Design study for LANDSAT D attitude control system

A design and performance evaluation is presented for the LANDSAT D attitude control system (ACS). Control and configuration of the gimballed Ku-band antenna system for communication with the tracking and data relay satellite (TDRS). Control of the solar array drive considered part of the ACS is also addressed

Hexapod Design For All-Sky Sidereal Tracking

In this paper we describe a hexapod-based telescope mount system intended to provide sidereal tracking for the Fly's Eye Camera project -- an upcoming moderate, 21"/pixel resolution all-sky survey. By exploiting such a kind of meter-sized telescope mount, we get a device which is both capable of compensating for the apparent rotation of the celestial sphere and the same design can be used independently from the actual geographical location. Our construction is the sole currently operating hexapod telescope mount performing dedicated optical imaging survey with a sub-arcsecond tracking precision.Comment: Accepted for publication in PASP, 10 page

Reliable fusion of ToF and stereo depth driven by confidence measures

In this paper we propose a framework for the fusion of depth data produced by a Time-of-Flight (ToF) camera and stereo vision system. Initially, depth data acquired by the ToF camera are upsampled by an ad-hoc algorithm based on image segmentation and bilateral filtering. In parallel a dense disparity map is obtained using the Semi- Global Matching stereo algorithm. Reliable confidence measures are extracted for both the ToF and stereo depth data. In particular, ToF confidence also accounts for the mixed-pixel effect and the stereo confidence accounts for the relationship between the pointwise matching costs and the cost obtained by the semi-global optimization. Finally, the two depth maps are synergically fused by enforcing the local consistency of depth data accounting for the confidence of the two data sources at each location. Experimental results clearly show that the proposed method produces accurate high resolution depth maps and outperforms the compared fusion algorithms

Phase 1 of the near term hybrid passenger vehicles development program. Appendix A: Mission analysis and performance specification studies, volume 1

Applicable data was categorized and processed according to vehicle usage and trip parameters with consideration of payload (cargo, people, size) and driving cycles. A mission that maximizes the fuel potential savings for the total 1985 vehicle fleet was selected. Mission requirements that have a bearing on conventional and hybrid vehicle performance and characteristics were identified and formulated and a reference ICE vehicle was selected that meets or exceeds all requirements while maintaining within applicable constraints. Specifications for vehicle performance were established based on mission requirements, mission related vehicle characteristics, and fuel consumption

Long-lived Giant Number Fluctuations in a Swarming Granular Nematic

Coherently moving flocks of birds, beasts or bacteria are examples of living matter with spontaneous orientational order. How do these systems differ from thermal equilibrium systems with such liquid-crystalline order? Working with a fluidized monolayer of macroscopic rods in the nematic liquid crystalline phase, we find giant number fluctuations consistent with a standard deviation growing linearly with the mean, in contrast to any situation where the Central Limit Theorem applies. These fluctuations are long-lived, decaying only as a logarithmic function of time. This shows that flocking, coherent motion and large-scale inhomogeneity can appear in a system in which particles do not communicate except by contact.Comment: This is the author's version of the work. It is posted here by permission of the AAAS. The definitive version is to appear in SCIENC

Guide for users of the National Transonic Facility

The National Transonic Facility (NTF) is a fan-driven, closed-circuit, continuous flow, pressurized wind tunnel. The test section is 2.5 m x 2.5 m and 7.62 m long with a slotted-wall configuration. The NTF will have a Mach number range from 0.2 to 1.2, with Reynolds number up to 120 10 to the sixth power at Mach 1 (based on a reference length of 0.25 m). The pressure range for the facility will be from 1 to about 9 bars (1 ban = 100 kPa), and the temperature can be varied from 340 to 78 K. This report provides potential users of the NTF with the information required for preliminary planning to test programs and for preliminary layout of models and model supports which may be used in such programs

An inventory of aeronautical ground research facilities. Volume 1: Wind tunnels

A survey of wind tunnel research facilities in the United States is presented. The inventory includes all subsonic, transonic, and hypersonic wind tunnels operated by governmental and private organizations. Each wind tunnel is described with respect to size, mechanical operation, construction, testing capabilities, and operating costs. Facility performance data are presented in charts and tables

Deep Level Transient Spectroscopy (DLTS) System And Method

A computer-based deep level transient spectroscopy (DLTS) system (10) efficiently digitizes and analyzes capacitance and conductance transients acquired from a test material (13) by conventional DLTS methods as well as by several transient methods, including a covariance method of linear predictive modeling. A unique pseudo-logarithmic data storage scheme allows each transient to be tested at more than eleven different rates, permitting three to five decades of time constants τ to be observed during each thermal scan, thereby allowing high resolution of closely spaced defect energy levels. The system (10) comprises a sensor (12) for detecting capacitance and/or conductance transients, a digitizing mechanism (14) for digitizing the capacitance and/or conductance transients, preamplifiers (16a, 16b) for filtering, amplifying, and for forwarding the transients to the digitizing mechanism (14), a pulse generator (18) for supplying a filling pulse to the test material (13) in a cryostat (24), a trigger conditioner for coordinating the timing between the digitizing mechanism (14) and the pulse generator (18), and a temperature controller (26) for changing the temperature of the cryostat (24).Georgia Tech Research Corporatio