199,148 research outputs found
Optimal control of the heave motion of marine cable subsea-unit systems
One of the key problems associated with subsea operations involving tethered subsea units is the motions of support vessels on the ocean surface which can be transmitted to the subsea unit through the cable and increase the tension. In this paper, a theoretical approach for heave compensation is developed. After proper modelling of each element of the system, which includes the cable/subsea-unit, the onboard winch, control theory is applied to design an optimal control law. Numerical simulations are carried out, and it is found that the proposed active control scheme appears to be a promising solution to the problem of heave compensation
Automatic emotional state detection using facial expression dynamic in videos
In this paper, an automatic emotion detection system is built for a computer or machine to detect the emotional state from facial expressions in human computer communication. Firstly, dynamic motion features are extracted from facial expression videos and then advanced machine learning methods for classification and regression are used to predict the emotional states.
The system is evaluated on two publicly available datasets, i.e. GEMEP_FERA and AVEC2013, and satisfied performances are achieved in comparison with the baseline results provided. With this emotional state detection capability, a machine can read the facial expression of its user automatically. This technique can be integrated into applications such as smart robots, interactive games and smart surveillance systems
Concerning resolvent estimates for simply connected manifolds of constant curvature
We prove families of uniform resolvent estimates for simply
connected manifolds of constant curvature (negative or positive) that imply the
earlier ones for Euclidean space of Kenig, Ruiz and the second author
\cite{KRS}. In the case of the sphere we take advantage of the fact that the
half-wave group of the natural shifted Laplacian is periodic. In the case of
hyperbolic space, the key ingredient is a natural variant of the Stein-Tomas
restriction theorem.Comment: 25 pages, 2 figure
Random Beamforming with Heterogeneous Users and Selective Feedback: Individual Sum Rate and Individual Scaling Laws
This paper investigates three open problems in random beamforming based
communication systems: the scheduling policy with heterogeneous users, the
closed form sum rate, and the randomness of multiuser diversity with selective
feedback. By employing the cumulative distribution function based scheduling
policy, we guarantee fairness among users as well as obtain multiuser diversity
gain in the heterogeneous scenario. Under this scheduling framework, the
individual sum rate, namely the average rate for a given user multiplied by the
number of users, is of interest and analyzed under different feedback schemes.
Firstly, under the full feedback scheme, we derive the closed form individual
sum rate by employing a decomposition of the probability density function of
the selected user's signal-to-interference-plus-noise ratio. This technique is
employed to further obtain a closed form rate approximation with selective
feedback in the spatial dimension. The analysis is also extended to random
beamforming in a wideband OFDMA system with additional selective feedback in
the spectral dimension wherein only the best beams for the best-L resource
blocks are fed back. We utilize extreme value theory to examine the randomness
of multiuser diversity incurred by selective feedback. Finally, by leveraging
the tail equivalence method, the multiplicative effect of selective feedback
and random observations is observed to establish the individual rate scaling.Comment: Submitted in March 2012. To appear in IEEE Transactions on Wireless
Communications. Part of this paper builds upon the following letter: Y. Huang
and B. D. Rao, "Closed form sum rate of random beamforming", IEEE Commun.
Lett., vol. 16, no. 5, pp. 630-633, May 201
An Analytical Framework for Heterogeneous Partial Feedback Design in Heterogeneous Multicell OFDMA Networks
The inherent heterogeneous structure resulting from user densities and large
scale channel effects motivates heterogeneous partial feedback design in
heterogeneous networks. In such emerging networks, a distributed scheduling
policy which enjoys multiuser diversity as well as maintains fairness among
users is favored for individual user rate enhancement and guarantees. For a
system employing the cumulative distribution function based scheduling, which
satisfies the two above mentioned desired features, we develop an analytical
framework to investigate heterogeneous partial feedback in a general
OFDMA-based heterogeneous multicell employing the best-M partial feedback
strategy. Exact sum rate analysis is first carried out and closed form
expressions are obtained by a novel decomposition of the probability density
function of the selected user's signal-to-interference-plus-noise ratio. To
draw further insight, we perform asymptotic analysis using extreme value theory
to examine the effect of partial feedback on the randomness of multiuser
diversity, show the asymptotic optimality of best-1 feedback, and derive an
asymptotic approximation for the sum rate in order to determine the minimum
required partial feedback.Comment: To appear in IEEE Trans. on Signal Processin
The Semisecret Life of Late Mao-Era International Law Scholarship
This Article is delimited by a focus on international law scholarship during the late Mao era, not on the PRC’s actual approach to or pronouncements on international law, mainly in order to respond directly to the assertion of U.S.-based international law scholars on late Mao-era scholarship. Of course, considerable ambiguity surrounds what constitutes scholarly work; no legal or even consensus definition generally exists. To be clear, definitions might exist in specific contexts such as the Foreign Agents Registration Act (“FARA”) of the United States, which prohibits foreign lobbying except for “bonafide religious, scholastic, academic or scientific pursuits or the fine arts,” inter alia, although the distinction between scholarly and other types of activities is left entirely ambiguous under the legislation and the case law. In this particular context, Chiu signaled in 1966 what he might have meant by scholarly when he added the qualification to similar assertions from the past that Mao-era international law commentators exhibited “a lack of interest in original studies of international law problems,” suggesting that his definition of scholarly requires an element of originality and intellectual rigor concerning clearly identified problems. Whether the plain-language definition of scholarly contains such elements depends on which dictionary one consults. The Oxford English Dictionary refers to “learned, erudite” for its definition. The Cambridge English Dictionary defines scholarly as “containing a serious, detailed study of a subject,” which suggests the same type of study that a learned or erudite person would undertake. As this Article looks at U.S.based international law scholars, it might be helpful to look at U.S. dictionaries. The Merriam-Webster dictionary provides a similar definition as that of the Oxford English Dictionary— “of, characteristic of, or suitable to learned persons.” Collins Dictionary provides a first definition of “learned” and then a second of “having or showing much knowledge, accuracy, and critical ability.” Of course, accuracy might depend on the viewer’s perspective and the referent employed. Regardless, an amalgam of these definitions would include a large measure of detailed knowledge and serious independence in expressing that detailed knowledge, which presumably would create some form of originality in addressing the problem at issue. This Article uses all three elements—knowledge, independence and originality—to assess whether a particular Mao-era work between 1965 and 1979 represents a scholarly contribution. This is distinguished from non-scholarly contributions, which may relate to education but more closely resemble indoctrination and political propaganda
Performance Analysis of Heterogeneous Feedback Design in an OFDMA Downlink with Partial and Imperfect Feedback
Current OFDMA systems group resource blocks into subband to form the basic
feedback unit. Homogeneous feedback design with a common subband size is not
aware of the heterogeneous channel statistics among users. Under a general
correlated channel model, we demonstrate the gain of matching the subband size
to the underlying channel statistics motivating heterogeneous feedback design
with different subband sizes and feedback resources across clusters of users.
Employing the best-M partial feedback strategy, users with smaller subband size
would convey more partial feedback to match the frequency selectivity. In order
to develop an analytical framework to investigate the impact of partial
feedback and potential imperfections, we leverage the multi-cluster subband
fading model. The perfect feedback scenario is thoroughly analyzed, and the
closed form expression for the average sum rate is derived for the
heterogeneous partial feedback system. We proceed to examine the effect of
imperfections due to channel estimation error and feedback delay, which leads
to additional consideration of system outage. Two transmission strategies: the
fix rate and the variable rate, are considered for the outage analysis. We also
investigate how to adapt to the imperfections in order to maximize the average
goodput under heterogeneous partial feedback.Comment: To appear in IEEE Trans. on Signal Processin
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