Seasat. Volume 3: Ground systems

The Seasat Project was a feasibility demonstration of the use of orbital remote sensing for global ocean observation. The satellite was launched in June of 1978 and was operated successfully until October 1978. A massive electrical failure occurred in the power system, terminating the mission prematurely. The ground systems using during the mission life are discussed. Descriptions of the operating organization, the system elements, and the testing program are included. The various phases of the mission: launch and orbit insertion; cruise; and calibration are discussed. A special section is included on the orbit maneuver activites. Operations during the satellite failure are reviewed and summarized

A study of the variability of dynamics and temperatures near the mesopause from observations of the hydroxyl (OH) Meinel band emission

The hydroxyl (OH) molecule has a significant role in the energy budget of the mesosphere. It can also be an important diagnostic of the physical and dynamical nature in the mesopause region since the OH Meinel emission bands contain signatures of the temperature and wind velocity of the mesopause region, around 85 km altitude. In this study the OH (6,2) emission line (843.0 nm) is investigated using a ground-based Fabry-Perot interferometer. A computer simulation has been carried out to predict the performance of the Fabry-Perot interferometer. The instrument function is obtained using a He-Ne laser at the wavelength of 632.8 nm, and is converted to the OH wavelength of 843.0 nm. The theoretical response of the interferometer to the OH emission is calculated by convolving a modelled OH spectrum and the converted laser calibration profile. This is compared with experimental data by using a non-linear least-squares method to extract Doppler temperature and velocity. Temperature and wind velocity errors are calculated analytically and numerically to increase credibility, and both show a good agreement. Systematic peak drift and broadening of instrument function have been found, which can be compensated for by using properly positioned instrument functions, and monitoring calibration lamp broadenings and subtracting the broadening effect from the instrument function. For tidal analysis, a combined Fourier and least-squares technique has been developed to overcome the problem that observation time is shorter than longer tidal period (diurnal and semidiurnal tide) in summer. In addition, a scheme for detecting and rejecting bad data, due to bad weather and system failure etc., has been also developed and which enables to save a great deal of data for a long term analysis. All these efforts are important for the long term analysis to achieve precise result and higher data density. An annual variation of temperature in the mesopause region has been confirmed. In addition, sudden mesospheric coolings by ∼25 K have been found during the months of January and February. These periods of strong cooling appear to be connected with stratospheric warming events. From the one month averaged hourly mean temperature, tidal variations on OH temperature are found as reducing error bound and smoothing out of uncorrelated fluctuations. The seasonal variations of amplitude and phases are obtained using the combined Fourier and least-squares method. Winter has the maximum amplitudes of ∼15 K, while summer has the minimum amplitudes of ∼2 K. The correlation between OH temperature and intensity has been investigated by introducing [eta] parameter and squared coherency spectrum. Unlike O2 emission, OH temperature and intensity are out-of-phase for the most of time. Mesopause wind velocities are also obtained from the measurement of Doppler shift of OH emission spectra. The meridional wind near the mesopause is usually southward (equatorward) throughout the summer period. This might be the evidence of a systematic inter-hemispheric circulation from the summer to the winter hemisphere. The zonal wind near the mesopause shows a semi-annual variation. This phenomenon may be explained in terms of momentum transfer from gravity waves which are filtered and modulated by the semi-annual zonal wind in the stratosphere. For tidal analysis, one month averaged hourly mean wind velocities are calculated and the combined Fourier and least-squares method is also applied. The data from almost every month show tidal wind variations, however in summer and autumn there are larger amplitudes (∼20 m/sec), while winter shows smaller amplitudes (∼3 m/sec). In phases, it is difficult to find any structure except that the winter phase advances the summer phase by 5 hours in semidiurnal tide

Video data modulation study, volume 1 Final report

Video data modulation technique

Thermal stress effects in intermetallic matrix composites

Intermetallic matrix composites develop residual stresses from the large thermal expansion mismatch (delta-alpha) between the fibers and matrix. This work was undertaken to: establish improved techniques to measure these thermal stresses in IMC's; determine residual stresses in a variety of IMC systems by experiments and modeling; and, determine the effect of residual stresses on selected mechanical properties of an IMC. X ray diffraction (XRD), neutron diffraction (ND), synchrotron XRD (SXRD), and ultrasonics (US) techniques for measuring thermal stresses in IMC were examined and ND was selected as the most promising technique. ND was demonstrated on a variety of IMC systems encompassing Ti- and Ni-base matrices, SiC, W, and Al2O3 fibers, and different fiber fractions (Vf). Experimental results on these systems agreed with predictions of a concentric cylinder model. In SiC/Ti-base systems, little yielding was found and stresses were controlled primarily by delta-alpha and Vf. In Ni-base matrix systems, yield strength of the matrix and Vf controlled stress levels. The longitudinal residual stresses in SCS-6/Ti-24Al-llNb composite were modified by thermomechanical processing. Increasing residual stress decreased ultimate tensile strength in agreement with model predictions. Fiber pushout strength showed an unexpected inverse correlation with residual stress. In-plane shear yield strength showed no dependence on residual stress. Higher levels of residual tension led to higher fatigue crack growth rates, as suggested by matrix mean stress effects

Third International Symposium on Space Mission Operations and Ground Data Systems, part 1

Under the theme of 'Opportunities in Ground Data Systems for High Efficiency Operations of Space Missions,' the SpaceOps '94 symposium included presentations of more than 150 technical papers spanning five topic areas: Mission Management, Operations, Data Management, System Development, and Systems Engineering. The papers focus on improvements in the efficiency, effectiveness, productivity, and quality of data acquisition, ground systems, and mission operations. New technology, techniques, methods, and human systems are discussed. Accomplishments are also reported in the application of information systems to improve data retrieval, reporting, and archiving; the management of human factors; the use of telescience and teleoperations; and the design and implementation of logistics support for mission operations

High-Throughput Automated Multi-Target Super-resolution Imaging

Super-resolution microscopy techniques developed through the past few decades enable us to surpass the classical diffraction limit of light, and thus open new doors to investigate the formerly inaccessible world of nanometer-sized objects. Most importantly, by using super-resolution microscopy, one can visualize sub-cellular structures in the range of 10 to 200 nm. At this range, we can investigate exciting problems in biology and medicine by visualizing protein-protein interactions and spatiotemporal analysis of structures of interest on the surface or inside cells. These techniques (collectively known as nanoscopy) have a high impact on understanding and solving biological questions. This dissertation starts with a brief and general description of current super-resolution techniques and then moves toward a multi-target super-resolution imaging strategy using sequential imaging that has benefits over conventional multi-color imaging methods. Sequential microscopy takes advantage of the photo-physical properties of the most suitable dye for a particular technique to achieve the optimal and consistent resolution for each of multiple targets of imaging. For example, for dSTORM imaging, this is currently AlexaFluor647.\ Sequential dSTROM has an advantage for multi-target imaging due to having a single imaging channel which avoids dealing with differential aberration-problems between multiple emission paths unlike other multi-color imaging based methods. We show that sequential imaging method can be facilitated using automated imaging. In this dissertation, a sequential microscope is designed, calibrated, and tested on multiple structures. We show that it can automatically re-find the position of each initially registered cell and can account for sample drift through an entire experiment. The microscope has been used in multiple collaborations with other groups to investigate biological problems of interest. Two labeling strategies that facilitate sequential imaging are described.\ The first strategy is DNA-strand-displacement , which allows imaging of multiple structures in a controlled and time-efficient binding-unbinding scenario. The second strategy is imaging with the small, actin binding peptide Lifeact. Finally, future directions and suggestions are made about how we can further improve the microscope. In the Appendix I provide a guide on how to use and troubleshoot the microscope, how to measure the efficiency of the microscope, as well as how to fix and label cells for optimal imaging and how to prepare various imaging buffers

An architecture for intelligent health assessment enabled IEEE 1451 compliant smart sensors

As systems become increasingly complex and costly, potential failure mechanisms and indicators are numerous and difficult to identify, while the cost of loss is very expensive - human lives, replacement units, and impacts to national security. In order to ensure the safety and long-term reliability of vehicles, structures, and devices attention must be directed toward the assessment and management of system health. System health is the key component that links data, information, and knowledge to action. Integrated Systems Health Management (ISHM) doctrine calls for comprehensive real-time health assessment and management of systems where the distillation of raw data into information takes place within sensors and actuators. This thesis develops novel field programmable health assessment capability for sensors and actuators in ISHM. Health assessment and feature extraction algorithms are implemented on a sensor or actuator through the Embedded Routine Manager (ERM) API. Algorithms are described using Health Electronic Datasheets (HEDS) to provide more flexible run-time operation. Interfacing is accomplished through IEEE Standard 1451 for Smart Sensors and Actuators, connecting ISHM with the instrumentation network of the future. These key elements are validated using exemplar algorithms to detect noise, spike, and flat-line events onboard the ISHM enabled Methane Thruster Testbed Project (MTTP) at NASA Stennis Space Center in Mississippi

Timely and reliable evaluation of the effects of interventions: a framework for adaptive meta-analysis (FAME)

Most systematic reviews are retrospective and use aggregate data AD) from publications, meaning they can be unreliable, lag behind therapeutic developments and fail to influence ongoing or new trials. Commonly, the potential influence of unpublished or ongoing trials is overlooked when interpreting results, or determining the value of updating the meta-analysis or need to collect individual participant data (IPD). Therefore, we developed a Framework for Adaptive Metaanalysis (FAME) to determine prospectively the earliest opportunity for reliable AD meta-analysis. We illustrate FAME using two systematic reviews in men with metastatic (M1) and non-metastatic (M0)hormone-sensitive prostate cancer (HSPC)