Resolution-independent Up-sampling for Depth Map Using Fractal Transforms

( Meiqin Liu ),( Yao Zhao ),( Chunyu Lin ),( Huihui Bai ),( Chao Yao ) 한국인터넷정보학회 2016 KSII Transactions on Internet and Information Syst Vol.10 No.6

Due to the limitation of the bandwidth resource and capture resolution of depth cameras, low resolution depth maps should be up-sampled to high resolution so that they can correspond to their texture images. In this paper, a novel depth map up-sampling algorithm is proposed by exploiting the fractal internal self-referential feature. Fractal parameters which are extracted from a depth map, describe the internal self-referential feature of the depth map, do not introduce inherent scale and just retain the relational information of the depth map, i.e., fractal transforms provide a resolution-independent description for depth maps and could up-sample depth maps to an arbitrary high resolution. Then, an enhancement method is also proposed to further improve the performance of the up-sampled depth map. The experimental results demonstrate that better quality of synthesized views is achieved both on objective and subjective performance. Most important of all, arbitrary resolution depth maps can be obtained with the aid of the proposed scheme.

Gasification reactivity and combustion characteristics of semi‑coke

Meiqin Zha,Wei Xia,Qiang Niu 한국탄소학회 2019 Carbon Letters Vol.29 No.6

Various semi-cokes were obtained from medium–low-temperature pyrolysis of Shenmu long flame coal. The combustion characteristic index and CO2 gasification reactivity of semi-cokes were measured and analyzed using thermogravimetry analysis. The influence of particle size on CO2 gasification reactivities of these semi-cokes was studied. In addition, the Brunauer–Emmett–Teller surface area (SBET), carbon material structure order and carbon crystalline structure were examined by N2 adsorption, Raman spectroscopy and powder X-ray diffraction. All of these properties were used to evaluate the CO2 gasification reactivity of these semi-cokes. The results show that the gasification reactivity of semi-cokes decreases with an increasing crystallinity and structure order. Surface area of the pores is proportional to the reactivity of the semi-coke; the greater the surface area, the faster the gasification reaction rate.

A Single-Stage High Gain Current Source Inverter for Grid-Connected Photovoltaic System

Meiqin Mao,Yajun Zheng,Liuchen Chang,Haibo Xu 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6

The output voltage range of PV cells is widely influenced by the environment factors, such as temperature, solar radiation, etc. The lower output voltage of solar array can hardly meet the requirements for grid-connected operation of the system. To achieve high voltage gain and a steady ac output voltage in spite of the low dc input voltage, this paper presents a novel single-stage high gain current source inverter (CSI). The topology of the proposed inverter is derived from conventional tri-state current source inverter by introducing an impedance network with two symmetrical inductors and diodes separately. Theoretical analysis of operation modes and high voltage gain performance for the proposed inverter is presented, followed by the simulation of the proposed inverter in grid-connected photovoltaic (PV) system carried out on MATLAB.

Economic Analysis of the Microgrid with Multi-energy and Electric Vehicles

Mao Meiqin,Sun Shujuan,Liuchen Chang 전력전자학회 2011 ICPE(ISPE)논문집 Vol.2011 No.5

Electric vehicles (EVs) may play dual roles when they plug in a microgrid. They appear as loads during charging, meanwhile they may also be used as storage units to supply energy to the rest loads in the microgrid if the batteries have the sufficient spare energy. Considering the characteristic of bidirectional energy flow of EVs in a microgrid, this paper proposes the energy dispatch model and strategies for the microgrid including Wind generators, Photovoltaic systems, Battery storages, EVs and other local loads to analyze the impact of incorporating vehicles within and without microgrid on the economic operation of the microgrid. The simulation results indicate that incorporating EVs within the microgrid can not only minimize the capital cost of storages and reduce operation cost of the microgrid’s operator, but also save the cost of EVs’s owners.

Gasification reactivity and combustion characteristics of semi-coke

Zha Meiqin,Xia Wei,Niu Qiang 한국탄소학회 2019 Carbon Letters Vol.29 No.6

Various semi-cokes were obtained from medium–low-temperature pyrolysis of Shenmu long flame coal. The combustion characteristic index and CO2 gasification reactivity of semi-cokes were measured and analyzed using thermogravimetry analysis. The influence of particle size on CO2 gasification reactivities of these semi-cokes was studied. In addition, the Brunauer–Emmett–Teller surface area (SBET), carbon material structure order and carbon crystalline structure were examined by N2 adsorption, Raman spectroscopy and powder X-ray diffraction. All of these properties were used to evaluate the CO2 gasification reactivity of these semi-cokes. The results show that the gasification reactivity of semi-cokes decreases with an increasing crystallinity and structure order. Surface area of the pores is proportional to the reactivity of the semi-coke; the greater the surface area, the faster the gasification reaction rate.

Sensorless Control of PMSG for A Wind Power System Based on CSC

MAO Meiqin,LIU Fuyan,MU Junsheng,XU Bin 전력전자학회 2011 ICPE(ISPE)논문집 Vol.2011 No.5

This paper presents sensorless rotor-flux-oriented control algorithms for the PMSG used in the direct drive wind generation system with a back-to-back current source converter. The proposed algorithms are based on phase-lock-loop and model reference adaptive system methods. These algorithms are analyzed, compared and verified by the simulation and experiment. The simulation and experiment results show that the PLL method is simpler, but more accurate, and has a faster dynamic performance than MRAS method.

Multi-Agent Based Simulation for Microgrid Energy Management

Mao Meiqin,Dong Wei,Liuchen Chang 전력전자학회 2011 ICPE(ISPE)논문집 Vol.2011 No.5

This paper presents a general multi-agent based model for the hierarchical and distributed energy control of a Microgrid. In this model, the agents under three different levels are classified and defined in detail. And based on the model, a novel simulation platform for the energy management system of the Microgrid (EMS-MG) is designed in terms of Client-Server and implemented under C++ Builder environment. Taking the generation automatic control for example and by the proposed model and implemented EMS-MG, a simulation result is shown to illustrate the operation process of the simulation platform and present the benefits of the proposed method.

Single Phase Converter with Power Decoupling and Reactive Power Control for Bi-directional EV Charger

Peiji Zhu,Meiqin Mao,Shuang Xu 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5

In traditional single phase converters for EV chargers used in private cars, the power flow is only unidirectional, and the bulky and short-lifetime electrolytic capacitors are usually used to issue the second-order ripple power between the AC and DC side. To address the problem, this paper proposes a control strategy to enable the single phase EV charger to achieve both four-quadrant operation and power decoupling control at the same time so that the EVs can respond dispatching commands from the future smart grid as distributed energy resources, meanwhile the size of the charger can be reduced. This control method is based on our previous work, proposed novel topology of single phase converter using a small film capacitor to decouple the second-order power. The operation principle of the proposed control strategy is analyzed in detail, and the design method of decoupling capacitance for both power decoupling and reactive power control purposes is provided. Simulation results by MATLAB/Simulink are provided to verify the effectiveness of the proposed control strategy.

Improved SVM for High Gain Tri-state CSI to Reduce DC Side Inductor Current Ripple

Chufeng Li,Liuchen Chang,Meiqin Mao 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5

Extending our previous work proposing a high gain tri-state current source inverter (CSI), in this paper, an improved space vector modulation (SVM) method is proposed in order to reduce the DC side inductor current ripple. By the proposed SVM method, the active state time is divided into four equal segments and the shoot-through state time is divided into six equal segments and inserted into the four equal active state segments, respectively. Theoretically, the maximum ripple can be obtained to 1/3 of that compared with the traditional SVM mode. The proposed improved SVM method is compared with the traditional SVM method. Simulation and experimental results verify the effectiveness of the proposed strategy.

Autonomous Controller Based on Synchronous Generator dq0 Model for Micro Grid Inverters

Yan Du,Jianhui Su,Meiqin Mao,Xiangzhen Yang 전력전자학회 2011 ICPE(ISPE)논문집 Vol.2011 No.5

the parallel operation of voltage source inverter (VSI) in microgrid could benefit from characteristics of synchronous generator (SG) such as the kinetic energy stored in rotor, the self-isochronous and the droop characteristics if inverter can behave like generator in power system. Therefore an autonomous controller based on dq0 model of SG for microgrid inverter is proposed to mimic the above those characteristic of SG. Moreover, the inverter is designed to serve as either UF node or PQ node in micro grid by integrating a virtual primary frequency regulator (VPFR) and a virtual excitation regulator (VER) in the proposed controller. The results of simulation show the excellent performances of the proposed autonomous controller on voltage regulation, power sharing and seamless mode transfer.