Showing papers by "RAND Corporation published in 1976"

A Model for the Thermodynamic Growth of Sea Ice in Numerical Investigations of Climate

Abstract: A model is presented whereby the thickness and extent of sea ice may be predicted in climate simulations. A basic one-dimensional diffusion process is taken to act in the ice, with modifications due to penetration of solar radiation, melting of internal brine pockets, and accumulation of an insulating snow cover. This formulation is similar to that of a previous study by Maykut and Untersteiner, but the introduction of a streamlined numerical method makes the model more suitable for use at each grid point of a coupled atmosphere-ocean model. In spite of its simplicity, the ice model accurately reproduces the results of Maykut and Untersteiner for a wide variety of environmental conditions. In 25 paired experiments, annual average equilibrium thicknesses of ice agree within 24 cm for 75% of the cases; and the average absolute error for all cases is 22 cm. The new model has fewer computational requirements than one layer of ocean in the polar regions, and it can be further simplified if additional ...

Implementation of Educational Innovation

Abstract: (1976). Implementation of Educational Innovation. The Educational Forum: Vol. 40, No. 3, pp. 345-370.

Modeling the Ice-Age Climate

Abstract: Using the boundary conditions of seasurface temperature, ice sheet topography, and surface albedo assembled by CLIMAP for 18,000 B.P., the global ice-age July climate has been simulated with a two-level dynamical atmospheric model. Compared with the simulation for present July climate, the ice age is substantially cooler and drier over the unglaciated continental areas, with the maximum zonal westerlies in the Northern Hemisphere displaced southward in the vicinity of the ice sheets. The simulated changes of surface air temperature agree reasonably well with the estimates available from the analysis of fossil pollen and periglacial data, and are consistent with the simulated changes of other climatic variables. These results are generally supported by independent investigations with simpler models. In spite of this qualified success, further analysis of both simulated and verification data is needed to establish the details of ice-age climate, especially the precipitation regimes, and to document the role of eddy fluxes in maintaining the heat, momentum, and moisture balances of the ice-age general circulation. New paleoclimatic data bases for both July and January of 18,000 B.P. are being assembled by CLIMAP and will be used in new simulations of the seasonal ice-age climate.

The Numerical Simulation of Ice-Age Climate with a Global General Circulation Model.

Abstract: The global distribution of July climate has been simulated with a two-level atmospheric general circulation model using the surface boundary conditions of sea-surface temperature, ice-sheet topography and surface albedo assembled by CLIMAP for 18 000 years before present. These conditions respresent an approximate doubling of the ice-covered surface area of the earth, a 1°C decrease of the average sea-surface temperature, and an increase of the average surface albedo from 0.14 to 0.22. Compared with the simulation of present July conditions, the ice-age atmosphere is found to have been substantially cooler and drier, especially over the continents of the Northern Hemisphere, corresponding to an enhanced anticyclonic circulation over the major ice sheets and a general weakening of the summer monsoonal circulation. The midlatitude westerlies are strengthened and systematically displaced southward in the vicinity of the major ice sheets, along with an equatorward shift in the zones of maximum eddy a...

Monthly Average Sea-Surface Temperatures and Ice-Pack Limits on a 1 degree Global Grid

Abstract: Climatological monthly ocean-surface temperatures obtained from the National Center for Atmospheric Research and from Fleet Numerical Weather Central are merged and interpolated onto a 1° global grid. Monthly distributions of the main ice packs of the Arctic and Antarctic are digitized from Fleet Weather Facility ice charts and Navy atlases, and are incorporated into the global arrays. Machine-analyzed maps of the resulting distributions for the months of January, March, May, July, September and November are presented to indicate the seasonal variations of temperature and ice extent.

Differences between Return and Nonreturn Migration: An Econometric Analysis:

Abstract: : The regression equations presented in this report furnish strong and consistent indications that potential return and nonreturn migrants respond quite differently to the factors that condition migration decisions. The importance of treating return and nonreturn migration separately, and recognizing their differences in theories of human migration is underscored. Despite admittedly crude data and some necessary approximations, these differences show through with notable consistency, suggesting that the true underlying relationships may be quite strong. This exercise should be repeated using data that permit a more exact delineation of return migration--for example, residence histories supplemented with information on contemporaneous economic conditions during the reference period. A second notable finding--that return migration probabilities are positively (and significantly) related to distance warrants further investigation with independent data. Finally, this investigation should be extended to other age-sex groups.

Ice-Bearing Cumulus Cloud Evolution: Numerical Simulation and General Comparison Against Observations.

Abstract: A two-dimensional (axisymmetric) numerical cloud model with parameterized microphysics for water drops and ice particles is described. The parameterized liquid-phase processes include condensation, evaporation, autoconversion of small drops to large ones, and collection of small drops by large ones. The solid-phase processes include heterogeneous sorption nucleation, homogeneous contact nucleation, deposition, sublimation, riming and melting. Both liquid and solid particles may precipitate. The model was used to simulate three different conditions of ice generation as a function of temperature: 1) based on classical concepts of the activity of heterogeneous ice-forming nuclei—suggesting continental cumuli; 2) based on field observations of much greater concentrations of ice particles at warmer temperatures than indicated measurements of heterogeneous ice nuclei—suggesting maritime cumuli; and 3) based on nucleus seeding practice when the goal is to stimulate the growth of cumulus clouds. General ...

Virtual address translator

Abstract: A virtual address translator comprises a content addressed memory and a word addressed memory. A task name and subsegment number from a virtual address supplied by a processor are employed as a key word to search a content addressed memory and read out a subsegment descriptor if the key word is matched. The subsegment descriptor includes an absolute base address which is added to a deflection field to obtain an absolute memory address. The memory address is applied to a memory to permit transfer of a word between the processor and the memory. The processor may present any one of several task names depending upon whether the memory reference is made for an instruction or data for the processor, or for an instruction or data for an I/O connected to the processor. Bounds, residency and access privileges are checked using the subsegment descriptor. If a search of the content addressed memory reveals that the desired subsegment descriptor is not in the word addressed memory, the translator obtains the descriptor from memory and then generates the desired absolute memory address. The translator is provided with circuits generating values which indicate the efficiency of its operation. Controls are provided for selecting any one of several widths for the subsegment and deflection fields of virtual addresses received from the processor.

Remote controlled test interface unit

Abstract: A universal remotely controlled test interface test unit is adapted to be connected through plug connections to an on-site computing system having one or more central processing units and associated peripheral equipment. The test interface unit is provided with a limited function keyboard control for initiating tests and a transceiver for communicating with a data processing unit at a remote location which supplies format and control signals for use by the test interface unit and data signals to be communicated to the on-site computing system. The data signals received by the test interface unit are first entered into a buffer register to provide parallel outputs. The format control signals activate logic gating signals to cause the data signals in the buffer register to be arranged in a control register in a format which is compatible with the equipment to be tested. The control register is arranged to operate any part of the central processing system under test and any of its intended modes of operation and to initiate readout of information from any part of the computing system through the transceiver for processing and examination by the remotely located data processing unit.

Shared direct memory access controller

Abstract: A microprocessor system includes a microprocessor, a memory, and one or more direct memory access controllers, all connected to a common system bus which includes a system address bus and a system data bus. At least one of the direct memory access controllers is shared by a plurality of subsystem device controllers which may control peripheral devices having diverse characteristics. The microprocessor is limited in its instruction repertoire and may control peripheral devices only by means of an input and an output instruction. The shared direct memory access controller includes no circuitry which is specifically for controlling only a single type of peripheral device, the device dependent logic being located in subsystem device controllers. Data transfers may take place directly between the memory and, through the shared direct memory access controller, any selected one of the peripheral devices. In order to set up the actual data transfer, the microprocessor executes an Input instruction which addresses the status register in a selected subsystem device controller and returns this status to the microprocessor. Next, two Output instructions are executed to load a memory starting address into an address pointer counter in the shared direct memory access controller. Finally, an Output instruction is executed to address a control register in the selected subsystem device controller to load it with a command. After this last operation the actual data transfer takes place on a byte basis through the shared direct memory access controller between the memory and the selected subsystem device controller. The shared direct memory access controller includes an interrupt priority encoder and circuits responsive to an interrupt that is granted priority for placing the status and address of the interrupting subsystem device controller on the system bus. Circuits are included in the shared direct memory access controller for "handshaking" between it and the memory, and between it and the subsystem device controllers.

Noncooperative General Exchange

Abstract: Publisher Summary This chapter describes a new method of making a game out of general equilibrium. It is based on the noncooperative side of game theory, in the spirit of Nash and Cournot. The traders do not collude, but they do influence prices through their buy and sell orders. The noncooperative equilibria (NE) of the game are conceptually not too far removed from the classical competitive equilibria, the relationship between the two being especially close when there are many traders of each type and hence relatively stable prices. But when there are thin markets, substantial Pareto inefficiency in the NE, with trading sharply reduced in volume or otherwise displaced from the competitive pattern, is typically found. The chapter presents a sampling from a class of related models, suitable both for general-purpose microeconomic theory and for studying the phenomena of money and financial institutions.

Crop residue deflector means

Abstract: A deflector panel is pivotally mounted within the straw hood of a combine and is disposable between a first position wherein residue material emanating from the combine is deflected into a straw chopper and a second position wherein the emanating material is deflected through the residue outlet of the straw hood, forwardly of the straw chopper, and discharged onto the ground.

Some Variations of Lee's Algorithm

Abstract: Lee's algorithm is a pathfinding algorithm, which is often used in computer-aided design systems to route wires on printed circuit boards. This paper discusses some variations of Lee's algorithm which can be used in certain contexts to improve its efficiency. First, it is shown that, by storing frontier cells in an array of stacks rather than a single list, costly searching operations can be eliminated without significantly increasing storage requirements. Second, it is shown that if each path's cost is the sum of the weights of its cells then retrace codes can be assigned to cells as soon as they are reached rather than when they are expanded. Third, it is shown that if the additional restriction is made that each cell's weight is not a function of the state of any nonneighbor cell, then an encoding scheme requiring only two bits/cell can be used for both rectangular and hexagonal grids.

Spout control apparatus for agricultural machines

Abstract: The crop discharge spout of an agricultural machine is continuously adjusted so that the crop material discharged therefrom is always directed into a wagon connected to the rear of the agricultural machine. A sensor disposed on the agricultural machine cooperates with a mechanical follower which is coupled therefrom to the wagon to provide a signal indicative of the angle between the agricultural machine and the wagon. The signal is compared with a signal from a second sensor indicative of the angle of the direction of the crop discharge from the spout with respect to the agricultural machine and an error signal is developed from the difference therebetween. The error signal is coupled to a motor which rotates the discharge spout accordingly until the error signal is reduced to zero.

Reconfigurable data bus

Abstract: A digital data communication system having a plurality of digital nodal communication devices interconnected by a digital data bus in a fixed physical manner in which the data bus structure may be electrically reconfigured without physical modification of the digital data bus. The ability to reconfigure the digital data bus is accomplished by the insertion of a digital reconfigurable data bus module into the position on the digital data bus previously held by one of the digital nodal communication devices and the connection of the replaced digital nodal communication device to the digital reconfigurable data bus module. The digital reconfigurable data bus module contains a transceiver mechanism capable of receiving and transmitting digital information to and from the digital data bus, an adapter mechanism for communicating with the replaced digital nodal communication device and a switching mechanism capable of the multiple switching of data from the adapter section which is connected to the replaced digital nodal communication device to the transceiver section which is connected to the digital data bus. The digital reconfigurable data bus module allows a fixed configuration of nodal devices and connecting devices to provide the function of tree structured buses, ring structured buses, dedicated channels or combinations of any of them. The module facilitates the receipt, switching and retransmission of data on any selected bus pattern.

Modeling the ice-age climate

Abstract: The last great (Wisconsin) ice age has long held the interest of climatologists, geologists, and geographers as the best documented of the several ice ages of the last million years. Although local glaciation maximums varied by several thousand years, the time 18,000 B.P. (years before present) is globally representative of this event. The changes of flora and fauna that accompanied this ice age are recorded in an extensive paleoclimatic literature, and are supplemented by widespread evidence of changes in the physical character of the earth's surface, such as changes in sea level, sea-ice extent, and local orography. From these and other evidence, estimates of the local nature of the ice-age climate itself have been derived at selected sites in terms of such variables as the local wind, temperature, or rainfall. Although they are insufficient to portray the overall global climatic regime, these estimates indicate that the ice-age climate was substantially different from today's in many regions of the world.

A Generalized Bulk Model of the Oceanic Mixed Layer

Abstract: An initial-value problem for both the shallowing and deepening of the upper mixed layer of the ocean is presented, including storage and background dissipation of the turbulent kinetic energy produced by wind and released by convection. The numerical integration using Ocean Station Papa data suggests that periods of mixed-layer shallowing do not require a disjoined algorithm such as proposed by Kraus and Turner. Some characteristic modes of deepening, for example, the Kraus-Turner deepening, the Gill-Turner deepening and the Warren deepening, are identified as subsets of the present model.

Bi-directional scanner assembly

Abstract: An optical code reader employs a flying spot scanner which traces a plurality of forward scan patterns wherein each is off-set from one another, and a plurality of reverse scans wherein each is off-set from one another and the generation of each forward scan is followed by the generation of a reverse scan. Furthermore, the forward and reverse scans are randomly positioned with respect to one another and other reverse and forward scans.

Distributive tee coupler

Abstract: An optical coupling apparatus having first and second optical waveguides wherein optical signals are coupled therebetween in a distributive manner. The distributive coupling provides essentially equally distributed optical signals in the secondary guide while maintaining an essentially continuous flow of light in the primary guide.

Apparatus for processing interrupts in microprocessing systems

Abstract: Circuitry external of a microprocessor determines priority between different peripheral devices requesting interrupts to generate a restart vector and a signal granting priority to one of the interrupt-requesting devices. The peripheral device loads its status and address into two addressable registers connected to a common system bus. The restart vector is loaded into the instruction register of the microprocessor. The microprocessor treats the restart vector as an instruction to store the contents of the program counter in memory and loads certain bits of the restart vector into the program counter. These bits represent the starting address of a subroutine of eight instructions for analyzing the interrupt. An interrupt is recognized and the status and identification of the interrupting device is stored in a single instruction cycle. On the next instruction cycle the first instruction of the interrupt analysis routine may begin. During this analysis routine the contents of the two addressable registers may be read out to determine which device caused the interrupt and what action should be taken in view of the status of the interrupting device. Provision is made for processing interrupts other than those requested by peripheral devices, and each type of interrupt generates a different restart vector thus selecting a different address as the first instruction address of the interrupt analysis routine.

Skin treatment appliance

Abstract: A hand-held portable electrical skin treatment appliance and particularly for use in the care of facial skin wherein the appliance is provided with means for detachably mounting various skin treatment devices to a rotary drive output. The attachment device is provided with self-contained motion translating means for converting the rotary drive output orbital movement of the skin treatment device to enhance the massaging or cleansing effects to the skin of the user.

A Simple Approximation to the Average Queue Size in the Time-Dependent M/M/1 Queue

Abstract: The time-dependent equations for the M/M/1 queue can be reduced to a single equation for the expected queue size, but the equation is dependent on P0(t), the probability of no jobs in the system An exact equation for the behavior of P0(t) under special conditions is derived and an approximation relating P0(t) to Q(t), the expected queue size at time t, is derived for the case when the change in queue size is slow compared to the service rate It is found that the approximation affords a significant improvement over the use of a steady state approximation to the time-dependent queue and is simpler to use than the exact equations

PAS-II: An Interactive Task-Free Version of an Automatic Protocol Analysis System

Abstract: PAS-II, a computer program which represents a generalized version of an automatic protocol system (PAS-I) is described. PAS-II is a task-free, interactive, modular data analysis sis system for inferring the information processes used by a human from his verbal behavior while solving a problem. The output of the program is a problem behavior graph: a description of the subject's changing knowledge state during problem solving. As an example of system operation the PAS-II analysis of a short cryptarithmetic protocol is presented.

Perturbation Solution for the Flat Spin Recovery of a Dual-§pin Spacecraft

Abstract: Euler's differential equations for free-body attitude motion are solved for the constant bearing axis torque recovery maneuver of a spacecraft with a symmetric rotor and asymmetric platform. The rotor bearing axis coincides with the spacecraft's centroidal principal axis of least inertia. The recovery time and the residual nutation angle are algebraically related to the initial flat spin rate, the spacecraft inertia properties, and the bearing axis torque. The differential equations are solved by use of two asymptotic parameter expansions of the multiple time scale type, which are matched to a transition expansion with a limit process matching procedure.

Optional virtual memory system

Abstract: The present invention relates to a memory addressing mechanism which has been formulated to accommodate three address structures: real, based and virtual. To accomplish this result the address generation function in the memory addressing mechanism has been separated into two distinct parts, address computation and address translation. By merely changing the hardware components in the address translation part of the memory addressing mechanism and leaving the hardware in the address computation part constant, an optional memory addressing mechanism which supports either a real address structure, a based address structure or a virtual address structure can be implemented. Further, the present invention with the virtual address translation apparatus in cooperation with the fixed address computation apparatus provides a virtual addressing mechanism which will compute and retrieve a memory word utilizing a four-segment memory address with only two memory references.

Clock synchronization system

Abstract: In a fail soft synchronization clock system having a plurality of central processing units and a plurality of input-output units operably connected to one or more remotely located volatile cache memories there is provided a free-running, non-synchronized clock in each central processing unit. The clock outputs are connected to sets of synchronizing clock system logic circuits, one for each central processing unit, which disable the clocks of all other central processing units and selects their own associated clock as the input for producing a plurality of synchronized outputs employed in turn to time the operation of the processing system which is operably connected to the cache memories.

Dual channel signal detector circuit

Abstract: A dual channel signal detector circuit comprising an equalizer for responding to a variable peak amplitude input signal, in which the peaks are representative of data, so as to provide a substantially constant peak amplitude output signal having discrete data representative pulses spaced along a base line, which is substantially flat at the zero level in regions intermediate the pulses, for application to separate peak detection and amplitude detection channels. The peak detection channel produces data pulses each indicative of the relative time occurrence of the peak of a respective data representative pulse while the amplitude detection channel is triggered by signal levels of the data representative pulses exceeding a predetermined threshold to produce gating pulses for gating the data pulses to the circuit output substantially exclusive of any noise that may be present at the input of the circuit.

Method for non-destructive removal of semiconductor devices

Abstract: Semiconductor devices having a conductive lead pattern on the bottom of the device are bonded to conductive pads on a substrate to form an electrical connection therewith. The connection comprises two layers of conductive adhesive plastic separated by a small chip of conductive alloy which melts above the curing temperature of the adhesive plastic. The non-destructive removal of a semiconductor device from the substrate is accomplished by heating only the semiconductor device to be removed until the alloy chip under the device melts, thus, permitting the non-destructive removal of the semiconductor device without the application of force which would tend to destroy the semiconductor device.

Object identification system using an RF roll-call technique

Abstract: An object identification system using an RF roll-call technique wherein an interrogator illuminates a multitude of cooperating objects with a sequence of codes and receives from each such cooperating object an acknowledge signal immediately following the transmission of the code associated with that object and which terminates prior to completion of transmission of the next code in the sequence.