Triclosan(TCS) poses harmful risks to ecosystems and human health owing to its endocrine-disrupting effects.Therefore,developing an efficient and sustainable technology to degrade TCS is urgently needed.Herein,cobalt ...Triclosan(TCS) poses harmful risks to ecosystems and human health owing to its endocrine-disrupting effects.Therefore,developing an efficient and sustainable technology to degrade TCS is urgently needed.Herein,cobalt oxyhydroxide @covalent organic frameworks(CoOOH@COFs) S-scheme heterojunction was synthesized,which combined the visible-light-driven photocatalysis and peroxymonosulfate(PMS) activation to synergistically generate abundant reactive oxygen species(ROSs) for TCS degradation.The degradation efficiency of TCS reached 100 % within 8 min in the Vis-CoOOH@COFs/PMS system,and the reaction rate constant was 0.456 min^(-1),which was nearly 1.90 and 2.85 times that of single Co OOH and COFs,and2.36 times that under dark condition,respectively.The density functional theory(DFT) calculations confirmed the energy band bending of CoOOH@COFs and S-scheme charge transport from COFs to Co OOH.Both experimental and theoretical analyses indicated that Co OOH@COFs in photocatalytic-PMS activation systems synergistically facilitated photo-generated carrier separation,enhanced interfacial electron transfer,accelerated PMS activation,and generated multiple ROSs.In particular,photogenerated electrons(e^(-))accelerated the Co(Ⅲ)/Co(Ⅱ) redox cycle,while the PMS captured the e-,which significantly decreased the charge combination of Co OOH@COFs.Radicals(O_(2)^(·-),^(·)OH,and SO_(4)^(·-)) and non-radicals(such as ^(1)O_(2),h^(+),and e^(-)) were both presented in the Vis-CoOOH@COFs/PMS system,with O_(2)^(-) playing a dominant role in TCS degradation.Furthermore,the pathway of TCS degradation and toxicity of intermediates were explored by DFT calculation and transformation product identification.Importantly,the environmentally friendly CoOOH@COFs S-scheme heterojunction exhibited excellent stability and reusability.In conclusion,this study innovatively designed an S-scheme heterojunction in the photocatalytic-PMS activation system,providing guidance and theoretical support for efficient and eco-friendly wastewater treatment.展开更多
Mitochondria play a crucial role as organelles,managing several physiological processes such as redox balance,cell metabolism,and energy synthesis.Initially,the assumption was that mitochondria primarily resided in th...Mitochondria play a crucial role as organelles,managing several physiological processes such as redox balance,cell metabolism,and energy synthesis.Initially,the assumption was that mitochondria primarily resided in the host cells and could exclusively transmit from oocytes to offspring by a mechanism known as vertical inheritance of mitochondria.Recent scholarly works,however,suggest that certain cell types transmit their mitochondria to other developmental cell types via a mechanism referred to as intercellular or horizontal mitochondrial transfer.This review details the process of which mitochondria are transferred across cells and explains the impact of mitochondrial transfer between cells on the efficacy and functionality of cancer cells in various cancer forms.Specifically,we review the role of mitochondria transfer in regulating cellular metabolism restoration,excess reactive oxygen species(ROS)generation,proliferation,invasion,metastasis,mitophagy activation,mitochondrial DNA(mtDNA)inheritance,immune system modulation and therapeutic resistance in cancer.Additionally,we highlight the possibility of using intercellular mitochondria transfer as a therapeutic approach to treat cancer and enhance the efficacy of cancer treatments.展开更多
Accurate satellite data assimilation under all-sky conditions requires enhanced parameterization of scattering properties for frozen hydrometeors in clouds.This study aims to develop a nonspherical scattering look-up ...Accurate satellite data assimilation under all-sky conditions requires enhanced parameterization of scattering properties for frozen hydrometeors in clouds.This study aims to develop a nonspherical scattering look-up table that contains the optical properties of five hydrometeor types—rain,cloud water,cloud ice,graupel,and snow—for the Advanced Radiative Transfer Modeling System(ARMS)at frequencies below 220 GHz.The discrete dipole approximation(DDA)method is employed to compute the single-scattering properties of solid cloud particles,modeling these particles as aggregated roughened bullet rosettes.The bulk optical properties of the cloud layer are derived by integrating the singlescattering properties with a modified Gamma size distribution,specifically for distributions with 18 effective radii.The bulk phase function is then projected onto a series of generalized spherical functions,applying the delta-M method for truncation.The results indicate that simulations using the newly developed nonspherical scattering look-up table exhibit significant consistency with observations under deep convection conditions.In contrast,assuming spherical solid cloud particles leads to excessive scattering at mid-frequency channels and insufficient scattering at high-frequency channels.This improvement in radiative transfer simulation accuracy for cloudy conditions will better support the assimilation of allsky microwave observations into numerical weather prediction models.·Frozen cloud particles were modeled as aggregates of bullet rosettes and the optical properties at microwave range were computed by DDA.·A complete process and technical details for constructing a look-up table of ARMS are provided.·The ARMS simulations generally show agreement with observations of MWTS and MWHS under typhoon conditions using the new look-up table.展开更多
The classical-quantum analogue offers a new platform for exploring extreme dynamic control of mechanical systems.In this work,the concept of the stimulated adiabatic passage of quantum states is extended to mechanical...The classical-quantum analogue offers a new platform for exploring extreme dynamic control of mechanical systems.In this work,the concept of the stimulated adiabatic passage of quantum states is extended to mechanical systems for achieving unidirectional energy transportation.The mechanical analog of stimulated adiabatic passage is realized in three mechanical resonators coupled with the time-varying stiffness,which are delicately modulated to mimic the selective population of quantum states.Based on the tight-binding approximation,an analytical model for the classical-quantum analogue of the adiabatic passage effect is established to realize the one-way energy transfer control.Numerical results demonstrate that the vibration energy acquired from an initially excited resonator can be transferred to the target one via an intermediate resonator,while flow in the reverse direction is prohibited due to energy localization in the intermediate resonator.The model holds application potentials in energy suppression and harvesting,and offers promising prospects for unidirectional wave and vibration control.展开更多
Fluorescent probes based on intramolecular charge transfer(ICT) have obvious advantages for accurate quantitative analysis.To obtain high-performance ratiometric probes requires distinct photophysical properties durin...Fluorescent probes based on intramolecular charge transfer(ICT) have obvious advantages for accurate quantitative analysis.To obtain high-performance ratiometric probes requires distinct photophysical properties during recognition reaction process,which is closely related to their ICT characteristics.1,8-Naphthalimide is known as a typical fluorophore with desirable ICT property when functionalized with an electron-donating moiety at the para-position of the naphthalene chromophore.Although the photophysical properties of para-substituted 1,8-naphthalimide have been well studied,its meta-substituted counterpart has not been fully evaluated since the meta-position is conventionally thought to be weakly conjugated.Herein,combined experimental and theoretical studies are performed which consistently indicate that stronger charge transfer(CT) is exhibited by the meta-amino substituted 1,8-naphthalimide(m-NH_(2)) compared to the para-amino substituted one(p-NH_(2)).The ratiometric response of fluorescence with significant changes in wavelength and intensity upon acetylation(m-NAc and p-NAc) can be attributed to the larger ICT and stronger-NH_(2) vibrations.This observation is further demonstrated by deuterium oxide experiments,viscosity experiments and quantum chemical calculations.The practical application of meta-amino-1,8-naphthalimide ICT-based probes is also confirmed.This research is expected to bring an in-depth understanding of π-conjugated systems with ICT characteristics,and facilitates the design of sensitive ICT fluorescent probes with meta-amino substitution.展开更多
Current research on rail vehicle system vibrations primarily relies on numerical methods,with vibration transfer functions commonly derived through data fitting.However,the physical mechanisms underlying these vibrati...Current research on rail vehicle system vibrations primarily relies on numerical methods,with vibration transfer functions commonly derived through data fitting.However,the physical mechanisms underlying these vibrations are not well understood.To clarify the vibration transfer function and its characteristics,four basic input vectors are defined,and an analytical method is proposed.The vibration transfer functions of the vehicle system are solved,and their spatial coherence is analyzed.The results show that there are two spatial scales and four coherent modes in the vehicle system.The track irregularity wavelengths are combined with two spatial scales to alter the proportions of basic input vectors and then show the characteristics of spatial coherence.Four coherent modes are involved in wheel-rail force and primary suspension force;two coherent modes are involved in bogie vertical motion;and their dominant modes vary with the input frequency.On the other hand,the coherent modes involved in the bogie pitching motion and vehicle body motion are single and fixed over the whole range of frequency.This study presents an analytical method for the rapid solution of dynamic responses in vehicle systems and systematically analyzes the coherence behavior of vibration transfer functions with respect to tracking irregularity wavelengths.展开更多
The latent heat thermal energy storage system with solid-liquid phase-change material(SLPCM-LHTES)as energy storage medium provides outstanding advantages such as system simplicity,stable temperature control,and high ...The latent heat thermal energy storage system with solid-liquid phase-change material(SLPCM-LHTES)as energy storage medium provides outstanding advantages such as system simplicity,stable temperature control,and high energy storage density,showing great potential toward addressing the energy storage problems associated with decentralized,intermittent,and unstable renewable energy sources.Notably,effective heat transfer within the SLPCM-LHTES is crucial for extending its application potential.Therefore,a comprehensive understanding of the heat transfer processes in SLPCM-LHTES from a theoretical perspective is necessary.In this review,we propose a three-stage heat transfer pathway in SLPCM-LHTES,including external heating,interfacial heat transfer,and intrinsic phase transition processes.From the perspective of this three-stage pathway,the theoretical basis of heat transfer processes and typical efficiency enhancement strategies in SLPCM-LHTES are summarized.Moreover,an overview of the typical applications of SLPCM-LHTES in various fields,such as building energy efficiency,textiles and garments,and battery thermal management,is presented.Finally,the remaining challenges and possible avenues of research in this burgeoning field will also be discussed.展开更多
The excited state dynamics and critically regulated factors of reverse intersystem crossing(RISC)in through-space charge transfer(TSCT)molecules have received insufficient attention.Here,five molecules of through spac...The excited state dynamics and critically regulated factors of reverse intersystem crossing(RISC)in through-space charge transfer(TSCT)molecules have received insufficient attention.Here,five molecules of through space/bond charge transfer inducing thermally activated delayed fluorescence(TADF)are prepared,and their excited state charge transfer processes are studied by ultrafast transient absorption and theoretical calculations.DM-Z has a largerΔEST,leading to a longer lifetime of intersystem crossing(ISC),resulting in the lowest photoluminescence quantum yield(PLQY).Oppositely,ISC and RISC are demonstrated to take place with shorter lifetimes for TSCT molecules.The face-to-faceπ-πstacking interactions and electron communication enable DM-B and DM-BX to have an efficient RISC,increasing the weight coefficient of RISC from 1.7%(DM-X)to close to 50%(DM-B and DM-BX)in the solvents,which make DM-BX and DM-B to have a high PLQY.However,partial local excitation in the donor center is observed and the charge transfer is decreased for DM-G and DM-X.The triplet excited state(DM-G)or singlet excited state(DM-X)mainly undergoes inactivation through a non-radiative relaxation process,resulting in less RISC and low PLQY.This work provides theoretical hints to enhance the RISC process in the TADF materials.展开更多
Achieving artificial simulations of multi-step energy transfer processes and conversions in nature remains a challenge.In this study,we present a three-step sequential energy transfer process,which was constructed thr...Achieving artificial simulations of multi-step energy transfer processes and conversions in nature remains a challenge.In this study,we present a three-step sequential energy transfer process,which was constructed through host-vip interactions between a piperazine derivative(PPE-BPI)with aggregationinduced emission(AIE)and cucurbit[7]uril(CB[7])in water to serve as ideal energy donors.To achieve multi-step sequential energy transfer,we employ three distinct fluorescent dyes Eosin B(EsB),Sulforhodamine 101(SR101),and Cyanine 5(Cy5)as energy acceptors.The PPE-PBI-2CB[7]+EsB+SR101+Cy5 system demonstrates a highly efficient three-step sequential energy transfer mechanism,starting with PPEPBI-2CB[7]and transferring energy successively to EsB,SR101,and finally to Cy5,with remarkable energy transfer efficiencies.More interestingly,with the progressive transfer of energy in the multi-step energy transfer system,the generation efficiency of superoxide anion radical(O_(2)•-)increased gradually,which can be used as photocatalysts for selectively photooxidation of N-phenyltetrahydroisoquinoline in an aqueous medium with a high yield of 86%after irradiation for 18 h.This study offers a valuable investigation into the simulation of multi-step energy transfer processes and transformations in the natural world,paving the way for further research in the field.展开更多
The present study was conducted to examine the trophic transfer of potentially toxic elements(PTEs)in a closed arsenic mine.Eight PTEs in a soil-plant-leaf litter-earthworm-top predators(free-range local chicken and w...The present study was conducted to examine the trophic transfer of potentially toxic elements(PTEs)in a closed arsenic mine.Eight PTEs in a soil-plant-leaf litter-earthworm-top predators(free-range local chicken and wild passerine bird)system were analyzed for nitrogen and carbon stable isotopes,PTE concentrations,bioaccumulation factors(BAFs),and transfer factors(TFs).The PTE concentrations in soils from mining areas were generally higher than a adjacent controlled area,with As and Cd in soils showing the prominent compared to other six PTEs,as seen for the indices of geo-accumulation index(I_(geo)),pollution index(PI)and potential ecological risk index(RI).The relatively high BAF and TF values suggested a distinct biotransfer of PTEs along the soil-plant-leaf litter-earthworm system.BAFs were mostly<1 except in earthworms,indicating that earthworms had a strong capacity to take up these metals.The TFs varied both among PTEs and organism’s species,e.g.,the transfer capacities of As in Pteris vittata and Pteris cretica,Cd in Miscanthus sinensis,and Pb,Cr and Mn in moss were the highest.For local free-range chicken and wild passerine bird,the concentrations of PTEs were higher in gastric contents and feather than in internal tissue(stomach,liver and heart),with lower contents in muscle and egg.Bioaccumulation of PTEs generally decreased from decomposer earthworms,to primary producer plants,to top predator,indicating a potential bio-dilution tendency in higher trophic levels in the terrestrial food chain.展开更多
This study presents an emergency control method for sub-synchronous oscillations in wind power gridconnected systems based on transfer learning,addressing the issue of insufficient generalization ability of traditiona...This study presents an emergency control method for sub-synchronous oscillations in wind power gridconnected systems based on transfer learning,addressing the issue of insufficient generalization ability of traditional methods in complex real-world scenarios.By combining deep reinforcement learning with a transfer learning framework,cross-scenario knowledge transfer is achieved,significantly enhancing the adaptability of the control strategy.First,a sub-synchronous oscillation emergency control model for the wind power grid integration system is constructed under fixed scenarios based on deep reinforcement learning.A reward evaluation system based on the active power oscillation pattern of the system is proposed,introducing penalty functions for the number of machine-shedding rounds and the number of machines shed.This avoids the economic losses and grid security risks caused by the excessive one-time shedding of wind turbines.Furthermore,transfer learning is introduced into model training to enhance the model’s generalization capability in dealing with complex scenarios of actual wind power grid integration systems.By introducing the Maximum Mean Discrepancy(MMD)algorithm to calculate the distribution differences between source data and target data,the online decision-making reliability of the emergency control model is improved.Finally,the effectiveness of the proposed emergency control method for multi-scenario sub-synchronous oscillation in wind power grid integration systems based on transfer learning is analyzed using the New England 39-bus system.展开更多
Sensitization of metal-centered forbidden transitions is of great significance.Solid MnII-based phosphors with d-d forbidden transition sensitized by CeIIIwith d-f allowed transition are promising light conversion mat...Sensitization of metal-centered forbidden transitions is of great significance.Solid MnII-based phosphors with d-d forbidden transition sensitized by CeIIIwith d-f allowed transition are promising light conversion materials,but the energy transfer mechanism in CeIII-MnIIis still in dispute for the uncertainty of distances between metal centers.Herein,for the first time,we explored the energy transfer mechanism in two well-designed luminescent heteronuclear complexes with clear crystal structures,i.e.,Ce-N8-Mn and Ce-N2O6-Mn(N8=1,4,7,10,13,16,21,24-octaazabicyclo[8.8.8]hexacosane;N2O6=4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo[8.8.8]hexacosane).Short distances between metal centers facilitate efficient energy transfer from CeIIIto MnIIin both complexes,resulting in high photoluminescence quantum yield up to unity.After systematic study of the two heteronuclear complexes as well as two reference complexes Ce(N8)Br3and Ce(N2O6)Br3,we concluded that dipole-quadrupole interaction is the dominant energy transfer mechanism in the heteronuclear complexes.展开更多
The ammunition loading system manipulator is susceptible to gear failure due to high-frequency,heavyload reciprocating motions and the absence of protective gear components.After a fault occurs,the distribution of fau...The ammunition loading system manipulator is susceptible to gear failure due to high-frequency,heavyload reciprocating motions and the absence of protective gear components.After a fault occurs,the distribution of fault characteristics under different loads is markedly inconsistent,and data is hard to label,which makes it difficult for the traditional diagnosis method based on single-condition training to generalize to different conditions.To address these issues,the paper proposes a novel transfer discriminant neural network(TDNN)for gear fault diagnosis.Specifically,an optimized joint distribution adaptive mechanism(OJDA)is designed to solve the distribution alignment problem between two domains.To improve the classification effect within the domain and the feature recognition capability for a few labeled data,metric learning is introduced to distinguish features from different fault categories.In addition,TDNN adopts a new pseudo-label training strategy to achieve label replacement by comparing the maximum probability of the pseudo-label with the test result.The proposed TDNN is verified in the experimental data set of the artillery manipulator device,and the diagnosis can achieve 99.5%,significantly outperforming other traditional adaptation methods.展开更多
Industry and energy continue to require piston engines(PICE)at a high level worldwide.Therefore,science and technology must urgently work on improving the PICE working cycle.Improving the quality of the intake process...Industry and energy continue to require piston engines(PICE)at a high level worldwide.Therefore,science and technology must urgently work on improving the PICE working cycle.Improving the quality of the intake process of theworking fluid into the cylinder is one of the most effective ways to improve the operational performance of PICE.The purpose of the study was to assess the impact of various cylinder head(CylH)designs on the gas-dynamic and heat-exchange qualities of air flows within an engine model’s intake system.Three different CylH designs were studied:the basic configuration and upgraded cylinder heads with a square valve and a square valve port.These designs are innovative.Laboratory conditions were used to conduct the studies for stationary air flow.The experiments covered the range of Reynolds numbers from 8500 to 96,000.The intake system’s gas dynamics and heat transfer were determined using the thermal anemometry method,which was based on constant-temperature hot-wire anemometers.It has been established that the use of upgraded CylHs causes an increase in the turbulence number of flow by an average of 13.5%.Additionally,itwas found that the increase in the turbulence number of flowin the cylinder is about 19%when installing new CylH designs.It was shown that therewas an increase in the heat transfer coefficient in the intake pipe by 10%–40%when installing modernized CylH designs in the intake system.The article focused on the problems of increasing the turbulence level and intensifying the heat transfer of stationary air flow in the intake system,specifically in PICEs.The study’s findings are novel in the areas of applied gas dynamics and PICEs.展开更多
This study introduces a Transformer-based multimodal fusion framework for simulating multiphase flow and heat transfer in carbon dioxide(CO_(2))–water enhanced geothermal systems(EGS).The model integrates geological ...This study introduces a Transformer-based multimodal fusion framework for simulating multiphase flow and heat transfer in carbon dioxide(CO_(2))–water enhanced geothermal systems(EGS).The model integrates geological parameters,thermal gradients,and control schedules to enable fast and accurate prediction of complex reservoir dynamics.The main contributions are:(i)development of a workflow that couples physics-based reservoir simulation with a Transformer neural network architecture,(ii)design of physics-guided loss functions to enforce conservation of mass and energy,(iii)application of the surrogate model to closed-loop optimization using a differential evolution(DE)algorithm,and(iv)incorporation of economic performance metrics,such as net present value(NPV),into decision support.The proposed framework achieves root mean square error(RMSE)of 3–5%,mean absolute error(MAE)below 4%,and coefficients of determination greater than 0.95 across multiple prediction targets,including production rates,pressure distributions,and temperature fields.When compared with recurrent neural network(RNN)baselines such as gated recurrent units(GRU)and long short-term memory networks(LSTM),as well as a physics-informed reduced-order model,the Transformer-based approach demonstrates superior accuracy and computational efficiency.Optimization experiments further show a 15–20%improvement in NPV,highlighting the framework’s potential for real-time forecasting,optimization,and decision-making in geothermal reservoir engineering.展开更多
In indoor environments,various batterypowered Internet of Things(IoT)devices,such as remote controllers and electronic tags on high-level shelves,require efficient energy management.However,manually monitoring remaini...In indoor environments,various batterypowered Internet of Things(IoT)devices,such as remote controllers and electronic tags on high-level shelves,require efficient energy management.However,manually monitoring remaining energy levels and battery replacement is both inadequate and costly.This paper introduces an energy management system for indoor IoT,which includes a mobile energy station(ES)for enabling on-demand wireless energy transfer(WET)in radio frequency(RF),some energy receivers(ERs),and a cloud server.By implementing a two-stage positioning system and embedding energy receivers into traditional IoT devices,we robustly manage their energy storage.The experimental results demonstrate that the energy receiver can harvest a minimum power of 58 mW.展开更多
Realizing efficient and controlled state transfers is necessary for implementing a wide range of classical and quantum information protocols.Recent studies have demonstrated that both asymmetric and symmetric state tr...Realizing efficient and controlled state transfers is necessary for implementing a wide range of classical and quantum information protocols.Recent studies have demonstrated that both asymmetric and symmetric state transfers can be achieved by encircling an exceptional point(EP)in non-Hermitian(NH)systems.However,the application of this phenomenon has been restricted to scenarios where an EP exists in single-qubit systems and is associated with a specific type of dissipation.In this work,we demonstrate efficient and controlled symmetric and asymmetric Bell-state transfers by modulating system parameters within a Jaynes-Cummings model while accounting for atomic spontaneous emission and cavity decay.The effective suppression of nonadiabatic transitions enables a symmetric exchange of Bell states irrespective of the encircling direction.Furthermore,we report a counterintuitive finding:the presence of an EP is not indispensable for implementing asymmetric state transfers in NH systems.We achieve perfect asymmetric Bell-state transfers even in the absence of an EP by dynamically orbiting around an approximate EP.Our work presents an approach to effectively and reliably manipulate entangled states with both symmetric and asymmetric characteristics,through dissipation engineering in NH systems.展开更多
This study investigates the enhancement of convective heat transfer in a serpentine pipe using ferrofluid flow influenced by dual non-uniform magnetic sources.The primary objective is to improve thermal performance in...This study investigates the enhancement of convective heat transfer in a serpentine pipe using ferrofluid flow influenced by dual non-uniform magnetic sources.The primary objective is to improve thermal performance in compact cooling systems,such as those used in heat exchangers.A two-dimensional,steady-state Computational Fluid Dynamic(CFD)model is developed in ANSYS Fluent to simulate the behavior of an incompressible ferrofluid under applied constant heat flux and magnetic fields.The magnetic force is modeled using the Kelvin force,which acts on magnetized nanoparticles in response to spatially varying electromagnetic fields generated by two strategically positioned current-carrying wires.The effects of magnetic field strength,quantified by the magnetic number(Mn),on flow behavior and temperature distribution are thoroughly analyzed.The results indicate that increasing Mn leads to higher Nusselt numbers,demonstrating enhanced convective heat transfer.Secondary vortices induced by magnetic forcing improve fluid mixing,particularly in curved regions of the pipe.A mesh-independence study and model validation with benchmark data support the reliability of the numerical framework.This work highlights the potential of magnetic-field-assisted thermal control in energy-efficient cooling applications and provides a foundation for the further development of advanced ferrofluid-based heat transfer systems.展开更多
Accurate assessment of seismic landslide susceptibility is crucial for disaster prevention and emergency decision-making.Although machine learning methods have been widely applied in this field,they exhibit a strong d...Accurate assessment of seismic landslide susceptibility is crucial for disaster prevention and emergency decision-making.Although machine learning methods have been widely applied in this field,they exhibit a strong dependence on large quantities of highquality samples,resulting in significantly low prediction accuracy of existing studies under data-scarce or crossregional prediction scenarios,which fail to meet practical application requirements.To address this issue,this study proposes an intelligent prediction model integrating transfer learning and a sampling optimization strategy,aiming to enhance the accuracy and applicability of seismic landslide susceptibility assessment.The model first improves the sample collection method through the sampling optimization strategy to enhance the precision and representativeness of training samples.This not only ensures the accuracy of origin area training but also further strengthens the model's predictive ability in the target area.Subsequently,it incorporates Transfer Component Analysis(TCA)to overcome the differences in environmental characteristics between the origin area and target area,and couples TCA with the Light GBM algorithm to construct the TCA-Light GBM model,realizing the assessment of seismic landslide susceptibility in sample-free areas.Validated through case studies of the Jiuzhaigou and Luding earthquakes,the results demonstrate that the proposed TCALight GBM transfer learning method exhibits excellent applicability in seismic landslide susceptibility prediction.After optimization with the TCA algorithm,the model's prediction performance in the target domain is significantly improved,with the AUC value increasing from 0.719 to 0.827,representing an increase of approximately 15.02%.This indicates that TCA technology can effectively alleviate the feature distribution discrepancy between the source domain and target domain,enhancing the model's generalization ability.The method is particularly suitable for scenarios with data scarcity and cross-regional prediction and can provide reliable technical support for the emergency response and risk prevention and control of seismic hazards.展开更多
The development of catalytic multicomponent reactions for constructing complex organic scaffolds from readily accessible commodity chemicals is a key pursuit in contemporary synthetic chemistry.Current methods for syn...The development of catalytic multicomponent reactions for constructing complex organic scaffolds from readily accessible commodity chemicals is a key pursuit in contemporary synthetic chemistry.Current methods for synthesizing thioesters primarily rely on the acylation of thiols,which produces substantial waste and requires malodorous,unstable sulfur sources.In this work,we introduce a photocatalyzed hydrogen transfer strategy that enables a three-component synthesis of thioesters using abundant primary alcohols,easily available alkenes and elemental sulfur under mild conditions.This protocol demonstrates broad applicability and high chemo-and regioselectivity for both primary alcohols and alkenes,highlighting the advantage and potential of photo-mediated hydrogen transfer in facilitating multicomponent reactions using primary alcohol and elemental sulfur feedstocks.展开更多
文摘Triclosan(TCS) poses harmful risks to ecosystems and human health owing to its endocrine-disrupting effects.Therefore,developing an efficient and sustainable technology to degrade TCS is urgently needed.Herein,cobalt oxyhydroxide @covalent organic frameworks(CoOOH@COFs) S-scheme heterojunction was synthesized,which combined the visible-light-driven photocatalysis and peroxymonosulfate(PMS) activation to synergistically generate abundant reactive oxygen species(ROSs) for TCS degradation.The degradation efficiency of TCS reached 100 % within 8 min in the Vis-CoOOH@COFs/PMS system,and the reaction rate constant was 0.456 min^(-1),which was nearly 1.90 and 2.85 times that of single Co OOH and COFs,and2.36 times that under dark condition,respectively.The density functional theory(DFT) calculations confirmed the energy band bending of CoOOH@COFs and S-scheme charge transport from COFs to Co OOH.Both experimental and theoretical analyses indicated that Co OOH@COFs in photocatalytic-PMS activation systems synergistically facilitated photo-generated carrier separation,enhanced interfacial electron transfer,accelerated PMS activation,and generated multiple ROSs.In particular,photogenerated electrons(e^(-))accelerated the Co(Ⅲ)/Co(Ⅱ) redox cycle,while the PMS captured the e-,which significantly decreased the charge combination of Co OOH@COFs.Radicals(O_(2)^(·-),^(·)OH,and SO_(4)^(·-)) and non-radicals(such as ^(1)O_(2),h^(+),and e^(-)) were both presented in the Vis-CoOOH@COFs/PMS system,with O_(2)^(-) playing a dominant role in TCS degradation.Furthermore,the pathway of TCS degradation and toxicity of intermediates were explored by DFT calculation and transformation product identification.Importantly,the environmentally friendly CoOOH@COFs S-scheme heterojunction exhibited excellent stability and reusability.In conclusion,this study innovatively designed an S-scheme heterojunction in the photocatalytic-PMS activation system,providing guidance and theoretical support for efficient and eco-friendly wastewater treatment.
基金supported by the National Natural Science Foundation of China(Grant No.:82272749)the Natural Science Foundation of Liaoning Province,China(Grant No.:2022-MS-190).
文摘Mitochondria play a crucial role as organelles,managing several physiological processes such as redox balance,cell metabolism,and energy synthesis.Initially,the assumption was that mitochondria primarily resided in the host cells and could exclusively transmit from oocytes to offspring by a mechanism known as vertical inheritance of mitochondria.Recent scholarly works,however,suggest that certain cell types transmit their mitochondria to other developmental cell types via a mechanism referred to as intercellular or horizontal mitochondrial transfer.This review details the process of which mitochondria are transferred across cells and explains the impact of mitochondrial transfer between cells on the efficacy and functionality of cancer cells in various cancer forms.Specifically,we review the role of mitochondria transfer in regulating cellular metabolism restoration,excess reactive oxygen species(ROS)generation,proliferation,invasion,metastasis,mitophagy activation,mitochondrial DNA(mtDNA)inheritance,immune system modulation and therapeutic resistance in cancer.Additionally,we highlight the possibility of using intercellular mitochondria transfer as a therapeutic approach to treat cancer and enhance the efficacy of cancer treatments.
基金supported by the National Key Research and Development Program of China(Grant No.2021YFB3900400)the National Natural Science Foundation of China(Grant Nos.U2142212 and 42361074)。
文摘Accurate satellite data assimilation under all-sky conditions requires enhanced parameterization of scattering properties for frozen hydrometeors in clouds.This study aims to develop a nonspherical scattering look-up table that contains the optical properties of five hydrometeor types—rain,cloud water,cloud ice,graupel,and snow—for the Advanced Radiative Transfer Modeling System(ARMS)at frequencies below 220 GHz.The discrete dipole approximation(DDA)method is employed to compute the single-scattering properties of solid cloud particles,modeling these particles as aggregated roughened bullet rosettes.The bulk optical properties of the cloud layer are derived by integrating the singlescattering properties with a modified Gamma size distribution,specifically for distributions with 18 effective radii.The bulk phase function is then projected onto a series of generalized spherical functions,applying the delta-M method for truncation.The results indicate that simulations using the newly developed nonspherical scattering look-up table exhibit significant consistency with observations under deep convection conditions.In contrast,assuming spherical solid cloud particles leads to excessive scattering at mid-frequency channels and insufficient scattering at high-frequency channels.This improvement in radiative transfer simulation accuracy for cloudy conditions will better support the assimilation of allsky microwave observations into numerical weather prediction models.·Frozen cloud particles were modeled as aggregates of bullet rosettes and the optical properties at microwave range were computed by DDA.·A complete process and technical details for constructing a look-up table of ARMS are provided.·The ARMS simulations generally show agreement with observations of MWTS and MWHS under typhoon conditions using the new look-up table.
基金supported by the National Key R&D Program of China(2024YFB3408700 and 2024YFB3408702)the National Natural Science Foundation of China(Grant Numbers 12225203,12402100,11991030,11991033,11622215,and 11872111)the 111 project(Grant Number B16003).
文摘The classical-quantum analogue offers a new platform for exploring extreme dynamic control of mechanical systems.In this work,the concept of the stimulated adiabatic passage of quantum states is extended to mechanical systems for achieving unidirectional energy transportation.The mechanical analog of stimulated adiabatic passage is realized in three mechanical resonators coupled with the time-varying stiffness,which are delicately modulated to mimic the selective population of quantum states.Based on the tight-binding approximation,an analytical model for the classical-quantum analogue of the adiabatic passage effect is established to realize the one-way energy transfer control.Numerical results demonstrate that the vibration energy acquired from an initially excited resonator can be transferred to the target one via an intermediate resonator,while flow in the reverse direction is prohibited due to energy localization in the intermediate resonator.The model holds application potentials in energy suppression and harvesting,and offers promising prospects for unidirectional wave and vibration control.
基金financially supported by National Key Research and Development Programs (Nos.2022YFD1700403 and 2023YFD1700303)National Natural Science Foundation of China (Nos.12274128 and 12250003)+2 种基金Shanghai Rising-Star Program (No.21QA1402600)the support of NYU-ECNU Center for Computational Chemistry at NYU Shanghaithe University of Bath and the Open Research Fund of the School of Chemistry and Chemical Engineering,Henan Normal University (No.2020ZD01) for support。
文摘Fluorescent probes based on intramolecular charge transfer(ICT) have obvious advantages for accurate quantitative analysis.To obtain high-performance ratiometric probes requires distinct photophysical properties during recognition reaction process,which is closely related to their ICT characteristics.1,8-Naphthalimide is known as a typical fluorophore with desirable ICT property when functionalized with an electron-donating moiety at the para-position of the naphthalene chromophore.Although the photophysical properties of para-substituted 1,8-naphthalimide have been well studied,its meta-substituted counterpart has not been fully evaluated since the meta-position is conventionally thought to be weakly conjugated.Herein,combined experimental and theoretical studies are performed which consistently indicate that stronger charge transfer(CT) is exhibited by the meta-amino substituted 1,8-naphthalimide(m-NH_(2)) compared to the para-amino substituted one(p-NH_(2)).The ratiometric response of fluorescence with significant changes in wavelength and intensity upon acetylation(m-NAc and p-NAc) can be attributed to the larger ICT and stronger-NH_(2) vibrations.This observation is further demonstrated by deuterium oxide experiments,viscosity experiments and quantum chemical calculations.The practical application of meta-amino-1,8-naphthalimide ICT-based probes is also confirmed.This research is expected to bring an in-depth understanding of π-conjugated systems with ICT characteristics,and facilitates the design of sensitive ICT fluorescent probes with meta-amino substitution.
基金Supported by Fundamental Research Funds for the Central Universities(Grant No.2024QYBS031)Fundamental Research Funds for the Central Universities(Grant No.2022JBQY007)。
文摘Current research on rail vehicle system vibrations primarily relies on numerical methods,with vibration transfer functions commonly derived through data fitting.However,the physical mechanisms underlying these vibrations are not well understood.To clarify the vibration transfer function and its characteristics,four basic input vectors are defined,and an analytical method is proposed.The vibration transfer functions of the vehicle system are solved,and their spatial coherence is analyzed.The results show that there are two spatial scales and four coherent modes in the vehicle system.The track irregularity wavelengths are combined with two spatial scales to alter the proportions of basic input vectors and then show the characteristics of spatial coherence.Four coherent modes are involved in wheel-rail force and primary suspension force;two coherent modes are involved in bogie vertical motion;and their dominant modes vary with the input frequency.On the other hand,the coherent modes involved in the bogie pitching motion and vehicle body motion are single and fixed over the whole range of frequency.This study presents an analytical method for the rapid solution of dynamic responses in vehicle systems and systematically analyzes the coherence behavior of vibration transfer functions with respect to tracking irregularity wavelengths.
基金financial support was provided by the National Natural Science Foundation of China(Nos.52476146,52006008,and 52471219)the Guangdong Basic and Applied Basic Research Foundation(2023A1515140059 and 2025A1515011255)+2 种基金the Peking University Third Hospital Haidian transformation project(HDCXZHKC2023210)the National Foreign Expert Individual Human Project(Category H,No.H20240116)the State Key Laboratory of New Ceramic Materials Tsinghua University(No.KFZD202402).
文摘The latent heat thermal energy storage system with solid-liquid phase-change material(SLPCM-LHTES)as energy storage medium provides outstanding advantages such as system simplicity,stable temperature control,and high energy storage density,showing great potential toward addressing the energy storage problems associated with decentralized,intermittent,and unstable renewable energy sources.Notably,effective heat transfer within the SLPCM-LHTES is crucial for extending its application potential.Therefore,a comprehensive understanding of the heat transfer processes in SLPCM-LHTES from a theoretical perspective is necessary.In this review,we propose a three-stage heat transfer pathway in SLPCM-LHTES,including external heating,interfacial heat transfer,and intrinsic phase transition processes.From the perspective of this three-stage pathway,the theoretical basis of heat transfer processes and typical efficiency enhancement strategies in SLPCM-LHTES are summarized.Moreover,an overview of the typical applications of SLPCM-LHTES in various fields,such as building energy efficiency,textiles and garments,and battery thermal management,is presented.Finally,the remaining challenges and possible avenues of research in this burgeoning field will also be discussed.
基金supported by the National Natural Science Foundation of China(No.22273057)the Universities Joint Laboratory of Guangdong,Hong Kong and Macao(No.2021LSYS009)+2 种基金the Natural Science Foundation of Guangdong Province(Nos.2022A1515011661,2023A1515012631)the Chemistry and Chemical Engineering Guangdong Laboratory(No.1922003)Guangdong Major Project of Basic and Applied Basic Research(No.2019B030302009)。
文摘The excited state dynamics and critically regulated factors of reverse intersystem crossing(RISC)in through-space charge transfer(TSCT)molecules have received insufficient attention.Here,five molecules of through space/bond charge transfer inducing thermally activated delayed fluorescence(TADF)are prepared,and their excited state charge transfer processes are studied by ultrafast transient absorption and theoretical calculations.DM-Z has a largerΔEST,leading to a longer lifetime of intersystem crossing(ISC),resulting in the lowest photoluminescence quantum yield(PLQY).Oppositely,ISC and RISC are demonstrated to take place with shorter lifetimes for TSCT molecules.The face-to-faceπ-πstacking interactions and electron communication enable DM-B and DM-BX to have an efficient RISC,increasing the weight coefficient of RISC from 1.7%(DM-X)to close to 50%(DM-B and DM-BX)in the solvents,which make DM-BX and DM-B to have a high PLQY.However,partial local excitation in the donor center is observed and the charge transfer is decreased for DM-G and DM-X.The triplet excited state(DM-G)or singlet excited state(DM-X)mainly undergoes inactivation through a non-radiative relaxation process,resulting in less RISC and low PLQY.This work provides theoretical hints to enhance the RISC process in the TADF materials.
基金the National Natural Science Foundation of China(No.52205210)the Natural Science Foundation of Shandong Province(Nos.ZR2020MB018,ZR2022QE033 and ZR2021QB049).
文摘Achieving artificial simulations of multi-step energy transfer processes and conversions in nature remains a challenge.In this study,we present a three-step sequential energy transfer process,which was constructed through host-vip interactions between a piperazine derivative(PPE-BPI)with aggregationinduced emission(AIE)and cucurbit[7]uril(CB[7])in water to serve as ideal energy donors.To achieve multi-step sequential energy transfer,we employ three distinct fluorescent dyes Eosin B(EsB),Sulforhodamine 101(SR101),and Cyanine 5(Cy5)as energy acceptors.The PPE-PBI-2CB[7]+EsB+SR101+Cy5 system demonstrates a highly efficient three-step sequential energy transfer mechanism,starting with PPEPBI-2CB[7]and transferring energy successively to EsB,SR101,and finally to Cy5,with remarkable energy transfer efficiencies.More interestingly,with the progressive transfer of energy in the multi-step energy transfer system,the generation efficiency of superoxide anion radical(O_(2)•-)increased gradually,which can be used as photocatalysts for selectively photooxidation of N-phenyltetrahydroisoquinoline in an aqueous medium with a high yield of 86%after irradiation for 18 h.This study offers a valuable investigation into the simulation of multi-step energy transfer processes and transformations in the natural world,paving the way for further research in the field.
基金supported by the National Natural Science Foundation of China(Nos.41907325 and 41571470).
文摘The present study was conducted to examine the trophic transfer of potentially toxic elements(PTEs)in a closed arsenic mine.Eight PTEs in a soil-plant-leaf litter-earthworm-top predators(free-range local chicken and wild passerine bird)system were analyzed for nitrogen and carbon stable isotopes,PTE concentrations,bioaccumulation factors(BAFs),and transfer factors(TFs).The PTE concentrations in soils from mining areas were generally higher than a adjacent controlled area,with As and Cd in soils showing the prominent compared to other six PTEs,as seen for the indices of geo-accumulation index(I_(geo)),pollution index(PI)and potential ecological risk index(RI).The relatively high BAF and TF values suggested a distinct biotransfer of PTEs along the soil-plant-leaf litter-earthworm system.BAFs were mostly<1 except in earthworms,indicating that earthworms had a strong capacity to take up these metals.The TFs varied both among PTEs and organism’s species,e.g.,the transfer capacities of As in Pteris vittata and Pteris cretica,Cd in Miscanthus sinensis,and Pb,Cr and Mn in moss were the highest.For local free-range chicken and wild passerine bird,the concentrations of PTEs were higher in gastric contents and feather than in internal tissue(stomach,liver and heart),with lower contents in muscle and egg.Bioaccumulation of PTEs generally decreased from decomposer earthworms,to primary producer plants,to top predator,indicating a potential bio-dilution tendency in higher trophic levels in the terrestrial food chain.
基金funded by Sponsorship of Science and Technology Project of State Grid Xinjiang Electric Power Co.,Ltd.,grant number SGXJ0000TKJS2400168.
文摘This study presents an emergency control method for sub-synchronous oscillations in wind power gridconnected systems based on transfer learning,addressing the issue of insufficient generalization ability of traditional methods in complex real-world scenarios.By combining deep reinforcement learning with a transfer learning framework,cross-scenario knowledge transfer is achieved,significantly enhancing the adaptability of the control strategy.First,a sub-synchronous oscillation emergency control model for the wind power grid integration system is constructed under fixed scenarios based on deep reinforcement learning.A reward evaluation system based on the active power oscillation pattern of the system is proposed,introducing penalty functions for the number of machine-shedding rounds and the number of machines shed.This avoids the economic losses and grid security risks caused by the excessive one-time shedding of wind turbines.Furthermore,transfer learning is introduced into model training to enhance the model’s generalization capability in dealing with complex scenarios of actual wind power grid integration systems.By introducing the Maximum Mean Discrepancy(MMD)algorithm to calculate the distribution differences between source data and target data,the online decision-making reliability of the emergency control model is improved.Finally,the effectiveness of the proposed emergency control method for multi-scenario sub-synchronous oscillation in wind power grid integration systems based on transfer learning is analyzed using the New England 39-bus system.
基金financial support from the National Key R&D Program of China(Nos.2022YFB3503702,2023YFB3506901,2021YFB3501800)the National Natural Science Foundation of China(Nos.92156016,62104013,22071003)。
文摘Sensitization of metal-centered forbidden transitions is of great significance.Solid MnII-based phosphors with d-d forbidden transition sensitized by CeIIIwith d-f allowed transition are promising light conversion materials,but the energy transfer mechanism in CeIII-MnIIis still in dispute for the uncertainty of distances between metal centers.Herein,for the first time,we explored the energy transfer mechanism in two well-designed luminescent heteronuclear complexes with clear crystal structures,i.e.,Ce-N8-Mn and Ce-N2O6-Mn(N8=1,4,7,10,13,16,21,24-octaazabicyclo[8.8.8]hexacosane;N2O6=4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo[8.8.8]hexacosane).Short distances between metal centers facilitate efficient energy transfer from CeIIIto MnIIin both complexes,resulting in high photoluminescence quantum yield up to unity.After systematic study of the two heteronuclear complexes as well as two reference complexes Ce(N8)Br3and Ce(N2O6)Br3,we concluded that dipole-quadrupole interaction is the dominant energy transfer mechanism in the heteronuclear complexes.
文摘The ammunition loading system manipulator is susceptible to gear failure due to high-frequency,heavyload reciprocating motions and the absence of protective gear components.After a fault occurs,the distribution of fault characteristics under different loads is markedly inconsistent,and data is hard to label,which makes it difficult for the traditional diagnosis method based on single-condition training to generalize to different conditions.To address these issues,the paper proposes a novel transfer discriminant neural network(TDNN)for gear fault diagnosis.Specifically,an optimized joint distribution adaptive mechanism(OJDA)is designed to solve the distribution alignment problem between two domains.To improve the classification effect within the domain and the feature recognition capability for a few labeled data,metric learning is introduced to distinguish features from different fault categories.In addition,TDNN adopts a new pseudo-label training strategy to achieve label replacement by comparing the maximum probability of the pseudo-label with the test result.The proposed TDNN is verified in the experimental data set of the artillery manipulator device,and the diagnosis can achieve 99.5%,significantly outperforming other traditional adaptation methods.
文摘Industry and energy continue to require piston engines(PICE)at a high level worldwide.Therefore,science and technology must urgently work on improving the PICE working cycle.Improving the quality of the intake process of theworking fluid into the cylinder is one of the most effective ways to improve the operational performance of PICE.The purpose of the study was to assess the impact of various cylinder head(CylH)designs on the gas-dynamic and heat-exchange qualities of air flows within an engine model’s intake system.Three different CylH designs were studied:the basic configuration and upgraded cylinder heads with a square valve and a square valve port.These designs are innovative.Laboratory conditions were used to conduct the studies for stationary air flow.The experiments covered the range of Reynolds numbers from 8500 to 96,000.The intake system’s gas dynamics and heat transfer were determined using the thermal anemometry method,which was based on constant-temperature hot-wire anemometers.It has been established that the use of upgraded CylHs causes an increase in the turbulence number of flow by an average of 13.5%.Additionally,itwas found that the increase in the turbulence number of flowin the cylinder is about 19%when installing new CylH designs.It was shown that therewas an increase in the heat transfer coefficient in the intake pipe by 10%–40%when installing modernized CylH designs in the intake system.The article focused on the problems of increasing the turbulence level and intensifying the heat transfer of stationary air flow in the intake system,specifically in PICEs.The study’s findings are novel in the areas of applied gas dynamics and PICEs.
文摘This study introduces a Transformer-based multimodal fusion framework for simulating multiphase flow and heat transfer in carbon dioxide(CO_(2))–water enhanced geothermal systems(EGS).The model integrates geological parameters,thermal gradients,and control schedules to enable fast and accurate prediction of complex reservoir dynamics.The main contributions are:(i)development of a workflow that couples physics-based reservoir simulation with a Transformer neural network architecture,(ii)design of physics-guided loss functions to enforce conservation of mass and energy,(iii)application of the surrogate model to closed-loop optimization using a differential evolution(DE)algorithm,and(iv)incorporation of economic performance metrics,such as net present value(NPV),into decision support.The proposed framework achieves root mean square error(RMSE)of 3–5%,mean absolute error(MAE)below 4%,and coefficients of determination greater than 0.95 across multiple prediction targets,including production rates,pressure distributions,and temperature fields.When compared with recurrent neural network(RNN)baselines such as gated recurrent units(GRU)and long short-term memory networks(LSTM),as well as a physics-informed reduced-order model,the Transformer-based approach demonstrates superior accuracy and computational efficiency.Optimization experiments further show a 15–20%improvement in NPV,highlighting the framework’s potential for real-time forecasting,optimization,and decision-making in geothermal reservoir engineering.
基金supported in part by the Natural Science Foundation of China(NSFC)under Grant 61971102in part by the Key Research and Development Program of Zhejiang Province under Grant 2022C01093.
文摘In indoor environments,various batterypowered Internet of Things(IoT)devices,such as remote controllers and electronic tags on high-level shelves,require efficient energy management.However,manually monitoring remaining energy levels and battery replacement is both inadequate and costly.This paper introduces an energy management system for indoor IoT,which includes a mobile energy station(ES)for enabling on-demand wireless energy transfer(WET)in radio frequency(RF),some energy receivers(ERs),and a cloud server.By implementing a two-stage positioning system and embedding energy receivers into traditional IoT devices,we robustly manage their energy storage.The experimental results demonstrate that the energy receiver can harvest a minimum power of 58 mW.
基金supported by the National Key Research and Development Program of China(Grant No.2024YFA1408900)the National Natural Science Foundation of China(Grant Nos.12264040,12374333,and U21A20436)+2 种基金the Jiangxi Natural Science Foundation(Grant Nos.20232BCJ23022 and 20252BAC240119)the Innovation Program for Quantum Science and Technology(Grant No.2021ZD0301705)the Jiangxi Province Key Laboratory of Applied Optical Technology(Grant No.2024SSY03051)。
文摘Realizing efficient and controlled state transfers is necessary for implementing a wide range of classical and quantum information protocols.Recent studies have demonstrated that both asymmetric and symmetric state transfers can be achieved by encircling an exceptional point(EP)in non-Hermitian(NH)systems.However,the application of this phenomenon has been restricted to scenarios where an EP exists in single-qubit systems and is associated with a specific type of dissipation.In this work,we demonstrate efficient and controlled symmetric and asymmetric Bell-state transfers by modulating system parameters within a Jaynes-Cummings model while accounting for atomic spontaneous emission and cavity decay.The effective suppression of nonadiabatic transitions enables a symmetric exchange of Bell states irrespective of the encircling direction.Furthermore,we report a counterintuitive finding:the presence of an EP is not indispensable for implementing asymmetric state transfers in NH systems.We achieve perfect asymmetric Bell-state transfers even in the absence of an EP by dynamically orbiting around an approximate EP.Our work presents an approach to effectively and reliably manipulate entangled states with both symmetric and asymmetric characteristics,through dissipation engineering in NH systems.
文摘This study investigates the enhancement of convective heat transfer in a serpentine pipe using ferrofluid flow influenced by dual non-uniform magnetic sources.The primary objective is to improve thermal performance in compact cooling systems,such as those used in heat exchangers.A two-dimensional,steady-state Computational Fluid Dynamic(CFD)model is developed in ANSYS Fluent to simulate the behavior of an incompressible ferrofluid under applied constant heat flux and magnetic fields.The magnetic force is modeled using the Kelvin force,which acts on magnetized nanoparticles in response to spatially varying electromagnetic fields generated by two strategically positioned current-carrying wires.The effects of magnetic field strength,quantified by the magnetic number(Mn),on flow behavior and temperature distribution are thoroughly analyzed.The results indicate that increasing Mn leads to higher Nusselt numbers,demonstrating enhanced convective heat transfer.Secondary vortices induced by magnetic forcing improve fluid mixing,particularly in curved regions of the pipe.A mesh-independence study and model validation with benchmark data support the reliability of the numerical framework.This work highlights the potential of magnetic-field-assisted thermal control in energy-efficient cooling applications and provides a foundation for the further development of advanced ferrofluid-based heat transfer systems.
文摘Accurate assessment of seismic landslide susceptibility is crucial for disaster prevention and emergency decision-making.Although machine learning methods have been widely applied in this field,they exhibit a strong dependence on large quantities of highquality samples,resulting in significantly low prediction accuracy of existing studies under data-scarce or crossregional prediction scenarios,which fail to meet practical application requirements.To address this issue,this study proposes an intelligent prediction model integrating transfer learning and a sampling optimization strategy,aiming to enhance the accuracy and applicability of seismic landslide susceptibility assessment.The model first improves the sample collection method through the sampling optimization strategy to enhance the precision and representativeness of training samples.This not only ensures the accuracy of origin area training but also further strengthens the model's predictive ability in the target area.Subsequently,it incorporates Transfer Component Analysis(TCA)to overcome the differences in environmental characteristics between the origin area and target area,and couples TCA with the Light GBM algorithm to construct the TCA-Light GBM model,realizing the assessment of seismic landslide susceptibility in sample-free areas.Validated through case studies of the Jiuzhaigou and Luding earthquakes,the results demonstrate that the proposed TCALight GBM transfer learning method exhibits excellent applicability in seismic landslide susceptibility prediction.After optimization with the TCA algorithm,the model's prediction performance in the target domain is significantly improved,with the AUC value increasing from 0.719 to 0.827,representing an increase of approximately 15.02%.This indicates that TCA technology can effectively alleviate the feature distribution discrepancy between the source domain and target domain,enhancing the model's generalization ability.The method is particularly suitable for scenarios with data scarcity and cross-regional prediction and can provide reliable technical support for the emergency response and risk prevention and control of seismic hazards.
基金National Natural Science Foundation of China (Nos.22071185 and 22271224)the Fundamental Research Funds for the Central Universities (No.2042019kf0008)Wuhan University startup funding for financial support。
文摘The development of catalytic multicomponent reactions for constructing complex organic scaffolds from readily accessible commodity chemicals is a key pursuit in contemporary synthetic chemistry.Current methods for synthesizing thioesters primarily rely on the acylation of thiols,which produces substantial waste and requires malodorous,unstable sulfur sources.In this work,we introduce a photocatalyzed hydrogen transfer strategy that enables a three-component synthesis of thioesters using abundant primary alcohols,easily available alkenes and elemental sulfur under mild conditions.This protocol demonstrates broad applicability and high chemo-and regioselectivity for both primary alcohols and alkenes,highlighting the advantage and potential of photo-mediated hydrogen transfer in facilitating multicomponent reactions using primary alcohol and elemental sulfur feedstocks.
