Sharif Digital Repository

Chip multiprocessors (CMPs) issue write invalidations (WIs) to assure program correctness. In conventional snoop-based protocols, writers broadcast invalidations to all nodes as soon as possible. In this work we show that this approach, while protecting correctness, is inefficient due to two reasons. First, many of the invalidated blocks are not accessed after invalidation making the invalidation unnecessary. Second, among the invalidated blocks many are not accessed anytime soon, making immediate invalidation unnecessary. While invalidating the first group could be avoided altogether, the second group's invalidation could be delayed without any performance or correctness cost. Accordingly,... 

In this report we outline the study of the development of calorimeter detectors using bright scintillating crystals. We discuss how timing information with a precision of a few tens of pico seconds and below can significantly improve the reconstruction of the physics events under challenging high pileup conditions to be faced at the High-Luminosity LHC or a future hadron collider. The particular challenge in measuring the time of arrival of a high energy photon lies in the stochastic component of the distance of initial conversion and the size of the electromagnetic shower. We present studies and measurements from test beams for calorimeter based timing measurements to explore the ultimate... 

Aims. We present V and R photometry of the gravitationally lensed quasars WFI 2033-4723 and HE 0047-1756. The data were taken by the MiNDSTEp collaboration with the 1.54 m Danish telescope at the ESO La Silla observatory from 2008 to 2012. Methods. Differential photometry has been carried out using the image subtraction method as implemented in the HOTPAnTS package, additionally using GALFIT for quasar photometry. Results. The quasar WFI 2033-4723 showed brightness variations of order 0.5 mag in V and R during the campaign. The two lensed components of quasar HE 0047-1756 varied by 0.2-0.3 mag within five years. We provide, for the first time, an estimate of the time delay of component B... 

This study presents a new approach to decompose singular time-delay systems (STDSs) in a way that they can be transformable to normal time-delay systems (TDSs) with a lower order. Necessary and sufficient conditions are provided to determine which STDSs can be transformed to TDSs. Also, a stabilisation method is provided to stabilise the system, while the time delay in the system can belong to several distinct intervals or even everywhere. The proposed method is non-fragile towards controller parameters. This method also reveals one of the many applicable situations of the proposed decomposition. The effectiveness of the proposed method is illustrated through some examples. © 2018 The... 

The equivalent circuit approach (ECA) is used in this work to analyze and design a previously proposed one-dimensional planar blazed grating of the resonant type. The analysis covers both the classical Littrow configuration, when the direction of the relevant diffracted order coincides with that of the incident wave (Bragg blazing), and when these directions are different (off-Bragg blazing). Once the scattering problem of the grating structure is posed as a discontinuity problem inside an equivalent generalized waveguide (corresponding to the unit cell of the original structure) and studied in terms of its equivalent circuit network, the possibility of transferring all the power of the... 

As contemporary digital systems specifically embedded systems become more and more complex, taking advantage of system-level design is being more widespread. Many embedded systems must operate under strict timing constraints. One of the best methods for examining timing constraints in an embedded system can be done via the performance verification. In this paper an assertion-based verification methodology has been proposed for verifying system-level timing constraints in an embedded system. Performance assertions are specified by an assertion language at the transaction-level of abstraction. A Turing machine and a structure named performance evaluator have been coupled to provide a... 

We present an LC circuit model that supports a tilted “Dirac cone” in its spectrum. The tilt of the Dirac cone is specified by the parameters of the model consisting of mutual inductance between the neighboring sites and a capacitance C0 at every lattice site. These parameters can be completely measured by impedance spectroscopy. Given that a tilted Dirac cone can be described by a background spacetime metric, the impedance spectroscopy can perfectly provide (local) information about the metric of the spacetime. Nonuniform spatial dependence of the mutual inductance or capacitance induces a nontrivial geometrical structure on the emergent spacetime. Our work extends the range of usefulness... 

In this paper, we propose a very fast and accurate analytical approach to estimate the overall SER and to identify the most vulnerable gates,flip-flops, and paths of a circuit. Using such information, designers can selectively protect the vulnerable parts resulting in lower power and area overheads that are the most important factors in embedded systems. Unlike previous approaches, the proposed approach firstly does not rely on fault injection or fault simulation; secondly it measures the SER for multi cycles of circuit operation; thirdly, the proposed approach accurately computes all three masking factors, namely, logical, electrical, and timing masking; fourthly, the effects of error... 

The scattering of graphene surface plasmons normally incident on a line discontinuity in graphene surface conductivity is investigated. The effect of the length of the transition region on the reflection and transmission coefficients is studied. It is shown that the reflection coefficient is reduced by widening the transition region. Based on the results obtained, a transmission line model is derived for the graphene sheet in which the discontinuity is represented by a simple circuit. This model is next used to design graphene-based bandpass and bandstop filters with arbitrary bandwidth in the terahertz regime  

This paper addresses the design of an observer based adaptive neural controller for a class of strict-feedback nonlinear uncertain systems subject to input delay, saturation and unknown direction. The input delay has been handled using an integral compensator term in the controller design. A neural network observer has been developed to estimate the unmeasured states. In the observer design, the Lipschitz condition has been relaxed. To solve the problem of unknown control directions, the Nussbaum gain function has been applied in the backstepping controller design. “The explosion of complexity” occurred in the traditional backstepping technique has been avoided utilizing the dynamic surface... 

A compact aging model for circuit simulation has been developed by considering all possible trapped carriers within MOSFETs. The hot carrier effect and the N(P)BTI effect are modeled by integrating the substrate current as well as the oxide field change due to the trapped carriers. Additionally, the carriers trapped within the highly resistive drift region are included for high-voltage (HV)-MOSFET modeling. The aging model considers the dynamic trap-density increase as a function of circuit-operation time with dynamically varying stress conditions for each individual MOSFET. A self-consistent solution is obtained by iteratively solving the Poisson equation including the trap density. The... 

The reported investigation aims at developing a compact model for circuit-aging simulation. The model considers dynamic trap-density increase during circuit operation in a consistent way. The model has been applied to an SRAM cell, where it is believed that the NBTI effect dominates. Our simulation verifies that the hot-carrier effect has a compensating influence on the NBTI aging of SRAM cells. © 2017 The Japan Society of Applied Physics  

3D imaging technologies are applied in numerous areas, including self-driving cars, drones, and robots, and in advanced industrial, medical, scientific, and consumer applications. 3D imaging is usually accomplished by finding the distance to multiple points on an object or in a scene, and then creating a point cloud of those range measurements. Different methods can be used for the ranging. Some of these methods, such as stereovision, rely on processing 2D images. Other techniques estimate the distance more directly by measuring the round-trip delay of an ultrasonic or electromagnetic wave to the object. Ultrasonic waves suffer large losses in air and cannot reach distances beyond a few... 

In this paper, the short-circuit fault in three-phase quasi-Z-source inverter (q-ZSI) is analyzed and a linear model is proposed for the short-circuit analysis. The proposed model is based on the state space equations of the system. By using this model, the most critical situation during short-circuit fault is recognized; the maximum reaction time for the protection system could be estimated and elements that are prone to failure are identified as well. The analysis is categorized into two groups, leg fault and switch fault. The linear model is confirmed by simulation of 1kw three-phase q-ZSI. © 2017 IEEE  

Security in mobile handsets of telecommunication standards such as GSM, Project 25 and TETRA is very important, especially when governments and military forces use handsets and telecommunication devices. Although telecommunication could be quite secure by using encryption, coding, tunneling and exclusive channel, attackers create new ways to bypass them without the knowledge of the legitimate user. In this paper we introduce a new, simple and economical circuit to warn the user in cases where the message is not encrypted because of manipulation by attackers or accidental damage. This circuit not only consumes very low power but also is created to sustain telecommunication devices in aspect... 

Interfering electromagnetic energy could be a very powerful pulse which is generated and incident onto communication system such as linear wire antenna through direct radiation. In this paper, the transient responses of the linear wire antenna such as dipole antenna under the impact of the early-time (E1) high-altitude electromagnetic pulse (HEMP) are investigated using the equivalent circuit due to a primary element used in the modeling of systems for HEMP vulnerability is the linear wire antenna such as dipole antenna. Based on the equivalence concept of HEMP radiation source and linear wire antennas, the response at receiving antenna port is calculated efficiently with an uncomplicated... 

It is shown that a compact MOSFET-aging model for circuit simulation is possible by considering the dynamic trap-density increase, which is induced during circuit operation. The dynamic trap/detrap phenomenon, which influences the switching performance, is also considered on the basis of well-known previous results. Stress-dependent hot-carrier effect and NBTI effect, origins of the device aging, are modeled during the circuit simulation for each device by integrating the substrate current as well as by determining the oxide-field change due to the trapped carriers over the individual stress-duration periods. A self-consistent solution can be obtained only by iteratively solving the Poisson... 

High frequency transformer is an important component in lots of modern power electronic circuits. In order to analyze the behavior of these transformers, equivalent circuit models containing parasitic elements have been proposed. But most of them are complicated and not appropriate to use in processes in which high speed analysis is crucial. In this paper, a second-order simplified model for high frequency transformers is obtained. Besides, the frequency ranges in which the proposed model has enough precision, are calculated and examined. To validate the simplified circuit model, some simulations are carried out. During the simulation, the effects of transformer equivalent circuit parameters... 

An online operator position prediction approach based on artificial neural network for teleoperation systems is proposed in this paper, which predicts future position of operator's hand based on current available data. The neural network gathers inputs for some time at the beginning of the operation, then is trained, and is finally exploited through the rest of the operation. Superiority of the proposed approach can be investigated from two aspects. Firstly, no limiting assumption is required in this approach in contrast with the proposed methods in the literature. Secondly, unknown operator intention can be dealt with in real time if it is not too sudden and unpredictable. Two different... 

This paper presents a tunable reflection/transmission coefficient (TRTC) circuit based on a 45° hybrid coupler that is potentially useful for leakage cancelation purposes. The analysis of the proposed TRTC circuit shows that the circuit can cover any reflection/transmission coefficient of less than 0.5 on the Smith chart by adjusting only two variable resistors. Meanwhile, the real and imaginary parts of the reflection/transmission coefficient can be tuned independently, facilitating the use of this circuit in feedback systems. To implement the 45° hybrid coupler used in the proposed TRTC circuit, a new wideband planar topology for arbitrary phase and amplitude hybrid coupler is introduced....