Low temperature electrical transport properties of carbon matrix containing iron nanoparticles

We present a comparative study of the low temperature electrical transport properties of the carbon matrix containing iron nanoparticles and the films. The conductivity of the nanoparticles located just below the metal-insulator transition exhibits metallic behavior with a logarithmic temperature dependence over a large temperature interval. The zero-field conductivity and the negative magnetoresistance, showing a characteristic upturn at liquid helium temperature, are consistently explained by incorporating the Kondo relation and the two dimensional electron-electron interaction. The films, in contrast, exhibit a crossover of the conductivity from power-law dependence at high temperatures to an activated hopping law dependence in the low temperature region. The transition is attributed to changes in the energy dependence of the density of states near the Fermi level. The observed magnetoresistance is discussed in terms of quantum interference effect on a three-dimensional variable range hopping mechanism.

Electrical properties of nickel-related deep levels in silicon

Electrically active deep levels related to nickel in silicon are studied under different diffusion conditions, quenching modes, and annealing conditions. The main nickel-related level is at Ev+0.32 eV. Levels at Ev+0.15 and Ev+0.54 eV are not related to nickel while those at Ev+0.50 and Ev+0.28 eV may be nickel related. Their concentrations depend on the quenching mode. There is no nickel-related level in the upper half of the band gap. The complicated annealing behavior of the main nickel-related level is explained on the basis of the formation and dissociation of a nickel-vacany complex. Journal of Applied Physics is copyrighted by The American Institute of Physics.

Electrical transport in the perovskite solid solution LaNi1-xCoxO3

We have studied the resistivity and thermopower of the solid solution LaNi1-xCoxO3 in the temperature range 1.4K-300K. Effect of interaction and localization are seen in the low temperature transport data for x<0.55. A negative anomaly in the thermopower has been observed at low temperature for 0.1

Nonlinear conduction and electrical switching in one-dimensional conductors

Many one-dimensional conductors show pronounced nonlinear electrical conduction. Some of them show very interesting electrical switching from a low conducting state to a high conducting state. Such electrical switching is often associated with memory. These are discussed with particular emphasis on charge transfer complexestmbine-tcnq, tmpd-tcnq, Cs2(tcnq)3,tea-(tcnq) 2 ando-tolidine-iodine.

Electrical properties of silver pyrophosphate glass

Electrical conductivities and dielectric properties of glassy Ag4P2O7 have been investigated as a function of temperature and frequency. The variation of the properties is consistent with the structure of this glass which consists of a variety of polymeric anion species. Upon crystallization Ag4P2O7 appears to retain some of the anionic species in the solid solution as evident from the phase transition behaviour at higher temperatures.

Electrical transport in layered crystalline semiconductors GeS doped with Ag, P impurities at high pressure

A study of the transport properties of layered crystalline semiconductors GeS (undoped and doped with Ag, P impurity) under quasihydrostatic pressure using Bridgman anvil system is made for the first time. Pressure-induced effects in undoped crystals reveal initial rise in resistivity followed by two broad peaks at higher pressures. Silver doping induces only minor changes in the behaviour except removing the second peak. Phosphorous impurity is found to have drastic effect on the transport properties. Temperature dependence of the resistivity exhibits two activation energies having opposite pressure coefficients. Results are discussed in the light of intrinsic features of the layered semiconductors.

A Huge Effect of Weak dc Electrical Fields on Grain Growth in Zirconia

We show that the application of a modest dc electrical field, about 4 V/cm, can significantly reduce grain growth in yttria-stabilized polycrystalline zirconia. These measurements were made by annealing samples, for 10 h at 1300°C, with and without an electrical field. The finding adds a new dimension to the role of applied electrical fields in sintering and superplasticity, phenomena that are critical to the net-shape processing of ceramics. Grain-growth retardation will considerably enhance the rates of sintering and superplasticity, leading to significant energy efficiencies in the processing of ceramics.

Non-Destructive Method to Estimate the Moisture Content in Bread using Multi-Channel Electrical Impedance Spectroscopy

Bread undergoes several physicochemical changes during storage that results in a rapid loss of freshness. These changes depend on moisture content present in bread product. An instrument based on electrical impedance spectroscopy technique is developed to estimate moisture content of bread at different zones using designed multi-channel ring electrodes. A dedicated AT89S52 microcontroller and associated peripherals are employed for hardware. A constant current is applied across bread loaf through central pair of electrodes and developed potential across different zones of bread loaf are measured using remaining four ring electrode pairs. These measured values of voltage and current are used to measure the impedance at each zone. Electrical impedance behavior of the bread loaf at crust and crumb is investigated during storage. A linear relationship is observed between the measured impedance and moisture content present in crust and crumb of bread loaf during storage of 120 hours.

Electrical conduction in plasma polymerized thin films of γ-terpinene

Plasma polymerized c-terpinene (pp2GT) thin films are fabricated using RF plasma polymerization. MIM structures are fabricated and using the capacitive structures dielectric properties of the material is studied. The dielectric constant values are found to be in good agreement with those determined from ellipsometric data. At a frequency of 100 kHz, the dielectric constant varies with RF deposition power, from 3.69 (10 W) to 3.24 (75 W). The current density–voltage (J2V) characteristics of pp–GT thin films are investigated as a function of RF deposition power at room temperature to determine the resistivity and DC conduction mechanism of the films. At higher applied voltage region, Schottky conduction is the dominant DC conduction mechanism. The capacitance and the loss tangent are found to be frequency dependent. The conductivity of the pp2GT thin films is found to decrease from 1.39 3 10212 S/cm (10 W) to 1.02 3 10213 S/cm (75 W) and attributed to the change in the chemical composition and structure of the polymer. The breakdown field for pp–GT thin films increases from 1.48 MV/cm (10 W) to 2 MV/cm (75 W). A single broad relaxation peak is observed indicating the contribution of multiple relaxations to the dielectric response for temperature dependent J2V. The distribution of these relaxation times is determined through regularization methods. VC 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42318.

A bottom-up integration of vision and actions to create cognitive humanoids

In recent years more and more complex humanoid robots have been developed. On the other hand programming these systems has become more difficult. There is a clear need for such robots to be able to adapt and perform certain tasks autonomously, or even learn by themselves how to act. An important issue to tackle is the closing of the sensorimotor loop. Especially when talking about humanoids the tight integration of perception with actions will allow for improved behaviours, embedding adaptation on the lower-level of the system.

A Modified Heffron-Phillip's Model for The Design of Power System Stabilizers

In this paper a modified Heffron-Phillip's (K-constant) model is derived for the design of power system stabilizers. A knowledge of external system parameters, such as equivalent infinite bus voltage and external impedances or their equivalent estimated values is required for designing a conventional power system stabilizer. In the proposed method, information available at the secondary bus of the step-up transformer is used to set up a modified Heffron-Phillip's (ModHP) model. The PSS design based on this model utilizes signals available within the generating station. The efficacy of the proposed design technique and the performance of the stabilizer has been evaluated over a range of operating and system conditions. The simulation results have shown that the performance of the proposed stabilizer is comparable to that could be obtained by conventional design but without the need for the estimation and computation of external system parameters. The proposed design is thus well suited for practical applications to power system stabilization, including possibly the multi-machine applications where accurate system information is not readily available.

Relaxation Labeling with Learning Automata

Relaxation labeling processes are a class of mechanisms that solve the problem of assigning labels to objects in a manner that is consistent with respect to some domain-specific constraints. We reformulate this using the model of a team of learning automata interacting with an environment or a high-level critic that gives noisy responses as to the consistency of a tentative labeling selected by the automata. This results in an iterative linear algorithm that is itself probabilistic. Using an explicit definition of consistency we give a complete analysis of this probabilistic relaxation process using weak convergence results for stochastic algorithms. Our model can accommodate a range of uncertainties in the compatibility functions. We prove a local convergence result and show that the point of convergence depends both on the initial labeling and the constraints. The algorithm is implementable in a highly parallel fashion.

Non-ohmic conduction and electrical switching under pressure of the charge transfer complexo-tolidine-iodine

The current voltage characteristics ofo-tolidine-iodine, with stoichiometry 1:1 grown from benzene, have been studied under high pressures upto 6 GPa atT=300 K andT=77 K. The characteristics show a pronounced deviation from ohmicity beyond a certain current for all pressures studied. At room temperature, beyond a threshold field the system switches from a low conductingOFF state to a high conductingON state with σON/σOFF ∼ 103. TheOFF state can be restored by the application of an a.c. pulse of low frequency. The temperature dependence of the two states studied indicates that theOFF state is semiconducting while theON state, beyond a certain applied pressure is metallic. The characteristics atT=77 K do not show any switching.