Lithium iron phosphate batteries have been increasingly utilized in recent years because their higher safety performance can improve the increasing trend of recurring thermal runaway accidents.However,the safety perfo...Lithium iron phosphate batteries have been increasingly utilized in recent years because their higher safety performance can improve the increasing trend of recurring thermal runaway accidents.However,the safety performance and mechanism of high-capacity lithium iron phosphate batteries under internal short-circuit challenges remain to be explored.This work analyzes the thermal runaway evolution of high-capacity LiFePO_(4) batteries under different internal heat transfer modes,which are controlled by different penetration modes.Two penetration cases involving complete penetration and incomplete penetration were detected during the test,and two modes were performed incorporating nails that either remained or were removed after penetration to comprehensively reveal the thermal runaway mechanism.A theoretical model of microcircuits and internal heat conduction is also established.The results indicated three thermal runaway evolution processes for high-capacity batteries,which corresponded to the experimental results of thermal equilibrium,single thermal runaway,and two thermal runaway events.The difference in heat distribution in the three phenomena is determined based on the microstructure and material structure near the pinhole.By controlling the heat dissipation conditions,the time interval between two thermal runaway events can be delayed from 558 to 1417 s,accompanied by a decrease in the concentration of in-situ gas production during the second thermal runaway event.展开更多
Using Xenon lamp lights to overcome the strong interference from the welding arc, a computer-based system is developed to sense and visualize the metal transfer in GMAW. This system combines through-the-arc sensing of...Using Xenon lamp lights to overcome the strong interference from the welding arc, a computer-based system is developed to sense and visualize the metal transfer in GMAW. This system combines through-the-arc sensing of the welding current and arc voltage with high speed imaging of the metal transfer. It can simultaneously display the metal transfer processes and waveforms of electrical welding parameters in real-time The metal transfer videos and waveforms of electrical welding parameters can be recorded. Metal transfers under various welding conditions have been investigated with the system developed.展开更多
Ultrasonic assisted GMAW （U-GMAW） method is a novel process, which combines the ultrasonic wave with gas metal arc welding to improve the process stability and weld quality. The U-GMAW system is developed and the ul...Ultrasonic assisted GMAW （U-GMAW） method is a novel process, which combines the ultrasonic wave with gas metal arc welding to improve the process stability and weld quality. The U-GMAW system is developed and the ultrasonic wave is applied by means of acoustic radiation. The arc characteristics and metal transfer modes are studied in comparison with conventional GMAW process. The arc plasma is compressed and the arc length is shorter than that in conventional GMAW process after the ultrasonic is applied onto the arc. The parameter range of short-circuiting mode is extended and the range of unstable transfer is minimized. The changes in arc characteristics are responsible for changes in metal transfer modes.展开更多
This paper introduces a method to realize digital television transmission based on asynchronous transfer mode (ATM), a technology based on fast packet switching. Choosing the integral multiple length of an ATM cell pa...This paper introduces a method to realize digital television transmission based on asynchronous transfer mode (ATM), a technology based on fast packet switching. Choosing the integral multiple length of an ATM cell payload to equal to the length of an MPEG transport stream packet, an MPEG transport stream packet can be inextenso loaded by several ATM cells and trans-formed into ATM cells. Using ATM virtual connection technology and B-ISDN, the interoperability between ATM and DTV may be realized, and DTV signal transmission may also be realized finally.展开更多
With the full-speed development of economy,the new urbanization has been accelerated in Guizhou Province in order to make the people reach a well-off standard of living by 2020. From the whole society,the key point is...With the full-speed development of economy,the new urbanization has been accelerated in Guizhou Province in order to make the people reach a well-off standard of living by 2020. From the whole society,the key point is the development of the rural economy,and the development of the rural economy depends on the economic development of rural households. The income from rural labor force transfer has become the main income source and accounts for more than half of rural household income,which will play a major role in survival and development of rural households.展开更多
When laser ablation is subjected to supersonic flow, the influence mechanism of airflow on laser ablation behavior is still unclear. A coupled thermal-fluid-structure model is presented to investigate the influence of...When laser ablation is subjected to supersonic flow, the influence mechanism of airflow on laser ablation behavior is still unclear. A coupled thermal-fluid-structure model is presented to investigate the influence of supersonic airflow on the development of a laser ablation pit. Results show that the aerodynamic convection cooling effect not only reduces the ablation velocity but also changes the symmetry morphology of the ablation pit due to the non-uniform convective heat transfer. Flow mode transition is also observed when the pit becomes deeper, and significant change in flow pattern and heat transfer behavior are found when the open mode is transformed into the closed mode.展开更多
Objective: To explore the clinical value of safe transfer nursing model in hospital transfer of critically ill patients in emergency department. Methods: 850 critically ill patients admitted to the emergency departmen...Objective: To explore the clinical value of safe transfer nursing model in hospital transfer of critically ill patients in emergency department. Methods: 850 critically ill patients admitted to the emergency department of the central hospital were selected as the observation group (the implementation of safe transport care model), 660 critically ill patients admitted to the emergency department of the central hospital from April to December 2019 were selected as the control group (the use of regular car escort), and the occurrence of adverse events, transit time and satisfaction of patients' families were compared between the two groups. Results: the total incidence rate of adverse events in the observation group was 1.76%, which was significantly lower than that in the control group (10.00%) (P < 0.05). The time taken for external examination, including ultrasound, CT and X-ray, in the observation group was (26.12±3.11) min, time taken for transfer to specialized department (21.18±3.13) min and time taken for transfer to interventional room (5.32±1.19) min, which were significantly shorter than those in the control group (34.25±4.27), (25.33±3.07) min and (6.16±1.32) min, with statistical significance (P < 0.05). The scores of nurse-patient communication, care in transit, and treatment in the department and the total score in the observation group were (21.52±5.32), (34.56±7.13), (25.34±6.32) and (76.35±11.26) respectively, which were significantly higher than those in the control group (20.33±4.78), (32.33±6.25), (22.33±6.41) and (73.62±11.09), with statistical significance (P < 0.05). Conclusion: the safe transfer nursing model has high clinical value in the hospital transfer of critically ill patients in emergency department, which can effectively reduce the risk of adverse events, shorten the transfer time and improve the satisfaction of patients' families.展开更多
In this paper, an extended Kendall model for the priority scheduling input-line group output with multi-channel in Asynchronous Transfer Mode （ATM） exchange system is proposed and then the mean method is used to mod...In this paper, an extended Kendall model for the priority scheduling input-line group output with multi-channel in Asynchronous Transfer Mode （ATM） exchange system is proposed and then the mean method is used to model mathematically the non-typical non-anticipative PRiority service （PR） model. Compared with the typical and non-anticipative PR model, it expresses the characteristics of the priority scheduling input-line group output with multi-channel in ATM exchange system. The simulation experiment shows that this model can improve the HOL block and the performance of input-queued ATM switch network dramatically. This model has a better developing prospect in ATM exchange system.展开更多
Digital TV (DTV) video signal transmission over ATM network is emphasized on.Some important problems are introduced about TV video signals asynchronous transfer to network application client, and the idea of video tra...Digital TV (DTV) video signal transmission over ATM network is emphasized on.Some important problems are introduced about TV video signals asynchronous transfer to network application client, and the idea of video transfer design is discussed. The contents mainly include the DTV video streams asynchronous transfer topology, compressed coding adopted ATM network, asynchronous transfer efficiency and some problems of DTV video transmission in ATM network .展开更多
The literature suggests that protection of knowledge from the threat for opportunism is a primary mover for the choice of entry mode.However,the knowledge construct is oversimplified in the literature on entry mode.Th...The literature suggests that protection of knowledge from the threat for opportunism is a primary mover for the choice of entry mode.However,the knowledge construct is oversimplified in the literature on entry mode.The combination of different types of knowledge held by a firm reduces the risk of misappropriation and the threat of opportunism is often unimportant in entry mode decisions.Based on these discussions,a new conceptual knowledgebased model of entry mode choice is devoloped.In this model,the knowledge is classified into business knowledge and location knowledge,the strategies into exploitation and exploration.This model focuses on two main attributes of knowledge,namely,embedded ness and complementarity.It is suggested that embedded ness and complementarity of business knowledge and location knowledge affect the entry mode choice.The knowledge strategies moderate the relationships between the attributes of knowledge and entry mode.Transferring capacity is also introduced in this model.展开更多
Elastic heat transfer tube bundles are widely used in the field of flow-induced vibration heat transfer enhancement. Two types of mainly used tube bundles, the planar elastic tube bundle and the conical spiral tube bu...Elastic heat transfer tube bundles are widely used in the field of flow-induced vibration heat transfer enhancement. Two types of mainly used tube bundles, the planar elastic tube bundle and the conical spiral tube bundle were comprehensively compared in the condition of the same shell side diameter. The natural mode characteristics, the effect of fluid-structure interaction, the stress distribution, the comprehensive heat transfer performance and the secondary fluid flow of the two elastic tube bundles were all concluded and compared. The results show that the natural frequency and the critical velocity of vibration buckling of the planar elastic tube bundle are larger than those of the conical spiral tube bundle, while the stress distribution and the comprehensive heat transfer performance of the conical spiral tube bundle are relatively better.展开更多
Based on the analysis of material motion in the axial direction, heat transfer and mass transport processes in a rotary kiln, and combining with pulverized coal combustion, material pyrogenation, cooling of furnace wa...Based on the analysis of material motion in the axial direction, heat transfer and mass transport processes in a rotary kiln, and combining with pulverized coal combustion, material pyrogenation, cooling of furnace wall finally, and heat transfer and mass transport equations, the combined heat transfer mathematical model for alumina rotary kiln was built up. According to the in-site real operation parameters, the heat transfer mathematical model was solved numerically for an alumina rotary kiln to predict the temperature profiles of gas and material in the axial direction. The results show that as the excess air coefficient reduces from 1.38 to 1.20, the temperature of the sintering zone increases and the length decreases. However, as the excess air coefficient reduces from 1.20 to 1.10, the temperature of the sintering zone decreases and the length increases. When the mixed coal amount at the end of kiln is reduced from 68.6 kg/t to 62.0 kg/t and the burned coal amount at the head of kiln correspondingly increases from 155.3 kg/t to 161.9 kg/t, the sintering zone temperature increases and the length reduces. The suitable excess air coefficient and mixed coal amount at the end of kiln are recommended for the rotary kiln operation optimization.展开更多
It has been reported that, through the evanescent near fields, the strongly coupled magnetic resonance is able to achieve an efficient mid-range Wireless Power Transfer (WPT) beyond the characteristic size of the reso...It has been reported that, through the evanescent near fields, the strongly coupled magnetic resonance is able to achieve an efficient mid-range Wireless Power Transfer (WPT) beyond the characteristic size of the resonator. Recent studies on of the relay effect of the WPT allow more distant and flexible energy transmission. These new developments hold a promise to construct a fully wireless Body Sensor Network (wBSN) using the new mid-range WPT theory. In this paper, a general optimization strategy for a WPT network is presented by analysis and simulation using the coupled mode theory. Based on the results of theoretical and computational study, two types of thin-film resonators are designed and prototyped for the construction of wBSNs. These resonators and associated electronic components can be integrated into a WPT platform to permit wireless power delivery to multiple wearable sensors and medical implants on the surface and within the human body. Our experiments have demonstrated the feasibility of the WPT approach.展开更多
Metal transfer of twin-wire indirect arc argon welding was investigated with high speed camcorder system based on a xenon lamp source and digital oscillograph, forces on droplet were analyzed in this paper. Results sh...Metal transfer of twin-wire indirect arc argon welding was investigated with high speed camcorder system based on a xenon lamp source and digital oscillograph, forces on droplet were analyzed in this paper. Results show metal transfer mode that of anodal and cathodal is not completely the same. It was divided into seven types of transfer mode; spray transfer and spray-projected transfer are the important transfer mode. The base-plate was melted by energy that of the arc and drop carrying, the drop transfer direction is different from that of the current flow, anodal and cathodal drop transfer at the same time, only the frequence and size are different.展开更多
The dynamic performance of the coupling shaft system in a carpet tufting machine is the most critical factor affecting the carpet tufting machine's efficiency,and the product quality of the tufted carpet. To deter...The dynamic performance of the coupling shaft system in a carpet tufting machine is the most critical factor affecting the carpet tufting machine's efficiency,and the product quality of the tufted carpet. To determine how to avoid resonance produced by the coupling shaft system's vibration during the weaving process,the dynamic performance of a coupling shaft system in a carpet tufting machine was analyzed. Focusing on a DHGN801D-400 carpet tufting machine,a dynamic model of coupling shaft system was established by utilizing transfer matrix methodology. On the basis of this model,the natural frequencies and mode shapes of the coupling shaft system were obtained through simulations. The correctness of the theoretical model and the dynamic performance of the coupling shaft system were validated by experiments. The first order natural frequency of the coupling shaft system was close to 600 r / min. A conclusion can thus be drawn that operating the carpet tufting machine near this speed should be avoided as much as possible.展开更多
A numerical simulation is conducted to investigate arc-anode attachment behavior, especially the formation mechanism of the constricted arc attachment mode for the water-cooled anode of wall-stabilized transferred arg...A numerical simulation is conducted to investigate arc-anode attachment behavior, especially the formation mechanism of the constricted arc attachment mode for the water-cooled anode of wall-stabilized transferred argon arcs. Argon molecular ions and the corresponding kinetic processes are included to the finite-rate chemistry model in order to capture the chemical nonequilibrium characteristics of the arc near the anode region. Modeling results show that constricted and diffusive arc–anode attachments can be self-consistently obtained at different arc currents while keeping other parameters unchanged. The dominant kinetic processes contributing to ionization and recombination in the arc center and fringes are presented. The results show that in arc fringes and the arc attachment region, molecular ion recombination plays an important role which leads to the rapid loss of electrons. The radial evolution of the production, loss and transport processes of electrons is further analyzed. It is found that for the constricted arc attachment mode, both the recombination and convection transport caused by the anode jet result in the loss of electrons at the arc fringes, which leads to the shrinkage of the arc column at the anode. The formation of the anode jet is due to the combined action of radial and axial Lorentz forces in the anode region.展开更多
A versatile current-mode biquadratic filter using three operational amplifiers and nine passive elements is proposed. By suitably choosing the output branch, lowpass, bandpass, highpass, bandstop and allpass transfer ...A versatile current-mode biquadratic filter using three operational amplifiers and nine passive elements is proposed. By suitably choosing the output branch, lowpass, bandpass, highpass, bandstop and allpass transfer functions are realized simultaneously without changing the circuit configuration and elements. Two circuits, one is for low frequency application and the other for high frequency, are proposed. The center frequency, quality factor and gain constants of the circuit can be tuned independently. Simulated results show that the circuits work successfully.展开更多
基金supported by the National Key R&D Program of China(2021YFB2402001)the China National Postdoctoral Program for Innovative Talents(BX20220286)+1 种基金the China Postdoctoral Science Foundation(2022T150615)supported by the Youth Innovation Promotion Association CAS(Y201768)。
文摘Lithium iron phosphate batteries have been increasingly utilized in recent years because their higher safety performance can improve the increasing trend of recurring thermal runaway accidents.However,the safety performance and mechanism of high-capacity lithium iron phosphate batteries under internal short-circuit challenges remain to be explored.This work analyzes the thermal runaway evolution of high-capacity LiFePO_(4) batteries under different internal heat transfer modes,which are controlled by different penetration modes.Two penetration cases involving complete penetration and incomplete penetration were detected during the test,and two modes were performed incorporating nails that either remained or were removed after penetration to comprehensively reveal the thermal runaway mechanism.A theoretical model of microcircuits and internal heat conduction is also established.The results indicated three thermal runaway evolution processes for high-capacity batteries,which corresponded to the experimental results of thermal equilibrium,single thermal runaway,and two thermal runaway events.The difference in heat distribution in the three phenomena is determined based on the microstructure and material structure near the pinhole.By controlling the heat dissipation conditions,the time interval between two thermal runaway events can be delayed from 558 to 1417 s,accompanied by a decrease in the concentration of in-situ gas production during the second thermal runaway event.
基金supported by the Opening Project Foundation of MOE Key Laboratory of Liquid Structure and Heredity of Materials and Natural Science foundation of Shandong Province(Grant NO.Y20002F24).
文摘Using Xenon lamp lights to overcome the strong interference from the welding arc, a computer-based system is developed to sense and visualize the metal transfer in GMAW. This system combines through-the-arc sensing of the welding current and arc voltage with high speed imaging of the metal transfer. It can simultaneously display the metal transfer processes and waveforms of electrical welding parameters in real-time The metal transfer videos and waveforms of electrical welding parameters can be recorded. Metal transfers under various welding conditions have been investigated with the system developed.
文摘Ultrasonic assisted GMAW （U-GMAW） method is a novel process, which combines the ultrasonic wave with gas metal arc welding to improve the process stability and weld quality. The U-GMAW system is developed and the ultrasonic wave is applied by means of acoustic radiation. The arc characteristics and metal transfer modes are studied in comparison with conventional GMAW process. The arc plasma is compressed and the arc length is shorter than that in conventional GMAW process after the ultrasonic is applied onto the arc. The parameter range of short-circuiting mode is extended and the range of unstable transfer is minimized. The changes in arc characteristics are responsible for changes in metal transfer modes.
基金Project (No. zk043093) supported by the Introduced Talent Founda-tion of Southwest University of Science and Technology, China
文摘This paper introduces a method to realize digital television transmission based on asynchronous transfer mode (ATM), a technology based on fast packet switching. Choosing the integral multiple length of an ATM cell payload to equal to the length of an MPEG transport stream packet, an MPEG transport stream packet can be inextenso loaded by several ATM cells and trans-formed into ATM cells. Using ATM virtual connection technology and B-ISDN, the interoperability between ATM and DTV may be realized, and DTV signal transmission may also be realized finally.
基金Supported by Research Project of Guizhou Provincial Agriculture Commission in 2013
文摘With the full-speed development of economy,the new urbanization has been accelerated in Guizhou Province in order to make the people reach a well-off standard of living by 2020. From the whole society,the key point is the development of the rural economy,and the development of the rural economy depends on the economic development of rural households. The income from rural labor force transfer has become the main income source and accounts for more than half of rural household income,which will play a major role in survival and development of rural households.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11332011 and 11472276the Project of the Chinese Academy of Sciences,and the Defense Industrial Technology Development Program
文摘When laser ablation is subjected to supersonic flow, the influence mechanism of airflow on laser ablation behavior is still unclear. A coupled thermal-fluid-structure model is presented to investigate the influence of supersonic airflow on the development of a laser ablation pit. Results show that the aerodynamic convection cooling effect not only reduces the ablation velocity but also changes the symmetry morphology of the ablation pit due to the non-uniform convective heat transfer. Flow mode transition is also observed when the pit becomes deeper, and significant change in flow pattern and heat transfer behavior are found when the open mode is transformed into the closed mode.
文摘Objective: To explore the clinical value of safe transfer nursing model in hospital transfer of critically ill patients in emergency department. Methods: 850 critically ill patients admitted to the emergency department of the central hospital were selected as the observation group (the implementation of safe transport care model), 660 critically ill patients admitted to the emergency department of the central hospital from April to December 2019 were selected as the control group (the use of regular car escort), and the occurrence of adverse events, transit time and satisfaction of patients' families were compared between the two groups. Results: the total incidence rate of adverse events in the observation group was 1.76%, which was significantly lower than that in the control group (10.00%) (P < 0.05). The time taken for external examination, including ultrasound, CT and X-ray, in the observation group was (26.12±3.11) min, time taken for transfer to specialized department (21.18±3.13) min and time taken for transfer to interventional room (5.32±1.19) min, which were significantly shorter than those in the control group (34.25±4.27), (25.33±3.07) min and (6.16±1.32) min, with statistical significance (P < 0.05). The scores of nurse-patient communication, care in transit, and treatment in the department and the total score in the observation group were (21.52±5.32), (34.56±7.13), (25.34±6.32) and (76.35±11.26) respectively, which were significantly higher than those in the control group (20.33±4.78), (32.33±6.25), (22.33±6.41) and (73.62±11.09), with statistical significance (P < 0.05). Conclusion: the safe transfer nursing model has high clinical value in the hospital transfer of critically ill patients in emergency department, which can effectively reduce the risk of adverse events, shorten the transfer time and improve the satisfaction of patients' families.
文摘In this paper, an extended Kendall model for the priority scheduling input-line group output with multi-channel in Asynchronous Transfer Mode （ATM） exchange system is proposed and then the mean method is used to model mathematically the non-typical non-anticipative PRiority service （PR） model. Compared with the typical and non-anticipative PR model, it expresses the characteristics of the priority scheduling input-line group output with multi-channel in ATM exchange system. The simulation experiment shows that this model can improve the HOL block and the performance of input-queued ATM switch network dramatically. This model has a better developing prospect in ATM exchange system.
文摘Digital TV (DTV) video signal transmission over ATM network is emphasized on.Some important problems are introduced about TV video signals asynchronous transfer to network application client, and the idea of video transfer design is discussed. The contents mainly include the DTV video streams asynchronous transfer topology, compressed coding adopted ATM network, asynchronous transfer efficiency and some problems of DTV video transmission in ATM network .
文摘The literature suggests that protection of knowledge from the threat for opportunism is a primary mover for the choice of entry mode.However,the knowledge construct is oversimplified in the literature on entry mode.The combination of different types of knowledge held by a firm reduces the risk of misappropriation and the threat of opportunism is often unimportant in entry mode decisions.Based on these discussions,a new conceptual knowledgebased model of entry mode choice is devoloped.In this model,the knowledge is classified into business knowledge and location knowledge,the strategies into exploitation and exploration.This model focuses on two main attributes of knowledge,namely,embedded ness and complementarity.It is suggested that embedded ness and complementarity of business knowledge and location knowledge affect the entry mode choice.The knowledge strategies moderate the relationships between the attributes of knowledge and entry mode.Transferring capacity is also introduced in this model.
基金Projects(xjj2013104,08143063)supported by the Fundamental Research Funds for the Central Universities,ChinaProject(2011CB706606)supported by the National Basic Research Program of China
文摘Elastic heat transfer tube bundles are widely used in the field of flow-induced vibration heat transfer enhancement. Two types of mainly used tube bundles, the planar elastic tube bundle and the conical spiral tube bundle were comprehensively compared in the condition of the same shell side diameter. The natural mode characteristics, the effect of fluid-structure interaction, the stress distribution, the comprehensive heat transfer performance and the secondary fluid flow of the two elastic tube bundles were all concluded and compared. The results show that the natural frequency and the critical velocity of vibration buckling of the planar elastic tube bundle are larger than those of the conical spiral tube bundle, while the stress distribution and the comprehensive heat transfer performance of the conical spiral tube bundle are relatively better.
基金Project(11C26214202599) supported by the SME Technology Innovation Fund of Ministry of Science and Technology,China
文摘Based on the analysis of material motion in the axial direction, heat transfer and mass transport processes in a rotary kiln, and combining with pulverized coal combustion, material pyrogenation, cooling of furnace wall finally, and heat transfer and mass transport equations, the combined heat transfer mathematical model for alumina rotary kiln was built up. According to the in-site real operation parameters, the heat transfer mathematical model was solved numerically for an alumina rotary kiln to predict the temperature profiles of gas and material in the axial direction. The results show that as the excess air coefficient reduces from 1.38 to 1.20, the temperature of the sintering zone increases and the length decreases. However, as the excess air coefficient reduces from 1.20 to 1.10, the temperature of the sintering zone decreases and the length increases. When the mixed coal amount at the end of kiln is reduced from 68.6 kg/t to 62.0 kg/t and the burned coal amount at the head of kiln correspondingly increases from 155.3 kg/t to 161.9 kg/t, the sintering zone temperature increases and the length reduces. The suitable excess air coefficient and mixed coal amount at the end of kiln are recommended for the rotary kiln operation optimization.
文摘It has been reported that, through the evanescent near fields, the strongly coupled magnetic resonance is able to achieve an efficient mid-range Wireless Power Transfer (WPT) beyond the characteristic size of the resonator. Recent studies on of the relay effect of the WPT allow more distant and flexible energy transmission. These new developments hold a promise to construct a fully wireless Body Sensor Network (wBSN) using the new mid-range WPT theory. In this paper, a general optimization strategy for a WPT network is presented by analysis and simulation using the coupled mode theory. Based on the results of theoretical and computational study, two types of thin-film resonators are designed and prototyped for the construction of wBSNs. These resonators and associated electronic components can be integrated into a WPT platform to permit wireless power delivery to multiple wearable sensors and medical implants on the surface and within the human body. Our experiments have demonstrated the feasibility of the WPT approach.
基金Natural Science Foundation of Shandong Province (Z2002F03)College Scientific and Technological Project of Shandong Province (J09LD04)Shandong University of Science and Technology Spring Buds Program (2008BWZ059, 2009AZZ001)
文摘Metal transfer of twin-wire indirect arc argon welding was investigated with high speed camcorder system based on a xenon lamp source and digital oscillograph, forces on droplet were analyzed in this paper. Results show metal transfer mode that of anodal and cathodal is not completely the same. It was divided into seven types of transfer mode; spray transfer and spray-projected transfer are the important transfer mode. The base-plate was melted by energy that of the arc and drop carrying, the drop transfer direction is different from that of the current flow, anodal and cathodal drop transfer at the same time, only the frequence and size are different.
基金Supported by National Natural Science Foundation of P. R. China （60574083）, Key Laboratory of Process Industry Automation, State Education Ministry of China （PAL200514）
基金National Natural Science Foundation of China(No.51175075)the Research and Innovation Project of Shanghai Municipal Education Commission,China(No.15ZZ034)
文摘The dynamic performance of the coupling shaft system in a carpet tufting machine is the most critical factor affecting the carpet tufting machine's efficiency,and the product quality of the tufted carpet. To determine how to avoid resonance produced by the coupling shaft system's vibration during the weaving process,the dynamic performance of a coupling shaft system in a carpet tufting machine was analyzed. Focusing on a DHGN801D-400 carpet tufting machine,a dynamic model of coupling shaft system was established by utilizing transfer matrix methodology. On the basis of this model,the natural frequencies and mode shapes of the coupling shaft system were obtained through simulations. The correctness of the theoretical model and the dynamic performance of the coupling shaft system were validated by experiments. The first order natural frequency of the coupling shaft system was close to 600 r / min. A conclusion can thus be drawn that operating the carpet tufting machine near this speed should be avoided as much as possible.
基金supported by National Natural Science Foundation of China (Nos. 11735004, 11575019, 11702021)the National Postdoctoral Program for Innovative Talents (BX20180029)
文摘A numerical simulation is conducted to investigate arc-anode attachment behavior, especially the formation mechanism of the constricted arc attachment mode for the water-cooled anode of wall-stabilized transferred argon arcs. Argon molecular ions and the corresponding kinetic processes are included to the finite-rate chemistry model in order to capture the chemical nonequilibrium characteristics of the arc near the anode region. Modeling results show that constricted and diffusive arc–anode attachments can be self-consistently obtained at different arc currents while keeping other parameters unchanged. The dominant kinetic processes contributing to ionization and recombination in the arc center and fringes are presented. The results show that in arc fringes and the arc attachment region, molecular ion recombination plays an important role which leads to the rapid loss of electrons. The radial evolution of the production, loss and transport processes of electrons is further analyzed. It is found that for the constricted arc attachment mode, both the recombination and convection transport caused by the anode jet result in the loss of electrons at the arc fringes, which leads to the shrinkage of the arc column at the anode. The formation of the anode jet is due to the combined action of radial and axial Lorentz forces in the anode region.
文摘A versatile current-mode biquadratic filter using three operational amplifiers and nine passive elements is proposed. By suitably choosing the output branch, lowpass, bandpass, highpass, bandstop and allpass transfer functions are realized simultaneously without changing the circuit configuration and elements. Two circuits, one is for low frequency application and the other for high frequency, are proposed. The center frequency, quality factor and gain constants of the circuit can be tuned independently. Simulated results show that the circuits work successfully.
