9,126 research outputs found

    The Use of AIS Data for Identifying and Mapping Calcareous Soils in Western Nebraska

    Get PDF
    The identification of calcareous soils, through unique spectral responses of the vegetation to the chemical nature of calcareous soils, can improve the accuracy of delineating the boundaries of soil mapping units over conventional field techniques. The objective of this experiment is to evaluate the use of the Airborne Imaging Spectrometer (AIS) in the identification and delineation of calcareous soils in the western Sandhills of Nebraska. Based upon statistical differences found in separating the spectral curves below 1.3 microns, calcareous and non-calcareous soils may be identified by differences in species of vegetation. Additional work is needed to identify biogeochemical differences between the two soils

    The quiescent progenitors of four Type II-P/L supernovae

    Get PDF
    We present Large Binocular Telescope difference imaging data for the final years of four Type II-P/L supernovae progenitors. For all four, we find no significant evidence for stochastic or steady variability in the U, B, V, or R-bands. Our limits constrain variability to no more than roughly 5-10% of the expected R-band luminosities of the progenitors. These limits are comparable to the observed variability of red supergiants in the Magellanic Clouds. Based on these four events, the probability of a Type II-P/L progenitor having an extended outburst after Oxygen ignition is <37% at 90% confidence. Our observations cannot exclude short outbursts in which the progenitor returns to within ~10% of its quiescent flux on the time scale of months with no dust formation.Comment: 9 pages, 8 figures, 1 table. Accepted to MNRA

    Cross-layer distributed power control: A repeated games formulation to improve the sum energy-efficiency

    Get PDF
    The main objective of this work is to improve the energy-efficiency (EE) of a multiple access channel (MAC) system, through power control, in a distributed manner. In contrast with many existing works on energy-efficient power control, which ignore the possible presence of a queue at the transmitter, we consider a new generalized cross-layer EE metric. This approach is relevant when the transmitters have a non-zero energy cost even when the radiated power is zero and takes into account the presence of a finite packet buffer and packet arrival at the transmitter. As the Nash equilibrium (NE) is an energy-inefficient solution, the present work aims at overcoming this deficit by improving the global energy-efficiency. Indeed, as the considered system has multiple agencies each with their own interest, the performance metric reflecting the individual interest of each decision maker is the global energy-efficiency defined then as the sum over individual energy-efficiencies. Repeated games (RG) are investigated through the study of two dynamic games (finite RG and discounted RG), whose equilibrium is defined when introducing a new operating point (OP), Pareto-dominating the NE and relying only on individual channel state information (CSI). Accordingly, closed-form expressions of the minimum number of stages of the game for finite RG (FRG) and the maximum discount factor of the discounted RG (DRG) were established. The cross-layer model in the RG formulation leads to achieving a shorter minimum number of stages in the FRG even for higher number of users. In addition, the social welfare (sum of utilities) in the DRG decreases slightly with the cross-layer model when the number of users increases while it is reduced considerably with the Goodman model. Finally, we show that in real systems with random packet arrivals, the cross-layer power control algorithm outperforms the Goodman algorithm.Comment: 36 pages, single column draft forma

    Cross-Layer Design for Green Power Control

    Full text link
    In this work, we propose a new energy efficiency metric which allows one to optimize the performance of a wireless system through a novel power control mechanism. The proposed metric possesses two important features. First, it considers the whole power of the terminal and not just the radiated power. Second, it can account for the limited buffer memory of transmitters which store arriving packets as a queue and transmit them with a success rate that is determined by the transmit power and channel conditions. Remarkably, this metric is shown to have attractive properties such as quasi-concavity with respect to the transmit power and a unique maximum, allowing to derive an optimal power control scheme. Based on analytical and numerical results, the influence of the packet arrival rate, the size of the queue, and the constraints in terms of quality of service are studied. Simulations show that the proposed cross-layer approach of power control may lead to significant gains in terms of transmit power compared to a physical layer approach of green communications.Comment: Presented in ICC 201

    Pseudogap in high-temperature superconductors from realistic Fr\"ohlich and Coulomb interactions

    Get PDF
    It has been recently shown that the competition between unscreened Coulomb and Fr\"{o}hlich electron-phonon interactions can be described in terms of a short-range spin exchange JpJ_p and an effective on-site interaction U~\tilde{U} in the framework of the polaronic tt-JpJ_p-U~\tilde{U} model. This model, that provides an explanation for high temperature superconductivity in terms of Bose-Einstein condensation (BEC) of small and light bipolarons, is now studied as a charged Bose-Fermi mixture. Within this approximation, we show that a gap between bipolaron and unpaired polaron bands results in a strong suppression of low-temperature spin susceptibility, specific heat and tunneling conductance, signaling the presence of normal state pseudogap without any assumptions on preexisting orders or broken symmetries in the normal state of the model.Comment: 5 pages, 5 figure

    Sistem Informasi Rental Di Venus Rental YOGYAKARTA

    Full text link
    Cd Rental is a service business related to the entertainment world, as a promising business rentals cd then it should use a system / program in every transaction. Rental Venus CD (VCD and DVD rental) is one of the rental with a number of CDs and a lot of customers. Data from each CD are written into a book that certainly requires a lot of time and accuracy when employees need the data to customers or to the report. While experiencing a CD every month stock additions and deductions, so that should be checked periodically if there is data to be renewed. The combination of Microsoft Visual Basic 6.0 with MySQL, it is very helpful in the process of making lending transaction and return the application cd as well as searching the data, thus increasing the effectiveness of the work which had previously been an obstacle. The report generated a level of accuracy even when compared with the manual system previously use

    Microscaled and nanoscaled platinum sensors

    Get PDF
    We show small and robust platinum resistive heaters and thermometers that are defined by microlithography on silicon substrates. These devices can be used for a wide range of applications, including thermal sensor arrays, programmable thermal sources, and even incandescent light emitters. To explore the miniaturization of such devices, we have developed microscaled and nanoscaled platinum resistor arrays with wire widths as small as 75 nm, fabricated lithographically to provide highly localized heating and accurate resistance (and hence temperature) measurements. We present some of these potential applications of microfabricated platinum resistors in sensing and spectroscopy

    Seasonal undernutrition in rural Ethiopia:

    Get PDF
    Marked seasonal variability of both production- and consumption is characteristic of virtually all farming systems in the developing world. This study examines the magnitude and significance of seasonal undernutrition in south central Ethiopia, southern Shewa and Zigwa Boto, a peasant association in the Gurage Zone. The study seeks to answer five questions: (1)Does seasonal energy stress affect individuals of various age groups and sexes differently? (2)Do members of the same household show divergent responses to seasonal energy stress? (3)What are the functional consequences of different levels of adult undernutrition? (4)Are the current anthropometric cut-off points for adults appropriate for rural Ethiopia? (5)What household characteristics are associated with vulnerability to seasonal undernutrition? A number of important findings emerge from this research.....The study clarifies some points of contention in the field of adult undernutrition and shows how seasonal undernutrition operates as an intermittent warning signal, reminding us not to miss opportunities to promote good nutrition throughout the life cycle.Nutrition, Ethiopia, Malnutrition., Food crops., Climate.,

    Impact of Mobility on MIMO Green Wireless Systems

    Full text link
    This paper studies the impact of mobility on the power consumption of wireless networks. With increasing mobility, we show that the network should dedicate a non negligible fraction of the useful rate to estimate the different degrees of freedom. In order to keep the rate constant, we quantify the increase of power required for several cases of interest. In the case of a point to point MIMO link, we calculate the minimum transmit power required for a target rate and outage probability as a function of the coherence time and the number of antennas. Interestingly, the results show that there is an optimal number of antennas to be used for a given coherence time and power consumption. This provides a lower bound limit on the minimum power required for maintaining a green network.Comment: Accepted for EUSIPCO conference. 5 page
    corecore