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Search Results: 1 - 10 of 104301 matches for " Leiming Zhang "
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Model-Measurement Comparison of Ammonia Bi-Directional Air-Surface Exchange Fluxes over Agricultural Fields  [PDF]
Zhuanshi He, Lorraine Paige Wright, Leiming Zhang
Atmospheric and Climate Sciences (ACS) , 2013, DOI: 10.4236/acs.2013.34048

Modeled and measured bi-directional fluxes (BDFs) of ammonia (NH3) were compared over fertilized soybean and corn canopies for three intensive sampling periods: the first, during the summer of 2002 in Warsaw, North Carolina (NC), USA; and the second and third during the summer of 2007 in Lillington, NC. For the first and the third experimental periods, the BDF model produced reasonable diurnal flux patterns. The model also produced correct flux directions (emission and dry deposition) and magnitudes under dry and wet canopy conditions and during day and nighttime for these two periods. However, the model fails to produce the observed very high upward fluxes from the second sampling period due to the fertilization application (and thus being much higher soil emission potentials in the field than the default model values), although this can be improved by adjusting model input of soil emission potentials. Model-measurement comparison results suggest that the model is likely capable for improving long-term or regional scale ammonia predictions if implemented in chemical transport models replace the traditional dry

Cloud Processing of Gases and Aerosols in Air?Quality Modeling
Wanmin Gong,Craig Stroud,Leiming Zhang
Atmosphere , 2011, DOI: 10.3390/atmos2040567
Abstract: The representations of cloud processing of gases and aerosols in some of the current state-of-the-art regional air quality models in North America and Europe are reviewed. Key processes reviewed include aerosol activation (or nucleation scavenging of aerosols), aqueous-phase chemistry, and wet deposition/removal of atmospheric tracers. It was found that models vary considerably in the parameterizations or algorithms used in representing these processes. As an emerging area of research, the current understanding of the uptake of water soluble organics by cloud droplets and the potential aqueous-phase reaction pathways leading to the atmospheric secondary organic aerosol (SOA) formation is also reviewed. Sensitivity tests using the AURAMS model have been conducted in order to assess the impact on modeled regional particulate matter (PM) from: (1) the different aerosol activation schemes, (2) the different below-cloud particle scavenging algorithms, and (3) the inclusion of cloud processing of water soluble organics as a potential pathway for the formation of atmospheric SOA. It was found that the modeled droplet number concentrations and ambient PM size distributions were strongly affected by the use of different aerosol activation schemes. The impact on the modeled average ambient PM mass concentration was found to be limited in terms of averaged PM 2.5 concentration (~a few percents) but more significant in terms of PM 1.0 (up to 10 percents). The modeled ambient PM was found to be moderately sensitive to the below-cloud particle scavenging algorithms, with relative differences up to 10% and 20% in terms of PM 2.5 and PM 10, respectively, when using the two different algorithms for the scavenging coefficient (Λ) corresponding to the lower and upper bounds in the parameterization for Λ. The model simulation with the additional cloud uptake and processing of water-soluble organic gases was shown to improve the evaluation statistics for modeled PM 2.5 OA compared to the IMPROVE network data, and it was demonstrated that the cloud processing of water-soluble organics can indeed be an important mechanism in addition to the traditional secondary organic gas uptake to the particle organic phase.
A kind of coccoid dinoflagellates-like fossils gives a new explanation of source of dinosterane in the Early-Middle Cambrian
Lizeng Bian,Shuichang Zhang,Baomin Zhang,Shaozhi Mao,Leiming Yin
Chinese Science Bulletin , 2001, DOI: 10.1007/BF03183280
Abstract: The coccoid fossils covered with thick gelatinous envelop containing several gametes are discovered in gyps and salt deposits of Cambrian, H4well and chert bed of the base of Yuertus Formation (∈ 1 1 ) of Xiaoerbulake Section. The fossils are described and compared with coccoid dinoflagellates. These fossils may be a coccoid life-cycle stage (vegetative cyst) of coccoid dinoflagellates. If this identification is correct, the coccoid dinoflagellates-like fossils could give a reasonable explanation of the dinoflagellate-specific biomarkers from Cambrian, H4 well, Tarim Basin.

Li Leiming,Zhang Zhiyi,

生物物理学报 , 1996,
Abstract: The photoinduced bacteriostasis effect of ZnS colloid was studied with using growth rate method. It was observed that ZnS colloid can inhibit the growth of Verticillium Dahliae obvisouly under irradiation, but it loses this fuction in dark. The reason may be a great amount of active oxygen was generated when ZnS was actived by light. In the condition of this article, the medium lethal concentration(LC50) of ZnS colloid is 4. 33×10-5mol/L.
Characteristics of sea surface fluxes on nonstationary synoptic systems

Miao Manqian,Zhang Leiming,

大气科学 , 1990,
Abstract: 本文研究了天气尺度系统(如冷锋)过境时的海面通量特征及计算通量的方法。发现冷锋前几小时的暖区内,湍流切应力急剧增大,总体输送系数 C_D,C_H出现突变,与地面风速的突然增加是同步的。这是地转适应过程在边界层内的一种响应,为海面上动力学过程的研究提供了重要信息。
Numerical Simulation of Planetary Boundary Layer When Cold-air Outbreaks Over Land

Zhang Leiming,Zhao Ming,

大气科学 , 1993,
Abstract: A three dimensional numerical meso-scale model was developed to simulate cold-air outbreak processes over underlying surface with plain and regular terrain. The weather change processes without the cold-air were also simulated for comparison. The result show reasonable phenomena, such as strong wind , the change of wind direction , the abrupt increase of the momentum flux and pressure , ect.
A Differential Feedback Scheme Exploiting the Temporal and Spectral Correlation
Mingxin Zhou,Leiming Zhang,Lingyang Song,Merouane Debbah
Computer Science , 2013,
Abstract: Channel state information (CSI) provided by limited feedback channel can be utilized to increase the system throughput. However, in multiple input multiple output (MIMO) systems, the signaling overhead realizing this CSI feedback can be quite large, while the capacity of the uplink feedback channel is typically limited. Hence, it is crucial to reduce the amount of feedback bits. Prior work on limited feedback compression commonly adopted the block fading channel model where only temporal or spectral correlation in wireless channel is considered. In this paper, we propose a differential feedback scheme with full use of the temporal and spectral correlations to reduce the feedback load. Then, the minimal differential feedback rate over MIMO doubly selective fading channel is investigated. Finally, the analysis is verified by simulations.
苗曼倩 Miao Manqian,张雷鸣 Zhang Leiming
大气科学 , 1990, DOI: 10.3878/j.issn.1006-9895.1990.04.09
Abstract: 本文研究了天气尺度系统(如冷锋)过境时的海面通量特征及计算通量的方法。发现冷锋前几小时的暖区内,湍流切应力急剧增大,总体输送系数C_D,C_H出现突变,与地面风速的突然增加是同步的。这是地转适应过程在边界层内的一种响应,为海面上动力学过程的研究提供了重要信息。
张雷鸣 Zhang Leiming,赵鸣 Zhao Ming
大气科学 , 1993, DOI: 10.3878/j.issn.1006-9895.1993.02.14
Abstract: 本文建立了一个三维中尺度模式,分别模拟了平坦地形及规则山地情形下冷空气爆发过程,并模拟了无冷空气时天气演变过程作为比较.模拟结果合理地给出了冷空气爆发后边界层内诸要素的变化规律,如大风的出现、风向的改变、动量通量的增大、气压的升高等.
Electron and phonon correlations in systems of one-dimensional electrons coupled to phonons
Leiming Chen
Physics , 2008, DOI: 10.1103/PhysRevB.78.195119
Abstract: Electron and phonon correlations in systems of one-dimensional electrons coupled to phonons are studied at low temperatures by emphasizing on the effect of electron-phonon backward scattering. It is found that the $2k_F$-wave components of the electron density and phonon displacement field share the same correlations. Both correlations are quasi-long-ranged for a single conducting chain coupled to one-dimensional or three-dimensional phonons, and they are long-ranged for repulsive electron-electron interactions for a three-dimensional array of parallel one-dimensional conducting chains coupled to three-dimensional phonons.
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