Abstract: Owing to their high surface area, excellent electrolyte permeability and ample diffusion pathways for charge transport, porous and hollow-structured electrochemically active materials attract more attention as the electrodes. In general, the process of template preparation method is used to achieve hollow structured materials over the last few decades. However, the complicated preparation process including removal of template and surface modification often results in poor uniformity, low reproducibility, and high cost of porous structure. Moreover, it incorporates functional chemicals with specific homogeneity and dispersity into the hollow porous intercrystalline structure. These problems hinder the development and application in energy storage and conversion devices of the diversified porous and hollow-structured materials. The metal-organic frameworks (MOFs), consisting of organic linkers and coordinated inorganic clusters, appear as an excellent collection of porous crystal material series with high surface areas, high porosity, and tunable structures. However, their low conductivity and electrolyte instability limit the further use of MOFs in the field of LIBs. Recently, how electrode materials for Lithium–ion batteries (LIBs) are designed and prepare using MOFs has attracted more attention. The composite materials derived from MOFs including nanostructured porous carbons and metal oxide uaing self-sacrificial template synthetic route not only solves the problem of low conductivity but also maintains the high surface area and porous structure of MOFs, providing abundant active sites for insertion/deinsertion or adsorption/desorption; Furthermore, composite materials derived from MOFs increase the complexity of nanostructures in terms of structural units and chemical components. In particular, large pore volume and open pore structure are critical to loading guest species, accommodating mechanical strains and facilitating mass transport. In this paper, we briefly examined the production of MOF-derived materials for applications in LIBs. The optimization and modification of an MOFs morphology were implemented according to the electrode material requirement for LIBs. Moreover, the preparation of MOFs-derived electrode materials with porous, hollow, or complicated construction and their effects on electrochemical performance were described. Finally, the challenge and trend in production of electrode materials derived from MOFs were analyzed.
Abstract: Compared with the traditional subtractive and equal manufacturing (SM/EM) computer numerical control (CNC) machining, press working, and casting, additive manufacturing (AM) technology has great advantages in the construction of high-complexity parts. Moreover, its material usage rate is high and the production cycle is short. Therefore, AM is the focus of civil aviation and defense industries, which need high-hardness metal materials and precision machining. However, the thermal history of the AM process affects the geometry of the weld pool, causing the workpiece to fail to meet tolerance requirements. Additionally, large temperature gradients and cooling rate inhomogeneity can also lead to excessive residual stress in the formed parts, which may cause deformation or even fracture of the parts. Factors such as poor dimensional and geometric precision, lower surface quality than that in conventionally formed parts, and poor uniformity of material properties hinder further application of AM. To solve the above problems, the concept of additive and subtractive hybrid manufacturing (ASHM) was developed. Additive and subtractive hybrid manufacturing combines AM with traditional machining and material reduction technology on a single work platform. It involves alternating additive and material reduction operations to improve the surface quality and the geometric and dimensional accuracy of the parts and alleviate residual stress in the parts. According to the different characteristics of an energy source for AM, this paper expounded the technical principle and research progress of ASHM based on arc, laser, and other energy sources and introduced the research progress of the ASHM process. The advantages and disadvantages of the application of this technology in the industrial field were analyzed, and the future development direction of the technology was presented. The ASHM process is expected to become more intelligent, integrated, and standardized in the future.
Abstract: Carbon steels are prone to a high level of corrosion when exposed to harsh environments. Stainless steels, having better corrosion resistance, are therefore, used in many applications to mitigate the high risk of failure due to corrosion. However, stainless steels are also not 100% corrosion-resistant; hence, they may suffer uniform corrosion, pitting corrosion, and/or corrosion cracking. It is, therefore, necessary to evaluate the corrosion resistance of stainless steel prior to its large-scale applications. The two main techniques used in studying the corrosion behavior of stainless steels are the immersion and electrochemical tests. Due to the high corrosion resistance of stainless steels, analyzing its corrosion behavior using the immersion test method takes a long period. Consequently, the application of the immersion test method is highly limited. The electrochemical methods are, therefore, widely used due to its faster rate of evaluation of corrosion behavior and mechanisms. The most commonly used electrochemical methods in the corrosion assessment of stainless steels include the corrosion potential test, AC impedance test, potentiostatic test, and cyclic polarization test. This paper introduced these four electrochemical methods of corrosion evaluation of stainless steels. The advantages and disadvantages of various detection methods were also clarified. Long-period corrosion monitoring can be achieved with the implementation of corrosion potential and AC impedance methods, due to their nondestructive features. The polarization characteristic parameters of materials can be obtained by analyzing the potentiostatic or potentiodynamic polarization results. These help to evaluate the corrosion resistance of materials. Comprehensive utilization of various electrochemical methods is beneficial to the analysis of corrosion mechanisms. Given the current research status and trend of corrosion in stainless steel, the electrochemical method is projected to be mainly implemented in the control of the corrosion processes. Therefore, there is need for better detection technologies to achieve a better analysis of the corrosion processes of stainless steels.
Abstract: “Big data” is always collected from different resources that have different data structures. With the rapid development of information technologies, current precious data resources are characteristic of multimodes. As a result, based on classical machine learning strategies, multi-modal learning has become a valuable research topic, enabling computers to process and understand “big data”. The cognitive processes of humans involve perception through different sense organs. Signals from eyes, ears, the nose, and hands (tactile sense) constitute a person’s understanding of a special scene or the world as a whole. It reasonable to believe that multi-modal methods involving a higher ability to process complex heterogeneous data can further promote the progress of information technologies. The concepts of multimodality stemmed from psychology and pedagogy from hundreds of years ago and have been popular in computer science during the past decade. In contrast to the concept of “media”, a “mode” is a more fine-grained concept that is associated with a typical data source or data form. The effective utilization of multi-modal data can aid a computer understand a specific environment in a more holistic way. In this context, we first introduced the definition and main tasks of multi-modal learning. Based on this information, the mechanism and origin of multi-modal machine learning were then briefly introduced. Subsequently, statistical learning methods and deep learning methods for multi-modal tasks were comprehensively summarized. We also introduced the main styles of data fusion in multi-modal perception tasks, including feature representation, shared mapping, and co-training. Additionally, novel adversarial learning strategies for cross-modal matching or generation were reviewed. The main methods for multi-modal learning were outlined in this paper with a focus on future research issues in this field.
Abstract: Given its good physical and mechanical properties and chemical stability, salt rock is considered to be the ideal rock mass for underground reservoir construction. To safeguard China’s energy security and strategic needs, a large number of underground salt cave reservoirs have been built in recent years. In view of the accidents caused by the instability of gas storage in foreign countries, the physical and mechanical properties of salt rock need to be investigated in depth to ensure the long-term stability of salt caverns. The damage-healing characteristics of salt rock have an important influence on the long-term airtightness of underground salt caverns. To examine the healing properties of damaged salt rock, a self-healing experiment was conducted on Brazilian cracked salt rock. Under the no-stress condition, the Brazilian cracked salt rock was healed under different humidity conditions for 120 days. The change in the permeability of the sample was quantitatively evaluated, and the damage-healing characteristics of salt rock under different humidity conditions and healing times were examined. In addition, the microscopic morphology of the damaged salt rock after healing was observed through scanning electron microscopy, and the mesoscopic mechanism of salt rock damage healing was discussed. In this experiment, the change in the permeability of the sample before and after the experiment was used to characterize salt rock damage, which effectively avoided the unreliable results obtained in previous studies through strain hardening, where the strength and elastic moduli of the samples were used to assess damage healing. The experimental results show that, under the no-stress condition, the specimens placed in the environment without external water supply are not healed after 120 days, which proves that water is a necessary condition for wound healing. Previous studies have shown that time and humidity have an important influence on salt rock damage healing. The damage-healing effect on salt rock increases with time and humidity. However, the rate of increase decreases exponentially, which indicates that excessive humidity and time do not effectively improve the damage-healing effect on salt rock.
Abstract: Nowadays, the high-grade manganese ore resources available in the world are run out gradually, while the demand for manganese is increasing; therefore, it is of great significance to research how to exploit and utilize abundant low-grade manganese ore resources economically and effectively. Aiming at the low-grade manganese ore in Indonesia, the process of beneficiating manganese ore by hydrochloric acid leaching and high-value regeneration of acid medium was proposed in this paper. Process mineralogy analyses were performed using X-ray diffraction, optical microscopy, and electron microscopy. The results show that the mineral composition mainly contains calcite and pyrolusite, followed by a small amount of pyrolusite, limonite, and kaolinite. The results of sieve analyses demonstrate that the manganese content in the manganese ore increases with the decrease of particle size. After coarse crushing, manganese middlings with manganese content of 33.32% (mass fraction) can be obtained by screening at 2 mm. The optimum conditions for leaching manganese middlings directly by hydrochloric acid are as follows: leaching pH is 3.0, leaching time is 1.5 h, rotating speed of agitator is 200 r·min?1, and liquid-solid ratio is 4∶1 mL·g?1. The grade of manganese concentrates obtained under the optimum conditions is 54.50% (mass fraction), and the calcium content is 0.57% (mass fraction). Dihydrate gypsum whiskers can be produced by the regeneration of hydrochloric acid at a common temperature, and the length-diameter ratio can be over 50. The regenerated hydrochloric acid is returned to leach manganese middlings. The grade of manganese concentrate and calcium content are 52.16% and 1.39% (mass fraction), which verifies the feasibility of this technological process. The X-ray diffraction (XRD) and scanning electron microscopy (SEM)/energy dispersive X-ray spectroscopy (EDS) results show that the main component of the manganese concentrate is pyrolusite, and the impurities are a small amount of limonite and kaolinite. Impurities will accumulate gradually as acid medium circulates, and they can be removed by hydrolysis precipitation method when Mg2+ concentration accumulates to 96.74 g·L?1.
Abstract: Generally, the flotation performance of mineral particles in a wide size range is usually poor, which can be attributed to the high reagent consumptions and low floatability differences between valuable and gangue minerals. Classification flotation is an effective method for improving the flotation efficiency of particles in a wide size range and is commonly used for coal slime. However, for refractory iron ores, the literature on the relative technology and basic theory of classification flotation, which are necessary and beneficial for the effective utilization of refractory iron ore resources, is scarce. In this study, flotation tests, DLVO theory calculations, and focused beam reflectance measurement (FBRM) particle size analysis were used to analyze the effect of particle size distribution on the flotation separation of hematite and quartz in the sodium oleate system. The flotation results of artificial mixtures show that the flotation performance of coarse or medium hematite–quartz mixture (such as CH&CQ and MH&CQ) with a narrow size range is better than that of the wide size range mixtures. The separation efficiency of CH&CQ and MH&CQ is 85.49% and 84.26%, respectively, which is higher than that of the wide size range mixtures (74.94%). However, the separation efficiency of fine hematite–quartz mixture with a narrow size range (FH&FQ) decreases to 54.98%. The flotation kinetic tests demonstrate that the flotation rate and recovery of hematite are not only related to the particle size of hematite but also influenced by the particle size of quartz. The fine quartz particles could reduce the hematite flotation rate and recovery. The DLVO theory calculations demonstrate that the interaction energies between hematite and quartz are repulsive, indicating that fine quartz particles scarcely cover the hematite surface to depress floatability, which is consistent with the FBRM results. The bubble–particle collision analysis indicates that the collision between hematite and bubbles might be influenced by the “boundary layer” effects of fine quartz particles, resulting in the decreased bubble–particle efficiency of collision and attachment, which may explain the decrease in hematite flotation rate and recovery.
Abstract: Good gas permeability is an essential factor for the smooth operation and high performance in the lower part of the blast furnace. Under the present low carbon blast furnace smelting conditions, the coke layer is thinner, and the proportion of the molten metal in the coke layer is significantly higher, resulting in a major reduction in gas permeability, which seriously affects blast furnace operations. Also, the lower thickness of the coke layer weakens the process of solid-liquid carbon dissolution when the molten iron passes through the coke layer, which reduces the carbon content of the molten iron and further deepens the erosion of the refractory by the unsaturated molten iron. The carbon dissolution in the molten iron in a blast furnace core was measured by a high-temperature vacuum wettability test tool that analyzed the interface wetting activity between Fe?C melts with specific carbon mass fraction (3.8%, 4.3%, 4.8%) and 99.9% of high temperatures graphite plates. Besides, the scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) were used to analyze the graphite substrate’s carburizing morphology and carburizing distances. The results show that, with the increase of carbon content, the interface contact angle becomes bigger. The contact angle decreases with time, and eventually reaches a steady-state during the melting process, and the Fe?C melt with saturated carbon cannot be wet. The scanning electron microscopy analysis shows that a spherical cap-like depression is created by a cross-section of the Fe?C melt and the graphite substrate, and the radius and volume of the depression decrease with increasing carbon content. The study of the EDS scanning analysis shows that the amount of dissolved carbon atoms in the graphite substrate penetrates the Fe?C melt and decreases with increasing initial carbon concentration. The smaller the carburizing effect, the better the wetting is conducive to carbon mass transfer. It is found that by measuring carburizing of the carbon atoms in the graphite substrate into the Fe?C melt by calculating the surface energy reduces the surface energy between the two. Thus, the surface tension decreases and the melt spreads slowly with contact angle gradually decreasing during melting.
Abstract: 4Cr5MoSiV1 hot-die steel exhibits excellent thermal fatigue and comprehensive mechanical properties, and it is widely used in hot forging die and hot extrusion die. Under actual service conditions, mold cavity temperature reaches 700 ℃ during mold operation. Mold cavity surface produces tension and compression strain owing to acute heat and cooling-constraints of subsurface layer, thereby resulting in local plastic deformation of mold and low-cycle fatigue. Therefore, low-cycle fatigue behavior of 4Cr5MoSiV1 steel at 700 ℃ is studied to provide reference data for component design and life prediction of 4Cr5MoSiV1 steel. The effect of total strain amplitude on low-cycle fatigue behavior of 4Cr5MoSiV1 steel at 700 °C has not been studied. The influence of total strain amplitude on the low-cycle fatigue behavior of 4Cr5MoSiV1 steel at 700 ℃ was studied using the low-cycle fatigue test with an axial strain amplitude control, including cyclic stress-response behavior, cyclic stress-strain behavior, cyclic hysteresis loop, and strain-fatigue life behavior. Results show that, with the increase of the total strain amplitude from 0.2% to 0.6%, the cyclic stress responses of 4Cr5MoSiV1 steel at 700 ℃ show the characteristics of cyclic hardening and recycling softening, and the maximum stress amplitude increases from 220 MPa to 308 MPa. As the total strain amplitude increases, the low-cycle fatigue life of 4Cr5MoSiV1 steel at 700 ℃ decreases from 6750 cycles to 210 cycles, and its transition life is approximately 1313 cycles. The results of fatigue fracture morphology analysis show that the crack mainly occurs on the surface of the sample during the high-temperature low-cycle fatigue. With the increase in the strain amplitude, the crack source gradually increases, the distance between fatigue stripes widens, and the fracture mode changes from ductile to brittle fracture. The results of TEM analysis show that the cyclic softening may be related to the change of lath structure to cellular structure, dislocation annihilation of matrix, carbide precipitation, and coarsening.
Abstract: Addition of Sc is capable of greatly improving the mechanical properties of aluminum alloy welded joints, reducing the hot crack sensitivity coefficient; thus, it could solve the welding problem of ultra-high strength aluminum alloys. Friction stir welding has the advantages of small heat-affected zone, low residual stress, and small deformation of welding work piece, making it a good choice for welding materials with high heat crack sensitivity. In this article, the microstructure and properties of friction stir welding (FSW) joints of Al–Zn–Mg–Cu–Zr–(Sc) alloys were characterized via optical microscopy (OM), transmission electron microscopy (TEM), micro-hardness testing, and universal tensile testing. The mechanism of the effect of adding Sc element on improving the welding properties of the ultra-high strength Al–Zn–Mg–Cu–Zr alloy was explored. The results show that the welding joints of Al–Zn–Mg–Cu–Zr–(Sc) alloy exhibit similar microstructure characteristics. The welding nugget zone (WNZ) displays a dynamic recrystallization feature comprising fine and uniform equiaxed grains with high density dislocations. Most of the aged precipitates dissolve into the matrix in the WNZ. The grains in the thermal-mechanical affected zone (TMAZ) are elongated with higher dislocation density, and residual aged precipitates coarsened remarkably. The heat-affected zone (HAZ) retains the same grain morphology as the base metal. Most of the aged η' precipitates grow, and a few coarsen to be the η phase in this zone. However, 0.17% (mass fraction) Sc addition increases the ultimate tensile strength of FSW joint by 43 MPa, yield strength by 23 MPa, elongation by 2.3%, and the welding coefficient up to 74.1%. Al3(Sc, Zr) dispersoids are found to achieve the following: 1) strongly inhibit the movement of dislocations, sub-grain boundaries, and grain boundaries; 2) significantly refine grains while retaining several sub-structures; and 3) factor in Orowan precipitation strengthening. Therefore, the mechanical properties of FSW joints can be improved using the refined grain, sub-structure, and precipitation strengthening mechanisms.
Abstract: Magnesium/aluminum (Mg/Al) bimetallic laminated composites have attracted considerable attention because of their excellent properties. Mg alloys are lightweight structural metals with low density and excellent properties such as high stiffness-to-weight ratio, high strength-to-weight ratio, and good damping capacity. Thus, Mg alloys have considerable potential in automotive and aerospace fields. However, the application of Mg and its alloys is still restricted because of their low corrosion resistance. By contrast, as structural materials, Al alloys are widely used in mechanical and aerospace fields because of their excellent properties, such as light weight, high corrosion resistance, low cost, and good plastic formability. Therefore, Mg/Al laminated composites that combine the advantages of substrates to achieve appropriate coordination, have attracted worldwide attention. To analyze the variation of the bonding strength of hot-rolled Al/Mg clad sheets, various rolling parameters, such as reduction ratio, rolling temperature, and rolling speed, were comprehensively considered in this work. Moreover, 7075 Al/AZ31B Mg composite plates were prepared by single-pass hot rolling. Results show that dynamic recrystallization occurs in the microstructure of the Mg matrix during the rolling process because of heat and strong deformation. Furthermore, the increase in the rolling speed contributed to the complete dynamic recrystallization. At the same rolling temperature, the bonding strength of the Al/Mg composite plates first increased and then decreased with the increase in the reduction ratio. The bonding strength increased because of the increase in the element diffusion width across the interface and the grain refinement near the Mg interface. The bonding strength decreased because cracks occurred near the interface of the Mg matrix due to the strong deformation and excess heat generated by the plastic work, resulting in the growth of the Mg side grains with the increase in the temperature of the Mg matrix. The shear test was conducted on the composite plates. When the shear strength of the Al/Mg composite plates was low, shear fracture occurred at the interface with brittle fracture feature. Although the fracture morphology presented a ductile fracture feature with high shear strength, the fracture occurred on the Mg alloy side.
Abstract: The utilization of high-value-added metallurgical solid waste, such as the use of an inexpensive specialty-steel slag as a rubber functional filler, is an important sustainable development strategy. In this study, we prepared specialty-steel slag-based rubber composites from specialty-steel slag, carbon black, an accelerator, sulfur, zinc oxide, stearic acid, and compound rubber. Then we conducted tests to determine the internal exposure index, external exposure index, stability, tensile strength, tear strength, elongation at break, shore A hardness, limiting oxygen index, burnout time, leaching concentration of heavy metals, mineral composition, particle size distribution, heat conductivity coefficient, pore structure, chemical composition, microstructure, and thermal stability of the composites. We also studied the feasibility and environmental risk associated with using specialty-steel slag as a rubber functional filler. The results show that the mineral composition of the specialty-steel slag includes Ca2SiO4, Ca3Al6Si2O16, (Fe, Mn)2SiO4, Ca3Al2(SiO4)3, Na2TiSiO5, CuMn6SiO12, Na2SiO5, Pb3Ta2O8, Pb3SiO7, and other solid metal melts. This slag also has a good particle size distribution, and its safety and stability meet the requirements of relevant national standards. When the content of the specialty-steel slag in specialty-steel slag-based rubber composites ranges between 20%–40%, these composites have a tensile strength ranging from 20.0–21.5 MPa, a tear strength of 45.2–48.6 kN·m?1, an elongation at break value of 475%–501%, a shore A hardness of 63.5–65.3, a limiting oxygen index of 18.5–18.6, a burnout time of 264–292 s, and a heat conductivity coefficient of 0.15–0.17 W·m?1·K?1. The main heavy-metal oxides in the specialty-steel slag are identified as Cr2O3, PbO, and CuO, which mainly exist as stable solid metals. In addition, the leaching concentration of the heavy metals, such as Cu, Zn, Cd, Pb, Cr, Ba, Ni, and As, from the specialty-steel slag-based rubber composites is much lower than the limit value of the hazardous-waste identification standards. Therefore, specialty-steel slag is safe and feasible for use as a rubber functional filler.
Abstract: Against the background of the widespread application of various electronic devices and communication technologies, there is great concern regarding the problem of excessive radiation of electromagnetic waves with regard to electromagnetic interference, environmental pollution, and human health. Microwave-absorbing materials (MAMs) can transform electromagnetic energy into heat or dissipate electromagnetic waves via interference. Numerous theoretical and experimental studies have focused on the prevention of electromagnetic pollution and other related problems. Magnetite (Fe3O4) is considered one of the most promising MAMs because of its excellent properties, such as high saturation magnetization, high Curie temperature, and low cost. However, the single Fe3O4 has the disadvantages of weak dielectric loss and easy oxidation, thereby limiting its application in the field of microwave absorption. Fabrication of Fe3O4-based nanocomposites is an effective solution for these problems. In this study, a new type of Fe3O4@SnO2 composite similar to myrica rubra (Chinese bayberry) was synthesized by the St?ber method and hydrothermal method using magnetic Fe3O4 microspheres as template. The phase structure, surface elements, micromorphology, magnetic properties, and microwave absorption properties of the samples were characterized by means of X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, and transmission electron microscopy and by observations based on a vibrating-sample magnetometer and vector network analyzer. The results show that the diameter of the myrica rubra-like Fe3O4@SnO2 sphere is about 500 nm, without obvious agglomeration, and that it has good morphological uniformity. The SnO2 layer is composed of nano-SnO2 particles, which are loosely stacked. The layer possesses many porous structures and is about 40 nm thick. The myrica rubra-like Fe3O4@SnO2 has strong dielectric loss capacity, is conducive to improving impedance matching performance, and exhibits good electromagnetic wave absorption capacity. When the thickness is 1.4–2.8 mm, RL(min) exceeds ?20 dB. The optimum thickness is 1.7 mm, RL(min) is ?29 dB, and the effective bandwidth is 4.9 GHz (13.1–18 GHz). It is a potential-absorbing material.
Abstract: To avoid the frequent cross supply, excessive waiting time and difficult crane dispatching of molten steel among processes that resulted from the complex workshop layout of the steelmaking continuous casting process, a production scheduling model for the steelmaking-continuous casting process was established in this study with the objective of optimizing and minimizing the total waiting time of all furnaces in the plan. Moreover, an improved genetic algorithm was used to solve the model. In the operation process of the genetic algorithm, the “furnace-caster coordinating” strategy was introduced to improve the quality of the initial population. Furthermore, the crossover and mutation operations were determined based on the comparison of the operating cycles of steelmaking (refining) and continuous casting. The actual production plan under the main production mode of a large domestic steel plant was utilized as the simulation sample. Results show that the performance of the improved algorithm based on the “furnace-caster coordinating” strategy is significantly better than that of the basic genetic and heuristic algorithms. The output of Sample 1 of the main production model 4BOF?3CCM accounts for more than 80% in steel plants. After optimization, the waiting time of the production process is optimized, and the maximum waiting time between steelmaking and continuous casting processes is reduced from 77 to 54 min. The degree of matching of the refining furnace-continuous caster machine is significantly improved. Moreover, the proportion of molten steel poured from the No. 3 refining furnace on the No. 3 continuous caster machine is increased from 25% to 67%. The phenomenon of unclear matching among processes and facilities caused by random facility assignment for one or two furnaces is reduced. Furthermore, the phenomenon of excessive waiting time caused by unreasonable production path for one or two furnaces is reduced. An efficient solution for the study of complex production scheduling problems in steel plants is provided.
Abstract: Applying a steep pulse voltage of appropriate amplitude to a cell membrane can induce transient and reversible breakdown of the membrane, which has broad application prospects in biomedicine and clinical fields. However, the noise generated by the steep pulse seriously interferes with a patient’s electrocardiogram (ECG) signal resulting in decrease in the accuracy of the ECG feature point detection algorithm. Thus, doctors are unable to understand the state of the patient during treatment, thus limiting complete benefits of the therapy. To eliminate the interference caused by the steep pulse, we analyzed the characteristics of steep pulse interference and established the mathematical model of steep pulse noise. Moreover, we proposed an ECG signal filtering algorithm based on variational mode decomposition (VMD) to extract the steep pulse interference component superimposed on the ECG signal. The proposed algorithm could identify and eliminate the steep pulse interference component. We also designed an ECG signal preprocessing algorithm to reduce the decomposition layer of the VMD algorithm, which improved the real-time performance and reduced the memory consumption. To identify the random noise in the medical environment accompanied by the occurrence of steep pulses, we analyzed the characteristics of random noise in the sub-signal after VMD. Further, we proposed a threshold denoising algorithm based on VMD for sub-signal energy estimation. On the basis of the characteristics of a band-pass filter bank with VMD, we proposed a QRS complex detection algorithm based on VMD sub-signal recombination. Combined with the filtering algorithm, the proposed algorithm was able to improve the accuracy of ECG signal detection. By conducting experiments on ECG signals from the MIT–BIH database with Gaussian white noise and simulated steep pulse interference and those collected in the medical environment, we compared and analyzed the filtering algorithm and QRS complex detection algorithm.
Monthly, started in 1955 Supervising institution：Ministry of Education Sponsoring Institution：University of Science and Technology Beijing Editorial office：Editorial Department of Chinese Journal of Engineering Publisher：Science Press Chairperson：Ren-shu Yang Editor-in-Chief：Ai-xiang Wu ISSN 2095-9389CN 2095-9389
