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Digital switched hydraulics

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Frontiers of Mechanical Engineering 2018年第2期13卷 225-231页

作者： min pan Andrew PLUMMER Centre for Power Transmission and Motion Control Department of Mechanical Engineering University of Bath BA2 7AY Bath UK

This paper reviews recent developments in digital switched hydraulics particularly the switched inertance hydraulic systems （SIHSs）. The performance of SIHSs is presented in brief with a discussion of several possible configurations and control strategies. The soft switching technology and high-speed switching valve design techniques are discussed. Challenges and recommendations are given based on the current research achievements.

关键词： digital hydraulics switched inertance hydraulic systems energy efficiency high-speed switching valve fluid-borne noise

Aerobic N_2O emission for activated sludge acclimated under different aeration rates in the multiple anoxic and aerobic process

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Journal of Environmental Sciences 2016年第5期28卷 70-79页

作者： Huoqing Wang Yuntao Guan min pan Guangxue Wu Key Laboratory of Microorganism Application and Risk Control of Shenzhen Graduate School at Shenzhen Tsinghua University Environmental Science and Technology Xiamen University of Technology

Nitrous oxide（N_2O） is a potent greenhouse gas that can be emitted during biological nitrogen removal. N_2O emission was examined in a multiple anoxic and aerobic process at the aeration rates of 600 m L/min sequencing batch reactor（SBRL） and 1200 m L/min（SBRH）.The nitrogen removal percentage was 89% in SBRLand 71% in SBRH, respectively. N_2O emission mainly occurred during the aerobic phase, and the N_2O emission factor was 10.1%in SBRLand 2.3% in SBRH, respectively. In all batch experiments, the N_2O emission potential was high in SBRLcompared with SBRH. In SBRL, with increasing aeration rates, the N_2O emission factor decreased during nitrification, while it increased during denitrification and simultaneous nitrification and denitrification（SND）. By contrast, in SBRHthe N_2O emission factor during nitrification, denitrification and SND was relatively low and changed little with increasing aeration rates. The microbial competition affected the N_2O emission during biological nitrogen removal.

关键词： Aeration rate Nitrous oxide Biological nitrogen removal Multiple anoxic and aerobic Nitrite accumulation

Adaptive ant-based routing in wireless sensor networks using Energy~* Delay metrics

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2008年第4期9卷 531-538页

作者： Yao-feng WEN Yu-quan CHEN min pan State Specialized Laboratory of Biomedical Sensors Zhejiang University Hangzhou 310027 China

To find the optimal routing is always an important topic in wireless sensor networks (WSNs). Considering a WSN where the nodes have limited energy, we propose a novel Energy*Delay model based on ant algorithms ("E&D ANTS" for short) to minimize the time delay in transferring a fixed number of data packets in an energy-constrained manner in one round. Our goal is not only to maximize the lifetime of the network but also to provide real-time data transmission services. However, because of the tradeoff of energy and delay in wireless network systems, the reinforcement learning (RL) algorithm is introduced to train the model. In this survey, the paradigm of E&D ANTS is explicated and compared to other ant-based routing algorithms like AntNet and AntChain about the issues of routing information, routing overhead and adaptation. Simulation results show that our method performs about seven times better than AntNet and also outperforms AntChain by more than 150% in terms of energy cost and delay per round.

关键词： Ant colony optimization (ACO) Pheromones Power consumption Wireless sensor networks (WSNs)

Evolution and impacts of the United States’Arctic strategy and China’s responses

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Advances in Polar Science 2023年第2期34卷 144-152页

作者： LIAO Junjie pan min School of Political Science and International Relations Tongji UniversityShanghai 200092China

On 7 October,2022,the Biden administration released an updated version of the National Strategy for the Arctic Region based on new developments in the Arctic region and global *** strategy emphasizes traditional security issues in the Arctic,attaches great importance to climate governance in the region,and advocates for restoring American leadership through international *** view of the strong influence of the United States(U.S.)in the Arctic region,the changes of the *** strategy will inevitably have an impact on China’s scientific researchrights,economic interests,and governance rights in the Arctic *** respond to the new situation brought about by the changes in the *** strategy,China should take the initiative to maintain positive relationships with all Arctic countries,and continue its active participation in Arctic affairs.

关键词： the United States’Arctic strategy Arctic security Arctic governance

Experimental study of an insert and its influence on churning losses in a high-speed electro-hydrostatic actuator pump of an aircraft

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Chinese Journal of Aeronautics 2019年第8期32卷 2028-2036页

作者： Junhui ZHANG Ying LI Bing XU min pan Qun CHAO The State Key Laboratory of Fluid Power and Mechatronic Systems Zhejiang UniversityHangzhou 310027China Department of Mechanical Engineering University of BathBath BA2 7AYUnited Kingdom

The speed of an Electro-Hydrostatic Actuator(EHA) pump can recently reach 20000 r/min, and its churning losses increase obviously with an increasing speed, which results in low efficiency and thus increasing heat in aircraft EHA systems. In order to reduce churning losses at high speeds, more attention should be given to the design of an insert. In this paper, the effect of an insert with different design parameters on churning losses is investigated through Computational Fluid Dynamics(CFD) simulation and experiments by calculating the difference between churning losses torques of the test pump with and without the insert based on a high-speed churning losses test *** results show that the gap between the insert and the cylinder is critical for churning losses reduction. It is found that the churning losses of the test pump can be reduced with a decreasing gap between the cylinder block and the insert at high speeds. This is because the insert can decrease the turbulence occurrence at high speeds. The results can be used for flow field analysis and optimization of the high-speed EHA pump and provide a new method for improving efficiency of high-speed EHA pumps.

关键词： Churning losses Efficiency Electro-hydrostatic actuator pump High speed Insert

Effects of splined shaft bending rigidity on cylinder tilt behaviour for high-speed electrohydrostatic actuator pumps

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Chinese Journal of Aeronautics 2019年第2期32卷 499-512页

作者： Junhui ZHANG Yuan CHEN Bing XU min pan Qun CHAO The State Key Laboratory of Fluid Power and Mechatronic Systems Zhejiang University Department of Mechanical Engineering University of Bath

High-speed axial piston pumps are hydraulic power supplies for electro-hydrostatic actuators(EHAs). The efficiency of a pump directly affects the operating performance of an EHA, and an understanding of the physical phenomena occurring in the cylinder/valve plate interface is essential to investigate energy dissipation. The effects of the splined shaft bending rigidity on the cylinder tilt behaviour in an EHA pump need to be considered, because the deflection and radial expansion of a steel shaft rotating at a high speed cannot be ignored. This paper proposes a new mathematical model to predict the cylinder tilt behaviour by establishing a quantitative relationship between the splined shaft deflection, the cylinder tilt angle, and the tilt azimuth angle. The moments exerted by the splined shaft are included in the equilibrium equation of the cylinder. The effects of solid and hollow splined shafts equipped in an EHA pump prototype are compared at variable speeds of 5000–10,000 r/min. With a weight saving of 29.7%, the hollow shaft is experimentally found to have almost no influence on the volumetric efficiency, but to reduce the mechanical efficiency by 0.6–2.4%. The results agree with the trivial differences of the simulated central gap heights of the interface between the two shafts and the enlargement of the simulated tilt angles by the hollow shaft. The findings could guide designs of the cylinder/valve plate interface and the splined shaft to improve both the efficiency and power density of an EHA pump.

关键词： Electro-hydrostatic actuator pump Mathematical models Rigidity Splined shaft deflection Tilt behaviour prediction

Effects of Proactive Fiscal Policy in the Context of Supply-Side Structural Reform:On the Choice of Anchors for Monetary Policy

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Frontiers of Economics in China-Selected Publications from Chinese Universities 2023年第3期18卷 336-362页

作者： pan min ZHANG Xinping Center for Economic Development Research(CEDR) Wuhan UniversityWuhan 430072China Economics and Management School Wuhan UniversityWuhan 430072China

By constructing a New Keynesian dynamic stochastic general equilibrium(DSGE)model that embeds structural fiscal policy and contains two types of households,labor intermediaries,manufacturers,the central bank,and fiscal departments,and based on China's macroeconomic controls that combine proactive fiscal policy with prudent monetary policy in the context of supply-side structural reform,this paper compares and analyzes the macroeconomic effects of the various types of proactive fiscal policy instruments,and measures the impact of the choice of anchors for monetary policy on the long-term welfare loss caused by the various fiscal policy *** study finds that the consumption-oriented fiscal expenditure increase and labor income tax reduction policies have the most significant macroeconomic stimulus effects in the short term,but attention should be paid to the disadvantage that they may lead to the rise of government debt risks;and in the long term,the role of production-oriented fiscal expenditure policies in guaranteeing the stable operations of China's economy should be brought into *** addition,once the implementation of proactive fiscal policy lasts for too long,their long-term effects may be weakened,with negative macroeconomic *** order to mitigate the resulting long-term economic fluctuations and welfare loss,prudent monetary policy should be fine-tuned with price stability as the anchor.

关键词： fiscal policy monetary policy choice of anchors welfare loss

Conductivity of Poly(methyl methacrylate)/Polystyrene/Carbon Black and Poly(ethyl methacrylate)/Polystyrene/Carbon Black Ternary Composite Films

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Chinese Journal of Polymer Science 2020年第3期38卷 288-297,I0007页

作者： Hua-Gen Xu Mu-Chao Qu Ya-min pan Dirk WSchubert Institute of Polymer Materials Friedrich-Alexander-University Erlangen-NurembergMartensstr.791058 ErlangenGermany College of Materials Science and Engineering The Key Laboratory of Material Processing and Mold of Ministry of EducationZhengzhou UniversityZhengzhou 450002China Bavarian Polymer Institute Dr.Mack-Strasse 7790762 FiirthGermany

Poly(methyl methacrylate)(PMMA)/polystyrene(PS)/carbon black(CB)and poly(ethyl methacrylate)(PEMA)/PS/CB ternary composite films were obtained using solution casting technique to investigate double percolation *** both PMMA/PS/CB and PEMA/PS/CB ternary composite films,the CB particles prefer to locate into PS phase based on the results of calculating wetting coefficient,which is also confirmed by SEM *** conductivity of the films was investigated,and the percolation threshold(￠c)of both ternary composite films with different polymer blend ratios was determined by fitting the McLachlan GEM *** of PMMA/PS/CB ternary composite films showed a typical double percolation ***,due to the double emulsion structure of PEMA/PS polymer blends,the PEMA/PS/CB ternary composite films(PEMA/PS=50/50)showed a higher￠c,even CB only located in PS phase,which conflicts with the double percolation effect.A schematic diagram combined with SEM images was proposed to explain this phenomenon.

关键词： Double percolation effect Conductivity Ternary composite films Compatibility

A Study of Coordinating China's Two-Pillar Regulatory Policy under the Shock of the Fed's Interest Rate Hike-From the Perspective of"Stable Growth"and"Risk Prevention"

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China Finance and Economic Review 2023年第1期12卷 24-47页

作者： Yuhuan Yi min pan College of Finance and Statistics Hunan University

Domestic asset price fluctuations triggered by the impact of the Fed's interest rate hike may lead to a spiral of mutual feedback between fluctuations in real economy and systematic risks of the financial *** constructing a DSGE model of small-scale open economy including cross-border capital flows and supply-demand financial frictions,this paper describes the negative feedback mechanism formed by the interplay between domestic real-economy fluctuations and financial risks on both supply and demand sides under the impact of Fed's interest rate hike,and studies how to coordinate monetary policy and macroprudential policies under the goals of maintaining stable growth and preventing risks.

关键词： Fed's monetary policy two-pillar regulatory policy financial frictions on supply and demand sides DSGE model