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Design of a novel side-mounted leg mechanism with high flexibility for a multi-mission quadruped earth rover BJTUBOT

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机械工程前沿:英文版 2023年第2期18卷 115-142页

作者： Yifan Wu Sheng GUO Luquan LI Lianzheng NIU Xiao LI School of Mechanical Electronic and Control EngineeringBeijing Jiaotong UniversityBeijing 100044China

Earth rover is a class of emerging wheeled-leg robots for nature exploration.At present,few methods for these robots’leg design utilize a side-mounted spatial parallel mechanism.Thus,this paper presents a complete design process of a novel 5-degree-of-freedom(5-DOF)hybrid leg mechanism for our quadruped earth rover BJTUBOT.First,a general approach is proposed for constructing the novel leg mechanism.Subsequently,by evaluating the basic locomotion task(LT)of the rover based on screw theory,we determine the desired motion characteristic of the sidemounted leg and carry out its two feasible configurations.With regard to the synthesis method of the parallel mechanism,a family of concise hybrid leg mechanisms using the 6-DOF limbs and an L1F1C limb(which can provide a constraint force and a couple)is designed.In verifying the motion characteristics of this kind of leg,we select a typical(3-UPRU&RRRR)&R mechanism and then analyze its kinematic model,singularities,velocity mapping,workspace,dexterity,statics,and kinetostatic performance.Furthermore,the virtual quadruped rover equipped with this innovative leg mechanism is built.Various basic and specific LTs of the rover are demonstrated by simulation,which indicates that the flexibility of the legs can help the rover achieve multitasking.

关键词： design synthesis parallel mechanism hybrid leg mechanism screw theory quadruped robot

State-Based Opacity Verification of Networked Discrete Event Systems Using Labeled Petri Nets

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IEEE/CAA Journal of Automatica Sinica 2024年第5期11卷 1274-1291页

作者： yifan Dong Naiqi wu Zhiwu Li The authors are with the Institute of Systems Engineering Macao University of Science and TechnologyTaipa 999078MacaoChina

The opaque property plays an important role in the operation of a security-critical system,implying that pre-defined secret information of the system is not able to be inferred through partially observing its behavior.This paper addresses the verification of current-state,initial-state,infinite-step,and K-step opacity of networked discrete event systems modeled by labeled Petri nets,where communication losses and delays are considered.Based on the symbolic technique for the representation of states in Petri nets,an observer and an estimator are designed for the verification of current-state and initial-state opacity,respectively.Then,we propose a structure called an I-observer that is combined with secret states to verify whether a networked discrete event system is infinite-step opaque or K-step opaque.Due to the utilization of symbolic approaches for the state-based opacity verification,the computation of the reachability graphs of labeled Petri nets is avoided,which dramatically reduces the computational overheads stemming from networked discrete event systems.

关键词： infinite system symbolic

Sustained delivery of vascular endothelial growth factor mediated by bioactive methacrylic anhydride hydrogel accelerates peripheral nerve regeneration after crush injury

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Neural Regeneration Research 2022年第9期17卷 2064-2071页

作者： Wanlin Xu Yifan Wu Hao Lu Yun Zhu Jinhai Ye Wenjun Yang Department of Oral and Maxillofacial-Head and Neck Oncology Shanghai Ninth People’s HospitalShanghai Jiao Tong University School of MedicineCollege of StomatologyShanghai Jiao Tong UniversityNational Center for StomatologyNational Clinical Research Center for Oral DiseasesShanghai Key Laboratory of StomatologyShanghaiChina Jiangsu Key Laboratory of Oral Diseases Department of Oral and Maxillofacial SurgeryThe Affiliated Stomatological Hospital of Nanjing Medical UniversityNanjingJiangsu ProvinceChina

Neurotrophic factors,currently administered orally or by intravenous drip or intramuscular injection,are the main method for the treatment of peripheral nerve crush injury.However,the low effective drug concentration arriving at the injury site results in unsatisfactory outcomes.Therefore,there is an urgent need for a treatment method that can increase the effective drug concentration in the injured area.In this study,we first fabricated a gelatin modified by methacrylic anhydride hydrogel and loaded it with vascular endothelial growth factor that allowed the controlled release of the neurotrophic factor.This modified gelatin exhibited good physical and chemical properties,biocompatibility and supported the adhesion and proliferation of RSC96 cells and human umbilical vein endothelial cells.When injected into the epineurium of crushed nerves,the composite hydrogel in the rat sciatic nerve crush injury model promoted nerve regeneration,functional recovery and vascularization.The results showed that the modified gelatin gave sustained delivery of vascular endothelial growth factors and accelerated the repair of crushed peripheral nerves.

关键词： bioactive material controlled release crush injury hydrogel muscle function nerve regeneration peripheral nerve sciatic function index vascular endothelial growth factor vascularization

Environmental Mn(Ⅱ) enhances the activity of dissimilatory arsenate-respiring prokaryotes from arsenic-contaminated soils

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Journal of Environmental Sciences 2023年第3期125卷 582-592页

作者： Yan wu Weiwei wu yifan Xu Yanxia Zuo Xian-Chun Zeng State Key Laboratory of Biogeology and Environmental Geology&School of Environmental Studies China University of Geosciences(Wuhan)Wuhan 430074China Institute of Hydrobiology the Chinese Academy of SciencesWuhan 430072China

Many investigations suggest that dissimilatory arsenate-respiring prokaryotes (DARPs) play a key role in stimulating reductive mobilization of As from solid phase into groundwater,but it is not clear how environmental Mn(Ⅱ) affects the DARPs-mediated reductive mobilization of arsenic.To resolve this issue,we collected soil samples from a realgar tailingsaffected area.We found that there were diverse arsenate-respiratory reductase (arr) genes in the soils.The microbial communities had high arsenate-respiring activity,and were able to efficiently stimulate the reductive mobilization of As.Compared to the microcosms without Mn(Ⅱ),addition of 10 mmol/L Mn(Ⅱ) to the microcosms led to 23.99%-251.79% increases in the microbial mobilization of As,and led to 133.3%-239.2% increases in the abundances of arr genes.We further isolated a new cultivable DARP,Bacillus sp.F11,from the arseniccontaminated soils.It completely reduced 1 mmol/L As(V) in 5 days under the optimal reaction conditions.We further found that it was able to efficiently catalyze the reductive mobilization and release of As from the solid phase;the addition of 2 mmol/L Mn(Ⅱ) led to 98.49%-248.78% increases in the F11 cells-mediated reductive mobilization of As,and70.6%-104.4% increases in the arr gene abundances.These data suggest that environmental Mn(Ⅱ) markedly increased the DARPs-mediated reductive mobilization of As in arseniccontaminated soils.This work provided a new insight into the close association between the biogeochemical cycles of arsenic and manganese.

关键词： dissimilatory arsenate-respiring prokaryote Arsenic mobilization Arsenic-contaminated groundwater Arsenate reduction Mn(II)

Novel Radiation-Adjustable Heating Terminal Based on Flat Heat Pipe Combined with Air Source Heat Pump

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Engineering 2023年第1期20卷 192-207页

作者： Yifan Wu Hongli Sun Mengfan Duan Borong Lin Hengxin Zhao Chaohung Liu Department of Building Science Tsinghua UniversityBeijing 100084China Key Laboratory of Eco Planning and Green Building Ministry of EducationTsinghua UniversityBeijing 100084China

The electrification of building heating is an effective way to meet the global carbon target. As a clean and sustainable electrified heating technology, air-source heat pumps (ASHPs) are widely used in areas lacking central heating. However, as a major component of space heating, heating terminals might not fit well with ASHP in order to achieve both intermittency and comfort. Therefore, this study proposes a novel radiation-adjustable heating terminal combined with an ASHP to achieve electrification, intermittency, and better thermal comfort. Radiant terminals currently suffer from three major problems: limited maximum heating capacity, inability to freely adapt, and difficulty with combining them with ASHPs. These problems were solved by improving the structural design of the novel terminal (Improvement A–E). Results showed that the maximum heating capacity increased by 23.6% and radiation heat transfer ratio from 10.1% to 30.9% was provided for users with the novel terminal. Further, new flat heat pipe (FHP) design improved stability (compressor oil return), intermittency (refrigerant thermal inertia), and safety (refrigerant leakage risk) by reducing the length of exposed refrigerant pipes. Furthermore, a new phased operation strategy was proposed for the novel terminal, and the adjustability of the terminal was improved. The results can be used as reference information for decarbonizing buildings by electrifying heating terminals.

关键词： Novel heating terminal Air-source heat pump Structural impr ovement design Maximum heating capacity Rapid adjustability Room temperature distribution

Theoretical and numerical studies of chorus waves: A review

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Science China Earth Sciences 2020年第1期63卷 78-92页

作者： Xin TAO Fulvio ZONCA Liu CHEN Yifan Wu CAS Key Laboratory of Geospace Environment Department of Geophysics and Planetary SciencesUniversity of Science and Technology of ChinaHefei 230026China CAS Center for Excellence in Comparative Planetology Hefei 230026China ENEA Centro Ricerche Frascati CP 65-00044 FrascatiItaly Institute of Fusion Theory and Simulation and Department of Physics Zhejiang UniversityHangzhou 310027China Department of Physics and Astronomy University of CaliforniaIrvineCA 92697USA

Theoretical and numerical models of chorus waves are reviewed in this paper. Specifically, we focus on the nonlinear wave particle interactions and the current understanding of the frequency chirping of rising tone chorus waves. Various other related topics, such as the optimal excitation condition of chorus, the formation of subpackets, and the non-adiabaticity of the nonlinear interaction are also discussed. We end this review paper with a short list of questions of chorus waves that are still under research and debate.

关键词： Chorus waves Frequency chirping Triggered emissions

Origin of hydrogen in aromatic and olefin products derived from(Al-)MCM-41 catalysed co-pyrolysis of glucose and polypropylene via isotopic

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Clean Energy 2023年第2期7卷 253-262页

作者： Junjie Xue Jiankun Zhuo Yifan Wu Mingnuo Jin Mufei Sun Qiang Yao New Energy Generation National Engineering Research Center North China Electric Power UniversityBeijing 102206China Key Laboratory for Thermal Science and Power Engineering of Ministry of Education Tsinghua UniversityBeijing 100084China Beijing Engineering Research Center for Ecological Restoration and Carbon Fixation of Saline–alkaline and Desert Land Tsinghua UniversityBeijing 100084China

Catalytic co-pyrolysis of biomass and plastic is an effective method to improve bio-oil produced by biomass pyrolysis.To further exploit the synergistic mechanism between biomass and plastic,co-pyrolysis of polypropylene(PP)and deuterated glucose(G)(1:1 wt%)over mesoporous catalysts MCM-41(M)and Al-MCM-41(Al)was studied using a thermal gravimetric analyser(TGA)and pyrolysis-gas chromatography-mass spectrometry.The findings show that M and Al overlap the decomposition of PP and G,making synergy possible.With catalysts M and Al,the yield of olefins increases sharply to 36.75% and 13.66% more than the calculated value.Additionally,hydrogen transfers from G to 4C-13C olefins and aromatic products are influenced by the catalysts.Without a catalyst,there is no deuterium in all the co-pyrolytic products.However,catalysts M and Al can help transfer one to four deuterium atoms from G to the products.M and Al provide the pool for the intermediates of PP and G to form synergetic products.Additionally,Al helps break the carbon chain and transfer more deuterium into the products by reducing carbon atoms.

关键词： co-pyrolysis synergism hydrogen transfer isotope deuterium

Preparation and acoustic properties of high-temperature acoustic emission sensor based on La_(3)Ga_(5)SiO_(14) crystal

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Journal of Advanced Dielectrics 2024年第1期14卷 25-32页

作者： Jingxiang Si Changhong Yang Rui Guo Yifan Wu Xiujuan Lin Shifeng Huang Shandong Provincial Key Laboratory of Preparation and Measurement of Building Materials University of Jinan Jinan 250022P.R.China

With the rapid development of modern industries,the high-temperature piezoelectric sensors that can work in extreme environments are in great demand.In this work,langasite(La_(3)Ga_(5)SiO_(14),LGS),as a high-temperature piezoelectric crystal with stable electro-elastic performance,is used as core element,and air and porous Al_(2)O_(3) are selected as backing layers respectively to prepare two kinds of high-temperature acoustic emission(AE)sensors.The detection sensitivities at 25–500℃ are analyzed by the ball falling test and Hsu–Nielsen experiment.Under the condition of 25–500℃,the received amplitude signals by both sensors are maintained above 90 dB stimulated by the ZrO_(2) ceramic ball dropping.In the Hsu–Nielsen experiment,as the temperature rising from 25℃ to 500℃,the signal amplitude of sensor with air backing layer decays from 447 mV to 365 mV,while the signal amplitude varies from 270 mV to 203 mV for the sensor with porous Al_(2)O_(3) backing layer.Signiffcantly,compared with the bandwidth of the air-backing sensor(37–183 kHz),the sensor with porous Al_(2)O_(3) backing layer broadens bandwidth to 28–273 kHz.These results show that both these AE sensors have strong and stable response ability to AE signals at high-temperature of 500℃.Therefore,piezoelectric AE sensor based on LGS has great potential application in the ffeld of high-temperature structural health monitoring.

关键词： La_(3)Ga_(5)SiO_(14) acoustic emission sensor sensitivity structural health monitoring

A Rigid Nanoplatform for Precise and Responsive Treatment of Intracellular Multidrug-Resistant Bacteria

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Engineering 2022年第8期8卷 57-66页

作者： Shaoqi Qu Xiaoyong Huang Xiangbin Song Yifan Wu Xiaowei Ma Jianzhong Shen Kui Zhu National Center for Veterinary Drug Safety Evaluation College of Veterinary MedicineChina Agricultural UniversityBeijing 100193China Guangdong Laboratory for Lingnan Modern Agricultur

Antibiotic treatment failure against life-threatening bacterial pathogens is typically caused by the rapid emergence and dissemination of antibiotic resistance.The current lack of antibiotic discovery and development urgently calls for new strategies to combat multidrug-resistant(MDR)bacteria,especially those that survive in host cells.Functional nanoparticles are promising intracellular drug delivery systems whose advantages include their high biocompatibility and tunable surface modifications.Inspired by the fact that the rigidity of nanoparticles potentiates their cellular uptake,rigidity-functionalized nanoparticles(RFNs)coated with bacteria-responsive phospholipids were fabricated to boost endocytosis,resulting in the increased accumulation of intracellular antibiotics.Precise delivery and high antibacterial efficacy were demonstrated by the clearing of 99%of MDR bacteria in 4 h using methicillin-resistant Staphylococcus aureus(MRSA)and pathogenic Bacillus cereus as models.In addition,the subcellular distribution of the RFNs was modulated by altering the phospholipid composition on the surface,thereby adjusting the electrostatic effects and reprograming the intracellular behavior of the RFNs by causing them to accurately target lysosomes.Finally,the RFNs showed high efficacy against MRSA-associated infections in animal models of wound healing and bacteremia.These findings provide a controllable rigidity-regulated delivery platform with responsive properties for precisely reprograming the accumulation of cytosolic antibiotics,shedding light on precision antimicrobial therapeutics against intracellular bacterial pathogens in the future.

关键词： Antibiotic Bacteria Mesoporous silica Phospholipid Rigidity