先进的离子束热处理技术和工业应用

评述了离子束技术的发展和应用,特别针对离子束多功能综合加工技术的发展进行了评论.这种技术已经成为独具特色的热处理技术.该技术属于低消耗、高产出、高效率和无污染的绿色加工技术.评述了这一技术的未来发展方向.     

Evaluation of tile–wall bonding integrity based on impact acoustics and support vector machine

It is well recognized that the impact-acoustic emissions contain information that can indicate the presence of the adhesive defects in the bonding structures. In our previous papers, artificial neural network (ANN) was adopted to assess the bonding integrity of the tile–walls with the feature extracted from the power spectral density (PSD) of the impact-acoustic signals acting as the input of classifier. However, in addition to the inconvenience posed by the general drawbacks such as long training time and large number of training samples needed, the performance of the classic ANN classifier is deteriorated by the similar spectral characteristics between different bonding status caused by abnormal impacts. In this paper our previous works was developed by the employment of the least-squares support vector machine (LS-SVM) classifier instead of the ANN to derive a bonding integrity recognition approach with better reliability and enhanced immunity to surface roughness. With the help of the specially designed artificial sample slabs, experiments results obtained with the proposed method are provided and compared with that using the ANN classifier, demonstrating the effectiveness of the present strategy.     

子空间半监督Fisher判别分析

Fisher判别分析寻找一个使样本数据类间散度与样本数据类内散度比值最大的子空间, 是一种很流行的监督式特征降维方法. 标注样本数据所属的类别通常需要大量的人工, 消耗大量的时间, 付出昂贵的成本. 为了解决同时利用有类别信息的样本数据和没有类别信息的样本数据用于寻找降维子空间的问题, 我们提出了一种子空间半监督Fisher判别分析方法. 子空间半监督Fisher判别分析寻找这样一个子空间, 这个子空间即保留了从有类别信息的样本数据中学习的类别判别结构, 也保留了从有类别信息的样本数据和没有类别信息的样本数据中学习的样本结构信息. 我们还推导了基于核的子空间半监督Fisher判别分析方法. 通过人脸识别实验验证了本文算法的有效性.     

超载作用下软土盾构隧道横向变形机理及控制指标研究

隧道横向变形直接关系到结构安全,首先采用数值模拟方法研究了地面压载、土体侧向压力系数和土体抗力系数对隧道横向变形发展的影响,研究了隧道横向变形随压载的变化发展规律,建立了隧道直径变化和混凝土受力、螺栓受力以及接头张开量之间的关系,提出了以隧道直径变化作为隧道横向结构性态发展的判定指标;根据隧道横向变形发展规律,利用隧道结构变形发展过程中的结构几何特征,建立了隧道变形量发展的几何简易分析方法,利用该方法直接测量隧道直径变化就可以判定隧道变形状态,为隧道结构安全评价提供了十分简单有效的手段。     

DRIFTS study of ammonia activation over CaO and sulfated CaO for NO reduction by NH3

CaO catalyzes NH(3) oxidation, while sulfated CaO catalyzes NO reduction by NH(3) in the presence of O(2), and the adsorption and transformation of ammonia over CaO and sulfated CaO has been investigated by in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) to understand their catalytic mechanism. It has been found that ammonia is first adsorbed over Lewis or Bro?nsted acid sites, and later undergoes hydrogen abstraction giving rise to either NH(2) amide or NH imide intermediates. The intermediates react with NO or lattice O to produce N(2) or NO. Comparing the DRIFTS of NH(3) adsorption over CaO and sulfated CaO, it is obvious that ammonia adsorbed over CaO is activated mainly in NH form apt to react with surface oxygen to produce NO, while ammonia adsorbed over sulfated CaO is activated mainly in NH(2) form apt to reduce NO. The DRIFTS results agree with experimental data and explain the catalytic mechanisms of CaO and sulfated CaO.     

A semi-parametric approach for mixture models: Application to local false discovery rate estimation

A procedure to estimate a two-component mixture model where one component is known is proposed. The unknown part is estimated with a weighted kernel function. The weights are defined in an adaptive way. The convergence to a unique solution of our estimation procedure is proven. The procedure is compared with two classical approaches using simulation. In addition, the results obtained are applied to multiple testing procedure in order to estimate the posterior population probabilities and the local false discovery rate.     

Implications of invariance and uncertainty for local structure analysis filter sets

The paper discusses which properties of filter sets used in local structure estimation that are the most important. Answers are provided via the introduction of a number of fundamental invariances. Mathematical formulations corresponding to the required invariances leads up to the introduction of a new class of filter sets termed loglets. Loglets are polar separable and have excellent uncertainty properties. The directional part uses a spherical harmonics basis. Using loglets it is shown how the concepts of quadrature and phase can be defined in n-dimensions. It is also shown how a reliable measure of the certainty of the estimate can be obtained by finding the deviation from the signal model manifold.Local structure analysis algorithms are quite complex and involve a lot more than the filters used. This makes comparisons difficult to interpret from a filter point of view. To reduce the number ‘free’ parameters and target the filter design aspects a number of simple 2D experiments have been carried out. The evaluation supports the claim that loglets are preferable to other designs. In particular it is demonstrated that the loglet approach outperforms a Gaussian derivative approach in resolution and robustness.     

A modified solution of radial subgrade modulus for a circular tunnel in elastic ground

In models based on Winkler springs for tunnel lining design, designers always face the difficulty of selecting appropriate values for the radial subgrade modulus (k_r). The widely used solution k_r for a circular tunnel in elastic ground proposed by Wood (1975) was found to be applicable only when the tunnel radial deformation is oval-shaped. On the basis of the Wood׳s solution, this note presents a general solution for k_r when the radial deformation of the tunnel is described by a Fourier series. This modified Wood׳s solution of k_r using compatible stress functions is validated by a numerical example. The modified solution for the example shows good consistency with the original Wood׳s solution when the tunnel becomes an oval shape with deformations. The example indicates that the magnitude of k_r is significantly affected by the distribution shape of the tunnel radial deformation. The value of k_r is no longer a constant value around the tunnel when the tunnel deforms into a general shape described by a Fourier series. It is quite different from the value of k_r for a distribution shape described by a single Fourier term, i.e. one involving a single frequency. The application of a general solution for k_r is illustrated by a design case using a bedded beam model.     

基于改进可拓学第三创造法的产品创新设计

针对可拓设计方法中第三创造法对现有产品模型的建立以及缺点列举中的不足,提出建立产品事元模型,并引入功能分析与因果链分析方法的改进第三创造法。该方法利用功能分析方法对产品的缺点进行分析,并通过因果链分析方法找出引起产品缺点的深层原因,以形成关键问题,最后运用第三创造法对关键问题的改进,得到产品创新设计方案。应用改进后的第三创造法,对现有普通断线钳进行创新设计并生成了多种不同的设计方案,对这些方案进行优度评价,选取优度最高者作为最终设计。设计结果验证了该方法的可行性和有效性。     

Supercapacitive behaviors of activated mesocarbon microbeads coated with polyaniline

The polyaniline/activated mesocarbon microbeads (PANI/ACMB) composites are prepared by in situ chemical oxidation polymerization. Fourier infrared spectroscopy (FTIR), scanning electron microscope (SEM) and transmission electron microscope (TEM) have been utilized to characterize the structure and morphology of PANI/ACMB composites. It has been found that PANI is uniformly deposited on the surface of the ACMB to form the leechee-like morphology. The supercapacitive behaviors of the PANI/ACMB composites are investigated with cyclic voltammetry (CV), galvanostatic charge/discharge and cycle life measurements. The results obtained from cyclic voltammograms show that the composites have a maximum specific capacitance of 433.75 F g⁻¹. Moreover, the electrochemical performance of the coin supercapacitor used PANI/ACMB composites as electrode active material represents both high specific capacitance and excellent cycle stability, indicating that the PANI/ACMB composites will be a kind of potential electrode active materials with excellent specific capacitance and enhanced cycle life for application in high performance supercapacitors.