2,920 research outputs found
Cooperation and Underlay Mode Selection in Cognitive Radio Network
In this research, we proposes a new method for cooperation and underlay mode
selection in cognitive radio networks. We characterize the maximum achievable
throughput of our proposed method of hybrid spectrum sharing. Hybrid spectrum
sharing is assumed where the Secondary User (SU) can access the Primary User
(PU) channel in two modes, underlay mode or cooperative mode with admission
control. In addition to access the channel in the overlay mode, secondary user
is allowed to occupy the channel currently occupied by the primary user but
with small transmission power. Adding the underlay access modes attains more
opportunities to the secondary user to transmit data. It is proposed that the
secondary user can only exploits the underlay access when the channel of the
primary user direct link is good or predicted to be in non-outage state.
Therefore, the secondary user could switch between underlay spectrum sharing
and cooperation with the primary user. Hybrid access is regulated through
monitoring the state of the primary link. By observing the simulation results,
the proposed model attains noticeable improvement in the system performance in
terms of maximum secondary user throughput than the conventional cooperation
and non-cooperation schemes
Nonlinearly charged Lifshitz black holes for any exponent
Charged Lifshitz black holes for the Einstein-Proca-Maxwell system with a
negative cosmological constant in arbitrary dimension are known only if the
dynamical critical exponent is fixed as . In the present work, we
show that these configurations can be extended to much more general charged
black holes which in addition exist for any value of the dynamical exponent
by considering a nonlinear electrodynamics instead of the Maxwell theory.
More precisely, we introduce a two-parametric nonlinear electrodynamics defined
in the more general, but less known, so-called -formalism and
obtain a family of charged black hole solutions depending on two parameters. We
also remark that the value of the dynamical exponent turns out to be
critical in the sense that it yields asymptotically Lifshitz black holes with
logarithmic decay supported by a particular logarithmic electrodynamics. All
these configurations include extremal Lifshitz black holes. Charged topological
Lifshitz black holes are also shown to emerge by slightly generalizing the
proposed electrodynamics
Institutions and Mechanisms for Internal Conflict Resolution: Legal and Non-Legal Means in Resolving Dispute and Attaining Justice in Malaysia
Seeking justice is a noble cause and dispensing justice is an obligation that the state must fulfill. Under the doctrine of separation of powers courts exist to protect people and their rights, to guarantee fairness and justice for all. The task to combat injustices, produce a just ordering of society, ensure a fair distribution of material and legal resources, safeguard the rule of law, promote equality, ensure proportionality in punishment, and protect entitlements and legitimate expectations should not be put on the shoulders of judges and courts only. It must be spread out and shared by other institutions and by whatever means availabl
Numerical solutions of two-point boundary value problems in Chebyshev series
Series expressed in terms of Chebyshev polynomials are applied using Lie series to the iterative solution of ordinary differential equations. After a discussion of initial value problems, the method is then used to solve two-point boundary value problems and an improved method of shooting type is derived and tested
Higher-dimensional black holes with a conformally invariant Maxwell source
We consider an action for an abelian gauge field for which the density is
given by a power of the Maxwell Lagrangian. In d spacetime dimensions this
action is shown to enjoy the conformal invariance if the power is chosen as
d/4. We take advantage of this conformal invariance to derive black hole
solutions electrically charged with a purely radial electric field. Because of
considering power of the Maxwell density, the black hole solutions exist only
for dimensions which are multiples of four. The expression of the electric
field does not depend on the dimension and corresponds to the four-dimensional
Reissner-Nordstrom field. Using the Hamiltonian action we identify the mass and
the electric charge of these black hole solutions.Comment: 5 page
Geometry-material coordination for passive adaptive solar morphing envelopes
The cost-intensive and mechanical complexity natures of the adaptive facades of the past decades drifted designers and researchers’ interest towards passive material-based actuation systems. Architectural applications using the latter showed, however, a few limitations restricting the output possibility space to options that rely entirely on one material’s phase characteristic. This study aims to investigate the potential of expanding a shape memory alloy-actuated facade’s output from one that is limited and hardly controllable in the case of entirely passive actuation to one that can produce a specific desired performative target. This is explored through coordinating between geometry movement connections of an adaptive component of four integrated shape memory alloys, which work on tailoring the geometry-material-climate relations of the responsive system. The research findings suggest that the integration of geometry, material, and their connections in the design of a SMA solar morphing envelope lead to the development of a wider range of behavioural system outputs. The variety instilled through these added dimensions promoted diversity and adaptability of output for a flexible range of responses and higher performative gains
Neighbourhood Shading Impacts on Passive Adaptive Façade Collective Behaviour
The past decade witnessed a shift in adaptive facades from energy-intensive complex systems to material-based actuated facades. The latter, however, were only developed with limited control in shape memory alloy applications, and more generally designed as independent components. The perception of the component within a system as a self-regulating entity was shown to widen the behavioural response and intelligence of an adaptive system in several projects. On the other hand, its range of impact and integration as a design factor were not targeted at full breadth in the literature. The study’s objective was to investigate the incorporation of neighbourhood shading behaviour of a shape memory alloy-actuated façade component on the entire system. Based on a designed adaptive component, the research identifies the shading impact on the actuators’ incident solar radiation as well as its hourly and seasonal range, and thus encourages a better prediction of collective behaviour
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