Storm-scale ensemble forecast based on breeding of growth modes

How to obtain fast-growth errors, which is comparable to the actual forecast growth error, is a crucial problem in ensemble forecast （EF）. The method, Breeding of Growth Modes （BGM）, which has been used to generate perturbations for medium-range EF at NCEP, simulates the development of fast-growth errors in the analysis cycle, and is a reasonable choice in capturing growing errors modes, especially for extreme weather by BGM. An ideal supercell storm, simulated by Weather Research Forecast model （WRF）, occurred in central Oklahoma on 20 May 1977. This simulation was used to study the application of BGM methods in the meso-scale strong convective Ensemble Prediction System （EPS）. We compared the forecasting skills of EPS by different pertubation methods, like Monte-Carlo and BGM. The results show that the ensemble average forecast based on Monte-Carlo with statistics meaning is superior to the single-deterministic prediction, but a less dynamic process of the method leads to a smaller spread than expected. The fast-growth errors of BGM are comparable to the actual short-range forecast error and a more appropriate ensemble spread. Considering evaluation indexes and scores, the forecast skills of EPS by BGM is higher than Monte-Carlo＇s. Furthermore, various breeding cycles have different effects on precipitation and non-precipitation fields, confirmation of reasonable cycles need consider balance between variables.

A shortcut for determining growth mode

Thin and thick films of iron phthalocyanine （FePc） molecules are deposited on a Ag （110） surface. The nature of the FePc growth and the interaction with the substrate have been studied by X-ray photoelectron spectroscopy （XPS）. All of the core level spectra exhibit rigid shifts towards lower binding energies following the deposition of the organic films, each by a different magnitude. A greater change and a larger shift in the Fe2p level as compared to Cls core level reveals that the adsorbate interacts with the substrate mainly via the Fe atom, located at the center of the molecule. An increase/decrease in the intensity of C1 s/Ag3d level is found to be exponentially linked to the overlayer molecular coverage. Finally, the so- called growth/decay curve indicates that FePc thin films initially develop following the FM growth mode and then transform to SK mode, resulting in 3D island aggregation.

Simulation of multilayer homoepitaxial growth on Cu （100） surface

The processes of multilayer thin Cu films grown on Cu （100） surfaces at elevated temperature （250-400K） are simulated by mean of kinetic Monte Carlo （KMC） method, where the realistic growth model and physical parameters are used. The effects of small island （dimer and trimer） diffusion, edge diffusion along the islands, exchange of the adatom with an atom in the existing island, as well as mass transport between interlayers are included in the simulation model. Emphasis is placed on revealing the influence of the Ehrlic-Schwoebel （ES） barrier on growth mode and morphology during multilayer thin film growth. We present numerical evidence that the ES barrier does exist for the Cu/Cu（100） system and an ES barrier EB 〉 0.125eV is estimated from a comparison of the KMC simulation with the realistic experimental images. The transitions of growth modes with growth conditions and the influence of exchange barrier on growth mode are also investigated.

The Altun Fault: Its Geometry, Nature and Mode of Growth

The Altun (or Altyn Tagh) fault displays a geometry of overlapping of linear and arcuate segments and shows strong inhomogeneity in time and space. It is a gigantic fault system with complex mechanical behaviours including thrusting, sinistral strike slip and normal slip. The strike slip and normal slip mainly occurred in the Cretaceous—Cenozoic and Plio-Quaternary respectively, whereas the thrusting was a deformation event that has played a dominant role since the late Palaeozoic (for a duration of about 305 Ma). The formation of the Altun fault was related to strong inhomogeneous deformation of the massifs on its two sides (in the hinterland of the Altun Mountains contractional deformation predominated and in the Qilian massif thrust propagation was dominant). The fault experienced a dynamic process of successive break-up and connection of its segments and gradual propagation, which was synchronous with the development of an overstep thrust sequence in the Qilian massif and the uplift of the Qinghai-Tibet plateau. With southward propagation of the thrust sequence and continued uplift of the plateau, the NE tip of the Altun fault moved in a NE direction, while the SW tip grew in a SW direction.

Relationship between the spatial position of the seed and growth mode for single-crystal diamond grown with an enclosed-type holder

The relationship between the spatial position of the diamond seed and growth mode is investigated with an enclosedtype holder for single-crystal diamond growth using the microwave plasma chemical vapor deposition epitaxial method.The results demonstrate that there are three main regions by varying the spatial position of the seed.Due to the plasma concentration occurring at the seed edge,a larger depth is beneficial to transfer the plasma to the holder surface and suppress the polycrystalline diamond rim around the seed edge.However,the plasma density at the edge decreases drastically when the depth is too large,resulting in the growth of a vicinal grain plane and the reduction of surface area.By adopting an appropriate spatial location,the size of single-crystal diamond can be increased from 7 mm×7 mm×0.35 mm to8.6 mm×8.6 mm×2.8 mm without the polycrystalline diamond rim.

Growth rate of peeling mode in the near separatrix region of diverted tokamak plasma

An analytical expression of the peeling mode in the near separatrix region of diverted tokamak plasma is derived. It is shown that in diverted plasmas both with single and double X points, though the perturbed potential energy of the unstable peeling mode tends to be large, its growth rate becomes very small due to the even larger kinetic energy. Compared to some recent studies that give qualitatively correct results about this growth rate, our result is directly related with the diverted equilibrium quantities suitable for application to realistic experiments.

Transition of Growth Mode in Homoepitaxy on Metal Surface

The process of the multilayer growth of Pt on Pt(111)is studied by using a Monte Carlo model with realisticphysical parameters.The effects of the substrate temperature,the ES barrier,and the deposition rate on the growthmode have been investigated.Gradual transitions of the surface roughness from oscillatory to non-oscillatory behaviorand then back to oscillatory behavior are observed while increasing the substrate temperature from 270 K to 620 K.Itis found that the growth mode depends strongly on ES barrier over the whole temperatures and the deposition rate ofatoms effectively affects the growth mode.The simulation results are consistent with many experimental observationsfor homoexpitaxy on a Pt(111)substrate.

GROWTH MODE AND MODIFICATION OF GRAPHITE IN CAST IRON MELT

Using liquid quenching technique,the change of growth mode of graphite in cast iron melt was analysed.Based on the interface structure theory of crystal growth,the concept of multiplication of spiral growth steps was advanced and two basic multiplication models were given.It was proposed that multiplication of spiral steps is responsible for the change of growth mode of graphite in cast iron melt.The modifying elements such as Ce promote multiplication of spiral steps,which is regarded as the core of modification.Origination of screw dislocation and branch of the sector blocks in radius direction,both of which are essential to spheroidization of graphite in the melt,are caused by multiplication of spiral steps:and so is thickening of graphite plates.

Growth and characterization of AlN epilayers using pulsed metal organic chemical vapor deposition

We report the growth of Al N epilayers on c-plane sapphire substrates by pulsed metal organic chemical vapor deposition（MOCVD）. The sources of trimethylaluminium（TMAl） and ammonia were pulse introduced into the reactor to avoid the occurrence of the parasitic reaction. Through adjusting the duty cycle ratio of TMAl to ammonia from 0.8 to 3.0, the growth rate of Al N epilayers could be controlled in the range of 0.24 m/h to 0.93 m/h. The high-resolution x-ray diffraction（HRXRD） measurement showed that the full width at half maximum（FWHM） of the（0002） and（10-12） reflections for a sample would be 194 arcsec and 421 arcsec, respectively. The step-flow growth mode was observed in the sample with the atomic level flat surface steps, in which a root-mean-square（RMS） roughness was lower to 0.2 nm as tested by atomic force microscope（AFM）. The growth process of Al N epilayers was discussed in terms of crystalline quality, surface morphology,and residual stress.

Effect of different catalysts and growth temperature on the photoluminescence properties of zinc silicate nanostructures grown via vapor-liquid-solid method

We explore the photoluminescence properties of zinc silicate(Zn_(2)SiO_(4)) nanostructures synthesized by vapor-liquidsolid(VLS)mode of growth using three different catalysts(Sn,Ag,and Mn).Different catalysts significantly influence the growth rate which in turn has an impact on the structure and hence the photoluminescence of the prepared zinc silicate nanostructures.Zn_(2)SiO_(4) has a wide bandgap of about 5.5 eV and in its pure form,it does not emit in visible region due to its inner shell electronic transitions between the 3 d5 energy levels.However,the incorporation of different catalysts(Sn,Ag and Mn)at different growth temperatures into the Zn_(2)SiO_(4) crystal growth kinetics provides wide visible spectral range of photoluminescence(PL)emissions.PL analysis shows broad multi-band spectrum in the visible region and distinct colors(red,yellow,green,blue,cyan and violet)are obtained depending on the crystalline structure of the prepared nanostructures.The allowed transitions due to the effect of different catalysts on zinc silicate lattice offer a huge cross-section of absorption that generates strong photoluminescence.The correlation between the structural and optical properties of the synthesized nanostructures is discussed in detail.The synthesized photoluminescent nanostructures have potential applications in solidstate lighting and display devices.

Transformation of the Growth Mode:What Must Be Changed?

That the Chinese economy has been burgeoning for nearly 30 years is an irrefutable fact.However,this robust growth has been achieved amidst accusations of"extensive"development and"low-efficiency".Many scholars believe that low-priced labour is pivotal to China’s rapid growth.Even so,we find it hard to explain why China has been able to achieve sustained growth while so many countries with even lower labour costs remain trapped in poverty The following article offers a new perspective upon this paradox.

Step-edge-guided nucleation and growth mode transition of α-Ga_(2)O_(3) heteroepitaxy on vicinal sapphire

Controlling the epitaxial growth mode of semiconductor layers is crucial for optimizing material properties and device performance.In this work,the growth mode ofα-Ga_(2)O_(3) heteroepitaxial layers was modulated by tuning miscut angles(θ)from 0°to 7°off the(1010)direction of sapphire(0002)substrate.On flat sapphire surfaces,the growth undergoes a typical three-dimensional(3D)growth mode due to the random nucleation on wide substrate terraces,as evidenced by the hillock morphology and high dislocation densities.As the miscut angle increases toθ=5°,the terrace width of sapphire substrate is comparable to the distance between neighboring nuclei,and consequently,the nucleation is guided by terrace edges,which energetically facilitates the growth mode transition into the desirable two-dimensional(2D)coherent growth.Consequently,the mean surface roughness decreases to only 0.62 nm,accompanied by a significant reduction in screw and edge dislocations to 0.16×10^(7) cm^(-2)and 3.58×10^(9) cm^(-2),respectively.However,the further increment of miscut angles toθ=7°shrink the terrace width less than nucleation distance,and the step-bunching growth mode is dominant.In this circumstance,the misfit strain is released in the initial growth stage,resulting in surface morphology degradation and increased dislocation densities.

Study of the morphology evolution of AlN grown on nanopatterned sapphire substrate

This study focused on the evolution of growth front about AlN growth on nano-patterned sapphire substrate by metal-organic chemical vapor deposition.The substrate with concave cones was fabricated by nano-imprint lithography and wet etching.Two samples with different epitaxy procedures were fabricated,manifesting as two-dimensional growth mode and three-dimensional growth mode,respectively.The results showed that growth temperature deeply influenced the growth modes and thus played a critical role in the coalescence of AlN.At a relatively high temperature,the AlN epilayer was progressively coalescence and the growth mode was two-dimensional.In this case,we found that the inclined semi-polar facets arising in the process of coalescence were{112^-1}type.But when decreasing the temperature,the{112^-2}semi-polar facets arose,leading to inverse pyramid morphology and obtaining the three-dimensional growth mode.The 3 D inverse pyramid AlN structure could be used for realizing 3 D semi-polar UV-LED or facet-controlled epitaxial lateral overgrowth of AlN.

Linear Analysis of Longshore Currents Instability over Mild Slopes

Longshore current instability is important to nearshore hydrodynamic and sediment transport. This paper investigates the longshore current instability growth model based experimental data with different velocity profiles of slopes1:100 and 1:40 by adopting a linear shear instability model with the bottom friction effects. The results show that:(1)Only backshear mode exists in the instability of longshore current for slope 1:40 and frontshear and backshear modes may exist slope 1:100.(2) The peaks of linear instability growth mode for slope 1:100 correspond to three cases: the dominant peak is formed by the joint action of both frontshear and backshear, or by backshear alone without the existence of the smaller peak or formed by either the frontshear or backshear.(3) Bottom friction can decrease the corresponding unstable growth rate but it cannot change the unstable fluctuation period. The results of fluctuation period, wavelength and spatial variation obtained by the analysis of linear shear instability are in good agreement with experimental results.

Kinetic Monte Carlo Simulation of Deposition of Co Thin Film on Cu(001)

A kinetic Monte Carlo （kMC） simulation is conducted to study the growth of ultrathin film of Co on Cu（001） surface. The many-body, tight-binding potential model is used in the simulation to represent the interatomic potential. The film morphology of heteroepitaxial Co film on a Cu（001） substrate at the transient and final state conditions with various incident energies is simulated. The Co covered area and the thickness of the film growth of the first two layers are investigated. The simulation results show that the incident energy influences the film growth and structure. There exists a transition energy where the interracial roughness is minimum. There are some void regions in the film in the final state, because of the influence of the island growth in the first few layers. In addition, there are deviations from ideal layer-by-layer growth at a coverage from 0 - 2 monolayers （ML）.

A Convection-Allowing Ensemble Forecast Based on the Breeding Growth Mode and Associated Optimization of Precipitation Forecast

A convection-allowing ensemble forecast experiment on a squall line was conducted based on the breeding growth mode （BGM）. Meanwhile, the probability matched mean （PMM） and neighborhood ensemble probability （NEP） methods were used to optimize the associated precipitation forecast. The ensemble forecast predicted the precipita- tion tendency accurately, which was closer to the observation than in the control forecast. For heavy rainfall, the pre- cipitation center produced by the ensemble forecast was also better. The Fractions Skill Score （FSS） results indicated that the ensemble mean was skillful in light rainfall, while the PMM produced better probability distribution of pre- cipitation for heavy rainfall. Preliminary results demonstrated that convection-allowing ensemble forecast could im- prove precipitation forecast skill through providing valuable probability forecasts. It is necessary to employ new methods, such as the PMM and NEP, to generate precipitation probability forecasts. Nonetheless, the lack of spread and the overprediction of precipitation by the ensemble members are still problems that need to be solved.

Controlled 2D growth of organic semiconductor crystals by suppressing “coffee-ring” effect

Owing to enhanced charge transport efficiency arising from the ultrathin nature,two-dimensional(2D)organic semiconductor single crystals(OSSCs)are emerging as a fascinating platform for high-performance organic field-effect transistors(OFETs).However,ucoffee-ring"effect induced by an evaporation-induced convective flow near the contact line hinders the large-area growth of 2D OSSCs through a solution process.Here,we develop a new strategy of suppressing the"coffee-ring"effect by using an organic semiconductor:polymer blend solution.With the high-viscosity polymer in the organic solution,the evaporation-induced flow is remarkably weakened,ensuring the uniform molecule spreading for the 2D growth of the OSSCs.As an example,wafer-scale growth of crystalline film consisting of few-layered 2,7-didecylbenzothienobenzothiophene(C10-BTBT)crystals was successfully accomplished via blade coating.OFETs based on the crystalline film exhibited a maximum hole mobility up to 12.6 cm^2·V^-1·s^-1,along with an average hole mobility as high as 8.2 cm^2·V^-1·s^-1.Our work provides a promising strategy for the large-area growth of 2D OSSCs toward high-performance organic electronics.

The importance of H_(2) in the controlled growth of semiconducting single-wall carbon nanotubes

H_(2) is considered an indispensable component of the atmosphere for the growth of high-quality singlewall carbon nanotubes(SWCNTs)by chemical vapor deposition.However,details of the roles H_(2) playing are still unclear due to the complex conditions of SWCNT growth.In this study,we elucidate the functions of H_(2) in the selective growth of semiconducting SWCNTs(s-SWCNTs)by using monodispersed uniform Fe nanoparticles as a catalyst.High-quality s-SWCNTs were synthesized by finely tuning the concentration of H_(2) and the other growth parameters.Experimental data combined with atomistic simulations indicate that H_(2) not only adjusts the concentration of the carbon source,but also serves as a mild etchant that selectively removes small carbon caps grown by a perpendicular mode from the Fe nanoparticles.These results provide useful hints for the controlled growth of SWCNTs with a semiconducting or metallic conductivity,and even a specific chirality.

Manganese carbonate stromatolites of the Ediacaran Doushantuo Formation in Chengkou,northern Yangtze Craton,China

The origin process of manganese ores remains unsolved worldwide.Exploring the origins of stromatolites that contain manganese may be a key to deciphering the sedimentary environments and metallogenic processes of these deposits.However,only a few manganese stromatolites have been discovered and described until now.Microbialites are well developed in the manganese deposits,located near the top of the Ediacaran Doushantuo Formation in Chengkou area of Chongqing,northern Yangtze Craton,but has not been explicitly studied;and whether they are true stromatolites or Epiphyton microbialites remains controversial.Based on field and core observations and thin section microscopy,the characteristics of five types of manganese stromatolites and their growth modes are described in detail in this study.The results show that these stromatolites grew in a biostrome in shoal and lagoon environments and were syngenetic with oncolites and oolites on a carbonate ramp behind the shoal.Manganese stromatolites can be categorized into three forms:(1)stratiform;(2)columnar,which includes branched and columnar types;and(3)stratiform-columnar,which is a transitional type.Based on a criterion that the diameter is less than or greater than 1 mm,columnar stromatolites are further divided into micro-columnar(<1 mm)and columnar(>1 mm)columns,which display synchronous growth and are similar to Pseudogymnosolenaceae.Their shapes are mainly controlled by water depths and hydrodynamic strengths.The greater the water depth,the more columnar the columns tend to be.Excessively strong hydrodynamic conditions decrease the growth rate of stromatolites,and they even stopped growth due to wave damage.Furthermore,pillared laminar textures(not Epiphyton),which consist of dendritic,micro-branched and microcolumnar stromatolites,are a common feature of the larger stratiform,stratiform-columnar and columnar stromatolites.The alternations of laminae with different internal textures record subtle fluctuations in water depths and hydrodynamic strengths,which indicate that stromatolite growth is controlled by tidal cycles at the lamina level.Therefore,it is possible that the vertical evolution of the stromatolites could reveal the changing characteristics of both local and regional sedimentary environments,i.e.,stromatolite shape changes from columnar to stratiform can represent the onset of shallower environments with weak hydrodynamic conditions.In addition,as important reef builders in shallow carbonate ramps,microstromatolites accelerate the development from ramp to platform.Indicators of microbial control on stromatolite shapes and manganese sedimentation processes include the fabric of stromatolite laminae,organic rhodochrosite with a micritic texture that is usually clotted,spherical,tubular,fibrous or dendritic,which suggests that the laminae resulted from microbially induced in situ precipitation.

Impact of surface phase coexistence on the development of step-free areas on Si（111）

The step-flow growth condition of Si on Si（111） near the （7×7）-＂1×1＂ surface phase transition temperature Tc are analyzed within the framework of Burton- Cabrera-Frank theory. In particular, coexistence of both surface phases well below Tc and their specific influence on the step-flow growth behavior are considered. We presume that under dynamical condition of growth, the surface initially covered by only the （7×7） phase separates into domains surrounded by ＂1×1＂ areas. On such a surface, the overall supersaturation should be reduced drastically compared to a surface with only （7×7）, resulting in much larger critical terrace width for nucleation.