338 research outputs found
Energy Efficiency and Quality of Services in Virtualized Cloud Radio Access Network
Cloud Radio Access Network (C-RAN) is being widely studied for soft and green fifth generation of Long Term Evolution - Advanced (LTE-A). The recent technology advancement in network virtualization function (NFV) and software defined radio (SDR) has enabled virtualization of Baseband Units (BBU) and sharing of underlying general purpose processing (GPP) infrastructure. Also, new innovations in optical transport network (OTN) such as Dark Fiber provides low latency and high bandwidth channels that can support C-RAN for more than forty-kilometer radius. All these advancements make C-RAN feasible and practical. Several virtualization strategies and architectures are proposed for C-RAN and it has been established that C-RAN offers higher energy efficiency and better resource utilization than the current decentralized radio access network (D-RAN). This project studies proposed resource utilization strategy and device a method to calculate power utilization. Then proposes and analyzes a new resource management and virtual BBU placement strategy for C-RAN based on demand prediction and inter-BBU communication load. The new approach is compared with existing state of art strategies with same input scenarios and load. The trade-offs between energy efficiency and quality of services is discussed. The project concludes with comparison between different strategies based on complexity of the system, performance in terms of service availability and optimization efficiency in different scenarios
Search-based Motion Planning for Aggressive Flight in SE(3)
Quadrotors with large thrust-to-weight ratios are able to track aggressive
trajectories with sharp turns and high accelerations. In this work, we develop
a search-based trajectory planning approach that exploits the quadrotor
maneuverability to generate sequences of motion primitives in cluttered
environments. We model the quadrotor body as an ellipsoid and compute its
flight attitude along trajectories in order to check for collisions against
obstacles. The ellipsoid model allows the quadrotor to pass through gaps that
are smaller than its diameter with non-zero pitch or roll angles. Without any
prior information about the location of gaps and associated attitude
constraints, our algorithm is able to find a safe and optimal trajectory that
guides the robot to its goal as fast as possible. To accelerate planning, we
first perform a lower dimensional search and use it as a heuristic to guide the
generation of a final dynamically feasible trajectory. We analyze critical
discretization parameters of motion primitive planning and demonstrate the
feasibility of the generated trajectories in various simulations and real-world
experiments.Comment: 8 pages, submitted to RAL and ICRA 201
Pentaquark Masses in Chiral Perturbation Theory
Heavy baryon chiral perturbation theory for pentaquarks is applied beyond
leading order. The mass splitting in the pentaquark anti-decuplet is calculated
up to NNLO. An expansion in the coupling of pentaquarks to non-exotic baryons
simplifies calculations and makes the pentaquark masses insensitive to the
pentaquark-nucleon mass difference. The possibility of determining coupling
constants in the chiral Lagrangian on the lattice is discussed. Both positive
and negative parities are considered.Comment: 11 pages; reference added, minor changes in wordin
Evaluation of methods for analysis of multi-degree-of-freedom systems with damping
A general review of various methods for studying the behavior of linear lumped parameter systems with viscous damping is presented. Five methods are discussed. These are: (1) Normal Mode Technique (2) Ho\u27s Method (3) Impedance Method (4) Graphical Technique (5) A Method for Reducing Degrees-of-freedom. For solution of vibration problems by the Normal Mode Technique, the systems are classified as (1) classically damped or (2) non-classically damped. It is shown that the classically damped systems are relatively easy to solve. For non-classically damped systems, the method proposed by K. A. Foss has been employed. This method is quite complex, but does provide an exact solution in most cases. In Holzer\u27s Method, equations for both undamped and damped systems are derived. A sample table is presented which is employed to solve these equations. Systems having dampers between masses as well as between the masses and ground have been discussed. Also branched systems have been treated. In the Impedance Method, the four-pole parameters of a mass, spring and damper are derived and the formulas for solving tandem and parallel connections are presented. In the Graphical Technique, procedures for arranging the equations of motion in a form suitable for graphical solution are outlined. Application of this method to branched systems is discussed. In the Method for Reducing Degrees-of-Freedom, two problems are presented to illustrate the use of this method. The results obtained have been compared with exact solutions. Advantages and disadvantages of each of these methods are discussed on a comparative basis. A sample problem is solved by all of these methods and the results are compared. Suggestions for further work are mode --Abstract, page ii-iii
Bounded Model Checking of State-Space Digital Systems: The Impact of Finite Word-Length Effects on the Implementation of Fixed-Point Digital Controllers Based on State-Space Modeling
The extensive use of digital controllers demands a growing effort to prevent
design errors that appear due to finite-word length (FWL) effects. However,
there is still a gap, regarding verification tools and methodologies to check
implementation aspects of control systems. Thus, the present paper describes an
approach, which employs bounded model checking (BMC) techniques, to verify
fixed-point digital controllers represented by state-space equations. The
experimental results demonstrate the sensitivity of such systems to FWL effects
and the effectiveness of the proposed approach to detect them. To the best of
my knowledge, this is the first contribution tackling formal verification
through BMC of fixed-point state-space digital controllers.Comment: International Symposium on the Foundations of Software Engineering
201
Dirac Particles in Twisted Tubes
We consider the dynamics of a relativistic Dirac particle constrained to move
in the interior of a twisted tube by confining boundary conditions, in the
approximation that the curvature of the tube is small and slowly varying. In
contrast with the nonrelativistic theory, which predicts that a particle's spin
does not change as the particle propagates along the tube, we find that the
angular momentum eigenstates of a relativistic spin-1/2 particle may behave
nontrivially. For example, a particle with its angular momentum initially
polarized in the direction of propagation may acquire a nonzero component of
angular momentum in the opposite direction on turning through 2 \pi radians.
Also, the usual nonrelativistic effective potential acquires an additional
factor in the relativistic theory.Comment: 16 pages, 3 EPS figures, REVTeX using BoxedEPS package; email to
[email protected]
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