Reverse heat flow with Peltier-induced thermoinductive effect

The concept of “thermal inductance” expands the options of thermal circuits design. However, the inductive component is the only missing components in thermal circuits unlike their electromagnetic counterparts. Herein, we report an electrically controllable reverse heat flow, in which heat flows from a low-temperature side to a high-temperature side locally and temporarily in a single material by imposing thermal inertia and ac current. This effect can be regarded as an equivalent of the “thermoinductive” effect induced by the Peltier effect. We derive the exact solution indicating that this reverse heat flow occurs universally in solid-state systems, and that it is considerably enhanced by thermoelectric properties. A local cooling of 25 mK is demonstrated in (Bi,Sb)2Te3, which is explained by our exact solution. This effect can be directly applicable to the potential fabrication of “thermoinductor” in thermal circuits.

Design Methodology for Interfacing DERs to Power Systems through VSC

This paper presents a methodology to connect distributed energy resources via an 84-pulse voltage source converter to three-phase system grid or load of standard or nonstandard voltage values. Transfer function blocks are included to illustrate interfacing among converters. The main input-output values to be considered in the application are detailed and the system can be modified to be included in other systems without loss of generality. The definition of the reactive component for supporting grid or load variations without degrading the overall performance is carried by for the DC-DC converter. A control variable for reducing the DC gain is used to improve the settling time. Our proposal defines the capacitive and inductive component values for an operating point and gives the option to reduce them when adding smoothed variations and adaptive controllers.

Supercapacitance and superinductance of TiN and NbTiN films in the vicinity of superconductor-to-insulator transition

We investigate the low-temperature complex impedance of disordered insulating thin TiN and NbTiN films in the frequency region 400 Hz–1 MHz in close proximity to the superconductor–insulator transition (SIT). The frequency, temperature, and magnetic field dependencies of the real and imaginary parts of the impedance indicate that in full accord with the theoretical predictions and earlier observations, the films acquire self-induced electronic granularity and become effectively random arrays of superconducting granules coupled via Josephson links. Accordingly, the inductive component of the response is due to superconducting droplets, while the capacitive component results from the effective Josephson junctions capacitances. The impedance crosses over from capacitive to inductive behavior as films go across the transition.

Reverse Heat Flow with Peltier-Induced Thermoinductive Effect

The inductive component is the only missing components in thermal circuits unlike their electromagnetic counterparts. Herein, we report an electrically controllable reverse heat flow, which can be regarded as a proper equivalent of the “thermoinductive” effect. The underlying concept is the heating and cooling of the ends of the material by the Peltier effect under an applied ac current; this form a negative temperature gradient in the opposite direction in a controllable manner. We have derived the exact solution indicating that this reverse heat flow occurs universally in solid-state systems, even in conventional metallic Cu, and that it is considerably enhanced by thermoelectric properties (i.e., a large Seebeck coefficient and low thermal conductivity). A local cooling of 25 mK was demonstrated in (Bi,Sb)2Te3, which was explained by our exact solution. This electrically controlled reverse heat flow is directly applicable to the fabrication of a “thermoinductor” in thermal circuits.

Electromagnetic full- gyrokinetics in the tokamak edge with discontinuous Galerkin methods

We present an energy-conserving discontinuous Galerkin scheme for the full- $f$ electromagnetic gyrokinetic system in the long-wavelength limit. We use the symplectic formulation and solve directly for $\unicode[STIX]{x2202}A_{\Vert }/\unicode[STIX]{x2202}t$ , the inductive component of the parallel electric field, using a generalized Ohm’s law derived directly from the gyrokinetic equation. Linear benchmarks are performed to verify the implementation and show that the scheme avoids the Ampère cancellation problem. We perform a nonlinear electromagnetic simulation in a helical open-field-line system as a rough model of the tokamak scrape-off layer using parameters from the National Spherical Torus Experiment (NSTX). This is the first published nonlinear electromagnetic gyrokinetic simulation on open field lines. Comparisons are made to a corresponding electrostatic simulation.

Decoupling between causal understanding and awareness during learning and inference

Causal reasoning is a principal higher-cognitive ability of humans, however, much remains unknown, including (a) the type (systematic versus intermixed) and order (inductive-then-deductive or vice versa) of experience that best achieves causal-chain extraction; (b) how inferences generalize to novel problems, especially with one-shot experience; and (c) how metacognition, reflected in uncertainty of one’s knowledge, relates to actual knowledge. We tested people on a realistic cancer biology task (e.g., ‘seroc’ chemicals inducing tumors with subsequent effects). Systematic experience was superior, with some evidence that the inductive-then-deductive order promoted stronger one-shot generalization. Notably, uncertainty was decoupled from actual knowledge, with the deductive-then-inductive group being overconfident, likely reflecting lack of awareness of the inductive component; while those with successful one-shot generalization held lower confidence, reflecting generalization with minimal experience, while remaining skeptical. Our findings clarify processes underlying causal reasoning, and reveal a complex relationship between causal reasoning and metacognitive awareness of it.

A Transformer Class E Amplifier

In a high-efficiency Class E ZVS resonant amplifier a matching and isolation transformer can replace some or even all inductive components of the amplifier thus simplifying the circuit and reducing its cost. In the paper a theoretical analysis, a design example and its experimental verification for a transformer Class E amplifier are presented. In the experimental amplifier with a transformer as the only inductive component in the circuit high efficiency ηMAX = 0.95 was achieved for supply voltage VI = 36 V, maximum output power POMAX = 100 W and the switching frequency f = 300 kHz. Measured parameters and waveforms showed a good agreement with theoretical predictions. Moreover, the relative bandwidth of the switching frequency was only 19% to obtain output power control from 4.8 W to POMAX with efficiency not less than 0.9 in the regulation range.

Plasma Impedance Tuning Effect on Nanostructure of Diamond Films

The morphology and structure of nanocrystalline diamond films as well as the plasma chemistry were studied by altering the plasma impedance. These impedances related to electron density were altered via the matching system. Two films were grown by the microwave plasma under different values of the plasma impedance, resulting in low and high electron densities in the plasma. By the use of measurements of plasma impedance and optical emission, the lowering of an inductive component of the impedance, indicating an increasing electron density, encouraged H-radical concentration present in the plasma. As the plasma was changed to the high electron density, Raman spectra of the films showed the sp3Raman peak shifted from 1325 to 1328.5 cm-1with narrower broadening. This behavior arose from an increase in grain size, corresponding to images from a field emission scanning electron microscope. Raman spectra of G-peak position and white light reflectometry showed a reduction in sp2carbon content of the film. The G-peak shifted from 1564 to 1541 cm-1and refractive index increased from 1.84 to 2.16. The formation of the films related to the concentrations of H and CH3radicals. The plasma impedance affected the radical concentrations.