Non-isolated System Research Articles

Noninvasive Quantum Measurement of Arbitrary Operator Order by Engineered Non-Markovian Detectors.

The development of solid-state quantum technologies requires the understanding of quantum measurements in interacting, nonisolated quantum systems. In general, a permanent coupling of detectors to a quantum system leads to memory effects that have to be taken into account in interpreting the measurement results. We analyze a generic setup of two detectors coupled to a quantum system and derive a compact formula in the weak-measurement limit that interpolates between an instantaneous (text-book type) and almost continuous-detector dynamics-dependent-measurement. A quantum memory effect that we term "system-mediated detector-detector interaction" is crucial to observe noncommuting observables simultaneously. Finally, we propose a mesoscopic double-dot detector setup in which the memory effect is tunable and that can be used to explore the transition to non-Markovian quantum measurements experimentally.

A Comparison of Non-Isolated High-Gain Three-Port Converters for Hybrid Energy Storage Systems

This work carries out a comparison of non-isolated topologies for power electronic converters applied to Hybrid Energy Storage Systems. At the considered application, several options for three-port circuits are evaluated when interfacing a DC link with two distinct electrical energy storage units. This work demonstrates how the proposed structure, referred to as Series-Parallel Connection, performs as a simple, compact and reliable approach, based on a modification of the H-bridge configuration. The main advantage of this solution is that an effective large voltage gain at one of the ports is attained by means of a simple topology, preventing the use of multilevel or galvanic-isolated power stages. The resulting structure is thoroughly compared against the most significant direct alternatives. The analysis carried out on the switching and conduction losses in the power switches of the target solution states the design constraints at which this solution shows a performance improvement. The experimental validations carried out on a 10 kW prototype demonstrate the feasibility of the proposed scheme, stating its benefits as well as its main limitations. As a conclusion, the Series-Parallel Connection shows a better performance in terms of efficiency, reliability and controllability in the target application of compensating grid or load variations in Non-Isolated Hybrid Storage Systems, with large mismatch in the storage device voltage ratings.

Neutral Point Clamped MOSFET Inverter With Full-Bridge Configuration for Nonisolated Grid-Tied Photovoltaic System

Existing nonisolated full-bridge neutral point clamped (NPC) inverters for a single-phase grid-tied photovoltaic (PV) system have limitations such as shoot-through and low European Union (EU) efficiency. In order to address these limitations, an NPC superjunction MOSFET nonisolated inverter with full-bridge configuration (NIIFBC) is proposed in this paper. This inverter reduces the possibility of shoot-through, thereby improving the reliability of the grid-tied PV system. It controls the grid current by energizing two coupled inductors individually during positive and negative half-grid cycles. This obviates the possibility of reverse recovery loss in switches due to their body diodes. Furthermore, two external silicon carbide diodes of a clamping branch cause negligible reverse recovery loss in switches besides a constant common-mode voltage. Therefore, the main claims of NIIFBC are low leakage current, high EU efficiency, and reliability. A generalized leakage current model for the proposed inverter is developed. In order to validate the veracity of the model and the claims of NIIFBC, a 1-kW prototype is designed and developed. The experimental results of NIIFBC validate the claims made by the authors. Its performance comparison with the existing nonisolated full-bridge inverters is given. Furthermore, a variant circuit of NIIFBC operating at nonunity power factor is proposed.

An Online Transformerless Uninterruptible Power Supply (UPS) System With a Smaller Battery Bank for Low-Power Applications

Uninterruptible power supplies (UPS) are widely used to provide reliable and high-quality power to critical loads in all grid conditions. This paper proposes a nonisolated online UPS system. The proposed system consists of bridgeless PFC boost rectifier, battery charger/discharger, and an inverter. A new battery charger/discharger has been implemented which ensures the bidirectional flow of power between dc link and battery bank, reducing the battery bank voltage to only 24V, and regulates the dc-link voltage during the battery power mode. Operating batteries in parallel improves the battery performance and resolve the problems related to conventional battery banks that arrange batteries in series. A new control method, integrating slide mode and proportional-resonant control, for the inverter has been proposed which regulates the output voltage for both linear and nonlinear loads. The controller exhibits excellent performance during transients and step changes in load. The operating principle and experimental results of 1-kVA prototype have been presented for validation of the proposed system.

Kinetic corrections from analytic non-Maxwellian distribution functions in magnetized plasmas

In magnetized plasma physics, almost all developed analytic theories assume a Maxwellian distribution function (MDF) and in some cases small deviations are described using the perturbation theory. The deviations with respect to the Maxwellian equilibrium, called kinetic effects, are required to be taken into account especially for fusion reactor plasmas. Generally, because the perturbation theory is not consistent with observed steady-state non-Maxwellians, these kinetic effects are numerically evaluated by very central processing unit (CPU)-expensive codes, avoiding the analytic complexity of velocity phase space integrals. We develop here a new method based on analytic non-Maxwellian distribution functions constructed from non-orthogonal basis sets in order to (i) use as few parameters as possible, (ii) increase the efficiency to model numerical and experimental non-Maxwellians, (iii) help to understand unsolved problems such as diagnostics discrepancies from the physical interpretation of the parameters, and (iv) obtain analytic corrections due to kinetic effects given by a small number of terms and removing the numerical error of the evaluation of velocity phase space integrals. This work does not attempt to derive new physical effects even if it could be possible to discover one from the better understandings of some unsolved problems, but here we focus on the analytic prediction of kinetic corrections from analytic non-Maxwellians. As applications, examples of analytic kinetic corrections are shown for the secondary electron emission, the Langmuir probe characteristic curve, and the entropy. This is done by using three analytic representations of the distribution function: the Kappa distribution function, the bi-modal or a new interpreted non-Maxwellian distribution function (INMDF). The existence of INMDFs is proved by new understandings of the experimental discrepancy of the measured electron temperature between two diagnostics in JET. As main results, it is shown that (i) the empirical formula for the secondary electron emission is not consistent with a MDF due to the presence of super-thermal particles, (ii) the super-thermal particles can replace a diffusion parameter in the Langmuir probe current formula, and (iii) the entropy can explicitly decrease in presence of sources only for the introduced INMDF without violating the second law of thermodynamics. Moreover, the first order entropy of an infinite number of super-thermal tails stays the same as the entropy of a MDF. The latter demystifies the Maxwell's demon by statistically describing non-isolated systems.

Seismic behavior characteristic of high damping rubber bearing through shaking table test

We investigated a high damping rubber bearing (HDRB) that mitigates damage to buildings and bridges from earthquakes. An HDRB can bear large loads for long periods of time and is capable of large deformations during an earthquake. The characteristics of the HDRB considered in this research include a very high damping capacity, with an equivalent damping factor of more than 15 % for a large earthquake. Moreover, we examined various dependency properties such as compressive stress, frequency, and repeated loading. To evaluate seismic isolation with an HDRB on several earthquake waves, we performed a shaking table test. In this test, deck acceleration was measured by accelerometers. Shear forces on piers were surveyed by using load cells. Furthermore, the seismic capacity of an isolated system with an HDRB was compared with a non-isolated system through shaking table tests. The results show that deck acceleration and shear force were relatively reduced by the HDRB.

Fractional electron number, temperature, and perturbations in chemical reactions.

We provide a perspective on the role of non-integer electron number in the density functional theory approach to chemical reactivity (conceptual DFT), emphasizing that it is important to not only treat reagents as open systems, but also as non-isolated systems, in contact with their surroundings. The special case of well-separated reagents is treated in some detail, as is the case where reagents interact strongly. The resulting expressions for the chemical potential of an acid, μacid = -(αI + A)/(1 + α), and a base, μbase = -(I + αA)/(1 + α), elucidate and generalize the assumptions inherent in the chemical potential models of Mulliken (α = 1) and Gazquez, Cedillo, and Vela (α = 3). In the strongly-interacting limit, it is appropriate to model the effects of the environment as a state-specific effective temperature, thereby providing a rigorous justification for the phenomenological effective-temperature model one of the authors previously proposed. The framework for the strongly interacting limit subsumes our model for weakly-interacting subsystems at nonzero temperature, the case of open but otherwise noninteracting subsystems, and the zero-temperature limit.

Causal non-locality can arise from constrained replication

The fundamental theories of physics are local theories, depending on local interactions of local variables. It is not clear if and how strictly local theories can produce non-local variables that have causal effectiveness. Yet, non-local effectiveness appears to exist, such as in the form of memory (non-locality through time) and causally effective spatial structures (non-locality through space). Here it is shown, by construction, how such non-locality can be produced from elementary components: non-isolated systems, multiplicative noise, self-replication, and elimination. A theory is derived that explains how causal non-locality can arise from strictly local interactions.

A model study of assisted adiabatic transfer of population in the presence of collisional dephasing.

Previous studies have demonstrated that when experimental conditions generate non-adiabatic dynamics that prevents highly efficient population transfer between states of an isolated system by stimulated Raman adiabatic passage (STIRAP), the addition of an auxiliary counter-diabatic field (CDF) can restore most or all of that efficiency. This paper examines whether that strategy is also successful in a non-isolated system in which the energies of the states fluctuate, e.g., when a solute is subject to collisions with solvent. We study population transfer in two model systems: (i) the three-state system used by Demirplak and Rice [J. Chem. Phys. 116, 8028 (2002)] and (ii) a four-state system, derived from the simulation studies of Demirplak and Rice [J. Chem. Phys. 125, 194517 (2006)], that mimics HCl in liquid Ar. Simulation studies of the vibrational manifold of HCl in dense fluid Ar show that the collision induced vibrational energy level fluctuations have asymmetric distributions. Representations of these asymmetric energy level fluctuation distributions are used in both models (i) and (ii). We identify three sources of degradation of the efficiency of STIRAP generated selective population transfer in model (ii): too small pulse areas of the laser fields, unwanted interference arising from use of strong fields, and the vibrational detuning. For both models (i) and (ii), our examination of the efficiency of STIRAP + CDF population transfer under the influence of the asymmetric distribution of the vibrational energy fluctuations shows that there is a range of field strengths and pulse durations under which STIRAP + CDF control of population transfer has greater efficiency than does STIRAP generated population transfer.

Seismic isolation technique of marble sculptures at the Accademia Gallery in Florence: numerical calibration and simulation modelling

Isolation technique based on small-size double concave curved surface sliders was studied and applied to Michelangelo’s sculptures placed at the “Galleria dell’Accademia” in Florence, Italy. Starting from preliminary results carried out by some of the authors on such kind of devices, the effect of an enhanced calibration of friction parameters was presented and a number of numerical simulations of both experimental tests and real sculptures under different dynamic conditions were carried out. In particular the experimental tests results were analysed and compared with those obtained for the statues subjected to sinusoidal inputs. Then the sculptures in isolated conditions were subjected to a set of generated accelerograms, compatible with the design spectrum characterizing the Florence site and the main results of the analyses are presented and compared with the case of non-isolated systems.

Extending Noether's theorem by quantifying the asymmetry of quantum states.

Noether's theorem is a fundamental result in physics stating that every symmetry of the dynamics implies a conservation law. It is, however, deficient in several respects: for one, it is not applicable to dynamics wherein the system interacts with an environment; furthermore, even in the case where the system is isolated, if the quantum state is mixed then the Noether conservation laws do not capture all of the consequences of the symmetries. Here we address these deficiencies by introducing measures of the extent to which a quantum state breaks a symmetry. Such measures yield novel constraints on state transitions: for nonisolated systems they cannot increase, whereas for isolated systems they are conserved. We demonstrate that the problem of finding non-trivial asymmetry measures can be solved using the tools of quantum information theory. Applications include deriving model-independent bounds on the quantum noise in amplifiers and assessing quantum schemes for achieving high-precision metrology.

External Lightning Protection and Grounding in Large-Scale Photovoltaic Applications

The development of large-scale photovoltaic (PV) plants in rural areas is constantly increasing. However, the knowledge of performing and installing lightning and surge protection in large-scale PV plants is still premature. The main objective of this paper is to provide a method for assessing the external lightning protection and earthing designs that may be installed in large-scale solar applications. Consequently, the method and models presented in this paper may assist engineers to perform a comparison between the use of isolated and nonisolated lightning protection systems, and second to select suitable surge protection equipment.

Numerical Analysis of the Base-Isolated Rectangular Storage Tanks under Bi-directional Seismic Excitation

Liquid storage tanks are critical elements in the water supply scheme and firefighting system in many industrial facilities for storage of water, oil, chemicals and liquefied natural gas. A common effective method to reduce the seismic response of liquid storage tanks is using baseisolation systems. In this research, the finite element method is used to investigate the seismic behavior of rectangular liquid tanks in three-dimensional domains. The continuous liquid mass of the tank was modeled as lumped masses referred as convective mass, impulsive and rigid mass. The rectangular water tank in two cases base isolated and conventional non-isolated system was selected as a case study. The sloshing displacement and base shear response in two mentioned cases subjected to various ground motions under horizontal components X and Y directions were considered and the results were compared. For this purpose the nonlinear time history analyses of the model were performed. As a result, base isolation was found to be effective in reducing the base shear values, without significantly affecting the sloshing displacements.

Security analysis of the “Ping–Pong” quantum communication protocol in the presence of collective-rotation noise

Environmental noise is inevitable in non-isolated systems. It is, therefore, necessary to analyze the security of the “Ping–Pong” protocol in a noisy environment. An excellent model for collective-rotation noise is introduced, and information theoretical methods are applied to analyze the security of this protocol. If noise level e is lower than 11%, an eavesdropper can gain some, but not all, information freely without being detected. Otherwise, the protocol becomes insecure. We conclude that the use of ‘Ping–Pong’ protocol as a quantum secure direct communication (QSDC) protocol is quasi-secure, as declared by the original author when e⩽11%.

High-Efficiency Single-Phase Transformerless PV H6 Inverter With Hybrid Modulation Method

The main contribution of this paper is the derivation rules summarized from existing high-performance inverters with H6-type configuration, which makes novel topologies possible. In addition, a novel high-efficiency single-phase transformerless photovoltaic inverter with hybrid modulation method is also proposed and evaluated as an example. Without input split capacitors, common-mode voltage and leakage current issues in a nonisolated system with H6-type configuration are eliminated, and the feature of a three-level output voltage in the inverter bridge's middle point helps inductors and power quality optimization. The detailed operation principles with hybrid modulation strategy combined with unipolar and bipolar pulsewidth modulation schemes are presented. Experimental results of a 2200VA prototype verify the proposed topology with hybrid modulation method.

Proposed Principles of Maximum Local Entropy Production

Articles have appeared that rely on the application of some form of "maximum local entropy production principle" (MEPP). This is usually an optimization principle that is supposed to compensate for the lack of structural information and measurements about complex systems, even systems as complex and as little characterized as the whole biosphere or the atmosphere of the Earth or even of less known bodies in the solar system. We select a number of claims from a few well-known papers that advocate this principle and we show that they are in error with the help of simple examples of well-known chemical and physical systems. These erroneous interpretations can be attributed to ignoring well-established and verified theoretical results such as (1) entropy does not necessarily increase in nonisolated systems, such as "local" subsystems; (2) macroscopic systems, as described by classical physics, are in general intrinsically deterministic-there are no "choices" in their evolution to be selected by using supplementary principles; (3) macroscopic deterministic systems are predictable to the extent to which their state and structure is sufficiently well-known; usually they are not sufficiently known, and probabilistic methods need to be employed for their prediction; and (4) there is no causal relationship between the thermodynamic constraints and the kinetics of reaction systems. In conclusion, any predictions based on MEPP-like principles should not be considered scientifically founded.

The fractional oscillator as an open system

Abstract A dynamical system governed by equations with derivatives of non-integer order, such as the fractional oscillator, can be considered as an open (non-isolated) system with memory. Fractional equations of motion are obtained from the interaction between the system and the environment with power-law spectral density.

Critical State Theory in Superconductors

It is well known that the phenomenological balance equation between the Lorentz force and pinning force determines the electric current flow in superconductors in the mixed state. This equation is derived by using the variation principle for isolated or non-isolated flux line system. It might be questionable if this equation is applicable to practical cases, since it is in principle valid only for reversible states with respect to the flux motion. The statistical summation theory that derives the pinning force density from individual pinning potentials solves this problem. It describes the linear relationship between the pinning force density and the displacement of the flux line system in the reversible state and shows that the irreversible pinning force density is reached at the limit of reversible regime. As a result, the present theoretical treatment with existing theories generalizes the phenomenological critical state model to the critical state theory.

Critical State Theory in Superconductors

It is well known that the phenomenological balance equation between the Lorentz force and pinning force determines the electric current flow in superconductors in the mixed state. This equation is derived by using the variation principle for isolated or non-isolated flux line system. It might be questionable if this equation is applicable to practical cases, since it is in principle valid only for reversible states with respect to the flux motion. The statistical summation theory that derives the pinning force density from individual pinning potentials solves this problem. It describes the linear relationship between the pinning force density and the displacement of the flux line system in the reversible state and shows that the irreversible pinning force density is reached at the limit of reversible regime. As a result, the present theoretical treatment with existing theories generalizes the phenomenological critical state model to the critical state theory.

Irreversibility in quantum maps with decoherence

The Boltzmann echo (BE) is a measure of irreversibility and sensitivity to perturbations for non-isolated systems. Recently, different regimes of this quantity were described for chaotic systems. There is a perturbative regime where the BE decays with a rate given by the sum of a term depending on the accuracy with which the system is time reversed and a term depending on the coupling between the system and the environment. In addition, a parameter-independent regime, characterized by the classical Lyapunov exponent, is expected. In this paper, we study the behaviour of the BE in hyperbolic maps that are in contact with different environments. We analyse the emergence of the different regimes and show that the behaviour of the decay rate of the BE is strongly dependent on the type of environment.