147 research outputs found
Characterization of woodstove briquettes from torrefied biomass and coal
peer-reviewedUsing waste biomass materials offers the potential to reduce the greenhouse gas emissions from fossil fuels. Torrefaction is very useful for improving the fuel properties of biomass in order to better match those of coal. The aim of this work is to compare the properties of torrefied low quality biomass briquettes against coal equivalents. The composition of the briquettes was characterized by 13C CP/MAS, proximate analysis, and X-ray diffraction and the results were compared with equilibrium calculations. In addition to these techniques, we report for the first time on the use of XμCT for characterizing such materials. The XμCT analysis showed that the briquette structure contains carbon, binder and inorganic matter, with quartz retained from the original feedstock in torrefied biomass and coal briquettes. The CO2 reactivity of pulverized briquettes was investigated by thermogravimetric analysis. Results showed that the inorganic matter influences the reactivity less than the organic composition and porosity. Importantly from a technological standpoint, the increase in binder concentration and replacement of starch with resin binder did not influence the reactivity and calorific value of a pulverized briquette
Exclusive processes in position space and the pion distribution amplitude
We suggest to carry out lattice calculations of current correlators in
position space, sandwiched between the vacuum and a hadron state (e.g. pion),
in order to access hadronic light-cone distribution amplitudes (DAs). In this
way the renormalization problem for composite lattice operators is avoided
altogether, and the connection to the DA is done using perturbation theory in
the continuum. As an example, the correlation function of two electromagnetic
currents is calculated to the next-to-next-to-leading order accuracy in
perturbation theory and including the twist-4 corrections. We argue that this
strategy is fully competitive with direct lattice measurements of the moments
of the DA, defined as matrix elements of local operators, and offers new
insight in the space-time picture of hard exclusive reactions.Comment: 15 pages, 10 figure
A river model of space
Within the theory of general relativity gravitational phenomena are usually
attributed to the curvature of four-dimensional spacetime. In this context we
are often confronted with the question of how the concept of ordinary physical
three-dimensional space fits into this picture. In this work we present a
simple and intuitive model of space for both the Schwarzschild spacetime and
the de Sitter spacetime in which physical space is defined as a specified set
of freely moving reference particles. Using a combination of orthonormal basis
fields and the usual formalism in a coordinate basis we calculate the physical
velocity field of these reference particles. Thus we obtain a vivid description
of space in which space behaves like a river flowing radially toward the
singularity in the Schwarzschild spacetime and radially toward infinity in the
de Sitter spacetime. We also consider the effect of the river of space upon
light rays and material particles and show that the river model of space
provides an intuitive explanation for the behavior of light and particles at
and beyond the event horizons associated with these spacetimes.Comment: 22 pages, 5 figure
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Frequency dependence of magnetothermal properties for magnetic fluid and magnetically functionalized implants
Heating of the magnetic nanoparticles in AC magnetic field is the effect promising for application in medicine. The mechanisms of heating in AC-magnetic field implies nontrivial dependence of the power dissipated by magnetic nanoparticles on frequency. With the use of a reconfigurable experimental setup, this frequency-dependent magnetic heating was measured on two characteristic examples: the magnetite nanoparticles conventionally used in medicine and polymer coating with micrometer sized magnetite particles. The saturation of the heating power with frequency is shown that is more pronounced for the second case of microparticles
Sum rules and dualities for generalized parton distributions: is there a holographic principle?
To leading order approximation, the physical content of generalized parton
distributions (GPDs) that is accessible in deep virtual electroproduction of
photons or mesons is contained in their value on the cross-over trajectory.
This trajectory separates the t-channel and s-channel dominated GPD regions.
The underlying Lorentz covariance implies correspondence between these two
regions through their relation to GPDs on the cross-over trajectory. This point
of view leads to a family of GPD sum rules which are a quark analogue of finite
energy sum rules and it guides us to a new phenomenological GPD concept. As an
example, we discuss the constraints from the JLab/Hall A data on the dominant
u-quark GPD H. The question arises whether GPDs are governed by some kind of
holographic principle.Comment: 45 pages, 4 figures, Sect. 2 reorganized for clarity. Typos in Eq.
(20) corrected. 4 new refs. Matches published versio
Gravity and Electromagnetism with -type Coupling and Magnetic Monopole Solutions
We investigate -type coupling of electromagnetic fields to
gravity. After we derive field equations by a first order variational principle
from the Lagrangian formulation of the non-minimally coupled theory, we look
for static, spherically symmetric, magnetic monopole solutions. We point out
that the solutions can provide possible geometries which may explain the
flatness of the observed rotation curves of galaxies.Comment: 10 page
The Challenges of Creativity in Software Organizations
Part 1: Creating ValueInternational audienceManaging creativity has proven to be one of the most important drivers in software development and use. The continuous changing market environment drives companies like Google, SAS Institute and LEGO to focus on creativity as an increasing necessity when competing through sustained innovations. However, creativity in the information systems (IS) environment is a challenge for most organizations that is primarily caused by not knowing how to strategize creative processes in relation to IS strategies, thus, causing companies to act ad hoc in their creative endeavors. In this paper, we address the organizational challenges of creativity in software organizations. Grounded in a previous literature review and a rigorous selection process, we identify and present a model of seven important factors for creativity in software organizations. From these factors, we identify 21 challenges that software organizations experience when embarking on creative endeavors and transfer them into a comprehensive framework. Using an interpretive research study, we further study the framework by analyzing how the challenges are integrated in 27 software organizations. Practitioners can use this study to gain a deeper understanding of creativity in their own business while researchers can use the framework to gain insight while conducting interpretive field studies of managing creativity
Measurement of the Bottom-Strange Meson Mixing Phase in the Full CDF Data Set
We report a measurement of the bottom-strange meson mixing phase \beta_s
using the time evolution of B0_s -> J/\psi (->\mu+\mu-) \phi (-> K+ K-) decays
in which the quark-flavor content of the bottom-strange meson is identified at
production. This measurement uses the full data set of proton-antiproton
collisions at sqrt(s)= 1.96 TeV collected by the Collider Detector experiment
at the Fermilab Tevatron, corresponding to 9.6 fb-1 of integrated luminosity.
We report confidence regions in the two-dimensional space of \beta_s and the
B0_s decay-width difference \Delta\Gamma_s, and measure \beta_s in [-\pi/2,
-1.51] U [-0.06, 0.30] U [1.26, \pi/2] at the 68% confidence level, in
agreement with the standard model expectation. Assuming the standard model
value of \beta_s, we also determine \Delta\Gamma_s = 0.068 +- 0.026 (stat) +-
0.009 (syst) ps-1 and the mean B0_s lifetime, \tau_s = 1.528 +- 0.019 (stat) +-
0.009 (syst) ps, which are consistent and competitive with determinations by
other experiments.Comment: 8 pages, 2 figures, Phys. Rev. Lett 109, 171802 (2012
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