Sharif Digital Repository

In this paper we present a new landmark initialization technique for Bearing-Only Simultaneous Localization and Mapping (SLAM) algorithm. The initialization scheme is a type of the delayed constrained initialization method and is different from previous approaches. In our work, it is shown that the angle between sequential observations measured by a bearing-only sensor such as pan-tilt camera and the distance between the vehicle and landmark plays an important role in landmark localization accuracy. Considering this fact, a proper constrained function that utilizes the rotation angle of the camera is applied between multiple landmark location estimates and the best estimate is selected. The... 

We consider a Dynkin game where the seller possesses additional information compared to the buyer. The additional information is described by a random variable taking finitely many values. We show that the game possesses a value and we provide a necessary and sufficient condition for the existence of a Nash equilibrium. Results are illustrated with an explicit example. © 2018, Iranian Mathematical Society  

Global motion estimation (GME) algorithms have an imperative role in object-based applications. Gradient-based GME is a well known method among these algorithms. Such algorithms require an initial value for their initialization step. Well estimation of this value plays a significant role in the accuracy of GME. This work introduces a simple but efficient technique for initial value prediction of GME. This technique employs a long-term predictor as well as global motions of previous frames. Simulations results demonstrate faster convergence and less computational complexity of the proposed method versus common presented techniques in the literature with almost same efficiency  

We consider two ensembles of qubits dissipating into two overlapping environments, that is, with a certain number of qubits in common that dissipate into both environments. We then study the dynamics of bipartite entanglement between the two ensembles by excluding the common qubits. To get analytical solutions for an arbitrary number of qubits we consider initial states with a single excitation and show that the largest amount of entanglement can be created when excitations are initially located among side (noncommon) qubits. Moreover, the stationary entanglement exhibits a monotonic (nonmonotonic) scaling versus the number of common (side) qubits  

Parameter extraction of the five-parameter single-diode model of solar cells and modules from experimental data is a challenging problem. These parameters are evaluated from a set of nonlinear equations that cannot be solved analytically. On the other hand, a numerical solution of such equations needs a suitable initial guess to converge to a solution. This paper presents a new set of approximate analytical solutions for the parameters of a five-parameter single-diode model of photovoltaic (PV) cells and modules. The proposed solutions provide a good initial point which guarantees numerical analysis convergence. The proposed technique needs only a few data from the PV current-voltage... 

Background: Ligament reconstruction is a common procedure in orthopedic surgery. Although several popular techniques are currently in use, new methods are proposed for secure fixation of the tendon graft into the bone tunnel. Purposes: We sought to introduce our new technique of Bashti bone plug for fixation of soft tissue graft in anterior cruciate ligament (ACL) reconstruction and to compare its biomechanical features with conventional absorbable interference screw technique in a bovine model. Methods: Twenty pairs of bovine knees were harvested after death. Soft tissue was removed and the Achilles tendon was harvested to be used as an ACL graft. It was secured into the bone tunnel on the... 

Ordinary frequently occur as mathematical models in many fields of science, engineering, differential equations (ODEs) and economy. It is rarely that ODEs have closed form analytical solutions, so it is common to seek approximate solutions by means of numerical methods. One of the most useful methods for the solution of ODEs is multi-step methods. Although the existing multi-step methods such as Adams—Moulton are accurate and useful, they also have their own limitations such as instability at large step sizes or weak performance in the case of stiff ODEs. Thus, multi-step methods that show better behavior compared to the existing methods are preferred, because they decrease the computational... 

We consider an American contingent claim on a financial market where the buyer has additional information. Both agents (seller and buyer) observe the same prices, while the information available to them may differ due to some extra exogenous knowledge the buyer has. The buyer's information flow is modeled by an initial enlargement of the reference filtration. It seems natural to investigate the value of the American contingent claim with asymmetric information. We provide a representation for the cost of the additional information relying on some results on reflected backward stochastic differential equations (RBSDE). This is done by using an interpretation of prices of American contingent... 

Present study concerns the safety evaluation of SefidRud dam's block No. 18 regarding probable crack propagation in the foundation gallery under a MCE record. Accordingly, a 3D finite element model of the block in companion with the reservoir and the foundation is modeled. All the associated thermal and structural parameters are derived via calibration with the records of thermometers and pendulums installed inside the dam body. The origination of the cracks and their whereabouts are determined by primary thermal and static analyses and through a linear dynamic analysis the potential failure zone and their extent and level are studied. The foundation gallery is the most probable zone among... 

This paper derives an estimated function made by simple Neural Network to find initial state of optimization parameters. It changes a system of differential equations with boundary values to a system of equations with initial values. So a lot of time would be saved to solve it. As a result, the system with differential equations will reach the desired final state. Copyright © 2006 by ASME  

The initial buckling load of a tube corresponds to the peak load in the first buckling cycle. In practice, this load is very important for crashworthiness design that gives an indication of the force required to initiate collapse and hence begin the energy absorption process. In this paper, the effects of grooves on the initial buckling load of thin-walled tubes under axial compression are investigated. The grooves are introduced in the tube to force the plastic deformation to occur at predetermined intervals along the tube. The aims are improve the uniformity of the load-displacement behaviour of axially crushed tubes, predict and control the collapse load of the tube. An analytical study... 

Consider a set of nested infinitely extended elastic cylindrical bodies possessing general cylindrical anisotropy embedded in an unbounded elastic isotropic medium. For general far-field loading, the nature of the elastic fields inside the inhomogeneities is predicted and a number of pertinent attractive properties is noted and proved. Moreover, the associated equivalent inclusion method (EIM) is concisely formulated. The concepts of the homogenization, spectral consistency conditions, and the so-called Eshelby-Fourier tensor are introduced. As a result the tedious and lengthy algebra encountered in the conventional EIM is circumvented and the corresponding large number of unknowns is... 

In this study, we applied the homotopy perturbation (HP) method for solving linear and nonlinear fourth-order boundary value problems. The analytical results of the boundary value problems have been obtained in terms of a convergent series with easily computable components. Comparisons between the results of the HP method and the analytical solution showed that this method gives very precise results with a few terms. In the implied HP method, some unknown parameters in the initial guess are introduced, which are identified after applying boundary conditions. This improvement results in higher accuracy. © 2008 The Royal Swedish Academy of Sciences  

Cavity quantum electrodynamics of multipartite systems are studied in depth, which consists of an arbitrary number of emitters in interaction with an arbitrary number of cavity modes. The governing model is obtained by taking the full field-dipole and dipole-dipole interactions into account, and is solved in the Schrödinger picture with assumption of vanishing field and dipole interactions at high energies. An extensive code is developed that is able to solve the system and track its evolution in time, while maintaining sufficient degrees of arbitrariness in setting up the initial conditions and interacting partitions. Using this code, we have been able to numerically evaluate various... 

In a multi-agent system, the number and initial position of informed agents play a major role in the convergence of uninformed agents. In this paper, three different patterns of informed agents' initial positions are studied to see how the convergence percentage can be affected by the number of informed agents. The proposed initial locations are intuitive and inferred from the collective behavior in humans. To evaluate efficiency of the proposed methods and to compare them from different points of view, large number of computer simulations is performed and results are analyzed