Sharif Digital Repository

The de Broglie-Bohm interpretation of quantum mechanics with and without spin-dependence is used to determine electron trajectories, arrival-time distribution of electrons and the mean arrival time of spin-1/2 particles (including electrons) in the presence of a uniform field and a barrier separately. The difference for the mean arrival times, which are calculated with different guidance equations, is examined versus mass of the arriving particle and versus group velocity of the arriving electron wave packet and also versus the width of the barrier. Numerical calculations show that these differences are of the order of 10-18-10-17 s. Another feature of the modified guidance law is that... 

In this work we assume that there is an agent in an unknown environment (domain). This agent has some predefined actions and it can perceive its current state in the environment completely. The mission of this agent is to fulfill the tasks (goals) that are often assigned to it as fast as it can. Acting has lots of cost, and usually planning and simulating the environment can reduce this cost. In this paper we address a new approach for incremental induction of probabilistic planning operators, from this environment while the agent tries to reach to its current goals. It should be noted that there have been some works related to incremental induction of deterministic planning operators and... 

In this paper we show how the higher index theory can be used to prove results concerning the non-existence of a complete Riemannian metric with uniformly positive scalar curvature at infinity. By improving some classical results due to M. Gromov and B. Lawson we show the efficiency of these methods to prove such non-existence theorems  

This paper presents stability analysis of a distributed generation (DG) controller (1), in an islanded mode, based on the Mapping Theorem and the Zero Exclusion Condition, and validates the results based on a laboratory scale experimental setup. The DG unit is interfaced to the host system through a voltage-sourced converter (VSC). The control strategy regulates the load voltage at the desired value in the islanded mode, despite uncertainties in the load parameters. The frequency of the island is controlled in an open loop manner by an internal oscillator. The experimental results show that the controller provides robust voltage control for a wide range of load parameters, and even maintains... 

Purpose: In this paper, the joint replenishment problem is modeled for a two-level supply chain consisting of a single supplier and multiple retailers that use the vendor-managed inventory (VMI) policy for several products. This paper aims to find the optimal number of products to order in both policies, the optimal times at which each retailer orders the products in the traditional policy and the optimal times at which the supplier orders the product in the VMI policy. Design/methodology/approach: The problem is first formulated into the framework of a constrained integer nonlinear programming model; then, the problem is solved using a teacher-learner based optimization algorithm. As there... 

It has been pointed out that the numerical simulation results presented in the above paper are not consistent with reality. The reason for this inconsistency has analytically been clarified in this note. © 2009 IEEE  

In this paper, we present design and implementation of TCvisor, a new trusted hypervisor. To this end, TCvisor provides a secure storage with different isolated view per user by using para-passthrough and combined key. In this regard, virtualization technology of processors has been used for complete isolation from operating system. By combining TPM base key, user's password and geo function key, TCvisor provides a secure storage in an environment with split data. We have applied feature wise security analysis TCvisor's secure storage from software system layers point then we have compared performance of TCvisor to selected candidates of existing layers  

We introduce a universal and systematic way of defining a generalized B-spline based on a linear shift-invariant (LSI) operator L (a.k.a. Fourier multiplier). The generic form of the B-spline is βL=LdL−1δ where L−1δ is the Green's function of L and where Ld is the discretized version of the operator that has the smallest-possible null space. The cornerstone of our approach is a main construction of Ld in the form of an infinite product that is motivated by Weierstrass’ factorization of entire functions. We show that the resulting Fourier-domain expression is compatible with the construction of all known B-splines. In the special case where L is the derivative operator (linked with... 

We introduce a general method of gluing multi-partite states and show that entanglement swapping is a special class of a wider range of gluing operations. The gluing operation of two m and n qudit states consists of an entangling operation on two given qudits of the two states followed by operations of measurements of the two qudits in the computational basis. Depending on how many qudits (two, one or zero) we measure, we have three classes of gluing operation, resulting respectively in m+ n- 2 , m+ n- 1 , or m+ n qudit states. Entanglement swapping belongs to the first class and has been widely studied, while the other two classes are presented and studied here. In particular, we study how... 

In the present research, human errors existed in tasks of operators working in two control rooms (Northern and Southern control rooms) in the Tehran oil refinery are identified and evaluated. Then, corrective strategies and actions are advised to decrease errors. At first, using hierarchical task analysis (HTA) method, four positions including shift controller, head operators, control room's operators, and outside operators are analyzed. Afterwards, human errors in the considered positions are identified and assessed using technique for retrospective and predictive analysis of cognitive errors (TRACEr). Results present 670 internal errors and 738 external errors in the Northern sector while... 

Dispersed phase holdup has been measured in a 76 mm diameter pulsed disc and doughnut extraction column for three different liquid-liquid systems. The effects of operational variables such as pulsation intensity and dispersed and continuous phase flow rates on holdup have been investigated and found to be significant. The existence of three different operational regimes, namely mixer-settler, dispersion, and emulsion regimes, was observed when the energy input was changed. The results indicated that the characteristic velocity approach is applicable to this type of extraction column for analysis of holdup in the transition and emulsion regions. Empirical correlations are derived for... 

In this paper a new post fault operation strategy is proposed for modular multilevel converter (MMC). The conventional MMC fault tolerant operation methods use redundant cells in spinning or cold reserve schemes, however in this work the MMC fault tolerant operation is achieved without requiring any redundant cells. The introduced strategy modifies capacitors reference voltages and arms modulation reference waveforms in faulty leg of MMC while other legs operate normally. The applied technique leads to having some degree of overvoltage in faulty leg capacitors which could be neglected since the number of cells is high. Simple realization and significant economic savings would be attained as... 

We introduce a universal and systematic way of defining a generalized B-spline based on a linear shift-invariant (LSI) operator L (a.k.a. Fourier multiplier). The generic form of the B-spline is . βL=LdL-1δ where . L-1δ is the Green's function of L and where . Ld is the discretized version of the operator that has the smallest-possible null space. The cornerstone of our approach is a main construction of . Ld in the form of an infinite product that is motivated by Weierstrass' factorization of entire functions. We show that the resulting Fourier-domain expression is compatible with the construction of all known B-splines. In the special case where L is the derivative operator (linked with... 

It is first shown that the Dirac's equation in a relativistic frame could be modified to allow discrete time, in agreement to a recently published upper bound. Next, an exact self-adjoint 4 × 4 relativistic time operator for spin-1/2 particles is found and the time eigenstates for the non-relativistic case are obtained and discussed. Results confirm the quantum mechanical speculation that particles can indeed occupy negative energy levels with vanishingly small but non-zero probablity, contrary to the general expectation from classical physics. Hence, Wolfgang Pauli's objection regarding the existence of a self-adjoint time operator is fully resolved. It is shown that using the time... 

In this paper resilience oriented water and energy hub scheduling for a remote area is presented. The optimal operation scheduling considering maintenance programming and reliability indices are presented. Demands which include electricity, heat and drinking waters are supplied by diesel generators, boilers, combined heat and power units, and drinking water sources such as desalination units and transferring water. The considered system contains renewable energy resources such as wind turbine and photovoltaic arrays as well as electrical storage units. In order to enhance resiliency of system against forced outages of components and regular maintenance programs, maintenance constraints and... 

Continuity and reliability of electricity supply in a country are vital to the operational continuity of the critical infrastructure and government. High levels of cyber security are required to achieve such key measures in the electricity industry. We propose solutions and models on how to improve the cyber security using the maturity model in order to achieve continuity of electricity supplies. Maturity levels start from the relative level (level 1) and continue to the adaptive level (level 4). A total of 10 domains are defined in the model. The practices of cyber security are clustered into domains. The model is used for assessment of the strength and weakness factors for the... 

These days, tourist submarine industry has become of increasing interest and prosperity. A tourist submarine operating beneath a seaway suffers different undesired motions which may cause difficulty in operability for the vehicle and habitability of its passengers. From this point of view, this paper studies the hydrodynamic problem of submarine operability in waves. In this investigation strip theory has been used and effects of different parameters of sea state, sea direction, depth, speed and duration of operation have been considered. Results of presented case study indicate that speed effect is insignificant while the operating depth role seems more important  

We have presented a theoretical extended version of dense coding protocol using entangled position state of two particles shared between two parties. A representation of Bell states and the required unitary operators are shown utilizing symmetric normalized Hadamard matrices. In addition, some explicit and conceivable forms for the unitary operators are presented by using some introduced basic operators. It is shown that, the proposed version is logarithmically efficient than some other multi-qubit dense coding protocols. © 2003 Elsevier B.V. All rights reserved