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High-speed solenoid valve (HSV) is the key component of electronic control fuel injection system for diesel engine. Improving the dynamic response speed of HSV will be able to achieve higher injection precision and more flexible fuel injection law, thus reducing gas emissions of diesel engine and improving its fuel economy. However, HSV is the complex coupling system of electric field, magnetic field, mechanical movement and flow field, and the interactions of multiple parameters exist between the fields for HSV. To improve the dynamic response speed of HSV is a complex optimization problem of multiple physical field and multiple parameters. A zero-dimensional approximation coupling model of HSV can be developed instead of the CAE (computer aided engineering) models or physical experiments, which conduces to achieve the efficient prediction and global optimization of performances. So the approximation model method was employed in this paper. First, the structure and principle of HSV for electronic unit pump of diesel engine were presented. Second, the three-dimensional (3D) finite element model of HSV was developed to calculate the electromagnetic force, and its accuracy was verified by means of the comparison with experimental data. Third, 3 major methods of experimental design, i.e. central composite faced-centered design (CCF), central composite inscribed design (CCI) and optimal latin hypercube design (OLH), and 3 typical approximation methods, i.e. quadratic polynomial response surface model (RSM), Kriging model (KR) and radial basis function model (RBF) were introduced. Fourth, 6 key parameters including 2 field coupling parameters, i.e. working air gap and drive current, and 4 structure parameters, i.e. coil turns, side pole radius, thickness and radius of armature were determined for establishing the approximate models. Next, 6 groups of sample points were designed, whose response values of electromagnetic forces were obtained by the 3D finite element model of HSV. Four of the groups were designed with different sizes by the OLH, and the other 2 groups were designed by the CCF and CCI. Then, 18 groups of electromagnetic force approximation models were developed by combining the 6 groups of experimental design with the 3 typical approximation methods introduced. To compare the accuracy of approximation models, 3 kinds of evaluation indices were introduced. They were multiple correlation coefficient, average absolute error and root mean square error respectively. In the end, the effects of different sample point sizes, experimental design methods and approximate methods on the accuracy of electromagnetic force approximation models were analyzed in detail. It is concluded that the accuracy of approximate model doesn't increase monotonically with the increase of the set size of sample points, and too many sample points maybe leads to the decrease of the accuracy of approximate model; the OLH has good adaptability with the KR and RBF, and can be given priority for developing approximation models. In addition, the best solution for establishing electromagnetic force approximation model of HSV is the combination of the KR and OLH, whose size of sample points is 1.5 times of the minimum sample points required by the quadratic polynomial response surface model. Its multiple correlation coefficient, average absolute error and root mean square error are 0.97, 0.06 and 0.09 respectively. It provides a theoretical guidance for the establishment of the zero-dimensional approximation coupling model and the optimization of HSV. [ABSTRACT FROM AUTHOR]

Electronic unit pump (EUP) is a timing controlled fuel injection system used in diesel engines to meet the increasingly strict exhaust emission regulation and improve the economy of the fuel injection. As the key actuator of EUP, high-speed solenoid valve (HSV) determines the fuel injection timing and quantity in EUP. The electromagnetic force of HSV has a significant influence on the response speed and the stability of EUP, which depends greatly on the structure parameters of HSV. However, it is still not comprehensive in the parameter analysis of HSV for most experiments and simulations on the influence rules of single parameter on electromagnetic force or the parameters' influence rules for only one operating condition of HSV. In order to improve effectiveness of HSV's parameters' design and matching, six parameters' influence rules and the parameters' interaction principles on electromagnetic force under overall operating conditions were revealed by correlation analysis. Coils, armature and iron core were the most important parts for generating the electromagnetic force of HSV, and the 3D numerical simulation model of HSV was established in Ansoft Maxwell according to the three parts' actual structures, moreover the accuracy of the model was verified at different working air gaps and driving currents by experiment. Pole length, coil turns, coil location, armature thickness, damping hole location and damping hole radius were selected as the six key parameters of HSV and every parameter's three levels were determined based on their actual values. Due to HSV's working characteristics, the overall operating condition of HSV was dispersed into nine operating condition points to approximate HSV's entire working process. Based on the three levels of each of the six parameters, 47 sample points of the parameters combinations were obtained effectively and accurately by the method of design of experiments (DOE), in which the electromagnetic force was determined as a response variable and the six parameters were selected as experimental factors. Then the electromagnetic force of 423 sample points were got by using the 3D numerical simulation model of HSV to do experiment with the same times. At last, the correlation coefficients of first and second order factors formed by the six key parameters with electromagnetic force were explored under overall operating conditions according to the thought of correlation analysis. By making correlation analysis, the influence rules of the first order factors on electromagnetic force were revealed under overall operating conditions. The rules showed that one factor with significant correlation to electromagnetic force was coil turns, and the correlation decreased with the increase of driving current and increased with the increase of working air gap under different working conditions; the other factor with significant correlation to electromagnetic force was armature thickness, and the correlation increased with the increase of driving current and decreased with the increase of working air gap under different working conditions. The correlations of second order factors to electromagnetic force tended to be very complicate under overall operating conditions. In addition, the interaction principles of coil turns with armature thickness, armature thickness with damping hole location and damping hole location with damping hole radius were revealed. The electromagnetic force of HSV is determined by the complex interactions of characteristic parameters. [ABSTRACT FROM AUTHOR]

During a fuel injection cycle pressure inside Combination Electronic Unit Pump (CEUP) fuel injection system varies from low (∼50 bars) to very high (∼1500 bars) in fractions of seconds depending on the operating conditions. Physical properties of fuel including density, acoustic wave speed and bulk modulus also vary as a function of rapidly varying fuel pressure. A detailed analysis of these key fuel properties with our improved frequency dependent model with viscous damping developed in MATLAB is presented for both diesel and biodiesel fuel Rapeseed Methyl Ester (RME). Quantitative analysis of developed model confirms that model predictions are quite realistic and accurate across range of operating conditions of diesel engine. [ABSTRACT FROM AUTHOR]

High pressure common rail (HPCR) fuel injection system is the main development trend for fuel injection system of diesel engine. Precise controlling of injection pressure and multiple injections are the advantages and key features of the HPCR system. Affect of pilot injection quantity (PIQ) and pilot-main interval (PMI) on main injection quantity fluctuation (MIQF) has been investigated in this paper by evaluating performance coherence and stability of injection quantity of diesel engine. A numerical model of HPCR system has been development in AMESim environment. Predicting accuracy of the numerical model has been validated by comparing its results with experimental data. The results show that the pilot injection triggers pressure cyclical fluctuation in the electro-injection delivery chamber and gives rise to MIQF. Amplitude of MIQF decreases with increase of PMI and increase with increase of PIQ. Moreover, variation of PIQ has also influence on both the amplitude and the phase of MIQF. Influence of MIQ on amplitude of MIQF depends on how many pressure fluctuation cycles have been incorporated in the main injection. [ABSTRACT FROM AUTHOR]

Thermal runaway and its propagation within lithium-ion battery systems pose significant challenges to widespread adoption in electric vehicles and energy storage systems. Deploying a thermal barrier between adjacent batteries is a common and effective strategy to prevent thermal propagation. This experimental study evaluates the inhibitory effect of nanofiber aerogel on thermal propagation within high-energy-density lithium-ion battery modules. The results indicate that increasing the thickness of nanofiber aerogel prolongs the average time interval between thermal runaway propagation events between adjacent batteries and increases their peak temperature difference, while the maximum surface temperature of each battery exhibits an overall downward trend. Specifically, compared to no nanofiber aerogel, a 0.5 mm nanofiber aerogel extends the average propagation time by 2 times, and a 1.0 mm nanofiber aerogel successfully prevents thermal propagation from the third to the fourth battery, with an average time extension of nearly 6 times. Furthermore, it is found that thermal runaway propagation can be effectively prevented when the aerogel thickness exceeds 2.0 mm. The microstructure of both fresh and damaged nanofiber aerogels was examined using Scanning Electron Microscopy to validate and analyze their robust durability. This study provides valuable insights for designing safer high-energy-density battery systems. • Different thicknesses of nanofiber aerogels are utilized to prevent thermal runaway propagation in battery module. • Thermal runaway propagation of high specific energy lithium-ion battery modules exhibits a slowdown trend. • 1.0 mm of nanofiber aerogel successfully prevented the thermal runaway propagation of 3rd to 4th cell. [ABSTRACT FROM AUTHOR]

The injection rate and injection volume are essential parameters for the combustion process, which greatly affect the engine efficiency and emission performance. However, at the current time the injection information cannot be obtained in real time during the actual operation of engine. This paper presents a novel real-time estimation method for the injection rate and injection volume based on the measurable rail pressure. A comprehensive dynamic model is derived by considering both the effect of fuel injection and supply process on the pressure fluctuation. Then a linear time-varying state space model is constructed by choosing three appropriate state variables. On this basis, considering the measurement noise and model uncertainty, a Kalman filter-based estimation method of the injection information is investigated. And the noise covariance matrix Q is optimally designed to adapt to a wide range of operating conditions. The proposed estimation method is validated on the different conditions, and the results show the injection rate estimation errors are within 4.5 %, the injection volume estimation errors are within 4 %. And on the situation with overlap of injection and supply process, the injection rate and injection volume estimation errors are all within 4.5 %. • A novel real-time estimation method for the fuel injection rate and injection volume is proposed. • To decouple the effects of fuel injection and supply on the pressure fluctuation, a comprehensive dynamic model is derived. • A linear time-varying state space model with three state variables pdown, p ˙ down , pup is proposed and built. • A Kalman filter-based estimation for the injection information in real-time is investigated. • The accuracy estimation results are achieved at the overlap of fuel injection and supply condition. [ABSTRACT FROM AUTHOR]

To examine the prevalence of comorbidities in Chinese urticaria patients and assess medication use patterns across different ages (6-11 years, 12-17 years, above 18 years), a retrospective cohort study was performed in 192,647 urticaria patients within the Health Database. After 1:1 propensity score matching, 166,921 people were divided into the urticaria group and the control group, and the follow-up data were collected within 2 years. During the 12-month and 24-month follow-up period, significant comorbidities identified included allergic rhinitis and asthma, with distinct patterns observed across age groups. Chronic urticaria patients often have complications, such as allergic rhinitis, upper respiratory infection, oropharyngeal infection, and dental caries. The study underscores the need for age-specific treatment strategies in urticaria management.

Analysis consisting of numerical simulations along with lab experiments of interaction effects between key parameters on the electromagnetic force based on response surface methodology (RSM) has been also proposed to optimize the design of high-speed solenoid valve (HSV) and improve its performance. Numerical simulation model of HSV has been developed in Ansoft Maxwell environment and its accuracy has been validated through lab experiments. Effect of change of core structure, coil structure, armature structure, working air gap, and drive current on the electromagnetic force of HSV has been analyzed through simulation model and influence rules of various parameters on the electromagnetic force have been established. The response surface model of the electromagnetic force has been utilized to analyze the interaction effect between major parameters. It has been concluded that six interaction factors including working air gap with armature radius, drive current with armature thickness, coil turns with side pole radius, armature thickness with its radius, armature thickness with side pole radius, and armature radius with side pole radius have significant influence on the electromagnetic force. Optimal match values between coil turns and side pole radius; armature thickness and side pole radius; and armature radius and side pole radius have also been determined.