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Preparation and evaluation of α-Al2O3 supported lithium ion sieve membranes for Li^+ extraction

Chinese Journal of Chemical Engineering 2020年第9期28卷 2312-2318页

作者： Feng Xue Xiaoxian Zhang Yue Niu Chenhao yi Shengui Ju Weihong Xing College of Chemical Engineering Nanjing Tech UniversityNanjing 211816China

Spinel lithium manganese oxide ion-sieves have been considered the most promising adsorbents to extract Li^+ from brines and sea ***,we report a lithium ion-sieve which was successfully loaded onto tubular α-Al2 O3 ceramic substrates by dipping crystallization and post-calcination *** lithium manganese oxide Li4 Mn5 O(12)was first synthesized onto tubular α-Al2 O3 ceramic substrates as the ion-sieve precursor(i.e.L-AA),and the corresponding lithium ion-sieve(i.e.H-AA) was obtained after acid *** chemical and morphological properties of the ion-sieve were confirmed by X-ray diffraction(XRD) and scanning electron microscopy(SEM).Both L-AA and H-AA showed characteristic peaks of α-Al2 O3 and cubic phase Li4 Mn5 O(12) and the peaks representing cubic phase could still exist after *** lithium manganese oxide Li4 Mn5 O(12) could be uniformly loaded not only on the surface of α-Al2 O3 ubstrates but also inside the ***,we found that the equilibrium adsorption capacity of H-AA was 22.9 mg·g^-*** 12 h adsorption,the adsorption balance was *** 5 cycles of adsorption,the adsorption capacity of H-AA was 60.88% of the initial adsorption *** process of H-AA adsorption for Li^+correlated with pseudo-second order kinetic model and Langmuir *** thermodynamic parameters regarding enthalpy(△N), Gibbs free energy(△G) and entropy(AS) were *** the dynamic adsorptiondesorption process of H-AA,the H-AA exhibited excellent adsorption performance to Li^+ with the Li^+ dynamic adsorption capacity of 9.74 mg·g^-1 and the Mn^2+dissolution loss rate of 0.99%.After 3 dynamic adsorption-desorption cycles,80% of the initial dynamic adsorption capacity was still kept.

关键词： Lithium α-Al2O3 tube Ion sieve Adsorption Li4Mn5O(12)

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Experimental realization of nonadiabatic geometric gates with a superconducting Xmon qubit

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Science China(Physics,Mechanics & Astronomy) 2021年第5期64卷 2-9页

作者： PeiZi Zhao ZhangJingZi Dong ZhenXing Zhang GuoPing Guo DianMin Tong yi yin Deparment of Physies Shandong Universiry Jinan 250100 China Department of Physics Zhejiang UniversityHangzhou 310027China Key Labortlory of Quanwum Information University of Science and Technology of ChinaHefei 230026China Origin Quantum Computing Hefei 230026China

Geometric phases are only dependent on evolution paths but independent of evolution details so that they possess some intrinsic noise-resilience features. Based on different geometric phases, various quantum gates have been proposed, such as nonadiabatic geometric gates based on nonadiabatic Abelian geometric phases and nonadiabatic holonomic gates based on nonadiabatic nonAbelian geometric phases. Up to now, nonadiabatic holonomic one-qubit gates have been experimentally demonstrated with superconducting transmons, where the three lowest levels are all utilized in operation. However, the second excited state of transmons has a relatively short coherence time, which results in a decreased fidelity of quantum gates. Here, we experimentally realize Abelian-geometric-phase-based nonadiabatic geometric one-qubit gates with a superconducting Xmon qubit. The realization is performed on the two lowest levels of an Xmon qubit and thus avoids the influence from the short coherence time of the second excited state. The experimental result indicates that the average fidelities of single-qubit gates can be up to 99.6% and 99.7% characterized by quantum process tomography and randomized benchmarking.

关键词： geometric phases geometric quantum computation superconducting qubit

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Extracting embedded messages using adaptive steganography based on optimal syndrome-trellis decoding paths

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Digital Communications and Networks 2022年第4期8卷 455-465页

作者： Jialin Li Xiangyang Luo yi Zhang Pei Zhang Chunfang Yang Fenlin Liu State Key Laboratory of Mathematical Engineering and Advanced Computing Zhengzhou450000China

Privacy protection is the key to maintaining the Internet of Things(IoT)communication *** is an important way to achieve covert communication that protects user data *** technology is the key to checking steganography security,and its ultimate goal is to extract embedded *** methods cannot extract under known cover *** this end,this paper proposes a method of extracting embedded messages under known cover ***,the syndrome-trellis encoding process is ***,a decoding path in the syndrome trellis is obtained by using the stego sequence and a certain parity-check matrix,while the embedding process is simulated using the cover sequence and parity-check *** the decoding path obtained by the stego sequence and the correct parity-check matrix is optimal and has the least distortion,comparing the path consistency can quickly filter the coding parameters to determine the correct matrices,and embedded messages can be extracted *** proposed method does not need to embed all possible messages for the second time,improving coding parameter recognition *** experimental results show that the proposed method can identify syndrome-trellis coding parameters in stego images embedded by adaptive steganography quickly to realize embedded message extraction.

关键词： Information security Image steganography STC coding Parameter recognition

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Scene-adaptive crowd counting method based on meta learning with dual-input network DMNet

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Frontiers of Computer Science 2023年第1期17卷 91-100页

作者： Haoyu ZHAO Weidong MIN Jianqiang XU Qi WANG yi ZOU Qiyan FU School of Information Engineering Nanchang UniversityNanchang 330031China School of Software Nanchang UniversityNanchang 330047China Jiangxi Key Laboratory of Smart City Nanchang 330047China

Crowd counting is recently becoming a hot research topic, which aims to count the number of the people in different crowded scenes. Existing methods are mainly based on training-testing pattern and rely on large data training, which fails to accurately count the crowd in real-world scenes because of the limitation of model’s generalization capability. To alleviate this issue, a scene-adaptive crowd counting method based on meta-learning with Dual-illumination Merging Network (DMNet) is proposed in this paper. The proposed method based on learning-to-learn and few-shot learning is able to adapt different scenes which only contain a few labeled images. To generate high quality density map and count the crowd in low-lighting scene, the DMNet is proposed, which contains Multi-scale Feature Extraction module and Element-wise Fusion Module. The Multi-scale Feature Extraction module is used to extract the image feature by multi-scale convolutions, which helps to improve network accuracy. The Element-wise Fusion module fuses the low-lighting feature and illumination-enhanced feature, which supplements the missing illumination in low-lighting environments. Experimental results on benchmarks, WorldExpo’10, DISCO, USCD, and Mall, show that the proposed method outperforms the existing state-of-the-art methods in accuracy and gets satisfied results.

关键词： crowd counting meta-learning scene-adaptive Dual-illumination Merging Network

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Service-based Reliability Analysis of Integrated Electricity-heat Systems Considering Thermal Dynamics

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Journal of Modern Power Systems and Clean Energy 2023年第4期11卷 1176-1190页

作者： Xunhu yin Minglei Bao yi Ding Chengjin Ye Peng Wang Lalit Goel College of Electrical Engineering Zhejiang UniversityHangzhou 310027China Electrical and Electronic Engineering School Nanyang Technological UniversitySingapore 639798

The essential task of integrated electricity-heat systems(IEHSs)is to provide customers with reliable electric and heating *** the perspective of customers,it is reasonable to analyze the reliabilities of IEHSs based on the ability to provide energy services with a reasonable assurance of continuity and quality,which are termed as service-based *** to the thermal inertia existing in IEHSs,the heating service performances can present slow dynamic characteristics,which has a great impact on the service satisfaction of *** neglect of such thermal dynamics will bring about inaccurate service-based reliability measurement,which can lead to the inefficient dispatch decisions of system ***,it is necessary to provide a tool which can analyze the servicebased reliabilities of IEHSs considering the impacts of thermal *** paper firstly models the energy service performance of IEHSs in contingency ***,the nodal energy supplies are obtained from the optimal power and heat flow model under both variable hydraulic and thermal conditions,in which the transmission-side thermal dynamics are *** this basis,the energy service performances for customers are further determined with the formulation of demandside thermal ***,a service-based reliability analysis framework for the IEHSs is proposed utilizing the timesequential Monte Carlo simulation(TSMCS)technique with the embedded decomposition ***,the indices for quantifying service-based reliabilities are defined based on the traditional reliability indices,where dynamic service performances and service satisfactions of customers are both *** simulations are carried out with a test system to validate the effectiveness of the proposed framework.

关键词： Energy service integrated electricity-heat system reliability thermal dynamics

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Highly coordinated Pd overlayers on nanoporous gold for efficient formic acid electro-oxidation

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Nano Research 2021年第10期14卷 3502-3508页

作者： Qinqin Sang Shuai yin Feng Liu Huiming yin Jia He yi Ding Tianjin Key Laboratory of Advanced Functional Porous Materials Institute for New Energy Materials&Low-Carbon TechnologiesSchool of Materials Science and EngineeringTianjin University of TechnologyTianjin 300384China Kunming Institute of Precious Metals Kunming 650106China

Design and fabrication of highly efficient and stable electrocatalysts remain key challenges in green energy technologies such as low-temperature direct liquid fuel *** on in-depth theoretical calculations,here we demonstrate that surface Pd atoms with high coordination numbers(HCNs)can effectively modulate their adsorption energies for CO and OH,and thus achieve very high performance for formic acid electro-oxidation reaction(FAOR).Based on epitaxial coating Pd atomic layers onto nanoporous gold(NPG)thin membranes and a slight further decoration of Au clusters on top,the resulted core-shell structured NPG-Pd-Au electrocatalyst can demonstrate Pd intrinsic and mass activities of 8.62 mA·cm^(-2)and 27.25 A·mg^(-1)respectively at the peak potential around 0.33 V versus saturated calomel electrode toward FAOR,which are far better than those of commercial Pd/C catalysts(1.09 mA·cm^(-2)and 0.32 A·mg^(-1))tested under the same ***,the membrane electrode assemblies based on these low precious metal loading electrodes can achieve an anode Pd power efficiency over 10 W·mg^(-1)in a direct formic acid fuel cell,which is two orders of magnitude higher than that of the commercial Pd/*** results provide new inspirations for the development of revolutionary electrodes for energy technologies in a rational manner.

关键词： Pd nanoporous gold high coordination number formic acid oxidation direct formic acid fuel cell

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Experimental investigation of expansion effect on shock wave boundary layer interaction near a compression ramp

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Chinese Journal of Aeronautics 2022年第12期35卷 89-101页

作者： Junjie HUO Shihe yi Wenpeng ZHENG Haibo NIU Xiaoge LU Dundian GANG College of Aerospace Science and Engineering National University of Defense TechnologyChangsha 410073China

The experiment is conducted to investigate the effect of expansion on the shock wave boundary layer interaction near a compression ramp. The small-angle expansion with an angle degree of 5° occurs at different positions in front of the compression ramp. The particle image velocimetry and flow visualization technology show the flow structures, velocity field, and velocity fluctuation near the compression ramp. The mean pressure distribution, pressure fluctuation, and power spectral density are measured by high-frequency response pressure transducers. The experimental results indicate that the expansion before the compression ramp position affects the shock wave boundary layer interaction to induce a large-scale separation. But the velocity fluctuation and pressure fluctuation are attenuated near the large-scale flow separation region. When the expansion occurs closer to the compression ramp, the expansion has a more significant impact on the flow. The fluctuation of velocity and pressure is significantly attenuated, and the wall pressure rise of the separation point is reduced obviously. And the characteristic low-frequency spectrum signal related to the unsteadiness of the shock wave boundary layer interaction is significantly suppressed. In addition, variation of the separation region scale at different compression angle degrees is distinctive with the effect of expansion.

关键词： Boundary layers Flow visualization Fluid dynamic Pressure measurement Shock waves Supersonic aerodynamics Velocity measurement

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Underwater Laser Welding/Cladding for High-performance Repair of Marine Metal Materials:A Review

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Chinese Journal of Mechanical Engineering 2022年第1期35卷 31-49页

作者： Guifang Sun Zhandong Wang yi Lu Mingzhi Chen Kun Yang Zhonghua Ni School of Mechanical Engineering Jiangsu Key Laboratory for Design and Manufacture of Micro-Nano Biomedical InstrumentsSoutheast UniversityNanjing 211189China

With the rapid developments of marine resource exploitation,mounts of marine engineering equipment are settled on the *** it is not possible to move the damaged equipment into a dry dock,welding operations must be performed in underwater *** underwater laser welding/cladding technique is a promising and advanced technique which could be widely applied to the maintenance of the damaged *** present review paper aims to present a critical analysis and engineering overview of the underwater laser welding/cladding ***,we elaborated recent advances and key issues of drainage nozzles all over the ***,we presented the underwater laser processing and microstructural-mechanical behavior of repaired marine ***,the newly developed powder-feeding based and wire-feeding based underwater laser direct metal deposition techniques were *** differences between the convection,conduction,and the metallurgical kinetics in the melt pools during underwater laser direct metal deposition and in-air laser direct metal deposition were *** that,several challenges that need to be overcame to achieve the full potential of the underwater laser welding/cladding technique are ***,suggestions for future directions to aid the development of underwater laser welding/cladding technology and underwater metallurgical theory are *** present review will not only enrich the knowledge in the underwater repair technology,but also provide important guidance for the potential applications of the technology on the marine engineering.

关键词： Underwater laser welding Underwater laser direct metal deposition Drainage nozzle Marine metal materials Mechanical property Diffusible hydrogen

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Effect of cyclic wetting-drying on tensile mechanical behavior and microstructure of clay-bearing sandstone

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International Journal of Coal Science & Technology 2021年第5期8卷 956-968页

作者： Pingye Guo Juan Gu yi Su Jiong Wang Zhanwen Ding State Key Laboratory for Geo-Mechanics and Deep Underground Engineering Beijing 100083China School of Mechanics Architecture and Civil EngineeringChina University of Mining and TechnologyBeijing 100083China Tang Steel International Engineering Technology Corp Tangshan 063000China China Henan Geological and Mineral Resources Construction Engineering(Group)Co. LtdZhengzhou 450007China

The understanding of the weakening mechanism of tensile strength of rock subjected to cyclic wetting-drying is critical for rock *** strength tests were conducted on a total of 35 sandstone specimens with different wetting-drying *** crack propagation process and acoustic emission characteristics of the tested samples were obtained through a high-speed camera and acoustic emission *** results indicate that the tensile strength is observably reduced after cyclic wetting-drying,and the extent of the reduction is not only related to the number of wettingdrying cycle,but also closely related to the clay mineral content of the *** addition,as the cycles of wetting-drying increase,the effect of each single cycle on tensile strength get reduced until it becomes ***,the crack initiation and penetration time is prolonged as the number of wetting-drying cycle increases,which indicates that cyclic wetting-drying weakens the rock stiffness and enhances the ductility of ***,the acoustic emission characteristics of the tested samples further confirmed the ductile behaviour of the sandstone samples with increasing wetting-drying ***,through the analysis of the microstructure and mineral composition of the samples with different wetting-drying cycles,it is concluded that the main weakening mechanisms of sandstones containing clay minerals are frictional reduction,chemical and corrosive deterioration.

关键词： Sandstone Wetting-drying cycle Tensile strength Weakening mechanism Failure characteristics

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Two-dimensional molybdenum carbide(MXene)as an efficient nanoadditive for achieving superlubricity under ultrahigh pressure

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Friction 2023年第3期11卷 369-382页

作者： Shuang yi yitong GUO Jinjin LI Yuxin ZHANG Aiguo ZHOU Jianbin LUO State Key Laboratory of Tribology Tsinghua UniversityBeijing 100084China College of Materials Science and Engineering Chongqing UniversityChongqing 400044China Henan Key Laboratory of Materials on Deep-Earth Engineering Henan Polytechnic University Jiaozuo 454003China

In this study,a robust macroscale liquid superlubricity with a coefficient of friction of 0.004 was achieved by introducing molybdenum carbide(Mo_(2)CT_(x))MXene nanoparticles as lubricating additives in a lithium hexafluorophosphate-based ionic liquid at Si_(3)N_(4)-sapphire *** maximal contact pressure in the superlubricity state could reach 1.42 GPa,which far exceeds the limit of the superlubricity regime in previous *** results indicate that a composite tribofilm(mainly containing molybdenum oxide and phosphorus oxide)that formed at the interface by a tribochemical reaction contributed to the excellent antiwear ***,the extremely low shear strength of the tribofilm and the interlayers of Mo_(2)CT_(x)MXene contributed to the *** work demonstrates the promising potential of Mo_(2)CT_(x)MXene in improving superlubricity properties,which could accelerate the application of superlubricity in mechanical systems.

关键词： molybdenum carbide(Mo_(2)CT_(x))MXene superlubricity additives ultrahigh pressure wear resistance

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