BACH:线性混成系统有界可达性模型检验工具

混成自动机的模型检验问题非常困难,即使是其中相对简单的一个子类--线性混成自动机,它的可达性问题仍然是不可判定的.现有的相关工具大都使用多面体计算来判定线性混成自动机状态空间的可达集,复杂度高、效率低,无法解决实际应用规模的问题.描述了一个面向线性混成系统有界可达性模型检验工具--BACH(bounded reacha...     

Computer Support for Social Awareness in Flexible Work

How do we conceptualize social awareness, and what support is needed to develop and maintain social awareness in flexible work settings? The paper begins by arguing the relevance of designing for social awareness in flexible work. It points out how social awareness is suspended in the field of tension that exists between the ephemerality and continuity of social encounters, exploring ways to construct identity through relationships by means of social encounters – notably those that are accidental and unforced. We probe into this issue through design research: In particular, we present three exploratory prototyping processes in an open office setting (examining the concepts of a shared calendar, personal panels, and ambient awareness cues). Field studies, conducted in parallel, have contributed to a conceptual deconstruction of CSCW concepts, resulting in a focus on cues to relatedness, to belonging, and to care. Analyzing these three prototypes in their microcosmic usage setting results in specific recommendations for the three types of applications with respect to social awareness. The experiences indicate that the metaphors a ‘shared mirror’ and ‘breadcrumbs’ are promising foundations on which to base further design. We present these analyses and suggest that the metaphors work because of their ability to map experiences from the physical space into conceptual experiences. We conclude that social awareness in flexible work must be constructed indirectly, presenting itself as an option, rather than as a consequence of being able to overhear and oversee.     

董灏：灵感启示

董灏,北京市建筑研究院国际工作室负责人、中央美院建筑学院教师。同广大“70后”一样,董灏也有很多他们对生活的共同记忆和感悟。铁臂阿童木、聪明的一休哥、神奇的花仙子还有上世纪末北京城的旧景……都是他童年的美好回忆。     

Chronos: a Performance Characterization Tool Inside the EDPEPPS Toolset

The EDPEPPS toolset is the fruit of a 10 man-year-research development and integrates many modules in order to predict and classify the execution times of C/PVM programs mapped on a cluster of heterogeneous workstations. In this project, a performance characterization tool called Chronos has been developed to model the processor and C instructions. Chronos can be used to characterize a wide range of machines as it is developed round a specialized benchmark. Chronos uses a parameter-based model and characterizes the machine and the program studied. Then, the execution predictor evaluates the time spent in each program block, according to a generic model of cache memory which simulates most of the CPU internal cache memory architecture. Chronos does not need any user's intervention as all the operations are automatic. The performance accuracy of Chronos is highlighted by a real processor-consuming sequential example.This tool can be used by designers to predict the average execution time of their applications quickly. Average percentage errors obtained from this tool are below 10%.     

柔性电子神经网络计算机结构和原理

本文以开发系统的观点描述了一种新的神经网络计算机体系结构，它以其可开发性和灵活性区别于其他各种神经网络计算机，应用于人工神经网络的研究过程。基于柔性神经网络计算机体系设计，文中提出了一种神经网络分解撕裂算法，为ＶＬＳＩ神经芯片的设计提供了一条新途径。在功能应用上，柔性电子神经网络计算机打破了其他神经网络计算机功能的针对性，为神经网络的研究，开发和应用提供较全面的支持。     

计算机学科柔性化人才培养模式研究

社会的飞速发展使计算机学科原有的人才培养模式凸显出种种不足,已经逐渐跟不上市场的需求。本文阐述了计算机学科现行培养模式的弊端,从课程体系、教学模式以及质量保障体系三方面论述了计算机学科柔性化人才培养模式,最后就需要注意的问题进行了探讨。     

Making Effective Decisions in Computer Architects Real-World: Lessons and Experiences with Godson-2 Processor Designs

Although the design of many kinds of microprocessors has been under developing for several decades,the computer architecture R&D community lacks well documented lessons and experiences about design decisions in the research literature.In this paper,we systematically present the design decisions we made during the designing and prototyping of Godson-2 series processors.The 250MHz Godson-2B,450MHz Godson-2C,and 1GHz Godson-2E processors that implement 64-bit,four-issue,out-of-order architecture were taped out in 2003,2004,and 2005,respectively.Each processor triples its predecessor in the SPEC CPU2000 rates.Our first-hand experiences and lessons gained from these designs would provide unique perspectives and insights that are not available in any existing text books and/or published papers.We summarize 10 critical lessons and experiences based on hundreds of our attempts at architectural and design optimizations for performance improvement of Godson-2 series processors.The issues include silicon-simulation correlation,design balancing,performance optimizing,and pico-architecture tuning.We conclude that persistent improvement,attitude towards work-on-silicon design, and insightful understanding of software and fabrication process are the three most important factors for designing a high performance processor with low energy consumption.     

一种用于电容层析成象三相流重建的神经网络算法

在对B-P网络激励函数作出修改的基础上,提出了充分利用ECT系统的测量数据对气/油/水三相流进行成象的方法.该图象重建算法具有概念简单,易于实施,成象速度快,抗噪能力强等优点.     

一个灵活的操作系统安全框架FMAC

当前,操作系统的安全需求越来越多样、灵活和具体,它们往往只描述系统中一小部分实体之问的约束,但对安全策略的灵活性厦定制的简洁性有较高的要求。传统的安全框架,如FLASK等,难于满足此类“轻量级”的安全需求。本文提出的FMAC框架专门面向此类安全需求,它定义了基于标记迁移系统LTS的安全策略模型,以规范和简化安全策略的定制。FMAC框架由通用的对象管理器模型和安全策略管理器模型组成。讨论了FMAC在Unix类操作系统中的实现,通过层次式的客体组织与基于角色的主体组织,普通用户可以方便快捷地定制出满足要求的轻量级安全策略。     

Flexible Real-Time Linux*: A Flexible Hard Real-Time Environment

This paper presents a framework appropriate for Flexible Real-Time Systems (FRTS) and a run-time support system based on that framework, called Flexible Real-Time Linux (FRTL). The framework proposes to build each task as a sequence of mandatory and optional components and to separate their execution in two scheduling levels. This approach is shown to provide both hard guarantees and flexible behavior. The FRTL system has been implemented by enhancing the original capabilities of Real-Time Linux (RT-Linux), while maintaining its predictability and efficiency features. This paper also shows a complete schedulability test on which all sources of overhead of the FRTL itself have been introduced. By applying this complete test, the designer is able to safely guarantee a real-time application running on the FRTL system.     

Computer courses for humanists: A survey

Conclusion I assume that with those courses reported in the previous surveys, those written up in various journals, and those mentioned in the returns to this survey, a high percentage of the significant computer courses for humanists (within the surveyed population) have been reported. The majority of questionnaires that were not returned (1640 or 87%) probably should be attributed to the fact that the respondents had nothing to report. The real value of these surveys rests in the diversity of the type of course reported. The English professor looking for help for a graduate level course and a humanities professor searching for some ideas for a freshman-level introductory course could both find what they are looking for in various areas of these surveys. while he completes aDoctor of Arts degree in English. This survey was supported by a grant from the Carnegie-Mellon University Program in Technology and Humanities.     

FlexPDA: A Flexible Programming Framework for Deep Learning Accelerators

There are a wide variety of intelligence accelerators with promising performance and energy efficiency, deployed in a broad range of applications such as computer vision and speech recognition. However, programming productivity hinders the deployment of deep learning accelerators. The low-level library invoked in the high-level deep learning framework which supports the end-to-end execution with a given model, is designed to reduce the programming burden on the intelligence accelerators. Unfortunately, it is inflexible for developers to build a network model for every deep learning application, which probably brings unnecessary repetitive implementation. In this paper, a flexible and efficient programming framework for deep learning accelerators, FlexPDA, is proposed, which provides more optimization opportunities than the low-level library and realizes quick transplantation of applications to intelligence accelerators for fast upgrades. We evaluate FlexPDA by using 10 representative operators selected from deep learning algorithms and an end-to-end network. The experimental results validate the effectiveness of FlexPDA, which achieves an end-to-end performance improvement of 1.620x over the low-level library.     

A Flexible System for Scheduling Drivers

A substantial part of the operating costs of public transport is attributable to drivers, whose efficient use therefore is important. The compilation of optimal work packages is difficult, being NP-hard. In practice, algorithmic advances and enhanced computing power have led to significant progress in achieving better schedules. However, differences in labor practices among modes of transport and operating companies make production of a truly general system with acceptable performance a difficult proposition. TRACS II has overcome these difficulties, being used with success by a substantial number of bus and train operators. Many theoretical aspects of the system have been published previously. This paper shows for the first time how theory and practice have been brought together, explaining the many features which have been added to the algorithmic kernel to provide a user-friendly and adaptable system designed to provide maximum flexibility in practice. We discuss the extent to which users have been involved in system development, leading to many practical successes, and we summarize some recent achievements.     

B-Spline Surfaces: A Tool for Computer Painting

B-splines make it possible to model shapes the way a sculptor models clay or plasticine,and their control points can be modified for a variety of effects.     

EasyXplorer: A Flexible Visual Exploration Approach for Multivariate Spatial Data

Exploring multivariate spatial data attracts much attention in the visualization community. The main challenge lies in that automatic analysis techniques is insufficient in discovering complicated patterns with the perspective of human beings, while visualization techniques are incapable of accurately identifying the features of interest. This paper addresses this contradiction by enhancing automatic analysis techniques with human intelligence in an iterative visual exploration process. The integrated system, called EasyXplorer, provides a suite of intuitive clustering, dimension reduction, visual encoding and filtering widgets within 2D and 3D views, allowing an inexperienced user to visually explore and reason undiscovered features with several simple interactions. Case studies show the quality and scalability of our approach in quite challenging examples.     

Beyond Schema Versioning: A Flexible Model for Spatio-Temporal Schema Selection

Schema versioning provides a mechanism for handling change in the structure of database systems and has been investigated widely, both in the context of static and temporal databases. With the growing interest in spatial and spatio-temporal data as well as the mechanisms for holding such data, the spatial context within which data items are formatted also becomes an issue. This paper presents a generalized model that accommodates temporal, spatial and spatio-temporal schema versioning within databases.