Showing papers by "University of Colorado Colorado Springs published in 1980"

SHARF: An algorithm for adapting IIR digital filters

Abstract: The concept of adaptation in digital filtering has proven to be a powerful and versatile means of signal processing in applications where precise a priori filter design is impractical. Adaptive filters have traditionally been implemented with FIR structures, making their analysis fairly straightforward but leading to high computation cost in many cases of practical interest (e.g, sinusoid enhancement). This paper introduces a class of adaptive algorithms designed for use with IIR digital filters which offer a much reduced computational load for basically the same performance. These algorithms have their basis in the theory of hyperstability, a concept historically associated with the analysis of closed-loop nonlinear time-varying control systems. Exploiting this theory yields HARF, a hyperstable adaptive recursive filtering algorithm which has provable convergence properties. A simplified version of the algorithm, called SHARF, is then developed which retains provable convergence at low convergence rates and is well suited to real-time applications. In this paper both HARF and SHARF are described and some background into the meaning and utility of hyperstability is given, in addition, computer simulations are presented for two practical applications of IIR adaptive filters: noise and multi-path cancellation.

Airborne and ground‐based studies of thunderstorms in the vicinity of Langmuir Laboratory

Abstract: Flights through the central regions of thunderstorms were made over New Mexico on 6 and 15 August 1977 with the ONR/NMIMT Schweitzer aeroplane which carried equipment designed to measure all three components of the electric field, and the charge, Q, and diameter, d, of individual precipitation elements. On the earlier day, information was also obtained with: a rain-gauge network surrounding Langmuir Laboratory; a 3 cm radar; an acoustic system for locating lightning channels; a ground-based field-change meter. The first cell on 6 August produced precipitation at the ground but no lightning. Vertical fields, Ex, of up to about 50kVm−1 and precipitation charge densities ρ of up to −0.5 C km−3 were recorded within the cloud. The second cell, which grew as the first one decayed, produced 7 lightning strokes in 9 minutes during which time the radar revealed vigorous vertical growth in a narrow zone containing precipitation. Thunder reconstructions showed the acoustic sources for the first flash of this cell to be very near the top of the cloud at an altitude of 10 km a.s.1. The subsequent flashes produced acoustic signals from progressively lower in the cloud. When the radar echo reached its maximum height lightning activity ceased. Ex values of up to about 50kVm−1 and pp values of down to −1 Ckm−3 were measured. ρp was consistently negative, individual charges being less than ±40 pC. Q values were within the inductive limit for a thundercloud at breakdown but no systematic relation between Q and d was found. Six penetrations were made through the thundercloud of 15 August, which produced only two lightning strokes. The Ex records were indicative of a (±) dipole located near the cloud top, at around –13°C. Fields of up to about 100kVm−1 and ρp values (positive and negative) of around 5Ckm−3 were measured. Q values of up to ±250 pC were recorded, with charges around ±50 pC being commonly found. No systematic Q-d relation was revealed, and smaller precipitation particles frequently carried charges (positive or negative) in excess of the inductive limit. On both days estimated precipitation rates were of order 10mmh−1 and on most occasions the pilot reported precipitation particles to be either ‘ice’ or ‘mixed liquid water and ice’.

Monolithic semiconductor integrated circuit ferroelectric memory device, and methods of fabricating and utilizing same

Abstract: A monolithic semiconductor integrated circuit-ferroelectric device is disclosed together with the method of manufacturing same. The ferrelectric device preferably consists of a layer of stable ferroelectric potassium nitrate disposed between electrical contacts positioned on opposite surfaces of the ferroelectric layer. The ferroelectric layer has a thickness of less than 110 microns, and preferably falling within a range of from 100 Angstrom units to 5,000 Angstrom units. The process of manufacturing the monolithic structure is multi-stepped and is particularly adapted for fabricating a potassium nitrate ferroelectric memory on a semiconductor integrated circuit.

What limits primates

Abstract: Recently ecological data on spider and howler monkeys at Tikal, Guatemala, have been used in an attempt to demonstrate that primate populations are not limited by food resources. Those data are shown here to be inadequate for testing hypotheses about population limitation, and the problem of discerning limiting factors is explored.

Substrate bias generator

Abstract: A substrate bias generator for an integrated circuit, metal-oxide-semiconductor (MOS) random access memory (RAM) is described. The on-chip generator includes two input terminals for receiving first and second trains of periodic pulses. The periodic pulses have the same frequency and are phase synchronized. However, the first train of pulses has a greater duty cycle than the second train of pulses. Amplitude transitions associated with the first and second trains of pulses are capacitively coupled to first and second nodes, respectively. A pair of transistors are coupled to the nodes, one transistor for clamping the first node to ground when the second node receives a positive-going voltage transition, and another transistor for selectively coupling amplitude transitions from the first node to the second node. In operation, both nodes are driven more negative with each successive incoming pulse until they reach about -5 volts for the case in which the amplitude of the incoming pulses is 5 volts. A third transistor closes a current path between the first node and the chip's substrate when the substrate voltage is at least one threshold voltage more positive than the first node voltage. As a result, the substrate voltage is driven to a negative level which is about one threshold voltage more positive than the furthest negative voltage level on the first node.

Women in Management Training Programs: What They Think about Key Issues:

Abstract: II.~ y now it is a well knnwn fact that althnugh women in the United Stat\", compose 40% of I the work force, they hold very few of the positions boasting high prestige and high pay. While half the female population, roughly 40 million women, work outside the home, most of them hold low-paying, dead-end \"women's jobs.\" Of today's female workers, 75% are secretaries, household workers, grade-school teachers, bookkeepers, or waitresses.' The work force has tripled since 1940, when 4(;'0 of all executives were women;\" but it is interesting to note that the proportion of women currently holding administrative or management positions is only 5.6%. In fact, one source reports that at the executive level, men outnumber women 600 to I.' According to a recent survey, at least a third of all companies have virtually no women at all in management.' In addition to the fact that women have difficulty landing desirable positions, they also earn less than their male counterparts. In 1977 it was reported that women holding full-time jobs earn an average of $4,800, or 43% less than their male counterparts at $11,800 per year. Twenty years ago the figure was only 36% less.'; The median income for women in 1977 was $8,618 as compared with $14,626 for men.'; In 1978 it was reported that female college graduates earn $9,057 per year, as compared with $15,503 for men. In fact, if women workers were paid equally with men, this would require compensation of $109 billion per year.' While these facts clearly point to obvious differences between the male and female factions of the work force, the underlying reasons are more difficult to come by. Part of the problem resides in stereotyped thinking patterns or myths, which are slow to change, despite evidence contrary to those myths:

Distraction Effects on the Perceived Extremity of a Communication and on Cognitive Responses

Abstract: Participants listened to either a proattitudinal or counterattitudinal communication under varying levels of distraction. A distraction x message position interaction indicated that distraction decreased the perceived extremity of the counterattitudinal communication while increasing the perceived extremity of the proattitudinal message. Distraction decreased the number of counterarguments generated by counterattitudinal speech recipients, but unexpectedly did not significantly affect proargumentation. Proargumentation notwithstanding, the results were consistent with the dominant thought disruption hypothesis.

System-Generated Electromagnetic Pulse and Spacecraft Charging Effects: A Review of the Technology as Applied to System Hardening Problems

Abstract: Investigations of several phenomenological issues remain to be completed. Specifically, for SCC there are the issues of discharge and blowoff from dielectric surfaces, and discharge within PC boards. These subjects are being studied intensely; miscellaneous other issues are also being addressed. At present, SGEMP and SCC phenomena are sufficiently well understood to allow high confidence conservative hardened system designs. These are designs which ulitize extra quantities of rf shielding and other protection techniques to accommodate lack of full understanding of some phenomenological and system coupling/response details. In this regard, additional work is needed in the area of environment/response parameter tradeoff studies to identify hardened system designs that are optomized for minimal weight. Full-scale tests of complex systems very often produce surprise results which reveal flaws in engineering designs or errors in implementation of adequate designs. Closer coordination between hardening technologists and system designers is needed in the future to help minimize such errors. More work is needed on selected hardness assurance and hardness maintainence (HA/HM) issues. It must be determined to what degree the requirement exists that box-level current injection testing for HA/HM be carried out with simultaneous ionizing radiation. In general, greater efforts should be expended in the future to integrate HA/HM testing considerations into system designs. Future trends toward more complex and sophisticated systems will require increasing care in development and implementation of hardened system designs.

A short, efficient analytical satellite theory

Abstract: A simplified analytical solution for the motion of an artificial Earth satellite under the combined influences of the zonal harmonics through J4 and a nonrotating spherically symmetric power density function atmosphere is given. This solution has been obtained by simplification of a more extensive analytical solution previously published by the author. The simplified version has nearly the same accuracy, yet has only about 16% the formula amount of the full theory. Comparison is made with two other widely used simplfied analytical theories of comparable size. Our solution is found to consistently produce equal or superior prediction accuracies. For low-altitude, high-drag satellites, the improvement can approach a factor of 10 or more.

Mass Spectrometric Identification and Confirmation of 16-Methylprednisone Acetate in Mexican Pills

Abstract: The identification and confirmation of an unusual corticosteroid, 16-methylprednisone acetate, in Mexican pills is described. Identification is based on molecular structure illucidation from the electron impact fragmentation pattern. Characteristic m/e peaks at 121 (base peak), 241, 256 and 414 (molecular ion) are observed. Fragmentation pathways leading to these ions are presented. Confirmatory studies, employing NMR are also presented.

Learning through teaching

Abstract: I propose a method of instruction whereby students learn through teaching the material, first to each other and then to members of the wider community.

Electronic Watches and Clocks

Abstract: Publisher Summary This chapter discusses the usage of electronic watches and clock. Electronic watches are inherently reliable. They have essentially no or very few moving parts that are subject to wear. The integrated circuit, the heart of an electronic watch, has also profited from the vast development effort in applications: such as aerospace and computers, where high reliability is essential. Electronic watches are versatile. It is easy to include the additional functions: such as automatic calendar, alarm functions, and stop watch functions that could only be realized with great difficulties in mechanical watches. The impact of the electronic concept on the traditional watch industry that has developed the mechanical watch to perfection over a timespan, that has to be measured in centuries, was very profound. Even so, this revolution is far from being completed watch and clock technology has matured substantially, so that this is an appropriate point in time to review the present status of the electronic watch and assess the trend for future developments.

Connector Contributions to the SGEMP Response of Hardened Cable Systems

Abstract: Measurements of the x-ray induced response of various portions of a low profile multi-pin connnector are presented and compared with model calculations. The conversion of the overbraid/cable shield source term into common mode cable signals that occurs when cable shields are grounded using inductive pigtails is also considered. The various connector contributions are then compared with each other and with contributions from typical hardened cables.

2200°C Fuel Centerline Thermocouples for the Loft Program

Abstract: The technology, as well as commercial suppliers, have been developed for high temperature thermocouples for the Loss-of-Fluid-Test (LOFT)* program. Two types of thermocouples were developed and tested. Model B units contained a 1.6 mm (1/16-inch) O. D., 61 cm (24-inch) long Mo/Re sheath probe and were capable of temperature measurement to 1550°C. Model A units contained 1.6 mm O. D., 104 cm long W/Re-augmented sheath probe and were capable of temperature measurement to 2200°C. Both thermocouples were insulated with sintered HfO2 insulators and contained W/5Re-W/26Re thermoelement wires. Both probe sheaths were terminated with an Al2O3 ceramic-to-metal seal capable of maintaining hermeticity to 10-9 cc He/s during temperature transients to 360°C/ min. at 7.2 MPa (2500 psi) continuous and pressure transients of 2.4 MPa (350 psi)/s at 450°C continuous. The ceramic seal and thermoelement wires were connected by means of a transition assembly to a 7.6 m (25 ft.) length of stainless steel sheath MgO insulated cable for signal transmission to the ex-vessel reactor measurement instrumentation. The thermocouples operated for 1,000 hours at their maximum operating temperatures of 2200°C (model A) and 1550°C (model B) with less than 2% drift in the EMF output. The thermocouples also survived thermal transients of up to 145°C/s with no measureable degredation in measurement performance. The time response of the thermocouples was measured to be less than 2-1/2 seconds at 2000°C and less than 5 seconds at 1500°C. The wire-to-sheath insulation resistance after temperature testing remained >1012 ohms.

A survey and analysis of electrical engineering curricula in communications and signal processing

Abstract: How does one accomplish the task of obtaining and analyzing data in order to describe current trends in a certain segment of electrical engineering education? A year ago, when asked by the Editor of the IEEE Communications Magaine if we thought that the results of such an endeavor dealing with communications and signal processing would be of value to electrical engineering faculty and working communications engineers alike, we struggled with this question. A year later, at the time of writing of this article, we are still struggling with it! In addition to not being sure of just how to analyze and organize the data, we are swamped with more information from a larger sample of electrical engineering departments than we ever dreamed possible. Given this insight into the past andcurrent start of our naivete, then, the readeris asked to acceptht is article at face value - much data, some analysis, and a few inferences. The outline of the paper is simple. We first overview the general conclusions, trends, and implications gained from the survey. We next describe how we gathered the data and how the sample of electrical engineering departments that was used as a data base evolved. Finally, the data on course offerings, textbooks used, areas of research and special investigations, and numbers of students involved are presented along with some discussion of the meaning of the presentations.

Afterbody Pressure Correlations for Vehicles with Ablated Nose Shapes

Abstract: ACORRELATION method is presented for determining the afterbody pressure distributions over the conical afterbodies of slender re-entry vehicles at small angles of attack that have been severely ablated or eroded in the nosetip region. The technique utilizes flowfield solutions for the pressure distributions over symmetrical sphere-cone re-entry vehicles at zero angle of attack. The method is shown to reduce the afterbody pressure data obtained using seven distinctly different nosetip configurations to a single correlation curve. Contents A comprehensive wind tunnel test program to obtain pressure distribution data was conducted at M^ = 8 in tunnel B at the Arnold Engineering Test Center, Arnold Air Force Station, Tenn. The baseline sphere-cone model which was tested was a 6.7-deg half-angle conical afterbody with a bluntness ratio (RN/RB) of 0.227. The seven nose configurations shown in Fig. 1 were tested and the nose attachment plane was located at body station X/L = 0.173. The pressure data from the present experiments were correlated using the axial distance parameter (CPc /^Tc~A N . XS/DN) suggested by Mirels and Thornton1 and a pressure parameter, CP/CP where CP is the sharp cone pressure, DN is the diameter of the nose, CAN is the nose axial force coefficient referenced to the nose base area, and Xs is the axial distance from the nosetip sonic point. The experimental pressure data for each of the ablated nosetips is correlated against the spherical nosetip data in Fig. 2, using the modified distance parameter. The pressure parameter was not utilized in this exercise since experimental data were available for only one cone angle. It can be seen from the plot that the axial distance correlation parameter has quite effectively collapsed the afterbody pressure data that were obtained with rather diverse nose shapes to the correlation curve obtained for the spherical nose. The pressures in the region less than one nose diameter from the nosetip are not well correlated. The experimental results previously presented clearly indicate that reasonable afterbody pressure distributions for vehicles with severely ablated nosetips can be obtained from sphere-cone pressure distributions. The a = 0 pressure distribution along the length of a spherecone re-entry vehicle with a cone half-angle of 6.7 deg was calculated for M00=8, using the Rakich2 method of characteristics solution, out to a distance of 160 nose radii

A short, efficient analytical satellite theory

Abstract: A simplified analytical solution for the motion of an artificial Earth satellite under the combined influences of the zonal harmonics through J4 and a nonrotating spherically symmetric power density function atmosphere is given. This solution has been obtained by simplification of a more extensive analytical solution previously published by the author. The simplified version has nearly the same accuracy, yet has only about 16% the formula amount of the full theory. Comparison is made with two other widely used simplfied analytical theories of comparable size. Our solution is found to consistently produce equal or superior prediction accuracies. For low-altitude, high-drag satellites, the improvement can approach a factor of 10 or more.