Uncertainties for Pre- and Post-Launch Radiometric Calibration of Imaging Spectrometers for Multi-Sensor Applications

An important aspect to using imaging spectrometer data is the radiometric characterization and calibration of the sensors and validation of their data products and doing so with error budgets with known traceability. The radiometric accuracy of a given sensor is important for demonstrating the expected quality of data from the sensor. Known traceability allows data from multiple sensors to be directly comparable as will become more important in the near future with the expected launches of multiple imaging spectrometers from multiple countries, agencies, and commercial entities. The current work describes the state of pre- and post-launch radiometric absolute and relative uncertainties and their role in harmonising on-orbit data. Examples of prelaunch uncertainties based on the calibration of EnMAP and the calibration planned for the CLARREO Pathfinder Mission are presented highlighting recent work in the area of detector-based approaches using tunable laser sources. Post-launch calibration approaches for Pathfinder, EnMAP, CHIME, and DESIS including traditional vicarious calibration methods and the challenges of working with commercial data are presented. The vicarious calibration discussion relies on the example of the recently-available RadCalNet data to describe typical methods and challenges that will be faced when harmonising data between imaging spectrometers as well as with multispectral sensors

Expectation adjustment in the housing market: insights from the Scottish auction system

This paper examines price expectation adjustment of house buyers and sellers to rapid changes in the housing market using data from Scotland where houses are sold through 'first-price sealed-bid' auctions. These auctions provide more information on market signals, incentives and the behaviour of market participants than private treaty sales. This paper therefore provides a theoretical framework for analysing revealed preference data generated from these auctions. We specifically focus on the analysis of the selling to asking price difference, the 'bid-premium'. The bid-premium is shown to be affected by expectations of future price movements, market duration and high bidding frequency. The bid-premium reflects consumers' expectations, adapting to market conditions more promptly than asking price setting behaviour and final sale prices. The volatile conditions of the recent housing market bubble are fully reflected in the bid-premium, whereas the asking and sale prices are much less prone to rapid movements

Performance Characteristics of Switched Reluctance Motor Drive

In this report, methods and computational techniques for predicting the static and steady state characteristics of a switched reluctance motor drive are developed and the predicted characteristics are compared with experimental results. Because of high local saturation and narrow airgap in the SR motor, accurate calculation of the static characteristics of the torque, flux linkage, inductances, and speed emf from its FE field solution is not straightforward. For the purpose of this study, a two-dimensional finite element model is developed to handle the nonlinear magnetic field inside the machine. Based on a thorough study of the potential sources of errors in the field solution and in the computational methods used in postprocessing, new guidelines are developed regarding the shape and uniformity of the mesh in the airgap and the preservation of these qualities of the mesh as the rotor is rotated. When the proposed guidelines on the mesh configuration and its rotation were used, significant improvement in the accuracy of the field distribution and in the accuracy of the predicted torque/angle characteristics as compared to the experimentally measured torque was observed. Furthermore, all three methods of torque calculation, namely global virtual work, local virtual work, and Maxwell-stress tensor methods are converging to the same results and the torque/angle characteristics are smooth. Improvement in the prediction of such static characteristics is also essential to a realistic prediction of the steady state behavior. In the study of steady state performance of the SRM drive, the converter is approximated by a controlled, square wave pulse generator. In the integration process, the coefficients of the governing differential equation, being dependent on the phase current and rotor angle, are updated using surface interpolation method on the static characteristics. The predicted steady state characteristics compare favorably with the experimental results over a wide range of torque/speed variation

Stability of Horava-Lifshitz Black Holes in the Context of AdS/CFT

The anti--de Sitter/conformal field theory (AdS/CFT) correspondence is a powerful tool that promises to provide new insights toward a full understanding of field theories under extreme conditions, including but not limited to quark-gluon plasma, Fermi liquid and superconductor. In many such applications, one typically models the field theory with asymptotically AdS black holes. These black holes are subjected to stringy effects that might render them unstable. Ho\v{r}ava-Lifshitz gravity, in which space and time undergo different transformations, has attracted attentions due to its power-counting renormalizability. In terms of AdS/CFT correspondence, Ho\v{r}ava-Lifshitz black holes might be useful to model holographic superconductors with Lifshitz scaling symmetry. It is thus interesting to study the stringy stability of Ho\v{r}ava-Lifshitz black holes in the context of AdS/CFT. We find that uncharged topological black holes in $\lambda=1$ Ho\v{r}ava-Lifshitz theory are nonperturbatively stable, unlike their counterparts in Einstein gravity, with the possible exceptions of negatively curved black holes with detailed balance parameter $\epsilon$ close to unity. Sufficiently charged flat black holes for $\epsilon$ close to unity, and sufficiently charged positively curved black holes with $\epsilon$ close to zero, are also unstable. The implication to the Ho\v{r}ava-Lifshitz holographic superconductor is discussed.Comment: 15 pages, 6 figures. Updated version accepted by Phys. Rev. D, with corrections to various misprints. References update

TARDIS: A Numerical Simulation Package for Drive Systems

TARDIS is a digital computer simulation package originally intended to simulate drive systems. Its versatility has proved to be very useful in other areas as well. It is designed to replace the functionality of analog computers so that the user who cannot afford to have one can use the program on a personal or mainframe computer. The author believes that it is one of the most efficient and accurate simulation programs of its kind at this point even though not all of its potential has been exploited to. the fullest. It can handle index 0 and 1 differential-algebraic systems with discontinuities

Harmonic Characteristics and Voltage Support for Inverters With a Weak AC Supply

In recent years, the world-wide use of high voltage direct current (HVDC) power transmission has increased sharply. Most of the recent projects involve transmitting large amounts of power from remote generations to load centers, where the short-circuit capacity at the receiving bus is often only a few times that of the rated DC power transfer — indicative of a weak AC support that is more susceptible to various operational problems, such as harmonic amplification, poor voltage regulation and adverse effects on the firing control. This report is on a two-part investigation. The first part deals with the harmonics characteristics of an inverter with weak AC support under balanced and unbalanced network conditions using the two most common firing schemes; the individual pulse control and the equidistant pulse control. The second part examines the operational behavior of the inverter with weak AC support when supplementary VAR support in the form of static VAR compensator is used. Aside from dynamic and transient behaviors, the study also looked into possible interaction between the inverter and the thyristor-controlled reactor at the harmonic level

Some Design Calculations for a 60kW, 6000 rpm, 4/6 SRM

This report contains results from a finite element study of the SR machine whose dimensions were provided by Mr Lewis Unnewehr of Sullair Corporation. The objective of the study is to determine the static and steady-state operational characteristics of a given machine design to see if it meets certain design specifications. The study made use of a two-dimension, finite element program that has been developed and described in [1-3]. The same set of references also contained information on the simulation methods and types of control used in this study. Part I of this report presents the basic input data used in this study. The iron parts, including that of the shaft, are assumed to have the magnetic characteristics of M19 steel. The current distribution in the stator coils is assumed to be uniform. Part II contains the results from the FEM calculations: included in here are static characteristics of the flux distribution at several rotor positions, and computed profiles of the flux linkages, the induced emf, and the static torque as a function of rotor position for a range of current excitation. These static characteristics are for the base case design given in Table 1 and are obtained with only one stator phase energized at a time. Part III of the report contains results from sensitivity studies to determine the effects of variations in the airgap, in the relative width of the stator to rotor poles, in the shape of rotor poles, and in the skewing of the rotor poles. Unless otherwise stated the curves and data presented in this report are for the base case dimensions given in Table 1. Sensitivity analysis on airgap length, pole shape, and pole width have been obtained by making the appropriate changes on the rotor pole, the stator dimensions remained the same as those given in Table 1. Also presented are a set of static characteristics for a machine with a smaller airgap length of 0.5 mm. Finally, Part IV of report contains steady-state operational characteristics of the stator current and shaft torque of the machine operating in the current- and angle-control modes as predicted from a steady state simulation assuming a constant input dc voltage. In the steady state simulation the electrical condition of the machine and its torque output are modeled by the appropriate flux linkage, induced emf, and developed torque profiles given in Part II. At the end of the report is a brief discussion on some of the effects that we have studied, and the conclusion that the basic design, with standard angle and current controls, appears to be capable of delivering the desired torque

Integrin α2β1 Expression Regulates Matrix Metalloproteinase-1-Dependent Bronchial Epithelial Repair in Pulmonary Tuberculosis.

Pulmonary tuberculosis (TB) is caused by inhalation of Mycobacterium tuberculosis, which damages the bronchial epithelial barrier to establish local infection. Matrix metalloproteinase-1 plays a crucial role in the immunopathology of TB, causing breakdown of type I collagen and cavitation, but this collagenase is also potentially involved in bronchial epithelial repair. We hypothesized that the extracellular matrix (ECM) modulates M. tuberculosis-driven matrix metalloproteinase-1 expression by human bronchial epithelial cells (HBECs), regulating respiratory epithelial cell migration and repair. Medium from monocytes stimulated with M. tuberculosis induced collagenase activity in bronchial epithelial cells, which was reduced by ~87% when cells were cultured on a type I collagen matrix. Matrix metalloproteinase-1 had a focal localization, which is consistent with cell migration, and overall secretion decreased by 32% on type I collagen. There were no associated changes in the specific tissue inhibitors of metalloproteinases. Decreased matrix metalloproteinase-1 secretion was due to ligand-binding to the α2β1 integrin and was dependent on the actin cytoskeleton. In lung biopsies, samples from patients with pulmonary TB, integrin α2β1 is highly expressed on the bronchial epithelium. Areas of lung with disrupted collagen matrix showed an increase in matrix metalloproteinases-1 expression compared with areas where collagen was comparable to control lung. Type I collagen matrix increased respiratory epithelial cell migration in a wound-healing assay, and this too was matrix metalloproteinase-dependent, since it was blocked by the matrix metalloproteinase inhibitor GM6001. In summary, we report a novel mechanism by which α2β1-mediated signals from the ECM modulate matrix metalloproteinase-1 secretion by HBECs, regulating their migration and epithelial repair in TB