Local feature selection for multiple instance learning

Journal of Intelligent Information Systems - We propose a local feature selection method for the Multiple Instance Learning (MIL) framework. Unlike conventional feature selection algorithms that...     

Using bent carbon nanotubes for the fabrication of electromechanical switches

An electromechanical switch based on bent carbon nanotubes was fabricated. The shape and structure of the bent carbon nanotubes allows one to produce a low cost and low working voltage switch. The fabrication process is free of any nanolithography. The electrical characteristics of the fabricated device were investigated, both experimentally and theoretically. Actuation of the fabricated device shows hysteresis behavior in the measured I–V curves depending on the structural parameters of the bent nanotubes. The relationship between the pull-in voltage and the morphology of the bent nanotubes was studied by the obtained hysteresis curves. A scanning electron microscope was used for structural analysis. This study introduced an easy way to fabricate electromechanical switches with controllable on/off states.     

Use of a selective extractant-impregnated resin for removal of Pb(II) ion from waters and wastewaters: Kinetics,equilibrium and thermodynamic study

Adsorption of Pb(II) ion by a novel extractant-impregnated resin, EIR, was studied as a function of various experimental parameters using batch adsorption experiments. The new EIR was prepared by impregnating gallocyanine (GCN) onto Amberlite XAD-16 resin beads. The EIR was characterized by nitrogen analysis and SEM micrographs. The new EIR showed excellent selectivity factor values (α) for Pb(II) adsorption respect to other metal ions. The effects of some chemical and physical variables were evaluated and the optimum conditions were found for Pb(II) removal from aqueous solutions. The equilibrium adsorption isotherm was fitted with the Langmuir adsorption model. The maximum adsorption capacity (q_max) of EIR for Pb(II) ions was found to be 367.92 mg g⁻¹. The kinetic studies showed that the intra-particle diffusion is the rate-controlling step. Also, the intra-particle diffusion coefficients, D_ip values, were of the order of 10⁻¹² m² s⁻¹. The values of enthalpy (ΔH°) were positive, which confirms the endothermic nature of adsorption process. Also, the positive entropy changes (ΔS°) were showed that the randomness increased along with the adsorption process. In addition, the obtained negative values of Gibbs free energy (ΔG°) indicated feasible and spontaneous nature of the adsorption process at different temperatures. The new adsorbent was very stable so that it can be successfully used for many consecutive cycles without significant loss in its adsorption capacity.     

In vitro bioactivity and biocompatibility of lithium substituted 45S5 bioglass

In this study, different concentrations of Li₂O (0–12 wt.%) were substituted for Na₂O in 45S5 bioglass® and the effect of these substitutions on both in vitro apatite formation ability and osteoblastic cell responses was studied. For these purposes, the structural and topographical properties of the glasses were studied using, XRD, FTIR, SEM/EDXA and AFM techniques, before and after storing in simulated body fluid for different time intervals. Additionally, the proliferation rate and activity of newborn rat calvaria-derived osteoblastic cells on different samples were examined by using dimethylthiazol diphenyl tetrazolium bromide (MTT) and alkaline phosphatase (ALP) assessment methods. From XRD and FTIR data, it was found that poor crystalline carbonated nanoapatite phase was formed on the surface of glasses with maximum concentration of Li or without Li, while at low substitutions an inhibition of apatite formation was observed. The apatite layer formed on the surfaces of the glasses had similar morphology, flakes which tightly entangled to others. All samples had the same surface roughness before soaking but different values after that. It was found that both proliferation rate and alkaline phosphatase activity of the cells cultured on Li-substituted glasses were higher than those of Li-free sample in a dose-dependent manner. The results suggest that lithia-modified glasses may be successfully used as bone defect filler even with more effectiveness than 45S5 bioglass®.     

An uncertainty compensator for robust control of wheeled mobile robots

This paper proposes an uncertainty compensator to design a novel robust control for mobile robots with dynamic and kinematic uncertainties. A novel gradient-based adaptive fuzzy estimator is developed to compensate uncertainties with minimum required feedback signals. As a novelty, the proposed approach uses the tracking error and its first time derivative to form the estimation error of uncertainty, and guarantees that both the estimation error and tracking error converge asymmetrically to ignorable value. Advantages of the proposed robust control are simplicity in design, robustness against uncertainties, guaranteed stability, and good control performance. The control approach is verified by stability analysis. Simulation results and experimental results illustrate the effectiveness of the proposed control. Experimental evaluation of the proposed controller is expressed for two different low-cost nonholonomic wheeled mobile robots. The proposed control design is compared with an adaptive control approach to confirm the superiority of the proposed approach in terms of precision, simplicity of design, and computations.     

An Analytical Hierarchy Model for Assessing Global Water Productivity of Irrigation Networks in Iran

Water Resources Management - Water management decisions in irrigation networks are often characterized by complexity, irreversibility and uncertainty. In the present study, an analytical hierarchy...     

Passive beamforming in co-prime sensor arrays using NSCB method under original pattern perturbations minimization

Multidimensional Systems and Signal Processing - The co-prime sensor array (CSA), which is an effective sparse configuration, has the drawback of generating grating lobes in passive beamforming. To...     

The effect of the initial charge temperature under various injection timings on the second law terms in a direct injection SI hydrogen engine

In this study, the effect of the initial charge temperature on the second law terms under the various injection timings in a direct injection spark ignition hydrogen fuelled engine has been performed theoretically during compression, combustion and expansion processes of the engine cycle. The first law analysis is done by using the results of a three dimensional CFD code. The results show a good agreement with the experimental data. Also for the second law analysis, a developed in house computational code is applied. The results reveal that the indicated work availability is more affected by varying hydrogen injection timing in comparison with other second law terms. Also increasing the initial charge temperature causes the heat loss availability and exhaust gas availability be increased and indicated work availability, combustion irreversibility and entropy generation be decreased.     

In situ forming poly(lactic acid-co-glycolic acid) implants containing leuprolide acetate/β-cyclodextrin complexes: preparation,characterization, and in vitro drug release

In situ forming implants (ISIs) based on poly(lactic acid-co-glycolic acid) (PLGA) containing leuprolide acetate/β-cyclodextrin (LA/β-CD) complexes were prepared. Incorporation of LA or complexes did not change T_g values of ISIs (48.4–49.6°C). ISIs containing complexes with more β-CD content showed higher surface and bulk porosity. Higher β-CD portion in complexes improved solvent release, decreased initial burst release and facilitated diffusion out of drug for corresponding ISIs. Complexation of LA with β-CD (1/10, w/w) significantly improved its stability within PLGA matrix before release (total LA release of 91.3%). ISIs did not show any cellular cytotoxic effects against L929 fibroblast cells.     

Effectively designed shell‐tube heat exchangers considering cost minimization and energy management

Cost optimization, which is expressed as a set of analytical variables, is a key objective in economic design approaches of shell‐and‐tube heat exchangers. This study has provided new design techniques based on tube bundle effect on the economic optimization design of shell‐and‐tube heat exchangers. Also the objective of this paper is to develop the cost estimating for the new modified shell‐and‐tube heat exchangers by introducing new objective functions. According to the results the best configuration choice will obviously be the one with the least irreversibility, that is, with the lowest exergy destruction rate and lower annual capital cost. Also, the combined reduction of annual capital investment and operating cost by the new design technique led to a decrease in the overall costs of about 10% to 24% in comparison with original design. So the proposed design technique shows potential for improvement and economic optimization of shell‐and‐tube heat exchangers.