Construction performance monitoring via still images,time-lapse photos,and video streams: Now,tomorrow, and the future

Timely and accurate monitoring of onsite construction operations can bring an immediate awareness on project specific issues. It provides practitioners with the information they need to easily and quickly make project control decisions. Despite their importance, the current practices are still time-consuming, costly, and prone to errors. To facilitate the process of collecting and analyzing performance data, researchers have focused on devising methods that can semi-automatically or automatically assess ongoing operations both at project level and operation level. A major line of work has particularly focused on developing computer vision techniques that can leverage still images, time-lapse photos and video streams for documenting the work in progress. To this end, this paper extensively reviews these state-of-the-art vision-based construction performance monitoring methods. Based on the level of information perceived and the types of output, these methods are mainly divided into two categories (namely project level: visual monitoring of civil infrastructure or building elements vs. operation level: visual monitoring of construction equipment and workers). The underlying formulations and assumptions used in these methods are discussed in detail. Finally the gaps in knowledge that need to be addressed in future research are identified.     

搜索:本期热点

<正>PayScale让薪资更透明"Our original vision was to provide transparency to employees and employers alike. For the first time,     

Multiperiod forecasting in stock markets: a paradox solved

One of the most striking results on asset pricing in the last 20 years is the better forecastability of long-horizon returns over one-step return forecasts. This could seem a paradox, given that the further our forecast horizon the greater the uncertainty we are bound to face. This point can be found in Campbell and Shiller [Journal of Finance 43 (1988) 661; Journal of Finance 40 (1985) 793; American Economic Review 76 (1986) 1142] among others. In this paper, we offer an alternative explanation to this “forecast paradox ” that is in agreement with Kim et al. [Review of Economic Studies 30 (1992) 25], who found that the negative serial correlation in long-horizon returns depends very much on the sample choice. Our explanation is based on the existence of simultaneous shifts in the time series of the equilibrium stock price and dividends. This explanation relies on the concept of co-breaking [D.F. Hendry, A theory of co-breaking, Mimeo, Nuffield College, Oxford, 1995.]. We put forward a stochastic present value model, in which we are able to show how shifts in the process for dividends lead to shifts in the equilibrium stock price.This has important implications for multiperiod forecasting, as we demonstrate in this paper. An empirical application supports our results. In our empirical application, we model earning, dividends, stock prices, and the risk-free interest in the United States from 1926 to 1985. We can distinguish three different historical periods where the process for dividends and the equilibrium stock prices are characterized by different properties in terms of their means and variances. Our empirical model is extended to a forecasting exercise where the “forecast paradox” is solved.     

The Blaster Worm: Then and Now

In August of 2003 the Blaster worm struck the Internet, infecting at least 100,000 Microsoft Windows systems and causing millions of dollars in damages. In spite of considerable cleanup efforts, an antiworm aimed at patching systems, and a widely downloaded clean-up tool from Microsoft, the worm is still very much alive. In this article we describe observations of the Blaster worm from its onset in 2003 to its continued persistence a year later.     

Dirichlet series and simultaneous observability: two problems solved by the same approach

In a classical paper, Ingham gave a simple proof of an important theorem of Pólya on singular points of Dirichlet series under a uniform gap assumption on the exponents. Bernstein generalized Pólya's theorem by weakening this gap condition. We give a simpler proof of Bernstein's theorem by applying a recent generalization of Ingham's theorem. Furthermore, we also solve a simultaneous observability problem by using this theory.     

推荐系统研究进展

推荐系统（recommender system,RS）是当今网络时代的产物,在技术研究和应用方面取得了很多成果。综述了推荐系统领域的研究状况和进展,提出了3个研究阶段,并指出了每个阶段标志性意义的事件。在当前大数据环境下,从数据的角度看推荐,提出了推荐系统新的分类方法,即根据推荐时所使用的数据不同分为7种类别,同时指出了每个类别使用了哪些推荐模型及其优缺点。提出了在大数据环境下进行推荐是未来推荐系统研究的一个大方向,分析了推荐视角下的大数据机制。最后比较和总结了推荐系统的评价指标,给出了未来的主要研究方向和可能的突破点。     

Serious Games: Broadening Games Impact Beyond Entertainment

Computer and videogames for many years has been an island of technology and design innovation largely left to itself as it morphed from a cottage business into a global media and software industry. While there have been pockets of derivative activity related to games and game technology only in the last half-dozen years has there been a real movement toward exploiting this industry in many new and exciting ways. Today the general use of games and game technologies for purposes beyond entertainment is collectively referred to as serious games. The Serious Games Initiative was formed in 2002 and since its inception has been among a number of critical efforts that has helped open up the world and many disciplines to the ideas and innovations that may be sourced from the commercial, independent, and academic game fields. This has been a person-by-person, project-by-project effort that not only has informed us about the potential of games but also in how you merge innovation and innovators from one discipline with those in another. In this talk we will explore the total gamut of the serious games field identifying past the obvious how games and game technologies are being applied to problems in a wide array of areas including healthcare, productivity, visualization, science, and of course training and education. Once a proper definition of serious games is established the talk will focus on the current state of the field as it relates to research and infrastructure issues that are needed to make the difference between seeing serious games take hold as a major new practice or having it devolve into another trend of the moment lost to history.     

Designing Then and Now

Over the past 25 years, we've made great advances in tooling, technologies, and techniques that make software design more concrete. But design still requires careful thought.     

Innovating then and Now

Steven Alter. the Work System Method: Combining People, Processes, and IT for Business Results. Larkspur, CA: Work System Press, 2006, 280 pp.

Stanley Bing. Rome Inc.: the Rise and Fall of the First Multinational Corporation. New York: W.W. Norton & Co., 2006, 197 pp.

Victor Fey and Eugene Rivin. Innovation on Demand: New Product Development Using TRIZ. Cambridge University Press, 2005, 242 pp.

Jay Liebowitz. Strategic Intelligence: Business Intelligence, Competitive Intelligence, and Knowledge Management. Boca Raton, FL: Auerbach Publications, 2006, 223 pp.     

Geogames: Designing Location-Based Games from Classic Board Games

The traditional image of interactive entertainment - games that reduce players' physical involvement to moving a joy stick - is obsolete. Games researchers and designers are already integrating complex movement into games. Location-based games involve body movements beyond figural space - that is, beyond the space of computer screens and small 3D objects. They focus on locomotion in vista space, typically a single room or sports field, or in environmental space, such as a neighborhood or city. Several location-based games have been designed for environmental space using localization technologies such as GPS. Some are adaptations of popular computer games, and others are rather straightforward chase games. A third type of game - what we call challenging location-based games - combines the intellectual and strategic appeal of classic board games with the real-time locomotion and physical involvement of location-based games. Furthermore, a straightforward approach to the spatial mapping of classic board games doesn't work. Instead, we developed the Geogames framework, which uses search techniques to identify a single temporal parameter for balancing sportive versus strategic elements     

How solved is the cost estimation problem?

Negotiations on project costs and delivery dates between the developers of software and the managers who request it are often difficult. The authors suggest an approach for establishing peace between software engineers and their customers. They argue that a few commonsense steps, coupled with historical data, can help every software team solve the cost estimation problem and, as a consequence, establish an environment in which both parties win     

Pushdown Processes: Games and Model-Checking

A pushdown game is a two player perfect information infinite game on a transition graph of a pushdown automaton. A winning condition in such a game is defined in terms of states appearing infinitely often in the play. It is shown that if there is a winning strategy in a pushdown game then there is a winning strategy realized by a pushdown automaton. An EXPTIME procedure for finding a winner in a pushdown game is presented. The procedure is then used to solve the model-checking problem for the pushdown processes and the propositional μ-calculus. The problem is shown to be DEXPTIME-complete.     

Computers and the future: Education

It is a pleasure to return to England to give this keynote address. During my stay as advisor to the National Development Programme in Computer Assisted Learning, I attended an early CAL meeting at Oxford; I met many of you and learned about ongoing projects. This trip renews many old acquaintances. Perhaps I haven't been in England frequently enough since then. The gentleman at Passport Control at Gatwick commented. “You have been neglecting us—you haven't been here since 1980”. I will try to do better in the future!This paper has four components. I begin with a series of assertions about computers in education, some supported later in the paper. I then review two examples of computers in education developed at the Educational Technology Center. A brief interlude considers the major advantages of the computer in learning. Finally I speculate on the future of the computer in education, arguing that it will be eventually the dominant delivery device for all areas of education. I consider aspects of what will happen.     

中国民间游戏和电子游戏的社会功能差异

游戏是一种古老的社会文化现象,自从有了人类就有了游戏。随着人类社会的发展、经济和科技水平的不断上升,游戏的概念和内涵也不再是跳皮筋、踢毽子等民间游戏活动。一种承载着更多经济、科技和文化内涵的游戏行为——电子游戏正在渗透到人们的生活中,人们认识到它更多的社会功能和价值,这种社会功能和价值因为游戏的内容、形式以及物质载体的巨大变化而形成了民间游戏和电子游戏的很大差异。     

Computing Now: Peer-Review Rigor Meets Social Networks

The IEEE Computer Society (CS) recently launched Computing Now (CN; http://computingnow.computer.org), a single portal for all 14 CS magazines, that attempts to expose the traditional peer-reviewed content in CS magazines to a more collaborative style of social networks and Web 2.0. CN hopes to build a Web site that merges all the tradition and rigor of peer reviewing with social networks' scale and dynamics.     

Simple Stochastic Games,Parity Games,Mean Payoff Games and Discounted Payoff Games Are All LP-Type Problems

We show that a Simple Stochastic Game (SSG) can be formulated as an LP-type problem. Using this formulation, and the known algorithm of Sharir and Welzl [SW] for LP-type problems, we obtain the first strongly subexponential solution for SSGs (a strongly subexponential algorithm has only been known for binary SSGs [L]). Using known reductions between various games, we achieve the first strongly subexponential solutions for Discounted and Mean Payoff Games. We also give alternative simple proofs for the best known upper bounds for Parity Games and binary SSGs. To the best of our knowledge, the LP-type framework has been used so far only in order to yield linear or close to linear time algorithms for various problems in computational geometry and location theory. Our approach demonstrates the applicability of the LP-type framework in other fields, and for achieving subexponential algorithms.     

Learning in cyberspace:shaping the future

Proponents of multimedia and Internet based educational tools have long claimed their potential, but the absence of broad based quantitative research from controlled experimental use, continues to mitigate the transfer of that potential to reality. This paper reports on experimental work in Singapore, which was designed to establish a supportable theoretical foundation for the hypothesis that the use of information technology (IT) resources in education, does improve pedagogic outcomes. The authors reach a positive conclusion, and attribute those improved outcomes to the use of IT resources through the conduit of improved student motivation. The paper also draws the important distinction between using multimedia and the Internet as a facilitator of learning rather than teaching, and reports upon the research project in detail, particularly improvements in student understanding and results, quantified at 11% in one semester. There were also productivity gains of 16% for educators as a result of effective use of Internet resources and use of the Internet to deliver course material for learning. Based on the research work done, this paper draws the statistically valid conclusion that use of IT resources does improve student learning.