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It is well-known that the electric vehicle is the main trend for the future transportation market. Obviously, fast charging for the EV battery is the urgent and critical requirement of customers which makes the high output power chargers to be the mainstream products. Modular paralleled system is a good option to extend the charging system’s power and shorten the development cycle at the same time. The traditional current sharing method cannot optimize the system’s efficiency. In this paper, a novel maximum efficiency point tracking technique is proposed to improve the efficiency for modular paralleled power system at the light load (20%~50% load) and balance the accumulative operation energy for each module as well. Both the simulation and experiment results are given to show that the average efficiency improvement reaches 1.3%.

This paper presents a control scheme to improve interleaved critical conduction mode (CRM) Totem-pole PFC input current distortion (iTHD).The Totem-pole CRM control PFC provides zero voltage soft switching (ZVS) feature. All power switches are turned off around grid voltage crosses zero volt (0V) (GVCZ) area in the conventional Totem-pole CRM control to avoid power switches working at extremely high switching frequency. This high switching frequency working may destroy the power switches. PFC input current is zero around GVCZ area when power switches are turned off in the conventional CRM control. This turned off control scheme will result in current distortion. This paper proposes a method to keep power switches continuously working at high switching frequency mode during the entire sinusoidal period without turning off around GVCZ area. The switching frequency can be limited by the proposed method. This control scheme makes the PFC input current to be controlled within the whole sinusoidal period. Better PFC input current iTHD is gotten. 3.3kW onboard charger (OBC) with GaN devices is built to verify the control scheme. The PFC input current iTHD is mitigated from 2.78% to 1.29% with proposed control scheme.

Particle swarm optimization (PSO) has been proven to be a simple yet effective algorithm for searching the optimal solutions of objective functions. The main advantage of PSO is its simplicity, but it easily gets stuck in local optima. In order to remain the original merit and raise its performance, a novel idea is proposed in this paper, which selects the best model of PSO based on the previous performance through a scheme of PSO with a switch of multiple models. Experimental results show that the PSO through the scheme outperforms any with its individual setting alone. In the future, PSO algorithms with a switch of multiple models will be a promising research field. In addition, the idea can be easily extended to select the best from multiple optimization methods.

With the higher-order sliding mode control theory, a sliding mode tracking control method is presented for an underactuated surface vessel in presence of parameter variations and external disturbances. First the basic idea of the higher-order sliding mode control is introduced, and then the second-order sliding mode tracking control law is derived based on Lyapunov second method. Theoretical analysis and simulation results show that the method can effectively eliminate system chattering and achieve the tracking manoeuvre precision positioning and get global stability and robustness at the same time.

Low temperature wafer bonding for InP/Si and InP/SiO 2 was studied. Scanning acoustic microscopy (SAM) has to be used for characterizing the bonding interface to determine if there are micro-voids ( 2 bonding. The micro-voids also appear in the wafer bonding with oxide.

Hand vein biometric identification technology has become a new research direction in domestic and international identification system. The set of hand vein image acquisition devices was designed and the light source parameters were optimized according to the image mean and standard deviation. Image preprocessing algorithm was used to further improve the image quality. Threshold method was used to remove the image background, and the image gray was normalized. It is show that the high-quality images can be obtained by using Optimized parameters acquisition device and image preprocessing procedure. The image acquisition system and pre-processing algorithm provide a good platform for further vein image feature extraction and matching.

This paper casts systematic insight into the electronic ballasts which are functionally made-up by three cascade stages, i.e., input, PFC and output. Simulation results utilizing the semi-theoretical model indicate that the fluorescent lamp operating at high frequencies is approximately a voltage dependent resistor. Further numeric analysis simplifies the lamp load network as a resistor-inductor series branch. The electrical characteristics of the output stage are revealed and described by a switched RL load. Employing the system equivalent circuit, we derive the model of the electronic ballast. And the state-space descriptions (line current, capacitor voltage, and load current are states variables) illustrate that the electronic ballast driving the fluorescent lamp is a switched linear system of third-order and four-mode.

Recognition of hand vein is becoming a research focus in biological recognition field, due to its particular advantage of uniqueness and livingness. The acquisition of clear vein image is an important premise for recognition. A quantitative assessment method of image quality is proposed based on two spatial indicators. It is shows that the relationship between the quantitative score of vein image and the drive current of near-infrared light source obeys the cubic polynomial relationship. When the driven current equals 0.524A, the image quality is optimal, and the corresponding score is 90.4. The quantitative self-consistent method developed in this work also can be applied to other digital image in more general applications.

The bare magnetic Mn 0.5 Zn 0.5 Fe 2 O 4 nanoparticles were prepared by the hydro-thermal method. The optimized preparation conditions were obtained by the orthogonal experiment. Crystal structure and the grain diameter of the particles were observed by X-ray Diffraction (XRD) and Transmission Electron Microscope (TEM), and the Curie temperature of the bare particles and the performance of the magnetic moment of the particles at different temperatures were characterized by the Vibrating Sample Magnetometer (VSM). The bare particles were modified by the oleic acid, and the modification effect was verified by the Infrared Test (IR). Mn 0.5 Zn 0.5 Fe 2 O 4 thermal-sensitive magnetic ferrofluid with excellent performance were prepared by dissolving the modified particles in the kerosene carrier. The saturation magnetization could reach up to 278Gs and the Curie temperature is confirmed to be 322K, which indicates that the quality of the Mn 0.5 Zn 0.5 Fe 2 O 4 thermal-sensitive ferrofluid is better than other Mn 0.5 Zn 0.5 Fe 2 O 4 thermal-sensitive ferrofluids prepared by the coprecipitation method previously reported (Saturation magnetization: 150Gs, Curie temperature: 340K[1]).

Although an autonomous mobile ad hoc network (MANET) is useful in many scenarios, work on the integration of MANET with Internet is more desirable. In order to realize such integration, Internet gateway is required. The main issue involved in this case is when and how a mobile node obtains information about available Internet gateways while making a minimal consumption of the scarce network resources. So an efficient gateway discovery for MANET becomes a key element to enable the use of hybrid ad hoc networks in future mobile and wireless networks. Note that performance of the Internet connectivity will be degraded greatly if obvious unidirectional links are ignored and gateway discovery packets are rebroadcast blindly during MANET nodes discovery available Internet gateway, in this paper, an effective hybrid gateway discovery algorithm for MANET is proposed to remove unidirectional links and enhance Internet connectivity simultaneously. The routing protocol called ad hoc on-demand distance vector (AODV) has been modified to set up multihop paths to the Internet gateways in the MANET. Simulation results with NS2 show that this approach can provide better performance to avoid unidirectional links and can achieve good connectivity while keeping overhead costs low.

This paper proposes an novel multipurpose digital watermarking algorithm in morphological wavelet transform domain for two purposes: to notify the copyright owner with a visible gray image watermark and to protect the copyright with an invisible binary image watermark. Both watermarks are embedded in different blocks with different methods. The experiment results indicate that the morphological wavelet has state-of-the-art performance to make the visible water hard to remove and the invisible watermark robust.

A multipurpose digital watermarking algorithm based on dual-tree Complex Wavelet Transform (CWT) is proposed for two purposes: to notify the copyright owner with a visible watermark, and to protect the copyright with an invisible watermark. These two watermarks are embedded in different blocks with different methods. Experimental results show that the dual-tree CWT has relatively high capacity to make the visible watermark hard to remove and the invisible watermark robust.