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工程上常将永磁体分段来减小自身涡流损耗,减小高温退磁的风险。现有永磁体分段的转子涡流损耗解析模型大多忽略涡流反作用影响,应用于高速永磁电机转子涡流损耗计算会造成较大误差。本文基于子域法提出了一种针对永磁体周向分段的高速永磁电机转子涡流损耗解析方法。在考虑定子开槽和各次电流谐波影响的基础上,通过引入考虑各次谐波透入深度的衰减系数对涡流密度进行修正,进而考虑涡流反作用的影响。基于该解析模型,分析了电枢磁场中转子涡流损耗随永磁体分段数的变化规律。将有限元仿真计算结果与解析结果对比,验证解析模型的正确性。 相似文献
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相对于固定式风机,海上浮式风力机系统的结构与受到的环境载荷更为复杂。为模拟其动力响应,选择合理的动力学建模方法致关重要。本文以OC4-NERL5MW浮式风力机为例,分别建立浮式风机系统的单刚体动力学模型与刚-柔耦合动力学模型,对比研究2种模型在计算浮式风机系统动力响应的差异。结果表明,2种模型在较高工况的运动标准差有一定差别,其他情况的运动响应及气动转矩的均值和标准差差别都不大。刚体模型有更高的计算效率,可用于设计初始阶段浮式风机系统的动力学参数及方案筛选的大规模计算;刚柔耦合模型有更高的计算精度,可用于后续的动力学参数精细校核。 相似文献
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为解决船体分段任务包工时定额的计算过度依赖线性公式而忽略工时定额与工艺参数之间的非线性关系的问题,提高工时定额计算的效率和精确度,将PSO-BP神经网络技术应用到船体分段任务包工时定额中。通过对影响船体分段中间产品额定工时的工艺参数进行分析,建立多输入单输出的PSO-BP神经网络模型,并应用实际数据对PSO-BP神经网络进行训练,测试仿真结果与实际值之间的误差在允许范围内。验证结果表明,采用PSO-BP神经网络建立船体分段任务包工时定额模型,能对任务包作业工时进行准确预测。 相似文献
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Cline Laurent Paul Tett Teresa Fernandes Linda Gilpin Ken Jones 《Journal of Marine Systems》2006,61(3-4):149
Despite a tendency for the complexity of physical–biological models to increase, simple coupled models remain useful for some applications and can provide insights into crucial links between physical and biological processes. This argument is illustrated with an account of a simple 3-box model intended to help assess the capacity of fjords to assimilate nutrients from fish farms. The model, a dynamic version of the UK “Comprehensive Studies Task Team” (CSTT) steady-state model for eutrophication, was applied to Loch Creran (Scottish Western Highlands) and was implemented using Stella 8 and tested using historical data from 1975 (before the installation of a salmon farm) and field data collected in 2003, during the period of operation of the farm. The model's biological state variables are chlorophyll, dissolved inorganic nitrogen (DIN) and dissolved inorganic phosphorus (DIP), and it includes a simple run-off model to convert rainfall into river discharge. The physical processes involved in exchange between the loch and the adjacent waters of the Firth of Lorne were parameterised as a constant daily exchange rate.Between 1975 and 2003, local inputs of nutrient increased but, despite this, there was little apparent increase in nutrient concentrations in the loch, and observed chlorophyll concentrations decreased substantially. Model simulations of chlorophyll and DIN agreed well with observations in 1975, as did DIN simulations in 2003. However, simulated chlorophyll was overestimated in 2003.Some of the agreement between observations and simulations come from the use of observed boundary conditions to force the model. However, even when boundary conditions are subtracted from simulations and observations, the simulations in most cases retain a significant correlation with observations, demonstrating that the model's ‘interior’ processes do add to its ability to replicate conditions in the loch. 相似文献
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采用C 建立了港口前沿作业系统的计算机仿真模型,确定了仿真模型边界、假设条件;对于不同到港船型到港时间序列的处理作了阐述,并对程序和模型的正确性进行了检验。对港口前沿作业系统的一些直接因素对于仿真结果的影响作了敏感性分析,考察随装卸能力和泊位数变化的待泊时长这个关键量化指标的变化。最后对仿真结果进行了分析并提出一些有益的结论。 相似文献
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本文利适合涌浪计算的二维非恒定流数学模型.对电站机组紧急关闭产主的涌浪运动进行的数值模拟.从数值成果看出.电站紧急关闭产生的涌浪的水面升降激烈.波陡大.具有一定的破坏性.在文章的未尾.给出了这种涌浪的计算公式.供有关部门参考. 相似文献
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Hang Tuah. Salim 《水道港口》2010,31(5):321-321
Belawan is the largest port serving North Sumatra for the import and export.Port has facilities for handling container,CPO liquid bulk cargo,Oil,and other agriculture products.Its location is at the river mouth which is subjected to the heavy sedimentation especially after many deforestation activities in its catchment area. The numerical modeling was developed for predicting the rate of sediment caused by erosion in the catchment area for several scenarios.This predicted rate of sediment was applied as input to model of sedimentation in the ocean.Present condition of sedimentation data was used as calibrated data.This integrated model was used to simulate the sedimentation in Belawan access channel and harbor basin for several development plans. 相似文献
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A new coupled ice–ocean ecosystem model that links the pelagic and ice ecosystems was used to clarify the role of ice algae in ice-covered ocean ecosystems. The model was applied to Lake Saroma (Hokkaido, Japan) in 1992. Comparison of the model's results with observational data confirmed that the model reproduced the behavior of the ecosystem with acceptable accuracy during the period from winter to spring. The primary production of the ice algae is effectively transported into the pelagic system by means of physical releasing effects: brine convection, ice melting and freezing, and diffusion generated at the bottom of the ice. Ice algae released from the ice are rapidly exported because of their high sinking speed and the shallow depth of Lake Saroma. For this reason, the zooplankton in Lake Saroma cannot graze these released algae. However, zooplankton actively graze the ice algae living along the bottom of the ice. These results show that, before their release, ice algae play an important role as a food source for overwintering zooplankton. A sensitivity analysis revealed a positive correlation between the sinking speed of the released ice algae and the magnitude of the spring bloom by pelagic phytoplankton, and that the time when secondary production becomes active is an important factor in the linkage between these two algal populations. 相似文献
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