397 research outputs found
Design study of wind turbines 50 kW to 3000 kW for electric utility applications: Analysis and design
In the conceptual design task, several feasible wind generator systems (WGS) configurations were evaluated, and the concept offering the lowest energy cost potential and minimum technical risk for utility applications was selected. In the optimization task, the selected concept was optimized utilizing a parametric computer program prepared for this purpose. In the preliminary design task, the optimized selected concept was designed and analyzed in detail. The utility requirements evaluation task examined the economic, operational, and institutional factors affecting the WGS in a utility environment, and provided additional guidance for the preliminary design effort. Results of the conceptual design task indicated that a rotor operating at constant speed, driving an AC generator through a gear transmission is the most cost effective WGS configuration. The optimization task results led to the selection of a 500 kW rating for the low power WGS and a 1500 kW rating for the high power WGS
Physically Dense Server Architectures.
Distributed, in-memory key-value stores have emerged as one of today's most
important data center workloads. Being critical for the scalability of modern
web services, vast resources are dedicated to key-value stores in order
to ensure that quality of service guarantees are met. These resources include:
many server racks to store terabytes of key-value data, the power necessary to
run all of the machines, networking equipment and bandwidth, and the data center
warehouses used to house the racks.
There is, however, a mismatch between the key-value store software and the
commodity servers on which it is run, leading to inefficient use of resources.
The primary cause of inefficiency is the overhead incurred from processing
individual network packets, which typically carry small payloads, and require
minimal compute resources. Thus, one of the key challenges as we enter the
exascale era is how to best adjust to the paradigm shift from compute-centric
to storage-centric data centers.
This dissertation presents a hardware/software solution that addresses the
inefficiency issues present in the modern data centers on which key-value
stores are currently deployed. First, it proposes two physical server
designs, both of which use 3D-stacking technology and low-power CPUs to improve
density and efficiency. The first 3D architecture---Mercury---consists of stacks
of low-power CPUs with 3D-stacked DRAM. The second
architecture---Iridium---replaces DRAM with 3D NAND Flash to improve density.
The second portion of this dissertation proposes and enhanced version of the
Mercury server design---called KeyVault---that incorporates integrated,
zero-copy network interfaces along with an integrated switching fabric. In order
to utilize the integrated networking hardware, as well as reduce the
response time of requests, a custom networking protocol is proposed. Unlike
prior works on accelerating key-value stores---e.g., by completely bypassing the
CPU and OS when processing requests---this work only bypasses the CPU and OS
when placing network payloads into a process' memory. The insight behind this is
that because most of the overhead comes from processing packets in the OS
kernel---and not the request processing itself---direct placement of packet's
payload is sufficient to provide higher throughput and lower latency than prior
approaches.PhDComputer Science and EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/111414/1/atgutier_1.pd
Voyager spacecraft phase B, task D. Volume 11 - Engineering study task - Photo imaging system Final report
Systems engineering analysis of photoimaging systems for optimum photographic coverage of Mars during 1973 Voyager missio
Dispersed storage and generation case studies
Three installations utilizing separate dispersed storage and generation (DSG) technologies were investigated. Each of the systems is described in costs and control. Selected institutional and environmental issues are discussed, including life cycle costs. No unresolved technical, environmental, or institutional problems were encountered in the installations. The wind and solar photovoltaic DSG were installed for test purposes, and appear to be presently uneconomical. However, a number of factors are decreasing the cost of DSG relative to conventional alternatives, and an increased DSG penetration level may be expected in the future
Mod-1 wind turbine generator analysis and design report, volume 1
The activities leading to the completion of detail design of the MOD-1 wind turbine generator are described. Emphasis is placed on the description of the design as it finally evolved. However, the steps through which the design progressed are also traced in order to understand the major design decisions
Index to 1985 NASA Tech Briefs, volume 10, numbers 1-4
Short announcements of new technology derived from the R&D activities of NASA are presented. These briefs emphasize information considered likely to be transferrable across industrial, regional, or disciplinary lines and are issued to encourage commercial application. This index for 1985 Tech Briefs contains abstracts and four indexes: subject, personal author, originating center, and Tech Brief Number. The following areas are covered: electronic components and circuits, electronic systems, physical sciences, materials, life sciences, mechanics, machinery, fabrication technology, and mathematics and information sciences
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