The research on the correlation between hydrocarbon accumulations and magmatic activities has always attracted aroused much wide attention.Existing research has primarily the hydrocarbon generations capability of sour...The research on the correlation between hydrocarbon accumulations and magmatic activities has always attracted aroused much wide attention.Existing research has primarily the hydrocarbon generations capability of source rocks and the quality of reservoirs by diabase intrusions.whereas,rare systematic research has been conducted on the oiliness and enrichment mechanism.To be specific,the diabase intrusive zone,the contact metamorphic zone and the normal shale zone of the Funing Formation in the Gaoyou Sag,Subei Basin were taken as the object of this study.Moreover,in this study,the hydrocarbon generation quality,reservoir quality,and oil-bearing quality of diabase-metamorphic zone-normal shale were evaluated using X-ray diffractions,argon ion polishing-field emission scanning electron microscope,energy spectrum,rock slice/light-sheet microscopic observations,organic geochemical tests,N_(2) gas adsorption and 2D NMR tests.The results indicated that the intrusive zone,the metamorphic zone,and the normal zone were formed in order by the degree of effect of diabase intrusions.Secondly,the oil content of different parts exhibited significant heterogeneity due to the baking effect of diabase,and the metamorphic zone had the significantly better oil-bearing nature than the intrusive zone.Lastly,a distribution model was proposed for the diabase intrusive zone-metamorphic zone-normal surrounding rock zone.展开更多
We report the generation of high energy 2μm picosecond pulses from a thulium-doped fiber master oscillator power amplifier system.The all-fiber configuration was realized by a flexible large-mode area photonic crysta...We report the generation of high energy 2μm picosecond pulses from a thulium-doped fiber master oscillator power amplifier system.The all-fiber configuration was realized by a flexible large-mode area photonic crystal fiber(LMA-PCF).The amplifier output is a linearly-polarized 1.5 ns,100 kHz pulse train with a pulse energy of up to 250μJ.Pulse compression was achieved with(2+2)-pass chirped volume Bragg grating(CVBG)to obtain a 2.8 ps pulse width with a total pulse energy of 46μJ.The overall system compactness was enabled by the all-fiber amplifier design and the multi-pass CVBG-based compressor.The laser output was then used to demonstrate high-speed direct-writing capability on a temperature-sensitive biomaterial to change its topography(i.e.fabricate microchannels,foams and pores).The topographical modifications of biomaterials are known to influence cell behavior and fate which is potentially useful in many cell and tissue engineering applications.展开更多
Pyrolysis experiments were conducted on lacustrine organic-rich shale from Cangdong Sag in Bohai Bay Basin,China,to investigate the impact of hydrocarbon generation on shale pore structure evolution.Thermal evolution ...Pyrolysis experiments were conducted on lacustrine organic-rich shale from Cangdong Sag in Bohai Bay Basin,China,to investigate the impact of hydrocarbon generation on shale pore structure evolution.Thermal evolution is found to control the transformation of organic matter,hydrocarbon products characteristics,and pore structure changes.Furthermore,pore volume and specific surface area increase with increasing maturity.In low-mature stage,the retained oil content begins to increase,pore volumes show slight changes,and primary pores are occluded by the generated crude oil of high molecular weight and density.In the oil-window stage,the retained oil content rapidly increases and reaches maximum,and pore volumes gradually increase with increasing thermal maturity.At high mature stage,the retained oil content begins to decrease,and the pore volume increases considerably owing to the expulsion of liquid hydrocarbon.In over mature stage,natural gas content significantly increases and kerogen transforms to asphalt.Numerous organic pores are formed and the pore size gradually increases,resulting from the connection of organic pores caused the increasing thermal stress.This study lays a foundation for understanding variation of hydrocarbon products during the thermal evolution of lacustrine shales and its relationship with the evolution of shale reservoirs.展开更多
We demonstrate an all fiber passively mode-locked laser emitting a radially polarized beam by using a few-mode fiber Bragg grating to achieve mode selection and spectrum filtering. An offset splicing of single-mode fi...We demonstrate an all fiber passively mode-locked laser emitting a radially polarized beam by using a few-mode fiber Bragg grating to achieve mode selection and spectrum filtering. An offset splicing of single-mode fiber with four-mode fiber is utilized as a mode coupler in the laser cavity. Carbon nanotubes are introduced into the laser cavity as the saturable absorber to achieve self-start mode locking. The laser operates at 1547.5 nm with a narrow spectrum width of 0.3 nm at 30 d B. The emitted mode-locked pulses have a duration of 22.73 ps and repetition of10.61 MHz. A radially polarized beam has been obtained with high mode purity by adjusting the polarization in the laser cavity.展开更多
Lasers with high average and high peak power as well as ultrashort pulse width have been all along demanded by nonlinear optics studies,strong-field experiments,electron dynamics investigations,and ultrafast spectrosc...Lasers with high average and high peak power as well as ultrashort pulse width have been all along demanded by nonlinear optics studies,strong-field experiments,electron dynamics investigations,and ultrafast spectroscopy.While the routinely used titanium-doped sapphire(Ti:sapphire)laser faces a bottleneck in the average power upscaling,ytterbium(Yb)-doped lasers have remarkable advantages in achieving high average power.However,there is still a substantial gap of pulse width and peak power between the Ti:sapphire and Yb-doped lasers.Here we demonstrate a high-power Yb:CaAlGdO4(Yb:CALGO)regenerative amplifier system,delivering 1040 nm pulses with11 W average power,50 fs pulse width,and 3.7 GW peak power at a repetition rate of 43 k Hz,which to some extent bridges the gap between the Ti:sapphire and Yb lasers.An ultrabroadband Yb-doped fiber oscillator,specially designed spectral shapers,and Yb:CALGO gain medium with broad emission bandwidth,together with a double-end pumping scheme enable an amplified bandwidth of 19 nm and 95 fs output pulse width.To the best of our knowledge,this is the first demonstration of sub-100 fs regenerative amplifier based on Yb-doped bulk medium without nonlinear spectral broadening.The amplified pulse is further compressed to 50 fs via cascaded-quadratic compression with a simple setup,producing 3.7 GW peak power,which boosts the record of peak power from Yb:CALGO regenerative amplifiers by 1 order.As a proof of concept,pumped by the high-power,50 fs pulses,7.5–11.5μm midinfrared(MIR)generation via intrapulse difference-frequency generation is performed,without the necessity of nonlinear fiber compressors.It leads to a simple and robust apparatus,and it would find good usefulness in MIR spectroscopic applications.展开更多
Buildings worldwide account for nearly 40%of global energy consumption.The biggest energy consumer in buildings is the heating,ventilation and air conditioning(HVAC)systems.In HVAC systems,chillers account for a major...Buildings worldwide account for nearly 40%of global energy consumption.The biggest energy consumer in buildings is the heating,ventilation and air conditioning(HVAC)systems.In HVAC systems,chillers account for a major portion of the energy consumption.Maintaining chillers in good conditions through early fault detection and diagnosis is thus a critical issue.In this paper,the fault detection and diagnosis for an air-cooled chiller with air coming from outside in variable flow rates is studied.The problem is difficult since the air-cooled chiller is operating under major uncertainties including the cooling load,and the air temperature and flow rate.A potential method to overcome the difficulty caused by the uncertainties is to perform fault detection and diagnosis based on a gray-box model with parameters regarded as constants.The method is developed and verified by us in another paper for a water-cooled chiller with the uncertainty of cooling load.The verification used a Kalman filter to predict parameters of a gray-box model and statistical process control(SPC)for measuring and analyzing their variations for fault detection and diagnosis.The gray-box model in the method,however,requires that the air temperature and flow rate be nearly constant.By introducing two new parameters and deleting data points with low air flow rate,the requirement can be satisfied and the method can then be applicable for an air-cooled chiller.The simulation results show that the method with the revised model and some data points dropped improved the fault detection and diagnosis(FDD)performance greatly.It can detect both sudden and gradual air-cooled chiller capacity degradation and sensor faults as well as their recoveries.展开更多
Shallow lakes,one of the most widespread water bodies in the world,are easily shifted to a new trophic state due to external interferences.Shifting hydrologic conditions and climate change can cause cyanobacterial har...Shallow lakes,one of the most widespread water bodies in the world,are easily shifted to a new trophic state due to external interferences.Shifting hydrologic conditions and climate change can cause cyanobacterial harmful algal blooms(CyanoHABs)in shallow lakes,which pose serious threats to ecological integrity and human health.This study analyzed the effects of hydrologic and meteorological variables on cyanobacterial blooms in Yangtze-connected lakes(Lake Dongting and Poyang)and isolated lakes(Lake Chao and Tai).The results show that(i)chlorophyll-a(Chl-a)concentration tends to decrease exponentially with increasing relative lake level fluctuations(RLLF)and precipitation,but to increase linearly with increasing wind speed and air temperature;(ii)Chl-a concentrations in lakes were significantly higher when RLLF<100,precipitation<2.6 mm,wind speed>2.6 ms^(-1),or air temperature>17.8℃;(iii)the Chl-a concentration of Yangtze-isolated lakes was more significantly affected by water level amplitude,precipitation,wind speed and air temperature than the Yangtze-connected lakes;(iv)the RLLF and the ratio of wind speed to mean water depth could be innovative coupling factors to examine variation characteristics of Chl-a in shallow lakes with greater correlation than single factors.展开更多
基金financially supported by the National Natural Science Foundation of China(Grant No.42072150).
文摘The research on the correlation between hydrocarbon accumulations and magmatic activities has always attracted aroused much wide attention.Existing research has primarily the hydrocarbon generations capability of source rocks and the quality of reservoirs by diabase intrusions.whereas,rare systematic research has been conducted on the oiliness and enrichment mechanism.To be specific,the diabase intrusive zone,the contact metamorphic zone and the normal shale zone of the Funing Formation in the Gaoyou Sag,Subei Basin were taken as the object of this study.Moreover,in this study,the hydrocarbon generation quality,reservoir quality,and oil-bearing quality of diabase-metamorphic zone-normal shale were evaluated using X-ray diffractions,argon ion polishing-field emission scanning electron microscope,energy spectrum,rock slice/light-sheet microscopic observations,organic geochemical tests,N_(2) gas adsorption and 2D NMR tests.The results indicated that the intrusive zone,the metamorphic zone,and the normal zone were formed in order by the degree of effect of diabase intrusions.Secondly,the oil content of different parts exhibited significant heterogeneity due to the baking effect of diabase,and the metamorphic zone had the significantly better oil-bearing nature than the intrusive zone.Lastly,a distribution model was proposed for the diabase intrusive zone-metamorphic zone-normal surrounding rock zone.
基金Agency for Science,Technology and Research(A^*STAR)Singapore through the X-ray Photonics Programme(1426500052)A^*STAR Graduate Academy through the A^*STAR Graduate Scholarship.
文摘We report the generation of high energy 2μm picosecond pulses from a thulium-doped fiber master oscillator power amplifier system.The all-fiber configuration was realized by a flexible large-mode area photonic crystal fiber(LMA-PCF).The amplifier output is a linearly-polarized 1.5 ns,100 kHz pulse train with a pulse energy of up to 250μJ.Pulse compression was achieved with(2+2)-pass chirped volume Bragg grating(CVBG)to obtain a 2.8 ps pulse width with a total pulse energy of 46μJ.The overall system compactness was enabled by the all-fiber amplifier design and the multi-pass CVBG-based compressor.The laser output was then used to demonstrate high-speed direct-writing capability on a temperature-sensitive biomaterial to change its topography(i.e.fabricate microchannels,foams and pores).The topographical modifications of biomaterials are known to influence cell behavior and fate which is potentially useful in many cell and tissue engineering applications.
基金supported by the National Natural Science Foundation of China(Grant Nos.42072150,41372144)the State Science and Technology Major Project of China(Grant No.2017ZX05049001-008)
文摘Pyrolysis experiments were conducted on lacustrine organic-rich shale from Cangdong Sag in Bohai Bay Basin,China,to investigate the impact of hydrocarbon generation on shale pore structure evolution.Thermal evolution is found to control the transformation of organic matter,hydrocarbon products characteristics,and pore structure changes.Furthermore,pore volume and specific surface area increase with increasing maturity.In low-mature stage,the retained oil content begins to increase,pore volumes show slight changes,and primary pores are occluded by the generated crude oil of high molecular weight and density.In the oil-window stage,the retained oil content rapidly increases and reaches maximum,and pore volumes gradually increase with increasing thermal maturity.At high mature stage,the retained oil content begins to decrease,and the pore volume increases considerably owing to the expulsion of liquid hydrocarbon.In over mature stage,natural gas content significantly increases and kerogen transforms to asphalt.Numerous organic pores are formed and the pore size gradually increases,resulting from the connection of organic pores caused the increasing thermal stress.This study lays a foundation for understanding variation of hydrocarbon products during the thermal evolution of lacustrine shales and its relationship with the evolution of shale reservoirs.
基金National Natural Science Foundation of China(Grant Nos.81703379 and U1801287)Key-Area Research and Development Program of Guangdong Province(Grant No.2020B1111110007)+3 种基金Science and Technology Planning Project of Guangdong Province(Grant No.2018B020207008)Key Laboratory Program of Guangzhou(Grant 201902010082)the Specific Research Fund for TCM Science and Technology of Guangdong Provincial Hospital of Chinese Medicine(Grant Nos.YN2016QJ05 and YN2015MS03)Key Project of High-level University Construction of Guangzhou University of Chinese Medicine(Grant No.XK2018019)。
基金National Natural Science Foundation of China(NSFC)(61275049)
文摘We demonstrate an all fiber passively mode-locked laser emitting a radially polarized beam by using a few-mode fiber Bragg grating to achieve mode selection and spectrum filtering. An offset splicing of single-mode fiber with four-mode fiber is utilized as a mode coupler in the laser cavity. Carbon nanotubes are introduced into the laser cavity as the saturable absorber to achieve self-start mode locking. The laser operates at 1547.5 nm with a narrow spectrum width of 0.3 nm at 30 d B. The emitted mode-locked pulses have a duration of 22.73 ps and repetition of10.61 MHz. A radially polarized beam has been obtained with high mode purity by adjusting the polarization in the laser cavity.
基金National Natural Science Foundation of China(62075144)Engineering Featured Team Fund of Sichuan University(2020SCUNG105)。
文摘Lasers with high average and high peak power as well as ultrashort pulse width have been all along demanded by nonlinear optics studies,strong-field experiments,electron dynamics investigations,and ultrafast spectroscopy.While the routinely used titanium-doped sapphire(Ti:sapphire)laser faces a bottleneck in the average power upscaling,ytterbium(Yb)-doped lasers have remarkable advantages in achieving high average power.However,there is still a substantial gap of pulse width and peak power between the Ti:sapphire and Yb-doped lasers.Here we demonstrate a high-power Yb:CaAlGdO4(Yb:CALGO)regenerative amplifier system,delivering 1040 nm pulses with11 W average power,50 fs pulse width,and 3.7 GW peak power at a repetition rate of 43 k Hz,which to some extent bridges the gap between the Ti:sapphire and Yb lasers.An ultrabroadband Yb-doped fiber oscillator,specially designed spectral shapers,and Yb:CALGO gain medium with broad emission bandwidth,together with a double-end pumping scheme enable an amplified bandwidth of 19 nm and 95 fs output pulse width.To the best of our knowledge,this is the first demonstration of sub-100 fs regenerative amplifier based on Yb-doped bulk medium without nonlinear spectral broadening.The amplified pulse is further compressed to 50 fs via cascaded-quadratic compression with a simple setup,producing 3.7 GW peak power,which boosts the record of peak power from Yb:CALGO regenerative amplifiers by 1 order.As a proof of concept,pumped by the high-power,50 fs pulses,7.5–11.5μm midinfrared(MIR)generation via intrapulse difference-frequency generation is performed,without the necessity of nonlinear fiber compressors.It leads to a simple and robust apparatus,and it would find good usefulness in MIR spectroscopic applications.
文摘Buildings worldwide account for nearly 40%of global energy consumption.The biggest energy consumer in buildings is the heating,ventilation and air conditioning(HVAC)systems.In HVAC systems,chillers account for a major portion of the energy consumption.Maintaining chillers in good conditions through early fault detection and diagnosis is thus a critical issue.In this paper,the fault detection and diagnosis for an air-cooled chiller with air coming from outside in variable flow rates is studied.The problem is difficult since the air-cooled chiller is operating under major uncertainties including the cooling load,and the air temperature and flow rate.A potential method to overcome the difficulty caused by the uncertainties is to perform fault detection and diagnosis based on a gray-box model with parameters regarded as constants.The method is developed and verified by us in another paper for a water-cooled chiller with the uncertainty of cooling load.The verification used a Kalman filter to predict parameters of a gray-box model and statistical process control(SPC)for measuring and analyzing their variations for fault detection and diagnosis.The gray-box model in the method,however,requires that the air temperature and flow rate be nearly constant.By introducing two new parameters and deleting data points with low air flow rate,the requirement can be satisfied and the method can then be applicable for an air-cooled chiller.The simulation results show that the method with the revised model and some data points dropped improved the fault detection and diagnosis(FDD)performance greatly.It can detect both sudden and gradual air-cooled chiller capacity degradation and sensor faults as well as their recoveries.
基金The Natural Key Scientific and Technological Project for Water Pollution Control and Management(2017ZX07401-004).
文摘Shallow lakes,one of the most widespread water bodies in the world,are easily shifted to a new trophic state due to external interferences.Shifting hydrologic conditions and climate change can cause cyanobacterial harmful algal blooms(CyanoHABs)in shallow lakes,which pose serious threats to ecological integrity and human health.This study analyzed the effects of hydrologic and meteorological variables on cyanobacterial blooms in Yangtze-connected lakes(Lake Dongting and Poyang)and isolated lakes(Lake Chao and Tai).The results show that(i)chlorophyll-a(Chl-a)concentration tends to decrease exponentially with increasing relative lake level fluctuations(RLLF)and precipitation,but to increase linearly with increasing wind speed and air temperature;(ii)Chl-a concentrations in lakes were significantly higher when RLLF<100,precipitation<2.6 mm,wind speed>2.6 ms^(-1),or air temperature>17.8℃;(iii)the Chl-a concentration of Yangtze-isolated lakes was more significantly affected by water level amplitude,precipitation,wind speed and air temperature than the Yangtze-connected lakes;(iv)the RLLF and the ratio of wind speed to mean water depth could be innovative coupling factors to examine variation characteristics of Chl-a in shallow lakes with greater correlation than single factors.
