Showing papers by "University of Colorado Colorado Springs published in 1981"

Solvability, controllability, and observability of continuous descriptor systems

Abstract: In this paper, we investigate the properties of the continuous descriptor system E\dot{x}(t)=Ax(t)+Bu(t), 0\leqt\leqb where E, A, and B are complex and possibly singular matrices and u(t) is a complex function differentiable sufficiently many times. The traditional approach to such systems is to separate the state equations from the algebraic equations. However, such algorithms usually destroy the natural, physically-based sparsity and structure of the original system. Therefore, we consider descriptor systems in their original form. Such systems possess numerous properties not shared by the well-known state variable systems. First, we relate classical theories of matrix pencils to the solvability of descriptor systems. Then we extend the concepts of reachability, controllability, and observability of state variable systems to descriptor systems, and describe the set of reachable states for descriptor systems.

Analysis of descriptor systems using numerical algorithms

Abstract: In this paper we analyze numerical methods for the solution of the large scale dynamical system E\dot{y}(t)=Ay(t)+g(t),Y(t_{0})=y_{0} , where E and A are matrices, possibly singular. Systems of this type have been referred to as implicit systems and more recently as descriptor systems since they arise from formulating system equations in physical variables. Special cases of such systems are algebraic-differential systems. We discuss the numerical advantages of this formulation and identify a class of numerical integration algorithms which have accuracy and stability properties appropriate to descriptor systems and which preserve structure, detect nonsolvable systems, resolve initial value consistency problems, and are applicable to "stiff" descriptor systems. We also present an algorithm for the control of the local truncation error on only the state variables.

Redundancy scheme for a dynamic ram

Abstract: A redundancy scheme for a dynamic memory is arranged to replace defective main memory cells with spare memory cells. The memory array is divided into first and second sectors (L, R), the first sector (L) containing a portion (184) of each main memory column and one or more spare columns (186), and the second sector (R) containing the remaining portion (188) of each main memory column and one or more spare columns (190). Means (192, 194, 196, 198) are provided for accessing the main memory columns and the spare memory columns such that, when a portion (184) of an addressed main column in said first sector (L) is defective and its remaining portion (188) in said second sector (R) is not defective, the non-defective portion (188) of said addressed column is accessed and a spare replacement column (186, 190) in one of said sectors (L, R) is accessed in place of the defective portion of the addressed column. Means (218, 220, 222) are provided for coupling the data associated with the accessed portion of the addressed column and the replacement spare column to a data output (200).

Microsurgical laser device

Abstract: Microsurgical laser device for guiding a laser beam to a desired target The device includes a laser head supported in a relatively horizontal orientation by a counterbalanced articulated support arm which provides for elevational positioning of the laser head as well as rotation of the laser head about two parallel spaced apart vertical axes The support arm, in turn, is rotatably supported by a vertical post defining a third vertical axis Threadably connected to one end of the laser head is an articulated laser guide arm having a precision telescopic first section followed by four rotatable mirror sections each of which is adapted to redirect a beam 90° along a plane perpendicular to the axis of the incident path Each section is precision made to obviate the need to adjust the mirror or align the arm The support arm permits easy approximate positioning of the laser head in the vicinity of the laser beam target while the relatively short pre-aligned articulated laser beam guide provides for quick precise aiming of the laser beam The vertical post is supported by a base cabinet that contains the power supplies The controls of the laser beam characteristics such a power level and time of exposure are contained on a moveable control console that is separate from the base cabinet

Asynchronously equilibrated and pre-charged static ram

Abstract: In a static RAM fully asynchronous active equilibration and pre-charging of the RAM's bit lines (24) provides improved memory access time and lower active power dissipation. Each change in the memory's row (34) address is sensed for developing a clock pulse (50) of a controlled duration. The clock pulse (50) is received by a group of equilibrating transistors (46) and a group of pre-charging transistors (46) which are coupled to the memory's bit lines. When the clock pulse (50) occurs, all the above-mentioned transistors (46) conduct to effect simultaneous equilibration and pre-charging of the bit lines (24).

Passivity considerations in stability studies of numerical integration algorithms

Abstract: In this paper we introduce the concept of algorithmic passiv- in in ity and indicate its role in circuit and timing simulation programs Algorithmic passivity shows the overall stability--or lack thereof--inherent in forward Euler, backward Euler, and trapezoidal one-step integration approximations as well as Gear's two-step method Passivity can be applied to - Vi_ _ Vn-i+ i integration algorithms to provide sufficient conditions for the overall stability of simulation programs that may employ them on an intermixed basis

General Software for Two-Dimensional Nonlinear Partial Differential Equations

Abstract: In this paper we describe a software interface to solve time-dependent coupled systems of nonlinear partial differential equations (PDEs), which are defined over a two-dimensional rectangular rebqon. The software interface employs the method of lines technique whereby centered differencing with respect to the two spatial variables results in a system of time-dependent ordinary differential equations (ODEs), which can then be solved using one of the readily available modern ODE integrators. We also describe a routine to be used in conjunction with the interface for the efficient generation of the Jacobian matrix. Representative examples are given to demonstrate the use, validity, and capabihties of the accompanying algorithm.

A 100ns 64K dynamic RAM using redundancy techniques

Abstract: A 64K×1 dynamic RAM with 100ns access time, fault-tolerant circuitry, high-speed serial data output and on-chip refresh circuitry, without the use of pin 1 for control, will be reported.

High speed data transfer for a semiconductor memory

Abstract: A system is described for use in a semiconductor memory for rapidly transferring data between a plurality of successive memory locations and a data output buss The system includes a plurality of data latches for storing data derived from successive locations in memory, and a corresponding plurality of serially coupled decoders, each associated with one of the data latches In response to an address input, one decoder is enabled for causing its associated data latch to output its stored data to the data buss The latter decoder then disables itself and enables the next decoder so that a second latch outputs its stored data The process continues with each decoder disabling itself and enabling the next decoder so that the data latches are caused to sequentially output their stored data

A comparison of the actions of H1 and H2 antihistamines on histamine-induced bronchoconstriction and cutaneous wheal response in asthmatic patients.

Abstract: The effect of an H 1 antihistamine, an H 2 antihistamine, and the combination of the two drugs on both histamine-induced bronchoconstriction and dermal whealing was examined in five patients with mild asthma. Chlorpheniramine 8 mg, cimetidine 300 mg, the combination of both, and placebo were administered orally to each patient for a single dose and for seven consecutive doses given every 6 hr after a double-blind, randomized protocol. The airway response to inhaled histamine and the wheal size induced by the intradermal injection of histamine were determined in every patient 2 hr after the final drug dose. The results indicate that a single dose of chlorpheniramine produces a significant increase in the threshold of histamine-induced bronchoconstriction as measured by the provocative histamine dose producing 20% decrease in 1-sec forced expiratory volume (PD 20 -FEV 1 ), and this effect was significantly enhanced after seven doses. Cimetidine caused a significant decrease in the threshold of histamine-induced bronchoconstriction, but this was not augmented by seven doses. Only chlorpheniramine, when given for seven doses, improved the baseline FEV 1 and forced expiratory flow during middle half of forced vital capacity (FEF 25%–75% ). Chlorpheniramine in both single and multiple doses and the combination of chlorpheniramine and cimetidine given for seven doses produced a significant inhibition of histamine-induced dermal wheals, whereas cimetidine alone had no effect. These results confirm our previous observation that both H 1 and H 2 receptors are present in the airways of asthmatic patients and that they mediate opposite effects. We also demonstrated a cumulative effect with the repeated administration of chlorpheniramine but not with cimetidine. Finally, the results suggest that the role of H 1 and H 2 receptors differs in the bronchi from that seen in the dermal vessels of asthmatic patients and are in contrast to these of normals. The H 2 receptor effect on histamine-induced skin wheals appears deficient, further supporting earlier suggestions of the presence of an H 2 receptor defect in asthmatic patients.

Bootstrap driver circuits for an MOS memory

Abstract: A high speed, low power bootstrap driver is disclosed for use in an MOS memory. The basic driver includes first and second enhancement mode transistors (12, 14) for receiving a digital input (16). The drain of the first transistor (12) is coupled to a high impedance depletion mode transistor (22), and the drain of the latter transistor is coupled to the source of a low impedance transistor (26). Another enhancement mode transistor (30) is coupled via its sources to the drain of the second enhancement mode transistor (14) and is coupled via its gate to the drain of the first enhancement mode transistor (12). A capacitor (34) is connected between the drain of the high impedance transistor (22) and the drain of the second enhancement mode transistor (14). When a low level input is received, the drain of the first enhancement mode transistor (12) is rapidly bootstrapped to a high level voltage above the positive power supply for use as an output signal (18).

Method of fabricating self-aligned MOS devices and independently formed gate dielectrics and insulating layers

Abstract: A method is described for fabricating MOS devices of the type found in very large scale integrated circuits. According to the method described herein, various gate oxides and insulating layers are fabricated independently of each other in order to independently tailor their thicknesses and thereby provide improved isolation between gate electrodes and interconnects, and independently controllable operating characteristics for multiple gate electrode structures. The fabrication of a dynamic RAM memory cell, an overlapping gate CCD device and a self-aligned MNOS transistor cell are described using the disclosed method.

A curvature corrected micropower voltage reference

Abstract: This paper will describe a modified bandgap voltage reference circuit for compensating the inherent thermal nonlinearity of the emitter-base potential.

Apparatus for determining the concentration of a fluorescent material in an eye

Abstract: A fluorophotometer for determining the concentration of a fluorescent material in an eye, including a light source producing a beam of light traversing a path in the eye to excite the material to emit fluorescence, optics for imaging the path and fluorescence at a detecting plane, a linear photodiode array at the detecting plane for detecting the fluorescence along the path, and a microprocessor for collecting data from the array and producing information of the concentration of the fluorescent material.

Folded bit line-shared sense amplifiers

Abstract: A folded bit line-shared sense amplifier arrangement is described for sensing the logic state of an accessed memory cell in a dynamic MOS random access memory. In the preferred embodiment, a shared sense amplifier is positioned between and coupled to first and second bit lines via first and second isolation transistors. The same shared sense amplifier is also positioned between and coupled to third and fourth bit lines via third and fourth isolation transistors. When the state of an accessed memory cell is to be sensed, its memory cell capacitor is coupled to a selected bit line and a dummy cell capacitor is coupled to the bit line adjacent the selected bit line. A decoding circuit selectively activates the shared sense amplifier to sense a difference in voltage between the selected bit line and its adjacent bit line so as to determine the logic state associated with the accessed memory cell. Then, the sense amplifier latches into this logic state for reading by the input/output buss lines. After the logic state is read, the selecting circuit enables the memory cell capacitor to be refreshed for further sensing by the sense amplifier.

Theory of the Motion of an Artificial Earth Satellite

Abstract: An improved analytical solution is obtained for the motion of an artificial Earth satellite under the combined influences of gravity and atmospheric drag. The gravitational model includes zonal harmonics throughJ 4, and the atmospheric model assumes a nonrotating spherical power density function. The differential equations are developed through second order under the assumption that the second zonal harmonic and the drag coefficient are both first-order terms, while the remaining zonal harmonics are of second order. Canonical transformations and the method of averaging are used to obtain transformations of variables which significantly simplify the transformed differential equations. A solution for these transformed equations is found; and this solution, in conjunction with the transformations cited above, gives equations for computing the six osculating orbital elements which describe the orbital motion of the satellite. The solution is valid for all eccentricities greater than 0 and less than 0.1 and all inclinations not near 0o or the critical inclination. Approximately ninety percent of the satellites currently in orbit satisfy all these restrictions.

Loading dock canopy

Abstract: A loading dock canopy comprising a frame having a top, opposite sides, an inner face, an outer face, and a center access opening adapted to be aligned with the loading access opening of the loading dock. The frame is of resilient construction to permit deflection thereof, and an elastic material covers at least the top of the frame, with suitable covering material extending over the sides thereof. Inner and outer vertical members comprise the sides of said frame. Spring means extend therebetween to hold said vertical members apart. Cables limit the relative movement of said vertical members. Hinge means at the top of the frame facilitate the deflective capabilities of said frame.

Reformulation of the Brouwer Geopotential Theory for Improved Computational Efficiency

Abstract: The theory, as derived by Brouwer and later modified by Lyddane, of the motion of an artificial Earth satellite perturbed by the first five zonal harmonics is reformulated in terms of an alternate set of variables. This alternate set of variables produces an equivalent solution, has no small eccentricity or small inclination restrictions, and allows calculation of position and velocity with considerably fewer algebraic and trigonometric operations. In addition, the alternate set of variables avoids one solution of Kepler's equation.

Economizer refrigeration cycle space heating and cooling system and process

Abstract: This invention relates to heating and cooling systems and more particularly to an improved system utilizing a Stirling Cycle engine heat pump in a refrigeration cycle.

Algorithm 565: PDETWO/PSETM/GEARB: Solution of Systems of Two-Dimensional Nonlinear Partial Differential Equations [D3]

Abstract: The algorithm presented here combines P D E T W O , PSETM[1] , and a modified version of GEARB[2] to form a complete partial differential equations package for systems of t ime-dependent nonlinear partial differential equations defined over a two-dimensional rectangular region. The descriptions of P D E T W O and P S E T M , test results, references, and the use of this algorithm are contained in the authors ' paper [2]. The ordinary differential equations package, GEARB, is described by Hindmarsh [1], so we only comment on those modifications tha t we made to G E A R B for this algorithm. The principal modification is the addition of a new subroutine to set pointers for dynamic dimensioning of arrays and to check the validity of some of the user input parameters. The interpolation routine in G E A R B was also modified so tha t it would re turn correctly interpolated solution values at the-user-specified output time for t ime-dependent boundary conditions. Machine-readable documenta t ion within the package serves as a complete user 's guide. The comments in subroutine P D E T W O give the essential details on

Leiomyosarcoma of the rectum: the military experience.

Abstract: Leiomyosarcoma of the rectum is a rare neoplasm and may behave in a highly malignant manner. Our experience with a single case prompted a review of the Armed Forces Central Medical Registry (AFCMR), where six other cases were found from the total AFCMR population. Four patients were treated with abdominoperineal (AP) resection; three had local excision only. Three patients developed metastatic disease and two of those died. The authors recommed prompt wide excision (AP resection) for any case of leiomyosarcoma of the rectum.

Two-way regulated substrate bias generator

Abstract: An improved substrate bias generator for MOS integrated circuits is described. The generator includes circuitry for generating two trains of periodic pulses which are approximately phase opposite, one of the pulse trains being slightly delayed as compared to the other pulse train. The two pulse trains are applied to a pumping circuit which generates a target voltage and initially transfers a positive charge into the substrate, and thereafter transfers a positive charge out of the substrate. The positive charge transferred out of the substrate is greater than the positive charge transferred into the substrate when the absolute value of the potential on the substrate is less than the target voltage. Otherwise, a net positive charge is transferred into the substrate. In this manner, the absolute value of the potential on the substrate is driven towards the target voltage.

MOS Capacitive bootstrapping trigger circuit for a clock generator

Abstract: A trigger circuit is described for use in an MOS clock generator. The clock generator is the type which uses a conventional double bootstrapping circuit coupled to a control transistor to develop a high level clock output signal. The trigger circuit preconditions the control transistor to facilitate proper bootstrapping operation. Included in the trigger circuit is a plurality of interconnected transistors which respond to a pre-charge signal and then a warmup signal for turning the control transistor off and then for establishing selected potentials at the electrodes of the control transistor to precondition it for bootstrapping. In response to a subsequent trigger signal, the trigger circuit enables the control transistor for developing a high level clock output signal.

Closed-Form Solution for Ballistic Vehicle Motion

Abstract: A closed-form solution is developed for the motion of a ballistic vehicle entering the atmosphere over a flat nonrotating Earth. The Alien and Eggers approach of using an exponential atmosphere is retained; however, the vehicle drag coefficient is expressed as a function of velocity instead of being considered a constant. Use of the derived equations allows an analyst to solve directly for the vehicle velocity at any point along the trajectory, as well as for the maximum axial acceleration and the altitude at which it occurs.

Single polycrystalline silicon static FET flip flop memory cell

Abstract: A single polycrystalline silicon configuration for a memory cell (10,12) in a static MOS RAM utilizes three conductivity regions. A first conductivity region (42) is formed in the substrate (38) to create a buried ground line (26) and sources and drains of transistors (16,18,28,30). A second conductivity region (60) is formed within an insulation layer (40) and above the first conductivity region (42) to create a word line (36), gate regions of the transistors, load resistors (20,22), and a power supply line (24). The power supply line (24) is oriented directly above and parallel to the ground line (26). A third conductivity region (84) is formed on the surface of the insulation layer (40) to create data lines (32,34). The number of process steps and the size of the memory cell are reduced by this configuration.