Optical spectroscopy has been intensively studied for cancer management in the past two decades.This review paper first introduces the background of optical spectroscopy for cancer management,which includes the advant...Optical spectroscopy has been intensively studied for cancer management in the past two decades.This review paper first introduces the background of optical spectroscopy for cancer management,which includes the advantages of optical techniques compared to other established techniques,the principle of optical spectroscopy and the typical setup of instrumentation.Then the recent progress in optical spectroscopy for cancer diagnosis in the following organs is reviewed:the brain,breast,cervix,lung,stomach,colon,prostate and the skin.Reviewed papers were selected from the PubMed database with keywords combining the terms of individual optical spectroscopy techniques and cancers.The primary focus is on the in vivo applications of optical spectroscopy in clinical studies.Ex vivo studies are also included for some organs to highlight special applications or when there are few in vivo results in the literature.Practical considerations of applying optical spectroscopy in clinical settings such as the speed,cost,complexity of operation,accuracy and clinical value are discussed.A few commercially available clinical instruments that are based on optical spectroscopy techniques are presented.Finally several technical challenges and standard issues are discussed and firm conclusions are made.展开更多
Since the opening-up policy was carried out in 1979, every facility of social modernized construction has developed at high speed; meanwhile, the need of English is increased year by year. The occasion and scope of us...Since the opening-up policy was carried out in 1979, every facility of social modernized construction has developed at high speed; meanwhile, the need of English is increased year by year. The occasion and scope of using it are expanded with the communications among countries. Therefore, English has become the generally international language in our country; in particular, translation plays an important and irreplaceable part in English to convey information. This paper aims to introduce the contrasts of English sentences and Chinese sentences and discuss some skills of translating each other. Though it is not complete and authoritative, yet it may help some people to understand the differences between two languages and to grasp some practical skills.展开更多
People make comparison and contrasts everyday,though they may not be aware of it. Comparison and contrast are ma jor methods to develop a piece of exposition. This paper mainly interprets the effective use of contrast...People make comparison and contrasts everyday,though they may not be aware of it. Comparison and contrast are ma jor methods to develop a piece of exposition. This paper mainly interprets the effective use of contrasts in The Virtues of Growing Older and explores the language art of an exposition.展开更多
In Beyond the Horizon,a three-act play,Eugene O'Neill successfully employs the techinique of contrast,namely,contrasts between different characters,between indoor and outdoor settings,and between seasons,which hel...In Beyond the Horizon,a three-act play,Eugene O'Neill successfully employs the techinique of contrast,namely,contrasts between different characters,between indoor and outdoor settings,and between seasons,which help to acquire rich symbolic meaning and intensify the tragic sense of the play.展开更多
This paper aims at examining the perception of English tense and lax vowel contrasts by testing an identification task of CVC syllables with different manipulated durations in Chinese learners of English.This can prov...This paper aims at examining the perception of English tense and lax vowel contrasts by testing an identification task of CVC syllables with different manipulated durations in Chinese learners of English.This can provide some empirical evidence for English as a second language teachers in teaching second language pronunciation.展开更多
The important effects of local land-sea thermodynamic contrast between the South China Sea (SCS) and Indochina Peninsula on SCS summer monsoon onset are preliminarily studied by using two sets of SSTA tests and two id...The important effects of local land-sea thermodynamic contrast between the South China Sea (SCS) and Indochina Peninsula on SCS summer monsoon onset are preliminarily studied by using two sets of SSTA tests and two ideal tests in s-p regional climate model. The result shows that warm SST in the SCS in winter and spring is favorable for the formation of monsoon circulation throughout all levels of the atmosphere over the sea, which hastens the onset of SCS summer monsoon. The effects of cold SST are generally the opposite. The local land-sea contrast in the SCS is one of the possible reasons for SCS summer monsoon onset. Superposed upon large-scale land-sea thermodynamic differences, it facilitates the formation of out-breaking onset characteristics of SCS summer monsoon in the SCS area.展开更多
Contrastive linguistics belongs to a branch of linguistics.It studies two or more languages synchronically.However,lexicology is the study of lexical items of a language.An English sentence or a Chinese sentence forme...Contrastive linguistics belongs to a branch of linguistics.It studies two or more languages synchronically.However,lexicology is the study of lexical items of a language.An English sentence or a Chinese sentence formed based on words and clauses.Because of differences in Cultures,the lexical meanings between English and Chinese differ in many aspects,such as motivation of words and sense relationships.This paper is a brief review that just likes a book report,mainly based on the book Contrastive Linguistics,of lexico-semantic contrasts between English and Chinese,illustrated with several examples in both English and Chinese.展开更多
AIM: To assess and compare the image quality of 4% sorbitol and diluted iodine 2%(positive oral contrast agent) in abdomino-pelvic multi-detector computed tomography.METHODS: Two-hundred patients, referred to the Radi...AIM: To assess and compare the image quality of 4% sorbitol and diluted iodine 2%(positive oral contrast agent) in abdomino-pelvic multi-detector computed tomography.METHODS: Two-hundred patients, referred to the Radiology Department of a central educational hospital for multi-detector row abdominal-pelvic computed tomography, were randomly divided into two groups: the first group received 1500 m L of 4% sorbitol solution as a neutral contrast agent, while in the second group 1500 m L of meglumin solution as a positive contrast agent was administered in a one-way randomized prospective study. The results were independently reviewed by two radiologists. Luminal distension and mural thickness and mucosal enhancement were compared between the two groups. Statistical analysis of the results was performed by Statistical Package for the Social Sciences software version 16 and the Mann-Whitney test at a confidence level of 95%. RESULTS: Use of neutral oral contrast agent significantly improved visualization of the small bowel wall thickness and mural appearance in comparison with administration of positive contrast agent(P < 0.01). In patients who received sorbitol, the small bowel showed better distention compared with those who received iodine solution as a positive contrast agent(P < 0.05). CONCLUSION: The results of the study demonstrated that oral administration of sorbitol solution allows better luminal distention and visualization of mural features than iodine solution as a positive contrast agent.展开更多
The P receiver function includes P-to-SV converted phases and multiple reverberations of the discontinuities in the crust and mantle.The time of these phases is related to the crustal thickness and vp/vs ratio,and the...The P receiver function includes P-to-SV converted phases and multiple reverberations of the discontinuities in the crust and mantle.The time of these phases is related to the crustal thickness and vp/vs ratio,and the amplitude of these phases is mainly controlled by the velocity and density contrast of interfaces.By using H-κstacking method,this work estimated the crustal thickness and vP/vS ratio beneath the stations in the Guangdong province of South China.The velocity and density contrast(δβ-δρ)scanning stacking algorithm of the receiver function is applied to constrain the velocity and density contrast of the Moho in Guangdong province.This work analyzed the results of the crustal thickness,vp/vS ratio,and the velocity and density contrasts of Moho.The results indicate that the velocity contrast is higher beneath Yangjiang area in western Guangdong province and Nanao area in eastern Guangdong,which has a strong correlation with the distribution of geothermal springs in local areas and the characteristics of high heat flow.The velocity contrast of Moho has also a good correlation with the vP/vS ratio and the crustal thickness,which indicates that there is a strong material composition contrasts of the Moho in the study area.Velocity and density contrasts of Moho in some local area(such as western Guangdong)are somewhat consistent with the seismic activities.展开更多
In this study, it was shown that, same comparisons can be made by using contrast coefficients instead of Dunnett＇s test in the experiments with control groups. It was also shown that, in situations with an ordinal sc...In this study, it was shown that, same comparisons can be made by using contrast coefficients instead of Dunnett＇s test in the experiments with control groups. It was also shown that, in situations with an ordinal scale and equal spacing quantitative grouping, a trend investigation could be done by contrast coefficients. For this purpose, a small part of the data from a TUBITAK project in the Soil Science Department, Agriculture Faculty, Kahramanmaras Sutcu Imam University, was used with permission. The soils were absorbed to natural zeolite in concentration of 0, 2.5, 5 and 10 mg/kg, and after two years, the available Zinc （Zn） amounts in the soil were analyzed. As a result, in both Dunnett＇s test and contrast methods, the Zn amounts in control and 2.5 mg/kg concentration groups were found similar （P 〉 0.01）; but were different （P 〈 0.01） between control and 5 mg/kg concentration groups, and control and 10 mg/kg concentration groups. Furthermore, when orthogonal polynomial contrast coefficients were investigated, linear effects were found significant （P 〈 0.01） and cubic effects were obtained significant （P 〈 0.05）, but quadratic effect was obtained insignificant （P 〉 0.05）.展开更多
Go Down, Moses is one of William Faulkner's famous novels. It consists of seven stories, most of which have been published earlier as magazine stories. When it first gets published, many reviewers regard it as a c...Go Down, Moses is one of William Faulkner's famous novels. It consists of seven stories, most of which have been published earlier as magazine stories. When it first gets published, many reviewers regard it as a collection of stories, due to its seven loosely jointed stories with their seemingly irrelevant plots and themes. Nowadays, critics take a as a completed novel with different contrastive characters which make the stories more attractive and deepen the plots and themes.展开更多
As climate change intensifies,prolonged extreme droughts are becoming a dominant force shaping terrestrial ecosystems(Smith et al.,2024).While it is well established that drought reduces grassland productivity,questio...As climate change intensifies,prolonged extreme droughts are becoming a dominant force shaping terrestrial ecosystems(Smith et al.,2024).While it is well established that drought reduces grassland productivity,questions remain about whether these impacts accumulate or stabilize over time,and whether responses vary across global biomes.A groundbreaking study by Yu et al.(2025)addresses these gaps by implementing a rare,standardized multi-year drought experiment across two continents,uncovering profound differences in the ecological trajectories of Eurasian and North American grasslands.展开更多
Drill string vibration during drilling plays a vital and potentially decisive role in maintaining wellbore stability,as repeated impacts may lead to fatigue and borehole collapse.While drilling through geological laye...Drill string vibration during drilling plays a vital and potentially decisive role in maintaining wellbore stability,as repeated impacts may lead to fatigue and borehole collapse.While drilling through geological layers,a material contrast may act as a localization point for wellbore damage.The hypothesis tested in this paper is that wellbore instability is focused on the boundary between the layers and that mechanical contrasts accelerate the wellbore collapse.In this study,an elastic-plastic damage model was employed to investigate the effects of repeated mechanical impacts on wellbore stability.A 2-dimensional(2D)model of a wellbore surrounded by contrasting materials was developed,and the accumulated damage caused by repeated lateral impacts was monitored.It was found that damage develops not only around the wall of the wellbore but also along the material boundaries.A sensitivity analysis was carried out to identify the impact of contrasts in both elastic(Young's modulus and Poisson's ratio)and plastic(cohesion,friction angle,and dilation angle)parameters between layers.Four damage patterns were identifiedin the simulated models.The results also suggested that the number of impacts required to reach the critical damage was highly affected by the contrast in elastic parameters,while cohesion and friction angle contrasts had a lesser effect.Additionally,increasing the contrast in the dilation angle localized the damage,thus reducing the number of impacts required to trigger wellbore failure.展开更多
In high-intensity electromagnetic warfare,radar systems are persistently subjected to multi-jammer attacks,including potentially novel unknown jamming types that may emerge exclusively under wartime conditions.These j...In high-intensity electromagnetic warfare,radar systems are persistently subjected to multi-jammer attacks,including potentially novel unknown jamming types that may emerge exclusively under wartime conditions.These jamming signals severely degrade radar detection performance.Precise recognition of these unknown and compound jamming signals is critical to enhancing the anti-jamming capabilities and overall reliability of radar systems.To address this challenge,this article proposes a novel open-set compound jamming cognition(OSCJC)method.The proposed method employs a detection-classification dual-network architecture,which not only overcomes the false alarm and misdetection issues of traditional closed-set recognition methods when dealing with unknown jamming but also effectively addresses the performance bottleneck of existing open-set recognition techniques focusing on single jamming scenarios in compound jamming environments.To achieve unknown jamming detection,we first employ a consistency labeling strategy to train the detection network using diverse known jamming samples.This strategy enables the network to acquire highly generalizable jamming features,thereby accurately localizing candidate regions for individual jamming components within compound jamming.Subsequently,we introduce contrastive learning to optimize the classification network,significantly enhancing both intra-class clustering and inter-class separability in the jamming feature space.This method not only improves the recognition accuracy of the classification network for known jamming types but also enhances its sensitivity to unknown jamming types.Simulations and experimental data are used to verify the effectiveness of the proposed OSCJC method.Compared with the state-of-the-art open-set recognition methods,the proposed method demonstrates superior recognition accuracy and enhanced environmental adaptability.展开更多
To address the issue of scarce labeled samples and operational condition variations that degrade the accuracy of fault diagnosis models in variable-condition gearbox fault diagnosis,this paper proposes a semi-supervis...To address the issue of scarce labeled samples and operational condition variations that degrade the accuracy of fault diagnosis models in variable-condition gearbox fault diagnosis,this paper proposes a semi-supervised masked contrastive learning and domain adaptation(SSMCL-DA)method for gearbox fault diagnosis under variable conditions.Initially,during the unsupervised pre-training phase,a dual signal augmentation strategy is devised,which simultaneously applies random masking in the time domain and random scaling in the frequency domain to unlabeled samples,thereby constructing more challenging positive sample pairs to guide the encoder in learning intrinsic features robust to condition variations.Subsequently,a ConvNeXt-Transformer hybrid architecture is employed,integrating the superior local detail modeling capacity of ConvNeXt with the robust global perception capability of Transformer to enhance feature extraction in complex scenarios.Thereafter,a contrastive learning model is constructed with the optimization objective of maximizing feature similarity across different masked instances of the same sample,enabling the extraction of consistent features from multiple masked perspectives and reducing reliance on labeled data.In the final supervised fine-tuning phase,a multi-scale attention mechanism is incorporated for feature rectification,and a domain adaptation module combining Local Maximum Mean Discrepancy(LMMD)with adversarial learning is proposed.This module embodies a dual mechanism:LMMD facilitates fine-grained class-conditional alignment,compelling features of identical fault classes to converge across varying conditions,while the domain discriminator utilizes adversarial training to guide the feature extractor toward learning domain-invariant features.Working in concert,they markedly diminish feature distribution discrepancies induced by changes in load,rotational speed,and other factors,thereby boosting the model’s adaptability to cross-condition scenarios.Experimental evaluations on the WT planetary gearbox dataset and the Case Western Reserve University(CWRU)bearing dataset demonstrate that the SSMCL-DA model effectively identifies multiple fault classes in gearboxes,with diagnostic performance substantially surpassing that of conventional methods.Under cross-condition scenarios,the model attains fault diagnosis accuracies of 99.21%for the WT planetary gearbox and 99.86%for the bearings,respectively.Furthermore,the model exhibits stable generalization capability in cross-device settings.展开更多
This study aims to develop a novel,cost-effective method for fabricating silicone vascular phantoms(SVPs)using"chewy candy"as a dissolvable core material.The study explores the feasibility of using chewy can...This study aims to develop a novel,cost-effective method for fabricating silicone vascular phantoms(SVPs)using"chewy candy"as a dissolvable core material.The study explores the feasibility of using chewy candy to create detailed and intricate vascular models for clinical applications.The chewy candy,an amorphous material,was manually extruded to form vascular models of varying diameters.These models were embedded in a silicone mixture,which was then cured.The chewy candy was subsequently dissolved,leaving behind hollow silicone vascular channels.The SVPs were evaluated for their morphological accuracy and functionality through laser speckle contrast imaging.The SVPs successfully replicated vascular channels with consistent diameters,demonstrating minimal variation across different regions.Functional evaluation using laser speckle contrast imaging revealed distinct flow dynamics in Y-shaped and H-shaped SVPs,highlighting the potential for these phantoms to simulate realistic fluid dynamics in vascular systems.This study presents a simple,time-saving,and innovative approach to fabricating complex 3D SVPs using chewy candy.This method offers a viable alternative to traditional fabrication techniques,with potential applications in various biomedical fields.展开更多
文摘Optical spectroscopy has been intensively studied for cancer management in the past two decades.This review paper first introduces the background of optical spectroscopy for cancer management,which includes the advantages of optical techniques compared to other established techniques,the principle of optical spectroscopy and the typical setup of instrumentation.Then the recent progress in optical spectroscopy for cancer diagnosis in the following organs is reviewed:the brain,breast,cervix,lung,stomach,colon,prostate and the skin.Reviewed papers were selected from the PubMed database with keywords combining the terms of individual optical spectroscopy techniques and cancers.The primary focus is on the in vivo applications of optical spectroscopy in clinical studies.Ex vivo studies are also included for some organs to highlight special applications or when there are few in vivo results in the literature.Practical considerations of applying optical spectroscopy in clinical settings such as the speed,cost,complexity of operation,accuracy and clinical value are discussed.A few commercially available clinical instruments that are based on optical spectroscopy techniques are presented.Finally several technical challenges and standard issues are discussed and firm conclusions are made.
文摘Since the opening-up policy was carried out in 1979, every facility of social modernized construction has developed at high speed; meanwhile, the need of English is increased year by year. The occasion and scope of using it are expanded with the communications among countries. Therefore, English has become the generally international language in our country; in particular, translation plays an important and irreplaceable part in English to convey information. This paper aims to introduce the contrasts of English sentences and Chinese sentences and discuss some skills of translating each other. Though it is not complete and authoritative, yet it may help some people to understand the differences between two languages and to grasp some practical skills.
文摘People make comparison and contrasts everyday,though they may not be aware of it. Comparison and contrast are ma jor methods to develop a piece of exposition. This paper mainly interprets the effective use of contrasts in The Virtues of Growing Older and explores the language art of an exposition.
文摘In Beyond the Horizon,a three-act play,Eugene O'Neill successfully employs the techinique of contrast,namely,contrasts between different characters,between indoor and outdoor settings,and between seasons,which help to acquire rich symbolic meaning and intensify the tragic sense of the play.
文摘This paper aims at examining the perception of English tense and lax vowel contrasts by testing an identification task of CVC syllables with different manipulated durations in Chinese learners of English.This can provide some empirical evidence for English as a second language teachers in teaching second language pronunciation.
基金National Natural Science Foundation of China (40175021 40233037)
文摘The important effects of local land-sea thermodynamic contrast between the South China Sea (SCS) and Indochina Peninsula on SCS summer monsoon onset are preliminarily studied by using two sets of SSTA tests and two ideal tests in s-p regional climate model. The result shows that warm SST in the SCS in winter and spring is favorable for the formation of monsoon circulation throughout all levels of the atmosphere over the sea, which hastens the onset of SCS summer monsoon. The effects of cold SST are generally the opposite. The local land-sea contrast in the SCS is one of the possible reasons for SCS summer monsoon onset. Superposed upon large-scale land-sea thermodynamic differences, it facilitates the formation of out-breaking onset characteristics of SCS summer monsoon in the SCS area.
文摘Contrastive linguistics belongs to a branch of linguistics.It studies two or more languages synchronically.However,lexicology is the study of lexical items of a language.An English sentence or a Chinese sentence formed based on words and clauses.Because of differences in Cultures,the lexical meanings between English and Chinese differ in many aspects,such as motivation of words and sense relationships.This paper is a brief review that just likes a book report,mainly based on the book Contrastive Linguistics,of lexico-semantic contrasts between English and Chinese,illustrated with several examples in both English and Chinese.
文摘AIM: To assess and compare the image quality of 4% sorbitol and diluted iodine 2%(positive oral contrast agent) in abdomino-pelvic multi-detector computed tomography.METHODS: Two-hundred patients, referred to the Radiology Department of a central educational hospital for multi-detector row abdominal-pelvic computed tomography, were randomly divided into two groups: the first group received 1500 m L of 4% sorbitol solution as a neutral contrast agent, while in the second group 1500 m L of meglumin solution as a positive contrast agent was administered in a one-way randomized prospective study. The results were independently reviewed by two radiologists. Luminal distension and mural thickness and mucosal enhancement were compared between the two groups. Statistical analysis of the results was performed by Statistical Package for the Social Sciences software version 16 and the Mann-Whitney test at a confidence level of 95%. RESULTS: Use of neutral oral contrast agent significantly improved visualization of the small bowel wall thickness and mural appearance in comparison with administration of positive contrast agent(P < 0.01). In patients who received sorbitol, the small bowel showed better distention compared with those who received iodine solution as a positive contrast agent(P < 0.05). CONCLUSION: The results of the study demonstrated that oral administration of sorbitol solution allows better luminal distention and visualization of mural features than iodine solution as a positive contrast agent.
基金the National Key R&D Program of China(No.2017YFC1500100)National Natural Science Foundation of China(Nos.U1701641,41874052,41730211 and 41774049)+5 种基金Guangdong Province Introduced Innovative R&D Team(Nos.2017ZT07Z066 and 2016ZT06N331)Guangdong Science and Technology Plan Project(No.2017B030314082)Combination Project with Monitoring,Prediction and Scientific Research of Earthquake Technology,CEA(No.3JH-201901051)Seismic Regime Tracking Project of CEA(No.2020010111)Some figures were plotted with Generic Mapping Tools(Wessel and Smith,1995)The authors sincerely acknowledge the anonymous reviewers and journal editors for their help,support,checking and helpful comments to the manuscript.
文摘The P receiver function includes P-to-SV converted phases and multiple reverberations of the discontinuities in the crust and mantle.The time of these phases is related to the crustal thickness and vp/vs ratio,and the amplitude of these phases is mainly controlled by the velocity and density contrast of interfaces.By using H-κstacking method,this work estimated the crustal thickness and vP/vS ratio beneath the stations in the Guangdong province of South China.The velocity and density contrast(δβ-δρ)scanning stacking algorithm of the receiver function is applied to constrain the velocity and density contrast of the Moho in Guangdong province.This work analyzed the results of the crustal thickness,vp/vS ratio,and the velocity and density contrasts of Moho.The results indicate that the velocity contrast is higher beneath Yangjiang area in western Guangdong province and Nanao area in eastern Guangdong,which has a strong correlation with the distribution of geothermal springs in local areas and the characteristics of high heat flow.The velocity contrast of Moho has also a good correlation with the vP/vS ratio and the crustal thickness,which indicates that there is a strong material composition contrasts of the Moho in the study area.Velocity and density contrasts of Moho in some local area(such as western Guangdong)are somewhat consistent with the seismic activities.
文摘In this study, it was shown that, same comparisons can be made by using contrast coefficients instead of Dunnett＇s test in the experiments with control groups. It was also shown that, in situations with an ordinal scale and equal spacing quantitative grouping, a trend investigation could be done by contrast coefficients. For this purpose, a small part of the data from a TUBITAK project in the Soil Science Department, Agriculture Faculty, Kahramanmaras Sutcu Imam University, was used with permission. The soils were absorbed to natural zeolite in concentration of 0, 2.5, 5 and 10 mg/kg, and after two years, the available Zinc （Zn） amounts in the soil were analyzed. As a result, in both Dunnett＇s test and contrast methods, the Zn amounts in control and 2.5 mg/kg concentration groups were found similar （P 〉 0.01）; but were different （P 〈 0.01） between control and 5 mg/kg concentration groups, and control and 10 mg/kg concentration groups. Furthermore, when orthogonal polynomial contrast coefficients were investigated, linear effects were found significant （P 〈 0.01） and cubic effects were obtained significant （P 〈 0.05）, but quadratic effect was obtained insignificant （P 〉 0.05）.
文摘Go Down, Moses is one of William Faulkner's famous novels. It consists of seven stories, most of which have been published earlier as magazine stories. When it first gets published, many reviewers regard it as a collection of stories, due to its seven loosely jointed stories with their seemingly irrelevant plots and themes. Nowadays, critics take a as a completed novel with different contrastive characters which make the stories more attractive and deepen the plots and themes.
文摘As climate change intensifies,prolonged extreme droughts are becoming a dominant force shaping terrestrial ecosystems(Smith et al.,2024).While it is well established that drought reduces grassland productivity,questions remain about whether these impacts accumulate or stabilize over time,and whether responses vary across global biomes.A groundbreaking study by Yu et al.(2025)addresses these gaps by implementing a rare,standardized multi-year drought experiment across two continents,uncovering profound differences in the ecological trajectories of Eurasian and North American grasslands.
基金support from the Research Council of Norway,Equinor,and Sekal with NFR project(Grant No.308826).
文摘Drill string vibration during drilling plays a vital and potentially decisive role in maintaining wellbore stability,as repeated impacts may lead to fatigue and borehole collapse.While drilling through geological layers,a material contrast may act as a localization point for wellbore damage.The hypothesis tested in this paper is that wellbore instability is focused on the boundary between the layers and that mechanical contrasts accelerate the wellbore collapse.In this study,an elastic-plastic damage model was employed to investigate the effects of repeated mechanical impacts on wellbore stability.A 2-dimensional(2D)model of a wellbore surrounded by contrasting materials was developed,and the accumulated damage caused by repeated lateral impacts was monitored.It was found that damage develops not only around the wall of the wellbore but also along the material boundaries.A sensitivity analysis was carried out to identify the impact of contrasts in both elastic(Young's modulus and Poisson's ratio)and plastic(cohesion,friction angle,and dilation angle)parameters between layers.Four damage patterns were identifiedin the simulated models.The results also suggested that the number of impacts required to reach the critical damage was highly affected by the contrast in elastic parameters,while cohesion and friction angle contrasts had a lesser effect.Additionally,increasing the contrast in the dilation angle localized the damage,thus reducing the number of impacts required to trigger wellbore failure.
文摘In high-intensity electromagnetic warfare,radar systems are persistently subjected to multi-jammer attacks,including potentially novel unknown jamming types that may emerge exclusively under wartime conditions.These jamming signals severely degrade radar detection performance.Precise recognition of these unknown and compound jamming signals is critical to enhancing the anti-jamming capabilities and overall reliability of radar systems.To address this challenge,this article proposes a novel open-set compound jamming cognition(OSCJC)method.The proposed method employs a detection-classification dual-network architecture,which not only overcomes the false alarm and misdetection issues of traditional closed-set recognition methods when dealing with unknown jamming but also effectively addresses the performance bottleneck of existing open-set recognition techniques focusing on single jamming scenarios in compound jamming environments.To achieve unknown jamming detection,we first employ a consistency labeling strategy to train the detection network using diverse known jamming samples.This strategy enables the network to acquire highly generalizable jamming features,thereby accurately localizing candidate regions for individual jamming components within compound jamming.Subsequently,we introduce contrastive learning to optimize the classification network,significantly enhancing both intra-class clustering and inter-class separability in the jamming feature space.This method not only improves the recognition accuracy of the classification network for known jamming types but also enhances its sensitivity to unknown jamming types.Simulations and experimental data are used to verify the effectiveness of the proposed OSCJC method.Compared with the state-of-the-art open-set recognition methods,the proposed method demonstrates superior recognition accuracy and enhanced environmental adaptability.
基金supported by the National Natural Science Foundation of China Funded Project(Project Name:Research on Robust Adaptive Allocation Mechanism of Human Machine Co-Driving System Based on NMS Features,Project Approval Number:52172381).
文摘To address the issue of scarce labeled samples and operational condition variations that degrade the accuracy of fault diagnosis models in variable-condition gearbox fault diagnosis,this paper proposes a semi-supervised masked contrastive learning and domain adaptation(SSMCL-DA)method for gearbox fault diagnosis under variable conditions.Initially,during the unsupervised pre-training phase,a dual signal augmentation strategy is devised,which simultaneously applies random masking in the time domain and random scaling in the frequency domain to unlabeled samples,thereby constructing more challenging positive sample pairs to guide the encoder in learning intrinsic features robust to condition variations.Subsequently,a ConvNeXt-Transformer hybrid architecture is employed,integrating the superior local detail modeling capacity of ConvNeXt with the robust global perception capability of Transformer to enhance feature extraction in complex scenarios.Thereafter,a contrastive learning model is constructed with the optimization objective of maximizing feature similarity across different masked instances of the same sample,enabling the extraction of consistent features from multiple masked perspectives and reducing reliance on labeled data.In the final supervised fine-tuning phase,a multi-scale attention mechanism is incorporated for feature rectification,and a domain adaptation module combining Local Maximum Mean Discrepancy(LMMD)with adversarial learning is proposed.This module embodies a dual mechanism:LMMD facilitates fine-grained class-conditional alignment,compelling features of identical fault classes to converge across varying conditions,while the domain discriminator utilizes adversarial training to guide the feature extractor toward learning domain-invariant features.Working in concert,they markedly diminish feature distribution discrepancies induced by changes in load,rotational speed,and other factors,thereby boosting the model’s adaptability to cross-condition scenarios.Experimental evaluations on the WT planetary gearbox dataset and the Case Western Reserve University(CWRU)bearing dataset demonstrate that the SSMCL-DA model effectively identifies multiple fault classes in gearboxes,with diagnostic performance substantially surpassing that of conventional methods.Under cross-condition scenarios,the model attains fault diagnosis accuracies of 99.21%for the WT planetary gearbox and 99.86%for the bearings,respectively.Furthermore,the model exhibits stable generalization capability in cross-device settings.
基金supported by the Regional Innovation System&Education(RISE)program through the Gangwon RISE Center,funded by the Ministry of Education(MOE)and the Gangwon State(G.S.),Republic of Korea(2025-RISE-10-006).
文摘This study aims to develop a novel,cost-effective method for fabricating silicone vascular phantoms(SVPs)using"chewy candy"as a dissolvable core material.The study explores the feasibility of using chewy candy to create detailed and intricate vascular models for clinical applications.The chewy candy,an amorphous material,was manually extruded to form vascular models of varying diameters.These models were embedded in a silicone mixture,which was then cured.The chewy candy was subsequently dissolved,leaving behind hollow silicone vascular channels.The SVPs were evaluated for their morphological accuracy and functionality through laser speckle contrast imaging.The SVPs successfully replicated vascular channels with consistent diameters,demonstrating minimal variation across different regions.Functional evaluation using laser speckle contrast imaging revealed distinct flow dynamics in Y-shaped and H-shaped SVPs,highlighting the potential for these phantoms to simulate realistic fluid dynamics in vascular systems.This study presents a simple,time-saving,and innovative approach to fabricating complex 3D SVPs using chewy candy.This method offers a viable alternative to traditional fabrication techniques,with potential applications in various biomedical fields.
