AZ31 Mg alloy with heterogeneous bimodal grain structure(smaller grain size of 5-20µm and coarser grain size of 100-200µm)was subjected to accumulated extrusion bonding(AEB)at 250℃combined with two-stage ar...AZ31 Mg alloy with heterogeneous bimodal grain structure(smaller grain size of 5-20µm and coarser grain size of 100-200µm)was subjected to accumulated extrusion bonding(AEB)at 250℃combined with two-stage artificial cooling in this work,viz.local water cooling and artificial cooling.The microstructure developed consecutively as a result of discontinuous dynamic recrystallization(DDRX)for the AEBed samples.{10-12}tensile twinning also played an important role for the AEB with local water cooling at the initial extrusion stage in the container.Local water cooling could further reduce the DRXed grain size to~2.1µm comparing that without water cooling.And the grain growth rate was reduced by artificial cooling out of extrusion die.Under the combination of two-stage cooling,the fine DRXed grains at sizing band were almost retained with average grain size of~2.3µm after the sheet out of extrusion die,and the unDRXed grains with high residual dislocation density accumulation were also reserved.The tensile tests results indicated that a good strength-ductility balance with a high ultimate tensile strength(319 MPa vs.412 MPa)and fracture elongation(19.9%vs.30.3%)were obtained.The strength enhancement was mainly owing to the grain refinement and local residual plastic strain reserved by the artificial cooling.The excellent ductility originated from fine DRXed microstructure and ED-tilt double peak texture.展开更多
It is of utmost necessity to understand the dynamics of regional active accumulated temperature(AAT)to cope with the negative impacts of global warming on agroforestry development and food security and to provide a re...It is of utmost necessity to understand the dynamics of regional active accumulated temperature(AAT)to cope with the negative impacts of global warming on agroforestry development and food security and to provide a real-time and effective reference basis for regional agroforestry planning.The daily temperature data from 30 meteorological stations in Sichuan Province from 1970 to 2020,and sea surface temperature(SST)index data from the Atlantic Multiphase Oscillation(AMO)and Pacific Decadal Oscillation(PDO)were used for the study.Sichuan Province was divided into the western region(WS)and the eastern region(ES),considering 1000 m above sea level as the boundary.The spatiotemporal characteristics of≥0℃ and≥10℃ active accumulated temperature(AAT0,AAT10)in WS and ES were analyzed comprehensively using 5-day average sliding,empirical orthogonal function(EOF),ensemble empirical mode decomposition(EEMD),and multiple mutation tests.The results show that(1)AAT0 and AAT10 of WS ranged from 3034℃ to 3586℃ and 1971℃ to 2636℃,respectively,while the AAT0 and AAT10 of ES ranged from 5863℃ to 6513℃ and 4847℃ to 5875℃,respectively.The period around 1997 was a significant abrupt change,and the AAT in the province generally increased during the subsequent time period(2)AAT in the study area is mainly driven by the fluctuations of AMO,as reflected by the low-to-high variation of AAT coinciding with the jump of the cold-to-warm phase of AMO.Considering different time scale fluctuations in the past 51 years,the major cycle for both AAT0 and AAT10 in WS is 3.40 a,while the major cycles in ES are 3.64 a and 3.19 a,respectively with a sub-cycle of 7.29 a.AAT fluctuation has an insignificant periodic characteristic of 25.50 a on the interdecadal scale(3)The spatial heterogeneity of AAT in WS is prominent and is mainly reflected by the significantly warm conditions in the south of the WS region and relatively slight warm conditions in the north,as well as by the isolated cooling area in the form of"freezing point",i.e.,Xiaojin county.In contrast,the spatial variability of AAT in ES is more or less consistent,with the warming areas concentrated in the foothills of the western edge of the basin and a slight increase in AAT observed in the central part of the basin.展开更多
Modified suction caissons(MSCs)acting as offshore wind turbine foundations will generate the accumulated rotation under cyclic loading resulted from waves.The accumulated rotation and the range of soil deformation aro...Modified suction caissons(MSCs)acting as offshore wind turbine foundations will generate the accumulated rotation under cyclic loading resulted from waves.The accumulated rotation and the range of soil deformation around the MSC under long-term cyclic wave loading were studied using 3-D numerical simulations.The Morison equation was adopted to calculate the wave loadings.It was found that the MSC accumulated rotation increases linearly with the increase of the logarithm of cyclic number.The normalized expression was proposed to reflect the relationship between the accumulated rotation and cyclic number.The soil deformation range around the MSC increases when increasing the cyclic number and loading amplitude.It can also be concluded that the accumulated rotation increases rapidly with this change of excess pore pressure in the first 4000 cycles.The responses of the MSC to wave and wind loads were also investigated.Results show that the accumulated rotation of the MSC under both wave and wind loadings is larger than that under the wave loading only.展开更多
In this study,accumulated extrusion bonding(AEB)process with application of artificial water cooling was successfully performed to fabricate fined-grains AZ31B Mg alloy sheets at 150℃,200℃ and 250℃.The resultant mi...In this study,accumulated extrusion bonding(AEB)process with application of artificial water cooling was successfully performed to fabricate fined-grains AZ31B Mg alloy sheets at 150℃,200℃ and 250℃.The resultant microstructure and mechanical properties are systematically investigated.It reveals that the processing temperature has an important effect on the microstructural evolution during extrusion.During AEB process at 150℃ and 200℃,{10-12}tensile twinning was activated at early stage of extrusion,and subsequently continuous dynamic recrystallization(CDRX)occurred and dominated the further deformation.However,for the sample extruded at 250℃,hardly any twins can be observed,and new fined dynamic recrystallized grains were found along grain boundaries.Artificial cooling was utilized to reduce the rate of grain growth out of the extrusion die,resulting the grains significantly refined from 11μm to 2.5μm.Local high dislocation density region was also observed in the microstructure of sample processed at 150℃ in artificial cooling condition,and the degree decreased with the processing temperature increase.The results summarized from tensile tests indicated that due to the grain refinement the strength and ductility was significantly enhanced(YS of 186 MPa vs.145 MPa,UTS of 391 MPa vs.336 MPa and FE of 31.5%vs.24.5%compared with the as-received sample).Subsequently,annealing treatment at different temperatures was applied to eliminate the high dislocation density.The sample annealed at 200℃ exhibited the best comprehensive mechanical property with YS of 179 MPa,UTS of 390 MPa and FE of 33.0%.As the annealing temperature increasing,the dislocation density was reduced by static recrystallization(SRX)and grain growth,leading to a decreased strength and ductility.展开更多
Laser scanning confocal endomicroscope(LSCEM)has emerged as an imaging modality which provides noninvasive,in vivo imaging of biological tissue on a microscopic scale.Scientific visualizations for LSCEM datasets captu...Laser scanning confocal endomicroscope(LSCEM)has emerged as an imaging modality which provides noninvasive,in vivo imaging of biological tissue on a microscopic scale.Scientific visualizations for LSCEM datasets captured by current imaging systems require these datasets to be fully acquired and brought to a separate rendering machine.To extend the features and capabilities of this modality,we propose a system which is capable of performing realtime visualization of LSCEM datasets.Using field-programmable gate arrays,our system performs three tasks in parallel:(1)automated control of dataset acquisition;(2)imaging-rendering system synchronization;and(3)realtime volume rendering of dynamic datasets.Through fusion of LSCEM imaging and volume rendering processes,acquired datasets can be visualized in realtime to provide an immediate perception of the image quality and biological conditions of the subject,further assisting in realtime cancer diagnosis.Subsequently,the imaging procedure can be improved for more accurate diagnosis and reduce the need for repeating the process due to unsatisfactory datasets.展开更多
Global warming has become a topic of widespread attention. The climate change will affect the change of agricultural climate resource,thereby affecting the agricultural planting structure,the grain yield,etc. Based on...Global warming has become a topic of widespread attention. The climate change will affect the change of agricultural climate resource,thereby affecting the agricultural planting structure,the grain yield,etc. Based on the daily temperature of Zhangjiakou from 1960 to 2011,the temporal changes of ≥0 ℃ and ≥10 ℃ accumulated temperatures were analyzed by using the methods of linear trend estimation and M-K mutation test. The results indicated that(1) the annual average temperature showed an increasing trend with the linear warming rate of 0. 42 ℃ /10 a in the past 52 years. In 1982,the annual average temperature had abrupt change,especially after 1983,the warming trend increased significantly.(2) In the past 52 years,≥0 ℃ accumulated temperature showed an increasing trend with the warming rate of 89. 4 ℃ /10 a. Mutation point of ≥0 ℃ accumulated temperature appeared in 1983,and after 1985,≥0 ℃ accumulated temperature increased sharply. At the same time,the ≥10 ℃ accumulated temperature had abrupt change in 1983,especially from 1987 to 1995 and after 1986,the warming trend increased sharply.(3) The initial date of ≥0 ℃ presented significant advancing trend,and that of ≥10 ℃ had little change,while their terminal dates presented delaying trend,so the sustained days of ≥0 ℃ and ≥10 ℃ increased significantly.(4) In the past 52 years,the delay of the terminal dates of ≥0 ℃ and ≥10 ℃ was greater than the advancing of the initial dates,and ≥0 ℃ accumulated temperature had a greater increase than ≥10 ℃ accumulated temperature.展开更多
[Objective] The aim was to study the change trend of accumulated temperature in Shenyang in recent 58 years, as well as its effect on agricultural production. [Method] Based on the surface temperature data in Shenyang...[Objective] The aim was to study the change trend of accumulated temperature in Shenyang in recent 58 years, as well as its effect on agricultural production. [Method] Based on the surface temperature data in Shenyang, the change trends of ≥0 ℃ and ≥10 ℃ accumulated temperature in Shenyang in recent 58 years were analyzed by means of climatic statistics method, and the effects of accumulated temperature variation on agricultural production were discussed. [Result] In recent 58 years, the first day with temperature ≥0 ℃ advanced 10 d, and the last day put off slightly, while sustained days prolonged 13 d, and ≥0 ℃ accumulated temperature increased by 343 ℃·d; meanwhile, the first day with temperature ≥10 ℃ advanced 9 d, and the last day put off 8 d, while sustained days prolonged 16 d, and ≥10 ℃ accumulated temperature increased by 370 ℃·d; compared with the first 20 years, sustained days with temperature ≥0 ℃ and ≥10 ℃ prolonged 9 d in the last 20 years, and ≥0 ℃ and ≥10 ℃ accumulated temperature increased by 196 and 202 ℃·d, respectively. In addition, the increase of heat resources affected agricultural production in Shenyang. [Conclusion] The study could provide theoretical foundation for grasping heat resources variation and adjusting agriculture distribution.展开更多
Accumulated temperature,which is now widely used in agronomy,is an important ecological factor to the growth of plants,but few relative studies have been found on the vegetation area of floodplain grasslands in Poyang...Accumulated temperature,which is now widely used in agronomy,is an important ecological factor to the growth of plants,but few relative studies have been found on the vegetation area of floodplain grasslands in Poyang Lake.This research used the classification and regression tree(CART)to classify normalized vegetation area index derived from MODIS LAI(Moderate Resolution Imaging Spectroradiometer Leaf Area Index)images from 2008 to 2014,according to different climate indexes,such as mean daily air temperature(n),accumulated temperature(jw),daily maximum temperature(g),daily minimum temperature(d),accumulative precipitation(j),water level(s)and average water level for 20 days preceding(a).The results showed that:(1)The accumulated temperature and the 20-day average WL(water level)were found to have the greatest impact on variation in wetland vegetation area,and they both dominated the classification process twice;(2)Two classification thresholds of accumulated temperature were 790°C and 1784°C,approximately corresponding to the beginning of April and midMay;(3)790°C could also be used as a threshold to select remote sensing images to analysis the annual variability of vegetation,i.e.while accumulated temperature is lower than 790°C,remote sensing images of similar accumulated temperature rather than similar date should be selected from different years for comparison.We also found that,effects of different hydrological factors on area of floodplain grasslands showed stage characteristics:(1)From January to March,water level changes slowly with less rainfall,as a result,the 20-day average WL which can interpret the hydrologic characteristics smoothly showed significant importance in this stage;(2)While entering April,intense rainfall make accumulative precipitation to be the dominating factor of classification;(3)From late April to mid-May,in condition of accumulative precipitation higher than 405 mm,daily water level is of most importance,because to the flood recession process as well as rapid water level fluctuations.展开更多
Accumulated sand-belts refer to those formed along the oasis fringe,especially at the upwind location,due to the accumulation of sand blocked by farmland windbreak. In the 60 years since the foundation of new China,a ...Accumulated sand-belts refer to those formed along the oasis fringe,especially at the upwind location,due to the accumulation of sand blocked by farmland windbreak. In the 60 years since the foundation of new China,a lot of trees have been planted for desertification combating in northwest and north China,thus,accumulated sand-belts were formed at the upwind location. The formation and the ecological effects of the accumulated sand-belts along the oasis fringe is a new scientific concern. To study the formation causes of these belts in Hexi corridor,21 samples were selected,and the height / width of the belts,as well as the vegetation,soil,soil moisture and climatic factors were investigated. This paper analyzed the correlation between the height / width of the belts and the vegetation,soil,soil moisture and climatic factors using the methods of variance analysis,correlation analysis and canonical correlation analysis. The results indicate that: the accumulated sand-belts take a trend of being high and wide in the east whereas low and narrow in the west,and most of the parts tend to be stable; the species on the belts are dominated by Tamarix austromongolica,the vegetation cover and the pure vegetation cover of different dominant species on the leeward slope of the accumulated sand-belts vary significantly. The canonical correlation analysis shows that: the height and width of accumulated sand-belt is the interaction of precipitation,distance to the sand source,leeward vegetation cover and annual average wind speed. Moreover,the height of accumulated sand-belts are negatively correlated to the soil moisture at the depth of 30- 50 cm,air humidity and leeward vegetation cover,and the width of the belts is also negatively correlated with the distance to the sand source. The ecological effects of the accumulated sand-belts are both positive( stopping sands from moving into farmland,protective role as an obstacle)and negative( when the belts decay and activate one day,they will become the new sand sources). At present,there are no signs showing the negative effects of the belts. The ecological effects of the accumulated sand-belts are: firstly the protective role as an obstacle,and secondly to intercept and reduce the sands moving into farmlands.展开更多
Five rice varieties were planted to determine the variation of the yield and quality traits in five different regions in a cold area of China. The results showed that the number of the panicles, the number of grains p...Five rice varieties were planted to determine the variation of the yield and quality traits in five different regions in a cold area of China. The results showed that the number of the panicles, the number of grains per panicle and percentage of head-milled rice displayed quadratic curves against the accumulated temperature, and the sterile rate decreased with greater accumulated temperature. However, 1 000-grain weight had no correlation with the accumulated temperature and protein content, amylose content and taste also had no obvious relation with the accumulated temperature. The results from the accumulated temperature differed with rice variety, so the temperature insensitive type variety should be proposed for production.展开更多
Applying the reciprocal accumulated generating and the reconstruction method of GRM(1,1) model’s background value of non-equidistant sequence based on the exponential trait of grey model and the definition of integra...Applying the reciprocal accumulated generating and the reconstruction method of GRM(1,1) model’s background value of non-equidistant sequence based on the exponential trait of grey model and the definition of integral for the problem of lower precision as well as lower adaptability in non-equidistant GM(1,1) model, the calculation formulas were deduced and a novel non-equidistant GRM(1,1) model generated by reciprocal accumulated generating was put forward. The grey GRM(1,1) model can be used in non-equidistant interval & equidistant interval time series and has the characteristic of high precision as well as high adaptability. Example validates the practicability and reliability of the proposed model.展开更多
Aiming the problem of low accuracy during establishing grey model in which monotonically decreasing sequence data and traditional modeling methods are used, this paper applied the reciprocal accumulated generating and...Aiming the problem of low accuracy during establishing grey model in which monotonically decreasing sequence data and traditional modeling methods are used, this paper applied the reciprocal accumulated generating and the approach optimizing grey derivative which is based on three points to deduce the calculation formulas for model parameters, established grey GRM(1, 1) model based on reciprocal accumulated generating. It provides a new method for the grey modeling. The example validates the practicability and reliability of the proposed model.展开更多
Background: To improve negative birth experiences among women who experience intense labor pain during labor, it is important to examine the relationship between fear of childbirth immediately after vaginal delivery a...Background: To improve negative birth experiences among women who experience intense labor pain during labor, it is important to examine the relationship between fear of childbirth immediately after vaginal delivery and the actual intensity of labor pain. However, previous studies have generally evaluated labor pain in a retrospective setting. Purpose: This study examined the relationship between fear of childbirth immediately after vaginal delivery and the actual labor pain intensity and accumulated labor pain intensity without pharmacological pain relief during labor in Japan. Methods: A prospective observational study was conducted between July 2015 and April 2016. Forty-seven pregnant Japanese women were available for analysis. Fear of childbirth was measured by the Japanese version of the Wijma Delivery Expectancy/Experience Questionnaire (JW-DEQ) version B on the third day after vaginal delivery. Participants with scores of 85 or higher were categorized in the high JW-DEQ group, having severe fear of childbirth. Labor pain intensity was examined chronologically in real time with stepwise usage of two types of Numeric Rating Scale (NRS). Accumulated labor pain intensity was calculated using the area under the curve (AUC). Results: Nine participants were in the high JW-DEQ group and eight of the nine were primiparae. Primiparae in the high JW-DEQ group experienced significantly longer duration and larger accumulated labor pain intensity between the onset of labor and 4 to 6 cm of cervical dilatation than those in the low JW-DEQ group (P = 0.024 and P = 0.021, respectively). Conclusions/Implications for Practice: The latent phase of labor was a key stage to improve fear of childbirth immediately after vaginal delivery without pharmacological pain relief among Japanese primiparae. Midwives should give assistance in the latent phase of labor by focusing on progressing labor smoothly and relieving labor pain to improve negative birth experiences.展开更多
Objective: To study the effect of Modified and accumulated Decoction on serum ER, PR, sex hormone, IGF-I and IGF-I in patients with uterine fibroids. Method: A total of 90 patients with uterine fibroids in our hospita...Objective: To study the effect of Modified and accumulated Decoction on serum ER, PR, sex hormone, IGF-I and IGF-I in patients with uterine fibroids. Method: A total of 90 patients with uterine fibroids in our hospital from January 2015 to January 2017 were enrolled in this study. The subjects were divided into the control group (n=45) and the treatment group (n=45) randomly. The control group was treated with mifepristone, the treatment group was treated with Modified and accumulated Decoction combined with mifepristone, and both the two groups were treated for 3 months. The uterine fibroid volume and uterine volume of the two groups before and after treatment were compared. The serum ER, PR, P, E2, LH, FSH, IGF-I and IGF-IR of the two groups before and after treatment were compared. Result: There were no significantly differences of the uterine fibroid volume and uterine volume of the two groups before treatment. The uterine fibroid volume and uterine volume of the two groups after treatment were significantly less than before treatment, and that of the treatment group after treatment were significantly less than the control group. There were no significantly differences among the serum ER, PR, P, E2, LH, FSH, IGF-I and IGF-IR of the two groups before treatment. The serum ER, PR, P, E2, LH, FSH, IGF-I and IGF-IR of the two groups after treatment were significantly lower than before treatment, and that of the treatment group after treatment were significantly lower than the control group. Conclusion: Modified and accumulated Decoction combined with mifepristonecan significantly reduce the uterine fibroid volume, improve the serum ER, PR, sex hormone, IGF-I and IGF-I levels of the patients with uterine fibroids, and it was worthy clinical application.展开更多
The personal account of new rural social pension insurance raises funds in the form of individual premium-paying,collectively pooled subsidy and government subsidy.The personal account accumulated value has a decisive...The personal account of new rural social pension insurance raises funds in the form of individual premium-paying,collectively pooled subsidy and government subsidy.The personal account accumulated value has a decisive influence on the payment level of personal account pension.The personal account accumulated value has a direct or indirect relationship with the income level of farmers,premium-paying level,the insured period,investment return rate of funds and other factors.Analysing the impact of infinitesimal variation of these factors on accumulated value of personal account pension,is of great significance to improving and consolidating personal account,and achieving sustainable development of new rural social pension insurance.展开更多
AZ31/Mg3Y composites with a layer thickness of 100-200μm were fabricated by accumulated rolling bonding(ARB),which was followed by diffusion annealing at 300℃ for 0-32 h.An interface layer,containing numerous Al-Y p...AZ31/Mg3Y composites with a layer thickness of 100-200μm were fabricated by accumulated rolling bonding(ARB),which was followed by diffusion annealing at 300℃ for 0-32 h.An interface layer,containing numerous Al-Y precipitates,is formed in the Mg3Y layer that is adjacent to the interface as a result of Al diffusing from the AZ31 layers into the Mg3Y layers.The thickness of the interface layer gets increased and more precipitates are formed in the interface layer with the extension of the annealing time.The microhardness of the AZ31 and Mg3Y layer decreases firstly and then reaches a stable value,while the microhardness of the interface layer increases gradually with the extension of the annealing time.The AZ31/Mg3Y composites exhibit equivalent strength but increased ductility after diffusion annealing,in comparison to the as-rolled AZ31/Mg3Y composite.In addition,the AZ31/Mg3Y composites after annealing always present higher strength and ductility than AZ31/AZ31 composite,which was fabricated by the same process as that for the AZ31/Mg3Y composites.Hetero-deformation induced strengthening also plays an important role in the excellent strength and ductility of the annealed AZ31/Mg3Y composite.This study can provide a direction for improving the plasticity and strength of magnesium alloys synergistically.展开更多
In cold regions,the thermal effect of accumulated water on underlying permafrost and permafrost subgrade remains a significant hazard causing engineering risks.Water depth of accumulated water may be an important infl...In cold regions,the thermal effect of accumulated water on underlying permafrost and permafrost subgrade remains a significant hazard causing engineering risks.Water depth of accumulated water may be an important influence factor of permafrost thermal stability,but there is lack of qualitative and quantitative research about that.In this study,equivalent thermal conductivity theory and solid heat transfer theory have been used to establish the calculation model for simulating heat transfer in water and soil.Thereafter,the accuracy and reliability of the calculation model are checked by monitored data and subsequently used to analyze the thermal erosion of water on underlying permafrost and permafrost under the embankment.These simulation results show that shallow water can protect permafrost and deeper water disrupts the thermal stability of underlying permafrost.The thermal effect extent of water is primarily determined by its depth,and the concept of critical depth and stable depth of accumulated water has been proposed.Moreover,the temperature field of permafrost under embankment can be changed by the slope toe water.In addition,the thermal effect range of the slope toe water is limited by the thermal influence radius,which increases with the depth of standing water.These findings provide support as well as a fundamental base for environmental issues arising from the accumulated water.These observations will,thus,also be valuable to further engineering environment studies in cold regions.展开更多
基金The authors are grateful for the National Natural Science Foundation of China(No.51905366 and U1810122)Yantai high-end talent introduction"Double Hundred Plan"(2021)Key Research and Development Program of Shanxi Province(201903D421076).
文摘AZ31 Mg alloy with heterogeneous bimodal grain structure(smaller grain size of 5-20µm and coarser grain size of 100-200µm)was subjected to accumulated extrusion bonding(AEB)at 250℃combined with two-stage artificial cooling in this work,viz.local water cooling and artificial cooling.The microstructure developed consecutively as a result of discontinuous dynamic recrystallization(DDRX)for the AEBed samples.{10-12}tensile twinning also played an important role for the AEB with local water cooling at the initial extrusion stage in the container.Local water cooling could further reduce the DRXed grain size to~2.1µm comparing that without water cooling.And the grain growth rate was reduced by artificial cooling out of extrusion die.Under the combination of two-stage cooling,the fine DRXed grains at sizing band were almost retained with average grain size of~2.3µm after the sheet out of extrusion die,and the unDRXed grains with high residual dislocation density accumulation were also reserved.The tensile tests results indicated that a good strength-ductility balance with a high ultimate tensile strength(319 MPa vs.412 MPa)and fracture elongation(19.9%vs.30.3%)were obtained.The strength enhancement was mainly owing to the grain refinement and local residual plastic strain reserved by the artificial cooling.The excellent ductility originated from fine DRXed microstructure and ED-tilt double peak texture.
基金the National Natural Science Foundation of China(Grant No.51779114)。
文摘It is of utmost necessity to understand the dynamics of regional active accumulated temperature(AAT)to cope with the negative impacts of global warming on agroforestry development and food security and to provide a real-time and effective reference basis for regional agroforestry planning.The daily temperature data from 30 meteorological stations in Sichuan Province from 1970 to 2020,and sea surface temperature(SST)index data from the Atlantic Multiphase Oscillation(AMO)and Pacific Decadal Oscillation(PDO)were used for the study.Sichuan Province was divided into the western region(WS)and the eastern region(ES),considering 1000 m above sea level as the boundary.The spatiotemporal characteristics of≥0℃ and≥10℃ active accumulated temperature(AAT0,AAT10)in WS and ES were analyzed comprehensively using 5-day average sliding,empirical orthogonal function(EOF),ensemble empirical mode decomposition(EEMD),and multiple mutation tests.The results show that(1)AAT0 and AAT10 of WS ranged from 3034℃ to 3586℃ and 1971℃ to 2636℃,respectively,while the AAT0 and AAT10 of ES ranged from 5863℃ to 6513℃ and 4847℃ to 5875℃,respectively.The period around 1997 was a significant abrupt change,and the AAT in the province generally increased during the subsequent time period(2)AAT in the study area is mainly driven by the fluctuations of AMO,as reflected by the low-to-high variation of AAT coinciding with the jump of the cold-to-warm phase of AMO.Considering different time scale fluctuations in the past 51 years,the major cycle for both AAT0 and AAT10 in WS is 3.40 a,while the major cycles in ES are 3.64 a and 3.19 a,respectively with a sub-cycle of 7.29 a.AAT fluctuation has an insignificant periodic characteristic of 25.50 a on the interdecadal scale(3)The spatial heterogeneity of AAT in WS is prominent and is mainly reflected by the significantly warm conditions in the south of the WS region and relatively slight warm conditions in the north,as well as by the isolated cooling area in the form of"freezing point",i.e.,Xiaojin county.In contrast,the spatial variability of AAT in ES is more or less consistent,with the warming areas concentrated in the foothills of the western edge of the basin and a slight increase in AAT observed in the central part of the basin.
基金the National Natural Science Foundation of China(Grant Nos.51639002,51879044 and 51808325)SDUST(Shandong University of Science and Technology)Research Fund(Grant No.2015KYTD104).
文摘Modified suction caissons(MSCs)acting as offshore wind turbine foundations will generate the accumulated rotation under cyclic loading resulted from waves.The accumulated rotation and the range of soil deformation around the MSC under long-term cyclic wave loading were studied using 3-D numerical simulations.The Morison equation was adopted to calculate the wave loadings.It was found that the MSC accumulated rotation increases linearly with the increase of the logarithm of cyclic number.The normalized expression was proposed to reflect the relationship between the accumulated rotation and cyclic number.The soil deformation range around the MSC increases when increasing the cyclic number and loading amplitude.It can also be concluded that the accumulated rotation increases rapidly with this change of excess pore pressure in the first 4000 cycles.The responses of the MSC to wave and wind loads were also investigated.Results show that the accumulated rotation of the MSC under both wave and wind loadings is larger than that under the wave loading only.
基金the National Natural Science Foundation of China(No.51905366,51901149,51671041,51604181,U1910213 and U1610253)the Key Research and Development Program of Shanxi Province(No.201603D111004)+1 种基金the Fund for Shanxi“1331 Project”Key Subjects Construction,Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi(No.2019L0632)Taiyuan University of Science and Technology Scientific Research Initial Funding(20182030,20192003 and 20192008)。
文摘In this study,accumulated extrusion bonding(AEB)process with application of artificial water cooling was successfully performed to fabricate fined-grains AZ31B Mg alloy sheets at 150℃,200℃ and 250℃.The resultant microstructure and mechanical properties are systematically investigated.It reveals that the processing temperature has an important effect on the microstructural evolution during extrusion.During AEB process at 150℃ and 200℃,{10-12}tensile twinning was activated at early stage of extrusion,and subsequently continuous dynamic recrystallization(CDRX)occurred and dominated the further deformation.However,for the sample extruded at 250℃,hardly any twins can be observed,and new fined dynamic recrystallized grains were found along grain boundaries.Artificial cooling was utilized to reduce the rate of grain growth out of the extrusion die,resulting the grains significantly refined from 11μm to 2.5μm.Local high dislocation density region was also observed in the microstructure of sample processed at 150℃ in artificial cooling condition,and the degree decreased with the processing temperature increase.The results summarized from tensile tests indicated that due to the grain refinement the strength and ductility was significantly enhanced(YS of 186 MPa vs.145 MPa,UTS of 391 MPa vs.336 MPa and FE of 31.5%vs.24.5%compared with the as-received sample).Subsequently,annealing treatment at different temperatures was applied to eliminate the high dislocation density.The sample annealed at 200℃ exhibited the best comprehensive mechanical property with YS of 179 MPa,UTS of 390 MPa and FE of 33.0%.As the annealing temperature increasing,the dislocation density was reduced by static recrystallization(SRX)and grain growth,leading to a decreased strength and ductility.
文摘Laser scanning confocal endomicroscope(LSCEM)has emerged as an imaging modality which provides noninvasive,in vivo imaging of biological tissue on a microscopic scale.Scientific visualizations for LSCEM datasets captured by current imaging systems require these datasets to be fully acquired and brought to a separate rendering machine.To extend the features and capabilities of this modality,we propose a system which is capable of performing realtime visualization of LSCEM datasets.Using field-programmable gate arrays,our system performs three tasks in parallel:(1)automated control of dataset acquisition;(2)imaging-rendering system synchronization;and(3)realtime volume rendering of dynamic datasets.Through fusion of LSCEM imaging and volume rendering processes,acquired datasets can be visualized in realtime to provide an immediate perception of the image quality and biological conditions of the subject,further assisting in realtime cancer diagnosis.Subsequently,the imaging procedure can be improved for more accurate diagnosis and reduce the need for repeating the process due to unsatisfactory datasets.
文摘Global warming has become a topic of widespread attention. The climate change will affect the change of agricultural climate resource,thereby affecting the agricultural planting structure,the grain yield,etc. Based on the daily temperature of Zhangjiakou from 1960 to 2011,the temporal changes of ≥0 ℃ and ≥10 ℃ accumulated temperatures were analyzed by using the methods of linear trend estimation and M-K mutation test. The results indicated that(1) the annual average temperature showed an increasing trend with the linear warming rate of 0. 42 ℃ /10 a in the past 52 years. In 1982,the annual average temperature had abrupt change,especially after 1983,the warming trend increased significantly.(2) In the past 52 years,≥0 ℃ accumulated temperature showed an increasing trend with the warming rate of 89. 4 ℃ /10 a. Mutation point of ≥0 ℃ accumulated temperature appeared in 1983,and after 1985,≥0 ℃ accumulated temperature increased sharply. At the same time,the ≥10 ℃ accumulated temperature had abrupt change in 1983,especially from 1987 to 1995 and after 1986,the warming trend increased sharply.(3) The initial date of ≥0 ℃ presented significant advancing trend,and that of ≥10 ℃ had little change,while their terminal dates presented delaying trend,so the sustained days of ≥0 ℃ and ≥10 ℃ increased significantly.(4) In the past 52 years,the delay of the terminal dates of ≥0 ℃ and ≥10 ℃ was greater than the advancing of the initial dates,and ≥0 ℃ accumulated temperature had a greater increase than ≥10 ℃ accumulated temperature.
基金Supported by Scientific Research Project of Shenyang Science and Technology Bureau([2010]Number 15)
文摘[Objective] The aim was to study the change trend of accumulated temperature in Shenyang in recent 58 years, as well as its effect on agricultural production. [Method] Based on the surface temperature data in Shenyang, the change trends of ≥0 ℃ and ≥10 ℃ accumulated temperature in Shenyang in recent 58 years were analyzed by means of climatic statistics method, and the effects of accumulated temperature variation on agricultural production were discussed. [Result] In recent 58 years, the first day with temperature ≥0 ℃ advanced 10 d, and the last day put off slightly, while sustained days prolonged 13 d, and ≥0 ℃ accumulated temperature increased by 343 ℃·d; meanwhile, the first day with temperature ≥10 ℃ advanced 9 d, and the last day put off 8 d, while sustained days prolonged 16 d, and ≥10 ℃ accumulated temperature increased by 370 ℃·d; compared with the first 20 years, sustained days with temperature ≥0 ℃ and ≥10 ℃ prolonged 9 d in the last 20 years, and ≥0 ℃ and ≥10 ℃ accumulated temperature increased by 196 and 202 ℃·d, respectively. In addition, the increase of heat resources affected agricultural production in Shenyang. [Conclusion] The study could provide theoretical foundation for grasping heat resources variation and adjusting agriculture distribution.
基金This work was supported by the National Natural Science Foundation of China“Study on the dynamic mechanism of grassland ecosystem response to climate change in Qinghai Plateau”under grant number U20A2098the Second Tibet Plateau Scientific Expedition and Research Program(STEP)under grant number 2019QZKK0804.
文摘Accumulated temperature,which is now widely used in agronomy,is an important ecological factor to the growth of plants,but few relative studies have been found on the vegetation area of floodplain grasslands in Poyang Lake.This research used the classification and regression tree(CART)to classify normalized vegetation area index derived from MODIS LAI(Moderate Resolution Imaging Spectroradiometer Leaf Area Index)images from 2008 to 2014,according to different climate indexes,such as mean daily air temperature(n),accumulated temperature(jw),daily maximum temperature(g),daily minimum temperature(d),accumulative precipitation(j),water level(s)and average water level for 20 days preceding(a).The results showed that:(1)The accumulated temperature and the 20-day average WL(water level)were found to have the greatest impact on variation in wetland vegetation area,and they both dominated the classification process twice;(2)Two classification thresholds of accumulated temperature were 790°C and 1784°C,approximately corresponding to the beginning of April and midMay;(3)790°C could also be used as a threshold to select remote sensing images to analysis the annual variability of vegetation,i.e.while accumulated temperature is lower than 790°C,remote sensing images of similar accumulated temperature rather than similar date should be selected from different years for comparison.We also found that,effects of different hydrological factors on area of floodplain grasslands showed stage characteristics:(1)From January to March,water level changes slowly with less rainfall,as a result,the 20-day average WL which can interpret the hydrologic characteristics smoothly showed significant importance in this stage;(2)While entering April,intense rainfall make accumulative precipitation to be the dominating factor of classification;(3)From late April to mid-May,in condition of accumulative precipitation higher than 405 mm,daily water level is of most importance,because to the flood recession process as well as rapid water level fluctuations.
基金Supported by the Pre-phase Project of the 973 Program(2014CB460611)
文摘Accumulated sand-belts refer to those formed along the oasis fringe,especially at the upwind location,due to the accumulation of sand blocked by farmland windbreak. In the 60 years since the foundation of new China,a lot of trees have been planted for desertification combating in northwest and north China,thus,accumulated sand-belts were formed at the upwind location. The formation and the ecological effects of the accumulated sand-belts along the oasis fringe is a new scientific concern. To study the formation causes of these belts in Hexi corridor,21 samples were selected,and the height / width of the belts,as well as the vegetation,soil,soil moisture and climatic factors were investigated. This paper analyzed the correlation between the height / width of the belts and the vegetation,soil,soil moisture and climatic factors using the methods of variance analysis,correlation analysis and canonical correlation analysis. The results indicate that: the accumulated sand-belts take a trend of being high and wide in the east whereas low and narrow in the west,and most of the parts tend to be stable; the species on the belts are dominated by Tamarix austromongolica,the vegetation cover and the pure vegetation cover of different dominant species on the leeward slope of the accumulated sand-belts vary significantly. The canonical correlation analysis shows that: the height and width of accumulated sand-belt is the interaction of precipitation,distance to the sand source,leeward vegetation cover and annual average wind speed. Moreover,the height of accumulated sand-belts are negatively correlated to the soil moisture at the depth of 30- 50 cm,air humidity and leeward vegetation cover,and the width of the belts is also negatively correlated with the distance to the sand source. The ecological effects of the accumulated sand-belts are both positive( stopping sands from moving into farmland,protective role as an obstacle)and negative( when the belts decay and activate one day,they will become the new sand sources). At present,there are no signs showing the negative effects of the belts. The ecological effects of the accumulated sand-belts are: firstly the protective role as an obstacle,and secondly to intercept and reduce the sands moving into farmlands.
基金Supported by the Public Industry Project of Ministry of Agriculture(201303126)Postdoctoral Fund of Heilongjiang Province(LBH-Z13189)Innovation Project of Institute(2012ZD013)
文摘Five rice varieties were planted to determine the variation of the yield and quality traits in five different regions in a cold area of China. The results showed that the number of the panicles, the number of grains per panicle and percentage of head-milled rice displayed quadratic curves against the accumulated temperature, and the sterile rate decreased with greater accumulated temperature. However, 1 000-grain weight had no correlation with the accumulated temperature and protein content, amylose content and taste also had no obvious relation with the accumulated temperature. The results from the accumulated temperature differed with rice variety, so the temperature insensitive type variety should be proposed for production.
文摘Applying the reciprocal accumulated generating and the reconstruction method of GRM(1,1) model’s background value of non-equidistant sequence based on the exponential trait of grey model and the definition of integral for the problem of lower precision as well as lower adaptability in non-equidistant GM(1,1) model, the calculation formulas were deduced and a novel non-equidistant GRM(1,1) model generated by reciprocal accumulated generating was put forward. The grey GRM(1,1) model can be used in non-equidistant interval & equidistant interval time series and has the characteristic of high precision as well as high adaptability. Example validates the practicability and reliability of the proposed model.
文摘Aiming the problem of low accuracy during establishing grey model in which monotonically decreasing sequence data and traditional modeling methods are used, this paper applied the reciprocal accumulated generating and the approach optimizing grey derivative which is based on three points to deduce the calculation formulas for model parameters, established grey GRM(1, 1) model based on reciprocal accumulated generating. It provides a new method for the grey modeling. The example validates the practicability and reliability of the proposed model.
文摘Background: To improve negative birth experiences among women who experience intense labor pain during labor, it is important to examine the relationship between fear of childbirth immediately after vaginal delivery and the actual intensity of labor pain. However, previous studies have generally evaluated labor pain in a retrospective setting. Purpose: This study examined the relationship between fear of childbirth immediately after vaginal delivery and the actual labor pain intensity and accumulated labor pain intensity without pharmacological pain relief during labor in Japan. Methods: A prospective observational study was conducted between July 2015 and April 2016. Forty-seven pregnant Japanese women were available for analysis. Fear of childbirth was measured by the Japanese version of the Wijma Delivery Expectancy/Experience Questionnaire (JW-DEQ) version B on the third day after vaginal delivery. Participants with scores of 85 or higher were categorized in the high JW-DEQ group, having severe fear of childbirth. Labor pain intensity was examined chronologically in real time with stepwise usage of two types of Numeric Rating Scale (NRS). Accumulated labor pain intensity was calculated using the area under the curve (AUC). Results: Nine participants were in the high JW-DEQ group and eight of the nine were primiparae. Primiparae in the high JW-DEQ group experienced significantly longer duration and larger accumulated labor pain intensity between the onset of labor and 4 to 6 cm of cervical dilatation than those in the low JW-DEQ group (P = 0.024 and P = 0.021, respectively). Conclusions/Implications for Practice: The latent phase of labor was a key stage to improve fear of childbirth immediately after vaginal delivery without pharmacological pain relief among Japanese primiparae. Midwives should give assistance in the latent phase of labor by focusing on progressing labor smoothly and relieving labor pain to improve negative birth experiences.
文摘Objective: To study the effect of Modified and accumulated Decoction on serum ER, PR, sex hormone, IGF-I and IGF-I in patients with uterine fibroids. Method: A total of 90 patients with uterine fibroids in our hospital from January 2015 to January 2017 were enrolled in this study. The subjects were divided into the control group (n=45) and the treatment group (n=45) randomly. The control group was treated with mifepristone, the treatment group was treated with Modified and accumulated Decoction combined with mifepristone, and both the two groups were treated for 3 months. The uterine fibroid volume and uterine volume of the two groups before and after treatment were compared. The serum ER, PR, P, E2, LH, FSH, IGF-I and IGF-IR of the two groups before and after treatment were compared. Result: There were no significantly differences of the uterine fibroid volume and uterine volume of the two groups before treatment. The uterine fibroid volume and uterine volume of the two groups after treatment were significantly less than before treatment, and that of the treatment group after treatment were significantly less than the control group. There were no significantly differences among the serum ER, PR, P, E2, LH, FSH, IGF-I and IGF-IR of the two groups before treatment. The serum ER, PR, P, E2, LH, FSH, IGF-I and IGF-IR of the two groups after treatment were significantly lower than before treatment, and that of the treatment group after treatment were significantly lower than the control group. Conclusion: Modified and accumulated Decoction combined with mifepristonecan significantly reduce the uterine fibroid volume, improve the serum ER, PR, sex hormone, IGF-I and IGF-I levels of the patients with uterine fibroids, and it was worthy clinical application.
基金Supported by Scientific Research Project of Hunan Provincial Department of Education(11C1180)
文摘The personal account of new rural social pension insurance raises funds in the form of individual premium-paying,collectively pooled subsidy and government subsidy.The personal account accumulated value has a decisive influence on the payment level of personal account pension.The personal account accumulated value has a direct or indirect relationship with the income level of farmers,premium-paying level,the insured period,investment return rate of funds and other factors.Analysing the impact of infinitesimal variation of these factors on accumulated value of personal account pension,is of great significance to improving and consolidating personal account,and achieving sustainable development of new rural social pension insurance.
基金This work was financially supported by the National Natural Science Foundation of China(Projects 52171102,51971041)the Fundamental Research Funds for the central universities(No.2023CDJXY-018).
文摘AZ31/Mg3Y composites with a layer thickness of 100-200μm were fabricated by accumulated rolling bonding(ARB),which was followed by diffusion annealing at 300℃ for 0-32 h.An interface layer,containing numerous Al-Y precipitates,is formed in the Mg3Y layer that is adjacent to the interface as a result of Al diffusing from the AZ31 layers into the Mg3Y layers.The thickness of the interface layer gets increased and more precipitates are formed in the interface layer with the extension of the annealing time.The microhardness of the AZ31 and Mg3Y layer decreases firstly and then reaches a stable value,while the microhardness of the interface layer increases gradually with the extension of the annealing time.The AZ31/Mg3Y composites exhibit equivalent strength but increased ductility after diffusion annealing,in comparison to the as-rolled AZ31/Mg3Y composite.In addition,the AZ31/Mg3Y composites after annealing always present higher strength and ductility than AZ31/AZ31 composite,which was fabricated by the same process as that for the AZ31/Mg3Y composites.Hetero-deformation induced strengthening also plays an important role in the excellent strength and ductility of the annealed AZ31/Mg3Y composite.This study can provide a direction for improving the plasticity and strength of magnesium alloys synergistically.
基金the National Natural Science Foundation of China(41901079)Open Fund of State Key Laboratory of Frozen Soil Engineering(SKLFSE202120)+1 种基金the Independent Research Project of State Key Laboratory of Frozen Soil Engineering(SKLFSE-ZT-202209)Hongliu Excellent Youth Project of Lanzhou University of Technology(062006)。
文摘In cold regions,the thermal effect of accumulated water on underlying permafrost and permafrost subgrade remains a significant hazard causing engineering risks.Water depth of accumulated water may be an important influence factor of permafrost thermal stability,but there is lack of qualitative and quantitative research about that.In this study,equivalent thermal conductivity theory and solid heat transfer theory have been used to establish the calculation model for simulating heat transfer in water and soil.Thereafter,the accuracy and reliability of the calculation model are checked by monitored data and subsequently used to analyze the thermal erosion of water on underlying permafrost and permafrost under the embankment.These simulation results show that shallow water can protect permafrost and deeper water disrupts the thermal stability of underlying permafrost.The thermal effect extent of water is primarily determined by its depth,and the concept of critical depth and stable depth of accumulated water has been proposed.Moreover,the temperature field of permafrost under embankment can be changed by the slope toe water.In addition,the thermal effect range of the slope toe water is limited by the thermal influence radius,which increases with the depth of standing water.These findings provide support as well as a fundamental base for environmental issues arising from the accumulated water.These observations will,thus,also be valuable to further engineering environment studies in cold regions.
