31 research outputs found
2000-2001 A Little Jazz - Trio Con Brio
https://spiral.lynn.edu/conservatory_otherseasonalconcerts/1101/thumbnail.jp
A near infrared frequency comb for Y+J band astronomical spectroscopy
Radial velocity (RV) surveys supported by high precision wavelength
references (notably ThAr lamps and I2 cells) have successfully identified
hundreds of exoplanets; however, as the search for exoplanets moves to cooler,
lower mass stars, the optimum wave band for observation for these objects moves
into the near infrared (NIR) and new wavelength standards are required. To
address this need we are following up our successful deployment of an H
band(1.45-1.7{\mu}m) laser frequency comb based wavelength reference with a
comb working in the Y and J bands (0.98-1.3{\mu}m). This comb will be optimized
for use with a 50,000 resolution NIR spectrograph such as the Penn State
Habitable Zone Planet Finder. We present design and performance details of the
current Y+J band comb.Comment: Submitted to SPIE, conference proceedings 845
Near field modal noise reduction using annealed optical fiber
Incomplete and unstable mode population has long complicated the application of optical fiber for transferring star and calibration light to high precision spectrographs. The need for improved precision calibrators in support of radial velocity planet surveys has led to the introduction of coherent wavelengths sources using single mode fibers that are then coupled into multi-mode fibers, further exacerbating this problem. We explore mode scrambling in annealed optical fiber with and without agitation, as compared to that obtained using octagonal fiber and using an integrating sphere. We observe improved scrambling with annealed fibers compared to conventional and octagonal fibers
The Cosmic Origins Spectrograph
The Cosmic Origins Spectrograph (COS) is a moderate-resolution spectrograph with unprecedented sensitivity that was installed into the Hubble Space Telescope (HST) in May 2009, during HST Servicing Mission 4 (STS-125). We present the design philosophy and summarize the key characteristics of the instrument that will be of interest to potential observers. For faint targets, with flux F(sub lambda) approximates 1.0 X 10(exp -14) ergs/s/cm2/Angstrom, COS can achieve comparable signal to noise (when compared to STIS echelle modes) in 1-2% of the observing time. This has led to a significant increase in the total data volume and data quality available to the community. For example, in the first 20 months of science operation (September 2009 - June 2011) the cumulative redshift pathlength of extragalactic sight lines sampled by COS is 9 times that sampled at moderate resolution in 19 previous years of Hubble observations. COS programs have observed 214 distinct lines of sight suitable for study of the intergalactic medium as of June 2011. COS has measured, for the first time with high reliability, broad Lya absorbers and Ne VIII in the intergalactic medium, and observed the HeII reionization epoch along multiple sightlines. COS has detected the first CO emission and absorption in the UV spectra of low-mass circumstellar disks at the epoch of giant planet formation, and detected multiple ionization states of metals in extra-solar planetary atmospheres. In the coming years, COS will continue its census of intergalactic gas, probe galactic and cosmic structure, and explore physics in our solar system and Galaxy
Stellar Spectroscopy in the Near-infrared with a Laser Frequency Comb
The discovery and characterization of exoplanets around nearby stars is
driven by profound scientific questions about the uniqueness of Earth and our
Solar System, and the conditions under which life could exist elsewhere in our
Galaxy. Doppler spectroscopy, or the radial velocity (RV) technique, has been
used extensively to identify hundreds of exoplanets, but with notable
challenges in detecting terrestrial mass planets orbiting within habitable
zones. We describe infrared RV spectroscopy at the 10 m Hobby-Eberly telescope
that leverages a 30 GHz electro-optic laser frequency comb with nanophotonic
supercontinuum to calibrate the Habitable Zone Planet Finder spectrograph.
Demonstrated instrument precision <10 cm/s and stellar RVs approaching 1 m/s
open the path to discovery and confirmation of habitable zone planets around
M-dwarfs, the most ubiquitous type of stars in our Galaxy
The Cosmic Origins Spectrograph
The Cosmic Origins Spectrograph (COS) is a moderate-resolution spectrograph
with unprecedented sensitivity that was installed into the Hubble Space
Telescope (HST) in May 2009, during HST Servicing Mission 4 (STS-125). We
present the design philosophy and summarize the key characteristics of the
instrument that will be of interest to potential observers. For faint targets,
with flux F_lambda ~ 1.0E10-14 ergs/s/cm2/Angstrom, COS can achieve comparable
signal to noise (when compared to STIS echelle modes) in 1-2% of the observing
time. This has led to a significant increase in the total data volume and data
quality available to the community. For example, in the first 20 months of
science operation (September 2009 - June 2011) the cumulative redshift
pathlength of extragalactic sight lines sampled by COS is 9 times that sampled
at moderate resolution in 19 previous years of Hubble observations. COS
programs have observed 214 distinct lines of sight suitable for study of the
intergalactic medium as of June 2011. COS has measured, for the first time with
high reliability, broad Lya absorbers and Ne VIII in the intergalactic medium,
and observed the HeII reionization epoch along multiple sightlines. COS has
detected the first CO emission and absorption in the UV spectra of low-mass
circumstellar disks at the epoch of giant planet formation, and detected
multiple ionization states of metals in extra-solar planetary atmospheres. In
the coming years, COS will continue its census of intergalactic gas, probe
galactic and cosmic structure, and explore physics in our solar system and
Galaxy.Comment: 17 pages, 15 figure
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Research and Design of a Routing Protocol in Large-Scale Wireless Sensor Networks
无线传感器网络,作为全球未来十大技术之一,集成了传感器技术、嵌入式计算技术、分布式信息处理和自组织网技术,可实时感知、采集、处理、传输网络分布区域内的各种信息数据,在军事国防、生物医疗、环境监测、抢险救灾、防恐反恐、危险区域远程控制等领域具有十分广阔的应用前景。 本文研究分析了无线传感器网络的已有路由协议,并针对大规模的无线传感器网络设计了一种树状路由协议,它根据节点地址信息来形成路由,从而简化了复杂繁冗的路由表查找和维护,节省了不必要的开销,提高了路由效率,实现了快速有效的数据传输。 为支持此路由协议本文提出了一种自适应动态地址分配算——ADAR(AdaptiveDynamicAddre...As one of the ten high technologies in the future, wireless sensor network, which is the integration of micro-sensors, embedded computing, modern network and Ad Hoc technologies, can apperceive, collect, process and transmit various information data within the region. It can be used in military defense, biomedical, environmental monitoring, disaster relief, counter-terrorism, remote control of haz...学位:工学硕士院系专业:信息科学与技术学院通信工程系_通信与信息系统学号:2332007115216