Analysing students' shared activity while modeling a biological process in a computer-supported educational environment

Abstract  This paper reports on a case study with three dyads of high school students (age 14 years) each collaborating on a plant growth modeling task in the computer-supported educational environment ' ModelsCreator '. Following a qualitative line of research, the present study aims at highlighting the ways in which the collaborating students as well as the facilitator who supported them are engaged in the computer-based modeling 'activity'. The analysis is carried out with a two-level analytic tool that has been derived within the theoretical framework of 'activity theory'. Our results show that a wide range of modeling 'operations' is activated in the context of the three major modeling 'actions' of 'analysis', 'synthesis' and 'testing-interpreting', which take place in the light of the facilitator-driven 'action' of cognitive and technical support. Moreover, these actions are combined into 'modeling units' of various forms which are repeated several times until the modeling process comes to an end. These many-fold repeats of the 'modeling unit' appear to shape a pattern which characterizes the computer-supported shared 'activity' as a whole.     

Context-aware garment modeling from sketches

Modeling of realistic garments is essential for creating believable virtual environments. Sketch-based modeling of garments presents an appealing, easy to use alternative to the established modeling approaches which are time consuming and require significant tailoring expertise. Unfortunately, the results created using existing sketch-based methods lack realism. Driven by human perception of garment sketches, we propose a context-aware garment sketch interpretation based on a set of observations about key factors that affect the shape of garments. Based on this analysis we develop a geometric method for sketch-based modeling of garments which obtains more realistic results than previous techniques. We demonstrate the effectiveness of our method on a variety of inputs and validate our approach via a user study where viewers were asked to compare the believability of our outputs versus previous ones.     

A ‘context-aware’ and agent-centric perspective for the alignment between individuals and organizations

The enterprise modeling field aims at representing organizations from several, inter-related perspectives. A number of enterprise modeling frameworks have been developed providing models, methods and tools that enable to communicate the structure and processes of organizations. These frameworks have been used both for systems development and organizational analysis ends, where the latter mainly focuses process (re)design efforts. We argue that enterprise modeling frameworks can be used for other kinds of organizational analysis. In particular, they can be used to capture and model work practices, human multitasking at work, and to compare models describing pre-defined behavior with actual execution.     

三维CAD 混合建模技术研究

三维数字化建模主要有两种技术：一是参数化建模,二是直接建模。但这 两种技术在实际应用中均存在缺陷。论文将两种建模方法融合在一起形成混合建模技术,能 更好地体现设计者的意图,提高设计效率。     

三维地质模型分析概述

由于三维地质建模需要对矿体的品位等属性信息进行详细的描述,所以三维地学建模须采用基于体元的方法建模,也可以由表面模型栅格化为体元模型。综述了现在常用的三维地质建模的一般方法,实体模型、四面体、块体模型、结构实体几何、似三棱柱等,并对各自的优缺点进行了分析,着重介绍了基于体元的建模方法,可为三维地质建模初学者提供一定的参考。     

A procedure for building product models

The application of product modeling in manufacturing companies raises the important question of how to model product knowledge in a comprehensible and efficient way. An important challenge is to qualify engineers to model and specify IT-systems (product models) to support their specification activities. A basic assumption is that engineers have to take the responsibility for building product models to be used in their domain. To do that they must be able to carry out the modeling task on their own without any need for support from computer science experts. This paper presents a set of simple, easily adaptable concepts and methods for modeling product knowledge. The concepts and methods are based on well-defined concepts and methods from data modeling (object oriented analysis) and domain modeling (product modeling). The concepts are general and can be used for modeling all types of specifications in the different phases in the product life cycle. The modeling techniques presented have been tested in different companies and have proved to work.     

MuscleBuilder: A modeling tool for human anatomy

A traditional multi-layered approach is adopted to human body modeling and deformation. The model is split into three general anatomical structures: the skeleton, musculature and skin. It is shown that each of these layers is modeled and deformed by using fast, procedural, ad-hoc methods that can painlessly be reimplemented. The modeling approach is generic enough to handle muscles of varying shape, size and characteristics and does not break in extreme skeleton poses. It is also described that the integrated MuscleBuilder system whose main features are: i) easy and quick creation of muscle deformation models; ii) automatic deformation of an overlying skin. It is shown that visually realistic results can be obtained at interactive frame rates with very little input from the designer.     

A Curvature and Density‐based Generative Representation of Shapes

This paper introduces a generative model for 3D surfaces based on a representation of shapes with mean curvature and metric, which are invariant under rigid transformation. Hence, compared with existing 3D machine learning frameworks, our model substantially reduces the influence of translation and rotation. In addition, the local structure of shapes will be more precisely captured, since the curvature is explicitly encoded in our model. Specifically, every surface is first conformally mapped to a canonical domain, such as a unit disk or a unit sphere. Then, it is represented by two functions: the mean curvature half‐density and the vertex density, over this canonical domain. Assuming that input shapes follow a certain distribution in a latent space, we use the variational autoencoder to learn the latent space representation. After the learning, we can generate variations of shapes by randomly sampling the distribution in the latent space. Surfaces with triangular meshes can be reconstructed from the generated data by applying isotropic remeshing and spin transformation, which is given by Dirac equation. We demonstrate the effectiveness of our model on datasets of man‐made and biological shapes and compare the results with other methods.     

Location-based services and GIS in perspective

This paper examines location-based services (LBS) from a broad perspective involving definitions, characteristics, and application prospects. We present an overview of LBS modeling regarding users, locations, contexts and data. The LBS modeling endeavors are cross-examined with a research agenda of geographic information science. Some core research themes are briefly speculated.     

SOA全生命周期建模方法综述

在介绍SOA(面向服务的架构)项目实施过程的基础上,从SOA全生命周期的视角,着重从方法论上对实施SOA项目所涉及到的业务流程建模、服务建模、数据建模、服务集成建模和业务监控建模进行了分析与评述,并提供了一些新的解决思路,同时指出了SOA建模领域的一些研究热点及趋势。     

树的建模技术研究综述与展望

树的建模技术是计算机图形学近年来研究的热点问题之一.侧重从计算机图形学的研究角度,对树的建模技术分别从基于规则的树建模技术、基于草图的树建模技术、基于图像的树建模技术3个方面进行了总结和综述,介绍了近年来提出的典型的树建模方法及最新研究进展,对其中涉及的关键技术进行了总结分析,给出了这些技术的基本思想、局限性和使用范围,并加以分析比较,最后对树的建模技术的未来研究方向给出展望.     

AML与面向对象建模

在面向对象建模中 ,状态机模型的继承是对象行为继承的重要组成部分 .为便于理解子类型的状态机模型与其父类型的状态机模型间的关系 ,我们研究了一种状态机模型及其继承的描述技术 ,从一定程度上解决了现有的状态机模型继承的描述技术中存在的一些问题 .本文在分析 AML中支持面向对象特征的主要设施的基础上 ,着重讨论了状态机模型的继承问题 .     

浅谈实体建模：历史、现状与未来

实体建模技术是 CAD 软件的“功能心脏”,相关基础理论与算法是 CAD 发展历史上最关键的成 果之一,成功回答了为使计算机能够辅助产品设计与制造,需在计算机中存什么几何信息以及怎么存的问题。 本文对实体建模的主要历史发展脉络做了简要介绍,同时对各发展阶段的关键问题以及研究现状进行了讨论, 最后选取了 3 个方向对实体建模的未来做出展望, 重点关注从 Computer-Aided Design 到 Computer-Automated Design 的发展趋势。     

Developing empirical models from observational data using artificial neural networks

Computer-integrated manufacturing requires models of manufacturing processes to be implemented on the computer. Process models are required for designing adaptive control systems and selecting optimal parameters during process planning. Mechanistic models developed from the principles of machining science are useful for implementing on a computer. However, in spite of the progress being made in mechanistic process modeling, accurate models are not yet available for many manufacturing processes. Empirical models derived from experimental data still play a major role in manufacturing process modeling. Generally, statistical regression techniques are used for developing such models. However, these techniques suffer from several disadvantages. The structure (the significant terms) of the regression model needs to be decided a priori. These techniques cannot be used for incrementally improving models as new data becomes available. This limitation is particularly crucial in light of the advances in sensor technology that allow economical on-line collection of manufacturing data. In this paper, we explore the use of artificial neural networks (ANN) for developing empirical models from experimental data for a machining process. These models are compared with polynomial regression models to assess the applicability of ANN as a model-building tool for computer-integrated manufacturing.Operated for the United States Department of Energy under contract No. DE-AC04-76-DP00613.     

3D树木建模技术研究进展

3D树木建模一直都是计算机图形学、计算机视觉、虚拟现实等领域最具有挑战性的研究方向之一,国外学者在该领域做了大量研究工作,但3D树木建模综述性文章的缺乏成为其发展的制约因素。侧重从计算机视觉的角度,将当前国内外经典的3D树木建模方法分为基于图像,基于规则和基于草图等三类,并跟踪了最新的3D树木建模技术进展,对他们的成果进行了深入剖析,重点阐述3D树木建模关键技术。最后,分析和比较了几种主要的3D树木建模技术,提出轻量化3D树木建模技术是今后虚拟场景中的交互应用的发展趋势。此外,根据当前研究的难点提出了基于单张图像的轻量化混合建模的研究思路。     

基于时间戳的企业时态化建模及应用

为了支持企业历史信息等与时间特征相关的建模,提出了在现有企业建模过程中引入基于时间戳的时态化扩展建模,其中包括对象属性、对象、对象间关系的快照化和时态化等概念及其形式化定义,并在UML基础上构建了一种时态化扩展的图形化表示.最后还分析了模型中时间戳的特殊语义及其实现策略.     

Multi-volume CAD modeling for heterogeneous object design and fabrication

The current computer-aided technologies in disign and product development,the evolution of CAD modeling,and a framework of multi-volume CAD modeling system for heterogeneous object design and fabrication are presented in this paper.The multi-volume CAD modeling system is presented based on nonmanifold topological elements.Material identifications are defined as design attributes introduced along with geometric and topological information at the design stage.Extended Euler operation and reasoning Boolean operations for merging and extraction are executed according to the associated material identifications in the developed multi-volume modeling system for heterogeneous object.An application example and a pseudo-processing algorithm for prototyping of heterogeneous structure through solid free-form fabrication are also described.     

3D空间复杂楼梯面可视化快速参数建模

空间复杂楼梯面的智能化建模问题是建筑、装饰等行业的难点、热点问题.本文以AutoCAD VBA作为开发工具,给出3D空间复杂楼梯面可视化参数快速建模方法,并对复杂楼梯面的生成算法与技巧进行了研究,使空间复杂楼梯面模型的设计更具敏捷化、智能化和可交互性.开发的设计程序可作为AutoCAD命令嵌入到AutoCAD绘图软件中,以提高用户的设计效率.     

An embedded simulation approach for modeling the thermal conductivity of 2D nanoscale material

The thermal property of single layer graphene sheet is investigated in this work by using an embedded approach of molecular dynamics (MD) and soft computing method. The effect of temperature and Stone–Thrower–Wales (STW) defects on the thermal conductivity of graphene sheet is first analyzed using MD simulation. The data obtained using the MD simulation is then fed into the paradigm of soft computing approach, multi-gene genetic programming (MGGP), which was specifically designed to model the response of thermal conductivity of graphene sheet with changes in system temperature and STW defect concentration. We find that our proposed MGGP model is able to model the thermal conductivity of graphene sheet very well which can be used to complement the analytical solution developed by MD simulation. Additionally, we also conducted sensitivity and parametric analysis to find out specific influence and variation of each of the input system parameters on the thermal conductivity of graphene sheet. It was found that the STW defects has the most dominating influence on the thermal conductivity of graphene sheet.     

Improving Phoneme Classification Performance Using Observation Context–Dependent Segment Models

This article describes a novel method that models the correlation among acoustic observations in contiguous speech segments. The basic idea behind the method is that acoustic observations are conditioned not only on the phonetic context but also on the preceding acoustic segment observation. The correlation between consecutive acoustic observations is modeled by mean trajectory polynomial segment models (PSM). This method is an extension of conventional segment modeling approaches in that it describes the correlation of acoustic observations not only inside segments but also between contiguous segments. It is also a generalization of phonetic context (e.g., triphone) modeling approaches because it can model acoustic context and phonetic context at the same time. Using the proposed method in a speaker-independent phoneme classification test resulted in a 7 to 9% relative reduction of error rate as compared with the traditional triphone segmental model system and a 31% reduction as compared with a similar triphone hidden Markov model (HMM) system.