Bitcoin is widely used as the most classic electronic currency for various electronic services such as exchanges,gambling,marketplaces,and also scams such as high-yield investment projects.Identifying the services ope...Bitcoin is widely used as the most classic electronic currency for various electronic services such as exchanges,gambling,marketplaces,and also scams such as high-yield investment projects.Identifying the services operated by a Bitcoin address can help determine the risk level of that address and build an alert model accordingly.Feature engineering can also be used to flesh out labeled addresses and to analyze the current state of Bitcoin in a small way.In this paper,we address the problem of identifying multiple classes of Bitcoin services,and for the poor classification of individual addresses that do not have significant features,we propose a Bitcoin address identification scheme based on joint multi-model prediction using the mapping relationship between addresses and entities.The innovation of the method is to(1)Extract as many valuable features as possible when an address is given to facilitate the multi-class service identification task.(2)Unlike the general supervised model approach,this paper proposes a joint prediction scheme for multiple learners based on address-entity mapping relationships.Specifically,after obtaining the overall features,the address classification and entity clustering tasks are performed separately,and the results are subjected to graph-basedmaximization consensus.The final result ismade to baseline the individual address classification results while satisfying the constraint of having similarly behaving entities as far as possible.By testing and evaluating over 26,000 Bitcoin addresses,our feature extraction method captures more useful features.In addition,the combined multi-learner model obtained results that exceeded the baseline classifier reaching an accuracy of 77.4%.展开更多
Introduction: A practical staging classification that has prognostic significance in mucinous appendiceal neoplasms represents an unmet need in oncology. The purpose of this study is to present a second edition of the...Introduction: A practical staging classification that has prognostic significance in mucinous appendiceal neoplasms represents an unmet need in oncology. The purpose of this study is to present a second edition of the PSDSS in mucinous appendiceal neoplasms with or without peritoneal dissemination based on the AJCC/TNM 8<sup>th</sup> edition. Materials and Methods: We analyzed 229 patients based on the AJCC/TNM 8<sup>th</sup> edition incorporating G (grade) and E (extent of disease). The impact of these 5 clinicopathological variables (T, N, M, G, E) is scored as stages 0 to IV and is reported as the Esquivel Peritoneal Surface Disease Severity Score (E-PSDSS). Results: One hundred and seventy-three patients underwent cytoreductive surgery (CRS) and HIPEC. There were 30 (13.1%), 56 (24.4%), 48 (20.9%), 20 (8.7%) and 75 (32.7%) patients with E-PSDSS 0, I, II, III, and IV, respectively. Five-year overall survival was 100%, 100%, 84.46%, 52.29% and 12.92% for E-PSDSS 0, I, II, III and IV, respectively (p Conclusion: The E-PSDSS combines specimen examination and reporting according to the College of American Pathologists with the pTNM requirements from the AJCC staging manual. It represents an important prognostic indicator in patients with mucinous appendiceal neoplasms.展开更多
Microglia,which are the resident macrophages of the central nervous system,are an important part of the inflammatory response that occurs after cerebral ischemia.Vav guanine nucleotide exchange factor 1(Vav1) is a gua...Microglia,which are the resident macrophages of the central nervous system,are an important part of the inflammatory response that occurs after cerebral ischemia.Vav guanine nucleotide exchange factor 1(Vav1) is a guanine nucleotide exchange factor that is related to microglial activation.However,how Vav1 participates in the inflammato ry response after cerebral ischemia/reperfusion inj ury remains unclea r.In this study,we subjected rats to occlusion and repe rfusion of the middle cerebral artery and subjected the BV-2 mic roglia cell line to oxygen-glucose deprivatio n/reoxygenation to mimic cerebral ischemia/repe rfusion in vivo and in vitro,respectively.We found that Vav1 levels were increased in the brain tissue of rats subjected to occlusion and reperfusion of the middle cerebral arte ry and in BV-2 cells subjected to oxygen-glucose deprivation/reoxygenation.Silencing Vav1 reduced the cerebral infarct volume and brain water content,inhibited neuronal loss and apoptosis in the ischemic penumbra,and im p roved neurological function in rats subjected to occlusion and repe rfusion of the middle cerebral artery.Further analysis showed that Vav1 was almost exclusively localized to microglia and that Vav1 downregulation inhibited microglial activation and the NOD-like receptor pyrin 3(NLRP3) inflammasome in the ischemic penumbra,as well as the expression of inflammato ry facto rs.In addition,Vov1 knoc kdown decreased the inflammatory response exhibited by BV-2 cells after oxygen-glucose deprivation/reoxyge nation.Taken together,these findings show that silencing Vav1 attenuates inflammation and neuronal apoptosis in rats subjected to cerebral ischemia/repe rfusion through inhibiting the activation of mic roglia and NLRP3 inflammasome.展开更多
[Objectives]This study was conducted to investigate the effects of Polygonatum odoratum polysaccharides on the quality of white chili peppers in jars.[Methods]White chili peppers were pickled by adding different conce...[Objectives]This study was conducted to investigate the effects of Polygonatum odoratum polysaccharides on the quality of white chili peppers in jars.[Methods]White chili peppers were pickled by adding different concentrations of P.odoratum polysaccharides with traditional pickling technology,and its nitrite content,pH and sensory quality were analyzed and detected.[Results]The results showed that,compared with the control group without adding P.odoratum polysaccharides,the nitrite content in white chili peppers in jars decreased after adding P.odoratum polysaccharides.When the addition amount of P.odoratum polysaccharides was 0.002%,the inhibition rate of nitrite reached the maximum.Under the same fermentation time,P.odoratum polysaccharides could significantly reduce the pH value of pickles.When the addition amount of P.odoratum polysaccharide was 0.002%and the pickling time was 3 months,the sensory quality of white chili peppers in jars was the best.At this point,white chili peppers in jars had rich aroma and tasted soft and sour,and the sour and salinity were suitable.As the fermentation time continued to increase,the chili aroma of white chili peppers in jars gradually decreased,and the sour taste became more pronounced.[Conclusions]This study can provide reference for the safety and quality control of white chili peppers in jars.展开更多
The test selection and optimization(TSO) can improve the abilities of fault diagnosis, prognosis and health-state evaluation for prognostics and health management(PHM) systems. Traditionally, TSO mainly focuses on fau...The test selection and optimization(TSO) can improve the abilities of fault diagnosis, prognosis and health-state evaluation for prognostics and health management(PHM) systems. Traditionally, TSO mainly focuses on fault detection and isolation, but they cannot provide an effective guide for the design for testability(DFT) to improve the PHM performance level. To solve the problem, a model of TSO for PHM systems is proposed. Firstly,through integrating the characteristics of fault severity and propagation time, and analyzing the test timing and sensitivity, a testability model based on failure evolution mechanism model(FEMM) for PHM systems is built up. This model describes the fault evolutiontest dependency using the fault-symptom parameter matrix and symptom parameter-test matrix. Secondly, a novel method of inherent testability analysis for PHM systems is developed based on the above information. Having completed the analysis, a TSO model, whose objective is to maximize fault trackability and minimize the test cost, is proposed through inherent testability analysis results, and an adaptive simulated annealing genetic algorithm(ASAGA) is introduced to solve the TSO problem. Finally, a case of a centrifugal pump system is used to verify the feasibility and effectiveness of the proposed models and methods. The results show that the proposed technology is important for PHM systems to select and optimize the test set in order to improve their performance level.展开更多
Vegetation in wetlands is a large-scale nature-based resource that can provide multiple benefits to human beings and the environment,such as wave attenuation in coastal zones.Traditionally,there are two main calibrati...Vegetation in wetlands is a large-scale nature-based resource that can provide multiple benefits to human beings and the environment,such as wave attenuation in coastal zones.Traditionally,there are two main calibration approaches to calculate the attenuation of wave driven by vegetation.The first method is a straightforward one based on the exponential attenuation of wave height in the direction of wave transmission,which,however,overlooks the crucial drag coefficient(CD).The other method is in accordance with more complicate equations for predicting the damping factor,which is regarded as a function of CD.In this study,a new relation,combining these above two conventional approaches,is proposed to predict the CD in an operative approach.Results show that values yielded by the new assessment method perform a strong linear relationship with a collection of historical observations,with a promising R2 value of 0.90.Besides,the linear regression derives a new predictive equation for the bulk drag coefficient.Additionally,a calibrated value of 4 for the empirical plant drag coefficient(CP)is revealed.Overall,this new equation,with the superiority of the convenient exponential regression,is expected to be a rapid assessment method for calculating wave attenuation by vegetation and predicting the drag coefficient.展开更多
Recommender systems are very useful for people to explore what they really need.Academic papers are important achievements for researchers and they often have a great deal of choice to submit their papers.In order to ...Recommender systems are very useful for people to explore what they really need.Academic papers are important achievements for researchers and they often have a great deal of choice to submit their papers.In order to improve the efficiency of selecting the most suitable journals for publishing their works,journal recommender systems(JRS)can automatically provide a small number of candidate journals based on key information such as the title and the abstract.However,users or journal owners may attack the system for their own purposes.In this paper,we discuss about the adversarial attacks against content-based filtering JRS.We propose both targeted attack method that makes some target journals appear more often in the system and non-targeted attack method that makes the system provide incorrect recommendations.We also conduct extensive experiments to validate the proposed methods.We hope this paper could help improve JRS by realizing the existence of such adversarial attacks.展开更多
To deal with the expected diversification on traffic types, the fundamental waveform of the upcoming5 G standard must be sufficiently flexible. In the 4th generation wireless networks(e.g., cellular LTE and Wi- Fi802....To deal with the expected diversification on traffic types, the fundamental waveform of the upcoming5 G standard must be sufficiently flexible. In the 4th generation wireless networks(e.g., cellular LTE and Wi- Fi802.11ac), orthogonal frequency division multiplexing(OFDM) has been widely adopted to combat frequency selectivity and thus improve the spectrum efficiency. Holding various advantages such as backward compatibility with LTE, ease of hardware implementation, time-localized low-latency transmission and straightforward combination with multi-antenna transmission, OFDM will remain as an important waveform candidate for 5G. However,OFDM alone appears to be insufficient in terms of the requirements faced by 5G waveform, such as high flexibility to accommodate different waveform numerologies for an efficient support of diversified traffic types and channel characteristics. In this work, we present a new waveform format, named as filtered-OFDM(f-OFDM) and illustrate its potential and benefits for serving as the underlying waveform of 5G.展开更多
With the evolution of location-based services(LBS),a new type of LBS has already gain a lot of attention and implementation,we name this kind of LBS as the Device-Dependent LBS(DLBS).In DLBS,the service provider(SP)wi...With the evolution of location-based services(LBS),a new type of LBS has already gain a lot of attention and implementation,we name this kind of LBS as the Device-Dependent LBS(DLBS).In DLBS,the service provider(SP)will not only send the information according to the user’s location,more significant,he also provides a service device which will be carried by the user.DLBS has been successfully practised in some of the large cities around the world,for example,the shared bicycle in Beijing and London.In this paper,we,for the first time,blow the whistle of the new location privacy challenges caused by DLBS,since the service device is enabled to perform the localization without the permission of the user.To conquer these threats,we design a service architecture along with a credit system between DLBS provider and the user.The credit system tie together the DLBS device usability with the curious behaviour upon user’s location privacy,DLBS provider has to sacrifice their revenue in order to gain extra location information of their device.We make the simulation of our proposed scheme and the result convince its effectiveness.展开更多
With the development of Information technology and the popularization of Internet,whenever and wherever possible,people can connect to the Internet optionally.Meanwhile,the security of network traffic is threatened by...With the development of Information technology and the popularization of Internet,whenever and wherever possible,people can connect to the Internet optionally.Meanwhile,the security of network traffic is threatened by various of online malicious behaviors.The aim of an intrusion detection system(IDS)is to detect the network behaviors which are diverse and malicious.Since a conventional firewall cannot detect most of the malicious behaviors,such as malicious network traffic or computer abuse,some advanced learning methods are introduced and integrated with intrusion detection approaches in order to improve the performance of detection approaches.However,there are very few related studies focusing on both the effective detection for attacks and the representation for malicious behaviors with graph.In this paper,a novel intrusion detection approach IDBFG(Intrusion Detection Based on Feature Graph)is proposed which first filters normal connections with grid partitions,and then records the patterns of various attacks with a novel graph structure,and the behaviors in accordance with the patterns in graph are detected as intrusion behaviors.The experimental results on KDD-Cup 99 dataset show that IDBFG performs better than SVM(Supprot Vector Machines)and Decision Tree which are trained and tested in original feature space in terms of detection rates,false alarm rates and run time.展开更多
BGP monitors are currently the main data resource of AS-level topology measurement,and the integrity of measurement result is limited to the location of such BGP monitors.However,there is currently no work to conduct ...BGP monitors are currently the main data resource of AS-level topology measurement,and the integrity of measurement result is limited to the location of such BGP monitors.However,there is currently no work to conduct a comprehensive study of the range of measurement results for a single BGP monitor.In this paper,we take the first step to describe the observed topology of each BGP monitor.To that end,we first investigate the construction and theoretical up-limit of the measured topology of a BGP monitor based on the valley-free model,then we evaluate the individual parts of the measured topology by comparing such theoretical results with the actually observed data.We find that:1)for more than 90%of the monitors,the actually observed peer-peer links merely takes a small part of all theoretical visible links;2)increasing the BGP monitors in the same AS may improve the measurement result,but with limited improvement;and 3)deploying multiple BGP monitors in different ASs can significantly improve the measurement results,but non-local BGP monitors can hardly replace the local AS BGP monitors.We also propose a metric for monitor selection optimization,and prove its effectiveness with experiment evaluation.展开更多
Cardiac coronary angiography is a major technique that assists physicians during interventional heart surgery.Under X-ray irradiation,the physician injects a contrast agent through a catheter and determines the corona...Cardiac coronary angiography is a major technique that assists physicians during interventional heart surgery.Under X-ray irradiation,the physician injects a contrast agent through a catheter and determines the coronary arteries’state in real time.However,to obtain a more accurate state of the coronary arteries,physicians need to increase the fre-quency and intensity of X-ray exposure,which will inevitably increase the potential for harm to both the patient and the surgeon.In the work reported here,we use advanced deep learning algorithms to fi nd a method of frame interpola-tion for coronary angiography videos that reduces the frequency of X-ray exposure by reducing the frame rate of the coronary angiography video,thereby reducing X-ray-induced damage to physicians.We established a new coronary angiography image group dataset containing 95,039 groups of images extracted from 31 videos.Each group includes three consecutive images,which are used to train the video interpolation network model.We apply six popular frame interpolation methods to this dataset to confi rm that the video frame interpolation technology can reduce the video frame rate and reduce exposure of physicians to X-rays.展开更多
Recently dependency information has been used in different ways to improve neural machine translation.For example,add dependency labels to the hidden states of source words.Or the contiguous information of a source wo...Recently dependency information has been used in different ways to improve neural machine translation.For example,add dependency labels to the hidden states of source words.Or the contiguous information of a source word would be found according to the dependency tree and then be learned independently and be added into Neural Machine Translation(NMT)model as a unit in various ways.However,these works are all limited to the use of dependency information to enrich the hidden states of source words.Since many works in Statistical Machine Translation(SMT)and NMT have proven the validity and potential of using dependency information.We believe that there are still many ways to apply dependency information in the NMT structure.In this paper,we explore a new way to use dependency information to improve NMT.Based on the theory of local attention mechanism,we present Dependency-based Local Attention Approach(DLAA),a new attention mechanism that allowed the NMT model to trace the dependency words related to the current translating words.Our work also indicates that dependency information could help to supervise attention mechanism.Experiment results on WMT 17 Chineseto-English translation task shared training datasets show that our model is effective and perform distinctively on long sentence translation.展开更多
Single-walled carbon nanotube(SWNT)thin film electrodes have been printed on flexible substrates and cloth fabrics by using SWNT inks and an off-the-shelf inkjet printer,with features of controlled pattern geometry(0....Single-walled carbon nanotube(SWNT)thin film electrodes have been printed on flexible substrates and cloth fabrics by using SWNT inks and an off-the-shelf inkjet printer,with features of controlled pattern geometry(0.4-6 cm^(2)),location,controllable thickness(20-200 nm),and tunable electrical conductivity.The as-printed SWNT films were then sandwiched together with a piece of printable polymer electrolyte to form flexible and wearable supercapacitors,which displayed good capacitive behavior even after 1,000 charge/discharge cycles.Furthermore,a simple and efficient route to produce ruthenium oxide(RuO_(2))nanowire/SWNT hybrid films has been developed,and it was found that the knee frequency of the hybrid thin film electrodes can reach 1,500 Hz,which is much higher than the knee frequency of the bare SWNT electrodes(~158 Hz).In addition,with the integration of RuO_(2) nanowires,the performance of the printed SWNT supercapacitor was significantly improved in terms of its specific capacitance of 138 F/g,power density of 96 kW/kg,and energy density of 18.8 Wh/kg.The results indicate the potential of printable energy storage devices and their significant promise for application in wearable energy storage devices.展开更多
Following the deregulation of the power industry,transmission expansion planning(TEP)has become more complicated due to the presence of uncertainties and conflicting objectives in a market environment.Also,the growing...Following the deregulation of the power industry,transmission expansion planning(TEP)has become more complicated due to the presence of uncertainties and conflicting objectives in a market environment.Also,the growing concern on global warming highlights the importance of considering carbon pricing policies during TEP.In this paper,a probabilistic TEP approach is proposed with the integration of a chance constrained load curtailment index.The formulated dynamic programming problem is solved by a hybrid solution algorithm in an iterative process.The performance of our approach is demonstrated by case studies on a modified IEEE 14-bus system.Simulation results prove that our approach can provide network planners with comprehensive information regarding effects of uncertainties on TEP schemes,allowing them to adjust planning strategies based on their risk aversion levels or financial constraints.展开更多
Mass migration of rural workers to cities will inevitably increase urban housing demand.However,the scale of vacant urban housing will increase in future as a result of the population aging and the rising number of em...Mass migration of rural workers to cities will inevitably increase urban housing demand.However,the scale of vacant urban housing will increase in future as a result of the population aging and the rising number of empty nesters.Therefore,demographic transition may not only increase housing demand,but also increase housing supply.Using an overlapping generations model,the present paper investigates the impact of demographic transition on housing consumption.We find that there is a nonlinear relationship between the elderly dependency ratio and housing consumption in China.With the deepening of population aging,housing consumption will increase;when the elderly dependency ratio reaches a turning point,housing consumption will decrease.The turning point of the nonlinear curve also depends on population mobility.A greater degree of population mobility will result in a delayed turning point.Furthermore,the turning point of the nonlinear curve will emerge when China's elderly dependency ratio reaches a value of 32 percent in 2025.This means that over the next decade,China should continue to increase the level of housing supply.展开更多
基金sponsored by the National Natural Science Foundation of China Nos.62172353,62302114 and U20B2046Future Network Scientific Research Fund Project No.FNSRFP-2021-YB-48Innovation Fund Program of the Engineering Research Center for Integration and Application of Digital Learning Technology of Ministry of Education No.1221045。
文摘Bitcoin is widely used as the most classic electronic currency for various electronic services such as exchanges,gambling,marketplaces,and also scams such as high-yield investment projects.Identifying the services operated by a Bitcoin address can help determine the risk level of that address and build an alert model accordingly.Feature engineering can also be used to flesh out labeled addresses and to analyze the current state of Bitcoin in a small way.In this paper,we address the problem of identifying multiple classes of Bitcoin services,and for the poor classification of individual addresses that do not have significant features,we propose a Bitcoin address identification scheme based on joint multi-model prediction using the mapping relationship between addresses and entities.The innovation of the method is to(1)Extract as many valuable features as possible when an address is given to facilitate the multi-class service identification task.(2)Unlike the general supervised model approach,this paper proposes a joint prediction scheme for multiple learners based on address-entity mapping relationships.Specifically,after obtaining the overall features,the address classification and entity clustering tasks are performed separately,and the results are subjected to graph-basedmaximization consensus.The final result ismade to baseline the individual address classification results while satisfying the constraint of having similarly behaving entities as far as possible.By testing and evaluating over 26,000 Bitcoin addresses,our feature extraction method captures more useful features.In addition,the combined multi-learner model obtained results that exceeded the baseline classifier reaching an accuracy of 77.4%.
文摘Introduction: A practical staging classification that has prognostic significance in mucinous appendiceal neoplasms represents an unmet need in oncology. The purpose of this study is to present a second edition of the PSDSS in mucinous appendiceal neoplasms with or without peritoneal dissemination based on the AJCC/TNM 8<sup>th</sup> edition. Materials and Methods: We analyzed 229 patients based on the AJCC/TNM 8<sup>th</sup> edition incorporating G (grade) and E (extent of disease). The impact of these 5 clinicopathological variables (T, N, M, G, E) is scored as stages 0 to IV and is reported as the Esquivel Peritoneal Surface Disease Severity Score (E-PSDSS). Results: One hundred and seventy-three patients underwent cytoreductive surgery (CRS) and HIPEC. There were 30 (13.1%), 56 (24.4%), 48 (20.9%), 20 (8.7%) and 75 (32.7%) patients with E-PSDSS 0, I, II, III, and IV, respectively. Five-year overall survival was 100%, 100%, 84.46%, 52.29% and 12.92% for E-PSDSS 0, I, II, III and IV, respectively (p Conclusion: The E-PSDSS combines specimen examination and reporting according to the College of American Pathologists with the pTNM requirements from the AJCC staging manual. It represents an important prognostic indicator in patients with mucinous appendiceal neoplasms.
基金Natural Science Foundation of Liaoning Province (General Program),No.2017010825 (to JQ)。
文摘Microglia,which are the resident macrophages of the central nervous system,are an important part of the inflammatory response that occurs after cerebral ischemia.Vav guanine nucleotide exchange factor 1(Vav1) is a guanine nucleotide exchange factor that is related to microglial activation.However,how Vav1 participates in the inflammato ry response after cerebral ischemia/reperfusion inj ury remains unclea r.In this study,we subjected rats to occlusion and repe rfusion of the middle cerebral artery and subjected the BV-2 mic roglia cell line to oxygen-glucose deprivatio n/reoxygenation to mimic cerebral ischemia/repe rfusion in vivo and in vitro,respectively.We found that Vav1 levels were increased in the brain tissue of rats subjected to occlusion and reperfusion of the middle cerebral arte ry and in BV-2 cells subjected to oxygen-glucose deprivation/reoxygenation.Silencing Vav1 reduced the cerebral infarct volume and brain water content,inhibited neuronal loss and apoptosis in the ischemic penumbra,and im p roved neurological function in rats subjected to occlusion and repe rfusion of the middle cerebral artery.Further analysis showed that Vav1 was almost exclusively localized to microglia and that Vav1 downregulation inhibited microglial activation and the NOD-like receptor pyrin 3(NLRP3) inflammasome in the ischemic penumbra,as well as the expression of inflammato ry facto rs.In addition,Vov1 knoc kdown decreased the inflammatory response exhibited by BV-2 cells after oxygen-glucose deprivation/reoxyge nation.Taken together,these findings show that silencing Vav1 attenuates inflammation and neuronal apoptosis in rats subjected to cerebral ischemia/repe rfusion through inhibiting the activation of mic roglia and NLRP3 inflammasome.
基金Supported by General Project of Natural Science Foundation of Hunan Province (2022JJ30312)Enterprise Science and Technology Innovation Team Construction Project of Loudi Science and Technology Innovation Program in 2022.
文摘[Objectives]This study was conducted to investigate the effects of Polygonatum odoratum polysaccharides on the quality of white chili peppers in jars.[Methods]White chili peppers were pickled by adding different concentrations of P.odoratum polysaccharides with traditional pickling technology,and its nitrite content,pH and sensory quality were analyzed and detected.[Results]The results showed that,compared with the control group without adding P.odoratum polysaccharides,the nitrite content in white chili peppers in jars decreased after adding P.odoratum polysaccharides.When the addition amount of P.odoratum polysaccharides was 0.002%,the inhibition rate of nitrite reached the maximum.Under the same fermentation time,P.odoratum polysaccharides could significantly reduce the pH value of pickles.When the addition amount of P.odoratum polysaccharide was 0.002%and the pickling time was 3 months,the sensory quality of white chili peppers in jars was the best.At this point,white chili peppers in jars had rich aroma and tasted soft and sour,and the sour and salinity were suitable.As the fermentation time continued to increase,the chili aroma of white chili peppers in jars gradually decreased,and the sour taste became more pronounced.[Conclusions]This study can provide reference for the safety and quality control of white chili peppers in jars.
基金supported by the National Natural Science Foundation of China(51175502)
文摘The test selection and optimization(TSO) can improve the abilities of fault diagnosis, prognosis and health-state evaluation for prognostics and health management(PHM) systems. Traditionally, TSO mainly focuses on fault detection and isolation, but they cannot provide an effective guide for the design for testability(DFT) to improve the PHM performance level. To solve the problem, a model of TSO for PHM systems is proposed. Firstly,through integrating the characteristics of fault severity and propagation time, and analyzing the test timing and sensitivity, a testability model based on failure evolution mechanism model(FEMM) for PHM systems is built up. This model describes the fault evolutiontest dependency using the fault-symptom parameter matrix and symptom parameter-test matrix. Secondly, a novel method of inherent testability analysis for PHM systems is developed based on the above information. Having completed the analysis, a TSO model, whose objective is to maximize fault trackability and minimize the test cost, is proposed through inherent testability analysis results, and an adaptive simulated annealing genetic algorithm(ASAGA) is introduced to solve the TSO problem. Finally, a case of a centrifugal pump system is used to verify the feasibility and effectiveness of the proposed models and methods. The results show that the proposed technology is important for PHM systems to select and optimize the test set in order to improve their performance level.
基金The National Key Research and Development Program of China under contract No.2016YFC0402607the Key Research and Development Projects in Guangdong Province under contract No.2019B111101002+1 种基金the 2018 Guangzhou Science and Technology Project under contract No.201806010143the Water Resource Science and Technology Innovation Program of Guangdong Province under contract No.2017-17。
文摘Vegetation in wetlands is a large-scale nature-based resource that can provide multiple benefits to human beings and the environment,such as wave attenuation in coastal zones.Traditionally,there are two main calibration approaches to calculate the attenuation of wave driven by vegetation.The first method is a straightforward one based on the exponential attenuation of wave height in the direction of wave transmission,which,however,overlooks the crucial drag coefficient(CD).The other method is in accordance with more complicate equations for predicting the damping factor,which is regarded as a function of CD.In this study,a new relation,combining these above two conventional approaches,is proposed to predict the CD in an operative approach.Results show that values yielded by the new assessment method perform a strong linear relationship with a collection of historical observations,with a promising R2 value of 0.90.Besides,the linear regression derives a new predictive equation for the bulk drag coefficient.Additionally,a calibrated value of 4 for the empirical plant drag coefficient(CP)is revealed.Overall,this new equation,with the superiority of the convenient exponential regression,is expected to be a rapid assessment method for calculating wave attenuation by vegetation and predicting the drag coefficient.
基金This work is supported by the National Natural Science Foundation of China under Grant Nos.U1636215,61902082the Guangdong Key R&D Program of China 2019B010136003Guangdong Province Universities and Colleges Pearl River Scholar Funded Scheme(2019).
文摘Recommender systems are very useful for people to explore what they really need.Academic papers are important achievements for researchers and they often have a great deal of choice to submit their papers.In order to improve the efficiency of selecting the most suitable journals for publishing their works,journal recommender systems(JRS)can automatically provide a small number of candidate journals based on key information such as the title and the abstract.However,users or journal owners may attack the system for their own purposes.In this paper,we discuss about the adversarial attacks against content-based filtering JRS.We propose both targeted attack method that makes some target journals appear more often in the system and non-targeted attack method that makes the system provide incorrect recommendations.We also conduct extensive experiments to validate the proposed methods.We hope this paper could help improve JRS by realizing the existence of such adversarial attacks.
文摘To deal with the expected diversification on traffic types, the fundamental waveform of the upcoming5 G standard must be sufficiently flexible. In the 4th generation wireless networks(e.g., cellular LTE and Wi- Fi802.11ac), orthogonal frequency division multiplexing(OFDM) has been widely adopted to combat frequency selectivity and thus improve the spectrum efficiency. Holding various advantages such as backward compatibility with LTE, ease of hardware implementation, time-localized low-latency transmission and straightforward combination with multi-antenna transmission, OFDM will remain as an important waveform candidate for 5G. However,OFDM alone appears to be insufficient in terms of the requirements faced by 5G waveform, such as high flexibility to accommodate different waveform numerologies for an efficient support of diversified traffic types and channel characteristics. In this work, we present a new waveform format, named as filtered-OFDM(f-OFDM) and illustrate its potential and benefits for serving as the underlying waveform of 5G.
基金This work was supported by National Natural Science Foundation of China(Grant Nos.61871140,61702223,61702220,61572153,61723022,61601146)and the National Key research and Development Plan(Grant No.2018YFB0803504,2017YFB0803300).
文摘With the evolution of location-based services(LBS),a new type of LBS has already gain a lot of attention and implementation,we name this kind of LBS as the Device-Dependent LBS(DLBS).In DLBS,the service provider(SP)will not only send the information according to the user’s location,more significant,he also provides a service device which will be carried by the user.DLBS has been successfully practised in some of the large cities around the world,for example,the shared bicycle in Beijing and London.In this paper,we,for the first time,blow the whistle of the new location privacy challenges caused by DLBS,since the service device is enabled to perform the localization without the permission of the user.To conquer these threats,we design a service architecture along with a credit system between DLBS provider and the user.The credit system tie together the DLBS device usability with the curious behaviour upon user’s location privacy,DLBS provider has to sacrifice their revenue in order to gain extra location information of their device.We make the simulation of our proposed scheme and the result convince its effectiveness.
基金This research was funded in part by the National Natural Science Foundation of China(61871140,61872100,61572153,U1636215,61572492,61672020)the National Key research and Development Plan(Grant No.2018YFB0803504)Open Fund of Beijing Key Laboratory of IOT Information Security Technology(J6V0011104).
文摘With the development of Information technology and the popularization of Internet,whenever and wherever possible,people can connect to the Internet optionally.Meanwhile,the security of network traffic is threatened by various of online malicious behaviors.The aim of an intrusion detection system(IDS)is to detect the network behaviors which are diverse and malicious.Since a conventional firewall cannot detect most of the malicious behaviors,such as malicious network traffic or computer abuse,some advanced learning methods are introduced and integrated with intrusion detection approaches in order to improve the performance of detection approaches.However,there are very few related studies focusing on both the effective detection for attacks and the representation for malicious behaviors with graph.In this paper,a novel intrusion detection approach IDBFG(Intrusion Detection Based on Feature Graph)is proposed which first filters normal connections with grid partitions,and then records the patterns of various attacks with a novel graph structure,and the behaviors in accordance with the patterns in graph are detected as intrusion behaviors.The experimental results on KDD-Cup 99 dataset show that IDBFG performs better than SVM(Supprot Vector Machines)and Decision Tree which are trained and tested in original feature space in terms of detection rates,false alarm rates and run time.
基金This work was supported in part by the Guangdong Province Key Research and Development Plan(Grant No.2019B010137004)the National Key research and Development Plan(Grant No.2018YFB0803504).
文摘BGP monitors are currently the main data resource of AS-level topology measurement,and the integrity of measurement result is limited to the location of such BGP monitors.However,there is currently no work to conduct a comprehensive study of the range of measurement results for a single BGP monitor.In this paper,we take the first step to describe the observed topology of each BGP monitor.To that end,we first investigate the construction and theoretical up-limit of the measured topology of a BGP monitor based on the valley-free model,then we evaluate the individual parts of the measured topology by comparing such theoretical results with the actually observed data.We find that:1)for more than 90%of the monitors,the actually observed peer-peer links merely takes a small part of all theoretical visible links;2)increasing the BGP monitors in the same AS may improve the measurement result,but with limited improvement;and 3)deploying multiple BGP monitors in different ASs can significantly improve the measurement results,but non-local BGP monitors can hardly replace the local AS BGP monitors.We also propose a metric for monitor selection optimization,and prove its effectiveness with experiment evaluation.
文摘Cardiac coronary angiography is a major technique that assists physicians during interventional heart surgery.Under X-ray irradiation,the physician injects a contrast agent through a catheter and determines the coronary arteries’state in real time.However,to obtain a more accurate state of the coronary arteries,physicians need to increase the fre-quency and intensity of X-ray exposure,which will inevitably increase the potential for harm to both the patient and the surgeon.In the work reported here,we use advanced deep learning algorithms to fi nd a method of frame interpola-tion for coronary angiography videos that reduces the frequency of X-ray exposure by reducing the frame rate of the coronary angiography video,thereby reducing X-ray-induced damage to physicians.We established a new coronary angiography image group dataset containing 95,039 groups of images extracted from 31 videos.Each group includes three consecutive images,which are used to train the video interpolation network model.We apply six popular frame interpolation methods to this dataset to confi rm that the video frame interpolation technology can reduce the video frame rate and reduce exposure of physicians to X-rays.
基金This research was funded in part by the National Natural Science Foundation of China(61871140,61872100,61572153,U1636215,61572492,61672020)the National Key research and Development Plan(Grant No.2018YFB0803504)Open Fund of Beijing Key Laboratory of IOT Information Security Technology(J6V0011104).
文摘Recently dependency information has been used in different ways to improve neural machine translation.For example,add dependency labels to the hidden states of source words.Or the contiguous information of a source word would be found according to the dependency tree and then be learned independently and be added into Neural Machine Translation(NMT)model as a unit in various ways.However,these works are all limited to the use of dependency information to enrich the hidden states of source words.Since many works in Statistical Machine Translation(SMT)and NMT have proven the validity and potential of using dependency information.We believe that there are still many ways to apply dependency information in the NMT structure.In this paper,we explore a new way to use dependency information to improve NMT.Based on the theory of local attention mechanism,we present Dependency-based Local Attention Approach(DLAA),a new attention mechanism that allowed the NMT model to trace the dependency words related to the current translating words.Our work also indicates that dependency information could help to supervise attention mechanism.Experiment results on WMT 17 Chineseto-English translation task shared training datasets show that our model is effective and perform distinctively on long sentence translation.
基金We acknowledge financial support from the National Science Foundation(Nos.CCF 0726815 and CCF 0702204).
文摘Single-walled carbon nanotube(SWNT)thin film electrodes have been printed on flexible substrates and cloth fabrics by using SWNT inks and an off-the-shelf inkjet printer,with features of controlled pattern geometry(0.4-6 cm^(2)),location,controllable thickness(20-200 nm),and tunable electrical conductivity.The as-printed SWNT films were then sandwiched together with a piece of printable polymer electrolyte to form flexible and wearable supercapacitors,which displayed good capacitive behavior even after 1,000 charge/discharge cycles.Furthermore,a simple and efficient route to produce ruthenium oxide(RuO_(2))nanowire/SWNT hybrid films has been developed,and it was found that the knee frequency of the hybrid thin film electrodes can reach 1,500 Hz,which is much higher than the knee frequency of the bare SWNT electrodes(~158 Hz).In addition,with the integration of RuO_(2) nanowires,the performance of the printed SWNT supercapacitor was significantly improved in terms of its specific capacitance of 138 F/g,power density of 96 kW/kg,and energy density of 18.8 Wh/kg.The results indicate the potential of printable energy storage devices and their significant promise for application in wearable energy storage devices.
文摘Following the deregulation of the power industry,transmission expansion planning(TEP)has become more complicated due to the presence of uncertainties and conflicting objectives in a market environment.Also,the growing concern on global warming highlights the importance of considering carbon pricing policies during TEP.In this paper,a probabilistic TEP approach is proposed with the integration of a chance constrained load curtailment index.The formulated dynamic programming problem is solved by a hybrid solution algorithm in an iterative process.The performance of our approach is demonstrated by case studies on a modified IEEE 14-bus system.Simulation results prove that our approach can provide network planners with comprehensive information regarding effects of uncertainties on TEP schemes,allowing them to adjust planning strategies based on their risk aversion levels or financial constraints.
基金financially supported by theNational Social Science Foundation of China(No.11CJL011)
文摘Mass migration of rural workers to cities will inevitably increase urban housing demand.However,the scale of vacant urban housing will increase in future as a result of the population aging and the rising number of empty nesters.Therefore,demographic transition may not only increase housing demand,but also increase housing supply.Using an overlapping generations model,the present paper investigates the impact of demographic transition on housing consumption.We find that there is a nonlinear relationship between the elderly dependency ratio and housing consumption in China.With the deepening of population aging,housing consumption will increase;when the elderly dependency ratio reaches a turning point,housing consumption will decrease.The turning point of the nonlinear curve also depends on population mobility.A greater degree of population mobility will result in a delayed turning point.Furthermore,the turning point of the nonlinear curve will emerge when China's elderly dependency ratio reaches a value of 32 percent in 2025.This means that over the next decade,China should continue to increase the level of housing supply.
