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Construction of ternary PEG200-based DESs lubrication systems via tailoring tribo-chemistry

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Friction 2024年第4期12卷 655-669页

作者： Yuting li Songyu LAN Yazhou liU cheng CAO Zicheng TANG Deyin DENG Fuyuan liU Hao li Xiaoqiang fan Minhao ZHU Key Laboratory of Advanced Technologies of Materials(Ministry of Education) School of Materials Science and EngineeringSouthwest Jiaotong UniversityChengdu 610031China Tribology Research Institute School of Mechanical EngineeringSouthwest Jiaotong UniversityChengdu 610031China

Designing novel lubricants with easily customized structures,devisable compositions,and simple and economic synthesis over traditional lubricants is critical to fulfilling complex applications,prolonging machine lifetime,and saving *** eutectic solvents(DESs),which show tunable composition,adjustable structure,easy fabrication,and environmental friendliness,are promising candidates for variable and complicated lubricants *** promote the use of DESs as lubricants,a series of PEG200-based DESs with active heteroatoms were fabricated to tailor the tribological performance via ***,PEG200/boric acid(BA)DES shows optimal lubrication performance by forming tribo-chemical reaction film composited of B2O3,iron oxides,and FeOOH,and PEG200/thiourea(TU)DES displays abrasive wear-reducing property by producing FeS tribo-chemical *** the excellent abrasive wear-resistance of PEG200/TU DES and friction reduction of PEG200/BA DES,ternary PEG200/BA/TU DESs,composited of PEG200/TU DES and PEG200/BA DES,are first *** ternary DESs possess superior wettability and thermal stability,which render them potential *** tests of the ternary DESs demonstrate that synergistic lubrication is achieved by forming a transfer film consisting of FexBy,BN,B2O3,and *** FexBy,BN,and B2O3 increase load bearing of the film,and FeS mitigates severe abrasive *** proposed design philosophy of novel DESs as lubricants opens up a unique realm that is unattainable by traditional DESs lubrication mechanisms and provides a platform to design next-generation DESs lubrication systems.

关键词： deep eutectic solvents(DESs) PEG200/boric acid DES PEG200/thiourea DES ternary DESs synergistic lubrication tribo-chemistry

Impact of non-ideal UE hardware on cell-free massive MIMO network with centralized operation

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Science China(Information Sciences) 2024年第4期67卷 255-271页

作者： Ning li Pingzhi fan Institute of Mobile Communications Southwest Jiaotong University

This paper investigates the impact of non-ideal user equipment(UE) hardware on a cell-free(CF) massive MIMO(mMIMO) network with centralized operation under spatially correlated channels. The minimum mean-squared error(MMSE) estimator can be derived with the help of the generic non-ideal UE hardware model. It is demonstrated that even if the effective signal-to-noise ratio approaches infinity, pilot contamination and imperfect hardware can cause a non-zero estimation error floor. After that, a lower bound is determined for the ergodic uplink capacity of the centralized CF mMIMO network under non-ideal UE hardware. Moreover, the optimal receive combining vector is obtained to maximize the uplink spectral efficiency(SE). The maximum ratio(MR) and regularized zero-forcing(RZF) combining schemes are offered as alternatives in light of the computational complexity of the MMSE receiver. Comparing the RZF to the MMSE scheme under different levels of hardware impairments, our findings indicate that the RZF receiver suffers a negligible loss in total SE. For MR combining, a novel closed-form uplink achievable SE expression is obtained based on the MMSE estimator and the use-and-then-forget bounding technique. This expression gives vital insights into the achievable uplink performance with UE hardware impairments. Besides, for various hardware impairment factors, the impact of pilot sequence length on average sum SE is disclosed for different receive combining schemes. To increase the overall SE of the max-min fairness scheme, a heuristic fractional power control scheme with UE hardware impairments is developed, which can essentially avoid sacrificing the SE of other UEs while maximizing the SE of the unluckiest UE in the whole network. Finally,our theoretical performance analysis and power control algorithm are validated by simulation results, and fundamental design guidelines are provided for selecting hardware satisfying the practical UE requirements.

关键词： cell-free massive MIMO centralized operation spatially correlated channels hardware impairments channel estimation uplink spectral efficiency optimal receive combining pilot length design fractional power control

Holographic superfluid ring with a weak link

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Science China(Physics,Mechanics & Astronomy) 2024年第11期67卷 29-38页

作者： Zhi-Hong li Huai-fan li Department of Physics Shanxi Datong UniversityDatong 037009China Institute of Theoretical Physics Shanxi Datong UniversityDatong 037009China

We explore the generation of topological defects in the course of a dynamical phase transition in a ring with a weak link, i.e., a SSS Josephson junction, from the AdS/CFT correspondence. By setting different parameters of the junction(width, steepness,depth) and the final temperature of the quench, the configurations of the charge density and condensate of the order parameters of the dual field theory are presented. Meanwhile, we observe that in the final equilibrium state, variations in parameters of the junctions only affect the configurations of the charge density and condensate of the order parameters, without altering their values outside the junction. However, variations in the final temperature will directly affect the values of the charge density and condensate of the order parameters outside of the junction. Moreover, in the final equilibrium state, we propose an analytic relation between the gauge-invariant velocity in the two superconducting states in the SSS Josephson junction, which agrees well with the numerical results.

关键词： AdS/CFT correspondence holographic superfluid holographic Josephson junction

Voltage-dependent P-Q Reserve Capacity Evaluation for TSO-DSO Interface Considering Uncertainties of DGs and FLs

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CSEE Journal of Power and Energy Systems 2024年第5期10卷 1935-1954页

作者： Yeyan Xu liangzhong Yao Tianjiao Pu Siyang liao fan cheng Ye li Xinying Wang School of Electrical Engineering and Automation Wuhan UniversityWuhan 430072China China Electric Power Research Institute Beijing 100085China. China Electric Power Research Institute Beijing 100192China.

Increasing distributed generators(DGs)and flexible loads(FLs)enable distribution systems to provide both active and reactive power reserves(P-Q reserves)in supporting the frequency and voltage regulations of transmission ***,such requirements at the interface between the transmission system operator(TSO)and distribution system operator(DSO)affect the distribution system operation security,considering the uncertainties of DGs and *** exploit the reserve potential of distribution systems,this paper investigates the voltagedependent P-Q reserve capacity(V-PQRC)of such types of distribution systems.V-PQRC reflects the feasible space of PQ reserves that the DSO can provide to the TSO taking the voltage deviation limit at TSO-DSO interface into consideration,while ensuring the distribution system operation security under uncertainties of DGs and *** evaluation method for VPQRC at the TSO-DSO interface is *** improve the robust performance of the evaluation method,the DG uncertainty is captured by a generalized ambiguity set and the FL uncertainty is addressed by designing a constrained sliding mode controller(CSMC).Three objectives are considered in the evaluation,i.e.,P reserve capacity,Q reserve capacity,and the voltage deviation limit at the TSO-DSO ***,a multiobjective optimization model integrating the generalized robust chance-constrained optimization and CSMC(GRCC-CSMC)is established for V-PQRC evaluation to obtain the Pareto optimal reserve ***,a non-approximated selecting(NAS)method is proposed to build up a simplified V-PQRC linear model,which can be convenient to apply in the transmissiondistribution system *** results reveal that the V-PQRC evaluation method can achieve a good performance of accuracy and robustness against uncertainties.

关键词： Generalized robust chance-constrained optimization reserve capacity evaluation sliding mode control transmission-distribution system coordination voltage-dependent P-Q reserve capacity

Progress in the preparation and physical properties of two-dimensional Cr-based chalcogenide materials and heterojunctions

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Frontiers of physics 2024年第2期19卷 105-130页

作者： Xiulian fan Ruifeng Xin li li Bo Zhang cheng li Xilong Zhou Huanzhi Chen Hongyan Zhang fangping OuYang Yu Zhou School of Physics and Electronics Hunan Key Laboratory of Nanophotonics and DevicesCentral South UniversityChangsha 410083China Jincheng Research Institute of Opto-mechatronics Industry Jincheng 048000China Shanxi Key Laboratory of Advanced Semiconductor Optoelectronic Devices and Integrated Systems Jincheng 048000China School of Physical Science and Technology Xinjiang UniversityUrumqi 830046China State Key Laboratory of Powder Metallurgy Central South UniversityChangsha 410083China

Two-dimensional transition metal dichalcogenides(TMDs)exhibit promising application prospects in the domains of electronic devices,optoelectronic devices and spintronic devices due to their distinctive energy band structures and spin−orbit coupling ***-based chalcogenides with narrow or even zero bandgap,covering from semiconductors to metallic materials,have considerable potential for wide-band photodetection and two-dimensional ***,the preparation of 2D CrX_(n)(X=S,Se,Te)nanosheets primarily relies on chemical vapor deposition(CVD)and molecule beam epitaxy(MBE),which enable the production of high-quality large-area *** review article focuses on recent progress of 2D Cr-based chalcogenides,including unique crystal structure of the CrX_(n)system,phase-controlled synthesis,and heterojunction ***,a detailed introduction of room-temperature ferromagnetism and electrical/optoelectronic properties of 2D CrXn is ***,this paper summarizes the challenges associated with utilizing 2D Cr-based chalcogenides in preparation strategies,optoelectronics devices,and spintronic devices while providing further insights.

关键词： physical properties two-dimensional materials Cr-based chalcogenide controlled synthesis heterojunction eletronic and optoelectronic devices

Role of bonding filling on HER/OER/ORR multifunctional catalytic activity in transition-metals-doped PdPX(X=S,Se,Te)

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Rare Metals 2024年第10期43卷 5126-5140页

作者： Hai-Hua Huang Wei li cheng-Chao Hu Xue-Qin Sun lin-Guo Lu Xiao-Feng fan School of Materials Science and Engineering Laboratory of Sensitive Materials and DevicesShandong Department of EducationLiaocheng University School of Environmental and Material Engineering Yantai University Department of Physics University of Puerto Rico Key Laboratory of Automobile Materials (Jilin University) Ministry of EducationCollege of Materials Science and EngineeringJilin University

The development of stable and highly efficien multifunctional electrocatalysts for the hydrogen evolution reaction （HER）,oxygen reduction reaction （ORR） and oxygen evolution reaction （OER） are essential for the efficient conversion and storage of renewable *** significant advantages of single-atom catalysts,such as strong metal slab interactions,unsaturated coordination and efficient atomic utilization,have opened new avenues for designing multifunctional ***,based on density functional theory,a single atom doped PdPX system was designed as a multifunctional electrocatalyst,which demonstrated the synergistic effect between defects and transition metal atoms and led to enhanced catalytic *** results showed that PdPS/PdPSe with P/X vacancy,PdPTe with P/Pd vacancy and Co/Rh/Ir@PdPX exhibited promising HER ***@PdPS（Se）,with an overpotential of 0.56（0.44） V,was predicted to be a promising OER ***,Rh（Ir）@PdPS（Se）catalysts exhibited efficient catalytic properties for ORR Besides,Co@PdPS（Se）,Rh（Ir）@PdPSV（S）,Co@PdP-SeV（Se）and Ir@PdPSV（S）-1exihibited multifunctional catalytic performance with moderate ***,the origin of catalytic activity was revealed by using the crystal orbital Hamilton populations *** a strong adsorption system,proper filling of the anti-bonding state can increase the energy of the system,weaken the adsorption strength,and facilitate the desorption of intermediates Conversely,augmenting bonding states can enhance its adsorption *** findings provide theoretica guidance for the design and fabrication of novel multifunctional electrocatalysts in terms of filling of bondingstate.

关键词： Density functional theory Electrocatalyst Two-dimensional PdPX Water splitting

Magnesium doping to improve the light to heat conversion of OMS-2 for formaldehyde oxidation under visible light irradiation

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Chinese Chemical Letters 2024年第4期35卷 193-198页

作者： Tingting liu Pengfei Sun Wei Zhao Yingshuang li Lujun cheng Jiahai fan Xiaohui Bi Xiaoping Dong College of Chemistry and Chemical Engineering Zhejiang Sci-Tech UniversityHangzhou 310018China College of Environmental Science and Engineering Nankai UniversityTianjin 300071China Hangzhou Kaiming Catalyst Co. Ltd.Hangzhou 310013China

Mg-doped manganese oxide octahedral molecular sieve(Mg-OMS-2)catalysts were prepared by hydrothermal *** photothermal degradation performance of these catalysts for formaldehyde(HCHO)in batch system and continuous system was *** light absorption of OMS-2 was increased by Mg-doped,especially for near infrared light,which promoted surface temperature reach a maximum of 214.8℃ under xenon *** this temperature,the reinforced surface lattice oxygen and oxygen vacancy that formed by lattice distortion via Mg-doped were *** best HCHO elimination efficiency was achieved over Mg_(0.2)/OMS-2 catalyst with Mg^(2+)/Mn^(2+)=1/5,which could reduce HCHO from 250 ppm to 10 ppm within 20 *** in situ DRIFTS was also carried out to monitor the changes in the content of reaction intermediates and analyze the degradation paths of *** was found the HCHO was attacked by formed·OH and·O^(2-) to generate formate species and carbonate species,and finally transformed to CO_(2) and H_(2)*** photothermal catalytic oxidation process exhibited a high efficiency purification of HCHO without the help of extra energy consumption.

关键词： Mg doping Photothermal catalysis OMS-2 HCHO Reaction mechanism

Mixing states and secondary formation processes of organic nitrogen-containing single particles in Guangzhou,China

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Journal of Environmental Sciences 2024年第4期138卷 62-73页

作者： lijun Yun Chunlei cheng Suxia Yang Zaihua Wang Mei li Qi En Zhong liyuanMao Sulin liu Xiaoya cheng Duanying Chen fan Yang Zhen Zhou Institute of Mass Spectrometry and Atmospheric Environment Guangdong Provincial Engineering Research Center for on-line source apportionment system of air pollutionJinan UniversityGuangzhou 510632China Guangdong-Hongkong-Macao Joint Laboratory of Collaborative Innovation for Environmental Quality Guangzhou 510632China State Key Laboratory of Loess and Quaternary Geology Institute of Earth EnvironmentChinese Academy ScienceXi’an 710061China Institute for Environment and Climate Research Jinan UniversityGuangzhou 510632China Guangdong Academy of Sciences Institute of Resources Utilization and Rare Earth DevelopmentGuangzhou 510650China Environmental Monitoring Station of Pudong New District Shanghai 201200China

Organic nitrogen(ON)compounds play a significant role in the light absorption of brown carbon and the formation of organic aerosols,however,the mixing state,secondary formation processes,and influencing factors of ON compounds are still *** paper reports on the mixing state of ON-containing particles based on measurements obtained using a highperformance single particle aerosol mass spectrometer in January 2020 in *** ON-containing particles accounted for 21% of the total detected single particles,and the particle count and number fraction of the ON-containing particles were two times higher at night than during the *** prominent increase in the content of ON-containing particles with the enhancement of NO_xmainly occurred at night,and accompanied by high relative humidity and nitrate,which were associated with heterogeneous reactions between organics and gaseous NO_(x)and/or NO_(3)*** synchronous decreases in ON-containing particles and the mass absorption coefficient of water-soluble extracts at 365 nm in the afternoon may be associated with photo-bleaching of the ON species in the *** addition,the positive matrix factorization analysis found five factors dominated the formation processes of ON particles,and the nitrate factor(33%)mainly contributed to the production of ON particles at *** results of this study provide unique insights into the mixing states and secondary formation processes of the ON-containing particles.

关键词： Organic nitrogen compounds Single particles Mixing state Secondary formation Nighttime chemistry

Room-temperature Self-healing and Recyclable PDMS Elastomers with Superior Mechanical Properties for Triboelectric Nanogenerators

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Chinese Journal of Polymer Science 2024年第10期42卷 1566-1577,I0014页

作者： Shu-Juan Wang Lu Wang Hong-Zhe Su Zhi-cheng Wu Qiao-Gen Zhang Wei fan Xin-li Jing School of Chemistry Joint Innovation Center of Thermal Protection MaterialsXi’an Jiaotong UniversityXi’an710049China School of Electrical Engineering Xi’an Jiaotong UniversityXi’an710049China School of Textile Science and Engineering Xi’an Polytechnic UniversityXi’an710048China

Polydimethylsiloxane(PDMS)is an electron-withdrawing material that is widely used in triboelectric nanogenerators(TENGs).However,PDMS has poor mechanical properties after curing and is easily damaged when subjected to long-term ***,the long-term stable operation of TENGs under mechanical deformation cannot be *** this work,multiple hydrogen bonds and aromatic disulfide bonds were introduced into PDMS *** elastomers exhibited high toughness(a tensile strength of 1.91 MPa and an elongation at break of 340%),good recyclability,and room-temperature self-healing properties(healing efficiency of 96.4%in 24 h).Recyclable sandwich-like triboelectric nanogenerators with excellent electrical output performance(13.5 V)and room-temperature self-healing performance(24 h,98%recovery of self-generating performance)were prepared by utilizing the hydrogen bonding between the PDMS elastomer and *** work reported herein offers theoretical guidance and a compelling strategy for developing high-performance TENG negative friction layers.

关键词： Polydimethylsiloxane Aromatic disulfide bonds Hydrogen bonds Room temperature self-healing Triboelectric nanogenerator