为了解决无电、无网络情况下井下人员逃生定位和救援导航的难题,架构了井下地磁与RFID射频结合的井下定位方法 GRPM(Geomagnetic and Radio Positioning Method)。分析了井下巷道地磁数据带状连续、区域易突变的特点,选取地磁平均值、...为了解决无电、无网络情况下井下人员逃生定位和救援导航的难题,架构了井下地磁与RFID射频结合的井下定位方法 GRPM(Geomagnetic and Radio Positioning Method)。分析了井下巷道地磁数据带状连续、区域易突变的特点,选取地磁平均值、标准差、峰态系数、粗糙度适配性指标,进行典型巷道区域的适配性评价。在适配区内开展均方差相关(MSD)、归一化积相关(NPROD),以及基于Hausdorff距离相关(HD)的定位匹配对比试验和基于等值域匹配的效果分析。试验结果表明:标准差、粗糙度指标适合巷道定位适配性评价,分析准确。基于1~2倍等值域的NPROD匹配模型适合井下人员动态行走定位,匹配速度较快,满足精确定位要求。展开更多
The uniaxial perfectly matched layer (PML) method uses rectangular domain to define the PML problem and thus provides greater flexibility and efficiency in deal- ing with problems involving anisotropic scatterers.In t...The uniaxial perfectly matched layer (PML) method uses rectangular domain to define the PML problem and thus provides greater flexibility and efficiency in deal- ing with problems involving anisotropic scatterers.In this paper an adaptive uniaxial PML technique for solving the time harmonic Helmholtz scattering problem is devel- oped.The PML parameters such as the thickness of the layer and the fictitious medium property are determined through sharp a posteriori error estimates.The adaptive finite element method based on a posteriori error estimate is proposed to solve the PML equa- tion which produces automatically a coarse mesh size away from the fixed domain and thus makes the total computational costs insensitive to the thickness of the PML absorb- ing layer.Numerical experiments are included to illustrate the competitive behavior of the proposed adaptive method.In particular,it is demonstrated that the PML layer can be chosen as close to one wave-length from the scatterer and still yields good accuracy and efficiency in approximating the far fields.展开更多
The application of multi-hull ship or trimaran vessel as a mode of transports in both river and sea environments have grown rapidly in recent years.Trimaran vessels are currently of interest for many new high speed sh...The application of multi-hull ship or trimaran vessel as a mode of transports in both river and sea environments have grown rapidly in recent years.Trimaran vessels are currently of interest for many new high speed ship projects due to the high levels of hydrodynamic efficiency that can be achieved,compared to the mono-hull and catamaran hull forms.The purpose of this study is to identify the possible effects of using an unsymmetrical trimaran ship model with configuration（S/L） 0.1-0.3 and R/L=0.1-0.2.Unsymmetrical trimaran ship model with main dimensions： L=2000mm,B=200 mm and T=45 mm.Experimental methods（towing tank） were performed in the study using speed variations at Froude number 0.1-0.6.The ship model was pulled by an electric motor whose speed could be varied and adjusted.The ship model resistance was measured precisely by using a load cell transducer.The comparison of ship resistance for each configuration with mono-hull was shown on the graph as a function of the total resistance coefficient and Froude number.The test results found that the effective drag reduction could be achieved up to 17% at Fr=0.35 with configuration S/L=0.1.展开更多
文摘为了解决无电、无网络情况下井下人员逃生定位和救援导航的难题,架构了井下地磁与RFID射频结合的井下定位方法 GRPM(Geomagnetic and Radio Positioning Method)。分析了井下巷道地磁数据带状连续、区域易突变的特点,选取地磁平均值、标准差、峰态系数、粗糙度适配性指标,进行典型巷道区域的适配性评价。在适配区内开展均方差相关(MSD)、归一化积相关(NPROD),以及基于Hausdorff距离相关(HD)的定位匹配对比试验和基于等值域匹配的效果分析。试验结果表明:标准差、粗糙度指标适合巷道定位适配性评价,分析准确。基于1~2倍等值域的NPROD匹配模型适合井下人员动态行走定位,匹配速度较快,满足精确定位要求。
文摘The uniaxial perfectly matched layer (PML) method uses rectangular domain to define the PML problem and thus provides greater flexibility and efficiency in deal- ing with problems involving anisotropic scatterers.In this paper an adaptive uniaxial PML technique for solving the time harmonic Helmholtz scattering problem is devel- oped.The PML parameters such as the thickness of the layer and the fictitious medium property are determined through sharp a posteriori error estimates.The adaptive finite element method based on a posteriori error estimate is proposed to solve the PML equa- tion which produces automatically a coarse mesh size away from the fixed domain and thus makes the total computational costs insensitive to the thickness of the PML absorb- ing layer.Numerical experiments are included to illustrate the competitive behavior of the proposed adaptive method.In particular,it is demonstrated that the PML layer can be chosen as close to one wave-length from the scatterer and still yields good accuracy and efficiency in approximating the far fields.
基金supported by the Directorate for Research and Community Service,University of Indonesia(RUUI Utama 2012),Jakarta,Indonesia
文摘The application of multi-hull ship or trimaran vessel as a mode of transports in both river and sea environments have grown rapidly in recent years.Trimaran vessels are currently of interest for many new high speed ship projects due to the high levels of hydrodynamic efficiency that can be achieved,compared to the mono-hull and catamaran hull forms.The purpose of this study is to identify the possible effects of using an unsymmetrical trimaran ship model with configuration（S/L） 0.1-0.3 and R/L=0.1-0.2.Unsymmetrical trimaran ship model with main dimensions： L=2000mm,B=200 mm and T=45 mm.Experimental methods（towing tank） were performed in the study using speed variations at Froude number 0.1-0.6.The ship model was pulled by an electric motor whose speed could be varied and adjusted.The ship model resistance was measured precisely by using a load cell transducer.The comparison of ship resistance for each configuration with mono-hull was shown on the graph as a function of the total resistance coefficient and Froude number.The test results found that the effective drag reduction could be achieved up to 17% at Fr=0.35 with configuration S/L=0.1.
