By employing the perturbative QCD (PQCD) factorization approach, we made a systematic investigation for the CP-averaged branching ratios and the CP-violating asymmetries of the thirteen B¯s0 → P P decays (here P...
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In this paper, we will make systematic calculations for the branching ratios and the CP-violating asymmetries of the twenty one B¯s0 → P V decays by employing the perturbative QCD (PQCD) factorization approach. ...
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The reduction of surface energy is a well-known driving force for the fragmentation of nanowires. Fragmentation can limit the service life of those small low-dimensional building blocks or can be controlled to induce ...
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The reduction of surface energy is a well-known driving force for the fragmentation of nanowires. Fragmentation can limit the service life of those small low-dimensional building blocks or can be controlled to induce beneficial shape changes. For isotropic surface energy, fragmentation is analogous to the classic Rayleigh-Plateau instability of liquid jets. However, commonly synthesized crystalline nanowires have strongly anisotropic surface energies and exhibit facets coinciding with cusps in the Wulff plot. Depending on growth orientation, different fragmentation behaviors have been seen in nanowires. Using phase-field simulations, we show that fragmentation of faceted nanowires with cubic crystal symmetry may occur by a finite-amplitude nonlinear instability, as opposed to a Rayleigh-Plateau-like linear instability, depending on nanowire growth orientation. We carry out a weakly nonlinear analysis based on sharp interface theory to characterize the faceted nanowire shape corresponding to a surface-energy saddle point. The analysis predicts that the minimum amplitude of a periodic shape perturbation to trigger fragmentation increases with cusp strength but decreases inversely proportionally to the perturbation wavelength for long wavelengths, in good quantitative agreement with phase-field predictions. The results provide the theoretical foundation to predict nanowire stability as a function of length and surface energy in diverse applications.
The convective heat transfer of the cold cabinet was investigated by using two-fluid model after the effectiveness of new model was confirmed. This study includes the influence of wind speeds, wind directions and spee...
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The convective heat transfer of the cold cabinet was investigated by using two-fluid model after the effectiveness of new model was confirmed. This study includes the influence of wind speeds, wind directions and speeds of air curtain. The results show that the convective heat transfer is improved along with increasing of the wind speed. In a relatively short time, there is a linear relationship between convective heat transfer and time. The wind direction has small effect on heat transfer when it is less than about 15° while has appreciable impact and made an increase of energy consumption by approximately 30% when it reaches 30°. The air curtain, a major constituent of the refrigeration system of cold cabinet, provides a barrier of moving air across a door opening and reduces heat transfer by preventing the penetration of hot air. The simulation shows that there is the minimum speed and the best speed range of air curtain. The air curtain can not be formed when the speed is less than 1.5 m·s-1, while has a large spillover of cold air when it is greater than 3.0 m·s-1. From the above, the best speed of air curtain ranges from 2.6 m·s-1 to 3.0 m·s-1.
A new phase-shifting error compensating algorithm for phase-measuring profilometry is proposed. In this error detecting algorithm, it is supposed that sinusoidal fringe is projected to the plate, thus the phase differ...
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A new phase-shifting error compensating algorithm for phase-measuring profilometry is proposed. In this error detecting algorithm, it is supposed that sinusoidal fringe is projected to the plate, thus the phase differences between adjacent pixels are equal. Three adjacent phase points are taken as the research object. Combining the principle of phase compensation measurement, each phase of the point is presented as an equation containing the phase-shifting error. According to the characteristics that the phase differences between adjacent pixels are equal, an equation to calculate the phase-shifting error is constructed. Then the phase shifting error is taken into account in the original algorithm for error compensation. Simulation results show the inhibitory effect of the error compensation by using the novel algorithm. The proposed algorithm is also used for three-dimensional reconstruction. The final result shows that the new compensation algorithm is better than the original one obviously. This error compensating algorithm can effectively improve the accuracy of three-dimensional measurement.
Particle swarm optimization is a focus on queue control, path optimization, destination search, and so on in multiple robot systems, of which the main idea is that the optimization solution of swarm behaviors are to b...
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Particle swarm optimization is a focus on queue control, path optimization, destination search, and so on in multiple robot systems, of which the main idea is that the optimization solution of swarm behaviors are to be obtained through iteration update of velocities and coordinate positions of particles. Based on analysis of particle swarm principle and of mechanism of its main parameters, comparative researches on particle swarm with genetic algorithm, ant colony algorithm, and neural network are given, respectively. Then a survey on research progresses of particle swarm optimization and relative modified new optimization algorithms applied in robot/multi-robot systems is given. Finally, the outlook of future work on particle swarm optimization applied in multi-robot systems under community perception networks is proposed.
Compared with traditional design methods, generative design significantly attracts engineers in various disciplines. In thiswork, howto achieve the real-time generative design of optimized structures with various dive...
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During the coal seam drilling process, the drill string is subject to compressive deformation, compounded by unpredictable variations in formation hardness and borehole wall friction, leading to challenges in maintain...
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ISBN:
(数字)9798350368604
ISBN:
(纸本)9798350368611
During the coal seam drilling process, the drill string is subject to compressive deformation, compounded by unpredictable variations in formation hardness and borehole wall friction, leading to challenges in maintaining a stable feeding speed. This paper presents a novel approach by introducing uncertain parameters to describe the effects of formation hardness and borehole wall friction. Drill string axial movement model is modeled as a polyhedral system based on a lumped parameter representation. To meet industrial performance requirements, we design a robust $H_{\infty}$ controller to achieve consistent feeding speed control. Our simulation results demonstrate the controller's effectiveness in ensuring system stability despite fluctuations in formation hardness and drill string friction.
In this paper, an adaptive iterative learning control (ILC) scheme is proposed for trajectory tracking of uncertain delay systems based on model matching technique. The reference model is a delay system operating over...
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In this paper, an adaptive iterative learning control (ILC) scheme is proposed for trajectory tracking of uncertain delay systems based on model matching technique. The reference model is a delay system operating over in a finite time interval. An iterative model matching controller is designed and an iteration domain adaptive law is chosen to estimate the unknown parameters. It shows that the model matching technique can be applied in a straightforward method to ILC problem. A simulation example is included to illustrate the designed scheme.
This paper is devoted to the problem of state estimate of discrete-time stochastic systems with Markov jump parameters. A robust algorithm-diagonal interacting multiple model algorithm based on H_∞ filtering (DIMMH) ...
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ISBN:
(纸本)9781479901777
This paper is devoted to the problem of state estimate of discrete-time stochastic systems with Markov jump parameters. A robust algorithm-diagonal interacting multiple model algorithm based on H_∞ filtering (DIMMH) is presented for maneuvering target tracking when measurement noise is of unknown statistics. Extensive Monte Carlo simulations show the effectiveness and superiority of the proposed algorithm.
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