Macro-and Micro-physical Characteristics of Different Parts of Mixed Convective-stratiform Clouds and Differences in Their Responses to Seeding

This study investigates the cloud macro-and micro-physical characteristics in the convective and stratiform regions and their different responses to the seeding for mixed convective-stratiform clouds that occurred in Shandong province on 21 May 2018,based on the observations from the aircraft,the Suomi National Polar-Orbiting Partnership(NPP)satellite,and the high-resolution Himawari-8(H8)satellite.The aircraft observations show that convection was deeper and radar echoes were significantly enhanced with higher tops in response to seeding in the convective region.This is linked with the conversion of supercooled liquid droplets to ice crystals with released latent heat,resulting in strengthened updrafts,enhanced radar echoes,higher cloud tops,and more and larger precipitation particles.In contrast,in the stratiform cloud region,after the Silver Iodide(AgI)seeding,the radar echoes become significantly weaker at heights close to the seeding layer,with the echo tops lowered by 1.4–1.7 km.In addition,a hollow structure appears at the height of 6.2–7.8 km with a depth of about 1.6 km and a diameter of about 5.5 km,and features such as icing seeding tracks appear.These suggest that the transformation between droplets and ice particles was accelerated by the seeding in the stratiform part.The NPP and H8 satellites also show that convective activity was stronger in the convective region after seeding;while in the stratiform region,a cloud seeding track with a width of 1–3 km appears 10 km downstream of the seeding layer 15 minutes after the AgI seeding,which moves along the wind direction as width increases.

Comparison of Cloud Properties between Cloud Sat Retrievals and Airplane Measurements in Mixed-Phase Cloud Layers of Weak Convective and Stratus Clouds

Cloud microphysical properties including liquid and ice particle number concentration （NC）, liquid water content （LWC）, ice water content （IWC） and effective radius （RE） were retrieved from CloudSat data for a weakly convective and a widespread stratus cloud. Within the mixed-phase cloud layers, liquid-phase fractions needed to be assumed in the data retrieval process, and one existing linear （Pl） and two exponential （P2 and P3） functions, which estimate the liquid-phase fraction as a function of subfreezing temperature （from -20℃ to 0℃）, were tested. The retrieved NC, LWC, IWC and RE using Pl were on average larger than airplane measurements in the same cloud layer, Function P2 performed better than p1 or P3 in retrieving the NCs of cloud droplets in the convective cloud, while function Pl performed better in the stratus cloud. Function P3 performed better in LWC estimation in both convective and stratus clouds. The REs of cloud droplets calculated using the retrieved cloud droplet NC and LWC were closer to the values of in situ observations than those retrieved directly using the Pl function. The retrieved NCs of ice particles in both convective and stratus clouds, on the assumption of liquid-phase fraction during the retrieval of liquid droplet NCs, were closer to those of airplane observations than on the assumption of function P1.

Thermodynamic Feedback between Clouds and the Ocean Surface Mixed Layer

A cloud-ocean planetary boundary layer (OPBL) feedback mechanism is presented and tested in this paper. Water vapor, evaporated from the ocean surface or transported by the large-scale air flow, often forms convective clouds under a conditionally unstable lapse rate. The variable cloud cover and rainfall may have positive and negative feedback with the ocean mixed layer temperature and salinity structure. The coupling of the simplified Kuo's (1965) cumulus cloud model to the Kraus-Turner's (1967) ocean mixed layer model shows the existence of this feedback mechanism. The theory also predicts the generation of low frequency oscillation in the atmosphere and oceans.

Further Laboratory Experiments on Aerosol Scavenging in Mixed Clouds to Assess the Role of Phoretic Forces and Particle Solubility

Scavenging experiments have been performed in a cloud chamber inside a cold room with different aerosol particles: Paraffin particles, NaCl particles, Magnesium oxide particles, Carbon particles, Sahara dust particles. Essentially the experimental tests were carried on following the sequence of operations: the generation of the aerosol particles, their injection in the lower part of the cloud chamber, injection of water droplets in the whole chamber volume, nucleation of ice crystals, collection of ice crystals and their examination as for resulting scavenging efficiency. Evidence is given of the peculiar behaviour of soluble particles, individual and eventually inside mixed particles, leading to very much important scavenging efficiency, probably to be ascribed to aerodynamic capture. The evident peculiar behaviour of deliquescent particles can be oriented towards applications to an efficient abatement of specific effluents, on one side, and to weather modification experiments, both rain enhancement and hail prevention experiments.

Case Analysis on Physical Characteristics of Autumn Cumulus-stratus Mixed Cloud in Shandong Province

[Objective] The aim was to analyze physical structures of mixed cloud in autumn in Shandong.[Method] By dint of Doppler radar data,the raindrop spectrum data observed by laser spectrometer,second sounding data of L-band,satellite retrieval data,and other general information,the physical structures of mixed cloud in autumn on August 29,2009 were discussed.[Result] This was a typical precipitation process of mixed cloud,and the main precipitation process lasted for 10 hours.Rainfall intensity was ups and downs obviously with the time.The maximum rainfall intensity was 6.5 mm/h and the normal of that was less than 3.0 mm/h.The rain concentrations were between 5 and 300,and the raindrop spectrum was mainly of bimodal or multimodal peaks.It showed that the precipitating cloud was mainly cold cloud and the development of warm layers was not well according to the vertical structure of clouds which was analyzed by second sounding data.It showed by the Doppler radar data that the whole precipitation process was divided into four stages:prior period and initial,maturing,declining stages for precipitation,which the echo structure of different stages was quite different.[Conclusion] The study laid theoretical basis for the study on precipitation mechanism and artificial precipitation potential.

Evaluation and Optimization of the Mixed Redundancy Strategy in Cloud-Based Systems

Mixed redundancy strategies are generally used in cloud-based systems,with different node switch mechanisms from traditional fault-tolerant strategies.Existing studies often concentrate on optimizing a single strategy in cloud computing environment and ignore the impact of mixed redundancy strategies.Therefore,a model is proposed to evaluate and optimize the reliability and performance of cloud-based degraded systems subject to a mixed active and cold standby redundancy strategy.In this strategy,node switching is triggered by a continual monitoring and detection mechanism when active nodes fail.To evaluate the transient availability and the expected job completion rate of systems with such kind of strategy,a continuous-time Markov chain model is built on the state transition process and a numerical method is used to solve the model.To choose the optimal redundancy for the mixed strategy under system constraints,a greedy search algorithm is proposed after sensitivity analysis.Illustrative examples were presented to explain the process of calculating the transient probability of each system state and in turn,the availability and performance of the whole system.It was shown that the near-optimal redundancy solution could be obtained using the optimizationmethod.The comparison with optimization of the traditional mixed redundancy strategy proved that the system behavior was different using different kinds of mixed strategies and less redundancy was assigned for the new type of mixed strategy under the same system constraint.

Comparison of Aerosol Effects on Simulated Spring and Summer Hailstorm Clouds

Numerical simulations are carried out to investigate the effect of cloud condensation nuclei（CCN） concentrations on microphysical processes and precipitation characteristics of hailstorms. Two hailstorm cases are simulated, a spring case and a summer case, in a semiarid region of northern China, with the Regional Atmospheric Modeling System. The results are used to investigate the differences and similarities of the CCN effects between spring and summer hailstorms. The similarities are：（1） The total hydrometeor mixing ratio decreases, while the total ice-phase mixing ratio enhances, with increasing CCN concentration;（2） Enhancement of the CCN concentration results in the production of a greater amount of small-sized hydrometeor particles, but a lessening of large-sized hydrometeor particles;（3） As the CCN concentration increases, the supercooled cloud water and rainwater make a lesser contribution to hail, while the ice-phase hydrometeors take on active roles in the growth of hail;（4） When the CCN concentration increases, the amount of total precipitation lessens,while the role played by liquid-phase rainfall in the amount of total precipitation reduces, relatively, compared to that of icephase precipitation. The differences between the two storms include：（1） An increase in the CCN concentration tends to reduce pristine ice mixing ratios in the spring case but enhance them in the summer case;（2） Ice-phase hydrometeor particles contribute more to hail growth in the spring case, while liquid water contributes more in the summer case;（3） An increase in the CCN concentration has different effects on surface hail precipitation in different seasons.

体育院校大学英语混合教学模式研究

在新时代背景下,大学英语教学飞速发展。体育院校大学英语教师利用先进的教学平台和丰富的网络资源,在线上线下混合式教学方面另辟蹊径。从如何提升体育院校大学英语课程教学效果出发,在教学目标确立、教学理念更新、教学内容选择与设计、课程教学方法创新等方面对大学英语混合式教学进行了认真梳理与分析,旨在为体育院校大学英语教学改革与实践提供借鉴,进而为社会培养更多具有全方位知识体系的体育人才。

基于多重混合博弈的云储能市场优化运行策略

针对多个分布式储能主体参与云储能市场的利益分配不均问题,提出了一种基于多重混合博弈的多目标云储能优化运行策略。策略打破了传统的租赁储能资源模式,以合同方式将管理权与使用权全权交由云储能聚合商来统一协调管理。采用多重混合博弈的方法建立了考虑低碳经济的多目标优化数学模型,在保证供能需求得到满足的同时,得到了最高合作超量下的最优分配方案。仿真结果表明,相比于目前常用的研究方法,所提出方法在经济效益上提升了18.625%,碳排放量减少了5.57%,为云储能市场的发展提供了理论支持。

基于互Box-Cox变换和Markov链风速云模型的发电系统充裕度评估

为准确计及风速随机性和自相关性对风电并网系统充裕度的影响,建立基于互Box-Cox变换和Markov链的风速云模型,并将该模型与时序Monte Carlo模拟法结合,提出计及风速随机性和自相关性的风电并网系统充裕度评估方法。仿真结果表明,所提模型产生的仿真风速样本与实测风速样本具备相似的概率分布特性和自相关性,所提方法可较精确地评估风电并网系统充裕度及风电容量可信度。

基于蓝墨云班课的功能性训练混合式“金课”教学模式设计研究

该文运用文献资料法、逻辑分析法,在“互联网+”赋能发展的时代背景下,积极探索“金课”课程教学模式。基于蓝墨云班课教学平台的优势,依托蓝墨云班课软件,结合教学环境、教师活动、学生活动三大板块,对课前、课中、课后3个阶段进行深入研究,以精心设计功能性训练混合式“金课”教学模式,旨在最大化改善课堂教学效果,从而全面提升课程教学质量水平。

Observational Diagnosis of Cloud Phase in the Winter Antarctic Atmosphere for Parameterizations in Climate Models

The cloud phase composition of cold clouds in the Antarctic atmosphere is explored using data from the Moderate Resolution Imaging Spectroradiometer （MODIS） and Cloud-Aerosol Lidar with Orthogonal Polarization （CALIOP） instruments for the period 2000-2006. We used the averaged fraction of liquid-phase clouds out of the total cloud amount at the cloud tops since the value is comparable in the two measurements. MODIS data for the winter months （June, July, and August） reveal liquid cloud fraction out of the total cloud amount significantly decreases with decreasing cloud-top temperature below 0°C. In addition, the CALIOP vertical profiles show that below the ice clouds, low-lying liquid clouds are distributed over ～20% of the area. With increasing latitude, the liquid cloud fraction decreases as a function of the local temperature. The MODIS-observed relation between the cloud-top liquid fraction and cloud-top temperature is then applied to evaluate the cloud phase parameterization in climate models, in which condensed cloud water is repartitioned between liquid water and ice on the basis of the grid point temperature. It is found that models assuming overly high cut-offs （ -40°C） for the separation of ice clouds from mixed-phase clouds may significantly underestimate the liquid cloud fraction in the winter Antarctic atmosphere. Correction of the bias in the liquid cloud fraction would serve to reduce the large uncertainty in cloud radiative effects.

NUMERICAL SIMULATION OF CLOUD MICROPHYSICAL CHARACTERISTICS OF LANDFALL TYPHOON KROSA

In this study,the super typhoon KROSA(2007)was simulated using a mesoscale numerical model Global and Regional Assimilation and Prediction System(GRAPES)with a two-moment mixed-phase microphysics scheme.Local rainfall observations,radar and satellite data were also used to analyze the precipitation structure and microphysical features.It was shown that low-level jets and unstable temperature stratification provided this precipitation process with favorable weather condition.Heavy rainfall centers were located in the north and east part of KROSA with the maxima of 6-hourly total rainfall during the simulation more than 100 mm.The quantities of column solid water and column liquid water were generally equivalent,indicating the important role of ice phase in precipitation formation.Results of CloudSat showed that strong convection occurred in the eyewall around the cyclonic center.According to the simulation results,heavy precipitation in the northeast part of the typhoon was mainly triggered by convective clouds,accompanied by the strongest updraft under the melting level.In the southwest part of KROSA,precipitation intensity was rather homogeneous.The ascending center occurred in high-level cold clouds,favoring the formation and growth of ice particles.

Visualization of flatness pattern recognition based on T-S cloud inference network

Flatness pattern recognition is the key of the flatness control. The accuracy of the present flatness pattern recognition is limited and the shape defects cannot be reflected intuitively. In order to improve it, a novel method via T-S cloud inference network optimized by genetic algorithm(GA) is proposed. T-S cloud inference network is constructed with T-S fuzzy neural network and the cloud model. So, the rapid of fuzzy logic and the uncertainty of cloud model for processing data are both taken into account. What's more, GA possesses good parallel design structure and global optimization characteristics. Compared with the simulation recognition results of traditional BP Algorithm, GA is more accurate and effective. Moreover, virtual reality technology is introduced into the field of shape control by Lab VIEW, MATLAB mixed programming. And virtual flatness pattern recognition interface is designed.Therefore, the data of engineering analysis and the actual model are combined with each other, and the shape defects could be seen more lively and intuitively.

Relationships between Cloud Droplet Spectral Relative Dispersion and Entrainment Rate and Their Impacting Factors

Cloud microphysical properties are significantly affected by entrainment and mixing processes.However,it is unclear how the entrainment rate affects the relative dispersion of cloud droplet size distribution.Previously,the relationship between relative dispersion and entrainment rate was found to be positive or negative.To reconcile the contrasting relationships,the Explicit Mixing Parcel Model is used to determine the underlying mechanisms.When evaporation is dominated by small droplets,and the entrained environmental air is further saturated during mixing,the relationship is negative.However,when the evaporation of big droplets is dominant,the relationship is positive.Whether or not the cloud condensation nuclei are considered in the entrained environmental air is a key factor as condensation on the entrained condensation nuclei is the main source of small droplets.However,if cloud condensation nuclei are not entrained,the relationship is positive.If cloud condensation nuclei are entrained,the relationship is dependent on many other factors.High values of vertical velocity,relative humidity of environmental air,and liquid water content,and low values of droplet number concentration,are more likely to cause the negative relationship since new saturation is easier to achieve by evaporation of small droplets.Further,the signs of the relationship are not strongly affected by the turbulence dissipation rate,but the higher dissipation rate causes the positive relationship to be more significant for a larger entrainment rate.A conceptual model is proposed to reconcile the contrasting relationships.This work enhances the understanding of relative dispersion and lays a foundation for the quantification of entrainment-mixing mechanisms.

Moving Multiple Curves/Surfaces Approximation of Mixed Point Clouds

We propose a local model called moving multiple curves/surfaces approximation to separate mixed scanning points received from a thin-wall object,where data from two sides of the object may be mixed due to measurement error.The cases of two curves(including plane curves and space curves)and two surfaces in one model are mainly elaborated,and a lot of examples are tested.

改进的Mix&Slice算法:对称密码在云存储的应用

对数据进行加密是保证合法用户对数据访问控制的一种有效方式,基于对称密码的访问控制模型具有较高的效率和安全性.2016年的CCS会议上学者提出了一种基于对称密码的Mix&Slice算法,用于解决云端加密数据高效的权限撤销问题.算法的主要思路是在密文的每一比特充分混淆的基础上,对密文的一小部分比特重新加密.由于密文充分混淆,一小部分的缺失将导致整个密文不能解密,以此实现对数据的权限控制.本文聚焦于Mix&Slice算法的安全性及部署场景,发现其初始向量的使用不当可导致数据泄露.通过分析不同的基础加密模式对Mix&Slice算法安全性的影响,给出算法初始向量装载的两种改进方法,使其更适合实际使用场景.实验验证在提高算法安全强度的同时,本文的两种改进没有带来效率损失.

基于多尺度特征融合和残差混合注意力的点云配准算法

为提高点云配准的精度、鲁棒性和迁移性,提出一种基于多尺度特征融合和残差混合注意力的点云配准算法。计算点云中不同尺度的k邻近图,分别进行不同深度的边卷积提取特征并融合为新特征,使用具有残差结构的混合注意力模块增强有效特征,通过Transformer和软指针预测变换后的点云,用可微的奇异值分解求解刚性变换。在ModelNet40数据集进行实验,其结果表明,所提算法在干净、有噪声、未见过的点云数据上的配准结果精度更高,噪声鲁棒性更强,迁移性更好,优于对比点云配准算法。

基于编码特征学习的3D点云语义分割网络

目前点云语义分割已广泛应用到自动驾驶、虚拟现实等多个领域,但现阶段点云分割算法无法提取较完整的空间结构信息,难以解释每个点编码信息的问题.针对此缺陷,文中提出基于编码特征学习的3D点云语义分割网络.首先,在引入角度信息和增强特征的基础上构造局部特征编码器(Local Feature Encoder,LFE),学习较完整的局部空间结构,缓解相似物体错分割问题.然后,设计混合池化聚合模块(Mixed Pooling Polymerization,MPP),聚合粗犷特征和精细特征,同时保证点云的排序不变性.最后,采用多尺度特征融合,充分利用编码层不同尺度特征,实现准确的语义分割.在两个大型基准数据集S3DIS和SemanticKITTI上的实验表明文中网络的优越性.

基于云课堂的混合式教学模式在急危重症护理学中的应用

探讨基于云课堂的混合式教学模式在急危重症护理学教学中的应用,以培养学生的自主学习能力,激发其学习热情和兴趣,提升考试成绩。