Detailed Response Characteristics Research Articles

Prediction of the Near-Infrared Absorption Spectrum of Single-Walled Carbon Nanotubes Using a Bayesian Regularized Back Propagation Neural Network Model

DNA-wrapped single-walled carbon nanotubes (DNA-SWCNTs) in stable dispersion are expected to be used as biosensors in the future, because they have the property of absorption of light in the near infrared (NIR) region, which is safe for the human body. However, this practical application requires the understanding of the DNA-SWCNTs’ detailed response characteristics. The purpose of this study is to predict, in detail, the response characteristics of the absorption spectra that result when the antioxidant catechin is added to oxidized DNA-SWCNTs, from a small amount of experimental data. Therefore, in the present study, we predicted the characteristics of the absorption spectra of DNA-SWCNTs using the Bayesian regularization backpropagation neural network (BRBPNN) model. The BRBPNN model was trained with the catechin concentration and initial absorption peaks as inputs and the absorption spectra after catechin addition as outputs. The accuracy of the predicted absorption peaks and wavelengths after the addition of catechin, as predicted by the BRBPNN model, was within 1% of the error of the experimental data. By inputting the catechin concentrations under hundreds of conditions into this BRBPNN model, we were able to obtain detailed prediction curves for the absorption peaks. This method has the potential to help to reduce the experimental costs and improve the efficiency of investigating the properties of high-cost materials such as SWCNTs.

Characteristics of stick-slip oscillations in dry friction backward whirl of piecewise smooth rotor/stator rubbing systems

Abstract Self-excited dry friction backward whirl, or shortly denoted as DFBW, are the most destructive rotor/stator rubbing response. From the point of view of sliding bifurcations, this paper first unveils the characteristics of stick-slip oscillations exhibited in the response of self-excited dry friction backward whirl. By studying a four-dimensional piecewise smooth rotor/stator rubbing system, which has a switching manifold defined by the zero relative velocity on the rubbing point, three types of sliding regions on the curved hypersurface of the switching manifold are identified according to the characters of the two discontinuous vector fields near it. The influence of the system parameters on the stick-slip transitions in DFBW is also explored, which shows the interplay of the different parameters and reveals the phenomenon observed experimentally. On basis of the relation between the existence boundaries of DFBW and the characters of sliding motions on it, a new way, from the theory of non-smooth dynamics, to analytically derive the existence condition of the self-excited dry friction backward whirl (DFBW) is presented and coincident with the existing formula in the literature. The work provides a deeper insight into the more detailed response characteristics in the self-excited dry friction backward whirl of rotor/stator rubbing systems.

Extension of a new approach towards accurate stress analysis of laminates subjected to thermomechanical loading

The stress-analysis method presented in this paper is based on the extension of a successful, two-dimensional generalised laminate theory towards consideration of thermo-mechanical deformation effects. Like its conventional counterparts, that generalised equivalent-single-layer (ESL) laminate model makes use of a fixed and small number of unknowns. Its success is, however, based on the incorporation into its approximate, thermo-mechanical displacement field of the exact elasticity distributions available for corresponding simply supported structural components. With this incorporation, the ESL laminate model acquires benefits of a corresponding layer-wise theory. Most importantly, the proposed ESL theory and three-dimensional thermo-elasticity yield identical stress distributions for simply supported laminates. For other sets of edge boundary conditions, solutions and therefore detailed response characteristics that are based on such an ESL theory are accurate away of the laminate edges. If necessary, accuracy of detailed response characteristics can be further improved on a predictor–corrector basis.

Intercomparisons and Aerosol Calibrations of 12 Commercial Integrating Nephelometers of Three Manufacturers

Abstract This study determined measured and Mie-calculated angular signal truncations for total and backscatter TSI, Inc., nephelometers, as a function of wavelength and for particles of known size and composition. Except for the total scattering channels, similar agreements as in a previous study of measured and calculated truncations were derived for submicrometer test aerosols. For the first time, instrument responses were also determined for supermicrometer test aerosols up to 1.9 μm in geometric mean diameter. These supermicrometer data confirm the theoretical predictions of strong angular truncations of the total scatter signals in integrating nephelometers due to the limited range of measured forward scattering angles. Truncations up to 60% were determined for the largest measured particles. Rough empirical truncation corrections have been derived from the calibration data for Radiance Research and Ecotech nephelometers for which no detailed response characteristics exist. Intercomparisons of the nephelometers measuring urban atmospheric aerosols yield average deviations of the slope from a 1:1 relation with a TSI reference nephelometer of less than 7%. Average intercepts range between +0.53 and −0.19 Mm−1. For the Radiance Research and Ecotech nephelometers ambient regressions of the Radiance Research and Ecotech instruments with the TSI nephelometer show larger negative intercepts, which are attributed to their less well characterized optics.

An assessment of five modeling approaches for thermo-mechanical stress analysis of laminated composite panels

A study is made of the effects of variation in the lamination and geometric parameters, and boundary conditions of multi-layered composite panels on the accuracy of the detailed response characteristics obtained by five different modeling approaches. The modeling approaches considered include four two-dimensional models, each with five parameters to characterize the deformation in the thickness direction, and a predictor-corrector approach with twelve displacement parameters. The two-dimensional models are first-order shear deformation theory, third-order theory; a theory based on trigonometric variation of the transverse shear stresses through the thickness, and a discrete layer theory. The combination of the following four key elements distinguishes the present study from previous studies reported in the literature: (1) the standard of comparison is taken to be the solutions obtained by using three-dimensional continuum models for each of the individual layers; (2) both mechanical and thermal loadings are considered; (3) boundary conditions other than simply supported edges are considered; and (4) quantities compared include detailed through-the-thickness distributions of transverse shear and transverse normal stresses. Based on the numerical studies conducted, the predictor-corrector approach appears to be the most effective technique for obtaining accurate transverse stresses, and for thermal loading, none of the two-dimensional models is adequate for calculating transverse normal stresses, even when used in conjunction with three-dimensional equilibrium equations.

Characteristics of Nb/Al-AlOx/Al/Nb tunnel junction for X-ray of 5 to 15keV

This paper provides detailed response characteristics of a Nb/Al-AlOx/Al/Nb superconducting tunnel junction for X-ray of 5keV to 15keV investigated by using synchrotron radiation.

Assessment of computational models for sandwich panels and shells

A study is made of the effects of variation in the material and geometric parameters of curved sandwich panels on the accuracy of the static response predicted by nine different modeling appraoches based on two-dimensional shell theories. The standard of comparison is taken to be the exact three-dimensional thermoelasticity solutions, and the quantities compared include gross response characteristics (e.g. strain energy components, average through-the-thickness displacements and rotations); detailed, through-the-thickness distributions of displacements and stresses; and sensitivity coefficients of the response quantities (derivatives of response quantities with respect to material and geometric parameters of the sandwich structure). Extensive numerical studies are conducted to assess the accuracy of both the global and detailed response characteristics and their sensitivity coefficients obtained by nine two-dimensional modeling approaches. For accurate determination of detailed through-the-thickness distributions such as transverse stresses, either high-order discrete three-layer models or predictor-corrector approaches are required. The potential of predictor-corrector approaches for predicting the thermomechanical response of sandwich panels and shells with complicated geometry is also discussed.

Dynamic Response of a Circular Cylinder Subjected to Liquid Cross Flow

This paper describes a series of experimental investigations of single tubes subjected to crossflow. The experiments have two distinct features: 1–the damping in the lift and drag direction is measured as a function of reduced flow velocity; 2–the detailed response characteristics of the tube are obtained at various reduced flow velocities. The analytical model is also presented to correlate with the experimental data. The results of this study provide some additional insight into the response characteristics of a single tube subjected to liquid cross flow including, among others, flow-velocity dependent damping and “lock-in” region of tube motion in the drag direction.

Transmission of Random Sound and Vibration through a Rectangular Double Wall

The existence of many modes of vibration in a complex system makes a detailed classical analysis almost intractable. However, when excited by broad-band random noise, the detailed response characteristics may be overlooked and statistical properties such as mean-square values and power spectra provide a measure of the vibration. The existence of classes of similarly excited modes allows theories of room acoustics and thermodynamics to be applied successfully. For sound transmission through a rectangular double wall, this technique gives results that agree within experimental error of measured transmission loss, much better than do conventional loss estimates. Both theory and experiment confirm that the product of modal density, average joint acceptance of the first panel, and the ratio of radiation to total resistance of the second panel are the most important characteristics in determining the transmission characteristics of the wall.