Investigation of the concurrent effects of ALP-photon and ALP-electron couplings in Collider and Beam Dump Searches

Axion-like particles (ALPs) have been studied in numerous experiments to search for their interactions, but most studies have focused on deriving bounds for the single coupling. However, in ultraviolet (UV) models, these couplings can appear simultaneously, and their interplay could have important implications for collider and beam dump searches. In this study, we investigate the concurrent effects of the ALP-photon and ALP-electron couplings in a simplified model and examine how their simultaneous presence modifies existing bounds. We find that modifications to production cross-sections, decaying branching ratios, and the lifetime of the ALP are the major effects. Our results show that low-energy electron-positron colliders such as Belle-II and BaBar are primarily affected by the first two factors, while beam dump experiments such as E137 and NA64 are affected by the cross sections and lifetime. We also consider two UV models - the KSVZ model and a lepton-specific version of the DFSZ model - which have only one of the two couplings at tree-level. However, the other coupling can be generated at loops, and our analysis reveals that the simultaneous presence of the two couplings can significantly modify existing bounds on these models for $10^{-3} < m_a < 10$ GeV, especially for beam dump experiments. Overall, our study highlights the importance of considering the concurrent effects of the ALP-photon and ALP-electron couplings in future collider and beam dump analyses.Comment: 29 pages, 11 figures; v2: matched to journal versio

Response of Freshwater Biofilm to pollution and ecosystem in Baiyangdian Lake of China

AbstractAn experimental study was undertaken to highlight the potential applicability of biofilms as biomonitors forming simultaneously on natural and artificial substrata in Baiyngdian Lake(China).We investigated the responses of freshwater biofilm in 8 site of Baiyngdian Lake and compared with control site (a reservoir) to assess the relative health of water. Exposure to pollution and its impact on biofilms were assessed by measuring the biomass production, Chlorophyll concentration, the algal composition, extracellular enzyme activity of bacterial communities and Polysaccharide content. This relation between the biological characters of biofilms and water quality were discussed, and the relative health of regions were demonstrated by the degree of deviation based on bioflim indicator in the following order: Fu river (S4) < Duan cun (S8) < Nan Liuzhuang (S5) < Wang jiazai (S1) < Cai putai (S7) < Zao lingzhuang (S2)< Shao Chedian (S3).. The result indicated that biofilm can provide information for pollution detection and ecological health assessment of water, and biofilm on aritificial substrata was recommended for biomonitoring in the Baiyangdian Lake

Study of imbibition in various geometries using phase field method

Phase field method has been widely utilized to study multiphase flow problems, but has seldom been applied to the study of imbibition. Previous methods used to simulate imbibition, such as moving mesh method, need to specify capillary pressure as a boundary condition a priori, whereas phase field method can calculate capillary pressure automatically for various geometries. Therefore, phase field method would be a versatile tool for the study of imbibition in various geometries. In this paper, phase field method is employed to solve dynamical imbibition problem in various geometries, including straight tube, conical tube and structures in which the topology changes. The variation of the imbibition height with respect to time from phase field simulation is verified with theoretical predictions from Lucas-Washburn law in a straight capillary tube with three gravitational scenarios. In addition, the capillary pressure and velocity field are found to be consistent with Laplace-Young equation and Hagen-Poiseuille equation in various geometries. The applicability and accuracy of the phase field method for the study of imbibition in structures with changing topology are also discussed.Cited as: Xiao, J., Luo, Y., Niu, M., Wang, Q., Wu, J., Liu, X., Xu, J. Study of imbibition in various geometries using phase field method. Capillarity, 2019, 2(4): 57-65, doi: 10.26804/capi.2019.04.0

Experimental and Computational Investigation of binary drop collisions under elevated pressure

[EN] Spray systems often operate under extreme ambient conditions like high pressure, which can have a significant influence on important spray phenomena. One of these phenomena is binary drop collisions. Such collisions, depending on the relative velocity and the impact parameter (eccentricity of the collision), can lead to drop bouncing, coalescence or breakup. This experimental and computational study is focused on the description of the phenomenon of drop bouncing, which is caused by a thin gas layer preventing the drops coalescence. To identify the main influencing parameters of this phenomenon, experiments on binary drop collisions are performed in a pressure chamber. This experimental system allows us to investigate the effect of an ambient pressure (namely the density and viscosity of the surrounding gas) on the bouncing/coalescence threshold.This research was supported by the the German Scientific Foundation (Deutsche Forschungsgemeinschaft) in the framework of the SFB TRR 75 Collaborative Research Center, subprojects C04 and A07. The author Louis Reitter has contributed to the present manuscript in the framework of the course "Sprays and Atomization".Reitter, L.; Liu, M.; Breitenbach, J.; Huang, K.; Bothe, D.; Brenn, G.; Pan, K.... (2017). Experimental and Computational Investigation of binary drop collisions under elevated pressure. En Ilass Europe. 28th european conference on Liquid Atomization and Spray Systems. Editorial Universitat Politècnica de València. 815-821. https://doi.org/10.4995/ILASS2017.2017.4758OCS81582

A Novel Strategy to Construct Yeast Saccharomyces cerevisiae Strains for Very High Gravity Fermentation

Very high gravity (VHG) fermentation is aimed to considerably increase both the fermentation rate and the ethanol concentration, thereby reducing capital costs and the risk of bacterial contamination. This process results in critical issues, such as adverse stress factors (ie., osmotic pressure and ethanol inhibition) and high concentrations of metabolic byproducts which are difficult to overcome by a single breeding method. In the present paper, a novel strategy that combines metabolic engineering and genome shuffling to circumvent these limitations and improve the bioethanol production performance of Saccharomyces cerevisiae strains under VHG conditions was developed. First, in strain Z5, which performed better than other widely used industrial strains, the gene GPD2 encoding glycerol 3-phosphate dehydrogenase was deleted, resulting in a mutant (Z5ΔGPD2) with a lower glycerol yield and poor ethanol productivity. Second, strain Z5ΔGPD2 was subjected to three rounds of genome shuffling to improve its VHG fermentation performance, and the best performing strain SZ3-1 was obtained. Results showed that strain SZ3-1 not only produced less glycerol, but also increased the ethanol yield by up to 8% compared with the parent strain Z5. Further analysis suggested that the improved ethanol yield in strain SZ3-1 was mainly contributed by the enhanced ethanol tolerance of the strain. The differences in ethanol tolerance between strains Z5 and SZ3-1 were closely associated with the cell membrane fatty acid compositions and intracellular trehalose concentrations. Finally, genome rearrangements in the optimized strain were confirmed by karyotype analysis. Hence, a combination of genome shuffling and metabolic engineering is an efficient approach for the rapid improvement of yeast strains for desirable industrial phenotypes

Numerical Study of Head-on Binary Droplet Collisions: Towards Predicting the Collision Outcomes

Binary droplet collision plays an important role in nature and in many technical processes involving sprays. The modeling of the collision outcomes, namely bouncing, coalescence, separation after temporary coalescence, and spatter (also called ‘shattering’ and ‘splashing’), establishes the basis for the investigation of the atomization processes on larger length scales. The aim of this thesis is to develop numerical methods that are employed in the prediction of the collision outcomes and the numerical investigation of the phenomena in binary droplet collisions which affect the collision outcomes. The in-house code Free Surface 3D (FS3D), which is based on the Volume of Fluid (VOF) method, is employed for the numerical simulations. The numerical investigations are restricted to head-on collisions. Spatter occurs at high energetic collisions, resulting in a thin liquid lamella that ruptures artificially in standard numerical simulations. In order to simulate spatter, an improved lamella stabilization algorithm has been developed and extensively validated. By means of properly chosen white noise disturbances of the initial velocity field, the instability of the rim of the collision complex is triggered and the spatter is successfully reproduced in the simulations. Very good agreements between the simulation results and the experiments are achieved. Based on the simulation results, the development of the rim instability is considered as an amplification of disturbances via a signal amplification system that is subdivided into three sequential connected subsystems. It is confirmed that the development of the rim instability in the linear phase of the instability can be predicted by the Rayleigh-Plateau instability theory. The influence of the droplet viscosity is studied numerically and it is shown that the collision outcome tends to be spatter when the droplet viscosity is reduced. This dependency decreases with the decrease of the droplet viscosity. The droplet viscosity influences the development of the rim instability mainly through varying the geometrical evolution of the rim. A successful elucidation of the mechanism of rim instability builds the foundation for the prediction of the occurrence of spatter and the prediction of the size distribution of the secondary droplets arising in spatter. The investigation of the mechanism of the rim instability in the context of binary droplet collisions is of general importance because the ejection of secondary droplets from an unstable rim also emerges in collisions of a droplet on a solid substrate or on a liquid film. Binary droplet collisions result in bouncing or coalescence at relatively small Weber numbers. The simulations of bouncing and coalescence have been successfully conducted by switching the boundary conditions on the collision plane. The simulation results are in good agreement with corresponding experiments. However, the simulations are not predictive because the collision outcome must be specified in advance. The difficulty of the prediction of bouncing versus coalescence lies in the fact that the thin gas film between the colliding droplets cannot be resolved in feasible simulations and that a physically meaningful coalescence criterion is missing in the numerical method. In order to facilitate the predictive simulation, a multi-scale simulation concept has been developed. In addition to the main solver FS3D, which solves the flow on the macroscopic scale, the multi-scale simulation concept consists of three parts: (1) A sub-grid-scale (SGS) model is integrated within the main solver FS3D. (2) Coalescence is numerically suppressed before a suitable coalescence criterion is contingently satisfied. (3) A numerical coalescence criterion is applied. Based on the lubrication theory, the SGS model is derived which accounts for the rarefied flow effect. The SGS model is implemented in FS3D and extensively validated. For the integration of the SGS model, the pressure in the gas film, which is solved by the SGS model, applies as a pressure boundary condition on the collision plane. Employing the first intersection of PLIC-surfaces with the collision plane as coalescence criterion, the collision outcome in the simulation can be both bouncing and coalescence. The predicted collision outcome, however, depends on the grid resolution. Employing zero gas film thickness (in algorithm tolerance) as coalescence criterion, the simulations result only in bouncing. It is shown that various possible corrections of the velocity field, which decides the transport of the liquid phase, have not led to a meaningful prediction of the transition between coalescence and bouncing. Further developments, e.g. the volume-averaged Volume of Fluid (VA-VOF) method, which takes into account the velocity difference within a computational cell, shall be implemented in future work to increase the accuracy of the transport of the fluid phase. By means of the multi-scale simulation it is qualitatively shown that the collision outcome tends to be coalescence at higher rarefaction in the gas phase

Numerical Study of Head-on Binary Droplet Collisions: Towards Predicting the Collision Outcomes

Binary droplet collision plays an important role in nature and in many technical processes involving sprays. The modeling of the collision outcomes, namely bouncing, coalescence, separation after temporary coalescence, and spatter (also called ‘shattering’ and ‘splashing’), establishes the basis for the investigation of the atomization processes on larger length scales. The aim of this thesis is to develop numerical methods that are employed in the prediction of the collision outcomes and the numerical investigation of the phenomena in binary droplet collisions which affect the collision outcomes. The in-house code Free Surface 3D (FS3D), which is based on the Volume of Fluid (VOF) method, is employed for the numerical simulations. The numerical investigations are restricted to head-on collisions. Spatter occurs at high energetic collisions, resulting in a thin liquid lamella that ruptures artificially in standard numerical simulations. In order to simulate spatter, an improved lamella stabilization algorithm has been developed and extensively validated. By means of properly chosen white noise disturbances of the initial velocity field, the instability of the rim of the collision complex is triggered and the spatter is successfully reproduced in the simulations. Very good agreements between the simulation results and the experiments are achieved. Based on the simulation results, the development of the rim instability is considered as an amplification of disturbances via a signal amplification system that is subdivided into three sequential connected subsystems. It is confirmed that the development of the rim instability in the linear phase of the instability can be predicted by the Rayleigh-Plateau instability theory. The influence of the droplet viscosity is studied numerically and it is shown that the collision outcome tends to be spatter when the droplet viscosity is reduced. This dependency decreases with the decrease of the droplet viscosity. The droplet viscosity influences the development of the rim instability mainly through varying the geometrical evolution of the rim. A successful elucidation of the mechanism of rim instability builds the foundation for the prediction of the occurrence of spatter and the prediction of the size distribution of the secondary droplets arising in spatter. The investigation of the mechanism of the rim instability in the context of binary droplet collisions is of general importance because the ejection of secondary droplets from an unstable rim also emerges in collisions of a droplet on a solid substrate or on a liquid film. Binary droplet collisions result in bouncing or coalescence at relatively small Weber numbers. The simulations of bouncing and coalescence have been successfully conducted by switching the boundary conditions on the collision plane. The simulation results are in good agreement with corresponding experiments. However, the simulations are not predictive because the collision outcome must be specified in advance. The difficulty of the prediction of bouncing versus coalescence lies in the fact that the thin gas film between the colliding droplets cannot be resolved in feasible simulations and that a physically meaningful coalescence criterion is missing in the numerical method. In order to facilitate the predictive simulation, a multi-scale simulation concept has been developed. In addition to the main solver FS3D, which solves the flow on the macroscopic scale, the multi-scale simulation concept consists of three parts: (1) A sub-grid-scale (SGS) model is integrated within the main solver FS3D. (2) Coalescence is numerically suppressed before a suitable coalescence criterion is contingently satisfied. (3) A numerical coalescence criterion is applied. Based on the lubrication theory, the SGS model is derived which accounts for the rarefied flow effect. The SGS model is implemented in FS3D and extensively validated. For the integration of the SGS model, the pressure in the gas film, which is solved by the SGS model, applies as a pressure boundary condition on the collision plane. Employing the first intersection of PLIC-surfaces with the collision plane as coalescence criterion, the collision outcome in the simulation can be both bouncing and coalescence. The predicted collision outcome, however, depends on the grid resolution. Employing zero gas film thickness (in algorithm tolerance) as coalescence criterion, the simulations result only in bouncing. It is shown that various possible corrections of the velocity field, which decides the transport of the liquid phase, have not led to a meaningful prediction of the transition between coalescence and bouncing. Further developments, e.g. the volume-averaged Volume of Fluid (VA-VOF) method, which takes into account the velocity difference within a computational cell, shall be implemented in future work to increase the accuracy of the transport of the fluid phase. By means of the multi-scale simulation it is qualitatively shown that the collision outcome tends to be coalescence at higher rarefaction in the gas phase

GAIN: A Gated Adaptive Feature Interaction Network for Click-Through Rate Prediction

CTR (Click-Through Rate) prediction has attracted more and more attention from academia and industry for its significant contribution to revenue. In the last decade, learning feature interactions have become a mainstream research direction, and dozens of feature interaction-based models have been proposed for the CTR prediction task. The most common approach for existing models is to enumerate all possible feature interactions or to learn higher-order feature interactions by designing complex models. However, a simple enumeration will introduce meaningless and harmful interactions, and a complex model structure will bring a higher complexity. In this work, we propose a lightweight, yet effective model called the Gated Adaptive feature Interaction Network (GAIN). We devise a novel cross module to drop meaningless feature interactions and preserve informative ones. Our cross module consists of multiple gated units, each of which can independently learn an arbitrary-order feature interaction. We combine the cross module with a deep module into GAIN and conduct comparative experiments with state-of-the-art models on two public datasets to verify its validity. Our experimental results show that GAIN can achieve a comparable or even better performance compared to its competitors. Furthermore, in order to verify the effectiveness of the feature interactions learned by GAIN, we transfer learned interactions to other models, such as Logistic Regression (LR) and Factorization Machines (FM), and find out that their performance can be significantly improved

Lensless Computational Imaging Technology Using Deep Convolutional Network

Within the framework of Internet of Things or when constrained in limited space, lensless imaging technology provides effective imaging solutions with low cost and reduced size prototypes. In this paper, we proposed a method combining deep learning with lensless coded mask imaging technology. After replacing lenses with the coded mask and using the inverse matrix optimization method to reconstruct the original scene images, we applied FCN-8s, U-Net, and our modified version of U-Net, which is called Dense-U-Net, for post-processing of reconstructed images. The proposed approach showed supreme performance compared to the classical method, where a deep convolutional network leads to critical improvements of the quality of reconstruction

Fabrication and Adsorption Optimization of Novel Magnetic Core-shell Chitosan/Graphene Oxide/β-cyclodextrin Composite Materials for Bisphenols in Aqueous Solutions

A novel magnetic composite material, Fe3O4@SiO2/chitosan/graphene oxide/&beta;-cyclodextrin (MCGC), was prepared by multi-step methods. Various methods were used to systematically characterize the morphology, composition, structure, and magnetic properties of MCGC. The results obtained show that the composite material has good morphology and crystal structure and can be separated quickly by an external magnetic field. The operation is relatively easy, and the raw materials used to prepare this material are economical, easy to obtain, and environmentally friendly. The performance and adsorption mechanism for using this material as an adsorbent to remove bisphenol A (BPA) and bisphenol F (BPF) from water were studied. The adsorption parameters were optimized. Under optimal conditions, MCGC was found to remove more than 90% of BPA and BPF in a mixed solution (20 mg/L, 50 mL); the adsorption process for BPA and BPF on MCGC was found to follow a Redlich&ndash;Peterson isotherm model and Pseudo-second-order kinetic model. The adsorption mechanism for MCGC may involve a combination of various forces. Recycling experiments showed that after five uses, MCGC retained a more than 80% removal effect for BPA and BPF, and through real sample verification, MCGC can be used for wastewater treatment. Therefore, MCGC is economical, environmentally friendly, and easy to separate and collect, and has suitable stability and broad application prospects