Regioselective opening of an oxirane system with trifluoroacetic anhydride. A general method for the synthesis of 2-monoacyl- and 1,3-symmetrical triacylglycerols

A trifluoroacetic anhydride-catalyzed opening of the oxirane system of glycidyl esters with a simultaneous migration of the acyl group provides a new, efficient entry to either 2-monoacylglycerols (2-MAG) or 1,3-symmetrical triglycerides (1,3-STG) as potential prodrug frameworks.     

Simple and fast rail wear measurement method based on structured light

In this paper, a fast and accurate rail wear measurement method based on simple equipments is presented. The inner rail profile is measured by a line structured light vision sensor. Using the centers of the big and small circle from the rail waist profile as control points, the measured rail profile is registered to the reference profile. The rail wear, including the vertical and horizontal rail wear, is computed by comparing the registered measured profile with the reference profile. The method has three key contributions: (1) the rail waist light stripe center points in the images are located fast and accurately by first tracking the region containing the rail waist light stripe using the Kalman filter and then computing the sub-pixel precision image coordinates by Hessian matrix at pixels. (2) The rail waist profile is segmented automatically into arcs of big and small circles by thresholding the normal angle curve of the measured rail waist profile. The centers of the two circles are used as control points for registering the measured rail profile to the reference profile. (3) The fast location of rail wear points in the images is realized by projecting the rail wear constraint points to the image, which simplifies the problem of computing rail wear from 2d image processing to 1d searching along the line segment connecting two rail wear constraint points. Experiments show that the proposed method can achieve 500 fps measurement frequency. At a train speed of 350 km/h, the interval between two consecutive measurements is about 190 mm. The system is tested on a real running train, and the measurement results are compared with those rail wear measured manually by special gage. The RMS errors of vertical and horizontal rail wears are 0.34 and 0.30 mm, respectively.     

Deposition of Aerosol Nanoparticles on Flat Substrate Surfaces

The deposition process in a homogeneous electric field, and the subsequent microscopic arrangement of charged, metallic aerosol nanoparticles in the size range of 30 nm on flat substrate surfaces is described. The first aspect of the investigation is the transfer of the particles from a three-dimensional distribution in the gas phase into their arrangement on the substrate surface, in dependence on particle-particle interactions and on Brownian motion. The theoretical results obtained with a trajectory model are compared with experimental results obtained by scanning electron microscope investigation of the deposition patterns. The second aspect of the investigation is the nanostructured arrangement of nanoparticles by means of inhomogeneous electric microfields. We demonstrate a parallel process for the transfer of charge patterns on oxidized silicon surfaces followed by the deposition of monodisperse singly charged nanoparticles, which allows the creation of particle arrangements reaching from 100 nm resolution up to structures in the upper micrometer range. The charge patterns are transferred using a polydimethylsiloxane (PDMS)-stamp, which is covered with a metal layer.     

模糊合作博弈Shapley值的模糊结构元表示

将模糊数学理论应用到合作博弈中,用精确的数学表达式来表示实际生活中的模糊事件,又将模糊结构元理论应用到模糊合作博弈中,将模型中的模糊数用模糊结构元表示,以往基于扩张原理的模糊Shapley值的隶属函数非常复杂,本文给出其求解方法,使其得到解析表达.通过一个算例,来说明该模型的具体应用,与支付函数用区间数表示等研究方法相比较,该模型不仅保证了隶属函数的连续性,还给出区间上每个取值的隶属度,可以为管理者提供更精确的信息.     

Sparse spectral clustering method based on the incomplete Cholesky decomposition

A novel sparse spectral clustering method using linear algebra techniques is proposed. Spectral clustering methods solve an eigenvalue problem containing a graph Laplacian. The proposed method exploits the structure of the Laplacian to construct an approximation, not in terms of a low rank approximation but in terms of capturing the structure of the matrix. With this approximation, the size of the eigenvalue problem can be reduced. To obtain the indicator vectors from the eigenvectors the method proposed by Zha et al. (2002) [26], which computes a pivoted LQ$LQ$ factorization of the eigenvector matrix, is adapted. This formulation also gives the possibility to extend the method to out-of-sample points.     

Improving an interior-point approach for large block-angular problems by hybrid preconditioners

The computational time required by interior-point methods is often dominated by the solution of linear systems of equations. An efficient specialized interior-point algorithm for primal block-angular problems has been used to solve these systems by combining Cholesky factorizations for the block constraints and a conjugate gradient based on a power series preconditioner for the linking constraints. In some problems this power series preconditioner resulted to be inefficient on the last interior-point iterations, when the systems became ill-conditioned. In this work this approach is combined with a splitting preconditioner based on LU factorization, which works well for the last interior-point iterations. Computational results are provided for three classes of problems: multicommodity flows (oriented and nonoriented), minimum-distance controlled tabular adjustment for statistical data protection, and the minimum congestion problem. The results show that, in most cases, the hybrid preconditioner improves the performance and robustness of the interior-point solver. In particular, for some block-angular problems the solution time is reduced by a factor of 10.     

Line structured light vision sensor calibration using parallel straight lines features

Line structured light vision sensor (LSLVS) calibration is to establish the relation between the camera and the light plane projector. This paper proposes a geometrical calibration method for LSLVS via three parallel straight lines on a 2D target. The approach is based on the properties of vanishing points and lines. During the calibration, one important aspect is to determine the normal vector of the light plane, another critical step is to obtain the distance parameter d of the light plane. In this paper, we put the emphasis on the later one. The distance constraint of parallel straight lines is used to compute a 3D feature point on the light plane, resulting in the acquisition of the parameter d. Thus, the equation of the light plane in the camera coordinate frame (CCF) can be solved out. To evaluate the performance of the algorithm, possible factors affecting the calibration accuracy are taken into account. Furthermore, mathematical formulations for error propagation are derived. Both computer simulations and real experiments have been carried out to validate our method, and the RMS error of the real calibration reaches 0.134 mm within the field of view 500 mm × 500 mm.     

二值时空编码照明三维测量中的冗余编码方法

在采用二值时空编码结构照明的三维测量中,由于遮挡、阴影及光学系统的低通滤波特性等原因导致被测物体部分区域解码错误或无法解码.为减轻这些因素对测量结果的影响,提出了一种采用冗余编码的二值时空编码照明三维测量方法.该方法在空间相邻区域设置相同编码,以时间坐标进行区别.解码时,根据编码的冗余性对结果进行校验、残缺编码恢复.与原有编码相比,在不增加投影模式数量的情况下,获得了更多的有效点数,提高了解码的可靠性,并为进一步的纠错提供了更多信息.     

Parallel splitting augmented Lagrangian methods for monotone structured variational inequalities

The typical structured variational inequalities can be interpreted as a system of equilibrium problems with a leader and two cooperative followers. Assume that, based on the instruction given by the leader, each follower can solve the individual equilibrium sub-problems in his own way. The responsibility of the leader is to give a more reasonable instruction for the next iteration loop based on the feedback information from the followers. This consideration leads us to present a parallel splitting augmented Lagrangian method (abbreviated to PSALM). The proposed method can be extended to solve the system of equilibrium problems with three separable operators. Finally, it is explained why we cannot use the same technique to develop similar methods for problems with more than three separable operators.