Simulation and assessment of gas dispersion above sea from a subsea release: A CFD-based approach

Xinhong Li,Guoming Chen,Renren Zhang,Hongwei Zhu,Changhang Xu 대한조선학회 2019 International Journal of Naval Architecture and Oc Vol.11 No.1

This paper presents a comprehensive simulation and assessment of gas dispersion above sea from a subsea release using a Computational Fluid Dynamics (CFD) approach. A 3D CFD model is established to evaluate the behavior of flammable gas above sea, and a jack-up drilling platform is included to illustrate the effect of flammable gas cloud on surface vessels. The simulations include a matrix of scenarios for different surface release rates, distances between surface gas pool and offshore platform, and wind speeds. Based on the established model, the development process of flammable gas cloud above sea is predicted, and the dangerous area generated on offshore platform is assessed. Additionally, the effect of some critical factors on flammable gas dispersion behavior is analyzed. The simulations produce some useful outputs including the detailed parameters of flammable gas cloud and the dangerous area on offshore platform, which are expected to give an educational reference for conducting a prior risk assessment and contingency planning.

Simulation and assessment of gas dispersion above sea from a subsea release: A CFD-based approach

Li, Xinhong,Chen, Guoming,Zhang, Renren,Zhu, Hongwei,Xu, Changhang The Society of Naval Architects of Korea 2019 International Journal of Naval Architecture and Oc Vol.11 No.1

This paper presents a comprehensive simulation and assessment of gas dispersion above sea from a subsea release using a Computational Fluid Dynamics (CFD) approach. A 3D CFD model is established to evaluate the behavior of flammable gas above sea, and a jack-up drilling platform is included to illustrate the effect of flammable gas cloud on surface vessels. The simulations include a matrix of scenarios for different surface release rates, distances between surface gas pool and offshore platform, and wind speeds. Based on the established model, the development process of flammable gas cloud above sea is predicted, and the dangerous area generated on offshore platform is assessed. Additionally, the effect of some critical factors on flammable gas dispersion behavior is analyzed. The simulations produce some useful outputs including the detailed parameters of flammable gas cloud and the dangerous area on offshore platform, which are expected to give an educational reference for conducting a prior risk assessment and contingency planning.

A soybean plastidic ATP/ADP transporter gene, GmAATP, is involved in carbohydrate metabolism in transgenic Arabidopsis

Feibing Wang,Xinhong Chen,Fan Zhang,Yuan Niu,Yuxiu Ye,Sitong Qi,Qing Zhou 한국식물생명공학회 2017 Plant biotechnology reports Vol.11 No.3

The plastidic ATP/ADP transporter (AATP) imports adenosine triphosphate (ATP) from the cytosol into plastids, resulting in the increase of the ATP supply to facilitate anabolic synthesis in heterotrophic plastids of dicotyledonous plants. The regulatory role of GmAATP from soybean in increasing starch accumulation has not been investigated. In this study, a gene encoding the AATP protein, named GmAATP, was successfully isolated from soybean. Transient expression of GmAATP in Arabidopsis protoplasts and Nicotiana benthamiana leaf epidermal cells revealed the plastidic localization of GmAATP. Its expression was induced by exogenous sucrose treatment in soybean. The coding region of GmAATP was cloned into a binary vector under the control of 35S promoter and then transformed into Arabidopsis to obtain transgenic plants. Constitutive expression of GmAATP significantly increased the sucrose and starch accumulation in the transgenic plants. Real-time quantitative PCR (qRT-PCR) analysis showed that constitutive expression of GmAATP up-regulated the expression of phosphoglucomutase (AtPGM), ADP-glucose pyrophosphorylase (AGPase) small subunit (AtAGPase-S1 and AtAGPase-S2), AGPase large subunit (AtAGPase-L1 and AtAGPase-L2), granule-bound starch synthase (AtGBSS I and AtGBSS II), soluble starch synthases (AtSSS I, AtSSS II, AtSSS III, and AtSSS IV), and starch branching enzyme (AtSBE I and AtSBE II) genes involved in starch biosynthesis in the transgenic Arabidopsis plants. Meanwhile, enzymatic analyses indicated that the major enzymes (AGPase, GBSS, SSS, and SBE) involved in the starch biosynthesis exhibited higher activities in the transgenic plants compared to the wild type (WT). These findings suggest that GmAATP may improve starch content of Arabidopsis by up-regulating the expression of the related genes and increasing the activities of the major enzymes involved in starch biosynthesis. All these results suggest that GmAATP could be used as a candidate gene for developing high starch-accumulating plants as alternative energy crops.

Power Flow Management in Hybrid Electric Vehicles

C. Purushothama,Xinhong Chen,Le Duc Chien,Jae Ou Chae,Bong Soo Kim 한국자동차공학회 2007 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-

Hybrid electrical vehicles are very popular due to their extended operating range, reduced emission, improved fuel economy and rapid refueling. They are powered by an internal combustion engine and an electrical motor which driven by a battery. Battery is charged either by the engine or by ‘regenerative’ braking, which otherwise dissipated in the form of heat to the atmosphere. In order to realize the best use of hybrid vehicles, an optimal power distribution between the engine and battery is required. In this paper dynamic programming technique and rule-based control methods are discussed to develop a power controller which would control the power distribution. Dynamic programming technique cannot be applied for real time applications due to their preview nature and computational complexity. But it is suggested that it can be used to improve efficiency of rule-based control method.

Effect of gas composition on dispersion characteristics of blowout gas on offshore platform

Yang, Dongdong,Chen, Guoming,Shi, Jihao,Li, Xinhong The Society of Naval Architects of Korea 2019 International Journal of Naval Architecture and Oc Vol.11 No.2

Gas composition has a significant impact on the dispersion behavior and accumulation characteristics of blowout gas. However, few public studies has investigated the corresponding effect of gas composition. Therefore, this study firstly builds the FLACS-based numerical model about an offshore drilling platform. Then several scenarios by varying the composition of blowout gas are simulated while the scenario with the composition of "Deepwater Horizon" accident is regarded as the benchmark. Furthermore, the effects of the gas composition on the flammable cloud volume, the influenced area of flammable cloud, the influenced area of hydrogen sulfide and the critical time of the hydrogen sulfide spreading to the living area are analyzed. The results demonstrate that gas composition is a driving factor for dispersion characteristics of blowout gas. All the results can give support to reduce the risk of the similar accidents incurred by real blowouts.

Surface Dielectric Barrier Discharge for Generating Negative Oxygen Ions

Menglei Zheng,Wei Wei,Xinhong Chen,Hui Wang,Guangxun Yu,Jae-Ou Chae 한국자동차공학회 2007 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-

In this study, two types of surface dielectric barrier discharge (DBD) reactors were examined at the conditions of 4.24 ㎸ and 356 ㎐, in order to find out the effect of different reactor configurations on producing negative oxygen ions. And the results showed that the ideal configuration of surface DBD reactor should be with external tips on its electrode. In the following step, the electrical properties of surface dielectric barrier discharge in atmosphere pressure have been investigated experimentally by changing duty ratio from 25% to 50% but keeping operation voltage and frequency in constant. The results indicated that the surface DBD reactor showed better characteristics for generation of negative oxygen ions when duty ratio was 50%.

Effect of gas composition on dispersion characteristics of blowout gas on offshore platform

Dongdong Yang,Guoming Chen,Jihao Shi,Xinhong Li 대한조선학회 2019 International Journal of Naval Architecture and Oc Vol.11 No.2

Gas composition has a significant impact on the dispersion behavior and accumulation characteristics of blowout gas. However, few public studies has investigated the corresponding effect of gas composition. Therefore, this study firstly builds the FLACS-based numerical model about an offshore drilling platform. Then several scenarios by varying the composition of blowout gas are simulated while the scenario with the composition of “Deepwater Horizon” accident is regarded as the benchmark. Furthermore, the effects of the gas composition on the flammable cloud volume, the influenced area of flammable cloud, the influenced area of hydrogen sulfide and the critical time of the hydrogen sulfide spreading to the living area are analyzed. The results demonstrate that gas composition is a driving factor for dispersion characteristics of blowout gas. All the results can give support to reduce the risk of the similar accidents incurred by real blowouts.

Effective replacement carburetor by compact Port Fuel Injection system in small motorcycle engine

Le Duc Chien,C. Purushothama,Chen Xinhong,Sim Ju Hyuen,Woohyung Kim,Chae Jae Ou 한국자동차공학회 2007 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-

Port Fuel Injection (PFI) was developed in 80s for automotive industry in order to improve engine performance and control effectively emission. It is now used widely in modem cars and some kinds of sport motorcycle. To take advantage of electronic, the premix of air-fuel and combustion process can be programmed and controlled very precisely. Therefore, emission and performance of engine can be improved significantly regarding to different working conditions. One of the main reason of PFI technology that makes it not popular on motorcycle is its complexity and high cost. This paper reports our recent efforts to develop a new and compact PFI system that can replace the in-used carburetor easily with less extra modification. The mixing process, included fuel injection timing, throttle shape design and parameters of ignition were all investigated. We minimized the number of sensors, built a new function to determine the crankshaft position therefore avoid to modify flywheel as previous experiments.

A Basic Study on Regeneration System using Plasma for Diesel Particulate Filter

Ruiqiang Liu(류서강),Jae-Ou Chae(채재우),Yong-Hwan Kwak(곽용환),Xinhong Chen(진신홍) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.6

Diesel Particulate Filter (DPF) is the most widely used method to control particulate emissions of diesel engine these days. However, DPF needs periodical regeneration because of soot deposition. Electric discharge plasma, with its strong oxidation characteristics can be utilized in the regeneration process even at lower exhaust temperatures, and the present study also confirmed that the regeneration of DPF was realized when the temperature was elevated from 200℃. Plasma oxidizes NO in the exhaust to NO<SUB>2</SUB> and NO<SUB>2</SUB> in turn oxidizes soot in presence of oxygen to release CO and CO<SUB>2</SUB>. The advantage with plasma regeneration is it proceeds at a lower temperature at which no damage to DPF can happen. Initial experiments were conducted on optimizing NO oxidation to NO<SUB>2</SUB> using plasma reactor. In the next step, regeneration of DPF was carried out. Different parameters such as applied high voltage and gas temperature are studied.

A R2R3-type MYB transcription factor gene from soybean, GmMYB12, is involved in flavonoids accumulation and abiotic stress tolerance in transgenic Arabidopsis

Feibing Wang,Xuqin Ren,Fan Zhang,Mingyang Qi,Huiyun Zhao,Xinhong Chen,Yuxiu Ye,Jiayin Yang,Shuguang Li,Yi Zhang,Yuan Niu,Qing Zhou 한국식물생명공학회 2019 Plant biotechnology reports Vol.13 No.3

The R2R3-type MYB transcription factors have been shown to increase flavonoids accumulation by regulating the expression of key enzyme genes related to flavonoid biosynthesis pathway. However, the roles and underlying mechanisms of the soybean GmMYB12 gene in regulation of flavonoids accumulation and tolerance to abiotic stresses are rarely known. In the present study, the GmMYB12 gene was isolated and its function was characterized. Sequence and yeast one-hybrid analyses showed that GmMYB12 contained two MYB domains and belonged to R2R3-MYB protein with transactivation activity. Subcellular localization analysis in onion epidermal cells indicated that GmMYB12 was localized to the nucleus. Overexpression of GmMYB12 increased the production of downstream flavonoids and the expression of related genes in the flavonoid biosynthesis pathway. It also improved resistance to salt and drought stresses during seed germination, root development, and growing stage. Further component and enzymatic analyses showed significant increases of proline content, pyrroline-5-carboxylate synthase (P5CS), superoxide dismutase (SOD), and peroxidase (POD) activities, as well as significant reduction of H2O2 and malonaldehyde (MDA) content under salt and drought stresses in transgenic plants. Meanwhile, the expression level of AtP5CS, AtSOD and AtPOD genes was up-regulated against salt and drought stresses. Together, our finding indicated that changing the expression level of GmMYB12 in plants alters the accumulation of flavonoids and regulates plantlet tolerance to abiotic stress by regulating osmotic balance, protecting membrane integrity and maintaining ROS homeostasis. The GmMYB12 gene has the potential to be used to increase the content of valuable flavonoids and improve the tolerance to abiotic stresses in plants