In this paper,we give a review of some most powerful pulsed systems developed at the Institute of High Current Electronics(HCEI),Siberian Branch,Russian Academy of Sciences,and describe latest achievements of the team...In this paper,we give a review of some most powerful pulsed systems developed at the Institute of High Current Electronics(HCEI),Siberian Branch,Russian Academy of Sciences,and describe latest achievements of the teams dealing with these installations.Besides the presented high-power systems,HCEI performs numerous investigations using much less powerful generators.For instance,last year much attention was paying to the research and development of the intense low-energy(<200 kV)high-current electron and ion beam and plasma sources,and their application in the technology[1-3].展开更多
Based on the pulsed plasma arc welding(PPAW),a rapid remanufacturing shaping system,including a structured light scanning reverse engineering(RE)system,a robot system and a PPAW source system have been developed.The n...Based on the pulsed plasma arc welding(PPAW),a rapid remanufacturing shaping system,including a structured light scanning reverse engineering(RE)system,a robot system and a PPAW source system have been developed.The new rapid remanufacturing shaping system can rapidly and accurately repair the worn parts with different damaged degrees and thus extend their life cycle.In the present paper,the whole process of repairing worn parts is described.Firstly,the scanning model of a worn part is obtained by using RE system based on reconstructing approach.Compared with standard CAD model in the undamaged setting,the surface profile and the extent of damage area are obtained.Secondly,the weld repair path is designed by slicing the point cloud model of damage area.This path consists of multilayer parallel lines that produce parallel overlapped weld beads which cover the damaged area.By off-line programming techniques,the robot executable program as document format is transmitted to the robot controller for repairing worn parts.Finally,the weld repair experiments on worn steel plane plate and damaged column are performed to evaluate the remanufacturing system.展开更多
A theory model is established to describe the voltage-current responsefunction. The peak amplitude and the zero-crossing time of the transient signal is extracted as theimaging features, array pulsed eddy current (PEC...A theory model is established to describe the voltage-current responsefunction. The peak amplitude and the zero-crossing time of the transient signal is extracted as theimaging features, array pulsed eddy current (PEC) imaging is proposed to detect corrosion. The testresults show that this system has the advantage of fast scanning speed, different imaging mode andquantitative detection, it has a broad application in the aviation nondestructive testing.展开更多
Currently, many studies have been made for years on dimensions of pneumatic nozzle, which influence the flow characteristic of blowing system. For the purpose of outputting the same blowing force, the supply pressure ...Currently, many studies have been made for years on dimensions of pneumatic nozzle, which influence the flow characteristic of blowing system. For the purpose of outputting the same blowing force, the supply pressure could be reduced by decreasing the ratio of length to diameter of nozzle. The friction between high speed air and pipe wall would be reduced if the nozzle is designed to be converging shape comparing with straight shape. But the volume flow and pressure, discussed in these studies, do not describe energy loss of the blowing system directly. Pneumatic power is an innovative principle to estimate pneumatic system’s energy consumption directly. Based on the above principle, a pulse blowing method is put forward for saving energy. A flow experiment is carried out, in which the high speed air flows from the pulse blowing system and continuous blowing system respectively to a plate with grease on top. Supply pressure and the volume of air used for removing the grease are measured to calculate energy consumption. From the experiment result, the pulse blowing system performs to conserve energy comparing with the continuous blowing system. The frequency and duty ratio of pulse flow influence the blowing characteristic. The pulse blowing system performs to be the most efficient at the specified frequency and duty ratio. Then a pneumatic self-oscillated method based on air operated valve is put forward to generate pulse flow. A simulation is made about dynamic modeling the air operated valve and calculating the motion of the valve core and output pressure. The simulation result verifies the system to be able to generate pulse flow, and predicts the key parameters of the frequency and duty ratio measured by experiment well. Finally, on the basis of simplifying and solution of the pulse blowing system’s mathematic model, the relationship between system’s frequency duty ratio and the dimensions of components is simply described with four algebraic equations. The system could be designed with specified frequency and duty ratio according to the four equations. This study provides theoretical basis for designing energy-saving air blowing system.展开更多
Photofission enables a unique capability for the domain of non-chemical space propulsion. An ultra-intense laser enables the capacity to induce nuclear fission through the development of bre- msstrahlung photons. A fu...Photofission enables a unique capability for the domain of non-chemical space propulsion. An ultra-intense laser enables the capacity to induce nuclear fission through the development of bre- msstrahlung photons. A fundamental architecture and performance analysis of a photofission pulsed space propulsion system through the operation of an ultra-intense laser is presented. A historical perspective of previous conceptual nuclear fission propulsion systems is addressed. These applications use neutron derived nuclear fission;however, there is inherent complexity that has precluded further development. The background of photofission is detailed. The conceptual architecture of photofission pulsed space propulsion and fundamental performance parameters are established. The implications are the energy source and ultra-intense laser can be situated far remote from the propulsion system. Advances in supporting laser technologies are anticipated to increase the potential for photofission pulsed space propulsion. The fundamental performance analysis of the photofission pulsed space propulsion system indicates the architecture is feasible for further evaluation.展开更多
This experiment designed the pulsed electric fields （PEF） of high intensity of 100 kV· cm^-1 sterilization system. Fluorescent pseudomonas as target cell was operated 180 s in the PEF. By observing the differen...This experiment designed the pulsed electric fields （PEF） of high intensity of 100 kV· cm^-1 sterilization system. Fluorescent pseudomonas as target cell was operated 180 s in the PEF. By observing the difference of the bacteria before and after the disposal by TEM, it is found that the cell walls of the treated bacteria were broken. Irreversible perforations were formed on the cell membrane. The cell inclusions and cell fragments were leaked. The cell died as a result. The results showed that the PEF sterilization system designed can be used for liquid food sterilization experiments.展开更多
A process evaluation system for pulsed gas metal arc welding （GMAW-P） based on the Lab V1EW platform has been developed. This system is comprised of two modules, a simultaneous display module and a data analysis mod...A process evaluation system for pulsed gas metal arc welding （GMAW-P） based on the Lab V1EW platform has been developed. This system is comprised of two modules, a simultaneous display module and a data analysis module. Using these modules, the system can not only provide a comprehensive direct viewing display of the welding electric signal and high speed camera photo, but also can analyze the characteristic parameters of the welding process. The results show that the system works properly.展开更多
As the base of the research work on the weld shape control during pulsed gas tungsten arc welding （GTAW） with wire filler, this paper addressed the modeling of the dynamic welding process. Topside length Lt, maximum...As the base of the research work on the weld shape control during pulsed gas tungsten arc welding （GTAW） with wire filler, this paper addressed the modeling of the dynamic welding process. Topside length Lt, maximum width Wt and half-length ratio Rh1 were selected to depict topside weld pool shape, and were measured on-line by vision sensing. A dynamic neural network model was constructed to predict the usually unmeasured backside width and topside height of the weld through topside shape parameters and welding parameters. The inputs of the model were the welding parameters （peak current, pulse duty ratio, welding speed, filler rate）, the joint gap, the topside pool shape parameters （Lt, Wt, and Rh1）, and their history values at two former pulse, a total of 24 numbers. The validating experiment results proved that the artificial neural network （ANN） model had high precision and could be used in process control. At last, with the developed dynamic model, steady and dynamic behavior was analyzed by simulation experiments, which discovered the variation rules of weld pool shape parameters under different welding parameters, and further knew well the characteristic of the welding process.展开更多
As one of the most important steps in wastewater treatment, limited study on plasma discharge process is a key challenge in the development of plasma applications. In this study, we focus on the plasma discharge proce...As one of the most important steps in wastewater treatment, limited study on plasma discharge process is a key challenge in the development of plasma applications. In this study, we focus on the plasma discharge process of a pulsed diaphragm discharge system. According to the analysis, the pulsed diaphragm discharge proceeds in seven stages： （1） Joule heating and heat exchange stage; （2） nucleated site formation; （3） plasma generation （initiation of the breakdown stage）; （4） avalanche growth and plasma expansion; （5） plasma contraction; （6） termination of the plasma discharge; and （7） heat exchange stage. From this analysis, a critical voltage criterion for breakdown is obtained. We anticipate this finding will provide guidance for a better application of plasma discharges, especially diaphragm plasma discharges.展开更多
A fuzzy logic intelligent control system of pulsed MAG welding inverter based on digital signal processor （DSP） is proposed to obtain the consistency of arc length in pulsed MAG welding. The proposed control system ...A fuzzy logic intelligent control system of pulsed MAG welding inverter based on digital signal processor （DSP） is proposed to obtain the consistency of arc length in pulsed MAG welding. The proposed control system combines the merits of intelligent control with DSP digital control. The fuzzy logic intelligent control system designed is a typical two-input-single-output structure, and regards the error and the change in error of peak arc voltage as two inputs and the background time as single output. The fuzzy logic intelligent control system is realized in a look-up table （LUT） method by using MATLAB based fuzzy logic toolbox, and the implement of LUT method based on DSP is also discussed. The pulsed MAG welding experimental results demonstrate that the developed fuzzy logic intelligent control system based on DSP has strong arc length controlling ability to accomplish the stable pulsed MAG welding process and controls pulsed MAG welding inverter digitally and intelligently.展开更多
A type of novel inverter power supply system for high-power twin-wire pulsed gas metal arc welding （GMAW） is presented mainly for dealing with the disadvantages of the conventional power supply for twin-wire pulsed ...A type of novel inverter power supply system for high-power twin-wire pulsed gas metal arc welding （GMAW） is presented mainly for dealing with the disadvantages of the conventional power supply for twin-wire pulsed GMA W of which the output power is generally difficult to increase due to limitations of the power of semiconductors and the power density of magnetic devices. In the power supplies for the master and slave arcs, the digital signal processor （DSP） TMS320F28335 is used to form the DSP- based synergic control system for parallel high-power pulsed GMA W, which achieves high-power output of two parallel inverters controlled by a single DSP ; master-slave communication is achieved by using e controller area network （eCAN）module of DSP, thas realizing anti-phase pulse output of high-power twin-wire pulsed GMA W and reducing the interference between twin arcs. The experiment results demonstrate that the designed inverter power supply system for high-power twin-wire pulsed GMAW can bring about high-power efficiency of welding, stable welding process and proper formation of welds.展开更多
Digital control system for pulsed MIG welding power based on STM32 is set up with 32-bit STM32FlO3ZET6 directing against the pulse waveform modulation of pulsed MIG welding. High-frequency inverter and medium-low freq...Digital control system for pulsed MIG welding power based on STM32 is set up with 32-bit STM32FlO3ZET6 directing against the pulse waveform modulation of pulsed MIG welding. High-frequency inverter and medium-low frequency pulse waveform modulation of pulsed MIG welding are realized by using the integrated PWM module within STM32 to generate PWM signals of phase-shifted full-bridge soft-switching and constant-current control of output current is achieved by means of anti-windup PI control algorithm to improve the stability and reliability of control system. Experimental results demonstrate that the designed digital control system based on STM32 can achieve pegrect pulsed MIG welding technique with stable welding process and good weld appearance, fully demonstrating the advantages of digital control based on STM32.展开更多
This paper analyses the performance request of arc welding power source used in intelligent control of weld pool shape in pulsed GTAW, and develops a sample power source. The main circuit of the power source takes the...This paper analyses the performance request of arc welding power source used in intelligent control of weld pool shape in pulsed GTAW, and develops a sample power source. The main circuit of the power source takes the structure of single ended inverter with two switches, and takes IGBTs as power switches. The working frequency of the inverter is set at 20 kHz. The control circuit takes PWM circuit as center, and uses single chip computer to complete the manage functions such as the control of working sequence, setting and changing of the welding parameters, sensing of the welding states and communication with outside computer etc. The dynamic reacting time of the whole power is 1 ms, the range of the output current is 5～250 A, the precision of the output current reaches to 1 A. The power strikes arc by contacting workpiece under 5 A, and have convenient interface with system computer. All above shows this power source is one with high performance.展开更多
BACKGROUND Knee and hip osteoarthritis affects millions of people around the world and is expected to rise even more in frequency as the population ages.Joint arthroplasty is the surgical management of choice in these...BACKGROUND Knee and hip osteoarthritis affects millions of people around the world and is expected to rise even more in frequency as the population ages.Joint arthroplasty is the surgical management of choice in these articulations.Heterotopic ossi-fication and radiolucent lines formation are two frequent problems faced in hip and knee replacements respectively.Some studies show that the usage of pulsed lavage may prevent their formation.AIM To compare pulsed lavage to standard lavage in joint arthroplasty.METHODS PubMed,Cochrane,and Google Scholar(page 1-20)were searched till December 2023.Only comparative studies were included.The clinical outcomes evaluated were the heterotopic ossification formation in hip replacements,radiolucent lines formation,and functional knee scores in knee replacements.RESULTS Four studies met the inclusion criteria and were included in this meta-analysis.Pulsed lavage was shown to reduce the formation of radiolucent lines(P=0.001).However,no difference was seen in the remaining outcomes CONCLUSION Pulsed lavage reduced the formation of radiolucent lines in knee replacements.No difference was seen in the remaining outcomes.Furthermore,the clinical significance of these radiolucent lines is poorly understood.Better conducted randomized controlled studies and cost-effectivity studies are needed to reinforce these findings.展开更多
This research investigates the possibility of convergent acoustic waves generation in the liquid by means of the sotmd waves reflection from the solid cylindrical surface, emerged in the pulsed electric discharge. The...This research investigates the possibility of convergent acoustic waves generation in the liquid by means of the sotmd waves reflection from the solid cylindrical surface, emerged in the pulsed electric discharge. The spectra of pulse discharge plasma emission in the water and in the air-water mixture were obtained. The temperature of cuprum and oxygen atoms electronic excitation levels and the temperature tendencies during the discharge current existence were calculated.展开更多
It is necessary to take measures against infectious diseases in the Southeast Asian prawn farming industry. In giant tiger prawn （Penaeus monodon） aquaculture, diseases caused by viruses such as white spot syndrome ...It is necessary to take measures against infectious diseases in the Southeast Asian prawn farming industry. In giant tiger prawn （Penaeus monodon） aquaculture, diseases caused by viruses such as white spot syndrome virus （WSSV） and bacteria such as Vibrio have become a menace. Appropriate treatments of prawn culture pond＇s waters are advocated for preventing and controlling pathogens. The purpose of this study was to conduct an antimicrobial water treatment using a low-voltage pulsed electric field sterilization. Here we prepared a mechanical low-voltage pulsed electric field system with copper wire coiling around a titanium ring. The viability of WSSV in seawater was examined by prawn infectivity experiments. We inoculated healthy prawns （approximately 10-15 g） with the WSSV master sample that passed 0-3 times through the system. WSSV infection in prawns decreased according to the number of passes through the system. Healthy prawns survived for〉 10 days without feeding, where as prawns inoculated with the WSSV master sample showed symptoms of white spot and died in about 4 days. Two-thirds of the prawns inoculated with the WSSV master sample that was passed once through the system developed WSSV symptoms and were polymerase chain reaction （PCR） positive. However, no symptoms were observed and prawns were PCR negative when the WSSV master sample was passed three times through the system. Based on these results, we purpose that a low-voltage pulsed electric field system will serve as an efficient pond drainage sterilization system and will replace conventional treatments using chemicals such as sodium hypochlorite.展开更多
.Pulsed Laser Deposition (PLD) is a powerful technique to grow thin films. Oxides, Magnetics and superconducting materials have been obtained by PLD and theirs properties are strongly dependent of deposition parameter....Pulsed Laser Deposition (PLD) is a powerful technique to grow thin films. Oxides, Magnetics and superconducting materials have been obtained by PLD and theirs properties are strongly dependent of deposition parameters. The construction of a simple and cheap PLD system that is suitable for growing various thin films, including magnetic materials, controlling some deposition parameters is presented. The design characteristics and construction are presented for each one of the devices that compose this PLD system. The equipment has the possibility of carrying out films deposition using up to five targets under controlled atmosphere and substrate temperature. The system also allows controlling the cool off sample time after growing up films at high temperatures. A wide range of relative speeds between target and substrate axial rotation can be externally controlled. With the configuration and the dimensions adopted in their construction, a PLD system of great experimental flexibility is achieved, at a very low cost regarding the commercial systems. To evaluate their performance and effectiveness, the deposition characteristics of a BaFe12O19 film on (0001) sapphire substrate is presented.展开更多
A synergistic photocatalysis combined pulsed diaphragm discharge（PDD）system with TiO_2 nanofilm deposited on the surface of quartz diaphragm is developed for the first time for phenol degradation in an aqueous solut...A synergistic photocatalysis combined pulsed diaphragm discharge（PDD）system with TiO_2 nanofilm deposited on the surface of quartz diaphragm is developed for the first time for phenol degradation in an aqueous solution.It is observed that the decomposition efficiency of phenol in the TiO_2 combined PDD system is higher than that of the single PDD system under the same conditions,indicating a successful collaboration between the photocatalysis and the plasma decomposition in the present system.Analysis of the solution＇s pH value confirms this collaboration and further reveals that the photocatalytic enhancement effect of phenol degradation is strong at a relatively low supplied voltage.The present TiO_2 combined PDD system exhibits improved efficiencies of pollutant degradation and energy utilization,suggesting a good candidate for wastewater treatment.展开更多
Non-metallic inclusions in steel are a significant challenge,affecting material properties and leading to issues such as stress concentration,cracking,and accelerated corrosion.Current methods for removing inclusions,...Non-metallic inclusions in steel are a significant challenge,affecting material properties and leading to issues such as stress concentration,cracking,and accelerated corrosion.Current methods for removing inclusions,including bubble,electromagnetic stirring,filtration separation,fluid flow,and sedimentation,often struggle with the removal of fine inclusions.Apart from these known methods,pulsed electric current(PEC),as an emerging technology,has demonstrated immense potential and environmental advantages.PEC offers adjustable current parameters and simple equipment,making it an attractive alternative to traditional methods.Its green energy-saving features and excellent results in regulating inclusion morphology and migration,as well as inhibiting submerged entry nozzle(SEN)clogging,make it a promising technology.In comparison to continuous current technology,PEC has shown significant advantages in regulating inclusions,not only improving purification efficiency but also demonstrating outstanding performance in flow stability and energy consumption.The ability of PEC to efficiently reduce inclusion numbers enhances the purity and quality of molten steel,improving its mechanical properties.Currently,the theoretical basis for controlling the movement of inclusions by current is mainly composed of three major theories:the double electric layer theory,electromagnetic force reverse separation theory,and electric free energy drive theory.These theories together form an important framework for researchers to understand and optimize the behavior of impurity movement controlled by electric current.Looking ahead,PEC is expected to pave the way for new solutions in directional regulation of inclusion migration,efficient inclusion removal,SEN clogging prevention,and the purification of molten steel.展开更多
The transition of hydrogen sourcing from carbon-intensive to water-based methodologies is underway,with renewable energy-powered proton exchange membrane water electrolysis(PEMWE)emerging as the preeminent pathway for...The transition of hydrogen sourcing from carbon-intensive to water-based methodologies is underway,with renewable energy-powered proton exchange membrane water electrolysis(PEMWE)emerging as the preeminent pathway for hydrogen production.Despite remarkable advancements in this field,confronting the sluggish electrochemical kinetics and inherent high-energy consumption arising from deteriorated mass transport within PEMWE systems remains a formidable obstacle.This impediment stems primarily from the hindered protons mass transfer and the untimely hydrogen bubbles detachment.To address these challenges,we harness the inherent variability of electrical energy and introduce an innovative pulsed dynamic water electrolysis system.Compared to constant voltage electrolysis(hydrogen production rate:51.6 m L h^(-1),energy consumption:5.37 kWh Nm-^(3)H_(2)),this strategy(hydrogen production rate:66 m L h^(-1),energy consumption:3.83 kWh Nm-^(3)H_(2))increases the hydrogen production rate by approximately 27%and reduces the energy consumption by about 28%.Furthermore,we demonstrate the practicality of this system by integrating it with an off-grid photovoltaic(PV)system designed for outdoor operation,successfully driving a hydrogen production current of up to 500 mA under an average voltage of approximately 2 V.The combined results of in-situ characterization and finite element analysis reveal the performance enhancement mechanism:pulsed dynamic electrolysis(PDE)dramatically accelerates the enrichment of protons at the electrode/solution interface and facilitates the release of bubbles on the electrode surface.As such,PDE-enhanced PEMWE represents a synergistic advancement,concurrently enhancing both the hydrogen generation reaction and associated transport processes.This promising technology not only redefines the landscape of electrolysis-based hydrogen production but also holds immense potential for broadening its application across a diverse spectrum of electrocatalytic endeavors.展开更多
基金supported in part by Russian Foundation for Basic Research(project No.15-08-01324).
文摘In this paper,we give a review of some most powerful pulsed systems developed at the Institute of High Current Electronics(HCEI),Siberian Branch,Russian Academy of Sciences,and describe latest achievements of the teams dealing with these installations.Besides the presented high-power systems,HCEI performs numerous investigations using much less powerful generators.For instance,last year much attention was paying to the research and development of the intense low-energy(<200 kV)high-current electron and ion beam and plasma sources,and their application in the technology[1-3].
文摘Based on the pulsed plasma arc welding(PPAW),a rapid remanufacturing shaping system,including a structured light scanning reverse engineering(RE)system,a robot system and a PPAW source system have been developed.The new rapid remanufacturing shaping system can rapidly and accurately repair the worn parts with different damaged degrees and thus extend their life cycle.In the present paper,the whole process of repairing worn parts is described.Firstly,the scanning model of a worn part is obtained by using RE system based on reconstructing approach.Compared with standard CAD model in the undamaged setting,the surface profile and the extent of damage area are obtained.Secondly,the weld repair path is designed by slicing the point cloud model of damage area.This path consists of multilayer parallel lines that produce parallel overlapped weld beads which cover the damaged area.By off-line programming techniques,the robot executable program as document format is transmitted to the robot controller for repairing worn parts.Finally,the weld repair experiments on worn steel plane plate and damaged column are performed to evaluate the remanufacturing system.
文摘A theory model is established to describe the voltage-current responsefunction. The peak amplitude and the zero-crossing time of the transient signal is extracted as theimaging features, array pulsed eddy current (PEC) imaging is proposed to detect corrosion. The testresults show that this system has the advantage of fast scanning speed, different imaging mode andquantitative detection, it has a broad application in the aviation nondestructive testing.
文摘Currently, many studies have been made for years on dimensions of pneumatic nozzle, which influence the flow characteristic of blowing system. For the purpose of outputting the same blowing force, the supply pressure could be reduced by decreasing the ratio of length to diameter of nozzle. The friction between high speed air and pipe wall would be reduced if the nozzle is designed to be converging shape comparing with straight shape. But the volume flow and pressure, discussed in these studies, do not describe energy loss of the blowing system directly. Pneumatic power is an innovative principle to estimate pneumatic system’s energy consumption directly. Based on the above principle, a pulse blowing method is put forward for saving energy. A flow experiment is carried out, in which the high speed air flows from the pulse blowing system and continuous blowing system respectively to a plate with grease on top. Supply pressure and the volume of air used for removing the grease are measured to calculate energy consumption. From the experiment result, the pulse blowing system performs to conserve energy comparing with the continuous blowing system. The frequency and duty ratio of pulse flow influence the blowing characteristic. The pulse blowing system performs to be the most efficient at the specified frequency and duty ratio. Then a pneumatic self-oscillated method based on air operated valve is put forward to generate pulse flow. A simulation is made about dynamic modeling the air operated valve and calculating the motion of the valve core and output pressure. The simulation result verifies the system to be able to generate pulse flow, and predicts the key parameters of the frequency and duty ratio measured by experiment well. Finally, on the basis of simplifying and solution of the pulse blowing system’s mathematic model, the relationship between system’s frequency duty ratio and the dimensions of components is simply described with four algebraic equations. The system could be designed with specified frequency and duty ratio according to the four equations. This study provides theoretical basis for designing energy-saving air blowing system.
文摘Photofission enables a unique capability for the domain of non-chemical space propulsion. An ultra-intense laser enables the capacity to induce nuclear fission through the development of bre- msstrahlung photons. A fundamental architecture and performance analysis of a photofission pulsed space propulsion system through the operation of an ultra-intense laser is presented. A historical perspective of previous conceptual nuclear fission propulsion systems is addressed. These applications use neutron derived nuclear fission;however, there is inherent complexity that has precluded further development. The background of photofission is detailed. The conceptual architecture of photofission pulsed space propulsion and fundamental performance parameters are established. The implications are the energy source and ultra-intense laser can be situated far remote from the propulsion system. Advances in supporting laser technologies are anticipated to increase the potential for photofission pulsed space propulsion. The fundamental performance analysis of the photofission pulsed space propulsion system indicates the architecture is feasible for further evaluation.
基金the Youth Science Fund of Heilongjiang Province (QC07C39)Postdoctoral Fund of Heilongjiang (LBH-Z06163)Science Research Fund of Northeast Agricultural University
文摘This experiment designed the pulsed electric fields （PEF） of high intensity of 100 kV· cm^-1 sterilization system. Fluorescent pseudomonas as target cell was operated 180 s in the PEF. By observing the difference of the bacteria before and after the disposal by TEM, it is found that the cell walls of the treated bacteria were broken. Irreversible perforations were formed on the cell membrane. The cell inclusions and cell fragments were leaked. The cell died as a result. The results showed that the PEF sterilization system designed can be used for liquid food sterilization experiments.
文摘A process evaluation system for pulsed gas metal arc welding （GMAW-P） based on the Lab V1EW platform has been developed. This system is comprised of two modules, a simultaneous display module and a data analysis module. Using these modules, the system can not only provide a comprehensive direct viewing display of the welding electric signal and high speed camera photo, but also can analyze the characteristic parameters of the welding process. The results show that the system works properly.
基金This work was supported by the National Natural Sci-ence Foundation of China(Grant No.59635160)the Weapon Pre-Research Foundation of China(Grant No.51418050404HT0159).
文摘As the base of the research work on the weld shape control during pulsed gas tungsten arc welding （GTAW） with wire filler, this paper addressed the modeling of the dynamic welding process. Topside length Lt, maximum width Wt and half-length ratio Rh1 were selected to depict topside weld pool shape, and were measured on-line by vision sensing. A dynamic neural network model was constructed to predict the usually unmeasured backside width and topside height of the weld through topside shape parameters and welding parameters. The inputs of the model were the welding parameters （peak current, pulse duty ratio, welding speed, filler rate）, the joint gap, the topside pool shape parameters （Lt, Wt, and Rh1）, and their history values at two former pulse, a total of 24 numbers. The validating experiment results proved that the artificial neural network （ANN） model had high precision and could be used in process control. At last, with the developed dynamic model, steady and dynamic behavior was analyzed by simulation experiments, which discovered the variation rules of weld pool shape parameters under different welding parameters, and further knew well the characteristic of the welding process.
基金supported by National Natural Science Foundation of China(Nos.11205202,21203204 and 11175214)Natural Science Foundation of Anhui Province,China (No.1308085QA09)
文摘As one of the most important steps in wastewater treatment, limited study on plasma discharge process is a key challenge in the development of plasma applications. In this study, we focus on the plasma discharge process of a pulsed diaphragm discharge system. According to the analysis, the pulsed diaphragm discharge proceeds in seven stages： （1） Joule heating and heat exchange stage; （2） nucleated site formation; （3） plasma generation （initiation of the breakdown stage）; （4） avalanche growth and plasma expansion; （5） plasma contraction; （6） termination of the plasma discharge; and （7） heat exchange stage. From this analysis, a critical voltage criterion for breakdown is obtained. We anticipate this finding will provide guidance for a better application of plasma discharges, especially diaphragm plasma discharges.
基金supported by National Natural Science Foundation of China(No.50375054)China Postdoctoral Science Foundation (No.20060400745).
文摘A fuzzy logic intelligent control system of pulsed MAG welding inverter based on digital signal processor （DSP） is proposed to obtain the consistency of arc length in pulsed MAG welding. The proposed control system combines the merits of intelligent control with DSP digital control. The fuzzy logic intelligent control system designed is a typical two-input-single-output structure, and regards the error and the change in error of peak arc voltage as two inputs and the background time as single output. The fuzzy logic intelligent control system is realized in a look-up table （LUT） method by using MATLAB based fuzzy logic toolbox, and the implement of LUT method based on DSP is also discussed. The pulsed MAG welding experimental results demonstrate that the developed fuzzy logic intelligent control system based on DSP has strong arc length controlling ability to accomplish the stable pulsed MAG welding process and controls pulsed MAG welding inverter digitally and intelligently.
基金Supported by National Natural Science Foundation of China(No.51205136)Ph.D. Programs Foundation of the Ministry of Education of China(No.20100172120003)+1 种基金Competitive Allocation Project Special Fund of Guangdong Province Chinese Academy of Sciences Comprehensive Strategic Cooperation(No.2013B091500082)The Fundamental Research Funds for the Central Universities(Key Program)(No.2015ZZ084)
文摘A type of novel inverter power supply system for high-power twin-wire pulsed gas metal arc welding （GMAW） is presented mainly for dealing with the disadvantages of the conventional power supply for twin-wire pulsed GMA W of which the output power is generally difficult to increase due to limitations of the power of semiconductors and the power density of magnetic devices. In the power supplies for the master and slave arcs, the digital signal processor （DSP） TMS320F28335 is used to form the DSP- based synergic control system for parallel high-power pulsed GMA W, which achieves high-power output of two parallel inverters controlled by a single DSP ; master-slave communication is achieved by using e controller area network （eCAN）module of DSP, thas realizing anti-phase pulse output of high-power twin-wire pulsed GMA W and reducing the interference between twin arcs. The experiment results demonstrate that the designed inverter power supply system for high-power twin-wire pulsed GMAW can bring about high-power efficiency of welding, stable welding process and proper formation of welds.
基金This work was supported by the National Natural Science Foundation of China （Grant No. 51205136） , the Specialized Research Fund for the Doctoral Program of Higher Education of China （ Grant No. 20100172120003 ） and the Fundamental Research Funds for the Central Universities （Key Program） （ Grant No. 2013ZZ034）.
文摘Digital control system for pulsed MIG welding power based on STM32 is set up with 32-bit STM32FlO3ZET6 directing against the pulse waveform modulation of pulsed MIG welding. High-frequency inverter and medium-low frequency pulse waveform modulation of pulsed MIG welding are realized by using the integrated PWM module within STM32 to generate PWM signals of phase-shifted full-bridge soft-switching and constant-current control of output current is achieved by means of anti-windup PI control algorithm to improve the stability and reliability of control system. Experimental results demonstrate that the designed digital control system based on STM32 can achieve pegrect pulsed MIG welding technique with stable welding process and good weld appearance, fully demonstrating the advantages of digital control based on STM32.
文摘This paper analyses the performance request of arc welding power source used in intelligent control of weld pool shape in pulsed GTAW, and develops a sample power source. The main circuit of the power source takes the structure of single ended inverter with two switches, and takes IGBTs as power switches. The working frequency of the inverter is set at 20 kHz. The control circuit takes PWM circuit as center, and uses single chip computer to complete the manage functions such as the control of working sequence, setting and changing of the welding parameters, sensing of the welding states and communication with outside computer etc. The dynamic reacting time of the whole power is 1 ms, the range of the output current is 5～250 A, the precision of the output current reaches to 1 A. The power strikes arc by contacting workpiece under 5 A, and have convenient interface with system computer. All above shows this power source is one with high performance.
文摘BACKGROUND Knee and hip osteoarthritis affects millions of people around the world and is expected to rise even more in frequency as the population ages.Joint arthroplasty is the surgical management of choice in these articulations.Heterotopic ossi-fication and radiolucent lines formation are two frequent problems faced in hip and knee replacements respectively.Some studies show that the usage of pulsed lavage may prevent their formation.AIM To compare pulsed lavage to standard lavage in joint arthroplasty.METHODS PubMed,Cochrane,and Google Scholar(page 1-20)were searched till December 2023.Only comparative studies were included.The clinical outcomes evaluated were the heterotopic ossification formation in hip replacements,radiolucent lines formation,and functional knee scores in knee replacements.RESULTS Four studies met the inclusion criteria and were included in this meta-analysis.Pulsed lavage was shown to reduce the formation of radiolucent lines(P=0.001).However,no difference was seen in the remaining outcomes CONCLUSION Pulsed lavage reduced the formation of radiolucent lines in knee replacements.No difference was seen in the remaining outcomes.Furthermore,the clinical significance of these radiolucent lines is poorly understood.Better conducted randomized controlled studies and cost-effectivity studies are needed to reinforce these findings.
文摘This research investigates the possibility of convergent acoustic waves generation in the liquid by means of the sotmd waves reflection from the solid cylindrical surface, emerged in the pulsed electric discharge. The spectra of pulse discharge plasma emission in the water and in the air-water mixture were obtained. The temperature of cuprum and oxygen atoms electronic excitation levels and the temperature tendencies during the discharge current existence were calculated.
文摘It is necessary to take measures against infectious diseases in the Southeast Asian prawn farming industry. In giant tiger prawn （Penaeus monodon） aquaculture, diseases caused by viruses such as white spot syndrome virus （WSSV） and bacteria such as Vibrio have become a menace. Appropriate treatments of prawn culture pond＇s waters are advocated for preventing and controlling pathogens. The purpose of this study was to conduct an antimicrobial water treatment using a low-voltage pulsed electric field sterilization. Here we prepared a mechanical low-voltage pulsed electric field system with copper wire coiling around a titanium ring. The viability of WSSV in seawater was examined by prawn infectivity experiments. We inoculated healthy prawns （approximately 10-15 g） with the WSSV master sample that passed 0-3 times through the system. WSSV infection in prawns decreased according to the number of passes through the system. Healthy prawns survived for〉 10 days without feeding, where as prawns inoculated with the WSSV master sample showed symptoms of white spot and died in about 4 days. Two-thirds of the prawns inoculated with the WSSV master sample that was passed once through the system developed WSSV symptoms and were polymerase chain reaction （PCR） positive. However, no symptoms were observed and prawns were PCR negative when the WSSV master sample was passed three times through the system. Based on these results, we purpose that a low-voltage pulsed electric field system will serve as an efficient pond drainage sterilization system and will replace conventional treatments using chemicals such as sodium hypochlorite.
文摘.Pulsed Laser Deposition (PLD) is a powerful technique to grow thin films. Oxides, Magnetics and superconducting materials have been obtained by PLD and theirs properties are strongly dependent of deposition parameters. The construction of a simple and cheap PLD system that is suitable for growing various thin films, including magnetic materials, controlling some deposition parameters is presented. The design characteristics and construction are presented for each one of the devices that compose this PLD system. The equipment has the possibility of carrying out films deposition using up to five targets under controlled atmosphere and substrate temperature. The system also allows controlling the cool off sample time after growing up films at high temperatures. A wide range of relative speeds between target and substrate axial rotation can be externally controlled. With the configuration and the dimensions adopted in their construction, a PLD system of great experimental flexibility is achieved, at a very low cost regarding the commercial systems. To evaluate their performance and effectiveness, the deposition characteristics of a BaFe12O19 film on (0001) sapphire substrate is presented.
基金supported by National Natural Science Foundation of China(Nos.11205202,21203204 and 11175214)National Natural Science Foundation of Anhui Province(No.1308085QA09)
文摘A synergistic photocatalysis combined pulsed diaphragm discharge（PDD）system with TiO_2 nanofilm deposited on the surface of quartz diaphragm is developed for the first time for phenol degradation in an aqueous solution.It is observed that the decomposition efficiency of phenol in the TiO_2 combined PDD system is higher than that of the single PDD system under the same conditions,indicating a successful collaboration between the photocatalysis and the plasma decomposition in the present system.Analysis of the solution＇s pH value confirms this collaboration and further reveals that the photocatalytic enhancement effect of phenol degradation is strong at a relatively low supplied voltage.The present TiO_2 combined PDD system exhibits improved efficiencies of pollutant degradation and energy utilization,suggesting a good candidate for wastewater treatment.
基金supported by the Fundamental Research Funds for the Central Universities(No.FRF-BD-23-01).
文摘Non-metallic inclusions in steel are a significant challenge,affecting material properties and leading to issues such as stress concentration,cracking,and accelerated corrosion.Current methods for removing inclusions,including bubble,electromagnetic stirring,filtration separation,fluid flow,and sedimentation,often struggle with the removal of fine inclusions.Apart from these known methods,pulsed electric current(PEC),as an emerging technology,has demonstrated immense potential and environmental advantages.PEC offers adjustable current parameters and simple equipment,making it an attractive alternative to traditional methods.Its green energy-saving features and excellent results in regulating inclusion morphology and migration,as well as inhibiting submerged entry nozzle(SEN)clogging,make it a promising technology.In comparison to continuous current technology,PEC has shown significant advantages in regulating inclusions,not only improving purification efficiency but also demonstrating outstanding performance in flow stability and energy consumption.The ability of PEC to efficiently reduce inclusion numbers enhances the purity and quality of molten steel,improving its mechanical properties.Currently,the theoretical basis for controlling the movement of inclusions by current is mainly composed of three major theories:the double electric layer theory,electromagnetic force reverse separation theory,and electric free energy drive theory.These theories together form an important framework for researchers to understand and optimize the behavior of impurity movement controlled by electric current.Looking ahead,PEC is expected to pave the way for new solutions in directional regulation of inclusion migration,efficient inclusion removal,SEN clogging prevention,and the purification of molten steel.
基金National Natural Science Foundation of China(No.52476192,No.52106237)Natural Science Foundation of Heilongjiang Province(No.YQ2022E027)。
文摘The transition of hydrogen sourcing from carbon-intensive to water-based methodologies is underway,with renewable energy-powered proton exchange membrane water electrolysis(PEMWE)emerging as the preeminent pathway for hydrogen production.Despite remarkable advancements in this field,confronting the sluggish electrochemical kinetics and inherent high-energy consumption arising from deteriorated mass transport within PEMWE systems remains a formidable obstacle.This impediment stems primarily from the hindered protons mass transfer and the untimely hydrogen bubbles detachment.To address these challenges,we harness the inherent variability of electrical energy and introduce an innovative pulsed dynamic water electrolysis system.Compared to constant voltage electrolysis(hydrogen production rate:51.6 m L h^(-1),energy consumption:5.37 kWh Nm-^(3)H_(2)),this strategy(hydrogen production rate:66 m L h^(-1),energy consumption:3.83 kWh Nm-^(3)H_(2))increases the hydrogen production rate by approximately 27%and reduces the energy consumption by about 28%.Furthermore,we demonstrate the practicality of this system by integrating it with an off-grid photovoltaic(PV)system designed for outdoor operation,successfully driving a hydrogen production current of up to 500 mA under an average voltage of approximately 2 V.The combined results of in-situ characterization and finite element analysis reveal the performance enhancement mechanism:pulsed dynamic electrolysis(PDE)dramatically accelerates the enrichment of protons at the electrode/solution interface and facilitates the release of bubbles on the electrode surface.As such,PDE-enhanced PEMWE represents a synergistic advancement,concurrently enhancing both the hydrogen generation reaction and associated transport processes.This promising technology not only redefines the landscape of electrolysis-based hydrogen production but also holds immense potential for broadening its application across a diverse spectrum of electrocatalytic endeavors.
