CFRP truss for the CCAT 25 m diameter submillimeter-wave telescope

CCAT will be a 25 m diameter submillimeter-wave telescope that will operate inside a dome located on Cerro Chajnantor in the Atacama Desert. The telescope must have high aperture efficiency at a wavelength of 350 microns and good performance out to a wavelength of 200 microns. A conceptual design for a carbon fiber reinforced plastic (CFRP) truss and primary reflector support truss has been developed. This design yields a telescope with a net �½ wave front error of <10 microns using a lookup table to adjust the segment actuators to compensate for gravitational deflections. Minor corrections may be required to compensate for the expected 20 C temperature excursions. These can be handled using a coarse lookup table

Visual modulation transfer function as a predictor of acuity

The use of Fourier and modulation transfer techniques implies the ability to characterize an optical system and predict the output resulting from various inputs. In this study, the optical system is defined as a projection system, rear projection screen, and the human eye. A determination of modulation thresholds of visibility for a series of sinusoidal (in transmittance) test objects results after some manipulation in the modulation transfer function of the complete system. This result is then used to predict the subject\u27s ability to resolve conventional acuity challenges. These conventional test objects are then manufactured for projection in the system. Correlation between predicted acuity and observed acuity as tested may now be determined. The result indicates the degree to which optical designers may rely on modulation transfer and fourier techniques to predict the visual performance of a system. Presentation of targets was made using a modified slide projector. Changes in modulation were achieved by addition of a veiling glare projector. Subject response consisted of a forced choice, yes or no, as to whether modulation was perceived in the field of view. Thresholds of perception were defined as that modulation correctly observed 50% of the time. Two-bar targets were produced, and characterized by microdensitometer traces. Using the discrete fourier transform, these targets were convolved with the spread function defined by the M.T.F. Resulting absorption profiles permitted an estimate of image degra dation. When essential details of the object were lost it was predicted that visual resolution would fail. The accuracy of this prediction was tested by presentation of the two bar targets to the subject. Results indicate that while modulation transfer and fourier techniques permit rapid assessment of an optical system, that many factors affect subjective visual response, In testing it was found that while a high degree of correla tion exists between predicted resolution and actual resolution, variability inherent in threshold measurement precludes precision in prediction

CCAT

Star formation, which drives the evolution of baryonic matter in the universe, occurs in the densest regions of the interstellar medium. As a result much of the emergent short wavelength radiation, UV to near IR, is absorbed by intervening dust and reradiated at longer wavelengths, far IR and subillimeter. Indeed the energy density of post primordial extragalactic light is divided equally between these short and long wavelengths, indicating equal amounts of radiation have passed through dusty and optically transparent environments over cosmic time. Comprehensive understanding of the processes of galaxy, star, and planetary formation requires, therefore, high sensitivity and high angular resolution observations, particularly surveys, in the far IR and submillimeter. A consortium led by Cornell and Caltech with JPL is now jointly planning the construction of a 25 m diameter telescope for submillimeter astronomy on a high mountain in northern Chile. This CCAT will combine high sensitivity, a wide field of view, and a broad wavelength range to provide an unprecedented capability for deep, large area, multi-color submillimeter surveys to complement narrow field, high resolution studies with ALMA. CCAT observations will address fundamental themes in contemporary astronomy, notably the formation and evolution of galaxies, the nature of the dark matter and dark energy that comprise most of the content of the universe, the formation of stars and planets, the conditions in circumstellar disks, and the conditions during the early history of the Solar system. The candidate CCAT site, at 5600m in northern Chile, enjoys superb observing conditions. To accommodate large format bolometer cameras, CCAT is designed with a 20 arcmin field of view. CCAT will incorporate closed loop active control of its segmented primary mirror to maintain a half wavefront error of 10 μm rms or less for the entire telescope. Instrumentation under consideration includes both short (650 μm–200 μm) and long (2 mm–750 μm) wavelength bolometer cameras, direct detection spectrometers, and heterodyne receiver arrays. In addition to Cornell and Caltech with JPL, the University of Colorado, the Universities of British Columbia and of Waterloo, the UK Astronomy Technology Centre on behalf of the UK community, and the Universities of Cologne and of Bonn have joined the CCAT consortium. When complete, CCAT will be the largest and most sensitive facility of its class as well as the highest altitude astronomical facility on Earth

The Cornell Caltech Atacama Telescope status and technical progress

Five partners have currently joined a Consortium to develop the Cornell Caltech Atacama Telescope (CCAT.) Included are Cornell University, the California Institute of Technology (Caltech), the University of Colorado at Boulder, the United Kingdom as represented by the Astronomy Technology Centre (ATC), and Canada as represented by the Universities of British Columbia and Waterloo. This consortium has continued work toward the design of the telescope and instrumentation, pursued fund raising, and further developed the science case for CCAT. An Engineering Design Phase is being planned for 2009-2011 with construction planned to begin shortly thereafter. CCAT continues as a wide field (20 arc min) FOV telescope operating from a shortest wavelength of 200µ. Testing has continued near the summit of Cerro Chajnantor in the Atacama Region of Chile above 5600 meters altitude and data indicates significantly lower water vapor in the seeing column than measured at the ALMA site on the plateau below. Work over the past two years has included research on manufacturing methods for optical segments, extensive study of mirror alignment sensing and control techniques, additional concepts for major structures, and further development of instrumentation

Cornell Caltech Atacama Telescope (CCAT): a 25 m aperture telescope above 5000 m altitude

Cornell, California Institute of Technology (Caltech), and Jet Propulsion Lab (JPL) have joined together to study development of a 25 meter sub-millimeter telescope (CCAT) on a high peak in the Atacama region of northern Chile, where the atmosphere is so dry as to permit observation at wavelengths as short as 200 μm. The telescope is designed to deliver high efficiency images at that wavelength with a total one-half wavefront error of about 10 μm. With a 20 arc min field of view, CCAT will be able to accommodate large format bolometer arrays and will excel at carrying out surveys as well as resolving structures to the 2 arc sec resolution level. The telescope will be an ideal complement to ALMA. Initial instrumentation will include both a wide field bolometer camera and a medium resolution spectrograph. Studies of the major telescope subsystems have been performed as part of an initial Feasibility Concept Study. Novel aspects of the telescope design include kinematic mounting and active positioning of primary mirror segments, high bandwidth secondary mirror segment motion control for chopping, a Calotte style dome of 50 meter diameter, a mount capable of efficient scanning modes of operation, and some new approaches to panel manufacture. Analysis of telescope performance and of key subsystems will be presented to illustrate the technical feasibility and pragmatic cost of CCAT. Project plans include an Engineering Concept Design phase followed by detailed design and development. First Light is planned for early 2012

Research on Pedestrian Detection and Tracking in Intelligent Video Surveillance

智能视频监控与人们的生活联系越来越紧密，已经渗透到人们生活的各个方面，如交通流量统计、企业安防、刑侦、银行监控、医院等都可以看到视频监控的影响。智能视频监控作为模式识别领域的重要分支，主要研究的是视频中的运动物体，对运动目标进行检测、识别和跟踪。而人是视频中的人们最关心的运动目标，通过对行人的行为分析，给监控者提供可靠、及时的信息，为人们对异常事件做出快速的反应提供依据。视频中行人的检测与跟踪技术是这一切的基础，只有有了准确、鲁棒的行人检测与跟踪算法，才能为后面的人体动作识别、人群异常事件检测等提供可靠的保障。因此研究视频中的行人检测与跟踪算法具有重要的现实意义。本文总结分析了常用的视频中的目...Intelligent video surveillance is an important research direction in the field of computer vision, its wide range of applications, such as many aspects of security, traffic management, banks, hospitals, etc., has important significance. It is through the analysis of video sequences for detection, identification and tracking of objects in the scene to be monitored and found to provide a basis so th...学位：工学硕士院系专业：信息科学与技术学院_计算机应用技术学号：2302011115303

The Cornell Caltech Atacama Telescope status and technical progress

Five partners have currently joined a Consortium to develop the Cornell Caltech Atacama Telescope (CCAT.) Included are Cornell University, the California Institute of Technology (Caltech), the University of Colorado at Boulder, the United Kingdom as represented by the Astronomy Technology Centre (ATC), and Canada as represented by the Universities of British Columbia and Waterloo. This consortium has continued work toward the design of the telescope and instrumentation, pursued fund raising, and further developed the science case for CCAT. An Engineering Design Phase is being planned for 2009-2011 with construction planned to begin shortly thereafter. CCAT continues as a wide field (20 arc min) FOV telescope operating from a shortest wavelength of 200µ. Testing has continued near the summit of Cerro Chajnantor in the Atacama Region of Chile above 5600 meters altitude and data indicates significantly lower water vapor in the seeing column than measured at the ALMA site on the plateau below. Work over the past two years has included research on manufacturing methods for optical segments, extensive study of mirror alignment sensing and control techniques, additional concepts for major structures, and further development of instrumentation

A Better Index of Body Adiposity

Obesity is a growing problem in the United States and throughout the world. It is a risk factor for many chronic diseases. The BMI has been used to assess body fat for almost 200 years. BMI is known to be of limited accuracy, and is different for males and females with similar %body adiposity. Here, we define an alternative parameter, the body adiposity index (BAI = ((hip circumference)/((height)1.5)–18)). The BAI can be used to reflect %body fat for adult men and women of differing ethnicities without numerical correction. We used a population study, the “BetaGene” study, to develop the new index of body adiposity. %Body fat, as measured by the dual-energy X-ray absorptiometry (DXA), was used as a “gold standard” for validation. Hip circumference (R = 0.602) and height (R = −0.524) are strongly correlated with %body fat and therefore chosen as principal anthropometric measures on which we base BAI. The BAI measure was validated in the “Triglyceride and Cardiovascular Risk in African-Americans (TARA)” study of African Americans. Correlation between DXA-derived %adiposity and the BAI was R = 0.85 for TARA with a concordance of C_b = 0.95. BAI can be measured without weighing, which may render it useful in settings where measuring accurate body weight is problematic. In summary, we have defined a new parameter, the BAI, which can be calculated from hip circumference and height only. It can be used in the clinical setting even in remote locations with very limited access to reliable scales. The BAI estimates %adiposity directly