A hybrid encryption/hiding method for secure transmission of biometric data in multimodal authentication system

Biometric security is a fast growing area that gains an increasing interest in the last decades. Digital encryption and hiding techniques provide an efficient solution to protect biometric data from accidental or intentional attacks. In this paper, a highly secure encryption/hiding scheme is proposed to ensure secure transmission of biometric data in multimodal biometric identification/authentication system. The secret fingerprint and iris vectors are sparsely approximated using accelerated iterative hard thresholding technique and then embedded in the host Slantlet-SVD domain of face image. Experiments demonstrate the efficiency of our technique for both encryption and hiding purpose, where the secret biometric information is well encrypted and still extractable with high fidelity even though the carrier image is seriously corrupted. Our experimental results show the efficiency of the proposed technique in term of robustness to attacks, Invisibility, and security.

     

Strategy for Complete Nitrogen Removal in Bioreactor Landfills

Waste acclimation and batch microcosm studies containing digested municipal solid waste were conducted at different temperatures (22, 35, and 45°C) and gas-phase oxygen concentrations (0.7–100%, by volume) to provide guidance for field-scale implementation of in situ nitrogen removal processes. Results demonstrate that in situ ammonia–nitrogen is feasible in decomposed aerated solid waste environments at the gas-phase oxygen concentrations and temperatures evaluated and the potential for simultaneous nitrification and denitrification in field-scale bioreactor landfills is significant due to the presence of both aerobic and anoxic areas. Small amounts of oxygen were found sufficient for nitrification/ammonia removal to proceed, although removal rates increase with oxygen concentration. Laboratory results suggest field-scale implementation of in situ nitrogen removal occur in small dedicated treatment zones containing previously degraded waste (later in the life of a bioreactor landfill). Model simulations indicate removal of ammonia–nitrogen to low levels can occur with relatively short aeration depths (depth estimates ranged from 1.6 to 7.2?m below the point of leachate injection). Field-scale verification of these depth estimates is required prior to routine acceptance.     

Stationary bifurcation control of systems with uncontrollable linearization

Stationary bifurcation control is studied under the assumption that the critical zero eigenvalue is uncontrollable for the linearized system. The development facilitates explicit construction of feedback control laws that render the bifurcation supercritical. Thus, the bifurcated equilibria in the controlled system are guaranteed stable. Both pitchfork bifurcation and transcritical bifurcation are addressed. The results obtained for pitchfork bifurcations apply to general non-linear models smooth in the state and the control. For transcritical bifurcations,the results require the system to be affine in the control.     

High-voltage solar cell with high short wavelength sensitivity on the base of GaAs–AlGaAs heterosystem

In this contribution two structures of high-voltage solar cells are discussed and analyzed. The first one is a high-voltage solar cell with only vertical p-n junctions. Therefore, the photo-current value of this structure and — consequently — the efficiency are low because of the small active p-n junction area. In order to improve the main parameters of the above mentioned structure — particularly the photo-current and the efficiency — a new structure of high-voltage solar cells, combining both horizontal and vertical p-n junctions is suggested. This structure has been elaborated by combining liquid phase epitaxy with gas-phase zinc diffusion technologies, and was grown on semi-insulating GaAs substrates with ρ=10¹²Ω cm. This new structure has shown better parameters than the parameters of the high-voltage solar cell with only vertical p-n junctions. It exhibits appreciable values of photo-current and output voltage. Furthermore, this structure provides both high short wavelength sensitivity, and independent efficiencies of spectral composition of solar radiation. Therefore, it can be successfully utilized in many aspects of modern science and technology, particularly as power supplies in high-located areas, and as photoacceptors of ultra-violet radiation.     

Three cascade solar cells with graded band-gap layer on the base of GaAs–AlGaAs heterosystem

A new structure of three cascade solar cells with graded band-gap layer on the base of GaAs–AlGaAs heterosystem is designed to decrease the thermal losses, arising as a result of absorption of short-wavelength radiation. These solar cells were created by combining liquid-phase epitaxy with gas-phase zinc diffusion technologies. In these structures multilayer cascade elements reduce losses, caused by generation of “hot” carriers and the upper graded band-gap layer improves the conversion of short-wavelength radiation. The cell structure exhibited high short-wavelength sensitivity and the following parameters (under 1-sun conditions): open-circuit voltage (V_oc=1.03 V); short-circuit current (I_sc=24.9 mA/cm²); fill factor (FF=0.74) and efficiency (η=22.3%). Therefore it can be successfully utilized as power supplies in high-located areas, and as sensors of ultra-violet radiation.     

Modeling Nonlinear Anisotropic Elastic Properties of Unbound Granular Bases Using Microstructure Distribution Tensors

The resilient properties of unbound aggregate bases are important parameters in the design of asphalt pavements. Previous studies have shown that these resilient properties exhibit nonlinear and transverse anisotropic characteristics. The paper in hand presents a micromechanics-based approach to model the nonlinear and anisotropic properties of unbound aggregate bases. The anisotropic behavior is captured using two microstructure parameters representing the preferred orientation of aggregate particles, and the ratio of the normal contact stiffness to shear contact stiffness among particles. The nonlinear response is modeled using a relationship that relates the shear modulus to particle packing, material properties, particle size, and confining pressure. The micromechanics model is used to represent the resilient properties for a total of 18 different combinations of material conditions with different aggregate types, moisture contents, and gradation characteristics. Anisotropic and nonlinear resilient properties were measured at ten different stress states for each of the material conditions. The results presented in this paper show that the micromechanics model is capable of successfully representing the experimental measurements.     

Influence of different sources of microstructural heterogeneity on the degradation of asphalt mixtures

The response and degradation of the hot mix asphalt (HMA) materials used in pavement structures are affected by their inherent heterogeneity. The objective of this work is to study the impact of two different sources of HMA heterogeneity in the uncertainty of the mechanical moisture degradation of HMA. The first source of heterogeneity is the spatial variability of the properties of the bulk fine aggregate matrix (FAM) of the mixture, and the second is the location and shape of the coarse aggregate particles. The heterogeneity of the bulk FAM phase was modelled using a random field technique, while that of the coarse aggregates was accounted for by randomly generating realistic probable sets of aggregate particles. Thus, ‘computational replicates’ of HMA microstructures were generated and subjected to moisture diffusion and mechanical loading using a finite element approach. In the mechanical simulations, a non-linear viscoelastic moisture damage constitutive relationship based on continuum damage mechanics theory was selected to characterise the response of the bulk FAM phase. The results show that conducting computational simulations with realistic HMA microstructures that properly capture the heterogeneity of the material is useful to quantify the mean values and dispersion (i.e. uncertainty) associated with the response and degradation of the mixture. This information, which cannot be easily obtained in the field or in the laboratory due to the difficulty of acquiring a sufficient amount of data, is useful to conduct structural reliability analysis and to predict the life cycle behaviour of the material.