Parallel Programming of Multi-processor SoC: A HW–SW Interface Perspective

For the design of classic computers the parallel programming concept is used to abstract HW/SW interfaces during high level specification of application software. The software is then adapted to existing multiprocessor platforms using a low level software layer that implements the programming model. Unlike classic computers, the design of heterogeneous MPSoC includes also building the processors and other kind of hardware components required to execute the software. In this case, the programming model hides both hardware and software refinements. This paper deals with parallel programming models to abstract both hardware and software interfaces in the case of heterogeneous MPSoC design. Different abstraction levels will be needed. For the long term, the use of higher level programming models will open new vistas for optimization and architecture exploration like CPU/RTOS tradeoffs.     

On partitioning and mapping for hypercube computing

Designing efficient parallel algorithms in a message-based parallel computer should consider both time-space tradeoffs and computation-communication tradeoffs. In order to balance these tradeoffs and achieve the optimal performance of an algorith, one has to consider various design parameters such as the number of processors required and the size of partitions. In this paper, we demonstrate that, for certain data parallel algorithms, it is possible to determine these design parameters analytically. To serve as a basis for the discussions that follow, a simple model for the NCUBE hypercube computer is introduced. Using this model, we use two examples, array summation and matrix multiplication, to illustrate how their performance can be modeled. By optimizing these expressions, one is able to determine optimal design parameters which arrive at efficient execution. Experiments on a 64-node NCUBE verified the accuracy of the analytic results and are used to further support the discussions.This research was supported in part by the DARPA ACMP Project and in part by the NSF grant CCR-87-16833.     

Collaborative conversational interfaces

This paper proposes a method of designing human-computer speech interfaces based on principles of human conversation. It argues that conversation is the primary mode of language use and that it is fundamentally collaborative. Speech interfaces should therefore be designed to recreate the collaborative nature of natural conversations. The paper presents five strategies for designingcollaborative conversational interfaces, and it describes the principles of human-language use that underly these strategies. The paper also argues that collaborative conversational interfaces have a crucial advantage over other kinds of interfaces in that they are readily adaptive to different levels of experience and styles of use. The paper gives examples of collaborative conversational interfaces that we have developed, and discusses the ways in which these interfaces have been made adaptive.     

Comparing model-based and dynamic event-extraction based GUI testing techniques: An empirical study

Graphical user interfaces are pervasive in modern software systems, and to ensure their quality it is important to test them. Two primary classes of automated GUI testing approaches, those based on static models and those based on dynamic event-extraction, present tradeoffs in cost and effectiveness. For example, static model-based GUI testing techniques can create test cases that contain nonexecutable events, whereas dynamic event-extraction based GUI testing techniques can create larger numbers of duplicate test cases. To better understand the effects of these tradeoffs, we created a GUI testing framework that facilitates fair comparison of different GUI testing techniques, and we conducted a controlled experiment comparing representative versions of static-model based and dynamic event-extraction based testing techniques on several GUI-based Java applications. Our study reveals several cost and effectiveness tradeoffs between the techniques, with implications for research and practice.     

User interfaces for mobile content

The UI must be designed to facilitate the widespread and increased use of mobile content. Current UI approaches in the computing domain - such as windows, icons, menus, and pointing (WIMP) - are inadequate and inappropriate for mobile applications. Mobile device constraints pose several UI design challenges. UIs for emerging mobile devices consist of hardware and software combinations such as additional buttons for text input and special functional keys, touch-sensitive screens, audio/visual interfaces, and haptic interfaces to provide virtual-reality (VR) experiences. Analysts expect that third-generation mobile phones and beyond will be conduits for enormous amounts of multimedia content. Several major issues along a variety of dimensions must be addressed in the design and provision of content to these mobile devices. Because they are crucial for enhancing the user experience and enabling the effective consumption of mobile content, UIs are therefore among the major issues that need further study and work.     

Dimensionality Reduction on Multi-Dimensional Transfer Functions for Multi-Channel Volume Data Sets

The design of transfer functions for volume rendering is a non-trivial task. This is particularly true for multi-channel data sets, where multiple data values exist for each voxel, which requires multi-dimensional transfer functions. In this paper, we propose a new method for multi-dimensional transfer function design. Our new method provides a framework to combine multiple computational approaches and pushes the boundary of gradient-based multi-dimensional transfer functions to multiple channels, while keeping the dimensionality of transfer functions at a manageable level, i.e., a maximum of three dimensions, which can be displayed visually in a straightforward way. Our approach utilizes channel intensity, gradient, curvature and texture properties of each voxel. Applying recently developed nonlinear dimensionality reduction algorithms reduces the high-dimensional data of the domain. In this paper, we use Isomap and Locally Linear Embedding as well as a traditional algorithm, Principle Component Analysis. Our results show that these dimensionality reduction algorithms significantly improve the transfer function design process without compromising visualization accuracy. We demonstrate the effectiveness of our new dimensionality reduction algorithms with two volumetric confocal microscopy data sets.     

WaterCalls: an ambient call queue for cooperation between emergency service centres

This paper presents some design-oriented reflections about a design idea—WaterCalls. This design concept is informed by findings from an ethnographic study of emergency service work. Two main components constitute WaterCalls—an ambient display consisting of bowls with water and a call queue in a graphical interface. The purpose is to support cooperation between several operators who work at different emergency service centres. One benefit of ambient displays in the emergency service centre is that information that is currently not available in the setting may be displayed in an unobtrusive way. In this paper, we suggest that it is important to consider how the ambient displays come into real use and how they fit into the work people actually do, namely, their work practices. For the development of interfaces like this, it is crucial to take into consideration how they are used in combination with more traditional graphical interfaces and other artefacts.     

From dialogue to monologue and back: Middle spaces in computer-mediated learning

The authors develop a framework for the design of tools to mediate collaboration intended to lead to learning. We identify two categories of media that are common in computer-supported collaborative learning and software in general: communication media and information media. These two types of media are then mapped onto two types of social activities in which learning is grounded: dialogue and monologue. Drawing on literature in learning theory, we suggest the need for interfaces that help students to transition from dialogue to monologue and back again. We examine in detail two cases of students participating in a computer-mediated science learning activity that involved technologies designed to support this transition, and suggest ways that the “middle space” can be supported with software and activities that transcend some of the traditional tradeoffs associated with information and communication interfaces.     

Contextual multi-dimensional browsing

Browsing efficiency depends to a large extent on the organization of the information being browsed. An emerging method of organizing Web content, called multi-faceted categorization, adopts a flat structure and treats different facets of the browsed content as equal and independent. The advantage of this structure is that it allows users to slice and dice the information space from any of the facets they wish to browse, and in any arbitrary order, thereby facilitating so-called multi-dimensional browsing. However, because of limited human information processing capacities, too many choices and too much browsing freedom tend to disorient users and increase the difficulty of information gathering. A more effective means of organizing information is therefore needed.In the literature, it is well documented that context plays a crucial role in making relevance judgments about categorical attributes. Since browsing always occurs in relation to certain contexts, we propose taking context into account for multi-faceted categorization to help organize different facets of information on the browsing interface. Our experiment results demonstrate that the context-sensitive arrangement of categories helps users find information more efficiently. Moreover, users perceive the context-sensitive interface as easier to use than non-contextual interfaces.     

Properties of single input,two output feedback systems

We describe properties of linear multivariable feedback systems for which the plant has a single control input and two measured outputs. Particular attention is paid to 'algebraic' design tradeoffs that occur between different feedback properties at the same frequency. To describe these tradeoffs, we use concepts of plant and controller direction and alignment. We show that if plant/controller alignment is poor, then closed loop response to noise and disturbances will be large unless the loop gain is sufficiently small. Moreover, the closed loop system will exhibit large interactions. We also describe a dual set of results that are applicable to feedback systems for which the plant has two control inputs and a single measured output.     

面向工业4.0的多维视频监控系统设计

针对多维视频监控受到图像噪声的影响,导致多维视频的质量变差,以提高多维视频图像的质量为目的,提出了面向工业4.0的多维视频监控系统设计;在第四次工业革命的背景下,利用多维视频采集器设计和监控网络传输接口设计,完成了系统的硬件设计;确定多维视频背景中的图片像素点,提取多维视频背景,通过低通滤波来阻止视频更新的影响,根据帧多维视频的检测结果来更新多维视频的背景,提出多维视频跟踪算法,完成了系统的软件设计,实现了多维视频的监控;测试结果表明,与其他两个多维视频监控系统相比,面向工业4.0的多维视频监控系统可以将噪声消除掉80%~90%,平均压缩比为80.004:1,平均分辨率大约为533*533 dpi,可以获得较高质量的多维视频图像。     

Numerical simulation of Richtmyer–Meshkov instability driven by imploding shocks

In this paper, the classical piecewise parabolic method (PPM) is generalized to compressible two-fluid flows, and is applied to simulate Richtmyer–Meshkov instability (RMI) induced by imploding shocks. We use the compressible Euler equations together with an advection equation for volume fraction of one fluid component as model system, which is valid for both pure fluid and two-component mixture. The Lagrangian-remapping version of PPM is employed to solve the governing equations with dimensional-splitting technique incorporated for multi-dimensional implementation, and the scheme proves to be non-oscillatory near material interfaces. We simulate RMI driven by imploding shocks, examining cases of single-mode and random-mode perturbations on the interfaces and comparing results of this instability in planar and cylindrical geometries. Effects of perturbation amplitude and shock strength are also studied.     

A multi-dimensional solver for the steady Euler equations

In this paper a numerical algorithm for the solution of the multi-dimensional steady Euler equations in conservative and non-conservative form is presented. Most existing standard and multi-dimensional schemes use flux balances with assumed constant distribution of variables along each cell edge, which interfaces two grid cells. This assumption is believed to be one of the main reasons for the limited advantage gained from multi-dimensional high order discretisations compared to standard one-dimensional ones. The present algorithm is based on the optimisation of polynomials describing the distribution of flow variables in grid cells, where only polynomials that satisfy the Euler equations in the entire grid cell can be selected. The global solution is achieved if all polynomials and by that the flow variables are continuous along edges interfacing neighbouring grid cells. A discrete approximation of a given spatial order is converged if the deviation between polynomial distributions of adjacent grid cells along the interfacing edge of the cells is minimal. Results from the present scheme between first and fifth order spatial accuracy are compared to standard first and second order Roe computations for simple test cases demonstrating the gain in accuracy for a number of sub- and supersonic flow problems.     

基于VaR技术的多维数据交互可视化研究

传统多维数据可视化技术比如平行坐标法等在表达多维数据时,对各个不同数据维之间的数据表达式会产生一定的混乱,同时对各维的相关性与交互表达比较困难。研究并设计了基于VaR技术的多维数据交互可视化小工具,其充分利用VaR技术所实现的丰富导航与选择、突出等工具来形象突出显示与表达多维数据中某一特定维的数据,同时应用MDS算法,在二维屏幕上各点的相对位置关系来表示多维数据中各维的相关性。     

Efficient numerical approximation of compressible multi-material flow for unstructured meshes

We consider the numerical approximation of multi-dimensional multi-material flows. This is a difficult topic related to the numerical smearing of contact discontinuities (or material interfaces or slip lines). Any Eulerian scheme will produce an artificial mixing zone. In this artificial mixture, the computation of thermodynamical variables (pressure, sound speed, temperature, …) is difficult to achieve correctly. For the stiff cases considered in this paper, with solid-liquid-gas interfaces, small errors on the thermodynamical variables lead to the blow up of the computation in many cases. In this paper, we review and explain this problem, then we propose solutions for 1D and 2D flows. Contrarily to front-tracking techniques, our schemes use the same formulation everywhere on the mesh. We provide several examples with the stiffened gas equation of state (EOS): inert materials (water-air), and chemically reactive materials (solid explosive-Plexiglass-air).     

WalkMap: Developing an augmented reality map application for wearable computers

We have designed, implemented, and evaluated a map application for wearable computer users. Our application, called WalkMap, is targeted at a walking user in an urban environment, offering the user both navigational aids as well as contextual information. WalkMap uses augmented reality techniques to display a map on the surrounding area on the user's head-worn display. WalkMap is constructed by the means of software development, user interface design and evaluations, and existing knowledge on how humans use maps and navigate. The key design driver in our approach is intuitivity of use. In this paper, we present the design and implementation process of our application, considering human-map interfaces, technical implementation, and human-computer interfaces. We identify some of the key issues in these areas, and present the way they have been solved. We also present some usability evaluation results.     

DTI:对于运动轨迹数据的新型索引结构

近年随着定位技术(Location-based Service)越来越广泛的使用,时空数据(Spatio-Temporal Data)大量的产生.如何有效的对这些数据的进行管理已经成为一个越来越受重视的问题.通常可以使用R-tree[1]结构对这类数据进行索引,然而,目前并不是所有的商业关系数据库都支持R-tree.因此,提出了DTI这种新型的基于B-tree结构的索引方法.DTI可以在几乎所有的关系数据库上进行实施.DTI使用Hilbert曲线处理空间维度.同时在时间维度上使用RI-tree进行处理.实验证明,DTI显著提高查询速度.     

Graphical and text-based design interfaces for parameter design of an I-beam,desk lamp,aircraft wing,and job shop manufacturing system

In this paper we describe four design optimization problems and corresponding design interfaces that have been developed to help assess the impact of fast, graphical interfaces for design space visualization and optimization. The design problems involve the design of an I-beam, desk lamp, aircraft wing, and job shop manufacturing system. The problems vary in size from 2 to 6 inputs and 2 to 7 outputs, where the outputs are formulated as either a multiobjective optimization problem or a constrained, single objective optimization problem. Graphical and text-based design interfaces have been developed for the I-beam and desk lamp problems, and two sets of graphical design interfaces have been developed for the aircraft wing and job shop design problems that vary in the number of input variables and analytical complexity, respectively. Response delays ranging from 0.0 to 1.5 s have been imposed in the interfaces to mimic computationally expensive analyses typical of complex engineering design problems, allowing us to study the impact of delay on user performance. In addition to describing each problem, we discuss the experimental methods that we use, including the experimental factors, performance measures, and protocol. The focus in this paper is to publicize and share our design interfaces as well as our insights with other researchers who are developing tools to support design space visualization and exploration.     

Interactive faceted search and exploration of open social media data on a touchscreen mobile phone

A central challenge of semantic ambient media applications is designing smart user interfaces that are able to dynamically deal with an a-priori unknown number of data categories and data instances received live from different Linked Open Data sources while at the same time being intuitive and easy to use. In the mobile world, this challenge is even more difficult as the mobile devices have limited interaction possibilities and smaller display size. In this paper, we tackle this challenge and present the user-centered, iterative design of a mobile application for faceted search and exploration of a large, multi-dimensional data set of open social media on a touchscreen mobile phone. The application is called Mobile Facets and provides live retrieval and interactive search and exploration of resources like places, persons, organizations, and events originating from different, integrated social media sources like DBpedia, Eventful, Upcoming, Flickr, and GeoNames. In contrast to existing work, we do not know in advance the number and type of data categories and data instances that will be received as the data is queried live from the sources. While developing Mobile Facets, we have applied a participatory design with a small group of five users. For the final prototype we have conducted a task-based, formative evaluation with 12 additional subjects to investigate the applicability and usability of our Mobile Facets application.