Sharif Digital Repository

Let G be a group. The intersection graph of G, denoted by Γ(G), is the graph whose vertex set is the set of all nontrivial proper subgroups of G and two distinct vertices H and K are adjacent if and only if H ∩ K ≠= 1. In this paper, we show that the girth of Γ(G) is contained in the set {3,∞ }. We characterize all solvable groups whose intersection graphs are triangle-free. Moreover, we show that if G is finite and Γ (G) is triangle-free, then G is solvable. Also, we prove that if Γ (G) is a triangle-free graph, then it is a disjoint union of some stars. Among other results, we classify all abelian groups whose intersection graphs are complete. Finally, we study the intersection graphs of... 

Let R be a ring with identity and M be a unitary left R-module. The complement of the intersection graph of submodules of M, denoted by Γ(M), is defined to be a graph whose vertices are in one-to-one correspondence with all nontrivial submodules of M and two distinct vertices are adjacent if and only if the corresponding submodules of M have zero intersection. In this paper, we consider the complement of the intersection graph of submodules of a module. We prove that, if Γ(M) is connected and Δ(Γ(M)) < ∞, then M is semisimple, where Δ(Γ(M)) is the maximum degree of Γ(M). We show that, if Γ(M) is a forest, then each component of Γ(M) is a star graph. Moreover, it is proved that, if Γ(M) is a... 

Free vibration response of a cylindrical shell closed with two hemispherical caps at the ends (hermit capsule) is analysed in this research. It is assumed that the system of joined shell is made from functionally graded materials (FGM). Properties of the shells are assumed to be graded through the thickness. Cylindrical and hemispherical shells are unified in thickness. To capture the effects of through-the-thickness shear deformations and rotary inertias, first order theory of shells is used. Donnell type of kinematic assumptions are adopted to establish the general equations of motion and the associated boundary and continuity conditions with the aid of Hamilton's principle. The resulting... 

Let Δ be a simplicial complex and χ be an s-coloring of Δ. Biermann and Van Tuyl have introduced the simplicial complex Δχ. As a corollary of Theorems 5 and 7 in their 2013 article, we obtain that the Stanley–Reisner ring of Δχ over a field is Cohen–Macaulay. In this note, we generalize this corollary by proving that the Stanley–Reisner ideal of Δχ over a field is set-theoretic complete intersection. This also generalizes a result of Macchia  

In this paper, we present a concretely efficient protocol for private set intersection (PSI) in the multi-party setting using oblivious pseudorandom function (OPRF). In fact, we generalize the approach used in the work of Chase and Miao [CRYPTO 2020] towards deploying a lightweight multi-point OPRF construction for two-party PSI. Our protocol only includes oblivious transfer (OT) extension and garbled Bloom filter as its main ingredients and avoids computationally expensive operations. From a communication pattern perspective, the protocol consists of two types of interactions. The first type is performed over a star-like communication graph in which one designated party interacts with all... 

This paper presents a new analytical model for calculating the cutter-workpiece engagement (CWE) boundaries in the ball-end finish milling process of curved surfaces. To this end, first, a quadratic mathematical representation considering the principal curvatures of the surface is employed to locally describe the workpiece surface around the instantaneous cutting region. This description, then, is utilized to find the intersection curves of the tool rotary and workpiece surfaces in three ball-end milling modes including slotting, first cutting, and following cutting. Through comparison studies, the model predictions are verified by the corresponding results obtained via solid modeling in... 

Free vibration response of a joined shell system including cylindrical and spherical shells is analyzed in this research. It is assumed that the system of joined shell is made from a functionally graded material (FGM). Properties of the shells are assumed to be graded through the thickness. Both shells are unified in thickness. To capture the effects of through-the-thickness shear deformations and rotary inertias, first-order shear deformation theory of shells is used. The Donnell type of kinematic assumptions is adopted to establish the general equations of motion and the associated boundary and continuity conditions with the aid of Hamilton’s principle. The resulting system of equations is... 

We study here the algorithmic analysis of systems modeled in terms of availability languages. Our first main result is a positive answer to the emptiness problem: it is decidable whether a given availability language contains a word. The key idea is an inductive construction that replaces availability languages with Parikh-equivalent regular languages. As a second contribution, we solve the intersection problem modulo bounded languages: given availability languages and a bounded language, it is decidable whether the intersection of the former contains a word from the bounded language. We show that the problem is NP-complete. The idea is to reduce to satisfiability of existential Presburger... 

Creating laser texture on dental implants is a novel method for accelerating osseointegration and prolongation of lifespan. The purpose of this research was twofold: (1) Creating intersecting lines pattern with different angles (0°, 15°, 30°, 45°, 60°, 75°, and 90°) on the surface of Ti6Al4V, using pulse Nd:YAG laser with a wavelength of 1064 nm and a pulse length of 170 ns and (2) comparing optical and SEM images, EDS analyses, contact angles (CAs), and surface free energies (FEs) for different intersecting lines angles. CA and FE depended on the intersecting lines angle according to Y = Y 0 + A sin (x B + C), where Y is the CA or FE; x is the intersecting lines angle; and Y0, A, B, and C... 

Despite complex fluctuations, missing data, and maintenance costs of detectors, traffic volume forecasting at intersections is still a challenge. Moreover, most existing forecasting methods consider an isolated intersection instead of multiple adjacent ones. By accurately forecasting the volume of short-term traffic, a low-cost method can be provided to solve the problems of congestion, delay, and breakdown of detectors in the road transport system. This paper outlines a novel hybrid method based on deep learning to estimate short-term traffic volume at three adjacent intersections. The gated recurrent unit (GRU) and long short-term memory (LSTM) bilayer network with wavelet transform (WL)... 

Analyzing motion patterns in traffic videos can be employed directly to generate high-level descriptions of their content. For traffic videos captured from intersections, usually, we can easily provide additional information about traffic phases. Such information can be obtained directly from the traffic lights or through traffic lights controllers. In this paper, we focus on incorporating additional information to analyze the traffic videos more efficiently. Using side information on traffic phases, the semantic of motion patterns from traffic intersection scenes can be learned more effectively. The learning is performed based on optical flow features extracted from training video clips,... 

High-voltage power supplies (HVPSs) are widely used to drive vacuum tubes, inherently susceptible to vacuum arc faults. Owing to the considerable cost of vacuum tubes, the HVPS should enjoy a reliable, fast protection mechanism. A common protection mechanism against vacuum arc faults is the shunt crowbar. The crowbar diverts the energy stored in the elements of the HVPS through itself as a parallel path, thereby protecting vacuum tubes from irrecoverable damages. Among all types of the shunt crowbar, the thyristor-based crowbar along with the fault current limiter (FCL) resistors attracts more attention because of its more reliable operation. The absence of the comprehensive design procedure... 

In this letter, a new notion of stability is introduced, which is called triangular stability. A system is called triangularly stable if the norm of its state vector is bounded by a decreasing linear function of time such that its intersection point with the time axis can be arbitrarily commanded by the user. Triangular stability implies prescribed-time stability, which means that the nonlinear system is converged to zero equilibrium at an arbitrary finite time. A prescribed-time controller with guaranteed triangular stability is developed for normal form nonlinear systems with uncertain input gain, which is able to reject the disturbances and unmodeled dynamics. Numerical simulations are... 

In this paper we deal with ray tracing acceleration problem in wave propagation simulation as a separate problem from its computer graphical counterpart and try to review accelerating techniques with this point of view. We build a classical kd-tree adapted to the special geometry of the problem. Then we mention the main differences between these two problems and devise algorithms that use these differences for accelerating intersection test in this problem even further  

Human error is one of the leading causes of accidents. Distraction, fatigue, poor visibility, speeding, and other such errors made by drivers can cause accidents. With the rapid advancements in automation technologies, transportation planners have strived to use Intelligent Transportation Systems (ITS) to minimize human error. In this study, the effect of Autonomous Vehicles (AVs) on the number of potential conflicts at two unsignalized intersections is investigated by using a microsimulation model in PTV Vissim software. For human-driven cars, the factor that is considered for calibration is driver distraction mainly caused by reading or writing text messages on a cellphone while driving.... 

Due to their different sizes and operational characteristics, vehicles other than passenger cars have a different influence on traffic operations especially at intersections. The passenger car equivalent (PCE) is the parameter that shows how many passenger cars must be substituted for a specific heavy vehicle to represent its influence on traffic operation. PCE is commonly estimated using headway-based methods that consider the excess headway utilized by heavy vehicles. In this research, the PCE was estimated based on the delay parameter at three signalized intersections in Tehran, Iran. The data collected were traffic volume, travel time for each movement, signalization, and geometric... 

This study involves the capability of severe shot peening (SSP) as a catalyst intake for plasma nitriding process and the probability of reducing the requirement of thermal energy individually on the diffusion of interstitial atoms. To this end, combination of mechanical-thermal energy is run with pure thermal plasma assisted energy. Therefore, SSP is exposed to AISI 304 austenitic stainless steel as a former treatment and gradient structured surface (nanograined zone, ultrafine grain martensite-twin intersections zone and twin densed zone) is created. Then, plasma nitriding at 400 0 C-4h and 475 0 C-2h temperature-duration conditions. The condition of 475 0 C-2h provides the requirements of... 

Private set intersection (PSI) is a fundamental cryptographic protocol which has a wide range of applications. It enables two clients to compute the intersection of their private datasets without revealing non-matching elements. The advent of cloud computing drives the ambition to reduce computation and data management overhead by outsourcing such computations. However, since the cloud is not trustworthy, some cryptographic methods should be applied to maintain the confidentiality of datasets. But, in doing so, data owners may be excluded from access control on their outsourced datasets. Therefore, to control access rights and to interact with authorized users, they have to be online during... 

The studies surrounding the concept of microdroplets have seen a dramatic increase in recent years. Microdroplets have applications in different fields such as chemical synthesis, biology, separation processes and micro-pumps. This study numerically investigates the effect of different parameters such as Capillary number, Length of droplets, and Magnetic Bond number on the splitting process of ferrofluid microdroplets in symmetric T-junctions using an asymmetric magnetic field. The use of said field that is applied asymmetrically to the T-junction center helps us control the splitting of ferrofluid microdroplets. During the process of numerical simulation, a magnetic field with various...