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Performance analysis and multi-objective optimization based on a modified irreversible Stirling cycle

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Science China(Technological Sciences) 2024年第6期67卷 1668-1684页

作者： XU Lei YU MinJie liu ZhiChun liu wei School of Energy and Power Engineering Huazhong University of Science and TechnologyWuhan430074China

The efficiency of the actual Stirling engine is much lower than the ideal Carnot cycle *** obtain more precise efficiency for Stirling engines,this paper proposes a modified Stirling cycle with a more accurate heat transfer process in Stirling engines based on a thermodynamic function called available *** finite-time thermodynamic method is used to analyze the model performance under constant heat source temperature,finite temperature difference heat transfer,and incomplete regenerative processes.A new polytropic process is introduced to model the heat transfer between the working fluid and external heat sources in which only heat above ambient temperature is converted into technical *** regenerator is divided into numerous smaller heat reservoirs with individual temperature to analyze the incomplete regenerative *** expressions of the output power and thermal efficiency are obtained based on the modified irreversible Stirling cycle,and the effects of irreversible losses are analyzed to evaluate the performance of the proposed *** indicate that the efficiency of the modified cycle is much lower than that of the ideal Stirling cycle with an isothermal *** the increase of the average heat transfer temperature difference,there exists an optimum value for the power of the irreversible *** optimum power of the model was obtained for varying thermodynamic parameters by optimizing the average heat transfer temperature difference between the hot and cold *** optimize the irreversible model,the multi-objective optimization analysis is carried out based on NSGA-Ⅱ,which results in an optimized output power of 40.87 kW and an optimized thermal efficiency of 44%.

关键词： stirling cycle regenerative processes isopotential processes multi-objective optimization finite time thermodynamics

Interfacial Oxygen Octahedral Coupling-Driven Robust Ferroelectricity in Epitaxial Na_(0.5)Bi_(0.5)TiO_(3)Thin Films

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Research 2024年第2期2023卷 149-157页

作者： Haojie Han Qinghua Zhang wei Li Yiqun liu Jiasheng Guo Yue Wang Qian Li Lin Gu Ce-Wen Nan jing Ma State Key Laboratory of New Ceramics and Fine Processing Schoolof Materials Science and EngineeringTsinghua UniversityBeijing 100084China Beijing National Laboratory for Condensed Matter Physics Institute of PhysicsChinese Academy of SciencesBeijing 100190China

The oxygen octahedral rotation(OOR)forms fundamental atomic distortions and symmetries in perovskite oxides and definitely determines their properties and ***,epitaxial strain and interfacial structural coupling engineering have been developed to modulate the OOR patterns and explore novel properties,but it is difficult to distinguish the 2 ***,different symmetries are induced in Na_(0.5)Bi_(0.5)TiO_(3)(NBT)epitaxial films by interfacial oxygen octahedral coupling rather than epitaxial *** NBT film grown on the Nb:SrTiO_(3)substrate exhibits a paraelectric tetragonal phase,while with La_(0.5)Sr_(0.5)MnO_(3)as a buffer layer,a monoclinic phase and robust ferroelectricity are obtained,with a remanent polarization of 42μC cm^(-2)and a breakdown strength of 7.89 MV cm^(-1),which are the highest record among NBT-based ***,the interfacial oxygen octahedral coupling effect is demonstrated to propagate to the entire thickness of the film,suggesting an intriguing long-range *** work provides a deep insight into understanding the structure modulation in perovskite heterostructures and an important avenue for achieving unique functionalities.

关键词： effect. interfacial coupling

Moderate Fields, Maximum Potential: Achieving High Records with Temperature‑Stable Energy Storage in Lead‑Free BNT‑Based Ceramics

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Nano-Micro Letters 2024年第5期16卷 184-200页

作者： Wenjing Shi Leiyang Zhang Ruiyi jing Yunyao Huang Fukang Chen Vladimir Shur Xiaoyong wei Gang liu Hongliang Du Li Jin Electronic Materials Research Laboratory Key Laboratory of the Ministry of EducationSchool of Electronic Science and EngineeringXi’an Jiaotong UniversityXi’an 710049People’s Republic of China School of Materials and Energy Southwest UniversityChongqing 400715People’s Republic of China School of Natural Sciences and Mathematics Ural Federal UniversityEkaterinburg 620000Russia Multifunctional Electronic Ceramics Laboratory College of EngineeringXi’an International UniversityXi’an 710077People’s Republic of China

The increasing awareness of environmental concerns has prompted a surge in the exploration of leadfree,high-power ceramic *** efforts to develop leadfree dielectric ceramics with exceptional energystorage performance(ESP)have predominantly relied on multicomponent composite strategies,often accomplished under ultrahigh electric ***,this approach poses challenges in insulation and system downsizing due to the necessary working voltage under such *** extensive study,bulk ceramics of(Bi_(0.5)Na_(0.5))TiO_(3)(BNT),a prominent lead-free dielectric ceramic family,have seldom achieved a recoverable energy-storage(ES)density(Wrec)exceeding 7 J cm^(−3).This study introduces a novel approach to attain ceramic capacitors with high ESP under moderate electric fields by regulating permittivity based on a linear dielectric model,enhancing insulation quality,and engineering domain structures through chemical formula *** incorporation of SrTiO_(3)(ST)into the BNT matrix is revealed to reduce the dielectric constant,while the addition of Bi(Mg_(2/3)Nb_(1/3))O_(3)(BMN)aids in maintaining ***,the study elucidates the methodology to achieve high ESP at moderate electric fields ranging from 300 to 500 kV cm^(−1).In our optimized composition,0.5(Bi_(0.5)Na_(0.4)K_(0.1))TiO_(3)–0.5(2/3ST-1/3BMN)(B-0.5SB)ceramics,we achieved a Wrec of 7.19 J cm^(−3) with an efficiency of 93.8%at 460 kV cm^(−1).Impressively,the B-0.5SB ceramics exhibit remarkable thermal stability between 30 and 140℃ under 365 kV cm^(−1),maintaining a Wrec exceeding 5 J cm^(−3).This study not only establishes the B-0.5SB ceramics as promising candidates for ES materials but also demonstrates the feasibility of optimizing ESP by modifying the dielectric constant under specific electric field ***,it provides valuable insights for the future design of ceramic capacitors with high ESP under constraints of limited electric field.

关键词： BNT Energy storage Lead-free Relaxor ferroelectrics Capacitors

An efficient parallel algorithm of variational nodal method for heterogeneous neutron transport problems

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Nuclear Science and Techniques 2024年第4期35卷 29-45页

作者： Han Yin Xiao-jing liu Teng-Fei Zhang School of Nuclear Science and Engineering Shanghai Jiao Tong UniversityShanghai 2002040China

The heterogeneous variational nodal method(HVNM)has emerged as a potential approach for solving high-fidelity neutron transport ***,achieving accurate results with HVNM in large-scale problems using high-fidelity models has been challenging due to the prohibitive computational *** paper presents an efficient parallel algorithm tailored for HVNM based on the Message Passing Interface *** algorithm evenly distributes the response matrix sets among processors during the matrix formation process,thus enabling independent construction without *** the formation tasks are completed,a collective operation merges and shares the matrix sets among the *** the solution process,the problem domain is decomposed into subdomains assigned to specific processors,and the red-black Gauss-Seidel iteration is employed within each subdomain to solve the response matrix ***-to-point communication is conducted between adjacent subdomains to exchange data along the *** accuracy and efficiency of the parallel algorithm are verified using the KAIST and JRR-3 test *** results obtained with multiple processors agree well with those obtained from Monte Carlo *** parallelization of HVNM results in eigenvalue errors of 31 pcm/-90 pcm and fission rate RMS errors of 1.22%/0.66%,respectively,for the 3D KAIST problem and the 3D JRR-3 *** addition,the parallel algorithm significantly reduces computation time,with an efficiency of 68.51% using 36 processors in the KAIST problem and 77.14% using 144 processors in the JRR-3 problem.

关键词： Neutron transport Variational nodal method Parallelization KAIST JRR-3

Molecular mechanism of icariin on rat asthmatic model

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Chinese Medical Journal 2011年第18期124卷 2899-2906页

作者： XU Chang-qing LE jing-jing DUAN Xiao-hong DU wei-jing liu Bao-jun WU jing-feng CAO Yu-xue DONG jing-cheng Integrative Department Huashan Hospital Affiliated to FudanUniversity Shanghai 200040 China

Background Effects of icariin on airway inflammation in asthmatic rats and the intervention of LPS induced inflammation are interfered with the machanism of icariin. Our study aimed to observe the effect of icariin on ovalbumin-induced imbalance of Th1/Th2 cytokine expression and its mechanism. Methods Sixty male SD rats were randomly divided into control group （PBS）, asthma group （ovalbumin （OVA）-induced） dexamethasone group, and OVA＋icariin low, medium and high dose groups （5, 10, 20 mg/kg, respectively）. Each group had ten rats. The model of OVA sensitization was a rat asthma model. Enzyme-linked immunosorbent assay （ELISA） method was used to observe the effects of icariin on interleukin-4 （IL-4） and inerferon y （IFN-y） in rats＇ lung tissue. Immunohistochemical staining was applied to detect the intervention effects of icadin on T cells （T-bet） and gatabinding protein 3 （GATA-3） in rat pulmonary tissue. Realtime RT-PCR was used to observe the intervention effects of icariin on T-bet and GATA-3 mRNA expression in rat pulmonary tissue and spleen lymphocytes. Western blotting was used to observe the icariin intervention effects on T-bet, GATA-3 and nuclear factor-Kappa B （NF-KB） p65 protein expressions in rat pulmonary tissue. Results The ELISA results from pulmonary tissue showed that IL-4 expression was significantly reduced （P 〈0.05）, while the IFN-y expression increased but not significantly when we compared OVA＋icariin medium and high dose groups with the asthma group. Immunohistochemical staining of pulmonary tissue showed that the GATA-3 decreased significantly while the T-bet staining did not change in the OVA＋icariin high dose group. In pulmonary tissue and spleen lymphocytes T-bet and GATA-3 mRNA expressions were significantly reduced （P 〈0.05） in icariin treatment groups compared with the asthma model group. GATA-3 and T-bet mRNA in rat spleen lymphocytes in the asthma group were higher than in the control group. GATA-3 mRNA expression in pulmonary tissue

关键词： icariin Th1/Th2 T-bet/GATA-3 nuclear factor Kappa B p65

Applications of in-situ solid-state nuclear magnetic resonance (ssNMR) in methanol to olefins (MTO) reaction

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Science China Chemistry 2024年

作者： jing Niu Shutao Xu Yingxu wei Zhongmin liu National Engineering Research Center of Lower-Carbon Catalysis Technology Dalian Institute of Chemical PhysicsChinese Academy of Sciences State Key Laboratory of Catalysis Dalian Institute of Chemical PhysicsChinese Academy of Sciences University of Chinese Academy of Sciences

The methanol-to-olefins (MTO) reaction offers an alternative pathway for the production of low-carbon olefins from non-oil *** research has been impeded by a lack of comprehensive understanding of its underlying mechanism,despite the significant progress made in ***-situ solid-state nuclear magnetic resonance (ssNMR) spectroscopy has emerged as a pivotal tool,offering crucial insights into key species under real-time operando ***,the host–guest interaction between zeolites or surface species residing on zeolites and the reactant/active intermediates is revealed by the combination of in-situ13C MAS NMR and 2D correlation ***,recent technological advancements in hyperpolarization (HP) methods,including HP129Xe NMR and dynamic nuclear polarization (DNP),have significantly improved the sensitivity of ssNMR,enabling detailed structural and kinetic analysis as well as the detection of trace *** this feature article,we summarized recent advancements in (in-situ) ssNMR spectroscopy applied to MTO reaction processes,encompassing mechanistic investigations at various stages and the intricate host–guest *** theoretical insights into the dynamic evolution of MTO reactions lay a solid foundation for the optimization of catalytic processes and the development of efficient catalysts,thereby advancing the techniques towards more sustainable and economical production route for olefins.

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Improving the spaceborne GNSS-R altimetric precision based on the novel multilayer feedforward neural network weighted joint prediction model

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Defence Technology（防务技术） 2024年第2期32卷 271-284页

作者： Yiwen Zhang wei Zheng Zongqiang liu Qian Xuesen Laboratory of Space Technology China Academy of Space TechnologyBeijing 100094China China Academy of Aerospace Science and Innovation Beijing 100176China State Key Laboratory of Space-Ground Integrated Information Technology Beijing Institute of Satellite Information EngineeringBeijing 100194China

Global navigation satellite system-reflection(GNSS-R)sea surface altimetry based on satellite constellation platforms has become a new research direction and inevitable trend,which can meet the altimetric precision at the global scale required for underwater *** present,there are still research gaps for GNSS-R altimetry under this mode,and its altimetric capability cannot be specifically ***,GNSS-R satellite constellations that meet the global altimetry needs to be ***,the matching precision prediction model needs to be established to quantitatively predict the GNSS-R constellation altimetric ***,the GNSS-R constellations altimetric precision under different configuration parameters is calculated,and the mechanism of the influence of orbital altitude,orbital inclination,number of satellites and simulation period on the precision is analyzed,and a new multilayer feedforward neural network weighted joint prediction model is ***,the fit of the prediction model is verified and the performance capability of the model is tested by calculating the R2 value of the model as 0.9972 and the root mean square error(RMSE)as 0.0022,which indicates that the prediction capability of the model is ***,using the novel multilayer feedforward neural network weighted joint prediction model,and considering the research results and realistic costs,it is proposed that when the constellation is set to an orbital altitude of 500 km,orbital inclination of 75and the number of satellites is 6,the altimetry precision can reach 0.0732 m within one year simulation period,which can meet the requirements of underwater navigation precision,and thus can provide a reference basis for subsequent research on spaceborne GNSS-R sea surface altimetry.

关键词： GNSS-R satellite constellations Sea surface altimetric precision Underwater navigation Multilayer feedforward neural network

Room temperature self-healing liquid metals:capabilities,applications and challenges

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International Journal of Smart and Nano Materials 2024年第3期15卷 469-501页

作者： Chen Hua Jianye Gao jing liu Key Lab of Cryogenic Science and Technology Technical Institute of Physics and ChemistryChinese Academy of SciencesBeijingChina School of Future Technology University of Chinese Academy of SciencesBeijingChina School of Biomedical Engineering Tsinghua UniversityBeijingChina

Self-healing materials span diverse application fields,including flexible electronics,soft robotics,and energy ***,conventional self-healing materials pose a challenge in achiev-ing the delicate balance between flexibility and electrical ***,they also suffer from prolonged healing times,incomplete healing,and high manufacturing *** metals possess excellent self-healing capabilities owing to their unique combination of fluidic and metallic properties,high surface tension,and reversible solid-liquid phase change at room temperature,offering an intriguing material option for addressing the challenges associated with flexibility and elec-trical *** this review article,we comprehensively examine the domain of self-healing liquid metals from the standpoint of typical mechanisms underlying self-healing pro-cesses,as well as practical strategies employed for achieving such ***,we explore representative applications that showcase the potential of these materials while aiming to provide a valuable reference for advancing and enhancing the field of self-healing *** pro-spect along this direction is made.

关键词： Self-healing Liquid metal Smart materials

Suppressing the lattice oxygen diffusion via high-entropy oxide construction towards stabilized acidic water oxidation

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Nano Research 2024年第3期17卷 1107-1113页

作者： jing Ni Zhaoping Shi Yibo Wang Jiahao Yang Hongxiang Wu Pengbo Wang Kai Li Meiling Xiao Changpeng liu wei Xing State Key Laboratory of Electroanalytic Chemistry Jilin Province Key Laboratory of Low Carbon Chemistry PowerChangchun Institute of Applied ChemistryChinese Academy of SciencesChangchun 130022China School of Applied Chemistry and Engineering University of Science and Technology of ChinaHefei 230026China State Key Laboratory of Rare Earth Resource Utilization Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun 130022China

The scale-up deployment of ruthenium(Ru)-based oxygen evolution reaction(OER)electrocatalysts in proton exchange membrane water electrolysis(PEMWE)is greatly restricted by the poor *** the lattice-oxygen-mediated mechanism(LOM)has been identified as the major contributor to the fast performance degradation,impeding lattice oxygen diffusion to inhibit lattice oxygen participation is imperative,yet remains challenging due to the lack of efficient ***,we strategically regulate the bonding nature of Ru–O towards suppressed LOM via Ru-based high-entropy oxide(HEO)*** lattice disorder in HEOs is believed to increase migration energy barrier of lattice *** a result,the screened Ti_(23)Nb_(9)Hf_(13)W_(12)Ru_(43)O_(x) exhibits 11.7 times slower lattice oxygen diffusion rate,84%reduction in LOM ratio,and 29 times lifespan extension compared with the state-of-the-art RuO_(2) *** work opens up a feasible avenue to constructing stabilized Ru-based OER catalysts towards scalable application.

关键词： ruthenium-based high-entropy oxide suppressing the lattice oxygen diffusion acidic oxygen evolution reaction