In the field of intelligent education,the integration of artificial intelligence,especially deep learning technologies,has garnered significant attention.Knowledge tracing(KT)plays a pivotal role in this field by pred...In the field of intelligent education,the integration of artificial intelligence,especially deep learning technologies,has garnered significant attention.Knowledge tracing(KT)plays a pivotal role in this field by predicting students’future performance through the analysis of historical interaction data,thereby assisting educators in evaluating knowledgemastery and tailoring instructional strategies.Traditional knowledge tracingmethods,largely based on Recurrent Neural Networks(RNNs)and Transformer models,primarily focus on capturing long-term interaction patterns in sequential data.However,these models may neglect crucial short-term dynamics and other relevant features.This paper introduces a novel approach to knowledge tracing by leveraging a pure Multilayer Perceptron(MLP)architecture.We proposeMixerKT,a knowledge tracing model based on theHyperMixer framework,which uniquely integrates global and localMixer feature extractors.This architecture enables more effective extraction of both long-terminteraction trends and recent learning behaviors,addressing limitations in currentmodels thatmay overlook these key aspects.Empirical evaluations on twowidely-used datasets,ASSIS Tments2009 and Algebra2005,demonstrate that MixerKT consistently outperforms several state-of-the-art models,including DKT,SAKT,and Separated Self-Attentive Neural Knowledge Tracing(SAINT).Specifically,MixerKT achieves higher prediction accuracy,highlighting its effectiveness in capturing the nuances of learners’knowledge states.These results indicate that our model provides a more comprehensive representation of student learning patterns,enhancing the ability to predict future performance with greater precision.展开更多
BACKGROUND Gastric cancer(GC)is a highly prevalent gastrointestinal tract tumor.Several trials have demonstrated that the location of GC can affect patient prognosis.However,the factors determining tumor location rema...BACKGROUND Gastric cancer(GC)is a highly prevalent gastrointestinal tract tumor.Several trials have demonstrated that the location of GC can affect patient prognosis.However,the factors determining tumor location remain unclear.AIM To investigate the tumor location of patients,we went on to study the influencing factors that lead to changes in the location of GC.METHODS A retrospective evaluation was carried out on 3287 patients who underwent gastrectomy for GC in Zhejiang Cancer Hospital.The patients were followed up post-diagnosis and post-gastrectomy.The clinicopathological variables and overall survival of the patients were recorded.By analyzing the location of GC,the tumor location was divided into four categories:“Upper”,“middle”,“lower”,and“total”.Statistical software was utilized to analyze the relationship of each variable with the location of GC.RESULTS A total of 3287 patients were included in this study.The clinicopathological indices of gender,age,serum levels of carcinoembryonic antigen(CEA),carbohydrate antigen(CA19-9)and CA72-4 levels,were significantly associated with tumor location in patients with GC.In addition,there was a strong correlation between GC location and the prognosis of postoperative patients.Specifically,patients with“lower”and“middle”GC demonstrated a better prognosis than those with tumors in other categories.CONCLUSION The five clinicopathological indices of gender,age,CEA,CA19-9 and CA72-4 levels exhibit varying degrees of influence on the tumor location.The tumor location correlates with patient prognosis following surgery.展开更多
BACKGROUND Various animal models have been used to explore the pathogenesis of choledochal cysts(CCs),but with little convincing results.Current surgical techniques can achieve satisfactory outcomes for treatment of C...BACKGROUND Various animal models have been used to explore the pathogenesis of choledochal cysts(CCs),but with little convincing results.Current surgical techniques can achieve satisfactory outcomes for treatment of CCs.Consequently,recent studies have focused more on clinical issues rather than basic research.Therefore,we need appropriate animal models to further basic research.AIM To establish an appropriate animal model that may contribute to the investigation of the pathogenesis of CCs.METHODS Eighty-four specific pathogen-free female Sprague-Dawley rats were randomly allocated to a surgical group,sham surgical group,or control group.A rat model of CC was established by partial ligation of the bile duct.The reliability of the model was confirmed by measurements of serum biochemical indices,morpho-logy of common bile ducts of the rats as well as molecular biology experiments in rat and human tissues.RESULTS Dilation classified as mild(diameter,≥1 mm to<3 mm),moderate(≥3 mm to<10 mm),and severe(≥10 mm)was observed in 17,17,and 2 rats in the surgical group,respectively,while no dilation was observed in the control and sham surgical groups.Serum levels of alanine aminotransferase,aspartate aminotrans-ferase,total bilirubin,direct bilirubin,and total bile acids were significantly elevated in the surgical group as compared to the control group 7 d after surgery,while direct bilirubin,total bilirubin,and gamma-glutamyltransferase were further increased 14 d after surgery.Most of the biochemical indices gradually decreased to normal ranges 28 d after surgery.The protein expression trend of signal transducer and activator of transcription 3 in rat model was consistent with the human CC tissues.CONCLUSION The model of partial ligation of the bile duct of juvenile rats could morphologically simulate the cystic or fusiform CC,which may contribute to investigating the pathogenesis of CC.展开更多
AIM:To investigate the value of combined detection of circulating cell-free DNA(cfDNA),a-fetal protein(AFP) and a L-fucosidase(AFU) for diagnosis of hepatocellular carcinoma(HCC).METHODS:Serum samples from 39 HCC pati...AIM:To investigate the value of combined detection of circulating cell-free DNA(cfDNA),a-fetal protein(AFP) and a L-fucosidase(AFU) for diagnosis of hepatocellular carcinoma(HCC).METHODS:Serum samples from 39 HCC patients and 45 normal controls were collected.Branched DNA(bDNA) was used to detect the level of cfDNA,and a receiver operating characteristic curve was employed to evaluate the diagnostic sensitivity,specificity,accuracy,positive predictive value,negative predictive value,positive likelihood ratio,negative likelihood ratio and Youden index,and to assess the diagnostic efficiency and their correlations with the clinicopathological features.AFP and AFU were detected by chemiluminescence and colorimetry,respectively.The significance of combined detection of the three biomarkers was discussed.RESULTS:cfDNA level was increased in 22 of the 39 HCC samples and in 2 of the 45 normal controls.cfDNA level in HCC samples was significantly higher than that in normal controls(P < 0.05).There were significant differences in sex and extra-and intrahepatic metastasis(P < 0.05).There was no significant correlation between cfDNA,AFP and AFU in the detection of HCC.The sensitivity of combined detection of cfDNA with one marker(AFP or AFU) and cfDNA with two markers(AFP and AFU) was 71.8%,87.2% and 89.7% vs 56.4%,53.8% and 66.7% for cfDNA,AFP and AFU used alone,respectively,the difference being statistically significant(P < 0.05).CONCLUSION:Quantitative analysis of cfDNA is sensitive and feasible,and the combined detection of cfDNA with AFP or AFU or both could improve the diagnostic sensitivity for HCC.展开更多
AIM： To investigate the effects of Tat-NEMO-binding domain （NBD） peptide on taurocholate-induced pancreatitis and lipopolysaccharide （LPS）-stimulated AR42J acinus ceils inflammatory response in rats. METHODS： So...AIM： To investigate the effects of Tat-NEMO-binding domain （NBD） peptide on taurocholate-induced pancreatitis and lipopolysaccharide （LPS）-stimulated AR42J acinus ceils inflammatory response in rats. METHODS： Sodium taurocholate （5%） was used to induce the pancreatitis model. Forty-eight rats from the taurocholate group received an intravenous bolus of 13 mg/kg Tat-NBD （wild-type, WT） peptide, Tat- NBD （mutant-type, MT） peptide, NBD peptide or Tat peptide. The pancreatic histopathology was analyzed by hematoxylin staining. LPS was added to the culture medium to stimulate the AR42J cells. For pretreatment, cells were incubated with different peptides for 2 h before LPS stimulation. Expression of IL-1β and TNF-α mRNA was analyzed using a semi-quantitative reverse-transcript polymerase chain reaction （RT-PCR） method. IL-1β and TNF-α protein in culture medium were detected by enzyme linked immunosorbent assay （ELISA）. NF-KB DNA-binding in pancreas was examined by electrophoretic mobility shift assays. P65 expression of AR42J was determined by Strept Actividin-Biotin Complex （SABC） method. RESULTS： Pretreatment with Tat-NBD （WT） peptide at a concentration of 13 mg/kg body wt showed beneficial effect in pancreaitis model. LPS （10 mg/L） resulted in an increase of IL-1β mRNA, IL-1β protein, TNF-α mRNA and TNF-α protein, whereas significantly inhibitory effects were observed when cells were incubated with Tat-NBD （WT）. Consisting with p65 expression decrease analyzed by SABC method, NF-KB DNA-binding activity significantly decreased in Tat-NBD （WT） pretreatment group, especially at the largest dose. No significant changes were found in the control peptide group. CONCLUSION： Our result supports that active NF-KB participates in the pathogenesis of STC-induced acute pancreatitis in rats. Tat-NBD （WT） peptide has anti- inflammatory effects in this model and inhibits the inflammation of acinus simulated by LPS.展开更多
During dynamic walking of biped robots, the underactuated rotating degree of freedom （DOF） emerges between the support foot and the ground, which makes the biped model hybrid and dimension-variant. This paper addres...During dynamic walking of biped robots, the underactuated rotating degree of freedom （DOF） emerges between the support foot and the ground, which makes the biped model hybrid and dimension-variant. This paper addresses the asymptotic orbit stability for dimension-variant hybrid systems （DVHS）. Based on the generalized Poincare map, the stability criterion for DVHS is also presented, and the result is then used to study dynamic walking for a five-link planar biped robot with feet. Time-invariant gait planning and nonlinear control strategy for dynamic walking with fiat feet is also introduced. Simulation results indicate that an asymptotically stable limit cycle of dynamic walking is achieved by the proposed method.展开更多
Fast radio bursts(FRBs)are extragalactic radio transients with millisecond duration and brightness temperature.An FRB-associated X-ray burst(XRB)was recently found to arise from the Galactic magnetar SGR J1935+2154.Fo...Fast radio bursts(FRBs)are extragalactic radio transients with millisecond duration and brightness temperature.An FRB-associated X-ray burst(XRB)was recently found to arise from the Galactic magnetar SGR J1935+2154.Following the model of Dai,in which an FRB may originate from a magnetar encountering an asteroid,we focus on explaining the spectrum of the XRB associated with FRB 200428 from SGR J1935+2154.Collisions between asteroidal fragments and the magnetar surface produce a fireball,which further expands relativistically.Due to the velocity difference among some shells in the fireball,internal shocks would form far away from the magnetar,and further emit X-ray emission.We propose that the FRB-associated XRB can be produced by synchrotron emission from the internal shocks,and then constrain the physical parameters by the observed XRB spectrum.展开更多
Rotor of Synchronous reluctance motor(SynRM)usually has multiple flux barrier structure for the purpose of higher electromagnetic torque and lower torque ripple.Two different strategies are used in this paper for roto...Rotor of Synchronous reluctance motor(SynRM)usually has multiple flux barrier structure for the purpose of higher electromagnetic torque and lower torque ripple.Two different strategies are used in this paper for rotor structure optimization and a compromised strategy for fully squeeze the potential of each related parameters is developed.Performance of resulted rotor structure is evaluated to verify the optimization procedure.展开更多
Since the first successful fabrication in 2004[1],graphene has received tremendous attention due to its extremely simple atomic structure and alluring physical properties.For example,its massless low energy excitation...Since the first successful fabrication in 2004[1],graphene has received tremendous attention due to its extremely simple atomic structure and alluring physical properties.For example,its massless low energy excitations have a linear dispersion and thus its transport property is governed by Dirac equation instead of Schr?dinger equation.These special electronic structures suppress the intra-valley and inter-valley backscatterings,leading to the half-integer and fractional quantum Hall effect[2]under magnetic field and the relativistic quantum tunneling described by the Klein paradox[3].展开更多
A localization method based on distance function of projected features is presented to solve the accuracy reduction or failure problem due to occlusion and blurring caused by smog, when dealing with vision based local...A localization method based on distance function of projected features is presented to solve the accuracy reduction or failure problem due to occlusion and blurring caused by smog, when dealing with vision based localization for target oil and gas wellhead （OGWH）. Firstly, the target OGWH is modeled as a cylinder with marker, and a vector with redundant parameter is used to describe its pose. Secondly, the explicit mapping relationship between the pose vector with redundant parameter and projected features is derived. Then, a 2D-point-to-feature distance function is proposed, as well as its derivative. Finally, based on this distance function and its derivative, an algorithm is proposed to estimate the pose of target OGWH directly according to the 2D image information, and the validity of the method is verified by both synthetic data and real image experiments. The results show that this method is able to accomplish the localization in the case of occlusion and blurring, and its anti-noise ability is good especially with noise ratio of less than 70%.展开更多
基金supported by National Natural Science Foundation of China(Nos.62266054 and 62166050)Key Program of Fundamental Research Project of Yunnan Science and Technology Plan(No.202201AS070021)+2 种基金Yunnan Fundamental Research Projects(No.202401AT070122)Yunnan International Joint Research and Development Center of China-Laos-Thailand Educational Digitalization(No.202203AP140006)Scientific Research Foundation of Yunnan Provincial Department of Education(No.2024Y159).
文摘In the field of intelligent education,the integration of artificial intelligence,especially deep learning technologies,has garnered significant attention.Knowledge tracing(KT)plays a pivotal role in this field by predicting students’future performance through the analysis of historical interaction data,thereby assisting educators in evaluating knowledgemastery and tailoring instructional strategies.Traditional knowledge tracingmethods,largely based on Recurrent Neural Networks(RNNs)and Transformer models,primarily focus on capturing long-term interaction patterns in sequential data.However,these models may neglect crucial short-term dynamics and other relevant features.This paper introduces a novel approach to knowledge tracing by leveraging a pure Multilayer Perceptron(MLP)architecture.We proposeMixerKT,a knowledge tracing model based on theHyperMixer framework,which uniquely integrates global and localMixer feature extractors.This architecture enables more effective extraction of both long-terminteraction trends and recent learning behaviors,addressing limitations in currentmodels thatmay overlook these key aspects.Empirical evaluations on twowidely-used datasets,ASSIS Tments2009 and Algebra2005,demonstrate that MixerKT consistently outperforms several state-of-the-art models,including DKT,SAKT,and Separated Self-Attentive Neural Knowledge Tracing(SAINT).Specifically,MixerKT achieves higher prediction accuracy,highlighting its effectiveness in capturing the nuances of learners’knowledge states.These results indicate that our model provides a more comprehensive representation of student learning patterns,enhancing the ability to predict future performance with greater precision.
基金Supported by the National Natural Science Foundation of China,No.82473195Natural Science Foundation of Zhejiang Province,No.LTGY23H160018+2 种基金Zhejiang Medical and Health Science and Technology Program,No.2024KY789Beijing Science and Technology Innovation Medical Development Foundation,No.KC2023-JX-0270-07National Natural Science Foundation of China,No.32370797.
文摘BACKGROUND Gastric cancer(GC)is a highly prevalent gastrointestinal tract tumor.Several trials have demonstrated that the location of GC can affect patient prognosis.However,the factors determining tumor location remain unclear.AIM To investigate the tumor location of patients,we went on to study the influencing factors that lead to changes in the location of GC.METHODS A retrospective evaluation was carried out on 3287 patients who underwent gastrectomy for GC in Zhejiang Cancer Hospital.The patients were followed up post-diagnosis and post-gastrectomy.The clinicopathological variables and overall survival of the patients were recorded.By analyzing the location of GC,the tumor location was divided into four categories:“Upper”,“middle”,“lower”,and“total”.Statistical software was utilized to analyze the relationship of each variable with the location of GC.RESULTS A total of 3287 patients were included in this study.The clinicopathological indices of gender,age,serum levels of carcinoembryonic antigen(CEA),carbohydrate antigen(CA19-9)and CA72-4 levels,were significantly associated with tumor location in patients with GC.In addition,there was a strong correlation between GC location and the prognosis of postoperative patients.Specifically,patients with“lower”and“middle”GC demonstrated a better prognosis than those with tumors in other categories.CONCLUSION The five clinicopathological indices of gender,age,CEA,CA19-9 and CA72-4 levels exhibit varying degrees of influence on the tumor location.The tumor location correlates with patient prognosis following surgery.
基金the Key R&D Program of Zhejiang,No.2023C03029Health Science and Technology Plan of Zhejiang Province,No.2022RC201Zhejiang Provincial Natural Science Foundation Project,No.LY20H030007.
文摘BACKGROUND Various animal models have been used to explore the pathogenesis of choledochal cysts(CCs),but with little convincing results.Current surgical techniques can achieve satisfactory outcomes for treatment of CCs.Consequently,recent studies have focused more on clinical issues rather than basic research.Therefore,we need appropriate animal models to further basic research.AIM To establish an appropriate animal model that may contribute to the investigation of the pathogenesis of CCs.METHODS Eighty-four specific pathogen-free female Sprague-Dawley rats were randomly allocated to a surgical group,sham surgical group,or control group.A rat model of CC was established by partial ligation of the bile duct.The reliability of the model was confirmed by measurements of serum biochemical indices,morpho-logy of common bile ducts of the rats as well as molecular biology experiments in rat and human tissues.RESULTS Dilation classified as mild(diameter,≥1 mm to<3 mm),moderate(≥3 mm to<10 mm),and severe(≥10 mm)was observed in 17,17,and 2 rats in the surgical group,respectively,while no dilation was observed in the control and sham surgical groups.Serum levels of alanine aminotransferase,aspartate aminotrans-ferase,total bilirubin,direct bilirubin,and total bile acids were significantly elevated in the surgical group as compared to the control group 7 d after surgery,while direct bilirubin,total bilirubin,and gamma-glutamyltransferase were further increased 14 d after surgery.Most of the biochemical indices gradually decreased to normal ranges 28 d after surgery.The protein expression trend of signal transducer and activator of transcription 3 in rat model was consistent with the human CC tissues.CONCLUSION The model of partial ligation of the bile duct of juvenile rats could morphologically simulate the cystic or fusiform CC,which may contribute to investigating the pathogenesis of CC.
文摘AIM:To investigate the value of combined detection of circulating cell-free DNA(cfDNA),a-fetal protein(AFP) and a L-fucosidase(AFU) for diagnosis of hepatocellular carcinoma(HCC).METHODS:Serum samples from 39 HCC patients and 45 normal controls were collected.Branched DNA(bDNA) was used to detect the level of cfDNA,and a receiver operating characteristic curve was employed to evaluate the diagnostic sensitivity,specificity,accuracy,positive predictive value,negative predictive value,positive likelihood ratio,negative likelihood ratio and Youden index,and to assess the diagnostic efficiency and their correlations with the clinicopathological features.AFP and AFU were detected by chemiluminescence and colorimetry,respectively.The significance of combined detection of the three biomarkers was discussed.RESULTS:cfDNA level was increased in 22 of the 39 HCC samples and in 2 of the 45 normal controls.cfDNA level in HCC samples was significantly higher than that in normal controls(P < 0.05).There were significant differences in sex and extra-and intrahepatic metastasis(P < 0.05).There was no significant correlation between cfDNA,AFP and AFU in the detection of HCC.The sensitivity of combined detection of cfDNA with one marker(AFP or AFU) and cfDNA with two markers(AFP and AFU) was 71.8%,87.2% and 89.7% vs 56.4%,53.8% and 66.7% for cfDNA,AFP and AFU used alone,respectively,the difference being statistically significant(P < 0.05).CONCLUSION:Quantitative analysis of cfDNA is sensitive and feasible,and the combined detection of cfDNA with AFP or AFU or both could improve the diagnostic sensitivity for HCC.
基金Supported by The Natural Science Foundation, No. 04009624
文摘AIM： To investigate the effects of Tat-NEMO-binding domain （NBD） peptide on taurocholate-induced pancreatitis and lipopolysaccharide （LPS）-stimulated AR42J acinus ceils inflammatory response in rats. METHODS： Sodium taurocholate （5%） was used to induce the pancreatitis model. Forty-eight rats from the taurocholate group received an intravenous bolus of 13 mg/kg Tat-NBD （wild-type, WT） peptide, Tat- NBD （mutant-type, MT） peptide, NBD peptide or Tat peptide. The pancreatic histopathology was analyzed by hematoxylin staining. LPS was added to the culture medium to stimulate the AR42J cells. For pretreatment, cells were incubated with different peptides for 2 h before LPS stimulation. Expression of IL-1β and TNF-α mRNA was analyzed using a semi-quantitative reverse-transcript polymerase chain reaction （RT-PCR） method. IL-1β and TNF-α protein in culture medium were detected by enzyme linked immunosorbent assay （ELISA）. NF-KB DNA-binding in pancreas was examined by electrophoretic mobility shift assays. P65 expression of AR42J was determined by Strept Actividin-Biotin Complex （SABC） method. RESULTS： Pretreatment with Tat-NBD （WT） peptide at a concentration of 13 mg/kg body wt showed beneficial effect in pancreaitis model. LPS （10 mg/L） resulted in an increase of IL-1β mRNA, IL-1β protein, TNF-α mRNA and TNF-α protein, whereas significantly inhibitory effects were observed when cells were incubated with Tat-NBD （WT）. Consisting with p65 expression decrease analyzed by SABC method, NF-KB DNA-binding activity significantly decreased in Tat-NBD （WT） pretreatment group, especially at the largest dose. No significant changes were found in the control peptide group. CONCLUSION： Our result supports that active NF-KB participates in the pathogenesis of STC-induced acute pancreatitis in rats. Tat-NBD （WT） peptide has anti- inflammatory effects in this model and inhibits the inflammation of acinus simulated by LPS.
基金the National Natural Science Foundation of China (No. 50575119)the 863 Program(No. 2006AA04Z253)the Ph.D.Programs Foundation of Ministry of Education of China(No. 20060003026)
文摘During dynamic walking of biped robots, the underactuated rotating degree of freedom （DOF） emerges between the support foot and the ground, which makes the biped model hybrid and dimension-variant. This paper addresses the asymptotic orbit stability for dimension-variant hybrid systems （DVHS）. Based on the generalized Poincare map, the stability criterion for DVHS is also presented, and the result is then used to study dynamic walking for a five-link planar biped robot with feet. Time-invariant gait planning and nonlinear control strategy for dynamic walking with fiat feet is also introduced. Simulation results indicate that an asymptotically stable limit cycle of dynamic walking is achieved by the proposed method.
基金supported by the National Key Research and Development Program of China(Grant Nos.2017YFA0402600,2018YFA0404204)the National SKA Program of China(Grant No.2020SKA0120300)+9 种基金the National Natural Science Foundation of China(NSFC,Grant Nos.11833003,U2038105)supported by the National Natural Science Foundation of China(NSFC,Grant No.12003028)support from the National Natural Science Foundation of China(NSFC,Grant No.U1838113)the National Natural Science Foundation of China(NSFC,Grant Nos.11833003 and U2038105)the Program for Innovative Talents,Entrepreneur in JiangsuYunnan University(Grant No.C176220100087)support by Fundamental Research Funds for the Central Universities(14380046)the National Key Research and Development Programs of China(2018YFA0404204)the science research grants from the China Manned Space Project with NO.CMS-CSST-2021-B11the Program for Innovative Talents,Entrepreneur in Jiangsu。
文摘Fast radio bursts(FRBs)are extragalactic radio transients with millisecond duration and brightness temperature.An FRB-associated X-ray burst(XRB)was recently found to arise from the Galactic magnetar SGR J1935+2154.Following the model of Dai,in which an FRB may originate from a magnetar encountering an asteroid,we focus on explaining the spectrum of the XRB associated with FRB 200428 from SGR J1935+2154.Collisions between asteroidal fragments and the magnetar surface produce a fireball,which further expands relativistically.Due to the velocity difference among some shells in the fireball,internal shocks would form far away from the magnetar,and further emit X-ray emission.We propose that the FRB-associated XRB can be produced by synchrotron emission from the internal shocks,and then constrain the physical parameters by the observed XRB spectrum.
文摘Rotor of Synchronous reluctance motor(SynRM)usually has multiple flux barrier structure for the purpose of higher electromagnetic torque and lower torque ripple.Two different strategies are used in this paper for rotor structure optimization and a compromised strategy for fully squeeze the potential of each related parameters is developed.Performance of resulted rotor structure is evaluated to verify the optimization procedure.
基金supported by the National Natural Science Foundation of China(12374054,12022415,11974056,12274187,and 12247101)。
文摘Since the first successful fabrication in 2004[1],graphene has received tremendous attention due to its extremely simple atomic structure and alluring physical properties.For example,its massless low energy excitations have a linear dispersion and thus its transport property is governed by Dirac equation instead of Schr?dinger equation.These special electronic structures suppress the intra-valley and inter-valley backscatterings,leading to the half-integer and fractional quantum Hall effect[2]under magnetic field and the relativistic quantum tunneling described by the Klein paradox[3].
基金supported by National Natural Science Foundation of China(No.61403226)the State Key Laboratory of Tribology of China(No.SKLT09A03)
文摘A localization method based on distance function of projected features is presented to solve the accuracy reduction or failure problem due to occlusion and blurring caused by smog, when dealing with vision based localization for target oil and gas wellhead （OGWH）. Firstly, the target OGWH is modeled as a cylinder with marker, and a vector with redundant parameter is used to describe its pose. Secondly, the explicit mapping relationship between the pose vector with redundant parameter and projected features is derived. Then, a 2D-point-to-feature distance function is proposed, as well as its derivative. Finally, based on this distance function and its derivative, an algorithm is proposed to estimate the pose of target OGWH directly according to the 2D image information, and the validity of the method is verified by both synthetic data and real image experiments. The results show that this method is able to accomplish the localization in the case of occlusion and blurring, and its anti-noise ability is good especially with noise ratio of less than 70%.
