期刊文献+
共找到2,006篇文章
< 1 2 101 >
每页显示 20 50 100
基于相场模型的三相Rayleigh-Taylor不稳定性的格子Boltzmann方法模拟
1
作者 杨旭光 王欣 袁晓垒 《物理学报》 北大核心 2026年第1期443-458,共16页
基于具有守恒性与相容性的N相相场模型,发展了一种用于高效模拟N相非混溶不可压流体流动的正则化格子Boltzmann方法.通过设计辅助矩,该方法能够精确恢复二阶Allen-Cahn方程与修正的动量方程.通过数值模拟三相液滴透镜铺展与三相Kelvin-H... 基于具有守恒性与相容性的N相相场模型,发展了一种用于高效模拟N相非混溶不可压流体流动的正则化格子Boltzmann方法.通过设计辅助矩,该方法能够精确恢复二阶Allen-Cahn方程与修正的动量方程.通过数值模拟三相液滴透镜铺展与三相Kelvin-Helmholtz不稳定性现象,验证了所发展的N相正则化格子Boltzmann方法的正确性与有效性.最后,对三相Rayleigh-Taylor不稳定性进行了数值模拟与分析,重点探究了雷诺数在500≤Re≤20000范围内(特别是高雷诺数Re=20000工况下)相界面的演化过程,定量分析了两个界面处气泡与尖钉的振幅以及无量纲化速度的变化规律. 展开更多
关键词 相场模型 n相不可压流体 格子BOLTZMAnn方法 RAYLEIGH-TAYLOR不稳定性
在线阅读 下载PDF
Practice and Exploration of Target Management Model for Clinical Pharmacists in Primary Hospitals
2
作者 Xia Zhan Ting Zhou Hongrong Bao 《Journal of Clinical and Nursing Research》 2025年第9期32-41,共10页
Objective:To explore the target management model for clinical pharmacists in primary hospitals facing current shortages of clinical pharmacists,in order to improve the work efficiency and service quality of clinical p... Objective:To explore the target management model for clinical pharmacists in primary hospitals facing current shortages of clinical pharmacists,in order to improve the work efficiency and service quality of clinical pharmacy,and promote the high-quality development of clinical pharmacy in primary hospitals.Methods:Developing a target management model,adopting a wide coverage work model of“1+1+N”(that is,1 clinical pharmacist,1 resident clinical department,and N contracted clinical departments).According to the SMART principle,various work assessment indicators were quantified.This involved setting clear work goals,diversifying work methods,personalizing work methods,standardizing workflows,and using numerical assessment indicators.Regular supervision,inspection,feedback,and improvement mechanisms were implemented.Results:The implementation of the target management model has made the work effectiveness of clinical pharmacists visualized.There were more than 200 annual consultations and multidisciplinary team(MDT)cases,with an opinion adoption rate of 90.2%and a patient improvement rate of 80.6%.More than 1500 rational drug use interventions were conducted,with a suggestion adoption rate of 83.5%.In terms of pharmaceutical indicators control.The intensity of antibacterial drug use in 2024(without CMI adjustment)was 30.07 DDDs,significantly lower than the 2023 value of 33.54 DDDs,and also significantly lower than the provincial average(32.87 DDDs)and the average for hospitals of the same level(32.49 DDDs).The daily usage of intravenous infusion per bed for hospitalized patients was 2.09,a decrease from 2.15 in 2023,significantly lower than the provincial average of 2.71 and the average of 2.56 in hospitals of the same level.The amount of the second batch of national key monitoring drugs accounts for the value was 6.48%,significantly lower than the provincial average of 8.27%and the same level hospital average of 8.82%.In terms of chronic disease pharmaceutical management,taking the pharmaceutical management of patients with chronic heart failure as an example,the usage rates of renin-aldosterone-angiotensin-system inhibitors(RAAS inhibitors)and beta-blockers for heart failure in the management group were 87.88%and 80.81%,respectively,significantly higher-1 than those in the control group(62.22%and 65.56%).Heart rate in the management group(69.54±10.68 times·min-1)was significantly lower than in the control group(80.04±17.68 times·min)(P<0.001).The low-density lipoprotein cholesterol(1.69±0.57 mmol·L-1)was significantly lower than the control group(1.95±0.77 mmol·L-1)(P<0.001),and the 1-year readmission rate was 47.47%,significantly lower than the control group 56.67%.The Minnesota Living with Heart Failure Questionnaire(MLHFQ)Score was(44.20±10.78),significantly lower than the control group(55.89±11.48)(P<0.001),indicating a significant improvement in the patient’s quality of life.Conclusions:The targeted management model for clinical pharmacists can effectively enhance communication and collaboration between clinical pharmacists and clinicians,improve the work efficiency and service quality of clinical pharmacists in primary hospitals,promote the work of clinical pharmacy towards standardization and scientificization,boost the high-quality development of pharmacy in primary hospitals,and also provide new ideas and methods for the management of clinical pharmacists in other primary hospitals. 展开更多
关键词 Clinical pharmacist Target management “1+1+n”Management model Primary hospital Pharmaceutical services
暂未订购
Ultrasound imaging-guided protocol for monitoring tumor growth in orthotopic rat model of hepatocellular carcinoma
3
作者 Aswathy R Devan Sithara Manakkaparambil Sasidharan +5 位作者 Kannoth Panicker Sreekumar Ayalur Kodakara Kochugovindan Unni Sabitha Mangalathillam Abna Ansar Ashok R Unni Lekshmi R Nath 《World Journal of Hepatology》 2025年第10期260-274,共15页
BACKGROUND Syngeneic orthotopic tumor models offer an optimal functional tumor–immune interface for hepatocellular carcinoma research.Yet,unpredictable growth kinetics and spontaneous regression pose major obstacles.... BACKGROUND Syngeneic orthotopic tumor models offer an optimal functional tumor–immune interface for hepatocellular carcinoma research.Yet,unpredictable growth kinetics and spontaneous regression pose major obstacles.Efficient induction protocols and continuous monitoring are therefore essential.Routine exploratory surgeries are ethically untenable,making non-invasive imaging modalities attractive alternatives.High-resolution magnetic resonance imaging and microcomputed tomography deliver detailed insights but incur substantial equipment costs,radiation risks,time demands,and require specialized expertise—challenges that limit their routine use.In contrast,ultrasound(US)imaging emerges as a cost-effective,radiation-free,and rapid approach,facilitating practical and ethical longitudinal assessment of tumor progression in preclinical studies.AIM To optimize the orthotopic hepatocellular carcinoma model and evaluate the potential of US imaging for accurate and cost-effective tumor monitoring.METHODS Hepatocellular carcinoma was induced in 28 Sprague Dawley rats by implanting 5×10^(6) N1S1 cells into the left lateral hepatic lobe.Tumor progression was monitored weekly via US.Upon reaching 100-150 mm^(3),an experimental group(n=14)received Sorafenib(40 mg/kg)orally on alternate days for 28 days;efficacy was compared to untreated controls.US accuracy was validated against micro-computed tomography,gross caliper measurements and histopathological analysis.Reliability and operator proficiency in US assessment were also evaluated.RESULTS US images procured 7-day post-surgery revealed a well-defined hypoechoic nodule at the left liver lobe tip,confirming successful tumor induction(mean volume 130±39 mm^(3)).Only three animals exhibited spontaneous regression by week 2,underscoring the model’s stability.Sorafenib treatment elicited a marked tumor reduction(678±103 mm^(3))vs untreated control(6005±1760 mm^(3)).US assessment demonstrated robust intra and interobserver reproducibility with high sensitivity and specificity for tumor detection.Moreover,US derived volumes correlated strongly with gross caliper measurements,histopathological analysis,and microcomputed tomography imaging,validating its reliability as a non-invasive monitoring tool in preclinical hepatocellular carcinoma studies.CONCLUSION The results demonstrate that US imaging is a reliable,cost-effective,and animal sparing approach with an easy tomaster protocol,enabling monitoring of tumor progression and therapeutic response in orthotopic liver tumor models. 展开更多
关键词 Hepatocellular carcinoma Syngeneic n1S1 orthotopic model Ultrasound imaging Tumor growth monitoring Therapeutic response Cost-effective imaging tool Inter-observer reproducibility Receiver operating characteristics analysis
暂未订购
改进N-K模型在装配式建筑施工安全风险耦合分析中的应用 被引量:4
4
作者 杨文安 徐碧琴 言雨欣 《安全与环境学报》 北大核心 2025年第6期2092-2103,共12页
为了识别装配式建筑施工的关键安全风险因素,并探究安全风险因素间的耦合机制,构建改进N-K模型对装配式建筑施工安全风险进行耦合分析。首先,在现场访谈、专家咨询、政策整理及文献分析的基础上,利用扎根理论建立安全风险指标体系;其次... 为了识别装配式建筑施工的关键安全风险因素,并探究安全风险因素间的耦合机制,构建改进N-K模型对装配式建筑施工安全风险进行耦合分析。首先,在现场访谈、专家咨询、政策整理及文献分析的基础上,利用扎根理论建立安全风险指标体系;其次,运用决策试验与评估实验法(Decision-Making Trial and Evaluation Laboratory, DEMATEL)与熵权法计算主客观权重,基于博弈论组合赋权计算指标综合权重,并以权重替代传统耦合模型中的概率;最后,运用工程实例论证改进N-K模型在装配式建筑施工安全风险因素耦合分析中的适用性及可靠性。结果表明,人员安全意识、现场施工安全管理水平及人员不规范行为是关键安全风险因素,人员因素与管理因素对风险耦合影响较大且五重风险因素的耦合值最大,应重点管控关键安全风险因素,避免多因素风险耦合。 展开更多
关键词 安全工程 装配式建筑 改进n-K模型 博弈论 风险耦合
原文传递
基于N-K和SNA的高层住宅火灾事故风险因素分析及控制 被引量:2
5
作者 武乾 杨建宏 徐树文 《防灾减灾工程学报》 北大核心 2025年第1期128-136,178,共10页
高层住宅火灾安全防控是一个复杂系统问题,从系统层面确定其风险耦合形式及关键风险因素对提升我国高层住宅消防安全水平具有重要意义。为分析高层住宅火灾事故风险因素并提出防控策略,通过收集2015~2023年我国发生的162起高层住宅火灾... 高层住宅火灾安全防控是一个复杂系统问题,从系统层面确定其风险耦合形式及关键风险因素对提升我国高层住宅消防安全水平具有重要意义。为分析高层住宅火灾事故风险因素并提出防控策略,通过收集2015~2023年我国发生的162起高层住宅火灾较大事故案例,结合专家访谈和已有的事故致因分类模型,将高层住宅火灾事故风险因素分为5类一级风险因素和26个二级风险因素;基于N-K模型求解出风险因素耦合值,将风险耦合形式量化并进行耦合致险性评价;利用社会网络分析(Social Network Analysis,SNA)可视化风险因素间的作用关系,分析其中心度和可达性,挖掘出风险因素的发展态势和诱发其他风险因素出现的可能性;结合N-K和SNA对各风险节点的出度进行修正,确定高层住宅火灾事故的关键风险因素。结果表明:多风险因素耦合导致事故发生的概率较大;火灾事故的起因在较大程度上是居民方的原因,开发商、物业、社区、监管单位四方的风险易使灾情扩大、程度升级;防控开发商-监管单位两风险因素耦合可有效避免事故发生;开发商、社区、监管单位风险因素的出现易连通各风险节点,引发耦合效应;从开发商、物业、社区及监管单位角度出发进行防控是重点。 展开更多
关键词 安全工程 高层住宅 火灾事故 n-K模型 社会网络分析 风险耦合
原文传递
Modeling Fiber Fineness, Maturity, and Micronaire in Cotton (Gossypium hirsutum L.) 被引量:3
6
作者 ZHAO Wen-qing ZHOU Zhi-guo +2 位作者 MENG Ya-li CHEN Bing-lin WANG You-hua 《Journal of Integrative Agriculture》 SCIE CAS CSCD 2013年第1期67-79,共13页
Crop performance is determined by the combined effects of the genotype of the crop and the environmental conditions of the production system. This study was undertaken to develop a dynamic model for simulating environ... Crop performance is determined by the combined effects of the genotype of the crop and the environmental conditions of the production system. This study was undertaken to develop a dynamic model for simulating environmental (temperature and solar radiation) and N supply effects on fiber fineness, maturity and micronaire. Three different experiments involving genotypes, sowing dates, and N fertilization rates were conducted to support model development and model evaluation. The growth and development duration of fiber fineness, maturity, and micronaire were scaled by using physiological development time of secondary wall synthesis (PDT SWSP ), which was determined based on the constant ratio of SWSP/ BMP. PTP (product of relative thermal effectiveness (RTE) and photosynthetically active radiation (PAR), MJ m-2) and subtending leaf N content per unit area (N A , g m-2) and critical subtending leaf N content per unit area (CN A , g m-2) of cotton boll were calculated or simulated to evaluate effects of temperature and radiation, and N supply. Besides, the interactions among temperature, radiation and N supply were also explained by piecewise function. The overall performance of the model was calibrated and validated with independent data sets from three field experiments with two sowing dates, three or five flowering dates and three or four N fertilization rates for three subsequent years (2005, 2007, and 2009) at three ecological locations. The average RMSE and RE for fiber fineness, maturity, and micronaire predictions were 372 m g-1 and 5.0%, 0.11 m g-1 and 11.4%, 0.3 m g-1 and 12.3%, respectively, indicating a good fit between the simulated and observed data. It appears that the model can give a reliable prediction for fiber fineness, maturity and micronaire formation under various growing conditions. 展开更多
关键词 simulation model physiological development fiber quality n supply temperature RADIATIOn
在线阅读 下载PDF
装配式建筑施工安全风险因素耦合分析:N-K修正复杂网络
7
作者 窦玉丹 闫学涯 《安全与环境学报》 北大核心 2025年第9期3425-3435,共11页
为定量揭示装配式建筑施工安全风险特性,识别关键风险因素并实现对事故的主动干预,基于N-K模型修正的复杂网络进行风险耦合分析。首先,收集国内外407起事故案例,结合事故致因理论识别出4个子系统与23个风险因素。然后,在宏观角度上通过... 为定量揭示装配式建筑施工安全风险特性,识别关键风险因素并实现对事故的主动干预,基于N-K模型修正的复杂网络进行风险耦合分析。首先,收集国内外407起事故案例,结合事故致因理论识别出4个子系统与23个风险因素。然后,在宏观角度上通过N-K模型分析不同系统间的风险耦合情况,计算风险耦合信息值;在微观角度通过Apriori算法定量挖掘频繁项集,揭示因素间的潜在关联关系,并构建风险因素的复杂网络。最后,基于节点中心度分析与可达性分析,探究风险因素的作用机制,将N-K模型计算值作为权重值,对节点接近中心度值进行耦合修正,识别关键风险因素,并提出针对性的干预建议。结果表明:环-管系统间存在较强的耦合作用,显著增加装配式建筑施工安全事故风险发生的可能性。干预“管理失效”与“人的不安全行为”维度中相关因素有助于减少风险事故发生。同时,现场信息沟通、交叉作业安全和施工自然环境等是导致事故发生的关键因素,需重点防范。 展开更多
关键词 安全工程 装配式建筑 风险因素 n-K模型 复杂网络 耦合分析
原文传递
Assessing productivity and carbon sequestration capacity of subtropical coniferous plantations using the process model PnET-CN
8
作者 YAN Yuan WANG Shaoqiang +4 位作者 WANG Yidong WU Weixing WANG Jingyuan CHEN Bin YANG Fengting 《Journal of Geographical Sciences》 SCIE CSCD 2011年第3期458-474,共17页
A generalized, lumped-parameter ecological model PnET-CN was calibrated and validated for a subtropical coniferous plantation in southern China. PnET-CN model describes the biogeochemical cycles of carbon (C) and ni... A generalized, lumped-parameter ecological model PnET-CN was calibrated and validated for a subtropical coniferous plantation in southern China. PnET-CN model describes the biogeochemical cycles of carbon (C) and nitrogen (N) and can assist in estimating carbon sequestration potential. For validation of PnET-CN, data from coniferous forest plantations in southern China was used. Simulated daily gross primary productivity (GPP) from 2005 to 2007 agreed well with observations (R2=0.56, S.D.=0.009). Simulations of monthly soil respiration (Rs) from 2005-2007 agreed well with Rs observations (R2=0.67, S.D. =0.03). Simu- lated annual net primary productivity (NPP) from 1998-2006 was 803+33 gCm 2a-1, about 4% higher than NPP observation (752+51 gCm-2a-1). Simulations of annual NEP from 2005-2007 only overestimate 9 gCm-2a-1 (4%), 4 gCm 2a-1 (1%) and 34 gCm 2a-1 (8%) compared to NEP observations, respectively. Simulated annual foliar N concentration (FolNCon) (1.09%) is 10% lower than observed monthly FolNCon (0.87%-1.58%). Simulated annual N leaching (0.26 gNm-2) is about 10% lower than leaching observation (0.29 gNm-2). PnET-CN model validation indicates that PnET-CN is capable to simulate daily GPP, annual NPP, annual NEP, monthly Rs, annual FolNCon and annual nitrate N leaching for subtropical coniferous planta- tions in southern China. The results obtained from the validation test revealed that PnET-CN model can be used to simulate carbon sequestration of planted coniferous forests in southern China to a high level of precision. Sensitivity analysis suggests that great care should be taken in developing generalizations as to how forests will respond to a changing climate. PnET-CN performed satisfactorily in comparison to other models that have already been calibrated and validated in coniferous planted subtropical forests in China. Based on PnET-CN validation and its comparison to other models, future improvement of PnET-CN should focus on seasonal foliar N dynamics and the effects of water stress on autotrophic respirations in subtropical coniferous plantations in southern China. 展开更多
关键词 coniferous plantations PnET-Cn model validation foliar n concentration C sequestration
原文传递
融合N-K-DBN模型的船舶自沉事故风险因素动态耦合分析
9
作者 崔秀芳 曾杰熙 +1 位作者 邵志鹏 安楠楠 《安全与环境学报》 北大核心 2025年第6期2080-2091,共12页
我国海上事故频发,当多个风险因素动态耦合时易超系统阈值导致船舶自沉事故,造成人员伤亡、经济损失和环境危害。因此,有必要定量分析影响船舶自沉风险演化特征之间的动态耦合关系,以识别造成事故的关键因素。采用N-K模型和动态贝叶斯网... 我国海上事故频发,当多个风险因素动态耦合时易超系统阈值导致船舶自沉事故,造成人员伤亡、经济损失和环境危害。因此,有必要定量分析影响船舶自沉风险演化特征之间的动态耦合关系,以识别造成事故的关键因素。采用N-K模型和动态贝叶斯网络(Dynamic Bayesian Network, DBN)研究船舶自沉风险因素的动态耦合特性,通过文本挖掘技术分析中国海事局(CMSA)公布的146起船舶自沉事故报告,对风险因素进行分类并探究其耦合机制。首先,利用N-K模型量化各风险因素间的耦合度和关系;然后,利用贝叶斯网络(BN)模型在N-K模型基础上进一步量化和优化了耦合风险,减少其主观性;最后,在BN结构上加入时间序列建立N-K-DBN风险动态耦合模型,通过风险概率分析、敏感性分析、正向推理、反向诊断和不确定性分析等,确定影响动态风险关联性的关键因素及催化因素,实现对航行中耦合风险的动态控制,并提出风险管理策略和防范措施,以提升海上安全。结果表明:船舶自沉事故的发生与耦合值呈正相关,耦合因素越多风险值越高,耦合相互作用越强。事故初期,人为因素和管理因素是船舶自沉事件的关键致因,其交叉耦合时风险更为显著。随着时间推移,船舶因素对事故的影响逐渐提高,更易与人为因素发生交叉耦合导致动态风险增强,而恶劣气象是触发船舶与其他因素耦合的催化因素,易诱发多因素的交叉耦合风险,导致事故发生概率增大。通过研究识别出安全意识淡薄、公司管理不到位、船舶故障、船舶不适航、船舶管理不当和公司未履责等是引发自沉事故的关键动态风险耦合因素,以及恶劣气象这一重要的动态风险耦合催化因素,这些因素须受到高度重视并对它们采取相应防范措施。 展开更多
关键词 安全工程 船舶自沉事故 n-K模型 动态贝叶斯网络 风险动态耦合分析
原文传递
Prediction of efficient outputs based on GM(1,N) model and weak DEA efficiency 被引量:2
10
作者 Jiefang Wang Sifeng Liu 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2011年第6期933-939,共7页
This paper expresses the efficient outputs of decisionmaking unit(DMU) as the sum of "average outputs" forecasted by a GM(1,N) model and "increased outputs" which reflect the difficulty to realize efficient ou... This paper expresses the efficient outputs of decisionmaking unit(DMU) as the sum of "average outputs" forecasted by a GM(1,N) model and "increased outputs" which reflect the difficulty to realize efficient outputs.The increased outputs are solved by linear programming using data envelopment analysis efficiency theories,wherein a new sample is introduced whose inputs are equal to the budget in the issue No.n + 1 and outputs are forecasted by the GM(1,N) model.The shortcoming in the existing methods that the forecasted efficient outputs may be less than the possible actual outputs according to developing trends of input-output rate in the periods of pre-n is overcome.The new prediction method provides decision-makers with more decisionmaking information,and the initial conditions are easy to be given. 展开更多
关键词 efficient outputs GM(1 n model data envelopment analysis(DEA) weak DEA efficiency prediction.
在线阅读 下载PDF
Monte Carlo study of the universal area distribution of clusters in the honeycomb O(n) loop model 被引量:1
11
作者 许亚东 刘清泉 邓友金 《Chinese Physics B》 SCIE EI CAS CSCD 2012年第7期80-84,共5页
We investigate the area distribution of clusters (loops) in the honeycomb O(n) loop model by means of the worm algorithm with n = 0.5, 1, 1.5, and 2. At the critical point, the number of clusters, whose enclosed a... We investigate the area distribution of clusters (loops) in the honeycomb O(n) loop model by means of the worm algorithm with n = 0.5, 1, 1.5, and 2. At the critical point, the number of clusters, whose enclosed area is greater than A, is proportional to A-1 with a proportionality constant C. We confirm numerically that C is universal, and its value agrees well with the predictions based on the Coulomb gas method. 展开更多
关键词 worm algorithm O(n loop model UnIVERSALITY Coulomb gas method
原文传递
基于N-K模型和贝叶斯网络的船舶载运汽车火灾风险耦合分析 被引量:3
12
作者 王意如 王彦富 +1 位作者 乔健 李逊 《消防科学与技术》 北大核心 2025年第4期439-447,共9页
风险之间由于传播效应和相互作用而产生的风险因素耦合,可能导致重大事故的发生。为了分析船舶载运汽车火灾事故风险的耦合性,提出N-K模型和贝叶斯网络(BN)模型相结合的一种新的定量分析方法。首先,通过对历史事故的统计分析,探讨船舶... 风险之间由于传播效应和相互作用而产生的风险因素耦合,可能导致重大事故的发生。为了分析船舶载运汽车火灾事故风险的耦合性,提出N-K模型和贝叶斯网络(BN)模型相结合的一种新的定量分析方法。首先,通过对历史事故的统计分析,探讨船舶载运汽车火灾事故的原因,明确人员、机械、电气和环境因素的风险耦合类型;其次,构建N-K模型研究各因素之间的耦合关系和风险耦合机制;最后,根据上述结果构建BN模型并验证。此外,我们还将开展敏感性分析和反向推理分析等深入研究,以确保模型的准确性。结果表明:船舶载运汽车发生火灾概率最高的耦合类型是“人员-机械”耦合,发生概率为14.795%;发生火灾概率最低的是“人员-机械-电气-环境”耦合,发生率为1.354%,但其风险耦合值最大,约为0.43。我们应当特别关注与人员操作和机械故障相关的风险因素,以预防这些因素的共存或多重叠加,进而有效降低船舶载运汽车火灾事故的发生,本研究的成果不仅对提升船舶载运汽车的防火规范具有指导意义,同时也为风险评估和消防救援工作提供了参考依据。 展开更多
关键词 船舶载运汽车火灾 风险耦合分析 Bn模型 n-K模型
在线阅读 下载PDF
Analysis of a multi-patch dynamical model about cattle brucellosis 被引量:1
13
作者 Juan Zhang Shigui Ruan +2 位作者 Guiquan Sun Xiangdong Sun Zhen Jin 《上海师范大学学报(自然科学版)》 2014年第5期441-455,共15页
The dissemination of cattle brucellosis in Zhejiang province of China can be attributed to the transport of cattle between cities within the province. In this paper,an n-patch dynamical model is proposed to study the ... The dissemination of cattle brucellosis in Zhejiang province of China can be attributed to the transport of cattle between cities within the province. In this paper,an n-patch dynamical model is proposed to study the effect of cattle dispersal on brucellosis spread. Theoretically,we analyze the dynamical behavior of the muti-patch model. For the 2-patch submodel,sensitivity analyses of the basic reproduction number R0 and the number of the infectious cattle in term of model parameters are carried out. By numerical analysis,it is obtained that the dispersal of susceptible cattle between patches and the centralization of infected cattle to the large scale patch can alleviate the epidemic and are in favor of the control of disease in the whole region. 展开更多
关键词 BRUCELLOSIS CATTLE n-patch model dispersal
在线阅读 下载PDF
Incorporating Linguistic Rules in Statistical Chinese Language Model for Pinyin-to-character Conversion 被引量:2
14
作者 刘秉权 Wang +2 位作者 Xiaolong Wang Yuying 《High Technology Letters》 EI CAS 2001年第2期8-13,共6页
An N-gram Chinese language model incorporating linguistic rules is presented. By constructing elements lattice, rules information is incorporated in statistical frame. To facilitate the hybrid modeling, novel methods ... An N-gram Chinese language model incorporating linguistic rules is presented. By constructing elements lattice, rules information is incorporated in statistical frame. To facilitate the hybrid modeling, novel methods such as MI-based rule evaluating, weighted rule quantification and element-based n-gram probability approximation are presented. Dynamic Viterbi algorithm is adopted to search the best path in lattice. To strengthen the model, transformation-based error-driven rules learning is adopted. Applying proposed model to Chinese Pinyin-to-character conversion, high performance has been achieved in accuracy, flexibility and robustness simultaneously. Tests show correct rate achieves 94.81% instead of 90.53% using bi-gram Markov model alone. Many long-distance dependency and recursion in language can be processed effectively. 展开更多
关键词 Chinese Pinyin-to-character conversion Rule-based language model n-gram language model Hybrid language model Element lattice Transformation-based error-driven learning
在线阅读 下载PDF
A Process-based Model of N_2O Emission from a Rice-Winter Wheat Rotation Agro-Ecosystem:Structure,Validation and Sensitivity 被引量:1
15
作者 周再兴 郑循华 +2 位作者 谢宝华 韩圣慧 刘春岩 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2010年第1期137-150,共14页
In order to numerically simulate daily nitrous oxide (N2O) emission from a rice-winter wheat rotation cropping system, a process-based site model was developed (referred to as IAP-N-GAS) to track the movement and ... In order to numerically simulate daily nitrous oxide (N2O) emission from a rice-winter wheat rotation cropping system, a process-based site model was developed (referred to as IAP-N-GAS) to track the movement and transformation of several forms of nitrogen in the agro-eeosystem, which is affected by climate, soil, crop growth and management practices. The simulation of daily N2O fluxes, along with key daily environmental variables, was validated with three-year observations conducted in East China. The validation demonstrated that the model simulated well daily solar radiation, soil temperature and moisture, and also captured the dynamics and magnitude of accumulated rice aboveground biomass and mineral nitrogen in the soil. The simulated daily N2O emissions over all three years investigated were generally in good agreement with field observations. Particularly well simulated were the peak N2O emissions induced by fertilizations, rainfall events or mid-season drainages. The model simulation also represented closely the inter-annuM variation in N2O emission. These validations imply that the model has the capability to capture the general characteristics of N2O emission from a typical rice-wheat rotation agro-ecosystem. Sensitivity analyses revealed that the simulated N2O emission is most sensitive to the fertilizer application rate and the soil organic matter content, but it is much less sensitive to variations in soil pH and texture, temperature, precipitation and crop residue incorporation rate under local conditions. 展开更多
关键词 nitrous oxide n2O) modeling n cycling rice-wheat rotation
在线阅读 下载PDF
基于STL分解与N-BEATS的铁路货运站短期装车量组合预测模型 被引量:1
16
作者 马亮 陈奕霖 +2 位作者 郭进 胡宸瀚 金福才 《中国铁道科学》 北大核心 2025年第3期216-228,共13页
针对铁路货运站短期装车量的波动性与随机性特征导致其时序特征较难提取的问题,提出基于STL分解方法与N-BEATS神经网络模型的组合预测模型STL-N-BEATS。先通过STL分解方法将原始数据分解为趋势序列、周期序列和剩余项序列,再利用N-BEAT... 针对铁路货运站短期装车量的波动性与随机性特征导致其时序特征较难提取的问题,提出基于STL分解方法与N-BEATS神经网络模型的组合预测模型STL-N-BEATS。先通过STL分解方法将原始数据分解为趋势序列、周期序列和剩余项序列,再利用N-BEATS模型对各分量分别建模并重构预测结果,最后基于某铁路运输企业的4个货运站546 d的历史装车数据,对比所提模型与其他6种模型的预测性能。结果表明:A站测试集下,其他6种模型的预测均有一定滞后性,而所提模型可以较好地拟合真实值曲线,计算得到的对称平均绝对百分比误差、平均绝对误差和均方根误差3项指标均最低,这是由于所提模型分解时序特征后得到的趋势序列和周期序列主导了预测结果,降低了整体数据的不确定性和波动性;预测步长分别为3和7 d时,在B,C,D这3个货运站日装车量预测和D站不同去向、不同品名日装车量预测场景下,所提模型的3项指标仍均最低,标志着其具有良好的预测性能和泛化能力。 展开更多
关键词 铁路货运 短期装车量预测 深度学习 STL分解方法 n-BEATS模型
在线阅读 下载PDF
Optimizing Parameters of CSM-CERES-Maize Model to Improve Simulation Performance of Maize Growth and Nitrogen Uptake in Northeast China 被引量:15
17
作者 LIU Hai-long YANG Jing-yi +9 位作者 HE Ping BAI You-lu JIN Ji-yun Craig F Drury ZHU Ye-ping YANGXue-ming LI Wen-juan XIE Jia-gui YANG Jing-min Gerrit Hoogenboom 《Journal of Integrative Agriculture》 SCIE CAS CSCD 2012年第11期1898-1913,共16页
Crop models can be useful tools ibr optimizing fertilizer management for a targeted crop yield while minimizing nutrient losses. In this paper, the parameters of the decision support system for agrotechnology transfer... Crop models can be useful tools ibr optimizing fertilizer management for a targeted crop yield while minimizing nutrient losses. In this paper, the parameters of the decision support system for agrotechnology transfer (DSSAT)-CERES-Maize were optimized using a new method to provide a better simulation of maize (Zea mays L.) growth and N upfake in response to different nitrogen application rates. Field data were collected from a 5 yr field experiment (2006-2010) on a Black soil (Typic hapludoll) in Gongzhuling, Jilin Province, Northeast China. After cultivar calibration, the CERES-Maize model was able to simulate aboveground biomass and crop yield of in the evaluation data set (n-RMSE=5.0-14.6%), but the model still over-estimated aboveground N uptake (i.e., with E values from -4.4 to -21.3 kg N ha-~). By analyzing DSSAT equation, N stress coefficient for changes in concentration with growth stage (CTCNP2) is related to N uptake. Further sensitivity analysis of the CTCNP2 showed that the DSSAT model simulated maize nitrogen uptake more precisely after the CTCNP2 coefficient was adjusted to the field site condition. The results indicated that in addition to calibrating 6 coefficients of maize cultivars, radiation use efficiency (RUE), growing degree days for emergence (GDDE), N stress coefficient, CTCNP2, and soil fertility factor (SLPF) also need to be calibrated in order to simulate aboveground biomass, yield and N uptake correctly. Independent validation was conducted using 2008-2010 experiments and the good agreement between the simulated and the measured results indicates that the DSSAT CERES-Maize model could be a useful tool for predicting maize production in Northeast China. 展开更多
关键词 DSSAT CERES-Maize model maize growth simulation model evaluation fertilizer n experiment
在线阅读 下载PDF
Phase Transitions of a Dilute O(n) Model
18
作者 GUOWen-An HenkW.J.B1ote LIUYuan-Yuan 《Communications in Theoretical Physics》 SCIE CAS CSCD 2004年第6期911-916,共6页
We investigate tricritical behavior of the O(n) model in two dimensions by means of transfer-matrix and finite-size scaling methods. For this purpose we consider an O(n) symmetric spin model on the honeycomb lattice w... We investigate tricritical behavior of the O(n) model in two dimensions by means of transfer-matrix and finite-size scaling methods. For this purpose we consider an O(n) symmetric spin model on the honeycomb lattice with vacancies; the tricritical behavior is associated with the percolation threshold of the vacancies. The vacancies are represented by face variables on the elementary hexagons of thelattice. We apply a mapping of the spin degrees of freedom model on a non-intersecting-loop model, in which the number n of spin components assumes the role of a continuously variable parameter. This loop model serves as a suitable basis for the construction of the transfer matrix.Our results reveal the existence of a tricritical line, parametrized by n, which connects the known universality classes of the tricritical Ising model and the theta point describing the collapse of a polymer. On the other side of theIsing point,the tricritical line extends to the n = 2 point describing a tricritical O(2) model. 展开更多
关键词 phase transition dilute O(n) model tricritical behavior transfer matrix
在线阅读 下载PDF
A Preliminary Study on Dynamics and Models of N,P,K Absorption for High-Yield Cotton 被引量:6
19
作者 WANGKe-ru LIShao-kun +3 位作者 CAOLian-pu SONGGuang-jie CHENGang CAOSuan-zhu 《Agricultural Sciences in China》 CAS CSCD 2003年第7期752-759,共8页
The field experiments were carried out to investigate the dynamics and models of N, P and K absorption for the cotton plants with a lint of 3 000 kg ha-1 in Xinjiang. The main results were as follows: The contents of ... The field experiments were carried out to investigate the dynamics and models of N, P and K absorption for the cotton plants with a lint of 3 000 kg ha-1 in Xinjiang. The main results were as follows: The contents of N, P2O5, K2O in cotton leaves, stems, squares and bolls decreased obviously with the time over the whole growth duration and the falling extent was greater in high-yield cotton than in CK. Contents of N in leaves, squares and bolls, in particular in the leaves of fruit-bearing shoot was higher in high-yield cotton than in CK. Contents of P2O5 in squares and bolls and that of K2O in stems were higher in high-yield cotton than in CK during the whole growing period. The accumulations of N, P2O5 and K2O in the cotton plants could be described with a logistic curve equation. There was the fastest nutrient uptake at about 90 d for N, 92 d for P2O5 and 85 d for K2O after emergence, respectively. Total nutrient accumulation of N, P2O5 and K2O was 385.8, 244. 7 and 340.3 kg ha-1, respectively. Approximately 12. 5 kg N, 8. 0 kg P2O5 and 11.1 kg K2O were needed for producing 100 kg lint with the leaves and stems under the super high yield condition of 3 000 kg ha-1 in Xinjiang. 展开更多
关键词 XInJIAnG Cultivation of high yield COTTOn n P K Absorption dynamics model
在线阅读 下载PDF
Heterogeneity in song rates in the Collared Flycatcher(Ficedula albicollis)explained with the availability parameter in generalized N-mixture models:Its importance for abundance estimates in avian aural counts
20
作者 Grzegorz Neubauer Arkadiusz Sikora 《Avian Research》 SCIE CSCD 2023年第1期38-44,共7页
Binomial N-mixture models are commonly applied to estimate abundance unaffected by imperfect detection,but are known to be sensitive to violations of assumptions.One of the model’s assumptions,the independence of det... Binomial N-mixture models are commonly applied to estimate abundance unaffected by imperfect detection,but are known to be sensitive to violations of assumptions.One of the model’s assumptions,the independence of detections has rarely been tested.It requires that during a survey,detection of one individual does not affect detection of another individual.This assumption can be frequently violated in passerine birds,which exhibit territorial behaviour by singing,since neighbouring individuals are likely to motivate each other to vocalize,leading to non-independence in singing activity and in the following detection rate.Here,we explored this phenomenon with the generalized,binomial version of the N-mixture model,where detection probability is decomposed into availability probability φ-which can be interpreted as per capita song rate or the probability of vocalising-and actual detection probability p,given vocalisations take place.Using repeated counts of the Collared Flycatcher(Ficedula albicollis)as a case study,and treating the maximum observed counts C_(maxi) at a site i as an explanatory covariate for φ,we showed that per capita song rates increased with observed counts at a site.Hence,if song rates vary due to local abundance,including C_(maxi)as an explanatory variable for song rate addressed with φ,helps to explain this variation(which otherwise goes undetected)and improves inferences under the model.This had strong effects on the resulting abundance estimates:if this relationship was ignored in the models,total estimated population sizes were consequently lower by as much as 22-27%,compared to when this effect was included.Since it is likely that song rates may commonly be density-dependent in birds manifesting territorial behaviours by singing,further tests addressing violations of independence assumptions in these models are needed.As suggested by Kery and Royle(2016),despite some form of circularity likely being involved,modelling heterogeneity in the detection process with the help of C_(maxi)in standard N-mixture models(which,given availability,conflate availability with detection in a single parameter)should be applicable as well. 展开更多
关键词 ABUnDAnCE Awailabity Bird∞mt Dansity dpendent detection Ganerlizd n minture models Singing sactiwity Song Tate
在线阅读 下载PDF
上一页 1 2 101 下一页 到第
使用帮助 返回顶部