Aircrafts damages caused by lightning strikes have been known since the early days of aviation.However,the physical effects on the aircraft structure are still being investigated.This work seeks to evaluate the lightn...Aircrafts damages caused by lightning strikes have been known since the early days of aviation.However,the physical effects on the aircraft structure are still being investigated.This work seeks to evaluate the lightning strike effects in the aluminum alloy 7075-T6.Samples were submitted to lightning strike simulation in laboratory and the damages evaluated through characterization techniques.Ultrasound and profilometry tests have shown material loss to 0.272 mm depth in the damaged region.In addition,it was detected the material accumulation occurrence in the damage vicinity of the region.Below the damage,it was found a region where metallurgical changes were identified.The tensile and microhardness tests results have shown reduction in the percentage elongation and hardness increasing in the material affected by lightning.These results are corroborated by the X-Ray Diffraction(XRD)and Rietveld Method(red line)that indicated an increasing in dislocation density and micro-deformation in the material matrix.Optical microscopy results have shown the presence of microcracks on the normal and cross-section surface of the samples damaged.The Energy Dispersive X-Ray Spectroscopy(EDXS)and Electron Backscattered Diffraction Test(EBSD)found coarse intermetallic phases and precipitates compounds with dimensions greater than 1 lm in length.They were responsible for nucleation of the microcracks that propagate along the material grain boundaries.展开更多
This article presents a mathematical model for simulating the mechanical behaviour of lightning strikes and analysing the resulting damage to the soil.This article focuses on the electro-thermal effect and seepage cau...This article presents a mathematical model for simulating the mechanical behaviour of lightning strikes and analysing the resulting damage to the soil.This article focuses on the electro-thermal effect and seepage caused by lightning strikes in particular.Then,a numerical model based on the conservation laws of momentum,mass and energy is developed for soil subjected to lightning strikes.Comparisons to field observations and theoretical calculations are used to demonstrate the efficacy and accuracy of numerical simulations.The findings demonstrate that lightning strikes can cause soils to experience both seepage force and heat stress.Under the calculative condition of this article:by increasing the intrinsic permeability of the soil,k_(p)(≥10^(-10)m^(2)),the seepage force can be effectively reduced,hence reducing the risk of lightning strikes;improving the electrical conductivity of the soil β(≥10^(-1) S/m^(2))and lowering its thermal expansion coefficient(≤10^(-6)K^(-1))can greatly reduce the damage caused by lightning strikes to the soil.The preceding investigations demonstrate that the suggested model is capable of evaluating mechanical damage caused by lightning in the soil,and the findings contribute to a better understanding of soil mechanical response to lightning strikes.展开更多
In this paper, a method to design bird-strike-resistant aircraft structures is presented and illustrated through examples. The focus is on bird strike experiments and simulations. The explicit finite element software ...In this paper, a method to design bird-strike-resistant aircraft structures is presented and illustrated through examples. The focus is on bird strike experiments and simulations. The explicit finite element software PAM-CRASH is employed to conduct bird strike simulations, and a coupled Smooth Particles Hydrodynamic（SPH） and Finite Element（FE） method is used to simulate the interaction between a bird and a target structure. The SPH method is explained, and an SPH bird model is established. Constitutive models for various structural materials, such as aluminum alloys, composite materials, honeycomb, and foam materials that are used in aircraft structures,are presented, and model parameters are identified by conducting various material tests. Good agreements between simulation results and experimental data suggest that the numerical model is capable of predicting the dynamic responses of various aircraft structures under a bird strike,and numerical simulation can be used as a tool to design bird-strike-resistant aircraft structures.展开更多
Since ancient times,lightning disasters have undoubtedly been an unstoppable threat to humanity.During thunderstorms,lightning often damages objects on the ground,such as buildings and structures.Since Franklin invent...Since ancient times,lightning disasters have undoubtedly been an unstoppable threat to humanity.During thunderstorms,lightning often damages objects on the ground,such as buildings and structures.Since Franklin invented the lightning rod in 1752,lightning rods have been used worldwide to prevent direct lightning strikes in various fields such as high-voltage power transmission lines,outdoor chemical sites,highways,land and sea wind farms,and forest lightning fire protection.It has been proven that lightning accidents still occur frequently in places where lightning rods are installed and the protective angle method is used.In order to further study the protective effect of lightning rods and identify the shortcomings of lightning rod protection,negative lightning strikes are taken as the research object,to analyze the limitations of lightning rods in preventing direct lightning strikes from the working principle of lightning rods.展开更多
Traditional lightning protection measures can not solve the problem of superimposed lightning strikes.This paper presents a compressing arc extinguishing lightning protection device,which can solve the problem of supe...Traditional lightning protection measures can not solve the problem of superimposed lightning strikes.This paper presents a compressing arc extinguishing lightning protection device,which can solve the problem of superimposed lightning strikes.This device can extinguish the power frequency continuous current arc quickly in 1-2 ms.It is far less than the response time of relay protection,which can avoid lightning trips and improve the reliability of power supply.The computer simulation and engineering practice show that the compressing arc extinguishing device has good protection effect on superimposed lightning strikes.展开更多
Presented the concept of the natural support strength.The natural support strength,the strike sill,the multifunction retractors (developed by the author) and etc.were used with the technical measures to change the pas...Presented the concept of the natural support strength.The natural support strength,the strike sill,the multifunction retractors (developed by the author) and etc.were used with the technical measures to change the passive support to the initiative support, and the soft rock entry was supported.And its process is simple and less equipment is needed,and the cost is low and the advance rate is high,which can meet the require- ments of actual mining.It solves many support difficult problems.展开更多
Suffering from rampant piracy, China's film, music and software industries look to special measures to counter attack Watching out for pirates has taken on an entirely new meaning for Fang Yunyun. No, she's no...Suffering from rampant piracy, China's film, music and software industries look to special measures to counter attack Watching out for pirates has taken on an entirely new meaning for Fang Yunyun. No, she's not looking through a telescope for a ship loaded with mean-looking sailors brandishing swords. Fang is an executive at an audio-video company in Beijing, and her anti-piracy watch means being on the展开更多
IN 1987, the Fourth International Music Festival was held in Belgrade. When the Chinese song "The Green Leaves’s Love for the Root" was reverberating through the hall, the whole audience held their breath, ...IN 1987, the Fourth International Music Festival was held in Belgrade. When the Chinese song "The Green Leaves’s Love for the Root" was reverberating through the hall, the whole audience held their breath, listening attentively. This song not only moved all the people present but its approach of mode and the smooth and lyric melody left a deep impression on the adjudicators. As a result, this song won the third prize, the highest award any Chinese pop song had ever won at any international contest before 1987. The composer of this song is Gu Jianfen. Since the early 1980s, Gu Jianfen’s compositions have won her various awards in Chinese song contests. In 1985, five of her compositions won "Prize for Songs Favored展开更多
Until recently,the study of language and meaning of cartoons,the media discourses they generate,and their analysis as a creative means of exploring meaning-making processes as semiotic resources have not received much...Until recently,the study of language and meaning of cartoons,the media discourses they generate,and their analysis as a creative means of exploring meaning-making processes as semiotic resources have not received much scholarly attention in Nigeria.Although cartoons that involve the use of satire and humour as visual representations of reality have gained prominence across many media platforms in Nigeria,only a few scholars have examined this from a social semiotics perspective.This has created a gap in the literature,thus creating room for a para-digm shift in the field of social semiotics.This study explores the semiotics of car-toons in selected Nigerian newspapers to examine the meaning-making resources employed in the visual representation of ASUU strikes in Nigeria.The study,there-fore,examines how cartoonists manipulate symbols,signs,and other semiotic resources to convey specific meanings through visual and textual representations.The study adopts a qualitative research design;data comprising cartoons sourced from selected Vanguard Newspapers and websites are analyzed using Kress and Van Leeuwen's visual semiotics and interpreted from the standpoints of Halliday's Systematic Functional Linguistics(SFL)approach and O'Halloran's position on metaphorical constructions of meaning.Here,metaphorical manipulation and rep-resentation of visual elements in the selected cartoons are interrogated.Findings from the study show the use of semiotic resources in the portrayer of reality in the context of the seemingly intractable ASUU strikes and their consequences on aca-demic activities in Nigeria.This scholarly intervention deserves attention as it significantly contributes to the field of social semiotics through its visual represen-tation in portraying challenges faced by the educational systems in Nigeria vis-a-vis poorgovernment funding.展开更多
0n October 14,the China National Computer Virus Emergency Response Center,the National Engineering Laboratory for Computer Virus Prevention Technology and 360 Digital Security Group jointly released a report,Volt Typh...0n October 14,the China National Computer Virus Emergency Response Center,the National Engineering Laboratory for Computer Virus Prevention Technology and 360 Digital Security Group jointly released a report,Volt Typhoon III:A Cyber Espionage and Disinformation Campaign Conducted by U.S.Government Agencies,to unveil the U.S.-staged so-called"Volt Typhoon"farce.This is the third strike China conducted in 2024 on the Washingtonstyle play script of Catch Me if You Can.展开更多
In 1891,a New York surgeon named William Coley injected cancer patients with live bacteria,observing with fascination as some tumors shrank amid raging fevers.His crude experiments-later deemed reckless-nonetheless re...In 1891,a New York surgeon named William Coley injected cancer patients with live bacteria,observing with fascination as some tumors shrank amid raging fevers.His crude experiments-later deemed reckless-nonetheless revealed a tantalizing truth:The immune system,when properly provoked,could attack cancer.Over a century later,researchers have transformed this observation into a precision strike force.展开更多
Drone swarm systems,equipped with photoelectric imaging and intelligent target perception,are essential for reconnaissance and strike missions in complex and high-risk environments.They excel in information sharing,an...Drone swarm systems,equipped with photoelectric imaging and intelligent target perception,are essential for reconnaissance and strike missions in complex and high-risk environments.They excel in information sharing,anti-jamming capabilities,and combat performance,making them critical for future warfare.However,varied perspectives in collaborative combat scenarios pose challenges to object detection,hindering traditional detection algorithms and reducing accuracy.Limited angle-prior data and sparse samples further complicate detection.This paper presents the Multi-View Collaborative Detection System,which tackles the challenges of multi-view object detection in collaborative combat scenarios.The system is designed to enhance multi-view image generation and detection algorithms,thereby improving the accuracy and efficiency of object detection across varying perspectives.First,an observation model for three-dimensional targets through line-of-sight angle transformation is constructed,and a multi-view image generation algorithm based on the Pix2Pix network is designed.For object detection,YOLOX is utilized,and a deep feature extraction network,BA-RepCSPDarknet,is developed to address challenges related to small target scale and feature extraction challenges.Additionally,a feature fusion network NS-PAFPN is developed to mitigate the issue of deep feature map information loss in UAV images.A visual attention module(BAM)is employed to manage appearance differences under varying angles,while a feature mapping module(DFM)prevents fine-grained feature loss.These advancements lead to the development of BA-YOLOX,a multi-view object detection network model suitable for drone platforms,enhancing accuracy and effectively targeting small objects.展开更多
In the past,the lightning strike risk assessment of wind farms mainly referred to the Lightning Protection Part 2:Risk Management(IEC 62305-2-2010)and the Lightning Protection of Wind Energy System(IEC 61400-24-2019)b...In the past,the lightning strike risk assessment of wind farms mainly referred to the Lightning Protection Part 2:Risk Management(IEC 62305-2-2010)and the Lightning Protection of Wind Energy System(IEC 61400-24-2019)based on protection angle method.In fact,the basic idea of the two is the same,that is,the source of the lightning fan is replaced by S1-S4 of the former lightning building with the latter ND-NDJ.According to the above method of wind farm evaluation,it has been proved that the practice can not achieve good results.Taking offshore wind farm as an example,this paper introduces a new method of establishing six evaluation indicators to determine the risk level according to the new technology and compliance principle of regional lightning protection(semi-circular method),which can be used for reference by wind farm technicians.展开更多
According to structure function and lightning damage of a cable car, a feasible method of lightning strike risk evaluation for a cable car was put forward based on the evaluation model and evaluation method in the sta...According to structure function and lightning damage of a cable car, a feasible method of lightning strike risk evaluation for a cable car was put forward based on the evaluation model and evaluation method in the standard IEC62305-2. According to the difference between common buildings and cable cars, problems of height non-uniformity of equivalent section caused by inclination of the cable car and diversity of lightning activity regularity caused by the large area were resolved, and expected annual average frequency of lightning strike was calculated using three dimensional graphic approach and regional lightning characteristic analysis. Based on different types of damage process and loss consequences, according to interception effect against lightning invasion of the lightning protection measures and the method of probability selection proposed in the standard, the probability of casu- alty caused by direct lightning strike in a cable car and a waiting area as well as probabilities of casualty caused by failure of electronic information systems were cal- culated.展开更多
Objective: To observe the risk factors of thrombosis in patients with obstructive sleep apnea hypopnea syndrome (OSAHS).Methods: From February 2001 to April 2003, 24 patients with moderate and severe OSAHS (OSAHS grou...Objective: To observe the risk factors of thrombosis in patients with obstructive sleep apnea hypopnea syndrome (OSAHS).Methods: From February 2001 to April 2003, 24 patients with moderate and severe OSAHS (OSAHS group) and 19 healthy adults (control group) were recruited. Their blood samples were drawn at 6∶00 and 16∶00 respectively for testing hemocrit, platelet aggregation (PAG), whole blood viscosity (WBV), prothrombin time (PT), activated partial thromboplastin time (APTT), plasma fibrinogen (Fng) and endothelin (ET).Results: There was a significantly higher hemocrit, WBV, Fng and ET as well as a significant shortening of PT and APTT at 6∶00 than that at 16∶00 in OSAHS group. However, there was no significant difference in all testing items between 6∶00 and 16∶00 in control group. The hemocrit, WBV, PAG, plasma Fng and ET were significantly higher, and PT and APTT were obviously shorter at 6∶00 in OSAHS group than those at 6∶00 in control group. A higher hemocrit, PAG, plasma Fng and ET, a longer PT and APTT were observed at 16∶00 in OSAHS group, compared with those at 16∶00 in control group.Conclusion: In OSAHS patients there were striking risk factors of thrombosis, which is more remarkable in the early morning than in the afternoon.展开更多
Non-alcoholic fatty liver disease(NAFLD)is a liver disease characterized by ectopic liver steatosis and steatosis.It is the most common chronic liver disease in China,and its incidence has gradually increased worldwid...Non-alcoholic fatty liver disease(NAFLD)is a liver disease characterized by ectopic liver steatosis and steatosis.It is the most common chronic liver disease in China,and its incidence has gradually increased worldwide,accompanied by the prevalence of obesity.In addition,NAFLD is associated with an increase in overall mortality,particularly in cardiovascular disease.So far,the mechanism of NAFLD is not very clear.This article aims to discuss the recent progress of various researches on NAFLD mechanism.展开更多
Founded in 1902 as the Transvaal Miners＇ Association, the South African Mine Workers＇ Union （MWU）, as it was renamed in 1913, rose to prominence as a militant union for white miners, especially during the turbulen...Founded in 1902 as the Transvaal Miners＇ Association, the South African Mine Workers＇ Union （MWU）, as it was renamed in 1913, rose to prominence as a militant union for white miners, especially during the turbulent years of industrial strife and bloody strike action in the first two decades of the 20th century. Since the election victory of the Pact government in 1924 a program of pro-white protectionist legislation was introduced. As South Africa＇s most prominent white trade union of the 20th century, the MWU therefore became renowned for defending job reservation in the mining industry. After 1948, it enjoyed the National Party government＇s support in this regard. However, skilled labor shortages and changing labor conditions in the 1970s forced the government to introduce labor reform. Job reservation was scrapped and black unions were officially recognized. These initiatives put the MWU on a confrontational path with the government and the union aligned itself with right-wing political resistance and protest. But, the altered political and economic South African realities after 1994 forced the MWU to rethink its strategies. By 2002, it had reinvented and transformed itself into Solidarity, adequately equipped for addressing the labor challenges and demands of a post-apartheid South Africa. This article, based on the author＇s research of the South African labor movement in the early 20th century, traces the historical development of the union and its influence on South African political and labor history.展开更多
A lightning arrester is used for electrical equipment protection against damage due to lightning strikes.One example of protected electrical equipment is electrical power transformer.If there is no lightning arrester ...A lightning arrester is used for electrical equipment protection against damage due to lightning strikes.One example of protected electrical equipment is electrical power transformer.If there is no lightning arrester installed to the transformer,when a lightning strike happens,it may receive a very high lightning overvoltage,which is certainly resulted in the transformer damage at its insulation.Usually,a lightning arrester specification data attached to a lightning arrester contains the rating data of the lightning arrester current and voltage.In the use of lightning arrester,the possibility of receiving multiple lightning strikes is not taken into account sometimes.In fact,in some places,the number of multiple strikes in short duration is quiet high in number.This condition makes the lightning arrester being stroked by multiple lightning strikes.Therefore,it may change the lightning arrester's properties,and then the arrester may not be able to provide good electrical equipment protection against lightning strike anymore.This condition will result in great loss to electrical companies and electrical consumers.Therefore,this research studied the effect of applying multiple lightning strikes to ZnO lightning arrester block.Every time a group of lightning impulse current is applied to the ZnO lightning arrester block,it is followed by the measuring of its 50 Hz voltage and current characteristic. The changing in the ZnO lightning arrester block 50 Hz characteristic then can be analyzed.It was found that by applying more numbers of lightning strikes which made the arrester becoming worse,even though,actually,the lightning impulse peak current was still under the rating of the lightning arrester current.In this case for a 5 kA,24 kV lightning arrester,even though the lightning impulse peak current flowing through the ZnO lightning arrester block was still 2500 A,the lightning arrester ZnO block had already been damaged.Having been damaged,an alternating current flowing through the damaged ZnO block was about 10000 times as much current flowing to the good one.The maximum of impulse energy absorbed by a ZnO block recorded was 334.7 J/cm^3.The damaged ZnO block should be replaced by a good one.展开更多
文摘Aircrafts damages caused by lightning strikes have been known since the early days of aviation.However,the physical effects on the aircraft structure are still being investigated.This work seeks to evaluate the lightning strike effects in the aluminum alloy 7075-T6.Samples were submitted to lightning strike simulation in laboratory and the damages evaluated through characterization techniques.Ultrasound and profilometry tests have shown material loss to 0.272 mm depth in the damaged region.In addition,it was detected the material accumulation occurrence in the damage vicinity of the region.Below the damage,it was found a region where metallurgical changes were identified.The tensile and microhardness tests results have shown reduction in the percentage elongation and hardness increasing in the material affected by lightning.These results are corroborated by the X-Ray Diffraction(XRD)and Rietveld Method(red line)that indicated an increasing in dislocation density and micro-deformation in the material matrix.Optical microscopy results have shown the presence of microcracks on the normal and cross-section surface of the samples damaged.The Energy Dispersive X-Ray Spectroscopy(EDXS)and Electron Backscattered Diffraction Test(EBSD)found coarse intermetallic phases and precipitates compounds with dimensions greater than 1 lm in length.They were responsible for nucleation of the microcracks that propagate along the material grain boundaries.
基金funded by the Natural Science Foundation of China(Grant No.42077435)。
文摘This article presents a mathematical model for simulating the mechanical behaviour of lightning strikes and analysing the resulting damage to the soil.This article focuses on the electro-thermal effect and seepage caused by lightning strikes in particular.Then,a numerical model based on the conservation laws of momentum,mass and energy is developed for soil subjected to lightning strikes.Comparisons to field observations and theoretical calculations are used to demonstrate the efficacy and accuracy of numerical simulations.The findings demonstrate that lightning strikes can cause soils to experience both seepage force and heat stress.Under the calculative condition of this article:by increasing the intrinsic permeability of the soil,k_(p)(≥10^(-10)m^(2)),the seepage force can be effectively reduced,hence reducing the risk of lightning strikes;improving the electrical conductivity of the soil β(≥10^(-1) S/m^(2))and lowering its thermal expansion coefficient(≤10^(-6)K^(-1))can greatly reduce the damage caused by lightning strikes to the soil.The preceding investigations demonstrate that the suggested model is capable of evaluating mechanical damage caused by lightning in the soil,and the findings contribute to a better understanding of soil mechanical response to lightning strikes.
基金supported by Natural Science Foundation of China (No.11472225)
文摘In this paper, a method to design bird-strike-resistant aircraft structures is presented and illustrated through examples. The focus is on bird strike experiments and simulations. The explicit finite element software PAM-CRASH is employed to conduct bird strike simulations, and a coupled Smooth Particles Hydrodynamic（SPH） and Finite Element（FE） method is used to simulate the interaction between a bird and a target structure. The SPH method is explained, and an SPH bird model is established. Constitutive models for various structural materials, such as aluminum alloys, composite materials, honeycomb, and foam materials that are used in aircraft structures,are presented, and model parameters are identified by conducting various material tests. Good agreements between simulation results and experimental data suggest that the numerical model is capable of predicting the dynamic responses of various aircraft structures under a bird strike,and numerical simulation can be used as a tool to design bird-strike-resistant aircraft structures.
基金Supported by Lightning Multi-pulse Intelligent Monitoring System Optimization Technology Project of Guangdong Yuedian Dianbai Hot Water Wind Farm(SFC/DBW-Z-FW-23-006).
文摘Since ancient times,lightning disasters have undoubtedly been an unstoppable threat to humanity.During thunderstorms,lightning often damages objects on the ground,such as buildings and structures.Since Franklin invented the lightning rod in 1752,lightning rods have been used worldwide to prevent direct lightning strikes in various fields such as high-voltage power transmission lines,outdoor chemical sites,highways,land and sea wind farms,and forest lightning fire protection.It has been proven that lightning accidents still occur frequently in places where lightning rods are installed and the protective angle method is used.In order to further study the protective effect of lightning rods and identify the shortcomings of lightning rod protection,negative lightning strikes are taken as the research object,to analyze the limitations of lightning rods in preventing direct lightning strikes from the working principle of lightning rods.
基金the National Natural Science Foundation of China(No.51467002)Special Projects for Innovation-driven Development(No.2018AA03001Y).
文摘Traditional lightning protection measures can not solve the problem of superimposed lightning strikes.This paper presents a compressing arc extinguishing lightning protection device,which can solve the problem of superimposed lightning strikes.This device can extinguish the power frequency continuous current arc quickly in 1-2 ms.It is far less than the response time of relay protection,which can avoid lightning trips and improve the reliability of power supply.The computer simulation and engineering practice show that the compressing arc extinguishing device has good protection effect on superimposed lightning strikes.
基金the Educational Department of Liaoning Province(20081220)
文摘Presented the concept of the natural support strength.The natural support strength,the strike sill,the multifunction retractors (developed by the author) and etc.were used with the technical measures to change the passive support to the initiative support, and the soft rock entry was supported.And its process is simple and less equipment is needed,and the cost is low and the advance rate is high,which can meet the require- ments of actual mining.It solves many support difficult problems.
文摘Suffering from rampant piracy, China's film, music and software industries look to special measures to counter attack Watching out for pirates has taken on an entirely new meaning for Fang Yunyun. No, she's not looking through a telescope for a ship loaded with mean-looking sailors brandishing swords. Fang is an executive at an audio-video company in Beijing, and her anti-piracy watch means being on the
文摘IN 1987, the Fourth International Music Festival was held in Belgrade. When the Chinese song "The Green Leaves’s Love for the Root" was reverberating through the hall, the whole audience held their breath, listening attentively. This song not only moved all the people present but its approach of mode and the smooth and lyric melody left a deep impression on the adjudicators. As a result, this song won the third prize, the highest award any Chinese pop song had ever won at any international contest before 1987. The composer of this song is Gu Jianfen. Since the early 1980s, Gu Jianfen’s compositions have won her various awards in Chinese song contests. In 1985, five of her compositions won "Prize for Songs Favored
文摘Until recently,the study of language and meaning of cartoons,the media discourses they generate,and their analysis as a creative means of exploring meaning-making processes as semiotic resources have not received much scholarly attention in Nigeria.Although cartoons that involve the use of satire and humour as visual representations of reality have gained prominence across many media platforms in Nigeria,only a few scholars have examined this from a social semiotics perspective.This has created a gap in the literature,thus creating room for a para-digm shift in the field of social semiotics.This study explores the semiotics of car-toons in selected Nigerian newspapers to examine the meaning-making resources employed in the visual representation of ASUU strikes in Nigeria.The study,there-fore,examines how cartoonists manipulate symbols,signs,and other semiotic resources to convey specific meanings through visual and textual representations.The study adopts a qualitative research design;data comprising cartoons sourced from selected Vanguard Newspapers and websites are analyzed using Kress and Van Leeuwen's visual semiotics and interpreted from the standpoints of Halliday's Systematic Functional Linguistics(SFL)approach and O'Halloran's position on metaphorical constructions of meaning.Here,metaphorical manipulation and rep-resentation of visual elements in the selected cartoons are interrogated.Findings from the study show the use of semiotic resources in the portrayer of reality in the context of the seemingly intractable ASUU strikes and their consequences on aca-demic activities in Nigeria.This scholarly intervention deserves attention as it significantly contributes to the field of social semiotics through its visual represen-tation in portraying challenges faced by the educational systems in Nigeria vis-a-vis poorgovernment funding.
文摘0n October 14,the China National Computer Virus Emergency Response Center,the National Engineering Laboratory for Computer Virus Prevention Technology and 360 Digital Security Group jointly released a report,Volt Typhoon III:A Cyber Espionage and Disinformation Campaign Conducted by U.S.Government Agencies,to unveil the U.S.-staged so-called"Volt Typhoon"farce.This is the third strike China conducted in 2024 on the Washingtonstyle play script of Catch Me if You Can.
文摘In 1891,a New York surgeon named William Coley injected cancer patients with live bacteria,observing with fascination as some tumors shrank amid raging fevers.His crude experiments-later deemed reckless-nonetheless revealed a tantalizing truth:The immune system,when properly provoked,could attack cancer.Over a century later,researchers have transformed this observation into a precision strike force.
基金supported by the Natural Science Foundation of China,Grant No.62103052.
文摘Drone swarm systems,equipped with photoelectric imaging and intelligent target perception,are essential for reconnaissance and strike missions in complex and high-risk environments.They excel in information sharing,anti-jamming capabilities,and combat performance,making them critical for future warfare.However,varied perspectives in collaborative combat scenarios pose challenges to object detection,hindering traditional detection algorithms and reducing accuracy.Limited angle-prior data and sparse samples further complicate detection.This paper presents the Multi-View Collaborative Detection System,which tackles the challenges of multi-view object detection in collaborative combat scenarios.The system is designed to enhance multi-view image generation and detection algorithms,thereby improving the accuracy and efficiency of object detection across varying perspectives.First,an observation model for three-dimensional targets through line-of-sight angle transformation is constructed,and a multi-view image generation algorithm based on the Pix2Pix network is designed.For object detection,YOLOX is utilized,and a deep feature extraction network,BA-RepCSPDarknet,is developed to address challenges related to small target scale and feature extraction challenges.Additionally,a feature fusion network NS-PAFPN is developed to mitigate the issue of deep feature map information loss in UAV images.A visual attention module(BAM)is employed to manage appearance differences under varying angles,while a feature mapping module(DFM)prevents fine-grained feature loss.These advancements lead to the development of BA-YOLOX,a multi-view object detection network model suitable for drone platforms,enhancing accuracy and effectively targeting small objects.
基金Supported by Research on Key Technologies of Lightning Intelligent Protection System for Guangdong Energy Hehe Sea Wind Farm(SFC/QZW-ZX-XF-24-020).
文摘In the past,the lightning strike risk assessment of wind farms mainly referred to the Lightning Protection Part 2:Risk Management(IEC 62305-2-2010)and the Lightning Protection of Wind Energy System(IEC 61400-24-2019)based on protection angle method.In fact,the basic idea of the two is the same,that is,the source of the lightning fan is replaced by S1-S4 of the former lightning building with the latter ND-NDJ.According to the above method of wind farm evaluation,it has been proved that the practice can not achieve good results.Taking offshore wind farm as an example,this paper introduces a new method of establishing six evaluation indicators to determine the risk level according to the new technology and compliance principle of regional lightning protection(semi-circular method),which can be used for reference by wind farm technicians.
基金Supported by the Scientific Research Project of Hebei Meteorological Bureau in 2014(14ky20)~~
文摘According to structure function and lightning damage of a cable car, a feasible method of lightning strike risk evaluation for a cable car was put forward based on the evaluation model and evaluation method in the standard IEC62305-2. According to the difference between common buildings and cable cars, problems of height non-uniformity of equivalent section caused by inclination of the cable car and diversity of lightning activity regularity caused by the large area were resolved, and expected annual average frequency of lightning strike was calculated using three dimensional graphic approach and regional lightning characteristic analysis. Based on different types of damage process and loss consequences, according to interception effect against lightning invasion of the lightning protection measures and the method of probability selection proposed in the standard, the probability of casu- alty caused by direct lightning strike in a cable car and a waiting area as well as probabilities of casualty caused by failure of electronic information systems were cal- culated.
文摘Objective: To observe the risk factors of thrombosis in patients with obstructive sleep apnea hypopnea syndrome (OSAHS).Methods: From February 2001 to April 2003, 24 patients with moderate and severe OSAHS (OSAHS group) and 19 healthy adults (control group) were recruited. Their blood samples were drawn at 6∶00 and 16∶00 respectively for testing hemocrit, platelet aggregation (PAG), whole blood viscosity (WBV), prothrombin time (PT), activated partial thromboplastin time (APTT), plasma fibrinogen (Fng) and endothelin (ET).Results: There was a significantly higher hemocrit, WBV, Fng and ET as well as a significant shortening of PT and APTT at 6∶00 than that at 16∶00 in OSAHS group. However, there was no significant difference in all testing items between 6∶00 and 16∶00 in control group. The hemocrit, WBV, PAG, plasma Fng and ET were significantly higher, and PT and APTT were obviously shorter at 6∶00 in OSAHS group than those at 6∶00 in control group. A higher hemocrit, PAG, plasma Fng and ET, a longer PT and APTT were observed at 16∶00 in OSAHS group, compared with those at 16∶00 in control group.Conclusion: In OSAHS patients there were striking risk factors of thrombosis, which is more remarkable in the early morning than in the afternoon.
基金National natural science foundation of China(No.81774132)。
文摘Non-alcoholic fatty liver disease(NAFLD)is a liver disease characterized by ectopic liver steatosis and steatosis.It is the most common chronic liver disease in China,and its incidence has gradually increased worldwide,accompanied by the prevalence of obesity.In addition,NAFLD is associated with an increase in overall mortality,particularly in cardiovascular disease.So far,the mechanism of NAFLD is not very clear.This article aims to discuss the recent progress of various researches on NAFLD mechanism.
文摘Founded in 1902 as the Transvaal Miners＇ Association, the South African Mine Workers＇ Union （MWU）, as it was renamed in 1913, rose to prominence as a militant union for white miners, especially during the turbulent years of industrial strife and bloody strike action in the first two decades of the 20th century. Since the election victory of the Pact government in 1924 a program of pro-white protectionist legislation was introduced. As South Africa＇s most prominent white trade union of the 20th century, the MWU therefore became renowned for defending job reservation in the mining industry. After 1948, it enjoyed the National Party government＇s support in this regard. However, skilled labor shortages and changing labor conditions in the 1970s forced the government to introduce labor reform. Job reservation was scrapped and black unions were officially recognized. These initiatives put the MWU on a confrontational path with the government and the union aligned itself with right-wing political resistance and protest. But, the altered political and economic South African realities after 1994 forced the MWU to rethink its strategies. By 2002, it had reinvented and transformed itself into Solidarity, adequately equipped for addressing the labor challenges and demands of a post-apartheid South Africa. This article, based on the author＇s research of the South African labor movement in the early 20th century, traces the historical development of the union and its influence on South African political and labor history.
文摘A lightning arrester is used for electrical equipment protection against damage due to lightning strikes.One example of protected electrical equipment is electrical power transformer.If there is no lightning arrester installed to the transformer,when a lightning strike happens,it may receive a very high lightning overvoltage,which is certainly resulted in the transformer damage at its insulation.Usually,a lightning arrester specification data attached to a lightning arrester contains the rating data of the lightning arrester current and voltage.In the use of lightning arrester,the possibility of receiving multiple lightning strikes is not taken into account sometimes.In fact,in some places,the number of multiple strikes in short duration is quiet high in number.This condition makes the lightning arrester being stroked by multiple lightning strikes.Therefore,it may change the lightning arrester's properties,and then the arrester may not be able to provide good electrical equipment protection against lightning strike anymore.This condition will result in great loss to electrical companies and electrical consumers.Therefore,this research studied the effect of applying multiple lightning strikes to ZnO lightning arrester block.Every time a group of lightning impulse current is applied to the ZnO lightning arrester block,it is followed by the measuring of its 50 Hz voltage and current characteristic. The changing in the ZnO lightning arrester block 50 Hz characteristic then can be analyzed.It was found that by applying more numbers of lightning strikes which made the arrester becoming worse,even though,actually,the lightning impulse peak current was still under the rating of the lightning arrester current.In this case for a 5 kA,24 kV lightning arrester,even though the lightning impulse peak current flowing through the ZnO lightning arrester block was still 2500 A,the lightning arrester ZnO block had already been damaged.Having been damaged,an alternating current flowing through the damaged ZnO block was about 10000 times as much current flowing to the good one.The maximum of impulse energy absorbed by a ZnO block recorded was 334.7 J/cm^3.The damaged ZnO block should be replaced by a good one.
