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The positioning function of unmanned aerial vehicles (UAVs) is a challenging and fundamental research topic and is the premise for UAVs to realize autonomous navigation. The disappearance of satellite signals makes it challenging to achieve accurate positioning. Thus, visual positioning algorithms based on computer vision have been proposed in recent years and these algorithms have produced good results. However, these algorithms have relatively simple functions and cannot perceive the environment. Their versatility is poor, and mismatching often occurs, which affects the positioning accuracy. Aiming to address the need for integrated target recognition, target matching, and positioning of UAVs, we propose an algorithm that integrates the target recognition, matching, and positioning functions by combining the single-shot multibox detector (SSD) algorithm with the deep feature matching algorithm. This algorithm is based on the idea of pseudo-Siamese networks and the SSD algorithm, introducing a deep feature matching method to directly calculate the correspondence between two images. The main idea is to use the VGG network trained by the SSD target recognition algorithm to extract deep features, without any special training for feature matching. Finally, by sharing neural network weights, the integrated design of target recognition and image-matching localization algorithms is achieved. Mismatches between the real-time and reference images are addressed by introducing the grid-based motion statistics algorithm to optimize the matching result and improve the correct matching efficiency of the target. The University-Release dataset was used to compare and analyze the performance of the proposed algorithm to verify its superiority and feasibility. The results show that the matching accuracy of the PSiamRML algorithm is generally good and that it significantly compensates for changes in the contrast, scale, brightness, blur, deformation, and so on, apart from improving the stability and robustness. Finally, a matching test scenario with aerial images captured by an S1000 six-rotor UAV served to verify the effectiveness and practicability of the PSiamRML algorithm. [ABSTRACT FROM AUTHOR]

Through Euler/Euler large eddy simulation (LES) modeling, it is demonstrated that turbulent dispersion of bubbles can effectively indicate the impact of turbulent eddies on the bubble dynamics, i.e., the bubble oscillation behavior. This finding builds on previous work using the Euler/Lagrange LES modeling approach and leads to a significant improvement in predicting bubble lateral dispersion. Spatially filtered terms were proposed for the subgrid‐scale (SGS) turbulent dispersion and added mass stress force models, with a modification made to the SGS eddy viscosity to reflect bubble turbulent dispersion and oscillations. The proposed model substantially improves the prediction of bubble volume fraction distribution, bubble and liquid phase velocity profiles, the turbulent kinetic energy spectrum, and mass transfer. [ABSTRACT FROM AUTHOR]

Understanding the charge reactions at the semiconductor/cocatalyst interface is of great interest for boosting photoelectrochemical water splitting since the charge transfer to water molecules is the sluggish one. Besides the dopants, porosity, or ion-penetration of the cocatalyst, the crystallinity of the cocatalyst may also influence the charge reactions at the interface. Herein, we prepared amorphous LaNiOx and crystalline La-doped NiO (c-LaNiOx) cocatalysts through photochemical decomposition and ion-exchange of Ni(OH)2 precipitation, respectively. Both lanthanum nickel oxides (LaNiOx) showed considerable improvement of hematite photoanodes. By using electrochemical impedance measurements, we confirmed that the catalyst could store photogenerated charges with reduced transfer resistance and passivate the surface state, resulting in the overall charge transfer rate enhancement. This study may lead to a chance to uncover the kinetic bottleneck with an efficient cocatalyst in well-controlled crystallinity in the future. [ABSTRACT FROM AUTHOR]

This paper proposes the observer-based proportional-integral-derivative control of positive multi-agent systems. First, a positive observer is constructed for the considered multi-agent systems in terms of a matrix decomposition approach. Then, a novel proportional-integral-derivative protocol framework is proposed based on an improved observer. By using copositive Lyapunov function, the positivity and consensus of the multi-agent systems are achieved. The corresponding observer and control protocol gain matrices are designed in terms of linear programming. Moreover, the proposed design is developed for heterogeneous positive multi-agent systems. The main contributions of this paper include the following: (i) A positive observer is constructed to estimate the states of positive multi-agent systems; (ii) A novel observer-based proportional-integral-derivative protocol is designed to handle the consensus problem of positive multi-agent systems; and (iii) The presented conditions are solvable in terms of linear programming and the gain matrices can be constructed based on a matrix decomposition technology. Finally, two illustrative examples are provided to verify the effectiveness of the design. [ABSTRACT FROM AUTHOR]

Long-term visual target tracking of unmanned aerial vehicles (UAVs) is a challenging and basic research topic. In recent years, many visual object tracking methods have been proposed based on the kernel correlation filtering algorithm and achieved good results. These algorithms have good performance in short-term tracking, but when the target is occluded or disappears from view, the original update strategy may lead to tracker drift. Based on these issues, this paper proposes a long-term kernel correlation filtering and speeded-up robust features (KCFSURF) target tracking algorithm for UAVs in the process of long-term target tracking due to target occlusion or loss. The algorithm takes the KCF target tracking algorithm as the framework, introduces the strategy of searching and locating the target after occlusion or loss, and uses the peak side lobe (PSR) ratio to determine whether the target is covered, blocked, or lost. When the target is occluded or lost, the SURF-random sample consensus (RANSAC) target retrieval matching strategy is introduced to rematch the target and select the box. The new samples are input into the KCF algorithm to continue tracking the target. To verify the superiority and feasibility of the proposed algorithm, the OTB100, UAV123, and Temple-color-128 dataset is selected to evaluate and analyze the algorithm quantitatively and qualitatively. The evaluation results show that KCFSURF can rediscover the target after it is blocked or lost, realizing long-term stable target tracking. Finally, the effectiveness of the KCFSURF algorithm is verified in an S500 UAV target tracking scene. [ABSTRACT FROM AUTHOR]

A Z-scheme BiVO 4 /NiCo 2 O 4 (BVO/NCO) heterojunction structure was constructed by modifying optimal ultrathin nickel–cobalt (NiCo 2 O 4) spinel nanosheets on BiVO 4 as an efficient photocatalyst toward water oxidation, which deliver an excellent photocatalytic O 2 evolution performance of 1640.9 μmol∙g−1∙h−1 by reducing the energy barriers and enhancing the separation and transfer of photogenerated carriers. [Display omitted] The sluggish water oxidation process is a severe obstacle for solar-driven water splitting. Therefore, it is imperative to develop a suitable photocatalyst with reduced energy barrier for strong oxidation. In this study, a Z-scheme BiVO 4 /NiCo 2 O 4 (BVO/NCO) heterojunction system was designed by decorating ultrathin nickel–cobalt (NiCo 2 O 4) spinel nanosheets on BiVO 4 as an efficient photocatalyst for water oxidation. The unique structure of the system significantly reduced the energy barrier and improved the oxidation ability of BiVO 4 to efficiently enhance the separation and transfer of the photogenerated carriers. Thus, the photocatalyst delivered an excellent O 2 evolution performance of 1640.9 μmol∙g−1∙h−1 and showed 124% improved efficiency as compared to pristine BiVO 4 and a quantum efficiency of 5.39% at 400 nm for O 2 evolution. Additionally, the theoretical calculations revealed that the formation of *OOH was the rate-determining step for water oxidation. The decoration with NiCo 2 O 4 significantly reduced the energy barrier between *O and *OOH, which eventually improved the photocatalytic performance of BVO/NCO. The results hold great promise for the potential application of spinel-based materials in efficient photocatalytic O 2 evolution and offer fundamental insights into the design of efficient water oxidation heterojunctions. [ABSTRACT FROM AUTHOR]

The effect and mechanism of artemisinin therapy on cerebral ischemia-reperfusion injury (CIRI) was analyzed in this work. 100 healthy male C57BL/6 mice were selected and randomly divided into the sham group (no treatment), CIRI model group (IR), IR + artemisinin posttreatment group (IR + Arte), EX527 + IR group (EX527 + IR), and EX527 + IR + artemisinin posttreatment group (EX527 + IR + Arte), with 20 mice in each group. The cerebral infarct volumes of mice in different groups were measured by the 2,3,5-triphenyltetrazolium chloride (TTC) staining method. The neurological function scores and oxidative stress levels of mice in different groups were measured and compared. In addition, the expressions of silent information regulator 1 (SIRT1), forkhead transcription factor O1 (FOXO1), and p53 protein in brain tissue were detected. The results showed that the contents of reactive oxygen species (ROS) and malondialdehyde (MDA) in the EX527 + IR group and EX527 + IR + Arte group were significantly higher than those in the IR + Arte group (P < 0.05). The expressions of SIRT1 protein in the brain tissue of the IR group and EX527 + IR group were much lower than that of the sham group (P < 0.01); compared with the IR + Arte group, the expression of the X527 + IR group in the brain tissue was greatly reduced (P < 0.05). The expression levels of FOXO1 protein and p53 protein in the brain tissue of mice in the IR group and EX527 + IR group were higher than those in the sham group (P < 0.01). It was concluded that artemisinin treatment can reduce oxidative stress damage and alleviate CIRI through the SIRT1/FOXO1 signaling pathway, thereby achieving neuroprotective effects. [ABSTRACT FROM AUTHOR]

Tall buildings and transmission wires with polygon cross-sections have been shown to have lower drag forces than circular cross-sections. In this study, flow around an 18-sided polygonal cylinder in both stationary and elastic states is numerically investigated. For a stationary polygon cylinder, the effect of Reynolds number (Re) on the drag coefficient (C D) is studied in the range Re = 2.3 × 104-10.6 × 104 and the effect of surface roughness (K / D) on C D is studied at Re = 7.1 × 104. The vortex-induced vibrations (VIV) of an elastically mounted polygon cylinder with m * ζ = 0.185 is studied in the range Re = 1.8 × 103-3.7 × 103 and U r = 3.0-6.0. The results show that the C D of the stationary polygon cylinder is reduced by up to 47 % compared to a circular cylinder and that K / D affects the boundary layer separation and thus C D. The VIV of the polygon cylinder exhibits many features similar to a circular cylinder in the response, phase difference, and wake characteristics though the maximum vibration amplitude is reduced by 11.4 %. Based on the lift coefficient, displacement, and instantaneous frequency, the vibration mechanism of the VIV of the cylinder is discussed. • The drag coefficient of the 18-sided polygon cylinder is reduced by up to 47 % compared to the circular cylinder. • As K / D increases, the C D of the polygon cylinder first decrease, then increase, and finally remains unchanged. • VIV of the polygon cylinder are similar to that of a circular cylinder in responses, phase, and wake characteristics. • The maximum vibration amplitude of the polygon cylinder is reduced by 11.4 % compared to the circular cylinder. [ABSTRACT FROM AUTHOR]

The mutual influence between the bearings of a ship's multisupport shafting makes its installation and alignment very difficult. This article addresses the problem of the calculation of the precise displacement value of each intermediate bearing and proposes a method for fitting the shafting characteristic function by using the GA-BP (genetic algorithm-back propagation) neural network. The neural network uses the intermediate bearing reaction as input to calculate the theoretical height of the bearing, thereby accurately calculating the displacement value. Taking the installation and alignment of a ro-ro ship's propulsion shafting as an application example, a neural network of the ship's shafting is established with training samples based on finite element simulation, and the effect of network training is discussed. The accuracy of the method is verified by a comparative analysis with the measured data of the ship's shafting. The calculation results of this method are used as a guide for the installation and alignment of the ship's shafting and have passed the delivery inspection of the classification society. [ABSTRACT FROM AUTHOR]

The guaranteed‐performance consensus tracking (GPCT) for non‐linear multi‐agent systems (MASs) with switching communication topologies is presented. Different from the existing work, the non‐linear range of one‐sided Lipschitz non‐linear MASs is wider than the Lipschitz ones, and the upper bound of the tracking performance is given while achieving the consensus tracking. First, a guaranteed‐performance tracking control protocol is proposed, where consensus tracking regulation performance is involved. Then, by the linear matrix inequality (LMI), sufficient conditions are provided to achieve the GPCT under the one‐sided Lipschitz and quadratic inner bounded conditions. It is worth noting that a special LMI structure is directly constructed by introducing these two conditions to simplify the complexity of the derivation. Finally, two simulation examples are provided to demonstrate the effectiveness of the proposed results. [ABSTRACT FROM AUTHOR]

The most common approach to solving blade element momentum (BEM) equations is through fixed point method. The fixed point method can provide reliable solutions with high precision, yet the robustness of the method has been challenged when infrequent failures of converging to a physical solution are found for some design space. Though the lack of robustness is alleviated by applying two improved algorithms, their shortcomings should not be of an understatement. Ning's method can result in a converged yet nonphysical solution, and Sun's method decreases the computational efficiency remarkably. To overcome these setbacks, a new algorithm has been proposed in this paper. A clear classification of a wind turbine operating states has been given first to correct the thrust relation for a > 1, followed by discussions of three failure cases encountered during solving BEM equations. Then, the new algorithm with three major modifications has been introduced and explained. The test of Section 4 reveals that the decreasing rf technique has a positive effect on improving the robustness. Besides, the first two tests in Section 5 prove that the new thrust equation can greatly enhance the robustness, and Aitken's squared process can significantly strengthen the efficiency. The results show that all three modifications contribute to offering a new FPA with high robustness and satisfactory computing efficiency, which serves as the best option for solving the BEM equations. [ABSTRACT FROM AUTHOR]

In the current article, the influence of titanium on the hot ductility of peritectic-microalloyed steels, in the temperature range 600°C to 950°C, was investigated by tensile testing. The morphology of the fracture and the behaviour of precipitates, inclusions and microstructures near the fracture surface were observed and discussed. It was found that within the test temperature range, the reduction in area values of titanium-bearing steels were almost greater than 40%, which were much larger than those of titanium-free steels. This improvement was due to the formation of (TixNb1-x)(CyN1-y) precipitates and titanium-aluminium oxides with high titanium content that could act as the nucleation sites for dimples to promote the occurrence of ductile fracture. In addition, the austenite grain was refined and more uniform in size. The thickness together with the maintain temperature range of the ferrite films which distribute only along austenite grain boundaries were reduced. [ABSTRACT FROM AUTHOR]

• The modified SGS-TDF model was proposed and implemented in Euler/Euler LES for bubbly flow. • LES coupled with the modified SGS-TDF model can simulate and mimic bubble oscillation. • κ−5/3 and κ−3 scaling laws were recovered in Euler/Euler LES modelled turbulent kinetic energy spectrum. • A correlation of vorticity indicator Q and the local bubble volume fraction was proposed. It has now been recognised and generally accepted that turbulent dispersion may be modelled using the time average of the fluctuating part of the interphase momentum, employing the drag the Favre averaged drag model for turbulent dispersion in Eulerian multi-phase flows. As the turbulent eddies in the surrounding of bubbles interact strongly with the bubbles in bubbly flow, the bubble trajectories and bubble oscillation take place accordingly as the consequence of continuous deformation of the bubble surfaces. When using large eddy simulation for modelling bubbly flow, the sub-grid scale (SGS) filtered velocity fluctuations of liquid phase can be interpreted as many small eddies that may act on the surface of bubbles, consequently giving rise to bubble shape variations and the dispersion of bubbles. This study employs Euler/Euler large-eddy simulation (LES) modelling to demonstrate that the turbulent dispersion force model can be used to effectively indicate the influence of turbulent eddies on bubble dynamics, in particular the bubble cluster oscillations, which leads to remarkable improvements in the prediction of bubble lateral dispersion behaviour. The use of spatial filtering to model the SGS bubble dispersion is proposed with a modification on SGS eddy viscosity to reflect turbulent dispersion due to bubble induced turbulence. The results of the time-averaged LES modelled bubble velocities and bubble volume fraction profiles are in good agreement with the experimental data while the turbulent kinetic energy spectrum obtained at different locations on the centreline of the bubble column still exhibits the conventional −5/3 scaling for shear induced turbulence and a −3 scaling for bubble induced turbulence. [ABSTRACT FROM AUTHOR]

To reduce the computation required in determining the proper scale of salient object, a fast visual saliency based on multi‐scale difference of Gaussians fusion in frequency domain (MDF) is proposed. First, based on the phenomenon that the foreground energy is highlighted and densely distributes on certain band of spectrum, the scale coefficients of foreground in an image can be literately approximated on the amplitude spectrum. Next, relying on the linear integration property of Fourier transform, the feature spectrum is obtained through the weighted infinite integral of difference of Gaussian feature maps with respect to the scale of object. Then, the saliency of each channel is obtained from feature spectrum by the inverse Fourier transform and scale filtering. Finally, through the channel integration, the MDF saliency map is obtained. Experiments on Li‐Jian data set demonstrate that combined with most appropriate colour space and scale filter, MDF achieves obvious acceleration (5.4 times faster than frequency domain analysis and spatial information) while getting desired accuracy (area under the curve, 0.8814 at Li‐Jian data set), which achieves the best accuracy efficiency trade‐off. [ABSTRACT FROM AUTHOR]

To reduce the computation required in determining the proper scale of salient object, a fast visual saliency based on multi-scale difference of Gaussians fusion in frequency domain (MDF) is proposed. First, based on the phenomenon that the foreground energy is highlighted and densely distributes on certain band of spectrum, the scale coefficients of foreground in an image can be literately approximated on the amplitude spectrum. Next, relying on the linear integration property of Fourier transform, the feature spectrum is obtained through the weighted infinite integral of difference of Gaussian feature maps with respect to the scale of object. Then, the saliency of each channel is obtained from feature spectrum by the inverse Fourier transform and scale filtering. Finally, through the channel integration, the MDF saliency map is obtained. Experiments on Li-Jian data set demonstrate that combined with most appropriate colour space and scale filter, MDF achieves obvious acceleration (5.4 times faster than frequency domain analysis and spatial information) while getting desired accuracy (area under the curve, 0.8814 at Li-Jian data set), which achieves the best accuracy efficiency trade-off. [ABSTRACT FROM AUTHOR]

This paper presents a deep learning algorithm for tomographic reconstruction (GANrec). The algorithm uses a generative adversarial network (GAN) to solve the inverse of the Radon transform directly. It works for independent sinograms without additional training steps. The GAN has been developed to fit the input sinogram with the model sinogram generated from the predicted reconstruction. Good quality reconstructions can be obtained during the minimization of the fitting errors. The reconstruction is a self‐training procedure based on the physics model, instead of on training data. The algorithm showed significant improvements in the reconstruction accuracy, especially for missing‐wedge tomography acquired at less than 180° rotational range. It was also validated by reconstructing a missing‐wedge X‐ray ptychographic tomography (PXCT) data set of a macroporous zeolite particle, for which only 51 projections over 70° could be collected. The GANrec recovered the 3D pore structure with reasonable quality for further analysis. This reconstruction concept can work universally for most of the ill‐posed inverse problems if the forward model is well defined, such as phase retrieval of in‐line phase‐contrast imaging. [ABSTRACT FROM AUTHOR]

• Shear controllable synthesis of particles realized by using a lobed inner cylinder Taylor-Couette reactor. • The use of lobed inner cylinder enhances the shear through the local impinging jet flow. • Synthesised particle size strongly correlates with the local turbulent dissipation rate. A novel lobed inner cylinder assembled in Taylor-Couette flow reactor (LTC) has been adopted to synthesize barium sulfate particles. The fluid dynamics that affects synthesis of particles using both the LTC and the classical Taylor-Couette flow reactor (CTC) was investigated through CFD modelling and experiments. The results have demonstrated that the Taylor vortices and turbulence induced shear rate distribution in the reactors have a significant influence on the final particle size distribution. The narrower shear rate distribution in the LTC is beneficial to the synthesis of particles with smaller size. The local turbulence intensification in the intra-Taylor vortices in the LTC effectively reduces the low shear strain regions. A strong correlation between the synthesized particle size and the local turbulent dissipation rate is existing. Shear induced by small turbulent eddies can inhibit particle growth. The LTC can be used for effectively shear controllable synthesis of particles. [ABSTRACT FROM AUTHOR]

Aims: Our study aimed to investigate the expression and prognostic role of homeobox C6 (HOXC6) in prostate cancer (PCa). Methods: Relative expression of HOXC6 at mRNA and protein levels in tissues and cell lines of PCa were measured using quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot analysis, respectively. Association between HOXC6 expression and clinical factors was analyzed by Chi-square test. HOXC6 effects on the proliferation, invasion and metastasis of PCa cells were severally examined through CCK-8 and transwell assays. Results: Relative expressions of HOXC6 at mRNA and protein levels were obviously higher in both PCa tissues and cells than in adjacent non-cancerous tissues and normal human prostate epithelial cells (p <.05). Chi-square test demonstrated that high expression of HOXC6 was significantly associated with PSA concentration, Gleason score and TNM stage (p <.05). The down-regulation of HOCX6 remarkably inhibited the proliferation, migration and invasion of PCa cells. Kaplan-Meier analysis showed that patients with high HOXC6 expression had shorter overall survival than those with low HOXC6 expression (log rank test, p <.001). Conclusion: Up-regulated HOXC6, in PCa patients, could not only participate in the progression of PCa but also function as an independent prognostic marker for the cancer. [ABSTRACT FROM AUTHOR]

Increasing evidence has shown that long non-coding RNAs (lncRNAs) serve a critical role in tumor progression. The lncRNA protein disulfide isomerase family A member 3 pseudogene 1 (PDIA3P) is associated with the progression of oral squamous cell carcinoma and multiple myeloma. However, the roles of lncRNA PDIA3P in non-small cell lung cancer (NSCLC) remain unknown. In the present study, it was demonstrated that lncRNA PDIAP3 expression was significantly increased in patients with NSCLC, particularly in patients with an advanced Tumor-Node-Metastasis stages and lymph-node metastasis. The Gene Expression Profiling Interactive Analysis database revealed that patients with NSCLC with high lncRNA PDIA3P expression had a poorer disease-free survival rate. Furthermore, functional assays suggested that PDIA3P inhibition significantly suppressed the proliferation and invasion of NSCLC cells in vitro and reduced tumor growth in vivo. In addition, lncRNA PDIA3P enhanced the activity of the Wnt/β-catenin pathway in progression of NSCLC. The present study showed that lncRNA PDIA3P promoted NSCLC progression by regulating Wnt/β-catenin signaling, highlighting a potential therapeutic target for treating patients with NSCLC treatment. [ABSTRACT FROM AUTHOR]

The preparation of nanoparticles can be conducted in a fast way by intensifying the micromixing due to the enhanced turbulence in an impinging jet Reactor (IJR) where the two linear liquid jets collide with high velocity to diminish the segregation. However, the micromixing is significantly affected by the occurrence of the stagnant region which may partially choke the reaction chamber. By imposing the ultrasound to the IJR, micro-scale turbulent eddies generated as the result of collapse of ultrasonically generated micro cavitation bubbles may generate a strong local shear. Such micro-scale turbulent vortices exert shear on the interface between the particles and surrounding fluid, resulting in uniform particle morphology and high surface area for chemical reaction. The paper aims to optimize the ultrasonic intensification effect on synthesis of nano-sized particles with desired homogeneity, reveal the governing mechanisms and present a kinetic model to describe the multiphase flow dynamics in the IJR. Except for the experimental method, numerical method was also used to demonstrate the impact of fluid dynamics on particle synthesis. Unlabelled Image • The use of the impinging jet reactor (IJR) to intensify the micro-mixing. • Micro-scale turbulent eddies exert shear to shape the particle interface. • Ultrasonic intensification assists for synthesis of nano-sized homogenous particles. • Increase in local turbulent dissipation rate is beneficial to the controllable synthesis. [ABSTRACT FROM AUTHOR]

• Considering the effects of bubble induced turbulence in the bubble breakage model. • κ −3 scaling has been identified on bubble induced turbulence kinetic energy spectrum. • Mean turbulent velocity and number density of turbulent eddies have been modified. • Influence of characteristic length scale on daughter bubble PDF is illustrated. • Effect of eddy-bubble contact on mass transfer in the bubble column is demonstrated. A quantitative description of the interaction between the turbulence eddies and bubble groups is crucial for the prediction of the bubble size distribution in bubble columns when adopting the population balance model (PBM) to estimate the heat and mass transfer across the interfaces between bubbles and carrier liquid. The majority of breakage kernels that are currently adopted focus on the shear turbulence in the liquid phase and model the kinetic energy contained in the arrival eddies that hit the bubbles by using the classical single-phase turbulence Kolmogorov −5/3 scaling law. In bubble columns, eddies that collide with bubbles and cause the bubble breakage are mainly generated by bubble-induced turbulence (BIT). The present work focuses on the influence of κ −3 scaling of the bubble-induced turbulence energy spectrum on the bubble breakage due to the eddy-bubble collision in bubble columns. A modified breakage model accounting for the bubble-induced turbulence is proposed. The proposed breakage model considers the mean turbulent velocity of eddies under the influence of bubble-induced turbulence and the characteristic wavenumber/length scale that corresponds to BIT. A comparison of the simulation results with the experimental data clearly demonstrate that the modified breakage model appropriately describes the bubble breakage events occurring under the influence of bubble-induced turbulence in bubble columns. It is also shown that the interaction of bubbles with the bubble-induced turbulence eddies has an impact on prediction of the mass transfer in bubble column flows. [ABSTRACT FROM AUTHOR]

The elastic vibration response of coat layered semiconducting microcantilevers, which were excited with a frequency-modulated pump laser and detected with another probe beam, was studied experimentally and theoretically in this paper. The photothermal vibration frequency spectra were measured and analyzed for a set of microcantilevers with different coating thickness at the region near the first resonant frequency. Also the vibrations of microcantilevers were calculated using coupled carrier dispersion, thermal wave and elastic wave equations. The results showed that the experimental results had a good agreement with the theoretical ones. [ABSTRACT FROM AUTHOR]

Abstract In traditional hydrodynamic theories for ionic fluids, conservation of mass and linear momentum is not properly taken care of. In this paper, we develop hydrodynamic theories for viscous, ionic fluids of N ionic species enforcing mass and momentum conservation as well as considering the size effect of the ionic particles. The theories developed are quasi-incompressible in that the mass-average velocity is no longer divergence-free whenever there exists variability in densities of the fluid components, and the theories are dissipative. We present several ways to derive the transport equations for the ions, which lead to different rates of energy dissipation. The theories can be formulated in either number densities, volume fractions or mass densities of the ionic fluid components. We show that the theory with the Cahn-Hilliard transport equation for ionic species reduces to the classical Poisson-Nernst-Planck (PNP) model with the size effect for ionic fluids when the densities of the fluid components are equal and the entropy of the solvent is neglected. It further reduces to the PNP model when the size effect is neglected. A linear stability analysis of the model together with two of its limits, which are the extended PNP model (EPNP defined in the text) and the classical PNP model (CPNP) with the finite size effect, on a constant state and a comparison among the three models in 1D space are presented to highlight the similarity and the departure of this model from the EPNP and the CPNP model. Highlights • A quasi-incompressible hydrodynamic model of N-species ionic fluid flows is presented. • The model reduces to well-known ionic fluid models in selected time and length scales. • A three-component model is analyzed to showcase effects of quasi-incompressibility. [ABSTRACT FROM AUTHOR]

Two classes of thermodynamically consistent hydrodynamic phase field models have been developed for binary fluid mixtures of incompressible viscous fluids of possibly different densities and viscosities. One is quasi-incompressible, while the other is incompressible. For the same binary fluid mixture of two incompressible viscous fluid components, which one is more appropriate? To answer this question, we conduct a comparative study in this paper. First, we visit their derivation, conservation and energy dissipation properties and show that the quasi-incompressible model conserves both mass and linear momentum, while the incompressible one does not. We then show that the quasi-incompressible model is sensitive to the density deviation of the fluid components, while the incompressible model is not in a linear stability analysis. Second, we conduct a numerical investigation on coarsening or coalescent dynamics of protuberances using the two models. We find that they can predict quite different transient dynamics depending on the initial conditions and the density difference although they predict essentially the same quasi-steady results in some cases. This study thus cast a doubt on the applicability of the incompressible model to describe dynamics of binary mixtures of two incompressible viscous fluids especially when the two fluid components have a large density deviation. [ABSTRACT FROM AUTHOR]

A unique correlative approach for automated segmentation of large 3D nanotomography datasets obtained using Transmission X-ray Microscopy (TXM) in an Al-Cu alloy has been introduced. Automated segmentation using a Convolutional Neural Network (CNN) architecture based on a deep learning approach was employed. This extremely versatile technique is capable of emulating the manual segmentation process effectively. Coupling this technique with post-scanning SEM imaging ensured precise estimation of 3D morphological parameters from nanotomography. The segmentation process as well as subsequent analysis was expedited by several orders of magnitude. Quantitative comparison between segmentation performed manually and using the CNN architecture established the accuracy of this automated technique. Its ability to robustly process ultra-large volumes of data in relatively small time frames can exponentially accelerate tomographic data analysis, possibly opening up novel avenues for performing 4D characterization experiments with finer time steps. [ABSTRACT FROM AUTHOR]

In the current article, a method based on analysis of the microstructure combined with numerical simulation of the temperature field of a continuous casting slab is proposed to eliminate the transverse cracks occurred in slab corners. The microstructures near the cracks will be varied as the phase‐transformation conditions change. Thus, the cracking temperature range can be effectively estimated by analyzing the microstructures near the cracks. The different behaviors of microstructures near cracks in three conditions are presented and discussed. These behaviors include the following: the decarburization layer is symmetrically distributed on both sides of the cracks; the microstructures are refined near the cracks; the cracks “open” the ferrite along the austenite grain boundaries, which results in the ferrite being symmetrically distributed on both sides of the cracks. The variation of the slab corner temperature during a continuous casting process is calculated and discussed. Then, a secondary cooling adjustment scheme is proposed to eliminate the occurrence of transverse corner cracks on the slab surface. Results from industrial practice show that the method can effectively avoid the generation of slab surface cracks without damage to the internal quality of the slab. The method can also be applied to other studies of crack control. [ABSTRACT FROM AUTHOR]

Abstract: Micro‐ and nanometer‐sized metal–organic frameworks (MOFs) materials have attracted great attention due to their unique properties and various potential applications in photonics, electronics, high‐density storage, chemo‐, and biosensors. The study of these materials supplies insight into how the crystal structure, molecular components, and micro‐/nanoscale effects can influence the performance of inorganic–organic hybrid materials. In this Minireview article, we introduce recent breakthroughs in the controlled synthesis of MOF micro‐/nanomaterials with specific structures and compositions, the tunable photonic and electronic properties of which would provide a novel platform for multifunctional applications. Firstly, the design strategies for MOFs based on self‐assembly and crystal engineering principles are introduced. Attention is then focused on the methods of fabrication of low‐dimensional MOF micro‐/nanostructures. Their new applications including two‐photon excited fluorescence, multi‐photon pumped lasing, optical waveguides, nonlinear optical (NLO), and field‐effect transistors are also outlined. Finally, we briefly discuss perspectives on the further development of these hybrid crystalline micro‐/nanomaterials. [ABSTRACT FROM AUTHOR]

The thermal characteristics of Cu-based catalysts for CO 2 utilization towards the synthesis of methanol were analysed and discussed in this study. The preparation process were varied by adopting ultrasonic irradiation at various impulses for the co-precipitation route and also, by introducing ZnO promoters using the solid-state reaction route. Prepared catalysts were characterised using XRD, TPR, TPD, SEM, BET and TG-DTA-DSC. In addition, the CO 2 conversion and CH 3 OH selectivity of these samples were assessed. Calcination of the catalysts facilitated the interaction of the Cu catalyst with the respective support bolstering the thermal stability of the catalysts. The characterisation analysis clearly reveals that the thermal performance of the catalysts was directly related to the sonication impulse and heating rate. Surface morphology and chemistry was enhanced with the aid of sonication and introduction of promoters. However, the impact of the promoter outweighs that of the sonication process. CO 2 conversion and methanol selectivity showed a significant improvement with a 270% increase in methanol yield. [ABSTRACT FROM AUTHOR]

Formation of fluidised bubbles in a fluidised bed has significant impact on the design and scale-up of the bubbling fluidised bed. To fully understand bubble motions in the fluidised bed, fluidised bubble dynamics in a gas-solid fluidised bed is investigated using CFD-DEM numerical simulation. To reveal the mechanism of bubble formation in the bubbling fluidised bed, the time autocorrelation approach is adopted to identify bubble occurrence at different bed height positions. A non-dimensional correlation accounting for the effect of local velocity field on the bubble size, which is obtained by modifying the Darton's model, is proposed for predicting the bubble size at given bed height positions. The non-dimensional correlation for predicting the size of the fluidised bubbles at various given bed height positions is obtained by regression based on the CFD-DEM modelling results. The simulation results indicate that small bubbles with high passing frequency dominate in the bottom region of the fluidised bed, while large bubbles are formed in the zone close to the free surface of the fluidised bed. The probability of the appearance of large bubbles increases as the height measured from the bottom of the fluidised bed increases, which may be attributed to the coalescence of small bubbles; this is also reasonably consistent with the results predicted using the Darton's model and experimental observations. It was observed that the sizes of the fluidised bubbles at the given height positions correlate with the local dynamic parameters characterised by the Reynolds number and the dimensionless height ratio. [ABSTRACT FROM AUTHOR]

[Display omitted] • Mixing performance at both a macroscale and microscale was assessed by CFD method. • Simulation of turbulent reacting flow was realized by using DQMOM-IEM model. • The adoption of ultrasound can improve both the global and local mixing. • Effective mixing still exists even under a laminar flow condition. Mixing performance for a consecutive competing reaction system has been investigated in a swirling vortex flow reactor (SVFR). The direct quadrature method of moments combined with the interaction by exchange with the mean (DQMOM-IEM) method was employed to model such reacting flows. This type of reactors is able to generate a strong swirling flow with a great shear gradient in the radial direction. Firstly, mixing at both macroscale and microscale was assessed by mean mixture fraction and its variance, respectively. It is found that macromixing can be rapidly achieved throughout the whole reactor chamber due to its swirling feature. However, micromixing estimated by Bachelor length scale is sensitive to turbulence. Moreover, the additional introduction of ultrasound irradiation can significantly improve the mixing uniformity, namely, free of any stagnant zone presented in the reactor chamber on a macroscale, and little variance deviating from the mean environment value can be observed on a microscale. Secondly, reaction progress variable and the reactant conversion serve as indicators for the occurrence of side reaction. It is found that strong turbulence and a relatively fast micromixing process compared to chemical reaction can greatly reduce the presence of by-product, which will then provide homogenous environment for particle precipitation. Moreover, due to the generation of cavitation bubbles and their subsequent collapse, ultrasound irradiation can further intensify turbulence, creating rather even environment for chemical reactions. Low conversion rate was observed and little by-products were generated consequently. Therefore, it is suggested that the SVFR especially intensified by ultrasound irradiation has the ability to provide efficient mixing performance for the fine-particle synthesis process. [ABSTRACT FROM AUTHOR]

Lanthanide metal-organic frameworks (Ln-MOFs) have received much attention owing to their structural tunability and widely photofunctional applications. However, successful examples of Ln-MOFs with well-defined photonic performances at micro-/nanometer size are still quite limited. Herein, self-assemblies of 1,3,5-benzenetricarboxylic acid (BTC) and lanthanide ions afford isostructural crystalline Ln-MOFs. Tb-BTC, Eu@Tb-BTC, and Eu-BTC have 1D microrod morphologies, high photoluminescence (PL) quantum yields, and different emission colors (green, orange, and red). Spatially PL resolved spectra confirm that Ln-MOF microrods exhibit an optical waveguide effect with low waveguide loss coefficient (0.012≈0.033 dB μm−1) during propagation. Furthermore, these microrods feature both linear and chiral polarized photoemission with high anisotropy. [ABSTRACT FROM AUTHOR]

Lanthanide metal-organic frameworks (Ln-MOFs) have received much attention owing to their structural tunability and widely photofunctional applications. However, successful examples of Ln-MOFs with well-defined photonic performances at micro-/nanometer size are still quite limited. Herein, self-assemblies of 1,3,5-benzenetricarboxylic acid (BTC) and lanthanide ions afford isostructural crystalline Ln-MOFs. Tb-BTC, Eu@Tb-BTC, and Eu-BTC have 1D microrod morphologies, high photoluminescence (PL) quantum yields, and different emission colors (green, orange, and red). Spatially PL resolved spectra confirm that Ln-MOF microrods exhibit an optical waveguide effect with low waveguide loss coefficient (0.012≈0.033 dB μm−1) during propagation. Furthermore, these microrods feature both linear and chiral polarized photoemission with high anisotropy. [ABSTRACT FROM AUTHOR]

Bubble fluidisation in the fuel reactor adopted in chemical looping combustion (CLC) has a siganificant impact on the operation efficiency. Although a variety of numerical modellings of fluid dynamic process in the fuel reactors have been conducted, studies on predicting the fluidised bubble behaviours in the cylindrical fuel reactor where the effect of the heterogeneous reaction is also considered are still lacking. In this paper, the use of correlations of fluid dynamic parameters to characterise the fluidised bubble formation in the fuel reactor was proposed. A correlation parameter relating the time-dependent fluidised bubbles to the local eddies was introduced by correlating the local gas velocity fluctuation with the pressure fluctuation. The existence of a strong correlation between the concentration of gaseous reactants or products and local vortices was also demonstrated. Three-dimensional multiphase CFD model coupled with the heterogenoeous reaction kinetics was employed to study the details of CLC process in the fuel reactor. The results clearly indicated that the approach used in the present work can effectively monitor the formation of fluidised bubble in the dense fluidised bed during the heterogeneous reaction and may be used in the CLC as an indicator for monitoring the reduction rate as the locally embedded large eddies are strongly associated with the fluidised bubble occurrance. [ABSTRACT FROM AUTHOR]

This paper presents an algorithm to calibrate the center-of-rotation for X-ray tomography by using a machine learning approach, the Convolutional Neural Network (CNN). The algorithm shows excellent accuracy from the evaluation of synthetic data with various noise ratios. It is further validated with experimental data of four different shale samples measured at the Advanced Photon Source and at the Swiss Light Source. The results are as good as those determined by visual inspection and show better robustness than conventional methods. CNN has also great potential for reducing or removing other artifacts caused by instrument instability, detector non-linearity, etc. An open-source toolbox, which integrates the CNN methods described in this paper, is freely available through GitHub at tomography/xlearn and can be easily integrated into existing computational pipelines available at various synchrotron facilities. Source code, documentation and information on how to contribute are also provided. [ABSTRACT FROM AUTHOR]

Zeolitic imidazolate framework-8 directly exhibits unexpected white-light emission and near-infrared (NIR) phosphorescence, due to the host–guest interaction and the alternation of electron-density distribution, as confirmed by both experimental and computational studies. [ABSTRACT FROM AUTHOR]

CO 2 absorption by a confined free film has been investigated using the CFD approach. Particular attention focuses on the relationship between mass transfer and flow behaviour of the confined free film. Simulation results show that the average K L value grows 26.9% for the open window region and 17.4% for the lower-wall region, respectively, in comparison to the values in the upper-wall region, and the average K L value of confined free film along the flow direction is about 19.2% higher than the value of wall-bounded film, which affirms that the use of an open window can significantly enhance mass transfer performance and such effect also has impact on the entire regions. It was revealed that there exist two types of vortices inside the film, inner vortices and interfacial vortices. In addition, a correlation coefficient R Ωc is proposed to provide a quantitative measure to characterise the relationship between the local mass concentration profile and vorticity distribution of confined free film. Simulation shows that the average value of R Ωc is 0.93, indicating that the two parameters are highly correlated. Furthermore, the cause of lower correlation coefficient value is discussed. [ABSTRACT FROM AUTHOR]

Two novel luminescent three-dimensional coordination polymers [Eu2(tpphz)(oba)3]·nH2O (n = 5.5 for 1, n = 3.5 for 2; H2oba = 4,4′-dicarboxydiphenyl ether) have been hydrothermally synthesized by in situ generation of tetrapyrido[3,2-a:2′,3′-c:3′′,2′′-h:2′′′,3′′′-j]phenazine (tpphz) ligand from 2-(4-pyridine)-imidazo-[4,5-f]1,10-phenanthroline precursor. Both complexes are rare examples of eight-connected self-penetrating networks. The porous nature of the structures is further supported by gas adsorption measurements. [ABSTRACT FROM AUTHOR]

• E-E LES modelling on three CO 2 chemisorption cases in bubble columns was conducted. • Modified SGS turbulent dispersion (TDF) and added mass stress (AMS) models proposed. • Impacts of the SGS-TDF and SGS-AMS terms on the interfacial mass transfer were assessed. • Scaling laws of turbulent kinetic energy and species concentration spectra were discussed. It has been generally recognised that the turbulent dispersion force plays an important role in interphase momentum transfer. However, the effect of the added mass stress on the momentum and mass transfer in bubble column bubbly flow has not been addressed appropriately. As the turbulent eddies in the surroundings of bubbles interact strongly with the rising bubbles in bubble column bubbly flow, such interactions will bring out the change of interfacial areas between the bubbles and carrier fluid, consequently leading to changes in the interfacial mass transfer. When employing large eddy simulation for modelling bubbly flow coupled with the chemisorption process, the SGS filtered velocity fluctuations of liquid phase can be interpreted as the turbulent eddies that continuously hit the surfaces of bubbles, causing bubble deformation and the variation of bubble interfacial areas, which give rise to the turbulent dispersion and added mass stress forces. The present study will demonstrate through Euler/Euler large-eddy simulations (LES) modelling that by considering the turbulent dispersion force (SGS-TDF) and added mass stress (SGS-AMS), the bubble dynamics and mass transfer under the chemisorption conditions can be better indicated, which leads to remarkable improvements in the prediction of bubble lateral dispersion and the interfacial mass transfer. The turbulent dispersion and added mass stress related to the spatially filtering were proposed with a modification on SGS eddy viscosity to reflect turbulent dispersion due to bubble-induced turbulence. A comprehensive assessment of the effects of these additional filtered stress terms on the time-averaged velocity and bubble volume fraction profiles, flow patterns, mass transfer and the pH variation during CO 2 chemisorption and the turbulent kinetic energy and species concentration spectra was conducted. [ABSTRACT FROM AUTHOR]

Advanced hetero-nanostructured materials for electrochemical devices, such as Li-ion batteries (LiBs), dramatically depend on each functional component and their interfaces to transport and storage charges, where the bottleneck is the sluggish one in series. In this work, we prepare Ni(OH) 2 @C hybrids through a continuous feeding in reflux and followed by a hydrothermal treatment. The as-prepared Ni(OH) 2 @C can be further converted into NiO@C hybrids after thermal annealing. As a control, Ni(OH) 2 &C and NiO&C nanocomposites have also been prepared. Peakforce Tuna measurement shows the conductivity of the NiO@C hybrids is higher than that of NiO&C composites in nanoscale. To further investigate the quality of the interface, 100 charge/discharge cycles of the hybrids are performed in LiBs. The capacity retention of hybrid materials has significantly improved than the simple carbon composites. The enhancement of the electrochemical performance is attributed to the better electric conductivity and smaller charge transfer impedance and strong covalent interface between nickel species and carbon spheres obtained through the controlled seeded deposition. [ABSTRACT FROM AUTHOR]

Consensus problems for linear multi-agent systems with time-varying interaction topologies and multiple time-varying delays are transformed into asymptotic stability problems and necessary and sufficient conditions for consensus are given. Furthermore, several corollaries are proposed to show specific consensus criteria for different cases. Moreover, applications of theoretical results to the spacecraft formation flight are investigated. [ABSTRACT FROM AUTHOR]

A Taylor–Couette (TC) reactor has been considered as a promising technology to produce uniform ultra-fine particles with controlled morphology and size because of its rather narrow shear rate distribution in comparison to a conventional stirred tank. However, small particles in the TC reactor are likely entrapped by the Taylor vortices and concentrated more in the core of the vortices, thus having an adverse or a positive impact on producing the uniformly fine particles. To mitigate this disadvantage, one approach is to adopt an inner cylinder with a variable cross-section through the proper design to obtain a non-constant gap between the inner and outer cylinders in the TC reactor. This study investigates the use of specific profiles of the cross section for the inner cylinder to deform the Taylor vortices, effectively reducing the regions of low velocity and shear rate in the TC reactor. The profiles are composed of a series of curves. The flow patterns and shear rate distributions in the modified TC reactors were investigated using CFD modelling. The sliding mesh method and the Reynolds stress model were employed in the simulation to account for highly turbulent rotating flows. The simulated results compared with those for the classical TC reactor clearly indicate that the regions of low shear rate are effectively reduced in the modified TC reactors because the Taylor vortices occurring in the gap becomes temporal-periodic with respect to the stationary outer cylinder. The obtained shear rate distributions are remarkably narrower than those of the classical TC reactor. It was revealed that the curvature of curves for the cross-section profiles can significantly affect the shear rate distributions, and there exists an optimal profile for the inner cylinder cross-section. [ABSTRACT FROM AUTHOR]

Infrared and visible image fusion makes full use of abundant detailed information of multi-sensor to help people better understand various scenarios. In this paper, a novel method of infrared and visible image fusion based on multi-level saliency integration is proposed. First, the background image of each sub-image is reconstructed by the means of Bessel interpolation after the quadtree decomposition on the infrared image, and the difference saliency is extracted by the difference between the source infrared image and the estimated background. Then, the sparse saliency is calculated from the infrared image using the sparsity of salient objects and the low rank of background. Third, the multi-scale saliency is obtained by Laplacian transformation between the visible image and infrared image to preserve the detailed information. At last, the fusion strategy based on the adaptive weighting coefficient is present to get more natural fusion results. Experimental results on 20 pairs of source images demonstrate that the proposed method outperforms the other state-of-the-art methods in terms of subjective vision and objective evaluation. [ABSTRACT FROM AUTHOR]

Heterogeneous scene matching is a key technology in the field of computer vision. The image rotation problem is popular and difficult in the field of heterogeneous scene matching. In this paper, a heterogeneous scene matching method based on the gradient direction distribution field is proposed, and distributed field theory is introduced into heterogeneous scene matching for the first time. First, the distribution field of the gradient direction is constructed and fuzzified, and then the effective regions are selected. Then, the distribution field of the main direction is defined to solve the matching errors due to the existence of rotational transformations between heterogeneous source images. Third, the chi-square distance is introduced as a similarity measure. Finally, the hill-climbing method search strategy, which greatly improves the efficiency of the algorithm, is adopted. Experimental results on 8 pairs of infrared and visible heterogeneous images demonstrate that the proposed method outperforms the other state-of-the-art region-based matching methods in terms of the robustness, accuracy, and real-time performance. [ABSTRACT FROM AUTHOR]

This paper aims at developing a nonlinear mathematical model for the unsteady wake galloping forces (UWGF) acting on a circular cylinder in the wake of a fixed identical circular cylinder, which is always neglected in quasi-steady analysis. Numerical simulations are conducted to obtain the synchronous unsteady aerodynamic lift forces and displacements of wake galloping at Reynolds numbers (Re) of 1640–8420. The downstream cylinder is free to vibrate in the cross-flow direction with a mass-damping m*ζ = 0.267. The spacing ratio is fixed at L/D = 4 (where L is the center-to-center distance between the cylinders and D is the cylinder diameter). The UWGF model is built by combining the self-excited force and the vortex-induced force based on the spectra of the aerodynamic lift forces. Using an energy equivalent principle, the self-excited force can be divided into three parts: aerodynamic damping terms, aerodynamic stiffness terms and pure force terms. The identified aerodynamic parameters show that the aerodynamic damping terms are key factors determining the stable amplitude of wake galloping. The vortex-induced forces trigger an initial displacement to excite vibration in the early stage and have no influence on the stable amplitude. The proposed UWGF model is verified by experimental results and can calculate wake galloping responses better than the quasi-steady theory. • The UWGF model is built by combining the self-excited force and the vortex-induced force based on the spectra of lift forces. • The aerodynamic damping terms are key parameters determining the amplitude of wake galloping. • The proposed UWGF model can be easily applied and the impact of each model term on the responses of wake galloping can be figured out clearly. [ABSTRACT FROM AUTHOR]

In this paper, the authors employ Lyapunov stability theory, and the M-matrix, H-matrix, and linear matrix inequality (LMI) techniques and variational methods to obtain the LMI-based stochastically exponential robust stability criterion for discrete and distributed time-delays Markovian jumping reaction-diffusion integro-differential equations with uncertain parameters, whose background of physics and engineering is bidirecional associative memory (BAM) neural networks. It is worth mentioning that an LMI-based stability criterion can easily be computed by the Matlab toolbox which has high efficiency and other advantages in large-scale engineering calculations. Since using the M-matrix and H-matrix methods is not easy in obtaining the LMI criterion conditions, the methods employed in this paper improve those of previous related literature to some extent. Moreover, a numerical example is presented to illustrate the effectiveness of the proposed methods. [ABSTRACT FROM AUTHOR]

Solar cells devices based on inorganic/polymer heterojunction can be a possible solution to harvest solar energy and convert to electric energy with high efficiency through a cost-effective fabrication. The solution-process method can be easily used to produce large area devices. Moreover, due to the intrinsic different charge separation, diffusion or recombination in various semiconductors, the interfaces between each component may strongly influence the inorganic/polymer heterojunction performance. Here we prepared a n-type Ag 3 CuS 2 (Eg = 1.25 eV) nanostructured film through a room-temperature element reaction process, which was confirmed as direct bandgap semiconductor through density function theory simulation. This Ag 3 CuS 2 film was spin-coated with an organic semiconducting poly(3-hexythiophene) (P3HT) or polythieno[3,4-b]-thiophene-co-benzodithiophene (PTB7) film, which formed an inorganic/polymer heterojunction. After constructing it to a solar cell device, the power conversion efficiencies of 0.79% and 0.31% were achieved with simulated solar illumination on Ag 3 CuS 2 /P3HT and Ag 3 CuS 2 /PTB7, respectively. A possible mechanism was discussed and we showed the charge separation at interface of inorganic and polymer semiconductors played an important role. [ABSTRACT FROM AUTHOR]

A downward micro-nozzle system is investigated for the fluidization of fine particles. To study the impact of the gas flow from the nozzle on the fluidization, the gas distribution below the nozzle is measured in a bed filled with 76 μm Puralox particles. A high speed X-ray tomography system, consisting of 3 X-ray sources and 2 layers of 32 detectors for each source, is employed to visualize the gas distribution with a temporal resolution of 2500 fps. Both the time-averaged and time resolved results are analyzed by combining the tomographic images from different measurement heights. A bubbling area, diluted area, and compacted area are found from the time averaged results. From time-series analysis, a stable bubbling flow is detected from both the cross-correlation of the raw data and image reconstruction. The penetration depth is also estimated. The results are validated with correlations from literature. [ABSTRACT FROM AUTHOR]

Chemical looping combustion (CLC) as a potential CO 2 capture technology has been considered as a promising and likely alternative to traditional combustion technology to mitigate the CO 2 emission due to its prosecution of CO 2 sequestration at a low cost. Although a number of studies on the hydrodynamic behaviours of the CLC process in fuel reactor have been documented in the open literature, there have been rare studies on the correlation between the bubble formation and the local particulate volume fraction. This paper aims to investigate the CLC process in a fuel reactor using the CFD modelling, coupled with the heterogeneous reactions, the hydrodynamics and reaction kinetics occurring in the fuel reactor. A parameter correlating the occurrence of bubble and dynamic properties is proposed. The parameter may be acted as an indicator of time-dependent bubble evolution with a potential to be adopted in the CLC for controlling the bubbling phenomena since the occurrence of the bubbles at specific positions is highly correlated with the local large eddies embedded in the flow. The results obtained clearly indicate that the CFD model developed in the current study reasonably forecasts the hydrodynamic behaviours and important phenomena observed in the fuel reactor. [ABSTRACT FROM AUTHOR]