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Influence of pressure disturbance wave on dynamic response characteristics of liquid film seal for multiphase pump

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Petroleum Science 2024年第3期21卷 2048-2065页

作者： Qing-Ping Li Jin-ya Zhang Jia-Xiang Zhang Yong-xue Zhang CNOOC Research Institute Company Limited Beijing100028China State Key Laboratory of Natural gas Hydrate Beijing100028China College of Mechanical and Transportation Engineering China University of PetroleumBeijing2249China

Slug flow or high gVF(gas Volume Fraction)conditions can cause pressure disturbance waves and alternating loads at the boundary of mechanical seals for multiphase pumps,endangering the safety of multiphase pump *** mechanical seal model is simplified by using periodic boundary conditions and numerical calculations are carried out based on the Zwart-gerber-Belamri cavitation ***(User Define Function)programs such as structural dynamics equations,alternating load equations,and pressure disturbance equations are embedded in numerical calculations,and the dynamic response characteristics of mechanical seal are studied using layered dynamic mesh *** results show that when the pressure disturbance occurs at the inlet,as the amplitude and period of the disturbance increase,the film thickness gradually *** the fundamental reason for the hysteresis of the film thickness change is that the pressure in the high-pressure area cannot be restored in a timely *** maximum value of leakage and the minimum value of axial velocity are independent of the disturbance period and determined by the disturbance *** mutual interference between enhanced waves does not have a significant impact on the film thickness,while the front wave in the attenuated wave has a promoting effect on the subsequent film thickness changes,and the fluctuation of the liquid film cavitation rate and axial velocity under the attenuated wave condition deviates from the initial *** with pressure disturbance conditions,alternating load conditions have a more significant impact on film thickness and *** actual operation,it is necessary to avoid alternating load conditions in multiphase pump mechanical seals.

关键词： Multiphase pump Liquid film seal Pressure disturbance wave Dynamic response characteristics

Enhancing reversible hydrogen storage performance of 2LiBH4–MgH2 via in-situ building heterogeneous nucleation sites

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Rare Metals 2024年第9期43卷 4367-4376页

作者： Wei Chen ya-Hui Sun Tian Xu xue-Bin Yu guang-Lin Xia Department of Materials Science Fudan University

2LiBH4-MgH2composite is one of the most attractive reactive hydride composites with a theoretic hydrogen capacity of 10.8 wt%.However,the large nucleation restriction of MgB2during the second step of dehydrogenation results in sluggish hydrogen storage kinetics and high operating temperature,which hinders its practical application as on-board hydrogen storage ***,Al3Ti doped Al nanoparticles （AT NPs） are prepared by a facile chemical reduction reaction to improve the hydrogen storage performance of *** the initial H2desorption process,MgAlB4and TiB2that have identical crystal structure and low d-value mismatch with MgB2resulting from the reaction between AT NPs and 2LiBH4-MgH2composite serve as effective nucleation sites for the formation of *** a result,the apparent activation energy of the two-step H2desorption of AT NPs doped 2LiBH4-MgH2composite are notably decreased to （110.0±5.9） and（119.6±1.4） kJ·mol-1,which is 55.5 and 33.5 kJ·mol-1lower than that of the undoped *** importantly,a reversible hydrogen storage capacity of 9.2 wt%after 10cycles of H2desorption and adsorption could be achieved,corresponding to a capacity retention rate of 99%.The building of reactive bimetallic catalyst towards in situ formation of heterogeneous nucleation sites provides a new strategy for improving the hydrogen storage performance of reactive hydride composites.

关键词： Catalytic effects Heterogeneous nucleation Reactive hydride composites Reversible hydrogen storage

Atorvastatin, etanercept and the nephrogenic cardiac sympathetic remodeling in chronic renal failure rats

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Journal of geriatric Cardiology 2024年第4期21卷 443-457页

作者： Jing-Yue XU Zheng-Kai xue ya-Ru ZHANg Xing LIU xue ZHANg Xi yaNg Tong LIU Kang-Yin CHEN Tianjin Key Laboratory of Ionic-Molecular Function of Cardiovascular Disease Department of CardiologyTianjin Institute of Cardiologythe Second Hospital of Tianjin Medical UniversityTianjinChina

BACKgROUND Chronic renal failure(CRF) patients are predisposed to arrhythmias, while the detailed mechanisms are unclear. We hypothesized the chronic inflammatory state of CRF patients may lead to cardiac sympathetic remodeling, increasing the incidence of ventricular arrhythmia(VA) and sudden cardiac death. And explored the role of atorvastatin and etanercept in this *** A total of 48 rats were randomly divided into sham operation group(Sham group), CRF group, CRF + atorvastatin group(CRF + statin group), and CRF + etanercept group(CRF + rhTNFR-Fcgroup). Sympathetic nerve remodeling was assessed by immunofluorescence of growth-associated protein 43(gAP-43) and tyrosine hydroxylase positive area fraction. Electrophysiological testing was performed to assess the incidence of VA by assessing the ventricular effective refractory period and ventricular fibrillation threshold. The levels of tumor necrosis factor-alpha(TNF-α) and interleukin-1beta were determined by Western blotting and enzyme-linked immunosorbent *** Echocardiogram showed that compared with the Sham group, left ventricular end-systolic diameter and ventricular weight/body weight ratio were significantly higher in the CRF group. Hematoxylin-eosin and Masson staining indicated that myocardial fibers were broken, disordered, and fibrotic in the CRF group. Western blotting, enzyme-linked immunosorbent assay,immunofluorescence and electrophysiological examination suggested that compared with the Sham group, gAP-43 and TNF-α proteins were significantly upregulated, gAP-43 and tyrosine hydroxylase positive nerve fiber area was increased, and ventricular fibrillation threshold was significantly decreased in the CRF group. The above effects were inhibited in the CRF + statin group and the CRF + *** In CRF rats, TNF-α was upregulated, cardiac sympathetic remodeling was more severe, and the nephrogenic cardiac sympathetic remodeling existed. Atorvastatin and etanercept c

关键词： remodeling cardiac inhibited

Structural transformation from Waugh-type to Keggin-type polyoxomolybdate-based crystalline material for photo/electrocatalysis

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Rare Metals 2024年第5期43卷 2241-2250页

作者： Pei-Sen Wang Zi-Tong Wang ya-ya Tan Peng Chen xue-Cheng Zhang Lu-Nan Zhang Yong-ge Wei Lu-Bin Ni School of Chemistry and Chemical Engineering Yangzhou UniversityYangzhou 225002China Key Lab of Organic Optoelectronics and Molecular Engineering of Ministry of Education Department of ChemistryTsinghua UniversityBeijing 100084China State Key Laboratory of Natural and Biomimetic Drugs Peking UniversityBeijing100191China

An inorganicDorganic hybrid crystalline material(SiMo_(12)O_(40))[Cu(2,2'-bipy)_(2)]_(2)·2H_(2)O(Complex 1,2,2'-bipy=2,2'-bipyridine)was synthesized for the first time by using 2,2'-bipy and transition metal copper to convert Waugh-type polyoxometalate[MnMo_(9)O_(3)_(2)]_(6-)into a Keggin polyoxometalate structure[SiMo_(12)O_(40)]^(4-)under hydrothermal conditions in glass *** crystal tests and a series of characterizations were carried out on Complex *** structure of Complex 1 is composed of[SiMo_(12)O_(40)]^(4-)and[Cu^(Ⅱ)(2,2'-bipy)_(2)]^(2+).The five-coordinated Cu is connected to two 2,2'-bipy through CuDN bonds,forming an approximately square ***,Complex 1 exhibited good photocatalytic performance for methylene blue degradation and electrocatalytic nitrite reduction properties simultaneously.

关键词： Polyoxometalates Inorganic-organic hybrid materials Photocatalytic Electrocatalytic

Research on feed-pulse collaborative control method in micro-electrical discharge machining

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Advances in Manufacturing 2024年第2期12卷 270-287页

作者： Qiang gao ya-Ou Zhang xue-Cheng Xi Yuan-Ding Wang Xiao-Fei Chen Wan-Sheng Zhao School of Mechanical Engineering Shanghai Jiao Tong UniversityShanghai200240People’s Republic of China State Key Laboratory of Mechanical System and Vibration Shanghai200240People’s Republic of China Shanghai Institute of Space Propulsion Shanghai201112People’s Republic of China

Reducing the short-circuit rate and increasing the effective discharge rate are important targets for improving the servo control effect of micro-electrical discharge machining(micro-EDM),as these two indicators are closely related to the machining efficiency and *** this study,a feed-pulse collaborative control(FPCC)method is proposed for micro-EDM based on two dimensions(space and time).In the spatial dimension,a feed control strategy with a discharge holding process is ***,in the time dimension,a forward-looking pulse control strategy is adopted,in which the pulse interval is adjusted based on a sequence analysis of feed commands and discharge *** experiments are carried out to determine the key parameters used in this method,including the discharge holding threshold and pulse interval adjustment value(T_(off_(adj))).The feed smoothness and discharge sufficiency analyses of the experimental results show that compared to the traditional double threshold average voltage method,the FPCC method reduces the number of long-distance retreats by 64%and improves the effective discharge time by 40%.

关键词： Micro-electrical discharge machining(micro-EDM) Electrode feed control Discharge pulse control Machining surface quality

Plutonium utilization in a small modular molten-salt reactor based on a batch fuel reprocessing scheme

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Nuclear Science and Techniques 2024年第4期35卷 15-28页

作者： xue-chao Zhao Rui yan gui-Feng Zhu ya-Fen Liu Jian guo Xiang-Zhou Cai yang Zou Shanghai Institute of Applied Physics Chinese Academy of SciencesShanghai 201800China CAS Innovative Academies in TMSR Energy System Chinese Academy of SciencesShanghai 201800China University of Chinese Academy of Sciences Beijing 100049China

A molten salt reactor(MSR)has outstanding features considering the application of thorium fuel,inherent safety,sustainability,and resistance to ***,fissile material^(233)U is significantly rare at the current stage,thus it is difficult for MSR to achieve a pure thorium-uranium fuel ***,using plutonium or enriched uranium as the initial fuel for MSR is more *** this study,we aim to verify the feasibility of a small modular MSR that utilizes plutonium as the starting fuel(SM-MSR-Pu),and highlight its advantages and ***,the structural design and fuel management scheme of the SM-MSR-Pu were ***,the neutronic characteristics,such as the graphite-irradiation lifetime,burn-up performance,and coefficient of temperature reactivity were calculated to analyze the physical characteristics of the *** results indicate that plutonium is a feasible and advantageous starting fuel for a SM-MSR;however,there are certain shortcomings that need to be *** a 250 MWth SM-MSR-Pu,approximately 288.64 kg^(233)U of plutonium with a purity of greater than 90% is produced while 978.00 kg is burned every ten *** temperature reactivity coefficient decreases from -4.0 to -6.5 pcm K^(-1) over the 50-year operating time,which ensures a long-term safe ***,the amount of plutonium and accumulation of minor actinides(MAs)would increase as the burn-up time increases,and the annual production and purity of^(233)U will *** achieve an optimal burn-up performance,setting the entire operation time to 30 years is ***,more than 3600 kg of plutonium eventually accumulate in the *** research is required to effectively utilize this accumulated plutonium.

关键词： Molten salt fuel Plutonium utilization ^(233)U TRUs mole fraction Temperature feedback coefficient

ground state of Rydberg-dressed Bose gas confined in a toroidal trap

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Communications in Theoretical Physics 2024年第1期76卷 29-35页

作者： Lin-xue Wang Hong-Li yang Hui Liu Si-Lin Chen ya-Jun Wang Xiao-Fei Zhang Department of Physics School of Physics and Information ScienceShaanxi University of Science and TechnologyXi'an 710021China Department of Basic Sciences Air Force Engineering UniversityXi'an 710051China

The experimental realization of Rydberg dressing technology in ultracold atomic systems provides another superior platform for studying novel states of matter and macroscopic quantum *** this work,based on the mean-field theory,we have investigated the ground-state phases of a two-component Bose–Einstein condensate with Rydberg interaction and confined in a toroidal *** effects of the Rydberg interaction and external potential,especially the Rydberg blockade radius,on the ground-state structure of such a system have been investigated in full parameter *** results show that the Rydberg blockade radius,which can be regarded as another controllable parameter,can be used to obtain a variety of ground-state *** interestingly,it is found that for weak Rydberg interactions,the Rydberg blockade radius breaks the spontaneous rotational symmetry of the system,leading to the formation of a discrete unit cell *** strongly interacting cases,it can be used to realize different orders of discrete rotational symmetry breaking.

关键词： Bose-Einstein condensate Rydberg dressing toroidal trap

Cracking on a nickel-based superalloy fabricated by direct energy deposition

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China Foundry 2024年第4期21卷 311-318页

作者： xue Zhang ya-hang Mu Liang Ma Jing-jing Liang Yi-zhou Zhou Xiao-feng Sun Jin-guo Li School of Materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China Shi-changxu Innovation Center for Advanced Materials Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering Northeastern UniversityShenyang 110819China

Cracks have consistently been a significant challenge limiting the development of additive manufactured nickel-based *** is essential to investigate the location of cracks and their forming *** study extensively examines the impact of solidification process,microstructural evolution,and stress concentration on crack initiation during direct energy deposition(DED).The results emphasize that the crack formation is significantly related to large-angle grain boundaries,rapid cooling *** caused by large-angle grain boundaries and a fast-cooling rate predominantly appear near the edge of the deposited *** cracks are more likely to form near the top of the deposited sample,due to the presence ofγ/γ'*** secondary dendritic arm and the carbides in the interdendritic regions can obstruct liquid flow during the final stage of solidification,which results in the formation of solidification cracks and *** work paves the way to avoid cracks in nickel-based superalloys fabricated by DED,thereby enhancing the performance of superalloys.

关键词： location cracks direct energy deposition nickel-based superalloys

Research on shell-side heat and mass transfer with multi-component in LNg spiral-wound heat exchanger under sloshing conditions

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Petroleum Science 2024年第2期21卷 1333-1345页

作者： xue-Ping Du guang-Lei Yu ya-Cheng Xu Zhi-Jie Chen Nai-Liang Li Huan-guang Wang School of Low-carbon Energy and Power Engineering China University of Mining and TechnologyXuzhou221116JiangsuChina Key Laboratory of Thermo-Fluid Science and Engineering MOEXi'an Jiaotong UniversityXi'an710049ShaanxiChina Xi'an Aerospace Propulsion Test Technology Institute Xi'an710100ShaanxiChina

The spiral-wound heat exchanger(SWHE) is the primary low-temperature heat exchanger for large-scale LNg plants due to its high-pressure resistance, compact structure, and high heat exchange efficiency. This paper studied the shell-side heat and mass transfer characteristics of vapor-liquid two-phase mixed refrigerants in an SWHE by combining a multi-component model in FLUENT software with a customized multicomponent mass transfer model. Besides, the mathematical model under the sloshing condition was obtained through mathematical derivation, and the corresponding UDF code was loaded into FLUENT as the momentum source term. The results under the sloshing conditions were compared with the relevant parameters under the steady-state condition. The shell-side heat and mass transfer characteristics of the SWHE were investigated by adjusting the component ratio and other working conditions. It was found that the sloshing conditions enhance the heat transfer performance and sometimes have insignificant effects. The sloshing condition is beneficial to reduce the flow resistance. The comprehensive performance of multi-component refrigerants has been improved and the improvement is more significant under sloshing conditions, considering both the heat transfer and pressure *** results will provide theoretical support for the research and design of multi-component heat and mass transfer enhancement of LNg SWHE under ocean sloshing conditions.

关键词： Spiral-wound heat exchanger Sloshing conditions Two-phase flow Multi-component Heat and mass transfer