32,523 research outputs found

    Global and Feature Based Gender Classification of Faces: A Comparison of Human Performance and Computational Models

    Get PDF
    Original paper can be found at: http://eproceedings.worldscinet.com/9789812701886/9789812701886_0036.html Copyright World Scientific Publishing Company. http://dx.doi.org/10.1142/9789812701886_0036Most computational models for gender classification use global information (the full face image) giving equal weight to the whole face area irrespective of the importance of the internal features. Here, we use a global and feature based representation of face images that includes both global and featural information. We use dimensionality reduction techniques and a support vector machine classifier and show that this method performs better than either global or feature based representations alone.Peer reviewe

    High Performance Associative Memories and Structured Weight Dilution

    Get PDF
    Copyright SpringerThe consequences of two techniques for symmetrically diluting the weights of the standard Hopfield architecture associative memory model, trained using a non-Hebbian learning rule, are examined. This paper reports experimental investigations into the effect of dilution on factors such as: pattern stability and attractor performance. It is concluded that these networks maintain a reasonable level of performance at fairly high dilution rates

    A neural network model of visual object recognition impairment after brain damage

    Get PDF
    Dysfunction of the visual object recognition system in humans is briefly discussed and a basic connectionist model of visual object recognition is introduced. Experimentation in which two variants of this model are lesioned is undertaken. The results suggest that the well documented phenomenon of superordinate preservation is model independent. Differential category specific recognition deficits are also observed in this model, however these are sensitive to each particular variant

    Online Mobile Phone Recharge System in Nigeria

    Get PDF
    An e-portal system that allows mobile phone users to recharge their phones online without necessary purchasing any recharge card is proposed. With this e-portal system, users simply provide the amount to be loaded on the specified phone number and some series of validation are performed before finally recharging the phone with the specified amount. This e-portal system also eliminates the burden of generating random numbers as recharge cards and the subsequent huge database accompanied with the storage of these randomly generated numbers. Mobile service providers are still faced with the challenges of inefficient bandwidth utilization and congestion in the transmission channel. One of the main reasons for this congestion is the toll placed on the network by the need to reload/recharge phone credits in order to enable calls. The solution proposed in this paper is meant to improve bandwidth utilization by taking the process of recharging off the mobile clients

    Charge separation instability in an unmagnetized disk plasma around a Kerr black hole

    Full text link
    In almost all of plasma theories for astrophysical objects, we have assumed the charge quasi-neutrality of unmagnetized plasmas in global scales. This assumption has been justified because if there is a charged plasma, it induces electric field which attracts the opposite charge, and this opposite charge reduces the charge separation. Here, we report a newly discovered instability which causes a charge separation in a rotating plasma inside of an innermost stable circular orbit (ISCO) around a black hole. The growth rate of the instability is smaller than that of the disk instability even in the unstable disk region and is forbidden in the stable disk region outside of the ISCO. However, this growth rate becomes comparable to that of the disk instability when the plasma density is much lower than a critical density inside of the ISCO. In such case, the charge separation instability would become apparent and cause the charged accretion into the black hole, thus charge the hole up.Comment: 15pages, 1 figur

    The influence of the Alfv\'enic drift on the shape of cosmic ray spectra in SNRs

    Full text link
    Cosmic ray acceleration in SNRs in the presence of the Alfv\'enic drift is considered. It is shown that spectra of accelerated particles may be considerably softer in the presence of amplified magnetic fields.Comment: 4 pages, 4 figures, poster talk at 4-th Gamma-ray Symposium (Heidelberg, Germany, 7-11th of July 2008

    Joint evolution of multiple social traits: a kin selection analysis

    Get PDF
    General models of the evolution of cooperation, altruism and other social behaviours have focused almost entirely on single traits, whereas it is clear that social traits commonly interact. We develop a general kin-selection framework for the evolution of social behaviours in multiple dimensions. We show that whenever there are interactions among social traits new behaviours can emerge that are not predicted by one-dimensional analyses. For example, a prohibitively costly cooperative trait can ultimately be favoured owing to initial evolution in other (cheaper) social traits that in turn change the cost-benefit ratio of the original trait. To understand these behaviours, we use a two-dimensional stability criterion that can be viewed as an extension of Hamilton's rule. Our principal example is the social dilemma posed by, first, the construction and, second, the exploitation of a shared public good. We find that, contrary to the separate one-dimensional analyses, evolutionary feedback between the two traits can cause an increase in the equilibrium level of selfish exploitation with increasing relatedness, while both social (production plus exploitation) and asocial (neither) strategies can be locally stable. Our results demonstrate the importance of emergent stability properties of multidimensional social dilemmas, as one-dimensional stability in all component dimensions can conceal multidimensional instability

    Quantum transport at the Dirac point: Mapping out the minimum conductivity from pristine to disordered graphene

    Get PDF
    The phase space for graphene's minimum conductivity σmin\sigma_\mathrm{min} is mapped out using Landauer theory modified for scattering using Fermi's Golden Rule, as well as the Non-Equilibrium Green's Function (NEGF) simulation with a Monte Carlo sampling over impurity distributions. The resulting `fan diagram' spans the range from ballistic to diffusive over varying aspect ratios (W/LW/L), and bears several surprises. {The device aspect ratio determines how much tunneling (between contacts) is allowed and becomes the dominant factor for the evolution of σmin\sigma_{min} from ballistic to diffusive regime. We find an increasing (for W/L>1W/L>1) or decreasing (W/L<1W/L<1) trend in σmin\sigma_{min} vs. impurity density, all converging around 128q2/π3h4q2/h128q^2/\pi^3h\sim 4q^2/h at the dirty limit}. In the diffusive limit, the {conductivity} quasi-saturates due to the precise cancellation between the increase in conducting modes from charge puddles vs the reduction in average transmission from scattering at the Dirac Point. In the clean ballistic limit, the calculated conductivity of the lowest mode shows a surprising absence of Fabry-P\'{e}rot oscillations, unlike other materials including bilayer graphene. We argue that the lack of oscillations even at low temperature is a signature of Klein tunneling
    corecore