The phenomenon of burning cone drop is a serious quality defect in super slim cigarettes. In order to monitor the burning cone drop, a segmentation model conveniently and effectively about cigarette packing density was established and used for predicting the burning cone drop rate. The method is a non-destructive testing (NDT), which is applied by using cigarette density and its change rate.
The model of cigarette density segmentation method is based on a straight line ρ=A×ρ’+B in the Cartesian coordinate system with abscissa ρ′ and ordinate ρ. The straight line split the coordinate system into two regions. By measuring the density of the super slim cigarettes, the position of the point (ρ’, ρ) can be determined, then the burning cone drop tendency can be predicted.
When verifying the accuracy of the model, it is found that the predicted value and the measured value are basically near the 1:1 line, the coefficient of determination (R2) and the index of agreement (D index) between predicted and observed values are 0.98 and 0.99 respectively, and the normalized root mean square error (nRMSE) is 11.8%. The coefficient of variation of the predicted burning cone drop rate is 6.5% for 10 consecutive replicates.
The cigarette density segmentation method model is suitable for predicting burning cone drop of the super slim cigarette samples with varying packing densities or cut tobacco distribution. The model has a good effect on the burning cone drop prediction under certain conditions, and it has an important guiding significance for super slim cigarette production and quality inspection.
To study the precision of the fire water monitor with important influence on fire extinguishing effect, the drop point of fire water monitor is studied. The quadratic drag model is selected on the basis of the analysis of the mechanical model of the fluidic microbody, considering the change of the cross-sectional area caused by velocity and breakup of the water jet. The boundary between breakup and atomization is clarified, and the change of diameter and area of the droplet is also discussed based on the theory of liquid jet breakup, to build a dynamic breakup model of air resistance and broken jet. The jet trajectory of the fire water monitor is mainly influenced by the initial velocity, pitching angle, air resistance, and other factors. In this paper, the influence of different parameters on the jet drop point is considered. The analysis and comparison of all the points are performed, and the range of uncertainty is obtained. Finally, the accurate prediction of the jet trajectory is analyzed.
The primary objective of this study was to establish a model for predicting the jet trajectory of a firewater monitor. The jet trajectory is mainly affected by its own gravity and air resistance, and the magnitude of the air resistance changes with the cross-sectional area of the jet. The model is established by combining air resistance changes and breakup theory, and the factors affecting the location of jet trajectory are studied. The accuracy and reliability of the model is verified by comparative analysis of theoretical simulation data and experimental data. The error between the prediction and experimental data that can be maintained is about 10 % on average, which can meet the engineering application requirements. In addition, the shape of the jet and analyses of the causes of shape asymmetry are discussed.
In order to find the possibility of setting vibration mitigation measures at the transmission path for in-tunnel excitation source, a numerical calculation model of the tunnel and foundation was constructed. Using measurement vibration as the in-put excitation load, ground vibration propagation characters were calculated in cases of setting two common used vibration isolation measures, including open trench and buried concrete wall barrier. Calculation results indicated the open trench and buried concrete wall barrier can ideally shield the propagation of vibration induced by in-tunnel excitation source.
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