361 research outputs found
Finite-width Gaussian sum rules for pseudoscalar glueball based on correction from instanton-gluon interference to correlation function
Based on correction from instanton-gluon interference to correlation
function, the properties of the pseudoscalar glueball is investigated
in a family of finite-width Gaussian sum rules. In the framework of
semiclassical expansion for quantum chromodynamics in the
instanton liquid background, the contribution arising from the the interference
between instantons and the quantum gluon fields is calculated, and included in
the correlation function together with pure-classical contribution from
instantons and the perturbative one. The interference contribution is turned to
be gauge-invariant, free of infrared divergence, and has a great role to
restore the positivity of the spectra of the full correlation function. The
negligible contribution from vacuum condensates is excluded in our correlation
function to avoid the double counting. Instead of the usual zero-width
approximation for the resonances, the usual Breit-Wigner form with a suitable
threshold behavior for the spectral function of the finite-width resonances is
adopted. A consistency between the subtracted and unsubtracted sum rules is
very well justified. The values of the mass, decay width and coupling constants
for the resonance in which the glueball fraction is dominant are
obtained, and agree with the phenomenological analysis.Comment: 18 pages, 10 figure
Systematics of fusion probability in "hot" fusion reactions
The fusion probability in "hot" fusion reactions leading to the synthesis of
super-heavy nuclei is investigated systematically. The quasi-fission barrier
influences the formation of the super-heavy nucleus around the "island of
stability" in addition to the shell correction. Based on the quasi-fission
barrier height obtained with the Skyrme energy-density functional, we propose
an analytical expression for the description of the fusion probability, with
which the measured evaporation residual cross sections can be reproduced
acceptably well. Simultaneously, some special fusion reactions for synthesizing
new elements 119 and 120 are studied. The predicted evaporation residual cross
sections for 50Ti+249Bk are about 10-150fb at energies around the
entrance-channel Coulomb barrier. For the fusion reactions synthesizing element
120 with projectiles 54Cr and 58Fe, the cross sections fall to a few femtobarns
which seems beyond the limit of the available facilities.Comment: 5 figures, 1 tabl
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Review on stationary CPT technologies and coil designs for EVs
In the recent decade, the driving range of pure EVs with zero emission target has become a popular topic as the massive battery requirement for longer distance travels means higher vehicle cost and longer time of recharging periods. Stationary CPT charging solutions could be an alternative to reduce EVs weight, size and energy storage unit costs. Fortunately, with progressive success of low-power CPT charging applications proposed to be commercially produced in the past decade, hundreds of kilowatts level high-power CPT charging techniques for EVs are more and more expected to be an optimally suitable solution for recharging EV batteries, providing higher propulsion and delivering continuously longer driving range in the next generations of the EVs. The idea of deploying inductive coupling for EVs has acquired a lot of attentions in the last decade due to the contributions and advancements of power electronics, switching power supply, semiconductors, microprocessors, electrochemistry, material sciences, control technologies, electromagnetics and so on, despite many challenges to be addressed including EV manufacturing integration with CPT system under the chassis, infrastructure difficulties, system maintenance on both vehicle and transmitting ground sides, actual CPT performance with real-time coupling on real-world road. In order to ensure the realization and enhance the sustainability in transportation sector with the emerging CPT ideas, currently the stationary CPT charging solutions based on inductive power transfer (IPT) have been developed from laboratory level as a first step to the practical tests of commercial realizations. In a few industrial fields nowadays, some of the proposed CPT technologies with specific coupler coil designs have been expected for real-world applications. This article presents a state of the art of the CPT technologies and focuses on reviewing current coil designs for high-power contactless energy transfer for EVs in the literature
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Design and analysis of a novel CPT system with soft ferromagnetic material cores and electromagnetic resonant coupling for EVs
This paper describes a novel contactless power transfer (CPT) system with geometrically improved H-shape ferromagnetic cores and electromagnetically prospective modelling analysis methods for wireless power transmitting (WPT) applications of electric vehicles (EVs). A CPT prototype, using optimized H-shaped magnetic couplers and series-to-series (SS) compensation, is proposed to address and ensure the maximization of system efficiency, power transfer ratings, and air gaps of coupling coils. By focusing on the main factors such as various system operating frequencies, different geometric designs of coils, changeable inductive coupling distances, electromagnetic field performances and actual phase angle deviations when the inductive coupling system tends to be stable with its waveforms, this small-sized H-shape CPT system has been analytically considered and modelled in a finite-element method (FEM) environment, resulting in a maximum system efficiency of 59.5%, a coil transmitting efficiency of 83.8% and a maximum power output of 42.81 kW on the load end when the resonant coupling of CPT system tends to occur within a range of calculated resonant frequencies, with an air gap of 10 mm. Moreover, the system efficiency and coil transmitting efficiency can reach 47.75% and 77.22%, respectively, and the highest RMS real power to load can achieve 31.95 kW with an air gap of 20 mm. Besides, with an air gap of 30mm, this H-shape CPT system is measured to output 20.39-kW RMS power, along with the maximum system efficiency and coil efficiency of 41.78% and 63.23%, respectively. Furthermore, the improvements of flux linkage, magnetic flux density regarding the actual electromagnetic performance produced and the issues on the calculated natural resonant frequencies have been studied by result analysis and comparison of electromagnetic field parameters generated. In addition, the current limitations and further design considerations have been discussed in this paper
Self-prompted Chain-of-Thought on Large Language Models for Open-domain Multi-hop Reasoning
In open-domain question-answering (ODQA), most existing questions require
single-hop reasoning on commonsense. To further extend this task, we officially
introduce open-domain multi-hop reasoning (ODMR) by answering multi-hop
questions with explicit reasoning steps in open-domain setting. Recently, large
language models (LLMs) have found significant utility in facilitating ODQA
without external corpus. Furthermore, chain-of-thought (CoT) prompting boosts
the reasoning capability of LLMs to a greater extent with manual or automated
paradigms. However, existing automated methods lack of quality assurance, while
manual approaches suffer from limited scalability and poor diversity, hindering
the capabilities of LLMs. In this paper, we propose Self-prompted
Chain-of-Thought (SP-CoT), an automated framework to mass-produce high quality
CoTs of LLMs, by LLMs and for LLMs. SP-CoT introduces an automated generation
pipeline of high quality ODMR datasets, an adaptive sampler for in-context CoT
selection and self-prompted inference via in-context learning. Extensive
experiments on four multi-hop question-answering benchmarks show that our
proposed SP-CoT not only significantly surpasses the previous SOTA methods on
large-scale (175B) LLMs, but also nearly doubles the zero-shot performance of
small-scale (13B) LLMs. Further analysis reveals the remarkable capability of
SP-CoT to elicit direct and concise intermediate reasoning steps by recalling
50\% of intermediate answers on MuSiQue-Ans dataset.Comment: Accepted by Findings of EMNLP202
Capacity sharing, product differentiation and welfare
This article constructs a duopoly market with product differentiation
and analyses profits, consumer surplus and social welfare
under three conditions: (a) two enterprises have sufficient capacity;
(b) one enterprise has insufficient capacity, and another
enterprise has excess capacity that is not shared; and (c) one
enterprise has insufficient capacity, and another enterprise has
excess capacity and engages in capacity sharing. Through comparison,
the implementation conditions for and effects of capacity
sharing and the role of product differentiation are revealed. The
results show that capacity sharing helps increase producer surplus
and social welfare. Capacity constraints reduce social welfare but
can be solved by capacity sharing. Capacity sharing can only be
realised when both enterprises are profitable, and the charge for
capacity sharing should not be too high or too low. Product differentiation
has impacts on output, profit, consumer surplus and
social welfare, and these impacts are restricted by the existence
of capacity constraints and capacity sharing
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