The MAHLE Group ranks amongst the top three systems suppliers worldwide for piston systems, cylinder components, valve train systems, air management systems, and liquid management systems. For almost 90 years, MAHLE h...The MAHLE Group ranks amongst the top three systems suppliers worldwide for piston systems, cylinder components, valve train systems, air management systems, and liquid management systems. For almost 90 years, MAHLE has played a decisive role in promoting the development of automotive and engine technology, setting standards time and again with 115 production plants on four continents, around 49,000 employees and sales of about 5 billion Euros in 2008.展开更多
Anaerobic digestion of Chinese cabbage waste was investigated through a pilot-scale two-stage digester at a mesophilic temperature of 37 ℃. In the acidification digester, the main product was acetic acid, with the ma...Anaerobic digestion of Chinese cabbage waste was investigated through a pilot-scale two-stage digester at a mesophilic temperature of 37 ℃. In the acidification digester, the main product was acetic acid, with the maxi- mum concentration of 4289 mg·L^-1 on the fourth day, accounting for 50.32% of total volatile fatty acids. The oxidation reduction potential （ORP） and NH^＋-N level decreased gradually with hydraulic retention time （HRT） of acidification. In the second digestion phase, the maximum methanogenic bacterial concentration reached 9.6 × 10^10ml^-1 at the organic loading rate （OLR） of 3.5-4 kg VS·m^-3, with corresponding HRT of 12-16 days. Accordingly, the optimal biogas production was 0.62 m^3· （kg VS）^-1, with methane content of 65%-68%;. ORP and NH4^＋-N levels in the methanizer remained between -500 and -560 mV and 2000-4500mg· L^-1, respec- tively. Methanococcus and Methanosarcina served as the main methanogens in the anaerobic digester.展开更多
Connected and automated vehicle(CAV) is a transformative technology that has great potential to change our daily life. Therefore, CAV related research has been advanced significantly in recent years. This paper does a...Connected and automated vehicle(CAV) is a transformative technology that has great potential to change our daily life. Therefore, CAV related research has been advanced significantly in recent years. This paper does a comprehensive review on five selected subjects that lie in the heart of CAV research:(i) inter-CAV communications;(ii) security of CAVs;(iii) intersection control for CAVs;(iv) collision-free navigation of CAVs; and(v)pedestrian detection and protection. It is believed that these topics are essential to ensure the success of CAVs and need to be better understood. For inter-CAV communications, this paper focuses on both Dedicated Short Range Communications(DSRC) and the future 5 G cellular technologies; for security of CAVs, this paper discusses both passive and active attacks and the existing solutions; for intersection control, this paper summarizes the pros and cons of both centralized and decentralized approaches; for collision avoidance, this paper concentrates on four subareas: maneuverability, vehicle networking, control confliction, and motorcycles; for pedestrian detection, this paper covers sensor, radar, and computer vision based approaches. Under each topic, this paper not only shows the stateof-the-art, but also unveils potential future research directions. By establishing connections among these subjects, this paper shows how they interact with each other and how they can be integrated into a seamless user experience. It is believed that the literature covered and conclusions drawn in this paper are very helpful to CAV researchers, application engineers, and policy makers.展开更多
The radial surface coating layer of compression piston rings is used to improve their wear resistance during the internal combustion engine operation.However,at top dead centers,the friction coefficient of the piston ...The radial surface coating layer of compression piston rings is used to improve their wear resistance during the internal combustion engine operation.However,at top dead centers,the friction coefficient of the piston ring–cylinder liner pair is detrimental to the engine’s tribological performance.In this work,dimples with different texture dimensions and densities were tested in a home-developed tribometer.The friction coefficient was measured for all samples,and for those with the best results,their wear resistance was assessed.The texture with an aspect ratio of 0.25 and a density area of 15%reported the best tribological results.展开更多
Ammonia(NH_(3))is emerging as a potential favoured fuel for longer range decarbonised heavy transport,particularly in the marine sector,predominantly due to highly favourable characteristics as an effective hydrogen c...Ammonia(NH_(3))is emerging as a potential favoured fuel for longer range decarbonised heavy transport,particularly in the marine sector,predominantly due to highly favourable characteristics as an effective hydrogen carrier.This is despite generally unfavourable combustion and toxicity attributes,restricting end use to applications where robust health and safety protocols can always be upheld.In the currently reported work,a spark ignited thermodynamic single cylinder research engine equipped with gasoline direct injection was upgraded to include gaseous ammonia port injection fuelling,with the aim of understanding maximum viable ammonia substitution ratios across the speedload operating map.The work was conducted at varied effective compression ratios under overall stoichiometric conditions,with the spark timing re-optimised for maximum brake torque at all stable logged sites.The experiments included industry standard measurements of combustion,performance,and engine-out emissions(including NH3“slip”).With a geometric compression ratio of 11.2:1,it was found possible to run the engine on pure ammonia at low engine speeds(1000-1800 rpm)and loads of 12 bar net IMEP.When progressively dropping down below this load limit an increasing amount of gasoline co-firing was required to avoid engine misfire.When operating at 1800 rpm and 12 bar net IMEP,all emissions of carbon(CO_(2),CO,unburned hydrocarbons)and NOx decreased considerably when switching to higher NH_(3) substitution ratios,with NOx reduced by~45%at 1800 rpm/12 bar when switching from pure gasoline to pure NH_(3)(associated with longer and cooler combustion).By further increasing the geometric compression ratio to 12.4 and reducing the intake camshaft duration for maximum effective compression ratio,it was possible to operate the engine on pure ammonia at much lower loads in a fully warmed up state(e.g.,linear low load limit line from 1000 rpm/6 bar net IMEP to 1800 rpm/9 bar net IMEP).Under all conditions,the indicated thermal efficiency of the engine was either equivalent to or slightly higher than that obtained using gasoline-only due to the favourable anti-knock rating of NH_(3).Ongoing work is concerned with detailed breakdown of individual NOx species together with measuring the impact of hydrogen enrichment across the operating map.展开更多
文摘The MAHLE Group ranks amongst the top three systems suppliers worldwide for piston systems, cylinder components, valve train systems, air management systems, and liquid management systems. For almost 90 years, MAHLE has played a decisive role in promoting the development of automotive and engine technology, setting standards time and again with 115 production plants on four continents, around 49,000 employees and sales of about 5 billion Euros in 2008.
基金the National Science-Technology Support Plan of China(2014BAD02B04)
文摘Anaerobic digestion of Chinese cabbage waste was investigated through a pilot-scale two-stage digester at a mesophilic temperature of 37 ℃. In the acidification digester, the main product was acetic acid, with the maxi- mum concentration of 4289 mg·L^-1 on the fourth day, accounting for 50.32% of total volatile fatty acids. The oxidation reduction potential （ORP） and NH^＋-N level decreased gradually with hydraulic retention time （HRT） of acidification. In the second digestion phase, the maximum methanogenic bacterial concentration reached 9.6 × 10^10ml^-1 at the organic loading rate （OLR） of 3.5-4 kg VS·m^-3, with corresponding HRT of 12-16 days. Accordingly, the optimal biogas production was 0.62 m^3· （kg VS）^-1, with methane content of 65%-68%;. ORP and NH4^＋-N levels in the methanizer remained between -500 and -560 mV and 2000-4500mg· L^-1, respec- tively. Methanococcus and Methanosarcina served as the main methanogens in the anaerobic digester.
文摘Connected and automated vehicle(CAV) is a transformative technology that has great potential to change our daily life. Therefore, CAV related research has been advanced significantly in recent years. This paper does a comprehensive review on five selected subjects that lie in the heart of CAV research:(i) inter-CAV communications;(ii) security of CAVs;(iii) intersection control for CAVs;(iv) collision-free navigation of CAVs; and(v)pedestrian detection and protection. It is believed that these topics are essential to ensure the success of CAVs and need to be better understood. For inter-CAV communications, this paper focuses on both Dedicated Short Range Communications(DSRC) and the future 5 G cellular technologies; for security of CAVs, this paper discusses both passive and active attacks and the existing solutions; for intersection control, this paper summarizes the pros and cons of both centralized and decentralized approaches; for collision avoidance, this paper concentrates on four subareas: maneuverability, vehicle networking, control confliction, and motorcycles; for pedestrian detection, this paper covers sensor, radar, and computer vision based approaches. Under each topic, this paper not only shows the stateof-the-art, but also unveils potential future research directions. By establishing connections among these subjects, this paper shows how they interact with each other and how they can be integrated into a seamless user experience. It is believed that the literature covered and conclusions drawn in this paper are very helpful to CAV researchers, application engineers, and policy makers.
基金supported by Fundação para a Ciência e Tecnologia(FCT)and MAHLE,Componentes de Motores,S.A.through the grant SFRH/BDE/110654/2015by the project Add-Additive with the reference POCI-01-0247-FEDER-024533.
文摘The radial surface coating layer of compression piston rings is used to improve their wear resistance during the internal combustion engine operation.However,at top dead centers,the friction coefficient of the piston ring–cylinder liner pair is detrimental to the engine’s tribological performance.In this work,dimples with different texture dimensions and densities were tested in a home-developed tribometer.The friction coefficient was measured for all samples,and for those with the best results,their wear resistance was assessed.The texture with an aspect ratio of 0.25 and a density area of 15%reported the best tribological results.
基金EPSRC-MariNH3-Grant number EP/W016656/1.Business,Energy&Industrial Strategy(BEIS).
文摘Ammonia(NH_(3))is emerging as a potential favoured fuel for longer range decarbonised heavy transport,particularly in the marine sector,predominantly due to highly favourable characteristics as an effective hydrogen carrier.This is despite generally unfavourable combustion and toxicity attributes,restricting end use to applications where robust health and safety protocols can always be upheld.In the currently reported work,a spark ignited thermodynamic single cylinder research engine equipped with gasoline direct injection was upgraded to include gaseous ammonia port injection fuelling,with the aim of understanding maximum viable ammonia substitution ratios across the speedload operating map.The work was conducted at varied effective compression ratios under overall stoichiometric conditions,with the spark timing re-optimised for maximum brake torque at all stable logged sites.The experiments included industry standard measurements of combustion,performance,and engine-out emissions(including NH3“slip”).With a geometric compression ratio of 11.2:1,it was found possible to run the engine on pure ammonia at low engine speeds(1000-1800 rpm)and loads of 12 bar net IMEP.When progressively dropping down below this load limit an increasing amount of gasoline co-firing was required to avoid engine misfire.When operating at 1800 rpm and 12 bar net IMEP,all emissions of carbon(CO_(2),CO,unburned hydrocarbons)and NOx decreased considerably when switching to higher NH_(3) substitution ratios,with NOx reduced by~45%at 1800 rpm/12 bar when switching from pure gasoline to pure NH_(3)(associated with longer and cooler combustion).By further increasing the geometric compression ratio to 12.4 and reducing the intake camshaft duration for maximum effective compression ratio,it was possible to operate the engine on pure ammonia at much lower loads in a fully warmed up state(e.g.,linear low load limit line from 1000 rpm/6 bar net IMEP to 1800 rpm/9 bar net IMEP).Under all conditions,the indicated thermal efficiency of the engine was either equivalent to or slightly higher than that obtained using gasoline-only due to the favourable anti-knock rating of NH_(3).Ongoing work is concerned with detailed breakdown of individual NOx species together with measuring the impact of hydrogen enrichment across the operating map.
