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There exists a family $\{B_{\alpha}\}_{\alpha<\omega_1}$ of sets of countable ordinals such that o $\max B_{\alpha}=\alpha$, o if $\alpha\in B_{\beta}$ then $B_{\alpha}\subseteq B_{\beta}$, o if $\lambda\leq \alpha$ and $\lambda$ is a limit ordinal then $B_{\alpha}\cap\lambda$ is not in the ideal generated by the $B_{\beta}$, $\beta<\alpha$, and by the bounded subsets of $\lambda$, o there is a partition $\{A_n\}_{n=0}^{\infty}$ of $\omega_1$ such that for every $\alpha$ and every $n,$ $B_{\alpha}\cap A_n$ is finite.

外文数据库

用于双功能金属的高活性非贵金属钙钛矿电催化剂鈥揂ir电池电极

Perovskitesareofgreatinterestasreplacementsforpreciousmetalsandoxidesusedinbifunctionalairelectrodesinvolvingtheoxygenevolutionreaction(OER)andoxygenreductionreaction(ORR).Herein,wereportthesynthesisandactivityofaphase-purenanocrystalperovskitecatalystthatishighlyactivefortheOERandORR.TheOERmassactivityofLaNiO3,synthesizedbythecalcinationofarapidlydriednanoparticledispersionandsupportedonnitrogen-dopedcarbon,isdemonstratedtobenearly3-foldthatof6nmIrO2andexhibitsnohysteresisduringoxygenevolution.Moreover,strongOER/ORRbifunctionalityisshownbythelowtotaloverpotential(1.02V)betweenthereactions,onparorbetterthanthatofnoblemetalcatalystssuchasPt(1.16V)andIr(0.92V).Theseresultsareexaminedinthecontextofsurfacehydroxylation,andanewOERcycleisproposedthatunifiestheoryandtheuniquesurfacepropertiesofLaNiO3.Keywords:perovskite;catalyst;bifunctional;metal鈭抋irbattery;oxygenevolution;oxygenreduction;wateroxidation

外文数据库

这个4_4 ：$量子场论，II。Wick核的可积性

We continue the construction of the $:\phi^4_4:$ quantum field theory. In this paper we consider the Wick kernel of the interacting quantum field. Using the complex structure and the Fock-Bargmann-Berezin-Segal integral representation we prove that this kernel defines a unique operator--valued generalized function on the space $\Sc^\alpha(\R^4)$ for any $\alpha<6/5,$ i.e. the constructed quantum field is the generalized operator-valued function of localizable Jaffe class. The same assertion is valid for the outgoing quantum field. These assertions about the quantum field allow to construct the Wightman functions, the matrix elements of the quantum scattering operator and to consider their properties (positivity, spectrality, Poincare invariance, locality, asymptotic completeness, and unitarity of the quantum scattering).

外文数据库

金属装饰石墨烯及其氮化硼类似物作为多功能储能材料：为无线传感器节点的锂离子电池提供参考

•TheB-dopedgraphyneisapromisingcandidateforLithium-ionbatteryanodematerial.•Themetaladsorbedonthehollowsiteof12-atomhexagonalringismorepreferable.•EachM(Ni,Cr,Pd)atomcanadsorbuptothreeH2molecules.•GraphyneandBN-ynearepromisingsubstratesforhydrogenstorageatroomtemperature.

外文数据库

对称性、可积链模型与随机过程

A general way to construct chain models with certain Lie algebraic or quantum Lie algebraic symmetries is presented. These symmetric models give rise to series of integrable systems. As an example the chain models with $A_n$ symmetry and the related Temperley-Lieb algebraic structures and representations are discussed. It is shown that corresponding to these $A_n$ symmetric integrable chain models there are exactly solvable stationary discrete-time (resp. continuous-time) Markov chains whose spectra of the transition matrices (resp. intensity matrices) are the same as the ones of the corresponding integrable models.

外文数据库

潮汐触发椎间盘增厚。二、结果和解释

We have reported in a previous paper (AAS 116, 417, 1996) B, V and I band photometric data for a sample of 24 edge-on interacting spiral galaxies, together with a control sample of 7 edge-on isolated galaxies. We discuss here the main result found in this study: the ratio h/z of the radial exponential scalelength h to the constant scaleheight z is about twice smaller for interacting galaxies. This is found to be due both to a thickening of the plane, and to a radial stripping or shrinking of the stellar disk. If we believe that any galaxy experienced a tidal interaction in the past, we must conclude that continuous gas accretion and subsequent star formation can bring back the ratio h/z to higher values, in a time scale of 1 Gyr.

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智慧城市中的无人机路由：一种实时解决团队定向问题的偏随机算法

The concepts of unmanned aerial vehicles and self-driving vehicles are gaining relevance inside the smart city environment. This type of vehicles might use ultra-reliable telecommunication systems, Internet-based technologies, and navigation satellite services to decide about the routes they must follow to efficiently accomplish their mission and reach their destinations in due time. When working in teams of vehicles, there is a need to coordinate their routing operations. When some unexpected events occur in the city (e.g., after a traffic accident, a natural disaster, or a terrorist attack), coordination among vehicles might need to be done in real-time. Using the team orienteering problem as an illustrative case scenario, this paper analyzes how the combined use of extremely fast biased-randomized heuristics and parallel computing allows for ‘agile’ optimization of routing plans for drones and other autonomous vehicles."

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JAXA联合循环发动机的研究现状

外文数据库

系泊矿井负载分离运动

Motion equations of moored mine load separation is derived. Based on proper engineering assumptions for mooring line, system viewpoint is used to found the motion equations, and the D'Alembert principle is used to eliminate the constraint force of mooring

外文数据库

利用无人机从大规模无线传感器网络收集数据

Nowadays, with the developing technology, the use of Unmanned Aerial Vehicles (UAVs) has become quite common. With the increase in the use of UAVs in the military and civilian area, the studies in UAVs are also increasing. Minimizing the costs and improving safety play an important role in the development of these systems according to different terms of use. UAV route planning is quite a difficult problem when multiple tasks exist that contain the multiple target point and also considering the constraints of the environment. The aim of this study is to achieve appropriate route planning with UAVs in a Wireless Sensor network environment, to collect data on the nodes. In MATLAB, implementation is reviewed with genetic algorithm method in a three-dimensional radar threatened environment. And obtained results shows that the proposed model is fast and produce an acceptable solution.

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快速锂离子导体 Li1+yTi2-yAly(PO4)3 改性 Li1.2[Mn0.54Ni0.13Co0.13]O2 作为高性能锂离子电池正极材料

InthematerialofxLi2MnO3·(1-x)LiMO2(0?

外文数据库

一种基于弹力绳算法的无人机路径规划方法

In this paper, we design a path planning algorithm for UAV with maneuverability constraints. In the task of UAV path planning, it is necessary to ensure that UAV does not collide with obstacles and maintain a certain safe distance. At the same time, the obtained path should meet the maneuverability requirements of UAV. According to the definition of elastic rope in [1], we analyze the limitations of the elastic rope algorithm and give the design scheme of the algorithm for UAV path planning. Finally, we design several simulation scenarios to verify the performance of the algorithm. From the simulation results, we can see that the designed algorithm has a good performance in UAV path planning.

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4-乙烯基吡啶同时聚合和季铵化制备用于非水钒氧化还原液流电池的阴离子交换膜

Asimple,singlestepandenvironmentallyfriendlyprocessisdevelopedforthesynthesisofanionexchangemembrane(AEM)bysimultaneouspolymerizationandquaternization,unliketheconventionalmembranesynthesiswhichconsistsofseparatepolymerizationandquaternizationstep.Themembranesynthesisiscarriedoutbydissolvingpolyvinylchloride(PVC)incyclohexanonealongwith4-vinylpyridine(4VP)and1,4-dibromobutane(DBB)inthepresenceofthermalinitiatorbenzoylperoxide,followedbyfilmcastingtogetthinandflexibleAEMs.Themembranepropertiessuchasionexchangecapacity,ionicconductivityandswellingbehaviouraretunedbyvaryingthedegreeofcrosslinking.TheseAEMsexhibitlowvanadiumpermeability,whileretaininggooddimensionalandchemicalstabilityinanelectrolytesolution,makingthemappropriatecandidatesfornon-aqueousvanadiumacetylacetonateredoxflowbattery(VRFB)applications.Theoptimizedmembranedisplaysionexchangecapacityandionicconductivityof2.0?mequiv?g?and0.105?mS?cm?,respectively,whereastheefficiencyof91.7%,95.7%and87.7%forcoulombic,voltageandenergyparameterinnon-aqueousVRFB,respectively.Thisstudyrevealsthatthenon-aqueousVRFBperformanceisgreatlyinfluencedbymembraneproperties;thereforetheoptimalcontroloverthemembranepropertiesisadvantageousfortheimprovedperformance.

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自主机器人任务的自学习范式人工行为系统的行为生成策略

In this study, behavior generation and self-learning paradigms are investigated for the real-time applications of multi-goal mobile robot tasks. The method is capable to generate new behaviors and it combines them in order to achieve multi goal tasks. The proposed method is composed from three layers: Behavior Generating Module, Coordination Level and Emotion -Motivation Level. Last two levels use Hidden Markov models to manage dynamical structure of behaviors. The kinematics and dynamic model of the mobile robot with non-holonomic constraints are considered in the behavior based control architecture. The proposed method is tested on a four-wheel driven and four-wheel steered mobile robot with constraints in simulation environment and results are obtained successfully.""

外文数据库

无人机无线功率传输：轨迹设计和能量优化

This paper studies a new unmanned aerial vehicle (UAV)-enabled wireless power transfer system, where a UAV-mounted mobile energy transmitter is dispatched to deliver wireless energy to a set of energy receivers (ERs) at known locations on the ground. We investigate how the UAV should optimally exploit its mobility via trajectory design to maximize the amount of energy transferred to all ERs during a finite charging period. First, we consider the maximization of the sum energy received by all ERs by optimizing the UAV's trajectory subject to its maximum speed constraint. Although this problem is non-convex, we obtain its optimal solution, which shows that the UAV should hover at one single fixed location during the whole charging period. However, the sum-energy maximization incurs a “near-far” fairness issue, where the received energy by the ERs varies significantly with their distances to the UAV's optimal hovering location. To overcome this issue, we consider a different problem to maximize the minimum received energy among all ERs, which, however, is more challenging to solve than the sum-energy maximization. To tackle this problem, we first consider an ideal case by ignoring the UAV's maximum speed constraint, and show that the relaxed problem can be optimally solved via the Lagrange dual method. The obtained trajectory solution implies that the UAV should hover over a set of fixed locations with optimal hovering time allocations among them. Then, for the general case with the UAV's maximum speed constraint considered, we propose a new successive hover-and-fly trajectory motivated by the optimal trajectory in the ideal case and obtain efficient trajectory designs by applying the successive convex programing optimization technique. Finally, numerical results are provided to evaluate the performance of the proposed designs under different setups, as compared with benchmark schemes.

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Ia型超新星在星云相中的红外光谱和光学光谱

We present near-infrared (NIR) spectra for Type Ia supernovae at epochs of 13 to 338 days after maximum blue light. Some contemporary optical spectra are also shown. All the NIR spectra exhibit considerable structure throughout the J-, H- and K-bands. In particular they exhibit a flux `deficit' in the J-band which persists as late as 175 days. This is responsible for the well-known red J-H colour. To identify the emission features and test the $^{56}$Ni hypothesis for the explosion and subsequent light curve, we compare the NIR and optical nebular-phase data with a simple non-LTE nebular spectral model. We find that many of the spectral features are due to iron-group elements and that the J-band deficit is due to a lack of emission lines from species which dominate the rest of the IR/optical spectrum. Nevertheless, some emission is unaccounted for, possibly due to inaccuracies in the cobalt atomic data. For some supernovae, blueshifts of 1000--3000 km/s are seen in infrared and optical features at 3 months. We suggest this is due to clumping in the ejecta. The evolution of the cobalt/iron mass ratio indicates that $^{56}$Co-decay dominates the abundances of these elements. The absolute masses of iron-group elements which we derive support the basic thermonuclear explosion scenario for Type Ia supernovae. A core-collapse origin is less consistent with our data.

外文数据库

用于长寿命太阳能无线传感器网络节点的综合优化混合储能系统

Solarenergyharvestingispromisingtoprovidelong-termpowerautonomyforwirelesssensornetworks.Energystoragedeviceslikelithium-ionbatteriesareusuallyintegratedtosolar-poweredsensornodestoovercometheintermittencyofsolarpower.However,thecyclelifeoflithium-ionbatteriesisshort,whichlimitsthelifetimeofthenodes.Therefore,supercapacitor-batteryhybridenergystoragesystemhasbeenusedtoextendthecyclelifeofbattery.Thedesignofhybridenergystoragesystemssignificantlyaffectstheperformanceofwirelesssensornetworknodesinmanyways.However,hybridenergystoragesystemoptimizationisacomprehensiveproblembecausetheconfigurationandpower-splitstrategyneedtobeconsideredconcurrently,whichhasnotbeendoneintheexistingstudiesofsolar-poweredsensornodes.Inthisstudy,atwo-porthybriddiodetopologyisproposed,accompaniedbyanadaptivesupercapacitorbufferenergymanagementstrategytoachieveintegratedoptimization.Thehybriddiodesemi-activetopologyusesaunidirectionalDC/DCconverteraccompaniedbytwodiodestoreplacethebidirectionalDC/DCconverterintheexistingsemi-activetopology.Accordingly,theenergyloseisdecreasedby15.5%whilethecost,size,andcontrollingcomplexityarealsodecreased.Moreover,anadaptivesupercapacitorbufferenergymanagementstrategyisdesignedbasedonthenewtopologytodecreasethebatterydegradation.Simulationandexperimentalresultsindicatethattheproposedhybridenergystoragesystemincreasesthebatterylifetimetoatleast3timesthatofexistinghybridenergystoragesystems.Finally,along-lifesolar-poweredwirelesssensornetworknodewitharelativelysmallsizeandcostisachievable.

外文数据库

用于混合动力电动汽车 (HEV) 的高压动力电池保护装置架构

外文数据库

为无人机提供动力的带有卷绕器的绳索的动态特性

To ensure continuous, twenty four hour operation of a multi-rotor unmanned aerial vehicle (UAV), a powering rope, providing electrical power supply to the vehicle, is applied. The UAV flies over the board of a sea vessel and is equipped with a camera (vision) system. The vision system looks round the vessel to detect possible dangerous obstacles, that cannot be detected using standard collision avoidance systems, like AIS (automatic identification system) or marine radars. The powering rope is wound in the winder, mounted at the vessel’s board. The winder maintains a prescribed tension in the rope to prevent it from loose hanging and consequently from chaotic movements in the wind. Model of rope’s dynamics is formulated using the rigid finite element approach. Damping properties of the rope, as well as its aerodynamic lift and drag forces are included. Rope length reduction when winding is modelled. Finally dynamic characteristics of the rope are obtained and their importance for proper UAV flight control is demonstrated.

外文数据库

CMB映射中的弱Lensing检测

The weak lensing effects are known to change only weakly the shape of the power spectrum of the Cosmic Microwave Background (CMB) temperature fluctuations. I show here that they nonetheless induce specific non-Gaussian effects that can be detectable with the four-point correlation function of the CMB anisotropies. The magnitude and geometrical dependences of this correlation function are investigated in detail. It is thus found to scale as the square of the derivative of the two-point correlation function and as the angular correlation function of the gravitational displacement field. It also contains specific dependences on the shape of the quadrangle formed by the four directions. When averaged at a given scale, the four-point function, that identifies with the connected part of the fourth moment of the probability distribution function of the local filtered temperature, scales as the square of logarithmic slope of its second moment, and as the variance of the gravitational magnification at the same angular scale. All these effects have been computed for specific cosmological models. It is worth noting that, as the amplitude of the gravitational lens effects has a specific dependence on the cosmological parameters, the detection of the four-point correlation function could provide precious complementary constraints to those brought by the temperature power spectrum.

外文数据库

电池缓冲智能负载控制器的能量损失评估

Thispaperaimstoevaluatetheenergyandpowerlossofasingle-phasebattery-bufferedsmartload(BBSL)underdemand-sideprimaryfrequencycontrol(PFC).TheBBSLconsistsofabatteryandapower&energymanagementsystem(PEMS),theevaluationinthisworkentailstheexperimentalmeasurementoftheenergylostinthebatteryduringthechargeanddischargeproceduresdictatedbythePFCandthemeasurementofthepowerlostinthePEMS.Amethodisdevelopedtomeasurethebatteryenergylossusingthesmartloadstrategybymaintainingthebatterystateofcharge(SOC)constantoverthePFCregulationperiod.TheeffectsofthePFCdroopcharacteristicsanddead-bandsonbatteryenergylossarestudied.Theexperimentalmeasurementsoftheenergylossareconfirmedbysimulationofabatterymodelinwhichthetotalvoltagedropofthebatteryisrepresentedbyanonlinearcurrent-dependentresistance.Then,thepowerlossassociatedwiththepowerelectronicconvertersofthePEMSisexperimentallydeterminedunderdifferentPFCdroopanddead-bandsettings.

外文数据库

通过结晶动力学的微观结构控制优化Li2S-P2S5玻璃陶瓷的锂离子电导率

ToimprovetheLiionconductivityinaglass-ceramicsolidelectrolyte,themicrostructuralcontrolforLi2S-P2S5glassceramicswasinvestigatedbasedoncrystallizationkinetics.75Li2S?25P2S5(mol.%)glasswassynthesizedbyaball-millingmethod,andglass-ceramicswerepreparedbycrystallizationwithheattreatmentatvarioustemperatureswithappropriateholdingtimes.Crystallizationkinetics—nucleationrate,I,andcrystalgrowthrate,U,of75Li2S?25P2S5glass—weredeterminedbydifferentialthermalanalysisandinsitutransmissionelectronmicroscopy(TEM).Theobtainedparameterswerereferredtooptimizetheheattreatmentconditions.Throughtheoptimization,Liionconductivitywasimprovedby80%incomparisonwiththeglasselectrolyte,inwhichaconductivityof1.33?×?10?3?S?cm?1wasachievedatroomtemperaturebycontrollingthemicrostructureandtheformationofanetworkstructureintheglassmatrix.Thisapproachbringsoutthebestperformanceof75Li2S?25P2S5glass-ceramics.Theeffectivemediumtheorywasadoptedtodiscusstheformationofafastion-conductingnetworkfortheimprovementofLiionconductivity.Thepresentmethodcanprovideaneffectivepreparationrouteofaglass-ceramicsolidelectrolyteforall-solidLi-ionbatteries.

外文数据库

使用 USBL 成功 AUV Docking 和成功 AUV 的导航概率评估?

This paper addresses the navigation of an autonomous underwater vehicle (AUV) when approaching a docking station. The following array of underwater navigation sensors is considered available: ultra short baseline (USBL), Doppler velocity log (DVL) with bottom track, compass, and gyro. Based on this sensor array, we propose a modular and cascaded Kalman filter (KF) approach to estimate the vehicle's heading, azimuth and angle to the docking station, position, and velocity.

We also propose to use the information from the KF covariance to compute, in real time, the probability of a successful docking. This method uses the navigation covariance and the characteristics of the docking station to predict the outcome of the docking procedure. The method enables the AUV to determine if a docking maneuver is feasible, hence improving the overall AUV autonomy level and allowing the AUV to assess whether corrective measures are required.

外文数据库

锂离子电池：可呼吸的无碳电极：用于稳定Li-O2电池的具有分级有序多孔结构的黑色TiO2（Adv.EnergyMater.19/2017）

Itisconfirmedthatoxygen-deficientblackTiO2canoperateasastablecathodeforLi-O2batteries,wherethemorphologyofblackTiO2wasmodifiedtobehierarchicallyporous.Thisinnovativecathoderendersthereactionmoleculesandair(O2)topermeatereversibly,analogoustothefunctionofthehumanrespiratorysystem,whilegeneratingelectricityfromthereactionsofLiandoxygen.ThisisreportedbySeunghoonNam,YongjoonPark,ByungwooPark,andco-workersinarticlenumber1700814.

外文数据库

重新审视用于电动汽车的聚阴离子 LiFePO4 电池材料

AlthoughoxidecathodeshavebeenwidelyusedintheseLi-ionbatteries,thesecathodessufferfrominstabilityoftheoxygenclose-packedstructure.Incontrast,polyanionicphosphatessuchasLiFePO4haveincrediblelatticestabilityandsafetyfeaturesowingtothestrongcovalentbondofP–O,whichconstrainstheoxygenatomsandminimizesthedefectsoftheoxygensite,resultinginstableframeworks.Inaddition,thepresenceofthestrongP–Ocovalentbondstabilizestheanti-bondingtransitionalmetalredoxcouplethroughanM–O–Pinductiveeffecttogeneratearelativelyhighpotential.Hence,polyanionicLiFePO4hasbeenanidealchoiceofcathodematerialsforbatteriesdeployedinelectricvehicles.Inthisreview,werevisitthebasicfeaturesanddevelopmentofLiFePO4,asanattempttospeedingitsfuturedeploymentinmassiveelectricvehicles.

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基于改进智能水滴算法的无人机气象感知路径规划

A wide range of applications of the unmanned aerial vehicle (UAV) have been observed in the past few years, and path planning is one of the most critical issues that require to be resolved. UAVs are still prone to meteorological impediments such as thunderstorms, ice accumulation, and severe convective weather for the safety of flights. This paper proposes a meteorology-aware path planning method based on the improved intelligent water drops (IIWD) algorithm. The algorithm consists of both static and dynamic path planning. In the static path planning phase, ice accumulation and the Richardson number are considered when determining the trajectory with low risk. In the dynamic path planning phase, the latest forecast products are adopted to modify the planned path, and the virtual potential force is applied to adjust the flight direction of the UAV when encountered with severe convective weather. The validation and efficiency of the proposed algorithm are verified via simulations in comparison with the ant colony optimization, genetic algorithm, and Q-learning algorithm, where the quality of our algorithm's performance in terms of flight time and risk degree is determined. Meanwhile, the risk degree of the UAV flight path at different altitudes is analyzed. The simulation results show that the average flight speed decreases, and the risk degree increases along with the descending of the flight altitude, respectively, which is found to be in consensus with the theory of meteorology.

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基于量子启发算法的高效分子构象生成

Conformation generation, also known as molecular unfolding (MU), is a crucial step in structure-based drug design, remaining a challenging combinatorial optimization problem. Quantum annealing (QA) has shown great potential for solving certain combinatorial optimization problems over traditional classical methods such as simulated annealing (SA). However, a recent study showed that a 2000-qubit QA hardware was still unable to outperform SA for the MU problem. Here, we propose the use of quantum-inspired algorithm to solve the MU problem, in order to go beyond traditional SA. We introduce a highly-compact phase encoding method which can exponentially reduce the representation space, compared with the previous one-hot encoding method. For benchmarking, we tested this new approach on the public QM9 dataset generated by density functional theory (DFT). The root-mean-square deviation between the conformation determined by our approach and DFT is negligible (less than about 0.5 Angstrom), which underpins the validity of our approach. Furthermore, the median time-to-target metric can be reduced by a factor of five compared to SA. Additionally, we demonstrate a simulation experiment by MindQuantum using quantum approximate optimization algorithm (QAOA) to reach optimal results. These results indicate that quantum-inspired algorithms can be applied to solve practical problems even before quantum hardware become mature.

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使用 Logistic 曲线生成穿越窗口的可飞行轨迹*

This work considers point-to-point flyable trajectory generation through constrained planar regions referred as windows. A four parameter logistic curve trajectory planning tool is proposed for generating feasible trajectories that (i) connect the given initial and final positions with (ii) smooth bounded velocity and acceleration variations (flyability), and (iii) pass through the prescribed windows. A two-step approach is proposed, first narrowing down the search space to a restricted set in six dimensions, parameterizing a variety of trajectories that satisfy the derived closed-form flyability conditions. The final solutions are found by sampling that set using closed-form window traversal conditions. Numerical examples are presented to analyze the performance of the proposed approach in terms of number of solutions and computation time.

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植入式电子：面向无电池的全打印、无线、可拉伸植入式生物系统，实时监测脑动脉瘤血流动力学（Adv.Sci.1919）

Inarticlenumber1901034,Woon‐HongYeoandco‐workersintroduceafullyprinted,wireless,stretchableimplantablebiosystem.Acomprehensivestudyofnanoinkpreparationandparameteroptimizationenablesalow‐profile,multi‐layerprintingofthehigh‐performance,capacitanceflowsensor.Atransient,wirelessinductivecouplingmethodallowsforwirelessdetectionofbiomimeticcerebralaneurysmhemodynamicswiththemaximumreadoutdistanceof6cmthroughmeat.

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硼簇合物作为高稳定性镁电池电解液

Boronclustersareproposedasanewconceptforthedesignofmagnesium-batteryelectrolytesthataremagnesium-battery-compatible,highlystable,andnoncorrosive.Anovelcarborane-basedelectrolyteincorporatinganunprecedentedmagnesium-centeredcomplexanionisreportedandshowntoperformwellasamagnesium-batteryelectrolyte.Thisfindingopensanewapproachtowardsthedesignofelectrolyteswhoselikelihoodofmeetingthechallengingdesigntargetsformagnesium-batteryelectrolytesisveryhigh.

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具有高理论能量密度的电池

Exploringalternativerechargeablebatterieswithenergydensitiesabovestate-of-the-artlithium-ionbatteriesisthecriticalchallengeforbothacademiaandindustry.Herein,thermodynamiccalculationsareperformedtoobtain:1)theoreticalenergydensities(basedonthecathodeandanodeactivematerials)of1683kindsofbatteriesofconversionreactionchemistryusingLi,Na,K,Mg,Al,andZnastheanodes;and2)electromotiveforce(EMF,alsoknownasthermodynamicequilibriumvoltage)ofthesebatteries.Amongthesebatteries,theoreticalenergydensityabove1000??Whkg?1,800??WhL?1andEMFover1.50??Varetakenasthescreeningcriteriatorevealsignificantbatterysystems.Inaddition,hazardandcostissuesareexamined.Ultimately,thereare51kindsofbatteriessatisfyingthescreeningcriteria,includingO2/Li,O2/Al,O2/Mg,H2O/Li,CO2/Li,S/Li,CO2/Al,H2O/Albatteries.Moreover,practicalenergydensitiesofthecellsareestimatedusingasolid-statepouchcellwithelectrolyteofPEO/LiTFSI.Knowingthebatterieswithhighenergydensitieswillguidetheresearchanddevelopmentonthenext-generationenergystorage."

外文数据库

战斗力救援工具的先驱。。。自1994年以来！

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高性能锂硫电池用全氟磺酸离子筛改性隔膜的合理设计

PracticalapplicationofLi-Sbatteryislimitedbythefastcapacitydecayandlowcoulombicefficiencycausedbytheshuttlingphenomenon.Modificationofthebatteryseparatortoimparttheseparatorwithionicsievingpropertyisaneffectivestrategytoalleviatetheshuttlingphenomenon.Inthisstudy,perfluorinatedsulfonicacid(PFSA)ionomerswithdifferentequivalentweight(EW)valuesareusedtomodifythecommercialpolyethyleneseparator,andtheelectrochemicalperformanceoftheseseparatorsissystematicallyinvestigated.OurresultsshowthattheseparatormodifiedusingPFSAionomerwithalowEWvalueof830showsoptimalbatteryperformanceowingtoitsuniquestructureoftheioniccluster.TheLi-Sbatterywiththismodifiedseparatorshowsaninitialdischargecapacityof1352?mAhg?1andaretainedcapacityof931.6?mAhg?1aftercycling100timesat0.2C,whichdemonstratestheeffectivenessofthismodificationstrategy.Furthermore,thecorrelationbetweenthepropertiesofPFSAionomersandtheelectrochemicalperformanceofthemodifiedseparatorunveiledinthisstudymayprovideinsightfortherationaldesignofadvancedseparatorforbatteryapplications.

外文数据库

双功能磷酸铁锂改性隔膜用于低过电位和稳定的锂硫电池

Lithiumsulfide(Li2S)compoundsascathodematerialsforLithium-sulfur(Li-S)batteryhaveattractedmoreandmoreattentionrecentlybecauseofitshighspecificcapacity,lowervolumeexpansionandhigherthermalstabilityofLi2S.However,highelectrochemicalbarrieroftheLi2Scathodeand“shuttleeffect”fromSspeciesonanodestillblockthedevelopmentofLi-Sbatteries.Herein,LiFePO4(LFP)isemployedasdual-functionseparatormodifiertoestablishhybridcathode.Themodifiedseparatorwillreduceoverpotentialforeffectiveanddurablesulfurredoxreactionsatthesametime,itcanalsoefficientlyimmobilizethelithiumpolysulfides(LiPSs)throughtheLewisacid-baseinteractionofLiPSsandLFP.Thebatterysystemsbasedontheas-developedLFPmodifiedseparatorexhibitanexcellentratecapability,highsulfurutilizationandoutstandingcyclingperformance.Thecapacityretentioncanreach83.9%after400cyclesat0.2?C,andthecapacitycanreach594?mAh?g?1atupto2?C.Currentfacileandlow-coststrategytomodifiedLi-Sbatterysystemsononehandoffersaneffectivepathwaytoenhanceelectrochemicalperformance,ontheotherhandinspirenewstrategiesonreducingtheactivationbarrierofLi2Sforimprovedsulfurelectrochemistryaswell.

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用于无人机的重燃料发动机

The growing usage of Unmanned Aerial Vehicles (UAV's) for aerial surveillance and reconnaissance in military applications calls for lightweight, reliable powerplants that burn heavy distillate fuels. While mass-produced engines exist that provide adequate power-to-weight ratio in the low power class needed for UAV's, they all use a spark-ignited combustion system that requires high octane fuels. Southwest Research Institute (SwRI) has embarked upon an internal research effort to design and demonstrate an engine that will meet the requirements of high power density, power output compatible with small unmanned aircraft, heavy-fuel combustion, reliable, durable construction, and producible design. This effort has culminated in the successful construction and operation of a demonstrator engine. The engine characteristics are suitable for other applications that require compact heavy fuel powerplants, including hybrid vehicles and portable power equipment. The demonstrator engine is rated at 22.4 kW (30hp), and weighs 18.8 kg (41.5 lbs). Weight reductions for production will result in a final weight of about 15.9 kg (35 lbs). It uses a prechamber combustion system, with conventional off-the-shelf fuel injection components. It is a two-cycle air-cooled engine, with a displacement of 523 cc (16.4 in3) in two horizontally- opposed power cylinders. Unique features include separate pistons and cylinders driving the scavenging air, unit castings of the power and compressor cylinders, and reed valves controlling the transfer ports. Discussed in this paper are the design approach, the trade studies, and the design analysis performed in designing a prototype engine, as well as the advanced methods of prototyping, and the results of prototype demonstration testing

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SDN 无人机辅助车辆计算卸载的新型成本优化策略

Vehicular computation offloading is a well-received strategy to execute delay-sensitive and/or compute-intensive tasks of legacy vehicles. The response time of vehicular computation offloading can be shortened by using mobile edge computing that offers strong computing power, driving these computation tasks closer to end users. However, the quality of communication is hard to guarantee due to the obstruction of dense buildings or lack of infrastructure in some zones. Unmanned Aerial Vehicles (UAVs), therefore, have become one of the means to establish communication links for the two ends owing to its characteristics of ignoring terrain and flexible deployment. To make a sensible decision of computation offloading, nevertheless vehicles need to gather offloading-related global information, in which Software-Defined Networking (SDN) has shown its advances in data collection and centralized management. In this paper, thus, we propose an SDN-enabled UAV-assisted vehicular computation offloading optimization framework to minimize the system cost of vehicle computing tasks. In our framework, the UAV and the Mobile Edge Computing (MEC) server can work on behalf of the vehicle users to execute the delay-sensitive and compute-intensive tasks. The UAV, in a meanwhile, can also be deployed as a relay node to assist in forwarding computation tasks to the MEC server. We formulate the offloading decision-making problem as a multi-players computation offloading sequential game, and design the UAV-assisted Vehicular computation Cost Optimization (UVCO) algorithm to solve this problem. Simulation results demonstrate that our proposed algorithm can make the offloading decision to minimize the Average System Cost (ASC).

外文数据库

基于偏置校正技术的电动汽车多电池组系统充电状态估计框架

•Biascorrectionforsinglecellsbasedonanaveragepackmodelisproposed.•Anintegratedmethodforbatterymodelingandparameteridentificationisproposed.•ARBFneuralnetworkbaseduncertaintyquantificationalgorithmisproposed.•AsystematicSoCestimationframeworkformulti-cellbatterypackisproposed.

外文数据库

FMCW CSAR 信号特性分析与脉冲内运动补偿

The combination of frequency modulation continuous wave (FMCW) technology and circular synthetic aperture radar (CSAR) would pave the way for the development of the microminiature unmanned aerial vehicle (UAV) earth observation application. Regarding the FMCW CSAR imaging process, the stop-and-go approximation is no longer effective due to the longer pulse duration. In addition, the signal characteristics of FMCW CSAR with higher frequency band and higher resolution need to be further studied. Aiming at millimeter-wave FMCW CSAR imaging, the signal models of FMCW CSAR in the time domain and wavenumber domain are first derived in this work. Then, the signal characteristics including the two-dimensional (2-D) wavenumber spectrum, the spectrum support region, the point spread function, and the resolution are analyzed. Moreover, the effects of intra-pulse movement are analyzed, including the range offset error, the main lobe broadening, and the additional phase error in the range dimension, as well as the extra first-order and second-order phase errors in the 2-D wavenumber domain. Based on the intra-pulse motion analysis, two criterions are provided to determine whether the intra-pulse movement of FMCW CSAR is negligible. An improved back projection (BP) algorithm compensating the intra-pulse motion in the range domain and another algorithm combining the traditional BP and compensation the intra-pulse motion in the wavenumber domain are proposed. Simulation results verify the correctness of the FMCW CSAR signal characteristics analysis and the effectiveness of the intra-pulse movement compensation methods.

外文数据库

氯化锂和六氟磷酸锂与吡啶和乙烯基吡啶的溶剂合物的盐的结构和结构比较：（C5 H5 N）LiPF6，[p-（CH2=CH）C5 H4 N]LiPF6、[（C5 H5N）LiCl]N和[p-（C2

Duetotheflammabilityofliquidelectrolytesusedinlithiumionbatteries,solidlithiumionconductorsareofinteresttoreducedangerandincreasesafety.Thetwodominatinggeneralclassesofelectrolytesunderexplorationasalternativesareceramicandpolymerelectrolytes.Ourgrouphasbeenexploringthepreparationofmolecularsolvatesoflithiumsaltsasalternatives.DissolutionofLiClorLiPF6inpyridine(py)orvinylpyridine(VnPy)andslowvapordiffusionwithdiethylethergivessolvatesofthelithiumsaltscoordinatedbypyridineligands.ForLiPF6,thesolvatesformedinpyridineandvinylpyridine,namelytetrakis(pyridine-κN)lithium(I)hexafluorophosphate,[Li(C5H5N)4]PF6,andtetrakis(4-ethenylpyridine-κN)lithium(I)hexafluorophosphate,[Li(C7H7N)4]PF6,exhibitanalogousstructuresinvolvingtetracoordinatedlithiumionswithneighboringPF6−anionsintheIandAea2spacegroups,respectively.ForLiClsolvates,twoverydifferentstructuresform.catena-Poly[[(pyridine-κN)lithium]-μ3-chlorido],[LiCl(C5H5N)]n,crystalizesintheP212121spacegroupandcontainschannelsofedge-fusedLiClrhombstemplatedbyrowsofπ-stackedpyridineligands,whilethestructureoftheLiCl–VnPysolvate,namelydi-μ-chlorido-bis[bis(4-ethenylpyridine-κN)lithium],[Li2Cl2(C7H7N)4],isdescribedintheP21/nspacegroupasdinuclear(VnPy)2Li(μ-Cl)2Li(VnPy)2unitspackedwithneighborsviaadensearrayofπ–πinteractions.

外文数据库

几何复杂环境中的质量感知无人机覆盖范围和路径规划

Networks of unmanned aerial vehicles (UAVs), capable of providing flexible aerial views over large areas, are playing important roles in today’s distributed sensing systems. Since camera sensors are sensitive to occlusions, it is more challenging for UAVs to provide satisfactory sensing quality in geometrically complex environments, such as dense urban areas and mountainous terrains. This paper proposes a new quality-aware and energy-efficient UAV coverage and path planning scheme with the objective of sensing a geometrically complex target area with satisfactory spatial and temporal resolutions. An occlusion-aware waypoint generation algorithm is first designed to find the best set of waypoints for taking pictures in a target area to satisfy the spatial resolution requirement. The selected waypoints are then assigned to multiple UAVs by solving a vehicle routing problem (VRP) such that all the waypoints are visited within a global deadline to satisfy the temporal resolution requirement. The vehicle routing problem is formulated to minimize the maximum energy for the UAVs to travel through the waypoints within the deadline. A Min-Max energy path planning algorithm is designed to solve this problem in two steps: first, a mixed integer linear programming problem (MILP) is solved to calculate the minimum energy for a UAV to go from one waypoint to other; then, a genetic algorithm is devised to plan the paths for all the UAVs. Evaluation results show that the proposed coverage and path planning scheme results in better coverage and energy consumption than traditional coverage and path planning techniques for UAVs.

外文数据库

使用无人机和声频域分析进行风力涡轮机声学检查

Wind energy has supposed an important technological evolution in the last years in machinery advances and modern materials. Nevertheless, maintenance management and failure detection techniques require advances analytics. This article presents a new approach for wind turbines noise patterns using a deep acoustic analysis developed in the field on frequency domain. It is presented a new condition monitoring system embedded in an Unmanned Aerial Vehicle with an acoustic sensor. The validation is performed in a laboratory test rig and a real case study is also presented. The results obtained from the signal processing provide the detection and identification of faults in frequency domain analysis, making possible a dissertation between scenarios. This evidence keeps open the future research about sound analytics methodology for the wind turbines maintenance.

外文数据库

步行速度和身体机能短与转变为长期护理需求有关：一项针对机车综合征-虚弱诊所门诊患者的研究

外文数据库

利用无人驾驶飞行器和三维场景重建对桥梁码头进行基于图像的快速评估

Crack assessment of bridge piers using unmanned aerial vehicles (UAVs) eliminates unsafe factors of manual inspection and provides a potential way for the maintenance of transportation infrastructures. However, the implementation of UAV‐based crack assessment for real bridge piers is hindered by several key issues, including the following: (a) both perspective distortion and the geometry distortion by nonflat structural surfaces usually appear on crack images taken by the UAV system from the pier surface; however, these two kinds of distortions are difficult to correct at the same time; and (b) the crack image taken by a close‐range inspection flight UAV system is partially imaged, containing only a small part of the entire surface of the pier, and thereby hinders crack localization. In this paper, a new image‐based crack assessment methodology for bridge piers using UAV and three‐dimensional (3D) scene reconstruction is proposed. First, the data acquisition of UAV‐based crack assessment is discussed, and the UAV flight path and photography strategy for bridge pier assessment are proposed. Second, image‐based crack detection and 3D reconstruction are conducted to obtain crack width feature pair sequences and 3D surface models, respectively. Third, a new method of projecting cracks onto a meshed 3D surface triangular model is proposed, which can correct both the perspective distortion and geometry distortion by nonflat structural surfaces, and realize the crack localization. Field test investigations of crack assessment of a real bridge pier using a UAV are carried out for illustration, validation, and error analysis of the proposed methodology.

外文数据库

注意控制措施提高军队职业能力测验的有效性

WeevaluatedthepredictivevalueoftheArmedServicesVocationalAptitudeBattery(ASVAB)atthelatentlevel,usingmultitaskingasaproxyforreal-worldjobperformance.WealsoexaminedwhetheraddingmeasuresofattentioncontroltotheASVABcouldimproveitspredictivevalidity.Toanswerthesequestions,datawerecollectedfrom171youngadultsrecruitedfromtheGeorgiaInstituteofTechnologyandthegreaterAtlantacommunity.BothregressionandlatentvariableanalysesrevealedthattheASVABdoespredictmultitaskingatthelatentlevelbutthatmeasuresofattentioncontroladdsubstantialpredictivevalidityinexplainingmultitaskingaboveandbeyondtheASVAB,fluidintelligence,andprocessingspeed.Theoreticalaswellaspracticalapplicationsoftheseresultsarediscussedintermsoftheoriesofattentioncontrol,andpotentialcostsavingsinselectionformilitarypositions."

外文数据库

三层SiO2@PI/m-PE/SiO2@PI纳米纤维复合膜实现高性能、高安全性的锂离子电池隔膜

Inthecurrentstudy,anovelneedlelesselectro-spinneretbasedontheVonKochcurveofFractalTheoryisdevelopedtoprepareelectrospunmembrane.Asandwich-likecompositeseparatoriselaboratelydesignedwithtwolayersofSiO2nanoparticlesdopedpolyimidemembranesbeingthesheathlayersandasinglelayerofethylcellulosemodifiedPEmembranebeingcorelayertowardsitsapplicationforseparatorsinhigh-performancelithium-ionbatteries.Thistri-layeredcompositeseparatorcombinesboththermalshutdownfunctionatlowtemperatureandthermalrunawayfunctionathightemperature,whereethylcelluloseisusedtoenhancetheinterfacialaffinityandstrengthbetweencommercialpolyethyleneseparatorandtheelectrospunpolyimidemembrane.ThetwosheathlayersofelectrospunmembranepreparedbySiO2nanoparticlesdopedpolyimideimparttheseparatorwithhighthermalstabilityandhigh-temperaturerunawayfunctionat,andthesinglecorelayerofethylcellulosemodifiedpolyethylenemembraneprovideshighmechanicalpropertyandlow-temperatureshutdownfunction.Theresultanttri-layeredcompositemembraneisofhighpotentialaslithium-ionbatteryseparatorsforelectricallypoweredvehicles.

外文数据库

网络编码无人机综合系统安全研究

Since the great ability of integration and proactive mobility, unmanned aerial vehicle (UAV) has been hot spot resent years. Motivated by the evolving requirements for monitoring and data collection, UAV has been considered as a part of collaborative, hybrid system called UAV integrated system which generates great benefits for the whole system. Due to the fragile of the nature of wireless transmission in UAV integrated system, the security of UAV integrated system becomes the real challenge in practice. It has been discussed in the perspective of physical layer security. However, the solutions usually involve two shortcomings in practice: the knowledge of the location of the eavesdropper has to be given as precondition, which is in contrast to the fact that the eavesdropper must hide itself properly; the other one is that non-convex problems are reduced to search the UAV trajectory for avoiding eavesdropper, it is not hard to see that non-convex optimization involves much computation while the consumption of power of UAV is critical in practice. In this paper, we propose a new strategy to deal with the security of UAV integrated system based on network coding such that the system doesn't need extra knowledge of eavesdropper and new solution indicates a linear algorithm which is more suitable to the demand of power consumption of UAV than non-convex optimization.

外文数据库

电池活性氧化镍调查第一季度报告

外文数据库

大豆分离蛋白和蒙脱石对聚合物电解质与全固态锂离子电池电极界面稳定性的协同作用

Inresponsetothesafetyperformanceofliquidelectrolytesintraditionallithium-ionbatteries,wehavepreparedanewtypeofpolymerelectrolyte.Inthispaper,PVDFisusedasthepolymerelectrolytematrix,bio-basedfillersoybeanproteinisolate(SPI),andinorganicfillermontmorillonite(MMT)asadditionalgroups.Inaddition,theeffectsoftheadditionofsoybeanproteinisolate(SPI)andmontmorillonite(MMT)onthepolymerelectrolyteionconductivity,lithiumionmigrationnumber,andelectrodeinterfaceperformancewereinvestigated.Afterthetest,itwasfoundthatthepolymerelectrolytemembranewithMMTandSPIhadanionconductivityof2.56×10?4Scm?1atroomtemperature,anelectrochemicalstabilitywindowof5.1V,andaLi+transfernumberof0.77.WhenassemblingLi/LiTFSI-MMT-SPI-PVDF/Libatteries,thesymmetricbatteryhasastableelectrodeinterfacebecauseitcancirculatestablyformorethan100hataverysmallpolarizationvoltage.GraphicalAbstract

外文数据库

锂离子电池的在线充放电控制

外文数据库

考虑风电和光伏发电相关性和随机性的混合能源微电网优化配置

Inthisstudy,animprovedmethodofoptimalsizingmethodforahybrid-energymicrogrid(HEM)isproposed,simultaneouslyconsideringtheimpactofcorrelationandrandomnessofthewindpowerandphotovoltaic(PV)poweronHEM'ssizing.Theproposedoptimalsizingmethodisbasedonthefollowingsteps:firstly,inordertoobtainalargeamountofdataforthewindpowerandPVpowerintheplannedarea,acombinedmethodwhichincludesKendallrankcorrelationcoefficient,non-parametricestimation,CopulatheoryandMonteCarloisproposedtogeneratethejointprobabilitydensityfunctionofthewindpowerandPVpowerandtogenerateanamountofdata.Then,whileguaranteeingreliablesystemoperationofenergysupply,theoptimalsizingobjectivefunctionwithaminimumofoperationcost,investmentcostandpollutiongastreatmentcostisestablishedbasedonthescenario-basedapproach.Finally,acasestudyofHEMispresentedtoverifytheadvantagesoftheproposedoptimalsizingmethod.

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