A lightweight and flexible CNT/Fe3O4 composite with high electromagnetic interference shielding performance

Zhuo Chao,Yingying Yu,Fang Lei,Dongmei Hu 한국탄소학회 2021 Carbon Letters Vol.31 No.1

Lightweight and flexible electromagnetic interference (EMI) shielding materials are in great demand for wearable EMI device. In the present work, lightweight and flexible carbon nanotube (CNT)/ferroferric oxide ( Fe3O4) composite film was made through a feasible chemical vapor deposition process for CNT film synthesis, followed by a hydrothermal reduction process for Fe3O4 coating. In the as-prepared composite, CNT film and Fe3O4 particles work as conductive skeleton and strong magnetic particle, respectively. The as-prepared composite film shows a novel EMI shielding effectiveness (SE) of 91 dB in the X-band, a small thickness of 0.09 mm and a low density of 0.86 g/cm3, which is superior to most of the carbonbased EMI materials.

Water temperature and salinity tolerance of embryos and spat of the mussel, Musculista senhousia

Zhuo Liang Liang,김영훈,임상민,강경호,Zhi-Fang Zhang 한국패류학회 2009 The Korean Journal of Malacology Vol.25 No.3

The effects of water temperature and salinity on embryonic development and spat survival of mussel Musculista senhousia were investigated. Embryos were incubated in water ranging from 0 to 35℃ and with salinity from 5‰ to 40‰. Mussel spat were tested in water from 0 to 40℃ and with salinity from 0‰ to 100‰. The optimal conditions for mussel embryos were 20-25℃ and salinity from 25‰ to 35‰, based on Within this temperature range, higher temperatures correponded to a shorter duration of the embryonic period. Optimisation of mussel spat survival was at 25-35℃ and salinity from 30‰ to 40‰; both values are higher than those for embryo, which hinted M. senhousia embryos are more vulnerable than spat. Temperatures below 15℃ were lethal for embryos, making temperature a feasible method with which to control the large population of M. senhousia in ark-shell farm during its spawning period.

Analysis of Cracking Development and Mechanical Characteristics of High-Filled Cut-and-Cover Tunnel

Bin Zhuo,Feiyang Wang,Yong Fang,Yan Chen,Guixia Ning 대한토목학회 2020 KSCE JOURNAL OF CIVIL ENGINEERING Vol.24 No.8

The cut-and-cover tunnel (CCT) construction scheme has led to the popularity of high-filled cut-and-cover tunnel (HFCCT). HFCCT possesses a backfilling height of 30 − 50 m. However, such a high soil column produces a large force on the structure and the structure is prone to crack, causing structural damage and difficulty in normal use. In order to provide a reference for the structural safety assessment of HFCCT, we conducted a similarity model test to study the variation law of the development of crack, displacement, and internal force of HFCCT with a coefficient of λ (the ratio of the backfilling height to the height of the cut-and-cover tunnel). In the test, a 1:20 similar scale CCT model with slope angle 70° and groove width ratio 1 was built using data from the HFCCT on the Lanyu Line. The backfilling process on site was simulated in a simulation box (360 cm long, 120 cm wide and 209 cm high). A numerical model was also built using PFC2D to verify the accuracy of the model test and further explain the crack formation mechanism of the HFCCT from a microscopic perspective. The results show that with the increase of the coefficient of λ, the bearing stage of the CCT can be roughly divided into three stages: steady growth stage, rapid growth stage, and accelerated growth stage. Furthermore, the development of cracks is closely related to the displacement and internal force of the CCT. The larger the displacement of the CCT, the greater the instability of the structure and the larger the ratio of the bending moment to the internal force, which causes the crack to develop faster.

Water temperature and salinity tolerance of embryos and spat of the mussel, Musculista senhousia

Liang, Zhuo Liang,Kim, Young-Hun,Zhang, Zhi Fang,Lim, Sang-Min,Kang, Kyoung-Ho The Malacological Society of Korea 2009 The Korean Journal of Malacology Vol.25 No.3

The effects of water temperature and salinity on embryonic development and spat survival of mussel Musculista senhousia were investigated. Embryos were incubated in water ranging from 0 to $35^{\circ}C$ and with salinity from 5‰ to 40‰. Mussel spat were tested in water from 0 to $40^{\circ}C$ and with salinity from 0‰ to 100‰. The optimal conditions for mussel embryos were $20-25^{\circ}C$ and salinity from 25‰ to 35‰, based on Within this temperature range, higher temperatures correponded to a shorter duration of the embryonic period. Optimisation of mussel spat survival was at $25-35^{\circ}C$ and salinity from 30‰ to 40‰; both values are higher than those for embryo, which hinted M. senhousia embryos are more vulnerable than spat. Temperatures below $15^{\circ}C$ were lethal for embryos, making temperature a feasible method with which to control the large population of M. senhousia in ark-shell farm during its spawning period.

Comparison Analysis of Resonant Controllers for Current Regulation of Selective Active Power Filter with Mixed Current Reference

Yi, Hao,Zhuo, Fang,Li, Yu,Zhang, Yanjun,Zhan, Wenda The Korean Institute of Power Electronics 2013 JOURNAL OF POWER ELECTRONICS Vol.13 No.5

Instead of extracting every selected harmonic component, the current reference of selective active power filter (APF) can be also obtained by filtering out the fundamental component from distorted load current for computation efficiency. This type of mixed current reference contains kinds of harmonic components and easily involves noises. In this condition, selective harmonic compensation must be realized by the current controller. With regard that selectivity is the most significant feature of controller, this paper presents specific comparison analysis between two types of resonant controllers: proportional-resonant (PR) controller and vector-resonant (VR) controller. The comparison analysis covers the relations, performances, and stability of both controllers. Analysis results conclude that the poorer selectivity of the PR controller could be relatively improved, but limitations from system stability make the improvement hardly realized. By contrast, the VR controller exhibits excellent selectivity and is more suitable for selective APF with mixed current reference. Experimental results from laboratory prototype validate the reasonability of analysis. And the features of each resonant controller are concluded.

A Novel Control Method of PAPF for Resonance Damping and Harmonics Compensation in Power System

WU Longhui,ZHUO Fang,LI Hui,LIU Jinjun,WANG Zhaoan 전력전자학회 2007 ICPE(ISPE)논문집 Vol.- No.-

In power system, capacitors are widely used to compensate reactive power, which generally cause resonance problems in harmonic distorted network. In this paper, parallel active power filter (PAPF) is used to damp the resonances. Firstly, the damping characteristics of PAPF with traditional load current detection methods (detecting current including or not including the capacitor current) are analyzed respectively. The analysis results show that PAPF with traditional load current detection methods is effective for parallel resonance damping, but can not damp series resonance when capacitor current is not included in the detecting current. And when capacitor current is included in the detecting current, PAPF is prone to be unstable and can not damp parallel and series resonance. Then a novel control method of PAPF is proposed. PAPF with the proposed control method has excellent performance in damping of both parallel resonance and series resonance, whether the capacitor current is included in the detecting current of PAPF or not. Also the PAPF with proposed method has strong ability in harmonic compensation. Finally, the experiment results are presented to verify the analysis.

Non-Isolated High Gain Bidirectional Modular DC-DC Converter with Unipolar and Bipolar Structure for DC Networks Interconnections

Lejia Sun,Fang Zhuo,Feng Wang,Hao Yi 전력전자학회 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.5

In this paper, a novel high gain bidirectional modular dc-dc converter (BMC) with unipolar and bipolar structures for dc network interconnections is proposed. When compared with traditional dc grid-connecting converters, the proposed converter can achieve a high voltage gain with a simple modular transformerless structure. A sub-modular structure for the BMC is proposed to eliminate the unbalanced current stress between the different power units (levels) in the BMC. This can realize current sharing and standardized production and assembling. In addition, phase-interval operation is introduced to the sub-modules to realize low voltage and current ripple in both sides of the converter. Furthermore, two types of bipolar topologies of the sub-modular BMC were proposed to extend its application in bipolar dc network connections. In addition, the control system was optimized for grid-connection applications by providing various control strategies. Finally, simulations of a 3-level unipolar sub-modular BMC and a 4-level bipolar sub-modular BMC were conducted, and a 1-kW experimental 3-level unipolar prototype was developed to verify the effectiveness of the proposed converter.

Non-Isolated High Gain Bidirectional Modular DC-DC Converter with Unipolar and Bipolar Structure for DC Networks Interconnections

Sun, Lejia,Zhuo, Fang,Wang, Feng,Yi, Hao The Korean Institute of Power Electronics 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.5

In this paper, a novel high gain bidirectional modular dc-dc converter (BMC) with unipolar and bipolar structures for dc network interconnections is proposed. When compared with traditional dc grid-connecting converters, the proposed converter can achieve a high voltage gain with a simple modular transformerless structure. A sub-modular structure for the BMC is proposed to eliminate the unbalanced current stress between the different power units (levels) in the BMC. This can realize current sharing and standardized production and assembling. In addition, phase-interval operation is introduced to the sub-modules to realize low voltage and current ripple in both sides of the converter. Furthermore, two types of bipolar topologies of the sub-modular BMC were proposed to extend its application in bipolar dc network connections. In addition, the control system was optimized for grid-connection applications by providing various control strategies. Finally, simulations of a 3-level unipolar sub-modular BMC and a 4-level bipolar sub-modular BMC were conducted, and a 1-kW experimental 3-level unipolar prototype was developed to verify the effectiveness of the proposed converter.

A Unify Unbalance Compensation Strategy for Islanded Microgrid with Unbalanced Condition

Hongtao Shi,Fang Zhuo,Zhiqing Geng,Dong zhang 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6

Due to the unbalance condition, the voltage of microgrid would be deteriorated. In this paper, a unify unbalance compensation strategy is proposed to suppress the unbalanced voltage and the voltage variation for islanded microgrid with unbalanced condition. Comparing to the traditional compensation strategy, where only negative sequence components of voltage are suppressed, in the proposed scheme, the voltage and frequency variations resulted from the unbalanced condition are also eliminated. A simulation model of microgrid is developed in PSIM and the simulation and experimental results verify the effectiveness of the proposed method.

A Single-phase Harmonics Extraction Algorithm Based on the Principle of Trigonometric Orthogonal Functions

Yi, Hao,Zhuo, Fang,Wang, Feng,Li, Yu,Wang, Zhenxiong The Korean Institute of Power Electronics 2017 JOURNAL OF POWER ELECTRONICS Vol.17 No.1

For a single-phase active power filter (APF), designing a more efficient algorithm to guarantee accurate and fast harmonics extraction with a lower computing cost is still a meaningful topic. The common idea still employs a IRPT-based Park transform, which was originally designed for 3-phase applications. Therefore, an additional virtual signal generation (VSG) link is necessary when it is used in the single-phase condition. This method, with virtual signal generation and transform, is obviously not the most efficient one. Regarding this problem, this paper proposes a novel harmonics extraction algorithm to further improve efficiency. The new algorithm is based on the principle of trigonometric orthogonal functions (TOF), and its mathematical principle and physical meaning are introduced in detail. Its implementation and superiority in terms of computation efficiency are analyzed by comparing it with conventional methods. Finally, its effectiveness is well validated through detailed simulations and laboratory experiments.