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In this paper, an interface circuit for far-distance energy harvesting from magnetic field of overhead lines is presented. Due to the specific conditions of this type of energy harvesting, such as low available power, low induced voltage in the energy harvester coil, and change of energy harvester impedance, a direct AC/DC switching converter should be used. A maximum power point tracking solution is also necessary to guarantee impedance matching at different operation points. Since the harvested power is in the range of a hundred micro-watts, the power usage of the control circuitry is of significant importance and conventional design approaches based on microcontrollers and FPGAs which require ADCs, DACs and digital signal processing cannot be applied here. The proposed processing circuitry presented in this paper uses three feedback loops to perform the harvesting and energy transfer control. Only low-power comparators and basic digital gates are used as signal-processing elements to limit the power dissipation of the designed control blocks. The impedance matching inner loop samples the H-bridge voltage drop to extract the output load current and perform PWM impedance matching while transferring a rectified current to the output capacitor. Another inner feedback loop is used at the output capacitor using two-level comparison to regulate the output voltage. For maximum power point tracking an outer feedback loop samples the output voltage transfer rate and using a 50 Hz reference generator, adjusts the parameters of the impedance matching circuit of the first inner loop. With the proposed approach, in addition to converting the AC input power to a DC voltage, the output load is regulated at a fixed potential and using the MPPT control loop, the maximum power available from the coil is delivered to the output with relatively low dissipation. The proposed circuit is evaluated using a 0.18 μm standard CMOS technology and operates as a self-powered circuit without an external power source. Based on the obtained results, the efficiency of the proposed circuit at 119 µW input power is about 92.4%, and the MPPT efficiency is about 95%, which is suitable for low-power applications. [ABSTRACT FROM AUTHOR]

Energy harvesting from the magnetic field around overhead power lines is an effective approach to supply power for sensor nodes used for measuring weather conditions and power line monitoring. Due to the low intensity of the magnetic field at far distances from the overhead line, the power extracted by the energy harvester coil in this method is low and in the order of a few hundred μWs. Thus, it is necessary to use interface circuits including AC-DC voltage converters and power management circuits with low power consumption and high efficiency. In this paper, a rectifier-less single stage AC-DC voltage converter is used to convert the alternating magnetic field to a DC voltage, as well as providing matching conditions to transfer maximum power. In the proposed structure, a low power impedance matching PWM generator is presented which uses pulse width domain signal processing, and thus reduces power consumption. The performance of the proposed circuit is demonstrated using theoretical elaborations. In addition, the proposed structure is simulated using a 0.18 μm standard CMOS technology, based on which the circuit power dissipation is about 7 μW at 70 kHz and the proposed circuit efficiency is about 94.5%. The maximum power transferring efficiency is about 96% at 120 µW input power. [ABSTRACT FROM AUTHOR]

Protein aggregation into gel networks is of immense importance in diverse areas from food science to medical research; however, it remains a grand challenge as the underlying molecular interactions are complex, difficult to access experimentally, and to model computationally. Early stages of gelation often involve protein aggregation into protein clusters that later on aggregate into a gel network. Recently synthesized protein microparticles allow direct control of these early stages of aggregation, decoupling them from the subsequent gelation stages. Here, by following the gelation of protein microparticles directly at the particle scale, we elucidate in detail the emergence of a percolating structure and the onset of rigidity as measured by microrheology. We find that the largest particle cluster, correlation length, and degree of polymerization all diverge with power laws, while the particles bind irreversibly indicating a nonequilibrium percolation process, in agreement with recent results on weakly attractive colloids. Concomitantly, the elastic modulus increases in a power-law fashion as determined by microrheology. These results give a consistent microscopic picture of the emergence of rigidity in a nonequilibrium percolation process that likely underlies the gelation in many more systems such as proteins, and other strongly interacting structures originating from (bio)molecules. [ABSTRACT FROM AUTHOR]

A comparison study of various models in investigating the Coulomb logarithm (CL) for a wide range of densities and temperatures is carried out. Using two known reference parameters, the ion coupling Γ and the electron degeneracy Θ , the capability of a recently proposed coupled Gericke–Murillo–Schlanges (CGMS) model in evaluating the CL is compared with other previous models—the Gericke–Murillo–Schlanges (GMS) model, the Landau–Spitzer (LS), the Brown–Preston–Singleton (BPS), the classical molecular dynamics (MD), and Khrapak (KH) model. It is observed that the CGMS model shows reliable results in both weakly and strongly coupled regimes. Moreover, the effects of using these models on studying electron heat transfer and conductivity coefficient within the weakly coupled and strongly coupled plasmas are examined. [ABSTRACT FROM AUTHOR]

Contamination of urban water distribution systems (WDS) is a critical issue due to the number of victims that might be impacted in a short period of time. Any effective rapid emergency response plan for reducing the number of sick people or deaths among those drinking the polluted water requires a reliable forecast of the water contamination zoning map (CZM). The water CZM is a visual representation of the spread of contamination at the time of contamination detection. This study presents a novel methodology based on the rough set theory (RST) for real-time forecasting of the CZM caused by simultaneous multi-point contamination injection in WDS. Our proposed methodology consists of (i) a Monte Carlo simulation model to capture the uncertainties in a multi-point deliberate contamination, (ii) a numerical simulation model for simulating pipe flow, and (iii) a rough set-based technique for real-time CZM for a WDS equipped with a set of monitoring stations. The proposed methodology can be used for any type of random contamination of WDSs as well as emergencies in deliberate contamination of water distribution networks. [ABSTRACT FROM AUTHOR]

Sensor network architectures have gained significant attention in acquiring data over widespread areas. To avoid wiring and power complexities, self-powered operation is desirable in these sensors. For this purpose, low voltage and low power characteristics of the internal electronic building blocks is of significant importance. Since sensor architectures usually require voltage reference circuitry, in this paper, a low voltage, low power bandgap reference circuit block is presented. Using a new two stage topology, the line sensitivity is reduced to a significantly low value of 0.28%/V over a wider power supply range of 0.2 V to 2 V. Due to the use of MOSFETs in the subthreshold region, low voltage and low power operation of about 41 pW at 0.2 V is obtained. Furthermore by introducing a novel cross coupled architecture, the temperature coefficient is enhanced considerably. An average temperature coefficient of 247 ppm/°C is obtained at different corners. The performance of the architecture is studied in a 0.18 µm process using post layout and Monte Carlo evaluations. The evaluation results show improvements in both line sensitivity and temperature coefficients compared with previous work. [ABSTRACT FROM AUTHOR]

Abstract.: A granular mixture of identical particles of different densities can be segregated when the system is shaken. We present an efficient method of continuously segregating a flow of randomly mixed identical spherical particles of different densities by shaking them in a quasi-two-dimensional container with a sawtooth-shaped base. Using numerical simulation we study the effect of direction of shaking (horizontal/vertical), geometry of the sawtooth, and the friction coefficient between the grains and the container walls on the segregation quality. Finally by performing experiments on the same system we compare our simulation results with the experimental results. The good agreement between our simulation and experiment indicates the validity of our simulation approach and will provide a practical way for granular segregation in industrial applications. Graphical abstract: [ABSTRACT FROM AUTHOR]

Nanosized filler particles enhance the mechanical properties of polymer composites in a size-dependent fashion. This is puzzling, because classical elasticity is inherently scale-free, and models for the elasticity of composite systems never predict a filler-size dependence. Here, we study the industrially important system of silica-filled rubbers, together with a well-characterized model-filled crosslinked gel and show that at high filler content both the linear and nonlinear elastic properties of these systems exhibit a unique scaling proportional to the cube of the volume fraction divided by the particle size. This remarkable behavior makes it possible to predict the full mechanical response of particle-filled rubbers for small but finite deformations based solely on the rheology of the matrix and the size and modulus of the filler particles. [ABSTRACT FROM AUTHOR]

Zinc tin oxide (ZnSnO, ZTO) nano-structured was prepared by green hydrothermal route for dye-sensitized solar cell. The ZTO was coated on fluorine doped tin oxide glass (fluorine doped tin oxide, FTO glass with surface resistivity of 8-10 Ω/sq) as working electrode by Doctor Blade and spin coating techniques. The ZTO nano-composite was characterized by X-ray diffraction (XRD), fourier transform infrared, field emission scanning electron microscopy, energy dispersive X-ray spectrometry, and UV-Vis diffuse reflectance (DRS) spectroscopy. XRD results of ZTO showed cubic spinel structure of ZnSnO. FESEM results showed spherical particles with an average grain size of about 46 nm. The DRS spectra of the ZTO nano-composite showed an optical band gap energy of 3.35 eV, which is relatively lower than that of bare ZnO (3.42 eV). The reduced band gap energy lowered the rate of electron-hole pair recombination and increased the photovoltage (Voc). An enhancement of 60% in photo-voltage (Voc) was observed when nano-composite ZTO was used as working electrode compared to zinc oxide under the illumination of one sun (AM 1.5, 100 mW cm). The efficiency of the working electrodes using ZnSnO nano-composite was increased 40% compared to simple zinc oxide. The enhanced photo-voltage (Voc) may be attributed to higher Fermi level of the ZnSnO and reduced band gap. [ABSTRACT FROM AUTHOR]

Abstract.: We study the translocation mechanism of a granular chain in a horizontally vibrated saw-tooth channel using MD simulations and macro-scale experiments and show that the translocation speed is independent of the chain length as long as the chain length is larger than the spatial period of the saw-tooth. With the help of simulation, we explore the effect of geometry of the container and frequency and amplitude of vibration as well as chain flexibility on the chain drift speed. We observe that the most efficient transport is achieved when one of the channel walls is shifted with respect to the other wall by an amount equal to half the spatial period of the saw-tooth. We define a persistence length for the chain and show that the translocation speed depends on the ratio of persistence length over the spatial period of the saw-tooth. The optimum translocation occurs when this ratio is about 0.4. We also determine the optimum saw-tooth angle for the translocation of the chain as well as the optimum distance between the two walls. Some properties of this system are similar to those of polymer systems. Graphical abstract: [ABSTRACT FROM AUTHOR]

Digital images can suffer from periodic noise, resulting in the appearance of repetitive patterns on the image data and quality degradation. In order to effectively reduce the periodic noise effects, a novel adaptive Gaussian notch filter is proposed in this paper. In the presented method, the frequency regions that correspond to noise are determined by applying a segmentation algorithm on the spectral band of the noisy image using an adaptive threshold. Then, a region growing algorithm tries to determine the bandwidth of each periodic noise component separately. Subsequently, proper Gaussian notch filters are used to decrease the periodic noises only at the contaminated noise frequencies. The proposed filter and some other well-known filters including the frequency domain mean and median filters and also the traditional Gaussian notch filter are compared to evaluate the effectiveness of the approach. The results in different conditions show that the proposed filter gains higher performance both visually and quantitatively with lower computational cost. Furthermore, compared with the other methods, the proposed filter does not need any tuning and parameter adjustments. [ABSTRACT FROM AUTHOR]

Granular segregation is a common, yet still puzzling, phenomenon encountered in many natural and engineering processes. Here, we experimentally investigate the effect of particles cohesion on segregation in dry monodisperse and bidisperse systems using a rotating drum mixer. Chemical silanization, glass surface functionalization via a Silane coupling agent, is used to produce cohesive dry glass particles. The cohesive force between the particles is controlled by varying the reaction duration of the silanization process, and is measured using an in-house device specifically designed for this study. The effects of the cohesive force on flow and segregation are then explored and discussed. For monosized particulate systems, while cohesionless particles perfectly mix when tumbled, highly cohesive particles segregate. For bidisperse mixtures of particles, an adequate cohesion-tuning reduces segregation and enhances mixing. Based on these results, a simple scheme is proposed to describe the system's mixing behaviour with important implications for the control of segregation or mixing in particulate industrial processes. [ABSTRACT FROM AUTHOR]

Insight into crumpling or compaction of one-dimensional objects is important for understanding biopolymer packaging and designing innovative technological devices. By compacting various types of wires in rigid confinements and characterizing the morphology of the resulting crumpled structures, here, we report how friction, plasticity and torsion enhance disorder, leading to a transition from coiled to folded morphologies. In the latter case, where folding dominates the crumpling process, we find that reducing the relative wire thickness counter-intuitively causes the maximum packing density to decrease. The segment size distribution gradually becomes more asymmetric during compaction, reflecting an increase of spatial correlations. We introduce a self-avoiding random walk model and verify that the cumulative injected wire length follows a universal dependence on segment size, allowing for the prediction of the efficiency of compaction as a function of material properties, container size and injection force. [ABSTRACT FROM AUTHOR]