ReMotENet: Efficient Relevant Motion Event Detection for Large-scale Home Surveillance Videos

This paper addresses the problem of detecting relevant motion caused by objects of interest (e.g., person and vehicles) in large scale home surveillance videos. The traditional method usually consists of two separate steps, i.e., detecting moving objects with background subtraction running on the camera, and filtering out nuisance motion events (e.g., trees, cloud, shadow, rain/snow, flag) with deep learning based object detection and tracking running on cloud. The method is extremely slow and therefore not cost effective, and does not fully leverage the spatial-temporal redundancies with a pre-trained off-the-shelf object detector. To dramatically speedup relevant motion event detection and improve its performance, we propose a novel network for relevant motion event detection, ReMotENet, which is a unified, end-to-end data-driven method using spatial-temporal attention-based 3D ConvNets to jointly model the appearance and motion of objects-of-interest in a video. ReMotENet parses an entire video clip in one forward pass of a neural network to achieve significant speedup. Meanwhile, it exploits the properties of home surveillance videos, e.g., relevant motion is sparse both spatially and temporally, and enhances 3D ConvNets with a spatial-temporal attention model and reference-frame subtraction to encourage the network to focus on the relevant moving objects. Experiments demonstrate that our method can achieve comparable or event better performance than the object detection based method but with three to four orders of magnitude speedup (up to 20k times) on GPU devices. Our network is efficient, compact and light-weight. It can detect relevant motion on a 15s surveillance video clip within 4-8 milliseconds on a GPU and a fraction of second (0.17-0.39) on a CPU with a model size of less than 1MB.Comment: WACV1

A graph theory based energy routing algorithm in Energy Local Area Network (e-LAN)

The energy internet concept has been considered as a new development stage of the Smart Grid, which aims to increase the energy transmission efficiency and optimise the energy dispatching in time and space. Energy router is a core device in the energy internet and it connects all the devices together into a net structure and manages power flows among them. The research work presented in this paper described the energy router’s structure and function expectations from the network perspective, and improved the existing energy router design. Open-shortest-path first (OSPF) protocol and virtual circuit switching mode are referenced from the Internet in the energy local area network (e-LAN) design. This paper proposed a design of an energy routing algorithm based on graph theory in an e-LAN. A lowest-cost routing selection algorithm is designed according to the features of power transmission, and a source selection and routing design algorithm is proposed for very heavy load conditions. Both algorithms have been verified by case analyses

DC power line communication based on power/signal dual modulation in phase shift full bridge converters

For intelligent DC distributed power systems, data communication plays a vital role in system control and device monitoring. To achieve communication in a cost effective way, power/signal dual modulation (PSDM), a method that integrates data transmission with power conversion, can be utilized. In this paper, an improved PSDM method using phase shift full bridge (PSFB) converter is proposed. This method introduces a phase control based freedom in the conventional PSFB control loop to realize communication using the same power conversion circuit. In this way, decoupled data modulation and power conversion are realized without extra wiring and coupling units, and thus the system structure is simplified. More importantly, the signal intensity can be regulated by the proposed perturbation depth, and so this method can adapt to different operating conditions. Application of the proposed method to a DC distributed power system composed of several PSFB converters is discussed. A 2kW prototype system with an embedded 5kbps communication link has been implemented, and the effectiveness of the method is verified by experimental results

Direct sequence spread spectrum based PWM strategy for harmonic reduction and communication

Switched mode power supplies (SMPSs) are essential components in many applications, and electromagnetic interference is an important consideration in the SMPS design. Spread spectrum based PWM strategies have been used in SMPS designs to reduce the switching harmonics. This paper proposes a novel method to integrate a communication function into spread spectrum based PWM strategy without extra hardware costs. Direct sequence spread spectrum (DSSS) and phase shift keying (PSK) data modulation are employed to the PWM of the SMPS, so that it has reduced switching harmonics and the input and output power line voltage ripples contain data. A data demodulation algorithm has been developed for receivers, and code division multiple access (CDMA) concept is employed as communication method for a system with multiple SMPSs. The proposed method has been implemented in both Buck and Boost converters. The experimental results validated the proposed DSSS based PWM strategy for both harmonic reduction and communication

Embedding Power Line Communication in Photovoltaic Optimizer by Modulating Data in Power Control Loop

In Photovoltaic (PV) system, dc-dc power optimizer (DCPO) is an option to maximize output power. At the same time, data links among DCPOs are often required for system monitoring and controlling. This paper proposes a novel power line communication (PLC) method for the DCPOs, in which the data of a DCPO is modulated into the control loop of power converter, and then transmitted through the series-connected dc power line to other DCPOs. In the process of communication, differential phase shift keying (DPSK) modulation and discrete Fourier transformation (DFT) demodulation are employed. To analyze the quality of communication, the communication model of the system is built, based on small-signal model. Furthermore, the noises of the system, including switching, maximum power point tracking (MPPT) and additive white Gaussian noise (AWGN), are discussed and measured to evaluate the signal-to-noise ratio (SNR). At last, an experimental system including 6 DCPOs is established and tested, which verifies the feasibility and effectiveness of the proposed method

A DC bus signaling control strategy for DC microgrids with consideration of battery state of charge balancing

In a DC microgrid, it is essential to have a coordinated control for multiple distributed generations and energy storage systems. This paper presents a DC bus signaling control strategy for DC microgrids with consideration of the state of charge (SoC) balancing among multiple battery energy storage units to ensure reliable current sharing among various sources. In the proposed method, operation modes of the DC microgrid are based on DC bus voltage deviation, and seamless transition can be achieved. Moreover, battery SoC balancing can be achieved, and overcharging or over-discharging of batteries can be avoided. MATLAB/Simulink simulation results are presented to show the effectiveness of the proposed method.</p

A review of DC bus signalling control methods in DC microgrids

DC microgrids has been proposed to adopt more renewable energy sources in future smart electric power distribution networks. DC bus signalling is one of the secondary layer control methods that has been widely used in DC microgrids when the communication infrastructure is absent or under failure. It has advantages in regulating specific DC microgrids with countable working states, such as household applications. This method has achieved fast development over the past decades and there is still no existing literature review that classifies and compares those methods. Driven by this idea, this paper provides a review based on reported DC bus signalling methods in the IEEE Xplore library

An integrated communication method for LED intelligent dimming system with switching ripple communication

Aiming at solving the problems of complex wiring and high cost of the existing distributed light emitting diode (LED) dimming system, a new LED intelligent dimming system is proposed in this paper. Power/signal multiplexing modulation and transmission technology is applied to the LED drive circuits, and power and signal simultaneously transmission through the power bus is achieved. Quaternary differential phase shift keying (QDPSK) and orthogonal frequency division multiplexing (OFDM) are used to improve the communication efficiency. It realizes the communication between multiple LEDs for intelligent dimming control without additional hardware circuit, which greatly reduce the system volume, cost and complexity, enhancing the system reliability as well. Finally, the correctness and feasibility of the LED intelligent dimming strategy is verified by PSIM simulations