93,326 research outputs found
Climate Resilient & Equitable Water Systems Capital Scan
Climate change is affecting water supply, water management and the health of communities in U.S. cities. Changes in the timing, frequency and intensity of precipitation are placing stress on the built and natural systems that provide fresh water, manage storm water, and treat wastewater. Droughts are shrinking the water supply; heavy rainfall overburdens storm water systems, causing flooding in homes and neighborhoods. Low-income people and communities of color are often the most vulnerable to climate change, living in low-lying areas and lacking the resources to adapt and cope with challenges associated with these patterns.The cumulative impact of climate change on water resources not only leads to a reduction in water quality and the destruction of homes and property, but it can also be a threat to public health, force relocation of communities and cause economic harm.The vision of Kresge's Environment Program is to help communities build resilience in the face of climate change. We believe that cities are central to action on climate change and equity must be a fundamental part of our work in climate adaptation, climate mitigation and building social cohesion
Adaptive thermal compensation of test masses in advanced LIGO
As the first generation of laser interferometric gravitational wave detectors
near operation, research and development has begun on increasing the
instrument's sensitivity while utilizing the existing infrastructure. In the
Laser Interferometer Gravitational Wave Observatory (LIGO), significant
improvements are being planned for installation in ~2007, increasing strain
sensitivity through improved suspensions and test mass substrates, active
seismic isolation, and higher input laser power. Even with the highest quality
optics available today, however, finite absorption of laser power within
transmissive optics, coupled with the tremendous amount of optical power
circulating in various parts of the interferometer, result in critical
wavefront deformations which would cripple the performance of the instrument.
Discussed is a method of active wavefront correction via direct thermal
actuation on optical elements of the interferometer. A simple nichrome heating
element suspended off the face of an affected optic will, through radiative
heating, remove the gross axisymmetric part of the original thermal distortion.
A scanning heating laser will then be used to remove any remaining
non-axisymmetric wavefront distortion, generated by inhomogeneities in the
substrate's absorption, thermal conductivity, etc. A proof-of-principle
experiment has been constructed at MIT, selected data of which are presented.Comment: 11 pages, 7 figures, submitted to Classical and Quantum Gravit
The NASA Spitzer Space Telescope
The National Aeronautics and Space Administration's Spitzer Space Telescope (formerly the Space Infrared Telescope Facility) is the fourth and final facility in the Great Observatories Program, joining Hubble Space Telescope (1990), the Compton Gamma-Ray Observatory (1991–2000), and the Chandra X-Ray Observatory (1999). Spitzer, with a sensitivity that is almost three orders of magnitude greater than that of any previous ground-based and space-based infrared observatory, is expected to revolutionize our understanding of the creation of the universe, the formation and evolution of primitive galaxies, the origin of stars and planets, and the chemical evolution of the universe. This review presents a brief overview of the scientific objectives and history of infrared astronomy. We discuss Spitzer's expected role in infrared astronomy for the new millennium. We describe pertinent details of the design, construction, launch, in-orbit checkout, and operations of the observatory and summarize some science highlights from the first two and a half years of Spitzer operations. More information about Spitzer can be found at http://spitzer.caltech.edu/
Recommended from our members
Selective Laser Melting of Biocompatible Metals for Rapid Manufacturing of Medical Parts
In recent years, digitizing and automation have gained an important place in fabrication of
medical parts. Rapid Manufacturing could be very suitable for medical applications due to their
complex geometry, low volume and strong individualization. The presented study investigates
the possibility to produce medical or dental parts by Selective Laser Melting (SLM). The SLMprocess is optimized and fully characterized for two biocompatible metal alloys: TiAl6V4 and
CoCrMo. This paper reports on mechanical and chemical properties and discusses geometrical
feasibility including accuracy and surface roughness. The potential of SLM as medical
manufacturing technique is proved by a developed procedure to fabricate frameworks for
complex dental prostheses.Mechanical Engineerin
STATUS OF CHECKOUT TECHNOLOGY
The author describes the various types of computerized checkout systems available and the relative merits of these systems.Agribusiness,
Optimized Herschel/PACS photometer observing and data reduction strategies for moving solar system targets
The "TNOs are Cool!: A survey of the trans-Neptunian region" is a Herschel
Open Time Key Program that aims to characterize planetary bodies at the
outskirts of the Solar System using PACS and SPIRE data, mostly taken as
scan-maps. In this paper we summarize our PACS data reduction scheme that uses
a modified version of the standard pipeline for basic data reduction, optimized
for faint, moving targets. Due to the low flux density of our targets the
observations are confusion noise limited or at least often affected by bright
nearby background sources at 100 and 160\,m. To overcome these problems we
developed techniques to characterize and eliminate the background at the
positions of our targets and a background matching technique to compensate for
pointing errors. We derive a variety of maps as science data products that are
used depending on the source flux and background levels and the scientific
purpose. Our techniques are also applicable to a wealth of other Herschel solar
system photometric observations, e.g. comets and near-Earth asteroids. The
principles of our observing strategies and reduction techniques for moving
targets will also be applicable for similar surveys of future infrared space
projects.Comment: Accepted for publication in Experimental Astronom
Real-time Motion Planning For Autonomous Car in Multiple Situations Under Simulated Urban Environment
Advanced autonomous cars have revolutionary meaning for the automobile industry. While more and more companies have already started to build their own autonomous cars, no one has yet brought a practical autonomous car into the market. One key problem of their cars is lacking a reliable active real-time motion planning system for the urban environment. A real-time motion planning system makes cars can safely and stably drive under the urban environment. The final goal for this project is to design and implement a reliable real-time motion planning system to reduce accident rates in autonomous cars instead of human drivers. The real-time motion planning system includes lane-keeping, obstacle avoidance, moving car avoidance, adaptive cruise control, and accident avoidance function. In the research, EGO vehicles will be built and equipped with an image processing unit, a LIDAR, and two ultrasonic sensors to detect the environment. These environment data make it possible to implement a full control program in the real-time motion planning system. The control program will be implemented and tested in a scaled-down EGO vehicle with a scaled-down urban environment. The project has been divided into three phases: build EGO vehicles, implement the control program of the real-time motion planning system, and improve the control program by testing under the scale-down urban environment. In the first phase, each EGO vehicle will be built by an EGO vehicle chassis kit, a Raspberry Pi, a LIDAR, two ultrasonic sensors, a battery, and a power board. In the second phase, the control program of the real-time motion planning system will be implemented under the lane-keeping program in Raspberry Pi. Python is the programming language that will be used to implement the program. Lane-keeping, obstacle avoidance, moving car avoidance, adaptive cruise control functions will be built in this control program. In the last phase, testing and improvement works will be finished. Reliability tests will be designed and fulfilled. The more data grab from tests, the more stability of the real-time motion planning system can be implemented. Finally, one reliable motion planning system will be built, which will be used in normal scale EGO vehicles to reduce accident rates significantly under the urban environment.No embargoAcademic Major: Electrical and Computer Engineerin
- …