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Simulation and experimental improvement on a small-scale Stirling thermo-acoustic engine

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Frontiers in Energy 2016年第1期10卷 37-45页

作者： mao chen Yonglin JU Institute of Refrigeration and Cryogenics Shanghai Jiao TongUniversity Shanghai 200240 China

Compared with the traditional engines, the thermo-acoustic engines are relatively new and can act as the linear compressors for refrigerators. Many institutes have shown great interest in this kind of machine for its absence of moving mechanical part. In this paper, the influence of the dimensions of the main parts of the small- scale Stifling thermo-acoustic engine was numerically simulated using a computer code called DeltaEC. The resonator and the resonator cavity were found to be the most convenient and effective in improving the perfor- mance of the engine. Based on the numerical simulation, a small-scale Stifling thermo-acoustic engine were constructed and experimentally investigated. Currently, with a resonator length of only 1 m, the working frequency of the engine was decreased to 90 Hz and the onset temperature difference was decreased to 198.2 K.

关键词： thermo-acoustic Stifling engine small-scale simulation experiment

Existence and bifurcation of integral manifolds with applications

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Science China Mathematics 2005年第7期48卷 940-957页

作者： HAN mao'an chen Xianfeng Department of Mathematics Shanghai Normal University Shanghai 200234 China Department of Mathematics Shanghai Jiao Tong University Shanghai 200030 China

In this paper a bifurcation theorem on the existence of integral manifolds is obtained by using contracting principle. As an application, sufficient conditions for a higher dimensional system to have an integral manifold are given. Especially the existence and uniqueness of a 3-dimensional invariant torus appearing in a 4-dimensional autonomous system with singularity of codimension two are proved.

关键词： existence, bifurcation, invariant manifold, invariant torus.

Self-evident Automated Proving Based on Point Geometry from the Perspective of Wu's Method Identity

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Journal of Systems Science & Complexity 2019年第1期32卷 78-94页

作者： ZHANG Jingzhong PENG Xicheng chen mao National Engineering Research Center for E-Learning Central China Normal University Institute of Computational Science and Technology Guangzhou University Chongqing Institute of Green and Intelligent Technology Chinese Academy of Sciences

The algebraic methods represented by Wu's method have made signi?cant breakthroughs in the ?eld of geometric theorem proving. Algebraic proofs usually involve large amounts of calculations, thus making it diffcult to understand intuitively. However, if the authors look at Wu's method from the perspective of identity, Wu's method can be understood easily and can be used to generate new geometric propositions. To make geometric reasoning simpler, more expressive, and richer in geometric meaning, the authors establish a geometric algebraic system(point geometry built on nearly 20 basic properties/formulas about operations on points) while maintaining the advantages of the coordinate method, vector method, and particle geometry method and avoiding their disadvantages. Geometric relations in the propositions and conclusions of a geometric problem are expressed as identical equations of vector polynomials according to point geometry. Thereafter, a proof method that maintains the essence of Wu's method is introduced to ?nd the relationships between these equations. A test on more than 400 geometry statements shows that the proposed proof method, which is based on identical equations of vector polynomials, is simple and e?ective. Furthermore, when solving the original problem, this proof method can also help the authors recognize the relationship between the propositions of the problem and help the authors generate new geometric propositions.

关键词： Geometry algebra point geometry proof method based on identical equations vector geometry Wu's method

Molecular transformation of dissolved organic matter in refinery wastewaters: Characterized by FT-ICR MS coupled with electrospray ionization and atmospheric pressure photoionization

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Petroleum Science 2023年第1期20卷 590-599页

作者： chen He Wei-Ming chen Chun-mao chen Quan Shi State Key Laboratory of Heavy Oil Processing Beijing Key Laboratory of Oil and Gas Pollution ControlChina University of PetroleumBeijing 102249China Faculty of Geosciences and Environmental Engineering Southwest Jiaotong UniversityChengduSichuan 611756China

Dissolved organic matter(DOM)in refinery wastewater is an extremely complex mixture of various organic *** mass spectrometry,it is impossible to characterize all of the DOM molecules with only one ionization *** this study,negative-ion,electrospray ionization(ESI),positive-ion ESI,and positive-ion atmospheric pressure photoionization(APPI)were coupled with Fourier transform ion cyclotron resonance mass spectrometry(FT-ICR MS)to analyze the molecular composition of DOM in a refinery wastewater stream during the treatment *** were obvious differences in the heteroatom composition,number of DOM constituents,and chemical properties in refinery wastewater under the three ionization *** CHO and CHOS compounds detected by(+)ESI,basic CHN and CHON compounds detected by(þ)ESI,and hydrocarbons detected by(+)APPI were analyzed to determine the molecular transformations that occurred during *** an anaerobic biological treatment process,acidic CHO and CHOS compounds with a high oxygen content were preferentially removed,and acidic CHO and CHOS compounds with a low oxygen content were *** an aerobic biological process,acidic CHO and CHOS compounds with a low oxygen content were preferentially removed,and acidic CHO and CHOS compounds with a high oxygen content were *** whole biological treatment process has a poor removal efficiency for CHN and CHON compounds,and *** activated carbon(AC)adsorption process removed different heteroatom compounds mainly with a low oxygen content for acidic and basic *** transformation mechanism of CHO and CHOS compounds in the biological treatment process was analyzed by the Kendrick mass defect(KMD)theory and a mass difference network *** the anaerobic process,large amounts of oxygenated CHO and CHOS compounds were degraded by decarboxylation,deoxydation,demethoxylation,and dehydration reactions,and converted to lower oxygen content *** the aerobic

关键词： Refinery wastewater DOM Molecular transformation ESI APPI FT-ICR MS

Challenges and Recent Developments of Photoflow-Reversible Deactivation Radical Polymerization(RDRP)

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Chinese Journal of Polymer Science 2021年第9期39卷 1069-1083页

作者： Zhuo-Ran Zhong Yi-Nan chen Yang Zhou mao chen State Key Laboratory of Molecular Engineering of Polymers Department of Macromolecular ScienceFudan UniversityShanghai 200433China

Photo-controlled reversible-deactivation radical polymerizati on(photo-RDRP)has been investigated as a"green"and spatiotem-porally controlling pathway for polymer *** the combination of photo-RDRP and flow chemistry has offered opportunities to increase light intensity and enable uniform light irradiation,problems associated with flow approaches still remain for photoflow-RDRP,which has hindered merging flow polymerization with other cutting-edge ***,we summarize challenges and recent achievements in photoflow-RDRP including the development of(a)droplet/slug-flow to regulate reside nee time distribution,(b)mixing techniques to tailor polymer,(c)polymerization in duced self-assembly,and(d)computer-aided *** hope this work will provide in formative knowledge to people in related fields and stimulate novel ideas to promote polymer synthesis in both academia and industry.

关键词： Controlled radical polymerization RDRP Photopolymerization Flow chemistry Flow polymerization

Dispersity Regulation in Photo-controlled Radical Polymerization by Merging Aryl Sulfonyl Chloride Initiators and Mixed Disulfide Agents

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Chemical Research in Chinese Universities 2023年第5期39卷 816-821页

作者： ZHANG Lu ZHANG Zexi chen mao Department of Macromolecular Science State Key Laboratory of Molecular Engineering of PolymersFudan UniversityShanghai 200433P.R.China

On-demand regulation of molecular weight distribution(MWD)is crucial to influence the properties of *** this work,we reported an organocatalyzed photo-controlled radical polymerization(photo-CRP)from the tosyl chloride initiator by combining two disulfides as chain transfer *** novel synthetic protocol allows facile access toward well-defined polymers with tunable MWDs and predetermined molecular *** including structural characterization,kinetic investigation and chain-extension polymerization exhibited good chain-growth control for polymers of different *** the easy accessibility of the initiating site(sulfonyl chloride)on many aromatic sources,this work presents a promising avenue to modify such substances with polymers of tailored MWDs,chain lengths and repeating units under metal-free and mild conditions driven by light.

关键词： Reversible deactivation radical polymerization Photo-controlled radical polymerization Organocatalyst Molecular weight distribution Polymer chemistry

Computer-Aided Living Polymerization Conducted under Continuous-Flow Conditions

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Chinese Journal of Chemistry 2022年第2期40卷 285-296页

作者： Zeyu Wang Yang Zhou mao chen State Key Laboratory of Molecular Engineering of Polymers Department of Macromolecular ScienceFudan UniversityShanghai 200438China

Continuous-flow techniques have promoted the development of synthetic chemistry due to advantages such as outstanding mass/heat transfer,on-demand scalability,improved safety,precise regulation on reaction parameters,***,the combination of flow polymerization with computer scienee has gained considerable interests,leading to a variety of cutting-edge synthetic *** review summarizes emerging achievements realized via the integration of computer science and living flow polymerizations,including 1)high-throughput living polymerizations in flow,2)programmable regulations of dispersity profile,se-que nee and topology for polymers,3)modular desig n with on line mon itori ng,as well as 4)self-optimized living polymerizati ons in *** expect that this summary will furnish informative kno wledge to scie ntists in related directions and in spire new ideas to further empower on-demand polymer engineering with modern techniques.

关键词： Polymers Synthetic methods Polymerization Flow chemistry Computer-aided synthesis

Facile Control of Molecular Weight Distribution via Droplet-Flow Light-Driven Reversible-Deactivation Radical Polymerization

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Chinese Journal of Chemistry 2022年第19期40卷 2305-2312页

作者： Yang Zhou Yangkang Fu mao chen Department of Macromolecular Science State Key Laboratory of Molecular Engineering of PolymersFudan UniversityShanghai200438 China

Molecular weight distribution(MWD)is fundamental for polymer analysis,which influences many important properties of polymeric *** this work,we demonstrate the development of a computer-aided droplet-flow system that combines photo-mediated reversible-deactivation radical polymerization(RDRP)and chain transfer agent(CTA)diffusion strategy to enable facile MWD control for the first *** advantages of this photo-flow polymerization allow controlled chain-growth to yield a variety of polymers of tunable MWDs in a broad range(Ð≈1.1—1.9)with predetermined molecular weights(Mn≈4—30 kDa)and good chain-end ***,the computer-aided platform has streamlined an automatic and high-throughput pathway to prepare polymer libraries of tunable *** copolymers,chemical compositions could be readily regulated besides MWDs with the droplet-flow *** believe that this work should be attractive for polymer engineering,and informative to create more flow polymerization techniques toward on-demand control of diverse polymer characters.

关键词： Photocatalysis Copolymerization Synthetic methods Molecular weight distribution Flow chemistry

Facile synthesis of gradient copolymers enabled by droplet-flow photo-controlled reversible deactivation radical polymerization

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Science China Chemistry 2021年第5期64卷 844-851页

作者： Yang Zhou Shantao Han Yu Gu mao chen State Key Laboratory of Molecular Engineering of Polymers Department of Macromolecular ScienceFudan UniversityShanghai 200438China

Monomer sequence influences the properties and applications of ***,massive efforts have been made to implement sequence control of *** this work,we developed a computer-aided droplet-flow polymerization based on photo-controlled reversible-deactivation radical polymerization(photo-RDRP),enabling synthesis of gradient copolymers of tunable sequential arrangements,low dispersity and good structural fidelity from various monomers without following their intrinsic reactivities,which is a key limitation in sequence *** obtained gradient copolymers exhibit unique thermal properties and stimulus responsiveness comparing with the random and block counterparts,and their glass transition behaviour could be regulated by the gradient *** believe that the unprecedented gradient photo-RDRP based on flow synthesis opens a robust and versatile avenue to streamline the synthesis of well-defined gradient polymers,and is compatible with other polymerization mechanisms.

关键词： controlled radical polymerization photopolymerization gradient copolymer flow chemistry sequence control