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Database of molecular masers and variable stars
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作者 Andrej M.Sobolev Dmitry A. Ladeyschikov Jun-ichi Nakashima 《天文和天体物理学研究:英文版》 SCIE CAS CSCD 2019年第3期13-20,共8页
We present the database of maser sources in H2 O,OH and Si O lines that can be used to identify and study variable stars at evolved stages.Detecting the maser emission in H2 O,OH and Si O molecules toward infrared-exc... We present the database of maser sources in H2 O,OH and Si O lines that can be used to identify and study variable stars at evolved stages.Detecting the maser emission in H2 O,OH and Si O molecules toward infrared-excess objects is one of the methods for identifing long-period variables(LPVs,including miras and semiregulars),because these stars exhibit maser activity in their circumstellar shells.Our sample contains 1803 known LPV objects.Forty-six percent of these stars(832 objects)manifest maser emission in the line of at least one molecule:H2 O,OH or Si O.We use the database of circumstellar masers in order to search for LPVs which are not included in the General Catalogue of Variable Stars(GCVS).Our database contains 4806 objects(3866 objects without associations in GCVS)with maser detection in at least one molecule.Therefore it is possible to use the database in order to locate and study the large sample of LPV stars.The database can be accessed at http://maserdb.net. 展开更多
关键词 catalogs-astronomical DATABASES STARS VARIABLES general-stars masers-physical data and processes
Variability of emission lines in the optical spectra of the Herbig Be binary system HD 200775
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作者 Anastasia P.Bisyarina Andrey M.Sobolev +1 位作者 Stanislav Yu.Gorda Anatoly S.Miroshnichenko 《天文和天体物理学研究:英文版》 SCIE CAS CSCD 2019年第3期31-34,共4页
In our previous papers we have improved the value of the orbital period of the binary Herbig Be star HD 200775 and showed that the [O I] and Si II 6347 and 6371 ?A emission lines displayed variations which correlate w... In our previous papers we have improved the value of the orbital period of the binary Herbig Be star HD 200775 and showed that the [O I] and Si II 6347 and 6371 ?A emission lines displayed variations which correlate with the orbital period.In this paper we provide evidences that other broad emission lines of metals in the spectra of HD 200775 also exhibit variability,which is probably related to the orbital cycle of the binary.Analysis was performed based on the high-resolution spectral data collected over a time span of 6 years at the Kourovka Astronomical Observatory of the Ural Federal University(Russia)and the Three College Observatory of the University of North Carolina at Greensboro(USA)as well as archival spectral data compiled since 1994.We report new data points in the radial velocity curve of the He I 5876 ?A line near the extremal values of the radial velocity. 展开更多
关键词 techniques spectroscopic-stars variables T Tauri Herbig Ae/Be-stars individual HD 200775
A word about the teacher
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作者 Galina N.Dryomova Olga V.Eretnova Tatyana S.Polushina 《天文和天体物理学研究:英文版》 SCIE CAS CSCD 2019年第3期35-46,共12页
This is a memorial report on the biography and scientific heritage of M.A.Svechnikov-an outstanding scientist and teacher,the founder of the Ural school of close binary stars and the author of the classification schem... This is a memorial report on the biography and scientific heritage of M.A.Svechnikov-an outstanding scientist and teacher,the founder of the Ural school of close binary stars and the author of the classification scheme for eclipsing variable stars. 展开更多
关键词 catalogs photometric-spectroscopic-stars ECLIPSING variables classification scheme-close binary STARS
《诗经·国风》标题中的规律和变数探究 预览
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作者 刘砚秋 《淮海工学院学报:人文社会科学版》 2019年第5期38-41,共4页
在总体的观察下,《诗经》的篇目标题是存在着一些规律的。以《国风》为例,其大部分的标题都遵循着一定的规律,这些规律与先民的一些特点有紧密联系;出现的几个不符合规律的变数又把焦点聚集在《周南》,使其呈现出一种特殊性。
关键词 《诗经·国风》 标题 规律 变数
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国内外农用喷雾机的发展现状及趋势 预览
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作者 李震 孙宜田 +2 位作者 何青海 刘美丽 李曰阳 《农业装备与车辆工程》 2019年第3期23-26,共4页
分析了国内外农用喷雾机的发展现状,把当前我国农用喷雾机现状与国外相比较,客观地提出了国内外农用喷雾机未来的发展趋势。提出了精准变量施药技术、混药技术以及机电一体化技术的提升会促进喷雾机进一步的大发展。
关键词 农用喷雾机 变量 施药 混药 一体化
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Environmental factors influencing snowfall and snowfall prediction in the Tianshan Mountains, Northwest China
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作者 ZHANG Xueting LI Xuemei +2 位作者 LI Lanhai ZHANG Shan QIN Qirui 《干旱区科学:英文版》 SCIE CSCD 2019年第1期15-28,共14页
Snowfall is one of the dominant water resources in the mountainous regions and is closely related to the development of the local ecosystem and economy. Snowfall predication plays a critical role in understanding hydr... Snowfall is one of the dominant water resources in the mountainous regions and is closely related to the development of the local ecosystem and economy. Snowfall predication plays a critical role in understanding hydrological processes and forecasting natural disasters in the Tianshan Mountains, where meteorological stations are limited. Based on climatic, geographical and topographic variables at 27 meteorological stations during the cold season(October to April) from 1980 to 2015 in the Tianshan Mountains located in Xinjiang of Northwest China, we explored the potential influence of these variables on snowfall and predicted snowfall using two methods: multiple linear regression(MLR) model(a conventional measuring method) and random forest(RF) model(a non-parametric and non-linear machine learning algorithm). We identified the primary influencing factors of snowfall by ranking the importance of eight selected predictor variables based on the relative contribution of each variable in the two models. Model simulations were compared using different performance indices and the results showed that the RF model performed better than the MLR model, with a much higher R~2 value(R~2=0.74;R~2, coefficient of determination) and a lower bias error(RSR=0.51;RSR, the ratio of root mean square error to standard deviation of observed dataset). This indicates that the non-linear trend is more applicable for explaining the relationship between the selected predictor variables and snowfall. Relative humidity, temperature and longitude were identified as three of the most important variables influencing snowfall and snowfall prediction in both models, while elevation, aspect and latitude were of secondary importance, followed by slope and wind speed. These results will be beneficial to understand hydrological modeling and improve management and prediction of water resources in the Tianshan Mountains. 展开更多
关键词 SNOWFALL PREDICTION SNOWFALL fraction random forest multiple linear regression PREDICTOR variables TIANSHAN Mountains
Variable binaries and variables in binaries in the Binary star DataBase
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作者 Dana Kovaleva Oleg Malkov Pavel Kaygorodov 《天文和天体物理学研究:英文版》 SCIE CAS CSCD 2019年第3期7-12,共6页
The Binary star DataBase(BDB,http://bdb.inasan.ru)combines data from catalogs of binary and multiple stars of all observational types.There is a number of ways for variable stars to form or to be a part of binary or m... The Binary star DataBase(BDB,http://bdb.inasan.ru)combines data from catalogs of binary and multiple stars of all observational types.There is a number of ways for variable stars to form or to be a part of binary or multiple systems.We describe how such stars are represented in the database. 展开更多
关键词 astronomical data bases-stars BINARIES general-stars VARIABLES GENERAL
Sharp L^p decay of oscillatory integral operators with certain homogeneous polynomial phases in several variables
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作者 Shaozhen Xu Dunyan Yan 《中国科学:数学英文版》 SCIE CSCD 2019年第4期649-662,共14页
In this paper, we obtain the L^p decay of oscillatory integral operators Tλ with certain homogeneous polynomial phase functions of degree d in(n + n)-dimensions;we require that d > 2 n. If d/(d-n)< p < d/n,t... In this paper, we obtain the L^p decay of oscillatory integral operators Tλ with certain homogeneous polynomial phase functions of degree d in(n + n)-dimensions;we require that d > 2 n. If d/(d-n)< p < d/n,the decay is sharp and the decay rate is related to the Newton distance. For p = d/n or d/(d-n), we obtain the almost sharp decay, where "almost" means that the decay contains a log(λ) term. For otherwise, the L^p decay of Tλ is also obtained but not sharp. Finally, we provide a counterexample to show that d/(d-n) p d/n is not necessary to guarantee the sharp decay. 展开更多
关键词 OSCILLATORY integral operators SHARP L^p DECAY several VARIABLES Newton distance
The environmental implication of diatom fossils in the surface sediment of the Changjiang River estuary (CRE) and its adjacent area 预览
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作者 FAN Xin CHENG Fangjin +1 位作者 YU Zhiming SONG Xiuxian 《海洋湖沼学报(英文)》 SCIE CAS CSCD 2019年第2期552-567,共16页
In order to depict the distribution of diatom fossils in surface sediments and to establish a reliable reference data for further paleoenvironmental study in the Changjiang (Yangtze) River estuary and its adjacent wat... In order to depict the distribution of diatom fossils in surface sediments and to establish a reliable reference data for further paleoenvironmental study in the Changjiang (Yangtze) River estuary and its adjacent waters, the diatom fossils from 34 surface sediment samples and their relationship with environmental variables were analyzed by principal component analysis and redundancy correspondence analysis. The diversity and abundance of diatom fossils were analyzed. Some annual average parameters of the overlying water (salinity, temperature, turbidity, dissolved oxygen, depth, dissolved inorganic nitrogen, dissolved inorganic phosphate and dissolved inorganic silicate) were measured at each sampling site. A total of 113 diatom taxa and one silicoflagellate species were identified in the investigation area. Diatom fossils were better preserved in fine sediments. The absolute abundance of diatom fossils did not significantly diff er between inshore and off shore areas, the species diversity decreased from inshore to off shore. This may be because high nutrients and low salinity promoted the growth of more brackish species in coastal waters. The diatom taxa were divided into three groups, on the basis of their response and indication to environmental changes. For example, Actinocyclus ehrenbergii and Cyclotella stylorum were dominant in coastal waters (Group 1 and Group 3) with high nutrients and low salinity;the relative abundances of Paralia sulcata and Podosira stelliger were significantly higher in off shore sites (Group 2, average 39.5%), which were characterized by high salinity and deep water. Four environmental variables (salinity, dissolved inorganic nitrogen, temperature and water depth) explained the composition and distribution of diatom taxa independently ( P< 0.05), this finding can be applied in further paleoenvironmental reconstruction research in this area. 展开更多
关键词 DIATOM FOSSILS CHANGJIANG River ESTUARY surface sediments environmental VARIABLES
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More than two hundred and fifty thousand spectroscopic binary or variable star candidates discovered by LAMOST
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作者 Sheng-Bang Qian Xiang-Dong Shi +7 位作者 Li-Ying Zhu Lin-Jia Li Jia Zhang Er-Gang Zhao Zhong-Tao Han Xiao Zhou Xiao-Hui Fang Wen-Ping Liao 《天文和天体物理学研究:英文版》 SCIE CAS CSCD 2019年第5期15-26,共12页
About 786.4 thousand stars were observed by LAMOST twice or more during the first stage of its spectroscopic survey. The radial velocity differences for about 256 thousand targets are larger than10 km s-1 and they are... About 786.4 thousand stars were observed by LAMOST twice or more during the first stage of its spectroscopic survey. The radial velocity differences for about 256 thousand targets are larger than10 km s-1 and they are possible spectroscopic binary or variable candidates(SBVCs). It is shown that most SBVCs are slightly metal poorer than the Sun. There are two peaks in the temperature distribution of SBVCs around 5760 K and 4870 K, while there are three peaks in the distribution of the gravitational acceleration at 2.461, 4.171 and 4.621 cm s^-2. The locations of SBVCs on the [Fe/H]-T,[Fe/H]-log g, log g-T and H-R diagrams are investigated. It is found that the detected SBVCs could be classified into four groups. The first group has higher log g~4.621 and lower T ~ 4870 K which are mainly cool red dwarf binaries. The second group of SBVCs has logg around 4.171 cm s^-2 that includes binaries and pulsating stars such as δSet and γ Dor variables. The gravitational accelerations of the third group of SBVCs are higher and some of them are below the zero-age main sequence. They may be contact binaries in which the primary components are losing energy to the secondaries in the common envelopes and are at a special stellar evolutionary stage.The last group is composed of giants or supergiants with log g around 2.461 cm s^-2 that may be evolved pulsating stars. One target(C134624.29+333921.2) is confirmed as an eclipsing binary with a period of 0.65 days. A preliminary analysis suggests that it is a detached binary with a mass ratio of 0.46. The primary fills its critical Roche lobe by about 89%, indicating that mass transfer will occur between the two components. 展开更多
关键词 STARS fundamental parameters-stars BINARIES spectroscopic-stars:oscillations-stars:binaries eclipsing-stars variables other
Shareholder Structure and Discretionary Regulation of Accounting Results in Enterprises: The Case of Cameroon 预览
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作者 Kadouamai Souleymanou Zakarine Talaka 《现代会计与审计:英文版》 2019年第1期1-27,共27页
Debates on shareholder structure and discretionary management of accounting results have carried forward controversial results. This study is intended to analyze within the Cameroonian context the impact of shareholde... Debates on shareholder structure and discretionary management of accounting results have carried forward controversial results. This study is intended to analyze within the Cameroonian context the impact of shareholder structure on the management of accounting results in enterprises. More specifically, its objective is to analyze the impact of shareholder structure on the adjustment of regulating discretionary accounting variables. A panel of enterprises is constituted over the periods 2013, 2014, and 2015 in Cameroon. The modeling of regulating discretionary accounting variables has been carried out according to the model of Jones (1991). The different results obtained show that the degree of concentration of the capital seems not to dissuade the management of result per long-term positions. Foreign ownership and state property stimulate management by regulating discretionary accounting variables. 展开更多
关键词 SHAREHOLDER structure management of RESULTS ACCOUNTING VARIABLES discretional REGULATIONS control systems
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Variable-top stem biomass equations at tree-level generated by a simultaneous density-integral system for second growth forests of roble, raulí, and coigüe in Chile 预览
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作者 Carlos Valenzuela Eduardo Acuna +3 位作者 Alicia Ortega Geronimo Quinonez-Barraza Jose Corral-Rivas Jorge Cancino 《林业研究:英文版》 CAS CSCD 2019年第3期993-1010,共18页
Variable-top stem biomass models at the tree level for second growth forests of roble (Nothofagus obliqua), rauli(Nothofagus alpina), and coigüe (Nothofagus dombeyi) were fitted by a simultaneous density-integral... Variable-top stem biomass models at the tree level for second growth forests of roble (Nothofagus obliqua), rauli(Nothofagus alpina), and coigüe (Nothofagus dombeyi) were fitted by a simultaneous density-integral system, which combines a stem taper model and a wood basic density model. For each model, an autoregressive structure of order 2 and a power equation of residual variance were incorporated to reduce residual autocorrelation and heteroscedasticity, respectively. By using dummy variables in the regression analysis, zonal effects on the parameters in the variable-top stem biomass equations were detected in roble. Consequently, equations for clusters of zones were obtained. These equations presented significant parameters and a high precision in both fitting and validation processes (i.e., CV<11.5% and CVp<11.9%, respectively), demonstrating that they are unbiased. The advantage of these types of functions is that they provide estimates of volume and biomass of sections of the stem, defined between any two points of the stem in the three species. Thus, depending on the final use of the wood and the dimensions of the tree, a stem fraction can be quantified in units of volume and the remaining fraction in units of weight. 展开更多
关键词 AUTOCORRELATION Density-integral DUMMY variables AUTOREGRESSIVE error structure HETEROSCEDASTICITY
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A Note on the Transformation of Variables of KP Equation, Cylindrical KP Equation and Spherical KP Equation
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作者 刘春平 《理论物理通讯:英文版》 SCIE CAS CSCD 2019年第2期170-174,共5页
In a recent article(Commun. Theor. Phys. 67(2017) 207), three(2+1)-dimensional equations — KP equation, cylindrical KP equation and spherical KP equation, have been reduced to the same Kd V equation by using differen... In a recent article(Commun. Theor. Phys. 67(2017) 207), three(2+1)-dimensional equations — KP equation, cylindrical KP equation and spherical KP equation, have been reduced to the same Kd V equation by using different transformation of variables, respectively. In this short note, by adding an adjustment item to original transformation, three more general transformation of variables corresponding to above three equations have been given.Substituting the solutions of the Kd V equation into our transformation of variables, more new exact solutions of the three(2+1)-dimensional equations can be obtained. 展开更多
关键词 transformation of VARIABLES KP EQUATION CYLINDRICAL KP EQUATION SPHERICAL KP EQUATION
Rock fracture density characterization using measurement while drilling(MWD)techniques 预览
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作者 Mohammad Babaei Khorzoughi Robert Hall Derek Apel 《矿业科学技术学报:英文版》 CSCD 2018年第6期859-864,共6页
Accurate determination of rock mass properties is a critical part of open-pit mine planning activities to enable more prescriptive blast designs to achieve improved loading and hauling and downstream process efficienc... Accurate determination of rock mass properties is a critical part of open-pit mine planning activities to enable more prescriptive blast designs to achieve improved loading and hauling and downstream process efficiency.Better and more accurate blast practice that delivers enhanced outcomes(better fragmentation,improved diggability,less dilution,etc.)is a critical and fundamental element of being able to achieve an effective Mine-Mill approach at a mining operation.Based on previous work,it has been demonstrated that an accurate representation of the rock mass properties can be obtained from the analysis of variations in blasthole drill performance as derived from measurement while drilling(MWD)systems when using tricone bits.This paper further investigates how monitored rate of penetration,pulldown force,rotary torque,rotary speed and bailing air pressure responses can be used to determine the presence of open and partially open fractures having varying dip angles.Based on a correlation of geophysically measured fracture logs and monitored drill performance variables in the same blastholes,the results show that the latter responses can accurately determine open versus closed fractures.The results also identified that variations in rate of penetration and rotary torque show the most sensitivity in the presence of open fractures that intersect a vertical blasthole at near orthogonal angles. 展开更多
关键词 Measurement WHILE drilling FRACTURES Rotary blasthole DRILL DRILL performance VARIABLES Fracture frequency LOGGING
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The Fifth Edition of the General Catalogue of Variable Stars: experiences in the constellation Centaurus
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作者 Nikolay N. Samus Elena N. Pastukhova +1 位作者 Olga V. Durlevich Elena V. Kazarovets 《天文和天体物理学研究:英文版》 SCIE CAS CSCD 2018年第7期93-100,共8页
关键词 可变性 人马座 星座 版本 目录 天体物理学 多周期 轻元素
On the strong convergence properties for weighted sums of negatively orthant dependent random variables 预览
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作者 DENG Xin TANG Xu-fei +1 位作者 WANG Shi-jie WANG Xue-jun 《高校应用数学学报:英文版(B辑)》 SCIE CSCD 2018年第1期35-47,共13页
In the paper, the strong convergence properties for two different weighted sums of negatively orthant dependent (NOD) random variables are investigated. Let {Xn, n ≥ 1} be a sequence of NOD random variables. The resu... In the paper, the strong convergence properties for two different weighted sums of negatively orthant dependent (NOD) random variables are investigated. Let {Xn, n ≥ 1} be a sequence of NOD random variables. The results obtained in the paper generalize the corresponding ones for i.i.d. random variables and identically distributed NA random variables to the case of NOD random variables, which are stochastically dominated by a random variableX. As a byproduct, the Marcinkiewicz-Zygmund type strong law of large numbers for NOD random variables is also obtained. 展开更多
关键词 STRONG CONVERGENCE negatively orthant dependent random VARIABLES STOCHASTIC DOMINATION
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Epidemiological 被引量:10
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作者 Alberto Caballero Vázquez Ana Dolores Romero Ortiz +2 位作者 Jose Manuel González de Vega San Román Raimundo García del Moral Bernardino Alcázar Navarrete 《中国肺癌杂志》 CSCD 北大核心 2018年第1期32-36,共5页
Background: Changes in lung cancer has been characterized by the increase of cases among women and the increase in adenocarcinomas among other histological subtypes.Methods: Descriptive analysis of cases diagnosed w... Background: Changes in lung cancer has been characterized by the increase of cases among women and the increase in adenocarcinomas among other histological subtypes.Methods: Descriptive analysis of cases diagnosed with lung cancer in Hospital Virgen de las Nieves(Spain) from 1990 to 2010,based on five variables(age, sex, smoking, histology and pathological anatomy). The study establishes associations between these variables and compares the results with the literature.Results: 2,026 patients were diagnosed with lung cancer in this period; 1,838 were males(90.7%) and 188 women(9.3%); 1,892 patients(93.4%) were smokers or ex-smokers and 134(6.6%) had never smoked; the most frequent non-small cell histology types were squamous cell carcinoma and adenocarcinoma and it was the most frequent neoplasia in women and were associated with a lower tobacco consumption.Conclusion: The large majority of lung cancer cases is associated with a history of smoking tobacco and there are histopathological differences according to gender and cumulative tobacco smoke load. 展开更多
关键词 EVOLUTION
基于多语体语料库的典型make类迂回致使结构研究 被引量:1
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作者 杨江锋 《西安外国语大学学报》 CSSCI 2018年第3期51-57,共7页
本研究以英国国家语料库中口语对话、小说、新闻报刊和学术刊物四种语料为基础,调查典型make类迂回致使结构及该结构中致使者、被使者和结果动词三个主要槽位的填充词在语义、语法属性特征上所表现出来的语体偏向效应。统计表明,从四种... 本研究以英国国家语料库中口语对话、小说、新闻报刊和学术刊物四种语料为基础,调查典型make类迂回致使结构及该结构中致使者、被使者和结果动词三个主要槽位的填充词在语义、语法属性特征上所表现出来的语体偏向效应。统计表明,从四种语体上看,典型make类迂回致使结构显著多用于小说语体中;从口笔语两大语域上看,多用于书面语中。致使者和被使者各自的生命度特征、具体语义特征以及所表达的致使类型在四类不同语体中表现出明显的语体偏向;不同语体对不同语法类型和意义类型的结果动词有着明显选择偏向。不同语体对同一语言结构原型意义的构建有重要的影响。 展开更多
关键词 迂回致使结构 MAKE 语料库 语体分析 因素
Day-ahead industrial load forecasting for electric RTG cranes 预览
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作者 Feras ALASALI Stephen HABEN +1 位作者 Victor BECERRA William HOLDERBAUM 《现代电力系统与清洁能源学报(英文)》 2018年第2期223-234,共12页
Given the increase in international trading and the significant energy and environmental challenges in ports around the world, there is a need for a greater understanding of the energy demand behaviour at ports.The mo... Given the increase in international trading and the significant energy and environmental challenges in ports around the world, there is a need for a greater understanding of the energy demand behaviour at ports.The move towards electrified rubber-tyred gantry(RTG)cranes is expected to reduce gas emissions and increase energy savings compared to diesel RTG cranes but it will increase electrical energy demand. Electrical load forecasting is a key tool for understanding the energy demand which is usually applied to data with strong regularities and seasonal patterns. However, the highly volatile and stochastic behaviour of the RTG crane demand creates a substantial prediction challenge. This paper is one of the first extensive investigations into short term load forecastsfor electrified RTG crane demand. Options for model inputs are investigated depending on extensive data and correlation analysis. The effect of estimation accuracy of exogenous variables on the forecast accuracy is investigated as well. The models are tested on two different RTG crane data sets that were collected from the Port of Felixstowe in the UK. The results reveal the effectiveness of the forecast models when the estimation of the number of crane moves and container gross weight are accurate. 展开更多
关键词 Rubber-tyred gantry(RTG) cranes Correlation analysis EXOGENOUS VARIABLES estimation Artificial neural networks Time series forecast modelling
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数学模型用以提高印制电路板电镀参数准确性的研究 预览
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作者 翟青霞 彭卫红 许娟娟 《印制电路信息》 2018年第A02期323-329,共7页
文章通过匹配Tobin模型等计量模型与最优控制模型.计算不同铜厚要求的印制电路板的电流密度和电镀时间最优水平,进而建立各批印制电路板订单的电流密度和电镀时间的数学模型。并将该模型嵌入公司ERP系统。以提高电镀工作效率。同时达... 文章通过匹配Tobin模型等计量模型与最优控制模型.计算不同铜厚要求的印制电路板的电流密度和电镀时间最优水平,进而建立各批印制电路板订单的电流密度和电镀时间的数学模型。并将该模型嵌入公司ERP系统。以提高电镀工作效率。同时达到降低生产成本的目的。 展开更多
关键词 数学模型 变量 电镀参数 最优的
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