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Railway timetable scheduling is a fundamental operational problem in the railway industry and has significant influence on the quality of service provided by the transport system. This paper explores the periodic railway timetable...
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Railway timetable scheduling is a fundamental operational problem in the railway industry and has significant influence on the quality of service provided by the transport system. This paper explores the periodic railway timetable scheduling (PRTS) problem, with the objective to minimize the average waiting time of the transfer passengers. Unlike traditional PRTS models that only involve service lines with fixed cycles, this paper presents a more flexible model by allowing the cycle of service lines and the number of transfer passengers to vary with the time period. An enhanced differential evolution (DE) algorithm with dual populations, termed “dual-population DE” (DP-DE), was developed to solve the PRTS problem, yielding high-quality solutions. In the DP-DE, two populations cooperate during the evolution; the first focuses on global search by adopting parameter settings and operators that help maintain population diversity, while the second one focuses on speeding up convergence by adopting parameter settings and operators that are good for local fine tuning. A novel bidirectional migration operator is proposed to share the search experience between the two populations. The proposed DP-DE has been applied to optimize the timetable of the Guangzhou Metro system in Mainland China and six artificial periodic railway systems. Two conventional deterministic algorithms and seven highly regarded evolutionary algorithms are used for comparison. The comparison results reveal that the performance of DP-PE is very promising.
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In this paper, we propose a real-time multicamera people localization method based on line sampling of image foregrounds. For each view, these line samples are originated from the vanishing point of lines perpendicular to the grou...
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In this paper, we propose a real-time multicamera people localization method based on line sampling of image foregrounds. For each view, these line samples are originated from the vanishing point of lines perpendicular to the ground plane. With these line samples, vertical line samples in the 3-D scene can be reconstructed for potential human locations. After some efficient geometric refinement and filtering procedures, the remaining qualified 3-D line samples are clustered and integrated for the identification of locations and heights of people in the scene. Both indoor and outdoor scenarios are examined to demonstrate the effectiveness of our approach in handling serious occlusion in crowed scenes. The average localization error of less than 15 cm for average viewing distance of 15m suggests that our method can be applied to a broad range of surveillance applications that require the real-time computation of localization without using special hardware for acceleration.
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Supervised manifold learning has been successfully applied to action recognition, in which class label information could improve the recognition performance. However, the learned manifold may not be able to well preserve both the ...
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Supervised manifold learning has been successfully applied to action recognition, in which class label information could improve the recognition performance. However, the learned manifold may not be able to well preserve both the local structure and global constraint of temporal labels in action sequences. To overcome this problem, this paper proposes a new supervised manifold learning algorithm called supervised spatio-temporal neighborhood topology learning (SSTNTL) for action recognition. By analyzing the topological characteristics in the context of action recognition, we propose to construct the neighborhood topology using both supervised spatial and temporal pose correspondence information. Employing the property in locality preserving projection (LPP), SSTNTL solves the generalized eigenvalue problem to obtain the best projections that not only separates data points from different classes, but also preserves local structures and temporal pose correspondence of sequences from the same class. Experimental results demonstrate that SSTNTL outperforms the manifold embedding methods with other topologies or local discriminant information. Moreover, compared with state-of-the-art action recognition algorithms, SSTNTL gives convincing performance for both human and gesture action recognition.
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Robot systems are developed using various hardware and software components. In conventional design methodology, each hardware component and its software are strongly coupled such that it is not easy to replace or expand them separ...
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Robot systems are developed using various hardware and software components. In conventional design methodology, each hardware component and its software are strongly coupled such that it is not easy to replace or expand them separately. For the independent development and replacement of hardware and software components, this paper proposes a novel robot development methodology based on the abstractions of software and hardware components in a multilayer architecture for cyber-physical robot systems which conjoin computational and physical resources. We introduce a context generator and a behavior translator for the abstractions in the multilayer architecture. The context generator converts sensory value data into contexts using context scripts. The behavior translator converts a behavior, selected by a software agent that is a computer program deciding an action of a robot, into a sequence of actuator commands for robots using behavior scripts. These together enable two levels of abstraction in which software and hardware components can be developed independently of each other. As a result, software agents can work flawlessly even if hardware components are replaced and vice versa. The effectiveness and applicability of the proposed methodology are demonstrated through experiments, and the related applications are provided.
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This paper presents a fast maximum power point tracking (MPPT) control algorithmfor the photovoltaic (PV) in a hybrid wind–PV system, in which the PV generatormay also need to work in a reduced power mode (RPM) to avoid dynamic o...
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This paper presents a fast maximum power point tracking (MPPT) control algorithmfor the photovoltaic (PV) in a hybrid wind–PV system, in which the PV generatormay also need to work in a reduced power mode (RPM) to avoid dynamic overloading. The two control modes, MPPT and RPM, are inherently compatible and can be readily implemented, without the need of a dumping load for the RPM. Following the establishment of a dynamic system model, the study develops the guidelines to determine the variables of a direct hill-climbing method for MPPT: the perturbation time intervals and the magnitudes of the applied perturbations. These results are then used to optimally set up a variable-step size incremental conductance (VSIC) algorithm along with adaptive RPM control. The power tracking performance and power limiting capability are verified by simulation and experiment.
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This paper presents the implementation and assessment of a direction finding proximity fuze sensor for anti-aircrafts or anti-air missiles. A higher rejection of clutter signals is achieved by employing a binary phase shift keying...
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This paper presents the implementation and assessment of a direction finding proximity fuze sensor for anti-aircrafts or anti-air missiles. A higher rejection of clutter signals is achieved by employing a binary phase shift keying modulation using Legendre sequence. The direction finding is implemented by comparing received powers from six receiving antennas equally spaced by an angle of 60$^{circ}$ around a cylindrical surface.
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In this paper, a soft-switching single-inductor push–pull converter is proposed. A push–pull converter is suitable for low-voltage photovoltaic ac module systems, because the step-up ratio of the high-frequency transformer is hi...
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In this paper, a soft-switching single-inductor push–pull converter is proposed. A push–pull converter is suitable for low-voltage photovoltaic ac module systems, because the step-up ratio of the high-frequency transformer is high, and the number of primary-side switches is relatively small. However, the conventional push–pull converter does not have high efficiency because of high-switching losses due to hard switching and transformer losses (copper and iron losses) as a result of the high turn ratio of the transformer. In the proposed converter, primary-side switches are turned ON at the zero-voltage switching condition and turned OFF at the zero-current switching condition through parallel resonance between the secondary leakage inductance of the transformer and a resonant capacitor. The proposed push–pull converter decreases the switching loss using soft switching of the primary switches. In addition, the turn ratio of the transformer can be reduced by half using a voltage-doubler of secondary side. The theoretical analysis of the proposed converter is verified by simulation and experimental results.
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An ultra-low-power super regeneration oscillator (SRO) transceiver with a 177-$mu$W ultra-low-power phase-locked loop (PLL) and automatic quench waveform generator (QWG) is presented. In order to decrease the PLL power consumption...
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An ultra-low-power super regeneration oscillator (SRO) transceiver with a 177-$mu$W ultra-low-power phase-locked loop (PLL) and automatic quench waveform generator (QWG) is presented. In order to decrease the PLL power consumption, the leakage current is measured at the VCO control voltage node, and the control voltage is compensated by the digital part. As a result, the frequency can be maintained near 2.37 GHz after the PLL is turned off. An automatic QWG circuit that can search for the critical current of the SRO automatically is proposed in order to mitigate the process, voltage, temperature variations of the conventional QWG. This chip is implemented using 90-nm CMOS technology. The die area of the full transceiver is 3 mm$,times,$4 mm and that of the PLL is 0.4 mm$,times,$0.9 mm. The leakage compensation and high-Q voltage-controlled oscillator (VCO) approach results in a frequency offset of 70 kHz and fluctuation of ${pm} $75 kHz (the maximum frequency error is 145 kHz at 60 ppm). The phase noise of the VCO output at 2.37 GHz is ${-}$103.5 dBc/Hz at 1-MHz offset. The average power consumption of the PLL is 177 $mu$W from a 1.2-V supply voltage.
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In this paper, miniature branch-line coupler and Butler matrix designs for 2.5-GHz applications are proposed using the glass-based thin-film integrated passive device (TF-IPD) technology. The size reduction is achieved by replacin...
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In this paper, miniature branch-line coupler and Butler matrix designs for 2.5-GHz applications are proposed using the glass-based thin-film integrated passive device (TF-IPD) technology. The size reduction is achieved by replacing the quarter-wavelength transmission lines in a conventional branch-line coupler with the bridged-T coil. In this way, the circuit size can be largely reduced without sacrificing the operation bandwidth. The proposed miniature branch-line coupler is then applied to the design of a 4$,times,$4 Butler matrix centered at 2.5 GHz using the glass-based TF-IPD technology. The measured results show a bandwidth of 2.4–2.6 GHz for better than 13-dB return loss with a maximal dissipation of 4 dB, amplitude imbalance within 1.1 dB, and phase imbalance less than 13$^{circ}$. Notably, the proposed Butler matrix occupies a chip area of 3.13 mm$,times,$3.3 mm, which is only about 0.026 $lambda_{ 0} times 0.027 lambda_{ 0}$ at 2.5 GHz.
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This paper presents an algorithm for implementing the nonlinear-carrier (NLC) control method for a single-phase power factor correction (PFC) rectifier without an input voltage-sensing circuit, an error amplifier in the current sh...
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This paper presents an algorithm for implementing the nonlinear-carrier (NLC) control method for a single-phase power factor correction (PFC) rectifier without an input voltage-sensing circuit, an error amplifier in the current shaping loop, or other external control components. Unity power factor and low harmonic distortion are achieved by adapting NLC control with a variable slope ramp. This ramp is created through a slope comparison without any dividers. The proposed method not only achieves a high power factor, but also efficiently simplifies complexity of integrated circuit realization. A 400-W PFC boost rectifier is implemented to verify the performance of the proposed NLC control. The highest power factor reaches to 99.9% with input voltage of 120 V/60 Hz, and the lowest input current harmonic distortion is 4.267%.
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