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

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

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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

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Dynamic analysis and bifurcation control of a delayed fractional-order eco-epidemiological migratory bird model with fear effect

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International Journal of Biomathematics 2024年第3期17卷 1-33页

作者： Caihong Song ning li C ollege of Sciences Northeastern University 110819 ShenyangLiaoningP.R.China

In this paper,a new delayed fractional-order model including susceptible migratory birds,infected migratory birds and predators is proposed to discuss the spread of diseases among migratory birds.Fear of predators is considered in the model,as fear can reduce the reproduction rate and disease transmission rate among prey.First,some basic mathematical results of the proposed model are discussed.Then,time delay is regarded as a bifurcation parameter,and the delay-induced bifurcation conditions for such an uncontrolled system are established.A novel periodic pulse feedback controller is proposed to suppress the bifurcation phenomenon.It is found that the control scheme can successfully suppress the bifurcation behavior of the system,and the pulse width can be arbitrarily selected on the premise of ensuring the control effect.Compared with the traditional time-delay feedback controller,the control scheme proposed in this paper has more advantages in practical application,which not only embodies the advantages of low control cost and easy operation but also caters to the periodic changes of the environment.The proposed control scheme,in particular,remains effective even after the system has been disrupted by a constant.Numerical simulation verifies the correctness of the theoretical results.

关键词： Delayed fractional-order migratory birds fear Hopf bifurcation periodic pulse feedback

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Thermogalvanic hydrogel-based e-skin for self-powered on-body dual-modal temperature and strain sensing

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Microsystems & Nanoengineering 2024年第2期10卷 293-302页

作者： Zhaosu Wang ning li Xinru Yang Zhiyi Zhang Hulin Zhang Xiaojing Cui College of Electronic Information and Optical Engineering Taiyuan University of TechnologyTaiyuan030024China College of Materials Science and Engineering Taiyuan University of TechnologyTaiyuan030024China School of Physics and Information Engineering Shanxi Normal UniversityTaiyuan030031China

Sensing of both temperature and strain is crucial for various diagnostic and therapeutic purposes.Here,we present a novel hydrogel-based electronic skin(e-skin)capable of dual-mode sensing of temperature and strain.The thermocouple ion selected for this study is the iodine/triiodide(I−/I3−)redox couple,which is a common component in everyday disinfectants.By leveraging the thermoelectric conversion in conjunction with the inherent piezoresistive effect of a gel electrolyte,self-powered sensing is achieved by utilizing the temperature difference between the human body and the external environment.The composite hydrogels synthesized from polyvinyl alcohol(PVA)monomers using a simple freeze‒thaw method exhibit remarkable flexibility,extensibility,and adaptability to human tissue.The incorporation of zwitterions further augments the resistance of the hydrogel to dehydration and low temperatures,allowing maintenance of more than 90%of its weight after 48 h in the air.Given its robust thermal current response,the hydrogel was encapsulated and then integrated onto various areas of the human body,including the cheeks,fingers,and elbows.Furthermore,the detection of the head-down state and the monitoring of foot movements demonstrate the promising application of the hydrogel in supervising the neck posture of sedentary office workers and the activity status.The successful demonstration of self-powered on-body temperature and strain sensing opens up new possibilities for wearable intelligent electronics and robotics.

关键词： hydrogel modal utilizing

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Nano-sized stationary phase packings retained by single-particle frit for microchip liquid chromatography

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Chinese Chemical Letters 2024年第4期35卷 486-489页

作者： Wangyan Hu Ke li Xiangnan Dou ning li Xiayan Wang Center Excellence for Environmental Safety and Biological Effects Beijing Key Laboratory for Green Catalysis and SeparationDepartment of ChemistryBeijing University of TechnologyBeijing 100124China Center for Environmental Metrology National Institute of MetrologyBeijing 100029China

Modern chromatography is increasingly focused on miniaturization and integration. Compared to conventional liquid chromatography, microfluidic chip liquid chromatography(microchip-LC) has the potential due to its zero-dead volume connection and ease of integration. Nano-sized packings have the potential to significantly enhance separation performance in microchip-LC. However, their application has been hindered by packing difficulties. This study presents a method for packing nano-sized silica particles into a microchannel as the stationary phase. The microchip-LC packed column was prepared by combining the weir and the porous silica single-particle as frit to retain the packing particles. A surface tensionbased single-particle picking technique was established to insert porous single-particle frit into glass microchannels. Additionally, we developed a slurry packing method that utilizes air pressure to inject nano-sized packing into the microchannel. Pressure-driven chromatographic separation was performed using this nano-packed column integrated into a glass microchip. The mixture of four PAHs was successfully separated within just 8 min using a 5 mm separation channel length, achieving high theoretical plates(10~6plates/m). Overall, these findings demonstrate the potential of utilizing nano-sized packings for enhancing chromatographic performance in microchip systems.

关键词： Nano-size packing Single-particle frit Packed column Microchip LC Chromatographic separation

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Sustainable production of high-energy-density jet fuel via cycloaddition reactions

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Journal of Energy Chemistry 2024年第8期95卷 712-722页

作者： Yan-Cheng Hu Yingying Zhao ning li Jing-Pei Cao School of Chemical Engineering and Technology China University of Mining and Technology School of Education Science Jiangsu Normal University CAS Key Laboratory of Science and Technology on Applied Catalysis Dalian Institute of Chemical Physics Chinese Academy of Sciences

Developing an energy supply-chain based on renewable biomass holds great potential to build a low carbon society. High-energy-density(HED) jet fuel, featuring unique fused/strained cycloalkanes, is of great significance for volume-limited military aircrafts, as their high density and combustion heat can extend flight duration and increase the payload. Therefore, the exploration of biomass-based routes towards HED fuel has drawn much attention over the past decade. Cycloaddition reaction features rapid construction of various carbocycles in an atom-and step-economical fashion. This elegant strategy has been widely applied in the manufacture of sustainable HED fuel. Here we carefully summarize the progress achieved in this fascinating area and the review is categorized by the cycloaddition patterns including [4+2], [2+2],[4+4], and [2+1] cycloadditions. Besides, the energy densities of the as-prepared biofuels and petroleumbased fuels(conventional Jet-A and advanced JP-10) are also compared. This review will provide important insights into rational design of new HED fuel with different ring-types/sizes and inspire the chemists to turn those literature studies into practical applications in military field.

关键词： Biomass-based chemicals Catalysis Cycloaddition Cycloalkanes High-energy-density fuel

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Comprehensive characterization of cell disulfidptosis in human cancers:An integrated pan-cancer analysis

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Genes & Diseases 2024年第4期11卷 5-8页

作者： Guo Zhao Yale Jiang Yuning Wang Shuhang Wang ning li Clinical Trial Center National Cancer Center/National Clinical Research Center for Cancer/Cancer HospitalChinese Academy of Medical Sciences and Peking Union Medical CollegeBeijing 100021China

Excessive accumulation of disulfide molecules,like cystine,can induce disulfide stress and high toxicity in cells,but the reduced form of nicotinamide adenine dinucleotide phosphate can reverse this process and mitiga... 详细信息

关键词： disulfide cancer characterization

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Sn-decorated CeO_(2) with different morphologies for direct dehydrogenation of ethylbenzene

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Journal of Rare Earths 2024年第1期42卷 102-109,I0004页

作者： Kai Zhang Guoju Cui Mengzhen Yuan Huiwen Huang ning li Jiale Xu Guowei Wang Chunyi li State Key Laboratory of Heavy Oil Processing China University of Petroleum(East China)Qingdao266580China Petrochemical Plant of Sinopec Shengli Oilfield Company Dongying257237China College of Chemical and Biological Engineering Shandong University of Science and TechnologyQingdao266590China

Three Sn-decorated ceria catalysts with various morphologies(rods,particles,and cubes)were prepared and applied to the direct dehydrogenation of ethylbenzene.Multi-technology characterizations,including X-ray photoelectro n spectroscopy(XPS),H_(2)-tempe rature programmed reduction(H_(2)-TPR),and Raman spectroscopy,prove that the oxygen vacancies are the active sites for ethylbenzene dehydrogenation,which can be regulated by engineering CeO_(2) morphology and enhanced via introducing metal Sn.Given the results of activity test,the catalytic activities for ethylbenzene dehydrogenation over different samples are closely dependent on the amount of oxygen vacancies.The reduced Sn-decorated CeO_(2) catalyst with nanoparticles morphology exhibits better dehydrogenation performance than the other two studied catalysts at 600℃.This work provides an effective approach to regulate the active oxygen vacancies and further enhance the dehydrogenation activities through engineering the surface morphology of the catalyst and introducing suitable additives.

关键词： Ethylbenzene dehydrogenation CeO_(2) Sn Morphology Oxygen vacancy Rare earths

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Distributed Cell-Free Massive MIMO Versus Cellular Massive MIMO Under UE Hardware Impairments

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Chinese Journal of Electronics 2024年

作者： ning li Pingzhi FAN Southwest Jiaotong University

This paper first investigates and compares the uplink spectral efficiency(SE) of distributed cell-free(CF) massive multiple-input multiple-output(mMIMO) and cellular mMIMO networks, both with user equipment(UE) hardware impairments. We derive a lower bound on the uplink ergodic channel capacity of the cellular mMIMO with UE hardware impairments, based on which we determine the optimal receive combining that maximizes the instantaneous effective signal-to-interference-and-noise ratio. Then, a lower bound on the uplink capacity of a distributed CF mMIMO with UE hardware impairments is derived using the use-and-then-forget technique. On this basis, the optimum large-scale fading decoding vector is found using generalized Rayleigh entropy. By using three combining schemes of minimum mean-square error(MMSE), regularized zero-forcing(RZF), and maximum ratio, the uplink SEs of distributed CF mMIMO and cellular mMIMO networks are analyzed and compared. The results show that the two-layer decoding distributed CF mMIMO network with MMSE combining outperforms the cellular mMIMO network, and the advantage is more evident as the hardware impairment factor increases. Finally, the uplink energy efficiency(EE) of the distributed CF mMIMO networks is analyzed and evaluated through the established realistic power consumption model with hardware impairments. Simulation results show that two-layer decoding provides higher SE and EE than single-layer decoding. In addition, RZF achieves almost the same SE and EE as MMSE in a two-layer decoding architecture.

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Progress of semitransparent emerging photovoltaics for building integrated applications

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Green Energy & Environment 2024年第6期9卷 992-1015页

作者： Zhisheng Zhou Zhangyu Yuan Zhipeng Yin Qifan Xue ning li Fei Huang State Key Laboratory of Luminescent Materials and Devices School of Materials Science and EngineeringSouth China University of TechnologyGuangzhou510640China Pazhou Lab Guangzhou510320China

With the rapid development of emerging photovoltaics technology in recent years,the application of building-integrated photovoltaics(BIPVs)has attracted the research interest of photovoltaic communities.To meet the practical application requirements of BIPVs,in addition to the evaluation indicator of power conversion efficiency(PCE),other key performance indicators such as heat-insulating ability,average visible light transmittance(AVT),color properties,and integrability are equally important.The traditional Si-based photovoltaic technology is typically limited by its opaque properties for application scenarios where transparency is required.The emerging PV technologies,such as organic and perovskite photovoltaics are promising candidates for BIPV applications,owing to their advantages such as high PCE,high AVT,and tunable properties.At present,the PCE of semitransparent perovskite solar cells(ST-PSCs)has attained 14%with AVT of 22–25%;for semitransparent organic solar cells(ST-OSCs),the PCE reached 13%with AVT of almost 40%.In this review article,we summarize recent advances in material selection,optical engineering,and device architecture design for high-performance semitransparent emerging PV devices,and discuss the application of optical modeling,as well as the challenges of commercializing these semitransparent solar cells for building-integrated applications.

关键词： Building integrated photovoltaics Emerging photovoltaics Semitransparent solar cells Perovskite solar cells Organic solar cells

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