Cross Calibration and Validation of Landsat 8 OLI and Sentinel 2A MSI

This work describes a proposed radiometric cross calibration between the Landsat 8 Operational Land Imager (OLI) and Sentinel 2A Multispectral Instrument (MSI) sensors. The cross calibration procedure involves i) correction of the MSI data to account for spectral band differences with the OLI; and ii) correction of BRDF effects in the data from both sensors using a new model accounting for the view zenith/azimuth angles in addition to the solar zenith/view angles. Following application of the spectral and BRDF corrections, standard least-squares linear regression is used to determine the cross calibration gain and offset in each band. Uncertainties related to each step in the proposed process are determined, as is the overall uncertainty associated with the complete processing sequence. Validation of the proposed cross calibration gains and offsets is performed on image data acquired over the Algodones Dunes site. In general, the estimated cross calibration offsets in all bands were small, on the order of 0.0075 or less in magnitude. The cross calibration gains generally varied less than 1.0% from unity; for the Blue and Red bands, the gains varied by approximately -2.5% and - 1.4% from unity, respectively. For a forced zero offset, the estimated gain in all but the Blue band changed little; the Blue band gain varied by approximately 1.86% from unity. Consequently, cross calibration of the Blue band requires both the gain and nonzero offset. To maintain processing consistency, it is recommended to use the gain and (nonzero) offset in all bands. Overall, the net uncertainty in the proposed process was estimated to be on the order of 6.76%, with the largest uncertainty component due to each sensor’s calibration uncertainty, on the order of 5% and 3% for the MSI and OLI, respectively. Other significant contributions to the uncertainty include: seasonal changes in solar zenith and azimuth angles, on the order of 2.27%; target site non-uniformity, on the order of 1.8%; variability in atmospheric water vapor and/or aerosol concentration, on the order of 1.29%; and potential shifts in each sensor’s spectral filter central wavelength and/or bandwidth, on the order of 0.82% and 0.28%, respectively

Numerical fault simulation in Himalayas with 2 D finite element method

The nature of the stress field in the Himalaya is examined by the 2D finite element method where linear elastic rheology and plain strain condition are assumed. The Mohr-Coulomb failure criterion has been adopted to analyze the relationship between stress distribution and fault formation.Two profile models are prepared and convergent displacement is imposed on them along the NE-SW horizontal direction.The convergent displacement and physical properties of the rock layer control the distribution,orientation,magnitude and intensity of the stress and fault development.According to the calculated stress pattern,thrust faults are expected to develop in the central Himalaya (model A).Normal and some thrust faults take place in the north-western Himalaya (model B).The results from our numerical experiment are in agreement with those from the seismicity and focal mechanism solution of earthquakes and also with those of M.M.Alam and D.Hayashi (Bull.Fac.Sci.Univ. Ryukyus, 73, 15, 2002) in the central Himalaya

MEASUREMENT OF RIDER INDUCED LOADS DURING SIMULATED BICYCLING

Research related to bicycling has broadened in scope over the last decade. Prior to about 1975, the majority of bicycling related research was dedicated to topics surrounding the physiology of human performance. These early efforts served to stimulate interest in bicycling research with the result that more recent research has explored a diversity of topics ranging from fundamentals of muscle mechanics to measurement of foot/pedal loads. Despite the both broadened and intensified research activity, one topic, which has recei ved no attention to the authors I knowledge, is measurement of the complete loading induced by the rider on the bicycle frame. The importance of this topic lies in the applicability of the results to two areas, design analysis of bicycle components including the frame and biomechanical analysis of the pedalling process. The concern in the present article is with the biomechanical analysis

An Experimental and Numerical Comparison of Flow Hydraulic Parameters in Circular Crested Weir Using Flow3D

Circular crested weirs consist of a circular crested of upstream and downstream walls. These weirs are widely used in hydraulic engineering as water discharge structures and can be used to control water level in channels and tanks. In the present study, using Flow3D software, hydraulic properties were investigated to find weir geometry optimization through CFD method. Also, this study attempted to investigate flow on some sections of circular crested weirs in 3 groups and 11 models. Upstream and downstream slope changes as well as the height of the weir were also studied. To validate the model, laboratory models were used. In the research, flow depth parameters on crest, pressure distribution, velocity distribution, energy loss on circular crested weirs, as well as the height and changes of upstream and downstream slope were evaluated. Flow depth on the body of circular crest in this state is about 0.71 (H1). Upstream slope changes on flow depth on the weir’s crest revealed that increasing upstream slope causes to the increase of flow relative depth (H1/R) on the crest about 62%. Downstream changes in H1/R values less than 0.7 have no significant effect on discharge coefficient; however, increasing H1/R values seems to cause more change in slope

Effectiveness of Rich Document Representation in XML Retrieval

Information Retrieval (IR) systems are built with different goals in mind. Some IR systems target high precision that is to have more relevant documents on the first page of their results. Other systems may target high recall that is finding as many references as possible. In this paper we present a method of document representation called RDR to build XML retrieval engines with high specificity; that is finding more relevant documents that are mostly about the query topic. The Rich Document Representation (RDR) is a method of representing the content of a document with logical terms and statements. The conjecture is that since RDR is a better representation of the document content it will produce higher precision. On our implementation, we used the Vector Space model to compute the similarity between the XML elements and queries. Our experiments are conducted on INEX 2004 test collection. The results indicate that the use of richer features such as logical terms or statements for XML retrieval tends to produce more focused retrieval. Therefore it is a suitable document representation when users need only a few more specific references and are more interested in precision than recall