Showing papers by "RAND Corporation published in 1972"

Bilingualism and cognitive development.

Abstract: IANCO-WORRALL, ANITA D. Bilingualism and Cognitive Development. CHILD DEVELOPMENT, 1972, 43, 1390-1400. Limited to one definition of bilingualism, namely, dual-language acquisition, in a one-person, one-language home environment, experiments were designed to test Leopold's observations on the earlier separation of word sound from word meaning by bilingual compared to matched unilingual children. Attention to meaning or to sound of words was tested with the semantic and phonetic preference test, a two-choice test in which similarity between words could be interpreted on the basis of shared meaning or shared acoustic properties. The notion that bilingualism leads to the earlier realization of the arbitrary nature of name-object relationship was tested with the questioning technique described by Vygotsky. This called for the explanation of names, whether names can be interchanged and, when names are interchanged in play, whether the attributes of the objects change along with their names. The results support Leopold's observation on the earlier separation of sound and meaning by bilingual children.

Limiting the Risk of Bayes and Empirical Bayes Estimators—Part II: The Empirical Bayes Case

Abstract: We discuss compromises between Stein's estimator and the MLE which limit the risk to individual components of the estimation problem while sacrificing only a small fraction of the savings in total squared error loss given by Stein's rule. The compromise estimators “limit translation” away from the MLE. The calculations are pursued in an empirical Bayesian manner by considering their performance against an entire family of prior distributions on the unknown parameters.

Empirical Bayes on vector observations: An extension of Stein's method

Abstract: SUMMARY The statistician is considering several independent normal linear models with identical structures, and desires to estimate the vector of unknown parameters in each of them. An estimator is constructed which dominates the usual Gauss-Markov estimator in terms of total squared error loss. This estimator is shown to have good efficiency in the Bayesian situation where the parameter vectors themselves have a normal prior distribution. A practical example is given.

A class of low-rate nonlinear binary codes

Abstract: This paper introduces a new class of nonlinear binary codes. For each l = 2, 3,… we present a code with 2 41 codewords of length N = 4 l and distance d = (4 l — 2 l )/2. Each code is a supercode of the 1st-order Reed-Muller (RM) code and a subcode of the 2nd-order RM code. These codes are the “duals≓ of the extended nonlinear Preparata codes in the sense that their weight distributions satisfy the MacWilliams identities.

Response Areas for Two Emergency Units

Abstract: This paper gives a model in which two urban emergency service units such as fire engines or ambulances cooperate in responding to alarms or calls from the public in a specified region of a city. Given the home locations of the units and the spatial distribution of alarm rates, it is possible to specify which unit should respond to each alarm by defining a response area for each unit. The average response time to alarms and the workload of each unit are calculated as functions of the boundary that separates their response areas. The boundaries that minimize average response time and the ones that equalize workload are determined. Some boundaries can be dominated, in the sense that another boundary improves both workload balance and response time. The set of undominated boundaries is found.

On Balanced Games Without Side Payments

Abstract: Publisher Summary This chapter presents a new proof of a basic theorem of game theory, because of Scarf, that states that every balanced game without side payments has a nonempty core. The main tool is a new generalization of Sperner's celebrated topological lemma concerning triangulations of the simplex, which will be of independent interest. The chapter describes balanced sets and provides the simple but very useful geometric characterization of these sets. It also describes iterated barycentric partitions.

Methods for Allocating Urban Emergency Units: A Survey

Abstract: An urban emergency service system provides mobile units vehicles to respond to requests for service which can occur at any time and any place throughout a city. This paper describes the common characteristics and operational problems of these systems and surveys the various methods, both traditional and recently developed, which may be used for allocating their units. Aspects of allocation policy discussed include 1 determining the number of units to have on duty, 2 locating the units, 3 designing their response areas or patrol areas, 4 relocating units, and 5 planning preventive-patrol patterns for police cars. Typical policy changes which may be suggested by the use of quantitative allocation models include selective queuing of low priority calls, varying the number of units on duty and their locations by time of day, dispatching units other than the closest ones to certain incidents, relocating units as unavailabilities begin to develop, and assigning police cars to overlapping patrol sectors. As a result of making such changes, it is often possible to reduce queuing and travel time delays, improve the balance of workload among units, and enhance the amount of preventive patrol where needed.

Minimal scrambling sets of simple orders

Abstract: : Let 2 < or = k < n be fixed integers, a family F of simple orders on an n element set is said to be k-suitable if of every k elements in the n set, each one is the largest of the k in some simple order in F. Bounds are found on the minimal size of such an F. F is said to be k star-suitable if for every k elements in the n-set each permutation of the k elements is realized in some simple order in F. Again bounds are found on the minimal size of such an F. (Author)

Mariner 9 Television Reconnaissance of Mars and Its Satellites: Preliminary Results

Abstract: At orbit insertion on 14 November 1971 the Martian surface was largely obscured by a dust haze with an extinction optical depth that ranged from near unity in the south polar region to probably greater than 2 over most of the planet. The only features clearly visible were the south polar cap, one dark, spot in Nix Olympica, and three dark spots in the Tharsis region. During the third week the atmosphere began to clear and surface visibility improved, but contrasts remained a fraction of their normal value. Each of the dark spots that apparently protrude through most of the dust-filled atmosphere has a crater or crater complex in its center. The craters are rimless and have featureless floors that, in the crater complexes, are at different levels. The largest crater within the southernmost spot is approximately 100 kilometers wide. The craters apparently were formed by subsidence and resemble terrestrial calderas. The south polar cap has a regular margin, suggesting very flat topography. Two craters outside the cap have frost on their floors; an apparent crater rim within the cap is frost free, indicating preferential loss of frost from elevated ground. If this is so then the curvilinear streaks, which were frost covered in 1969 and are now clear of frost, may be low-relief ridges. Closeup pictures of Phobos and Deimos show that Phobos is about 25 ±5 by 21 ±1 kilometers and Deimos is about 13.5 ± 2 by 12.0 ±0.5 kilometers. Both have irregular shapes and are highly cratered, with some craters showing raised rims. The satellites are dark objects with geometric albedos of 0.05.

The flow and stability of thin liquid films on a rotating disk

Abstract: Measurements of the thickness and the stability of thin films of liquid (1–150 μmthick) formed on a rotating horizontal disk are presented and correlated in terms of an asymptotic-expansion solution of the thin-film equations. Water, various alcohols and water with wetting activities were used to cover a range of viscosity (1-2.5cP) and surface tension (20-72 dynes/cm). Smooth flow was found to occur in a region defined by the flow rate, rotational speed and physical properties of the liquid. Outside this region various wave patterns were observed (concentric, spiral and irregular waves). A linear theory of the stability of the film based on an extension of classical stability theories for plane films on inclined planes is given and contrasted with the experimental results. Surface phenomena associated with the use of wetting agents were found to have a strong effect on the stability of the film.

The ultimate computer

Abstract: A distant relative left you an inheritance of $3000. The catch is it must be used to purchase a computer and software products for help in your future endeavors. Your parents have decided to leave you in charge of selecting .They know that you have been taking a computer class and have been working with computers for a very long time. You need to justify your selection and educate them as to what all the 'tech specs' are for the computer you wish. You are to create a powerpoint presentation that will 'sell' your parents on your choice. Think about what you want to do with your computer. As you research your selection think about what needs you have. Do you want to create videos? Work with Photoshop? Or just use myspace? There is a budget to work with, but your parents understand the importance of staying up to date with technology. Research and explain to your parents all you can about the following: 1. A PC vs. Mac. Which one? Is one better than the other, why? 2. CPU – central processing unit 3. Memory – RAM 4. Hard Drive – size of it? Speed? 5. Optical drive – cd vs. dvd vs. blu-ray. Which is best for me? What's the difference? 6. Monitor 7. Video Card 8. Sound Card 9. Floppy drive? 10. Network – NIC, router / modem – to connect to other computers / internet 11. USB 12. Wireless possibilities 13. Software – gaming, virus protection, Microsoft office, Adobe, others from class? 14. Printer – one for photos? Regular inkjet or laserjet? 15. Peripherals – digital camera, Ipod, scanner, etc Rubric to follow soon. Quiz on the terms above, be ready! It will take place on your final 

Metal detector system having identical balanced field coil system on opposite sides of a detection zone

Abstract: A balanced field metal detector apparatus comprising a coil assembly including planar, generally rectangular loop configured multi-turn field and sensor coils disposed in partially overlapping minimum mutual inductive coupling relation and oriented so that the long dimension of the loops is skewed relative to the vertical in use of the apparatus. Employment of a pair of the detectors, one on each side of a pathway, with the respective coil assemblies skewed relative to the vertical oppositely to one another, enables detection of a metal object in the pathway by one or both of the detectors irrespective of the shape and orientation of the object, and by suitable processing of the sensor coil signals further enables determination of whether the object is located at the left, center or right side of the pathway.

The real time system

Abstract: The Real Time System described herein was designed and implemented for the purpose of serving Univa c Management at all levels with an inquiry/response, updat e and data collection tool fitting the precise requirements o f the Company . The system was not intended to be offere d as a generalized software package . The system runs on the 1108 Computer installed a t Univac Headquarters in Blue Bell, Pennsylvania . Exec VII I Level 27 is currently employed . Further details relative t o the hardware configuration are provided by the attache d chart . There were several elements considered in the initia l design of the system . These elements may be divided int o three categories : User considerations, programming considerations, and operational considerations .

Applications of Time-Domain Metrology to the Automation of Broad-Band Microwave Measurements

Abstract: It is only recently that measurement of the transient response of microwave systems directly in the time domain has become practicable. It has led to growing interest in the concept of specifying broad-band performance solely by a transient-response measurement. Results of the use of time-domain techniques to obtain, within the range 0.1 to 10 GHz, such data as the S parameters of networks, the constitutive parameters of microwave materials, the driving-point impedance and transfer function of microwave antennas, and the frequency-domain scattering parameters of conducting surfaces in free space are described.

A New Approach to the Index Number Problem

Abstract: A. Introduction, 188. — B. The theoretical basis of the index, 189. — C. The price and quantity index defined, 194. — D. Structural price and quantity differences, 199. — E. A measure of significance, 200. — F. The comparison of more than two aggregates, 202. — Appendices: I. A. comparison of my estimates of Gross National Product for the Soviet Union and Western Europe with previous estimates, 205. — II A note on the factor reversal test, 205. — III. Iteration-convergence problem, 206. — IV. A numerical illustration of computing the quantity index, 210.

Digital filters for sample-rate reduction

Abstract: The design of bandwidth-limiting filters for the purpose of sample-rate reduction is considered. Realization of linear-phase finite-duration impulse-response (FIR) filters for this application by direct convolution is shown to be more efficient than the recursive realization [1]. The degree to which the Nyquist rate (relative to the desired signal bandwidth) must be exceeded at the filter output in order to avoid aliasing is suggested as a measure of filter effectiveness. Direct convolution is faster than the fast convolution for FIR equiripple [2] filters designed to operate within 10 percent of the Nyquist rate with 60- to 70-dB stopband attenuation at a 2:1 sample-rate reduction. This advantage improves with the log of the sample-rate reduction ratio. Several comparisons made with recursive realizations of elliptic filters give the advantage to direct convolutional realization of FIR filters for sampling within about 20 percent of the Nyquist rate at 60- to 70-dB attenuation. Elliptic filters become more efficient at higher complexities (of about eight poles and eight zeros). Two design techniques that exploit the reduced output sample rate in the design of FIR filters by direct convolution are suggested. The effects of quantization of FIR filter coefficients on the frequency response are considered and several examples illustrated.

Aircraft automatic flight control system

Abstract: An automatic flight control system for aircraft providing improved aircraft response to input displacement commands, especially of the generally step input type, in a simple and economical manner; and further providing an improved yet economical control wheel steering capability. An improved automatic pilot electric surface servomotor system is also disclosed. Smooth and consistent roll acceleration limiting to step-like or abrupt roll attitude displacement commands are provided by rate limiting the displacement signal and then passing the limited signal through a simple lag filter having a predetermined time constant. Control wheel steering is available to the pilot by means of a wheel mounted switch which, when actuated, declutches the autopilot servoes, synchronizes the autopilot references during manual maneuvering through the aircraft manual control mechanism and, upon release of the switch re-establishes any preselected vertical path mode and/or establishes a roll attitude hold mode. Operation of CWS switch may be used to override various autopilot limits and upon release of switch maintains the overridden limit attitude; the autopilot automatically re-establishing automatic flight path demand control when the path demand signal equals the attitude limit established by the human pilot during control wheel steering. The autopilot surface servomotor control loop is characterized by an improved apparatus for limiting the torque output thereof by providing current feedback to the servo amplifier.

Illuminating light blending makeup mirrors and electrical control circuit

Abstract: A plurality of incandescent lamps and one or more makeup mirrors are incorporated in a portable case. Some of the lamps are unfiltered, the others are provided with red filters. The red filtered lamps are all connected in parallel. The white lamps are also connected in parallel, and the two sets of parallel lamps are connected in series across a source of 110 volts alternating current. The high and common terminals of a bidirectional gate control thyristor are connected in parallel across the set of red lamps. A variable resistor and a capacitor are connected in series, and the RC circuit thus formed is connected in parallel across the set of red lamps. A triggering diode is connected between the gate terminal of the thyristor and the common terminal between the variable resistor and capacitor. The triggering diode is preferably incorporated into the same integrated circuit as the bidirectional gate control thyristor. The white incandescent lamps may be provided with light absorbing filters in order to balance the intensities of the two sets of lamps.

Multifrequency communication system for fading channels

Abstract: A communication system particularly for underwater communication includes a transmitter and a receiver. An oscillator in the transmitter generates a plurality of signals each having a unique frequency. A network selects predetermined combinations of signals from this plurality, each selected combination defining a data symbol to be transmitted. The assignment of the frequency groups with respect to the data symbols to be transmitted is achieved via a Hadamard matrix. During each data symbol transmission interval a gate selects the combination of frequency signals corresponding to the symbol to be transmitted. The signals in the combination are added and transmitted by a transducer. The receiver includes a bank of filters each tuned to one of the plurality of frequency signals generated in the oscillator bank. The outputs of the filters are envelope detected and applied to a frequency code selector. In each data symbol transmission interval, the frequency code selector combines the detected outputs from the filter bank in accordance with the Hadamard transformation matrix to provide a plurality of groups of signals each corresponding to a symbol in the system symbol repertoire. Each group of signals are summed and the resulting signals applied to a decision circuit that selects the maximum therefrom. The output of the decision circuit which is representative of the transmitted symbol is applied to a suitable readout.

Vehicular safety system

Abstract: A vehicular safety apparatus includes radio sensor means for the detection of an impending collision immediately prior to contact of the protected vehicle with another object and for actuation of restraining or other safety devices for protecting occupants of the vehicle when the crash event actually occurs. Base-band radio pulse transmission and reception presence sensor devices with first and second zone echo signal gating channels provide distinctive output signals at first and second distances between the protected vehicle and the reflecting object, which signals when present simultaneously cause actuation of the protective devices.

Fluid operated contaminant trap

Abstract: A dynamic filter for removing ultra fine particles in a stream of fluid has a cylindrical rotor powered by the energy in a stream of fluid. The stream is directed through a centrifugal pump and through a turbine. Axial passages connect between them. The outer walls of the axial passages are constituted by a scrim, forming an absorbent for contaminant particles driven into the absorbent material by centrifugal force.

The relative importance of contrast and motion in visual detection.

Abstract: : Results of a previous study (see AD-720 800) suggested that the effect of motion on detecability might be caused entirely by contrast changes as the target moves over a complex background. The test documented in the present study, employing a television display and an artificial background, showed independent effects of both contrast and motion on target detectability. The effects can be accounted for by modifying the exponent in the detection probability function with a linear contrast term and a second-power velocity term. Single-fixation experiments confirmed a larger aperture for moving targets than for static targets, and also demonstrated a gradual increase in the fixation time required to detect a target as a function of its distance from the fixation point. (Author)