检索结果-南通市图书馆

Coherent optical frequency transfer via 972-km fiber link

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2024年第2期33卷 277-282页

作者：邓雪张翔臧琦焦东东王丹刘杰高静许冠军董瑞芳刘涛张首刚 National time Service Centre Chinese Academy of SciencesXi’an 710600China Key Laboratory of time Reference and Application Chinese Academy of SciencesXi’an 710600China School of Communications and Information Engineering and School of Artificial Intelligence Xi’an University of Posts and TelecommunicationsXi’an 710121Chin

We demonstrate coherent optical frequency dissemination over a distance of 972 km by cascading two spans where the phase noise is passively compensated *** of employing a phase discriminator and a phase locking loop in the conventional active phase control scheme,the passive phase noise cancellation is realized by feeding double-trip beat-note frequency to the driver of the acoustic optical modulator at the local *** passive scheme exhibits fine robustness and reliability,making it suitable for long-distance and noisy fiber *** optical regeneration station is used in the link for signal amplification and cascaded *** phase noise cancellation and transfer instability of the 972-km link is investigated,and transfer instability of 1.1×10^(-19)at 10^(4)s is *** work provides a promising method for realizing optical frequency distribution over thousands of kilometers by using fiber links.

关键词： optical frequency transfer fiber link phase noise cancellation

Scalable orthogonal delay-division multiplexed OEO artificial neural network trained for TI-ADC equalization

在线全文

学校读者我要写书评

暂无评论

Photonics Research 2024年第1期12卷 85-105页

作者： ANDREA ZAZZI ARKA DIPTA DAS LUKAS HüSSEN RENATO NEGRA JEREMY WITZENS Institute of Integrated Photonics RWTH Aachen University52074 AachenGermany Chair of High-frequency Electronics RWTH Aachen University52074 AachenGermany

We propose a new signaling scheme for on-chip optical-electrical-optical artificial neural networks that utilizes orthogonal delay-division multiplexing and pilot-tone-based self-homodyne *** scheme offers a more efficient scaling of the optical power budget with increasing network *** simulations,based on220 nm silicon-on-insulator silicon photonics technology,suggest that the network can support 31×31 neurons,with 961 links and freely programmable weights,using a single 500 m W optical comb and a signal-to-noise ratio of 21.3 d B per ***,it features a low sensitivity to temperature fluctuations,ensuring that it can be operated outside of a laboratory *** demonstrate the network’s effectiveness in nonlinear equalization tasks by training it to equalize a time-interleaved analog-to-digital converter(ADC)architecture,achieving an effective number of bits over 4 over the entire 75 GHz ADC *** anticipate that this network architecture will enable broadband and low latency nonlinear signal processing in practical settings such as ultra-broadband data converters and real-time control systems.

关键词： network delay artificial

Recent research in mechanical properties of geopolymer-based ultrahigh-performance concrete:A review

在线全文

学校读者我要写书评

暂无评论

Defence Technology（防务技术） 2024年第2期32卷 67-88页

作者： G.Murali division of Research&Innovation Uttaranchal UniversityDehradun 248007India

Due to the growing need for sustainable and ultra-high-strength construction materials,scientists have created an innovative ultra-high-performance concrete called Geopolymer based ultra-highperformance concrete(GUHPC).Besides,in the last few decades,there have been a lot of explosions and ballistic attacks around the world,which have killed many civilians and fighters in border *** this context,this article reviews the fresh state and mechanical properties of ***,the ingredients of GUHPC and fresh properties such as setting time and flowability are briefly ***,the review of compressive strength,flexure strength,tensile strength and modulus of elasticity of fibrous ***,the blast and projectile impact resistance performance was ***,the microstructural characteristics were reviewed using the scanning electron microscope and X-ray Powder *** review outcome reveals that the mechanical properties were increased when 30%silica fume was added to a higher dose of steel fibre to improve the microstructure of *** is hypothesized that the brittleness of GUHPC was mitigated by adding 1.5%steel fibre reinforcement,which played a role in the decrease of contact explosion cratering and *** the need for cement in GUHPC was a key factor in the review,indicating a promising potential for lowering carbon ***,GUHPC research is still in its early stages,so more study is required before its full potential can be utilized.

关键词： Mechanical properties Blast Projectile impact Fibre Geopolymer Silica fume Alkaline activators

A Novel Prescribed-Performance Path-Following Problem for Non-Holonomic Vehicles

在线全文

学校读者我要写书评

暂无评论

IEEE/CAA Journal of Automatica Sinica 2024年第6期11卷 1476-1484页

作者： Zirui Chen Jingchuan Tang Zongyu Zuo Seventh Research division Beihang University(BUAA)Beijing 100191China IEEE

The issue of achieving prescribed-performance path following in robotics is addressed in this paper,where the aim is to ensure that a desired path within a specified region is accu-rately converged to by the controlled *** this context,a novel form of the prescribed performance guiding vector field is introduced,accompanied by a prescribed-time sliding mode con-trol ***,the interdependence among the pre-scribed parameters is *** validate the effectiveness of the proposed method,numerical simulations are presented to demonstrate the efficacy of the approach.

关键词： Guiding vector field non-holonomic vehicle path following prescribed performance sliding mode control

Solid-state impedance spectroscopy studies of dielectric properties and relaxation processes in Na_(2)O–V_(2)O_(5)–Nb_(2)O_(5)–P_(2)O_(5) glass

在线全文

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 2024年第1期31卷 186-196页

作者： Sara Marijan Luka Pavic division of Materials Chemistry Ruđer Boskovic InstituteBijenicka 54HR-10000 ZagrebCroatia

Solid-state impedance spectroscopy(SS-IS)was used to investigate the influence of structural modifications resulting from the addition of Nb2O5 on the dielectric properties and relaxation processes in the quaternary mixed glass former(MGF)system 35Na_(2)O–10V_(2)O_(5)–(55-x)P_(2)O_(5)–xNb_(2)O_(5)(x=0–40,mol%).The dielectric parameters,including the dielectric strength and dielectric loss,are determined from the frequency and temperature-dependent complex permittivity data,revealing a significant dependence on the Nb2O5 *** transition from a predominantly phosphate glass network(xfrequency dependence of imaginary part of electrical modulus,M″(ω),Nb-40 glass-ceramic exhibits two distinct contributions with similar relaxation *** high-frequency peak indicates bulk ionic conductivity,while the additional low-fre-quency peak is associated with the grain boundary effect,confirmed by the electrical equivalent circuit(EEC)*** scaling characteristics of permittivity and conductivity spectra,along with the electrical modulus,validate time-temperature superposition and demonstrate a

关键词： phosphate glasses glass-ceramics impedance spectroscopy dielectric properties relaxation processes permittivity scaling conductivity scaling modulus formalism

Red cell distribution width/platelet ratio estimates the 3-year risk of decompensation in Metabolic Dysfunction-Associated Steatotic Liver Disease-induced cirrhosis

在线全文

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2024年第7期30卷 685-704页

作者： Marcello Dallio Mario Romeo Paolo Vaia Salvatore Auletta Simone Mammone Marina Cipullo Luigi Sapio Angela Ragone Marco Niosi Silvio Naviglio Alessandro Federico Department of Precision Medicine Hepatogastroenterology DivisionUniversity of Campania Luigi VanvitelliNaples 80138Italy Department of Precision Medicine Clinical Biochemistry DivisionUniversity of Campania Luigi VanvitelliNaples 80138Italy

BACKGROUND For compensated advanced chronic liver disease(cACLD)patients,the first decompensation represents a dramatically worsening prognostic *** on the first decompensation event(DE),the transition to decompensated advanced chronic liver disease(dACLD)can occur through two modalities referred to as acute decompensation(AD)and non-AD(NAD),*** Significant Portal Hypertension(CSPH)is considered the strongest predictor of decompensation in these ***,due to its invasiveness and costs,CSPH is almost never evaluated in clinical ***,recognizing noninvasively predicting tools still have more appeal across healthcare *** red cell distribution width to platelet ratio(RPR)has been reported to be an indicator of hepatic fibrosis in Metabolic Dysfunction-Associated Steatotic Liver Disease(MASLD).However,its predictive role for the decompensation has never been *** In this observational study,we investigated the clinical usage of RPR in predicting DEs in MASLD-related cACLD *** Fourty controls and 150 MASLD-cACLD patients were consecutively enrolled and followed up(FUP)semiannually for 3 *** baseline,biochemical,clinical,and Liver Stiffness Measurement(LSM),Child-Pugh(CP),Model for End-Stage Liver Disease(MELD),aspartate aminotransferase/platelet count ratio index(APRI),Fibrosis-4(FIB-4),Albumin-Bilirubin(ALBI),ALBI-FIB-4,and RPR were *** FUP,DEs(timing and modaities)were *** was assessed at the baseline and on DE occurrence according to the available Clinical Practice *** Of 150 MASLD-related cACLD patients,43(28.6%)progressed to dACLD at a median time of 28.9 months(29 NAD and 14 AD).Baseline RPR values were significantly higher in cACLD in comparison to controls,as well as MELD,CP,APRI,FIB-4,ALBI,ALBI-FIB-4,and LSM in dACLD-progressing compared to cACLD individuals[all P<0.0001,except for FIB-4(P:0.007)and ALBI(P:0.011)].Receiving operator curve a

关键词： Liver cirrhosis Red blood cell distribution width Red blood cell distribution width to platelet ratio Translational Medicine Prognostic biomarker

Interrogation of optical Ramsey spectrum and stability study of an ^(87)Sr optical lattice clock

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Physics B 2022年第3期31卷 306-310页

作者：夏京京卢晓同常宏 CAS Key Laboratory of time and frequency Primary Standards National Time Service CenterXi'an 710600China University of Chinese Academy of Sciences(CAS) Beijing 100049China

The optical Ramsey spectrum is experimentally realized in an ^(87)Sr optical lattice clock, and the measured linewidth agrees well with theoretical expectation. The coherence time between the clock laser and the atoms, which indicates the maximum free evolution period of using Ramsey detection to measure the atom-laser phase information, is determined as 340(23) ms by measuring the fringe contrasts of the Ramsey spectrum as a function of the free evolution period. Furthermore, with the same clock duty cycle of about 0.1, the clock stability is measured by using the Ramsey and Rabi spectra,respectively. The experimental and theoretical results show approximately the same stability as the two detection methods, which indicates that Ramsey detection cannot obviously improve the clock stability until the clock duty cycle is large enough. Thus, it is of great significance to choose the detection method of a specific clock.

关键词： optical Ramsey spectrum optical lattice clock stability coherence time

All-fiber telecom band energy-time entangled biphoton source

在线全文

学校读者我要写书评

暂无评论

Chinese Optics Letters 2023年第3期21卷 127-131页

作者：刘妤婷邢俊杰夏志广权润爱洪辉博刘涛张首刚项晓董瑞芳 Key Laboratory of time and frequency Primary Standards National Time Service CenterChinese Academy of Sciences School of Astronomy and Space Science University of Chinese Academy of SciencesBeijing 100049China

We report an all-fiber telecom-band energy-time entangled biphoton source with all physical elements integrated into a compact *** a pump power of 800μW,the photon pairs generation rate reaches 6.9 MHz with the coincidence-toaccidental ratio[CAR]better than *** long-term stability of the biphoton source is characterized by measuring the Hong-Ou-Mandel interference visibility and CAR within a continuous operation period of more than 10 *** from the advantages of compact size,light weight,and high stability,this device provides a convenient resource for various field turnkey quantum communication and metrology applications.

关键词： energy±time entanglement all-fiber biphoton source Hong±Ou±Mandel interference

Finite-time Stabilization for Constrained Discrete-time Systems by Using Model Predictive Control

在线全文

学校读者我要写书评

暂无评论

IEEE/CAA Journal of Automatica Sinica 2024年第7期11卷 1656-1666页

作者： Bing Zhu Xiaozhuoer Yuan Li Dai Zhiwen Qiang IEEE the Seventh Research division Beihang UniversityBeijing 100191China the School of Automation Beijing Institute of TechnologyBeijing 100081China

In this paper, a model predictive control(MPC)framework is proposed for finite-time stabilization of linear and nonlinear discrete-time systems subject to state and control constraints. The proposed MPC framework guarantees the finite-time convergence property by assigning the control horizon equal to the dimension of the overall system, and only penalizing the terminal cost in the optimization, where the stage costs are not penalized explicitly. A terminal inequality constraint is added to guarantee the feasibility and stability of the closed-loop *** feasibility can be improved via augmentation. The finite-time convergence of the proposed MPC is proved theoretically,and is supported by simulation examples.

关键词： Constraints deadbeat control finite-time stabilization model predictive control(MPC)