Numerical investigation on the dynamic behaviors of turbine valve disc–seat impact at low velocity

Jianfeng Mao,Wei Zhe Wang,Junhui Zhang,Ying Zheng Liu 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.2

In this study, the dynamic behaviors on a valve seat subjected to the impact of the valve disc at low velocities were investigated by usingnumerical analysis with finite element method. The impact damage of the valve disc against seat was evaluated through a threedimensionaldynamic explicit calculation. The parameters considered in the simulations were impact velocity, disc obliquity, aspect ratio,and contact area ratio. The model for impact calculation was implemented in the code ABAQUS, which is based on the constitutiveequation and fracture strain equation of Johnson and Cook, as well as on continuum damage mechanics. The distribution of damagecaused by the impact was computed and discussed. The impact damage of the valve disc was minimized when the disc obliquity wasapproximately 40°. The effects of variation of selected design parameters on dynamic behaviors were discussed. The best design parameterswere proposed, which served as a guide for future valve design.

The improvement effect of surfactants on hydrogenation at condition containing water for Cu/SiO2 catalysts

Zheng Chen,Xueying Zhao,Shuwei Wei,Dengfeng Wang,Xuelan Zhang,Jianfeng Shan 한국화학공학회 2022 Korean Journal of Chemical Engineering Vol.39 No.11

In the industrial production, water exists inevitably into feed stocks in the form of impurity, and it can produce a negative effect in the hydrogenation reaction due to the preferential adsorption of water on active sites. Here, the surfactants (polyvinylpyrrolidone, poloxamer, polyethylene glycol and hexadecyl trimethyl ammonium bromide) are used to improve physicochemical property of Cu/SiO2 catalysts, so that Cu/SiO2 catalysts had a good hydrogenation performance at condition containing water. The appropriate addition amount of surfactants in the catalyst preparation process effectively hindered the agglomeration of copper species by steric configuration and repulsion effect between Cu2+ and positive ionizable, which brought about high copper dispersion and small particle size. Meanwhile, the decomposition of surfactants produced many pores during calcination, resulting in the increased of specific surface area and average pore diameter. These advantages provided more chances for reactants to touch active sites due to spatial restriction and the increase of the number of active sites, so that the negative effects of water can be counteracted. The conversion of Cu/SiO2 catalysts, that the surfactants was added in the catalyst preparation process, increased 60% to 200% at reaction condition containing water.

Evaluation of the seismic performance of butt-fusion joint in large diameter polyethylene pipelines by full-scale shaking table test

Shi Jianfeng,Feng Ying,Tao Yangji,Guo Weican,Yao Riwu,Zheng Jinyang 한국원자력학회 2023 Nuclear Engineering and Technology Vol.55 No.9

High-density polyethylene (HDPE) pipelines in nuclear power plants (NPPs) have to meet high requirements for seismic performance. HDPE pipes have been proved to have good seismic performance, but joints are the weak links in the pipelines, and pipeline failures usually initiate from the defects inside the joints. Limited data are available on the seismic performance of butt-fusion joints of HDPE pipelines in NPPs, especially in terms of defects changes inside the joints after earthquakes. In this paper, full-scale shaking table tests were performed on a test section of suspended HDPE pipelines in an NPP, which included straight pipes, elbows, and 10 butt-fusion joints. During the tests, the seismic load-induced strain of the joints was analyzed by strain gauges, and it was much smaller than the internal pressure and self-weight-induced strain. Before and after the shaking table tests, phased array ultrasonic testing (PA-UT) was conducted to detect defects inside the joints. The locations, numbers, and dimensions of the defects were analyzed. It was found that defects were more likely to occur in elbows joints. No new defect was observed after the shaking table tests, and the defects showed no significant growth, indicating the satisfactory seismic performance of the butt-fusion joints.

Characteristics of Undular Surges Propagating in Still Water

Feidong Zheng,Pingyi Wang,Jianfeng An,Yun Li 대한토목학회 2021 KSCE JOURNAL OF CIVIL ENGINEERING Vol.25 No.9

In this study, physical experiments were performed in a horizontal rectangular channel to investigate the evolution of undular surges that propagate in still water and the reflection of these surges on a vertical wall. The generated undular surges were located in the intermediate water depth wave regime. The results demonstrated that the maximum wave steepness attained by undular surges was close to the breaking limit of progressive waves at intermediate water depths. Nevertheless, the dispersion relationship was inconsistent with the wave dispersion trend for intermediate gravity waves and strongly depended on the initial flow conditions and surge type. Furthermore, it was found that the longitudinal current velocity was governed primarily by water surface displacement. A novel and universal formula based on the experimental results was proposed to describe the velocity distributions in different types of undular surge flows. In addition, a non-breaking undular surge behaved as a solitary wave regarding its reflection on a vertical wall. Overall, the findings highlighted the effects of the initial flow conditions on the hydrodynamic characteristics of undular surges and demonstrated the unique features of undular surges that propagate in still water.

Finite element analysis of high-density polyethylene pipe in pipe gallery of nuclear power plants

Shi, Jianfeng,Hu, Anqi,Yu, Fa,Cui, Ying,Yang, Ruobing,Zheng, Jinyang Korean Nuclear Society 2021 Nuclear Engineering and Technology Vol.53 No.3

High density polyethylene (HDPE) pipe has many advantages over metallic pipe, and has been used in non-safety related application for years in some nuclear power plants (NPPs). Recently, HDPE pipe was introduced into safety related applications. The main difference between safety-related and non-safety-related pipes in NPPs is the design method of extra loadings such as gravity, temperature, and earthquake. In this paper, the mechanical behavior of HDPE pipe under various loads in pipe gallery was studied by finite element analysis (FEA). Stress concentrations were found at the fusion regions on inner surface of mitered elbows of HDPE pipe system. The effects of various factors were analyzed, and the influence of various loads on the damage of HDPE pipe system were evaluated. The results of this paper provide a reference for the design of nuclear safety-related Class 3 HDPE pipe. In addition, as the HDPE pipes analyzed in this paper were suspended in pipe gallery, it can also serve as a supplementary reference for current ASME standard on Class 3 HDPE pipe, which only covers the application for buried pipe application.

Fast-convergence trilinear decomposition algorithm for angle and range estimation in FDA-MIMO radar

Wang, Cheng,Zheng, Wang,Li, Jianfeng,Gong, Pan,Li, Zheng Electronics and Telecommunications Research Instit 2021 ETRI Journal Vol.43 No.1

A frequency diverse array (FDA) multiple-input multiple-output (MIMO) radar employs a small frequency increment across transmit elements to produce an angle-range-dependent beampattern for target angle and range detection. The joint angle and range estimation problem is a trilinear model. The traditional trilinear alternating least square (TALS) algorithm involves high computational load due to excessive iterations. We propose a fast-convergence trilinear decomposition (FC-TD) algorithm to jointly estimate FDA-MIMO radar target angle and range. We first use a propagator method to obtain coarse angle and range estimates in the data domain. Next, the coarse estimates are used as initialized parameters instead of the traditional TALS algorithm random initialization to reduce iterations and accelerate convergence. Finally, fine angle and range estimates are derived and automatically paired. Compared to the traditional TALS algorithm, the proposed FC-TD algorithm has lower computational complexity with no estimation performance degradation. Moreover, Cramer-Rao bounds are presented and simulation results are provided to validate the proposed FC-TD algorithm effectiveness.

Responsive manganese-based nanoplatform amplifying cGAS-STING activation for immunotherapy

Qingbin He,Runxiao Zheng,Junchi Ma,Luyang Zhao,Yafang Shi,Jianfeng Qiu 한국생체재료학회 2023 생체재료학회지 Vol.27 No.00

Background The activation of the cyclic guanosine monophosphate-adenosine monophosphate synthasestimulator of interferon genes (cGAS-STING) signaling pathway has attracted great attention for its ability to up-regulate innate immune response and thus enhance cancer immunotherapy. However, many STING agonists limit the further advancement of immunotherapy due to weak tumor responsiveness or low activation efficiency. The responsive and effective activation of cGAS-STING signaling in tumors is a highly challenging process. Methods In this study, a manganese-based nanoplatform (MPCZ NPs) was constructed that could responsively and efficiently generate more manganese ions (Mn2+) and reactive oxygen species (ROS) to activate cGAS-STING signaling pathway. Briefly, manganese dioxide (MnO2) was loaded with zinc protoporphyrin IX (ZPP) molecule and coated by polydopamine (PDA) embedded with NH4HCO3 to obtain MPCZ NPs. Additionally, MPCZ NPs were evaluated in vitro and in vivo for their antitumor effects by methyl thiazolyl tetrazolium (MTT) assay and TUNEL assays, respectively. Results In this system, tumor responsiveness was achieved by exogenous (laser irradiation) and endogenous (high levels GSH) stimulation, which triggered the collapse or degradation of PDA and MnO2. Moreover, the release of Mn2+ augmented the cGAS-STING signaling pathway and enhanced the conversion of hydrogen peroxide (H2O2) to hydroxyl radical (·OH) under NIR laser irradiation. Furthermore, the release of ZPP and the elimination of GSH by MPCZ NPs inhibited HO-1 activity and prevented ROS consumption, respectively. Conclusions This adopted open source and reduce expenditure strategy to effectively generate more ROS and Mn2+ to responsively activate cGAS-STING signaling pathway, providing a new strategy for improving immunotherapy.

Cloning of the Correct Full Length cDNA of NF-kB-repressing Factor

Yumin Mao,Dai Jianfeng,Jin Feng,Ji Chaoneng,Zheng Zhongshou,Gu Shaohua,Wu Qihan,Wang Liu,Yin Gang,Xie Yi 한국분자세포생물학회 2003 Molecules and cells Vol.16 No.3

Transcriptome analysis revealed regulatory mechanisms of light and culture density on free-living sporangial filaments of Neopyropia yezoensis (Rhodophyta)

Bangxiang He,Zhenbin Zheng,Jianfeng Niu,Xiujun Xie,Guangce Wang 한국조류학회I 2023 ALGAE Vol.38 No.4

Previous research indicated that free-living sporangial filament keep hollow morph under high-culture density and form bipartite cells under low-culture density, while the following conchospore release was inhibited by high light. Here, we further explored the molecular bases of these affects caused by light and culture density using a transcriptome analysis. Many differentially expressed genes (DEGs) related to carbon dioxide concentration and fixation, photosynthesis, chlorophyll synthesis and nitrogen absorption were upregulated under high-light conditions compared with low-light conditions, indicating the molecular basis of rapid vegetative growth under the former. The stress response- and ion transport-related DEGs, as well as the gene encoding the vacuole formation–brefeldin A-inhibited guanine nucleotide exchange protein (BIG, py05721), were highly expressed under high-density conditions, indicating the molecular basis of the hollow morph of free-living sporangial filaments under high-culture density conditions. Additionally, the brefeldin A treatment indicated that the hollow morph was directly influenced by vacuole formation-related vesicle traffic. Others DEGs related to cell wall components, zinc-finger proteins, ASPO1527, cell cycle and cytoskeleton were highly expressed in the low density with low-light group, which might be related to the formation and release of conchospores. These results provide a deeper understanding of sporangial filaments in Neopyropia yezoensis and related species.

A Novel Bio-inspired Trusted Routing Protocol for Mobile Wireless Sensor Networks

( Mingchuan Zhang ),( Changqiao Xu ),( Jianfeng Guan ),( Ruijuan Zheng ),( Qingtao Wu ),( Hongke Zhang ) 한국인터넷정보학회 2014 KSII Transactions on Internet and Information Syst Vol.8 No.1

Routing in mobile wireless sensor networks (MWSNs) is an extremely challenging issue due to the features of MWSNs. In this paper, we present a novel bio-inspired trusted routing protocol (B-iTRP) based on artificial immune system (AIS), ant colony optimization (ACO) and Physarum optimization (PO). For trust mechanism, B-iTRP monitors neighbors` behavior in real time and then assesses neighbors` trusts based on AIS. For routing strategy, each node proactively finds routes to the Sink based on ACO. When a backward ant is on the way to return source, it senses the energy residual and trust value of each node on the discovered route, and calculates the link trust and link energy of the route. Moreover, B-iTRP also assesses the availability of route based on PO to maintain the route table. Simulation results show how B-iTRP can achieve the effective performance compared to existing state-of-the-art algorithms.