Area aggregation and time-scale modeling for sparse nonlinear networks

Model reduction and aggregation are of key importance for simulation and analysis of large-scale systems, such as molecular dynamics, large swarms of robotic vehicles, and animal aggregations. We study a nonlinear network which exhibits areas of internally dense and externally sparse interconnections. The densely connected nodes in these areas synchronize in the fast time-scale, and behave as aggregate nodes that dominate the slow dynamics of the network. We first derive a singular perturbation model which makes this time-scale separation explicit and, next, prove the validity of the reduced-model approximation on the infinite time interval.     

Exergy analyses of green hydrogen production methods from biogas-based electricity and sewage sludge

In this study, five models are considered for the use of biogas-based electricity and sewage sludge obtained from a municipal wastewater treatment plant for green hydrogen production. These models include alkaline, PEM, high temperature water electrolysis, alkaline hydrogen sulfide electrolysis and dark fermentation biohydrogen production processes. Energy and exergy analyses are performed on these models by applying thermodynamic procedures and the results are compared. The daily hydrogen production rates of the models are found as 594, 625.4, 868.6, 10.8 and 56.74 kg and the exergetic efficiencies of the models are calculated as 19.81, 20.66, 25.83, 24.86 and 60.54%, respectively. In terms of the exergetic efficiency, the dark fermentation biohydrogen production process is found to be superior to the other models, followed by the high temperature steam electrolysis process. This paper aims to determine the most appropriate model for a wastewater treatment plant among the considered models in terms of exergy efficiency.     

Automated major depressive disorder detection using melamine pattern with EEG signals

Applied Intelligence - Major depressive disorder (MDD) is one of the most common modern ailments affected huge population throughout the world. The electroencephalogram (EEG) signal is widely used...     

Wearable supercapacitors based on nickel tungstate decorated commercial cotton fabrics

Symmetric supercapacitors (SSCs) with remarkable energy storing capability, high specific power as well as long-term cyclic stability were fabricated from nickel tungstate (NiWO₄) @ nickel oxide (NiO_x) decorated commercial cotton fabrics (CCFs). A commercial cotton-based textile was first made conductive by the state of the art ultrasonic spray coating method. This was followed by chemical and electrochemical processes to decorate activated CCFs with NiO_x and NiWO₄, respectively. The assembled SSCs had the merit of high specific energy of 12 μWh cm⁻² at a specific power of 69 μW cm⁻² while showing reasonable cyclic stability. Fabricated devices retained over 80% of their initial capacitance after 5500 continuous charge/discharge cycles. The flexibility of the devices was investigated under bending, twisting, and folding providing reliable evidence on the wearability of the fabricated SSCs. Cyclic voltammograms of the fabricated NiWO₄@NiO_x@CCF SSCs showed only a slight change and retained over 95% of the capacitance under bending and folding. The fabricated NiWO₄@NiO_x@CCF SSCs, in this regard, are promising energy storage systems to power up high-performance wearable electronics.     

On the shear failure mode of granular column embedded unit cells subjected to static and cyclic shear loads

Since the initial conception of geosynthetic encased columns (GECs), exhaustion of column capacity due to vertical loads in bulging and punching failure modes were readily recognized. This lead to a vast majority of the available research on GECs to be about the behavior of columns under the action of vertical loads. Recently, two other likely and perhaps more dominant failure modes for granular columns namely, shear and bending failure modes, were identified. The purpose of this paper is to study the behavior of unit cells containing ordinary stone columns (OSCs) and GECs under static and cyclic lateral loads where shear failure of the column is imminent. 1-g physical tests are conducted with a novel apparatus, designated as Unit Cell Shear Device (UCSD), to model the behavior of the unit cells located close to the toe of an embankment where OSCs and GECs experience significant lateral loading. Overall failure envelope and strength parameters for GECs with varying reinforcement stiffnesses are quantified under static and cyclic lateral loading conditions. The distribution and magnitude of reinforcement strains in horizontal (hoop) and vertical direction of the columns are also considered.     

The Tigris hydropower system operations: the need for an integrated approach

The Tigris hydropower system is analyzed through an integrated operational policy. The operation algorithm is formulated in terms of non-linear programming to maximize energy production while satisfying water demands in the basin. The system is optimized for different cases, and the effects of system modifications in terms of the reservoir volume of Ilisu Dam and the demand constraints are examined. In addition, the state of the Garzan subsystem is analyzed to explore plant utilization when optimizing the entire system operations. The results show the necessity of such an integrated operation plan to supply water demands in the basin.     

A deep feature warehouse and iterative MRMR based handwritten signature verification method

Multimedia Tools and Applications - Offline handwritten signature verification has been widely used for document forensics and biometrics, and it is a popular issue. Deep learning models have...     

Ensemble residual network-based gender and activity recognition method with signals

The Journal of Supercomputing - Nowadays, deep learning is one of the popular research areas of the computer sciences, and many deep networks have been proposed to solve artificial intelligence and...     

Determination of laminar and turbulent flow ranges through vertical packed beds in terms of particle friction factors

Despite the presence of a variety of studies dealing with the magnitude of particle Reynolds number, Re_p defining transition from laminar to turbulent regime for flow through packed beds, the manner is still one of the unknowns. An approach based on the experimental data concerning upward airflow through fixed cylindrical packed beds is presented in this paper. The utilized packed beds had the following ranges of; sphericity, Φ, 0.55 ? Φ ? 1.00, packing material diameter to bed length ratio, D_p/L, 0.04 ? D_p/L ? 0.72, and bed porosity, ε, 0.36 ? ε ? 0.56. The test cases covered the ranges of particle Reynolds number, Re_p 708 ? Re_p ? 7772 and particle Froude number; Fr_p 2.86 ? Fr_p ? 10.39. The measurements of pressure drop through packed bed; ΔP_Bed and superficial mean exit velocity; U are used to determine bed frictional effects in reference to the available literature on particle friction factors, f_p. The magnitude of Re_p defining transition is assumed to be 2000 with particular emphasis to the flow dynamics. The definitions of Bird et al. [R.B. Bird, W.E. Stewart, E.N. Lightfoot, Transport Phenomena, John Wiley and Sons, NY, 1960] are used to calculate f_p. The calculated f_p for the covered test cases are given as a function of pressure coefficient, ΔP* and Re_p, Fr_p, Φ, ε, D_p/L in the approximate ranges of laminar and turbulent flow for Re_p < 2000 and Re_p > 2000, respectively. The proposed separate equations of f_p = f_p(ΔP*, Re_p, Fr_p, Φ, ε, D_p/L) are satisfied for laminar and turbulent flows with corresponding average error margins of ±7.6% and ±18%. Furthermore ranges of transitional and fully rough flow through packed beds are estimated as 2000 ? Re_p ? 4000 and Re_p > 5000 with an analogy to the well-known Moody Chart in pipe flows.