EDIT—an interactive network service; design and implementation

EDIT is a time-sharing system which offers interactive services over the NPL network. These services include various kinds of editing, word processing, data movement and file control. The system is implemented on a PDP11/40 and can serve up to 30 users simultaneously, on high-speed displays and other terminals. There is an attached background processor (PDP11/45) which supports graphics and background jobs. This paper describes the design and implementation of EDIT and relates this to the needs of the system and of its users.     

An interactive computer graphics approach to the design of marching band routines

The availability of inexpensive minicomputers and low cost digital/analog conversion equipment enables one to use interactive graphics in situations where such techniques were previously infeasible. The University of Tulsa is presently developing an interactive graphics package entitled BANDMARCH to assist the choreography of marching band drills. The graphics hardward consist of a 32K Interdata Model 70 minicomputer, a 5MB Diablo Disc system, a Tektronix 603 monitor with 256 × 256 point display provided by a pair of Detel 8 bit D/A converters. The program enables a band director who is most likely not computer oriented to prepare a routine in an existing language (About Face, Left Flank) and view the result of his ‘design’ in real time. The obvious interactive features of editing, cataloguing and accessing standard functions must be provided in a way that can be easily understood.

T.U.'s BANDMARCH (not an acromym) provides such features. Common data structures in a relatively novel environment are a demonstration of the soundness of these techniques to an interactive graphics situation.     

Transportation interface facilities design using interactive high-level computer graphics

A prototype pedestrian facilities design system is described. The design system exploits the capabilities of an intelligent high-resolution vector graphics workstation which features a highly interactive computer graphics environment. A summary of historical developments in pedestrian facility design and graphics workstation architecture is presented, followed by a discussion of the stochastic model and interactive computer graphics features utilized by a prototype facilities design system. Potential applications of such a design system are discussed, and promising areas of future development are outlined.     

A new computer graphics approach to parameter space design of control systems

This paper presents a new approach to parameter space design of linear multivariable control systems. The complete solution of a pole region assignment problem for single-input systems is obtained as an admissible region in then-dimensional parameter space of state feedback gains. We develop a new modeling technique for these admissible parameter space regions which is superior to previous ones because it permits unambiguous and efficient graphical display of slices in 2D and 3D subspaces. In an interactive computer graphics implementation, this method provides an environment where the influence of stability, performance, robustness, integrity, and control constraints on design parameters can be directly visualized and complex tradeoffs are resolved in an interactive way. By judicious combination of overlays, color, and/ or animation, admissible ranges of up to five or six design parameters can be displayed simultaneously. A sequential decomposition technique which selects slices for full parameter space design of lower dimensional subsystems such that the remaining eigenvalues are invariant is used for systems of arbitrarily high order. Parameter space design of unity rank feedback for multiinput systems is done in exactly the same fashion, while systematic sequential design of full rank feedback is achieved as the sum of dyadic stages to which the single-input modeling techniques apply. Examples are given for all presented methods to show the flexibility and potential as a computer-aided control system design framework with a novel integration of computer graphics technology.     

An interactive approach to facilities design using microcomputers

Facilities design is an industrial engineering activity which can benefit greatly from a methodology which effectively combines the quantitative optimum seeking approach of computer implemented algorithmic techniques and the creativity and perception of the human designer. FLING (Facility Layout using INteractive Graphics) offers such an approach to facility design. Moreover, FLING is programmed in BASIC to run on the IBM-PC microcomputer (with 64K memory and a single disk drive). It makes full use of the personal computer color graphics. FLING is a highly interactive computer-assisted (not computer-generated) procedure which has clear advantages over manual techniques and eliminates the rework which is often necessary to make computer-generated layouts functional. This article describes the FLING program and its use. An illustrative example is given.     

Optimum design of reinforced concrete frames using interactive computer graphics

An integrated approach of the design and optimization problem of reinforced concrete frames, based on the use of interactive computer graphics is presented. The formulation of the optimization problem in terms of all the design variables and constraints is given. The size of the problem is greatly reduced if reinforcement areas are considered as dependent variables. A fully stressed design method is employed to optimize an automatically generated initial design. Analysis and design results plots, including complete reinforcement drawings, are available to designers, helping them to evaluate the current status of the design and allowing them to direct the entire computation process.     

A new algorithm for interactive graphics on multicomputers

As nonshared-memory multiple instruction, multiple data (MIMD) systems become more common, it becomes important to develop parallel rendering algorithms for them. These systems, known as multicomputers, can produce data sets so large that it is difficult to visualize the data on conventional graphics systems, especially if the visualization proceeds in tandem with the calculation. Parallel systems must run interactive graphics to allow convenient visualizations of their computations. While few parallel systems currently have a frame buffer that will support interactive rendering, such systems should be more common in the future. This article describes an algorithm suited for interactive polygon rendering, where the model's image on screen generally has frame-to-frame coherence. The algorithm uses this coherence to perform load-balancing calculations in parallel with the other calculations. The algorithm also uses an optimized version of personalized all-to-all communication, where all processors communicate with all other processors     

The application of interactive graphics to computer aided circuit design

When a computer is used in electric circuit design it forms part of an iterative loop and so the ergonomics of its input and output become of major importance. A circuit analysis program is described, which uses interactive graphics, and which was designed with particular attention given to ergonomics.     

An interactive example-driven approach to graphics recognition in engineering drawings

An interactive example-driven approach to graphics recognition in engineering drawings is proposed. The scenario is that the user first interactively provides an example of a graphic object; the system instantly learns its graphical knowledge and uses the acquired knowledge to recognize the same type of graphic objects. The proposed approach represents the graphical knowledge of an object in terms of its structural components and their syntactical relationships. We summarize four types of geometric constraints for knowledge representation, based on which we develop an algorithm for knowledge acquisition. Another algorithm for graphics recognition using the acquired graphical knowledge is also proposed, which is actually a sequential examination of these constraints. In the algorithm, we first guess the next component’s attributes (e.g., size, position and orientation) by reasoning from an earlier found component and the constraint between them, and then search for this hypothetical component in the drawing. If all of the hypothetical components are found, a graphic object of this type is recognized. For improving the system’s recognition accuracy, we develop a user feedback scheme, which can update the graphical knowledge from both positive (missing) and negative (mis-recognized) examples provided by the user for subsequent recognition. Experiments have shown that our proposed approach is both efficient and effective for recognizing various types of graphic objects in engineering drawings. This paper is an extension of our papers published in ICDAR2003 and GREC2003.     

An example of a pragmatic approach to portable interactive graphics

Standards for graphics subroutines would encourage the coding of portable programs using graphics. However such standards do not yet exist. In this paper a small set of generally available primitive subroutines, and fortran, are used to pragmatically provide a degree of portability for a second level graphics package. This package consists of only nine subroutines and yet provides considerable power for coding interactive graphical numerically oriented programs.     

一种新型的网络层心跳探测方案

针对路由器高可用性系统中心跳探测模块的常见问题,提出一套新型基于网络层自动调频的心跳探测方案。该方案采用双心跳线,结合动态调节探测周期的方法,并在网络层中实现。     

Optimal thresholding—A new approach

Finding the optimal threshold(s) for an image with a multimodal histogram is described in well-known literature as a problem in fitting a sum of Gaussians to the histogram. This fitting problem is shown experimentally to be a nonlinear minimization with local minima. A new minimization technique, tree annealing, is presented which finds the global minimum. Experimental results for histograms with two and three modes are presented.     

A new approach to input device key design using fingerprints

A new approach to designing input device keys is proposed, and a TV remote controller is used as an example to demonstrate the new approach for studying the relationship between fingerprints and key geometry. One hundred subjects' fingerprints of thumbs and index fingers of both hands were collected, and a computer program was used for converting the fingerprint to a bitmap form. Subsequently, the data were analysed to provide some guidelines for determining the key size and key shape for the input device. Finally, the fingerprints were used to study the pattern of finger press and the justification for keycap curvature for finger placement. The results showed that the new approach can be useful in guiding designers of input device keys. A further benefit of this study is in providing a more systematic approach with considerable general potential for studying input device keys.     

An unified approach for DTC design using interactive tools

This paper presents an interactive tool for dead-time compensator design. The tool is based on an unified dead-time compensator and considers models commonly used in industrial process control. The main contribution of this work is that the proposed tool and controller are simple to analyze and tune as they are based on an unique modified structure of the Smith predictor valid for every type of dead-time process (including integrating and unstable systems). Simple frequency analysis and block diagram transformations are used together with simulations to illustrate the main problems associated to the control of dead-time processes. Several examples of typical processes are presented to illustrate the fundamental concepts associated to the control of these systems. The interactive tool is not only useful for designing and analyzing but also for training and educational purposes.     

Learning to apply interactive graphics in computer-aided design — some UK user experience

Rapid diffusion of interactive graphics became possible in the UK in about 1978, when American CAD technology was marketed in ‘turnkey’ form. Interviews with CAD suppliers and 34 CAD users in the UK engineering industry yielded information about the learning processes which new users have to undergo. The different learning processes of operators and of managers are discussed, and conclusions are drawn about ways of easing the processes needed for the adaption of CAD.     

A new approach to the lattice Boltzmann method for graphics processing units

Emerging many-core processors, like CUDA capable nVidia GPUs, are promising platforms for regular parallel algorithms such as the Lattice Boltzmann Method (LBM). Since the global memory for graphic devices shows high latency and LBM is data intensive, the memory access pattern is an important issue for achieving good performances. Whenever possible, global memory loads and stores should be coalescent and aligned, but the propagation phase in LBM can lead to frequent misaligned memory accesses. Most previous CUDA implementations of 3D LBM addressed this problem by using low latency on chip shared memory. Instead of this, our CUDA implementation of LBM follows carefully chosen data transfer schemes in global memory. For the 3D lid-driven cavity test case, we obtained up to 86% of the global memory maximal throughput on nVidia’s GT200. We show that as a consequence highly efficient implementations of LBM on GPUs are possible, even for complex models.     

A new approach to variable-topology shape design using a constraint on perimeter

This paper introduces a method for variable-topology shape optimization of elastic structures called theperimeter method. An upper-bound constraint on the perimeter of the solid part of the structure ensures a well-posed design problem. The perimeter constraint allows the designer to control the number of holes in the optimal design and to establish their characteristic length scale. Finite element implementations generate practical designs that are convergent with respect to grid refinement. Thus, an arbitrary level of geometric resolution can be achieved, so single-step procedures for topology design and detailed shape design are possible. The perimeter method eliminates the need for relaxation, thereby circumventing many of the complexities and restrictions of other approaches to topology design.     

A broad and narrow approach to interactive evolutionary design—An aircraft design example

While interactive evolutionary computation (IEC) is starting to penetrate a larger scientific community, only few researchers have applied IEC to the design of complicated artifacts like machines or transportation systems. The present paper introduces a specific approach to interactive evolutionary computation that breaches the two historical categories of user-defined fitness and selection in each generation (narrow) and occasional user-intervention of an automated evolutionary process to correct the fitness function used for (multi-objective) optimization (broad). To highlight the approach, a real world aircraft design problem is employed that demonstrates the relevance and importance of both features for an effective design process.     

PIC — A language for typesetting graphics

PIC is a language for specifying pictures so that they can be typeset as an integral part of a document preparation system. The basic objects in PIC are boxes, lines, arrows, circles, ellipses, arcs and splines, which may be placed at positions specified absolutely or in terms of previous objects, and labeled with arbitrary text. The example below illustrates the general capabilities of the language. Most of the effort in designing PIC has gone into making it possible to specify the sizes and positions of objects with minimal use of absolute coordinates. This paper describes PIC, with primary emphasis on those aspects of the language that make it easy to use. The paper was typeset using PIC.