Smooth closed surfaces with discrete triangular interpolants

Discrete interpolants which involve cross boundary derivatives in an attempt to form C¹ surfaces have the following major problem: Requiring C¹ joins between patches makes sense only if the patch domains are adjacent in the domain space. This makes it impossible to form C¹ closed surfaces, or indeed any surface which contains more connections than can be achieved in the domain.

This paper develops a method of forming smooth closed (or otherwise complexly connected) surfaces from a discrete triangular interpolant by relaxing the C¹ property of an interpolant to ‘Visually C¹”.

The only constraint on the scheme is that the data to be interpolated define a unique tangent plane at each vertex where several triangles meet. Then each patch can be calculated independently of its neighbors, using only data defined at its vertices, and the domain for each triangular patch can be chosen without regarding the connectivity of the patch with others. This last feature could be of great interest to a designer of a surface since one can choose the domain of each patch to be an equilateral triangle, and give it no further thought.     

Towards a practical method of user interface evaluation

This paper describes a practical method for evaluating the usability of human-computer interfaces. The paper specifies the requirements of such a method, and then outlines our work in developing a method to meet this specification. The method is based on the conduct of realistic tasks with an interactive system and the subsequent systematic elicitation of end-users' and designers' reactions to the interface using a criterion-based evaluation checklist.

Two practical examples are used to illustrate development of the method: (a) evaluation of a prototype production scheduling system, and (b) comparative assessment of the usability of three prototype user interfaces to a public-access database. The paper discusses some issues raised by the method and considers how it can be furthe developed.     

Optimal average cost manufacturing flow controllers: convexity anddifferentiability

The authors consider the control of a production facility consisting of a single workstation with multiple failure modes and part types using a continuous flow control model. Technical issues concerning the convexity and differentiability of the differential cost function are investigated. It is proven that under an optimal control policy the differential cost is C¹ on attractive control switching boundaries     

Hybrid plate vibration models for coarse-mesh analysis

Hybrid FE combined membrane + bending rectangular plate vibration models (7 + 11)βC⁰ and (7 + 17)βC¹ are proposed for computer assisted identification of vibration modes for high degree efficient coarse-mesh analysis. Accurate yet cost effective hierarchial FE matrix generation capability is provided through the expedient of an exact analytical integration algorithm, which circumvents many time consuming steps and associated controversies of the numerical quadrature interactions, while yielding computational economy comparable to that required by the single-point Gaussian rule. Samples of numerical experiments corroborate the present development and confirm the high accuracy with rapid convergence characteristics.     

Electronic `how things work' articles: two early prototypes

The electronic encyclopedia exploratorium (E³) is a vision of a future computer system-an electronic book describing how thing work. Typical articles in E³ will describe such mechanisms as compression refrigerators, engines, telescopes, and mechanical linkages. Each article will provide simulations, three-dimensional animated graphics that the user can manipulate, laboratory areas that allow a user to modify the device or experiment with related artifacts, and a facility for asking questions and receiving customized, computer-generated English-language explanations. Some of the foundational technology is discussed, focusing on topics in artificial intelligence, graphics, and user interfaces. The initial prototype system and the technical lessons learned from it, as well as the second prototype currently under construction, are described     

Sea Ice Classification of Polarimetric SAR Imagery based on Decision Tree Algorithm of Attributes’ Subtraction

Polarimetric SAR image usually has multiple polarization attributes,and the imaging brightness of different sea ice types in different polarization modes is obviously different.A decision tree (SDDT) analysis method on attributes’ subtractions suited for sea ice classification of polarimetric SAR imagery is proposed in this paper.The subtractions between any two attributes based on a given n attributes are calculated.Then their classification ability and optimal divided threshold are calculated.The most effective attribute is discovered and used to construct classification tree.According to this strategy,it equal to find the optimal subtraction attributefrom n+C ² n features for classification,which include original n attributes and C²n subtraction attributes.In addition,we use GainRatio to compare the classification ability between different attributes firstly.When there are several attributes with a same GainRatio,we consider the width of the split point (ΔWidth) and the total width of the attribute (TotalWidth) and define a classification ability index ClassifyAbility=GainRatio* ΔWidth/TotalWidth.By calculating and comparing ClassifyAbility index,an optimal attribute with the largest attribute classification abilitycan be selected.Experiments show that the accuracy of SDDT algorithmhas ten percent higher than that of C4.5 algorithm using a same training samples.     

Reconfigurable and transportable container-integrated production system

In this paper, the concept and the prototype realization of a novel reconfigurable small-footprint manufacturing system in a transportable container is presented. The containerized format enables transportation of the system to provide on-site manufacturing, enabling the benefits of localized service delivery without duplication of equipment at multiple locations.Three industrial product use cases with varying manufacturing and performance requirements were analysed. All of the use cases demanded highly customized products with high quality in low production volumes. Based on their requirements, a general system specification was derived and used to develop a concept for the container-integrated factory.A reconfigurable, modular manufacturing system is integral to the overall container concept. Production equipment was integrated in the form of interchangeable process modules, which can be quickly connected by standard utility supply and control interfaces. A modular and self-configuring control system provides assisted production workflow programming, while a modular process chain combining Additive Manufacturing, CNC milling, precision assembly and cleaning processes has been developed.A prototype of the container-integrated factory with reconfigurable process modules and control system has been established, with full functionality and feasibility of the system demonstrated.     

T-Bézier曲线能量法的光顺计算

针对T-Bézier曲线的光顺要求,提出了用能量法对T-Bézier曲线进行光顺。首先通过能量法对T-Bézier曲线修改一个控制顶点使之达到光顺,同时给出了扰动因子α对曲线的影响,由此得到欲移动T-Bézier曲线的一个控制顶点达到光顺,可先确定α,再确定新的控制顶点,就可得到光顺后的新的T-Bézier曲线。对整条曲线进行光顺时先确定扰动因子{α_i}_i=1ⁿ,然后求解一个系数矩阵为实对称三对角矩阵的方程组,再依次确定新的控制点列{P_i}_i=0ⁿ,最后由控制顶点确定光顺后的三次T-Bézier插值曲线,从而使T-Bézier曲线不仅达到整体光顺而且在数据点实现C²连续。最后,给出了3个实例,说明该算法是简单、实用和有效的。     

Towards Defense Against Adversarial Attacks on Graph Neural Networks via Calibrated Co-Training

Graph neural networks (GNNs) have achieved significant success in graph representation learning. Nevertheless, the recent work indicates that current GNNs are vulnerable to adversarial perturbations, in particular structural perturbations. This, therefore, narrows the application of GNN models in real-world scenarios. Such vulnerability can be attributed to the model’s excessive reliance on incomplete data views (e.g., graph convolutional networks (GCNs) heavily rely on graph structures to make predictions). By integrating the information from multiple perspectives, this problem can be effectively addressed, and typical views of graphs include the node feature view and the graph structure view. In this paper, we proposeC²oG, which combines these two typical views to train sub-models and fuses their knowledge through co-training. Due to the orthogonality of the views, sub-models in the feature view tend to be robust against the perturbations targeted at sub-models in the structure view.C²oGallows sub-models to correct one another mutually and thus enhance the robustness of their ensembles. In our evaluations,C²oGsignificantly improves the robustness of graph models against adversarial attacks without sacrificing their performance on clean datasets.     

2D Z-string: A new spatial knowledge representation for image databases

The knowledge structure called the 2D C⁺-string, proposed by Huang et al., to represent symbolic pictures allows a natural way to construct iconic indexes for images. According to the cutting mechanism of the 2D C⁺-string, an object may be partitioned into several subparts. The number of partitioned subparts is bounded to O(n²), where n is the number of objects in the image. Hence, the string length is also bounded to O(n²). In this paper, we propose a new spatial knowledge representation called the 2D Z-string. Since there are no cuttings between objects in the 2D Z-string, the integrity of objects is preserved and the string length is bounded to O(n). Finally, some experiments are conducted to compare the performance of both approaches.     

面向服务的网格资源管理模型研究

开放网格服务体系结构（OGSA）的出现表明让网格资源以服务形式提供标准化的接口已成为趋势,以前的资源管理模式已经不能满足应用的要求。为此,提出了一种面向服务的作业管理机制,它为用户提供透明的、与资源物理位置无关的并带有会话支持的作业服务接口,还引入了服务分级的概念来表示用户需求的不同网格服务级别,作业管理系统则根据可定制的服务级别,将各项QoS特性映射到具体的作业管理行为。最后以电子政务为例,初步构建了该模型的原形系统。     

面向服务的网格资源管理模型研究*

开放网格服务体系结构(OGSA) 的出现表明让网格资源以服务形式提供标准化的接口已成为趋势,以前的资源管理模式已经不能满足应用的要求。为此,提出了一种面向服务的作业管理机制,它为用户提供透明的、与资源物理位置无关的并带有会话支持的作业服务接口,还引入了服务分级的概念来表示用户需求的不同网格服务级别,作业管理系统则根据可定制的服务级别,将各项QoS 特性映射到具体的作业管理行为。最后以电子政务为例,初步构建了该模型的原形系统。     

Quartic discriminants and tensor invariants

Discusses the calculation of discriminants of polynomials. The discriminant is a function of the coefficients that indicates if the polynomial has any double roots. The discriminant Δ₄ of a homogeneous quartic f(x,w) = Ax⁴+4Bx³w+6Cx² w²+4Dxw³+Ew⁴ = 0 is Δ₄ = 27(I₃)²-(I₂)³, where I₂ = AE-4BD+3C² and I₃ = ACE-AD ²-B²E+2BCD-C³ (this is the Hilbert representation). The author shows how to write the discriminant as a tensor diagram. The discriminant of a polynomial is an example of an invariant quantity. Tensor diagrams are particularly useful to express invariant quantities. Adding a dimension moves us from the world of (1D) homogeneous polynomials to 2D homogeneous (2DH) geometry (curves in the projective plane). It is shown that a relationship exists between the possible root structures of a 4th-order polynomial and the possible degeneracies of a 3rd-order curve     

具有局部性质的球面插值样条曲线的构造

高维球面样条曲线拟合技术在计算机动画和惯性导航等领域都受到广泛地关注.实际中常需球面曲线插值给定的数据点,并要求曲线具有一定的连续性和良好的局部性质.此前的方法存在一定的局限性.为此,基于球面Bézier曲线,提出了一种仅利用插值点位置信息便可在任意维空间中构造C 2球面插值样条曲线的新方法.首先,通过映射拟合出了插值...     

Two algorithms for volume-preserving approximations of surfaces of revolution

The paper deals with volume-preserving approximations of surfaces of revolution. The approximating surfaces are generated only by line segments and circular arcs of a constant radius r. Further, for r > 0, the approximating surfaces are visually C¹ surfaces. For r = 0, developable C⁰ surfaces are obtained (consisting of either congruent cylinders or frustums of cones of revolution). Two algorithms are discussed. The first algorithm preserves the volume enclosed by a surface of revolution and the planes of every two latitude circles; the approximating surface is, however, no longer a surface of revolution. The second algorithm applies an approximating surface of revolution; however, the volume preservation no longer holds globally.     

An adaptive method for smooth surface approximation to scattered 3D points

The construction of a surface from arbitrarily scattered data is an important problem in many applications. When there are a large number of data points, the surface representations generated by interpolation methods may be inefficient in both storage and computational requirements. This paper describes an adaptive method for smooth surface approximation from scattered 3D points. The approximating surface is represented by a piecewise cubic triangular Bézier surface possessing C¹ continuity. The method begins with a rough surface interpolating only boundary points and, in the successive steps, refines it by adding the maximum error point at a time among the remaining internal points until the desired approximation accuracy is reached. Our method is simple in concept and efficient in computational time, yet realizes efficient data reduction. Some experimental results are given to show that surface representations constructed by our method are compact and faithful to the original data points.     

Investigating the affective quality of interactivity by motion feedback in mobile touchscreen user interfaces

Emotion is a key aspect of user experience. To design a user interface for positive emotional experience, the affective quality of the user interface needs to be carefully considered. A major factor of affective quality in today's user interface for digital media is interactivity, in which motion feedback plays a significant role as an element. This role of motion feedback is particularly evident in touchscreen user interfaces that have been adopted rapidly in mobile devices. This paper presents two empirical studies performed to increase our understanding of motion feedback in terms of affective quality in mobile touchscreen user interfaces. In the first study, the relationships between three general motion properties and a selected set of affective qualities are examined. The results of this study provide a guideline for the design of motion feedback in existing mobile touchscreen user interfaces. The second study explores a new dimension of interactivity that is the Weight factor of Laban's Effort system. To experiment the Weight factor in a mobile touchscreen user interface, a pressure sensitive prototype was developed to recognize the amount of force applied by the user's finger action. With this prototype, the effects of implementing pressure requirements on four different types of user interfaces were examined. Results show that implementing the Weight factor can significantly influence the affective quality and complement the physical feel of a user interface. The issues to consider for effective implementation are also discussed.     

Modelling form-based interfaces with bipartite state machines

This article presents the concept of form storyboarding, a new modelling method for eliciting, specifying and communicating functional requirements of applications with form-based interfaces. We identify two-staged interaction as the abstract concept behind form-based interfaces. The method encompasses a visual language for the documents to be created and a set of proposals for the activities involved in that. The method fits to different and ubiquitous types of submit/response style interfaces, i.e. mainframe terminals as well as web-based interfaces. The method yields an abstract interface model based on bipartite state machines. The model is executable and can be used for automatic prototype generation. Form storyboarding is first and foremost a feature-driven approach. The whole form storyboard can be obtained by collecting single system features. Crucial for this approach is the fact that diagrams can be combined in an easy operation, by building the union of both diagrams and identifying nodes and edges with the same name.