13,629 research outputs found

    A specialized inventory problem in banks: optimizing retail sweeps

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    Deposits held at Federal Reserve Banks are an essential input to the business activity of most depository institutions in the United States. Managing these deposits is an important and complex inventory problem, for two reasons. First, Federal Reserve regulations require that depository institutions hold certain amounts of such deposits at the Federal Reserve Banks to satisfy statutory reserve requirements against customers* transaction accounts (demand deposits and other checkable deposits). Second, some inventory of such deposits is essential for banks to operate one of their core lines of business: furnishing payment services to households and firms. including wire transfers, ACH payments, and check clearing settlement. Because the Federal Reserve does not pay interest on such deposits used to satisfy statutory reserve requirements, banks seek to minimize their inventory of such deposits. In 1994, the banking industry introduced a new inventory management tool for such deposits, the retail deposit sweep program, which avoids the statutory requirement by reclassifying transaction deposits as savings deposits. In this analysis, we examine two algorithms for operating such sweeps programs within the limits of Federal Reserve regulations.Banks and banking ; Retail trade

    Fission-fusion dynamics and group-size dependent composition in heterogeneous populations

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    Many animal groups are heterogeneous and may even consist of individuals of different species, called mixed-species flocks. Mathematical and computational models of collective animal movement behaviour, however, typically assume that groups and populations consist of identical individuals. In this paper, using the mathematical framework of the coagulation-fragmentation process, we develop and analyse a model of merge and split group dynamics, also called fission-fusion dynamics, for heterogeneous populations that contain two types (or species) of individuals. We assume that more heterogeneous groups experience higher split rates than homogeneous groups, forming two daughter groups whose compositions are drawn uniformly from all possible partitions. We analytically derive a master equation for group size and compositions and find mean-field steady-state solutions. We predict that there is a critical group size below which groups are more likely to be homogeneous and contain the abundant type/species. Despite the propensity of heterogeneous groups to split at higher rates, we find that groups are more likely to be heterogeneous but only above the critical group size. Monte-Carlo simulation of the model show excellent agreement with these analytical model results. Thus, our model makes a testable prediction that composition of flocks are group-size dependent and do not merely reflect the population level heterogeneity. We discuss the implications of our results to empirical studies on flocking systems.Comment: 19 pages, 8 figure

    Ion beam induced enhanced diffusion from gold thin films in silicon

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    Enhanced diffusion of gold atoms into silicon substrate has been studied in Au thin films of various thicknesses (2.0, 5.3, 10.9 and 27.5 nm) deposited on Si(111) and followed by irradiation with 1.5 MeV Au2+ at a flux of 6.3x10^12 ions cm-2 s-1 and fluence up to 1x10^15 ions cm-2. The high resolution transmission electron microscopy measurements showed the presence of gold silicide formation for the above-mentioned systems at fluence greater than equal to 1x1014 ions cm-2. The maximum depth to which the gold atoms have been diffused at a fluence of 1x10^14 ions cm-2 for the cases of 2.0, 5.3, 10.9 and 27.5 nm thick films has been found to be 60, 95, 160 and 13 nm respectively. Interestingly, at higher fluence of 1x1015 ions cm-2 in case of 27.5 nm thick film, gold atoms from the film transported to a maximum depth of 265 nm in the substrate. The substrate silicon is found to be amorphous at the above fluence values where unusually large mass transport occurred. Enhanced diffusion has been explained on the basis of ion beam induced, flux dependent amorphous nature of the substrate, and transient beam induced temperature effects. This work confirms the absence of confinement effects that arise from spatially confined structures and existence of thermal and chemical reactions during ion irradiation.Comment: 15 pages, 3 figure

    Comparison between Windowed FFT and Hilbert-Huang Transform for Analyzing Time Series with Poissonian Fluctuations: A Case Study

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    Hilbert-Huang Transform (HHT) is a novel data analysis technique for nonlinear and non-stationary data. We present a time-frequency analysis of both simulated light curves and an X-ray burst from the X-ray burster 4U 1702-429 with both the HHT and the Windowed Fast Fourier Transform (WFFT) methods. Our results show that the HHT method has failed in all cases for light curves with Poissonian fluctuations which are typical for all photon counting instruments used in astronomy, whereas the WFFT method can sensitively detect the periodic signals in the presence of Poissonian fluctuations; the only drawback of the WFFT method is that it cannot detect sharp frequency variations accurately.Comment: 10 pages, 12 figure

    Fabrication and performance evaluation of vertical farming structures

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    This study was undertaken to fabricate Vertical Farming Structures (VFS) suitable for homestead and evaluate the performance of fabricated vertical farming structures. The experiment was conducted in Kelappaji College of Agricultural Engineering and Technology (KCAET), Tavanur, in Malappuram district, Kerala. Two vertical farming structures DVFS 1 (Developed vertical farming structure 1) and DVFS 2 (Developed vertical farming structure 2) were designed and fabricated. The drip irrigation system was adopted to irrigate the plants to reduce the wastage of water. Amaranthus seedlings of variety ‘Kannara local’ was taken for the trial. Climatic parameters and biometric observations were analyzed to compare and evaluate the performances of vertical farming structures. Correlation analysis was done using IBM SPSS statistics 25 software. The analysis of trials revealed that DVFS 1 showed better performance in every aspect compared to DVFS 2. The biometric observations like plant height and number of leaves were more in T1 at the right side and followed by T3 at the right side of DVFS 1. The plant characteristics are highly correlated with the light intensity. This was the reason for more growth was observed on the right side of DVFS 1. The maximum yield was obtained from the DVFS 1 (58%) than DVFS 2 (42%).  The study recommended that usage of the platform like structure with triangular cross-section was more advantageous than the structure with tiers one over the other with Poly Vinyl Chloride (PVC) splits

    മത്സ്യപോഷണവും തീററയുല്പാദനവും (Fish nutrition and feed production)

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    Man began to think of fish culture when he realised that the oceans and other waterbodies could not provide sufficient fish to meet the demand of increasing population. This led to the beginning of studies on the reproduction and nutritional requirements of different species of fish. Fish that grow in natural waters get their food from their environment. They move in the sea, lake or river in search of food and favourable conditions for growth and reproduction. When fish are stocked in ponds and farms they have to get additional supply of nutrients fi*om external sources

    Biexciton recombination rates in self-assembled quantum dots

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    The radiative recombination rates of interacting electron-hole pairs in a quantum dot are strongly affected by quantum correlations among electrons and holes in the dot. Recent measurements of the biexciton recombination rate in single self-assembled quantum dots have found values spanning from two times the single exciton recombination rate to values well below the exciton decay rate. In this paper, a Feynman path-integral formulation is developed to calculate recombination rates including thermal and many-body effects. Using real-space Monte Carlo integration, the path-integral expressions for realistic three-dimensional models of InGaAs/GaAs, CdSe/ZnSe, and InP/InGaP dots are evaluated, including anisotropic effective masses. Depending on size, radiative rates of typical dots lie in the regime between strong and intermediate confinement. The results compare favorably to recent experiments and calculations on related dot systems. Configuration interaction calculations using uncorrelated basis sets are found to be severely limited in calculating decay rates.Comment: 11 pages, 4 figure
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