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Pre-heating temperature induced flowability and wax deposition characteristics of crude oil adding wax inhibitors

Petroleum Science 2023年第4期20卷 2468-2478页

作者： Bo Yao Hao-Ran Zhu bao-dong yan Chuan-Xian Li Fei yang Guang-Yu Sun Hong-Bo Zeng College of Pipeline and Civil Engineering China University of PetroleumQingdaoShandong266580People's Republic of China Department of Chemical and Materials Engineering University of AlbertaEdmontonABT6G 1H9Canada School of Petroleum Engineering Changzhou UniversityChangzhouJiangsu213164People's Republic of China China Oil&Gas Pipeline Network Corporation Beijing100020China

This paper investigated the effects of pre-heating treatment temperatures(T_(pre))on the flowability and wax deposition characteristics of a typical waxy crude oil after adding wax inhibitors.It is found that there is little difference in wax precipitation exothermic characteristics of crude oils at different T_(pre),as well as the wax crystal solubility coefficient in the temperature range of 25-30℃.For the undoped crude oil,the flowability after wax precipitation gets much improved and the wax deposition is alleviated as T_(pre)increasing.At T_(pre)=50℃,the viscosity and wax deposition rate of crude oil adding wax inhibitors are higher than those of the undoped crude oil.When the T_(pre)increases to 60,70,and 80℃,the flowability of the doped crude oil are largely improved and the wax deposition is suppressed with the T_(pre)increase,but the wax content of wax deposit increases gradually.It is speculated that,on the one hand,the T_(pre)increase helps the dispersion of asphaltenes into smaller sizes,which facilitates the co-crystallization with paraffin waxes and generates more aggregated wax crystal flocs.This weakens the low-temperature gel structure and increases the solid concentration required for the crosslink to form the wax deposit.On the other hand,the decrease in viscosity increases the diffusion rate of wax molecules and accelerates the aging of wax deposits.The experimental results have important guiding significance for the pipeline transportation of doped crude oils.

关键词： Pre-heating treatment Wax inhibitor Flowability Wax deposition Waxy crude oil

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Improving fatigue properties of normal direction ultrasonic vibration assisted face grinding Inconel 718 by regulating machined surface integrity

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International Journal of Extreme Manufacturing 2024年第3期6卷 458-475页

作者： Nianwei Xu Renke Kang Bi Zhang Yuan Zhang Chenxu Wang yan bao Zhigang dong State Key Laboratory of High-Performance Precision Manufacturing Dalian University of TechnologyDalian 116024People’s Republic of China Department of Mechanical and Energy Engineering Southern University of Science and TechnologyShenzhen 518055People’s Republic of China

Fatigue properties are crucial for critical aero-engine components in extreme serviceenvironments,which are significantly affected by surface integrity(SI)indexes(especially surface topography,residual stressσ_(res),and microhardness)after machining processes.Normal-direction ultrasonic vibration-assisted face grinding(ND-UVAFG)has advantages in improving the machinability of Inconel 718,but there is a competitive relationship between higher compressiveσ_(res)and higher surface roughness R_(a)in affecting fatigue strength.The lack of a quantitative relationship between multiple SI indexes and fatigue strength makes theindeterminacy of a regulatory strategy for improving fatigue properties.In this work,a model of fatigue strength(σ_f)_(sur)considering multiple SI indexes was developed.Then,high-cycle fatigue tests were carried out on Inconel 718 samples with different SI characteristics,and the influence of ND-UVAFG process parameters on SI was analyzed.Based on SI indexes data,the(σ_f)_(sur)distribution in the grinding surface layer for ND-UVAFG Inconel 718 samples was determined using the developed model,and then the fatigue crack initiation(FCI)sites were furtherpredicted.The predicted FCI sites corresponded well with the experimental results,therebyverifying this model.A strategy for improving the fatigue life was proposed in this work,which was to transfer the fatigue source from the machined surface to the bulk material by controlling the SI indexes.Finally,a critical condition of SI indexes that FCI sites appeared on the surface or in bulk material was given by fitting the predicted results.According to the critical condition,an SI field where FCI sites appeared in the bulk material could be obtained.In this field,thefatigue life of Inconel 718 samples could be improved by approximately 140%.

关键词： surface integrity fatigue strength Inconel 718 ultrasonic assisted grinding

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Laser-assisted grinding of RB-SiC composites:Laser ablation behavior and mechanism

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Chinese Journal of Aeronautics 2024年第1期37卷 362-376页

作者： Zhigang dong Wenchao SUN Xintong CAI Feng yanG yan bao Renke KANG dongjiang WU Guangyi MA Fangyong NIU Key Laboratory for Precision and Non-traditional Machining Technology of the Ministry of Education School of Mechanical EngineeringDalian University of TechnologyDalian 116024China

Laser ablation is an important process during Laser-Assisted Grinding(LAG)of hard and brittle materials.To realize controllable material removal during laser ablation of RB-SiC composites,ablation experiments under different Laser Energy Density(LAED)and LAG experiments are conducted.Evolution rules and mechanism of physical phase,ablation morphology and crack characteristics caused by laser irradiation are investigated.The forces of LAG and Conventional Grinding(CG)are compared.The results show that ablation surface changes from slight oxidation to obvious material removal with LAED increasing,and ablation depth increases gradually.The ablation products change from submicron SiO_(2)particles to nanoscale particles and floccule.High LAED promotes SiC decomposition and sublimation,which leads to the increase of C element.The SiC phase forms corrugated shape in recast layer and columnar shape in Heat Affected Zone(HAZ)at 56 J/mm^(2).The cold and heat cycle leads to formation of fishbone crack.For ablation specimen under 30 J/mm^(2),the grinding force can be reduced by a maximum of 39%and brittle damage region is reduced.The material removal and microcrack generated will significantly reduce the hardness and improve machinability,which can promote grinding efficiency.

关键词： RB-SiC Laser Ceramic Composites Grinding

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MFG-E8 Alleviates Cognitive Impairments Induced by Chronic Cerebral Hypoperfusion by Phagocytosing Myelin Debris and Promoting Remyelination

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Neuroscience Bulletin 2024年第4期40卷 483-499页

作者： Xiaohong dong Zhi Zhang Xin Shu Zi Zhuang Pinyi Liu Renyuan Liu Shengnan Xia Xinyu bao Yun Xu yan Chen Department of Neurology Nanjing Drum Tower HospitalAffiliated Hospital of Medical SchoolNanjing UniversityNanjing210008China Department of Neurology Nanjing Drum Tower Hospital Clinical College of Traditional Chinese and Western MedicineNanjing University of Chinese MedicineNanjing210008China Department of Neurology Drum Tower Hospital of Nanjing Medical UniversityNanjing210008China Jiangsu Key Laboratory for Molecular Medicine Medical School of Nanjing UniversityNanjing210008China Jiangsu Provincial Key Discipline of Neurology Nanjing210008China

Chronic cerebral hypoperfusion is one of the pathophysiological mechanisms contributing to cognitive decline by causing white matter injury.Microglia phagocytosing myelin debris in a timely manner can promote remyelination and contribute to the repair of white matter.However,milk fat globule-epidermal growth factor-factor 8(MFG-E8),a microglial phagocytosis-related protein,has not been well studied in hypoperfusion-related cognitive dysfunction.We found that the expression of MFG-E8 was significantly decreased in the brain of mice after bilateral carotid artery stenosis(BCAS).MFG-E8 knockout mice demonstrated more severe BCAS-induced cognitive impairments in the behavioral tests.In addition,we discovered that the deletion of MFG-E8 aggravated white matter damage and the destruction of myelin microstructure through fluorescent staining and electron microscopy.Meanwhile,MFG-E8 overexpression by AAV improved white matter injury and increased the number of mature oligodendrocytes after BCAS.Moreover,in vitro and in vivo experiments showed that MFG-E8 could enhance the phagocytic function of microglia via theαVβ3/αVβ5/Rac1 pathway and IGF-1 production to promote the differentiation of oligodendrocyte progenitor cells into mature oligodendrocytes.Interestingly,we found that MFG-E8 was mainly derived from astrocytes,not microglia.Our findings suggest that MFG-E8 is a potential therapeutic target for cognitive impairments following cerebral hypoperfusion.

关键词： White matter injury Cognitive dysfunction MFG-E8 Remyelination Microglial phagocytosis

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A 10-yr Rainfall and Cloud-to-Ground Lightning Climatology over Coastal and Inland Regions of Guangdong, China during the Pre-Summer Rainy Season

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Journal of Meteorological Research 2024年第3期38卷 469-488页

作者： Yuqing RUAN Rudi XIA Xinghua bao dong ZHENG yan SHEN Jinfang YIN State Key Laboratory of Severe Weather Chinese Academy of Meteorological SciencesChina Meteorological Administration Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters Nanjing University of Information Science & Technology National Meteorological Information Centre China Meteorological Administration

A comparative analysis of the spatiotemporal distribution characteristics of rainfall and lightning in coastal and inland areas of Guangdong Province of China during the pre-summer rainy season(PSRS) from 2008 to 2017 reveals distinct patterns. In the inland target region(ITR), rainfall is concentrated in the central and eastern mountainous areas. It exhibits a bimodal diurnal variation, with peaks in the afternoon and morning. The afternoon peak becomes more pronounced during the post-monsoon-onset period because of the increased rainfall frequency. Similarly, in the coastal target region(CTR), rainfall concentrates around mountainous peripheries. However, CTR's rainfall is weaker than ITR's during the pre-monsoon-onset period, primarily associated with the lower-level moisture outflow in CTR,but it strengthens significantly during the post-monsoon-onset period owing to enhanced moisture inflow. CTR's diurnal rainfall variation transitions from bimodal to a single broad peak during the post-monsoon-onset period, influenced by changes in both rainfall frequency and intensity. In contrast to rainfall, the spatiotemporal distribution of lightning centers remains relatively stable during the PSRS. The strongest center is located over ITR's plains west of the rainfall center, with a secondary center in the western plains of CTR. Lightning activity significantly increases during the post-monsoon-onset period, particularly in ITR, primarily because of the increased lightning hours. The diurnal lightning flash density and lightning hours show a single afternoon peak in the two target regions, and the timing of the peak in ITR is approximately two hours later than in CTR. Composite circulation analysis indicates that during early morning, the lower atmosphere is nearly neutral in stratification. The advected warm, moist, unstable airflow, combined with topography, favors convection initiation. In the afternoon, solar radiation increases thermal instability, further enhancing the convection frequency and intensity. Improv

关键词： rainfall lightning spatiotemporal distribution diurnal variation pre-summer rainy season

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A Modified Iterative Learning Control Approach for the Active Suppression of Rotor Vibration Induced by Coupled Unbalance and Misalignment

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Chinese Journal of Mechanical Engineering 2024年第1期37卷 242-253页

作者： Yifan bao Jianfei Yao Fabrizio Scarpa yan Li College of Mechanical and Electrical Engineering Beijing University of Chemical TechnologyBeijing 100029China State Key Laboratory of High-end Compressor and System Technology Beijing 100029China Beijing Key Laboratory of High-end Mechanical Equipment Health Monitoring and Self-Recovery Beijing University of Chemical TechnologyBeijing 100029China Key Lab of Engine Health Monitoring-Control and Networking of Ministry of Education Beijing University of Chemical TechnologyBeijing 100029China Bristol Composites Institute(ACCIS) University of BristolBristol BS81TRUK Dynamics and Control Research Group(DCRG) University of BristolBristol BS81TRUK

This paper proposes a modified iterative learning control(MILC)periodical feedback-feedforward algorithm to reduce the vibration of a rotor caused by coupled unbalance and parallel misalignment.The control of the vibration of the rotor is provided by an active magnetic actuator(AMA).The iterative gain of the MILC algorithm here presented has a self-adjustment based on the magnitude of the vibration.Notch filters are adopted to extract the synchronous(1×Ω)and twice rotational frequency(2×Ω)components of the rotor vibration.Both the notch frequency of the filter and the size of feedforward storage used during the experiment have a real-time adaptation to the rotational speed.The method proposed in this work can provide effective suppression of the vibration of the rotor in case of sudden changes or fluctuations of the rotor speed.Simulations and experiments using the MILC algorithm proposed here are carried out and give evidence to the feasibility and robustness of the technique proposed.

关键词： Rotor vibration suppression Modified iterative learning control Unbalance Parallel misalignment Active magnetic actuator

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Strong-coupling superconductivity with Tc above 70 K in Be-decorated monolayer T-graphene

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Science China(Physics,Mechanics & Astronomy) 2024年第1期67卷 99-105页

作者： Liu yang Peng-Fei Liu Hao-dong Liu Ya-Ping Li Na Jiao Hong-yan Lu bao-Tian Wang Ping Zhang School of Physics and Physical Engineering Qufu Normal UniversityQufu 273165China Institute of High Energy Physics Chinese Academy of SciencesBeijing 100049China Spallation Neutron Source Science Center Dongguan 523803China Institute of Applied Physics and Computational Mathematics Beijing 100088China

Using first-principles calculations,we predict a new type of two-dimensional(2D)beryllium(Be)-decorated T-graphene named BeC_(2),where Be atoms are inserted into C–C bonds linking the carbon tetrarings of T-graphene.The band structure shows that BeC_(2)is metallic,thus,the possible phonon-mediated superconductivity is explored based on the Eliashberg equation.The calculated electron-phonon coupling(EPC)constantλis up to 4.07,and the corresponding superconducting critical temperature(Tc)is 72.1 K,approaching the liquid nitrogen temperature.The reason for the high Tc is the strong EPC.And it is proved to be an anisotropic single-gap superconductor by analyzing the superconducting gap?kof BeC_(2).The electronic susceptibility calculation shows strong nesting effect in BeC_(2).Since rare 2D superconductors show such a strong EPC constantλwhich originates from the coupling between electrons in C-pzorbital and in-plane vibrations of Be and C atoms,the predicted BeC_(2)provides a new platform for investigating strong EPC 2D superconductor.

关键词： two-dimensional carbon-based superconductor electron-phonon coupling strong coupling high superconducting critical temperature

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Module Structures on U(ε^(-))for the Euclidean Algebra

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Algebra Colloquium 2024年第1期31卷 49-56页

作者： Yixin bao yan'an Cai School of Sciences Harbin Institute of Technology ShenzhenGuangdong 518055China Department of Mathematics Soochow University SuzhouJiangsu 215006China

We classify modules which are free of rank 1 when restricted to the negative part for the Euclidean Lie algebra.Sufficient and necessary conditions for the simplicity of these modules are given.From these modules we c... 详细信息

关键词： Euclidean algebra free module simple module nonweight module

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Safety and efficacy of a programmed cell death 1 inhibitor combined with oxaliplatin plus S-1 in patients with Borrmann large type III and IV gastric cancers

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World Journal of Gastrointestinal Oncology 2024年第4期16卷 1281-1295页

作者： Zhe-Han bao Can Hu yan-Qiang Zhang Peng-Cheng Yu Yi Wang Zhi-Yuan Xu Huan-Ying Fu Xiang-dong Cheng Department of Interventional Radiology Zhejiang Cancer HospitalHangzhou 310004Zhejiang ProvinceChina Department of Gastric Surgery Zhejiang Cancer HospitalHangzhou 310022Zhejiang ProvinceChina Department of Colonic Surgery Jinhua Central HospitalJinhua 321000Zhejiang ProvinceChina Department of Breast Surgery Lin’an People’s HospitalHangzhou 311300Zhejiang ProvinceChina

BACKGROUND Gastric cancer(GC)is the fifth most common and the fourth most lethal malignant tumour in the world.Most patients are already in the advanced stage when they are diagnosed,which also leads to poor overall survival.The effect of posto-perative adjuvant chemotherapy for advanced GC is unsatisfactory with a high rate of distant metastasis and local recurrence.AIM To investigate the safety and efficacy of a programmed cell death 1(PD-1)inhibitor combined with oxaliplatin and S-1(SOX)in the treatment of Borrmann large type III and IV GCs.METHODS A retrospective analysis(IRB-2022-371)was performed on 89 patients with Borrmann large type III and IV GCs who received neoadjuvant therapy(NAT)from January 2020 to December 2021.According to the different neoadjuvant treatment regimens,the patients were divided into the SOX group(61 patients)and the PD-1+SOX(P-SOX)group(28 patients).RESULTS The pathological response(tumor regression grade 0/1)in the P-SOX group was significantly higher than that in the SOX group(42.86%vs 18.03%,P=0.013).The incidence of ypN0 in the P-SOX group was higher than that in the SOX group(39.29%vs 19.67%,P=0.05).The use of PD-1 inhibitors was an independent factor affecting tumor regression grade.Meanwhile,the use of PD-1 did not increase postoperative complications or the adverse effects of NAT.CONCLUSION A PD-1 inhibitor combined with SOX could significantly improve the rate of tumour regression during NAT for patients with Borrmann large type III and IV GCs.

关键词： Neoadjuvant therapy Immunotherapy Gastric cancer Borrmann type Tumor regression grade

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Electromagnetic characteristic analysis and design of a linear motor used for ultra-high-speed EMS maglev train

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Science China(Technological Sciences) 2024年第6期67卷 1957-1973页

作者： GAO Han SHI TingNa GAO XinMai LEI yanXiao yan dong GUO Liyan yan yan College of Electrical Engineering Zhejiang UniversityHangzhou310027China Zhejiang University Advanced Electrical Equipment Innovation Center Hangzhou311107China State Key Laboratory of High-speed Maglev Transportation Technology Qingdao266100China CRRC Qingdao Sifang Co.Ltd. Qingdao266111China

The operating speed of the commercial electromagnetic suspension(EMS)maglev train has been over 430 km/h,making it the fastest means of land transportation.With the increasing demands of people traveling,it is necessary to further improve the operating speed of maglev trains.Aiming to examine whether the existing EMS system can meet the requirements of ultra-highspeed operation(more than 600 km/h),the electromagnetic characteristics of an EMS linear motor under the operating speed of 600–1000 km/h fed by a square-wave voltage supply is investigated in this article.First,an electromagnetic field model of the EMS system under the square-wave voltage supply is established to investigate its electromagnetic performance,e.g.,the characteristics of phase current,the magnetic flux density,and the electromagnetic force.Second,the relationship between the harmonic components of the air-gap magnetic flux density and electromagnetic force is investigated using the two-dimensional fast Fourier transform(2D-FFT)to reveal the mechanism of electromagnetic force ripple.Third,to address the issues of excessive armature current density and significant electromagnetic force ripple,the linear motor is re-designed by enlarging the stator slot area and reshaping the mover's main magnetic poles.Furthermore,the Taguchi method is used to further improve the electromagnetic characteristics of the linear electric motor.Finally,the effectiveness of the proposed optimal design is validated by the finite-element analysis(FEA)based co-simulation.

关键词： ultra-high-speed maglev transportation electromagnetic suspension(EMS) linear motor electromagnetic force ripple suppression

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