Sharif Digital Repository

Geotechnical design codes have been shifted from classical limit equilibrium analysis toward the performance-based procedures. In foundation design, settlement is the most representative parameter for its performance. Settlement of shallow foundations subjected to earthquake loading and its consequences is one of the most outstanding issues which should be considered in designing different structures. In this study, settlement of shallow footing on two-layered subsoil strata under earthquake loading is of concern. The numerical study presented in this research by means of a 3D dynamic fully coupled u-p analysis, addresses the effect of different parameters on shallow foundation settlement... 

Short-circuit fault (SCF) detection is mandatory in a high voltage DC power supply (HVPS) to prevent fatal damage. The majority of converters employ a single sensor to detect the SCF. This attribute increases the interference vulnerability of the fault detection (FD) system in the presence of noise. Therefore, miss detections and false alarms are possible to occur. Miss detections and false alarms are harmful catastrophes in most applications. A commonly used method to suppress the noise impacts is using a low-bandwidth low-pass filter. However, the use of the low-bandwidth low-pass filter reduces the speed of FD due to the filter delay. This paper proposes a fast FD algorithm based on... 

Vacuum arc is one of the most important failure factors of the vacuum tubes. The amount of delivered energy from the high-voltage dc power supply to the vacuum tube is an important issue during the vacuum arc in the tube. Vacuum arc acts as a short-circuit fault (SCF) at the power supply output. The majority of converters use a single current sensor to measure only the converter output current for detecting the SCF. However, the sensor may provide unreliable data because of the noise effect. Application of a low-pass filter reduces the noise effect. Regarding the delay of the low-pass filter, the interval of arc detection increases and more energy is delivered to the tube. In this article, a... 

Vacuum arc is one of the most important failure factors of the vacuum tubes. The amount of delivered energy from the high-voltage dc power supply to the vacuum tube is an important issue during the vacuum arc in the tube. Vacuum arc acts as a short-circuit fault (SCF) at the power supply output. The majority of converters use a single current sensor to measure only the converter output current for detecting the SCF. However, the sensor may provide unreliable data because of the noise effect. Application of a low-pass filter reduces the noise effect. Regarding the delay of the low-pass filter, the interval of arc detection increases and more energy is delivered to the tube. In this article, a... 

In performance-based geotechnical earthquake engineering, the required degree and spatial extent of ground densification for mitigation of liquefaction beneath a structure should be determined based on the acceptable levels of performance of foundation. Currently, there is no solution for evaluation of the amount of settlement and tilt of footings constructed on a densified ground which is surrounded by a liquefiable soil. This implies the need for numerical procedures for simulation of seismic behavior of shallow foundations supported on both liquefiable and densified subsoil. In this paper, the dynamic response of shallow foundations on a densified ground is studied using a 3D fully... 

Vacuum tubes are widely used for various applications. These vacuum tubes are supplied by high voltage power supplies. The amount of delivered energy from the high voltage power supply to the vacuum tube is an important issue during the vacuum arc in the tube. The protection mechanism consists of a shunt crowbar which diverts the fault current from the tube to itself as a parallel path. Detection of the vacuum arc is crucial and only one sensor is usually employed to detect the vacuum arc. This characteristic intensifies the interference susceptibility of the vacuum arc diagnosis system in a noisy environment. As a result of the noise, the arc detection system can report false alarms. False... 

Liquefaction is a phenomenon through which saturated sandy soil loses its shear strength and turns into a liquefied state. One of the most detrimental consequences of liquefaction is the reconsolidation volumetric settlements after the earthquakes, which is due to the dissipation of excess pore pressure caused by earthquakes. Severe floods can follow these settlements in free fields such as grounds close to the sea or rivers. Several researchers studied this phenomenon using data obtained from experiments in the lab or observations in the fields. Previous works were mainly based on a limited number of experimental observations and considered loadings and boundary conditions that were... 

In our previous report (J. Phys. Org. Chem., 2017), we discussed the dual behavior of gold nanocluster (Au3 NC), where it scavenged reactive oxygen species (ROS) while promoted their generation to a lesser extent. Continuing this quest, we investigate the effects of Au3 NC on common reactive nitrogen species (RNS: O=N˙ and O=N-O) and their precursors (O=N-H and O=N-O-H, respectively), at B3LYP/LACVP+* level of theory. We compare the results with those of prevalent ROS (H-O˙ and H-O-O˙) and their precursors (H-O-H and H-O-O-H, respectively). To this end, various parameters are probed such as binding energy (Eb), bond dissociation energy (BDE), bond lengths, Mullikan spin density (MSD),... 

This paper is aimed at investigating some computational aspects of different isoperimetric problems on weighted trees. In this regard, we consider different connectivity parameters called minimum normalized cuts/isoperimetric numbers defined through taking the minimum of the maximum or the mean of the normalized outgoing flows from a set of subdomains of vertices, where these subdomains constitute a partition/subpartition. We show that the decision problem for the case of taking k-partitions and the maximum (called the max normalized cut problem NCP^M), and the other two decision problems for the mean version (referred to as IPP^m and NCP^m) are NP-complete problems for weighted trees. On... 

We have investigated the pathways of stability for NHCs derived from azole, di-azole, n-tetrazole, and ab-tetrazole (1a, 2a, 3a, and 4a, respectively), at the M06/6-311++G** level of theory. Optimization and vibrational frequency calculations of ground states (GS) and transition states (TS) are performed to identify Gibbs free energies and nature of stationary points, respectively. Two possible pathways of stability for 1a-4a are compared and contrasted which entail dimerization through hydrogen bonding (HB) and covalent bonding (CB). The CB pathway comprises head to head (HH) and head to tail (HT) dimerizations. Plausible reaction profiles are illustrated for 1a-4a along with the mechanism... 

In our previous report (J. Phys. Org. Chem., 2017), we discussed the dual behavior of gold nanocluster (Au3 NC), where it scavenged reactive oxygen species (ROS) while promoted their generation to a lesser extent. Continuing this quest, we investigate the effects of Au3 NC on common reactive nitrogen species (RNS: O=N˙ and O=N-O) and their precursors (O=N-H and O=N-O-H, respectively), at B3LYP/LACVP+* level of theory. We compare the results with those of prevalent ROS (H-O˙ and H-O-O˙) and their precursors (H-O-H and H-O-O-H, respectively). To this end, various parameters are probed such as binding energy (Eb), bond dissociation energy (BDE), bond lengths, Mullikan spin density (MSD),... 

Let LL be a reversible Markovian generator on a finite set View the MathML sourceV. Relations between the spectral decomposition of LL and subpartitions of the state space View the MathML sourceV into a given number of components which are optimal with respect to min–max or max–min Dirichlet connectivity criteria are investigated. Links are made with higher-order Cheeger inequalities and with a generic characterization of subpartitions given by the nodal domains of an eigenfunction. These considerations are applied to generators whose positive rates are supported by the edges of a discrete cycle ZNZN, to obtain a full description of their spectra and of the shapes of their eigenfunctions, as... 

In this paper1 we consider higher isoperimetric numbers of a (finite directed) graph. In this regard we focus on the nth mean isoperimetric constant of a directed graph as the minimum of the mean outgoing normalized flows from a given set of n disjoint subsets of the vertex set of the graph. We show that the second mean isoperimetric constant in this general setting, coincides with (the mean version of) the classical Cheeger constant of the graph, while for the rest of the spectrum we show that there is a fundamental difference between the nth isoperimetric constant and the number obtained by taking the minimum over all n-partitions. In this direction, we show that our definition is the...