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The noise spectral characteristics and noise reduction schemes of screw air-source heat pump:A case study

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Building simulation 2024年第1期17卷 53-70页

作者： Dongsheng Liu Yaohan Feng Jikang Jia Pengfei si Ya Feng China Southwest Architecture Design and Research institute Co.Ltd. Chengdu 610041China CSCEC Green Construction Engineering Research Center Chengdu 610041China

The screw air-source heat pump can cause incessant high noise levels during operation,which might hinder adoption of this energy-efficient heat ***,acoustic measurements and comparison testing were performed in this *** measurements revealed that the compressor is the main noise source of the heat pump,and it shows a multipeak frequency distribution and a wide frequency spectrum under different work conditions,with multiple peaks at 63,250,and 1000 ***,a compressor sound insulation cover with broadband absorption was proposed,and it was experimentally proven that the insulation cover can reduce the maximum sound pressure level of one unit from 89.8 dBA to 79.1 ***,we proposed several noise reduction strategies and compared their noise reduction effects using computer *** results showed that the noise problem can be effectively improved through the rational design of the sound barrier and the layout and opening options of heat *** distance between the sound barrier and heat pump and the sound attenuation due to diffraction ALa exhibit a u-shaped *** buildings of different heights,the optimal heights of noise barrier are *** 5.5-meter is the optimal height of the sound barrier for single-story *** conclusions can be applied to other building projects for heat pump noise reduction.

关键词： acoustic simulation broadband noise noise reduction air-source heat pump sound barrier

Global Zero-relaxation Limit Problem of the Electro-diffusion Model Arising in Electro-Hydrodynamics

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Acta Mathematicae Applicatae sinica 2024年第1期40卷 241-268页

作者： Ming-hua Yang si-ming Huang Jin-yi Sun Department of Mathematics Jiangxi University of Finance and EconomicsNanchang330032China School of Public Administration Guangdong University of Foreign StudiesGuangzhou510006China College of Mathematics and Statistics Northwest Normal UniversityLanzhou730070China

in this paper,we study a global zero-relaxation limit problem of the electro-diffusion model arising in electro-hydrodynamics which is the coupled Planck-Nernst-Poisson and Navier-Stokes *** is,the paper deals with a singular limit problem of{u^(∈)_(t)+u^(∈)·▽u^(∈)-Δu^(∈)+▽P^(∈)=Δφ^(∈)▽φ^(∈),in R^(3)×(0,∞),▽·u^(∈)=0,in R^(3)×(0,∞),n^(∈)_(t)+u^(∈)·▽n^(∈)-Δn^(∈)=-▽·(n^(∈)▽φ^(∈)),in R^(3)×(0,∞),ct+u^(∈)·▽c^(∈)-Δc^(∈)=▽·(c^(∈)▽φ^(∈)),in R^(3)×(0,∞),∈^(-1)φ^(∈)_(t)=Δφ^(∈)-n^(∈)+c^(∈),in R^(3)×(0,∞),(u^(∈),n^(∈),c^(∈),φ^(∈))|t=0=(u0,n0,c0,φ0),in R^(3) involving with a positive,large parameter^(∈).The present work show a case that(u^(∈),n^(∈),c^(∈))stabilizes to(u^(∞),n∞,c∞):=(u,n,c)uniformly with respect to the time variable as^(∈)→+∞with respect to the strong topology in a certain Fourier-Herz space.

关键词： fourier-Herz space littlewood-Paley decomposition stability limit dissipative system

Phenomenology of heavy neutral gauge boson at muon collider

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Science China(Physics,Mechanics & Astronomy) 2024年第3期67卷 60-79页

作者： Zongyang Lu Honglei Li Zhi-Long Han Zong-Guo si Liuxin Zhao School of Physics and Technology University of JinanJinan 250022China School of Physics Shandong UniversityJinan 250100China

Heavy neutral gauge boson Z' is proposed in many new physics *** has rich phenomena at the future muon *** study the properties of Z' boson with the process of μ^(+)μ^(-)→qq,μ^(+)μ^(-)→l^(+)l^(-),μ^(+)μ^(-)→ ZH and μ^(+)μ^(-)→ W^(+)W^(-).The discrepancy of Z' coupling to different types of particles can be shown in the cross section distributions around the resonance peak of various decay *** distributions of the final quark or lepton in μ^(+)μ^(-)→qq/l^(+)l^(-)process are sensitive to the parameters such as mass of Z' and the Z-Z' mixing *** interaction of new gauge boson coupling to the standard model gauge particles and Higgs boson are also studied through μ^(+)μ^(-)→ ZH→l^(+)l^(-)bb and μ^(+)u^(-)→ W^(+)W^(-)→l^(+)l^(-)v_(l)v_(l).The cross section and the final particles' angular distributions with the contribution of Z' boson differ from those processes with only standard model particles.A forward-backward asymmetry defined by the angular distribution is provided to show the potential of searching for new physics at the muon ***,the beam polarization with certain value can effectively enlarge the forward-backward asymmetry.

关键词： Z′boson muon collider new physics

Highly elastic and degradable vitrimeric elastomers using polycondensation

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Chinese Chemical Letters 2024年第3期35卷 434-438页

作者： Yue Liu Yongshuang Huang Chao Li Guifu si Min Chen institutes of Physical Science and information Technology Key Laboratory of Structure and Functional Regulation of Hybrid Materials of Ministry of EducationAnhui UniversityHefei 230601China CAS Key Laboratory of Soft Matter Chemistry Department of Polymer Science and EngineeringUniversity of Science and Technology of ChinaHefei 230026China

introducing covalently crosslinked network to polymer matrix can merge the advantages in reprocessing and durability of *** this contribution,a series of high-performance vitrimeric elastomers were achieved via *** topological structures of polymers were tuned by varying the feeding ratios of bisacetoacetate,hex–substituted bisacetoacetate,bisamine and tris(2-aminoethyl)*** these structural manipulations,the vitrimeric elastomers presented great elastic recovery properties(strain recovery value up to 80%)benefiting from the introduction of long chain ***,the elastomers exhibited excellent reprocessing property,water vapor/oxygen barrier and adhesive ***,the elastomers could be degraded into monomer under acid conditions which enabled the elastomer synthesis again in closed loop recycling *** ease of the polycondensation in this work to prepare highly elastic and recyclable vitrimeric elastomers demonstrated exciting opportunities for the synthesis of sustainable polymers.

关键词： Polycondensation Vitrimeric elastomers Highly elastic Degradable polymers

Ferrihydrite transformation impacted by coprecipitation of lignin:inhibition or facilitation?

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Journal of Environmental Sciences 2024年第5期139卷 23-33页

作者： Lin Liu Zhihui Yang Weichun Yang Wen Jiang Qi Liao Mengying si Feiping Zhao School of Metallurgy and Environment Central South UniversityChangsha 410083China Chinese National Engineering Research Center for Control&Treatment of Heavy Metal Pollution(CNERC-CTHMP) Changsha 410083China

Lignin is a common soil organic matter that is present in soils,but its effect on the transformation of ferrihydrite(Fh)remains *** matter is generally assumed to inhibit Fh ***,lignin can reduce Fh to Fe(Ⅱ),in which Fe(Ⅱ)-catalyzed Fh transformation ***,the effects of lignin on Fh transformation were investigated at 75℃ as a function of the lignin/Fh mass ratio(0-0.2),pH(4-8)and aging time(0-96 hr).The results of Fh-lignin samples(mass ratios=0.1)aged at different pH values showed that for Fh-lignin the time of Fh transformation into secondary crystalline minerals was significantly shortened at pH 6 when compared with pure Fh,and the Fe(Ⅱ)-accelerated transformation of Fh was strongly dependent on *** pH 6,at low lignin/Fh mass ratios(0.05-0.1),the time of secondary mineral formation decreased with increasing lignin *** high lignosulfonate-content material(lignin:Fh=0.2),Fh did not transform into secondary minerals,indicating that lignin content plays a major role in Fh *** addition,lignin affected the pathway of Fh transformation by inhibiting goethite formation and facilitating hematite *** effect of coprecipitation of lignin on Fh transformation should be useful in understanding the complex iron and carbon cycles in a soil environment.

关键词： Ferrihydrite transformation Lignin Hematite Goethite Fe(Ⅱ)-catalyzed Reactive Fe(Ⅲ)species

Boosting thermal stability and crystallization of closed-loop-recyclable biodegradable poly(p-dioxanone) by end-group regulation

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Science China Chemistry 2024年第2期67卷 642-651页

作者： Jin Lei Zhu-Xin Gui Wan-Ting Xiong Gang Wu si-Chong Chen Yu-Zhong Wang The Collaborative innovation Center for Eco-Friendly and Fire-Safety Polymeric Materials(MoE) National Engineering Laboratory of Eco-Friendly Polymeric Materials(Sichuan)State Key Laboratory of Polymer Materials EngineeringCollege of ChemistrySichuan UniversityChengdu610064China

A chemically closed-loop-recyclable biodegradable polymer,poly(p-dioxanone)(PPDO),is one of the ideal candidates for single-use plastic products due to its suitability for different application ***,when PPDO wastes can be collected,its monomer p-dioxanone(PDO) will be obtained through chemical recycling of these wastes;when cannot be collected,the wastes are able to be biodegraded into harmless ***,unsatisfied thermal stability and low crystallization rate of PPDO restrict its wider ***,based on end-group regulation,we simultaneously realized the significant enhancement of thermal stability and crystallization of PPDO through the simple melt processing with tributyl phosphite(TBP) or triphenyl phosphite(TPP).The model reactions were conducted to investigate the reaction mechanism and theoretical products during the preparation of PPDO/phosphite *** kinds of phosphites were proved to act as the end-capped reagent and chain extender in the melt processing,while TBP presented better *** a result,the activation energy of thermal decomposition was largely elevated,and the unprecedented T_(5%)(the temperature at a weight loss of 5%) and Tmax(the temperature at a maximum rate of weight loss) of PPDO were obtained,i.e.,T_(5%)of ~330 ℃ and Tmaxof ~385 ℃ in N_(2) atmosphere,T_(5%)of ~240 ℃ and Tmaxof ~317 ℃ in air atmosphere,***,the increased crystallization rate,crystallinity,crystalline orderliness,and realizable monomer recovery(yield >90%,purity >99.9%) of PPDO/phosphite compounds were confirmed.

关键词： poly(p-dioxanone) phosphite thermal stability crystallization end-group regulation

Evolution of High-energy Electron Distribution in Pulsar Wind Nebulae

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Research in Astronomy and Astrophysics 2024年第7期24卷 201-217页

作者： Yi-Ming Liu Hou-Dun Zeng Yu-Liang Xin si-Ming Liu Yi Zhang Key Laboratory of Dark Matter and Space Astronomy Purple Mountain ObservatoryChinese Academy of Sciences School of Astronomy and Space Science University of Science and Technology of China School of Physical Science and Technology Southwest Jiaotong University

in this paper,we analyze the spectral energy distributions of 17 powerful (with a spin-down luminosity greater than1035erg s-1) young （with an age less than 15,000 yr） pulsar wind nebulae （PWNe） using a simple timein-dependent one-zone emission *** aim is to investigate correlations between model parameters and the ages of the corresponding PWNe,thereby revealing the evolution of high-energy electron distributions within *** findings are as follows:（1） The electron distributions in PWNe can be characterized by a double power-law with a super-exponential cutoff.（2） As PWNe evolve,the high-energy end of the electron distribution spectrum becomes harder with the index decreasing from approximately 3.5 to 2.5,while the low-energy end spectrum index remains constant near 1.5.（3） There is no apparent correlation between the break energy or cutoff energy and the age of PWNe.（4） The average magnetic field within PWNe decreases with age,leading to a positive correlation between the energy loss timescale of electrons at the break energy or the high-energy cutoff and the age of the PWN.（5） The total electron energy within PWNe remains constant near 2×1048erg,while the total magnetic energy decreases with age.

关键词： gamma-rays: general iSM: general iSM: supernova remnants radiation mechanisms: non-thermal

Review of the Analysis and Suppression for High-frequency Oscillations of the Grid-connected Wind Power Generation System

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CES Transactions on Electrical Machines and Systems 2024年第2期8卷 127-142页

作者： Bo Pang Qi si Pan Jiang Kai Liao Xiaojuan Zhu Jianwei Yang Zhengyou He the College of Electrical Engineering Southwest Jiaotong UniversityChengdu 610031China iEEE

High-frequency oscillation(HFO)of gridconnected wind power generation systems(WPGS)is one of the most critical issues in recent years that threaten the safe access of WPGS to the *** the WPGS can damp HFO is becoming more and more vital for the development of wind *** HFO phenomenon of wind turbines under different scenarios usually has different ***,engineers need to acquire the working mechanisms of the different HFO damping technologies and select the appropriate one to ensure the effective implementation of oscillation damping in practical *** paper introduces the general assumptions of WPGS when analyzing HFO,systematically summarizes the reasons for the occurrence of HFO in different scenarios,deeply analyses the key points and difficulties of HFO damping under different scenarios,and then compares the technical performances of various types of HFO suppression methods to provide adequate references for engineers in the application of ***,this paper discusses possible future research difficulties in the problem of HFO,as well as the possible future trends in the demand for HFO damping.

关键词： Damping method High-frequency oscillation Stability Wind power generation

Multifunctional RGD coated a single-atom iron nanozyme:A highly selective approach to inducing ferroptosis and enhancing immunotherapy for pancreatic cancer

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Nano Research 2024年第6期17卷 5469-5478页

作者： Haoqi Pan Xu Chen Mingming Xiao He Xu Jiansheng Guo Zhiyi Lu Dong Cen Xianjun Yu si Shi Department of Pancreatic Surgery Fudan University Shanghai Cancer CenterShanghai 200032China Department of Oncology Shanghai Medical CollegeFudan UniversityShanghai 200032China Shanghai Pancreatic Cancer institute Shanghai 200032China Pancreatic Cancer institute Fudan UniversityShanghai 200032China Key Laboratory of Advanced Fuel Cells and Electrolyzers Technology of Zhejiang Province Qianwan Institute of CNITECHNingbo Institute of Materials Technology and EngineeringChinese Academy of SciencesNingbo 315201China Department of Pathology of sir Run Run Shaw Hospital Zhejiang University School of MedicineHangzhou 310016China Key Laboratory of Laparoscopic Technology of Zhejiang Province Department of General SurgerySir Run Run Shaw HospitalZhejiang University School of MedicineHangzhou 310016China

Nanozyme is a new promising approach to cancer therapy for its ability to induce ferroptosis by activating H_(2)O_(2)via a traditional radical pathway and enhance cancer ***,short half-life period of hydroxyl radical(·OH)results in unsatisfied ***,we synthesized a single-atom iron nanozyme(Fe-SAzyme),which can activate H_(2)O_(2)via a non-radical pathway to generate Fe-based reactive oxygen species(ROS)(O=FeO_(3)=O)for promoting the ferroptosis of pancreatic cancer *** Fe-SAzyme could be specifically phagocytosed by pancreatic cancer cells,increasing ROS levels and inhibiting glutathione(GSH)synthesis,which activates *** magnetic resonance imaging(MRi)showed decreased T2 signal after intravenous injection of RGD@Fe-AC(AC=activated carbon).Moreover,RGD@Fe-AC promoted dendritic cell(DC)maturation,overcame Treg-mediated immunosuppression,activated T cells to trigger adaptive immune responses,and enhanced the efficacy ofα-PD-L1 *** research demonstrated that RGD@Fe-AC provided a straightforward,easily implemented,and selective approach for pancreatic cancer treatment and immunotherapy.

关键词： single-atom iron nanozyme pancreatic cancer immunotherapy ferroptosis