Based on the problem of simulation and prediction of the non-equidistant raw data series for the multi-variable with interaction, the multi-variable MGM(1,�� ) model in the case of non-equidistance is modeled and the non-equidistance MGM(1,�� ) model is constructed in order to improve the accuracy of simulation and prediction. The simulation and prediction accuracy is proved to be higher in multi-variable non-equidistant MGM(1,�� ) model than in single-variable non- equidistant GM(1,1) models according to an application. The proposed model is suitable in non-equidistant modeling and equidistant modeling, thus, non-equidistant model has broad applying value.
The thermal fatigue and high temperature oxidation resistance of SKH51 steel and 65Mn steel were studied by circularly heating and cooling the samples in the aluminum die-casting die working temperature range(20～700 ℃).The results show that the microstructure of SKH51 has no significant change,an obvious oxidation layer is formed on the surface of 65Mn sample.SKH51 steel with high contents of chromium and tunstgen has better oxidation resistance at elevated temperature than that of 65Mn.The high temperature oxidation relative quality loss of 65Mn is hundreds times larger than that of SKH51.There are no thermal fatigue cracks on the surface of SKH51 and 65Mn samples with small diameter and simple configuration.SKH51 steel can be used for making the die-casting die core,but 65Mn steel can not be used.
Carbon dioxide hydrate were produced from the anionic surfactant——Sodium Laurate water solutions of 0.000,0.016,0.021,0.026 mol/L to investigate the effect of surfactant on gas hydrate formation in a quiescent system.The results show that Sodium Laurate can markedly promote gas-hydrate growth and hydrate formation rate increases with Sodium Laurate concentration,but when Sodium Laurate concentration above critical micellar concentration(CMC),the increase in Sodium Laurate concentration will have little effect on promotion of gas hydrate formation rate.
Under the condition of normal steel's hot rolling,optimizing temperature distribution of reheating furnace is an effective way to reduce the reheating energy consumption and it obtains the better product quality.Aiming at the defects of previous methods for temperature setting,an improved optimal algorithm for furnace's temperature distribution was proposed on the base of analyzing the reheating object and reheating mechanism.The simulation results show that the method is effective.
A comparative study of personality with Eysenck Personality Questionnaire,is carried out among 20% students in the natural classes with the top and the last of average grade points respectively.The target is 1319 undergraduates from freshman to junior in Dongguan University of Technology.The result shows that students with different grade points have some personality differences,in which the P scale scores of the 20% top students is significantly lower than that of the 20% last students,while the L scale scores the 20% top students is significantly higher than the scores of the 20% last students.
A novel method for selective bromination of graphene was proposed. The reduced graphene oxide (denoted as graphene) used as the raw material, was brominated with 1,3-dibromo-5,5-dimethylhydantoin in the mixture of trifluoromethanesulfonic acid and CH2Cl2 at room temperature. The success of bromination was confirmed by x-ray photoelectron spectroscopy, scanning electron microscopy, energy dispersive x-ray analysis, and Fourier transform-infrared spectroscopy. Moreover, it was found that the bromine concentration of the brominated graphene increased up to 10% Br/C with increasing bromination duration for the first 24 h; then the concentration unexpectedly decreased. The brominated graphene was further functionalized with 4-pyridinyl boronic acid through the Suzuki-coupling reaction. The atomic concentration of Br greatly decreased, whereas the atomic concentration of N increased significantly. This indicated that the functionalization was successful. This proposed bromination method is easy and well-suited for graphene and its derivatives. Additionally, the brominated graphene can be a starting material for constructing other graphene-based functional materials.
The stochastic simulation method,based on the concept of control window and the numerical solution of the Langevin equation,is applied to solve the deposition problem of particles from the flowing suspensions onto a fiber collector. Using the Kuwabara model to characterize the flow field,the effects of Stokes number,interception parameter,packing density,particle size distribution on the collection efficiency,and the deposition morphology of particles onto a collector are examined. The morphology of deposit obtained in the simulated results agrees well with experimental observations. The estimation of the initial collection efficiency through the simulations considers that the deposited particles are in good agreement with published experimental data. In addition,the collection efficiency of particles increases in a wider particle size distribution region.
The theory of Just in Time Distribution(JITD) is applied into the distribution network design.By coordinating the whole inventory of network,considering the punctuality and stability of distribution,a model of Integrated Location Routing and Inventory Problem(ILRIP) is built on the condition that the demand is fixed and there are many distribution centers and customers from the perspective of integrated logistics,then a bi-level algorithm of Particle Swarm Optimization(PSO) is designed to solve it.At the end of this paper,a numerical example is given.The conclusion will help to optimize the logistics distribution network,so as to improve the reliability of quick response and the customer service level,as well as reduce cost.
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