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.

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.

Second-Order Nonlinear Disturbance Observer Based Adaptive Disturbance Rejection Control for PMSM in Electric Vehicles

Yang Chengshun,Hua Tao,Dai Yuchen,Huang Xiaoning,Zhang Dongdong 대한전기학회 2023 Journal of Electrical Engineering & Technology Vol.18 No.3

In this paper, a high-performance nonlinear control technique is presented to address the robust anti-disturbance speed tracking problem for permanent magnet synchronous motors (PMSM) in electric vehicles. In the first step, the dynamic model of PMSM is established, and the controller is designed based on backstepping control. Additionally, consider eliminating the differential noise of the virtual controller and approving the virtual control rate and its derivative through the command filter in order to avoid complicated high-order derivatives. Then, based on the PMSM model, an improved model reference adaptive system (MRAS) is proposed to account for unknown parameter perturbation. Besides, in order to improve the anti-interference capability of the system during operation, a second-order nonlinear disturbance observer model is developed, and the robustness of the system is improved by combining the model with linear sliding mode control. Finally, the stability of the system is established using Lyapunov stability criteria, and the hardware-in-the-loop platform is established to demonstrate that the controller in this paper has excellent anti-interference abilities and robustness.

Measurement and correlation of phase equilibria in aqueous two-phase systems containing ionic liquid ([EOMiM]Br) and potassium citrate/ammonium citrate/potassium tartrate at different temperatures

Dongdong Wang,Yang Lu,Zhuo Sun,Wei Liang,Dongshu Sun,Changli Qi,ChengZhuo Sheng,Xiaopeng Yu 한국화학공학회 2020 Korean Journal of Chemical Engineering Vol.37 No.2

An aqueous two-phase system (ATPS) containing an ionic liquid (1-(2-methoxyethyl)-3-methylimidazolium bromide) and three organic salts (K3C6H5O7, (NH4)3C6H5O7, and K2C4H4O6) at different temperatures was designed. Binodal data were correlated using two empirical equations, and tie-line data were fit with the utilization of Bancroft and Othmer-Tobias equations. In the systems investigated, three conclusions were drawn from the study of the phase-forming ability of salt through effective excluded volume, Gibbs free energy of ions, and the phase diagram. First, if the same cations of salt were present, the ability of salt to form phases increased with increasing valence of the anion. Second, the larger the effective excluded volume, the stronger the aforementioned ability of salt in forming phases. Third, salt had more ability to form phases if cations (or anions) contained in the salt possessed higher negative Gibbs free energy when the cation (anion) of the salt was the same. The effect of temperature on ATPSs was also investigated. It was found that it was easier to form ATPSs at lower temperature, and the tie-line slope showed growing absolute values as the temperature was decreased.

Asymmetric coaxial three‑coil wireless power transmission system optimization

Dongdong Zhang,Xuesong Li,Jie Yang,Xiang Li,Thomas Wu 전력전자학회 2023 JOURNAL OF POWER ELECTRONICS Vol.23 No.9

With the rapid development of wireless power transmission (WPT) technology and the demand for a wide range of applications, the common two-coil system is becoming increasingly mature. However, the monotonous structure of two-coil systems limits their development. By incorporating relay coils, the distance of power transmission, efficiency, and electromagnetic field (EMF) leakage can be effectively improved. In this paper, the three-coil system is analyzed, and the relay coil parameters are optimized by an evolutionary algorithm. After that, based on the coil optimization, the compensation capacitance of the relay coil is analyzed and an analytical formula of the compensation capacitance of the optimized relay coil is obtained. The results show that the parameter-optimized system reduces current by 86.9%, increases efficiency by 10%, and suppresses EMF leakage by 18 dB. Meanwhile, the capacitor optimization further improves the transmission efficiency of the system.

Comparison of SDE and SPME for the analysis of volatile compounds in butters

Yang Liu,Yunna Wang,Dongdong Yuan,Yan Li,Liebing Zhang 한국식품과학회 2020 Food Science and Biotechnology Vol.29 No.1

The current study aimed to compare the effectiveness of two extraction techniques, namely simultaneous distillation–extraction (SDE) and solid-phase microextraction (SPME), in evaluating key aroma compounds in butters. Volatile compounds’ contributions to butter flavors were evaluated employing both odor active values (OAVs) and gas chromatography olfactometry (GC-O). The results showed that the species of volatile compounds detected by the two techniques were almost the same, whereas their volatile profiles were obviously different. Using SDE method, methyl ketones took up the largest proportion of the volatile compounds, followed by fatty acids. Using SPME method, the most abundant compounds were the fatty acids, followed by lactones. More methyl ketones were detected in the SDE extract owing to lipid degradation as a consequence of the high temperature during extraction. Lactones were considered to be the key aroma compounds, especially d-decalactone, which was identified by both OAVs and GC-O.

Effects of Frequency and Amplitude of Local Dynamic Hump and Inlet Turbulence Intensity on Flow Separation Control in Low-Pressure Turbine

Rongfei Yang,Hao Wang,Dongdong Zhong,Ning Ge 한국항공우주학회 2023 International Journal of Aeronautical and Space Sc Vol.24 No.3

Dynamic hump is an active control method, which has been proved to be able to suppress laminar flow separation on the suction surface of high-loaded low-pressure turbine (LPT) blades at low Reynolds number (Re). This paper further discusses the effectiveness of dynamic hump with different parameters for flow separation control. The Pak-B cascade working at Re = 25,000 was selected as the research object, and a small-sized two-dimensional dynamic hump designed in a half-sinusoidal configuration was placed just upstream of the peak velocity point on the suction surface. At inlet free-stream turbulence intensity (FSTI or Tu) of 1.5%, the controlled cascade loss and flow mechanism under different hump-oscillating frequency and amplitude was numerically analyzed in detail. The results show that the development characteristics of vortices/separation bubbles attached to the suction surface of the blade were significantly changed under the influence of the dynamic hump, which contributed to the variations of cascade loss accordingly. When the separation bubble at the trailing edge of the hump was forced to form shedding vortices, the large-sized separation bubble on suction surface of uncontrolled cascade was replaced by small-sized vortices with a certain spacing, thus inhibited the flow separation. The increase in amplitude and frequency of hump promote the formation of shedding vortices at the trailing edge of the hump. The optimal amplitude should be slightly less than the local boundary layer thickness at the position of hump on the uncontrolled cascade. Under the optimal hump amplitude, the effective hump-oscillating frequency is 50–250 Hz, which is approximately 0.5–2.7 times of the characteristic frequency defined by blade exit velocity and the distance between the hump trailing edge and the blade trailing edge. When inlet FSTI of the controlled cascade is reduced from 1.5 to 0.08%, the profile loss is approximately unchanged due to the same characteristics of the boundary layer in the hump region and upstream.

A Fiber Spool’s Vibration Sensitivity Optimization Based on Orthogonal Experimental Design

Jing Gao,Linbo Zhang,Dongdong Jiao,Guanjun Xu,Xue Deng,Qi Zang,Honglei Yang,Ruifang Dong,Tao Liu,Shougang Zhang 한국광학회 2024 Current Optics and Photonics Vol.8 No.1

A fiber spool with ultra-low vibration sensitivity has been demonstrated for the ultra-narrowlinewidth fiber-stabilized laser by the multi-object orthogonal experimental design method, which can achieve the optimization object and analysis of influence levels without extensive computation. According to a test of 4 levels and 4 factors, an L 16 (4 4 ) orthogonal table is established to design orthogonal experiments. The vibration sensitivities along the axial and radial directions and the normalized sums of the vibration sensitivities are determined as single objects and comprehensive objects, respectively. We adopt the range analysis of object values to obtain the influence levels of the four design parameters on the single objects and the comprehensive object. The optimal parameter combinations are determined by both methods of comprehensive balance and evaluation. Based on the corresponding fractional frequency stability of ultra-narrow-linewidth fiber-stabilized lasers, we obtain the final optimal parameter combination A3B1C2D1, which can achieve the fiber spool with vibration sensitivities of 10 −12 /g magnitude. This work is the first time to use an orthogonal experimental design method to optimize the vibration sensitivities of fiber spools, providing an approach to design the fiber spool with ultra-low vibration sensitivity.

Over-expression of PTEN on proliferation and apoptosis in canine mammary tumors cells

Jinjin Tong,Hua Zhang,Dongdong Sun,Yingxue Wang,Chao Yang,Yun Liu 한국통합생물학회 2016 Animal cells and systems Vol.20 No.6

Phosphatase and tensin homolog (PTEN) is an important tumor-suppressor gene which constitutes an important PI3K/Akt pathway by regulating the signaling of multiple biological processes, including apoptosis, metabolism, cell proliferation, and cell growth has been gaining increasing attention. However, the role of PTEN in regulating apoptosis of canine mammary tumors cells still needs further investigation. In this experiment, the effect of PTEN on proliferation and apoptosis in canine mammary tumors (CMT) cells was analyzed. As a result, gene and protein expression levels of apoptosis-related genes were detected. Eukaryotic expression vector pcDNA3.1+-PTEN were successfully constructed and stably transferred into canine CMT cells after geneticin (G418) selection. After pcDNA3.1+-PTEN transfection, compared with control group, the cells proliferation was inhibited and the cell apoptosis was increased in CMT cells. The expression of p-Akt was decreased and the apoptosis-related genes, such as caspase-3, caspase- 9, and Bax, were increased. These data serve to demonstrate the function of PTEN on apoptosis and gene regulatory in PI3K/Akt pathway in CMT cells. Collectively, our data link the tumorsuppressor activities of PTEN to the machinery controlling cell cycle through the modulation of signaling molecules whose signal target is the functional inactivation of the apoptosis gene product.

Advanced Diagnosis of Armature Winding Short-Circuit Faults in Variable Flux Reluctance Machines Using Information Fusion on Mechanical and Electrical Signals

Zhao Yao,Zhao Zhibo,Lin Shunfu,Yang Fan,Li Dongdong 대한전기학회 2024 Journal of Electrical Engineering & Technology Vol.19 No.4

Variable fl ux reluctance machines can be adopted in the fi eld of built-in starter generator for aero-engine. It is critical to achieve reliable protection of the power generation system in harsh environments. The single signal makes it diffi cult to identify the initial fault accurately due to the little impact by a small-turn short-circuit on the electromagnetic fi eld. Thus, this paper proposes a novel framework for multi-source information fusion fault diagnosis in VFRMs by extracted current signals manually and vibration signals automatically. Firstly, the armature winding short-circuit fault characteristics of the current and vibration signals in the VFRM are analyzed. Secondly, a multi-source fusion framework based on a kernel extreme learning machine combined with a multiscale convolutional neural network is presented according to the structural characteristics of the VFRM. Then, the Dempster-Shafer evidence theory is applied for achieving decision-level fusion. Finally, a four-phase 8/10-pole VFRM prototype with diff erent AWSC faults is used to validate the proposed method. The results indicate that the fault diagnosis rate of the proposed method is 97.28%, which is 10.37% and 3.7% higher than vibration and current signals, respectively. It is more reliable and eff ective to identify diff erent AWSC faults accurately in the early stages.