3,865 research outputs found
Actuator and sensor placement in linear advection PDE with building system application
AbstractWe study the problem of actuator and sensor placement in a linear advection partial differential equation (PDE). The problem is motivated by its application to actuator and sensor placement in building systems for the control and detection of a scalar quantity such as temperature and contaminants. We propose a gramian based approach to the problem of actuator and sensor placement. The special structure of the advection PDE is exploited to provide an explicit formula for the controllability and observability gramian in the form of a multiplication operator. The explicit formula for the gramian, as a function of actuator and sensor location, is used to provide test criteria for the suitability of a given sensor and actuator location. Furthermore, the solution obtained using gramian based criteria is interpreted in terms of the flow of the advective vector field. In particular, the almost everywhere stability property of the advective vector field is shown to play a crucial role in deciding the location of actuators and sensors. Simulation results are performed to support the main results of this paper
Cu-based metalorganic systems: an ab initio study of the electronic structure
Within a first principles framework, we study the electronic structure of the
recently synthesized polymeric coordination compound
Cu(II)-2,5-bis(pyrazol-1-yl)-1,4-dihydroxybenzene (CuCCP), which has been
suggested to be a good realization of a Heisenberg spin-1/2 chain with
antiferromagnetic coupling. By using a combination of classical with ab initio
quantum mechanical methods, we design on the computer reliable modified
structures of CuCCP aimed at studying effects of Cu-Cu coupling strength
variations on this spin-1/2 system. For this purpose, we performed two types of
modifications on CuCCP. In one case, we replaced H in the linker by i) an
electron donating group (NH2) and ii) an electron withdrawing group (CN), while
the other modification consisted in adding H2O and NH3 molecules in the
structure which change the local coordination of the Cu(II) ions. With the
NMTO-downfolding method we provide a quantitative analysis of the modified
electronic structure and the nature of the Cu-Cu interaction paths in these new
structures and discuss its implications for the underlying microscopic model.Comment: 18 pages, 11 figures, final versio
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Policy initiatives for strengthening rural economic development in India: Case studies from Madhya Pradesh and Orissa
The purpose of this publication is to present the findings of research concerned with improved understanding and appropriate policy development for the rural non-farm economy (RNFE) in India. The research was undertaken by the Natural Resources Institute (NRI) in collaboration with local partners1; with funding from the UK’s Department for International Development (DFID) under a collaborative agreement with the World Bank. The two Indian states selected for analysis were Madhya Pradesh and Orissa. Research objectives of this study sought to inform policy on two interrelated topics: 1) sources of farm and non-farm income in rural households; barriers to uptake of non-farm employment; and opportunities which can be translated into policy recommendations; 2) the effect of local governance on the development of the RNFE in particular and rural development in general; and the opportunities for making local governments more responsive to local needs
Chemical control of polar behavior in bicomponent short-period superlattices
Using first-principles density functional calculations, we study the
interplay of ferroelectricity and polar discontinuities in a range of 1-1 oxide
superlattices, built out of ferroelectric and paraelectric components. Studies
have been carried out for a varied choice of chemical composition of the
components. We find that, when polar interfaces are present, the polar
discontinuities induce off- centric movements in the ferroelectric layers, even
though the ferroelectric is only one unit cell thick. The distortions yield
non-switchable polarizations, with magnitudes comparable to those of the
corresponding bulk ferroelectrics. In contrast, in superlattices with no polar
discontinuity at the interfaces, the off-centric movements in the ferroelectric
layer are usually suppressed. The details of the behavior and functional
properties are, however, found to be sensitive to epitaxial strain, rotational
instabilities and second-order Jahn-Teller activity, and are therefore strongly
in uenced by the chemical composition of the paraelectric layer.Comment: 7 pages, 2 figure
Early classification of time series by simultaneously optimizing the accuracy and earliness
The problem of early classi cation of time series appears naturally in contexts where the data, of temporal nature, is collected over time, and early class predictions are interesting or even required. The objective is to classify the incoming sequence as soon as possible, while maintaining suitable levels of accuracy in the predictions. Thus, we can say that the problem of early classi cation consists in optimizing two objectives simultaneously: accuracy and earliness. In this context, we present a method for early classi cation of time series based on combining a set of probabilistic classi ers together with a stopping rule. This stopping rule
will act as a trigger and will tell us when to output a prediction or when to wait for more data, and it's main novelty lies in the fact that it is built by explicitly optimizing a cost function based on accuracy and earliness.
We have selected a large set of benchmark datasets and 4 other state-of- the-art early classi cation methods and we have evaluated and compared our framework obtaining superior results in terms of both earliness and accuracy.TIN2016-78365-R, IT-609-1
Electronic structure and magnetism in doped semiconducting half-Heusler compounds
We have studied in details the electronic structure and magnetism in M (Mn
and Cr) doped semiconducting half-Heusler compounds FeVSb, CoTiSb and NiTiSn
(XMYZ) in a wide concentration range using local-spin density
functional method in the framework of tight-binding linearized muffin tin
orbital method(TB-LMTO) and supercell approach. Our calculations indicate that
some of these compounds are not only ferromagnetic but also half-metallic and
may be useful for spintronics applications. The electronic structure of the
doped systems is analyzed with the aid of a simple model where we have
considered the interaction between the dopant transition metal (M) and the
valence band X-Z hybrid. We have shown that the strong X-d - M-d interaction
places the M-d states close to the Fermi level with the M-t states lying
higher in energy in comparison to the M-e states. Depending on the number
of available d-electrons, ferromagnetism is realized provided the d-manifold is
partially occupied. The tendencies toward ferromagnetic(FM) or
antiferromagnetic(AFM) behavior are discussed within Anderson-Hasegawa models
of super-exchange and double-exchange. In our calculations for Mn doped NiTiSn,
the strong preference for FM over AFM ordering suggests a possible high Curie
temperature for these systems.Comment: 14 pages, 6 figure
Dissipative quantum dynamics in low-energy collisions of complex nuclei
Model calculations that include the effects of irreversible, environmental
couplings on top of a coupled-channels dynamical description of the collision
of two complex nuclei are presented. The Liouville-von Neumann equation for the
time-evolution of the density matrix of a dissipative system is solved
numerically providing a consistent transition from coherent to decoherent (and
dissipative) dynamics during the collision. Quantum decoherence and dissipation
are clearly manifested in the model calculations. Energy dissipation, due to
the irreversible decay of giant-dipole vibrational states of the colliding
nuclei, is shown to result in a hindrance of quantum tunneling and fusion.Comment: Accepted in Physical Review
Extended Self-similarity in Kinetic Surface Roughening
We show from numerical simulations that a limited mobility solid-on-solid
model of kinetically rough surface growth exhibits extended self-similarity
analogous to that found in fluid turbulence. The range over which
scale-independent power-law behavior is observed is significantly enhanced if
two correlation functions of different order, such as those representing two
different moments of the difference in height between two points, are plotted
against each other. This behavior, found in both one and two dimensions,
suggests that the `relative' exponents may be more fundamental than the
`absolute' ones.Comment: 4 pages, 4 postscript figures included (some changes made according
to referees' comments. accepted for publication in PRE Rapid Communication
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