An Empirical Investigation Into Text Input Methods for Interactive Digital Television Applications

Nowadays there is a huge market emerging in the interactive digital TV realm. In this context, we need new and effective methods of user interaction, as the main interaction device is still the classical remote control. Remote controls are especially problematic when it comes to writing text, something needed in most applications. Thus, we have carried out an empirical investigation to find effective methods of text entry with remote controls. We analyze several methods by performing experiments based on a methodology in which a heterogeneous set of real users carries out several sequential tasks in an incremental process. We analyze entry speeds, error rates, learning profiles, and subjective impressions, taking into account the particular characteristics of the users. Our results show, for instance, that Multitap is a good method for simple texts. It is between 12% and 34% faster than the fastest virtual keyboard, depending on the age of the user. Nevertheless, when complex texts need to be written, virtual keyboards present the same or even better writing speeds (QWERTY is 13% faster) and with significant lower error rates (Multitap is 347% worse than QWERTY). We consider that our results are very interesting for researchers, designers of TV applications, and hardware vendors.     

Evaluation of Virtual Keyboards for Interactive Digital Television Applications

The development of the technologies behind Interactive Digital Television (IDTV) services has produced a new type of audience. Traditional viewers now become users as they may play an active role in front of the TV, for example, by choosing a video to be played on demand or by introducing text on an IDTV application. In these services, interactions need to be performed with a remote control, currently the main interaction device, or other devices such as keyboards or mice, which are not very popular in this environment. Nevertheless, although remote controls are essential tools for IDTV services, they are very limited when it comes to writing text. Thus, this study evaluated different alternatives to introduce text on an IDTV application with a remote control. A heterogeneous group of people was selected to write predefined sentences in Spanish in a test environment using three virtual keyboard layouts and the multitap mechanism. Their performance and subjective impressions reveal weaknesses and strengths of the evaluated methods. The article draws important conclusions about the usage of remote controls in IDTV applications, not only for the design of new applications but also for the research of new techniques to introduce text.     

Active Learning for Transductive Support Vector Machines with Applications to Text Classification

This paper presents a novel active learning approach for transductive support vector machines with applications to text classification. The concept of the centroid of the support vectors is proposed so that the selective sampling based on measuring the distance from the unlabeled samples to the centroid is feasible and simple to compute. With additional hypothesis, active learning offers better performance with comparison to regular inductive SVMs and transductive SVMs with random sampling,and it is even competitive to transductive SVMs on all available training data. Experimental results prove that our approach is efficient and easy to implement.     

互动电视业务数据源部署及频点管理和分配方法研究

传统互动电视业务数据源与IPQAM连接方式通常会带来业务数据流较大时延、抖动,以及诸多网络安全问题.为了缓解上述问题,本文提出了一种业务数据源与IPQAM直连部署方法.在此部署方法基础上提出一种频点管理和分配算法.仿真实验表明,该管理、分配方法能够很好地兼容本文提出的业务数据源部署方式和传统业务数据源部署方式,并在限制最大服务拒绝率情况下,可提供较高频点带宽利用率.     

A Generalization of Magic Squares with Applications to Digital Halftoning

A semimagic square of order n is an n×n matrix containing the integers 0,…,n ²−1 arranged in such a way that each row and column add up to the same value. We generalize this notion to that of a zero k×k -discrepancy matrix by replacing the requirement that the sum of each row and each column be the same by that of requiring that the sum of the entries in each k×k square contiguous submatrix be the same. We show that such matrices exist if k and n are both even, and do not if k and n are relatively prime. Further, the existence is also guaranteed whenever n=k ^m , for some integers k,m≥2. We present a space-efficient algorithm for constructing such a matrix. Another class that we call constant-gap matrices arises in this construction. We give a characterization of such matrices. An application to digital halftoning is also mentioned. A preliminary version of this paper appeared in Proceedings of International Symposium on Algorithms and Computation, Hong Kong, December, 2004. Part of the work on the paper has been carried out when B.A. was visiting JAIST. Work of B.A. on this paper was supported in part by NSF ITR Grant CCR-00-81964. Work of T.A. was partially supported by the Ministry of Education, Science, Sports and Culture, Grant-in-Aid for Scientific Research (B).     

基于GPU光线投射的多平面交互彩色体数据切割方法

基于代理多边形的3D纹理映射体绘制成像速度快,能够直接利用OpenGL剪切平面功能实现多平面实时切割,但成像质量不高.本文通过分析彩色数据场的不透明度转换函数,研究基于GPU的光线投射算法,用于数字人彩色体数据的快速高质量可视化.为了避免转换函数设计困难和不足,提出一种基GPU的多平面快速切割算法,能够实时清晰观察彩色体数据内部组织.实验结果表明:基于GPU的光线投射算成像质量高、速度快,该多平面交互切割方法能够清晰观察组织结构.     

An Initial Evaluation of Approaches to Building Entry for Large Robot Teams

Teams of robots offer potential reductions in risk for rescuers and improved rescue rates for search and rescue in collapsed buildings and other restricted environments. However, one aspect of deployment of such teams that is often overlooked is the initial entry of the robots into the building. If many robots enter the building from the same entrance, they are likely to interfere with each other and dramatically slow the initial phase of exploration. In this paper, we use a low fidelity simulation to evaluate several approaches to overcoming this initial congestion and identify heuristics that might allow the robots to most quickly clear the entry area and begin their actual mission. Our results show that unless the exits to the initial entry area are small, over a wide range of parameters, the most effective technique was for every robot to move in the direction of the longest open space it senses. In more cluttered environments with smaller exits, wall following, a strategy less dependent on the quality of sensing, proved more effective. Informal comparisons of these algorithms in a high fidelity simulation with limited trials and no variation in parameters suggested that simply promoting dispersion might be a more effective strategy for realistically complex dynamics.     

Applications of a New Property of Conics to Architecture: An Alternative Design Project for Rio de Janeiro Metropolitan Cathedral

This paper describes the mathematical discovery of a new property of conics which allows the development of numerous geometric projects for use in architectural and engineering applications. Illustrated is an architectural application in the form of an alternative project for Río de Janeiro Metropolitan Cathedral featuring the integration of a circular base and a cross in the top plane. Two alternative designs are presented for the cathedral, based on the choice of either the Latin Immisa or Greek cross.     

数传电台与GPRS相结合的水厂遥控系统研究和设计

针对城镇水厂供水系统,采用数传电台与GPRS相结合的远程遥控方式,完成井群水泵控制及供水管网流量压力等相关参数采集和传输;此外,根据供水管网分布广、管线长、管道泄漏精确定位难的特点,提出负压力波-流量法诊断供水管网泄漏的方案,实现供水系统参数实时采集、处理、无线传输及远程监控等功能。     

Maximum Principle for Optimal Boundary Control of Vibrating Structures with Applications to Beams

A maximum principle is derived for open-loop boundary control of one dimensional structures undergoing transverse vibrations. The optimal control law is obtained using a maximum principle and the applicability of the results to the boundary control of vibrating beams is demonstrated. The method of solution involves the transformation of the original problem into one with homogeneous boundary conditions for a general set of boundary forces and torques. An adjoint variable is introduced and used in the formulation of a Hamiltonian function which in turn leads to the derivation of the maximum principle. The effectiveness of the proposed control mechanism is illustrated numerically and it is shown that the implementation of the optimal boundary control using one force actuator can lead to substantial decrease in the dynamic response of a vibrating beam.     

Methods for adaptive combination of classifiers with application to recognition of handwritten characters

This paper discusses two techniques for improving the recognition accuracy for online handwritten character recognition: committee classification and adaptation to the user. Combining classifiers is a common method for improving recognition performance. Improvements are possible because the member classifiers may make different errors. Much variation exists in handwritten characters, and adaptation is one feasible way of dealing with such variation. Even though adaptation is usually performed for single classifiers, it is also possible to use adaptive committees. Some novel adaptive committee structures, namely, the dynamically expanding context (DEC), modified current best learning (MCBL), and class-confidence critic combination (CCCC), are presented and evaluated. They are shown to be able to improve on their member classifiers, with CCCC offering the best performance. Also, the effect of having either more or less diverse sets of member classifiers is considered.Received: 17 September 2002, Accepted: 22 October 2002, Published online: 4 July 2003     

Geometrical Optimization of Parallel Mechanisms Based on Natural Frequency Evaluation: Application to a Spherical Mechanism for Future Space Applications

This paper presents an optimization procedure conceived to design parallel mechanisms (PMs) with legs of constant and/or variable length connected, at their endpoints, to a fixed base and a movable platform through universal and spherical joints, respectively. In the proposed procedure, the first natural frequency of the mechanism is the objective function to be maximized. The optimization problem is formulated by using dimensionless variables in order to identify the optimal geometry independently of mechanism size, platform density, and leg cross-sectional area and material. As a case study, the procedure is employed to find the optimal geometry of a 2-DOF spherical PM to be used as an orienting device in future space missions.      

A workflow for handling heterogeneous 3D models with the TOUGH2 family of codes: Applications to numerical modeling of CO2 geological storage

This paper is addressed to the TOUGH2 user community. It presents a new tool for handling simulations run with the TOUGH2 code with specific application to CO₂ geological storage. This tool is composed of separate FORTRAN subroutines (or modules) that can be run independently, using input and output files in ASCII format for TOUGH2. These modules have been developed specifically for modeling of carbon dioxide geological storage and their use with TOUGH2 and the Equation of State module ECO2N, dedicated to CO₂-water-salt mixture systems, with TOUGHREACT, which is an adaptation of TOUGH2 with ECO2N and geochemical fluid-rock interactions, and with TOUGH2 and the EOS7C module dedicated to CO₂-CH₄ gas mixture is described. The objective is to save time for the pre-processing, execution and visualization of complex geometry for geological system representation. The workflow is rapid and user-friendly and future implementation to other TOUGH2 EOS modules for other contexts (e.g. nuclear waste disposal, geothermal production) is straightforward. Three examples are shown for validation: (i) leakage of CO₂ up through an abandoned well; (ii) 3D reactive transport modeling of CO₂ in a sandy aquifer formation in the Sleipner gas Field, (North Sea, Norway); and (iii) an estimation of enhanced gas recovery technology using CO₂ as the injected and stored gas to produce methane in the K12B Gas Field (North Sea, Denmark).     

Evaluation of multiple muscle loads through multi-objective optimization with prediction of subjective satisfaction level: Illustration by an application to handrail position for standing

Proposed here is an evaluation of multiple muscle loads and a procedure for determining optimum solutions to ergonomic design problems. The simultaneous muscle load evaluation is formulated as a multi-objective optimization problem, and optimum solutions are obtained for each participant. In addition, one optimum solution for all participants, which is defined as the compromise solution, is also obtained. Moreover, the proposed method provides both objective and subjective information to support the decision making of designers. The proposed method was applied to the problem of designing the handrail position for the sit-to-stand movement. The height and distance of the handrails were the design variables, and surface electromyograms of four muscles were measured. The optimization results suggest that the proposed evaluation represents the impressions of participants more completely than an independent use of muscle loads. In addition, the compromise solution is determined, and the benefits of the proposed method are examined.