Key Techniques and Applications of Adaptive Growth Method for Stiffener Layout Design of Plates and Shells

The application of the adaptive growth method is limited because several key techniques during the design process need manual intervention of designers. Key techniques of the method including the ground structure construction and seed selection are studied, so as to make it possible to improve the effectiveness and applicability of the adaptive growth method in stiffener layout design optimization of plates and shells. Three schemes of ground structures, which are comprised by different shell elements and beam elements, are proposed. It is found that the main stiffener layouts resulted from different ground structures are almost the same, but the ground structure comprised by 8-nodes shell elements and both 3-nodes and 2-nodes beam elements can result in clearest stiffener layout, and has good adaptability and low computational cost. An automatic seed selection approach is proposed, which is based on such selection rules that the seeds should be positioned on where the structural strain energy is great for the minimum compliance problem, and satisfy the dispersancy requirement. The adaptive growth method with the suggested key techniques is integrated into an ANSYS-based program, which provides a design tool for the stiffener layout design optimization of plates and shells. Typical design examples, including plate and shell structures to achieve minimum compliance and maximum bulking stability are illustrated. In addition, as a practical mechanical structural design example, the stiffener layout of an inlet structure for a large-scale electrostatic precipitator is also demonstrated. The design results show that the adaptive growth method integrated with the suggested key techniques can effectively and flexibly deal with stiffener layout design problem for plates and shells with complex geometrical shape and loading conditions to achieve various design objectives, thus it provides a new solution method for engineering structural topology design optimization.

Preparation of Bone-Like Apatite Coating on Surface of Ti-25Nb-2Zr Alloy by Biomimetic Growth Method

A bone-like apatite layer consisting of nano-crystals of apatite phase was prepared on the surface of Ti-25Nb-2Zr alloy by chemical biomimetic growth method. TiNbZr alloy specimens were first oxidized at 500 ℃ for 2 h in the air. Then, they were immersed in 40 ℃ saturated Na2HPO4 solution for 15 h and 25 ℃ saturated Ca(OH)2 solution for 8 h in turn for pre-calcification. The pre-calcified specimens were immersed in modified simulated body fluid up to 15 d for biomimetic growth. After common oxidization, amorphous titania and anatase were detected on the specimen surface. Except for the substantial amount of calcium and phosphorus, no new phase appeared on the pre-calcified specimens. After the coating process, it was found that the (002) orientation was the preferred orientation during the growing period of hydroxyapatite. The inorganic composition and structure of the coating are very similar to those of human thigh bone, which will be advantageous for its application as biomedical material.

Optical and scintillation properties of Ce:Y_(3)Al_(5)O_(12) single crystal fibers grown by laser heated pedestal growth method

The single crystal scintillating optical fibers acting as the scintillators and light conductors show potential application in scintillating fiber array detectors with high spatial resolution.In this paper we report the growth of 0.2 at%Ce:Y_(3)Al_(5)O_(12) single crystal fiber.The crystalline phase,surface morphology of the axialsection and cro ss-section,optical and scintillation properties of the as-grown fiber were investigated.The Ce:Y_(3)Al_(5)O_(12) single crystal fiber has a pure YAG phase,a uniform distribution of cerium in the axialsection and cross-section surface.Emission spectrum is composed of broad bands ranging from 440 to700 nm.In addition,the single crystal fiber has a high light yield of 26115±2000 photons/MeV,low energy resolution of 9.44%@662 keV and decay time of a fast component of 78 ns and a slow component of 301 ns.The intensity ratio of fast to slow components is roughly 8:1.

An in situ growth method for property control of LPCVD polysilicon film

Polysilicon films deposited by low-pressure chemical vapor deposition (LPCVD) exhibit large residual stress and stress gradient, depending on the deposition condition. An in situ growth method based on multilayer concept is presented to control the property for as-deposited polysilicon. A 3-μm thick polysilicon film with nine layers structure is demonstrated under the detailed analysis of multi-layer theory and material characteristic of polysilicon. The results show that a 3-μm-thick polysilicon film with 8-MPa overall residual tensile stress and 2.125-MPa/μm stress gradient through the film thickness is fabricated successfully.

Seed-mediated growth method for high-quality noble metal nanocrystals

This review highlights work from the authors' laboratory on the recent development of seed-mediated growth method for noble metal nanocrystals. The seed-mediated growth method has become one of the most efficient and versatile methods for synthe-sizing high-quality noble metal nanocrystals. The seed-mediated growth method can separate the nucleation and growth stages of metal nanocrystals, and thus provide better control over the size, size distribution, and crystallographic evolution of metal nanocrystals. Because of its high controllability, the seed-mediated growth method is especially promising in providing mechanistic insights into the growth mechanisms of noble metal nanocrystals. In this review, the thermodynamic and kinetic parameters for the nucleation and growth of noble metal nanocrystals are systematically summarized. Mechanistic understanding of these parameters is provided. These studies provide useful guidelines for the rational design and synthesis of novel noble metal nanocrystals with high quality.

Recent progresses in the suppression method based on the growth mechanism of lithium dendrite

Lithium secondary batteries（LSBs） with high energy densities need to be further developed for future applications in portable electronic devices, electric vehicles, hybrid electric vehicles and smart grids. Lithium metal is the most promising electrode for next-generation rechargeable batteries. However, the formation of lithium dendrite on the anode surface leads to serious safety concerns and low coulombic efficiency.Recently, researchers have made great efforts and significant progresses to solve these problems. Here we review the growth mechanism and suppression method of lithium dendrite for LSBs’ anode protection. We also establish the relationship between the growth mechanism and suppression method. The research direction for building better LSBs is given by comparing the advantages and disadvantages of these methods based on the growth mechanism.

Effect of culture methods on individual variation in the growth of sea cucumber Apostichopus japonicus within a cohort and family

There is substantial individual variation in the growth rates of sea cucumber Apostichopus japonicus individuals. This necessitates additional work to grade the seed stock and lengthens the production period. We evaluated the infl uence of three culture methods(free-mixed, isolated-mixed, isolated-alone) on individual variation in growth and assessed the relationship between feeding, energy conversion efficiency, and individual growth variation in individually cultured sea cucumbers. Of the different culture methods, animals grew best when reared in the isolated-mixed treatment(i.e., size classes were held separately), though there was no difference in individual variation in growth between rearing treatment groups. The individual variation in growth was primarily attributed to genetic factors. The difference in food conversion efficiency caused by genetic differences among individuals was thought to be the origin of the variance. The level of individual growth variation may be altered by interactions among individuals and environmental heterogeneity. Our results suggest that, in addition to traditional seed grading, design of a new kind of substrate that changes the spatial distribution of sea cucumbers would effectively enhance growth and reduce individual variation in growth of sea cucumbers in culture.

Analysis on high-temperature oxidation and growth stress of iron-based alloy using phase field method

High-temperature oxidation is an important property to evaluate thermal protection materials. However, since oxidation is a complex process involving microstructure evolution, its quantitative analysis has always been a challenge. In this work, a phase field method （PFM） based on the thermodynamics theory is developed to simulate the oxidation behavior and oxidation induced growth stress. It involves microstructure evolution and solves the problem of quantitatively computational analysis for the oxidation behavior and growth stress. Employing this method, the diffusion process, oxidation performance, and stress evolution axe predicted for Fe-Cr-A1-Y alloys. The numerical results agree well with the experimental data. The linear relationship between the maximum growth stress and the environment oxygen concentration is found. PFM provides a powerful tool to investigate high-temperature oxidation in complex environments.

3D anisotropy simulation of dendrites growth with phase field method

The anisotropy problem of 3D phase-field model was studied,and various degrees of anisotropy were simulated by numerical calculation method.The results show that with the change of interface anisotropy coefficients,from smooth transition to the appearance of angle,equilibrium crystals shape morphology has a critical value,and 3D critical value is 0.3.The growth of dendrites is stable and the interface is smooth when it is less than critical value;the interface is unstable,rolling edge appears and the growth is discontinuous when it is more than critical value.With the increase of anisotropy coefficients,the dendrites grow faster under the same condition.

A Novel Deflection Method for Measuring the Growth Stress of Thermally Growing Oxide Scales

A kind of new deflection technique has been developed for measuring the growth stress of thermally growing oxide scales during high temperature oxidation of alloys. The average growth stresses in oxide scales such as Al2O3, NiO and Cr2O3 formed on the surface of the superalloys can be investigated by this technique. Unlike the comventional deflection method, the novel method does not need to apply a coating for preventing one main face of thin strip specimen from oxidizing and can be used under the condition of longer time and higher temperature.

Preparation,Growth Mechanisms and Characterizations of ZnSe Films via the Solvothermal Method

With diethylamine as a solvent, ZnSe films were formed on the Si substrate directly from zinc and selenium through the modified solvothermal method. The effects of holding temperature, deposition time and substrate surface treatment on the quality and morphologies of the ZnSe films were investigated. The growth mechanism of ZnSe films was proved to be a layer-nucleation growth process, which was tied in with the Stranski-Krastanov （SK） model. ZnSe films were identified by the X-ray diffraction pattern （XRD）, the scanning electron microscope （SEM）, the X-ray photoelectron spectroscope （XPS） and the photoluminescence （PL） techniques. The results indicate that the modified solvothermal method with diethylamine as a solvent is suitable to prepare high quality ZnSe films.

Discrepancies in Growth Measurement Methods of Mosses: An Example from Two Keystone Species Grown under Increased CO₂and N Supply in a Restored Peatland

Bryophytes dominate northern peatlands. Obtaining reliable measurements of moss-growth and how it may be affected by global changes are therefore important. Several methods have been used to measure moss-growth but it is unclear how comparable they are in different conditions and this uncertainty undermines comparisons among studies. In a field experiment we measured the growth and production of Sphagnum fallax (Sphagnum) and Polytrichum strictum (Polytrichum) using two handling methods, using cut and uncut plants, and three growth-variables, height-growth, length-growth, and mass-growth. We aimed “benchmarking” a combination of six methodological options against exactly the same set of factorial experiments: atmospheric CO2 enrichment and N addition. The two handling methods produced partly different results: in half of the cases, one method revealed a significant treatment effect but the other one did not: significant negative effects on growth were only observed on uncut plants for elevated CO2 and on cut plants for N addition. Furthermore, the correspondence between measurements made with various growth-variables depended on the species and, to a lesser extent, treatments. Sphagnum and Polytrichum growth was inhibited under elevated CO2, and correlated to higher ammonium values. Sphagnum was however less affected than Polytrichum and the height difference between the two species decreased. N addition reduced the P/N ratio and probably induced P-limiting conditions. Sphagnum growth was more inhibited than Polytrichum and the height difference between the two species increased. Our data show that such a problem indeed exists between the cut and uncut handling methods. Not only do the results differ in absolute terms by as much as 82% but also do their comparisons and interpretations depend on the handling method—and thus the interpretation would be biased—in half of the cases. These results call for caution when comparing factorial studies based on different handling methods.

Effects of Different Irrigation Methods on Growth,Fruit Quality and Yield of Apple Trees

Water-saving irrigation is an important way to realize the sustainable development of the apple industry.In order to screen the best irrigation pattern for apple,taking 9-year-old‘Yanfu 10'Fuji/Malus robusta apple as the material,the effects of different irrigation methods(drip irrigation,sprinkling irrigation,and flood irrigation) on the growth,fruit quality,and yield of apple trees were studied.The results showed that compared with the flood irrigation,drip irrigation and sprinkling irrigation significantly increased the spring shoot length by 14.8%and 9.1%,respectively,and decreased the autumn shoot length by 11.7% and 8.8%,respectively.Drip irrigation and sprinkling irrigation significantly increased the leaf area,chlorophyll content,and leaf weight,the leaf area increased by 3.0% and 1.9%,respectively,the chlorophyll content increased by 13.9% and 11.5%,respectively,and the leaf weight increased by 5.8% and 5.1%,respectively.Drip irrigation and sprinkling irrigation could slightly increase the single fruit weight and fruit shape index,significantly increase the coloring index and smoothness index.The single fruit weight increased by 3.2% and 1.9%,the coloring index increased by 6.1% and 4.1%,the smoothness index increased by 4.7% and 2.8%,and the proportion of red fruit increased by 4.2% and 2.2%,respectively.The content of soluble solids in drip irrigation and sprinkling irrigation was significantly higher than that in flood irrigation,which was 13.0% and 2.6% higher than CK,respectively.The fruit hardness in drip irrigation and sprinkling irrigation was 7.9% and 2.2% higher than CK,respectively,and that in drip irrigation increased significantly.The yield in drip irrigation and sprinkling irrigation was 12.1% and 8.2% higher than CK,respectively.In conclusion,drip irrigation and sprinkling irrigation could promote the growth of apple trees,improve the fruit quality,and increase the yield of apple trees,and the effect of drip irrigation is better than sprinkling irrigation.

Fatigue crack growth rate test using a frequency sweep method

Fatigue crack propagation characteristics of a diesel engine crankshaft are studied by measuring the fatigue crack growth rate using a frequency sweep method on a resonant fatigue test rig. Based on the phenomenon that the system frequency will change when the crack becomes large, this method can be directly applied to a complex component or structure. Finite element analyses (FEAs) are performed to calibrate the relation between the frequency change and the crack size, and to obtain the natural frequency of the test rig and the stress intensity factor (SIF) of growing cracks. The crack growth rate i.e. da/dN-ΔK of each crack size is obtained by combining the testing-time monitored data and FEA results. The results show that the crack growth rate of engine crankshaft, which is a component with complex geometry and special surface treatment, is quite different from that of a pure material. There is an apparent turning point in the Paris's crack partition. The cause of the fatigue crack growth is also dis-cussed.

Studies on the Synthesis, Growth and Characterization of ([Paranitrophenyl]Imino)Benzene NLO Crystal by Sankaranarayanan-Ramasamy Method

The study of imine-bridged organics has been the hot spot synthesis of second order nonlinear optical (SONLO) and photo-responsive materials in recent years. Herein we present a study of synthesis, growth, and characterization of ([paranitrophenyl]imino)benzene (PNPIB) NLO single crystal. The title compound was synthesized in one step by Schiff base formation. PNPIB single crystal of diameter of 40 mmand length 50 mmwas successfully grown by SR method using a seed as the nucleus. The growth rate formula is derived for the SR method. PNPIB single crystals of 10 mmdiameter and 60 mmheight have been grown at an average growth rate of 3 mmper day from the point seed in a glass crystallizer. Almost 100% stable crystal conversion efficiency was achieved. The as grown PNPIB crystals were characterized using single crystal X-ray diffraction (XRD), X-ray powder diffraction (XRPD), Fourier Transform Infrared (FTIR), Ultraviolet-Visible-Near Infrared (UV-Vis-NIR), 1H & 13C NMR spectral studies, dielectric measurement and NLO studies. Single crystal XRD analysis confirms that the grown ingot belongs to the space group of P2 of monoclinic system thus exhibiting noncentrosymmetric structure. The crystalline perfection was assessed by XRPD. The powder diffraction pattern of the grown crystal has been indexed. The presence of C=N bond with intramolecular hydrogen bonding and the protonation of ions were confirmed by FTIR analysis. The UV-Vis-NIR spectrum of the crystal shows that the crystal has a cut-off at 298 nm. The 1H & 13C NMR spectra confirm the molecular structure. The dielectric behaviour was measured in the frequency range 1 KHz - 10 KHz for the temperature range from 30℃ to 170℃. The slight decrease in dielectric constant has been observed as the frequency is increased and the dielectric loss is very low for the entire frequency range. The second harmonic generation (SHG) in the crystal was observed by Kurtz powder technique.

Application of the Method of Characteristics to Population Balance Models Considering Growth and Nucleation Phenomena

The population balance modeling is regarded as a universally accepted mathematical framework for dynamic simulation of various particulate processes, such as crystallization, granulation and polymerization. This article is concerned with the application of the method of characteristics (MOC) for solving population balance models describing batch crystallization process. The growth and nucleation are considered as dominant phenomena, while the breakage and aggregation are neglected. The numerical solutions of such PBEs require high order accuracy due to the occurrence of steep moving fronts and narrow peaks in the solutions. The MOC has been found to be a very effective technique for resolving sharp discontinuities. Different case studies are carried out to analyze the accuracy of proposed algorithm. For validation, the results of MOC are compared with the available analytical solutions and the results of finite volume schemes. The results of MOC were found to be in good agreement with analytical solutions and superior than those obtained by finite volume schemes.

Grain Growth Kinetics of SnO_2 Nanocrystals Synthesized by Precipitation Method

Monodispersed spheroidal SnO2 nanocrystals with the grain size of 8-30 nm were synthesized by the precipitation method using SnCl4·5H2O （stannic chloride hydrate） as raw materials.Differential scanning calorimetry/thermogravimetry （DSC/TG）,X-ray diffraction （XRD） and transmission electron microscope （TEM） were used to characterize the structure of SnO2 nanocrystals.The influences of the calcination temperature and time on the lattice constant,the lattice distortion and the grain size of SnO2 nanocrystals were discussed based on the XRD results.The grain growth kinetics of SnO2 nanocrystals during calcination process was simulated with a conventional grain growth model which only took into account of diffusion and with a new isothermal model proposed by our group,which took into account of both diffusion and surface reactions.Using conventional model,the grain growth rate constant of SnO2 crystals is 1.55×104nm5/min with a pre-exponential factor of 5 and an activation energy of 108.62 kJ/mol.Compared with the convention model,the new isothermal model is more realistic in reflecting the grain growth behavior of SnO2 nanocrystals during the calcination process.This indicates that the grain growth of SnO2 nanocrystals is controlled by both diffusion and reaction factors,and the effect of surface reactivity on the grain growth of SnO2 nanocrystals could not be ignored.A combined activation energy estimated with the new isothermal model is 53.46 kJ/mol.

Quantifying growth and breakage of agglomerates in fluid-particle flow using discrete particle method

The cohesive solids in liquid flows are featured by the dynamic growth and breakage of agglomerates, and the difficulties in the development, design and optimization of these systems are related to this significant feature.In this paper, discrete particle method is used to simulate a solid–liquid flow system including millions of cohesive particles, the growth rate and breakage rate of agglomerates are then systematically investigated. It was found that the most probable size of the agglomerates is determined by the balance of growth and breakage of the agglomerates the cross point of the lines of growth rate and breakage rate as a function of the particle numbers in an agglomerate, marks the most stable agglomerate size. The finding here provides a feasible way to quantify the dynamic behaviors of growth and breakage of agglomerates, and therefore offers the possibility of quantifying the effects of agglomerates on the hydrodynamics of fluid flows with cohesive particles.

Study on the Bubble Growth and Departure with A Lattice Boltzmann Method

For the growth and departure of bubbles from an orifice, a free energy lattice Boltzmann model is adopted to deal with this complex multiphase flow phenomenon. A virtual layer is set at the boundary of the flow domain to deal with the no-slip boundary condition. Effects of the viscosity, surface tension, gas inertial force and buoyancy on the characteristics of bubbles when they grow and departure from an orifice in quiescent liquid are studied. The releasing period and departure diameter of the bubble are influenced by the residual gas at the orifice, and the interaction between bubbles is taken into consideration. The relations between the releasing period or departure diameter and the gravity acceleration show fair agreements with previous numerical and theoretical results. And the influence of the gas outflow velocity on bubble formation is discussed as well. For the bubbles growing in cross-flow field, effects of the cross-flow speed and the gas outflow velocity on the bubble formation are discussed, which is related to the application in ship resistance reduction. And optimal choice of the ship speed and gas outflow velocity is studied. Cases in this paper also prove that this high density ratio LBM model has its flexibility and effectiveness on multiphase flow simulations.