Energy Leakage Research Articles

Comparative analysis of SWIFT and Grid-SWIFT waveforms for improved ion excitation and isolation resolution

Miniaturized mass spectrometers, with their increasing portability and performance enhancements, play a crucial role in selectively analyzing target compounds within complex mixtures, particularly in situ environments. As part of our ongoing efforts to enhance the analytical capabilities of the custom-built "brick" mass spectrometer, this study compared and optimized methods for ion isolation using Stored Waveform Inverse Fourier Transform (SWIFT) and Grid-SWIFT waveforms. The efficacy of the SWIFT and Grid-SWIFT waveforms in selective ion isolation was investigated, and through optimization of both waveforms, improved ion isolation efficiency, and peak resolution were demonstrated by adjusting waveform duration and amplitude. The results conclusively showed that Grid-SWIFT outperforms traditional SWIFT waveforms in enhancing the isolation of target ions. Additionally, a novel simulation-based approach was developed to simulate the behavior of ion trajectories under the SWIFT and Grid-SWIFT waveforms within LIT to provide a theoretical basis for better performance of the Grid-SWIFT waveforms. Results show that longer waveform durations help reduce energy leakage, providing higher isolation efficiency. Grid-SWIFT waveforms exhibited significantly less energy leakage compared to SWIFT waveforms. Consequently, using Grid-SWIFT as isolation waveforms improved the mass spectra' intensity and resolution.

Wideband beam domain sparse Bayesian learning passive focusing localisation algorithm

AbstractTo address the challenges of large‐aperture sonar systems passive localisation, this paper proposes the application of sparse Bayesian learning (SBL) for passive target localisation in the wideband beam domain. The proposed algorithm aims to overcome the issues of massive computational requirements for two‐dimensional SBL scanning and increased localisation errors due to interference energy leakage. The wideband beam domain SBL focusing localisation algorithm is developed by constructing an azimuth‐range two‐dimensional transformation matrix to preprocess array data, which effectively reduces the computational load of SBL processing while suppressing strong interference energy leakage in passive sonar operating environments, thus improving the range resolution and parameter estimation accuracy of focusing localisation. Simulation and sea trial data analyses demonstrate the feasibility of the proposed algorithm, with results indicating its superior performance compared to existing algorithms.

A Strategy for Modeling Nonstatistical Reactivity Effects: Combining Chemical Activation Estimates with a Vibrational Relaxation Model.

The kinetics of many chemical reactions can be readily explained with a statistical approach, for example, using a form of transition state theory and comparing calculated Gibbs energies along the reaction coordinate(s). However, there are cases where this approach fails, notably when the vibrational relaxation of the molecule to its statistical equilibrium occurs on the same time scale as the reaction dynamics, whether it is caused by slow relaxation, a fast reaction, or both. These nonstatistical phenomena are then often explored computationally using (quasi)classical ab initio molecular dynamics by calculating a large number of trajectories while being prone to issues such as zero-point energy leakage. On the other side of the field, we see resource-intensive quantum dynamics simulations, which significantly limit the size of explorable systems. We find that using a Fermi's golden rule type of model for vibrational relaxation, based on anharmonic coupling constants, we can extract the same qualitative information while giving insights into how to enhance (or destroy) the bottlenecks causing the phenomena. We present this model as a middle ground for exploring complex nonstatistical behavior, capable of treating medium-sized organic molecules or biologically relevant fragments. We also cover the challenges involved, in particular quantifying the excess energy in terms of vibrational modes. Relying on readily available electronic structure methods and providing results in a simple master equation form, this model shows promise as a screening tool for opportunities in mode-selective chemistry without external control.

Electromagnetic field compensation to attenuate energy leakage in TM020 mode damped cavity

This paper discusses the TM020 mode Higher-order Mode (HOM) damped cavity, which has a higher quality factor and lower characteristic impedance than the conventional TM010 mode. The unique electromagnetic field (EMF) distribution of the TM020 mode allows for an absorber to be placed at the magnetic field wave node, protecting the working mode while suppressing the HOMs. However, the introduction of high power input couplers and other structures can cause an asymmetrical EMF distribution, leading to operating mode leakage.To address this, EMF compensation methods are applied to the high power input coupler to achieve symmetrical EMF distribution, reducing operating mode loss. Overcoupling of the high power input coupler and the resonant cavity can significantly affect local EMF distribution, causing TM020 mode asymmetry. A tab structure at the coupler port are used to compensate for coupler-induced perturbations, attenuating EMF leakage.The paper proposes electromagnetic compensation structure schemes to mitigate working mode EMF leakage. The reliability of the scheme is demonstrated by the analysis of radiofrequency performance and other aspects through simulation software.

Effects of interlayer SiO2 or Au on the performances of LNOS-SAW

Abstract Surface acoustic wave (SAW) resonators and filters based on lithium niobate (LN) or lithium tantalate crystals have been widely used in modern wireless communication systems. However, acoustic energy in these kinds of devices is lost in the substrate due to longitudinal attenuation. The enhancements of quality factor and coupling coefficient are still in demand for further applications. This work proposes a SAW based on LN thin film on a sapphire substrate (LNOS). Besides, we explored the effects of using different bonding materials on the LNOS-SAW performances. The presence of the interlayer not only plays a role in bonding but also has an impact on the performance of the resonator. Considering the compatibility of the process in this method, 2 μm-thick silicon dioxide (SiO2) or 1 μm-thick gold (Au) is designed as the interlayer. As the displacement diagrams show, the acoustic energy of the SAW with interlayer is reflected at the interface, and the energy leakage is suppressed. The simulation results show that the presence of SiO2 or Au causes a decrease in resonant frequencies of the resonators, and the effect is more pronounced with Au. Significantly, the presence of SiO2 enhances the coupling efficiency of the resonator while the Au interlayer brings a more obvious improvement in the quality factor.

A novel 4H–SiC thermal neutron detector based on a metal-oxide-semiconductor structure

Energy resolution and leakage current are two key parameters for semiconductor neutron detectors. Metal-Oxide-Semiconductor (MOS) detectors introduce an additional oxide layer compared to Schottky Barrier Diodes (SBDs) detectors in order to reduce leakage current. However, this also leads to a degradation in energy resolution due to the introduction of an additional dead layer. Therefore, optimizing the thickness of the oxide layer is important for MOS detectors. In this study, a 4H–SiC-based MOS thermal neutron detector was designed with comprehensive consideration of the oxide layer. Subsequently, a prototype of the detector was fabricated and tested. The prototype of the MOS detector achieved an nA-level leakage current under a reverse bias of −200 V. Additionally, it demonstrated good energy resolution performance in a moderated D-T neutron source test. The MOS detector was able to clearly distinguish between the two reaction channels of 10B converter events, which is consistent with the theoretical branching ratio. This work highlights the potential application of 4H–SiC-based MOS detectors for thermal neutron detection.

Topological photonic band gaps in honeycomb atomic arrays

lattice of two-level atoms coupled by the in-plane electromagnetic field may exhibit band gaps that can be opened either by applying an external magnetic field or by breaking the symmetry between the two triangular sublattices of which the honeycomb one is a superposition. We establish the conditions of band gap opening, compute the width of the gap, and characterize its topological property by a topological index (Chern number). The topological nature of the band gap leads to inversion of the population imbalance between the two triangular sublattices for modes with frequencies near band edges. It also prohibits a transition to the trivial limit of infinitely spaced, noninteracting atoms without closing the spectral gap. Surrounding the lattice by a Fabry-Pérot cavity with small intermirror spacing d < \pi/k_0d<π/k0, where k_0k0 is the free-space wave number at the atomic resonance frequency, renders the system Hermitian by suppressing the leakage of energy out of the atomic plane without modifying its topological properties. In contrast, a larger dd allows for propagating optical modes that are built up due to reflections at the cavity mirrors and have frequencies inside the band gap of the free-standing lattice, thus closing the latter.

Synchronous match-reassigning transform: A method for extracting time-varying features of planetary gearbox

Instantaneous frequency (IF) time-varying closely spaced and severe background noise can introduce fake components into the time-frequency representation (TFR) of most time-frequency analysis (TFA) methods, especially for the vibration signals of variable-speed planetary gearboxes. These fake components lead to a decrease in the readability of the TFR, making it difficult to extract the true IF. To address this issue, a new TFA method called Synchronous Match-Reassigning Transform (SMRT) is proposed. Firstly, a polynomial chirp rate with a single parameter adjustment is constructed to achieve precise matching of the IF. Secondly, a frequency reassignment operator is constructed for the fine refinement of the IF ridge of Synchronous Match-Reassigning Operator (SMRO). Finally, SMRO is combined with VKF to achieve adaptive reconstruction of the true IF and to remove fake components. The TFR of SMRT has high readability and low energy leakage. The superiority and effectiveness of this method have been verified through synthetic signals and actual signals.

A gap waveguide-based mechanically reconfigurable phase shifter for high-power Ku-band applications

This paper presents a novel design of a low-loss, reconfigurable broadband phase shifter based on groove gap waveguide (GGW) technology. The proposed phase shifter consists of a folded GGW and three bends with a few pins forming the GGW and one bend attached to a movable plate. This movable plate allows for adjustments to the folded waveguide length, consequently altering the phase of electromagnetic waves. The advantage of GGW technology is that it does not require electrical contact between different parts of a structure. Therefore, it enables the moving parts to slide freely without electromagnetic energy leakage, resulting in improved insertion loss in high-power applications. In addition, in the proposed design, the position of the input and output waveguide ports of the phase shifter remains fixed, which is advantageous from a practical point of view. As shown by measurement and simulation results, there is nearly 37% impedance bandwidth with the highest insertion loss of 0.6 dB, and the developed device has a maximum phase shift of 770° at the center frequency of 13 GHz. The phase shifter can be used for various radar and satellite applications that require phase control, such as beamforming networks and phased array antennas.

Multi-objectives occupant-centric control of thermostats and natural ventilation systems in cold climate conditions using real-time occupant-related information

Recently, Occupant-Centric Controls (OCCs) have attracted great attention. Many studies have applied OCCs to mechanical ventilation systems, while natural ventilation systems have gathered much less attention. The natural ventilation effect, driven by opening windows or vents, can be effective in improving indoor air quality, however, result in a leakage of interior heating energy in winter in cold climates. Therefore, the controls of thermostats and natural ventilation systems shall be designed well so that satisfying levels of thermal comfort, air quality and energy conservation can be simultaneously guaranteed. This study proposes an OCC and applies it to thermostats and natural ventilation systems for indoor thermal comfort, air quality and heating energy management. The strategy comprises three controllers: occupancy-based on-off controller, controller of setpoint of indoor air temperature and window openness controller. First, real-time profiles of heat gains from occupants and window openness were collected by employing vision-based detection. Second, a parametric building simulation study was conducted, and then simulation data were generated to develop predictive shallow artificial neural networks for forecasting the indoor conditions and energy performance of the investigated room. Third, the performance of the proposed strategy was examined. Compared to the baselines, the control could offer a decrease in building heating loads by between 43.4% and 63.8 % and an improvement of predicted mean vote levels by 0.36–0.37. The proposed OCC could also maintain indoor CO2 concentrations below 1000 ppm for about 91 % of the studied time, while 84.2 % of the time with several peaks over 3000 ppm in the baseline cases.

Unlocking ultra-high holographic information capacity through nonorthogonal polarization multiplexing

Contemporary studies in polarization multiplexing are hindered by the intrinsic orthogonality constraints of polarization states, which restrict the scope of multiplexing channels and their practical applications. This research transcends these barriers by introducing an innovative nonorthogonal polarization-basis multiplexing approach. Utilizing spatially varied eigen-polarization states within metaatoms, we successfully reconstruct globally nonorthogonal channels that exhibit minimal crosstalk. This method not only facilitates the generation of free-vector holograms, achieving complete degrees-of-freedom in three nonorthogonal channels with ultra-low energy leakage, but it also significantly enhances the dimensions of the Jones matrix, expanding it to a groundbreaking 10 × 10 scale. The fusion of a controllable eigen-polarization engineering mechanism with a vectorial diffraction neural network culminates in the experimental creation of 55 intricate holographic patterns across these expanded channels. This advancement represents a profound shift in the field of polarization multiplexing, unlocking opportunities in advanced holography and quantum encryption, among other applications.

High-Speed Rail Multiple-Input–Multiple-Output Channel Model Based on Reconfigurable Intelligent Surface System

This paper presents a geometry-based stochastic model (GBSM) for a reconfigurable intelligent surface (RIS)-assisted multiple-input–multiple-output (MIMO) system tailored to high-speed rail environments, addressing energy leakage at space lattice points caused by the time-dependent reception direction and differing antenna array resolutions. Initially, this study explores the spatial domain feature map and spreading antenna lobe characteristics from various RIS array configurations to reshape the polarization distribution and facilitate a virtual antenna array. Subsequently, the time-dependent reception direction and position are derived by integrating the dynamics of train operations. Finally, the received signal is aligned with the polarization direction to assess the signal reception efficiency and finalize the model output. Research findings indicate that the number of RIS elements, spacing between RIS elements, and mobile relay (MR) movement characteristics significantly influence the performance of the system. Compared to existing models, the proposed model proficiently captures the effects of time-dependent receiver angle properties and RIS array configuration.

On the Applicability of Kramers–Kronig Dispersion Relations to Guided and Surface Waves

In unbounded media, the acoustic attenuation as function of frequency is related to the frequency-dependent sound velocity (dispersion) via Kramers–Kronig dispersion relations. These relations are fundamentally important for better understanding of the nature of attenuation and dispersion and as a tool in physical acoustics measurements, where they can be used for control purposes. However, physical acoustic measurements are frequently carried out not in unbounded media but in acoustic waveguides, e.g., inside liquid-filled pipes. Surface acoustic waves are also often used for physical acoustics measurements. In the present work, the applicability of Kramers–Kronig relations to guided and surface waves is investigated using the approach based on the theory of functions of complex variables. It is demonstrated that Kramers–Kronig relations have limited applicability to guided and surface waves. In particular, they are not applicable to waves propagating in waveguides characterised by the possibility of wave energy leakage from the waveguides into the surrounding medium. For waveguides without leakages, e.g., those formed by rigid walls, Kramers–Kronig relations remain valid for both ideal and viscous liquids. Examples of numerical calculations of wave dispersion and attenuation using Kramers–Kronig relations, where applicable, are presented for unbounded media and for waveguides formed by two rigid walls.

Wireless and battery-operatable IoT platform for cost-effective detection of fouling in industrial equipment

We present a novel internet of things (IoT) sensing platform that uses helical propagation paths of ultrasonic guided waves (UGWs) for structural health monitoring. This wireless sensor network comprises multiple identical sensor units that communicate with a host PC. The units have dedicated hardware to both generate and receive ultrasonic signals, as well as RF signals for use in triggering the sensors. The system was developed for monitoring and sensing pipelines and similar structures in real-time to facilitate interactive sensing. For accurate sensing with a limited number of arbitrarily scattered sensors, we obtain information from all sensor pairs and analyze helical propagation paths in addition to the commonly used shortest paths. UGWs can propagate long distances along the walls of pipelines, and their propagation velocity depends directly on the thickness of the waveguide, and is affected by energy leakage and mass loading. In this paper, we evaluated the network by utilizing it to detect fouling. The network could be adapted for further ultrasonic measurement tasks, e.g., measuring wall thicknesses or monitoring defects with pulse-echo methods.

Generation of reverse time migration dip gathers with the stabilized Poynting vector and their application in the improvement of subsalt images

Subsalt imaging is challenging with coherent noise prevalent beneath complex salt structures. The coherent noise degrades the imaging quality, making image enhancement and interpretation difficult and potentially erroneous. The dip gathers of reverse time migration (RTM) serve as an ideal domain for separating signals from coherent noise due to their distinct distributions in the dip domain. Methods utilizing the Poynting vector offer an efficient and cost-effective means to produce dip gathers. However, the presence of zero points in the Poynting vector causes instabilities in direction or angle estimation, leading to the leakage of reflection energy into false dip angles. This issue complicates the separation of desired signals from coherent noise. We address this instability by employing a stabilized Poynting vector to produce high-quality RTM dip gathers. The stabilized Poynting vector does not contain zero points within the range of wave propagation, thus mitigating the instability problem. The dip gathers generated using the stabilized Poynting vector provide a clearer and more precise depiction of signal and noise distributions, allowing us to identify the boundaries of desired signals and mute all noise outside these boundaries. Two numerical examples with a synthetic dataset and a field dataset are used to demonstrate our method's effectiveness in reducing coherent noise and improving quality of subsalt images.

Circular additions to linear systems? Exploring Norwegian households' engagement with circularity in everyday life

The circular economy (CE) has gained a prominent position in the broader literature, discourse, and policy arenas concerned with sustainable production and consumption. With roots in industrial ecology, the goal of CE is to shift away from linear ‘take-make-waste’ systems towards a regenerative system where resource input and waste, emission, and energy leakage are minimised by slowing, closing, and narrowing material and energy loops, achieved through long-lasting design, maintenance, repair, reuse, remanufacturing, refurbishing, and recycling. Household consumption plays a central role in a shift towards the CE, but the complexities of consumption in everyday life are often overlooked in CE research. This article employs a practice theoretical lens to analyse the ways in which circularity is integrated into everyday life, for what purposes and with what effects. The data material consists of qualitative interviews with residents, and municipal and voluntary actors in Asker, Norway. We find that circularity was integrated by means of excitement and mastery, practical solutions, or financial savings on particular occasions, but was not necessarily considered a significant contributor to sustainability, nor did it replace linear forms of consumption. Households carved out space for circularity that largely left spatial or temporal rhythms of everyday life, established social norms, relations, or embodied knowledge unchallenged. Rather, circularity was integrated to maintain, rationalize, or simplify existing practices while upholding the throughput of household goods and resources, or pursue goals that had little to do with reduced resource use, representing circular additions to existing linear systems.

Low-Voltage High-Frequency Lamb-Wave-Driven Micromotors.

By leveraging the benefits of a high energy density, miniaturization and integration, acoustic-wave-driven micromotors have recently emerged as powerful tools for microfluidic actuation. In this study, a Lamb-wave-driven micromotor is proposed for the first time. This motor consists of a ring-shaped Lamb wave actuator array with a rotor and a fluid coupling layer in between. On a driving mechanism level, high-frequency Lamb waves of 380 MHz generate strong acoustic streaming effects over an extremely short distance; on a mechanical design level, each Lamb wave actuator incorporates a reflector on one side of the actuator, while an acoustic opening is incorporated on the other side to limit wave energy leakage; and on electrical design level, the electrodes placed on the two sides of the film enhance the capacitance in the vertical direction, which facilitates impedance matching within a smaller area. As a result, the Lamb-wave-driven solution features a much lower driving voltage and a smaller size compared with conventional surface acoustic-wave-driven solutions. For an improved motor performance, actuator array configurations, rotor sizes, and liquid coupling layer thicknesses are examined via simulations and experiments. The results show the micromotor with a rotor with a diameter of 5 mm can achieve a maximum angular velocity of 250 rpm with an input voltage of 6 V. The proposed micromotor is a new prototype for acoustic-wave-driven actuators and demonstrates potential for lab-on-a-chip applications.

Elastic wave demultiplexer with frequency dependent topological valley Hall edge states

Valley Hall topological insulators (VHTIs) hold great promise for enhancing the manipulation of elastic wave propagation by their intrinsic topologically protected mechanism. Different from most of VHTIs designed by the deterministic Dirac degeneracy, a more flexible design of VHTIs is proposed by the accidental Dirac degeneracy to steer elastic wave propagation. Based on the accidental Dirac degeneracy, a kind of hexagonal phononic crystal is designed to independently control the topological phase transitions at different frequency ranges. Consequently, a two-channel topological demultiplexer is designed with the function of frequency separation for flexural waves, and its effectivity is verified by numerical simulations and experimental testing. Comparing with traditional designs of demultiplexers, the VHTIs-based demultiplexer possesses a series of advantages in robust performance, easy fabrication and low energy leakage, and sheds light on developing new generation of elastic wave devices.

An Improved Synchrosqueezing S-Transform and Its Application in a GPR Detection Task.

The S-transform is a fundamental time-frequency (T-F) domain analysis method in ground penetrating radar (GPR) data processing and can be used for identifying targets, denoising, extracting thin layers, and high-resolution imaging. However, the S-transform spectrum experiences energy leakage near the instantaneous frequency. This phenomenon causes frequency components to erroneously spread over a wider range, impacting the accuracy and precision of GPR data processing. Synchrosqueezing is an effective method to prevent spectrum leakage. In this work, we introduce the synchrosqueezing generalized phase-shifting S-transform (SS-GPST). Initially, it resolves the compatibility issue between the S-transform and the synchrosqueezing strategy through phase-shifting. Subsequently, the SS-GPST accomplishes spectral energy focusing and resolution enhancement via a generalized parameter and synchrosqueezing. A synthetic signal test shows that the SS-GPST excels over other methods at focusing degree, spectral resolution, and signal reconstruction accuracy and speed. In actual GPR tunnel detection data processing, we assess the adaptability of the SS-GPST from three aspects: spectral energy distribution, thin layer identification, and data denoising. The results indicate: (1) compared to other methods, the SS-GPST accurately expresses spectral components with a strong focusing degree and fewer interference components; (2) high-frequency slices of the SS-GPST accurately detect the top and bottom interfaces of a 3.0-3.5 cm reinforcement protection layer; and (3) due to fewer interference components in the SS-GPST spectrum, reconstructing GPR profiles through the SS-GPST inverse transform is an efficient denoising technique. The SS-GPST demonstrates adaptability to different data processing purposes, offers high-resolution T-F spectra, and shows potential to supersede the S-transform.

Fatigue loads compressed editing by discrete wavelet transform and optimal wavelet parameters selection algorithm

Discrete wavelet transform (DWT) can be used to edit the vehicle road load signals for accelerating durability analyses. Nevertheless, it should be noted that one of inherent deficiencies of DWT is the obvious energy leakage. This paper proposes an improved compressed editing method for vehicle road load signals, which is to achieve more accurate results, based on the energy leakage of DWT to select the optimal wavelet parameters. A wavelet parameters optimal method is proposed by investigating the severity of parameters on energy leakage. Daubechies wavelet functions with different order are performed on signals under the same decomposition level. Then, the intensity of energy leakage in wavelet components in each level is calculated and compared with adjacent levels. Thus, the optimal wavelet parameters will be extracted taking into account the time–frequency resolutions. The effectiveness of this method has been validated by numerical signal, and the optimal method is applied to a series of load signal to achieve compressed compilation.