2D Burgers equation with large Reynolds number using POD/DEIM and calibration

Model order reduction of the two‐dimensional Burgers equation is investigated. The mathematical formulation of POD/discrete empirical interpolation method (DEIM)‐reduced order model (ROM) is derived based on the Galerkin projection and DEIM from the existing high fidelity‐implicit finite‐difference full model. For validation, we numerically compared the POD ROM, POD/DEIM, and the full model in two cases of Re = 100 and Re = 1000, respectively. We found that the POD/DEIM ROM leads to a speed‐up of CPU time by a factor of O(10). The computational stability of POD/DEIM ROM is maintained by means of a careful selection of POD modes and the DEIM interpolation points. The solution of POD/DEIM in the case of Re = 1000 has an accuracy with error O(10^?3) versus O(10^?4) in the case of Re = 100 when compared with the high fidelity model. For this turbulent flow, a closure model consisting of a Tikhonov regularization is carried out in order to recover the missing information and is developed to account for the small‐scale dissipation effect of the truncated POD modes. It is shown that the computational results of this calibrated ROM exhibit considerable agreement with the high fidelity model, which implies the efficiency of the closure model used. Copyright © 2016 John Wiley & Sons, Ltd.     

一种不同地面分辨率图像的拼接算法

航空遥感监测中变焦镜头的广泛应用以及飞行高度的变化会获得不同地面分辨率的航空影像,因此为了实时监控到飞行区域的整体情况,需要对不同地面分辨率的图像进行拼接。提出了针对不同地面分辨率图像进行拼接的方法。首先用四分法对图像进行分割,检测变化倍率,选择配准策略;然后用基于加速鲁棒性特征(Speeded-Up Robust Features,SURF)的算法对相邻图像进行拼接。获得了焦距变化从高倍过渡到低倍,或从低倍过渡到高倍的拼接图像。通过航空变焦模拟影像的拼接实验和地面变焦影像的拼接实验表明,该方法能够对不同地面分辨率的图像进行拼接,且拼接结果均以高分辨率为基准。     

Ethylenically unsaturated polycarbosiloxanes for novel silicone hydrogels: synthesis,end‐group analysis,contact lens formulations,and structure–property correlations

A series of novel mono‐ethylenically unsaturated polycarbosiloxanes macromonomers as compatibilizer materials for soft silicon hydrogels were prepared from the anionic ring‐opening polymerization (AROP) of 2,2,5,5‐tetramethyl‐2,5‐disila‐1‐oxacyclopentane followed by methacrylation. The characterization was performed by end‐group analysis and included the determination of molecular weight, molecular weight distributions, end‐group functionality, and impurity profiles using gas chromatography‐mass spectrometry, gel permeation chromatography, nuclear magnetic resonance, and matrix‐assisted laser desorption/ionization time of flight mass spectrometry. The synthetic procedure was optimized to minimize the formation of any dimer that would have the potential to act as a low molecular weight cross linker. In addition, the novel di‐ethylenically unsaturated polycarbosiloxanes were synthesized by cationic polymerization. Use of these silicone derivatives was explored in the formulation of contact lenses, and the structure–property relationship was examined. When copoymerized with hydrophilic monomers, these were able to give transparent and wettable films with desired properties, particularly a low moduli for contact lenses. Contact lens with high modulus is often shown to impart a higher degree discomfort when worn upon the eye. It was clear from the structure–property relationship that the modulus and the tensile strength of the formulated material depend on the nature and length of the polycarbosiloxane used and may be tuned for the purpose as needed. Copyright © 2013 John Wiley & Sons, Ltd.     

Carbon dots with strong excitation-dependent fluorescence changes towards pH. Application as nanosensors for a broad range of pH

In this study, preparation of novel pH-sensitive N-doped carbon dots (NCDs) using glucose and urea is reported. The prepared NCDs present strong excitation-dependent fluorescence changes towards the pH that is a new behavior from these nanomaterials. By taking advantage of this unique behavior, two separated ratiometric pH sensors using emission spectra of the NCDs for both acidic (pH 2.0 to 8.0) and basic (pH 7.0 to 14.0) ranges of pH are constructed. Additionally, by considering the entire Excitation–Emission Matrix (EEM) of NCDs as analytical signal and using a suitable multivariate calibration method, a broad range of pH from 2.0 to 14.0 was well calibrated. The multivariate calibration method was independent from the concentration of NCDs and resulted in a very low average prediction error of 0.067 pH units. No changes in the predicted pH under UV irradiation (for 3 h) and at high ionic strength (up to 2 M NaCl) indicated the high stability of this pH nanosensor. The practicality of this pH nanosensor for pH determination in real water samples was validated with good accuracy and repeatability.     

Simultaneous Determination of Acetaminophen and Phenobarbital in Suppositories by Partial Least-Squares Spectrophotometric Calibration

Abstract

The use of partial least-squares spectrophotometric calibration for the simultaneous determination of suppositories in a multicomponent formulation is presented. This method is applied to the deternination of acetaminophen and phenobarbital in suppository preparations. The results show that these components in a molar ratio of about 61:1 in suppositories have been determined simultaneously with high precision.     

Efficient computation of operator‐type response sensitivities for uncertainty quantification and predictive modeling: illustrative application to a spent nuclear fuel dissolver model

This work honors the 75th birthday of Professor Ionel Michael Navon by presenting original results highlighting the computational efficiency of the adjoint sensitivity analysis methodology for function‐valued operator responses by means of an illustrative paradigm dissolver model. The dissolver model analyzed in this work has been selected because of its applicability to material separations and its potential role in diversion activities associated with proliferation and international safeguards. This dissolver model comprises eight active compartments in which the 16 time‐dependent nonlinear differential equations modeling the physical and chemical processes comprise 619 scalar and time‐dependent model parameters, related to the model's equation of state and inflow conditions. The most important response for the dissolver model is the time‐dependent nitric acid in the compartment furthest away from the inlet, where measurements are available at 307 time instances over the transient's duration of 10.5 h. The sensitivities to all model parameters of the acid concentrations at each of these instances in time are computed efficiently by applying the adjoint sensitivity analysis methodology for operator‐valued responses. The uncertainties in the model parameters are propagated using the above‐mentioned sensitivities to compute the uncertainties in the computed responses. A predictive modeling formalism is subsequently used to combine the computational results with the experimental information measured in the compartment furthest from the inlet and then predict optimal values and uncertainties throughout the dissolver. This predictive modeling methodology uses the maximum entropy principle to construct an optimal approximation of the unknown a priori distribution for the a priori known mean values and uncertainties characterizing the model parameters and the computed and experimentally measured model responses. This approximate a priori distribution is subsequently combined using Bayes' theorem with the “likelihood” provided by the multi‐physics computational models. Finally, the posterior distribution is evaluated using the saddle‐point method to obtain analytical expressions for the optimally predicted values for the parameters and responses of both multi‐physics models, along with corresponding reduced uncertainties. This work shows that even though the experimental data pertains solely to the compartment furthest from the inlet (where the data were measured), the predictive modeling procedure used herein actually improves the predictions and reduces the predicted uncertainties for the entire dissolver, including the compartment furthest from the measurements, because this predictive modeling methodology combines and transmits information simultaneously over the entire phase‐space, comprising all time steps and spatial locations. Copyright © 2016 John Wiley & Sons, Ltd.     

Determination of Some Organochlorine Compounds in the Atmosphere

Abstract

Since plastics are suspected to adsorb orthophosphate, disposable-tip pipettes have been checked to determine their ability to be used in orthophosphate calibration. No adsorption has been detected through an experiment of standard preparation with and without changing the pipette tip. That is, the pipettes appear to be convenient for orthophosphate calibration.     

密度检定液配制及注意事项

根据密度计的工作和检定原理,介绍各种密度检定液的配制方法及注意事项。针对硫酸氢乙酯检定液难以配制问题,着重介绍了检定液的配制过程,通过对不同浓度酒精液配制的硫酸氢乙酯校准密度计的比较实验,说明了不同体积分数酒精液配制的硫酸氢乙酯对校准结果的影响。     

线型光束可燃气体探测器的校准

介绍线型光束可燃气体探测器的的校准方法。对线型光束可燃气体探测器的示值误差、报警功能、响应时间、光强衰减性能和抗日光干扰性能等主要计量特性及技术指标进行校准,给出了各主要计量特性的校准条件、试验设备和具体校准方法。对两台线型光束可燃气体探测器进行了校准,其示值误差用相对误差表示分别为–5%和4%,用引用误差表示分别为–4%FS和3%FS。经验证,上述结果均未超出设定指标,响应时间等其它主要计量特性也符合方法要求。该方法校准后的计量特性及技术指标较为合理,校准方法切实可行,可以用于线型光束可燃气体探测器的校准。     

Determination of Iron in Calf Serum Using Bathophenanthroline and Thermal Lens Spectrometry

ABSTRACT

Thermal lens spectrometry has been used for the determination of iron in calf serum. The method is based on dissociation of Fe³⁺ from proteins, reduction of Fe³⁺ to Fe²⁺ and formation of a coloured complex between Fe²⁺ and bathophenanthroline. Contrary to the spectrophotometric method, it is shown that thermal lens spectrometry is less sensitive to scattering caused by the presence of small particles remaining in the test solution after the deproteinization step. The background signal is very small and the response is only slightly dependent on the amount of scattering particles. The method is reliable, sensitive and reproducible. The limit of detection for iron is 4 ppb and the relative standard deviation is around 2%. It is expected that the volume of serum sample necessary for an analysis can be reduced to less than 100 μl.