A novel two-stroke boosted uniflow scavenged direct-injection gasoline (BUSDIG) engine has been proposed and designed in order to achieve aggressive engine downsizing and down-speeding for higher engine performance an...A novel two-stroke boosted uniflow scavenged direct-injection gasoline (BUSDIG) engine has been proposed and designed in order to achieve aggressive engine downsizing and down-speeding for higher engine performance and efficiency. In this paper, the design and development of the BUSDIG engine are outlined discussed and the key findings are summarized to highlight the progress of the development of the proposed two-stroke BUSDIG engine. In order to maximize the scavenging performance and produce sufficient in-cylinder flow motions for the fuel/air mixing process in the two-stroke BUSDIG engine, the engine bore/stroke ratio, intake scavenge port angles, and intake plenum design were optimized by three-dimensional (3D) computational fluid dynamics (CFD) simulations. The effects of the opening profiles of the scavenge ports and exhaust valves on controlling the scavenging process were also investigated. In order to achieve optimal in-cylinder fuel stratification, the mixture-formation processes by different injection strategies were studied by using CFD simulations with a calibrated Reitz–Diwakar breakup model. Based on the optimal design of the BUSDIG engine, one-dimensional (1D) engine simulations were performed in Ricardo WAVE. The results showed that a maximum brake thermal efficiency of 47.2% can be achieved for the two-stroke BUSDIG engine with lean combustion and water injection. A peak brake toque of 379 N·m and a peak brake power density of 112 kW·L^-1 were achieved at 1600 and 4000 r·min^-1, respectively, in the BUSDIG engine with the stoichiometric condition.展开更多
The authors regret to inform that several numbers/variables are mistaken due to clerical errors.1.In the first paragraph of Section 4.4,“For the short duration design with an ED of 98 CA,the EVO was gradually delayed...The authors regret to inform that several numbers/variables are mistaken due to clerical errors.1.In the first paragraph of Section 4.4,“For the short duration design with an ED of 98 CA,the EVO was gradually delayed from 101 to 141 CA”,where“101”should be“107.”2.In the figure caption of Fig.15,where“rI/E”should be“aI/E.”The authors would like to apologize for any inconvenience caused.展开更多
High-performance alloys are indispensable in modern engineering because of their exceptional strength,ductility,corrosion resistance,fatigue resistance,and thermal stability,which are all significantly influenced by t...High-performance alloys are indispensable in modern engineering because of their exceptional strength,ductility,corrosion resistance,fatigue resistance,and thermal stability,which are all significantly influenced by the alloy interface structures.Despite substantial efforts,a comprehensive overview of interface engineering of high-performance alloys has not been presented so far.In this study,the interfaces in high-performance alloys,particularly grain and phase boundaries,were systematically examined,with emphasis on their crystallographic characteristics and chemical element segregations.The effects of the interfaces on the electrical conductivity,mechanical strength,toughness,hydrogen embrittlement resistance,and thermal stability of the alloys were elucidated.Moreover,correlations among various types of interfaces and advanced experimental and computational techniques were examined using big data analytics,enabling robust design strategies.Challenges currently faced in the field of interface engineering and emerging opportunities in the field are also discussed.The study results would guide the development of next-generation high-performance alloys.展开更多
Radiative cooling systems(RCSs)possess the distinctive capability to dissipate heat energy via solar and thermal radiation,making them suitable for thermal regulation and energy conservation applications,essential for...Radiative cooling systems(RCSs)possess the distinctive capability to dissipate heat energy via solar and thermal radiation,making them suitable for thermal regulation and energy conservation applications,essential for mitigating the energy crisis.A comprehensive review connecting the advancements in engineered radiative cooling systems(ERCSs),encompassing material and structural design as well as thermal and energy-related applications,is currently absent.Herein,this review begins with a concise summary of the essential concepts of ERCSs,followed by an introduction to engineered materials and structures,containing nature-inspired designs,chromatic materials,meta-structural configurations,and multilayered constructions.It subsequently encapsulates the primary applications,including thermal-regulating textiles and energy-saving devices.Next,it highlights the challenges of ERCSs,including maximized thermoregulatory effects,environmental adaptability,scalability and sustainability,and interdisciplinary integration.It seeks to offer direction for forthcoming fundamental research and industrial advancement of radiative cooling systems in real-world applications.展开更多
This paper investigates the reliability of internal marine combustion engines using an integrated approach that combines Fault Tree Analysis(FTA)and Bayesian Networks(BN).FTA provides a structured,top-down method for ...This paper investigates the reliability of internal marine combustion engines using an integrated approach that combines Fault Tree Analysis(FTA)and Bayesian Networks(BN).FTA provides a structured,top-down method for identifying critical failure modes and their root causes,while BN introduces flexibility in probabilistic reasoning,enabling dynamic updates based on new evidence.This dual methodology overcomes the limitations of static FTA models,offering a comprehensive framework for system reliability analysis.Critical failures,including External Leakage(ELU),Failure to Start(FTS),and Overheating(OHE),were identified as key risks.By incorporating redundancy into high-risk components such as pumps and batteries,the likelihood of these failures was significantly reduced.For instance,redundant pumps reduced the probability of ELU by 31.88%,while additional batteries decreased the occurrence of FTS by 36.45%.The results underscore the practical benefits of combining FTA and BN for enhancing system reliability,particularly in maritime applications where operational safety and efficiency are critical.This research provides valuable insights for maintenance planning and highlights the importance of redundancy in critical systems,especially as the industry transitions toward more autonomous vessels.展开更多
Pre-chamber ignition technology can address the issue of uneven in-cylinder mixture combustion in large-bore marine engines.The impact of various pre-chamber structures on the formation of the mixture and jet flames w...Pre-chamber ignition technology can address the issue of uneven in-cylinder mixture combustion in large-bore marine engines.The impact of various pre-chamber structures on the formation of the mixture and jet flames within the pre-chamber is explored.This study performed numerical simulations on a large-bore marine ammonia/hydrogen pre-chamber engine prototype,considering pre-chamber volume,throat diameter,the distance between the hydrogen injector and the spark plug,and the hydrogen injector angle.Compared with the original engine,when the pre-chamber volume is 73.4 ml,the throat diameter is 14 mm,the distance ratio is 0.92,and the hydrogen injector angle is 80°.Moreover,the peak pressure in the pre-chamber increased by 23.1%,and that in the main chamber increased by 46.3%.The results indicate that the performance of the original engine is greatly enhanced by altering its fuel and pre-chamber structure.展开更多
Profile of Prof.Ning-Li Wang Academician of the Chinese Academy of Engineering(CAE)Member of the International Academy of Ophthalmology Director,Ophthalmology Center,Beijing Tongren Hospital Dean,School of Ophthalmolo...Profile of Prof.Ning-Li Wang Academician of the Chinese Academy of Engineering(CAE)Member of the International Academy of Ophthalmology Director,Ophthalmology Center,Beijing Tongren Hospital Dean,School of Ophthalmology,Capital Medical University Director,National Engineering Research Center for Ophthalmic Diagnosis and Treatment National Distinguished Physician Member,Academic Advisory Committee.展开更多
A numerical program is built to simulate the performance of a spark ignited two-stroke free-piston engine coupled with a linear generator. The computational model combines a series of dynamic and thermodynamic equatio...A numerical program is built to simulate the performance of a spark ignited two-stroke free-piston engine coupled with a linear generator. The computational model combines a series of dynamic and thermodynamic equations that are solved simultaneously to predict the performances of the engines. The dynamic analysis performed consists of an evaluation of the frictional force and load force introduced by the generator. The thermodynamic analysis used a single zone model to describe the engine＇ s working cycle which includes intake, scavenging, compression, combustion and expansion, and to evaluate the effect of heat transfer based on the first law of thermodynamics and the ideal gas state equation. Because there is no crankshaft, a time based Wiebe equation was used to express the fraction of fuel burned in the combustion. The calculated results were validated by using the experimental data from another research group. The results indicate that the free-piston generator has some advantages over conventional engines.展开更多
The in-cylinder gas exchange process is crucial to the power performance of two-stroke aircraft piston engines,which is easily influenced by complex factors such as high-altitude performance variation and in-cylinder ...The in-cylinder gas exchange process is crucial to the power performance of two-stroke aircraft piston engines,which is easily influenced by complex factors such as high-altitude performance variation and in-cylinder flow characteristics.This paper reviews the development history and characteristics of gas exchange types,as well as the current state of theory and the validation methods of gas exchange technology,while also discusses the trends of cutting-edge technologies in the field.This paper provides a theoretical foundation for the optimization and engineering design of gas exchange systems and,more importantly,points out that the innovation of gas exchange types,the modification of theoretical models,and the technology of variable airflow organization are the key future research directions in this field.展开更多
Parkinson’s disease is characterized by synucleinopathy-associated neurodegeneration.Previous studies have shown that glucagon-like peptide-1(GLP-1)has beneficial effects in a mouse model of Parkinson’s disease indu...Parkinson’s disease is characterized by synucleinopathy-associated neurodegeneration.Previous studies have shown that glucagon-like peptide-1(GLP-1)has beneficial effects in a mouse model of Parkinson’s disease induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine.However,the effect of GLP-1 on intrinsic synuclein malfunction remains unclear.In this study,we investigated the effect of Lactococcus lactis MG1363-pMG36e-GLP-1 on parkinsonism in SncaA53T transgenic mice and explored the underlying mechanisms.Our data showed that Lactococcus lactis MG1363-pMG36e-GLP-1 inhibited dopaminergic neuronal death,reduced pathological aggregation ofα-synuclein,and decreased movement disorders in SncaA53T transgenic mice.Furthermore,Lactococcus lactis MG1363-pMG36e-GLP-1 downregulated lipopolysaccharide-related inflammation,reduced cerebral activation of microglia and astrocytes,and promoted cell survival via the GLP-1 receptor/PI3K/Akt pathway in the substantia nigra.Additionally,Lactococcus lactis MG1363-pMG36e-GLP-1 decreased serum levels of pro-inflammatory molecules including lipopolysaccharide,lipopolysaccharide binding protein,interleukin-1β,and interleukin-6.Gut histopathology and western blotting further revealed that Lactococcus lactis MG1363-pMG36e-GLP-1 increased the expression of gut integrity-related proteins and reduced lipopolysaccharide-related inflammation by reversing gut dysbiosis in SncaA53T transgenic mice.Our findings showed that the beneficial effect of Lactococcus lactis MG1363-pMG36e-GLP-1 on parkinsonism traits in SncaA53T transgenic mice is mediated by microglial polarization and the reversal of dysbiosis.Collectively,our findings suggest that Lactococcus lactis MG1363-pMG36e-GLP-1 is a promising therapeutic agent for the treatment of Parkinson’s disease.展开更多
This paper presents a design for a novel,palm sized,high-aspect-ratio engine.To simplify fabrication and keep the device unobtrusive,a design incorporating a two-cycle engine having a flat,rectangular piston with spri...This paper presents a design for a novel,palm sized,high-aspect-ratio engine.To simplify fabrication and keep the device unobtrusive,a design incorporating a two-cycle engine having a flat,rectangular piston with spring return was selected.An experimental engine based on this concept producing a significant amount of useful work was developed.Although results were encouraging,this geometry raised many issues to be investigated and resolved,including the effects of piston sealing,scavenging,heat losses,and combustion efficiency.Due to the complex interplay between these effects,experimental investigation was time consuming and simple models were found to be inadequate.Therefore,a more complex theoretical model accounting for these effects was developed and used to evaluate the sensitivity of engine performance to each of these parameters.The predictions of this model were used to develop recommendations for improving the experimentally developed engine.展开更多
A frequency compensation control method for the opposed-piston two-stroke folded-cranktrain（ OPFC） diesel engine＇s common rail system is presented as a result of the study of the loop-shaping theory. A common rail ...A frequency compensation control method for the opposed-piston two-stroke folded-cranktrain（ OPFC） diesel engine＇s common rail system is presented as a result of the study of the loop-shaping theory. A common rail working process and the classical frequency control theory are combined to construct a frequency restriction of common rail pressure. A frequency compensator is utilized to improve the robustness of multiplicative perturbations and disturbance. The loop-shaping method has been applied to design the common rail pressure controller of the OPFC diesel engine. Simulation and bench test results show that in the condition of perturbation that comes from the effect of injection,multi-injection,fuel pumping of a pre-cylinder,and instantaneous pressure fluctuation,the controller indicates high precision. Compared with the original controller,this method improves the control precision by 67. 3%.展开更多
In order to study the effect of two-stage injection on two-stroke diesel engines, a well characterized research engine equipped with electronically controlled common rail system and scavenging system was constructed. ...In order to study the effect of two-stage injection on two-stroke diesel engines, a well characterized research engine equipped with electronically controlled common rail system and scavenging system was constructed. Through analysis of combustion and emissions, two-stage injection shows its advantages. Compared with the standard injection, it produces less emissions, while compared with single early injection, it expands engine operation range. Further experiments were carried out to study the influence of several injection control parameters on two-stage injection. The fuel in the first injection is used for forming homogeneous mixture. The fuel in the second injection keeps combustion, and it is the main source of smoke emissions. NO_x is formed in both combustion process caused by these two injections, and there is an optimum fuel allocation ration to produce minimum NO_x. The cylinder pressure decreases, and the combustion is depressed with the increasing of scavenging pressure. By optimizing the injection control parameters of two-stage injection, NO_x and smoke can be reduced beyond 30% simultaneously.展开更多
The effects of various split injection strategies on the opposed-piston opposed-cylinder(OPOC)diesel engine combustion and emission characteristics have been studied numerically using AVL-Fire CFD tools.The five rate-...The effects of various split injection strategies on the opposed-piston opposed-cylinder(OPOC)diesel engine combustion and emission characteristics have been studied numerically using AVL-Fire CFD tools.The five rate-shaped main injections were used in split injection strategies.The results show that ignition delay from a rectangular injection rate is the shortest.Maximum pressure of the trapezoid injection rate is the largest.And the NOx emission of the rectangular injection rate is the largest.Meanwhile,the soot emission of the trapezoid injection rate is the least among the five injection rates.展开更多
The effects of different flow forms on an opposed-piston two-stroke（OPTS）gasoline-directinjection（GDI）engine was studied by analyzing the mixture formation and combustion.Swirl was broken and dissipated gradually ...The effects of different flow forms on an opposed-piston two-stroke（OPTS）gasoline-directinjection（GDI）engine was studied by analyzing the mixture formation and combustion.Swirl was broken and dissipated gradually and the turbulence kinetic energy（TKE）was small in the compression process;however,tumble was strengthened and the TKE was strong in the compression process.For swirl around X axis（the axis of cylinder）and tumble around Y axis（the vertical direction of injector）,droplets were attached to the cylinder liner by the centrifugal force and the mixture distribution was poor.For tumble around Zaxis（the direction of injector）,the wall film in cylinder liner was thin and mixture distribution was homogeneous.Results showed that since the injector were installed on the wall of the cylinder liner in the OPTS-GDI engine,the spray angle was small and the mixture formation time was short.The 45° oblique axis tumble ratio of 1 was reasonable for the mixture formation and combustion for an OPTS-GDI engine.展开更多
Ischemic stroke is a secondary cause of mortality worldwide,imposing considerable medical and economic burdens on society.Extracellular vesicles,serving as natural nanocarriers for drug delivery,exhibit excellent bioc...Ischemic stroke is a secondary cause of mortality worldwide,imposing considerable medical and economic burdens on society.Extracellular vesicles,serving as natural nanocarriers for drug delivery,exhibit excellent biocompatibility in vivo and have significant advantages in the management of ischemic stroke.However,the uncertain distribution and rapid clearance of extracellular vesicles impede their delivery efficiency.By utilizing membrane decoration or by encapsulating therapeutic cargo within extracellular vesicles,their delivery efficacy may be greatly improved.Furthermore,previous studies have indicated that microvesicles,a subset of large-sized extracellular vesicles,can transport mitochondria to neighboring cells,thereby aiding in the restoration of mitochondrial function post-ischemic stroke.Small extracellular vesicles have also demonstrated the capability to transfer mitochondrial components,such as proteins or deoxyribonucleic acid,or their sub-components,for extracellular vesicle-based ischemic stroke therapy.In this review,we undertake a comparative analysis of the isolation techniques employed for extracellular vesicles and present an overview of the current dominant extracellular vesicle modification methodologies.Given the complex facets of treating ischemic stroke,we also delineate various extracellular vesicle modification approaches which are suited to different facets of the treatment process.Moreover,given the burgeoning interest in mitochondrial delivery,we delved into the feasibility and existing research findings on the transportation of mitochondrial fractions or intact mitochondria through small extracellular vesicles and microvesicles to offer a fresh perspective on ischemic stroke therapy.展开更多
基金financial support from the Engineering and Physical Sciences Research Council (EPSRC)
文摘A novel two-stroke boosted uniflow scavenged direct-injection gasoline (BUSDIG) engine has been proposed and designed in order to achieve aggressive engine downsizing and down-speeding for higher engine performance and efficiency. In this paper, the design and development of the BUSDIG engine are outlined discussed and the key findings are summarized to highlight the progress of the development of the proposed two-stroke BUSDIG engine. In order to maximize the scavenging performance and produce sufficient in-cylinder flow motions for the fuel/air mixing process in the two-stroke BUSDIG engine, the engine bore/stroke ratio, intake scavenge port angles, and intake plenum design were optimized by three-dimensional (3D) computational fluid dynamics (CFD) simulations. The effects of the opening profiles of the scavenge ports and exhaust valves on controlling the scavenging process were also investigated. In order to achieve optimal in-cylinder fuel stratification, the mixture-formation processes by different injection strategies were studied by using CFD simulations with a calibrated Reitz–Diwakar breakup model. Based on the optimal design of the BUSDIG engine, one-dimensional (1D) engine simulations were performed in Ricardo WAVE. The results showed that a maximum brake thermal efficiency of 47.2% can be achieved for the two-stroke BUSDIG engine with lean combustion and water injection. A peak brake toque of 379 N·m and a peak brake power density of 112 kW·L^-1 were achieved at 1600 and 4000 r·min^-1, respectively, in the BUSDIG engine with the stoichiometric condition.
文摘The authors regret to inform that several numbers/variables are mistaken due to clerical errors.1.In the first paragraph of Section 4.4,“For the short duration design with an ED of 98 CA,the EVO was gradually delayed from 101 to 141 CA”,where“101”should be“107.”2.In the figure caption of Fig.15,where“rI/E”should be“aI/E.”The authors would like to apologize for any inconvenience caused.
基金supported by the National Natural Science Foundation of China(Nos.52122408 and 52474397)the High-level Talent Research Start-up Project Funding of Henan Academy of Sciences(No.242017127)+1 种基金the financial support from the Fundamental Research Funds for the Central Universities(University of Science and Technology Beijing(USTB),Nos.FRF-TP-2021-04C1 and 06500135)supported by USTB MatCom of Beijing Advanced Innovation Center for Materials Genome Engineering。
文摘High-performance alloys are indispensable in modern engineering because of their exceptional strength,ductility,corrosion resistance,fatigue resistance,and thermal stability,which are all significantly influenced by the alloy interface structures.Despite substantial efforts,a comprehensive overview of interface engineering of high-performance alloys has not been presented so far.In this study,the interfaces in high-performance alloys,particularly grain and phase boundaries,were systematically examined,with emphasis on their crystallographic characteristics and chemical element segregations.The effects of the interfaces on the electrical conductivity,mechanical strength,toughness,hydrogen embrittlement resistance,and thermal stability of the alloys were elucidated.Moreover,correlations among various types of interfaces and advanced experimental and computational techniques were examined using big data analytics,enabling robust design strategies.Challenges currently faced in the field of interface engineering and emerging opportunities in the field are also discussed.The study results would guide the development of next-generation high-performance alloys.
基金support from the Contract Research(“Development of Breathable Fabrics with Nano-Electrospun Membrane”,CityU ref.:9231419“Research and application of antibacterial and healing-promoting smart nanofiber dressing for children’s burn wounds”,CityU ref:PJ9240111)+1 种基金the National Natural Science Foundation of China(“Study of Multi-Responsive Shape Memory Polyurethane Nanocomposites Inspired by Natural Fibers”,Grant No.51673162)Startup Grant of CityU(“Laboratory of Wearable Materials for Healthcare”,Grant No.9380116).
文摘Radiative cooling systems(RCSs)possess the distinctive capability to dissipate heat energy via solar and thermal radiation,making them suitable for thermal regulation and energy conservation applications,essential for mitigating the energy crisis.A comprehensive review connecting the advancements in engineered radiative cooling systems(ERCSs),encompassing material and structural design as well as thermal and energy-related applications,is currently absent.Herein,this review begins with a concise summary of the essential concepts of ERCSs,followed by an introduction to engineered materials and structures,containing nature-inspired designs,chromatic materials,meta-structural configurations,and multilayered constructions.It subsequently encapsulates the primary applications,including thermal-regulating textiles and energy-saving devices.Next,it highlights the challenges of ERCSs,including maximized thermoregulatory effects,environmental adaptability,scalability and sustainability,and interdisciplinary integration.It seeks to offer direction for forthcoming fundamental research and industrial advancement of radiative cooling systems in real-world applications.
基金supported by Istanbul Technical University(Project No.45698)supported through the“Young Researchers’Career Development Project-training of doctoral students”of the Croatian Science Foundation.
文摘This paper investigates the reliability of internal marine combustion engines using an integrated approach that combines Fault Tree Analysis(FTA)and Bayesian Networks(BN).FTA provides a structured,top-down method for identifying critical failure modes and their root causes,while BN introduces flexibility in probabilistic reasoning,enabling dynamic updates based on new evidence.This dual methodology overcomes the limitations of static FTA models,offering a comprehensive framework for system reliability analysis.Critical failures,including External Leakage(ELU),Failure to Start(FTS),and Overheating(OHE),were identified as key risks.By incorporating redundancy into high-risk components such as pumps and batteries,the likelihood of these failures was significantly reduced.For instance,redundant pumps reduced the probability of ELU by 31.88%,while additional batteries decreased the occurrence of FTS by 36.45%.The results underscore the practical benefits of combining FTA and BN for enhancing system reliability,particularly in maritime applications where operational safety and efficiency are critical.This research provides valuable insights for maintenance planning and highlights the importance of redundancy in critical systems,especially as the industry transitions toward more autonomous vessels.
基金Supported by the Priority Academic Program Development of Jiangsu Higher Education Institutions under Grant No.014000319/2018-00391.
文摘Pre-chamber ignition technology can address the issue of uneven in-cylinder mixture combustion in large-bore marine engines.The impact of various pre-chamber structures on the formation of the mixture and jet flames within the pre-chamber is explored.This study performed numerical simulations on a large-bore marine ammonia/hydrogen pre-chamber engine prototype,considering pre-chamber volume,throat diameter,the distance between the hydrogen injector and the spark plug,and the hydrogen injector angle.Compared with the original engine,when the pre-chamber volume is 73.4 ml,the throat diameter is 14 mm,the distance ratio is 0.92,and the hydrogen injector angle is 80°.Moreover,the peak pressure in the pre-chamber increased by 23.1%,and that in the main chamber increased by 46.3%.The results indicate that the performance of the original engine is greatly enhanced by altering its fuel and pre-chamber structure.
文摘Profile of Prof.Ning-Li Wang Academician of the Chinese Academy of Engineering(CAE)Member of the International Academy of Ophthalmology Director,Ophthalmology Center,Beijing Tongren Hospital Dean,School of Ophthalmology,Capital Medical University Director,National Engineering Research Center for Ophthalmic Diagnosis and Treatment National Distinguished Physician Member,Academic Advisory Committee.
文摘A numerical program is built to simulate the performance of a spark ignited two-stroke free-piston engine coupled with a linear generator. The computational model combines a series of dynamic and thermodynamic equations that are solved simultaneously to predict the performances of the engines. The dynamic analysis performed consists of an evaluation of the frictional force and load force introduced by the generator. The thermodynamic analysis used a single zone model to describe the engine＇ s working cycle which includes intake, scavenging, compression, combustion and expansion, and to evaluate the effect of heat transfer based on the first law of thermodynamics and the ideal gas state equation. Because there is no crankshaft, a time based Wiebe equation was used to express the fraction of fuel burned in the combustion. The calculated results were validated by using the experimental data from another research group. The results indicate that the free-piston generator has some advantages over conventional engines.
基金funded by the National Natural Science Foundation of China(Nos.52206131,U2233213and 51775025)the National Key R&D Program of China(2022YFB2602002,2018YFB0104100)+1 种基金the Zhejiang Provincial Natural Science Foundation of China(LQ22E060004)the Science Center of Gas Turbine Project,China(No.P2022-A-I-001-001)。
文摘The in-cylinder gas exchange process is crucial to the power performance of two-stroke aircraft piston engines,which is easily influenced by complex factors such as high-altitude performance variation and in-cylinder flow characteristics.This paper reviews the development history and characteristics of gas exchange types,as well as the current state of theory and the validation methods of gas exchange technology,while also discusses the trends of cutting-edge technologies in the field.This paper provides a theoretical foundation for the optimization and engineering design of gas exchange systems and,more importantly,points out that the innovation of gas exchange types,the modification of theoretical models,and the technology of variable airflow organization are the key future research directions in this field.
基金supported by grants from the Jiangxi Provincial Natural Science Foundation,No.20242BAB26134(to XF)the National Natural Science Foundation of China,Nos.82060638(to TC),82060222(to XF),82460237(to XF)+1 种基金the Major Disciplines of Academic and Technical Leaders Project of Jiangxi Province,Nos.20194BCJ22032(to TC),20213BCJL22049(to XF)Science and Technology Plan of Jiangxi Health Planning Committee,No.202210390(to XF).
文摘Parkinson’s disease is characterized by synucleinopathy-associated neurodegeneration.Previous studies have shown that glucagon-like peptide-1(GLP-1)has beneficial effects in a mouse model of Parkinson’s disease induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine.However,the effect of GLP-1 on intrinsic synuclein malfunction remains unclear.In this study,we investigated the effect of Lactococcus lactis MG1363-pMG36e-GLP-1 on parkinsonism in SncaA53T transgenic mice and explored the underlying mechanisms.Our data showed that Lactococcus lactis MG1363-pMG36e-GLP-1 inhibited dopaminergic neuronal death,reduced pathological aggregation ofα-synuclein,and decreased movement disorders in SncaA53T transgenic mice.Furthermore,Lactococcus lactis MG1363-pMG36e-GLP-1 downregulated lipopolysaccharide-related inflammation,reduced cerebral activation of microglia and astrocytes,and promoted cell survival via the GLP-1 receptor/PI3K/Akt pathway in the substantia nigra.Additionally,Lactococcus lactis MG1363-pMG36e-GLP-1 decreased serum levels of pro-inflammatory molecules including lipopolysaccharide,lipopolysaccharide binding protein,interleukin-1β,and interleukin-6.Gut histopathology and western blotting further revealed that Lactococcus lactis MG1363-pMG36e-GLP-1 increased the expression of gut integrity-related proteins and reduced lipopolysaccharide-related inflammation by reversing gut dysbiosis in SncaA53T transgenic mice.Our findings showed that the beneficial effect of Lactococcus lactis MG1363-pMG36e-GLP-1 on parkinsonism traits in SncaA53T transgenic mice is mediated by microglial polarization and the reversal of dysbiosis.Collectively,our findings suggest that Lactococcus lactis MG1363-pMG36e-GLP-1 is a promising therapeutic agent for the treatment of Parkinson’s disease.
文摘This paper presents a design for a novel,palm sized,high-aspect-ratio engine.To simplify fabrication and keep the device unobtrusive,a design incorporating a two-cycle engine having a flat,rectangular piston with spring return was selected.An experimental engine based on this concept producing a significant amount of useful work was developed.Although results were encouraging,this geometry raised many issues to be investigated and resolved,including the effects of piston sealing,scavenging,heat losses,and combustion efficiency.Due to the complex interplay between these effects,experimental investigation was time consuming and simple models were found to be inadequate.Therefore,a more complex theoretical model accounting for these effects was developed and used to evaluate the sensitivity of engine performance to each of these parameters.The predictions of this model were used to develop recommendations for improving the experimentally developed engine.
基金Supported by the National Natural Science Foundation of China(51406013)
文摘A frequency compensation control method for the opposed-piston two-stroke folded-cranktrain（ OPFC） diesel engine＇s common rail system is presented as a result of the study of the loop-shaping theory. A common rail working process and the classical frequency control theory are combined to construct a frequency restriction of common rail pressure. A frequency compensator is utilized to improve the robustness of multiplicative perturbations and disturbance. The loop-shaping method has been applied to design the common rail pressure controller of the OPFC diesel engine. Simulation and bench test results show that in the condition of perturbation that comes from the effect of injection,multi-injection,fuel pumping of a pre-cylinder,and instantaneous pressure fluctuation,the controller indicates high precision. Compared with the original controller,this method improves the control precision by 67. 3%.
基金The National Basic Research Program of China(973 Program)(No.2001CB209208)The National Science Foundation of China(No.50136040)
文摘In order to study the effect of two-stage injection on two-stroke diesel engines, a well characterized research engine equipped with electronically controlled common rail system and scavenging system was constructed. Through analysis of combustion and emissions, two-stage injection shows its advantages. Compared with the standard injection, it produces less emissions, while compared with single early injection, it expands engine operation range. Further experiments were carried out to study the influence of several injection control parameters on two-stage injection. The fuel in the first injection is used for forming homogeneous mixture. The fuel in the second injection keeps combustion, and it is the main source of smoke emissions. NO_x is formed in both combustion process caused by these two injections, and there is an optimum fuel allocation ration to produce minimum NO_x. The cylinder pressure decreases, and the combustion is depressed with the increasing of scavenging pressure. By optimizing the injection control parameters of two-stage injection, NO_x and smoke can be reduced beyond 30% simultaneously.
基金Supported by the National Natural Science Foundation of China(51605447)
文摘The effects of various split injection strategies on the opposed-piston opposed-cylinder(OPOC)diesel engine combustion and emission characteristics have been studied numerically using AVL-Fire CFD tools.The five rate-shaped main injections were used in split injection strategies.The results show that ignition delay from a rectangular injection rate is the shortest.Maximum pressure of the trapezoid injection rate is the largest.And the NOx emission of the rectangular injection rate is the largest.Meanwhile,the soot emission of the trapezoid injection rate is the least among the five injection rates.
基金Supported by the National Natural Science Foundation of China(B2220110005)
文摘The effects of different flow forms on an opposed-piston two-stroke（OPTS）gasoline-directinjection（GDI）engine was studied by analyzing the mixture formation and combustion.Swirl was broken and dissipated gradually and the turbulence kinetic energy（TKE）was small in the compression process;however,tumble was strengthened and the TKE was strong in the compression process.For swirl around X axis（the axis of cylinder）and tumble around Y axis（the vertical direction of injector）,droplets were attached to the cylinder liner by the centrifugal force and the mixture distribution was poor.For tumble around Zaxis（the direction of injector）,the wall film in cylinder liner was thin and mixture distribution was homogeneous.Results showed that since the injector were installed on the wall of the cylinder liner in the OPTS-GDI engine,the spray angle was small and the mixture formation time was short.The 45° oblique axis tumble ratio of 1 was reasonable for the mixture formation and combustion for an OPTS-GDI engine.
基金supported by the grants from University of Macao,China,Nos.MYRG2022-00221-ICMS(to YZ)and MYRG-CRG2022-00011-ICMS(to RW)the Natural Science Foundation of Guangdong Province,No.2023A1515010034(to YZ)。
文摘Ischemic stroke is a secondary cause of mortality worldwide,imposing considerable medical and economic burdens on society.Extracellular vesicles,serving as natural nanocarriers for drug delivery,exhibit excellent biocompatibility in vivo and have significant advantages in the management of ischemic stroke.However,the uncertain distribution and rapid clearance of extracellular vesicles impede their delivery efficiency.By utilizing membrane decoration or by encapsulating therapeutic cargo within extracellular vesicles,their delivery efficacy may be greatly improved.Furthermore,previous studies have indicated that microvesicles,a subset of large-sized extracellular vesicles,can transport mitochondria to neighboring cells,thereby aiding in the restoration of mitochondrial function post-ischemic stroke.Small extracellular vesicles have also demonstrated the capability to transfer mitochondrial components,such as proteins or deoxyribonucleic acid,or their sub-components,for extracellular vesicle-based ischemic stroke therapy.In this review,we undertake a comparative analysis of the isolation techniques employed for extracellular vesicles and present an overview of the current dominant extracellular vesicle modification methodologies.Given the complex facets of treating ischemic stroke,we also delineate various extracellular vesicle modification approaches which are suited to different facets of the treatment process.Moreover,given the burgeoning interest in mitochondrial delivery,we delved into the feasibility and existing research findings on the transportation of mitochondrial fractions or intact mitochondria through small extracellular vesicles and microvesicles to offer a fresh perspective on ischemic stroke therapy.
