(p,q)型权投射线的凝聚层范畴上的倾斜丛

考察(p,q)型权投射线的凝聚层范畴上的倾斜丛,证明了其上的canonical倾斜丛总是构成一个slice,进而详细刻画了(p,q)型权投射线的向量丛子范畴的结构;进一步从不可分解对象,slice,level,domain等方面,阐述向量丛之间的一些重要性质,完全分类了所有的倾斜丛,即倾斜丛与向量丛范畴的slice一一对应.

激光投线定位法在电缆桥架施工中的应用

在变电站施工中,电缆桥架安装工作是一项非常重要的环节,通常主控楼、电气室电缆夹层都需要大量安装电缆桥架,而电缆桥架安装施工周期很长,其进度对整个工程工期影响非常大。桥架安装通常采用吊锤、棉线测定立柱和托臂位置,耗时耗力,经过一系列变电工程的建设实践,我安装队创新使用激光投线仪投射定位线的定位方法代替人工定位,使得立柱安装、托臂安装、调整过程效率得以提高。经过从化、东坡、富华等多个变电站工程实践,证明该方法既能满足施工和测量精度,又提高了施工效率。

基于最小二乘法拟合平面的激光平面度检测

为了实现激光投射线平面度的在线检测,提出一种基于最小二乘法拟合平面的激光平面度检测方法。首先运用平行光管搭配CCD工业相机采集不同方向上的激光投射线图像,并使用骨架提取、中值滤波等图像处理方法,将得到的激光线有效像素点转化为三维点云坐标。然后使用最小二乘法拟合测量的激光线水平面的平面度,提出平面度的计算方法,并且模拟激光线偏差角度为的水平面的平面度作为检测标准。实验验证本算法的一致性与准确度,该方法的提出增加了当前行业内激光头质量检测的标准,同时对比传统激光头质量检测,提高了检测准确性,减少了操作难度,在耗时上也减少了75%。作为一种高效可靠的检测手段,该方法在激光头生产与激光投线仪组装领域具有广泛的应用前景和参考价值。

Ray path of head waves with irregular interfaces

Head waves are usually considered to be the refracted waves propagating along flat interfaces with an underlying higher velocity.However,the path that the rays travel along in media with irregular interfaces is not clear.Here we study the problem by simulation using a new approach of the spectral-element method with some overlapped elements（SEMO） that can accurately evaluate waves traveling along an irregular interface.Consequently,the head waves are separated from interface waves by a time window.Thus,their energy and arrival time changes can be analyzed independently.These analyses demonstrate that,contrary to the case for head waves propagating along a flat interface,there are two mechanisms for head waves traveling along an irregular interface：a refraction mechanism and transmission mechanism.That is,the head waves may be refracted waves propagating along the interface or transmitted waves induced by the waves propagating in the higher-velocity media.Such knowledge will be helpful in constructing a more accurate inversion method,such as head wave travel-time tomography,and in obtaining a more accurate model of subsurface structure which is very important for understanding the formation mechanism of some special areas,such as the Tibetan Plateau.

SPEEDING-UP RE-SAMPLED ALGORITHM IN RAY CASTING VOLUME RENDERING OF MEDICAL IMAGES

Ray casting algorithm can obtain a better quality image in volume rendering, however, it exists some problems, such as powerful computing capacity and slow rendering speed. How to improve the re-sampled speed is a key to speed up the ray casting algorithm. An algorithm is introduced to reduce matrix computation by matrix transformation characteristics of re-sampling points in a two coordinate system. The projection of 3-D datasets on image plane is adopted to reduce the number of rays. Utilizing boundary box technique avoids the sampling in empty voxel. By extending the Bresenham algorithm to three dimensions, each re-sampling point is calculated. Experimental results show that a two to three-fold improvement in rendering speed using the optimized algorithm, and the similar image quality to traditional algorithm can be achieved. The optimized algorithm can produce the required quality images, thus reducing the total operations and speeding up the volume rendering.

Projection registration of X-ray image and CT image

A methodology for alignment of an X-ray image and a CT image, based on the Chamfer 3-4 distance transform and simulated annealing optimization algorithm is presented. Firstly, an initial transformation matrix is constructed. For the convenience of computing, geometric models of the X-ray device to reconstruct the calibration matrix are used. Then, by defining the distance between the 3-D protective and the 2-D object image, we optimize this distance matching problem, using the simulated annealing algorithm. This method is also integrated into medical intra-operation, dealing with the data set acquired from 3-D image workstation and active navigation.

多种X线投射位结合导管射频消融治疗房室结内折返性心动过速

目的 总结多种X线投射位结合导管射频消融治疗房室结内折返性心动过速（AVNRT）的效果及对并发症的预防.方法 206例AVNRT患者分别于后前位（PA）、右前斜30°（RAO 30°）和左前斜45°（LAO45°）X线投射位下,测量希氏束（His）至冠状窦（CS）口连线距离,选择距离最大投射位开始标测确定靶点,放电前再次于另外两种X线投射位下确认消融电极与His的距离.结果 于PA、RAO 30°和LAO 45°X线投射位下显示最大His至CS口连线距离的病例数分别为66、75、65例（P＞0.05）,距离分别为（2.94±0.87）、（2.98±0.76）和（2.91±0.52）cm（P＞0.05）.经三种不同X线投射位确认,靶点均位于His至CS口连线中点水平以上患者22例,其余患者184例,两者于放电过程中出现一过性第一度或第二度房室传导阻滞例数分别为4例和1例,差异有统计学意义（P＜0.01）.所有患者射频消融治疗均获得成功,未发生永久性房室传导阻滞.结论 采用多种X线投射位相结合的方法,并且熟练掌握不同X线投射位下的消融电极操作特点,有助于提高导管射频消融治疗AVNRT的手术成功率和预防消融并发症.

Calibration method for multi-line structured light vision sensor based on Plücker line

For the rapid calibration of multi-line structured light system,a method based on Plücker line was proposed.Most of the conventional line-structured light calibration methods extract the feature points and transform the coordinates of points to obtain the plane equation.However,a large number of points lead to complicated operation which is not suitable for the application scenarios of multi-line structured light.To solve this issue,a new calibration method was proposed that applied the form of Plücker matrix throughout the whole calibration process,instead of using the point characteristics directly.The advantage of this method is that the light plane equation can be obtained quickly and accurately in the camera coordinate frame.Correspondingly a planar target particularly for calibrating multi-line structured light was also designed.The regular lines were transformed into Plücker lines by extending the two-dimensional image plane and defining a new image space.To transform the coordinate frame of Plücker lines,the perspective projection mathematical model was re-expressed based on the Plücker matrix.According to the properties of the line and plane in the Plücker space,a linear matrix equation was efficiently constructed by combining the Plücker matrices of several coplanar lines so that the line-structured light plane equation could be furtherly solved.The experiments performed validate the proposed method and demonstrate the significant improvement in the calibration accuracy,when the test distance is 1.8 m,the root mean square(RMS)error of the three-dimensional point is within 0.08 mm.

GPU Accelerated Marine Data Visualization Method

The study of marine data visualization is of great value. Marine data, due to its large scale, random variation and multiresolution in nature, are hard to be visualized and analyzed. Nowadays, constructing an ocean model and visualizing model results have become some of the most important research topics of ‘Digital Ocean'. In this paper, a spherical ray casting method is developed to improve the traditional ray-casting algorithm and to make efficient use of GPUs. Aiming at the ocean current data, a 3D view-dependent line integral convolution method is used, in which the spatial frequency is adapted according to the distance from a camera. The study is based on a 3D virtual reality and visualization engine, namely the VV-Ocean. Some interactive operations are also provided to highlight the interesting structures and the characteristics of volumetric data. Finally, the marine data gathered in the East China Sea are displayed and analyzed. The results show that the method meets the requirements of real-time and interactive rendering.

Application of Extended Projective Riccati Equation Method to(2+1)-Dimensional Broer-Kaup-Kupershmidt System

In this paper, extended projective Riccati equation method is presented for constructing more new exact solutions of nonlinear differential equations in mathematical physics, which is direct and more powerful than projective Riccati equation method. In order to illustrate the effect of the method, Broer Kaup Kupershmidt system is employed and Jacobi doubly periodic solutions are obtained. This algorithm can also be applied to other nonlinear differential equations.

A SPARSE PROJECTION CLUSTERING ALGORITHM

A clustering algorithm based on Sparse Projection (SP), called Sparse Projection Clus- tering (SPC), is proposed in this letter. The basic idea is applying SP to project the observed data onto a high-dimensional sparse space, which is a nonlinear mapping with an explicit form and the K-means clustering algorithm can be therefore used to explore the inherent data patterns in the new space. The proposed algorithm is applied to cluster a complete artificial dataset and an incomplete real dataset. In comparison with the kernel K-means clustering algorithm, the proposed algorithm is more efficient.

Teaching method for reading views by analyzing lines and planes

This paper deals with the teaching method in reading engineering drawing. It introduces the basic theory and fundamental ideas as well as the approach of reading views by analyzing lines and planes. It gives out the steps for completing the third view based on the other two views. As it is easy and quick for students to read and understand views by this method, it is welcome by students in teaching practice.

Fast forward modeling of muon transmission tomography based on model voxelization ray energy loss projection

To solve the problems associated with low resolution and high computational effort infinite time,this paper proposes a fast forward modeling method for muon energy loss transmission tomography based on a model voxelization energy loss projection algorithm.First,the energy loss equation for muon transmission tomography is derived from the Bethe–Bloch formula,and the imaging region is then dissected into several units using the model voxelization method.Thereafter,the three-dimensional(3-D)imaging model is discretized into parallel and equally spaced two-dimensional(2-D)slices using the model layering method to realize a dimensional reduction of the 3-D volume data and accelerate the forward calculation speed.Subsequently,the muon energy loss transmission tomography equation is discretized using the ray energy loss projection method to establish a set of energy loss equations for the muon penetration voxel model.Finally,the muon energy loss values at the outgoing point are obtained by solving the projection coefficient matrix of the ray length-weighted model,achieving a significant reduction in the number of muons and improving the computational efficiency.A comparison of our results with the simulation results based on the Monte Carlo method verifies the accuracy and effectiveness of the algorithm proposed in this paper.The metallic mineral identification tests show that the proposed algorithm can quickly identify high-density metallic minerals.The muon energy loss response can accurately identify the boundary of the anomalies and their spatial distribution characteristics.

关于空间作图的一个定理

在立体几何教程中研究的空间作图有两类。一类是“想象的”(或约定的);一类是绘象的(投影图)。 在“想象的”作图中,引进约定:1)如果给定了确定平面的元素,这个平面就是可作的;2)在任何平面内,可以进行在平面几何已证实过的全部作图。根据约定,对于作图命题:“已知直线l及线外一点P,求作过点P与直线l相交垂直的直线”,作法是:a)直线l与点P决定平面a;b)在平面。内作所求作的直线。可以看出,约定类的作图,实质上只是理论上明确了求作对象的位置,整个过程中涉及到的空间图形存在于“想象”之中。随伴的附图,仅仅是为了帮助思考与叙述,并不是“真正”的作图。

SOME CONTRACTIONS OF THREEFOLD ALGEBRAIC FAMILY

The objects in this paper are all projective 3-folds over an algebresically closed field of characteristic 0. After simply generalizing the Rationality theorem, a kind of contractions. of non-minimal 3-folds is given