This paper presents a recognition system for the automatic quality control in industrial applications. The purpose of the system is to collect the product information (e.g. expiry-date, production identification) and ...This paper presents a recognition system for the automatic quality control in industrial applications. The purpose of the system is to collect the product information (e.g. expiry-date, production identification) and verify these information for quality control. The main difficulties of the system are to make an effcient preprocessing for the acquired low resolution image and to create a simple and fast recognition method to get the product information. In this paper, we propose an effcient recognition method based on the endpoint features and structure characteristics of the numerals. The experimental results show that the proposed method is effcient, robust and reliable for recognizing machine printed numerals. The system is currently successfully working with a real application with required specifications.展开更多
A negative Poisson's ratio(NPR)structure represents optimal impact-resistance with applications in various fields,including the crash box in vehicles,which absorbs impact kinetic energy.The crash box is designed t...A negative Poisson's ratio(NPR)structure represents optimal impact-resistance with applications in various fields,including the crash box in vehicles,which absorbs impact kinetic energy.The crash box is designed to deform in response to impact,increasing local structural density,which enhances impact resistance performance.Current studies have only focused on the NPR effect in the plane dimension at low-speed loads.Few studies have considered high-speed impact loads on three-dimensional NPR structures.We have developed two types of AlSi10Mg alloy energy-absorbing structures with NPR using three-dimensional printing technology,and have compared our systems with a conventional hexagonal mesh structure.Sample testing involved split-Hopkinson pressure bar measurements,which showed good agreement with dynamic numerical simulations.When subjected to an impact load,the NPR structure exhibited better impact resistance and energy absorption compared with the positive Poisson's ratio structure.The proposed dual-layer hexagonal structure ensures an NPR effect while exhibiting higher strength and improved stability relative to the conventional concave hexagon structure.展开更多
This review aims to discuss the application and development of three-dimensional printing(3DP) technology in the field of rock mechanics and the mechanical behaviors of 3D-printed specimens on the basis of various ava...This review aims to discuss the application and development of three-dimensional printing(3DP) technology in the field of rock mechanics and the mechanical behaviors of 3D-printed specimens on the basis of various available printing materials.This review begins with a brief description of the concepts and principles associated with 3DP, and then systematically elaborates the five major applications of 3DP technology in the field of rock mechanics, namely, the preparation of rock(including pre-flawed rock) specimens, preparation of joints, preparation of geophysical models, reconstruction of complex rock structures, and performance of bridging experimental testing and numerical simulation.Meanwhile, the mechanical performance of 3D-printed specimens created using six different printing materials, such as polymers, resin,gypsum, sand, ceramics, and rock-like geological materials, is reviewed in detail.Subsequently, some improvements that can make these 3D-printed specimens close to natural rocks and some limitations of 3DP technology in the application of rock mechanics are discussed.Some prospects that are required to be investigated in the future are also proposed.Finally, a brief summary is presented.This review suggests that 3DP technology, especially when integrated with other advanced technologies, such as computed tomography scanning and 3D scanning, has great potential in rock mechanics field.展开更多
With the deepening of human research on deep space exploration,our research on the soft landing methods of landers has gradually deepened.Adding a buffer and energy-absorbing structure to the leg structure of the land...With the deepening of human research on deep space exploration,our research on the soft landing methods of landers has gradually deepened.Adding a buffer and energy-absorbing structure to the leg structure of the lander has become an effective design solution.Based on the energy-absorbing structure of the leg of the interstellar lander,this paper studies the appearance characteristics of the predatory feet of the Odontodactylus scyllarus.The predatory feet of the Odontodactylus scyllarus can not only hit the prey highly when preying,but also can easily withstand the huge counter-impact force.The predatory feet structure of the Odontodactylus scyllarus,like a symmetrical cone,shows excellent rigidity and energy absorption capacity.Inspired by this discovery,we used SLM technology to design and manufacture two nickel-titanium samples,which respectively show high elasticity,shape memory,and get better energy absorption capacity.This research provides an effective way to design and manufacture high-mechanical energy-absorbing buffer structures using bionic 3D printing technology and nickel-titanium alloys.展开更多
This study aims to investigate the benefcial efects of surface retaining elements (SREs) on the mechanical behaviors of bolted rock and roadway stability. 3D printing (3DP) technology is utilized to create rock analog...This study aims to investigate the benefcial efects of surface retaining elements (SREs) on the mechanical behaviors of bolted rock and roadway stability. 3D printing (3DP) technology is utilized to create rock analogue prismatic specimens for conducting this investigation. Uniaxial compression tests with acoustic emission (AE) and digital image correlation techniques have been conducted on 3DP specimens bolted with diferent SREs. The results demonstrate that the strength and modulus of elasticity of the bolted specimens show a positive correlation with the area of the SRE;the AE characteristics of the bolted specimens are higher than those of the unbolted specimen, but they decrease with an increase in SRE area, thus further improving the integrity of the bolted specimens. The reinforcement efect of SREs on the surrounding rock of roadways is further analyzed using numerical modelling and feld test. The results provide a better understanding of the role of SREs in rock bolting and the optimization of rock bolting design. Furthermore, they verify the feasibility of 3DP for rock analogues in rock mechanics tests.展开更多
The hook formation mechanism in continuously cast slabs of ultra-low carbon steel was analyzed in detail through numerical calculations and experimental observations using optical microscopy,and its distribution chara...The hook formation mechanism in continuously cast slabs of ultra-low carbon steel was analyzed in detail through numerical calculations and experimental observations using optical microscopy,and its distribution characteristics were determined.Numerical simulations confirmed that the freezing–overflow mechanism is the primary cause of hook formation.They also revealed that the freezing event occurs unpredictably,while the overflow event takes place during the positive strip time.The average pitch of oscillation marks(OMs)on the slab surface was 8.693 mm,while the theoretical pitch was 8.889 mm,with a difference of approximately 2%.This discrepancy primarily results from varying degrees of overflow,which affects the morphology of the OMs and the positions of their deepest points.Notably,this result further confirmed that the freezing and overflow in the meniscus were indeed caused by the periodic oscillation of the mold.Higher superheat hindered hook formation,leading to a negative correlation between the hook depth distribution around the slab and the temperature distribution within the mold.Therefore,the depth of the corner hook was greater than that of other positions,which was caused by the intensified cooling effect of the corner.Moreover,key factors influencing hook development were analyzed,providing insights into transient fluid flow and heat transfer characteristics within the mold.Transient fluid flow and heat transfer contributed to the randomness and tendency of hook formation.This randomness was reflected in the varying angles of the hooks,whereas the tendency was evident in the negative correlation between superheat and hook length.Based on the randomness and tendency of hook formation and its profile characteristics,a new method for controlling hook depth based on“sine law”is proposed.展开更多
文摘This paper presents a recognition system for the automatic quality control in industrial applications. The purpose of the system is to collect the product information (e.g. expiry-date, production identification) and verify these information for quality control. The main difficulties of the system are to make an effcient preprocessing for the acquired low resolution image and to create a simple and fast recognition method to get the product information. In this paper, we propose an effcient recognition method based on the endpoint features and structure characteristics of the numerals. The experimental results show that the proposed method is effcient, robust and reliable for recognizing machine printed numerals. The system is currently successfully working with a real application with required specifications.
基金This work was funded by the Graduate Innovation Program of China University of Mining and Technology(No.2022WLKXJ053)。
文摘A negative Poisson's ratio(NPR)structure represents optimal impact-resistance with applications in various fields,including the crash box in vehicles,which absorbs impact kinetic energy.The crash box is designed to deform in response to impact,increasing local structural density,which enhances impact resistance performance.Current studies have only focused on the NPR effect in the plane dimension at low-speed loads.Few studies have considered high-speed impact loads on three-dimensional NPR structures.We have developed two types of AlSi10Mg alloy energy-absorbing structures with NPR using three-dimensional printing technology,and have compared our systems with a conventional hexagonal mesh structure.Sample testing involved split-Hopkinson pressure bar measurements,which showed good agreement with dynamic numerical simulations.When subjected to an impact load,the NPR structure exhibited better impact resistance and energy absorption compared with the positive Poisson's ratio structure.The proposed dual-layer hexagonal structure ensures an NPR effect while exhibiting higher strength and improved stability relative to the conventional concave hexagon structure.
基金financially supported by the Fundamental Research Funds for the Central Universities (No.FRF-TP18-016A3)the National Natural Science Foundation of China (No.51504016)。
文摘This review aims to discuss the application and development of three-dimensional printing(3DP) technology in the field of rock mechanics and the mechanical behaviors of 3D-printed specimens on the basis of various available printing materials.This review begins with a brief description of the concepts and principles associated with 3DP, and then systematically elaborates the five major applications of 3DP technology in the field of rock mechanics, namely, the preparation of rock(including pre-flawed rock) specimens, preparation of joints, preparation of geophysical models, reconstruction of complex rock structures, and performance of bridging experimental testing and numerical simulation.Meanwhile, the mechanical performance of 3D-printed specimens created using six different printing materials, such as polymers, resin,gypsum, sand, ceramics, and rock-like geological materials, is reviewed in detail.Subsequently, some improvements that can make these 3D-printed specimens close to natural rocks and some limitations of 3DP technology in the application of rock mechanics are discussed.Some prospects that are required to be investigated in the future are also proposed.Finally, a brief summary is presented.This review suggests that 3DP technology, especially when integrated with other advanced technologies, such as computed tomography scanning and 3D scanning, has great potential in rock mechanics field.
基金Supported by National Key R&D Program of China(Grant No.2022YFE0138500)National Natural Science Foundation of China(Grant No.51975246)+2 种基金Science and Technology Development Program of Jilin Province of China(Grant No.20220101192JC)Capital Construction Fund Plan within the Budget of Jilin Province of China(Grant No.2023C041-4)Chongqing Municipal Natural Science Foundation of China(Grant No.CSTB2022NSCQ-MSX0225).
文摘With the deepening of human research on deep space exploration,our research on the soft landing methods of landers has gradually deepened.Adding a buffer and energy-absorbing structure to the leg structure of the lander has become an effective design solution.Based on the energy-absorbing structure of the leg of the interstellar lander,this paper studies the appearance characteristics of the predatory feet of the Odontodactylus scyllarus.The predatory feet of the Odontodactylus scyllarus can not only hit the prey highly when preying,but also can easily withstand the huge counter-impact force.The predatory feet structure of the Odontodactylus scyllarus,like a symmetrical cone,shows excellent rigidity and energy absorption capacity.Inspired by this discovery,we used SLM technology to design and manufacture two nickel-titanium samples,which respectively show high elasticity,shape memory,and get better energy absorption capacity.This research provides an effective way to design and manufacture high-mechanical energy-absorbing buffer structures using bionic 3D printing technology and nickel-titanium alloys.
基金supported by the Young Scientist Project of National Key Research and Development Program of China(2021YFC2900600)the National Natural Science Foundation of China(52074166)Shandong Province(ZR2021YQ38).
文摘This study aims to investigate the benefcial efects of surface retaining elements (SREs) on the mechanical behaviors of bolted rock and roadway stability. 3D printing (3DP) technology is utilized to create rock analogue prismatic specimens for conducting this investigation. Uniaxial compression tests with acoustic emission (AE) and digital image correlation techniques have been conducted on 3DP specimens bolted with diferent SREs. The results demonstrate that the strength and modulus of elasticity of the bolted specimens show a positive correlation with the area of the SRE;the AE characteristics of the bolted specimens are higher than those of the unbolted specimen, but they decrease with an increase in SRE area, thus further improving the integrity of the bolted specimens. The reinforcement efect of SREs on the surrounding rock of roadways is further analyzed using numerical modelling and feld test. The results provide a better understanding of the role of SREs in rock bolting and the optimization of rock bolting design. Furthermore, they verify the feasibility of 3DP for rock analogues in rock mechanics tests.
基金financially supported by the National Natural Science Foundation of China(No.52174306)the Fundamental Research Funds for the Central Universities(Nos.N2225023 and N2425006)the Basic Research Projects of Liaoning Provincial Department of Education(No.LJ212410148027)。
文摘The hook formation mechanism in continuously cast slabs of ultra-low carbon steel was analyzed in detail through numerical calculations and experimental observations using optical microscopy,and its distribution characteristics were determined.Numerical simulations confirmed that the freezing–overflow mechanism is the primary cause of hook formation.They also revealed that the freezing event occurs unpredictably,while the overflow event takes place during the positive strip time.The average pitch of oscillation marks(OMs)on the slab surface was 8.693 mm,while the theoretical pitch was 8.889 mm,with a difference of approximately 2%.This discrepancy primarily results from varying degrees of overflow,which affects the morphology of the OMs and the positions of their deepest points.Notably,this result further confirmed that the freezing and overflow in the meniscus were indeed caused by the periodic oscillation of the mold.Higher superheat hindered hook formation,leading to a negative correlation between the hook depth distribution around the slab and the temperature distribution within the mold.Therefore,the depth of the corner hook was greater than that of other positions,which was caused by the intensified cooling effect of the corner.Moreover,key factors influencing hook development were analyzed,providing insights into transient fluid flow and heat transfer characteristics within the mold.Transient fluid flow and heat transfer contributed to the randomness and tendency of hook formation.This randomness was reflected in the varying angles of the hooks,whereas the tendency was evident in the negative correlation between superheat and hook length.Based on the randomness and tendency of hook formation and its profile characteristics,a new method for controlling hook depth based on“sine law”is proposed.
