Showing papers by "Mitre Corporation published in 1980"
TL;DR: It was concluded that for moderate increases in nutrient concentrations, benthic productivity will be most enhanced in those sediments with very low concentrations of fine sized particles.
121 citations
TL;DR: Currently MITRE is developing a variety of TDM techniques for use on coaxial cable, the design of public key crypto systems for application to local networks, integrated data and voice systems, the technical control of local networks and local network protocols.
23 citations
TL;DR: Today's Air Force tactical communications requirements and capabilities are described, and some important technological opportunities are identified that hold promise for overcoming some of the projected problem areas in the 1990's.
Abstract: During the 1980's, many improvements will be made in the Air Force's ability to communicate in a battlefield environment. Programs like JTIDS, SEEK TALK, TRI-TAC, and the Ground Mobile Forces satellite communications terminals will improve the security, jam resistance, connectivity, and capacity of today's Air Force tactical communications. Even after these programs have been implemented, however, some important problem areas will remain, especially in our ability to resist a determined enemy's electronic warfare and physical attacks. This paper first describes today's Air Force tactical communications requirements and capabilities, and then summarizes the current problem areas. Currently planned programs to solve these problems are described for aircraft voice, aircraft data, ground-to-ground interconnections, and sensor/weapon data links. The problem areas that will remain after the implementation of these programs are then discussed. Some important technological opportunities are identified that hold promise for overcoming some of the projected problem areas in the 1990's. In addition, some system approaches are suggested for exploiting these technological opportunities, and for improving our use of older technologies. These system approaches emphasize reduced-information-rate operation, adaptive network techniques, network management/control, packet switching, and joint-Service, interoperable, common-user systems.
21 citations
TL;DR: Results relating to the expected properties of polytopes indicate that n-polytopes defined by “large” numbers of constraints are difficult to obtain by random processes, and the expected value of the number of vertices of polytope is considerably less than Klee's least upper bound.
Abstract: This paper provides answers to several questions raised by V. Klee regarding the efficacy of Mattheiss' algorithm for finding all vertices of convex polytopes. Several results relating to the expected properties of polytopes are given which indicate thatn-polytopes defined by “large” numbers of constraints are difficult to obtain by random processes, the expected value of the number of vertices of polytope is considerably less than Klee's least upper bound the expected performance of Mattheiss' algorithm is far better than Klee's upper bound would suggest.
21 citations
Proceedings Article•
18 Aug 1980TL;DR: The representations and algorithms of an implemented software solution are presented and the requirements that interactive frame instantiation imposes on constraint verification are discussed.
Abstract: This paper discusses the requirements that interactive frame instantiation imposes on constraint verification. The representations and algorithms of an implemented software solution are presented.
15 citations
TL;DR: The results of the MSA implementation of a (2, 1)15 code suggest that the MPA is a practical choice for codes having longer constraint lengths than are normally used with Viterbi decoding, and may serve as guidelines for future implementation ofThe MSA algorithm on faster, more capable microprocessors.
Abstract: A sequential algorithm for decoding convolutional codes, the multiple stack algorithm or MSA devised by Chevillat and Costello, has been implemented and tested on a Zilog Z-80 microcomputer system. The results of this implementation, when compared to those of a (2, 1)8 Viterbi algorithm implemented on the same microcomputer system, show that the MSA obtains significantly higher data throughput. The results of the MSA implementation of a (2, 1)15 code suggest that the MSA is a practical choice for codes having longer constraint lengths than are normally used with Viterbi decoding. The comparative results may serve as guidelines for future implementation of the MSA algorithm on faster, more capable microprocessors.
13 citations
TL;DR: The rationale and a preliminary design concept are presented for a new mobile ground-to-ground communications system to support tactical command and control because a single equipment supports multiple links while providing the benefits of high antenna gain and directivity.
Abstract: The rationale and a preliminary design concept are presented for a new mobile ground-to-ground communications system to support tactical command and control. Survivability is attained through high connectivity, antenna directivity, and spread-spectrum signals. Each node of the proposed network is equipped with a circular cylindrical array antenna capable of steering a narrow beam in the direction of one of its several neighbors. A single transceiver operates half-duplex m a flexible time-division format among the multiple links at a node. Each link uses a unique pseudonoise code, and the network as a whole employs code-division multiple access. Mobility and survivability are enhanced because a single equipment supports multiple links while providing the benefits of high antenna gain and directivity. Network entry and synchronization schemes are considered. System parameters are defined and link power budgets for signal-to-jammer and signal-to-noise ratios are calculated. Implementation prospects are addressed drawing on technology developments in antenna arrays, surface-acoustic wave signal processing, and adaptive routing in packet networks.
12 citations
TL;DR: It is shown in this paper that the performance of certain Rayleigh fast-fading channels can be accurately and efficiently evaluated using the elementary trapezoidal integration rule.
Abstract: It is shown in this paper that the performance of certain Rayleigh fast-fading channels can be accurately and efficiently evaluated using the elementary trapezoidal integration rule. The effects of intersymbol interference on such channels are analyzed.
10 citations
TL;DR: The use of communications relays is examined as a means of improving the operation of line-sight-links in an interference or jamming environment and the results obtained can be used to evaluate tradeoffs among the different options for reducing vulnerability to external interference.
Abstract: The use of communications relays is examined as a means of improving the operation of line-sight-links in an interference or jamming environment. Expressions are derived that define optimum relay locations and the number of relays. These relationships are functions of the system and interference parameters, as well as of the link and interference source geometry. Bounds on flight path orbits of airborne relays are also defined. Backlink operation with and without relays is considered, and the condition for identical relay locations for both forward link and backlink data flow is derived. The results obtained can be used to evaluate tradeoffs among the different options for reducing vulnerability to external interference.
10 citations
TL;DR: An algorithm for adaptive retransmission in a slottedALOHA communication channel has been designed and implemented and was found to provide better response time than a binary exponential backoff algorithm by simulation.
Abstract: An algorithm for adaptive retransmission in a slottedALOHA communication channel has been designed and implemented. This algorithm maintains the stability of the slotted-ALOHA channel under a wide variety of conditions and provides improvements in the response time of the channel. Simulation was used to test the algorithm for steady-state and impulse response. The algorithm was compared to a binary exponential backoff algorithm by simulation and was found to provide better response time.
9 citations
TL;DR: In this paper, the authors introduced the use of conjugate transforms in the study of τT semigroups of probability distribution functions and established their basic algebraic properties, including cancellation law, infinitely divisible elements, and solutions of equations in τT semiigroups.
TL;DR: This paper describes a system employing sophisticated satellites with steerable high gain, multibeam phased array antennas, which serve small low-cost user terminals, which achieves user access/distress without requiring dedicated access/emergency channels.
Abstract: This paper describes a system employing sophisticated satellites with steerable high gain, multibeam phased array antennas, which serve small low-cost user terminals. Adaptive techniques are used to form, point, and shape the beams. Pseudonoise signaling achieves user access/distress without requiring dedicated access/emergency channels. The L-band array has 32 elements, 34-dB gain; the user terminal has 15W transmitter, 3-dB gain antenna. The pseudonoise code and message structures are described. Approximately 100 users can be simultaneously acquired with success-probability exceeding 99%; system capacity can be increased by providing additional beams. System implementation is feasible in the Shuttle era.
TL;DR: An instrument has been developed that directly measures the multispectral absorption coefficient of turbid natural water using Monte Carlo techniques, and when used in conjunction with a spectrally matched total attenuation instrument, theSpectrally dependent scattering coefficient can also be derived.
Abstract: An instrument has been developed that directly measures the multispectral absorption coefficient of turbid natural water. The design incorporates methods for compensation of variation in the internal light source intensity, correction of the spectrally dependent nature of the optical elements, and correction for variation in background light level. When used in conjunction with a spectrally matched total attenuation instrument, the spectrally dependent scattering coefficient can also be derived. Systematic errors associated with multiple scattering have been estimated using Monte Carlo techniques.
Proceedings Article•
01 Jan 1980TL;DR: Ion implantation and thermal annealing techniques for processing junctions and back surface layers in solar cells are discussed in this article, where it is shown that implantation costs can be reduced to approximately 1 cent/watt.
Abstract: Ion implantation and thermal annealing techniques for processing junctions and back surface layers in solar cells are discussed. Standard 10 keV (31)p(+) junction implants and 25 keV (11)B(+) back surface implants in combination with three-step furnace annealing are used for processing a range of silicon materials and device structures. Cells with efficiencies up to 16.5% AM1 are being produced, and large-area terrestrial cells with implanted junctions and back fields being fabricated in pilot production exhibit average efficiencies in excess of 15% AM1. Thermal annealing methods for removal of the radiation damage caused by implantation should be replaced by transient processing techniques in future production. Design studies have been completed for solar cell processing implanters to support 10 MW/yr and 100 MW/yr production lines, and analyses indicate that implantation costs can be reduced to approximately 1 cent/watt.
14 Apr 1980
TL;DR: A formal model of multilevel security systems is presented, and a concept of expression flows is introduced, which allows us to use various techniques to certify systems that cannot be certified using current flow analysis techniques.
Abstract: A formal model of multilevel security systems is presented. We examine weaknesses of current security flow analysis mechanisms. A concept of expression flows is introduced, which allows us to use various techniques to certify systems that cannot be certified using current flow analysis techniques. We provide a method for generating static authorization requirements for systems in which authorization functions are only partially specified. We also attack the problem of using dynamic authorization functions for system certification.
TL;DR: The purpose of this note is to show how an apparently naive security analysis showing how information flow only to the array reference in the statement yields correct conclusions is shown, and how this approach may yield overestimates.
Abstract: Information flow security analysis is a technique that can be applied during th e design phase of a program or operating system to detect potential channels fo r compromising information. It can be applied to the programs themselves [1] or t o formal specifications [2]. It is known [1] that a statement that modifies an arra y reference indexed with a variable causes information flow to the whole array. Th e purpose of this note is to show how an apparently naive security analysis showin g flow only to the array reference in the statement yields correct conclusions. The simplest case where this situation comes up is the statement A(B) := O. B y any one of a number of definitions of information flow (see, for example, [3]), an y array element A(i) depends on, or may receive information from, the variable B. W e are assuming that any legal index for A is a possible value of B. This flow can b e seen intuitively by noting that if A(i) 0 after the statement is executed, one ca n deduce that B i. Thus, the correct information flow analysis of the statement A(B) := 0 is : B-> A(i) (all i). We use the arrow (->) to indicate possible flow ; in general , it is not possible to be precise about what information channels actually exist , and this approach may yield overestimates. However, the analysis B-> A(B) would be incomplete. An information flow security analysis policy assigns security levels to variables . Security levels are typically chosen from a lattice, whose partial orderin g indicates permissible information flows as follows. If we denote the security leve l of X by X, then information flow X-> Y is permitted only when X < Y. The curious fact is that if the statement A(B) := 0 can be shown to satisfy th e security policy using the naive analysis B-> A(B), then it is really secure wit h respect to the full analysis. This is true even when different elements of the arra y are assigned different security levels. For an informal demonstration, suppose we can prove tha t B < A(B) (*) when the statement A(B) := 0 is executed. This additional knowledge changes th e information flow analysis. The flow B-> A(i) occurs only for i such that B < A(i). The reason is that, for values …
14 Apr 1980
TL;DR: A methodology for demonstrating the security of trusted applications on a security kernel base is presented and consists of selecting and authenticating security criteria, and demonstrating through verification techniques that the implementation obeys the selected criteria.
Abstract: A methodology for demonstrating the security of trusted applications on a security kernel base is presented. The methodology consists of selecting and authenticating security criteria, and demonstrating through verification techniques that the implementation obeys the selected criteria. Difficulties encountered in the placement of a trusted application on top of a security kernel base motivated the development of the methodology.
TL;DR: In this article, ice nuclei measurements were made aboard a cloud-base aircraft during the 1975 Florida Area Cumulus Experiment (FACE) by using two techniques: the NCAR membrane development chamber and the acoustical counter.
Abstract: Ice nuclei measurements were made aboard a cloud-base aircraft during the 1975 Florida Area Cumulus Experiment. Two techniques were used to obtain the ice nuclei concentrations; membranes were collected and analyzed using the NCAR membrane development chamber and continuous ice nuclei concentrations were obtained using the NCAR acoustical counter. Results showed that the membrane technique failed to effectively detect ice nuclei in this maritime tropical area. However, the concentrations recorded by the acoustical counter showed natural afternoon diurnal increases which may have ramifications on cloud development and seeding potential within the particular study area.
TL;DR: The study concludes that there are no significant differences between the MRL's and non-MRL's with respect to innovation, interdisciplinarity, utilization of specialized equipment, concentration of funding, rate of tumover, duration of research areas, and level of effort per research paper.
Abstract: The performance of the 20 materials research laboratories (MRL's) at universities funded with institutional grants by the National Science Foundation, Department of Energy, and National Aeronautics and Space Administration is evaluated in comparison with 15 other universities (non-MRL's) receiving individually funded projects for materials research. Performance is measured by peer review and citation frequency analysis of publications, subjective evaluation of research achievements and researcher reputation by a panel of experts, review of equipment purchases and utilization, and analysis of administrative costs. The study concludes that there are no significant differences between the MRL's and non-MRL's with respect to innovation, interdisciplinarity, utilization of specialized equipment, concentration of funding, rate of tumover, duration of research areas, and level of effort per research paper. The MRL's have a greater number of major achievements and attract researchers with higher reputations. The MRL's tend to emphasize experimental work, and in about 70 percent of the materials research areas sponsored by the National Science Foundation there is no overlap between the two groups. Institutional grants involve much less total (federal plus university) administrative cost per grant dollar than project grants.
TL;DR: In this paper, the authors evaluated a single-sided linear induction motor (SLIM) as an integrated suspension/propulsion system (ISPS) for guided ground transportation vehicles.
Abstract: A summary of an experimental research project to evaluate a single-sided linear induction motor (SLIM) as an integrated suspension/ propulsion system (ISPS) for guided ground transportation vehicles is presented. Experimental results for rotating wheel tests of a full size section of a SLIM are presented. Emphasis is given to an application in the speed range of 200 to 500 km/h, however an extension of the results to lower speeds can be realized with further study of the data acquired. The results indicate that feasibility in such an application is limited to the extent that the adjudged benefits of ISPS outweigh the cost of the required onboard power conditioning unit (PCU). The size of the PCU increases with speed, nominal airgap, and the guidance/lift ratio desired. Results are presented to define the maximum practical speed for application as a function of the state of the art of PCU technology.
01 Oct 1980
TL;DR: A requirements matrix is proposed to categorize the functional capabilities required for characteristic user tasks and design guidelines can be tailored to required capabilities.
Abstract: The man-machine interface (MMI) is a critical element in the specification of computer software for on-line information systems. To help ensure effective MMI software design, a requirements matrix is proposed to categorize the functional capabilities required for characteristic user tasks. Based on this matrix, design guidelines can be tailored to required capabilities. This approach to specifying MMI design must be tried in system acquisition programs to evaluate its usefulness.
TL;DR: In this article, the authors deal with theoretical and empirical analysis of the economics of technological change (TC) in coal mines for the period 1951-1975, and divide the coal mines into underground and surface mines.
TL;DR: This paper traces the evolution of NATO communications from existing multiple, predominantly manual, dedicated networks to modern, common-user, automated, switched voice, and message networks being implemented as part of the NICS Stage I program.
Abstract: In 1970, the Defense Ministers of the Alliance approved an ambitious program to develop a modern, NATO-wide commonuser communications system called the NATO Integrated Communications System (NICS) and created a NICS Management Agency, NICSMA, with the responsibility of planning, engineering, and implementing the system The aim of the NICS is to provide rapid, secure, survivable, flexible, and reliable communications to all eligible political and military authorities in the exercise of command and control across the conflict spectrum This paper traces the evolution of NATO communications from existing multiple, predominantly manual, dedicated networks to modern, common-user, automated, switched voice, and message networks being implemented as part of the NICS Stage I program Organizational arrangements and operational requirements imposed on the NICS in support of improved NATO command and control systems are briefly reviewed A broad overview of the programmed enhancements that comprise NICS Stage I and its interfaces with other national strategic and tactical systems is presented The basic principles underlying the future digital NICS Stage II architecture and a broad concept for an evolutionary transition from the predominantly analog Stage I to the digital architecture are also described Key issues affecting the transition and interoperability with national tactical and strategic systems are identified
TL;DR: The system concept is based on accurate time-synchronization among all participants and represents a radical departure from current IFF methods, however, it does retain the basic interrogateresponse approach.
Abstract: Identification of friend or foe (IFF) in the tactical theater is a complex technical and operational problem with extremely important implications to the nation's success in waging war. A practical, inexpensive IFF system which can reliably identify friends in a hostile ECM environment is desperately needed by the United States and NATO. This paper presents an IFF system concept which utilizes existing technologies and devices to create a new tactical IFF system that addresses the following electronic counter-counter-measure (ECCM) problems: 1) vulnerability to enemy antiradiation missiles, 2) vulnerability to jamming, 3) vulnerability to enemy spoofing and deception, and 4) vulnerability to enemy exploitation ("eavesdropping"). The system concept is based on accurate time-synchronization among all participants and represents a radical departure from current IFF methods. However, it does retain the basic interrogateresponse approach. It utilizes spread-spectrum, low-data-rate signaling which offers substantial resistance to enemy jamming and makes spoofing and deception extremely difficult. The spreadspectrum techniques include: frequency hopping, time jitter, and intrapulse Coding. This combination of techniques is used to maximize the antijam and convert capabilities of the system without putting undue burden on a single technology.
TL;DR: In this paper, the relative economics of several OTEC mission concepts are compared to those for products manufactured by potential OTEC systems, since the efficiency and relative economic performance of an OTEC system is site specific, a generalization is made regarding site characteristics.
Proceedings Article•
01 Jan 1980TL;DR: In this paper, high-dose phosphorus implantation is followed by furnace annealing and simultaneous oxide growth to form high-efficiency, shallow junctions; the effect of the thermally grown oxide is a reduction of surface recombination velocity; the oxide also acts as moderately efficient AR coating.
Abstract: Open-circuit voltages as high as 0.645 V (AM0-25 C) have been obtained by a new process developed for low-resistivity silicon. The method utilizes high-dose phosphorus implantation, followed by furnace annealing and simultaneous oxide growth to form high-efficiency, shallow junctions. The effect of the thermally grown oxide is a reduction of surface recombination velocity; the oxide also acts as a moderately efficient AR coating. Boron doped silicon with resistivities from 0.1 to 0.3 ohm-cm has been processed according to this sequence; results show highest open-circuit voltage is attained with 0.1-ohm-cm starting material. The effects of bandgap narrowing, caused by high doping concentrations in the junction, were also investigated by implanting phosphorus over a wide range of dose levels.
TL;DR: In this article, a methodology for comparing phased implementation plans for a new fixed guideway transit system in an urban area is presented, and the economic comparision of alternative plans includes total as well as relative inflation of principal cost components.
Abstract: A methodology for comparing phased implementation plans for a new fixed guideway transit system in an urban area is presented. Four assumptions are made: (1) the guideway system replaces existing or planned bus service, (2) superior service on the new system results in increased ridership when compared to buses; (3) presence of the guideway facility redirects outward urban growth resulting in additional ridership, and (4) conversely, the absence of any action on the new guideway facility reinforces a diffuse urban growth pattern that creates an irreversible loss of transit ridership. The economic comparision of alternative plans includes total as well as “relative” inflation of principal cost components. A key feature of the proposed methodology is including in the comparisons the costs of private automobile mileage that could have been replaced by transit. These costs are expressed as “fuel” and “all other” automobile costs; favorable transit system implementation schedules can then be identified as a fu...