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Intra-beam scattering and beam lifetime in a candidate lattice of the soft X-ray diffraction-limited storage ring for the upgraded SSRF

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Nuclear Science and Techniques 2021年第8期32卷 57-66页

作者： Xin-Zhong Liu shun-Qiang Tian Xu Wu meng Wang Zhen-Tang Zhao Shanghai Institute of Applied Physics Chinese Academy of SciencesShanghai 201800China University of Chinese Academy of Sciences Beijing 100049China Shanghai Advanced Research Institute Chinese Academy of SciencesShanghai 201204China Shanghai University Shanghai 200444China

New-generation synchrotron light sources are being designed and operated worldwide to provide brighter radiation by reducing the beam emittance to X-ray diffraction ***-beam scattering(IBS)and Touschek scattering in such facilities are significant and require attention because of their ultra-low ***,cure strategies need to be carefully studied to obtain highquality photon *** the Shanghai Synchrotron Radiation Facility Upgrade(SSRF-U),a candidate lattice of the storage ring,reaching the soft X-ray diffraction limit,was designed and presented for the first time in this *** emittance growth and beam lifetime in the SSRF-U storage ring were studied using particle simulations for a series of different machine *** gains with RF frequencies of 100 MHz and 500 MHz were *** with a better filling pattern,a more suitable RF frequency was adopted in the *** variations in the equilibrium beam emittance with beam coupling and bunch-lengthening were identified using *** beam coupling and required bunch-lengthening for the SSRF-U storage ring were thus *** fitness of the beam energy in the SSRF-U was subsequently assessed using the obtained ***,the Touschek scattering and beam lifetime were calculated,and an acceptable total beam lifetime was obtained.

关键词： Diffraction-Limited Storage Ring(DLSR) Shanghai Synchrotron Radiation Facility Upgrade(SSRFU) Intra-Beam Scattering(IBS) Touschek scattering Beam lifetime

Has LIGO detected primordial black hole dark matter?——tidal disruption in binary black hole formation

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Research in Astronomy and Astrophysics 2020年第11期20卷 303-311页

作者： yuan Gao Xiao-Jia Zhang meng Su Department of Physics The University of Hong KongHong Kong SARChina Department of Earth Sciences The University of Hong KongHong Kong SARChina Department of Physics and Laboratory for Space Research The University of Hong KongHong Kong SARChina

The frequent detection of binary mergers of^30 M⊙black holes(BHs)by the Laser Interferometer Gravitational-Wave Observatory(LIGO)rekindled researchers’interest in primordial BHs(PBHs)being dark matter(DM).In this work,we investigated PBHs distributed as DM with a monochromatic mass of 30 M⊙and examined the encounter-capture scenario of binary formation,where the densest central region of DM halo ***,we paid special attention to the tidal effect by the supermassive black hole(SMBH)*** doing so,we discovered a necessary tool called loss zone that complements the usage of loss *** found that the tidal effect is not prominent in affecting binary formation,which also turned out to be insufficient in explaining the totality of LIGO’s event rate estimation,especially due to a microlensing event constraining the DM fraction in PBH at the mass of interest from near unity to an order ***,an early-universe binary formation scenario proves so prevailing that the LIGO signal in turn constrains the PBH fraction below one ***,people should put more faith in alternative PBH windows and other DM candidates.

关键词： black hole physics dark matter gravitational waves quasars supermassive black holes

Primordial black holes generated by the non-minimal spectator field

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Science China(Physics,Mechanics & Astronomy) 2023年第8期66卷 42-50页

作者： De-Shuang meng Chen yuan Qing-Guo Huang CAS Key Laboratory of Theoretical Physics Institute of Theoretical PhysicsChinese Academy of SciencesBeijing 100190China School of Physical Sciences University of Chinese Academy of SciencesBeijing 100049China School of Fundamental Physics and Mathematical Sciences Hangzhou Institute for Advanced StudyUniversity of Chinese Academy of SciencesHangzhou310024China

We improve and generalize the non-minimal curvaton model originally proposed in arXiv:2112.12680 to a model in which a spectator field non-minimally couples to an inflaton field and the power spectrum of the perturbation of spectator field at small scales is dramatically enhanced by the sharp feature in the form of non-minimal *** or after the end of inflation,the perturbation of the spectator field is converted into curvature perturbation and leads to the formation of primordial black holes(PBHs).Furthermore,for example,we consider three phenomenological models for generating PBHs with mass function peaked at~10^(-12) M_(⊙)and representing all the cold dark matter in our universe and find that the scalar induced gravitational waves generated by the curvature perturbation can be detected by the future space-borne gravitational-wave detectors such as Taiji,Tian Qin,and LISA.

关键词： primordial black holes non-minimal spectator field cold dark matter

Performance Evaluation with Improved Receiver Design for Asynchronous Coordinated Multipoint Transmissions

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Chinese Journal of Electronics 2016年第2期25卷 372-378页

作者： CAO yuan WEN Yinghong meng Xiangyang XU Wei National Engineering Research Center of Rail Transportation Operation and Control System. Beijing Jiaotong University School of Electronic and Information Engineering Beijing Jiaotong University National Mobile Communications Research Lab. Southeast University

Joint transmission is one of the ma jor transmission schemes in Coordinated multipoint(Co MP)transmission/reception systems for Long term evolutionadvanced(LTE-A). Due to different distances between User equipments(UE) and Base stations(BS), signals are not able to arrive at the receiver with perfect synchronization, which implies that the reception at UE is asynchronous. This paper presents an evaluation on asynchronous UE reception in multi-cell downlink joint transmission systems using our LTE-based Co MP ***, due to asynchronous reception, we propose an improved reception strategy to mitigate the interference which compensate for Rx timing difference on Joint transmission(JT) Co MP systems. Simulation results show that the per-subband global precoding scheme widely used in the Co MP system is considerably sensitive to asynchronous reception since the performance is dominated by the subcarrier used for precoding vector calculation. It is verified that our proposed solution is able to achieve significant improvements under asynchronous reception.

关键词： Joint transmission Asynchronous reception Global precoding CoMP

Integrated assessment of river health based on water quality, aquatic life and physical habitat

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Journal of Environmental Sciences 2009年第8期21卷 1017-1027页

作者： meng Wei ZHANG Nan ZHANG yuan ZHENG Binghui River and Costal Environmental Research Center China Research Academy of Environment Science Beijing 100012 China Key Laboratory of Water and Sediment Sciences College of Water Sciences Beijing Normal University Beijing 100875 China

The health conditions of Liao River were assessed using 25 sampling sites in April 2005, with water quality index, biotic index and physical habitat quality index. Based on the method of cluster analysis （CA） for water quality indices, it revealed that heavily polluted sites of Liao River are located at estuary and mainstream. The aquatic species surveyed were attached algae and benthic invertebrates. The result showed that the diversity and biomass of attached algae and benthic index of biotic integrity （B-IBI） were degrading as the chemical and physical quality of water bodies deteriorating. Physiochemical parameters, BODs, CODcr, TN, TP, NH3-N, DO, petroleum hydrocarbon and conductivity, were statistically analyzed with principal component analysis and correlation analysis. The statistical results were incorporated into the integrated assessing water quality index, combining fecal coliform count, attached algae diversity, B-IBI and physical habitat quality score. A comprehensive integrated assessing system of fiver ecological health was established. Based on the systimetic assessment, the assessed sites are categorized into 9 ＂healthy＂ and ＂sub-healthy＂ sites and 8 ＂sub-sick＂ and ＂sick＂ sites.

关键词： Liao River river health assessment benthic-index of biotic integrity water quality physical habitat conditions

A radical addition and cyclization relay promoted by Mn(OAc)_(3)·2 H_(2)O:Synthesis of 1,2-oxaphospholoindoles and mechanistic study

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Chinese Chemical Letters 2021年第6期32卷 1915-1919页

作者： meng-meng Xu Lu-Yao Kou Xiao-Guang Bao Xiao-Ping Xu shun-Jun Ji Key Laboratory of Organic Synthesis of Jiangsu Province College of ChemistryChemical Engineering and Materials Science&Collaborative Innovation Center of Suzhou Nano Science and TechnologySoochow UniversitySuzhou 215123China

Novel and efficient Mn(OAc)_(3)·2 H_(2)O promoted radical addition-[4+1]cyclization relay of 3-indolymethanols and phosphites was disclosed,which afforded 1,2-oxaphospholoindole derivatives in moderate to good *** on the experimental and computational studies,a mechanism involving radical addition and intramolecular cyclization cascade was proposed.

关键词： 3-Indolymethanol Dual role of Mn(OAc)_(3) Four-atom building blocks Valuable products DFT calculations

Resilient tightly coupled INS/UWB integration method for indoor UAV navigation under challenging scenarios

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Defence Technology（防务技术） 2023年第4期22卷 185-196页

作者： Qian meng Yang Song Sheng-ying Li yuan Zhuang Key Laboratory of Micro-Inertial Instrument and Advanced Navigation Technology Southeast UniversityNanjing210096China Department of Mechanical Engineering Hong Kong Polytechnic UniversityHong KongChina State Key Laboratory of Information Engineering in Surveying Mapping and Remote SensingWuhan UniversityWuhanChina

Based on the high positioning accuracy,low cost and low-power consumption,the ultra-wide-band(UWB)is an ideal solution for indoor unmanned aerial vehicle(UAV)localization and ***,the UWB signals are easy to be blocked or reflected by obstacles such as walls and furniture.A resilient tightly-coupled inertial navigation system(INS)/UWB integration is proposed and implemented for indoor UAV navigation in this paper.A factor graph optimization(FGO)method enhanced by resilient stochastic model is established to cope with the indoor challenging *** deal with the impact of UWB non-line-of-sight(NLOS)signals and noise uncertainty,the conventional neural net-works(CNNs)are introduced into the stochastic modelling to improve the resilience and reliability of the *** on the status that the UWB features are limited,a‘two-phase'CNNs structure was designed and implemented:one for signal classification and the other one for measurement noise *** proposed resilient FGO method is tested on flighting UAV platform under actual indoor challenging *** to classical FGO method,the overall positioning errors can be decreased from about 0.60 m to centimeter-level under signal block and reflection *** superiority of resilient FGO which effectively verified in constrained environment is pretty important for positioning accuracy and integrity for indoor navigation task.

关键词： Unmanned aerial vehicle(UAV) Resilient navigation Indoor positioning Factor graph optimization Ultra-wide band(UWB)

Interaction between microporous magnesia castable and 38CrMoAl steel

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Journal of Iron and Steel Research International 2023年第3期30卷 516-524页

作者： Cheng yuan Yu Liu Guang-qiang Li Yong-shun Zou Ao Huang The State Key Laboratory of Refractories and Metallurgy Wuhan University of Science and TechnologyWuhan 430081HubeiChina Key Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of Education Wuhan University of Science and TechnologyWuhan 430081HubeiChina Hubei Provincial Key Laboratory for New Processes of Ironmaking and Steelmaking Wuhan University of Science and TechnologyWuhan 430081HubeiChina

The microporous magnesia refractory shows a promising application prospect as tundish lining due to excellent thermal insulation and slag *** effect of interaction between microporous magnesia castable and 38CrMoAl steel containing 0.876 wt.%Al on the cleanliness of 38CrMoAl steel was studied and compared with that of fused magnesia *** results show that the micropores in the microporous magnesia castable can promote the formation of dense and continuous MgO-Al_(2)O_(3)layer,which can inhibit the further pollution of molten steel by refractories,whereas the MgO-Al_(2)O_(3)layer formed in test of fused magnesia castable is not *** 30 min holding,the total oxygen content in the steel samples for the test of microporous magnesia castable is only 42.2%of that for the test of fused magnesia *** inclusions in the steel samples for the test of microporous magnesia castable are also less than those for the test of fused magnesia *** shows that microporous magnesia castable is a promising tundish refractory for the preparation of clean high-Al steel.

关键词： Microporous magnesia castable Fused magnesia castable High-Al steel Cleanliness Tundish lining refractory

Bionic stab-resistant body armor based on triangular pyramid structure

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Defence Technology（防务技术） 2021年第3期17卷 792-799页

作者： Ya-xin Guo meng-qi yuan Xin-ming Qian State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing100081China

A stab-resistant substrate was designed and realized with a triangular pyramidal structure, inspired by the biological armor model in nature. The stab-resistance behavior and dynamic response mechanisms were studied through numerical simulation and experimental testing of a knife impacting a substrate,and an optimal structural design was obtained accordingly, with a tilted angle of 22.5and optimal thickness of 1.2 mm. It was shown that the triangular pyramidal structure generated twice the internal energy of the knife than the flat substrate due to the dispersing effect of the structure. The force parallel to the inclination caused a significant scratch on the substrate surface, while the force perpendicular caused obvious substrate deformation. A new riveting method was used to form the total layer, which passed the GA 68-2008 standard. The stab-resistant clothing coupled with the reduced wearing burden could provide effective protection and avoid fatal injuries on security personnel working in dangerous environments. The method provided may enlighten the future design and manufacturing of stabresistant clothing.

关键词： Stab resistant Impact behavior Body armor Finite element analysis