Narrow Results

The effect of the damaged car evacuation on the traffic flow behavior is investigated, in the one-dimensional deterministic Nagel–Schreckenberg model, using parallel dynamics. A realistic model applied to the cars involved in collisions is considered. Indeed, in this model we suppose that the damaged cars must be removed from the ring with a probability P_exit. This investigation enables us to understand how the combination of the two probabilities, namely P_col and P_exit, acts on density and current. It is found that the current and density at the steady state, depend strongly on the initial density of cars in the ring. However, for the intermediate initial density ρ_i, the current J decreases when increasing either P_exit and/or P_col. While, for high initial density, J increases passes through a maximum and decreases for large values of P_exit. Furthermore, the current can decrease or increase with the collision probability depending on the initial density.

We numerically study the evolution of a boost-invariant SYM medium using AdS/CFT. We consider a toy model for the collision of gravitational shock waves, finding that the energy density first increases, reaches a maximum and then starts to decrease, matching hydrodynamics for late times. For the initial conditions we consider, the hydrodynamic scale governing the late time behavior is to very good approximation determined by the area of the black hole horizon at initial times. Our results provide a toy model for the early time evolution of the bulk system in heavy-ion collisions at RHIC and the LHC.

Hydrodynamic migration of spherical slippery particles suspended in a cylindrical channel flow is numerically studied in this paper. The effects of the particle concentration of particle ($\varphi )$, tube-to-particle diameter ratio ($D∕a)$ and Knudsen number (Kn), respectively, with ranges of $0.0129<\varphi <0.217,4<D∕a<12$ and $0<\mathrm{\text{Kn}}<0.1$ with the channel Reynolds number of $38<\mathrm{\text{Re}}<950$, are concerned in the simulations. The objective of this work is to explore the pipeline transportation of relatively large and moderately dense particles with slippery surface, for which the characteristics have not been comprehensively exhibited in the literature. Such particle-resolved suspension flow is solved by a three-dimensional lattice Boltzmann method, where a curved kinetic boundary condition is adopted to resolve the velocity slip phenomenon at the fluid-particle interface, and the particle-particle collision is performed by a repulsive force model. The results elucidate that the effect of particle focusing is less marked at intermediate concentrations. At larger $\varphi$, some particles may migrate to the center of channel due to the aggravation of the mutual collision. The increase of Re contributes to the particle focusing at low $\varphi$, but not for the case of higher $\varphi$. On the other hand, the $D∕a$ generally has a negative effect on the inertial focusing. Furthermore, the migration velocity of particles reduces and the behavior of inertial focusing is enhanced simultaneously, with the increase of Kn.

We study the phenomena associated with the low-velocity impact of two solid discs of equal size using a cell model of brittle solids. The fragment ejection exhibits a jet-like structure the direction of which depends on the impact parameter. We obtain the velocity and the mass distribution of the debris. Varying the radius and the initial velocity of the colliding particles, the velocity components of the fragments show anomalous scaling. The mass distribution follows a power law in the region of intermediate masses.

A method of constructing a quantum hash function (QHF) based on continuous-time quantum walk is proposed, in which the time of quantum walk is controlled by the binary string message, namely, a binary string message as the input of the constructed QHF and the probability value of finally walking to the nodes on the cycle is used as the output of the QHF. Numerical simulation and performance analysis show that our QHF has obvious advantages in the efficiency of the QHF compared with the existing QHF based on the discrete-time quantum walk, that is, the efficiency of our scheme is nearly 4 times faster in computing the hash value of the same size file compared with the most efficient scheme. Besides, the QHF has also better collision resistance compared with the existing QHF based on the discrete-time quantum walk.

Structure bodies and surrounding soils in certain types of bridges and tunnels may be prone to collisions during earthquake. A dynamic system composed of discrete and finite elements is developed using explicit formulation for equations of motion, and nonlinearities in soils and at interfaces of disjoined regions are implemented. Time history solutions are carried out to examine the plastic deformation in soils as well as the integrity of structures. Two case studies are presented in which collisions among disjoined regions are anticipated in the event of extremely large earthquakes. Case one is based on a replica from a quake-stricken bridge, to illustrate that a backfill with moderate soil strength may be used as an energy-dissipating buffer to contain the shaken loose decks. The other case involves an underground subway station box with slurry walls alongside, to exemplify the seismic resistance of the dual-wall system.

Drillstring is the most important tool in petroleum drilling engineering. Alternating stress has been found to be responsible for the premature failure of drillstring. Propagation of stress wave, induced by collision between tool-joints of drillstring and borehole wall, is studied in this paper. The condition that all the tool-joints of drill pipes (DPs) strike borehole wall at the same time has been considered. Because of symmetry, the middle cross section of the DP is simplified as fixed end, and mechanical model is established as the beam with both ends fixed. Propagation of lateral displacement wave and stress wave in the DP is investigated by means of Eigen-frequency method and the Finite Element Analysis software ANSYS. The theoretic results coincide with those obtained from numerical modeling very well and also explain the drillstring accidents in gas fields.

In this paper, a semi-empirical molecular dynamics model is developed. The central collisions of C₆₀ + C₆₀ and X@C₆₀ + X@C₆₀ (X = He, Ne, Ar) at various incident energy are investigated within this model. The fullerene dimers like a "dumbbell" can be formed by a self-assembly of C₆₀ fullerene and X@C₆₀ (X = He, Ne) endohedral fullerenes, and the new fullerene structure like "peanut" can be formed by a self-assembly of Ar@C₆₀. It is found that Ar atom plays a great role in the collision of Ar@C₆₀ + Ar@C₆₀ because of its size effect. The energy effect is found that various incident energies cannot change the final structure at low energies if they are below a certain energy.

In software product line engineering (SPLE), many studies have been conducted on commonality- and variability-based feature extraction methods and on the reasoning and refinement of feature models (FMs), aiming to enhance the appropriateness and reusability of the constructed FMs in compliance with feature-oriented development. The existing methods, however, failed to assure the developed applications that contain ambiguities between the features generated in FMs by analyzers' intuitions, and hindered the reuse of such applications. Moreover, the accuracy measurements of models based on mathematics-based theoretical verification methods are difficult to apply in practice. Therefore, a refinement technique is demanded to enhance the FM accuracy.

This paper aims to identify abnormal feature duplications and collisions based on the feature attributes to address the potential ambiguities between the features in an FM generated for a target domain, and to construct more precise FMs by presenting a technique for eliminating such abnormalities. For this purpose, the profiles of the formalized attributes were first defined based on MDR. Based on the semantics and relationships between the attributes, the duplications and collisions were identified using an analysis matrix, and were generalized to formulate rules by level. Such rules were evaluated to remove the duplications and collisions. In addition, using a supporting analyzer, the features in the initial FM were registered on a repository and were analyzed for feature duplications and collisions based on the saved attribute data.

The refinements of the ambiguities between such features are likely to enable the construction of more precise application FMs and the generation of common features with higher reusability. Further, the environments using support tools are expected to provide convenience in the similarity analysis and reuse of features.

Interaction/collision of two concentric spherical thin-shells of linear fluid resulting in collapse has been considered recently. We show that addition of finely tuned electric charges on the shells apart from the cosmological constant serves to delay the collapse indefinitely, yielding an ever colliding system of two concentric fluid shells. Given the finely tuned charges, this provides an example of a perpetual two-body motion in general relativity.

Radio Frequency Identification (RFID) is promising, as a technique, to enable tracking of essential information about objects as they pass through supply chains. Information thus tracked can be utilised to efficiently operate the supply chain. Effective management of the supply chain translates to huge competitive advantage for the firms involved. Among several issues that impede seamless integration of RFID tags in a supply chain, one of the problems encountered while reading RFID tags is that of collision, which occurs when multiple tags transmit data to the same receiver slot. Data loss due to collision necessitates re-transmission of lost data. We consider this problem when Framed Slotted ALOHA protocol is used. Using machine learning, we adaptively configure the number of slots per frame to reduce the number of collisions while improving throughput.

This paper deals with the wavelet-based performance analysis of the safety barrier for use in a full-scale test. The test involves a vehicle, a Ford Fiesta, which strikes the safety barrier at a prescribed angle and speed. The vehicle speed before the collision was measured. Vehicle accelerations in three directions at the center of gravity were measured during the collision. The yaw rate was measured with a gyro meter. Using normal speed and high-speed video cameras, the behavior of the safety barrier and the test vehicle during the collision was recorded. Based upon the results obtained, the tested safety barrier has proved to satisfy the requirements for an impact severity level. By taking into account the Haar wavelets, the property of integral operational matrix is utilized to find an algebraic representation form for calculate of wavelet coefficients of acceleration signals. It is shown that Haar wavelets can construct the acceleration signals well.

Cross-sectional shapes and dimensions of concrete guardrails directly influence climbing angles and directions of a car when a collision between concrete guardrail and car occurs. At the same time, contacting and climbing angles and directions influence the peak crushing force and the peak acceleration of a car body during a collision. Therefore, cross-sectional shapes and dimensions of concrete guardrails can influence the severity of injuries sustained when a collision between concrete guardrail and car occurs. In this study, the passive safety of a car body is considered in optimizing the cross-sectional dimensions of a New Jersey (NJ) concrete guardrail based on numerical simulations and surrogate model techniques. Optimal Latin hypercube design is used to get sampling points, and multi-island genetic algorithm is utilized to obtain the optimal size of NJ concrete guardrail in the optimization process. After simulating the collision between car and optimal NJ shaped guardrail, the results show that the peak acceleration of optimal results reduces significantly by 28% compared with the initial value, and the peak interface force decreases from 378.6 kN to 241.5 kN.

Simulations of the gas fluidization of a cohesive powder were performed using the Stokesian Dynamics method and an agglomeration-deagglomeration model to investigate methods of improving the fluidizability of fine powders. Three techniques (a) high gas velocity (b) vibration-assisted fluidization and (c) tapered fluidizer were used in the simulations which provided detailed information on the bed microscopy such as the motion of 100 particles in a fluidizing vessel along with the formation and destruction of cohesive bonds during collisions. While all three techniques were found to effectively improve the fluidizability of a strongly cohesive powder, we suggest a combination of high velocity fluidization assisted by external vibration of the fluidized bed to minimize entrainment of particles.

Hubert, Mauduit and Sárközy introduced pseudorandom measures for finite pseudorandom binary lattices. Gyarmati, Mauduit, Sárközy and Stewart presented some natural and flexible constructions, which are the two-dimensional extensions and modifications of a few one-dimensional constructions. The upper estimates for the pseudorandom measures of their binary lattices are based on the principle that character sums or exponential sums in two variables can be estimated by fixing one of the variables.

In this paper, we constructed two large families of $n$ dimensional pseudorandom binary lattices by using the multiplicative inverse modulo $p$, and study the properties: pseudorandom measure, collision and avalanche effect.

This article has been retracted because it is an English translation of a Chinese paper that was published earlier, with some additional content in the later part. This is inappropriate and violates the scientific rule of anti-plagiarism. We regret that this was not detected before the article was accepted for publication in the journal.

Drillstring is the most important tool in petroleum drilling engineering. Alternating stress has been found to be responsible for the premature failure of drillstring. Propagation of stress wave, induced by collision between tool-joints of drillstring and borehole wall, is studied in this paper. The condition that all the tool-joints of drill pipes (DPs) strike borehole wall at the same time has been considered. Because of symmetry, the middle cross section of the DP is simplified as fixed end, and mechanical model is established as the beam with both ends fixed. Propagation of lateral displacement wave and stress wave in the DP is investigated by means of Eigen-frequency method and the Finite Element Analysis software ANSYS. The theoretic results coincide with those obtained from numerical modeling very well and also explain the drillstring accidents in gas fields.