Combinatorial communications - Search for cyclic Hadamard matrices
Search for cyclic Hadamard matrices from difference set - combinatorial communications
MATRIX↗
SEARCH · Engineering Papers
Results for “combinatorial”
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Combinatorial communications - Enumeration of a special class of permutations
Enumeration of special class class of permutations - generating function expression and asymtotic expansion for recurrence relation - combinatorial communications
COMMUNICATION SYSTEM↗
Combinatorial communications - The target lemma
Target lemma in combinatorial communications - proof of geometric property of multivariate Gaussian distribution
TELECOMMUNICATION↗
Combinatorial analysis of multi-terminal devices.
Identification, coding and enumeration of distinguishable subnetwork configurations employing combinatorial analysis
PROBABILITY DENSITY↗
Combinatorial techniques for fault identification in multiterminal networks.
Combinatorial techniques for fault identification in multiterminal networks, discussing algorithms for computer oriented procedures and computer program flow chart
Happ, W. W.↗
Combinatorial techniques for fault identification in multi-terminal networks.
Fault identification and diagnosis in multiterminal devices by combinatorial techniques for computer programming
Happ, W. W.↗
Combinatorial structures in planetary reconnaissance.
Mariner 1969 high rate telemetry system portions pertinent to combinatorial mathematicians, discussing coding and encoding
Posner, E. C.↗
Description of the GDC program for the graphic display of three-dimensional models prepared by the combinatorial geometry technique
Computer programming for graphic display of combinatorial geometry
Guber, W.↗
The fully indecomposable matrix and its associated bipartite graph - An investigation of combinatorial and structural properties
Combinatorial properties of classes of nonnegative matrices
Roberts, E. J.↗
The 3-D world modeling with updating capability based on combinatorial geometry
A 3-D world modeling technique using range data is discribed. Range data quantify the distances from the sensor focal plane to the object surface, i.e., the 3-D coordinates of discrete points on the object surface are known. The approach proposed herein for 3-D world modeling is based on the Combinatorial Geometry (CG) method which is widely used in Monte Carlo particle transport calculations. First, each measured point on the object surface is surrounded by a small sphere with a radius determined by the range to that point. Then, the 3-D shapes of the visible surfaces are obtained by taking the (Boolean) union of all the spheres. The result is an unambiguous representation of the object's boundary surfaces. The pre-learned partial knowledge of the environment can be also represented using the CG Method with a relatively small amount of data. Using the CG type of representation, distances in desired directions to boundary surfaces of various objects are efficiently calculated. This feature is particularly useful for continuously verifying the world model against the data provided by a range finder, and for integrating range data from successive locations of the robot during motion. The efficiency of the proposed approach is illustrated by simulations of a spherical robot in a 3-D room in the presence of moving obstacles and inadequate prelearned partial knowledge of the environment.
Goldstein, M.↗
Computational efficiency of parallel combinatorial OR-tree searches
The performance of parallel combinatorial OR-tree searches is analytically evaluated. This performance depends on the complexity of the problem to be solved, the error allowance function, the dominance relation, and the search strategies. The exact performance may be difficult to predict due to the nondeterminism and anomalies of parallelism. The authors derive the performance bounds of parallel OR-tree searches with respect to the best-first, depth-first, and breadth-first strategies, and verify these bounds by simulation. They show that a near-linear speedup can be achieved with respect to a large number of processors for parallel OR-tree searches. Using the bounds developed, the authors derive sufficient conditions for assuring that parallelism will not degrade performance and necessary conditions for allowing parallelism to have a speedup greater than the ratio of the numbers of processors. These bounds and conditions provide the theoretical foundation for determining the number of processors required to assure a near-linear speedup.
Li, Guo-Jie↗
Combinatorial FSK modulation for power-efficient high-rate communications
Deep-space and satellite communications systems must be capable of conveying high-rate data accurately with low transmitter power, often through dispersive channels. A class of noncoherent Combinatorial Frequency Shift Keying (CFSK) modulation schemes is investigated which address these needs. The bit error rate performance of this class of modulation formats is analyzed and compared to the more traditional modulation types. Candidate modulator, demodulator, and digital signal processing (DSP) hardware structures are examined in detail. System-level issues are also discussed.
Wagner, Paul K.↗
Combinatorial FSK modulation for power-efficient high-rate communications
Deep-space and satellite communications systems must be capable of conveying high-rate data accurately with low transmitter power, often through dispersive channels. A class of noncoherent Combinatorial Frequency Shift Keying (CFSK) modulation schemes is investigated which address these needs. The bit error rate performance of this class of modulation formats is analyzed and compared to the more traditional modulation types. Candidate modulator, demodulator, and digital signal processing (DSP) hardware structures are examined in detail. System-level issues are also discussed.
Wagner, Paul K.↗
Combinatorial pulse position modulation for power-efficient free-space laser communications
A new modulation technique called combinatorial pulse position modulation (CPPM) is presented as a power-efficient alternative to quaternary pulse position modulation (QPPM) for direct-detection, free-space laser communications. The special case of 16C4PPM is compared to QPPM in terms of data throughput and bit error rate (BER) performance for similar laser power and pulse duty cycle requirements. The increased throughput from CPPM enables the use of forward error corrective (FEC) encoding for a net decrease in the amount of laser power required for a given data throughput compared to uncoded QPPM. A specific, practical case of coded CPPM is shown to reduce the amount of power required to transmit and receive a given data sequence by at least 4.7 dB. Hardware techniques for maximum likelihood detection and symbol timing recovery are presented.
Budinger, James M.↗
Thermal analysis of combinatorial solid geometry models using SINDA
Algorithms have been developed using Monte Carlo techniques to determine the thermal network parameters necessary to perform a finite difference analysis on Combinatorial Solid Geometry (CSG) models. Orbital and laser fluxes as well as internal heat generation are modeled to facilitate satellite modeling. The results of the thermal calculations are used to model the infrared (IR) images of targets and assess target vulnerability. Sample analyses and validation are presented which demonstrate code products.
Gerencser, Diane↗
Aerospace applications on integer and combinatorial optimization
Research supported by NASA Langley Research Center includes many applications of aerospace design optimization and is conducted by teams of applied mathematicians and aerospace engineers. This paper investigates the benefits from this combined expertise in formulating and solving integer and combinatorial optimization problems. Applications range from the design of large space antennas to interior noise control. A typical problem. for example, seeks the optimal locations for vibration-damping devices on an orbiting platform and is expressed as a mixed/integer linear programming problem with more than 1500 design variables.
Padula, S. L.↗
Aerospace applications of integer and combinatorial optimization
Research supported by NASA Langley Research Center includes many applications of aerospace design optimization and is conducted by teams of applied mathematicians and aerospace engineers. This paper investigates the benefits from this combined expertise in solving combinatorial optimization problems. Applications range from the design of large space antennas to interior noise control. A typical problem, for example, seeks the optimal locations for vibration-damping devices on a large space structure and is expressed as a mixed/integer linear programming problem with more than 1500 design variables.
Padula, S. L.↗
Aerospace Applications of Integer and Combinatorial Optimization
Research supported by NASA Langley Research Center includes many applications of aerospace design optimization and is conducted by teams of applied mathematicians and aerospace engineers. This paper investigates the benefits from this combined expertise in formulating and solving integer and combinatorial optimization problems. Applications range from the design of large space antennas to interior noise control. A typical problem, for example, seeks the optimal locations for vibration-damping devices on an orbiting platform and is expressed as a mixed/integer linear programming problem with more than 1500 design variables.
Padula, S. L.↗