An artificial intelligent algorithm for tumor detection in screening mammogram

Cancerous tumor mass is one of the major types of breast cancer. When cancerous masses are embedded in and camouflaged by varying densities of parenchymal tissue structures, they are very difficult to be visually detected on mammograms. This paper presents an algorithm that combines several artificial intelligent techniques with the discrete wavelet transform (DWT) for detection of masses in mammograms. The AI techniques include fractal dimension analysis, multiresolution markov random field, dogs-and-rabbits algorithm, and others. The fractal dimension analysis serves as a preprocessor to determine the approximate locations of the regions suspicious for cancer in the mammogram. The dogs-and-rabbits clustering algorithm is used to initiate the segmentation at the LL subband of a three-level DWT decomposition of the mammogram. A tree-type classification strategy is applied at the end to determine whether a given region is suspicious for cancer. We have verified the algorithm with 322 mammograms in the Mammographic Image Analysis Society Database. The verification results show that the proposed algorithm has a sensitivity of 97.3% and the number of false positive per image is 3.92.     

针对静态感知系统的坐标系改进设计

由于四个菲涅尔透镜和四个热释电传感器组成的四元十字阵列静态感知系统探测视场角度大,相邻感知区域有重叠,导致传统的感知系统坐标系的探测精度降低。为了提高探测目标的可靠性,提出一种改进的二维坐标系。该坐标系根据相邻感知区域的重叠区,重新建立十字坐标系统。文中建立了新坐标系的理论模型,经过实验验证,该改进坐标系设计切实可行,使感知系统探测目标精度有所提高,具有一定的实际应用价值。     

采用自抗扰控制的三电机同步协调系统

自抗扰控制器自问世以来被用于多种应用场合,但其有着参数多,难整定的弊端,文中依据RBF神经网络结构简单、逼近能力强的优势提出了基于RBF神经网络的复合自抗扰参数调节器,利用RBF神经网络获得自抗扰参数的在线调整信息,且将其应用于三电机同步系统,经过实验验证,该调节器能实时调节自抗扰参数且能改善控制性能,具有实用性。     

红外立靶坐标测量系统的实现

提出了一种新型的红外立靶坐标测量系统的构想,借以改善目前靶场可见光立靶坐标测量系统工作受环境影响严重,不能全天时工作的缺点.对红外立靶坐标测量系统的关键技术问题红外探测器的波段选择进行了讨论,通过理论分析和试验验证,指出3-5μm的中波红外应作为红外立靶坐标测量系统的首选.在此基础上设计了一种可用于工程实践的红外立靶坐标测量系统,并对该系统的测量精度进行分析.     

激光雷达坐标测量系统的测角误差分析

为了精确地设计激光雷达坐标测量系统仪器,在研究激光雷达坐标测量系统测量原理和结构的基础上,建立了引入两轴垂直度误差、反射镜倾斜误差和反射镜入射激光束倾斜误差这3项主要系统误差的测角误差模型。由理论分析可知,在距离10m处,这3项系统误差各自引入的单点坐标测量误差最大值分别为124.1m,447.9m和242.4m。结果表明,在激光雷达坐标测量系统设计中,为保证在大空间测量中仍有很高测量精度,必须严格控制两轴垂直度误差、反射镜倾斜误差和反射镜入射激光束倾斜误差,并根据建立的误差模型进行参量标定和误差补偿。     

Detection of spicules on mammogram based on skeleton analysis

Existence of spicules is one of important clues of malignant tumors. This paper presents a new image processing method for the detection of spicules on mammogram. Spicules can be recognized as line patterns radiating from the center of tumor. To detect such characteristic patterns, line skeletons and a modified Hough transform are proposed. Line skeleton processing is effective in enhancing spinal axes of spicules and in reducing the other skeletons. The modified Hough transform is applied to line skeletons and radiating line structures are obtained. Experiments were made to test the performance of the proposed method. The system was designed using 19 training images, for which one normal case was recognized to be star-shaped. The other case were recognized correctly. Another experiments using 34 test images were also performed. The correct classification rate was 74%. These results shows the effectiveness of the proposed method.     

基于坐标变换的OFDM均衡方法

介绍了应用于正交频分复用(OFDM)系统中的一种基于坐标变换的信道均衡方法。该方法利用块导频进行信道估计,通过坐标旋转数字计算方法(CORDIC)进行坐标变换,并通过线性插值的方法跟踪补偿信道的时变衰落,从而提高系统的信道适应性;同时由于CORDIC将频域的数据线性化,有效降低了传统信道均衡方法的复杂度,便于硬件实现。仿真结果验证了该方法的有效性和适应性。     

An object oriented model scheduling for media-SoC

This paper proposes an object oriented model scheduling for parallel computing in media MultiProcessors System on Chip (MPSoC). Firstly, the Coarse Grain Data Flow Graph (CGDFG) parallel programming model is used in this approach. Secondly, this approach has the feature of unified abstraction for software objects implementing in processor and hardware objects implementing in ASICs, easy for mapping CGDFG programming on MPSoC. This approach cuts down the kernel overhead and reduces the code size effectively. The principle of the oriented object model, the method of scheduling, and how to map a parallel programming through CGDFG to the MPSoC are analyzed in this approach. This approach also compares the code size and execution cycles with conventional control flow scheduling, and presents respective management overhead for one application in media-SoC.     

A CAD system for the automatic detection of clustered microcalcifications in digitized mammogram films

Clusters of microcalcifications in mammograms are an important early sign of breast cancer. This paper presents a computer-aided diagnosis (CAD) system for the automatic detection of clustered microcalcifications in digitized mammograms. The proposed system consists of two main steps. First, potential microcalcification pixels in the mammograms are segmented out by using mixed features consisting of wavelet features and gray level statistical features, and labeled into potential individual microcalcification objects by their spatial connectivity. Second, individual microcalcifications are detected by using a set of 31 features extracted from the potential individual microcalcification objects. The discriminatory power of these features is analyzed using general regression neural networks via sequential forward and sequential backward selection methods. The classifiers used in these two steps are both multilayer feedforward neural networks. The method is applied to a database of 40 mammograms (Nijmegen database) containing 105 clusters of microcalcifications. A free-response operating characteristics (FROC) curve is used to evaluate the performance. Results show that the proposed system gives quite satisfactory detection performance. In particular, a 90% mean true positive detection rate is achieved at the cost of 0.5 false positive per image when mixed features are used in the first step and 15 features selected by the sequential backward selection method are used in the second step. However, we must be cautious when interpreting the results, since the 20 training samples are also used in the testing step.     

A new validation method for X-ray mammogram registration algorithms using a projection model of breast X-ray compression

Establishing spatial correspondence between features visible in X-ray mammograms obtained at different times has great potential to aid assessment and quantitation of change in the breast indicative of malignancy. The literature contains numerous nonrigid registration algorithms developed for this purpose, but existing approaches are flawed by the assumption of inappropriate 2-D transformation models and quantitative estimation of registration accuracy is limited. In this paper, we describe a novel validation method which simulates plausible mammographic compressions of the breast using a magnetic resonance imaging (MRI) derived finite element model. By projecting the resulting known 3-D displacements into 2-D and generating pseudo-mammograms from these same compressed magnetic resonance (MR) volumes, we can generate convincing images with known 2-D displacements with which to validate a registration algorithm. We illustrate this approach by computing the accuracy for two conventional nonrigid 2-D registration algorithms applied to mammographic test images generated from three patient MR datasets. We show that the accuracy of these algorithms is close to the best achievable using a 2-D one-to-one correspondence model but that new algorithms incorporating more representative transformation models are required to achieve sufficiently accurate registrations for this application.     

A comparison of methods for mammogram registration

Mammogram registration is an important technique to optimize the display of cases on a digital viewing station, and to find corresponding regions in temporal pairs of mammograms for computer-aided diagnosis algorithms. Four methods for mammogram registration were tested and results were compared. The performance of all registration methods was measured by comparing the distance between annotations of abnormalities in the previous and current view before and after registration. Registration by mutual information outperformed alignment based on nipple location, alignment based on center of mass of breast tissue, and warping.     

Qos和NP模型化的一种面向对象方法

本文目的在于用ＯＯＰ方法描述ＱｏＳ和ＮＰ的模型，和其在层次状叠放的不同网络中的表示     

光学坐标测量系统中的关键技术

光学坐标测量系统是建立在数字近景摄影测量技术基础上的一种新型精密测量系统,具有便携性好、精度高、测量范围大、受环境干扰小等优点,适合工业工程的现场测量。针对工业现场精密测量的需求,对摄像机模型进行了分析,提出了摄像机残差修正问题,给出了修正方法及基于双目立体视觉原理的通用坐标测量数学模型。搭建了完整的光学坐标测量系统,测量精度优于±0.1 mm/m。     

Multi-view coordinate system transformation based on robot

The registration of point cloud is important for large object measurement. A measurement method for coordinate system transformation based on robot is proposed in this paper. Firstly, for obtaining extrinsic parameters, the robot moves to three different positions to capture the images of three targets. Then the transformation matrix X between camera and tool center point (TCP) coordinate systems can be calculated by using the known parameters of robot and the extrinsic parameters, and finally the multi-view coordinate system can be transformed into robot coordinate system by the transformation matrix X. With the help of robot, the multi-view point cloud can be easily transformed into a unified coordinate system. By using robot, the measurement doesn’t need any mark. Experimental results show that the method is effective.     

一种相控阵体制的抗干扰分析方法

从信干比角度考虑,传统的全向辐射体制系统很难实现远距离抗干扰通信,而相控阵体制的高增益、低旁瓣特征可以使系统获得一定的抗干扰能力。从信干比分析入手,引入干扰概率指标,给出了一种针对抗干扰能力的统计分析方法,并进行了仿真分析,结果表明,由于阵面规模直接决定了方向图特性,而天线阵的体积、重量、功耗、成本均随阵元数目的增多而增长,所以在总体设计时需要对阵面规模进行折中考虑。该方法已成功应用于系统硬件总体设计。     

A registration framework for the comparison of mammogram sequences

In this paper, we present a two-stage algorithm for mammogram registration, the geometrical alignment of mammogram sequences. The rationale behind this paper stems from the intrinsic difficulties in comparing mammogram sequences. Mammogram comparison is a valuable tool in national breast screening programs as well as in frequent monitoring and hormone replacement therapy (HRT). The method presented in this paper aims to improve mammogram comparison by estimating the underlying geometric transformation for any mammogram sequence. It takes into consideration the various temporal changes that may occur between successive scans of the same woman and is designed to overcome the inconsistencies of mammogram image formation.     

GPON系统中面向业务的上行调度成帧算法

论证了传统成帧方式的弊端,然后在ITU-T G.984.3-200402-Ⅰ协议的基础上,提出了根据不同业务类型的优先级和等待时间调度的上行成帧算法,并且分析了算法的有效性,对算法进行了仿真,结果证明,改进型算法在负载较重的情况下,能够很好地保证高优先级数据优先成帧,同时也兼顾了低优先级数据,不至于堵塞.     

An application oriented test procedure for designing microsteppingstep motor controllers

Describes an application oriented set-up for determining current references for a microstepping step motor controller. This eliminates the need for calculating these references from motor characteristics. Motor nonlinearities and asymmetries are taken into consideration and references for controllers can be obtained by an unattended test for any microstep size desired     

The construction of an anatomically based model of the humanventricular conduction system

The ventricular conduction system is a complicated network of specialized muscle cells responsible for the transmission of electrical activity between the atria and the ventricles of the human heart. It has been the focus of numerous electrical and anatomical studies at both the microscopic and macroscopic levels. An understanding of its behavior at both levels is considered important, because it is primarily responsible for the spread of excitation in the ventricles. Previous computer models have been very simple ones that have been primarily adjuncts to models of the ventricles. This paper describes a strategy for the construction of conduction system models which is based on real microscopic and macroscopic features, although the model still is much simpler than reality. The model contains almost 35,000 individual cylindrical elements, each of whose physical dimensions approximate unit bundles of Purkinje and atrioventricular nodal cells. The model, whose physical appearance closely resembles that of the conduction system, was generated from limited anatomical data in less than 2 min CPU time on an IBM 3090 at the Cornell National Supercomputer Facility.     

A clinically oriented video-based system for quantification of eyelid movements

A field-worthy system was developed to quantify the eyelid movements in clinical sites. The system consists of a home-use charge-coupled device video camera, a processing unit, and a personal computer. A white marker of 4-mm diameter and 30-mg weight is attached to the lower margin of the upper eyelid. The processing unit automatically detects the vertical displacement of the upper edge of the marker. One marker is attached to each eye so that the movements of the both eyelids are measured with one camera simultaneously. The measurement error of the system was evaluated in experiments on eight healthy subjects and eight patients with eyelid paralysis. The mean of the absolute error of peak amplitudes occurring in 2 min was 0.81 mm, with the worst error being +1.7 mm. The reproducibility of the mean peak amplitude measured on five consecutive days was within 1 mm. The mean peak amplitudes of both eyes were measured preoperatively and postoperatively for approximately three months for three patients who were operated on to remove vestibular schwannoma. The results demonstrated basic clinical utility of the system.