Average Of Relative Error Research Articles

Effect of Structural Parameters on the Jet Formation and Penetration Capability of Small Caliber Shaped Charges

Take small caliber high explosive antitank cartridge as research platform, establish 35mm diameter warhead model. Numerical simulation for the process of shaped charge jet forming and penetrating the target has been done through explosion mechanics analysis software AUTODYN. Effect of liner thickness, cone angle and charging length-diameter ratio on shaped charge jet performance has been analyzed. And the optimal combination of the structural parameters of the shaped charge has been determined by orthogonal optimum design. Results show that optimized shaped charge structure can penetrate 105mm steel target under simulation conditions and the maximum penetration depth of main charge in the explosion test is 100mm, the average value of penetration depth is 86.67mm. The minimum and average of relative error between results of static explosion test and numerical simulation are 4.76% and 17.46% respectively. The research results can provide theoretical and technical support for the optimization design and engineering application of small caliber shaped charge.

FBG-Based Deformation Reconstruction Method of Multipoint Elastic Support Thin Plate

For the multipoint elastic support thin plate deformation reconstruction problem, combined with the relationship between strain and deformation. A recursive numerical solution method of curvature incorporating displacement information is proposed. Estimation of boundary strains by elastic boundary conditions and interpolation algorithms. The detailed measurement principle of curvature and the curvature deformation mathematical model is derived and solved by the Runge–Kutta numerical solution method. The effect of cumulative errors can be greatly reduced. Finite element method (FEM)-based simulations for thin plate, the fiber Bragg grating (FBG) sensors placement strategy is determined, and have been conducted to preliminary validate the effectiveness of the proposed approach. To further verify the validity and repeatability of the proposed approach, the deflection obtained by the reconstruction algorithm and the actual deflection measured by laser displacement sensors were compared. Experimental results indicate that after the average strain coefficient correction strain, the proposed approach can accurately reconstruct the deformation of the thin plate, the average of relative error with a value of less than 9% under different loadings.

Parameterization of a Rising Smoke Plume for a Large Moving Ship Based on CFD

The plume rising height of a ship will directly affect the maximum ground concentration and distance from the source caused by flue gas emission. Ship movement has an important effect on plume rising, but it is often ignored in previous studies. We simulated the weakening effect caused by ship movement by considering the influence of four main parameters (wind speed, ship speed, flue gas exit velocity, and flue gas exit temperature) on the smoke plume rising height, using the computational fluid dynamics (CFD) model (PHOENICS version 6.0 CHAM, London, UK). The main parameters affecting the difference in plume rising height between stationary and moving sources for the same parameter settings are the wind speed and the ship speed. Therefore, we established two simplified calculation methods that corrected the flue gas exit velocity (Vexit′) and the flue gas exit temperature (T′) for approximately simulating the smoke plume rising height of the moving ship using the formula of a stationary ship. Verification cases indicated that the corrected Vexit′ (the average of relative error is 5.48%) and the corrected T′(the average of relative error is 60.07%) not only saved calculation time but also improved the simulation accuracy compared with the uncorrected stationary source scheme (the average of relative error is 135.38%). Of these correction methods, the scheme with corrected Vexit′ is more effective. The intention is to provide some references for the field experimentation of moving ship plume rising in different ports in the future and to further study the mechanism of moving ship plume rising.

Impact of the false intensification and recovery on the hydrological drought internal propagation

Understanding the influence factors of hydrological drought internal propagation (HDIP) is crucial for early detection of hydrological drought. However, the ‘false recovery’ (FR) during development of hydrological drought and ‘false intensification’ (FI) during the recovery stage were not considered. Here, the definitions of FR and FI were firstly introduced in detail. We define the FR that occurs during the drought intensification period and does not recover the hydrological drought to a normal pre-drought condition, and the FI that occurs during the drought recovery period and does not allow the hydrological drought to develop into maximum drought intensity. Then, we designed a numerical algorithm to assess the roles of the FR and FI during the hydrological drought by comparing two scenarios: 1) considering the FR and FI and 2) not including these two variables. The monthly streamflow and precipitation records with at least 40 years of data for five unregulated and rainfall-driven basins with minimal human activities, located in southern China, were taken for the case study. Three evaluation indicators were considered, i.e., the average of relative error (Ave.RE), coefficient of determination (R2), and the Nash-Sutcliffe efficiency (NSE) coefficient, to evaluate the differences in tracking effect of HDIP under considering FR (FI) and without considering FR (FI). Results showed that the FI and the FR influence the hydrological drought intensification and recovery by changing the drought severity. The higher the FR is, the lower severity and slower intensification the drought has. A greater FI leads to a hydrological drought that has larger severity and slower recovery. Considering the substantial influence of FR and FI can significantly improve tracking effect of HDIP. The Ave.RE decreased by 36.01% (24.98%) on average, R2 and NSE increased by 22.22% (14.06%) and 39.19% (24.02%) on average in the development (recovery) period of hydrological drought. The FR (FI) during the hydrological drought is mainly caused by the occurrence of short duration precipitation events (precipitation shortage) in the study basins. Our findings highlight the role of FI and FR in hydrological drought and provide valuable scientific insights for tracking hydrological drought in real time.

Multispectral Mid-Infrared Camera System for Accurate Stand-Off Temperature and Column Density Measurements on Flames.

Accurate measurement of temperature in flames is a challenging problem that has been successfully addressed by hyperspectral imaging. This technique is able to provide maps of not only temperature T (K) but also of column density Q (ppmm) of the main chemical species. Industrial applications, however, require cheaper instrumentation and faster and simpler data analysis. In this work, the feasibility and performance of multispectral imaging for the retrieval of T and Q in flames are studied. Both the hyperspectral and multispectral measurement methods are described and applied to a standard flame, with known T and Q, and to an ordinary Bunsen flame. Hyperspectral results, based on emission spectra with cm resolution, were found in previous works to be highly accurate, and are thus considered as the ground truth to compare with multispectral measurements of a mid-IR camera (3 to 5 m) with a six interference filter wheel. Maps of T and Q obtained by both methods show that, for regions with T K, the average of relative errors in multispectral measurements is ∼5% for T (and can be reduced to ∼2.5% with a correction based on a linear regression) and ∼20% for Q. Results obtained with four filters are very similar; results with two filters are also similar for T but worse for Q.

Online monitoring for floating raft structure displacement based on optimal placement of measuring points

The structure displacement of the raft of vibration isolation for ships is an important factor that affects shafting alignment accuracy and the safety of the equipment on the raft. In order to realize real-time monitoring of the raft structure displacement, which is the uncertain loadings and complex in shape, a measuring point placement strategy and an online monitoring method based on the displacement parameters to identify the displacement of the raft are proposed. FEM-based simulations for a prototyped raft have been conducted to obtain the displacement contour map. According to the displacement contour map based on displacement gradient and index evaluation, the measuring points have been combined and optimized. Displacement reconstruction principle based on a surface spline interpolation function method has been elaborated and derived. Structure displacement at any point can be obtained by a few measuring points. Finally, a case study of a certain type of floating raft is analyzed by the simulation analysis, and experimental research. The simulation and experimental results verify the validity of the measuring point placement strategy and the average of relative error with a value of less than 4% under different uncertain loadings. This method can effectively solve the problem of online monitoring of floating raft structure displacement under different changing loadings.

FBG-based online monitoring for uncertain loading-induced deformation of heavy-duty gantry machine tool base

An online monitoring approach for the uncertain loading-induced deformation of heavy-duty gantry machine tool base has been proposed by the combined use of Fiber Bragg Grating (FBG) sensors and a curvature-deformation algorithm. A placement strategy has been proposed to the deployment of these FBG sensors, ensuring to effectively sense the curvature. A cubic spline interpolation method has been applied to fully construct several continuous curvature functions. Deformation reconstruction principle based on these piecewise curvature functions has been elaborated and derived. FEM-based simulations for a prototyped base have been conducted to preliminary validate the effectiveness of the proposed approach. Experimental results further indicate that the maximum relative error of the reconstructed deformation values is decreased from 69.53% to 11% with an in-site calibration. The average of relative error with a value of less than 5.6% under different uncertain loadings, together with good consistency between the calculated deformation and detected values from the commercial sensors, have demonstrated the effectiveness and feasibility of the proposed approach. Several application experiments in a real gantry boring and milling machine tool base have been performed to further validate the feasibility of the proposed approach.

Simple and Improved Visible Spectrophotometric Method for Determination of Paracetamol Using Sodium Nitroprusside Chromogenic Reagent

A simple, rapid and improved visible spectrophotometric method has been proposed for determination of paracetamol (N-acetyl-p-aminophenol) in bulk drug. The experiment is based on the alkaline hydrolysis of paracetamol (PCT) to p-aminophenol (PAP) at elevated temperature and subsequent derivatization of PAP with sodium nitroprusside (SNP) at room temperature to produce an intense green colored N-nitrosyl-O-nitrosyl-p-aminophenol chromophore for direct determination of PCT at 685 nm. The molar absorptivity and Sandell's sensitivity are observed as 5.933x10 4 L.mol -1 .cm -1 and 0.0252 µg. cm -2 respectively for the chromophore. Beer's law is obeyed over the concentration range of 15-120 µg with linear regression equation as A= 0.009+0.003C (µg at 10 mL dilution). The percent recovery was found in the range 100.07-100.60%. The average of relative error and relative standard deviation are observed as 0.252% and 0.406% respectively. Reaction mechanism and reaction stoichiometry of the chromophoric reaction are discussed. The parameters with regard to determination of paracetamol by proposed method are optimized. Drugs like ibuprofen, aspirin and metformin do not interfere hence the proposed method is suitable for determination of PCT impurity in the said drugs.

Quantitative structure–retention relationship modeling of gas chromatographic retention times based on thermodynamic data

Thermodynamic parameters of ΔH(T0), ΔS(T0), and ΔCP for 156 compounds comprising alkanes, alkyl halides and alcohols were determined for a 5% phenyl 95% methyl stationary phase. The determination of thermodynamic parameters relies on a Nelder–Mead simplex optimization to rapidly obtain the parameters. Two methodologies of external and leave one out cross validations were applied to assess the robustness of the estimations of thermodynamic parameters. The largest absolute errors in predicted retention time across all temperature ramps and all compounds were 1.5 and 0.3s for external and internal sets, respectively. The possibility of an in silico extension of the thermodynamic library was tested using a quantitative structure–retention relationship (QSRR) methodology. The estimated thermodynamic parameters were utilized to develop QSRR models. Individual partial least squares (PLS) models were developed for each of the three classes of the molecules. R2 values for the test sets of all models across all temperature ramps were larger than 0.99 and the average of relative errors in retention time predictions of the test sets for alkanes, alcohols, and alkyl halides were 1.8%, 2.4%, and 2.5%, respectively.

PREDICTION OF NONLINEAR GRADIENT SIGNAL IN ION CHROMATOGRAPHY BASED ON “EXPERIMENT-FREE” METHODOLOGY

One of the strategies that might be applied in ion chromatographic (IC) multi-segment gradient optimization is the simplification of gradient profile and its approximation by nonlinear elution. This work describes the IC signal modeling strategy for linear and nonlinear gradients. The performance characteristics of developed models do not depend on the linearity of gradient profile, but rather on initial gradient of eluent competing ion concentration. Four different IC models were developed and tested, requiring three, two, or single experimental data points. Moreover, a model based on “experiment-free” methodology using standard column manufacturer quality assurance documents was developed. It is shown that all the developed models have good predictive ability that decreases by reducing the model complexity and number of experimental data required. However, even the “experiment-free” methodology offers reasonable performance characteristics (average of relative error 4.99%) and might be recommended for IC method development purposes.

Fluorescence quantification of tetracycline in the presence of quenching matrix effect by means of a four-way model

In this work, a four-way tensor is used to model the quenching effect in fluorescent measurements. By means of the analysis of excitation–emission matrices obtained in the determination of tetracycline in tea, which acts as quencher, it is shown as the impossibility to use a calibration, or an addition standard based on a three-way model. It is analysed the quencher multiplicative effect made on the tetracycline signal by means of an ANOVA. However, by arranging the experimental data in a four-way tensor, it is viable to perform a calibration based on the parallel factor analysis, PARAFAC, decomposition and a four-way partial least squares, 4-PLS, regression to quantify the tetracycline in the presence of the matrix quencher effect. 4-PLS calibration provides better results. In the range from 40 to 220 μg L −1 gives an average of relative errors in absolute value equal to 8.02% in prediction (3.40% in calibration). The repeatability as standard deviation in this range is 5.08 μg L −1 and the method is accurate, slope and intercept being statistically equal to 1 and 0, respectively when a regression calculated versus true concentration is performed. Moreover, it has a decision limit (CC α) of 13.87 μg L −1 for a probability of false positive, α, equal to 0.05 and a capability of detection (CC β) of 26.63 μg L −1 (for probabilities of false positive, α, false negative, β, equals to 0.05).

Application of different training methodologies for the development of a back propagation artificial neural network retention model in ion chromatography

AbstractThe reliability of predicted separations in ion chromatography depends mainly on the accuracy of retention predictions. Any model able to improve this accuracy will yield predicted optimal separations closer to the reality. In this work artificial neural networks were used for retention modeling of void peak, fluoride, chlorite, chloride, chlorate, nitrate and sulfate. In order to increase performance characteristics of the developed model, different training methodologies were applied and discussed. Furthermore, the number of neurons in hidden layer, activation function and number of experimental data used for building the model were optimized in terms of decreasing the experimental effort without disruption of performance characteristics. This resulted in the superior predictive ability of developed retention model (average of relative error is 0.4533%). Copyright © 2008 John Wiley & Sons, Ltd.

A Study on the Synthetic Characteristics of the Extracellular Polysaccharide (EPS) of Ganoderma lucidum Cultured in Batch Fermentation Using a Kinetic Model

The synthetic characteristics of the extracellular polysaccharide (EPS) of Ganoderma lucidum in batch fermentation were studied. The result showed that the production of EPS was partially growth-associated. The cell dry weight (CDW) and EPS reached 15.56 g·L −1 and 3.02 g·L −1, respectively. The yield of EPS to cell dry weight ( Y p/x) was 0.19. On the basis of the test results of batch fermentation, a kinetic model was proposed by using the Logistic equation for cell growth, the Luedeking–Piret equation for EPS production, and the Luedeking-piret-like equation for the consumption of glucose as substrate. The calculated results using these models were satisfactorily compared with the experimental data under various concentrations of glucose, and the average of relative errors was found to be not more than 5%. The kinetic model had practical guidance interesting in producing PES by Ganoderma lucidum.