A study of hydroelastic behavior of hinged VLFS

Sun, Yonggang,Lu, Da,Xu, Jin,Zhang, Xiantao The Society of Naval Architects of Korea 2018 International Journal of Naval Architecture and Oc Vol.10 No.2

This paper introduces a new method to study the hydroelastic behavior of hinged Very Large Floating Structures (VLFSs). A hinged two-module structure is used to confirm the present approach. For each module, the hydroelasticity theory proposed by Lu et al. (2016) is adopted to consider the coupled effects of wave dynamics and structural deformation. The continuous condition at the connection position between two adjacent modules is also satisfied. Then the hydroelastic motion equation can be established and numerically solved to obtain the vertical displacement, force and bending moment of the hinged structure. The results calculated by the present new method are compared with those obtained using three-dimensional hydroelasticity theory (Fu et al., 2007), which shows rather good agreement.

A study of hydroelastic behavior of hinged VLFS

Yonggang Sun,Da Lu,Jin Xu,Xiantao Zhang 대한조선학회 2018 International Journal of Naval Architecture and Oc Vol.10 No.2

This paper introduces a new method to study the hydroelastic behavior of hinged Very Large Floating Structures (VLFSs). A hinged twomodule structure is used to confirm the present approach. For each module, the hydroelasticity theory proposed by Lu et al. (2016) is adopted to consider the coupled effects of wave dynamics and structural deformation. The continuous condition at the connection position between two adjacent modules is also satisfied. Then the hydroelastic motion equation can be established and numerically solved to obtain the vertical displacement, force and bending moment of the hinged structure. The results calculated by the present new method are compared with those obtained using three-dimensional hydroelasticity theory (Fu et al., 2007), which shows rather good agreement.

A second order analytical solution of focused wave group interacting with a vertical wall

Yonggang Sun,Xiantao Zhang 대한조선학회 2017 International Journal of Naval Architecture and Oc Vol.9 No.2

The interaction of focused wave groups with a vertical wall is investigated based on the second order potential theory. The NewWave theory, which represents the most probable surface elevation under a large crest, is adopted. The analytical solutions of the surface elevation, velocity potential and wave force exerted on the vertical wall are derived, up to the second order. Then, a parametric study is made on the interaction between nonlinear focused wave groups and a vertical wall by considering the effects of angles of incidence, wave steepness, focal positions, water depth, frequency bandwidth and the peak lifting factor. Results show that the wave force on the vertical wall for obliquely-incident wave groups is larger than that for normally-incident waves. The normalized peak crest of wave forces reduces with the increase of wave steepness. With the increase of the distance of focal positions from the vertical wall, the peak crest of surface elevation, although fluctuates, decreases gradually. Both the normalized peak crest and adjacent crest and trough of wave forces become larger for shallower water depth. For focused wave groups reflected by a vertical wall, the frequency bandwidth has little effects on the peak crest of wave elevation or forces, but the adjacent crest and trough become smaller for larger frequency bandwidth. There is no significant change of the peak crest and adjacent trough of surface elevation and wave forces for variation of the peak lifting factor. However, the adjacent crest increases with the increase of the peak lifting factor.

A second order analytical solution of focused wave group interacting with a vertical wall

Sun, Yonggang,Zhang, Xiantao The Society of Naval Architects of Korea 2017 International Journal of Naval Architecture and Oc Vol.9 No.2

The interaction of focused wave groups with a vertical wall is investigated based on the second order potential theory. The NewWave theory, which represents the most probable surface elevation under a large crest, is adopted. The analytical solutions of the surface elevation, velocity potential and wave force exerted on the vertical wall are derived, up to the second order. Then, a parametric study is made on the interaction between nonlinear focused wave groups and a vertical wall by considering the effects of angles of incidence, wave steepness, focal positions, water depth, frequency bandwidth and the peak lifting factor. Results show that the wave force on the vertical wall for obliquely-incident wave groups is larger than that for normally-incident waves. The normalized peak crest of wave forces reduces with the increase of wave steepness. With the increase of the distance of focal positions from the vertical wall, the peak crest of surface elevation, although fluctuates, decreases gradually. Both the normalized peak crest and adjacent crest and trough of wave forces become larger for shallower water depth. For focused wave groups reflected by a vertical wall, the frequency bandwidth has little effects on the peak crest of wave elevation or forces, but the adjacent crest and trough become smaller for larger frequency bandwidth. There is no significant change of the peak crest and adjacent trough of surface elevation and wave forces for variation of the peak lifting factor. However, the adjacent crest increases with the increase of the peak lifting factor.

Marine Geo-environmental Disaster: Field Survey and In-situ Long-term Observation

( Yonggang Jia ),( Cong Hu ),( Zhiwen Sun ),( Hong Zhang ),( Hongxian Shan ) 대한지질공학회 2019 대한지질공학회 학술발표회논문집 Vol.2019 No.2

Ocean exploitation has entered full ocean depth era. However, frequent marine geological disasters seriously restrict its development. Due to the complex marine engineering geology environment, in-situ observation has become an important means of submarine engineering survey. Based on the common types of marine geological disasters in marine engineering activities, this paper introduces the marine engineering geological survey and in-situ monitoring technology and its application from the perspective of marine engineering geological environment and dynamic action, so as to provide new ideas for the study of marine geological disasters in China.

A Coordinative Control Strategy for Power Electronic Transformer Based Battery Energy Storage Systems

Sun, Yuwei,Liu, Jiaomin,Li, Yonggang,Fu, Chao,Wang, Yi The Korean Institute of Power Electronics 2017 JOURNAL OF POWER ELECTRONICS Vol.17 No.6

A power electronic transformer (PET) based on the cascaded H-bridge (CHB) and the isolated bidirectional DC/DC converter (IBDC) is capable of accommodating a large scale battery energy storage system (BESS) in the medium-voltage grid, and is referred to as a power electronic transformer based battery energy storage system (PET-BESS). This paper investigates the PET-BESS and proposes a coordinative control strategy for it. In the proposed method, the CHB controls the power flow and the battery state-of-charge (SOC) balancing, while the IBDC maintains the dc-link voltages with feedforward implementation of the power reference and the switch status of the CHB. State-feedback and linear quadratic Riccati (LQR) methods have been adopted in the CHB to control the grid current, active power and reactive power. A hybrid PWM modulating method is utilized to achieve SOC balancing, where battery SOC sorting is involved. The feedforward path of the power reference and the CHB switch status substantially reduces the dc-link voltage fluctuations under dynamic power variations. The effectiveness of the proposed control has been verified both by simulation and experimental results. The performance of the PET-BESS under bidirectional power flow has been improved, and the battery SOC values have been adjusted to converge.

A Coordinative Control Strategy for Power Electronic Transformer Based Battery Energy Storage Systems

Yuwei Sun,Jiaomin Liu,Yonggang Li,Chao Fu,Yi Wang 전력전자학회 2017 JOURNAL OF POWER ELECTRONICS Vol.17 No.6

A power electronic transformer (PET) based on the cascaded H-bridge (CHB) and the isolated bidirectional DC/DC converter (IBDC) is capable of accommodating a large scale battery energy storage system (BESS) in the medium-voltage grid, and is referred to as a power electronic transformer based battery energy storage system (PET-BESS). This paper investigates the PET-BESS and proposes a coordinative control strategy for it. In the proposed method, the CHB controls the power flow and the battery state-of-charge (SOC) balancing, while the IBDC maintains the dc-link voltages with feedforward implementation of the power reference and the switch status of the CHB. State-feedback and linear quadratic Riccati (LQR) methods have been adopted in the CHB to control the grid current, active power and reactive power. A hybrid PWM modulating method is utilized to achieve SOC balancing, where battery SOC sorting is involved. The feedforward path of the power reference and the CHB switch status substantially reduces the dc-link voltage fluctuations under dynamic power variations. The effectiveness of the proposed control has been verified both by simulation and experimental results. The performance of the PET-BESS under bidirectional power flow has been improved, and the battery SOC values have been adjusted to converge.

Visual Tracking with Online Incremental Deep Learning and Particle Filter

Shuai Cheng,Yonggang Cao,Junxi Sun,Guangwen Liu 보안공학연구지원센터 2015 International Journal of Signal Processing, Image Vol.8 No.12

To solve the problem of tracking the trajectory of a moving object and learning a deep compact image representation in the complex environment, a novel robust incremental deep learning tracker is presented under the particle filter framework. The incremental deep classification neural network was composed of stacked denoising autoencoder, incremental feature learning and support vector machine to achieve the feature-extracting and classification of particle set. Deep learning is successfully taken to express the image representations obtained effectively. Unsupervised feature learning is used to learn generic image features and transfer learning transforms knowledge from offline training to the online tracking process. The incremental feature learning was consisted of adding features and merging features to online learn compact feature set. Linear support vector machine increases the discretion for target with similar appearance and is further tuned to adapt to appearance changes of the moving object. Compared with the state-of-the-art trackers in the complex environment, the results of experiments on variant challenging image sequences show that incremental deep learning tracker solves the problem of existent trackers more efficiently, it has better robust and more accurate, especially for occlusions, background clutter, illumination changes and appearance changes.

Zircon U-Pb geochronology, geochemistry, and Hf isotopic compositions of the trachyandesite in the Dong’an Au deposit, Lesser Xing’an Range, northeastern China

Gantian Li,Fengyue Sun,Bile Li,Yonggang Sun,Runtao Yu 한국지질과학협의회 2021 Geosciences Journal Vol.25 No.6

The Dong’an Au deposit is a large-sized epithermal Au deposit discovered in the Lesser Xing’an Range, Northeastern China. Intermediate–acid volcanic rocks (e.g., trachyandesite, andesite, dacite, rhyolite, and rhyolitic tuff) of the Lower Cretaceous Fuminghe Formation are the important surrounding rocks for Au mineralization in the Dong’an Au deposit. However, the relationship between the intermediate volcanic rocks and the acidic volcanic rocks is unclear. The authors present new geochemical, zircon U-Pb and Hf isotope data for the trachyandesites in the Dong’an Au deposit. The whole-rock geochemical data indicate that the trachyandesite samples are high-K calc-alkaline. They are enriched in LILEs (e.g., K, Rb, and Ba), LREEs, and incompatible elements (e.g., Th and U), but are depleted in HFSEs (e.g., Nb, Ta, P, and Ti), showing characteristics of volcanic arc magmas. They have low Mg# values (32.77–48.12), Cr, Ni, and Co contents. Zircons U-Pb dating of the trachyandesites from sample DA-N1 and DA-N2 yield weighted average ages of 108.0 ± 1.1 Ma (MSWD = 0.91) and 104.7 ± 4.3 Ma (MSWD = 17). In situ zircon Hf isotope analyses of the trachyandesites from sample DA-N1 and DA-N2 yield εHf(t) values of –3.2 – 1.2 and –2.3 – 2.6, and two-stage model age (TDM2) of 1372–1090 Ma and 1321–1009 Ma, respectively. These suggest the trachyandesite were derived from partial melting of the juvenile lower crust with involvement of the ancient crustal materials. Combined with previous geological and petrogeochemical characteristics of the Lower Cretaceous Fuminghe Formation volcanic rocks in the Dong’an Au deposit, the Fuminghe Formation volcanic rocks are believed to be comagmatic, and fractional crystallization played an important role in the differentiation of these volcanic rocks. They were likely formed during the retreat of the subducted Paleo-Pacific Plate.

Lightweight Intrusion Detection of Rootkit with VMI-Based Driver Separation Mechanism

( Chaoyuan Cui ),( Yun Wu ),( Yonggang Li ),( Bingyu Sun ) 한국인터넷정보학회 2017 KSII Transactions on Internet and Information Syst Vol.11 No.3

Intrusion detection techniques based on virtual machine introspection (VMI) provide high temper-resistance in comparison with traditional in-host anti-virus tools. However, the presence of semantic gap also leads to the performance and compatibility problems. In order to map raw bits of hardware to meaningful information of virtual machine, detailed knowledge of different guest OS is required. In this work, we present VDSM, a lightweight and general approach based on driver separation mechanism: divide semantic view reconstruction into online driver of view generation and offline driver of semantics extraction. We have developed a prototype of VDSM and used it to do intrusion detection on 13 operation systems. The evaluation results show VDSM is effective and practical with a small performance overhead.