Applications of Mininum Variance Reduced-State Estimators

This paper presents an algorithm for a class of suitably constrained reduced-order filters which minimize the variance of the estimated variables. The algorithm generates both the filter gain history and the true estimation error covariance. The algorithm provides a quantitative criterion which can be used to measure the performance of any reduced-order estimator. Both continuous and discrete estimators are considered. Several examples are treated including an application of the technique to a hybrid navigation system of high order.     

Data From the Precision Solar Photometric Telescope (Pspt) in Hawaii From March 1998 to March 1999

Two Precision Solar Photometric Telescopes (PSPT) designed and built at the U.S. National Solar Observatory (NSO) are in operation in Rome and Hawaii. A third PSPT is now in operation the NSO at Sunspot, NM. The PSPT system records full disk solar images at three wavelengths: K line at 393.3 nm and two continua at 409 nm and 607 nm throughout the observing day. We currently study properties of limb darkening, sunspots, and network in these images with particular emphasis on data taken in July and September 1998. During this period, the number of observations per month was high enough to show directional properties of the radiation field surrounding sunspots. We show examples of our PSPT images and describe our study of bright rings around sunspots.     

Precursory signature of several major earthquakes studied using 40 kHz low frequency signal

To investigate the precursory signature of earthquakes on low frequency (LF) signal propagation, six earthquakes, having magnitude greater than equal to 6.5 and depth less than equal to 30 km, are being studied. The base line level of 40 kHz signal, transmitted from JJY station, Japan, is analysed with respect to V_d statistical parameter. Results show that the V_d parameter values starts fluctuating from its ambient levels before and during the days of the earthquakes, with significant variation starting 1–3 days prior to the earthquake concerned. This present study is an approach for identifying the precursory signatures of earthquakes on LF signal propagation using a new methodology with V_d parameter.     

Integration of artificial intelligence with meta classifiers for the gully erosion susceptibility assessment in Hinglo river basin,Eastern India

The main aim of this study is to evaluate the gully erosion susceptibility coupling the artificial intelligence and machine learning ensemble approaches. In the present study, the multilayer perceptron neural network (MLP) was used as the base classifier and the hybrid ensemble machine learning methods i.e. Bagging and Dagging were used as the functional classifiers. The Hinglo river basin, an important tributary of the Ajay River was selected as the study area, consists with the parts of Chhotonagpur plateau and Rarh lateritic region. The study area is facing the gully erosion problems which are interrupted the growth of the agriculture. The gully erosion susceptibility maps (GESMs), prepared by MLP, MLP-Bagging and MLP-Dagging were classified into four classes such as low, moderate, high and very high susceptibility classes with the help of natural break method (NBM) in GIS environment. The very high susceptibility class covered 19.41% (MLP), 13.52% (MLP-Bagging) and 15.30% (MLP-Dagging) areas of the basin. For the evaluation and comparison of the models, receiver operating characteristics (ROC), accuracy, mean absolute error (MAE) and root mean square error (RMSE) were applied. Overall, all the gully erosion susceptibility models were performed as excellent. Integration of hybrid ensemble models with MLP has increase the accuracy of the MLP models. Among these models MLP-Dagging has achieved the highest accuracy in compare to the other models. The importance of the selected factors in the present study was assessed by the Relief-F method. The results show that the soil type factor has the highest predictive performance. Sensitivity analysis also showed soil type as most important factor. The gully erosion susceptibility maps (GESMs) are considered as the efficient tool which could be used to take the necessary steps for mitigating and controlling the soil erosion problem and sustainable environmental management and development.     

The origin of the smaller, faster, cheaper approach in NASA’s solar system exploration program

The current emphasis on smaller, faster, cheaper (SFC) spacecraft in NASA’s solar system exploration program is the product of a number of interacting – even interdependent – factors. The SFC concept as applied to NASA’s solar system exploration program can be viewed as the vector sum of (1) the space science community’s desire for more frequent planetary missions to plug the data gaps, educate the next generation of scientists, provide missions to targets of opportunity, and enable programmatic flexibility in times of budgetary crisis; (2) the poor publicity garnered by NASA in the early 1990s and the resultant atmosphere of public criticism (creating an opportunity for reform); (3) The Strategic Defense Initiative Organization’s and the National Space Council community’s desire to advance the Space Exploration Initiative and their perception that the NASA culture at the time represented a barrier to the effective pursuit of space exploration; (4) the effective leadership of NASA Administrator Daniel Goldin; and (5) the diminishing budget profile for space sciences in the early 1990s. This paper provides a summary of the origin of the smaller, faster, cheaper approach in the planetary program. A more through understanding of the history behind this policy will enable analysts to assess more accurately the relative successes and failures of NASA’s new approach to solar system exploration.     

Excitation of electrostatic plasma waves by a moving charged source in a quantum plasma

Within a quantum hydrodynamic model and using the reductive perturbation technique, the nonlinear ion-acoustic wave (IAW) excitations due to a moving charged object in an electron-pair-ion quantum plasma are studied both analytically and numerically. In such quantum plasmas we have derived forced Korteweg-de Vries (fKdV) type equation for finite amplitude nonlinear IAWs. The effect of relevant plasma parameters on solitonic excitations is investigated. Numerical simulation shows the generation of advancing solitons ahead of the forcing term traveling at a faster rate with trailing wakes behind the forcing disturbance. It is found that propagation characteristics of nonlinear excitations are significantly affected by quantum parameter. Additionally, we have pursued our analysis by extending it to account for arbitrary amplitude IA solitons, and derived a system of nonlinear differential equations which are analyzed numerically to study the dynamics. Nonlinear analysis predicts the existence of periodic and quasiperiodic nature of the nonlinear system and reveals that the transition from quasiperiodic to periodic behavior occurs due to the variation of quantum diffraction.     

The integrated applications promotion: A new field of action for the European Space Agency

Since ESA's establishment the context in which it operates has evolved greatly, from one of development of technologies and general competence to one of responding to the needs of an increasingly wide range of users, many of whose requirements straddle several applications categories. The IAP programme is ESA's response to this challenge, aimed at fostering the growth of a downstream industry, creating a market for the space industry and serving economic growth overall. The programme's structure and the platforms themselves are described and the programme's achievements and prospects presented. Its success testifies to ESA's continuing ability to adapt to changing environments and operate effectively in new sectors.     

Analysis of Surface Micro Machined RF MEMS Phase Shifters

Development of low loss radio frequency micro-electro-mechanical (MEMS) phase shifters for radar and telecommunication applications is presented. Numerical simulation results using electromagnetic simulator tools (CST - Germany) along with fabricated wafer level measurement results of two distributed MEMS phase shifters are presented herein for upstate capacitive bridge position. The distributed MEMS phase shifter consists of coplanar waveguide (CPW) transmission line and several MEMS bridges loading capacitively on transmission lines to create a slow wave structure. Two configurations of phase shifters are presented. 1) Conventional distributed MEMS transmission line (DMTL) 2) coplanar waveguide - microstrip - coplanar waveguide (CPW-MS-CPW), with microstrip as the transmission line and CPW as input and output line. The electromagnetic simulation results of gap height variation to change the phase velocity and, in turn, phase shift is presented. Work is underway to vary the gap height between transmission line and the bridge, applying the actuation voltage to bridge capacitors, which, in turn, will vary the bridge capacitance, changing the phase velocity on fabricated phase shifters. The match between simulated results and wafer level measurements are encouraging and will be presented in the full paper. Work is also underway to validate wafer level measurements along with numerical simulation using circuit models using circuit simulator. The custom model libraries for phase shifters are being developed. The results are encouraging.     

Comparison of ground reflectance measurement with satellite derived atmospherically corrected reflectance: A case study over semi-arid landscape

Atmospheric corrections to satellite data are important for comparing multitemporal data sets over tropical regions with variable aerosol loading. In this study, we evaluated the potential of 6S radiative transfer model for atmospheric corrections of IRS-P6 AWiFS satellite data sets, in a semi-arid landscape. Ground measurements of surface reflectance representing different land use/land cover categories were conducted to relate IRS-P6 AWiFS top of atmospheric reflectance. The 6S radiative transfer model was calibrated for local conditions using ground measurements for aerosol optical depth, water vapor and ozone with a sun photometer. Surface reflectance retrieved from 6S code was compared with top of atmosphere (TOA) reflectance and ground based spectroradiometer measurements. Accurate parameterization of the 6S model using measurements of aerosol optical depth, water vapor and ozone plays an important role while comparing ground and satellite derived reflectance measurements.     

Correlation analysis of combined and separated effects of wing deformation and support system in the CAE-AVM study

The Chinese Aeronautical Establishment (CAE) Aerodynamic Validation Model (AVM) is a dual-purpose test geometry dedicated to verify the aerodynamic performance of a conceptual intercontinental jet aircraft and to provide a dataset for CFD software validation. To this end, a scaled model of the AVM was tested in the High-Speed Tunnel (HST) of the German-Dutch Wind-tunnels (DNW) with special test consideration and instrumentation. For complementary analysis of experimental results, specific CAE-AVM geometries are analyzed using a CAE in-house CFD code. The specific geometries consist of a baseline aircraft, an aircraft with a deformed wing shape, and an aircraft with both a deformed wing shape and a representation of the model support system used in the wind tunnel. Detailed analysis of numerical and experimental results is presented; both the combined and individual attributions of wing deformation and support system interference on wing pressure distributions and longitudinal aerodynamic characteristics are summarized.