The plasma membrane(PM)plays an essential role in maintaining cell homeostasis,therefore,timely and effective repair of damage caused by factors such as mechanical rupture,pore-forming toxins,or pore-forming proteins ...The plasma membrane(PM)plays an essential role in maintaining cell homeostasis,therefore,timely and effective repair of damage caused by factors such as mechanical rupture,pore-forming toxins,or pore-forming proteins is crucial for cell survival.PM damage induces membrane rupture and stimulates an immune response.However,damage resulting from regulated cell death processes,including pyroptosis,ferroptosis,and necroptosis,cannot be repaired by simple sealing mechanisms and thus,requires specialized repair machinery.Recent research has identified a PM repair mechanism of regulated cell death-related injury,mediated by the endosomal sorting complexes required for transport(ESCRT)machinery.Here,we review recent progress in elucidating the ESCRT machinery-mediated repair mechanism of PM injury,with particular focus on processes related to regulated cell death.This overview,along with continued research in this field,may provide novel insights into therapeutic targets for diseases associated with dysregulation of regulated cell death pathways.展开更多
To address the issue of extreme thermal-induced arching in CRTS II slab tracks due to joint damage,an optimized joint repair model was proposed.First,the formula for calculating the safe temperature rise of the track ...To address the issue of extreme thermal-induced arching in CRTS II slab tracks due to joint damage,an optimized joint repair model was proposed.First,the formula for calculating the safe temperature rise of the track was derived based on the principle of stationary potential energy.Considering interlayer evolution and structural crack propagation,an optimized joint repair model for the track was established and validated.Subsequently,the impact of joint repair on track damage and arch stability under extreme temperatures was studied,and a comprehensive evaluation of the feasibility of joint repair and the evolution of damage after repair was conducted.The results show that after the joint repair,the temperature rise of the initial damage of the track structure can be increased by 11℃.Under the most unfavorable heating load with a superimposed temperature gradient,the maximum stiffness degradation index SDEG in the track structure is reduced by about 81.16%following joint repair.The joint repair process could effectively reduce the deformation of the slab arching under high temperatures,resulting in a reduction of 93.96%in upward arching deformation.After repair,with the damage to interfacing shear strength,the track arch increases by 2.616 mm.展开更多
Renewing warranty can provide customers with better service,and thus help manufacturers to gain market opportunities.In engineering practice,the cost for replacement is usually higher than the cost for maintenance,hen...Renewing warranty can provide customers with better service,and thus help manufacturers to gain market opportunities.In engineering practice,the cost for replacement is usually higher than the cost for maintenance,hence manufacturers often face huge challenge to reduce the warranty service cost.With consideration of the warranty deadline,we propose a two-stage optimization model for renewing warranty.In the first stage,a renewing warranty with deadline(RWD)policy is implemented,where the deadline represents the cumulative uptime threshold.When the cumulative uptime exceeds the deadline,the product will be minimally repaired and kept to the residual warranty period.When RWD is expired,the replacement warranty with limited repairs(RWLR)policy is applied.Under the free replacement and pro-rata warranty policy,the corresponding two-stage cost optimization model is established from the manufacturer’s perspective,the aim is to minimize the cost rate and obtain the optimal warranty period.A numerical example is provided to illustrate the validity of the proposed model,and the sensitivity analysis is also carried out.展开更多
This paper deals with a cold standby repairman who can do extra work in idle time. The repairable system with two identical units and one authors are devoted to studying the unique existence and exponential stability ...This paper deals with a cold standby repairman who can do extra work in idle time. The repairable system with two identical units and one authors are devoted to studying the unique existence and exponential stability of the system solution. C0-semigroup theory is used to prove the existence of a unique nonnegative time-dependent solution of the system. Then by using the theory of resolvent positive operator, the authors derive that dynamic solution of the system exponentially converges to its steady-state one which is the eigenfunction corresponding to eigenvalue 0 of the system operator. Some reliability indices of the system are discussed with a different method from traditional one. The authors also make a profit analysis to determine the optimal service time outside the system to maximize the system profit.展开更多
Level of repair analysis（LORA） is an important method of maintenance decision for establishing systems of operation and maintenance in the equipment development period. Currently, the research on equipment of repair...Level of repair analysis（LORA） is an important method of maintenance decision for establishing systems of operation and maintenance in the equipment development period. Currently, the research on equipment of repair level focuses on economic analysis models which are used to optimize costs and rarely considers the maintenance time required by the implementation of the maintenance program. In fact, as to the system requiring high mission complete success, the maintenance time is an important factor which has a great influence on the availability of equipment systems. Considering the relationship between the maintenance time and the spares stocks level, it is obvious that there are contradictions between the maintenance time and the cost. In order to balance these two factors, it is necessary to build an optimization LORA model. To this end, the maintenance time representing performance characteristic is introduced, and on the basis of spares stocks which is traditionally regarded as a decision variable, a decision variable of repair level is added, and a multi-echelon multiindenture（MEMI） optimization LORA model is built which takes the best cost-effectiveness ratio as the criterion, the expected number of backorder（EBO） as the objective function and the cost as the constraint. Besides, the paper designs a convex programming algorithm of multi-variable for the optimization model, provides solutions to the non-convex objective function and methods for improving the efficiency of the algorithm. The method provided in this paper is proved to be credible and effective according to the numerical example and the simulation result.展开更多
An innovative approach to increase structural survivability of concrete and maintain structural durability of concrete was developed in case of earthquakes and typhoons. This approach takes advantage of the superelast...An innovative approach to increase structural survivability of concrete and maintain structural durability of concrete was developed in case of earthquakes and typhoons. This approach takes advantage of the superelastic effect of shape memory alloy(SMA) and the cohering characteristic of repairing adhesive. These SMA wires and brittle fibers containing adhesives were embedded into concrete beams during concrete casting to form smart reinforced concrete beams. The self-repairing capacity of smart concrete beams was investigated by three-point bending tests. The experimental results show that SMA wires add self-restoration capacity,the concrete beams recover almost completely after incurring an extremely large deflection and the cracks are closed almost completely by the recovery forces of SMA wires. The number or areas of SMA wires has no influence on the tendency of deformation during loading and the tendency of reversion by the superelasticity. The adhesives released from the broken-open fibers fill voids and cracks. The repaired damage enables continued function and prevents further degradation.展开更多
Compared with the classical Markov repairable system, the Markov repairable system with stochastic regimes switching introduced in the paper provides a more realistic description of the practical system. The system ca...Compared with the classical Markov repairable system, the Markov repairable system with stochastic regimes switching introduced in the paper provides a more realistic description of the practical system. The system can be used to model the dynamics of a repairable system whose performance regimes switch according to the external conditions. For example, to satisfy the demand variation that is typical for the power and communication systems and reduce the cost, these systems usually adjust their operating regimes. The transition rate matrices under distinct operating regimes are assumed to be different and the sojourn times in distinct regimes are governed by a finite state Markov chain. By using the theory of Markov process, Ion channel theory, and Laplace transforms, the up time of the system are studied. A numerical example is given to illustrate the obtained results. The effect of sojourn times in distinct regimes on the availability and the up time are also discussed in the numerical example.展开更多
The evolution of temperature field of the continual motion induction cladding and the depth of heat affected zone are studied in this study.A three-dimensional finite element model for the point type continual inducti...The evolution of temperature field of the continual motion induction cladding and the depth of heat affected zone are studied in this study.A three-dimensional finite element model for the point type continual induction cladding is established to investigate temperature distributions of fixed and motion induction cladding modes.The novel inductor is designed for cladding of curved surfaces.The modeling reliability is verified by the temperature measurements.The influence of process parameters on the maximum temperature and the generation and transfer of heat are studied.Quantitative calculation is performed to its melting rate to verify the temperature distribution and microstructures.The results show that a good metallurgical bond can be formed between the cladding layer and substrate.The melting rate gradually falls from the top of the cladding layer to the substrate,and the grain size in the substrate gradually rises.The heat affected zone is relatively small compared to integral heating.展开更多
The availability of a periodic inspection system under mixed maintenance policies is studied in this paper.To accommodate the characteristic of multiple failure modes for complex systems,the system failures can be div...The availability of a periodic inspection system under mixed maintenance policies is studied in this paper.To accommodate the characteristic of multiple failure modes for complex systems,the system failures can be divided into two failure modes:hard failure and soft failure.When hard failure occurs,the corresponding corrective maintenance will be performed,taking a random time under the perfect maintenance policy;in contrast,if the soft failure is found,the corresponding preventive maintenance will be performed,taking a random time under the imperfect maintenance policy.The dynamic age setback model is adopted for imperfect maintenance,which can accurately reflect the fault characteristics of the degraded system.Then an analytical model for system steady state availability and instantaneous availability are derived.Moreover,the optimal method to maximize the system steady-state availability through adjusting the inspection interval is researched.According to the above research,the optimization of system unit time cost,preventive maintenance intervals and availability is researched.Finally,the developed approach is demonstrated by a numerical example.展开更多
The reliability of the product sold under a warranty is usually maintained by the manufacturer during the warranty period. After the expiry of the warranty, however, the consumer confronts a problem about how to maint...The reliability of the product sold under a warranty is usually maintained by the manufacturer during the warranty period. After the expiry of the warranty, however, the consumer confronts a problem about how to maintain the reliability of the product. This paper proposes, from the consumer's perspective, a replacement policy after the extended warranty, under the assumption that the product is sold under the renewable free replacement warranty (RFRW) policy in which the replacement is dependent on the repair-cost threshold. The proposed replacement policy is the replacement after the extended warranty is performed by the consumer based on the repair-cost threshold or preventive replacement (PR) age, which are decision variables. The expected cost rate model is derived from the consumer's perspective. The existence and uniqueness of the optimal solution that minimizes the expected cost rate per unit time are offered. Finally, a numerical example is presented to exemplify the proposed model.展开更多
Due to the simplicity and flexibility of the power law process,it is widely used to model the failures of repairable systems.Although statistical inference on the parameters of the power law process has been well deve...Due to the simplicity and flexibility of the power law process,it is widely used to model the failures of repairable systems.Although statistical inference on the parameters of the power law process has been well developed,numerous studies largely depend on complete failure data.A few methods on incomplete data are reported to process such data,but they are limited to their specific cases,especially to that where missing data occur at the early stage of the failures.No framework to handle generic scenarios is available.To overcome this problem,from the point of view of order statistics,the statistical inference of the power law process with incomplete data is established in this paper.The theoretical derivation is carried out and the case studies demonstrate and verify the proposed method.Order statistics offer an alternative to the statistical inference of the power law process with incomplete data as they can reformulate current studies on the left censored failure data and interval censored data in a unified framework.The results show that the proposed method has more flexibility and more applicability.展开更多
The application of mixed powders with different mass fraction on laser additive repairing(LAR)can be an effective way to guarantee the performance and functionality of repaired part in time.A convenient and feasible a...The application of mixed powders with different mass fraction on laser additive repairing(LAR)can be an effective way to guarantee the performance and functionality of repaired part in time.A convenient and feasible approach is presented to repair TA15 forgings by employing Ti6Al4V-xTA15 mixed powders in this paper.The performance compatibility of Ti6Al4V-xTA15 powders from the aspects of microhardness,tensile property,heat capacity,thermal expansion coefficient and corrosion resistance with the TA15 forgings was fully investigated.The primaryαlaths were refined and the volume fraction of the secondaryαphase was increased by increasing the mass fraction of TA15 in the mixed Ti6Al4V-xTA15 powders,leading to varied performances.In conclusion,the mixed Ti6Al4V-70%TA15(x=70%)powders is the most suitable candidate and is recommended as the raw material for LAR of TA15 forgings based on overall consideration of the compatibility calculations of the laser repaired zone with the wrought substrate zone.展开更多
Objective Acute Stanford type A aortic dissection is typically presented as antegrade dissection from a primary intimal tear in the proximal ascending aorta extending to the arch and the downstream distal aorta.Howeve...Objective Acute Stanford type A aortic dissection is typically presented as antegrade dissection from a primary intimal tear in the proximal ascending aorta extending to the arch and the downstream distal aorta.However,it may also develop in a retrograde fashion with an intimal tear located in descending aorta causing retrograde extension of aortic dissection into ascending aorta,namely,retrograde type A aortic dissection(RTAAD).Though open surgery remains the golden standard to treat type A dissection,as to RTAAD,the distal location of its primary entry tear in descending aorta warrants more extensive aortic repair with higher surgical risks of mortality or morbidity through a median sternotomy.Conversely,confining the surgical extent to the proximal aorta leaves the risks of complications related to the residual tear in the distal aorta untreated.More recently,thoracic endovascular aortic repair(TEVAR)is attempted for the treatment of RTAAD with favorable shortterm and long-term prognosis.To the best of our knowledge,this was the largest serial study to apply TEVAR in the treatment of RTAAD.展开更多
Electromagnetic detection satellite（EDS） is a type of Earth observation satellite（EOS）. Satellites observation and data down-link scheduling plays a significant role in improving the efficiency of satellite observ...Electromagnetic detection satellite（EDS） is a type of Earth observation satellite（EOS）. Satellites observation and data down-link scheduling plays a significant role in improving the efficiency of satellite observation systems. However, the current works mainly focus on the scheduling of imaging satellites, little work focuses on the scheduling of EDSes for its specific requirements.And current works mainly schedule satellite resources and data down-link resources separately, not considering them in a globally optimal perspective. The EDSes and data down-link resources are scheduled in an integrated process and the scheduling result is searched globally. Considering the specific constraints of EDS, a coordinate scheduling model for EDS observation tasks and data transmission jobs is established and an algorithm based on the genetic algorithm is proposed. Furthermore, the convergence of our algorithm is proved. To deal with some specific constraints, a solution repairing algorithm of polynomial computing time is designed. Finally, some experiments are conducted to validate the correctness and practicability of our scheduling algorithms.展开更多
Bone marrow derived mesenchymal stem cells(MSCs)have been widely used to promote the repair or regeneration of damaged tissues.In previous studies,we have developed several stem cells based strategies to promote the b...Bone marrow derived mesenchymal stem cells(MSCs)have been widely used to promote the repair or regeneration of damaged tissues.In previous studies,we have developed several stem cells based strategies to promote the bone repair,which includes the BMP-2 gene medicine,construction of tissue engineering bone in bioreactor and clinical trial of enriched stem cell therapy.Among these studies,one challenge is to construct the tissue engineered bone at the large scale which face the problem of poor survivor of seeding cells in the scaffold interior.In our studies,the porousβ-TCP cylindrical scaffolds loading with MSCs were continuously perfused by a customized bioreactor(dynamic culture)at different flow rate or were immersed展开更多
In the past,most hydrogel composites of bone repair derived from either natural or chemical synthesis were lack of mechanical strength.So we used high strengthened PAA-Ch-Si hydrogel compounds and it containing PRP(pl...In the past,most hydrogel composites of bone repair derived from either natural or chemical synthesis were lack of mechanical strength.So we used high strengthened PAA-Ch-Si hydrogel compounds and it containing PRP(platelet-rich-plasma)material.They were prepared by UV light or y-ray irradiation method for scaffold material application in this paper.We exploited nanosized silica solution,natural chitosan and acrylic acid(AAc)as starting material to synthesize chitosan/hydrogel biomedical products.This biocompatible osteoconductive scaffold mixed with platelet glue to perform the biocompatibility tests for a composite bone graft material and be ap-展开更多
The essence of gene therapy is to placefunctioning genes into a patient’s cells for therapeuticpurposes. Gene therapy may be employed to ①enhance anti-tumor immune responses; ②
OBJECTIVE To investigate the role of e IF3a in the regulation of DNA repair pathways in cancer chemotherapeutic response.METHODS Immunohistochemistry was used to determine the expression of e IF3a in lung and breast c...OBJECTIVE To investigate the role of e IF3a in the regulation of DNA repair pathways in cancer chemotherapeutic response.METHODS Immunohistochemistry was used to determine the expression of e IF3a in lung and breast cancer tissues followed by association analysis of e IF3a expression with patient′s response to chemotherapy.Ectopic overexpression and RNA interference knockdown of e IF3a were carried out in NIH3T3and H1299 cell lines,respectively,to determine the effect of altered e IF3a expression on cellular response to chemotherapeutic drugs by using MTT assay.The DNA repair capacity of these cells was evaluated by using host-cell reactivation,NHEJ and HR assay.Real-time reverse transcriptase PCR and Western Blot analyses were carried out to determine the effect of e IF3a on the DNA repair genes by using cells with altered e IF3a expression.RESULTS e IF3a expression associates with response of lung and breast cancer patients to platinum and anthracycline.e IF3a knockdown or overexpression,respectively,increased and decreased the cellular resistance to cisplatin and anthracycline anticancer drugs,DNA repair activity,and expression of NER and NHEJ DNA repair proteins.CONCLUSION e IF3a plays an important role in regulating the expression of NER and NHEJ DNA repair proteins which,in turn,contributes to cellular response to DNA-damaging anticancer drugs and patients′response to platinum and anthracycline chemotherapy.展开更多
Protein Rad23, a nucleotide excision repair factor, mainly involves in repairing the DNA damage from environment, such as UV light. The function of Rad23 protein involved in DNA damage repair from many environmental f...Protein Rad23, a nucleotide excision repair factor, mainly involves in repairing the DNA damage from environment, such as UV light. The function of Rad23 protein involved in DNA damage repair from many environmental factors has been studied extensively, but it is not clear from ultraviolet irradiation. To further investigate the photo-protective function of Rad23 protein on HeLa cells damaged from UV light irradiation, firstly, HeLa cells were irradiated by UV light and incubated with the fusion protein of pCold-Rad23, then the cell viability and apoptosis rate were detected by MTT and Hoechst33342/Pl fluorescent staining, respectively. The results show that the recombinant Rad23 protein can protect the HeLa cells from UV irradiation, and inhibit the apoptosis of HeLa cell by UV irradiation.展开更多
文摘The plasma membrane(PM)plays an essential role in maintaining cell homeostasis,therefore,timely and effective repair of damage caused by factors such as mechanical rupture,pore-forming toxins,or pore-forming proteins is crucial for cell survival.PM damage induces membrane rupture and stimulates an immune response.However,damage resulting from regulated cell death processes,including pyroptosis,ferroptosis,and necroptosis,cannot be repaired by simple sealing mechanisms and thus,requires specialized repair machinery.Recent research has identified a PM repair mechanism of regulated cell death-related injury,mediated by the endosomal sorting complexes required for transport(ESCRT)machinery.Here,we review recent progress in elucidating the ESCRT machinery-mediated repair mechanism of PM injury,with particular focus on processes related to regulated cell death.This overview,along with continued research in this field,may provide novel insights into therapeutic targets for diseases associated with dysregulation of regulated cell death pathways.
基金Project(K2022G038)supported by the Science Technology Research and Development Program of China State Railway Group Co.,LtdProject(52178405)supported by the National Natural Science Foundation of China。
文摘To address the issue of extreme thermal-induced arching in CRTS II slab tracks due to joint damage,an optimized joint repair model was proposed.First,the formula for calculating the safe temperature rise of the track was derived based on the principle of stationary potential energy.Considering interlayer evolution and structural crack propagation,an optimized joint repair model for the track was established and validated.Subsequently,the impact of joint repair on track damage and arch stability under extreme temperatures was studied,and a comprehensive evaluation of the feasibility of joint repair and the evolution of damage after repair was conducted.The results show that after the joint repair,the temperature rise of the initial damage of the track structure can be increased by 11℃.Under the most unfavorable heating load with a superimposed temperature gradient,the maximum stiffness degradation index SDEG in the track structure is reduced by about 81.16%following joint repair.The joint repair process could effectively reduce the deformation of the slab arching under high temperatures,resulting in a reduction of 93.96%in upward arching deformation.After repair,with the damage to interfacing shear strength,the track arch increases by 2.616 mm.
基金Project(71671035) supported by the National Natural Science Foundation of China
文摘Renewing warranty can provide customers with better service,and thus help manufacturers to gain market opportunities.In engineering practice,the cost for replacement is usually higher than the cost for maintenance,hence manufacturers often face huge challenge to reduce the warranty service cost.With consideration of the warranty deadline,we propose a two-stage optimization model for renewing warranty.In the first stage,a renewing warranty with deadline(RWD)policy is implemented,where the deadline represents the cumulative uptime threshold.When the cumulative uptime exceeds the deadline,the product will be minimally repaired and kept to the residual warranty period.When RWD is expired,the replacement warranty with limited repairs(RWLR)policy is applied.Under the free replacement and pro-rata warranty policy,the corresponding two-stage cost optimization model is established from the manufacturer’s perspective,the aim is to minimize the cost rate and obtain the optimal warranty period.A numerical example is provided to illustrate the validity of the proposed model,and the sensitivity analysis is also carried out.
基金supported by the National Natural Science Foundation of China under Grant No.11201007
文摘This paper deals with a cold standby repairman who can do extra work in idle time. The repairable system with two identical units and one authors are devoted to studying the unique existence and exponential stability of the system solution. C0-semigroup theory is used to prove the existence of a unique nonnegative time-dependent solution of the system. Then by using the theory of resolvent positive operator, the authors derive that dynamic solution of the system exponentially converges to its steady-state one which is the eigenfunction corresponding to eigenvalue 0 of the system operator. Some reliability indices of the system are discussed with a different method from traditional one. The authors also make a profit analysis to determine the optimal service time outside the system to maximize the system profit.
基金supported by the National Natural Science Foundation of China(6110413261304148)
文摘Level of repair analysis（LORA） is an important method of maintenance decision for establishing systems of operation and maintenance in the equipment development period. Currently, the research on equipment of repair level focuses on economic analysis models which are used to optimize costs and rarely considers the maintenance time required by the implementation of the maintenance program. In fact, as to the system requiring high mission complete success, the maintenance time is an important factor which has a great influence on the availability of equipment systems. Considering the relationship between the maintenance time and the spares stocks level, it is obvious that there are contradictions between the maintenance time and the cost. In order to balance these two factors, it is necessary to build an optimization LORA model. To this end, the maintenance time representing performance characteristic is introduced, and on the basis of spares stocks which is traditionally regarded as a decision variable, a decision variable of repair level is added, and a multi-echelon multiindenture（MEMI） optimization LORA model is built which takes the best cost-effectiveness ratio as the criterion, the expected number of backorder（EBO） as the objective function and the cost as the constraint. Besides, the paper designs a convex programming algorithm of multi-variable for the optimization model, provides solutions to the non-convex objective function and methods for improving the efficiency of the algorithm. The method provided in this paper is proved to be credible and effective according to the numerical example and the simulation result.
基金Project(50538020) supported by the National Natural Science Foundation of ChinaProject(20070421050) supported by China Postdoctoral Science Foundation
文摘An innovative approach to increase structural survivability of concrete and maintain structural durability of concrete was developed in case of earthquakes and typhoons. This approach takes advantage of the superelastic effect of shape memory alloy(SMA) and the cohering characteristic of repairing adhesive. These SMA wires and brittle fibers containing adhesives were embedded into concrete beams during concrete casting to form smart reinforced concrete beams. The self-repairing capacity of smart concrete beams was investigated by three-point bending tests. The experimental results show that SMA wires add self-restoration capacity,the concrete beams recover almost completely after incurring an extremely large deflection and the cracks are closed almost completely by the recovery forces of SMA wires. The number or areas of SMA wires has no influence on the tendency of deformation during loading and the tendency of reversion by the superelasticity. The adhesives released from the broken-open fibers fill voids and cracks. The repaired damage enables continued function and prevents further degradation.
基金supported by the National Natural Science Foundation of China (71071020 60705036)Beijing Excellent Doctoral Dissertation Instructor Project of Humanities and Social Sciences(yb20091000701)
文摘Compared with the classical Markov repairable system, the Markov repairable system with stochastic regimes switching introduced in the paper provides a more realistic description of the practical system. The system can be used to model the dynamics of a repairable system whose performance regimes switch according to the external conditions. For example, to satisfy the demand variation that is typical for the power and communication systems and reduce the cost, these systems usually adjust their operating regimes. The transition rate matrices under distinct operating regimes are assumed to be different and the sojourn times in distinct regimes are governed by a finite state Markov chain. By using the theory of Markov process, Ion channel theory, and Laplace transforms, the up time of the system are studied. A numerical example is given to illustrate the obtained results. The effect of sojourn times in distinct regimes on the availability and the up time are also discussed in the numerical example.
基金Project(51575415)supported by the National Natural Science Foundation of ChinaProject(2016CFA077)supported by the Natural Science Foundation of Hubei Province of ChinaProject(2018-YS-026)supported by the Excellent Dissertation Cultivation Funds of Wuhan University of Technology,China。
文摘The evolution of temperature field of the continual motion induction cladding and the depth of heat affected zone are studied in this study.A three-dimensional finite element model for the point type continual induction cladding is established to investigate temperature distributions of fixed and motion induction cladding modes.The novel inductor is designed for cladding of curved surfaces.The modeling reliability is verified by the temperature measurements.The influence of process parameters on the maximum temperature and the generation and transfer of heat are studied.Quantitative calculation is performed to its melting rate to verify the temperature distribution and microstructures.The results show that a good metallurgical bond can be formed between the cladding layer and substrate.The melting rate gradually falls from the top of the cladding layer to the substrate,and the grain size in the substrate gradually rises.The heat affected zone is relatively small compared to integral heating.
基金supported by the China Postdoctoral Science Foundation(2019M653929)the National Natural Science Foundation of Shandong Province(ZR201910310210)the Green Innovation Science and Technology Plan of Colleges and Universities in Shandong Province(2020KJA014).
文摘The availability of a periodic inspection system under mixed maintenance policies is studied in this paper.To accommodate the characteristic of multiple failure modes for complex systems,the system failures can be divided into two failure modes:hard failure and soft failure.When hard failure occurs,the corresponding corrective maintenance will be performed,taking a random time under the perfect maintenance policy;in contrast,if the soft failure is found,the corresponding preventive maintenance will be performed,taking a random time under the imperfect maintenance policy.The dynamic age setback model is adopted for imperfect maintenance,which can accurately reflect the fault characteristics of the degraded system.Then an analytical model for system steady state availability and instantaneous availability are derived.Moreover,the optimal method to maximize the system steady-state availability through adjusting the inspection interval is researched.According to the above research,the optimization of system unit time cost,preventive maintenance intervals and availability is researched.Finally,the developed approach is demonstrated by a numerical example.
基金supported by the National Natural Science Foundation of China(7147114771631001)+1 种基金the Basic Research Project of Natural Science in Shaanxi Province(2015JQ7273)the 111 Project(B13044)
文摘The reliability of the product sold under a warranty is usually maintained by the manufacturer during the warranty period. After the expiry of the warranty, however, the consumer confronts a problem about how to maintain the reliability of the product. This paper proposes, from the consumer's perspective, a replacement policy after the extended warranty, under the assumption that the product is sold under the renewable free replacement warranty (RFRW) policy in which the replacement is dependent on the repair-cost threshold. The proposed replacement policy is the replacement after the extended warranty is performed by the consumer based on the repair-cost threshold or preventive replacement (PR) age, which are decision variables. The expected cost rate model is derived from the consumer's perspective. The existence and uniqueness of the optimal solution that minimizes the expected cost rate per unit time are offered. Finally, a numerical example is presented to exemplify the proposed model.
基金supported by the National Natural Science Foundation of China(51775090)。
文摘Due to the simplicity and flexibility of the power law process,it is widely used to model the failures of repairable systems.Although statistical inference on the parameters of the power law process has been well developed,numerous studies largely depend on complete failure data.A few methods on incomplete data are reported to process such data,but they are limited to their specific cases,especially to that where missing data occur at the early stage of the failures.No framework to handle generic scenarios is available.To overcome this problem,from the point of view of order statistics,the statistical inference of the power law process with incomplete data is established in this paper.The theoretical derivation is carried out and the case studies demonstrate and verify the proposed method.Order statistics offer an alternative to the statistical inference of the power law process with incomplete data as they can reformulate current studies on the left censored failure data and interval censored data in a unified framework.The results show that the proposed method has more flexibility and more applicability.
基金Project(2019-00899-1-1)supported by the Ministry of Industry and Information Technology of ChinaProject(2021JM-060)supported by the Natural Science Foundation of Shaanxi Province,ChinaProject(3102019QD0409)supported by the Fundamental Research Funds for the Central Universities,China。
文摘The application of mixed powders with different mass fraction on laser additive repairing(LAR)can be an effective way to guarantee the performance and functionality of repaired part in time.A convenient and feasible approach is presented to repair TA15 forgings by employing Ti6Al4V-xTA15 mixed powders in this paper.The performance compatibility of Ti6Al4V-xTA15 powders from the aspects of microhardness,tensile property,heat capacity,thermal expansion coefficient and corrosion resistance with the TA15 forgings was fully investigated.The primaryαlaths were refined and the volume fraction of the secondaryαphase was increased by increasing the mass fraction of TA15 in the mixed Ti6Al4V-xTA15 powders,leading to varied performances.In conclusion,the mixed Ti6Al4V-70%TA15(x=70%)powders is the most suitable candidate and is recommended as the raw material for LAR of TA15 forgings based on overall consideration of the compatibility calculations of the laser repaired zone with the wrought substrate zone.
文摘Objective Acute Stanford type A aortic dissection is typically presented as antegrade dissection from a primary intimal tear in the proximal ascending aorta extending to the arch and the downstream distal aorta.However,it may also develop in a retrograde fashion with an intimal tear located in descending aorta causing retrograde extension of aortic dissection into ascending aorta,namely,retrograde type A aortic dissection(RTAAD).Though open surgery remains the golden standard to treat type A dissection,as to RTAAD,the distal location of its primary entry tear in descending aorta warrants more extensive aortic repair with higher surgical risks of mortality or morbidity through a median sternotomy.Conversely,confining the surgical extent to the proximal aorta leaves the risks of complications related to the residual tear in the distal aorta untreated.More recently,thoracic endovascular aortic repair(TEVAR)is attempted for the treatment of RTAAD with favorable shortterm and long-term prognosis.To the best of our knowledge,this was the largest serial study to apply TEVAR in the treatment of RTAAD.
基金supported by the National Natural Science Foundation of China(6110118461174159)
文摘Electromagnetic detection satellite（EDS） is a type of Earth observation satellite（EOS）. Satellites observation and data down-link scheduling plays a significant role in improving the efficiency of satellite observation systems. However, the current works mainly focus on the scheduling of imaging satellites, little work focuses on the scheduling of EDSes for its specific requirements.And current works mainly schedule satellite resources and data down-link resources separately, not considering them in a globally optimal perspective. The EDSes and data down-link resources are scheduled in an integrated process and the scheduling result is searched globally. Considering the specific constraints of EDS, a coordinate scheduling model for EDS observation tasks and data transmission jobs is established and an algorithm based on the genetic algorithm is proposed. Furthermore, the convergence of our algorithm is proved. To deal with some specific constraints, a solution repairing algorithm of polynomial computing time is designed. Finally, some experiments are conducted to validate the correctness and practicability of our scheduling algorithms.
基金supported by grants from the National Natural Science Foundation of China (10872131,81172549,31271015)a grant from the Shanghai Science and Technology Development Fund (11XD1403300)the key disciplines program of the Shanghai Municipal Education Commission(J50206)
文摘Bone marrow derived mesenchymal stem cells(MSCs)have been widely used to promote the repair or regeneration of damaged tissues.In previous studies,we have developed several stem cells based strategies to promote the bone repair,which includes the BMP-2 gene medicine,construction of tissue engineering bone in bioreactor and clinical trial of enriched stem cell therapy.Among these studies,one challenge is to construct the tissue engineered bone at the large scale which face the problem of poor survivor of seeding cells in the scaffold interior.In our studies,the porousβ-TCP cylindrical scaffolds loading with MSCs were continuously perfused by a customized bioreactor(dynamic culture)at different flow rate or were immersed
文摘In the past,most hydrogel composites of bone repair derived from either natural or chemical synthesis were lack of mechanical strength.So we used high strengthened PAA-Ch-Si hydrogel compounds and it containing PRP(platelet-rich-plasma)material.They were prepared by UV light or y-ray irradiation method for scaffold material application in this paper.We exploited nanosized silica solution,natural chitosan and acrylic acid(AAc)as starting material to synthesize chitosan/hydrogel biomedical products.This biocompatible osteoconductive scaffold mixed with platelet glue to perform the biocompatibility tests for a composite bone graft material and be ap-
文摘The essence of gene therapy is to placefunctioning genes into a patient’s cells for therapeuticpurposes. Gene therapy may be employed to ①enhance anti-tumor immune responses; ②
基金The project supported by National High-tech R&D Program of China 863 Program Grant(2009AA022704)National Natural Science Foundation of China(81573463,81173129,81202595 and NIH Grant CA 94961)
文摘OBJECTIVE To investigate the role of e IF3a in the regulation of DNA repair pathways in cancer chemotherapeutic response.METHODS Immunohistochemistry was used to determine the expression of e IF3a in lung and breast cancer tissues followed by association analysis of e IF3a expression with patient′s response to chemotherapy.Ectopic overexpression and RNA interference knockdown of e IF3a were carried out in NIH3T3and H1299 cell lines,respectively,to determine the effect of altered e IF3a expression on cellular response to chemotherapeutic drugs by using MTT assay.The DNA repair capacity of these cells was evaluated by using host-cell reactivation,NHEJ and HR assay.Real-time reverse transcriptase PCR and Western Blot analyses were carried out to determine the effect of e IF3a on the DNA repair genes by using cells with altered e IF3a expression.RESULTS e IF3a expression associates with response of lung and breast cancer patients to platinum and anthracycline.e IF3a knockdown or overexpression,respectively,increased and decreased the cellular resistance to cisplatin and anthracycline anticancer drugs,DNA repair activity,and expression of NER and NHEJ DNA repair proteins.CONCLUSION e IF3a plays an important role in regulating the expression of NER and NHEJ DNA repair proteins which,in turn,contributes to cellular response to DNA-damaging anticancer drugs and patients′response to platinum and anthracycline chemotherapy.
基金Project(31171176)supported by the National Natural Science Foundation of China
文摘Protein Rad23, a nucleotide excision repair factor, mainly involves in repairing the DNA damage from environment, such as UV light. The function of Rad23 protein involved in DNA damage repair from many environmental factors has been studied extensively, but it is not clear from ultraviolet irradiation. To further investigate the photo-protective function of Rad23 protein on HeLa cells damaged from UV light irradiation, firstly, HeLa cells were irradiated by UV light and incubated with the fusion protein of pCold-Rad23, then the cell viability and apoptosis rate were detected by MTT and Hoechst33342/Pl fluorescent staining, respectively. The results show that the recombinant Rad23 protein can protect the HeLa cells from UV irradiation, and inhibit the apoptosis of HeLa cell by UV irradiation.
