Multiple radar systems represent an attractive option for target tracking because they can significantly enlarge the area coverage and improve both the probability of trajectory detection and the localization accuracy. The presence of multiple extended targets or weak targets is a challenge for multiple radar systems. Moreover, their performance may be severely deteriorated by regions characterized by a high clutter density. In this article, an algorithm for detection and tracking of multiple targets, extended or weak, based on measurements provided by multiple radars in an environment with heavily cluttered regions, is proposed. The proposed method features three stages. In the first stage, past measurements are exploited to build a spatiotemporal clutter map in each radar; a weight is then assigned to each measurement to assess its significance. In the second stage, a track-before-detect algorithm, based on a weighted 3-D Hough transform, is applied to obtain target tracklets. In the third stage, a low-complexity tracklet association method, exploiting a lion reproduction model, is applied to associate tracklets of the same target. Three experiments are presented to illustrate the effectiveness of the proposed approach. The first experiment is based on synthetic data, the second one is based on actual data from a radar network with two homogeneous air surveillance radars, and the third one is based on actual data from a radar network with four different marine surveillance radars. The results reveal that the proposed method can outperform competing approaches.

Aiming at the problem of electromagnetic compatibility caused by the high-voltage electric drive system (HEDS) in electric vehicles, a model of the HEDS based on the vehicle is established to predict conducted electromagnetic interference (EMI) of the HEDS. First, the electromagnetic environment inside electric vehicles is analyzed theoretically. Then, the various parts of the HEDS are accurately modeled, which include the power buses, inverter, and motor. Based on the theory of multiconductor transmission line, a generic model of power buses suitable for two screening designs is presented. In order to accurately simulate the operating characteristics of the inverter, the drive circuit and the parasitic parameters of the dc-link capacitor block and the insulated gate bipolar transistor module are considered. The motor model takes into account the low-impedance antiresonance phenomenon in the measured motor impedance. Finally, the HEDS is simulated with PSPICE 16.6, and the simulation results agree well with the experimental measurements. The proposed model can accurately predict the system-level conducted EMI of the vehicle-mounted HEDS up to 100 MHz, with an error of 4 dB or less at almost all frequencies below 56 MHz and less than 7 dB at most frequencies in the 56–100 MHz.

To address the problems of the existing motor behavioral models, which are not suitable for time-domain simulation, difficult to parameterize, cannot capture multiple resonances, and neglect the low-impedance antiresonance phenomenon, a motor behavioral modeling approach based on series and parallel resonances in common-mode and differential-mode impedance is first proposed. Compared with the measured results and existing models, the presented motor model indicates significant improvements in terms of accuracy, universality, and convenience. Secondly, a high-frequency model of the high-voltage electric drive system (EDS) is developed based on the cable model, the inverter model, and the novel motor behavioral model, which considers various parasitics at high frequencies. Comparison with experimental results depicts that the novel EDS model can effectively predict system-level conducted electromagnetic interference up to 100 MHz with an error of 5 dB or less at most frequencies. Finally, compared with the existing frequency modeling technique, it further demonstrates that the proposed EDS modeling method displays significant superiority in respect of improving prediction precision and applicable frequency range.

Software bug localization aiming to determine the locations needed to be fixed for a bug report is one of the most tedious and effort consuming activities in software debugging. Learning-to-rank (LR) is the state-of-the-art approach proposed by Ye et al. to recommending relevant files for bug localization. Ye et al.'s experimental results show that the LR approach significantly outperforms previous bug localization approaches in terms of "precision" and "accuracy". However, this evaluation does not take into account the influence of the size of the recommended files on the efficiency in detecting bugs. In practice, developers will generally spend more code inspection effort to detect bugs if larger files are recommended. In this paper, we use six large-scale open-source Java projects to evaluate the LR approach in the context of effort-aware bug localization. Our results, surprisingly, show that, when taking into account the code inspection effort to detect bugs, the LR approach is similar to or even worse than the standard VSM (Vector Space Model), a naïve IR-based bug localization approach.

Previous studies have shown that process metrics are useful for building fault-proneness prediction models. In particular, it has been found that those process metrics incorporating developer experience (defined as the percentage of the code a developer contributes) exhibit a good ability to predict fault-proneness. However, developer quality, which we strongly believe should have a great influence on software quality, is surprisingly ignored. In this paper, we first quantify the quality of a developer via the percentage of history bug-introduce commits over all his/her commits during the development process. Then, we leverage developer quality information to develop eight file quality metrics. Finally, we empirically study the usefulness of these eight file quality metrics for fault-proneness prediction. Based on eight open source software systems, our experiment results show that: 1) these proposed file quality metrics capture additional information compared with existing process metrics, 2) almost all the proposed file quality metrics have a significant association with fault-proneness in an expected direction, and 3) the proposed file quality metrics can in general improve the effectiveness of fault-proneness prediction models when together used with existing process metrics. These results suggest that developer quality has a strong influence on software quality and should be taken into account when predicting software fault-proneness.

An oscillator is a key component of a satellite communication measurement and control system, performing symmetry precisely as a time frequency reference. At the same time, the phase noise index has a close coupling relationship with the overall performance of the entire system, while persistently breaking the symmetry property of the oscillator during work. It is very important to study and reasonably allocate the phase noise index. According to the theoretical formula of phase noise, this paper analyzes the power law spectral model in the frequency domain and the noise jitter characteristics in the time domain. Using the carrier tracking loop in the measurement system, the frequency domain transfer model of phase noise is established, and typical analysis results are given. A discrete fractional integration algorithm is proposed, which can generate the phase noise time domain sequence under the given power law spectral model coefficients. The proposed algorithm is more realistic compared with the previous numerical calculation method, and has sufficient accuracy compared with the results of the instrument. After frequency domain conversion, the RMS deviation between the simulated noise sequence in the frequency domain and the measured single sideband power spectral density is less than 2.5 dB, indicating that the phase noise sequence can reflect the frequency domain characteristics more completely. A communication measurement simulation system is built, and a discrete sequence simulation analysis method combining frequency domain and time domain is provided, and the coupling relationship of key indicators such as phase noise, thermal noise, communication data rate, modulation method and bit error rate is synthesized. The results show that the BER of the QPSK/BPSK communication system will not be significantly reduced if the phase jitter RMS caused by the phase noise is less than 5 degrees, so 5 degrees can be used as a reference for the decomposition of the carrier SSB phase noise index. The simulation results have been successfully applied to a satellite inter-satellite link system, which has universal practical application value.