通用几何约束系统统一建模研究

在几何约束和几何实体的基本约束和欧拉参数表达的基础上,研究了通用几何约束系统的统一建模问题。通过对三维几何实体姿态约束和位置约束解耦性的分析,抽象出球实体、盒体和球盒体三种基本几何实体表达空间几何实体,并以基本约束的组合表达几何约束,形成几何约束模型特有的层次结构;并以有向图管理几何约束系统,可以清晰地反映姿态约束和位置约束的解耦性,实现约束系统的细粒度分解,得到规模更小的求解序列,实现高效求解。方法实现于原型系统WhutVAS中。     

Modelling the impacts of crowds on occupants in the built environment—A static,rule-based approach to human perception and movement

A building occupant’s experiences are not passive responses to environmental stimuli, but are the results of multifaceted, prolonged interactions between people and space. We present a framework and prototype software tool for logically reasoning about occupant perception and behaviour in the context of dynamic aspects of buildings in operation, based on qualitative deductive rules. In particular, we focus on the co-presence of different user groups and the resulting impact on perceptual and functional affordances of spatial layouts by utilising the concept of spatial artefacts. As a first proof of concept of our approach, we have implemented a prototype crowd analysis software tool in our new system ASP4BIM, developed specifically to support architectural design reasoning in the context of public-facing buildings with complex signage systems and diverse intended user groups. We evaluate our prototype on the Urban Sciences Building at Newcastle University, a large, state-of-the-art living laboratory and multipurpose academic building. Our findings are that the ASP4BIM-based prototype supports a range of novel query services for formally analysing the impacts of crowds on pedestrians that are logically derived through the use of qualitative deductive rules, that complements other powerful crowd analysis approaches such as agent-based simulation.     

Exact solution for the optimal neuronal layout problem

Evolution perfected brain design by maximizing its functionality while minimizing costs associated with building and maintaining it. Assumption that brain functionality is specified by neuronal connectivity, implemented by costly biological wiring, leads to the following optimal design problem. For a given neuronal connectivity, find a spatial layout of neurons that minimizes the wiring cost. Unfortunately, this problem is difficult to solve because the number of possible layouts is often astronomically large. We argue that the wiring cost may scale as wire length squared, reducing the optimal layout problem to a constrained minimization of a quadratic form. For biologically plausible constraints, this problem has exact analytical solutions, which give reasonable approximations to actual layouts in the brain. These solutions make the inverse problem of inferring neuronal connectivity from neuronal layout more tractable.     

Data model for extensible support of explicit relationships in design databases

We describe the conceptual model of SORAC, a data modeling system developed at the University of Rhode Island. SORAC supports both semantic objects and relationships, and provides a tool for modeling databases needed for complex design domains. SORAC's set of built-in semantic relationships permits the schema designer to specify enforcement rules that maintain constraints on the object and relationship types. SORAC then automatically generates C++ code to maintain the specified enforcement rules, producing a schema that is compatible with Ontos. This facilitates the task of the schema designer, who no longer has to ensure that all methods on object classes correctly maintain necessary constraints. In addition, explicit specification of enforcement rules permits automated analysis of enforcement propagations. We compare the interpretations of relationships within the semantic and object-oriented models as an introduction to the mixed model that SORAC supports. Next, the set of built-in SORAC relationship types is presented in terms of the enforcement rules permitted on each relationship type. We then use the modeling requirements of an architectural design support system, called Arch Objects, to demonstrate the capabilities of SORAC. The implementation of the current SORAC prototype is also briefly discussed.     

Quasidynamic layout optimizations for improving data locality

Compiler-directed locality optimization techniques are effective in reducing the number of cycles spent in off-chip memory accesses. Recently, methods have been developed that transform memory layouts of data structures at compile-time to improve spatial locality of nested loops beyond current control-centric (loop nest-based) optimizations. Most of these data-centric transformations use a single static (program-wide) memory layout for each array. A disadvantage of these static layout-based locality enhancement strategies is that they might fail to optimize codes that manipulate arrays, which demand different layouts in different parts of the code. We introduce a new approach, which extends current static layout optimization techniques by associating different memory layouts with the same array in different parts of the code. We call this strategy "quasidynamic layout optimization." In this strategy, the compiler determines memory layouts (for different parts of the code) at compile time, but layout conversions occur at runtime. We show that the possibility of dynamically changing memory layouts during the course of execution adds a new dimension to the data locality optimization problem. Our strategy employs a static layout optimizer module as a building block and, by repeatedly invoking it for different parts of the code, it checks whether runtime layout modifications bring additional benefits beyond static optimization. Our experiments indicate significant improvements in execution time over static layout-based locality enhancing techniques.     

基于可伸缩矢量图形的手绘几何图形结构分析方法

复杂图形通常是由多个图元按一定几何关系构成,以基本图形的识别为基础,复杂图形识别重点在于图形元素之间的空间关系模式的判定。几何图形的图元构成复杂,难以直接利用启发式规则进行识别;而现有的结构分析方法太复杂,采用传统方法难以进行有效识别。针对手绘几何图形识别中结构分析这一核心技术问题,设计了一种几何图形结构描述模型,该模型通过对图元及其约束关系的形式化描述来表示图形,使用可伸缩矢量图形(SVG)标签存储图元及其约束,通过解析SVG标签来识别几何图形的形状及其内部关系,为图形结构分析提供了统一格式的表示方法。所提方法已经过自主开发的GeoSketch系统的验证,并取得良好效果。实验结果表明:该方法简洁、低维,方便进行图形形状及内部关系的判定。     

An Adaptive Approach to Schema Classification for Data Warehouse Modeling

Data warehouse （DW） modeling is a complicated task, involving both knowledge of business processes and familiarity with operational information systems structure and behavior. Existing DW modeling techniques suffer from the following major drawbacks -- data-driven approach requires high levels of expertise and neglects the requirements of end users, while demand-driven approach lacks enterprise-wide vision and is regardless of existing models of underlying operational systems. In order to make up for those shortcomings, a method of classification of schema elements for DW modeling is proposed in this paper. We first put forward the vector space models for subjects and schema elements, then present an adaptive approach with self-tuning theory to construct context vectors of subjects, and finally classify the source schema elements into different subjects of the DW automatically. Benefited from the result of the schema elements classification, designers can model and construct a DW more easily.     

VISOR: Schema-based scene analysis with structured neural networks

A novel approach to object recognition and scene analysis based on neural network representation of visual schemas is described. Given an input scene, the VISOR system focuses attention successively at each component, and the schema representations cooperate and compete to match the inputs. The schema hierarchy is learned from examples through unsupervised adaptation and reinforcement learning. VISOR learns that some objects are more important than others in identifying the scene, and that the importance of spatial relations varies depending on the scene. As the inputs differ increasingly from the schemas, VISOR's recognition process is remarkably robust, and automatically generates a measure of confidence in the analysis.     

Game level layout from design specification

The design of video game environments, or levels, aims to control gameplay by steering the player through a sequence of designer‐controlled steps, while simultaneously providing a visually engaging experience. Traditionally these levels are painstakingly designed by hand, often from pre‐existing building blocks, or space templates. In this paper, we propose an algorithmic approach for automatically laying out game levels from user‐specified blocks. Our method allows designers to retain control of the gameplay flow via user‐specified level connectivity graphs, while relieving them from the tedious task of manually assembling the building blocks into a valid, plausible layout. Our method produces sequences of diverse layouts for the same input connectivity, allowing for repeated replay of a given level within a visually different, new environment. We support complex graph connectivities and various building block shapes, and are able to compute complex layouts in seconds. The two key components of our algorithm are the use of configuration spaces defining feasible relative positions of building blocks within a layout and a graph‐decomposition based layout strategy that leverages graph connectivity to speed up convergence and avoid local minima. Together these two tools quickly steer the solution toward feasible layouts. We demonstrate our method on a variety of real‐life inputs, and generate appealing layouts conforming to user specifications.     

基于工程约束的产品参数化建模策略研究

在详述目前参数化建模技术的特点及其不足的基础上,提出了参数化建模系统工程应用化的实现策略,对设计参数的层次化定义、工程设计约束的分类及其动态化和智能化处理提出了有效的解决方案,并据此构造了基于工程约束的产品参数化建模系统。     

A space layout design model for concept generation using Function-based spatial planning and structure dynamic deployment

Concept design plays a critical role in product design, aiming to create conceptual schemes that satisfy various constraints. Among them, configuring the functions and structures that meet the user requirements and determining their spatial relationship is a necessary part of generating schemes. While existing methodologies of function and structure solution have been advanced recently, how to avoid overlap and interference in the space of functions and structures when generating schemes so as to maximize the use of the workspace and achieve the functionality of the product remains challenging. To address this issue, a space layout design model for concept generation using function-based spatial planning and structure dynamic deployment is proposed in this study. In the functional analysis phase, a function-based spatial zoning model is created for the functions, and establishing mappings for the spatial relationships and the zones in the space to generate the layout solution by extending and integrating zoned space. After generating conceptual structure, coordinate transformation based position deployment and trajectory analysis based motion space deployment methods are used to deploy spatial layout of the structures. A case study of a machine for electrical insulator detection that includes the integration and interaction of multiple components in space is introduced to demonstrate the feasibility of the proposed model and method.     

Recursive array layouts and fast matrix multiplication

The performance of both serial and parallel implementations of matrix multiplication is highly sensitive to memory system behavior. False sharing and cache conflicts cause traditional column-major or row-major array layouts to incur high variability in memory system performance as matrix size varies. This paper investigates the use of recursive array layouts to improve performance and reduce variability. Previous work on recursive matrix multiplication is extended to examine several recursive array layouts and three recursive algorithms: standard matrix multiplication and the more complex algorithms of Strassen (1969) and Winograd. While recursive layouts significantly outperform traditional layouts (reducing execution times by a factor of 1.2-2.5) for the standard algorithm, they offer little improvement for Strassen's and Winograd's algorithms. For a purely sequential implementation, it is possible to reorder computation to conserve memory space and improve performance between 10 percent and 20 percent. Carrying the recursive layout down to the level of individual matrix elements is shown to be counterproductive; a combination of recursive layouts down to canonically ordered matrix tiles instead yields higher performance. Five recursive layouts with successively increasing complexity of address computation are evaluated and it is shown that addressing overheads can be kept in control even for the most computationally demanding of these layouts.     

异构磁盘阵列RAID5结构数据布局研究

由于应用需求的快速发展以及网络存储系统的出现,因此异构磁盘阵列的变得越来越常见。RAID5由于较高的性能和可靠性以及较低的代价,是应用最为广泛的RAID结构。目前对异构磁盘阵列RAID5结构的研究,重点主要放在充分利磁盘存储空间以及对性能的定性研究。论文提出了一种异构磁盘阵列RAID5结构数据布局优化方法,该方法充分考虑异构磁盘的相对容量和性能,以及校验单元的散布对RAID5小数据写性能的影响,可以生成负载均匀分布或接近均匀分布的布局。仿真实验结果表明,对于多用户小数据访问模式,优化布局的性能明显优于简单RAID5布局,且具有更高的伸缩性。     

MIQP‐based Layout Design for Building Interiors

We propose a hierarchical framework for the generation of building interiors. Our solution is based on a mixed integer quadratic programming (MIQP) formulation. We parametrize a layout by polygons that are further decomposed into small rectangles. We identify important high‐level constraints, such as room size, room position, room adjacency, and the outline of the building, and formulate them in a way that is compatible with MIQP and the problem parametrization. We also propose a hierarchical framework to improve the scalability of the approach. We demonstrate that our algorithm can be used for residential building layouts and can be scaled up to large layouts such as office buildings, shopping malls, and supermarkets. We show that our method is faster by multiple orders of magnitude than previous methods.     

Visualization and User-Modeling for Browsing Personal Photo Libraries

We present a user-centric system for visualization and layout for content-based image retrieval. Image features (visual and/or semantic) are used to display retrievals as thumbnails in a 2-D spatial layout or “configuration” which conveys all pair-wise mutual similarities. A graphical optimization technique is used to provide maximally uncluttered and informative layouts. Moreover, a novel subspace feature weighting technique can be used to modify 2-D layouts in a variety of context-dependent ways. An efficient computational technique for subspace weighting and re-estimation leads to a simple user-modeling framework whereby the system can learn to display query results based on layout examples (or relevance feedback) provided by the user. The resulting retrieval, browsing and visualization can adapt to the user's (time-varying) notions of content, context and preferences in style and interactive navigation. Monte Carlo simulations with machine-generated layouts as well as pilot user studies have demonstrated the ability of this framework to model or “mimic” users, by automatically generating layouts according to their preferences.     

Interactive Modeling of City Layouts using Layers of Procedural Content

In this paper, we present new solutions for the interactive modeling of city layouts that combine the power of procedural modeling with the flexibility of manual modeling. Procedural modeling enables us to quickly generate large city layouts, while manual modeling allows us to hand‐craft every aspect of a city. We introduce transformation and merging operators for both topology preserving and topology changing transformations based on graph cuts. In combination with a layering system, this allows intuitive manipulation of urban layouts using operations such as drag and drop, translation, rotation etc. In contrast to previous work, these operations always generate valid, i.e., intersection‐free layouts. Furthermore, we introduce anchored assignments to make sure that modifications are persistent even if the whole urban layout is regenerated.