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Non-Hermitian optics has revealed a series of counterintuitive phenomena with profound implications for sensing, lasing, and light manipulation. While the non-Hermiticity of Hamiltonians has been intensively investigated, recent advancements in the non-Hermitian scattering matrix have given birth to a lot of unique phenomena, such as simultaneous lasing and anti-lasing, reflectionless scattering modes (RSMs), and coherent chaos control. Despite these developments, the investigation has predominantly focused on static and symmetric configurations, leaving the dynamic properties of non-Hermitian scattering in detuned systems, which is essential for applications in sensing and beyond, largely unexplored. Here, we extend the stationary behaviors associated with the RSMs to resonant detuned systems. Contrary to the common belief of exceptional point (EP) sensors as being susceptible to parametric disturbances, we induce an RSM EP in a one-dimensional optical cavity and demonstrate its robustness in displacement sensing against laser frequency drifts up to 10 MHz. Our findings not only contribute to the broader understanding of non-Hermitian scattering phenomena but also pave the way for the next generation of non-Hermitian sensors. [ABSTRACT FROM AUTHOR]

Background: The minimum admissible detuning efficiency (DE) of a receive coil is an essential parameter for coil designers. A receive coil with inefficient detuning leads to inhomogeneous B1 during excitation. Previously proposed criteria for quantifying the DE rely on indirect measurements and are difficult to implement. Purpose: To present an alternative method to quantify the DE of receive‐only surface coils. Study Type: Theoretical study supported by simulations and phantom experiments. Phantoms: Uniform spherical (100 mm diameter) and cylindrical (66 mm diameter) phantoms. Field Strength/Sequence: Dual repetition time B1 mapping sequence at 1.5T, and Bloch‐Siegert shift B1 mapping sequence at 3.0T. Assessment: One non‐planar (80 × 43 mm2) and two planar (40 and 57 mm diameter) surface coils were built. Theoretical analysis was performed to determine the minimum DE required to avoid B1 distortions. Experimental B1 maps were acquired for the non‐planar and planar surface coils at both 1.5T and 3.0T and visually compared with simulated B1 maps to assess the validity of the theoretical analysis. Statistical Tests: None. Results: Based on the theoretical analysis, the proposed minimum admissible DE, defined as DEthr = 20 Log (Q) + 13 dB, depended only on the quality factor (Q) of the coil and was independent of coil area and field strength. Simulations and phantom experiments showed that when the DE was higher than this minimum threshold level, the B1 field generated by the transmission coil was not modified by the receive coil. Data Conclusion: The proposed criterion for assessing the DE is simple to measure, and does not depend on the area of the coil or on the magnetic field strength, up to 3T. Experimental and simulated B1 maps confirmed that detuning efficiencies above the theoretically derived minimal admissible DE resulted in a non‐distorted B1 field. Evidence Level: 2 Technical Efficacy: Stage 1 [ABSTRACT FROM AUTHOR]

A power tracking method based on improved variable‐step perturbation observation approach has been proposed in this paper. This method is aimed at addressing the detuning issues caused by capacitor parameter drift in MCR‐WPT systems based on S‐S compensation circuits. Compared with traditional tuning methods, the proposed method has fast response, high accuracy, low complexity, and less prone to over‐tracking. Firstly, a mathematical model of the system based on the detuning factor has been established. Secondly, the impact of different detuning conditions on the system at the initial resonant frequency has been studied. Thirdly, the response characteristics of the system to different frequencies under different detuning conditions have been studied. Fourthly, based on the above researches, an improved variable‐step perturbation observation method based on the single‐step power drop factor has been proposed. Finally, an experimental platform was constructed, and relevant experiments were conducted. Experimental results validate the effectiveness of power tracking under different detuning conditions, with the lowest transmission efficiency being 81.51%. [ABSTRACT FROM AUTHOR]

One of the fundamental arguments in quantum information theory is the uncertainty principle. According to this principle, two incompatible observables cannot be measured with high precision at the same time. In this work, we will use the entropic uncertainty relation in the presence of quantum memory. Considering a dissipative environment, the effects of the detuning between the transition frequency of a quantum memory and the center frequency of a cavity on entropic uncertainty bound and the quantum correlation between quantum memory and measured particle will be studied. It is shown that by increasing the detuning, quantum correlation is maintained. As a result, due to the inverse relationship between the uncertainty bound and quantum correlations, the measurement results are guessed more accurately. [ABSTRACT FROM AUTHOR]

Non-Hermitian optics has revealed a series of counterintuitive phenomena with profound implications for sensing, lasing, and light manipulation. While the non-Hermiticity of Hamiltonians has been intensively investigated, recent advancements in the non-Hermitian scattering matrix have given birth to a lot of unique phenomena, such as simultaneous lasing and anti-lasing, reflectionless scattering modes (RSMs), and coherent chaos control. Despite these developments, the investigation has predominantly focused on static and symmetric configurations, leaving the dynamic properties of non-Hermitian scattering in detuned systems, which is essential for applications in sensing and beyond, largely unexplored. Here, we extend the stationary behaviors associated with the RSMs to resonant detuned systems. Contrary to the common belief of exceptional point (EP) sensors as being susceptible to parametric disturbances, we induce an RSM EP in a one-dimensional optical cavity and demonstrate its robustness in displacement sensing against laser frequency drifts up to 10 MHz. Our findings not only contribute to the broader understanding of non-Hermitian scattering phenomena but also pave the way for the next generation of non-Hermitian sensors.

The study of damage mechanisms for wind turbine blades is important. Generally, modal localization tends to accelerate structural damage. This is a new approach to studying these damage mechanisms for wind turbine blades through modal localization theory. Therefore, this paper investigates whether modal localization phenomena exist in wind turbine blades, as well as the impact of different forms of detuning on modal localization. Based on perturbation theory, a mechanism for mode localization is described quantitatively using the degree of detuning, the degree of mode density, and the mode assurance criterion. A finite element model for wind turbine blades was established using ANSYS software (R15.0), and three detuning cases were simulated by changing the density, elastic modulus, and installation angles of the blades. Moreover, an improved mode localization factor is proposed to quantitatively evaluate the degree of mode localization in wind turbine blades. The numerical results indicate that the degree of modal localization increases with an increasing degree of detuning, but the increase in modal localization gradually slows. Finally, the detuning modal shape composition, which includes harmonic components, is analyzed. The results show that the closer the composition of the detuning modes is, the stronger the degree of mode localization. [ABSTRACT FROM AUTHOR]

Photoassociation (PA) of 85Rb atoms from the ground X 1 Σ g + state to the excited A 1 Σ g + and b 3 Π u states by two-color laser pulses at 100 μ K × k B is investigated by using quantum wavepacket method. Two pulses with detunings δ 1 and δ 2 varying from −1.0 to 1. cm−1 are taken into account. The specific case δ 1 = − δ 2 is generalized to the condition of arbitrary combination of δ 1 and δ 2 for both the Gaussian-pulse field and the slowly-turned-on and rapidly-turned-off (STRT) field. It is found that the introduce of the detunings in the two pluses can enhance the asymmetry of the time profile and broaden the linewidth of the laser field. The two factors can further enhance the PA probability for both resonant and nonresonant regions. Compared to the Gaussian field, the STRT field which is even more asymmetric in time profile and more broaden in linewidth can significantly enhance the PA probability, with the nonresonant transition dominating the PA process. It can be expected that once the two detunings are both positive, which is a relatively loose restriction for coherent control, a considerable PA probability can be obtained in a two-color STRT field. [ABSTRACT FROM AUTHOR]

IntroductionInterventional cardiac MRI in the context of the treatment of cardiac arrhythmia requires submillimeter image resolution to precisely characterize the cardiac substrate and guide the catheter-based ablation procedure in real-time. Conventional MRI receiver coils positioned on the thorax provide insufficient signal-to-noise ratio (SNR) and spatial selectivity to satisfy these constraints.MethodsA small circular MRI receiver coil was developed and evaluated under different experimental conditions, including high-resolution MRI anatomical and thermometric imaging at 1.5 T. From the perspective of developing a therapeutic MR-compatible catheter equipped with a receiver coil, we also propose alternative remote active detuning techniques of the receiver coil using one or two cables. Theoretical details are presented, as well as simulations and experimental validation.ResultsAnatomical images of the left ventricle at 170 µm in-plane resolution are provided on ex vivo beating heart from swine using a 2 cm circular receiver coil. Taking advantage of the increase of SNR at its vicinity (up to 35 fold compared to conventional receiver coils), real-time MR-temperature imaging can reach an uncertainty below 0.1°C at the submillimetric spatial resolution. Remote active detuning using two cables has similar decoupling efficiency to conventional on-site decoupling, at the cost of an acceptable decrease in the resulting SNR.DiscussionThis study shows the potential of small dimension surface coils for minimally invasive therapy of cardiac arrhythmia intraoperatively guided by MRI. The proposed remote decoupling approaches may simplify the construction process and reduce the cost of such single-use devices.

From the point of view of perturbation theory, (perturbations of) near-resonant systems are plagued by small denominators. These do not affect (perturbations of) fully resonant systems; so it is in many ways convenient to approximate near resonant systems as fully resonant ones, which correspond to considering the "detuning" as a perturbation itself. This approach has proven very fruitful in Classical Mechanics, but it is also standard in (perturbations of) Quantum Mechanical systems. Actually, its origin may be traced back (at least) to the Rayleigh-Ritz method for computing eigenvalues and eigenvectors of perturbed matrix problems. We will discuss relations between these approaches, and consider some case study models in the different contexts.

The study of damage mechanisms for wind turbine blades is important. Generally, modal localization tends to accelerate structural damage. This is a new approach to studying these damage mechanisms for wind turbine blades through modal localization theory. Therefore, this paper investigates whether modal localization phenomena exist in wind turbine blades, as well as the impact of different forms of detuning on modal localization. Based on perturbation theory, a mechanism for mode localization is described quantitatively using the degree of detuning, the degree of mode density, and the mode assurance criterion. A finite element model for wind turbine blades was established using ANSYS software (R15.0), and three detuning cases were simulated by changing the density, elastic modulus, and installation angles of the blades. Moreover, an improved mode localization factor is proposed to quantitatively evaluate the degree of mode localization in wind turbine blades. The numerical results indicate that the degree of modal localization increases with an increasing degree of detuning, but the increase in modal localization gradually slows. Finally, the detuning modal shape composition, which includes harmonic components, is analyzed. The results show that the closer the composition of the detuning modes is, the stronger the degree of mode localization.

The creation of a coherent superposition of states in a system consisting of N -ground states and an excited state using the shortcut to adiabatic passage method has been investigated. In this method, each of the ground states is paired with an excited state by two laser pulses. We show that the problem can be reduced to the solution of a two-state system involving a superposition of all ground states and the excited state. We consider the excited state as the initial state of the system and show that by using the shortcut to adiabatic passage method, we can create an arbitrary superposition of the ground states. In comparison with the other methods, detuning is time-dependent, and this method provides a fast and robust approach to create an arbitrary coherent superposition of the ground states. [ABSTRACT FROM AUTHOR]

High-density coil installation to achieve a smooth power transfer inevitably increases construction costs, reducing the acceptance of dynamic wireless power transfer (DWPT). In this article, a detuning-repeater-based DWPT system is proposed to provide a relatively constant power at a reduced count of inverters. Half of the inverter-connected transmitter coils in conventional DWPT systems are served as passive repeater coils. The repeater relays the power from the transmitters on both sides to take the role of the main power transfer channel when the receiver is moving towards it. A detuning method is proposed to suppress the standby currents inside the idle repeater coils by utilizing the variation of receiver reflecting impedance during the receiver moving towards/away. An optimization method to achieve less power fluctuation is designed based on the detuning rate. The tradeoff between the power fluctuation and current suppression is analyzed. The system performance against parameter variations is also performed. A 100 W down-sized prototype is developed, and the experimental results show that the proposed DWPT system can achieve a quasi-constant output power with a power fluctuation of 8.5% and a system efficiency of around 82% during the entire dynamic process. [ABSTRACT FROM AUTHOR]

From the point of view of perturbation theory, (perturbations of) near-resonant systems are plagued by small denominators. These do not affect (perturbations of) fully resonant systems; so it is in many ways convenient to approximate near resonant systems as fully resonant ones, which correspond to considering the "detuning" as a perturbation itself. This approach has proven very fruitful in Classical Mechanics, but it is also standard in (perturbations of) Quantum Mechanical systems. Actually, its origin may be traced back (at least) to the Rayleigh-Ritz method for computing eigenvalues and eigenvectors of perturbed matrix problems. We will discuss relations between these approaches, and consider some case study models in the different contexts. [ABSTRACT FROM AUTHOR]

ABSTRACTAlthough forbidden band effect in perfectly periodic phononic crystals (PC) is very attractive, random disordered (i.e. detuning) phenomenon is inevitable in engineering processing, thus exploring the effect of detuning on the wave characteristics of PC becomes a necessity. In this study, fundamental governing equations and boundary conditions are derived from the principle of virtual work. Wave characteristics and localization factor of one-dimensional (1D) detuned nano-PC are investigated based on the transfer matrix method, with flexoelectric effect duly accounted for. Subsequently, with [Formula: see text] nano-PC taken for illustration, forbidden band properties and localization factor of 1D elastic waves in harmonic and detuned states are systematically characterized. It is demonstrated that localization factor can characterize the energy band structure of 1D PC perfectly. Flexoelectric effect tends to widen the width of forbidden band with increasing detuning, and detuning is linearly related to the bandwidth. The forbidden band is more sensitive to flexoelectric coefficient detuning than thickness detuning. The research results provide useful theoretical guidance for designing high-frequency nanoscaled devices with the function of filtering based on band gap effect of nano-PC.

Although forbidden band effect in perfectly periodic phononic crystals (PC) is very attractive, random disordered (i.e. detuning) phenomenon is inevitable in engineering processing, thus exploring the effect of detuning on the wave characteristics of PC becomes a necessity. In this study, fundamental governing equations and boundary conditions are derived from the principle of virtual work. Wave characteristics and localization factor of one-dimensional (1D) detuned nano-PC are investigated based on the transfer matrix method, with flexoelectric effect duly accounted for. Subsequently, with B a T i O 3 − S r T i O 3 nano-PC taken for illustration, forbidden band properties and localization factor of 1D elastic waves in harmonic and detuned states are systematically characterized. It is demonstrated that localization factor can characterize the energy band structure of 1D PC perfectly. Flexoelectric effect tends to widen the width of forbidden band with increasing detuning, and detuning is linearly related to the bandwidth. The forbidden band is more sensitive to flexoelectric coefficient detuning than thickness detuning. The research results provide useful theoretical guidance for designing high-frequency nanoscaled devices with the function of filtering based on band gap effect of nano-PC. [ABSTRACT FROM AUTHOR]

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In this work, the authors investigated the dynamics of entanglement of two identical two-level atoms (qubits) in the framework of the two-photon double Jaynes–Cummings model, taking into account the detuning between atoms and the double frequency of the field modes of the resonators, as well as the Kerr medium in both resonators. The authors derived the time dependence of the negativity parameter for the Bell initial states of the atoms and the vacuum states of the resonator fields. The results showed that detuning and Kerr nonlinearity leads to stabilization of the entanglement for all initial Bell-type atomic states. For some initial atomic entanglement states, the detuning and Kerr environment in the resonators can prevent the effect of sudden death of the atom-atom entanglement.

In this article, author investigated the dynamics of entanglement of two dipole-coupled natural or artificial two-level atoms (qubits) interacting nonresonantly with the intensive one-mode cavity thermal field. Author found an exact solution of the quantum Liouville equation for the full density matrix of the system two atoms + field mode for a coherent initial state of atoms in the dressed states representation. The full system density matrix is used to calculate the two-atom reduced density matrix and to calculate the quantitative criterion for atom-atom entanglement ‒ negativity. The results of computer simulation of the time dependence of negativity showed that in the case of a model with nonresonant interaction, the presence of initial atomic coherence leads to a significant decrease in the maximum degree of atomic entanglement, in contrast to the model with resonant interaction of atoms and a field. For the resonance model, the initial atomic coherence greatly enhances the degree of atomic entanglement.

In the magnetically coupled resonant wireless power transfer (MCR-WPT) system, parameter variations of the resonant network will cause the resonant frequency drift, which will make the system in the detuning state. The detuning will increase the required capacity of the power supply and reduce the transfer efficiency of the system. To solve this problem, this paper analyzes the relation between the input impedance angle of the primary side and the resonant state and proposes an adaptive frequency tracking control (AFTC) method based on the fuzzy PI compound controller. In this method, a fuzzy PI compound controller is used to control the impedance angle (θ = 0), which can make the operating frequency to track the resonant frequency, so that the MCR-WPT system can maintain in the resonant state. The experimental results show that the AFTC method can make the operating frequency to track the resonant frequency faster and accurately during the parameter variations so that the MCR-WPT system can maintain in the resonant state and achieve the higher output power and system efficiency. [ABSTRACT FROM AUTHOR]

The seismic roles of non-structural parts have been extensively investigated, and conclusions have been drawn that non-structural components and objects contribute to both dynamic features and seismic loss of structural systems. In light-weighted seismic-response-control structures wherein non-structural parts could compose a non-negligible portion of the total weight, the aforementioned roles could be amplified, possibly disrupting beneficial structural characteristics. Current studies have yet to systematically investigate the dynamic interaction effects between a tuning structure and non-structural objects. This study addresses this gap and particularly explores three major pairs of free-standing object behavior in different directions, namely, sliding-impact, rocking-overturning, and throwing-landing, as well as the influences on the seismic response control of mega-sub-control suspended buildings. Comprehensive frequency- and time-domain analyses are conducted, while tuning indices, object-structure response correlation, and object statistics are also calculated to interpret the phenomena. Results show that, with a linear structure, pure sliding reduces low-frequency responses of both primary and secondary structures, while throwing reduces high-frequency ones; other types of interactions are overall detrimental. As excitation intensifies, the interactions become more beneficial to high-frequency responses and detrimental to low-frequency responses. With a nonlinear structure subjected to seismic excitation, structural period-elongation mixes with interaction-induced detuning; the detrimental effects on the primary structure are undermined and thus overwhelmed by beneficial ones. At the PGV level of 0.7 m/s, the maximum of averaged envelopes of seismic-induced primary structure displacement show a 9 % reduction, while those of secondary structure horizontal acceleration show a 185 % increment caused by object-structure interactions. Sliding accompanied by impact is statistically identified as the major detrimental factor for secondary structure acceleration, and the effect is sensitive to the located floor level of the object. • Dynamic interactions between the free-standing objects and the mega-sub-control suspended buildings are investigated. • Free-standing object behaviors are considered, including sliding-impact, rocking-overturning, and throwing-landing. • The detrimental effects of interaction-induced detuning and transient dynamic behaviors are identified. • The beneficial additional dissipation can compensate for the detrimental interaction-induced detuning in certain scenarios. [ABSTRACT FROM AUTHOR]

We investigated the patterns of coordination between the left and right legs that support the task of maintaining an upright standing posture. We used cross-wavelet analyses to assess coordination between the centers of pressure under the left and right feet. We recruited participants with a lateralized functional preference for their right leg, and we manipulated whether these participants stood with symmetric/asymmetric stances and whether their eyes were open or closed. Our hypotheses were derived from the Haken-Kelso-Bunz (HKB) model of interlimb coordination dynamics. Consistent with HKB model predictions, we observed (1) coordination taking the form of metastable, transient epochs of stable phase relations, (2) preferences for in-phase and anti-phase coordination patterns, and (3) changes in pattern stability and phase leads associated with both stance asymmetry and right-side lateral preference. The form and stability of observed coordination patterns were mediated by the availability of visual information. Our findings confirm the existence of a metastable coordination dynamic associated with the task of maintaining upright stance. We discuss the implications of these findings in the context of evaluating the utility of the HKB model for understanding the functional organization of the posture system. [ABSTRACT FROM AUTHOR]

This paper reports on 3-dB down bandwidth of 110.6 GHz by direct modulation of a coupled cavity DFB-LD with phase-shifted/uniform gratings due to photon-photon resonance when the injected current is 3.5 times the threshold current. The photon-photon resonance between the main-mode and sub-mode is analyzed from the viewpoint of threshold gain and detuning between the main-mode and sub-mode. It is found that the detuning between the main-mode and sub-mode contributes to enhancement of the 3-dB down bandwidth. [ABSTRACT FROM AUTHOR]

In the present paper we studied the entanglement of a quantum system consisting of two dipole-coupled two-level atoms, one of which interacts with one-mode thermal field in a lossless cavity, and another is outside a cavity. We obtained the analytical expression of the atom-atom negativity for separable initial atomic state and investigated the influence of a detuning between the atom and the field frequencies and direct dipole-dipole interaction on an atom-atom entanglement. We derived that detuning might cause high atom-atom entanglement in the presence of the dipole-dipole interaction. We also showed that the detuning and dipole-dipole interaction are an effective mechanisms for control and operation of the atomic entanglement.

Of great interest in the many fields of communication is the requirement to place numerous small antenna elements in close proximity or even inside one another for diversity or mutiband usage. This letter aims to describe the effects of such adjacency in terms of physical distance and operating frequencies as a function of the volume overlap of circumscribing Wheeler–Chu spheres. We investigate any potential bandwidth advantage or in shared near-field space and define tradeoffs between space minimization and acceptable degradation for electrically small antennas. We find that contrary to popular belief among many antenna designers, it is not possible for two antennas having similar modes to reuse volume without suffering degradation in performance, particularly bandwidth. [ABSTRACT FROM AUTHOR]

This work is devoted to the robust analysis of the effects of geometric nonlinearities on the nonlinear dynamic behavior of rotating detuned (intentionally mistuned) bladed disks in presence of unintentional mistuning (simply called mistuning). Mistuning induces uncertainties in the computational model, which are taken into account by a probabilistic approach. This paper presents a series of novel results of the dynamic behavior of such rotating bladed disks exhibiting nonlinear geometric effects. The structural responses in the time domain are analyzed in the frequency domain. The frequency analysis exhibits responses outside the frequency band of excitation. The confidence region of the stochastic responses allows the robustness to be analyzed with respect to uncertainties and also allows physical insights to be given concerning the structural sensitivity. The bladed disk structure is made up of 24 blades for which several different detuned patterns are investigated with and without mistuning. [ABSTRACT FROM AUTHOR]

We consider the situation that two atomic ensembles are separately trapped in coupled single-mode cavities, and each atom non-resonantly interacts with cavity field via a one-photon hopping. By employing the negativity measure of entanglement, we investigate the temporal evolution of entanglements between the cavities as well as between the cavity and atomic ensemble. By means of the numerical calculations, we discuss the influences of the number of atoms in an atomic ensemble and the detuning on the entanglement. The results show that as the number of atoms increases, the entanglement between the cavities is strengthened, contrary the entanglement between atomic ensemble and cavity is weakened. On the other hand, as the detuning increases, the entanglement between the cavities is weakened, contrary the entanglement between atomic ensemble and cavity is strengthened. [ABSTRACT FROM AUTHOR]

We investigate the entanglement dynamics of two atoms in a double damping Jaynes-Cummings model. The two atoms are initially in the Bell states and each is in a squeezed vacuum cavity field or coherent cavity field. Compared with the case in coherent field, the atomic entanglement in the squeezed vacuum field is stronger under the same conditions. The results show that we can adopt appropriate parameters such as mean photon number, detuning, the atomic spontaneous decay and the cavity decay, to realize better control of atomic entanglement in quantum information processing. What's worth mentioning is that proper choosing of the last two parameters enables us to decrease disentanglement period and postpone the moment when the entanglement disappears. Finally, the atomic entanglement in double damping and non-identical Jaynes-Cummings model is obtained [ABSTRACT FROM AUTHOR]

In this paper we have investigated the dynamics of entanglement of two identical qubits nonresonantly interacting with one mode of a thermal electromagnetic field in lossless resonator in the presence of a direct dipole-dipole interaction. On the basis of the exact solution of the considered model, the Peres-Horodetskii entanglement parameter (negativity) for qubits has been found. Numerical simulation of the negativity for various model parameters has been carried out. It has been shown that the interaction of qubits with the thermal field of the resonator can lead to their entanglement. It ha been established that the detuning and dipole-dipole interaction of qubits can be used to manipulate and control the degree of their entanglement.

Standard vector controllers for induction machines (IMs) are based on the conventional IM model. Consequently, they are unaware of the existence of stray load and iron losses. However, these losses may induce a considerable mismatch between the actual and reference flux vectors in vector controllers. This mismatch is greatly affected by the operating flux and load. In this paper, two different approaches are considered for compensation of this mismatch—the first involves investment in IMs with low stray load and iron losses, whereas the other involves development of a control algorithm in which both these losses are compensated. The performance of the developed vector controller is compared to the standard controller and tested on three small IMs of different efficiency class and rotor cage material (aluminum versus copper). Simulation and experimental testing is carried over wide ranges of loads, speeds, and magnetization levels. The estimated rotor speed is used as a measure of the controller detuning. A standard estimator that utilizes rotor flux-linkage estimates within the model reference adaptive system is here for the first time modified to include stray load and iron losses. Finally, problems regarding numerical integration, sampling frequency, and temperature-induced variations of IM parameters are addressed. [ABSTRACT FROM AUTHOR]

Considering the generalized double Jaynes-Cummings model, we examine the entanglement between two non-identical dipole-dipole coupled qubits interacting with two independent detuned vacuum cavity modes. We calculate the negativity as a measure of qubits entanglement. We find that entanglement parameter evolve periodically with time and the period are affected by the model parameters and initial states of qubits. For unentangled initial states the detuning and dipole-dipole interaction affect only the period of entanglement oscillations, not the maximum value of entanglement. For entangled states the detuning stabilizes the entanglement parameter oscillations. According to choice of initial entangled state the dipole-dipole strength is greatly enhances or weakens the oscillations of the entanglement parameter. [ABSTRACT FROM AUTHOR]

We consider the case that the two-level atom off-resonantly interacts with cavity field via a one-photon hopping in double Jaynes-Cummings system. Geometrical quantum discord (GQD) is adopted to quantify the degree of correlation between two subsystems. GQD dynamics between two atoms, between cavity fields, as well as between atom and cavity fields are studied. The influences of detuning on GQD are discussed. The results obtained using the numerical method show that GQD between two atoms, between cavity fields, and between atom and cavity fields all display periodic oscillations. Furthermore, their periodic oscillations frequencies increase with the increase of detuning. On the other hand, GQD between two cavity fields and that between atom and cavity are weakened with increase of detuning. [ABSTRACT FROM AUTHOR]

Silicon-based quantum computing has the potential advantages of low cost, high integration density, and compatibility with CMOS technologies. The detuning mechanism has been used to experimentally achieve silicon two-qubit quantum gates and programmable quantum processors. In this paper, the scaling behaviors and variability issues are explored by numerical device simulations of a model silicon quantum gate based on the detuning mechanism. The device physics of quantum gates modulation, tradeoff between device speed and quantum fidelity, and impact of variability on the implementation of a quantum algorithm are examined. The results indicate the attractive potential to achieve high speed and fidelity silicon quantum gates with a low operation voltage. To scale up, reducing the device variability and mitigating the variability effect are identified to be indispensable for reliable implementing a quantum computing algorithm with the silicon quantum gates based on the detuning mechanism. A scheme to use the control electronics for mitigating the variability of quantum gates is proposed. [ABSTRACT FROM AUTHOR]

We studied the entanglement of a quantum system consisting of a Jaynes-Cummings atom, thermal lossless cavity and an isolated atom. The analytical expressions of the atom-atom negativity for separable and entangled initial atomic states were obtained. The influence of a detuning between the atomic transition frequency and the field frequency and direct dipole-dipole interaction on an atom-atom entanglement is examined. We showed that for a separable initial atomic states a detuning might cause high atom-atom entanglement in the presence of the dipole-dipole interaction. We also obtained that for an entangled initial atomic state a detuning causes a stabilization of an entanglement oscillations both for model with dipole-dipole interaction and model without such interaction. [ABSTRACT FROM AUTHOR]

The phenomena of curve veering, encompassing frequency loci veering and modal jumping, are investigated in the context of spherical reticulated shells by incorporating random detuning parameters with a Gaussian distribution into the mass matrix. The Finite Element Method (FEM) is systematically employed to investigate the effects of the assumed mass detuning patterns on the natural frequencies and modal shapes exhibited by a spherical reticulated shell. Our findings reveal the presence of frequency loci veering in certain typical detuning scenarios. Subsequently, the Frequency Veering Index (FVI) is proposed to determine the position of veering points. In conjunction, the occurrence of the mode jumping phenomenon is observed in proximity to veering points. The Modal Assurance Criterion (MAC) is proposed as a metric to evaluate the mode jumping phenomenon, and the number of veering points is ascertained through statistical analysis. Ultimately, the matrix perturbation method is employed to validate the underlying mechanisms of frequency loci veering and mode jumping phenomena, while a simplified model is utilized to provide a deeper understanding of their intrinsic nature. • Investigating curve veering in spherical reticulated shells using Gaussian-distributed detuning parameters via FEM. • Findings reveal frequency loci veering in certain scenarios; introducing Frequency Veering Index to identify veering points. • Observing mode jumping phenomenon near veering points; proposing Modal Assurance Criterion (MAC) for evaluation. • Statistical analysis used to determine the number of veering points. • Matrix perturbation method validates frequency loci veering and mode jumping, while a simplified model enhances understanding. [ABSTRACT FROM AUTHOR]

The nonlinear parity-time-symmetric wireless power transfer (NPTS-WPT) system is more robust against transfer distance than the traditional WPT system. Current studies mainly focus on the situation in which the transmitter (Tx) and the receiver (Rx) are completely matched. Our study focuses on the transfer characteristics of the NPTS-WPT system under detuning between the Tx and the Rx. First, the mathematical model of the detuned system is established, and then the model is solved using Shengjin’s formula. Then, the exact analytical solutions for the operating frequency, the amplification factor of the operational amplifier (OP Amp) and the transfer efficiency at detuning are obtained. It was noted, for the first time, that even though the Tx and the Rx were completely matched, a frequency jump could occur when the distance between the Tx and Rx coils slowly changed. Our study found that when the degree of detuning of the system changed, the operating frequency of the system could jump. By investigating the amplification factor of the OP Amp, the reason for the frequency jump when the system was detuned was explained. Our study also revealed that detuning did not imply a decreased transfer efficiency, and the over-detuning can improve the transfer efficiency sometimes. Finally, an experimental system was constructed, and the correctness of the theory was validated using the experimental system.

This paper evaluates different types of AC machines and various control techniques for their suitability for the drive system of Alternative Energy Vehicles (AEV). An Indirect Field Oriented (IFO) drive system for the AEV application is chosen and its major problem of detuning is addressed by designing an offline and an online rotor resistance adaptation technique. The offline scheme sets the slip gain at various operating conditions based on the fact that if the rotor resistance is set correctly and field orientation is achieved, then there should be a linear relationship between the torque current and the output torque. The online technique is designed using Model Reference Adaptive System (MRAS) for the rotor resistance adaptation. For an ideal field oriented machine, the rotor flux along the q-axis should be zero. This condition acts as a reference model for the proposed MRAS scheme. The current model flux observer in the synchronous frame of reference is selected as an adjustable model and its rotor resistance is tuned so that the flux along the q-axis becomes zero. The effectiveness of the offline tuning scheme is evident through performance validation of the drive system, which is implemented in a real Ford vehicle. The experimental results obtained while driving the test vehicle are included in the paper while the proposed online scheme is validated on a 3.75 kW prototype induction motor.

Introduction: Interventional cardiac MRI in the context of the treatment of cardiac arrhythmia requires submillimeter image resolution to precisely characterize the cardiac substrate and guide the catheter-based ablation procedure in real-time. Conventional MRI receiver coils positioned on the thorax provide insufficient signal-to-noise ratio (SNR) and spatial selectivity to satisfy these constraints., Methods: A small circular MRI receiver coil was developed and evaluated under different experimental conditions, including high-resolution MRI anatomical and thermometric imaging at 1.5 T. From the perspective of developing a therapeutic MR-compatible catheter equipped with a receiver coil, we also propose alternative remote active detuning techniques of the receiver coil using one or two cables. Theoretical details are presented, as well as simulations and experimental validation., Results: Anatomical images of the left ventricle at 170 µm in-plane resolution are provided on ex vivo beating heart from swine using a 2 cm circular receiver coil. Taking advantage of the increase of SNR at its vicinity (up to 35 fold compared to conventional receiver coils), real-time MR-temperature imaging can reach an uncertainty below 0.1°C at the submillimetric spatial resolution. Remote active detuning using two cables has similar decoupling efficiency to conventional on-site decoupling, at the cost of an acceptable decrease in the resulting SNR., Discussion: This study shows the potential of small dimension surface coils for minimally invasive therapy of cardiac arrhythmia intraoperatively guided by MRI. The proposed remote decoupling approaches may simplify the construction process and reduce the cost of such single-use devices., Competing Interests: MD did part of her Ph.D as an employee of Siemens Healthineers. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (© 2023 Marhabaie, Delcey, El Hamrani, Vaillant, Ginefri, Ozenne, Abell, Poirier-Quinot and Quesson.)

Tuned mass damper (TMD) has been one of the most commonly used passive vibration control devices over the past few decades. While an optimally designed TMD can significantly suppress the structural vibration, detuning often occurs due to various reasons such as change in operating conditions or variation in primary structure properties, resulting in degradation of TMD’s performance. In order to restore its performance, it is necessary to estimate the modal properties of the primary structure, and perform the re-tuning process. Such an exercise requires powerful signal processing methods to successfully extract the structural modes in the presence of closely-spaced modes. This study focuses on the identification of modal frequencies and damping of the structure installed with a TMD. In view of the advantages and limitations of existing modal identification methods, this paper provides a new technique that combines the second-order blind identification (SOBI) method with the empirical wavelet transform (EWT) to delineate closely-spaced frequencies. While the SOBI method does not guarantee the separation of closely-spaced modes and suffers from the limitation of generating mode-mixed modal responses, the EWT operates on the modal responses estimated by the SOBI and yields the closely-spaced natural frequencies. The proposed method is illustrated using a six-story simulation model with a wide range of detuning cases. An experiment on a three-story bench-scale model equipped with a TMD is also conducted to validate the applicability of the proposed method. [ABSTRACT FROM AUTHOR]

Linear proportional-integral (PI) controllers are an attractive choice for controlling the speed of induction machines because of their simplicity and ease of implementation. Fractional-order PI (FO-PI) controllers, however, perform better than PI controllers because of their nonlinear nature and the underlying iso-damping property of fractional-order operators. In this work, an FO-PI controller based on the proposed first-order plus dead-time induction motor model and integer-order (IO) controllers, such as Ziegler-Nichols PI, Cohen-Coon PI, and a PI controller tuned via trial-and-error method, is designed. Simulation and experimental investigation on an indirect field-oriented induction motor drive system proves that the proposed FO-PI controller has better speed tracking, lesser settling time, better disturbance rejection, and lower speed tracking error compared with linear IO-PI controllers. Our experimental study also validates that the FO-PI controller maximizes the torque per ampere output of the induction machine and can effectively control the motor at low speed, in field-weakening regions, and under detuned conditions. [ABSTRACT FROM AUTHOR]

The tripartite Negativity is adopted to quantify the degree of entanglement among three subsystems. The situation is considered that three identical two-level atoms are trapped in a single-mode optical cavity, and each atom off-resonantly interacts with cavity field via a one-photon hopping. When there is a dipole-dipole interaction between atoms, the tripartite entanglement dynamics among atoms is studied. The influences of detuning between atom and cavity field and the strength of dipole-dipole interaction of two atoms on the tripartite entanglement are discussed. The calculation results indicate that the tripartite entanglement among atoms is strengthened with increasing of the detuning, and it is also strengthened with increasing of the strength of dipole-dipole interaction of two atoms. Under the case of large detuning, the tripartite entanglement among atoms exhibits quasi-periodic oscillations, and its oscillation frequency is accelerated with increasing of the strength of dipole-dipole interaction between two atoms. [ABSTRACT FROM AUTHOR]

We investigate the effects of a third laser on the electromagnetically induced transparency (EIT) spectrum obtained for the D 2 line of 87Rb. The third laser converts a typical bi-chromatic laser-induced Λ type system into a four-level N type system. Our work considers two different configurations of N type system depending on whether the third laser is co-propagating or counter-propagating with respect to the other two. The effects of detuning on the EIT spectrum for both cases of N type systems have been experimentally studied. Our results demonstrate that for the counter-propagating case variation of detuning induces a switch from absorption to transmission. We interpret the experimental observations in terms of modification of light shifts by Doppler averaging within a dressed state formalism. Numerical results obtained using the density matrix formulation, which is in good agreement with the experimental results are also included to substantiate the experimental findings. We also find that in the presence of a magnetic field, due to the formation of certain subsystems that involves Zeeman sublevels, neither absorption nor transmission is observed in the probe transmission spectrum. We define these as the "missing resonance" peaks. We propose methods for recovering these peaks in the probe transmission spectrum. • Three laser systems are studied in D 2 line of 87Rb. • Detuning dependent switching of resonances. • Modification in probe response due to Doppler dependent light shifts. • N-type model system explains the experimental observations. • Competition between Vee and Lambda systems in presence of a magnetic field. [ABSTRACT FROM AUTHOR]

Wireless power transmission (WPT) uses a loosely coupled transformer to transmit electric energy. The resulting system's transmission efficiency and distance are affected by factors such as, inductance parameter and resonance frequency offset. To reduce the influence of detuning on transmission efficiency, a frequency tracking method based on the hill-climbing algorithm was proposed in this study. The WPT model was established to depict the detuning mechanism and the transmission efficiency affected by natural frequency changes in the primary and secondary coils. Experimental data were used to prove the correctness of the theoretical analysis. Results demonstrate that the coupling coefficient of the two coils is proportional to the increase of the distance between the transmitting and receiving coils. Hence, coupling coefficient influences transmission efficiency. Another important factor is distance S, as its increase leads to mutual loss, which breaks the previous state of the best resonance compensation, which in turn reduces the transmission efficiency of WPT. When distance S increases from 10 mm to 30 mm and the system has no frequency tracking, the transmission efficiency decreases from 45% to 7.5%. However, when distance S increases from 10 mm to 30 mm and the system has frequency tracking, the transmission efficiency decreases from 70% to 19.1%. When distance S is equidistant, the transmission efficiency is much higher with than without frequency tracking. The proposed method can effectively raise the transmission efficiency of the WPT system and control the cost of hardware, which optimizes practical engineering design. [ABSTRACT FROM AUTHOR]

Geometrical quantum discord (GQD) is adopted to quantify the degree of correlation between two subsystems. We consider the situation that two two-level atoms are separately trapped in coupled single-mode cavities, and each atom non-resonantly interacts with cavity via a one-photon hopping. GQD dynamic between atoms and that between cavities are studied. The influences of detuning on GQD dynamics are discussed. The results obtained by the numerical method show that GQD between atoms is strengthened with the increase of the detuning. Contrarily, GQD between cavities is weakened with the increase of the detuning. [ABSTRACT FROM AUTHOR]

Existing structures can be retrofitted against earthquakes with tuned sloshing water dampers (TSWD). These dampers can be incorporated in the structure as displacement response reduction devices for avoiding failure of masonry panels while ensuring their structural function as diagonal struts. The proposal of retrofitting for an existing four story building with TSWDs has been examined through simulated experiments on a reduced scale model of the structure mounted with actual size TSWD. The effectiveness of the single frequency TSWD systems, optimally designed for response control of accurately assessed structures, against well-defined excitations, has been substantiated. Experiments have been conducted with multi-frequency TSWD systems for approximately assessed structures against broadband excitations. The multi-frequency sloshing water damper system exhibited a comparatively robust performance against broadband excitations for a reasonable range of structural frequencies. A retrofitting scheme for the structure has been proposed with multi-frequency TSWD systems. [ABSTRACT FROM AUTHOR]