-
Research advances in eco-hydrological process and function
Present studies on the coupling relationship and hydrology mechanism between basin ecosystem and hydrological process has become an international research frontier in hydrology. This paper investigates this coupling relationship, and also summarizes research and presents a method of combining isotopic technology with hydro-chemical methods, for the study of eco-hydrological process and function in different landscape zones. We then examine research trends for future direction and development of this field....
2020-11-10 09:33:08浏览：66
查看 -
Synthesis of Yttrium Oxide Nanocrystal via Solvothermal Process
Y2O3 nanomaterials have been widely used in transparent ceramics and luminescent devices. Recently there are many studies focusing on controlling the size and morphology of Y2O3 in order to obtain better materials performance. In present study, yttrium oxyhydroxide precursor was synthesized via a facile solvothermal process through the dissolution-recrystallization mechanism of Y2O3 raw powders in the ethylenediamine solvent, then nanosized yttrium oxide crystal was prepared from the precursor through post heat treatment process. The effects of solvothermal treatment temperature, holding time, solvent kinds and post heat treatment parameters on crystalline structure, grain shape and size of nanocrystal were investigated by XRD, TEM and TGA-DTA measurements. TEM images reveal that the morphology of product after post heat treatment at 460 ℃ for 12 h is rice-like nanocrystal. XRD shows that this product is pure cubic Y2O3 cphase. Present study reveals that high purity Y2O3 with rice-like morphology can be easily prepared with average size around 30 nm under suitable post heat treatment parameters. In addition, the effects of solvents such as water and ethanol etc. on the crystal structure and morphology were also investigated. It is suggested that dissolution-recrystallization process may be the main mechanism for the formation of nano-sized YOOH precursors under solvothermal reaction condition, and the ethylenediamine solvent is likely to play an important role in controlling the transformation process of yttria precursors to theY2O3 nanocrystal....
2020-11-10 09:33:08浏览：57
查看 -
EXPERIMENTS OF INFLUENCE OF DISCHARGE PROCESS ON CHANNEL PATTERN
Based on experimental data and theory, by means of simplified discharge durations in a small flume,the influence of discharge process on channel morphology and channel pattern was analyzed in this paper. It was concluded that on the same original channel, different discharge and channel conditions would end with different river morphology, including thalwegs and radius of bends. Different discharge process resulted in two kinds of change:tiny change in the process of "big-small-big" and distinct change in the process of "small-big-small". Flood discharge duration was verified to be the main cause in the discharge process. Proper discharge process will change the morphologies of river, even can led to channel pattern transformation. The influences based on the relationship between the flow and the channel itself, including slope and riverbed constitution. Although not be a main cause, original channel morphology may influence its final channel pattern. Neglecting the influence of channel itself will hamper the understanding of channel patterns....
2020-11-10 09:33:08浏览：60
查看 -
THE STUDY ON MECHANISM OF BINDER MIGRATION DURING COATING PROCESS
Binder migration during coating process and the mechanism of binder migration were studied in this paper. After the latex was tagged by osmium, the degree of binder migration was measured by energy-dispersive X-ray spectrometer. For the wet sample just after coating application, the real information of binder distribution was kept by quenching the sample in liquid nitrogen followed by freeze-drying. The results showed: under the condition of this research, binder migration occurred both in the process of coating application and drying.But the amount of binder migration occurred during coating application was much little than that occurred during drying. The mechanism of binder migration during the process of coating application was studied by force analyses. And one viewpoint was proposed that was binder migration was caused by Magnus force and Saffman force....
2020-11-10 09:33:08浏览：83
查看 -
Construction Process Control of Large Extra Caissons
The complexity of geotechnical engineering and variability in construction circumstances of large extra caissons make the problem of maintaining appropriate sink attitude quite difficult, especially in keeping sink uniformity and achieving the expected final sink depth. A new construction control method is presented using (H∞) theory, considering uncertainties in the mechanics model and external noise in the construction site parameters. The design method of an (H∞) controller has consequently been obtained for large extra caissons. Control results using only constructor experiences are compared with simulation results using the (H∞) controller for a practical engineering situation, which indicates that the (H∞) controller is successful in maintaining sink uniformity, avoiding sink as well as in achieving the expected final sink depth....
2020-11-10 09:33:08浏览：47
查看 -
Numerical simulation for thermal flow filling process of casting
The solution algorithm (SOLA) method was used to solve the velocity and pressure field of the thermal flow filling process, and the volume of fluid (VOF) method for the free surface problem. Since the "donor-acceptor" rule often results in the free interface vague, the explicit difference method was adopted, and a method describing the free surface state at 0＜F＜1 was proposed to deal with this problem. In order to raise the computation efficiency, such algorithms were investigated and invalidated as: 1) internal and external area separation simplification algorithm; 2) the reducing necessary search area method. With the improved algorithms, the filling processes of the valve cover castings with gravity cast and an up cylinder block casting with low-pressure cast were simulated, the simulation results are believable and the computation efficiency is greatly improved. The SOLA-VOF model and its difference method for thermal fluid flow filling process were introduced....
2020-11-10 09:33:08浏览：63
查看 -
Numerical and experimental analysis of quenching process for cam manufacturing
In order to obtain satisfactory mechanical properties for the cam used in high-power ship diesel engines, a new quenching technology was proposed by designing a two-stage quenching process with an alkaline bath as the quenching medium. To demonstrate the effectiveness of the proposed new quenching technology, both numerical analysis and experimental study were performed. The new quenching technology was analyzed using finite element method. The combined effects of the temperature, stress and microstructure fields were investigated considering nonlinear material properties. Finally, an experimental study was performed to verify the effectiveness of the proposed new quenching technology. The numerical results show that internal stress is affected by both thermal stress and transformation stress. In addition, the direction of the internal stress is changed several times due to thermal interaction and microstructure evolution during the quenching process. The experimental results show that the proposed new quenching technology significantly improves the mechanical properties and microstructures of the cam. The tensile strength, the impact resistance and the hardness value of the cam by the proposed new quenching technology are improved by 4.3%, 8.9% and 3.5% compared with those by the traditional quenching technology. Moreover, the residual stress and cam shape deformation are reduced by 40.0% and 48.9% respectively for the cam manufactured by the new quenching technology....
2020-11-10 09:33:08浏览：59
查看 -
Effect of Drilling Process on Fatigue Life of Open Holes
In this paper,a series of fatigue tests were performed to study the effect of drilling process on fatigue behavior of open holes in dog-bone specimens drilled by the traditional drilling process and advanced Winslow drilling process.The evaluations of initial fatigue qualities of the two types of holes were carried out based on the equivalent initial flaw size method and coincidence criterion.Fatigue fracture surfaces were observed by stereomicroscope.The results show that the location where the fatigue crack initiates is unchanged when these two different drilling processes are used.A longer fatigue life shows a more severe dispersibility.When the Winslow drilling process is adopted,the equivalent initial flaw size is smaller than 0.125 mm.The Winslow drilling process meets the requirement of coincidence criterion....
2020-11-10 09:33:08浏览：67
查看 -
Effect of Drilling Process on Fatigue Life of Open Holes
In this paper,a series of fatigue tests were performed to study the effect of drilling process on fatigue behavior of open holes in dog-bone specimens drilled by the traditional drilling process and advanced Winslow drilling process.The evaluations of initial fatigue qualities of the two types of holes were carried out based on the equivalent initial flaw size method and coincidence criterion.Fatigue fracture surfaces were observed by stereomicroscope.The results show that the location where the fatigue crack initiates is unchanged when these two different drilling processes are used.A longer fatigue life shows a more severe dispersibility.When the Winslow drilling process is adopted,the equivalent initial flaw size is smaller than 0.125 mm.The Winslow drilling process meets the requirement of coincidence criterion....
2020-11-10 09:33:08浏览：81
查看 -
Numerical prediction of the incremental melting and solidification process
A mathematical formulation is applied to represent the phenomena in the incremental melting and solidification process (IMSP), and the temperature and electromagnetic fields and the depth of steel liquid phase are calculated by a finite difference technique using the control volume method. The result shows that the predicted values are in good agreement with the observations. In accordance with the calculated values for different kinds of materials and different size of molds, the technological parameter of the IMS process such as the power supply and the descending speed rate can be determined....
2020-11-10 09:33:08浏览：70
查看 -
An Improved Analytic Hierarchy Process and Application in Grain Production
Value analysis of grain production influencing factors is a complex decision problem. This paper introduced a modified Analytic Hierarchy Process （AHP） accumulation factor, namely Solving Weight by AHP＇s Accumulation Factor Sequence Evaluating Data. We used the arithmetical average to replace the expert marking, so that the possible decision mistakes by the subjective judgments could be avoided. We computed the case with this method, which obtained attribute value of 17 influencing factors of the potential food production in Heilongjiang Province, and the result of which was reasonable...
2020-11-10 09:33:08浏览：64
查看 -
CURING PROCESS OF PHOTOPOLYMER RESIN BOND DIAMOND TOOLS
Analytical simulation and corresponding proof-test are adopted to study the principle of the curing process of photopolymer resin diamond tools. The influence of the diamond as abrasives in photopolymer resin owing to the absorptivity of the diamond for the UV light on the photopolymer resin curing process is discussed. Based on the above, a kind of diamond tool-dicing blade is selected to analyze the curing process of photopolymer bond diamond tools. An analytical model of curing process is developed and a correlation curve between the depth of polymerization of the photopolymer resin diamond tools and the exposure time to represent the curing process of photopolymer bond dicing blade. A test is done to proof-test the validity of the analytical model and the correlation curve. The simulated data fit the experimental results, which demonstrates the analytical models and numerical algorithm are of high reliability. The analytical simulation method could possibly be used to optimize the curing cycle and improve the quality of the photopolymers resin bond diamond tools....
2020-11-10 09:33:08浏览：57
查看 -
Kinetic Behavior of Aggregation-Fragmentation Process with Annihilation
The kinetic behavior of an aggregation-fragmentation-annihilation system with two distinct species is stead-ied. We propose that the aggregation reaction occurs only between two clusters of the same species, and the irreversibleannihilation reaction occurs only between two clusters of different species, meanwhile there exists the fragmentationreaction of a cluster into two smaller clusters for either species. Based on the mncan-field theory, we investigate therate equations of the process with constant reaction rates and obtain the asymptotic descriptions of the cluster-massdistribution. In the case of the same initial concentrations of two species, the scaling descriptions for the cluster-massdistributions of the two species are found to break down completely. It is also observed that the kinetic behaviors ofdistinct species are quite complicated for the case of different initial concentrations of the two species. Tile clusters oflarger initial concentration species (heavy species) possess peculiar scaling properties, while the cluster-mass distributionoflight species has not scaling behavior. The exponents describing the scaling behavior for heavy species strongly dependon its fragmentation rate and initial monomer concentrations of two kinds of reactants....
2020-11-10 09:33:08浏览：40
查看 -
Analysis of Energy Characteristics in the Process of Freak Wave Generation
The energy characteristics in the evolution of the wave train are investigated to understand the inherent cause of the freak wave generation. The Morlet wavelet spectrum method is employed to analyze the numerical, laboratory and field evolution data of this generation process. Their energy distributions and variations are discussed with consideration of corresponding surface elevations. Through comparing the energy characteristics of three cases, it is shown that the freak wave generation depends not only on the continuous transfer of wave train energy to a certain region where finally the maximum energy occurs, but also on the distinct shift of the converged energy to high-frequency components in a very short time. And the typical energy characteristics of freak waves are also given....
2020-11-10 09:33:08浏览：60
查看 -
Simulation on flow process of filtered molten metals
Filtration and flow process of molten metals was analyzed by water simulation experiments. Fluid dynamic phenomena of molten metal cells through a foam ceramic filter was described and calculated by ERGOR equation as well. The results show that the filter is most useful for stable molten metals and the filtered flow is laminar, so that inclusions can be removed more effectively....
2020-11-10 09:33:08浏览：56
查看
