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Oscillating Behavior 2015

The oscillation of a function or a sequence quantifies the variance between its extreme values as it approaches infinity or a point. As such, oscillating behaviors are important to the Science of Security in terms of predictive metrics and resilience. The articles cited here were presented in 2015.

Gozse, I.; Soumelidis, A., "Realizing System Poles Identification on the Unit Disc Based on the Fourier Transform of Laguerre-Coefficients," in Control and Automation (MED), 2015 23th Mediterranean Conference on, pp. 821-826, 16-19 June 2015. doi: 10.1109/MED.2015.7158847

Abstract: This paper proposes a new method of identification of the poles in a discrete linear system from frequency domain data. The discrete rational transfer function is represented in a rational Laguerre basis, where the basis elements can be expressed by powers of the Blaschke-function. Laguerre coefficients are considered as a sum of oscillating signals what gives the opportunity to estimate the number and place of poles of the system by the Fourier trasform of the Laguerre-coefficients. The behavior of the method is analyzed in the presence of noise in the measurements and an example is presented as an illustration of the full procedure.

Keywords: Fourier transforms; signal processing; stochastic processes; transfer functions; Blaschke-function; Fourier transform; Laguerre-coefficients; discrete linear system; discrete rational transfer function; frequency domain data; rational Laguerre basis; system poles identification; unit disc; Discrete Fourier transforms; Frequency-domain analysis; Mathematical model; Noise; Noise measurement; Identification; Linear systems (ID#: 15-7904)


Zhenhui Li; Jingjing Wang; Jiawei Han, "ePeriodicity: Mining Event Periodicity from Incomplete Observations," in Knowledge and Data Engineering, IEEE Transactions on, vol. 27, no. 5, pp. 1219-1232, May 1 2015. doi: 10.1109/TKDE.2014.2365801

Abstract: Advanced technology in GPS and sensors enables us to track physical events, such as human movements and facility usage. Periodicity analysis from the recorded data is an important data mining task which provides useful insights into the physical events and enables us to report outliers and predict future behaviors. To mine periodicity in an event, we have to face real-world challenges of inherently complicated periodic behaviors and imperfect data collection problem. Specifically, the hidden temporal periodic behaviors could be oscillating and noisy, and the observations of the event could be incomplete. In this paper, we propose a novel probabilistic measure for periodicity and design a practical algorithm, ePeriodicity, to detect periods. Our method has thoroughly considered the uncertainties and noises in periodic behaviors and is provably robust to incomplete observations. Comprehensive experiments on both synthetic and real datasets demonstrate the effectiveness of our method.

Keywords: data mining; probability; GPS; data mining task; e-periodicity analysis; facility usage; hidden temporal periodic behaviors; human movements; imperfect data collection problem; incomplete observations; outlier detection; period detection; periodic behavior noises; periodic behavior prediction; periodic behavior uncertainties; periodicity event mining; periodicity mining; physical event tracking; physical events; probabilistic measure; real datasets; sensors; synthetic datasets; Global Positioning System; Markov processes; Nonhomogeneous media; Probabilistic logic; Random processes; Sensors; Vectors; Incomplete Observations; Periodicity; Probabilistic Model; incomplete observations; probabilistic model (ID#: 15-7905)


Jeon, J.P.; Hong, J.; Lee, Y.R.; Seo, J.H.; Oh, S.H.; Chung, S.K., "Novel Energy Harvesting Using Acoustically Oscillating Microbubbles," in Solid-State Sensors, Actuators and Microsystems (TRANSDUCERS), 2015 Transducers - 2015 18th International Conference on, pp. 1933-1936, 21-25 June 2015. doi: 10.1109/TRANSDUCERS.2015.7181330

Abstract: When a bubble hanging on a piezocantilever is excited by an acoustic wave around its resonant frequency, it oscillates and simultaneously generates cavitational microstreaming around it. The microstreaming bends the piezocantilever with fine vibration, resulting in electric power generation from the piezocantilever. In this study, we explore the dynamic behaviors of an acoustically oscillating bubble on the flexible substrate as well as demonstrate applicability of the proposed system to practical applications such as energy harvesting and acoustic wave sensors. First, the effects of an applied frequency and bubble size on the dynamic characteristics of an acoustically oscillating bubble, such as maximum amplitude and resonant frequency, are experimentally investigated. The amplitude of an oscillating bubble is maximized at its resonant frequency, which is inversely proportional to its size. In addition, electrical voltage generated by a piezocantilever attaching with an oscillating bubble is measured at different applied frequencies, bubble sizes, and distances between the bubble and piezoactuator. The results show that the generated voltage is strongly affected by the applied frequency and is inversely proportional to the bubble size and the distance between the bubble and piezoactuator. Finally, the output voltage is almost linearly proportional to the number of bubbles.

Keywords: bubbles; energy harvesting; microfluidics; piezoelectric actuators; acoustic wave sensors; acoustically oscillating microbubbles; cavitational microstreaming; electric power generation; energy harvesting; flexible substrate; piezoactuator; piezocantilever; resonant frequency; Acoustic waves; Energy harvesting; Microfluidics; Oscillators; Resonant frequency; Sensors; Bubble dynamics; acoustic wave sensors; cavitational microstreaming; energy harvesting (ID#: 15-7906)


Juanjuan Shi; Ming Liang, "Oscillatory Behavior Based Fault Feature Extraction for Bearing Fault Diagnosis," in Advanced Mechatronic Systems (ICAMechS), 2015 International Conference on, pp. 473-478, 22-24 Aug. 2015. doi: 10.1109/ICAMechS.2015.7287157

Abstract: An intelligent fault signature extraction scheme based on oscillatory behaviors is reported in this paper for bearing fault diagnosis. The proposed method is based on the joint application of morphological component analysis (MCA) and tunable Q-factor wavelet transform (TQWT) to decompose a signal into two signal components (i.e., low- and high-oscillation components) according to whether they having sustained oscillations. As bearing fault-induced transients (low-oscillation component) oscillate differently from periodic interferences and noise (high-oscillation component and residual), they can be separated via the MCA with the aid of TQWT which is parameterized by Q-factor and plays a role of distinguishing signal components presenting different oscillatory behaviors. The low- and high-oscillation components can be obtained by solving the objective function formulated based on MCA and TQWT. The determination of Q-factor for each signal component representation is also explored in this paper. The effectiveness of the proposed method is examined by experimental data.

Keywords: Q-factor; fault diagnosis; feature extraction; machine bearings; mechanical engineering computing; oscillations; signal processing; bearing fault diagnosis; bearing fault-induced transients; fault feature extraction; intelligent fault signature extraction; morphological component analysis; oscillatory behavior; periodic interferences; signal component representation; signal components; tunable Q-factor wavelet transform; Conferences; Decision support systems; Mechatronics; Bearing Fault Diagnosis; Intelligent Fault Feature Extraction; Oscillatory Behavior; Signal Decomposition; Tunable Q-factor Wavelet Transform (ID#: 15-7907)


Cai, W.; Yi, F.; Cosoroaba, E.; Fahimi, B., "Stability Optimization Method Based on Virtual Resistor and Nonunity Voltage Feedback Loop for Cascaded DC-DC Converters," in Industry Applications, IEEE Transactions on, vol. 51, no. 6, pp. 4575-4583, Nov.-Dec. 2015. doi: 10.1109/TIA.2015.2443717

Abstract: This paper proposes a stability optimization method based on virtual resistor and nonunity voltage feedback loop for cascaded dc-dc converters. Oscillating phenomenon or instability would occur occasionally with two or more closed-loop dc-dc converters in series. The virtual resistor and nonunity voltage feedback are used to modify the feedback loop instead of only a direct voltage feedback to improve stability and get rid of oscillating behavior. Based on the stability analysis of dc-dc converters with distributed parameters, several cases have been derived. After that, relative to different cases, two modified methods based on virtual resistor and nonunity voltage feedback loop are proposed to stabilize the overall system. With these methods, no extra power loss would be generated, and it is easy to embed them into any conventional control system. Experimental results verified the theoretical analysis and feasibility of the proposed control methods.

Keywords: Capacitors; DC-DC power converters; Feedback loop; Impedance; Inductors; Resistors; Stability analysis; Cascaded converter; constant power load; constant-power load (CPL); negative impedance; non-unity feedback; nonunity feedback; virtual resistor (ID#: 15-7908)


Senkal, D.; Efimovskaya, A.; Shkel, A.M., "Minimal Realization of Dynamically Balanced Lumped Mass WA Gyroscope: Dual Foucault Pendulum," in Inertial Sensors and Systems (ISISS), 2015 IEEE International Symposium on, pp. 1-2, 23-26 March 2015. doi: 10.1109/ISISS.2015.7102394

Abstract: We report a new type of MEMS rate integrating gyroscope. The Dual Foucault Pendulum (DFP) gyroscope consists of two dynamically equivalent, mechanically coupled proof masses, oscillating in anti-phase motion, creating a dynamically balanced resonator with x-y symmetry in frequency and damping. Phase synchronization is established by mechanical coupling of the two proof masses, whereas quadrature suppression is achieved by four differential shuttle pairs placed in-between. Dual axis tuning fork behavior provides vibration immunity and anchor loss mitigation, resulting in a Qfactor over 100,000 on both modes at a center frequency of 2.7 kHz. Whole angle mechanization is demonstrated by FPGAbased closed loop control of the gyroscope, showing a scale factor variation of 22 ppm RMS over 2 hours of measurement. We believe Dual Foucault Pendulum is the minimal realization of a dynamically balanced lumped mass whole angle (WA) gyroscope.

Keywords: angular measurement; closed loop systems; field programmable gate arrays; gyroscopes; mass measurement; microsensors; pendulums; synchronisation; vibration measurement; vibrations; DFP gyroscope; FPGA-based closed loop control; MEMS rate integrating gyroscope; anchor loss mitigation; antiphase motion; differential shuttle pair; dual axis tuning fork;dual foucault pendulum gyroscope; dynamically balanced lumped mass WA gyroscope; dynamically balanced resonator; frequency 2.7 kHz; mechanical coupled proof mass; phase synchronization; quadrature suppression; vibration immunity; whole angle gyroscope; whole angle mechanization; x-y symmetry; Couplings; Damping; Gain control; Gyroscopes; Micromechanical devices; Phase locked loops; Vibrations; Rate integrating MEMS gyroscope; closed loop control; tuning fork behaviour; whole angle mechanization (ID#: 15-7909)


Cossutta, P.; Aguirre, M.P.; Cao, A.; Raffo, S.; Valla, M.I., "A Novel Modulation Technique for Single Phase Current Source Inverters with Active Buffering," in Industrial Technology (ICIT), 2015 IEEE International Conference on, pp. 2036-2041, 17-19 March 2015. doi: 10.1109/ICIT.2015.7125396

Abstract: Interface between electric grids and renewable energy sources are of a big concern to researchers worldwide. Many efforts are applied to obtain converter topologies and modulation techniques with increasing features regarding switching behavior, input and output distortion, efficiency, switches utilization ratio and reliability. Interfacing constant power sources with sinusoidal systems require huge storage capabilities to compensate the oscillating output power. This storage implies higher costs, lower reliability and bulkier systems. In this paper a new modulation technique for a single phase Current Source Inverter (CSI) with an Active Buffer (AB) is presented. The AB allows to reduce the size and ripple requirements of the storage element, increasing reliability and improving overall performance.

Keywords: invertors; modulation; active buffering; constant power source interface; modulation technique; renewable energy source; ripple reduction; single phase current source inverter; size reduction; storage element; Capacitors; Inverters; Phase locked loops; Phase modulation; Power generation; Switches (ID#: 15-7910)


Choi, Y.; Lee, K.; Kim, Y.; Kim, T.; You, C.; Jung, M., "Oscillatory Magnetic Coupling in Amorphous CoSiB/Pt/CoSiB Structure," in Magnetics Conference (INTERMAG), 2015 IEEE, pp. 1-1, 11-15 May 2015.doi: 10.1109/INTMAG.2015.7156734

Abstract: This paper investigates the magnetic interaction between two CoSiB layers separated by a Pt layer. The CoSiB/Pt/CoSiB sandwich structures are grown using DC sputtering method. Anomalous Hall effect is measured at room temperature. The magnitudes of Hall voltage signals are oscillating as a function of the Pt thickness, resembling the oscillatory behavior observed for the Ruderman-Kittle-Kasuya-Yosida (RKKY) interaction. For 22 and 27 A thickness, clear signals from the antiferromagnetic coupling have been seen in both AHE and magnetization data. In order to exploit the mechanism of indirect interlayer coupling, the AHE is also measured as a function of perpendicular field Hz in an external magnetic field of Hx or Hy parallel to the film plane. AHE results show a shift of hysteresis loop, similar to an exchange bias effect found in ferromagnetic/antiferromagnetic bilayer structure. This behavior is analyzed using the Stoner-Wohlfarth model.

Keywords: Hall effect; RKKY interaction; amorphous magnetic materials; antiferromagnetic materials; boron alloys; cobalt alloys; magnetic hysteresis; magnetic multilayers; platinum; sandwich structures; silicon alloys; sputter deposition; CoSiB-Pt-CoSiB; DC sputtering; Hall voltage signals; Ruderman-Kittle-Kasuya-Yosida interaction; Stoner-Wohlfarth model; amorphous structure; anomalous Hall effect; antiferromagnetic coupling; exchange bias effect; external magnetic field; ferromagnetic-antiferromagnetic bilayer structure; hysteresis loop; indirect interlayer coupling; magnetic interaction; magnetization; oscillatory magnetic coupling; perpendicular field; sandwich structures; temperature 293 K to 298 K; Amorphous magnetic materials; Magnetic domain walls; Magnetic domains; Magnetic hysteresis; Magnetic multilayers; Magnetic separation; Perpendicular magnetic anisotropy (ID#: 15-7911)


Bin Sayed, S.; Ulku, H.A.; Bagci, H., "A Stable Marching On-In-Time Scheme for Solving the Time-Domain Electric Field Volume Integral Equation on High-Contrast Scatterers," in Antennas and Propagation, IEEE Transactions on, vol. 63, no. 7, pp. 3098-3110, July 2015. doi: 10.1109/TAP.2015.2429736

Abstract: A time-domain electric field volume integral equation (TD-EFVIE) solver is proposed for characterizing transient electromagnetic wave interactions on high-contrast dielectric scatterers. The TD-EFVIE is discretized using the Schaubert-Wilton-Glisson (SWG) and approximate prolate spherical wave (APSW) functions in space and time, respectively. The resulting system of equations cannot be solved by a straightforward application of the marching on-in-time (MOT) scheme since the two-sided APSW interpolation functions require the knowledge of unknown "future" field samples during time marching. Causality of the MOT scheme is restored using an extrapolation technique that predicts the future samples from known "past" ones. Unlike the extrapolation techniques developed for MOT schemes that are used in solving time-domain surface integral equations, this scheme trains the extrapolation coefficients using samples of exponentials with exponents on the complex frequency plane. This increases the stability of the MOT-TD-EFVIE solver significantly, since the temporal behavior of decaying and oscillating electromagnetic modes induced inside the scatterers is very accurately taken into account by this new extrapolation scheme. Numerical results demonstrate that the proposed MOT solver maintains its stability even when applied to analyzing wave interactions on high-contrast scatterers.

Keywords: approximation theory; electric field integral equations; electromagnetic wave scattering; extrapolation; interpolation; stability; time-domain analysis; MOT-TD-EFVIE solver; SWG scheme; Schaubert-Wilton-Glisson scheme; approximate prolate spherical wave function; extrapolation technique; high-contrast dielectric scatterer; stability; stable marching on-in-time scheme; time-domain electric field volume integral equation; time-domain surface integral equation; transient electromagnetic wave interaction; two-sided APSW interpolation function;Accuracy;Convolution;Dielectrics;Extrapolation;Integral equations; Numerical stability; Time-domain analysis; Band-limited interpolation; Marching on-in-time method; band-limited interpolation; electric field volume integral equation; electric field volume integral equation (EFVIE); extrapolation; marching on-in-time (MOT) method; time domain analysis; time-domain analysis; transient analysis (ID#: 15-7912)


O'Riordan, E.; Dudka, A.; Galayko, D.; Basset, P.; Feely, O.; Blokhina, E., "Capacitive Energy Conversion With Circuits Implementing a Rectangular Charge-Voltage Cycle Part 2: Electromechanical and Nonlinear Analysis," in Circuits and Systems I: Regular Papers, IEEE Transactions on, vol. 62, no. 11, pp. 2664-2673, Nov. 2015. doi: 10.1109/TCSI.2015.2451913

Abstract: In this paper, we explore and describe the electromechanical coupling which results from eKEH conditioning circuits implementing a rectangular QV cycle, including but not limited to the charge pump and Bennet's doubler circuits. We present numerical and semi-analytical analyses describing the nonlinear relationship between the oscillating mass and the conditioning circuit. We believe this is a poorly understood facet of the device and, as we will portray, affects the potential harvested energy. An approach to determine the frequency shift due to the electromechanical coupling is presented and compared with novel experimental results. We provide some examples of bifurcation behavior and show that the only source of nonlinearity is in the coupling between the electrical and mechanical domains. This work continues from the electrical analysis presented in Part 1, providing a full insight into the complex behavior of the electromechanical coupling.

Keywords: bifurcation; charge pump circuits; energy harvesting; frequency multipliers; signal conditioning circuits; Bennet doubler circuit; bifurcation behavior; capacitive energy conversion; charge pump; eKEH conditioning circuit; electromechanical analysis; electromechanical coupling; electrostatic kinetic energy harvester; frequency shift; nonlinear analysis; rectangular QV cycle; rectangular charge-voltage cycle; Force; Integrated circuit modeling; Mathematical model; Numerical models; Oscillators; Transducers; Vibrations; Bifurcation analysis; electromechanical coupling; electrostatic kinetic energy harvesters; multiple scale methods; steady-state oscillations (ID#: 15-7913)


Ramirez, D.; Bartolome, J.P.; Martinez, S.; Herrero, L.C.; Blanco, M., "Emulation of an OWC Ocean Energy Plant With PMSG and Irregular Wave Model," in Sustainable Energy, IEEE Transactions on, vol. 6, no. 4, pp. 1515-1523, Oct. 2015. doi: 10.1109/TSTE.2015.2455333

Abstract: Ocean energy is a promising resource for renewable electricity generation that presents many advantages, such as being more predictable than wind energy, but also some disadvantages such as large and slow amplitude variations in the generated power. This paper presents a hardware-in-the-loop prototype that allows the study of the electric power profile generated by a wave power plant based on the oscillating water column (OWC) principle. In particular, it facilitates the development of new solutions to improve the intermittent profile of the power fed into the grid or the test of the OWC behavior when facing a voltage dip. Also, to obtain a more realistic model behavior, statistical models of real waves have been implemented.

Keywords: hydroelectric power stations; statistical analysis; wave power plants; OWC ocean energy plant; PMSG; electric power profile; generated power; hardware-in-the-loop prototype; irregular wave model; oscillating water column; renewable electricity generation; slow amplitude variations; statistical models; voltage dip; wave power plant; wind energy; Mathematical model; Prototypes; Renewable energy sources; Torque; Wave energy; Oscillating water column (OWC);renewable energy; ride through; wave energy (ID#: 15-7914)


Dietmannsberger, M.; Schulz, D., "Ancillary Services and Dynamic Behavior of Inverters Connected to the Low Voltage Grid," in Compatibility and Power Electronics (CPE), 2015 9th International Conference on, pp. 49-56, 24-26 June 2015. doi: 10.1109/CPE.2015.7231048

Abstract: Small generators connected to the low voltage grid must be able to provide ancillary services in order to support system stability nowadays and in the future. Grid codes have been implemented that demand for load-frequency control and reactive power control. Together with anti-islanding-detection, these control algorithms mainly affect the dynamic behavior of the inverters in case of loss of mains. In this paper, an inverter model is presented that complies with the major grid codes. Islanding tests show new effects that arise because of the interaction between different control algorithms. Oscillating operating points may occur under special circumstances. This leads to further investigations on frequency dynamics. The additional benefit of rate-of-change-of-frequency (ROCOF) monitoring is numbered in a quantitative analysis and simulation. Not only steady state, but dynamic behavior is investigated with respect to the Non-Detection-Zone (NDZ). It is shown, that using frequency dynamics, scales down NDZs of passive anti-islanding methods significantly.

Keywords: distributed power generation; frequency control; invertors; load regulation; power distribution faults; power grids; power system stability; reactive power control; NDZ; ROCOF monitoring; ancillary service; antiislanding detection; frequency dynamic; inverter dynamic behavior; load-frequency control; low voltage grid code; nondetection zone; quantitative analysis; rate-of-change-of-frequency monitoring; reactive power control; Generators; Inverters; Low voltage; Reactive power; Resonant frequency; Standards; Non Detection Zone; ROCOF; ancillary services; anti-islanding; inverter control; mains monitoring; rate of change of frequency (ID#: 15-7915)


Yang, J.; Yu, Q.; Zhao, J.; Qiu, J.; Wen, Y.; Li, P., "A Broadband and Two-Dimensional Vibration Energy Harvester using Multiple Magnetostrictive/Piezoelectric Composite Transducers," in Magnetics Conference (INTERMAG), 2015 IEEE, pp. 1-1, 11-15 May 2015. doi: 10.1109/INTMAG.2015.7156828

Abstract: There is growing interest in energy scavenging from natural vibration sources to power autonomous wireless telemetry devices. Vibration energy is typically converted into electrical energy using piezoelectric, electromagnetic, or electrostatic transduction mechanisms [1]. Despite the transduction mechanisms and novel structures, there is still an obstacle facing realistic implementation in most of the vibration-based energy harvester, because they are deigned to harvest energy in a single direction of the ambient vibrations. But a vibration source in real environment may exhibit several motion directions over time. Hence, they may not generate power effectively in the case of a motion with multiple or time-variant motion directions. To address this issue, Moss et al. proposed a bi-axial oscillator to extract vibration energy with arbitrary motion directions in a plane [2]. However, the AISI 52100 ball oscillating on the surface of the Terfenol-D will damage the transducer inevitably, and the bandwidth of the harvester was narrow (about 1 Hz). Magnetoelectric (ME) transducers (composed of magnetostrictive/ piezoelectric laminate composites) were originally intended for magnetic field sensors but have recently been used in vibration energy harvesting. Therefore, we report on a design for an energy harvester using ME transducers, in which only one vibrating body is used to extract the ambient vibration energy with arbitrary in-plane motion directions, and the frequency bandwidth can be enhanced by nonlinear behavior of the magnetic force.

Keywords: composite materials; energy harvesting; magnetostrictive devices; piezoelectric transducers; vibrations; ambient vibration energy; arbitrary in-plane motion directions; broadband vibration energy harvester; design; frequency bandwidth; magnetic force; multiple magnetostrictive/piezoelectric composite transducers; nonlinear behavior; two-dimensional vibration energy harvester; vibrating body; Energy harvesting; Magnetic circuits; Magnetic flux; Magnetoelectric effects; Magnetostriction; Transducers; Vibrations (ID#: 15-7916)


Huang, Z.; Yue, J.; Wang, J.; Zhai, Y.; Xu, Y.; Wang, B., "Oscillatory Tunneling Magnetoresistance in Fe3O4/GaAs/Fe3O4 Junction," in Magnetics Conference (INTERMAG), 2015 IEEE, pp. 1-1, 11-15 May 2015. doi: 10.1109/INTMAG.2015.7156969

Abstract: Spintronics strives to revolutionize conventional electronics by integrating magnetic materials with semiconductor devices, such as the spin field effect transistor (SFET), which not only improve the capabilities of electronic devices, but develop new functionalities. For electrodes of spin injection and detection in SFET device, half metallic Fe3O4 is an attractive candidate because its high Curie temperature of 858 K, large spin polarization near 100% at the Fermi level and relatively high electronic conductivity at room temperature, which is believed to benefit the injection of spin carriers into the semiconductors. For ferromagnetic metal(FM)/Semiconductor system, Fe3O4/GaAs is a very promising system for the fabrication of magnetoelectronic devices due to the Schottky contact of the Fe3O4/GaAs interface, which is crucial for studying the behaviors of spin dependent transportation for the devices. It is reported that in a FM/I/NM/I/FM double tunnel junction, where NM is the normal metal, and I the insulating barrier, theories predicted an oscillation of the tunneling magnetoresistance (TMR) effect as a function of the NM layer thickness because the spin polarization of the tunneling electron oscillates as a result of the resonant tunneling. Furthermore, Quantum oscillation of spin polarization in GaAs channel was experimentally demonstrated. In this paper, we have presented a theoretical approach to the tunneling conductance and TMR in a Fe3O4/GaAs/Fe3O4 magnetic double tunnel junction with both ballistic and diffusive components.

Keywords: III-V semiconductors; gallium arsenide; interface magnetism; iron compounds; oscillations; spin polarised transport; tunnelling magnetoresistance; Curie temperature; Fe3O4-GaAs-Fe3O4; Fermi level; GaAs channel; Schottky contact; ballistic component; detection electrode; diffusive component; electronic conductivity ;ferromagnetic metal-semiconductor system; insulating barrier; magnetic double tunnel junction; magnetic materials; magnetoelectronic device fabrication; quantum oscillation; resonant tunneling; semiconductor devices; spin carrier injection; spin dependent transportation; spin field effect transistor device; spin injection electrode; spin polarization; spintronics; tunneling conductance; tunneling electron; tunneling magnetoresistance effect oscillation; Frequency modulation; Gallium arsenide; Junctions; Magnetoelectronics; Oscillators; Tunneling magnetoresistance (ID#: 15-7917)


Gustavsen, B.; Runde, M.; Ohnstad, T.M., "Wideband Modeling, Field Measurement, and Simulation of a 420-kV Variable Shunt Reactor," in Power Delivery, IEEE Transactions on, vol. 30, no. 3, pp. 1594-1601, June 2015. doi: 10.1109/TPWRD.2014.2375556

Abstract: A 420-kV gapped-core five-legged variable shunt reactor is modeled in the frequency range 5 Hz-10 MHz based on frequency sweep measurements and curve fitting using rational functions. Comparison with time-domain measurements at reduced voltage shows that the model can accurately predict the transient behavior of the shunt reactor, both for impinging overvoltages and circuit-breaker transient recovery voltages. Among the observations is that mutual coupling between the phases leads to a beat phenomenon in the reactor voltage following disconnection. Representing the shunt reactor by an LC parallel circuit leads to unrealistic results for steep-fronted incoming waves and high-frequency oscillating overvoltages, and for the attenuation of the transient recovery voltage following disconnection.

Keywords: curve fitting; frequency measurement; overvoltage protection; rational functions; transients; circuit-breaker transient recovery voltages; curve fitting; field measurement; frequency sweep measurements; oscillating overvoltages; rational functions; transient behavior; variable shunt reactor; voltage 420 kV; wideband modeling; Current measurement; Frequency measurement; Inductors; Integrated circuit modeling; Shunts (electrical);Transient analysis; Voltage measurement; Black-box model; Electromagnetic Transients Program (EMTP); frequency dependency; simulation; transient recovery voltage; transients; variable shunt reactor (ID#: 15-7918)


Li, J.X.; Jia, M.W.; Sun, L.; Ding, Z.; Chen, B.L.; Wu, Y.Z., "Oscillatory Anisotropic Magnetoresistance Arising From Quantum Well States in Au/Fe(001) Bilayers," in Magnetics Letters, IEEE, vol. 6, pp.1-4, 2015. doi: 10.1109/LMAG.2015.2444831

Abstract: The anisotropic magnetoresistance (AMR) in epitaxial Au/Fe(001) bilayers grown on MgO(001) substrate was systematically studied as a function of Au thickness over the temperature range 6300K. The AMR oscillates with a period of about 1.8 nm in Au thickness at low temperatures and also oscillates at certain higher temperatures. Such novel oscillatory AMR behavior is attributed to quantum well states in Au ultrathin films.

Keywords: enhanced magnetoresistance; gold; iron; magnetic multilayers; quantum wells; Au-Fe; bilayers; oscillatory AMR behavior; oscillatory anisotropic magnetoresistance; quantum well states; temperature 6 K to 300 K; Films; Gold; Iron; Oscillators; Perpendicular magnetic anisotropy; Substrates; Magnetic and Spintronic Materials; Magnetic films; Magneto-Electronics; Magneto-electronics; Magnetoresistance; Spin Electronics; Thin films; magnetic and spintronic materials; magnetic films; magnetoresistance; spin electronics; thin films (ID#: 15-7919)


Taucer, M.; Karim, F.; Walus, K.; Wolkow, R.A., "Consequences of Many-Cell Correlations in Clocked Quantum-Dot Cellular Automata," in Nanotechnology, IEEE Transactions on, vol. 14, no. 4, pp. 638-647, July 2015. doi: 10.1109/TNANO.2015.2426058

Abstract: Quantum-dot cellular automata (QCA) provides a basis for classical computation without transistors. Many simulations of QCA rely upon the so-called intercellular Hartree approximation (ICHA), which neglects the possibility of entanglement between cells. The ICHA was originally proposed as a solution to the problem of exponential scaling in the computational cost of fully quantum mechanical treatments. However, in some cases, the ICHA predicted errors in QCA operation, and quantum correlations were required for circuits to operate correctly. While quantum correlations can remedy certain problems that present themselves in ICHA calculations, here we present simulations that show that quantum correlations may in fact be problematic in other situations, such as clocked QCA. Small groups of QCA cells are modelled with a Hamiltonian analogous to a quantum mechanical Ising-like spin chain in a transverse field, including the effects of intercellular entanglement completely. When energy relaxation is included in the model, we find that intercellular entanglement changes the qualitative behavior of the system, and new features appear. In clocked QCA, isolated groups of active cells have a tendency to oscillate between polarization states as information propagates. Additionally, energy relaxation tends to bring groups of cells to an unpolarized steady state. This contrasts with the results of previous simulations, which employed the ICHA. The ICHA may in fact be a good approximation in the limit of very low tunneling rates, which can be realized in lithographically defined quantum dots. However, in molecular and atomic implementations of QCA, entanglement will play a greater role. The degree to which intercellular correlations pose a problem for memory, and clocking depends upon implementation-specific details of the interaction of the system with its environment, as well as the system's internal dynamics.

Keywords: Ising model; SCF calculations; cellular automata; quantum computing; quantum dots; quantum entanglement; spin systems; Hamiltonian model; clocked quantum-dot cellular automata; energy relaxation; exponential scaling; intercellular Hartree approximation; intercellular entanglement; internal dynamics; many-cell correlations; polarization states; quantum computation; quantum correlations; quantum mechanical Ising-like spin chain; transverse field; tunneling rates; Approximation methods; Clocks; Correlation; Mathematical model; Quantum dots; Quantum mechanics; Steady-state; Nanoscale Devices; Nanoscale devices; Quantum Cellular Automata; Quantum Dots; quantum cellular automata; quantum dots (ID#: 15-7920)


Teixeira, F.P.P.; Shanahan, M., "Local and Global Criticality within Oscillating Networks of Spiking Neurons," in Neural Networks (IJCNN), 2015 International Joint Conference on, pp. 1-7, 12-17 July 2015. doi: 10.1109/IJCNN.2015.7280561

Abstract: Neuronal avalanches are a local cortical phenomenon characterised by bursts of activity bracketed by periods of quiescence. It has been shown both in vivo and in vitro that these avalanches exhibit features of systems within a critical state. Locally critical system's avalanches conform to power law-like distributions. Globally these systems consist of modules exhibiting long-range temporal correlations identifiable via Detrended Fluctuation Analysis (DFA). Using an eight module oscillatory spiking neural network we analyse the correlation between these local and global criticality markers. Our findings demonstrate that locally critical modules promote long-range temporal correlations. Furthermore, when local modules are no longer critical we find that modules become uncorrelated or noisy. This suggests a strong link between local and global critical behaviour.

Keywords: correlation theory; graph theory;network theory (graphs); neural nets; statistical distributions; stochastic processes; DFA; criticality marker; detrended fluctuation analysis; network oscillation; neuronal avalanche; power law-like distribution; spiking neural network; temporal correlation (ID#: 15-7921)



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