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Date 1-4 April 1990

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Displaying Results 1 - 25 of 240
  • SOUTHEASTCON '90. Proceedings (Cat. No.90CH2883-7)

    Publication Year: 1990
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    Freely Available from IEEE
  • 'Hands-off' - Voice activated automated anesthesia recordkeeping and monitoring system (ARMS)

    Publication Year: 1990 , Page(s): 822 - 824 vol.3
    Cited by:  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (179 KB)  

    The development of an inexpensive pilot anesthesia recordkeeping and monitoring system (ARMS) for use during surgery is described. This IBM-PC-based system permits automated acquisition and storage of physiologic data obtained continuously from anesthetized patients during surgery. Additionally, graphic displays have been developed to trend changes in relevant physiologic variables. Operation of this automated recordkeeping system is under voice control of the anesthesiologist. Voice control also permits accurately timed annotation of the automated anesthesia record even when the user is otherwise occupied. Speech synthesis offers operating instructions to the user, verifies the accuracy of voice entries and provides discrete, unambiguous warning messages.<> View full abstract»

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  • Erasure communication channel statistics

    Publication Year: 1990 , Page(s): 1056 - 1061
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    Three categories of density functions are demonstrated for an erasure communication channel where the output is restricted to being greater than some threshold. The exponential, gamma, and geometric variables are in the first category by a variance that goes to a constant value as the threshold goes to infinity. The Gaussian, Rayleigh, and Poisson random variables are in a second category characterized by a variance that goes to zero as the threshold goes to infinity. In the last category is the power law random variable characterized by a variance that goes to the infinity as the threshold goes to infinity. The first category is described by an exponential drop-off of the density function or the probability function, the second category by a drop-off that is more rapid than exponential, and the last category by a drop-off that is less rapid than the exponential.<> View full abstract»

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  • Comparison of sample averaging and integrate and dump for measurement of mean radiation in tracer experiment

    Publication Year: 1990 , Page(s): 1085 - 1088 vol.3
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    A software model of a gas filter radiometer has been constructed for simulation to determine the effect of varying certain system parameters. The radiometer measures the mean of chopped radiation by averaging over 64 chopper cycles. System bandwidth and quantization of the sampling process are investigated for optimal performance. Results indicate that lower bandwidths and a quantisation length of 12 bits provide the best measurement for this investigation. An evaluation of parameter tradeoffs is presented based on analytical results. The measurement process is also described View full abstract»

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  • The application of duals in the analysis of Petri nets

    Publication Year: 1990 , Page(s): 72 - 76 vol.1
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    The closeness algorithm, an algorithm which guides the selection of the best form of either a primal or a dual for further analysis, is presented. The primal refers to the original Petri net, and a dual is a transformation of the primal form of a net. The use of the closeness algorithm is limited to a subclass of Petri nets called free-choice nets, where the primal and dual are both live and safe. The closeness algorithm can be very useful in simplifying the analysis of a Petri net. In the examples given, the time involved in generating all the states of a net is reduced by choosing the form of the net that will produce the fewest states View full abstract»

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  • Newton-Cotes rules for triple integrals

    Publication Year: 1990 , Page(s): 471 - 475 vol.2
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    A simple algorithm based on Newton-Cotes rule for evaluating a multidimensional integral is provided. The Newton-Cotes rules are discussed. The evaluation of a three-dimensional integral is discussed. The algorithm can be extended to evaluate integrals with more than three dimensions View full abstract»

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  • Ground-based surveillance and tracking system (GSTS) software development methodology

    Publication Year: 1990 , Page(s): 77 - 78 vol.1
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    Software development for the ground-based surveillance and tracking system (GSTS) is described. The overall objectives of the GSTS demonstration/validation (DEM/VAL) program is to reduce technical and cost risks associated with a decision to enter the full-scale development (FSD) phase. Some of the techniques to reduce risk in this program include modern software engineering practices, automated environments, software reuse, fast evolutionary prototyping, rational tailoring of military standards, and software personnel involved early in the system-requirements specifications. The application of these techniques for risk mitigation is described. Optimal application of the various techniques is not always feasible because of a number of legal/contractual, experiential, schedule, programmatic, and resource constraints. Satisfactory decisions or factors considered in selecting alternative approaches are elaborated View full abstract»

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  • In-simulator assessment of trade-offs arising from mixture of color cuing and monocular, binoptic, and stereopsis cuing information

    Publication Year: 1990 , Page(s): 583 - 588 vol.2
    Cited by:  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (520 KB)  

    Research done to assess the tradeoffs arising from the mixture of color cueing and monocular, binocular, and stereopsis cueing information in peripheral monitoring displays encountered in helmet-mounted display (HMD) systems is discussed. The accompanying effect of stereopsis cueing in the foveal display of tracking information was assessed. A description of the simulator as well as experimental results are provided. The results of this experiment indicate that binoptic display of monitoring information in the right-peripheral region, with color cueing as an alerting function, to such information, and stereopsis cueing in the central region of the display, were the most effective display conditions examined. To obtain the advantages, of binocular summation with binoptic displays in the peripheral region, a sacrifice in total field of view (FOV) is required. The performance gains realized from binoptic or stereopsis cueing over monocular display in the periphery require a loss of total FOV that may not be justified for all applications View full abstract»

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  • FIS: an AI-based fault isolation system

    Publication Year: 1990 , Page(s): 770 - 774 vol.2
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    An artificial intelligence (AI)-based fault-isolation system (FIS) is discussed. It was developed primarily for use with large-scale analog hybrid electronic systems such as radar and sonar systems, but it is applicable at least in principle to any human-engineered system with discrete replaceable components. An overview of the system and a description of some of its current application areas are given. A brief overview of the architecture of the FIS system is also given View full abstract»

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  • Computer viruses: detection and prevention techniques

    Publication Year: 1990 , Page(s): 199 - 201 vol.1
    Cited by:  Patents (1)
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    Presents useful methods of infection detection and prevention to be adopted by organizations or individuals in response to the potential threat posed by computer viruses. To cope with the problem, diverse antiviral programs were introduced and are currently being used by many as a reliable form of first-line defense against viruses. These programs provide a good way of generally detecting and/or preventing computer viruses. The types of viruses and the types of detection/prevention programs to cope with them are outlined. Complete protection from viral infection is not feasible. None of the proposed protection schemes can completely stop computer viruses. The challenge in detecting and preventing viruses is to distinguish legitimate activities from those caused by viruses. Technical competence about the system and the use of antiviral programs can help contain the threat of viral infection View full abstract»

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  • Investigation of methodologies for generating monthly energy sales forecasts

    Publication Year: 1990 , Page(s): 137 - 139 vol.1
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    An accurate monthly energy sales forecast leads to a more precise allocation of required resources to generate electricity, thus optimally directing cash flow for the individual electric utility company's budgeting process. The techniques used to develop the monthly forecasts are discussed. Initially, twelve different methodologies were identified and used to develop monthly energy sales by sector over the historical period of 1986 to 1988 for one of the four operating companies in the Middle South Electric System. These results were then compared to the actual sector monthly energy sales for those respective years. The four best methodologies were chosen for individual sectors and results validated by using these methods in a similar fashion in the other three operating systems View full abstract»

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  • Determining the discrete equivalent Kalman steady state gain for the LQR problem

    Publication Year: 1990 , Page(s): 911 - 913 vol.3
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    A method of mapping the continuous steady-state Kalman gain to a discrete equivalent is developed and presented. Using continuous and discrete system relationships makes it possible to derive a method for relating the continuous Kalman gain to a discrete equivalent. The method determines the weighting matrices necessary to locate the closed-loop eigenvalues in a specified region of the s-plane so only a continuous gain can be computed, but by making use of the relationship of the closed-loop continuous model and its discrete equivalent a relationship for the discrete Kalman gain can be determined based on computed quantities. The relationship is an overdetermined system of linear equations in the elements of the unknown Kalman discrete gain matrix. Using the least-squares method makes it possible to solve the system for the discrete Kalman steady-state gain. The eigenvalues of the continuous time closed-loop system can be mapped directly to the z -plane based on the sample rate and then compared with the z -plane closed-loop eigenvalues found on the basis of the determined discrete steady-state gain View full abstract»

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  • A dynamic vision classification system using Fourier descriptions

    Publication Year: 1990 , Page(s): 424 - 426 vol.2
    Cited by:  Papers (1)
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    The design and implementation of a vision classifier system which can display, label, and identify different known objects in applicable images is presented. Every object can be described during the training phase or classified during the recognition phase according to the normalized Fourier descriptors obtained from sampling its boundary. These descriptors are invariant to the rotation, size, and orientation of the corresponding object. The system allows the user to dynamically train and store new patterns in the appropriate knowledge base of patterns. It is implemented on an AI VAXstation. The descriptors provide an increasingly accurate characterization of shape as more coefficients are included. Each descriptor is a measure of the lobedness of the subject. The descriptors provide accurate classifications for all objects tested under moderate noise and small distortion View full abstract»

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  • Broadband resonance effects in power lines with sectionalized shield wires

    Publication Year: 1990 , Page(s): 654 - 658 vol.2
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (304 KB)  

    A frequency-domain analysis of three-phase overhead power lines with sectionalized shield wires is presented. An odd-type interphase power-line carrier energization is assumed, and a range of frequencies is considered such that the spacing between adjacent towers approaches one-half wavelength. Simulation results show that the transmission line behaves as a bandstop filter. Important broadband resonance effects are shown taking place, with carrier transmission performance being severely affected View full abstract»

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  • PRNS approach to fast FIR filtering

    Publication Year: 1990 , Page(s): 223 - 227 vol.1
    Cited by:  Papers (1)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (292 KB)  

    A system for the implementation of fast finite impulse response (FIR) filtering in digital signal processing (DSP) operations is outlined. The system uses only real arithmetic and possesses many of the good numerical characteristics of the discrete Fourier transform (DFT)-based implementations. The basic concept underlying the implementation is that of polynomial residue number systems (PRNS). PRNS is used as an efficient way for computing polynomial products. This concept allows the computation of cyclic convolutions in a completely concurrent form. Some aspects of the hardware implementation in the scheme of butterfly modules and in systolic architectures are analyzed View full abstract»

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  • Test and evaluation of the SVID-compliant REAL/IX realtime operating system

    Publication Year: 1990 , Page(s): 81 - 85 vol.1
    Cited by:  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (436 KB)  

    The unique challenges encountered and techniques used in verifying the proper operation and performance of the REAL/IX operating system, a fully preemptive, low-latency operating system based on AT&T's Unix system V release 3, are described. The current release of the system runs on a hardware configuration based on the Motorola MC68030 microprocessor. Extensions to the operating system provide facilities required by real-time applications, some of which yield the low interrupt latency and I/O system throughput required by real-time applications, such as: fixed-priority process scheduling; real-time permission control; resident program support through memory preallocation; high-performance common event notification; real-time timer mechanism; asynchronous, direct, and nonbuffered file I/O; connected interrupt mechanism; user-extensible kernel for device drivers and system services; and fast file systems. The testing effort confirmed the functionality of these features and their ability to provide real-time performance in applications. General system testing was also required to ensure that these new facilities had not inadvertently altered other standard functions View full abstract»

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  • Simulating topographic features with fractals

    Publication Year: 1990 , Page(s): 427 - 429 vol.2
    Cited by:  Patents (1)
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    The simulation of naturally occurring topographical features using fractals is described. Features are indicated on an image array by position, shape, and intensity. The shape is indicated by a skeleton outlining the contours of the feature. The fractal image is created using a recursive subdivision method, also known as midpoint replacement, in conjunction with the skeleton of the feature. Images with a variety of features are presented View full abstract»

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  • Hopfield neural network for AR spectral estimator

    Publication Year: 1990 , Page(s): 562 - 566 vol.2
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    An autoregressive (AR) spectrum estimator which uses the Hopfield neural network (HNN) is introduced. The HNN is designed to minimize the mean squared error between a subject signal and the assumed AR model of that signal. The output of the HNN consists of the AR coefficients, so that the spectrum of the signal can be directly obtained in terms of the AR coefficients and the sampling interval. A symmetric soft-limiter-type neuron was selected for the HNN. Simulation results are provided View full abstract»

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  • Echo cancellation using a two-stage block LMS algorithm [ISDN]

    Publication Year: 1990 , Page(s): 972 - 974 vol.3
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    A two-stage block least-mean-square (LMS) algorithm which can be used in data echo cancellation to realize full-duplex digital data full-duplex transmission is proposed. The block LMS algorithm is implemented in two stages where there is an individual convergence factor at each stage. The convergence factor is changed according to the sign correlation between the echo signal and the error signal during the convergence process. The convergence property of the algorithm is investigated. Computer simulation results are given to verify the performance improvement. The computation saving is achieved because the coefficients are updated for each block, and it also allows rapid convergence. Therefore, the two-stage block LMS algorithm is a better choice than the conventional LMS algorithm in data echo cancellation View full abstract»

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  • A large nonblocking optical crossbar for parallel processing

    Publication Year: 1990 , Page(s): 29 - 32 vol.1
    Cited by:  Patents (1)
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    The implementation of a large switching network using optical switching technology and components is considered. Optical crossbar switching networks using spatial light modulators (SLMs) offer a solution to the bottleneck of connecting processors, memory modules, and input/output devices in a large parallel processing computer system View full abstract»

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  • A distributed sensor and processor for surface control of a large reflector

    Publication Year: 1990 , Page(s): 122 - 125 vol.1
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    The design and performance of a distributed optical sensor and processor for surface control of large reflectors are presented. The distributed optic sensor is a type of holographic contour mapper. Holographic images of the reflector surface are recorded in real time using multifrequency laser light. The stored holograms are used to generate contour maps of the surface which provide distributed measurements of the displacement of the surface. These contour maps may be processed optically to yield control signals to drive a finite number of actuators to control the shape of the surface. Real-time holographic sensing of the reflector surface is accomplished using a new optical image storage device. This storage device, which is being developed at NASA Langley Research Center, records and stores holographic images in photorefractive crystals. The information storage density of the crystals is high, thus allowing high restoration images to be stored. The theory of operation of the device and an estimate of sensor performance are discussed View full abstract»

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  • Plane wave shielding effectiveness of conductive polymer films

    Publication Year: 1990 , Page(s): 38 - 41 vol.1
    Cited by:  Papers (1)
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    A new material, the conductive polymer poly-p-phenylene-benzobis-thiazole (PBT) doped by ion-implantation with iodine, was studied for its possible utilization as a microwave shield. The conductivity of the polymer was measured at a frequency of 10 GHz by the cavity perturbation technique. Layered-media electromagnetic theory was applied to compute the overall reflection and transmission coefficients of the polymer, modeled by contiguous planar layers of doped and undoped constituents. The field transmitted through the polymer was observed to have a small amplitude over the microwave frequency range of 2 GHz to 10 GHz, indicating potential usefulness of the polymer as an electromagnetic interference (EMI) shield in an environment containing high-data-rate electronics, such as supercomputers View full abstract»

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  • Linear piezoelectric step motors

    Publication Year: 1990 , Page(s): 21 - 29 vol.1
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (212 KB)  

    The design of a linear step motor using piezoelectric material is presented. The principle of operation is based on the characteristics of piezoelectric ceramics, which have a relationship between pressure and voltage. This motor can achieve a very-high-precision positioning. The resolution can be as high as 0.1 μm to 10 Å, depending on the operating voltages and the dimension of the piezoelectric ceramic for a specific application. Due to the slow response of the mechanical clutches, the system cannot be driven very fast. It takes 104 s to generate a 2.74 cm displacement View full abstract»

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  • Model for a class of temperature control systems

    Publication Year: 1990 , Page(s): 836 - 841 vol.3
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    A temperature control system is described consisting of a small metallic oven enclosed with insulation material, a power transistor for the heating element, an operational amplifier, and a thermistor for the temperature sensor. Industry has only recently begun to use the power transistor itself as the sole source of heat instead of a conventional resistive heater network which spreads the heat over a wide area. This arrangement is attractive because it eliminates the heater winding (relatively expensive and unreliable), but it does have different thermal properties from those provided by the conventional method. The objective of the research is to approximate the thermal transfer function that exists between the power transistor and the thermistor based on experimental data. The results provide information on relatively small heat control systems in which the controller active element is the heating element itself View full abstract»

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  • Methods of reactive power compensation and suppression of load-generated harmonics

    Publication Year: 1990 , Page(s): 659 - 663 vol.2
    Cited by:  Papers (1)
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    Some results of a comparative study on methods of reactive power compensation and suppression of load-generated harmonics are presented. The effectiveness of various compensating and filtering (Co-Fi) circuits for reactive power compensation and for reducing harmonic distortion and the harmonic interference index is compared. The comparison is made under the assumption that the Co-Fi circuits are used for suppression harmonics generated by a 6 and 12-pulse, 3-phase, controlled AC/DC converter View full abstract»

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