Poly (vinylidene fluoride)- based polymers have a relatively large electrocaloric effect (ECE) but low thermal conductivity. In some studies, the ECE obtained from indirect measurement deviates substantially from dire...
详细信息
Poly (vinylidene fluoride)- based polymers have a relatively large electrocaloric effect (ECE) but low thermal conductivity. In some studies, the ECE obtained from indirect measurement deviates substantially from direct measurement. In this work, the ECE was investigated in composites containing the ferroelectric poly (vinylidene fluoride-trifluoro ethylene-chlorotrifluoroethylene) [P(VDF-TrFE-CTFE)] terpolymer and Al2O3 fillers. The ECE of the composites was directly measured using an infrared thermograph and indirectly obtained utilizing the Maxwell relation. The temperature changes obtained by indirect and direct measurements agree reasonably well with each other. In direct measurement, we found the temperature increase is larger than the temperature decrease at a high field or in the composites with a high concentration of nanoparticles, which can be attributed to the Joule heating effect caused by increased conductivity and dielectric loss. In the extreme case, the Joule heating dominates the temperature change, and only the temperature increase can be observed. Moreover, the temperature change is increased by more than 38% in the composite with 1.5% Al2O3 fillers. One reason for the enhanced ECE is the increase of the polar phase in terpolymer after the addition of the nanoparticles. At the same time, the thermal conductivity of the composite film is also increased by 21% due to the high thermal conductivity of Al2O3.
The negative-sequence reactive power-conductance(Q^(−)-G) droop control strategy is a conventional method to compensate for the output unbalanced voltages in an islanded ***, the conflict between unbalanced voltage co...
详细信息
The negative-sequence reactive power-conductance(Q^(−)-G) droop control strategy is a conventional method to compensate for the output unbalanced voltages in an islanded ***, the conflict between unbalanced voltage compensation and negative-sequence reactive power sharing, caused bythe impedance mismatching of distribution lines and distributedgenerators, has not been solved only by Q^(−)-G droop *** this paper, a distributed cooperative secondary unbalancedvoltage control strategy is proposed to decrease the outputvoltage unbalance factor (VUF) of each droop-controlled DG,as well as to further enhance the negative-sequence reactivepower sharing effectiveness among DGs by properly shiftingup and down the Q^(−)-G droop characteristics of each *** algorithm for adaptive VUF weight coefficient is proposedto better suppress VUF under severe imbalance ***, a negative-sequence small-signal model of an MGunder an unbalanced condition, considering the communicationdelay time of the proposed SUVC, is established to analyze thesystem’s stability and transient performance under the influenceof some critical parameters. Finally, the effectiveness of theproposed strategy is validated by the simulation results froma real-time emulator of StarSim HIL.
Iron-nitrogen-carbon single-atom catalysts(Fe-N-C SACs)are widely acknowledged for their effective oxygen reduction activity,however,their activity requires further ***,additional structural optimization is necessary ...
详细信息
Iron-nitrogen-carbon single-atom catalysts(Fe-N-C SACs)are widely acknowledged for their effective oxygen reduction activity,however,their activity requires further ***,additional structural optimization is necessary to enhance mass transport and achieve higher power density in practical ***,using ZIF-8 as a template,we synthesized yolk-shell catalysts featuring complex sites of Fe single atoms and Cu nanoclusters(y-FeCu/NC)via partial etching and liquid-phase *** synthesized y-FeCu/NC catalyst exhibits high specific surface area and mesoporous *** with the advantages of highly active sites and yolk-shell structure,the y-FeCu/NC catalyst demonstrated outstanding catalytic performance in the oxygen reduction reaction,achieving a half-wave potential(E_(1/2))of 0.97 V in 0.1 M *** a practical energy device,Zn-air battery(ZAB)assembled with y-FeCu/NC catalyst achieved a remarkable power density of 356.3 mW·cm^(-2),representing an improvement of approximately 28.5%compared to its solid FeCu/NC ***,it showcased impressive stability,surpassing all control samples.
In recent years,scientists have become increasingly concerned in recycling electronic trash,particularly waste printed circuit boards(WPCBs).Previous research has indicated that the presence of Cu impacts the pyrolysi...
详细信息
In recent years,scientists have become increasingly concerned in recycling electronic trash,particularly waste printed circuit boards(WPCBs).Previous research has indicated that the presence of Cu impacts the pyrolysis of ***,there may be errors in the experimental results,as printed circuit boards(PCBs)with copper and those without copper are produced *** this experiment,we blended copper powder with PCB nonmetallic resin powder in various ratios to create the *** apparent kinetics and pyrolysis properties of four resin powders with varying copper concentrations were compared using nonisothermal thermogravimetric analysis(TG)and thermal pyrolysis-gas chromatography mass spectrometry(Py-GC/MS).From the perspective of kinetics,the apparent activation energy of the resin powder in the pyrolysis reaction shows a rise(0.1
The development of environmentally friendly catalysts has become a top priority for acetylene ***,difficulties remain in systematic studies on the applicability of kinetic models for the industrialization of Cu-based ...
详细信息
The development of environmentally friendly catalysts has become a top priority for acetylene ***,difficulties remain in systematic studies on the applicability of kinetic models for the industrialization of Cu-based ***,a strategy involving reactor modeling,parameter estimation,and model testing is developed to evaluate the predictive ability of kinetic *** order to search for reliable and widely applicable reaction kinetic models for Cu-based catalysts,a case study is *** possible kinetic models derived from the power law,adsorption mechanism,and reaction path are sifted through collecting and testing activity data from tens of Cu-based *** optimum applicable ranges of these kinetic models are *** to the comparative analysis on their applications in various industrial scenarios,this research suggests that kinetic models derived from reaction path exhibits the best extrapolation ability and has the greatest potential for application in the scale-up design of reactors.
Remote sensing data plays an important role in natural disaster ***,with the increase of the variety and quantity of remote sensors,the problem of“knowledge barriers”arises when data users in disaster field retrieve...
详细信息
Remote sensing data plays an important role in natural disaster ***,with the increase of the variety and quantity of remote sensors,the problem of“knowledge barriers”arises when data users in disaster field retrieve remote sensing *** improve this problem,this paper proposes an ontology and rule based retrieval(ORR)method to retrieve disaster remote sensing data,and this method introduces ontology technology to express earthquake disaster and remote sensing knowledge,on this basis,and realizes the task suitability reasoning of earthquake disaster remote sensing data,mining the semantic relationship between remote sensing metadata and *** prototype system is built according to the ORR method,which is compared with the traditional method,using the ORR method to retrieve disaster remote sensing data can reduce the knowledge requirements of data users in the retrieval process and improve data retrieval efficiency.
Tetramethylammonium hydroxide(TMAH)is an important compound that utilized and released by the rapidly expanding semiconductor industry,which could hardly be removed by the conventional wastewater treatment *** a choli...
详细信息
Tetramethylammonium hydroxide(TMAH)is an important compound that utilized and released by the rapidly expanding semiconductor industry,which could hardly be removed by the conventional wastewater treatment *** a cholinergic agonist,the tetramethylammonium ion(TMA^(+))has been reported to induce toxicity to muscular and respiratory systems of mammals and human,however the toxicity on aquatic biota remains poorly *** investigated the neurotoxic effects of TMA^(+)exposure on zebrafish,based on neurobehavior tests and a series of *** inhibitions on the swimming distance of zebrafish larvae were observed when the exposure level exceeded 50 mg/L,and significant alterations on swimming path angles(straight and deflective movements)occurred even at 10 mg/*** tested neurobehavioral endpoints of zebrafish larvae were significantly positively correlated with reactive oxygen species(ROS)and malondialdehyde(MDA),significantly negatively related with the activities of antioxidant enzymes,but not significantly correlated with the level of acetylcholinesterase(AChE).Such relationship indicates that the observed neurotoxic effects on swimming behavior of zebrafish larvae is mainly driven by oxidative stress,rather than the alterations of *** the highest exposure concentration(200 mg/L),TMA^(+)evoked more severe toxicity on zebrafish juveniles,showing significantly stronger elevation on the MDA activity,and greater inhibitions on the activities of antioxidant enzymes and ACh E,suggesting juveniles were more susceptible to TMA^(+)exposure than larval zebrafish.
The star identification algorithm usually identifies stars by angular distance ***,under high dynamic conditions,the rolling shutter effect distorts the angular distances between the measured and true star positions,l...
详细信息
The star identification algorithm usually identifies stars by angular distance ***,under high dynamic conditions,the rolling shutter effect distorts the angular distances between the measured and true star positions,leading to plethoric false matches and requiring complex and time-consuming verification for star *** identification rate hinders the application of low-noise and cost-effective rolling shutter image *** this work,we first study a rolling shutter distortion model of angular distances between stars,and then propose a novel three-stage star identification algorithm to identify distorted star images captured by the rolling shutter star *** first stage uses a modified grid algorithm with adaptive error tolerance and an expanded pattern database to efficiently eliminate spurious *** second stage performs angular velocity estimation based on Hough transform to verify the matches that follow the same distortion *** third stage applies a rolling shutter error correction method for further *** the simulation and night sky image test demonstrate the effectiveness and efficiency of our algorithm under high dynamic *** accuracy of angular velocity estimation method by Hough transform is evaluated and the root mean square error is below 0.5(°)/*** algorithm achieves a 95.7% identification rate at an angular velocity of 10(°)/s,which is much higher than traditional algorithms.
Income inequality is widespread in human society and has important implications for human ***’s perception of the environment bridges income inequality and individual behavioral *** research suggests that social inco...
详细信息
Income inequality is widespread in human society and has important implications for human ***’s perception of the environment bridges income inequality and individual behavioral *** research suggests that social income inequality is usually biased,either overestimated or ***,such phenomena have not been fully explored with quantitive prove,especially in the working environment based on performance data of actual *** fact,the correct perception of people is the basis of a fair environment for their production ***,the perception bias may weaken the adaptability and competitiveness of a company in the *** paper first confirms the prevalence of individual perception bias of income inequality within the working environment based on actual production *** results show that people tend to underestimate income inequity around them,and this underestimation grows with the real unfairness of the working ***,this paper proposes a network generation-based framework with a three-layer structure to correct perception bias using a cooperative network reengineering *** the framework,a homophily-based generative network model is proposed as the key *** simulation results show that our proposed framework effectively reduces individuals’perception bias of income inequality.
Capacitors are widely used in pulsed magnet power supplies to reduce ripple voltage,store energy,and decrease power *** this study,DC-link capacitors in pulsed power supplies were *** deriving an analytical method for...
详细信息
Capacitors are widely used in pulsed magnet power supplies to reduce ripple voltage,store energy,and decrease power *** this study,DC-link capacitors in pulsed power supplies were *** deriving an analytical method for the capacitor current on the H-bridge topology side,the root-mean-square value of the capacitor current was calculated,which helps in selecting the DC-link *** proposed method solves this problem quickly and with high *** current reconstruction of the DC-link capacitor is proposed to avoid structural damage in the capacitor’s current measurement,and the capacitor’s hotspot temperature and temperature rise are calculated using the FFT *** test results showed that the error between the calculated and measured temperature increases was within 1.5℃.Finally,the lifetime of DC-link capacitors was predicted based on Monte Carlo *** proposed method can evaluate the reliability of DC-link capacitors in a non-isolated switching pulsed power supply for accelerators and is also applicable to film capacitors.
暂无评论