期刊文献+
共找到318篇文章
< 1 2 16 >
每页显示 20 50 100
Pattern Recognition for Flank Eruption Forecasting: An Application at Mount Etna Volcano (Sicily, Italy)
1
作者 A. Brancato P. M. Buscema +1 位作者 G. Massini S. Gresta 《Open Journal of Geology》 2016年第7期583-597,共16页
A volcano can be defined as a complex system, not least for the hidden clues related to its internal nature. Innovative models grounded in the Artificial Sciences, have been proposed for a novel pattern recognition an... A volcano can be defined as a complex system, not least for the hidden clues related to its internal nature. Innovative models grounded in the Artificial Sciences, have been proposed for a novel pattern recognition analysis at Mt. Etna volcano. The reference monitoring dataset dealt with real data of 28 parameters collected between January 2001 and April 2005, during which the volcano underwent the July-August 2001, October 2002-January 2003 and September 2004-April 2005 flank eruptions. There were 301 eruptive days out of an overall number of 1581 investigated days. The analysis involved successive steps. First, the TWIST algorithm was used to select the most predictive attributes associated with the flank eruption target. During his work, the algorithm TWIST selected 11 characteristics of the input vector: among them SO<sub>2</sub> and CO<sub>2</sub> emissions, and also many other attributes whose linear correlation with the target was very low. A 5 × 2 Cross Validation protocol estimated the sensitivity and specificity of pattern recognition algorithms. Finally, different classification algorithms have been compared to understand if this pattern recognition task may have suitable results and which algorithm performs best. Best results (higher than 97% accuracy) have been obtained after performing advanced Artificial Neural Networks, with a sensitivity and specificity estimates over 97% and 98%, respectively. The present analysis highlights that a suitable monitoring dataset inferred hidden information about volcanic phenomena, whose highly non-linear processes are enhanced. 展开更多
关键词 Mt. Etna Volcano Flank Eruption forecasting Neural Networks pattern Recognition Monitoring Data
暂未订购
LSTM和EnKF在农业土壤降雨径流模拟中的应用
2
作者 林琳 高肇天 +2 位作者 丁一家 胡小龙 张中彬 《湖北农业科学》 2025年第5期70-79,共10页
降雨量与径流的关系对农业地区的水资源调配及水土资源保护具有重要意义,但在小流域范围内,不同土地利用类型下降雨径流过程难以预测。基于LSTM模型、新安江模型以及EnKF技术,探讨数据驱动机器学习模型对不同土地利用方式下降雨径流过... 降雨量与径流的关系对农业地区的水资源调配及水土资源保护具有重要意义,但在小流域范围内,不同土地利用类型下降雨径流过程难以预测。基于LSTM模型、新安江模型以及EnKF技术,探讨数据驱动机器学习模型对不同土地利用方式下降雨径流过程的模拟效果,并与SWAT水文模型模拟效果进行对比;研究EnKF对新安江模型不同水文参数集合的估计效果和滤波估计参数的规律,并基于率定的参数对不同农业土地利用类型的径流过程进行模拟。结果表明,径流在土面坡度略小时的高径流情况以及在土面坡度较大时的低径流过程更易被学习到;SWAT模型模拟精度及稳定性比LSTM模型差,但其可以在一定程度反映当地土壤水文条件,便于进行成因分析;EnKF技术具有参数更新和参数估计功能,能够优化新安江水文模型的径流模拟效果。 展开更多
关键词 降雨径流模拟 数据驱动 数据同化 LSTM ENKF 新安江模型 土地利用方式 优化预测
在线阅读 下载PDF
机器学习算法在ICU患者压力性损伤风险预警中的应用进展 被引量:3
3
作者 冀慧敏 柏亚妹 +3 位作者 宋玉磊 张薛晴 徐桂华 王晓凤 《护理学杂志》 北大核心 2025年第5期126-128,F0003,共4页
综述机器学习算法在ICU压力性损伤风险预警中的应用,预测模型包括逻辑回归模型、基于树的模型、决策树模型、贝叶斯算法、循环神经网络及集成模型,旨在为制订个性化的预防策略提供科学方法,以提升ICU护理水平。
关键词 ICU 压力性损伤 机器学习算法 模式识别 预测分析 逻辑回归 基于树的模型 风险预警
暂未订购
我国短时强降水研究进展
4
作者 赵强 郑永光 +2 位作者 井宇 冯典 刘菊菊 《地球科学进展》 北大核心 2025年第1期21-38,共18页
短时强降水是我国最主要的强对流灾害天气之一,易造成城市内涝和山洪、泥石流以及滑坡等次生地质灾害。回顾了近年来我国短时强降水的主要研究进展,并简要对比了美国和欧洲的相关研究成果,涵盖了短时强降水的时空分布特征、大气环流形... 短时强降水是我国最主要的强对流灾害天气之一,易造成城市内涝和山洪、泥石流以及滑坡等次生地质灾害。回顾了近年来我国短时强降水的主要研究进展,并简要对比了美国和欧洲的相关研究成果,涵盖了短时强降水的时空分布特征、大气环流形势和环境条件、雷达回波特征和雨滴谱特征以及地形和城市化对短时强降水的影响及其机制;总结了人工智能在我国短时强降水潜势预报和短时临近预报中的应用。随着全球变暖,短时强降水频次和强度都呈增加趋势,今后需要进一步研究其形成机制和环境条件,提升观测时空分辨率,加强新型观测资料应用,通过融合分析多源且稠密的观测资料,提升高分辨率的快速更新循环同化数值模式预报能力,改进和发展深度学习预报模型和算法,尤其是研发深度学习大模型来提升短时强降水的预报预警能力。 展开更多
关键词 短时强降水 日变化 环流分型 雨滴谱 热岛效应 客观预报方法
原文传递
区域中心城市市域“三生”功能演变与模拟研究——以南京市为例
5
作者 杜小娅 杨欣蕾 方斌 《南京师大学报(自然科学版)》 北大核心 2025年第4期14-25,共12页
中心城市是区域社会经济发展的增长极,其对周边地区生产、生活、生态功能协同提升的示范作用至关重要.本文以长三角中心城市南京市为例,构建“三生”功能评价指标体系,测算2012—2022年的“三生”功能;利用地理探测器模型识别功能演变... 中心城市是区域社会经济发展的增长极,其对周边地区生产、生活、生态功能协同提升的示范作用至关重要.本文以长三角中心城市南京市为例,构建“三生”功能评价指标体系,测算2012—2022年的“三生”功能;利用地理探测器模型识别功能演变的影响因素;借助空间自相关模型探索生产、生活、生态功能间的权衡/协同关系;运用PLUS模型预测2032年的南京市“三生”功能格局,提出格局优化策略.主要结果包括:①南京市“三生”功能整体存在退化现象,生态功能高值区的大幅减少是其主导原因.②“三生”功能间存在较大范围的低低协同区,仅生产—生态功能间的高高协同区面积较大,“三生”功能的同步提升成为功能格局优化关键.③“三生”功能演变整体受社会经济因素的影响较强,土地开发强度、GDP和城镇化水平始终是功能演变的主导因子.④自然发展情境下,2032年南京市“三生”功能高值区显著退化,但市域主城区及其周边的综合功能有所提升.本文认为市域综合功能薄弱区的“三生”功能全面提升、主城区的生态功能优化、乡村地区的生活功能提升和生态功能维持是南京市“三生”功能格局优化的重要方向. 展开更多
关键词 “三生”功能 权衡/协同 模拟预测 格局优化 南京市
在线阅读 下载PDF
基于PowerTimeMixer模型的短期电力负荷预测方法
6
作者 李裕民 李宏杰 +3 位作者 李晓嘉 曹媛媛 谢毅 张超 《电网技术》 北大核心 2025年第10期4216-4227,I0058,共13页
文章针对现有电力负荷预测方法未能充分捕获电力负荷数据的周期性和趋势性特性导致预测稳定性差的问题,提出了一种短期电力负荷预测模型PowerTimeMixer。首先,基于解耦思想对原始时间序列进行时序分解,并以多尺度方式学习时序的周期和... 文章针对现有电力负荷预测方法未能充分捕获电力负荷数据的周期性和趋势性特性导致预测稳定性差的问题,提出了一种短期电力负荷预测模型PowerTimeMixer。首先,基于解耦思想对原始时间序列进行时序分解,并以多尺度方式学习时序的周期和趋势特性;其次,引入卷积下采样机制并通过网络参数共享来匹配循环周期,进一步增强电力负荷数据周期模式的特征提取能力;最后,采用独立的日期模式驱动预测模块,使用多层感知机对输入序列和目标序列时间戳特征进行编码,独立地学习时间戳特征,引导网络根据时间戳特征生成更稳定的预测结果。在电力负荷数据集上的实验结果表明,所提出的方法相比基准模型的预测误差显著降低,具有更稳定的预测性能,从而验证了方法的有效性。 展开更多
关键词 电力负荷预测 时序分解 多尺度解耦 日期模式驱动预测 多层感知机
原文传递
基于CNN-GRU-BP网络的急弯航道表面碍航流态特征预报方法研究
7
作者 刘振嘉 任伯浩 +2 位作者 梁锴 王雪蓉 李明伟 《水运工程》 2025年第6期158-166,共9页
针对急弯航道碍航流态通航安全风险问题,为理清不同种类典型碍航流态的发生规律,基于已知的客观条件对未来可能发生的典型碍航流态进行预报,对不同流态特征进行重点归纳和梳理,并进行了急弯航道表面流态特征预测方法研究。采用基于CNN-G... 针对急弯航道碍航流态通航安全风险问题,为理清不同种类典型碍航流态的发生规律,基于已知的客观条件对未来可能发生的典型碍航流态进行预报,对不同流态特征进行重点归纳和梳理,并进行了急弯航道表面流态特征预测方法研究。采用基于CNN-GRU-BP组合神经网络的预测方法,并与实测值和传统数值方法进行了对比验证。结果表明:组合网络预报方法对航道表面流态特征具备较好的预测性能,能够实时、精确、有针对性地得到在输入的非线性影响因素下不同流态的特征值,对实际航道的通航安全管控提供了数据支持,为防范化解相关通航安全风险提供了技术支撑。 展开更多
关键词 表面流态 预报模型 神经网络 通航安全
在线阅读 下载PDF
TRIZ TECHNOLOGY FORECASTING AS QFD INPUT WITHIN THE NPD ACTIVITIES 被引量:16
8
作者 CoulibalySolomani HuaZhongsheng +1 位作者 ShiQin WangWei 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2004年第2期284-288,共5页
As a result of the fierceness of business competition, companies, to remaincompetitive, have to charm their customers by anticipating their needs and being able to rapidlydevelop exciting new products for them. To ove... As a result of the fierceness of business competition, companies, to remaincompetitive, have to charm their customers by anticipating their needs and being able to rapidlydevelop exciting new products for them. To overcome this challenge, technology forecasting isconsidered as a powerful tool in today's business environment, while there are as many successstories as there are failures, a good application of this method will give a good result. Amethodology of integration of patterns or lines of technology evolution in TRIZ parlance ispresented, which is also known as TRIZ technology forecasting, as input to the QFD process to designa new product. For this purpose, TRIZ technology forecasting, one of the TRIZ major tools, isdiscussed and some benefits compared to the traditional forecasting techniques are highlighted. Thena methodology to integrate TRIZ technology forecasting and QFD process is highlighted. 展开更多
关键词 Theory of inventive problem solving (TRIZ) Quality function deployment(QFD) Technology forecasting patterns/lines of technology evolution
在线阅读 下载PDF
郴州市市域铁路网高质量发展规划研究
9
作者 石若琳 《铁道勘测与设计》 2025年第3期40-44,共5页
为实现新时代铁路先行发展新格局下郴州综合交通高质量发展,融入交通强国建设大局,立足郴州铁路网发展现状及关键诉求,对郴州市域铁路网规划布局方案进行系统研究。首先,对目前郴州市域铁路网布局结构、路网规模、运营概况和运输能力适... 为实现新时代铁路先行发展新格局下郴州综合交通高质量发展,融入交通强国建设大局,立足郴州铁路网发展现状及关键诉求,对郴州市域铁路网规划布局方案进行系统研究。首先,对目前郴州市域铁路网布局结构、路网规模、运营概况和运输能力适应性等方面进行研究,分析目前郴州市域铁路网发展存在的问题;接着,基于郴州市铁路客货运输需求预测结果,提出郴州市域铁路网规划思路、规划目标和规划方案。研究表明,郴州市将以“通达东西、优化南北、健全枢纽、完善支线”战略总体构想,规划形成人悦其行、物畅其流的现代化综合交通运输网络。 展开更多
关键词 铁路网规划 线网布局 运输需求 客货运量预测 高质量发展
在线阅读 下载PDF
双循环新发展格局下成都航空物流需求预测研究
10
作者 黄俊 《成都航空职业技术学院学报》 2025年第3期67-72,110,共7页
双循环新发展格局为成都航空物流发展带来了机遇与挑战,基于2016-2023年成都航空物流数据,选择灰色GM(1,1)模型和二次指数平滑方法分别得到两种单项预测结果,通过引入有序加权几何平均算子(IOWGA),结合灰色GM(1,1)模型和二次指数平滑方... 双循环新发展格局为成都航空物流发展带来了机遇与挑战,基于2016-2023年成都航空物流数据,选择灰色GM(1,1)模型和二次指数平滑方法分别得到两种单项预测结果,通过引入有序加权几何平均算子(IOWGA),结合灰色GM(1,1)模型和二次指数平滑方法构建成都航空物流组合预测模型,对比组合预测模型与两种单项预测结果的误差数据后发现,运用IOWGA的组合预测对成都航空物流需求的预测精度更高,同时借助该组合预测模型完成了2024-2028年成都航空物流需求的预测。 展开更多
关键词 双循环 新发展格局 成都航空物流 需求预测研究
在线阅读 下载PDF
Simulation and Projection of Monso on Rainfall and Rain Patterns over Eastern China under Global Warming by RegCM3 被引量:15
11
作者 Filippo GIORGI 《Atmospheric and Oceanic Science Letters》 2009年第5期308-313,共6页
The authors investigate possible changes of monsoon rainfall and associated seasonal (June-JulyAugust) anomaly patterns over eastern China in the late 21st century under the Intergovernmental Panel on Climate Change (... The authors investigate possible changes of monsoon rainfall and associated seasonal (June-JulyAugust) anomaly patterns over eastern China in the late 21st century under the Intergovernmental Panel on Climate Change (IPCC) Special Report on Emission Scenarios (SRES) A2 emission scenario as simulated by a high-resolution regional climate model (RegCM3) nested in a general circulation model (FvGCM/CCM3).Two sets of multi-decadal simulations are performed at 20-km grid spacing for present day and future climate conditions.Results show that the RegCM3 reproduces the mean rainfall distribution;however the evolution of the monsoon rain belt from South China to North China is not well simulated.Concerning the rain pattern classifications,RegCM3 overestimates the occurrence of Pattern 1 (excessive rainfall in northern China) and underestimates that of Pattern 2 (increased rainfall over the Huai River basin).Under future climate conditions,RegCM3 projects less occurrence of Pattern 1,more of Pattern 2,and little change of Pattern 3 (rainfall increase along the Yangtze River).These results indicate that there might be increased rainfall over the Huai-Yellow River area and reduced rainfall over North China in the future,while rainfall over the lower reaches of the Yangtze River basin is not modified significantly.Uncertainties exist in the present study are also discussed. 展开更多
关键词 CLIMATE change seasonal forecast MONSOON RAIN patternS regional CLIMATE model eastern China
在线阅读 下载PDF
基于模糊聚类软划分法的广东省典型流域设计雨型研究
12
作者 左斌斌 谭超 +3 位作者 程涛 钟伟强 刘志敏 李泽君 《水利水电技术(中英文)》 北大核心 2025年第9期108-117,共10页
【目的】设计雨型作为无资料地区计算设计洪水的重要组成部分之一,对设计洪水的洪峰流量和时程分配具有显著影响。随着气候变化的影响,原有的雨型可能发生变化,需要通过延长水文序列,来进一步研究雨型的变化情况。【方法】采用Mann-Kend... 【目的】设计雨型作为无资料地区计算设计洪水的重要组成部分之一,对设计洪水的洪峰流量和时程分配具有显著影响。随着气候变化的影响,原有的雨型可能发生变化,需要通过延长水文序列,来进一步研究雨型的变化情况。【方法】采用Mann-Kendall趋势检验法和模糊聚类软划分法,选取广东省内的4个典型流域,涉及12个雨量站点的年最大24 h和72 h的降雨过程作为研究对象。基于指标体系构建模糊等价矩阵,运用模糊聚类法计算得出不同历时下的设计雨型。【结果】结果表明:年最大24 h和72 h的降雨量在洞冠水流域呈现出增加的趋势,白芒站年最大24 h降雨量变化速率最大,为0.96 mm/a;而在榕江北河流域则呈现出减少的趋势,富口站年最大72 h降雨量变化速率为-1.25 mm/a。同时,各典型流域的设计雨型均呈现出复合型雨峰的特点,且主雨峰在总降雨量中的占比没有明显差异,主要不同体现在降雨的时程分配上。【结论】与《广东省暴雨径流查算图表使用手册》中的设计雨型相比,主雨峰的控制时段发生了改变。研究结果不仅可为典型流域的设计洪水计算提供有价值的参考,同时也为无资料地区的暴雨雨型研究提供思路。 展开更多
关键词 广东省 模糊聚类软划分法 降雨 Mann-Kendall趋势检验 设计雨型 气候变化 无资料地区暴雨雨型 洪水预报
在线阅读 下载PDF
Geostatistical Analysis on the Temporal Patterns of the Yellow Rice Borer, Tryporyza incertulas 被引量:2
13
作者 YUAN Zhe-ming WANG Zhi Hu Xiang-yue 《Rice science》 SCIE 2005年第3期207-212,共6页
In order to comprehend temporal pattern of the larvae population of the yellow rice borer, Tryporyza incertulas, and provide valuable information for its forecast model, the data series of the population for each gene... In order to comprehend temporal pattern of the larvae population of the yellow rice borer, Tryporyza incertulas, and provide valuable information for its forecast model, the data series of the population for each generation and the over-wintered larvae from 1960 to 1990 in Dingcheng District, Changde City, Hunan Province, were analyzed with geostatistics. The data series of total number, the 1st generation, the 3rd generation and the over-wintered larvae year to year displayed rather better autocorrelation and prediction. The data series of generation to generation, the 2nd generation and the 4th generation year to year, however, demonstrated poor autocorrelation, especially for the 4th generation, whose autocorrelation degree was zero. The population dynamics of the yellow rice borer was obviously intermittent. A remarkable cycle of four generations, one year, was observed in the population of generation to generation. Omitting the certain generation or interposing the over-wintered larvae only resulted in a less or slight change of autocorrelation of the whole data series generation to generation. Crop system, food, climate and natural enemies, therefore, played more important roles in regulating the population dynamics than base number of the larvae. The basic techniques of geostatistics applied in analyzing temporal population dynamics were outlined. 展开更多
关键词 Tryporyza incertulas GEOSTATISTICS temporal patterns POPULATION forecast
在线阅读 下载PDF
Technical Note on a Track-pattern-based Model for Predicting Seasonal Tropical Cyclone Activity over the Western North Pacific 被引量:1
14
作者 Chang-Hoi HO Joo-Hong KIM +5 位作者 Hyeong-Seog KIM Woosuk CHOI Min-Hee LEE Hee-Dong YOO Tae-Ryong KIM Sangwook PARK 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2013年第5期1260-1274,共15页
Recently, the National Typhoon Center (NTC) at the Korea Meteorological Administration launched a track-pattern-based model that predicts the horizontal distribution of tropical cyclone (TC) track density from Jun... Recently, the National Typhoon Center (NTC) at the Korea Meteorological Administration launched a track-pattern-based model that predicts the horizontal distribution of tropical cyclone (TC) track density from June to October. This model is the first approach to target seasonal TC track clusters covering the entire western North Pacific (WNP) basin, and may represent a milestone for seasonal TC forecasting, using a simple statistical method that can be applied at weather operation centers. In this note, we describe the procedure of the track-pattern-based model with brief technical background to provide practical information on the use and operation of the model. The model comprises three major steps. First, long-term data of WNP TC tracks reveal seven climatological track clusters. Second, the TC counts for each cluster are predicted using a hybrid statistical-dynamical method, using the seasonal prediction of large-scale environments. Third, the final forecast map of track density is constructed by merging the spatial probabilities of the seven clusters and applying necessary bias corrections. Although the model is developed to issue the seasonal forecast in mid-May, it can be applied to alternative dates and target seasons following the procedure described in this note. Work continues on establishing an automatic system for this model at the NTC. 展开更多
关键词 tropical cyclone western North Pacific seasonal forecast track-pattern-based model hybrid statistical-dynamical approach
在线阅读 下载PDF
Predictable and Unpredictable Components of the Summer East Asia–Pacific Teleconnection Pattern 被引量:3
15
作者 Xiaozhen LIN Chaofan LI +1 位作者 Riyu LU Adam A.SCAIFE 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2018年第11期1372-1380,共9页
The East Asia–Pacific(EAP) teleconnection pattern is the dominant mode of circulation variability during boreal summer over the western North Pacific and East Asia, extending from the tropics to high latitudes. Howev... The East Asia–Pacific(EAP) teleconnection pattern is the dominant mode of circulation variability during boreal summer over the western North Pacific and East Asia, extending from the tropics to high latitudes. However, much of this pattern is absent in multi-model ensemble mean forecasts, characterized by very weak circulation anomalies in the mid and high latitudes. This study focuses on the absence of the EAP pattern in the extratropics, using state-of-the-art coupled seasonal forecast systems. The results indicate that the extratropical circulation is much less predictable, and lies in the large spread among different ensemble members, implying a large contribution from atmospheric internal variability. However,the tropical–mid-latitude teleconnections are also relatively weaker in models than observations, which also contributes to the failure of prediction of the extratropical circulation. Further results indicate that the extratropical EAP pattern varies closely with the anomalous surface temperatures in eastern Russia, which also show low predictability. This unpredictable circulation–surface temperature connection associated with the EAP pattern can also modulate the East Asian rainband. 展开更多
关键词 EAP pattern CIRCULATION SEASONAL forecast surface temperature eastern RUSSIA
在线阅读 下载PDF
Air transportation in China: Temporal and spatial evolution and development forecasts 被引量:7
16
作者 吴相利 满姗 《Journal of Geographical Sciences》 SCIE CSCD 2018年第10期1485-1499,共15页
This paper analyses the features and dynamic changes of the spatial layout of air transportation utilization among different provinces in China. It makes use of data for the airport throughput and socio-economic devel... This paper analyses the features and dynamic changes of the spatial layout of air transportation utilization among different provinces in China. It makes use of data for the airport throughput and socio-economic development of every province throughout the country in the years 2006 and 2015, and employs airport passenger and cargo throughput per capita and per unit of GDP as measures of regional air transportation utilization, which is significant for refining indicators of regional air transportation scale and comparing against them. It also analyzes the spatial differences of coupling between the regional air transportation utilization indicators and the key influencing factors on regional air transportation demand and utilization, which include per capita GDP, urbanization rate, and population density. Based on these key influencing factors, it establishes a multiple linear regression model to conduct forecasting of each province's future airport passenger and cargo throughput as well as throughput growth rates. The findings of the study are as follows:(1) Between 2006 and 2015, every province throughout the country showed a trend of year on year growth in their airport passenger and cargo throughput per capita. Throughput per capita grew fastest in Hebei, with a rise of 780%, and slowest in Beijing, with a rise of 38%. Throughput per capita was relatively high in western and southeastern coastal regions, and relatively low in northern and central regions. Airport passenger and cargo throughput per unit of GDP showed growth in provinces with relatively slow economic development, and showed negative growth in provinces with relatively rapid economic development. Throughput per unit of GDP grew fastest in Hebei, rising 265% between 2006 and 2015, and Hunan had the fastest negative growth, with a fall of 44% in the same period. Southwestern regions had relatively high throughput per unit of GDP, while in central, northern, and northeastern regions it was relatively low.(2) Strong correlation exists between airport passenger and cargo throughput per capita and per capita GDP, urbanization rate, and population density. Throughput per capita has positive correlation with per capita GDP and urbanization rate in all regions, and positive correlation with population density in most regions. Meanwhile, there is weak correlation between airport passenger and cargo throughput per unit of GDP and per capita GDP, urbanization rate, and population density, with positive correlation in some regions and negative correlation in others.(3) Between 2015 and 2025, it is estimated that all provinces experience a trend of rapid growth in their airport passenger and cargo throughput. Inner Mongolia and Hebei will see the fastest growth, rising221% and 155%, respectively, while Yunnan, Sichuan, and Hubei will see the slowest growth, with increases of 62%, 63%, and 65%, respectively. 展开更多
关键词 air transportation utilization temporal and spatial patterns influencing factors development forecasting China
原文传递
Forecasting regional economic growth using support vector machine model 被引量:1
17
作者 ZHANG Kun 《Ecological Economy》 2019年第3期186-192,共7页
Support vector machine(SVM)is a new technology in data mining.It is a new tool to solve machine learning problems with the help of optimization.Support vector machines belong to a new machine learning that extends fro... Support vector machine(SVM)is a new technology in data mining.It is a new tool to solve machine learning problems with the help of optimization.Support vector machines belong to a new machine learning that extends from statistical learning theory.Its structure is relatively simple,with good generalization ability and global optimality.Support vector machine has provided a unified framework for solving finite sample learning problems,and there are many solutions proposed.It can deal with those more complex problems and introduce the characteristics of the support vector machine model.Aiming at the application of the model in economic forecasting,a method to improve the prediction accuracy of the model is proposed.The theoretical analysis and practical application verification are performed,which shows that this method can obtain more accurate prediction results. 展开更多
关键词 support VECTOR MACHINE pattern RECOGNITION ECONOMIC growth forecast
原文传递
Case Study of Fog Predictability for an Event with Cold-Front Synoptic Pattern
18
作者 HU Huiqin HUANG Fei +3 位作者 ZHANG Shaoqing RUAN Chengqing GAO Shanhong LI Pengyuan 《Journal of Ocean University of China》 SCIE CAS CSCD 2019年第2期271-281,共11页
Fog has recently become a frequent high-impact weather phenomenon along the coastal regions of North China. Accurate fog forecasting remains challenging due to limited understanding of the predictability and mechanism... Fog has recently become a frequent high-impact weather phenomenon along the coastal regions of North China. Accurate fog forecasting remains challenging due to limited understanding of the predictability and mechanism of fog formation associated with synoptic-scale circulation. One frequent synoptic pattern of fog formation in this area is associated with cold front passage(cold-front synoptic pattern, CFSP). This paper explored the predictability of a typical CFSP fog event from the perspective of analyzing key characteristics of synoptic-scale circulation determining fog forecasting performance and the possible mechanism. The event was ensemble forecasted with the Weather Research and Forecasting model. Two groups of ensemble members with good and bad forecasting performance were selected and composited. Results showed that the predictability of this case was largely determined by the simulated strengths of the cold-front circulation(i.e., trough and ridge and the associated surface high). The bad-performing members tended to have a weaker ridge behind a stronger trough, and associated higher pressure over land and a weaker surface high over the sea, leading to an adverse impact on strength and direction of steering flows that inhibit warm moist advection and enhance cold dry advection transported to the focus region. Associated with this cold dry advection, adverse synoptic conditions of stratification and moisture for fog formation were produced, consequently causing failure of fog forecasting in the focus region. This study highlights the importance of accurate synoptic-scale information for improved CFSP fog forecasting, and enhances understanding of fog predictability from perspective of synoptic-scale circulation. 展开更多
关键词 FOG PREDICTABILITY cold-front SYNOPTIC pattern ensemble forecast composite analysis
在线阅读 下载PDF
基于需求模式自适应匹配的间歇性需求预测方法 被引量:1
19
作者 范黎林 曹富康 +2 位作者 王琬婷 杨凯 宋钊瑜 《计算机应用》 CSCD 北大核心 2024年第9期2747-2755,共9页
大型制造企业售后配件的需求分布稀疏、波动性大,需求频率和需求数量不确定性较高,序列呈现出典型的间歇性特点。在实际运维中,配件需求在频率和数量方面存在较大波动,从而产生变化多样的需求模式,而现有间歇性需求预测主要采用单一或... 大型制造企业售后配件的需求分布稀疏、波动性大,需求频率和需求数量不确定性较高,序列呈现出典型的间歇性特点。在实际运维中,配件需求在频率和数量方面存在较大波动,从而产生变化多样的需求模式,而现有间歇性需求预测主要采用单一或静态组合的固定预测模型,难以充分挖掘不同需求模式下需求序列的演化规律,预测精度和稳定性均难以保证。为解决上述问题,提出一种基于需求模式自适应匹配的间歇性需求预测方法,通过动态识别和匹配需求模式提升间歇性序列预测效果。该方法包括两个阶段:在模型训练阶段,首先,根据配件历史需求数据的间歇性特征,将它划分为需求量序列和间隔量序列,并对两类序列分别进行聚类,以捕获每类序列对应的不同需求和间隔模式;其次,建立包含统计学分析模型、浅层机器学习模型及深度学习模型的预测模型库,测试各模型对每种需求模式的预测效果,识别并标记每类需求模式的最优预测模型。在预测阶段,将待预测序列划分为需求量序列和间隔量序列,确定需求模式并匹配最佳预测模型,进而将需求量和间隔量的预测值合并,形成最终预测结果。在美国汽车公司和英国空军的间歇性配件需求数据集上的实验结果表明,所提方法可适用于不同需求模式的配件历史数据,通过自适应匹配需求模式和最优预测模型,有效提升了预测精度。 展开更多
关键词 间歇性序列 需求预测 时间序列预测 需求模式识别 配件管理
在线阅读 下载PDF
Factors That Affect Consumption Patterns and Market Demands for Honey in the Kingdom of Saudi Arabia
20
作者 Sobhy Ismaiel Safar Al Kahtani +2 位作者 Nuru Adgaba Ahmed A. Al-Ghamdi Abdu Zulail 《Food and Nutrition Sciences》 2014年第17期1725-1737,共13页
Despite the significant annual consumption of honey in Saudi Arabia, information gaps remain with regard to the marketing and market structure of honey along the value chain. This study analyzed the major factors that... Despite the significant annual consumption of honey in Saudi Arabia, information gaps remain with regard to the marketing and market structure of honey along the value chain. This study analyzed the major factors that influenced the consumption, expenditure patterns, and demand of honey in Saudi Arabia. This study forecasted the near-future expected market demands for honey in Saudi Arabia by collecting and analyzing the primary data using questionnaires. A total of 331 respondents from representative regions and large cities were randomly selected and interviewed. The data were analyzed using qualitative and quantitative methods as well as appropriate econometric models. Respondents characterized honey quality using organoleptic words, and these characterizations varied based on the relative significance of perception parameters. Taste, aroma, physical state, and color had aggregated average scores of 4.58, 4.44, 3.54, and 3.28, respectively. In addition to the above parameters, honey source, brand name, and confidence in the producers influenced its perceived quality. The major outlets for honey in Saudi Arabia included producers, specialized honey stores, and auction markets in major cities during the harvesting seasons. Medication, food, and sweetening were the major motivations for buying honey in the Saudi market, with aggregate scores of 4.52, 3.71, and 1.52, respectively. Significant honey price variations were observed within and among different honeys and packaging volumes;this finding might be due to factors such as botanical and geographical origins, package volume size economics (i.e., bulk purchases), honey variety blending, brand names, and producer policies. The average price of locally produced honey was approximately $73 per kg, which is 10 times more than the average price of honey in the US and the EU. The estimated consumption/income elasticity was 0.27. These results suggest that honey is a basic commodity in Saudi Arabia. Based on econometric model forecasts, the Saudi market demand for honey is expected to reach approximately 29,784 tons in 2025. 展开更多
关键词 HONEY Consumption patterns DEMAND forecasting HONEY Quality ELASTICITY MARKETING DEFICIENCIES
暂未订购
上一页 1 2 16 下一页 到第
使用帮助 返回顶部