检索结果-南通市图书馆

Journal of Rare Earths 2024年第8期42卷 1470-1478页

作者： Payal Khajuria M.Manhas A.K.Bedyal Ankush Vij H.C.Swart Vinay Kumar department of Physics and Astronomical Sciences Central University of Jammu department of Physics School of SciencesCluster University of Jammu department of Physics University of Petroleum and Energy Studies department of Physics University of the Free State

Highly pure red phosphors LiM（PO3）3:Eu3+（M=Sr,Ca） doped with Eu3+（1 mol%） were synthesized via solution combustion method and their crystal structure and luminescence dynamics were studied to explore its suitability in white light emitting *** Rietveld refinement analysis of the powder Xray diffraction patterns reveals that the phosphors belong to the pure triclinic phase of LiSr（PO3）3and LiCa（PO3） with space group P-■（2）.The scanning electron microscopy images showed the agglomerated *** photoluminescence emission spectra under 393 nm show an orange band at 594 nm and a red band at 613 nm ascribed to5D0→7F1.5D0→7F2transitions of Eu3+ion in both the ***,the spectroscopic properties such as luminescence behaviour,and Stark splitting were used to examine the symmetry of Eu3+ions in LiM（PO3）3:Es3+（M=Sr,Ca） phosphors in terms of distortion induced upon *** Stark splitting shows that the actual site symmetry for Eu3+ion was estimated to be D2type for both *** photometric properties of LiCa（PO3）3:Eu3+such as Commission International de l'Eclairage coordinates（x=0.64,y=0.36） near to the standard one（red）,high color purity（95%） and higher brightness reveal that the phosphor has the capability of acting as a red component in n-UV white light emitting diodes.

关键词： Phosphate Photoluminescence Rare earths Stark splitting WLEDs

Injection of a Self-propelled Polymer into a Small Circular Cavity

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2024年第6期42卷 886-894页

作者： Chao Wang Yan-Li Zhou Xiao Yang Fan Wu Meng-Bo Luo department of Physics Taizhou UniversityTaizhou318000China department of Physics Zhejiang UniversityHangzhou310027China

The injection of a polymer chain into a small circular cavity under tangential self-propelled force is studied by using Langevin dynamics *** indicate that the injection dynamics of the active polymer shows strong correlation with the polymer conformation inside the cavity depending on the polymer rigidity(k_(b)).The injection timeτvaries nonmonotonously with increasing k_(b),and reaches its minimum at k_(b)^(*).When k_(b) is small(k_(b)≪k_(b)^(*)),the polymer is nearly random coil in the cavity,and spends a long time at the final stage of the injection process due to the large repulsion between monomers inside the *** k_(b) is moderate(k_(b)∼k_(b)^(*)),the part of polymer inside the cavity forms spiral configuration under the tangential active force,and the whole polymer moves synchronously with a constant velocity during the injection process,leading to a small injection *** k_(b) is large(k_(b)≫k_(b)^(*)),the polymer is nearly straight at the initial stage of the injection process,and takes a long time to bend itself,leading to a large injection time.

关键词： Active Polymer Injection Dynamics Simulation

维普期刊数据库

A Matching Algorithm with Reinforcement Learning and Decoupling Strategy for Order Dispatching in On-Demand Food Delivery

在线全文

学校读者我要写书评

暂无评论

Tsinghua Science and Technology 2024年第2期29卷 386-399页

作者： Jingfang Chen Ling Wang Zixiao Pan Yuting Wu Jie Zheng Xuetao Ding department of Automation Tsinghua UniversityBeijing 100084China department of Delivery Technology MeituanBeijing 100102China

The on-demand food delivery(OFD)service has gained rapid development in the past decades but meanwhile encounters challenges for further improving operation *** order dispatching problem is one of the most concerning issues for the OFD platforms,which refer to dynamically dispatching a large number of orders to riders reasonably in very limited decision *** solve such a challenging combinatorial optimization problem,an effective matching algorithm is proposed by fusing the reinforcement learning technique and the optimization ***,to deal with the large-scale complexity,a decoupling method is designed by reducing the matching space between new orders and ***,to overcome the high dynamism and satisfy the stringent requirements on decision time,a reinforcement learning based dispatching heuristic is *** be specific,a sequence-to-sequence neural network is constructed based on the problem characteristic to generate an order priority ***,a training approach is specially designed to improve learning ***,a greedy heuristic is employed to effectively dispatch new orders according to the order priority *** real-world datasets,numerical experiments are conducted to validate the effectiveness of the proposed *** results show that the proposed algorithm can effectively solve the problem by improving delivery efficiency and maintaining customer satisfaction.

关键词： order dispatching on-demand delivery reinforcement learning decoupling strategy sequence-to-sequence neural network

Influence of aging, mitochondrial dysfunction, and inflammation on Parkinson's disease

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

Neural Regeneration Research 2024年第6期19卷 1197-1198页

作者： Davide Cossu Nobutaka Hatiori department of Neurology Juntendo University department of Biomedical Sciences Sassari University

Aging is associated with chronic form of inflammation called inflammaging,which results from immune system *** plays a crucial role in the pathogenesis of various neurodegenerative diseases(Dabravolski et al.,2022).Mo...

关键词：

Statistical analysis and interpretation on lightning impulse breakdown voltages of ester liquids under varying field uniformity

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

High Voltage 2024年第1期9卷 22-34页

作者： Haichuan Yu Qiang Liu Zhongdong Wang department of Electrical and Electronic Engineering The University of ManchesterManchesterUK department of Engineering University of ExeterExeterUK

Ester liquids(ELs),as the alternative transformer liquids to the conventional mineral oils(MOs),have been increasingly used in power transformers with high voltage *** various properties,the lightning impulse breakdown voltages(LIBDVs)have been studied elaborately in the past two decades under different electric field *** electric field uniformities do have an effect on the breakdown characteristics,for example,breakdown mechanisms,polarity effects,and differences of LIBDV between ELs and MOs,which is quantitatively investigated based on the LIBDVs collected from the *** breakdown mechanism transition phenomenon between streamer initiation dominated breakdown and streamer propagation dominated breakdown has been reviewed ***,the transition field factor boundaries to observe the polarity effect on LIBDVs are taken at around 20 for ELs and 10 for ***,the transition field factor boundaries to observe the LIBDV distinctions between ELs and MOs are about 109 and 14 under positive and negative lightning impulse,*** systematic analysis and interpretation on the transition field factor boundaries among different phenomena can provide insights on insulation design of ELs filled power transformers.

关键词： field lightning breakdown

Supernova 1987A's Keyhole: A Long-lived Jet-pair in the Final Explosion Phase of Core-collapse Supernovae

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

Research in Astronomy and Astrophysics 2024年第7期24卷 92-97页

作者： Noam Soker department of Physics Technion

I further study the manner by which a pair of opposite jets shape the “keyhole” morphological structure of the core-collapse supernova(CCSN) SN 1997A, now the CCSN remnant(CCSNR) 1987A. By doing so, I strengthen the claim that the jittering-jet explosion mechanism accounts for most, likely all, CCSNe. The “keyhole” structure comprises a northern low-intensity zone closed with a bright rim on its front and an elongated low-intensity nozzle in the south. This rim-nozzle asymmetry is observed in some cooling flow clusters and planetary nebulae that are observed to be shaped by jets. I build a toy model that uses the planar jittering jets pattern, where consecutive pairs of jets tend to jitter in a common plane, implying that the accreted gas onto the newly born neutron star at the late explosion phase flows perpendicular to that plane. This allows for a long-lived jet-launching episode. This long-lasting jet-launching episode launches more mass into the jets that can inflate larger pairs of ears or bubbles,forming the main jets' axis of the CCSNR that is not necessarily related to a possible pre-collapse core rotation. I discuss the relation of the main jets' axis to the neutron star's natal kick velocity.

关键词： (stars:) supernovae: general (stars:) supernovae: individual (SN 1987A) ISM: supernova remnants stars: jets stars: massive

Tuning structural,electrical,dielectric and magnetic properties of Mg-Cu-Co ferrites via dysprosium(Dy^(3+))doping

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Rare Earths 2024年第1期42卷 137-146,I0005页

作者： Maria Akhtar M.S.Hasan Nasir Amin N.A.Morley Muhammad Imran Arshad department of Physics Government College UniversityFaisalabad38000Pakistan department of Physics The University of Lahore53700Pakistan department of Materials Science and Engineering The University of SheffieldS13JDUK department of Physics&Astronomy University College LondonUK

In current research work,Dy3+substituted Mg0.5Cu0.25Co0.25Fe2-xDyxO4(0.0≤x≤0.04 with the step interval of 0.01)soft ferrites were synthesized by the sol-gel auto combustion *** prepared samples were characterized by the techniques using X-ray diffraction(XRD),scanning electron microscopy(SEM),energy dispersive X-ray spectroscopy(EDS),Fourier transform infrared(FTIR)spectroscopy,curre nt-voltage(Ⅰ-Ⅴ)measurement,LCR meter,vibrating sample magnetometer(VSM)and *** data reveal that the average crystallite size is 49.71 nm and the lattice constant is 0.83703 nm for sample x=*** non-uniform grain growth was demonstrated by micrographs and impurity-free elemental composition was observed from EDX *** DC resistivity has an increasing and decreasing trend in ferromagnetic and paramagnetic regions with an increase in ***,the high resistivity is observed with the order of 1010Ω·cm,and the activation energy is 0.944 eV for samples x=*** dielectric parameters including dielectric constant,dielectric losses,and impedance gradually decrease with the increase in frequency from 8 Hz to 8 *** minimum dielectric loss at high frequency is found for sample x=*** coercivity(Hc)and saturation magnetization(Ms)are found in the ranges of 520.82-544.02 Oe and 20.5841-21.1473 emu/g,*** observations confirm that dysprosium(x=0.03)doped MCC-soft ferrites may be applicable in transformer cores,microwave absorbance,and telecommunication devices.

关键词： Soft ferrites DC resistivity Dielectric loss Impedance Coercivity Rare earths

维普期刊数据库

Assessing the energy saving potential of using adaptive setpoint temperatures:The case study of a regional adaptive comfort model for Brazil in both the present and the future

在线全文

学校读者我要写书评

暂无评论

Building Simulation 2024年第3期17卷 459-482页

作者： Daniel Sánchez-García David Bienvenido-Huertas Carlos Rubio-Bellido Ricardo Forgiarini Rupp department of Electrical Engineering University Carlos III of MadridMadridSpain department of Building Simulation ZEROCEM SLSevilleSpain department of Building Constructions University of GranadaGranadaSpain department of Building Constructions II University of SevilleSevilleSpain Section of Design for Sustainability Department of Civil and Mechanical EngineeringTechnical University of DenmarkKgs.LyngbyDenmark

It has been found in recent years that using setpoint temperatures based on adaptive thermal comfort models is a successful method of energy *** studies using adaptive setpoint temperatures incorporate international models from ASHRAE Standard 55 and *** study,however,has instead considered a regional Brazilian adaptive comfort *** study investigates the energy demand arising from the use of a local Brazilian comfort model in order to assess the energy implications from the use of the worldwide ASHRAE Standard 55 adaptive model and various fixed setpoint *** of Brazil’s climate zones,full air-conditioning,mixed-mode building operating modes,present-day climate change scenarios,and future scenarios—specifically Representative Concentration Pathways(RCP)2.6,4.5,and 8.5 for the years 2050 and 2100—have all been taken into account in building energy *** use of adaptive setpoint temperatures based on the Brazilian local model considering mixed-mode has been found to significantly reduce energy consumption when compared to static setpoint temperatures(average energy-saving values ranging from 52%to 58%)and the ASHRAE 55 adaptive model(average values ranging from 15%to 21%).Considering climate change and the mixed-mode Brazilian model,the overall energy demand for the three groups of climatic zones(annual average outdoor temperatures≤21℃,>21 and≤25℃and>25℃)ranged between 2%decrease and 5%increase,4%and 27%increase,and 13%and 45%increase,*** is concluded as a consequence that setting setpoint temperatures based on the Brazilian local adaptive comfort model is a very efficient energy-saving method.

关键词： adaptive thermal comfort building energy simulation energy efficiency climate change adaptive setpoint temperatures local comfort mode

Proposal for a realtime Einstein-synchronization-defined satellite virtual 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 2024年第7期33卷 268-276页

作者：严晨皓汤雪逸王时光孟李皎悦孙海媛何奕彬王力军 department of Precision Instrument Tsinghua UniversityBeijing 100091China department of Physics Tsinghua UniversityBeijing 100091China

Realization of high performance satellite onboard clock is vital for various positioning, navigation, and timing applications. For further improvement of the synchronization-based satellite time and frequency references, we propose a geosynchronous(GEO) satellite virtual clock concept based on ground–satellite synchronization and present a beacon transponder structure for its implementation(scheduled for launch in 2025), which does not require atomic clocks to be mounted on the satellite. Its high performance relies only on minor modifications to the existing transponder structure of GEO satellites. We carefully model the carrier phase link and analyze the factors causing link asymmetry within the special relativity. Considering that performance of such synchronization-based satellite clocks is primarily limited by the link's random phase noise, which cannot be adequately modeled, we design a closed-loop experiment based on commercial GEO satellites for pre-evaluation. This experiment aims at extracting the zero-means random part of the ground-satellite Ku-band carrier phase via a feedback loop. Ultimately, we obtain a 1σ value of 0.633 ps(two-way link), following the Gaussian distribution. From this result, we conclude that the proposed real-time Einstein-synchronization-defined satellite virtual clock can achieve picosecond-level replication of onboard time and frequency.

关键词： Einstein synchronization satellite virtual clock geosynchronous satellite carrier phase

维普期刊数据库

On the analytical soliton approximations to fractional forced Korteweg–de Vries equation arising in fluids and plasmas using two novel techniques

在线全文

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2024年第08期76卷 3-12页

作者： Weaam Alhejaili Emad A Az-Zo'bi Rasool Shah S A El-Tantawy department of Mathematical Sciences College of Science Princess Nourah bint Abdulrahman University department Mathematics and Statistics Mutah University department of Computer Science and Mathematics Lebanese American University department of Physics Faculty of Science Port Said University department of Physics Faculty of Science Al-Baha University

The current investigation examines the fractional forced Korteweg–de Vries(FF-KdV) equation,a critically significant evolution equation in various nonlinear branches of science. The equation in question and other associated equations are widely acknowledged for their broad applicability and potential for simulating a wide range of nonlinear phenomena in fluid physics, plasma physics, and various scientific domains. Consequently, the main goal of this study is to use the Yang homotopy perturbation method and the Yang transform decomposition method, along with the Caputo operator for analyzing the FF-KdV equation. The derived approximations are numerically examined and discussed. Our study will show that the two suggested methods are helpful, easy to use, and essential for looking at different nonlinear models that affect complex processes.

关键词： Caputo operator forced fractional KdV equation solitons Yang homotopy perturbation method Yang transform decomposition method