Natural photosynthesis,the cornerstone of life on Earth,has long inspired sustainable chemistry by converting solar energy into chemical energy,thereby maintaining atmospheric balance and supporting biological product...Natural photosynthesis,the cornerstone of life on Earth,has long inspired sustainable chemistry by converting solar energy into chemical energy,thereby maintaining atmospheric balance and supporting biological productivity.Mimicking this natural process,photocatalysis has emerged as a promising strategy for harnessing solar energy to drive chemical reactions with minimal environmental impact.This versatile approach finds applications in pollutant degradation,water purification,energy conversion,and organic synthesis.However,a major limitation of single-component photocatalysts is the rapid recombination of photogenerated charge carriers,significantly reducing their efficiency.展开更多
Tooth morphogenesis is orchestrated by a complex interplay of signaling pathways and transcription factors that control cell proliferation,apoptosis,and differentiation,with the Wnt/β-catenin signaling pathway playin...Tooth morphogenesis is orchestrated by a complex interplay of signaling pathways and transcription factors that control cell proliferation,apoptosis,and differentiation,with the Wnt/β-catenin signaling pathway playing a pivotal role.However,the comprehensive regulatory mechanisms of Wnt/β-catenin signaling remain largely unclear.Smad7,a key antagonist of the TGF-βsuperfamily,is essential for maintaining tissue homeostasis and ensuring proper cellular function.Our previous study has demonstrated that Smad7 knockout in mice leads to impaired proliferative property of tooth germ cells,resulting in small molars.Here,we identified SMAD7 expression in human dental papilla and dental pulp,colocalized with β-CATENIN and cell proliferationrelated proteins.RNA sequencing analysis revealed a significant reduction in Wnt signaling activity in Smad7-deficient mouse tooth germs.Using lentivirus transfection,we established SMAD7-knockdown human dental papilla stem cells,which manifested remarkably blunt proliferation rate,along with diminished Wnt signaling activity.In vivo transplantation investigations further revealed the indispensable role of SMAD7 in dentin formation.Mechanistically,we revealed that β-CATENIN interacts with P-SMAD2/3 and SMAD7 through co-immunoprecipitation and yeast two-hybrid assays.Inhibition of TGF-β pathway or disruption of SMAD7/β-CATENIN transcription factor complex formation potently impacted Wnt/β-catenin activities,indicating both direct and indirect regulatory mechanisms.These findings highlight the critical role of SMAD7 in the proliferation and diffe rentiation of human dental stem cells,which could contribute to dental tissue regeneration and engineering.展开更多
Microglia cells are the resident innate immune cells of the central nervous system(CNS)(Paolicelli et al.,2022).They play a pivotal role in CNS development and in maintaining homeostasis during adulthood.Microglia are...Microglia cells are the resident innate immune cells of the central nervous system(CNS)(Paolicelli et al.,2022).They play a pivotal role in CNS development and in maintaining homeostasis during adulthood.Microglia are being extensively studied for their involvement in CNS disorders,ranging from autoimmune diseases such as multiple sclerosis to neurodegenerative and psychiatric conditions,as well as stroke and brain tumors(Paolicelli et al.,2022).展开更多
The rise of the aging population parallels the rapidly increasing cases of neurological disorders. This puts pressure on scientists and physicians to find novel methods that can prevent and treat neurodegeneration. Th...The rise of the aging population parallels the rapidly increasing cases of neurological disorders. This puts pressure on scientists and physicians to find novel methods that can prevent and treat neurodegeneration. The brain is made up of a complex network of different cell types that work in tandem to maintain systemic homeostasis.展开更多
Dendritic spines are small protrusions along dendrites that contain most of the excitatory synapses in principal neurons,playing a crucial role in neuronal function by creating a compartmentalized environment for sign...Dendritic spines are small protrusions along dendrites that contain most of the excitatory synapses in principal neurons,playing a crucial role in neuronal function by creating a compartmentalized environment for signal transduction.The plasticity of spine morphologies provides a tunable handle to regulate calcium signal dynamics,allowing rapid regulation of protein expression necessary to establish and maintain synapses(Cornejo et al.,2022).If excitatory inputs were to be located primarily on dendritic shafts,dendrites would frequently short-circuit,preventing voltage signals from propagating(Cornejo et al.,2022).It is thus not surprising that the structural plasticity of dendritic spines is closely linked to synaptic plasticity and memory formation(Berry and Nedivi,2017).While comprehensive in vitro studies have been conducted,in vivo studies that directly tackle the mechanism of dendritic transport and translation in regulating spine plasticity spatiotemporally are limited.展开更多
To improve the mainlainability design efficiency and quality, a layout optimization method for maintainability of multi-component systems was proposed. The impact of the component layout design on system maintainabili...To improve the mainlainability design efficiency and quality, a layout optimization method for maintainability of multi-component systems was proposed. The impact of the component layout design on system maintainability was analyzed, and the layout problem for maintainability was presented. It was formulated as an optimization problem, where maintainability, layout space and distance requirement were formulated as objective functions. A multi-objective particle swarm optimization algorithm, in which the constrained-domination relationship and the update strategy of the global best were simply modified, was then used to obtain Pareto optimal solutions for the maintainability layout design problem. Finally, application in oxygen generation system of a spacecraft was studied in detail to illustrate the effectiveness and usefulness of the proposed method. The results show that the concurrent maintainability design can be carried out during the layout design process by solving the layout optimization problem for maintainability.展开更多
With the development of high-speed railways in China,more than 2000 high-speed trains will be put into use.Safety and efficiency of railway transportation is increasingly important.We have designed a high availability...With the development of high-speed railways in China,more than 2000 high-speed trains will be put into use.Safety and efficiency of railway transportation is increasingly important.We have designed a high availability quadruple vital computer (HAQVC) system based on the analysis of the architecture of the traditional double 2-out-of-2 system and 2-out-of-3 system.The HAQVC system is a system with high availability and safety,with prominent characteristics such as fire-new internal architecture,high efficiency,reliable data interaction mechanism,and operation state change mechanism.The hardware of the vital CPU is based on ARM7 with the real-time embedded safe operation system (ES-OS).The Markov modeling method is designed to evaluate the reliability,availability,maintainability,and safety (RAMS) of the system.In this paper,we demonstrate that the HAQVC system is more reliable than the all voting triple modular redundancy (AVTMR) system and double 2-out-of-2 system.Thus,the design can be used for a specific application system,such as an airplane or high-speed railway system.展开更多
Mine refuge chambers are used to shield miners who fail to escape from the mine when incidents occur. Environment maintaining system plays a key role in stabilizing thermal environment of a mine refuge chamber against...Mine refuge chambers are used to shield miners who fail to escape from the mine when incidents occur. Environment maintaining system plays a key role in stabilizing thermal environment of a mine refuge chamber against heat emitted from metabolism and transferred from outside. The safety and comfort of refugees are closely related to the environment maintaining system design. In order to improve the comfort of refugees, optimization on the environment maintaining system has been done based on the previous work. To evaluate the environment of the chamber, eight volunteers were involved into the experiment. Under close observation and safety protection, they lived in a heat-isolated test chamber for 106 hours. The volunteers were asked to maintain low level of activities to simulate refugees＇ situation. It shows that the environment maintaining system worked well and the temperature, relative humidity and emitted harmful air content such as CO2 and CO were all kept in the safety level, and no discomfort was felt by volunteers at all.展开更多
Introduction:3D bio-printing technology<sup>[1-3]</sup>（Figure 1）capable of dispensing live cells,soluble factors,and phase-changing hydrogel in a desired pattern,has great potential in creating 3D tissu...Introduction:3D bio-printing technology<sup>[1-3]</sup>（Figure 1）capable of dispensing live cells,soluble factors,and phase-changing hydrogel in a desired pattern,has great potential in creating 3D tissue.However,maintaining the viability of a thick tissue structure during tissue growth and maturation is challenging due to lack of adequate vascular perfusion.In a simple tissue model with展开更多
This study describes an automatic berthing system with mooring lines. It is designed to be berthed by using mooring device on the upper deck of a ship. It is to berth once maintaining parallel with the quay by control...This study describes an automatic berthing system with mooring lines. It is designed to be berthed by using mooring device on the upper deck of a ship. It is to berth once maintaining parallel with the quay by controlling both forward and aft breast lines. Berthing method is used through length adjustment of mooring lines connected between ship and quay by controlling the angular velocity and the torque of hydraulic motor in mooring device. The study is conducted under three changing conditions of draft, such as even-keel, rise of the gravity center and trim to stern. Variables affecting berthing stability are determined based on the control performance of each condition. Bond graphs method is used to model the system. Controller is designed as PID control method of reference-model algorithm. The control program is composed of synchronous control system based on the equations derived with the numerical analysis. The tank test is conducted to verify the usefulness of the control program.展开更多
Aiming at the shortcomings of the traditional maintenance plan of a launching system, an analysis was made on the development of the reliability centered maintenance methods （RCM） and the basic models for reliabilit...Aiming at the shortcomings of the traditional maintenance plan of a launching system, an analysis was made on the development of the reliability centered maintenance methods （RCM） and the basic models for reliability centered maintenance of a launching system are presented in this paper. The common methods for functional impor- tant product determination, failure modes and effect analysis （ FMEA ） and logic decision analysis were illustrated and the basic methods for maintenance interval calculation models were studied based on availability. According to the research, the reliability centered maintenance plan of a certain launching system was given.展开更多
Maintainability is an important design characterist ic , and also is a design parameter. The essence of maintainability design is to ex pect and solve possible maintenance problems at early stage during product devel ...Maintainability is an important design characterist ic , and also is a design parameter. The essence of maintainability design is to ex pect and solve possible maintenance problems at early stage during product devel opment, maintainability must be designed into product simultaneously. But curren t maintainability methods do not support concurrent engineering. This paper anal yzes the deficiencies of existing maintainability technologies, and introduces t he concept of maintainability analysis visualization. The two major deficiencies are that maintainability analysis time lags behind product design, and the main tainability techniques do not accommodate modern product design concepts. After this, the infrastructure of maintainability analysis visualization system is dis cussed. The system are composed of four subsystems, they are product modeling, d isassembly process modeling, simulation and analysis, and user interface. Produc t modeling is accomplished with the capability of CAD system, disassembly proces s modeling is mainly a reason process based on assembly information. The system is integrated into AutoCAD so that designer can timely analyze their product des ign from the viewpoint of easy maintenance. Human model generation function, hum an task analysis function, tool analysis function, visibility analysis function is implemented, disassembly process planning function is still under developing.展开更多
Silicosis,a potentially fatal global occupational disease, is characterized by progressive deterioration of pulmonary function and irreversible fibrosis resulting from crystalline silicon dioxide or silica inhalation....Silicosis,a potentially fatal global occupational disease, is characterized by progressive deterioration of pulmonary function and irreversible fibrosis resulting from crystalline silicon dioxide or silica inhalation.Extensive pieces of evidence[1-3]manifest that inhaled silica particles could directly or indirectly cause excess generation of reactive oxygen species(ROS),which plays a key role in the pathogenesis of silicosis.In order to maintain the cellular redox balance,the main function of thioredoxin(Trx)/thioredoxin reductase(TrxR)systems is to scavenge the ROS. TrxR, as a reductase of Trx currently known only,has the function of antioxidation and scavenging free radicals[4].In addition, recent in vitro studies demonstrate that Trx interacts directly with and inhibits the activity of apoptosis-regulating kinase-1(ASK-1)[5].The damaged cell of lung tissue caused by ROS may be an important link to ASK-1 triggered cell apoptosis.Zhu et al.[1] reported that silica could aggravate oxidative stress and promote the development of silicosis in rat lungs after silica exposure by downregulating the expression of TrxR and poor Trx activity. The specific mechanism of imbalance of reduction/oxidation status in silicosis is poorly understood.Our previous studies[6]demonstrated that oxidative stress in rats induced by silica leads to increased peroxiredoxins(Prxs) protein reactivity to resist oxidative stress, and Trx as an electron donor is functionally associated with Prxs. Hence, we propose a hypothesis that silica exposure may lead to the disturbance of the function of the Trx/TrxR system,contributing to further oxidative damage.展开更多
During maintainability demonstration,the maintenance time for complex systems consisting of mixed technologies generally conforms to a mixture distribution.However existing maintainability standards and guidance do no...During maintainability demonstration,the maintenance time for complex systems consisting of mixed technologies generally conforms to a mixture distribution.However existing maintainability standards and guidance do not explain explicitly how to deal with this situation.This paper develops a comprehensive maintainability demonstration method for complex systems with a mixed maintenance time distribution.First of all,a K-means algorithm and an expectation-maximization(EM)algorithm are used to partition the maintenance time data for all possible clusters.The Bayesian information criterion(BIC)is then used to choose the optimal model.After this,the clustering results for equipment are obtained according to their degree of membership.The degree of similarity for the maintainability of different kinds of equipment is then determined using the projection method.By using a Bootstrap method,the prior distribution is obtained from the maintenance time data for the most similar equipment.Then,a test method based on Bayesian theory is outlined for the maintainability demonstration.Finally,the viability of the proposed approach is illustrated by means of an example.展开更多
Price mechanism is one of the important major parts of economy activity. One of the elementary function of price is to disipose the social resources adequately, After 1953, the state began to reform our vigid price sy...Price mechanism is one of the important major parts of economy activity. One of the elementary function of price is to disipose the social resources adequately, After 1953, the state began to reform our vigid price system. The basic means is: to shrink展开更多
The variable-speed constant-frequency wind electric conver-sion system can allow the rotational speed of wind turbine to varywith wind speed and operate at a constant and optimal tip speedratio. Therefore, the wind tu...The variable-speed constant-frequency wind electric conver-sion system can allow the rotational speed of wind turbine to varywith wind speed and operate at a constant and optimal tip speedratio. Therefore, the wind turbine can maintain high power coeffi-cient over wide range of wind speed and the speed regulatingmechanism of wind trubine can be simplified.展开更多
Summary1.There are 12 power systems including 5 regional powersystems with over 1000MW of capacity each.In 1989 Central andEast China power systems were interconnected by a±500kV HVDC Line.2.The hierarchical cont...Summary1.There are 12 power systems including 5 regional powersystems with over 1000MW of capacity each.In 1989 Central andEast China power systems were interconnected by a±500kV HVDC Line.2.The hierarchical control organization can be divided into 5levels,i.e.NCC,6 RCCs,25 PCCs,250 DCCs and more than 2000CCCs. 3.All control centers will be equipped with SCADA and EMSin the near future.4.China power system has a large,dedicated communicationnetwork of its own.展开更多
"In 2023,China's photovoltaic industry continued to maintain a rapid development momentum,with an additional installed capacity of more than 216 GW,accounting for more than half of the global total.The cumula..."In 2023,China's photovoltaic industry continued to maintain a rapid development momentum,with an additional installed capacity of more than 216 GW,accounting for more than half of the global total.The cumulative installed capacity is close to 610 GW,which helps the installed capacity of renewable energy surpass that of thermal power historically.In 2023,the output value of the domestic photovoltaic manufacturing industry exceeded RMB1.75 trillion,a year-on-year increase of 17.1%,and the output of the four main industrial chains of polysilicon.展开更多
May 23-24,Faroe Islands The 7th International Hybrid Power Plants&Systems Workshop offers a prime opportunity to discuss the future of hybrid power systems.One challenge of island grids and micro-grids is to maint...May 23-24,Faroe Islands The 7th International Hybrid Power Plants&Systems Workshop offers a prime opportunity to discuss the future of hybrid power systems.One challenge of island grids and micro-grids is to maintain the balance between production and consumption.Diesel generators are still frequently used for this task.Due to the unavoidable dependence on fuel price and delivery options,and the environmental impact,alternatives are being sought.Wind and solar power are independent of imported fuels and environmentally friendly,and therefore the logical choice for island and micro-grids.展开更多
Strengthening alliances and building coalitions has always been the core strategy for the United States to maintain its global hegemony.1 Currently,the United States is concentrating its efforts on strengthening the c...Strengthening alliances and building coalitions has always been the core strategy for the United States to maintain its global hegemony.1 Currently,the United States is concentrating its efforts on strengthening the coalition system in the Indo-Pacific to balance China’s growing influence in the region.展开更多
文摘Natural photosynthesis,the cornerstone of life on Earth,has long inspired sustainable chemistry by converting solar energy into chemical energy,thereby maintaining atmospheric balance and supporting biological productivity.Mimicking this natural process,photocatalysis has emerged as a promising strategy for harnessing solar energy to drive chemical reactions with minimal environmental impact.This versatile approach finds applications in pollutant degradation,water purification,energy conversion,and organic synthesis.However,a major limitation of single-component photocatalysts is the rapid recombination of photogenerated charge carriers,significantly reducing their efficiency.
基金supported by the National Key Research and Development Program of China to W.Tian (2022YFA1104400)the National Natural Science Foundation of China to T.Chen (82100959)a grant from the Sichuan Science and Technology Program to Z.Liu (2024YFFK0068)。
文摘Tooth morphogenesis is orchestrated by a complex interplay of signaling pathways and transcription factors that control cell proliferation,apoptosis,and differentiation,with the Wnt/β-catenin signaling pathway playing a pivotal role.However,the comprehensive regulatory mechanisms of Wnt/β-catenin signaling remain largely unclear.Smad7,a key antagonist of the TGF-βsuperfamily,is essential for maintaining tissue homeostasis and ensuring proper cellular function.Our previous study has demonstrated that Smad7 knockout in mice leads to impaired proliferative property of tooth germ cells,resulting in small molars.Here,we identified SMAD7 expression in human dental papilla and dental pulp,colocalized with β-CATENIN and cell proliferationrelated proteins.RNA sequencing analysis revealed a significant reduction in Wnt signaling activity in Smad7-deficient mouse tooth germs.Using lentivirus transfection,we established SMAD7-knockdown human dental papilla stem cells,which manifested remarkably blunt proliferation rate,along with diminished Wnt signaling activity.In vivo transplantation investigations further revealed the indispensable role of SMAD7 in dentin formation.Mechanistically,we revealed that β-CATENIN interacts with P-SMAD2/3 and SMAD7 through co-immunoprecipitation and yeast two-hybrid assays.Inhibition of TGF-β pathway or disruption of SMAD7/β-CATENIN transcription factor complex formation potently impacted Wnt/β-catenin activities,indicating both direct and indirect regulatory mechanisms.These findings highlight the critical role of SMAD7 in the proliferation and diffe rentiation of human dental stem cells,which could contribute to dental tissue regeneration and engineering.
文摘Microglia cells are the resident innate immune cells of the central nervous system(CNS)(Paolicelli et al.,2022).They play a pivotal role in CNS development and in maintaining homeostasis during adulthood.Microglia are being extensively studied for their involvement in CNS disorders,ranging from autoimmune diseases such as multiple sclerosis to neurodegenerative and psychiatric conditions,as well as stroke and brain tumors(Paolicelli et al.,2022).
文摘The rise of the aging population parallels the rapidly increasing cases of neurological disorders. This puts pressure on scientists and physicians to find novel methods that can prevent and treat neurodegeneration. The brain is made up of a complex network of different cell types that work in tandem to maintain systemic homeostasis.
基金supported by the National Natural Science Foundation of China(NSFC/RGC/JRF N_HKU735/21)Research Grant Council of Hong Kong,China(17102120,17108821,17103922,C1024-22GF,C7074-21G)+1 种基金Health and Medical Research Fund(HMRF 09200966)(to CSWL)FRQS Postdoctoral Fellowship(to AHKF).
文摘Dendritic spines are small protrusions along dendrites that contain most of the excitatory synapses in principal neurons,playing a crucial role in neuronal function by creating a compartmentalized environment for signal transduction.The plasticity of spine morphologies provides a tunable handle to regulate calcium signal dynamics,allowing rapid regulation of protein expression necessary to establish and maintain synapses(Cornejo et al.,2022).If excitatory inputs were to be located primarily on dendritic shafts,dendrites would frequently short-circuit,preventing voltage signals from propagating(Cornejo et al.,2022).It is thus not surprising that the structural plasticity of dendritic spines is closely linked to synaptic plasticity and memory formation(Berry and Nedivi,2017).While comprehensive in vitro studies have been conducted,in vivo studies that directly tackle the mechanism of dendritic transport and translation in regulating spine plasticity spatiotemporally are limited.
基金Project(51005238)supported by the National Natural Science Foundation of China
文摘To improve the mainlainability design efficiency and quality, a layout optimization method for maintainability of multi-component systems was proposed. The impact of the component layout design on system maintainability was analyzed, and the layout problem for maintainability was presented. It was formulated as an optimization problem, where maintainability, layout space and distance requirement were formulated as objective functions. A multi-objective particle swarm optimization algorithm, in which the constrained-domination relationship and the update strategy of the global best were simply modified, was then used to obtain Pareto optimal solutions for the maintainability layout design problem. Finally, application in oxygen generation system of a spacecraft was studied in detail to illustrate the effectiveness and usefulness of the proposed method. The results show that the concurrent maintainability design can be carried out during the layout design process by solving the layout optimization problem for maintainability.
基金Project(No.2009BAG12A05) supported by the National Key Technology R&D Program of China
文摘With the development of high-speed railways in China,more than 2000 high-speed trains will be put into use.Safety and efficiency of railway transportation is increasingly important.We have designed a high availability quadruple vital computer (HAQVC) system based on the analysis of the architecture of the traditional double 2-out-of-2 system and 2-out-of-3 system.The HAQVC system is a system with high availability and safety,with prominent characteristics such as fire-new internal architecture,high efficiency,reliable data interaction mechanism,and operation state change mechanism.The hardware of the vital CPU is based on ARM7 with the real-time embedded safe operation system (ES-OS).The Markov modeling method is designed to evaluate the reliability,availability,maintainability,and safety (RAMS) of the system.In this paper,we demonstrate that the HAQVC system is more reliable than the all voting triple modular redundancy (AVTMR) system and double 2-out-of-2 system.Thus,the design can be used for a specific application system,such as an airplane or high-speed railway system.
文摘Mine refuge chambers are used to shield miners who fail to escape from the mine when incidents occur. Environment maintaining system plays a key role in stabilizing thermal environment of a mine refuge chamber against heat emitted from metabolism and transferred from outside. The safety and comfort of refugees are closely related to the environment maintaining system design. In order to improve the comfort of refugees, optimization on the environment maintaining system has been done based on the previous work. To evaluate the environment of the chamber, eight volunteers were involved into the experiment. Under close observation and safety protection, they lived in a heat-isolated test chamber for 106 hours. The volunteers were asked to maintain low level of activities to simulate refugees＇ situation. It shows that the environment maintaining system worked well and the temperature, relative humidity and emitted harmful air content such as CO2 and CO were all kept in the safety level, and no discomfort was felt by volunteers at all.
基金funded by the American Heart Association Scientist Development Grant SDG12050083National Institutes of Health grant R21 HL102773
文摘Introduction:3D bio-printing technology<sup>[1-3]</sup>（Figure 1）capable of dispensing live cells,soluble factors,and phase-changing hydrogel in a desired pattern,has great potential in creating 3D tissue.However,maintaining the viability of a thick tissue structure during tissue growth and maturation is challenging due to lack of adequate vascular perfusion.In a simple tissue model with
基金financially supported by the Post Innovation Program of the Fisheries Science Institute of Chonnam National University
文摘This study describes an automatic berthing system with mooring lines. It is designed to be berthed by using mooring device on the upper deck of a ship. It is to berth once maintaining parallel with the quay by controlling both forward and aft breast lines. Berthing method is used through length adjustment of mooring lines connected between ship and quay by controlling the angular velocity and the torque of hydraulic motor in mooring device. The study is conducted under three changing conditions of draft, such as even-keel, rise of the gravity center and trim to stern. Variables affecting berthing stability are determined based on the control performance of each condition. Bond graphs method is used to model the system. Controller is designed as PID control method of reference-model algorithm. The control program is composed of synchronous control system based on the equations derived with the numerical analysis. The tank test is conducted to verify the usefulness of the control program.
文摘Aiming at the shortcomings of the traditional maintenance plan of a launching system, an analysis was made on the development of the reliability centered maintenance methods （RCM） and the basic models for reliability centered maintenance of a launching system are presented in this paper. The common methods for functional impor- tant product determination, failure modes and effect analysis （ FMEA ） and logic decision analysis were illustrated and the basic methods for maintenance interval calculation models were studied based on availability. According to the research, the reliability centered maintenance plan of a certain launching system was given.
文摘Maintainability is an important design characterist ic , and also is a design parameter. The essence of maintainability design is to ex pect and solve possible maintenance problems at early stage during product devel opment, maintainability must be designed into product simultaneously. But curren t maintainability methods do not support concurrent engineering. This paper anal yzes the deficiencies of existing maintainability technologies, and introduces t he concept of maintainability analysis visualization. The two major deficiencies are that maintainability analysis time lags behind product design, and the main tainability techniques do not accommodate modern product design concepts. After this, the infrastructure of maintainability analysis visualization system is dis cussed. The system are composed of four subsystems, they are product modeling, d isassembly process modeling, simulation and analysis, and user interface. Produc t modeling is accomplished with the capability of CAD system, disassembly proces s modeling is mainly a reason process based on assembly information. The system is integrated into AutoCAD so that designer can timely analyze their product des ign from the viewpoint of easy maintenance. Human model generation function, hum an task analysis function, tool analysis function, visibility analysis function is implemented, disassembly process planning function is still under developing.
基金funded by the Basic Scientific Research Funds for Provincial Universities of North China University of Science and Technology [JQN2020013]grants from the National Natural Science Foundation of China [U21A20334]
文摘Silicosis,a potentially fatal global occupational disease, is characterized by progressive deterioration of pulmonary function and irreversible fibrosis resulting from crystalline silicon dioxide or silica inhalation.Extensive pieces of evidence[1-3]manifest that inhaled silica particles could directly or indirectly cause excess generation of reactive oxygen species(ROS),which plays a key role in the pathogenesis of silicosis.In order to maintain the cellular redox balance,the main function of thioredoxin(Trx)/thioredoxin reductase(TrxR)systems is to scavenge the ROS. TrxR, as a reductase of Trx currently known only,has the function of antioxidation and scavenging free radicals[4].In addition, recent in vitro studies demonstrate that Trx interacts directly with and inhibits the activity of apoptosis-regulating kinase-1(ASK-1)[5].The damaged cell of lung tissue caused by ROS may be an important link to ASK-1 triggered cell apoptosis.Zhu et al.[1] reported that silica could aggravate oxidative stress and promote the development of silicosis in rat lungs after silica exposure by downregulating the expression of TrxR and poor Trx activity. The specific mechanism of imbalance of reduction/oxidation status in silicosis is poorly understood.Our previous studies[6]demonstrated that oxidative stress in rats induced by silica leads to increased peroxiredoxins(Prxs) protein reactivity to resist oxidative stress, and Trx as an electron donor is functionally associated with Prxs. Hence, we propose a hypothesis that silica exposure may lead to the disturbance of the function of the Trx/TrxR system,contributing to further oxidative damage.
基金supported by the National Defense Pre-research Funds(9140A27010215JB34422)
文摘During maintainability demonstration,the maintenance time for complex systems consisting of mixed technologies generally conforms to a mixture distribution.However existing maintainability standards and guidance do not explain explicitly how to deal with this situation.This paper develops a comprehensive maintainability demonstration method for complex systems with a mixed maintenance time distribution.First of all,a K-means algorithm and an expectation-maximization(EM)algorithm are used to partition the maintenance time data for all possible clusters.The Bayesian information criterion(BIC)is then used to choose the optimal model.After this,the clustering results for equipment are obtained according to their degree of membership.The degree of similarity for the maintainability of different kinds of equipment is then determined using the projection method.By using a Bootstrap method,the prior distribution is obtained from the maintenance time data for the most similar equipment.Then,a test method based on Bayesian theory is outlined for the maintainability demonstration.Finally,the viability of the proposed approach is illustrated by means of an example.
文摘Price mechanism is one of the important major parts of economy activity. One of the elementary function of price is to disipose the social resources adequately, After 1953, the state began to reform our vigid price system. The basic means is: to shrink
文摘The variable-speed constant-frequency wind electric conver-sion system can allow the rotational speed of wind turbine to varywith wind speed and operate at a constant and optimal tip speedratio. Therefore, the wind turbine can maintain high power coeffi-cient over wide range of wind speed and the speed regulatingmechanism of wind trubine can be simplified.
文摘Summary1.There are 12 power systems including 5 regional powersystems with over 1000MW of capacity each.In 1989 Central andEast China power systems were interconnected by a±500kV HVDC Line.2.The hierarchical control organization can be divided into 5levels,i.e.NCC,6 RCCs,25 PCCs,250 DCCs and more than 2000CCCs. 3.All control centers will be equipped with SCADA and EMSin the near future.4.China power system has a large,dedicated communicationnetwork of its own.
文摘"In 2023,China's photovoltaic industry continued to maintain a rapid development momentum,with an additional installed capacity of more than 216 GW,accounting for more than half of the global total.The cumulative installed capacity is close to 610 GW,which helps the installed capacity of renewable energy surpass that of thermal power historically.In 2023,the output value of the domestic photovoltaic manufacturing industry exceeded RMB1.75 trillion,a year-on-year increase of 17.1%,and the output of the four main industrial chains of polysilicon.
文摘May 23-24,Faroe Islands The 7th International Hybrid Power Plants&Systems Workshop offers a prime opportunity to discuss the future of hybrid power systems.One challenge of island grids and micro-grids is to maintain the balance between production and consumption.Diesel generators are still frequently used for this task.Due to the unavoidable dependence on fuel price and delivery options,and the environmental impact,alternatives are being sought.Wind and solar power are independent of imported fuels and environmentally friendly,and therefore the logical choice for island and micro-grids.
文摘Strengthening alliances and building coalitions has always been the core strategy for the United States to maintain its global hegemony.1 Currently,the United States is concentrating its efforts on strengthening the coalition system in the Indo-Pacific to balance China’s growing influence in the region.
