Analytical solutions to constrained hypersonic flight trajectories

The flight trajectory of aerospace vehicles subject to a class of path constraints is considered. The constrained dynamics is shown to be a natural two-time-scale system. Asymptotic analytical solutions are obtained. Problems of trajectory optimization and guidance can be dramatically simplified with these solutions. Applications in trajectory design for an aerospace plane strongly support the theoretical development

Trajectory optimization for the National Aerospace Plane

The primary objective of this research is to develop an efficient and robust trajectory optimization tool for the optimal ascent problem of the National Aerospace Plane (NASP). This report is organized in the following order to summarize the complete work: Section two states the formulation and models of the trajectory optimization problem. An inverse dynamics approach to the problem is introduced in Section three. Optimal trajectories corresponding to various conditions and performance parameters are presented in Section four. A midcourse nonlinear feedback controller is developed in Section five. Section six demonstrates the performance of the inverse dynamics approach and midcourse controller during disturbances. Section seven discusses rocket assisted ascent which may be beneficial when orbital altitude is high. Finally, Section eight recommends areas of future research

Misc. Pub. 85-4

Paper copies in Archives, Acc #:2013-0059Soils have been surveyed in various parts of Alaska to meet resource -development needs since territorial days. These surveys have been conducted and published by the National Cooperative Soil Survey since 1952 and are a joint effort of the United States Department of Agriculture Soil Conservation Service and the Alaska Agricultural Experiment Station. Initially, government agencies were the major users of such soil surveys because land ownership was controlled almost entirely by government agencies. However, the demand for soils and geographic information increased substantially as population increased and urban areas grew following the discovery of oil on the Kenai Peninsula during the 1950s and on the North Slope in the late 1960s. Interest also heightened when the state gained titles to a large portion of land following statehood in 1959. The National Cooperative Soil Survey (NCSS) published many soil surveys for areas of intensive land use or potential land development. These soil surveys often are underutilized or misused. This publication, "Soil Survey and Its Use in Alaska," was developed over three years based on my field reviews of NCSS activities in Alaska as well as on my discussions with users of soil surveys regarding questions and problems arising from using the reports. In this publication, soil surveys and their use in Alaska are reviewed and discussed.Preface -- Introduction: What is Soil? Early Works, Current Status, Table 1: Status of National Cooperative Soil Survey (NCSS) in Alaska (Dec. 1984), National Cooperative Soil Survey -- How Soil Surveys are Made -- How Soils are Classified and Named: Soil Classification, Map Units -- The Use of Soil Survey: Soil: A Valuable Resources, General Resource Planning, Regional Land-Use or Watershed Planning, Community Planning, Agricultural Development, Engineering Interpretation, Environmental Protection, Recreation and Wildlife Management, Other Potential Uses in Alaska -- Problems and Questions About Soil Surveys: Map Scale and Order of Survey, Map Unit Inclusion, Table 2: General guidelines for identifying intensity of soil surveys, Land Capability Classification, Misuse of Soil Surveys, Over-Interpretation of Soil Surveys, Automated Data-Processing in Soil Survey, Taxonomic Unit vx. Map Unit, Soil Survey Report Format, Soil Mapping on the Arctic Slope -- Future Challenges of NCSS in Alaska -- Conclusions -- Reference

Quasiparticles in the XXZ model

The coordinate Bethe ansatz solutions of the XXZ model for a one-dimensional spin-1/2 chain are analyzed with focus on the statistical properties of the constituent quasiparticles. Emphasis is given to the special cases known as XX, XXX, and Ising models, where considerable simplifications occur. The XXZ spectrum can be generated from separate pseudovacua as configurations of sets of quasiparticles with different exclusion statistics. These sets are complementary in the sense that the pseudovacuum of one set contains the maximum number of particles from the other set. The Bethe ansatz string solutions of the XXX model evolve differently in the planar and axial regimes. In the Ising limit they become ferromagnetic domains with integer-valued exclusion statistics. In the XX limit they brake apart into hard-core bosons with (effectively) fermionic statistics. Two sets of quasiparticles with spin 1/2 and fractional statistics are distinguished, where one set (spinons) generates the XXZ spectrum from the unique, critical ground state realized in the planar regime, and the other set (solitons) generates the same spectrum from the twofold, antiferromagnetically ordered ground state realized in the axial regime. In the Ising limit, the solitons become antiferromagnetic domain walls.Comment: 6 figure

Hierarchical Cooperation for Operator-Controlled Device-to-Device Communications: A Layered Coalitional Game Approach

Device-to-Device (D2D) communications, which allow direct communication among mobile devices, have been proposed as an enabler of local services in 3GPP LTE-Advanced (LTE-A) cellular networks. This work investigates a hierarchical LTE-A network framework consisting of multiple D2D operators at the upper layer and a group of devices at the lower layer. We propose a cooperative model that allows the operators to improve their utility in terms of revenue by sharing their devices, and the devices to improve their payoff in terms of end-to-end throughput by collaboratively performing multi-path routing. To help understanding the interaction among operators and devices, we present a game-theoretic framework to model the cooperation behavior, and further, we propose a layered coalitional game (LCG) to address the decision making problems among them. Specifically, the cooperation of operators is modeled as an overlapping coalition formation game (CFG) in a partition form, in which operators should form a stable coalitional structure. Moreover, the cooperation of devices is modeled as a coalitional graphical game (CGG), in which devices establish links among each other to form a stable network structure for multi-path routing.We adopt the extended recursive core, and Nash network, as the stability concept for the proposed CFG and CGG, respectively. Numerical results demonstrate that the proposed LCG yields notable gains compared to both the non-cooperative case and a LCG variant and achieves good convergence speed.Comment: IEEE Wireless Communications and Networking Conference 201