The 30/20 GHz fixed communications systems service demand assessment. Volume 2: Main report

A forecast of demand for telecommunications services through the year 2000 is presented with particular reference to demand for satellite communications. Estimates of demand are provided for voice, video, and data services and for various subcategories of these services. The results are converted to a common digital measure in terms of terabits per year and aggregated to obtain total demand projections

Rebuilding the Habitable Zone from the Bottom Up with Computational Zones

Computation, if treated as a set of physical processes that act on information represented by states of matter, encompasses biological systems, digital systems, and other constructs, and may be a fundamental measure of living systems. The opportunity for biological computation, represented in the propagation and selection-driven evolution of information-carrying organic molecular structures, has been partially characterized in terms of planetary habitable zones based on primary conditions such as temperature and the presence of liquid water. A generalization of this concept to computational zones is proposed, with constraints set by three principal characteristics: capacity, energy, and instantiation (or substrate). Computational zones naturally combine traditional habitability factors, including those associated with biological function that incorporate the chemical milieu, constraints on nutrients and free energy, as well as element availability. Two example applications are presented by examining the fundamental thermodynamic work efficiency and Landauer limit of photon-driven biological computation on planetary surfaces and of generalized computation in stellar energy capture structures (a.k.a. Dyson structures). It is shown that computational zones involving nested structures or substellar objects could manifest unique observational signatures as cool far-infrared emitters. While this is an entirely hypothetical example, its simplicity offers a useful, complementary introduction to computational zones.Comment: 31 pages, 3 figures, submitted to The Astrobiology Journa

USEFUL MEASURES OF COMPLEXITY: A MODEL OF ASSESSING DEGREE OF COMPLEXITY IN ENGINEERED SYSTEMS AND ENGINEERING PROJECTS

Many modern systems are very complex, a reality which can affect their safety and reliability of operations. Systems engineers need new ways to measure problem complexity. This research lays the groundwork for measuring the complexity of systems engineering (SE) projects. This research proposes a project complexity measurement model (PCMM) and associated methods to measure complexity. To develop the PCMM, we analyze four major types of complexity (structural complexity, temporal complexity, organizational complexity, and technological complexity) and define a set of complexity metrics. Through a survey of engineering projects, we also develop project profiles for three types of software projects typically used in the U.S. Navy to provide empirical evidence for the PCMM. The results of our work on these projects show that as a project increases in complexity, the more difficult and expensive it is for a project to meet all requirements and schedules because of changing interactions and dynamics among the project participants and stakeholders. The three projects reveal reduction of project complexity by setting a priority and a baseline in requirements and project scope, concentrating on the expected deliverable, strengthening familiarity of the systems engineering process, eliminating redundant processes, and clarifying organizational roles and decision-making processes to best serve the project teams while also streamlining on business processes and information systems.Civilian, Department of the NavyApproved for public release. Distribution is unlimited

Conceptual design and feasibility evaluation model of a 10 to the 8th power bit oligatomic mass memory. Volume 1: Conceptual design

The oligatomic (mirror) thin film memory technology is a suitable candidate for general purpose spaceborne applications in the post-1975 time frame. Capacities of around 10 to the 8th power bits can be reliably implemented with systems designed around a 335 million bit module. The recommended mode was determined following an investigation of implementation sizes ranging from an 8,000,000 to 100,000,000 bits per module. Cost, power, weight, volume, reliability, maintainability and speed were investigated. The memory includes random access, NDRO, SEC-DED, nonvolatility, and dual interface characteristics. The applications most suitable for the technology are those involving a large capacity with high speed (no latency), nonvolatility, and random accessing

A New Multi-Viewpoint and Multi-Level Clustering Paradigm for Efficient Data Mining Tasks

International audienc

A Generalized Knowledge Production Function

This paper presents a generalized production model based on the knowledge production function. The model allows the relationships between corporate competitiveness strategy, innovation, efficiency, productivity growth and outsourcing to be investigated at the firm level in a number of steps. First, in reviewing recent developments of researches on the above relationships, provide discussion on data and the methods of measuring these variables. Second, depending on availability of information, different measures are transferred into single multidimensional index of corporate strategy using principal component analysis. Third, stochastic frontier production function and factor productivity analysis are used to estimate the efficiency and factor productivity growth at the firm level. Fourth, the causal relationships between the five variables of interest are established and modelled. Finally, given the direction of causality, the implications of the findings for estimation of the relationship are discussed. For the empirical analysis we use Swedish firm-level innovation survey data covering both manufacturing and service sectors.Competition; innovation; outsourcing; productivity; efficiency; causality; firm

Efficient Modeling of an Array Antenna and Requirements for Maritime Mobile Reception of Meteorological Satellite Imagery

Wireless communication is an integral part of safety at sea. Direct broadcasts from public weather satellites on L- and X-band provide real-time weather observations and weather product dissemination to end users. These high-bandwidth broadcasts offer enhanced data throughput and require accurate pointing of high-gain antennas. An electronically-steered array antenna can provide high gain and rapid beam steering without moving parts, suitable for deployment on small vessels offshore. Figures of merit, such as array antenna gain and input impedance, vary with the beam steering angle as a consequence of mutual coupling between array elements. The electromagnetic design of an electronically-steered array antenna is more complex than a parabolic dish or a fixed broadside array, requiring an iterative development process and a computationally efficient method of simulating the array. This work addresses the validation of an efficient method for array simulation, a necessary first step in the design process of a deployable array. Starting with a small L-band subarray, a Fourier windowing method is applied to approximate the scan-dependent behavior of an electronically-steered array from an efficient numerical model in a periodic unit cell. Results are validated against experimental measurements of hardware prototypes and explicit numerical models of the subarray. The iterative design of antenna elements in an array environment and construction of a full-size array are left for future work