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101.
带扰动观测器的船舶轨迹跟踪自适应动态面滑模控制 总被引:1,自引:1,他引:0
针对遭受未知外部环境扰动的三自由度全驱动船舶轨迹跟踪控制问题,设计一种带扰动观测器的自适应动态面滑模控制方法。该方法构造扰动观测器估计未知扰动,并对控制量进行前馈补偿,采用σ修正泄漏项的自适应律估计扰动观测误差的界以提高控制精度,结合动态面技术解决传统反演法的微分爆炸问题,并选取李雅普诺夫函数证明该控制器可保证闭环系统内所有信号的一致最终有界性。基于一艘供给船舶进行仿真试验,结果表明,所设计的控制器输出合理有效且跟踪精度高,在工程实际中具有一定的参考价值。 相似文献
102.
This paper examines the activity engagement, sequencing and timing of activities for student, faculty and staff commuter groups at the largest university in the Maritime Provinces of Canada. The daily activity patterns of all university community groups are modeled using the classification and regression tree classifier algorithm. The data used for this study are derived from the Environmentally Aware Travel Diary Survey (EnACT) conducted in spring 2016 at Dalhousie University, Nova Scotia. Results show that there are significant differences in activity and travel behavior between university population segments and the general population in the region, and between campus groups. For example, students participate in more recreation activities compared to faculty and staff. They also take more trips to and from campus, and are more flexible in their scheduling of trips. The insights gained from this study will provide helpful information for promoting sustainability across university campuses, and for development of campus-based travel demand management strategies. 相似文献
103.
We present new approaches that expand upon the time geographic density estimation (TGDE) framework previously employed to estimate potential path trees. In the past, TGDE metrics have identified possible locations an individual moving object may have passed between, given known origin and destination points. This paper utilizes a new form of TGDE to investigate taxicab GPS traces over a specified time horizon with position ‘gaps’. To this end, we propose a new extension to the TGDE framework, TGDE-C, which is used to determine the cumulative TGDE values for a group of GPS traces, at a given location. These metrics are applied to multiple taxis and allow for time of day analysis. Additionally, we combine these new extensions with existing TGDE metrics that allow us to determine how accessible individual or groups of vehicles are to urban opportunities. 相似文献
104.
In order to study the diffusion law of grouting slurry in the water-rich sand layer under flowing water conditions, a grouting test model consisting of a main test system, a grouting system, and a measurement system was developed. And for detecting the diffusion scope of the grouts, a new resistivity method was proposed. It is found that the relationship between grouting pressure and grouting rate during the test is strong. Under hydrodynamic conditions, the grouting slurry diffuses elliptically. Due to gravity and the effect of the upper water flow, the center of gravity of the ellipsoid is below the grouting outlet, and the grouting effectively improves the physical and mechanical properties of water-rich sand bodies. At the same time, the resistivity method has a good application effect on the detection of grouting diffusion range. The range of slurry diffusion obtained by the resistivity method is basically consistent with the boundary of the stone body after excavation, indicating that the resistivity method is reliable for detection of grouting range in dynamic water-rich sand layer. © 2018, Editorial Office of "Modern Tunnelling Technology". All right reserved. 相似文献
105.
In order to quantitatively evaluate the safety of the surrounding rock of an underground cavern under seis-mic load, a comprehensive evaluation method for the stability of surrounding rock is proposed based on the general safety factor and point safety factor. A calculation method for the general safety factor of a cavern based on the prin-ciple of shear strength reduction of a rock mass is given, the run-through of the plastic zone between the main power-house and main transformer room is presented as a critical criterion for the overall instability of the cavern, and the general safety factor is obtained by searching for the reduction coefficient. A point safety factor calculation method based on the Mohr-Coulomb yield criterion is given. The influence of different seismic input parameters on the general safety factor of the cavern and the point safety factor of key positions are studied based on an underground power-house cavern of a hydropower station in Southwest China. The results show that the quantitative evaluation method for the stability of the surrounding rock based on the safety factor is feasible and can reflect the general safety de-gree and local safety degree of different positions of the cavern for different working conditions. It is found that the general safety factor of the cavern and the point safety factor of key positions decrease with an increase of the ampli-tude and duration of a seismic wave while they increase with an increase of the incident angle; additionally, the low frequency of a seismic wave has a great influence on the cavern while the high frequency has little effect. © 2018, Editorial Office of "Modern Tunnelling Technology". All right reserved. 相似文献
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108.
针对高压齿轮泵浮动侧板磨损问题,在解析齿轮泵内部流场的基础上重点研究了浮动侧板反推力作用点变化规律和导致侧板产生倾覆力矩的关键因素。以某型号高压大排量齿轮泵为模型,运用CFD软件解析齿轮泵内部流场并根据侧板结构特点建立压紧力和反推力的求解微分方程,求得一个轮齿啮合周期内的侧板倾覆力矩变化规律,同时通过建立齿轮泵工作腔压力测试系统对该理论分析结果进行验证,额定工况下:试验值与理论值误差为4.18%,当轮齿转角φ=14°时倾覆力矩达到最大值Ms=82.16N?m。该研究为高压大排量齿轮泵浮动侧板倾覆力矩计算和侧板结构优化设计提供了理论基础和技术支撑。 相似文献
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110.
交通事故侦测中占有率的改进灰色预测 总被引:3,自引:0,他引:3
在交通事故侦测的统计预测算法中引入灰色理论的实践证明,灰色预测是占有率短期预测的可行方法,同时二重估计改进的预测方法可合理地提高交通事故预测的准确性。 相似文献