To clarify the deformation behavior of MnS inclusions in a non-quenched and tempered steel at three different positions (edge, 1/2 radius and center) in the cross-section of the billet in the course of hot rolling, is...To clarify the deformation behavior of MnS inclusions in a non-quenched and tempered steel at three different positions (edge, 1/2 radius and center) in the cross-section of the billet in the course of hot rolling, isothermal compression experiments were performed under the deformation temperature range from 1073 to 1473 K, the reduction rates from 25% to 75% and the strain rates from 0.01 to 10 s^(−1). The variations of deformability features (i.e., aspect ratios, size distributions, and morphologies) of MnS inclusions with those isothermal compression parameters were revealed. The evaluation of the probable maximum aspect ratio of MnS inclusions at the three different positions in the cross-section of the billet after hot rolling was examined using the statistical analysis of extreme values. Results showed that the number densities of MnS inclusions at three different positions (edge, 1/2 radius and center) in the cross-section of the steel billet only fluctuated slightly when the deformation parameters varied in the isothermal compression, while the average inclusion aspect ratios in all cases generally have a negative correlation with the deformation temperature and positive correlations with the reduction ratio and the strain rate. Statistical analysis reveals that larger inclusions deform more easily during hot rolling. The effect of rolling temperature on the extreme value of the aspect ratio of inclusions is the smallest, while the effects of initial size, reduction ratio and strain rate are more significant.展开更多
Background: Probable benign paroxysmal positional vertigo, spontaneously resolved (pBPPVsr), is a variant of benign paroxysmal positional vertigo (BPPV) in which there is no observable nystagmus and no vertigo with an...Background: Probable benign paroxysmal positional vertigo, spontaneously resolved (pBPPVsr), is a variant of benign paroxysmal positional vertigo (BPPV) in which there is no observable nystagmus and no vertigo with any positional maneuver. Objectives: To calculate the incidence pBPPVsr, compare the characteristics of the patients with pBPPVsr and BPPV not spontaneously resolved and describe the spontaneous resolution in the natural course of BPPV. Methods: Multicenter prospective descriptive study. During a one-year period, all patients with suspected BPPV that presented to the Neurotology Units of five participating centers were recruited. The incidence of pBPPVsr was calculated as a percentage of the total number of patients with BPPV. The prevalence of several variables was compared between pBPPVsr and BPPV not spontaneously resolved. The timing of spontaneous resolution was estimated using Kaplan-Meier curves. Results: 457 patients met the inclusion criteria. The incidence of pBPPVsr was 33.5%. It was significantly higher in males, in patients with normal bone mass and in patients who were not taking sulpiride. A rate of 18% of spontaneous resolution after the first month and 51% after the first year was found. This percentage did not change in a significant way after this moment. The curves for males, patients under 50 and patients with normal blood pressure decreased significantly faster. Conclusions: In our serie, BPPV spontaneously resolved in half of the patients with BPPV during the first year. This seemed to occur more commonly in males and could have been hindered by sulpiride intake, osteoporosis, advanced age and high blood pressure.展开更多
Objective:Saccades accompanied by normal gain in video head impulse tests(vHIT)are often observed in patients with vestibular migraine(VM).However,they are not considered as an independent indicator,reducing their uti...Objective:Saccades accompanied by normal gain in video head impulse tests(vHIT)are often observed in patients with vestibular migraine(VM).However,they are not considered as an independent indicator,reducing their utility in diagnosing VM.To better understand clinical features of VM,it is necessary to understand raw saccades data.Methods:Fourteen patients with confirmed VM,45 patients with probable VM(p-VM)and 14 agematched healthy volunteers were included in this study.Clinical findings related to spontaneous nystagmus(SN),positional nystagmus(PN),head-shaking nystagmus(HSN),caloric test and vHIT were recorded.Raw saccades data were exported and numbered by their sequences,and their features analyzed.Results:VM patients showed no SN,PN or HSN,and less than half of them showed unilateral weakness(UW)on caloric test.The first saccades from lateral semicircular canal stimulation were the most predominant for both left and right sides.Neither velocity nor time parameters were significantly different when compared between the two sides.Most VM patients(86%)exhibited small saccades,around 35%of the head peak velocity,with a latency of 200e400 ms.Characteristics of saccades were similar in patients with p-VM.Only four normal subjects showed saccades,all unilateral and seemingly random.Conclusions:Small saccades involving bilateral semicircular canals with a scattered distribution pattern are common in patients with VM and p-VM.展开更多
Most probable number （MPN） and colony-forming unit （CFU） estimates of fecal indicator bacteria （FIB） concentration are common measures of water quality in aquatic environments. Thus, FIB intensively monitored in...Most probable number （MPN） and colony-forming unit （CFU） estimates of fecal indicator bacteria （FIB） concentration are common measures of water quality in aquatic environments. Thus, FIB intensively monitored in Yeongsan Watershed in an attempt to compare two different methods and to develop a statistical model to convert from CFU to MPN estimates or vice versa. As a result, the significant difference was found in the MPN and CFU estimates. The enumerated Escherichia coli concentrations in MPN are greater than those in CFU, except for the measurement in winter. Especially in fall, E. coli concentrations in MPN are one order of magnitude greater than that in CFU. Contrarily, enterococci bacteria in MPN are lower than those in CFU. However, in general, a strongly positive relationship are found between MPN and CFU estimates. Therefore, the statistical models were developed, and showed the reasonable converting FIB concentrations from CFU estimates to MPN estimates. We expect this study will provide preliminary information towards future research on whether different analysis methods may result in different water quality standard violation frequencies for the same water sample.展开更多
Based on the skewed function,the most probable temperature is defined and the spatiotemporal distributions of the frequencies and strengths of extreme temperature events in different climate states over China are inve...Based on the skewed function,the most probable temperature is defined and the spatiotemporal distributions of the frequencies and strengths of extreme temperature events in different climate states over China are investigated,where the climate states are referred to as State I,State II and State III,i.e.,the daily minimum temperature records of 1961-1990,1971-2000,and 1981-2009.The results show that in space the frequency of high temperature events in summer decreases clearly in the lower and middle reaches of the Yellow River in State I and that low temperature events decrease in northern China in State II.In the present state,the frequency of high temperature events increases significantly in most areas over China except the north east,while the frequency of low temperature events decreases mainly in north China and the regions between the Yangtze River and the Yellow River.The distributions of frequencies and strengths of extreme temperature events are consistent in space.The analysis of time evolution of extreme events shows that the occurrence of high temperature events become higher with the change in state,while that of low temperature events decreases.High temperature events are becoming stronger as well and deserve to be paid special attention.展开更多
Microbial transformations of toxic monomethylmercury(MMHg) and dissolved gaseous mercury(DGM) at the lower levels of the marine food web are not well understood, especially in oligotrophic and phosphorus-limited seas....Microbial transformations of toxic monomethylmercury(MMHg) and dissolved gaseous mercury(DGM) at the lower levels of the marine food web are not well understood, especially in oligotrophic and phosphorus-limited seas. To examine the effects of probable phosphorus limitation(~PP-limitation) on relations between mercury(Hg) fractions and microorganisms, we determined the total mercury(THg), total methylated mercury(MeHg), DGM, and microbiological and chemical parameters in the Central Adriatic Sea. Using statistical analysis, we assessed the potential microbial effects on Hg transformations and bioaccumulation. Only in the absence of ~PP-limitation conditions(^(NO–P)P-limitation) is MeHg significantly related to most chemical and microbial parameters, indicating metabolism-dependent Hg transformations.The heterotrophic activity of low nucleic acid bacteria(abundant in oligotrophic regions)seems responsible for most of Hg methylation under ^(NO–P)P-limitation. Under these conditions,DGM is strongly related to microbial fractions and chlorophyll a, indicating biological DGM production, which is probably not metabolically induced, as most of these relations are also observed underPP-limitation. MMHg biomagnification was observed through an increased bioaccumulation factor from microseston to mesozooplankton. Our results indicate that Hgtransformations and uptake might be enhanced under ^(NO–P)P-limitation conditions, emphasizing their impact on the transfer of Hg to higher trophic levels.展开更多
The phenomenon of stochastic bifurcation driven by the correlated non-Gaussian colored noise and the Gaussian white noise is investigated by the qualitative changes of steady states with the most probable phase portra...The phenomenon of stochastic bifurcation driven by the correlated non-Gaussian colored noise and the Gaussian white noise is investigated by the qualitative changes of steady states with the most probable phase portraits.To arrive at the Markovian approximation of the original non-Markovian stochastic process and derive the general approximate Fokker-Planck equation(FPE),we deal with the non-Gaussian colored noise and then adopt the unified colored noise approximation(UCNA).Subsequently,the theoretical equation concerning the most probable steady states is obtained by the maximum of the stationary probability density function(SPDF).The parameter of the uncorrelated additive noise intensity does enter the governing equation as a non-Markovian effect,which is in contrast to that of the uncorrelated Gaussian white noise case,where the parameter is absent from the governing equation,i.e.,the most probable steady states are mainly controlled by the uncorrelated multiplicative noise.Additionally,in comparison with the deterministic counterpart,some peculiar bifurcation behaviors with regard to the most probable steady states induced by the correlation time of non-Gaussian colored noise,the noise intensity,and the non-Gaussian noise deviation parameter are discussed.Moreover,the symmetry of the stochastic bifurcation diagrams is destroyed when the correlation between noises is concerned.Furthermore,the feasibility and accuracy of the analytical predictions are verified compared with those of the Monte Carlo(MC)simulations of the original system.展开更多
Estimates of PMP are needed in order to estimate the spillway design flood for dams which must be capable of safely passing the probable maximum flood (PMF). For over forty years the standard estimates of the Flood St...Estimates of PMP are needed in order to estimate the spillway design flood for dams which must be capable of safely passing the probable maximum flood (PMF). For over forty years the standard estimates of the Flood Studies Report (FSR) have almost always been used. However, since then several studies have shown that these values are too low, and new estimates for South West England and then Britain were published. This paper extends these studies to include the whole of the British Isles. The study uses 6570 station years’ data in a new method of frequency analysis that identifies part of the data which represents the long term situation. Further analyses to support the results of this approach have been produced from the in situ maximisation of 12 historic storms using World Meteorological Organisation methods. The results are broadly consistent with those obtained from frequency analysis. Values of 24 hour PMP in Britain range from 600 mm in upland areas of the Lake District, to 400 mm in parts of East Anglia. This range of values is present in Wales and parts of South West England. For Ireland the highest values are over the upland areas, such as in the Wicklow Mountains (550 mm) and SW Ireland (600 mm), while in the lowlands values around 350 mm can be expected. The question of uncertainty in estimating PMP is considered, most of which is due to the temporal and spatial shortcomings of the data. The implications for the probable maximum flood (PMF) and spillway design flood mean that widespread reassessment of dam safety should be carried out at once.展开更多
Objective To describe the specific features of the contact history of probable cases of severe acute respiratory syndrome (SARS) in Beijing. Methods Data of SARS cases notified from the Beijing Municipal Center for Di...Objective To describe the specific features of the contact history of probable cases of severe acute respiratory syndrome (SARS) in Beijing. Methods Data of SARS cases notified from the Beijing Municipal Center for Disease Control and Prevention (BCDC) and supplemented by other channels were collected. All the data were analyzed by descriptive epidemiology. Results ①The number of probable cases with contact history was significantly higher than the excluded cases. ②The proportion of probable cases with contact history descended with epidemic development, but this situation did not occur in health care workers (HCWs). ③The fatality rate of probable cases with contact history was significantly higher than the cases without contact history (OR=1.489). ④The proportion of probable cases with contact history was 85.86% among health care workers, which was significantly higher than that of non-health care workers (85.86% v.s. 56.44%, OR=4.69). Conclusions ①The susceptible persons with contact history may not get infected, and the contact history is just a sufficient condition of infecting SARS; ②There are 3 conceivable reasons for the descending trend of the proportion in probable cases with contact history; ③The contact history is one of the risk factors of the death of SARS cases; ④The risk of contacting with SARS among health care workers is approximately 5 times higher than that of non-HCWs.展开更多
The effects of stochastic perturbations and periodic excitations on the eutrophicated lake ecosystem are explored.Unlike the existing work in detecting early warning signals,this paper presents the most probable trans...The effects of stochastic perturbations and periodic excitations on the eutrophicated lake ecosystem are explored.Unlike the existing work in detecting early warning signals,this paper presents the most probable transition paths to characterize the regime shifts.The most probable transition paths are obtained by minimizing the Freidlin-Wentzell(FW)action functional and Onsager-Machlup(OM)action functional,respectively.The most probable path shows the movement trend of the lake eutrophication system under noise excitation,and describes the global transition behavior of the system.Under the excitation of Gaussian noise,the results show that the stability of the eutrophic state and the oligotrophic state has different results from two perspectives of potential well and the most probable transition paths.Under the excitation of Gaussian white noise and periodic force,we find that the transition occurs near the nearest distance between the stable periodic solution and the unstable periodic solution.展开更多
Most probable producing ability （MPPA） is the one factor used to compare the performance potential of dam based on the data of their progeny. The purpose of the research was to study the genetic ability of weaning w...Most probable producing ability （MPPA） is the one factor used to compare the performance potential of dam based on the data of their progeny. The purpose of the research was to study the genetic ability of weaning weight, yearling weight and calving interval of Bali cows. The weaning weight data of 296 cows derived from 99 dams, yearling weight data of 245 cows derived from 86 dams and cabAng interval data of 194 cows from 63 dams were used to estimate repeatability and MPPA of Bali cows in a herd for the three traits. Repeatability of three traits was estimated by analysis of intra-class correlation, and these in turn were used for calculating the estimated MPPA of cows. The results showed that the means of weaning weight of males and females were 95.56 ± 17.25 kg and 87.57 ± 18.45 kg, respectively; means of yearling weight were 143.39 ±25.78 kg and 136.90 ± 22.01 kg, respectively; and mean calving interval was 391.62±22.59 d. The estimated repeatability of weaning weight, yearling weight and calving interval were 0.006 ±0.059, 0.022 ± 0.068 and 0.115 ± 0.078, respectively. The best 10 dams in the herd based on the estimates of MPPA for weaning weight, yearling weight and calving interval were not the same for the three traits.展开更多
A nonlinear two-dimension dynamic model of storm surge (SS) and astronomical tide(AT) was used to investigate the effects of SS and AT on expected sea level rise (SLR) at principalcoastal stations in the Shanghai regi...A nonlinear two-dimension dynamic model of storm surge (SS) and astronomical tide(AT) was used to investigate the effects of SS and AT on expected sea level rise (SLR) at principalcoastal stations in the Shanghai region and to estimate numerically the probable maximum water lerel for2010 - 2050. Evidence suggests tha SLR causes reduction of SS; that its influence on SS depends on theintensity and path of a tropical cyclone and the station locality; tha the SLR’s effects on AT vary periodi-cally, with the peried being the same as tha of the AT’s: and that as the SLR increment grows, its impactincreases; below mean sea level (MSL) the effect is positive at rising tide and negative at ebb tide, andvice versa for the effect above MSL. Study of the probable maximum water level (by assuming SLR, SSalong favorable tropical cyclone’s path, its possible maximum intensity and effectivee spring AT at a rangeof set paths of Cyclones 5612, 8114, 9417) showed that the probable maximum water level is 740, 745,and 751 cm in the years 2010, 2030, and 2050, respetively, over the target region.展开更多
Possible.probable和likely都有"可能"的意思,但所表示的程度、含义及用法是不同的。一、从程度上看,它们表示的"可能性"依次possible.likely,probable。例: 1.It’possible,though not probable,that he will aece...Possible.probable和likely都有"可能"的意思,但所表示的程度、含义及用法是不同的。一、从程度上看,它们表示的"可能性"依次possible.likely,probable。例: 1.It’possible,though not probable,that he will aecept these terms.他可能接受这些条件,但希望很小。展开更多
这三个词都近于汉语的“可能的”,但它们隐含的意义和用法上是有区别的,现分别表述如下。 possible用于指根据情况可能存在、发生或可能做的任何事情,但往往含有“实际上希望很小”的意味。例如: I would say that while failure is pos...这三个词都近于汉语的“可能的”,但它们隐含的意义和用法上是有区别的,现分别表述如下。 possible用于指根据情况可能存在、发生或可能做的任何事情,但往往含有“实际上希望很小”的意味。例如: I would say that while failure is possible,everything pointstowards success,我认为一切都说明我们将获得成功,虽然失败是可能的。展开更多
The fuzzy comfortability of a wind-sensitive super-high tower crane is critical to guarantee occupant health and improve construction efficiency.Therefore,the wind-resistant fuzzy comfortability of a super-high tower ...The fuzzy comfortability of a wind-sensitive super-high tower crane is critical to guarantee occupant health and improve construction efficiency.Therefore,the wind-resistant fuzzy comfortability of a super-high tower crane in the Ma’anshan Yangtze River(MYR)Bridge site is analyzed in this paper.First,the membership function model that represents fuzzy comfortability is introduced in the probability density evolution method(PDEM).Second,based on Fechner’s law,the membership function curves are constructed according to three acceleration thresholds in ISO 2631.Then,the fuzzy comfortability for the super-high tower crane under stochastic wind loads is assessed on the basis of different cut-set levelsλ.Results show that the comfortability is over 0.9 under the required maximum operating wind velocity.The low sensitivity toλcan be observed in the reliability curves of ISOⅡandⅢmembership functions.The reliability of the ISOⅠmembership function is not sensitive toλwhenλ<0.7,whereas it becomes sensitive toλwhenλ>0.7.展开更多
In dynamic scenarios,visual simultaneous localization and mapping(SLAM)algorithms often incorrectly incorporate dynamic points during camera pose computation,leading to reduced accuracy and robustness.This paper prese...In dynamic scenarios,visual simultaneous localization and mapping(SLAM)algorithms often incorrectly incorporate dynamic points during camera pose computation,leading to reduced accuracy and robustness.This paper presents a dynamic SLAM algorithm that leverages object detection and regional dynamic probability.Firstly,a parallel thread employs the YOLOX object detectionmodel to gather 2D semantic information and compensate for missed detections.Next,an improved K-means++clustering algorithm clusters bounding box regions,adaptively determining the threshold for extracting dynamic object contours as dynamic points change.This process divides the image into low dynamic,suspicious dynamic,and high dynamic regions.In the tracking thread,the dynamic point removal module assigns dynamic probability weights to the feature points in these regions.Combined with geometric methods,it detects and removes the dynamic points.The final evaluation on the public TUM RGB-D dataset shows that the proposed dynamic SLAM algorithm surpasses most existing SLAM algorithms,providing better pose estimation accuracy and robustness in dynamic environments.展开更多
Based on a concept of asymptotic exponential arbitrage proposed by F?llmerSchachermayer, the author introduces a new formulation of asymptotic arbitrage with two main differences from the previous one: Firstly, the re...Based on a concept of asymptotic exponential arbitrage proposed by F?llmerSchachermayer, the author introduces a new formulation of asymptotic arbitrage with two main differences from the previous one: Firstly, the realising strategy does not depend on the maturity time while the previous one does, and secondly, the probable maximum loss is allowed to be small constant instead of a decreasing function of time. The main result gives a sufficient condition on stock prices for the existence of such asymptotic arbitrage.As a consequence, she gives a new proof of a conjecture of F?llmer and Schachermayer.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.52074198,52374342 and U21A20113)also supported by the Department of Science and Technology of Hubei Province(Grant No.2023AFB603 and No.2023DJC140).
文摘To clarify the deformation behavior of MnS inclusions in a non-quenched and tempered steel at three different positions (edge, 1/2 radius and center) in the cross-section of the billet in the course of hot rolling, isothermal compression experiments were performed under the deformation temperature range from 1073 to 1473 K, the reduction rates from 25% to 75% and the strain rates from 0.01 to 10 s^(−1). The variations of deformability features (i.e., aspect ratios, size distributions, and morphologies) of MnS inclusions with those isothermal compression parameters were revealed. The evaluation of the probable maximum aspect ratio of MnS inclusions at the three different positions in the cross-section of the billet after hot rolling was examined using the statistical analysis of extreme values. Results showed that the number densities of MnS inclusions at three different positions (edge, 1/2 radius and center) in the cross-section of the steel billet only fluctuated slightly when the deformation parameters varied in the isothermal compression, while the average inclusion aspect ratios in all cases generally have a negative correlation with the deformation temperature and positive correlations with the reduction ratio and the strain rate. Statistical analysis reveals that larger inclusions deform more easily during hot rolling. The effect of rolling temperature on the extreme value of the aspect ratio of inclusions is the smallest, while the effects of initial size, reduction ratio and strain rate are more significant.
文摘Background: Probable benign paroxysmal positional vertigo, spontaneously resolved (pBPPVsr), is a variant of benign paroxysmal positional vertigo (BPPV) in which there is no observable nystagmus and no vertigo with any positional maneuver. Objectives: To calculate the incidence pBPPVsr, compare the characteristics of the patients with pBPPVsr and BPPV not spontaneously resolved and describe the spontaneous resolution in the natural course of BPPV. Methods: Multicenter prospective descriptive study. During a one-year period, all patients with suspected BPPV that presented to the Neurotology Units of five participating centers were recruited. The incidence of pBPPVsr was calculated as a percentage of the total number of patients with BPPV. The prevalence of several variables was compared between pBPPVsr and BPPV not spontaneously resolved. The timing of spontaneous resolution was estimated using Kaplan-Meier curves. Results: 457 patients met the inclusion criteria. The incidence of pBPPVsr was 33.5%. It was significantly higher in males, in patients with normal bone mass and in patients who were not taking sulpiride. A rate of 18% of spontaneous resolution after the first month and 51% after the first year was found. This percentage did not change in a significant way after this moment. The curves for males, patients under 50 and patients with normal blood pressure decreased significantly faster. Conclusions: In our serie, BPPV spontaneously resolved in half of the patients with BPPV during the first year. This seemed to occur more commonly in males and could have been hindered by sulpiride intake, osteoporosis, advanced age and high blood pressure.
文摘Objective:Saccades accompanied by normal gain in video head impulse tests(vHIT)are often observed in patients with vestibular migraine(VM).However,they are not considered as an independent indicator,reducing their utility in diagnosing VM.To better understand clinical features of VM,it is necessary to understand raw saccades data.Methods:Fourteen patients with confirmed VM,45 patients with probable VM(p-VM)and 14 agematched healthy volunteers were included in this study.Clinical findings related to spontaneous nystagmus(SN),positional nystagmus(PN),head-shaking nystagmus(HSN),caloric test and vHIT were recorded.Raw saccades data were exported and numbered by their sequences,and their features analyzed.Results:VM patients showed no SN,PN or HSN,and less than half of them showed unilateral weakness(UW)on caloric test.The first saccades from lateral semicircular canal stimulation were the most predominant for both left and right sides.Neither velocity nor time parameters were significantly different when compared between the two sides.Most VM patients(86%)exhibited small saccades,around 35%of the head peak velocity,with a latency of 200e400 ms.Characteristics of saccades were similar in patients with p-VM.Only four normal subjects showed saccades,all unilateral and seemingly random.Conclusions:Small saccades involving bilateral semicircular canals with a scattered distribution pattern are common in patients with VM and p-VM.
基金supported by the Korean Ministry of Environment as "The Eco-technopia 21 Project" (No. 019-071-053)
文摘Most probable number （MPN） and colony-forming unit （CFU） estimates of fecal indicator bacteria （FIB） concentration are common measures of water quality in aquatic environments. Thus, FIB intensively monitored in Yeongsan Watershed in an attempt to compare two different methods and to develop a statistical model to convert from CFU to MPN estimates or vice versa. As a result, the significant difference was found in the MPN and CFU estimates. The enumerated Escherichia coli concentrations in MPN are greater than those in CFU, except for the measurement in winter. Especially in fall, E. coli concentrations in MPN are one order of magnitude greater than that in CFU. Contrarily, enterococci bacteria in MPN are lower than those in CFU. However, in general, a strongly positive relationship are found between MPN and CFU estimates. Therefore, the statistical models were developed, and showed the reasonable converting FIB concentrations from CFU estimates to MPN estimates. We expect this study will provide preliminary information towards future research on whether different analysis methods may result in different water quality standard violation frequencies for the same water sample.
基金Project supported by the National Natural Science Foundation of China (Grant No. 41105033)the National Basic Research Program of China (Grant No. 2012CB955901)
文摘Based on the skewed function,the most probable temperature is defined and the spatiotemporal distributions of the frequencies and strengths of extreme temperature events in different climate states over China are investigated,where the climate states are referred to as State I,State II and State III,i.e.,the daily minimum temperature records of 1961-1990,1971-2000,and 1981-2009.The results show that in space the frequency of high temperature events in summer decreases clearly in the lower and middle reaches of the Yellow River in State I and that low temperature events decrease in northern China in State II.In the present state,the frequency of high temperature events increases significantly in most areas over China except the north east,while the frequency of low temperature events decreases mainly in north China and the regions between the Yangtze River and the Yellow River.The distributions of frequencies and strengths of extreme temperature events are consistent in space.The analysis of time evolution of extreme events shows that the occurrence of high temperature events become higher with the change in state,while that of low temperature events decreases.High temperature events are becoming stronger as well and deserve to be paid special attention.
基金supported by the Slovenian Research Agency (program No.P1-0143project Nos.PR-06179,J1-8156)+1 种基金the European Commission (Nos.FP7-265113–GMOS,689443–ERA-PLANET)the Croatian Science Foundation (Nos.IP2014-09-4143–MICROGLOB,IP-2014-09-3606–MARIPLAN)
文摘Microbial transformations of toxic monomethylmercury(MMHg) and dissolved gaseous mercury(DGM) at the lower levels of the marine food web are not well understood, especially in oligotrophic and phosphorus-limited seas. To examine the effects of probable phosphorus limitation(~PP-limitation) on relations between mercury(Hg) fractions and microorganisms, we determined the total mercury(THg), total methylated mercury(MeHg), DGM, and microbiological and chemical parameters in the Central Adriatic Sea. Using statistical analysis, we assessed the potential microbial effects on Hg transformations and bioaccumulation. Only in the absence of ~PP-limitation conditions(^(NO–P)P-limitation) is MeHg significantly related to most chemical and microbial parameters, indicating metabolism-dependent Hg transformations.The heterotrophic activity of low nucleic acid bacteria(abundant in oligotrophic regions)seems responsible for most of Hg methylation under ^(NO–P)P-limitation. Under these conditions,DGM is strongly related to microbial fractions and chlorophyll a, indicating biological DGM production, which is probably not metabolically induced, as most of these relations are also observed underPP-limitation. MMHg biomagnification was observed through an increased bioaccumulation factor from microseston to mesozooplankton. Our results indicate that Hgtransformations and uptake might be enhanced under ^(NO–P)P-limitation conditions, emphasizing their impact on the transfer of Hg to higher trophic levels.
文摘The phenomenon of stochastic bifurcation driven by the correlated non-Gaussian colored noise and the Gaussian white noise is investigated by the qualitative changes of steady states with the most probable phase portraits.To arrive at the Markovian approximation of the original non-Markovian stochastic process and derive the general approximate Fokker-Planck equation(FPE),we deal with the non-Gaussian colored noise and then adopt the unified colored noise approximation(UCNA).Subsequently,the theoretical equation concerning the most probable steady states is obtained by the maximum of the stationary probability density function(SPDF).The parameter of the uncorrelated additive noise intensity does enter the governing equation as a non-Markovian effect,which is in contrast to that of the uncorrelated Gaussian white noise case,where the parameter is absent from the governing equation,i.e.,the most probable steady states are mainly controlled by the uncorrelated multiplicative noise.Additionally,in comparison with the deterministic counterpart,some peculiar bifurcation behaviors with regard to the most probable steady states induced by the correlation time of non-Gaussian colored noise,the noise intensity,and the non-Gaussian noise deviation parameter are discussed.Moreover,the symmetry of the stochastic bifurcation diagrams is destroyed when the correlation between noises is concerned.Furthermore,the feasibility and accuracy of the analytical predictions are verified compared with those of the Monte Carlo(MC)simulations of the original system.
文摘Estimates of PMP are needed in order to estimate the spillway design flood for dams which must be capable of safely passing the probable maximum flood (PMF). For over forty years the standard estimates of the Flood Studies Report (FSR) have almost always been used. However, since then several studies have shown that these values are too low, and new estimates for South West England and then Britain were published. This paper extends these studies to include the whole of the British Isles. The study uses 6570 station years’ data in a new method of frequency analysis that identifies part of the data which represents the long term situation. Further analyses to support the results of this approach have been produced from the in situ maximisation of 12 historic storms using World Meteorological Organisation methods. The results are broadly consistent with those obtained from frequency analysis. Values of 24 hour PMP in Britain range from 600 mm in upland areas of the Lake District, to 400 mm in parts of East Anglia. This range of values is present in Wales and parts of South West England. For Ireland the highest values are over the upland areas, such as in the Wicklow Mountains (550 mm) and SW Ireland (600 mm), while in the lowlands values around 350 mm can be expected. The question of uncertainty in estimating PMP is considered, most of which is due to the temporal and spatial shortcomings of the data. The implications for the probable maximum flood (PMF) and spillway design flood mean that widespread reassessment of dam safety should be carried out at once.
文摘Objective To describe the specific features of the contact history of probable cases of severe acute respiratory syndrome (SARS) in Beijing. Methods Data of SARS cases notified from the Beijing Municipal Center for Disease Control and Prevention (BCDC) and supplemented by other channels were collected. All the data were analyzed by descriptive epidemiology. Results ①The number of probable cases with contact history was significantly higher than the excluded cases. ②The proportion of probable cases with contact history descended with epidemic development, but this situation did not occur in health care workers (HCWs). ③The fatality rate of probable cases with contact history was significantly higher than the cases without contact history (OR=1.489). ④The proportion of probable cases with contact history was 85.86% among health care workers, which was significantly higher than that of non-health care workers (85.86% v.s. 56.44%, OR=4.69). Conclusions ①The susceptible persons with contact history may not get infected, and the contact history is just a sufficient condition of infecting SARS; ②There are 3 conceivable reasons for the descending trend of the proportion in probable cases with contact history; ③The contact history is one of the risk factors of the death of SARS cases; ④The risk of contacting with SARS among health care workers is approximately 5 times higher than that of non-HCWs.
基金supported by the National Natural Science Foundation of China(Grant Nos.12072261 and 11872305)。
文摘The effects of stochastic perturbations and periodic excitations on the eutrophicated lake ecosystem are explored.Unlike the existing work in detecting early warning signals,this paper presents the most probable transition paths to characterize the regime shifts.The most probable transition paths are obtained by minimizing the Freidlin-Wentzell(FW)action functional and Onsager-Machlup(OM)action functional,respectively.The most probable path shows the movement trend of the lake eutrophication system under noise excitation,and describes the global transition behavior of the system.Under the excitation of Gaussian noise,the results show that the stability of the eutrophic state and the oligotrophic state has different results from two perspectives of potential well and the most probable transition paths.Under the excitation of Gaussian white noise and periodic force,we find that the transition occurs near the nearest distance between the stable periodic solution and the unstable periodic solution.
文摘Most probable producing ability （MPPA） is the one factor used to compare the performance potential of dam based on the data of their progeny. The purpose of the research was to study the genetic ability of weaning weight, yearling weight and calving interval of Bali cows. The weaning weight data of 296 cows derived from 99 dams, yearling weight data of 245 cows derived from 86 dams and cabAng interval data of 194 cows from 63 dams were used to estimate repeatability and MPPA of Bali cows in a herd for the three traits. Repeatability of three traits was estimated by analysis of intra-class correlation, and these in turn were used for calculating the estimated MPPA of cows. The results showed that the means of weaning weight of males and females were 95.56 ± 17.25 kg and 87.57 ± 18.45 kg, respectively; means of yearling weight were 143.39 ±25.78 kg and 136.90 ± 22.01 kg, respectively; and mean calving interval was 391.62±22.59 d. The estimated repeatability of weaning weight, yearling weight and calving interval were 0.006 ±0.059, 0.022 ± 0.068 and 0.115 ± 0.078, respectively. The best 10 dams in the herd based on the estimates of MPPA for weaning weight, yearling weight and calving interval were not the same for the three traits.
文摘A nonlinear two-dimension dynamic model of storm surge (SS) and astronomical tide(AT) was used to investigate the effects of SS and AT on expected sea level rise (SLR) at principalcoastal stations in the Shanghai region and to estimate numerically the probable maximum water lerel for2010 - 2050. Evidence suggests tha SLR causes reduction of SS; that its influence on SS depends on theintensity and path of a tropical cyclone and the station locality; tha the SLR’s effects on AT vary periodi-cally, with the peried being the same as tha of the AT’s: and that as the SLR increment grows, its impactincreases; below mean sea level (MSL) the effect is positive at rising tide and negative at ebb tide, andvice versa for the effect above MSL. Study of the probable maximum water level (by assuming SLR, SSalong favorable tropical cyclone’s path, its possible maximum intensity and effectivee spring AT at a rangeof set paths of Cyclones 5612, 8114, 9417) showed that the probable maximum water level is 740, 745,and 751 cm in the years 2010, 2030, and 2050, respetively, over the target region.
文摘Possible.probable和likely都有"可能"的意思,但所表示的程度、含义及用法是不同的。一、从程度上看,它们表示的"可能性"依次possible.likely,probable。例: 1.It’possible,though not probable,that he will aecept these terms.他可能接受这些条件,但希望很小。
文摘这三个词都近于汉语的“可能的”,但它们隐含的意义和用法上是有区别的,现分别表述如下。 possible用于指根据情况可能存在、发生或可能做的任何事情,但往往含有“实际上希望很小”的意味。例如: I would say that while failure is possible,everything pointstowards success,我认为一切都说明我们将获得成功,虽然失败是可能的。
基金The National Natural Science Foundation of China(No.52108274,52208481,52338011)State Scholarship Fund of China Scholarship Council(No.202306090285).
文摘The fuzzy comfortability of a wind-sensitive super-high tower crane is critical to guarantee occupant health and improve construction efficiency.Therefore,the wind-resistant fuzzy comfortability of a super-high tower crane in the Ma’anshan Yangtze River(MYR)Bridge site is analyzed in this paper.First,the membership function model that represents fuzzy comfortability is introduced in the probability density evolution method(PDEM).Second,based on Fechner’s law,the membership function curves are constructed according to three acceleration thresholds in ISO 2631.Then,the fuzzy comfortability for the super-high tower crane under stochastic wind loads is assessed on the basis of different cut-set levelsλ.Results show that the comfortability is over 0.9 under the required maximum operating wind velocity.The low sensitivity toλcan be observed in the reliability curves of ISOⅡandⅢmembership functions.The reliability of the ISOⅠmembership function is not sensitive toλwhenλ<0.7,whereas it becomes sensitive toλwhenλ>0.7.
基金the National Natural Science Foundation of China(No.62063006)to the Guangxi Natural Science Foundation under Grant(Nos.2023GXNSFAA026025,AA24010001)+3 种基金to the Innovation Fund of Chinese Universities Industry-University-Research(ID:2023RY018)to the Special Guangxi Industry and Information Technology Department,Textile and Pharmaceutical Division(ID:2021 No.231)to the Special Research Project of Hechi University(ID:2021GCC028)to the Key Laboratory of AI and Information Processing,Education Department of Guangxi Zhuang Autonomous Region(Hechi University),No.2024GXZDSY009。
文摘In dynamic scenarios,visual simultaneous localization and mapping(SLAM)algorithms often incorrectly incorporate dynamic points during camera pose computation,leading to reduced accuracy and robustness.This paper presents a dynamic SLAM algorithm that leverages object detection and regional dynamic probability.Firstly,a parallel thread employs the YOLOX object detectionmodel to gather 2D semantic information and compensate for missed detections.Next,an improved K-means++clustering algorithm clusters bounding box regions,adaptively determining the threshold for extracting dynamic object contours as dynamic points change.This process divides the image into low dynamic,suspicious dynamic,and high dynamic regions.In the tracking thread,the dynamic point removal module assigns dynamic probability weights to the feature points in these regions.Combined with geometric methods,it detects and removes the dynamic points.The final evaluation on the public TUM RGB-D dataset shows that the proposed dynamic SLAM algorithm surpasses most existing SLAM algorithms,providing better pose estimation accuracy and robustness in dynamic environments.
文摘Based on a concept of asymptotic exponential arbitrage proposed by F?llmerSchachermayer, the author introduces a new formulation of asymptotic arbitrage with two main differences from the previous one: Firstly, the realising strategy does not depend on the maturity time while the previous one does, and secondly, the probable maximum loss is allowed to be small constant instead of a decreasing function of time. The main result gives a sufficient condition on stock prices for the existence of such asymptotic arbitrage.As a consequence, she gives a new proof of a conjecture of F?llmer and Schachermayer.
