Multipass plain strain compression test of 7055 alloy was carried out on Gleeble 1500D thermomechanical simulator to study the effect of interval time on static softening behavior between two passes. Microstructural f...Multipass plain strain compression test of 7055 alloy was carried out on Gleeble 1500D thermomechanical simulator to study the effect of interval time on static softening behavior between two passes. Microstructural features of the alloy deformed with delay times varying from 0 to 180 s after achieving a reduction of ,-~52 % in the 13 stages was investigated through TEM and EBSD observations. The 14th pass of peak stresses after different delay times were gained. The peak stress decreases with the interstage delay time increasing, but the decreasing trend is gradually slower. Static recovery, metadynamic recrystallization, and/or static recrystallization can be found in the alloy during two passes. The recovery and recrystallization degree increases with longer interstage delay time. The static recovery is the main softening mechanism. Subgrain coalescence and subgrain growth together with particle-stimulated nucleation are the main nucleation mechanisms for static recrystallization.展开更多
Amyotrophic lateral sclerosis is a rare neurodegenerative disease characterized by the involvement of both upper and lower motor neurons.Early bilateral limb involvement significantly affects patients'daily lives ...Amyotrophic lateral sclerosis is a rare neurodegenerative disease characterized by the involvement of both upper and lower motor neurons.Early bilateral limb involvement significantly affects patients'daily lives and may lead them to be confined to bed.However,the effect of upper and lower motor neuron impairment and other risk factors on bilateral limb involvement is unclear.To address this issue,we retrospectively collected data from 586 amyotrophic lateral sclerosis patients with limb onset diagnosed at Peking University Third Hospital between January 2020 and May 2022.A univariate analysis revealed no significant differences in the time intervals of spread in different directions between individuals with upper motor neuron-dominant amyotrophic lateral sclerosis and those with classic amyotrophic lateral sclerosis.We used causal directed acyclic graphs for risk factor determination and Cox proportional hazards models to investigate the association between the duration of bilateral limb involvement and clinical baseline characteristics in amyotrophic lateral sclerosis patients.Multiple factor analyses revealed that higher upper motor neuron scores(hazard ratio[HR]=1.05,95%confidence interval[CI]=1.01–1.09,P=0.018),onset in the left limb(HR=0.72,95%CI=0.58–0.89,P=0.002),and a horizontal pattern of progression(HR=0.46,95%CI=0.37–0.58,P<0.001)were risk factors for a shorter interval until bilateral limb involvement.The results demonstrated that a greater degree of upper motor neuron involvement might cause contralateral limb involvement to progress more quickly in limb-onset amyotrophic lateral sclerosis patients.These findings may improve the management of amyotrophic lateral sclerosis patients with limb onset and the prediction of patient prognosis.展开更多
Objective： To study the influences of different time intervals between loop electrosurgical excision （LEEP） and abdominal hysterectomy or radical hysterectomy on postoperative complications. Methods： Sixty-eight p...Objective： To study the influences of different time intervals between loop electrosurgical excision （LEEP） and abdominal hysterectomy or radical hysterectomy on postoperative complications. Methods： Sixty-eight patients, who received subsequent abdominal hysterectomy or radical hysterectomy after LEEP due to C1N III and cervical cancer （IA1, IA2 and IB1）, were included in the present study. The hospital and clinic records of these patients were reviewed. The patients were divided into three groups according to the time intervals between LEEP and hysterectomy or radical hysterectomy： group l（within 48 h）, group 2 （between 48 h to 6 weeks）, and group 3（〉 6 weeks ）.Results： General characteristics of patients, including the mean age, delivery history, BMI, menopausal status, clinical stage and HPV infection, were comparable between patients of different groups. There were no significant differences in the mean transfusion amount, posthysterectomy hospital stay or operation time between different groups. The frequencies and spectrum of complications were not significantly affected by the time interval between LEEP and hysterectomy or radical hysterectomy. Conclusion： It is concluded that whenever the LEEP is done, the operation including hysterectomy or radical hysterectomy can be conducted at any time as it is necessary for the patients.展开更多
AIM:To identify the association of the vitreoretinal surgeons'experience with the time interval between parsplana vitrectomy(PPV)and cataract extraction(CE).METHODS:Eyes with prior PPV and following CE were includ...AIM:To identify the association of the vitreoretinal surgeons'experience with the time interval between parsplana vitrectomy(PPV)and cataract extraction(CE).METHODS:Eyes with prior PPV and following CE were included in this retrospective cohort study.The years of practice and the annual case volume were used to describe the surgeons'experience.Multivariable linear regression analysis was used to investigate the relationship between surgeons'experience and the time interval adjusted for the patients age,gender,intraocular tamponade,and case complexity.RESULTS:Of 132430 eyes,1445 eyes were included in this study.In multivariable linear regression analysis,cases performed by surgeons with>20 practice years had longer time intervals compared with surgeons with<10 practice years after adjusted for other variables(β=0.329,95%CI:0.113 to 0.549,P=0.003).No difference in time interval was detected for comparing the lowest with the highest volume groups(β=0.089,95%CI:-0.164 to 0.343,P=0.343).The surgeons'practice years were not directly with the volume.For complicated surgery,the higherpractice-year surgeons had longer time interval than lowerpractice-year surgeons.CONCLUSION:The time intervals from PPV to CE is longer in higher-practice-year surgeons.The surgeons'practice years may have a greater effect on the time interval than annual case volume in high-complexity cases.Matching the complexity of vitreoretinal diseases with the surgeons'practice year should be considered.展开更多
A conveyor belt driven by wound rotor motors produces dynamic tension, velocity and accelerationduring starting. The terrible situation (such as resonance) in dynamic analysis and design is that system naturalfrequenc...A conveyor belt driven by wound rotor motors produces dynamic tension, velocity and accelerationduring starting. The terrible situation (such as resonance) in dynamic analysis and design is that system naturalfrequencies are equal to those for switching off electric resistances. This paper analyzes and determines systemnatural frequencies based on a modeling method of receptances with the analysis of sub-systems model and of theprinciple of their addition and conveyor loop closure. It also puts forward to calculate the time interval for switching off electric resistances. The starting of one conveyor is simulated by lumped-mass-spring-model software tofurther illustrate the influence of time interval for switching off electric resistances on conveyor dynamic behavior. Two methods are also compared. The receptance model is proved to be an excellent alternative.展开更多
By computing and classifying the data of gully offset obtained from field surveys along the Tianjingshan fault zone and estimating the ages of three types of gullies,the strike-slip rates along the fault zone are disc...By computing and classifying the data of gully offset obtained from field surveys along the Tianjingshan fault zone and estimating the ages of three types of gullies,the strike-slip rates along the fault zone are discussed in different time intervals and fault segments.The results suggest that the intensity of activity along the fault zone is not strong,but the differences between different time intervals and fault segments since the late Pleistocene have been obvious.The average rates range from 0.23 mm/a to 1.62 mm/a.The largest average rate is 1.40 mm/a,which occurred in the early and middle of late Pleistocene along the western segment of the fault zone.Since the late stage of the late Pleistocene,the center of faulting activity of the fault zone has shifted to the middle segment,and the average slip rates range have changed from 1.30 mm/a to 1.63 mm/a.展开更多
The time interval of neibouring neutrons emitted from a steady state neutron source can be treated as that from a time-dependent neutron source. In the rockspace, the neutron flux is given by the neutron diffusion equ...The time interval of neibouring neutrons emitted from a steady state neutron source can be treated as that from a time-dependent neutron source. In the rockspace, the neutron flux is given by the neutron diffusion equation and is composedof an infinite number of 'modes'. Each 'mode' is composed of two die-away curves.The delay action has been discussed and used to measure the time interval withonly one detector in the experimellt. Nuclear reactions with the time distributiondue to different types of radiations observed in the neutron well-logging methods arepresented with a view to getting the rock nuclear parameters from the time intervaltechnique.展开更多
Definitions of the mechanical parameters entering the Bohr model of the hydrogen atom allowed us to calculate the time intervals connected with the electron transitions between the nearest-neighbouring energy levels i...Definitions of the mechanical parameters entering the Bohr model of the hydrogen atom allowed us to calculate the time intervals connected with the electron transitions between the nearest-neighbouring energy levels in the atom. This is done in a strictly non-probabilistic way. The time results are compared with those derived earlier on the basis of the classical Joule-Lenz law for the energy emission adapted to the case of the electron transfer in the quantum systems. A similar formalism has been next applied to the harmonic oscillator and a particle moving in the one-dimensional potential box.展开更多
The problem of variable sampling time interval which appears in application of Kalman Filtering is analyzed and the corresponding filtering process with or without present transition matrix is suggested, then an appli...The problem of variable sampling time interval which appears in application of Kalman Filtering is analyzed and the corresponding filtering process with or without present transition matrix is suggested, then an application experiment for astronomical surveying is introduced. In this process, the known stochastically variable sampling time intervals play the roles as deterministic input sequences of the state-space description, and the corresponding matrix and (if needed) state transition matrix can be established by performing real-time and structure-linear system identification.展开更多
The modern TSs （total stations） have reached a very high level in the provided reading and reliability （accuracy and precision） of their measurements. The evolution of the digital technology has helped in this dir...The modern TSs （total stations） have reached a very high level in the provided reading and reliability （accuracy and precision） of their measurements. The evolution of the digital technology has helped in this direction. Thus, the TSs can support all requirements for the stake out and monitoring of modern survey engineering and constructions projects. Their complicated manufacturing process and the sensitivity of their components require gauging, adjusting and calibration at certain time intervals. This appears to be the only way in order to assure the precision of measurements provided by the manufacturer and the reliability of the works they are used for. The goal of this paper is to propose a method for the estimation of the gauging time interval for modern YSs. which could be used by any user. More specifically, the indispensable need for the TSs gauging is elevated and documented. All the parameters that influence their operation are registered. A model expressed by a scale of grades is defined, leading thus to an equation for the calculation of the time interval for the next needed gauging and calibration.展开更多
This study utilizes a time-precedence network technique to construct two models of multi-mode resource constrained project scheduling problem with discounted cash flows （MRCPSPDCF）, individually including the progre...This study utilizes a time-precedence network technique to construct two models of multi-mode resource constrained project scheduling problem with discounted cash flows （MRCPSPDCF）, individually including the progress payment （PP） and the payment at an equal time interval （ETI）. The objective of each model is to maximize the net present value （NPV） for all cash flows in the project, subject to the related operational constraints. The models are characterized as NP-hard. A heuristic algorithm, coupled with two upper bound solutions, is proposed to efficiently solve the models and evaluate the heuristic algorithm performance which was not performed in past studies. The results show that the performance of proposed models and heuristic algorithm is good.展开更多
BACKGROUND Epidemiologically,in China,locally advanced rectal cancer is a more common form of rectal cancer.Preoperative neoadjuvant concurrent chemoradiotherapy can effectively reduce the size of locally invasive tum...BACKGROUND Epidemiologically,in China,locally advanced rectal cancer is a more common form of rectal cancer.Preoperative neoadjuvant concurrent chemoradiotherapy can effectively reduce the size of locally invasive tumors and improve disease-free survival(DFS)and pathologic response after surgery.At present,this modality has become the standard protocol for the treatment of locally advanced rectal cancer in many centers,but the optimal time for surgery after neoadjuvant therapy is still controversial.AIM To investigate the impact of time interval between neoadjuvant therapy and surgery on DFS and pathologic response in patients with locally advanced rectal cancer.METHODS A total of 231 patients who were classified as having clinical stage II or III advanced rectal cancer and underwent neoadjuvant chemoradiation followed by surgery at the National Cancer Center/Cancer Hospital,Chinese Academy of Medical Sciences and Peking Union Medical College from November 2014 to August 2017 were involved in this retrospective cohort study.The patients were divided into two groups based on the different time intervals between neoadjuvant therapy and surgery:139(60.2%)patients were in group A(≤9 wk),and 92(39.2%)patients were in group B(>9 wk).DFS and pathologic response were analyzed as the primary endpoints.The secondary endpoints were postoperative complications and sphincter preservation.RESULTS For the 231 patients included,surgery was performed at≤9 wk in 139(60.2%)patients and at>9 wk in 92(39.8%).The patients’clinical characteristics,surgical results,and tumor outcomes were analyzed through univariate analysis combined with multivariate regression analysis.The overall pathologic complete response(pCR)rate was 27.2%(n=25)in the longer time interval group(>9 wk)and 10.8%(n=15)in the shorter time interval group(≤9 wk,P=0.001).The postoperative complications did not differ between the groups(group A,5%vs group B,5.4%;P=0.894).Surgical procedures for sphincter preservation were performed in 113(48.9%)patients,which were not significantly different between the groups(group A,52.5%vs group B,43.5%;P=0.179).The pCR rate was an independent factor affected by time interval(P=0.009;odds ratio[OR]=2.668;95%CI:1.276-5.578).Kaplan-Meier analysis and Cox regression analysis showed that the longer time interval(>9 wk)was a significant independent prognostic factor for DFS(P=0.032;OR=2.295;95%CI:1.074-4.905),but the time interval was not an independent prognostic factor for overall survival(P>0.05).CONCLUSION A longer time interval to surgery after neoadjuvant therapy may improve the pCR rate and DFS but has little impact on postoperative complications and sphincter preservation.展开更多
Growing evidence indicates that extreme heat and rain may occur in succession within short time periods and cause greater impacts than individual events separated in time and space.Therefore,many studies have examined...Growing evidence indicates that extreme heat and rain may occur in succession within short time periods and cause greater impacts than individual events separated in time and space.Therefore,many studies have examined the impacts of compound hazard events on the social-ecological system at various scales.The definition of compound events is fundamental for such research.However,there are no existing studies that support the determination of time interval between individual events of a compound rainstorm and heatwave(CRH)event,which consists of two or more potentially qualifying component heatwave and rainstorm events.To address the deficiency in defining what individual events can constitute a CRH event,this study proposed a novel method to determine the maximum time interval for CRH events through the change in CRH event frequency with increasing time interval between individual events,using southern China as a case study.The results show that the threshold identified by the proposed method is reasonable.For more than 90%of the meteorological stations,the frequency of CRH events has reached a maximum when the time interval is less than or equal to the threshold.This study can aid in time interval selection,which is an important step for subsequent study of CRH events.展开更多
The popularity of mobile devices with sensors is captivating the attention of researchers to modern techniques,such as the internet of things(IoT)and mobile crowdsensing(MCS).The core concept behind MCS is to use the ...The popularity of mobile devices with sensors is captivating the attention of researchers to modern techniques,such as the internet of things(IoT)and mobile crowdsensing(MCS).The core concept behind MCS is to use the power of mobile sensors to accomplish a difficult task collaboratively,with each mobile user completing much simpler micro-tasks.This paper discusses the task assignment problem in mobile crowdsensing,which is dependent on sensing time and path planning with the constraints of participant travel distance budgets and sensing time intervals.The goal is to minimize aggregate sensing time for mobile users,which reduces energy consumption to encourage more participants to engage in sensing activities and maximize total task quality.This paper introduces a two-phase task assignment framework called location time-based algorithm(LTBA).LTBA is a framework that enhances task assignment in MCS,whereas assigning tasks requires overlapping time intervals between tasks and mobile users’tasks and the location of tasks and mobile users’paths.The process of assigning the nearest task to the mobile user’s current path depends on the ant colony optimization algorithm(ACO)and Euclidean distance.LTBA combines two algorithms:(1)greedy online allocation algorithm and(2)bio-inspired traveldistance-balance-based algorithm(B-DBA).The greedy algorithm was sensing time interval-based and worked on reducing the overall sensing time of the mobile user.B-DBA was location-based and worked on maximizing total task quality.The results demonstrate that the average task quality is 0.8158,0.7093,and 0.7733 for LTBA,B-DBA,and greedy,respectively.The sensing time was reduced to 644,1782,and 685 time units for LTBA,B-DBA,and greedy,respectively.Combining the algorithms improves task assignment in MCS for both total task quality and sensing time.The results demonstrate that combining the two algorithms in LTBA is the best performance for total task quality and total sensing time,and the greedy algorithm follows it then B-DBA.展开更多
The aim of the paper is to get an insight into the time interval of electron emission done between two neighbouring energy levels of the hydrogen atom. To this purpose, in the first step, the formulae of the special r...The aim of the paper is to get an insight into the time interval of electron emission done between two neighbouring energy levels of the hydrogen atom. To this purpose, in the first step, the formulae of the special relativity are applied to demonstrate the conditions which can annihilate the electrostatic force acting between the nucleus and electron in the atom. This result is obtained when a suitable electron speed entering the Lorentz transformation is combined with the strength of the magnetic field acting normally to the electron orbit in the atom. In the next step, the Maxwell equation characterizing the electromotive force is applied to calculate the time interval connected with the change of the magnetic field necessary to produce the force. It is shown that the time interval obtained from the Maxwell equation, multiplied by the energy change of two neighbouring energy levels considered in the atom, does satisfy the Joule-Lenz formula associated with the quantum electron energy emission rate between the levels.展开更多
A relation between the intervals of energy and time, derived in a former paper and associated with the electron transitions on the Fermi surface of a metal, is examined in comparison with the experimental data. These ...A relation between the intervals of energy and time, derived in a former paper and associated with the electron transitions on the Fermi surface of a metal, is examined in comparison with the experimental data. These data are obtained from the de-excitation process of electrons in metals. A comparison between theory and experiment demonstrated that the new relation between energy and time is fitted much better for the experimental results than the well-known relation due to the Heisenberg theory.展开更多
The energy emitted by an electron in course of its transition between two quantum levels can be considered as a dissipated energy. This energy is obtained within a definite interval of time. The problem of the size of...The energy emitted by an electron in course of its transition between two quantum levels can be considered as a dissipated energy. This energy is obtained within a definite interval of time. The problem of the size of the time interval necessary for transitions is examined both on the ground of the quantum approach as well as classical electrodynamics. It is found that in fact the emission time approaches the time interval connected with acceleration of a classical velocity of the electron particle from one of its quantum levels to a neighbouring one.展开更多
We introduce a concept of episode referring to a time interval in the development of a dynamic phenomenon that is characterized by multiple time-variant attributes.A data structure representing a single episode is a m...We introduce a concept of episode referring to a time interval in the development of a dynamic phenomenon that is characterized by multiple time-variant attributes.A data structure representing a single episode is a multivariate time series.To analyse collections of episodes,we propose an approach that is based on recognition of particular patterns in the temporal variation of the variables within episodes.Each episode is thus represented by a combination of patterns.Using this representation,we apply visual analytics techniques to fulfil a set of analysis tasks,such as investigation of the temporal distribution of the patterns,frequencies of transitions between the patterns in episode sequences,and co-occurrences of patterns of different variables within same episodes.We demonstrate our approach on two examples using real-world data,namely,dynamics of human mobility indicators during the COVID-19 pandemic and characteristics of football team movements during episodes of ball turnover.展开更多
Mapping soil organic matter(SOM)content has become an important application of digital soil mapping.In this study,we processed all Sentinel-2 images covering the bare-soil period(March to June)in Northeast China from ...Mapping soil organic matter(SOM)content has become an important application of digital soil mapping.In this study,we processed all Sentinel-2 images covering the bare-soil period(March to June)in Northeast China from 2019 to 2022 and integrated the observation results into synthetic materials with four defined time intervals(10,15,20,and 30 d).Then,we used synthetic images corresponding to different time periods to conduct SOM mapping and determine the optimal time interval and time period beforefinally assessing the impacts of adding environmental covariates.The results showed the following:(1)in SOM mapping,the highest accuracy was obtained using day-of-year(DOY)120 to 140 synthetic images with 20 d time intervals,as well as with different time intervals,ranked as follows:20 d>30 d>15 d>10 d;(2)when using synthetic images at different time intervals to predict SOM,the best time period for predicting SOM was always within May;and(3)adding environmental covariates effectively improved the SOM mapping performance,and the multiyear average temperature was the most important factor.In general,our results demonstrated the valuable potential of SOM mapping using multiyear synthetic imagery,thereby allowing detailed mapping of large areas of cultivated soil.展开更多
基金financially supported by the Natural Science Foundation of Inner Mongolia (No. 2011bs0802)Research Fund for the Higher Education of Inner Mongolia (No. NJZY11075)
文摘Multipass plain strain compression test of 7055 alloy was carried out on Gleeble 1500D thermomechanical simulator to study the effect of interval time on static softening behavior between two passes. Microstructural features of the alloy deformed with delay times varying from 0 to 180 s after achieving a reduction of ,-~52 % in the 13 stages was investigated through TEM and EBSD observations. The 14th pass of peak stresses after different delay times were gained. The peak stress decreases with the interstage delay time increasing, but the decreasing trend is gradually slower. Static recovery, metadynamic recrystallization, and/or static recrystallization can be found in the alloy during two passes. The recovery and recrystallization degree increases with longer interstage delay time. The static recovery is the main softening mechanism. Subgrain coalescence and subgrain growth together with particle-stimulated nucleation are the main nucleation mechanisms for static recrystallization.
基金supported by the National Natural Science Foundation of China,Nos.82071426,81873784Clinical Cohort Construction Program of Peking University Third Hospital,No.BYSYDL2019002(all to DF)。
文摘Amyotrophic lateral sclerosis is a rare neurodegenerative disease characterized by the involvement of both upper and lower motor neurons.Early bilateral limb involvement significantly affects patients'daily lives and may lead them to be confined to bed.However,the effect of upper and lower motor neuron impairment and other risk factors on bilateral limb involvement is unclear.To address this issue,we retrospectively collected data from 586 amyotrophic lateral sclerosis patients with limb onset diagnosed at Peking University Third Hospital between January 2020 and May 2022.A univariate analysis revealed no significant differences in the time intervals of spread in different directions between individuals with upper motor neuron-dominant amyotrophic lateral sclerosis and those with classic amyotrophic lateral sclerosis.We used causal directed acyclic graphs for risk factor determination and Cox proportional hazards models to investigate the association between the duration of bilateral limb involvement and clinical baseline characteristics in amyotrophic lateral sclerosis patients.Multiple factor analyses revealed that higher upper motor neuron scores(hazard ratio[HR]=1.05,95%confidence interval[CI]=1.01–1.09,P=0.018),onset in the left limb(HR=0.72,95%CI=0.58–0.89,P=0.002),and a horizontal pattern of progression(HR=0.46,95%CI=0.37–0.58,P<0.001)were risk factors for a shorter interval until bilateral limb involvement.The results demonstrated that a greater degree of upper motor neuron involvement might cause contralateral limb involvement to progress more quickly in limb-onset amyotrophic lateral sclerosis patients.These findings may improve the management of amyotrophic lateral sclerosis patients with limb onset and the prediction of patient prognosis.
文摘Objective： To study the influences of different time intervals between loop electrosurgical excision （LEEP） and abdominal hysterectomy or radical hysterectomy on postoperative complications. Methods： Sixty-eight patients, who received subsequent abdominal hysterectomy or radical hysterectomy after LEEP due to C1N III and cervical cancer （IA1, IA2 and IB1）, were included in the present study. The hospital and clinic records of these patients were reviewed. The patients were divided into three groups according to the time intervals between LEEP and hysterectomy or radical hysterectomy： group l（within 48 h）, group 2 （between 48 h to 6 weeks）, and group 3（〉 6 weeks ）.Results： General characteristics of patients, including the mean age, delivery history, BMI, menopausal status, clinical stage and HPV infection, were comparable between patients of different groups. There were no significant differences in the mean transfusion amount, posthysterectomy hospital stay or operation time between different groups. The frequencies and spectrum of complications were not significantly affected by the time interval between LEEP and hysterectomy or radical hysterectomy. Conclusion： It is concluded that whenever the LEEP is done, the operation including hysterectomy or radical hysterectomy can be conducted at any time as it is necessary for the patients.
基金Supported by the National Key Research and Development Program of China(No.2017YFC1104603)the National Natural Science Foundation of China(No.81770909,No.81970783)。
文摘AIM:To identify the association of the vitreoretinal surgeons'experience with the time interval between parsplana vitrectomy(PPV)and cataract extraction(CE).METHODS:Eyes with prior PPV and following CE were included in this retrospective cohort study.The years of practice and the annual case volume were used to describe the surgeons'experience.Multivariable linear regression analysis was used to investigate the relationship between surgeons'experience and the time interval adjusted for the patients age,gender,intraocular tamponade,and case complexity.RESULTS:Of 132430 eyes,1445 eyes were included in this study.In multivariable linear regression analysis,cases performed by surgeons with>20 practice years had longer time intervals compared with surgeons with<10 practice years after adjusted for other variables(β=0.329,95%CI:0.113 to 0.549,P=0.003).No difference in time interval was detected for comparing the lowest with the highest volume groups(β=0.089,95%CI:-0.164 to 0.343,P=0.343).The surgeons'practice years were not directly with the volume.For complicated surgery,the higherpractice-year surgeons had longer time interval than lowerpractice-year surgeons.CONCLUSION:The time intervals from PPV to CE is longer in higher-practice-year surgeons.The surgeons'practice years may have a greater effect on the time interval than annual case volume in high-complexity cases.Matching the complexity of vitreoretinal diseases with the surgeons'practice year should be considered.
文摘A conveyor belt driven by wound rotor motors produces dynamic tension, velocity and accelerationduring starting. The terrible situation (such as resonance) in dynamic analysis and design is that system naturalfrequencies are equal to those for switching off electric resistances. This paper analyzes and determines systemnatural frequencies based on a modeling method of receptances with the analysis of sub-systems model and of theprinciple of their addition and conveyor loop closure. It also puts forward to calculate the time interval for switching off electric resistances. The starting of one conveyor is simulated by lumped-mass-spring-model software tofurther illustrate the influence of time interval for switching off electric resistances on conveyor dynamic behavior. Two methods are also compared. The receptance model is proved to be an excellent alternative.
基金This project was sponsored by the State Seismological Bureau (85-02-3-3), China
文摘By computing and classifying the data of gully offset obtained from field surveys along the Tianjingshan fault zone and estimating the ages of three types of gullies,the strike-slip rates along the fault zone are discussed in different time intervals and fault segments.The results suggest that the intensity of activity along the fault zone is not strong,but the differences between different time intervals and fault segments since the late Pleistocene have been obvious.The average rates range from 0.23 mm/a to 1.62 mm/a.The largest average rate is 1.40 mm/a,which occurred in the early and middle of late Pleistocene along the western segment of the fault zone.Since the late stage of the late Pleistocene,the center of faulting activity of the fault zone has shifted to the middle segment,and the average slip rates range have changed from 1.30 mm/a to 1.63 mm/a.
文摘The time interval of neibouring neutrons emitted from a steady state neutron source can be treated as that from a time-dependent neutron source. In the rockspace, the neutron flux is given by the neutron diffusion equation and is composedof an infinite number of 'modes'. Each 'mode' is composed of two die-away curves.The delay action has been discussed and used to measure the time interval withonly one detector in the experimellt. Nuclear reactions with the time distributiondue to different types of radiations observed in the neutron well-logging methods arepresented with a view to getting the rock nuclear parameters from the time intervaltechnique.
文摘Definitions of the mechanical parameters entering the Bohr model of the hydrogen atom allowed us to calculate the time intervals connected with the electron transitions between the nearest-neighbouring energy levels in the atom. This is done in a strictly non-probabilistic way. The time results are compared with those derived earlier on the basis of the classical Joule-Lenz law for the energy emission adapted to the case of the electron transfer in the quantum systems. A similar formalism has been next applied to the harmonic oscillator and a particle moving in the one-dimensional potential box.
文摘The problem of variable sampling time interval which appears in application of Kalman Filtering is analyzed and the corresponding filtering process with or without present transition matrix is suggested, then an application experiment for astronomical surveying is introduced. In this process, the known stochastically variable sampling time intervals play the roles as deterministic input sequences of the state-space description, and the corresponding matrix and (if needed) state transition matrix can be established by performing real-time and structure-linear system identification.
文摘The modern TSs （total stations） have reached a very high level in the provided reading and reliability （accuracy and precision） of their measurements. The evolution of the digital technology has helped in this direction. Thus, the TSs can support all requirements for the stake out and monitoring of modern survey engineering and constructions projects. Their complicated manufacturing process and the sensitivity of their components require gauging, adjusting and calibration at certain time intervals. This appears to be the only way in order to assure the precision of measurements provided by the manufacturer and the reliability of the works they are used for. The goal of this paper is to propose a method for the estimation of the gauging time interval for modern YSs. which could be used by any user. More specifically, the indispensable need for the TSs gauging is elevated and documented. All the parameters that influence their operation are registered. A model expressed by a scale of grades is defined, leading thus to an equation for the calculation of the time interval for the next needed gauging and calibration.
文摘This study utilizes a time-precedence network technique to construct two models of multi-mode resource constrained project scheduling problem with discounted cash flows （MRCPSPDCF）, individually including the progress payment （PP） and the payment at an equal time interval （ETI）. The objective of each model is to maximize the net present value （NPV） for all cash flows in the project, subject to the related operational constraints. The models are characterized as NP-hard. A heuristic algorithm, coupled with two upper bound solutions, is proposed to efficiently solve the models and evaluate the heuristic algorithm performance which was not performed in past studies. The results show that the performance of proposed models and heuristic algorithm is good.
基金Supported by the National Key Research and Development Plan"Research on Prevention and Control of Major Chronic Non-Communicable Diseases",No.2019YFC1315705the Medicine and Health Technology Innovation Project of Chinese Academy of Medical Sciences,No.2017-12M-1-006.
文摘BACKGROUND Epidemiologically,in China,locally advanced rectal cancer is a more common form of rectal cancer.Preoperative neoadjuvant concurrent chemoradiotherapy can effectively reduce the size of locally invasive tumors and improve disease-free survival(DFS)and pathologic response after surgery.At present,this modality has become the standard protocol for the treatment of locally advanced rectal cancer in many centers,but the optimal time for surgery after neoadjuvant therapy is still controversial.AIM To investigate the impact of time interval between neoadjuvant therapy and surgery on DFS and pathologic response in patients with locally advanced rectal cancer.METHODS A total of 231 patients who were classified as having clinical stage II or III advanced rectal cancer and underwent neoadjuvant chemoradiation followed by surgery at the National Cancer Center/Cancer Hospital,Chinese Academy of Medical Sciences and Peking Union Medical College from November 2014 to August 2017 were involved in this retrospective cohort study.The patients were divided into two groups based on the different time intervals between neoadjuvant therapy and surgery:139(60.2%)patients were in group A(≤9 wk),and 92(39.2%)patients were in group B(>9 wk).DFS and pathologic response were analyzed as the primary endpoints.The secondary endpoints were postoperative complications and sphincter preservation.RESULTS For the 231 patients included,surgery was performed at≤9 wk in 139(60.2%)patients and at>9 wk in 92(39.8%).The patients’clinical characteristics,surgical results,and tumor outcomes were analyzed through univariate analysis combined with multivariate regression analysis.The overall pathologic complete response(pCR)rate was 27.2%(n=25)in the longer time interval group(>9 wk)and 10.8%(n=15)in the shorter time interval group(≤9 wk,P=0.001).The postoperative complications did not differ between the groups(group A,5%vs group B,5.4%;P=0.894).Surgical procedures for sphincter preservation were performed in 113(48.9%)patients,which were not significantly different between the groups(group A,52.5%vs group B,43.5%;P=0.179).The pCR rate was an independent factor affected by time interval(P=0.009;odds ratio[OR]=2.668;95%CI:1.276-5.578).Kaplan-Meier analysis and Cox regression analysis showed that the longer time interval(>9 wk)was a significant independent prognostic factor for DFS(P=0.032;OR=2.295;95%CI:1.074-4.905),but the time interval was not an independent prognostic factor for overall survival(P>0.05).CONCLUSION A longer time interval to surgery after neoadjuvant therapy may improve the pCR rate and DFS but has little impact on postoperative complications and sphincter preservation.
基金funded by the Joint Funds of the National Natural Science Foundation of China(Grant No.U22B2011)the Ministry of Education and State Administration of Foreign Experts Aff airs,China(Grant No.BP0820003)the Key Laboratory of Environmental Change and Natural Disaster of Ministry of Education(2023-KF-13)。
文摘Growing evidence indicates that extreme heat and rain may occur in succession within short time periods and cause greater impacts than individual events separated in time and space.Therefore,many studies have examined the impacts of compound hazard events on the social-ecological system at various scales.The definition of compound events is fundamental for such research.However,there are no existing studies that support the determination of time interval between individual events of a compound rainstorm and heatwave(CRH)event,which consists of two or more potentially qualifying component heatwave and rainstorm events.To address the deficiency in defining what individual events can constitute a CRH event,this study proposed a novel method to determine the maximum time interval for CRH events through the change in CRH event frequency with increasing time interval between individual events,using southern China as a case study.The results show that the threshold identified by the proposed method is reasonable.For more than 90%of the meteorological stations,the frequency of CRH events has reached a maximum when the time interval is less than or equal to the threshold.This study can aid in time interval selection,which is an important step for subsequent study of CRH events.
文摘The popularity of mobile devices with sensors is captivating the attention of researchers to modern techniques,such as the internet of things(IoT)and mobile crowdsensing(MCS).The core concept behind MCS is to use the power of mobile sensors to accomplish a difficult task collaboratively,with each mobile user completing much simpler micro-tasks.This paper discusses the task assignment problem in mobile crowdsensing,which is dependent on sensing time and path planning with the constraints of participant travel distance budgets and sensing time intervals.The goal is to minimize aggregate sensing time for mobile users,which reduces energy consumption to encourage more participants to engage in sensing activities and maximize total task quality.This paper introduces a two-phase task assignment framework called location time-based algorithm(LTBA).LTBA is a framework that enhances task assignment in MCS,whereas assigning tasks requires overlapping time intervals between tasks and mobile users’tasks and the location of tasks and mobile users’paths.The process of assigning the nearest task to the mobile user’s current path depends on the ant colony optimization algorithm(ACO)and Euclidean distance.LTBA combines two algorithms:(1)greedy online allocation algorithm and(2)bio-inspired traveldistance-balance-based algorithm(B-DBA).The greedy algorithm was sensing time interval-based and worked on reducing the overall sensing time of the mobile user.B-DBA was location-based and worked on maximizing total task quality.The results demonstrate that the average task quality is 0.8158,0.7093,and 0.7733 for LTBA,B-DBA,and greedy,respectively.The sensing time was reduced to 644,1782,and 685 time units for LTBA,B-DBA,and greedy,respectively.Combining the algorithms improves task assignment in MCS for both total task quality and sensing time.The results demonstrate that combining the two algorithms in LTBA is the best performance for total task quality and total sensing time,and the greedy algorithm follows it then B-DBA.
文摘The aim of the paper is to get an insight into the time interval of electron emission done between two neighbouring energy levels of the hydrogen atom. To this purpose, in the first step, the formulae of the special relativity are applied to demonstrate the conditions which can annihilate the electrostatic force acting between the nucleus and electron in the atom. This result is obtained when a suitable electron speed entering the Lorentz transformation is combined with the strength of the magnetic field acting normally to the electron orbit in the atom. In the next step, the Maxwell equation characterizing the electromotive force is applied to calculate the time interval connected with the change of the magnetic field necessary to produce the force. It is shown that the time interval obtained from the Maxwell equation, multiplied by the energy change of two neighbouring energy levels considered in the atom, does satisfy the Joule-Lenz formula associated with the quantum electron energy emission rate between the levels.
文摘A relation between the intervals of energy and time, derived in a former paper and associated with the electron transitions on the Fermi surface of a metal, is examined in comparison with the experimental data. These data are obtained from the de-excitation process of electrons in metals. A comparison between theory and experiment demonstrated that the new relation between energy and time is fitted much better for the experimental results than the well-known relation due to the Heisenberg theory.
文摘The energy emitted by an electron in course of its transition between two quantum levels can be considered as a dissipated energy. This energy is obtained within a definite interval of time. The problem of the size of the time interval necessary for transitions is examined both on the ground of the quantum approach as well as classical electrodynamics. It is found that in fact the emission time approaches the time interval connected with acceleration of a classical velocity of the electron particle from one of its quantum levels to a neighbouring one.
基金supported by Federal Ministry of Education and Research of Germany and the state of North-Rhine Westphalia as part of the Lamarr Institute for Machine Learning and Artificial Intelligence(Lamarr22B)EU in projects SoBigData++and CrexData,and by DFG within priority research program SPP VGI(project EVA-VGI).
文摘We introduce a concept of episode referring to a time interval in the development of a dynamic phenomenon that is characterized by multiple time-variant attributes.A data structure representing a single episode is a multivariate time series.To analyse collections of episodes,we propose an approach that is based on recognition of particular patterns in the temporal variation of the variables within episodes.Each episode is thus represented by a combination of patterns.Using this representation,we apply visual analytics techniques to fulfil a set of analysis tasks,such as investigation of the temporal distribution of the patterns,frequencies of transitions between the patterns in episode sequences,and co-occurrences of patterns of different variables within same episodes.We demonstrate our approach on two examples using real-world data,namely,dynamics of human mobility indicators during the COVID-19 pandemic and characteristics of football team movements during episodes of ball turnover.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(XDA28100000)the K.C.Wong Education Foundation,Jilin Provincial Development and Reform Commission Innovation Capacity Building Project(grant number 2021C044-10)the Special fund project for high-tech indus-trialization of science and technology cooperation between Jilin Province and the Chinese Academy of Sciences(2021SYHZ0013).
文摘Mapping soil organic matter(SOM)content has become an important application of digital soil mapping.In this study,we processed all Sentinel-2 images covering the bare-soil period(March to June)in Northeast China from 2019 to 2022 and integrated the observation results into synthetic materials with four defined time intervals(10,15,20,and 30 d).Then,we used synthetic images corresponding to different time periods to conduct SOM mapping and determine the optimal time interval and time period beforefinally assessing the impacts of adding environmental covariates.The results showed the following:(1)in SOM mapping,the highest accuracy was obtained using day-of-year(DOY)120 to 140 synthetic images with 20 d time intervals,as well as with different time intervals,ranked as follows:20 d>30 d>15 d>10 d;(2)when using synthetic images at different time intervals to predict SOM,the best time period for predicting SOM was always within May;and(3)adding environmental covariates effectively improved the SOM mapping performance,and the multiyear average temperature was the most important factor.In general,our results demonstrated the valuable potential of SOM mapping using multiyear synthetic imagery,thereby allowing detailed mapping of large areas of cultivated soil.
