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<jats:p>When large tumors are treated, ablation of the entire volume of tumors requires multiple treatment spots formed by high intensity-focused ultrasound (HIFU) scanning therapy. The heating effect of HIFU on biological tissue is mainly reflected in temperature elevation and tissue lesions. Tissue property parameters vary with temperature and, in turn, the distribution of temperature as well as the heating effects change accordingly. In this study, an HIFU scanning therapy model considering dynamic tissue properties is provided. The acoustic fields and temperature fields are solved combining the Helmholtz wave equation with Pennes bio-heat transfer equation based on the finite element method (FEM) to investigate the effects of various tissue properties (<jats:italic>i.e.</jats:italic>, the attenuation coefficient, acoustic velocity, thermal conductivity, specific heat capacity, density, and blood perfusion rate) on heating performance. Comparisons of the temperature distribution and thermal lesions under static and dynamic properties are made based on the data of tissue property parameters varying with temperature. The results show that the dynamic changes of thermal conductivity, specific heat capacity, and acoustic velocity may account for the decrease of temperature elevation in HIFU treatment, while the dynamic changes of attenuation coefficient, density, and blood perfusion rate aggravate the increase of temperature on treatment spots. Compared with other properties, the dynamic change of attenuation coefficient has a greater impact on tissue temperature elevation. During HIFU scanning therapy, the temperature elevation and tissue lesions of the first treatment spot are smaller than those of the subsequent treatment spots, but the temperature on the last treatment spot drops faster during the cooling period. The ellipsoidal tissue lesion is not symmetrical; specifically, the part facing toward the previous treatment spot tends to be larger. Under the condition of the same doses, the temperature elevation and the size of tissue lesions under dynamic properties present significant growth in comparison to static properties. Besides, the tissue lesion begins to form earlier with a more unsymmetrical shape and is connected to the tissue lesion around the previous treatment spot. As a result, lesions around all the treatment spots are connected with each other to form a closed lesion region. The findings in this study reveal the influence of dynamic tissue properties on temperature elevation and lesions during HIFU scanning therapy, providing useful support for the optimization of treatment programs to guarantee higher efficacy and safety.</jats:p>

<jats:p>We propose an extended cellular automaton model based on the floor field. The floor field can be changed accordingly in the presence of pedestrians. Furthermore, the effects of pedestrians with different speeds are distinguished, <jats:italic>i.e.</jats:italic>, still pedestrians result in more increment of the floor field than moving ones. The improved floor field reflects impact of pedestrians as movable obstacles on evacuation process. The presented model was calibrated by comparing with previous studies. It is shown that this model provides a better description of crowd evacuation both qualitatively and quantitatively. Then we investigated crowd evacuation from a middle-size theater. Four possible designs of aisles in the theater are studied and one of them is the actual design in reality. Numerical simulation shows that the actual design of the theater is reasonable. Then we optimize the position of the side exit in order to reduce the evacuation time. It is shown that the utilization of the two exits at bottom is less than that of the side exits. When the position of the side exit is shifted upwards by about 1.6 m, it is found that the evacuation time reaches its minimum.</jats:p>

<jats:p>The Z–S–C multiphase lattice Boltzmann model [Zheng, Shu, and Chew (ZSC), <jats:italic>J. Comput. Phys.</jats:italic> <jats:bold>218</jats:bold>, 353 (2006)] is favored due to its good stability, high efficiency, and large density ratio. However, in terms of mass conservation, this model is not satisfactory during the simulation computations. In this paper, a mass correction is introduced into the ZSC model to make up the mass leakage, while a high-order difference is used to calculate the gradient of the order parameter to improve the accuracy. To verify the improved model, several three-dimensional multiphase flow simulations are carried out, including a bubble in a stationary flow, the merging of two bubbles, and the bubble rising under buoyancy. The numerical simulations show that the results from the present model are in good agreement with those from previous experiments and simulations. The present model not only retains the good properties of the original ZSC model, but also achieves the mass conservation and higher accuracy.</jats:p>

<jats:p>Aiming at the interaction and coalescence of bubbles in gas–liquid two-phase flow, a multi-field coupling model was established to simulate deformation and dynamics of multi-bubble in gas–liquid two-phase flow by coupling magnetic field, phase field, continuity equation, and momentum equation. Using the phase field method to capture the interface of two phases, the geometric deformation and dynamics of a pair of coaxial vertical rising bubbles under the applied uniform magnetic field in the vertical direction were investigated. The correctness of results is verified by mass conservation method and the comparison of the existing results. The results show that the applied uniform magnetic field can effectively shorten the distance between the leading bubble and the trailing bubble, the time of bubbles coalescence, and increase the velocity of bubbles coalescence. Within a certain range, as the intensity of the applied uniform magnetic field increases, the velocity of bubbles coalescence is proportional to the intensity of the magnetic field, and the time of bubbles coalescence is inversely proportional to the intensity of the magnetic field.</jats:p>

<jats:p>The electrohydrodynamic behaviors and evolution processes of silicone oil droplet in castor oil under uniform direct current (DC) electric field are visually observed based on a high-speed microscopic platform. Subsequently, the effects of different working conditions, such as electric field strength, droplet size, <jats:italic>etc</jats:italic>., on droplet behaviors are roundly discussed. It can be found that there are four droplet behavior modes, including Taylor deformation, typical oblique rotation, periodic oscillation, and fracture, which change with the increase of electric field strength. It is also demonstrated that the degree of flat ellipse deformation gets larger under a stronger electric field. Moreover, both of the stronger electric field and smaller droplet size lead to an increase in the rotation angle of the droplet.</jats:p>

<jats:p>Taking the Rayleigh–Taylor instability with double interfaces as the research object, the interface coupling effects in the weakly nonlinear regime are studied numerically. The variation of Atwood numbers on the two interfaces and the variation of the thickness between them are taken into consideration. It is shown that, when the Atwood number on the lower interface is small, the amplitude of perturbation growth on the lower interface is positively related with the Atwood number on the upper interface. However, it is negatively related when the Atwood number on the lower interface is large. The above phenomenon is quantitatively studied using an analytical formula and the underlying physical mechanism is presented.</jats:p>

<jats:p>The effect of high overdrive voltage on the positive bias temperature instability (PBTI) trapping behavior is investigated for GaN metal–insulator–semiconductor high electron mobility transistor (MIS-HEMT) with LPCVD-SiN<jats:sub> <jats:italic>x</jats:italic> </jats:sub> gate dielectric. A higher overdrive voltage is more effective to accelerate the electrons trapping process, resulting in a unique trapping behavior, <jats:italic>i.e</jats:italic>., a larger threshold voltage shift with a weaker time dependence and a weaker temperature dependence. Combining the degradation of electrical parameters with the frequency–conductance measurements, the unique trapping behavior is ascribed to the defect energy profile inside the gate dielectric changing with stress time, new interface/border traps with a broad distribution above the channel Fermi level are introduced by high overdrive voltage.</jats:p>

<jats:p>The microwave plasma oxidation under the relatively high pressure (6 kPa) region is introduced into the fabrication process of SiO<jats:sub>2</jats:sub>/4H-SiC stack. By controlling the oxidation pressure, species, and temperature, the record low density of interface traps (∼ 4 × 10<jats:sup>10</jats:sup> cm<jats:sup>−2</jats:sup>⋅eV<jats:sup>−1</jats:sup>@<jats:italic>E<jats:sub>c</jats:sub> </jats:italic> − 0.2 eV) is demonstrated on SiO<jats:sub>2</jats:sub>/SiC stack formed by microwave plasma oxidation. And high quality SiO<jats:sub>2</jats:sub> with very flat interface (0.27-nm root-mean-square roughness) is obtained. High performance SiC metal–oxide–semiconductor field-effect transistors (MOSFETs) with peak field effect mobility of 44 cm<jats:sup>−2</jats:sup> ⋅eV<jats:sup>−1</jats:sup> is realized without additional treatment. These results show the potential of a high-pressure plasma oxidation step for improving the channel mobility in SiC MOSFETs.</jats:p>

<jats:p>Aluminum-doped ZnO (AZO) thin films with thin film metallic glass of Zr<jats:sub>50</jats:sub>Cu<jats:sub>50</jats:sub> as buffer are prepared on glass substrates by the pulsed laser deposition. The influence of buffer thickness and substrate temperature on structural, optical, and electrical properties of AZO thin film are investigated. Increasing the thickness of buffer layer and substrate temperature can both promote the transformation of AZO from amorphous to crystalline structure, while they show (100) and (002) unique preferential orientations, respectively. After inserting Zr<jats:sub>50</jats:sub>Cu<jats:sub>50</jats:sub> layer between the glass substrate and AZO film, the sheet resistance and visible transmittance decrease, but the infrared transmittance increases. With substrate temperature increasing from 25 °C to 520 °C, the sheet resistance of AZO(100 nm)/Zr<jats:sub>50</jats:sub>Cu<jats:sub>50</jats:sub>(4 nm) film first increases and then decreases, and the infrared transmittance is improved. The AZO(100 nm)/Zr<jats:sub>50</jats:sub>Cu<jats:sub>50</jats:sub>(4 nm) film deposited at a substrate temperature of 360 °C exhibits a low sheet resistance of 26.7 Ω/□, high transmittance of 82.1% in the visible light region, 81.6% in near-infrared region, and low surface roughness of 0.85 nm, which are useful properties for their potential applications in tandem solar cell and infrared technology.</jats:p>

<jats:p>According to the one-dimensional quantum state distribution, carrier scattering, and fixed range hopping model, the structural stability and electron transport properties of N-, P-, and As-doped SiC nanowires (N-SiCNWs, P-SiCNWs, and As-SiCNWs) are simulated by using the first principles calculations. The results show that the lattice structure of N-SiCNWs is the most stable in the lattice structures of the above three kinds of doped SiCNWs. At room temperature, for unpassivated SiCNWs, the doping effect of P and As are better than that of N. After passivation, the conductivities of all doped SiCNWs increase by approximately two orders of magnitude. The N-SiCNW has the lowest conductivity. In addition, the N-, P-, As-doped SiCNWs before and after passivation have the same conductivity–temperature characteristics, that is, above room temperature, the conductivity values of the doped SiCNWs all increase with temperature increasing. These results contribute to the electronic application of nanodevices.</jats:p>