bluuebunny/crossref_metadata_2025 huggingface dataset:
Disease mutations and phosphorylation alter the allosteric pathways involved in autoinhibition of protein phosphatase 2A
Authors: Konovalov Kirill A. , Wu Cheng-Guo , Qiu Yunrui , Balakrishnan Vijaya Kumar , Parihar Pankaj Singh , O’Connor Michael S. , Xing Yongna , Huang Xuhui
Published: June 2023

Mutations in protein phosphatase 2A (PP2A) are connected to intellectual disability and cancer. It has been hypothesized that these mutations might disrupt the autoinhibition and phosphorylation-induced activation of PP2A. Since they are located far from both the active and substrate binding sites, it is unclear how they exert their effect. We performed allosteric pathway analysis based on molecular dynamics simulations and combined it with biochemical experiments to investigate the autoinhibition of PP2A. In the wild type (WT), the C-arm of the regulatory subunit B56δ obstructs the active and substrate binding sites exerting a dual autoinhibition effect. We find that the disease mutant, E198K, severely weakens the allosteric pathways that stabilize the C-arm in the WT. Instead, the strongest allosteric pathways in E198K take a different route that promotes exposure of the substrate binding site. To facilitate the allosteric pathway analysis, we introduce a path clustering algorithm for lumping pathways into channels. We reveal remarkable similarities between the allosteric channels of E198K and those in phosphorylation-activated WT, suggesting that the autoinhibition can be alleviated through a conserved mechanism. In contrast, we find that another disease mutant, E200K, which is in spatial proximity of E198, does not repartition the allosteric pathways leading to the substrate binding site; however, it may still induce exposure of the active site. This finding agrees with our biochemical data, allowing us to predict the activity of PP2A with the phosphorylated B56δ and provide insight into how disease mutations in spatial proximity alter the enzymatic activity in surprisingly different mechanisms.
High-speed planar laser-induced fluorescence investigation of nitric oxide generated by hypersonic Mach reflections for computational fluid dynamics validation
Authors: Leonov Boris S. , Dean Tyler S. , Limbach Christopher M. , Bowersox Rodney D. , Miles Richard B.
Published: June 2023

In this article, the authors present an experimental investigation of the thermochemical relaxation regions downstream of symmetric Mach reflections generated in Mach 8.5 flows with stagnation enthalpies from 7 to 10 MJ/kg. The experiment was performed in the Hypervelocity Expansion Tunnel at the National Aerothermochemistry and Hypersonics Laboratory of Texas A&M University. The investigation focused on studying the nitric oxide morphology in the vicinity of a strong normal shock wave and shear layers. Experimental planar laser-induced fluorescence measurements at 250 kHz repetition rate with a quasi-simultaneous natural emission photography demonstrate a sufficient rejection of natural emission and reveal intricate flow structures in the shock vicinity. Steady computational fluid dynamics (CFD) flow solutions obtained with the US3D software were used to simulate laser-induced fluorescence signal levels for quantitative comparison against the experimentally acquired data. The investigation accomplished four objectives: complex flowfield visualization in the vicinity of the Mach stem with 4 μs temporal resolution, evaluation of the level of high-temperature chemistry effects introduced to the freestream by the expansion tunnel, both qualitative and quantitative CFD simulation validation, and cross-checking or introduction of fundamental properties of nitric oxide laser-induced fluorescence including absorption cross section for vibrationally excited states of nitric oxide and a collisional quenching cross section of nitric oxide by atomic nitrogen.
Topological edge states of 1D chains and index theory
Authors: Thiang Guo Chuan
Published: June 2023

We provide an elementary proof and refinement of a well-known idea from physics: a chiral-symmetric local Hamiltonian on a half-space has the same signed number of edge-localized states with energies in the bulk bandgap as its bulk winding number. The requirement of non-elementary methods to relate generic and non-generic cases is emphasized. Our hands-on approach complements a quick abstract proof based on the classical index theory of Toeplitz operators.
Spectral turbulence kinetic energy budget and scale-based velocity decomposition for turbulence in bubble plumes
Authors: Wu Huijie , Wang Binbin
Published: June 2023

We conducted a spectral analysis of the turbulence kinetic energy (TKE) budget in a bubble plume using particle image velocimetry with fluorescent particles. Our findings confirmed the hypothesis of an inverse energy cascade in the bubble plume, where TKE is transferred from small to large eddies. This is attributed to direct injection of TKE by bubble passages across a wide range of scales, in contrast to canonical shear production of TKE in large scales. Turbulence dissipation was identified as the primary sink of the bubble-produced TKE and occurred at all scales. The decomposition of velocities using the critical length scale of inter-scale energy transfer allowed us to distinguish between large- and small-scale motions in the bubble plume. The large-scale turbulent fluctuations exhibited a skewed distribution and were likely associated with the return flow after bubble passage and the velocities induced by the bubble wake. The small-scale turbulent fluctuations followed a Gaussian distribution relatively well. The large-scale motions contributed to over half of the Reynolds stresses, while there were significant small-scale contributions to the normal stresses near the plume center but not to the shear stress. The large-scale motions in the vorticity field induced a street of vertically elongated vortex pairs, while the small-scale vortices exhibited similar sizes in both horizontal and vertical directions.
Beyond independent error assumptions in large GNN atomistic models
Authors: Ock Janghoon , Tian Tian , Kitchin John , Ulissi Zachary
Published: June 2023

The calculation of relative energy difference has significant practical applications, such as determining adsorption energy, screening for optimal catalysts with volcano plots, and calculating reaction energies. Although Density Functional Theory (DFT) is effective in calculating relative energies through systematic error cancellation, the accuracy of Graph Neural Networks (GNNs) in this regard remains uncertain. To address this, we analyzed ∼483 × 106 pairs of energy differences predicted by DFT and GNNs using the Open Catalyst 2020-Dense dataset. Our analysis revealed that GNNs exhibit a correlated error that can be reduced through subtraction, challenging the assumption of independent errors in GNN predictions and leading to more precise energy difference predictions. To assess the magnitude of error cancellation in chemically similar pairs, we introduced a new metric, the subgroup error cancellation ratio. Our findings suggest that state-of-the-art GNN models can achieve error reduction of up to 77% in these subgroups, which is comparable to the error cancellation observed with DFT. This significant error cancellation allows GNNs to achieve higher accuracy than individual energy predictions and distinguish subtle energy differences. We propose the marginal correct sign ratio as a metric to evaluate this performance. Additionally, our results show that the similarity in local embeddings is related to the magnitude of error cancellation, indicating the need for a proper training method that can augment the embedding similarity for chemically similar adsorbate–catalyst systems.
Transcorrelated coupled cluster methods. II. Molecular systems
Authors: Schraivogel Thomas , Christlmaier Evelin Martine Corvid , López Ríos Pablo , Alavi Ali , Kats Daniel
Published: June 2023

We demonstrate the accuracy of ground-state energies of the transcorrelated Hamiltonian, employing sophisticated Jastrow factors obtained from variational Monte Carlo, together with the coupled cluster and distinguishable cluster methods at the level of singles and doubles excitations. Our results show that already with the cc-pVTZ basis, the transcorrelated distinguishable cluster method gets close to the complete basis limit and near full configuration interaction quality values for relative energies of over thirty atoms and molecules. To gauge the performance in different correlation regimes, we also investigate the breaking of the nitrogen molecule with transcorrelated coupled cluster methods. Numerical evidence is presented to further justify an efficient way to incorporate the major effects coming from the three-body integrals without explicitly introducing them into the amplitude equations.
Observation of the two-photon transition enhanced first hyperpolarizability spectra in cinnamaldehyde derivatives: A femtosecond regime study
Authors: dos Santos Carlos H. D. , Zucolotto Cocca Leandro H. , Pelosi André Gasparotto , Batista Vasco F. , Pinto Diana C. G. A. , Faustino M. Amparo F. , Vivas Marcelo G. , de Paula Siqueira Jonathas , Mendonça Cleber R. , De Boni Leonardo
Published: June 2023

The application of nonlinear optical effects in optoelectronic devices is still scarce because the irradiance threshold necessary to induce a specific effect is very high. In this context, knowing the frequency-resolved first order molecular hyperpolarizability (β) is essential to identifying regions where this response is intense enough to allow for applications in commercial devices. Thus, herein, we have determined the β spectral dependence of five new push–pull cinnamylidene acetophenone derivatives using femtosecond laser-induced Hyper-Rayleigh Scattering (HRS). A considerable increase in β values was observed in molecules. We found remarkable β values in regions near the two-photon resonance, which are mediated by electron withdrawing and donating groups. This effect was mapped using wavelength-tunable femtosecond Z-scan technique. Furthermore, it was modeled in light of the sum-over-states approach for the second- and third-order nonlinearities. Finally, our outcomes suggest a strategy to obtain large β values mediated by the 2PA transition.
Revisiting thermal transport in single-layer graphene: On the applicability of thermal snapshot interatomic force constant extraction methodology for layered materials
Authors: Alam Shadab , Gokhale Amey G. , Jain Ankit
Published: June 2023

The thermal conductivities of single-/bi-layer graphene and bulk-graphite are obtained using the Boltzmann transport equation (BTE) framework by accounting for three-phonon and four-phonon scatterings. For single-layer graphene, the thermal conductivity and interatomic force constants obtained using temperature-independent finite-difference, and temperature-dependent molecular dynamics-based approaches agree with each other. The use of the thermal snapshot approach to get temperature-dependent force constants results in a non-physical description of interatomic distances for single-layer graphene. The predicted thermal conductivity at room temperature using finite-difference based force constants is 800 W/m K, which is a severe under-prediction of experimentally measured values. For bi-layer graphene and bulk graphite, the thermal snapshot methodology is applicable and thermal conductivity changes by 25% and 5% with temperature-dependent force constants. The effect of four-phonon scattering is less than 10% on the predicted thermal conductivity of bi-layer graphene and graphite, and the obtained thermal conductivities using thermal snapshot methodology are in agreement with the literature. The limitation in the prediction of thermal conductivity of single-layer graphene via the BTE approach stems from non-accountability of temperature-dependence in finite-difference based force constants and non-physical description of interatomic bonds in thermal snapshot based force constants extraction for planar 2-atoms unitcell of single layer graphene.
Design optimization and flow analysis of discrete tip injection in a transonic compressor based on nonlinear harmonic method and endwall blockage attenuation
Authors: Benini Ernesto
Published: June 2023

Discrete tip injection (DTI) shows great promise for improving the operating stability of transonic axial flow compressor (AFC) rotors. However, the design optimization of DTI remains a challenging task because of both the reliance on computationally expensive unsteady simulations to calculate its effects and the lack of a flow physics-based index for assessing operating stability. The present study introduces a nonlinear harmonic method for the rapid simulation of the dominant unsteady effects caused by a DTI device, and it proposes the unsteady shroud endwall blockage attenuation as an operating stability optimization index for DTI design based on analyzing the stall flow mechanism in transonic AFCs. On this basis, an efficient optimization method for DTI design is proposed in combination with an adaptive kriging-based optimization technique. This design optimization method is validated by the Coandă injector design for the transonic rotor National Aeronautics and Space Administration Rotor 37, with improved operating range and reduced injection mass flow pursued simultaneously by a comprehensive objective function. The optimal DTI design significantly reduces the stalling flow coefficient of the compressor by 4.46% at a small injection mass flow (0.72% of the compressor stalling mass flow), with a slight increase in the aerodynamic performance of the compressor. Detailed unsteady flow-field analysis shows that the main reason for the improved operating stability of the transonic AFC is a significant attenuation and delayed recovery of shroud endwall blockage, and the underlying flow mechanism is elucidated well.
Optimized basis sets for DMRG calculations of quantum chains of rotating water molecules
Authors: Serwatka Tobias , Roy Pierre-Nicholas
Published: June 2023

In this contribution, we employ a density matrix-based optimization procedure to obtain customized basis functions to describe chains of rotating water molecules in interaction regimes associated with different intermolecular distances. This procedure is shown to yield a very compact basis with a clear truncation criterion based on the population of the single particle basis functions. For the water trimer, we discuss the convergence behavior of several properties and show it to be superior when compared to an energy-based truncated basis. It is demonstrated that the optimized basis reduces the necessary number of basis functions by at least an order of magnitude. Finally, the optimization procedure is employed to study larger chains of up to ten water molecules. The formation of hydrogen bonds as well as its impact on the net polarization of the chain is discussed.
Red light-induced inhibition of maize (Zea mays) mesocotyl elongation: evaluation of apoplastic metabolites
Authors: Sharova Elena , Bilova Tatiana , Tsvetkova Elena , Smolikova Galina , Frolov Andrej , Medvedev Sergei
Published: June 2023

Light is a crucial factor affecting plant growth and development. Besides providing the energy for photosynthesis, light serves as a sensory cue to control the adaptation of plants to environmental changes. We used the etiolated maize (Zea mays) seedlings as a model system to study the red light-regulated growth. Exposure of the maize seedlings to red light resulted in growth inhibition of mesocotyls. We demonstrate for the first time (to the best our knowledge) that red light affected the patterns of apoplastic fluid (AF) metabolites extracted from the mesocotyl segments. By means of the untargeted gas chromatography-mass spectrometry (GC-MS)-based metabolomics approach, we identified 44 metabolites in the AF of maize mesocotyls and characterised the dynamics of their relative tissue abundances. The characteristic metabolite patterns of mesocotyls dominated with mono- and disaccharides, organic acids, amino acids, and other nitrogen-containing compounds. Upon red light irradiation, the contents of β-alanine, putrescine and trans-aconitate significantly increased (P-value < 0.05). In contrast, there was a significant decrease in the total ascorbate content in the AF of maize mesocotyls. The regulatory role of apoplastic metabolites in the red light-induced inhibition of maize mesocotyl elongation is discussed.
Gay, bisexual, and queer men’s confidence in the Undetectable equals Untransmittable HIV prevention message: longitudinal qualitative analysis of the sexual decision-making of pre-exposure prophylaxis users over time
Authors: Grace Daniel , Daroya Emerich , Gaspar Mark , Wells Alex , Hull Mark , Lachowsky Nathan , Tan Darrell H. S.
Published: June 2023

Background Our objective was to understand what gay, bisexual, and queer men (GBQM) who had experience using pre-exposure prophylaxis (PrEP) thought about the ‘Undetectable equals Untransmittable’ (U=U) message and how it informed their sexual decision-making over time. Methods We conducted annual longitudinal qualitative interviews (2020–22) with 17 current or former PrEP users as part of a mixed-methods implementation science study examining barriers and facilitators to PrEP awareness, access, and adherence. Over 3 years, 47 interviews were conducted with GBQM in Ontario, Canada. Interviews were transcribed verbatim and coded in NVivo following reflexive thematic analysis. Results Participants’ sexual health decision-making was informed by their confidence in biomedical HIV prevention and the person taking medication (i.e. themselves using PrEP versus a real/imagined person living with HIV (PLHIV)). Longitudinal narratives of U=U clustered around four overarching themes: (1) U=U confidence (i.e. increasing trust in U=U irrespective of their PrEP use); (2) PrEP confidence (i.e. accounts of self-reliance and PrEP as sufficient HIV protection); (3) combination confidence (i.e. trusting U=U and PrEP as a package); and (4) partner confidence (i.e. potential ‘distrust’ of U=U due to uncertainties about partners’ medication adherence). Overall, men described increased sex with PLHIV over time, including some participants who, during earlier interviews, said they would ‘never be comfortable’ with serodifferent sexual partners. Conclusions GBQM’s use of PrEP shaped how they thought about U=U and sex with PLHIV. Although many GBQM embraced treatment as prevention/U=U as significant to their sexual lives, longitudinal analysis revealed its varied and uneven adoption across participants and time.
Sensing prior constraints in deep neural networks for solving exploration geophysical problems
Authors: Wu Xinming , Ma Jianwei , Si Xu , Bi Zhengfa , Yang Jiarun , Gao Hui , Xie Dongzi , Guo Zhixiang , Zhang Jie
Published: June 2023

One of the key objectives in geophysics is to characterize the subsurface through the process of analyzing and interpreting geophysical field data that are typically acquired at the surface. Data-driven deep learning methods have enormous potential for accelerating and simplifying the process but also face many challenges, including poor generalizability, weak interpretability, and physical inconsistency. We present three strategies for imposing domain knowledge constraints on deep neural networks (DNNs) to help address these challenges. The first strategy is to integrate constraints into data by generating synthetic training datasets through geological and geophysical forward modeling and properly encoding prior knowledge as part of the input fed into the DNNs. The second strategy is to design nontrainable custom layers of physical operators and preconditioners in the DNN architecture to modify or shape feature maps calculated within the network to make them consistent with the prior knowledge. The final strategy is to implement prior geological information and geophysical laws as regularization terms in loss functions for training the DNNs. We discuss the implementation of these strategies in detail and demonstrate their effectiveness by applying them to geophysical data processing, imaging, interpretation, and subsurface model building.
Design and analysis of actively tunable absorbers combined with diodes and magnetic material
Authors: Lin Weijiong , Leng Shaoyong , Zhang Junming , Wang Tao
Published: June 2023

A periodic structure absorber combined with diodes and magnetic material is proposed in this paper. By changing the power supply voltage, the absorbing performance of the absorber can be changed to adapt to different electromagnetic environments. The influence of the diode resistance variation for the absorption property of the absorber is explored by the symmetry model and the equivalent circuit model, and the role of the diode is cleared in realizing the tunability of the absorber. The design of the branch structure circuit creates two absorbing peaks in the absorber, and due to the adding of the magnetic material, the structure proposed in this paper has the advantages of wider adjustable frequency and lower frequency absorption peaks. Experiments show that the absorption peak of the absorber changes from 4.3 GHz to 8.8 GHz when the bias voltage is changed from 0 to 9 V and the reflectivity envelope covers a broadband of 4–4.6 GHz and 6–9.3 GHz below −10 dB.
Unsteady ternary hybrid-nanofluid flow over an expanding/shrinking cylinder with multiple slips: a Yamada–Ota model implementation
Authors: Shaheen Naila , Ramzan Muhammad , Kadry Seifedine , Abbas Mohamed , Saleel C Ahamed
Published: June 2023

The primary objective of this investigation is to examine the thermal state of an unsteady ternary hybrid-nanofluid flow over an expanding/shrinking cylinder. The influence of radiation along with a non-uniform thermal source/sink is taken into account to expedite heat distribution. Multiple slips are considered at the cylinder interface. The mathematical model is simplified by incorporating appropriate transformations. A numerical solution is obtained using the bvp4c algorithm. The flow characteristics and behavior of the trihybrid nanoliquid exhibit significant changes when the cylinder expands or contracts. The effects of various emerging parameters are analyzed using graphical representations. The velocity field shows an opposite trend when the unsteadiness and mass transfer parameters are increased. The thermal field improves with higher values of the non-uniform source/sink parameter but deteriorates with an increase in the thermal slip parameter. The drag force increases with higher values of the unsteadiness parameter, while it decreases with amplified values of the mass suction and velocity slip parameters. A strong correlation is observed with previous studies which validates and strengthens the credibility of the present analysis.
Aptamer-modified atomically precise gold nanoclusters as targeted nanozymes to scavenge reactive oxygen species in white adipocytes
Authors: Ding Jialuo , Du Yanhui , Hu Xinying , Zhao Mengyuan , Li Yeying , Li Le , Su Yu , Lin Zhenkun
Published: June 2023

Oxidative stress caused by excessive reactive oxygen species (ROS) leads to the dysfunction of white adipocytes and white fat, and also promotes triglyceride storage by inhibiting the respiration of adipocytes directly. Nanozymes, as a new generation of artificial enzymes, have exhibited attractive potential in scavenging ROS and treatment of ROS-related diseases. Herein, aptamer-modified atomically precise gold Au25 nanoclusters (Apt-Au25 NCs), are employed as targeted nanozymes to scavenge ROS in white adipocytes. Our results show that Apt-Au25 NCs have high targeting capability toward white adipocytes with low cytotoxicity. Furthermore, Apt-Au25 NCs show high superoxide dismutase (SOD)-like and catalase (CAT)-like activity in a concentration-dependent manner, and also good thermal and pH stability compared with natural SOD and CAT. Finally, the efficiency of ROS scavenging by Apt-Au25 NCs in white adipocytes is evaluated. This work demonstrates that Apt-Au25 NCs, as targeted nanozymes, are efficient in scavenging ROS in white adipocytes, exhibiting promising potential for the treatment of obesity and related diseases.
Surface deformation studies of TiO2 thin films by double exposure laser holographic interferometry
Authors: Arul A R , Ramalingam H B , Balamurugan R
Published: June 2023

Double exposure laser holographic interferometry is implemented to investigate the surface deformation of an stainless steel (SS) 304 substrate during the deposition of titanium dioxide (TiO2) thin films on it. The TiO2 thin film is synthesized by the potentiostatic mode in the electrodeposition process. The in-situ analysis of the stress on the substrate and the thickness of the deposition is evaluated by non-destructive holographic interferometry. The holography interference fringes are computed and show that the TiO2 film thickness increases with an escalation in deposition time, but the stress on the substrate decreases.
Triple-channel reflective splitter in terahertz band by second-order Littrow illumination
Authors: Liu Liqun , Wang Bo , Xiong Zhichao
Published: June 2023

In this paper, a triple-channel reflective beam splitter in terahertz band with connecting layer under second Bragg incidence is presented. A rigorous coupled-wave analysis is applied to optimize the profile of the grating at 2.52 THz. The optimal parameters of the grating are also verified by using the finite element method to ensure the accuracy of the data. The impact of the incident angle, incident wavelength, duty cycle, and period is analyzed in detail. For the optimized grating working in terahertz band, results for diffraction efficiencies approaching over 30% for transverse-electric polarization in three propagating orders and for transverse-magnetic polarization in the -1st order and -2nd order are derived. Obtaining stable and superior performances, the proposed three-port beam splitter working in the terahertz band is novel and could be an inspiration to design new gratings.
Erratum: Virtual double-well potential for an underdamped oscillator created by a feedback loop (2022 J. Stat. Mech.
053209)
Authors: Dago Salambô , Pereda Jorge , Ciliberto Sergio , Bellon Ludovic
Published: June 2023

In this note, we correct the expression of the switching rate

of the potential barrier

for a system at temperature T expressed in equation (8) and derived in appendix B. We also update below all the equations using the switching rate expression. The error is nevertheless small enough to not change any of the other results or conclusions of the paper. The error came from the assumption that the total energy in the double well potential E was simply distributed according to the Boltzmann probability distribution

P
(
E
)
=

1

k
B

T

exp
−
E
/
(

k
B

T
)

, which would be valid only in an harmonic potential. Indeed, in the double well potential, the motion period

depends on the system energy. Therefore the probability distribution of the energy P(E) is obtained by integrating the Boltzmann canonical distribution on the time range

(time range required to explore the full phase space). Contrary to the harmonic case where

is constant, here the energy dependence modifies the expression of P(E).
Comparative Analysis of Marine Atmospheric Boundary Layer Height Changes in the East China Sea Based on FNL and ERA5 Data
Authors: Chang Shujie , Zhang Yisan , Li Yongchi
Published: June 2023

This study compiled the NCEP FNL and ERA5 data from 2010 to 2019 to study the characteristics of the height changes of the marine atmospheric boundary layer (MABL) in the East China Sea and selected coastal (region A), offshore (region B), and Kuroshio areas (region C) for comparative analysis. The results show that, in general, the MABL heights of both datasets show a decreasing trend year by year, and the FNL decreasing trend is more significant. The two datasets show the largest difference in the eastern regions, while they are more consistent in the Taiwan Strait, suggesting substantial regional variations. The FNL decreasing trend is more significant than the ERA5 decreasing trend in regions A, B and C from 2014 to 2017. The root mean square (RMS) of the difference between FNL and ERA5 MABL is the largest in winter, followed by summer, showing significant seasonal variations. Regional MABL variations in the ERA5 dataset were more pronounced in summer and the areas with greater regional variations coincided with the areas with mean absolute differences and the RMS large value area of the MABL variation. Both datasets show region A had the largest differences in fall while regions B and C had the largest differences in winter. In terms of daily variation, both MABL reached their highest at 14:00, with the largest differences at 14:00 in regions A and C and at 20:00 and 02:00 in region B. Region A had the largest daily variations as reflected by its largest mean absolute difference and RMS of the 14:00 MABL differences. The effect of seasonal and daily variations in different regions must be considered to study the variation of MABL height in the East China Sea.
The Boundary Layer Characteristics and Development Mechanism of a Warm Advective Fog Event over the Yellow Sea
Authors: Liu Shuo , Tian Li , Lu Zhongyan , Sai Han , Liu Chenghan , Li Ping
Published: June 2023

A large-scale persistent fog event occurred over the Yellow Sea of China from April 27 to May 4, 2015. In this study, we used satellite remote sensing data, ground meteorological observed data, global sounding data, and reanalysis data from the National Centers for Environmental Prediction (NCEP) and sea surface temperature (SST) data from the National Oceanic and Atmospheric Administration (NOAA) to analyze the evolutionary characteristics, the boundary-layer marine meteorological characteristics, and the development mechanism of the sea fog event. The results show that the sea fog event was a warm advective fog process. The Yellow Sea was at the rear of the warm high and the front of the continental low (circulation situation with high in the east and low in the west). The southerly and southeasterly winds transported warm and moist air from the Northwest Pacific northward to the Yellow Sea which served as the water vapor source. A thermal turbulence interface was formed during the sea fog development. The weak vertical wind shear below the interface was conducive to the maintenance and development of sea fog in the area of the temperature inversion in the boundary layer and the formation of a certain thickness of sea fog. The sea fog occurred in the area with water vapor convergence, where the 2-m dew point was slightly higher than the SST. The area with a relative humidity greater than 90% and an air–sea temperature difference from 0 to 2 °C overlapped with the sea fog area, and these two values indicate the extent of the sea fog.
Comparative analysis of two impact systems in a snowstorm in Dalian
Authors: Sai Han , Li Yan , Liu Shuo , Geng Dan
Published: June 2023

In this study, the two influence systems in a snowstorm that occurred in January 2021 are analyzed using conventional observation, intensive snowfall observation data and NCEP-FNL 0.25°×0.25° analysis data. The results show that, first, the westerly trough combined with the surface convergence line and the sub cold front produces strong snowfall in the southern part of the Liaodong Peninsula, then the strong cold air moves southward into the cold flow snowfall. When the westerly trough system has a large water vapor flux, deep wet layer and strong ascending motion, the surface is accompanied by the obvious warm tongue in southwest Dalian and cold pad in the inland, and there is obvious frontogenesis process, with heavy snowfall. The intensity of cold advection is closely related to the amount of snowfall: the stronger the cold advections, the greater the snowfall will be. The combination of mid-upper-level divergence with negative vorticity and convergence with positive vorticity near the ground is also an advantage for heavy snowfall. Cold flow snowfall exhibits strong local characteristics. Compared with the westerly trough system, the cold flow snowfall has a smaller influence area and intensity. The combination of strong ascending motion and wet area is also one of the focuses of cold flow snowfall forecast in Dalian.
Scaled model testing for the helical strakes in reducing the vortex-induced vibrations
Authors: Sun Jiayao , Mo Shiqi , Ye Renchuan , Liu Hu
Published: June 2023

The accuracy of the prediction of the suppression efficiency of the triplex helical strakes for vortex-induced vibrations (VIV) is important in the offshore industry for the risers. Towing tank tests of the 1:1 section model have been used in the study of one degree of freedom; however, this method requires a long time for both the preparation and the testing. In this study, a scaled model testing method based on the flume and the oscillating frame is proposed, which measured the oscillating amplitude and the forces for both the bare pipe and the triplex helical strakes. The scaled tests were carried out in the TU Delft, with the range of Reynolds number between 6000 and 20000. The results were compared with the real model test applied in the towing tank to evaluate the accuracy. The measured strake efficiency of the scale model test agrees with the full-scale model test, providing support for the scaled model test in reducing the vortex-induced vibrations.
Experimental study of Stokes drift in combined wave-current flows using Particle Image Velocimetry
Authors: Zhang X , Zheng J H , Zhang C
Published: June 2023

In the present study, Eulerian velocities were obtained using the PIV system to investigate the problem of Stokes drift in combined wave-current flows. Time-averaged mean Eulerian velocity profiles were presented after the flow has achieved its equilibrium status. Waves with various wave periods and amplitudes were generated and propagated with the turbulent current possessing a Reynolds number of 32000. Results of the time-averaged mean velocity profiles suggest the absence of a return flow in an open flume. The discrepancies of the depth-averaged mean velocity with and without waves superimposed were found to be in good agreements with the return flow speeds as predicted by Kim (1984). This further confirmed the applicability of their solution for calculating the return flow under the condition of waves propagating with currents.
Inversion of Full-depth Temperature Profiles Based on Surface Temperature and AUV Measured Data
Authors: Xian Yan , Qianqian Li , Qian Tong , Ziwen Wang , Shoulian Cao , Zhichuan Ma
Published: June 2023

The sound speed profile has an important impact on sound propagation and underwater acoustic detection, and the water temperature has the most significant impact on the sound speed, so it is critical to obtain high-precision full-depth temperature profiles. With the rapid development of marine mobile platforms, it is possible to obtain depth-fixed temperature data using surface velocimeter or autonomous underwater vehicles (AUVs). This paper uses the measured thermistor chain data to carry out numerical simulation, and discusses the feasibility of reconstructed full-depth temperature profiles using measured temperature of few discrete depths. The back propagation (BP) neural network is used to generate the nonlinear mapping relationship between the temperature in a few discrete depths and the first two empirical orthogonal function (EOF) coefficients. The experimental results show that the temperature at two specially selected depths can reflect the full-depth temperature profiles to a certain extent. However, the information about the water temperature at different depths is diverse and the thermocline contains the most information. As the depth-fixed data measured by the AUV increases, the inversion accuracy of the full-depth temperature profiles increases accordingly. Results shows that, even in ocean regions that have solitary internal waves, when the depth of the depth-fixed data is selected the same as the depth of the surface layer and the two extreme points of the second EOF, the root mean square error (RMSE) of almost all reconstructed temperature profiles in the test set is less than 0.2°C, and the mean RMSE is about 0.12°C.
Correction of WindSat sea surface wind speed under rain
Authors: Jiang Zhuhui , Kong Xiaojuan , Ai Weihua , Du Xiaoyong , Ma Ming , Chen Jian , Chang Haotian , Jiang Chen , Zhang Wei
Published: June 2023

To improve the accuracy of sea surface wind speed under rain based on data obtained from the U.S. spaceborne fully polarimetric microwave radiometer (WindSat), a wind speed correction model based on a statistical algorithm is constructed. First, the coupled samples from 2003 to 2014 are considered as the training sample set, and the coupled samples from 2015 to 2020 are used as the test sample set. Then, the WindSat sea surface wind speed under rain correction model is constructed. Results show that the WindSat wind speed data is overestimated severely. The higher the wind speed, the larger the wind speed is overestimated. The experimental results reveal that the WindSat wind speed standard deviation of the test samples is 2.6 m/s. However, the wind speed standard deviation decreases to 2.2 m/s after correction.
Automatic Detection of Eddies Based on Remote Sensing SAR Images
Authors: Wang Yangjun , Bai Chenzu , Ma Ming , Zhang Shuo , Liu Hengchang
Published: June 2023

A series of problems such as climate change, population explosion and energy crisis make people have to focus on the development of new energy. The 21st Century Maritime Silk Road region, with its large population and well-developed industry, is well suited for the development of new energy, especially offshore wind energy resources. Aiming at the regionalization problem of offshore wind power stations in this region, this paper uses the analysis data of ERA5, GSHHS data, combined with authoritative geography humanities data, combined with subjective and objective comprehensive weighting method, and establishes a comprehensive risk assessment system which is different from previous ones. The results show that wind energy resources, natural environment and geography humanities factors have a certain impact on the location of offshore wind power stations in the 21st century Maritime Silk Road region. Therefore, it is meaningful and necessary to add these indicators into the location index system of offshore wind power stations in the 21st Century Maritime Silk Road region.
Sea Clutter Measurement Test and Amplitude Characteristics Analysis in the South China Sea Nearshore Area
Authors: Zhao X. , Han J. , Zhang X. , Zhang J. , Li P.
Published: June 2023

To address the problem of sea clutter amplitude distribution characteristics varying with bandwidth, this paper obtains the raw data of clutter under different polarization methods of HH and VV in X and Ka bands based on the sea clutter measurement experiment carried out in June 2022 in the near-shore waters of South China Sea. For the data in X-band HH polarization mode, the goodness-of-fit test was conducted based on the classical models of Rayleigh, Weibull, log-normal and K distribution for the amplitude distribution characteristics of the sea clutter, and the variation of the estimated parameters of the distribution model with the bandwidth was analyzed. The test data show that: 1, with the increase of bandwidth sea clutter amplitude decreases; 2, with the increase of bandwidth Weibull distribution model parameters are decreasing trend, k distribution parameters are increasing trend; 3, the test conditions, the offshore sea clutter amplitude distribution is the optimal K distribution. The conclusions of this paper can provide a comparison and reference for the subsequent study on the characteristics of sea clutter distribution.
Location of the 21st Century Maritime Silk Road Marine Wind Energy Site
Authors: Xu Jing , Zhang Ren , Wang Yangjun , Yan Hengqian , Liu Quanhong , Guo Yutong , Ren Yongcun
Published: June 2023

A series of problems such as climate change, population explosion and energy crisis make people have to focus on the development of new energy. The 21st Century Maritime Silk Road region, with its large population and well-developed industry, is well suited for the development of new energy, especially offshore wind energy resources. Aiming at the regionalization problem of offshore wind power stations in this region, this paper uses the analysis data of authoritative geography humanities data and establishes a comprehensive risk assessment system. The results show that wind energy resources, natural environment and geography humanities factors have a certain influence on the location of offshore wind power stations in the region. Also, they shows that different indicators have different results. Therefore, it is meaningful and necessary to add these indicators into the location indicator system of offshore wind power stations in the region.
Ocean data compression based on block SVD
Authors: Wang Yishuo , Zhou Muping , Zhou Feng
Published: June 2023

Fast development of ocean observations and numerical modeling increases the need for data transmission, storage and extraction. This paper presented a new data compression method based on Singular Value Decomposition (SVD) with data matrix divided into different sub-matrices with consideration of odevity and remnant. An automatic matrix-dividing method is applied to divide smartly the data matrix into sub-matrices. These sub-matrices are then compressed based on an improved SVD, which enhances the compression performance by utilizing the orthogonal property of vectors generated by SVD. A dynamic optimization method which is capable of determining the proper scale of retained data under the accuracy requirement of ocean data is also established. Two indices are derived mathematically to search the best block pattern quickly. The performance and reliability of the block-based SVD compression is verified with the successful compression and recovery of the Hybrid Coordinate Ocean Model data.
An Ensemble Kalman Filter Data Assimilation Method for the Sea Surface Temperature in the China Seas: Implementation and Simulation Experiments
Authors: Li Zhijie , Li Yun , Wang Zhaoyi , Zheng Jingjing
Published: June 2023

Data assimilation refers to a method of integrating observation data in the dynamic operation of numerical models on the basis of considering the temporal and spatial distribution of data and the error of observation field and background field. The Ensemble Kalman filter (EnKF) as a technology that has been widely used in the field of atmosphere and ocean has been applied to the ROMS (the Regional Ocean Modeling System) for predicting Sea surface temperature in Yellow, and East China Seas. In order to explore the applicability and effectiveness of the EnKF method for improving the accuracy of marine numerical model, the Sea surface temperature (SST) gained from buoy were used to conduct data assimilation process with EnKF method. Twin experiments have been performed to analysis the sensitivity of this system to the ensemble size and errors in model simulation and observations and a real data assimilation scheme has been conducted to hindcast the SST at the Yellow, and East China Seas during the July of year 2014. The updated results after data assimilation indicate that the model simulation fits observation better when the forecast was updated by observations. The result show that EnKF can effectively reduce the simulation error of complex numerical marine models.
Numerical Study on the Genesis of Incipient Vortex of a Tropical Storm over the South China Sea. Part II Sensitivity of Sea Surface Sensible Heating
Authors: Hao S , Liu X Y , Chen L , Liu K W
Published: June 2023

The experiments are conducted to determine the impact of the anomalous surface sensible heating (SH) from the South China Sea (SCS) on the incipient vortex of the storm Mindulle (2010) formation by using the Weather Research and Forecasting (WRF) model, including the control-run with and the sensitivity-run without such heating. Significant impact is seen, with the incipient vortex failing to generate without the related SH. Based on the atmospheric thermal adaption theory, the outputs reveal that the genesis of the incipient vortex can be divided into the formation stage and the strengthen stage. At the formation stage, the surface SH favoured the enhancement of the surface convergence. Thus strong westerlies and southerlies along with the topography forcing constrain updrafts over the Luzon Island. The non-uniform condensation latent heating (LH) released by the vertical motion creates the cyclonic vorticity in the lower atmosphere, which was conducive to the incipient vortex formation. At the strengthen stage, the more intense LH due to the enhanced ascending motions mainly contributed to cyclonic vorticity generation. Therefore, the incipient vortex continuously strengthened and attained to the intensity of tropical storm. The simulation results illustrate that the development of the Mindulle (2010) is a “bottom-up” process.
Improvements of ocean fronts forecasting in the South China Sea by using ensemble optimal interpolation assimilation
Authors: Ren S , Zu Z , Zhu X , Wang Y , Zhang Y
Published: June 2023

Based on the operational ocean forecasting system in the South China Sea (SCS) runned by National Marine Environmental Forecasting Center (NMEFC), current Ensemble Optimal Assimilation (EnOI) system are updated by developing the dynamic coordination of multi-source data assimilation system, and has carried on the systematic evaluation. The diagnostic analysis of ocean fronts in the SCS is carried out using the daily average hindcast results in 2018, and the improvement effect of data assimilation on ocean mesoscale processes was evaluated. The statistical analysis results show that the occurrence frequency and diagnostic parameters of the ocean front after assimilation are closer to the observation. The comparison of the scores of the ocean front prediction skills before and after assimilation shows that the assimilated model has higher front prediction skills.
The Long-term variability of Global Typical Oceanic Fronts
Authors: Liao Haolin , Zhang Yongchui
Published: June 2023

Using high-resolution NOAA Optimum Interpolation sea surface temperature (OISST) data, the temporal and spatial characteristics of typical oceanic fronts in the past 39 years, including Oyashio front, Gulf Stream front, Peru current front and southern Indian Ocean polar front, are analyzed. The results show that the intensities of the four typical fronts have all strengthened, among which the Peru current is the most significant and the South Indian Ocean polar front is the weakest. The movement of the fronts are quite different: the Oyashio front has a significant poleward movement, and the Gulf Stream front extending into the open sea part has a marginal poleward movement; while the south Indian Ocean polar front and Peru current front have no obvious movements.
Long-term thermohaline trends in the Sulawesi Sea based on a high-resolution reanalysis data
Authors: Li Aojie , Zhang Yongchui
Published: June 2023

Based on the global ocean reanalysis data of COPERNICUS MARINE ENVIRONMENT MONITORING SERVICE (CMEMS) from 1993 to 2019, the long-term thermohaline trends in the Sulawesi Sea are analyzed. The results show that the temperature of the upper middle layer of the Sulawesi Sea has a long-term increasing trend, and the fastest warming is located at 130m, which is 0.05°C/yr, implying a total of 1.35°C in the 27 years. For salinity, there is a whole negative trend, except for the surface layer. Further study shows that the temperature and salinity interannual variations show positive and negative correlation with Niño index, respectively.