Neuroradiology, Essen (Germany)
2011-12-15
To evaluate the accuracy and variability of right ventricular (RV) volumes and mass using dual-source computed tomography (DSCT) and the influence of slice orientation in comparison to cardiac magnetic resonance imaging (CMR). In 33 patients undergoing cardiac DSCT and CMR, RV parameters were calculated using the short-axis (DSCT, CMR) and axial orientation (DSCT). Intra- and interobserver variability were assessed by Bland-Altman analysis. Short-axis orientation: RV parameters of the two techniques were not statistically different. Axial orientation: RV volumes and mass were significantly overestimated compared with short-axis parameters whereas EF was similar. The short-axis approach resulted in low variability, although the axial orientation had the least amount of intra- and interobserver variability. RV parameters can be more accurately assessed by DSCT compared with CMR using short-axis slice orientation. RV volumes and mass are significantly higher using axial compared with short-axis slices, whereas EF is unaffected. RV parameters derived from both approaches yield high reproducibility. (orig.)
Variability of Gross Tumor Volume in Nasopharyngeal Carcinoma Using 11C-Choline and 18F-FDG PET/CT.
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Jun Jiang
Full Text Available This study was conducted to evaluate the variability of gross tumor volume (GTV using 11C-Choline and 18F-FDG PET/CT images for nasopharyngeal carcinomas boundary definition. Assessment consisted of inter-observer and inter-modality variation analysis. Four radiation oncologists were invited to manually contour GTV by using PET/CT fusion obtained from a cohort of 12 patients with nasopharyngeal carcinoma (NPC and who underwent both 11C-Choline and 18F-FDG scans. Student's paired-sample t-test was performed for analyzing inter-observer and inter-modality variability. Semi-automatic segmentation methods, including thresholding and region growing, were also validated against the manual contouring of the two types of PET images. We observed no significant variation in the results obtained by different oncologists in terms of the same type of PET/CT volumes. Choline fusion volumes were significantly larger than the FDG volumes (p < 0.0001, mean ± SD = 18.21 ± 8.19. While significantly consistent results were obtained between the oncologists and the standard references in Choline volumes compared with those in FDG volumes (p = 0.0025. Simple semi-automatic delineation methods indicated that 11C-Choline PET images could provide better results than FDG volumes (p = 0.076, CI = [-0.29, 0.025]. 11C-Choline PET/CT may be more advantageous in GTV delineation for the radiotherapy of NPC than 18F-FDG. Phantom simulations and clinical trials should be conducted to prove the possible improvement of the treatment outcome.
Alipour, Habibollah; Karimipour, Arash; Safaei, Mohammad Reza; Semiromi, Davood Toghraie; Akbari, Omid Ali
2017-04-01
This study aimed at exploring influence of T-semi attached rib on the turbulent flow and heat transfer parameters of a silver-water nanofluid with different volume fractions in a three-dimensional trapezoidal microchannel. For this purpose, convection heat transfer of the silver-water nanofluid in a ribbed microchannel was numerically studied under a constant heat flux on upper and lower walls as well as isolated side walls. Calculations were done for a range of Reynolds numbers between 10,000 and 16,000, and in four different sorts of serrations with proportion of rib width to hole of serration width (R/W). The results of this research are presented as the coefficient of friction, Nusselt number, heat transfer coefficient and thermal efficiency, four different R/W microchannels. The results of numerical modeling showed that the fluid's convection heat transfer coefficient is increased as the Reynolds number and volume fraction of solid nanoparticle are increased. For R/W=0.5, it was also maximum for all the volume fractions of nanoparticle and different Reynolds numbers in comparison to other similar R/W situations. That's while friction coefficient, pressure drop and pumping power is maximum for serration with R/W=0 compared to other serration ratios which lead to decreased fluid-heat transfer performance.
Selkirk, Henry B.; Molod, Andrea M.
2014-01-01
Large-scale models such as GEOS-5 typically calculate grid-scale fractional cloudiness through a PDF parameterization of the sub-gridscale distribution of specific humidity. The GEOS-5 moisture routine uses a simple rectangular PDF varying in height that follows a tanh profile. While below 10 km this profile is informed by moisture information from the AIRS instrument, there is relatively little empirical basis for the profile above that level. ATTREX provides an opportunity to refine the profile using estimates of the horizontal variability of measurements of water vapor, total water and ice particles from the Global Hawk aircraft at or near the tropopause. These measurements will be compared with estimates of large-scale cloud fraction from CALIPSO and lidar retrievals from the CPL on the aircraft. We will use the variability measurements to perform studies of the sensitivity of the GEOS-5 cloud-fraction to various modifications to the PDF shape and to its vertical profile.
Hamill, Neil; Yeo, Lami; Romero, Roberto; Hassan, Sonia S.; Myers, Stephen A.; Mittal, Pooja; Kusanovic, Juan Pedro; Balasubramaniam, Mamtha; Chaiworapongsa, Tinnakorn; Vaisbuch, Edi; Espinoza, Jimmy; Gotsch, Francesca; Goncalves, Luis F.; Lee, Wesley
2011-01-01
Objective To quantify fetal cardiovascular parameters with Spatio-Temporal Image Correlation (STIC) and Virtual Organ Computed-aided AnaLysis (VOCAL™) utilizing the sub-feature: “Contour Finder: Trace”. Study Design A cross-sectional study was designed consisting of patients with normal pregnancies between 19 and 40 weeks of gestation. After STIC datasets were acquired, analysis was performed offline (4DView) and the following cardiovascular parameters were evaluated: ventricular volume in end systole and end diastole, stroke volume, cardiac output, and ejection fraction. To account for fetal size, cardiac output was also expressed as a function of head circumference, abdominal circumference, or femoral diaphysis length. Regression models were fitted for each cardiovascular parameter to assess the effect of gestational age and paired comparisons were made between the left and right ventricles. Results 1) Two hundred and seventeen patients were retrospectively identified, of whom 184 had adequate STIC datasets (85% acceptance); 2) ventricular volume, stroke volume, cardiac output, and adjusted cardiac output increased with gestational age; whereas, the ejection fraction decreased as gestation advanced; 3) the right ventricle was larger than the left in both systole (Right: 0.50 ml, IQR: 0.2 – 0.9; vs. Left: 0.27 ml, IQR: 0.1 – 0.5; p<0.001) and diastole (Right: 1.20 ml, IQR: 0.7 – 2.2; vs. Left: 1.03 ml, IQR: 0.5 – 1.7; p<0.001); 4) there were no differences between the left and right ventricle with respect to stroke volume, cardiac output, or adjusted cardiac output; and 5) the left ventricular ejection fraction was greater than the right (Left: 72.2%, IQR: 64 – 78; vs. Right: 62.4%, IQR: 56 – 69; p<0.001). Conclusion Fetal echocardiography, utilizing STIC and VOCAL™ with the sub-feature: “Contour Finder: Trace”, allows assessment of fetal cardiovascular parameters. Normal fetal cardiovascular physiology is characterized by ventricular
Kamakura, Miho; Maruyama, Ryoko
2016-10-01
A high glycemic status increases the risk for autonomic dysfunction and cardiovascular failure. The aim of this study was to investigate time-dependent changes in the autonomic response and cardiovascular dynamics and the association between the level of hemoglobin A1c (HbA1c) and autonomic response during blood volume reduction. The study population consisted of 26 preoperative participants who were scheduled for autologous blood donation (200-400 mL of whole blood) for intraoperative or postoperative use. These participants without circulatory, respiratory, or brain disease and diabetes mellitus were grouped according to their HbA1c levels: blood pressure (BP) and analyzed heart rate variability (HRV) to quantify cardiac autonomic regulation throughout blood donation. During blood volume reduction, which was about 10% of the circulating blood volume, the BP and heart rate varied within normal ranges in both groups. The high-frequency (HF) component, an index of parasympathetic nerve activity, and the ratio of low-frequency (LF) to HF components (LF/HF), an index of sympathetic nerve activity, significantly decreased and increased with the progression of blood volume reduction, respectively, in the HbA1c blood volume reduction only in the HbA1c blood volume reduction.
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Taghavi R.
2006-12-01
Full Text Available A method is introduced for the automatic decomposition of time-varying volumes such as those encountered in engine FEA and CFD. Examples of the application of this method to all-hexahedral mesh generation are also presented. Une méthode est ici proposée pour la décomposition automatique. de volumes instationnaires tels que ceux rencontrés dans les moteurs en calculs de structure en élément finis ou de mécanique de fluides. Des exemples d'application de cette méthode à la génération de maillages en hexahèdre sont présentés.
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Alberto Giannoni
Full Text Available BACKGROUND: Clinicians are sometimes advised to make decisions using thresholds in measured variables, derived from prognostic studies. OBJECTIVES: We studied why there are conflicting apparently-optimal prognostic thresholds, for example in exercise peak oxygen uptake (pVO2, ejection fraction (EF, and Brain Natriuretic Peptide (BNP in heart failure (HF. DATA SOURCES AND ELIGIBILITY CRITERIA: Studies testing pVO2, EF or BNP prognostic thresholds in heart failure, published between 1990 and 2010, listed on Pubmed. METHODS: First, we examined studies testing pVO2, EF or BNP prognostic thresholds. Second, we created repeated simulations of 1500 patients to identify whether an apparently-optimal prognostic threshold indicates step change in risk. RESULTS: 33 studies (8946 patients tested a pVO2 threshold. 18 found it prognostically significant: the actual reported threshold ranged widely (10-18 ml/kg/min but was overwhelmingly controlled by the individual study population's mean pVO2 (r = 0.86, p<0.00001. In contrast, the 15 negative publications were testing thresholds 199% further from their means (p = 0.0001. Likewise, of 35 EF studies (10220 patients, the thresholds in the 22 positive reports were strongly determined by study means (r = 0.90, p<0.0001. Similarly, in the 19 positives of 20 BNP studies (9725 patients: r = 0.86 (p<0.0001. Second, survival simulations always discovered a "most significant" threshold, even when there was definitely no step change in mortality. With linear increase in risk, the apparently-optimal threshold was always near the sample mean (r = 0.99, p<0.001. LIMITATIONS: This study cannot report the best threshold for any of these variables; instead it explains how common clinical research procedures routinely produce false thresholds. KEY FINDINGS: First, shifting (and/or disappearance of an apparently-optimal prognostic threshold is strongly determined by studies' average pVO2, EF or BNP. Second
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Tang, Robert Y., E-mail: rx-tang@laurentian.ca [Biomolecular Sciences Program, Laurentian University, 935 Ramsey Lake Road, Sudbury, Ontario P3E 2C6 (Canada); McDonald, Nancy, E-mail: mcdnancye@gmail.com; Laamanen, Curtis, E-mail: cx-laamanen@laurentian.ca [Department of Physics, Laurentian University, 935 Ramsey Lake Road, Sudbury, Ontario P3E 2C6 (Canada); LeClair, Robert J., E-mail: rleclair@laurentian.ca [Department of Physics, Laurentian University, 935 Ramsey Lake Road, Sudbury, Ontario P3E 2C6, Canada and Biomolecular Sciences Program, Laurentian University, 935 Ramsey Lake Road, Sudbury, Ontario P3E 2C6 (Canada)
2014-11-01
Purpose: To develop a method to estimate the mean fractional volume of fat (ν{sup ¯}{sub fat}) within a region of interest (ROI) of a tissue sample for wide-angle x-ray scatter (WAXS) applications. A scatter signal from the ROI was obtained and use of ν{sup ¯}{sub fat} in a WAXS fat subtraction model provided a way to estimate the differential linear scattering coefficient μ{sub s} of the remaining fatless tissue. Methods: The efficacy of the method was tested using animal tissue from a local butcher shop. Formalin fixed samples, 5 mm in diameter 4 mm thick, were prepared. The two main tissue types were fat and meat (fibrous). Pure as well as composite samples consisting of a mixture of the two tissue types were analyzed. For the latter samples, ν{sub fat} for the tissue columns of interest were extracted from corresponding pixels in CCD digital x-ray images using a calibration curve. The means ν{sup ¯}{sub fat} were then calculated for use in a WAXS fat subtraction model. For the WAXS measurements, the samples were interrogated with a 2.7 mm diameter 50 kV beam and the 6° scattered photons were detected with a CdTe detector subtending a solid angle of 7.75 × 10{sup −5} sr. Using the scatter spectrum, an estimate of the incident spectrum, and a scatter model, μ{sub s} was determined for the tissue in the ROI. For the composite samples, a WAXS fat subtraction model was used to estimate the μ{sub s} of the fibrous tissue in the ROI. This signal was compared to μ{sub s} of fibrous tissue obtained using a pure fibrous sample. Results: For chicken and beef composites, ν{sup ¯}{sub fat}=0.33±0.05 and 0.32 ± 0.05, respectively. The subtractions of these fat components from the WAXS composite signals provided estimates of μ{sub s} for chicken and beef fibrous tissue. The differences between the estimates and μ{sub s} of fibrous obtained with a pure sample were calculated as a function of the momentum transfer x. A t-test showed that the mean of the
Tang, Robert Y; McDonald, Nancy; Laamanen, Curtis; LeClair, Robert J
2014-11-01
To develop a method to estimate the mean fractional volume of fat (ν¯fat) within a region of interest (ROI) of a tissue sample for wide-angle x-ray scatter (WAXS) applications. A scatter signal from the ROI was obtained and use of ν¯fat in a WAXS fat subtraction model provided a way to estimate the differential linear scattering coefficient μs of the remaining fatless tissue. The efficacy of the method was tested using animal tissue from a local butcher shop. Formalin fixed samples, 5 mm in diameter 4 mm thick, were prepared. The two main tissue types were fat and meat (fibrous). Pure as well as composite samples consisting of a mixture of the two tissue types were analyzed. For the latter samples, νfat for the tissue columns of interest were extracted from corresponding pixels in CCD digital x-ray images using a calibration curve. The means ν¯fat were then calculated for use in a WAXS fat subtraction model. For the WAXS measurements, the samples were interrogated with a 2.7 mm diameter 50 kV beam and the 6° scattered photons were detected with a CdTe detector subtending a solid angle of 7.75 × 10(-5) sr. Using the scatter spectrum, an estimate of the incident spectrum, and a scatter model, μs was determined for the tissue in the ROI. For the composite samples, a WAXS fat subtraction model was used to estimate the μs of the fibrous tissue in the ROI. This signal was compared to μs of fibrous tissue obtained using a pure fibrous sample. For chicken and beef composites, ν¯fat=0.33±0.05 and 0.32 ± 0.05, respectively. The subtractions of these fat components from the WAXS composite signals provided estimates of μs for chicken and beef fibrous tissue. The differences between the estimates and μs of fibrous obtained with a pure sample were calculated as a function of the momentum transfer x. A t-test showed that the mean of the differences did not vary from zero in a statistically significant way thereby validating the methods. The methodology to
Flueck, Joelle Leonie; Schaufelberger, Fabienne; Lienert, Martina; Schäfer Olstad, Daniela; Wilhelm, Matthias; Perret, Claudio
2016-01-01
Caffeine increases sympathetic nerve activity in healthy individuals. Such modulation of nervous system activity can be tracked by assessing the heart rate variability. This study aimed to investigate the influence of caffeine on time- and frequency-domain heart rate variability parameters, blood pressure and tidal volume in paraplegic and tetraplegic compared to able-bodied participants. Heart rate variability was measured in supine and sitting position pre and post ingestion of either placebo or 6 mg caffeine in 12 able-bodied, 9 paraplegic and 7 tetraplegic participants in a placebo-controlled, randomized and double-blind study design. Metronomic breathing was applied (0.25 Hz) and tidal volume was recorded during heart rate variability assessment. Blood pressure, plasma caffeine and epinephrine concentrations were analyzed pre and post ingestion. Most parameters of heart rate variability did not significantly change post caffeine ingestion compared to placebo. Tidal volume significantly increased post caffeine ingestion in able-bodied (p = 0.021) and paraplegic (p = 0.036) but not in tetraplegic participants (p = 0.34). Systolic and diastolic blood pressure increased significantly post caffeine in able-bodied (systolic: p = 0.003; diastolic: p = 0.021) and tetraplegic (systolic: p = 0.043; diastolic: p = 0.042) but not in paraplegic participants (systolic: p = 0.09; diastolic: p = 0.33). Plasma caffeine concentrations were significantly increased post caffeine ingestion in all three groups of participants (p<0.05). Plasma epinephrine concentrations increased significantly in able-bodied (p = 0.002) and paraplegic (p = 0.032) but not in tetraplegic participants (p = 0.63). The influence of caffeine on the autonomic nervous system seems to depend on the level of lesion and the extent of the impairment. Therefore, tetraplegic participants may be less influenced by caffeine ingestion. Trial Registration ClinicalTrials.gov NCT02083328 PMID:27776149
Schulz, Stefan M; Ayala, Erica; Dahme, Bernhard; Ritz, Thomas
2009-11-01
Respiratory sinus arrhythmia (RSA) is a common estimator of vagal outflow to the heart, dependent on parasympathetic activity. During variable breathing, both respiration rate and tidal volume contribute substantially to within-individual RSA variance. A respiratory control method allows for within-individual correction of the time-domain index of RSA. rsaToolbox is a set of MATLAB programs for scoring respiration-corrected RSA using measurements of cardiac interbeat intervals, respiratory-cycle times, and tidal volumes, recorded at different paced-breathing frequencies. The within-individual regression of RSA divided by tidal volume upon total respiratory cycle time is then used to estimate the baseline vagal tone for each breath of a given total respiratory-cycle time. During a subsequent analysis, the difference between the observed RSA (divided by the tidal volume at each breath) and the RSA divided by the tidal volume that was predicted by the baseline equation serves as an estimate of changes in vagal tone. rsaToolbox includes a graphical user interface for intuitive handling. Modular implementation of the algorithm also allows for flexible integration within other analytic strategies or for batch processing.
Miyake, Y.; Hozumi, T; Mori, I.; Sugioka, K; Yamamuro, A; Akasaka, T; Homma, S; Yoshida, K.; Yoshikawa, J
2002-01-01
Background: The recently introduced automated cardiac flow measurement (ACM) technique provides a quick and an accurate automated calculation of stroke volume and cardiac output. This is obtained by spatio-temporal integration of digital Doppler velocity profile data.
Institute of Scientific and Technical Information of China (English)
吴福飞; 董双快; 宫经伟; 陈亮亮; 李东生; 侍克斌
2016-01-01
Powers theory proposes calculation method for the pure volume of cement hydration products, which does not apply to calculate the volume of cementitious materials with mineral admixture. The formula of cementitious materials volume was proposed that based on the basic principles of cement and mineral admixture hydration, and the proposed method of reliability was verified by the results of Powers theoretical model and volume fraction of cement hydration products. On this basis, the factor such as water-cement ratio, the ratio of admixture and types was further researched for the volumes of cementitious materials hydration products. Mixture in test were designed 2 water-cement ratio (0.30 and 0.40, respectively), two content (20% and 60%, respectively) of mineral admixture, and 3 kinds of mineral admixture (lithium slag, fly ash and steel slag, respectively), forming paste that was stirred according with the designed ratio in 5 mL centrifuge tube in a blender and curing to 1, 7, 14, 28, 60 and 90 d in curing room (temperature was (20±1)℃, humidity was not less than 95%), and then testing reaction extent of cement and mineral admixture (such as fly ash, steel slag. lithium slag) according with the chemical bound water and HCl dissolution method. The results showed that hydration extent of lithium slag, fly ash and steel slag at 28d decreased by 46.63%, 69.56% and 74.82% (P<0.05) when mineral admixture content varied from 20% to 60% and water-cement ratio was 0.30. Hydration extent of cement at 28 d was increased by 7.25% when water-cement ratio increased from 0.30 to 0.40. When mineral admixture content varied from 20% to 60%, hydration extent of lithium slag, fly ash and steel slag at 28 d increased by 24.14% 18.56%, 17.61% and 8.84%, 12.21%, and 29.37% (P<0.05), respectively. In contrast, the influence of the mineral admixture content was bigger than water-cement ratio for the hydration extent of composite cementitious materials. In different water-cement ratio
Wattanakrai, Penpun; Pootongkam, Suwimon; Rojhirunsakool, Salinee
2012-04-01
Ablative and fractional lasers are used for periorbital rejuvenation, with different downtime, side effects, and efficacy. To compare effects of fractional 1,550-nm ytterbium- and erbium-doped (Yb/Er) fiber laser and variable square pulse (VSP) 2,940-nm erbium-doped yttrium aluminum garnet (Er:YAG) laser treatment for periorbital wrinkles. This side-by-side comparison study randomized 22 women with mild to moderate periorbital rhytides to receive three treatments with fractional 1,550-nm Yb/Er fiber laser or 2,940-nm Er:YAG laser treatment on either side at 4-week intervals. A video camera was used for objective assessment of wrinkles. Standardized photographs, patient satisfaction, side effects, and pain score were recorded. Twenty subjects completed the study. The median change in wrinkle measurement 3 months after laser treatments from baseline of the fractional Yb/Er fiber laser side was -3.03 versus -3.09 on the VSP Er:YAG side (p = .63, Wilcoxon signed-rank test). There was no significant difference in degree of wrinkle improvement analyzed according to global assessment between the sides (p = .25, Wilcoxon signed-rank test). Less downtime correlated with greater patient satisfaction of the fractional laser treatment . Two subjects experienced hyperpigmentation. Fractional Yb/Er fiber and VSP Er:YAG lasers are effective in improving periorbital wrinkles in Asians, with minimal side effects. © 2012 by the American Society for Dermatologic Surgery, Inc. Published by Wiley Periodicals, Inc.
García González, Miguel Ángel; Ramos Castro, Juan José; Fernández Chimeno, Mireya
2012-01-01
The study aims to present and interpret a novel index based on fractional calculus ( αc) and to assess differences in RR time series dynamics in subjects during meditation. Fractional differintegration (FDI) of a RR time series provides a new time series.αc is defined as the order of the FDI operator that provides the time series with minimum variance. Analyzed time series were obtained from the Exaggerated Heart Rate Oscillations During Two Meditation Techniques database. This da...
-Dimensional Fractional Lagrange's Inversion Theorem
Directory of Open Access Journals (Sweden)
F. A. Abd El-Salam
2013-01-01
Full Text Available Using Riemann-Liouville fractional differential operator, a fractional extension of the Lagrange inversion theorem and related formulas are developed. The required basic definitions, lemmas, and theorems in the fractional calculus are presented. A fractional form of Lagrange's expansion for one implicitly defined independent variable is obtained. Then, a fractional version of Lagrange's expansion in more than one unknown function is generalized. For extending the treatment in higher dimensions, some relevant vectors and tensors definitions and notations are presented. A fractional Taylor expansion of a function of -dimensional polyadics is derived. A fractional -dimensional Lagrange inversion theorem is proved.
Savander, V. I.; Shumskiy, B. E.; Pinegin, A. A.
2016-12-01
The possibility of decreasing the vapor fraction at the VVER-1200 fuel assembly outlet by shaping the axial power density field is considered. The power density field was shaped by axial redistribution of the concentration of the burnable gadolinium poison in the Gd-containing fuel rods. The mathematical modeling of the VVER-1200 core was performed using the NOSTRA computer code.
Karras, G; Billard, F; Lavorel, B; Siour, G; Hartmann, J -M; Faucher, O; Gershnabel, Erez; Prior, Yehiam; Averbukh, Ilya Sh
2016-01-01
We report the observation of fractional echoes in a double-pulse excited nonlinear system. Unlike standard echoes which appear periodically at delays which are integer multiple of the delay between the two exciting pulses, the fractional echoes appear at rational fractions of this delay. We discuss the mechanism leading to this phenomenon, and provide the first experimental demonstration of fractional echoes by measuring third harmonic generation in a thermal gas of CO2 molecules excited by a pair of femtosecond laser pulses.
Maria Klimikova
2010-01-01
Understanding the reasons of the present financial problems lies In understanding the substance of fractional reserve banking. The substance of fractional banking is in lending more money than the bankers have. Banking of partial reserves is an alternative form which links deposit banking and credit banking. Fractional banking is causing many unfavorable economic impacts in the worldwide system, specifically an inflation.
Maria Klimikova
2010-01-01
Understanding the reasons of the present financial problems lies In understanding the substance of fractional reserve banking. The substance of fractional banking is in lending more money than the bankers have. Banking of partial reserves is an alternative form which links deposit banking and credit banking. Fractional banking is causing many unfavorable economic impacts in the worldwide system, specifically an inflation.
Institute of Scientific and Technical Information of China (English)
赖家美; 陈显明; 王德盼; 鄢冬冬; 王科
2014-01-01
Effects of the size of infusion media on resin flow behavior,fiber volume fraction distribution and void content in vacuum assisted resin transfer molding(VARTM) were studied.The results showed that with the increase of infusion media size, the resin flow rate increased exponentially;the fiber volume fraction showed a tendency to increase after the first decrease,and the infusion media boundary was just the high and low fiber volume fraction line;the void content increased first and then decreased and increased tremendously at last,varied from 3.86% to 19.92%.%研究了导流介质尺寸对真空辅助树脂传递模塑(VARTM)工艺中树脂流动行为的影响，以及对复合材料制品中纤维分布和空隙率的影响。结果表明，随着导流介质尺寸的增加，树脂在增强体中的流动速度加快，并呈现指数加速趋势；制品中纤维体积含量呈现先减少后增大的趋势，并且以导流介质边界为纤维体积含量高低的分界线；复合材料制品的空隙率范围在3.86%～19.92%，空隙率呈现先增大后减小再加速增大的趋势。
Institute of Scientific and Technical Information of China (English)
鞠彦忠; 王德弘; 李秋晨; 贾玉琢; 肖琦
2011-01-01
Basic mechanical properties such as compressive strength, splitting tensile strength and flexural strength of reactive powder concrete were experimentally investigated.The influence of steel fiber volume fraction on mechanical properties of RPC was analyzed.A fitted relation expression between flexural strength and splitting tensile strength was obtained.A mathematical expression for compressive stress-strain curve of reactive powder concrete was established for different steel fiber volume fractions based on experimental analysis.Results show that compressive strength, splitting tensile strength and flexural strength of reactive powder concrete specimens increase along with the steel fiber content increase when the steel fiber volume fraction is in the range from 1.0 ％ to 3.5 ％.When the steel fiber volume fraction is higher than 3.5％, its compressive strength decreases, the splitting tensile strength increases slightly, however, its flexural strength increases obviously.%通过实验研究了活性粉末混凝土的基本力学性能(杭压强度、劈拉强度和杭折强度),分析了钢纤维掺量对活性粉末混凝土力学性能的影响,拟合得到了杭折强度与劈拉强度之间的关系表达式.在实验分析的基础上,建立了不同钢纤维体积含量活性粉末混凝土受压应力-应变全曲线的数学表达式.研究结果表明:钢纤维体积含量在1.0%～3.5%之间时,活性粉末混凝土的抗压强度、臂拉强度和抗折强度均随着钢纤维掺量的增加而增大;当钢纤维体积含量超过3.5%后,活性粉末混凝土杭压强度下降,臂拉强度略有提高,而杭折强度仍有明显的提高.
DEFF Research Database (Denmark)
Mogensen, O.; Sørensen, Flemming Brandt; Bichel, P.
1999-01-01
We evaluated the following nine parameters with respect to their prognostic value in females with endometrial cancer: four stereologic parameters [mean nuclear volume (MNV), nuclear volume fraction, nuclear index and mitotic index], the immunohistochemical expression of cancer antigen (CA125...
Povstenko, Yuriy
2015-01-01
This book is devoted to fractional thermoelasticity, i.e. thermoelasticity based on the heat conduction equation with differential operators of fractional order. Readers will discover how time-fractional differential operators describe memory effects and space-fractional differential operators deal with the long-range interaction. Fractional calculus, generalized Fourier law, axisymmetric and central symmetric problems and many relevant equations are featured in the book. The latest developments in the field are included and the reader is brought up to date with current research. The book contains a large number of figures, to show the characteristic features of temperature and stress distributions and to represent the whole spectrum of order of fractional operators. This work presents a picture of the state-of-the-art of fractional thermoelasticity and is suitable for specialists in applied mathematics, physics, geophysics, elasticity, thermoelasticity and engineering sciences. Corresponding sections of ...
A study of X-ray volume imaging system in image guided radiotherapy with variable gantry rotations
Directory of Open Access Journals (Sweden)
NVN Madhusudhana Sresty
2016-03-01
Full Text Available Purpose: The main purpose of this work is to investigate the optimal usage of X-ray volume imaging (XVI system in image-guided radiotherapy with different gantry rotations in order to reduce scanning volume.Methods: A total of 60 scans of 16 individual patients with breast and head and neck cancer were used in this study. Full and partial gantry rotations were performed at the same time with same setup on the couch using XVI system by changing the preset information. The reference and localization images were matched with this system. The set up errors were evaluated with XVI software.Results: Variation in translational errors with full and half gantry rotations in breast cases were <2 mm in 86.6% of measurements. Similarly, variations between full and partial gantry rotations in head and neck cases were <1 mm in 95.5% of measurements. Results showed almost similar translational and rotational shifts in both full and partial gantry rotations in the majority of the cases.Conclusion: Based on selected cases in this study, partial rotation of the gantry for acquiring 3D cone beam computerized tomography (CBCT is very useful option in reducing scanning volume and total treatment time in IGRT. However, the use of partial rotation of the gantry depends on patient thickness and area to be reconstructed to track anatomical changes near to the target.
Franzin, Alberto; Panni, Pietro; Spatola, Giorgio; Vecchio, Antonella Del; Gallotti, Alberto L; Gigliotti, Carmen R; Cavalli, Andrea; Donofrio, Carmine A; Mortini, Pietro
2016-12-01
OBJECTIVE There are few reported series regarding volume-staged Gamma Knife radiosurgery (GKRS) for the treatment of large, complex, cerebral arteriovenous malformations (AVMs). The object of this study was to report the results of using volume-staged Gamma Knife radiosurgery for patients affected by large and complex AVMs. METHODS Data from 20 patients with large AVMs were prospectively included in the authors' AVM database between 2004 and 2012. A staging strategy was used when treating lesion volumes larger than 10 cm(3). Hemorrhage and seizures were the presenting clinical feature for 6 (30%) and 8 (40%) patients, respectively. The median AVM volume was 15.9 cm(3) (range 10.1-34.3 cm(3)). The mean interval between stages (± standard deviation) was 15 months (± 9 months). The median margin dose for each stage was 20 Gy (range 18-25 Gy). RESULTS Obliteration was confirmed in 8 (42%) patients after a mean follow-up of 45 months (range 19-87 months). A significant reduction (> 75%) of the original nidal volume was achieved in 4 (20%) patients. Engel Class I-II seizure status was reported by 75% of patients presenting with seizures (50% Engel Class I and 25% Engel Class II) after radiosurgery. After radiosurgery, 71.5% (5/7) of patients who had presented with a worsening neurological deficit reported a complete resolution or amelioration. None of the patients who presented acutely because of hemorrhage experienced a new bleeding episode during follow-up. One (5%) patient developed radionecrosis that caused sensorimotor hemisyndrome. Two (10%) patients sustained a bleeding episode after GKRS, although only 1 (5%) was symptomatic. High nidal flow rate and a time interval between stages of less than 11.7 months were factors significantly associated with AVM obliteration (p = 0.021 and p = 0.041, respectively). Patient age younger than 44 years was significantly associated with a greater than 75% reduction in AVM volume but not with AVM obliteration (p = 0
Caricchi, Luca; Simpson, Guy; Schaltegger, Urs
2016-04-01
Magma fluxes in the Earth's crust play an important role in regulating the relationship between the frequency and magnitude of volcanic eruptions, the chemical evolution of magmatic systems and the distribution of geothermal energy and mineral resources on our planet. Therefore, quantifying magma productivity and the rate of magma transfer within the crust can provide valuable insights to characterise the long-term behaviour of volcanic systems and to unveil the link between the physical and chemical evolution of magmatic systems and their potential to generate resources. We performed thermal modelling to compute the temperature evolution of crustal magmatic intrusions with different final volumes assembled over a variety of timescales (i.e., at different magma fluxes). Using these results, we calculated synthetic populations of zircon ages assuming the number of zircons crystallising in a given time period is directly proportional to the volume of magma at temperature within the zircon crystallisation range. The statistical analysis of the calculated populations of zircon ages shows that the mode, median and standard deviation of the populations varies coherently as function of the rate of magma injection and final volume of the crustal intrusions. Therefore, the statistical properties of the population of zircon ages can add useful constraints to quantify the rate of magma injection and the final volume of magmatic intrusions. Here, we explore the effect of different ranges of zircon saturation temperature, intrusion geometry, and wall rock temperature on the calculated distributions of zircon ages. Additionally, we determine the effect of undersampling on the variability of mode, median and standards deviation of calculated populations of zircon ages to estimate the minimum number of zircon analyses necessary to obtain meaningful estimates of magma flux and final intrusion volume.
Directory of Open Access Journals (Sweden)
Luca eCaricchi
2016-04-01
Full Text Available Magma fluxes in the Earth’s crust play an important role in regulating the relationship between the frequency and magnitude of volcanic eruptions, the chemical evolution of magmatic systems and the distribution of geothermal energy and mineral resources on our planet. Therefore, quantifying magma productivity and the rate of magma transfer within the crust can provide valuable insights to characterise the long-term behaviour of volcanic systems and to unveil the link between the physical and chemical evolution of magmatic systems and their potential to generate resources. We performed thermal modelling to compute the temperature evolution of crustal magmatic intrusions with different final volumes assembled over a variety of timescales (i.e., at different magma fluxes. Using these results, we calculated synthetic populations of zircon ages assuming the number of zircons crystallising in a given time period is directly proportional to the volume of magma at temperature within the zircon crystallisation range. The statistical analysis of the calculated populations of zircon ages shows that the mode, median and standard deviation of the populations varies coherently as function of the rate of magma injection and final volume of the crustal intrusions. Therefore, the statistical properties of the population of zircon ages can add useful constraints to quantify the rate of magma injection and the final volume of magmatic intrusions.Here, we explore the effect of different ranges of zircon saturation temperature, intrusion geometry, and wall rock temperature on the calculated distributions of zircon ages. Additionally, we determine the effect of undersampling on the variability of mode, median and standards deviation of calculated populations of zircon ages to estimate the minimum number of zircon analyses necessary to obtain meaningful estimates of magma flux and final intrusion volume.
Ortiz, Héctor; Biondo, Sebastiano; Codina, Antonio; Ciga, Miguel Á; Enríquez-Navascués, José M; Espín, Eloy; García-Granero, Eduardo; Roig, José Vicente
2016-01-01
This multicentre observational study examines variation between hospitals in postoperative mortality after elective surgery in the Rectal Cancer Project of the Spanish Society of Surgeons and explores whether hospital volume and patient characteristics contribute to any variation between hospitals. Hospital variation was quantified using a multilevel approach on prospective data derived from the multicentre database of all rectal adenocarcinomas operated by an anterior resection or an abdominoperineal excision at 84 surgical departments from 2006 to 2013. The following variables were included in the analysis; demographics, American Society of Anaesthesiologists classification, tumour location and stage, administration of neoadjuvant treatment, and annual volume of surgical procedures. A total of 9809 consecutive patients were included. The rate of 30-day postoperative mortality was 1.8% Stratified by annual surgical volume hospitals varied from 1.4 to 2.0 in 30-day mortality. In the multilevel regression analysis, male gender (OR 1.623 [1.143; 2.348]; P<.008), increased age (OR: 5.811 [3.479; 10.087]; P<.001), and ASA score (OR 10.046 [3.390; 43.185]; P<.001) were associated with 30-day mortality. However, annual surgical volume was not associated with mortality (OR 1.309 [0.483; 4.238]; P=.619). Besides, there was a statistically significant variation in mortality between all departments (MOR 1.588 [1.293; 2.015]; P<.001). Postoperative mortality varies significantly among hospitals included in the project and this difference cannot be attributed to the annual surgical volume. Copyright © 2015 AEC. Publicado por Elsevier España, S.L.U. All rights reserved.
2007-11-02
49017-3084 CH I CHANGE NO. 1 DoD 4100.39-M DoD 4100.39-M Volume 9 V DLSC- VPH 1 July 1997 _-’ FEDERAL LOGISTICS INFORMATION SYSTEM (FLIS) PROCEDURES...47 3053 UNIT OF ISSUE CONVERSION FACTOR 0005N H 02 QS 8472 FORMER UNIT OF ISSUE 0002A H 89 0211 OCCURS COUNTER/li/ 0001N H GV 2862 PHRASE CODE...16 0707 MANAGEMENT CONTROL DATA, COAST GUARD 0007X H 16 0443 EXPANSION FIELD 1 0001X H 47 3053 UNIT OF ISSUE CONVERSION FACTOR 0005N H 02 0S 8472
Johnson, Kenneth L.; White, K, Preston, Jr.
2012-01-01
The NASA Engineering and Safety Center was requested to improve on the Best Practices document produced for the NESC assessment, Verification of Probabilistic Requirements for the Constellation Program, by giving a recommended procedure for using acceptance sampling by variables techniques. This recommended procedure would be used as an alternative to the potentially resource-intensive acceptance sampling by attributes method given in the document. This document contains the outcome of the assessment.
Energy Technology Data Exchange (ETDEWEB)
Hoej Christensen, A.; Olsen, Hans; Drivsholm, C.
2012-02-15
The report describes a concept for renovating older existing Constant Air Volume (CAV) ventilation systems to modulating low-cost Variable Air Volume (VAV) systems. The concept is based on the total ventilated area being divided into appropriate indoor climate zones, which can cover from one to several offices with similar climate needs. For this initial climate assessment two relatively ''simple'' tools were developed that can estimate the temperature level in one room from the ventilation airflow, heat loads, etc.: - BSimFast (24-hour mean temperature calculation according to SBI-196, 2000); - BSimLight (Temperature simulation based on Danvak Textbook of Heat and Climate Technology). The concept of 'one room' can also be extended to 'one zone' with appropriate assumptions. However, only one mean room temperature is calculated. The different climate zones were equipped with Halton HFB control unit at the air supply and exhaust side. The project the following feedback options were used: - HFB unit's damper opening degree (0 to 90 degrees); - HFB unit's current flow; - HFB unit's exhaust temperature; and feedback from: - Frequency transformer (fan speed); - The central static duct pressure at the ventilation unit. In the project a control algorithm is developed that ensures a robust control of the entire ventilation system without adverse cyclic variations, based among other things on the exhaust temperature for each climate zone, and with the requirement that at least one throttle valve is always at least 80% open. It turned out that information on the current partial air volumes was necessary in addition to the individual throttle settings. Otherwise, a cyclic variations could not be controlled..Thus, it was the exhaust temperature from individual climate zones that defined the respective volumes of air. The concept was implemented on a complete CAV system and on part of a large CAV system, respectively. (LN)
Meaney, Christopher; Moineddin, Rahim
2014-01-24
In biomedical research, response variables are often encountered which have bounded support on the open unit interval--(0,1). Traditionally, researchers have attempted to estimate covariate effects on these types of response data using linear regression. Alternative modelling strategies may include: beta regression, variable-dispersion beta regression, and fractional logit regression models. This study employs a Monte Carlo simulation design to compare the statistical properties of the linear regression model to that of the more novel beta regression, variable-dispersion beta regression, and fractional logit regression models. In the Monte Carlo experiment we assume a simple two sample design. We assume observations are realizations of independent draws from their respective probability models. The randomly simulated draws from the various probability models are chosen to emulate average proportion/percentage/rate differences of pre-specified magnitudes. Following simulation of the experimental data we estimate average proportion/percentage/rate differences. We compare the estimators in terms of bias, variance, type-1 error and power. Estimates of Monte Carlo error associated with these quantities are provided. If response data are beta distributed with constant dispersion parameters across the two samples, then all models are unbiased and have reasonable type-1 error rates and power profiles. If the response data in the two samples have different dispersion parameters, then the simple beta regression model is biased. When the sample size is small (N0 = N1 = 25) linear regression has superior type-1 error rates compared to the other models. Small sample type-1 error rates can be improved in beta regression models using bias correction/reduction methods. In the power experiments, variable-dispersion beta regression and fractional logit regression models have slightly elevated power compared to linear regression models. Similar results were observed if the
Energy Technology Data Exchange (ETDEWEB)
Schweighardt, F.K.; Kingsley, I.S.; Cooper, F.E.; Kamzelski, A.Z.; Parees, D.M.
1983-09-01
A data analysis was performed to determine the relationship between the Wilsonville Solvent Quality test result and SRC liquefaction process parameters. The data base studied covers the years 1979 to 1982, Wilsonville runs 133 to 234. Only process-defined material balance data sets were included to best represent steady-state operation. Each material balance period provided 48 variables from which common process conditions were selected by imposing a range of acceptable deviations from a norm, e.g., a reactor hydrogen pressure of 2000 +- 100 psi. Data for all variables vs. solvent quality were plotted, and in some cases variables were compared with each other to determine common trends, e.g. gas production vs. hydrogen consumption. The plotted data produced no discernible trends. Separating the data by coal type (mine location) and identifying common process conditions with coal types still provided no absolute correlations with solvent quality. However, the effect of the weight percent pyrite present in the feed coal produced a consistent trend. A coal containing more than 1.2% pyrite and less than 0.1% sulfate sulfur yielded results in which any one correlation would cluster about a central point. It was observed that, on average, Kentucky Fies and Pyro mine coal and Indiana V coal clustered together, while Kentucky Lafayette and Dotiki mine coals clustered together. These data point clusters for the variables tested were nearly independent of reactor pressure, space rate, and temperature. One unusual observation of all the data points, independent of process conditions, was that at each change of feed coal, the sum of hydrocarbon and heteroatom gas production was greatest for the first 30 days, after which gas production reached a steady state dependent on process conditions, primarily temperature.
Institute of Scientific and Technical Information of China (English)
刘明鼎; 张艳敏
2014-01-01
对一类变系数时间分数阶延迟微分方程给出了一种有限差分解法，将对时间的一阶导数利用α(0＜α＜1)阶导数来代替，同时证明了该格式的收敛性与稳定性，数值算例验证该方法有效。%A numerical method was given to solve a time fractional delay differential equation with variable coefficients, which the first order derivative was replaced by a fractional derivative of order α(0<α<1). Furthermore, we also prove the difference scheme is unconditional stable and unconditional convergence. Numerical example shows that the numerical method is a practical method.
Wunsch, Carl; Stammer, Detlef
1995-01-01
Two years of altimetric data from the TOPEX/POSEIDON spacecraft have been used to produce preliminary estimates of the space and time spectra of global variability for both sea surface height and slope. The results are expressed in terms of both degree variances from spherical harmonic expansions and in along-track wavenumbers. Simple analytic approximations both in terms of piece-wise power laws and Pade fractions are provided for comparison with independent measurements and for easy use of the results. A number of uses of such spectra exist, including the possibility of combining the altimetric data with other observations, predictions of spatial coherences, and the estimation of the accuracy of apparent secular trends in sea level.
Ethanol-gasoline volume fraction estimation of vehicles%车用乙醇汽油体积分数估计
Institute of Scientific and Technical Information of China (English)
郑太雄; 王波; 李永福; 陈琳
2015-01-01
为获得精确的乙醇体积分数，在发动机进气模型的基础上，设计了高增益观测器估计歧管压力，并对观测器误差进行了收敛性和稳定性分析。设计PI控制器对空燃比进行控制，使过量空气系数趋于理论值。利用PI控制器输出的燃油反馈信号，通过积分清零运算得出化学计量空燃比（Rs ），根据 Rs 与乙醇体积分数的关系计算得出乙醇体积分数估计值。仿真结果表明：乙醇体积分数估计时间在2s以内，估计误差绝对值小于1％，满足汽车的排放性和经济性要求。%For acquiring a precise estimation of ethanol proportion , based on the engine air charge model ,the high gain observer was designed to estimate the manifold absolute pressure ,and property of convergence and stability were analyzed to the observer errors .PI controller was proposed to con‐trol the air to fuel ratio ,which compelled the excess air coefficient to the theoretical value .After‐wards ,the fuel feedback signal from the PI control was utilized ,and the stoichiometric air‐to‐fuel rati‐o (Rs ) was achieved through the integral zero clearing operation .At last ,ethanol volume fracrion es‐timation value was calculated based on the relationship between the Rs and the ethanol volume fracri‐on .Simulation results show that the estimated time of the ethanol volume fracrion is within 2 s ,and the absolute value of the estimated error is less than 1% ,w hich meets the emissions and fuel economy of the vehicles .
Energy Technology Data Exchange (ETDEWEB)
Eliazar, Iddo I., E-mail: eliazar@post.tau.ac.il [Holon Institute of Technology, P.O. Box 305, Holon 58102 (Israel); Shlesinger, Michael F., E-mail: mike.shlesinger@navy.mil [Office of Naval Research, Code 30, 875 N. Randolph St., Arlington, VA 22203 (United States)
2013-06-10
Brownian motion is the archetypal model for random transport processes in science and engineering. Brownian motion displays neither wild fluctuations (the “Noah effect”), nor long-range correlations (the “Joseph effect”). The quintessential model for processes displaying the Noah effect is Lévy motion, the quintessential model for processes displaying the Joseph effect is fractional Brownian motion, and the prototypical model for processes displaying both the Noah and Joseph effects is fractional Lévy motion. In this paper we review these four random-motion models–henceforth termed “fractional motions” –via a unified physical setting that is based on Langevin’s equation, the Einstein–Smoluchowski paradigm, and stochastic scaling limits. The unified setting explains the universal macroscopic emergence of fractional motions, and predicts–according to microscopic-level details–which of the four fractional motions will emerge on the macroscopic level. The statistical properties of fractional motions are classified and parametrized by two exponents—a “Noah exponent” governing their fluctuations, and a “Joseph exponent” governing their dispersions and correlations. This self-contained review provides a concise and cohesive introduction to fractional motions.
Van Hoof, Thibaut; Piérard, Olivier; Lani, Frédéric
2007-04-01
In the framework of the European project PROHIPP (New design and manufacturing processes for high pressure fluid power product — NMP 2-CT-2004-50546), CENAERO develops a library of constitutive models used to predict the mechanical response of a family of cast iron. The present contribution focuses on one particular microstructure, corresponding to a ferrite matrix containing spheroidal graphite and isolated inclusions of pearlite. An incremental mean field homogenisation scheme such as the one developed by Doghri and Ouaar is used. In the present application, the ferrite matrix is described by a Gurson type constitutive law (porous plasticity) while the pearlite inclusions are assumed to obey the classical isotropic J2 plasticity. The predictions of the micromechanical model are compared to the results of Finite Element simulations performed on three-dimensional representative volume elements (RVEs).
Energy Technology Data Exchange (ETDEWEB)
Zhang, Q.; Johnson, E.V.; Djeridane, Y.; Abramov, A.; Roca i Cabarrocas, P. [LPICM-CNRS, Ecole Polytechnique, Palaiseau (France)
2008-08-15
Microcrystalline silicon thin film pin solar cells with a highly crystallized intrinsic {mu}c-Si:F:H absorber were prepared by RF-plasma enhanced chemical vapour deposition using SiF{sub 4} as the gas precursor. The cells were produced with a vacuum break between the doped layer and intrinsic layer depositions, and the effect of different subsequent interface treatment processes was studied. The use of an intrinsic {mu}c-Si:H p/i buffer layer before the first air break increased the short circuit current density from 22.3 mA/cm{sup 2} to 24.7 mA/cm{sup 2}. However, the use of a hydrogen-plasma treatment after both air breaks without an interface buffer layer improved both the open circuit voltage and the fill factor. Although the material used for the absorber layer showed a very high crystalline fraction and thus an increased spectral response at long wavelengths, an open-circuit voltage (V{sub OC}) of 0.523 V was nevertheless observed. Such a value of V{sub OC} is higher than is typically obtained in devices that employ a highly crystallized absorber as reported in the literature (see abstract figure). Using a hydrogen-plasma treatment, a single junction {mu}c-Si:F:H pin solar cell with an efficiency of 8.3% was achieved. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)
Energy Technology Data Exchange (ETDEWEB)
Hadermann, A. F.
1985-04-09
Soluble polymers are fractionated according to molecular weight by cryogenically comminuting the polymer and introducing the polymer particles, while still in the active state induced by cryogenic grinding, into a liquid having a solvent power selected to produce a coacervate fraction containing high molecular weight polymer species and a dilute polymer solution containing lower molecular weight polymer species. The coacervate may be physically separated from the solution and finds use in the production of antimisting jet fuels and the like.
Huang, Shengli; Ramirez, Carlos; Conway, Scott; Kennedy, Kama; Kohler, Tanya; Liu, Jinxun
2016-01-01
High-resolution site index (SI) and mean annual increment (MAI) maps are desired for local forest management. We integrated field inventory, Landsat, and ecological variables to produce 30 m SI and MAI maps for the Tahoe National Forest (TNF) where different tree species coexist. We converted species-specific SI using adjustment factors. Then, the SI map was produced by (i) intensifying plots to expand the training sets to more climatic, topographic, soil, and forest reflective classes, (ii) using results from a stepwise regression to enable a weighted imputation that minimized the effects of outlier plots within classes, and (iii) local interpolation and strata median filling to assign values to pixels without direct imputations. The SI (reference age is 50 years) map had an R2 of 0.7637, a root-mean-square error (RMSE) of 3.60, and a mean absolute error (MAE) of 3.07 m. The MAI map was similarly produced with an R2 of 0.6882, an RMSE of 1.73, and a MAE of 1.20 m3·ha−1·year−1. Spatial patterns and trends of SI and MAI were analyzed to be related to elevation, aspect, slope, soil productivity, and forest type. The 30 m SI and MAI maps can be used to support decisions on fire, plantation, biodiversity, and carbon.
Hahn, Ezra; Jiang, Haiyan; Ng, Angela; Bashir, Shaheena; Ahmed, Sameera; Tsang, Richard; Sun, Alexander; Gospodarowicz, Mary; Hodgson, David
2017-08-01
Mediastinal radiation therapy (RT) for Hodgkin lymphoma (HL) is associated with late cardiotoxicity, but there are limited data to indicate which dosimetric parameters are most valuable for predicting this risk. This study investigated which whole heart dosimetric measurements provide the most information regarding late cardiotoxicity, and whether coronary artery dosimetry was more predictive of this outcome than whole heart dosimetry. A random sample of 125 HL patients treated with mediastinal RT was selected, and 3-dimensional cardiac dose-volume data were generated from historical plans using validated methods. Cardiac events were determined by linking patients to population-based datasets of inpatient and same-day hospitalizations and same-day procedures. Variables collected for the whole heart and 3 coronary arteries included the following: Dmean, Dmax, Dmin, dose homogeneity, V5, V10, V20, and V30. Multivariable competing risk regression models were generated for the whole heart and coronary arteries. There were 44 cardiac events documented, of which 70% were ischemic. The best multivariable model included the following covariates: whole heart Dmean (hazard ratio [HR] 1.09, P=.0083), dose homogeneity (HR 0.94, P=.0034), male sex (HR 2.31, P=.014), and age (HR 1.03, P=.0049). When any adverse cardiac event was the outcome, models using coronary artery variables did not perform better than models using whole heart variables. However, in a subanalysis of ischemic cardiac events only, the model using coronary artery variables was superior to the whole heart model and included the following covariates: age (HR 1.05, Pcoronary artery models. However, when events were limited to ischemic cardiotoxicity, the coronary artery-based model was superior. Copyright © 2017 Elsevier Inc. All rights reserved.
Directory of Open Access Journals (Sweden)
Parovik Roman I.
2016-09-01
Full Text Available The paper deals with the model of variable-order nonlinear hereditary oscillator based on a numerical finite-difference scheme. Numerical experiments have been carried out to evaluate the stability and convergence of the difference scheme. It is argued that the approximation, stability and convergence are of the first order, while the scheme is stable and converges to the exact solution.
Energy Technology Data Exchange (ETDEWEB)
Vieira, Marcelo L.C.; Nomura, Cesar H.; Tranchesi Junior, Bernardino; Oliveira, Wercules A. de; Naccarato, Gustavo; Serpa, Bruna S.; Cury, Alexandre; Passos, Rodrigo B.D.; Nobrega, Marcel V. da; Funari, Marcelo B.G.; Pfefermam, Abhaham; Makdisse, Marcia; Fischer, Claudio H.; Morhy, Samira S., E-mail: luiz766@terra.com.br [Hospital Israelita Albert Einstein, Sao Paulo, SP (Brazil)
2008-10-15
Background and objective: Few studies addressed the comparison between real-time 3D echocardiography (RT3DE) and cardiac computed tomography (CCT) concerning left ventricular ejection fraction and volumes assessment. We sought to compare both techniques regarding left ventricle (LV) ejection fraction function and volumes analysis. Methods: we studied by RT3DE (Philips IE 33, And, MA, USA) and by CCT (Toshiba, 64-slice, Otawara, Japan) 41 consecutive patients (29 males, 58 ± 11 yrs). We analysed by both techniques LVEF, LVEDV, LVESV. RT3DE and CCT data were compared by coefficients of determination (r: Pearson), Bland and Altman test and linear regression, 95% CI. Results: RT3DE data: LVEF ranged from 56.7 to 78.9 % (65.3 + 5.7 ); LVEDV ranged from 49.6 to 178.2 (88 + 27.5) mL; LVESV from 11.4 to 78 ( 33.9 + 13.7) mL. CCT data: LVEF ranged from 53 to 86 % (67.3 + 7.9 ); LVEDV ranged from 51 to 186 (106.4 + 30.7) mL; LVESV from 7 to 72 ( 35.1 + 13.8) mL. Correlations relative to RT3DE and CCT were: LVEF (r: 0. 7877, p<0.0001, 95 % CI 0.6327 to 0.8853 ); LVEDV (r:0.7671, p<0.0001, 95 % CI 0.5974 to 0.8745); LVESV (r: 0.8121, p<0.0001, 95 % CI 0.6659 to 0.8957). Conclusions: it was observed adequate correlation between real-time 3D echocardiography and cardiac computed tomography concerning ejection fraction and volumes assessment. (author)
Energy Technology Data Exchange (ETDEWEB)
Yoo, Yeon Hwa; Kim, Hak Sun; Lee, Young Han [Dept. of Radiology, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul (Korea, Republic of); and others
2015-10-15
To assess whether multi-echo Dixon magnetic resonance (MR) imaging with simultaneous T2{sup *} estimation and correction yields more accurate fat-signal fraction (FF) measurement of the lumbar paravertebral muscles, in comparison with non-T2{sup *}-corrected two-echo Dixon or T2{sup *}-corrected three-echo Dixon, using the FF measurements from single-voxel MR spectroscopy as the reference standard. Sixty patients with low back pain underwent MR imaging with a 1.5T scanner. FF mapping images automatically obtained using T2{sup *}-corrected Dixon technique with two (non-T2{sup *}-corrected), three, and six echoes, were compared with images from single-voxel MR spectroscopy at the paravertebral muscles on levels L4 through L5. FFs were measured directly by two radiologists, who independently drew the region of interest on the mapping images from the three sequences. A total of 117 spectroscopic measurements were performed either bilaterally (57 of 60 subjects) or unilaterally (3 of 60 subjects). The mean spectroscopic FF was 14.3 ± 11.7% (range, 1.9-63.7%). Interobserver agreement was excellent between the two radiologists. Lin's concordance correlation between the spectroscopic findings and all the imaging-based FFs were statistically significant (p < 0.001). FFs obtained from the T2*-corrected six-echo Dixon sequences showed a significantly better concordance with the spectroscopic data, with its concordance correlation coefficient being 0.99 and 0.98 (p < 0.001), as compared with two- or three-echo methods. T2{sup *}-corrected six-echo Dixon sequence would be a better option than two- or three-echo methods for noninvasive quantification of lumbar muscle fat quantification.
Understanding Multiplication of Fractions.
Sweetland, Robert D.
1984-01-01
Discussed the use of Cuisenaire rods in teaching the multiplication of fractions. Considers whole number times proper fraction, proper fraction multiplied by proper fraction, mixed number times proper fraction, and mixed fraction multiplied by mixed fractions. (JN)
Jerome, N. P.; d'Arcy, J. A.; Feiweier, T.; Koh, D.-M.; Leach, M. O.; Collins, D. J.; Orton, M. R.
2016-12-01
The bi-exponential intravoxel-incoherent-motion (IVIM) model for diffusion-weighted MRI (DWI) fails to account for differential T 2 s in the model compartments, resulting in overestimation of pseudodiffusion fraction f. An extended model, T2-IVIM, allows removal of the confounding echo-time (TE) dependence of f, and provides direct compartment T 2 estimates. Two consented healthy volunteer cohorts (n = 5, 6) underwent DWI comprising multiple TE/b-value combinations (Protocol 1: TE = 62-102 ms, b = 0-250 mm-2s, 30 combinations. Protocol 2: 8 b-values 0-800 mm-2s at TE = 62 ms, with 3 additional b-values 0-50 mm-2s at TE = 80, 100 ms scanned twice). Data from liver ROIs were fitted with IVIM at individual TEs, and with the T2-IVIM model using all data. Repeat-measures coefficients of variation were assessed for Protocol 2. Conventional IVIM modelling at individual TEs (Protocol 1) demonstrated apparent f increasing with longer TE: 22.4 ± 7% (TE = 62 ms) to 30.7 ± 11% (TE = 102 ms) T2-IVIM model fitting accounted for all data variation. Fitting of Protocol 2 data using T2-IVIM yielded reduced f estimates (IVIM: 27.9 ± 6%, T2-IVIM: 18.3 ± 7%), as well as T 2 = 42.1 ± 7 ms, 77.6 ± 30 ms for true and pseudodiffusion compartments, respectively. A reduced Protocol 2 dataset yielded comparable results in a clinical time frame (11 min). The confounding dependence of IVIM f on TE can be accounted for using additional b/TE images and the extended T2-IVIM model.
DEFF Research Database (Denmark)
Therkelsen, Susette Krohn; Groenning, Bjoern Aaris; Svendsen, Jesper Hastrup;
2005-01-01
. Intraobserver variability and inter-study reproducibility of the cardiac volumes and ejection fractions (EF) gave acceptable Bland-Altman plots, good correlations (R2: 0.80-0.99), and low reproducibility coefficients. The mean atrial volumes were similar in the two groups with AF [systolic vol. index (SVI): 75...
Energy Technology Data Exchange (ETDEWEB)
Mancini, Marcello; Liuzzi, Raffaele [CNR, Napoli (Italy). Istituto di biostrutture e bioimmagini; Daniele, Stefania; Raffio, Teresa; Salvatore, Marco [Napoli Univ., Napoli (Italy). Dipartimento di diagnostica per immagini; Sabbatini, Massimo; Cianciaruso, Bruno [Napoli Univ., Napoli (Italy). Istituto di nefrologia medica; Ferrara, Liberato Aldo [Napoli Univ., Napoli (Italy). Dipartimento di medicina clinica e sperimentale
2005-04-01
Purpose: Aim of the presents study was to evaluate the repeatability and reproducibility of the Doppler Resistive Index (R.I.) and the Ultrasound renal volume measurement in renal transplants. Materials and methods: Twenty -six consecutive patients (18 men, 8 women) mean age of 42,8{+-}12,4 years (M{+-}SD)(range 22-65 years) were studied twice by each of two trained sonographers using a color Doppler ultrasound scanner. Twelve of them had a normal allograft function (defined as stable serum creatinine levels {<=}123,76 {mu}mol/L), whilst the remaining 14 had decreased allograft function (serum creatinine 132.6-265.2 {mu}mol/L). Results were given as mean of 6 measurements performed at upper, middle and lower pole of the kidney. Intra- and interobserver variability was assessed by the repeatability coefficient and coefficient of variation (CV). Results: Regarding Resistive Index measurement, repeatability coefficient was between 0.04 and 0.06 and the coefficient of variation was <5%. The analysis of the Student's test did not show any significant difference between the measurements (t=0.15; p=0.87 n.s.). A good reproducibility was also detected in US measurements of renal length and volume. Conclusions: These results suggest that Color Doppler Resistive Index measurements of renal allograft and Ultrasound renal volume measurements are repeatable and reproducible. [Italian] Scopo: Valutare la ripetibilit� e la riproducibilit� delle misurazioni ecografiche dell'Indice di Resistenza (I.R.) e del volume del rene trapiantato. Materiale e metodi: Ventisei pazienti (18 uomini, 8 donne) con et� media di 42,8{+-}12,4 anni (M{+-}SD)(range 22-65 anni) sono stati studiati consecutivamente due volte con eco-color-Doppler da due ecografisti esperti. Dodici pazienti avevano funzione renale normale (livello serico di creatina stabilmente {<=}123,76 {mu}mol/L, i rimanenti 14 avevano una lieve e stabile disfunzione del rene trapiantato (creatina serica 132.6-265.2 {mu
Chakraborty, Parthasarathi; Chakraborty, Sucharita; Jayachandran, Saranya; Madan, Ritu; Sarkar, Arindam; Linsy, P; Nath, B Nagender
2016-10-01
This study describes the effect of varying bottom-water oxygen concentration on geochemical fractionation (operational speciation) of Cu and Pb in the underneath sediments across the oxygen minimum zone (Arabian Sea) in the west coast of India. Both, Cu and Pb were redistributed among the different binding phases of the sediments with changing dissolved oxygen level (from oxic to hypoxic and close to suboxic) in the bottom water. The average lability of Cu-sediment complexes gradually decreased (i.e., stability increased) with the decreasing dissolved oxygen concentrations of the bottom water. Decreasing bottom-water oxygen concentration increased Cu association with sedimentary organic matter. However, Pb association with Fe/Mn-oxyhydroxide phases in the sediments gradually decreased with the decreasing dissolved oxygen concentration of the overlying bottom water (due to dissolution of Fe/Mn oxyhydroxide phase). The lability of Pb-sediment complexes increased with the decreasing bottom-water oxygen concentration. This study suggests that bottom-water oxygen concentration is one of the key factors governing stability and lability of Cu and Pb complexes in the underneath sediment. Sedimentary organic matter and Fe/Mn oxyhydroxide binding phases were the major hosting phases for Cu and Pb respectively in the study area. Increasing lability of Pb-complexes in bottom sediments may lead to positive benthic fluxes of Pb at low oxygen environment. Copyright © 2016 Elsevier B.V. All rights reserved.
Nordon, R.; Behar, E.; Drake, S. A.
2013-01-01
Elemental abundance effects in active coronae have eluded our understanding for almost three decades, since the discovery of the first ionization potential (FIP) effect on the sun. The goal of this paper is to monitor the same coronal structures over a time interval of six days and resolve active regions on a stellar corona through rotational modulation. We report on four iso-phase X-ray spectroscopic observations of the RS CVn binary EI Eri with XMM-Newton, carried out approximately every two days, to match the rotation period of EI Eri. We present an analysis of the thermal and chemical structure of the EI Eri corona as it evolves over the six days. Although the corona is rather steady in its temperature distribution, the emission measure and FIP bias both vary and seem to be correlated. An active region, predating the beginning of the campaign, repeatedly enters into our view at the same phase as it rotates from beyond the stellar limb. As a result, the abundances tend slightly, but consistently, to increase for high FIP elements (an inverse FIP effect) with phase. We estimate the abundance increase of high FIP elements in the active region to be of about 75% over the coronal mean. This observed fractionation of elements in an active region on time scales of days provides circumstantial clues regarding the element enrichment mechanism of non-flaring stellar coronae.
Fractional Processes and Fractional-Order Signal Processing Techniques and Applications
Sheng, Hu; Qiu, TianShuang
2012-01-01
Fractional processes are widely found in science, technology and engineering systems. In Fractional Processes and Fractional-order Signal Processing, some complex random signals, characterized by the presence of a heavy-tailed distribution or non-negligible dependence between distant observations (local and long memory), are introduced and examined from the ‘fractional’ perspective using simulation, fractional-order modeling and filtering and realization of fractional-order systems. These fractional-order signal processing (FOSP) techniques are based on fractional calculus, the fractional Fourier transform and fractional lower-order moments. Fractional Processes and Fractional-order Signal Processing: • presents fractional processes of fixed, variable and distributed order studied as the output of fractional-order differential systems; • introduces FOSP techniques and the fractional signals and fractional systems point of view; • details real-world-application examples of FOSP techniques to demonstr...
Kiris, Cetin; Kwak, Dochan
1995-01-01
The fractional step and the pseudocompressibility methods for the solution of the incompressible Navier-Stokes equations are outlined. The fractional step method is based on finite-volume formulation and uses the pressure and the volume fluxes across the faces of each cell as dependent variables. The momentum equations are solved implicitly and the Poisson equation for the pressure is solved by using the multigrid method. The pseudocompressibility approach uses an implicit-higher-order-upwind differencing scheme for the convective terms together with the Gauss-Seidel line relaxation method. The dependent variables in the pseudocompressibility approach are the pressure and the cartesian velocity components in unstaggered mesh orientation. The 90-degree square duct flow, the wing-tip vortex wake flow and unsteady turbulent flows over an oscillating NACA 0015 airfoil are computed using both the fractional step and the pseudocompressibility methods. The results obtained from two different schemes are compared against experimental measurements.
Financial Planning with Fractional Goals
Goedhart, M.H.; Spronk, Jaap
1995-01-01
textabstractWhen solving financial planning problems with multiple goals by means of multiple objective programming, the presence of fractional goals leads to technical difficulties. In this paper we present a straightforward interactive approach for solving such linear fractional programs with multiple goal variables. The approach is illustrated by means of an example in financial planning.
Energy Technology Data Exchange (ETDEWEB)
Frey, H. Christopher [North Carolina State University, Raleigh, NC (United States); Tran, Loan K. [North Carolina State University, Raleigh, NC (United States)
1999-04-30
This is Volume 2 of a two-volume set of reports describing work conducted at North Carolina State University sponsored by Grant Number DE-FG05-95ER30250 by the U.S. Department of Energy. The title of the project is “Quantitative Analysis of Variability and Uncertainty in Acid Rain Assessments.” The work conducted under sponsorship of this grant pertains primarily to two main topics: (1) development of new methods for quantitative analysis of variability and uncertainty applicable to any type of model; and (2) analysis of variability and uncertainty in the performance, emissions, and cost of electric power plant combustion-based NO_{x} control technologies. These two main topics are reported separately in Volumes 1 and 2.
Bhattacharyya, Sonalee; Namakshi, Nama; Zunker, Christina; Warshauer, Hiroko K.; Warshauer, Max
2016-01-01
Making math more engaging for students is a challenge that every teacher faces on a daily basis. These authors write that they are constantly searching for rich problem-solving tasks that cover the necessary content, develop critical-thinking skills, and engage student interest. The Mystery Fraction activity provided here focuses on a key number…
Bhattacharyya, Sonalee; Namakshi, Nama; Zunker, Christina; Warshauer, Hiroko K.; Warshauer, Max
2016-01-01
Making math more engaging for students is a challenge that every teacher faces on a daily basis. These authors write that they are constantly searching for rich problem-solving tasks that cover the necessary content, develop critical-thinking skills, and engage student interest. The Mystery Fraction activity provided here focuses on a key number…
Institute of Scientific and Technical Information of China (English)
王志刚; 杨美传; 蒙星宇
2015-01-01
为研究可变容积气室在AMESim气动模型中的应用，在分析引入可变容积气室的建模方法的机理的基础上，建立了CCB II制动机电空控制单元中均衡风缸控制模块的两个气动模型。通过仿真对比分析引入可变容积气室后均衡风缸内气体压力、三通阀阀芯位移、可变容积气室体积的变化。仿真结果表明引入可变容积气室来反映阀内腔体等气体容积变化的实际情况，使建立的仿真模型更加科学，而引入可变容积气室的建模方法是可行的。%In order to study the application of variable volume pneumatic chamber in AMESim pneumatic model, two models of Equalizing Reservoir Control Portion, which are one of the pneumatic components of Electro-Pneumatic Control Unit of CCB II brake control system, are established based on the analysis of the mechanism of modeling method of applying variable volume pneumatic chamber. Through simu-lation of the two models, the air pressure in equalizing reservoir, the displacement of valve core in triple valve and the change of variable vol-ume pneumatic chamber's volume can be compared. The results show that by the application of variable volume pneumatic chamber, the ac-tual situation of pneumatic volume's change of the valve cavity can be correctly reflect, and the model built more scientific. Thus, the model-ing method of applying variable volume pneumatic chamber is feasible.
Intracellular Cadmium Isotope Fractionation
Horner, T. J.; Lee, R. B.; Henderson, G. M.; Rickaby, R. E.
2011-12-01
Recent stable isotope studies into the biological utilization of transition metals (e.g. Cu, Fe, Zn, Cd) suggest several stepwise cellular processes can fractionate isotopes in both culture and nature. However, the determination of fractionation factors is often unsatisfactory, as significant variability can exist - even between different organisms with the same cellular functions. Thus, it has not been possible to adequately understand the source and mechanisms of metal isotopic fractionation. In order to address this problem, we investigated the biological fractionation of Cd isotopes within genetically-modified bacteria (E. coli). There is currently only one known biological use or requirement of Cd, a Cd/Zn carbonic anhydrase (CdCA, from the marine diatom T. weissfloggii), which we introduce into the E. coli genome. We have also developed a cleaning procedure that allows for the treating of bacteria so as to study the isotopic composition of different cellular components. We find that whole cells always exhibit a preference for uptake of the lighter isotopes of Cd. Notably, whole cells appear to have a similar Cd isotopic composition regardless of the expression of CdCA within the E. coli. However, isotopic fractionation can occur within the genetically modified E. coli during Cd use, such that Cd bound in CdCA can display a distinct isotopic composition compared to the cell as a whole. Thus, the externally observed fractionation is independent of the internal uses of Cd, with the largest Cd isotope fractionation occurring during cross-membrane transport. A general implication of these experiments is that trace metal isotopic fractionation most likely reflects metal transport into biological cells (either actively or passively), rather than relating to expression of specific physiological function and genetic expression of different metalloenzymes.
Fraction Reduction through Continued Fractions
Carley, Holly
2011-01-01
This article presents a method of reducing fractions without factoring. The ideas presented may be useful as a project for motivated students in an undergraduate number theory course. The discussion is related to the Euclidean Algorithm and its variations may lead to projects or early examples involving efficiency of an algorithm.
Energy Technology Data Exchange (ETDEWEB)
Kim, Yong Pyo; Kim, Sung Jun; Chung, Tae Sub; Yoo, Yeon Hwa; Yoon, Choon Sik [Dept. of Radiology, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul (Korea, Republic of); Kanneengiesser, Stephan [MR Applications Development, Siemens AG, Healthcare Sector, Erlangen (Germany); Paek, Moon Young [Siemens Ltd., Seoul (Korea, Republic of); Song, Ho Taek; Lee, Young Han; Suh, Jin Suck [Dept. of Radiology, Severance Hospital, Yonsei University College of Medicine, Seoul (Korea, Republic of)
2014-12-15
To assess the feasibility of T2{sup *}-corrected fat-signal fraction (FF) map by using the three-echo volume interpolated breath-hold gradient echo (VIBE) Dixon sequence to differentiate between malignant marrow-replacing lesions and benign red marrow deposition of vertebrae. We assessed 32 lesions from 32 patients who underwent magnetic resonance imaging after being referred for assessment of a known or possible vertebral marrow abnormality. The lesions were divided into 21 malignant marrow-replacing lesions and 11 benign red marrow depositions. Three sequences for the parameter measurements were obtained by using a 1.5-T MR imaging scanner as follows: three-echo VIBE Dixon sequence for FF; conventional T1-weighted imaging for the lesion-disc ratio (LDR); pre- and post-gadolinium enhanced fat-suppressed T1-weighted images for the contrast-enhancement ratio (CER). A region of interest was drawn for each lesion for parameter measurements. The areas under the curve (AUC) of the parameters and their sensitivities and specificities at the most ideal cutoff values from receiver operating characteristic curve analysis were obtained. AUC, sensitivity, and specificity were respectively compared between FF and CER. The AUCs of FF, LDR, and CER were 0.96, 0.80, and 0.72, respectively. In the comparison of diagnostic performance between the FF and CER, the FF showed a significantly larger AUC as compared to the CER (p = 0.030), although the difference of sensitivity (p = 0.157) and specificity (p = 0.157) were not significant. Fat-signal fraction measurement using T2{sup *}-corrected three-echo VIBE Dixon sequence is feasible and has a more accurate diagnostic performance, than the CER, in distinguishing benign red marrow deposition from malignant bone marrow-replacing lesions.
Energy Technology Data Exchange (ETDEWEB)
Regalbuto, M.C.; Misra, B.; Chamberlain, D.B.; Leonard, R.A.; Vandegrift, G.F.
1992-04-01
The Generic TRUEX Model (GTM) was used to design a flowsheet for the TRUEX solvent extraction process that would be used to determine its instrumentation and control requirements. Sensitivity analyses of the key process variables, namely, the aqueous and organic flow rates, feed compositions, and the number of contactor stages, were carried out to assess their impact on the operation of the TRUEX process. Results of these analyses provide a basis for the selection of an instrument and control system and the eventual implementation of a control algorithm. Volume Two of this report is an evaluation of the instruments available for measuring many of the physical parameters. Equations that model the dynamic behavior of the TRUEX process have been generated. These equations can be used to describe the transient or dynamic behavior of the process for a given flowsheet in accordance with the TRUEX model. Further work will be done with the dynamic model to determine how and how quickly the system responds to various perturbations. The use of perturbation analysis early in the design stage will lead to a robust flowsheet, namely, one that will meet all process goals and allow for wide control bounds. The process time delay, that is, the speed with which the system reaches a new steady state, is an important parameter in monitoring and controlling a process. In the future, instrument selection and point-of-variable measurement, now done using the steady-state results reported here, will be reviewed and modified as necessary based on this dynamic method of analysis.
Xiong, Jianyin; Yan, Wei; Zhang, Yinping
2011-12-01
The initial emittable formaldehyde and VOC concentration in building materials (C(0)) is a key parameter for characterizing and classifying these materials. Various methods have been developed to measure this parameter, but these generally require a long test time. In this paper we develop a convenient and rapid method, the variable volume loading (VVL) method, to simultaneously measure C(0) and the material/air partition coefficient (K). This method has the following features: (a) it requires a relatively short experimental time (less than 24 h for the cases studied); and (b) is convenient for routine measurement. Using this method, we determined C(0) and K of formaldehyde, propanal and hexanal in one kind of medium density fiberboard, and repeated experiments were performed to reduce measurement error. In addition, an extended-C-history method is proposed to determine the diffusion coefficient and the convective mass transfer coefficient. The VVL method is validated by comparing model predicted results based on the determined parameters with experimental data. The determined C(0) of formaldehyde obtained via this method is less than 10% of the total concentration using the perforator method recommended by the Chinese National Standard, suggesting that the total concentration may not be appropriate to predict emission characteristics, nor for material classification.
Jensen, Dane A; Macinga, David R; Shumaker, David J; Bellino, Roberto; Arbogast, James W; Schaffner, Donald W
2017-06-01
The literature on hand washing, while extensive, often contains conflicting data, and key variables are only superficially studied or not studied at all. Some hand washing recommendations are made without scientific support, and agreement between recommendations is limited. The influence of key variables such as soap volume, lather time, water temperature, and product formulation on hand washing efficacy was investigated in the present study. Baseline conditions were 1 mL of a bland (nonantimicrobial) soap, a 5-s lather time, and 38°C (100°F) water temperature. A nonpathogenic strain of Escherichia coli (ATCC 11229) was the challenge microorganism. Twenty volunteers (10 men and 10 women) participated in the study, and each test condition had 20 replicates. An antimicrobial soap formulation (1% chloroxylenol) was not significantly more effective than the bland soap for removing E. coli under a variety of test conditions. Overall, the mean reduction was 1.94 log CFU (range, 1.83 to 2.10 log CFU) with the antimicrobial soap and 2.22 log CFU (range, 1.91 to 2.54 log CFU) with the bland soap. Overall, lather time significantly influenced efficacy in one scenario, in which a 0.5-log greater reduction was observed after 20 s with bland soap compared with the baseline wash (P = 0.020). Water temperature as high as 38°C (100°F) and as low as 15°C (60°F) did not have a significant effect on the reduction of bacteria during hand washing; however, the energy usage differed between these temperatures. No significant differences were observed in mean log reductions experienced by men and women (both 2.08 log CFU; P = 0.988). A large part of the variability in the data was associated with the behaviors of the volunteers. Understanding what behaviors and human factors most influence hand washing may help researchers find techniques to optimize the effectiveness of hand washing.
Institute of Scientific and Technical Information of China (English)
贠慧玲; 王军辉; 赵秋玲; 李银梅
2013-01-01
The seasonal dynamics of the leaf area index ( LAI) and the canopy gap fraction of Catalpa bungei were measured by using a LAI - 2000 plant canopy analyzer. The results showed that LAI among different clones had significantly seasonal variability, and the LAI changing trends of different clones were similar and characterized by an inverse "V" curve, with the peak occurring in September. So were the canopy gaps, whereas with an exceptional "V" curve and the valley occurring in September as well. Obviously, the seasonal variability of the LAI and the canopy gap fraction were completely opposite. Additionally, seasonal differences in leaf angels of Catalpa bungei fluctuated within a limited range, representing a flat canopy pattern. However, there was a big change in canopy uniformity. The well-grown clones have the best canopy uniformity, the poor growth clones have the most inhomogeneous. Also, the correlation between LAI and canopy gap fraction was extremely significant, effectively characterized by an exponential equation y = ae-bx, with a determinant coefficient of above 0.980.%应用LAI-2000植物冠层分析仪,测定了楸树叶面积指数(LAI)和冠层空隙度的季节动态.结果表明:29个楸树无性系叶面积指数均呈现出明显的季节性变化,变化总趋势均呈先上升再下降的单峰曲线,峰值出现在9月,无性系间叶面积指数呈极显著的差异；楸树冠层空隙度也呈现明显的季节性,变化总趋势呈现先下降再上升的单峰曲线,最低峰值出现在9月.楸树是喜平型冠层,叶倾角的季节变化不大,均在一定范围内波动.楸树冠层均匀性差异较大,生长较好的无性系冠层均匀性较好,生长较差的无性系冠层均匀性较差.分析发现,楸树叶面积指数和冠层空隙度相关极显著,并且呈指数回归的关系(R2 ＞0.980),回归式为:y=ae-bx.
Energy Technology Data Exchange (ETDEWEB)
Santos, Cesar A.G.; Correa, Jorge E. [Para Univ., Belem (Brazil). Centro Tecnologico. Dept. de Engenharia Mecanica]. E-mails: gsantos@ufpa.br; jecorrea@amazon.com.br
2000-07-01
This work performs a comparative analysis among the constant and variable air volume multi zones acclimation systems, used for provide the thermal comfort in buildings. The work used the simulation HVAC2KIT computer program. The results of sensible and latent heats transfer rates on the cooling and dehumidification, inflating fan capacity, and heat transfer on the final heating condenser were obtained and analysed for the climate conditions of the Brazilian city of Belem from Para State, presenting hot and humid climate during all the year.
Institute of Scientific and Technical Information of China (English)
熊娥; 闫锋; 张文鹏
2013-01-01
Because of inherent characters of rubber materials,there exists some differences on anti-swelling property of rubber materials in gasoline with different methanol volume fraction.Immersion tests in gasoline 93# or gasoline with different methanol proportions are conducted to show the anti-swelling property of 3 rubber materials commonly used in motor vehicles.The results show that silicone rubber has better anti-swelling property in gasoline with high methanol proportion; on the contrary,fluorine rubber has good resistance to swelling in low-proportion-methanol gasoline; Nitrile Rubber has good antiswelling property in all gasoline with different proportion of methanol.%由于橡胶材料自身的特性不同,对甲醇体积分数不同的甲醇汽油的抗膨胀性存在差异,采用汽车上常见的3种橡胶材料分别在93#汽油和不同甲醇体积分数的甲醇汽油中进行浸泡实验.试验结果表明,硅橡胶在高比例甲醇汽油中抗膨胀性较好,氟橡胶在低比例甲醇汽油中抗膨胀性较好,而丁腈类橡胶在不同比例甲醇汽油中均有很好的抗膨胀性.
Directory of Open Access Journals (Sweden)
Chan-Gi Park
2016-01-01
Full Text Available Hybrid glass/jute fiber reinforced polymer (HGJFRP composite bars were manufactured for concrete structures, and their interlaminar shear stress and tensile performance were evaluated. HGJFRP composite bars were manufactured using a combination of pultrusion and braiding processes. Jute fiber was surface-treated with a silane coupling agent. The mixing ratio of the fiber to the vinyl ester used in the HGJFRP composite bars was 7 : 3. Jute fiber was used to replace glass fiber in proportions of 0, 30, 50, 70, and 100%. The interlaminar shear stress decreased as the proportion of jute fiber increased. Fractures appeared due to delamination between the surface-treated component and the main part of the HGJFRP composite bar. Tensile load-strain curves with 50% jute fiber exhibited linear behavior. With a jute fiber volume fraction of 70%, some plastic deformation occurred. A jute fiber mixing ratio of 100% resulted in a display of linear elastic brittle behavior from the fiber; however, when the surface of the fiber was coated with poly(vinyl acetate, following failure, the jute fiber exhibited partial load resistance. The tensile strength decreased as the jute fiber content increased; however, the tensile strength did not vary linearly with jute fiber content.
Energy Technology Data Exchange (ETDEWEB)
Haslam, J J; Wall, M A; Johnson, D L; Mayhall, D J; Schwartz, A J
2005-07-13
We have measured and modeled the change in electrical resistivity due to partial transformation to the martensitic {alpha}{prime}-phase in a {delta}-phase Pu-Ga matrix. The primary objective is to relate the change in resistance, measured with a 4-probe technique during the transformation, to the volume fraction of the {alpha}{prime} phase created in the microstructure. Analysis by finite element methods suggests that considerable differences in the resistivity may be anticipated depending on the orientational and morphological configurations of the {alpha}{prime} particles. Finite element analysis of the computed resistance of an assembly of lenticular shaped particles indicates that series resistor or parallel resistor approximations are inaccurate and can lead to an underestimation of the predicted amount of {alpha}{prime} in the sample by 15% or more. Comparison of the resistivity of a simulated network of partially transformed grains or portions of grains suggests that a correction to the measured resistivity allows quantification of the amount of {alpha}{prime} phase in the microstructure with minimal consideration of how the {alpha}{prime} morphology may evolve. It is found that the average of the series and parallel resistor approximations provide the most accurate relationship between the measured resistivity and the amount of {alpha}{prime} phase. The methods described here are applicable to any evolving two-phase microstructure in which the resistance difference between the two phases is measurable.
Fractional conservation laws in optimal control theory
Frederico, Gastao S F
2007-01-01
Using the recent formulation of Noether's theorem for the problems of the calculus of variations with fractional derivatives, the Lagrange multiplier technique, and the fractional Euler-Lagrange equations, we prove a Noether-like theorem to the more general context of the fractional optimal control. As a corollary, it follows that in the fractional case the autonomous Hamiltonian does not define anymore a conservation law. Instead, it is proved that the fractional conservation law adds to the Hamiltonian a new term which depends on the fractional-order of differentiation, the generalized momentum, and the fractional derivative of the state variable.
van Dongen, Joris A.; Stevens, Hieronymus P.; Parvizi, Mojtaba; van der Lei, Berend; Harmsen, Martin C.
2016-01-01
Autologous adipose tissue transplantation is clinically used to reduce dermal scarring and to restore volume loss. The therapeutic benefit on tissue damage more likely depends on the stromal vascular fraction of adipose tissue than on the adipocyte fraction. This stromal vascular fraction can be obt
van Dongen, Joris A; Stevens, Hieronymus P; Parvizi, Mojtaba; van der Lei, Berend; Harmsen, Martin C
2016-01-01
Autologous adipose tissue transplantation is clinically used to reduce dermal scarring and to restore volume loss. The therapeutic benefit on tissue damage more likely depends on the stromal vascular fraction of adipose tissue than on the adipocyte fraction. This stromal vascular fraction can be obt
van Dongen, Joris A.; Stevens, Hieronymus P.; Parvizi, Mojtaba; van der Lei, Berend; Harmsen, Martin C.
2016-01-01
Autologous adipose tissue transplantation is clinically used to reduce dermal scarring and to restore volume loss. The therapeutic benefit on tissue damage more likely depends on the stromal vascular fraction of adipose tissue than on the adipocyte fraction. This stromal vascular fraction can be obt
Momentum fractionation on superstrata
Bena, Iosif; Martinec, Emil; Turton, David; Warner, Nicholas P.
2016-05-01
Superstrata are bound states in string theory that carry D1, D5, and momentum charges, and whose supergravity descriptions are parameterized by arbitrary functions of (at least) two variables. In the D1-D5 CFT, typical three-charge states reside in high-degree twisted sectors, and their momentum charge is carried by modes that individually have fractional momentum. Understanding this momentum fractionation holographically is crucial for understanding typical black-hole microstates in this system. We use solution-generating techniques to add momentum to a multi-wound supertube and thereby construct the first examples of asymptotically-flat superstrata. The resulting supergravity solutions are horizonless and smooth up to well-understood orbifold singularities. Upon taking the AdS3 decoupling limit, our solutions are dual to CFT states with momentum fractionation. We give a precise proposal for these dual CFT states. Our construction establishes the very nontrivial fact that large classes of CFT states with momentum fractionation can be realized in the bulk as smooth horizonless supergravity solutions.
Directory of Open Access Journals (Sweden)
Anselmo Grego Neto
2009-04-01
Full Text Available A realização de alongamento muscular antes de treinamentos e competições está enraizada na cultura dos profissionais que trabalham com prescrição de exercício. Acredita-se no alongamento como forma de aprimoramento do desempenho e prevenção de lesões. No entanto, muitos estudos têm mostrado que o alongamento pode produzir efeitos deletérios na capacidade de produção de força muscular. Algumas questões relevantes nesse contexto relacionam-se com o volume de alongamento necessário para produzir déficits de força e com os mecanismos fisiológicos responsáveis pelos mesmos. A proposta deste estudo foi investigar as alterações no desempenho isocinético do grupo muscular dos isquiotibiais mediante dois protocolos de alongamento estático com diferentes volumes. Trinta e seis voluntários adultos do sexo masculino foram distribuídos em três grupos: E1, E2 e C. Todos os participantes realizaram um aquecimento sistêmico e depois foram submetidos a avaliações da amplitude de movimento ativa (ADM de flexão do quadril e isocinética. Aos participantes dos grupos E1 e E2 foram aplicados protocolos de alongamento estático com volumes de 180s (4 x 45s e 360s (8 x 45s, respectivamente, e estes foram novamente avaliados. Os participantes do grupo C foram submetidos à segunda avaliação, após permanecer em repouso pelo tempo de 270s. As variáveis avaliadas foram a ADM, o pico de torque (PT, o trabalho máximo (TM e o trabalho total (TT. Observou-se que ambos os protocolos promoveram aumento da ADM, mas as variáveis PT e TM sofreram déficits somente no grupo E2. A variável TT, no entanto, manteve-se inalterada nos grupos E1 e E2. Os resultados sugerem, portanto, que as alterações na rigidez muscular, que causaram ganhos na ADM, não seriam as únicas responsáveis pelos déficits de força. Além disso, conclui-se que a capacidade máxima de produção de força é dependente do volume de alongamento, mas a produção de
Schreurs, L M A; Busz, D M; Paardekooper, G M R M; Beukema, J C; Jager, P L; Van der Jagt, E J; van Dam, G M; Groen, H; Plukker, J Th M; Langendijk, J A
2010-08-01
Target volume definition in modern radiotherapy is based on planning computed tomography (CT). So far, 18-fluorodeoxyglucose positron emission tomography (FDG-PET) has not been included in planning modality in volume definition of esophageal cancer. This study evaluates fusion of FDG-PET and CT in patients with esophageal cancer in terms of geographic misses and inter-observer variability in volume definition. In 28 esophageal cancer patients, gross, clinical and planning tumor volumes (GTV; CTV; PTV) were defined on planning CT by three radiation oncologists. After software-based emission tomography and computed tomography (PET/CT) fusion, tumor delineations were redefined by the same radiation-oncologists. Concordance indexes (CCI's) for CT and PET/CT based GTV, CTV and PTV were calculated for each pair of observers. Incorporation of PET/CT modified tumor delineation in 17/28 subjects (61%) in cranial and/or caudal direction. Mean concordance indexes for CT-based CTV and PTV were 72 (55-86)% and 77 (61-88)%, respectively, vs. 72 (47-99)% and 76 (54-87)% for PET/CT-based CTV and PTV. Paired analyses showed no significant difference in CCI between CT and PET/CT. Combining FDG-PET and CT may improve target volume definition with less geographic misses, but without significant effects on inter-observer variability in esophageal cancer.
Fractional complex transforms for fractional differential equations
National Research Council Canada - National Science Library
Ibrahim, Rabha W
2012-01-01
The fractional complex transform is employed to convert fractional differential equations analytically in the sense of the Srivastava-Owa fractional operator and its generalization in the unit disk...
Institute of Scientific and Technical Information of China (English)
张建云; 张灿铭; 李普同; 崔霞
2014-01-01
对高体积分数 SiCp/Al 复合材料进行前处理,再化学镀镍。研究了除油、粗化、活化对 SiCp/Al复合材料化学镀镍的影响。分析了镀镍层的显微组织。结果表明,有机溶剂除油比碱液除油效果好。H2 O2系粗化比 HF 系粗化更为适宜。在由醋酸镍、次亚磷酸钠和乙醇组成的活化剂中室温浸润,然后160℃温度下热还原30 min,化学镀镍镀速较高。前处理后在 SiCp/Al 复合材料表面化学镀镍可沉积上致密、均匀、结合良好的镀镍层。%The high volume fraction SiCp/Al composite was processed by pretreatment,then it was proceeded by electroless nickel plating.The influence of deoiling,roughening,activating on electroless nickel plating on SiCp/Al composite was investigated.The microstructure of electroless nickel plating on composite was ana-lyzed.The results show that organic solvent was better than alkaline solvent for deoiling.H2 O2 system was more appropriate than HF system for roughening.Infiltrating in activation solution consisted nickel acetate,so-dium hypophosphite and alcohol at room temperature,then thermo deoxidizing at 160 ℃ temperature for 30 min,the procedure makes electroless nickel plating rate higher.After pretreatment,electroless nickel plating deposited on SiCp/Al composite surface was dense,uniform,firmly combined.
Fractional complex transform for fractional differential equations
National Research Council Canada - National Science Library
Lİ, Zheng Biao; HE, Ji Huan
2010-01-01
Fractional complex transform is proposed to convert fractional differential equations into ordinary differential equations, so that all analytical methods devoted to advanced calculus can be easily...
Bergstra, Jan A.
2015-01-01
In the context of an involutive meadow a precise definition of fractions is formulated and on that basis formal definitions of various classes of fractions are given. The definitions follow the fractions as terms paradigm. That paradigm is compared with two competing paradigms for storytelling on fractions: fractions as values and fractions as pairs.
Momentum Fractionation on Superstrata
Bena, Iosif; Turton, David; Warner, Nicholas P
2016-01-01
Superstrata are bound states in string theory that carry D1, D5, and momentum charges, and whose supergravity descriptions are parameterized by arbitrary functions of (at least) two variables. In the D1-D5 CFT, typical three-charge states reside in high-degree twisted sectors, and their momentum charge is carried by modes that individually have fractional momentum. Understanding this momentum fractionation holographically is crucial for understanding typical black-hole microstates in this system. We use solution-generating techniques to add momentum to a multi-wound supertube and thereby construct the first examples of asymptotically-flat superstrata. The resulting supergravity solutions are horizonless and smooth up to well-understood orbifold singularities. Upon taking the AdS3 decoupling limit, our solutions are dual to CFT states with momentum fractionation. We give a precise proposal for these dual CFT states. Our construction establishes the very nontrivial fact that large classes of CFT states with mom...
Energy Technology Data Exchange (ETDEWEB)
Garcia-Barriocanal, J.; Garces, G.; Perez, P.; Adeva, P.
2005-07-01
The mechanical properties of Ni{sub 3}Al-Cr reinforced with 10% in volume fraction of chromium particles produced by powder metallurgy have been studied. For this purpose, milled powders with composition of Ni-20.9Al-8Cr-0.49B (% st.) with and without the addition of 10% in volume fraction of chromium particles have been produced. Both alloys were consolidated by hot isostatic pressing (HIP). After HIP, heat treatment was applied to homogenize the microstructure. The chromium reinforcement has an important effect in the yield strength and ultimate strength increase. The reinforced alloy presents a yield strength of 1300 MPa at room temperature with respect to 800 MPa for the un-reinforced material. After heat treatment, the yield strength of both alloys does not change significantly. However, a decrease in ductility and ultimate tensile strength have been observed. (Author) 4 refs.
Directory of Open Access Journals (Sweden)
Kawel Nadine
2012-04-01
Full Text Available Abstract Purpose Myocardial T1 relaxation time (T1 time and extracellular volume fraction (ECV are altered in patients with diffuse myocardial fibrosis. The purpose of this study was to perform an intra-individual assessment of normal T1 time and ECV for two different contrast agents. Methods A modified Look-Locker Inversion Recovery (MOLLI sequence was acquired at 3 T in 24 healthy subjects (8 men; 28 ± 6 years at mid-ventricular short axis pre-contrast and every 5 min between 5-45 min after injection of a bolus of 0.15 mmol/kg gadopentetate dimeglumine (Gd-DTPA; Magnevist® (exam 1 and 0.1 mmol/kg gadobenate dimeglumine (Gd-BOPTA; Multihance® (exam 2 during two separate scanning sessions. T1 times were measured in myocardium and blood on generated T1 maps. ECVs were calculated as ΔR1myocardium/ΔR1blood*1−hematocrit. Results Mean pre-contrast T1 relaxation times for myocardium and blood were similar for both the first and second CMR exam (p > 0.5. Overall mean post-contrast myocardial T1 time was 15 ± 2 ms (2.5 ± 0.7% shorter for Gd-DTPA at 0.15 mmol/kg compared to Gd-BOPTA at 0.1 mmol/kg (p 0.05. Between 5 and 45 minutes after contrast injection, mean ECV values increased linearly with time for both contrast agents from 0.27 ± 0.03 to 0.30 ± 0.03 (p pre-contrast myocardial T1 relaxation time (CV 4.5% [exam 1] and 3.0% [exam 2], respectively. ECV with Gd-DTPA was highly correlated to ECV by Gd-BOPTA (r = 0.803; p Conclusion In comparison to pre-contrast myocardial T1 relaxation time, variation in ECV values of normal subjects is larger. However, absolute differences in ECV between Gd-DTPA and Gd-BOPTA were small and rank correlation was high. There is a small and linear increase in ECV over time, therefore ideally images should be acquired at the same delay after contrast injection.
Fisher, Stephen D
1999-01-01
The most important topics in the theory and application of complex variables receive a thorough, coherent treatment in this introductory text. Intended for undergraduates or graduate students in science, mathematics, and engineering, this volume features hundreds of solved examples, exercises, and applications designed to foster a complete understanding of complex variables as well as an appreciation of their mathematical beauty and elegance. Prerequisites are minimal; a three-semester course in calculus will suffice to prepare students for discussions of these topics: the complex plane, basic
Institute of Scientific and Technical Information of China (English)
ZHU Yaohua; WEI Zexun; WANG Yonggang; GUAN Yuping; WANG Xinyi
2014-01-01
The annual mean volume and heat transport sketches through the inter-basin passages and transoceanic sections have been constructed based on 1 400-year spin up results of the MOM4p1. The spin up starts from a state of rest, driven by the monthly climatological mean force from the NOAA World Ocean Atlas (1994). The volume transport sketch reveals the northward transport throughout the Pacific and southward trans-port at all latitudes in the Atlantic. The annual mean strength of the Pacific-Arctic-Atlantic through flow is 0.63×106 m3/s in the Bering Strait. The majority of the northward volume transport in the southern Pacific turns into the Indonesian through flow (ITF) and joins the Indian Ocean equatorial current, which subse-quently flows out southward from the Mozambique Channel, with its majority superimposed on the Ant-arctic Circumpolar Current (ACC). This anti-cyclonic circulation around Australia has a strength of 11×106 m3/s according to the model-produced result. The atmospheric fresh water transport, known as P-E+R (pre-cipitation minus evaporation plus runoff ), constructs a complement to the horizontal volume transport of the ocean. The annual mean heat transport sketch exhibits a northward heat transport in the Atlantic and poleward heat transport in the global ocean. The surface heat flux acts as a complement to the horizontal heat transport of the ocean. The climatological volume transports describe the most important features through the inter-basin passages and in the associated basins, including:the positive P-E+R in the Arctic substantially strengthening the East Greenland Current in summer;semiannual variability of the volume transport in the Drake Passage and the southern Atlantic-Indian Ocean passage;and annual transport vari-ability of the ITF intensifying in the boreal summer. The climatological heat transports show heat storage in July and heat deficit in January in the Arctic;heat storage in January and heat deficit in July in the
Predicting equilibrium uranium isotope fractionation in crystals and solution
Schauble, E. A.
2015-12-01
Despite the rapidly growing interest in using 238U/235U measurements as a proxy for changes in oxygen abundance in surface and near-surface environments, the present theoretical understanding of uranium isotope fractionation is limited to a few simple gas-phase molecules and analogues of dissolved species (e.g., 1,2,3). Understanding uranium isotope fractionation behavior in more complicated species, such as crystals and adsorption complexes, will help in the design and interpretation of experiments and field studies, and may suggest other uses for 38U/235U measurements. In this study, a recently developed first-principles method for estimating the nuclear volume component of field shift fractionation in crystals and complex molecular species (4) is combined with mass-dependent fractionation theory to predict equilibrium 38U/235U fractionations in aqueous and crystalline uranium compounds, including uraninite (UO2). The nuclear field shift effect, caused by the interaction of electrons with the finite volume of the positive charge distribution in uranium nuclei, is estimated using Density Functional Theory and the Projector Augmented Wave method (DFT-PAW). Tests against relativistic electronic structure calculations and Mössbauer isomer shift data indicate that the DFT-PAW method is reasonably accurate, while being much better suited to models of complex and crystalline species. Initial results confirm previous predictions that the nuclear volume effect overwhelms mass depdendent fractionation in U(VI)-U(IV) exchange reactions, leading to higher 238U/235U in U(IV) species (i.e., for UO2 xtal vs. UO22+aq, ln αNV ≈ +1.8‰ , ln αMD ≈ -0.8‰, ln αTotal ≈ +1.0‰ at 25ºC). UO2 and U(H2O)94+, are within ~0.4‰ of each other, while U(VI) species appear to be more variable. This suggests that speciation is likely to significantly affect natural uranium isotope fractionations, in addition to oxidation state. Tentatively, it appears that uranyl-type (UO22
Tenreiro Machado, J. A.
2015-08-01
This paper addresses the matrix representation of dynamical systems in the perspective of fractional calculus. Fractional elements and fractional systems are interpreted under the light of the classical Cole-Cole, Davidson-Cole, and Havriliak-Negami heuristic models. Numerical simulations for an electrical circuit enlighten the results for matrix based models and high fractional orders. The conclusions clarify the distinction between fractional elements and fractional systems.
Directory of Open Access Journals (Sweden)
Takashi Hanada
2014-01-01
Full Text Available We estimated variations in rectal volumes and dosimetry values including NTCP with interfractional motion during prostate IG-IMRT. Rectal volumes, DVH parameters, and NTCPs of 20 patients were analyzed. For this patient population, the median (range volume on the initial plan for the rectum was 45.6 cc (31.3–82.0, showing on-treatment spread around the initial prediction based on the initial plan. DVH parameters of on-treatment CBCT analyses showed systematic regularity shift from the prediction based on the initial plan. Using the Lyman-Kutcher-Burman model, NTCPs of predicted late rectal bleeding toxicity of rectal grade ≥ 2 (RTOG and the QUANTEC update rectal toxicity for the prediction based on the initial plan were 0.09% (0.02–0.24 and 0.02% (0.00–0.07, respectively, with NTCPs from on-treatment CBCT analyses being 0.35% (0.01–6.16 and 0.12% (0.00–4.11, respectively. Using the relative seriality model, for grade ≥ 2 bleeding rectal toxicity, NTCP of the prediction based on the initial plan was 0.64% (0.15–1.22 versus 1.48% (0.18–7.66 for on-treatment CBCT analysis. Interfraction variations in rectal volumes occur in all patients due to physiological changes. Thus, rectal assessment during 2D-based IG-IMRT using NTCP models has the potential to provide useful and practical dosimetric verification.
Directory of Open Access Journals (Sweden)
C. I. Lehmann
2012-07-01
Full Text Available Convective gravity wave (GW sources are spatially localized and emit at the same time waves with a wide spectrum of phase speeds. Any wave analysis therefore compromises between spectral and spatial resolution. Future satellite borne limb imagers will for a first time provide real 3-D volumes of observations. These volumes will be however limited which will impose further constraints on the analysis technique. In this study a three dimensional few-wave approach fitting sinusoidal waves to limited 3-D volumes is introduced. The method is applied to simulated GWs above typhoon Ewiniar and GW momentum flux is estimated from temperature fluctuations. Phase speed spectra as well as average profiles of positive, negative and net momentum fluxes are compared to momentum flux estimated by Fourier transform as well as spatial averaging of wind fluctuations. The results agree within 10–20%. The few-wave method can also reveal the spatial orientation of the GWs with respect to the source. The relevance of the results for different types of measurements as well as its applicability to model data is discussed.
Eninger, M.U.
The primary objective of this study was to provide a description of the process variables of trade and industrial education, such as curriculum, facilities, guidance and placement services, teachers and instructional methods, advisory committees and community relations, and administration. Data were collected from a stratified random sample of 100…
Initialized Fractional Calculus
Lorenzo, Carl F.; Hartley, Tom T.
2000-01-01
This paper demonstrates the need for a nonconstant initialization for the fractional calculus and establishes a basic definition set for the initialized fractional differintegral. This definition set allows the formalization of an initialized fractional calculus. Two basis calculi are considered; the Riemann-Liouville and the Grunwald fractional calculi. Two forms of initialization, terminal and side are developed.
Institute of Scientific and Technical Information of China (English)
唐青龙; 张鹏; 刘海峰; 尧命发
2015-01-01
激光诱导炽光(LII)法是一种用于测量火焰中碳烟体积分数的光学测试方法.本文介绍了LII的基本原理以及LII实现定量测量的常见标定方法,建立了一套基于双色法-激光诱导炽光法(2C-LII)的用于柴油机缸内燃烧过程碳烟体积分数定量测量的测试系统,该测试系统采用双成像原理,可以实现多点标定和全视场范围内的碳烟体积分数测量.在一台工作在1200 r∙min-1、喷油量21 mg的光学单缸柴油机上,研究了60、100和140 MPa三个不同喷油压力下,缸内燃烧过程碳烟的分布情况,结果表明,碳烟自发光出现在燃烧放热率峰值之后,且随着喷油压力提高,碳烟发光持续期缩短,碳烟发光强度降低.测试区域内火焰中的碳烟体积分数范围约为0-50×10-6.不同喷油压力下,碳烟生成初期、碳烟峰值和碳烟氧化三个阶段内平均碳烟体积分数的范围分别是：5×10-6-9×10-6,15×10-6-20×10-6和14×10-6-16×10-6.喷油压力提高后火焰中的碳烟分布区域面积增大,平均碳烟体积分数减小,碳烟体积分数的空间分布趋于均匀.%Laser-induced incandescence (LII) is an optical diagnostic method used to measure the soot volume fraction in a flame. In this paper, the principle of LII and the calibration methods normal y used are introduced. Based on two-color LII theory, a quantitative test system for determining the in-cylinder soot volume fraction was established. A dual imaging setup was used, which can achieve multipoint calibration and ful field-of-view quantification of soot in a diesel engine chamber. An investigation was carried out on an optical diesel engine with the conditions 1200 r∙min-1 and 21 mg fuel injection per cycle, with various injection pressures (60, 100, and 140 MPa). The results show that the natural soot incandescence emerged after the peak rate of combustion heat release. With increasing injection pressure, the duration of natural soot
Houtmeyers, Anneleen; Duchateau, Luc; Grünewald, Bettina; Hermans, Katleen
2016-12-01
Rats (Rattus norvegicus) are increasingly kept as pets, thus more and more requiring veterinary care. Important differences exist between pet and laboratory rats, but little information is available on pet rats. Diagnosis and treatment of pet rat diseases would benefit from RIs specific for this animal population. The aim was to establish RIs for biochemical blood variables, PCV, and body temperature in pet rats. Additionally, influences of sex and feed rationing method (ad libitum, restricted) on these variables were determined. American Society for Veterinary Clinical Pathology (ASVCP) recommendations were followed. Biochemical variables were measured using an automated chemistry analyzer, the VetScan VS2. Nonparametric statistical methods were used to determine RIs and effects of sex and feed rationing method. Reference intervals were established using values of 123 clinically healthy pet rats (except for globulins and albumin/globulin ratio, n = 120) and were: glucose 6.6-13.7 mmol/L, total proteins 66-88 g/L, albumin ≥ 38 g/L, globulins 12-35 g/L, albumin/globulin ratio 1.0-4.7, urea nitrogen 2.5-6.6 mmol/L, creatinine ≤ 53 μmol/L, total bilirubin 4-7 μmol/L, ALP 40-442 IU/L, ALT 22-137 IU/L, amylase 502-1113 IU/L, sodium 133-144 mmol/L, potassium 3.6-5.3 mmol/L, calcium 9.5-10.9 mg/dL, phosphorus 2.3-7.0 mg/dL, PCV 40-50%, and body temperature 35.8-39.3°C. Sex significantly affected 10 variables. No significant influence was found with feed limitation CONCLUSIONS: Reference intervals reported in this study will be useful for interpretation of biochemistry analysis in pet rats and therefore improve pet rat medicine. © 2016 American Society for Veterinary Clinical Pathology.
Easy characterization of petroleum fractions: Part 1
Energy Technology Data Exchange (ETDEWEB)
Miquel, J. (Univ. Politecnica de Catalunya (Spain)); Castells, F. (Univ. Rovira i Virgili, Catalunya (Spain))
1993-12-01
A new method for characterizing petroleum fractions, based on pseudocomponent breakdown using the integral method has been developed. It requires only that one has an atmospheric true boiling point (tbp) distillation curve and known the entire fraction density. The proposed characterization procedure is valid for representing any oil fraction (light or heavy) with a boiling point range smaller than 300 K. It is based on the hypothesis of constant Watson's characterization factor, K[sub w], for all the pseudocomponents. Outside this range, it is less accurate (greater errors in material and molar balances). Therefore, a method considering the variable K[sub w] is best to treat these fractions.
Fraction Sense: Foundational Understandings.
Fennell, Francis Skip; Karp, Karen
2016-08-09
The intent of this commentary is to identify elements of fraction sense and note how the research studies provided in this special issue, in related but somewhat different ways, validate the importance of such understandings. Proficiency with fractions serves as a prerequisite for student success in higher level mathematics, as well as serving as a gateway to many occupations and varied contexts beyond the mathematics classroom. Fraction sense is developed through instructional opportunities involving fraction equivalence and magnitude, comparing and ordering fractions, using fraction benchmarks, and computational estimation. Such foundations are then extended to operations involving fractions and decimals and applications involving proportional reasoning. These components of fraction sense are all addressed in the studies provided in this issue, with particular consideration devoted to the significant importance of the use of the number line as a central representational tool for conceptually understanding fraction magnitude.
Performance of Variable Negative Stiffness MRE Vibration Isolation System
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Run-pu Li
2015-01-01
Full Text Available Magnetorheological elastomer (MRE vibration isolation devices can improve a system’s vibration response via adjustable stiffness and damping under different magnetic fields. Combined with negative stiffness design, these MRE devices can reduce a system’s stiffness and improve the vibration control effect significantly. This paper develops a variable negative stiffness MRE isolation device by combining an improved separable iron core with laminated MREs. The relationship between the negative stiffness and the performance of the device is obtained by mathematical transformation. Its vibration response under simple harmonic excitation at small amplitude and the impact of the volume fraction of soft magnetic particles on the isolation system are also analyzed. The results show that the negative stiffness produced by the magnetic force is a major factor affecting the capacity of the isolation system. Compared to devices of the same size, the isolation system equipped with low-particle volume fraction MREs demonstrates better performance.
Applications of fractional calculus in physics
2000-01-01
Fractional calculus is a collection of relatively little-known mathematical results concerning generalizations of differentiation and integration to noninteger orders. While these results have been accumulated over centuries in various branches of mathematics, they have until recently found little appreciation or application in physics and other mathematically oriented sciences. This situation is beginning to change, and there are now a growing number of research areas in physics which employ fractional calculus.This volume provides an introduction to fractional calculus for physicists, and co
Dewi, D. A. K.; Suryadi, D.; Suratno, T.; Mulyana, E.; Kurniawan, H.
2017-02-01
Introducing fractions is identical to divide an object. Suppose we divide the apple into two parts. One divided into two parts, the question arises whether one part can be called a half or not. Based on this activity, how can students give meaning to fractions. This study aims at designing a different fractions lesson by applying Didactical Design Research. In doing so, we undertook several research phases: 1) thinking what is fractions and why students should learn this concept; 2) designing didactical situation based on identified learning obstacles; and 3) reflecting retrospectively on the lesson design and its implementation as to redesign the fractions lesson. Our analysis revealed that most students held epistemological obstacles in giving meaning of fractions because they only know fractions as numbers that have numerator and denominator. By positioning ourselves as students, we discuss the ideal design to help students in constructing the meaning of fractions.
Edelman, Mark
2014-01-01
In this paper the author presents the results of the preliminary investigation of fractional dynamical systems based on the results of numerical simulations of fractional maps. Fractional maps are equivalent to fractional differential equations describing systems experiencing periodic kicks. Their properties depend on the value of two parameters: the non-linearity parameter, which arises from the corresponding regular dynamical systems; and the memory parameter which is the order of the fractional derivative in the corresponding non-linear fractional differential equations. The examples of the fractional Standard and Logistic maps demonstrate that phase space of non-linear fractional dynamical systems may contain periodic sinks, attracting slow diverging trajectories, attracting accelerator mode trajectories, chaotic attractors, and cascade of bifurcations type trajectories whose properties are different from properties of attractors in regular dynamical systems. The author argues that discovered properties s...
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Edmundo Arteaga
2009-03-01
ó, con éxito, biopsia endomiocárdica del ventrículo derecho en 21 pacientes sintomáticos con CMH. La fracción de volumen de colágeno (FVC miocárdico se determinó por medio de histología. Se determinó la FVC también en fragmentos de nueve corazones normales de individuos fallecidos por causas no cardiacas. Respecto a la FVC, se dividieron a los pacientes en grupos supra e inframedianos (FVC elevada y FVC baja, respectivamente, y se compararon las características clínicas y ecocardiográficas y las curvas de sobrevida. RESULTADOS: Entre los pacientes, la FVC tuvo variación del 1,86% al 29,9%, con mediana en el 6,19%. Ya en los corazones normales, del 0,13% al 1,46%, mediana en el 0,36% (p6,19%, sin que se observara diferencias basales. Sin embargo, tras un período de seguimiento promedio de 110 meses, cuatro muertes ocurrieron (dos súbitas, y otras dos por insuficiencia cardiaca en el grupo con FVC mayor, mientras que los pacientes del grupo con FVC menor estaban vivos al final del período (p=0,02. CONCLUSIÓN: Por primera vez, se asoció prospectivamente la fibrosis miocárdica a un peor diagnóstico en pacientes con CMH. Se deben encaminar esfuerzos hacia la cuantificación de la fibrosis en la CMH, al aceptar que la asociación con el pronóstico puede auxiliar tanto en la estratificación de riesgo para implante de desfibrilador, como en la prescripción de fármacos potencialmente reparadores miocárdicos.BACKGROUND: In hypertrophic cardiomyopathy (HCM, interstitial myocardial fibrosis is an important histological modification that has been associated with sudden death and evolution toward myocardial dilation. OBJECTIVE:To prospectively evaluate the prognostic value of the collagen volume fraction in HCM. METHODS: An endomyocardial biopsy of the right ventricle was successfully performed in 21 symptomatic patients with HCM. The myocardial collagen volume fraction (CVF was determined by histology. The CVF was also determined in fragments of nine normal
DePace, N L; Iskandrian, A S; Hakki, A H; Kane, S A; Segal, B L
1983-04-01
To determine the relation between left ventricular performance during exercise and the extent of coronary artery disease, the results of exercise radionuclide ventriculography were analyzed in 65 patients who also underwent cardiac catheterization. A scoring system was used to quantitate the extent of coronary artery disease. This system takes into account the number and site of stenoses of the major coronary vessels and their secondary branches. The conventional method of interpreting the coronary angiograms indicated that 26 patients had significant coronary artery disease (defined as 70% or more narrowing of luminal diameter) of one vessel, 21 had multivessel disease and 18 had no significant coronary artery disease. Although the exercise left ventricular ejection fraction was significantly higher in patients with no coronary artery disease than in patients with one or multivessel disease (probability [p] less than 0.001), there was considerable overlap among the three groups. With the scoring system, a good correlation was found between the coronary artery disease score and the exercise left ventricular ejection fraction (r = -0.70; p less than 0.001). If the exercise heart rate was 130 beats/min or greater or the age of the patient was 50 years or less, an even better correlation was found (r = -0.73 and r = -0.82, respectively). The exercise ejection fraction (but not the change in ejection fraction, end-diastolic volume and end-systolic volume from rest to exercise) correlated with the extent of coronary artery disease. The exercise ejection fraction is the most important exercise variable that correlates with the extent of coronary artery disease when the latter is assessed quantitatively by a scoring system rather than the conventional method of reporting coronary angiograms. Young age and greater exercise heart rate strengthened the correlation. The change in ejection fraction from rest to exercise is useful in the diagnosis of coronary artery disease
On continued fraction algorithms
Smeets, Ionica
2010-01-01
Is there a good continued fraction approximation between every two bad ones? What is the entropy of the natural extension for alpha-Rosen fractions? How do you find multi-dimensional continued fractions with a guaranteed quality in polynomial time? These, and many more, questions are answered in thi
Graham, Alan; Graham, Louise
2003-01-01
Describes a very successful attempt to teach fractions to year 5 pupils based on pupils making their own fraction pack. Children decided for themselves how to make the fractional slices used in the activity using colored cardboard sheets and templates of a paper circle consisting of 24 equal slices. (Author/NB)
On continued fraction algorithms
Smeets, Ionica
2010-01-01
Is there a good continued fraction approximation between every two bad ones? What is the entropy of the natural extension for alpha-Rosen fractions? How do you find multi-dimensional continued fractions with a guaranteed quality in polynomial time? These, and many more, questions are answered in thi
Institute of Scientific and Technical Information of China (English)
修子扬; 陈国钦; 武高辉; 杨文澍; 刘艳梅
2011-01-01
采用压力浸渗法制备Si3N4体积分数分别为45％、50％和55％的颗粒增强铝基复合材料(Si3N4/Al).研究Si3N4体积分数和T6热处理对Si3N4/Al复合材料微观组织和力学性能的影响.结果表明:Si3N4颗粒分散均匀,Si3N4/Al复合材料浸渗良好,没有明显的孔洞和铸造缺陷；在Si3N4颗粒附近的铝基体中,可以观察到高密度位错；Si3N4/Al复合材料的弯曲强度随着Si3N4体积分数的增大而降低；T6热处理能提高复合材料的强度；复合材料的弹性模量随着Si3N4体积分数的增加而线性增加；在低Si3N4体积分数时,可以观察到更多的撕裂棱和韧窝；T6热处理对断口形貌的影响较小.%Si3N4 particles reinforced aluminium matrix composites (Si3N4/Al) with different particle volume fractions (45％,50％,and 55％) were fabricated by pressure infiltration method.The effects of Si3N4 volume fraction and T6 treatment on mierostructure and mechanical properties of Si3N4/Al composite were investigated.The results show that Si3N4/Al composites are well infiltrated with good particles dispersion and no apparent porosity or significant casting defects are observed.High density of dislocations in Al matrix around Si3N4 particles is observed.The bending strength of Si3N4/Al composites decreases with an increase in Si3N4 volume fraction,and can be greatly improved by T6 treatment.Elastic modulus of composites increases linearly with Si3N4 volume fraction.At a lower Si3N4 volume fraction,more tearing ridge and dimples with elongation are observed.T6 heat treatment shows minor effect on the fracture surface of composite.
Institute of Scientific and Technical Information of China (English)
张洋; 苏洁
2012-01-01
Bering Strait is the only channel connecting the Pacific Ocean and the Arctic Ocean. The Pacific water through the strait is mainly driven by the meridional sea level slop and its inter-annual variation has great influence on the Arctic Ocean. In this study SODA data is applied to the calculation of the monthly mean volume transport through Bering Strait. The factors related to the inter-annual variability of summer volume transport are discussed. The results show that the SSH in the Laptev Sea, the East Siberian Sea, the Chukchi Sea, south of the Beaufort Sea is negatively correlated to the volume transport of Bering Strait in inter-annual scale while the situation is opposite in the eastern shelf of Bering Sea. After analyzing the correlation of the volume flux with the Ekman transport, pumping rate, upper layer salinity, temperature and density, the paper find that the Ekman transport anomaly should be responsible for the relationship between the sea surface height and the volume flux of Bering Strait. When the SLP is positive anomaly o-ver central part of the Arctic Ocean and negative anomaly over Bering Sea basin, the volume transport through Bering Strait will be enlarged. Such SLP anomaly would explain the relationship between the Bering Strait volume transport and the Ekman transport, pumping rate and upper layer water properties to some extend. The paper reveals that the summer SLP's inter-annual variation can change SSH via Ekman transport and finally dominant the volume transport through Bering Strait.%白令海峡是连接太平洋和北冰洋的唯一通道,穿过海峡的海水体积通量在年际尺度上的变化主要取决于海峡南北两侧的海面高度差,白令海峡的入流对北冰洋海洋过程有重要的意义.利用SODA资料计算夏季白令海峡海水体积通量,对其年际变化及成因进行分析.结果表明夏季白令海峡的体积通量主要是正压地转的；当体积通量为正距平时,楚科奇海、东西
The End Noise Control of Variable Air Volume Air-Conditioning System%变风量空调系统末端噪声控制
Institute of Scientific and Technical Information of China (English)
曹勤
2012-01-01
The variable air volume（VAV） air conditioning system with its huge energy advantage more and more widely used.But interior excessive noise problems make installation and debugging personnel feel awkward.In this paper,according to the actual VAV air conditioning system problems in some high-grade building appeared in the construction process,analyzing the end noise source of VAV air conditioning system,making use of the noise attenuation of each part of end unit and noise control at the end is resaerched,and the measures of end noise control are put forward in VAV air conditioning system.%变风量空调系统以其巨大的节能优势越来越得到广泛应用,但是室内噪声超标的问题令安装、调试人员感到棘手。根据实际参加某高档楼盘变风量空调系统建设过程中出现的问题,通过分析变风量空调系统末端噪声的来源,研究利用末端单元各部分噪声的衰减影响来控制末端噪声,提出了变风量空调系统未端噪声的具体控制措施。
Fractional Differential Equations
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Jianping Zhao
2012-01-01
Full Text Available An extended fractional subequation method is proposed for solving fractional differential equations by introducing a new general ansätz and Bäcklund transformation of the fractional Riccati equation with known solutions. Being concise and straightforward, this method is applied to the space-time fractional coupled Burgers’ equations and coupled MKdV equations. As a result, many exact solutions are obtained. It is shown that the considered method provides a very effective, convenient, and powerful mathematical tool for solving fractional differential equations.
Shamim, Atif
2011-03-01
For the first time, a generalized Smith chart is introduced here to represent fractional order circuit elements. It is shown that the standard Smith chart is a special case of the generalized fractional order Smith chart. With illustrations drawn for both the conventional integer based lumped elements and the fractional elements, a graphical technique supported by the analytical method is presented to plot impedances on the fractional Smith chart. The concept is then applied towards impedance matching networks, where the fractional approach proves to be much more versatile and results in a single element matching network for a complex load as compared to the two elements in the conventional approach. © 2010 IEEE.
Institute of Scientific and Technical Information of China (English)
陈清; 沈鹏飞
2015-01-01
单螺杆制冷压缩机的欠压缩和过压缩损失将降低其在不同工况下的能效比。根据压缩机运行工况调节其内容积比，得到合适的压缩终止压力，可减少甚至避免欠压缩或过压缩损失。将可变内容积比技术应用于变频单螺杆压缩机，可提高压缩机在不同工况下的满负荷性能系数，同时还可以提高其综合部分负荷能效比(IPLV)。%The over-compression and under-compression loss during the compression process of the single screw compressor will reduce its coefficient of performance (COP) at different operation conditions. Based on the operation conditions to regulate the built-in volume ratio of the compressor, the suitable pressure at the end of the compression process was obtained, which decreases or avoids the over-compression or under-compression loss. Applying the variable volume ratio technology into the invertor single screw compressor, the full load COP at different operation conditions could be improved, and the integrative part load value (IPLV) of the compressor could also be increased.
Fractional Dynamics and Control
Machado, José; Luo, Albert
2012-01-01
Fractional Dynamics and Control provides a comprehensive overview of recent advances in the areas of nonlinear dynamics, vibration and control with analytical, numerical, and experimental results. This book provides an overview of recent discoveries in fractional control, delves into fractional variational principles and differential equations, and applies advanced techniques in fractional calculus to solving complicated mathematical and physical problems.Finally, this book also discusses the role that fractional order modeling can play in complex systems for engineering and science. Discusses how fractional dynamics and control can be used to solve nonlinear science and complexity issues Shows how fractional differential equations and models can be used to solve turbulence and wave equations in mechanics and gravity theories and Schrodinger’s equation Presents factional relaxation modeling of dielectric materials and wave equations for dielectrics Develops new methods for control and synchronization of...
Dey, Aloke
2009-01-01
A one-stop reference to fractional factorials and related orthogonal arrays.Presenting one of the most dynamic areas of statistical research, this book offers a systematic, rigorous, and up-to-date treatment of fractional factorial designs and related combinatorial mathematics. Leading statisticians Aloke Dey and Rahul Mukerjee consolidate vast amounts of material from the professional literature--expertly weaving fractional replication, orthogonal arrays, and optimality aspects. They develop the basic theory of fractional factorials using the calculus of factorial arrangements, thereby providing a unified approach to the study of fractional factorial plans. An indispensable guide for statisticians in research and industry as well as for graduate students, Fractional Factorial Plans features: * Construction procedures of symmetric and asymmetric orthogonal arrays. * Many up-to-date research results on nonexistence. * A chapter on optimal fractional factorials not based on orthogonal arrays. * Trend-free plans...
Maiti, Moumita; Vinutha, H. A.; Sastry, Srikanth; Heussinger, Claus
2015-10-01
Using an athermal quasistatic simulation protocol, we study the distribution of free volumes in sheared hard-particle packings close to, but below, the random-close packing threshold. We show that under shear, and independent of volume fraction, the free volumes develop features similar to close-packed systems — particles self-organize in a manner as to mimick the isotropically jammed state. We compare athermally sheared packings with thermalized packings and show that thermalization leads to an erasure of these structural features. The temporal evolution in particular the opening-up and the closing of free-volume patches is associated with the single-particle dynamics, showing a crossover from ballistic to diffusive behavior.
The radiosurgery fractionation quandary: single fraction or hypofractionation?
Kirkpatrick, John P; Soltys, Scott G; Lo, Simon S; Beal, Kathryn; Shrieve, Dennis C; Brown, Paul D
2017-04-01
Stereotactic radiosurgery (SRS), typically administered in a single session, is widely employed to safely, efficiently, and effectively treat small intracranial lesions. However, for large lesions or those in close proximity to critical structures, it can be difficult to obtain an acceptable balance of tumor control while avoiding damage to normal tissue when single-fraction SRS is utilized. Treating a lesion in 2 to 5 fractions of SRS (termed "hypofractionated SRS" [HF-SRS]) potentially provides the ability to treat a lesion with a total dose of radiation that provides both adequate tumor control and acceptable toxicity. Indeed, studies of HF-SRS in large brain metastases, vestibular schwannomas, meningiomas, and gliomas suggest that a superior balance of tumor control and toxicity is observed compared with single-fraction SRS. Nonetheless, a great deal of effort remains to understand radiobiologic mechanisms for HF-SRS driving the dose-volume response relationship for tumors and normal tissues and to utilize this fundamental knowledge and the results of clinic studies to optimize HF-SRS. In particular, the application of HF-SRS in the setting of immunomodulatory cancer therapies offers special challenges and opportunities.
Packing Effect of Excluded Volume on Hard-Sphere Colloids
Institute of Scientific and Technical Information of China (English)
肖长明; 金国钧; 马余强
2001-01-01
We apply the principle of maximum entropy to consider the excluded volume effect on the phase separation of binary mixtures consisting of hard spheres with two different diameters. We show that a critical volume fraction of hard spheres exists locating the packing of large spheres. In particular, through numerical calculation, we have found that the critical volume fraction becomes lower when the ratio α = σ1/σ2 of large-to-small sphere diameters increases, but becomes higher when the ratio of the large sphere volume fraction to the total volume fraction of large and small spheres increases.
Fractional diffusion: recovering the distributed fractional derivative from overposed data
Rundell, W.; Zhang, Z.
2017-03-01
There has been considerable recent study in ‘subdiffusion’ models that replace the standard parabolic equation model by a one with a fractional derivative in the time variable. There are many ways to look at this newer approach and one such is to realize that the order of the fractional derivative is related to the time scales of the underlying diffusion process. This raises the question of what order α of derivative should be taken and if a single value actually suffices. This has led to models that combine a finite number of these derivatives each with a different fractional exponent {αk} and different weighting value c k to better model a greater possible range of time scales. Ultimately, one wants to look at a situation that combines derivatives in a continuous way—the so-called distributional model with parameter μ ≤ft(α \\right) . However all of this begs the question of how one determines this ‘order’ of differentiation. Recovering a single fractional value has been an active part of the process from the beginning of fractional diffusion modeling and if this is the only unknown then the markers left by the fractional order derivative are relatively straightforward to determine. In the case of a finite combination of derivatives this becomes much more complex due to the more limited analytic tools available for such equations, but recent progress in this direction has been made, (Li et al 2015 Appl. Math. Comput. 257 381–97, Li and Yamamoto 2015 Appl. Anal. 94 570–9). This paper considers the full distributional model where the order is viewed as a function μ ≤ft(α \\right) on the interval (0, 1]. We show existence, uniqueness and regularity for an initial-boundary value problem including an important representation theorem in the case of a single spatial variable. This is then used in the inverse problem of recovering the distributional coefficient μ ≤ft(α \\right) from a time trace of the solution and a uniqueness result is
Astuti, Valerio; Rovelli, Carlo
2016-01-01
Building on a technical result by Brunnemann and Rideout on the spectrum of the Volume operator in Loop Quantum Gravity, we show that the dimension of the space of the quadrivalent states --with finite-volume individual nodes-- describing a region with total volume smaller than $V$, has \\emph{finite} dimension, bounded by $V \\log V$. This allows us to introduce the notion of "volume entropy": the von Neumann entropy associated to the measurement of volume.
Dividing Fractions: A Pedagogical Technique
Lewis, Robert
2016-01-01
When dividing one fraction by a second fraction, invert, that is, flip the second fraction, then multiply it by the first fraction. To multiply fractions, simply multiply across the denominators, and multiply across the numerators to get the resultant fraction. So by inverting the division of fractions it is turned into an easy multiplication of…
Fractional graph theory a rational approach to the theory of graphs
Scheinerman, Edward R
2013-01-01
A unified treatment of the most important results in the study of fractional graph concepts, this volume explores the various ways in which integer-valued concepts can be modified to derive nonintegral values. It begins with the general fractional theory of hypergraphs and presents in-depth coverage of fundamental and advanced topics. Subjects include fractional matching, fractional coloring, fractional edge coloring, fractional arboricity via matroid methods, and fractional isomorphism. The final chapter examines additional topics such as fractional domination, fractional intersection numbers
Large deviations for fractional Poisson processes
Beghin, Luisa
2012-01-01
We present large deviation results for two versions of fractional Poisson processes: the main version which is a renewal process, and the alternative version where all the random variables are weighted Poisson distributed. We also present a sample path large deviation result for suitably normalized counting processes; finally we show how this result can be applied to the two versions of fractional Poisson processes considered in this paper.
Neutron Imaging Calibration to Measure Void Fraction
Energy Technology Data Exchange (ETDEWEB)
Geoghegan, Patrick J [ORNL; Bilheux, Hassina Z [ORNL; Sharma, Vishaldeep [ORNL; Fricke, Brian A [ORNL
2015-01-01
Void fraction is an intuitive parameter that describes the fraction of vapor in a two-phase flow. It appears as a key variable in most heat transfer and pressure drop correlations used to design evaporating and condensing heat exchangers, as well as determining charge inventory in refrigeration systems. Void fraction measurement is not straightforward, however, and assumptions on the invasiveness of the measuring technique must be made. Neutron radiography or neutron imaging has the potential to be a truly non-invasive void fraction measuring technique but has until recently only offered qualitative descriptions of two-phase flow, in terms of flow maldistributions, for example. This paper describes the calibration approach necessary to employ neutron imaging to measure steady-state void fraction. Experiments were conducted at the High Flux Isotope Reactor (HFIR) Cold Guide 1D neutron imaging facility at Oak Ridge National Laboratory (ORNL), Oak Ridge, TN, USA.
Fractional Pure Birth Processes
Orsingher, Enzo; 10.3150/09-BEJ235
2010-01-01
We consider a fractional version of the classical non-linear birth process of which the Yule-Furry model is a particular case. Fractionality is obtained by replacing the first-order time derivative in the difference-differential equations which govern the probability law of the process, with the Dzherbashyan-Caputo fractional derivative. We derive the probability distribution of the number $ \\mathcal{N}_\
Fractional vortex Hilbert's Hotel
Gbur, Greg
2015-01-01
We demonstrate how the unusual mathematics of transfinite numbers, in particular a nearly perfect realization of Hilbert's famous hotel paradox, manifests in the propagation of light through fractional vortex plates. It is shown how a fractional vortex plate can be used, in principle, to create any number of "open rooms," i.e. topological charges, simultaneously. Fractional vortex plates are therefore demonstrated to create a singularity of topological charge, in which the vortex state is completely undefined and in fact arbitrary.
Fractional Electromagnetic Waves
Gómez, J F; Bernal, J J; Tkach, V I; Guía, M
2011-01-01
In the present work we consider the electromagnetic wave equation in terms of the fractional derivative of the Caputo type. The order of the derivative being considered is 0 <\\gamma<1. A new parameter \\sigma, is introduced which characterizes the existence of the fractional components in the system. We analyze the fractional derivative with respect to time and space, for \\gamma = 1 and \\gamma = 1/2 cases.
The fractional Poisson process and the inverse stable subordinator
Meerschaert, Mark M; Vellaisamy, P
2010-01-01
The fractional Poisson process is a renewal process with Mittag-Leffler waiting times. Its distributions solve a time-fractional analogue of the Kolmogorov forward equation for a Poisson process. This paper shows that a traditional Poisson process, with the time variable replaced by an independent inverse stable subordinator, is also a fractional Poisson process. This result unifies the two main approaches in the stochastic theory of time-fractional diffusion equations. The equivalence extends to a broad class of renewal processes that include models for tempered fractional diffusion, and distributed-order (e.g., ultraslow) fractional diffusion.
Matrix approach to discrete fractional calculus II: Partial fractional differential equations
Podlubny, Igor; Chechkin, Aleksei; Skovranek, Tomas; Chen, YangQuan; Vinagre Jara, Blas M.
2009-05-01
A new method that enables easy and convenient discretization of partial differential equations with derivatives of arbitrary real order (so-called fractional derivatives) and delays is presented and illustrated on numerical solution of various types of fractional diffusion equation. The suggested method is the development of Podlubny's matrix approach [I. Podlubny, Matrix approach to discrete fractional calculus, Fractional Calculus and Applied Analysis 3 (4) (2000) 359-386]. Four examples of numerical solution of fractional diffusion equation with various combinations of time-/space-fractional derivatives (integer/integer, fractional/integer, integer/fractional, and fractional/fractional) with respect to time and to the spatial variable are provided in order to illustrate how simple and general is the suggested approach. The fifth example illustrates that the method can be equally simply used for fractional differential equations with delays. A set of MATLAB routines for the implementation of the method as well as sample code used to solve the examples have been developed.
Yang, Weitao; Mori-Sánchez, Paula; Cohen, Aron J
2013-09-14
The exact conditions for density functionals and density matrix functionals in terms of fractional charges and fractional spins are known, and their violation in commonly used functionals has been shown to be the root of many major failures in practical applications. However, approximate functionals are designed for physical systems with integer charges and spins, not in terms of the fractional variables. Here we develop a general framework for extending approximate density functionals and many-electron theory to fractional-charge and fractional-spin systems. Our development allows for the fractional extension of any approximate theory that is a functional of G(0), the one-electron Green's function of the non-interacting reference system. The extension to fractional charge and fractional spin systems is based on the ensemble average of the basic variable, G(0). We demonstrate the fractional extension for the following theories: (1) any explicit functional of the one-electron density, such as the local density approximation and generalized gradient approximations; (2) any explicit functional of the one-electron density matrix of the non-interacting reference system, such as the exact exchange functional (or Hartree-Fock theory) and hybrid functionals; (3) many-body perturbation theory; and (4) random-phase approximations. A general rule for such an extension has also been derived through scaling the orbitals and should be useful for functionals where the link to the Green's function is not obvious. The development thus enables the examination of approximate theories against known exact conditions on the fractional variables and the analysis of their failures in chemical and physical applications in terms of violations of exact conditions of the energy functionals. The present work should facilitate the calculation of chemical potentials and fundamental bandgaps with approximate functionals and many-electron theories through the energy derivatives with respect to the
Directory of Open Access Journals (Sweden)
Marcelo Luiz Campos Vieira
2009-04-01
Full Text Available FUNDAMENTO: O ecocardiograma tridimensional em tempo real (ECO 3D e a tomografia computadorizada ultra-rápida (CT são dois novos métodos de análise da fração de ejeção e dos volumes do VE. OBJETIVO: Comparar as medidas da FEVE e dos volumes do VE aferidos pelo ECO 3D e pela CT ultra-rápida. MÉTODOS: Foram estudados pelo ECO 3D e pela CT ultra-rápida de 64 cortes, 39 pacientes consecutivos (27 homens, média etária de 57±12 anos. Foram analisados: FEVE e volumes do VE. Análise estatística: coeficiente de correlação (r: Pearson, teste de Bland & Altman, teste de regressão linear, 95 % IC, pFUNDAMENTO: La ecocardiografía tridimensional en tiempo real (Eco-3DTR y la tomografía computarizada ultrarrápida (TC ultrarrápida son dos nuevos métodos de análisis de la fracción de eyección (FE y de los volúmenes del ventrículo izquierdo (VI. OBJETIVO: Comparar las mediciones de la fracción de eyección del ventrículo izquierdo (FEVI y de los volúmenes del VI apurados por la Eco-3DTR y por la TC ultrarrápida. MÉTODOS: Se estudiaron, mediante la Eco-3DTR y la TC ultrarrápida de 64 cortes, a 39 pacientes consecutivos (27 varones, promedio de edad de 57±12 años. Se analizaron: FEVI y volúmenes del VI. Análisis estadístico: coeficiente de correlación (r: Pearson, prueba de Bland & Altman, prueba de regresión lineal, 95 % IC, pBACKGROUND: Real-time three-dimensional echocargiography (RT-3D-Echo and ultrafast computed tomography (CT are two novel methods for the analysis of LV ejection fraction and volumes. OBJECTIVE: To compare LVEF and volume measurements as obtained using RT-3D-Echo and ultrafast CT. METHODS: Thirty nine consecutive patients (27 men, mean age of 57±12 years were studied using RT-3D-Echo and 64-slice ultrafast CT. LVEF and LV volumes were analyzed. Statistical analysis: coefficient of correlation (r: Pearson, Bland-Altman analysis, linear regression analysis, 95% CI, p<0.05. RESULTS: RT-3D
Wang, Lijuan; Yan, Yong; Wang, Xue; Wang, Tao
2017-03-01
Input variable selection is an essential step in the development of data-driven models for environmental, biological and industrial applications. Through input variable selection to eliminate the irrelevant or redundant variables, a suitable subset of variables is identified as the input of a model. Meanwhile, through input variable selection the complexity of the model structure is simplified and the computational efficiency is improved. This paper describes the procedures of the input variable selection for the data-driven models for the measurement of liquid mass flowrate and gas volume fraction under two-phase flow conditions using Coriolis flowmeters. Three advanced input variable selection methods, including partial mutual information (PMI), genetic algorithm-artificial neural network (GA-ANN) and tree-based iterative input selection (IIS) are applied in this study. Typical data-driven models incorporating support vector machine (SVM) are established individually based on the input candidates resulting from the selection methods. The validity of the selection outcomes is assessed through an output performance comparison of the SVM based data-driven models and sensitivity analysis. The validation and analysis results suggest that the input variables selected from the PMI algorithm provide more effective information for the models to measure liquid mass flowrate while the IIS algorithm provides a fewer but more effective variables for the models to predict gas volume fraction.
Energy Technology Data Exchange (ETDEWEB)
Ziada, G.; Abdel-Dayem, H.M.; Higazy, E.; Mohamed, M.M.; Bahar, R.; Hayat, N.; Yousof, A.M.
1987-03-01
A dual gated tomography (DGT) program for end systolic and end diastolic acquisition and subsequent processing for calculation of LVEF, end diastolic and end systolic volumes (EDV, ESV) has been evaluated in 20 healthy volunteers (25 years-40 years) and 45 patients (25 years-60 years): 20 with ischaemic heart disease and 25 with valvular heart disease (VHD). All had biplane multigated blood pool (MUGA) studies in the 40/sup 0/ LAO projection using in vivo /sup 99m/Tc-R BCs, immediately followed by DG. The results in the patients group were correlated with contrast ventriculography (CV). In the volunteer group, the normal values for LVEF, EDV and ESV measured with DGT were found to be 63%+10%, 91 ml + 6 ml and 30 ml + 6ml and r value for the LVEF=0.91 compared with MUGA. In the IHD group, r values compared with CV were 0.915 and 0.97 for the EDV and ESV and 0.934 for the LVEF. Compared with the MUGA, the r value for LVEF was 0.883. In the VHD group, r values were 0.98 for both the EDV and ESV and 0.948 for the LVEF (P<0.002) compared with CV and 0.789 for the LVEF compared with the MUGA. We feel that DGT is an accurate and reproducible technique for LV function measurements.
Institute of Scientific and Technical Information of China (English)
张帆; 刘君; 陈飙松; 钟万勰
2015-01-01
A commonly-used gradient reconstruction procedure for the second-order cell-centered finite volume method is to calculate the element gradient by its vertex variables.The key issue of this method is to construct the local linearly distributed vertex variables by their adj acent elements' cell-centered variables. Using weighted least squares method for vertex variables reconstruction, considering the fact that the cell-centered variables are non-linear distribution,inversely distance weight is applied to estimate the different influences of the elements in various positions.In order to deal with the over-estimation of vertex variables on perturbed or curved grids,a new clipping method is implemented.Test cases use high-aspect-ratio,perturbed or curved grids which are commonly applied to the boundary layer flow simulations with high Reynolds number.The presented method is compared with weighted averaging method and pseudo-Laplacian method.Numerical results show that better accuracy is attained by presented inversely distance weighted least squares method,and the over-estimation of vertex variables on perturbed or curved grids is eliminated by the clipping method suggested here.%根据网格格点变量计算单元变量梯度是二阶空间精度格心型有限体积法梯度重构的常用方法，该方法的关键是根据格点的邻接单元格心变量构造满足局部线性分布的格点变量。采用加权最小二乘法进行格点变量重构，考虑实际格心变量的非线性分布，提出采用距离反比加权体现不同位置单元对格点变量的影响程度差异；针对扰动或弯曲网格中的格点变量重构出现极值的现象，采用了新的限制方法。采用高雷诺数边界层流动计算中常见的大长宽比、扰动/弯曲网格进行测试，将提出的方法与通常采用的加权平均方法和拟拉普拉斯方法进行对比。算例结果显示距离反比加权的最小二乘法重构精度较好，提出
Fractional and noncommutative spacetimes
Arzano, M.; Calcagni, M.; Oriti, D.; Scalisi, M.
2011-01-01
We establish a mapping between fractional and noncommutative spacetimes in configuration space. Depending on the scale at which the relation is considered, there arise two possibilities. For a fractional spacetime with log-oscillatory measure, the effective measure near the fundamental scale determi
Can Kindergartners Do Fractions?
Cwikla, Julie
2014-01-01
Mathematics professor Julie Cwikla decided that she needed to investigate young children's understandings and see what precurricular partitioning notions young minds bring to the fraction table. Cwikla realized that only a handful of studies have examined how preschool-age and early elementary school-age students solve fraction problems (Empson…
Can Kindergartners Do Fractions?
Cwikla, Julie
2014-01-01
Mathematics professor Julie Cwikla decided that she needed to investigate young children's understandings and see what precurricular partitioning notions young minds bring to the fraction table. Cwikla realized that only a handful of studies have examined how preschool-age and early elementary school-age students solve fraction problems (Empson…
Wilkerson, Trena L.; Bryan, Tommy; Curry, Jane
2012-01-01
This article describes how using candy bars as models gives sixth-grade students a taste for learning to represent fractions whose denominators are factors of twelve. Using paper models of the candy bars, students explored and compared fractions. They noticed fewer different representations for one-third than for one-half. The authors conclude…
Categories of Fractions Revisited
Fritz, Tobias
2008-01-01
The theory of categories of fractions as originally developed by Gabriel and Zisman is reviewed in a pedagogical manner giving detailed proofs of all statements. A weakening of the category of fractions axioms used by Higson is discussed and shown to be equivalent to the original axioms.
Energy Technology Data Exchange (ETDEWEB)
Bajona-Xandri, C.; Martinez-Legaz, J.E.
1994-12-31
This paper studies the minimax fractional programming problem, assuming quasiconvexity of the objective function, under the lower subdifferentiability viewpoint. Necessary and sufficient optimality conditions and dual properties are found. We present applications of this theory to find the Pareto efficient solutions of a multiobjective fractional problem and to solve several economic models.
Glasby, John S
1974-01-01
The Nebular Variables focuses on the nebular variables and their characteristics. Discussions are organized by type of nebular variable, namely, RW Aurigae stars, T Orionis stars, T Tauri stars, and peculiar nebular objects. Topics range from light variations of the stars to their spectroscopic and physical characteristics, spatial distribution, interaction with nebulosity, and evolutionary features. This volume is divided into four sections and consists of 25 chapters, the first of which provides general information on nebular variables, including their stellar associations and their classifi
Variable volume combustor with aerodynamic support struts
Energy Technology Data Exchange (ETDEWEB)
Ostebee, Heath Michael; Johnson, Thomas Edward; Stewart, Jason Thurman; Keener, Christopher Paul
2017-03-07
The present application provides a combustor for use with a gas turbine engine. The combustor may include a number of micro-mixer fuel nozzles and a fuel injection system for providing a flow of fuel to the micro-mixer fuel nozzles. The fuel injection system may include a number of support struts supporting the fuel nozzles and providing the flow of fuel therethrough. The support struts may include an aerodynamic contoured shape so as to distribute evenly a flow of air to the micro-mixer fuel nozzles.
Jauncey, DL; King, EA; Bignall, HE; Lovell, JEJ; Kedziora-Chudczer, L; Tzioumis, AK; Tingay, SJ; Macquart, JP; McCulloch, PM
2003-01-01
Flux density monitoring data at 2.3 and 8.4 GHz is presented for a sample of 33 southern hemisphere GPS sources, drawn from the 2.7 GHz Parkes survey. This monitoring data, together with VLBI monitoring data, shows that a small fraction of these sources, similar to10%, vary. Their variability falls
Jauncey, DL; King, EA; Bignall, HE; Lovell, JEJ; Kedziora-Chudczer, L; Tzioumis, AK; Tingay, SJ; Macquart, JP; McCulloch, PM
2003-01-01
Flux density monitoring data at 2.3 and 8.4 GHz is presented for a sample of 33 southern hemisphere GPS sources, drawn from the 2.7 GHz Parkes survey. This monitoring data, together with VLBI monitoring data, shows that a small fraction of these sources, similar to10%, vary. Their variability falls
Fractional calculus in bioengineering.
Magin, Richard L
2004-01-01
Fractional calculus (integral and differential operations of noninteger order) is not often used to model biological systems. Although the basic mathematical ideas were developed long ago by the mathematicians Leibniz (1695), Liouville (1834), Riemann (1892), and others and brought to the attention of the engineering world by Oliver Heaviside in the 1890s, it was not until 1974 that the first book on the topic was published by Oldham and Spanier. Recent monographs and symposia proceedings have highlighted the application of fractional calculus in physics, continuum mechanics, signal processing, and electromagnetics, but with few examples of applications in bioengineering. This is surprising because the methods of fractional calculus, when defined as a Laplace or Fourier convolution product, are suitable for solving many problems in biomedical research. For example, early studies by Cole (1933) and Hodgkin (1946) of the electrical properties of nerve cell membranes and the propagation of electrical signals are well characterized by differential equations of fractional order. The solution involves a generalization of the exponential function to the Mittag-Leffler function, which provides a better fit to the observed cell membrane data. A parallel application of fractional derivatives to viscoelastic materials establishes, in a natural way, hereditary integrals and the power law (Nutting/Scott Blair) stress-strain relationship for modeling biomaterials. In this review, I will introduce the idea of fractional operations by following the original approach of Heaviside, demonstrate the basic operations of fractional calculus on well-behaved functions (step, ramp, pulse, sinusoid) of engineering interest, and give specific examples from electrochemistry, physics, bioengineering, and biophysics. The fractional derivative accurately describes natural phenomena that occur in such common engineering problems as heat transfer, electrode/electrolyte behavior, and sub
Social Trust and Fractionalization:
DEFF Research Database (Denmark)
Bjørnskov, Christian
2008-01-01
This paper takes a closer look at the importance of fractionalization for the creation of social trust. It first argues that the determinants of trust can be divided into two categories: those affecting individuals' trust radii and those affecting social polarization. A series of estimates using...... a much larger country sample than in previous literature confirms that fractionalization in the form of income inequality and political diversity adversely affects social trust while ethnic diversity does not. However, these effects differ systematically across countries, questioning standard...... interpretations of the influence of fractionalization on trust....
Directory of Open Access Journals (Sweden)
Melissa Trotman-Lucas
2017-07-01
Full Text Available Animal models are essential for understanding the pathology of stroke and investigating potential treatments. However, in vivo stroke models are associated, particularly in mice, with high variability in lesion volume. We investigated whether a surgical refinement where reperfusion is not reliant on the Circle of Willis reduced outcome variability. Mice underwent 60 min of transient middle cerebral artery occlusion avoiding ligation of the external carotid artery. During reperfusion, the common carotid artery was either ligated (standard approach, or it was repaired to allow re-establishment of blood flow through the common carotid artery. All mice underwent MRI scanning for assessment of infarct volume, apparent diffusion coefficient and fractional anisotropy, along with terminal assessment of infarct volume by 2,3,5-triphenyltetrazolium chloride (TTC staining. Repairing the common carotid artery following middle cerebral artery occlusion enhanced reperfusion (P<0.01 and reduced the variability seen in both total (histological analysis, P=0.008; T2-weighted MRI, P=0.015 and core (diffusion tensor MRI, P=0.043 lesion volume. Avoiding external carotid artery ligation may improve animal wellbeing, through reduced weight loss, while using an alternative surgical approach that enabled reperfusion through the common carotid artery decreased the variability in lesion volume seen within groups.
Goodrich, Christopher
2015-01-01
This text provides the first comprehensive treatment of the discrete fractional calculus. Experienced researchers will find the text useful as a reference for discrete fractional calculus and topics of current interest. Students who are interested in learning about discrete fractional calculus will find this text to provide a useful starting point. Several exercises are offered at the end of each chapter and select answers have been provided at the end of the book. The presentation of the content is designed to give ample flexibility for potential use in a myriad of courses and for independent study. The novel approach taken by the authors includes a simultaneous treatment of the fractional- and integer-order difference calculus (on a variety of time scales, including both the usual forward and backwards difference operators). The reader will acquire a solid foundation in the classical topics of the discrete calculus while being introduced to exciting recent developments, bringing them to the frontiers of the...
Fractional Derivative Cosmology
Roberts, Mark D
2009-01-01
The degree by which a function can be differentiated need not be restricted to integer values. Usually most of the field equations of physics are taken to be second order, curiosity asks what happens if this is only approximately the case and the field equations are nearly second order. For Robertson-Walker cosmology there is a simple fractional modification of the Friedman and conservation equations. In general fractional gravitational equations similar to Einstein's are hard to define as this requires fractional derivative geometry. What fractional derivative geometry might entail is briefly looked at and it turns out that even asking very simple questions in two dimensions leads to ambiguous or intractable results. A two dimensional line element which depends on the Gamma-function is looked at.
Energy Technology Data Exchange (ETDEWEB)
Schimek-Jasch, Tanja; Prokic, Vesna; Doll, Christian; Grosu, Anca-Ligia; Nestle, Ursula [University Medical Center Freiburg, Department of Radiation Oncology, Freiburg (Germany); German Cancer Research Center (DKFZ), Heidelberg (Germany); German Cancer Consortium (DKTK) partner site: Freiburg, Heidelberg (Germany); Troost, Esther G.C. [Maastricht University Medical Centre, Department of Radiation Oncology (MAASTRO), GROW School for Oncology and Developmental Biology, Maastricht (Netherlands); Ruecker, Gerta [University Medical Center Freiburg, Institute for Medical Biometry and Statistics, Centre for Medical Biometry and Medical Informatics, Freiburg (Germany); Avlar, Melanie [German Cancer Research Center (DKFZ), Heidelberg (Germany); Duncker-Rohr, Viola [Ortenau-Klinikum Offenburg-Gengenbach, Department of Radiation Oncology, Gengenbach (Germany); Mix, Michael [University Medical Center Freiburg, Department of Nuclear Medicine, Freiburg (Germany); German Cancer Research Center (DKFZ), Heidelberg (Germany); German Cancer Consortium (DKTK) partner site: Freiburg, Heidelberg (Germany)
2015-02-10
Interobserver variability in the definition of target volumes (TVs) is a well-known confounding factor in (multicentre) clinical studies employing radiotherapy. Therefore, detailed contouring guidelines are provided in the prospective randomised multicentre PET-Plan (NCT00697333) clinical trial protocol. This trial compares strictly FDG-PET-based TV delineation with conventional TV delineation in patients with locally advanced non-small cell lung cancer (NSCLC). Despite detailed contouring guidelines, their interpretation by different radiation oncologists can vary considerably, leading to undesirable discrepancies in TV delineation. Considering this, as part of the PET-Plan study quality assurance (QA), a contouring dummy run (DR) consisting of two phases was performed to analyse the interobserver variability before and after teaching. In the first phase of the DR (DR1), radiation oncologists from 14 study centres were asked to delineate TVs as defined by the study protocol (gross TV, GTV; and two clinical TVs, CTV-A and CTV-B) in a test patient. A teaching session was held at a study group meeting, including a discussion of the results focussing on discordances in comparison to the per-protocol solution. Subsequently, the second phase of the DR (DR2) was performed in order to evaluate the impact of teaching. Teaching after DR1 resulted in a reduction of absolute TVs in DR2, as well as in better concordance of TVs. The Overall Kappa(κ) indices increased from 0.63 to 0.71 (GTV), 0.60 to 0.65 (CTV-A) and from 0.59 to 0.63 (CTV-B), demonstrating improvements in overall interobserver agreement. Contouring DRs and study group meetings as part of QA in multicentre clinical trials help to identify misinterpretations of per-protocol TV delineation. Teaching the correct interpretation of protocol contouring guidelines leads to a reduction in interobserver variability and to more consistent contouring, which should consequently improve the validity of the overall study
The Space-Fractional Poisson Process
Orsingher, Enzo
2011-01-01
In this paper we introduce the space-fractional Poisson process whose state probabilities $p_k^\\alpha(t)$, $t>0$, $\\alpha \\in (0,1]$, are governed by the equations $(\\mathrm d/\\mathrm dt)p_k(t) = -\\lambda^\\alpha (1-B)p_k^\\alpha(t)$, where $(1-B)^\\alpha$ is the fractional difference operator found in the study of time series analysis. We explicitly obtain the distributions $p_k^\\alpha(t)$, the probability generating functions $G_\\alpha(u,t)$, which are also expressed as distributions of the minimum of i.i.d.\\ uniform random variables. The comparison with the time-fractional Poisson process is investigated and finally, we arrive at the more general space-time fractional Poisson process of which we give the explicit distribution.
Digestion kinetics of carbohydrate fractions of citrus by-products.
Lashkari, Saman; Taghizadeh, Akbar
2015-01-01
The present experiment was carried out to determine the digestion kinetics of carbohydrate fractions of citrus by-products. Grapefruit pulp (GP), lemon pulp (LE), lime pulp (LI) and orange pulp (OP) were the test feed. Digestion kinetic of whole citrus by-products and neutral detergent fiber (NDF) fraction and acid detergent fiber (ADF) fractions of citrus by-products were measured using the in vitro gas production technique. Fermentation kinetics of the neutral detergent soluble carbohydrates (NDSC) fraction and hemicelluloses were calculated using a curve subtraction. The fermentation rate of whole was the highest for the LE (p fractions. There was no significant difference among potential gas production (A) volumes of whole test feeds (p fractions of citrus by-products have high potential for degradability. It could also be concluded that carbohydrate fractions of citrus by-products have remarkable difference in digestion kinetics and digestive behavior.
Energy Technology Data Exchange (ETDEWEB)
Wong, O; Lo, G; Yuan, J; Law, M; Ding, A; Cheng, K; Chan, K; Cheung, K; Yu, S [Hong Kong Sanatorium & Hospital, Hong Kong (Hong Kong)
2015-06-15
Purpose: There is growing interests in applying MR-simulator(MR-sim) in radiotherapy but MR images subject to hardware, patient and pulse sequence dependent geometric distortion that may potentially influence target definition. This study aimed to evaluate the influence on head-and-neck tissue delineation, in terms of positional and volumetric variability, of two T1-weighted(T1w) MR sequences on a 1.5T MR-sim Methods: Four healthy volunteers were scanned (4 scans for each on different days) using both spin-echo (3DCUBE, TR/TE=500/14ms, TA=183s) and gradient-echo sequences (3DFSPGR, TE/TR=7/4ms, TA=173s) with identical coverage, voxel-size(0.8×0.8×1.0mm3), receiver-bandwidth(62.5kHz/pix) and geometric correction on a 1.5T MR-sim immobilized with personalized thermoplastic cast and head-rest. Under this setting, similar T1w contrast and signal-to-noise ratio were obtained, and factors other than sequence that might bias image distortion and tissue delineation were minimized. VOIs of parotid gland(PGR, PGL), pituitary gland(PIT) and eyeballs(EyeL, EyeR) were carefully drawn, and inter-scan coefficient-of-variation(CV) of VOI centroid position and volume were calculated for each subject. Mean and standard deviation(SD) of the CVs for four subjects were compared between sequences using Wilcoxon ranksum test. Results: The mean positional(<4%) and volumetric(<7%) CVs varied between tissues, majorly dependent on tissue inherent properties like volume, location, mobility and deformability. Smaller mean volumetric CV was found in 3DCUBE, probably due to its less proneness to tissue susceptibility, but only PGL showed significant difference(P<0.05). Positional CVs had no significant differences for all VOIs(P>0.05) between sequences, suggesting volumetric variation might be more sensitive to sequence-dependent delineation difference. Conclusion: Although 3DCUBE is considered less prone to tissue susceptibility-induced artifact and distortion, our preliminary data showed
New Fractional Complex Transform for Conformable Fractional Partial Differential Equations
Directory of Open Access Journals (Sweden)
Çenesiz Y.
2016-12-01
Full Text Available Conformable fractional complex transform is introduced in this paper for converting fractional partial differential equations to ordinary differential equations. Hence analytical methods in advanced calculus can be used to solve these equations. Conformable fractional complex transform is implemented to fractional partial differential equations such as space fractional advection diffusion equation and space fractional telegraph equation to obtain the exact solutions of these equations.
Institute of Scientific and Technical Information of China (English)
肖正刚; 应三九; 徐复铭
2014-01-01
To study the combustion stability and safety of consolidation propellants under the conditions of variable combustion-chamber volume and to discuss the effects of different surface-treatment methods on progressive burning,high temperature solvent vapor of alcohol/acetone were used to consolidate double-base oblate sphere propellant standard grains plasticized with tri-ethyeneglycol dinitrate (TEGN ) to propellants charge with high compaction density of 1 .3 5 g·cm-3 after pre-deconsolidation treatment.The obtained consolidated charges were coated by pure nitrocellulose gel,mixed nitrocellulose gel containing ignition sensitizer and mixed nitro-cellulose gel containing the deterrents,respectively.Interrupted burning experiments of consolidated propellant charges were carried out in a semi-closed test rig with variable volume, and the pressure-time history of gas generation during the interrupted burning was recorded by the pressure transducer.The effect of different surface treatment method on the burning progressivity of prepared samples was discussed based on the deduced dynamic vivacity data. Compared with coated consolidated with pure nitrocellulose gel,it is easy to be ignited for the samples coated by the mixed nitrocellulose gel containing ignition sensitizer.In contrast,the prepared samples coated by deterred nitrocellulose gel indicates an ignition delay;the peak of dynamic vivacity decreases a little,and the progressive burning is good.Results show that appropriate surface treatment method can inhibit the initial dynamic vivacity of consolidated charges and obtain the burning progressivity.%为研究压实装药在变容情况下的动态燃烧稳定性、安全性能及不同表面处理方法对动态燃烧渐增性能的影响，将太根小粒药表面进行解体预处理后，采用乙醇/丙酮高温热蒸汽软化法将其压实成堆积密度为1.35 g·cm-3的药柱，再进行表面处理，得到待测的压实药柱样品。利用设计自制
Jeon, Jae-Hyung; Metzler, Ralf
2010-02-01
Motivated by subdiffusive motion of biomolecules observed in living cells, we study the stochastic properties of a non-Brownian particle whose motion is governed by either fractional Brownian motion or the fractional Langevin equation and restricted to a finite domain. We investigate by analytic calculations and simulations how time-averaged observables (e.g., the time-averaged mean-squared displacement and displacement correlation) are affected by spatial confinement and dimensionality. In particular, we study the degree of weak ergodicity breaking and scatter between different single trajectories for this confined motion in the subdiffusive domain. The general trend is that deviations from ergodicity are decreased with decreasing size of the movement volume and with increasing dimensionality. We define the displacement correlation function and find that this quantity shows distinct features for fractional Brownian motion, fractional Langevin equation, and continuous time subdiffusion, such that it appears an efficient measure to distinguish these different processes based on single-particle trajectory data.
Eto, Minoru; Gudnason, Sven Bjarke; Konishi, Kenichi; Nagashima, Takayuki; Nitta, Muneto; Ohashi, Keisuke; Vinci, Walter
2009-01-01
We study what might be called fractional vortices, vortex configurations with the minimum winding from the viewpoint of their topological stability, but which are characterized by various notable substructures in the transverse energy distribution. The fractional vortices occur in diverse Abelian or non-Abelian generalizations of the Higgs model. The global and local features characterizing these are studied, and we identify the two crucial ingredients for their occurrence - the vacuum degeneracy leading to non-trivial vacuum moduli M, and the BPS nature of the vortices. Fractional vortices are further classified into two kinds. The first type of such vortices appear when M has orbifold Z_n singularities; the second type occurs in systems in which the vacuum moduli space M possesses either a deformed geometry or some singularity. These general features are illustrated with several concrete models.
Biswas, Karabi; Caponetto, Riccardo; Mendes Lopes, António; Tenreiro Machado, José António
2017-01-01
This book focuses on two specific areas related to fractional order systems – the realization of physical devices characterized by non-integer order impedance, usually called fractional-order elements (FOEs); and the characterization of vegetable tissues via electrical impedance spectroscopy (EIS) – and provides readers with new tools for designing new types of integrated circuits. The majority of the book addresses FOEs. The interest in these topics is related to the need to produce “analogue” electronic devices characterized by non-integer order impedance, and to the characterization of natural phenomena, which are systems with memory or aftereffects and for which the fractional-order calculus tool is the ideal choice for analysis. FOEs represent the building blocks for designing and realizing analogue integrated electronic circuits, which the authors believe hold the potential for a wealth of mass-market applications. The freedom to choose either an integer- or non-integer-order analogue integrator...
Fractional and noncommutative spacetimes
Arzano, Michele; Calcagni, Gianluca; Oriti, Daniele; Scalisi, Marco
2011-12-01
We establish a mapping between fractional and noncommutative spacetimes in configuration space. Depending on the scale at which the relation is considered, there arise two possibilities. For a fractional spacetime with log-oscillatory measure, the effective measure near the fundamental scale determining the log-period coincides with the nonrotation-invariant but cyclicity-preserving measure of κ-Minkowski spacetime. At scales larger than the log-period, the fractional measure is averaged and becomes a power law with real exponent. This can be also regarded as the cyclicity-inducing measure in a noncommutative spacetime defined by a certain nonlinear algebra of the coordinates, which interpolates between κ-Minkowski and canonical spacetime. These results are based upon a braiding formula valid for any nonlinear algebra which can be mapped onto the Heisenberg algebra.
Fractional and noncommutative spacetimes
Arzano, Michele; Oriti, Daniele; Scalisi, Marco
2011-01-01
We establish a mapping between fractional and noncommutative spacetimes in configuration space. Depending on the scale at which the relation is considered, there arise two possibilities. For a fractional spacetime with log-oscillatory measure, the effective measure near the fundamental scale determining the log-period coincides with the non-rotation-invariant but cyclicity-preserving measure of \\kappa-Minkowski. At scales larger than the log-period, the fractional measure is averaged and becomes a power-law with real exponent. This can be also regarded as the cyclicity-inducing measure in a noncommutative spacetime defined by a certain nonlinear algebra of the coordinates, which interpolates between \\kappa-Minkowski and canonical spacetime. These results are based upon a braiding formula valid for any nonlinear algebra which can be mapped onto the Heisenberg algebra.
Energy Technology Data Exchange (ETDEWEB)
Edelman, Mark, E-mail: edelman@cims.nyu.ed [Courant Institute of Mathematical Sciences, New York University, 251 Mercer St., New York, NY 10012 (United States)] [Department of Physics, Stern College at Yeshiva University, 245 Lexington Avenue, New York, NY 10016 (United States); Tarasov, Vasily E. [Courant Institute of Mathematical Sciences, New York University, 251 Mercer St., New York, NY 10012 (United States)] [Skobeltsyn Institute of Nuclear Physics, Moscow State University, Moscow 119991 (Russian Federation)
2009-12-28
Properties of the phase space of the standard map with memory are investigated. This map was obtained from a kicked fractional differential equation. Depending on the value of the map parameter and the fractional order of the derivative in the original differential equation, this nonlinear dynamical system demonstrates attractors (fixed points, stable periodic trajectories, slow converging and slow diverging trajectories, ballistic trajectories, and fractal-like structures) and/or chaotic trajectories. At least one type of fractal-like sticky attractors in the chaotic sea was observed.
Prognostic, quantitative histopathologic variables in lobular carcinoma of the breast
DEFF Research Database (Denmark)
Ladekarl, M; Sørensen, Flemming Brandt
1993-01-01
BACKGROUND: A retrospective investigation of 53 consecutively treated patients with operable lobular carcinoma of the breast, with a median follow-up of 6.6 years, was performed to examine the prognostic value of quantitative histopathologic parameters. METHODS: The measurements were performed...... in routinely processed histologic sections using a simple, unbiased technique for the estimation of the three-dimensional mean nuclear volume (vv(nuc)). In addition, quantitative estimates were obtained of the mitotic index (MI), the nuclear index (NI), the nuclear volume fraction (Vv(nuc/tis)), and the mean...... of disease, vv(nuc), MI, and NI were of significant independent, prognostic value. On the basis of the multivariate analyses, a prognostic index with highly distinguishing capacity between prognostically poor and favorable cases was constructed. CONCLUSION: Quantitative histopathologic variables are of value...
Oscillation criteria for nonlinear fractional differential equation with damping term
Directory of Open Access Journals (Sweden)
Bayram Mustafa
2016-01-01
Full Text Available In this paper, we study the oscillation of solutions to a non-linear fractional differential equation with damping term. The fractional derivative is defined in the sense of the modified Riemann-Liouville derivative. By using a variable transformation, a generalized Riccati transformation, inequalities, and integration average techniquewe establish new oscillation criteria for the fractional differential equation. Several illustrative examples are also given.
Lie symmetry analysis of some time fractional partial differential equations
El Kinani, E. H.; Ouhadan, A.
2015-04-01
This paper uses Lie symmetry analysis to reduce the number of independent variables of time fractional partial differential equations. Then symmetry properties have been employed to construct some exact solutions.
The Fractional Ornstein-Uhlenbeck Process
DEFF Research Database (Denmark)
Høg, Esben; Frederiksen, Per H.
The paper revisits dynamic term structure models (DTSMs) and proposes a new way in dealing with the limitation of the classical affine models. In particular, this paper expands the flexibility of the DTSMs by applying a fractional Brownian motion as the governing force of the state variable inste...... of the bond is recovered by solving a fractional version of the fundamental bond pricing equation. Besides this theoretical contribution, the paper proposes an estimation methodology based on the Kalman filter approach, which is applied to the US term structure of interest rates....
Study of oil and residual fractions in products of thermal destruction of bitumen beds
Energy Technology Data Exchange (ETDEWEB)
Diskina, D.Ye.; Kadyrov, M.U.; Shabalina, T.N.; Soldatova, V.G.; Tokareva, R.V.; Tyshchenko, N.Ye.; Usacheva, G.M.; Vigdergauz, M.S.
1981-01-01
Investigation of average and heavy fractions derived from thermodestruction products in the bitumen bed at Mordovo-Karmal in Tatariya. Composition of average fractions is characterized by presence of unsaturated and a certain volume of oxygen-containing compounds, as well as high content of S and a low congelation temp. With respect to content of aromatic compounds, these fractions are similar to fractions of sulphurous oils. Residual fractions (..-->..350/sup 0/) were studied by conversion chromatography; these have low values of viscosity, density, content of S (in comparison with the same fractions of Mordovo-Karmal oil). Examines potential directions for utilizing these fractions.
Institute of Scientific and Technical Information of China (English)
井霞霞; 张德生; 张延利; 刘常明
2012-01-01
WTI spot price sequence was modelled and predicted based on fractional differencing and partially linear autoregression model. Firstly,we obtain a sbort memory sequence which is fractional differencing e-liminating long memory of the WTI spot price sequence, and then introduce a model in which the parameters part considers oil prices and the non-parameters aspect considers exogenous variables that is world oil supply,by using partially linear autoregression model for the short memory. The result of the empirical research show that the partially linear autoregression model based on fractional differencing can solve the oil price forecast better,and the introduction of exogenous variables,further enhance the model's explanatory ability,and make up the model of the external factors neglected defects. It has high accuracy of prediction.%利用分数差分和部分线性自回归模型对WTI现货价格序列进行了建模和预测研究.首先通过分数差分消除了WTI现货价格序列中的长记忆性,得到一条短记忆序列.然后,利用部分线性自回归模型对其进行建模,其中,参数部分考虑石油价格,非参数部分考虑外生变量,即世界供应量,并进行了实证研究.研究结果表明:基于分数差分的部分线性自回归模型能较好地解决石油价格预测这一问题,而引入外生变量后,进一步增强了模型的解释能力,弥补了模型对外界影响因素忽略的缺陷,预测精度较高.
From Complex Fractional Fourier Transform to Complex Fractional Radon Transform
Institute of Scientific and Technical Information of China (English)
FAN Hong-Yi; JIANG Nian-Quan
2004-01-01
We show that for n-dimensional complex fractional Fourier transform the corresponding complex fractional Radon transform can also be derived, however, it is different from the direct product of two n-dimensional real fractional Radon transforms. The complex fractional Radon transform of two-mode Wigner operator is calculated.
Hart, Kathleen; Kerslake, Daphne
The Concepts in Secondary Mathematics and Science (CSMS) and Strategies and Errors in Secondary Mathematics (SESM) research projects based at Chelsa College, England, have shown the marked reluctance of secondary school students to use fractions when solving mathematical problems, even though they have been taught the topic for a number of years.…
Brewing with fractionated barley
Donkelaar, van L.H.G.
2016-01-01
Brewing with fractionated barley Beer is a globally consumed beverage, which is produced from malted barley, water, hops and yeast. In recent years, the use of unmalted barley and exogenous enzymes have become more popular because they enable simpler processing and reduced environmental impact. Raw
Stephens, Ana C.; Bottge, Brian A.; Rueda, Enrique
2009-01-01
This article describes a technology-based and hands-on instructional intervention designed to advance middle school students' understandings of fractions. This problem-solving experience is based on the principles of Enhanced Anchored Instruction (EAI) and proved instructionally worthwhile and motivating to teachers and students in both inclusive …
Vinogradova, Natalya; Blaine, Larry
2013-01-01
Almost everyone loves chocolate. However, the same cannot be said about fractions, which are loved by markedly fewer. Middle school students tend to view them with wary respect, but little affection. The authors attempt to sweeten the subject by describing a type of game involving division of chocolate bars. The activity they describe provides a…
Fractional statistics and confinement
Gaete, P; Gaete, Patricio; Wotzasek, Clovis
2004-01-01
It is shown that a pointlike composite having charge and magnetic moment displays a confining potential for the static interaction while simultaneously obeying fractional statistics in a pure gauge theory in three dimensions, without a Chern-Simons term. This result is distinct from the Maxwell-Chern-Simons theory that shows a screening nature for the potential.
Brewing with fractionated barley
Donkelaar, van L.H.G.
2016-01-01
Brewing with fractionated barley Beer is a globally consumed beverage, which is produced from malted barley, water, hops and yeast. In recent years, the use of unmalted barley and exogenous enzymes have become more popular because they enable simpler processing and reduced environmental impact. Raw
Fractional Differential Equation
Directory of Open Access Journals (Sweden)
Moustafa El-Shahed
2007-01-01
where 2<α<3 is a real number and D0+α is the standard Riemann-Liouville fractional derivative. Our analysis relies on Krasnoselskiis fixed point theorem of cone preserving operators. An example is also given to illustrate the main results.
Effect of reinforcement volume fraction on the density & elastic ...
African Journals Online (AJOL)
صﺧﻟﻣ. ق. ﻲﻧدﻌﻣﻟا جﺎﺟزﻟا نﻣ سﮐﯾرﺗﺎﻣ وﻧ طﯾﻟﺧﻟﻟ ﺔﯾﻟوطﻟا ﺔﻧورﻣﻟا تﺑاوﺛ و ﺔﻓﺎﺛﮐﻟا ﯽﻟﻋ ﺔﯾوﻘﻣﻟا فﺎﯾﻟﻷا ﺔﺑﺳﻧ رﯾﻐﺗ رﯾﺛﺄﺗ ﺔﺳاردﺑ ﺎﻧﻣ. ) Zr41.2Ti13.8Cu12.5Ni10Be22.5. (. نﻣ فﺎﯾﻟﺄﺑ ﺔﻣﻋدﻣﻟا. : glass E. ,. Fe.
High Volume Fraction Carbon Nanotube Composites for Aerospace Applications
Siochi, Emilie J.; Kim, Jae-Woo; Sauti, Godfrey; Cano, Roberto J.; Wincheski, Russell A.; Ratcliffe, James G.; Czabaj, Michael; Jensen, Benjamin D.; Wise, Kristopher E.
2015-01-01
Reported nanoscale mechanical properties of carbon nanotubes (CNTs) suggest that their use may enable the fabrication of significantly lighter structures for use in space applications. To be useful in the fabrication of large structures, however, their attractive nanoscale properties must be retained as they are scaled up to bulk materials and converted into practically useful forms. Advances in CNT production have significantly increased the quantities available for use in manufacturing processes, but challenges remain with the retention of nanoscale properties in larger assemblies of CNTs. This work summarizes recent progress in producing carbon nanotube composites with tensile properties approaching those of carbon fiber reinforced polymer composites. These advances were achieved in nanocomposites with CNT content of 70% by weight. The processing methods explored to yield these CNT composite properties will be discussed, as will the characterization and test methods that were developed to provide insight into the factors that contribute to the enhanced tensile properties. Technology maturation was guided by parallel advancements in computational modeling tools that aided in the interpretation of experimental data.
High Volume Fraction Carbon Nanotube Composites for Aerospace Applications
Siochi, E. J.; Kim, J.-W.; Sauti, G.; Cano, R. J.; Wincheski, R. A.; Ratcliffe, J. G.; Czabaj, M.
2016-01-01
Reported mechanical properties of carbon nanotubes (CNTs) at the nanoscale suggest their potential to enable significantly lighter structures of interest for space applications. However, their utility depends on the retention of these properties in bulk material formats that permit practical fabrication of large structures. This presentation summarizes recent progress made to produce carbon nanotube composites with specific tensile properties that begin to rival those of carbon fiber reinforced polymer composites. CNT content in these nanocomposites was greater than 70% by weight. Tested nanocomposite specimens were fabricated from kilometers or tens of square meters of CNT, depending on the starting material format. Processing methods to yield these results, and characterization and testing to evaluate the performance of these composites will be discussed. The final objective is the demonstration of a CNT composite overwrapped pressure vessel to be flight tested in the Fall of 2016.
Schreurs, Liesbeth; Busz, D. M.; Paardekooper, G. M. R. M.; Beukema, J. C.; Jager, P. L.; Van der Jagt, E. J.; van Dam, G. M.; Groen, H.; Plukker, J. Th. M.; Langendijk, J. A.
2010-01-01
P>Target volume definition in modern radiotherapy is based on planning computed tomography (CT). So far, 18-fluorodeoxyglucose positron emission tomography (FDG-PET) has not been included in planning modality in volume definition of esophageal cancer. This study evaluates fusion of FDG-PET and CT in
A Computer-Interfaced Drop Counter as an Inexpensive Fraction Collector for Column Chromatography
Nash, Barbara T.
2008-01-01
A computer-interfaced drop counter is described that serves as an inexpensive alternative to a fraction collector for column chromatography experiments. Undergraduate biochemistry laboratories frequently do not have the budget to purchase fraction collectors. Protocols that call for the manual measurement of fraction volumes as well as the manual…
A Computer-Interfaced Drop Counter as an Inexpensive Fraction Collector for Column Chromatography
Nash, Barbara T.
2008-01-01
A computer-interfaced drop counter is described that serves as an inexpensive alternative to a fraction collector for column chromatography experiments. Undergraduate biochemistry laboratories frequently do not have the budget to purchase fraction collectors. Protocols that call for the manual measurement of fraction volumes as well as the manual…
Dependence of stability of metastable superconductors on copper fraction
Energy Technology Data Exchange (ETDEWEB)
Elrod, S. A.; Lue, J. W.; Miller, J. R.; Dresner, L.
1980-12-01
The stability of composite superconductors operating in the metastable regime depends upon such factors as matrix resistivity, cooled surface dimensions, fraction of critical current, and volume fraction of stabilizer. By assuming constant thermophysical properties, we developed analytic expressions for the energy and voltage of the minimum propagating zone (MPZ). With other factors held constant, these expressions have been used to predict composite superconductor stability as a function of copper fraction: lower copper fractions lead to higher MPZ energies. MPZ voltages have been measured for three NbTi/Cu composites having different copper fractions and different critical current densities for several magnetic fields and transport currents. Experimental MPZ voltages have been used to calculate an effective heat transfer coefficient, which is subsequently used to calculate the MPZ energy. The experimental MPZ energies support the theoretical expectation that lower copper fractions lead to higher stability in the metastable regime.
Directory of Open Access Journals (Sweden)
Eduardo Lima Garcia
2015-01-01
Full Text Available Abstract Background: Heart failure with preserved ejection fraction is a syndrome characterized by changes in diastolic function; it is more prevalent among the elderly, women, and individuals with systemic hypertension (SH and diabetes mellitus. However, in its early stages, there are no signs of congestion and it is identified in tests by adverse remodeling, decreased exercise capacity and diastolic dysfunction. Objective: To compare doppler, echocardiographic (Echo, and cardiopulmonary exercise test (CPET variables - ergospirometry variables - between two population samples: one of individuals in the early stage of this syndrome, and the other of healthy individuals. Methods: Twenty eight outpatients diagnosed with heart failure according to Framingham’s criteria, ejection fraction > 50% and diastolic dysfunction according to the european society of cardiology (ESC, and 24 healthy individuals underwent Echo and CPET. Results: The group of patients showed indexed atrial volume and left ventricular mass as well as E/E’ and ILAV/A´ ratios significantly higher, in addition to a significant reduction in peak oxygen consumption and increased VE/VCO2 slope, even having similar left ventricular sizes in comparison to those of the sample of healthy individuals. Conclusion: There are significant differences between the structural and functional variables analyzed by Echo and CPET when comparing two population samples: one of patients in the early stage of heart failure with ejection fraction greater than or equal to 50% and another of healthy individuals.
Creating, Naming, and Justifying Fractions
Siebert, Daniel; Gaskin, Nicole
2006-01-01
For students to develop meaningful conceptions of fractions and fraction operations, they need to think of fractions in terms other than as just whole-number combinations. In this article, we suggest two powerful images for thinking about fractions that move beyond whole-number reasoning. (Contains 5 figures.)
Lung and Heart Dose Variability During Radiation Therapy of Non-Small Cell Lung Cancer.
Jan, Nuzhat; Guy, Christopher; Reshko, Leonid B; Hugo, Geoffrey D; Weiss, Elisabeth
2017-07-01
To investigate the hypothesis that positional and anatomic variations during radiation therapy induce changes in lung and heart volumes and associated radiation doses. In this longitudinal investigation, variations in lung and heart volumes and standard dose parameters of mean lung dose, lung V20Gy, mean heart dose, and heart V40Gy were analyzed on weekly 4-dimensional CT scans of 15 lung cancer patients during conventionally fractionated radiochemotherapy. Tumor, individual lung lobes, and heart were delineated on the mid-ventilation phase of weekly 4-dimensional CT scans. Lung lobes and heart were also contoured on individual breathing phases of pre-, mid-, and end-of-treatment scans. Planning dose was transferred to consecutive scans via rigid registration. Volume and dose variations were assessed relative to the initial planning scan. Interfraction lung volume variability relative to week 0 was twice as large as tidal volume variability (8.0% ± 5.3% vs 4.0% ± 3.3%, P=.003). Interfraction lung volume variation ranged between 0.8% and 17.1% for individual patient means. Lower lung lobes had larger volume variability compared with upper lobes (13.5% ± 8.1% vs 7.0% ± 5.0%, Pheart volume variation was 7.2% (range, 3.4%-12.6%). Average mean heart dose variation was 1.2 Gy (range, 0.1-3.0 Gy) and average heart V40Gy variation 1.4% (range, 0%-4.2%). Anatomic and positional variations during radiation therapy induce changes in radiation doses to lung and heart. Repeated lung and heart dose assessment will provide a better estimate of the actual delivered dose and will improve prediction models for normal tissue toxicity, if assessed in larger cohorts. Copyright © 2017 Elsevier Inc. All rights reserved.
Fractional lattice charge transport
Flach, Sergej; Khomeriki, Ramaz
2017-01-01
We consider the dynamics of noninteracting quantum particles on a square lattice in the presence of a magnetic flux α and a dc electric field E oriented along the lattice diagonal. In general, the adiabatic dynamics will be characterized by Bloch oscillations in the electrical field direction and dispersive ballistic transport in the perpendicular direction. For rational values of α and a corresponding discrete set of values of E(α) vanishing gaps in the spectrum induce a fractionalization of the charge in the perpendicular direction - while left movers are still performing dispersive ballistic transport, the complementary fraction of right movers is propagating in a dispersionless relativistic manner in the opposite direction. Generalizations and the possible probing of the effect with atomic Bose-Einstein condensates and photonic networks are discussed. Zak phase of respective band associated with gap closing regime has been computed and it is found converging to π/2 value. PMID:28102302
Fractions in elementary education
Quinn, Frank
2013-01-01
This paper is one of a series in which elementary-education practice is analyzed by comparison with the history of mathematics, mathematical structure, modern practice, and (occasionally) cognitive neuroscience. The primary concerns are: Why do so many children find elementary mathematics difficult? And, why are the ones who succeed still so poorly prepared for college material needed for technical careers? The answer provided by conventional wisdom is essentially that mathematics is difficult. Third-graders are not developmentally ready for the subtlety of fractions, for instance, and even high-performing students cannot be expected to develop the skills of experienced users. However we will see that this is far from the whole story and is probably wrong: elementary-education fractions are genuinely harder and less effective than the version employed by experienced users. Experts discard at least 90% of what is taught in schools. Our educational system is actually counterproductive for skill development, and...