Parameter sensitivity analysis for diesel spray penetration prediction based on GA-BP neural network

Machine learning has started to be used in engine research to optimize combustion and predict fuel spray characteristics. This paper presents the development of a machine learning model using a Genetic Algorithm-Backpropagation (GA-BP) neural network to predict spray penetration. The GA-BP neural network was selected for its ability to optimize neural network weights and thresholds, thereby improving model convergence and avoiding local minima, which are common challenges in complex, non-linear problems such as spray prediction. The model was trained using experimental data from diesel injector spray tests, and its accuracy was evaluated through parametric sensitivity analysis, examining the influence of various input factors. A comparison between the machine learning model and the traditional empirical formulas of spray penetration revealed that the machine learning model achieved greater accuracy. In terms of the sensitivity to inputs, it is interesting to find that the cognition of machines is different from that of humans. When an input parameter does not have any functional relationship with other input parameters, the absence of this input parameter will lead to a significant decrease in the accuracy of the output result. The results demonstrate that the machine learning approach offers higher accuracy and better generalizability compared to traditional empirical methods. This study recommends the ways to get better results of penetration prediction with BP neural networks, which is efficient in training and utilizing Artificial Neural Networks (ANNs).<br/

Evolutionary Enhancement of Zika Virus Infectivity in Aedes aegypti Mosquitoes

Zika virus (ZIKV) remained obscure until the recent explosive outbreaks in French Polynesia (2013-2014) and South America (2015-2016). Phylogenetic studies have shown that ZIKV has evolved into African and Asian lineages. The Asian lineage of ZIKV was responsible for the recent epidemics in the Americas. However, the underlying mechanisms through which ZIKV rapidly and explosively spread from Asia to the Americas are unclear. Non-structural protein 1 (NS1) facilitates flavivirus acquisition by mosquitoes from an infected mammalian host and subsequently enhances viral prevalence in mosquitoes. Here we show that NS1 antigenaemia determines ZIKV infectivity in its mosquito vector Aedes aegypti, which acquires ZIKV via a blood meal. Clinical isolates from the most recent outbreak in the Americas were much more infectious in mosquitoes than the FSS13025 strain, which was isolated in Cambodia in 2010. Further analyses showed that these epidemic strains have higher NS1 antigenaemia than the FSS13025 strain because of an alanine-to-valine amino acid substitution at residue 188 in NS1. ZIKV infectivity was enhanced by this amino acid substitution in the ZIKV FSS13025 strain in mosquitoes that acquired ZIKV from a viraemic C57BL/6 mouse deficient in type I and II interferon (IFN) receptors (AG6 mouse). Our results reveal that ZIKV evolved to acquire a spontaneous mutation in its NS1 protein, resulting in increased NS1 antigenaemia. Enhancement of NS1 antigenaemia in infected hosts promotes ZIKV infectivity and prevalence in mosquitoes, which could have facilitated transmission during recent ZIKV epidemics

3D multi-nozzle system with dual drives highly potential for 3D complex scaffolds with multi-biomaterials

Recently, additive manufacturing is one of the most focused research topics due to its explosive development, especially in manufacturing engineering and medical science. In order to build 3D complex scaffolds with multi-biomaterials for clinical application, a new 3D multi-nozzle system with dual-mode drives, i.e. ejection and extrusion was developed. In this paper, much effort was made to gain fine control of droplet and excellent coordination during fabrication. Specifically, the parameters that influence the size and stability of droplet most was intensively studied. Considering that the biomaterials used in the future may have much difference in properties, the combination of parameters was investigated to facilitate the settings for certainsized droplets, which are potentially eligible for bio-printing. The dispensing nozzles can work well both in independent and convergent mode, which can be freely switched. Outstanding to the most currently used 3D bio-printing techniques, this system can fabricate scaffolds with multi-materials of both low viscosity (by pneumatic dispensing) and high viscosity (through motor extrusion). It is highly expected that this system can satisfy clinical application in the near future

Effect of Baicalein on GLUT4 Translocation in Adipocytes of Diet-Induced Obese Mice

Background/Aims: Although baicalein has been shown to increase insulin sensitivity in liver of mice, there is no literature available about the effect of baicalein on glucose transporter 4 (GLUT4) translocation from intracellular membrane pools to plasma membranes in adipocytes of diet-induced obese mice. Methods: In the present study, the obese model was induced in mice fed a high fat diet (20% carbohydrates, 21% protein and 59% fat) for 16 weeks. The diet-induced obese mice were given 20mg/kg baicalein intraperitoneally (i.p.) once a day for 21 days. The plasma insulin was measured by enzyme-linked immunosorbent assay. Fasting blood glucose and insulin resistance indexes were measured by glucose tolerance test (GTT). The expression levels of PGC-1α, UCP1, GLUT4, PPARγ, pP38MAPK, pERK and pAKT in adipocytes were determined by quantitative real-time polymerase chain reaction and western blotting. Results: The present findings showed that administration of baicalein decreased pP38MAPK, pERK and PPARγ levels, but enhanced pAKT, PGC-1α and UCP1 contents as well as GLUT4 expression in adipocytes, and reversed high fat diet-induced glucose intolerance, hyperglycemia and insulin resistance in diet-induced obese mice. Moreover, baicalein treatment increased GLUT4 concentration in plasma membranes of adipocytes, i.e. baicalein may prevent insulin resistance through the GLUT4 translocation from intracellular membrane compartments to plasma membranes in adipocytes. Conclusion: These results suggest that baicalein is a powerful and promising agent for treatment of obesity and insulin resistance via Akt/GLUT4 pathway

Sophoraflavenone G Restricts Dengue and Zika Virus Infection Via RNA Polymerase Interference

Flaviviruses including Zika, Dengue and Hepatitis C virus cause debilitating diseases in humans, and the former are emerging as global health concerns with no antiviral treatments. We investigated Sophora Flavecens, used in Chinese medicine, as a source for antiviral compounds. We isolated Sophoraflavenone G and found that it inhibited Hepatitis C replication, but not Sendai or Vesicular Stomatitis Virus. Pre- and post-infection treatments demonstrated anti-flaviviral activity against Dengue and Zika virus, via viral RNA polymerase inhibition. These data suggest that Sophoraflavenone G represents a promising candidate regarding anti-Flaviviridae research

RIM Experiment on Fuel Adhesion Characteristics of Inclined-Wall-Impinging Spray under Cross-Flow Conditions

The impingement of fuel sprays on the piston surface significantly affects mixture formation, combustion performance, and pollutant emissions in Direct-Injection Spark-Ignition (DISI) engines. To better understand the fuel adhesion behavior, the fuel adhesion characteristics of fuel spray impinging on the flat wall under cross-flow condition were investigated in this work. Refractive Index Matching (RIM) were employed to observe the propagation of fuel adhesion. Then the area, mass, and thickness of fuel adhesion were evaluated under various cross-flow velocities. Also, the propagation mechanism and lifetime prediction of fuel adhesion under the cross-flow conditions were revealed. The experimental results can provide necessary guidance on the operating conditions of airflow inside the engine

The effect of split injection on fuel adhesion characteristics under static flow and cross-flow field conditions

The flat-wall wetting phenomenon is inevitable because of the smaller cylinder volume and higher injection pressure inside direct-injection spark ignition (DISI) engines. The fuel adhesion phenomenon after wall impingement negatively affects the fuel spray mixture formation, the fuel consumption, and the pollutant emissions. In this study, the effects of different fuel injection strategies on the wall-impingement behavior were compared under static flow and cross-flow field conditions. The refractive index matching (RIM) method and high-speed video (HSV) camera were adopted to measure the propagation of fuel adhesion and the spray structure of the vertical plane, respectively. Meanwhile, a dimensionless parameter named “deformation coefficient Id,” which is defined as the fuel adhesion length divided by the width, is proposed to evaluate the degree of distortion of the fuel adhesion. Therefore, when Id approaches 1, the fuel adhesion shape approaches a circle. The results show that the cross-flow promotes the diffusion of the fuel spray, which leads to an increase in the fuel adhesion area. The fuel adhesion shape is similar to that of a slender strip under cross-flow field conditions, but almost maintains a circle under static flow field conditions. The cross-flow decreased the average fuel adhesion thickness. Meanwhile, the cross-flow also promotes the evaporation of the adhered fuel on a flat-wall, which leads to a reduction in the fuel adhesion area and mass with time. Additionally, it was found that triple injection can decrease the fuel adhesion thickness, area, and mass ratio under cross-flow field conditions. To achieve carbon neutrality, optimizing fuel injection strategies to reduce emissions is one of the primary purposes of this study.<br/

RIM Experiment on Fuel Adhesion Characteristics of Inclined-Wall-Impinging Spray under Cross-Flow Conditions

The impingement of fuel sprays on the piston surface significantly affects mixture formation, combustion performance, and pollutant emissions in Direct-Injection Spark-Ignition (DISI) engines. To better understand the fuel adhesion behavior, the fuel adhesion characteristics of fuel spray impinging on the flat wall under cross-flow condition were investigated in this work. Refractive Index Matching (RIM) were employed to observe the propagation of fuel adhesion. Then the area, mass, and thickness of fuel adhesion were evaluated under various cross-flow velocities. Also, the propagation mechanism and lifetime prediction of fuel adhesion under the cross-flow conditions were revealed. The experimental results can provide necessary guidance on the operating conditions of airflow inside the engine

Effect of wall-impingement distance on fuel adhesion characteristics of split injection spray under cross-flow condition

In direct-injection spark ignition (DISI) engines, high-pressure fuel injectors introduce fuel into the cylinder, causing the spray to come into contact with and adhere to the cylinder wall; this is known as fuel adhesion. Over time, fuel adhesion contributes to carbon deposition on the cylinder wall, which affects its thermal conductivity and consequently diminishes engine combustion efficiency. This study investigates the influence of different impingement distances and cross-flow velocities on fuel adhesion under the triple injection strategy. The fuel adhesion propagation and side-view spray are measured using refractive index matching (RIM) and Mie scattering, respectively. The findings demonstrate that high cross-flow velocity promotes the fuel adhesion shape to be elongated strips. In the early stage, the growth rate of the fuel adhesion area increases with an increase in cross-flow velocity. In the later stage, the decrease rate in the fuel adhesion area initially increases with an increase in the cross-flow velocity; however, when the critical velocity threshold (20 m/s) is exceeded, the decrease rate in the fuel adhesion area tends to stabilize. The average fuel adhesion thickness then accordingly decreases with the increase in the cross-flow velocity and impingement distance in the later stage. In addition, the cross-flow promotes the volatilization of spray and fuel adhesion, thereby decreasing the fuel adhesion mass over time. In the context of carbon neutrality, this study underscores the importance of optimizing fuel injection conditions to reduce emissions and fuel consumption