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1.
This research is concerned with the problem of 4 degrees of freedom (DOF) ship manoeuvring identification modelling with the full-scale trial data. To avoid the multi-innovation matrix inversion in the conventional multi-innovation least squares (MILS) algorithm, a new transformed multi-innovation least squares (TMILS) algorithm is first developed by virtue of the coupling identification concept. And much effort is made to guarantee the uniformly ultimate convergence. Furthermore, the auto-constructed TMILS scheme is derived for the ship manoeuvring motion identification by combination with a statistic index. Comparing with the existing results, the proposed scheme has the significant computational advantage and is able to estimate the model structure. The illustrative examples demonstrate the effectiveness of the proposed algorithm, especially including the identification application with full-scale trial data. 相似文献
2.
A recent paper by Çimen and Banks [2004. Nonlinear optimal tracking control with application to super-tankers for autopilot design. Automatica, 40(11), 1845–1863] on optimal control system design for oil tanker propulsion and heading highlighted the importance of accurately representing the dynamics of such a vessel. Results presented in that paper are based on a simulation model that provides unrealistic results for an oil tanker of the size considered. Therefore, the results obtained from the simulated ship control problem are not representative of the physical system being considered. In this communication an alternative, more realistic model is presented and discussed with reference to the original publications that define the ship model dynamics. 相似文献
3.
Until recently, numerical simulations of discontinuities in highly super-Alfvénic plasmas have been severely limited by comparatively crude resolution and accuracy. Significant progress in the numerical simulation of such plasmas was achieved with the recently implemented Central Weighted Essentially Non-Oscillatory (CWENO) scheme. Combining this technique with that of adaptive mesh refinement (AMR), we have developed a third-order numerical scheme, which is able to efficiently capture strong gradients on spatial scales being small compared to the overall scale of the plasma system considered. Here, we first describe important algorithmic aspects of the scheme as well as the physics included in it. Second, we present the results of various performance tests. And, third, we illustrate its application to ‘real world problems’ using the example of the dynamics of a Sedov-type explosion. 相似文献
4.
Comparative studies on Ar and He closed-cycle MHD power plants combined with fossil fuel are performed. The sizes of a regenerative heat exchanger and a boiler are expected to be smaller for He than for Ar. The pressure loss of a working gas in a regenerative heat exchanger is reduced for He. The purification subsystem for He is expected to be more compact and economical than that for Ar; but a larger compressor is required for He than for Ar. 相似文献
5.
采用Cr_(25)Al_5合金进行煤渣/种子条件下静态腐蚀试验(温度1373-1573k,时间50-150hr),试验后得出三种温度下腐蚀重量变化与腐蚀时间的关系,并借助金相显微镜、扫描电镜和俄歇分析进行有关形貌及成份分析,试验表明,温度是材料腐蚀的主要因素,在1473k条件下材料的抗蚀性最好,Al、Si元素在腐蚀过渡层中富集,Cr元素变化不大,但有从基体向外扩散的趋势。由此,这一材料若能进一步改进,可望在控制壁面温度的半热壁型通道中进行试验研究。 相似文献
6.
The durability of a cold wall MHD generator consisting of metal electrodes and alumina-coated peg insulators was experimentally examined in the oil-fired MHD condition with the additive of SO2 corresponding to S = 0.54 wt%. The structure of the electrode wall and various anode and cathode materials were tested, with particular reference to developing long-life electrodes. It was clarified that Pt, SHOMAC (28.8 Cr−1.9 Mo) and SUS-304 as anodes and W---Cu (70 W−30 Cu) and WC---Ag (60 WC−40 Ag) alloys as cathodes were promising for durability and that the structure of an anode divided into two elements connected to each other with an SnO2 resistor was very useful for uniformity of the anode corrosion pattern and the inter-anode voltages. It is reasonable to expect, from the test results, that the lifetime of a cold wall MHD generator in an oil-fired commercial plant will be over 4000 h, and therefore, a foundation for its commercial use has been established. 相似文献
7.
三峡永久船闸工程混凝土表面缺陷处理技术 总被引:1,自引:0,他引:1
三峡永久船闸混凝土缺陷处理是严格按照标准要求进行的,处理前的混凝土缺陷素描是其中的一个重要组成部分,对查清缺陷的数量、分布、性质起到了重要作用。在此基础上制定的处理原则及分区,使混凝土缺陷处理工作做到了有的放矢、重点突出。在处理过程中采用了大量的新工艺、新材料,施工质量良好。 相似文献
8.
Stability of large-scale coal-fired MHD channels is studied by (1) linearized stability analysis, and (2) time-dependent 1-D analysis. The channel length is 15 m with 600 electrode pairs, and the output power ranges from 220.6 MW through 258.7 MW. Linearized stability analyses show that the Faraday channels operated with fixed loading resistance are stable, whereas the two waves of u and u–a (u, a: gas and sound velocity) become unstable in the Faraday channel with fixed loading factor. Two waves of u and u–a are unstable in the diagonal channel with fixed loading current and the u + a wave becomes unstable in the diagonal channel with fixed electrode current. Time-dependent one-dimensional analyses indicate that the Faraday channels with fixed load resistance are smooth without growth of fluctuation. The diagonal channels with fixed electrode current are smooth with no fluctuation, though the linear theory indicates that the u + a wave is unstable. The diagonal channel with fixed load current suffers large disturbance along the latter half of the channel, being consistent with the linearized analysis which indicates that the u - a and u waves are unstable. 相似文献
9.
The potential of ozone for disinfection of ships’ ballast water was investigated using Bacillus subtilis spores as an indicator. The effects of pH, presence of iron, and bacterial strain on disinfection efficacy in seawater, under simulated ballast conditions, were investigated. Ozone dosages of 9 mg/L (pH 7) and 14 mg/L (pH 8.2) and 24 h contact achieved a 4-log inactivation with the various oxidant residuals formed. Iron surface at a ratio to water of 9 m2/m3 impaired the oxidant residuals and the disinfection of spores. Different strains of B. subtilis resulted in different CT values. Ozone does not seem to be a good choice for the control of spore-forming organisms in ballast water, but may be suitable for the control of other species. 相似文献
10.
采用Al2O3基料,添加第二相(ZrO2,Si3N4)和纤维相(ZrO2,(f),以热压法制成Al2O3-Si3N4-ZrO2多相复合材料。研究表明,新材料在青静态和动态试验中表现出良好的综合性能:1073K时的高温电阴率p=1.24×17^7Ω.cm;静态熔渣最大腐蚀速率Vs=0.16μm/h;动态最大腐蚀速率Vd=0.449μm/h。与Al2O3陶瓷相比,室温抗弯强度提高93%,抗热震临界... 相似文献