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可用于地热和油气井眼电池的Li-Mg-B合金/LiNO3-KNO3-KNO2-Ca（NO3）2/MnO2体系的表征

Anovelquaternaryeutectic,LiNO3-KNO3-KNO2-Ca(NO3)2,isdevelopedforthepotentialuseingeothermalandoil/gasboreholebattery.Thechemicalcompatibilityofthematerialisexaminedbythesimultaneousthermogravimetricanalysisanddifferentialthermalanalysis.TheMnO2cathodespresentinsinglecellswithLi-Mg-Balloyanodesarecharacterizedusingtheeutecticelectrolyteat150-300 °Candacurrentdensityof10-30 mA cm?#xA0;2.Thedischargecapacityofthebatteryisnotaffectedbydischargerate;however,itissignificantlyaffectedbytheoperatingtemperature.

外文数据库

合成参数对锂离子电池用LiFePO4物理化学和电化学性能的影响

LiFePO4(LFP)hasbeendevelopedasacathodeforlithiumionbatteries(LIBs)bysolutioncombustionmethod.Thepresentworkincludeseffectoffuel,residualcarbonandgrapheneoxideonthephasepurityandelectrochemicalperformanceofcombustionsynthesizedLiFePO4.AsrevealedinXRD,singlephaseLiFePO4isobtainedinglycineassistedcombustion(G-LFP)anditdelivers97?mA?h/gdischargecapacity,whichishigherthanureaassistedcombustion(U-LFP).Further,theG-LFPwascalcinedfordifferentlengthsoftime(4,5and7?h).Theamountofin-situcarbonisobservedtodecreasefrom2.57to1.40%andspecificcapacityincreasesfrom97(4?h)to106?mA?h/g(7?h).Thecompositeswith4?wt%GOwereformedandtheyshowenhancedelectrochemicalperformance.5LFP/GOdeliversdischargecapacityof164?mA?h/gat0.1C,whichis96%ofitstheoreticalcapacity.

外文数据库

澳大利亚和新西兰医院外心脏停止停止(OHCA)的流行病:Aus-ROC OHCA 爆发的结果

外文数据库

无人机使用的前景和挑战

外文数据库

带扰流器的并联风冷电池热管理系统的优化设计

Inthisstudy,anovelcoolingstrategybasedonsettingspoilersintheairflowdistributionplenumofaparallelair-coolingmodelwasproposedtoimprovethecoolingperformanceofabatterycoolingsystem.Incombinationwiththecomputationalfluiddynamics(CFD)method,theeffectsofthenumberandpositionofspoilersonthethermalbehaviorsofabatterythermalmanagementsystem(BTMS)wereexplored.Theresultsdemonstratedthatthenumberandpositionofspoilersexhibitedasubstantialinfluenceontheheatdissipationperformanceofthebatterypack.Incomparisonwiththeoriginalmodel,themaximumtemperatureandmaximumtemperaturedifferenceofthebestcasewithspoilerswerereducedby1.86?Kand2.51?K,respectively.Additionally,theeffectsoftheangleandheightofthespoilersonthecoolingperformanceofthebatterypackwereanalyzedandoptimizedusingthe5-spoilermodel.Theresultsrevealedthattheangleofthespoilershadasignificanteffectonthecoolingperformance.Whentheanglewas80°,themaximumtemperatureandmaximumtemperaturedifferencewerereducedby2.11?Kand2.77?K,respectively.Moreover,appropriatelyadjustingtheheightofthespoilerscouldimprovethecoolingperformance.Furthermore,thewidthofthecoolingchannelalsohadaneffectonthecoolingperformance,whichwasdiscussed.Aspoilerwasaddedinthefirstcoolingchanneltofurtherimprovethecoolingperformanceofthebatterypack.Theresultsdemonstratedthatthemaximumtemperatureandmaximumtemperaturedifferencewerereducedby3.39?K(6.66%)and5.87?K(94.24%),respectively.Finally,theinfluencesofthelengthandheightofthemanifoldswereinvestigated.Thesimulationanalysisresultsindicatedthattheproposedthermalmanagementmethodcouldeffectivelyimprovethecoolingperformanceoftheair-coolingsystem."

外文数据库

用于高级锂硫阴极的掺铝ZnO颗粒修饰的桑椹状中空碳簇

Toimprovetheelectrochemicalperformancesoflithium-sulfur(Li-S)batteriesandextendtheircyclelife,amulberry-likeAl-dopedZnO(AZO)particlesdecoratingcarbonclustercomposite(C@AZOcluster)issynthesizedastheLi-Scathodematerial.TheC@AZO/Scomposite,withthesulfurcontentof70?wt%andthesulfurmassloadingof2.2?mg?cm?2,deliversahighinitialspecificcapacityof974.2?mAhg?1atthecurrentdensityof0.5C(1C?=?1675?mAhg?1)andalowcapacitydecayof0.12%percycleover300cycles.Inthiscomposite,theinterconnectedprimarycarbonspheresdecoratedbyconductiveAZOparticlesprovideafastchargetransmissionnetworkwhichcouldgreatlyenhancethereactionkineticsandrateperformanceofLi-Sbatteries.Meanwhile,theintegratedarchitectureofcarbonclusterandthepolaritybroughtbyAZOcouldeffectivelyreducethedissolutionofpolysulfidestoimprovethecyclestability.

外文数据库

无人机集群分布式集群控制策略

To ensure the information security of UAV groups, maximize the detection range of the UAV group and minimize the communication range, this paper improves Olfati–Saber’s flocking algorithm using virtual leader and integrates the multiple UAVs with real environment. The improved swarm control algorithm can help to make all agents accurately track the speed of virtual leaders. Then, we introduce the conception of virtual communication circle to control the communication power of each UAV, and the moving function of the target position is improved to meet the limited conditions of given communication distance, to ensure the non-collision and stable communication of the UAV during the moving process. All UAVs in the group system will keep converging, avoiding collision and the speed is the same as that of the virtual pilot. Therefore, multiple UAVs can track the virtual pilot for cluster flight and a distributed cooperative control strategy can be acquired. The simulation results show that the strategy proposed in this paper makes a better communication performance among UAVs in real time, and the UAV groups achieve the information more timely, which is proved to be an effective way to ensure the security communication among multiple UAVs."

外文数据库

推力矢量飞翼的激进机动：地平线后退方法

Deals with the control of a thrust vectored flying wing known as the ducted fan, developed at California Institute of Technology. The experiment was developed to serve as a testbed for nonlinear control design. In an earlier paper, the authors reported simulation results based on a simplified (no aerodynamics involved) planar model of the ducted fan around hover position. We report on the modeling and simulation of the ducted fan in forward flight, where aerodynamic forces and moments can no longer be ignored. A receding horizon scheme is developed to generate trajectories for the forward flight model. Using a more simplified version of the model, some aggressive trajectories are generated. These trajectories are then used as a reference in the receding horizon scheme, and morphed into the trajectories of the full model. Simulation results depict the capabilities of the ducted fan as well as this methodology in performing aggressive maneuvers.

外文数据库

电化学-机械能转换

外文数据库

使用无人机系统在传统地下核爆炸试验场收集高光谱图像和数字高程模型

Hyperspectral and multispectral imagers have been developed and deployed on satellite and manned aerial platforms for decades and have been used to produce spectrally resolved reflectance and other radiometric products. Similarly, light detection and ranging, or LIDAR, systems are regularly deployed from manned aerial platforms to produce a variety of products, including digital elevation models. While both types of systems have demonstrated impressive capabilities from these conventional platforms, for some applications it is desirable to have higher spatial resolution and more deployment flexibility than satellite or manned aerial platforms can offer. Commercially available unmanned aerial systems, or UAS, have recently emerged as an alternative platform for deploying optical imaging and detection systems, including spectral imagers and high resolution cameras. By enabling deployments in rugged terrain, collections at low altitudes, and flight durations of several hours, UAS offer the opportunity to obtain high spatial resolution products over multiple square kilometers in remote locations. Taking advantage of this emerging capability, our team recently deployed a commercial UAS to collect hyperspectral imagery, RGB imagery, and photogrammetry products at a legacy underground nuclear explosion test site and its surrounds. Ground based point spectrometer data collected over the same area serves as ground truth for the airborne results. The collected data is being used to map the site and evaluate the utility of optical remote sensing techniques for measuring signatures of interest, such as the mineralogy, anthropogenic objects, and vegetative health. This work will overview our test campaign, our results to date, and our plans for future work.

外文数据库

单晶UA的比热和等温磁热效应

Two complementary quantities, the specific heat at a constant magnetic field (C_B) and the isothermal magnetocaloric coefficient (M_T), have been investigated for a UAs single crystal in the range of T=20鈥?60K and B=0-13T. Both measurements have been performed by a method using a miniature heat-flux meter as a sample support. All phase transitions between paramagnetic phase, two types of antiferromagnetic (single-k type I and double-k type IA) phases, and two types of ferrimagnetic (single-k and double-k) phases have been found to be of first order, and their entropy jumps have been estimated. It was directly shown by magnetocaloric measurements that the entropy jump at a phase transition upon increasing magnetic field may be either positive or negative, depending on the slope of the phase transition line. A three-dimensional plot of the singular part of the magnetic entropy was constructed using both C_B and M_T data. Peculiar features, such as a precursor anomaly occurring about 鈭? T before the paramagnetic/single-k ferrimagnetic transition (possibly related to the so-called Lifshitz instability) and a first-order transition without any latent heat occurring at the inversion point on the double-k type IA/ferri-2k phase transition line, bearing some analogy with the p-T phase diagram of ³He, are discussed.

外文数据库

以多壁碳纳米管为导电添加剂提高Li/CF x 电池的放电性能

ThedischargeperformanceofLi/CFx(x = 1)batteryisimprovedbyusingmulti-walledcarbonnanotubes(MWCNTs)asanalternativeconductiveadditive.Comparedwiththebatteryusingacetyleneblackasconductiveadditiveatthesameamount,theLi/CFxbatteryusingMWCNTsasconductiveadditivehashigherspecificcapacityandenergydensityaswellassmoothervoltageplateau,especiallyathigherdischargerate.Thespecificcapacityatdischargerateof1 Cisimprovedbynearly26%whenMWCNTsareemployedasconductiveadditive.Meanwhile,itisalsofoundthatthedischargeperformanceisabletobetunedbytheamountofMWCNTsandthebatterycontainingmoreMWCNTsisfavorabletobedischargedathigherrates.ThespecificcapacityofLi/CFxbatterywith11.09 wt.%MWCNTsisapproximately712 mAh g−1atthedischargerateof1 C.Itisproposedthattheformedthree-dimensionalnetworksofMWCNTsincathode,whichenlargesthecontactareaofinterphaseandfacilitateselectronsdelivery,acceleratestheratesoflithiumiondiffusionintothefluorinatedlayersandelectronstransportincathodeatthesametime,whichimprovesthedischargeperformanceofLi/CFxbatterysubsequently,especiallyathigherrates.

外文数据库

聚乙酸乙烯酯用作制备锂离子电池用LiFePO4基复合阴极的粘合剂

Thispaperdescribesamethodforthepreparationofcompositecathodesforlithiumion-batteriesbyusingpolyvinylacetate(PVAc)asabinder.PVAcisanon-fluorinatedwaterdispersiblepolymercommonlyusedinalargenumberofindustrialapplications.Themainadvantagesforusingofthispolymerarerelatedtoitslowcostandnegligibletoxicity.Furthermore,sincethePVAciswaterprocessable,itsuseallowstoreplacetheorganicsolvent,employedtodissolvethefluorinatedpolymernormallyusedasabinderinlithiumbatterytechnology,withwater.Insuchawayitispossibletodecreasethehazardousnessofthepreparationprocessaswellastheproductioncostsoftheelectrodes.Inthepaperthepreparation,characterizationandelectrochemicalperformanceofaLiFePO4electrodebasedonPVAcasthebinderisdescribed.Furthermore,toassesstheeffectofthePVAcbinderontheelectrodeproperties,itsperformanceiscomparedtothatofaconventionalelectrodeemployingPVdF-HFPasabinder.

外文数据库

LiNi0.5Mn1.5O4多孔纳米棒作为高倍率长寿命锂离子电池阴极

Spinel-typeLiNi0.5Mn1.5O4porousnanorodsassembledwithnanoparticleshavebeenpreparedandinvestigatedashigh-rateandlong-lifecathodematerialsforrechargeablelithium-ionbatteries.One-dimensionalporousnanostructuresofLiNi0.5Mn1.5O4withorderedP4332phasewereobtainedthroughsolid-stateLiandNiimplantationofporousMn2O3nanorodsthatresultedfromthermaldecompositionofthechain-likeMnC2O4precursor.ThefabricatedLiNi0.5Mn1.5O4deliveredspecificcapacitiesof140and109mAhg鈥?at1and20Crates,respectively.Ata5Ccyclingrate,acapacityretentionof91%wassustainedafter500cycles,withextremelylowcapacityfade(<1%)duringtheinitial300cycles.Theremarkableperformancewasattributedtotheporous1DnanostructuresthatcanaccommodatestrainrelaxationbyslippageatthesubunitswallboundariesandprovideshortLi-iondiffusiondistancealongtheconfineddimension.Keywords:LiNi0.5Mn1.5O4;spinel;porousstructure;nanomaterials;Li-ionbattery

外文数据库

持续无人机配送物流：MILP 公式和高效启发式

The high efficiency, flexibility and low cost of Unmanned Aerial Vehicles (UAVs) present huge application opportunities in various industries. Among those various applications, we focus herein on the use of UAVs in delivery logistics. The UAV logistics system has some fundamental characteristics that distinguish it from the usual ground logistics such as limited flight time, loadable capacity, effect of cargo weight on flight ability, and others. To handle the above issues, we propose a Mixed Integer Linear Programming (MILP) formulation for derivation of persistent UAV delivery schedules. To address the computational issues, a Receding Horizon Task Assignment (RHTA) heuristic is developed and tested with numerical examples for island-area delivery.

外文数据库

溶解蒸发法制备全固态锂离子电池用Li7P3S11微晶玻璃电解质

Design/fabricationofsolidstateelectrolyteswithhighionicconductivityisofgreatimportancetodevelopnext-generationLiionbatteries.Inthiswork,theLi7P3S11glass-ceramicelectrolyteissuccessfullysynthesizedbydissolution-evaporationapproach.ThesolventeffectontheelectrochemicalperformanceofLi7P3S11isinvestigatedbyelectrochemicalimpedancespectroscopyandchronoamperometrytests.TheLi7P3S11electrolytepreparedbyasolutionofacetonitrilehasahighionicconductivityof9.7 × 10−4 S cm−1at298 Kandalowactivationenergyof31.2 kJ mol−1.Impressively,awideandstableelectrochemicalwindowupto5 V(vs.Li/Li+)isdemonstratedbetweenthesolidelectrolyteandlithiumelectrode.Thedevelopeddissolution-evaporationapproachshowsgoodindustrialprospectduetoitsadvantagesofenergyconservationandhighefficiency.

外文数据库

用于锂离子电池紧急关闭的由二醇和二胺组成的腐蚀性电解质毒物和多功能流体

Electrolytepoisonscomprisedofdiolsanddiaminesareinvestigatedfortheintendedfunctionofexacerbatinginternalresistanceinlithium-ionbatteriesuponshortcircuitfailure,toquicklyarrestuncontrolledjouleheatgenerationintheearlieststages.ThecompetingdynamicsofpowerfulshortcircuitcurrentsandelectrolytepoisoninginteractionsareevaluatedviasimultaneousnailpenetrationandpoisoninjectionofLIR2450formatLiCoO2/graphite120mAhcoincells.Toforciblyincreaseelectrolyteimpedance,diolsservetohindercharge-carryingionmobilitybyraisingsolutionviscosity,whilediaminesdisruptsolventpermittivitybyrapidlypolymerizingtheethylenecarbonatesolvent.Diaminesdemonstrategreatpotency,andaresuitableforintegrationintobatterycellswithinchemically-inert,breakablecontainers,riggedforreleaseuponmechanicalactivation.Mixturesof1,2-ethanedioland1,2-ethanediamineshowsynergisticpoisoningeffects,decreasingpeaktemperatureaccruedby70%whenintroducedsimultaneouslyuponnailpenetration.Withtheinnatepresenceandabundanceofdiolsanddiaminesinelectricvehicleheatexchangers,theymaybeemployedformultifunctionalapplications.

外文数据库

用于二次电池应用的非水体系的电化学表征

外文数据库

镍氢电池专家系统

外文数据库

仿生自主水下航行器阻力与推进性能研究

The carp-like geometry was obtained by measurements of two carps. The swimming motion equation was fitted by the CCD image of a carp swimming in a water tunnel. Then a two-dimensional RANS (Reynolds averaged Navier-Stokes solver) code was applied to solve the flow field caused by the swimming motion of carp-like geometry. The calculated results show that the lateral velocity induces a high pressure at the convex part and low pressure at the concave part of the flexible body and produces the thrust. Also, the lateral velocity convects out the vorticity from the inner region to the outer region of the boundary layer and causes laminarization of the boundary layer.

外文数据库

n维踢球转子的经典动力学和量子动力学

The classical and quantum dynamics for an n-dimensional generalization of the kicked planar (n=1) rotator in an additional effective centrifugal potential. Therefore, typical phenomena like the diffusion in classical phase space are similar to that of the one-dimensional model. For the quantum dynamics such a result is not expected as in this case the evolution does depend in a very complicated way on the number n of degrees of freedom. In the limit n --> infinity we find the free undistrubed quantum motion. For finite values of n (1<=n<=26) we study numerically the quantum dynamics. Here, we always find localization independent of the actual number of degrees of freedom.

外文数据库

基于 BIM 和物理引擎的 UGV 室内环境全局路径规划

This paper proposes a global path planning (GPP) system based on building information modeling (BIM) and physics engine for unmanned ground vehicles (UGVs) operations in indoor environments. Firstly, UGV configuration is integrated into BIM as a knowledge base of GPP system by customized IFC structure, with which a multi-layer map generation method is proposed with improved logic and efficiency. Secondly, a UGV-centric A* path planning algorithm is designed by considering UGV's properties, including mobility-based primitive expansion, geometry-based collision checking, mobility-based cost setting, and mobility-based analytical expansion. Finally, a reliable trajectory generation method is developed based on physics engine, followed with a novel spatiotemporal coordination method for efficient collision avoidance. The whole GPP system is validated in a representative university building floor and a common inspection UGV. It is demonstrated that UGV-integrated BIM improves the resources interoperability for the whole system, and the map components are clarified clearly for efficient generation and maintenance. Besides, the UGV-centric A* performs a 100% success rate in congested environments where traditional A* always fail. It can even reduce almost 50% of the trajectory time and steering jerk in open scenarios than traditional A*, but still with an acceptable computation speed (less than 0.6?s). Finally, trajectory coordination saves 50% of path traveling time compared with the general queue method.

外文数据库

水空两栖可变翼无人机机械系统设计

外文数据库

在转换定向表层下对多个未充分激活的AVV进行分散的有限时间、无速度、无速度、稳健的形成控制

This paper proposes a distributed finite-time velocity-free robust formation control scheme for multiple underactuated autonomous underwater vehicles (AUVs) under switching directed topologies in the presence of uncertain dynamics and unknown time-varying external disturbances. Here, a novel finite-time velocity observer is created for each AUV to estimate its neighbors’ velocities within a finite time so that only its neighbors’ positions need to be transmitted, which reduces the communication burden between AUVs. Then, a super-twisting extended state observer is constructed for each AUV to estimate its total disturbances lumped by the uncertain dynamics and the unknown time-varying external disturbances, whose estimation errors can converge to zero within a finite time. Further, a distributed finite-time velocity-free robust formation control law is proposed incorporating the above into the nonsingular terminal sliding mode technique. Theoretical analysis and simulation results indicate that the proposed formation control law can make the multiple AUVs achieve the desired formation pattern while guaranteeing the formation errors converge to zero within a finite time.

外文数据库

对自主水下航行器的化学传感器数据进行自动分类

Autonomous underwater vehicles (AUVs) are commonly used to support oceanographic science by providing water-column mapping, seafloor bathymetric and photographic survey, and deep-sea exploration capabilities. In practice, the mapping activities carried out by AUVs consist of flying either pre-programmed tracklines (most propeller-driven AUVs), or else reporting data to human operators at regular intervals that permit retasking (typical for month-long underwater glider deployments). AUVs equipped with the ability to reason about scientific objectives in real time could significantly increase the value of individual deployments by enabling sampling efforts to be focused on targets or areas identified autonomously or semi-autonomously as scientifically interesting [1]. In this paper, we focus on AUV autonomy as it pertains to water-column sensing and argue that the classification of water-column sensor data represents an important enabling capability. We demonstrate practical, semi-supervised classification of water-column sensor data using a particular Bayesian, non-parametric clustering method, the Variational Dirichlet Process, combined with operator-supplied semantic labeling. The method is applied to the detection of a deep subsea hydrocarbon plume using data collected by theWoods Hole Oceanographic's Sentry AUV during an expedition to the Gulf of Mexico following the Deepwater Horizon blowout disaster.

外文数据库

Co和CoO对Ni/MH动力电池Ni(OH) 2 电极性能影响的差异

Theeffectsofmetalliccobalt(Co)andcobaltmonoxide(CoO),asadditivesinpositiveelectrodes,ontheelectrochemicalperformanceofnickel/metalhydride(Ni/MH)powerbatteriesarestudied.CommercialCoandCoOarechargedat50 °Cin6 MKOHsolution.Theoxidationmechanismofcobaltmaterialsisinvestigatedbyobservingstructuralandmorphologicalevolutionsduringcharging.ApureCo3O4-typephaseisformedwhenthestartingmaterialisCoO.WhenCoisused,acobaltoxyhydroxide(CoOOH)phaseispresent,togetherwithatricobalttetroxide(Co3O4)phase.Inbothcases,thecobaltconcentrationintheelectrolytedecreasesduringoxidation.Thefinalproductisdependentonthesolubilityofcobaltandthekineticsofthereactionthatconsumescobalttetrahydroxide[Co(OH)4]2−.ThehighlycompactCoOOHphase,whichworkswellbetweenthenickelfoamframeandnickelhydroxide[Ni(OH)2]particles,enhancesthepowerperformanceofNi/MHpowerbattery.TheCo3O4phase,whichworkswellinconnectingNi(OH)2particles,improvesthecapacitiveperformanceofNi/MHpowerbattery.

外文数据库

Yangian对偶与有理R矩阵

Studying the algebraic structure of the double ${\cal D}Y(g)$ of the yangian $Y(g)$ we present the triangular decomposition of ${\cal D}Y(g)$ and a factorization for the canonical pairing of the yangian with its dual inside ${\cal D}Y(g)$. As a consequence we obtain an explicit formula for the universal R-matrix $R$ of ${\cal D}Y(g)$ and demonstrate how it works in evaluation representations of $Y(sl_2)$. We interprete one-dimensional factor arising in concrete representations of $R$ as bilinear form on highest weight polynomials of irreducible representations of $Y(g)$ and express this form in terms of {\it gamma-functions}.

外文数据库

小型固定翼无人驾驶航空器的双向系统识别和跟踪跟踪控制

An approach for obtaining dynamically feasible reference trajectories and feedback controllers for a small unmanned aerial vehicle (UAV) based on an aerodynamic model derived from flight tests is presented. The modeling method utilizes stepwise multiple regression to determine relevant explanatory terms for the aerodynamic coefficients. A dynamically feasible trajectory is then obtained through the solution of an optimal control problem using pseudospectral optimal control software. Discrete-time feedback controllers are further designed to regulate the vehicle along the desired reference trajectory. Simulations in a realistic operational environment as well as flight testing of the feedback controllers on the aircraft platform demonstrate the capabilities of the approach.

外文数据库

WN1626+5153：来自WENSS调查的巨型射电星系

An FRII radio source with an angular extension of 18.4 arcminutes has been discovered in the Westerbork Northern Sky Survey that is being carried out at 325 MHz. This source is identified with Mrk 1498 at $z=0.056$ indicating that its projected extension is 1.6 \h50\ Mpc. The optical spectrum of Mrk 1498 has the typical emission lines of a narrow line radio galaxy; H$\alpha$ is the only permitted line that has a faint broad component. The discovery shows that the good sensitivity of WENSS at low frequencies to low surface brightness features at scales of a few minutes, is uniquely suited to provide well defined and relatively large samples of giant radio galaxies. The future definition of such samples will be important for our understanding of giant radio galaxies.

外文数据库

使用高能X射线康普顿散射对商用锂离子可充电电池的锂浓度进行操作定量

ComptonscatteringisoneofthemostpromisingprobesforquantitatingLiunderin?operandoconditions,sincehigh-energyX-rays,whichhavehighpenetrationpower,areusedastheincidentbeamandtheCompton-scatteredenergyspectrumhasspecificline-shapesforeachelement.Anin?operandoquantitationmethodtodeterminetheLicompositioninelectrodeshasbeendevelopedbyusingline-shape(S-parameter)analysisoftheCompton-scatteredenergyspectrum.Inthisstudy,S-parameteranalysishasbeenappliedtoacommercialcoincellLi-ionrechargeablebatteryandthevariationoftheS-parametersduringthecharge/dischargecycleatthepositiveandnegativeelectrodeshasbeenobtained.ByusingcalibrationcurvesforLicompositionintheelectrodes,thechangeinLicompositionofthepositiveandnegativeelectrodeshasbeendeterminedusingtheS-parameterssimultaneously.

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黑洞上球形吸积的时间相关分析

Results are presented from a time--dependent, numerical investigation of spherical accretion onto black holes, within the framework of relativistic radiation hydrodynamics. We have studied the stability of self--consistent, stationary solutions of black hole accretion with respect to thermal and radiative perturbations and also the non--linear evolution of unstable, high temperature models, heated by the hard radiation produced by the accretion flow itself in the inner region near to the horizon. In some cases, a hydrodynamic shock forms at around $10^3$--$10^4$ Schwarzschild radii, where Compton heating exceeds radiative cooling. The calculations were made using a suitably designed radiation hydrodynamics code, in which radiative transfer is handled by means of the PSTF moment formalism and which contains an original treatment of the radiation temperature equation.

外文数据库

大规格磷酸铁锂电池热失控及着火行为的实验研究

Withtheincreaseoflarge-scalelithiumionbatteries(LIBs),thethermalrunaway(TR)andfirebehaviorsarebecomingsignificantissues.Inthispaper,aseriesofthermalabusetestswereconductedon243AhLIBsintwoconditionsusinganinsitucalorimeter.Oneis“ignitedtest(case1)”andtheotherisinvolvingin“unignitedtest(case2)”.Theflammablesubstanceswereignitedbyanigniteratthesafetyventing(SV)undercase1andtheburningbehaviorsofLIBswereinvestigatedcomprehensivelyfromtheaspectoftemperaturecharacteristics,voltage,massloss,heatreleaserate(HRR),totalheatrelease(THR)andgasrelease.Incase2,theventingbehaviorswerecharacterizedandtheeffectsofSOCandflameontheTRprocessofindividualcellhavealsobeeninvestigated.TheHRRandTHRcanreach88.6?kWand19530.6?kJ,respectively.Areal-scalescenarioof50?m3isusedtoassessthegastoxicity.TheCOandHFhavelargertoxicitythanothergases.TheresultsindicatethatfirehazardsofLIBsincreasewiththeSOC.Thecharacteristictemperatureisdeterminedbytheinnerreactions,andtheflamingcombustionacceleratestheTRprogress.TherelationshipbetweenTRandfirebehaviorsisrevealedfromtheaspectsofelectrolytevaporization,gasgenerationandventing.ItisanalyzedthatthefastexothermicprocessesduringTRarethemaincausesthatleadtothejetfire.SeveralproposalsareadvancedtoimprovethesafetyapplicationofLIBs.

外文数据库

锂空气电池中用于高耐久性锂金属阳极的自适应成形双相界面

Li–airbatteryexhibitsapromisingprospectasenergyconversionandstoragedevicesduetoitsultrahightheoreticalenergydensity.However,lithiummetalasanodeishamperedduetotheintricateambientelectrochemicalenvironmentespeciallyintheopenandsemi-openbatteries.Hereinastrategythatinsitufabricatingdual-phaseprotectiveinterfaceisproposedtoimprovethedurabilityoflithiummetalanodeforLi–airbattery.Athinfilmgeneratesandcontactsintimatelyonthesurfaceviafloatinglithiumfoilonasilanemixedsolution,thentheinorganicparticlesLi6(Si2O7)appearadaptivelyandembedsintheSi-O-Sipolymerduringtheinitiallithiumplating/strippingprocess.Thein-situintegrationofinorganicparticlesandpolymermatrixenabletheinterfacetopossessadensemorphology,highmechanicalrigidity,highlithiumionsconductivityandhighinterfaceenergy,defendingtheattackofmoistureandO2?andfurthermorekeepingahomogeneousLi+depositionevenathighlocalcurrentdensity.Asaresult,anoutstandingimprovementonthereversibilityofLi–airbatteryisachievedwith180cyclesatahighcurrentdensityof1000??mA??g?1andcapacitycontrolof1000??mAhg?1inairatmosphere(O2:N2:H2O??=??4:16:3)."

外文数据库

与多辆USV和基于Swarm情报的无人驾驶飞行器合作防御

Modern defense systems are developing towards systematization, intellectualization and automation, which include the collaborative defense system on the sea between multiple unmanned surface vehicles (USVs) and unmanned aerial vehicles (UAVs). UAVs can fly in high altitude and collect marine environment information on patrolling. Furthermore, UAVs can plan defense paths for USVs to intercept intruders with full-assignment or reassignment strategies aiming at maximum overall benefits. Thus, we propose dynamic overlay reconnaissance algorithm based on genetic idea (GI-DORA) to solve the problem of multi-UAV multi-station reconnaissance. Moreover, we develop continuous particle swarm optimization based on obstacle dimension (OD-CPSO) to optimize defense path of USVs to intercept intruders. In addition, under the designed defense constraints, we propose dispersed particle swarm optimization based on mutation and crossover (MC-DPSO) and real-time batch assignment algorithm (RTBA) in emergency for formulating combat defense mission assignment strategy in different scenarios. Finally, we illustrate the feasibility and effectiveness of the proposed methods.

外文数据库

锂离子电池在燃烧试验中的特性

•Firetestsoncommerciallithium–ironphosphatecellsandlaptopbatterypacks.•Heatreleaserate(HRR)measured,higherstateofcharge(SOC)giveshigherHRRpeaks.•ToxicemissionsofHFandPOF3(notdetected)quantitativelymeasured.•HighertotalHFemissionforlowerSOCvalues.

外文数据库

一次性制备用于能源应用的石墨烯基纳米杂化材料的通用方法

Crumpledgrapheneoxide(GO)/grapheneisanewtypeofcarbonnanostructurethathasdrawngrowingattentionduetoitsthree-dimensionalopenstructureandexcellentstabilityinanaqueoussolution.Herewereportageneralandone-stepapproachtoproducecrumpledgraphene(CG)鈥搉anocrystalhybrids,whichareproducedbydirectaerosolizationofaGOsuspensionmixedwithprecursorions.NanocrystalsspontaneouslygrowfromprecursorionsandassembleonbothexternalandinternalsurfacesofCGballsduringthesolventevaporationandGOcrumplingprocess.Moreimportantly,CG鈥搉anocrystalhybridscanbedirectlydepositedontovariouscurrent-collectingsubstrates,enablingtheirtremendouspotentialforenergyapplications.Asaproofofconcept,wedemonstratetheuseofhybridelectrodesofCG鈥揗n3O4andCG鈥揝nO2inanelectrochemicalsupercapacitorandalithium-ionbattery,respectively.Theperformanceoftheresultingcapacitor/batteryisattractiveandoutperformsconventionalflatgraphene-basedhybriddevices.Thisstudyprovidesanewandfacileroutetofabricatinghigh-performancehybridCG鈥搉anocrystalelectrodesforvariousenergysystems.Keywords:crumpledgraphene;nanocrystal;nanohybrid;aerosolization;electrochemicalsupercapacitor;lithium-ionbattery

外文数据库

存在风场时最小电池消耗的无人机轨迹伪谱优化

This paper is concerned with trajectory optimisation for an unmanned aerial vehicle in the presence of a wind field. The problem consists of minimising the consumption of battery to reach a target region while keeping a constant altitude. The vehicle is modelled as a point mass, which can be controlled by changing the magnitude and orientation of the force vector provided by the propulsion system. A numerical solution for the resulting nonlinear optimisation problem is obtained by using a pseudospectral solver. Simulation scenarios with different wind fields are presented for illustration. The resulting solutions exploit regions of favourable tailwinds in order to reduce battery consumption, while enforcing attitude angle constraints.

外文数据库

低带宽条件下与自主水下航行器的协作测绘

This paper presents a survey and mapping strategy developed and simulated at the University of Idaho (UI). The UI mapping strategy utilizes low-bandwidth acoustic communication to populate and maintain a distributed representation of the search area among a small fleet of autonomous underwater vehicles. Using available acoustic communications, the individual vehicles create a multi-level representation of the search area. A low-resolution map contains information about the positions of other vehicles in the fleet, estimated coverage of the search area, low-resolution mine-like object (MLO) locations, and potentially dangerous areas for the autonomous underwater vehicles (AUVs). A high-resolution map contains significantly more accurate location estimates for MLO contacts. Maintenance of such a map of the search area enables certain advanced behaviors by the fleet of AUVs, as well as ensuring redundancy in the storage of important information; this redundancy provides assurance that, even if a vehicle were to be lost during a mission, much of the data obtained by that AUV would still be recoverable. These improvements allow for the more efficient and reliable conduct of autonomous mine countermeasure (MCM) missions.

外文数据库

锂金属在锂负极表面的电沉积，模拟研究：动力学蒙特卡罗嵌入原子法

InthispaperbyusingKineticMonteCarlo(KMC)methodalongwiththeembeddedatommethod(EAM),theelectrodepositionoflithiummetalonthelithiumanodesurfaceinlithium-ionbatteries(LIBs)isinvestigated.Thepurposeofthisresearchistodemonstratehowtheoperatingcondition,ofaLIB,suchastemperature,electrolyteconcentration,andvoltagechangeacrosstheLi-anodesurfaceandelectrolytemayaffecttheLi-anodebehaviorduetodiffusion,deposition,crystalorientation,anddoublelayerformationbyLi-atomontheanodesurface.Analysesoftheobtainedresultsandtheiragreementwiththeavailableexperimentaldataconfirmthevalidityofemployedsimulationprocedureandindicatethatsurfacemorphologyisinfluencedsignificantlybysurfacediffusionwhichisgovernedbyhopping,bulk-atomexchange,stepedgeandgrainboundarymechanisms,andconsequently,theperformanceoftheLIBwouldbecontrolledbythecrystallinestructureoftheLi-anode.ConsideringtheoverallresultsrevealsthatbyadjustingtheLIBoperatingconditionandmodifyingitsanodesurfacechemistry,itispossibletoachieveasmoothcrystalstructureontheLi-anodesurfaceandpreventtheformationofundesirabledepositssuchasLi-dendritestructures,andtherebypromotetheefficiencyoftheLIB.

外文数据库

具有宽禁带NaTi2(PO4)3纳米晶电解质的新型固态钠离子电池

NaTi2(PO4)3(NTP),awell-knownanodematerial,couldbeusedasasolidwide-bandgapelectrolyte.Herein,anovelsolid-statesodium-ionbattery(SSIB)withthethicknessofelectrolyteuptothe...

外文数据库

Gieseker和Uhlenbeck紧的变分

In this article, we study the variation of the Gieseker and Uhlenbeck compactifications of the moduli spaces of Mumford-Takemoto stable vector bundles of rank 2 by changing polarizations. Some {\it canonical} rational morphisms among the Gieseker compactifications are proved to exist and their fibers are studied. As a consequence of studying the morphisms from the Gieseker compactifications to the Uhlebeck compactifications, we show that there is an everywhere-defined {\it canonical} algebraic map between two adjacent Uhlenbeck compactifications which restricts to the identity on some Zariski open subset.

外文数据库

带个人航位推算系统的非 GPS 导航

This paper introduces a positioning system for walking persons, called """"Personal Dead-reckoning"""" (PDR) system. The PDR system does not require GPS, beacons, or landmarks. The system is therefore useful in GPS-denied environments, such as inside buildings,""

外文数据库

等离子体加速器中的韦克菲尔德再生

Plasma wakefields offer high acceleration gradients, orders of magnitude larger than conventional RF accelerators. However, the achievable luminosity remains relatively low, typically limited by the plasma recovery time and the charge which can be accelerated per shot. In this work, we show that a train of drive bunches can be harnessed to accelerate multiple witness bunches in a single shot. We demonstrate that periodically loading the wakefields removes the limit on the energy transfer from the drive beam to the plasma, which allows the luminosity to be increased. Proof-of-concept simulations for the AWAKE scheme are carried out to demonstrate the technique, achieving a doubling of the accelerated charge while exploiting only a fraction of the drive train.

外文数据库

高温与低温斑马（Na/NiCl2）电池性能

TheeffectofoperatingtemperatureonperformanceandagingofZebracellswasinvestigated.Thecellswerecycledat260 °Cand350 °Cusingamodifiedchargingregimetoacceleratedamage.Thecathodeandsolidelectrolyteofdegradedcellsattheendofcyclingwereanalyzedbyscanningelectronmicroscopy,energydispersivespectroscopyandX-raydiffraction.ItishypothesizedthattheformationofAlF3onthesurfaceoftheβ?aluminaelectrolytecontributestothefailureofcellsatlowtemperatures.Amechanismbasedontheoverchargereactionisproposedfortheformationofthisphase.At350 °C,asignificantcapacitylosswasobservedwithcyclelife,whichcorrelatestonickelparticlegrowthasthecauseofthisphenomenon.ThefactorsresponsibleforNigraingrowtharediscussed.

外文数据库

锂离子阴极LiMn1.5Ni0.5O4液固界面厚度和组成的原位测定

Usingneutronreflectometry,wehavedeterminedthethicknessandscatteringlengthdensityprofileoftheelectrode鈥揺lectrolyteinterfaceforthehigh-voltagecathodeLiMn1.5Ni0.5O4insituatopencircuitvoltageandfullydelithiated.Uponexposuretoaliquidelectrolyte,athin3.3nmLi-richinterfaceformsduetotheorderingoftheelectrolyteonthecathodesurface.Thisinterfacechangesincomposition,asevidentbyanincreaseinthescatteringlengthdensityofthenewlayer,withchargingasthecondensedlayerevolvesfrombeinglithiumrichtoonecontainingamuchhigherconcentrationofFfromtheLiPF6salt.Theseresultsshowthesurfacechemistryevolvesasafunctionofthepotential.Keywords:liquid鈭抯olidinterface;Liionbatteries;SEIlayer;insitubattery;neutronreflectometry

外文数据库

太阳不透明度、中微子信号和日震学

In connection with the recent suggestion by Tsytovich et al. that opacity in the solar core could be overestimated, we consider the following questions: i) What would a 10\% opacity reduction imply for the solar neutrino puzzle? ii) Is there any hope of solving the solar neutrino puzzle by changing opacity? iii) Is a 10\% opacity reduction testable with helioseismological data?

外文数据库

（-2）-球体的爆破公式

Let $X$ be a simply connected 4-manifold containing a $(-1)$-sphere $e$. Fintushel and Stern prove that $$ D_c(\exp(te)) = D_c(B(t)) on e^\perp if c\cdot e is even, $$ $$ D_c(\exp(te)) = D_{c-e}(S(t)) on e^\perp if c \cdot e is odd, $$ for some universal series $B(t),S(t) \in \Q[x][[t]]$ with $x$ the class of a point. We show that their method can easily be extended to $(-2)$-spheres $\tau$ to give blow up formulas like $$ D_c(\exp(t\tau)) = D_c(B^2(t) + S^2(t)/2 \tau^2) on \tau^perp if c\cdot \tau is even. $$

外文数据库

绘制低温原子探针的路径生物分子层析成像分析

The understanding of protein structure, folding, and interaction with other proteins remains one of the grand challenges of modern biology. Tremendous progress has been made thanks to X-ray- or electron-based techniques that have provided atomic configurations of proteins, and their solvation shell. These techniques though require a large number of similar molecules to provide an average view, and lack detailed compositional information that might play a major role in the biochemical activity of these macromolecules. Based on its intrinsic performance and recent impact in materials science, atom probe tomography (APT) has been touted as a potential novel tool to analyse biological materials, including proteins. However, analysis of biomolecules in their native, hydrated state by APT have not yet been routinely achieved, and the technique's true capabilities remain to be demonstrated. Here, we present and discuss systematic analyses of individual amino-acids in frozen aqueous solutions on two different nanoporous metal supports across a wide range of analysis conditions. Using a ratio of the molecular ions of water as a descriptor for the conditions of electrostatic field, we study the fragmentation and behavior of those amino acids. We discuss the importance sample support, specimen preparation route, acquisition conditions and data analysis, to pave the way towards establishing guidelines for cryo-APT analysis of biomolecules.

外文数据库

为自动检测Drosophicola suzukii进行深入学习:无人驾驶飞行器监测的潜力

外文数据库

对未知敌对领土上空的多架无人机进行参数控制

A methodology for real-time control of unmanned air vehicles (UAV) in the absence of a-priori knowledge of hostile territory is presented. The control methodology generates a sequence of waypoints to be pursued by the UV until the goal is reached. The controller computes the waypoints every time new information is obtained regarding the presence or absence of a hostile agent at a particular grid of the territory. The waypoints are the result of an A* search. The cost function of the search is a weighted combination of dangers arising due to probability of being hit by the attacks of hostile terrestrial agents on the ground and the danger of UAV grounded as a result of its prolonged stay over the hostile territory. The multi-agency in the system is due to the broadcast of newly observed information by an UAV to its remaining counterparts. The sequence of waypoints defines the path of the UAV to its goal. By varying the corresponding weights the paths can be altered to obtain a particular performance criterion. Simulation results are presented for various parametric combinations to validate the methodology.

外文数据库

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