Aiming to reduce the thick cloud interference in target detection, this paper proposed a thick cloud region detection method based on double scale ocean background Gauss model for large scale high resolution ocean remote sensing images. Firstly, the paper analyzed the statistical characteristics of seawater background and thick cloud with Haar wavelet decomposition principle, and it found they are distinct in different scales. Secondly, this paper established a double scale Gauss model for seawater background and give its parameters estimation method. Finally, the thick cloud region detection method is put forward based on seawater background model. Experimental results show that our proposed method can detect thick cloud regions effectively.
Abstract For the change of uncertainty caused by the influence of time on the bolt connection during use, this paper is based on a time-varying uncertainty design method for several parameters that change with time. The method consists of stochastic differential equations. The bolt-on time-varying design combines mathematical models of the distribution parameters of multivariate random variables. The design method of bolting connection with uncertainties of various influencing factors with time is proposed, and the time-varying design of tightly connected bolts subjected to axial working load is taken as an example. The method considers the dynamic changes of the stress and the allowable stress of the bolted joint, so that the safety of the bolted product is more accurately evaluated for dynamic reliability. Through this method, combined with the set initial values of the parameters and the historical data obtained by the test, the reliability of a certain time can be calculated. The design of the example uses Matlab to simulate the data, and the reliability of the specified time is obtained, which is the test of the bolting result. And assessment provides an important reference.
Flow and heat transfer are two very complex physical processes in plastic injection molding. Using CAE technique, the mold design can be analyzed and simulated in computer to replace the actual mold trial-and-error and potential defect can be predicted and corrected before mold is made. Theories of numerical analysis are introduced and how to use the CAE results to optimize injection mold delivery and cooling system design with some typical examples is illustrated.
Abstract Ultra-fine 2,2’,4,4’,6,6’- Hexanitrostilbene (HNS-IV) was obtained by HNS-II by vibration cavity comminute. This method uses only alcohol and deionized water, which can be viewed as a green technology. The morphology, particle size, specific surface area, thermal decomposition property and the threshold energy for slapper detonator were compared between HNS-IV and HNS-II in this paper. Results show that after HNS pulverizing, the particle size decreased from 27.18μm to 1.44μm, the specific surface area increased from 0.73m 2• g −1 to 9.10m 2• g −1 . DSC analysis shows that the decomposition peak temperature T d decreases and the melting temperature T m increases after pulverizing. It is speculated that in the explosive reaction with very high heating rate, the enthalpy of decomposition will be increased by pulverizing, which will be more conducive to detonation growth and explosive reaction. According to the calculation of thermal decomposition kinetics, the decomposition and activation energy Ea of HNS decreases after pulverizing, and the thermal decomposition reaction rate of HNS-IV increases when the temperature is less than 409.6°C. The initiation threshold test of the impact plate shows that the 50% initiation threshold energy of HNS- II is 1.242J, and the 50% initiation threshold energy of HNS-IV is 0.558J, and the initiation threshold for slapper detonatorer is significantly reduced by 55%. This means that the ultra-fine HNS-IV is very suitable as the main ingredient in the booster in the EFI initiation.
Abstract Sink mark is one of the flaws occurring on the surface of injection-molded parts caused by inappropriate mold design and process parameters. Sink marks are often quite visible and significantly impair the surface quality of the parts. In this reports, an L27(313) experimental matrix designed based on the Taguchi method was conducted to investigate the effect of process parameters and two-way interactions on sink mark depth of injection molded parts, and to minimize the sink mark depth. The relative significance of each processing parameter on the sink marks was analyzed using analysis of variance (ANOVA) and F-test. A plate cavity with bosses of various thicknesses was used in the investigation. Experiments were carried out on a CJ80E II injection-molding machine, and sink mark depths were measured by a movable bridge 3D COMERO. For the factors and interactions selected in the main experiments, the boss thickness and melt temperature were found to be the principal factors affecting sink mark formation in injection-molded parts. Experimental investigation can help to understand the formation mechanism of sink marks, and to optimize the surface quality of injection-olded parts. Keywords: Design of experimentInjection moldingProcess optimizationSink markTwo-way interaction 5. ACKNOWLEDGMENTS The authors would like to express their gratitude to the National Engineering Research Center for Advance Polymer Processing Technology of Zhengzhou University in China, for the funding support of 'Major Research Plan of National Natural Science Foundation of China (10590352)' and 'General Program of National Natural Science Foundation of China (10372095)'.
At present, the dynamic modeling methods of elastic aircraft mainly include two kinds: mean axis method and quasi-axis method. The two methods have their own advantages and disadvantages, and there are few articles on the comparison of the two methods. In this paper, based on the Lagrangian equation of energy theory, the modeling methods of the mean axis system and the quasi-axis system are derived, and the elastic models obtained from the quasi-coordinate system and the mean axis system are compared and analyzed. The correctness of the hypotheses is verified by numerical calculation according to the hypothetical conditions, which lays a solid foundation for the further study of aeroelastic modeling.
English teaching in higher vocational schools is experiencing great changes.Training of oral English and the development of foreign language communicative ability have been valued day by day.The author applies task-based teaching in oral English classroom in higher vocational and technical colleges and tries to find an effective teaching model for oral English teaching.The research belongs to experimental study on teaching methods.The task-based teaching model adopted is easy to be applied in practical teaching.
The adhesion and growth of human periodontal ligament cells (PDLC) on collagen (Col), hyaluronic acid (HA) and HA/Col scaffolds were studied to evaluate the feasibility of HA/Col as a scaffold material in periodontal tissue engineering.Human PDLC cultured in vitro was collected and seeded on Col, HA, HA/Col scaffolds crosslinked by carbodiimide. The influences of scaffolds on cell adhesion and growth were observed by MTT assay. The growth of human PDLC on scaffolds was observed through inverted phase contrast microscope and scanning electron microscope (SEM).The result of MTT assay demonstrated that except the seventh day there was obviously differentiation between each group Col, HA, HA/Col scaffolds at the first, second and fourth day, and HA/Col group was higher than control group all the time. Human PDLC successfully grew on scaffolds.HA/Col scaffold was more suitable for human PDLC adhesion compared with Col scaffold and HA scaffold. This indicates that HA/Col scaffold might be a potential ideal candidate for periodontal tissue engineering.
In comparison with CK,NPKM increased soil total P content by 52.2%,and that in the treatment of NPK+straw increased by 18.85%,NP,PK and NPK treatment increased by 17.87%,15.88% and 14.89%,respectively.Above soil total P increases were also higher than those with the treatment of N only or NK.Compared with CK,soil available P increased by 10-fold and 3-fold with the treatment of NPKM and NPK+straw,and 3-5 fold with NP,PK and NPK.Therefore,application of chemical fertilizer alone without organic manure can keep the balance of K input and output.Addition of NPK along with pig manure and straw increased soil available K by 16.0% and 11.4% respectively,compared with CK.The available K declined year by year in the treatments without K fertilizer.Changes of soil slow-released K followed similar trend to the available K.Therefore,long-term application of chemical K fertilizer or its combined application with organic materials can not only meet the K demand by crops.
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