when a gun fires, a large amount of heat is brought in the barrel. Erosion/wear and security problems(self ignition of the propellant) associated with this high thermal energy have to be solved owing to the use of hig...when a gun fires, a large amount of heat is brought in the barrel. Erosion/wear and security problems(self ignition of the propellant) associated with this high thermal energy have to be solved owing to the use of higher combustion gas temperature for improved cannon performance and firing at the sustained high rates. Barrel cooling technologies are the effective measures for addressing this issue. In view of the importance of having knowledge of the heat flux, an approach to calculate heat flux based on measurements was presented and validated. The calculated heat flux is used as the inner boundary condition for modeling heat transfer in a 155 mm mid-wall cooled compound gun barrel. Theoretical analysis and simulated results show that natural air cooling is dramatically slower than the forced liquid mid-wall cooling, accordingly wear life of actively cooled barrel is increased and barrel overheating is prevented.展开更多
Objective: To systematically explore the effects of moderate-intensity static magnetic fields (SMF) on type 2 diabetic wound healing and preliminarily explore the possible mechanism, and hence to lay a foundation for ...Objective: To systematically explore the effects of moderate-intensity static magnetic fields (SMF) on type 2 diabetic wound healing and preliminarily explore the possible mechanism, and hence to lay a foundation for its scientific and extensive clinical application. Methods:Round-shape wound of soft tissues with 1-cm diameter was constructed on the dorsum of thirty-two 3-month-old male type 2 diabetic db/db mice and sixteen wild-type mice with the same gene background, followed by covered with transparent film wound dressing. The experiment was divided into the control group (control), db/db mice group (db/db), and db/db mice exposed to SMF group (db/db+SMF) with sixteen mice in each group. Four mice in each group were killed post 5, 12 and 19 days of the wound model establishment, respectively. The mice in the db/db+SMF group were subjected to systemic SMF exposure (4 mT peak intensity) with 2 h per day. The wound closure rate, overall wound healing period, tensile strength, and histopathological morphology in each group were determined and analyzed. The interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and vascular endothelial growth factor (VEGF) gene expression were also measured and analyzed. Results: SMF significantly increased the wound closure rate (P<0.05), decreased the overall healing period (P<0.05), increased the tensile strength of wound tissues (P<0.05), decreased the number of inflammatory cells, and inhibited the expression of inflammatory cytokines (IL-1β, TNF-αand IL-6) in db/db mice at 5, 12 and 19 days post-surgery (P<0.05), whereas SMF had no significant effect on the VEGF expression. Conclusion: Moderate-intensity systemic SMF exposure exhibits positive therapeutic effects on accelerating type 2 diabetic soft tissue wound repair, and the positive effects are closely related to its significant anti-inflammatory response.展开更多
Objective:The current study aims to identify the effects of exogenous application of pulsed electromagnetic fields on skin wound healing in diabetic rats, and thus provides experimental evidence for its more scientifi...Objective:The current study aims to identify the effects of exogenous application of pulsed electromagnetic fields on skin wound healing in diabetic rats, and thus provides experimental evidence for its more scientific clinical application in the future.Methods: The diabetic animal models were established via intraperitoneal injection of streptozotocin in 4-month-old male rats. Fourth eight rats were randomly assigned into the diabetes group (DM) and diabetes coupled with pulsed electromagnetic fields (DM+PEMF) group. Another 24 normal rats were used as the blank control group (Control). Then, all the rats in the three groups were subjected to dorsal surgery for the establishment of soft tissue wound model (circular wound with the diameter of 2 cm). Then, the rats in the DM+PEMF group were subjected to pulsed electromagnetic fields stimulation. Then, 6 rats in each group were sacrificed at Day 5, 12 and 19 post surgery. The glucose levels, wound closure, wound healing time and tissue tensile strength were examined and analyzed.Results: Pulsed electromagnetic fields significantly increased the wound closure rate in diabetic rats at Day 5, 12 and 19 post surgery, decreased overall wound healing period in diabetic rats, and also enhanced tissue tensile strength in diabetic rats at Day 5, 12 and 19 post surgery.Conclusion: Low-intensity pulsed electromagnetic fields can significantly accelerate diabetic wound healing process, and also improve diabetic tissue repair capacity. This study may be helpful for providing more scientific and reasonable experimental evidence for the treatment of pulsed electromagnetic fields on diabetic wound healing in clinics.展开更多
A novel surface-repairing technique for gun bore was investigated, which was combined with the merits such as anti-erosion wear, damage-repairing, and etc. It was accomplished by adhering a special rare earth nanocomp...A novel surface-repairing technique for gun bore was investigated, which was combined with the merits such as anti-erosion wear, damage-repairing, and etc. It was accomplished by adhering a special rare earth nanocomposite evenly to the micro-surface of gun bore. The effectiveness of this technique was approved by the target-firing using a domestic automatic rifle with chromium-coated bore. Its characteristics were discussed based on the surface analyses of the rifle bore by secondary ion mass spectrometry(SIMS),scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) analysis.展开更多
The dynamic traveling salesman problem(DTSP)is significant in logistics distribution in real-world applications in smart cities,but it is uncertain and difficult to solve.This paper proposes a scheme library-based ant...The dynamic traveling salesman problem(DTSP)is significant in logistics distribution in real-world applications in smart cities,but it is uncertain and difficult to solve.This paper proposes a scheme library-based ant colony optimization(ACO)with a two-optimization(2-opt)strategy to solve the DTSP efficiently.The work is novel and contributes to three aspects:problemmodel,optimization framework,and algorithmdesign.Firstly,in the problem model,traditional DTSP models often consider the change of travel distance between two nodes over time,while this paper focuses on a special DTSP model in that the node locations change dynamically over time.Secondly,in the optimization framework,the ACO algorithm is carried out in an offline optimization and online application framework to efficiently reuse the historical information to help fast respond to the dynamic environment.The framework of offline optimization and online application is proposed due to the fact that the environmental change inDTSPis caused by the change of node location,and therefore the newenvironment is somehowsimilar to certain previous environments.This way,in the offline optimization,the solutions for possible environmental changes are optimized in advance,and are stored in a mode scheme library.In the online application,when an environmental change is detected,the candidate solutions stored in the mode scheme library are reused via ACO to improve search efficiency and reduce computational complexity.Thirdly,in the algorithm design,the ACO cooperates with the 2-opt strategy to enhance search efficiency.To evaluate the performance of ACO with 2-opt,we design two challenging DTSP cases with up to 200 and 1379 nodes and compare them with other ACO and genetic algorithms.The experimental results show that ACO with 2-opt can solve the DTSPs effectively.展开更多
文摘when a gun fires, a large amount of heat is brought in the barrel. Erosion/wear and security problems(self ignition of the propellant) associated with this high thermal energy have to be solved owing to the use of higher combustion gas temperature for improved cannon performance and firing at the sustained high rates. Barrel cooling technologies are the effective measures for addressing this issue. In view of the importance of having knowledge of the heat flux, an approach to calculate heat flux based on measurements was presented and validated. The calculated heat flux is used as the inner boundary condition for modeling heat transfer in a 155 mm mid-wall cooled compound gun barrel. Theoretical analysis and simulated results show that natural air cooling is dramatically slower than the forced liquid mid-wall cooling, accordingly wear life of actively cooled barrel is increased and barrel overheating is prevented.
基金This study was supported by the General Project of National Natural Science Foundation of China (Grant 81471806)
文摘Objective: To systematically explore the effects of moderate-intensity static magnetic fields (SMF) on type 2 diabetic wound healing and preliminarily explore the possible mechanism, and hence to lay a foundation for its scientific and extensive clinical application. Methods:Round-shape wound of soft tissues with 1-cm diameter was constructed on the dorsum of thirty-two 3-month-old male type 2 diabetic db/db mice and sixteen wild-type mice with the same gene background, followed by covered with transparent film wound dressing. The experiment was divided into the control group (control), db/db mice group (db/db), and db/db mice exposed to SMF group (db/db+SMF) with sixteen mice in each group. Four mice in each group were killed post 5, 12 and 19 days of the wound model establishment, respectively. The mice in the db/db+SMF group were subjected to systemic SMF exposure (4 mT peak intensity) with 2 h per day. The wound closure rate, overall wound healing period, tensile strength, and histopathological morphology in each group were determined and analyzed. The interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and vascular endothelial growth factor (VEGF) gene expression were also measured and analyzed. Results: SMF significantly increased the wound closure rate (P<0.05), decreased the overall healing period (P<0.05), increased the tensile strength of wound tissues (P<0.05), decreased the number of inflammatory cells, and inhibited the expression of inflammatory cytokines (IL-1β, TNF-αand IL-6) in db/db mice at 5, 12 and 19 days post-surgery (P<0.05), whereas SMF had no significant effect on the VEGF expression. Conclusion: Moderate-intensity systemic SMF exposure exhibits positive therapeutic effects on accelerating type 2 diabetic soft tissue wound repair, and the positive effects are closely related to its significant anti-inflammatory response.
基金National Natural Science Foundation of China,No.81471806.
文摘Objective:The current study aims to identify the effects of exogenous application of pulsed electromagnetic fields on skin wound healing in diabetic rats, and thus provides experimental evidence for its more scientific clinical application in the future.Methods: The diabetic animal models were established via intraperitoneal injection of streptozotocin in 4-month-old male rats. Fourth eight rats were randomly assigned into the diabetes group (DM) and diabetes coupled with pulsed electromagnetic fields (DM+PEMF) group. Another 24 normal rats were used as the blank control group (Control). Then, all the rats in the three groups were subjected to dorsal surgery for the establishment of soft tissue wound model (circular wound with the diameter of 2 cm). Then, the rats in the DM+PEMF group were subjected to pulsed electromagnetic fields stimulation. Then, 6 rats in each group were sacrificed at Day 5, 12 and 19 post surgery. The glucose levels, wound closure, wound healing time and tissue tensile strength were examined and analyzed.Results: Pulsed electromagnetic fields significantly increased the wound closure rate in diabetic rats at Day 5, 12 and 19 post surgery, decreased overall wound healing period in diabetic rats, and also enhanced tissue tensile strength in diabetic rats at Day 5, 12 and 19 post surgery.Conclusion: Low-intensity pulsed electromagnetic fields can significantly accelerate diabetic wound healing process, and also improve diabetic tissue repair capacity. This study may be helpful for providing more scientific and reasonable experimental evidence for the treatment of pulsed electromagnetic fields on diabetic wound healing in clinics.
文摘A novel surface-repairing technique for gun bore was investigated, which was combined with the merits such as anti-erosion wear, damage-repairing, and etc. It was accomplished by adhering a special rare earth nanocomposite evenly to the micro-surface of gun bore. The effectiveness of this technique was approved by the target-firing using a domestic automatic rifle with chromium-coated bore. Its characteristics were discussed based on the surface analyses of the rifle bore by secondary ion mass spectrometry(SIMS),scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) analysis.
基金supported in part by the National Research Foundation of Korea (NRF-2021H1D3A2A01082705).
文摘The dynamic traveling salesman problem(DTSP)is significant in logistics distribution in real-world applications in smart cities,but it is uncertain and difficult to solve.This paper proposes a scheme library-based ant colony optimization(ACO)with a two-optimization(2-opt)strategy to solve the DTSP efficiently.The work is novel and contributes to three aspects:problemmodel,optimization framework,and algorithmdesign.Firstly,in the problem model,traditional DTSP models often consider the change of travel distance between two nodes over time,while this paper focuses on a special DTSP model in that the node locations change dynamically over time.Secondly,in the optimization framework,the ACO algorithm is carried out in an offline optimization and online application framework to efficiently reuse the historical information to help fast respond to the dynamic environment.The framework of offline optimization and online application is proposed due to the fact that the environmental change inDTSPis caused by the change of node location,and therefore the newenvironment is somehowsimilar to certain previous environments.This way,in the offline optimization,the solutions for possible environmental changes are optimized in advance,and are stored in a mode scheme library.In the online application,when an environmental change is detected,the candidate solutions stored in the mode scheme library are reused via ACO to improve search efficiency and reduce computational complexity.Thirdly,in the algorithm design,the ACO cooperates with the 2-opt strategy to enhance search efficiency.To evaluate the performance of ACO with 2-opt,we design two challenging DTSP cases with up to 200 and 1379 nodes and compare them with other ACO and genetic algorithms.The experimental results show that ACO with 2-opt can solve the DTSPs effectively.
