Background: Maternal mortality remains a major public health problem worldwide. Objectives: Our study aims to present the results of an analysis of reviews of maternal deaths at HGOPY. Methodology: This was a descript...Background: Maternal mortality remains a major public health problem worldwide. Objectives: Our study aims to present the results of an analysis of reviews of maternal deaths at HGOPY. Methodology: This was a descriptive cross-sectional study with retrospective data collection from archived records and reviewed maternal death reports. Our study lasted 8 months, from October 1, 2023 to May 31, 2024. The study covered maternal death files at the HGOPY over an 8-year period, from 1st of January 2016 to the 31st of December 2023. Data were processed and analyzed using Statitical Paquage for Social Science (SPSS) version 26.0. Results: We counted a total of 160 maternal deaths, of which 97 had been reviewed. We excluded 61 deceased women reviewed and retained 33. We recorded a cumulative total of 160 maternal deaths and 19,651 live births. The peak in the proportion of maternal deaths at the Yaoundé Gynaeco-Obstetric and Paediatric Hospital was in 2021, with a proportion of 0.013. No maternal deaths had been reviewed between 2016 to 2017. Most deaths (64%) occurred between 37 and 40 weeks. The majority (30.5%) were aged between 30 and 35. The data show that 80.6% of maternal deaths were due to direct obstetric causes, while 19.4% were due to indirect causes. Most deaths (69.4%) were preventable. Only 8.3% were not preventable. Conclusion: Concerted efforts must be made to adapt maternal death prevention and management strategies to local contexts in order to significantly reduce these alarming figures.展开更多
The abundance of live and dead Oithona similis in Jiaozhou Bay,Shandong,China,was investigated monthly from December 2008 to November 2009 via the neutral red staining method.The annual variation in total abundance wa...The abundance of live and dead Oithona similis in Jiaozhou Bay,Shandong,China,was investigated monthly from December 2008 to November 2009 via the neutral red staining method.The annual variation in total abundance was similar for females,males,and copepodites,with a main numerical peak from February to July and a minor peak in November,but the variations in carcass abundance and death proportion were different.The monthly average abundance of male and copepodite carcasses significantly increased with their total abundance(P<0.001),whereas no such correlation was observed for females.The abundance of female carcasses peaked at 12.4 inds./m^(3) in November but remained below 3.0 inds./m^(3) in all other months.The monthly average death proportion ranged 0.3%-4.9% for females,3.6%-25.7% for males,and 2.6%-8.4% for copepodites.On average,the death proportion of males was 9.2 times greater than that of females and 3.5 times greater than that of copepodites.Therefore,significant sexual difference exists in the non-predatory mortality of O.similis and this difference is an important cause of the female-skewed sex ratios observed in the field.展开更多
The Loess Plateau region in China is characterized by a fragile environment,where vegetation is susceptible to both natural variations and anthropogenic influences.Previous research has indicated a greening trend in v...The Loess Plateau region in China is characterized by a fragile environment,where vegetation is susceptible to both natural variations and anthropogenic influences.Previous research has indicated a greening trend in vegetation across the Loess Plateau over the past two decades.However,the specific contributions of natural and anthropogenic drivers,both individually and interactively,to vegetation distribution remain unclear.To address this gap,we conducted a study using Shaanxi Province as a case area.Utilizing multisource data,we employed the Geographical Detector Model(GDM)to analyze the impacts of natural and human related factors on vegetation distribution.Our analysis revealed that the average NDVI(Normalized Difference Vegetation Index)increased at a rate of 0.006 per year from 2000 to 2021.Notably,88.8%of the region experienced vegetation greening,while 4.5%showed significant declines in NDVI,particularly in areas,such as Xi'an,Weinan,Baoji,Hanzhong,and Ankang.Furthermore,NDVI trend projections suggest that the area undergoing vegetation degradation may surpass the area showing improvement in the future.The study identified that vegetation distribution was influenced by both natural and anthropogenic factors for the whole study area.Precipitation,surface types and land use type were the primary factors with q values above 0.5.During the study period,impacts of GDP,nighttime lights and population density among anthropogenic factors on vegetation distribution increased by 130%,125%and 41%,respectively.Conversely,except for slope and aspect,natural factors'influence on vegetation distribution declined by 5%to 26%.The impact of driving factors on NDVI distribution varied across ecological regions.In Fenwei Basin Agro-Ecoregion(EcoregionⅢ),the influence of anthropogenic factors on vegetation distribution was greater than that in the other three ecoregions.Precipitation primarily affected the vegetation distribution in Loess Plateau Agricultural and Grassland Ecoregion(EcoregionⅡ).Additionally,the combined interactive effects of factors had a stronger influence on NDVI distribution than any single factor.These findings provide valuable insights for local governments in Shaanxi Province to develop targeted ecological restoration and environmental management policies.展开更多
Ternary geopolymers incorporating multiple solid wastes such as steel slag(SS),fly ash(FA),and granulated blast furnace slag(GBFS)are considered environmentally friendly and exhibit enhanced performance.However,the me...Ternary geopolymers incorporating multiple solid wastes such as steel slag(SS),fly ash(FA),and granulated blast furnace slag(GBFS)are considered environmentally friendly and exhibit enhanced performance.However,the mechanisms governing strength development and the design of optimal mixtures are not fully understood due to the complexity of their components.This study presents the development of four machine learning mod-els-Artificial Neural Network(ANN),Support Vector Regression(SVR),Extremely Randomized Tree(ERT),and Gradient Boosting Regression(GBR)-for predicting the unconfined compressive strength(UCS)of ternary geopolymers.The models were trained using a dataset comprising 120 mixtures derived from laboratory tests.Shapley Additive Explanations analysis was employed to interpret the machine learning models and elucidate the influence of different components on the properties of ternary geopolymers.The results indicate that ANN ex-hibits the highest predictive accuracy for UCS(R=0.949).Furthermore,the UCS of ternary geopolymers is most sensitive to the content of GBFS.This study provides valuable insights for optimizing the mix proportions in ternary blended geopolymer mixtures.展开更多
The long transaction latency and low throughput of blockchain are the key challenges affecting the large-scale adoption of blockchain technology. Sharding technology is a primary solution by divides the blockchain net...The long transaction latency and low throughput of blockchain are the key challenges affecting the large-scale adoption of blockchain technology. Sharding technology is a primary solution by divides the blockchain network into multiple independent shards for parallel transaction processing. However, most existing random or modular schemes fail to consider the transactional relationships between accounts, which leads to a high proportion of cross-shard transactions, thereby increasing the communication overhead and transaction confirmation latency between shards. To solve this problem, this paper proposes a blockchain sharding algorithm based on account degree and frequency (DFSA). The algorithm takes into account both account degree and weight relationships between accounts. The blockchain transaction network is modeled as an undirected weighted graph, and community detection algorithms are employed to analyze the correlations between accounts. Strong-correlated accounts are grouped into the same shard, and a multi-shard blockchain network is constructed. Additionally, to further reduce the number of cross-shard transactions, this paper designs a random redundancy strategy based on account correlation, which randomly selects strong-correlated accounts and stores them redundantly in another shard, thus original cross-shard transactions can be verified and confirmed within the same shard. Simulation experiments demonstrate that DFSA outperforms the random sharding algorithm (RSA), modular sharding algorithm (MSA), and label propagation algorithm (LPA) in terms of cross-shard transaction proportion, latency, and throughput. Therefore, DFSA can effectively reduce cross-shard transaction proportion and lower transaction confirmation latency.展开更多
Extracting typical operational scenarios is essential for making flexible decisions in the dispatch of a new power system.A novel deep time series aggregation scheme(DTSAs)is proposed to generate typical operational s...Extracting typical operational scenarios is essential for making flexible decisions in the dispatch of a new power system.A novel deep time series aggregation scheme(DTSAs)is proposed to generate typical operational scenarios,considering the large amount of historical operational snapshot data.Specifically,DTSAs analyse the intrinsic mechanisms of different scheduling operational scenario switching to mathematically represent typical operational scenarios.A Gramian angular summation field-based operational scenario image encoder was designed to convert operational scenario sequences into highdimensional spaces.This enables DTSAs to fully capture the spatiotemporal characteristics of new power systems using deep feature iterative aggregation models.The encoder also facilitates the generation of typical operational scenarios that conform to historical data distributions while ensuring the integrity of grid operational snapshots.Case studies demonstrate that the proposed method extracted new fine-grained power system dispatch schemes and outperformed the latest high-dimensional feature-screening methods.In addition,experiments with different new energy access ratios were conducted to verify the robustness of the proposed method.DTSAs enable dispatchers to master the operation experience of the power system in advance,and actively respond to the dynamic changes of the operation scenarios under the high access rate of new energy.展开更多
汽车悬架控制系统是一个由较多非线性因素共同作用的复杂系统,针对传统PID控制效果不理想的问题,通过数值拟合的方式引入弹簧与阻尼等非线性影响因素,建立1/4汽车悬架非线性动力学模型,借鉴免疫反馈原理,结合积分控制的规律,提出一种模...汽车悬架控制系统是一个由较多非线性因素共同作用的复杂系统,针对传统PID控制效果不理想的问题,通过数值拟合的方式引入弹簧与阻尼等非线性影响因素,建立1/4汽车悬架非线性动力学模型,借鉴免疫反馈原理,结合积分控制的规律,提出一种模糊免疫PID(proportion integral derivative)控制方法,并利用免疫进化算法进行参数优化设计。仿真结果表明,该方法在汽车非线性悬架控制系统中可行且有效,其控制器性能也优于常规的PID控制器,具有更好的响应特性,同时也提高了汽车的操作稳定性和乘坐舒适性。展开更多
[Objective] This study aimed to examine the effect of different proportions of Wolffia on the growth of Procambarus clarkia in 2 kinds of community scales. [Method] Six proportions of baits mixed by watermeal and comm...[Objective] This study aimed to examine the effect of different proportions of Wolffia on the growth of Procambarus clarkia in 2 kinds of community scales. [Method] Six proportions of baits mixed by watermeal and commercial feed (0, 20%, 40%, 60%, 80%, and 100%) were designed to feed the Procambarus clarkia juveniles in 2 community scales to research the growth situation of the crayfish in different mixed baits. The growth differences between the minimal community and the larger community of crayfish in the same proportion of Wolffia were compared. [Result] The growth situations of crayfish in the 2 community scales at different proportions of watermeal were as follows: the body length was the longest in 60% watermeal group, and shortest in the pure watermeal group; the regularity was the best in the 20% watermeal group; no matter the minimal community or the larger community, there was no significant difference in the survival rate between different watermeal proportions. The growth situations of crayfish in the 2 community scales at specific proportion of watermeal were: the average body length of the minimal community was significantly greater than the larger community, and the survival rate also greater than the latter one, but the difference was not significant. [Conclusion] Considering all kinds of index such as growth, survival rate, regularity, the appropriate proportion of the baits mixed by watermeal and commercial feed is 40% to 60%; big community scale has significant inhibition on growth of crayfish, thus, there should be barriers when cultivating Procambarus clarkia juvenile.展开更多
[Objective] The paper was to study the nitrogen application amount and nitrogen application model for high grade hybrid rapeseed （Brassica napus L.） to get high yield. [Method] With ＂Youyan 599＂ and ＂Sanbei 98＂ ...[Objective] The paper was to study the nitrogen application amount and nitrogen application model for high grade hybrid rapeseed （Brassica napus L.） to get high yield. [Method] With ＂Youyan 599＂ and ＂Sanbei 98＂ as materials, using quadratic regression orthogonal gyration combination design, the impact of nitrogen application amount during various periods on rapeseed yield was studied. [Result] The combinations of factors to obtain the highest yield index （2 898.211 kg / hm 2 ） of ＂Youyan 599＂ were as follows： living rape fertilizer 89.27 kg / hm 2 , opening fertilizer 120 kg / hm 2 , 12 th lunar month fertilizer 101.12 kg / hm 2 , total nitrogen application amount 310.39 kg / hm 2 . The proportions of living rape fertilizer, opening fertilizer and 12th lunar month fertilizer were 28.76%, 38.66% and 32.58%, respectively. The combinations of factors to obtain the highest yield index （2 870.14 kg/hm 2 ） of ＂Sanbei 98＂ were as follows： living rape fertilizer 120 kg / hm 2 , opening fertilizer 120 kg / hm 2 , 12 th lunar month fertilizer 37.55kg / hm 2 , total nitrogen application amount 277.55 kg / hm 2 . The proportions of living rape fertilizer, opening fertilizer and 12 th lunar month fertilizer were 43.24%, 43.24% and 13.53%, respectively. The combinations of factors to obtain the highest yield index of two combined varieties （2 813.82 kg/hm 2 ）were as follows： living rape fertilizer 120 kg/hm 2 , opening fertilizer 120 kg/hm 2 , 12 th lunar month fertilizer 76.23 kg/hm 2 , total nitrogen application amount 316.23 kg/hm 2 . The proportions of living rape fertilizer, opening fertilizer and 12 th lunar month fertilizer were 37.95% , 37.95% and 24.11% , respectively. [Conclusion] The paper provided theoretical basis for high yield cultivation of high grade hybridized rapeseed.展开更多
为提升船用汽轮发电机组大幅变工况时的控制精度和鲁棒性,以船用汽轮机调节系统各部件的模块化数学模型为基础,建立汽轮机组数字电液(digital electric hydraulic,DEH)闭环模糊比例、积分、微分(proportion integration derivative,PID...为提升船用汽轮发电机组大幅变工况时的控制精度和鲁棒性,以船用汽轮机调节系统各部件的模块化数学模型为基础,建立汽轮机组数字电液(digital electric hydraulic,DEH)闭环模糊比例、积分、微分(proportion integration derivative,PID)控制模型;融合遗传算法的选择、交叉、变异和自适应递减权重法,提出遗传粒子群智能优化算法,并结合标准测试函数验证提出算法具有较高的收敛速度和精度;基于遗传粒子群智能优化算法建立汽轮机变工况自适应智能模糊PID控制模型,实现模糊PID的量化因子与比例因子最优化设计,进而开展船用汽轮发电机组大幅变工况动态特性及扰动因素影响分析,结果表明本文建立的自适应智能模糊PID控制模型具有更好的控制稳态性能与鲁棒性,为船用汽轮机组大幅度变工况智能控制优化设计提供了有力的技术支撑。展开更多
The purpose of this study is to determine whether advancing age andheart failure are independent predictors of increased mortality afrer acutemyocardial infarction(AMI)We reviewed the clinical data of 1068 in-patients...The purpose of this study is to determine whether advancing age andheart failure are independent predictors of increased mortality afrer acutemyocardial infarction(AMI)We reviewed the clinical data of 1068 in-patients(344 senile/724 nonsenile)with AMI.The results showed atypicalpresentations of infarction-related symptoms in the elderly are common,with consequent delay in the diagnosis and treatment The elderly patientshad a high proportion of systemic hypertension(43.9%),non Q wave AM/(36%)and heart failure(35.5%),On the contrast,the proportion of that innonsenile patients were 33%,8Vo and 16.4% respectively.In elderlypatients,several complications:of AMI are more common,asinterventricular septum perforation(2%),cardiogenic shock(19.8%),arthythmia(61.9%).Heart failure was more frequent in patients with leftventricular ejection fraction(LVEF)≤35%,previous heart failure ormyocardial infarction,and anterior location infarction.Those with severecongestive heart failure had a mortality of 33.2% compared with 24.5% forthose with moderate heart failure and 13.51% for those with no heart failurein the first eight weeks.The following factors were associated with anincreased risk of death:older age,longer delay before admission to hospital,no prescription of beta-blaekers and a previous history of infarctionOur data suggested that the prognosis after AMI was directly related toadvaneeing age and the severity of congestive heart failure.Thedevelopment of congestive heart failure was an independent predictor ofdeath.The increasing incidence and mortality were closely related toimpaired myocardial reserve.The present benefits,as pointed out by therecent progress in AMI therapy,must be employed in the treatment of olderinfarcted patients More aggressive management in elderly patients shouldoe evaluated for its potential to reduce mortality.展开更多
rate,ratio,proportion三词都可以表示“比例”。表此义时,其差别甚是微妙,值得注意。现作如下辨析: rate指“比、比率、比例”,如:mortality rate死亡率,tax rate税率,rate of rejects废品率,rate of attendance出勤率,crime rate犯罪...rate,ratio,proportion三词都可以表示“比例”。表此义时,其差别甚是微妙,值得注意。现作如下辨析: rate指“比、比率、比例”,如:mortality rate死亡率,tax rate税率,rate of rejects废品率,rate of attendance出勤率,crime rate犯罪率,divorce rate离婚率,accident rate事故发生率。从以上例证不难看出,这里所谓的“比、比率”是指部分相对整体形成的比率,即a mea-sure of a part with respect to the whole。如“废品率”是产品“总量”减去“正品量”然后除以总量而得来的。展开更多
Objective: Precise prevention is more desired for cervical cancer due to the huge population, high prevalence of human papillomavirus(HPV) infection in China and the vision of screen-and-treat strategies in low-and mi...Objective: Precise prevention is more desired for cervical cancer due to the huge population, high prevalence of human papillomavirus(HPV) infection in China and the vision of screen-and-treat strategies in low-and middleincome countries(LMICs). Considerations of combining type-specific prevalence and attribution proportion to high-grade cervical intraepithelial neoplasia are informative to more precise and effective region-specific cervical cancer prevention and control programs. The aim of the current study was to determine the genotype distribution of HPV and attribution to cervical precancerous lesions among women from rural areas in North China.Methods: A total of 9,526 women participated in the cervical cancer screening project in rural China. The samples of women who tested positive for HPV were retested with a polymerase chain reaction(PCR)-based HPV genotyping test. The attribution proportion of specific high-risk human papillomavirus(HR-HPV) types for different grades of cervical lesions was calculated by using the type contribution weighting method.Results: A total of 22.2%(2,112/9,526) of women were HR-HPV positive and HPV52(21.7%) was the most common HR-HPV genotype, followed by HPV58(18.2%), HPV53(18.2%) and HPV16(16.2%). The top three genotypes detected in HR-HPV-positive cervical intraepithelial neoplasia(CIN)1 were HPV16(36.7%), HPV58(20.4%), HPV56(15.3%). Among CIN2+, the most frequent genotypes were HPV16(75.6%), HPV52(17.8%),HPV58(16.7%). HPV16, 56, 58, 53, 52, 59, 68, and 18 combined were attributed to 84.17% of all CIN1 lesions,and HPV16, 58, and 52 combined were attributed to 86.98% of all CIN2+ lesions.Conclusions: The prevalence of HR-HPV infection among women from rural areas in North China was high and HPV16, HPV58, HPV52 had paramount attributable fraction in CIN2+. Type-specific HPV prevalence and attribution proportion to cervical precancerous lesions should be taken into consideration in the development of vaccines and strategy for screening in this population.展开更多
Understanding the spatial and temporal variations of cropping systems is very important for agricultural policymaking and food security assessment, and can provide a basis for national policies regarding cropping syst...Understanding the spatial and temporal variations of cropping systems is very important for agricultural policymaking and food security assessment, and can provide a basis for national policies regarding cropping systems adjustment and agricultural adaptation to climate change. With rapid development of society and the economy, China＇s cropping structure has profoundly changed since the reform and opening up in 1978, but there has been no systematic investigation of the pattern, process and characteristics of these changes. In view of this, a crop area database for China was acquired and compiled at the county level for the period 1980-2011, and linear regression and spatial analysis were employed to investigate the cropping structure type and cropping proportion changes at the national level. This research had three main findings： （1） China＇s cropping structure has undergone significant changes since 2002; the richness of cropping structure types has increased significantly and a diversified-type structure has gradually replaced the single types. The single-crop types--dominated by rice, wheat or maize--declined, affected by the combination of these three major food crops in mixed plantings and conversion of some of their planting area to other crops. （2） In the top 10 types, 82.7% of the county-level cropping structure was rice, wheat, maize and their combinations in 1980; however, this proportion decreased to 50.7% in 2011, indicating an adjustment period of China＇s cropping structure. Spatial analysis showed that 63.8% of China＇s counties adjusted their cropping structure, with the general change toward reducing the main food types and increasing fruits and vegetables during 1980-2011. （3） At the national level, the grain-planting pattern dominated by rice shifted to coexistence of rice, wheat and maize during this period. There were significant decreasing trends for 47% of rice, 61% of wheat and 29.6% of maize cropping counties. The pattern of maize cropping had the most significant change, with the maize proportion decreasing in the zone from north- eastern to southwestern China during this period. Cities and their surroundings were hotspots for cropping structural adjustment. Urbanization has significantly changed cropping structure, with most of these regions showing rapid increases in the proportion of fruit and vegetables.Our research suggests that the policy of cropping structural adjustment needs to consider geographical characteristics and spatial planning of cropping systems. In this way, the future direction of cropping structural adjustment wilt be appropriate and scientifically based, such as where there is a need to maintain or increase rice and wheat cropping, increase soybean and decrease maize, and increase the supply of fruit and vegetables.展开更多
The reasonable design of the composition of the composite materials is of great significance to optimized the electromagnetic(EM)wave absorption performance.Herein,the Ni/NiO@C hybrid composites with tunable Ni propor...The reasonable design of the composition of the composite materials is of great significance to optimized the electromagnetic(EM)wave absorption performance.Herein,the Ni/NiO@C hybrid composites with tunable Ni proportion were successfully synthesized through a two-step process.With the assistance of X-ray diffraction with refinement treatment,the specific proportion of Ni of as-obtained hybrid composites could be obtained.Employing controlling calcination time to adjust the Ni content of Ni/NiO@C hybrid composites,it has been found that the composite carbonized at 500℃exhibited remarkable EM wave absorption with the minimum reflection loss(RLmin)of-49.1 dB at 4.9 mm and the widest effective absorption bandwidth(EABmax)of 4.56 GHz at 2.1 mm.Moreover,by adjusting the Ni source,the optimal EM wave absorption performance could be achieved.Results illustrated that the N3PC with the Ni proportion of 13.17%showed the RLm inas low as-51.1 dB at 2.4 mm and the EABmax was 5.12 GHz at 2.7 mm.It is worth noting that this work demonstrates the relevance of the composition and EM wave absorption performance of hybrid composites,which offers a feasible reference for the absorption mechanism of absorber.展开更多
文摘Background: Maternal mortality remains a major public health problem worldwide. Objectives: Our study aims to present the results of an analysis of reviews of maternal deaths at HGOPY. Methodology: This was a descriptive cross-sectional study with retrospective data collection from archived records and reviewed maternal death reports. Our study lasted 8 months, from October 1, 2023 to May 31, 2024. The study covered maternal death files at the HGOPY over an 8-year period, from 1st of January 2016 to the 31st of December 2023. Data were processed and analyzed using Statitical Paquage for Social Science (SPSS) version 26.0. Results: We counted a total of 160 maternal deaths, of which 97 had been reviewed. We excluded 61 deceased women reviewed and retained 33. We recorded a cumulative total of 160 maternal deaths and 19,651 live births. The peak in the proportion of maternal deaths at the Yaoundé Gynaeco-Obstetric and Paediatric Hospital was in 2021, with a proportion of 0.013. No maternal deaths had been reviewed between 2016 to 2017. Most deaths (64%) occurred between 37 and 40 weeks. The majority (30.5%) were aged between 30 and 35. The data show that 80.6% of maternal deaths were due to direct obstetric causes, while 19.4% were due to indirect causes. Most deaths (69.4%) were preventable. Only 8.3% were not preventable. Conclusion: Concerted efforts must be made to adapt maternal death prevention and management strategies to local contexts in order to significantly reduce these alarming figures.
基金Supported by the Shandong Provincial Natural Science Foundation(No.ZR2020QC043)。
文摘The abundance of live and dead Oithona similis in Jiaozhou Bay,Shandong,China,was investigated monthly from December 2008 to November 2009 via the neutral red staining method.The annual variation in total abundance was similar for females,males,and copepodites,with a main numerical peak from February to July and a minor peak in November,but the variations in carcass abundance and death proportion were different.The monthly average abundance of male and copepodite carcasses significantly increased with their total abundance(P<0.001),whereas no such correlation was observed for females.The abundance of female carcasses peaked at 12.4 inds./m^(3) in November but remained below 3.0 inds./m^(3) in all other months.The monthly average death proportion ranged 0.3%-4.9% for females,3.6%-25.7% for males,and 2.6%-8.4% for copepodites.On average,the death proportion of males was 9.2 times greater than that of females and 3.5 times greater than that of copepodites.Therefore,significant sexual difference exists in the non-predatory mortality of O.similis and this difference is an important cause of the female-skewed sex ratios observed in the field.
基金supported by the National Key Research and Development Program of China(Grant No.2022YFF0801304)Philosophy and Social Science Foundation of China(Grant No.23BRK011,24CTJ021)+3 种基金the Humanities and Social Sciences Research Planning Fund of the Ministry of Education,China(Grant No.22YJAZH020)Shaanxi Provincial Social Science Foundation(Grant No.2024D041)Graduate Innovation Funds of Xi’an University of Finance and Economics(Grant No.23YC011)the Youth Innovation Team of Shaanxi Universities,China。
文摘The Loess Plateau region in China is characterized by a fragile environment,where vegetation is susceptible to both natural variations and anthropogenic influences.Previous research has indicated a greening trend in vegetation across the Loess Plateau over the past two decades.However,the specific contributions of natural and anthropogenic drivers,both individually and interactively,to vegetation distribution remain unclear.To address this gap,we conducted a study using Shaanxi Province as a case area.Utilizing multisource data,we employed the Geographical Detector Model(GDM)to analyze the impacts of natural and human related factors on vegetation distribution.Our analysis revealed that the average NDVI(Normalized Difference Vegetation Index)increased at a rate of 0.006 per year from 2000 to 2021.Notably,88.8%of the region experienced vegetation greening,while 4.5%showed significant declines in NDVI,particularly in areas,such as Xi'an,Weinan,Baoji,Hanzhong,and Ankang.Furthermore,NDVI trend projections suggest that the area undergoing vegetation degradation may surpass the area showing improvement in the future.The study identified that vegetation distribution was influenced by both natural and anthropogenic factors for the whole study area.Precipitation,surface types and land use type were the primary factors with q values above 0.5.During the study period,impacts of GDP,nighttime lights and population density among anthropogenic factors on vegetation distribution increased by 130%,125%and 41%,respectively.Conversely,except for slope and aspect,natural factors'influence on vegetation distribution declined by 5%to 26%.The impact of driving factors on NDVI distribution varied across ecological regions.In Fenwei Basin Agro-Ecoregion(EcoregionⅢ),the influence of anthropogenic factors on vegetation distribution was greater than that in the other three ecoregions.Precipitation primarily affected the vegetation distribution in Loess Plateau Agricultural and Grassland Ecoregion(EcoregionⅡ).Additionally,the combined interactive effects of factors had a stronger influence on NDVI distribution than any single factor.These findings provide valuable insights for local governments in Shaanxi Province to develop targeted ecological restoration and environmental management policies.
基金support provided by the Natural Science Foundation of China(Grant No.52208240)S&T Program of Hebei(Grant No.E2022202051,236Z3809G)+1 种基金Education Department of Hebei Province(Grant No.:C20220311)Hebei University of Technology(Grant No.:24/424132021).
文摘Ternary geopolymers incorporating multiple solid wastes such as steel slag(SS),fly ash(FA),and granulated blast furnace slag(GBFS)are considered environmentally friendly and exhibit enhanced performance.However,the mechanisms governing strength development and the design of optimal mixtures are not fully understood due to the complexity of their components.This study presents the development of four machine learning mod-els-Artificial Neural Network(ANN),Support Vector Regression(SVR),Extremely Randomized Tree(ERT),and Gradient Boosting Regression(GBR)-for predicting the unconfined compressive strength(UCS)of ternary geopolymers.The models were trained using a dataset comprising 120 mixtures derived from laboratory tests.Shapley Additive Explanations analysis was employed to interpret the machine learning models and elucidate the influence of different components on the properties of ternary geopolymers.The results indicate that ANN ex-hibits the highest predictive accuracy for UCS(R=0.949).Furthermore,the UCS of ternary geopolymers is most sensitive to the content of GBFS.This study provides valuable insights for optimizing the mix proportions in ternary blended geopolymer mixtures.
基金supported by the National Natural Science Foundation of China(Grant No.61802301)awarded to J.Lithe Postgraduate Innovation Fund Project of Xi’an Shiyou University(Grant No.YCX2513159).
文摘The long transaction latency and low throughput of blockchain are the key challenges affecting the large-scale adoption of blockchain technology. Sharding technology is a primary solution by divides the blockchain network into multiple independent shards for parallel transaction processing. However, most existing random or modular schemes fail to consider the transactional relationships between accounts, which leads to a high proportion of cross-shard transactions, thereby increasing the communication overhead and transaction confirmation latency between shards. To solve this problem, this paper proposes a blockchain sharding algorithm based on account degree and frequency (DFSA). The algorithm takes into account both account degree and weight relationships between accounts. The blockchain transaction network is modeled as an undirected weighted graph, and community detection algorithms are employed to analyze the correlations between accounts. Strong-correlated accounts are grouped into the same shard, and a multi-shard blockchain network is constructed. Additionally, to further reduce the number of cross-shard transactions, this paper designs a random redundancy strategy based on account correlation, which randomly selects strong-correlated accounts and stores them redundantly in another shard, thus original cross-shard transactions can be verified and confirmed within the same shard. Simulation experiments demonstrate that DFSA outperforms the random sharding algorithm (RSA), modular sharding algorithm (MSA), and label propagation algorithm (LPA) in terms of cross-shard transaction proportion, latency, and throughput. Therefore, DFSA can effectively reduce cross-shard transaction proportion and lower transaction confirmation latency.
基金The Key R&D Project of Jilin Province,Grant/Award Number:20230201067GX。
文摘Extracting typical operational scenarios is essential for making flexible decisions in the dispatch of a new power system.A novel deep time series aggregation scheme(DTSAs)is proposed to generate typical operational scenarios,considering the large amount of historical operational snapshot data.Specifically,DTSAs analyse the intrinsic mechanisms of different scheduling operational scenario switching to mathematically represent typical operational scenarios.A Gramian angular summation field-based operational scenario image encoder was designed to convert operational scenario sequences into highdimensional spaces.This enables DTSAs to fully capture the spatiotemporal characteristics of new power systems using deep feature iterative aggregation models.The encoder also facilitates the generation of typical operational scenarios that conform to historical data distributions while ensuring the integrity of grid operational snapshots.Case studies demonstrate that the proposed method extracted new fine-grained power system dispatch schemes and outperformed the latest high-dimensional feature-screening methods.In addition,experiments with different new energy access ratios were conducted to verify the robustness of the proposed method.DTSAs enable dispatchers to master the operation experience of the power system in advance,and actively respond to the dynamic changes of the operation scenarios under the high access rate of new energy.
文摘汽车悬架控制系统是一个由较多非线性因素共同作用的复杂系统,针对传统PID控制效果不理想的问题,通过数值拟合的方式引入弹簧与阻尼等非线性影响因素,建立1/4汽车悬架非线性动力学模型,借鉴免疫反馈原理,结合积分控制的规律,提出一种模糊免疫PID(proportion integral derivative)控制方法,并利用免疫进化算法进行参数优化设计。仿真结果表明,该方法在汽车非线性悬架控制系统中可行且有效,其控制器性能也优于常规的PID控制器,具有更好的响应特性,同时也提高了汽车的操作稳定性和乘坐舒适性。
文摘[Objective] This study aimed to examine the effect of different proportions of Wolffia on the growth of Procambarus clarkia in 2 kinds of community scales. [Method] Six proportions of baits mixed by watermeal and commercial feed (0, 20%, 40%, 60%, 80%, and 100%) were designed to feed the Procambarus clarkia juveniles in 2 community scales to research the growth situation of the crayfish in different mixed baits. The growth differences between the minimal community and the larger community of crayfish in the same proportion of Wolffia were compared. [Result] The growth situations of crayfish in the 2 community scales at different proportions of watermeal were as follows: the body length was the longest in 60% watermeal group, and shortest in the pure watermeal group; the regularity was the best in the 20% watermeal group; no matter the minimal community or the larger community, there was no significant difference in the survival rate between different watermeal proportions. The growth situations of crayfish in the 2 community scales at specific proportion of watermeal were: the average body length of the minimal community was significantly greater than the larger community, and the survival rate also greater than the latter one, but the difference was not significant. [Conclusion] Considering all kinds of index such as growth, survival rate, regularity, the appropriate proportion of the baits mixed by watermeal and commercial feed is 40% to 60%; big community scale has significant inhibition on growth of crayfish, thus, there should be barriers when cultivating Procambarus clarkia juvenile.
基金Supported by Construction Project of National Rapeseed Modern Industrial Technology System (nycytx-00563)Guizhou Academy of Agricultural Sciences "Research of High Yield and High Quality Cultivation Technology for High Grade Hybrid Rapeseed with High Oil" [C ZX(2007)015]+2 种基金Department of Agriculture of Guizhou Province "Research, Promotion and Application of High Yield Cultivation Technology for Hybridized Rapeseed of New Variety Youyan 599" [QNYZZ (2009) 007]Guizhou Academy of Agricultural Sciences "Large Area Intermediate Experiment, Promotion and Application of Hybridized Rapeseed Youyan 599" [QNKZX (2009) 030]Department of Agriculture of Guizhou Province "Integrated Innovation of Seed Production Techniques and Large Area Demonstration for New High Oil Rapeseed Hybrid Variety Sanbei 98 [QKH NY (2010) 3087]~~
文摘[Objective] The paper was to study the nitrogen application amount and nitrogen application model for high grade hybrid rapeseed （Brassica napus L.） to get high yield. [Method] With ＂Youyan 599＂ and ＂Sanbei 98＂ as materials, using quadratic regression orthogonal gyration combination design, the impact of nitrogen application amount during various periods on rapeseed yield was studied. [Result] The combinations of factors to obtain the highest yield index （2 898.211 kg / hm 2 ） of ＂Youyan 599＂ were as follows： living rape fertilizer 89.27 kg / hm 2 , opening fertilizer 120 kg / hm 2 , 12 th lunar month fertilizer 101.12 kg / hm 2 , total nitrogen application amount 310.39 kg / hm 2 . The proportions of living rape fertilizer, opening fertilizer and 12th lunar month fertilizer were 28.76%, 38.66% and 32.58%, respectively. The combinations of factors to obtain the highest yield index （2 870.14 kg/hm 2 ） of ＂Sanbei 98＂ were as follows： living rape fertilizer 120 kg / hm 2 , opening fertilizer 120 kg / hm 2 , 12 th lunar month fertilizer 37.55kg / hm 2 , total nitrogen application amount 277.55 kg / hm 2 . The proportions of living rape fertilizer, opening fertilizer and 12 th lunar month fertilizer were 43.24%, 43.24% and 13.53%, respectively. The combinations of factors to obtain the highest yield index of two combined varieties （2 813.82 kg/hm 2 ）were as follows： living rape fertilizer 120 kg/hm 2 , opening fertilizer 120 kg/hm 2 , 12 th lunar month fertilizer 76.23 kg/hm 2 , total nitrogen application amount 316.23 kg/hm 2 . The proportions of living rape fertilizer, opening fertilizer and 12 th lunar month fertilizer were 37.95% , 37.95% and 24.11% , respectively. [Conclusion] The paper provided theoretical basis for high yield cultivation of high grade hybridized rapeseed.
文摘为提升船用汽轮发电机组大幅变工况时的控制精度和鲁棒性,以船用汽轮机调节系统各部件的模块化数学模型为基础,建立汽轮机组数字电液(digital electric hydraulic,DEH)闭环模糊比例、积分、微分(proportion integration derivative,PID)控制模型;融合遗传算法的选择、交叉、变异和自适应递减权重法,提出遗传粒子群智能优化算法,并结合标准测试函数验证提出算法具有较高的收敛速度和精度;基于遗传粒子群智能优化算法建立汽轮机变工况自适应智能模糊PID控制模型,实现模糊PID的量化因子与比例因子最优化设计,进而开展船用汽轮发电机组大幅变工况动态特性及扰动因素影响分析,结果表明本文建立的自适应智能模糊PID控制模型具有更好的控制稳态性能与鲁棒性,为船用汽轮机组大幅度变工况智能控制优化设计提供了有力的技术支撑。
文摘The purpose of this study is to determine whether advancing age andheart failure are independent predictors of increased mortality afrer acutemyocardial infarction(AMI)We reviewed the clinical data of 1068 in-patients(344 senile/724 nonsenile)with AMI.The results showed atypicalpresentations of infarction-related symptoms in the elderly are common,with consequent delay in the diagnosis and treatment The elderly patientshad a high proportion of systemic hypertension(43.9%),non Q wave AM/(36%)and heart failure(35.5%),On the contrast,the proportion of that innonsenile patients were 33%,8Vo and 16.4% respectively.In elderlypatients,several complications:of AMI are more common,asinterventricular septum perforation(2%),cardiogenic shock(19.8%),arthythmia(61.9%).Heart failure was more frequent in patients with leftventricular ejection fraction(LVEF)≤35%,previous heart failure ormyocardial infarction,and anterior location infarction.Those with severecongestive heart failure had a mortality of 33.2% compared with 24.5% forthose with moderate heart failure and 13.51% for those with no heart failurein the first eight weeks.The following factors were associated with anincreased risk of death:older age,longer delay before admission to hospital,no prescription of beta-blaekers and a previous history of infarctionOur data suggested that the prognosis after AMI was directly related toadvaneeing age and the severity of congestive heart failure.Thedevelopment of congestive heart failure was an independent predictor ofdeath.The increasing incidence and mortality were closely related toimpaired myocardial reserve.The present benefits,as pointed out by therecent progress in AMI therapy,must be employed in the treatment of olderinfarcted patients More aggressive management in elderly patients shouldoe evaluated for its potential to reduce mortality.
文摘rate,ratio,proportion三词都可以表示“比例”。表此义时,其差别甚是微妙,值得注意。现作如下辨析: rate指“比、比率、比例”,如:mortality rate死亡率,tax rate税率,rate of rejects废品率,rate of attendance出勤率,crime rate犯罪率,divorce rate离婚率,accident rate事故发生率。从以上例证不难看出,这里所谓的“比、比率”是指部分相对整体形成的比率,即a mea-sure of a part with respect to the whole。如“废品率”是产品“总量”减去“正品量”然后除以总量而得来的。
基金supported by the China Medical Board (CMB) (No: 16-255)Chinese Academy of Medical Science Initiative for Innovative Medicine (No: 2017-I2M1-002)
文摘Objective: Precise prevention is more desired for cervical cancer due to the huge population, high prevalence of human papillomavirus(HPV) infection in China and the vision of screen-and-treat strategies in low-and middleincome countries(LMICs). Considerations of combining type-specific prevalence and attribution proportion to high-grade cervical intraepithelial neoplasia are informative to more precise and effective region-specific cervical cancer prevention and control programs. The aim of the current study was to determine the genotype distribution of HPV and attribution to cervical precancerous lesions among women from rural areas in North China.Methods: A total of 9,526 women participated in the cervical cancer screening project in rural China. The samples of women who tested positive for HPV were retested with a polymerase chain reaction(PCR)-based HPV genotyping test. The attribution proportion of specific high-risk human papillomavirus(HR-HPV) types for different grades of cervical lesions was calculated by using the type contribution weighting method.Results: A total of 22.2%(2,112/9,526) of women were HR-HPV positive and HPV52(21.7%) was the most common HR-HPV genotype, followed by HPV58(18.2%), HPV53(18.2%) and HPV16(16.2%). The top three genotypes detected in HR-HPV-positive cervical intraepithelial neoplasia(CIN)1 were HPV16(36.7%), HPV58(20.4%), HPV56(15.3%). Among CIN2+, the most frequent genotypes were HPV16(75.6%), HPV52(17.8%),HPV58(16.7%). HPV16, 56, 58, 53, 52, 59, 68, and 18 combined were attributed to 84.17% of all CIN1 lesions,and HPV16, 58, and 52 combined were attributed to 86.98% of all CIN2+ lesions.Conclusions: The prevalence of HR-HPV infection among women from rural areas in North China was high and HPV16, HPV58, HPV52 had paramount attributable fraction in CIN2+. Type-specific HPV prevalence and attribution proportion to cervical precancerous lesions should be taken into consideration in the development of vaccines and strategy for screening in this population.
基金National Natural Science Foundation of China,No.41571172Ministry of Finance of China through the Non-Profit National Research Institute,No.2017-CAAS-30
文摘Understanding the spatial and temporal variations of cropping systems is very important for agricultural policymaking and food security assessment, and can provide a basis for national policies regarding cropping systems adjustment and agricultural adaptation to climate change. With rapid development of society and the economy, China＇s cropping structure has profoundly changed since the reform and opening up in 1978, but there has been no systematic investigation of the pattern, process and characteristics of these changes. In view of this, a crop area database for China was acquired and compiled at the county level for the period 1980-2011, and linear regression and spatial analysis were employed to investigate the cropping structure type and cropping proportion changes at the national level. This research had three main findings： （1） China＇s cropping structure has undergone significant changes since 2002; the richness of cropping structure types has increased significantly and a diversified-type structure has gradually replaced the single types. The single-crop types--dominated by rice, wheat or maize--declined, affected by the combination of these three major food crops in mixed plantings and conversion of some of their planting area to other crops. （2） In the top 10 types, 82.7% of the county-level cropping structure was rice, wheat, maize and their combinations in 1980; however, this proportion decreased to 50.7% in 2011, indicating an adjustment period of China＇s cropping structure. Spatial analysis showed that 63.8% of China＇s counties adjusted their cropping structure, with the general change toward reducing the main food types and increasing fruits and vegetables during 1980-2011. （3） At the national level, the grain-planting pattern dominated by rice shifted to coexistence of rice, wheat and maize during this period. There were significant decreasing trends for 47% of rice, 61% of wheat and 29.6% of maize cropping counties. The pattern of maize cropping had the most significant change, with the maize proportion decreasing in the zone from north- eastern to southwestern China during this period. Cities and their surroundings were hotspots for cropping structural adjustment. Urbanization has significantly changed cropping structure, with most of these regions showing rapid increases in the proportion of fruit and vegetables.Our research suggests that the policy of cropping structural adjustment needs to consider geographical characteristics and spatial planning of cropping systems. In this way, the future direction of cropping structural adjustment wilt be appropriate and scientifically based, such as where there is a need to maintain or increase rice and wheat cropping, increase soybean and decrease maize, and increase the supply of fruit and vegetables.
基金financially supported by the National Natural Science Foundation of China(Nos.51407134,51801001 and 51801108)Natural Science Foundation of Shandong Province(No.ZR2019YQ24)+5 种基金China Postdoctoral Science Foundation(No.2016M590619,No.2016M601878)Provincial Key Research and Development Program of Shaanxi(No.2019GY-197)the Qingchuang Talents Induction Program of Shandong Higher Education Institution(Research and Innovation Team of Structural-Functional Polymer Composites)the support from The Thousand Talents PlanThe World-Class University and DisciplineThe Taishan Scholar’s Advantageous and Distinctive Discipline Program of Shandong ProvinceThe World-Class Discipline Program of Shandong Province。
文摘The reasonable design of the composition of the composite materials is of great significance to optimized the electromagnetic(EM)wave absorption performance.Herein,the Ni/NiO@C hybrid composites with tunable Ni proportion were successfully synthesized through a two-step process.With the assistance of X-ray diffraction with refinement treatment,the specific proportion of Ni of as-obtained hybrid composites could be obtained.Employing controlling calcination time to adjust the Ni content of Ni/NiO@C hybrid composites,it has been found that the composite carbonized at 500℃exhibited remarkable EM wave absorption with the minimum reflection loss(RLmin)of-49.1 dB at 4.9 mm and the widest effective absorption bandwidth(EABmax)of 4.56 GHz at 2.1 mm.Moreover,by adjusting the Ni source,the optimal EM wave absorption performance could be achieved.Results illustrated that the N3PC with the Ni proportion of 13.17%showed the RLm inas low as-51.1 dB at 2.4 mm and the EABmax was 5.12 GHz at 2.7 mm.It is worth noting that this work demonstrates the relevance of the composition and EM wave absorption performance of hybrid composites,which offers a feasible reference for the absorption mechanism of absorber.
