Hydrogen production from water electrolysis: role of catalysts

Wang Shan,Lu Aolin,Zhong Chuan-Jian 나노기술연구협의회 2021 Nano Convergence Vol.8 No.4

As a promising substitute for fossil fuels, hydrogen has emerged as a clean and renewable energy. A key challenge is the efficient production of hydrogen to meet the commercial-scale demand of hydrogen. Water splitting electrolysis is a promising pathway to achieve the efficient hydrogen production in terms of energy conversion and storage in which catalysis or electrocatalysis plays a critical role. The development of active, stable, and low-cost catalysts or electrocatalysts is an essential prerequisite for achieving the desired electrocatalytic hydrogen production from water splitting for practical use, which constitutes the central focus of this review. It will start with an introduction of the water splitting performance evaluation of various electrocatalysts in terms of activity, stability, and efficiency. This will be followed by outlining current knowledge on the two half-cell reactions, hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), in terms of reaction mechanisms in alkaline and acidic media. Recent advances in the design and preparation of nanostructured noble-metal and non-noble metal-based electrocatalysts will be discussed. New strategies and insights in exploring the synergistic structure, morphology, composition, and active sites of the nanostructured electrocatalysts for increasing the electrocatalytic activity and stability in HER and OER will be highlighted. Finally, future challenges and perspectives in the design of active and robust electrocatalysts for HER and OER towards efficient production of hydrogen from water splitting electrolysis will also be outlined.

Zero-Current Phenomena Analysis of the Single IGBT Open Circuit Faults in Two-Level and Three-Level SVGs

Wang, Ke,Zhao, Hong-Lu,Tang, Yi,Zhang, Xiao,Zhang, Chuan-Jin The Korean Institute of Power Electronics 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.2

The fact that the reliability of IGBTs has become a more and more significant aspect of power converters has resulted in an increase in the research on the open circuit (OC) fault location of IGBTs. When an OC fault occurs, a zero-current phenomena exists and frequently appears, which can be found in a lot of the existing literature. In fact, fault variables have a very high correlation with the zero-current interval. In some cases, zero-current interval actually decides the most significant fault feature. However, very few of the previous studies really explain or prove the zero-current phenomena of the fault current. In this paper, the zero-current phenomena is explained and verified through mathematical derivation, based on two-level and three-level NPC static var generators (SVGs). Mathematical models of single OC fault are deduced and it is concluded that a zero-current interval with a certain length follows the OC faults for both two-level and NPC three-level SVGs. Both inductive and capacitive reactive power situations are considered. The unbalanced load situation is discussed. In addition, simulation and experimental results are presented to verify the correctness of the theoretical analysis.

Reliability-Based Specification on Critical Length of Highway Sections with Near-Maximum Grade

Lu Wang,Jian-Chuan Cheng,Yunlong Zhang 대한토목학회 2018 KSCE JOURNAL OF CIVIL ENGINEERING Vol.22 No.4

In China’s current highway design specifications, the length of an upgrade segment is strictly limited when its grade is greater thanor equal to 3%. For expressways in flat and rolling terrains, the design speed is commonly at 120 km/h [75 mph] and thecorresponding maximum grade length must not exceed 900 m. However, there is no specific length limitation on any grade segmentseven though some of them may be just slightly below the maximum grade of 3%. This paper presents a probabilistic method tospecify the proper critical segment lengths of Near-Maximum Grade (NMG) with a full consideration of expressway safety. Terminologically, the NMG in this paper refers to a set of longitudinal slopes with grades that are very close to the maximum grade of3%, such as grades at 2.9%, 2.8%, and 2.7%. A long section with NMG on Nanjing-Hangzhou Expressway was chosen as the studycase and its crash data, road geometry and vehicle operational performance were all carefully recorded. Reliability-based methodswere employed to process the derived data to specify the critical length for this highway section. The results show that China’sregulated values for grade lengths are slightly greater for trucks, partially attributed to poor dynamic performance including climbingand braking. Finally, a set of reliable limiting values for NMG section lengths are developed. These can provide more suitableparameters for highway design to achieve enhanced operational safety performance. The findings of this study are expected toprovide a practical reference for future revisions of highway design specifications in China.

The Physiological Occlusion of the Central Canal May Be a Prerequisite for Syringomyelia Formation

Chuan Jiang,Xinyu Wang,Chunli Lu,Qian Li,Longbing Ma,Wei Li,Shengyu Cui,Kang Li,Xiang Wang,Yuxin Feng,Fengzeng Jian 대한척추신경외과학회 2023 Neurospine Vol.20 No.4

Objective: Syringomyelia is a common central nervous system disease characterized by the dilation of the central canal (CC). Regarding the pathogenesis of syringomyelia, cerebrospinal fluid (CSF) circulation obstruction in the subarachnoid space (SAS) of the spinal cord has been widely accepted. However, clinical and animal studies on obstructing the CSF in SAS failed to form syringomyelia, challenging the theory of SAS obstruction. The precise pathogenesis remains unknown. Methods: We utilized an extradural compression rat model to investigate the pathogenesis underlying syringomyelia. Magnetic resonance imaging enabled detection of syringomyelia formation. To assess CSF flow within the SAS, Evans blue was infused into the cisterna magna. Histological analysis allowed morphological examination of the CC. Furthermore, CSF flow through the CC was traced using Ovalbumin Alexa-Flour 647 conjugate (OAF-647). Scanning electron microscopy (SEM) enabled visualization of ependymal cilia. Results: The findings showed that the dura mater below the compression segment exhibited lighter coloration relative to the region above the compression, indicative of partial obstruction within the SAS. However, the degree of SAS occlusion did not significantly differ between syringomyelia (SM-Y group) and those without (SM-N group). Intriguingly, hematoxylin and eosin staining and CSF tracing revealed occlusion of the CC accompanied by reduced CSF flow in the SM-Y group compared to SM-N and control groups. SEM images uncovered impairment of ependymal cilia inside the syringomyelia. Conclusion: CC occlusion may represent a physiological prerequisite for syringomyelia formation, while SAS obstruction serves to initiate disease onset. The impairment of ependymal cilia appears to facilitate progression of syringomyelia.

Zero-Current Phenomena Analysis of the Single IGBT Open Circuit Faults in Two-Level and Three-Level SVGs

Ke Wang,Hong-Lu Zhao,Yi Tang,Xiao Zhang,Chuan-Jin Zhang 전력전자학회 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.2

The fact that the reliability of IGBTs has become a more and more significant aspect of power converters has resulted in an increase in the research on the open circuit (OC) fault location of IGBTs. When an OC fault occurs, a zero-current phenomena exists and frequently appears, which can be found in a lot of the existing literature. In fact, fault variables have a very high correlation with the zero-current interval. In some cases, zero-current interval actually decides the most significant fault feature. However, very few of the previous studies really explain or prove the zero-current phenomena of the fault current. In this paper, the zero-current phenomena is explained and verified through mathematical derivation, based on two-level and three-level NPC static var generators (SVGs). Mathematical models of single OC fault are deduced and it is concluded that a zero-current interval with a certain length follows the OC faults for both two-level and NPC three-level SVGs. Both inductive and capacitive reactive power situations are considered. The unbalanced load situation is discussed. In addition, simulation and experimental results are presented to verify the correctness of the theoretical analysis.

Hybrid Scheduling and Quantized Output Feedback Control for Networked Control Systems

Tengli Wang,Chuan Zhou,Hui Lu,Junda He,Jian Guo 제어·로봇·시스템학회 2018 International Journal of Control, Automation, and Vol.16 No.1

A novel co-design scheme of hybrid scheduling strategy, adaptive logarithmic quantizer and dynamic robust H-infinity output feedback controller for a class of networked control system (NCS)with communication constraints and time delay is proposed. The hybrid scheduling scheme integrates dead zone scheduling and Try Once Discard (TOD) scheduling so as to get the stronger adaptability and flexibility than the single scheduling. In this scheme, dead zone scheduling which updates the threshold according to mode-dependent control strategy is used for single node of NCS to reduce the network bandwidth utilization while TOD scheduling is used for the whole node of NCS in order to meet the requirements of communication constraints and guarantee the overall system performance.We develop the integrated design for the hybrid scheduling strategy, adaptive quantizer and dynamic robust output feedback controller to maintain asymptotic stability of the closed-loop NCS by using the multiple-Lyapunov function and switched system theory. The proposed method can improve the the quality of service (QoS) meanwhile ensure the quality of control (QoC) of overall systems, which make a better trade-off between network utilization and control performance. An simulation example demonstrates the efficiency of the proposed method.

Experimental investigation on flow field around a flapping plate with single degree of freedom

Hanyu Wang,Chuan Lu,Wenhai Qu,Jinbiao Xiong Korean Nuclear Society 2023 Nuclear Engineering and Technology Vol.55 No.6

Undesirable flapping motion of discs can cause the failure of swing check valves in nuclear passive safety systems. Time-resolved particle image velocimetry (PIV) was employed to investigate the flow characteristics around a free-to-rotate plate and the motion response, with the Reynolds numbers, based on the hydraulic diameter of the channel, from 1.32 × 10⁴ to 3.95 × 10⁴. Appreciable flapping motion (±3.52°) appeared at the Reynolds number of 2.6 × 10⁴ with the frequency of 5.08 Hz. In the low-Reynolds-number case, the plate showed negligible flapping. In the high-Reynolds-number case, the deflection angle increased with reduced flapping amplitude. The torque from the fluid determined the flapping amplitude. In the low-Reynolds-number case, Karman vortices were absent. With increasing Reynolds numbers, Karman vortices developed behind the plate with larger deflection angles. Strong interaction between the wake flow from the leading and trailing edge of the plate was observed. Based on power spectrum density (PSD) analysis, the vortex shedding frequency coincided with the flapping frequency, and the amplitude was positively correlated to the strength of the vortices. Proper orthogonal decomposition (POD) modes evince that, in the case of appreciable motion, coherent structures exhibited a larger spatial scale, enhancing the magnitude of the external torque on the plate.

Purification and Characterization of Chitinase from a New Species Strain, Pseudomonas sp. TKU008

( San Lang Wang ),( Bo Shyun Lin ),( Tzu Wen Liang ),( Chuan Lu Wang ),( Pei Chen Wu ),( Je Ruei Liu ) 한국미생물 · 생명공학회 2010 Journal of microbiology and biotechnology Vol.20 No.6

Modelling of effective irradiation swelling for inert matrix fuels

Zhang, Jing,Wang, Haoyu,Wei, Hongyang,Zhang, Jingyu,Tang, Changbing,Lu, Chuan,Huang, Chunlan,Ding, Shurong,Li, Yuanming Korean Nuclear Society 2021 Nuclear Engineering and Technology Vol.53 No.8

The results of effective irradiation swelling in a wide range of burnup levels are numerically obtained for an inert matrix fuel, which are verified with DART model. The fission gas swelling of fuel particles is calculated with a mechanistic model, which depends on the external hydrostatic pressure. Additionally, irradiation and thermal creep effects are included in the inert matrix. The effects of matrix creep strains, external hydrostatic pressure and temperature on the effective irradiation swelling are investigated. The research results indicate that (1) the above effects are coupled with each other; (2) the matrix creep effects at high temperatures should be involved; and (3) ranged from 0 to 300 MPa, a remarkable dependence of external hydrostatic pressure can be found. Furthermore, an explicit multi-variable mathematic model is established for the effective irradiation swelling, as a function of particle volume fraction, temperature, external hydrostatic pressure and fuel particle fission density, which can well reproduce the finite element results. The mathematic model for the current volume fraction of fuel particles can help establish other effective performance models.

Optimization Design of Stainless Steel Stamping Multistage Pump Based on Orthogonal Test

Weidong, Shi,Chuan, Wang,Weigang, Lu,Ling, Zhou,Li, Zhang Korean Society for Fluid machinery 2010 International journal of fluid machinery and syste Vol.3 No.4

Stainless steel stamping multistage pump has become the mainstream of civil multi-stage pump. Combined with the technological features of stamping and welding pump, the studies of design for hydraulic parts of pump were come out. An $L_{18}$($3^7$)orthogonal experiment was designed with seven factors and three values including blade inlet angle, impeller outer diameter, guide vane blade number, etc. 18 plans were designed. The two stage of whole flow field on stainless steel stamping multistage pump at design point for design was simulated by CFD. According to the test result and optimization design with experimental research, the trends of main parameters which affect hydraulic performance were got. After being manufactured and tested, the efficiency of the optimal model pump reaches 61.36% and the single head is more than 4.8 m. Compared with the standard efficiency of 53%, the design of the stainless steel stamping pump is successful. The result would be instructive to the design of Stainless steel stamping multistage pump designed by the impeller head maximum approach.