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Characterizing the fluctuations properties in wind speed signals is a significant problem in the field of nonlinear dynamics and aerodynamics. In this paper, firstly, to fully capture the details of the wind field fluctuation, a 3D ultrasonic anemometer is selected to measure the wind speed data in a short-term wind field experiment. Then, we employ the multifractal detrended fluctuation analysis...
Uncovering dynamics characteristics of 3D wind field is of great importance to understand the mechanisms of gas dispersal and provides useful clues for the optimization of gas source localization algorithms. In this paper, we first use a high precision 3D ultrasonic anemometer to collect the three orthogonal wind speed components and calculate corresponding instantaneous wind speed. Then we employ...
Uncovering the correlations of different flow fields, in terms of time series network analysis, is important and relevant to both engineers and businesses. We first systematically carry out experiments and record different groups of time series signals from the wind field and the gas concentration field simultaneously. Then, we employ the visibility graph method for mapping the experimental measurements...
Understanding the temporal/spatial behavior and dynamics of wind speed is of great importance for model building, wind prediction and sensor design. In the present study, we employ a recently proposed approach of multiscale multifractal analysis (MMA) to investigate the scaling properties of a group of wind speed time series recorded at ten locations with 1m interval in line. The results of MMA show...
The magnitude and sign of a time series measured from physical process contain rich information about the dynamical mechanisms. In this paper, we study the scaling properties of the magnitude and the sign from the small-scale wind speed fluctuations using the detrended fluctuation analysis (DFA), and show the impact of sampling frequency on their scaling properties. We find long-range positive correlations...
Better understanding of boundary-layer wind field is fundamental for modeling of various wind-related phenomena, e.g., gas dispersal and energy generation. In this paper, we first record three groups of the near surface wind speed time series in different locations using a high-resolution 3D ultrasonic anemometer. Then, we map these experimental time series into complex networks and detect the corresponding...
Traditionally, most ultrasonic ranging systems are excited using pulse signals. A hardware platform of ultrasonic ranging system that is excited using a sine signal is presented. On the basis of the new hardware platform, the chaotic sine frequency modulation (CSFM) sequence is proposed to excite ultrasonic transducers. Correlation characteristics of the echo signals generated using the CSFM excitation...
High echo energy is important in sonar systems to increase measurement range. A sufficient condition is derived and obtained to achieve high echo energy for pulse position modulation excitation sequences. This paper addresses echo energy analysis under the premise that crosstalk between different sonar transducers can be avoided. Experiments validate the derived sufficient condition.
In order to mining the organizational setting and interactions among coworkers from workflow logs, we define metrics to establish the relationships among originators by analyzing the information in the workflow logs. Three methods for mining organizational structure from workflow logs are presented in this paper, default mining, mining based on the similarity of activities and mining based on the...
The grid technology enables large-scale sharing and collaboration use of networked resource. Using P2P technology, grid system can have better scalability and dynamic. OGSA (open grid service architecture) provides a framework for integrating P2P technology into grid system. However, grid resource aggregation is a key issue for P2P grid. In this paper, ant-based resource aggregation algorithm is proposed...
In this paper, node mobility is used to enhance the performance of route discovery in hybrid ad hoc networks. Some fast moving nodes (FNs) collect last encounter information while they are moving within the network. Whenever they encounter static nodes (SNs), they diffuse their last encounter information to SNs. According to the temporal-spatial correlation, both FNs and SNs can compute the distance...
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