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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

Imprints of ultralight axions on the gravitational wave and pulsar timing measurement

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Science China(Physics,Mechanics & Astronomy) 2024年第1期67卷 23-29页

作者： ning Xie Fa Peng Huang MOE Key Laboratory of TianQin Mission TianQin Research Center for Gravitational Physics&School of Physics and AstronomyFrontiers Science Center for TianQinGravitational Wave Research Center of CNSASun Yat-sen University(Zhuhai Campus)Zhuhai 519082China

The axion or axion-like particle motivated from a natural solution of strong CP problem or string theory is a promising dark matter candidate.We study the new observational effects of ultralight axion-like particles by the space-borne gravitational wave detector and the radio telescope.Taking the neutron star-black hole binary as an example,we demonstrate that the gravitational waveform could be obviously modified by the slow depletion of the axion cloud around the black hole formed through the superradiance process.We compare these new effects on the binary with the well-studied effects from dynamical friction with dark matter and dipole radiation in model-independent ways.Finally,we discuss the constraints from LIGO/Virgo and study the detectability of the ultralight axion particles at LISA and TianQin.

关键词： gravitational wave axion dark matter

Phosphine-Catalyzed [4+3] Annulation Reaction of Indole Derivatives with MBH Carbonates:A Facile Access to Indole-1,2-fused 1,4-Diazepinones and Azepines

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Chinese Journal of Chemistry 2024年第3期42卷 271-275页

作者： Yannan Zhu Haoran Jiang Yi-ning Wang Faculty of Chemistry and Chemical Engineering Yancheng Institute of TechnologyYanchengJiangsu224051 China

A phosphine-catalyzed [4+3] annulation between dinucleophilic indole derivatives and Morita−Baylis−Hillman (MBH) carbonates was discovered by using the N1 and N4′/C4′ nucleophilicities of the indole precursors,in which indoles act as four atom synthons. This protocol provides an efficient and facile access to indole-1,2-fused 1,4-diazepinones and azepines in good to high yields in one step,which illustrates potential synthetic utilities in drug discovery.

关键词： Phosphine catalysis [4+3]Annulation Indole derivatives Nitrogen heterocycles Organocatalysis

Performance enhancement of perovskite solar cells:surface is the key

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Science China Materials 2024年第1期67卷 375-376页

作者： Wenzhuo Li Zhijun ning School of Physical Science and Technology Shanghaitech UniversityShanghai 201210China

Metal halide perovskite solar cells(PSCs)stand out as one of the most promising contenders among photovoltaic technologies for the future.Over the past decade,PSCs with high power conversion efficiency(PCE)predominantly adopted the normal(ni-p)device structure.However,a common p-type organic small molecule,Spiro-OMe TAD,which is widely employed at the top layer of n-i-p devices[1],faces issues such as susceptibility to water absorption and poor thermal stability.

关键词： structure stability perovskite

Even-odd layer-dependent multiferroic in freestanding rare-earth orthorhombic perovskite

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Science China(Physics,Mechanics & Astronomy) 2024年第7期67卷 151-157页

作者： Shaowen Xu Fanhao Jia ning Dai School of Physics and Optoelectronic Engineering Hangzhou Institute for Advanced StudyUniversity of Chinese Academy of SciencesHangzhou 310024China Department of Physics College of ScienceHangzhou Dianzi UniversityHangzhou 310018China State Key Laboratory of Infrared Physics Shanghai Institute of Technical PhysicsChinese Academy of SciencesShanghai 200083China

Freestanding oxide perovskites possess strong interlayer coupling between adjacent atomic layers,thus exerting a determinative effect on the magnetism and ferroelectricity of these atomic-scale materials.Here,we propose an effective strategy to manipulate magnetism and ferroelectricity in freestanding rare-earth orthorhombic perovskite via modulation of layer thickness.By performing first-principles calculations,an even-odd oscillation is demonstrated in few-layer GdAlO_(3)perovskite(GAP).Specifically,odd-layer systems with charged atomic layers are ferromagnetic polar metals,while even-layer systems are antiferromagnetic ferroelectric semiconductors.This thickness-dependent magnetic phase transition originates from carrier doping,as rationalized by the Stoner criterion.Furthermore,we demonstrate the promotion of in-plane ferroelectricity via the concurrent application of two distinct antiferrodistortive displacements,each driven by formation and breaking of bonds.Analogous multiferroic phases may emerge in other transition metal oxide perovskites supporting multiple valence states,e.g.,few-layer Gd MO_(3)(M=V,Cr,Mn,and Ni).This work puts forward a strategy for layer thickness engineering of magnetism and ferroelectricity in 2D oxide perovskite multiferroic materials.

关键词： few-layer rare-earth perovskite multiferroicity size effect first principles calculations

Deployment analysis of composite thin-walled lenticular tubes with effect of storage time and temperature

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Chinese Journal of Aeronautics 2024年第1期37卷 162-172页

作者： Jinfeng DENG ning AN Qilong JIA Xiaofei MA School of Aeronautics and Astronautics Sichuan UniversityChengdu 610065China State Key Laboratory for Strength and Vibration of Mechanical Structures School of AerospaceXi’an Jiaotong UniversityXi’an 710049China State Key Laboratory of Structural Analysis for Industrial Equipment Dalian University of TechnologyDalian 116024China Xi’an Institute of Space Radio Technology Xi’an 710100China

Composite Thin-walled Lenticular Tube(CTLT)is increasingly utilized in small satellites missions as a lightweight,foldable,and rollable structural material that facilitates the construction of large deployable systems.The CTLT is initially flattened and coiled around a central hub for storage before launch,during which elastic energy is stored as deformation energy,allowing it to be self-deployed on demand for use in orbit.This work presents a comprehensive investigation into the coiling,storage and deployment behaviors of CTLT that wraps around a central hub.A nonlinear explicit dynamic finite element model was developed with both deformable CTLT and rigidbodies mechanisms including the central hub and guide rollers,as well as the complex interactions among them.The coiling mechanics characteristics such as stored strain energy and rotational moment were presented and validated against experimental data in the literature.Then,the dynamic deployment behaviors were analyzed in terms of two different deployment methods,namely,controlled deployment and free deployment.The effect of material property change during storage was also discussed through numerical experiments.

关键词： Composite deployable structures Deployment dynamics Finite element method Stress relaxation Thin-walled booms

Exploration of cardiac rehabilitation nursing for elderly patients with myocardial infarction based on individualized cardiac rehabilitation

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World Journal of Clinical Cases 2024年第2期12卷 256-266页

作者： Hua-ning Liu Bo Gao Department of Geriatrics General Hospital of the YangTze River ShippingWuhan Brain HospitalWuhan 430015Hubei ProvinceChina Department of Cardiology Suizhou Central HospitalAffiliated Hospital of Hubei University of MedicineSuizhou 441300Hubei ProvinceChina

BACKGROUND Myocardial infarction is a high-risk condition prevalent among the elderly population,often leading to adverse clinical manifestations such as reduced cardiopulmonary function,anxiety,and depression post-surgery.Consequently,cardiac rehabilitation holds immense importance in mitigating these complications.AIM To evaluate the effect of individualized cardiac rehabilitation on blood pressure variability(BPV)and baroreflex sensitivity(BRS)in elderly patients with myocardial infarction.METHODS A cohort of 74 elderly patients diagnosed with myocardial infarction and admitted to our hospital between January 2021 and January 2022 were subjected to random selection.Subsequently,all patients were divided into two groups,namely the research group(n=37)and the control group(n=37),utilizing the number table method.The control group received conventional drug treatment and nursing guidance intervention,while the study group underwent individualized cardiac rehabilitation in addition to the interventions received by the control group.All patients were continuously intervened for 12 wk,and the BPV of these two groups in the 1st wk(T0),the 4th wk(T1)and the 12th wk(T2)were compared,BRS,changes in cardiopulmonary function measures,and adverse cardiovascular events.RESULTS Of 24 h diastolic BPV,24 h systolic BPV,carbon dioxide ventilation equivalent slope of the research group were lower than those of the control group at T1 and T2,BRS,peak heart rate and systolic blood pressure product,1 min heart rate recovery were higher than those of the control group,and the incidence of adverse events in the research group was lower than that of the control group,the difference was statistically significant(P<0.05).CONCLUSION In this study,we found that after individualized cardiac rehabilitation in elderly patients with myocardial infarction,BPV and BRS can be effectively improved,cardiac function is significantly enhanced,and a better prognosis is obtained.

关键词： Individualized cardiac rehabilitation Myocardial infarction Variability in blood pressure Baroreflex sensitivity

Practical effect of different teaching modes in teaching gastrointestinal surgery nursing

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World Journal of Gastrointestinal Surgery 2024年第1期16卷 166-172页

作者： Xiao-Juan Rong Zhen ning Department of Nursing Medical College in Jiangxi University of TechnologyNanchang 330098Jiangxi ProvinceChina

BACKGROUND With the continuous development and progress of medical technology,the position of surgical nursing in the field of clinical medicine is becoming in-creasingly prominent.As an important branch of the surgical field,the nursing requirements and difficulty of gastrointestinal surgery are also increasing.In order to improve the teaching quality of nursing care in gastrointestinal surgery,many educators and researchers are actively exploring new teaching methods.Among them,the teaching method case-based learning(CBL),scene-simulated learning(SSL),task-based learning(TBL),combining self-evaluation and training mode is considered as an effective method.This method aims to help students to better master knowledge and skills and improve their comprehensive quality by cultivating their self-evaluation ability.AIM To explore the practical effect of CBL-SSL-TBL combined with training mode and student self-assessment in nursing teaching of gastrointestinal surgery.METHODS Seventy-one nursing interns in our hospital from December 2020 to December 2021 were selected.According to different teaching modes,they were divided into observation group CBL-SSL-TBL combined with training mode combined with student self-assessment and control group(conventional teaching mode),of which 36 were in observation group and 35 were in control group.The results of operational skills,theoretical knowledge,nursing students'satisfaction,learning effectiveness questionnaire and teaching effect were compared between the two groups.RESULTS Compared between the two groups,the operational skills and theoretical knowledge scores of the observation group were higher than those of the control group,and the difference was statistically significant(P<0.05).Compared between the two groups,the total satisfaction ratio of the observation group was higher than that of the control group,the difference was statistically significant(P<0.05).Compared between the two groups,the observation group was lower than the control group in the questionnaire results

关键词： Gastrointestinal surgery Nursing teaching Teaching model Practical effect Learning ability

Fullerenes and derivatives as electrocatalysts: Promises and challenges

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Green Energy & Environment 2024年第1期9卷 7-27页

作者： Kun Guo ning Li Lipiao Bao Xing Lu State Key Laboratory of Materials Processing and Die&Mould Technology School of Materials Science and EngineeringHuazhong University of Science and TechnologyWuhan430074China

Carbon-based metal-free nanomaterials are promising alternatives to precious metals as electrocatalysts of key energy storage and conversion technologies.Of paramount signiﬁcance are the establishment of design principles by understanding the catalytic mechanisms and identifying the active sites.Distinct from sp2-conjugated graphene and carbon nanotube,fullerene possesses unique characteristics that are growingly being discovered and exploited by the electrocatalysis community.For instance,the well-deﬁned atomic and molecular structures,the good electron afﬁnity to tune the electronic structures of other substances,the intermolecular self-assembly into superlattices,and the on-demand chemical modiﬁcation have endowed fullerene with incomparable advantages as electrocatalysts that are otherwise not applicable to other carbon ma-terials.As increasing studies are being reported on this intriguing topic,it is necessary to provide a state-of-the-art overview of the recent progress.This review takes such an initiative by summarizing the promises and challenges in the electrocatalytic applications of fullerene and its derivatives.The content is structured according to the composition and structure of fullerene,including intact fullerene(e.g.,fullerene composite and superlattices)and fullerene derivatives(e.g.,doped,endohedral,and disintegrated fullerene).The synthesis,characterization,catalytic mechanisms,and deﬁciencies of these fullerene-based materials are explicitly elaborated.We conclude it by sharing our perspectives on the key aspects that future efforts shall consider.

关键词： Fullerene Fullerene derivative Metal-free catalyst Structural defect Electrocatalyst