Using Fuzzy Neural Networks and Analytic Hierarchy Process for Supplier Classification in e-Procurement

Electronic procurement is frequently defined as the sourcing of goods or services via electronic means, usually through the internet. A major process in the e-procurement decision making is that of supplier selection process. In the real world, the criteria and constraints for such a process are subjective in nature. In this study, the criteria for supplier selection, which already have been established empirically, has been adopted and no new criteria for the same has been proposed. These criteria and constraints have been modeled using fuzzy logic into constraints, which further has been modeled as a multi-objective decision making process, by combining neural networks and analytic hierarchy process. Then the suppliers have been classified into suitable suppliers and unsuitable suppliers, from the viewpoint of the firm

Dark matter, extra-terrestrial gamma-rays and the MSSM: a viability study

We fit the $\gamma$-ray excess from the galactic centre (GC) in terms of parameters of the minimal supersymmetric standard model (MSSM). Consistency with other $\gamma$-ray observation, such as those from dwarf spheroidal galaxies, is also ensured, in addition to the constraints from direct dark matter search. Furthermore, we expect the contribution to the relic density from the MSSM dark mater candidate, namely, the lightest neutralino, should not go below the stipulated value; otherwise it will amount to going beyond the MSSM by including some additional dark matter source. After a detailed scan of the parameter space in terms of four representative types of particle spectra, we identify the ones that are best fit to the observed data. However, these two are somewhat unsatisfactory in terms of $\chi^2_{min}$ as well as $p$-values. In some case(s), the unacceptability of low-$\chi^2_{min}$ regions due to direct search constraint is responsible for this. In others, the observed shape of the $\gamma$-ray spectrum makes the fits unsatisfactory. The imposed lower limit on relic density, too, has a role to play all along. On the whole, the conclusion is that the MSSM is not a very satisfactory fit for the GC $\gamma$-ray compounded with other cosmological observations and direct search limits.Comment: 40 pages, 16 figures: figures corrected, typos corrected, matches with version published in JCA

Halo-independent bounds on Inelastic Dark Matter

We discuss halo-independent constraints on the Inelastic Dark Matter (IDM) scenario, in which a Weakly Interaction Massive Particle (WIMP) state $\chi$ with mass $m_\chi$ interacts with nuclear targets by upscattering to a heavier state $\chi^{\prime}$ with mass $m_\chi+\delta$. In order to do so we adopt the single-stream method, that exploits the complementarity of Direct Detection (DD) and Capture in the Sun to extend the experimental sensitivity to the full range of incoming WIMP speeds. We show that a non-vanishing mass splitting $\delta$ modifies such range, and that for particular combinations of $m_\chi$ and $\delta$ the complementarity between the two detection techniques required by the method is lost. Specifically, assuming for the escape velocity in our Galaxy $u_{esc}$ the reference value $u_{esc}^{ref}$ = 560 km/s a halo-independent bound is possible when $\delta\lesssim$ 510 keV for a Spin-Independent interaction and when $\delta\lesssim$ 245 keV for a Spin-Dependent interaction (with the Spin-Independent value slightly reduced to $\delta\lesssim$ 490 keV when $u_{esc}>u_{esc}^{ref}$). In the low-mass regime the bound from capture in the Sun is always more constraining than that for DD and is sufficient alone to provide a halo-independent constraint, while for large WIMP masses the halo-independent bound is given by a combination of capture in the Sun and DD. We also find that, for $u_{esc}$ = $u_{esc}^{ref}$, unless the mass of the target used in DD is larger than about four times that of the target driving capture in the Sun, DD does not play any role in the determination of the maximal value of $\delta$ for which a halo-independent bound is possible. We also discuss the issue of thermalization of IDM within the Sun and show that its impact on our results is mild.Comment: 32 pages and 11 figures. Discussion on thermalization added. Updated to published versio

Using Neural Networks for Pattern Association for the Online Purchase of Products

Abstract: Today, a huge percentage of all the business transactions that take place in the domain of e-commerce are dominated by online shopping after the virtual market conceptualization of the business. This paper focuses on how pattern association rules may be obtained from the dynamic databases generated during purchases in an e-Store to maximize the profit of the marketer. In this paper, ANN has been used as a tool for generating pattern association rules during online purchases of products to aid the cross-selling of products. For getting the rules, a methodology using artificial neural networks has been adapted for usage using an extended Delta rule for initial training of the network and a hetero-associative neural network for generating and storing the associative rules. Also, a methodology has been proposed to filter out all rules which do not add economic value to the firm and then select that rule which will meet the profit maximization objective of the marketer

Searching for relativistic axions in the sky

Relativistic axions produced in decays of ${\mathcal O}(10^{-7}-10^{-2}$ $\text{eV})$ dark matter (DM) partially convert to photons after traversing the galactic magnetic field, giving rise to a signal observable by the Square Kilometer Array (SKA) radio telescope. We show that for axions lighter than a few $\times$ $10^{-13}$ eV a 100\,h SKA observation of the local dwarf galaxy Seg I would probe parameter space not constrained by stellar cooling and cosmological observations, with sensitivity several orders of magnitude better than the planned dedicated axion dark matter search experiments. We quantify the uncertainties in the SKA sensitivity projections due to two effects that enhance the photon flux: the presence of turbulent magnetic fields inside the galaxy, and the Bose enhancement of the DM decays to axions, where the latter, in particular, warrants further study.Comment: 24 pages, 12 figure

Heavy dark matter particle annihilation in dwarf spheroidal galaxies: radio signals at the SKA telescope

A weakly interacting dark matter candidate is very difficult to detect at high-energy colliders like the LHC, if its mass is close to, or higher than, a TeV. We argue that the pair-annihilation of such particles may give rise to $e^+ e^-$-pairs in dwarf spheroidal galaxies (dSph), which in turn can lead to radio synchrotron signals that are detectable at the upcoming square kilometre array (SKA) telescope within a fairly moderate observation time. We investigate in detail the underlying mechanisms that make this possible. Both particle physics issues and those pertaining to astrophysics, such as diffusion, electromagnetic energy loss and the effects of interstellar magnetic field, are examined with reference to their roles in generating radio flux. We first identify the detectability criteria in a model-independent manner. It is observed that fluxes may be detectable for scenarios that are consistent with all constraints available till date from $\gamma$-ray and cosmic-ray observations. Thereafter, using benchmarks based on popular scenarios involving physics beyond the standard model, we show that it should be possible to detect the radio flux from a dSph like Draco with 100 hours of observation at the SKA, for dark matter particle masses upto 4-8 TeV. The corresponding frequency distributions are also presented, where it is found that the frequency range 300 MHz - 50 GHz is especially useful for recording the annihilation signals of trans-TeV particles.Comment: 27 pages, 14 figure