Secure Satellite Communication Systems Design with Individual Secrecy Rate Constraints

In this paper, we study multibeam satellite secure communication through physical (PHY) layer security techniques, i.e., joint power control and beamforming. By first assuming that the Channel State Information (CSI) is available and the beamforming weights are fixed, a novel secure satellite system design is investigated to minimize the transmit power with individual secrecy rate constraints. An iterative algorithm is proposed to obtain an optimized power allocation strategy. Moreover, sub-optimal beamforming weights are obtained by completely eliminating the co-channel interference and nulling the eavesdroppers' signal simultaneously. In order to obtain jointly optimized power allocation and beamforming strategy in some practical cases, e.g., with certain estimation errors of the CSI, we further evaluate the impact of the eavesdropper's CSI on the secure multibeam satellite system design. The convergence of the iterative algorithm is proven under justifiable assumptions. The performance is evaluated by taking into account the impact of the number of antenna elements, number of beams, individual secrecy rate requirement, and CSI. The proposed novel secure multibeam satellite system design can achieve optimized power allocation to ensure the minimum individual secrecy rate requirement. The results show that the joint beamforming scheme is more favorable than fixed beamforming scheme, especially in the cases of a larger number of satellite antenna elements and higher secrecy rate requirement. Finally, we compare the results under the current satellite air-interface in DVB-S2 and the results under Gaussian inputs.Comment: 34 pages, 10 figures, 1 table, submitted to "Transactions on Information Forensics and Security

Hartree-Fock-Bogoliubov Theory of Dipolar Fermi Gases

We construct a fully self-consistent Hartree-Fock-Bogoliubov theory that describes a spinless Fermi gas with long-range interaction. We apply this theory to a system of uniform dipolar fermionic polar molecules, which has attracted much attention recently, due to rapid experimental progress in achieving such systems. By calculating the anisotropic superfluid order parameter, and the critical temperature $T_{c}$, we show that, "hign $T_c$" superfluid can be achieved with a quite modest value of interaction strength for polar molecules. In addition, we also show that the presence of the Fock exchange interaction enhances superfluid pairing.Comment: 4.1 pages, 4 figure

Demand Forecasting for Alcoholic Beverage Distribution

Forecasting demand is one of the biggest challenges in any business, and the ability to make such predictions is an invaluable resource to a company. While difficult, predicting demand for products should be increasingly accessible due to the volume of data collected in businesses and the continuing advancements of machine learning models. This paper presents forecasting models for two vodka products for an alcoholic beverage distributing company located in the United States with the purpose of improving the company’s ability to forecast demand for those products. The results contain exploratory data analysis to determine the most important variables impacting demand, which are time of year and customer. For each of the two products, models were built to predict demand for three major customers. For each product/customer combination, this paper compares time series and deep learning models to a naive model to see if the prediction accuracy can be improved. For five out of six products, the time series models reduced error by 2.5–66.7% compared to the naive models. Also, for one product, a hybrid CNN model developed for this paper outperformed the time series models by 3–10% and reduced error by 49% compared to the naive models

Matter-wave bistability in coupled atom-molecule quantum gases

We study the matter-wave bistability in coupled atom-molecule quantum gases, in which heteronuclear molecules are created via an interspecies Feshbach resonance involving either two-species Bose or two-species Fermi atoms at zero temperature. We show that the resonant two-channel Bose model is equivalent to the nondegenerate parametric down-conversion in quantum optics, while the corresponding Fermi model can be mapped to a quantum optics model that describes a single-mode laser field interacting with an ensemble of inhomogeneously broadened two-level atoms. Using these analogy and the fact that both models are subject to the Kerr nonlinearity due to the two-body s-wave collisions, we show that under proper conditions, the population in the molecular state in both models can be made to change with the Feshbach detuning in a bistable fashion.Comment: 6 pages, 5 figure

Estructura y propiedades térmicas de oleogeles a base de cera de abejas con diferentes tipos de aceites vegetales

Beeswax-based oleogels with different types of vegetable oil, including camellia oil (CO), soybean oil (SO), sunflower oil (SFO), or flaxseed oil (FO), were prepared and their structure and thermal properties were evaluated. The critical concentration of oleogel obtained from each of CO, SO, and SFO at 25 °C was 3% (w/w), and that from FO was 4%. Thermal measurements revealed similar thermodynamic curves for oleogels in different lipid phases. X-Ray diffraction showed orthorhombic perpendicular subcell packing and characteristic peaks of the β’ form. Furthermore, a morphology analysis of the crystals showed that they were needle shaped. Fourier transform-infrared spectra revealed that beeswax-based oleogels were formed via non-covalent bonds and may be stabilized with physical entanglements. The oleogels showed oil type-dependent oxidative abilities, but they were all stable and showed no obvious changes in peroxide value during 90 days of storage at 5 °C.Se prepararon oleogeles a base de cera de abejas con diferentes tipos de aceite vegetal, incluido el aceite de camelia (CO), de soja (SO), girasol (SFO) y linaza (FO), y se evaluaron la estructura y las propiedades térmicas. La concentración crítica de oleogel obtenida de cada uno de los aceites de CO, SO y SFO a 25 °C fue del 3% (p / p), y la del FO fue del 4%. Las medidas térmicas dieron curvas termodinámicas similares para los oleogeles en diferentes fases lipídicas. La difracción de rayos X mostró un empaquetamiento subcelular perpendicular ortorrómbico y picos característicos de la forma β’. Además, el análisis de la morfología de los cristales mostró que tenían forma de aguja. Los espectros infrarrojos de transformada de Fourier revelaron que los oleogeles basados en cera de abejas se formaron a través de enlaces no covalentes y pueden estabilizarse con enlaces físicos. Los oleogeles mostraron capacidades oxidativas dependientes del tipo de aceite, pero todos eran estables y no tuvieron cambios obvios en el valor del peróxido durante 90 días de almacenamiento a 5 °C

Enhanced Directional Coupling of Light with a Whispering Gallery Microcavity

Directional coupling of light in nanophotonic circuits has recently attracted increasing interest, with numerous experimental realizations based on broken rotational or mirror symmetries of the light–matter system. The most prominent underlying effect is the spin–orbit interaction of light in subwavelength structures. Unfortunately, coupling of light to such structures is, in general, very inefficient. In this work, we experimentally demonstrate an order of magnitude enhancement of the directional coupling between two nanowaveguides by means of a whispering gallery microcavity. We also show that both transverse magnetic and transverse electric modes can be used for the enhancement