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Material flow behavior and microstructural evolution during refill friction stir spot welding of alclad 2A12-T4 aluminum alloy

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International Journal of Minerals,Metallurgy and Materials 2021年第1期28卷 131-141页

作者： Gao-hui Li Li Zhou Ling-yun Luo xi-ming wu Ning Guo State Key Laboratory of Advanced Welding and Joining Harbin Institute of TechnologyHarbin 150001China Shandong Provincial Key Laboratory of Special Welding Technology Harbin Institute of Technology(WeihaiWeihai)264209China

In this study, we used the stop-action technique to experimentally investigate the material flow and microstructural evolution of alclad 2A12-T4 aluminum alloy during refill friction stir spot *** are two material flow components, i.e., the inward-or outward-directed spiral flow on the horizontal plane and the upward-or downward-directed flow on the vertical *** the plunge stage, the flow of plasticized metal into the cavity is similar to that of a stack, whereby the upper layer is pushed upward by the lower *** the refill stage, this is process *** such, there is no obvious vertical plasticized metal flow between adjacent *** leads to the coarsening of S(Al2CuMg) in the thermo-mechanically affected zone and the diminishing of S in the stir *** dynamic recrystallization results in the formation of fine equiaxed grains in the stir zone, but this process becomes difficult in the thermo-mechanically affected zone due to the lower deformation rate and the pinning action of S precipitates on the dislocations and sub-grain boundaries, which leads to a high fraction of low-angle grain boundaries in this zone.

关键词： refill friction stir spot welding aluminum alloy material flow behavior precipitate evolution dislocation configuration

Transactive Energy Trading in Reconfigurable Multi-carrier Energy Systems

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Journal of Modern Power Systems and Clean Energy 2020年第1期8卷 67-76页

作者： Yifei Wang Zhiheng Huang Zhenhao Li xi wu Loi Lei Lai Fangyuan Xu School of Automation Guangdong University of TechnologyGuangzhouChina School of Electrical Engineering Southeast UniversityNanjingChina

The penetration of multi-carrier energy systems in distribution system gains more and more *** this paper,a bi-level transactive energy trading framework is proposed to improve the energy scheduling and operation efficiency for multi-carrier energy systems which are modeled as energy hubs(EHs).In the upper level,each EH in the distribution system not only makes energy scheduling decisions considering supplies and demands of local energy,but also trades energy with each other to further maximize their social *** associated trading payment among EHs is made in a fair manner by applying Nash bargaining *** solve the bargaining problem by decomposing it into two subproblems:operation cost minimization problem and payment bargaining ***,based on the trading decision,the nodal equivalent loads of EHs are sent to the distribution system operator(DSO)without publishing trading *** applying the second-order cone programming(SOCP),DSO reconfigures the network to reduce the transmission loss of the system in the lower *** network reconfiguration and the trading behavior of EHs interact and iterate until the *** studies on modified IEEE 33-bus distribution system demonstrate the effectiveness of the proposed framework.

关键词： Multi-carrier energy system energy hub(EH) transactive energy distribution reconfiguration Nash bargaining

Experimental investigation on using CO_(2)/H_(2)O emulsion with high water cut in enhanced oil recovery

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Petroleum Science 2024年第2期21卷 974-986页

作者： xi-Dao wu Peng xiao Bei Liu Guang-Jin Chen Jian-Hua Pang State Key Laboratory of Heavy Oil Processing China University of PetroleumBeijing102249China Ocean Intelligence Technology Center Shenzhen Institute of Guangdong Ocean UniversityShenzhen518120GuangdongChina

CO_(2) emulsions used for EOR have received a lot of interest because of its good performance on CO_(2)mobility ***,most of them have been focusing on the high quality CO_(2) emulsion(high CO_(2) fraction),while CO_(2) emulsion with high water cut has been rarely *** this paper,we carried out a comprehensive experimental study of using high water cut CO_(2)/H_(2)O emulsion for enhancing oil ***,a nonionic surfactant,alkyl glycosides(APG),was selected to stabilize CO_(2)/H_(2)O emulsion,and the corresponding morphology and stability were evaluated with a transparent PVT ***,plugging capacity and apparent viscosity of CO_(2)/H_(2)O emulsion were measured systematically by a sand pack displacement apparatus connected with a 1.95-m long capillary ***,a high water cut(40 vol%) CO_(2)/H_(2)O emulsion was selected for flooding experiments in a long sand pack and a core sample,and the oil recovery,the rate of oil recovery,and the pressure gradients were *** results indicated that APG had a good performance on emulsifying and stabilizing CO_(2) *** inversion from H_(2)O/CO_(2) emulsion to CO_(2)/H_(2)O emulsion with the increase in water cut was ***_(2)/H_(2)O emulsions with lower water cuts presented higher apparent viscosity,while the optimal plugging capacity of CO_(2)/H_(2)O emulsion occurred at a certain water ***,the displacement using CO_(2)/H_(2)O emulsion provided 18.98% and 13.36% additional oil recovery than that using pure CO_(2) in long sand pack and core tests,*** work may provide guidelines for EOR using CO_(2) emulsions with high water cut.

关键词： CO_(2)/H_(2)O emulsion High water cut CO_(2) mobility control Enhanced oil recovery

Partial purification of Cytochrome P450 from Helicoverpa armigera （Hübner）

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Insect Science 2005年第4期12卷 313-317页

作者： CAI-HONG YU xi-wu GAO Department of Entomology China Agricultural University Beijing China College of Chemistry and Environment Engineering China University of Mining and Technology BeijingChina.

The cytochrome P450 （Cyt-P450） proteins from the fat body and midgut of the cotton bollworm, Helicoverpa armigera, were respectively partially purified by a set of purification procedures including differential centrifugation, solubilization of CHAPS, protein precipitation by PEG precipitation and DE-32 column chromatography. The CytP450 was detected by methods of CO difference spectrum and SDS-PAGE. Fraction of detergent solubilized microsomes from the fat body of H. armigera was purified more than 17-fold. Three protein bands were detected by SDS-PAGE with molecular masses of 70 600, 63 300 and 571 200Da. It is possible that the proteins with molecular mass of 63 300 and 571 200Da were the isozymes of Cyt-P450.

关键词： Helicoverpa armigera (Hiabner) cytochrome P450 purification protein midgut fat body

Study of Sallen–Key digital filters in nuclear pulse signal processing

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Nuclear Science and Techniques 2019年第10期30卷 1-8页

作者： Huai-Qiang Zhang Bin Tang He-xi wu Zhuo-Dai Li Fundamental Science on Radioactive Geology and Exploration Technology Laboratory East China University of TechnologyNanchang 330013China School of Nuclear Science and Engineering East China University of TechnologyNanchang 330013China

The Sallen–Key filter(S–K)is widely used in nuclear pulse signal processing because of its simple working principle and good *** research has only reviewed the recursive numerical model of digital S–K using idealized *** use of digital S–K thus has limitations under these *** paper comprehensively deduces a recursive numerical model of digital S–K and discusses the effects of resistance and capacitance on the filter quality factor,cutoff frequency and amplitude–frequency *** numerical recursive function,transfer function and amplitude–frequency response are analyzed using different *** a comparative analysis of the shaper in a simulation and an actual nuclear signal,an optimal parameter selection principle is *** different forming parameters,the energy resolution and pulse counting rate of the 55Fe energy spectrum are compared and analyzed based on a Si-PIN *** has a stronger influence on the Gaussian shape,whereas the influence of resistance is stronger on the shaping amplitude.

关键词： Digital Sallen–Key Amplitude–frequency response Gaussian shaping Energy resolution

Effects of methamidophos and deltamethrin on in vitro protein phosphorylation in Monochamus alternatus

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Insect Science 2008年第6期15卷 529-535页

作者： Jie Liu xi-wu Gao Yi-Jun wu Wei Li Qi-Lian Qin Jiang-Hua Sun State Key Laboratory of Integrated Management of Pest Insects and Rodents Institute of Zoology Chinese Academy of Sciences Beijing College of Agronomy and Biotechnology China Agricultural University Beijing China

Monochamus alternatus Hope （Coleoptera： Cerambycidae） is not only a serious pest insect to pine trees but also the main vector of pine wood nemadote Bursaphelenchus xylophilus, which causes pine wilt disease. To explore the insecticidal mechanism of insecticides to M. alternatus, we chose methamidophos and deltamethrin as the representatives of two groups of insecticides （organophosphates and pyrethroids）, which are widely used for pest control in China and investigated their effects on phosphorylation of proteins from the insect. Phosphorylation of proteins from the insect fat body and head was determined by in vitro 32P-labelling. In the fat body, deltamethrin obviously reduced basal phosphorylation levels of proteins at 111, 95, 77, and 44 kDa, but enhanced the basal phosphorylation level of a protein at 138 kDa. However, in the presence of calmodulin but not cyclic adenosine monophosphate （cAMP）, deltamethrin increased phosphorylation of the protein at 111 kDa. In the head, deltamethrin inhibited basal phosphorylation levels of proteins at 113, 98, and 51 kDa, but potentiated phosphorylation of a protein at 167 kDa activated by cAMP. Methamidophos inhibited phosphorylation of a protein at 44 kDa in the fat body. Although methamidophos did not impact basal phosphorylation levels of any proteins in the head, it inhibited calcium/calmodulin （Ca^2＋CaM）-stimulated phosphorylation of a protein at 51 kDa. Together, our data indicate that methamidophos and deltamethrin altered phosphorylation levels of various proteins in the head and fat body of the pine insect and these two kinds of insecticides acted on the proteins that can be phosphorylated in the tissues respectively, which is possibly related to their toxicity.

关键词： methamidophos deltamethrin Monochamus alternatus protein phosphorylation

Propagation of Localized Excitations in Desoxyribonucleic Acid

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Chinese Physics Letters 1997年第12期14卷 957-960页

作者： YANG xian-jun ZHUO Yi-zhong wu xi-zhen China Institute of Atomic Energy Beijing 102413 Department of Physics Guizhori Institute for NationalitiesGuiyang 550025 Institute of Theoretical Physics Chinese Academy of SciencesBeijing 100080

The result that the process by which the pulses,initially distributed in desoxyribonucleic acid(DNA)molecules can resume its form to localize the large amplitude excitations is *** process may play an important role i... 详细信息

关键词： bubble initially excitation

The puzzling association between inventory and auditor pricing in China

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China Journal of Accounting Research 2018年第4期11卷 351-366页

作者： xi wu Xueqin Wang Yulong Yang School of Accountancy Central University of Finance and Economics China's Management Accounting Research & Development Center Central University of Finance and Economics College of Management and Economics Tianjin University

The theory of audit pricing suggests that audit fees are positively associated with areas of higher inherent risk. Inventory is commonly cited as one such area, and many Western studies have reported a positive association between inventory and audit fees. However, most Chinese studies have reported a significant negative association. This study finds that this puzzling association is attributable to Chinese auditors charging a significant discount on the opening balance of inventory, whereas their U.S. counterparts charge a significant premium. Meanwhile, we show that opening-balance inventory is associated with higher inherent risk both in China and the U.S. On the other hand, both Chinese and U.S. auditors charge a significant discount on the net increase in inventory as of the current year end, and we show that this is associated with lower inherent risk. Therefore, Chinese auditors appear to underreact to the inherent risk associated with opening-balance inventory, which helps explain the puzzling negative association between inventory and audit fees in China.

关键词： Inventory Audit fees Inherent risk China

Tuning the reactivity of Al-Ni by fine coating of halogen-containing energetic composites

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Defence Technology（防务技术） 2022年第10期18卷 1810-1821页

作者： Su-lan Yang Ke-juan Meng wu-xi xie Hong-qi Nie Qi-Long Yan Science and Technology on Combustion Internal Flow and Thermo-Structure LaboratoryNorthwestern Polytechnical UniversityXi'an710072China b xi'an Modern Chemistry Research Institute Xi'an710065China

In this paper,various core-shell structured Al—Ni@ECs composites have been prepared by a spray-drying *** involved ECs refer to the energetic composites(ECs)of ammonium perchlorate/nitrocellulose(AP/NC,NA)and polyvinylidene fluoride/hexanitrohexaazaisowurtzitane(PVDF/CL-20,PC).Two Al—Ni mixtures were prepared at atomic ratios of 1:1 and 1:3 and named as Al/Ni and Al/3Ni,*** thermal reactivity and combustion behaviors of Al—Ni@ECs composites have been comprehensively *** showed that the reactivity and combustion performance of Al—Ni could be enhanced by introducing both NA and PC energetic *** which the Al/Ni@NA composite exhibited higher reactivity and improved combustion *** measured flame propagation rate(v=20.6 mm/s),average combustion wave temperature(T_(max)=1567.0°C)and maximum temperature rise rate(γ_(t)=1633.6°C/s)of Al/Ni@NA are higher than that of the Al/Ni(v=15.8 mm/s,T_(max)=858.0°C,andγ_(t)=143.5°C/s).The enhancement in combustion properties could be due to presence of the acidic gaseous products from ECs,which could etch the Al_(2)O_(3)shell on the surface of Al particles,and make the inner active Al to be easier transported,so that an intimate and faster intermetallic reaction between Al and Ni would be ***,the morphologies and chemical compositions of the condensed combustion products(CCPs)of Al—Ni@ECs composites were found to be different depending on the types of *** compositions of CCPs are dominated with the Al—Ni intermetallics,combining with a trace amount of Al_(5)O_(6)N and Al_(2)O_(3).

关键词： Arrested high energy ball milling Intermetallic alloy Combustion performance Energetic composites Reactivity control