Engineering topics
Joshi, S.
Publications and source records attributed to Joshi, S..
LO Peg: Surface Differential Rotation, Flares, and Spot-Topographic Evolution
Using the wealth of ∼24 yr multiband data, we present an in-depth study of the star-spot cycles, surface differential rotations (SDR), optical flares, evolution of star-spot distributions, and coronal activities on the surface of young, single, main-sequence, ultrafast rotator LO Peg. From the long-term V-band photometry, we derive rotational period of LO Peg to be 0.4231 +/- 0.0001 d. Using the seasonal variations on the rotational period, the SDR pattern is investigated, and shows a solar-like pattern of SDR. A cyclic pattern with period of ∼2.7 yr appears to be present in rotational period variation. During the observations, 20 optical flares are detected with a flare frequency of ∼1 flare per two days and with flare energy of ∼10(exp 31-34) erg. The surface coverage of cool spots is found to be in the range of ∼9-26 per cent. It appears that the high- and low-latitude spots are interchanging their positions. Quasi-simultaneous observations in X-ray, UV, and optical photometric bands show a signature of an excess of X-ray and UV activities in spotted regions.
Robot work crews for planetary outposts: close cooperation and coordination of multiple mobile robots
We report on the development of cooperating multiple robots. This work builds from our earlier research on autonomous planetary rovers and robot arms.
Tightly-coupled coordination of multi-robot systems for mars exploration
Site construction operations by autonomous robotic systems are essential for a sustained robotic presence and human habitation on mars.
Multilevel Adaptation for Autonomous Mobile Robot Formations
This paper studies adaptive behavior within multiagent autonomous robot formation-keeping.
MURKY ACS Software to Determine 3 Axis Attitude Without the Star Tracker
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Functional and structural mapping of human cerebral cortex: solutions are in the surfaces
No abstract available
The Need for a Systems Perspective in Control Theory and Practice
Control systems have had a profound impact on society as theories, techniques, and algorithms have migrated from the laboratory to thousands of products. As the control community continues to improve its solutions, ideas are being generated for a new era of applicationws that are fundamentally different from their predecessors.
Brain segmentation and the generation of cortical surfaces
This paper describes methods for white matter segmentation in brain images and the generation of cortical surfaces from the segmentations. We have developed a system that allows a user to start with a brain volume, obtained by modalities such as MRI or cryosection, and constructs a complete digital representation of the cortical surface. The methodology consists of three basic components: local parametric modeling and Bayesian segmentation; surface generation and local quadratic coordinate fitting; and surface editing. Segmentations are computed by parametrically fitting known density functions to the histogram of the image using the expectation maximization algorithm [DLR77]. The parametric fits are obtained locally rather than globally over the whole volume to overcome local variations in gray levels. To represent the boundary of the gray and white matter we use triangulated meshes generated using isosurface generation algorithms [GH95]. A complete system of local parametric quadratic charts [JWM+95] is superimposed on the triangulated graph to facilitate smoothing and geodesic curve tracking. Algorithms for surface editing include extraction of the largest closed surface. Results for several macaque brains are presented comparing automated and hand surface generation. Copyright 1999 Academic Press.
Damper Placement for Spaceborne Interferometers Using H(inf)-Norm, Genetic Algorithm, and Simulated Annealing, Optimization
A general methodology for damper placement in spaceborne interferometers is introduced.
Overview of the MicroPrecision Interferometer Testbed
This paper gives an overview of the Micro-Precision Interferometer (MIP) testbed and its major achievements to date related to mitigating risk for future spaceborne optical interferometer missions.
Lessons Learned form Multiple Fidelity Modeling of Ground Interferometer Testbeds
The MicroPrecision Interferometer Testbed (MIP) at JPL is a dynamically and dimensionally representative hardware model of a future spaceborne optical interferometer.
Use of the Microprecision Interferometer Testbed for Developing Control Technology for Spaceborne Optical Interferometer Missions
This paper describes the Micro-Precision Interferometer (MPI) testbed and its major achievements to date related to mitigating risk for future spaceborne optical interferometer missions.