A FORTRAN program to compute vertical magnetic field of a horizontal rectangular loop on n-layered earth for em depth sounding

A FORTRAN program is described to compute the vertical magnetic field anywhere inside or outside a rectangular loop which carries a sinusoidally varying current and is horizontally placed on the surface of a n-layered earth. The program utilizes the concept of reciprocity and the known solution for a horizontal magnetic dipole source placed over a n-layered half-space. The computing algorithm is executable on a minicomputer like PDP 11/40 and as such is useful to many geoscientists who do not have access to mainframe computer, for computing model data to fit and interpret field observations from electromagnetic depth sounding experiments.     

Polyphonic Aspects of Software Process Looking for Philosophical Foundation of Software Engineering

This retrospective essay summarizes 50 years experience of a first-generation programmer in Japan focusing on his thoughts on software process issues. It started from strong concern of the structure of program execution processes inside computer hardware, then went out of digital box to think about software development and maintenance processes, namely how to deal with issues between people and software. Finally his main concern turned to the social issues of software evolution processes in the Internet society. The concept of "immaterial labor" seems to be important to think about today''s process issues outside of digital boxes.     

What makes good research in software engineering?

Physics, biology, and medicine have well-refined public explanations of their research processes. Even in simplified form, these provide guidance about what counts as “good research” both inside and outside the field. Software engineering has not yet explicitly identified and explained either our research processes or the ways we recognize excellent work. Science and engineering research fields can be characterized in terms of the kinds of questions they find worth investigating, the research methods they adopt, and the criteria by which they evaluate their results. I will present such a characterization for software engineering, showing the diversity of research strategies and the way they shift as ideas mature. Understanding these strategies should help software engineers design research plans and report the results clearly; it should also help explain the character of software engineering research to computer science at large and to other scientists. Published online: 13 June 2002     

Robotic Assembly Processes as a Driver in Architectural Design

Over the last couple of years industrial robots have increasingly gained the interest of architects and designers. Robotics in architecture and construction has mainly been looked at from an engineering perspective during the latter half of the twentieth century, with the main purpose of automating the building process. Today the focus has turned towards realizing non-standardized designs and developing custom fabrication processes. However, the specific characteristics of the robot, which distinguish it from common computer numerically controlled machines, are often overlooked. Industrial robots are universal fabrication machines that lend themselves especially well to assembly tasks. Applied to architecture this resolves to the ability to control and manipulate the building process. As such, applying industrial robots emphasizes construction as an integral part of architectural design. Moreover, designing and manipulating robotic assembly processes can become a driver in architectural design. The potential of such an approach is discussed on the basis of several design experiments that illustrate that by applying such methods, form is not derived from computation or geometry, but from a physical process.     

Analogy just looks like high level perception: why a domain-general approach to analogical mapping is right

Hofstadter and his colleagues have criticized current accounts of analogy, claiming that such accounts do not accurately capture interactions between processes of representation construction and processes of mapping. They suggest instead that analogy should be viewed as a form of high level perception that encompasses both representation building and mapping as indivisible operations within a single model. They argue specifically against SME, our model of analogical matching, on the grounds that it is modular, and offer instead programs such as Mitchell and Hofstadter's Copycat as examples of the high level perception approach. In this paper we argue against this positionon two grounds. First, we demonstrate that most of their specific arguments involving SME and Copycat are incorrect. Second, we argue that the claim that analogy is high-level perception, while in some ways an attractive metaphor, is too vague to be useful as a technical proposal. We focus on five issues: (1) how perceptionrelates to analogy,(2) how flexibilityarises in analogicalprocessing, (3) whether analogy is a domain-general process, (4) how micro-worlds should be used in the study of analogy, and (5) how best to assess the psychological plausibility of a model of analogy. We illustrate our discussion with examples taken from computer models embodying both views.     

A computer support tool for the early stages of architectural design

Even in the current computer age, there are still many important application areas, such as early architectural design, where traditional tools like sketching on paper continue to be preferred by many professionals over computer-based tools. There is a growing awareness that there are often very good grounds for this preference. Hence, instead of trying to replace such traditional ways of working, it is now often considered more opportune to try and preserve the strengths of these traditional ways of working, while at the same time improving them by providing access to new media. This is one of the main objectives of the augmented reality approach that we adopt here. In this paper, we specifically discuss the realization of a tool for early architectural design on an existing augmented reality system, called the Visual Interaction Platform. We describe the development process, the resulting tool and its performance for elementary tasks such as positioning and overdrawing. We also identify directions for future research and applications.     

Retrovirus-based computer

A practical intra-cellular biomolecular computer should work inside living cells without damaging them. The retrovirus-based biomolecular computer has been designed, by mimicking the natural processes of living cells, to enable the creation of a practical intra-cellular computer. Here, I review the idea of retrovirus-based computing, and examine its feasibility. This idea might lead to the development of new technologies not only for biological research, but also for medical purposes. In future, through the development of the in vivo retrovirus-based computer, gene diagnosis and gene therapy is expected to cooperatively work inside living cells, enabling intelligent gene therapy technology that uses biomolecular computing.     

Through the looking glass: why no wonderland: Computer applications to architecture in the USA

The work in computer-aided architectural design in the USA is a natural outgrowth of the situation. Without prefabricated building systems, large integrated c.a.a.d. systems are not likely to come about quickly. However, work on the the development of briefs and the organization of design information is a natural and equally important application.Architectural applications have not received large amounts of research support in relation to other fields and thus computer scientists and other outside researchers have not been encouraged to consider architectural problems. The consequences have been that results have not been quick in coming, but the few architectural researchers working in this area have been able to obtain modest funding. The direction of these efforts has been laissez faire. Technical know-how is quite sophisticated in the universities and some firms. Many programs utilize list processing techniques, dynamic storage allocation, and special interpreters.With no crises or new priorities on the horizon that will change the situation, larger scale investment by government in c.a.a.d. research will require that the researchers justify the value of this line of work. Applications will continue to come about only if the benefits resulting from them are fairly obvious. In the meantime, there is freedom within the universities to explore radical approaches for the application of computers to architecture.     

Extraction of salient contours from cluttered scenes

The responses of neurons in the primary visual cortex (V1) to stimulus inside the receptive field (RF) can be markedly modulated by stimuli outside the classical receptive field. The modulation, relying on contextual configurations, yields excitatory and inhibitory activities. The V1 neurons compose a functional network by lateral interactions and accomplish specific visual tasks in a dynamic and flexible fashion. Well-organized structures and conspicuous image locations are more salient and thus can pop out perceptually from the background. The excitatory and inhibitory activities give different visual physiological interpretations to the two kinds of saliencies.A model of contour extraction, inspired by visual cortical mechanisms of perceptual grouping, is presented. We unify the dual processes of spatial facilitation and surround inhibition to extract salient contours from complex scenes, and in this way coherent spatial configurations and region boundaries could stand out from their surround. The proposed method can selectively retain object contours, and meanwhile can dramatically reduce non-meaningful elements resulting from a texture background. This work gives a clear understanding for the roles of the inhibition and facilitation in grouping, and provides a biologically motivated computational strategy for contour extraction in computer vision.     

The geography of the digital divide: broadband deployment in the Community of Madrid

Realising the potential of the information society requires an adequate broadband infrastructure, a sine qua non condition for usage. The different deployment rhythms of broadband networks threaten to increase the distance separating developed and developing countries. However, inside developed countries, separating lines are also being traced on regional or local scales. The magnitude and characteristics of this second form of geographic digital divide are not thoroughly known. This article provides this analysis for a specific case, namely the Community of Madrid. We conclude that outside the metropolitan areas, adapting existing infrastructures, instead of deploying new networks, is the actual base for expanding broadband accessibility. However, it seems certain that the deployment is quite far from being universal, at least in the medium term. Population size seems to be the most relevant criterion for identifying threatened areas.     

Living cell as a universal computer

A number of similarities between living cells and universal computers are considered. Intracellular life processes are compared to computation processes inside a computer. Proteins coordinating intracellular processes are associated with computer programs during runtime. The possibility of the existence of a genetic programming language that allows effectively building new genes from the existing ones is considered.     

Linear minimum mean square error estimation for discrete-timeMarkovian jump linear systems

The linear minimum mean square error estimator (LMMSE) for discrete-time linear systems subject to abrupt changes in the parameters modeled by a Markov chain &thetas;(k)ϵ{1...,N} is considered. The filter equations are derived from geometric arguments in a recursive form, resulting in an on-line algorithm suitable for computer implementation. The author's approach is based on estimating x(k)1/sub {&thetas;(k/=i}) instead of estimating directly x(k). The uncertainty introduced by the Markovian jumps increases the dimension of the filter to N(n+1), where n is the dimension of the state variable. An example where the dimension of the filter can be reduced to n is presented, as well as a numerical comparison with the IMM filter     

Vibrating tectonics: gestural trajectories,energy mappings and self-conditioning design strategies

The transposition from painting to architecture from two-dimensional entity to a spatial structure, became the core idea of a project designed for the students of architecture to encourage them to examine the possibilities of abstract expression in the conceptualisation of architectural ideas and strategies. A series of tasks were created to enable them to identify full expression and physical presence of movement in an abstract painting as transferable into architecture. There were then other tasks oriented towards discovering, investigating and recording various types of spatial conditions as potentially architectural. Fundamental issues related to Jackson Pollock's philosophy of painting are now finding a new dimension in the digital domain of 3D modelling techniques, supplying them with the tool capable of not only projecting the release of pure energy in virtual space but also of recording endless sequences of free gestures in time and space. These can then be rewritten in the form of a computer program as well as being controlled on a higher level of architectural design.     

Mirage+: A kernel implementation of distributed shared memory on a network of personal computers

We describe the evolution of a distributed shared memory (DSM) system, Mirage, and the difficulties encountered when moving the system from a Unix-based* kernel on the VAX to a Unix-based kernel on personal computers. Mirage provides a network transparent form of shared memory for a loosely coupled environment. The system hides network boundaries for processes that are accessing shared memory and is upward compatible with the Unix System V Interface Definition. This paper addresses the architectural dependencies in the design of the system and evaluates performance of the implementation. The new version, MIRAGE +, performs well compared to Mirage even though eight times the amount of data is sent on each page fault because of the larger page size used in the implementation. We show that performance of systems with a large page size to network packet size can be dramatically improved on conventional hardware by applying three well-known techniques: packet blasting, compression, and running at interrupt level. The measured time for a page fault in MIRAGE + has been reduced 37 per cent by sending a page using packet blasting instead of using a handshake for each portion of the page. When compression was added to MIRAGE +, the time to fault a page across the network was further improved by 47 per cent when the page was compressed into one network packet. Our measured performance compares favorably with the amount of time it takes to fault a page from disk. Lastly, running at interrupt level may improve performance 16 per cent when faulting pages without compression.     

Secrecy and group creation

We add an operation of group creation to the typed π-calculus, where a group is a type for channels. Creation of fresh groups has the effect of statically preventing certain communications, and can block the accidental or malicious leakage of secrets. Intuitively, no channel belonging to a fresh group can be received by processes outside the initial scope of the group, even if those processes are untyped. We formalize this intuition by adapting a notion of secrecy introduced by Abadi, and proving a preservation of secrecy property.     

Hindu temples: Models of a fractal universe

Hindu philosophy views the cosmos to be holonomic and self-similar in nature. According to ancient architectural tradition, Hindu temples are symbols of models of the cosmos and their form represents the cosmos symbolically.The procedures and methods used in the construction of Hindu temples bear a striking resemblance to the procedures of computer graphics, including discretization, fractalization and extensive use of recursive procedures, including self-similar iteration. The instructions given in ancient Vastu shastras (texts on architecture) work like general programmes to generate various types of temples.The paper is an attempt to draw attention to the similarities between the procedures and resulting forms in computer graphics and Hindu temple architecture and to explain the relationship that exists between the form of the temple and the concepts of Hindu philosophy. It is proposed that Hindu temples may be viewed as threedimensional fractal models and that the use of fractal geometry procedures has a special symbolic meaning in the generation of the forms of Hindu temples.     

Reliable election in broadcast networks

Election in a computer network is an operation in which one process is selected from among a group of processes to perform a particular task. An election is characterized by (1) the capacities of the candidates, and (2) the agreement reached by all processes to elect the master. In this paper, we show that election is in fact a very general style of computation. Many problems in computer networks can be solved by means of election. We then examine the election problem in computer networks with broadcast support. Basic design issues of election algorithms are addressed, and a number of election algorithms are presented based on various environments. These algorithms allow all nonfaulty processes to elect one and only one process as the master, and, by changing the definition of the capacities, they can be applied to a variety of problems.     

改进的基于欧氏距离测度网格模型体素化算法

在基于到网格多边形表面的法矢量函数作为距离标准的体素化算法的基础上，提出以多边形面的最小包围盒作为计算单元，以欧式距离作为测度实现网格模型的体素化，极大地提高了计算速度，使得只能在图形工作站上实现的算法在微机平台上得以实现．针对通常采用Flooding操作判断内外体素、但应用于存在封闭空腔的模型时将会产生错误的情况，设计了一种根据体素标志位序列判断内外体素的算法．     

A geometric modelling framework for conceptual structural design from early digital architectural models

Computer support for conceptual structural design is still ineffective. This is due, in part, to the fact that current computer applications do not recognize that structural design and architectural design are highly interdependent processes, particularly at the early stages. The goal of this research is to assist structural engineers at the conceptual stage with early digital architectural models. This paper presents a geometric modeling framework for facilitating the engineers’ interactions with architectural models in order to detect potential structural problems, uncover opportunities, respect constraints, and ultimately synthesize structural solutions interactively with architectural models. It consists of a process model, a representation model and synthesis algorithms to assist the engineer on demand at different stages of the design process. The process model follows a top-down approach for design refinements. The representation model describes the structural system as a hierarchy of entities with architectural counterparts. The algorithms rely on geometric and topologic relationships between entities in the architectural model and a partial structural model to help advance the synthesis process. A prototype system called StAr (Structure-Architecture) implements this framework. A case study illustrates how the framework can be used to support the conceptual structural design process.     

Method for Calculation of Sky Light Luminance Aiming at an Interactive Architectural Design

Recently, computer graphics are frequently used for both architectural design and visual environmental assessment. Using computer graphics, designers can easily compare the effect of the natural light on their architectural designs under various conditions, such as different times of day, seasons, atmospheric conditions (clear or overcast sky) or building wall materials. In traditional methods of calculating the luminance due to sky light, however, all calculation must be performed from scratch if such conditions undergo change. Therefore, to compare the architectural designs under different conditions, a great deal of time has to be spent on generating the images. This paper proposes a new method of quickly generating images of an outdoor scene, taking into account glossy specular reflection, even if such conditions change. In this method, luminance due to sky light is expressed by a series of basis functions, and basis luminances corresponding to each basis function are precalculated and stored in a compressed form in the preprocess. Once the basis luminances are calculated, the luminance due to sky light can be quickly calculated by the weighted sum of the basis luminances. Several examples of an architectural design demonstrate the usefulness of the proposed method.