Analysis approaches that can be used in the design of computer-based systems for medical applications are described. The major contributions are the definition of safety and the development of analysis techniques whic...
详细信息
ISBN:
(纸本)0818608633
Analysis approaches that can be used in the design of computer-based systems for medical applications are described. The major contributions are the definition of safety and the development of analysis techniques which allow safety to be quantified. The results presented are of particular importance in medical applications where the inappropriate operation of the computer system can be catastrophic. A microprocessor-based controller developed for an electric wheelchair is described and used as an example to illustrate the basic concepts and modeling techniques. The results demonstrate that reliability considerations alone are insufficient to evaluate the effectiveness of a given design;safety must also be considered to ensure that the best design is selected for a given application.
Advances in digital electronics and transducer design have facilitated basic research concerning the response properties of neurophysiological control systems underlying speech production. Studies of orofacial sensori...
详细信息
Advances in digital electronics and transducer design have facilitated basic research concerning the response properties of neurophysiological control systems underlying speech production. Studies of orofacial sensorimotor integration during voluntary motor behaviors have shed new insight on the complex relations between brain and behavior. The objectives of the report are to describe the design and application of several specialized devices for transducing resultant forces in the lips, review the components of a precision servo mechanical stimulus generator, discuss the elements of the laboratory computer for data acquisition and stimulus control, and illustrate the utility of this technologic development in experimental studies of human perioral fine force control and reflex modulation.
Existing design methodologies do not provide adequate insight into the cause of instability in higher-order delta-sigma modulators (DSMs) used for digital-to-analog and analog-to-digital conversion. The authors presen...
详细信息
Existing design methodologies do not provide adequate insight into the cause of instability in higher-order delta-sigma modulators (DSMs) used for digital-to-analog and analog-to-digital conversion. The authors present a quasistatic approach to modeling the quantizer as a method for determining DSM loop stability. Signals in the DSM loop are separated into low-frequency (signal-related) and high-frequency (loop-noise-related) components. The quantizer is modeled as a memoryless sigmoidal nonlinearity whose shape depends on the high-frequency noise components. Stability of the DSM is determined by linearizing the quantizer at a particular DC input level. The shape of the quantizer nonlinearity, the probability density function (pdf) of the high-frequency noise components, and the range of stability for DSM loops were determined both by simulation and by experimental measurements. The range of stability determined by the quantizer model was shown to accurately predict the actual stability range.< >
Developments in the Computer Aided Life Cycle engineering (CALC) research program at the University of Maryland, USA are reported. The CALCE system program is a computer application of the Unified Life Cycle Engineeri...
详细信息
Developments in the Computer Aided Life Cycle engineering (CALC) research program at the University of Maryland, USA are reported. The CALCE system program is a computer application of the Unified Life Cycle engineering (ULCE) design process. ULCE differs from the traditional design process in that consideration is given to design issues such as performance, cost, schedule, supportability and producibility in the initial design phase as well as through the operational life of the product. A general ULCE design process is presented with emphasis on generic modeling and evaluation techniques.< >
Two time-to-digital converters are designed, with special emphasis on searching for and modeling the causes of timing jitter in CMOS devices. The time base is formed by an external high-frequency three-phase clock in ...
详细信息
Two time-to-digital converters are designed, with special emphasis on searching for and modeling the causes of timing jitter in CMOS devices. The time base is formed by an external high-frequency three-phase clock in the first design and by tapped on-chip delay-lines in the second circuit. The single-shot resolutions of the circuits are about 7 and 0.5 ns.< >
Describes a model used for the design of doped channel pseudomorphic AlGaAs/InGaAs/GaAs quantum-well HIGFETs and for the simulation of digital integrated circuits based on these devices. The model is based on the self...
详细信息
Describes a model used for the design of doped channel pseudomorphic AlGaAs/InGaAs/GaAs quantum-well HIGFETs and for the simulation of digital integrated circuits based on these devices. The model is based on the self-consistent quantum mechanical calculation of subbands and electron density in InGaAs quantum wells, obtained by solving a one-dimensional effective mass Schrodinger equation. Such a calculation shows that the potential barrier between the quasi-Fermi level in the channel and the bottom of the conduction band in the barrier layer is considerably larger for the doped-channel structure. This lowers the thermionic emission gate current of the doped channel device compared to the undoped channel structure, as confirmed by experimental data. The authors measured peak transconductance g/sub m/=471 mS/mm and peak l/sub dsat/=660 mA/mm in 0.6- mu m-gate doped-channel services. These results demonstrate the advantages of the DCHFET over the standard MODFET structure and their potential for high speed IC applications.< >
The electronic implementation of neuromorphic systems requires technologies well matched to the functions of storage and the computation of sums of products. Additional requirements are low-power, high fan-out capabil...
详细信息
The electronic implementation of neuromorphic systems requires technologies well matched to the functions of storage and the computation of sums of products. Additional requirements are low-power, high fan-out capability and high-density interconnect. Massive parallelism and redundancy mitigate the accuracy limitations of analog circuits and force consideration of analog and analog-digital components for network realization. Adaptive neuromorphic networks have the potential for self-organization and learning in speech and image understanding systems requiring minimal human intervention.< >
Neural networks have been studied for many years with the hope of achieving human-like performance in such fields as speech and image recognition. A recent resurgence has resulted from VLSI advances, neural network mo...
详细信息
Neural networks have been studied for many years with the hope of achieving human-like performance in such fields as speech and image recognition. A recent resurgence has resulted from VLSI advances, neural network models, and learning algorithms. Neural networks are also very suitable in certain areas such as NP-complete constraint and satisfaction problems, due to the nature of parallel and distributed processing. Neural network models are composed of a mass of fairly simple computational elements and rich interconnections between the elements. Neural networks operate in a parallel and distributed fashion which may resemble biological neural networks. Behaviors of neurons and the strengths of synaptic interconnections are simulated by operational amplifiers and resistors respectively. Several examples are presented, including how to build neural network components based on analog circuits for simulating neural networks and conventional logic circuits.< >
The US Space Shuttle's Ku-band system was specifically designed for communications and tracking functions which are required during on-orbit operations with other spacecraft. Operating modes permit search and acqu...
详细信息
The US Space Shuttle's Ku-band system was specifically designed for communications and tracking functions which are required during on-orbit operations with other spacecraft. Operating modes permit search and acquisition to be accomplished by computer designation or under manual control by the astronaut. Ku-band system data channels drive on-board dedicated displays and are incorporated into state vector updates by Shuttle guidance and navigation computers. Radar-cross-section estimates were used in computer simulations to predict the range at which radar detection and acquisition can be expected. Validity of the simulation model and the radar design and performance were verified by flight tests on the White Sands test range. It is concluded that results of the testing established confidence in the capability of the system to provide the relative position and rate information which is needed for Shuttle work involving other spacecraft.< >
The Deep Submergence Laboratory at the Woods Hole Oceanographic Institution is currently developing supervisory control system methodologies for underwater vehicles and manipulators. An effective low-level control sys...
详细信息
暂无评论