NPSNET-V. A new beginning for dynamically extensible virtualenvironments

At the Naval Postgraduate School (NPS) we, like others in the collaborative VE community, have extolled the virtues of persistent online virtual worlds for years. We previously addressed the infrastructure requirements of a large-scale, persistent online virtual world: runtime extensibility of both content and applications; scalability in world complexity and number of participants; and composability of heterogeneous content and applications. We follow those arguments with the first publication describing NPSNET-V     

新年伊始 TI加强C2000系列在PLC领域实力 TMS320F2806x Piccolo MCU能为可再生能源、PLC与电机控制提供浮点内核

<正>15年以来,德州仪器(TI)面向工业应用的C2000系列一直在电机、数字马达控制等实时控制领域贡献着自己的力量。TI的高性能浮点微控制器(MCU)Delfino系列(运算速度约在100～300 MIPS)及低端的Piccolo MCU系列(运算速度在40～60MIPS)覆盖的范围虽然很广,但是缺少运算速度在60～80 MIPS之间的实时处理MCU,为了弥补这一空缺,TI日前宣布推出15款最新低成本TMS320F2806x Piccolo浮点MCU,以提供能平衡低成本Piccolo与高性能Delfino的性能,为可再生能源、电力线通信(PLC)、电机控制、数字电源控制等提供浮点内核。     

A comparison of single- and dual-task measures to predict simulator performance of beginning student pilots

An experiment comparing the predictive validity of single- versus dual-task measures is reported. Two identical one-dimensional tracking tasks were used in the experiment. One task was controlled by the subject's left hand and the other by his right. Fifty-seven men first received two trials on each of the tasks alone followed by 25 dual-task trials. Finally, they again performed each task alone for one trial. The subjects subsequently worked through a short basic flight course consisting of ground instruction and practice in a GAT-2 simulator. After completing the course, the subjects performances on four level turns, four descents, and four descents followed by stalls were scored. Performance in the simulator was correlated with performance on each tracking trial. The predictive validity of the early single-task scores decreased with practice while the dual-task validity increased throughout the testing session. However, the predictive validity of the late single-task scores was almost as large as that of the late dual-task scores. Several analyses indicated that late single-task performance was more similar to late dual-task performance than to early single-task performance. A control theory analysis of the data revealed that a dual-task control strategy had been employed in the late single-task trials and probably accounted for the comparable predictive validities of late single-and dual-task scores.     

青啤分销从SCM入手实现战略转型

青岛啤酒股份有限公司是国家特大型企业,其前身是国营青岛啤酒厂,始建于1903年,是中国历史最悠久的啤酒生产企业。青啤是一个典型的依靠质量和销售制胜,将销售渠道管理作为核心能力之一的企业,其采用多级     

A new structure-from-motion ambiguity

Demonstrates the existence of an approximate, intrinsic ambiguity in Euclidean structure from motion (SFM) which occurs as generically as the bas-relief ambiguity but, unlike it, strengthens for scenes with more depth variation. The ambiguity does not occur in projective SFM, but the reasons for this make projective reconstructions more likely to have large errors. Our analysis gives a semiquantitative characterization of the least-squares error surface over a domain complementary to that analyzed by Jepson, Heeger, and Maybank. As part of our analysis, we show that the least-squares error for infinitesimal motion-the optical-flow error-gives a good approximation to the least-squares error for moderate finite motions. We propose that many high-error local minima occur for epipoles in or near the image. We also establish the existence of a new local minimum in minimizing over the rotation, given the translation direction     

A new controllability condition

A controllability condition for a constant linear systemdot{x}= Ax + Buis given in terms of the minimum polynomials ofAand of the columns ofB. An application is made to canonical forms.     

A new grammar checker

CorrecText, from Houghton-Mifflin, is a significant advance in grammar checkers, because it uses a full parse of sentences in its analysis. Though limited by the fact that many English sentences are syntactically ambiguous, the program can find many errors in grammar, style, and usage. Still, questions remain about where and how it can be useful. It is not terribly useful on final versions of good prose; the makers assert that it is more useful on unedited prose, where there are many inadvertent errors. An empirical study of much unedited prose would not only verify this assertion, but would help improve the program. David N. Dobrin has run a consulting firm, Lexicom, since 1985, and specializes in software, software manuals and warning labels. He was formerly Assistant Professor of Technical Communication at the Massachusetts Institute of Technology. He has written numerous articles on computers and writing, and his book, Writing and Technique, has been published by the National Council of Teachers of English.     

A new grammar checker

CorrecText, from Houghton-Mifflin, is a significant advance in grammar checkers, because it uses a full parse of sentences in its analysis. Though limited by the fact that many English sentences are syntactically ambiguous, the program can find many errors in grammar, style, and usage. Still, questions remain about where and how it can be useful. It is not terribly useful on final versions of good prose; the makers assert that it is more useful on unedited prose, where there are many inadvertent errors. An empirical study of much unedited prose would not only verify this assertion, but would help improve the program.