1,768 research outputs found
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Examining the economic impact of transport complex economies
Transport complex economies (TCEs), which comprise both upstream and downstream firms in the transport chain that conduct shipping and trade-related activities, can be desirable locations for port users (e.g., traders, logistics service providers, shipping lines and terminal operators) to perform their business activities. To explore TCEs, this study identifies trade facilitation measures at both the macro and micro levels to enhance regional performance. Hypotheses have been developed to build a theoretical model to illustrate the relationship between trade facilitation activities and trade costs. The economic outcomes are also examined in the theoretical model. To validate the proposed model, we have collected data from the World Bank and employed structural equation modelling. The result suggests that trade facilitation measures are negatively associated with trade cost. The result also suggests that the trade facilitation measures of a region is positively associated with its economic performance. Based on the findings, users can formulate effective and efficient strategies to select a location for their firm to conduct business activities. The findings illustrate the importance of the development of social capital for trade facilitation from the perspective of policy makers
Human African trypanosomiasis : the current situation in endemic regions and the risks for non-endemic regions from imported cases
Human African trypanosomiasis (HAT) is caused by Trypanosoma brucei
gambiense and T. b. rhodesiense and caused devastating epidemics during the 20th
century. Due to effective control programs implemented in the last two decades, the
number of reported cases has fallen to a historically low level. Although fewer than
977 cases were reported in 2018 in endemic countries, HAT is still a public health
problem in endemic regions until it is completely eliminated. In addition, almost 150
confirmed HAT cases were reported in non-endemic countries in the last three
decades. The majority of non-endemic HAT cases were reported in Europe, United
States and South Africa, due to historical alliances, economic links or geographic
proximity to disease endemic countries. Furthermore, with the implementation of the
“Belt and Road” project, sporadic imported HAT cases have been reported in China
as a warning sign of tropical diseases prevention. In this paper, we explore and
interpret the data on HAT incidence and find no positive correlation between the
number of HAT cases from endemic and non-endemic countries.This data will
provide useful information for better understanding the imported cases of HAT
globally in the post-elimination phase
Continuum modelling of granular particle flow with inelastic inter-particle collisions
The kinetic theory of granular flow is a successful model for gas-solid flows. However, inelastic collisions between particles, among other mechanisms, cause agglomeration of particles, which may be the reason why undue sensitivity of the model to any slight inelasticity in inter-particle collisions has been seen previously. In contrast to a dry (i.e. no interstitial gas) granular system, this tendency to agglomerate in a gas driven two-phase system may be countered by the carrier gas turbulence. In this paper, a heuristic model for particle gas turbulence interaction is introduced within the scope of a generalized kinetic theory model which incorporates the carrier fluid effect on particulate stresses. The numerical results for the flow of granular particles in vertical pipes, which considers slightly inelastic inter-particle collisions, are in reasonably good agreement with published experimental data. Even in this relatively simple model, the results indicate that the interactions between the particle phase and gas turbulence need to be appropriately addressed in any kinetic theory based model for gas solid flows
Linear quadratic regulation of polytopic time-inhomogeneous Markov jump linear systems (extended version)
In most real cases transition probabilities between operational modes of
Markov jump linear systems cannot be computed exactly and are time-varying. We
take into account this aspect by considering Markov jump linear systems where
the underlying Markov chain is polytopic and time-inhomogeneous, i.e. its
transition probability matrix is varying over time, with variations that are
arbitrary within a polytopic set of stochastic matrices. We address and solve
for this class of systems the infinite-horizon optimal control problem. In
particular, we show that the optimal controller can be obtained from a set of
coupled algebraic Riccati equations, and that for mean square stabilizable
systems the optimal finite-horizon cost corresponding to the solution to a
parsimonious set of coupled difference Riccati equations converges
exponentially fast to the optimal infinite-horizon cost related to the set of
coupled algebraic Riccati equations. All the presented concepts are illustrated
on a numerical example showing the efficiency of the provided solution.Comment: Extended version of the paper accepted for the presentation at the
European Control Conference (ECC 2019
The Granular Phase Diagram
The kinetic energy distribution function satisfying the Boltzmann equation is
studied analytically and numerically for a system of inelastic hard spheres in
the case of binary collisions. Analytically, this function is shown to have a
similarity form in the simple cases of uniform or steady-state flows. This
determines the region of validity of hydrodynamic description. The latter is
used to construct the phase diagram of granular systems, and discriminate
between clustering instability and inelastic collapse. The molecular dynamics
results support analytical results, but also exhibit a novel fluctuational
breakdown of mean-field descriptions.Comment: 15 pages, 4 figure
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Design Principles for High-Capacity Mn-Based Cation-Disordered Rocksalt Cathodes
Mn-based Li-excess cation-disordered rocksalt (DRX) oxyfluorides are promising candidates for next-generation rechargeable battery cathodes owing to their large energy densities, the earth abundance, and low cost of Mn. In this work, we synthesized and electrochemically tested four representative compositions in the Li-Mn-O-F DRX chemical space with various Li and F content. While all compositions achieve higher than 200 mAh g−1 initial capacity and good cyclability, we show that the Li-site distribution plays a more important role than the metal-redox capacity in determining the initial capacity, whereas the metal-redox capacity is more closely related to the cyclability of the materials. We apply these insights and generate a capacity map of the Li-Mn-O-F chemical space, LixMn2-xO2-yFy (1.167 ≤ x ≤ 1.333, 0 ≤ y ≤ 0.667), which predicts both accessible Li capacity and Mn-redox capacity. This map allows the design of compounds that balance high capacity with good cyclability
Optimized acquisition time and image sampling for dynamic SPECT of Tl-201
Author name used in this publication: Dagan FengAuthor name used in this publication: Pak-Kong LunVersion of RecordPublishe
Fragmented and Single Condensate Ground States of Spin-1 Bose Gas
We show that the ground state of a spin-1 Bose gas with an antiferro-
magnetic interaction is a fragmented condensate in uniform magnetic fields. The
number fluctuations in each spin component change rapidly from being enormous
(order ) to exceedingly small (order 1) as the magnetization of the system
increases. A fragmented condensate can be turned into a single condensate state
by magnetic field gradients. The conditions for existence and the method of
detecting fragmented states are presented.Comment: 4 pages, no figure
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