Modern Physics Letters B

The traffic during rush hour in metropolises is always in heavy congestion, so the wagon trucks of logistic transportation are mostly forbidden during rush hour. In fact, quite a few logistic transportations are fulfilled by converted passenger vehicles. This paper aims to model the logistic companies’ behaviors and see through the effect of their cooperation modes on the companies and on the whole traffic conditions. The logistic companies decide their transportation pricing, warehouse using and route choosing separately or as a group (cooperation) to compete with others. It is also assumed that the heavy freight vehicles, light freight vehicles and the auto vehicles share the same network. Three models based on variational inequalities are proposed to describe the companies’ behaviors when there is no cooperation, simple cooperation and deep cooperation, respectively, and the modified diagonalization method is used to solve these models. The total transportation demand is elastic, which depends on the users’ choice of logistics company and further depends on all the companies’ prices, warehouse and route choices. The goodness of different coalitions to the companies and the whole traffic system is well investigated in the numerical examples.

Answer Scoring is defined as an act of assigning a score to an answer by a human grader. This scoring technique is costly and requires deep logical efforts and it depends on less-than-perfect human assessment. However, the Automated Scoring (AS) System has its importance in providing the student with a score as well as feedback within seconds. This paper describes an AS system in which scores are assigned to essays automatically based upon predefined algorithms. Most of the educational sectors carry out an important examination process, i.e. to examine and assess the capabilities of the student based on his/her given answers. To accomplish this process, the human graders can apply this Automated Answer Scoring system. The paper goes through the existing techniques for automated answer scoring systems and then goes on to explain the newly developed system in which scoring is done by the statistical method adopting and integrating rule-based semantic quantum-based features analysis resulting in more accuracy. It is in a way a hybrid system suitable for short answer type scoring. It also presents the methodology and architecture of AS.

We study the spin mixing dynamics of a spin-orbit coupled spin-1 Bose–Einstein condensate. Using mean-field theory and adopting plane wave solutions, the spin mixing dynamics can be well described by an internal Josephson equation. In order to establish the role of the different terms in spin mixing dynamics clearly, we consider the equilibrium state firstly, which shows that the spin-orbit coupling can significantly modify the dispersion relation and change the property of ground state of the condensate. For the non-equilibrium state, the spin-orbit coupling plays an important role in the spin mixing dynamics. Moreover, the oscillation period of spin mixing dynamics is determined by the coupled effects of momentum, magnetization, spin-dependent atomic interaction and spin-orbit coupling. When spin-orbit coupling is less than a critical value, it can prolong the oscillation period of spin mixing dynamics. Conversely, when the spin-orbit coupling is larger than the critical value, it can shorten the oscillation period of spin mixing dynamics. Particularly, when spin-orbit coupling is equal to the critical value, the period tends to infinity. Our study provides a complete spin mixing dynamics of spin-orbit coupled spin-1 BEC, which can be used to explore the spin mixing dynamics experimentally.

The identification of communities has attracted considerable attentions in the last few years. We propose a novel heuristic algorithm for overlapping community detection based on community cores in complex networks. We introduce a novel clique percolation algorithm and maximize cliques in the finding overlapping communities (node covers) in graphs. We show how vertices can be used to quantify types of local structure presented in a community and identify group nodes that have similar roles in relation to their neighbors. We compare the approach with other three common algorithms in the analysis of the Zachary’s karate club network and the dolphins network. Experimental results in real-world and synthetic datasets (Lancichinetti–Fortunato–Radicchi (LFR) benchmark networks [A. Lancichinetti and S. Fortunato, Phys. Rev. E 80 (2009) 016118]) demonstrate the model has scalability and is well behaved.

A numerical study is performed to investigate the hydrodynamics of a square near the wall. The fluid dynamics around this bluff body is considered at the Reynolds number Re ≈ 100. The numerical results show that the time-varying force on the square would keep static when the gap between the square and wall is smaller, while it varyingly changes at higher gap. Moreover, the time-mean drag on the square firstly increases and then decreases with keeping increase of the gap between the square and wall, while the time-mean lift on the square gradually decreases. This finding may be helpful for designing the offshore structure in a varied oceanic topography.

The resonant nonlinear Schrödinger equation is studied in this work with the aid of two methods, namely the exponential rational function method and the modified exponential function method. This equation is used to describe the propagation of optical pulses in nonlinear optical fibers. Being concise and straightforward, these methods are used to build new exact analytical solutions of the model. The solutions obtained are not yet reported in the literature. The methods proposed can be extended to other types of nonlinear evolution equations in mathematical physics.

In order to study the initial nucleation and growth process of the films, a two-dimensional (2D) DLA model was established, and fractal dimension was calculated by sandbox method. Compared with the experimental results, the model can well characterize the morphology of nucleation and growth in the initial stage of film growth. In addition to the number of particles and deposition probability involved in other studies, the size of substrate and the location of central particles are also considered in this work. The growth morphology, fractal dimension and the number of simulated steps are presented in this paper.

In this work, we study the modified Volterra lattice. Applying the gauge transformation of the associated $2\times 2$ matrix spectral problems, we establish the N-fold Darboux transformation (DT), and then construct a few explicit solutions in terms of determinants upon using the obtained DT. Moreover, all the results are illustrated by the graphs of the solitonic evolution profiles of the aforementioned solutions. Finally, infinitely many conservation laws for the modified Volterra lattice are proposed. The obtained results of this research might be applied to the research on nonlinear phenomena in physics or engineering areas.

In this paper, we construct the Hamiltonian description of the closed vortex filament dynamics in terms of non-standard variables, phase space and constraints. The suggested approach makes obvious interpretation of the considered system as a structured particle that possesses certain external and internal degrees of the freedom. The constructed theory is invariant under the transformation of Galilei group. The appearance of this group allows for a new viewpoint on the energy of a closed vortex filament with zero thickness. The explicit formula for the effective mass of the structured particle “closed vortex filament” is suggested.

The dielectric properties of sodium silicate (Na₂SiO₃) (SS) have been investigated in a wide range of frequencies and temperatures. A strong dielectric dispersion is found to exist in low-frequency region. The frequency-dependent dielectric properties of SS follow the universal dynamic response proposed by Jonscher. The measured dielectric data strongly depends on dielectric dispersion and controls the basic relaxation property. However, the parameters that control the frequency-dependent dielectric properties such as coupling of ions or polarizability are found to have peak values at the frozen out condition or critical point.

Non-equilibrium Green’s function method is applied to study the spin thermoelectric effects in a four-quantum-dot ring with two of the quantum dots magnetized. The influence of magnetic configuration on the spin thermoelectric transport through the system is investigated. In some magnetic configurations, a significant spin Seebeck coefficient $S_s$ can be generated with the variation of the quantum dot (QD) energy level. Appropriately tuning the QD energy level can let the present device work as a pure spin-up (spin-down) or a pure-spin-current thermal generator. The combined effect of the magnetization and magnetic flux (or Rashba spin-orbit coupling) is also investigated. Finally, the charge figure of merit $Z_{c}T$ and spin figure of merit $Z_{s}T$ are evaluated, it is found that the magnitude of the spin figure of merit can be comparable to that of the charge counterpart.

In this paper, the group classification is presented for Fisher equation with time-dependent coefficients. The analysis provided many new solutions that take the form of doubly periodic-like solutions and soliton-like solutions.

The configurations, electronic and spin of the FeN–HNCO clusters are calculated at PW91 basis set. The results indicate that a chain structure of H–N–N–Fe–C–O possesses the highest structural and kinetic stability. The FeN–HNCO cluster which possesses an Fe–N–C–N quadrangular ring displays the highest adsorption capacity between FeN and HNCO. The isomer (16) which possesses the chain configuration has higher kinetic activity. The $2p3d$ orbitals of C and N atoms of the FeN–HNCO clusters gain electrons and the $2s$ orbital of C and N atoms of the FeN–HNCO clusters loss electrons. The chain structure of the isomer (17) has the largest total spin (2.955 ${\mu }_B$/atom) than the others.

The quality and assessment of a catalyst can be documented in detail by the application of pore size. This research aims to calculate fractal dimension from the relationship among pore size, maximum pore size and wetting phase saturation and to confirm it by the fractal dimension derived from the relationship among the ratio between surface area per unit pore volume, entry surface area per unit pore volume and wetting phase saturation. In this research, pore size was measured on Au/TiO₂ using Brunauer–Emmett–Teller (BET) surface area. Two equations for calculating the fractal dimensions have been employed. The first one describes the functional relationship between wetting phase saturation, pore size, maximum pore size and fractal dimension. The second equation implies to the wetting phase saturation as a function of surface area per unit pore volume, entry surface area per unit pore volume and the fractal dimension. Two procedures for obtaining the fractal dimension have been utilized. The first procedure was done by plotting the logarithm of the ratio between pore size and maximum pore size versus logarithm wetting phase saturation. The positive slope of the first procedure = 3 − Df (fractal dimension). The second procedure for obtaining the fractal dimension was determined by plotting the logarithm of the ratio between surface area per unit pore volume, entry surface area per unit pore volume versus the logarithm of wetting phase saturation. The negative slope of the second procedure = Df − 3. It was found that the plasma + thermally treated Au/TiO₂ has the highest fractal dimension value owing to possibility of having holes and channels. The results also show similarity between pore size fractal dimension and surface area per unit pore volume fractal dimension. In our case, as conclusions, the higher the fractal dimension, the better the catalytic activity.