bluuebunny/crossref_metadata_2025 huggingface dataset:
Prediction and design of protease enzyme specificity using a structure-aware graph convolutional network
Authors: Lu Changpeng , Lubin Joseph H. , Sarma Vidur V. , Stentz Samuel Z. , Wang Guanyang , Wang Sijian , Khare Sagar D.
Published: September 2023

Site-specific proteolysis by the enzymatic cleavage of small linear sequence motifs is a key posttranslational modification involved in physiology and disease. The ability to robustly and rapidly predict protease–substrate specificity would also enable targeted proteolytic cleavage by designed proteases. Current methods for predicting protease specificity are limited to sequence pattern recognition in experimentally derived cleavage data obtained for libraries of potential substrates and generated separately for each protease variant. We reasoned that a more semantically rich and robust model of protease specificity could be developed by incorporating the energetics of molecular interactions between protease and substrates into machine learning workflows. We present Protein Graph Convolutional Network (PGCN), which develops a physically grounded, structure-based molecular interaction graph representation that describes molecular topology and interaction energetics to predict enzyme specificity. We show that PGCN accurately predicts the specificity landscapes of several variants of two model proteases. Node and edge ablation tests identified key graph elements for specificity prediction, some of which are consistent with known biochemical constraints for protease:substrate recognition. We used a pretrained PGCN model to guide the design of protease libraries for cleaving two noncanonical substrates, and found good agreement with experimental cleavage results. Importantly, the model can accurately assess designs featuring diversity at positions not present in the training data. The described methodology should enable the structure-based prediction of specificity landscapes of a wide variety of proteases and the construction of tailor-made protease editors for site-selectively and irreversibly modifying chosen target proteins.
Calcium binding and permeation in TRPV channels: Insights from molecular dynamics simulations
Authors: Liu Chunhong , Xue Lingfeng , Song Chen
Published: September 2023

Some calcium channels selectively permeate Ca2+, despite the high concentration of monovalent ions in the surrounding environment, which is essential for many physiological processes. Without atomistic and dynamical ion permeation details, the underlying mechanism of Ca2+ selectivity has long been an intensively studied, yet controversial, topic. This study takes advantage of the homologous Ca2+-selective TRPV6 and non-selective TRPV1 and utilizes the recently solved open-state structures and a newly developed multisite calcium model to investigate the ion binding and permeation features in TRPV channels by molecular dynamics simulations. Our results revealed that the open-state TRPV6 and TRPV1 show distinct ion binding patterns in the selectivity filter, which lead to different ion permeation features. Two Ca2+ ions simultaneously bind to the selectivity filter of TRPV6 compared with only one Ca2+ in the case of TRPV1. Multiple Ca2+ binding at the selectivity filter of TRPV6 permeated in a concerted manner, which could efficiently block the permeation of Na+. Cations of various valences differentiate between the binding sites at the entrance of the selectivity filter in TRPV6. Ca2+ preferentially binds to the central site with a higher probability of permeation, repelling Na+ to a peripheral site. Therefore, we believe that ion binding competition at the selectivity filter of calcium channels, including the binding strength and number of binding sites, determines Ca2+ selectivity under physiological conditions.
Mechanisms of dihydropyridine agonists and antagonists in view of cryo-EM structures of calcium and sodium channels
Authors: Tikhonov Denis B. , Zhorov Boris S.
Published: September 2023

Opposite effects of 1,4-dihydropyridine (DHP) agonists and antagonists on the L-type calcium channels are a challenging problem. Cryo-EM structures visualized DHPs between the pore-lining helices S6III and S6IV in agreement with published mutational data. However, the channel conformations in the presence of DHP agonists and antagonists are virtually the same, and the mechanisms of the ligands’ action remain unclear. We docked the DHP agonist S-Bay k 8644 and antagonist R-Bay k 8644 in Cav1.1 channel models with or without π-bulges in helices S6III and S6IV. Cryo-EM structures of the DHP-bound Cav1.1 channel show a π-bulge in helix S6III but not in S6IV. The antagonist’s hydrophobic group fits into the hydrophobic pocket formed by residues in S6IV. The agonists’ polar NO2 group is too small to fill up the pocket. A water molecule could sterically fit into the void space, but its contacts with isoleucine in helix S6IV (motif INLF) would be unfavorable. In a model with π-bulged S6IV, this isoleucine turns away from the DHP molecule and its position is occupied by the asparagine from the same motif INLF. The asparagine provides favorable contacts for the water molecule at the agonist’s NO2 group but unfavorable contacts for the antagonist’s methoxy group. In our models, the DHP antagonist stabilizes entirely α-helical S6IV. In contrast, the DHP agonist stabilizes π-bulged helix S6IV whose C-terminal part turned and rearranged the activation-gate region. This would stabilize the open channel. Thus, agonists, but not antagonists, would promote channel opening by stabilizing π-bulged helix S6IV.
EURAMET.T-K.7 Comparison : Inter-laboratory comparison of triple point of water cells
Authors: Kalemci Murat , Uytun Ali , Hodžić Nedžadeta , Al Otaibi Oqab N , Al Faleh Ismail A , Anagnostou Miltiadis , Flaifel Mustafa
Published: September 2023

Main text

The purpose of this comparison was to compare the results of the participating laboratories at the triple point of water temperature (TPW) and assess the uncertainty on the practical realization of triple point of water temperature by the participant laboratories and also to support the Calibration and Measurement Capabilities (CMC) entries of the participating laboratories for this fixed point. This comparison was initiated as a EURAMET project with project number 1357. Initially, the participants of the comparison included the Metrology Institutes of Albania (DPM), F.Y.R Macedonia (BOM), Montenegro (MBM) and Serbia (DMDM). But at the later stages of the comparison, these countries understandably chose to leave the comparison instead of repeating the measurements due to an unexpected problem. On the other hand, participants from GULFMET organization, Emirates Metrology Institute (EMI) and National Measurement and Calibration Center at Saudi Standards, Metrology and Quality Organization of the Kingdom of Saudi Arabia (SASO NMCC) and also Jordan National Metrology Institute (JNMI) were included in the comparison after having approvals of each participating laboratory. Then the comparison was registered as Key Comparison with the name EURAMET.T-K7-4 in BIPM KCDB. Finally, two loops was combined together and five institutes performed the comparison with the single circulating TPW Cell. This report presents the results of the TPW comparison and gives detailed information about the measurements made at TUBİTAK UME and participating laboratories.

To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.

The final report has been peer-reviewed and approved for publication by the CCT, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).
(Avoided) crossings in the spectra of matrices with globally degenerate eigenvalues
Authors: Silliman S , Bhattacharya M
Published: September 2023

(Avoided) crossings are ubiquitous in physics and are connected to many physical phenomena such as hidden symmetries, the Berry phase, entanglement, Landau–Zener processes, the onset of chaos, etc. A pedagogical approach to cataloging (avoided) crossings has been proposed in the past, using matrices whose eigenvalues avoid or cross as a function of some parameter. The approach relies on the mathematical tool of the discriminant, which can be calculated from the characteristic polynomial of the matrix, and whose roots as a function of the parameter being varied yield the locations as well as degeneracies of the (avoided) crossings. In this article we consider matrices whose symmetries force two or more eigenvalues to be degenerate across the entire range of variation of the parameter of interest, thus leading to an identically vanishing discriminant. To show how this case can be handled systematically, we introduce a perturbation to the matrix and calculate the roots of the discriminant in the limit as the perturbation vanishes. We show that this approach correctly generates a nonzero ‘reduced’ discriminant that yields the locations and degeneracies of the (avoided) crossings. We illustrate our technique using the matrix Hamiltonian for benzene in Hückel theory, which has recently been discussed in the context of (avoided) crossings in its spectrum.
Partial identification of visible lines from W24+ ions in an electron-beam ion trap
Authors: Li B L , Qu F H , Fu N , Xie Y M , Liu X , Yang Y , Wei B , Zou Y , Xiao J
Published: September 2023

To better understand the structure of the open

4

f

shell, the spectroscopic data in the 420–600 nm range of the highly charged ions of W24+ obtained with an electron beam ion trap are presented. Detailed collisional-radiative (CR) modeling has been used to simulate the spectrum. The atomic structure data for the CR modeling were calculated using the relativistic many-body perturbation theory (RMBPT) and the large-scale relativistic configuration interaction (RCI) method implemented in the flexible atomic code. The two set theoretical calculation wavelengths for six observed lines are in reasonable agreement with the experimental observations, with average deviations of 0.61% for RMBPT and 1.75% for RCI. The relative intensities of the identified lines have also been investigated, revealing a strong correlation to electron density from

n
e

= 109 to 1011 cm−3.
How to benchmark triboelectric nanogenerator: a review
Authors: Chen Chaojie , Xu Guoqiang , Fu Jingjing , Zhang Bo , Guan Dong , Li Chuanyang , Zi Yunlong
Published: September 2023

Triboelectric nanogenerators (TENGs) can convert random mechanical vibrations around the environment into electricity and have huge potential in artificial intelligence, blue energy, carbon neutrality, human–machine interface, e-skin, etc. Although many efforts have been made on the working mechanism and performance enhancement in the past decade, characterizing and evaluating the performance of TENGs remains challenging due to the lack of benchmarking guidelines. Previous works based on different measurement methods and metrics as well as the lack of details result in difficulties in performance comparison. In this review, we discuss fundamental works on electrical measurement and performance evaluation of TENGs. Issues in measurement are elucidated and corresponding solutions are presented. Then, the origin and development of the figure-of-merits (FOMs) of TENGs are reviewed. The standardization not only broadens our understanding but also facilitates the commercialization and industrialization of TENGs. We believe that the correct measurement and fair evaluation can promote the performance assessment of TENGs and the continuous development of this field.
Adaptive spectrum segmentation Ramanujan decomposition and its application to gear fault diagnosis
Authors: Huang Shunqing , Yang Yu , Cheng Jian , Hu Niaoqing , Cheng Zhe
Published: September 2023

Ramanujan Fourier mode decomposition (RFMD) is a novel non-stationary signal decomposition method, which can decompose a complex signal into several components and extract the periodic characteristics of the signal. However, the mode generation method adopted by RFMD does not consider the physical meaning of the component signal, which makes over-decomposition when dealing with real-life gear signals with complex modulation characteristics, thus destroying the integrity of the signal sideband, increasing the difficulty of subsequent analysis, and even losing key fault information. The iterative envelope-segmentation algorithm combines the modulation characteristics of the local fault gear signal and divides the original signal into a limited number of dominant frequency bands containing the modulation region in the Fourier spectrum, thereby ensuring that the obtained frequency bands contain rich fault information. Based on the above algorithm, a new adaptive decomposition method is proposed in this paper, which is adaptive spectrum segmentation Ramanujan decomposition (ASSRD). ASSRD uses fault envelope harmonic noise ratio as the index to evaluate the fault information content of component signals and uses it to assist the iterative envelope-segmentation algorithm to complete the adaptive segmentation of the Fourier spectrum. Finally, based on the segmentation result, the inverse RFT reconstruction of each frequency band is performed. Thus, the signal is decomposed into a finite number of component signals containing rich fault information. In addition, through the experiment on the gear simulation signal and the measured crack fault gear signal, the ASSRD method is compared with the original RFMD method and the existing ensemble empirical mode decomposition (EMD), variational mode decomposition, empirical wavelet transform, and singular spectrum decomposition method, verifying the feasibility and superiority of ASSRD in gear fault diagnosis. Besides, a comparative experiment based on compound faults diagnosis is carried out, in which ensemble EMD, Fourier decomposition method, empirical wavelet transform, and sparse decomposition are involved. The results show that the proposed method can extract the local fault information in the gear signal more effectively, and the performance is better than the comparison method.
CACDT: an approach to cross-machine bearing fault diagnosis
Authors: Zhao Xiaoping , Xu Wenbo , Dai Zhengyi , Lin Zhichen
Published: September 2023

Mechanical fault transfer diagnosis utilizes the acquired diagnostic knowledge of machinery to address diagnostic issues in the target machinery. This approach demonstrates promising results in overcoming the limitations of incomplete fault information and scarce labeled data in the era of big data. However, when confronted with cross-machine fault diagnosis, the significant domain discrepancies pose challenges to traditional fault diagnostic methods, leading to lower accuracy and learning efficiency. To overcome these problems, this work introduces a novel cross-machine bearing fault diagnosis model called Cross-Domain Adaptive Clustering and Dynamic Threshold. The model comprises a feature extraction network and a classifier, and it achieves intra-domain and inter-domain adaptation via adversarial optimization. The feature extraction network minimizes the adversarial adaptive clustering loss, while the classifier maximizes it. Moreover, the model calculates dynamical thresholds for each class in the target domain and generates pseudo-labels for unlabeled samples. This approach increases labeled samples for each category during early training, resulting in a more robust clustering core and improving the learning efficiency of the model. Experimental results show that, in cross-machine fault diagnosis, when the number of labels in the target domain is 5 and 10, the average accuracy reaches 82% and 95.6%, respectively, which is better than the comparison method. The model effectively distinguishes minority samples in class imbalance experiments, and the dynamic thresholds enhance learning efficiency for complex datasets compared to fixed thresholds.
Temperature measurement on copper surfaces for superconducting thin film cavity applications
Authors: Bianchi Antonio , Vandoni Giovanna , Venturini Delsolaro Walter
Published: September 2023

Superconducting radio-frequency (SRF) thin film cavities on copper substrates are employed in several particle accelerators. However, these SRF cavities historically featured a progressive performance degradation with the accelerating field that is still not completely understood. The degradation of cavity performance, which limits the use of this technology in accelerators where the real-estate gradient has to be maximized, is manifested by the presence of heat losses in the superconducting film. However, measuring the temperature on the outer surface of copper substrates is challenging due to the higher thermal conductivity of copper at low temperatures compared to niobium. This study describes how temperature variations on copper surfaces can be satisfactorily measured in view of superconducting thin film cavity applications at liquid helium temperatures. Furthermore, we explore how the thermal exchange between thermometers and copper surfaces, and thermometers and helium bath must be tuned with respect to each other in order to measure accurately temperature rises in the thin film. Our findings suggest that engineering the copper surfaces can improve heat transfer into the helium bath and potentially enhance the performance of thin film SRF cavities.
Robust structured light 3D imaging with two fringe patterns using recurrent classification neural network
Authors: Yang Tao , Liu Hao , Tang Zhenzhong , Gu Feifei
Published: September 2023

Robust and accurate 3D reconstruction using a limited number of fringe patterns has posed a challenge in the field of structured light 3D imaging. Unlike traditional approaches that rely on multiple fringe patterns, using only one or two patterns makes phase recovery and unwrapping difficult. To address this issue, a recurrent classification neural network (RCNN) has been developed, transforming the phase recovery and unwrapping tasks into a unified phase classification task. First, a training dataset consisting of 1200 groups of data was collected to generate a total of 38 400 training samples, enabling the RCNN to learn the mapping between the input fringe patterns and the corresponding label maps. Then, based on the well-trained network, a label map is generated based on the input two fringe patterns using the output classification results. Finally, 3D reconstruction data could be obtained by combining the inferred label map with the vision system’s parameters. A series of comprehensive experiments have been conducted to validate the performance of the proposed method.
Orietation-controlled synthesis and Raman study of 2D SnTe
Authors: Su Yanfei , Ding Chuyun , Yao Yuyu , Fu Rao , Xue Mengfei , Liu Xiaolin , Lin Jia , Wang Feng , Zhan Xueying , Wang Zhenxing
Published: September 2023

Tin telluride (SnTe), as a narrow bandgap semiconductor material, has great potential for developing photodetectors with wide spectra and ultra-fast response. At the same time, it is also an important topological crystal insulator material, with different topological surface states on several common surfaces. Here, we introduce different Sn sources and control the growth of regular SnTe nanosheets along the (100) and (111) planes through the atmospheric pressure chemical vapor deposition method. It has been proven through various characterizations that the synthesized SnTe is a high-quality single crystal. In addition, the angular resolved Raman spectra of SnTe nanosheets grown on different crystal planes are first demonstrated. The experimental results showed that square SnTe nanosheets grown along the (100) plane exhibit in-plane anisotropy. At the same time, we use micro-nanofabrication technology to manufacture SnTe-based field effect transistors and photodetectors to explore their electrical and optoelectronic properties. It has been confirmed that transistors based on grown SnTe nanosheets exhibit p-type semiconductor characteristics and have a high response to infrared light. This work provides a new approach for the controllable synthesis of SnTe and adds new content to the research of SnTe-based infrared detectors.
Investigating damped oscillations in simple pendulum
Authors: Wadhwa Adya , Wadhwa Ajay
Published: September 2023

We describe an experimental set-up of a simple pendulum for the measurement of damping coefficient of oscillations. We have used an Arduino microcontroller with infrared sensor interface to detect the oscillating object in its path. The Arduino program records the instants of time to calculate the time-period and the total number of oscillations. The dependence of damping coefficient on the size, shape and mass of the pendulum bob as well as on the thickness of the pendulum string is investigated.
Torsion balance helps identify ferro-, dia- and paramagnetic materials
Authors: Thompson Frank
Published: September 2023

A neodymium magnet mounted on a torsion balance was placed near samples of ferro- dia- and paramagnetic material held in a plastic container. Similar experiments have used a cotton thread (with no restoring torque) and a pencil as the balance to allow students/pupils to detect the magnetization of many household commodities such as water, Blue-tac, fruit and salt. The present work uses a metallic wire as a suspension which provides a restoring torque due to the elasticity in the wire. Thus, a measurable deflection can be observed when the magnetic and torsion forces balance. For aluminium, the initial negative deflection is a manifestation of Lenz’s law.
The global energy balance of the ASDEX Upgrade tokamak determined with the revised cooling water calorimetry
Authors: Redl A , Hohmann T , Eich T , Vianello N , Bernert M , David P , den Harder N , Herrmann A , Rohde V , Weiland M ,   the ASDEX Upgrade Team,   the EUROfusion MST1 Team
Published: September 2023

An extensive analysis of the global energy balance on the ASDEX Upgrade (AUG) tokamak has been performed. For such a purpose a complete revamping of the AUG cooling water calorimetry originally described in (Richter and Vernickel 1994 Rev. Sci. Instrum.
65 5) has been done. The system, which has been largely improved, consists of 88 cooling units, which provides an almost perfect toroidal and poloidal coverage of the in-vessel components of the AUG tokamak. To measure the energy loss due to radiation, which is only partially captured by the cooling water calorimetry, a novel framework is introduced to calculate the losses utilizing bolometric data. The analysis of the global energy balance based on almost 600 discharges reveal the remarkable capability to account more than 95% of the total injected energy on average.
Identification of trapping finer-scale fluctuations in a solitary vortex in linear magnetized plasma
Authors: Arakawa Hiroyuki , Sasaki Makoto , Inagaki Shigeru , Lesur Maxime , Kosuga Yusuke , Kobayashi Tatsuya , Kin Fumiyoshi , Yamada Takuma , Nagashima Yoshihiko , Fujisawa Akihide , Itoh Kimitaka
Published: September 2023

The mutual interaction of drift wave-type modes and zonal flows causes the formation of higher-order nonlinear structures. This study focuses on the spatio-temporal behavior of these higher-order structures in a linear magnetized plasma. The structures include a solitary vortex, a long-lived circumnavigating motion localized both radially and azimuthally, and a short-lived packet of finer-scale fluctuations excited at the position of the solitary vortex. Observing the time evolution of the two-dimensional cross-sectional structures revealed that the packet of finer-scale fluctuations is trapped in the solitary vortex. The trapping times found are consistent with the theoretical evaluation.
Break-even point of the phase-flip error correcting code
Authors: Rozgonyi Áron , Széchenyi Gábor
Published: September 2023

In this theoretical study, we explore the use of quantum code-based memories to enhance the lifetime of qubits and exceed the break-even point, which is critical for the implementation of fault-tolerant quantum computing. Specifically, we investigate the quantum phase-flip repetition code as a quantum memory and theoretically demonstrate that it can preserve arbitrary quantum information longer than the lifetime of a single idle qubit in a dephasing-time-limited system, e.g. in semiconductor qubits. Our circuit-based analytical calculations show the efficiency of the phase-flip code as a quantum memory in the presence of relaxation, dephasing, and faulty quantum gates. Moreover, we identify the optimal repetition number of quantum error correction cycles required to reach the break-even point by considering the gate error probabilities of current platforms for quantum computing. Our results provide guidelines for developing quantum memories in semiconductor quantum devices.
Inflationary cross-correlations of a non-minimal spectator and their soft limits
Authors: Sai P. Jishnu , Jain Rajeev Kumar
Published: September 2023

Light spectator fields may not be dynamically relevant for the inflationary phase of the
early universe, but they can still induce interesting imprints on cosmological observables. In
this paper, we compute the cross-correlations of the inflationary perturbations, both scalar and
tensor, with the fluctuations of a non-minimally interacting spectator field using the in-in
formalism and investigate the consistency relations associated with such cross-correlations. In
particular, the scalar consistency relation is derived semi-classically by generalizing the
consistency relation obtained earlier for cosmic magnetic fields. Notably, we find that the
direct coupling between the inflaton and the spectator solely determines the local non-linearity
parameter associated with the scalar cross-correlation during slow-roll inflation, regardless of
the specific form of the Lagrangian for the spectator field. Further, we calculate the tensor
correlation with spectator fluctuations, explore the associated soft limits, and demonstrate the
violation of the conventional tensor consistency relation with a non-minimal derivative
coupling. Our analysis stresses that the violation of tensor consistency relations does not
necessarily imply the superhorizon evolution of tensor modes. Instead, such violations can arise
due to the non-minimal derivative coupling of the spectator field to gravity. Finally, we discuss
the wider implications of our results in the context of cosmological soft theorems.
Lump solution and interaction solutions to the fourth-order extended (2+1)-dimensional Boiti–Leon–Manna–Pempinelli equation
Authors: Chen Wenxia , Wang Yi , Tian Lixin
Published: September 2023

In this paper, we explore the exact solutions to the fourth-order extended (2+1)-dimensional Boiti–Leon–Manna–Pempinelli equation. Based on Hirota bilinear method, lump solution, periodic cross-kink solutions and bright-dark soliton solutions were investigated. By calculating and solving, the peak and trough of lump solution are obtained, and the maximum and minimum points of each are solved. The three-dimensional plots and density plots of periodic cross-kink solution and bright-dark soliton solution are drawn and the dynamics of solutions under different parameters are observed.
Epitaxial growth of ultrathin gallium films on Cd(0001)
Authors: Li 李 Zuo 佐 , Shi 石 Mingxia 明霞 , Yao 姚 Gang 钢 , Tao 陶 Minlong 敏龙 , Wang 王 Junzhong 俊忠
Published: September 2023

Growth and electronic properties of ultrathin Ga films on Cd(0001) are investigated by low-temperature scanning tunneling microscopy (STM) and density functional theory (DFT) calculations. It is found that Ga films exhibit the epitaxial growth with the pseudomorphic 1 × 1 lattice. The Ga islands deposited at 100 K show a ramified shape due to the suppressed edge diffusion and corner crossing. Furthermore, the majority of Ga islands reveal flat tops and a preferred height of three atomic layers, indicating the electronic growth at low temperature. Annealing to room temperature leads to not only the growth mode transition from electronic growth to conventional Stranski–Krastanov growth, but also the shape transition from ramified islands to smooth compact islands. Scanning tunneling spectroscopy (STS) measurements reveal that the Ga monolayer exhibits metallic behavior. DFT calculations indicate that all the interfacial Ga atoms occupy the energetically favorable hcp-hollow sites of the substrate. The charge density difference analysis demonstrates that the charge transfer from the Cd substrate to the Ga atoms is negligible, and there is weak interaction between Ga atoms and the Cd substrate. These results shall shed important light on fabrication of ultrathin Ga films on metal substrates with novel physical properties.
Exploring EEG characteristics of multi-level mental stress based on human–machine system
Authors: Yao Qunli , Gu Heng , Wang Shaodi , Liang Guanhao , Zhao Xiaochuan , Li Xiaoli
Published: September 2023

Objective. The understanding of cognitive states is important for the development of human–machine systems (HMSs), and one of the fundamental but challenging issues is the understanding and assessment of the operator’s mental stress state in real task scenarios. Approach. In this paper, a virtual unmanned vehicle (UAV) driving task with multi-challenge-level was created to explore the operator’s mental stress, and the human brain activity during the task was tracked in real time via electroencephalography (EEG). A mental stress analysis dataset for the virtual UAV task was then developed and used to explore the neural activation patterns associated with mental stress activity. Finally, a multiple attention-based convolutional neural network (MACN) was constructed for automatic stress assessment using the extracted stress-sensitive neural activation features. Main Results. The statistical results of EEG power spectral density (PSD) showed that frontal theta-PSD decreased with increasing task difficulty, and central beta-PSD increased with increasing task difficulty, indicating that neural patterns showed different trends under different levels of mental stress. The performance of the proposed MACN was evaluated based on the dimensional model, and results showed that average three-class classification accuracies of 89.49%/89.88% were respectively achieved for arousal/valence. Significance. The results of this paper suggest that objective assessment of mental stress in a HMS based on a virtual UAV scenario is feasible, and the proposed method provides a promising solution for cognitive computing and applications in human–machine tasks.
Experimental Study of Heavy Oil Upgrading of In-Situ Hydrogen
Authors: Pu Wanfen , Liu Renbao , Tang Xiaodong , Li Tao
Published: September 2023

It was reported that hydrogen production from heavy oil reservoirs was feasible. To study the effect of in-situ hydrogen on heavy oil upgrading, a static experiment of hydrogen upgrading heavy oil under different conditions was designed with nitrogen as the control group. The composition and molar content of the produced gas was analyzed by gas chromatography (GC), the microstructure of coke was analyzed by scanning electron microscope (SEM), and the change of carbon number of oil was analyzed by gas chromatography-mass spectrometry (GC-MS). The results showed that in-situ hydrogen made heavy oil produce more light hydrocarbons. The porous coke produced by heavy oil in a hydrogen atmosphere was favorable for combustion. In addition, under the action of hydrogen, the hydrocarbon in heavy oil will be accelerated to transform from high-carbon number alkanes to low-carbon number alkanes. And the viscosity reduction effect was remarkable, the highest viscosity reduction rate reached 99.79%.
Li+ Interstitial Flow in Composite State Electrolyte for Solid-State Lithium Batteries with High-Loading Cathode
Authors: Bi Linnan , Song Yaochen , Long Xin , Wang Sizhe , Liao Jiaxuan
Published: September 2023

Solid-state lithium metal batteries (SSLMBs) hold high energy density and are safe and reliable. However, the polymer-based solid electrolyte possesses low ionic conductivity at ambient conditions and is incompatible with the lithium anode, which seriously hinders their practical application. Solid composite electrolyte (SCE) was prepared by fixing a fast-ion conductor of Li6.4La3Zr1.4Ta0.6O12 (LLZTO) within the P (VDF-ctfe) skeleton. The “Lewis base” effect of LLZTO can be used to construct a fast ion transport layer, realize the fast coordination/decoupling of lithium ions, form a fast ion jump, and improve the density of lithium carriers. The doped SCEs hold a high ionic conductivity of 1.2×10−3 S/cm at ambient temperature and a high migration number of 0.82. In addition, SCE-3% shows intimate compatibility with the lithium anode and LiFePO4 cathode. The assembled Li//SCE-3%/Li battery can be stably tested for 1200h at 0.1 mA/cm2, and the LiFePO4//SCE-3%//Li can charge and discharge for 70 times at 0.5 C, corresponding to 70.1% capacity retention rate, showing excellent electrochemical performance. This work gives a strategy for the design philosophy of SCE with high ion conductivity in SSLMBs.
Simulation and FPGA Implementation of Transient Power Quality Disturbance Detection
Authors: Lai Xionghui
Published: September 2023

With the access to new energy in the smart grids and the massive use of nonlinear and unbalanced large loads, the problem of power quality becomes more and more serious. At present, the transient power quality disturbance problem has been paid more attention to. The research on transient power quality is relatively late, and various detection methods and technologies are not mature. It is necessary to use more efficient methods to detect and identify transient power quality to improve the safety of electricity use. This paper proposes to detect transient power quality disturbance by wavelet transform. In this paper, the original signal modelling of five kinds of power quality problems such as voltage sag and voltage swell. The 9/7 wavelet lifting coefficient is optimized in this paper and is carried out on the MATLAB software platform to improve the processing speed of the algorithm and realize parallel processing. The simulation results show that the improved lifting wavelet processing can effectively detect the transient power quality disturbance.
One–pot fabrication and capacitive performances of coral-like polyaniline formed in saturated salt solution
Authors: Yan Huafeng , Qin Zongyi
Published: September 2023

An efficient and simple template-free approach was present to construct hierarchical coral-like polyaniline (PANI) in a saturated salt solution for scalable fabricating active material with excellent performance for supercapacitor application. The structure, morphology, and capacitance properties of coral-like PANI were investigated. The coral-like PANI with a highly crystalline structure was found to be composed of nanofibers with a diameter and length of 50–80 nm and 200–500 nm, respectively. Furthermore, the prepared PANI electrode exhibited excellent capacitive performances (465.1 F g−1 at 2 A g−1) and remained 81.0 % even at 100 A g−1, and 62.2 % retained after 2000 cycles. It showed that the coral-like PANI has great potential for development in the supercapacitor field as electrode material.
Carbon Flow Analysis Method Of Distribution Network Considering High Proportion Of New Energy
Authors: Yin Yuanke , Ye Peng , Zhang Chao , Li Zezheng , Feng Yuexin , Chen Yixian
Published: September 2023

This paper proposes a tracking method for the carbon flow intensity of the distribution network under a high proportion of new energy. Firstly, a power flow tracking model is proposed based on the proportional sharing principle. Then, considering network loss, a model on the ground of the carbon emission flow theory of the power system is established for analyzing carbon emissions in a distribution system with a high ratio of green power. Moreover, the availability and accuracy of the model are verified by the IEEE33 node example.
Fuel Consumption Rate Optimization Analysis of Dual-fuel Marine Diesel Engines Based on Orthogonal Design
Authors: Yang Chenxi , Cai Zheng , Li Siqin , Wang Qiwei , Fan Jinyu , Li Pinfang , Huang Jialiang
Published: September 2023

To investigate the influence of diesel engine operating matching parameters on the comprehensive fuel consumption rate of butanol-diesel dual-fuel engines, a high-pressure combustion chamber cycle model of a 4190ZLC-2 marine medium-speed diesel engine was established using AVL-FIRE simulation software. After establishing the optimum blending ratio of butanol, the fuel system parameters were optimized using a one-time regression orthogonal experimental design method, and a mathematical model for fuel consumption rate prediction was constructed to find the combination of parameters with the lowest fuel consumption rate as the target. The study shows that inlet pressure has the greatest influence on the fuel consumption rate, followed by EGR and inlet air temperature. The lowest fuel consumption rate was achieved by combining the following parameters: (butanol blending ratio of 20%, EGR rate 0, inlet pressure 0.233 MPa, inlet temperature 325.15 K, Injection advance angle 22.6 °CA, the diameter of oil injection hole (0.26 mm); after optimization, the fuel consumption rate was reduced by 9.96% compared to the original machine.
Simulation on Methanol Reformed High-Temperature PEM Fuel Cell System and the Experimental Verification
Authors: Zhuang Peng , Zhang Ruhang , Yu Xinhai
Published: September 2023

A mathematical model of the SRM-HTPEM power generation system was developed to simulate the effects of parameters such as temperature and molar water to methanol ratio on the performance of the reformer and the power stack in the system. The SRM-HTPEM power generation system was built at a mobile communication base station, and the energy efficiency of the system was 45.5% at an output power of 2.8 kW. The correctness of the simulation results was verified by experiments. It finds that increasing the reaction temperature and decreasing the weight hourly space velocity will enhance the conversion of methanol and increase the CO content in the reforming gas. Increasing the molar water to methanol ratio of the feed can improve the methanol conversion and reduce the CO content. However, if the molar water to methanol ratio is too high, the energy efficiency of the system may reduce. Appropriately increasing the operating temperature of the stack, anode hydrogen concentration and hydrogen excess ratio will increase the performance of the fuel cell.
Turbulence influence factor estimation of gasoline-air explosion in multi-branch tubes
Authors: Zhang Peili , Xiao Jun , Duan Jimao , Xiang Shuo , Shen Ting’ao , Yang Chaoshan
Published: September 2023

To estimate the turbulence influence of the branch tubes on the rising rate of gasoline-air mixture explosion overpressure, turbulence factor α was introduced to modify the formula of the peak rise rate of explosion overpressure. Then, the experimental data of peak explosion overpressure and overpressure rise rate under the different numbers of branches were obtained. Finally, the experimental data and laminar flame velocity were put into the overpressure rise rate correction formula, and the turbulence influence factors under different branches were calculated. The results show that increasing the number of branches will improve the turbulence degree of the explosion process. When the number of branching pipes is 1, the turbulence impact factor is about 2.0 times that in the case of no branch tube, while when the number of branch tubes is more than 1, the turbulence impact factor fluctuates about 3.5 times.
Bismuthene nanosheet anchored on planar Cu foil enabled a stable lithium metal anode
Authors: Liu Ying , Liu Wanqiang
Published: September 2023

Lithium metal as an anode is high-profile in rechargeable batteries, owing to its small gravimetric density, lowest redox potential, and incomparable theoretical specific capacity. Unfortunately, severe dendrite growth and fluctuant solid electrolyte interphase severely hampered its application. Herein, a hierarchical three-dimensional Bi/Cu skeleton is prepared by replacement reaction. The porous Bi/Cu can restrain the random deposition of Li through distribute the current evenly across the Bi/Cu electrodes. Meanwhile, the lithiophilicity of Bi reduces the nucleation overpotential. In contrast to the Cu skeleton, the 3D Bi/Cu skeleton significantly enhances the electrochemical performance. Furthermore, the prepared Bi/Cu anode owns highly stable coulombic efficiency, and symmetrical cells can maintain for more than 800 h (current density is 0.5 mA cm-2).
Off-grid Operation Research Energy Router Strategy on the Base of Hierarchical Control
Authors: Yang Junkun , Zhang Xiaohong
Published: September 2023

To coordinate off-grid control of the Energy Router, the Energy Router topology is first analyzed using isolated bidirectional full-bridge DC/DC inverters for DC ports, boost converters for PV units, and three-phase voltage-based bridge inverters for AC ports. Then the system is layered, with the lower layer developing different control strategies for different ports, the upper layer layering the DC bus voltage and dividing different operating modes in combination with the energy storage SOC, and then developing strategies for each mode. Finally, simulations are built in the MATLAB platform according to the topology to verify the possibility of off-grid operation of the energy router.
Medium and Long Term Scenario Generation of Multi-Temporal Renewable Energy Based on GAN
Authors: Hu Rong , Du Fei , Liu Zhong , Zhang Xipeng , Sun Jiawei
Published: September 2023

With China’s “double carbon” target, the future power system will show A significant percentage of the energy generated comes from renewable sources, specifically wind power, which has obvious randomness, volatility and intermittency, and will have a greater impact on the safety of the power system. How to effectively characterize the randomness and volatility of its power output is a major challenge for power system dispatch. The method we suggest in this paper utilizes generative adversarial networks to produce medium- and long-term scenarios for wind power generation. This approach allows for the creation of multiple sets of wind power generation data that share the same characteristics as the historical data., Our approach takes into account the spatial correlation between wind power generation at wind farms situated in various geographic locations, fully describing the randomness and spatio-temporal correlation of wind power, and providing an important reference for power system planning and scheduling.
Cooperative Primary Frequency Regulation Strategy of Wind Storage System Based on Variable Inertia Coefficient
Authors: Ding Lijie , Huang Gechao , Ren Zhihong , Lu Dingwen
Published: September 2023

Direct-drive permanent magnet synchronous wind turbine-generator (PMSG) is connected to the grid through the rotor side and grid side converter. The rotor speed is decoupled from the grid frequency, so PMSG output power cannot respond to the change in system frequency. However, with the gradual increase of wind power penetration, the static stability of system frequency is weakened, so the new grid-connected wind farm should have the ability of active frequency support. This paper proposes a cooperative primary frequency regulation (PFR) strategy for wind storage systems based on variable inertia coefficient. PMSG provides inertia based on the distribution of rotational kinetic energy and modifies the polarity of the inertia coefficient at the frequency recovery stage to speed up the frequency recovery. Droop control is realized by energy storage and variable power tracking control (VPPT). Energy storage and VPPT respectively suppress the frequency decrease/increase and only participate in the down/up single-side PFR, which can reduce the energy storage configuration capacity. And a safety discharge coefficient considering the state of charge (SOC) is introduced to prevent over-discharge of energy storage devices when outputting energy. Finally, the PFR capability of PMSG under the proposed control strategy is verified by simulation results.
Aerodynamic analysis of TLP offshore wind turbine under wind and waves
Authors: Hu Danmei , Zeng Li , Liu Jiang
Published: September 2023

Based on the real-scale NREL 5MW wind turbine as the analysis object, combined with the TLP floating platform, using the CFD software fluent and the Volume of Fluid (VOF) multiphase flow model, this paper simulates and analyzes the aerodynamic characteristics of the TLP floating offshore wind turbine under the wind and wave conditions by applying surge motion through UDF, and carries out an in-depth analysis of its power, axial thrust change, and blade pressure distribution. The power and axial thrust will fluctuate and change more violently as the amplitude and frequency of surge movement increase corresponding to waves. Low wave height, low amplitude, and low frequency are more obvious for local disturbance of power and axial thrust. After the surge motion is applied, the blade pressure at different times changes significantly. With the increase of amplitude, the pressure difference at the same time increases at the entire blade root, blade center, and blade tip, which focus mainly on the leading edge of the blade suction surface, and is most obvious at the blade root and least obvious at the blade tip. When the surge motion is not applied, with the increase of wave height, the front edge of the blade suction will obtain a greater negative pressure, and the pressure difference of each part will increase. The research results provide a technical reference and theoretical basis for the optimization design of the aerodynamic performance.
Design and Optimization of Flywheel Energy Storage System for Rail Transit
Authors: Gao Zhaopu , Cai Wei , Guo Qingbo , Yang Yongxi , Yang Lei
Published: September 2023

At present, the urban rail transit system has problems such as energy waste in the braking process and unstable grid voltage in the start-stop state. Aiming at the problems caused by the start-stop state of rail transit, considering the energy saving and voltage stability requirements of system energy management, a flywheel energy storage system (FESS) specially used for rail transit is designed. The energy system (FESS) can feed back the braking energy stored by the flywheel to the urban rail train power system when the rail train starts to cause the voltage and frequency of the traction microgrid to change. This paper proposes a flywheel energy management system based on a permanent magnet synchronous motor (PMSM), which can realize efficient energy management through efficient control of the flywheel side motor. The flywheel side permanent magnet synchronous motor adopts an improved flywheel speed expansion energy storage control strategy based on current feedforward control to improve the fast response capability of the flywheel, ensuring the output power of the flywheel at high speed. In addition, a specific multi-threshold voltage single FESS control strategy is suggested, which improves the energy-saving and voltage-stabilizing performance of the system.