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Le Cao   Dr.  Other 
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Le Cao published an article in October 2016.
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0 Analog Circuit
0 FDTD
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Top co-authors See all
Ulrich Platt

320 shared publications

Z. Tian

188 shared publications

Henan Agricultural University

Shen Liu

181 shared publications

Department of Orthopaedic Surgery, Shanghai Sixth People's Hospital Affiliated to Shanghai Jiaotong University, Shanghai 200233, People's Republic of China

Ping Yan

176 shared publications

Haixia Wang

157 shared publications

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Publication Record
Distribution of Articles published per year 
(2005 - 2016)
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Publications See all
Article 1 Read 0 Citations Design and experimental research for a new kind of lung function parameters measurement device Zhanshe Guo, Chao Lu, Xiangdang Liang, Ke Song, Le Cao Published: 01 October 2016
IET Science, Measurement & Technology, doi: 10.1049/iet-smt.2015.0278
DOI See at publisher website
CONFERENCE-ARTICLE 10 Reads 0 Citations Impacts of Organic Sources on the Ozone Depletion Events in Arctic Spring Zhaohuan Liu, Le Cao Published: 15 July 2016
The 1st International Electronic Conference on Atmospheric Sciences, doi: 10.3390/ecas2016-B002
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Impacts of atmospheric halogens on the ozone depletion events (ODEs) in polar boundary layer have been under investigation since the discovery of negative correlation between atmospheric ozone and bromine. By simulating an ODE in a box model KINAL, this study focuses on the influence of natural organic sources on the ozone depletion. An estimation of bromine flux from Arctic plantation is given as 6.3 x 106 molec. Br/(cm2s). Since there exists huge fluctuation in the flux, the bromine input is set to be adjustable, by which the impact of Arctic biological behavior on the tropospheric ozone can be predicted. Meanwhile, another nitrogen flux emitted from plants is also included in the model as the plants release considerable amount of nitrogen into the atmosphere, which alters the process of the ozone depletion. Different from the Br flux, the nitrogen flux implemented in the model remains relatively stable around 1 x 108 molec. NO/(cm2s). The simulation results indicate that the type of the Br flux plays a relatively important role in the depletion of ozone. An average level of Br input may cause approximately a 1.0 day antedate to the ODE. In contrast to that, NO exerts minor impact on the ozone concentration, but an obvious force to the mixing ratio of Br species.

CONFERENCE-ARTICLE 3 Reads 0 Citations Sensitivity of the Reaction Mechanism for the Ozone Depletion Events during the Arctic Spring on the Initial Atmospheric... Le Cao, Min He Published: 15 July 2016
The 1st International Electronic Conference on Atmospheric Sciences, doi: 10.3390/ecas2016-A005
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The ozone depletion events (ODEs) in the spring of Arctic has been investigated since the 1980s. It is found that the depletion of ozone is highly associated with the release of halogens especially bromine containing compounds from various substrates such as the ice/snow-covered surfaces in Arctic. In the present study, the dependence of the mixing ratios of ozone and principal bromine species during ODEs on the initial composition of the atmosphere in the boundary layer of Arctic is investigated by using a concentration sensitivity analysis, which is performed by implementing a reaction mechanism representing the ozone depletion and halogen release in a box model KINAL. The ratio between the relative change of the mixing ratios of particular species such as ozone and the variation in the initial concentration of each  atmospheric component is calculated, which reveals the relative importance of each initial species in the chemical kinetic system. The simulation results show that the impacts of various chemical species are different for ozone and bromine containing compounds during the depletion of ozone. It is found the species CH3CHO is the most influential species which critically controls the time scale of the complete removal of ozone. However, the rate of ozone depletion and the maximum values of bromine species are only slightly influenced by the presence of CH3CHO. Besides, according to the concentration sensitivity analysis, the reduction of initial Br2 is found to cause a significant retardant of the ODE while the initial mixing ratio of HBr exerts minor influence on both ozone and bromine species. In addition, it is also interesting to note that the increase of C2H2 would significantly raise the amount of HOBr and Br in the atmosphere while the ozone depletion is hardly changed.

Article 2 Reads 1 Citation Numerical Analysis of the Role of Snowpack in the Ozone Depletion Events during the Arctic Spring Le Cao, Ulrich Platt, Chenggang Wang, Qing Qin Published: 07 July 2016
Atmospheric Chemistry and Physics Discussions, doi: 10.5194/acp-2016-553
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The tropospheric ozone depletion events (ODEs) and the related enhancement of reactive bromine in the boundary layer were observed in the springtime of Arctic almost 40 years ago. It is found that various substrates in polar regions such as the snowpack are able to release bromine, which is responsible for the consumption of ozone in the boundary layer. In the present simulation, a snowpack module which represents the mass transfer between the ambient air and the snowpack is implemented in a box model, aiming to clarify the influences of the snowpack on ODEs and the associated bromine explosion in the ambient air as well as in the interstitial air of the snowpack. In the snowpack module, the processes including the deposition of bromine containing compounds onto the snowpack, the mass exchange between the snow interstitial air and snow particles, and the release of Br2 from the snowpack to the ambient air are parameterized by estimating the transfer resistances which an air parcel experiences when being transported through the boundary layer into the snowpack. The present model successfully captures the complete removal of ozone both in the boundary layer and in the snow interstitial air. The temporal and spatial distributions of bromine species such as Br2 are shown and compared with observations. By changing the properties of the snowpack, it is found that the size of snow grains, volume fraction of the liquid-like layer (LLL), and the rate of the mass exchange between the snow interstitial air and the snow particles are the critical parameters which determine the occurrence of ODEs. The simulation results show that a smaller size of the snow grains considerably accelerates the ozone depletion process. Moreover, the decrease of LLL volume fraction in snow grains is found to slow down the scavenging process of HOBr by the snow particles, which prohibits the occurrence of ODEs in the snowpack. In addition, according to the simulations with the modification of the snowpack thickness, the depletion of ozone in the ambient air is shown to be influenced more heavily by the bromine explosion occurring in the surface snow layers instead of the deep snow layers. The importance of each step in the mass transfer processes occurring between the boundary layer and the snowpack is identified by conducting a local concentration sensitivity analysis. It is shown that the snow chemistry occurring in the surface snow layers has a relatively larger impact on the depletion of ozone in the ambient air compared to that within the deep snow layers. Besides, during the period of the ozone depletion, the mixing ratio of ozone in the boundary layer is mostly influenced by the deposition of HOBr onto the surface snow layers and the release of Br2 from the snow layers close to the ground surface. In contrast to that, in the interstitial air of the surface snow layer, the uptake of HOBr by snow particles is indicated as the most dominant step for the ODE.
Article 1 Read 0 Citations Study on solving method for output signal of frequency resonant gyroscope Le Cao, Shangchun Fan, Zhanshe Guo, Cheng Li Published: 16 June 2016
Microsystem Technologies, doi: 10.1007/s00542-016-3019-8
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This paper proposed a kind of real-time online solving method based on the analog circuit for the output signal solution of frequency resonant gyroscope. This method firstly established the vibration differential equation of frequency resonant gyroscope, deduced the output signal solving model under some constraints, and used the digital simulation technology for the principle verification of solving equation. Then the verification results showed that the solving equation was feasible. Subsequently, the corresponding circuit design scheme and specific analog circuit design were given, the differential equation of this solving circuit was deduced, and the equivalent relation between the theoretically solving model and circuit differential equation was built. The experimental results showed that there existed a higher linearity between input signal and output signal of angular rate as well as that adj. R2 reached 0.99978. Hence, these experimental results verified the effectiveness of this method. Simultaneously, the analog circuit of the whole solving process was likely to provide the integrated and small solving unit in future. This solving method provided a new way to solve the efficient and real-time angular rate signal for the frequency resonant gyroscope.
Article 2 Reads 3 Citations Role of the boundary layer in the occurrence and termination of the tropospheric ozone depletion events in polar spring Le Cao, Ulrich Platt, Eva Gutheil Published: 01 May 2016
Atmospheric Environment, doi: 10.1016/j.atmosenv.2016.02.034
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Highlights•Bromine released from the underlying surface accumulates in the boundary layer, leading to the occurrence of the ozone depletion events (ODEs).•The quantitative information of the conditions under which ODEs occur, terminate and recur is given.•The transitions among severe ODEs, partial ODEs, and the full recovery of ozone are captured.•The simulation results obtained in the present model help to explain an unsolved finding in the observations of Bottenheim et al. (2009).•The termination of ODEs is found after approximately two hours. AbstractTropospheric ozone depletion events (ODEs) in the polar spring are frequently observed in a stable boundary layer condition, and the end of the events occurs when there is a breakup of the boundary layer. In order to improve the understanding of the role of the boundary layer in the ozone depletion event, a one-dimensional model is developed, focusing on the occurrence and the termination period of the ozone depletion episode. A module accounting for the vertical air transport is added to a previous box model, and a first-order parameterization is used for the estimation of the vertical distribution of the turbulent diffusivity. Simulations are performed for different strengths of temperature inversion as well as for different wind speeds. The simulation results suggest that the reactive bromine species released from the underlying surface into the lowest part of the troposphere initially stay in the boundary layer, leading to an increase of the bromine concentration. This bromine accumulation causes the ozone destruction below the top of the boundary layer. After the ozone is totally depleted, if the temperature inversion intensity decreases or the wind speed increases, the severe ozone depletion event tends to transit into a partial ozone depletion event or it recovers to the normal ozone background level of 30-40 ppb. This recovery process takes about two hours. Due to the presence of high-level HBr left from the initial occurrence of ODEs, the complete removal of ozone in the boundary layer is achieved a few days after the first termination of ODE. The time required for the recurrence of the ozone depletion in a 1000 m boundary layer is approximately 5 days, while the initial occurrence of the complete ozone consumption takes 15 days. The present model is suitable to clarify the reason for both the start and the termination of the severe ozone depletion as well as the partial ozone depletion in the observations.