Research on experimental measurement of acoustic resistance and major accuracy influencing factors analysis

Wang Xiaoqing,Xiang Yang,Guo Zhiyong,Xia Xuebao,Shi Yuxiao,Xue Peng,Wu Shaowei 대한기계학회 2014 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.28 No.4

An experimental method of measuring acoustic surface radiation resistance is developed. The principle of the method is based on obtainingsource velocity and field pressure generated by the source. To measure surface radiation resistance, measuring probe was developedand measuring system was set up. Then, major factors that affect measurement accuracy is discussed and great improvements aregot. After that, experiments of measuring baffled circular piston were conducted to analyze its applicable frequency range. To verifyactual application effect, experiments of measuring the tube and cylinder heads of a diesel engine were performed. The results show thatthis measuring system can obtain resistance values in the frequency range from 460 to 1900 Hz with high precision. The measuring systemhas features of simple operation, convenient use, and high accuracy. Therefore, it can be used to determine surface resistance matrixof various structures.

Evaluation of Fungal Lactic Acid Accumulation Using Glycerol as the Sole Carbon Source

Xiaoqing Wang,Zhenhua Ruan,Webster Guan,Robert Kraemer,Yuan Zhong,Yan Liu 한국생물공학회 2015 Biotechnology and Bioprocess Engineering Vol.20 No.3

This study investigated the glycerol utilization for lactic acid accumulation by the filamentous fungus Rhizopus oryzae 9363 and compared it with the conventional carbon source glucose. No lactic acid accumulated in the glycerol media at 30oC, in contrast to the glucose media. Increasing the temperature from 30 to 37oC led to a 63% decrease in the average growth rate of R. oryzae in glycerol media and a 61% increase in the average cell mass yield, and the cultures on glycerol media at 37oC were able to generate 0.6 g/L lactic acid. While, raising temperature significantly inhibited lactic acid production on glucose media. Moreover, supplementing cultures with sodium pyruvate significantly improved the lactic acid synthesis of R. oryzae on glycerol media, with lactic acid concentrations reaching 1.33 g/L at 37oC and 0.67 g/L at 30oC, respectively. Our results indicate that glycerol utilization for lactic acid accumulation by Rhizopus sp. is limited by the availability of intracellular pyruvate, and controlling pyruvate flow is a key to enhancing the lactic acid accumulation.

Fast Real-Time Cardiac MRI: a Review of Current Techniques and Future Directions

Xiaoqing Wang,Martin Uecker,Li Feng 대한자기공명의과학회 2021 Investigative Magnetic Resonance Imaging Vol.25 No.4

Cardiac magnetic resonance imaging (MRI) serves as a clinical gold-standard noninvasive imaging technique for the assessment of global and regional cardiac function. Conventional cardiac MRI is limited by the long acquisition time, the need for ECG gating and/or long breathhold, and insufficient spatiotemporal resolution. Real-time cardiac cine MRI refers to high spatiotemporal cardiac imaging using data acquired continuously without synchronization or binning, and therefore of potential interest in overcoming the limitations of conventional cardiac MRI. Novel acquisition and reconstruction techniques must be employed to facilitate real-time cardiac MRI. The goal of this study is to discuss methods that have been developed for realtime cardiac MRI. In particular, we classified existing techniques into two categories based on the use of non-iterative and iterative reconstruction. In addition, we present several research trends in this direction, including deep learning-based image reconstruction and other advanced real-time cardiac MRI strategies that reconstruct images acquired from real-time free-breathing techniques.

An Improved One Cycle Control for Active Power Filters under Non-Ideal Voltage Conditions

Wang, Lei,Ren, Chunguang,Yang, Yu,Han, Xiaoqing,Wang, Peng The Korean Institute of Power Electronics 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.6

The one cycle control (OCC) scheme for active power filters (APFs) has shown excellent harmonic suppression and implementation simplicity. However, its real world application is limited because the non-ideal supply voltage for APFs can influence its performance so that the source currents are still distorted after compensation. This paper proposes a modified one cycle control (MOCC) scheme to improve the performance of three-phase shunt APFs under non-ideal supply voltage conditions. In this paper a detailed mathematical derivation has been presented and the key control law of the MOCC has been developed for adaption to the non-ideal supply voltages, following the control philosophy of simplicity. A relatively simple sequence filter is introduced to extract the harmonic components of supply voltages. The modified scheme can be easily implemented. The proposed control strategy has excellent performance and a 5kVA APF hardware platform has been implemented to validate the feasibility and performance of the proposed strategy.

Source Current Control Strategy of Active Power Filters for Unbalanced Load Compensation in Three-Phase Four-Wire Distribution Networks

Wang, Lei,Han, Xiaoqing,Meng, Runquan,Ren, Chunguang,Wang, Qi,Zhang, Baifu The Korean Institute of Power Electronics 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.5

This paper proposes a modified control strategy to improve the performance of three-phase four-leg shunt active power filters (APFs) for the compensation of three phase unbalanced loads. Unbalanced current cannot be obtained accurately by a harmonic detector due to the lower frequency. The proposed control strategy eliminates conventional harmonic detectors by directly regulating the source current. Therefore, the computational complexity is greatly reduced and the performance of the APF is improved. A mathematic model has been developed based on the source currents. The corresponding controllers have been designed based on the sinusoidal internal model principle. The proposed control strategy can guarantee excellent compensation performance and stable operation after an extreme disturbance such as a short circuit fault. In addition, the proposed technique can selectively compensate specific harmonics. A 50kVA prototype APF is implemented in the laboratory to validate the feasibility and performance of the proposed control strategy.

Enhanced robustness with damping interval widening strategy of LCL-type converter under weak grid condition

Wang, Qi,Qin, Wenping,Wang, Lei,Han, Xiaoqing,Wang, Peng The Korean Institute of Power Electronics 2020 JOURNAL OF POWER ELECTRONICS Vol.20 No.2

Active damping methods are widely adopted to present a damping effect on the resonance phenomenon without the power loss of LCL-type converters connected to a grid. However, extra sensors are used to implement the damping strategy. In this paper, a sensorless damping strategy where only the grid current is sampled has been proposed. Furthermore, the inner relationship between the tradition capacitor current feedback strategy and the proposed strategy has been clarified. Considering the digital delay and a weak grid, a robust method that uses unit delay feedback to mitigate the phase lag and to widen the effective damping interval has been developed. With this simple measure, stability is enhanced during the Nyquist frequency and robustness is improved when the LCL parameters vary and grid impedance exists. Finally, simulation and experimental results are presented to verify the feasibility and engineering significance of the proposed strategy.

A Multiplexing Modulation Strategy Based on Single-phase AC/DC Converter with OptimizedE-Capless Function

Xiaoqing Wang,Lei Jing,Bodong Li,Ning Chen,Maohang Qiu,Min Chen 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5

Active power decoupling (APD) techniques prove to be efficient in cutting passive component size for single-phase AC/DC converter, usually against bulky electrolytic capacitors (E-Cap) on DC side. Generally, no adding extra switches is expected to realize E-Capless function as well as original power factor correction (PFC). This paper proposes a multiplexing modulation strategy with optimized power-decoupling reference algorithm, employing a small LC branch as power decoupling circuit to replace large electrolytic capacitors, which could further reduce dclink capacitance. Both simulation and experimental results for a 1kW prototype are presented in this paper to validate the performance of proposed method.

Source Current Control Strategy of Active Power Filters for Unbalanced Load Compensation in Three-Phase Four-Wire Distribution Networks

Lei Wang,Xiaoqing Han,Runquan Meng,Chunguang Ren,Qi Wang,Baifu Zhang 전력전자학회 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.5

This paper proposes a modified control strategy to improve the performance of three-phase four-leg shunt active power filters (APFs) for the compensation of three phase unbalanced loads. Unbalanced current cannot be obtained accurately by a harmonic detector due to the lower frequency. The proposed control strategy eliminates conventional harmonic detectors by directly regulating the source current. Therefore, the computational complexity is greatly reduced and the performance of the APF is improved. A mathematic model has been developed based on the source currents. The corresponding controllers have been designed based on the sinusoidal internal model principle. The proposed control strategy can guarantee excellent compensation performance and stable operation after an extreme disturbance such as a short circuit fault. In addition, the proposed technique can selectively compensate specific harmonics. A 50kVA prototype APF is implemented in the laboratory to validate the feasibility and performance of the proposed control strategy.

An Improved One Cycle Control for Active Power Filters under Non-Ideal Voltage Conditions

Lei Wang,Chunguang Ren,Yu Yang,Xiaoqing Han,Peng Wang 전력전자학회 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.6

The one cycle control (OCC) scheme for active power filters (APFs) has shown excellent harmonic suppression and implementation simplicity. However, its real world application is limited because the non-ideal supply voltage for APFs can influence its performance so that the source currents are still distorted after compensation. This paper proposes a modified one cycle control (MOCC) scheme to improve the performance of three-phase shunt APFs under non-ideal supply voltage conditions. In this paper a detailed mathematical derivation has been presented and the key control law of the MOCC has been developed for adaption to the non-ideal supply voltages, following the control philosophy of simplicity. A relatively simple sequence filter is introduced to extract the harmonic components of supply voltages. The modified scheme can be easily implemented. The proposed control strategy has excellent performance and a 5kVA APF hardware platform has been implemented to validate the feasibility and performance of the proposed strategy.

영·유·아동의 정서 및 사회성발달 단계에 따른 부모-자녀 간 상호작용발달

왕효경(Wang Xiaoqing),성지영(Sung Ji Young),임은미(Lim Eun Mi) 전북대학교 교육문제연구소 2017 교육문제연구 Vol.23 No.1

아이가 태어나서부터 주변 환경과의 상호작용을 통해 정서 및 사회성발달이 이루어진다. 0-6세 아이에게는 부모와의 상호작용을 통해 이뤄졌고, 6-12세의 아동에 게는 부모와의 상호작용이 점점 줄어들어 또래와의 상호작용으로 이루어진다. 아이가 각 단계에서 접하는 환경이 다름에 따라 정서 및 사회성발달을 이루는 경로도 다르다. 각 단계의 특성이 다름으로 인해 부모가 아이를 양육하는 방식과 양육 관념도 다르고, 부모와의 상호작용 방식도 다르게 된다. 이런 발달적인 상호작용을 통해 아이가 성인으로 사회화 되는 동시에 부모도 사회성 성장이 이루어진다. 본 논문은 Erikson의 심리사회이론과 Havighurst의 인간발달과업 중의 정서와 관련된 발달과업이론을 기반으로 각 단계의 정서 및 사회성발달의 몇 가지 특성을 살펴보았다. 영유아기는 신뢰감과 자율성발달, 유아기는 주도성발달, 아동기는 근면성발달을 요구한다. 부모가 아동들의 요구를 민감하게 파악하고, 아동의 요구에 맞게 역할 수행을 해야 한다. 그리고 아동이 순조롭게 심리사회적 위기를 넘도록 부모가 자녀와의 상호작용에 대비하는 방법도 배워야 한다. 논의 및 결론에서는 발달적 부모-자녀 간 상호작용에 대비하는 여러 방법도 각 단계별로 제시하였다. Children develop their emotions and sociality through interaction with their surroundings from birth. Because children in different stages of development are exposed to different environments, emotional and social development paths to achieve are also different. Children aged 0-6 mainly interacted with their parents, while children aged 6-12 decreased their interaction with their parents and increased interaction with their peers. Therefore, different stages of children s emotional and social development also showed different characteristics, which determines the parenting style, parenting concepts and parent-child interaction should also make corresponding changes. Based on psycho-social development theory of Erikson, this paper analyzes the emotional and social developmental characteristics of children at different stages. Infant stage is mainly to the requirements of the development of sense of basic trust and sense of autonomy, early childhood is mainly to the requirements of dominant development, childhood is mainly to the requirements of the development of senses of industry. Parents should be sensitive to master and understand the requirements of the various stages of children development, to make the appropriate role changes. In addition, for the children to successfully through the psycho-social crisis, this paper puts forward the corresponding method on parent-child interaction.