新疆天山北坡常见盐生植物端元尺度光谱特征及识别

通过野外定点光谱采样,从端元尺度对天山北坡四种常见的盐生植物芨芨草、苦豆子、樟味藜、骆驼刺进行了光谱特征分析和种类识别。结果表明:从CARI和SIPI两个常用的叶绿素高光谱指数来看,骆驼刺的叶绿素含量和类胡萝卜素含量均较高,苦豆子虽然生长旺盛,由于受到光谱中花的因素影响,这两个指数值较低。苦豆子株冠郁闭度较高,其NDVI值高于其他三种植物。苦豆子和樟味藜的光谱位置参数较稳定,而芨芨草和骆驼刺则既存在BEP红移,也存在REP蓝移,红边和蓝边变化幅度较大。生长旺季中不同植物端元光谱曲线之间差异较小,存在明显的混合光谱现象,利用遥感常用的红/近红外特征空间难以准确区分樟味藜和骆驼刺。采用逐步多元判别分析,筛选出Rn,REP,Rg,MSAVI和CARI作为判别指标构建判别方程,芨芨草和樟味藜可以100%被识别,四种植物的判别总精度达92%以上。     

Statistical testing of optimality conditions in multiresponse simulation-based optimization

This article studies simulation-based optimization with multiple outputs. It assumes that the simulation model has one random objective function and must satisfy given constraints on the other random outputs. It presents a statistical procedure for testing whether a specific input combination (proposed by some optimization heuristic) satisfies the Karush–Kuhn–Tucker (KKT) first-order optimality conditions. The article focuses on “expensive” simulations, which have small sample sizes. The article applies the classic t test to check whether the specific input combination is feasible, and whether any constraints are binding; next, it applies bootstrapping (resampling) to test the estimated gradients in the KKT conditions. The new methodology is applied to three examples, which gives encouraging empirical results.     

异辛醇中酶催化高效合成阿莫西林的研究

通过比较6种有机溶剂作为反应介质时对阿莫西林合成的影响,发现反应介质在保持酶的催化活性和稳定性方面发挥着非常重要的作用,确定异辛醇为酶催化合成阿莫西林的反应介质.通过研究不同温度下异辛醇中酶催化合成阿莫西林的时间曲线,确定了最佳反应温度和反应时间,通过对底物浓度和酶浓度进行响应面优化,最终得到阿莫西林合成的最优反应条件,在最优条件下可得到91.37%的最大阿莫西林产率.     

Parallel radial basis function methods for the global optimization of expensive functions

We introduce a master–worker framework for parallel global optimization of computationally expensive functions using response surface models. In particular, we parallelize two radial basis function (RBF) methods for global optimization, namely, the RBF method by Gutmann [Gutmann, H.M., 2001a. A radial basis function method for global optimization. Journal of Global Optimization 19(3), 201–227] (Gutmann-RBF) and the RBF method by Regis and Shoemaker [Regis, R.G., Shoemaker, C.A., 2005. Constrained global optimization of expensive black box functions using radial basis functions, Journal of Global Optimization 31, 153–171] (CORS-RBF). We modify these algorithms so that they can generate multiple points for simultaneous evaluation in parallel. We compare the performance of the two parallel RBF methods with a parallel multistart derivative-based algorithm, a parallel multistart derivative-free trust-region algorithm, and a parallel evolutionary algorithm on eleven test problems and on a 6-dimensional groundwater bioremediation application. The results indicate that the two parallel RBF algorithms are generally better than the other three alternatives on most of the test problems. Moreover, the two parallel RBF algorithms have comparable performances on the test problems considered. Finally, we report good speedups for both parallel RBF algorithms when using a small number of processors.     

Rs中响应曲面模型的稳健设计

本文运用再生核Hhilbert空间方法研究R^s中响应曲面模型的稳健设计问题。我们假设模型偏差包括由多元Hermite多项式高阶项产生的效应，如果偏差大，设计点应该布于布点附近，否则，设计点应该适当散开，所求设计是正交不变的，而且关于模型偏差是稳健的。     

弹性介质中圆柱壳动力响应研究的现状和展望

一、引言在地震动情况下,地下结构与地面结构相比较其动力响应是十分不同的。以桥梁和水堤为例,对这类结构的设计,水平惯性力是一个极为重要的因素。可是,对于地下结构,以埋管为例,惯性荷载主要由其周围的土介质所承受。地下管道系统的地震破坏,     

Response of Uncertain Nonlinear Vibration Systems with 2D Matrix Functions

This paper extends the response of uncertain nonlinear vibration systems to vector-valued and matrix-valued functions. Random variables and system derivatives are conveniently arranged into 2D matrices. The method is based on a second order expansion of the governing equations and matrix calculus, Kronecker algebra are used in the mathematical development. The results derived are easily amenable to computational procedures.     

A Galerkin Approach for Power Spectrum Determination of Nonlinear Oscillators

A numerical method to estimate spectral properties of nonlinear oscillators with random input is presented. The stationary system response is expanded into a trigonometric Fourier series. A set of nonlinear algebraic equations, solved by Newtons method, leads to the determination of the unknown Fourier series coefficients of single samples of the response process. For cubic polynomial nonlinearities, closed-form expressions are used to find the nonlinear terms at each step of the solution scheme. Further, a simple procedure yields an approximation of an arbitrary nonlinearity by a cubic polynomial. Power spectral density estimates for the response process are constructed by averaging the square modulus of the computed Fourier coefficients over various samples or by means of well-established smoothing techniques of spectral analysis. Two applications are presented illustrating the effectiveness of the method as compared to statistical linearization and digital Monte-Carlo simulation.     

Optimization of microwave‐assisted extraction for six inorganic and organic arsenic species in chicken tissues using response surface methodology

Response surface methodology was applied to optimize the parameters for microwave‐assisted extraction of six major inorganic and organic arsenic species (As(III), As(V), dimethyl arsenic acid, monomethyl arsenic acid, p‐arsanilic acid, and roxarsone) from chicken tissues, followed by detection using a high‐performance liquid chromatography with inductively coupled mass spectrometry detection method, which allows the simultaneous analysis of both inorganic and organic arsenic species in the extract in a single run. Effects of extraction medium, solution pH, liquid‐to‐solid ratio, and the temperature and time of microwave‐assisted extraction on the extraction of the targeted arsenic species were studied. The optimum microwave‐assisted extraction conditions were: 100 mg of chicken tissue, extracted by 5 mL of 22% v/v methanol, 90 mmol/L (NH₄)₂HPO₄, and 0.07% v/v trifluoroacetic acid (with pH adjusted to 10.0 by ammonium hydroxide solution), ramping for 10 min to 71°C, and holding for 11 min. The method has good extraction performance for total arsenic in the spiked and nonspiked chicken tissues (104.0 ± 13.8% and 91.6 ± 7.8%, respectively), except for the ones with arsenic contents close to the quantitation limits. Limits of quantitation (S/N = 10) for As(III), As(V), dimethyl arsenic acid, monomethyl arsenic acid, p‐arsanilic acid, and roxarsone in chicken tissues using this method were 0.012, 0.058, 0.039, 0.061, 0.102, and 0.240 mg/kg (dry weight), respectively.     

Étude des temps de chauffage et de refroidissement des alliages à mémoire de forme (AMF)Heating and cooling time studies of shape memory alloys (SMA)

The knowledge of response times of active material is essential for their efficient use as actuators. In this paper the heating and cooling times of a shape memory alloy wire (NiTi) under a constant load are predicted by the integration of the corresponding heat equation. The comparison with a ‘fictitious’ material with the same material characteristics but without phase transformation shows that the response times are longer for the SMA (around 2.7 times for heating and 1.5 times for cooling). To cite this article: N. Chaillet et al., C. R. Mecanique 332 (2004).