3,210 research outputs found
Uma nova proposta de indicadores de sustentabilidade na mineração
The mineral industry has commitments towards sustainability that are urgent and permanent. The sectorrepresents a rich field of analysis for the encounter of economic and environmental rationalities. Dueto the scale of activities and socio-environmental impacts, and their operation under heavy pressuresfrom the global commodities markets, it is important to understand the recent evolution of this sector. Inparallel, building sustainability indicators to monitor regions with large mines is a growing imperative.This article discusses various features of sustainable development and analyzes existing categories ofsustainability indicators for mining, based on recent literature. It also proposes sustainability indicatorsfor industrial mining, in the environmental, economic and social spheres, adaptable to tropical regions,including the Carajás Mineral Province, southeast of Pará State (Amazon, Brazil).A indústria mineral tem compromissos permanentes e inadiáveis com a sustentabilidade. O setor representa um rico campo de análise sobre o encontro entre as racionalidades econômica e ambiental. Justamente pela magnitude das escalas em que as mineradoras atuam e de seus impactos socioambientais, e por operarem sob pesadas pressões que incidem no mercado global de commodities, importa compreender essa evolução recente no setor. Em paralelo, é imperativo construir indicadores para monitorar a sustentabilidade em regiões que abrigam grandes minas. Este artigo discute os diversos aspectos do desenvolvimento sustentável e analisa as categorias propostas de indicadores de sustentabilidade na mineração, com base em literatura recente. A partir daí, propõe um conjunto de indicadores de sustentabilidade para a mineração industrial, nos eixos ambiental, econômico e social, com aderência a regiões tropicais, entre as quais a Província Mineral de Carajás, localizada na região sudeste do estado do Pará (Amazônia, Brasil)
Direct block scheduling technology : analysis of avidity.
This study is focused on Direct Block Scheduling testing (Direct Multi-Period
Scheduling methodology) which schedules mine production considering the correct
discount factor of each mining block, resulting in the final pit. Each block is analyzed
individually in order to define the best target period. This methodology presents an
improvement of the classical methodology derived from Lerchs-Grossmann?s initial
proposition improved by Whittle. This paper presents the differences between these
methodologies, specially focused on the algorithms? avidity. Avidity is classically defined
by the voracious search algorithms, whereupon some of the most famous greedy
algorithms are Branch and Bound, Brutal Force and Randomized. Strategies based on
heuristics can accentuate the voracity of the optimizer system. The applied algorithm
use simulated annealing combined with Tabu Search. The most avid algorithm can
select the most profitable blocks in early periods, leading to higher present value in the
first periods of mine operation. The application of discount factors to blocks on the
Lerchs-Grossmann?s final pit has an accentuated effect with time, and this effect may
make blocks scheduled for the end of the mine life unfeasible, representing a trend to
a decrease in reported reserves
Observation of two new baryon resonances
Two structures are observed close to the kinematic threshold in the mass spectrum in a sample of proton-proton collision data, corresponding
to an integrated luminosity of 3.0 fb recorded by the LHCb experiment.
In the quark model, two baryonic resonances with quark content are
expected in this mass region: the spin-parity and
states, denoted and .
Interpreting the structures as these resonances, we measure the mass
differences and the width of the heavier state to be
MeV,
MeV,
MeV, where the first and second
uncertainties are statistical and systematic, respectively. The width of the
lighter state is consistent with zero, and we place an upper limit of
MeV at 95% confidence level. Relative
production rates of these states are also reported.Comment: 17 pages, 2 figure
Observation of associated production of a boson with a meson in the~forward region
A search for associated production of a boson with an open charm meson is
presented using a data sample, corresponding to an integrated luminosity of
of proton--proton collisions at a centre-of-mass energy
of 7\,TeV, collected by the LHCb experiment. %% Seven candidate events for
associated production of a boson with a meson and four candidate
events for a boson with a meson are observed with a combined
significance of 5.1standard deviations. The production cross-sections in the
forward region are measured to be where the first uncertainty is statistical and the
second systematic.Comment: 18 pages, 2 figure
Measurements of the , , meson and baryon lifetimes
Measurements of -hadron lifetimes are reported using collision data,
corresponding to an integrated luminosity of 1.0fb, collected by the
LHCb detector at a centre-of-mass energy of Tev. Using the exclusive decays
, , ,
and the average decay
times in these modes are measured to be = 0.004 0.003 ps, =
0.006 0.004 ps, = 0.013
0.005 ps, = 0.027
0.006 ps and = 0.011
0.005 ps, where the first uncertainty is statistical and the second is
systematic. These represent the most precise lifetime measurements in these
decay modes. In addition, ratios of these lifetimes, and the ratio of the
decay-width difference, , to the average width, , in
the system, , are
reported. All quantities are found to be consistent with Standard Model
expectations.Comment: 28 pages, 4 figures. Updated reference
Bose-Einstein correlations of same-sign charged pions in the forward region in pp collisions at √s=7 TeV
Bose-Einstein correlations of same-sign charged pions, produced in protonproton collisions at a 7 TeV centre-of-mass energy, are studied using a data sample collected
by the LHCb experiment. The signature for Bose-Einstein correlations is observed in the
form of an enhancement of pairs of like-sign charged pions with small four-momentum
difference squared. The charged-particle multiplicity dependence of the Bose-Einstein correlation parameters describing the correlation strength and the size of the emitting source
is investigated, determining both the correlation radius and the chaoticity parameter. The
measured correlation radius is found to increase as a function of increasing charged-particle
multiplicity, while the chaoticity parameter is seen to decreas
Study of and decays and determination of the CKM angle
We report a study of the suppressed and favored
decays, where the neutral meson is detected
through its decays to the and CP-even and
final states. The measurement is carried out using a proton-proton
collision data sample collected by the LHCb experiment, corresponding to an
integrated luminosity of 3.0~fb. We observe the first significant
signals in the CP-even final states of the meson for both the suppressed
and favored modes, as well as
in the doubly Cabibbo-suppressed final state of the decay. Evidence for the ADS suppressed decay , with , is also presented. From the observed
yields in the , and their
charge conjugate decay modes, we measure the value of the weak phase to be
. This is one of the most precise
single-measurement determinations of to date.Comment: 22 pages, 9 figures; All figures and tables, along with any
supplementary material and additional information, are available at
https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2015-020.htm
Observation of an Excited Bc+ State
Using pp collision data corresponding to an integrated luminosity of 8.5 fb-1 recorded by the LHCb experiment at center-of-mass energies of s=7, 8, and 13 TeV, the observation of an excited Bc+ state in the Bc+π+π- invariant-mass spectrum is reported. The observed peak has a mass of 6841.2±0.6(stat)±0.1(syst)±0.8(Bc+) MeV/c2, where the last uncertainty is due to the limited knowledge of the Bc+ mass. It is consistent with expectations of the Bc∗(2S31)+ state reconstructed without the low-energy photon from the Bc∗(1S31)+→Bc+γ decay following Bc∗(2S31)+→Bc∗(1S31)+π+π-. A second state is seen with a global (local) statistical significance of 2.2σ (3.2σ) and a mass of 6872.1±1.3(stat)±0.1(syst)±0.8(Bc+) MeV/c2, and is consistent with the Bc(2S10)+ state. These mass measurements are the most precise to date
Quantum numbers of the state and orbital angular momentum in its decay
Angular correlations in decays, with , and , are used to measure
orbital angular momentum contributions and to determine the value of
the meson. The data correspond to an integrated luminosity of 3.0
fb of proton-proton collisions collected with the LHCb detector. This
determination, for the first time performed without assuming a value for the
orbital angular momentum, confirms the quantum numbers to be .
The is found to decay predominantly through S wave and an upper limit
of at C.L. is set on the fraction of D wave.Comment: 16 pages, 4 figure
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