The article by Robert W. Floyd in the March 1960 issue described an algorithm for determining whether a given symbol string is a permissible ALGOL assignment statement. In his method Mr. Floyd replaces certain character pairs by single characters in an array until, in the well-formed formula, the character Σ is obtained. Although this method indeed determines formation legality, one must still analyze and delimit each constituent of the statement in order to reduce the problem language to a workable format.
This paper describes the use of simulation techniques at SDC in the analysis of time-sharing system operation. The purpose and goals of this research effort are briefly outlined and some comments on the advantages and disadvantages of direct simulation for this type of work are given. The existing simulator models are described in terms of inputs, general flow, and outputs; and the results of initial investigations with these models are given. Work currently in progress is discussed, and some related problems that may possibly be studied in the future by similar methods are noted.
Objective: Recent research by the authors has investigated alpha wave amplitude increases in response to reduced visual input as a system for controlling electrical devices, with application for the disabled. However, alpha wave changes contingent wi
People living with a severe disability suffer substantial personal and social consequences that reduce quality of life (QOL). One potential negative impact on the QOL of a disabled person is the loss of the ability to control devices in their immediate environment (such as the television, computer, telephones, lights, doors, etc.). Consequently, research and development has been conducted on technology designed to restore independence by providing some means of control over these devices. Technology that allows a severely disabled person to gain this type of control has been called an environmental control system (ECS). The aim of this review was to evaluate critically the status and efficacy of ECS technology for the severely disabled.To achieve this, a comprehensive database search was conducted for relevant material on technical and clinical aspects of ECS control.The review demonstrated that there is an abundance of work conducted on ECS technology, resulting in a number of creative control systems that are designed to be used by the severely disabled. These include switching systems that utilize voice, muscle, brain activity, head motion, eye blink, breath, chin, and so on. However, the review also established that rarely has the efficacy of these systems been scientifically established.Severely disabled persons need access to ECS technology that has been shown to be efficacious. While the severely disabled gain benefits from using ECS technology, challenges still exist before ECS technology for the severely disabled can provide highly reliable and user-friendly device control.
Recent work indicates that the variation in the occipital alpha wave component of the EEG spectrum, controlled through eye closure, can be used by an untrained person to effect reliable activation of electrical devices. Here we describe and compare three real-time strategies, based on analogue and digital signal processing methods, of detecting the onset of alpha wave synchronization during eye closure. The goal of this work is to establish a method which satisfies the condition of rapid detection of alpha wave enhancement, thereby allowing for the efficient activation of devices, while simultaneously registering few or no false positives due to the natural variation in the alpha signal with eyes open. This work, based on measurements on 15 subjects in the age range 12 to 40 years, indicates that real-time analysis of the EEG power spectrum provides for rapid detection of the onset of alpha wave synchronization while maintaining low counts of false positives.
Recent research by the authors has resulted in the development of an environmental control system (ECS) that enables severely disabled persons to activate devices using their brain signals. This ECS has been called the Mind Switch and its effectiveness is based on alpha wave amplitude increases in response to reduced visual input (brief eye closure). Following extensive studies of the electroencephalograph (EEG) patterns of non-disabled and disabled people, as well as numerous trials of its efficacy, a third generation prototype has now been developed that is capable of being employed in the home environment. This paper describes in some detail this prototype. The information from this research will be used to optimize ECS technology designed for severely disabled persons to activate, quickly and remotely, electrical devices using their brain signals.
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