基于生长机的芦苇形态模型可视化研究

兼顾植物生理功能的形态发生模型,是在计算机上实现模拟植物生长发育的理论依据。通过观察芦苇生长过程中发生的形态及生理变化,分析了形态结构与生理因子之间的内在关系,并提出一种基于生长机的芦苇形态建模方法。根据生成的形态模型有效组织芦苇生长时产生的大量数据,并建立其可视化流程。通过模拟实验,结果表明该模型能有效地模拟芦苇的生长发育过程。

基于生长机的虚拟植物可视化技术研究

虚拟植物在真实再现植物生长过程及在精确农业、遥感监测等领域都有非常广阔的应用前景。本文从植物生长建模的角度出发,着重阐述了基于生长机的虚拟植物生长可视化方面采用的一些方法及关键技术,并在此基础上提出了有待进一步解决的主要问题。对虚拟植物生长的可视化技术在虚拟试验、农田管理、教学等方面的应用进行了展望。

虚拟植物生长机模型构建技术研究

针对虚拟植物在农林业中的应用,提出了基于双尺度自动机的"生长机"模型构建技术,对生理生态模型和形态发生模型的接口进行了定义,并兼顾生长机模型构建的普适性,采用模块化设计,减少了由于专用模型修改带来的大量代码改动,该技术经过验证取得了预期效果。

百合鳞茎的生长建模与可视化模拟

构造了百合鳞片的生长机与可视化模型,并根据鳞片轮生抱合形成鳞茎的生长机理,构建鳞茎生长的可视化模拟系统。鳞片视为向线生长的生长趋势,每生长一小段就向中心茎秆偏转一定角度;鳞片采用四边形图元绘制的双半椭圆台进行可视化建模,其中截面是月牙形,由两个长半轴相等短半轴不相等的半椭圆围合而成。结果表明该系统能形象地模拟百合鳞茎的生长与抱合过程。

生态力与山城生长

通过山城形成（生）与发展（长）的直接机因和间接机因分析指出，生态要素的作用力──生态力是制约和促进山城生长的重要机因．

陆稻苗期生长建模及仿真

设计陆稻种植试验获取陆稻苗期植株的几何构型参数和生长参数,构造出陆稻地上部分及与地下部分的生长机与可视化模型。基于模型,在Linux操作系统下,利用C++以及Mesa图形库开发出陆稻苗期三维可视化动态模拟仿真系统,并对可视化系统进行精度评估。结果表明,仿真三维实体模型在形态特征上与实际陆稻植株相似,仿真数据与实测数据相对误差较小,均在10%以内。

Hydrothermal synthesis, characterization and optical properties of La_2Sn_2O_7:Eu^(3+) micro-octahedra

Pyrochlore structure La2Sn2O7：Eu3＋ microcrystals with uniform octahedron shape were successfully synthesized via a hydrothermal route at 180 °C for 36 h. The crystal structure, particle size, morphologies, and optical properties of the as-synthesized products were investigated by XRD, TEM, SEM, EDS, FT-IR, Raman spectroscopy and PL. The effects of pH of precursor solution, precursor concentration, reaction temperature, and time were investigated. The results reveal that pH of the precursor solution not only plays an important role in determining the phase of the as-synthesized products, but also has a significant influence on the morphologies of the samples. High-quality and uniform octahedrons with an average size of about 700 nm could be easily obtained at the pH value of 12. The possible formation mechanism of octahedral-like La2Sn2O7：Eu3＋ microcrystals was briefly proposed. The photoluminescence spectra show that La2Sn2O7：Eu3＋ micro-octahedra display stronger emission in the range of 582-592 nm compared with the samples with other shapes.

Characterization of SiC nanowires prepared on C/C composite without catalyst by CVD

SiC nanowires were prepared on C/C composite surface without catalyst by chemical vapor deposition（CVD） using CH3 SiCl3 as precursor.SEM images of the CVD-product reveal that some long nanowires have grown to tens of micrometers with some gathered as a ball.Some short nanowires agglomerate like chestnut shell with many thorns accompanied by some deposited nano-particles.XRD,Raman-spectrum and FTIR patterns indicate that the product is a typical β-SiC.TEM images show that the nanowires have a wide diameter range from 10 to 100 nm,and some thin nanowires are bonded to the thick one by amorphous CVD-SiC.A SiC branch generates from an amorphous section of a thick one with an angle of 70° between them,which is consistent with the [111] axis stacking angle of the crystal.SAED and fast Fourier transform（FFT） patterns reveal that the nanowires can grow along with different axes,and the bamboo-nodes section is full of stacking faults and twin crystal.The twisted SiC lattice planes reveal that the screw dislocation growth is the main mechanism for the CVD-SiC nanowires.

Microstructure evolution of Al-Ti liquid-solid interface

Al-Ti diffusion couples were made by embedded technology and treated at the temperature between the melting points of Al and Ti. The microstructure evolution and growth mechanism of the Al-Ti DRZ were investigated. The result shows that the DRZ, the mixture of TiAl3 and Al, grows layer by layer along their chemical equilibrium zone. In the course, the growth interface moves toward the aluminum side. TiAl3 is the only new phase which forms earliest in the course of heat-treatment. The growth mechanism of the DRZ changes after the phase transition of titanium. Before the phase transition of titanium, the growth of the DRZ is controlled by the dissolution speed of the titanium to the molten aluminum, while after the phase transition of titanium, the growth is controlled by the chemical reaction speed of Al and Ti atoms, and consequently, its growth rate is greatly increased.

Shape-controlled synthesis of novel precursor for fibrous Ni-Co alloy powders

A novel precursor of nickel-cobalt alloy powders with an appropriate Ni to Co molar ratio was prepared under selectively synthetic conditions. The composition and morphology of the precursor were characterized by X-ray diffractometry （XRD）, scanning electron microscopy （SEM）, Fourier transform infrared spectrometry （FT-IR） and energy dispersive spectrometry （EDS）. The effects of pH value, reaction temperature, metal ion concentrations and surfactant on the morphology and the dispersion of precursor were investigated. The results show that the morphology of precursor depends on ammonia content in the precursor. A fibriform precursor is a complicated ammonia-containing nickel-cobalt oxalate. The uniform shape-controlled fibrous precursor is obtained under the following optimum conditions： ammonia as complex agent as well as pH adjustor, oxalate as coprecipitator, 50-65 °C of reaction temperature, 0.5-0.8 mol/L of total concentration of Ni2＋ and Co2＋, PVP as dispersant, and pH 8.0-8.4.

Phase-field simulations of forced flow effect on dendritic growth perpendicular to flow

The effect of supercooled melt forced laminar flow at low Reynolds Number on dendritic growth perpendicular to melt flow direction was investigated with the phase-field method by incorporating melt convection and thermal noise under non-isothermal condition. By taking the dendritic growth of high pure succinonitrile （SCN） supercooled melt as an example, side-branching shape difference of melts with flow and without flow was analyzed. Relationships among supercooled melt inflow velocity, deflexion angle of dendritic arm and dendritic tip growth velocity were studied. Results show that the melt inflow velocity has few effects on the dendritic tip growth velocity. A formula of relationship between the velocity of the melt in front of primary dendritic tip and the dendritic growth time was deduced, and the calculated result was in quantitative agreement with the simulation result.

Mechanism of Nutrient Silicon and Water Temperature Influences on Phytoplankton Growth

This paper analyzed how nutrient silicon and water temperature influenced the variation of phytoplankton growth and the change of its assemblage structure, and probed the different characteristics of the variation of phytoplankton growth and the different profiles of the change of its assemblage structure influenced by nutrient silicon and water temperature. Taking Jiaozhou Bay for example, this paper showed the process of both the variation of phytoplankton growth and the change of its assemblage structure, unveiled the mechanism of nutrient silicon and water temperature influencing the variation of phytoplankton growth and the change of its assemblage structure, and determined that nutrient silicon and water temperature were the motive power for the healthy running of the marine ecosystem.

Phase-field simulation of forced flow effect on random preferred growth direction of multiple grains

The random distribution problem of dendrite preferred growth direction was settled by random grid method.This method was used to study the influence of forced laminar flow effect on multiple grains during solidification.Taking high pure succinonitrile （SCN） undercooled melt as an example,the forced laminar flow effect on multiple grains was studied by phase-field model of single grain which coupled with flow equations at non-isothermal condition.The simulation results show that the random grid method can reasonably settle the problem of random distribution and is more effective.When the solid fraction is relatively low,melt particles flow around the downstream side of dendrite,and the flow velocity between two dendrite arms becomes high.At the stage of solidification time less than 1800Δt,every dendrite grows freely;the upstream dendrites are stronger than the downstream ones.The higher the melt flow rate,the higher the solid fraction.However,when the solid fraction is relatively high,the dendrite arm intertwins and only a little residual melt which is not encapsulated can flow;the solid fraction will gradually tend to equal to solid fraction of melt without flow.

ZnO Nanobelts and Hollow Microspheres Grown on Cu Foil

ZnO nanobelts, hollow microspheres, and urchins have been prepared on copper foil via a simply low temperature evaporation route. The microstructure, morphologies, and photolu-minescence of the ZnO nanostructures were studied with X-ray diffraction, Raman spectra, scanning electron microscopy and photoluminescence spectra. The width of the nanobelts was about 500 nm and the length was longer than 10μm. The diameter of the hollow microspheres was between 5 and 10μm. A possible growth mechanism of the nanobelts, microspheres and urchins was proposed. The photoluminescence spectrum exhibited strong deep level energy emissions and a weak near band edge emission. These ZnO nanostructures on a copper substrate have the advantages of naturally good adhesion and electrical connection between the ZnO nanostructures and the conductive substrate.

Growth Mechanism of Microcrystalline Silicon Films by Scaling Theory and Monte Carlo Simulation

Hydrogenated microcrystalline silicon （~c-Si：H） films with a high deposition rate of 1.2nm/s were prepared by hot-wire chemical vapor deposition （HWCVD）. The growth-front roughening processes of the μc-Si..H films were investi- gated by atomic force microscopy. According to the scaling theory, the growth exponent β≈0.67, the roughness exponent α≈0.80,and the dynamic exponent 1/z = 0.40 are obtained. These scaling exponents cannot be explained well by the known growth models. An attempt at Monte Carlo simulation has been made to describe the growth process of μc-Si： H film using a particle reemission model where the incident flux distribution,the type and concentration of growth radical, and sticking,reemission,shadowing mechanisms all contributed to the growing morphology.

Effect of Different Organic Fertilizers on Chinese Chives(Allium tuberosum) Growth and Yield

[Objeclive] This study was conducted to select suitable organic fertilizer for Chinese chives, so as to improve yield and benefit of Chinese chives. [Method] Pot experiments were carried out to investigate effects of 3 organic fertilizers peanut cake fertilizer, chicken manure and mushroom residue on growth and yield of Chi- nese Chives. [Result] The 3 organic fertilizer treatments had better effects on plant height, stem diameter and leaf width than the CK. Treatment 1 showed the best effect on growth and development of Chinese chives, treatment 2 exhibited the sec- ond best effect, and treatment 3 showed the poorest effect. Treatment 1 showed the highest yield and economic benefit, of 65.514 t/hm^2 and 175.556×10^4 Yuardhm2, respectively, treatment 2 showed the second highest effects, and treatment 3 showed the lowest yield and economic benefit. [Conclusion] Selecting peanut cake fertilizer for production of Chinese chives could significantly improve yield and eco- nomic benefit of Chinese chives.

Measurement of Refractive Indices of (Al_xGa_(1-x))_(0.51)In_(0.49)P Grown by Low Pressure Organometallic Vapor Phase Epitaxy

The refractive indices of disordered (Al xGa 1-x ) 0 51 In 0 49 P,which is grown by low-pressure organometallic vapor phase epitaxy and lattice-matched to GaAs substrate,have been determined by measuring their reflectance spectra when the wavelength ranges between 0 5 to 2 5 micrometer.A single-oscillator dispersion model is used to verify the experiment data and calculate the reflectance spectrum.The refractive indices are used to analyze the waveguide of strain quantum well GaInP/AlGaInP visible laser diode.The simulated far field pattern is consistent with the experimental results very well.

Investigation of GaN Growth Directly on Si (001) by ECR Plasma Enhanced MOCVD

Direct growth of GaN films on Si(001) substrate at low temperatures (620～720℃) by electron cyclotron resonance (ECR) microwave plasma enhanced metalorganic chemical vapor deposition (PEMOCVD).The crystalline phase structures of the films are investigated.The results of high resolution transmission electron microscopy (HRTEM) and X ray diffraction (XRD) indicate that high c axis oriented crystalline wurtzite GaN is grown on Si(001) but there is an amorphous layer formed naturally at GaN/Si interface.Both faces of the amorphous layer are flat and sharp,and the thickness of the layer is 2nm approximately cross the interface.The analysis supports that β GaN phase is not formed owing to the N x Si y amorphous layer induced by the reaction between N and Si during the initial nucleation stage.The results of XRD and atomic force microscopy (AFM) indicate that the conditions of substrate surface cleaned in situ by hydrogen plasma,GaN initial nucleation and subsequent growth are very important for the crystalline quality of GaN films.