We study a finite number of independent random walks with subexponentially distributed increments and negative drifts.We extend the one-dimensional results to finite and fully general stopping times.Assuming that the ...We study a finite number of independent random walks with subexponentially distributed increments and negative drifts.We extend the one-dimensional results to finite and fully general stopping times.Assuming that the distribution of the lengths of these intervals is relatively light compared to the distribution of the increments of the random walks,we derive the asymptotic tail distribution of the partial maximum sum over the random time interval.展开更多
Objective:The incidence and mortality of colorectal carcinoma(CRC)continue to rise globally,highlighting the need to identify modifiable risk factors for early detection and prevention.Previous studies have demonstrat...Objective:The incidence and mortality of colorectal carcinoma(CRC)continue to rise globally,highlighting the need to identify modifiable risk factors for early detection and prevention.Previous studies have demonstrated significant associations between CRC risk and various serum metabolites as well as inflammatory cytokines;however,due to limitations in study design and potential confounding factors,the causal relationships remain unclear.This study aims to investigate the causal relationships between inflammatory cytokines,serum metabolites,and CRC risk,providing a theoretical basis for the development of novel early diagnostic biomarkers and therapeutic targets.Methods:A two-sample Mendelian randomization(MR)design was applied using summary statistics from genome-wide association studies(GWAS).Instrumental variables(IVs)were derived from:1)metabolomics GWAS data of 1400 serum metabolites(n=8299);2)cytokine GWAS data of 91 inflammatory factors(n=14824);and 3)CRC risk data from the FinnGen consortium(6847 cases and 314193 controls).The primary analysis was conducted using the inverse-variance weighted(IVW)method,with sensitivity analyses performed using MR Egger regression and the weighted median method.Effect estimates including odds ratios(OR),95%confidence intervals(CI),and false discovery rates(FDR)were calculated.Results:MR analysis indicated that higher levels of axin-1(AXIN1)(OR=0.84195%CI 0.714 to 0.991)and Fms-related tyrosine kinase 3 ligand(Flt3L)(OR=0.916,95%CI 0.844 to 0.994)were associated with a reduced risk of CRC.In contrast,higher levels of Delta/Notchlike epidermal growth factor-related receptor(DNER)(OR=1.119,95%CI 1.009 to 1.241)and vascular endothelial growth factor A(VEGF-A)(OR=1.078,95%CI 1.011 to 1.150)were associated with an increased risk of CRC(all P<0.05).Metabolomics association analysis further identified 144 serum metabolites significantly correlated with these four key inflammatory cytokines(FDR<0.05),suggesting that they may regulate CRC risk through inflammatory pathways.Conclusion:Specific inflammatory cytokines and serum metabolites have causal relationships with the risk of CRC.These findings provide insights for further exploration of potential risk factors and the development of effective prevention strategies for CRC.展开更多
In this paper,by utilizing the Marcinkiewicz-Zygmund inequality and Rosenthal-type inequality of negatively superadditive dependent(NSD)random arrays and truncated method,we investigate the complete f-moment convergen...In this paper,by utilizing the Marcinkiewicz-Zygmund inequality and Rosenthal-type inequality of negatively superadditive dependent(NSD)random arrays and truncated method,we investigate the complete f-moment convergence of NSD random variables.We establish and improve a general result on the complete f-moment convergence for Sung’s type randomly weighted sums of NSD random variables under some general assumptions.As an application,we show the complete consistency for the randomly weighted estimator in a nonparametric regression model based on NSD errors.展开更多
OBJECTIVE To investigate the intervention effects of tissue-bone homeostasis manipulation(TBHM)on peripatellar biomechanical parameters and knee joint function in knee osteoarthritis(KOA)patients.METHODS Sixty patient...OBJECTIVE To investigate the intervention effects of tissue-bone homeostasis manipulation(TBHM)on peripatellar biomechanical parameters and knee joint function in knee osteoarthritis(KOA)patients.METHODS Sixty patients with KOA(Kellgren-Lawrence gradeⅡ-Ⅲ)were recruited from the Acupuncture-Moxibustion Rehabilitation Department,Anhui University of Chinese Medicine between October 2024 and May 2025.Participants were randomized into a TBHM group(n=30)or a transcutaneous electrical neuromuscular stimulation(TENS)group(n=30).Using two-way repeated measures ANOVA,biomechanical indicators,including rectus femoris tension,vastus medialis tension,vastus lateralis tension,patellar ligament tension,lateral patellar displacement(LPD),medial patellar displacement(MPD),normalized patellar mobility(LPD/patellar width[PW],MPD/PW),knee flexion range of motion,and functional indicators,including KOOS subscales,time up and go test(TUGT),were compared between groups at baseline and after 6 weeks of intervention.RESULTS After intervention,all biomechanical and knee joint function indicators in the TBHM group were significantly improved(P<0.05,P<0.01),while only the vastus medialis tension,TUGT and KOOS Pain,ADL and QoL scores in the control group were significantly improved(P<0.01).The improvement amplitudes of biomechanical indicators in the TBHM group,including rectus femoris tension,vastus lateralis tension,patellar ligament tension,MPD/PW,LPD/PW and knee flexion range of motion were better than those in the control group(P<0.05,P<0.01).In the functional evaluation,the interaction effects of the TBHM group in all dimensions of the KOOS score and TUGT were statistically significant(P<0.05,P<0.01).Post-hoc simple effect analysis confirmed that there were significant differences in the above indicators between the two groups after intervention(P<0.05),and all indicators showed a significant main effect of time(P<0.01),suggesting that the intervention measures had continuous and cumulative curative effects.CONCLUSION TBHM effectively improves joint function and quality of life in KOA patients by restoring dynamic equilibrium in soft tissue tension and patellar mobility,ultimately achieving the therapeutic goal of concurrent tissue-bone management.展开更多
Objective:Gut microbiota(GM)and blood metabolites are associated with the development of urticaria,yet their specific causal relationships in East Asian populations remain unclear.This study aims to elucidate the caus...Objective:Gut microbiota(GM)and blood metabolites are associated with the development of urticaria,yet their specific causal relationships in East Asian populations remain unclear.This study aims to elucidate the causal and mediating relationships among GM,blood metabolites,and urticaria in East Asians using Mendelian randomization(MR)analysis.Methods:Summary-level statistics for 500 GM taxa,112 blood metabolites,and urticaria were obtained from publicly available Genome-Wide Association Studies(GWAS)datasets.Bidirectional MR analyses were performed to examine causal associations among the GM,blood metabolites,and urticaria.The inverse variance weighted(IVW)method served as the primary analytical approach,supplemented by MR-Egger,weighted median,simple mode,and weighted mode methods.Sensitivity analyses included heterogeneity tests,horizontal pleiotropy assessments,and leave-one-out analyses.Mediation analysis was conducted to evaluate the potential mediating effects of blood metabolites on the causal pathways between GM and urticaria.Results:MR analyses identified 12 GM taxa exhibiting significant causal effects on urticaria susceptibility.Nine taxa,such as MF0017_galactose_degradation(OR=1.461,95%CI 1.098 to 1.944,P=0.009),were associated with increased urticaria risk.Three taxa,such as MF0001_arabinoxylan_degradation(OR=0.846,95%CI 0.737 to 0.973,P=0.019),showed protective effects with increased abundance.Additionally,6 blood metabolites demonstrated causal associations with urticaria.Notably,the risk of developing urticaria increases with rising fasting plasma glucose(FPG)levels(OR=1.971,95%CI 1.089 to 3.567,P=0.025).Mediation analysis further demonstrated that FPG partially mediated the protective effect of MF0001_arabinoxylan_degradation on urticaria,accounting for 11.30%of the total effect.Conclusion:This study has delineated specific GM taxa and blood metabolites that hold causal relevance to urticaria in East Asian populations.Notably,arabinogalactan degradation potentially mitigates urticaria risk via reducing FPG concentrations,offering genetic evidence to support therapeutic strategies targeting GM modulation and glucose regulation.展开更多
In this paper,large deviations principle(LDP)and moderate deviations principle(MDP)of record numbers in random walks are studied under certain conditions.The results show that the rate functions of LDP and MDP are dif...In this paper,large deviations principle(LDP)and moderate deviations principle(MDP)of record numbers in random walks are studied under certain conditions.The results show that the rate functions of LDP and MDP are different from those of weak record numbers,which are interesting complements of the conclusions by Li and Yao[1].展开更多
The complete convergence for weighted sums of sequences of independent,identically distributed random variables under sublinear expectation space is studied.By moment inequality and truncation methods,we establish the...The complete convergence for weighted sums of sequences of independent,identically distributed random variables under sublinear expectation space is studied.By moment inequality and truncation methods,we establish the equivalent conditions of complete convergence for weighted sums of sequences of independent,identically distributed random variables under sublinear expectation space.The results complement the corresponding results in probability space to those for sequences of independent,identically distributed random variables under sublinear expectation space.展开更多
Missiles provide long-range precision strike capabilities and have become a cornerstone of modern warfare.The contrail clouds formed by missile during their active flight phase present significant chal-lenges to high-...Missiles provide long-range precision strike capabilities and have become a cornerstone of modern warfare.The contrail clouds formed by missile during their active flight phase present significant chal-lenges to high-altitude environmental observation and target detection and tracking.Existing studies primarily focus on specific airspace regions,leaving critical gaps in understanding the effects of long dispersion times,wide altitude ranges,and variable atmospheric conditions on missile contrail clouds.To address these gaps,this article develops a numerical method based on the Lagrangian random walk model,which incorporates various velocity variation terms,including particle velocity caused by the difference of wind field,by the thermal motion of local gas molecules and by random collisions between contrail cloud particles to capture the influence of environmental wind fields,atmospheric conditions,and particle concentrations on the motion of contrail cloud particles.A general coordinate system aligned with the missile's flight trajectory is employed to represent particle distribution characteristics.The proposed method is in good agreement with the conducted experiments as well as with the available numerical simulations.The results demonstrate that the proposed model effectively simulates the dispersion state of contrail clouds,accurately reflecting the impact of large-scale wind field variations and altitude changes with high computational efficiency.Additionally,simulation results indicate that the increased distance between gas molecules in rarefied environments facilitates enhanced particle dispersion,while larger particles exhibit a faster dispersion rate due to their greater mass.展开更多
Random Waypoint模型是自组网经常使用的移动模型,对这种移动模型下运动节点的空间概率分布进行了研究,得到了一维与二维区域的运动节点空间概率分布的精确公式,解决了自组网仿真模型的一个遗留问题·研究结果为基于Random Waypoin...Random Waypoint模型是自组网经常使用的移动模型,对这种移动模型下运动节点的空间概率分布进行了研究,得到了一维与二维区域的运动节点空间概率分布的精确公式,解决了自组网仿真模型的一个遗留问题·研究结果为基于Random Waypoint移动模型的自组网理论的推导、证明、仿真与应用提供了理论依据,对基于该模型的自组网仿真具有实践指导意义·展开更多
Unstructured P2P has power-law link distribution, and the random walk in power-law networks is analyzed. The analysis results show that the probability that a random walker walks through the high degree nodes is high ...Unstructured P2P has power-law link distribution, and the random walk in power-law networks is analyzed. The analysis results show that the probability that a random walker walks through the high degree nodes is high in the power-law network, and the information on the high degree nodes can be easily found through random walk. Random walk spread and random walk search method （RWSS） is proposed based on the analysis result. Simulation results show that RWSS achieves high success rates at low cost and is robust to high degree node failure.展开更多
Remaining useful life(RUL)prediction is one of the most crucial components in prognostics and health management(PHM)of aero-engines.This paper proposes an RUL prediction method of aero-engines considering the randomne...Remaining useful life(RUL)prediction is one of the most crucial components in prognostics and health management(PHM)of aero-engines.This paper proposes an RUL prediction method of aero-engines considering the randomness of failure threshold.Firstly,a random-coefficient regression(RCR)model is used to model the degradation process of aeroengines.Then,the RUL distribution based on fixed failure threshold is derived.The prior parameters of the degradation model are calculated by a two-step maximum likelihood estimation(MLE)method and the random coefficient is updated in real time under the Bayesian framework.The failure threshold in this paper is defined by the actual degradation process of aeroengines.After that,a expectation maximization(EM)algorithm is proposed to estimate the underlying failure threshold of aeroengines.In addition,the conditional probability is used to satisfy the limitation of failure threshold.Then,based on above results,an analytical expression of RUL distribution of aero-engines based on the RCR model considering random failure threshold(RFT)is derived in a closed-form.Finally,a case study of turbofan engine is used to demonstrate the effectiveness and superiority of the RUL prediction method and the parameters estimation method of failure threshold proposed.展开更多
Objective This study was to evaluate the efficacy and safety of a short acting reduced dose fibrinolytic regimen to promote early infarct related artery (IRA) patency for acyute myocardial infarction (AMI) patients re...Objective This study was to evaluate the efficacy and safety of a short acting reduced dose fibrinolytic regimen to promote early infarct related artery (IRA) patency for acyute myocardial infarction (AMI) patients referred for percutaneous coronary intervention (PCI).Methods Following aspirin and heparin, 166 patients were randomized to a 50 mg bolus of recombinant tissue type plasminogen activator(rt PA) or to a same volume sodium chloride injection followed by immediate primary PCI. The end points included patency rates on catheterization laboratory (cath lab) arrival, revascularization results when PCI was performed, complication rates, left ventricular function and restored patency rate following PCI. Results Patency on cath lab arrival was 64% with rt PA (34% TIMI 3,30% TIMI 2), while 31% of placebo (13% TIMI 3, 18% TIMI 2). There was no difference in the restored TIMI 3 rates of IRA between the two groups (85% vs 87%). No difference were observed in stroke or major bleeding. Left ventricular function was similar in both groups (52±9% vs 50±8%), but left ventricular ejection fraction fraction (LVEF) was higher with patent IRA (TIMI 3) on cath lab arrival than that of others (56±12% vs 48±10%).Conclusions Strategy thrombolytic regimens were compatible with subsequent PCI lead to more frequenc early recanalization (before cath lab arrival), which facilitates greater left ventricular function preservation with no augmentation of adverse events.展开更多
In this research combustion of aluminum dust particles in a quiescent medium with spatially discrete sources distributed in a random way was studied by a numerical approach.A new thermal model was generated to estimat...In this research combustion of aluminum dust particles in a quiescent medium with spatially discrete sources distributed in a random way was studied by a numerical approach.A new thermal model was generated to estimate flame propagation speed in a lean/rich reaction medium.Flame speed for different particle diameters and the effects of various oxidizers such as carbon dioxide and oxygen on flame speed were studied.Nitrogen was considered the inert gas.In addition,the quenching distance and the minimum ignition energy(MIE) were studied as a function of dust concentration.Different burning time models for aluminum were employed and their results were compared with each other.The model was based on conduction heat transfer mechanism using the heat point source method.The combustion of single-particle was first studied and the solution was presented.Then the dust combustion was investigated using the superposition principle to include the effects of surrounding particles.It is found that larger particles have higher values of quenching distance in comparison with smaller particles in an assumed dust concentration.With the increase of dust concentration the value of MIE would be decreased for an assumed particle diameter.Considering random discrete heat sources method,the obtained results of random distribution of fuel particles in space provide closer and realistic predictions of the combustion physics of aluminum dust flame as compared with the experimental findings.展开更多
基金supported by Xinjiang Normal University Outstanding Young Teacher Research Launch Fund Project(Grant No.XJNU202116)。
文摘We study a finite number of independent random walks with subexponentially distributed increments and negative drifts.We extend the one-dimensional results to finite and fully general stopping times.Assuming that the distribution of the lengths of these intervals is relatively light compared to the distribution of the increments of the random walks,we derive the asymptotic tail distribution of the partial maximum sum over the random time interval.
基金supported by the Natural Science Foundation of Hunan Province (2022JJ30987)the Key Research and Development Project of Hunan Province (2024JK2107),China。
文摘Objective:The incidence and mortality of colorectal carcinoma(CRC)continue to rise globally,highlighting the need to identify modifiable risk factors for early detection and prevention.Previous studies have demonstrated significant associations between CRC risk and various serum metabolites as well as inflammatory cytokines;however,due to limitations in study design and potential confounding factors,the causal relationships remain unclear.This study aims to investigate the causal relationships between inflammatory cytokines,serum metabolites,and CRC risk,providing a theoretical basis for the development of novel early diagnostic biomarkers and therapeutic targets.Methods:A two-sample Mendelian randomization(MR)design was applied using summary statistics from genome-wide association studies(GWAS).Instrumental variables(IVs)were derived from:1)metabolomics GWAS data of 1400 serum metabolites(n=8299);2)cytokine GWAS data of 91 inflammatory factors(n=14824);and 3)CRC risk data from the FinnGen consortium(6847 cases and 314193 controls).The primary analysis was conducted using the inverse-variance weighted(IVW)method,with sensitivity analyses performed using MR Egger regression and the weighted median method.Effect estimates including odds ratios(OR),95%confidence intervals(CI),and false discovery rates(FDR)were calculated.Results:MR analysis indicated that higher levels of axin-1(AXIN1)(OR=0.84195%CI 0.714 to 0.991)and Fms-related tyrosine kinase 3 ligand(Flt3L)(OR=0.916,95%CI 0.844 to 0.994)were associated with a reduced risk of CRC.In contrast,higher levels of Delta/Notchlike epidermal growth factor-related receptor(DNER)(OR=1.119,95%CI 1.009 to 1.241)and vascular endothelial growth factor A(VEGF-A)(OR=1.078,95%CI 1.011 to 1.150)were associated with an increased risk of CRC(all P<0.05).Metabolomics association analysis further identified 144 serum metabolites significantly correlated with these four key inflammatory cytokines(FDR<0.05),suggesting that they may regulate CRC risk through inflammatory pathways.Conclusion:Specific inflammatory cytokines and serum metabolites have causal relationships with the risk of CRC.These findings provide insights for further exploration of potential risk factors and the development of effective prevention strategies for CRC.
基金supported by the National Social Science Fundation(Grant No.21BTJ040)the Project of Outstanding Young People in University of Anhui Province(Grant Nos.2023AH020037,SLXY2024A001).
文摘In this paper,by utilizing the Marcinkiewicz-Zygmund inequality and Rosenthal-type inequality of negatively superadditive dependent(NSD)random arrays and truncated method,we investigate the complete f-moment convergence of NSD random variables.We establish and improve a general result on the complete f-moment convergence for Sung’s type randomly weighted sums of NSD random variables under some general assumptions.As an application,we show the complete consistency for the randomly weighted estimator in a nonparametric regression model based on NSD errors.
文摘OBJECTIVE To investigate the intervention effects of tissue-bone homeostasis manipulation(TBHM)on peripatellar biomechanical parameters and knee joint function in knee osteoarthritis(KOA)patients.METHODS Sixty patients with KOA(Kellgren-Lawrence gradeⅡ-Ⅲ)were recruited from the Acupuncture-Moxibustion Rehabilitation Department,Anhui University of Chinese Medicine between October 2024 and May 2025.Participants were randomized into a TBHM group(n=30)or a transcutaneous electrical neuromuscular stimulation(TENS)group(n=30).Using two-way repeated measures ANOVA,biomechanical indicators,including rectus femoris tension,vastus medialis tension,vastus lateralis tension,patellar ligament tension,lateral patellar displacement(LPD),medial patellar displacement(MPD),normalized patellar mobility(LPD/patellar width[PW],MPD/PW),knee flexion range of motion,and functional indicators,including KOOS subscales,time up and go test(TUGT),were compared between groups at baseline and after 6 weeks of intervention.RESULTS After intervention,all biomechanical and knee joint function indicators in the TBHM group were significantly improved(P<0.05,P<0.01),while only the vastus medialis tension,TUGT and KOOS Pain,ADL and QoL scores in the control group were significantly improved(P<0.01).The improvement amplitudes of biomechanical indicators in the TBHM group,including rectus femoris tension,vastus lateralis tension,patellar ligament tension,MPD/PW,LPD/PW and knee flexion range of motion were better than those in the control group(P<0.05,P<0.01).In the functional evaluation,the interaction effects of the TBHM group in all dimensions of the KOOS score and TUGT were statistically significant(P<0.05,P<0.01).Post-hoc simple effect analysis confirmed that there were significant differences in the above indicators between the two groups after intervention(P<0.05),and all indicators showed a significant main effect of time(P<0.01),suggesting that the intervention measures had continuous and cumulative curative effects.CONCLUSION TBHM effectively improves joint function and quality of life in KOA patients by restoring dynamic equilibrium in soft tissue tension and patellar mobility,ultimately achieving the therapeutic goal of concurrent tissue-bone management.
基金supported by the Natural Science Foundation of Hunan Province,China(2024JJ7627).
文摘Objective:Gut microbiota(GM)and blood metabolites are associated with the development of urticaria,yet their specific causal relationships in East Asian populations remain unclear.This study aims to elucidate the causal and mediating relationships among GM,blood metabolites,and urticaria in East Asians using Mendelian randomization(MR)analysis.Methods:Summary-level statistics for 500 GM taxa,112 blood metabolites,and urticaria were obtained from publicly available Genome-Wide Association Studies(GWAS)datasets.Bidirectional MR analyses were performed to examine causal associations among the GM,blood metabolites,and urticaria.The inverse variance weighted(IVW)method served as the primary analytical approach,supplemented by MR-Egger,weighted median,simple mode,and weighted mode methods.Sensitivity analyses included heterogeneity tests,horizontal pleiotropy assessments,and leave-one-out analyses.Mediation analysis was conducted to evaluate the potential mediating effects of blood metabolites on the causal pathways between GM and urticaria.Results:MR analyses identified 12 GM taxa exhibiting significant causal effects on urticaria susceptibility.Nine taxa,such as MF0017_galactose_degradation(OR=1.461,95%CI 1.098 to 1.944,P=0.009),were associated with increased urticaria risk.Three taxa,such as MF0001_arabinoxylan_degradation(OR=0.846,95%CI 0.737 to 0.973,P=0.019),showed protective effects with increased abundance.Additionally,6 blood metabolites demonstrated causal associations with urticaria.Notably,the risk of developing urticaria increases with rising fasting plasma glucose(FPG)levels(OR=1.971,95%CI 1.089 to 3.567,P=0.025).Mediation analysis further demonstrated that FPG partially mediated the protective effect of MF0001_arabinoxylan_degradation on urticaria,accounting for 11.30%of the total effect.Conclusion:This study has delineated specific GM taxa and blood metabolites that hold causal relevance to urticaria in East Asian populations.Notably,arabinogalactan degradation potentially mitigates urticaria risk via reducing FPG concentrations,offering genetic evidence to support therapeutic strategies targeting GM modulation and glucose regulation.
基金supported by the National Natural Science Foundation of China(Grant No.11671145)the Science and Technology Commission of Shanghai Municipality(Grant No.18dz2271000).
文摘In this paper,large deviations principle(LDP)and moderate deviations principle(MDP)of record numbers in random walks are studied under certain conditions.The results show that the rate functions of LDP and MDP are different from those of weak record numbers,which are interesting complements of the conclusions by Li and Yao[1].
基金supported by Doctoral Scientific Research Starting Foundation of Jingdezhen Ceramic University(Grant No.102/01003002031)Re-accompanying Funding Project of Academic Achievements of Jingdezhen Ceramic University(Grant Nos.215/20506277,215/20506341)。
文摘The complete convergence for weighted sums of sequences of independent,identically distributed random variables under sublinear expectation space is studied.By moment inequality and truncation methods,we establish the equivalent conditions of complete convergence for weighted sums of sequences of independent,identically distributed random variables under sublinear expectation space.The results complement the corresponding results in probability space to those for sequences of independent,identically distributed random variables under sublinear expectation space.
文摘Missiles provide long-range precision strike capabilities and have become a cornerstone of modern warfare.The contrail clouds formed by missile during their active flight phase present significant chal-lenges to high-altitude environmental observation and target detection and tracking.Existing studies primarily focus on specific airspace regions,leaving critical gaps in understanding the effects of long dispersion times,wide altitude ranges,and variable atmospheric conditions on missile contrail clouds.To address these gaps,this article develops a numerical method based on the Lagrangian random walk model,which incorporates various velocity variation terms,including particle velocity caused by the difference of wind field,by the thermal motion of local gas molecules and by random collisions between contrail cloud particles to capture the influence of environmental wind fields,atmospheric conditions,and particle concentrations on the motion of contrail cloud particles.A general coordinate system aligned with the missile's flight trajectory is employed to represent particle distribution characteristics.The proposed method is in good agreement with the conducted experiments as well as with the available numerical simulations.The results demonstrate that the proposed model effectively simulates the dispersion state of contrail clouds,accurately reflecting the impact of large-scale wind field variations and altitude changes with high computational efficiency.Additionally,simulation results indicate that the increased distance between gas molecules in rarefied environments facilitates enhanced particle dispersion,while larger particles exhibit a faster dispersion rate due to their greater mass.
基金the Defense Pre-Research Project ofthe"Tenth Five-Year-Plan"of China ( No.41316.4.2) the National Defense Basic Research Foundation under grant No.51416040101HT0117.
文摘Unstructured P2P has power-law link distribution, and the random walk in power-law networks is analyzed. The analysis results show that the probability that a random walker walks through the high degree nodes is high in the power-law network, and the information on the high degree nodes can be easily found through random walk. Random walk spread and random walk search method （RWSS） is proposed based on the analysis result. Simulation results show that RWSS achieves high success rates at low cost and is robust to high degree node failure.
基金supported by the National Natural Science Foundation of China(61703410,61873175,62073336,61873273,61773386,61922-089)the Basic Research Plan of Shaanxi Natural Science Foundation of China(2022JM-376).
文摘Remaining useful life(RUL)prediction is one of the most crucial components in prognostics and health management(PHM)of aero-engines.This paper proposes an RUL prediction method of aero-engines considering the randomness of failure threshold.Firstly,a random-coefficient regression(RCR)model is used to model the degradation process of aeroengines.Then,the RUL distribution based on fixed failure threshold is derived.The prior parameters of the degradation model are calculated by a two-step maximum likelihood estimation(MLE)method and the random coefficient is updated in real time under the Bayesian framework.The failure threshold in this paper is defined by the actual degradation process of aeroengines.After that,a expectation maximization(EM)algorithm is proposed to estimate the underlying failure threshold of aeroengines.In addition,the conditional probability is used to satisfy the limitation of failure threshold.Then,based on above results,an analytical expression of RUL distribution of aero-engines based on the RCR model considering random failure threshold(RFT)is derived in a closed-form.Finally,a case study of turbofan engine is used to demonstrate the effectiveness and superiority of the RUL prediction method and the parameters estimation method of failure threshold proposed.
文摘Objective This study was to evaluate the efficacy and safety of a short acting reduced dose fibrinolytic regimen to promote early infarct related artery (IRA) patency for acyute myocardial infarction (AMI) patients referred for percutaneous coronary intervention (PCI).Methods Following aspirin and heparin, 166 patients were randomized to a 50 mg bolus of recombinant tissue type plasminogen activator(rt PA) or to a same volume sodium chloride injection followed by immediate primary PCI. The end points included patency rates on catheterization laboratory (cath lab) arrival, revascularization results when PCI was performed, complication rates, left ventricular function and restored patency rate following PCI. Results Patency on cath lab arrival was 64% with rt PA (34% TIMI 3,30% TIMI 2), while 31% of placebo (13% TIMI 3, 18% TIMI 2). There was no difference in the restored TIMI 3 rates of IRA between the two groups (85% vs 87%). No difference were observed in stroke or major bleeding. Left ventricular function was similar in both groups (52±9% vs 50±8%), but left ventricular ejection fraction fraction (LVEF) was higher with patent IRA (TIMI 3) on cath lab arrival than that of others (56±12% vs 48±10%).Conclusions Strategy thrombolytic regimens were compatible with subsequent PCI lead to more frequenc early recanalization (before cath lab arrival), which facilitates greater left ventricular function preservation with no augmentation of adverse events.
文摘In this research combustion of aluminum dust particles in a quiescent medium with spatially discrete sources distributed in a random way was studied by a numerical approach.A new thermal model was generated to estimate flame propagation speed in a lean/rich reaction medium.Flame speed for different particle diameters and the effects of various oxidizers such as carbon dioxide and oxygen on flame speed were studied.Nitrogen was considered the inert gas.In addition,the quenching distance and the minimum ignition energy(MIE) were studied as a function of dust concentration.Different burning time models for aluminum were employed and their results were compared with each other.The model was based on conduction heat transfer mechanism using the heat point source method.The combustion of single-particle was first studied and the solution was presented.Then the dust combustion was investigated using the superposition principle to include the effects of surrounding particles.It is found that larger particles have higher values of quenching distance in comparison with smaller particles in an assumed dust concentration.With the increase of dust concentration the value of MIE would be decreased for an assumed particle diameter.Considering random discrete heat sources method,the obtained results of random distribution of fuel particles in space provide closer and realistic predictions of the combustion physics of aluminum dust flame as compared with the experimental findings.
