579 research outputs found
Monotonicity of quantum ground state energies: Bosonic atoms and stars
The N-dependence of the non-relativistic bosonic ground state energy is
studied for quantum N-body systems with either Coulomb or Newton interactions.
The Coulomb systems are "bosonic atoms," with their nucleus fixed, and the
Newton systems are "bosonic stars". In either case there exists some third
order polynomial in N such that the ratio of the ground state energy to the
respective polynomial grows monotonically in N. Some applications of these new
monotonicity results are discussed
Synthesis of Bio-Dimethyl Ether Based on Carbon Dioxide-Enhanced Gasification of Biomass: Process Simulation Using Aspen Plus
YesProcess simulation of a single-step synthesis of DME based on CO2-enhanced gasification of rice straw was conducted using Aspen PlusTM. The process consists of gasification unit, heat recovery unit, gas purification unit, single-step DME synthesis, and DME separation unit. In the simulation, highly pure DME was produced by the control of CO2 concentration in syngas to a very low level prior to synthesis. A gasification system efficiency of 36.7% and CO2 emission of 1.31 kg/kg of DME were achieved. Bio-DME production based on CO2-enhanced gasification of biomass was found to be more cost-effective as it required 19.6% less biomass than that of DME production based on conventional biomass gasification. The performance and environmental benefits of the proposed process could be further improved by the utilization of unreacted gases and the handling of CO2 generated via incorporating poly-generation concept or carbon storage, which could also potentially improve process economics.Ningbo Bureau of Science and Technology; Innovation Team Scheme; Major R&D Programme; Provincial Innovation Team on the Commercialisation of SOx and NOx Removal Technologies; University of Nottingham Ningbo Chin
Extended quantum conditional entropy and quantum uncertainty inequalities
Quantum states can be subjected to classical measurements, whose
incompatibility, or uncertainty, can be quantified by a comparison of certain
entropies. There is a long history of such entropy inequalities between
position and momentum. Recently these inequalities have been generalized to the
tensor product of several Hilbert spaces and we show here how their derivations
can be shortened to a few lines and how they can be generalized. All the
recently derived uncertainty relations utilize the strong subadditivity (SSA)
theorem; our contribution relies on directly utilizing the proof technique of
the original derivation of SSA.Comment: 4 page
Information capacity of quantum observable
In this paper we consider the classical capacities of quantum-classical
channels corresponding to measurement of observables. Special attention is paid
to the case of continuous observables. We give the formulas for unassisted and
entanglement-assisted classical capacities and consider some
explicitly solvable cases which give simple examples of entanglement-breaking
channels with We also elaborate on the ensemble-observable duality
to show that for the measurement channel is related to the
-quantity for the dual ensemble in the same way as is related to the
accessible information. This provides both accessible information and the
-quantity for the quantum ensembles dual to our examples.Comment: 13 pages. New section and references are added concerning the
ensemble-observable dualit
Clustering Nominal and Numerical Data: A New Distance Concept for a Hybrid Genetic Algorithm
As intrinsic structures, like the number of clusters, is, for real data, a major issue of the clustering problem, we propose, in this paper, CHyGA (Clustering Hybrid Genetic Algorithm) an hybrid genetic algorithm for clustering. CHyGA treats the clustering problem as an optimization problem and searches for an optimal number of clusters characterized by an optimal distribution of instances into the clusters. CHyGA introduces a new representation of solutions and uses dedicated operators, such as one iteration of K-means as a mutation operator. In order to deal with nominal data, we propose a new definition of the cluster center concept and demonstrate its properties. Experimental results on classical benchmarks are given
Personal identity (de)formation among lifestyle travellers: A double-edged sword?
This article explores the personal identity work of lifestyle travellers – individuals for whom extended leisure travel is a preferred lifestyle that they return to repeatedly. Qualitative findings from in-depth semi-structured interviews with lifestyle travellers in northern India and southern Thailand are interpreted in light of theories on identity formation in late modernity that position identity as problematic. It is suggested that extended leisure travel can provide exposure to varied cultural praxes that may contribute to a sense of social saturation. Whilst a minority of the respondents embraced a saturation of personal identity in the subjective formation of a cosmopolitan cultural identity, several of the respondents were paradoxically left with more identity questions than answers as the result of their travels
Monitoring permanent CO2 storage by in situ mineral carbonation using a reactive tracer technique
AbstractIn situ mineral carbonation provides the most effective and permanent solution for geologic CO2 storage. Basaltic rocks have the potential to store large volumes of CO2 as (Ca, Mg, Fe) carbonates [1]. Existing monitoring and verification techniques for geologic CO2 storage are insufficient to quantitatively characterize solubility and mineral trapping in a geologic reservoir. We developed and tested a new reactive tracer technique for quantitative monitoring and detection of dissolved and chemically transformed CO2. The technique involves the active tagging of the injected CO2 with low levels of radiocarbon (14C) as a reactive tracer in combination with the injection of non-reactive tracers such as sulfurhexafluoride (SF6) and trifluoromethylsulphur pentafluoride (SF5CF3). The tracer technique has been applied at the CarbFix pilot injection site in Hellisheidi, Iceland as part of a comprehensive geochemical monitoring program during two injection phases; Phase III and IV. SF6 and SF5CF3 confirm the arrival of the injected CO2 and CO2+H2S solutions at the first observation well HN04, which is 125m west of the injection well at 520 m depth. The initial breakthrough of the migrating dissolved CO2 front occurred 63 and 62 days after injection began as evidenced by an initial peak in the SF6, SF5CF3, 14C, and dissolved inorganic carbon (DIC) concentrations. The major increase in the non-reactive tracer concentrations occurred several months after the initial breakthrough, although no major concentration increase has been observed for 14C and DIC suggesting that mineral reactions are dominant during CO2 injection
Weakly-Bound Three-Body Systems with No Bound Subsystems
We investigate the domain of coupling constants which achieve binding for a
3-body system, while none of the 2-body subsystems is bound. We derive some
general properties of the shape of the domain, and rigorous upper bounds on its
size, using a Hall--Post decomposition of the Hamiltonian. Numerical
illustrations are provided in the case of a Yukawa potential, using a simple
variational method.Comment: gzipped ps with 11 figures included. To appear in Phys. Rev.
Minimal Composite Higgs Model with Light Bosons
We analyze a composite Higgs model with the minimal content that allows a
light Standard-Model-like Higgs boson, potentially just above the current LEP
limit. The Higgs boson is a bound state made up of the top quark and a heavy
vector-like quark. The model predicts that only one other bound state may be
lighter than the electroweak scale, namely a CP-odd neutral scalar. Several
other composite scalars are expected to have masses in the TeV range. If the
Higgs decay into a pair of CP-odd scalars is kinematically open, then this
decay mode is dominant, with important implications for Higgs searches. The
lower bound on the CP-odd scalar mass is loose, in some cases as low as
100 MeV, being set only by astrophysical constraints.Comment: 33 pages, latex. Corrections in eqs. 3.21, 3.23, 4.1, 4.5-10. One
figure adde
- …