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Axial-torsional nonlinear vibration of bottom hole assembly in the air drilling technology

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Petroleum 2024年第3期10卷 446-461页

作者： Shujie Ding Pan Fang gao Li Junan Lu Yanmin Wang Yang Li Yutian Han dong xiao School of Mechanical Engineering Southwest Petroleum UniversityChengdu610500China Petroleum Engineering School Southwest Petroleum UniversityChengdu610500China Petrochina Tarim Oilfield CNPCKorla841000China PetroChina Huabei Oilfield Co CNPC834000China

The safety and efficiency of drilling engineering are greatly impeded by destructive vibrations of drill string in air drilling,such as stick-slip,bit-bounce and their coupled *** avoid or suppress these vibrations improving the stability of drilling operations,revealing the occurrence mechanisms of abovementioned harmful vibrations are indispensable by investigating dynamics characteristics of drill string *** this paper,an axial-torsional coupled dynamics model that can capture the motion behaviors of bottom hole assembly(BHA)is established adopting the lumped parameter ***,a rate of penetration(ROP)model appropriating for air drilling is obtained firstly by linear fitting ***,a novel discontinuous support model is established to describe the bitformation ***,BHA dynamics are discussed using numerical simulations under different vibration scenarios:normal operation;stick-slip;bit-bounce;bit-bounce and stick-slip ***,in two drilling modes:the continuous and intermittent drilling,the vibration mitigation strategies and dynamics sensibility study of BHA are carried out based on the parametric *** results show that increasing torsional stiffness of drill-pipes,appropriately adjusting rotation speed of top driven system and dynamic weight on bit(WOB)are deemed as an effective strategy suppressing or eliminating stick-slip and bit-bounce vibrations of *** that the rotation speed of top driven system and dynamic WOB are 5 rad/s and 3.5 kN,***,the constructed probability maps allow to driller to choose reasonable mechanical parameters,thereby realizing smooth drilling operation in the air drilling.

关键词： Drill string BHA Contact model ROP Stick-slip Bit-bounce

Visible-light-activated aziridination reaction enables simultaneous resolving of C=C bond location and the sn-position isomers in lipids

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Chinese Chemical Letters 2024年第4期35卷 481-485页

作者： Qiongqiong Wan Yanan xiao Guifang Feng Xin dong Wenjing Nie Ming gao Qingtao Meng Suming Chen The Institute for Advanced Studies Renmin Hospital of Wuhan UniversityWuhan UniversityWuhan 430072China

There is a close relationship between the biological functions of lipids and their structures, and various isomers greatly increases the complexity of lipid structures. The C=C bond location and sn-position are two of the essential attributes that determine the structures of unsaturated lipids. However, simultaneous identification of both attributes remains challenging. Here, we develop a visible-light-activated aziridination reaction system, which enables the dual-resolving of the C=C bond location and sn-position isomerism of in lipids when combines with liquid chromatography-mass spectrometry(LC-MS). Based on the derivatization of C=C bonds with Ph I=NTs, their location in lipids could be easily identified by tandem MS. Especially, the sn-position isomers of unsaturated phosphatidylcholine(PC) can be separated and quantified by LC-MS after the derivatization. By using the proposed method, the significant changes of the sn-position isomers ratios of PC in mouse brain ischemia were revealed. This study offers a powerful tool for deep lipid structural biology.

关键词： Aziridination Lipid isomers C=C bond location sn-Position Mass spectrometry

Distributed Source-Load-Storage Cooperative Low-Carbon Scheduling Strategy Considering Vehicle-to-Grid Aggregators

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Journal of Modern Power Systems and Clean Energy 2024年第2期12卷 440-453页

作者： xiao Xu Ziwen Qiu Teng Zhang Hui gao School of Automation Nanjing University of Posts and TelecommunicationsNanjing210023China

The vehicle-to-grid(V2G)technology enables the bidirectional power flow between electric vehicle(EV)batteries and the power grid,making EV-based mobile energy storage an appealing supplement to stationary energy storage ***,the stochastic and volatile charging behaviors pose a challenge for EV fleets to engage directly in multi-agent *** unlock the scheduling potential of EVs,this paper proposes a source-load-storage cooperative low-carbon scheduling strategy considering V2G *** uncertainty of EV charging patterns is managed through a rolling-horizon control framework,where the scheduling and control horizons are adaptively adjusted according to the availability periods of ***,a Minkowski-sum based aggregation method is employed to evaluate the scheduling potential of aggregated EV fleets within a given scheduling *** method effectively reduces the variable dimension while preserving the charging and discharging constraints of individual ***,a Nash bargaining based cooperative scheduling model involving a distribution system operator(DSO),an EV aggregator(EVA),and a load aggregator(LA)is established to maximize the social welfare and improve the low-carbon performance of the *** model is solved by the alternating direction method of multipliers(ADMM)algorithm in a distributed manner,with privacy of participants fully *** proposed strategy is proven to achieve the objective of low-carbon economic operation.

关键词： Electric vehicle(EV) low-carbon scheduling mobile storage system Nash bargaining power flexibility alternating direction method of multipliers(ADMM).

Distortion-aware beamforming design for multi-beam satellite communications with nonlinear power amplifiers

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Science China(Information Sciences) 2024年第6期67卷 359-369页

作者： Xiang xiao Li YOU Kezhi WANG Xiqi gao National Mobile Communications Research Laboratory Southeast University Purple Mountain Laboratories Department of Computer Science Brunel University London

Hardware components can cause different impairments, including power amplifier(PA) nonlinearities, which inevitably impact the system performance of satellite communications(SATCOM). In this work, we consider a multi-beam SATCOM downlink system and investigate the distortion-aware beamforming scheme with the characteristics of PA non-linearities. Notably, we aim to maximize the resource efficiency(RE), defined as the weighted sum of energy efficiency(EE) with spectral efficiency(SE), to obtain a flexible EE-SE tradeoff while accounting for the characteristics of PA distortion and the total power *** that the optimization objective is a sum of ratios and the high non-convexity involved in constraints,we propose an efficient approach that exploits the quadratic transformation, the Lagrange multiplier method,and the gradient ascent approach to handle this issue. Simulation results demonstrate the effectiveness of the distortion-aware beamforming approach in achieving the EE-SE tradeoff and exhibit a substantial RE performance gain over the conventional approach with ideal linear PAs assumed at the satellite transmitters.

关键词： multi-beam satellite communications nonlinear power amplifier energy and spectral efficiency tradeoff resource efficiency robust beamforming

Effect of oxide inclusions on MnS precipitates and tensile mechanical property of high-strength low-alloy steel

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Journal of Iron and Steel Research International 2024年第5期31卷 1210-1220页

作者： xiao-yong gao Hong Wei Li-feng Zhang School of Mechanical Engineering Yanshan UniversityQinhuangdao066004HebeiChina School of Materials Science and Engineering Yanshan UniversityQinhuangdao066004HebeiChina School of Mechanical and Materials Engineering North China University of TechnologyBeijing100144China

The key role of oxide inclusions on the microstructure and mechanical property of a high-strength low-alloy steel was *** field emission scanning electron microscope equipped with energy-dispersive spectrometry was used to characterize MnS *** inclusions play an important role in the shape control of MnS *** oxides fovored to decrease the size and the aspect ratio of MnS *** less oxide inclusions in the steel,approximately over 16.7%MnS precipitates were with aspect ratio a>5 and pure MnS precipitates accounted for 75.9%in ***,with more oxide inclusions in the steel,only 7.4%MnS precipitates were with a>5 and pure MnS precipitates accounted for 60.1%in *** of MnS by oxide inclusions improved the strength and inhibited the *** oxide inclusions in the steel increased the yield strength and tensile strength of the steel in both longitudinal and transverse directions,and lowered the anisotropy of the mechanical property.

关键词： High-strength low-alloy steel MnS Oxide inclusion Mechanical property Anisotropy

Covalency competition induced selective bond breakage and surface reconstruction in manganese cobaltite towards enhanced electrochemical charge storage

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Green Energy & Environment 2024年第5期9卷 909-918页

作者： Peng gao Pei Tang Ying Mo Peitao xiao Wang Zhou Shi Chen Hongliang dong Ziwei Li Chaohe Xu Jilei Liu College of Materials Science and Engineering Hunan Joint International Laboratory of Advanced Materials and Technology for Clean EnergyHunan Province Key Laboratory for Advanced Carbon Materials and Applied TechnologyHunan UniversityChangshaHunan410082China Department of Materials Science and Engineering National University of Defense TechnologyChangshaHunan410073China Joint Key Laboratory of the Ministry of Education Institute of Applied Physics and Materials EngineeringUniversity of MacaoAvenida da UniversidadeTaipaMacao999078China Center for High Pressure Science and Technology Advanced Research PudongShanghai201203China College of Aerospace Engineering Chongqing UniversityChongqing400044China

Manganese cobaltite(MnCo_(2)_(4))is a promising electrode material because of its attractive redox chemistry and excellent charge storage *** previous work demonstrated that the octahedrally-coordinated Mn are prone to react with the hydroxyl ions in alkaline electrolyte upon electrochemical cycling and separates on the surface of spinel to reconstruct into d-MnO_(2) nanosheets irreversibly,thus results in a change of the reaction mechanism with Kþion ***,the low capacity has greatly limited its practical ***,we found that the tetrahedrally-coordinated Co_(2) þions were leached when MnCo_(2)_(4) was equilibrated in 1 mol L^(-1) HCl solution,leading to the formation of layered CoOOH on MnCo_(2)_(4) surface which is originated from the covalency competition induced selective breakage of the CoT–O bond in CoT–O–CoO and subsequent rearrangement of free Co_(6) *** as-formed CoOOH is stable upon cycling in alkaline electrolyte,exhibits conversion reaction mechanism with facile proton diffusion and is free of massive structural evolution,thus enables utilization of the bulk electrode material and realizes enhanced speciﬁc capacity as well as facilitated charge transfer and ion *** general,our work not only offers a feasible approach to deliberate modiﬁcation of MnCo_(2)_(4)'s surface structure,but also provides an in-depth understanding of its charge storage mechanism,which enables rational design of the spinel oxides with promising charge storage properties.

关键词： Manganese cobaltite Tetrahedrally-coordinated Co^(2+)leaching Selective bond breakage Surface reconstruction Charge storage mechanisms

Intra-abdominal inflammatory myofibroblastic tumor:Spontaneous regression

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World Journal of Gastroenterology 2014年第37期20卷 13625-13631页

作者： Jun-Jie Zhao Jia-Qian Ling Yong Fang xiao-dong gao Ping Shu Kun-Tang Shen Jing Qin Yi-Hong Sun Xin-Yu Qin Department of General Surgery Zhong Shan HospitalFudan University

Inflammatory myofibroblastic tumors are usually treated by surgical resection. We herein report two cases of intra-abdominal inflammatory myofibroblastic tumors that were unresectable and underwent spontaneous regression without any treatment. Our case report and literature review show that regression is more common in the middle-aged and older male populations. Abdominal discomfort and fever were the most common symptoms, but the majority of patients had no obvious physical signs. There was no specific indicator for diagnosis. The majority of the lesions regressed within3 mo and nearly all of the masses completely resolved within 1 year. We conclude that the clinical characteristics of inflammatory myofibroblastic tumors are variable and, accordingly, the disease needs to be subdivided and treated on an individual basis. Surgery is always the first-line treatment; however, for those masses assessed as unresectable, conservative therapy with in-tense follow-up should be considered.

关键词： Inflammatory myofibroblastic tumor Inflammatory pseudotumor Abdominal cavity Spontaneous regression

On hypersurfaces of H2×H2

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Science China Mathematics 2024年第2期67卷 339-366页

作者： dong gao Hui Ma Zeke Yao School of Science Beijing University of Civil Engineering and Architecture Department of Mathematical Sciences Tsinghua University

In this paper, we study hypersurfaces of H2× H2. We first classify the hypersurfaces with constant principal curvatures and constant product angle functions. Then we classify homogeneous hypersurfaces and isoparametric hypersurfaces, respectively. Finally, we classify the hypersurfaces with at most two distinct constant principal curvatures, as well as those with three distinct constant principal curvatures under some additional conditions.

关键词： constant principal curvature homogeneous hypersurface isoparametric hypersurface 53C42 53B25 53C40

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 *** the increasing demands of people traveling,it is necessary to further improve the operating speed of maglev *** 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 ***,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 ***,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 ***,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 ***,the Taguchi method is used to further improve the electromagnetic characteristics of the linear electric ***,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