On improving physical selectivity in the treatment of cancer: A systems modelling and optimisation approach

This paper presents the results arising from a practical implementation of a novel hybrid optimisation scheme, used to solve the inverse problem in radiotherapy treatment planning (RTP). A matrix-based beam model which has been developed making use of a control systems modelling approach is used, together with a hybrid optimisation scheme. Patient-specific compensator profiles are deduced from the intensity modulated beam profiles obtained from the hybrid scheme, with use being made of an exponential attenuation factor coupled with a point spread convolution function to account for the scatter in the compensator. A good agreement between the predicted and actual conformational distributions is achieved.     

Embedded Implicit Stand-Ins for Animated Meshes: A Case of Hybrid Modelling

In this paper, we address shape modelling problems, encountered in computer animation and computer games development that are difficult to solve just using polygonal meshes. Our approach is based on a hybrid-modelling concept that combines polygonal meshes with implicit surfaces. A hybrid model consists of an animated polygonal mesh and an approximation of this mesh by a convolution surface stand-in that is embedded within it or is attached to it. The motions of both objects are synchronised using a rigging skeleton. We model the interaction between an animated mesh object and a viscoelastic substance, which is normally represented in an implicit form. Our approach is aimed at achieving verisimilitude rather than physically based simulation. The adhesive behaviour of the viscous object is modelled using geometric blending operations on the corresponding implicit surfaces. Another application of this approach is the creation of metamorphosing implicit surface parts that are attached to an animated mesh. A prototype implementation of the proposed approach and several examples of modelling and animation with near real-time preview times are presented.     

Multiplication and convolution of distributions for signal processing theory

In the theory of signal processing, signals are usually classified either by determining whether their time domain is discrete or continuous, or by determining whether they are periodic. However, no comprehensive definitions of multiplication and convolution exist that are consistent with the theories behind all classes, although some important theorems in signal processing involve multiplication and convolution. In order to unite the theories behind these classifications, we will consider tempered distributions. In this paper, we propose an approach to the multiplication and convolution of distributions that is appropriate to signal processing theory, and prove a well-known theorem regarding the impulse response of continuous linear time-invariant systems of tempered distributions in the context of this new approach.     

A graph theoretic approach to multivariable control system design

A graph theoretic approach is described for the design of multivariable control for large systems as an alternative to geometric methods. An example is given f⊙r a distillation column to demonstrate the technique, with a particular reference to aspects of disturbance rejection and the possibilities for pole assignment.     

Advanced point-mass method for nonlinear state estimation

State estimation of discrete-time nonlinear non-Gaussian stochastic systems by point-mass approach, which is based on discretization of state space by a regular grid and numerical solution of Bayesian recursive relations, is treated. The stress is laid to grid design which is crucial for estimator quality and significantly affects the computational demands of the estimator. Boundary-based grid design, thrifty convolution, and multigrid design with grid splitting and merging are proposed. The main advantages of these techniques are nonnegligible support delimitation, time-saving computation of convolution, and effective processing of multimodal probability density functions, respectively. The techniques are involved into the basic point-mass approach and a new general-purpose, more sophisticated point-mass algorithm is designed. Computational demands and estimation quality of the designed algorithm are presented and compared with the particle filter in a numerical example.     

Constructing subsurface profiles using GIS

A geographic information system (GIS) macro procedure for creating subsurface profiles from well log data is developed. The well log data base is constructed from interpretation of a series of borehole geophysical logs. The GIS procedure targets a modelling area and interpolates the well data base to create a three-dimentional representation of the subsurface environment. Any number of cross-sectional profiles or three-dimensional images of well log data may be created and viewed interactively. The resulting profiles provide basic geometric data for ground water flow and contaminant transport models. A brief introduction to the ARC/INFO system, emphasizing the attributes of the data structure and the macro language, is given. Several subsurface profiles of Shelby County, Tennessee are developed using the GIS profile procedure.     

基于快速尺度空间特征检测的手势识别方法

在基于几何模型的手势识别方法中,尺度空间特征检测是一种最常用的方法。由于传统方法涉及大量的高斯卷积运算,计算非常复杂。提出了一种快速的尺度空间特征检测方法,采用一组简单的矩形特征模板近似传统方法中复杂的高斯导数卷积模板,得到了尺度空间几何特征的快速检测子。通过对手势图像中Blob和Ridge结构的检测,得到手掌和手指结构的描述,进而完成手势识别。矩形特征模板的卷积可以用积分图进行快速计算,该方法使特征检测的速度得到了很大提高。在标准数据集和自然环境图像数据上的实验结果表明,该方法在保证识别准确率的同时,有效地提高了手势识别的实时性。     

基于改进单点多盒检测器的大坝缺陷目标检测方法

为提升大坝安全运维的效率,大坝缺陷目标检测模型有助于辅助巡检人员进行缺陷检测。大坝缺陷几何形状多变,而采用传统卷积方式进行特征提取的单点多盒检测器（SSD）模型无法适应缺陷的几何变换。针对上述问题,提出可变形卷积单步多框检测器（DFSSD）模型。首先将原始SSD的主干网络VGG16中的标准卷积替换为可变形卷积,用于处理缺陷的几何变换,并且通过学习卷积偏移量来提升模型的空间信息建模能力;其次针对不同特征的尺寸,改进先验框比例,从而提高模型对条形特征的检测精度与模型的泛化能力;最后为解决训练集正负样本不均衡的问题,采用改进的非极大值抑制（NMS）算法来优化学习效果。实验结果表明：DFSSD模型较基准模型SSD在大坝缺陷图像上的平均检测精度提升了5.98%。相较于基于区域的更快卷积神经网络（Faster R-CNN）和SSD模型,DFSSD模型在大坝缺陷目标检测精度提升上有较好的效果。     

An Iterative Algebraic Geometric Approach for Identification of Switched ARX Models with Noise

The algebraic geometric (AG) approach has been used to identify switched auto regressive exogenous (SARX) models in hybrid systems, and it has several advantages over other SARX identification methods. This paper is focused on improving the estimation accuracy of the AG approach for systems corrupted with indispensable noises. A stochastic hybrid decoupling polynomial (SHDP) is constructed by reformulating the hybrid decoupling polynomial (HDP) used in the original AG method. An iterative scheme is developed to estimate parameters of the SHDP, which are used to calculate the SARX model parameters. This estimation involves linear regression with multiplicative noises, therefore a novel approach is proposed to solve this regression problem. Then, the parameters are recovered from the SHDP. Finally, all these steps for SARX model identification are summarized in an algorithm called the iterative algebraic geometric (IAG) approach. Simulations and experimental validation results are shown to demonstrate the effectiveness of and the improvement made by the proposed IAG method.     

Fault detection and isolation in nonlinear systems

This paper deals with fault detection and identification in dynamic systems when the system dynamics can be modeled by smooth nonlinear differential equations including affine, bilinear or linear parameter varying (LPV) systems. Two basic approaches will be considered, these apply differential algebraic and differential geometric tools.In the differential algebraic approach the state elimination methods will be used to derive nonlinear parity relations. In the specific case when a reconstruction of the fault signal is needed the dynamic inversion based approach will be investigated. This approach will also be studied from geometric point of view. The geometric approach, as proposed by Isidori and De Persis, is suitable to extend the detection filter and unknown input observer design approaches (well elaborated for LTI systems) to affine nonlinear systems.Beyond the development of the theory of fault detection and identification it is equally important to offer computable methods and to analyze the robustness properties against uncertainties. Both the observer based and the inversion based approaches will be elaborated for LPV systems that may offer computational tools inherited from linear systems and also allow to design for robustness utilizing results from robust filtering and disturbance attenuation.     

Keyword clustering for user interest profiling refinement within paper recommender systems

To refine user interest profiling, this paper focuses on extending scientific subject ontology via keyword clustering and on improving the accuracy and effectiveness of recommendation of the electronic academic publications in online services. A clustering approach is proposed for domain keywords for the purpose of the subject ontology extension. Based on the keyword clusters, the construction of user interest profiles is presented on a rather fine granularity level. In the construction of user interest profiles, we apply two types of interest profiles: explicit profiles and implicit profiles. The explicit profiles are obtained by relating users’ interest-topic relevance factors to users’ interest measurements of these topics computed by a conventional ontology-based method, and the implicit profiles are acquired on the basis of the correlative relationships among the topic nodes in topic network graphs. Three experiments are conducted which reveal that the uses of the subject ontology extension approach as well as the two types of interest profiles satisfyingly contribute to an improvement in the accuracy of recommendation.     

基于卷积曲面的几何造型方法

卷积曲面是一种很有潜力的隐式曲面造型方法。由于卷积的可叠加性质,使得其生成的曲面很光滑,不会产生凸包和裂缝。卷积曲面造型是基于骨架的,其骨架可以是曲线或曲面,也可以以物体轮廓线为骨架原型来获取所需要的物体造型。在卷积造型的过程中,通过对骨架加权可以精细地控制结果曲面的形状。在介绍了卷积曲面造型的各类方法后,分析了其特点和发展方向。     

Computing the Minkowski sum of ruled surfaces

The boundary of the Minkowski sum of two geometric objects is part of the so-called convolution surface of the boundary surfaces of the two input objects. In most cases, convolution surfaces can be computed only by numerical algorithms. The present paper studies convolution surfaces of ruled surfaces. There, explicit parameterizations for the convolution surface can be derived. Moreover, we study the rational convolution surface of two rational ruled surfaces and the connection to rational parameterizations of offsets of rational ruled surfaces.     

结合Canny和距离变换的矩形模式特征提取方法

提出了一种图像矩形模式特征提取算法。首先利用Canny算子对图像纹理敏感特性求取图像的Canny边缘;对Canny边缘结果计算其距离变换图,可有效减小纹理复杂区域对后续矩形模式特征提取的影响;然后对距离变换图进行掩膜卷积,对其结果进行聚类,获得矩形模式特征的中心;最后利用几何约束求解出矩形模式特征的四个顶点。实验证明了该算法有效可行,特征定位精度在真实图像上可达1.3像素。     

Convolution surfaces based on polygons for infinite and compact support kernels

We provide formulae to create 3D smooth shapes fleshing out a skeleton made of line segments and planar polygons. The boundary of the shape is a level set of the convolution function obtained by integration along the skeleton. The convolution function for a complex skeleton is thus the sum of the convolution functions for the basic elements of the skeleton. Providing formulae for the convolution of a polygon is the main contribution of the present paper. We improve on previous results in several ways. First we do not require the prior triangulation of the polygon. Then, we obtain formulae for families of kernels, either with infinite or compact supports. Last, but not least, in the case of compact support kernels, the geometric computations needed are restricted to intersections of spheres with line segments.     

基于可变形卷积的多人人体姿态估计

目前针对人体姿态估计的深度神经网络都是在特征图的固定位置上进行采样,无法对人体姿态的几何变换进行建模,当人体实例在尺寸、姿势、拍摄角度等方面发生变化后,网络泛化能力较差.因此,文中提出基于可变形卷积的多人人体姿态估计方法.利用可变形卷积对目标几何变换建模能力较强的特性,设计特征提取模块,可在人体关键点几何变化的条件下保证检测的准确性.为了进一步提高网络性能,利用预训练残差网络.模型的预测值与二维高斯模型生成的真值用于计算损失,并迭代训练模型,能在拍摄视角、附着物及人物尺度变化等复杂条件下有效检测人体关键点.实验表明,文中模型可有效提升人体关键点检测的准确性.     

Discontinuous Double-shell Domes through Islamic eras in the Middle East and Central Asia: History, Morphology, Typologies, Geometry, and Construction

This paper presents a developed geometric approach for deriving the typologies and geometries of discontinuous double-shell domes in Islamic architecture. Common geometric attributes are created using a corpus of twenty one domes that were built in the Middle East and Central Asia, beginning from the early through to the late Islamic periods. An outline of the origin and development of the discontinuous double-shell domes and their morphological features are addressed. Using the al-Kashi geometrical essences, a four-centered profile as an initial shape is constructed based on new geometric parameters to deduce the geometric commonalities of the two aspects of formal language (typologies and geometries) of such domes. Common geometric prototypes for typical profiles shared by the study cases are generated and formulated according to a proposed system. The theoretical frame work for the formal language of discontinuous double-shell dome architecture is structured to indicate a moderate development of this sort of Islamic domes and highlight the specific geometric relationship between the Islamic domical configurations and practical mathematic rules for many decades. It can also be established a basic approach for considering the geometric compositional designs and the typological derivations of the other eastern domes.