bluuebunny/crossref_metadata_2025 huggingface dataset:
Essential collective dynamics analysis reveals nonlocal interactions of alpha-synuclein38-95 monomers with fibrillar seeds
Authors: Wu Min , Wille Holger , Stepanova Maria
Published: November 2022

Alpha-synuclein (α-syn) is a cytoplasmic protein commonly found in the nervous system. In solution, α-syn adopts disordered unfolded conformations, although it can also form α-helices upon binding to lipid membranes. Under conditions that are not yet fully understood, α-syn can misfold and aggregate, giving rise to β-sheet rich amyloid fibrils, which then tend to accumulate in degenerating neurons. This leads to Parkinson’s disease (PD) and several other conditions collectively termed synucleinopathies. Development of disease-modifying treatments requires detailed understanding of structure and dynamics of α-syn’s misfolded aggregates. We have employed 1000 ns long, all-atom molecular dynamics simulations to investigate the interaction of monomeric α-syn38-95 fragments, which contain the most important amyloidogenic regions, with preformed fibrillar seeds composed of staggered, β-sheet rich α-syn chains of matching length. The simulations indicate that α-syn38-95 monomers tend to form aggregates with the fibrillar seeds, although we have not observed alignment of the monomeric chains with β-strands of the fibril. To analyze the stability of these aggregates, we have employed the essential collective dynamics method, which allows making accurate assessment of dynamical coupling across individual atoms in macromolecules and supramolecular complexes. The analysis revealed extensive dynamical coupling across initially monomeric α-syn chains and the fibrillar seeds including distal regions thereof that did not contact the monomer directly. We have discussed structural origins of these long-range interactions, their impacts for the stability of α-syn aggregates, and potential implications for the development of anti-PD treatments.
Gentle nano-electrospray ion source for reliable and efficient generation of microsolvated ions
Authors: Zviagin Andrei , Kopysov Vladimir , Boyarkin Oleg V.
Published: November 2022

We present herein the design of a nano-electrospray ion source capable of reliable generation of large quantities of microsolvated ions. The source is based on a triple molecular skimmer scheme and can be quickly tuned to generate bare ions or their ionic complexes with up to more than 100 solvent molecules retained from solution. The performance of this source is illustrated by recording the mass spectra of distributions of ionic complexes of protonated water, amino acids, and a small protein ubiquitin. Protonated water complexes with more than 110 molecules and amino acids with more than 45 water molecules could be generated. Although the commercial ion source based on the double ion funnel design with orthogonal injection, which we used in our laboratory, is more efficient in generating ions than our triple skimmer ion source, they both exhibit comparable short-term stability in generating bare ions. In return, only the new source is capable of generating microsolvated ions.
Halogen's effect on the photoelectric properties of two-dimensional organic–inorganic hybrid perovskite (MTEA)2MAPb2X7 (X = Cl, Br, I) with a Ruddlesden–Popper structure
Authors: Wu Xiao-Juan , Ding Yu-Feng , Liu Biao , Yang Jun-Liang , Cai Meng-Qiu
Published: November 2022

Recently, a two-dimensional (2D) Ruddlesden–Popper (RP) organic–inorganic hybrid perovskite material (MTEA)2MAn−1PbnI3n+1 (n = 1–6) has attracted great attention, and experiments have reported that the thicker material (MTEA)2(MA)4Pb5I16 (n = 5) perovskite material has excellent environmental stability and improved photovoltaic stability. However, considering that the thickness of the material and the substitution of halogen anions have influence on photoelectric properties of materials. In this paper, we study the photoelectric properties of 2D RP organic–inorganic hybrid perovskite (MTEA)2MAPb2X7 (X = Cl, Br, I) (n = 2) based on the density functional theory. The calculated results show that as the halogen in (MTEA)2MAPb2Cl7 varies from Cl to I, the bandgap decreases, the absorption intensity increases, and the exciton binding energies decrease, which is significantly higher than that of MAPbI3 crystal photovoltaic materials, indicating that the material (MTEA)2MAPb2X7 (X = Cl, Br, and I) (n = 2) is more suitable as candidates for luminescent devices. Our work provides opportunities and challenges for the application of 2D RP organic–inorganic hybrid perovskites in luminescent devices.
Effects of the parameters of inner air cylinder on evolution of annular SF6 cylinder accelerated by a planar shock wave
Authors: Zheng Chun , He Yong , Zhang Huanhao , Chen Zhihua
Published: November 2022

Based on the compressible Navier–Stokes equations combined with the fifth-order weighted essentially non-oscillatory scheme, this paper discusses the interaction of a planar shock wave with an annular SF6 cylinder. The influence of the position and radius of inner cylinder on the evolution of the annular cylinder is examined in detail. Numerical schlieren results clearly show the evolution of the inner and outer interfaces induced by the Richtmyer–Meshkov instability and reveal the evolution of complex shock wave structures as the incident planar shock interacts with the annular cylinder. Shock transformation from the free precursor refraction pattern to the free precursor von Neumann refraction pattern occurs when the inner cylinder position shifts forward, while the shock transformation from the twin von Neumann refraction pattern to the free precursor refraction pattern and the shock transformation from free precursor refraction pattern to the free precursor von Neumann refraction pattern occur when the radius of the inner cylinder gradually becomes larger. The generation and transportation of vorticity on the interfaces are also analyzed, revealing that changes to the inner cylinder play a significant role. The distribution and evolution of vorticity on the interfaces influence the formation of the primary vortex structure at later stages. Quantitative analysis of the circulation and enstrophy indicates that the smaller the inner radius, the larger the value of circulation and enstrophy at the later stage.
Polyimide-based ultraviolet-operated nonvolatile photomemory device
Authors: Wu Chi-Chang , Chen Tsung-Jr , Yang Wen-Luh
Published: November 2022

Organic nonvolatile photomemory devices have drawn considerable attention in the field of optical computing. However, most organic nonvolatile photomemory devices use a charge-trap-type architecture that is complex and difficult to miniaturize. This paper proposes a nonvolatile polyimide (PI) resistive photomemory device with a simple metal–PI–metal configuration; its resistance can be altered using pulsed ultraviolet (UV) irradiation and can be maintained at the altered level even after irradiation has ceased. The resistance can also be returned to the initial state by subsequent irradiation with UV light. The memory window is around 7 order of magnitude. Fourier-transform infrared spectroscopy and UV–visible/near-infrared spectroscopy demonstrated that UV irradiation caused a high-energy-gap (Eg) aromatic form of PI to transform into low-Eg quinoid form, prompting the dominant conduction mechanism of the photomemory device to change from hopping conduction to ohmic conduction. A model characterizing the PI-based photomemory device was also developed and is discussed herein.
Leakage current reduction in β-Ga2O3 Schottky barrier diode with p-NiOx guard ring
Authors: Hong Yue-Hua , Zheng Xue-Feng , He Yun-Long , Zhang Hao , Yuan Zi-Jian , Zhang Xiang-Yu , Zhang Fang , Wang Ying-Zhe , Lu Xiao-Li , Mao Wei , Ma Xiao-Hua , Hao Yue
Published: November 2022

A β-Ga2O3 Schottky barrier diode (SBD) with a p-type NiOx guard ring was fabricated, and the reverse leakage and subthreshold leakage current reduction was found at high temperatures from temperature-dependent I–V characteristics. The functional mechanisms of NiOx as edge termination on leakage reduction were studied. NiOx can increase the barrier height and passivate the defects at the interface, resulting in the suppression of subthreshold leakage and elimination of current crowding effect confirmed by a thermal emission microscope. From the temperature-dependent x-ray photoelectron spectroscopy characteristics, more holes generated to deplete Ga2O3 at higher temperatures were found. It leads to reduce the reverse leakage current. The small-polaron transportation in NiOx is proposed to argue the implausibility of the leakage conduction in NiOx. This work will offer critical physical insight and a valuable route for developing low-leakage Ga2O3 SBDs.
Temperature dependence of current response to sub-terahertz radiation of AlGaN/GaN and graphene transistors
Authors: Rehman A. , Delgado-Notario J. A. , Sai P. , But D. B. , Prystawko P. , Ivonyak Y. , Cywinski G. , Knap W. , Rumyantsev S.
Published: November 2022

The current response to sub-terahertz radiation was studied experimentally over a wide range of temperatures for AlGaN/GaN and graphene transistors. It was found that the responsivity is enhanced at low temperatures by about an order of magnitude for AlGaN/GaN and more than two orders of magnitude for graphene transistors. However, the responsivity increase saturates at temperatures below 70–100 K. These results were explained by the temperature dependence of the charge carriers' mobility, which plays a dominant role in the current responsivity. It is also shown that in a realistic device, the access resistance may decrease the current responsivity, and in the case of high access resistance, the subthreshold swing may also affect the current responsivity. These results showed that extremely high carriers' mobility in graphene makes it very promising for high-frequency detectors.
T cell and B cell antigen receptors share a conserved core transmembrane structure
Authors: Ramesh Samyuktha , Park Soohyung , Im Wonpil , Call Melissa J. , Call Matthew E.
Published: November 2022

The B cell and T cell antigen receptors (BCR and TCR) share a common architecture in which variable dimeric antigen-binding modules assemble with invariant dimeric signaling modules to form functional receptor complexes. In the TCR, a highly conserved T cell receptor αβ (TCRαβ) transmembrane (TM) interface forms a rigid structure around which its three dimeric signaling modules assemble through well-characterized polar interactions. Noting that the key features stabilizing this TCRαβ TM interface also appear with high evolutionary conservation in the TM sequences of the membrane immunoglobulin (mIg) heavy chains that form the BCR’s homodimeric antigen-binding module, we asked whether the BCR contained an analogous TM structure. Using an unbiased biochemical and computational modeling approach, we found that the mouse IgM BCR forms a core TM structure that is remarkably similar to that of the TCR. This structure is reinforced by a network of interhelical hydrogen bonds, and our model is nearly identical to the arrangement observed in the just-released cryo-electron microscopy (cryo-EM) structures of intact human BCRs. Our biochemical analysis shows that the integrity of this TM structure is vital for stable assembly with the BCR signaling module CD79AB in the B cell endoplasmic reticulum, and molecular dynamics simulations indicate that BCRs of all five isotypes can form comparable structures. These results demonstrate that, despite their many differences in composition, complexity, and ligand type, TCRs and BCRs rely on a common core TM structure that has been shaped by evolution for optimal receptor assembly and stability in the cell membrane.
Basaltic reservoirs in the Earth’s mantle transition zone
Authors: Tauzin Benoit , Waszek Lauren , Ballmer Maxim D. , Afonso Juan Carlos , Bodin Thomas
Published: November 2022

The formation and preservation of compositional heterogeneities inside the Earth affect mantle convection patterns globally and control the long-term evolution of geochemical reservoirs. However, the distribution, nature, and size of reservoirs in the Earth’s mantle are poorly constrained. Here, we invert measurements of travel times and amplitudes of seismic waves interacting with mineralogical phase transitions at 400–700-km depth to obtain global probabilistic maps of temperature and bulk composition. We find large basalt-rich pools (up to 60% basalt fraction) surrounding the Pacific Ocean, which we relate to the segregation of oceanic crust from slabs that have been subducted since the Mesozoic. Segregation of oceanic crust from initially cold and stiff slabs may be facilitated by the presence of a weak hydrated layer in the slab or by weakening upon mineralogical transition due to grain-size reduction.
CTLA-4 on thymic epithelial cells complements Aire for T cell central tolerance
Authors: Michelson Daniel A. , Benoist Christophe , Mathis Diane
Published: November 2022

Medullary thymic epithelial cells (mTECs) are essential for the establishment of T cell central tolerance. The transcription factor Aire plays a key role in this process, but other factors remain understudied. We found that a small population of mTECs expressed the coinhibitory receptor cytotoxic T lymphocyte-associated protein 4 (CTLA-4). These CTLA-4
+
cells were detectable in perinates, peaked around young adulthood and expanded sixfold in the absence of Aire. Single-cell transcriptomics revealed CTLA-4
+
mTECs to express a distinct gene signature encoding molecules associated with antigen presentation and interferon-gamma signaling. Mice conditionally lacking CTLA-4 in thymic epithelial cells had no major immunological deficiencies but displayed a mildly increased inflammatory tone and a partial defect in the generation of Foxp3
+
CD4
+
regulatory T cells. Consequently, these mice developed modest levels of autoantibodies and lymphocytic infiltration of peripheral tissues. Thus, CTLA-4 expression in mTECs complements Aire to establish T cell central tolerance.
Unique peptidic agonists of a juvenile hormone receptor with species-specific effects on insect development and reproduction
Authors: Tumova Sarka , Milacek Matej , Šnajdr Ivan , Muthu Magesh , Tuma Roman , Reha David , Jedlicka Pavel , Bittova Lenka , Novotna Adela , Majer Pavel , Sedlak David , Jindra Marek
Published: November 2022

Juvenile hormones (JHs) control insect metamorphosis and reproduction. JHs act through a receptor complex consisting of methoprene-tolerant (Met) and taiman (Tai) proteins to induce transcription of specific genes. Among chemically diverse synthetic JH mimics (juvenoids), some of which serve as insecticides, unique peptidic juvenoids stand out as being highly potent yet exquisitely selective to a specific family of true bugs. Their mode of action is unknown. Here we demonstrate that, like established JH receptor agonists, peptidic juvenoids act upon the JHR Met to halt metamorphosis in larvae of the linden bug,
Pyrrhocoris apterus
. Peptidic juvenoids induced ligand-dependent dimerization between Met and Tai proteins from
P. apterus
but, consistent with their selectivity, not from other insects. A cell-based split-luciferase system revealed that the Met–Tai complex assembled within minutes of agonist presence. To explore the potential of juvenoid peptides, we synthesized 120 new derivatives and tested them in Met–Tai interaction assays. While many substituents led to loss of activity, improved derivatives active at sub-nanomolar range outperformed hitherto existing peptidic and classical juvenoids including fenoxycarb. Their potency in inducing Met–Tai interaction corresponded with the capacity to block metamorphosis in
P. apterus
larvae and to stimulate oogenesis in reproductively arrested adult females. Molecular modeling demonstrated that the high potency correlates with high affinity. This is a result of malleability of the ligand-binding pocket of
P. apterus
Met that allows larger peptidic ligands to maximize their contact surface. Our data establish peptidic juvenoids as highly potent and species-selective novel JHR agonists.
Semitransparent thermophotovoltaics for efficient utilization of moderate temperature thermal radiation
Authors: Burger Tobias , Roy-Layinde Bosun , Lentz Rebecca , Berquist Zachary J. , Forrest Stephen R. , Lenert Andrej
Published: November 2022

Recent advances in thermophotovoltaic (TPV) power generation have produced notable gains in efficiency, particularly at very high emitter temperatures. However, there remains substantial room for improving TPV conversion of waste, solar, and nuclear heat streams at temperatures below 1,100°C. Here, we demonstrate the concept of transmissive spectral control that enables efficient recuperation of below-bandgap photons by allowing them to transmit through the cell to be absorbed by a secondary emitter. We fabricate a semitransparent TPV cell consisting of a thin InGaAs–InP heterojunction membrane supported by an infrared-transparent heat-conducting substrate. The device absorbs less than 1% of below-bandgap radiation, resulting in a TPV efficiency of 32.5% at an emitter temperature of 1,036°C. To our knowledge, this represents an 8% absolute improvement (~33% relative) in efficiency relative to the best TPV devices at such low temperatures. By enabling near-zero photon loss, the semitransparent architecture facilitates high TPV efficiencies over a wide range of applications.
Effects of changes in spacing on dual-script sign
legibility
Authors: Zhang Yuchan , Moys Jeanne-Louise
Published: November 2022

This study examined changes to typographic variables in
Chinese-English traffic signs. Particularly, it considered the effect of
connecting spacing – the vertical distance between a Chinese legend and its
English translation – on reading performance for participants who read English
but not Chinese. Participants were shown driving video simulations, featuring
four connecting space measures (1/6H, 1/3H, 1/2H, 3/4H where H is the height of
one Chinese character) and asked to indicate directions. A threshold method with
an accuracy check was applied. The study demonstrated that connecting spacing
affected participants’ reading performance and is an important consideration for
dual-script sign legibility.
Social Equity and Airbnb: A Response to Litigation Pressures
Authors: Slocum Susan L.
Published: November 2022

This case presents the challenges facing organizations within the sharing economy as they struggle to become more socially inclusive. After describing corporate social responsibility (CSR), specifically social equity, a case study of Airbnb is provided. Using Caroll’s (1991) pyramid of CSR adoption, it is argued that Airbnb remains in-between the economic and legal responsibility platforms, where the CSR initiatives are driven by increased competition in the accommodation sector and legal sanctions placed on the company through discrimination lawsuits.
Temporal and spatial metabolite dynamics impart control in adipogenesis
Authors: Eckel-Mahan Kristin
Published: November 2022

The process of adipogenesis is critical for forming new, healthy adipocytes that are capable of storing lipids. In this issue, Sánchez-Ramírez and Ung et al. (2022. J. Cell Biol.https://doi.org/10.1083/jcb.202111137) reveal a novel role for the metabolite nicotinamide adenine dinucleotide in controlling differentiation of mesenchymal stromal cells into adipocytes.
What happens next? Free fall revisited questions
Authors: Featonby David
Published: November 2022

Looking again at previous experiments with extensions that extend your understanding. Seeing how free fall affects some standard operations.
Application of Fourier-Bessel expansion and LSTM on multi-lead ECG for cardiac abnormalities identification
Authors: Sawant Nidhi Kalidas , Patidar Shivnarayan
Published: November 2022

Objective. The availability of online electrocardiogram (ECG) repositories can aid researchers in developing automated cardiac abnormality diagnostic systems. Using such ECG repositories, this study aims to develop an algorithm that can assist physicians in diagnosing cardiac abnormalities. Approach. The PhysioNet/CinC 2021 Challenge has opened the venues for creating benchmark algorithms using standard and relatively diverse 12-lead ECG datasets. This work attempts to create a new machine learning approach for identifying common cardiac abnormalities using an ensemble-based classification with two models resulting from two different feature sets. The first feature set extracts RR variability based information by deploying Fourier-Bessel (FB) expansion. The second feature set is composed of time- and frequency-domains-based hand-crafted features. Two long short-term memory (LSTM)-based classifiers are trained using these two feature sets as input to categorize ECG signals. Predictions from these two models are fused to arrive at a final medical decision that improves the multi-label classification of the given ECG signals into twenty-six categories. Main results. We participated in the George B. Moody Physionet Challenge 2021 as team ’Medics’, and the proposed methodology was evaluated for all five lead combinations. The challenge scoring metrics obtained on the test data for twelve-, six-, four-, three-, and two-leads combinations are 0.360, 0.368, 0.376, 0.323, and 0.381, respectively. The proposed methodology was ranked 11th among all the follow-up entries of the Challenge. Significance. The obtained results of the proposed method justify the use of an ensemble classifier developed using the extracted feature sets for devising a diagnostic system for detecting and identifying common cardiac problems.
Advancing descriptor search in materials science: feature engineering and selection strategies
Authors: Hoock Benedikt , Rigamonti Santiago , Draxl Claudia
Published: November 2022

A main goal of data-driven materials research is to find optimal low-dimensional descriptors, allowing us to predict a physical property, and to interpret them in a human-understandable way. In this work, we advance methods to identify descriptors out of a large pool of candidate features by means of compressed sensing. To this extent, we develop schemes for engineering appropriate candidate features that are based on simple basic properties of building blocks that constitute the materials and that are able to represent a multi-component system by scalar numbers. Cross-validation based feature-selection methods are developed for identifying the most relevant features, thereby focusing on high generalizability. We apply our approaches to anab initiodataset of ternary group-IV compounds to obtain a set of descriptors for predicting lattice constants and energies of mixing. In particular, we introduce simple complexity measures in terms of involved algebraic operations as well as the amount of utilized basic properties.
Coherent Time-domain Canceling of Interference for Radio Astronomy
Authors: Ellingson S. W. , Buehrer R. M.
Published: November 2022

Radio astronomy is vulnerable to interference from a variety of anthropogenic sources. Among the many strategies for mitigation of this interference is coherent time-domain canceling (CTC), which ideally allows one to “look through” interference, as opposed to avoiding the interference or deleting the afflicted data. However, CTC is difficult to implement, not well understood, and at present this strategy is not in regular use at any major radio telescope. This paper presents a review of CTC including a new comprehensive study of the capabilities and limitations of CTC using metrics relevant to radio astronomy, including fraction of interference power removed and increase in noise. This work is motivated by the emergence of a new generation of communications systems which pose a significantly increased threat to radio astronomy and which may overwhelm mitigation methods now in place.
Evaluation of thermal management scheme of engine cowl based on rotating heat pipe
Authors: Du Chenhui , Huang Degang
Published: November 2022

During the flight in icing conditions, ice may accrete on the aircraft engine cowl, and once it falls off, it will seriously affect the engine performance and even the flight safety of the aircraft. The rotating heat pipe performances good heat transfer characteristics in high-speed rotating conditions, and can be coupled with the high-speed rotating main shaft of the engine to implement the reuse of the engine waste heat for anti-icing of engine cowl. A certain type of engine cowl was selected in the paper, and the anti-icing area and heat load of the three-dimensional cowl were determined using CFD method. On this basis, literature researches were carried out, and feasibility of rotating heat pipe applicated on engine cowl was verified by the qualitative analysis of the rotating heat pipe’s thermal characteristics. Furtherly, based on the anti-icing requirements of the cowl, a rotating heat pipe was designed. Through the thermal experiment, the results show that the rotating heat pipe performs good thermal start-up and stability within 200W, and can meet the anti-icing demands of the engine cowl. From the qualitative and quantitative analysis, it can be convinced that the application of rotating heat pipe on thermal management of the engine cowl is feasible.
Design and analysis of an automatic cable reel for multiple cable connections
Authors: Liu Jiazeng , Liu Xin , Li Haozhang
Published: November 2022

The cable reels are widely used in highly mobile radars. The working efficiency and reliability of the traditional cable reels are not enough in the cases that the number of the cables is large and the power is high. A novel automatic cable reel is developed to provide a reliable and compact operating device for the radar cables. This paper describes the mechanical design of the winch unit and connection unit of the cable reel, which can automatically wind cables and join or separate the electrical connectors, respectively. The power of the motor is determined and the specifications of the system is presented. Then, the cable reel system is analysed and tested. The modal analysis of the system is conducted. The functions that the automatic cable reel can wind the cables, join and separate the electrical connectors efficiently are verified by the experiment results. Compared with the ordinarily manual cable reels or the slip rings, the automatic cable reel developed in this paper is innovative to realize the automation of the separation and joint of the connectors while winding the cables simultaneously, which can promote the efficiency and the reliability of the highly mobile radars, without twining and knotting the cables or wearing the slip rings, especially for multiple and high-power cable connections in limited spaces.
Flow field analysis and structural improvement for a polyacrylonitrile spinneret
Authors: Nie Zhengwei , Chen Ye , Bai Kangqiao
Published: November 2022

Polyacrylonitrile (PAN)-based carbon fibers have high strength, high elongation, and low volume fraction of voids. The precursors of PAN-based carbon fibers are produced by wet or dry jet spinning techniques. To obtain high-quality PAN precursors, the flow field inside a redesigned rectangular spinneret was investigated in this work. The influence of the perforated area ratio of outer holes to inner holes and the fillet diameter of corner holes on the axial velocity distribution before the spinneret plate was discussed. An orthogonal experiment was carried out to acquire optimized structural parameters of the rectangular distributor. After the optimization, the CV of the axial velocity on the observation cross-section decreases from 62.26% to 47.61%.
Structural design and simulation of polymer microfluidic chip bonding device
Authors: Zhi Guosen , Li Jing , Yang Jiong , Li Hui
Published: November 2022

Bonding technology is a key step in the fabrication process of microfluidic chips. Bonding efficiency is one of the difficulties hindering the rapid mass production of microfluidic chips. In order to improve the bonding efficiency of polymer microfluidic chip bonding device. Analysis of process flow based on thermocompression bonding, the hot-pressing bonding device was designed and simulated. In the aspect of structural design: Creo software was used to establish a three-dimensional model, and the traditional heating method was changed to upper heating; Optimize process flow by adding gripper parts and chip library parts. The bonding efficiency was improved by 31.1%. In the aspect of simulation analysis, the model was imported into the simulation software ANSYS, and the influence of TEC location distribution, the thickness of thermal conductive adhesive and the thickness of thermal insulation layer on the temperature uniformity of the bonding zone were studied by numerical simulation. According to the simulation results, the optimal parameters are selected for experimental verification. The results show that this structure parameter can effectively improve the temperature uniformity and reduce the temperature difference in the bonding area to 0.5°C. It provides a new idea for the structural design and optimization of polymer microfluidic chip bonding equipment.
Optimum design for wavy fin tube in an air cooler with genetic algorithm
Authors: Zhou Lingmin , Sui Yongfeng , Lan Jibin , Chu Peng , Liu Yujun , Feng Bin , Du Liheng
Published: November 2022

A strategy by multi-objective genetic algorithm (MOGA) combined with Kriging response surface is proposed for optimum design of wavy fin tube in an air cooler, while minimum pressure loss factor, maximum heat transfer factor and overall performance factor as three objective functions. The results show that the effects of fin height and fin density on the overall performance are positive and the wave number and wave angle are negative; The overall performance of parallel fin is higher than staggered fin; The overall performance of small pipe diameter of wave fin is higher than big pipe diameter; The overall performance reaches the optimum as fin height is 20.7 mm, fin density is 9.9, wave number is 11, wave angle is 4°; The multi-objective genetic algorithm combined with Kriging response surface eliminates the dependence on empirical relation. The results can be used to guide the optimum design of wavy fin tube.
Flow calibration method for gas-liquid two-phase flow of Coriolis flowmeter based on LSTM
Authors: Lu Jiamin , Liu Li , Chen Guoyu , Li Jinjin , Li Cheng , Liu Yajun
Published: November 2022

Measuring with Coriolis flowmeter under the condition of gas-liquid two-phase flow, the vibration signal frequency, phase and amplitude of the measuring pipe fluctuate randomly. The traditional phase difference extraction algorithm is difficult to ensure the measurement accuracy of mass flow. In order to improve the extraction accuracy of mass flow, this paper presents a dynamic error correction method of mass flow based on LSTM (Long Short-Term Memory). The water flow test platform and data acquisition system are built, and the mass flow corrected by this method is compared with the mass flow corrected by ARMA (Autoregressive moving average) model and the mass flow obtained by flow meter. The experimental results show that the mean error of mass flow corrected by this method is 0.0357, and the variance is 0.0453, which is far less than the static error correction of 0.0988 and 0.1068, and far less than the mass flow meter of 0.3816 and 0.4045.
Study on the calibration and uncertainty evaluation of direct-reading atmospheric samplers by laminar flow differential pressure mass flowmeter
Authors: Wang Lei , Qi Rundong , Gao Feng , Zhao Liu , Liu Li , Zhang Qian , Wu Bo , Jie Hui
Published: November 2022

Air sampler is an important measuring instrument for environmental monitoring. With the rapid development of environmental protection industry, the direct reading air sampler has been widely used and this is also related to the improved develop rate of new products. As it only aims at the situation that the standard meter is soap film flowmeter and the measured meter is rotor air sampler, the JJG 956-2013 metrological verification regulation for air sampler is not applicable to the direct reading air sampler. Meanwhile, the corresponding standard meters are also developing rapidly and more results showed that the laminar differential pressure mass flowmeter has more advantages than the soap film flowmeter in the regulation. It can not only improve calibration efficiency, but also realize automatic calibration or remote calibration. In this paper, the method of calibrating direct reading air sampler by laminar flow differential pressure mass flowmeter is studied. The mathematical model of flow rate and relative indication error used in the calibration condition is proposed, and the uncertainty of indication error is also analyzed in detail. In addition, the evaluation example is given accordingly, which fills the blank in the regulation.
State-of-charge estimation for lithium-ion batteries based on dual extended Kalman filter
Authors: Wei Ying
Published: November 2022

The strategy of estimating SOC by model is highly dependent on the accuracy of model. An SOC estimation method based on a dual extended Kalman fliter (DEKF) is proposed. One of the dual filters is employed to estimate the battery SOC, and the other is used to online identify the model parameters. The SOC estimation results by DEKF are compared with those by single EKF under the US06 Highway Driving Schedule test and Dynamic Stress Test (DST). The comparison results show that DEKF has higher SOC estimation and voltage prediction accuracy. Under the US06 and DST tests, the SOC mean absolute error (MAE) decreases from 2.57% and 3.00% to 1.18% and 1.56%, and the MAE of voltage prediction decreases from 54.6 mV and 38.3 mV to 43.9 mV and 29.1 mV, respectively. The SOC estimation and voltage prediction results demonstrate the effectiveness and accuracy of the proposed method.
Simulation research on sliding mode PID control of Buck converters with improved approaching law
Authors: Yang Mu , Chen Jing , Zhang Meng , You Siyilang
Published: November 2022

To solve the problem that Buck converters under traditional control strategies will be affected by various disturbances, resulting in poor stability, a new sliding mode PID control strategy based on improved power exponential reaching law is proposed. The sliding mode PID control model of Buck converter is constructed by using the state space average method. On this basis, the traditional reaching law is improved, and the system equivalent control expression of the improved reaching law is obtained by calculation. Finally, according to the equivalent control expression, the control models are built in Matlab/Simulink simulation software, and compared with the PWM-based sliding mode PID control strategy. The simulation results show that the controller with improved reaching law can effectively reduce chattering, steady-state error and overshoot of the system. Besides, the improved controller can make the robustness of the system better.
Modified RD algorithm of highly squint SAR imaging based on range walk removal
Authors: Tang Chuanbin , Cui Kaibo , Li Yueli , Wang Qingping , Shi Qingzhan , Yuan Naichang
Published: November 2022

In highly squint SAR imaging mode, linear range walk (LRW) plays a leading role in range cell migration (RCM), which is much larger than range bending. Based on the geometric model of highly squint SAR imaging, the characteristics of highly squint SAR echoes are analyzed in this paper. And a modified range-Doppler (RD) algorithm is derived, which is suitable for highly squint mode. The algorithm expands the slant distance to the cubic term, correct linear range walk in the time domain, and correct the range bending in the frequency domain. The simulation results of the point targets verify the feasibility of the algorithm. By comparing with the algorithm before the improvement, the effectiveness of the proposed algorithm is proved.
Current and temperature-rise effect of contact condition for connection terminals in UHVDC converter stations
Authors: Yang Guohua , Yang Junchao , Wang Shengfu , Fu Jianghao , You Yi
Published: November 2022

The heating phenomenon of connector terminals in converter stations has become increasingly common, it has become a serious safety hazared affecting the operation of UHV lines. This paper determined the overlapping model of Al plate-Al plate based on the heating phenomenon of connector terminals in converter stations, conducted the tests which included disassembly and assembly contact surface roughness impact test, pressing force impact test, operation impact test, electric composite grease impact test, anti-loosening measure impact test. Analyzed the main influencing factors of current and temperature-rise for connector terminals heating, and analyzed the influence rule of each factor for current and temperature-rise of connector terminals. Test shows that: bolt tightening torque and electric composite grease was the main influencing factors for current and temperature-rise of connector terminals, and bolt tightening moment was the first main factor, bolt looseness and the performance degradation of electric composite grease directly causes an increase in the contact resistance and temperature rise level of the connector terminals.
Study on NO2 gas sensitivity of metal phthalocyanine enhanced by graphene quantum dots
Authors: Lu Zhizhong , Jiang Menglin , Huang Jieshi , Zhou Xinlei , Li Kejie , Zheng Yue , Jiang Wenkai , Zhang Tao , Yan Hangbing , Xia Huan
Published: November 2022

Traditional semiconductor gas sensors mainly based on metal oxides have some problems such as high working temperature, high energy consumption, low sensitivity, poor anti-interference ability and poor selectivity. Organic semiconductors, represented by metal phthalocyanine (MPc), are becoming the choice of new semiconductor gas sensors because of their advantages of abundant raw materials, low cost, simple process, strong compatibility and ability to work at room temperature. In this study, metal phthalocyanine (molecular diameter of about 1.3 nm) and graphene quantum dots (diameter distribution of 1-3 nm) are similar in size, which facilitates the construction of conjugated plane structure to achieve rapid charge transfer within the material, thus realizing the ultra-sensitive response of the sensor to specific gas molecules at room temperature. In this work, ethylenediamine was used as adhesive to bond tetracarboxylic metal phthalocyanine (MPc-COOH) and graphene quantum dots (GQDs) to form a new composite material MPc-GQD. The response value of the sensor to 100 ppm NO2 gas can reach 19.8 in 100 s at room temperature, and it has good recovery and repeatability under the premise of laser-assisted recovery. The results provide a new idea for the development of room temperature gas sensors using organic semiconductors and carbon nanomaterials.
Comparative study of phase difference extraction methods in the background of Coriolis mass flow meters application
Authors: Lu Jiamin , Wang Ping , Wan Yong , Chen Guoyu , Liu Yajun , Wang Liya
Published: November 2022

Coriolis mass flow meter is widely used in industrial production due to their high precision and high stability. When the traditional phase difference extraction algorithm is used to extract the phase difference, Because of the influence of spectrum leakage, environmental noise and interference, the extraction error of the algorithm increases by using of traditional phase difference extraction algorithms. To improve the accuracy of phase difference extraction, an improved correlation analysis method is proposed in this paper. The improved correlation analysis method combines the Hilbert transform. First, the signals at both ends of the sensor are superimposed, and then the Hilbert transform is performed to form a reference signal, and finally the correlation analysis method is used to solve the phase difference between the original signal and the reference signal. Through simulation experiments, comparing the phase difference extraction accuracy of the improved correlation analysis method with other traditional methods, the improved correlation analysis method has higher measurement accuracy and better stability.
Nonparametric nonlinear profile monitoring method for machine condition monitoring
Authors: Deng Yanqing , Hou Bingchang , Chen Yikai , Wang Dong
Published: November 2022

Machine condition monitoring (MCM) aims to evaluate machine health conditions by statistically analysing machine condition data. Health indicators (HIs) such as Gini index, negative entropy, spectral kurtosis et al. have been commonly applied in MCM. But these HIs lack a statistical threshold and monotonic degradation tendency. To monitor the health condition of rotating machines, a nonparametric nonlinear profile monitoring method for MCM is proposed in this paper. And a Hotelling T-square health indicator (HTHI) with a statistical threshold is constructed with B-spline modeling and Hotelling T-square statistic. Experimental validation on a public bearing dataset shows that the constructed HTHI can effectively detect early machine faults and monotonically evaluate degradation trends, which enriches methods of MCM domain.
Navigating sustainability and health trade-offs in global seafood systems
Authors: Robinson James P W , Garrett Angus , Paredes Esclapez Juan Carlos , Maire Eva , Parker Robert W R , Graham Nicholas A J
Published: November 2022

Seafood is expected to play a key role in improving access to healthy diets while providing food products with relatively low rates of greenhouse gas emissions. However, both nutrients and carbon footprints vary among species and production methods, and seafood consumption is further influenced by price and consumer preference, such that it is unclear which species are best placed to provide low-emissions nutritious seafood. Here, we use seafood production data to assess the nutritional value, carbon emissions, sustainability, affordability, and availability of seafood available to UK consumers. Globally, most seafood products are more nutritious and emit lower greenhouse gases than terrestrial animal-source foods, particularly small pelagic fishes and bivalves that contributed to recommended intakes for 3–4 essential dietary nutrients at the lowest emissions. For seafood products relevant to UK markets and consumers, Atlantic mackerel had the highest availability (i.e. landings) of all wild-caught UK seafood and lowest carbon footprint of all finfish, with one fillet portion exceeding recommended intakes of three nutrients (selenium, vitamins B12 and D). We found that price and sustainability of UK seafood, both factors in consumer demand, had considerable trade-offs with nutrients, carbon footprint, and availability. Farmed salmon, for example, were produced in large volumes but were relatively more expensive than other seafood, whereas highly nutritious, low-emissions farmed mussels had limited production volumes. The UK’s seafood system is therefore not currently optimised to produce nutritious, low-emissions seafood in large amounts. Policies that promote local consumption of affordable species already produced in high volumes, such as mackerel, could improve intakes of nutrients that are deficient in the UK population at relatively low environmental cost.
Asymptotic dynamics of higher-order lumps in the Davey–Stewartson II equation
Authors: Guo Lijuan , Kevrekidis P G , He Jingsong
Published: November 2022

A family of higher-order rational lumps on non-zero constant background of Davey–Stewartson (DS) II equation are investigated. These solutions have multiple peaks whose heights and trajectories are approximately given by asymptotical analysis. It is found that the heights are time-dependent and for large time they approach the same constant height value of the first-order fundamental lump. The resulting trajectories are considered and it is found that the scattering angle can assume arbitrary values in the interval of

(

π
2

,
π
)

which is markedly distinct from the necessary orthogonal scattering for the higher-order lumps on zero background. Additionally, it is illustrated that the higher-order lumps containing multi-peaked n-lumps can be regarded as a nonlinear superposition of n first-order ones as

|

t

|

→
∞

.
Electrochemical characterization of hexamethylguanidinium bis(fluorosulfonyl)imide [HMG][FSI] based electrolyte and its application in sodium metal batteries
Authors: Biernacka Karolina , Sun Ju , Makhlooghiazad Faezeh , Balkis Ali , Gunathilaka Isuru E , O’Dell Luke A , Mestres Montserrat Galceran , Howlett Patrick C , Pringle Jennifer M , Forsyth Maria
Published: November 2022

With the increasing energy demand for both electronic portable devices and energy storage for fluctuating renewable energy sources, there is a strong need for alternatives beyond lithium batteries. Sodium batteries have been attracting great attention recently due to the abundance and low supply cost of the raw materials. However, they require highly conductive, safe and electrochemically stable electrolytes in order to enable their practical realization. In this work we present the promising physicochemical properties of the electrolyte based on hexamethylguanidinium bis(fluorosulfonyl)imide [FSI] at a sodium concentration of 25 mol% NaFSI. The liquid-state electrolyte supports stable Na plating and stripping at 1 h polarization times at 0.5 mA cm−2 current density in a Na symmetrical coin cell at 50 °C, maintaining a low polarization potential of ≈45 mV throughout 160 cycles. Moreover, this electrolyte is characterized by relatively high Na-ion transference number of 0.36 ± 0.03 at 50 °C. A long cycle life of 300 cycles with 285 mAh g−1 is achieved in a half cell set up with hard carbon. The solid-electrolyte interphase layer on the anode, which contributes to this high capacity, is investigated by x-ray photoelectron spectroscopy and solid-state nuclear magnetic resonance spectroscopy. The long-term cycling performance of Na|NaFePO4 cell is also demonstrated with a high specific capacity of 106 mAh g−1 and 80% capacity retention after 110 cycles.