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排序方式: 共有97条查询结果,搜索用时 296 毫秒
1.
This paper presents a new particle swarm optimization (PSO) algorithm to optimize the trajectory of morphing-wing missile so as to achieve the enlargement of the maximum range. Equations of motion for the two-dimensional dynamics are derived by treating the missile as an ideal controllable mass point. An investigation of aerodynamic characteristics of morphing-wing missile with varying geometries is performed. After deducing the optimizing trajectory model for maximizing range, a type of discrete method is put forward for taking optimization control problem into nonlinear dynamic programming problem. The optimal trajectory is solved by using PSO algorithm and penalty function method. The simulation results suggest that morphing-wing missile has the larger range than the fixed-shape missile when launched at supersonic speed, while morphing-wing missile has no obvious range increment than the fixed-shape missile at subsonic speed. 相似文献
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《Applied Thermal Engineering》2014,62(2):732-737
Effects of nano-Ag with high thermal conductivity on the combustion wave behavior of Al–CuO MIC (metastable intermolecular composite) are studied in this paper by incorporating Al–CuO MIC with nano-Ag particles in different weight proportions. The physical and chemical characteristics of Al–CuO MIC are determined using scanning electron microscope (SEM), X-ray diffraction (XRD) and differential scanning calorimeter (DSC). The combustion wave behavior is identified by high-speed video recording (HSVR). The experimental observations confirm that the presence of nano-Ag particles improves the heat transfer efficiency. With nano-Ag increasing from 1 wt% to 10 wt%, the first exothermic peak temperature decreases from 607.8 °C to 567.6 °C, and average combustion speed (ACS) increases at first and then reduces. The most suitable amount of nano-Ag is 2 wt% with the ACS and instantaneous combustion velocity on the order of 954.0 m/s, 1562.5 m/s. Moreover, heat transfer mechanisms in the combustion process of Al–CuO MIC are better understood, especially by distinguishing conduction from convection during the combustion propagation. Furthermore, three stages (ignition, acceleration and steady combustion) of reactive propagation are observed in the combustion process. And the corresponding dominative heat transfer mechanisms in the three stages are conduction, conduction to convection transition, and convection, respectively. 相似文献
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《Ceramics International》2017,43(13):9941-9944
Zr-codoped 0.5 at% Eu: (Y0.9La0.1)2O3 ceramics sintered in H2-reducing atomsphere, together with the ceramics with annealing treatment, were fabricated by solid-state reactions and the effects of Zr codoping on these materials’ photoluminescence examined. The obtained emission spectra showed that Zr codoping adjust the materials’ photoluminescence with UV excitation and a logical explanation was proposed. The results suggested that an Eu-doped, yttrium-lanthanum oxide transparent ceramic with Zr in low concentration appeared to have promising potential in modern lighting applications. 相似文献
5.
《Measurement》2016
This work presents the design of a MEMS accelerometer that is specifically intended for Structural Health Monitoring (SHM) applications where sensing low frequency low amplitude accelerations with high resolution is essential. The surface micromachined comb drive capacitance accelerometer structure has been considered in this design. The simulation experiments conducted on these devices using IntelliSuite MEMS design tool show that it has excellent displacement sensitivity of 21.39 μm/g, a capacitive sensitivity of 1.22 pF/g and voltage sensitivity of 1783 mV/g/V when it is designed to measure 0–0.1 g. Further, it is seen that it has a very low noise floor of 1.32 μg/√Hz and therefore high resolution. Since the accelerations can be as low as 0.04 g in SHM applications, excellent resolution is the primary goal in this design. Further, one more sensor specifically meant for strong motion seismic application has also been reported. This device has a bandwidth of 0–250 Hz and a noise floor of 5.612 μg/√Hz in addition to a sensor level voltage sensitivity of 97.9 mV/g/V. Finally, the comparison of these results with other similar devices reported in the past clearly illustrates the comparable performance of the present devices. Further, these devices, unlike the commercial low frequency accelerometers and other similar devices reported in the past can be fabricated by surface micromachining and CMOS compatible processes. 相似文献
6.
《Fusion Engineering and Design》2014,89(4):442-455
The first detailed Computational Fluid Dynamics (CFD) analysis of the FW06 panel of the ITER shielding blanket is presented in two companion papers. In this Part I we introduce the problem, define the model together with its input and discuss the results with particular reference to the hydraulics of the water coolant. The pressure drop across the panel is computed, together with the distribution of the flow among the different channels. Different design options are studied, with particular reference to the minimization of stagnation/recirculation regions. 相似文献
7.
The mesoscale characteristics of granular metal mixtures have considerable influence on their shock compression properties. However, it is difficult to use traditional research methods, such as theoretical analysis and experiments, to investigate granular metal mixtures in mesoscale. In this study, a mesoscale simulation method, which follows the real morphology distribution, is introduced to investigate the shock compression behaviour of granular metal mixtures based on the mesoscale characteristics. Numerical studies on the compressive processes of typical granular metal mixtures were conducted in mesoscale. The relationship between particle velocity (Up) and shock velocity (Us), which is the bridge between mesoscale and macroscale, is established and validated against the experimental results. The influence of mesoscale characteristics of an Al–W-Binder granule metal mixture on the shock compression behaviour has been analyzed based on the simulation results. It has been shown that the simulation results correlate reasonably well with the corresponding experimental results. The numerical studies presented can be used to predict dynamic response of granular metal mixtures with different mesoscale characteristics over a wide range of pressure. 相似文献
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张荣 《太赫兹科学与电子信息学报》2010,8(4):476-479
为了解决测控系统软件开发中LabVIEW的数据库与报表程序的设计问题,介绍了利用第三方数据库开发工具在LabVIEW中实现数据库的编程技术。讨论了基于LabVIEW与Delphi混合编程的报表设计技术,采用这种混合编程设计技术,简化报表编程,快速设计出标准、灵活多样的报表。工程应用表明,利用这些技术可解决大部分测控系统开发中有关数据库与报表的设计问题。 相似文献
10.
Postbuckling, nonlinear bending and nonlinear vibration analyses are presented for single-wall carbon nanotubes (SWCNTs) resting on a two-parameter elastic foundation in thermal environments. The SWCNT is modeled as a nonlocal nanobeam which contains small scale effects. The elastomeric substrate with finite depth is modeled as a two-parameter elastic foundation. The thermal effects are included and the material properties of both SWCNTs and the substrate are assumed to be temperature-dependent. The governing equation that includes beam–foundation interaction is solved by a two-step perturbation technique. The numerical results reveal that the small scale parameter e0a reduces the postbuckling equilibrium paths, the static large deflections and natural frequencies of SWCNTs resting on an elastic foundation. The results also reveal that the effect of the small scale parameter is significant for compressive buckling, but less pronounced for static bending and marginal for free vibration of SWCNTs resting on an elastic foundation. 相似文献