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Combined hybrid energy storage system and transmission grid model for peak shaving based on time series operation simulation 被引量:1
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作者 Mingkui Wei Yiyu Wen +3 位作者 Qiu Meng Shunwei Zheng Yuyang Luo Kai Liao 《Global Energy Interconnection》 EI CAS CSCD 2023年第2期154-165,共12页
This study proposes a combined hybrid energy storage system(HESS) and transmission grid(TG) model, and a corresponding time series operation simulation(TSOS) model is established to relieve the peak-shaving pressure o... This study proposes a combined hybrid energy storage system(HESS) and transmission grid(TG) model, and a corresponding time series operation simulation(TSOS) model is established to relieve the peak-shaving pressure of power systems under the integration of renewable energy. First, a linear model for the optimal operation of the HESS is established, which considers the different power-efficiency characteristics of the pumped storage system, electrochemical storage system, and a new type of liquid compressed air energy storage. Second, a TSOS simulation model for peak shaving is built to maximize the power entering the grid from the wind farms and HESS. Based on the proposed model, this study considers the transmission capacity of a TG. By adding the power-flow constraints of the TG, a TSOS-based HESS and TG combination model for peak shaving is established. Finally, the improved IEEE-39 and IEEE-118 bus systems were considered as examples to verify the effectiveness and feasibility of the proposed model. 展开更多
关键词 Peak shaving Hybrid energy storage system combined energy storage and transmission grid model Time series operation simulation
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Evaluation of the Application Effect of Short Video Combined with BOPPPS Teaching Mode in Clinical Anesthesia Teaching
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作者 Hong Xi Hua Bai +3 位作者 Xianhong Jiang Haiyan Huo Huihui Liu Nan Liu 《Journal of Contemporary Educational Research》 2023年第12期1-7,共7页
Objective:To study the application effect of short video combined with BOPPPS teaching mode in clinical anesthesia practice.Method:48 students assigned to clinical anesthesia in digestive endoscopy of Shanxi Bethune H... Objective:To study the application effect of short video combined with BOPPPS teaching mode in clinical anesthesia practice.Method:48 students assigned to clinical anesthesia in digestive endoscopy of Shanxi Bethune Hospital from July 1,2022 to April 1,2023 were selected as research objects.They were randomly divided into the control group(PowerPoint presentation teaching group)and the observation group(short video combined with BOPPPS teaching group),with 24 students in each group.After the internship,the students’theoretical and technical scores were tested,the effects of the two teaching modes were compared,and the students’satisfaction was investigated.Results:The test scores of students in the observation group were significantly better than those in the control group(P<0.05).The short video combined with BOPPPS teaching mode can significantly improve students’learning interest,operation skills,and memory(P<0.05).The students’satisfaction in the observation group was higher than that in the control group(P<0.05).Conclusion:In clinical practice,the application of short video combined with BOPPPS teaching mode has achieved great effect,which is worth further promotion and research. 展开更多
关键词 Short video combined with BOPPPS teaching model Clinical teaching of anesthesia Teaching effect Teaching evaluation
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Combined model of trip mode and destination 被引量:1
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作者 姜雨 陆键 《Journal of Southeast University(English Edition)》 EI CAS 2010年第4期633-637,共5页
This paper analyzes the characteristics of the destination distribution of trips and proposes a stratified sampling strategy for travel mode choice.The stratified sampling strategy can reduce the size of the alternati... This paper analyzes the characteristics of the destination distribution of trips and proposes a stratified sampling strategy for travel mode choice.The stratified sampling strategy can reduce the size of the alternative set;thus,the computation burden of simulation is decreased.Using the stratified sampling strategy,a combined choice model of the trip mode and destination is developed based on the Bayesian theory.Simulations are carried out to verify the proposed model.The results show that the combined choice model of the trip mode and destination can efficiently simulate travelers' choice behaviors.Furthermore,the forecasting accuracy of the combined choice model is higher than the one of the gravity model.Therefore,the proposed model is a powerful tool with which to analyze travelers' behaviors in selecting the trip mode. 展开更多
关键词 combined choice model discrete choice trip mode and destination sampling
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Combined model based on optimized multi-variable grey model and multiple linear regression 被引量:11
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作者 Pingping Xiong Yaoguo Dang +1 位作者 Xianghua wu Xuemei Li 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2011年第4期615-620,共6页
The construction method of background value is improved in the original multi-variable grey model (MGM(1,m)) from its source of construction errors. The MGM(1,m) with optimized background value is used to elimin... The construction method of background value is improved in the original multi-variable grey model (MGM(1,m)) from its source of construction errors. The MGM(1,m) with optimized background value is used to eliminate the random fluctuations or errors of the observational data of all variables, and the combined prediction model together with the multiple linear regression is established in order to improve the simulation and prediction accuracy of the combined model. Finally, a combined model of the MGM(1,2) with optimized background value and the binary linear regression is constructed by an example. The results show that the model has good effects for simulation and prediction. 展开更多
关键词 multi-variable grey model (MGM(1 m)) backgroundvalue OPTIMIZATION multiple linear regression combined predic-tion model.
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Combined Prediction for Vehicle Speed with Fixed Route 被引量:3
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作者 Lipeng Zhang Wei Liu Bingnan Qi 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2020年第4期113-125,共13页
Achieving accurate speed prediction provides the most critical support parameter for high-level energy management of plug-in hybrid electric vehicles.Nowadays,people often drive a vehicle on fixed routes in their dail... Achieving accurate speed prediction provides the most critical support parameter for high-level energy management of plug-in hybrid electric vehicles.Nowadays,people often drive a vehicle on fixed routes in their daily travels and accurate speed predictions of these routes are possible with random prediction and machine learning,but the prediction accuracy still needs to be improved.The prediction accuracy of traditional prediction algorithms is difficult to further improve after reaching a certain accuracy;problems,such as over fitting,occur in the process of improving prediction accuracy.The combined prediction model proposed in this paper can abandon the transitional dependence on a single prediction.By combining the two prediction algorithms,the fusion of prediction performance is achieved,the limit of the single prediction performance is crossed,and the goal of improving vehicle speed prediction performance is achieved.In this paper,an extraction method suitable for fixed route vehicle speed is designed.The application of Markov and back propagation(BP)neural network in predictions is introduced.Three new combined prediction methods,all named Markov and BP Neural Network(MBNN)combined prediction algorithm,are proposed,which make full use of the advantages of Markov and BP neural network algorithms.Finally,the comparison among the prediction methods has been carried out.The results show that the three MBNN models have improved by about 19%,28%,and 29%compared with the Markov prediction model,which has better performance in the single prediction models.Overall,the MBNN combined prediction models can improve the prediction accuracy by 25.3%on average,which provides important support for the possible optimization of plug-in hybrid electric vehicle energy consumption. 展开更多
关键词 Plug-in hybrid electric vehicles Energy consumption Vehicle speed prediction MARKOV BP neural networks combined prediction model
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A combined numerical tidal model for the Hangzhou Bay and Qiantang River 被引量:5
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作者 Cao Deming and Fang Guohong Institute of Oceanology, Academia Sinica, Qingdao, China 《Acta Oceanologica Sinica》 SCIE CAS CSCD 1989年第4期485-496,共12页
-In order to avoid prescribing open boundary condition on the upstream side of the Hangzhou Bay, in numerical simulation of the tides and residual currents of the Bay, a 1-D model for the Qiantang River is connected t... -In order to avoid prescribing open boundary condition on the upstream side of the Hangzhou Bay, in numerical simulation of the tides and residual currents of the Bay, a 1-D model for the Qiantang River is connected to the 2-D model for the Hangzhou Bay. The harmonic constants of diurnal constituent [ (K1+O1)/2],semidiurnal constituent (M2) and shallow water constituent (M4) are obtained. The results produced by the combined model are in better agreement with the observed ones than those produced solely by the original 2-D model. The combined model gives much more reliable results for tide-induced residual water level and current. 展开更多
关键词 A combined numerical tidal model for the Hangzhou Bay and Qiantang River BAY
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Study of establishing disease-syndrome combined with animal model for immune thrombocytopenic purpura without additional conditions 被引量:2
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作者 Haiyan Lang Ming Guo +4 位作者 Yuting Chu Wei Ma Yayue Zhang Ling Zhang Xinyi Chen 《Journal of Traditional Chinese Medical Sciences》 2016年第3期135-140,共6页
Objective:To explore the feasibility of establishing the disease-syndrome combined animal model for immune thrombocytopenic purpura(ITP)without additional conditions.Methods:Three batches of data related to the ITP mo... Objective:To explore the feasibility of establishing the disease-syndrome combined animal model for immune thrombocytopenic purpura(ITP)without additional conditions.Methods:Three batches of data related to the ITP model mice obtained by replication at different time were analyzed,and whether the APS-injected model mice replicated through the passive immune modeling method could simulate the pathogenesis and clinical characteristics of human ITP was evaluated according to the differentiation criteria for diseasesyndrome combined model.Results:The APS-injected replicated ITP model mice possessed the following traits:(1)Compared with the normal group,the platelet count was significantly decreased,and coagulation time was significantly increased in the model group(P<.01).(2)Compared with the normal group,the medullary thrombocytogenous megakaryocytes were significantly decreased(P<.05,.01,.001).(3)The APS-injected sites and other parts of the model mice had spontaneous hemorrhage.(4)Behavioral changing signs were observed 1 week after the modeling(i.e.low activity,delayed activity,poor appetite,skin petechia/hemorrhage and spontaneous hemorrhage at the injected sites or other parts),and were getting more and more severe.Conclusion:According to the syndrome differentiation criteria for disease-syndrome combined model of ITP,the APS-injected animal model of ITP replicated through the passive immune modeling method without additional conditions possesses the characteristics of disease-syndrome combined model.It provides an ideal tool for the development of traditional Chinese medicine pharmacology experiment. 展开更多
关键词 Immune thrombocytopenic purpura Syndrome of failure of spleen qi to control blood due to deficiency of spleen qi Disease-syndrome combined animal model
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A COMBINED MODEL OF WIND, WAVE, TIDE AND STORM SURGES
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作者 谢强 侯一筠 +2 位作者 尹宝树 范顺庭 程明华 《Chinese Journal of Oceanology and Limnology》 SCIE CAS CSCD 2000年第4期297-300,共4页
A combined numerical model of wind, wave, tide, and storm surges was built on the basis of the “wind field model in limited sea surface areas”. When used to forecast the sea surface wind, wave height and water level... A combined numerical model of wind, wave, tide, and storm surges was built on the basis of the “wind field model in limited sea surface areas”. When used to forecast the sea surface wind, wave height and water level, it can describe them very well. 展开更多
关键词 combined numerical model wind-wave-tide-storm surges FORECAST
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ARMA-GM combined forewarning model for the quality control
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作者 WangXingyuan YangXu 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2005年第1期224-227,共4页
Three forecasting models are set up: the auto\|regressive moving average model, the grey forecasting model for the rate of qualified products P t, and the grey forecasting model for time intervals of the quality cata... Three forecasting models are set up: the auto\|regressive moving average model, the grey forecasting model for the rate of qualified products P t, and the grey forecasting model for time intervals of the quality catastrophes. Then a combined forewarning system for the quality of products is established, which contains three models, judgment rules and forewarning state illustration. Finally with an example of the practical production, this modeling system is proved fairly effective. 展开更多
关键词 auto-regressive moving average model (ARMA) grey system model (GM) combined forewarning model quality control.
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Effects of ginsenoside of stem and leaf combined with choline on learning and memory ability of rat models with Alzheimer diseases 被引量:1
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作者 Xiaomin Zhao Xianglin Xie +3 位作者 Zuoli Xia Yunsheng Gao Yuyun Zhu Hongxia Gu 《Neural Regeneration Research》 SCIE CAS CSCD 2006年第4期331-334,共4页
BACKGROUND: Central adrenergic nerve and 5-serotonergic nerve can influence central cholinergic nerve on learning and memory and make easy for study; however, ginsenoside of stem and leaf (GSL) can improve function... BACKGROUND: Central adrenergic nerve and 5-serotonergic nerve can influence central cholinergic nerve on learning and memory and make easy for study; however, ginsenoside of stem and leaf (GSL) can improve functions of central adrenergic nerve; moreover, 5-serotonergic nerve and the combination with choline can produce synergistic effect and enhance learning and memory ability so as to improve learning and memory disorder of patients with Alzheimer disease (AD). OBJECTIVE : To observe the effects of GSL combining with choline on learning and memory of AD model rats DESIGN : Randomized grouping design and controlled animal study SETIING : Department of Pharmacology, Taishan Medical College MATERIALS : The experiment was carried out in the Pharmacological Department of Medical College of Jilin University from October 1996 to January 1997. Forty healthy male Wistar rats of clean grade were randomly divided into 5 groups, including sham-injury group, model group, GSL group, choline group and combination group, with 8 rats in each group. Main medications: GSL with the volume more than 92.8% was provided by Department of Chemistry, Norman Bethune Medical College of Jilin University. Panaxatriol, the main component, was detected with thin layer scanning technique and regarded as the index of GSL quality [(55±1)%, CV= 2%, n = 5]. Choline was provided by the Third Shanghai Laboratory Factory. METHODS : 150 nmol quinolinic acid was used to damage bilateral Meynert basal nuclei of adult rats so as to establish AD models. Rats in GSL, choline and combination groups were intragastric administrated with 400 mg/kg GSL, 200 mg/kg choline (20 mL/kg), and both respectively last for 17 days starting from two days before operation. Rats in sham-injury group and model group were perfused with the same volume of distilled water once in each morning for the same days. (1) Passive avoidance step-down test: Five minutes later, rats jumped up safe platform when they were shocked with 36 V alternating current. If rats jumped down from the platform and the feet touched railings, the response was wrong. Numbers of wrong response were recorded within 3 minutes, and then the test was redone after 24 hours. (2) Morris water-maze spatial localization task: Swimming from jumping-off to platform directly was regarded as right response. Additionally, 4 successively right responses were regarded as the standard. Each rat was trained 10 times a day with 120 s per time for 3 successive days. The interval was 30 s. Three days later, numbers of right response were recorded. The training times were increased to 30 for unlearned rats. (3) Measurement of activity of choline acetylase in cerebral cortex: Rats were sacrificed at 17 days after operation to obtain cerebral cortex to measure activity of choline acetylase with radiochemistry technique. (4) Synergistic effect: It was expressed as Q value: Q value = factual incorporative effect/anticipant incorporative effect; Q ≥ 1 was regarded as synergistic effect. Anticipant incorporative effect = (EA+EB-EA·EB), EA and EB were single timing effect, respectively in GSL group and choline group. E(step-down test and Morris water maze test) = (x in model group - factual value in medicine groups)/x in model group; E (activity of choline acetylase) = (factual value in medicine groups -xin model group)/xin model group. MAIN OUTCOME MEASURES : (1) Passive avoidance step-down test and Morris water-maze spatial localization task in the study of learning and memory; (2) activity of choline acetylase. RESULTS : All 40 rats were involved in the final analysis. (1) Passive avoidance response: At learning phase on first day and retesting phase on the next day, numbers of wrong responses within 3 minutes were more in model group than sham operation group, and there was significant difference [(5.88±1.46), (2.25±0.87) times; (2.63±1.06), (0.50±0.53) times; P 〈 0.01]; numbers of wrong responses within 3 minutes were less in combination group than model group, and there was significant difference [learning phase: (1.12±0.83), (5.88±1.46) times; retesting phase: (0.38±0.74), (2.63±1.06)times, P 〈 0.01]; moreover, effect was stronger than that in GSL group and choline group. The Q value was 1.07 and 1.59, respectively and it showed synergistic effect. Spatial localization task: Training times were more in model group than sham operation group, and there was significant difference [(2.9±2.5), (12.6±3.5) times; P 〈 0.01]. Training times were less in combination group than model group, and there was significant difference [(11.8±2.4), (27.9±2.5) times, P 〈 0.01]; moreover, effect was stronger than that in GSL group and choline group. The Q value was 1.07 and it showed synergistic effect. (3) Activity of choline acetylase: Activity was lower in model group than sham operation group, and there was significant difference [(30.56±8.33), (61.11 ±8.33) nkat/g; P 〈 0.01]. Activity was higher in combination group than model group and there was significant difference [(50.00±8.33), (30.56±8.33) nkat/g, P 〈 0.01];moreover, effect was stronger than that in GSL group and choline group. The Q value was 1.5 and it showed synergistic effect. CONCLUSZON: GSL in combination with choline can synergically improve the disorder of learning and memory of AD model rats. Its mechanism may be involved in enhancing the function of central cholinergic system. 展开更多
关键词 stem Effects of ginsenoside of stem and leaf combined with choline on learning and memory ability of rat models with Alzheimer diseases
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Combined bottleneck effect of on-ramp and bus stop in a cellular automaton model
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作者 宋玉鲲 赵小梅 《Chinese Physics B》 SCIE EI CAS CSCD 2009年第12期5242-5248,共7页
The combined bottleneck effect is investigated by modeling traffic systems with an on-ramp and a nearby bus stop in a two-lane cellular automaton model. Two cases, i.e. the bus stop locates in the downstream section o... The combined bottleneck effect is investigated by modeling traffic systems with an on-ramp and a nearby bus stop in a two-lane cellular automaton model. Two cases, i.e. the bus stop locates in the downstream section of the on-ramp and the bus stop locates in the upstream section of the on-ramp, are considered separately. The upstream flux and downstream flux of the main road, as well as the on-ramp flux are analysed in detail, with respect to the entering probabilities and the distance between the on-ramp and the bus stop. It is found that the combination of the two bottlenecks causes the capacity to drop off, because the vehicles entering the main road from the on-ramp would interweave with the stopping (pulling-out) buses in the downstream (upstream) case. The traffic conflict in the former case is much heavier than that in the latter, causing the downstream main road to be utilized inefficiently. This suggests that the bus stop should be set in the upstream section of the on-ramp to enhance the capacity. The fluxes both on the main road and on the on-ramp vary with the distance between the two bottlenecks in both cases. However, the effects of distance disappear gradually at large distances. These findings might give some guidance to traffic optimization and management. 展开更多
关键词 cellular automaton model combined bottleneck bus stop on-ramp
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Combined refraction and diffraction models for sea waves over complicated topography and with currents in shallow water
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作者 Yin Baoshu and Jiang Decai Institute of Oceanology, Academia Sinica, Qingdao, China Ocean University of Qingdao, Qingdao, China 《Acta Oceanologica Sinica》 SCIE CAS CSCD 1990年第1期13-23,共11页
-Combined refraction and diffraction models in the form of linear parabolic approximation are derived through smallparameter method. More strictly theoretical basis and more accuracy in the models than Lozano's (1... -Combined refraction and diffraction models in the form of linear parabolic approximation are derived through smallparameter method. More strictly theoretical basis and more accuracy in the models than Lozano's (1980) are obtained. Some theoretical defects in Liu's model (1985) with consideration of current are not only found but also eliminated. More strict and accurate models are, therefore, presented in this paper.The calculation results and analysis in applying the models to actual wave field with consideration of bottom friction will be given in the following paper. 展开更多
关键词 OVER combined refraction and diffraction models for sea waves over complicated topography and with currents in shallow water
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山东省中医类医院卫生人力资源需求预测 被引量:5
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作者 楚美金 徐文 马漫遥 《中国卫生资源》 CSCD 北大核心 2023年第4期404-409,416,共7页
目的了解山东省中医类医院卫生人力资源的现状,预测卫生人力资源未来的需求量并提出合理建议,以期为相关部门制定中医药人力资源规划提供依据和数据支持。方法运用差分自回归移动平均(auto-regressive moving average,ARIMA)模型、灰色... 目的了解山东省中医类医院卫生人力资源的现状,预测卫生人力资源未来的需求量并提出合理建议,以期为相关部门制定中医药人力资源规划提供依据和数据支持。方法运用差分自回归移动平均(auto-regressive moving average,ARIMA)模型、灰色系统预测模型(grey system forecasting model,GM)中的GM(1,1)模型以及两者的线性组合模型预测2021—2025年山东省中医类医院卫生人力资源需求量,比较不同模型预测的精准度。结果组合模型的系统误差小,预测效果最好;卫生技术人员、执业(助理)医师、中医类别执业(助理)医师、注册护士、药师(士)及中药师(士)2025年对应的人力资源预测值分别是107457人、43304人、22807人、51372人、5718人、3242人。结论山东省中医类别执业(助理)医师数量储备充足,但中药师(士)相对短缺,人才结构不合理,医护比有待优化。建议政府适当地增加中药师(士)的编制,促进执业(助理)医师与中药师(士)平衡发展;增加对中医类医院的财政拨款,加强人才引进力度,创新人才培养机制,优化山东省中医药人才结构;制定科学合理的排班制度,提高护士的社会地位,进一步优化医护比。 展开更多
关键词 差分自回归移动平均模型auto-regressive moving average model ARIMA model GM(1 1)模型GM(1 1)model 组合模型combined model 中医药人力资源Chinese medicine human resources
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A new hybrid method with data‑characteristic‑driven analysis for artificial intelligence and robotics index return forecasting
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作者 Yue‑Jun Zhang Han Zhang Rangan Gupta 《Financial Innovation》 2023年第1期2019-2041,共23页
Forecasting returns for the Artificial Intelligence and Robotics Index is of great significance for financial market stability,and the development of the artificial intelligence industry.To provide investors with a mo... Forecasting returns for the Artificial Intelligence and Robotics Index is of great significance for financial market stability,and the development of the artificial intelligence industry.To provide investors with a more reliable reference in terms of artificial intelligence index investment,this paper selects the NASDAQ CTA Artificial Intelligence and Robotics(AIRO)Index as the research target,and proposes innovative hybrid methods to forecast returns by considering its multiple structural characteristics.Specifically,this paper uses the ensemble empirical mode decomposition(EEMD)method and the modified iterative cumulative sum of squares(ICSS)algorithm to decompose the index returns and identify the structural breakpoints.Furthermore,it combines the least-square support vector machine approach with the particle swarm optimization method(PSO-LSSVM)and the generalized autoregressive conditional heteroskedasticity(GARCH)type models to construct innovative hybrid forecasting methods.On the one hand,the empirical results indicate that the AIRO index returns have complex structural characteristics,and present time-varying and nonlinear characteristics with high complexity and mutability;on the other hand,the newly proposed hybrid forecasting method(i.e.,the EEMD-PSO-LSSVM-ICSS-GARCH models)which considers these complex structural characteristics,can yield the optimal forecasting performance for the AIRO index returns. 展开更多
关键词 Artificial Intelligence and Robotics index return forecasting PSO-LSSVM model GARCH model Decomposition and integration model Combination model
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Accurate and rapid error estimation on global gravitational field from current GRACE and future GRACE Follow-On missions 被引量:34
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作者 郑伟 许厚泽 +1 位作者 钟敏 员美娟 《Chinese Physics B》 SCIE EI CAS CSCD 2009年第8期3597-3604,共8页
Firstly, the new combined error model of cumulative geoid height influenced by four error sources, including the inter-satellite range-rate of an interferometric laser (K-band) ranging system, the orbital position a... Firstly, the new combined error model of cumulative geoid height influenced by four error sources, including the inter-satellite range-rate of an interferometric laser (K-band) ranging system, the orbital position and velocity of a global positioning system (GPS) receiver and non-conservative force of an accelerometer, is established from the perspectives of the power spectrum principle in physics using the semi-analytical approach. Secondly, the accuracy of the global gravitational field is accurately and rapidly estimated based on the combined error model; the cumulative geoid height error is 1.985× 10^-1 m at degree 120 based on GRACE Level 1B measured observation errors of the year 2007 published by the US Jet Propulsion Laboratory (JPL), and the cumulative geoid height error is 5.825 × 10^-2 m at degree 360 using GRACE Follow-On orbital altitude 250 km and inter-satellite range 50 km. The matching relationship of accuracy indexes from GRACE Follow-On key payloads is brought forward, and the dependability of the combined error model is validated. Finally, the feasibility of high-accuracy and high-resolution global gravitational field estimation from GRACE Follow-On is demonstrated based on different satellite orbital altitudes. 展开更多
关键词 global gravitational field GRACE Follow-On semi-analytical approach combined error model
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Forecasting China’s natural gas consumption based on a combination model 被引量:10
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作者 Gang Xu Weiguo W ang 《Journal of Natural Gas Chemistry》 EI CAS CSCD 2010年第5期493-496,共4页
Ensuring a sufficient energy supply is essential to a country. Natural gas constitutes a vital part in energy supply and therefore forecasting natural gas consumption reliably and accurately is an essential part of a ... Ensuring a sufficient energy supply is essential to a country. Natural gas constitutes a vital part in energy supply and therefore forecasting natural gas consumption reliably and accurately is an essential part of a country's energy policy. Over the years, studies have shown that a combinative model gives better projected results compared to a single model. In this study, we used Polynomial Curve and Moving Average Combination Projection (PCMACP) model to estimate the future natural gas consumption in China from 2009 to 2015. The new proposed PCMACP model shows more reliable and accurate results: its Mean Absolute Percentage Error (MAPE) is less than those of any previous models within the investigated range. According to the PCMACP model, the average annual growth rate will increase for the next 7 years and the amount of natural gas consumption will reach 171600 million cubic meters in 2015 in China. 展开更多
关键词 natural gas consumption forecasting combination model
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Micro Mechanical Model of 3D Woven Composites 被引量:9
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作者 周储伟 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2005年第1期40-46,共7页
A combined beam model representing the periodicity of the microstructure and micro deformation of 3D woven composites is developed for predicting mechanical properties. The model considers the effects of off axial ten... A combined beam model representing the periodicity of the microstructure and micro deformation of 3D woven composites is developed for predicting mechanical properties. The model considers the effects of off axial tension/compression and bending/shearing couplings as well as the mutual reactions of fiber yarns. The method determining microstructure by using woven parameters is described for a typical 3D woven composite material. An analytical cell, constructed by a minimum periodic section of yarn and interlayer matrix, is adopted. Micro stresses in the cell under in-plane tensile loading are obtained by using the proposed beam model and macro modulus is then obtained by the averaging method. Material tests and a 2D micro FEM analysis are made to evaluate this model. Analyses reveal that micro stress caused by tensile/bending coupling effect is not negligible in the stress analysis. 展开更多
关键词 3D woven composites micro mechanics bending/shear coupling off axial effect combined beam model
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医院季度收入预测的比较研究
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作者 庞振陆 袁依 +2 位作者 崔庆霞 马桂峰 李望晨 《中国卫生资源》 北大核心 2022年第5期577-580,587,共5页
目的 探讨具有季度波动和长期趋势特征事物预测问题的方法论,为卫生领域同类预测问题提供定量决策方法论依据。方法 以某所医院季度收入预测作为实证算例载体,分别用乘积季节SARIMA法、X11-ARIMA法、X11-曲线函数外推法建立简单组合模... 目的 探讨具有季度波动和长期趋势特征事物预测问题的方法论,为卫生领域同类预测问题提供定量决策方法论依据。方法 以某所医院季度收入预测作为实证算例载体,分别用乘积季节SARIMA法、X11-ARIMA法、X11-曲线函数外推法建立简单组合模型以及二次加权组合模型。结果 乘积季节SARIMA模型、X11-ARIMA模型、X11-二次多项式的平均相对误差分别为1.28%、0.96%、1.11%。对以上简单组合模型继续进行深度加权组合,预测误差为0.70%,模型预测性能更优。结论 SARIMA模型、X11-ARIMA模型、X11-二次多项式以及二次组合模型对于局部周期性波动、全局稳定性趋势的时序数据资料拟合效果不错;对于卫生管理领域预测问题有适用性,鉴于多种匹配方法原理不同、信息利用差异大,基于多种方法的二次组合模型取得更优性能。 展开更多
关键词 医院收入revenue of hospital 简单模型simple model 二次加权组合模型quadratic weighted combination model 预测prediction 比较comparative
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A Novel Approach for QoS Prediction Based on Bayesian Combinational Model 被引量:3
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作者 Pengcheng Zhang Yingtao Sun +2 位作者 Hareton Leung Meijun Xu Wenrui Li 《China Communications》 SCIE CSCD 2016年第11期269-280,共12页
As an important factor in evaluating service,QoS(Quality of Service) has drawn more and more concerns with the rapid increasing of Web services. However,due to the great volatility of services in Mobile Internet envir... As an important factor in evaluating service,QoS(Quality of Service) has drawn more and more concerns with the rapid increasing of Web services. However,due to the great volatility of services in Mobile Internet environments,such as internet of vehicles,Web services often do not work as announced and thus cause unacceptable problems. QoS prediction can avoid failure before it takes place,which is considered a more effective way to assure quality. However,Current QoS prediction approaches neither consider the highly dynamic of Web services,nor maintain good prediction performance all the time. Consequently we propose a novel Bayesian combinational model to predict QoS by continuously adjusting credit values of the basic models so as to keep good prediction accuracy. QoS attributes such as response time,throughput and reliability are used to validate the proposed model. Experimental results show that the model can provide stable prediction results in Mobile Internet environments. 展开更多
关键词 internet of vehicles web service quality of service bayesian combinational model
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Predicting Surface Urban Heat Island in Meihekou City, China: A Combination Method of Monte Carlo and Random Forest 被引量:3
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作者 ZHANG Yao LIU Jiafu WEN Zhuyun 《Chinese Geographical Science》 SCIE CSCD 2021年第4期659-670,共12页
Given the rapid urbanization worldwide, Urban Heat Island(UHI) effect has been a severe issue limiting urban sustainability in both large and small cities. In order to study the spatial pattern of Surface urban heat i... Given the rapid urbanization worldwide, Urban Heat Island(UHI) effect has been a severe issue limiting urban sustainability in both large and small cities. In order to study the spatial pattern of Surface urban heat island(SUHI) in China’s Meihekou City, a combination method of Monte Carlo and Random Forest Regression(MC-RFR) is developed to construct the relationship between landscape pattern indices and Land Surface Temperature(LST). In this method, Monte Carlo acceptance-rejection sampling was added to the bootstrap layer of RFR to ensure the sensitivity of RFR to outliners of SUHI effect. The SHUI in 2030 was predicted by using this MC-RFR and the modeled future landscape pattern by Cellular Automata and Markov combination model(CA-Markov). Results reveal that forestland can greatly alleviate the impact of SUHI effect, while reasonable construction of urban land can also slow down the rising trend of SUHI. MC-RFR performs better for characterizing the relationship between landscape pattern and LST than single RFR or Linear Regression model. By 2030, the overall SUHI effect of Meihekou will be greatly enhanced, and the center of urban development will gradually shift to the central and western regions of the city. We suggest that urban designer and managers should concentrate vegetation and disperse built-up land to weaken the SUHI in the construction of new urban areas for its sustainability. 展开更多
关键词 Monte Carlo and Random Forest Regression(MC-RFR) landscape pattern surface heat island effect Cellular Automata and Markov combination model(CA-Markov)
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