This paper utilizes the Theil and decoupling indices to analyze variation in carbon productivity as well as the factors that influence regional carbon productivity in China and proposes carbon emission reduction count...This paper utilizes the Theil and decoupling indices to analyze variation in carbon productivity as well as the factors that influence regional carbon productivity in China and proposes carbon emission reduction countermeasures. The authors conclude that most provinces exhibit year-on-year rising carbon productivity, a trend which decreases moving from east to western China. When applied to carbon productivity, the Theil index presents distinct regional differences. Moreover, the regional variance in carbon productivity is consistently reduced in eastern China and becomes smaller in central China. The difference, however, grows in western China. Carbon productivity grows with the highest speed in central China and the lowest speed in western China. Overall variation in carbon productivity mainly arises from intra-regional difference, whereas inter-regional difference mainly contributed by eastern China. In recent years; both the decoupling index, a dynamic value equal to the rate of change rate in carbon emissions divided by the rate of change in GDP during a given period of time, and carbon productivity vary in different economic development stages. Even if under the same decoupling state, carbon productivity remains different in three regions, i.e., that of the eastern region is higher than the other two regions .展开更多
The agricultural and land policies in China are always focused on protecting its food supply and security because of the country's large population and improved diets. The crop production guide 'Take Grain as the Ke...The agricultural and land policies in China are always focused on protecting its food supply and security because of the country's large population and improved diets. The crop production guide 'Take Grain as the Key Link prompted peasants to plant grain on most of the agricultural land, leading to the majority of fertilizer being used in grain crops for many years in China. This situation has changed dramatically in recent years. Based on data pertaining to provincial crops sown area and fertilizer use per unit area in 1998 and 2008, the temporal and spatial variations of China's fertilizer consumption by crops were analyzed at the provincial level, and the results are presented here. (1) Fertilizer consumption in China grew strongly in the last decade, while the growth was mainly attributable to the increase of fertilizer consumption by horticultural crops. The fertilizer consumption of grain crops dropped from 71.0% in 1998 to 57.8% in 2008. Thus, it is concluded that the emphasis of fertilizer consumption is shifting toward horticultural crops. (2) There were marked differences in the growth rates of fertilizer consumption from the regional point of view. The national average growth rate of fertilizer consumption was 31.9% during 1998-2008. The western and northeastern parts of the country came close to the national average, while the eastern part was lower, with an average of 13.0%, and central China was much higher (50.8%). The increase of fertilizer consumption in central and west China was higher than the other zones, which already accounted for 77.9% of the national total. Thus, it is concluded that the consumption emphasis of chemical fertilizer shifts toward the central and western regions. (3) The decline of fertilizer consumption by grain crops was largely due to the decrease in sown area compared with the increase by vegetable crops attributable to the enlarging sown area; the increase by orchard crops was affected by both expanding the sown area and fertilizer use per unit area.展开更多
BACKGROUND Incidence of cholangiocarcinoma(CCA)is rising,with overall prognosis remaining very poor.Reasons for the high mortality of CCA include its late presentation in most patients,when curative options are no lon...BACKGROUND Incidence of cholangiocarcinoma(CCA)is rising,with overall prognosis remaining very poor.Reasons for the high mortality of CCA include its late presentation in most patients,when curative options are no longer feasible,and poor response to systemic therapies for advanced disease.Late presentation presents a large barrier to improving outcomes and is often associated with diagnosis via mergency presentation(EP).Earlier diagnoses may be made by Two Week Wait(TWW)referrals through General practitioner(GP).We hypothesise that TWW referrals and EP routes to diagnosis differ across regions in England.AIM To investigate routes to diagnosis of CCA over time,regional variation and influencing factors.METHODS We linked patient records from the National Cancer Registration Dataset to Hospital Episode Statistics,Cancer Waiting Times and Cancer Screening Programme datasets to define routes to diagnosis and certain patient characteristics for patients diagnosed 2006-2017 in England.We used linear probability models to investigate geographic variation by assessing the proportions of patients diagnosed via TWW referral or EP across Cancer Alliances in England,adjusting for potential confounders.Correlation between the proportion of people diagnosed by TWW referral and EP was investigated with Spearman’s correlation coefficient.RESULTS Of 23632 patients diagnosed between 2006-2017 in England,the most common route to diagnosis was EP(49.6%).Non-TWW GP referrals accounted for 20.5%of diagnosis routes,13.8%were diagnosed by TWW referral,and the remainder 16.2%were diagnosed via an‘other’or Unknown route.The proportion diagnosed via a TWW referral doubled between 2006-2017 rising from 9.9%to 19.8%,conversely EP diagnosis route declined,falling from 51.3%to 46.0%.Statistically significant variation in both the TWW referral and EP proportions was found across Cancer Alliances.Age,presence of comorbidity and underlying liver disease were independently associated with both a lower proportion of patients diagnosed via TWW referral,and a higher proportion diagnosed by EP after adjusting for other potential confounders.CONCLUSION There is significant geographic and socio-demographic variation in routes to diagnosis of CCA in England.Knowledge sharing of best practice may improve diagnostic pathways and reduce unwarranted variation.展开更多
Aimed at improving knowledge regarding the diurnal cycle of warm-season rainfall in northwestern China,this study investigated the diurnal variations of warm-season precipitation with different durations in Xinjiang,C...Aimed at improving knowledge regarding the diurnal cycle of warm-season rainfall in northwestern China,this study investigated the diurnal variations of warm-season precipitation with different durations in Xinjiang,China,using an hourly gauge–satellite merged precipitation product during 2008 to 2019.Results show noticeable diurnal variations with distinctive regional features.The primary peak is in the early evening.Rainfall events with duration less than 3 h occur more often across the whole of Xinjiang and contribute more than half of the precipitation amount over its northern and southern peripheries,while rainfall events with duration more than 7 h over the Tianshan Mountains are responsible for the primary peak in the diurnal variations of warm-season precipitation.展开更多
BACKGROUND Incidence and severity variations of inflammatory bowel disease(IBD)have been reported from Western populations between continents and regions of the same countries.However,no data were available from other...BACKGROUND Incidence and severity variations of inflammatory bowel disease(IBD)have been reported from Western populations between continents and regions of the same countries.However,no data were available from other countries.AIM To investigate the regional differences in the IBD profiles of pediatric patients from the Kingdom of Saudi Arabia.METHODS Data from a national multicenter IBD study were used.The incidence,time trend,and clinical presentation of Crohn’s disease(CD)and ulcerative colitis(UC)in the Central region(CR),Western region(WR),and Eastern region(ER)were analyzed and compared.Statistical analysis included Poisson regression analysis for incidence variation and Chi-square test for demographic and clinical parameters.A P<0.05 was considered significant.RESULTS The prevalence of positive family history was lower in children with CD from the ER than the CR or the WR.Consanguinity rate was higher in children with CD and UC from the CR and the ER,respectively.The incidences and time trends of CD and UC were not significantly different between regions.In the ER,a significantly higher percentage of children with CD presented with abdominal pain(P<0.001),blood in stools(P=0.048),stricturing or penetrating disease(P=0.029),higher erythrocyte sedimentation rate(P<0.001),higher C-reactive protein(P<0.001),higher anemia(P=0.017),and lower albumin level(P=0.014).For children with UC from the ER,a significantly higher percentage presented with anemia(P=0.006)and a lower percentage with pancolitis(P<0.001).CONCLUSION The most important finding is the identification of significantly more severe presentation of CD in the ER of the Kingdom of Saudi Arabia.Prospective studies are needed to explain such variations.展开更多
Sea ice conditions in the Bohai Sea of China are sensitive to large-scale climatic variations. On the basis of CLARA-A1-SAL data, the albedo variations are examined in space and time in the winter(December, January a...Sea ice conditions in the Bohai Sea of China are sensitive to large-scale climatic variations. On the basis of CLARA-A1-SAL data, the albedo variations are examined in space and time in the winter(December, January and February) from 1992 to 2008 in the Bohai Sea sea ice region. Time series data of the sea ice concentration(SIC), the sea ice extent(SIE) and the sea surface temperature(SST) are used to analyze their relationship with the albedo. The sea ice albedo changed in volatility appears along with time, the trend is not obvious and increases very slightly during the study period at a rate of 0.388% per decade over the Bohai Sea sea ice region.The interannual variation is between 9.93% and 14.50%, and the average albedo is 11.79%. The sea ice albedo in years with heavy sea ice coverage, 1999, 2000 and 2005, is significantly higher than that in other years; in years with light sea ice coverage, 1994, 1998, 2001 and 2006, has low values. For the monthly albedo, the increasing trend(at a rate of 0.988% per decade) in December is distinctly higher than that in January and February. The mean albedo in January(12.90%) is also distinctly higher than that in the other two months. The albedo is significantly positively correlated with the SIC and is significantly negatively correlated with the SST(significance level 90%).展开更多
The purpose of the paper is to examine how the relationship between small and medium sized enterprises (SMEs) and their auditor varies between regions. Auditing literature, regional, and network studies are used to ...The purpose of the paper is to examine how the relationship between small and medium sized enterprises (SMEs) and their auditor varies between regions. Auditing literature, regional, and network studies are used to set up hypotheses on differences between rural regions and the metropolitan urban region. Survey data from 421 SMEs are analyzed and findings support that in rural regions, especially those with a strong entrepreneurial culture and tight inter-organizational links, the SME-auditor relationship is to a larger extent trust-based compared to the urban region. In the rural region, the auditor assumes the role as a business support agent providing valuable strategic advice. The SME-auditor relationship is weakest in the urban region where the auditor's role is limited.展开更多
This study aimed at investigating the influence of different growing conditions in two regions, Timbilil and Kangaita, on the levels of catechins and caffeine. Fresh leaf samples of 60 clones cultivated in both sites ...This study aimed at investigating the influence of different growing conditions in two regions, Timbilil and Kangaita, on the levels of catechins and caffeine. Fresh leaf samples of 60 clones cultivated in both sites were obtained, processed and assayed for levels of caffeine, total and individual catechins using Reverse Phase High Performance Liquid Chromatography (RP-HPLC). The obtained data was subjected to analysis of variance using GENSTAT-C statistical software. Safe for a few clones in the Kangaita site had significantly higher total and individual catechins than those grown in the Timbilil site. A mean epigallocatechin gallate (EGCG) content of 7.9% was observed for Kangaita clones compared to 6.7% in Timbilil. A similar trend was observed for the rest of the individual catechin fractions with a mean epicatechin gallate (ECG) of 3.3% in Kangaita and 2.5% in Timbilil, a mean epigallocatechin (EGC) of 5.2% in Kangaita compared to 5.0% in Timbilil and a mean epicatechin (EC) content of 1.5% in Kangaita compared to 1.4% in Timbilil. Similarly in the total catechins analyses, clones in Kangaita had a mean value of 18.7% compared to 16.2% observed for the Timbilil site clones. However, the Timbilil site clones had significantly high caffeine contents (mean, 4.2%) compared to the Kangaita site clones (mean, 3.9%) although with a few exceptions. Significant interactions (P < 0.05) between clone and region are also observed, suggesting that levels of these biomolecules are bound to differ with the growing region but the extent of variation will vary depending on the clonal genotype. The observed differences in levels of these biologically important biomolecules among the two regions shows the importance of the underlying conditions on the production of tea.展开更多
The aim of this study was to better understand the mechanisms of regional climate variation in mountain ranges with contrasting aspects as mediated by changes in global climate. It may help predict trends of vegetatio...The aim of this study was to better understand the mechanisms of regional climate variation in mountain ranges with contrasting aspects as mediated by changes in global climate. It may help predict trends of vegetation variations in native ecosystems in natural reserves. As measures of climate response, temperature and precipitation data from the north, east, and south-facing mountain ranges of Shennongjia Massif in the coldest and hottest months(January and July), different seasons(spring, summer, autumn, and winter) and each year were analyzed from a long-term dataset(1960 to 2003) to tested variations characteristics, temporal and spatial quantitative relationships of climates. The results showed that the average seasonal temperatures and precipitation in the north, east, and south aspects of the mountain ranges changed at different rates. The average seasonal temperatures change rate ranges in the north, east, and south-facing mountain ranges were from –0.0210℃/yr to 0.0143℃/yr, –0.0166℃/yr to 0.0311℃/yr, and –0.0290 ℃/yr to 0.0084℃/yr, respectively, and seasonal precipitation variation magnitude were from –1.4940 mm/yr to 0.6217 mm/yr, –1.6833 mm/yr to 2.6182 mm/yr, and –0.8567 mm/yr to 1.4077 mm/yr, respectively. The climates variation trend among the three mountain ranges were different in magnitude and direction, showing a complicated change of the climates in mountain ranges and some inconsistency with general trends in global climate change. The climate variations were significantly different and positively correlated cross mountain ranges, revealing that aspects significantly affected on climate variations and these variations resulted from a larger air circulation system, which were sensitive to global climate change. We conclude that location and terrain of aspect are the main factors affecting differences in climate variation among the mountain ranges with contrasting aspects.展开更多
Desertification is one of the most serious eco-environmental problems around Qinghai Lake.Based on GIS and RS,GIS analysis was used to obtain the information of spatial-temporal change and different pattern of deserti...Desertification is one of the most serious eco-environmental problems around Qinghai Lake.Based on GIS and RS,GIS analysis was used to obtain the information of spatial-temporal change and different pattern of desertification in each county around Qinghai Lake in four phases of1976,1987,1995 and 2006.Using the function of intersect and overlay supported by ARCGIS,with analyzing attributes of vector RS images,we obtained transition data and established transfer matrix of land-use types in recent 30 years,besides,protracted land-use transition maps of all desertification classes.In further,we analyzed transition quantity and direction of desertification in each county,moreover,reconstructed the process of spatial-temporal evolution of desertification.The results are showed below:(1)it's the transition between desertified land and others but not in the desertified that played the main role in Gangcha and Gonghe County,while the transfer between desertified lands were greater than that with other land-use types in Haiyan County.(2)Extremely severe desertified land mainly distributes in Ketu and Sand Islands that belongs to Haiyan County,and moderate desertified land in riversides of Gangcha County,also,the light desertification expanded too rapidly to become the most desertified land-use type in the surrounding of Qinghai Lake since 1976.(3)By using relative change rate of desertified land,the regional variability rank from top to toe was Gangcha,Haiyan and Gonghe.展开更多
This study has examined the temporal variation in monthly, seasonal & annual precipitation over the Western Himalayan Region(WHR) and the influence of global teleconnections, like the North Atlantic Oscillation(NA...This study has examined the temporal variation in monthly, seasonal & annual precipitation over the Western Himalayan Region(WHR) and the influence of global teleconnections, like the North Atlantic Oscillation(NAO) and Southern Oscillation(SO) Indices on seasonal & annual precipitation. The Mann–Kendall non-parametric test is applied for trend detection and the Pettitt–Mann–Whitney test is used to detect possible shift. Maximum entropy spectral analysis is applied to find the periodicity in annual & seasonal precipitation. The study shows a non-significant decreasing trend in annual precipitation over WHR for the period 1857-2006. However, in seasonal precipitation, a significant decreasing trend is observed in monsoon and a significant increasing trend in post-monsoon season during the same period. The significant decrease in monsoon precipitation may be due to weakening of its teleconnection with NAO as well as SO Indices mainly during last three decades. It is observed that the probable change of year in annual & monsoon precipitation over WHR is 1979. The study also shows significant periodicities of 2.3-2.9 years and of 3.9-4.7 years in annual & seasonal precipitation over WHR.展开更多
Dear Editor,We have read and reviewed the article entitled"The diurnal variation pattern of choroidal thickness in macular region of young healthy female individuals using spectral domain optical coherence tomography...Dear Editor,We have read and reviewed the article entitled"The diurnal variation pattern of choroidal thickness in macular region of young healthy female individuals using spectral domain optical coherence tomography"by Zhao et al^([1])with great interest.展开更多
Regional variations in acute coronary syndrome(ACS) management and outcomes have been an enormous public health issue. However, studies have yet to explore how to reduce the variations. The National Chest Pain Center ...Regional variations in acute coronary syndrome(ACS) management and outcomes have been an enormous public health issue. However, studies have yet to explore how to reduce the variations. The National Chest Pain Center Program(NCPCP) is the first nationwide, hospital-based, comprehensive, continuous quality improvement program for improving the quality of care in patients with ACS in China. We evaluated the association of NCPCP and regional variations in ACS healthcare using generalized linear mixed models and interaction analysis. Patients in the Western region had longer onset-to-first medical contact(FMC) time and time stay in non-percutaneous coronary intervention(PCI) hospitals, lower rates of PCI for ST-elevation myocardial infarction(STEMI) patients, and higher rates of medication usage.Patients in Central regions had relatively lower in-hospital mortality and in-hospital heart failure rates.Differences in the door-to-balloon time(Dto B) and in-hospital mortality between Western and Eastern regions were less after accreditation(β =-8.82, 95% confidence interval(CI)-14.61 to-3.03;OR = 0.79, 95%CI 0.70 to 0.91). Similar results were found in differences in Dto B time, primary PCI rate for STEMI between Central and Eastern regions. The differences in PCI for higher-risk non-ST-segment elevation acute coronary syndrome(NSTE-ACS) patients among different regions had been smaller.Additionally, the differences in medication use between Eastern and Western regions were higher after accreditation. Regional variations remained high in this large cohort of patients with ACS from hospitals participating in the NCPCP in China. More comprehensive interventions and hospital internal system optimizations are needed to further reduce regional variations in the management and outcomes of patients with ACS.展开更多
This paper presents and tests a series of sources of regional variations in self-employment rate in China in the 2000s, and illustrates that the stage of economic development is a major explanation for the variations ...This paper presents and tests a series of sources of regional variations in self-employment rate in China in the 2000s, and illustrates that the stage of economic development is a major explanation for the variations of self-employment rate across regions over the past decade. The negative relationship between the stage of economic development and self-employment rate identified in the paper indicates that China has entered the process offast industrialization, and self-employment is playing a diminishing role in economic growth and employment. We also find a substitution effect between self-employment and private enterprises. While both are important components of China 's private sector, private enterprises are becoming an increasingly important source of China's economic growth and employment. Furthermore, our findings also imply that when job opportunities are limited, self-employment in China is likely a forced choice of disadvantaged people who are not qualified for wage jobs.展开更多
Flood is one of the severest natural disasters in the world and has caused enormous causalities and property losses.Previous studies usually focus on flood magnitude and occurrence time at event scale,which are insuff...Flood is one of the severest natural disasters in the world and has caused enormous causalities and property losses.Previous studies usually focus on flood magnitude and occurrence time at event scale,which are insufficient to contain entire behavior characteristics of flood events.In our study,nine behavior metrics in five categories(e.g.,magnitude,duration,timing,rates of changes and variability)are adopted to fully describe a flood event.Regional and interannual variations of representative flood classes are investigated based on behavior similarity classification of numerous events.Contributions of geography,land use,hydrometeorology and human regulation on these variations are explored by rank analysis method.Results show that:five representative classes are identified,namely,conventional events(Class 1,61.7% of the total),low discharge events with multiple peaks(Class 2,5.3%),low discharge events with low rates of changes(Class 3,18.1%),low discharge events with high rates of changes(Class 4,10.8%)and high discharge events with long durations(Class 5,4.1%).Classes 1 and 3 are the major flood events and distributed across the whole region.Class 4 is mainly distributed in river sources,while Classes 2 and 5 are in the middle and down streams.Moreover,the flood class is most diverse in normal precipitation years(2006,2008-2010 and 2015),followed by wet years(2007,2013-2014),and dry years(2011 and 2012).All the impact factor categories explain 34.0%-84.1% of individual flood class variations.The hydrometeorological category(7.2%-56.9%)is the most important,followed by geographical(1.0%-6.3%),regulation(1.7%-5.1%)and land use(0.9%-2.2%)categories.This study could provide new insights into flood event variations in a comprehensive manner,and provide decision-making basis for flood control and resource utilization at basin scale.展开更多
The characteristics of water-soluble ions in size-resolved particulate matter were investigated usingion chromatography at Shangdianzi, a regional background station of Beijing, Tianjin, and Hebei. Seasonal total conc...The characteristics of water-soluble ions in size-resolved particulate matter were investigated usingion chromatography at Shangdianzi, a regional background station of Beijing, Tianjin, and Hebei. Seasonal total concentrations of ions (Na+, Mg2+, IC, Ca2+, NH+4, Cl-, SO2-4 and NO-3) were 75.5 ± 52.9 μg/m3 in spring, 26.5 ± 12.3 Bg/m3 in summer, 22.7 ± 20.4 μg/m3 in autumn, and 31.1 ± 23.9 μg/m3 in winter, respectively. The secondary ions (NO3, SO2-4 and NH+4), mainly associated with fine particles, accounted for 84.2% in spring, 82.1% in summer, 81.5% in autumn and 76.3% in winter of all ions. Strong correlations were found between NH+4 and SO2-4 (r = 0.95, p 〈 0.01) as well as NH+4 and NO-3 (r = 0.90, p 〈 0.01) in fine particles; while in coarse particles, correlations between Mg2+ and NO-3 (r = 0.80, p 〈 0.01), and Ca2+ and NO2+ (r = 0.85, p 〈 0.01) were found. The concentrations of Na+, IC, Mg2+, Ca2+, NH+4, Cl-, NO3, and SC2-4 were 2.02, 0.81, 0.36, 1.65, 9.58, 4.01, 18.9, and 18.4 μg/m3 in particulate matter from southeast-derived air masses, which were typically 1.58-3.37 times higher than in northwest trajectories. Thus, concentrations of water-soluble ions at this background station were heavily influenced by regional transport of serious pollution derived from biomass burning, coal combustion, industrial and vehicle exhaust emissions from Beijing, Tianjin, and Hebei.展开更多
The frost-free period(FFP)first frost date(FFD) and last frost date(LFD) have been regard as the important climate variables for agricultural production. Understanding the spatio-temporal variations of the FFPFF...The frost-free period(FFP)first frost date(FFD) and last frost date(LFD) have been regard as the important climate variables for agricultural production. Understanding the spatio-temporal variations of the FFPFFD and LFD is beneficial to reduce the harmful impacts of climate change on agricultural production and enhance the agricultural adaptation. This study examined daily minimum temperatures for 823 national-level meteorological stationscalculated the values of FFDLFD and FFP for station-specific and region-specific from 1951 to 2012estimated the gradients of linear regression for station-specific moving averages of FFDLFD and FFPand assessed station-specific time series of FFP and detected the abrupt change. The results as follows: at both the station level and the regional levelthe FFP across China decreases with the increase of latitude from south to northand with the increase of altitude from east to west generally. At the station levelthe inter-annual fluctuations of FFDLFD and FFP in south and west agricultural regions are greater than those in north and east. At the regional levelexcluding the QT regiontemporal changes of FFP are relatively small in both the low-latitude and the high-latitude regionsbut for the mid-latitude regions. According to the linear trend gradients of the moving average values of station-specific FFDLFD and FFPFFD was delayedLFD advancedand FFP extended gradually over the 80% of China. Furthermorethe change magnitudes for FFDLFD and FFP in the north and east agricultural regions are higher than that in the southern and western. Among the 659 station-specific time series of FFP examined by the Mann-Kendall test341 stationslocated mainly in the north regionhave one identifiable and significant abrupt change. And at the 341 stations with identified abrupt changesmost(57%) abrupt changes occurred during 1991–2012followed by the periods of 1981–1990(28%)1971–1980(12%)and 1951–1970(3%). The spatio-temporal variations of FFDLFD and FFP would provide important guidance to agricultural practices.展开更多
As defined in a decree issued in the spring of 583,the three heads or sanzhang system,designed to be implemented chiefly in the old Northern Qi area in Shandong,basically followed the Northern Qi version of 564,with s...As defined in a decree issued in the spring of 583,the three heads or sanzhang system,designed to be implemented chiefly in the old Northern Qi area in Shandong,basically followed the Northern Qi version of 564,with slight modifications.With the setting up of a system of xiang heads(xiangzheng乡正)who would hear disputes among the common people,as recommended in Su Wei’s memorial of the same year,the judicial position of xiangzheng coexisted with the administrative positions of the three-heads(or two-heads)system.The xiangli(乡里)system announced in the edict of 589 targeted the territory previously under the Chen dynasty;it was basically a continuation of the xiangli system of rural control originally based on a Han dynasty model and followed since then in the south under the Eastern Jin and the Southern dynasties.With the reform of the bureaucratic system in 607,the xiangli system centered on xiangzheng and lizhang became the basic system of rural administration under the Sui dynasty.In the course of its design and creation,the system had to take into account the institutions already existing in the target area and the question of feasibility.Thus“inconsistency”or“regional variation”was built into the system.However,in actual practice there was a tendency toward convergence that led to uniformity of implementation.In Chinese history,the coexistence of regional variation and uniformity was a marked feature of the formation and implementation of different systems.展开更多
A numerical model of the bearing fault of a motor with a closed-slot rotor using the finite element method(FEM)is proposed.The rotor’s radial motion can be regarded as static eccentric at the defect time points and h...A numerical model of the bearing fault of a motor with a closed-slot rotor using the finite element method(FEM)is proposed.The rotor’s radial motion can be regarded as static eccentric at the defect time points and healthy at other time points.The frequency of the harmonic component is analyzed corresponding to bearing fault in stator current according to the radial movement of the motor shaft.Moreover,the relative permeability variation region is established to achieve the radial motion of the rotor with bearing fault.Firstly,the relative permeability variation region is established in the health and static eccentric models.Then,the defect time points are estimated and the static eccentricity model by transient field is analyzed.Finally,the relative permeability of the variable region in the static eccentric model is imported into the variable region of the health model at the defect time points.The simulation results show that the air gap flux density of the bearing fault model is different from that of the health model and static eccentric models.In addition,the stator current contains harmonic components of the bearing fault.The analysis results prove the applicability of the proposed model.展开更多
In this paper an experiment of human locomotion was carried out using a motion capture system to extract the human gait features. The modifiable key gait parameters affecting the dominant performance of biped robot wa...In this paper an experiment of human locomotion was carried out using a motion capture system to extract the human gait features. The modifiable key gait parameters affecting the dominant performance of biped robot walking were obtained from the extracted human gait features. Based on the modifiable key gait parameters and the Allowable Zero Moment Point (ZMP) Variation Region (AZR), we proposed an effective Bio-inspired Gait Planning (BGP) and control scheme for biped robot to- wards a given travel distance D. First, we construct an on-line Bio-inspired Gait Synthesis algorithm (BGSN) to generate a complete walking gait motion using the modifiable key gait parameters. Second, a Bio-inspired Gait Parameters Optimization algorithm (BGPO) is established to minimize the energy consumption of all actuators and guarantee biped robot walking with certain walking stability margin. Third, the necessary controllers for biped robot were introduced in briefly. Simulation and experiment results demonstrated the effectiveness of the proposed method, and the gait control system was implemented on DRC-XT humanoid robot.展开更多
文摘This paper utilizes the Theil and decoupling indices to analyze variation in carbon productivity as well as the factors that influence regional carbon productivity in China and proposes carbon emission reduction countermeasures. The authors conclude that most provinces exhibit year-on-year rising carbon productivity, a trend which decreases moving from east to western China. When applied to carbon productivity, the Theil index presents distinct regional differences. Moreover, the regional variance in carbon productivity is consistently reduced in eastern China and becomes smaller in central China. The difference, however, grows in western China. Carbon productivity grows with the highest speed in central China and the lowest speed in western China. Overall variation in carbon productivity mainly arises from intra-regional difference, whereas inter-regional difference mainly contributed by eastern China. In recent years; both the decoupling index, a dynamic value equal to the rate of change rate in carbon emissions divided by the rate of change in GDP during a given period of time, and carbon productivity vary in different economic development stages. Even if under the same decoupling state, carbon productivity remains different in three regions, i.e., that of the eastern region is higher than the other two regions .
基金Foundation: National Natural Science Foundation of China, No. 40971062 National Basic Research Program of China, No.2010CB950902+1 种基金 National Natural Science Foundation of China, No.41101085 No.41171079
文摘The agricultural and land policies in China are always focused on protecting its food supply and security because of the country's large population and improved diets. The crop production guide 'Take Grain as the Key Link prompted peasants to plant grain on most of the agricultural land, leading to the majority of fertilizer being used in grain crops for many years in China. This situation has changed dramatically in recent years. Based on data pertaining to provincial crops sown area and fertilizer use per unit area in 1998 and 2008, the temporal and spatial variations of China's fertilizer consumption by crops were analyzed at the provincial level, and the results are presented here. (1) Fertilizer consumption in China grew strongly in the last decade, while the growth was mainly attributable to the increase of fertilizer consumption by horticultural crops. The fertilizer consumption of grain crops dropped from 71.0% in 1998 to 57.8% in 2008. Thus, it is concluded that the emphasis of fertilizer consumption is shifting toward horticultural crops. (2) There were marked differences in the growth rates of fertilizer consumption from the regional point of view. The national average growth rate of fertilizer consumption was 31.9% during 1998-2008. The western and northeastern parts of the country came close to the national average, while the eastern part was lower, with an average of 13.0%, and central China was much higher (50.8%). The increase of fertilizer consumption in central and west China was higher than the other zones, which already accounted for 77.9% of the national total. Thus, it is concluded that the consumption emphasis of chemical fertilizer shifts toward the central and western regions. (3) The decline of fertilizer consumption by grain crops was largely due to the decrease in sown area compared with the increase by vegetable crops attributable to the enlarging sown area; the increase by orchard crops was affected by both expanding the sown area and fertilizer use per unit area.
文摘BACKGROUND Incidence of cholangiocarcinoma(CCA)is rising,with overall prognosis remaining very poor.Reasons for the high mortality of CCA include its late presentation in most patients,when curative options are no longer feasible,and poor response to systemic therapies for advanced disease.Late presentation presents a large barrier to improving outcomes and is often associated with diagnosis via mergency presentation(EP).Earlier diagnoses may be made by Two Week Wait(TWW)referrals through General practitioner(GP).We hypothesise that TWW referrals and EP routes to diagnosis differ across regions in England.AIM To investigate routes to diagnosis of CCA over time,regional variation and influencing factors.METHODS We linked patient records from the National Cancer Registration Dataset to Hospital Episode Statistics,Cancer Waiting Times and Cancer Screening Programme datasets to define routes to diagnosis and certain patient characteristics for patients diagnosed 2006-2017 in England.We used linear probability models to investigate geographic variation by assessing the proportions of patients diagnosed via TWW referral or EP across Cancer Alliances in England,adjusting for potential confounders.Correlation between the proportion of people diagnosed by TWW referral and EP was investigated with Spearman’s correlation coefficient.RESULTS Of 23632 patients diagnosed between 2006-2017 in England,the most common route to diagnosis was EP(49.6%).Non-TWW GP referrals accounted for 20.5%of diagnosis routes,13.8%were diagnosed by TWW referral,and the remainder 16.2%were diagnosed via an‘other’or Unknown route.The proportion diagnosed via a TWW referral doubled between 2006-2017 rising from 9.9%to 19.8%,conversely EP diagnosis route declined,falling from 51.3%to 46.0%.Statistically significant variation in both the TWW referral and EP proportions was found across Cancer Alliances.Age,presence of comorbidity and underlying liver disease were independently associated with both a lower proportion of patients diagnosed via TWW referral,and a higher proportion diagnosed by EP after adjusting for other potential confounders.CONCLUSION There is significant geographic and socio-demographic variation in routes to diagnosis of CCA in England.Knowledge sharing of best practice may improve diagnostic pathways and reduce unwarranted variation.
基金supported by the National Key Research and Development Project of China[Grant Nos.2018YFC1507104 and 2018YFC1507603]the National Natural Science Foundation of China[Grants Nos.91937301,41875074,and 41675060]the National Key Scientific and Technological Infrastructure Project“Earth Lab”。
文摘Aimed at improving knowledge regarding the diurnal cycle of warm-season rainfall in northwestern China,this study investigated the diurnal variations of warm-season precipitation with different durations in Xinjiang,China,using an hourly gauge–satellite merged precipitation product during 2008 to 2019.Results show noticeable diurnal variations with distinctive regional features.The primary peak is in the early evening.Rainfall events with duration less than 3 h occur more often across the whole of Xinjiang and contribute more than half of the precipitation amount over its northern and southern peripheries,while rainfall events with duration more than 7 h over the Tianshan Mountains are responsible for the primary peak in the diurnal variations of warm-season precipitation.
基金Supported by the Deanship for Scientific Research,King Saud University,Riyadh,Kingdom of Saudi Arabia,No.RGP-1436-007
文摘BACKGROUND Incidence and severity variations of inflammatory bowel disease(IBD)have been reported from Western populations between continents and regions of the same countries.However,no data were available from other countries.AIM To investigate the regional differences in the IBD profiles of pediatric patients from the Kingdom of Saudi Arabia.METHODS Data from a national multicenter IBD study were used.The incidence,time trend,and clinical presentation of Crohn’s disease(CD)and ulcerative colitis(UC)in the Central region(CR),Western region(WR),and Eastern region(ER)were analyzed and compared.Statistical analysis included Poisson regression analysis for incidence variation and Chi-square test for demographic and clinical parameters.A P<0.05 was considered significant.RESULTS The prevalence of positive family history was lower in children with CD from the ER than the CR or the WR.Consanguinity rate was higher in children with CD and UC from the CR and the ER,respectively.The incidences and time trends of CD and UC were not significantly different between regions.In the ER,a significantly higher percentage of children with CD presented with abdominal pain(P<0.001),blood in stools(P=0.048),stricturing or penetrating disease(P=0.029),higher erythrocyte sedimentation rate(P<0.001),higher C-reactive protein(P<0.001),higher anemia(P=0.017),and lower albumin level(P=0.014).For children with UC from the ER,a significantly higher percentage presented with anemia(P=0.006)and a lower percentage with pancolitis(P<0.001).CONCLUSION The most important finding is the identification of significantly more severe presentation of CD in the ER of the Kingdom of Saudi Arabia.Prospective studies are needed to explain such variations.
文摘Sea ice conditions in the Bohai Sea of China are sensitive to large-scale climatic variations. On the basis of CLARA-A1-SAL data, the albedo variations are examined in space and time in the winter(December, January and February) from 1992 to 2008 in the Bohai Sea sea ice region. Time series data of the sea ice concentration(SIC), the sea ice extent(SIE) and the sea surface temperature(SST) are used to analyze their relationship with the albedo. The sea ice albedo changed in volatility appears along with time, the trend is not obvious and increases very slightly during the study period at a rate of 0.388% per decade over the Bohai Sea sea ice region.The interannual variation is between 9.93% and 14.50%, and the average albedo is 11.79%. The sea ice albedo in years with heavy sea ice coverage, 1999, 2000 and 2005, is significantly higher than that in other years; in years with light sea ice coverage, 1994, 1998, 2001 and 2006, has low values. For the monthly albedo, the increasing trend(at a rate of 0.988% per decade) in December is distinctly higher than that in January and February. The mean albedo in January(12.90%) is also distinctly higher than that in the other two months. The albedo is significantly positively correlated with the SIC and is significantly negatively correlated with the SST(significance level 90%).
文摘The purpose of the paper is to examine how the relationship between small and medium sized enterprises (SMEs) and their auditor varies between regions. Auditing literature, regional, and network studies are used to set up hypotheses on differences between rural regions and the metropolitan urban region. Survey data from 421 SMEs are analyzed and findings support that in rural regions, especially those with a strong entrepreneurial culture and tight inter-organizational links, the SME-auditor relationship is to a larger extent trust-based compared to the urban region. In the rural region, the auditor assumes the role as a business support agent providing valuable strategic advice. The SME-auditor relationship is weakest in the urban region where the auditor's role is limited.
文摘This study aimed at investigating the influence of different growing conditions in two regions, Timbilil and Kangaita, on the levels of catechins and caffeine. Fresh leaf samples of 60 clones cultivated in both sites were obtained, processed and assayed for levels of caffeine, total and individual catechins using Reverse Phase High Performance Liquid Chromatography (RP-HPLC). The obtained data was subjected to analysis of variance using GENSTAT-C statistical software. Safe for a few clones in the Kangaita site had significantly higher total and individual catechins than those grown in the Timbilil site. A mean epigallocatechin gallate (EGCG) content of 7.9% was observed for Kangaita clones compared to 6.7% in Timbilil. A similar trend was observed for the rest of the individual catechin fractions with a mean epicatechin gallate (ECG) of 3.3% in Kangaita and 2.5% in Timbilil, a mean epigallocatechin (EGC) of 5.2% in Kangaita compared to 5.0% in Timbilil and a mean epicatechin (EC) content of 1.5% in Kangaita compared to 1.4% in Timbilil. Similarly in the total catechins analyses, clones in Kangaita had a mean value of 18.7% compared to 16.2% observed for the Timbilil site clones. However, the Timbilil site clones had significantly high caffeine contents (mean, 4.2%) compared to the Kangaita site clones (mean, 3.9%) although with a few exceptions. Significant interactions (P < 0.05) between clone and region are also observed, suggesting that levels of these biomolecules are bound to differ with the growing region but the extent of variation will vary depending on the clonal genotype. The observed differences in levels of these biologically important biomolecules among the two regions shows the importance of the underlying conditions on the production of tea.
基金Under the auspices of National Natural Science Foundation of China(No.41371216)Natural Science Foundation of Hubei Province(No.2014CFB376)
文摘The aim of this study was to better understand the mechanisms of regional climate variation in mountain ranges with contrasting aspects as mediated by changes in global climate. It may help predict trends of vegetation variations in native ecosystems in natural reserves. As measures of climate response, temperature and precipitation data from the north, east, and south-facing mountain ranges of Shennongjia Massif in the coldest and hottest months(January and July), different seasons(spring, summer, autumn, and winter) and each year were analyzed from a long-term dataset(1960 to 2003) to tested variations characteristics, temporal and spatial quantitative relationships of climates. The results showed that the average seasonal temperatures and precipitation in the north, east, and south aspects of the mountain ranges changed at different rates. The average seasonal temperatures change rate ranges in the north, east, and south-facing mountain ranges were from –0.0210℃/yr to 0.0143℃/yr, –0.0166℃/yr to 0.0311℃/yr, and –0.0290 ℃/yr to 0.0084℃/yr, respectively, and seasonal precipitation variation magnitude were from –1.4940 mm/yr to 0.6217 mm/yr, –1.6833 mm/yr to 2.6182 mm/yr, and –0.8567 mm/yr to 1.4077 mm/yr, respectively. The climates variation trend among the three mountain ranges were different in magnitude and direction, showing a complicated change of the climates in mountain ranges and some inconsistency with general trends in global climate change. The climate variations were significantly different and positively correlated cross mountain ranges, revealing that aspects significantly affected on climate variations and these variations resulted from a larger air circulation system, which were sensitive to global climate change. We conclude that location and terrain of aspect are the main factors affecting differences in climate variation among the mountain ranges with contrasting aspects.
基金National Key Technology R&D Program of China(2007BAC30B03)"The Fundamental Research Funds for the Central Universities"and"Forestry Industry Research Special Funds for Public Welfare"(201004025)
文摘Desertification is one of the most serious eco-environmental problems around Qinghai Lake.Based on GIS and RS,GIS analysis was used to obtain the information of spatial-temporal change and different pattern of desertification in each county around Qinghai Lake in four phases of1976,1987,1995 and 2006.Using the function of intersect and overlay supported by ARCGIS,with analyzing attributes of vector RS images,we obtained transition data and established transfer matrix of land-use types in recent 30 years,besides,protracted land-use transition maps of all desertification classes.In further,we analyzed transition quantity and direction of desertification in each county,moreover,reconstructed the process of spatial-temporal evolution of desertification.The results are showed below:(1)it's the transition between desertified land and others but not in the desertified that played the main role in Gangcha and Gonghe County,while the transfer between desertified lands were greater than that with other land-use types in Haiyan County.(2)Extremely severe desertified land mainly distributes in Ketu and Sand Islands that belongs to Haiyan County,and moderate desertified land in riversides of Gangcha County,also,the light desertification expanded too rapidly to become the most desertified land-use type in the surrounding of Qinghai Lake since 1976.(3)By using relative change rate of desertified land,the regional variability rank from top to toe was Gangcha,Haiyan and Gonghe.
文摘This study has examined the temporal variation in monthly, seasonal & annual precipitation over the Western Himalayan Region(WHR) and the influence of global teleconnections, like the North Atlantic Oscillation(NAO) and Southern Oscillation(SO) Indices on seasonal & annual precipitation. The Mann–Kendall non-parametric test is applied for trend detection and the Pettitt–Mann–Whitney test is used to detect possible shift. Maximum entropy spectral analysis is applied to find the periodicity in annual & seasonal precipitation. The study shows a non-significant decreasing trend in annual precipitation over WHR for the period 1857-2006. However, in seasonal precipitation, a significant decreasing trend is observed in monsoon and a significant increasing trend in post-monsoon season during the same period. The significant decrease in monsoon precipitation may be due to weakening of its teleconnection with NAO as well as SO Indices mainly during last three decades. It is observed that the probable change of year in annual & monsoon precipitation over WHR is 1979. The study also shows significant periodicities of 2.3-2.9 years and of 3.9-4.7 years in annual & seasonal precipitation over WHR.
文摘Dear Editor,We have read and reviewed the article entitled"The diurnal variation pattern of choroidal thickness in macular region of young healthy female individuals using spectral domain optical coherence tomography"by Zhao et al^([1])with great interest.
基金supported by the 2020 China Medical Board(CMB) Competition Program (20-376)。
文摘Regional variations in acute coronary syndrome(ACS) management and outcomes have been an enormous public health issue. However, studies have yet to explore how to reduce the variations. The National Chest Pain Center Program(NCPCP) is the first nationwide, hospital-based, comprehensive, continuous quality improvement program for improving the quality of care in patients with ACS in China. We evaluated the association of NCPCP and regional variations in ACS healthcare using generalized linear mixed models and interaction analysis. Patients in the Western region had longer onset-to-first medical contact(FMC) time and time stay in non-percutaneous coronary intervention(PCI) hospitals, lower rates of PCI for ST-elevation myocardial infarction(STEMI) patients, and higher rates of medication usage.Patients in Central regions had relatively lower in-hospital mortality and in-hospital heart failure rates.Differences in the door-to-balloon time(Dto B) and in-hospital mortality between Western and Eastern regions were less after accreditation(β =-8.82, 95% confidence interval(CI)-14.61 to-3.03;OR = 0.79, 95%CI 0.70 to 0.91). Similar results were found in differences in Dto B time, primary PCI rate for STEMI between Central and Eastern regions. The differences in PCI for higher-risk non-ST-segment elevation acute coronary syndrome(NSTE-ACS) patients among different regions had been smaller.Additionally, the differences in medication use between Eastern and Western regions were higher after accreditation. Regional variations remained high in this large cohort of patients with ACS from hospitals participating in the NCPCP in China. More comprehensive interventions and hospital internal system optimizations are needed to further reduce regional variations in the management and outcomes of patients with ACS.
基金Sichuan University for providing research funding(No.SKX201030 and SKG201008)
文摘This paper presents and tests a series of sources of regional variations in self-employment rate in China in the 2000s, and illustrates that the stage of economic development is a major explanation for the variations of self-employment rate across regions over the past decade. The negative relationship between the stage of economic development and self-employment rate identified in the paper indicates that China has entered the process offast industrialization, and self-employment is playing a diminishing role in economic growth and employment. We also find a substitution effect between self-employment and private enterprises. While both are important components of China 's private sector, private enterprises are becoming an increasingly important source of China's economic growth and employment. Furthermore, our findings also imply that when job opportunities are limited, self-employment in China is likely a forced choice of disadvantaged people who are not qualified for wage jobs.
基金National Key Research and Development Program of China,No.2016YFC0400902National Natural Science Foundation of China,No.41671024,No.41807171。
文摘Flood is one of the severest natural disasters in the world and has caused enormous causalities and property losses.Previous studies usually focus on flood magnitude and occurrence time at event scale,which are insufficient to contain entire behavior characteristics of flood events.In our study,nine behavior metrics in five categories(e.g.,magnitude,duration,timing,rates of changes and variability)are adopted to fully describe a flood event.Regional and interannual variations of representative flood classes are investigated based on behavior similarity classification of numerous events.Contributions of geography,land use,hydrometeorology and human regulation on these variations are explored by rank analysis method.Results show that:five representative classes are identified,namely,conventional events(Class 1,61.7% of the total),low discharge events with multiple peaks(Class 2,5.3%),low discharge events with low rates of changes(Class 3,18.1%),low discharge events with high rates of changes(Class 4,10.8%)and high discharge events with long durations(Class 5,4.1%).Classes 1 and 3 are the major flood events and distributed across the whole region.Class 4 is mainly distributed in river sources,while Classes 2 and 5 are in the middle and down streams.Moreover,the flood class is most diverse in normal precipitation years(2006,2008-2010 and 2015),followed by wet years(2007,2013-2014),and dry years(2011 and 2012).All the impact factor categories explain 34.0%-84.1% of individual flood class variations.The hydrometeorological category(7.2%-56.9%)is the most important,followed by geographical(1.0%-6.3%),regulation(1.7%-5.1%)and land use(0.9%-2.2%)categories.This study could provide new insights into flood event variations in a comprehensive manner,and provide decision-making basis for flood control and resource utilization at basin scale.
基金supported by the National Environmental Protection Commonweal Research Project(No.201509062 and No.201409073)the National Natural Science Foundation of China(No.41105089)+1 种基金Research Project of Environmental Development Cenre(No.DY-2016-5)State Key Laboratory of Environmental Criteria and Risk Assessment,Chinese Research Academy of Environmental Sciences(No.SKLECRA201637)
文摘The characteristics of water-soluble ions in size-resolved particulate matter were investigated usingion chromatography at Shangdianzi, a regional background station of Beijing, Tianjin, and Hebei. Seasonal total concentrations of ions (Na+, Mg2+, IC, Ca2+, NH+4, Cl-, SO2-4 and NO-3) were 75.5 ± 52.9 μg/m3 in spring, 26.5 ± 12.3 Bg/m3 in summer, 22.7 ± 20.4 μg/m3 in autumn, and 31.1 ± 23.9 μg/m3 in winter, respectively. The secondary ions (NO3, SO2-4 and NH+4), mainly associated with fine particles, accounted for 84.2% in spring, 82.1% in summer, 81.5% in autumn and 76.3% in winter of all ions. Strong correlations were found between NH+4 and SO2-4 (r = 0.95, p 〈 0.01) as well as NH+4 and NO-3 (r = 0.90, p 〈 0.01) in fine particles; while in coarse particles, correlations between Mg2+ and NO-3 (r = 0.80, p 〈 0.01), and Ca2+ and NO2+ (r = 0.85, p 〈 0.01) were found. The concentrations of Na+, IC, Mg2+, Ca2+, NH+4, Cl-, NO3, and SC2-4 were 2.02, 0.81, 0.36, 1.65, 9.58, 4.01, 18.9, and 18.4 μg/m3 in particulate matter from southeast-derived air masses, which were typically 1.58-3.37 times higher than in northwest trajectories. Thus, concentrations of water-soluble ions at this background station were heavily influenced by regional transport of serious pollution derived from biomass burning, coal combustion, industrial and vehicle exhaust emissions from Beijing, Tianjin, and Hebei.
基金National Basic Program of China(973 Program),No.2012CB955800National Natural Science Foundation of China,No.41671536,No.41501588+1 种基金Qinghai Key Laboratory Open Fund of Disaster Prevention and Reduction,No.QHKF201401Key Scientific Research Projects in Colleges and Universities,No.17A170005
文摘The frost-free period(FFP)first frost date(FFD) and last frost date(LFD) have been regard as the important climate variables for agricultural production. Understanding the spatio-temporal variations of the FFPFFD and LFD is beneficial to reduce the harmful impacts of climate change on agricultural production and enhance the agricultural adaptation. This study examined daily minimum temperatures for 823 national-level meteorological stationscalculated the values of FFDLFD and FFP for station-specific and region-specific from 1951 to 2012estimated the gradients of linear regression for station-specific moving averages of FFDLFD and FFPand assessed station-specific time series of FFP and detected the abrupt change. The results as follows: at both the station level and the regional levelthe FFP across China decreases with the increase of latitude from south to northand with the increase of altitude from east to west generally. At the station levelthe inter-annual fluctuations of FFDLFD and FFP in south and west agricultural regions are greater than those in north and east. At the regional levelexcluding the QT regiontemporal changes of FFP are relatively small in both the low-latitude and the high-latitude regionsbut for the mid-latitude regions. According to the linear trend gradients of the moving average values of station-specific FFDLFD and FFPFFD was delayedLFD advancedand FFP extended gradually over the 80% of China. Furthermorethe change magnitudes for FFDLFD and FFP in the north and east agricultural regions are higher than that in the southern and western. Among the 659 station-specific time series of FFP examined by the Mann-Kendall test341 stationslocated mainly in the north regionhave one identifiable and significant abrupt change. And at the 341 stations with identified abrupt changesmost(57%) abrupt changes occurred during 1991–2012followed by the periods of 1981–1990(28%)1971–1980(12%)and 1951–1970(3%). The spatio-temporal variations of FFDLFD and FFP would provide important guidance to agricultural practices.
文摘As defined in a decree issued in the spring of 583,the three heads or sanzhang system,designed to be implemented chiefly in the old Northern Qi area in Shandong,basically followed the Northern Qi version of 564,with slight modifications.With the setting up of a system of xiang heads(xiangzheng乡正)who would hear disputes among the common people,as recommended in Su Wei’s memorial of the same year,the judicial position of xiangzheng coexisted with the administrative positions of the three-heads(or two-heads)system.The xiangli(乡里)system announced in the edict of 589 targeted the territory previously under the Chen dynasty;it was basically a continuation of the xiangli system of rural control originally based on a Han dynasty model and followed since then in the south under the Eastern Jin and the Southern dynasties.With the reform of the bureaucratic system in 607,the xiangli system centered on xiangzheng and lizhang became the basic system of rural administration under the Sui dynasty.In the course of its design and creation,the system had to take into account the institutions already existing in the target area and the question of feasibility.Thus“inconsistency”or“regional variation”was built into the system.However,in actual practice there was a tendency toward convergence that led to uniformity of implementation.In Chinese history,the coexistence of regional variation and uniformity was a marked feature of the formation and implementation of different systems.
基金Supported by the National Natural Science Foundation of China(51977055)Major Science and Technology Program of Anhui Province(201903a05020042)Anhui Province Key Laboratory of Large-scale Submersible Electric Pump and Accoutrements.
文摘A numerical model of the bearing fault of a motor with a closed-slot rotor using the finite element method(FEM)is proposed.The rotor’s radial motion can be regarded as static eccentric at the defect time points and healthy at other time points.The frequency of the harmonic component is analyzed corresponding to bearing fault in stator current according to the radial movement of the motor shaft.Moreover,the relative permeability variation region is established to achieve the radial motion of the rotor with bearing fault.Firstly,the relative permeability variation region is established in the health and static eccentric models.Then,the defect time points are estimated and the static eccentricity model by transient field is analyzed.Finally,the relative permeability of the variable region in the static eccentric model is imported into the variable region of the health model at the defect time points.The simulation results show that the air gap flux density of the bearing fault model is different from that of the health model and static eccentric models.In addition,the stator current contains harmonic components of the bearing fault.The analysis results prove the applicability of the proposed model.
基金Acknowledgment This research has been supported by Project of Science and Technology Support Plan of Jiangsu province (Grant No. BE2012057) and Science and Technology Support Plan Key Projects of Jiangsu province (Grant No. BE2013003) and National Nature Science Foundation of China (Grant No. 51405469).
文摘In this paper an experiment of human locomotion was carried out using a motion capture system to extract the human gait features. The modifiable key gait parameters affecting the dominant performance of biped robot walking were obtained from the extracted human gait features. Based on the modifiable key gait parameters and the Allowable Zero Moment Point (ZMP) Variation Region (AZR), we proposed an effective Bio-inspired Gait Planning (BGP) and control scheme for biped robot to- wards a given travel distance D. First, we construct an on-line Bio-inspired Gait Synthesis algorithm (BGSN) to generate a complete walking gait motion using the modifiable key gait parameters. Second, a Bio-inspired Gait Parameters Optimization algorithm (BGPO) is established to minimize the energy consumption of all actuators and guarantee biped robot walking with certain walking stability margin. Third, the necessary controllers for biped robot were introduced in briefly. Simulation and experiment results demonstrated the effectiveness of the proposed method, and the gait control system was implemented on DRC-XT humanoid robot.