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Iron oxide inside SBA-15 modified with amino groups as reusable adsorbent for highly efficient removal of glyphosate from water
No full textIron oxide clusters were incorporated into amino-functionalized SBA-15 in order to obtain a magnetically recoverable adsorbent. The physical-chemical properties of the material were characterized by FE-SEM, STEM, XRD, TGA, XPS, FT-IR and acid-base titration analysis. Iron oxide nanoparticles were uniformly dispersed into the pore of mesoporous silica and that the adsorbent is characterized high specific surface area (177 m2/g) and accessible porosity. The sorbent was successfully tested for the removal of glyphosate in real water matrices. Despite the significant content of inorganic ions, a quantitative removal of the contaminant was found. The complete regeneration of the sorbent after the adsorption process through diluted NaOH solution was also proved
A study of the main factors affecting the performance of self-sensing concrete
No full textConcrete sensors, which are manufactured by mixing conductive fibres (such as carbon nanotubes (CNTs)) with concrete, are one of the most significant and economical types of sensor. Two main factors affecting the performance of concrete sensors are the amount of CNTs and the quality of their dispersion in the mixture with regard to the combined effects of the surfactant composition and CNTs dispersed with different levels of energy. The goal of this research was to evaluate the effects of the main parameters affecting concrete sensor performance using various criteria (sensitivity of the sensor, standard deviation of the prediction error, repeatability, cross-correlation and hysteresis) in both static and dynamic loading regimes. Dynamic criteria such as sensitivity, internal repeatability, cross-correlation and hysteresis showed that the energy levels for the dispersion of CNTs have a greater effect on improving sensor performance than the amount of CNTs. On the contrary, the repeatability indicated that the amount of CNTs has a greater effect on sensor performance than the dispersion quality (energy level) of the CNTs. On the whole, the sensor produced with 0·15 wt% (by weight of cement) CNTs, superplasticiser and sodium dodecyl sulfate as a surfactant using the maximum energy level (ultrasonic bath for 2 h and 90 min of probe's ultrasonication) offered the best performance both in the static and dynamic load regimes
Leading impulse response identification via the Elastic Net criterion
No full textThis paper deals with the problem of finding a low-complexity estimate of the impulse response of a linear time-invariant discrete-time dynamic system from noise-corrupted input-output data. To this purpose, we introduce an identification criterion formed by the average (over the input perturbations) of a standard prediction error cost, plus an l1 regularization term which promotes sparse solutions. While it is well known that such criteria do provide solutions with many zeros, a critical issue in our identification context is where these zeros are located, since sensible low-order models should be zero in the tail of the impulse response. The flavor of the key results in this paper is that, under quite standard assumptions (such as i.i.d. input and noise sequences and system stability), the estimate of the impulse response resulting from the proposed criterion is indeed identically zero from a certain time index n_l (named the leading order) onwards, with arbitrarily high probability, for a sufficiently large data cardinality N. Numerical experiments are reported that support the theoretical results, and comparisons are made with some other state-of-the-art methodologies
Mitochondria and neurodegenerative diseases: the promising role of nanotechnology in targeted drug delivery
No full textEffects of the distance from a diffusive surface on the objective and perceptual evaluation of the sound field in a small simulated variable-acoustics hall
No full textSimulations of the acoustic effects that diffusive surfaces have on the objective acoustic parameters and on sound perception have not yet been fully understood. To this end, acoustic simulations have been performed in Odeon in the model of a variable-acoustic concert hall. This paper is presented as a follow-up study to a previous paper that dealt with in-field measurements only. As in measurements, a diffusive and a reflective condition of one of the lateral walls have been considered in the room models. Two modeling alternatives of the diffusive condition, that is, (a) a flat surface with high scattering coefficient applied; and (b) a triangular relief modeled including edge diffraction, have been investigated. Objective acoustic parameters, such as early decay time (EDT), reverberation time (T30), clarity (C80), definition (D50), and interaural cross correlation (IACC), have been compared between the two conditions. Moreover, an auditory experiment has been performed to determine the maximum distance from a diffusive surface at which the simulated acoustic scattering effects are still audible. Although the simulated objective results showed a good match with measured values, the subjective results showed that the differences between the diffuse and reflective conditions become significant when model (b) is used
A Phonatory System Simulator for testing purposes of voice-monitoring contact sensors
No full textMonitoring the health of the phonatory system plays a key role for the voice professionals, which are people who use the voice as a work tool. The voice quality can be assessed by means of parameters extracted from the vocal signal sensed by a contact sensor placed at the base of the neck, that is sensitive to the skin vibration related to the phonation. The use of a contact sensor is preferable to a microphone in air because of its lower sensitivity to the acoustical background noise. This paper focus on the development of a system for the characterization of the contact sensor that can be used for this purpose: an apparatus that can mimic the phonatory system and can act like a standard for testing the sensors. Such a system has been created and preliminary tested and characterized, in order to point out the similarity with the real phonatory system and to bring out any critical issue
Cyclic oxidation in burner rig of TiAlN coating deposited on Ti-48Al-2Cr-2Nb by reactive HiPIMS
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Experimental and Numerical study of Air thrust bearing controlled by diaphragm valve
No full textAero-static thrust bearings offer some distinct advantages in comparison with contact bearings as there is no contact between the moving and stationary parts, thus there is no wear, limited heat generation and long life can be achieved. Moreover, linear positioning control is not affected by the highly nonlinear friction forces, and high precision positioning or high speed can be achieved. The main drawbacks of aerostatic bearings are low stiffness and load capacity and sometimes poor damping in comparison to contact bearings, so that their application in some sectors, e.g. machine tools, is less popular. Active compensation methods can be used as a solution for this problem. Electronic control with piezo actuators give generally good results in both static and dynamic conditions but they are expensive do to use of many sensors and piezo actuators for each pad. In addition in this type of methods, special design is necessary for each air bearing and normal commercial air bearings cannot be used. Pure pneumatic control is an interesting alternative solution in terms of performances and cost. This thesis presents designing, modelling and test of pneumatic valve which is an upstream restrictor and can control the air flow to improve the stiffness of any commercial thrust bearing. The static experiments show that the active system can improve the static stiffness significantly but it was in cost of losing the load carrying capacity. Different improvement have been made to improve the valve design in order to improve the load carrying capacity. In the final design it is possible to use the active system instead of wide range of commercial thrust air bearing with higher load carrying capacity and stiffness. In this study the numerical simulation of grooved feeding thrust air bearings is done for the first time. These type of bearing was selected as a passive commercial pad due to high stiffness of these type of air pads in compare with other feeding methods. The lumped numerical model is used to simulate the active system. The experimental results show that the proposed model can adequately describe the performance of grooved pad and pneumatic valve. Two different type of dynamic experiment is performed in order to identify the dynamic characteristics of the system like damping and dynamic stiffness in order to find the stability range which is important especially for pneumatic control