Numerical Methods with Adaptive Artificial Viscosity for Solving Navier−Stokes Equations

A numerical method for solving two-dimensional problems of a viscous compressible gas based on Navier–Stokes equations with the introduction of adaptive artificial viscosity is presented. The proposed method is implemented for areas of the general form on triangular grids. The method of the adaptive artificial viscosity is taken as the basis of the proposed numerical method and ensures the monotonicity of the solutions, even in the presence of shock waves. The artificial viscosity (introduced into the difference scheme) is constructed in such a way that it is absent in the boundary layer where the dynamic viscosity acts. The viscosity is determined from the conditions of the fulfillment of the maximum principle. The series of calculations of an external flow around a cylinder for various Reynolds and Mach numbers is described.     

The complexity of the temporal logic with “until” over general linear time

It is shown that the decision problem for the temporal logic with the strict until operator over general linear time is PSPACE-complete. This shows that it is no harder to reason with arbitrary linear orderings than with discrete linear time temporal logics. New techniques are used to give a PSPACE procedure for the logic.     

The “explicit-implicit” distinction

Much of traditional AI exemplifies the explicit representation paradigm, and during the late 1980's a heated debate arose between the classical and connectionist camps as to whether beliefs and rules receive an explicit or implicit representation in human cognition. In a recent paper, Kirsh (1990) questions the coherence of the fundamental distinction underlying this debate. He argues that our basic intuitions concerning explicit and implicit representations are not only confused but inconsistent. Ultimately, Kirsh proposes a new formulation of the distinction, based upon the criterion ofconstant time processing.The present paper examines Kirsh's claims. It is argued that Kirsh fails to demonstrate that our usage of explicit and implicit is seriously confused or inconsistent. Furthermore, it is argued that Kirsh's new formulation of the explicit-implicit distinction is excessively stringent, in that it banishes virtually all sentences of natural language from the realm of explicit representation. By contrast, the present paper proposes definitions for explicit and implicit which preserve most of our strong intuitions concerning straightforward uses of these terms. It is also argued that the distinction delineated here sustains the meaningfulness of the abovementioned debate between classicists and connectionists.     

The specification of “specification”

The notion of specification plays a key role in the developing science of computing. It is typically considered to be the keystone in the software development process. However, there is no single, generally agreed meaning of specification that bears close scrutiny. Instead there is a variety of different, although partially interlocking and overlapping interpretations of the term.We catalogue this varietal profusion and attempt to lay bare both the sources and consequences of each major alternative. We attempt to present the full range of possibilities, and the biases inherent in each style of interpretation.We believe that there is a pressing need for clarification of the meaning of specification (and several other important terms), especially in view of the fact that so many practitioners and theoreticians assume, erroneously, that a clear meaning already exists (even though they might disagree as to what it is). In particular, we feel that a more general awareness of the difficulties that currently attach to this key concept may go some way towards bridging (if not actually healing) the rift that currently exists between the engineering and scientific aspects of computing.The most deadly thing in software is the concept ... that you are going to specify what you are going to do, and then do it. And that this is where most of our troubles come from. Ross, Garmisch.What happens is that specifications of software are regarded as functional specifications ... It is my belief that anybody who is responsible for the implementation of a piece of software ... must specify the design, the form. Sharp, Rome.No matter how precisely you try to specify a system, once you have built it you find it isn't exactly what is wanted. Oestreicher, Rome.... the admission of shortcomings is the primary condition for improvement. Dijkstra, Garmisch.     

The Professor Doth Protest Too Much, Methinks: Problems with the Foster ”Response“

In Response to Elliott and Valenza, 'And Then There Were None', (1996) Donald Foster has taken strenuous issue with our Shakespeare Clinic's final report, which concluded that none of the testable Shakespeare claimants, and none of the Shakespeare Apocrypha poems and plays – including Funeral Elegy by W.S. – match Shakespeare. Though he seems to accept most of our exclusions – notably excepting those of the Elegy and A Lover's Complaint – he believes that our methodology is nonetheless fatally flawed by worthless figures ... wrong more often than right, rigorous cherry–picking, playing with a stacked deck, and conveniently exil[ing] ... inconvenient data. He describes our tests as foul vapor and methodological madness.We believe that this criticism is seriously overdrawn, and that our tests and conclusions have emerged essentially intact. By our count, he claims to have found 21 errors of consequence in our report. Only five of these claims, all trivial, have any validity at all. If fully proved, they might call for some cautions and slight refinements for five of our 54 tests, but in no case would they come close to invalidating the questioned test. The remaining 49 tests are wholly intact. Total erosion of our findings from the Foster critique could amount, at most, to half of one percent. None of his accusations of cherry–picking, deck–stacking, and evidence–ignoring are substantiated.     

Language authoring with “comet”

Conclusion From the language teacher's point of view, authoring languages and systems have always had two major drawbacks: flexibility and simplicity of use seemed to exclude each other, and features specific to language instruction were not included in the design. COMET's template collection with its variants for individual languages attempts to deal with these problems. The present package of highutility programs has proven its worth in a university context by making it possible to create-full-year language courses at relatively modest cost. Since a lesson of five exercises, containing from 10 to 20 questions each, can be input by a careful typist in one working day, the term development has once again become synonymous with the creative process of designing pedagogic material.Future work will concentrate on incorporating user suggestions for improvement and creating new, specialized patterns to enhance the methodological versatility of the system.Wolfram Burghardt, an associate professor of modern languages and literatures of the University of Western Ontario, has developed print, audio and computer-based courses.     

Collaborative Research Centre “Situated Artificial Communicators” at the University of Bielefeld, Germany

The Collaborative Research Centre Situated Artificial Communicators (SFB 360) is employed in modelling that which a person performs when, with a partner, he cooperatively solves a simple assembly task in a certain situation. Acoustic perception of the spoken word, visual perception of the partner and the objects and processes involved in the situation, understanding of that perceived, the formulation of own utterances, e.g. instructions to the partner, and the planning and performance of actions belong to these intelligence abilities. The theme of the Collaborative Research Centre SFB 360, in which Linguistics, Cognitive Science and Artificial Intelligence are closely entwined, is unique in this form. The scientific headquarters at the University of Bielefeld, in North Rhine Westphalia, Germany, has succeeded in entering a field of research which, in the trend of the growing importance of intelligent information systems, is a decisive factor for technical innovation.     

The “presence of others” in a virtual environment: different collaborative modalities with hybrid resources

The purpose of this study is to see in which forms and under which conditions social presence turns into collaboration. Eight couples were asked to find some objects in a virtual environment in which collaboration was allowed but not mandatory. The qualitative analysis of the video recordings shows that all participants resorted to collaboration in forms that were justified by the requirements of the task, the environmental affordances and the different expertise.

The metamorphoses of the “Exemplar”

The starting point of this work isthe artificial, as defined in a previous study by Massimo Negrotti and, more completely, in the essay presented here, as a machine which reproduces the essential performance of some natural subsystem that serves as an exemplar, at a chosen level of observation. I assume also Negrotti's distinction between the technology of the artificial and conventional technology. These theoretic assumptions, and the relevant terminology, represent here the starting point for a reflection upon the process of imitating the natural exemplar and ofideating the technological object, and upon the interrelations between these two moments of inventiveness.     

The role of “craft language” in learning “Waza”

The role of craft language in the process of teaching (learning) Waza (skill) will be discussed from the perspective of human intelligence.It may be said that the ultimate goal of learning Waza in any Japanese traditional performance is not the perfect reproduction of the teaching (learning) process of Waza. In fact, a special metaphorical language (craft language) is used, which has the effect of encouraging the learner to activate his creative imagination. It is through this activity that the he learns his own habitus (Kata).It is suggested that, in considering the difference of function between natural human intelligence and artificial intelligence, attention should be paid to the imaginative activity of the learner as being an essential factor for mastering Kata.This article is a modified English version of Chapter 5 of my bookWaza kara shiru (Learning from Skill), Tokyo University Press, 1987, pp. 93–105.     

The “smart camera” adaptive optoelectronic complex

The “smart camera” is an adaptive optoelectronic complex applied for detection of car license plates. The complex consists of a digital camera with IR searchlight and IR filter joined with a PC compatible computation module. In the real-time mode, illumination of the license plates is analyzed in the pictures supplied from the camera, after which the camera parameters are changed to achieve optimal illumination of the car license plate. Vehicle number plates are also recognized in the smart camera itself. Video and results of detection are transferred by the network.     

Book Review on “The Knowledge Grid”

“Knowledge is power”, written by the English philosopher Francis Bacon in 1597, inspired a great rising in the human consciousness, opened the horizons for the human intelligence activities, and developed such a splendid world with a proliferation of knowledge that even Bacon could hardly imagine.     

The multi-facility location–allocation problem with polyhedral barriers

In this paper we consider the problem of locating N new facilities with respect to M existing facilities in the plane and in the presence of polyhedral barriers. We assume that a barrier is a region where neither facility location nor traveling is permitted. For the resulting multi-dimensional mixed-integer optimization problem two different alternate location and allocation procedures are developed. Numerical examples show the superiority of a joint treatment of all assignment variables, including those specifying the routes taken around the barrier polyhedra, over a separate iterative solution of the assignment problem and the single-facility location problems in the presence of barriers.     

The new ipad “屏”什么火？

上月，当互联网发布2012年最新的中国平板电脑市场分析月报时．我们惊奇地发现，因乔老爷的死而备受世人关注的The new ipad （以下简称“iPad3）．如今只剩下了—“关注”二宇。……为什么堪称乔布斯遗作的神器．会论为大家“眼中的好东西“，而无法吸引更多人去疯狂购买呢？     

The Fall of “Adams’ Thesis”?

The so-called ‘Adams’ Thesis’ is often understood as the claim that the assertibility of an indicative conditional equals the corresponding conditional probability—schematically:

玩转“牛排” The new iPad完全攻略

苹果在今年3月7日正式发布了第三代iPad产品,这款产品被命名为The new iPad(以下简称"新iPad")。它拥有一块1536×2048的巨型视网膜屏,并配备了一个采用背光成像技术的后置500万像素iSight摄像头。它还配备了一颗A5X四核处理器,同时内存容量也首次提升到了1GB。那么,新iPad在这一系列的升级之后,给我们带来了什么新的体验与用途呢?