12,978 research outputs found
Shape-based cost analysis of skeletal parallel programs
Institute for Computing Systems ArchitectureThis work presents an automatic cost-analysis system for an implicitly parallel skeletal
programming language.
Although deducing interesting dynamic characteristics of parallel programs (and in
particular, run time) is well known to be an intractable problem in the general case, it
can be alleviated by placing restrictions upon the programs which can be expressed.
By combining two research threads, the âskeletalâ and âshapelyâ paradigms which
take this route, we produce a completely automated, computation and communication
sensitive cost analysis system. This builds on earlier work in the area by quantifying
communication as well as computation costs, with the former being derived for the
Bulk Synchronous Parallel (BSP) model.
We present details of our shapely skeletal language and its BSP implementation strategy
together with an account of the analysis mechanism by which program behaviour
information (such as shape and cost) is statically deduced. This information can be
used at compile-time to optimise a BSP implementation and to analyse computation
and communication costs. The analysis has been implemented in Haskell. We consider
different algorithms expressed in our language for some example problems and
illustrate each BSP implementation, contrasting the analysis of their efficiency by traditional,
intuitive methods with that achieved by our cost calculator. The accuracy of
cost predictions by our cost calculator against the run time of real parallel programs is
tested experimentally.
Previous shape-based cost analysis required all elements of a vector (our nestable bulk
data structure) to have the same shape. We partially relax this strict requirement on data
structure regularity by introducing new shape expressions in our analysis framework.
We demonstrate that this allows us to achieve the first automated analysis of a complete
derivation, the well known maximum segment sum algorithm of Skillicorn and Cai
Relay: A New IR for Machine Learning Frameworks
Machine learning powers diverse services in industry including search,
translation, recommendation systems, and security. The scale and importance of
these models require that they be efficient, expressive, and portable across an
array of heterogeneous hardware devices. These constraints are often at odds;
in order to better accommodate them we propose a new high-level intermediate
representation (IR) called Relay. Relay is being designed as a
purely-functional, statically-typed language with the goal of balancing
efficient compilation, expressiveness, and portability. We discuss the goals of
Relay and highlight its important design constraints. Our prototype is part of
the open source NNVM compiler framework, which powers Amazon's deep learning
framework MxNet
Advanced Integrated Power and Attitude Control System (IPACS) study
Integrated Power and Attitude Control System (IPACS) studies performed over a decade ago established the feasibility of simultaneously satisfying the demands of energy storage and attitude control through the use of rotating flywheels. It was demonstrated that, for a wide spectrum of applications, such a system possessed many advantages over contemporary energy storage and attitude control approaches. More recent technology advances in composite material rotors, magnetic suspension systems, and power control electronics have triggered new optimism regarding the applicability and merits of this concept. This study is undertaken to define an advanced IPACS and to evaluate its merits for a space station application. System and component designs are developed to establish the performance of this concept and system trade studies conducted to examine the viability of this approach relative to conventional candidate systems. It is clearly demonstrated that an advanced IPACS concept is not only feasible, but also offers substantial savings in mass and life-cycle cost for the space station mission
Integrated orbital servicing study for low-cost payload programs. Volume 2: Technical and cost analysis
Orbital maintenance concepts were examined in an effort to determine a cost effective orbital maintenance system compatible with the space transportation system. An on-orbit servicer maintenance system is recommended as the most cost effective system. A pivoting arm on-orbit servicer was selected and a preliminary design was prepared. It is indicated that orbital maintenance does not have any significant impact on the space transportation system
The Copernicus project
The Copernicus spacecraft, to be launched on May 4, 2009, is designed for scientific exploration of the planet Pluto. The main objectives of this exploration is to accurately determine the mass, density, and composition of the two bodies in the Pluto-Charon system. A further goal of the exploration is to obtain precise images of the system. The spacecraft will be designed for three axis stability control. It will use the latest technological advances to optimize the performance, reliability, and cost of the spacecraft. Due to the long duration of the mission, nominally 12.6 years, the spacecraft will be powered by a long lasting radioactive power source. Although this type of power may have some environmental drawbacks, currently it is the only available source that is suitable for this mission. The planned trajectory provides flybys of Jupiter and Saturn. These flybys provide an opportunity for scientific study of these planets in addition to Pluto. The information obtained on these flybys will supplement the data obtained by the Voyager and Galileo missions. The topics covered include: (1) scientific instrumentation; (2) mission management, planning, and costing; (3) power and propulsion system; (4) structural subsystem; (5) command, control, and communication; and (6) attitude and articulation control
Aeronautical Engineering: A special bibliography with indexes, supplement 72, July 1976
This bibliography lists 184 reports, articles, and other documents introduced into the NASA scientific and technical information system in June 1976
Carbon Dioxide Observational Platform System (CO-OPS), feasibility study
The Carbon Dioxide Observational Platform System (CO-OPS) is a near-space, geostationary, multi-user, unmanned microwave powered monitoring platform system. This systems engineering feasibility study addressed identified existing requirements such as: carbon dioxide observational data requirements, communications requirements, and eye-in-the-sky requirements of other groups like the Defense Department, the Forestry Service, and the Coast Guard. In addition, potential applications in: earth system science, space system sciences, and test and verification (satellite sensors and data management techniques) were considered. The eleven month effort is summarized. Past work and methods of gathering the required observational data were assessed and rough-order-of magnitude cost estimates have shown the CO-OPS system to be most cost effective (less than $30 million within a 10 year lifetime). It was also concluded that there are no technical, schedule, or obstacles that would prevent achieving the objectives of the total 5-year CO-OPS program
The Marginal Cost of Public Funds is the Ratio of Mean Income to median Income
The marginal cost of public funds is the equilibrium price at the intersection of the appropriately-defined demand curve for and the supply curve of public expenditure. In a world with identical people and with no excess burden of taxation, that price would have to be 1. Otherwise the median voter's choice of a demogrant - or of its opposite, a head tax - fixes the marginal cost of public funds at the ratio of the mean income to the median income. A proof of this assertion is presented not for its realism, but because it calls attention to the interaction of the different influences upon the marginal cost of public funds.Marginal Cost of Public Funds
Impact of end effector technology on telemanipulation performance
Generic requirements for end effector design are briefly summarized as derived from generic functional and operational requirements. Included is a brief summary of terms and definitions related to end effector technology. The second part contains a brief overview of end effector technology work as JPL during the past ten years, with emphasis on the evolution of new mechanical, sensing and control capabilities of end effectors. The third and major part is devoted to the description of current end effector technology. The ongoing work addresses mechanical, sensing and control details with emphasis on mechanical ruggedness, increased resolution in sensing, and close electronic and control integration with overall telemanipulator control system
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