Note on arithmetic codes and arithmetic distance

Cyclic arithmetic codes and their distance properties with demonstration of modular arithmetic weight invariance to code word cyclic shift

Water Balance of a Small Lake in a Permafrost Region

The work upon which this report is based was supported in part by funds (Project A-031-ALAS) provided by the United States Department of the Interior, Office of Water Resources Research, as authorized under the Water Resources Act of 1964, as amended

Flexible high speed codec

The project's objective is to develop an advanced high speed coding technology that provides substantial coding gains with limited bandwidth expansion for several common modulation types. The resulting technique is applicable to several continuous and burst communication environments. Decoding provides a significant gain with hard decisions alone and can utilize soft decision information when available from the demodulator to increase the coding gain. The hard decision codec will be implemented using a single application specific integrated circuit (ASIC) chip. It will be capable of coding and decoding as well as some formatting and synchronization functions at data rates up to 300 megabits per second (Mb/s). Code rate is a function of the block length and can vary from 7/8 to 15/16. Length of coded bursts can be any multiple of 32 that is greater than or equal to 256 bits. Coding may be switched in or out on a burst by burst basis with no change in the throughput delay. Reliability information in the form of 3-bit (8-level) soft decisions, can be exploited using applique circuitry around the hard decision codec. This applique circuitry will be discrete logic in the present contract. However, ease of transition to LSI is one of the design guidelines. Discussed here is the selected coding technique. Its application to some communication systems is described. Performance with 4, 8, and 16-ary Phase Shift Keying (PSK) modulation is also presented

A Water Distribution System for Cold Regions: The Single Main Recirculation Method: An Historical Review, Field Evaluation, and Suggested Design Procedures

Students and residents of the Arctic are familiar with the many problems peculiar to the geographical area. This monograph will consider an adequate, safe, and reliable water distribution system. Water supply, together with housing, transportation, and waste disposal, are demanded when a remote area becomes established as a permanent settlement. As long as the population of the North was widely distributed in small mining camps, villages, and individual cabins, water distribution systems were not necessary, as shallow wells and nearby streams adequately served most needs. With the rapidly increasing settlement of the vast lands of the North, the population is being centered in communities rather than distributed over large areas. The world population explosion will undoubtedly contribute to increasing immigration into Arctic and sub-Arctic areas. These changes have already created a need for modern water distribution systems, a need which will become more critical with time.The research upon which this publication is based was performed in accordance with Contract No. ph 86-67-18 with the U.S. Public Health Service, Department of Health, Education, and Welfare. Lastly, the support of the Institute of Water Resources, University of Alaska is acknowledged, through an Office of Water Resources Research grant A-018-Alas

Wind tunnel tests of Space Shuttle external tank insulation material in the aerothermal tunnel at elevated (1440 deg F) total temperatures

Tests of the space shuttle external tank foam insulation were conducted in the von Karman Gas Dynamics Facility Tunnel C. For these tests, Tunnel C was run at Mach 4 with a total temperature of 1440 F and a total pressure which varied from 30-100 psia. Cold wall heating rates were changed by varying the test article support wedge angle and by adding and removing a shock generator or a cylindrical protuberance. Selected results are presented to illustrate the test techniques and typical data obtained

Electromagnetic energy transfer and switching in nanoparticle chain arrays below the diffraction limit

Electromagnetic energy transfer in plasmon wires consisting of chains of closely spaced metal nanoparticles can occur below the diffraction limit by means of coupled plasmon modes. Coherent propagation with group velocities that exceed 0.1 c is possible in straight wires and around sharp corners (bending radius much less than wavelength of visible light). Energy transmission through chain networks is possible at high efficiencies and is a strong function of the frequency and polarization direction of the plasmon mode. Although these structures exhibit transmission losses due to heating of about 3 dB/500 nm, they have optical functionality that cannot be obtained in other ways at a length scale ≪1 μm

A Plan of Farm Organization for Hill Land Farms in Southeastern Ohio

Exact date of bulletin unknown.PDF pages: 2

Reflection high-energy electron diffraction analysis of polycrystalline films with grain size and orientation distributions

We report a computationally efficient algorithm to calculate reflection high-energy electron diffraction (RHEED) intensities from well-textured, small-grained polycrystalline films in the kinematic limit. We also show how the intensity maps of the spots in a RHEED pattern from such a film can be quantitatively analyzed to determine the film's average grain size, as well as its in-plane orientation and texture distributions. We find that the in-plane orientation and texture distribution widths of these films can be determined to within 1 degree and that the average lateral grain size can be measured to within a fraction of a nanometer after suitable calibration of our technique