18,921 research outputs found
Asymptotic entanglement capacity of the Ising and anisotropic Heisenberg interactions
We compute the asymptotic entanglement capacity of the Ising interaction ZZ,
the anisotropic Heisenberg interaction XX + YY, and more generally, any
two-qubit Hamiltonian with canonical form K = a XX + b YY. We also describe an
entanglement assisted classical communication protocol using the Hamiltonian K
with rate equal to the asymptotic entanglement capacity.Comment: 5 pages, 1 figure; minor corrections, conjecture adde
Identification and verification of frequency-domain models for XV-15 tilt-rotor aircraft dynamics
Frequency-domain methods are used to extract the open-loop dynamics of the XV-15 tilt-rotor aircraft from flight test data for the cruise condition (V = 170 knots). The frequency responses are numerically fitted with transfer-function forms to identify equivalent model characteristics. The associated handling quality parameters meet or exceed Level 2, Category A, requirements for fixed-wing military aircraft. Step response matching is used to verify the time-domain fidelity of the transfer-function models for the cruise and hover flight conditions. The transient responses of the model and aircraft are in close agreement in all cases, except for the normal acceleration response to elevator deflection in cruise. This discrepancy is probably due to the unmodeled rotor rpm dynamics. The utility of the frequency-domain approach for dynamics identification and analysis is clearly demonstrated
New geometries for high spatial resolution hall probes
The Hall response function of symmetric and asymmetric planar Hall effect
devices is investigated by scanning a magnetized tip above a sensor surface
while simultaneously recording the topography and the Hall voltage. Hall sensor
geometries are tailored using a Focused Ion Beam, in standard symmetric and new
asymmetric geometries. With this technique we are able to reduce a single
voltage probe to a narrow constriction 20 times smaller than the other device
dimensions. We show that the response function is peaked above the
constriction, in agreement with numerical simulations. The results suggest a
new way to pattern Hall sensors for enhanced spatial resolution.Comment: 12 pages, 5 figures, submitted to Journal of Applied Physic
Investigation into Life Enhancement and Positivity – Theoretical and Empirical Studies on Life Satisfaction
Life satisfaction is an important subject for academic and policy attention at
individual, societal, and global levels. However, there are longstanding
controversies in the research regarding life satisfaction. Confusing use of life
satisfaction-related concepts have been identified. Repositioning the concept of
life satisfaction and critically reviewing life-related satisfaction studies will clarify
these confusions. This analytical commentary presents knowledge on a popular
but contested subject, that of life-related satisfaction. This topic is the focus of my
selected publications, in which I seek to reconceptualise and reframe the
discussion to provide a more comprehensive and meaningful framework for life
satisfaction. In addition, I seek to redirect future studies, applications, and policies,
ultimately leading to more enabled and resilient societies.
Specifically, this analytical commentary illustrates the current state of knowledge,
providing an in-depth and systematic evaluation of the current terminologies
related to life satisfaction and well-being; and highlights the urgency for change.
In this analytical commentary, I seek to consider what authentic life satisfaction
is. Based on my selected published works, together with the professional context
in which the publications were written, this analytical commentary will focus on
and:
I. recognise the deficiencies and problems of contemporary
understandings and use of relevant terms and concepts;
II. make reference to philosophical and psychological thoughts;
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III. review literature within theoretically triangular axes as a frame of
reference, namely, life-deep, life-wide, and life-long; and
IV. propose a new theoretical framework entitled ‘Life Enhancement and
Positivity’ (LEP).
Shifting the paradigm, LEP is formulated to be more meaningful, comprehensive,
precise, and parsimonious, considering both structures and dynamics of life. Two
major structural domains are outlined.
Among my published works, I have selected seven peer-reviewed papers that will
serve as the body of work for this analytical commentary. Five of the papers were
published in internationally recognised journals, and two are articles within two
academic reference books published by the University of Hong Kong and Hong
Kong Polytechnic University respectively. Under the common theme of life
satisfaction, they address different research targets (for example, older and
younger cohorts), variables (for example, health-related, psychosocial-related,
and work-related) and methods (for example, quantitative and qualitative). These
publications, as original contributions to the field, aid the construction of a new
meta-level framework that aims to address the aforementioned controversies and
ambiguities within the context of a complex and intricate situation as well as to
serve as a guide towards a new direction
Study program for encapsulation materials interface for low-cost solar array
The service integrity of the bonded interface in solar cell modules used in solar arrays is addressed. The development of AC impedance as a nondestructive evaluation (NDE) methodology for solar arrays is reported along with development of corrosion models and materials selection criteria for corrosion resistant interfaces
Infection-acquired versus vaccine-acquired immunity in an SIRWS model
Despite high vaccine coverage, pertussis has re-emerged as a public health
concern in many countries. One hypothesis posed for re-emergence is the waning
of immunity. In some disease systems, the process of waning immunity can be
non-linear, involving a complex relationship between the duration of immunity
and subsequent boosting of immunity through asymptomatic re-exposure.
We present and analyse a model of infectious disease transmission to examine
the interplay between infection and immunity. By allowing the duration of
infection-acquired immunity to differ from that of vaccine-acquired immunity,
we explore the impact of the difference in durations on long-term disease
patterns and prevalence of infection.
Our model demonstrates that vaccination may induce cyclic behaviour, and its
ability to reduce the infection prevalence increases with both the duration of
infection-acquired immunity and duration of vaccine-acquired immunity. We find
that increasing vaccine coverage, while capable of leading to an increase in
overall transmission, always results in a reduction in prevalence of primary
infections, with epidemic cycles characterised by a longer interepidemic period
and taller peaks.
Our results show that the epidemiological patterns of an infectious disease
may change considerably when the duration of vaccine-acquired immunity differs
from that of infection-acquired immunity. Our study highlights that for any
particular disease and associated vaccine, a detailed understanding of the
duration of protection and how that duration is influenced by infection
prevalence is important as we seek to optimise vaccination strategies.Comment: 21 pages, 5 figure
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Characterization of silicon nanowire by use of full-vectorial finite element method.
We have carried out a rigorous H-field-based full-vectorial modal analysis and used it to characterize, more accurately, the abrupt dielectric discontinuity of a high index contrast optical waveguide. The full-vectorial H and E fields and the Poynting vector profiles are described in detail. It has been shown through this work that the mode profile of a circular silicon nanowire is not circular and also contains a strong axial field component. The single-mode operation, vector field profiles, modal hybridness, modal ellipticity, and group velocity dispersion of this silicon nanowire are also presented
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