bluuebunny/crossref_metadata_2025 huggingface dataset:
Dynamics-disentangled deep learning model for multi-cycle prediction of unsteady flow field
Authors: Qu Xiyao , Liu Zijing , An Wei , Liu Xuejun , Lyu Hongqiang
Published: August 2022

The prediction of an unsteady flow field inherently involving high-dimensional dynamics is challenging. The multi-cycle prediction is especially difficult due to the inevitably accumulated errors over time. A novel deep learning model is proposed in this paper to disentangle the high-dimensional dynamics into two separate attributes that, respectively, represent spatial and temporal dynamics. A continuous mapping of temporal dynamics is subsequently constructed, which alleviates the error accumulation and, thus, contributes to the long-term prediction of the unsteady flow field. The dynamics-disentangled deep learning model (D3LM) processes sequential image data of the unsteady flow field and is constituted by three sub-networks, an encoder introducing a stochastic latent variable to explicitly model the low-order temporal dynamics (called varying attribute herein) and extracting multi-level representations of spatial dynamics (called consistent attribute herein), a decoder integrating the disentangled attributes and generating a future flow field, and a discriminator improving the quality of the predicted flow field. The proposed model is evaluated by two simulated datasets of unsteady flows around a circular cylinder at divergent Reynolds numbers. Benefiting from modeling the continuous distribution of temporal dynamics with the stochastic latent variable, the proposal can give multi-cycle future predictions with high accuracy both spatially and temporally on the two datasets with a small amount of training data. Our work demonstrates the potential practicability of deep learning techniques for modeling the long-term nonlinear laws of unsteady flow.
Transition to hyperchaos: Sudden expansion of attractor and intermittent large-amplitude events in dynamical systems
Authors: Leo Kingston S. , Kapitaniak Tomasz , Dana Syamal K.
Published: August 2022

Hyperchaos is distinguished from chaos by the presence of at least two positive Lyapunov exponents instead of just one in dynamical systems. A general scenario is presented here that shows emergence of hyperchaos with a sudden large expansion of the attractor of continuous dynamical systems at a critical parameter when the temporal dynamics shows intermittent large-amplitude spiking or bursting events. The distribution of local maxima of the temporal dynamics is non-Gaussian with a tail, confirming a rare occurrence of the large-amplitude events. We exemplify our results on the sudden emergence of hyperchaos in three paradigmatic models, namely, a coupled Hindmarsh–Rose model, three coupled Duffing oscillators, and a hyperchaotic model.
Mechanisms of graphite ablation by sub-millisecond ytterbium fiber laser pulses
Authors: Park Minok , Balkey Matthew M. , Mao Xianglei , Jonsson Jacob C. , Grigoropoulos Costas P. , Zorba Vassilia
Published: August 2022

Graphite is a key material in a variety of cross-cutting applications in energy conversion, energy storage, and nuclear energy. Recently, temporally modulated continuous wave lasers have been shown to produce well-defined ablation features in graphite at relatively high processing speeds. In this work, we analyze in detail the laser ablation dynamics of single-pulse ablation in the sub-millisecond time regime to elucidate the origins of the resulting well-defined ablation craters using a combination of time-resolved emission imaging, diffuse reflection/scattering imaging, and optical emission spectroscopy. These multimodal in situ diagnostics revealed three main contributors to achieve well-defined ablation features: (1) rapid ejection of particles with ∼100 m/s speed, (2) ablation of the graphite in the gaseous form, and (3) absence of bulk liquid motion, which is typically observed in laser processing of metals. Plasma plume formation was sustained throughout the duration of the laser pulse (500 μs). This work provides insights into the complex physical and chemical mechanisms of sub-millisecond laser–matter interactions, which are critical for parameter space optimization and tailoring of laser machining and drilling processes.
An experimental investigation on the magnetoviscous effect and shear rate-dependent viscosity of a magnetic suspension under longitudinal and transverse magnetic fields
Authors: Cunha F. R. , Sinzato Y. Z. , Pereira I. D. O.
Published: August 2022

In the present investigation, we report experimental evidence that the magnetoviscous effect of a ferrofluid can be described by a suspension of ellipsoidal particles. The studies are carried out in shear and pipe flows, and comparison with theory for non-spherical particle is made. Flows of this type appear in many applications where magnetic fluids are used as lubricants or magnetic seals. The chain-like aggregates present in the magnetic fluid are modeled as equivalent prolate spheroids. A power-law correlation accounts for the breakup of aggregates due to the shear flow. The viscosity of a real ferrofluid is measured in a parallel disk rheometer with an applied magnetic field parallel to velocity gradient and in a capillary viscometer with a field in the velocity direction. An asymptotic solution for the low Péclet number limit presents an excellent agreement with the experimental results in this regime, while the numerical results provide a good agreement up to moderate values of Péclet. In addition, the numerical results for the non-dimensional viscosity of the fluid and the magnetic increment viscosity are verified by comparing results with the experimental measurements of the same quantities for moderate values of the Péclet number. The relative importance of the mean stresslet and rotlet contributions for the non-dimensional magnetic suspension viscosity is also examined in a regime of low Péclet number. The results also were important to verify our previous theoretical work presented recently in a companion paper Sinzato and Cunha [Phys. Fluids 33, 102006 (2021)] for the regime of Pe < 1.
Quantitative dynamics of paradigmatic SN2 reaction OH− + CH3F on accurate full-dimensional potential energy surface
Authors: Qin Jie , Liu Yang , Li Jun
Published: August 2022

The bimolecular reaction between OH− and CH3F is not just a prototypical SN2 process, but it has three other product channels. Here, we develop an accurate full-dimensional potential energy surface (PES) based on 191 193 points calculated at the level CCSD(T)-F12a/aug-cc-pVTZ. A detailed dynamics and mechanism analysis was carried out on this potential energy surface using the quasi-classical trajectory approach. It is verified that the trajectories do not follow the minimum energy path (MEP), but directly dissociate to F− and CH3OH. In addition, a new transition state for proton exchange and a new product complex CH2F−⋯H2O for proton abstraction were discovered. The trajectories avoid the transition state or this complex, instead dissociate to H2O and CH2F− directly through the ridge regions of the minimum energy path before the transition state. These non-MEP dynamics become more pronounced at high collision energies. Detailed dynamic simulations provide new insights into the atomic-level mechanisms of the title reaction, thanks to the new chemically accurate PES, with the aid of machine learning.
Calcium and magnesium supplementation of ewes grazing pasture did not improve lamb survival
Authors: Robertson Susan M. , McGrath Shawn R. , Scarlett Samuel , Bhanugopan Marie , Hocking Edwards Janelle E. , Winslow Emma , Hancock Serina , Thompson Andrew N. , Refshauge Gordon , Friend Michael A.
Published: August 2022

Context Clinical deficiencies of calcium and magnesium may result in the metabolic disorders hypocalcaemia and hypomagnesaemia, resulting in ewe and lamb mortality. However, the contribution of subclinical deficiencies to perinatal lamb mortality in grazing flocks is unclear. Aims To test the hypothesis that calcium and magnesium supplementation during the lambing period would increase lamb survival to marking age. Methods In 2017, an on-farm study used five flocks across New South Wales, South Australia and Western Australia. On each farm, twin-bearing mature Merino ewes (n = 400–600) grazing pasture were allocated to two replicates of control and supplemented treatments. The supplemented groups were offered 30 g/ewe per day of a loose lick containing magnesium chloride (MgCl2(H2O)6), calcium sulfate (CaSO4·(H2O)2, and salt (NaCl), in the ratio 12.5:32.5:55.0, designed to have a low dietary cation–anion difference (−390 meq/100 g). A second study was conducted in 2018 on one farm to test the form of supplement. This study used two replicates of three treatments: control; a low-dietary cation–anion difference supplement as used in 2017; and a standard lime, Causmag (calcined MgO) and salt loose mix (ratio 1:1:1). Mature twin-bearing composite ewes (n = 600) were allocated to groups and those supplemented were offered minerals for the last month of pregnancy and during the lambing period. Blood and urine samples were collected in both experiments for analyses of mineral concentrations. Key results In the 2017 study, only two flocks consumed >10 g/ewe of supplement per day, and supplementation did not increase lamb survival to marking age in these flocks. In the 2018 study, the mean consumption of supplement was 18 or 20 g/ewe per day. Of non-supplemented ewes, 61% were deficient in plasma calcium (≤90 mg/L) and 17% were deficient in magnesium (≤18 mg/L) at Day 140 after the start of joining. Lamb survival was not increased by supplementation and was 77 ± 3.8% in both treatments. Conclusions Calcium and magnesium supplementation did not increase lamb survival. Implications Lamb survival was not increased by calcium and magnesium supplementation; however, evaluation under a wider range of grazing conditions with adequate supplement intake is required.
Harboured cation/proton antiporters modulate stress response to integrated heat and salt via up-regulating
Authors: Kahraman Nihal , Pehlivan Necla
Published: August 2022

Recent research has pointed to improved salt tolerance by co-overexpression of Arabidopsis thaliana NHX1 (Na+/H+ antiporter) and SOS1 (Salt Overly Sensitive1). However, functionality under salt stress accompanying heat is less understood in double transgenics. To further advance possible co-operational interactions of AtNHX1 (N) and AtSOS1 (S) under combined stress, modulation of osmolyte, redox, energy, and abscisic acid metabolism genes was analysed. The expression of the target BIP3, KIN1, GOLS1, OHP2, and CYCA3;2 in transgenic Arabidopsis seedlings were significantly regulated towards a dramatic suppression by ionic, osmotic, and heat stresses. AtNHX1 and AtSOS1 co-overexpression (NS) outpaced the single transgenics and control in terms of membrane disorganisation and the electrolyte leakage of the cell damage caused by heat and salt stress in seedlings. While NaCl slightly induced CYCA3;2 in transgenics, combined stress up-regulated KIN1 and GOLS1, not other genes. Single N and S transgenics overexpressing AtNHX1 and AtSOS1 only appeared similar in their growth and development; however, different to WT and NS dual transgenics under heat + salt stress. Seed germination, cotyledon survival, and hypocotyl length were less influenced by combined stress in NS double transgenic lines than in single N and S and wild type. Stress combination caused significant reprogramming of gene expression profiles, mainly towards downregulation, possibly as a trade-off strategy. Analysing phenotypic, cellular, and transcriptional responses regulating growth facets of tolerant transgenic genotypes may support the ongoing efforts to achieve combined salt and heat tolerance.
Comparative genomics of mortal and immortal cnidarians unveils novel keys behind rejuvenation
Authors: Pascual-Torner Maria , Carrero Dido , Pérez-Silva José G. , Álvarez-Puente Diana , Roiz-Valle David , Bretones Gabriel , Rodríguez David , Maeso Daniel , Mateo-González Elena , Español Yaiza , Mariño Guillermo , Acuña José Luis , Quesada Víctor , López-Otín Carlos
Published: August 2022

Turritopsis dohrnii
is the only metazoan able to rejuvenate repeatedly after its medusae reproduce, hinting at biological immortality and challenging our understanding of aging. We present and compare whole-genome assemblies of
T. dohrnii
and the nonimmortal
Turritopsis rubra
using automatic and manual annotations, together with the transcriptome of life cycle reversal (LCR) process of
T. dohrnii.
We have identified variants and expansions of genes associated with replication, DNA repair, telomere maintenance, redox environment, stem cell population, and intercellular communication. Moreover, we have found silencing of polycomb repressive complex 2 targets and activation of pluripotency targets during LCR, which points to these transcription factors as pluripotency inducers in
T. dohrnii
. Accordingly, we propose these factors as key elements in the ability of
T. dohrnii
to undergo rejuvenation.
USP13 promotes deubiquitination of ZHX2 and tumorigenesis in kidney cancer
Authors: Xie Haibiao , Zhou Jin , Liu Xijuan , Xu Yawei , Hepperla Austin J. , Simon Jeremy M. , Wang Tao , Yao Hongwei , Liao Chengheng , Baldwin Albert S. , Gong Kan , Zhang Qing
Published: August 2022

Clear cell renal cell carcinoma (ccRCC) is characterized by the loss of tumor suppressor Von Hippel Lindau (VHL) function. VHL is the component of an E3 ligase complex that promotes the ubiquitination and degradation of hypoxia inducible factor α (HIF-α) (including HIF1α and HIF2α) and Zinc Fingers And Homeoboxes 2 (ZHX2). Our recent research showed that ZHX2 contributed to ccRCC tumorigenesis in a HIF-independent manner. However, it is still unknown whether ZHX2 could be modified through deubiquitination even in the absence of pVHL. Here, we performed a deubiquitinase (DUB) complementary DNA (cDNA) library binding screen and identified USP13 as a DUB that bound ZHX2 and promoted ZHX2 deubiquitination. As a result, USP13 promoted ZHX2 protein stability in an enzymatically dependent manner, and depletion of USP13 led to ZHX2 down-regulation in ccRCC. Functionally,USP13depletion led to decreased cell proliferation measured by two-dimensional (2D) colony formation and three-dimensional (3D) anchorage-independent growth. Furthermore, USP13 was essential for ccRCC tumor growth in vivo, and the effect was partially mediated by its regulation on ZHX2. Our findings support that USP13 may be a key effector in ccRCC tumorigenesis.
Manipulating complex chromatin folding via CRISPR-guided bioorthogonal chemistry
Authors: Qin Geng , Yang Jie , Zhao Chuanqi , Ren Jinsong , Qu Xiaogang
Published: August 2022

Precise manipulation of chromatin folding is important for understanding the relationship between the three-dimensional genome and nuclear function. Existing tools can reversibly establish individual chromatin loops but fail to manipulate two or more chromatin loops. Here, we engineer a powerful CRISPR system which can manipulate multiple chromatin contacts using bioorthogonal reactions, termed the bioorthogonal reaction-mediated programmable chromatin loop (BPCL) system. The multiinput BPCL system employs engineered single-guide RNAs recognized by discrete bioorthogonal adaptors to independently and dynamically control different chromatin loops formation without cross-talk in the same cell or to establish hubs of multiway chromatin contacts. We use the BPCL system to successfully juxtapose the pluripotency gene promoters to enhancers and activate their endogenous expression. BPCL enables us to independently engineer multiway chromatin contacts without cross-talk, which provides a way to precisely dissect the high complexity and dynamic nature of chromatin folding.
Behavioral and financial coping strategies among energy-insecure households
Authors: Carley Sanya , Graff Michelle , Konisky David M. , Memmott Trevor
Published: August 2022

When households struggle to pay their energy bills and avoid being disconnected from the grid, they may accrue debt, forgo expenses on food, and use space heaters or ovens to warm their homes. These coping strategies can introduce significant physical and financial risks. In this study, we analyze an original survey with a representative sample of low-income households during the first year of the COVID-19 pandemic, from June 2020 to May 2021. We evaluate the prevalence of a wide range of coping strategies and empirically estimate the determinants of these strategies. We find that more than half of all low-income households engage in at least one coping strategy, and many use multiple strategies. Households with vulnerable members, including young children or those who rely on electronic medical devices, and households that live in deficient housing conditions, are more likely to use a range of coping strategies, and many at once. Our findings have direct implications for public policy improvements, including modifications to the US Weatherization Assistance Program, the Low-Income Home Energy Assistance Program, and state utility disconnection protections.
Different classes of genomic inserts contribute to human antibody diversity
Authors: Lebedin Mikhail , Foglierini Mathilde , Khorkova Svetlana , Vázquez García Clara , Ratswohl Christoph , Davydov Alexey N. , Turchaninova Maria A. , Daubenberger Claudia , Chudakov Dmitriy M. , Lanzavecchia Antonio , de la Rosa Kathrin
Published: August 2022

Recombination of antibody genes in B cells can involve distant genomic loci and contribute a foreign antigen-binding element to form hybrid antibodies with broad reactivity forPlasmodium falciparum. So far, antibodies containing the extracellular domain of the LAIR1 and LILRB1 receptors represent unique examples of cross-chromosomal antibody diversification. Here, we devise a technique to profile non-VDJ elements from distant genes in antibody transcripts. Independent of the preexposure of donors to malaria parasites, non-VDJ inserts were detected in 80% of individuals at frequencies of 1 in 104to 105B cells. We detected insertions in heavy, but not in light chain or T cell receptor transcripts. We classify the insertions into four types depending on the insert origin and destination: 1) mitochondrial and 2) nuclear DNA inserts integrated at VDJ junctions; 3) inserts originating from telomere proximal genes; and 4) fragile sites incorporated between J-to-constant junctions. The latter class of inserts was exclusively found in memory and in in vitro activated B cells, while all other classes were already detected in naïve B cells. More than 10% of inserts preserved the reading frame, including transcripts with signs of antigen-driven affinity maturation. Collectively, our study unravels a mechanism of antibody diversification that is layered on the classical V(D)J and switch recombination.
Revealing *OOH key intermediates and regulating H
2
O
2
photoactivation by surface relaxation of Fenton-like catalysts
Authors: Xu Xiaoming , Zhang Yuanming , Chen Yong , Liu Changhao , Wang Wenjing , Wang Jiajia , Huang Huiting , Feng Jianyong , Li Zhaosheng , Zou Zhigang
Published: August 2022

Hydrogen peroxide (H
2
O
2
) molecules play important roles in many green chemical reactions. However, the high activation energy limits their application efficiency, and there is still huge controversy about the activation path of H
2
O
2
molecules over the presence of *OOH intermediates. Here, we confirmed the formation of the key species *OOH in the heterogeneous system, via in situ shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS), isotope labeling, and theoretical calculation. In addition, we found that compared with *H
2
O
2
, *OOH was more conducive to the charge transfer behavior with the catalyst and the activation of an O-O bond. Furthermore, we proposed to improve the local coordination structure and electronic density of the YFeO
3
catalyst by regulating the surface relaxation with Ti modification so as to reduce the activation barrier of H
2
O
2
and to improve the production efficiency of •OH. As a result, the kinetics rates of the Fenton-like (photo-Fenton) reaction had been significantly increased several times. The •OH free radical activity mechanism and molecular transformation pathways of 4-chloro phenol (4-CP) were also revealed. This may provide a clearer vision for the further study of H
2
O
2
activation and suggest a means of designing catalysts for efficient H
2
O
2
activation.
Multimodal cotranslational interactions direct assembly of the human multi-tRNA synthetase complex
Authors: Khan Krishnendu , Long Briana , Gogonea Valentin , Deshpande Gauravi M. , Vasu Kommireddy , Fox Paul L.
Published: August 2022

Amino acid ligation to cognate transfer RNAs (tRNAs) is catalyzed by aminoacyl-tRNA synthetases (aaRSs)—essential interpreters of the genetic code during translation. Mammalian cells harbor 20 cytoplasmic aaRSs, out of which 9 (in 8 proteins), with 3 non-aaRS proteins, AIMPs 1 to 3, form the ∼1.25-MDa multi-tRNA synthetase complex (MSC). The function of MSC remains uncertain, as does its mechanism of assembly. Constituents of multiprotein complexes encounter obstacles during assembly, including inappropriate interactions, topological constraints, premature degradation of unassembled subunits, and suboptimal stoichiometry. To facilitate orderly and efficient complex formation, some complexes are assembled cotranslationally by a mechanism in which a fully formed, mature protein binds a nascent partner as it emerges from the translating ribosome. Here, we show out of the 121 possible interaction events between the 11 MSC constituents, 15 are cotranslational. AIMPs are involved in the majority of these cotranslational interactions, suggesting they are not only critical for MSC structure but also for assembly. Unexpectedly, several cotranslational events involve more than the usual dyad of interacting proteins. We show two modes of cotranslational interaction, namely a “multisite” mechanism in which two or more mature proteins bind the same nascent peptide at distinct sites and a second “piggy-back” mechanism in which a mature protein carries a second fully formed protein and binds to a single site on an emerging peptide. Multimodal mechanisms of cotranslational interaction offer a diversity of pathways for ordered, piecewise assembly of small subcomplexes into larger heteromultimeric complexes such as the mammalian MSC.
Hydrophilic reentrant SLIPS enabled flow separation for rapid water harvesting
Authors: Guo Zongqi , Boylan Dylan , Shan Li , Dai Xianming
Published: August 2022

Water harvesting from air is desired for decentralized water supply wherever water is needed. When water vapor is condensed as droplets on a surface the unremoved droplets act as thermal barriers. A surface that can provide continual droplet-free areas for nucleation is favorable for condensation water harvesting. Here, we report a flow-separation condensation mode on a hydrophilic reentrant slippery liquid-infused porous surface (SLIPS) that rapidly removes droplets with diameters above 50 μm. The slippery reentrant channels lock the liquid columns inside and transport them to the end of each channel. We demonstrate that the liquid columns can harvest the droplets on top of the hydrophilic reentrant SLIPS at a high droplet removal frequency of 130 Hz/mm2. The sustainable flow separation without flooding increases the water harvesting rate by 110% compared to the state-of-the-art hydrophilic flat SLIPS. Such a flow-separation condensation approach paves a way for water harvesting.
Reintroducing bison results in long-running and resilient increases in grassland diversity
Authors: Ratajczak Zak , Collins Scott L. , Blair John M. , Koerner Sally E. , Louthan Allison M. , Smith Melinda D. , Taylor Jeffrey H. , Nippert Jesse B.
Published: August 2022

The widespread extirpation of megafauna may have destabilized ecosystems and altered biodiversity globally. Most megafauna extinctions occurred before the modern record, leaving it unclear how their loss impacts current biodiversity. We report the long-term effects of reintroducing plains bison (Bison bison) in a tallgrass prairie versus two land uses that commonly occur in many North American grasslands: 1) no grazing and 2) intensive growing-season grazing by domesticated cattle (Bos taurus). Compared to ungrazed areas, reintroducing bison increased native plant species richness by 103% at local scales (10 m2) and 86% at the catchment scale. Gains in richness continued for 29 y and were resilient to the most extreme drought in four decades. These gains are now among the largest recorded increases in species richness due to grazing in grasslands globally. Grazing by domestic cattle also increased native plant species richness, but by less than half as much as bison. This study indicates that some ecosystems maintain a latent potential for increased native plant species richness following the reintroduction of native herbivores, which was unmatched by domesticated grazers. Native-grazer gains in richness were resilient to an extreme drought, a pressure likely to become more common under future global environmental change.
Quality control mechanisms that protect nuclear envelope identity and function
Authors: Mannino Philip J. , Lusk C. Patrick
Published: August 2022

The nuclear envelope (NE) is a specialization of the endoplasmic reticulum with distinct biochemistry that defines inner and outer membranes connected at a pore membrane that houses nuclear pore complexes (NPCs). Quality control mechanisms that maintain the physical integrity and biochemical identity of these membranes are critical to ensure that the NE acts as a selective barrier that also contributes to genome stability and metabolism. As the proteome of the NE is highly integrated, it is challenging to turn over by conventional ubiquitin-proteasome and autophagy mechanisms. Further, removal of entire sections of the NE requires elaborate membrane remodeling that is poorly understood. Nonetheless, recent work has made inroads into discovering specializations of cellular degradative machineries tailored to meeting the unique challenges imposed by the NE. In addition, cells have evolved mechanisms to surveil and repair the NE barrier to protect against the deleterious effects of a breach in NE integrity, in the form of either a ruptured NE or a dysfunctional NPC. Here, we synthesize the most recent work exploring NE quality control mechanisms across eukaryotes.
Study on Interaction Analysis Method between Fog Drops and Tree Trunk Surface for Precision Pesticide Application by Plant Protection UAV
Authors: Jia Yalan , Xiong Wei , Luo Bo , Wang Yue , Liu Shujie , Cheng Ming
Published: August 2022

In order to improve pesticide application efficiency and reduce environmental pollution, precise pesticide application has become the core concept of forestry pest control. In this paper, based on the precise target research requirements of the pesticide liquid of plant protection UAV, the VOF model of droplet impact was established. The two-phase flow model was used to simulate the three processes (contact, spread and contraction) of droplet impact on bark, and analyse the state of droplet impact on bark surface at different speeds and heights. Through the study, the behaviour state of fog droplets in different conditions can be obtained, which can maximize the use of liquid medicine, reduce environmental pollution, and provide a new research method for fog droplets deposition on tree trunk surface.
Modification and Optimization of Cylindrical Blade of Dredge Pump Based on CFD
Authors: Zhuang Haifei , Liu Mingming , Guo Tao
Published: August 2022

The 3500 m3/h series cutter suction dredger pump adopts cylindrical blade impeller with low efficiency and serious wear of impeller channel; The twisted blade is optimized by conformal transformation method, and the blade wrap angle is increased by 75°; The efficiency of dredge pump with twisted blades is increased by 9% compared with cylindrical blades when the flow is 8000-12000 m3/h; The relative velocity nephogram shows that the twisted blade eliminates the vortex in the impeller channel and improves the flow field; Through the erosion simulation analysis of solid-liquid two-phase flow, through the surface equalization treatment of the erosion wear of the impeller wall, it is found that the average wear rate of the twisted blades is 19% lower than that of the cylindrical blades, indicating that the wear resistance of the designed twisted blade impeller has been improved and the service life of the dredge pump has been increased.
Modelling and Simulation of Transverse Homogeneity of Slotted Coating Process
Authors: Wang Jianhong , Zhong Yongchao , Li Yubiao , Wang Xiaodong
Published: August 2022

Slot coating is a kind of precise coating process, which is widely used in the production of membrane materials. The thickness deviation of coating along the transverse direction is the key index to measure the coating quality. The homogeneity of the transverse distribution of the coating velocity at the exit of the die is the most direct factor leading to the transverse thickness deviation of the coating. To predict the transverse homogeneity of slot coating, a mathematical model for the internal flow field in the die was established, where the incompressible Navier-Stokes equations were used to describe the fluid flow and generalized Newtonian fluid model was used to describe the rheological behaviour of non-Newtonian coating. An efficient explicit splitting algorithm based on finite element method is proposed to solve the model. To verify the effectiveness of the model and the algorithm, the internal flow field of a trapezoidal double cavity die with equal section was simulated. The transverse homogeneity obtained was close to the experimental measured value, which verified the validity of the model. Furthermore, the influence of measuring slot width on the transverse homogeneity of outlet velocity is studied, and the simulation results are consistent with the theoretical expectations.
Simulation Analysis of Double-effect Seawater Desalination System Using Compression Heat Pump
Authors: Xiao Yanping , Yuan Hao , Shen Jiubin , Yan Siyuan
Published: August 2022

The lack of freshwater resources has become the biggest obstacle to the sustainable development of the world economy with the expansion of population and the impact of climate change. Seawater desalination is recognized as the most effective means to alleviate water scarcity. A double-effect seawater desalination system using compression heat pump is proposed by combining a compression heat pump and a double-effect desalination system. Performances of the proposed system are simulated using Aspen simulation software. Based on the simulation results, the influence of heat pump evaporating/condensing temperature, temperature difference between the two effects and the brine circulation ratio on the system Performance Ratio (PR) and freshwater production are analysed. It is concluded that the value of PR increases but the freshwater production reduces with the increase of evaporating temperature of the heat pump. Both the value of PR and the freshwater production decreases with the condensing temperature of the heat pump. An optimal temperature difference between the two effects exits to get the highest PR and freshwater production for a constant heat pump operation condition. The freshwater production can increase slightly with the increase of the brine circulation ratio. When the mass flow rate of feed seawater is 80kg/h and the evaporation temperature of primary effect evaporator is 40°C, the PR of the system reaches 40.07 with an evaporating/condensing temperature of 20°C/50°C. The freshwater production is 39.76kg/h with an evaporating/condensing temperature of 10°C/50°C.
Numerical Calculation of Solid-Liquid Two-Phase Flow in Open-Design Vortex Pump
Authors: Gao Xiongfa , Shi Weidong , Wang Junhua , Lu Hongzhong , Wang Jiabin , Meng Wanli , Jin Jiamin
Published: August 2022

This paper mainly based on the CFD platform, numerical simulation of the internal flow field in the open-design vortex pump under different solid particle concentration and particle size is carried out to explore the flow trajectory characteristics of solid particles in the impeller channel and the lateral cavity, as well as the distribution characteristics of solid particles, and calculate the sliding velocity of particles in the impeller channel. The results show that at different solid particle concentrations, the solid volume fraction f in the front and rear cover plate area of the blade is high and that in the middle area is low; The solid volume fraction f decreases gradually from the working face to the back, and the solid particles are widely distributed in the inlet area. Due to the asymmetry of the volute structure, the particle concentration in the inlet area corresponding to the casing tongue is significantly higher than that in other areas; Due to the existence of circulating flow and through flow, the solid particles are distributed in a circular direction in the lateral cavity, and the particle concentration in the middle region is large; In the impeller area corresponding to the casing tongue, the sliding velocity of solid particles decreases with the increase of particle size, and the sliding velocity values of 0.5mm and 1.0mm particle sizes are close.
Fault Analysis and Elimination of Hydraulic Driving System for Rubber Rig in Coal Mine
Authors: Chen Fenglei
Published: August 2022

Aiming at the failure of the rubber wheel drilling rig with unstable walking speed during use, the principle of the walking hydraulic system is introduced, the cause of the failure is analyzed, and the principle of first easy and then difficult, first observation and then dismantling and inspection is followed. According to the output pressure of the differential valve block and the output characteristics of the hydraulic pump, combined with the principle of the hydraulic travel system, it is finally determined that the internal leakage of the differential valve block is the main cause of the failure. After replacing the differential valve block, the fault was eliminated, and the traveling system of the whole machine returned to normal.
Numerical Simulation of Low Frequency Oscillation in an Aeroacoustic Wind Tunnel
Authors: Ma Ruixuan , Li Hu , Han Shuaibin , Wu Conghai , Zhang Shuhai , Wang Xunnian
Published: August 2022

The low frequency pressure oscillation in an aeroacoustic wind-tunnel seriously affects the flow quality and acoustic measurement. At present, there are many measures to suppress pressure oscillation, but due to the lack of in-depth understanding of its generation mechanism, these methods are not of general significance. In this paper, based on the open-source software OpenFOAM, the SA-DDES method is used for the unsteady computations for the two-dimensional simplified wind-tunnel model. The steady and unsteady fields inside and outside the jet flow are showed. The computational results show that the nonlinear interaction between the large scale vortices rolled up by the instabilities of the shear layer and the front wall of the collector of the wind-tunnel is the main reason responsible for the low frequency oscillation in an aeroacoustic wind-tunnel. In addition, it is concluded that in the feedback loop path of the excitation-feedback effect, the pressure waves produced by the large scale vortex structures inside the shear layer impinging on the front wall of the collector are reflected by the rear wall of the plenum chamber. The end of the path that the pressure waves travel upstream is where vortex shedding happens, not the nozzle exit.
Numerical Simulation Research on the Effect of the Rotor Passage Cross-Sectional Dimension on the Performance of Gas Wave Ejector
Authors: Zhao Yiming , Feng Qing , Hu Dapeng
Published: August 2022

The gas wave ejector (GWE) that utilizes pressure waves to realize the efficient energy transfer between gases has broad application prospects in chemical industry. In this study, the numerical simulation method was used to investigate the influence mechanism and law of the rotor passage height (h), width (w) and aspect ratio (h/w) on the equipment performance. The main conclusions are as follows: Increasing the passage height or width alone within a certain range may help improve the equipment performance, but if the passage width is too large, the sealing time of passage may be too short and the gas expansion may be incomplete, resulting in a significant reduction in performance. When the passage aspect ratio is fixed, the effects of passage width and height on the equipment performance are independent of one another, and the performance is determined by the superposition effect of these two. Within the range of passage cross-sectional area (40mm2~360mm2) investigated in this study, the passage aspect ratio for achieving the best performance is in the range of 0.71~1.6, and the efficiency and ejection rate under the same h/w increase with the increment of the cross-sectional area when h/w≥0.71.
Hydrogen-Oxygen Balance Method is used to Measure Hydrogen Consumption in Fuel Cell Vehicles
Authors: Guo Ting , Li Jun , Wu Shiyu , Wang Fang , Liang Rongliang
Published: August 2022

At present, there are four test methods to measure hydrogen consumption of fuel cell vehicles, namely weight method, pressure method, flow method and current method. During the test process, hydrogen supply outside the vehicle is required, which requires high requirements for operation and testing equipment. This paper presents a method to measure the hydrogen and oxygen concentrations in the tail gas of fuel cell vehicles without changing the vehicle structure, and uses the mass conservation method to evaluate hydrogen consumption. This paper compares and analyzes the data of traditional hydrogen consumption measurement method, introduces the principle and testing method of the new method, and the test results show that the hydrogen and oxygen balance method can accurately evaluate the hydrogen consumption of fuel cell vehicles.
Research on Thermal Balance Test and Evaluation Technology of Fuel Cell Vehicle
Authors: Guo Ting , Jin Xueyan , Liang Rongliang , Wu Shiyu , Nie Zhenyu , Wang Zhijun , Wang Guozhuo , Wang Fang
Published: August 2022

Thermal management system is importance to the efficiency and durability of fuel cell vehicles, so related researches are carried out on the thermal balance test and evaluation of fuel cells. Through theoretical and technical analysis, a test and evaluation method of thermal management system applied to various extreme conditions is proposed, and the test and evaluation conditions and evaluation indicators of each system of fuel cell vehicles are formed. In this paper, the thermal balance test results of a fuel cell vehicle are analyzed. The research results show that the thermal balance of fuel cell vehicles under extreme conditions reduces power and increases temperature difference to dissipate heat
Study of NH3-SCR Catalyst Combinations Based on Diesel Engine Exhaust Emission Mechanisms
Authors: Wang Xinyang , Yan Yan , Zhang Cheng
Published: August 2022

The overlap between the activity interval of a single catalyst and the exhaust gas temperature interval of several engines is small. In the industry, this problem is solved by increasing catalyst loadings. This has led to a certain amount of raw materials waste and increased catalyst production costs. In this study, Ce-W/Ti was introduced into Cu-SSZ-13 using solid phase grinding to change its activity range. Catalysts with different grinding ratios were subjected to small-sample performance experiments and characterization, and matching samples were selected by combining the results of the experiments with the emission characteristics of the MC07H diesel engine. World harmonized transient cycle (WHTC) and World harmonized steady-state cycle (WHSC) tests were conducted on the engine bench to investigate the causes of NO
x
concentration maxima during diesel engine operation using this catalyst combination strategy. The WHTC and WHSC emissions are 0.2464 and 0.1987 g/kWh. Based on the combined strategy, a performance match with diesel engines can be achieved while reducing the cost by $11/kg compared with the Cu-SSZ-13 catalyst, demonstrating the potential of the process for large-scale applications.
Effect of Alkaline Earth Metals Doping on the Electronic Structure, Magnetic and Optical Properties of g-SiC Monolayer System by First Principles Calculation
Authors: Ma Deming , Wei Hongbin , Shen Yang , Cui Zhen , Li Enling , Zhang Lin
Published: August 2022

The band structure, electronic, magnetic, and optical properties of g-SiC monolayers doped with alkaline earth metals (Be, Mg, Ca, Sr, and Ba) are calculated by means of first principles based on density functional theory. Although the intrinsic g-SiC monolayer is nonmagnetic, it shows magnetic properties after doping with alkaline earth metals. The magnetic moments are, in the order of the above-named dopants, 1.583 μ
B, 1817 μ
B, 2.000 μ
B, 2.000 μ
B, and 2.000 μ
B. Charge transfer and the net spin charge occur mainly between the dopant atom and surrounding C atoms. The results show that the conductivity of g-SiC can be greatly improved by doping with alkaline earth metals, a technique that can be applied to the field of semiconductor spintronics. High absorption peaks in the ultraviolet indicate that the material has potential applications in UV optoelectronic devices.
Earthquake Escape Simulator: A System for Disaster Knowledge Popularization
Authors: Li Liuxian , Fang Zhiyang
Published: August 2022

China is a country prone to geological hazards, and it has become especially urgent to improve citizens’ awareness of earthquake safety prevention and escape ability in the effort to protect ourselves from disaster. However, from the effect of the current popular science education, there is still a significant lack of awareness and skills of the masses in emergency risk avoidance and self-rescue. Based on Unity3D game engine, we developed an EES (Earthquake Escape Simulator) disaster knowledge popular science system, a training platform for primary and secondary school students emergency evacuation and escape drills. The system is interspersed with the emergency and medical knowledge of self-rescue and rescue of others, so the earthquake disaster knowledge is imperceptibly popularized to the players in a situational way.
Topology Control of WSNs Based on Persistent Homology
Authors: Yu Jintao , Lu Xiaowei , Gao Zhenhua , Li Shizhou , Li Lei , Li Congcong , Tong He
Published: August 2022

WSNs can easily lead to the failure or even collapse of the whole network due to energy constraints. Therefore, in order to reduce a series of losses caused by energy consumption, it is necessary to take corresponding topology control to improve the overall performance of the network and make WSNs more secure and reliable. In the research of WSNs, one of the most important technical ways to improve the overall performance of the network is to optimize the topology of the network. In this paper, a topology control method of wireless sensor network based on continuous coherence is proposed. Under the condition of ensuring that the network topology remains unchanged, the energy loss in the network is reduced by sleeping the redundant nodes in the network, so as to improve the network efficiency. The experimental results confirm the effectiveness of the method.
Water Allocation Model Based on Improved TOPSIS Method
Authors: Feng Dingrong , Chen Zheng , Yang Yanxiong , Qiu Ruofeng , Qi Yunfei , Liu Tao
Published: August 2022

In this paper, in order to improve traditional TOPSIS water weight distribution model, the analytic hierarchy process combined with coefficient of variation method is used to calculate the weight. In the improved model, vertical distance is adopted to calculate the result, which avoids some defects caused by Euclidean distance. In the process of practical application, improved TOPSIS method selected 12 evaluation indicators with water resources development, social benefits, economic benefits, ecological environmental benefits and other aspects of evaluation, making the model more fit the reality. The results show that when the method is applied to water right allocation in Arizona, the calculated results are in agreement with the practice.
FAIAD: Feature Adaptive-based Image Anomaly Detection
Authors: Zhang Qianqian , Wei Hongyang , Du Xusheng , Li Xue , Yu Jiong
Published: August 2022

Image abnormality detection is a hot research topic in the field of data mining, and it has great application value in the fields of industrial appearance defect detection and medical image analysis. To address the problem of poor performance of anomaly detection models caused by incomplete feature extraction, we propose a feature-adaptive image anomaly detection model. FAIAD first trains the initial feature extraction model by pre-training the model. Then introduce feature adaptation methods to improve image feature extraction performance. The last step is to calculate the accuracy of image anomaly detection. In order to explore the feature extraction effects of different neural networks, this paper designs three kinds of backbone network comparison experiments. Experimenting on both Cifar-10 and Fashion-MNIST datasets, the accuracy of our model improved by 3.5% and 2.3%, respectively, compared to the baseline model. The experimental results show that combining pre-trained models with feature adaptation methods can effectively improve the performance of anomaly detection models.
Research on Improved Random Forest Algorithm for Highly Unbalanced Data
Authors: Sun Jianming , Shen Zicheng
Published: August 2022

To address the problems of low prediction performance of minority class samples due to highly unbalanced data and improved prediction performance of minority class but decreased prediction performance of majority class after balanced training set, an improved algorithm combining feature fusion and random forests quantile classifier is proposed. The algorithm obtains multiple data subsets by feature segmentation through sliding windows, and then inputs the obtained data subsets into the quantile random forest for cross-validation to obtain multiple class probability vectors for each sample, and finally splices the obtained class probability vectors with the original data set as new features to form a new data set, and uses the new combination of features to better represent the relationship between minority and majority classes, thus improve the overall classification performance of the classifier. Experiments on the KEEL dataset show that the improved algorithm improves the overall sample classification performance for unbalanced data compared to other algorithms.