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The migration of deformable bubbles with different sizes near a vertical wall in pure water was experimentally studied by the dual-camera orthogonal shadow method. The key factors affecting the migration are discussed. It was found that the effect of size and initial distance on bubble migration is indirect. For bubbles of the same diameter (deq=3.10 mm), the same mode occurs when the initial distance (0.5≤L* ≤3.5) is changed. When the initial distance (L* =0.5) is constant, the same mode appears for bubbles of different sizes (2.27 mm≤deq≤3.40 mm). Furthermore, different modes are found in the same initial distance (L* =0.5) and size (deq=3.10 mm). In fact, the migration mode is determined by the initial distance, Reynolds number and Weber number. The size and initial distance can influence the frequency of different modes. Considering a variety of factors, four basic migration modes are summarized. New correlations are proposed to predict bubble behavior in different modes near the wall. The kinematic and dynamic parameters of different modes are discussed. It is expected that the results can be helpful to predict the gas-liquid flow near a wall and to improve related heat and mass transfer process. [ABSTRACT FROM AUTHOR]

Adding a small amount of surfactant to gas-liquid two-phase flow can markedly change bubble behavior, which has crucial application value in nuclear energy, petrochemical, chemical, and environmental engineering. In this paper, the dynamic behavior of a single ellipsoidal bubble (Re∼800) contaminated by surfactant rising near a vertical wall in stagnant liquid is studied using the shadow method. The effects of different concentrations of sodium dodecyl sulfate solution (100 ppm, 400 ppm, 800 ppm) and initial dimensionless distances on bubble dynamics were compared. The dynamic parameters, shape oscillation, force, and energy of the bubble were analyzed. The results show that the critical initial dimensionless distance at which the collision occurs is decreased due to a dimensionless distance change from 3.3 to 0.23, accelerating the transition from zigzag to spiral movement. Transverse movement of the contaminated bubble is restrained. Because of the Marangoni effect caused by the surfactant, the boundary condition changes from zero shear to non-zero shear, resulting in a decrease in velocity and an increase in the drag coefficient. As the surfactant concentration increases, the lift coefficient does not significantly change with concentration variations. The influences of the wall effect on velocity and drag gradually weaken. Comparing free-rising and collision conditions, the aspect ratio of the contaminated bubble is distinct from the regularity of a clean bubble. The surfactant also changes the wall-normal velocity frequency and symmetrical shape frequency and inhibits energy conversion during collision. [ABSTRACT FROM AUTHOR]

In real-world scenarios, the uncertainty of measurements cannot be handled efficiently by traditional model predictive control (MPC). A stochastic MPC (SMPC) method for handling the uncertainty of states in autonomous driving lane-keeping scenarios is presented in this paper. A probabilistic system is constructed by considering the variance of states. The probabilistic problem is then transformed into a solvable deterministic optimization problem in two steps. First, the cost function is separated into mean and variance components. The mean component is calculated online, whereas the variance component can be calculated offline. Second, Cantelli's inequality is adopted for the deterministic reformulation of constraints. Consequently, the original probabilistic problem is transformed into a quadratic programming problem. To validate the feasibility and effectiveness of the proposed control method, we compared the SMPC controller with a traditional MPC controller in a lane-keeping scenario. The results demonstrate that the SMPC controller is more effective overall and produces smaller steady-state distance errors. [ABSTRACT FROM AUTHOR]

In this paper, we study several physically feasible quantum secret sharing (QSS) schemes using continuous variable graph state (CVGS). Their implementation protocols are given, and the estimation error formulae are derived. Then, we present a variety of results on the theory of QSS with CVGS. Any $$(k,n)$$ threshold protocol of the three specific schemes satisfying $$\frac{n}{2}