Sharif Digital Repository

The staggered quantum walk is a type of discrete-time quantum-walk model without a coin which can be generated on a graph using particular partitions of the graph nodes. We design Hamiltonians for potential realization of the staggered dynamics on a two-dimensional lattice composed of superconducting microwave resonators connected with tunable couplings. The naive generalization of the one-dimensional staggered dynamics generates two uncoupled one-dimensional quantum walks; thus more complex partitions need to be employed. However, by analyzing the coherence of the dynamics, we show that the quantumness of the evolution corresponding to two independent one-dimensional quantum walks can be... 

The discrete-time quantum walk dynamics can be generated by a time-dependent Hamiltonian, repeatedly switching between the coin and the shift generators. We change the model and consider the case where the Hamiltonian is time-independent, including both the coin and the shift terms in all times. The eigenvalues and the related Bloch vectors for the time-independent Hamiltonian are then compared with the corresponding quantities for the effective Hamiltonian generating the quantum walk dynamics. Restricted to the non-localized initial quantum walk states, we optimize the parameters in the time-independent Hamiltonian such that it generates a dynamics similar to the Hadamard quantum walk. We... 

In this paper the fault-Tolerant control problem for uncertain linear systems in the presence of L, disturbances and actuator saturation is studied. The conflict between enlarging the domain of attraction and attenuating the effect of L, disturbances is tackled by proposing a non-constant state feedback controller. The feedback gains are calculated off-line by using linear matrix inequalities. In addition, the proposed method is capable of tolerating time-varying faults. The suggested approach is implemented on a sample model and the result is compared with other works  

This paper presents a novel fault-tolerant control strategy to compensate the time-varying loss of actuators’ effectiveness. It considers intermediate situations where the fault is not determined precisely (unlike active approaches) but overall estimations about its rate and final value are available through the previous experiences and/or experiments. Based on the estimations, two upper and lower time-varying bounds on the actuators’ effectiveness are established to be exploited in the procedure of controller design. In a special case, where these bounds are constant, the method will be reduced to the conventional passive approach. Also, actuator saturation and the effects of (Formula... 

This paper presents a unified passive–active fault-tolerant control strategy to compensate the loss of actuators’ effectiveness. The proposed approach is capable of handling the system in pre- and post-fault diagnosis intervals by passive and active approaches, respectively. The stability of the designed system is independent of the accuracy of information provided by the fault detection and diagnosis unit, however, a precise estimation could improve the conservation. Actuator saturation and L ∞ disturbances effects are considered in the design stage. The trade-off between maximising the domain of attraction and minimising the effects of L ∞ disturbances is tackled by developing a... 

This paper presents a unified passive–active fault-tolerant control strategy to compensate the loss of actuators’ effectiveness. The proposed approach is capable of handling the system in pre- and post-fault diagnosis intervals by passive and active approaches, respectively. The stability of the designed system is independent of the accuracy of information provided by the fault detection and diagnosis unit, however, a precise estimation could improve the conservation. Actuator saturation and L∞ disturbances effects are considered in the design stage. The trade-off between maximising the domain of attraction and minimising the effects of L∞ disturbances is tackled by developing a non-constant... 

CaO derived from calcined eggshell was doped with Na–K by wet impregnation method and the effect of different Na/K molar ratios was investigated on biodiesel production from canola oil. The catalysts were characterized by X-ray Powder Diffraction (XRD), Brunauer–Emmett–Teller (BET), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray (EDX), and Thermogravimetric (TGA) analyses. FAME yields were determined by Gas Chromatography-Mass Spectrometry (GC-MS). The Na–K/CaO catalyst with Na/K molar ratio of 1 showed the highest FAME yield of 97.6% at optimum reaction conditions. Structural investigation of materials revealed that FAME yield was proportional to the number of basic sites on... 

This paper presents a new experimental-numerical method for deriving the transfer functions of a half-automobile model, containing: chassis, body, engine, engine mount and steering wheel, with five degrees of freedom. In this method different parts of system are not required to be disassembled from the main system and the transfer functions of subsystem are obtained through testing of the whole system. This method is based on the experimental results and does not need a mathematical model of the half-automobile. In this method, transfer functions of various parts of chassis are calculated through obtaining the response of secondary elements mounted on the chassis to the displacement input... 

The insect circulatory system contains an open hemocoel, in which the mechanism of hemolymph flow control is ambiguous. As a continuous fluidic structure, this cavity should exhibit pressure changes that propagate quickly. Narrow-waisted insects create sustained pressure differences across segments, but their constricted waist provides an evident mechanism for compartmentalization. Insects with no obvious constrictions between segments may be capable of functionally compartmentalizing the body, which could explain complex hemolymph flows. Here, we test the hypothesis of functional compartmentalization by measuring pressures in a beetle and recording abdominal movements. We found that the... 

In [1], [2] it is shown that the minimum broadcast rate of a linear index code over a finite field Fq is equal to an algebraic invariant of the underlying digraph, called minrankq. In [3], it is proved that for F2 and any positive integer k, minrankq(G) ≤ k if and only if there exists a homomorphism from the complement of the graph G to the complement of a particular undirected graph family called 'graph family {Gk}'. As observed in [2], by combining these two results one can relate the linear index coding problem of undirected graphs to the graph homomorphism problem. In [4], a direct connection between linear index coding problem and graph homomorphism problem is introduced. In contrast to... 

I present an in-depth review of the trends and the directions taken by researchers worldwide in optical code-division multiple-access (OCDMA) systems. I highlight those trends and features that I believe are essential to the successful introduction of various OCDMA techniques in communication systems and data networks in the near future. In particular I begin by giving a comprehensive review of the construction of optical orthogonal codes (OOCs). Specifically I discuss the recently developed algorithms that are based on matrix algebra, which simplify and enhance the efficiencies of algorithms in OOC generation. In communication systems studies I first focus on and discuss various OCDMA... 

In this paper, we analyze the worst-case delay performance of a network of fair queuing servers in case of multiple-paths between source-destination pairs. In order to develop worst-case delay analysis for the multiple-path scenario, two challenging events should be addressed: merging different sub-streams of a session as well as distributing a traffic stream among different paths (traffic partitioning). Specifically, we propose to merge incoming sub-streams of a session to a node according to a limited rate Fair Queuing (FQ) scheme. Although the merged stream is treated as a unity, this approach results in a guaranteed level of service to each sub-stream. In addition, an algorithm is... 

This paper presents an investigation of the effects of tool rake angle and nose radius on the surface quality of ultraprecision diamond-turned porous silicon. The results showed that as rake angle decreases, the high-stress field induced by the tool edge increases, causing microcracks to propagate extensively near the pore walls. As a result, the ductile-machined areas shrank under a negative tool rake angle. On the other hand, brittle fracture occurred around pores released cutting pressure significantly. These trends of rake angle effects are distinctly different from those in the cutting of non-porous silicon. Finite element simulation of stress in the cutting area agreed with the... 

This paper presents an investigation of the effects of tool rake angle and nose radius on the surface quality of ultraprecision diamond-turned porous silicon. The results showed that as rake angle decreases, the high-stress field induced by the tool edge increases, causing microcracks to propagate extensively near the pore walls. As a result, the ductile-machined areas shrank under a negative tool rake angle. On the other hand, brittle fracture occurred around pores released cutting pressure significantly. These trends of rake angle effects are distinctly different from those in the cutting of non-porous silicon. Finite element simulation of stress in the cutting area agreed with the...