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Communications of the ACM

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ACM Forum


Computing perspectives: it's software now


Practical programmer: software teams

I have often heard the phrase, “We see what we know.” As technicians, we concentrate on technical ways to manage complexity: abstraction, design techniques, high-level languages, and so on. That is what we know best. But when …

Introduction—discrete event simulation

This special section deals with the simulation of complex systems, such as computer, communications, and manufacturing systems—specifically focusing on stochastic discrete event simulation. Such systems are typically (but not …

Parallel discrete event simulation

Parallel discrete event simulation (PDES), sometimes called distributed simulation, refers to the execution of a single discrete event simulation program on a parallel computer. PDES has attracted a considerable amount of interest …

Expert simulation for on-line scheduling

The state-of-the-art in manufacturing has moved toward flexibility, automation and integration. The efforts spent on bringing computer-integrated manufacturing (CIM) to plant floors have been motivated by the overall thrust to …

NEST: a network simulation and prototyping testbed

The Network Simulation Testbed (NEST) is a graphical environment for simulation and rapid-prototyping of distributed networked systems and protocols. Designers of distributed networked systems require the ability to study the …

Likelihood ratio gradient estimation for stochastic systems

Consider a computer system having a CPU that feeds jobs to two input/output (I/O) devices having different speeds. Let &thgr; be the fraction of jobs routed to the first I/O device, so that 1 - &thgr; is the fraction routed to the second …

Random numbers for simulation

In the mind of the average computer user, the problem of generating uniform variates by computer has been solved long ago. After all, every computer :system offers one or more function(s) to do so. Many software products, like …

Simulation of a semiconductor manufacturing line

Product turnaround time (TAT) is defined as the clock or elapsed time from wafer release to completed wafer fabrication. It is also known as cycle time, mean elapsed time, or manufacturing lead time. Turnaround time is arguably …

Traditional dialogue design applied to modern user interfaces

Several examples show that principles for the design of usable dialogues are just as important for modern graphical user interfaces as they are for traditional text-based interfaces.

Economic analysis of microcomputer hardware

Economic analysis of the hardware characteristics of the personal computer segment of the microcomputer market indicates that the variables that most affect cost are the bundle of attributes offered by the micros. Interestingly …

Inside risks: ghosts, mysteries and uncertainty

Background: Perhaps the most frustrating of all the Risks Forum cases are those in which uncertainty and doubts remain to spook us long after the event.