Coatings are widely used to protect substrates in extreme thermal environments(e.g., arc heaters), and thermal shock resistance is a crucial parameter for the coatings, which requires tight interlayer bonding between ...Coatings are widely used to protect substrates in extreme thermal environments(e.g., arc heaters), and thermal shock resistance is a crucial parameter for the coatings, which requires tight interlayer bonding between coatings and substrates. In this work, Ni Cr Al Y coatings were highly required for the pure copper substrate to restrict the electric arc in arc heaters. To overcome the bonding difculty of coating on the copper surface, the Ni Cr Al Y coatings were prepared by two laser cladding methods: conventional laser cladding(CLC) and high-speed laser cladding(HSLC). The microstructure, composition, and thermal shock resistance of Ni Cr Al Y cladding layers prepared by both methods were investigated. Benefitting from the high cooling rate and high energy density, the HSLC-layer has better composition uniformity and tighter interlayer bonding than the CLC-layer, achieving a 30%–45% improvement in thermal cycling lifetime. Besides, the Ni Cr Al Y layers prepared on copper substrate by both laser cladding methods exhibit3–10 times better thermal shock resistance than those Ni Cr Al Y layers prepared by conventional spraying methods. It further confirms the great effects of metallurgical bonding and composition uniformity on the thermal shock resistance of coatings. The Ni Cr Al Y layers fail in the form of internal cracking and interface peeling, and the corresponding failure mechanism is discussed.展开更多
Directly grasping the tightly stacked objects may cause collisions and result in failures,degenerating the functionality of robotic arms.Inspired by the observation that first pushing objects to a state of mutual sepa...Directly grasping the tightly stacked objects may cause collisions and result in failures,degenerating the functionality of robotic arms.Inspired by the observation that first pushing objects to a state of mutual separation and then grasping them individually can effectively increase the success rate,we devise a novel deep Q-learning framework to achieve collaborative pushing and grasping.Specifically,an efficient non-maximum suppression policy(PolicyNMS)is proposed to dynamically evaluate pushing and grasping actions by enforcing a suppression constraint on unreasonable actions.Moreover,a novel data-driven pushing reward network called PR-Net is designed to effectively assess the degree of separation or aggregation between objects.To benchmark the proposed method,we establish a dataset containing common household items dataset(CHID)in both simulation and real scenarios.Although trained using simulation data only,experiment results validate that our method generalizes well to real scenarios and achieves a 97%grasp success rate at a fast speed for object separation in the real-world environment.展开更多
Objective ：To elucidate whether cell multiplication, apoptosis, glucose intake and p-Akt protein expression of bone Mesenchyreal Stem Cells（MSCs） of rats is influenced by a hypoxic environment ex vivo. Methods ：Pa...Objective ：To elucidate whether cell multiplication, apoptosis, glucose intake and p-Akt protein expression of bone Mesenchyreal Stem Cells（MSCs） of rats is influenced by a hypoxic environment ex vivo. Methods ：Passage 3 of bone marrow MSCs taken from Wistar rats,were cultured in a culturing chamber with 94%N2,1%O2,5%CO2 at 37℃. At different hypoxia time points ,0,0.5, 1,4 and 8 h, glucose uptake was assayed by using radiation isotope ^3H-G, Apoptotic Rate（AR） and dead rate（DR） were analyzed by flow cytometry（FCM） after Annexin V/PI staining, cell multiplication（by MTr methods） and p-Akt protein by immunocytochemistry and western blot. Results ：Assay for CD29^± ,CD44^± ,CD71^± ,CD34^-, Tn T^±（after 5-azacytidine agent inducing） and ALP^±（after bone differentiation agent inducing） suggested these bone-derived cells were MSCs. The ^3H-G intaking ratio （CPM/ flask value：157 ± 11,110 ± 11,107 ± 13,103 ± 10,100 ± 9 and 98 ± 10） of MSCs at different hypoxia time points, significantly decreased compared to that of normoxia（P 〈 0.01） and tended to descend slowly with hypoxia time duration, for which there was no statistical significance（P 〉 0.05）. The AR（0.09 ± 2.03%,12.9 ± 1.72%,13.7 ± 2.26%,13.8 ± 3.01%,14.1 ± 2.78% and 14.7 ± 4.01% at 0,0.5,1,4 and 8 h,respectively,P 〈 0.01） and DR （0.04, ± 1.79% ,0.93 ± 1.85% ,3.11 ± 2.14% ,4.09 ± 2.36% ,4.72 ± 2.05% and 4.91 ± 3.72% at 0,0.5,1,4 and 8 h, respectively, P 〈 0.05） at different hypoxia time points significantly increased compared to those time in normoxia; The AR further went up with time （P 〈 0.05）, however there was no statistical significance （P 〉 0.05） for the DR. Optical absorption value of MTr methods at different hypoxia time points significantly decreased compared to those with a corresponding normoxia time （P 〈 0.01） and degraded with time （in an hypoxic environment -P 〈 0.01）. IOD of p-Akt protein of MSCs at different hypoxia time points significantly increased （0.367 ± 0.031,0.556 ± 0.023,0.579 ± 0.013, 0.660 ± 0.024, 0.685 ± 0.039 and 0.685 ± 0.011, respectively） compared to their equivalents in normoxia （P〈0.05）, however, there was no statistical significance （P 〉 0.05） for different hypoxia time points. Hypoxia may result in ultramicrostructure changes, such as defluvium of Microvilli, apoptotic body, ＂margination＂ and so on and are further aggravated with hypoxia time stretching. Conclusion： Hypoxia may lead to a depression of MSCs intaldng glucose, creep of cell multiplication, upregulation of p-Akt protein and apoptosis of MSCs ex vivo.展开更多
The interaction between the metal and the support of supported metal catalysts, which are widely used in industry, is the primary focus of the study of such catalysts. With the developing understanding of the metal–s...The interaction between the metal and the support of supported metal catalysts, which are widely used in industry, is the primary focus of the study of such catalysts. With the developing understanding of the metal–support interaction, the intrinsic factor that influences the catalytic performance has been determined to be the structure of interfacial sites. Layered double hydroxides(LDHs, a class of two-dimensional layered anion clay) possess several unique characteristics, such as the following:(1) tunable elemental component, homogeneous distribution of metal cations.(2) anchoring eff ect.(3) multiple layered structure for exfoliation or intercalation and special memory eff ect;and(4) internal/external confinement eff ects during topological transformation. Taking LDHs and their derivatives as precursors or supports shows superior advantages in designing interfacial active catalysts with tunable properties. Therefore, this review is mainly focused on constructing interfacial active catalysts by LDHs and revealing the interfacial eff ects(including electronic, geometric, and bifunctional eff ects) on the catalytic performance that will provide new perspectives and approaches for the development of heterogeneous catalysis.展开更多
This paper proposes a deformation evolution and perceptual prediction methodology for additive manufacturing of lightweight composite driven by hybrid digital twins(HDT).In order to improve manufacturing quality of ir...This paper proposes a deformation evolution and perceptual prediction methodology for additive manufacturing of lightweight composite driven by hybrid digital twins(HDT).In order to improve manufacturing quality of irregular lightweight composite through boosting conceptual design in aeronautic and aerospace engineering,the HDT meaning hybridization of physical and digital domains,including deformation and energy efficiency can be built,where the essential parameters can be perceptually predicted in advance,by virtue of the fusion of physical sensors and digital information.The long short term memory(LSTM)can be employed to void vanishing gradient problem and improve predicting precision via Recurrent Neural Networks,thereby laying a foundation for the HDT.The diverse manufacturing requirements of different regions are integrated into the parameters designing phase by attaching region weights confirmed via empiricism and in-service simulation.The effects of slicing strategy and external support structures on manufacturing quality are considered from the perspective of improving dimensional accuracy.The manufacturing efficiency and comprehensive costs are accounted as consideration factors,which are perceptually predicted via LSTM.The designed manufacturing parameters through HDT were virtually examined by evaluating the deformation and equivalent stress distributions of fabricated lightweight component with composite material through AM process simulation.The physical experiments were conducted to verify the HDT-based pre-designing and optimization method of manufacturing parameters via fused deposition modeling(FDM).The energy consumption of actual manufacturing process was measured via digital power meter and applied to evaluate accuracy of perceptual prediction outcomes.The dimensional accuracy and distortion distribution of the manufactured lightweight prototype made with composite material were measured through the coordinate measuring machine(CMM)and 3D optical scanner.The proposed method demonstrates effectiveness in improving manufacturing quality and accurately predicting energy consumption,which have been verified with a three-way solenoid valve element,in which the maximum deformation was reduced by 39.78%and the mean absolute percentage error for perceptual prediction was 3.76%.展开更多
Taking half-tube part with curvature as an example,the Impact Hydroforming(IHF)characteristics were studied by combining the actual forming experiment and numerical simulation.The IHF experiment showed that wrinkles a...Taking half-tube part with curvature as an example,the Impact Hydroforming(IHF)characteristics were studied by combining the actual forming experiment and numerical simulation.The IHF experiment showed that wrinkles appeared at the bottom of the part during single-step forming,but no wrinkles were observed during double-step forming.The thinning rate and deviation of the wall thickness of the part in each area were less than 20%and 2.7 mm,correspondingly,and the drawing depth of the part reached 45.8 mm.The effect of double-step forming was better than that of single-step forming,which was related to the IHF forming law.Besides,the characteristics of the IHF process were studied by numerical simulation.The results indicated that when double-step forming was utilized,there was almost no velocity field in the opposite direction of deformation after the bottom of the part contacted the die,and the existence of stress state at the bottom would restrain and eliminate the wrinkles.The inertia effect evolved with the driving pressure.Specially,the inertia effect can improve the flow of metal and reduce the deviation of the wall thickness of the part under double-step forming.展开更多
CO_(2)capture and utilization(CCU)are two important processes to address the gigaton challenges in reducing greenhouse gas emissions.Given that both processes are energy-intensive,integrating CO_(2)capture and utiliza...CO_(2)capture and utilization(CCU)are two important processes to address the gigaton challenges in reducing greenhouse gas emissions.Given that both processes are energy-intensive,integrating CO_(2)capture and utilization(ICCU)can improve energy efficiency and reduce economic costs by eliminating steps such as CO_(2)concentration,storage,or capture media regeneration.Aiming at building a bridge between theoretical research and practical application,this review promotes the understanding of high-temperature ICCU,mild/low-temperature ICCU,and emerging electro-/photo-driven ICCU.The reaction mechanism and technical bottleneck are comprehensively evaluated,which could provide a perspective on the design principle of dualfunctional materials(DFMs)combining synergetic adsorptive and catalytic sites.On this basis,novel strategies are proposed from the viewpoint of chemical process intensification to strive for a thermodynamics and kinetics matching between the capture and in situ conversion processes.It is expected that this review can stimulate more research in the future involving expanding the product range,fabricating long-term DFMs,developing a workable reactor,optimizing operation conditions,and establishing an industrial demonstration.展开更多
In the application of long series batteries,there is always the phenomenon that multiple cells in a pack are unbalanced simultaneously.In view of this situation,a modevarying cell equalizer topology based on interleav...In the application of long series batteries,there is always the phenomenon that multiple cells in a pack are unbalanced simultaneously.In view of this situation,a modevarying cell equalizer topology based on interleaved parallel multiple transformers is proposed in this paper.Every unit in this equalizer can freely switch between LLC resonance mode and 3-state LC quasi-resonance mode.The boosting effect of LLC structure is used to reduce the number of transformer’s total turns.When multiple equalizer units need to work in LLC mode simultaneously,interleaved parallel technology is used to limit secondary side equalization current ripple for long-term protection of battery life.A prototype was designed and built to validate the effect of a closed loop LLC mode control algorithm with a state-of-charge(SOC)based equalization scheme selection strategy.Experimental results including up to 88.52%efficiency in LLC mode with 90.7%efficiency in 3-state LC mode,and minute level balancing time show the proposed topology demonstrates excellent balancing performance.展开更多
Qualitatively identifying the dominant catalytic site for each step of a semi-continuous reaction and semi-quantitatively correlating such different sites to the catalytic performance is of great significance toward t...Qualitatively identifying the dominant catalytic site for each step of a semi-continuous reaction and semi-quantitatively correlating such different sites to the catalytic performance is of great significance toward the integration of multiple well-optimized sites on a heterogeneous catalyst.Herein,a series of structurally defined TiO_(x)-based catalysts were synthesized to provide a feasible approach to investigate the aforementioned issues using the semi-continuous oxidation of glycerol as a model reaction.Detailed investigations have verified the simultaneous presence of two kinds of Pt active sites:1)Negatively charged Pt bound to the oxygen vacancies of modified TiO_(x)in the form of Pt^(δ−)-O_(v)-Ti^(3+) sites and 2)metallic Pt(Pt_(0)site)located away from the inter-face.Meanwhile,the proportion of surficial and interfacial sites varies over this series of catalysts.Combined in situ FTIR experiments revealed that the reaction network was well-tuned via a site cooperation mechanism:The surficial Pt_(0)sites dissociatively adsorb the OH group of glycerol with a monodentate bonding geometry and the Pt^(δ−)-O_(v)-Ti^(3+) sites dissociate the C=O bond of the aldehyde group in a bidentate form.Furthermore,CO-FTIR spectroscopy confirmed a correlation between the reaction rate/product selectivity and the fraction of surficial/interfacial sites.A rational proportion of surficial and interfacial sites is key to enabling a high yield of glyceric acid.The most active catalyst with 32%surface sites and 68%interfacial sites exhibited 90.0%glycerol conversion and 68.5%GLYA selectivity.These findings provide a deeper understanding of the structure-activity relationships using qualitative identification and semi-quantitative analysis.展开更多
基金supported by the National Key R&D Program of China (No.2021YFB2500600)the National Natural Science Foundation of China (No.11725210)。
文摘Coatings are widely used to protect substrates in extreme thermal environments(e.g., arc heaters), and thermal shock resistance is a crucial parameter for the coatings, which requires tight interlayer bonding between coatings and substrates. In this work, Ni Cr Al Y coatings were highly required for the pure copper substrate to restrict the electric arc in arc heaters. To overcome the bonding difculty of coating on the copper surface, the Ni Cr Al Y coatings were prepared by two laser cladding methods: conventional laser cladding(CLC) and high-speed laser cladding(HSLC). The microstructure, composition, and thermal shock resistance of Ni Cr Al Y cladding layers prepared by both methods were investigated. Benefitting from the high cooling rate and high energy density, the HSLC-layer has better composition uniformity and tighter interlayer bonding than the CLC-layer, achieving a 30%–45% improvement in thermal cycling lifetime. Besides, the Ni Cr Al Y layers prepared on copper substrate by both laser cladding methods exhibit3–10 times better thermal shock resistance than those Ni Cr Al Y layers prepared by conventional spraying methods. It further confirms the great effects of metallurgical bonding and composition uniformity on the thermal shock resistance of coatings. The Ni Cr Al Y layers fail in the form of internal cracking and interface peeling, and the corresponding failure mechanism is discussed.
基金This work was supported by the National Natural Science Foundation of China(61873077,61806062)Zhejiang Provincial Major Research and Development Project of China(2020C01110)Zhejiang Provincial Key Laboratory of Equipment Electronics.
文摘Directly grasping the tightly stacked objects may cause collisions and result in failures,degenerating the functionality of robotic arms.Inspired by the observation that first pushing objects to a state of mutual separation and then grasping them individually can effectively increase the success rate,we devise a novel deep Q-learning framework to achieve collaborative pushing and grasping.Specifically,an efficient non-maximum suppression policy(PolicyNMS)is proposed to dynamically evaluate pushing and grasping actions by enforcing a suppression constraint on unreasonable actions.Moreover,a novel data-driven pushing reward network called PR-Net is designed to effectively assess the degree of separation or aggregation between objects.To benchmark the proposed method,we establish a dataset containing common household items dataset(CHID)in both simulation and real scenarios.Although trained using simulation data only,experiment results validate that our method generalizes well to real scenarios and achieves a 97%grasp success rate at a fast speed for object separation in the real-world environment.
文摘Objective ：To elucidate whether cell multiplication, apoptosis, glucose intake and p-Akt protein expression of bone Mesenchyreal Stem Cells（MSCs） of rats is influenced by a hypoxic environment ex vivo. Methods ：Passage 3 of bone marrow MSCs taken from Wistar rats,were cultured in a culturing chamber with 94%N2,1%O2,5%CO2 at 37℃. At different hypoxia time points ,0,0.5, 1,4 and 8 h, glucose uptake was assayed by using radiation isotope ^3H-G, Apoptotic Rate（AR） and dead rate（DR） were analyzed by flow cytometry（FCM） after Annexin V/PI staining, cell multiplication（by MTr methods） and p-Akt protein by immunocytochemistry and western blot. Results ：Assay for CD29^± ,CD44^± ,CD71^± ,CD34^-, Tn T^±（after 5-azacytidine agent inducing） and ALP^±（after bone differentiation agent inducing） suggested these bone-derived cells were MSCs. The ^3H-G intaking ratio （CPM/ flask value：157 ± 11,110 ± 11,107 ± 13,103 ± 10,100 ± 9 and 98 ± 10） of MSCs at different hypoxia time points, significantly decreased compared to that of normoxia（P 〈 0.01） and tended to descend slowly with hypoxia time duration, for which there was no statistical significance（P 〉 0.05）. The AR（0.09 ± 2.03%,12.9 ± 1.72%,13.7 ± 2.26%,13.8 ± 3.01%,14.1 ± 2.78% and 14.7 ± 4.01% at 0,0.5,1,4 and 8 h,respectively,P 〈 0.01） and DR （0.04, ± 1.79% ,0.93 ± 1.85% ,3.11 ± 2.14% ,4.09 ± 2.36% ,4.72 ± 2.05% and 4.91 ± 3.72% at 0,0.5,1,4 and 8 h, respectively, P 〈 0.05） at different hypoxia time points significantly increased compared to those time in normoxia; The AR further went up with time （P 〈 0.05）, however there was no statistical significance （P 〉 0.05） for the DR. Optical absorption value of MTr methods at different hypoxia time points significantly decreased compared to those with a corresponding normoxia time （P 〈 0.01） and degraded with time （in an hypoxic environment -P 〈 0.01）. IOD of p-Akt protein of MSCs at different hypoxia time points significantly increased （0.367 ± 0.031,0.556 ± 0.023,0.579 ± 0.013, 0.660 ± 0.024, 0.685 ± 0.039 and 0.685 ± 0.011, respectively） compared to their equivalents in normoxia （P〈0.05）, however, there was no statistical significance （P 〉 0.05） for different hypoxia time points. Hypoxia may result in ultramicrostructure changes, such as defluvium of Microvilli, apoptotic body, ＂margination＂ and so on and are further aggravated with hypoxia time stretching. Conclusion： Hypoxia may lead to a depression of MSCs intaldng glucose, creep of cell multiplication, upregulation of p-Akt protein and apoptosis of MSCs ex vivo.
基金supported by the National Natural Science Foundation(Nos.22022801,21878016)National Key Research and Development Program of China(No.2016YFB0301601)the Fundamental Research Funds for the Central Universities(Nos.BHYC1701B,JD2004)。
文摘The interaction between the metal and the support of supported metal catalysts, which are widely used in industry, is the primary focus of the study of such catalysts. With the developing understanding of the metal–support interaction, the intrinsic factor that influences the catalytic performance has been determined to be the structure of interfacial sites. Layered double hydroxides(LDHs, a class of two-dimensional layered anion clay) possess several unique characteristics, such as the following:(1) tunable elemental component, homogeneous distribution of metal cations.(2) anchoring eff ect.(3) multiple layered structure for exfoliation or intercalation and special memory eff ect;and(4) internal/external confinement eff ects during topological transformation. Taking LDHs and their derivatives as precursors or supports shows superior advantages in designing interfacial active catalysts with tunable properties. Therefore, this review is mainly focused on constructing interfacial active catalysts by LDHs and revealing the interfacial eff ects(including electronic, geometric, and bifunctional eff ects) on the catalytic performance that will provide new perspectives and approaches for the development of heterogeneous catalysis.
基金Supported by National Key Research and Development Project of China(Grant No.2022YFB3303303)Zhejiang Provincial Research and Development Project of China(Grant No.LGG22E050010)Key Open Fund of State Key Laboratory of Materials Processing and Die and Mould Technology of China(Grant No.P2024-001).
文摘This paper proposes a deformation evolution and perceptual prediction methodology for additive manufacturing of lightweight composite driven by hybrid digital twins(HDT).In order to improve manufacturing quality of irregular lightweight composite through boosting conceptual design in aeronautic and aerospace engineering,the HDT meaning hybridization of physical and digital domains,including deformation and energy efficiency can be built,where the essential parameters can be perceptually predicted in advance,by virtue of the fusion of physical sensors and digital information.The long short term memory(LSTM)can be employed to void vanishing gradient problem and improve predicting precision via Recurrent Neural Networks,thereby laying a foundation for the HDT.The diverse manufacturing requirements of different regions are integrated into the parameters designing phase by attaching region weights confirmed via empiricism and in-service simulation.The effects of slicing strategy and external support structures on manufacturing quality are considered from the perspective of improving dimensional accuracy.The manufacturing efficiency and comprehensive costs are accounted as consideration factors,which are perceptually predicted via LSTM.The designed manufacturing parameters through HDT were virtually examined by evaluating the deformation and equivalent stress distributions of fabricated lightweight component with composite material through AM process simulation.The physical experiments were conducted to verify the HDT-based pre-designing and optimization method of manufacturing parameters via fused deposition modeling(FDM).The energy consumption of actual manufacturing process was measured via digital power meter and applied to evaluate accuracy of perceptual prediction outcomes.The dimensional accuracy and distortion distribution of the manufactured lightweight prototype made with composite material were measured through the coordinate measuring machine(CMM)and 3D optical scanner.The proposed method demonstrates effectiveness in improving manufacturing quality and accurately predicting energy consumption,which have been verified with a three-way solenoid valve element,in which the maximum deformation was reduced by 39.78%and the mean absolute percentage error for perceptual prediction was 3.76%.
基金financially supported by the National Key R&D Program of China(No.2024YFE0108800/T24KITG014)the National Natural Science Foundation of China(No:52475411)the International Partnership Program of Chinese Academy of Sciences(No.172GJHZ2022096FN)。
文摘Taking half-tube part with curvature as an example,the Impact Hydroforming(IHF)characteristics were studied by combining the actual forming experiment and numerical simulation.The IHF experiment showed that wrinkles appeared at the bottom of the part during single-step forming,but no wrinkles were observed during double-step forming.The thinning rate and deviation of the wall thickness of the part in each area were less than 20%and 2.7 mm,correspondingly,and the drawing depth of the part reached 45.8 mm.The effect of double-step forming was better than that of single-step forming,which was related to the IHF forming law.Besides,the characteristics of the IHF process were studied by numerical simulation.The results indicated that when double-step forming was utilized,there was almost no velocity field in the opposite direction of deformation after the bottom of the part contacted the die,and the existence of stress state at the bottom would restrain and eliminate the wrinkles.The inertia effect evolved with the driving pressure.Specially,the inertia effect can improve the flow of metal and reduce the deviation of the wall thickness of the part under double-step forming.
基金supported by the National Natural Science Foundation(22478016,22288102).
文摘CO_(2)capture and utilization(CCU)are two important processes to address the gigaton challenges in reducing greenhouse gas emissions.Given that both processes are energy-intensive,integrating CO_(2)capture and utilization(ICCU)can improve energy efficiency and reduce economic costs by eliminating steps such as CO_(2)concentration,storage,or capture media regeneration.Aiming at building a bridge between theoretical research and practical application,this review promotes the understanding of high-temperature ICCU,mild/low-temperature ICCU,and emerging electro-/photo-driven ICCU.The reaction mechanism and technical bottleneck are comprehensively evaluated,which could provide a perspective on the design principle of dualfunctional materials(DFMs)combining synergetic adsorptive and catalytic sites.On this basis,novel strategies are proposed from the viewpoint of chemical process intensification to strive for a thermodynamics and kinetics matching between the capture and in situ conversion processes.It is expected that this review can stimulate more research in the future involving expanding the product range,fabricating long-term DFMs,developing a workable reactor,optimizing operation conditions,and establishing an industrial demonstration.
基金supported in main part by the General Project of National Natural Science Foundation of China under Grant 61671194in part by the General Scientific Research Projects of Zhejiang Education Department under Grant Y201840464.
文摘In the application of long series batteries,there is always the phenomenon that multiple cells in a pack are unbalanced simultaneously.In view of this situation,a modevarying cell equalizer topology based on interleaved parallel multiple transformers is proposed in this paper.Every unit in this equalizer can freely switch between LLC resonance mode and 3-state LC quasi-resonance mode.The boosting effect of LLC structure is used to reduce the number of transformer’s total turns.When multiple equalizer units need to work in LLC mode simultaneously,interleaved parallel technology is used to limit secondary side equalization current ripple for long-term protection of battery life.A prototype was designed and built to validate the effect of a closed loop LLC mode control algorithm with a state-of-charge(SOC)based equalization scheme selection strategy.Experimental results including up to 88.52%efficiency in LLC mode with 90.7%efficiency in 3-state LC mode,and minute level balancing time show the proposed topology demonstrates excellent balancing performance.
基金This work was supported by the National Natural Science Foundation(Grants No.22022801,21878016)the National Key Research and Development Program of China(Grant No.2017YFA0206804)Fundamental Research Funds for the Central Universities.
文摘Qualitatively identifying the dominant catalytic site for each step of a semi-continuous reaction and semi-quantitatively correlating such different sites to the catalytic performance is of great significance toward the integration of multiple well-optimized sites on a heterogeneous catalyst.Herein,a series of structurally defined TiO_(x)-based catalysts were synthesized to provide a feasible approach to investigate the aforementioned issues using the semi-continuous oxidation of glycerol as a model reaction.Detailed investigations have verified the simultaneous presence of two kinds of Pt active sites:1)Negatively charged Pt bound to the oxygen vacancies of modified TiO_(x)in the form of Pt^(δ−)-O_(v)-Ti^(3+) sites and 2)metallic Pt(Pt_(0)site)located away from the inter-face.Meanwhile,the proportion of surficial and interfacial sites varies over this series of catalysts.Combined in situ FTIR experiments revealed that the reaction network was well-tuned via a site cooperation mechanism:The surficial Pt_(0)sites dissociatively adsorb the OH group of glycerol with a monodentate bonding geometry and the Pt^(δ−)-O_(v)-Ti^(3+) sites dissociate the C=O bond of the aldehyde group in a bidentate form.Furthermore,CO-FTIR spectroscopy confirmed a correlation between the reaction rate/product selectivity and the fraction of surficial/interfacial sites.A rational proportion of surficial and interfacial sites is key to enabling a high yield of glyceric acid.The most active catalyst with 32%surface sites and 68%interfacial sites exhibited 90.0%glycerol conversion and 68.5%GLYA selectivity.These findings provide a deeper understanding of the structure-activity relationships using qualitative identification and semi-quantitative analysis.
