Browsing by Author "Graham, Martin"
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Item A breath by breath oxygen analyzer(1964) Moseley, Niles Ransom; Graham, MartinThis paper explains work done on the development of an instrument designed to determine the oxygen content of a sample of respiratory gas. The device relies on the fact that oxygen is paramagnetic and the other exhaled gases are not. The sample is passed through very small nonmagnetic tubes arranged in a bridge. At the application of a magnetic field to two opposite arms of the bridge, a pressure transducer placed across the bridge measures a pressure change that is entirely due to the oxygen in the sample.Item A capacitor buffer memory(1962) Schutz, Theodore Charles; Graham, Martin; Pfeiffer, Paul E.; Rorschach, Harold E., Jr.Digital information may be stored as a charge on a capacitor if suitable switches are used on the input and output lines. Characteristics of neon glow lamps (ionized from an external radio frequency source) pertinent to application in a capacitor store buffer memory were investigated. The results of this investigation and application of the results to the construction of a 64 bit buffer memory are discussed.Item A system for the display of the joint probability of occurrence of a pair of analog data(1964) Young, Joe Addison; Graham, MartinThis thesis proposes a system for recording three dimensional data which might be used to describe a joint probability distribution function. The proposed system is built around an Analab 1220 storage oscilloscope which uses a cathode ray tube with a potassium chloride screen. The optical density of the KC1 screen increases in a logarithmic fashion as a function of the time in which it is exposed to the 10 kv. electron beam of the cathode ray tube. Thus, if the screen has been calibrated, it should be possible to determine how long each part of the screen has been subjected to the influence of the electron beam simply by measuring the optical density of that particular area. The vertical and horizontal coordinates of a point on the screen represent two of the dimensions while the optical density at that point represents the third dimension. By using a closed circuit television camera to scan the illuminated surface of the KC1 screen, a signal proportional to the optical density of all parts of the screen might be Obtained which in turn could be used to produce a visual display of the three dimensional surface. This paper describes in some detail the behavior of the KC1 screen as it applies to the proposed system and compares it with the behavior of a photographic emulsion. A review is made of the various possible ways of scanning the KC1 screen and of the noise associated with each method. Because of the unstable nature of the alkali halide coloring under cathode ray bombardment, and because of the noise inherent in the scanning systems, it is concluded that the system will have only limited accuracy.Item Active filters for biological signal analysis(1966) Scoff, Robert John; Graham, MartinA way to handle biological signals by dividing the signals into bands in the frequency domain is the subject of this paper. Several filters were constructed and the results of a particular filter were analyzed. The problem of obtaining a constant power spectrum when a signal is divided into a number of bands by bandpass filters was investigated. This is very important in applications where it is desired to have all the components of an incoming signal weighted equally.Item An instantaneous respiratory tachometer(1964) Arthur, Randolph Martin; Graham, MartinThe development of an instrument which measures the rate of respiration from breath to breath is discussed. The device uses as its input the impedance change of the chest cavity associated with respiration. It is designed to be part of the Physiograph system. The tachometer contains a trigger which produces a set of pulses corresponding to the points of maximum inspiration. The pulses control circuitry which measures time between the pulses. The time measurement is converted to a measure of rate that is linear within 5% from 5 to 100 breaths per minute. Included is a discussion of the effect of component drift in the switching circuitry. Also described is a method of obtaining linearization of the rate with an RC integrator using a non-linear resistor. Finally, the trigger, which undergoes transition when the impedance signal moves a set amount from the relative maxima or minima, is discussed. Records of the tachometer operation in the Physiograph system are included.Item Analysis of medical waveforms(1964) Groves, Morton Dan Patrick; Graham, MartinA discussion of the necessity of automation of medical waveform analysis and of methods of performing this analysis is given as motivation for the project reported by this paper. This is followed by a short discussion of present methods which use either an analog or digital computer as a tool of analysis. Emphasis is placed on finding a better method of displaying the results of the analysis in some meaningful manner. The investigation of three proposed methods of using a large general-purpose digital computer to analyze medical waveforms and how each might give a useful display of the information contained in the waveform is reported. One method is selected for special discussion as to exactly how it might be implemented; reasons for selecting it over the other proposals are given. The selected method of analyzing medical waveforms (EEG in particular) and displaying the results involves performing a type of Fourier analysis on short sections of the waveform by using a special type of convolution and displaying the result on the cathode-ray display tube of the computer. Mathematical justification of the method of analysis is given. Such a system has been programmed and used on the Rice University Computer: actual procedures for use are discussed and special techniques which have been used are reported.Item Automating the verification of Boolean functions in digital computer logic modules(1966) Reese, Oran Thomas; Graham, MartinWhen digital computer logic modules contain a large number of gates and have many input and output terminals, the problem of testing the modules is a formidable one. This thesis is a study of one aspect of the problem, that being the verification of Boolean functions implemented by irredundant combinational logic. The assumption is made that even when an automatic testing system is employed it will not be feasible to provide all possible combinations of binary input signals as a test pattern sequence. The manner in which a module should be tested is influenced by a number of considerations. Several schemes are suggested for classifying modules according to the type of electronic hardware involved. For several circuit types, it is shown that the input bit patterns required for testing individual gates are independent of the type of circuitry. It is also shown, however, that when gates are interconnected on a module the type of circuitry as well as the interconnections must be considered. An algorithm is developed which produces a set of module input bit patterns that will detect any single gate failure and at least some double failures. The characteristics of an automatic testing system are considered, first by means of an abstract model and then with regard to actual equipment that can be adapted to the problem. Techniques for generating and manipulating bit patterns in the testing system are investigated. Finally, a number of suggestions are given for further investigation.Item Magnetic tape coder and decoder(1965) Kaplan, Chester; Graham, MartinThe need for the magnetic tape coder and decoder system and the requirements set forth for its operation are discussed. The coder output which is to be recorded serially on one channel of a frequency modulated tape recorder is in the form of four digit, binary-coded-decimal numbers in which the binary bit "0" is represented by a voltage level of +1 volt and the binary bit "1" is represented by +2 volts. The code word nuMbers are generated sequentially from the number 0 to the number 9999. When a code word number is to be sought at a later time in the decoding operation, the output of the tape recorder is connected to the input of the decoder and the tape is then searched. When the decoder senses the code word which is present on the dials of a Digiswitch, a relay is closed in order to perform other desired operations such as the copying of the data at any particular point of the original coded tape onto other tapes. A discussion of the system logic design is presented, followed by a discussion and analysis of the individual circuits, their waveforms, their interconnections, and their interactions with one another.Item Minimal minority logic synthesis of Boolean functions(1961) Johnson, Henry C., 1929-; Pfeiffer, Paul E.; Wilhort, J. C., Jr.; Graham, MartinItem Operation time monitor for a digital computer(1964) Tung, Chin; Graham, MartinThis paper is devoted to a detailed description of a device, an operation time monitor, which is used to investigate the behavior of the operation time in a digital computer. The principle employed to design the monitor is a very basic relation in fundamental electricity -the voltage across a capacitor is linearly proportional to the time during which a constant charging current is flowing through the capacitor. The constant current source which provides the required charging current is controlled by the pulses conveying the input information from a digital computer. Some data obtained by this monitor are included at the end of this paper to illustrate its application to a digital computer.Item Some theorems on feedback(1960) Goldwyn, Roger Martin; Graham, Martin; Pfeiffer, Paul E.; MacLane, G. R.Item Synthesis of Boolean functions with majority logic(1961) Cyprus, Joel Howard; Graham, MartinItem The design of the control section of the Rice Institute computer(1960) Deck, Philip Eugene; Graham, Martin