Robust real-time 3D head pose estimation from range data

In this paper a real-time 3D pose estimation algorithm using range data is described. The system relies on a novel 3D sensor that generates a dense range image of the scene. By not relying on brightness information, the proposed system guarantees robustness under a variety of illumination conditions, and scene contents. Efficient face detection using global features and exploitation of prior knowledge along with novel feature localization and tracking techniques are described. Experimental results demonstrate accurate estimation of the six degrees of freedom of the head and robustness under occlusions, facial expressions, and head shape variability.     

Combining bagging,boosting, rotation forest and random subspace methods

Bagging, boosting, rotation forest and random subspace methods are well known re-sampling ensemble methods that generate and combine a diversity of learners using the same learning algorithm for the base-classifiers. Boosting and rotation forest algorithms are considered stronger than bagging and random subspace methods on noise-free data. However, there are strong empirical indications that bagging and random subspace methods are much more robust than boosting and rotation forest in noisy settings. For this reason, in this work we built an ensemble of bagging, boosting, rotation forest and random subspace methods ensembles with 6 sub-classifiers in each one and then a voting methodology is used for the final prediction. We performed a comparison with simple bagging, boosting, rotation forest and random subspace methods ensembles with 25 sub-classifiers, as well as other well known combining methods, on standard benchmark datasets and the proposed technique had better accuracy in most cases.     

Acquired reactive perforating collagenosis and pseudoporphyric bullous dermatosis in a hemodialysis patient

Hemodialysis patients present with a broad spectrum of specific and nonspecific skin disorders, which rarely coexist. We report an exceptional case of a hemodialysis patient that developed acquired reactive perforating collagenosis and pseudoporphyric bullous dermatosis on the basis of common skin disorders which include hyperpigmentation, pruritus, xerosis cutis, and Linsday's nails. Interestingly, our patient presented with two unusual but distinctive cutaneous dermopathies on the background of other commonly seen skin alterations. The patient was successfully treated with allopurinol and N‐acetylcysteine. Avoidance of potentially triggering factors such as alcohol, sunlight exposure and certain medication was recommended. Thus, increasing clinical awareness, assiduous investigation and early treatment of skin disorders are required to improve the prognosis and quality of life in this patient population.     

Morphology of Oxide Particles Made by the Emulsion Combustion Method

Various oxide powders were prepared by the emulsion combustion method (ECM) using metal precursors, kerosene, and a surfactant. The product particles were characterized by transmission electron microscopy (TEM), nitrogen adsorption, and X-ray diffraction. Hollow γ-Al₂O₃ particles were produced from aluminum nitrate or chloride precursors dispersed in air, whereas dispersion of the precursor emulsion in oxygen resulted in solid α-Al₂O₃ particles. Hollow spheres were obtained also for TiO₂, ZrO₂, and Y₂O₃ by ECM of TiCl₄, zirconium oxynitrate, and yttrium nitrate in aqueous solution. A simple method was developed to predict the thickness and diameter of hollow particles using the nitrogen adsorption data and initial droplet concentration of the ECM spray. The TEM diameter and shell thickness of hollow particles were consistent with those predicted. In contrast, solid particles were formed by ECM for ZnO, Fe₂O₃, CeO₂, and MgO from aqueous solutions of their corresponding nitrates.     

Radiocoloring in planar graphs: Complexity and approximations

The Frequency Assignment Problem (FAP) in radio networks is the problem of assigning frequencies to transmitters, by exploiting frequency reuse while keeping signal interference to acceptable levels. The FAP is usually modelled by variations of the graph coloring problem. A Radiocoloring (RC) of a graph G(V,E) is an assignment function such that |Φ(u)-Φ(v)|2, when u,v are neighbors in G, and |Φ(u)-Φ(v)|1 when the distance of u,v in G is two. The number of discrete frequencies and the range of frequencies used are called order and span, respectively. The optimization versions of the Radiocoloring Problem (RCP) are to minimize the span or the order. In this paper we prove that the radiocoloring problem for general graphs is hard to approximate (unless NP=ZPP) within a factor of n^1/2-ε (for any ), where n is the number of vertices of the graph. However, when restricted to some special cases of graphs, the problem becomes easier. We prove that the min span RCP is NP-complete for planar graphs. Next, we provide an O(nΔ) time algorithm (|V|=n) which obtains a radiocoloring of a planar graph G that approximates the minimum order within a ratio which tends to 2 (where Δ the maximum degree of G). Finally, we provide a fully polynomial randomized approximation scheme (fpras) for the number of valid radiocolorings of a planar graph G with λ colors, in the case where λ4Δ+50.     

Hydrolysis rate of submicron Zn particles for solar H2 synthesis

The hydrolysis rate of Zn particles by up to 50 mol% water vapor in Ar gas was measured by thermogravimetric analysis at atmospheric pressure and 330–360 °C and quantified by a core-shell model. An initial ZnO layer led to an initially linear conversion profile attributed to a fast surface reaction (half-order with respect to water vapor mole fraction, y) followed by a parabolic conversion profile independent of y but dependent on Zn ion diffusion through a ZnO layer. The latter is most important for solar H₂ formation by the Zn/ZnO water-splitting cycle as it determines the required process residence time for Zn hydrolysis. A ready-to-use equation for calculation of ZnO and H₂ formation during Zn hydrolysis is proposed and compared to literature data revealing enhanced hydrolysis rates for submicron Zn particles.     

Silicon Fuel: A hydrogen storage material

Considerable effort is focused on developing alternative approaches to generating and storing energy to reduce the world's reliance on fossil fuels. Hydrogen offers one such alternative, which is zero-emission at the point of use when used to supply a fuel cell to generate electricity. However, the availability of hydrogen by methods that are both cost-effective and environmentally friendly remains a significant challenge.The formulation presented in this work, which we call Silicon Fuel, contains 90% silicon and can generate high hydrogen yields of 70% or more in just a few minutes. This means that the dry material effectively has a hydrogen content of at least 9 wt% and a realistic specific energy of at least 1.5 kWh/kg if the hydrogen supplies a fuel cell with 50% efficiency. As the hydrogen can be generated in a commercially useful time frame, it is suitable for applications such as automotive refuelling, where consumers expect to be able to refuel their vehicle within a few minutes.     

Aggregated mobility-based topology inference for fast sensor data collection

We investigate the problem of efficient data collection in wireless sensor networks where both the sensors and the sink move. We especially study the important, realistic case where the spatial distribution of sensors is non-uniform and their mobility is diverse and dynamic. The basic idea of our protocol is for the sink to benefit of the local information that sensors spread in the network as they move, in order to extract current local conditions and accordingly adjust its trajectory. Thus, sensory motion anyway present in the network serves as a low cost replacement of network information propagation. In particular, we investigate two variations of our method: a) the greedy motion of the sink towards the region of highest density each time and b) taking into account the aggregate density in wider network regions. An extensive comparative evaluation to relevant data collection methods (both randomized and optimized deterministic), demonstrates that our approach achieves significant performance gains, especially in non-uniform placements (but also in uniform ones). In fact, the greedy version of our approach is more suitable in networks where the concentration regions appear in a spatially balanced manner, while the aggregate scheme is more appropriate in networks where the concentration areas are geographically correlated. We also investigate the case of multiple sinks by suggesting appropriate distributed coordination methods.     

Adaptive lighting controllers using smart sensors

The aim of this paper is to present an advanced controller for artificial lights evaluated in several rooms in two European Hospitals located in Chania, Greece and Ancona, Italy. Fuzzy techniques have been used for the architecture of the controller. The energy efficiency of the controllers has been calculated by running the controller coupled with validated models of the RADIANCE back-wards ray tracing software. The input of the controller is the difference between the current illuminance value and the desired one, while the output is the change of the light level that should be applied in the artificial lights. Simulation results indicate significant energy saving potentials. Energy saving potential is calculated from the comparison of the current use of the artificial lights by the users and the proposed one. All simulation work has been conducted using Matlab and RADIANCE environment.