A SIMPLE PROOF OF THE CHAOTICITY OF SHIFT MAP UNDER A NEW DEFINITION OF CHAOS

Recently, Du has given a new strong definition of chaos by using the shift map. In this paper, we give a proof of the main theorem by constructing a dense uncountable invariant subset of the symbol space E2 containing transitive points in a simpler way with the help of a different metric. We also provide two examples, which support this new definition.

Adaptive Mapping Generalized Space Shift Keying Modulation

Generalized Space Shift Keying (GSSK) modulation is a low-complexity spatial multiplexing technique for multiple-antenna wireless systems. However, effective transmit antenna combinations have to be preselected, and there exist redundant antenna combinations which are not used in GSSK. In this paper, a novel adaptive mapping scheme for GSSK modulation, named as Adaptive Mapping Generalized Space Shift Keying (AMGSSK), is presented. Compared with GSSK, the antenna combinations are updated adaptively according to the Channel State Information (CSI) in the proposed AMGSSK system, and the performance of average Symbol Error Rate (SER) is reduced considerably. In the proposed scheme, two algorithms for selecting the optimum antenna combinations are described. The SER performance of AMGSSK is analyzed theoretically, and validated by Monte Carlo simulation. It is shown that the proposed AMGSSK scheme has good performance in SER and spectral efficiency.

Flood Maps and Bank Shifting of Dharla River in Bangladesh

Bangladesh is prone to severe flooding as being located at the confluence of three mighty rivers named the Ganges, Brahmaputra, and Meghna. As a consequence, river flooding and erosion are common natural disasters that severely affect the landscape, lives and economy of the country. Dharla River, one of the trans-boundary rivers originated in the Himalayas, along with Brahmaputra River has a great influence on the recurring floods and erosion in north-western Bangladesh. Almost in every year, excessive erosion and embankment damages caused by Dharla render a thousand of people homeless with massive loss of crops and poultries. As per the environmentalists, this is a matter of huge concern as development of accurate flood maps and erosion prediction for Dharla River has been very challenging. In this study, the flood map and Dharla River bank shifting study have been developed by using HEC-RAS 4.1.0 hydrodynamic model and Landsat satellite images. In addition, the HEC-GeoRAS was used to establish the river reach for HEC-RAS. The calibration and validation have been performed using the observed and simulated water levels for the years of 2013 and 2014 respectively. The HEC-RAS flood water level output was used in HEC-GeoRAS for raster interpolation followed by overlain onto the land surface elevation of the study area. Then, the difference between water level interpolation and land elevation surfaces has been considered as a depth of inundation which is performed in Arc-Map 10.2. Flood maps have been generated for the years 2010, 2013, and 2014 for highest water level of each year. The erosion prone areas have been indicated by analyzing bank shifting of Dharla River for the years 1987, 1997, 2007, and 2017 by digitizing the satellite images in Arc-GIS 10.2. From the observation it has been found that the course of the Dharla River has been shifted vastly since 1987 to 2017 due to erosion.

基于SVM与Mean-Shift的非刚性目标跟踪框架

针对动态背景下,序列图像中的非刚性目标跟踪问题,提出了一种基于支持向量机(support vector machine,SVM)和均值移动(Mean-Shift)的序列图像目标跟踪框架。在初始图像中选择跟踪目标所处的矩形框,将目标框周围一定范围的像素作为背景。以目标和背景数据训练SVM二值分类器。运用得到的分类器对下一帧图像相同区域内的像素分类,得到二值的置信图(confidence map),在置信图范围内运用Mean-Shift算法求得当前目标位置,移动目标框和背景框的中心到目标位置,以10%的比例缩放目标框并选择最优者以适应目标尺度变化。以此时的目标像素和背景像素训练新的SVM分类器,进行下一幅图像的跟踪,直至完成整个序列图像跟踪任务。实验证明,该方法适用于动态背景及非刚性目标的跟踪,且实时性较好。

MODEL SHIFT AND STRANGE ATTRACTOR ON MBIUS STRIP

A new model shift mapping was given in bilateral symbol space. It is topologically conjugate with the traditional shift mapping. Similar to Smale Horseshoe, a model was constructed correspondent to the model shift mapping, i.e., a class of mapping on Mbius strip was given. Its attractors' structure and dynamical behaviour were described.

基于虚拟坐标的矢量地图差值扩展可逆水印方法

传统差值扩展技术受数据相关性限制,直接应用于矢量数据可逆水印方案易导致较低的水印容量和较大的数据失真,对顶点相关性低的矢量地图,水印效果更差。为实现更高的水印容量并控制数据失真,该文针对传统差值扩展技术提出改进:①在顶点坐标之间插入虚拟坐标,以虚拟坐标为参考点计算坐标差值;②将计算得到的坐标差值直方图向左平移,使直方图峰值点与原点重合;③水印以差值扩展的方式嵌入平移后的坐标差值中。实验结果表明:该算法的水印容量为2 bit/点,至少是传统差值扩展水印容量的6倍;与传统差值扩展方法相比,数据失真更小,原始地图坐标与水印地图坐标的RMSE和地图坐标最大改变量Max-R均大幅降低,算法严格可逆且对顶点相关性低的矢量地图水印效果仍然很好。

考虑点扩散函数效应的光谱遥感图像超分辨率制图

由于硬件设备的限制和土地覆盖类别的多样性,采集得到的光谱遥感图像的空间分辨率有时较为粗糙,导致大量混合像元产生,严重影响了土地覆盖类型空间分布的制图精度。超分辨率制图技术可以有效地处理光谱遥感图像中的混合像元,获得准确的地物类别分布信息。在遥感大数据背景下,来自同一卫星采集同一区域的多位移图像可以作为辅助数据改进超分辨率制图结果。然而,目前多位移图像插值超分辨率制图方法很少有效地考虑点扩散函数效应影响,导致制图结果精度降低。为了解决这一问题,本文提出了一种考虑点扩散函数效应的多位移光谱遥感图像超分辨率制图方法,改善土地覆盖类别制图结果。在所提出的方法中,首先,对多位移图像进行光谱解混,以生成粗糙丰度图像。然后,在考虑点扩散函数效应的情况下,对粗糙丰度图像先采用面到点克里格法,然后进行理想方波滤波,得到改善的粗糙丰度图像。接下来,通过插值对改善的粗糙丰度图像进行上采样以获得上采样丰度图像,并对上采样的所有丰度图像进行整合以获得精细丰度图像。最后,根据精细丰度图像提供的类别比例信息,使用类别分配方法将类别标签分配给亚像元,以获得理想的制图结果。实验结果表明,通过减少点扩散函数效应影响,所提出的方法展示出最佳性能表现,例如在美国华盛顿特区数据集实验结果的总体精度分别达到77.63%和Kappa系数达到0.7263。

标准分幅土地利用现状图制作流程优化设计——基于苍穹国土调查系统平台

苍穹国土调查系统平台软件是第三次国土调查和年度变更调查工作使用的平台软件之一,很多区县的国土调查都使用苍穹国土调查系统平台软件。每年国土变更调查通过国家核查后都要制作标准土地利用现状图,制作土地利用现状图中调整地类图斑注记的遮盖占整个制作过程的工时的90%以上,本文论述通过地类图斑注记自动位置调整的方式对标准土地利用现状图制作过程进行优化,在提高了制图质量的同时,也大幅度提高了制图效率。

Generation and Analysis of Hybrid-Electric Vehicle Transmission Shift Schedules with a Torque Split Algorithm

The increased concern over global climate change and lack of long-term sustainability of fossil fuels in the projected future has prompted further research into advanced alternative fuel vehicles to reduce vehicle emissions and fuel consumption. One of the primary advanced vehicle research areas involves electrification and hybridization of vehicles. As hybrid-electric vehicle technology has advanced, so has the need for more innovative control schemes for hybrid vehicles, including the development and optimization of hybrid powertrain transmission shift schedules. The hybrid shift schedule works in tandem with a cost function-based torque split algorithm that dynamically determines the optimal torque command for the electric motor and engine. The focus of this work is to develop and analyze the benefits and limitations of two different shift schedules for a position-3 (P3) parallel hybrid-electric vehicle. a traditional two-parameter shift schedule that operates as a function of vehicle accelerator position and vehicle speed (state of charge (SOC) independent shift schedule), and a three-parameter shift schedule that also adapts to fluctuations in the state of charge of the high voltage batteries (SOC dependent shift schedule). The shift schedules were generated using an exhaustive search coupled with a fitness function to evaluate all possible vehicle operating points. The generated shift schedules were then tested in the software-in-the-loop (SIL) environment and the vehicle-in-the-loop (VIL) environment and compared to each other, as well as to the stock 8L45 8-speed transmission shift schedule. The results show that both generated shift schedules improved upon the stock transmission shift schedule used in the hybrid powertrain comparing component efficiency, vehicle efficiency, engine fuel economy, and vehicle fuel economy.

Mode shift and stability control of a current mode controlled buck-boost converter operating in discontinuous conduction mode with ramp compensation

By establishing the discrete iterative mapping model of a current mode controlled buck-boost converter, this paper studies the mechanism of mode shift and stability control of the buck-boost converter operating in discontinuous conduction mode with a ramp compensation current. With the bifurcation diagrazn, Lyapunov exponent spectrum, time- domain waveform and parameter space map, the performance of the buck-boost converter circuit utilizing a compensating ramp current has been analysed. The obtained results indicate that the system trajectory is weakly chaotic and strongly intermittent under discontinuous conduction mode. By using ramp compensation, the buck-boost converter can shift from discontinuous conduction mode to continuous conduction mode, and effectively operates in the stable period-one region.

一种改进的基于SVM与Meanshift的目标跟踪

在研究基于支持向量机(Support Vector Machine,SVM)和均值漂移(Mean shift)跟踪算法基础上,为了提高目标跟踪的精确度和效率,提出了一种改进的目标跟踪算法。首先将目标跟踪转化为目标和背景的二分类问题,提取目标和背景的特征信息,采用粗糙集理论中的属性约简算法提取它们的有效特征,将目标和背景的特征分别作为正负样本训练SVM,得到背景与目标的总体分类器。借助总体分类器来区分临近下一帧中的目标和背景,并得到置信图;最后通过Mean shift算法找到置信图的峰值,从而获得目标的新位置。实验结果表明,改进方法能有效地提高目标的跟踪精度,同时加快了跟踪速度。

基于Bloch-Siegert Shift的7.0 T磁共振电特性成像研究

磁共振电特性成像是一种不同于质子密度成像的方法,该研究基于Bloch-Siegert shift(BSS),首先重建了射频场幅度,计算得到介电常数的分布,而射频场的相位是由磁化强度的相位分量近似得到,进而计算得到电导率的分布。实验利用Bruker 7.0 T磁共振设备,对两种水模和活体Balb/c小鼠进行了成像,得到电特性图像。结果表明,Bloch-Siegert B1+映像在成像效率上显著优于双角度B1+映像。该研究可为组织电特性的B1场成像选取合适的B 1mapping技术提供参考,为推动磁共振电特性的实用化提供基础研究支持。

Conformal Analysis of Spatial Shift in High Resolution Satellite Data (HRSD)

Advent of High Resolution Satellite Data (HRSD) with development of high spatial resolution sensors have revolutionized the generation of large scale maps. Generation of large scale digital utility maps using HRSD involves different methodologies and includes several steps wherein errors or spatial shift may be induced at any stage of data generation. It may be interesting to note that the characteristics of the spatial shift vary with methodologies adopted in its processing and has unique implications with respect to the data usage along with its application. Spatial shifts of points on a satellite data is result of unexpected translation and rotation of pixel with respect to the original location. Present study analyzes the spatial shift generated in satellite data with reference to the change in area and orientation of a group of pixels i.e. conformal and equal area properties of the rectified satellite data. This study aims to establish a relationship between the spatial resolutions of the satellite image used for digital map generation with the spatial accuracy achieved. In this study, Ground Control Points (GCP’s) identified on satellite data for a sample study area were validated using Differential Global Positioning System. Five different high resolution satellite images were analyzed to verify changes in area and shape with reference to the GCP’s. The results indicate that with improvement in the spatial resolution, higher precision in the digital maps is accomplished in terms of spatial shift of the points.

自适应可调节边界的蚁狮优化算法

针对蚁狮算法存在的收敛速度较慢、寻优精度较低和无法很好地摆脱局部最优解等缺陷,提出一种自适应可调节边界的蚁狮优化算法(ABALO)。首先,利用Bernouilli shift混沌映射初始化种群,增强种群的多样性与稳定性;其次,引入比例参数改进蚁狮为捕获蚂蚁而设置的陷阱大小收缩规律,提升算法的收敛速度;再次,引入莱维飞行策略,对位置更新进行变异操作,并采用贪心思想,仅保留位置变动后适应度有改进的解,帮助算法摆脱局部最优解;最后,利用动态系数改变位置更新的权重,促使算法前期着重探索局部最优解,后期重点挖掘全局最优解,进而提升算法的寻优精度。经9个基准测试函数仿真测试验证,提出的ABALO算法在收敛速度和寻优精度均有较明显的提升,寻优性能良好。

煤气化燃料电池联合系统中固体氧化物燃料电池堆性能

煤气化燃料电池联合系统是下一代高效、清洁发电技术的重要选择之一。为避免煤合成气在固体氧化物燃料电池堆内由于CO歧化反应形成积碳,需对合成气进行一定程度加湿。利用替代映射方法构建了固体氧化物燃料电池堆多物理场多尺度模型,分析不同加湿程度下的电堆性能。加湿后,电堆内水煤气变换反应速率显著增大,并与H_(2)和CO的电化学反应相互影响。在电堆内电池流道入口附近,水煤气变换反应尤为强烈,将CO快速转变为H_(2),补充了H_(2)电化学反应的消耗。但加湿程度的增大也会降低H_(2)能斯特电势,抑制流道入口段附近的H_(2)电化学反应速率。距流道入口大于60 mm的部分,CO和H_(2)分压接近平衡,水煤气变换反应减弱,气体反应速率受电化学反应控制。流道入口段H/O体积分数比和C/O体积分数比都较低,易发生积碳。50%以上的加湿可显著降低电堆内的积碳风险。加湿会造成电堆性能下降,采用的合成气组成条件下,100%加湿造成电堆性能损失4.65%。

注意力机制与自适应尺度融合的场景文本检测

在场景文本检测任务中,由于图像背景复杂、文本实例尺度不一等问题,导致现有模型的文本检测精度不高。为此,本文设计了一种基于注意力机制与自适应尺度融合的场景文本检测模型。首先,通过引入高效通道注意力机制,提高了特征提取网络的表征能力,降低了文字的漏检率和误报率;其次,通过设计自适应尺度融合模块,动态融合不同尺度特征,增强了模型对不同尺度文本实例的检测和定位能力。实验结果表明,本文提出的模型在Total-Text和MSRATD500共2个数据集上的F综合指标分别达到85.1%和84.1%,在同类型算法中处于领先水平。

条纹反射法中新的缺陷表征质量图

使用相移法测量物体形貌时,质量导引法在相位解包裹中起着重要作用。在检测高反光待测物表面缺陷时,相移条纹调制度常用来识别表面缺陷。本文通过将Sobel梯度与条纹调制相结合,提出了新的缺陷表征质量图,即调制度-Sobel梯度偏差质量图(modulation-sobel gradient variance,MSGV)。将解包裹相位图和原始相位图的均方根误差、峰值信噪比、信噪比3个性能作数据对比,对相位解包裹数据进行模拟测试。结果显示,MSGV的平均峰值信噪比较调制度-相位梯度偏差质量图(modulation-phase gradient variance,MPGV)提升了约1.97%,均方根误差减小了约2.91%。表明本文提出的MSGV算法相对于传统算法有一定优越性,具有更高的抗噪性和更低的解包裹误差。将所提出的方法对鼓型滚子曲面进行缺陷检测与定位,结果表明,MSGV能更好地显示出缺陷的轮廓信息。

多模块高温气冷堆人机界面分析研究

多模块高温气冷堆核电站的班组模式采用一名操纵员同时监控两个核蒸汽供应系统(NSSS)模块,因此主控室人机界面合理设计对核电站的运行安全至关重要。为了探索操纵员在额定功率运行条件下经常关注的参数以及人机界面中大屏幕设计的合理性,提出了一种基于眼动仪测量的人机交互评价方法。在模拟机试验过程中,使用眼动仪获取操纵员监视两个NSSS模块时的眼动数据,并对该眼动数据进行分析,得到操纵员对人机界面中不同运行系统和参数的关注度。试验结果表明:操纵员对于不同的运行参数关注度并不一样,通过所提方法可以得到额定功率运行条件下操纵员关注度最高的参数。该方法可以用于优化人机界面,同时可以判断大屏幕设计的合理性。

特征保持点云数据精简

由于三维扫描设备采集的点云数据庞大,本文提出了一种特征保持的点云精简方法以在减少冗余数据的同时更好地保持原始曲面的几何特征。首先,利用K均值聚类法在空间域对点云全局聚类,对点云构建K-d树并以K-d树的部分节点作为初始化聚类中心。然后,用主成分分析法估计点云法矢和候选特征点,遍历每个聚类,若类中包含特征点则将该类细分为多个子类,细分时将聚类映射到高斯球。最后,基于自适应均值漂移法对高斯球上的数据进行分类,高斯球上的聚类结果对应为空间聚类细分结果,各聚类中心的集合为精简结果。以多个实物模型为例验证了算法的有效性。结果表明,本文方法精简的点云在平坦区域保留少数点,在高曲率区域保留更多的点。相比于非均匀网格、层次聚类、K均值点云精简法,该方法对包含尖锐特征的曲面精简误差最小,更好地保留了原始曲面的几何特征。

逆极限空间的转移映射

证明了关于X的逆极限空间的转移映射具有下列结论 :(1)若 f是连续满射 ,则f具有Korner性质的充要条件是转移映射具有Korner性质 ;(2 ) f在其测度中心上是Li_Yorke混沌的当且仅当转移映射在其测度中心上是Li_Yorke混沌的 ,对Devaney混沌也如此 .