2,120 research outputs found
Microscopic Description of Deeply Virtual Compton Scattering off Spin-0 Nuclei
We evaluate within a microscopic calculation the contributions of both
coherent and incoherent deeply virtual Compton scattering from a spin-0
nucleus. The coherent contribution is obtained when the target nucleus recoils
as a whole, whereas for incoherent scattering break-up configurations for the
final nucleus into a an outgoing nucleon and an system are considered.
The two processes encode different characteristics of generalized parton
distributions.Comment: 7 pages, 3 figure
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Distributed Resources Shift Paradigms on Power System Design, Planning, and Operation: An Application of the GAP Model
Power systems have evolved following a century-old paradigm of planning and operating a grid based on large central generation plants connected to load centers through a transmission grid and distribution lines with radial flows. This paradigm is being challenged by the development and diffusion of modular generation and storage technologies. We use a novel approach to assess the sequencing and pacing of centralized, distributed, and off-grid electrification strategies by developing and employing the grid and access planning (GAP) model. GAP is a capacity expansion model to jointly assess operation and investment in utility-scale generation, transmission, distribution, and demand-side resources. This paper conceptually studies the investment and operation decisions for a power system with and without distributed resources. Contrary to the current practice, we find hybrid systems that pair grid connections with distributed energy resources (DERs) are the preferred mode of electricity supply for greenfield expansion under conservative reductions in photovoltaic panel (PV) and energy storage prices. We also find that when distributed PV and storage are employed in power system expansion, there are savings of 15%-20% mostly in capital deferment and reduced diesel use. Results show that enhanced financing mechanisms for DER PV and storage could enable 50%-60% of additional deployment and save 15 /MWh in system costs. These results have important implications to reform current utility business models in developed power systems and to guide the development of electrification strategies in underdeveloped grids
Nuclear Medium Modifications of Hadrons from Generalized Parton Distributions
We study the structure of generalized parton distributions in spin 0 nuclei
within a microscopic approach for nuclear dynamics. GPDs can be used on one
side as tools to unravel the deep inelastic transverse structure of nuclei in
terms of both transverse spatial and transverse momentum degrees of freedom. On
the other, one can obtain information on GPDs themselves by observing how they
become modified in the nuclear environment. We derive the structure of the
nuclear deeply virtual Compton scattering tensor and generalized parton
distributions at leading order in in a field-theoretical framework. The
nuclear generalized parton distributions are calculated using a two step
process -- the convolution approach -- where the scattering process happens
from a quark inside a nucleon, itself inside a nucleus, disregarding final
state interactions with both the nuclear and nucleon debris. We point out that
details of the nuclear long range interactions such as two-body currents, can
be disregarded compared to the deep inelastic induced modifications of the
bound GPDs. We show how the pattern of nuclear modifications predicted, and in
particular the deviations of off-shell effects from the longitudinal
convolution provide clear signals to be sought in experimental measurements.
Finally, we find interesting relationships by studying Mellin moments in
nuclei: in particular we predict the -dependence for the -term of GPDs
within a microscopic approach, and the behavior with of the total momentum
carried by quarks in a nucleus. The latter provides an important element for
the evaluation of nuclear hadronization phenomena which are vital for
interpreting current and future data at RHIC, HERMES and Jefferson Lab.Comment: 29 pages, 10 figure
An Evaluation of Multiple Perceptions of Digital Rights Management
Digital Rights Management (DRM) solutions have generated much interest because of their influence on the expectations and responsibilities of customers and related organizations. It was created to restrict piracy and enhance digital media sales, however, it is found to be unable to fulfill its objectives. We find the protections by DRM lack an understanding of the end user and the evolving nature of copyright and fair use. The potential motives for pirating appear to increase as DRM becomes more intrusive causing a conflict in the objectives of DRM. Thus, adjustments must be made to the current DRM model in order for it to become beneficial for both the producer and the consumer. Our research identifies the needs, desires, and responsibilities of the various DRM stakeholders so that a successful use of DRM technologies can be modeled: a challenge faced by the media industry
Generalized Parton Distributions from Hadronic Observables: Zero Skewness
We propose a physically motivated parametrization for the unpolarized
generalized parton distributions. At zero value of the skewness variable,
, the parametrization is constrained by simultaneously fitting the
experimental data on both the nucleon elastic form factors and the deep
inelastic structure functions. A rich phenomenology can be addressed based on
this parametrization. In particular, we track the behavior of the average: {\it
i)} interparton distances as a function of the momentum fraction, , {\it
ii)} as a function of the four-momentum transfer, ; and {\it iii)} the
intrinsic transverse momentum as a function of . We discuss the
extension of our parametrization to where additional constraints
are provided by higher moments of the generalized parton distributions obtained
from {\it ab initio} lattice QCD calculations.Comment: 42 pages, 21 figure
Mass and Number and Its Chemical Composition Distribution of Particulate Matter in Different Microenvironments
Adverse health effects from exposure to air pollution are a global challenge and of widespread concern. Therefore, the present study attempted to pave the way in the study of indoor air pollution by coarse and fine particulate matter and picturesque its relation with the different indoor microenvironment. A campaign study was conducted in the city of Taj âAgra,â India in which different microenvironments were selected (i.e., offices, shops, and commercial centers). For each site, two different locations were chosen to examine the coarse particles (PM10 and PM5.0) and fine particles (PM2.5, PM1.0, PM0.5 and PM0.25) concentrations and metal concentration of Zn, Pb, Ni, Fe, Cr, Cd, Mg and Cu in PM2.5 and for their related health effects. The exposure factor and health risk assessment for carcinogenic effects due to heavy metal contaminants have also been calculated for adults working in different microenvironment by following the methodology prescribed by US EPA
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