bluuebunny/crossref_metadata_2025 huggingface dataset:
Generating acoustic signals of varying intensities via modulating continuous-wave lasers scanning in air
Authors: Tong Guodong , Xia Jun , Zhong Hanfeng , Liu Shu , Wu Jun , Zhao Weiqian , Wu Zhihai , Zhang Hao , Dong Chengkun , Du Bintao
Published: January 2022

This report describes the generation of acoustic signals via laser-interference-based heating. Sound signals of varying intensities were generated by modulating two continuous-wave (CW) laser beams interfering in air. In this study, we discovered that the acoustic signals generated by two spatial-frequency-modulated CW lasers scanning in air are significantly stronger than those of a single CW laser. The intensity of photoacoustic signals is proportional to the diameter of the laser beam. Furthermore, our investigation showed that modulating the spatial frequency of the two laser beams can change the intensity of the acoustic signal. In addition, we found that the two beams stack better against a single beam when scanned vertically in three dimensions.
Self-compression of a high-intensity laser pulse in a double-ionizing gas
Authors: Jain Arohi , Gupta Devki Nandan , Kumar Saurabh
Published: January 2022

The self-compression and spatiotemporal evolution of a Gaussian laser pulse propagating in a double-ionized helium gas are investigated. The numerical model is formulated by solving the nonlinear Schrödinger equation using the paraxial like approach. The beam width parameter and pulse width parameter are estimated to investigate the laser pulse advancement in a tunnel ionizing gas. Transverse focusing and longitudinal compression are examined by characterizing the beam spot size in space and time, incorporating the gas ionization processes, relativistic mass variation, and ponderomotive effects. The results show that the inclusion of laser-induced double ionization of helium gas modifies the plasma density, which significantly affects the laser pulse evolution. For intense laser pulse, relativistic-ponderomotive nonlinearity enhances the pulse compression and consequently the self-focusing of the laser pulse. The compression mechanism and the localization of the pulse intensity both are boosted by the modified electron density via a dielectric function. At a helium gas pressure of 1.4 bar, we observed that 100 fs long laser pulse with intensity I0=8.5×1016 W/cm2 is compressed to 20 fs and the initial laser spot size 10 μm focused to 2 μm. These results promise to be a method for the generation of table-top light sources for ultrafast high-field physics and advanced optics.
Research method of pressure relief and permeability enhancement in low permeability coal seam: A review
Authors: Zhou Xihua , Li Xianlin , Bai Gang , Chai Lu , Wang Yumeng , Xiao Mufeng , Xia Shiyang
Published: January 2022

Gas drainage can prevent accidents such as coal and gas outbursts and gas explosions, which is of great significance for coal mine safety production. The level of permeability directly determines the effect of gas drainage. Therefore, experts and scholars in related fields have conducted extensive research with regard to adopting different measures to increase the permeability of coal and thereby improve the efficiency of gas drainage. However, in analyzing, comparing, and summarizing the advantages, disadvantages, and adaptability of various methods, there are few review studies in the literature. First, this Review investigates the principles, processes, and effects of different methods and finds that each method has its own specific application conditions and limitations. Simultaneously, it classifies different stimulation methods according to the principle of stimulation, which are mainly divided into physical stimulation methods, chemical stimulation methods, microbial stimulation methods, and thermal stimulation methods. Then, for better field applications, this Review investigates emphatically these methods that are currently popular but still in the laboratory stage, such as acidification stimulation and freeze–thaw stimulation, and analyzes the experimental methods, principles, experimental effects, influencing factors, etc. Permeability represents the flow capacity of gas in porous media and thereby affects the efficiency of gas extraction. Therefore, this Review summarizes the influencing factor of permeability. Finally, this Review discusses the aspect that needs to be perfected and improved for different methods and points out the problems and possible development directions in the future.
Electron losses in hypersonic flows
Authors: Parent B. , Thoguluva Rajendran P. , Omprakas A.
Published: January 2022

The first comprehensive study of electron gains and losses in hypersonic air flows including the full coupling between non-neutral plasma sheaths and quasi-neutral plasma flows is presented here. This is made possible by the use of advanced numerical methods that overcome the stiffness associated with plasma sheaths. The coupling between the sheaths, the electron temperature in non-equilibrium, and the ambipolar diffusion within quasi-neutral plasma flows is found to be critical to accurately predict electron losses and, thus, the plasma density around hypersonic vehicles. This is because electron cooling arising from the non-neutral sheaths significantly affects the electron temperature everywhere in the plasma and, therefore, the electron temperature-dependent loss processes of ambipolar diffusion and dissociative recombination. The results obtained show that electron loss to the surface due to catalyticity dominates over electron loss within the plasma due to dissociative recombination either (i) at high altitudes where the dynamic pressure is low, (ii) at low Mach number, or (iii) when the vehicle has a sharp leading edge.
Individuals with adverse childhood experiences explore less and underweight reward feedback
Authors: Lloyd Alex , McKay Ryan Thomas , Furl Nicholas
Published: January 2022

Significance

Adverse childhood experiences (ACEs) are extreme stressors that have a profound impact on cognitive development. Using an explore/exploit foraging paradigm, we demonstrate that ACEs are associated with reduced exploration, leading these individuals to accumulate fewer rewards from their environment. Using computational modeling, we identify that reduced exploration is associated with ACE-exposed individuals underweighting reward feedback, which highlights a cognitive mechanism that may link childhood trauma to the onset and maintenance of psychopathology.
Cryptochrome proteins regulate the circadian intracellular behavior and localization of PER2 in mouse suprachiasmatic nucleus neurons
Authors: Smyllie Nicola J. , Bagnall James , Koch Alex A. , Niranjan Dhevahi , Polidarova Lenka , Chesham Johanna E. , Chin Jason W. , Partch Carrie L. , Loudon Andrew S. I. , Hastings Michael H.
Published: January 2022

Significance

The suprachiasmatic nucleus (SCN), the master circadian clock of the mammalian brain, coordinates cellular clocks across the organism to regulate daily rhythms of physiology and behavior. SCN timekeeping pivots around transcriptional/translational feedback loops whereby PERIOD (PER) and CRYPTOCHROME (CRY) proteins associate and enter the nucleus to inhibit their own expression. The individual and interactive behaviors of PER and CRY and the mechanisms that regulate them are poorly understood. We combined fluorescence imaging of endogenous PER2 and viral vector–expressed CRY in SCN slices and show how CRYs, acting via their C terminus, control nuclear localization and mobility of PER2 to dose-dependently initiate SCN timekeeping and control its period. Our results reveal PER and CRY interactions central to the SCN clockwork.
Yeast cells actively tune their membranes to phase separate at temperatures that scale with growth temperatures
Authors: Leveille Chantelle L. , Cornell Caitlin E. , Merz Alexey J. , Keller Sarah L.
Published: January 2022

Significance

Phase separation in membranes creates domains enriched in specific components. To date, the best example of micrometer-scale phase separation in the membrane of an unperturbed, living cell occurs in a yeast (
Saccharomyces cerevisiae
) organelle called the vacuole. Recent studies indicate that the phases are functionally important, enabling yeast survival during periods of stress. We discovered that yeast regulate this phase transition; the temperature at which membrane components mix into a single phase is ∼15 °C above the growth temperature. To maintain this offset, yeast may tune the level of ergosterol (a molecule that is structurally similar to cholesterol) in their membranes. Surprisingly, depleting sterols in vacuole membranes causes them to phase separate, in contrast to previous assumptions.
Ca
2+
leak through ryanodine receptor 1 regulates thermogenesis in resting skeletal muscle
Authors: Meizoso-Huesca Aldo , Pearce Luke , Barclay Christopher J. , Launikonis Bradley S.
Published: January 2022

Significance

The evolution of mammals to use skeletal muscle as a source of heat allowed them to spread to all parts of the globe. The generation of heat requires increased adenosine triphosphate (ATP) hydrolysis in the resting muscle in a regulated manner, but how this mechanism works is unknown. The results suggest that mammals increase their RyR1 Ca
2+
leak rate to amplify a basal ATP turnover rate at the sarcoplasmic reticulum Ca
2+
pump that is higher than that of lower vertebrates. Muscle-based thermogenesis allows regulation of body temperature that is essential for life in mammals and provides a potential pathway for manipulating body weight or temperature by altering metabolic rate.
Carcinomas assemble a filamentous CXCL12–keratin-19 coating that suppresses T cell–mediated immune attack
Authors: Wang Zhikai , Moresco Philip , Yan Ran , Li Jiayun , Gao Ya , Biasci Daniele , Yao Min , Pearson Jordan , Hechtman Jaclyn F. , Janowitz Tobias , Zaidi Raza M. , Weiss Matthew J. , Fearon Douglas T.
Published: January 2022

Significance

Carcinomas resist immunotherapy because T cells are absent from nests of cancer cells. The chemokine/chemokine receptor system, which regulates the migration of immune cells, is a candidate for this impaired intratumoral accumulation of T cells. Cancer cells in human pancreatic, colorectal, and breast cancers are coated with the chemokine CXCL12 in the form of covalent heterodimers with keratin-19. This CXCL12 coating was investigated using a mouse model of pancreatic cancer that replicates the immunological characteristics of human cancer. Mouse pancreatic cancer cells without the CXCL12 coating formed tumors that did not exclude T cells and responded to anti–PD-1 antibody treatment. Thus, the ability of cancer cells to coat themselves with CXCL12 may contribute to resistance to immunotherapy.
Cellular and molecular architecture of submucosal glands in wild-type and cystic fibrosis pigs
Authors: Yu Wenjie , Moninger Thomas O. , Thurman Andrew L. , Xie Yuliang , Jain Akansha , Zarei Keyan , Powers Linda S. , Pezzulo Alejandro A. , Stoltz David A. , Welsh Michael J.
Published: January 2022

Significance

Submucosal glands secrete antimicrobial proteins and mucus into the airway lumen to protect the lung by killing inhaled and aspirated pathogens and clearing them from the lung. They can also contribute to several lung diseases, including the genetic disease cystic fibrosis. To better understand their structure and function, we isolated and studied submucosal glands from newborn pigs. Normal and cystic fibrosis submucosal glands were similar, suggesting that disease is due to loss of anion secretion rather than an intrinsic cell defect. By identifying submucosal gland cell types and the messenger RNA they express, the data aid understanding of submucosal gland function and provide a baseline for learning how environmental and genetic challenges contribute to lung disease.
Psycho-environmental processes of hospital design and their role during the COVID-19 pandemic (Procesos psicoambientales del diseño de hospitales y su implicación durante la pandemia por COVID-19)
Authors: Sevillano-Triguero Verónica , Estrada-Arráez Silvia
Published: January 2022

Despite the popularity of the humanization movement in healthcare environments, there has been no systematic implementation of design changes aimed at reducing the negative effects of hospital environments. This article reviews the contributions made by psycho-environmental research about the psycho-social implications of design for users’ health and well-being in the areas of healthcare, patient engagement, social interaction, spatial orientation and environmental stress. It also proposes recommendations for spatial design regarding the dual function of hospitals as a place of care for patients and a place of work for staff members. Finally, it discusses the amplification of the negative effects of hospital settings during the COVID-19 pandemic. This review provides a basic guide to the environmental effects of hospitals aimed at health professionals with a view to improving healthcare.
Angiotensin II enhances group 2 innate lymphoid cell responses via AT1a during airway inflammation
Authors: Liu Gaoyu , Chen Yingying , Wang Ying , Deng Xiaohui , Xiao Qiang , Zhang Lijuan , Xu Haixu , Han Xu , Lei Aihua , He Juan , Li Xing , Cao Yingjiao , Zhou Pan , He Chunhui , Wu Peiqiong , Jiang Wenhui , Tan Meizheng , Chen Chun , Yang Quan , Lu Liwei , Deng Kai , Yao Zhi , Zhou Jie
Published: January 2022

Group 2 innate lymphoid cells (ILC2s) have emerged as critical mediators in driving allergic airway inflammation. Here, we identified angiotensin (Ang) II as a positive regulator of ILC2s. ILC2s expressed higher levels of the Ang II receptor AT1a, and colocalized with lung epithelial cells expressing angiotensinogen. Administration of Ang II significantly enhanced ILC2 responses both in vivo and in vitro, which were almost completely abrogated in AT1a-deficient mice. Deletion of AT1a or pharmacological inhibition of the Ang II–AT1 axis resulted in a remarkable remission of airway inflammation. The regulation of ILC2s by Ang II was cell intrinsic and dependent on interleukin (IL)-33, and was associated with marked changes in transcriptional profiling and up-regulation of ERK1/2 phosphorylation. Furthermore, higher levels of plasma Ang II correlated positively with the abundance of circulating ILC2s as well as disease severity in asthmatic patients. These observations reveal a critical role for Ang II in regulating ILC2 responses and airway inflammation.
Effects of single-photon double photoionization and direct double Auger decay on K-shell ionization kinetics of Ar atoms interacting with XFEL pulses
Authors: Li Yongjun , Gao Cheng , Zeng Jiaolong , Yuan Jianmin
Published: January 2022

In studies investigating the interaction of matter with ultraintense, ultrashort x-ray free electron laser (XFEL) pulses, the evolution kinetics are generally described by directly solving a time-dependent rate equation that considers single-photon and single-electron processes. In the present study, we show the effects of single-photon double photoionization and direct double Auger decay in the K-shell ionization kinetics of XFELs interaction with argon atoms. Because a huge number of coupled transition channels are present in the K-shell ionization, we develop a Monte Carlo method to simulate the complex ionization kinetic processes and give the level population evolution of ions and charge state distribution (CSD). The K-shell-dominated ionization dynamics of Ar irradiated by XFEL pulses with photon energies of 5000, 5500 and 6500 eV are investigated and compared with available experimental observations of the CSD. The results show that the population fractions of Ar5+, Ar6+ and Ar9+ are increased by 78%, 152% and 144%, respectively, by these higher-order processes at a photon energy of 5000 eV. Including the direct double-electron processes, the predicted CSDs are in better agreement with the experiments carried out at the photon energies of 5000, 5500 and 6500 eV. It is expected that the developed theoretical formalism can be used to more accurately calibrate the beam profile and intensity of XFELs.
Demonstrating the connection between uniform circular motion and simple harmonic motion with a 3D-printed model
Authors: Lazos Panagiotis , Kyriazopoulos Nikolaos , Nezis Anastasios
Published: January 2022

The simple harmonic motion (SHM) is the simplest type of oscillatory motion. It is a key topic in most High School Physics curriculum with a rather demanding mathematical background for the students. A quite common approach for a better understanding of the motion is to visualize SHM as a projection of a uniform circular motion onto one axis. In this paper, we propose an experimental layout, which uses a specially designed object executing a uniform circular motion, in order to demonstrate the relationship between the changes in value and orientation of both the velocity and the acceleration vectors of its shadow that performs SHM. This idea was originally introduced in the second quarter of the 20th century and nowadays we combine it with the modern possibilities offered by 3D printing technology.
Analysis of respiratory kinematics: a method to characterize breaths from motion signals
Authors: Ashe William B , Innis Sarah E , Shanno Julia N , Hochheimer Camille J , Williams Ronald D , Ratcliffe Sarah J , Moorman J Randall , Gadrey Shrirang M
Published: January 2022

Objective.Breathing motion (respiratory kinematics) can be characterized by the interval and depth of each breath, and by magnitude-synchrony relationships between locations. Such characteristics and their breath-by-breath variability might be useful indicators of respiratory health. To enable breath-by-breath characterization of respiratory kinematics, we developed a method to detect breaths using motion sensors.Approach.In 34 volunteers who underwent maximal exercise testing, we used 8 motion sensors to record upper rib, lower rib and abdominal kinematics at 3 exercise stages (rest, lactate threshold and exhaustion). We recorded volumetric air flow signals using clinical exercise laboratory equipment and synchronized them with kinematic signals. Using instantaneous phase landmarks from the analytic representation of kinematic and flow signals, we identified individual breaths and derived respiratory rate (RR) signals at 1 Hz. To evaluate the fidelity of kinematics-derived RR, we calculated bias, limits of agreement, and cross-correlation coefficients (CCC) relative to flow-derived RR. To identify coupling between kinematics and flow, we calculated the Shannon entropy of the relative frequency with which flow landmarks were distributed over the phase of the kinematic cycle.Main Results.We found good agreement in the kinematics-derived and flow-derived RR signals [bias (95% limit of agreement) = 0.1 (± 7) breaths/minute; CCC median (IQR) = 0.80 (0.48–0.91)]. In individual signals, kinematics and flow were well-coupled (entropy 0.9–1.4 across sensors), but the relationship varied within (by exercise stage) and between individuals. The final result was that the flow landmarks did not consistently localize to any particular phase of the kinematic signals (entropy 2.2–3.0 across sensors).Significance.The Analysis of Respiratory Kinematics method can yield highly resolved respiratory rate signals by separating individual breaths. This method will facilitate characterization of clinically significant breathing motion patterns on a breath-by-breath basis. The relationship between respiratory kinematics and flow is much more complex than expected, varying between and within individuals.
Memristor-based time-delay hyperchaotic system with circuit simulation and image encryption
Authors: Sun Shuqi , Shi Hang , Duan Shukai , Wang Lidan
Published: January 2022

In present context, researchers have only found that memristor-based time-delay (MBTD) chaotic systems have rich dynamic behavior, but there are still many shortcomings in analyses and applications of MBTD chaotic systems. In this paper, relying on a memristor-based 4D chaotic system, by introducing delay parameters into this system, we not only find that the Lyapunov exponents (LEs) of the system change from one positive to multiple positive, i.e., the system changes from chaotic to hyperchaotic. And the coexistence of the system becomes more obvious. Although the circuit design of the delayed chaotic system is complex, the circuit implementation in Multisim is still given in this work. Ultimately, a novel digital image encryption algorithm based on this system is explained in details by introducing a hash algorithm. The proposed encryption algorithm, with strong robustness to external interference, good key sensitivity and good plaintext sensitivity, can handle images of different shapes, can effectively implement plaintext image encryption, and can resist differential attacks. All of the above further illustrate the advantages of the encryption algorithm and good randomness of the 4D MBTD hyperchaotic system.
Room temperature deposited silver oxide films by dc magnetron sputtering with high sputtering power: effect of deposition time on microstructure, electrical and optical properties
Authors: Gao Xiaoyong , Li Binqi , Liu Shuaiyang
Published: January 2022

A series of non-stoichiometric p-type silver oxide (AgxO) films are room temperature deposited on glass substrates at different deposition time (td) by dc magnetron sputtering with high sputtering power. The evolution in component and the change in electrical and optical properties of the films with td are studied by XRD, SEM, EDS, visible-infrared spectroscopy and Hall data. The p-type conduction of cubic AgO and Ag2O phases is also proposed in mechanism. The evolution in component from AgO to almost Ag2O and the change in microstructure with td are caused by the thermal decomposition of AgO phase induced by high sputtering power. The film’s absorption edge firstly redshifts from 2.8 to 2.3 eV with increase of td from 2 min to 15 min, and then is suddenly reduced to 1.25 eV of cubic phase Ag2O at 20 min td. The phases AgO and Ag2O both have p-type conduction characteristics, mainly due to the Ag vacancies and O vacancies, respectively. The free carrier concentration and the resistivity of the films are both increased and reduced with increase of td. The AgxO film with 15 min td is the highest in p-type conduction ability due to the highest free carrier concentration and mobility, and thus is capable of being the candidate of hole-transporting layer materials of perovskite solar cells.
Sterile neutrino dark matter in a U(1) extension of the standard model
Authors: Iwamoto Sho , Seller Károly , Trócsányi Zoltán
Published: January 2022

We explore the parameter space of a U(1) extension of the standard model — also called the super-weak model — from the point of view of explaining the observed dark matter energy density in the Universe. The new particle spectrum contains a complex scalar singlet and three right-handed neutrinos, among which the lightest one is the dark matter candidate. We explore both freeze-in and freeze-out mechanisms of dark matter production. In both cases, we find regions in the plane of the super-weak coupling vs. the mass of the new gauge boson that are not excluded by current experimental constraints. These regions are distinct and the one for freeze-out will be explored in searches for neutral gauge boson in the near future.
Black holes in f(T,B) gravity: exact and perturbed solutions
Authors: Bahamonde Sebastian , Golovnev Alexey , Guzmán María-José , Said Jackson Levi , Pfeifer Christian
Published: January 2022

Spherically symmetric solutions of theories of gravity built one fundamental class of solutions to describe compact objects like black holes and stars. Moreover, they serve as starting point for the search of more realistic axially symmetric solutions which are capable to describe rotating compact objects. Theories of gravity that do not possess spherically symmetric solutions which meet all observational constraints are easily falsified. In this article, we discuss classes of exact and perturbative spherically symmetric solutions in f(T,B)-gravity. The perturbative solutions add to the ones which have already been found in the literature, while the exact solutions are presented here for the first time. Moreover, we present general methods and strategies, like generalized Bianchi identities, to find spherically solutions in modified teleparallel theories of gravity.
Non-universal Fermi polaron in quasi two-dimensional quantum gases
Authors: Shi Yue-Ran , Chen Jin-Ge , Gao Kui-Yi , Zhang Wei
Published: January 2022

We consider an impurity problem in a quasi-two-dimensional Fermi gas, where a spin-down impurity is immersed in a Fermi sea of N spin-up atoms. Using a variational approach and an effective two-channel model, we obtain the energy for a wide range of interaction strength and for various different mass ratios between the impurity and the background fermion in the context of heteronuclear mixture. We demonstrate that in a quasi-two-dimensional Fermi gas there exists a transition of the ground state from polaron in the weakly interacting region to molecule in the strongly interacting region. The critical interaction strength of the polaron–molecule transition is non-universal and depends on the particle density of the background Fermi sea. We also investigate the excited repulsive polaron state, and find similar non-universal behavior.
Effect of surface plasmon coupling with radiating dipole on the polarization characteristics of AlGaN-based light-emitting diodes
Authors: Li Yi , Ge Mei , Wang Meiyu , Zhu Youhua , Guo Xinglong
Published: January 2022

The optical polarization characteristics of surface plasmon (SP) coupled AlGaN-based light emitting diodes (LEDs) are investigated theoretically by analyzing the radiation recombination process and scattering process respectively. For the Al0.5Ga0.5N/Al/Al2O3 slab structure, the relative intensity of TE-polarized and TM-polarized spontaneous emission (SE) rate into the SP mode obviously depends on the thickness of the Al layer. The calculation results show that TM dominated emission will be transformed into TE dominated emission with the decrease of the Al thickness, while the emission intensities of both TE/TM polarizations will decrease significantly. In addition, compared with TM polarized emission, TE polarized emission is easier to be extracted by SP coupling. For the Al0.5Ga0.5N/Al nano-particle structure, the ratio of transmittance for TE/TM polarized emission can reach ∼ 3.06, while for the Al free structure, it is only 1.2. Thus, the degree of polarization of SP coupled LED can be improved by the reasonable structural design.
Bandgap evolution of Mg3N2 under pressure: Experimental and theoretical studies
Authors: Wu Gang , Wang Lu , Bao Kuo , Li Xianli , Wang Sheng , Xu Chunhong
Published: January 2022

Wide bandgap semiconductors are crucially significant for optoelectronic and thermoelectric device applications. Metal nitride is a class of semiconductor material with great potential. Under high pressure, the bandgap of magnesium nitride was predicted to grow. Raman spectra, ultra-violet-visible (UV-Vis) absorption spectra, and first-principles calculations were employed in this study to analyze the bandgap evolution of Mg3N2. The widening of the bandgap has been first detected experimentally, with the gap increasing from 2.05 eV at 3 GPa to 2.88 eV at 47 GPa. According to the calculation results, the enhanced covalent component is responsible for the bandgap widening.
Effect of crystallographic orientations on transport properties of methylthiol-terminated permethyloligosilane molecular junction
Authors: Wang Ming-Lang , Zhang Bo-Han , Zhang Wen-Fei , Tian Xin-Yue , Zhang Guang-Ping , Wang Chuan-Kui
Published: January 2022

The understanding of the influence of electrode characteristics on charge transport is essential in the field of molecular electronics. In this work, we investigate the electronic transport properties of molecular junctions comprising methylthiol-terminated permethyloligosilanes and face-centered crystal Au/Ag electrodes with crystallographic orientations of (111) and (100), based on the ab initio quantum transport simulations. The calculations reveal that the molecular junction conductance is dominated by the electronic coupling between two interfacial metal–S bonding states, which can be tuned by varying the molecular length, metal material of the electrodes, and crystallographic orientation. As the permethyloligosilane backbone elongates, although the σ conjugation increases, the decreasing of coupling induced by the increasing number of central Si atoms reduces the junction conductance. The molecular junction conductance of methylthiol-terminated permethyloligosilanes with Au electrodes is higher than that with Ag electrodes with a crystallographic orientation of (111). However, the conductance trend is reversed when the electrode crystallographic orientation varies from (111) to (100), which can be ascribed to the reversal of interfacial coupling between two metal–S interfacial states. These findings are conducive to elucidating the mechanism of molecular junctions and improving the transport properties of molecular devices by adjusting the electrode characteristics.
helicity form factors and the

decays *
Authors: Cheng Wei , Zhang Yi , Zeng Long , Fu Hai-Bing , Wu Xing-Gang
Published: January 2022

In this paper, we calculate the

helicity form factors (HFFs) up to twist-4 accuracy by using the light-cone sum rules (LCSR) approach. After extrapolating those HFFs to the physically allowable

region, we investigate the

-meson two-body decays and semi-leptonic decays

, where

stand for light pseudoscalar and vector mesons, respectively. The branching fractions can be derived using the CKM matrix element and the

lifetime from the Particle Data Group, and we obtain

,

,

,

,

and

. We then obtain

and

, which agree with the LHCb measured value within

-error. We also obtain

, which like other theoretical predictions, is consistent with the LHCb measured value within

-error. These imply that the HFFs under the LCSR approach are also applicable to the

meson two-body decays and semi-leptonic decays

, and the HFFs obtained using LCSR in a new way implies that there may be new physics in the

semi-leptonic decays.
Generating long-term sub-hourly wind speed time series by coupling mesoscale models with full-scale spectra
Authors: Schillebeeckx David , Leroy Grégoire
Published: January 2022

Time series-based wind studies are gaining more and more interest and importance within the wind resource community. Benefits of such time series-based analysis being, among others, more accurate production and loss estimations, better representation of ramp-up and extreme events, and improvements in the dimensioning of energy storage systems. While mesoscale Numerical Weather Prediction (NWP) models can simulate long-term winds that capture non-stationary weather patterns, it is known that they are not able to properly resolve sub-scale processes leading to a smoothing effect. Recent studies presented spectral models that describe the full atmospheric spectrum of boundary layer winds which connect the microscale turbulent movements to the large, mesoscale fluctuations. In this work, mesoscale simulations from the Weather Research and Forecasting (WRF) model are coupled with stochastic turbulence simulations using state-of-the-art full-scale boundary-layer spectra to efficiently bridge the spectral gap between the mesoscale and the turbulence fluctuations, without requiring any local measurements nor expensive CFD simulations. The study provides a practical step-by-step approach to generate long wind speed time series at high sampling rate at any desired location and height.
Investigation of the Measurability of Selected Damage to Supporting Structures of Wind Turbines
Authors: Rupfle J , Emiroglu A , Grosse C U
Published: January 2022

The present work deals with a measurability study of damage to supporting structures of wind turbines. The examined hybrid tower consists of a prestressed concrete part with an attached steel section on top. Principal focus is on developing a data preprocessing and analysis concept aiming to investigate the measurability of the two selected failure cases missing pretension of tendons and fatigue based change of Young’s modulus in reinforcement concrete. A simulation deduced out of real world mass and thrust forces provides a comparison with measured data based tower displacements, natural frequencies and mode shapes. The measurability of given deviations is investigated by means of virtual sensors, derived from the measurement setup of a test facility measuring acceleration, velocity, displacement and strain on different positions of the wind turbine tower, aiming the development of detection methods of such cases of damage for condition monitoring systems. The simulation input can be given by strain-based external forces or vibration-based displacements.
Developing a long-lasting offshore wind business case towards a Dutch decarbonised energy system by 2050
Authors: Krishna Swamy S , Gonzalez-Aparicio I , Chrysochoidis-Antsos N
Published: January 2022

The integration of large-scale offshore wind power in the energy system will have a major effect on electricity markets. It may lead to large market price volatility due to the inherent variability of wind energy in terms of power fluctuations, forecast errors and insufficient flexibility on the demand side. This study models future business cases for offshore wind farms in two reference national scenarios for the Netherlands, namely NECP2030 and TRANSFORM. Results show that the value of offshore wind in 2030, according to NECP scenario is 39.9 €/MWh, and that electricity price in the TRANSFORM scenario, which considers aggressive development towards a sustainable economy, is a high 104 €/MWh by 2050. To consider ways of improving the return on investment for offshore wind farms in future markets, an optimisation problem is defined, where the wind farm has the choice to either sell the generated electricity to the spot market or to an electrolyser. Results show a potential advantage in using an electrolyser to produce green hydrogen for offshore wind farms, with net profit of 41.4 M€, compared to when offshore wind farms sell electricity solely to the spot market, where the profits are 36 M€.
Offshore wind farm wake modelling using deep feed forward neural networks for active yaw control and layout optimisation
Authors: Anagnostopoulos S , Piggott MD
Published: January 2022

Offshore wind farm modelling has been an area of rapidly increasing interest over the last two decades, with numerous analytical as well as computational-based approaches developed, in an attempt to produce designs that improve wind farm efficiency in power production. This work presents a Machine Learning (ML) framework for the rapid modelling of wind farm flow fields, using a Deep Neural Network (DNN) neural network architecture, trained here on approximate turbine wake fields, calculated on the state-of-the-art wind farm modelling software FLORIS. The constructed neural model is capable of accurately reproducing single wake deficits at hub-level for a 5MW wind turbine under yaw and a wide range of inlet hub speed and turbulence intensity conditions, at least an order of magnitude faster than the analytical wake-based solution method, yielding results with 1.5% mean absolute error. A superposition algorithm is also developed to construct flow fields over the whole wind farm domain by superimposing individual wakes. A promising advantage of the present approach is that its performance and accuracy are expected to increase even further when trained on high-fidelity CFD or real-world data through transfer learning, while its computational cost remains low.
Deriving an experimental and analytical relation between the core and fiber temperatures of a 3P XLPE cable
Authors: Callewaert Manly , Vanthillo Roel , Fojtek (Marlinks) Christian , Mampaey (Elia) Bart
Published: January 2022

Every submarine power cable contains a fiber-optic assembly. Most windfarms have a distributed temperature sensing (DTS) device for continuous temperature monitoring. Using real-time thermal rating (RTTR) the performance of subsea cables can be increased or a less expensive cable can be installed.

The experiments aimed to establish the relation between the fiber and core (or conductor) temperatures in the cable. Fiber temperature was obtained using a DTS interrogator; thermocouples installed in the conductors yielded the core temperature data. The cable used in this test was a 20 meter-long 1800 mm2, 1000 A export cable.

These experiments validated a new RTTR model proposed by Marlinks: a thermal RC-ladder model based on finite-element (FEM) calculations. Better suited to the complexity of the spacer geometry and existence of the fiber node, the Marlinks-developed model is considered to be more accurate than the industry standard.
Offshore Wind-to-Hydrogen Production Plant Integrated with an Innovative Hydro-Pneumatic Energy Storage Device
Authors: Settino J , Farrugia R N , Buhagiar D , Sant T
Published: January 2022

One of the main technical challenges of wind-to-hydrogen production plants is to couple intermittent and variable renewable power sources, such as wind turbines, with an electrolyser. Most hydrogen production concepts rely on electrical storage to smoothen the power input to the electrolyser. In this study, the use of a hydro-pneumatic energy storage system is proposed as an interface between the green, fluctuating electricity supply and the electrolyser. The performance of the proposed solution is analysed and compared to that of a conventional offshore wind-to-hydrogen production plant in order to identify potential advantages and drawbacks. The results of the simulations show that the FLASC energy storage system provides a stabilized, yet green power supply. Short-term fluctuations of the power input to the electrolyser can be avoided. A 70% reduction of the On/Off cycles can be obtained. Moreover, if compared to an offshore wind-to-hydrogen production plant with no storage there is no substantial difference in terms of hydrogen production observed over the analysed period of one year in spite of a 70% round-trip efficiency of the energy storage device.
Influence of initial particle configuration upon sphericity of shock loaded density interface in SPH modelling of Richtmyer-Meshkov instability
Authors: Sapozhnikov Filipp A , Rykovanov Vasiliy S
Published: January 2022

The Richtmyer-Meshkov Instability (RMI) occurs when a perturbed interface between two fluids of different densities undergoes impulsive acceleration by, for example, a shock wave. Its study is important for gaining better understanding of processes governing inertial confinement fusion where a spherical solid deuterium-tritium (DT) capsule filled with the DT gas is compressed by a powerful laser [1]. The imploding shock moving to the center of the spherical shell causes the RMI to form on its inner surface due to a large density difference between solid and gaseous DT phases, which leads to a rapid growth of initially present randomperturbations. Usually, the density interface consists of random perturbations (e.g., surface roughness, machining inaccuracies, etc.) which initially grow linearly before nonlinear effects emerge. To improve reliability of shock-driven flow simulations, it is necessary to understand the factors which inuence the RMI growth. Our work aims to find the best initial particle configuration that does not introduce artificial perturbations of the spherical density interface. The shocked interface must preserve spherical symmetry if no perturbations are applied. In order to reduce the number of simulated particles in calculation, it is necessary to adapt spatial resolution, i.e., to increase the concentration of particles in target regions.
Shock induced melting of sapphire
Authors: Ostrik A , Nikolaev D
Published: January 2022

The method for calculation the melting curves of crystalline bodies based on the Debye model of heat capacity and the Lindemann melting rule is proposed. Hugoniot shock adiabate, determined in dynamic experiments and thermophysical characteristics of the substance under normal conditions are used as input data. Mathematically, the calculation of the melting curveis reduced to the Cauchy problem for a system of ordinary differential equations. This system is solved numerically by the Runge-Kutta method. Using the proposed method, the melting curves of copper, silver, gold, and sapphire at high pressures are calculated. The results obtained for copper, silver and gold were compared with available calculated and experimental data to validate the method. Experiments on shock compression of transparent sapphire sampleswere performed, using a Mach-type cumulative explosive generators. Investigated pressure range (280-1350 GPa) covered a region of shock-induced melting. The temperature of shock front was registered by fast optical pyrometer together with shock velocity. Particle velocity andpressure were obtained by impedance matching technique. Satisfactory agreement of calculatedand experimental data on temperature of melting behind the shock wave front in sapphire was obtained.
Prediction of bead geometry on filling cavities in hydroelectric turbine blades by means of robotic welding
Authors: Lázaro Plata J L , Caribé de Carvalho G , Flórez Solano E N
Published: January 2022

This paper presents a methodology of mapping the bead geometry, deposited on a fillet like joint, as a function of the input parameters of the synergic pulsed gas metal arc welding process and the welding position, to allow the planning of repairing hydroelectric turbine runner blades by means of robotic welding. The challenges of automating the repair process; further, to choosing the best welding parameters, include the definition of the path that the robot must follow during the metal deposition, such that it is able to fill completely the damaged blade cavity, by means of producing overlapped layers from several individual weld beads. Thus, this research focused on developing statistical prediction models that could map the geometric variations of the weld bead section as function of the input parameters (wire feed speed, welding speed and bead face rotation angle). For this purpose, the bead section was approximated by a parallelogram whose height, width and inclination angle were considered as dependent variables. Several welding trials were carried out according to a central composite experimental design and three multiple regression models were obtained. Here, the physics is used to interpret the influence of the input parameters on the output results.
Prescribed Performance Voltage Control Strategy of LC Inverter
Authors: Shi Jianqiang , Li Shuang
Published: January 2022

Aiming at the voltage tracking problem of the LC inverter, a new prescribed performance controller is proposed. In order to make the voltage tracking error converge entirely according to the trajectory described by the performance function, a new state variable is introduced referring to the integral sliding surface. The specific form of the voltage controller is obtained according to the voltage equation in the dq coordinate frame and the system stability requirement. The adopted control law is easy to implement. It does not need to adjust the parameters repeatedly so that the inverter’s steady-state and dynamic performance indicators can be close to the prescribed values. The MATLAB/Simulink platform simulation experiment verifies the feasibility and effectiveness of the proposed new prescribed performance control strategy.
Development and Efficiency Test of a 3 MVA Four-port Power Electronic Transformer
Authors: Luo Long , Li Yaohua , Li Zixin , Zhao Cong
Published: January 2022

The development of a 3 MVA four-port, i.e. 10 kV ac port, 380 V ac port, ±750 V dc port, and ±375 V dc port, power electronic transformer (PET) for an integrated energy system is described. For this four-port PET, the efficiency test is a complex problem as each port-to-port efficiencies should be tested. To solve this problem, this paper proposes a data fitting method using only the converter efficiency in each port. The experimental results show a high accuracy of the proposed testing method. The test results of this four-port PET are also analyzed and the efficiency under different power flow directions is explained.
Frequency Domain Characteristic Analysis of Fault Electrical Quantities in HVDC Transmission System
Authors: Cao Hong , Liang Ying , Yu Yue , Wang Zhengmao
Published: January 2022

The transient frequency domain characteristics of different fault electrical quantities in HVDC transmission system are studied in this paper firstly using analytical calculation. Firstly, the equivalent model of LCC converter suitable for DC system fault characteristic analysis and the equivalent model of DC line considering parameter frequency variation effect are established. On this basis, the DC system fault equivalent circuit is constructed. The frequency domain expressions of relevant electrical quantities under different DC line fault conditions are obtained according to the solution of equivalent circuit. On the basis of the frequency domain expression of fault electrical quantity, the frequency component diagram of fault electrical quantity is obtained. Finally, the frequency spectrum of fault voltage under different fault conditions is analyzed and compared.
Efficient Compression Method Based on Object Model for Massive Real-time Data in Power IOT
Authors: Hou Jixin , Zhao JingHu , Wu Zidong , Fan Ying , Wang Xiaochao , Meng Jie
Published: January 2022

With rapid development of the Internet of things (IOT) in power field, equipment of various majors began to access the smart IOT system on a large scale. In this paper, a new data compression algorithm based on object model (CABM) is proposed to solve the problems of large-scale applications of power Internet of Things, such as high-frequency transmission of large quantities, real-time short data can not be effectively compressed, resulting in low efficiency of cloud edge information transmission and serious waste of bandwidth resources. The CABM adds a compression and decompression module between the IOT management platform and the edge agent; the IOT management platform automatically generates a compression dictionary based on the object model file and saves it synchronously in the edge agent. During data transmission, both the sender and receiver complete automatic compression and decompression according to the compression dictionary. The experimental results show that for real-time message data below 1KB, the compression rate using CABM algorithm is 3-5 times higher than that using GZIP compression algorithm; and the compression time is 10-20 times lower than that using GZIP; the efficiency using CABM algorithm is 4.5 times higher than that using GZIP algorithm; that is, CABM can reduce redundant data transmission between cloud edges and improve the efficiency of cloud edge transmission.
Design and Research of Operating Repulsion Mechanism Suitable for 252kV High-Speed Breaking Circuit Breaker
Authors: Cheng Cai , Liu Yingyi , Wei Jianwei , Yuan Haiwen
Published: January 2022

This paper proposes a high-speed operating repulsive force mechanism suitable for 252kV high-voltage circuit breakers. The mechanism draws on the working principle of the electromagnetic repulsion operating mechanism of the medium voltage circuit breaker, and combines the new electromagnetic fast repulsion device with the traditional disc spring hydraulic mechanism to realize the fast action of the circuit breaker. This paper first introduces the working principle of the electromagnetic repulsion operating mechanism, and proposes the initial design scheme of the mechanism. Subsequently, the digital twin technology was used to establish the rigid-flexible coupling multi-body dynamics model of the mechanism, and the defects of the initial scheme were analyzed based on simulation. Finally, the paper optimized the design of the initial scheme and verified it by simulation. The test shows that the 252kV high-voltage circuit breaker with the improved scheme as the operating mechanism works normally and can complete the fault breaking within 20.1ms, which is twice as fast as the current products of the same type.