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Uniform decomposition of velocity gra.ient tensor

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Journa. of Hydrodyna.ics 2024年第1期36卷 24-34页

作者： Chenxi ma Cha.qun Liu Depa.tment of mathematics University of Texas at ArlingtonArlingtonTXUSA

In this pa.er,the principa. decomposition of the velocity gra.ient tensor[∇v]is discussed in 3 ca.es ba.ed on the discrimina.t∆:∆0 with 3 distinct rea. eigen va.ues,a.d∆=0 with 1 or 2 distinct rea. eigen *** velocity ... 详细信息

In this pa.er,the principa. decomposition of the velocity gra.ient tensor[∇v]is discussed in 3 ca.es ba.ed on the discrimina.t∆:∆a. eigen va.ue a.d a.pa.r of conjuga.e complex eigen va.ues,∆>0 with 3 distinct rea. eigen va.ues,a.d∆=0 with 1 or 2 distinct rea. eigen *** velocity gra.ient tensor ca. a.so be cla.sified a. rota.ion point,which ca. be decomposed into three pa.ts,i.e.,rota.ion[R],shea.[S]a.d stretching/compression[SC],a.d non-rota.ion point,we defined a.new resista.ce term[L],a.d the tensor ca. be decomposed into three pa.ts,i.e.,resista.ce[L],shea.[S]a.d stretching/compression[SC].Exa.ple matric a.e a.so displa.ed to demonstra.e the new *** of principa. decomposition between 3 different ca.es,a.d between Resista.ce a.d Liutex will a.so be discussed.

关键词： Velocity gra.ient Liutex resista.ce fluid kinematics

VOC emitted by biopha.maceutica. industries:Source profiles,hea.th risks,a.d seconda.y pollution

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Journa. of Environmenta. Sciences 2024年第1期135卷 570-584页

作者： Jia.ei ma Lin Li Sta.e Key La.ora.ory of Environmenta. a.ua.ic Chemistry Research Center for Eco-Environmental SciencesChinese Academy of SciencesBeijing 100085China University of Chinese a.a.emy of Sciences Beijing 100049China Na.iona. Engineering La.ora.ory for VOCs Pollution Control materia.&Technology University of Chinese Academy of SciencesBeijing 101408China

The biopha.maceutica. industry contributes substa.tia.ly to vola.ile orga.ic compounds(VOCs)emissions,ca.sing growing concerns a.d socia. developmenta. *** study conducted a. on-site investiga.ion of the process-ba.ed emission of VOCs from three biopha.maceutica. *** the workshops of the three enterprises,26 VOCs were detected,which could be sorted into 4 cla.ses:hydroca.bons,a.omatic hydroca.bons,oxygen-conta.ning compounds,a.d nitrogen-conta.ning *** were the main components of wa.te ga.es,a.counting for 44.13%-77.85%of the overa.l ***-ba.ed source profiles were compiled for ea.h process unit,with the fermenta.ion a.d extra.tion units of tia.ulin fumara.e being the main source of VOC *** hepta.one,vinyl a.eta.e,diethyla.ine,propylene glycol methyl ether(PGME),a.d benzene were screened a. priority polluta.ts through a.fuzzy comprehensive eva.ua.ion *** level concentra.ion simula.ion results of the Ga.ss plume diffusion model demonstra.ed tha. the diffusivity of VOCs in the a.mosphere wa. rela.ively high,indica.ing potentia. non-ca.cinogenic a.d ca.cinogenic risks 1.5-2 km ***,the process-ba.ed formation potentia.s of ozone a.d seconda.y orga.ic a.rosols(SOa.)were determined a.d indica.ed tha. N-methyl-2-pyrrolidone,dimethyl hepta.one,a.d PGME should be preferentia.ly controlled to reduce the ozone formation potentia.,wherea. the control of benzene a.d chlorobenzene should be prioritized to reduce the genera.ion of *** results provide a.ba.is for understa.ding the cha.a.teristics of VOC emission by biopha.maceutica. industries a.d their diffusion,potentia.ly a.lowing the development of mea.ures to reduce hea.th risks a.d seconda.y pollution.

关键词： Biopha.maceutica. Vola.ile orga.ic compound Priority polluta.t Exposure risk Seconda.y pollution

Deterministic a.d Robust Volt-va. Control Methods of Power System Ba.ed on Convex Deep Lea.ning

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Journa. of Modern Power Systems a.d Clea. Energy 2024年第3期12卷 719-729页

作者： Qing ma Cha.ghong Deng the School of Electrica. Engineering a.d a.tomation Wuhan UniversityWuhanChina

Volt-va. control(VVC)is essentia.ly a.non-convex optimiza.ion problem due to the non-convexity of power flow(PF)constra.nts,resulting in the difficulty in obta.ning the optimum without convexity *** existing second-order cone method for the convexity conversion often lea.s to a.sha.p increa.e in PF constra.nts a.d optimiza.ion va.ia.les,which in turn increa.es the optimiza.ion difficulty or even lea.s to optimiza.ion *** pa.er first proposes a.deterministic VVC method ba.ed on convex deep lea.ning power flow(DLPF).This method uses the input convex neura. network(ICNN)to esta.lish a.single convex mapping between sta.e pa.a.eters a.d node volta.e to complete the convexity conversion while the optimiza.ion va.ia.les only correspond to rea.tive power equipment,which ca. ensure the globa. optimum with extremely fa.t computa.ion *** cope with the impa.t brought by the uncerta.nty of distributed energy a.d omit the a.ditiona. worst scena.io sea.ch of tra.itiona. robust VVC,this pa.er proposes robust VVC method ba.ed on convex deep lea.ning interva. power flow(DLIPF),which continues to a.opt ICNN to esta.lish a.other convex mapping between sta.e pa.a.eters a.d node volta.e *** DLIPF with DLPF,this method decrea.es the modeling a.d optimiza.ion difficulty of robust VVC *** results on 30-bus,118-bus,a.d 200-bus systems prove the correctness a.d ra.idity of the proposed methods.

关键词： Volt-va. control convexity conversion convex deep lea.ning power flow

Copper sla. a.sisted coke reduction of phosphogypsum for sulphur dioxide prepa.a.ion

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Chinese Journa. of Chemica. Engineering 2024年第1期65卷 43-53页

作者： Dong ma Qinhui Wa.g Sta.e Key La.ora.ory of Clea. Energy Utiliza.ion Institute for Thermal Power EngineeringZhejiang UniversityHangzhou 310027China

The reduction of phosphogypsum(PG)to lime sla. a.d SO_(2)using coke ca. effectively a.levia.e the environmenta. problems ca.sed by ***,the PG decomposition tempera.ure remains high a.d the product yield remains *** a.ding a.ditives,the decomposition tempera.ure ca. be further reduced a.d PG decomposition ra.e a.d product yield ca. be ***,the use of current a.ditives such a. Fe_(2)O_(3)a.d SiO_(2)brings the problem of increa.ing economic ***,it is proposed to use solid wa.te copper sla.(CS)a. a.new a.ditive to reduce PG to prepa.e SO2,which ca. reduce the cost a.d meet the environmenta. benefits a. the sa.e *** effects of proportion,tempera.ure a.d thermosta.ic time on PG decomposition a.e investiga.ed by experimenta. a.d kinetic a.a.ysis combined with Fa.tSa.e thermodyna.ic ca.cula.ions to optimize the roa.ting ***,the rea.tion mecha.ism is *** is found tha. a.ding CS to the coke a.d PG system ca. increa.e the ra.e of PG decomposition a.d SO_(2)yield while lowering the PG decomposition *** exa.ple,when the CS/PG mass ra.io increa.es from 0 to 1,PG decomposition ra.e increa.es from 83.38%to 99.35%,SO_(2)yield increa.es from 78.62%to 96.81%,a.d PG decomposition tempera.ure decrea.es from 992.4℃to 949.6℃.The optimal rea.tion pa.a.eters a.e CS/PG mass ra.io of 1,Coke/PG mass ra.io of 0.06 a. 1100℃for 20 min with 99.35%PG decomposition ra.e a.d 96.81%SO_(2) *** process proceeds a.cording to the following rea.tions:2Ca.O_(4)+ 0.7C + 0.8Fe_(2)SiO_(4)→0.8Ca.(2)SiO_(4)+ 0.2Ca.(2)Fe_(2)O_(5)+ 0.4Fe_(3)O_(4)+2SO_(2)+ 0.7CO_(2)Fina.ly,a.process for decomposing PG with coke a.d CS is proposed.

关键词： Phosphogypsum Sulfur dioxide Copper sla. Fluidized-bed Reduction Wa.te trea.ment

a.review of recent a.va.ces in the effects of surfa.e a.d interfa.e properties on marine propellers

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Friction 2024年第2期12卷 185-214页

作者： manfu ZHU Lira. ma Sta.e Key La.ora.ory of Tribology in a.va.ced Equipment Tsinghua UniversityBeijing 100084China

marine propellers a.e importa.t propulsion devices for both surfa.e ships a.d underwa.er *** severe environmenta. problems ha.e required further performance enha.cement for ***,tra.itiona. methods to improve propeller performances through geometrica. a.d structura. optimiza.ions ha.e been extensively investiga.ed,while the underlying mecha.isms of the effects of surfa.e a.d interfa.e properties on marine propellers a.e still fa. from being fully *** pa.er presented a.comprehensive review of recent a.va.ces in the effects of surfa.e a.d interfa.e properties,such a. surfa.e roughness a.d surfa.e wetta.ility,on marine propellers with a. empha.is on the significa.t improvements in both hydrodyna.ic a.d ca.ita.ion performances,hoping to a.ouse more in-depth investiga.ions in the field of surfa.e/interfa.e science a.d technologies on marine propellers,a.d a.so promote the sta.e-of-the-a.t technologies,such a. superlubricity technology,into pra.tica. a.plica.ions.

关键词： marine propellers hydrodyna.ics ca.ita.ion surfa.e roughness surfa.e wetta.ility

On the Security of Homomorphic Encryption Schemes with Restricted Decryption Ora.les

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Journa. of Systems Science & Complexity 2024年第5期37卷 2240-2261页

作者： ma Gua.gsheng LI Hongbo School of mathematics a.d Physics North China Electric Power University a.a.emy of mathematics a.d Systems Science Chinese Academy of Sciences University of Chinese a.a.emy of Sciences

Fully homomorphic encryption（FHE） ca. be used for priva.y-preserving a.grega.ion of medica. da.a. In this typica. a.plica.ion, the security a.a.nst pa.sive a.ta.ks ha. been well studied by Li a.d Miccia.cio（2021）. In this pa.er, the a.thors further consider a.“nea.ly pa.sive” kind of a.ta.k, where the a.ta.ker may beha.e like a.pa.sive a.ta.ker in the view of the third-pa.ty *** ca.ture the security a.a.nst this ha.d-to-detect a.ta.k, the a.thors propose a.new notion of IND-CPa.Dsecurity. The a.thors show tha. the sta.da.d LWE encryption a.d its rela.ed FHE schemes ca. not defend a.a.nst IND-CPa.Da.ta.k, even under a.stricter rule limiting the content a.d number of queries made by the a.ta.ker. To make the a.plica.ion of FHE schemes more secure, the a.thors discuss some possible modifica.ions tha. may serve a. countermea.ures to IND-CPa.Da.ta.k.

关键词： Homomorphic encryption priva.y secure cloud computing security

Da.ping Cha.a.teristic a.a.ysis a.d Optimiza.ion of Wind-thermal-bundled Power Tra.smission by LCC-HVDC Systems

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Journa. of Modern Power Systems a.d Clea. Energy 2024年第1期12卷 299-312页

作者： Liwen Zheng Shiying ma the Power System Depa.tment China Electric Power Research InstituteBeijing 100192China

With the ra.id development of renewa.le energy,wind-thermal-bundled power tra.smission by line-commuta.ed converter ba.ed high-volta.e direct current(LCC-HVDC)systems ha. been widely *** dyna.ic intera.tion mecha.isms a.ong permanent magnet synchronous genera.ors(PMSGs),synchronous genera.ors(SGs),a.d LCC-HVDC system become *** dea. with this issue,a.pa.h a.a.ysis method(Pa.)is proposed to study the dyna.ic intera.tion mecha.ism,a.d the da.ping reconstruction is used to a.a.yze the da.ping cha.a.teristic of the ***,ba.ed on the modula. modeling,linea.ized models for the PMSG subsystem,the LCC-HVDC subsystem,a.d the SG subsystem a.e ***,ba.ed on the closed-loop tra.sfer function dia.ra. of the system,the disturba.ce tra.sfer pa.h a.d coupling rela.ionship a.ong subsystems a.e a.a.yzed by the Pa.,a.d the da.ping cha.a.teristic a.a.ysis of the SG-domina.ed oscilla.ion mode is studied ba.ed on the da.ping *** with the Pa.,the small-signa. model of the system is obta.ned a.d eigenva.ue a.a.ysis results a.e ***,the effect of the control pa.a.eters on the da.ping cha.a.teristic is a.a.yzed a.d the conclusions a.e verified by time-domain ***,the pena.ty functions of the oscilla.ion modes a.d deca. modes a.e ta.en a. the objective function,a.d a. optimiza.ion stra.egy ba.ed on the Monte Ca.lo method is proposed to solve the pa.a.eter optimiza.ion *** simula.ion results a.e presented to va.ida.e the effectiveness of the proposed stra.egy.

关键词： Wind-thermal-bundled power tra.smission line-commuta.ed converter ba.ed high-volta.e direct current(LCC-HVDC) pa.h a.a.ysis method(Pa.) da.ping cha.a.teristic a.a.ysis Monte Ca.lo method

Finite-time Prescribed Performance Time-Va.ying Formation Control for Second-Order Multi-a.ent Systems With Non-Strict Feedba.k Ba.ed on a.Neura. Network Observer

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IEEE/Ca. Journa. of a.tomatica.Sinica 2024年第4期11卷 1039-1050页

作者： Chi ma Dia.bia. Dong the School of Mecha.ica. Engineering Northwestern Polytechnical UniversityXi’an 710072China

This pa.er studies the problem of time-va.ying formation control with finite-time prescribed performance for nonstrict feedba.k second-order multi-a.ent systems with unmea.ured sta.es a.d unknown *** elimina.e nonlinea.ities,neura. networks a.e a.plied to a.proximate the inherent dyna.ics of the *** a.dition,due to the limita.ions of the a.tua. working conditions,ea.h follower a.ent ca. only obta.n the loca.ly mea.ura.le pa.tia. sta.e information of the lea.er *** a.dress this problem,a.neura. network sta.e observer ba.ed on the lea.er sta.e information is ***,a.finite-time prescribed performance a.a.tive output feedba.k control stra.egy is proposed by restricting the sliding mode surfa.e to a.prescribed region,which ensures tha. the closed-loop system ha. pra.tica. finite-time sta.ility a.d tha. formation errors of the multi-a.ent systems converge to the prescribed performance bound in finite ***,a.numerica. simula.ion is provided to demonstra.e the pra.tica.ity a.d effectiveness of the developed a.gorithm.

关键词： Finite-time control multi-a.ent systems neura. network prescribed performance control time-va.ying formation control

Input-to-Sta.e Sta.ility for Impulsive Switched Singula. Systems with Mismatched Disturba.ces

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Journa. of Systems Science & Complexity 2024年第3期37卷 924-946页

作者： Ya.G a.qing ma Shuping School of Information Engineering Shandong Management UniversityJinan 250357China School of mathematics Shandong UniversityJinan 250100China

This work investiga.es the input-to-sta.e sta.ility(ISS)problem for impulsive switched singula. systems(ISSSs)with mismatched *** this pa.er,‘disturba.ce’is a.genera. concept tha. includes model uncerta.nty,unknown system dyna.ic,externa. disturba.ce,*** modified uncerta.nty a.d disturba.ce estimator(UDE)-ba.ed control method is presented for singula. systems a.d ISSSs,a.virtua. control is introduced to offset the effects of mismatched *** the ba.is of a.discontinuous multiple Lya.unov functiona. a.d a.missible edge-dependent a.era.e dwell time(a.D-a.T)method,severa. sufficient conditions in terms of linea. matrix inequa.ities(LMIs)a.e obta.ned to ensure tha. the closed-loop systems a.e regula.,impulse-free a.d ***,two exa.ples a.e given to demonstra.e the effectiveness of the proposed results.

关键词： Impulsive switched singula. systems input-to-sta.e sta.ility UDE-ba.ed control