Instability Prediction of Valve Motion and Internal Flow in Novel Large-scale Reciprocating Pump

Yi Ma,Yutao Chen,He Zhang,Huashuai Luo,Hongying Deng 한국유체기계학회 2019 International journal of fluid machinery and syste Vol.12 No.1

To study the transient valve motions and flow pulsation of novel five-cylinder double-acting reciprocating pump, the theoretical analysis and computational fluid dynamics (CFD) method are employed to investigate the full-cycle working process of the pump. The theoretical models describing the motions and flow rates of hydraulic end are established for reciprocating pump under the actions of piston and valves. The open-close behavior of suction and discharge valves, internal turbulent flow and pulsation characteristics of the pump are studied and the effects of crank speed on those are analyzed in detail. The results show that the valves of reciprocating pump open and close quickly and non-linearly with various degrees of striking velocities and lag phenomena. Through the time and frequency domain results of flow pulsation, the single-cavity frequency is the dominant frequency. The most obvious amplitude appears for discharge flow pulsation, which gradually increases with crank speed. The results could provide useful information for the optimization of reciprocating pumping systems.

Effects of ZrB2 Nanoparticles on the Microstructures and Tensile Properties of a Hot Extruded In Situ AA6111 Composite

Ran Tao,Yutao Zhao,Gang Chen,Xizhou Kai 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.12

Particle-reinforced aluminum matrix composites (PRAMCs) always show a low forming stability because the particles areeasily separated from the matrix, leaving voids and forming cracks. Extruded in situ PRAMCs are gradually replacing ex situPRAMCs due to the higher interface bonding between the in situ reinforcements and matrix. In this study, a hot-extrudedin situ AA6111 composite with ZrB2nanoparticles was obtained from an Al-Zr-B system. The effects of the ZrB2contenton the geometrically necessary dislocation (GND) density, grain size, grain boundaries, textures and tensile properties ofAA6111 composites were researched. The results showed that as the volume fraction of ZrB2increased, the mean GNDdislocation density increased from 1.53 × 1015m−2 to 3.23 × 1015m−2, and most dislocations were located around the ZrB2nanoparticle clusters. In addition, an increase in the ZrB2content decreased the frequency of high-angle grain boundaries(HAGBs) from 79.28 to 69.45% and increased the frequency of low-angle grain boundaries (LAGBs). ZrB2nanoparticleclusters which were located along the grain boundaries promoted continuous dynamic recrystallization (CDRX) and remarkablyrefined the grains, with the mean size decreasing from 48.2 to 1.8 μm. However, dispersed ZrB2nanoparticles inside thegrains suppressed CDRX. Tensile tests showed that the properties rose dramatically with an increasing volume fraction ofZrB2,and the optimum ultimate tensile strength (UTS), yield strength (YS) and elongation (El) of the 2 vol% ZrB2/AA6111composite were 365 MPa, 280 MPa, and 25.6%, respectively. The mechanisms for CDRX, strengthening and plasticityenhancement were determined and discussed.

A Behavior-based Adaptive Dynamic Programming Method for Multiple Mobile Manipulators Coordination Control

Zhenyi Zhang,Jianfei Chen,Zhibin Mo,Yutao Chen,Jie Huang 제어·로봇·시스템학회 2023 International Journal of Control, Automation, and Vol.21 No.9

In this work, a behavior-based adaptive dynamic programming (BADP) method is proposed for the coordination control of unmanned ground vehicle-manipulator systems (UGVMs). Through a null-space-based behavioral control (NSBC) framework, the multi-objective coordination control is transformed into a single-objective tracking control at the mission layer. Since cost functions and control constraints are simplified at the control layer, the complexity of controller design is reduced. Then, an identifier-actor-critic reinforcement learning algorithm framework is introduced to learn the optimal control policy by balancing the control performance and consumption. Simulation results show that control costs are reduced by around 13.5% per sampling period compared to existing multiple objective control methods. Finally, the BADP method is experimentally validated using four real UGVMs.

Ultrashort pulse laser processing of ZrO2 ceramics

Qibiao Yang,Yunhan You,Bojin Cheng,Lie Chen,Jian Cheng,Deyuan Lou,Yutao Wang,Dun Liu 한양대학교 청정에너지연구소 2023 Journal of Ceramic Processing Research Vol.24 No.2

It is crucial to investigate the mechanism of ultrashort pulse laser processing of ZrO2 ceramics to improve its processingaccuracy and efficiency. An ultrashort pulse laser was used to fabricate square grooves on the surface of ZrO2 ceramics. Thedepth, surface roughness, and surface topography of grooves were analyzed by the laser confocal microscope, optical profiler,and scanning electron microscope. The effects of different laser parameters on the material removal efficiency and processingquality of ZrO2 ceramics were studied. The results show that as the laser fluence increases, material removal efficiency firstincreases and then decreases, while the surface roughness first decreases and then increases. The heat accumulation effect issevere when using high repetition frequency, and the processed surface shows melt damage. As the pulse width increases from390fs to 6ps, the ablation threshold increases from 1.28 J/cm2 to 1.92 J/cm2. However, the material removal efficiency decreasesgradually. Furthermore, the material removal efficiency in burst mode significantly reduces due to the plasma shielding andredeposition of distinct granular deposits within the grooves. These findings can serve as a guide for controlling and optimizingthe process parameters of an ultrashort pulse laser processing of ZrO2 ceramics.

Purification process and reduction of heavy metals from industrial wastewater via synthesized nanoparticle for water supply in swimming/water sport

Leiming Fu,Junlong Li,Jianming Yang,Yutao Liu,Chunxia He,Yifei Chen Techno-Press 2023 Advances in nano research Vol.15 No.5

Heavy metals, widely present in the environment, have become significant pollutants due to their excessive use in industries and technology. Their non-degradable nature poses a persistent environmental problem, leading to potential acute or chronic poisoning from prolonged exposure. Recent research has focused on separating heavy metals, particularly from industrial and mining sources. Industries such as metal plating, mining operations, tanning, wood and chipboard production, industrial paint and textile manufacturing, as well as oil refining, are major contributors of heavy metals in water sources. Therefore, removing heavy metals from water is crucial, especially for safe water supply in swimming and water sports. Iron oxide nanoparticles have proven to be highly effective adsorbents for water contaminants, and efforts have been made to enhance their efficiency and absorption capabilities through surface modifications. Nanoparticles synthesized using plant extracts can effectively bind with heavy metal ions by modifying the nanoparticle surface with plant components, thereby increasing the efficiency of heavy metal removal. This study focuses on removing lead from industrial wastewater using environmentally friendly, cost-effective iron nanoparticles synthesized with Genovese basil extract. The synthesis of nanoparticles is confirmed through analysis using Transmission Electron Microscope (TEM) and X-ray diffraction, validating their spherical shape and nanometer-scale dimensions. The method used in this study has a low detection limit of 0.031 ppm for measuring lead concentration, making it suitable for ensuring water safety in swimming and water sports.

Synthesis of Direct β‐to‐β Linked Porphyrin Arrays with Large Electronic Interactions: Branched and Cyclic Oligomers

Cai, Hao,Fujimoto, Keisuke,Lim, Jong Min,Wang, Chaojie,Huang, Weiming,Rao, Yutao,Zhang, Senmiao,Shi, Hui,Yin, Bangshao,Chen, Bo,Ma, Ming,Song, Jianxin,Kim, Dongho,Osuka, Atsuhiro WILEY‐VCH Verlag 2014 Angewandte Chemie Vol.126 No.41

<P><B>Abstract</B></P><P>Direct β‐to‐β linked branched and cyclic porphyrin trimers and pentamers have been synthesized by the Suzuki–Miyaura coupling of β‐borylporphyrins and β‐bromoporphyrins. The cyclic porphyrin trimer, the smallest directly linked cyclic porphyrin wheel to date, and its twined pentamer, exhibit small electrochemical HOMO–LUMO gaps, broad nonsplit Soret bands, and red‐shifted Q‐bands, thus indicating large electronic interactions between the constituent porphyrin units.</P>

Yaw effects on train aerodynamics on a double-track viaduct: A wind tunnel study

Wenhui Li,Tanghong Liu,Pedro Martinez-Vazquez,Zhengwei Chen,Xiaoshuai Huo,Zijian Guo,Yutao Xia 한국풍공학회 2021 Wind and Structures, An International Journal (WAS Vol.33 No.3

The aerodynamic performance of a scaled high-speed train model mounted on a double-track viaduct was studied through a wind tunnel test. The pressure distribution of different loops and the centerline on the streamlined nose region, as well as the aerodynamic load coefficients of the leading car were explored under yaw effects ranging from β=-30° to β=30°. Results showed that Reynolds effects became independent when the wind speed surpassed 40 m/s, the corresponding Re of which equals 6.51 × 105 . The pressures recorded along the centerline of train nose for the upstream scenario, was more sensitive to the yaw effects as the largest pressure difference gradually broadened against yaw angles. In addition, the pressure coefficients along the centerline and symmetrical taps of the loops, approximately fit a quadratic relationship with respect to yaw angles. The presence of the tracks and viaduct decks somehow mitigated the intensity of the airflow at downstream side. The experimental test also revealed that, the upstream configuration provided higher mean side force, yawing, and rolling moments up to β=20° whereas over that angle the force and moments exhibited the opposite performance.