On the mitigation of surf-riding by adjusting center of buoyancy in design stage

Yu, Liwei,Ma, Ning,Gu, Xiechong The Society of Naval Architects of Korea 2017 International Journal of Naval Architecture and Oc Vol.9 No.3

High-speed vessels are prone to the surf-riding in adverse quartering seas. The possibility of mitigating the surf-riding of the ITTC A2 fishing vessel in the design stage is investigated using the 6-DOF weakly non-linear model developed for surf-riding simulations in quartering seas. The longitudinal position of the ship's center of buoyancy (LCB) is chosen as the design parameter. The adjusting of LCB is achieved by changing frame area curves, and hull surfaces are reconstructed accordingly using the Radial Basis Function (RBF). Surf-riding motions in regular following seas for cases with different LCBs and Froude numbers are simulated using the numerical model. Results show that the surf-riding cannot be prevented by the adjusting of LCB. However, it occurs with a higher threshold speed when ship's center of buoyancy (COB) is moved towards stem compared to moving towards stern, which is mainly due to the differences on wave resistance caused by the adjusting of LCB.

On the mitigation of surf-riding by adjusting center of buoyancy in design stage

Liwei Yu,Ning Ma,Xiechong Gu 대한조선학회 2017 International Journal of Naval Architecture and Oc Vol.9 No.3

High-speed vessels are prone to the surf-riding in adverse quartering seas. The possibility of mitigating the surf-riding of the ITTC A2 fishing vessel in the design stage is investigated using the 6-DOF weakly non-linear model developed for surf-riding simulations in quartering seas. The longitudinal position of the ship's center of buoyancy (LCB) is chosen as the design parameter. The adjusting of LCB is achieved by changing frame area curves, and hull surfaces are reconstructed accordingly using the Radial Basis Function (RBF). Surf-riding motions in regular following seas for cases with different LCBs and Froude numbers are simulated using the numerical model. Results show that the surf-riding cannot be prevented by the adjusting of LCB. However, it occurs with a higher threshold speed when ship's center of buoyancy (COB) is moved towards stem compared to moving towards stern, which is mainly due to the differences on wave resistance caused by the adjusting of LCB.

Polyethylene Terephthalate/Carbon Fabric/Polyurethane Foam Sandwich Composites: Flame Retardance and Mechanical Properties

Liwei Wu,Jingyan Ban,Qian Jiang,Ting-Ting Li,Bing-Chiuan Shiu,Shih-Yu Huang,Ching-Wen Lou,Jia-Horng Lin 한국섬유공학회 2019 Fibers and polymers Vol.20 No.6

Polyethylene terephthalate (PET) nonwoven fabrics, carbon fabrics (CF), and flexible polyurethane (PU) foamsare made into novel sandwich composites using one-step molding. The flame retradance and mechanical properties of thesandwich composites are evaluated, examining the influences of the content of flame retardant agent (20, 30, 40, and 50 wt%)and areal density of PET panels (200, 300, and 400 g/m2). The test results show that the PET/CF/PU sandwich composites arerated flame retardant as V0 and do not generate melts. The failure mode of PET/CF/PU sandwich composites converts fromoverall fracture to layered fracture as a result of increasing the flame retardant agent. The tensile strength at break of PET/CF/PU sandwich composites with corresponding PET panels is 650 N for 200 g/m2, 928 N for 300 g/m2, and 1744 N for 400 g/m2,which are 42.63 %, 60.48 %, and 77.85 % greater than those of the PET/PU sandwich composites. Moreover, the burstingstrength of PET/CF/PU sandwich composites with corresponding PET panels is 3322 N for 200 g/m2, 3869 N for 300 g/m2,and 4978 N for 400 g/m2, which are 195 %, 180 %, and 143 % greater than those of the PET/PU sandwich composites.

Maritime Targets Tracking in Heavy-tailed Clutter With Unknown and Time-varying Density

Liwei Shi,Yu Kuang,Miaomiao He 제어·로봇·시스템학회 2024 International Journal of Control, Automation, and Vol.22 No.4

In order to solve the problem of maritime targets tracking in heavy-tailed sea clutter with unknown and time-varying clutter density, a multi-scan clutter sparsity estimator based amplitude-aided probability hypothesis density (MCSE-APHD) method is proposed in this paper. Firstly, the proposed method eliminates the targetoriginated measurements from multi-scan cumulative measurement set and estimates the spatial distribution density of clutter online. And the estimated clutter density parameter is fed to the tracker. Secondly, the amplitude-aided likelihood function as well as the estimated clutter parameter is established to update the Gaussian mixture posterior intensity of the state using the probability hypothesis density algorithm. The simulation results verify the effectiveness of the proposed algorithm.

Synthesis of Au Nanoparticles Functionalized 1D α-MoO3 Nanobelts and Their Gas Sensing Properties

Liwei Wang,Shaopeng Wang,Hao Fu,Yinghui Wang,Kefu Yu 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2018 NANO Vol.13 No.10

A novel sensor material of Au nanoparticles (NPs) functionalized 1D α-MoO3 nanobelts (NBs) was fabricated by a facile lysine-assisted approach. The obtained Au/α-MoO3 product was characterized by means of X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM) and energy dispersive X-ray (EDX), and X-ray photoelectron spectra (XPS). Then, in order to investigate the gas sensing performances of our samples, a comparative gas sensing study was carried out on both the α-MoO3 NBs before and after Au NPs decoration by using ethanol vapor as the molecular probe. The results turned out that, after the functionalization of Au NPs, the sensor exhibited improved gas-sensing characteristics than the pure α-MoO3, such as response and recovery time, optimal operating temperature (OT) and excellent selectivity. Take for example 200 ppm of ethanol, the response/ recovery times were 34 s/43 s and 5.7 s/10.5 s, respectively, while the optimal operating temperature (OT) was lower to 200 ℃ rather than 250 ℃. Besides, the functionalized sensor showed a higher response to ethanol at 200 ℃, and response was 1.6 times higher than the pure MoO3. The mechanism of such improved sensing properties was interpreted, which might be attributed to the spillover effect of Au NPs and the electronic metal-support interaction.

Enhanced Catalytic Ability of Candida rugosa Lipase Immobilized on Pore-enlarged Hollow Silica Microspheres and Cross-linked by Modified Dextran in Both Aqueous and Non-aqueous Phases

Liwei Ren,Honghua Jia,Min Yu,Wenzhong Shen,Hua Zhou,Ping Wei 한국생물공학회 2013 Biotechnology and Bioprocess Engineering Vol.18 No.5

Candida rugosa lipase (CRL) is one of the most widely used lipases. To enhance the catalytic abilities of CRL in both aqueous and non-aqueous phases, hollow silica microspheres (HSMSs) with a pore size of 18.07 nm were used as an immobilization support, and aldehydecontaining dextrans were employed to further cross-link the adsorbed CRL. In the experimental ranges examined,the loading amount of lipase linearly increased to 171 ±3.4 mgprotein/gsupport with the CRL concentration and all the adsorption equilibriums were reached within 30 min. After simple cross-linking, the tolerance to pH 4.0 ~ 8.0 as well as the thermal stability of immobilized CRL at 40 ~ 80oC were both substantially increased, and 82 ± 2.1% activity remaining after the sixth reuse. The immobilized CRL was successfully applied to the resolution of racemic ibuprofen in non-aqueous phase. The initial reaction rate increased by 1.4- and 3.6-fold compared with the rates of adsorbed and native lipases, respectively. Furthermore, the R-ibuprofen was obtained at ee > 93%, and the enantiomeric ratio reached E > 140 at the conversion of 50 ± 1.5% within 48 h.

Effects of the Charge Ions Strength on the Swelling of Organic–Inorganic Nanogels

Qin Yu,Xiangguo Lu,Jing Wang,Qi Guo,Liwei Niu 대한화학회 2016 Bulletin of the Korean Chemical Society Vol.37 No.7

The swelling behavior and swelling mechanism of hydrogels can be greatly affected by the charge strength of ions in them. To investigate such effects, we prepared two gels: a carboxylic acid gel (CAG) and a poly(2-acrylamide–methyl propane sulfonic acid) gel (SAG) based on starchy polyacrylamide (PAM) nanocomposite gels, both with montmorillonite, which underwent in situ intercalation, and used them as probes in swelling experiments. The equilibrium swelling rates (ESRs) of the hydrogels in both salt water and acidic water strongly depended on the charge strength of the ions in the chains. SAG had a higher ESR than CAG at the same mole ratio of polymer/water, which is attributed to the greater electrostatic repulsion between the strong electrolyte ions of SAG. Both water salinity and hydrogen ion contact of the hydrogels weakened ESR with the enhancement of charge ionic strength. The downward trend of ESR with increasing concentration of salt or hydrogen ions became weaker in SAG compared to CAG, which is attributed to the shielding and deprotonation effects of the strong electrolyte ions. Regarding the swelling mechanism, the chain relaxation occurred in neutral and acidic solutions for SAG and in neutral and weak acidic solutions for CAG, but water diffusion dominated in strong acidic solutions for CAG, leading to different swelling behaviors.

A pilot study on differential expression of microRNAs in the ventromedial prefrontal cortex and serum of sows in activity restricted crates or activity free pens

Guoan Yin,Liwei Guan,Langchao Yu,Dapeng Huang 아세아·태평양축산학회 2019 Animal Bioscience Vol.32 No.9

Objective: Physical activity restriction in sows may lead to behavioral abnormalities and affective disorders. However, the psychophysiological state of these sows is still unclear. As miRNAs can be used as effective markers of psychopathy, the present study aimed to assess the difference in microRNA expression between the long-term activity restricted sows and activity free sows, thus contributing to the understanding of abnormal sow behavior. Methods: Four dry sows (sixth parity, Large×White genetic line) were selected from activity restricted crates (RC) or activity free pens (FP) separately. microRNAs in the ventromedial prefrontal cortex (vMPFC) and serum were examined using real-time polymerase chain reaction, and the correlation between the miRNAs expressed in the vMPFC and serum was evaluated. Results: miR-134 (1.11 vs 0.84) and miR-1202 (1.09 vs 0.85) levels were higher in the vMPFC of the RC sows than in the FP sows (p<0.01). Furthermore, miR-132 (1.27 vs 1.08) and miR-335 (1.03 vs 0.84) levels were also higher in the RC sows than in FP sows (p<0.05); however, miR-135a, miR-135b, miR-16, and miR-124 levels were not different (p>0.05). The relative expression of serum miR-1202 was higher in the RC sows than in the FP sows (1.04 vs 0.54) (p<0.05), and there was a strong correlation (R = 0.757, p<0.05) between vMPFC and Serum levels of miR-1202. However, no significant difference was observed in miR-16 levels in the serum of the RC sows and FP sows (p>0.05). Conclusion: This pilot study demonstrates that long-term activity restriction in sows likely results in autism or other complex psychopathies with depression-like behaviors. These observations may provide new insights for future studies on abnormal behavior in sows and contribute to research on human psychopathy.

Hierarchical porous ECM scaffolds incorporating GDF-5 fabricated by cryogenic 3D printing to promote articular cartilage regeneration

Wu Jiang,Fu Liwei,Yan Zineng,Yang Yu,Yin Han,Li Pinxue,Yuan Xun,Ding Zhengang,Kang Teng,Tian Zhuang,Liao Zhiyao,Tian Guangzhao,Ning Chao,Li Yuguo,Sui Xiang,Chen Mingxue,Liu Shuyun,Guo Quanyi 한국생체재료학회 2023 생체재료학회지 Vol.27 No.00

In recent years, there has been significant research progress on in situ articular cartilage (AC) tissue engineering with endogenous stem cells, which uses biological materials or bioactive factors to improve the regeneration microenvironment and recruit more endogenous stem cells from the joint cavity to the defect area to promote cartilage regeneration.In this study, we used ECM alone as a bioink in low-temperature deposition manufacturing (LDM) 3D printing and then successfully fabricated a hierarchical porous ECM scaffold incorporating GDF-5.Comparative in vitro experiments showed that the 7% ECM scaffolds had the best biocompatibility. After the addition of GDF-5 protein, the ECM scaffolds significantly improved bone marrow mesenchymal stem cell (BMSC) migration and chondrogenic differentiation. Most importantly, the in vivo results showed that the ECM/GDF-5 scaffold significantly enhanced in situ cartilage repair.In conclusion, this study reports the construction of a new scaffold based on the concept of in situ regeneration, and we believe that our findings will provide a new treatment strategy for AC defect repair.

Enhanced Self-Biased Magnetoelectric Coupling in Laser-Annealed Pb(Zr,Ti)O₃ Thick Film Deposited on Ni Foil

Palneedi, Haribabu,Maurya, Deepam,Geng, Liwei D.,Song, Hyun-Cheol,Hwang, Geon-Tae,Peddigari, Mahesh,Annapureddy, Venkateswarlu,Song, Kyung,Oh, Yoon Seok,Yang, Su-Chul,Wang, Yu U.,Priya, Shashank,Ryu, American Chemical Society 2018 ACS APPLIED MATERIALS & INTERFACES Vol.10 No.13

<P>Enhanced and self-biased magnetoelectric (ME) coupling is demonstrated in a laminate heterostructure comprising 4 μm-thick Pb(Zr,Ti)O<SUB>3</SUB> (PZT) film deposited on 50 μm-thick flexible nickel (Ni) foil. A unique fabrication approach, combining room temperature deposition of PZT film by granule spray in vacuum (GSV) process and localized thermal treatment of the film by laser radiation, is utilized. This approach addresses the challenges in integrating ceramic films on metal substrates, which is often limited by the interfacial chemical reactions occurring at high processing temperatures. Laser-induced crystallinity improvement in the PZT thick film led to enhanced dielectric, ferroelectric, and magnetoelectric properties of the PZT/Ni composite. A high self-biased ME response on the order of 3.15 V/cm·Oe was obtained from the laser-annealed PZT/Ni film heterostructure. This value corresponds to a ∼2000% increment from the ME response (0.16 V/cm·Oe) measured from the as-deposited PZT/Ni sample. This result is also one of the highest reported values among similar ME composite systems. The tunability of self-biased ME coupling in PZT/Ni composite has been found to be related to the demagnetization field in Ni, strain mismatch between PZT and Ni, and flexural moment of the laminate structure. The phase-field model provides quantitative insight into these factors and illustrates their contributions toward the observed self-biased ME response. The results present a viable pathway toward designing and integrating ME components for a new generation of miniaturized tunable electronic devices.</P> [FIG OMISSION]</BR>