8,877 research outputs found
The observation of a positive magnetoresistance and close correlation among lattice, spin and charge around TC in antipervoskite SnCMn3
The temperature dependences of magnetization, electrical transport, and
thermal transport properties of antiperovskite compound SnCMn3 have been
investigated systematically. A positive magnetoresistance (~11%) is observed
around the ferrimagnetic-paramagnetic transition (TC ~ 280 K) in the field of
50 kOe, which can be attributed to the field-induced magnetic phase transition.
The abnormalities of resistivity, Seebeck coefficient, normal Hall effect and
thermal conductivity near TC are suggested to be associated with an abrupt
reconstruction of electronic structure. Further, our results indicate an
essential interaction among lattice, spin and charge degrees of freedom around
TC. Such an interaction among various degrees of freedom associated with sudden
phase transition is suggested to be characteristic of Mn-based antiperovskite
compounds.Comment: 13 pages, 5 figure
Portfolio configuration and foreign entry decisions: A juxtaposition of real options and risk diversification theories
Research Summary Research on foreign market entry has rarely considered that multinational firms' new entries may be affected by the configuration of their existing affiliates. We argue that in making entry decisions, firms take into account how an entry into a new location helps increase the operational flexibility of their affiliate portfolios due to options to switch operations across affiliates in case of diverging labor cost developments across host countries. We juxtapose this real options‐based explanation with a risk diversification explanation. Analysis of Japanese multinational firms' foreign entry decisions suggests that the two explanations are complementary. We also establish portfolio‐level boundary conditions to the influence of operational flexibility considerations on entry, in the form of product diversification and the nature of dispersion of labor cost levels. Managerial Summary When deciding on whether to enter a foreign market, managers of a multinational firm are intuitively aware that they need to consider how the economic environment of the target host country is related to the environments of the existing countries in which the firm operates. The less the environments are correlated with each other, whether in terms of input cost or market demand conditions, the greater the chance that the firm may capture cost savings and reduce sales volatility globally. These benefits arise from a switching option to shift operations flexibly across countries and from an ability to reduce risk by holding a portfolio of diversified global investments. Our findings support both sets of considerations, suggesting that companies do give due attention to correlations in labor cost and market demand between the target host country to enter and the existing host countries
Comparison of chemical profiles and effectiveness between Erxian decoction and mixtures of decoctions of its individual herbs : a novel approach for identification of the standard chemicals
Acknowledgements This study was partially supported by grants from the Seed Funding Programme for Basic Research (Project Number 201211159146 and 201411159213), the University of Hong Kong. We thank Mr Keith Wong and Ms Cindy Lee for their technical assistances.Peer reviewedPublisher PD
Antenna Array Enabled Space/Air/Ground Communications and Networking for 6G
Antenna arrays have a long history of more than 100 years and have evolved
closely with the development of electronic and information technologies,
playing an indispensable role in wireless communications and radar. With the
rapid development of electronic and information technologies, the demand for
all-time, all-domain, and full-space network services has exploded, and new
communication requirements have been put forward on various space/air/ground
platforms. To meet the ever increasing requirements of the future sixth
generation (6G) wireless communications, such as high capacity, wide coverage,
low latency, and strong robustness, it is promising to employ different types
of antenna arrays with various beamforming technologies in space/air/ground
communication networks, bringing in advantages such as considerable antenna
gains, multiplexing gains, and diversity gains. However, enabling antenna array
for space/air/ground communication networks poses specific, distinctive and
tricky challenges, which has aroused extensive research attention. This paper
aims to overview the field of antenna array enabled space/air/ground
communications and networking. The technical potentials and challenges of
antenna array enabled space/air/ground communications and networking are
presented first. Subsequently, the antenna array structures and designs are
discussed. We then discuss various emerging technologies facilitated by antenna
arrays to meet the new communication requirements of space/air/ground
communication systems. Enabled by these emerging technologies, the distinct
characteristics, challenges, and solutions for space communications, airborne
communications, and ground communications are reviewed. Finally, we present
promising directions for future research in antenna array enabled
space/air/ground communications and networking
On Propagation Characteristics of Reconfigurable Surface Wave Platform: Simulation and Experimental Verification
Reconfigurable intelligent surface (RIS) as a smart reflector is
revolutionizing research for next-generation wireless communications.
Complementing this is a concept of using RIS as an efficient propagation medium
for potentially superior path loss characteristics. Motivated by a recent
porous surface architecture that facilitates reconfigurable pathways with
cavities filled with fluid metal, this paper studies the propagation
characteristics of different pathway configurations in different lossy
materials on the reconfigurable surface wave platform by using a commercial
full electromagnetic simulation software and S-parameters experiments. This
paper also looks into the best scheme to switch between a straight pathway and
a -bend and attempts to quantify the additional path loss when making
a turn. Our experimental results verify the simulation results, showing the
effectiveness of the proposed reconfigurable surface wave platform for a
wide-band, low path loss and highly programmable communications.Comment: Submitted to IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, 202
A Unified Quantum NOT Gate
We study the feasibility of implementing a quantum NOT gate (approximate)
when the quantum state lies between two latitudes on the Bloch's sphere and
present an analytical formula for the optimized 1-to- quantum NOT gate. Our
result generalizes previous results concerning quantum NOT gate for a quantum
state distributed uniformly on the whole Bloch sphere as well as the phase
covariant quantum state. We have also shown that such 1-to- optimized NOT
gate can be implemented using a sequential generation scheme via matrix product
states (MPS)
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