Black carbon(BC)is considered the second largest anthropogenic climate forcer,but the radiative effects of BC are highly correlated with its combustion sources.On-road vehicles are an important source of anthropogenic...Black carbon(BC)is considered the second largest anthropogenic climate forcer,but the radiative effects of BC are highly correlated with its combustion sources.On-road vehicles are an important source of anthropogenic BC.However,there are major uncertainties in the estimates of the BC emissions from on-road light-duty passenger vehicles(LDPVs),and results obtained with the portable emissions measurement system(PEMS)method are particularly lacking.We developed a PEMS platform and evaluated the on-road BC emissions from ten in-use LDPVs.We demonstrated that the BC emission factors(EFs)of gasoline direction injection(GDI)engine vehicles range from 1.10 to 1.56 mg.km^(-1),which are higher than the EFs of port fuel injection(PFI)engine vehicles(0.10–0.17 mg.km^(-1))by a factor of 11.The BC emissions during the cold-start phase contributed 2%–33%to the total emissions.A strong correlation(R^(2)=0.70)was observed between the relative BC EFs and average vehicle speed,indicating that traffic congestion alleviation could effectively mitigate BC emissions.Moreover,BC and particle number(PN)emissions were linearly correlated(R^(2)=0.90),and compared to PFI engine vehicles,the instantaneous PN-to-BC emission rates of GDI engine vehicles were less sensitive to vehicle specific power-to-velocity(VSPV)increase in all speed ranges.展开更多
Currently, daylighting ducts system is widely used as a daylighting device. Generally, daylighting duct system efficiently takes light from outside during the day, and conveys daylight to required location through lig...Currently, daylighting ducts system is widely used as a daylighting device. Generally, daylighting duct system efficiently takes light from outside during the day, and conveys daylight to required location through light duct manufactured by high reflectance mirror. Daylighting duct system can convey daylight to underground space that has no windows opening to external space. Daylighting system is composed of light collection part, light guide part and light emission part. Efficiency of daylighting system is depending on type of each part used in the system. However, it is very difficult to estimate exact light flow in the system considering type of the parts. Authors performed measurement experiments to make clear the light flow with real-size model and miniature model of daylighting duct system. We discussed effect of type of the parts on efficiency of daylighting duct system.展开更多
Although stimulus frequency otoacoustic emissions (SFOAEs) have been used as a non-invasive measure of cochlear mechanics, clinical and experimental application of SFOAEs has been limited by difficulties in accurately...Although stimulus frequency otoacoustic emissions (SFOAEs) have been used as a non-invasive measure of cochlear mechanics, clinical and experimental application of SFOAEs has been limited by difficulties in accurately deriving quantitative information from sound pressure measured in the ear canal. In this study, a novel signal processing method for multicomponent analysis (MCA) was used to measure the amplitude and delay of the SFOAE. This report shows the delay-frequency distribution of the SFOAE measured from the human ear. A low level acoustical suppressor near the probe tone significantly suppressed the SFOAE, strongly indicating that the SFOAE was generated at characteristic frequency locations. Information derived from this method may reveal more details of cochlear mechanics in the human ear.展开更多
Non-road equipment is one of the key contributing sources to air pollution.Thus,an accurate development of emission inventory from non-road equipment is imperative for air quality management,especially for equipment w...Non-road equipment is one of the key contributing sources to air pollution.Thus,an accurate development of emission inventory from non-road equipment is imperative for air quality management,especially for equipment with a large population such as diesel-fueled forklifts.The objective of this paper is to characterize duty-cycle based emissions from diesel-fueled forklifts using a portable emission measurement system(PEMS).Three dutycycles were defined in this study,including idling,moving,and working(active duty operation)and used to characterize in-use emissions for diesel-fueled forklifts.A total of twelve diesel-fueled forklifts were selected for real-world emission measurements.Results showed that fuel-based emission factors appear to have smaller variability compared to time-based ones.For example,the time-based emission factors for CO,HC,NO,and PM 2.5 for forklifts were estimated to be 16.6-43.9,5.3-15.1,26.2-49.9,5.5-11.1 g/hr with the fuel-based emission factors being 12.1-20.3,4.1-8.3,19.1-32.4,3.5-6.5 g/kg-fuel,respectively.NO emissions appear to be the biggest concern for emissions control.Furthermore,most of the emissions factors estimated from this study are significantly different from those in both National Guideline for Emission Inventory Development for Non-Road Equipment in China and welldeveloped emission factor models such as NONROAD by US EPA.This implies that localized,preferably fuel-based emission factors should be adjusted based on real-world emission measurements in order to develop a representative emission inventory for non-road equipment.展开更多
The Sichuan Basin is one of the vital basins in China,boasting abundant hydrocarbon reservoirs.To clarify the intensity of the tectonic stress field of different tectonic episodes since the Mesozoic and to identify th...The Sichuan Basin is one of the vital basins in China,boasting abundant hydrocarbon reservoirs.To clarify the intensity of the tectonic stress field of different tectonic episodes since the Mesozoic and to identify the regional dynamic background of different tectonic movements in the Sichuan Basin and its adjacent areas,the characteristics of the acoustic emission in rocks in different strata of these areas were researched in this paper.Meanwhile,the tectonic stress magnitude in these areas since the Mesozoic was restored.The laws state that the tectonic stress varied with depth was revealed,followed by the discussion of the influence of structural stress intensity on structural patterns in different tectonic episodes.These were conducted based on the paleostress measurement by acoustic emission method and the inversion principle of the stress fields in ancient periods and the present,as well as previous research achievements.The results of this paper demonstrate that the third episode of Yanshanian Movement(Yanshanian III)had the maximum activity intensity and tremendously influenced the structural pattern in the study area.The maximum horizontal principal stress of Yanshanian III varied with depth as follows:0.0168 x+37.001(MPa),R^2=0.8891.The regional structural fractures were mainly formed in Yanshanian III in Xujiahe Formation,west Sichuan Basin,of which the maximum paleoprincipal stress ranging from 85.1 MPa to 120.1 MPa.In addition,the law stating the present maximum horizontal principal stress varies with depth was determined to be 0.0159 x+10.221(MPa),R^2=0.7868 in Wuling Mountain area.Meanwhile,it was determined to be 0.0221 x+9.4733(MPa),R^2=0.9121 in the western part of Xuefeng Mountain area and 0.0174 x+10.247(MPa),R^2=0.8064 in the whole study area.These research results will not only provide data for the simulation of stress field,the evaluation of deformation degree,and the prediction of structural fractures,but also offer absolute geological scientific bases for the elevation of favorable shale gas preservation.展开更多
Spectroscopy in the soft X-ray and extreme ultraviolet （XEUV） region is very im- portant in magnetic fusion research. Recently, two fiat-field spectrometers that utilize a varied line spacing grating to image the sp...Spectroscopy in the soft X-ray and extreme ultraviolet （XEUV） region is very im- portant in magnetic fusion research. Recently, two fiat-field spectrometers that utilize a varied line spacing grating to image the spectra of 1-13 nm and 5-50 nm were installed on EAST for core impurity emission monitoring and impurity transport study. The instruments were proven to be capable of observing spectral lines from low-Z impurities （Li, C, O, N, Ar, etc.） and highly ionized medium- and high-Z impurities （Fe, Cr, Ni, Cu, Mo, etc.）. For example, spectra in the wavelength intervals of 1-2 nm and 5-13 nm contained strong metal lines~ especially molybdenum lines during H-mode phases. Argon and nitrogen lines were also observed, which were injected for diagnostic purposes. Impurity lines were identified and compared to measurements on other magnetic fusion research devices. Detailed measurements of radial emission profiles from various impurity line emissions were also presented.展开更多
A total of 14 in-use diesel buses were selected to conduct emission measurement using a portable emissions measurement system （PEMS） in Beijing. Their instantaneous gaseous emission rates, particular matter （PM） e...A total of 14 in-use diesel buses were selected to conduct emission measurement using a portable emissions measurement system （PEMS） in Beijing. Their instantaneous gaseous emission rates, particular matter （PM） emission rates and driving parameters were obtained. The influences of speed, acceleration and vehicle specific power （VSP） on emissions were analyzed. Based on the relationships between these driving parameters and emissions, 24 driving bins defined by speed, ac- celeration and VSP were constructed with cluster analysis to group emission rates for Euro Ⅲ and IV buses, respectively. Then the emissions reductions from Euro Ⅲ to Euro Ⅳ diesel buses were ana- lyzed. Lastly, on-road hot-stabilized emission rate model for diesel buses in Beijing was developed. Through the comparison of the model simulation emission rates with the measured emission rates, the modeled emission results were in good agreement with the measured emission results. In most of the cases, the differences were less than 12 %.展开更多
The experiments of two-alpha emission from 17,18^Ne excited levels were performed at the HIRFL-RIBLL facility of the Institute of Modern Physics, Lanzhou. The beams of 17^Ne at the energy of 49.9 MeV/u and lSNe at 51....The experiments of two-alpha emission from 17,18^Ne excited levels were performed at the HIRFL-RIBLL facility of the Institute of Modern Physics, Lanzhou. The beams of 17^Ne at the energy of 49.9 MeV/u and lSNe at 51.8 MeV/u bombarded a 197Au target to populate excited states of 17,18^Ne via Coulomb excitation. Complete kinematics measurements were achieved by the detectors of a silicon strip and CsI＋PIN array. The experimental results combined with simple MC simulations show the characteristic of sequential two-alpha emission via 140 excited states for lSNe. The results of two-alpha emission from 17^Ne are preliminary and need further analyses.展开更多
Greenhouse gas emissions are increas- ing every year and their effect on the environment is becoming increasingly serious. In 2009, the concen- tration of carbon dioxide in the earth＇s atmosphere reached 387 μL/L, t...Greenhouse gas emissions are increas- ing every year and their effect on the environment is becoming increasingly serious. In 2009, the concen- tration of carbon dioxide in the earth＇s atmosphere reached 387 μL/L, the highest level in recorded histo- ry. This paper summarizes the global carbon emission situation, sources of greenhouse gases, and the con-tribution of agriculture to the accumutauon ot green- house gases. Several scientific measures are proposed to reduce greenhouse gas emissions resulting from ru- minant production such as improving animal perform- ance, regulating the rumen environment, and reduc- ing the amount of greenhouse gases emitted from live- stock manure.展开更多
Climate change is widely recognized as the major environmental problem facing the globe today. One of the most urgent environmental problems facing shipping industry is the reduction of GHG （greenhouse gas） emission...Climate change is widely recognized as the major environmental problem facing the globe today. One of the most urgent environmental problems facing shipping industry is the reduction of GHG （greenhouse gas） emissions from its operations. Given the growing concern of the international community on ＂the deep reduction of global GHG emissions＂, it cannot be expected that the non-regulation of maritime GHG emissions can further continue. This paper investigates the main challenges and threats of the development of two MBMs （market-based measures） for the reduction of GHG emissions from international shipping, i.e., the ＂global levy scheme on maritime GHG emissions＂ and the ＂maritime emission trading scheme＂. A SWOT （strengths weaknesses opportunities threat） analysis is used, in this survey, to evaluate the environmental effectiveness as well as the easiness of implementation of the two policy options. Moreover, we make apparent their strengths and weaknesses concerning abatement of maritime GHG emissions. Given the fact that the discussion regarding the implementation of some MBMs with maritime GHG-emission reduction potential is still carried out with the exception of EEDI （energy efficiency design index） and SEEMP （ship energy efficiency management plan）, this paper＇s results present special significance, as they could be further analyzed and taken into account during the adoption of any future MBM for the reduction of maritime GHG emissions.展开更多
This study investigated the emission characteristics of ultra.fine particles based on test bench and on-board measurements. The bench test results showed the ultrafine particle number concentration of the diesel engin...This study investigated the emission characteristics of ultra.fine particles based on test bench and on-board measurements. The bench test results showed the ultrafine particle number concentration of the diesel engine to be in the range of （0.56-8.35）×10^8 cm^-3. The on-board measurement results illustrated that the ultra_fine particles were strongly correlated with changes in real-world driving cycles. The particle number concentration was down to 2.0 ×10^6 cm^-3 and 2.7 ×10^7 cm^-3 under decelerating and idling operations and as high as 5.0×10^8 cm^-3 under accelerating operation. It was also indicated that the particle number measured by the two methods increased with the growth of engine load at each engine speed in both cases. The particle number presented a ＂U＂ shaped distribution with changing speed at high engine load conditions, which implies that the particle number will reach its lowest level at medium engine speeds. The particle sizes of both measurements showed single mode distributions. The peak of particle size was located at about 50-80 nm in the accumulation mode particle range. Nucleation mode particles will significantly increase at low engine load operations like idling and decelerating caused by the high concentration of unburned organic compounds.展开更多
Spectral technology has become an important detection method due to its advantages such as non- intrusive measurement and on-line analysis. In this paper, two applications of spectral technology in thermal detection w...Spectral technology has become an important detection method due to its advantages such as non- intrusive measurement and on-line analysis. In this paper, two applications of spectral technology in thermal detection were proposed. First, a novel spectroscopic method based on Planck＇s law for measurement of emissivity was introduced. The emissivity, obtained by comparing the radiation intensity of the blackbody which had the same temperature as the flame with the detected intensity of the flames, could be used for on-line measurements and had a relatively higher upper tempera- ture limit. Then, a spectroscopic method for composition detection of blended fuels was proposed based on the emissivity measured. By comparing the spectra of blended fuels and single fuels, the ratio of single fuels of the blended fuel could be calculated. The measurement system proposed in this paper, which consists of a spectrometer and a computer, is very compact.展开更多
The land surface broadband emissivity (LSBE) is a key parameter for estimatingsurface radiation, and there have been many studies of the LSBE at global orlocal scales. However, few studies have validated the surface e...The land surface broadband emissivity (LSBE) is a key parameter for estimatingsurface radiation, and there have been many studies of the LSBE at global orlocal scales. However, few studies have validated the surface emissivity databasewith multi-point field measurement data using infrared radiometry, especially inChina. In this study, we focus on the validation of the emissivity product of theglobal land surface satellite (GLASS) LSBE database for northern China for theperiod from 2006 to 2011. Specifically, we have employed an eight-day averaged,gridded emissivity product in the 813.5 mm spectral range produced at a spatialresolution of 1000 m from the Moderate Resolution Imaging Spectrometeralbedo product using a new algorithm. The GLASS LSBE database was validatedover bare surfaces with field measurement data from sand samples collected atmany pseudo-invariant sand dune sites located in western and northwesternChina. By comparing measured emissivity for different land surface types atdifferent sites and different times, it was shown that the results were consistentand that the accuracy of the field measurements was reliable. The results of thevalidation of GLASS LSBE with these field emissivity data showed very goodagreement.展开更多
The University of Birmingham has pioneered and adapted the use of the medical imaging technique known as positron emission tomography （PET） to the study of particulate, granular and multiphase flows in industrial an...The University of Birmingham has pioneered and adapted the use of the medical imaging technique known as positron emission tomography （PET） to the study of particulate, granular and multiphase flows in industrial and physical processes, This paper provides a review of the PET and complimentary positron emission particle tracking （PEPT） techniques and details their application to the study of particulate sys- tems, The current state of the art, recent developments and example results from many of the applications to which these techniques have been applied are highlighted.展开更多
The objective of this paper is to quantify the variability in emissions of off-road equipment using a portable emission measurement system.A total of 53 commonly used equipment for agriculture,base construction,paving...The objective of this paper is to quantify the variability in emissions of off-road equipment using a portable emission measurement system.A total of 53 commonly used equipment for agriculture,base construction,paving construction,and material handling were selected.Time-based and fuel-based emissions were quantified by different duty and engine modes.Three duty modes(idling,moving,and working)were used.Ten engine modes were defined based on normalized engine revolutions-per-minute and manifold absolute pressure,respectively.Composite emission factors taking into account both duty modes and its corresponding time percentage during a typical duty cycle were estimated.Results showed that there existed a large off-road equipment variability in emissions.Depending on duty and engine modes,time-based NO emissions ranged from 3.1 to 237.9,29.1‒1475.6,83.2‒681.6,and 3.2‒385.2 g/h for agriculture,base construction,paving construction and material handling equipment,respectively while for fuel-based NO emissions these ranges were 5.3‒52.0,11.7‒69.0,4.8‒30.8,and 11.0‒54.6 g/kg,respectively.Furthermore,emission factors derived from this study exhibited a much larger variability compared to those used in NONROAD by US EPA and National Guideline for Off-road Equipment of China.This implied that localized measurements of emissions are needed for improvement of accuracy of emission inventory.Furthermore,both equipment types and operations should be considered for development of emission inventory and control strategy.展开更多
Cities generate more than 60%of carbon emissions and are the main battleground for achieving the target.However,there is no unified and standardized measurement methods of carbon emissions in cities.In this paper,we t...Cities generate more than 60%of carbon emissions and are the main battleground for achieving the target.However,there is no unified and standardized measurement methods of carbon emissions in cities.In this paper,we took Xi’an as an example and started by measuring carbon emissions with the new standards.Then,the decoupling of economic development from carbon emissions was studied according to the Tapio decoupling theory.Based on the generalized Divisia index method,the decoupling effort model was proposed to study the impact of carbon emission factors contributing to carbon reduction.The results show:(i)During the period 1995–2021,the carbon emissions of Xi’an increased rapidly,with an average annual growth rate of 6.06%,due to the accelerating pace of urbanization and industrialization.(ii)The energy consumption sector accounted for the largest share of carbon emissions,ranging from 77.38%to 89.46%.Xi’an’s energy structure is primarily based on fossil fuels,especially coal,which holds a significant proportion.To achieve the“double carbon”goal,it is crucial to reduce the dependence on fossil fuels.(iii)The 10th Five-Year Plan was in the state of“expansive coupling”,while other periods were in the“weak decoupling”state from the 9th to 14th Five-Year Plan periods.After the carbon peak year in the 15th Five-Year Plan,it would be in a state of“strong decoupling”.The agricultural production account was the first to achieve a“strong decoupling”state.(iv)The government of Xi’an made efforts to decouple,but these were not enough.Technological innovation played a crucial role in the carbon reduction of Xi’an,and was a key factor in achieving the“double carbon”goal.展开更多
The real-world fuel efficiency and exhaust emission profiles of CO, HC and NOx for light-duty diesel vehicles were investigated. Using a portable emissions measurement system, 16 diesel taxies were tested on different...The real-world fuel efficiency and exhaust emission profiles of CO, HC and NOx for light-duty diesel vehicles were investigated. Using a portable emissions measurement system, 16 diesel taxies were tested on different roads in Macao and the data were normalized with the vehicle specific power bin method. The 11 Toyota Corolla diesel taxies have very good fuel economy of （5.9 ± 0.6） L/100 km, while other five diesel taxies showed relatively high values at （8.5 ± 1.7） L/100 km due to the variation in transmission systems and emission control strategies. Compared to similar Corolla gasoline models, the diesel cars confirmed an advantage of ca. 20% higher fuel efficiency. HC and CO emissions of all the 16 taxies are quite low, with the average at （0.05 ± 0.02） g/km and （0.38 ± 0.15） g/km, respectively. The average NOx emission factor of the 11 Corolla taxies is （0.56 ± 0.17） g/km, about three times higher than their gasoline counterparts. Two of the three Hyundai Sonata taxies, configured with exhaust gas recirculation （EGR） ＋ diesel oxidation catalyst （DOC） emission control strategies, indicated significantly higher NO2 emissions and NO2/NOx ratios than other diesel taxies and consequently trigger a concern of possibly adverse impacts on ozone pollution in urban areas with this technology combination. A clear and similar pattern for fuel consumption and for each of the three gaseous pollutant emissions with various road conditions was identified. To save energy and mitigate CO2 emissions as well as other gaseous pollutant emissions in urban area, traffic planning also needs improvement.展开更多
Particulate pollution was a critical challenge to the promise of good air quality during the 2008 Beijing Olympic Games,which took place from August 8th to 24th.To ensure good air quality for the Games,several tempora...Particulate pollution was a critical challenge to the promise of good air quality during the 2008 Beijing Olympic Games,which took place from August 8th to 24th.To ensure good air quality for the Games,several temporary emission control measures were implemented in Beijing and surrounding areas.Ambient particulate matter concentration decreased significantly during the Olympic period;however,it is difficult to distinguish the effectiveness of those control measures since meteorology also affects ambient PM_(2.5) concentration.In this work,a multiple linear regression model based on continuous field monitoring at a roadside site was conducted to evaluate the effects of meteorology and emission control measures on the reduction of PM_(2.5) during the 2008 Olympic Games.The hourly data set was divided into two time periods,the no control period,June 22nd to July 4th,and the control period,July 28th to August 21st.The response variable was PM_(2.5) and the meteorology covariates used in the model were hourly temperature,dew point temperature,wind speed and precipitation.Wind direction was not a significant predictor of PM_(2.5) levels in either the control or the no control period.Using the meteorologically-based regression coefficients from the two time periods,meteorology was found to contribute to at least a 16%reduction in PM_(2.5) levels in the roadside microenvironment;while the pollution control measures contributed to at least a 43%reduction in PM_(2.5) levels.展开更多
A database of real-world diesel vehicle emission factors, based on type and technology, has been developed following tests on more than 300 diesel vehicles in China using a portable emission measurement system. The da...A database of real-world diesel vehicle emission factors, based on type and technology, has been developed following tests on more than 300 diesel vehicles in China using a portable emission measurement system. The database provides better understanding of diesel vehicle emissions under actual driving conditions. We found that although new regulations have reduced real-world emission levels of diesel trucks and buses significantly for most pollutants in China, NOx emissions have been inadequately controlled by the current standards, especially for diesel buses, because of bad driving conditions in the real world. We also compared the emission factors in the database with those calculated by emission factor models and used in inventory studies. The emission factors derived from COPERT（Computer Programmer to calculate Emissions from Road Transport） and MOBILE may both underestimate real emission factors, whereas the updated COPERT and PART5（Highway Vehicle Particulate Emission Modeling Software） models may overestimate emission factors in China. Real-world measurement results and emission factors used in recent emission inventory studies are inconsistent,which has led to inaccurate estimates of emissions from diesel trucks and buses over recent years. This suggests that emission factors derived from European or US-based models will not truly represent real-world emissions in China. Therefore, it is useful and necessary to conduct systematic real-world measurements of vehicle emissions in China in order to obtain the optimum inputs for emission inventory models.展开更多
With the increasing international consensus concerning the negative effects of climate change,reducing greenhouse gases has become a higher priority in government policies and research committees.The transportation se...With the increasing international consensus concerning the negative effects of climate change,reducing greenhouse gases has become a higher priority in government policies and research committees.The transportation sector generates approximately 29%of the total greenhouse gas emissions and 25%of the global energy related carbon dioxide(CO2)emissions.Thus,it is essential to understand the influencing factors of vehicle emissions and establish a corresponding evaluation model for the emission estimation of operating vehicles.This paper reviews different methods of measuring vehicle emissions,including laboratory measurements,on-road measurements,and tunnel measurements.Then,we summarize the factors affecting the emission evaluation of operating vehicles based on the vehicle operating features and road environment.Finally,the applications of vehicle emission evaluation models are analyzed,including the emission assessment of the vehicles operating at road segments and intersections.Based on this review,one can conclude that selecting different measurements will significantly impact the assessment of the vehicle emission results and the applicable scope of the measurements.Considering the different influencing factors of the operating vehicle emissions will have an impact on the model application of the vehicle emission evaluation.Moreover,several analysis methods for new technology vehicles can compensate for the potential lack in connectedness with the rapid development of new energy vehicle technology and the improvement of intelligent transportation systems(ITS).展开更多
基金supported by the National Natural Science Foundation of China(51708327 and 51978404)。
文摘Black carbon(BC)is considered the second largest anthropogenic climate forcer,but the radiative effects of BC are highly correlated with its combustion sources.On-road vehicles are an important source of anthropogenic BC.However,there are major uncertainties in the estimates of the BC emissions from on-road light-duty passenger vehicles(LDPVs),and results obtained with the portable emissions measurement system(PEMS)method are particularly lacking.We developed a PEMS platform and evaluated the on-road BC emissions from ten in-use LDPVs.We demonstrated that the BC emission factors(EFs)of gasoline direction injection(GDI)engine vehicles range from 1.10 to 1.56 mg.km^(-1),which are higher than the EFs of port fuel injection(PFI)engine vehicles(0.10–0.17 mg.km^(-1))by a factor of 11.The BC emissions during the cold-start phase contributed 2%–33%to the total emissions.A strong correlation(R^(2)=0.70)was observed between the relative BC EFs and average vehicle speed,indicating that traffic congestion alleviation could effectively mitigate BC emissions.Moreover,BC and particle number(PN)emissions were linearly correlated(R^(2)=0.90),and compared to PFI engine vehicles,the instantaneous PN-to-BC emission rates of GDI engine vehicles were less sensitive to vehicle specific power-to-velocity(VSPV)increase in all speed ranges.
文摘Currently, daylighting ducts system is widely used as a daylighting device. Generally, daylighting duct system efficiently takes light from outside during the day, and conveys daylight to required location through light duct manufactured by high reflectance mirror. Daylighting duct system can convey daylight to underground space that has no windows opening to external space. Daylighting system is composed of light collection part, light guide part and light emission part. Efficiency of daylighting system is depending on type of each part used in the system. However, it is very difficult to estimate exact light flow in the system considering type of the parts. Authors performed measurement experiments to make clear the light flow with real-size model and miniature model of daylighting duct system. We discussed effect of type of the parts on efficiency of daylighting duct system.
基金Supported in part by research grants from the National Institute of Deafness and Other Communication Disorders(R01 DC 00141 and R03 DC033642)the National Institutes of Health+2 种基金the Research Fund of the American Otological Societythe Medical Research Foundation of OregonVA RR&D Center Grant RCTR-597-0160,Portland,VAMC
文摘Although stimulus frequency otoacoustic emissions (SFOAEs) have been used as a non-invasive measure of cochlear mechanics, clinical and experimental application of SFOAEs has been limited by difficulties in accurately deriving quantitative information from sound pressure measured in the ear canal. In this study, a novel signal processing method for multicomponent analysis (MCA) was used to measure the amplitude and delay of the SFOAE. This report shows the delay-frequency distribution of the SFOAE measured from the human ear. A low level acoustical suppressor near the probe tone significantly suppressed the SFOAE, strongly indicating that the SFOAE was generated at characteristic frequency locations. Information derived from this method may reveal more details of cochlear mechanics in the human ear.
文摘Non-road equipment is one of the key contributing sources to air pollution.Thus,an accurate development of emission inventory from non-road equipment is imperative for air quality management,especially for equipment with a large population such as diesel-fueled forklifts.The objective of this paper is to characterize duty-cycle based emissions from diesel-fueled forklifts using a portable emission measurement system(PEMS).Three dutycycles were defined in this study,including idling,moving,and working(active duty operation)and used to characterize in-use emissions for diesel-fueled forklifts.A total of twelve diesel-fueled forklifts were selected for real-world emission measurements.Results showed that fuel-based emission factors appear to have smaller variability compared to time-based ones.For example,the time-based emission factors for CO,HC,NO,and PM 2.5 for forklifts were estimated to be 16.6-43.9,5.3-15.1,26.2-49.9,5.5-11.1 g/hr with the fuel-based emission factors being 12.1-20.3,4.1-8.3,19.1-32.4,3.5-6.5 g/kg-fuel,respectively.NO emissions appear to be the biggest concern for emissions control.Furthermore,most of the emissions factors estimated from this study are significantly different from those in both National Guideline for Emission Inventory Development for Non-Road Equipment in China and welldeveloped emission factor models such as NONROAD by US EPA.This implies that localized,preferably fuel-based emission factors should be adjusted based on real-world emission measurements in order to develop a representative emission inventory for non-road equipment.
基金The study associated with this paper was supported by projects of China Geological Survey(DD20190085,DD20160183,1212011120976).
文摘The Sichuan Basin is one of the vital basins in China,boasting abundant hydrocarbon reservoirs.To clarify the intensity of the tectonic stress field of different tectonic episodes since the Mesozoic and to identify the regional dynamic background of different tectonic movements in the Sichuan Basin and its adjacent areas,the characteristics of the acoustic emission in rocks in different strata of these areas were researched in this paper.Meanwhile,the tectonic stress magnitude in these areas since the Mesozoic was restored.The laws state that the tectonic stress varied with depth was revealed,followed by the discussion of the influence of structural stress intensity on structural patterns in different tectonic episodes.These were conducted based on the paleostress measurement by acoustic emission method and the inversion principle of the stress fields in ancient periods and the present,as well as previous research achievements.The results of this paper demonstrate that the third episode of Yanshanian Movement(Yanshanian III)had the maximum activity intensity and tremendously influenced the structural pattern in the study area.The maximum horizontal principal stress of Yanshanian III varied with depth as follows:0.0168 x+37.001(MPa),R^2=0.8891.The regional structural fractures were mainly formed in Yanshanian III in Xujiahe Formation,west Sichuan Basin,of which the maximum paleoprincipal stress ranging from 85.1 MPa to 120.1 MPa.In addition,the law stating the present maximum horizontal principal stress varies with depth was determined to be 0.0159 x+10.221(MPa),R^2=0.7868 in Wuling Mountain area.Meanwhile,it was determined to be 0.0221 x+9.4733(MPa),R^2=0.9121 in the western part of Xuefeng Mountain area and 0.0174 x+10.247(MPa),R^2=0.8064 in the whole study area.These research results will not only provide data for the simulation of stress field,the evaluation of deformation degree,and the prediction of structural fractures,but also offer absolute geological scientific bases for the elevation of favorable shale gas preservation.
基金supported by National Natural Science Foundation of China(Nos.11175208,11275231 and 11305207)the National Magnetic Confinement Fusion Science Program of China(Nos.2012GB101001 and 2013GB112004)+1 种基金Scientific Instrument Development Project of Chinese Academy of Sciences(No.YZ200922)JSPS-NRF-NSFC A3 Foresight Program in the Field of Plasma Physics(No.11261140328)
文摘Spectroscopy in the soft X-ray and extreme ultraviolet （XEUV） region is very im- portant in magnetic fusion research. Recently, two fiat-field spectrometers that utilize a varied line spacing grating to image the spectra of 1-13 nm and 5-50 nm were installed on EAST for core impurity emission monitoring and impurity transport study. The instruments were proven to be capable of observing spectral lines from low-Z impurities （Li, C, O, N, Ar, etc.） and highly ionized medium- and high-Z impurities （Fe, Cr, Ni, Cu, Mo, etc.）. For example, spectra in the wavelength intervals of 1-2 nm and 5-13 nm contained strong metal lines~ especially molybdenum lines during H-mode phases. Argon and nitrogen lines were also observed, which were injected for diagnostic purposes. Impurity lines were identified and compared to measurements on other magnetic fusion research devices. Detailed measurements of radial emission profiles from various impurity line emissions were also presented.
基金Supported by State Key Laboratory of Engines(SKLE,200906)the National Natural Science Foundation of China(40805053)
文摘A total of 14 in-use diesel buses were selected to conduct emission measurement using a portable emissions measurement system （PEMS） in Beijing. Their instantaneous gaseous emission rates, particular matter （PM） emission rates and driving parameters were obtained. The influences of speed, acceleration and vehicle specific power （VSP） on emissions were analyzed. Based on the relationships between these driving parameters and emissions, 24 driving bins defined by speed, ac- celeration and VSP were constructed with cluster analysis to group emission rates for Euro Ⅲ and IV buses, respectively. Then the emissions reductions from Euro Ⅲ to Euro Ⅳ diesel buses were ana- lyzed. Lastly, on-road hot-stabilized emission rate model for diesel buses in Beijing was developed. Through the comparison of the model simulation emission rates with the measured emission rates, the modeled emission results were in good agreement with the measured emission results. In most of the cases, the differences were less than 12 %.
基金supported by National Natural Science Foundation of China (Nos.10675169,10735100,10727505,11005156)Major State Basic Research Developing Program of China (No.2007CB815003)
文摘The experiments of two-alpha emission from 17,18^Ne excited levels were performed at the HIRFL-RIBLL facility of the Institute of Modern Physics, Lanzhou. The beams of 17^Ne at the energy of 49.9 MeV/u and lSNe at 51.8 MeV/u bombarded a 197Au target to populate excited states of 17,18^Ne via Coulomb excitation. Complete kinematics measurements were achieved by the detectors of a silicon strip and CsI＋PIN array. The experimental results combined with simple MC simulations show the characteristic of sequential two-alpha emission via 140 excited states for lSNe. The results of two-alpha emission from 17^Ne are preliminary and need further analyses.
文摘Greenhouse gas emissions are increas- ing every year and their effect on the environment is becoming increasingly serious. In 2009, the concen- tration of carbon dioxide in the earth＇s atmosphere reached 387 μL/L, the highest level in recorded histo- ry. This paper summarizes the global carbon emission situation, sources of greenhouse gases, and the con-tribution of agriculture to the accumutauon ot green- house gases. Several scientific measures are proposed to reduce greenhouse gas emissions resulting from ru- minant production such as improving animal perform- ance, regulating the rumen environment, and reduc- ing the amount of greenhouse gases emitted from live- stock manure.
文摘Climate change is widely recognized as the major environmental problem facing the globe today. One of the most urgent environmental problems facing shipping industry is the reduction of GHG （greenhouse gas） emissions from its operations. Given the growing concern of the international community on ＂the deep reduction of global GHG emissions＂, it cannot be expected that the non-regulation of maritime GHG emissions can further continue. This paper investigates the main challenges and threats of the development of two MBMs （market-based measures） for the reduction of GHG emissions from international shipping, i.e., the ＂global levy scheme on maritime GHG emissions＂ and the ＂maritime emission trading scheme＂. A SWOT （strengths weaknesses opportunities threat） analysis is used, in this survey, to evaluate the environmental effectiveness as well as the easiness of implementation of the two policy options. Moreover, we make apparent their strengths and weaknesses concerning abatement of maritime GHG emissions. Given the fact that the discussion regarding the implementation of some MBMs with maritime GHG-emission reduction potential is still carried out with the exception of EEDI （energy efficiency design index） and SEEMP （ship energy efficiency management plan）, this paper＇s results present special significance, as they could be further analyzed and taken into account during the adoption of any future MBM for the reduction of maritime GHG emissions.
基金supported the Instantaneous Emission and Environmental Impact study on Vehicle Alternative Fuel(No.10231201902)the Project of Study and Demonstration of Real Time On-Road Vehicle Emission and Pollution Warning (No.10231201700) from the Shanghai Science and Technology Commission
文摘This study investigated the emission characteristics of ultra.fine particles based on test bench and on-board measurements. The bench test results showed the ultrafine particle number concentration of the diesel engine to be in the range of （0.56-8.35）×10^8 cm^-3. The on-board measurement results illustrated that the ultra_fine particles were strongly correlated with changes in real-world driving cycles. The particle number concentration was down to 2.0 ×10^6 cm^-3 and 2.7 ×10^7 cm^-3 under decelerating and idling operations and as high as 5.0×10^8 cm^-3 under accelerating operation. It was also indicated that the particle number measured by the two methods increased with the growth of engine load at each engine speed in both cases. The particle number presented a ＂U＂ shaped distribution with changing speed at high engine load conditions, which implies that the particle number will reach its lowest level at medium engine speeds. The particle sizes of both measurements showed single mode distributions. The peak of particle size was located at about 50-80 nm in the accumulation mode particle range. Nucleation mode particles will significantly increase at low engine load operations like idling and decelerating caused by the high concentration of unburned organic compounds.
文摘Spectral technology has become an important detection method due to its advantages such as non- intrusive measurement and on-line analysis. In this paper, two applications of spectral technology in thermal detection were proposed. First, a novel spectroscopic method based on Planck＇s law for measurement of emissivity was introduced. The emissivity, obtained by comparing the radiation intensity of the blackbody which had the same temperature as the flame with the detected intensity of the flames, could be used for on-line measurements and had a relatively higher upper tempera- ture limit. Then, a spectroscopic method for composition detection of blended fuels was proposed based on the emissivity measured. By comparing the spectra of blended fuels and single fuels, the ratio of single fuels of the blended fuel could be calculated. The measurement system proposed in this paper, which consists of a spectrometer and a computer, is very compact.
基金the support of China’s Research and Development Special Fund for Public Welfare Industry[Meteorology GYHY201206002,GYHY200906022-1,and GYHY201306077]a key project in the national science&technology pillar program during the Eleventh Five-Year Plan of China titled"Improved integrated observations of experiments to support quantitative sandstorm remote sensing and model prediction(2008BAC40B05)"a key project of the National High Technology Research and Development Program(863 Program)titled"Generation and applications of global products of essential land variables[2009AA122103-01]."。
文摘The land surface broadband emissivity (LSBE) is a key parameter for estimatingsurface radiation, and there have been many studies of the LSBE at global orlocal scales. However, few studies have validated the surface emissivity databasewith multi-point field measurement data using infrared radiometry, especially inChina. In this study, we focus on the validation of the emissivity product of theglobal land surface satellite (GLASS) LSBE database for northern China for theperiod from 2006 to 2011. Specifically, we have employed an eight-day averaged,gridded emissivity product in the 813.5 mm spectral range produced at a spatialresolution of 1000 m from the Moderate Resolution Imaging Spectrometeralbedo product using a new algorithm. The GLASS LSBE database was validatedover bare surfaces with field measurement data from sand samples collected atmany pseudo-invariant sand dune sites located in western and northwesternChina. By comparing measured emissivity for different land surface types atdifferent sites and different times, it was shown that the results were consistentand that the accuracy of the field measurements was reliable. The results of thevalidation of GLASS LSBE with these field emissivity data showed very goodagreement.
基金The Positron Imaging Centre is supported by an EPSRC platform grant, EP/F035845/1
文摘The University of Birmingham has pioneered and adapted the use of the medical imaging technique known as positron emission tomography （PET） to the study of particulate, granular and multiphase flows in industrial and physical processes, This paper provides a review of the PET and complimentary positron emission particle tracking （PEPT） techniques and details their application to the study of particulate sys- tems, The current state of the art, recent developments and example results from many of the applications to which these techniques have been applied are highlighted.
基金This work was supported by the Public Environmental Service Project of the Ministry of Environmental Protection of PRC(No.201409012)the Research Project of the Bureau of Science and Technology of Sichuan(No.2019YFS0498)。
文摘The objective of this paper is to quantify the variability in emissions of off-road equipment using a portable emission measurement system.A total of 53 commonly used equipment for agriculture,base construction,paving construction,and material handling were selected.Time-based and fuel-based emissions were quantified by different duty and engine modes.Three duty modes(idling,moving,and working)were used.Ten engine modes were defined based on normalized engine revolutions-per-minute and manifold absolute pressure,respectively.Composite emission factors taking into account both duty modes and its corresponding time percentage during a typical duty cycle were estimated.Results showed that there existed a large off-road equipment variability in emissions.Depending on duty and engine modes,time-based NO emissions ranged from 3.1 to 237.9,29.1‒1475.6,83.2‒681.6,and 3.2‒385.2 g/h for agriculture,base construction,paving construction and material handling equipment,respectively while for fuel-based NO emissions these ranges were 5.3‒52.0,11.7‒69.0,4.8‒30.8,and 11.0‒54.6 g/kg,respectively.Furthermore,emission factors derived from this study exhibited a much larger variability compared to those used in NONROAD by US EPA and National Guideline for Off-road Equipment of China.This implied that localized measurements of emissions are needed for improvement of accuracy of emission inventory.Furthermore,both equipment types and operations should be considered for development of emission inventory and control strategy.
基金Humanities and Social Science Fund of Ministry of Education of China(22YJC790008)Soft Science Research Project of Xi’an Municipal Science and Technology Bureau(22RKYJ0023)Shaanxi Province Social Science Federation Fund(2022HZ1824)。
文摘Cities generate more than 60%of carbon emissions and are the main battleground for achieving the target.However,there is no unified and standardized measurement methods of carbon emissions in cities.In this paper,we took Xi’an as an example and started by measuring carbon emissions with the new standards.Then,the decoupling of economic development from carbon emissions was studied according to the Tapio decoupling theory.Based on the generalized Divisia index method,the decoupling effort model was proposed to study the impact of carbon emission factors contributing to carbon reduction.The results show:(i)During the period 1995–2021,the carbon emissions of Xi’an increased rapidly,with an average annual growth rate of 6.06%,due to the accelerating pace of urbanization and industrialization.(ii)The energy consumption sector accounted for the largest share of carbon emissions,ranging from 77.38%to 89.46%.Xi’an’s energy structure is primarily based on fossil fuels,especially coal,which holds a significant proportion.To achieve the“double carbon”goal,it is crucial to reduce the dependence on fossil fuels.(iii)The 10th Five-Year Plan was in the state of“expansive coupling”,while other periods were in the“weak decoupling”state from the 9th to 14th Five-Year Plan periods.After the carbon peak year in the 15th Five-Year Plan,it would be in a state of“strong decoupling”.The agricultural production account was the first to achieve a“strong decoupling”state.(iv)The government of Xi’an made efforts to decouple,but these were not enough.Technological innovation played a crucial role in the carbon reduction of Xi’an,and was a key factor in achieving the“double carbon”goal.
基金supported by the Hi-Tech Research and Development Program (863) of China (No. 2009AA06Z304)the Macao Environmental Protection Bureauthe National Natural Science Foundation of China (No. 50808169),50808169)
文摘The real-world fuel efficiency and exhaust emission profiles of CO, HC and NOx for light-duty diesel vehicles were investigated. Using a portable emissions measurement system, 16 diesel taxies were tested on different roads in Macao and the data were normalized with the vehicle specific power bin method. The 11 Toyota Corolla diesel taxies have very good fuel economy of （5.9 ± 0.6） L/100 km, while other five diesel taxies showed relatively high values at （8.5 ± 1.7） L/100 km due to the variation in transmission systems and emission control strategies. Compared to similar Corolla gasoline models, the diesel cars confirmed an advantage of ca. 20% higher fuel efficiency. HC and CO emissions of all the 16 taxies are quite low, with the average at （0.05 ± 0.02） g/km and （0.38 ± 0.15） g/km, respectively. The average NOx emission factor of the 11 Corolla taxies is （0.56 ± 0.17） g/km, about three times higher than their gasoline counterparts. Two of the three Hyundai Sonata taxies, configured with exhaust gas recirculation （EGR） ＋ diesel oxidation catalyst （DOC） emission control strategies, indicated significantly higher NO2 emissions and NO2/NOx ratios than other diesel taxies and consequently trigger a concern of possibly adverse impacts on ozone pollution in urban areas with this technology combination. A clear and similar pattern for fuel consumption and for each of the three gaseous pollutant emissions with various road conditions was identified. To save energy and mitigate CO2 emissions as well as other gaseous pollutant emissions in urban area, traffic planning also needs improvement.
基金The research described in this paper is supported by the National Natural Science Foundation of China(Grant Nos.50908121 and 20521140077).
文摘Particulate pollution was a critical challenge to the promise of good air quality during the 2008 Beijing Olympic Games,which took place from August 8th to 24th.To ensure good air quality for the Games,several temporary emission control measures were implemented in Beijing and surrounding areas.Ambient particulate matter concentration decreased significantly during the Olympic period;however,it is difficult to distinguish the effectiveness of those control measures since meteorology also affects ambient PM_(2.5) concentration.In this work,a multiple linear regression model based on continuous field monitoring at a roadside site was conducted to evaluate the effects of meteorology and emission control measures on the reduction of PM_(2.5) during the 2008 Olympic Games.The hourly data set was divided into two time periods,the no control period,June 22nd to July 4th,and the control period,July 28th to August 21st.The response variable was PM_(2.5) and the meteorology covariates used in the model were hourly temperature,dew point temperature,wind speed and precipitation.Wind direction was not a significant predictor of PM_(2.5) levels in either the control or the no control period.Using the meteorologically-based regression coefficients from the two time periods,meteorology was found to contribute to at least a 16%reduction in PM_(2.5) levels in the roadside microenvironment;while the pollution control measures contributed to at least a 43%reduction in PM_(2.5) levels.
基金supported by the National Science Foundation of China (Nos. 41275124, 51278272)the Beijing Natural Science Foundation (8142011)+1 种基金the Ministry of Environmental Protection of China (No. 201209007)the International Council on Clean Transportation (ICCT) research program
文摘A database of real-world diesel vehicle emission factors, based on type and technology, has been developed following tests on more than 300 diesel vehicles in China using a portable emission measurement system. The database provides better understanding of diesel vehicle emissions under actual driving conditions. We found that although new regulations have reduced real-world emission levels of diesel trucks and buses significantly for most pollutants in China, NOx emissions have been inadequately controlled by the current standards, especially for diesel buses, because of bad driving conditions in the real world. We also compared the emission factors in the database with those calculated by emission factor models and used in inventory studies. The emission factors derived from COPERT（Computer Programmer to calculate Emissions from Road Transport） and MOBILE may both underestimate real emission factors, whereas the updated COPERT and PART5（Highway Vehicle Particulate Emission Modeling Software） models may overestimate emission factors in China. Real-world measurement results and emission factors used in recent emission inventory studies are inconsistent,which has led to inaccurate estimates of emissions from diesel trucks and buses over recent years. This suggests that emission factors derived from European or US-based models will not truly represent real-world emissions in China. Therefore, it is useful and necessary to conduct systematic real-world measurements of vehicle emissions in China in order to obtain the optimum inputs for emission inventory models.
基金supported in part by the National Natural Science Foundation of China (Grant Nos. 71901035, 51878062, and 51908462)in part by the Fundamental Research Funds for the Central Universities (Grant No. 300102210113)by the Higher Education Discipline Innovation Project 111 (Grant No. B20035)
文摘With the increasing international consensus concerning the negative effects of climate change,reducing greenhouse gases has become a higher priority in government policies and research committees.The transportation sector generates approximately 29%of the total greenhouse gas emissions and 25%of the global energy related carbon dioxide(CO2)emissions.Thus,it is essential to understand the influencing factors of vehicle emissions and establish a corresponding evaluation model for the emission estimation of operating vehicles.This paper reviews different methods of measuring vehicle emissions,including laboratory measurements,on-road measurements,and tunnel measurements.Then,we summarize the factors affecting the emission evaluation of operating vehicles based on the vehicle operating features and road environment.Finally,the applications of vehicle emission evaluation models are analyzed,including the emission assessment of the vehicles operating at road segments and intersections.Based on this review,one can conclude that selecting different measurements will significantly impact the assessment of the vehicle emission results and the applicable scope of the measurements.Considering the different influencing factors of the operating vehicle emissions will have an impact on the model application of the vehicle emission evaluation.Moreover,several analysis methods for new technology vehicles can compensate for the potential lack in connectedness with the rapid development of new energy vehicle technology and the improvement of intelligent transportation systems(ITS).
