Flapping-Wing Air Vehicles(FWAVs)have been developed to pursue the efficient,agile,and quiet flight of flying ***,unlike lightweight FWAVs capable of vertical takeoff,relatively heavy FWAVs face challenges in self-tak...
详细信息
Flapping-Wing Air Vehicles(FWAVs)have been developed to pursue the efficient,agile,and quiet flight of flying ***,unlike lightweight FWAVs capable of vertical takeoff,relatively heavy FWAVs face challenges in self-takeoff,which refers to taking off without both external device and energy *** this study,a cliff-drop method is implemented for an independent takeoff of a heavy FWAV,relying solely on *** the takeoff process using the cliff-drop method,the FWAV moves on the ground to a cliff edge using a wheel-driving motor and then descends from the cliff to achieve the necessary speed for *** demonstrate the cliff-drop method,the KAIST Robotic Hawk(KRoHawk)with a mass of 740 g and a wingspan of 120 cm is *** takeoff tests demonstrate that the KRoHawk,significantly heavier than the vertical-takeoff capable FWAVs,can successfully take off using the gravity-assisted takeoff *** scalability of cliff-drop method is analyzed through *** drop constraints are absent,the wheel-driving motor mass fraction for cliff-drop method remains negligible even as the vehicle's weight *** drop constraints are set to 4 m,FWAVs heavier than KRoHawk,weighing up to 4.4 kg,can perform the cliff-drop takeoffs with a wheel-driving motor mass fraction of less than 8%.
Augmenting the working voltage is an effective way to maximize the energy density of Ni-rich layered Li[Ni0.8Co0.1Mn0.1]O2（NCM） to approach its theoretical ***,NCM suffers from structural degradation in deep delithi...
详细信息
Augmenting the working voltage is an effective way to maximize the energy density of Ni-rich layered Li[Ni0.8Co0.1Mn0.1]O2（NCM） to approach its theoretical ***,NCM suffers from structural degradation in deep delithiation state,which is often accompanied by severe surface lattice oxygen loss and transition metal dissolution,leading to restricted cycle ***,a facile and effective surfacestrengthening strategy is proposed,in which Mn（OH）2nanoshells are uniformly grown on the NCM surface as a Li+capturer and then converted to thin spinel Li4Mn5O12layers during subsequent hightemperature *** resultant Li4Mn5O12layers can enhance cathode-electrolyte interface electrochemical stability with inhibited electrolyte corrosion and accelerated Li+*** theoretical calculations confirms that the Mn-O bonds formed at the interfaces can effectively decrease the oxygen activity,thereby further inhibiting the lattice oxygen release and structural degradation caused by the irreversible phase ***,the Li4Mn5O12-coated NCM displays high capacity retention of 80.3% and 94.9% at 1 C and 5 C compared to the pristine NCM（52.5% and 10.1%） after 200 cycles and can operate stably at 2.7-4.6 V and 60℃.The spinel Li4Mn5O12-coating demonstrates an effective route to enhance the structural/electrochemical stability of NCM for next-generation advanced lithium-ion batteries.
The virtual private cloud service currently lacks a real-time end-to-end consistency validation mechanism, which prevents tenants from receiving immediate feedback on their requests. Existing solutions consume excessi...
详细信息
The virtual private cloud service currently lacks a real-time end-to-end consistency validation mechanism, which prevents tenants from receiving immediate feedback on their requests. Existing solutions consume excessive communication and computational resources in such large-scale cloud environments, and suffer from poor timeliness. To address these issues, we propose a lightweight consistency validation mechanism that includes real-time incremental validation and periodic full-scale validation. The former leverages message layer aggregation to enable tenants to swiftly determine the success of their requests on hosts with minimal communication overhead. The latter utilizes lightweight validation checksums to compare the expected and actual states of hosts locally, while efficiently managing the checksums of various host entries using inverted indexing. This approach enables us to efficiently validate the complete local configurations within the limited memory of hosts. In summary, our proposed mechanism achieves closed-loop implementation for new requests and ensures their long-term effectiveness.
Weathering steel exhibits excellent corrosion resistance and is widely used in bridges,towers,railways,highways,and other engineering projects that are exposed to the atmosphere for long periods of ***,before the form...
详细信息
Weathering steel exhibits excellent corrosion resistance and is widely used in bridges,towers,railways,highways,and other engineering projects that are exposed to the atmosphere for long periods of ***,before the formation of stable rust layers,weathering steel is prone to liquid rust sagging and spattering,leading to environmental pollution and city appearance *** factors limit the application and development of weathering *** this study,a rapid and environmentally friendly method was de-veloped by introducing alloying elements,specifically investigating the role of Sn in the rapid stabilization of rust layers in marine atmo-spheric *** rust layer formed on weathering low-alloy steel exposed to prolonged outdoor conditions and laboratory im-mersion experiments was explored using electron probe micro-analyzer(EPMA),micro-Raman,X-ray photoelectron spectroscopy(XPS),and electrochemical *** showed an optimal synergistic effect between Sn and Cr,which facilitated the accelerated densification of the rust *** beneficial effect enhanced the capability of the rust layer to resist Cl^(-)erosion and improved the protec-tion performance of the rust layer.
Based on the principles of thermodynamics, we elucidate the fundamental reasons behind the hysteresis of spontaneous polarization in ferroelectric materials during heating and cooling processes. By utilizing the effec...
详细信息
Based on the principles of thermodynamics, we elucidate the fundamental reasons behind the hysteresis of spontaneous polarization in ferroelectric materials during heating and cooling processes. By utilizing the effective Hamiltonian method in conjuction with the phase-field model, we have successfully reproduced the thermal hysteresis observed in ferroelectric materials during phase transitions. The computational results regarding the electrocaloric effect from these two different computational scales closely align with experimental measurements. Furthermore, we analyze how the first-order ferroelectric phase transition gradually diminishes with an increasing applied electric field, exhibiting characteristics of second-order-like phase transition. By employing the characteristic parameters of thermal hysteresis, we have established a pathway for calculations across different computational scales, thereby providing theoretical support for further investigations into the properties of ferroelectric materials through concurrent multiscale simulations.
With the rapid advancement of AI technology, there has been a substantial surge in the need for computational resources. Particularly in deep learning, machine learning, and large-scale data analysis, the processing o...
详细信息
Seawater is the most abundant source of molecular *** the hydrogen reserves present in the seawater may inaugurate innovative strategies aimed at advancing sustainable energy and environmental preservation endeavors i...
详细信息
Seawater is the most abundant source of molecular *** the hydrogen reserves present in the seawater may inaugurate innovative strategies aimed at advancing sustainable energy and environmental preservation endeavors in the ***,there has been a surge in study in the field addressing the production of hydrogen through the electrochemical seawater splitting.
Microalloying addition plays a significant role in controlling the characteristics of precipitates in Al *** study investigates the effects of Ag and Sc microalloying addition on the thermal stability of Al-Zn-Mg-Cu a...
详细信息
Microalloying addition plays a significant role in controlling the characteristics of precipitates in Al *** study investigates the effects of Ag and Sc microalloying addition on the thermal stability of Al-Zn-Mg-Cu alloys,via differential scanning calorimetry,transmission electron microscopy,and atom-probe *** results demonstrate that Ag and Sc additions increase the number density of η-MgZn2 type nano-precipitates(formed during heat treatment)by forming direct(Mg-Ag phase,prototype of precipitate)or indirect precursors(Al2Sc phase,constituent of precipitate)for the *** addition,the Ag and Sc elements can effectively prevent the coarsening of η precipitates and facilitate the high-density distribution of fine η precipitates,during the over-aging period,improving the thermal stability of the Al-Zn-Mg-Cu *** thermal stability is particularly improved by Ag addition because Ag atoms directly prevent the coarsening of η precipitates by hindering Zn diffusion into the *** the contrary,Sc addition indirectly prevents the coarsening of η precipitates by depleting the solute species from the Al matrix,enabling abundant precipitates limited *** Ag addition improves precipitation strengthening by preventing the coarsening of precipitates during over-aging.
There remains debate on whether Mn is beneficial or detrimental to hydrogen embrittlement in stainless *** this work,a series of stainless steels were designed to study the change of hydrogen embrit-tlement sensitivit...
详细信息
There remains debate on whether Mn is beneficial or detrimental to hydrogen embrittlement in stainless *** this work,a series of stainless steels were designed to study the change of hydrogen embrit-tlement sensitivity,crack propagation,and hydrogen trapping behaviors upon Mn *** results suggest that adding 4 wt.％Mn increased hydrogen embrittlement susceptibility,whereas adding 8 wt.％Mn decreased hydrogen embrittlement *** banded α'-martensite through austenitic grain is the main reason for the increased hydrogen embrittlement sensitivity when adding 4 wt.％Mn,by ad-sorbing hydrogen,promoting crack initiation,and accelerating crack propagation.
暂无评论