Recently,one of the main challenges facing the smart grid is insufficient computing resources and intermittent energy supply for various distributed components(such as monitoring systems for renewable energy power sta...Recently,one of the main challenges facing the smart grid is insufficient computing resources and intermittent energy supply for various distributed components(such as monitoring systems for renewable energy power stations).To solve the problem,we propose an energy harvesting based task scheduling and resource management framework to provide robust and low-cost edge computing services for smart grid.First,we formulate an energy consumption minimization problem with regard to task offloading,time switching,and resource allocation for mobile devices,which can be decoupled and transformed into a typical knapsack problem.Then,solutions are derived by two different algorithms.Furthermore,we deploy renewable energy and energy storage units at edge servers to tackle intermittency and instability problems.Finally,we design an energy management algorithm based on sampling average approximation for edge computing servers to derive the optimal charging/discharging strategies,number of energy storage units,and renewable energy utilization.The simulation results show the efficiency and superiority of our proposed framework.展开更多
Hydrogen energy,with its abundant reserves,green and low-carbon characteristic,high energy density,diverse sources,and wide applications,is gradually becoming an important carrier in the global energy transformation a...Hydrogen energy,with its abundant reserves,green and low-carbon characteristic,high energy density,diverse sources,and wide applications,is gradually becoming an important carrier in the global energy transformation and development.In this paper,the off-grid wind power hydrogen production system is considered as the research object,and the operating characteristics of a proton exchange membrane(PEM)electrolysis cell,including underload,overload,variable load,and start-stop are analyzed.On this basis,the characteristic extraction of wind power output data after noise reduction is carried out,and then the self-organizing mapping neural network algorithm is used for clustering to extract typical wind power output scenarios and perform weight distribution based on the statistical probability.The trend and fluctuation components are superimposed to generate the typical operating conditions of an off-grid PEM electrolytic hydrogen production system.The historical output data of an actual wind farm are used for the case study,and the results confirm the feasibility of the method proposed in this study for obtaining the typical conditions of off-grid wind power hydrogen production.The results provide a basis for studying the dynamic operation characteristics of PEM electrolytic hydrogen production systems,and the performance degradation mechanism of PEM electrolysis cells under fluctuating inputs.展开更多
This study explores a novel strategy to enhance the hydrogen evolution reaction(HER)activity of carbon-supported rock salt-type NiCo_(2)(O,F)_(3) nanorods through lattice modifications induced by fluorine and excess a...This study explores a novel strategy to enhance the hydrogen evolution reaction(HER)activity of carbon-supported rock salt-type NiCo_(2)(O,F)_(3) nanorods through lattice modifications induced by fluorine and excess amorphous carbon.X-ray absorption near-edge structure(XANES)analysis confirmed that Co and Ni predominantly exist in the+2 oxidation state,whereas extended X-ray absorption fine structure(EXAFS)analysis revealed shortened Co-O and Co-Co bond lengths,indicating lattice distortions.Rietveld refinement and electron microscopy confirmed the formation of a homogeneous solid solution(NixCo_(2-x)(O,F)_(3))rather than a simple CoO/NiO composite.The optimized material(AH-2)exhibited the lowest overpotential(145 mV at 10 mA cm^(-1))and the smallest Tafel slope(98 mV dec^(-1)),attributed to its balanced phase composition,enhanced electronic conductivity,and synergistic effects of carbon and fluorine incorporation.Electrochemical impedance spectroscopy(EIS)confirmed improved charge transfer efficiency,correlating with enhanced catalytic activity.These findings provide critical insights into the tunability of transition metal oxide catalysts via controlled lattice modifications,offering a promising avenue for developing cost-effective and efficient electrocatalysts for sustainable hydrogen production.展开更多
To predict the lithium-ion(Li-ion)battery degradation trajectory in the early phase,arranging the maintenance of battery energy storage systems is of great importance.However,under different operation conditions,Li-io...To predict the lithium-ion(Li-ion)battery degradation trajectory in the early phase,arranging the maintenance of battery energy storage systems is of great importance.However,under different operation conditions,Li-ion batteries present distinct degradation patterns,and it is challenging to capture negligible capacity fade in early cycles.Despite the data-driven method showing promising performance,insufficient data is still a big issue since the ageing experiments on the batteries are too slow and expensive.In this study,we proposed twin autoencoders integrated into a two-stage method to predict the early cycles'degradation trajectories.The two-stage method can properly predict the degradation from course to fine.The twin autoencoders serve as a feature extractor and a synthetic data generator,respectively.Ultimately,a learning procedure based on the long-short term memory(LSTM)network is designed to hybridize the learning process between the real and synthetic data.The performance of the proposed method is verified on three datasets,and the experimental results show that the proposed method can achieve accurate predictions compared to its competitors.展开更多
Current treatments for glioblastoma face challenges such as the blood-brain barrier and lack of targeted therapy,compounded by the aggressive nature,high invasiveness,and heterogeneity of the disease.Exosomes,a subtyp...Current treatments for glioblastoma face challenges such as the blood-brain barrier and lack of targeted therapy,compounded by the aggressive nature,high invasiveness,and heterogeneity of the disease.Exosomes,a subtype of extracellular vesicles are emerging as promising nanocarrier drug delivery systems to address these limitations.Exosomes released by all cell types can be easily obtained and modified as delivery vehicles or therapeutic agents.A systematic review was conducted to evaluate various methods for exosome isolation,characterization,engineering or modification,drug loading and delivery efficiency,including exosome biodistribution and treatment efficacy.A search of four databases for in vitro and in vivo studies(2000–,2023)identified 6165 records,of which 23 articles were found eligible and included for analyses.Most studies applied ultracentrifugation(UC)for exosomes isolation.Cancer cell lines being the most frequently used source of exosomes,followed by stem cells.The incubation approach was predominantly utilized to modify exosomes for drug loading.In vivo analysis showed that exosome biodistribution was primarily concentrated in the brain region,peaking in the first 6 h and remained moderately high.Compared to native exosomes and untreated control groups,utilizing modified native exosomes(cargo loaded)for treating glioblastoma disease models led to more pronounced suppression of tumor growth and proliferation,enhanced stimulation of immune response and apoptosis,effective restoration of drug chemosensitivity,increased anti-tumor effect and prolonged survival rates.Modified exosomes whether through incubation,sonication,transfection,freeze-thawing or their combination,improve targeted delivery and therapeutic efficacy against glioblastoma.展开更多
CRISPR-Cas system permanently deletes any harmful gene-of-interest to combat cancer growth.Chitosan(CS)is a potential cancer therapeutic that mediates via PI3K/Akt/mTOR,MAPK and NF-kβsignaling pathway modulation.CS a...CRISPR-Cas system permanently deletes any harmful gene-of-interest to combat cancer growth.Chitosan(CS)is a potential cancer therapeutic that mediates via PI3K/Akt/mTOR,MAPK and NF-kβsignaling pathway modulation.CS and its covalent derivatives have been designed as nanocarrier of CRISPR-Cas9 alone(plasmid or ribonucleoprotein)or in combination with chemical drug for cancer treatment.The nanocarrier was functionalized with polyethylene glycol(PEG),targeting ligand,cell penetrating ligand and its inherent positive zeta potential to mitigate premature clearance and particulate aggregation,and promote cancer cell/nucleus targeting and permeabilization to enable CRISPR-Cas9 acting on the host DNA.Different physicochemical attributes are required for the CS-based nanocarrier to survive from the administration site,through the systemic circulation-extracellular matrix-mucus-mucosa axis,to the nucleus target.CRISPR-Cas9 delivery is met with heterogeneous uptake by the cancer cells.Choice of excipients such as targeting ligand and PEG may be inappropriate due to lacking overexpressed cancer receptor or availability of excessive metabolizing enzyme and immunoglobulin that defies the survival and action of these excipients rendering nanocarrier fails to reach the target site.Cancer omics analysis should be implied to select excipients which meet the pathophysiological needs,and chitosan nanocarrier with a“transformative physicochemical behavior”is essential to succeed CRISPR-Cas9 delivery.展开更多
In multi-infeed HVDC system, the interactions and influences between DC systems AC systems are complex as the electrical distances among DC converter stations which are relatively short. Multi-infeed interaction facto...In multi-infeed HVDC system, the interactions and influences between DC systems AC systems are complex as the electrical distances among DC converter stations which are relatively short. Multi-infeed interaction factor (MIIF) can effectively reflect the interaction among DC systems. The paper theoretically analyzes the impact factors of MIIF like the electrical distances between two DC converter stations and the equivalent impedance of the receiving end AC system. By applying the Kirchhoff’s current law on the inverter AC bus, the paper deduces the analytical expressions for MIIF. From the expression, it is clear how the equivalent impedance of AC system and coupling impedance can affect MIIF. PSCAD simulations validate the effectiveness and the correctness of the proposed expression and some useful conclusions are drawn.展开更多
An inorganic potassium silicate coating with pigments of alumina,aluminum phosphate,NiCrAlY and copper chromite black was prepared on CB2 stainless steel.Oxidation behavior in either ambient air or O_(2)+H_(2) O mixtu...An inorganic potassium silicate coating with pigments of alumina,aluminum phosphate,NiCrAlY and copper chromite black was prepared on CB2 stainless steel.Oxidation behavior in either ambient air or O_(2)+H_(2) O mixture at 630℃ for 2000 h was comparatively studied,and the coating exhibited excellent resistance under both test conditions.The water vapor considerably accelerated the oxidation of the uncoated CB2 steel,as the hydroxide,the main constituent of the coating,had a negligible evaporation rate at test temperature,while it had a limited effect on the coated sample.Meanwhile,the existence of coating may prolong or eliminate the incubation period in the O_(2)+H_(2) O mixture at 630℃.After oxidation,the coating matrix is in an amorphous state and fillers as alumina and copper chromite black are stable in the coating.Leucite(KAlSi_(2) O_(6))formed by Al from NiCrAlY and potassium silicate in the coatings was detected after tests either in O_(2) or O_(2)+H_(2) O mixture.展开更多
Nowadays,ensuring thequality of networkserviceshas become increasingly vital.Experts are turning toknowledge graph technology,with a significant emphasis on entity extraction in the identification of device configurat...Nowadays,ensuring thequality of networkserviceshas become increasingly vital.Experts are turning toknowledge graph technology,with a significant emphasis on entity extraction in the identification of device configurations.This research paper presents a novel entity extraction method that leverages a combination of active learning and attention mechanisms.Initially,an improved active learning approach is employed to select the most valuable unlabeled samples,which are subsequently submitted for expert labeling.This approach successfully addresses the problems of isolated points and sample redundancy within the network configuration sample set.Then the labeled samples are utilized to train the model for network configuration entity extraction.Furthermore,the multi-head self-attention of the transformer model is enhanced by introducing the Adaptive Weighting method based on the Laplace mixture distribution.This enhancement enables the transformer model to dynamically adapt its focus to words in various positions,displaying exceptional adaptability to abnormal data and further elevating the accuracy of the proposed model.Through comparisons with Random Sampling(RANDOM),Maximum Normalized Log-Probability(MNLP),Least Confidence(LC),Token Entrop(TE),and Entropy Query by Bagging(EQB),the proposed method,Entropy Query by Bagging and Maximum Influence Active Learning(EQBMIAL),achieves comparable performance with only 40% of the samples on both datasets,while other algorithms require 50% of the samples.Furthermore,the entity extraction algorithm with the Adaptive Weighted Multi-head Attention mechanism(AW-MHA)is compared with BILSTM-CRF,Mutil_Attention-Bilstm-Crf,Deep_Neural_Model_NER and BERT_Transformer,achieving precision rates of 75.98% and 98.32% on the two datasets,respectively.Statistical tests demonstrate the statistical significance and effectiveness of the proposed algorithms in this paper.展开更多
Voltage source converter based high voltage direct current(VSC-HVDC)can participate in voltage regulation by flexible control to help maintain the voltage stability of the power grid.In order to quantitatively evaluat...Voltage source converter based high voltage direct current(VSC-HVDC)can participate in voltage regulation by flexible control to help maintain the voltage stability of the power grid.In order to quantitatively evaluate its influence on the voltage interaction between VSC-HVDC and line commutated converter based high voltage direct current(LCC-HVDC),this paper proposes a hybrid multi-infeed interaction factor(HMIIF)calculation method considering the voltage regulation control characteristics of VSC-HVDC.Firstly,for a hybrid multi-infeed high voltage direct current system,an additional equivalent operating admittance matrix is constructed to characterize HVDC equipment characteristics under small disturbance.Secondly,based on the characteristic curve between the reactive power and the voltage of a certain VSC-HVDC project,the additional equivalent operating admittance of VSC-HVDC is derived.The additional equivalent operating admittance matrix calculation method is proposed.Thirdly,the equivalent bus impedance matrix is obtained by modifying the alternating current(AC)system admittance matrix with the additional equivalent operating admittance matrix.On this basis,the HMIIF calculation method based on the equivalent bus impedance ratio is proposed.Finally,the effectiveness of the proposed method is verified in a hybrid dual-infeed high voltage direct current system constructed in Power Systems Computer Aided Design(PSCAD),and the influence of voltage regulation control on HMIIF is analyzed.展开更多
The advent of the big data era has provided many types of transportation datasets,such as metro smart card data,for studying residents’mobility and understanding how their mobility has been shaped and is shaping the ...The advent of the big data era has provided many types of transportation datasets,such as metro smart card data,for studying residents’mobility and understanding how their mobility has been shaped and is shaping the urban space.In this paper,we use metro smart card data from two Chinese metropolises,Shanghai and Shenzhen.Five metro mobility indicators are introduced,and association rules are established to explore the mobility patterns.The proportion of people entering and exiting the station is used to measure the jobs-housing balance.It is found that the average travel distance and duration of Shanghai passengers are higher than those of Shenzhen,and the proportion of metro commuters in Shanghai is higher than that of Shenzhen.The jobs-housing spatial relationship in Shenzhen based on metro travel is more balanced than that in Shanghai.The fundamental reason for the differences between the two cities is the difference in urban morphology.Compared with the monocentric structure of Shanghai,the polycentric structure of Shenzhen results in more scattered travel hotspots and more diverse travel routes,which helps Shenzhen to have a better jobs-housing balance.This paper fills a gap in comparative research among Chinese cities based on transportation big data analysis.The results provide support for planning metro routes,adjusting urban structure and land use to form a more reasonable metro network,and balancing the jobs-housing spatial relationship.展开更多
The effects of homogenization parameters on the microstructure evolution and tensile behavior of a balanced Al−Mg−Si alloy were investigated using the optical microscope,scanning electron microscope,X-ray diffraction,...The effects of homogenization parameters on the microstructure evolution and tensile behavior of a balanced Al−Mg−Si alloy were investigated using the optical microscope,scanning electron microscope,X-ray diffraction,electron probe microanalyzer,differential scanning calorimetry,electrical conductivity test,and tensile test.The results show that Mg_(2)Si andβ-AlFeSi are the main intermetallic compounds in the as-cast structure,and Mg solute microsegregation is predominant inside the dendrite cell.The prediction of the full dissolution time of Mg_(2)Si by a kinetic model is consistent with the experiment.Theβ-AlFeSi in the alloy exhibits high thermal stability and mainly undergoes dissolution and coarsening during homogenization at 560℃,and only a small portion is converted toα-AlFeSi.The optimal homogenization parameters are determined as 560℃and 360 min,when considering the evolution of microstructure and resource savings.Both the strength and ductility of the alloy increased after homogenization.展开更多
The present study focuses on the synthesis and characterization of lanthanum(La^(3+))-doped calcium nanoferrites(CaLa_(x)Fe_(2-x)O_(4):x=0.025,0.050,0.075 and 0.100)using the sonochemical method.Various techniques wer...The present study focuses on the synthesis and characterization of lanthanum(La^(3+))-doped calcium nanoferrites(CaLa_(x)Fe_(2-x)O_(4):x=0.025,0.050,0.075 and 0.100)using the sonochemical method.Various techniques were employed to analyze the effect of La^(3+)infusion,Raman spectroscopy confirms the presence of active A_(1g),T_(2g)and E_g modes in the CaLa_(x)Fe_(2-x)O_(4)nanoferrite,indicating the formation of an active ferrite system.The introduction of La^(3+)doping results in a significant increase in the band gap energy,rendering the nanoferrites insulating(3.23-3,57 eV).At higher frequencies,the impedance studies reveal minimal losses and better AC conductivity,pointing to improved dielectric characteristics.At higher frequencies,the Q-factor of La-doped calcium nanoferrites shows lower electromagnetic losses.The M-H curve exhibits ferromagnetic behavior,with La^(3+)-doped calcium nano ferrites displaying a saturation magnetization ranging from 12.72 to 18.10 emu/g.The incorporation of La^(3+)also induces enhanced electrical polarization,leading to notable dielectric loss and increased absorption of electromagnetic waves.Consequently,these CaLa_(x)Fe_(2-x)O_(4)nanoferrites demonstrate potential as effective microwave absorbers across a wide frequency range,with significant shielding absorption observed at 8.8-9.1 GHz.展开更多
The Lao.67Mg0.33Ni2.5Co0.5 hydrogen storage alloy was prepared by the vacuum intermediate frequency induction furnace followed by annealing treatment. The pulverization degree of both the as-cast and annealed alloy po...The Lao.67Mg0.33Ni2.5Co0.5 hydrogen storage alloy was prepared by the vacuum intermediate frequency induction furnace followed by annealing treatment. The pulverization degree of both the as-cast and annealed alloy powders after gaseous hydriding and dehydriding cycle was investigated and the discovery was that annealing treatment could hardly ameliorate their anti-pulverization ability. The element content of La, Mg, Ni and Co existing in electrolyte before and after the electrochemical cycles by using ICP-AES technology was also analyzed and it showed that a large amount of La and Mg were dissolved in the electrolyte, but the amount of dissolution for La and Mg significantly declined when the alloy was annealed. The XRD analysis revealed that all the al- loys consisted of two main phases AB3 and AB2 and a residual phase AB5 while annealing treatment made the AB2 phase decrease slightly. Furthermore, the anti-corrosion abilities of various elements in different phases of the as-cast and annealed alloy samples were studied by analyzing the element （La, Mg, Ni, Co） change with the corrosion time in phases AB3 and AB2 by means of EDS. It turned out that the element of La was mainly corroded out from the phase AB2 while not easily from the phase AB3. However, the element of Mg was both easily corroded out from the phases AB2 and AB3, but the corrosion was more obvious in the phase AB3. Therefore, annealing improved the anti-corrosion performances of La and Mg in the phase AB2.展开更多
The significant occupancy of {411}〈148〉texture exists in the thin-gauge grain-oriented silicon steel(TGCRGO is defined that thickness of the sheet is〈0.25 mm and the reduction in cold rolling is more than 90%) whic...The significant occupancy of {411}〈148〉texture exists in the thin-gauge grain-oriented silicon steel(TGCRGO is defined that thickness of the sheet is〈0.25 mm and the reduction in cold rolling is more than 90%) which has been considered to have obviously effects on the abnormal growth of Goss-oriented grains during the secondary recrystallization process. The microstructures of the TG-CRGO were investigated by X-ray diffraction and electron back-scattered diffraction in this study. It was found that {411}〈148〉〉texture mainly exists in the center layer of hot-rolled as well as normalized plates.With the increase in cold rolling reduction, {411}〈148〉 orientation gradually rotates to a-fiber texture(〈110〉//RD).Finally, few {411}〈148〉would retain at the boundaries of deformed a-fiber grains(〈110〉//RD) as the reduction in cold rolling reaches 90%. After annealing treatment, a small amount of c-fiber textures(〈111〉//ND) preferably nucleates and recrystallizes between the DBs(deformation bands) at first; then, the {411}〈148〉 recrystallization texture occurs and mainly nucleates at the grains boundaries of the deformed a-fiber grains, and also quite a few {411}〈148〉orientation grains nucleate in the inner of {112}〈110〉grains. But this phenomenon was not observed in the {100}〈011〉deformation grains.With respect to the occurrence of {411}〈148〉recrystallization texture, it is mainly induced by strong a-fiber as well as weak c-fiber textures formed during cold rolling other than originating from {411}〈148〉 regions in hot bands.展开更多
Electrolysis is a promising technology to improve sludge dewaterability efficiently with negligible environmental impact. To intensify the electrolytic efficiency, the effect of electrolytes(NaCl, Na_2SO_4, NaNO_3, an...Electrolysis is a promising technology to improve sludge dewaterability efficiently with negligible environmental impact. To intensify the electrolytic efficiency, the effect of electrolytes(NaCl, Na_2SO_4, NaNO_3, and NaClO_4) on electrolysis pretreatment of municipal sludge and its mechanisms was investigated using Ti/PbO_2 electrodes. The electrolytes,which enhanced the production of oxidative radicals, showed a significant synergetic effect in reducing the capillary suction time(CST) of sludge. NaCl was distinguished from the other electrolytes since it formed a large amount of active chlorine species, which oxidized the sludge cells to improve the sludge dewaterability. The surface morphologies as well as the soluble proteins and polysaccharides were analyzed to unravel the underlying mechanisms of sludge dewaterability. Additionally, an economic assessment showed that NaCl addition in the electrolysis pretreatment can be a suitable technique for enhancing municipal sludge dewaterability.展开更多
Hydrogen energy,whether in generation plants or utilization facilities,plays a decisive role in the mission to achieve net-zero greenhouse gas emissions,all to minimize pollution.The growing demand for clean energy ca...Hydrogen energy,whether in generation plants or utilization facilities,plays a decisive role in the mission to achieve net-zero greenhouse gas emissions,all to minimize pollution.The growing demand for clean energy carrier steadily accelerates the development of hydrogen production processes,and therein proton exchange membrane(PEM)water electrolysis is deemed a promising long-term strategy for hydrogen preparation and collection.This review retrospects recent developments and applications of bipolar plates(BPs)as key components in PEM fuel cells and water electrolysers.The main content includes multifaceted challenges in the R&D or fabrication of BPs and potential future trends have also been proposed.Specific details cover the BPs matrix(metallic materials and carbon composites)and the surface coating types(metal and compound coatings,carbon-based coatings,and polymer coatings),as well as the influence of flow field design for mass transport.Long-term development and feasible researches of BPs are prospected.Especially in the following aspects:(1)Structural and functional integration of components,such as material fabrication and flow field geometry optimization using 3D printing technology;(2)Introduction of environment-friendly renewable energy for hydrogen production;(3)Research on hydrogen energy reversible systems;(4)Composition optimization of surface coatings based on computational materials science and(5)systematic design expected to evolve into the next generation of BPs.展开更多
At present,only a single modification method is adopted to improve the shortcomings of erythritol(ET)as a phase change material(PCM).Compared with a single modification method,the synergistic effect of multiple modifi...At present,only a single modification method is adopted to improve the shortcomings of erythritol(ET)as a phase change material(PCM).Compared with a single modification method,the synergistic effect of multiple modification methods can endow ET with comprehensive performance to meet the purpose of package,supercooling reduction,and enhancement of thermal conductivity.In this work,we innovatively combine graphene oxide(GO)nanosheet modified melamine foam(MF)and polyaniline(PANI)to construct a novel ET-based PCM by blending and porous material adsorption modification.PANI as the nucleation center can enhance the crystallization rate,thereby reducing the supercooling of ET.Meanwhile,GO@MF foam can not only be used as a porous support material to encapsulate ET but also as a heat conduction reinforcement to improve heat storage and release rate.As a result,the supercooling of GO@MF/PANI@ET(GMPET)composite PCM decreases from 91.2℃ of pure ET to 57.9℃ and its thermal conductivity(1.58 W·m^(-1)·K^(-1))is about three times higher than that of pure ET(0.57 W·m^(-1)·K^(-1)).Moreover,after being placed at 140℃ for 2 h,there is almost no ET leakage in the GMPET composite PCM,and the mass loss ratio is less than 0.75%.In addition,the GMPET composite PCM displays a high melting enthalpy of about 259 J·g^(-1) and a high initial mass loss temperature of about 198℃.Even after the 200th cycling test,the phase transition temperature and the latent heat storage capacity of the GMPET PCM all remain stable.This work offers an effective and promising strategy to design ET-based composite PCM for the field of energy storage.展开更多
基金supported in part by the National Natural Science Foundation of China under Grant No.61473066in part by the Natural Science Foundation of Hebei Province under Grant No.F2021501020+2 种基金in part by the S&T Program of Qinhuangdao under Grant No.202401A195in part by the Science Research Project of Hebei Education Department under Grant No.QN2025008in part by the Innovation Capability Improvement Plan Project of Hebei Province under Grant No.22567637H
文摘Recently,one of the main challenges facing the smart grid is insufficient computing resources and intermittent energy supply for various distributed components(such as monitoring systems for renewable energy power stations).To solve the problem,we propose an energy harvesting based task scheduling and resource management framework to provide robust and low-cost edge computing services for smart grid.First,we formulate an energy consumption minimization problem with regard to task offloading,time switching,and resource allocation for mobile devices,which can be decoupled and transformed into a typical knapsack problem.Then,solutions are derived by two different algorithms.Furthermore,we deploy renewable energy and energy storage units at edge servers to tackle intermittency and instability problems.Finally,we design an energy management algorithm based on sampling average approximation for edge computing servers to derive the optimal charging/discharging strategies,number of energy storage units,and renewable energy utilization.The simulation results show the efficiency and superiority of our proposed framework.
基金supported by the National Key Research and Development Program of China(Program Number 2021YFB4000100)the Beijing Postdoctoral Research Foundation(Grant Number 2023-ZZ-63).
文摘Hydrogen energy,with its abundant reserves,green and low-carbon characteristic,high energy density,diverse sources,and wide applications,is gradually becoming an important carrier in the global energy transformation and development.In this paper,the off-grid wind power hydrogen production system is considered as the research object,and the operating characteristics of a proton exchange membrane(PEM)electrolysis cell,including underload,overload,variable load,and start-stop are analyzed.On this basis,the characteristic extraction of wind power output data after noise reduction is carried out,and then the self-organizing mapping neural network algorithm is used for clustering to extract typical wind power output scenarios and perform weight distribution based on the statistical probability.The trend and fluctuation components are superimposed to generate the typical operating conditions of an off-grid PEM electrolytic hydrogen production system.The historical output data of an actual wind farm are used for the case study,and the results confirm the feasibility of the method proposed in this study for obtaining the typical conditions of off-grid wind power hydrogen production.The results provide a basis for studying the dynamic operation characteristics of PEM electrolytic hydrogen production systems,and the performance degradation mechanism of PEM electrolysis cells under fluctuating inputs.
基金supported by the Russian Science Foundation(project No.24-43-00215,http://rscf.ru/project/24-43-00215/).
文摘This study explores a novel strategy to enhance the hydrogen evolution reaction(HER)activity of carbon-supported rock salt-type NiCo_(2)(O,F)_(3) nanorods through lattice modifications induced by fluorine and excess amorphous carbon.X-ray absorption near-edge structure(XANES)analysis confirmed that Co and Ni predominantly exist in the+2 oxidation state,whereas extended X-ray absorption fine structure(EXAFS)analysis revealed shortened Co-O and Co-Co bond lengths,indicating lattice distortions.Rietveld refinement and electron microscopy confirmed the formation of a homogeneous solid solution(NixCo_(2-x)(O,F)_(3))rather than a simple CoO/NiO composite.The optimized material(AH-2)exhibited the lowest overpotential(145 mV at 10 mA cm^(-1))and the smallest Tafel slope(98 mV dec^(-1)),attributed to its balanced phase composition,enhanced electronic conductivity,and synergistic effects of carbon and fluorine incorporation.Electrochemical impedance spectroscopy(EIS)confirmed improved charge transfer efficiency,correlating with enhanced catalytic activity.These findings provide critical insights into the tunability of transition metal oxide catalysts via controlled lattice modifications,offering a promising avenue for developing cost-effective and efficient electrocatalysts for sustainable hydrogen production.
基金financially supported by the National Natural Science Foundation of China under Grant 62372369,52107229,62272383the Key Research and Development Program of Shaanxi Province(2024GX-YBXM-442)Natural Science Basic Research Program of Shaanxi Province(2024JC-YBMS-477)。
文摘To predict the lithium-ion(Li-ion)battery degradation trajectory in the early phase,arranging the maintenance of battery energy storage systems is of great importance.However,under different operation conditions,Li-ion batteries present distinct degradation patterns,and it is challenging to capture negligible capacity fade in early cycles.Despite the data-driven method showing promising performance,insufficient data is still a big issue since the ageing experiments on the batteries are too slow and expensive.In this study,we proposed twin autoencoders integrated into a two-stage method to predict the early cycles'degradation trajectories.The two-stage method can properly predict the degradation from course to fine.The twin autoencoders serve as a feature extractor and a synthetic data generator,respectively.Ultimately,a learning procedure based on the long-short term memory(LSTM)network is designed to hybridize the learning process between the real and synthetic data.The performance of the proposed method is verified on three datasets,and the experimental results show that the proposed method can achieve accurate predictions compared to its competitors.
基金supported by the Bridging Grant from Universiti Sains Malaysia (R501LR-RND003–0000001319–0000)funding through the Fundamental Research Grant Scheme (FRGS/1/2020/TK0/USM/02/32–6171275) awarded by the Ministry of Higher Education Malaysia
文摘Current treatments for glioblastoma face challenges such as the blood-brain barrier and lack of targeted therapy,compounded by the aggressive nature,high invasiveness,and heterogeneity of the disease.Exosomes,a subtype of extracellular vesicles are emerging as promising nanocarrier drug delivery systems to address these limitations.Exosomes released by all cell types can be easily obtained and modified as delivery vehicles or therapeutic agents.A systematic review was conducted to evaluate various methods for exosome isolation,characterization,engineering or modification,drug loading and delivery efficiency,including exosome biodistribution and treatment efficacy.A search of four databases for in vitro and in vivo studies(2000–,2023)identified 6165 records,of which 23 articles were found eligible and included for analyses.Most studies applied ultracentrifugation(UC)for exosomes isolation.Cancer cell lines being the most frequently used source of exosomes,followed by stem cells.The incubation approach was predominantly utilized to modify exosomes for drug loading.In vivo analysis showed that exosome biodistribution was primarily concentrated in the brain region,peaking in the first 6 h and remained moderately high.Compared to native exosomes and untreated control groups,utilizing modified native exosomes(cargo loaded)for treating glioblastoma disease models led to more pronounced suppression of tumor growth and proliferation,enhanced stimulation of immune response and apoptosis,effective restoration of drug chemosensitivity,increased anti-tumor effect and prolonged survival rates.Modified exosomes whether through incubation,sonication,transfection,freeze-thawing or their combination,improve targeted delivery and therapeutic efficacy against glioblastoma.
基金MOHE (FRGS/1/2023/STG05/UITM/01/3) for funding support
文摘CRISPR-Cas system permanently deletes any harmful gene-of-interest to combat cancer growth.Chitosan(CS)is a potential cancer therapeutic that mediates via PI3K/Akt/mTOR,MAPK and NF-kβsignaling pathway modulation.CS and its covalent derivatives have been designed as nanocarrier of CRISPR-Cas9 alone(plasmid or ribonucleoprotein)or in combination with chemical drug for cancer treatment.The nanocarrier was functionalized with polyethylene glycol(PEG),targeting ligand,cell penetrating ligand and its inherent positive zeta potential to mitigate premature clearance and particulate aggregation,and promote cancer cell/nucleus targeting and permeabilization to enable CRISPR-Cas9 acting on the host DNA.Different physicochemical attributes are required for the CS-based nanocarrier to survive from the administration site,through the systemic circulation-extracellular matrix-mucus-mucosa axis,to the nucleus target.CRISPR-Cas9 delivery is met with heterogeneous uptake by the cancer cells.Choice of excipients such as targeting ligand and PEG may be inappropriate due to lacking overexpressed cancer receptor or availability of excessive metabolizing enzyme and immunoglobulin that defies the survival and action of these excipients rendering nanocarrier fails to reach the target site.Cancer omics analysis should be implied to select excipients which meet the pathophysiological needs,and chitosan nanocarrier with a“transformative physicochemical behavior”is essential to succeed CRISPR-Cas9 delivery.
文摘In multi-infeed HVDC system, the interactions and influences between DC systems AC systems are complex as the electrical distances among DC converter stations which are relatively short. Multi-infeed interaction factor (MIIF) can effectively reflect the interaction among DC systems. The paper theoretically analyzes the impact factors of MIIF like the electrical distances between two DC converter stations and the equivalent impedance of the receiving end AC system. By applying the Kirchhoff’s current law on the inverter AC bus, the paper deduces the analytical expressions for MIIF. From the expression, it is clear how the equivalent impedance of AC system and coupling impedance can affect MIIF. PSCAD simulations validate the effectiveness and the correctness of the proposed expression and some useful conclusions are drawn.
基金financially supported by the National Natural Science Foundation of China(No.52001142).
文摘An inorganic potassium silicate coating with pigments of alumina,aluminum phosphate,NiCrAlY and copper chromite black was prepared on CB2 stainless steel.Oxidation behavior in either ambient air or O_(2)+H_(2) O mixture at 630℃ for 2000 h was comparatively studied,and the coating exhibited excellent resistance under both test conditions.The water vapor considerably accelerated the oxidation of the uncoated CB2 steel,as the hydroxide,the main constituent of the coating,had a negligible evaporation rate at test temperature,while it had a limited effect on the coated sample.Meanwhile,the existence of coating may prolong or eliminate the incubation period in the O_(2)+H_(2) O mixture at 630℃.After oxidation,the coating matrix is in an amorphous state and fillers as alumina and copper chromite black are stable in the coating.Leucite(KAlSi_(2) O_(6))formed by Al from NiCrAlY and potassium silicate in the coatings was detected after tests either in O_(2) or O_(2)+H_(2) O mixture.
基金supported by the National Key R&D Program of China(2019YFB2103202).
文摘Nowadays,ensuring thequality of networkserviceshas become increasingly vital.Experts are turning toknowledge graph technology,with a significant emphasis on entity extraction in the identification of device configurations.This research paper presents a novel entity extraction method that leverages a combination of active learning and attention mechanisms.Initially,an improved active learning approach is employed to select the most valuable unlabeled samples,which are subsequently submitted for expert labeling.This approach successfully addresses the problems of isolated points and sample redundancy within the network configuration sample set.Then the labeled samples are utilized to train the model for network configuration entity extraction.Furthermore,the multi-head self-attention of the transformer model is enhanced by introducing the Adaptive Weighting method based on the Laplace mixture distribution.This enhancement enables the transformer model to dynamically adapt its focus to words in various positions,displaying exceptional adaptability to abnormal data and further elevating the accuracy of the proposed model.Through comparisons with Random Sampling(RANDOM),Maximum Normalized Log-Probability(MNLP),Least Confidence(LC),Token Entrop(TE),and Entropy Query by Bagging(EQB),the proposed method,Entropy Query by Bagging and Maximum Influence Active Learning(EQBMIAL),achieves comparable performance with only 40% of the samples on both datasets,while other algorithms require 50% of the samples.Furthermore,the entity extraction algorithm with the Adaptive Weighted Multi-head Attention mechanism(AW-MHA)is compared with BILSTM-CRF,Mutil_Attention-Bilstm-Crf,Deep_Neural_Model_NER and BERT_Transformer,achieving precision rates of 75.98% and 98.32% on the two datasets,respectively.Statistical tests demonstrate the statistical significance and effectiveness of the proposed algorithms in this paper.
基金supported by the Technology Project of the State Grid Corporation Headquarters Management(Contract No.5100-202158467A-0-0-00).
文摘Voltage source converter based high voltage direct current(VSC-HVDC)can participate in voltage regulation by flexible control to help maintain the voltage stability of the power grid.In order to quantitatively evaluate its influence on the voltage interaction between VSC-HVDC and line commutated converter based high voltage direct current(LCC-HVDC),this paper proposes a hybrid multi-infeed interaction factor(HMIIF)calculation method considering the voltage regulation control characteristics of VSC-HVDC.Firstly,for a hybrid multi-infeed high voltage direct current system,an additional equivalent operating admittance matrix is constructed to characterize HVDC equipment characteristics under small disturbance.Secondly,based on the characteristic curve between the reactive power and the voltage of a certain VSC-HVDC project,the additional equivalent operating admittance of VSC-HVDC is derived.The additional equivalent operating admittance matrix calculation method is proposed.Thirdly,the equivalent bus impedance matrix is obtained by modifying the alternating current(AC)system admittance matrix with the additional equivalent operating admittance matrix.On this basis,the HMIIF calculation method based on the equivalent bus impedance ratio is proposed.Finally,the effectiveness of the proposed method is verified in a hybrid dual-infeed high voltage direct current system constructed in Power Systems Computer Aided Design(PSCAD),and the influence of voltage regulation control on HMIIF is analyzed.
基金National Key R&D Program of China(No.2019YFB2103102)Hong Kong Polytechnic University(No.CD06,P0042540)。
文摘The advent of the big data era has provided many types of transportation datasets,such as metro smart card data,for studying residents’mobility and understanding how their mobility has been shaped and is shaping the urban space.In this paper,we use metro smart card data from two Chinese metropolises,Shanghai and Shenzhen.Five metro mobility indicators are introduced,and association rules are established to explore the mobility patterns.The proportion of people entering and exiting the station is used to measure the jobs-housing balance.It is found that the average travel distance and duration of Shanghai passengers are higher than those of Shenzhen,and the proportion of metro commuters in Shanghai is higher than that of Shenzhen.The jobs-housing spatial relationship in Shenzhen based on metro travel is more balanced than that in Shanghai.The fundamental reason for the differences between the two cities is the difference in urban morphology.Compared with the monocentric structure of Shanghai,the polycentric structure of Shenzhen results in more scattered travel hotspots and more diverse travel routes,which helps Shenzhen to have a better jobs-housing balance.This paper fills a gap in comparative research among Chinese cities based on transportation big data analysis.The results provide support for planning metro routes,adjusting urban structure and land use to form a more reasonable metro network,and balancing the jobs-housing spatial relationship.
基金financially supported by State Grid Corporation of China (No.5500-202128250A-0-0-00)。
文摘The effects of homogenization parameters on the microstructure evolution and tensile behavior of a balanced Al−Mg−Si alloy were investigated using the optical microscope,scanning electron microscope,X-ray diffraction,electron probe microanalyzer,differential scanning calorimetry,electrical conductivity test,and tensile test.The results show that Mg_(2)Si andβ-AlFeSi are the main intermetallic compounds in the as-cast structure,and Mg solute microsegregation is predominant inside the dendrite cell.The prediction of the full dissolution time of Mg_(2)Si by a kinetic model is consistent with the experiment.Theβ-AlFeSi in the alloy exhibits high thermal stability and mainly undergoes dissolution and coarsening during homogenization at 560℃,and only a small portion is converted toα-AlFeSi.The optimal homogenization parameters are determined as 560℃and 360 min,when considering the evolution of microstructure and resource savings.Both the strength and ductility of the alloy increased after homogenization.
基金Project supported by the Strategic Academic Leadership Program of the Southern Federal University(Priority 2030)。
文摘The present study focuses on the synthesis and characterization of lanthanum(La^(3+))-doped calcium nanoferrites(CaLa_(x)Fe_(2-x)O_(4):x=0.025,0.050,0.075 and 0.100)using the sonochemical method.Various techniques were employed to analyze the effect of La^(3+)infusion,Raman spectroscopy confirms the presence of active A_(1g),T_(2g)and E_g modes in the CaLa_(x)Fe_(2-x)O_(4)nanoferrite,indicating the formation of an active ferrite system.The introduction of La^(3+)doping results in a significant increase in the band gap energy,rendering the nanoferrites insulating(3.23-3,57 eV).At higher frequencies,the impedance studies reveal minimal losses and better AC conductivity,pointing to improved dielectric characteristics.At higher frequencies,the Q-factor of La-doped calcium nanoferrites shows lower electromagnetic losses.The M-H curve exhibits ferromagnetic behavior,with La^(3+)-doped calcium nano ferrites displaying a saturation magnetization ranging from 12.72 to 18.10 emu/g.The incorporation of La^(3+)also induces enhanced electrical polarization,leading to notable dielectric loss and increased absorption of electromagnetic waves.Consequently,these CaLa_(x)Fe_(2-x)O_(4)nanoferrites demonstrate potential as effective microwave absorbers across a wide frequency range,with significant shielding absorption observed at 8.8-9.1 GHz.
基金Project supported by the National Key Laboratory of New Metal(Z2011-11)the National Natural Science Foundation of China(51471054)
文摘The Lao.67Mg0.33Ni2.5Co0.5 hydrogen storage alloy was prepared by the vacuum intermediate frequency induction furnace followed by annealing treatment. The pulverization degree of both the as-cast and annealed alloy powders after gaseous hydriding and dehydriding cycle was investigated and the discovery was that annealing treatment could hardly ameliorate their anti-pulverization ability. The element content of La, Mg, Ni and Co existing in electrolyte before and after the electrochemical cycles by using ICP-AES technology was also analyzed and it showed that a large amount of La and Mg were dissolved in the electrolyte, but the amount of dissolution for La and Mg significantly declined when the alloy was annealed. The XRD analysis revealed that all the al- loys consisted of two main phases AB3 and AB2 and a residual phase AB5 while annealing treatment made the AB2 phase decrease slightly. Furthermore, the anti-corrosion abilities of various elements in different phases of the as-cast and annealed alloy samples were studied by analyzing the element （La, Mg, Ni, Co） change with the corrosion time in phases AB3 and AB2 by means of EDS. It turned out that the element of La was mainly corroded out from the phase AB2 while not easily from the phase AB3. However, the element of Mg was both easily corroded out from the phases AB2 and AB3, but the corrosion was more obvious in the phase AB3. Therefore, annealing improved the anti-corrosion performances of La and Mg in the phase AB2.
基金financially supported by the China’s State Grid Corporation of Science and Technology Projects (No. SGRI-WD-71-13-002)the National Natural Science Foundation of China (No. 51171019)
文摘The significant occupancy of {411}〈148〉texture exists in the thin-gauge grain-oriented silicon steel(TGCRGO is defined that thickness of the sheet is〈0.25 mm and the reduction in cold rolling is more than 90%) which has been considered to have obviously effects on the abnormal growth of Goss-oriented grains during the secondary recrystallization process. The microstructures of the TG-CRGO were investigated by X-ray diffraction and electron back-scattered diffraction in this study. It was found that {411}〈148〉〉texture mainly exists in the center layer of hot-rolled as well as normalized plates.With the increase in cold rolling reduction, {411}〈148〉 orientation gradually rotates to a-fiber texture(〈110〉//RD).Finally, few {411}〈148〉would retain at the boundaries of deformed a-fiber grains(〈110〉//RD) as the reduction in cold rolling reaches 90%. After annealing treatment, a small amount of c-fiber textures(〈111〉//ND) preferably nucleates and recrystallizes between the DBs(deformation bands) at first; then, the {411}〈148〉 recrystallization texture occurs and mainly nucleates at the grains boundaries of the deformed a-fiber grains, and also quite a few {411}〈148〉orientation grains nucleate in the inner of {112}〈110〉grains. But this phenomenon was not observed in the {100}〈011〉deformation grains.With respect to the occurrence of {411}〈148〉recrystallization texture, it is mainly induced by strong a-fiber as well as weak c-fiber textures formed during cold rolling other than originating from {411}〈148〉 regions in hot bands.
基金support by National Natural Science Foundation of China(61202354,51507084)Nanjing University of Post and Telecommunications Science Foundation(NUPTSF)(NT214203)
基金supported by the National Nature Science Foundation of China (Nos.21547011,21307036,51708356)the Natural Science Foundation of Guangdong Province (No.2014A030313761)the Science and Technology Research Project of Shenzhen (Nos.ZDSYS201606061530079,JCYJ20150324141711622,JCYJ20150529164656097)
文摘Electrolysis is a promising technology to improve sludge dewaterability efficiently with negligible environmental impact. To intensify the electrolytic efficiency, the effect of electrolytes(NaCl, Na_2SO_4, NaNO_3, and NaClO_4) on electrolysis pretreatment of municipal sludge and its mechanisms was investigated using Ti/PbO_2 electrodes. The electrolytes,which enhanced the production of oxidative radicals, showed a significant synergetic effect in reducing the capillary suction time(CST) of sludge. NaCl was distinguished from the other electrolytes since it formed a large amount of active chlorine species, which oxidized the sludge cells to improve the sludge dewaterability. The surface morphologies as well as the soluble proteins and polysaccharides were analyzed to unravel the underlying mechanisms of sludge dewaterability. Additionally, an economic assessment showed that NaCl addition in the electrolysis pretreatment can be a suitable technique for enhancing municipal sludge dewaterability.
基金supported by the National Key Research and Development Program of China(No.2021YFB4000101)the National Natural Science Foundation of China(No.52125102)the Fundamental Research Funds for the Central Universities(No.FRF-TP-2021–02C2).
文摘Hydrogen energy,whether in generation plants or utilization facilities,plays a decisive role in the mission to achieve net-zero greenhouse gas emissions,all to minimize pollution.The growing demand for clean energy carrier steadily accelerates the development of hydrogen production processes,and therein proton exchange membrane(PEM)water electrolysis is deemed a promising long-term strategy for hydrogen preparation and collection.This review retrospects recent developments and applications of bipolar plates(BPs)as key components in PEM fuel cells and water electrolysers.The main content includes multifaceted challenges in the R&D or fabrication of BPs and potential future trends have also been proposed.Specific details cover the BPs matrix(metallic materials and carbon composites)and the surface coating types(metal and compound coatings,carbon-based coatings,and polymer coatings),as well as the influence of flow field design for mass transport.Long-term development and feasible researches of BPs are prospected.Especially in the following aspects:(1)Structural and functional integration of components,such as material fabrication and flow field geometry optimization using 3D printing technology;(2)Introduction of environment-friendly renewable energy for hydrogen production;(3)Research on hydrogen energy reversible systems;(4)Composition optimization of surface coatings based on computational materials science and(5)systematic design expected to evolve into the next generation of BPs.
基金supported by the State Key Laboratory of Advanced Power Transmission Technology(GEIRI-SKL-2021-014)。
文摘At present,only a single modification method is adopted to improve the shortcomings of erythritol(ET)as a phase change material(PCM).Compared with a single modification method,the synergistic effect of multiple modification methods can endow ET with comprehensive performance to meet the purpose of package,supercooling reduction,and enhancement of thermal conductivity.In this work,we innovatively combine graphene oxide(GO)nanosheet modified melamine foam(MF)and polyaniline(PANI)to construct a novel ET-based PCM by blending and porous material adsorption modification.PANI as the nucleation center can enhance the crystallization rate,thereby reducing the supercooling of ET.Meanwhile,GO@MF foam can not only be used as a porous support material to encapsulate ET but also as a heat conduction reinforcement to improve heat storage and release rate.As a result,the supercooling of GO@MF/PANI@ET(GMPET)composite PCM decreases from 91.2℃ of pure ET to 57.9℃ and its thermal conductivity(1.58 W·m^(-1)·K^(-1))is about three times higher than that of pure ET(0.57 W·m^(-1)·K^(-1)).Moreover,after being placed at 140℃ for 2 h,there is almost no ET leakage in the GMPET composite PCM,and the mass loss ratio is less than 0.75%.In addition,the GMPET composite PCM displays a high melting enthalpy of about 259 J·g^(-1) and a high initial mass loss temperature of about 198℃.Even after the 200th cycling test,the phase transition temperature and the latent heat storage capacity of the GMPET PCM all remain stable.This work offers an effective and promising strategy to design ET-based composite PCM for the field of energy storage.
