The Experts below are selected from a list of 213 Experts worldwide ranked by ideXlab platform
Jianyu Yuan - One of the best experts on this subject based on the ideXlab platform.
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Bubble Formation at a Submerged Orifice in High-Speed Horizontal Oscillation
Metallurgical and Materials Transactions B, 2016Co-Authors: Ningzhen Wang, Xiang Chen, Jianyu Yuan, Gui-quan Wang, Huawei Zhang, Yuan LiuAbstract:Reducing the cell size of aluminum foams is always a hot and difficult topic in the fabrication of aluminum foams by Gas Injection route. There lacks theoretical guidance for the bubble size reduction when foaming by the dynamic Gas Injection Method. For the convenience of observation, the aqueous bubbles from small-sized orifice in the high-speed horizontal oscillation were investigated in this paper. A bubble formation and detachment model in the high-speed horizontal oscillation system was proposed. The high-speed system with horizontal simple harmonic oscillation could reduce the average bubble size of aqueous foam effectively. The regularity of bubble formation and the influence of experimental parameters on average bubble size can be predicted by the theoretical model, and the experimental results agree well with the theoretical calculation. The results have shown that bubbles generally detach from the orifice at deceleration periods of the simple harmonic oscillation, and there exist several fixed sizes of bubbles with the fixed experimental parameters due to the effects of periodic forces. The average bubble size decreases with the increase of oscillation frequency and amplitude, and it roughly increases with the increase of Gas flow rate. Using the high-speed horizontal oscillation Method to prepare aluminum foams, the cell size can be reduced to about 1 mm. Moreover, the cell sizes of aluminum foam can be well predicted by this theoretical model.
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Study on quasi-static compressive properties of aluminum foam-epoxy resin composite structures
Composites Part B: Engineering, 2015Co-Authors: Jianyu Yuan, Xiang Chen, Wenwu ZhouAbstract:Closed cell aluminum foam (AF) has extensive application prospects due to its extended plateau stress region and high energy absorption capacity. As one of the most important manufacturing routes for aluminum foams, the Gas Injection Method still does not guarantee an excellent energy absorption performance. In order to improve the energy absorption capacity while remaining the plateau region extended, epoxy resin (ER) was infiltrated into the aluminum foams in various composite forms. In this paper, different AF-ER composite structures were designed and their uniaxial quasi-static compressive behaviors were investigated. The experimental results indicate that the plateau stress and energy absorption capability of the AF-ER composite structures increase with increasing amount of epoxy resin. Additionally, both the stress fluctuation and the peak stress in the plateau region become insignificant, which is beneficial for energy absorption applications. The composite form is also confirmed to have great effect on the compressive property of the AF-ER composite structures. At last, the Young's modulus of the composite structure is theoretically deduced while the plateau stress and the energy absorption capacity are fitted with the composite parameters by considering the contribution of aluminum foam, epoxy resin and the reciprocity of these two materials. The present model is found to have good agreement with experimental data.
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Effects of cell wall property on compressive performance of aluminum foams
Transactions of Nonferrous Metals Society of China, 2015Co-Authors: Jianyu YuanAbstract:Abstract The effects of cell wall property on the compressive performance of high porosity, closed-cell aluminum foams prepared by Gas Injection Method were investigated. The research was conducted both experimentally and numerically. Foam specimens prepared from conditioned melt were tested under uniaxial compressive loading condition. The cell wall microstructure and fracture were observed through optical microscope (OM) and scanning electron microscope (SEM), which indicates that the cell wall property is impaired by the defects in cell walls and oxide films on the cell wall surface. Subsequently, finite element (FE) models based on three-dimensional thin shell Kelvin tetrakaidecahedron were developed based on the mechanical properties of the raw material and solid material that are determined by using experimental measurements. The simulation results show that the plateau stress of the nominal stress–strain curve exhibits a linear relationship with the yield strength of the cell wall material. The simulation plateau stress is higher than the experimental data, partly owing to the substitution of solid material for cell wall material in the process of the establishment of FE models.
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Effect of orifice geometry on bubble formation in melt Gas Injection to prepare aluminum foams
Science China Technological Sciences, 2014Co-Authors: Jianyu YuanAbstract:The bubble formation process at submerged orifices with different geometry is investigated in the preparation of aluminum foams by Gas Injection Method. The bubble profile on a horizontal plate is calculated by quasi-static analysis through Laplace equation. The bubble formation process is then distinguished into three stages: nucleation stage, growth stage and detachment stage in wetting and less wetting conditions based on the force balance analysis. In addition, the bubble size at high Reynolds number is obtained by considering the contribution of buoyancy, pressure force, inertial force, drag force and surface tension based on the three stages of bubble formation. The bubble size is confirmed to be sensitive to the equivalent contact angle, which consists of two terms including the contact angle and the wedge angle. Therefore, the wedge angle is introduced in the design of Gas outlet orifices for the purpose of decreasing bubble size generated. The experimental study is conducted at three different types of stainless steel orifices under constant Gas flow rates (0.05–2 L/min). It is clarified that the orifice geometry and the orifice size are both responsible for the cell size of aluminum foams. The experimental results for three different types of orifices show a consistent trend with the theoretical predictions at various Gas flow rates. In the design of orifices to generate small bubbles in the melt, the wedge angle that coordinates with the contact angle is thus suggested.
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Effect of contact angle on bubble formation at submerged orifices
Journal of Materials Science, 2014Co-Authors: Jianyu Yuan, Yutong ZhouAbstract:This paper presents a theoretical model and experimental results of the generation of bubbles due to the Injection of a constant flow rate of Gas through an orifice submerged in liquid. The bubble formation process can be identified into three distinct stages termed (1) nucleation stage, (2) growth stage, and (3) detachment stage by analyzing the evolution of interface equilibrium and force balance conditions. Influence of contact angle on bubble formation at each stage is quantitatively elucidated. Experimental investigations in the preparation process of aluminum foams by Gas Injection Method were conducted, and the generated bubble size was measured. The theoretical prediction of the present model suits well with the experimental results when a contact angle of 30° is introduced. The present model covers a wide range of contact angle (θ < 90°) at different Gas flow rates and orifice radii in both aqueous and metallic systems.
Da-wei Liu - One of the best experts on this subject based on the ideXlab platform.
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Placement of a Jejunal Feeding Tube via an Ultrasound-Guided Antral Progressive Water Injection Method.
Chinese medical journal, 2018Co-Authors: Qing Zhang, Jian-hua Sun, Jia-tao Liu, Xiao-ting Wang, Da-wei LiuAbstract:Background: Jejunal feeding tube allows the nutrition of critical care patients more easy and safe. However, its placement remains a challenge. This study aimed to introduce a jejunal feeding tube through an ultrasound-guided antral progressive water Injection Method and subsequently to examine its efficacy. Methods: Between April 2016 and April 2017, 54 patients hospitalized in the Department of Critical Care Medicine, Peking Union Medical College Hospital, China who needed nutritional support through a jejunal feeding tube were recruited for this study. Patients who applied ultrasound-guided antral progressive water Injection Method were classified into the experimental group. Patients who applied conventional Method were registered as control group. Results: No significant differences were found in age, body mass index, and Acute Physiology and Chronic Health Evaluation score, but a significant difference in operation time was found between the experimental group and the control group. Of the 24 individuals in the control group, 17 displayed clear catheter sound shadows once the tube entered the esophagus. In comparison, of the 30 individuals in the experimental group, all harbored catheter sound shadows through the esophageal Gas Injection Method. Subsequent observation revealed that in the control group (via ultrasonographic observation), 15 individuals underwent successful antral tube entry, for a success rate of 63%. In the experimental group (via antral progressive water Injection), 27 individuals underwent successful antral tube entry, for a success rate of 90%. There was a significant difference between the success rates of the two groups (χ2 = 5.834, P = 0.022). Conclusion: The antral progressive water Injection Method for the placement of a jejunal feeding tube is more effective than the traditional ultrasonic placement Method. Key words: Jejunal Feeding Tube; Nutritional Support; Ultrasound-Guided Antral Progressive Water Injection Method
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Placement of a Jejunal Feeding Tube via an Ultrasound-Guided Antral Progressive Water Injection Method
Wolters Kluwer, 2018Co-Authors: Qing Zhang, Jian-hua Sun, Jia-tao Liu, Xiao-ting Wang, Da-wei LiuAbstract:Background: Jejunal feeding tube allows the nutrition of critical care patients more easy and safe. However, its placement remains a challenge. This study aimed to introduce a jejunal feeding tube through an ultrasound-guided antral progressive water Injection Method and subsequently to examine its efficacy. Methods: Between April 2016 and April 2017, 54 patients hospitalized in the Department of Critical Care Medicine, Peking Union Medical College Hospital, China who needed nutritional support through a jejunal feeding tube were recruited for this study. Patients who applied ultrasound-guided antral progressive water Injection Method were classified into the experimental group. Patients who applied conventional Method were registered as control group. Results: No significant differences were found in age, body mass index, and Acute Physiology and Chronic Health Evaluation score, but a significant difference in operation time was found between the experimental group and the control group. Of the 24 individuals in the control group, 17 displayed clear catheter sound shadows once the tube entered the esophagus. In comparison, of the 30 individuals in the experimental group, all harbored catheter sound shadows through the esophageal Gas Injection Method. Subsequent observation revealed that in the control group (via ultrasonographic observation), 15 individuals underwent successful antral tube entry, for a success rate of 63%. In the experimental group (via antral progressive water Injection), 27 individuals underwent successful antral tube entry, for a success rate of 90%. There was a significant difference between the success rates of the two groups (χ2 = 5.834, P = 0.022). Conclusion: The antral progressive water Injection Method for the placement of a jejunal feeding tube is more effective than the traditional ultrasonic placement Method
D.m. Nguyen - One of the best experts on this subject based on the ideXlab platform.
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Test Plan for Measuring Ventilation Rates and Combustible Gas Levels in TWRS Active Catch Tanks
2000Co-Authors: D.m. NguyenAbstract:The purpose of this data collection activity is to obtain data for a screening of combustible Gases in catch tanks that are currently operated by the River Protection Project (RPP). The results will be used to support closure of the flammable Gas unreviewed safety question for these facilities. The data collection will be conducted in accordance with the ''Tank Safety Screening Data Quality Objective'' (Dukelow et al. 1995). Combustible Gas, ammonia, and organic vapor levels in the headspace of the catch tanks will be field-measured using hand-held instruments. If a combustible Gas level measurement in a tank exceeds an established threshold, vapor grab samples (i.e., Hoke and SUMMA) will be collected for laboratory analysis. In addition, ventilation rates of some catch tanks will be determine using the tracer Gas Injection Method to evaluate removal of flammable Gas by air flowing through the tanks. This test plan identifies the field tests, sample collection, laboratory analysis, quality assurance, and reporting objectives for this data collection effort. The plan also provides step-by-step direction for field measurement of combustible Gas concentrations and determination of ventilation rates.
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Test Plan for Measuring Ventilation Rates and Combustible Gas Levels in TWRS Active Catch Tanks
2000Co-Authors: D.m. NguyenAbstract:The purpose of this data collection activity is to obtain data for a screening of combustible Gases in catch tanks that are currently operated by the River Protection Project (RPP). The results will be used to support closure of the flammable Gas unreviewed safety question for these facilities. The data collection will be conducted in accordance with the ''Tank Safety Screening Data Quality Objective'' (Dukelow et a1 1995). Combustible Gas, ammonia, and organic vapor levels in the headspace of the catch tanks will be field-measured using hand-held instruments. If a combustible Gas level measurement in a tank exceeds an established threshold, vapor grab samples will be collected for laboratory analysis. In addition, ventilation rates of some catch tanks will be determined using the tracer Gas Injection Method to evaluate removal of flammable Gas by air flowing through the tanks. This test plan identifies the field tests, sample collection, laboratory analysis, quality assurance, and reporting objectives for this data collection effort. The plan also provides step by-step direction for field measurement of combustible Gas concentrations and determination of ventilation rates.
Saied Taghiramezani - One of the best experts on this subject based on the ideXlab platform.
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effect of hydrogen and argon shrouding Gas flow rate on high temperature oxidation behavior of nicraly coating by solid shielding shrouded plasma spray ssps
Surface & Coatings Technology, 2020Co-Authors: Reza Saharkhiz, Zia Valefi, Masoud Mirjani, Alireza Abdollahi, Saied TaghiramezaniAbstract:Abstract This paper investigates the effect of hydrogen and argon shrouding Gas flow rates in solid shielding shrouded plasma spray (SSPS) Method on in-flight oxidation, formation and growth of the TGO layer and high-temperature oxidation behavior of NiCrAlY coating. With this in mind, NiCrAlY coating was applied on the Hastelloy X substrate by solid shielding shrouded plasma spray (SSPS) and compared with the conventional atmospheric plasma spray (APS). High-temperature oxidation was carried out at 1000 °C for 200 h. Microstructure of the coatings before and after oxidation was evaluated by scanning electron microscope (SEM) equipped with energy dispersive spectrometer (EDS). To study the effect of solid shielding shrouded plasma spray on the properties of metallic coatings, the variable parameters such as the shroud Gas nature (Ar, H2), the Gas Injection Method (internal, external or both) and their flow rates, were examined. The results indicated the better operation of the coatings deposited under the protection of internal argon shroud Gas with a flow rate of 75SLPM, which could be due to better protection of the metallic particles against in-flight oxidation. This sample represented the lowest thickness of the TGO layer (2.25 μm). The formation and growth of the TGO layer were higher in APS coating (3.82 μm) than that of SSPS. Consequently, this can prove by the preservation of mono-layered TGO of SSPS coating even after 200 h oxidation without the formation of any CSN clusters.
Xiang Chen - One of the best experts on this subject based on the ideXlab platform.
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Compressive performance and deformation mechanism of the dynamic Gas Injection aluminum foams
Materials Characterization, 2019Co-Authors: Ningzhen Wang, Eric Maire, Xiang Chen, Jérôme Adrien, Yasin Amani, Ying ChengAbstract:The dynamic Gas Injection Method with high-speed horizontal oscillation could reduce the cell size and improve the cell quality of aluminum foams, so it is of interest to study the compressive performance and deformation mechanism of the foams produced with this process. In-situ compression in X-ray tomography was used for this research. Results have shown that the plateau stresses of bulk aluminum foams prepared by the dynamic Gas Injection Method are in the range of 0.3 ~ 11 MPa. When the cell size is reduced to around 1 mm, the plateau stress could reach 22 MPa. In addition, the brittle deformation characteristics of aluminum foams in the quasi-static compression process are obvious. The dynamic Gas Injection Method could greatly improve the mechanical properties of aluminum foams, and aluminum foams prepared by this Method have a better compressive performance compared to that prepared by static Method even at the same relative density. The uniformity of the cell size and sphericity also affects the mechanical properties. The result of in-situ compression shows that there are two main failure modes for cell walls of aluminum foams: the fracture after buckles of the cell walls and the direct fracture of the cell walls. The aluminum foams prepared by the dynamic Gas Injection Method could have a wide application prospect due to its superior compressive performance.
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Compressive performance and deformation mechanism of the dynamic Gas Injection aluminum foams
Materials Characterization, 2019Co-Authors: Ningzhen Wang, Eric Maire, Xiang Chen, Jérôme Adrien, Yasin Amani, Ying ChengAbstract:Abstract The dynamic Gas Injection Method with high-speed horizontal oscillation could reduce the cell size and improve the cell quality of aluminum foams, so it is of interest to study the compressive performance and deformation mechanism of the foams produced with this process. In-situ compression in X-ray tomography was used for this research. Results have shown that the plateau stresses of bulk aluminum foams prepared by the dynamic Gas Injection Method are in the range of 0.3–11 MPa. When the cell size is reduced to around 1 mm, the plateau stress could reach 22 MPa. In addition, the brittle deformation characteristics of the aluminum foams in the quasi-static compression process are obvious. The dynamic Gas Injection Method could greatly improve the mechanical properties of aluminum foams, and aluminum foams prepared by this Method have a better compressive performance compared to that prepared by static Method even with the same relative density. The uniformities of the cell size and sphericity also affect the mechanical properties. The result of in-situ compression shows that there are two main failure modes for cell walls of aluminum foams: the fracture after buckles of the cell walls and the direct fracture of the cell walls. The aluminum foams prepared by the dynamic Gas Injection Method could have a wide application prospect due to its superior compressive performance.
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Bubble Formation at a Submerged Orifice in High-Speed Horizontal Oscillation
Metallurgical and Materials Transactions B, 2016Co-Authors: Ningzhen Wang, Xiang Chen, Jianyu Yuan, Gui-quan Wang, Huawei Zhang, Yuan LiuAbstract:Reducing the cell size of aluminum foams is always a hot and difficult topic in the fabrication of aluminum foams by Gas Injection route. There lacks theoretical guidance for the bubble size reduction when foaming by the dynamic Gas Injection Method. For the convenience of observation, the aqueous bubbles from small-sized orifice in the high-speed horizontal oscillation were investigated in this paper. A bubble formation and detachment model in the high-speed horizontal oscillation system was proposed. The high-speed system with horizontal simple harmonic oscillation could reduce the average bubble size of aqueous foam effectively. The regularity of bubble formation and the influence of experimental parameters on average bubble size can be predicted by the theoretical model, and the experimental results agree well with the theoretical calculation. The results have shown that bubbles generally detach from the orifice at deceleration periods of the simple harmonic oscillation, and there exist several fixed sizes of bubbles with the fixed experimental parameters due to the effects of periodic forces. The average bubble size decreases with the increase of oscillation frequency and amplitude, and it roughly increases with the increase of Gas flow rate. Using the high-speed horizontal oscillation Method to prepare aluminum foams, the cell size can be reduced to about 1 mm. Moreover, the cell sizes of aluminum foam can be well predicted by this theoretical model.
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Study on quasi-static compressive properties of aluminum foam-epoxy resin composite structures
Composites Part B: Engineering, 2015Co-Authors: Jianyu Yuan, Xiang Chen, Wenwu ZhouAbstract:Closed cell aluminum foam (AF) has extensive application prospects due to its extended plateau stress region and high energy absorption capacity. As one of the most important manufacturing routes for aluminum foams, the Gas Injection Method still does not guarantee an excellent energy absorption performance. In order to improve the energy absorption capacity while remaining the plateau region extended, epoxy resin (ER) was infiltrated into the aluminum foams in various composite forms. In this paper, different AF-ER composite structures were designed and their uniaxial quasi-static compressive behaviors were investigated. The experimental results indicate that the plateau stress and energy absorption capability of the AF-ER composite structures increase with increasing amount of epoxy resin. Additionally, both the stress fluctuation and the peak stress in the plateau region become insignificant, which is beneficial for energy absorption applications. The composite form is also confirmed to have great effect on the compressive property of the AF-ER composite structures. At last, the Young's modulus of the composite structure is theoretically deduced while the plateau stress and the energy absorption capacity are fitted with the composite parameters by considering the contribution of aluminum foam, epoxy resin and the reciprocity of these two materials. The present model is found to have good agreement with experimental data.
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Bubble Formation at a Submerged Orifice for Aluminum Foams Produced by Gas Injection Method
Metallurgical and Materials Transactions A, 2012Co-Authors: Xue Liu Fan, Xiang Chen, Xingnan Liu, Huiming ZhangAbstract:The bubble formation at a submerged orifice in the process of aluminum foams produced by Gas Injection Method is investigated. The experimental results show that the increase of the Gas flow rate and the orifice diameter can lead to increasing of the bubble size. The large orifice can make the frequency of bubble formation decrease by slowing down the increase of the Gas chamber pressure when the Gas flow rate increases. The effect of the Gas chamber volume on the bubble size can be ignored in the experiment when it expands from 1 to 125 cm3. A theoretical model of bubble formation, expansion, and detachment under constant flow conditions is established to predict the bubble size. The theoretical predictions for air-aluminum melt systems are consistent with the experimental results.
