Showing papers by "Purdue University published in 1979"

Ubiquitous B-Tree

Abstract: B-trees have become, de facto, a standard for file organization. File indexes of users, dedicated database systems, and general-purpose access methods have all been proposed and nnplemented using B-trees This paper reviews B-trees and shows why they have been so successful It discusses the major variations of the B-tree, especially the B+-tree, contrasting the relatwe merits and costs of each implementatmn. It illustrates a general purpose access method whmh uses a B-tree.

Consequences of individual feedback on behavior in organizations.

Abstract: The literature on feedback to individuals was reviewed with respect to its effect on the behavior of individuals in performance-o riented organizations. Although contemporary views of individual behavior in organizations stress that feedback is necessary for effective role performance, little attention is given to the psychological processes affected by it. This review focuses upon the multidimensional nature of feedback as a stimulus and addresses the process by which feedback influences behavior. Emphasis is placed on those aspects of feedback that influence (a) the way it is perceived, (b) its acceptance by the recipient, and (c) the willingness of the recipient to respond to the feedback. Feedback about the effectiveness of an individual's behavior has long been recognized as essential for learning and for motivation in performance-oriented organizations. Not surprisingly, considerable research has been conducted on the subject (see reviews of feedback by Adams, 1968; Ammons, 19S6; Annett, 1969; Bilodeau, 1966; Locke, Cartledge, & Koeppel, 1968; Sassenrath, 1975). Yet, in spite of the large and varied literature, generalizations about the effects of feedback on individuals are few. Several factors contribute to this state of affairs. First, feedback is not a simple stimulus. The diverse elements subsumed under the single rubric of feedback may share the property of conveying some degree of information about past behavior, but they share We wish to thank L. L. Cummings, H. P. Dachler, E. A. Locke, M. M. Greller, D. M. Herold, and J. C. Naylor for their helpful comments on an earlier draft of this article. The research was supported by Grant DAHC 19-76-G-0017 from the Army Research Institute for the Behavioral Sciences, as part of the technical-base research project for the Organizational Development Unit. While the support of the agency is greatly appreciated, the ideas expressed in the article are solely those of the authors and are not to be considered the position of the agency or the U.S.

Circumplex Model of Marital and Family Systems: I. Cohesion and Adaptability Dimensions, Family Types, and Clinical Applications

Abstract: The conceptual clustering of numerous concepts from family therapy and other social science fields reveals two significant dimensions of family behavior, cohesion and adaptability. These two dimensions are placed into a circumplex model that is used to identify 16 types of marital and family systems. The model proposes that a balanced level of both cohesion and adaptability is the most functional to marital and family development. It postulates the need for a balance on the cohesion dimension between too much closeness (which leads to enmeshed systems) and too little closeness (which leads to disengaged systems). There also needs to be a balance on the adaptability dimension between too much change (which leads to chaotic systems) and too little change (which leads to rigid systems). The model was developed as a tool for clinical diagnosis and for specifying treatment goals with couples and families.

A fast two-dimensional median filtering algorithm

Abstract: We present a fast algorithm for two-dimensional median filtering. It is based on storing and updating the gray level histogram of the picture elements in the window. The algorithm is much faster than conventional sorting methods. For a window size of m × n, the computer time required is 0(n).

Image Compression Using Block Truncation Coding

Abstract: A new technique for image compression called Block Truncation Coding (BTC) is presented and compared with transform and other techniques The BTC algorithm uses a two-level (one-bit) nonparametric quantizer that adapts to local properties of the image The quantizer that shows great promise is one which preserves the local sample moments This quantizer produces good quality images that appear to be enhanced at data rates of 15 bits/picture element No large data storage is required, and the computation is small The quantizer is compared with standard (minimum mean-square error and mean absolute error) one-bit quantizers Modifications of the basic BTC algorithm are discussed along with the performance of BTC in the presence of channel errors

The Statistical Nature of Fatigue Crack Propagation

Abstract: : A statistical investigation of the fatigue crack propagation process was conducted. Sixty-eight replicate constant amplitude crack propagation tests were conducted on 2024-T3 aluminum alloy. The following distributions were considered: two-parameter normal distribution, three-parameter log-normal distribution, three-parameter Weibull distribution, two-parameter gamma distribution, three-parameter gamma distribution, the generalized three- parameter gamma distribution, and the generalized four-parameter gamma distribution. From the experimental data, the distribution of N as a function of crack length was best represented by the three-parameter log-normal distribution. Six growth rate calculation methods were investigated and the method which introduced the least amount of error into the growth rate data was found to be a modified secant method. Based on the distribution of da/dN, which varied moderately as a function of crack length, replicate a vs. N data were predicted. This predicted data reproduced the mean behavior but not the variant behavior of the actual a vs. N data.

LP Bounds of solutions of reaction-diffusion equations

Abstract: (1979). LP Bounds of solutions of reaction-diffusion equations. Communications in Partial Differential Equations: Vol. 4, No. 8, pp. 827-868.

Error-Correcting Isomorphisms of Attributed Relational Graphs for Pattern Analysis

Abstract: The pattern deformational model proposed by Tsai and Fu [11] is extended so that numerical attributes and probability or density distributions can be introduced into primitives and relations in a nonhierarchical relational graph. Conventional graph isomorphisms are then generalized to include error-correcting capability for matching deformed patterns represented by such attributed relational graphs. An ordered-search algorithm is proposed for determining error-correcting isomorphisms. Finally, a pattern classification approach using graph isomorphisms is described, which can be considered as a combination of structural and statistical techniques.

Effect of earth's rotation on the quantum mechanical phase of the neutron

Abstract: Using a neutron interferometer of the type first developed by Bonse and Hart for x rays, we have observed the effect of Earth's rotation on the phase of the neutron wave function. This experiment is the quantum mechanical analog of the optical interferometry observations of Michelson, Gale, and Pearson.

An Approximation Theory of Optimal Control for Trainable Manipulators

Abstract: A theoretical procedure is developed for comparing the performance of arbitrarily selected admissible controls among themselves and with the optimal solution of a nonlinear optimal control problem. A recursive algorithm is proposed for sequential improvement of the control law which converges to the optimal. It is based on the monotonicity between the changes of the Hamiltonian and the value functions proposed by Rekasius, and may provide a procedure for selecting effective controls for nonlinear systems. The approach has been applied to the approximately optimal control of a trainable manipulator with seven degrees of freedom, where the controller is used for motion coordination and optimal execution of object-handling tasks.

Neurites grow faster towards the cathode than the anode in a steady field.

Abstract: We explanted fragments of embryonic chick dorsal root ganglia on to polylysine coated glass and cultured them in a medium containing one unit of nerve growth factor plus enough methylcellulose to give viscosities from 0.01-3,000 poise. We allowed them to grow out in the absence of a field, and then selected explants with halos of neurites which were relatively dense, relatively symmetrical, and practically free of glial cells. These selected explants were then exposed to electrical fields of up to 140 mV/mm for some hours. In media with viscosities of one poise or less, the field some times dragged the central cell mass of an explant towards the anode. However, in cases where the central cell mass did not move, fields of 70-140 mV/mm induced that sector of each neurite halo which faced the cathode to grow out several times faster than the one facing the anode.

Computerized tomography with X-ray, emission, and ultrasound sources

Abstract: This paper reviews the major developments that have taken place during the last three years in imaging with computed tomography (CT) using X-ray, emission, and ultrasound sources. Space limitations have resulted in some selection of topics by the author. There are four major sections dealing with algorithms, X-ray CT, emission CT, and ultrosound CT. Since most of the currently used algorithms are of filtered-backprojection type, we have concentrated on these in the section on algorithms (with emphasis on their implementation aspects). In X-ray CT an important question raised during the last few years has concerned the parameter measured by a CT scanner, given the fact that the X-rays used in CT scanners are polychromatic and the fact that tissue attenuation coefficients are energy dependent. Answers to this question are reviewed in the section on X-ray CT where we have also discussed the artifacts caused by the polychromaticity of the X-ray photons. Methods for the removal of these artifacts have also been reviewed. In emission CT the biggest development of the last three years is the great interest in positron tomography, although space constraints have dictated an essentially introductory treatment and not all aspects of the single photon and positron tomography have been surveyed. Finally, we have reviewed recent developments in ultrasound CT. We have pointed out that because of the sensitivity of this technique to refraction, it is currently limited to soft tissue structures, with ultrasonic detection of tumors in the female breast a significant application.

Characteristics of Tornado-Like Vortices as a Function of Swirl Ratio: A Laboratory Investigation

Abstract: The investigation of tornado vortex dynamics by means of a laboratory simulation is described. Based on observations from nature and an examination of the Navier-Stokes equations, a laboratory simulator of the Ward type has been constructed. This simulator generates various vortex configurations as a function of swirl ratio, radial Reynolds number and aspect ratio. Configurations which are described are 1) a single laminar vortex; 2) a single vortex with breakdown bubble separating the upper turbulent region from the lower laminar region; 3) a fully developed turbulent core, where the breakdown bubble penetrates to the bottom of the experimental chamber; 4) vortex transition to two intertwined helical vortices; and 5) examples of higher order multiple-vortex configurations that form in the core region. Hot-film anemometry measurements of the magnitude of the velocity vector and inflow (swirl) angle have been obtained in a sequence of flows characterized by progressively increasing values of swirl...

Bayesian estimation and optimal designs in partially accelerated life testing

Abstract: A method of life testing is proposed which combines both ordinary and accelerated life-testing procedures. It is assumed that an item can be tested either in a standard environment or under stress. The amount of stress is fixed in advance and is the same for all items to be tested However, the time x at which an item on lest is taken out of the standard environment and put under stress can be chosen by the experimenter subject to a given cost structure. When an item is put under stress its lifetime is changed by the factor α. Let the random variable T denote the lifetime of an item in the standard environment, and let γ denote its lifetime under the partially accelerated test procedure just described. Then Y = T if T ≦ x, and Y = x + α (T > x) if T > x. It is assumed that T has an exponential distribution with parameter θ. The estimation of θ and α and the optimal design of a partially accelerated life test are studied in the framework of Bayesian decision theory.

Source of antioxidant activity of soybeans and soy products

Abstract: Soybeans, defatted soy flour, soy protein concentrates, and soy isolates possess appreciable antioxidant activity in lipid-aqueous systems. The antioxidant properties of soybeans, defatted soy flour, and soy protein concentrates are due primarily to polyphenolic compounds. Antioxidant activity of soy protein isolates are also due to polyphenolic compounds but other compounds also exert a marked antioxidant effect. Polyphenolic antioxidants of soy were found to be isoflavones, chlorogenic acid isomers, caffeic acid, and ferulic acid. These compounds occurred primarily as glycosides. The isoflavone aglycones were identified as genistein (5,7,4′-trihydroxyisoflavone), daidzein (7,4′-dihydroxyisoflavone), and glycitein (7,4′-dihydroxyd-methoxyisoflavone. The compounds have antioxidant activity but not to the same extent as flavonoids with the dihydroxy configuration in either the α or β ring.

Natural H + Currents Traverse Growing Roots and Root Hairs of Barley ( Hordeum vulgare L.)

Abstract: With the aid of an extracellular vibrating electrode, natural electric fields were detected and measured in the medium near growing roots and root hairs of barley seedlings. An exploration of these fields indicates that both the root as a whole, as well as individual root hairs, drive large steady currents through themselves. Current consistently enters both the main elongation zone of the root as well as the growing tips of elongating root hairs; it leaves the surface of the root beneath the root hairs. These currents enter with a density of about 2 microamperes per square centimeter, leave with a density of about 0.5 to 1 microampere per square centimeter, and total about 30 nanoamperes. Responses of the natural fields to changes in the ionic composition of the medium as well as observations of the pH pattern in the medium near the roots (made with bromocresol purple) together indicate that much of the current consists of hydrogen ions. Altogether, H + ions seem to leak into growing cells or cell parts and to be pumped out of nongrowing ones.

Data Security

Abstract: The rising abuse of computers and increasing threat to personal privacy through data banks have stimulated much interest in the technical safeguards for data. There are four kinds of safeguards, each related to but distinct from the others. Access controls regulate which users may enter the system and subsequently which data sets an active user may read or write. Flow controls regulate the dissemination of values among the data sets accessible to a user. Inference controls protect statistical databases by preventing questioners from deducing confidential information by posing carefully designed sequences of statistical queries and correlating the responses. Statistical data banks are much less secure than most people believe. Data encryption attempts to prevent unauthorized disclosure of confidential information in transit or in storage. This paper describes the general nature of controls of each type, the kinds of problems they can and cannot solve, and their inherent limitations and weaknesses. The paper is intended for a general audience with little background in the area.

Query Processing in Distributed Database System

Abstract: Query processing in a distributed system requires the transmission f data between computers in a network. The arrangement of data transmissions and local data processing is known as a distribution strategy for a query. Two cost measures, response time and total time are used to judge the quality of a distribution strategy. Simple algorithms are presented that derive distribution strategies which have minimal response time and minimal total time, for a special class of queries. These optimal algorithms are used as a basis to develop a general query processing algorithm. Distributed query examples are presented and the complexity of the general algorithm is analyzed. The integration of a query processing subsystem into a distributed database management system is discussed.

Dehydration of Ethanol: New Approach Gives Positive Energy Balance

Abstract: Water was removed from aqueous ethanol by using cellulosic materials, starch, corn, and other agents. The combustion energy of the ethanol product can exceed the energy needed to carry out the dehydration by a factor of 10.

The tracker: a threat to statistical database security

Abstract: The query programs of certain databases report raw statistics for query sets, which are groups of records specified implicitly by a characteristic formula. The raw statistics include query set size and sums of powers of values in the query set. Many users and designers believe that the individual records will remain confidential as long as query programs refuse to report the statistics of query sets which are too small. It is shown that the compromise of small query sets can in fact almost always be accomplished with the help of characteristic formulas called trackers. Schlorer's individual tracker is reviewed; it is derived from known characteristics of a given individual and permits deducing additional characteristics he may have. The general tracker is introduced: It permits calculating statistics for arbitrary query sets, without requiring preknowledge of anything in the database. General trackers always exist if there are enough distinguishable classes of individuals in the database, in which case the trackers have a simple form. Almost all databases have a general tracker, and general trackers are almost always easy to find. Security is not guaranteed by the lack of a general tracker.

Low-dc-field susceptibility of Cu Mn spin glass

Abstract: Low-dc-field magnetic-susceptibility measurements are reported for $\mathrm{Cu}\mathrm{Mn}$ alloys containing 1.08- and 2.02-at.% Mn using a superconducting quantum-interference device. The zero-field cooled initial susceptibility shows a cusplike peak at ${T}_{g}$, the transition temperature to a spin-glass state. After field cooling from $Tg{T}_{g}$ (even for $H=2$ G), the susceptibility below ${T}_{g}$ is nearly independent of temperature with the constant value of $\ensuremath{\sim}0.97\ensuremath{\chi}({T}_{g})$. The high-temperature susceptibility follows a Curie-Weiss law until just above ${T}_{g}$; the value of the Curie temperature is very small. Using the theory of Sherrington and Kirkpatrick, the spin-glass order parameter $q(T)$ is extracted from the susceptibility data. A critical index $\ensuremath{\beta}\ensuremath{\simeq}1$ is obtained assuming a power law for $q(T)\ensuremath{\propto}{(1\ensuremath{-}\frac{T}{{T}_{g}})}^{\ensuremath{\beta}}$. The results are qualitatively in agreement with the prediction of an Edwards-Anderson-type mean-field theory.