1,126 research outputs found
Quantum Discord for Generalized Bloch Sphere States
In this study for particular states of bipartite quantum system in 2n?2m
dimensional Hilbert space state, similar to m or n-qubit density matrices
represented in Bloch sphere we call them generalized Bloch sphere states(GBSS),
we give an efficient optimization procedure so that analytic evaluation of
quantum discord can be performed. Using this optimization procedure, we find an
exact analytical formula for the optimum positive operator valued measure
(POVM) that maximize the measure of the classical correlation for these states.
The presented optimization procedure also is used to show that for any concave
entropy function the same POVMs are sufficient for quantum discord of mentioned
states. Furthermore, We show that such optimization procedure can be used to
calculate the geometric measure of quantum discord (GMQD) and then an explicit
formula for GMQD is given. Finally, a complete geometric view is presented for
quantum discord of GBSS. Keywords: Quantum Discord, Generalized Bloch Sphere
States, Dirac matrices, Bipartite Quantum System. PACs Index: 03.67.-a,
03.65.Ta, 03.65.UdComment: 26 pages. arXiv admin note: text overlap with arXiv:1107.5174 by
other author
Charge Transport Scalings in Turbulent Electroconvection
We describe a local-power law scaling theory for the mean dimensionless
electric current in turbulent electroconvection. The experimental system
consists of a weakly conducting, submicron thick liquid crystal film supported
in the annulus between concentric circular electrodes. It is driven into
electroconvection by an applied voltage between its inner and outer edges. At
sufficiently large voltage differences, the flow is unsteady and electric
charge is turbulently transported between the electrodes. Our theoretical
development, which closely parallels the Grossmann-Lohse model for turbulent
thermal convection, predicts the local-power law . and are dimensionless
numbers that are similar to the Rayleigh and Prandtl numbers of thermal
convection, respectively. The dimensionless function , which is
specified by the model, describes the dependence of on the aspect ratio
. We find that measurements of are consistent with the theoretical
model.Comment: 12 pages, 7 figures, Submitted to Phys. Rev. E. See also
http://www.physics.utoronto.ca/nonlinea
Development of city centres in Saudi Arabia : development of the Justice Palace district, Arriyadh
Integrating value chain transparency into E-commerce design
Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2010.Cataloged from PDF version of thesis.Includes bibliographical references (p. 75-76).Value chain transparency, such as publishing member biographies and profit distribution, can be a powerful tool in increasing consumer trust and consumer loyalty. This thesis provides a methodology for integrating value chain transparency into Ecommerce site design and makes preliminary findings of the positive influence this strategy has on consumer buying behavior. The design and implementation of integrating value chain information within an E-commerce site is demonstrated through the development of theargantree.com. The Argan Tree is a cooperative of 18 women based in southwestern Morocco who produce argan oil. theargantree.com connects these producers to consumers in the U.S. to sell this oil for its culinary and cosmetic benefits. The implications of this study can transform the cooperative landscape, which is often marked by low wages, a lack of accountability, and difficulty competing in high-end markets. By equipping these organizations with the Internet-based strategies proposed, cooperatives can overcome these challenges and serve as organizations capable of real poverty-alleviation. While the direct application of this thesis is aimed at producer cooperatives of under-privileged populations, the underlying theories and findings can support any retail organization.by Zahir Dossa.M.Eng
A positive approach to sustainability
Thesis (Ph. D. in Sustainable Development)--Massachusetts Institute of Technology, Dept. of Urban Studies and Planning, 2013.Cataloged from PDF version of thesis.Includes bibliographical references.Sustainability is a complex term that is becoming increasingly used. While extremely important, sustainability is often misused and misunderstood, yielding undesirable effects. Furthermore, many organizations promote the image of being sustainable without embracing it, otherwise known as green-washing, yet those that truly are sustainable face difficulty communicating their sustainability practices and distinguishing themselves as such. Despite its complexity, sustainability remains an important term that necessitates a greater conceptualization. In this dissertation, three topics in sustainability (sustainability performance, sustainability innovation, and sustainable development) are explored through a positive approach. A positive approach, also referred to as an abundance approach, is one that espouses a greater understanding for how the highest ideals and fullest potential can be achieved as opposed to one that focuses on fixing immediate problems. Borrowing from positive organizational scholarship (POS) theory and the positive organizational ethics (POE) literature, a framework for capturing sustainability performance is developed in Chapter 2 that shifts the emphasis from minimizing negative externalities to maximizing positive outcomes. Extending upon POS theory, the crisis-PEN-innovation framework advanced in Chapter 3 aligns various literature on innovation to postulate that sustainability innovations are achieved through the formation of positive ethical networks (PENs) that arise in response to external crises. Finally in Chapter 4, a PEN analysis is conducted to foster a greater understanding of project trajectories and outcomes in the sustainable development field. It is therefore through the lenses provided by the POS and POE literatures that new frameworks for conceptualizing topics in sustainability can be developed.by Zahir Dossa.Ph.D.in Sustainable Developmen
Electrically driven convection in a thin annular film undergoing circular Couette flow
We investigate the linear stability of a thin, suspended, annular film of
conducting fluid with a voltage difference applied between its inner and outer
edges. For a sufficiently large voltage, such a film is unstable to
radially-driven electroconvection due to charges which develop on its free
surfaces. The film can also be subjected to a Couette shear by rotating its
inner edge. This combination is experimentally realized using films of smectic
A liquid crystals. In the absence of shear, the convective flow consists of a
stationary, azimuthally one-dimensional pattern of symmetric, counter-rotating
vortex pairs. When Couette flow is applied, an azimuthally traveling pattern
results. When viewed in a co-rotating frame, the traveling pattern consists of
pairs of asymmetric vortices. We calculate the neutral stability boundary for
arbitrary radius ratio and Reynolds number of the shear
flow, and obtain the critical control parameter and the critical azimuthal mode number . The
Couette flow suppresses the onset of electroconvection, so that . The calculated suppression is
compared with experiments performed at and .Comment: 17 pages, 2 column with 9 included eps figures. See also
http://mobydick.physics.utoronto.c
Predicting and Controlling Fertility Using Family Planning Methods
Without a real reduction in population fertility rates, developing societies will push for more spending on their infrastructure and more demand for basic services for new-born, and more dependency and crowding, and the attendant ills and various social, economic and cultural problems, which will push these countries towards Directing a large part (if not most) of development revenues to meet the growing population. In general, the importance of this study lies in how to predict fertility rates using the rates of family planning methods (practice rates, years of protection) and to identify the method of neural networks and its accuracy in dealing with fertility data in particular. The study concluded that the prevalence of family planning methods (PR) and protection rate (CYP) are used to estimate and predict the total fertility rate (TFR) very efficiently, and artificial neu6ral networks have reached a high rate and high accuracy in estimating and predicting the total fertility rate (TFR) is highly and reliable (99.6%)
Deep learning for robust adaptive inverse control of nonlinear dynamic systems: Improved settling time with an autoencoder
An adaptive deep neural network is used in an inverse system identification setting to approximate the inverse of a nonlinear plant with the aim of constituting the plant controller by copying to the latter the weights and architecture of the converging deep neural network. This deep learning (DL) approach to the adaptive inverse control (AIC) problem is shown to outperform the adaptive filtering techniques and algorithms normally used in adaptive control, especially when in nonlinear plants. The deeper the controller, the better the inverse function approximation, provided that the nonlinear plant has an inverse and that this inverse can be approximated. Simulation results prove the feasibility of this DL-based adaptive inverse control scheme. The DL-based AIC system is robust to nonlinear plant parameter changes in that the plant output reassumes the value of the reference signal considerably faster than with the adaptive filter counterpart of the deep neural network. The settling and rise times of the step response are shown to improve in the DL-based AIC system
Deep learning control for digital feedback systems: Improved performance with robustness against parameter change
Training data for a deep learning (DL) neural network (NN) controller are obtained from the input and output signals of a conventional digital controller that is designed to provide the suitable control signal to a specified plant within a feedback digital control system. It is found that if the DL controller is sufficiently deep (four hidden layers), it can outperform the conventional controller in terms of settling time of the system output transient response to a unit-step reference signal. That is, the DL controller introduces a damping effect. Moreover, it does not need to be retrained to operate with a reference signal of different magnitude, or under system parameter change. Such properties make the DL control more attractive for applications that may undergo parameter variation, such as sensor networks. The promising results of robustness against parameter changes are calling for future research in the direction of robust DL control
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