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1.
A Dynamic Model for a Single Helicopter in the Low Airspace with Telegraph Poles and Electrical Wire
TANG Tie-Qiao 《理论物理通讯》2011,56(6):1149-1154
In this paper, we propose a dynamic model for a single helicopter in the low airspace with telegraph poles and electrical wire. The numerical results show that the proposed model can qualitatively describe the helicopter's velocity, safe distances, and safe sphere when it runs across the obstacle consisting of telegraph poles and electrical wire. 相似文献
2.
An explicit cross-property connection for a rough interface between the electrical contact resistance and dynamic contact stiffness has been established in the low-frequency limit. The present analysis is based on the first-order asymptotic model of multiple dynamic contact between small flat-ended indenters on an elastic half-space, which is a dynamic analogue of the quasi-static Greenwood model. The obtained results can be used in developing a vibration method for measuring the interface contact stiffness in tribological systems, and in estimating the surface-roughness effect in oscillation indentation tests. 相似文献
3.
WANG Xiao-Ming ZHOU Bang-Rong 《理论物理通讯》2007,47(6):1081-1087
A general research on chiral symmetry restoring phase transitions at zero temperature and finite chemical potentials under electrical neutrality condition has been conducted in a Nambu-Jona-Lasinio model to describe twoflavor normal quark matter. Depending on whether mo/A, the ratio of dynamical quark mass in vacuum and the 3D momentum cutoff in the loop integrals, is less or greater than 0.413, the phase transition will be of the second or first order. A complete phase diagram of u quark chemical potential versus mo is given. With the electrical neutrality constraint, the region where the second order phase transition happens will be wider than the one without electrical neutrality limitation. The results also show that, for the value of m0/∧ from QCD phenomenology, the phase transition must be of the first order. 相似文献
4.
The dynamic phase transition has been studied, within a mean-field approach, in the kinetic spin-3/2 Ising model Hamiltonian
with arbitrary bilinear and biquadratic pair interactions in the presence of a time dependent oscillating magnetic field by
using the Glauber-type stochastic dynamics. The nature (first- or second-order) of the transition is characterized by investigating
the behavior of the thermal variation of the dynamic order parameters and as well as by using the Liapunov exponents. The
dynamic phase transitions (DPTs) are obtained and the phase diagrams are constructed in the temperature and magnetic field
amplitude plane and found nine fundamental types of phase diagrams. Phase diagrams exhibit one, two or three dynamic tricritical
points, and besides a disordered (D) and the ferromagnetic-3/2 (F3/2) phases, six coexistence phase regions, namely F
3/2+ F
1/2, F
3/2+ D, F
3/2+ F
1/2+ FQ, F
3/2+ FQ, F
3/2+ FQ + D and FQ + D, exist in which depending on the biquadratic interaction.
PACS number(s): 05.50.+q, 05.70.Fh, 64.60.Ht, 75.10.Hk 相似文献
5.
Toufik Boubehziz Carlos Quesada-Granja Claire Dupont Pierre Villon Florian De Vuyst Anne-Virginie Salsac 《Entropy (Basel, Switzerland)》2021,23(9)
An innovative data-driven model-order reduction technique is proposed to model dilute micrometric or nanometric suspensions of microcapsules, i.e., microdrops protected in a thin hyperelastic membrane, which are used in Healthcare as innovative drug vehicles. We consider a microcapsule flowing in a similar-size microfluidic channel and vary systematically the governing parameter, namely the capillary number, ratio of the viscous to elastic forces, and the confinement ratio, ratio of the capsule to tube size. The resulting space-time-parameter problem is solved using two global POD reduced bases, determined in the offline stage for the space and parameter variables, respectively. A suitable low-order spatial reduced basis is then computed in the online stage for any new parameter instance. The time evolution of the capsule dynamics is achieved by identifying the nonlinear low-order manifold of the reduced variables; for that, a point cloud of reduced data is computed and a diffuse approximation method is used. Numerical comparisons between the full-order fluid-structure interaction model and the reduced-order one confirm both accuracy and stability of the reduction technique over the whole admissible parameter domain. We believe that such an approach can be applied to a broad range of coupled problems especially involving quasistatic models of structural mechanics. 相似文献
6.
We calculate the dynamic phase transition (DPT) temperatures and present the dynamic phase diagrams in the kinetic mixed spin-1/2 and spin-5/2 Ising model under the presence of a time-dependent oscillating external magnetic field. We employ the Glauber transition rates to construct the set of mean-field dynamic equations. The time variation of the average magnetizations and the thermal behavior of the dynamic magnetizations are investigated, extensively. The nature (continuous or discontinuous) of the transitions is characterized by studying the thermal behaviors of the dynamic magnetizations. The DPT points are obtained and the phase diagrams are presented in two different planes. Phase diagrams contain four fundamental phases and three coexistence or mixed phases, which strongly depend on interaction parameters. The phase diagrams are discussed and a comparison is made with the results of the other mixed spin Ising systems. 相似文献
7.
TANG Tie-Qiao HUANG Hai-Jun S.C. Wong GAO Zi-You ZHANG Ying 《理论物理通讯》2009,51(1):71-78
In this paper, we present a new macro model for traffic flow on a highway with ramps based on the existing models. We use the new model to study the effects of on-off-ramp on the main road traffic during the morning rush period and the evening rush period. Numerical tests show that, during the two rush periods, these effects are often different and related to the status of the main road traffic. If the main road traffic flow is uniform, then ramps always produce stop-and-go traffic when the main road density is between two critical values, and ramps have little effect on the main road traffic when the main road density is less than the smaller critical value or greater than the larger critical value. If a small perturbation appears on the main road, ramp may lead to stop-and-go traffic, or relieve or even eliminate the stop-and-go traffic, under different circumstances. These results are consistent with real traffic, which shows that the new model is reasonable. 相似文献
8.
A new approach to design control systems for an industrial furnace with flue gas recirculation (FGR) is presented. To facilitate the control system design, a linear dynamic model is needed for the furnace. Full-scale computational fluid dynamics (CFD) simulations are used to generate the required small signal input and output data sets. Subsequently, a least squares based system identification technique is used to obtained the linear dynamic models. After model validation, feedback controller is designed based on these linear dynamic models. Finally, the performance of the designed closed-loop control system is also evaluated using both linear dynamic model and full-scale nonlinear CFD model. The comparison shows that the control system designed using the proposed approach can minimize the deviation of nitric oxides (NO) emission from the design point by minimize the dynamic NO formation, hence to prevent any excessive NO formation in the combustion process when the system subjects to disturbances. 相似文献
9.
We explore the NJL model with Polyakov loops for a system of three colors and two flavors within the mean-field approximation, where both chiral symmetry and confinement are taken into account. We focus on the phase structure of the model and study the chiral and Polyakov loop susceptibilities. 相似文献
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11.
Langlands Robert P. Lewis Marc-André Saint-Aubin Yvan 《Journal of statistical physics》2000,98(1-2):131-244
The partition function with boundary conditions for various two-dimensional Ising models is examined and previously unobserved properties of nonformal invariance and universality are established numerically. 相似文献
12.
Sayyed Mostafa Habibi‐Khorassani Malek Taher Maghsoodlou Ali Ebrahimi Marzyeh Mohammadi Mehdi Shahraki Elham Aghdaei 《Journal of Physical Organic Chemistry》2012,25(12):1328-1335
In the present work, the dynamic 1H NMR effects were investigated at variable temperatures within a particular phosphorus ylide involving a 2‐benzoxazolinone around the carbon–carbon single bond and also partial carbon–carbon double bond in two Z‐ and E‐rotational isomers. Activation and kinetic parameters including ΔH≠, ΔG≠, ΔS≠ and Ea were determined in accord with the dynamic 1H NMR data for three rotational processes. In addition, theoretical studies based upon rotation around the same bonds were investigated using ab initio and DFT methods at the HF/6‐31G(d,p) and B3LYP/6‐31G(d,p) levels of theory. Theoretical activation and kinetic parameters including ΔH≠, ΔG≠, ΔS≠ and Ea were calculated at 298 K and experimental temperatures for five rotational processes. These results (experimental and theoretical), taken together, indicate that the rotational energy barrier around the C = C double bond was considerably high and the observation of the two rotational isomers was impossible (seen as a single isomer) at the high temperatures, in this case rotation around the C = C bond was too fast on the NMR time scale. When the temperature was relatively low, the rate of rotation was sufficiently slow; therefore, observation of the two Z‐ and E‐isomers was possible. In addition, calculations at the HF/6‐31G(d,p) level of theory showed very favorable results in agreement with the experimental data on rotation around the C = C bond. While, B3LYP level using the 6‐31G(d,p) basis set was provided the reasonable data for the restricted rotations around the C–C and C–N single bond. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
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We derive new expressions to estimate the burning velocity of a laminar gas flame in a simplified combustion model based on a one-step single reaction with transport coefficients (mass and heat) depending on temperature, and species with different specific heats. These new expressions generalize the bounds and approximations previously derived by Williams, von Karman, Zeldovich and Frank-Kamenetskii, Benguria and Depassier, and the matching asymptotic expansion method in a two zone model. The comparison of the flame speed predicted by these new analytical expressions with that numerically simulated by the full combustion model for a large variety of cases allows us to determine their range of validity. The upper bound based on the Benguria and Depassier method provides very good approximations for the actual propagation speed of combustion flames, being substantially better than the asymptotic method used in the recent papers. 相似文献
17.
Post-polio syndrome refers to the physical and psychological sequelae caused by poliovirus infection. For this reason, according to which the emotional and sensorimotor sphere is affected, we consider a biobehavioural approach based on education and therapeutic exercise to be necessary. The aim of this case report is to evaluate the effect of a biobehavioural approach in a patient with post-polio syndrome and low back pain. We describe a 57-year-old man with post-polio syndrome and low back pain following a fall at the end of February 2020. The pain, disability and lack of functionality caused by both processes led him to contact a physiotherapy service. A therapeutic planning was carried out for 3 months, where a biobehavioural approach based on therapeutic exercise and education, with an assessment and three face-to-face sessions which were complemented by online follow-up and finalised due to the Sars-Cov-2 pandemic in a telerehabilitation approach. It was organised in two phases; the initial phase lasted 2 weeks with the aim of reducing the symptoms of the lumbar region, and the advanced phase in which the aim was to improve his physical condition. During the three-month intervention, four assessments were conducted (Pre, at 4 weeks, at 8 weeks and at 12 weeks). At follow-up, improvements in functional and psychological variables were obtained. This case suggests that a biobehavioural approach through telerehabilitation was a useful option in this reported case and could be an option of treatment to improve psychological, physical and functional variables in this patient. 相似文献
18.
Sayed Abdel-Khalek Kamal Berrada Eied M. Khalil Abdel-Shafy F. Obada Esraa Reda Hichem Eleuch 《Entropy (Basel, Switzerland)》2021,23(5)
In this work, we introduce the standard Tavis-Cummings model to describe two-qubit system interacting with a single-mode field associated to power-law (PL) potentials. We explore the effect of the time-dependent interaction and the Kerr-like medium. We solve the Schrödinger equation to obtain the density operator that allows us to investigate the dynamical behaviour of some quantumness measures, such as von Neumann entropy, negativity and Mandel’s parameter. We provide how these entanglement measures depend on the system parameters, which paves the way towards better control of entanglement generation in two-qubit systems. We find that the enhancement and preservation of the atoms-field entanglement and atom-atom entanglement can be achieved by a proper choice of the initial parameters of the field in the absence and presence of the time-dependent interaction and Kerr medium. We examine the photons distribution of the field and determine the situations for which the field exhibits super-poissonian, poissonian or sub-poissonian distribution. 相似文献
19.
G.H. Peng 《Physica A》2012
In this paper, a new lattice model of traffic flow is proposed to investigate wide moving jams in traffic flow with the consideration of the driver anticipation information about two preceding sites. The linear stability condition is obtained by using linear stability analysis. The mKdV equation is derived through nonlinear analysis, which can be conceivably taken as an approximation to a wide moving jam. Numerical simulation also confirms that the congested traffic patterns about wide moving jam propagation in accordance with empirical results can be suppressed efficiently by taking the driver anticipation effect of two preceding sites into account in a new lattice model. 相似文献
20.
The transverse momentum spectra of different types of particles, , , p and , produced at mid-(pseudo)rapidity in different centrality lead–lead (Pb–Pb) collisions at 2.76 TeV; proton–lead (p–Pb) collisions at 5.02 TeV; xenon–xenon (Xe–Xe) collisions at 5.44 TeV; and proton–proton (p–p) collisions at 0.9, 2.76, 5.02, 7 and 13 TeV, were analyzed by the blast-wave model with fluctuations. With the experimental data measured by the ALICE and CMS Collaborations at the Large Hadron Collider (LHC), the kinetic freeze-out temperature, transverse flow velocity and proper time were extracted from fitting the transverse momentum spectra. In nucleus–nucleus (A–A) and proton–nucleus (p–A) collisions, the three parameters decrease with the decrease of event centrality from central to peripheral, indicating higher degrees of excitation, quicker expansion velocities and longer evolution times for central collisions. In p–p collisions, the kinetic freeze-out temperature is nearly invariant with the increase of energy, though the transverse flow velocity and proper time increase slightly, in the considered energy range. 相似文献