Accurate short-term photovoltaic(PV)output forecasting is beneficial for increasing grid stabil-ity and enhancing the capacity for photovoltaic power absorption.In response to the challenges faced by commonly used pho...Accurate short-term photovoltaic(PV)output forecasting is beneficial for increasing grid stabil-ity and enhancing the capacity for photovoltaic power absorption.In response to the challenges faced by commonly used photovoltaic forecasting methods,which struggle to handle issues such as non-u-niform lengths of time series data for power generation and meteorological conditions,overlapping photovoltaic characteristics,and nonlinear correlations,an improved method that utilizes spectral clustering and dynamic time warping(DTW)for selecting similar days is proposed to optimize the dataset along the temporal dimension.Furthermore,XGBoost is employed for recursive feature selec-tion.On this basis,to address the issue that single forecasting models excel at capturing different data characteristics and tend to exhibit significant prediction errors under adverse meteorological con-ditions,an improved forecasting model based on Stacking and weighted fusion is proposed to reduce the independent bias and variance of individual models and enhance the predictive accuracy.Final-ly,experimental validation is carried out using real data from a photovoltaic power station in the Xi-aoshan District of Hangzhou,China,demonstrating that the proposed method can still achieve accu-rate and robust forecasting results even under conditions of significant meteorological fluctuations.展开更多
The structure and working principle of a self-deigned high pressure electronic pneumatic pressure reducing valve (EPPRV) with slide pilot are introduced.The resistance value formulas and the relationship between the r...The structure and working principle of a self-deigned high pressure electronic pneumatic pressure reducing valve (EPPRV) with slide pilot are introduced.The resistance value formulas and the relationship between the resistance and pressure of three typical pneumatic resistances are obtained.Then,the method of static characteristics analysis only considering pneumatic resistances is proposed,the resistance network from gas supply to load is built up,and the mathematical model is derived from the flow rate formulas and flow conservation equations,with the compressibility of high pressure gas and temperature drop during the expansion considered in the model.Finally,the pilot spool displacement of 1.5 mm at an output pressure of 15MPa and the enlarging operating stroke of the pilot spool are taken as optimization targets,and the optimization is carried out based on genetic algorithm and the model mentioned above.The results show that the static characteristics of the EPPRV are significantly improved.The idea of static characteristics analysis and optimization based on pneumatic resistance network is valuable for the design of pneumatic components or system.展开更多
This paper systematiedy expounds the history and present situation of tbe research &application of strip-parttal mining at home and abroad. Tbe prospect of using strip-parttal miningmcthod to mine under balldings ...This paper systematiedy expounds the history and present situation of tbe research &application of strip-parttal mining at home and abroad. Tbe prospect of using strip-parttal miningmcthod to mine under balldings (structures) at the present situation of market economy is also expounded here Strata & surface subsidence mechanism of atrip-partni mining the optimization ofthe width of unit goaf & coal pillar as well as the calculation method of surface subsidence pridictionbased on Holding-Ptate Control Theory and Coal Pillar Long-term Stability, which are our researchachivements in recent years about strata & surface subsidence control in strip-partial mining, arethe main points introdued bere.展开更多
The choice of time delay and embedding dimension is very important to the phase space reconstruction of any chaotic time series. In this paper, we determine optimal time delay by computing autocorrelation function of ...The choice of time delay and embedding dimension is very important to the phase space reconstruction of any chaotic time series. In this paper, we determine optimal time delay by computing autocorrelation function of time series. Optimal embedding dimension is given by means of the relation between embedding dimension and correlation dimension of chaotic time series. Based on the methods above, we choose ANN model to appoximate the given true system. At the same time, a new algorithm is applied to determine the network weights. At the end of this paper, the theory above is demonstrated through the research of time series generated by Logistic map.展开更多
Because of favorable mechanical properties,deformation resistance and being conducive to environmental protection,honeycomb fabricated plastic pavement slabs are highly recommended these years.At present,most studies ...Because of favorable mechanical properties,deformation resistance and being conducive to environmental protection,honeycomb fabricated plastic pavement slabs are highly recommended these years.At present,most studies focus on the performance of plastic materials,however,the dimension optimization of fabricated plastic pavement slab is rarely mentioned.In this paper,an optimized geometry of the honeycomb pavement slab was determined through finite element analysis.Mechanical response of honeycomb slabs with different internal dimensions and external dimensions were explored.Several dimension factors were taken into consideration including the side length,rib thickness,the thickness of both top and bottom slabs of honeycomb structure and the length,the width and the thickness of the fabricated plastic slab.The results showed that honeycomb pavement slab with 6 cm bottom slab,12 cm top slab,18 cm side length and 6 cm rib thickness is recommended,additionally,an external dimension of 4 m×4 m×0.45 m is suggested.Then,the mechanical responses of this optimized fabricated plastic slab were further investigated.Significance of different influencing factors,including wheel load,elastic modulus of plastic material,base layer thickness,soil foundation modulus and base layer modulus were ranked.展开更多
基金Supported by the National Natural Science Foundation of China(No.52005442)the Technology Project of Zhejiang Huayun Information Technology Co.,Ltd.(No.HYJT/JS-2020-004).
文摘Accurate short-term photovoltaic(PV)output forecasting is beneficial for increasing grid stabil-ity and enhancing the capacity for photovoltaic power absorption.In response to the challenges faced by commonly used photovoltaic forecasting methods,which struggle to handle issues such as non-u-niform lengths of time series data for power generation and meteorological conditions,overlapping photovoltaic characteristics,and nonlinear correlations,an improved method that utilizes spectral clustering and dynamic time warping(DTW)for selecting similar days is proposed to optimize the dataset along the temporal dimension.Furthermore,XGBoost is employed for recursive feature selec-tion.On this basis,to address the issue that single forecasting models excel at capturing different data characteristics and tend to exhibit significant prediction errors under adverse meteorological con-ditions,an improved forecasting model based on Stacking and weighted fusion is proposed to reduce the independent bias and variance of individual models and enhance the predictive accuracy.Final-ly,experimental validation is carried out using real data from a photovoltaic power station in the Xi-aoshan District of Hangzhou,China,demonstrating that the proposed method can still achieve accu-rate and robust forecasting results even under conditions of significant meteorological fluctuations.
基金Project(50575202) supported by the National Natural Science Foundation of China
文摘The structure and working principle of a self-deigned high pressure electronic pneumatic pressure reducing valve (EPPRV) with slide pilot are introduced.The resistance value formulas and the relationship between the resistance and pressure of three typical pneumatic resistances are obtained.Then,the method of static characteristics analysis only considering pneumatic resistances is proposed,the resistance network from gas supply to load is built up,and the mathematical model is derived from the flow rate formulas and flow conservation equations,with the compressibility of high pressure gas and temperature drop during the expansion considered in the model.Finally,the pilot spool displacement of 1.5 mm at an output pressure of 15MPa and the enlarging operating stroke of the pilot spool are taken as optimization targets,and the optimization is carried out based on genetic algorithm and the model mentioned above.The results show that the static characteristics of the EPPRV are significantly improved.The idea of static characteristics analysis and optimization based on pneumatic resistance network is valuable for the design of pneumatic components or system.
文摘This paper systematiedy expounds the history and present situation of tbe research &application of strip-parttal mining at home and abroad. Tbe prospect of using strip-parttal miningmcthod to mine under balldings (structures) at the present situation of market economy is also expounded here Strata & surface subsidence mechanism of atrip-partni mining the optimization ofthe width of unit goaf & coal pillar as well as the calculation method of surface subsidence pridictionbased on Holding-Ptate Control Theory and Coal Pillar Long-term Stability, which are our researchachivements in recent years about strata & surface subsidence control in strip-partial mining, arethe main points introdued bere.
基金The projectis supported by National Natural Science Foundation of China(N o.79970 0 4 3)
文摘The choice of time delay and embedding dimension is very important to the phase space reconstruction of any chaotic time series. In this paper, we determine optimal time delay by computing autocorrelation function of time series. Optimal embedding dimension is given by means of the relation between embedding dimension and correlation dimension of chaotic time series. Based on the methods above, we choose ANN model to appoximate the given true system. At the same time, a new algorithm is applied to determine the network weights. At the end of this paper, the theory above is demonstrated through the research of time series generated by Logistic map.
基金This work was supported by the National Key R&D Program of China(No.2018YFE0103800)the National Natural Science Foundation of China(Grant No.51978068)+1 种基金the Natural Science Foundation of Shaanxi Province(No.2021JQ-268)the Fundamental Research Funds for the Central Universities,CHD(No.300102211305).The authors gratefully acknowledge their financial support.
文摘Because of favorable mechanical properties,deformation resistance and being conducive to environmental protection,honeycomb fabricated plastic pavement slabs are highly recommended these years.At present,most studies focus on the performance of plastic materials,however,the dimension optimization of fabricated plastic pavement slab is rarely mentioned.In this paper,an optimized geometry of the honeycomb pavement slab was determined through finite element analysis.Mechanical response of honeycomb slabs with different internal dimensions and external dimensions were explored.Several dimension factors were taken into consideration including the side length,rib thickness,the thickness of both top and bottom slabs of honeycomb structure and the length,the width and the thickness of the fabricated plastic slab.The results showed that honeycomb pavement slab with 6 cm bottom slab,12 cm top slab,18 cm side length and 6 cm rib thickness is recommended,additionally,an external dimension of 4 m×4 m×0.45 m is suggested.Then,the mechanical responses of this optimized fabricated plastic slab were further investigated.Significance of different influencing factors,including wheel load,elastic modulus of plastic material,base layer thickness,soil foundation modulus and base layer modulus were ranked.
